Ethanol exposure during brain ontogeny: some long-term effects.

The timing, intensity, and duration of the period of maximal susceptibility of the developing brain to ethanol have not been clearly elucidated. This study was designed to determine whether a lower blood ethanol concentration (BEC) or a brief exposure during the brain growth spurt in the rat might cause permanent brain damage. Two doses of ethanol (4 g/kg body weight daily during days 6-16 after birth and 6 g/kg on day 6 only after birth) were used. Significant differences in whole brain weight, a disproportionately decreased cerebellar weight, altered balancing ability, and a decreased number of cerebellar cells were observed on days 17 and 70 postnatally in both ethanol-treated groups as compared with controls. Cerebellar weight a both ages were more markedly affected in animals treated only on day 6 postnatally than in animals treated throughout the major portion of the brain growth spurt. These results suggest that episodic exposure to ethanol during peak brain growth may be just as devastating to brain development as chronic exposure throughout the major portion of the brain growth spurt.