Immunohistochemical Evaluation of the Postnatal Effects of Acute Exposure to Ethanol on the Kinetics of Granule-cell Migration in Rat Cerebellum*

Exposure of the developing central nervous system (CNS) to ethanol leads to impaired cellular migration. In the cerebellar cortex, cell proliferation occurs in the early postnatal period. Granular cells generated in the external granular layer (EGL) migrate to their final destination at the internal granular layer. In this work, we examined the ethanol-induced alterations in cerebellar granular cells during their formation in 12-day postnatal (P12) Wistar rats (Rattus norvegicus). Three intraperitoneal (i.p.) injections of 20% ethanol (3 g/kg of body weight) were administered to each rat at 5 h intervals folowed by 5’-bromo-2deoxyuridine (BrdU, 60 mg/kg, i.p.) 16 h after the last injection. The rats were sacrificed 2 h or 24 h after the administration of BrdU and the brain was removed and embedded in paraffin. BrdU was subsequently detected immunohistochemically in sections of brain tissue. There was a decrease in the number of external granular cells and in the number of cell layers in the cerebellar EGL in all of the groups that received ethanol when compared to their respective controls. There was also a decrease in these parameters in the 2 h and 24 h survival period after BrdU administration. These results indicate that exposure to ethanol during granule cell generation and neuronal migration in the cerebellum is harmful, and that a study of the quantitative alterations in EGL neurons of the developing rat cerebellum exposed to ethanol in the postnatal period can provide a better understanding of ethanol-induced or related disturbances in the CNS.