Dataset Information

COX-2 Inhibition Antagonizes Intra-Accumbens 2-Arachidonoylglycerol-Mediated Reduction in Ethanol Self-Administration in Rats.

ABSTRACT: BACKGROUND:Ethanol (EtOH) self-administration is particularly sensitive to the modulation of CB1 signaling in the nucleus accumbens (NAc) shell, and EtOH consumption increases extracellular levels of the endogenous cannabinoid CB1 receptor agonist 2-arachidonoyl glycerol (2-AG) in this brain region. Stimulation of CB1 receptor with agonists increases EtOH consumption, suggesting that EtOH-induced increases in 2-AG might sustain motivation for EtOH intake. METHODS:In order to further explore this hypothesis, we analyzed the alterations in operant EtOH self-administration induced by intra-NAc shell infusions of 2-AG itself, the CB1 inverse agonist SR141716A, the 2-AG clearance inhibitor URB602, anandamide, and the cyclooxygenase-2 (COX-2) inhibitor nimesulide. RESULTS:Surprisingly, self-administration of 10% EtOH was dose-dependently reduced by either intra-NAc shell SR141716A or 2-AG infusions. Similar effects were found by intra-NAc shell infusions of URB602, suggesting again a role for accumbal 2-AG on the modulation of EtOH intake. Intra-NAc shell anandamide did not alter EtOH self-administration, pointing to a specific role for 2-AG in the modulation of EtOH self-administration. Finally, the inhibitory effect of intra-NAc shell 2-AG on EtOH intake was significantly reversed by pretreatment with nimesulide, suggesting that oxidative metabolites of 2-AG might mediate these inhibitory effects on operant self-administration. CONCLUSIONS:We propose that 2-AG signaling in the NAc exerts an inhibitory influence on EtOH consumption through a non-CB1 receptor mechanism involving the COX-2 pathway.

SUBMITTER: Pavon FJ

PROVIDER: S-EPMC7680444 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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COX-2 Inhibition Antagonizes Intra-Accumbens 2-Arachidonoylglycerol-Mediated Reduction in Ethanol Self-Administration in Rats.

Pavon Francisco J FJ Polis Ilham I Stouffer David G DG Roberto Marisa M Martin-Fardon Rémi R Rodriguez de Fonseca Fernando F Parsons Loren H LH Serrano Antonia A

Alcoholism, clinical and experimental research 20201003 11

<h4>Background</h4>Ethanol (EtOH) self-administration is particularly sensitive to the modulation of CB<sub>1</sub> signaling in the nucleus accumbens (NAc) shell, and EtOH consumption increases extracellular levels of the endogenous cannabinoid CB<sub>1</sub> receptor agonist 2-arachidonoyl glycerol (2-AG) in this brain region. Stimulation of CB<sub>1</sub> receptor with agonists increases EtOH consumption, suggesting that EtOH-induced increases in 2-AG might sustain motivation for EtOH intake. ...[more]

PMID: 32944989

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Project description:BackgroundA clinical hallmark of alcohol use disorder is persistent drinking despite potential adverse consequences. The ventromedial prefrontal cortex (vmPFC) and dorsomedial prefrontal cortex (dmPFC) are positioned to exert top-down control over subcortical regions, such as the nucleus accumbens shell (NAcS) and basolateral amygdala, which encode positive and negative valence of ethanol (EtOH)-related stimuli. Prior rodent studies have implicated these regions in regulation of punished EtOH self-administration (EtOH-SA).MethodsWe conducted in vivo electrophysiological recordings in mouse vmPFC and dmPFC to obtain neuronal correlates of footshock-punished EtOH-SA. Ex vivo recordings were performed in NAcS D1 receptor-expressing medium spiny neurons receiving vmPFC input to examine punishment-related plasticity in this pathway. Optogenetic photosilencing was employed to assess the functional contribution of the vmPFC, dmPFC, vmPFC projections to NAcS, or vmPFC projections to basolateral amygdala, to punished EtOH-SA.ResultsPunishment reduced EtOH lever pressing and elicited aborted presses (lever approach followed by rapid retraction). Neurons in the vmPFC and dmPFC exhibited phasic firing to EtOH lever presses and aborts, but only in the vmPFC was there a population-level shift in coding from lever presses to aborts with punishment. Closed-loop vmPFC, but not dmPFC, photosilencing on a postpunishment probe test negated the reduction in EtOH lever presses but not in aborts. Punishment was associated with altered plasticity at vmPFC inputs to D1 receptor-expressing medium spiny neurons in the NAcS. Photosilencing vmPFC projections to the NAcS, but not to the basolateral amygdala, partially reversed suppression of EtOH lever presses on probe testing.ConclusionsThese findings demonstrate a key role for the vmPFC in regulating EtOH-SA after punishment, with implications for understanding the neural basis of compulsive drinking in alcohol use disorder.

