Comparative effects of physostigmine and neostigmine on acquisition and performance of a conditioned avoidance behavior in the rat

Abstract

The actions of physostigmine (0.10 and 0.15 mg/kg) and neostigmine (0.12 mg/kg) given s.c. on acquisition and performance of conditioned pole jumping were studied in rats receiving either 0.9% saline, (-) hyoscyamine or atropine methylnitrate. As estimated by inhibition of acetylcholinesterase (AChE) activity, physostigmine but not neostigmine entered the rat brain. Even though neostigmine did not significantly alter brain AChE activity in equimolar doses to physostigmine, it depressed both the acquisition and performance of a behavioral task, suggesting a predominant peripheral action. Although physostigmine depressed behavior mainly via a central action, its peripheral actions also play a role in its behavioral effects.