Ethanol induced microcephaly in the neonatal rat: occurrence without withdrawal.

Neonatal rats exposed to ethanol with an artificial rearing technique on postnatal days 4--8 have been found to have up to 20% decrease in brain weight when examined on postnatal day 18. Following the four day ethanol exposure these animals went through a moderate to severe abstinence syndrome. Since the appearance of any detectable brain growth differences were not found until after the withdrawal period, it was possible that the microcephaly was a result of withdrawal and not ethanol exposure. To test this hypothesis, neonatal rats were exposed to ethanol for either the four day exposure period used in the previous work, or until determination of brain growth impairment at day 11. This last group of animals were administered a daily dose of ethanol such that they did not have an observable abstinence syndrome. Examination of brain weights on day 11 revealed no differences in the extent of the observed microcephaly between the ethanol exposure conditions, suggesting that withdrawal per se was not responsible for the production of the brain growth retardation.