Project description:Determining the neural factors contributing to compulsive behaviors such as alcohol-use disorders (AUDs) has become a significant focus of current preclinical research. Comparison of phenotypic differences across genetically distinct mouse strains provides one approach to identify molecular and genetic factors contributing to compulsive-like behaviors. Here we examine a rodent assay for punished ethanol self-administration in four widely used inbred strains known to differ on ethanol-related behaviors: C57BL/6J (B6), DBA/2J (D2), 129S1/SvImJ (S1), and BALB/cJ (BALB). Mice were trained in an operant task (FR1) to reliably lever-press for 10% ethanol using a sucrose-fading procedure. Once trained, mice received a punishment session in which lever pressing resulted in alternating ethanol reward and footshock, followed by tests to probe the effects of punishment on ethanol self-administration. Results indicated significant strain differences in training performance and punished attenuation of ethanol self-administration. S1 and BALB showed robust attenuation of ethanol self-administration after punishment, whereas behavior in B6 was attenuated only when the punishment and probe tests were conducted in the same contexts. By contrast, D2 were insensitive to punishment regardless of context, despite receiving more shocks during punishment and exhibiting normal footshock reactivity. Additionally, B6, but not D2, reduced operant self-administration when ethanol was devalued with a bitter tastant. B6 and D2 showed devaluation of sucrose self-administration, and punished suppression of sucrose seeking was context dependent in both the strains. While previous studies have demonstrated avoidance of ethanol in D2, particularly when ethanol is orally available from a bottle, current findings suggest this strain may exhibit heightened compulsive-like self-administration of ethanol, although there are credible alternative explanations for the phenotype of this strain. In sum, these findings offer a foundation for future studies examining the neural and genetic factors underlying AUDs.

Project description:Overeating is one of the most relevant clinical features in Binge Eating Disorder and in some obesity patients. According to several studies, alterations in the mesolimbic dopaminergic transmission produced by non-homeostatic feeding behavior may be associated with changes in the reward system similar to those produced by drugs of abuse. Although it is known that binge-eating is related with changes in dopaminergic transmission mediated by D2 receptors in the nucleus accumbens shell (NAcS), it has not been determined whether these receptors may be a potential target for the treatment of eating pathology with binge-eating. Accordingly, the aim of the present study was to evaluate whether sugar binging induced by intermittent access to a sucrose solution produced changes in the structure of feeding behavior and whether blocking D2 receptors prevented these changes. We used the intermittent access model to a 10% sucrose solution (2 h/day for 4 weeks) to induce sugar binging in Sprague Dawley female rats. Experimental subjects consumed in a 2-h period more than 50% of the caloric intake consumed by the subjects with ad-lib access to the sweetened solution without any increase in body weight or fat accumulation. Furthermore, we evaluated whether sugar binging was associated to the estrous cycle and we did not find differences in caloric intake (estrous vs. diestrus). Subsequently, we characterized the structure of feeding behavior (microstructural analysis) and the motivation for palatable food (breakpoints) of the subjects with sugar binging and found that feeding episodes had short latencies, high frequencies, as well as short durations and inter-episode intervals. The intermittent access model did not increase breakpoints, as occurred in subjects with ad-lib access to the sucrose. Finally, we evaluated the effects of D2 receptor blockade in the NAcS, and found that raclopride (18 nM) prevented the observed changes in the frequency and duration of episodes induced by intermittent access to the sucrose solution. Our results suggest that alterations in behavioral patterns associated with binge-eating behavior depend in part on the dopaminergic transmission in the NAcS and that the antagonism of D2 receptors may be a therapeutic tool for feeding pathology with binge-eating.

Dataset Information

COX-2 Inhibition Antagonizes Intra-Accumbens 2-Arachidonoylglycerol-Mediated Reduction in Ethanol Self-Administration in Rats.

Publications

COX-2 Inhibition Antagonizes Intra-Accumbens 2-Arachidonoylglycerol-Mediated Reduction in Ethanol Self-Administration in Rats.

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