Andrea Harrington

Immunohistochemical localization of substance P NK1 receptor in guinea pig distal colon

Publisher: Wiley

Date: 21-06-2005

DOI: 10.1111/J.1365-2982.2005.00680.X

Abstract: Neurokinin receptors facilitate tachykinin mediated intestinal motility and secretion. Distribution of Substance P (SP) neurokinin 1 receptor (NK1r) immunoreactivity (IR) has been previously characterized in guinea pig ileum, but not colon. This study localizes NK1rs in guinea pig distal colon. Neurons were double labelled for NK1r and either acetylcholine transferase (ChAT), calbindin (calb), neuropeptide Y (NPY), nitric oxide synthase (NOS) or SP. The NK1r endocytosis was induced by 10(-5) mol L(-1) SP, septide, [SarMet] SP or neurokinin A. In guinea pig distal colon, NK1r-IR was present on 70% of submucosal neurons. Sixty-threepercent of the NK1r-IR submucosal neurons were ChAT-IR, 16% calb/SP-IR, 19% NPY-IR and 14% NOS-IR neurons. The NK1r-IR was present on 5% of myenteric neurons. Of these 63% were ChAT-IR, 16% calb-IR neurons and 25% NOS-IR. The NK1rs were also on myenteric plexus interstitial cells of Cajal and on circular muscle. In guinea pig distal colon, NK1rs were on 70% of submucosal neurons including all three secretomotor neuron subtypes and sensory neurons, suggesting NK1rs have a major role in neuronal control of mucosal reflexes. The NK1rs were on few myenteric neurons but were dense on muscle cells, suggesting NK1rs affect motility through neuro-muscular rather than neuro-neuronal transmission.

Peripheral and central neuroplasticity in a mouse model of endometriosis

Publisher: Wiley

Date: 22-05-2023

DOI: 10.1111/JNC.15843

Abstract: Chronic pelvic pain (CPP) is the most debilitating symptom of gynaecological disorders such as endometriosis. However, it remains unclear how sensory neurons from pelvic organs affected by endometriosis, such as the female reproductive tract, detect and transmit nociceptive events and how these signals are processed within the central nervous system (CNS). Using a previously characterized mouse model of endometriosis, we investigated whether the increased pain sensitivity occurring in endometriosis could be attributed to (i) changes in mechanosensory properties of sensory afferents innervating the reproductive tract, (ii) alterations in sensory input from reproductive organs to the spinal cord or (iii) neuroinflammation and sensitization of spinal neural circuits. Mechanosensitivity of vagina‐innervating primary afferents was examined using an ex vivo single‐unit extracellular recording preparation. Nociceptive signalling from the vagina to the spinal cord was quantified by phosphorylated MAP kinase ERK1/2 immunoreactivity. Immunohistochemistry was used to determine glial and neuronal circuit alterations within the spinal cord. We found that sensory afferents innervating the rostral, but not caudal portions of the mouse vagina, developed mechanical hypersensitivity in endometriosis. Nociceptive signalling from the vagina to the spinal cord was significantly enhanced in mice with endometriosis. Moreover, mice with endometriosis developed microgliosis, astrogliosis and enhanced substance P neurokinin‐1 receptor immunoreactivity within the spinal cord, suggesting the development of neuroinflammation and sensitization of spinal circuitry in endometriosis. These results demonstrate endometriosis‐induced neuroplasticity occurring at both peripheral and central sites of sensory afferent pathways. These findings may help to explain the altered sensitivity to pain in endometriosis and provide a novel platform for targeted pain relief treatments for this debilitating disorder. image

Translating peripheral bladder afferent mechanosensitivity to neuronal activation within the lumbosacral spinal cord of mice.

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-12-2018

DOI: 10.1097/J.PAIN.0000000000001453

Abstract: Primary afferent neurons transduce distension of the bladder wall into action potentials that are relayed into the spinal cord and brain, where autonomic reflexes necessary for maintaining continence are coordinated with pathways involved in sensation. However, the relationship between spinal circuits involved with physiological and nociceptive signalling from the bladder has only been partially characterised. We used ex vivo bladder afferent recordings to characterise mechanosensitive afferent responses to graded distension (0-60 mm Hg) and retrograde tracing from the bladder wall to identify central axon projections within the dorsal horn of the lumbosacral (LS) spinal cord. Labelling of dorsal horn neurons with phosphorylated-MAP-kinase (pERK), combined with labelling for neurochemical markers (calbindin, calretinin, gamma aminobutyric acid, and parvalbumin) after in vivo bladder distension (20-60 mm Hg), was used to identify spinal cord circuits processing bladder afferent input. Ex vivo bladder distension evoked an increase in primary afferent output, and the recruitment of both low- and high-threshold mechanosensitive afferents. Retrograde tracing revealed bladder afferent projections that localised with pERK-immunoreactive dorsal horn neurons within the superficial laminae (superficial dorsal horn), dorsal gray commissure, and lateral collateral tracts of the LS spinal cord. Populations of pERK-immunoreactive neurons colabelled with calbindin, calretinin, or gamma aminobutyric acid, but not parvalbumin. Noxious bladder distension increased the percentage of pERK-immunoreactive neurons colabelled with calretinin. We identified LS spinal circuits supporting autonomic and nociceptive reflexes responsible for maintaining continence and bladder sensations. Our findings show for the first time that low- and high-threshold bladder afferents relay into similar dorsal horn circuits, with nociceptive signalling recruiting a larger number of neurons.

Innervation of the Gastrointestinal Tract by Spinal and Vagal Afferent Nerves

Publisher: Elsevier

Date: 2012

DOI: 10.1016/B978-0-12-382026-6.00024-5

Selenoether oxytocin analogues have analgesic properties in a mouse model of chronic abdominal pain

Publisher: Springer Science and Business Media LLC

Date: 30-01-2014

DOI: 10.1038/NCOMMS4165

Abstract: Poor oral availability and susceptibility to reduction and protease degradation is a major hurdle in peptide drug development. However, drugable receptors in the gut present an attractive niche for peptide therapeutics. Here we demonstrate, in a mouse model of chronic abdominal pain, that oxytocin receptors are significantly upregulated in nociceptors innervating the colon. Correspondingly, we develop chemical strategies to engineer non-reducible and therefore more stable oxytocin analogues. Chemoselective selenide macrocyclization yields stabilized analogues equipotent to native oxytocin. Ultra-high-field nuclear magnetic resonance structural analysis of native oxytocin and the seleno-oxytocin derivatives reveals that oxytocin has a pre-organized structure in solution, in marked contrast to earlier X-ray crystallography studies. Finally, we show that these seleno-oxytocin analogues potently inhibit colonic nociceptors both in vitro and in vivo in mice with chronic visceral hypersensitivity. Our findings have potentially important implications for clinical use of oxytocin analogues and disulphide-rich peptides in general.

¹⁸ F-Sodium Fluoride Positron Emission Tomography Activity Predicts the Development of New Coronary Artery Calcifications

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-12-2020

DOI: 10.1161/ATVBAHA.120.315364

Abstract: The coronary calcium score (CCS) predicts cardiovascular disease risk in in iduals with diabetes mellitus, and rate of progression of CCS is an additional and incremental marker of risk. 18 F-sodium fluoride positron emission tomography ( 18 F-NaF PET) detects early and active calcifications within the vasculature. We aimed to ascertain the relationship between 18 F-NaF PET activity and CCS progression in patients with diabetes mellitus. We identified in iduals between 50 and 80 years with diabetes mellitus and no history of clinical coronary artery disease. Those with a CCS ≥10 were invited to undergo 18 F-NaF PET scanning and then repeat CCS years later. 18 F-NaF PET and CCS analysis were performed on a per-coronary and a per-patient level. We compared the proportion of CCS progressors in 18 F-NaF PET–positive versus 18 F-NaF PET–negative coronary arteries. Forty-one participants with 163 coronary arteries underwent follow-up CCS 2.8±0.5 years later. 18 F-NaF PET–positive coronary arteries (n=52) were more likely to be CCS progressors, compared with negative coronary arteries (n=111 86.5% versus 52.3%, P .001). Adjusting for baseline CCS, 18 F-NaF PET–positive disease was an independent predictor of subsequent CCS progression (odds ratio, 2.92 [95% CI, 1.32–6.45], P =0.008). All subjects (100%, 15/15) with ≥2 18 F-NaF–positive coronary arteries progressed in CCS. In subjects with diabetes mellitus, 18 F-NaF PET positivity at baseline, independently predicted the progression of calcifications within the coronary arteries 2.8 years later. These findings suggest 18 F-NaF PET may be a promising technique for earlier identification of patients at higher risk of cardiovascular events.

Cholinergic neurotransmission and muscarinic receptors in the enteric nervous system

Publisher: Elsevier BV

Date: 02-2010

DOI: 10.1016/J.PROGHI.2009.10.001

Abstract: There is a rich knowledge of the enteric nervous system (ENS), especially the neurochemical and neurophysiological properties of enteric neurons and how they communicate in neural circuits underlying intestinal reflexes. The major pathways of excitatory transmission within the ENS are mediated by cholinergic and tachykinergic transmission, with transmitters Acetylcholine (ACh) and Tachykinins (TK), respectively, producing excitatory potentials in post-synaptic effectors. This review focuses on the cholinergic pathways of the ENS. The cholinergic circuitry of the ENS is extensive and mediates motility (muscular) and secretory (mucosal) reflexes, in addition to intrinsic sensory and vascular reflexes. The capacity of ACh to mediate multiple physiologically significant intestinal reflexes is largely due to having multiple sites of neuronal and non-neuronal release and reception within the intestine. This review will concentrate on one of two classes of ACh receptors, Muscarinic receptors (mAChr), in particular their location and function in mediating synaptic transmission within enteric circuits underlying intestinal reflexes.

