Ameliorating Effects of RU 47213, A Novel Oral and Long-lasting Cholinomimetic Agent, on Working Memory Impairments in Rats

The anti-amnesic effects of RU 47213 [1-(4-chlorophenoxycarbonyl)-1,2,5,6-tetrahydropyridine-3-carboxaldehyde- O-methyloxime], a prodrug with oral and long-lasting cholinergic activity, were evaluated on working memory impairments, using tasks of unequal levels of difficulty involving the same reinforcement and motivation in rats: a spatial-based task in a radial maze and a delayed reinforced alternation task in a T-maze. Tetrahydroaminoacridine (THA; tacrine), a cholinesterase inhibitor, was used as a reference. Groups of rats were trained in an automated radial maze or T-maze until they had attained an asymptotic level of performance. On test days, memory impairment was produced by administration of scopolamine (0.1 mg/kg SC) 15 min prior to testing. Both THA (1, 3, and 5 mg/kg) and RU 47213 (0.2, 0.5, 1, and 2 mg/kg) given prior to testing markedly reduced or suppressed the scopolamine-induced working memory deficits in both tasks. This activity was evidenced by either a significant decrease in the number of errors or an increase in the number of correct responses.These results show that RU 47213 possesses the capacity to reduce memory deficits induced by an impairment of cholinergic transmission in the rat