Impairment of one-trial passive avoidance learning in mice by scopolamine, scopolamine methylbromide, and physostigmine

Abstract

Scopolamine (1.0 mg/kg) or physostigmine (0.5 mg/kg) administered to different groups of mice in a passive avoidance test before learning resulted in impairment in a retrieval test 24 hr later. When these doses were combined, retrieval was markedly enhanced, indicating that antagonism could be revealed by a proper mixture of doses. No evidence of central effects was obtained from scopolamine methylbromide or neostigmine. These results support the hypothesis that central cholinergic neurons are involved in passive avoidance learning in mice.