Chronic alcohol consumption downregulates TRPA1 ion channel and the main peptidergic messengers of the Edinger-Westphal nucleus

The urocortin 1 (UCN1) and cocaine- and amphetamine-regulated transcript (CART) co-expressing neurons of the centrally projecting Edinger-Westphal nucleus (EWcp), regulate the function of reward- and addiction-related brain areas. EWcp/UCN1/CART neurons highly express the transient receptor potential ankyrin 1 (TRPA1) cation channel. We hypothesized that alcohol and its metabolites may influence TRPA1 ion channels. We also anticipated that 3-months chronic limited-access voluntary alcohol consumption in mice affects EWcp/TRPA1 expression resulting in altered UCN1 and CART dynamics and alcohol consumption. Alcohol preference and serum amylase were assessed to validate the model. In the mouse EWcp, immunofluorescence targeting UCN1 and CART peptides were performed to assess neuronal activation as well as UCN1 and CART peptides content. Mouse Trpa1, Cartpt, and Ucn1 as well as human TRPA1 expression was semi-quantified by RNAscope in situ hybridization. In silico modelling and computational docking were performed to test the ability of alcohol and its metabolites to activate human TRPA1 channels. Alcohol preference gradually declined over the course of the study. Alcohol treatment significantly increased serum amylase level and proportionally decreased Trpa1, Cartpt, and Ucn1 mRNA expression in the EWcp. Moreover, CART but not UCN1 peptide content was also reduced. We demonstrated TRPA1 expression in the human EWcp/UCN1/CART neurons and provided translational evidence that alcohol and its metabolites activate the human TRPA1. We conclude that reduced EWcp/TRPA1 expression may may diminish alcohol preference offering novel potential therapeutic target.