Voluntary ethanol drinking during the first three postnatal weeks in linesof rats selectively bred for divergent ethanol preference

Background: Using a procedure first developed by Hall (1979), we examined e thanol self-administration in preweanling pups from Wistar rats and in line s of rats selectively bred for divergent ethanol preference (alcohol-prefer ring P, alcohol-nonpreferring NP, high-alcohol-drinking HAD-1 and -2, and l ow-alcohol-drinking LAD-2) to determine if factors contributing to high and low alcohol intakes are present early in development. Methods: From postnatal days 5 to 20, nondeprived male and female rat pups received 30 min daily access to either water or a 15% (v/v) ethanol solutio n. In each daily session, pups were placed in a heated chamber containing K imwipes soaked with a water or ethanol solution. Pups were weighed before a nd after each session, and intake levels were calculated as a percentage of body weight change. Results: Similar to previous reports, Wistar pups exhibited over a 2-fold h igher level of ethanol ingestion than water on postnatal days 9 through 14, with ethanol intakes approaching 3 g/kg body weight. When the drinking pat terns of the selected lines were examined, only the HAD replicate lines sho wed a comparable preference for ethanol versus water during the preweanling period. The ethanol consumption of P, NP, and LAD lines was not consistent ly distinguishable from water intake levels. To reveal whether early ethano l exposure would influence later ethanol drinking behavior, a subset of HAD and LAD rat pups received free-choice ethanol access upon weaning. Althoug h the divergent ethanol preference between high- and low-alcohol-drinking l ines was evident within the first 4 days of access (>4 g/kg/day for HAD; <2 g/kg/day for LAD), preweanling ethanol exposure did not alter the acquisit ion or maintenance of ethanol drinking in either line. Conclusions: Overall, these results suggest that (a) the enhanced ethanol i ngestion observed during the middle portion of the preweanling period is a robust phenomenon and generalizes across nonselected strains of rats, (b) s elective breeding for divergent alcohol preference has arrested this age-sp ecific effect in all but the HAD lines of rats, and (c) early ethanol expos ure does not alter genetic dispositions fur later high or low alcohol prefe rence.