Scopolamine disrupts leverpress shock escape learning in rats.

Five groups of rats were tested on a discrete-trial leverpress shock escape task 30 min following an intraperitoneal injection of either 0 (saline), 0.2, 1.0, or 5.0 mg/kg scopolamine hydrobromide, or 5.0 mg/kg methylscopolamine hydrobromide. The results indicated that scopolamine, but not methylscopolamine, disrupted escape performance and this disruption was dose-related. These findings are consistent with both disinhibition and reduced freezing explanations of anticholinergic effects and support the view that reduced acetylcholine is involved in the behavioral effects of septal lesions.