Minaprine improves impairment of working memory induced by scopolamine and cerebral ischemia in rats

Abstract

Using a repeated acquisition procedure in a three-panel runway apparatus, the effects of minaprine on the impairment of working memory produced by scopolamine, ethylcholine aziridinium ion (AF64A) or cerebral ischemia were investigated in rats. Minaprine (3.2-32 mg/kg IP) as well as idebenone (10-100 mg/kg IP) and physostigmine (0.1-0.32 mg/kg IP) dose-dependently reduced the increase of errors (pushes made on the two incorrect panels located at each choice point) induced by 0.56 mg/kg IP scopolamine. Cerebral ischemia for 5 min caused a significant increase of errors in the runway task. Minaprine at 3.2 and 10 mg/kg administered IP immediately after blood recirculation and again 30 min before the runway test conducted 24 h after ischemia, significantly reduced increases in errors expected to occur after 5 min of ischemia. Physostigmine 0.1 mg/kg similarly attenuated the increase in errors in ischemic rats. However, minaprine at doses up to 32 mg/kg IP failed to reduce the increase of errors induced by AF64A 2.5 nmol injected into the dorsal hippocampus. These findings suggest that minaprine exerts an ameliorating effect on amnesia produced by scopolamine and cerebral ischemia, probably through mediation of its stimulant action on central cholinergic systems.