Association between vitamin K1 intake and mortality in the Danish Diet, Cancer, and Health cohort

Publisher: Springer Science and Business Media LLC

Date: 30-09-2021

DOI: 10.1007/S10654-021-00806-9

Abstract: Reported associations between vitamin K 1 and both all-cause and cause-specific mortality are conflicting. The 56,048 participants from the Danish Diet, Cancer, and Health prospective cohort study, with a median [IQR] age of 56 [52–60] years at entry and of whom 47.6% male, were followed for 23 years, with 14,083 reported deaths. Of these, 5015 deaths were CVD-related, and 6342 deaths were cancer-related. Intake of vitamin K 1 (phylloquinone) was estimated from a food-frequency questionnaire (FFQ), and its relationship with mortality outcomes was investigated using Cox proportional hazards models. A moderate to high (87–192 µg/d) intake of vitamin K 1 was associated with a lower risk of all-cause [HR (95%CI) for quintile 5 vs quintile 1: 0.76 (0.72, 0.79)], cardiovascular disease (CVD)-related [quintile 5 vs quintile 1: 0.72 (0.66, 0.79)], and cancer-related mortality [quintile 5 vs quintile 1: 0.80 (0.75, 0.86)], after adjusting for demographic and lifestyle confounders. The association between vitamin K 1 intake and cardiovascular disease-related mortality was present in all subpopulations (categorised according to sex, smoking status, diabetes status, and hypertension status), while the association with cancer-related mortality was only present in current/former smokers (p for interaction = 0.002). These findings suggest that promoting adequate intakes of foods rich in vitamin K 1 may help to reduce all-cause, CVD-related, and cancer-related mortality at the population level.

Linaclotide treatment reduces endometriosis-associated vaginal hyperalgesia and mechanical allodynia through viscerovisceral cross-talk

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 16-07-2019

DOI: 10.1097/J.PAIN.0000000000001657

Abstract: Endometriosis, an estrogen-dependent chronic inflammatory disease, is the most common cause of chronic pelvic pain. Here, we investigated the effects of linaclotide, a Food and Drug Administration–approved treatment for IBS-C, in a rat model of endometriosis. Eight weeks after endometrium transplantation into the intestinal mesentery, rats developed endometrial lesions as well as vaginal hyperalgesia to distension and decreased mechanical hind paw withdrawal thresholds. Daily oral administration of linaclotide, a peripherally restricted guanylate cyclase-C (GC-C) agonist peptide acting locally within the gastrointestinal tract, increased pain thresholds to vaginal distension and mechanical hind paw withdrawal thresholds relative to vehicle treatment. Furthermore, using a cross-over design, administering linaclotide to rats previously administered vehicle resulted in increased hind paw withdrawal thresholds, whereas replacing linaclotide with vehicle treatment decreased hind paw withdrawal thresholds. Retrograde tracing of sensory afferent nerves from the ileum, colon, and vagina revealed that central terminals of these afferents lie in close apposition to one another within the dorsal horn of the spinal cord. We also identified dichotomizing dual-labelled ileal/colon innervating afferents as well as colon/vaginal dual-labelled neurons and a rare population of triple traced ileal/colon/vaginal neurons within thoracolumbar DRG. These observations provide potential sources of cross-organ interaction at the level of the DRG and spinal cord. GC-C expression is absent in the vagina and endometrial cysts suggesting that the actions of linaclotide are shared through nerve pathways between these organs. In summary, linaclotide may offer a novel therapeutic option not only for treatment of chronic endometriosis-associated pain, but also for concurrent treatment of comorbid chronic pelvic pain syndromes.

Comparative localization of colorectal sensory afferent central projections in the mouse spinal cord dorsal horn and caudal medulla dorsal vagal complex

Publisher: Wiley

Date: 14-10-2023

DOI: 10.1002/CNE.25546

Chronic intra-colonic linaclotide administration alters glial activation in a mouse model of chronic visceral hypersensitivity

Publisher: Elsevier BV

Date: 05-2020

DOI: 10.1016/S0016-5085(20)32687-1

Use of cardiovascular imaging in risk restratification of the diabetic patient

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 25-12-2020

DOI: 10.1097/MED.0000000000000611

Colonic afferent input and dorsal horn neuron activation differs between the thoracolumbar and lumbosacral spinal cord

Publisher: American Physiological Society

Date: 09-2019

DOI: 10.1152/AJPGI.00013.2019

Abstract: The distal colon is innervated by the splanchnic and pelvic nerves, which relay into the thoracolumbar and lumbosacral spinal cord, respectively. Although the peripheral properties of the colonic afferent nerves within these pathways are well studied, their input into the spinal cord remain ill defined. The use of dual retrograde tracing from the colon wall and lumen, in conjunction with in vivo colorectal distension and spinal neuronal activation labeling with phosphorylated MAPK ERK 1/2 (pERK), allowed us to identify thoracolumbar and lumbosacral spinal cord circuits processing colonic afferent input. In the thoracolumbar dorsal horn, central projections of colonic afferents were primarily labeled from the wall of the colon and localized in laminae I and V. In contrast, lumbosacral projections were identified from both lumen and wall tracing, present within various dorsal horn laminae, collateral tracts, and the dorsal gray commissure. Nonnoxious in vivo colorectal distension evoked significant neuronal activation (pERK-immunoreactivity) within the lumbosacral dorsal horn but not in thoracolumbar regions. However, noxious in vivo colorectal distension evoked significant neuronal activation in both the thoracolumbar and lumbosacral dorsal horn, with the distribution of activated neurons correlating to the pattern of traced projections. Dorsal horn neurons activated by colorectal distension were identified as possible populations of projection neurons or excitatory and inhibitory interneurons based on their neurochemistry. Our findings demonstrate how colonic afferents in splanchnic and pelvic pathways differentially relay mechanosensory information into the spinal cord and contribute to the recruitment of spinal cord pathways processing non-noxious and noxious stimuli. NEW & NOTEWORTHY In mice, retrograde tracing from the colon wall and lumen was used to identify unique populations of afferent neurons and central projections within the spinal cord dorsal horn. We show that there are pronounced differences between the spinal cord regions in the distribution pattern of colonic afferent central projections and the pattern of dorsal horn neuron activation evoked by colorectal distension. These findings demonstrate how colonic afferent input influences spinal processing of colonic mechanosensation.

Is breast arterial calcification associated with coronary artery disease? A systematic review and meta-analysis

Publisher: Public Library of Science (PLoS)

Date: 28-07-2020

DOI: 10.1371/JOURNAL.PONE.0236598

Olorinab (APD371), a peripherally acting, highly selective, full agonist of the cannabinoid receptor 2, reduces colitis-induced acute and chronic visceral hypersensitivity in rodents

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 13-04-2022

DOI: 10.1097/J.PAIN.0000000000002314

Abstract: Abdominal pain is a key symptom of inflammatory bowel disease and irritable bowel syndrome, for which there are inadequate therapeutic options. We tested whether olorinab—a highly selective, full agonist of the cannabinoid receptor 2 (CB 2 )—reduced visceral hypersensitivity in models of colitis and chronic visceral hypersensitivity (CVH). In rodents, colitis was induced by intrarectal administration of nitrobenzene sulfonic acid derivatives. Control or colitis animals were administered vehicle or olorinab (3 or 30 mg/kg) twice daily by oral gavage for 5 days, starting 1 day before colitis induction. Chronic visceral hypersensitivity mice were administered olorinab (1, 3, 10, or 30 mg/kg) twice daily by oral gavage for 5 days, starting 24 days after colitis induction. Visceral mechanosensitivity was assessed in vivo by quantifying visceromotor responses (VMRs) to colorectal distension. Ex vivo afferent recordings determined colonic nociceptor firing evoked by mechanical stimuli. Colitis and CVH animals displayed significantly elevated VMRs to colorectal distension and colonic nociceptor hypersensitivity. Olorinab treatment significantly reduced VMRs to control levels in colitis and CVH animals. In addition, olorinab reduced nociceptor hypersensitivity in colitis and CVH states in a concentration- and CB 2 -dependent manner. By contrast, olorinab did not alter VMRs nor nociceptor responsiveness in control animals. Cannabinoid receptor 2 mRNA was detected in colonic tissue, particularly within epithelial cells, and dorsal root ganglia, with no significant differences between healthy, colitis, and CVH states. These results demonstrate that olorinab reduces visceral hypersensitivity through CB 2 agonism in animal models, suggesting that olorinab may provide a novel therapy for inflammatory bowel disease– and irritable bowel syndrome–associated abdominal pain.

The hot mustard receptor's role in gut motor function

Publisher: Elsevier BV

Date: 08-2011

DOI: 10.1053/J.GASTRO.2011.06.028

Linaclotide inhibits colonic nociceptors and relieves abdominal pain via guanylate cyclase-C and extracellular cyclic guanosine 3′,5′- monophosphate

Publisher: Elsevier BV

Date: 12-2013

DOI: 10.1053/J.GASTRO.2013.08.017

Abstract: Linaclotide is a minimally absorbed agonist of guanylate cyclase-C (GUCY2C or GC-C) that reduces symptoms associated with irritable bowel syndrome with constipation (IBS-C). Little is known about the mechanism by which linaclotide reduces abdominal pain in patients with IBS-C. We determined the effects of linaclotide on colonic sensory afferents in healthy mice and those with chronic visceral hypersensitivity. We assessed pain transmission by measuring activation of dorsal horn neurons in the spinal cord in response to noxious colorectal distention. Levels of Gucy2c messenger RNA were measured in tissues from mice using quantitative reverse transcription polymerase chain reaction and in situ hybridization. We used human intestinal cell lines to measure release of cyclic guanosine-3',5'-monophosphate (cGMP) by linaclotide. We performed a post-hoc analysis of data from a phase III, double-blind, parallel-group study in which 805 patients with IBS-C were randomly assigned to groups given an oral placebo or 290 μg linaclotide once daily for 26 weeks. We quantified changes in IBS-C symptoms, including abdominal pain. In mice, linaclotide inhibited colonic nociceptors with greater efficacy during chronic visceral hypersensitivity. Intra-colonic administration of linaclotide reduced signaling of noxious colorectal distention to the spinal cord. The colonic mucosa, but not neurons, was found to express linaclotide's target, GC-C. The downstream effector of GC-C, cGMP, was released after administration of linaclotide and also inhibited nociceptors. The effects of linaclotide were lost in Gucy2c(-/-) mice and prevented by inhibiting cGMP transporters or removing the mucosa. During 26 weeks of linaclotide administration, a significantly greater percentage of patients (70%) had at least a 30% reduction in abdominal pain compared with patients given placebo (50%). We have identified an analgesic mechanism of linaclotide: it activates GC-C expressed on mucosal epithelial cells, resulting in the production and release of cGMP. This extracellular cGMP acts on and inhibits nociceptors, thereby reducing nociception. We also found that linaclotide reduces chronic abdominal pain in patients with IBS-C.

