CHRONIC (-) DEPRENYL ADMINISTRATION INCREASES DENDRITIC ARBORIZATION IN CA3 NEURONS OF HIPPOCAMPUS AND ACHE ACTIVITY IN SPECIFIC REGIONS OFTHE PRIMATE BRAIN

The mechanism by which (-) deprenyl enhances cognitive function in Alz heimer's disease (AD) is not yet understood. (-) Deprenyl (0.2 mg/kg/d ay) was administered intramuscularly to adult male monkeys (n = 6) for 25 days. Control monkeys (n = 6) received physiological saline by the same route. The activity of acetylcholinesterase (AChE) in different brain regions and the dendritic arborization in CA3 pyramidal neurons of hippocampus were analysed, (-) Deprenyl-treated monkeys showed a si gnificant increase in the AChE activity by 43% (p < 0.001) in the fron tal cortex, by 39% (p < 0.025) in the motor cortex, by 66% (p < 0.001) in the hippocampus and by 26% (p < 0.05) in the striatum compared to controls. The branching points and the intersections of both apical an d basal dendrites of CA3 hippocampal pyramidal neurons were also signi ficantly increased in (-) deprenyl-treated monkeys. Enhanced AChE acti vity may increase dendritic arborization in the hippocampus and it may also play a role in improving cognitive functions observed in AD, fol lowing(-) deprenyl treatment. (C) 1998 Elsevier Science B.V. All right s reserved.