GABA and Glutamate Synaptic Coadaptations to Chronic Ethanol in the Striatum

Agmatine alleviates ethanol withdrawal-associated cognitive impairment and neurochemical imbalance in rats

The present study aimed to investigate the role of agmatine in the neurobiology underlying memory impairment during ethanol withdrawal in rats. Sprague-Dawley rats were subjected to a 21-day chronic ethanol exposure regimen (2.4 % w/v ethanol for 3 days, 4.8 % w/v for the next 4 days, and 7.2 % w/v for the following 14 days), followed by a withdrawal period. Memory impairment was assessed using the passive avoidance test (PAT) at 24, 48, and 72 h post-withdrawal. The ethanol-withdrawn rats displayed a significant decrease in step-through latency in the PAT, indicative of memory impairment at 72 h post-withdrawal. However, administration of agmatine (40 µg/rat) and its modulators (L-arginine, arcaine, and amino-guanidine) significantly increases the latency time in the ethanol-withdrawn rats, demonstrating the attenuation of memory impairment. Further, pretreatment with imidazoline receptor agonists enhances agmatine's effects, while antagonists block them, implicating imidazoline receptors in agmatine's actions. Neurochemical analysis in ethanol-withdrawn rats reveals dysregulated glutamate and GABA levels, which was attenuated by agmatine and its modulators. By examining the effects of agmatine administration and modulators of endogenous agmatine, the study aimed to shed light on the potential therapeutic implications of agmatinergic signaling in alcohol addiction and related cognitive deficits. Thus, the present findings suggest that agmatine administration and modulation of endogenous agmatine levels hold potential as therapeutic strategies for managing alcohol addiction and associated cognitive deficits. Understanding the neurobiology underlying these effects paves the way for the development of novel interventions targeting agmatinergic signaling in addiction treatment.

Chronic alcohol exposure alters action control via hyperactive premotor corticostriatal activity

Alcohol use disorder (AUD) alters decision-making control over actions, but disruptions to the responsible neural circuit mechanisms are unclear. Premotor corticostriatal circuits are implicated in balancing goal-directed and habitual control over actions and show disruption in disorders with compulsive, inflexible behaviors, including AUD. However, whether there is a causal link between disrupted premotor activity and altered action control is unknown. Here, we find that mice chronically exposed to alcohol (chronic intermittent ethanol [CIE]) showed impaired ability to use recent action information to guide subsequent actions. Prior CIE exposure resulted in aberrant increases in the calcium activity of premotor cortex (M2) neurons that project to the dorsal medial striatum (M2-DMS) during action control. Chemogenetic reduction of this CIE-induced hyperactivity in M2-DMS neurons rescued goal-directed action control. This suggests a direct, causal relationship between chronic alcohol disruption to premotor circuits and decision-making strategy and provides mechanistic support for targeting activity of human premotor regions as a potential treatment in AUD.

Inhibition of reinstatement of alcohol-induced conditioned place preference in mice by Lonicera japonica polysaccharide

Alcohol is one of the most commonly used addictive substances. Addiction memory is a necessary part of the mechanism underlying drug addiction. Lonicera japonica and its extract can mitigate organ damage caused by alcohol. In this study, Lonicera japonica polysaccharide (LJP) was extracted, and its effect on alcohol addiction memory was investigated. LJP inhibited the cue-induced reinstatement of conditioned place preference and elevated Tuj1 and DCX levels in the hippocampus to suppress neuronal damage. LJP also reduced the hippocampal glutamate (Glu) levels, alcohol-induced abnormal enhancement of the addiction memory, and decreased VPS34 phosphorylation and hyper activation of autophagy pathways in the hippocampus of alcohol-dependent mice. Our results suggest that LJP is a potential functional food to treat or ameliorate alcohol-induced addiction and that VPS34 is a potential target for modulating alcohol cravings.