A syngeneic inoculation mouse model of endometriosis that develops multiple comorbid visceral and cutaneous pain like behaviours

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 15-12-2022

DOI: 10.1097/J.PAIN.0000000000002552

Abstract: Endometriosis is a chronic and debilitating condition, commonly characterised by chronic pelvic pain (CPP) and infertility. Chronic pelvic pain can be experienced across multiple pelvic organs, with comorbidities commonly effecting the bowel, bladder, and vagina. Despite research efforts into endometriosis pathophysiology, little is known about how endometriosis induces CPP, and as such, therapeutic interventions are lacking. The aim of this study was to characterise a syngeneic mouse model of endometriosis that mimics naturally occurring retrograde menstruation, thought to precede endometriosis development in patients, and determine whether these mice exhibit signs of CPP and altered behaviour. We characterised the development of endometriosis over 10 weeks following uterine tissue inoculation, measured in vivo and ex vivo hypersensitivity to mechanical stimuli across multiple visceral organs, and assessed alterations in animal spontaneous behaviour. We confirmed that inoculated uterine horn tissue formed into endometriosis lesions throughout the peritoneal cavity, with significant growth by 8 to 10 weeks post inoculation. Additionally, we found that mice with fully developed endometriosis displayed hypersensitivity evoked by (1) vaginal distension, (2) colorectal distension, (3) bladder distension, and (4) cutaneous thermal stimulation, compared to their sham counterparts. Moreover, endometriosis mice displayed alterations in spontaneous behaviour indicative of (5) altered bladder function and (6) anxiety. This model creates a foundation for mechanistical studies into the diffuse CPP associated with endometriosis and the development of targeted therapeutic interventions to improve the quality of life of women with endometriosis.

Pharmacological modulation of voltage-gated sodium (NaV) channels alters nociception arising from the female reproductive tract

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 20-08-2021

DOI: 10.1097/J.PAIN.0000000000002036

Abstract: Dyspareunia, also known as vaginal hyperalgesia, is a prevalent and debilitating symptom of gynaecological disorders such as endometriosis and vulvodynia. Despite this, the sensory pathways transmitting nociceptive information from female reproductive organs remain poorly characterised. As such, the development of specific treatments for pain associated with dyspareunia is currently lacking. Here, we examined, for the first time, (1) the mechanosensory properties of pelvic afferent nerves innervating the mouse vagina (2) the expression profile of voltage-gated sodium (Na V ) channels within these afferents and (3) how pharmacological modulation of these channels alters vaginal nociceptive signalling ex vivo, in vitro, and in vivo. We developed a novel afferent recording preparation and characterised responses of pelvic afferents innervating the mouse vagina to different mechanical stimuli. Single-cell reverse transcription-polymerase chain reaction determined mRNA expression of Na V channels within vagina-innervating dorsal root ganglia neurons. Vagina-innervating dorsal root ganglia neuroexcitability was measured using whole-cell patch-cl electrophysiology. Nociception evoked by vaginal distension was assessed by dorsal horn neuron activation within the spinal cord and quantification of visceromotor responses. We found that pelvic afferents innervating the vagina are tuned to detect various mechanical stimuli, with Na V channels abundantly expressed within these neurons. Pharmacological modulation of Na V channels (with veratridine or tetrodotoxin) correspondingly alters the excitability and mechanosensitivity of vagina-innervating afferents, as well as dorsal horn neuron activation and visceromotor responses evoked by vaginal distension. This study identifies potential molecular targets that can be used to modulate vaginal nociceptive signalling and aid in the development of approaches to manage endometriosis and vulvodynia-related dyspareunia.

The T type calcium channel CaV3.2 regulates bladder afferent responses to mechanical stimuli.

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 21-10-2022

DOI: 10.1097/J.PAIN.0000000000002795

Abstract: The bladder wall is innervated by a complex network of afferent nerves that detect bladder stretch during filling. Sensory signals, generated in response to distension, are relayed to the spinal cord and brain to evoke physiological and painful sensations and regulate urine storage and voiding. Hyperexcitability of these sensory pathways is a key component in the development of chronic bladder hypersensitivity disorders including interstitial cystitis/bladder pain syndrome and overactive bladder syndrome. Despite this, the full array of ion channels that regulate bladder afferent responses to mechanical stimuli have yet to be determined. Here, we investigated the role of low-voltage-activated T-type calcium (Ca V 3) channels in regulating bladder afferent responses to distension. Using single-cell reverse-transcription polymerase chain reaction and immunofluorescence, we revealed ubiquitous expression of Ca V 3.2, but not Ca V 3.1 or Ca V 3.3, in in idual bladder-innervating dorsal root ganglia neurons. Pharmacological inhibition of Ca V 3.2 with TTA-A2 and ABT-639, selective blockers of T-type calcium channels, dose-dependently attenuated ex-vivo bladder afferent responses to distension in the absence of changes to muscle compliance. Further evaluation revealed that Ca V 3.2 blockers significantly inhibited both low- and high-threshold afferents, decreasing peak responses to distension, and delayed activation thresholds, thereby attenuating bladder afferent responses to both physiological and noxious distension. Nocifensive visceromotor responses to noxious bladder distension in vivo were also significantly reduced by inhibition of Ca V 3 with TTA-A2. Together, these data provide evidence of a major role for Ca V 3.2 in regulating bladder afferent responses to bladder distension and nociceptive signalling to the spinal cord.

Localization of muscarinic receptors M1R, M2R and M3R in the human colon

Publisher: Wiley

Date: 04-08-2010

DOI: 10.1111/J.1365-2982.2009.01456.X

Abstract: Muscarinic acetylcholine receptors (MR) are involved in multiple intestinal reflexes. The cellular localization of subtypes of MRs within enteric circuits mediating muscle and mucosal reflexes remains to be demonstrated. This study aimed to localize the three functionally significant subtypes of MRs in human colon. Reverse transcriptase-PCR was used to determine expression levels of muscarinic receptor subtype (MRs) M1Rs, M2Rs and M3Rs in human colon. Indirect immunofluorescence and confocal microscopy was used to localize MRs in cryostat-cut sections of human colon. Sections were double labeled for multiple cellular and neurochemical markers. Western blotting was used to confirm specificity of the muscarinic antisera used. All three MR subtypes were expressed in human colon. Immunoreactivity (IR) for M2Rs and M3Rs was most abundant in circular and longitudinal muscle. M1R-IR was most abundant on myenteric and submucosal nerve cells, both cholinergic and nitrergic. M3R-IR was also present on populations on myenteric nerve cell bodies. Immunoreactivity for all three receptors was present on nerve fibers in the circular muscle. In the human colon, subtypes of MRs were present on multiple cell types within the enteric circuits underlying motility, secretory and vasoactive reflexes. The cellular distribution for MRs found in this study agrees with data from functional studies, providing insight into the role MRs have in mediating enteric cholinergic neurotransmission.

Coronary 18F-sodium fluoride PET detects high-risk plaque features on optical coherence tomography and CT-angiography in patients with acute coronary syndrome

Publisher: Elsevier BV

Date: 02-2021

DOI: 10.1016/J.ATHEROSCLEROSIS.2020.12.010

Abstract: Sixty-two prospectively recruited patients with acute coronary syndrome (ACS) underwent multi-vessel OCT, In 62 patients (age, mean ± standard deviation (SD) = 61 ± 9 years, 85% male) the coronary segments with elevated

Activation of pruritogenic TGR5, MRGPRA3, and MRGPRC11 on colon-innervating afferents induces visceral hypersensitivity

Publisher: American Society for Clinical Investigation

Date: 17-10-2019

DOI: 10.1172/JCI.INSIGHT.131712

A Visceral Representation of Itch

Publisher: Elsevier BV

Date: 04-2201

DOI: 10.1016/S0016-5085(15)32505-1

Vitamin K1 intake and incident diabetes in the Danish Diet Cancer and Health Study

Publisher: The Endocrine Society

Date: 26-05-2023

DOI: 10.1210/CLINEM/DGAD293

Abstract: Observational studies have reported lower risks of type 2 diabetes with higher vitamin K1 intake, but these studies overlook effect modification due to known diabetes risk factors. To identify subgroups that might benefit from vitamin K1 intake, we examined associations between vitamin K1 intake and incident diabetes overall and in subpopulations at risk of diabetes. Participants from the prospective cohort, the Danish Diet, Cancer, and Health Study, with no history of diabetes were followed up for diabetes incidence. The association between intake of vitamin K1, estimated from a food frequency questionnaire completed at baseline, and incident diabetes was determined using multivariable-adjusted Cox proportional-hazards models. In 54 787 Danish residents with a median (interquartile range) age of 56 (52-60) years at baseline, 6700 in iduals were diagnosed with diabetes during 20.8 (17.3-21.6) years of follow-up. Vitamin K1 intake was inversely and linearly associated with incident diabetes (P & .0001). Compared to participants with the lowest vitamin K1 intake (median:57 µg/d), participants with the highest intakes (median:191 µg/d) had a 31% lower risk of diabetes (HR 95% CI, 0.69 0.64-0.74) after multivariable adjustments. The inverse association between vitamin K1 intake and incident diabetes was present in all subgroups (namely, men and women, ever and never smokers, low and high physical activity groups, and in participants who were normal to overweight and obese), with differences in absolute risk between subgroups. Higher intake of foods rich in vitamin K1 was associated with a lower risk of diabetes. If the associations observed are causal, our results indicate that more cases of diabetes would be prevented in subgroups at higher risk (men, smokers, participants with obesity, and those with low physical activity).

