The Role of Endocannabinoids in Adulthood Alcohol Drinking After Adolescent Social Isolation

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PROJECT SUMMARY Chronic stress during the developmental period of adolescence increases the susceptibility to many neuropsychiatric diseases in adulthood, including alcohol drinking and anxiety-like behaviors. Social isolation is a particularly profound stressor with increasing human relevance, especially during the COVID-19 pandemic, when millions of adolescents have faced prolonged periods with limited and intermittent social interactions with peers. The endocannabinoid system (ECs) is critically involved in brain development and modulates synaptic transmission processes, including those in the central nucleus of the amygdala (CeA), a hub of stress and anxiety processing. A growing body of evidence indicates that adolescent social isolation stress and alcohol drinking hijacks the developing brain by disrupting the ECs and resulting in long-lasting synaptic neuroadaptations that predispose to alcohol use disorder (AUD), anxiety, aggressive behaviors, and social interaction deficits. Unlike adult alcohol exposure, the synaptic and behavioral effects of adolescent binge drinking often do not recover following periods of abstinence, suggesting that experiencing social isolation and alcohol drinking during adolescence has the potential to permanently disrupt the brain’s developmental trajectory. Here, I will utilize a modified model of intermittent social isolation stress to examine 1) the effect of intermittent social isolation on alcohol intake and preference during adolescence (PND28-56) in male and female Wistar rats and 2) identify the individual and synergistic consequences of adolescent social isolation and alcohol drinking on the EC- mediated mechanisms contributing to the anxiety-like behaviors and social interactions long-term effects. Additionally, I will assess the ECs neuroadaptations in the CeA and validate ECs as a potential drug target (AIM 1/K99). My hypothesis is that adolescent isolation stress and alcohol drinking induce lasting alterations on GABAergic and glutamatergic signaling in the CeA via maladaptive functions (downregulation) of the ECs (AIM 2/K99-R00). Finally, given that previous work as well as my preliminary data suggest that manipulating the ECs reduces alcohol drinking and anxiety-like behaviors, I will assess whether increasing endocannabinoids’ tone (i.e., 2-AG) during the abstinence period post-adolescence, by blocking ECs enzymatic degradation, is efficacious in reducing the anxious phenotype and in preventing drinking relapse in adulthood (AIM 3/R00). The K99 portion of this proposal involves extensive training using molecular and electrophysiological approaches to probe the functional protective role of the ECs system against later escalations in alcohol drinking and anxiety- like behaviors. Collectively, these experiments will provide critical insights into the impact of adolescent isolation stress and alcohol drinking on the resulting behavior and synaptic transmission in both sexes and will validate the ECs as druggable target for AUD and comorbid behaviors. The technical and conceptual training I will receive during this award will equip me with the multidisciplinary approach needed to continue this research line independently.