ORCID Profile
0000-0001-6007-5192
Current Organisations
UNSW Sydney
,
Macquarie University
,
Blooms the Chemist
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Publisher: Wiley
Date: 27-01-2022
DOI: 10.1002/PRP2.921
Abstract: Tapentadol is a centrally acting analgesic with a dual mechanism of action. It acts as an agonist at the µ receptor and inhibitor of noradrenaline reuptake. Clinical trials suggest similar analgesic efficacy of tapentadol, oxycodone, and morphine in acute and chronic pain. Given the limited information about the molecular actions of tapentadol at the µ receptor, we investigated the intrinsic efficacy of tapentadol and compared it with other opioids. β‐chlornaltrexamine (β‐CNA, 100 nM, 20 min) was used to deplete spare receptors in AtT20 cells stably transfected with human µ receptor wild‐type (WT). Opioid‐mediated changes in membrane potential were measured in real‐time using a membrane potential‐sensitive fluorescent dye. Using Black and Leff’s operational model, intrinsic efficacy relative to DAMGO was calculated for each opioid. Tapentadol (0.05 ± 0.01) activated the GIRK channel with lesser intrinsic efficacy than morphine (0.17 ± 0.02) and oxycodone (0.16 ± 0.02). We further assessed the signaling of tapentadol in the common µ receptor variants (N40D and A6V) which are associated with altered receptor signaling. We found no difference in the response of tapentadol between these receptor variants.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 31-03-2020
DOI: 10.1126/SCISIGNAL.AAZ3140
Abstract: Low intrinsic efficacy can explain the reduced side effects of apparently biased μ-opioid receptor agonists.
Publisher: Wiley
Date: 09-08-2023
Abstract: Combination drug therapy addresses the auxiliary cancer pathways of the tumor progression unaffected by the standard adjuvant treatments such as radio‐ and chemotherapy. It is a particularly attractive strategy to improve the treatment outcomes and the quality of life in patients with the deadliest brain cancer, glioblastoma (GB). Testing of combination drug treatment protocols requires reliable, efficient, and biologically accurate preclinical testbeds applicable before the transition to clinical trials. The 3D in vitro models of GB are a promising platform for pharmacological research. However, there is notable methodological uncertainty and a highly scattered data landscape regarding drug testing in 3D in vitro models of GB. In particular, it is not completely clear how to mimic clinically relevant dozing and schedule of the main chemotherapy drug for GB, temozolomide (TMZ) in 3D in vitro GB models. Here, the authors carefully explore the available literature on the application of TMZ in 3D in vitro models of GB, both as a sole agent and in combination with other medications. The joint analysis of the tumor modeling approaches, the employed assays, and the obtained treatment responses provided in this review may be used as a roadmap for future research in combination treatments of GB.
Publisher: PeerJ
Date: 12-04-2021
DOI: 10.7717/PEERJ.11175
Abstract: Pregabalin and gabapentin improve neuropathic pain symptoms but there are emerging concerns regarding their misuse. This is more pronounced among patients with substance use disorder, particularly involving opioids. Co-ingestion of gabapentinoids with opioids is increasingly identified in opioid related deaths, however, the molecular mechanism behind this is still unclear. We have sought to determine whether pregabalin or gabapentin directly modulates acute μ receptor signaling, or μ receptor activation by morphine. The effects of pregabalin and gabapentin were assessed in HEK 293 cells stably transfected with the human μ receptor. Their effect on morphine induced hyperpolarization, cAMP production and ERK phosphorylation were studied using fluorescent-based membrane potential assay, bioluminescence based CAMYEL assay and ELISA assay, respectively. Pregabalin/gabapentin effects on morphine-induced hyperpolarization were also investigated in AtT20 cells. Pregabalin or gabapentin (1 µM, 100 µM each) did not activate the µ receptor or affect K channel activation or ERK phosphorylation produced by morphine. Neither drug affected the desensitization of K channel activation produced by prolonged (30 min) application of morphine. Gabapentin (1 µM, 100 µM) and pregabalin (1 µM) did not affect inhibition of forskolin-stimulated cAMP production by morphine. However, pregabalin (100 µM) potentiated forskolin mediated cAMP production, although morphine still inhibited cAMP levels with a similar potency to control. Pregabalin or gabapentin did not activate or modulate µ receptor signaling in three different assays. Our data do not support the hypothesis that gabapentin or pregabalin augment opioid effects through direct or allosteric modulation of the µ receptor. Pregabalin at a high concentration increases cAMP production independent of morphine. The mechanism of enhanced opioid-related harms from co-ingestion of pregabalin or gabapentin with opioids needs further investigation.
Location: Australia
No related grants have been discovered for Preeti Manandhar.