Identifying spinal sensory pathways activated by noxious esophageal acid

Publisher: Wiley

Date: 12-07-2013

DOI: 10.1111/NMO.12180

Abstract: The transient receptor potential vanilloid 1 (TRPV1) channel is critical for spinal afferent signaling of burning pain throughout the body. Such pain frequently originates from the esophagus, following acid reflux. The contribution of TRPV1 to spinal nociceptor signaling from the esophagus remains unclear. We aimed to identify the spinal afferent pathways that convey nociceptive signaling from the esophagus, specifically those sensitive to acid, and the extent to which TRPV1 contributes. Acid epsin (150 mM HCl/1 mg mL(-1) pepsin) or saline epsin was perfused into the esophageal lumen of anesthetized wild-type and TRPV1 null mice over 20 min, followed by atraumatic perfuse fixation and removal of the cervical and thoracic spinal cord and dorsal root ganglia (DRG). To identify neurons responsive to esophageal perfusate, immunolabeling for neuronal activation marker phosphorylated extracellular receptor-regulated kinase (pERK) was used. Labeling for calcitonin gene-related peptide (CGRP) and isolectin B4 (IB4) was then used to characterize responsive neurons. Esophageal acid epsin perfusion significantly increased the number of pERK-immunoreactive (IR) neurons in the DRG and the cervical and thoracic spinal cord dorsal horn (DH) relative to saline epsin (DRG P < 0.01 cervical DH P < 0.05 and thoracic DH P < 0.005). The number of pERK-IR neurons following acid perfusion was significantly attenuated in TRPV1 -/- mice (DH P < 0.05 and DRG P < 0.05). This study has identified populations of spinal afferent DRG neurons and DH neurons involved in signaling of noxious acid from the esophagus. There is a major contribution of TRPV1 to signaling within these pathways.

Sprouting of colonic afferent central terminals and increased spinal mitogen-activated protein kinase expression in a mouse model of chronic visceral hypersensitivity

Publisher: Wiley

Date: 12-04-2012

DOI: 10.1002/CNE.23042

Abstract: Visceral pain following infection or inflammation is a major clinical problem. Although we have knowledge of how peripheral endings of colonic afferents change in disease, their central projections have been overlooked. With neuroanatomical tracing and colorectal distension (CRD), we sought to identify colonic afferent central terminals (CACTs), the dorsal horn (DH) neurons activated by colonic stimuli in the thoracolumbar (T10-L1) DH, and determine how they are altered by postinflammatory chronic colonic mechanical hypersensitivity. Retrograde tracing from the colon identified CACTs in the DH, whereas immunohistochemistry for phosphorylated MAP kinase ERK 1/2 (pERK) identified DH neurons activated by CRD (80 mmHg). In healthy mice, CACTs were located primarily in DH laminae I (LI) and V (LV) and projected down middle and lateral DH collateral pathways. CRD evoked pERK immunoreactivity in DH neurons, the majority of which were located in LI and LV, the same regions as CACTs. In postinflammatory mice, CACTs were significantly increased in T12-L1 compared with healthy mice. Although CACTs remained abundant in LI, they were more widespread and were now present in deeper laminae. After CRD, significantly more DH neurons were pERK-IR postinflammation (T12-L1), with abundant expression in LI and deeper laminae. In both healthy and postinflammatory mice, many pERK neurons were in close apposition to CACTs, suggesting that colonic afferents can stimulate specific DH neurons in response to noxious CRD. Overall, we demonstrate that CACT density and the number of responsive DH neurons in the spinal cord increase postinflammation, which may facilitate aberrant central representation of colonic nociceptive signaling following chronic peripheral hypersensitivity.

A novel role for TRPM8 in visceral afferent function

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2011

DOI: 10.1016/J.PAIN.2011.01.027

Abstract: Transient receptor potential ion channel melastatin subtype 8 (TRPM8) is activated by cold temperatures and cooling agents, such as menthol and icilin. Compounds containing peppermint are reported to reduce symptoms of bowel hypersensitivity however, the underlying mechanisms of action are unclear. Here we determined the role of TRPM8 in colonic sensory pathways. Laser capture microdissection, quantitative reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence, and retrograde tracing were used to localise TRPM8 to colonic primary afferent neurons. In vitro extracellular single-fibre afferent recordings were used to determine the effect of TRPM8 channel activation on the chemosensory and mechanosensory function of colonic high-threshold afferent fibres. TRPM8 mRNA was present in colonic DRG neurons, whereas TRPM8 protein was present on nerve fibres throughout the wall of the colon. A subpopulation (24%, n=58) of splanchnic serosal and mesenteric afferents tested responded directly to icilin (5 μmol/L). Subsequently, icilin significantly desensitised afferents to mechanical stimulation (P<.0001 n=37). Of the splanchnic afferents responding to icilin, 21 (33%) also responded directly to the TRPV1 agonist capsaicin (3 μmol/L), and icilin reduced the direct chemosensory response to capsaicin. Icilin also prevented mechanosensory desensitization and sensitization induced by capsaicin and the TRPA1 agonist AITC (40 μmol/L), respectively. TRPM8 is present on a select population of colonic high threshold sensory neurons, which may also co-express TRPV1. TRPM8 couples to TRPV1 and TRPA1 to inhibit their downstream chemosensory and mechanosensory actions.

Vitamin K Intake and Atherosclerotic Cardiovascular Disease in the Danish Diet Cancer and Health Study

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 17-08-2021

DOI: 10.1161/JAHA.120.020551

Abstract: Dietary vitamin K (K 1 and K 2 ) may reduce atherosclerotic cardiovascular disease (ASCVD) risk via several mechanisms. However, studies linking vitamin K intake with incident ASCVD are limited. We aimed to determine the relationship between dietary vitamin K intake and ASCVD hospitalizations. In this prospective cohort study, participants from the Danish Diet, Cancer, and Health Study, with no prior ASCVD, completed a food‐frequency questionnaire at baseline and were followed up for hospital admissions of ASCVD ischemic heart disease, ischemic stroke, or peripheral artery disease. Intakes of vitamin K 1 and vitamin K 2 were estimated from the food‐frequency questionnaire, and their relationship with ASCVD hospitalizations was determined using Cox proportional hazards models. Among 53 372 Danish citizens with a median (interquartile range) age of 56 (52–60) years, 8726 in iduals were hospitalized for any ASCVD during 21 (17–22) years of follow‐up. Compared with participants with the lowest vitamin K 1 intakes, participants with the highest intakes had a 21% lower risk of an ASCVD‐related hospitalization (hazard ratio, 0.79 95% CI: 0.74–0.84), after multivariable adjustments for relevant demographic covariates. Likewise for vitamin K 2 , the risk of an ASCVD‐related hospitalization for participants with the highest intakes was 14% lower than participants with the lowest vitamin K 2 intake (hazard ratio, 0.86 95% CI, 0.81–0.91). Risk of ASCVD was inversely associated with diets high in vitamin K 1 or K 2 . The similar inverse associations with both vitamin K 1 and K 2 , despite very different dietary sources, highlight the potential importance of vitamin K for ASCVD prevention.

Ischaemic Stroke and the Echocardiographic Bubble Study

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.HLC.2018.07.007

Abstract: Patent foramen ovale (PFO) is a potential mechanism for paradoxical embolism in cryptogenic ischaemic stroke or transient ischaemic attack (TIA). PFO is typically demonstrated with agitated saline ("bubble study", BS) during echocardiography. We hypothesised that the BS is frequently requested in patients that have a readily identifiable cause of stroke, that any PFO detected is likely incidental, and its detection often does not alter management. This was a retrospective observational study of patients with recent ischaemic stroke/TIA referred for a BS. Patient demographics, stroke risk factors, vascular/cerebral imaging results and transoesophageal echocardiogram (TOE) reports were recorded. A "modified" Risk of Paradoxical Embolism (RoPE) score was calculated. Change in management was defined as antiplatelet/anticoagulant therapy alteration or referral for PFO closure. Bubble Study complications were recorded. Among 715 patients with ischaemic stroke/TIA referred for a BS, 8.7% had atrial fibrillation and 9.2% had carotid stenosis ≥70%. At least three stroke risk factors were present in 39.3% and only 47.1% of patients screened had a "modified" RoPE score of >5. A PFO was detected in 248 patients of whom only 31% (77/248) had a subsequent change in management. Of BS performed, 1/924 patients (0.1%) suffered a TIA as a complication. The echocardiographic BS is frequently performed in patients that have a readily identifiable cause of stroke and whose PFO unlikely relates to the stroke/TIA. Bubble Study findings resulted in a change in management in the minority. The procedure is safe but the complication rate warrants informed consent.

Disengaging spinal afferent nerve communication with the brain in live mice

Publisher: Springer Science and Business Media LLC

Date: 14-09-2022

DOI: 10.1038/S42003-022-03876-X

Abstract: Our understanding of how abdominal organs (like the gut) communicate with the brain, via sensory nerves, has been limited by a lack of techniques to selectively activate or inhibit populations of spinal primary afferent neurons within dorsal root ganglia (DRG), of live animals. We report a survival surgery technique in mice, where select DRG are surgically removed (unilaterally or bilaterally), without interfering with other sensory or motor nerves. Using this approach, pain responses evoked by rectal distension were abolished by bilateral lumbosacral L5-S1 DRG removal, but not thoracolumbar T13-L1 DRG removal. However, animals lacking T13-L1 or L5-S1 DRG both showed reduced pain sensitivity to distal colonic distension. Removal of DRG led to selective loss of peripheral CGRP-expressing spinal afferent axons innervating visceral organs, arising from discrete spinal segments. This method thus allows spinal segment-specific determination of sensory pathway functions in conscious, free-to-move animals, without genetic modification.

