Long-term consequences of alcohol consumption: sex-dependent endogenous opioid system genes regulation

FABIO M.C.; DADARIO C.; BELLIA, FABIO; PUCCI, MARIANGELA; FERNANDEZ M.; PAUTASSI R.M.

Niza

Workshop; ECNP Workshop for Early Career Scientists in Europe; 2020

European College of Neuropsychopharmacology

Introduction: Several studies have shown genetic component of alcohol consumption [1,2]. Unlike other pathologies,alcohol use disorder (AUD) seems to be caused by the interaction of different genes [3]. Among those, EndogenousOpioid System (EOS) genes seem to play a pivotal role inrelation to AUD, [4,5]. To better understand how alcoholconsumption affects genes transcription, it is important toanalyze when alcohol consumption occurs, and in particularin critical periods such as adolescence.Aims: We here studied the potential effects of alcohol consumption in rats during adolescence on opioid system genestranscription in adulthood. We selected for two generationsWistar rats, basing on their natural preference for high orlow alcohol intake across the entire adolescence.Materials and Methods: We performed a short-term selection (postnatal day [PD] 32-57) of rats in an intermittentaccess ethanol intake protocol to generate two lines of high(ADHI) and low (ADLO) ethanol consumption animals. Werandomly selected 12 ADLO and 12 ADHI (6 males and 6females), sacrificed at PD 100 (40 days after the last ethanolintake session) and, after brains dissection, total RNA wasextracted and opioid genes mRNA levels assessed in theprefrontal cortex (PFC), nucleus accumbens (NAc) andventral tegmental area (VTA), using Real-time quantitativepolymerase chain reaction (RT-qPCR).Statistical analysis: Two-way ANOVA was used to analyzeethanol intake (g/kg) differences between ADLO and ADHIgroups, comparing the average daily consumption for eachgroup. Gene expression data were analyzed using the nonparametric Mann-Whitney test and Bonferroni correctionwas used. Data are expressed as mean ± standard errorof the mean (SEM). All samples have been run in duplicatefor each assay. To evaluate the correlation between geneexpression (2-Ct values) and ethanol intake (g/kg/day),we performed Spearman correlation analysis. The P-values< 0.05 were considered statistically significant.Results: Absolute alcohol intake (g/kg) in ADHI and ADLOrats was monitored during 12 weekly sessions and alreadystarting from the second week, we observed a relevantdifference between the two lines. As regards gene expression, we observed in the PFC of males a down-regulationof pronociceptin (Pnoc P=0.031) and its receptor (Oprl1P=0.044) in ADHI respect ADLO. In the NAc instead, proopiomelanocortin (Pomc) is up-regulated in males ADHI(P=0.009) together Oprl1 (P=0.039) gene expression issignificantly reduced when compared to ADLO, whereasan increase of mu-opioid receptor (Oprm1 P=0.015) mRNAlevels is observed just in females ADHI. No differences wereobserved in the VTA.Discussion: We here reported a short-term selection duringadolescence of high-drinking rats and gene expressionanalysis showed that different levels of alcohol consumption are able to differentially alter selective EOS genestranscription. These differences seem to be sex-related,being more visible in males than in females, as confirmed bycorrelation analysis. Further studies are needed to betterunderstand how these differences between subjects can beexploited to possibly develop new therapies.No conflict of interestReferences[1] Tawa, E.A., Hall, S.D., Lohoff, F.W., 2016. Overview of the Genetics of Alcohol Use Disorder. Alcohol and Alcoholism 51 (5),507?514.[2] Pilatti, A., Caneto, F., Garimaldi, J.A., Vera, B., del, V., Pautassi, R.M., 2014. Contribution of Time of Drinking Onset andFamily History of Alcohol Problems in Alcohol and Dru