Ethanol-induced microcephaly in neonatal rats: relation to dose.
Neonatal rats were exposed to several different doses of ethanol during the first part of the brain growth spurt (postnatal days 5, 6, 7 and 8) and examined for decreased brain weights at 18 days of age. The occurrence of reduced brain weight was found to require a dose of at least 6.0 g ethanol/kg body weight/day. Above this dose, the extent of brain weight reduction was related to increased dose, provided death from overdose did not occur. Measured blood ethanol levels suggested that blood levels below 100 mg/100 ml failed to result in significant brain weight reductions. The possibility that blood ethanol levels below this point may impair brain growth in more subtle ways remains to be determined.