Multiple sodium channel isoforms mediate the pathological effects of Pacific ciguatoxin-1.

Publisher: Springer Science and Business Media LLC

Date: 22-02-2017

DOI: 10.1038/SREP42810

Abstract: Human intoxication with the seafood poison ciguatoxin, a dinoflagellate polyether that activates voltage-gated sodium channels (Na V ), causes ciguatera, a disease characterised by gastrointestinal and neurological disturbances. We assessed the activity of the most potent congener, Pacific ciguatoxin-1 (P-CTX-1), on Na V 1.1–1.9 using imaging and electrophysiological approaches. Although P-CTX-1 is essentially a non-selective Na V toxin and shifted the voltage-dependence of activation to more hyperpolarising potentials at all Na V subtypes, an increase in the inactivation time constant was observed only at Na V 1.8, while the slope factor of the conductance-voltage curves was significantly increased for Na V 1.7 and peak current was significantly increased for Na V 1.6. Accordingly, P-CTX-1-induced visceral and cutaneous pain behaviours were significantly decreased after pharmacological inhibition of Na V 1.8 and the tetrodotoxin-sensitive isoforms Na V 1.7 and Na V 1.6, respectively. The contribution of these isoforms to excitability of peripheral C- and A-fibre sensory neurons, confirmed using murine skin and visceral single-fibre recordings, reflects the expression pattern of Na V isoforms in peripheral sensory neurons and their contribution to membrane depolarisation, action potential initiation and propagation.

Mechanisms of Spinal Cord Plasticity in Rodent Models of Acute and Post-Colitis Visceral Hypersensitivity

Publisher: Springer International Publishing

Date: 2023

DOI: 10.1007/978-3-031-25702-5_14

Translating Colonic Sensory Afferent Peripheral Mechanosensitivity into the Spinal Cord Dorsal Horn

Publisher: Springer International Publishing

Date: 2023

DOI: 10.1007/978-3-031-25702-5_13

Chronic linaclotide treatment reduces colitis-induced neuroplasticity and reverses persistent bladder dysfunction.

Publisher: American Society for Clinical Investigation

Date: 04-10-2018

DOI: 10.1172/JCI.INSIGHT.121841

Extrinsic Sensory Afferent Nerves Innervating the Gastrointestinal Tract in Health and Disease

Publisher: Elsevier

Date: 2018

DOI: 10.1016/B978-0-12-809954-4.00017-7

The Ion Channel TRPA1 Is Required for Normal Mechanosensation and Is Modulated by Algesic Stimuli

Publisher: Elsevier BV

Date: 12-2009

DOI: 10.1053/J.GASTRO.2009.07.048

Gastric vagal afferent modulation by leptin is influenced by food intake status

Publisher: Wiley

Date: 18-02-2013

DOI: 10.1113/JPHYSIOL.2012.247577

Effects and sites of action of a M1 receptor positive allosteric modulator on colonic motility in rats and dogs compared with 5-HT4 agonism and cholinesterase inhibition

Publisher: Wiley

Date: 26-04-2020

DOI: 10.1111/NMO.13866

Activation of colo-rectal high-threshold afferent nerves by Interleukin-2 is tetrodotoxin-sensitive and upregulated in a mouse model of chronic visceral hypersensitivity.

Publisher: Wiley

Date: 14-10-2016

DOI: 10.1111/NMO.12696

Abstract: Chronic visceral pain is a defining feature of irritable bowel syndrome (IBS). IBS patients often show alterations in innate and adaptive immune function which may contribute to symptoms. Immune mediators are known to modulate the activity of viscero-sensory afferent nerves, but the focus has been on the innate immune system. Interleukin-2 (IL-2) is primarily associated with adaptive immune responses but its effects on colo-rectal afferent function in health or disease are unknown. Myeloperoxidase (MPO) activity determined the extent of inflammation in health, acute trinitrobenzene-sulfonic acid (TNBS) colitis, and in our post-TNBS colitis model of chronic visceral hypersensitivity (CVH). The functional effects of IL-2 on high-threshold colo-rectal afferents and the expression of IL-2R and NaV 1.7 mRNA in colo-rectal dorsal root ganglia (DRG) neurons were compared between healthy and CVH mice. MPO activity was increased during acute colitis, but subsided to levels comparable to health in CVH mice. IL-2 caused direct excitation of colo-rectal afferents that was blocked by tetrodotoxin. IL-2 did not affect afferent mechanosensitivity in health or CVH. However, an increased proportion of afferents responded directly to IL-2 in CVH mice compared with controls (73% vs 33% p < 0.05), and the abundance of IL-2R and NaV 1.7 mRNA was increased 3.5- and 2-fold (p < 0.001 for both) in colo-rectal DRG neurons. IL-2, an immune mediator from the adaptive arm of the immune response, affects colo-rectal afferent function, indicating these effects are not restricted to innate immune mediators. Colo-rectal afferent sensitivity to IL-2 is increased long after healing from inflammation.

Activation of MrgprA3 and MrgprC11 on bladder-innervating afferents induces peripheral and central hypersensitivity to bladder distension

Publisher: Society for Neuroscience

Date: 16-03-2021

DOI: 10.1523/JNEUROSCI.0033-21.2021

Abstract: Understanding the sensory mechanisms innervating the bladder is paramount to developing efficacious treatments for chronic bladder hypersensitivity conditions. The contribution of Mas-gene-related G protein-coupled receptors (Mrgpr) to bladder signaling is currently unknown. Using male and female mice, we show with single-cell RT-PCR that subpopulations of DRG neurons innervating the mouse bladder express MrgprA3 (14%) and MrgprC11 (38%), either in idually or in combination, with high levels of coexpression with Trpv1 (81%-89%). Calcium imaging studies demonstrated MrgprA3 and MrgprC11 agonists (chloroquine, BAM8-22, and neuropeptide FF) activated subpopulations of bladder-innervating DRG neurons, showing functional evidence of coexpression between MrgprA3, MrgprC11, and TRPV1. In ex vivo bladder-nerve preparations, chloroquine, BAM8-22, and neuropeptide FF all evoked mechanical hypersensitivity in subpopulations (20%-41%) of bladder afferents. These effects were absent in recordings from Mrgpr-cluster Δ −/− mice. In vitro whole-cell patch-cl recordings showed that application of an MrgprA3/C11 agonist mixture induced neuronal hyperexcitability in 44% of bladder-innervating DRG neurons. Finally, in vivo instillation of an MrgprA3/C11 agonist mixture into the bladder of WT mice induced a significant activation of dorsal horn neurons within the lumbosacral spinal cord, as quantified by pERK immunoreactivity. This MrgprA3/C11 agonist-induced activation was particularly apparent within the superficial dorsal horn and the sacral parasympathetic nuclei of WT, but not Mrgpr-cluster Δ −/− mice. This study demonstrates, for the first time, functional expression of MrgprA3 and MrgprC11 in bladder afferents. Activation of these receptors triggers hypersensitivity to distension, a critically valuable factor for therapeutic target development. SIGNIFICANCE STATEMENT Determining how bladder afferents become sensitized is the first step in finding effective treatments for common urological disorders such as overactive bladder and interstitial cystitis/bladder pain syndrome. Here we show that two of the key receptors, MrgprA3 and MrgprC11, that mediate itch from the skin are also expressed on afferents innervating the bladder. Activation of these receptors results in sensitization of bladder afferents, resulting in sensory signals being sent into the spinal cord that prematurely indicate bladder fullness. Targeting bladder afferents expressing MrgprA3 or MrgprC11 and preventing their sensitization may provide a novel approach for treating overactive bladder and interstitial cystitis/bladder pain syndrome.

Guanylate cyclase-C agonists as peripherally acting treatments of chronic visceral pain

Publisher: Elsevier BV

Date: 02-2022

DOI: 10.1016/J.TIPS.2021.11.002

Optimizing arterial 18F-sodium fluoride positron emission tomography analysis

Publisher: Springer Science and Business Media LLC

Date: 23-03-2019

DOI: 10.1007/S12350-019-01992-6

TGR5 agonists induce peripheral and central hypersensitivity to bladder distension

Publisher: Springer Science and Business Media LLC

Date: 15-06-2022

DOI: 10.1038/S41598-022-14195-W

Abstract: The mechanisms underlying chronic bladder conditions such as interstitial cystitis/bladder pain syndrome (IC/BPS) and overactive bladder syndrome (OAB) are incompletely understood. However, targeting specific receptors mediating neuronal sensitivity to specific stimuli is an emerging treatment strategy. Recently, irritant-sensing receptors including the bile acid receptor TGR5, have been identified within the viscera and are thought to play a key role in neuronal hypersensitivity. Here, in mice, we identify mRNA expression of TGR5 ( Gpbar1 ) in all layers of the bladder as well as in the lumbosacral dorsal root ganglia (DRG) and in isolated bladder-innervating DRG neurons. In bladder-innervating DRG neurons Gpbar1 mRNA was 100% co-expressed with Trpv1 and 30% co-expressed with Trpa1 . In vitro live-cell calcium imaging of bladder-innervating DRG neurons showed direct activation of a sub-population of bladder-innervating DRG neurons with the synthetic TGR5 agonist CCDC, which was diminished in Trpv1 −/− but not Trpa1 −/− DRG neurons. CCDC also activated a small percentage of non-neuronal cells. Using an ex vivo mouse bladder afferent recording preparation we show intravesical application of endogenous (5α-pregnan-3β-ol-20-one sulphate, Pg5α) and synthetic (CCDC) TGR5 agonists enhanced afferent mechanosensitivity to bladder distension. Correspondingly, in vivo intravesical administration of CCDC increased the number of spinal dorsal horn neurons that were activated by bladder distension. The enhanced mechanosensitivity induced by CCDC ex vivo and in vivo was absent using Gpbar1 −/− mice. Together, these results indicate a role for the TGR5 receptor in mediating bladder afferent hypersensitivity to distension and thus may be important to the symptoms associated with IC/BPS and OAB.

