UNRAVELING THE MOLECULAR ENIGMA OF ETHANOL RELAPSE: EXPLORING PLASTICITY IN PARVALBUMIN-POSITIVE INTERNEURONS OF THE AMYGDALA.

Abstract

Ethanol is the most widely abused substance in Brazil and worldwide, being associated with numerous health issues, including mental disorders such as dependence. Treatments for ethanol dependence are highly restricted and have shown to be ineffective, with over 80% of patients experiencing relapse during treatment, even after prolonged periods of abstinence. Evidence suggests that the amygdala complex mediates behaviors related to ethanol relapse, with the GABAergic system playing a crucial role in these processes. The GABAergic system predominates in the amygdala and comprises projection neurons and interneurons. Among the GABAergic interneurons, parvalbumin-positive neurons, characterized by rapid firing, are considered orchestrators of amygdala-mediated responses. However, few studies have investigated the role of these interneurons in ethanol relapse. Therefore, the present project aims to investigate the role of plasticity in parvalbumin-positive interneurons of the amygdala in ethanol relapse. To achieve this goal, we will use C57/Bl6 mice exposed to cycles of alcohol intoxication and abstinence through an ethanol vapor chamber, which generates behavioral and physiological signs predictive of human dependence. Simultaneously, these animals will be subjected to the "Drink in the Dark" protocol to assess ethanol consumption and relapse. In the first experiment, immediately after the relapse test, the animals will undergo perfusion, and their brains will be processed for phenotypic analysis of the amygdala complex using double immunofluorescence staining. We will investigate the percentage of neuronal activation, both overall and specific to Glutamatergic, GABAergic, and parvalbumin-positive GABAergic neurons. In the second experiment, immediately after the relapse test, the amygdala will be dissected and processed for single-cell transcriptome analysis. Finally, the causal role of parvalbumin-positive interneurons will be assessed through inhibition or activation using optogenetic techniques. This study is expected to provide a better understanding of the underlying mechanisms of ethanol relapse, contributing to the development of more effective therapeutic approaches to treat ethanol dependence.