Development of alcohol drinking behavior in rat lines selectively bred for divergent alcohol preference.

A characteristic of heritable alcoholism is an early onset of alcohol abuse, which may begin at or before the age of adolescence. The objective of the present study was to determine the ontogeny of alcohol drinking behavior before and during puberty in the selectively bred alcohol-preferring (P), alcohol-nonpreferring (NP), high alcohol drinking (HAD), and low alcohol drinking (LAD) lines of rats. In addition, the effects of postweaning housing conditions (single- or pair-housed) and initiation procedure (4 days forced ethanol or free-choice) were evaluated in male and female P rats. Results indicate that high alcohol drinking in P and HAD (replicate line 2) rats, as well as low alcohol drinking behavior in NP and LAD (replicate line 2) rats, is present as early as 3 to 4 weeks of age. Ethanol intakes in juvenile P and HAD rats reached levels of approximately 4 to 5 g/kg/day by 38 to 41 days of age and were comparable with levels observed in adults. Neither housing conditions nor ethanol initiation procedure significantly altered the acquisition or magnitude of alcohol intake levels in juvenile male and female P rats. These results suggest that the neural substrates underlying divergent ethanol drinking behavior in P/NP and HAD/LAD lines of rats are present early in life.