Immunohistochemical localisation of pre-synaptic muscarinic receptor subtype-2 (M2r) in the enteric nervous system of guinea-pig ileum

Publisher: Springer Science and Business Media LLC

Date: 05-02-2008

DOI: 10.1007/S00441-007-0533-0

Abstract: The cholinergic muscarinic 2 receptor (M2r) is known to be present on smooth muscle cells in the intestine. Pharmacological studies also suggest that M2rs regulate transmitter release from nerves in the enteric nervous system. This study localised M2rs in the guinea-pig ileum using different antibodies and fluorescence immunohistochemistry. Double labelling with antibodies against neurochemical markers was used to identify the type of nerves bearing M2r. Guinea-pig ileum were fixed, prepared for sections and wholemounts and incubated with antisera against the M2r sequence. Tissue was double labelled with antibodies against neuronal nitric oxide synthase (nNOS), common choline acetyltransferase (cChAT), substance P (SP), synaptophysin and vesicular acetylcholine transporter (VAChT). Immunofluorescence was viewed using confocal microscopy. Abundant M2r-immunoreactivity (IR) was present on the surface of circular and longitudinal smooth muscle cells. M2r-IR was present in many but not all nerve fibres in the circular muscle and ganglia. M2r-IR was present in VAChT-IR and cChAT-IR cholinergic nerve fibres and SP-IR nerve fibres in the myenteric ganglia and submucosal ganglia. M2r-IR was present on a few nNOS-IR nerve fibres and around nNOS-IR neurons in the myenteric ganglia. In the circular muscle and deep muscular plexus, M2r-IR was present in many VAChT-IR and SP-IR nerve fibres and in few nNOS-IR nerves. M2rs are not only present on muscle cells in the intestine, but also on nerve fibres. M2rs may mediate cholinergic reflexes via their location on muscle and also via neural transmission. The pre-synaptic location supports pharmacological studies suggesting M2rs mediate neurotransmitter release from nerve fibres. The presence of M2rs on VAChT-IR, SP-IR and nNOS-IR-containing nerve fibres suggests M2rs may regulate ACh, SP and nitric oxide release.

A mouse model of endometriosis that displays vaginal, colon, cutaneous, and bladder sensory comorbidities

Publisher: Wiley

Date: 22-03-2021

DOI: 10.1096/FJ.202002441R

Increased κ-opioid receptor expression and function during chronic visceral hypersensitivity

Publisher: BMJ

Date: 27-11-2014

DOI: 10.1136/GUTJNL-2013-306240

Low Endothelial Shear Stress Is Associated With High-Risk Coronary Plaque Features and Microcalcification Activity

Publisher: Elsevier BV

Date: 11-2021

DOI: 10.1016/J.JCMG.2021.06.016

Fall in density, but not number of myenteric neurons and circular muscle nerve fibres in guinea‐pig colon with ageing

Publisher: Wiley

Date: 07-09-2009

DOI: 10.1111/J.1365-2982.2009.01349.X

Abstract: In guinea-pig ileum, ageing has been associated with a decrease in enteric neurons. This study examined guinea-pig colon and measured changes in gut dimensions, neuron size, density and ganglionic area. Changes in motor nerve fibres in the circular muscle were also measured. Myenteric neurons in whole-mount preparations of mid-colon from 2-week, 6-month, and 2-year-old guinea-pigs were labelled immunohistochemically with the neuronal marker human neuronal protein HuC/HuD, and numbers of neurons mm(-2), neuronal size, ganglionic area mm(-2), gut length, circumference and muscle thickness were measured. Corrected numbers of neurons mm(-2) and ganglionic area mm(-2) accounting for growth of the colon were calculated. Additionally, nerve fibres in circular muscle cross-sections were labelled with antibodies against nitric oxide synthase (NOS) and substance P (SP) and the density of nerve fibres in circular muscle was measured. The numbers of neurons mm(-2) decreased by 56% (from 2 weeks to 2 years) with no change in neuron size. Total neuron numbers decreased by 19% (P = 0.14) when adjusted for changes in length and circumference with age. The percentage area of NOS- and SP-immunoreactive (IR) nerve fibres in the circular muscle decreased (P < 0.001), but the total area of NOS and SP-IR nerve fibres increased (P < 0.01) due to an age-related increase in muscle thickness. The density of myenteric neurons in guinea-pig mid-colon halved from 2 weeks to 2 years, but when the increase in colon dimensions was considered, the number of neurons decreased by only 19%. The percentage area of motor nerve fibres in the circular muscle decreased with no change in total volume of nerve fibres.

Identifying the ion channels responsible for signaling gastro-intestinal based pain

Publisher: MDPI AG

Date: 26-08-2010

DOI: 10.3390/PH3092768

TRPA1 contributes to specific mechanically activated currents and sensory neuron mechanical hypersensitivity

Publisher: Wiley

Date: 15-07-2011

DOI: 10.1113/JPHYSIOL.2011.206789

High affinity choline transporter immunoreactivity in rat ileum myenteric nerves

Publisher: Springer Science and Business Media LLC

Date: 09-11-2006

DOI: 10.1007/S00441-006-0332-Z

Abstract: Recently, an antibody against the choline transporter (CHT), an essential molecule involved in ACh uptake, was used to label cholinergic nerves in the central nervous system however, the enteric nervous system (ENS) was not examined. The present study localised CHT immunoreactivity (CHT-IR) within the rat ileum ENS and determined whether it colocalised with immunoreactivity for markers of cholinergic, tachykinergic and nitrergic circuitry. Segments of rat ileum were fixed, prepared for sectioning or whole-mounts and incubated with anti-CHT antisera followed by a fluorescent secondary antibody. S les were double-labelled with antibodies to nitric oxide synthase, substance P (SP), common choline acetyltransferase (cChAT) and vesicular acetylcholine transporter (VAChT). CHT-IR was present in varicosities of nerve fibres in the myenteric plexus and muscle layers of rat ileum. In the myenteric ganglia, CHT-IR was found in nerve fibres and the cytoplasm of some nerve cell bodies. In the myenteric ganglia, no CHT/cChAT-immunoreactive neurons were present. A small number of CHT/SP-immunoreactive neurons and CHT/SP-immunoreactive nerve fibres clustered around unlabelled neurons. CHT-IR colocalised with VAChT-IR in the myenteric plexus but only half of the CHT-immunoreactive myenteric nerve fibres were VAChT-immunoreactive and half of VAChT-immunoreactive fibres were CHT-immunoreactive. In the circular muscle, 75% of CHT-immunoreactive fibres were VAChT-immunoreactive. Thus, the anti-CHT antiserum labels neurons and nerve fibres in the rat ENS. It does not label cholinergic cChAT-immunoreactive neurons, although it does immunostain cholinergic VAChT-immunoreactive nerve fibres and a population of nerves that are not VAChT-immunoreactive.

Acute colitis chronically alters immune infiltration mechanisms and sensory neuro-immune interactions.

Publisher: Elsevier BV

Date: 02-2017

DOI: 10.1016/J.BBI.2016.11.015

Abstract: Little is understood regarding how disease progression alters immune and sensory nerve function in colitis. We investigated how acute colitis chronically alters immune recruitment and the impact this has on re-activated colitis. To understand the impact of disease progress on sensory systems we investigated the mechanisms underlying altered colonic neuro-immune interactions after acute colitis. Inflammation was compared in mouse models of health, acute tri-nitrobenzene sulphonic acid (TNBS) colitis, Remission and Reactivated colitis. Cytokine concentrations were compared by ELISA in-situ and in explanted colon tissue. Colonic infiltration by CD11b/F4-80 macrophage, CD4 T Colonic damage, MPO activity, macrophage infiltration, IL-1β and IL-6 concentrations were lower in Reactivated compared to Acute colitis. T Acute colitis persistently alters immune responses and afferent nerve signalling pathways to successive episodes of colitis. These findings highlight the complexity of viscero-sensory neuro-immune interactions in painful remitting and relapsing diseases.

Contribution of membrane receptor signalling to chronic visceral pain

Publisher: Elsevier BV

Date: 05-2018

DOI: 10.1016/J.BIOCEL.2018.02.017

Abstract: Irritable bowel syndrome and inflammatory bowel disease are major forms of chronic visceral pain, which affect over 15% of the global population. In order to identify new therapies, it is important to understand the underlying causes of chronic visceral pain. This review provides recent evidence demonstrating that inflammation or infection of the gastrointestinal tract triggers specific changes in the neuronal excitability of sensory pathways responsible for the transmission of nociceptive information from the periphery to the central nervous system. Specific changes in the expression and function of a variety of ion channels and receptors have been documented in inflammatory and chronic visceral pain conditions relevant to irritable bowel syndrome and inflammatory bowel disease. An increase in pro-nociceptive mechanisms enhances peripheral drive from the viscera and provides an underlying basis for enhanced nociceptive signalling during chronic visceral pain states. Recent evidence also highlights increases in anti-nociceptive mechanisms in models of chronic visceral pain, which present novel targets for pharmacological treatment of this condition.

