NOP Receptor Antagonists Decrease Alcohol Drinking in the Dark in C57BL/6J Mice.

Functional activation of heterotrimeric guanine nucleotide-binding proteins (G-proteins) via G-protein-coupled receptors (GPCRs) has been extensively explored using guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding assay. However, the conventional method is primarily applicable to Gi/o family without discrimination among G-protein subtypes. Therefore, this study aims to reestablish a novel method termed "[35S]GTPγS binding/immunoprecipitation assay" by identifying a most suitable anti-Gαi-3 antibody instead of the previously utilized, now withdrawn antibody. In the initial screening of commercially available anti-Gαi-3 antibodies, two were identified and one was selected for further investigations based on efficacy with adenosine-the most potent agonist in our previous research. After optimizing experimental conditions with rat and postmortem human brain membranes, the stimulatory effects of various agonists were evaluated. Some agonists, including nociceptin, exhibited sufficient stimulatory effects for further pharmacological characterization. Nociceptin increased [35S]GTPγS binding to Gαi-3 in a concentration-dependent manner, response that was insensitive to naloxone but potently inhibited using (±)-J-113397. The method described in this study provides a valuable strategy for determining the intrinsic efficacy of ligands at various GPCRs. This includes nociceptin/orphanin FQ opioid peptide (NOP) receptor selectively coupled to Gαi-3, providing insights into the pharmacological concept of "functional selectivity."

Limited access ethanol drinking in the dark in adolescent and adult mice

Binge alcohol drinking is a risk factor linked to numerous disease states including alcohol use disorder (AUD). While men binge drink more alcohol than women, this demographic gap is quickly shrinking, and preclinical studies demonstrate that females consistently consume more alcohol than males. Further, women are at increased risk for the co-expression of AUD with neuropsychiatric diseases such as anxiety and mood disorders. However, little is understood about chronic voluntary alcohol drinking and its long-term effects on behavior. Here, we sought to characterize sex differences in chronic binge drinking and the effects of protracted alcohol abstinence on anxiety- and affective-related behaviors in males and females. We assessed binge alcohol drinking patterns in male and female C57BL/6J mice using a modified Drinking in the Dark (DID) paradigm in which mice received home cage access to one bottle of 10% or 20% alcohol (EtOH) or water for 2h per day on Days 1-3 and to two bottles (EtOH/H2O + H2O) for 24h on Day 4 for 8 weekly cycles. Mice were then tested for the effects of protracted abstinence on avoidance, affective, and compulsive behaviors. Female mice consumed more alcohol than males consistently across cycles of DID and at 2, 4, and 24-h timepoints within the day, with a more robust sex difference for 20% than 10% EtOH. Females also consumed more water than males, an effect that emerged at the later time points; this water consumption bias diminished when alcohol was available. Further, while increased alcohol consumption was correlated with decreased water consumption in males, there was no relationship between these two measures in females. Alcohol preference was higher in 10% vs. 20% EtOH for both sexes. During protracted abstinence following chronic binge drinking, mice displayed decreased avoidance behavior (elevated plus maze, open field, novelty suppressed feeding) and increased compulsive behavior (marble burying) that was especially robust in females. There was no effect of alcohol history on stress coping and negative affective behaviors (sucrose preference, forced swim test, tail suspension) in either sex. Female mice engaged in higher volume binge drinking than their male counterparts. Although females also consumed more water than males, their higher alcohol consumption was not driven by increased total fluid intake. Further, the effects of protracted abstinence following chronic binge drinking was driven by behavioral disinhibition that was more pronounced in females. Given the reciprocal relationship between risk-taking and alcohol use in neuropsychiatric disease states, these results have implications for sex-dependent alcohol drinking patterns and their long-term negative neuropsychiatric/physiological health outcomes in humans.

Synergistic blockade of alcohol escalation drinking in mice by a combination of novel kappa opioid receptor agonist Mesyl Salvinorin B and naltrexone

High Drinking in the Dark (HDID) mice are sensitive to the effects of some clinically relevant drugs to reduce binge-like drinking

Reduction of alcohol intake by the positive allosteric modulator of the GABAB receptor, rac-BHFF, in alcohol-preferring rats

Supplementation with sodium butyrate protects against antibiotic-induced increases in ethanol consumption behavior in mice.

