The effect of several putative cognition enhancers on a water maze acquisition deficit produced by pCPA + scopolamine combination treatment.

A combined treatment of a 3-day regimen of pCPA and low-dose scopolamine produced a significant deficit in the acquisition of a water maze task, which has been suggested as a model for the cognitive deficits of Alzheimer's disease. The putative cognition enhancers oxotremorine, captopril, ondansetron, and tacrine were used in attempts to alleviate the water maze impairment. The effects of oxotremorine were difficult to determine due to nonspecific motor effects causing alterations in swimming speed. No evidence for cognition-enhancing properties of captopril was found. Ondansetron showed a cognition-enhancing effect on one of 4 days, but only at a relatively high dose (1 mg/kg i.p.). Tacrine, however, alleviated the pCPA + scopolamine-induced cognitive deficit. This study may thus provide evidence for the usefulness of tacrine in treating spatial deficits in dementia.