Cyclic analogues of α-conotoxin Vc1.1 inhibit colonic nociceptors and provide analgesia in a mouse model of chronic abdominal pain

Publisher: Wiley

Date: 13-02-2018

DOI: 10.1111/BPH.14115

Pruritogenic mechanisms and gut sensation: putting the “irritant” into irritable bowel syndrome

Publisher: American Physiological Society

Date: 06-2021

DOI: 10.1152/AJPGI.00331.2020

Abstract: Chronic abdominal pain is a common clinical condition experienced by patients with irritable bowel syndrome (IBS). A general lack of suitable treatment options for the management of visceral pain is the major contributing factor to the debilitating nature of the disease. Understanding the underlying causes of chronic visceral pain is pivotal to identifying new effective therapies for IBS. This review provides the current evidence, demonstrating that mediators and receptors that induce itch in the skin also act as “gut irritants” in the gastrointestinal tract. Activation of these receptors triggers specific changes in the neuronal excitability of sensory pathways responsible for the transmission of nociceptive information from the periphery to the central nervous system leading to visceral hypersensitivity and visceral pain. Accumulating evidence points to significant roles of irritant mediators and their receptors in visceral hypersensitivity and thus constitutes potential targets for the development of more effective therapeutic options for IBS.

Extracellular CGMP Reduces the Excitability of Sensory Dorsal Root Ganglion Neurons via an Extracellular Mechanism

Publisher: Elsevier BV

Date: 04-2017

DOI: 10.1016/S0016-5085(17)30847-8

Experimental colitis models

Publisher: Humana Press

Date: 2012

DOI: 10.1007/978-1-62703-095-3_23

Tetrodotoxin-sensitive voltage-gated sodium channels regulate bladder afferent responses to distension

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 27-08-2018

DOI: 10.1097/J.PAIN.0000000000001368

Abstract: Interstitial cystitis/bladder pain syndrome (IC/BPS) is a prevalent, chronic bladder disorder that negatively impacts the quality of life for ∼5% of the western population. Hypersensitivity of mechanosensory afferents embedded within the bladder wall is considered a key component in mediating IC/BPS symptoms. Bladder infusion of voltage-gated sodium (Na v ) channel blockers show clinical efficacy in treating IC/BPS symptoms however, the current repertoire of Na v channels expressed by and contributing to bladder afferent function is unknown. We used single-cell reverse-transcription polymerase chain reaction of retrogradely traced bladder-innervating dorsal root ganglia (DRG) neurons to determine the expression profile of Na v channels, and patch-cl recordings to characterise the contribution of tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na v channels to total sodium current and neuronal excitability. We determined the TTX-S and TTX-R contribution to mechanosensitive bladder afferent responses ex vivo and spinal dorsal horn activation in vivo. Single-cell reverse-transcription polymerase chain reaction of bladder-innervating DRG neurons revealed significant heterogeneity in Na v channel coexpression patterns. However, TTX-S Na v channels contribute the vast majority of the total sodium current density and regulate the neuronal excitability of bladder DRG neurons. Furthermore, TTX-S Na v channels mediate almost all bladder afferent responses to distension. In vivo intrabladder infusion of TTX significantly reduces activation of dorsal horn neurons within the spinal cord to bladder distension. These data provide the first comprehensive analysis of Na v channel expression within sensory afferents innervating the bladder. They also demonstrate an essential role for TTX-S Na v channel regulation of bladder-innervating DRG neuroexcitability, bladder afferent responses to distension, and nociceptive signalling to the spinal cord.

Sensory neuro-immune interactions differ between Irritable Bowel Syndrome subtypes

Publisher: BMJ

Date: 05-07-2013

DOI: 10.1136/GUTJNL-2011-301856

Abstract: The gut is a major site of contact between immune and sensory systems and evidence suggests that patients with irritable bowel syndrome (IBS) have immune dysfunction. Here we show how this dysfunction differs between major IBS subgroups and how immunocytes communicate with sensory nerves. Peripheral blood mononuclear cell supernatants from 20 diarrhoea predominant IBS (D-IBS) patients, 15 constipation predominant IBS (C-IBS) patients and 36 healthy subjects were applied to mouse colonic sensory nerves and effects on mechanosensitivity assessed. Cytokine/chemokine concentration in the supernatants was assessed by proteomic analysis and correlated with abdominal symptoms, and expression of cytokine receptors evaluated in colonic dorsal root ganglia neurons. We then determined the effects of specific cytokines on colonic afferents. D-IBS supernatants caused mechanical hypersensitivity of mouse colonic afferent endings, which was reduced by infliximab. C-IBS supernatants did not, but occasionally elevated basal discharge. Supernatants of healthy subjects inhibited afferent mechanosensitivity via an opioidergic mechanism. Several cytokines were elevated in IBS supernatants, and levels correlated with pain frequency and intensity in patients. Visceral afferents expressed receptors for four cytokines: IL-1β, IL-6, IL-10 and TNF-α. TNF-α most effectively caused mechanical hypersensitivity which was blocked by a transient receptor potential channel TRPA1 antagonist. IL-1β elevated basal firing, and this was lost after tetrodotoxin blockade of sodium channels. Distinct patterns of immune dysfunction and interaction with sensory pathways occur in different patient groups and through different intracellular pathways. Our results indicate IBS patient subgroups would benefit from selective targeting of the immune system.

The impact of non‐vitamin K antagonist oral anticoagulants (NOACs) on anticoagulation therapy in rural Australia

Publisher: AMPCo

Date: 2018

DOI: 10.5694/MJA17.00132

Abstract: To determine the use of different anticoagulation therapies in rural Western Australia to establish whether remoteness from health care services affects the choice of anticoagulation therapy to gather preliminary data on anticoagulation therapy safety and efficacy. Retrospective cohort study of patients hospitalised with a principal diagnosis of atrial fibrillation/flutter (AF) or venous thromboembolism (VTE) during 2014-2015. Four hospitals serving two-thirds of the rural population of Western Australia. 609 patients with an indication for anticoagulation therapy recorded in their hospital discharge summary for index admission. Prescribing rates of anticoagulation therapies by indication for anticoagulation and distance of patient residence from their hospital. The primary safety outcome was re-hospitalisation with a major or clinically relevant non-major bleeding event the primary lack-of-efficacy outcome was re-hospitalisation for a thromboembolic event. The overall rates of prescription of NOACs and warfarin were similar (34% v 33%). A NOAC was prescribed more often than warfarin for patients with AF (56.0% v 42.2% of those who received an anticoagulant P < 0.001), but less often for patients with VTE (29% v 48% P < 0.001). Warfarin was prescribed for 38% of patients who lived locally, a NOAC for 31% (P = 0.013) for non-local patients, the respective proportions were 29% and 36% (P = 0.08). 69% of patients with AF and a CHA2DS2-VASc score ≥ 1 were prescribed anticoagulation therapy. Patients treated with NOACs had fewer bleeding events than patients treated with warfarin (nine events [4%] v 20 events [10%] P = 0.027). In rural WA, about one-third of patients with an indication for anticoagulation therapy receive NOACs, but one-third of patients with AF and at risk of stroke received no anticoagulant therapy, and may benefit from NOAC therapy.

α-Conotoxin Vc1.1 inhibits human dorsal root ganglion neuroexcitability and mouse colonic nociception via GABAB receptors.

Publisher: BMJ

Date: 17-02-2016

DOI: 10.1136/GUTJNL-2015-310971

In search of the vulnerable patient or the vulnerable plaque: 18F-sodium fluoride positron emission tomography for cardiovascular risk stratification

Publisher: Springer Science and Business Media LLC

Date: 03-04-0007

DOI: 10.1007/S12350-018-1360-2

Abstract: Cardiovascular disease (CVD) remains a leading cause of death. Preventative therapies that reduce CVD are most effective when targeted to in iduals at high risk. Current risk stratification tools have only modest prognostic capabilities, resulting in over-treatment of low-risk in iduals and under-treatment of high-risk in iduals. Improved methods of CVD risk stratification are required. Molecular imaging offers a novel approach to CVD risk stratification. In particular,

Coronary artery 18F-NaF PET analysis with the use of an elastic motion correction software

Publisher: Springer Science and Business Media LLC

Date: 25-01-2023

DOI: 10.1007/S12350-018-01587-7

Abstract: 18F-Sodium Fluoride Positron Emission Tomography (18F-NaF PET) is a novel molecular imaging modality with promise for use as a risk stratification tool in cardiovascular disease. There are limitations in the analysis of small and rapidly moving coronary arteries using traditional PET technology. We aimed to validate the use of a motion correction algorithm (eMoco) on coronary 18F-NaF PET outcome parameters. Patients admitted with an acute coronary syndrome underwent 18F-NaF PET and computed tomography coronary angiography. 18F-NaF PET data were analyzed using a diastolic reconstruction, an ungated reconstruction and the eMoco reconstruction. Twenty patients underwent 18F-NaF PET imaging and 17 patients had at least one positive lesion that could be used to compare PET reconstruction datasets. eMoco improved noise (the coefficient of variation of the blood pool radiotracer activity) compared to the diastolic dataset (0.09 [0.07 to 0.12] vs 0.14[0.11 to 0.17], p < .001) and marginally improved coronary lesion maximum tissue-to-background ratios compared to the ungated dataset (1.33 [1.05 to 1.48]vs 1.29 [1.04 to 1.40], p = .011). In this pilot dataset, the eMoco reconstruction algorithm for motion correction appears to have potential in improving coronary analysis of 18F-NaF PET by reducing noise and increasing maximum counts. Further testing in a larger patient dataset is warranted.