Modulation of Poly ADP Ribose Polymerase (PARP) Levels and Activity by Alcohol Binge-Like Drinking in Male Mice

Manipulations of nicotinic cholinergic receptors have been shown to influence both alcohol and nicotine intake. Sazetidine-A [6-(5(((S)-azetidine-2-yl)methoxy)pyridine-3-yl)hex-5-yn-1-ol] is a novel compound that potently and selectively desensitizes alpha4beta2 nicotinic receptors with only modest receptor activation. The goal of the present study was to examine the effects of sazetidine-A on alcohol and nicotine self-administration in alcohol-preferring (P) rats. P rats were given the choice of water or alcohol. Once stable baselines were established, the acute (0, 0.1, 0.3, 1, and 3 mg/kg, s.c.) and chronic (3 mg/kg for 10 days) effects of sazetidine-A on alcohol intake were assessed. Naltrexone (2.5 mg/kg) served as a positive control. The effect of sazetidine-A (3 mg/kg) and naltrexone (4 mg/kg) on saccharin (0.2%) preference was also assessed. In addition, the acute effects of sazetidine-A (3 mg/kg) and naltrexone (4 mg/kg) on alcohol intake after alcohol deprivation were evaluated. In another experiment, the effects of sazetidine-A (0, 1, or 3 mg/kg) on i.v. nicotine self-administration in P and NP rats were assessed. Sazetidine-A caused a dose-dependent reduction in alcohol intake. Chronic sazetidine-A also effectively reduced alcohol intake until the seventh day of treatment, when partial tolerance appeared to develop. In the post-deprivation study, sazetidine-A significantly reduced alcohol intake and preference. Sazetidine-A at 3 mg/kg significantly reduced nicotine self-administration in both lines. Sazetidine-A significantly reduced alcohol and nicotine intake in P rats that self-administer higher levels of both drugs. Sazetidine-A may hold promise for the treatment of alcohol and nicotine addiction.

Excessive alcohol consumption causes millions of deaths annually, yet current pharmacological treatments for alcohol use disorders show limited efficacy and poor adherence, creating an urgent need for new therapeutic alternatives. Aldehyde dehydrogenase 2 (ALDH2) metabolizes acetaldehyde, a key mediator of the rewarding effects of alcohol in the brain, making ALDH2 activation a promising therapeutic target. This study investigated whether flurbiprofen, an FDA-approved nonsteroidal anti-inflammatory drug that activates ALDH2, reduces alcohol intake compared to the experimental ALDH2 activator Alda-1 and the structurally similar NSAID ibuprofen. Male alcohol-preferring UChB rats received oral flurbiprofen (2.5-10 mg/kg), Alda-1 (5 mg/kg), or ibuprofen (5 mg/kg) during acquisition and chronic phases of voluntary alcohol consumption under a two-bottle free-choice paradigm. Both flurbiprofen and Alda-1 reduced alcohol intake by approximately 60% and similarly increased ALDH2 activity 3-4-fold in brain and liver tissues. Ibuprofen showed modest effects (25% alcohol intake reduction). In vitro assays confirmed that flurbiprofen and Alda-1, but not ibuprofen, activated ALDH2 in PC-12 cells. Enzymatic assays and molecular docking revealed that Alda-1 lacks cyclooxygenase-inhibitory activity, unlike flurbiprofen, suggesting that ALDH2 activation is the primary mechanism underlying reduced alcohol consumption. These findings identify flurbiprofen as a clinically available ALDH2 activator with significant translational potential for treating alcohol use disorders.

Alcohol use disorder (AUD) is characterized by alcohol use coupled with chronic relapse and involves brain regions including the bed nucleus of the stria terminalis (BNST). Here, we explore whether a subpopulation of BNST neurons, somatostatin (SST) expressing GABAergic neurons, play a role in an animal model of binge-like alcohol consumption, the Drinking in the Dark (DID) model. Chemogenetic activation of BNST SST neurons reduced binge alcohol consumption in female but not male SST-Cre mice, while inhibition of these neurons in the same mice had no effect. In addition, chemogenetic activation of these neurons did not cause apparent changes in models of anxiety-like behavior in either sex. Basal SST cell counts and intrinsic excitability of SST neurons were compared to attempt to understand sex differences in DREADD-induced changes in drinking, and while males had a greater number of BNST SST neurons, this effect went away when normalizing for total BNST volume. Together, these results suggest SST neurons in the BNST should be further explored as a potential neuronal subtype modulated by AUD, and for their therapeutic potential.

