Long-term effect of postnatal alcohol exposure on the number of cells in the neocortex of the rat: a stereological study.

Behavioral and morphological studies suggest that exposure to alcohol during development may cause damage in the neocortex. In this study, rat pups were exposed to alcohol during the brain growth spurt and examined at adulthood to ascertain the long-term effect of alcohol exposure on the neocortex. Four-day-old rat pups were surgically implanted with an intragastric cannula while under ether anesthesia and artificially reared from postnatal day (PN) 4 through PN11. Two of the consecutive 12 daily feeds contained either alcohol (4.5 g/kg; alcohol-exposed) or an isocaloric maltose/dextrin solution (gastrostomy control) from PN4 through PN9. On PN115, animals were perfused intracardially and the brains removed. Unbiased stereological methods were used to determine the neocortical volume, the total number of neurons and glial cells in the entire neocortex and in layer V, and the mean cell volume of neurons or mean nuclear volume of glial cells in layer V. No effect of alcohol was seen in the neuronal population on either cell number or mean cell volume, nor was there any difference in the total number or mean nuclear volume of glial cells in layer V. These findings suggest that neither the entire neocortex nor layer V alone are vulnerable to permanent alcohol-induced cell death.