Neurobiological mechanisms of control in alcohol use disorder - moving towards mechanism-based non-invasive brain stimulation treatments

Alcohol use disorder (AUD) is characterized by excessive habitual drinking and loss of control over alcohol intake despite negative consequences. Both of these aspects foster uncontrolled drinking and high relapse rates in AUD patients. Yet, common interventions mostly focus on the phenomenological level, and prioritize the reduction of craving and withdrawal symptoms. Our review provides a mechanistic understanding of AUD and suggests alternative therapeutic approaches targeting the mechanisms underlying dysfunctional alcohol-related behaviours. Specifically, we explain how repeated drinking fosters the development of rigid drinking habits and is associated with diminished cognitive control. These behavioural and cognitive effects are then functionally related to the neurobiochemical effects of alcohol abuse. We further explain how alterations in fronto-striatal network activity may constitute the neurobiological correlates of these alcohol-related dysfunctions. Finally, we discuss limitations in current pharmacological AUD therapies and suggest non-invasive brain stimulation (like TMS and tDCS interventions) as a potential addition/alternative for modulating the activation of both cortical and subcortical areas to help re-establish the functional balance between controlled and automatic behaviour.

Effect of chronic ethanol consumption in rhesus macaques on the nucleus accumbens core transcriptome

The nucleus accumbens core (NAcc) has been repeatedly demonstrated to be a key component of the circuitry associated with excessive ethanol consumption. Previous studies have illustrated that in a nonhuman primate (NHP) model of chronic ethanol consumption, there is significant epigenetic remodeling of the NAcc. In the current study, RNA-Seq was used to examine genome-wide gene expression in eight each of control, low/binge (LD*), and high/very high (HD*) rhesus macaque drinkers. Using an FDR < 0.05, zero genes were significantly differentially expressed (DE) between LD* and controls, six genes between HD* and LD*, and 734 genes between HD* and controls. Focusing on HD* versus control DE genes, the upregulated genes (N = 366) were enriched in genes with annotations associated with signal recognition particle (SRP)-dependent co-translational protein targeting to membrane (FDR < 3 × 10-59 ), structural constituent of ribosome (FDR < 3 × 10-47 ), and ribosomal subunit (FDR < 5 × 10-48 ). Downregulated genes (N = 363) were enriched in annotations associated with behavior (FDR < 2 × 10-4 ), membrane organization (FDR < 1 × 10-4 ), inorganic cation transmembrane transporter activity (FDR < 2 × 10-3 ), synapse part (FDR < 4 × 10-10 ), glutamatergic synapse (FDR < 1 × 10-6 ), and GABAergic synapse (FDR < 6 × 10-4 ). Ingenuity Pathway Analysis (IPA) revealed that EIF2 signaling and mTOR pathways were significantly upregulated in HD* animals (FDR < 3 × 10-33 and <2 × 10-16 , respectively). Overall, the data supported our working hypothesis; excessive consumption would be associated with transcriptional differences in GABA/glutamate-related genes.

Neurochemical Evidence of Preclinical and Clinical Reports on Target-Based Therapy in Alcohol Used Disorder

Alcohol use disorder (AUD) is a chronic relapsing disorder, which enforces a person to compulsively seek alcohol, restricting control over alcohol intake leads to emergence of an undesired emotional state during abstinence. There are recent advances for better understanding of neurocircuitry involved in the pathophysiology of AUD. Alcohol interaction with neuronal membrane proteins results in changes in neuronal circuits. It is also linked with the potential medication and their clinical validation concerning their pharmacological targets for alcoholic abstinence. This review covers research work from the past few decades on the therapeutic advances on treatment of alcohol dependence; further detailing the fundamental neurochemical mechanisms after alcohol administration. It also covers interaction of alcohol with GABAergic, glutaminergic, dopaminergic, serotonergic and opioid systems. This review further elaborated the neurobiology of noradrenergic, cholinergic and cannabinoid systems and their interaction with AUD. Elaborative information of potential drug targets under current exploration for AUD treatment with their mechanisms are reported here along with clinical outcomes and the associated side effects.