Regional Vulnerability of the Developing Brain to Alcohol Exposure

These experiments were designed to look at regional vulnerability of the brain as a function of the daily dose and pattern of alcohol administration. Rat pups were given alcohol, using an artificial rearing technique, during postnatal days 4–10, a time period of brain growth which corresponds to that which occurs in humans during the third trimester. Alcohol was administered in 2 different paradigms: either continuously (with feedings every 3 hours) or condensed (with alcohol in 4 of 12 daily feedings). Regional weights, areal measurements or cell counts were recorded. With the condensed paradigm, a daily dose of 4.5 g/kg significantly lowered total brain weight and cerebellar weight, but a higher dose (6.6 g/kg) was needed to decrease brainstem weight significantly. Areal measurements revealed that continuous exposure to 9.8 g/kg/day reduced the hippocampus 26% and the cerebellum 15%, while the dentate gyrus was not affected. Following condensed exposure (6.6 g/kg/day), the cerebellum was reduced 23%, while the hippocampus and dentate gyrus were not significantly affected. Cell count data produced similar results. There was regional vulnerability with different brain regions and different neuronal populations within a single region unequally affected as a function of both daily alcohol dose and pattern of administration.