HIPPOCAMPAL CHOLINERGIC ALTERATIONS AND RELATED BEHAVIORAL DEFICITS AFTER EARLY EXPOSURE TO ETHANOL

The present study was designed to ascertain septohippocampal cholinerg ic alterations and their related behavioral deficits after early expos ure to ethanol. Mouse pups were exposed to ethanol, 3 g/kg by daily su bcutaneous injection on postnatal days 2-14. At age 50 days, the ethan ol-exposed mice had significant reductions from control levels in eigh t-arm maze performance. For example, on the fourth testing day, the nu mber of correct entries in the ethanol group was 21 % below control le vels (P<0.05) and the number of trials needed to enter all arms was 48 % above control (P<0.001). It took the ethanol-exposed mice twice the time to reach criterion than it did control (P<0.01). A 33% increase f rom control level in muscarinic receptor number (B(max)) was found in the treated mice of age 22 days and a 64% increase at age 50 days (P<0 .001). However, no differences between control and treated groups coul d be detected in the presynaptic component of the cholinergic innervat ion, choline acetyltransferase activity. The results suggest that earl y ethanol exposure acts on hippocampal function similarly to phenobarb ital, probably via alterations in postsynaptic processes in the septoh ippocampal cholinergic pathways.