Alcohol operant self-administration: Investigating how alcohol-seeking behaviors predict drinking in mice using two operant approaches

Holiday Heart Syndrome (HHS) is a condition characterised by the development of atrial fibrillation (AF) and other tachyarrhythmias following episodes of binge drinking in individuals without pre-existing cardiac disease. As the binge drinking rate rises worldwide, it is increasingly important to understand the pathophysiology, epidemiology, and clinical significance of this syndrome. The objective of this literature review is to synthesise current evidence on the relationship between binge alcohol drinking and AF, exploring the underlying mechanisms and risk factors associated with HHS. A literature review was conducted using PubMed and Cochrane databases up to August 2024. Articles were selected based on predefined inclusion criteria, focusing on studies assessing the impact of acute alcohol intake on AF incidence. Studies evaluating chronic alcohol consumption, literature reviews, case series, and publications in languages other than English were excluded. A total of 11 studies met the inclusion criteria, comprising cohort and case-control studies. The findings consistently demonstrated a strong association between binge drinking and AF onset. Epidemiological evidence suggests that an increased incidence of new AF cases in individuals without structural heart disease can be attributed to alcohol consumption. Mechanistic insights identify several pathophysiological processes that contribute to the development of HHS, including autonomic dysregulation, ion channel modifications, and transient atrial structural changes. Acute alcohol consumption leads to increased sympathetic activity and reduced vagal tone, increasing heart rate variability and predisposing individuals to AF. Furthermore, alcohol has been shown to increase the activity of T-type calcium channels, which contributes to atrial ectopy and electrical instability. Structural alterations, such as reduced left atrial emptying fraction, have also been observed in binge drinkers, further supporting the link between alcohol and arrhythmogenesis. The evidence reviewed underscores the significant arrhythmogenic risk of binge drinking. While some studies suggest a J-shaped relationship between alcohol intake and AF risk, binge drinking consistently appears as a major trigger. However, variability in study populations and methodologies necessitates further research to establish safe consumption thresholds and interventions. Most studies relied on self-reported alcohol intake, with inconsistent screening methods, and physiological assessments included electrocardiogram monitoring and blood alcohol level measurements. This review highlights the significant role of binge drinking in the pathogenesis of HHS, stressing the need for targeted public health interventions and personalised patient counselling. Future research should prioritise longitudinal studies to improve risk assessment models and clarify the long-term cardiovascular impacts of alcohol-induced AF. Clinicians are encouraged to routinely screen for alcohol use, particularly in patients with a history of arrhythmias, to help prevent recurrent episodes and minimise associated complications.

The delta 2-opioid receptor antagonist naltriben selectively attenuates alcohol intake in rats bred for alcohol preference

The high rate of therapeutic failure in the management of alcohol use disorders (AUDs) underscores the urgent need for novel and effective strategies that can deter ethanol consumption. Recent findings from our group showed that ivermectin (IVM), a broad-spectrum anthelmintic with high tolerability and optimal safety profile in humans and animals, antagonized ethanol-mediated inhibition of P2X4 receptors (P2X4Rs) expressed in Xenopus oocytes. This finding prompted us to hypothesize that IVM may reduce alcohol consumption; thus, in the present study we investigated the effects of this agent on several models of alcohol self-administration in male and female C57BL/6 mice. Overall, IVM (1.25–10 mg/kg, intraperitoneal) significantly reduced 24-h alcohol consumption and intermittent limited access (4-h) binge drinking, and operant alcohol self-administration (1-h). The effects on alcohol intake were dose-dependent with the significant reduction in intake at 9 h after administration corresponding to peak IVM concentrations (Cmax) in the brain. IVM also produced a significant reduction in 24-h saccharin consumption, but did not alter operant sucrose self-administration. Taken together, the findings indicate that IVM reduces alcohol intake across several different models of self-administration and suggest that IVM may be useful in the treatment of AUDs.