P.001 Long-term consequences of alcohol consumption: sex-dependent endogenous opioid system genes regulation

BELLIA, F.; FERNÀNDEZ, M.S.; FABIO, M.C.; PUCCI, M.; PAUTASSI, R.M.; D'ADDARIO, C.

EUROPEAN NEUROPSYCHOFARMACOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020 vol. 40

0924-977X

Introduction: Several studies have shown genetic compo- nent of alcohol consumption [1 , 2] . Unlike other pathologies, alcohol use disorder (AUD) seems to be caused by the in- teraction of different genes [3] . Among those, Endogenous Opioid System (EOS) genes seem to play a pivotal role in relation to AUD, [4 , 5] . To better understand how alcohol consumption affects genes transcription, it is important to analyze when alcohol consumption occurs, and in particular in critical periods such as adolescence. Aims: We here studied the potential effects of alcohol con- sumption in rats during adolescence on opioid system genes transcription in adulthood. We selected for two generations Wistar rats, basing on their natural preference for high or low alcohol intake across the entire adolescence. Materials and Methods: We performed a short-term selec- tion (postnatal day [PD] 32-57) of rats in an intermittent- access ethanol intake protocol to generate two lines of high (ADHI) and low (ADLO) ethanol consumption animals. We randomly  selected  12  ADLO  and  12  ADHI  (6  males  and  6 females), sacrificed at PD 100 (40 days after the last ethanol intake session) and, after brains dissection, total RNA was extracted  and  opioid  genes  mRNA  levels  assessed  in  the prefrontal  cortex  (PFC),  nucleus  accumbens  (NAc)  and ventral tegmental area (VTA), using Real-time quantitative polymerase chain reaction (RT-qPCR).Statistical analysis: Two-way ANOVA was used to analyze ethanol intake (g/kg) differences between ADLO and ADHI groups, comparing the average daily consumption for each group. Gene expression data were analyzed using the non- parametric  Mann-Whitney  test  and  Bonferroni  correction was  used.  Data  are  expressed  as  mean  ± standard  error of the mean (SEM). All samples have been run in duplicate for each assay. To evaluate the correlation between gene expression (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 ADLO rats was monitored during 12 weekly sessions and already starting  from  the  second  week,  we  observed  a  relevant difference between the two lines. As regards gene expres- sion, we observed in the PFC of males a down-regulation of  pronociceptin  (Pnoc  P  =  0.031)  and  its  receptor  (Oprl1 P  =  0.044) in ADHI respect ADLO. In the NAc instead, pro- opiomelanocortin  (Pomc)  is  up-regulated  in  males  ADHI (P  =  0.009)  together  Oprl1  (P  =  0.039)  gene  expression  is significantly  reduced  when  compared  to  ADLO,  whereas an increase of mu-opioid receptor (Oprm1 P  =  0.015) mRNA levels is observed just in females ADHI. No differences were observed in the VTA. Discussion: We here reported a short-term selection during adolescence  of  high-drinking  rats  and  gene  expression analysis showed that different levels of alcohol consump- tion  are  able  to  differentially  alter  selective  EOS  genes transcription.  These  differences  seem  to  be  sex-related, being more visible in males than in females, as confirmed by correlation analysis. Further studies are needed to better understand how these differences between ssubjects can be exploited to possibly develop new therapies.