Altered gene expression of endogenous opioid system after alcohol exposure in adolescent rodents

 

The endogenous opioid system plays a key role in alcoholism. The different regulations of these genes are not only linked to the amount of alcohol consumed, but also to sex, as demonstrated in a rodent model. Therefore, the influence of sex in elucidating the mechanism of alcoholism should not be overlooked [1].

In alcohol use disorder, the endogenous opioid system genes seem to play a pivotal role [1]. For a better understanding of how alcohol consumption affects genes transcription, it is important to analyse when alcohol consumption occurs, especially in critical developmental periods such as adolescence. Mr Fabio Bellia (University of Teramo, Italy) and colleagues studied the potential effects of alcohol consumption in rats during adolescence on opioid system gene transcription in adulthood.

A short-term selection of rats was performed in an intermittent-access ethanol-intake protocol to generate 2 lines of high- and low-ethanol consumption in the animals. Twelve high ethanol-consumption animals and 12 low ethanol-consumption animals were randomly selected. Their brains were dissected 100 days after birth and 40 days after the last ethanol intake session. Total RNA was extracted and opioid messenger (m)RNA levels were assessed in the prefrontal cortex, nucleus accumbens, and ventral tegmental area with real-time quantitative polymerase chain reaction.

The 2 groups of rats exhibited differences in the expression of endogenous opioid system genes, observed in adulthood in different brain regions. Although there were no major differences in the quantity of alcohol consumed, the alterations in gene expression were more visible in males than in females. The levels of alcohol consumed significantly correlated with gene expression, which suggests that the altered expression of these genes in the brain is directly due to the amount of alcohol consumed during adolescence or is attributable to innate differences between the 2 lines.

 

1. Bellia F, et al. Long-term consequences of alcohol consumption: sex-dependent endogenous opioid system genes regulation. P.001. ECNP Congress 2020.

Posted on 2 November 20204 November 2020