Biology subjects

Bowrey, H. E.

Publications and source records attributed to Bowrey, H. E..

3 recordsLinked to original sources

bioRxiv2018

Orexin-1 receptor signaling in ventral pallidum mediates demand for the opioid remifentanil

Signaling at the orexin-1 receptor (Ox1R) is important for motivation for various drugs of abuse. Recently, our laboratory showed that systemic blockade of Ox1Rs decreased motivation for the potent and short-acting opioid remifentanil (Porter-Stransky et al, 2017). However, the central sites through which orexin acts to mediate motivation for opioids are not known. Here, we investigated ventral pallidum (VP) as a potential site of orexin action, as VP is a known mediator of opioid reward and is densely innervated by orexin-immunoreactive fibers. We used a within-session behavioral economics (BE) paradigm in which remifentanil price (responses/{micro}g iv remifentanil) was sequentially increased throughout the session. Rats were implanted with bilateral cannulae into VP, through which microinjections of SB334867 (SB), and orexin 1 receptor (Ox1R) antagonist, were given prior to BE testing. Rats were then extinguished and subjected to cue-induced reinstatement following intra-VP SB microinjection. We found that inhibition of Ox1R signaling in VP reduced both motivation (increased demand elasticity) for remifentanil and cued reinstatement of extinguished remifentanil-seeking without affecting baseline consumption or general locomotor activity. These effects were specific to the VP, as control injections of SB immediately dorsal to VP did not affect remifentanil-seeking. Together, these findings indicate a selective role of Ox1R signaling in VP in motivation and relapse for the opioid remifentanil.

animal behavior and cognition↗

bioRxiv2018

Demand elasticity predicts addiction endophenotypes and the therapeutic efficacy of an orexin/hypocretin-1 receptor antagonist in rats

Behavioral economics is a powerful, translational approach for measuring drug demand in both humans and animals. Here, we asked if demand for cocaine in rats with limited drug experience could be used to identify individuals most at risk of expressing an addiction phenotype following either long (LgA) or intermittent (IntA) access self-administration schedules, both of which model the transition to uncontrolled drug seeking. Moreover, because the orexin-1 receptor antagonist SB-334867 (SB) is particularly effective at reducing drug-seeking in highly motivated individuals, we asked whether demand measured after prolonged drug experience could predict SB efficacy. Demand elasticity () measured immediately following acquisition of cocaine self-administration ( baseline ) was positively correlated with assessed after 2w of LgA or IntA. Baseline also predicted the magnitude of compulsive responding for cocaine, drug seeking in initial abstinence, and cued reinstatement following LgA, IntA or standard short access (ShA). When demand was measured after LgA, IntA or ShA, predicted the same addiction endophenotypes predicted by baseline , as well as primed reinstatement and the emergence of negative emotional mood behavior following abstinence. Post-LgA/IntA/ShA also predicted the efficacy of SB, such that high demand rats showed greater reductions in motivation for cocaine following SB (10 and 30mg/kg) compared to low demand rats. Together, these findings indicate that might serve as a behavioral biomarker to predict individuals most likely to progress from controlled to uncontrolled drug use, and to identify individuals most likely to benefit from orexin-based therapies for the treatment of addiction.

neuroscience↗

bioRxiv2018

Increased number and activity of a lateral subpopulation of hypothalamic orexin/hypocretin neurons underlies the expression of an addicted state in rats

BackgroundThe orexin system is important for reward-driven motivation but has not been implicated in the expression of a multi-phenotype addicted state.\n\nMethodsRats were assessed for economic demand for cocaine prior to and following 14d of short- (ShA), long- (LgA) or intermittent-access (IntA) to cocaine. Rats were also assessed for a number of other DSM- V-relevant addiction criteria following differential access conditions. Orexin system function was assessed by i) quantification of numbers and activity of orexin cells, ii) pharmacological blockade of the orexin-1 receptor, and iii) subregion-specific knockdown of orexin cell populations.\n\nResultsIntA produced a cluster of addiction-like behaviors that closely recapitulate key diagnostic criteria for addiction to a greater extent than LgA or ShA. IntA was associated with plasticity in orexin cell function, including increased number and activity of orexin-expressing neurons within the lateral hypothalamic (LH) subregion. This plasticity persisted during protracted withdrawal from cocaine for at least 6 months and was associated with enhanced incubation of craving. Selective knockdown of LH orexin neurons reversed the addicted state, and orexin-1 receptor signaling played a larger role in drug seeking after IntA.\n\nConclusionsThese data provide the first evidence that LH orexin system function extends beyond general reward seeking to play a critical role in the expression of a multi-phenotype addicted-like state. Thus, the orexin/hypocretin system is a potential novel target for pharmacotherapies designed to treat cocaine addiction. In addition, these data point to the IntA model as a preferred approach to modeling addictionlike behavior in rats.

neuroscience↗