ORCID Profile
0000-0002-3634-6463
Current Organisations
University of Calgary
,
Victoria University of Wellington School of Biological Science
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Publisher: Cold Spring Harbor Laboratory
Date: 04-02-2023
DOI: 10.1101/2023.02.03.527084
Abstract: Impaired motivational drive is a key feature of depression. Chronic stress is a known antecedent to the development of depression in humans and depressive-like states in animals. Whilst there is a clear relationship between stress and motivational drive, the mechanisms underpinning this association remain unclear. One hypothesis is that the endocrine system, via corticotropin-releasing hormone (CRH) in the paraventricular nucleus of the hypothalamus (PVN PVN CRH ), initiates a hormonal cascade resulting in glucocorticoid release, and that excessive glucocorticoids change brain circuit function to produce depression-related symptoms. Another, mostly unexplored hypothesis is that the direct activity of PVN CRH neurons and their input to other stress- and reward-related brain regions drives these behaviours. To further understand the direct involvement of PVN CRH neurons in motivation, we used optogenetic stimulation to activate these neurons one hour/day for 5 consecutive days and showed increased acute stress-related behaviours and long-lasting deficits in the motivational drive for sucrose. This was associated with increased Fos-protein expression in the lateral hypothalamus (LH). Direct stimulation of the PVN CRH inputs in the LH produced a similar pattern of effects on sucrose motivation. Together, these data suggest that PVN CRH neuronal activity may be directly responsible for changes in motivational drive and that these behavioural changes may, in part, be driven by PVN CRH synaptic projections to the LH.
Publisher: Cold Spring Harbor Laboratory
Date: 03-05-2020
DOI: 10.1101/2020.05.01.073205
Abstract: Overconsumption of highly palatable, energy dense food is considered a key driver of the obesity pandemic. The orbitofrontal cortex (OFC) is critical for reward valuation of gustatory signals, yet how the OFC adapts to obesogenic diets is poorly understood. Here we show that extended access to a cafeteria diet impairs astrocyte glutamate clearance, which leads to a heterosynaptic depression of GABA transmission onto pyramidal neurons of the OFC. This decrease in GABA tone is due to an increase in extrasynaptic glutamate, which acts via metabotropic glutamate receptors to liberate endocannabinoids. This impaired the induction of endocannabinoid-mediated long-term plasticity. In obese rats, this cascade of synaptic impairments was rescued by restoring astrocyte glutamate transport with the nutritional supplement, N-acetylcysteine. Together, our findings indicate that obesity targets astrocytes to disrupt the delicate balance between excitatory and inhibitory transmission in the OFC. Diet-induced obesity induces hypertrophy of astrocytes and impairs their ability to transport glutamate. Failure of astrocytes to clear extrasynaptic glutamate drives endocannabinoid-mediated inhibitory long-term depression of principal output neurons in the OFC. Astrocytic glutamate transporter function is restored with NAC, which rescues the synaptic deficits.
Publisher: Wiley
Date: 31-07-2012
Publisher: Wiley
Date: 21-06-2023
Abstract: Coral reef habitat quality is declining in many locations because of heatwaves (coral bleaching) and other disturbances. Reef‐building corals provide refuge from predation, so declining complexity restricts the transfer of energy to upper trophic levels. We use a size‐based ecosystem model to test systematically the effects of refuge at specific sizes and the impacts of distributions of refuges that vary in size. Outcomes are assessed in terms of ecosystem service provision. Simulations indicate that refuge sheltering fish between 5 and 10 cm in length enhances fish biomass and fisheries productivity, for ex le, increasing herbivore biomass by up to 80%. We identify and present a range of refuge profiles that can theoretically improve ecosystem service provision by as much as sixfold. Profiles where refuge availability decreases with increasing fish size consistently outrank other designs. Synthesis and application : These results highlight how critical small‐scale refuge is for coral reefs, and how we might design artificial reefs to maximise service provision.
Publisher: Springer Science and Business Media LLC
Date: 17-03-2017
DOI: 10.1007/S00213-017-4575-Z
Abstract: Relaxin-3/RXFP3 signalling is proposed to be involved in the neuromodulatory control of arousal- and stress-related neural circuits. Furthermore, previous studies in rats have led to the proposal that relaxin-3/RXFP3 signalling is associated with activation of the hypothalamic-pituitary-adrenal axis, but direct evidence for RXFP3-related actions on the activity of hypothalamic corticotropin-releasing hormone (CRH) neurons is lacking. In this study, we investigated characteristics of the relaxin-3/RXFP3 system in mouse hypothalamus. Administration of an RXFP3 agonist (RXFP3-A2) intra-cerebroventricularly or directly into the paraventricular nucleus of hypothalamus (PVN) of C57BL/6J mice did not alter corticosterone levels. Similarly, there were no differences between serum corticosterone levels in Rxfp3 knockout (C57BL/6J
Publisher: Wiley
Date: 05-05-2021
DOI: 10.1111/DDI.13268
Abstract: Functional ersity metrics inform how species’ traits relate to ecosystem functions, useful for quantifying how exploitation and disturbance impact ecosystems. We compare the functional ersity of entire fish communities in a shallow‐water region with a deep‐sea region for further insight into the differences between these ecosystem types. The regions compared in this study were selected to represent a shallow‐water coastal region, Tasman and Golden Bays (TBGB), and a deep‐sea region, Chatham Rise (CR), in New Zealand. Functional ersity was assessed using four metrics: functional richness, evenness, ergence and dispersion. We compared these metrics across four key functions: habitat use, feeding, locomotion and life history. Our results showed that overall, the shallow‐water and deep‐sea ecosystems had equal ersity. When focusing on the four ecological functions, the two ecosystems exhibited equal ersity metrics across most analyses. Of the significantly different results, the deep‐sea had higher functional richness for habitat use and locomotion traits, lower functional dispersion for feeding and lower functional evenness for life history. Differences across the functions highlight higher ersity of habitat utilization by deep‐sea fish, while lower ersity in feeding suggests deep‐sea fish tend towards generalist diets, likely driven by low food availability. Deep‐sea fish displayed an increased range of locomotive traits in our analyses, but this conflicts with existing evidence and warrants further study. Life‐history results suggest deep‐sea fish exhibit higher clustering of traits, indicating potential under‐utilization of life‐history strategies in the deep‐sea. Our results demonstrate that although deep‐sea fish communities have similar levels of ersity to shallow‐water communities, the traits that structure this ersity differ, and therefore, the systems may respond to exploitation differently.
Location: New Zealand
No related grants have been discovered for Jaideep Bains.