Clodronate Treatment Prevents Vaginal Hypersensitivity in a Mouse Model of Vestibulodynia

Publisher: Frontiers Media SA

Date: 18-01-2022

DOI: 10.3389/FCIMB.2021.784972

Abstract: Improved understanding of vestibulodynia pathophysiology is required to develop appropriately targeted treatments. Established features include vulvovaginal hyperinnervation, increased nociceptive signalling and hypersensitivity. Emerging evidence indicates macrophage-neuron signalling contributes to chronic pain pathophysiology. Macrophages are broadly classified as M1 or M2, demonstrating pro-nociceptive or anti-nociceptive effects respectively. This study investigates the impact of clodronate liposomes, a macrophage depleting agent, on nociceptive signalling in a mouse model of vestibulodynia. Microinjection of complete Freund’s adjuvant (CFA) at the vaginal introitus induced mild chronic inflammation in C57Bl/6J mice. A subgroup was treated with the macrophage depleting agent clodronate. Control mice received saline. After 7 days, immunolabelling for PGP9.5, F4/80+CD11c+ and F4/80+CD206+ was used to compare innervation density and presence of M1 and M2 macrophages respectively in experimental groups. Nociceptive signalling evoked by vaginal distension was assessed using immunolabelling for phosphorylated MAP extracellular signal-related kinase (pERK) in spinal cord sections. Hyperalgesia was assessed by visceromotor response to graded vaginal distension. CFA led to increased vaginal innervation (p & 0.05), increased pERK-immunoreactive spinal cord dorsal horn neurons evoked by vaginal-distension (p & 0.01) and enhanced visceromotor responses compared control mice (p & 0.01). Clodronate did not reduce vaginal hyperinnervation but significantly reduced the abundance of M1 and M2 vaginal macrophages and restored vaginal nociceptive signalling and vaginal sensitivity to that of healthy control animals. We have developed a robust mouse model of vestibulodynia that demonstrates vaginal hyperinnervation, enhanced nociceptive signalling, hyperalgesia and allodynia. Macrophages contribute to hypersensitivity in this model. Macrophage-sensory neuron signalling pathways may present useful pathophysiological targets.

Voltage-gated sodium channels: (NaV)igating the field to determine their contribution to visceral nociception.

Publisher: Wiley

Date: 06-02-2018

DOI: 10.1113/JP273461

Immunohistochemical localisation of cholinergic muscarinic receptor subtype 1 (M1r) in the guinea pig and human enteric nervous system

Publisher: Elsevier BV

Date: 07-2007

DOI: 10.1016/J.JCHEMNEU.2007.03.001

Abstract: Little is known regarding the location of cholinergic muscarinic receptor 1 (M1r) in the ENS, even though physiological data suggest that M1rs are central to cholinergic neurotransmission. This study localised M1rs in the ENS of the guinea pig ileum and human colon using fluorescence immunohistochemistry and RT-PCR in human colon. Double labelling using antibodies against neurochemical markers was used to identify neuron subytpes bearing M1r. M1r immunoreactivity (IR) was present on neurons in the myenteric and submucosal ganglia. The two antibodies gave similar M1r-IR patterns and M1r-IR was abolished upon antibody preabsorption. M1r-IR was present on cholinergic and nNOS-IR nerve cell bodies in both guinea pig and human myenteric neurons. Presynaptic M1r-IR was present on NOS-IR and VAChT-IR nerve fibres in the circular muscle in the human colon. In the submucosal ganglia, M1r-IR was present on a population of neurons that contained cChAT-IR, but did not contain NPY-IR or calretinin-IR. M1r-IR was present on endothelial cells of blood vessels in the submucosal plexus. The localisation of M1r-IR in the guinea pig and human ENS shown in this study agrees with physiological studies. M1r-IR in cholinergic and nitrergic neurons and nerve fibres indicate that M1rs have a role in both cholinergic and nitrergic transmission. M1r-IR present in submucosal neurons suggests a role in mediating acetylcholine's effect on submucosal sensory and secretomotor/vasodilator neurons. M1r-IR present on blood vessel endothelial cells suggests that M1rs may also mediate acetylcholine's direct effect on vasoactivation.

TRP channels in visceral pain

Publisher: Bentham Science Publishers Ltd.

Date: 08-03-2013

DOI: 10.2174/1876386301306010023

Abstract: Visceral pain is both different and similar to somatic pain - different in being poorly localized and usually referred elsewhere to the body wall, but similar in many of the molecular mechanisms it employs (like TRP channels) and the specialization of afferent endings to detect painful stimuli. TRPV1 is sensitive to low pH. pH is lowest in gastric juice, which may cause severe pain when exposed to the oesophageal mucosa, and probably works via TRPV1. TRPV1 is found in afferent fibres throughout the viscera, and the TRPV1 agonist capsaicin can recapitulate symptoms experienced in disease. TRPV1 is also involved in normal mechanosensory function in the gut. Roles for TRPV4 and TRPA1 have also been described in visceral afferents, and TRPV4 is highly enriched in them, where it plays a major role in both mechanonociception and chemonociception. It may provide a visceral-specific nociceptor target for drug development. TRPA1 is also involved in mechano-and chemosensory function, but not as selectively as TRPV4. TRPA1 is colocalized with TRPV1 in visceral afferents, where they influence each other's function. Another modulator of TRPV1 is the cool/mint receptor TRPM8, which, when activated can abrogate responses mediated via TRPV1, suggesting that TRPM8 agonists may provide analgesia via this pathway. In all, the viscera are rich in TRP channel targets on nociceptive neurones which we hope will provide opportunities for therapeutic analgesia.

Immunoreactivity for high-affinity choline transporter colocalises with VAChT in human enteric nervous system

Publisher: Springer Science and Business Media LLC

Date: 21-05-2010

DOI: 10.1007/S00441-010-0981-9

Abstract: Cholinergic nerves are identified by labelling molecules in the ACh synthesis, release and destruction pathway. Recently, antibodies against another molecule in this pathway have been developed. Choline reuptake at the synapse occurs via the high-affinity choline transporter (CHT1). CHT1 immunoreactivity is present in cholinergic nerve fibres containing vesicular acetylcholine transporter (VAChT) in the human and rat central nervous system and rat enteric nervous system. We have examined whether CHT1 immunoreactivity is present in nerve fibres in human intestine and whether it is colocalised with markers of cholinergic, tachykinergic or nitrergic circuitry. Human ileum and colon were fixed, sectioned and processed for fluorescence immunohistochemistry with antibodies against CHT1, class III beta-tubulin (TUJ1), synaptophysin, common choline acetyl-transferase (cChAT), VAChT, nitric oxide synthase (NOS), substance P (SP) and vasoactive intestinal peptide (VIP). CHT1 immunoreactivity was present in many nerve fibres in the circular and longitudinal muscle, myenteric and submucosal ganglia, submucosa and mucosa in human colon and ileum and colocalised with immunoreactivity for TUJ1 and synaptophysin confirming its presence in nerve fibres. In nerve fibres in myenteric ganglia and muscle, CHT1 immunoreactivity colocalised with immunoreactivity for VAChT and cChAT. Some colocalisation occurred with SP immunoreactivity, but little with immunoreactivity for VIP or NOS. In the mucosa, CHT1 immunoreactivity colocalised with that for VIP and SP in nerve fibres and was also present in vascular nerve fibres in the submucosa and on epithelial cells on the luminal border of crypts. The colocalisation of CHT1 immunoreactivity with VAChT immunoreactivity in cholinergic enteric nerves in the human bowel thus suggests that CHT1 represents another marker of cholinergic nerves.

Histamine induces peripheral and central hypersensitivity to bladder distension via the histamine H1 receptor and TRPV1

Publisher: American Physiological Society

Date: 02-2020

DOI: 10.1152/AJPRENAL.00435.2019

Abstract: Interstitial cystitis/bladder pain syndrome (IC/BPS) is a common chronic pelvic disorder with sensory symptoms of urinary urgency, frequency, and pain, indicating a key role for hypersensitivity of bladder-innervating sensory neurons. The inflammatory mast cell mediator histamine has long been implicated in IC/BPS, yet the direct interactions between histamine and bladder afferents remain unclear. In the present study, we show, using a mouse ex vivo bladder afferent preparation, that intravesical histamine enhanced the mechanosensitivity of subpopulations of afferents to bladder distension. Histamine also recruited “silent afferents” that were previously unresponsive to bladder distension. Furthermore, in vivo intravesical histamine enhanced activation of dorsal horn neurons within the lumbosacral spinal cord, indicating increased afferent signaling in the central nervous system. Quantitative RT-PCR revealed significant expression of histamine receptor subtypes ( Hrh1– Hrh3) in mouse lumbosacral dorsal root ganglia (DRG), bladder detrusor smooth muscle, mucosa, and isolated urothelial cells. In DRG, Hrh1 was the most abundantly expressed. Acute histamine exposure evoked Ca 2+ influx in select populations of DRG neurons but did not elicit calcium transients in isolated primary urothelial cells. Histamine-induced mechanical hypersensitivity ex vivo was abolished in the presence of the histamine H 1 receptor antagonist pyrilamine and was not present in preparations from mice lacking transient receptor potential vanilloid 1 (TRPV1). Together, these results indicate that histamine enhances the sensitivity of bladder afferents to distension via interactions with histamine H 1 receptor and TRPV1. This hypersensitivity translates to increased sensory input and activation in the spinal cord, which may underlie the symptoms of bladder hypersensitivity and pain experienced in IC/BPS.

Flinders University

Location: Australia

View Organisation

University Of Adelaide

Location: Australia

View Organisation

University Of Melbourne

Location: Australia

View Organisation

Mount Evelyn Primary School

Location: Australia

View Organisation

Murdoch Childrens Research Institute

Location: Australia

View Organisation

Hanson Institute

Location: Australia

View Organisation

Monbulk College

Location: Australia

View Organisation

Central Pathways Regulating Visceral Pain

Start Date: 2018

End Date: 2020

Funder: Australian Research Council

Mapping Sites Of Visceral Convergence Connecting The Colon And Bladder

Start Date: 2022

End Date: 2024

Funder: Australian Research Council

Discovery Projects - Grant ID: DP220101269

Start Date: 04-2022

End Date: 04-2025

Amount: $456,249.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP180101395

Start Date: 03-2018

End Date: 12-2021

Amount: $331,383.00

Funder: Australian Research Council

Discovery Early Career Researcher Award - Grant ID: DE130100223

Start Date: 2013

End Date: 03-2018

Amount: $375,000.00

Funder: Australian Research Council