EFFECTS OF PRENATAL ETHANOL EXPOSURE ON PARVALBUMIN-EXPRESSING GABAERGIC NEURONS IN THE ADULT-RAT MEDIAL SEPTUM

Exposure of human fetuses to ethanol often results in the fetal alcoho l syndrome. Animal models of fetal alcohol syndrome have been develope d and used to examine the consequences of prenatal ethanol exposure on the central nervous system, The objective of this study was to determ ine the long-term effects of prenatal ethanol exposure on parvalbumin- expressing (PA+) GABAergic neurons of the rat medial septum. Pregnant Long-Evans rats were maintained on 1 of 3 diets from gestational day 0 to 21: an ethanol-containing liquid diet in which ethanol accounted f or 35% of the total calories, a similar diet with the isocaloric subst itution of sucrose for ethanol, or a lab chow control diet, Offspring were killed on postnatal day 60, and their brains were prepared for pa rvalbumin immunocytochemistry, Female rats exposed to the ethanol-cont aining diet during gestation had 42% fewer PA+ neurons in the medial s eptum and reduced PA+ cell density when compared with female rats expo sed to the sucrose diet, Ethanol females also had fewer PA+ neurons pe r unit volume than sucrose females, Male rats exposed to ethanol did n ot display a similar reduction in PA+ neurons or density, No effect of prenatal diet was found on the area or volume of the medial septum, n or were cell diameters affected. As such, prenatal exposure to ethanol seems to reduce permanently the number of PA+ neurons in the female r at medial septum without affecting area, volume, or neuronal size, Fun ctional implications and possible relations to the fetal alcohol syndr ome are discussed.