EFFECTS OF A NOVEL COMPOUND MCI-225 ON IMPAIRED LEARNING AND MEMORY IN RATS

Effects of MCI-225, orophenyl)6-methyl-2-(1-piperazinyl)thieno[2,3-d]p monohydrate hydrochloride] on experimental amnesia were studied in ra ts and compared with those of THA [9-amino-1,2,3,4-tetrahydroacridine] . In the Morris-type water maze task, MCI-225 (1-10 mg/kg, PO) reduced the spatial learning impairment induced by scopolamine (0.5 mg/kg, IF ). In a passive avoidance (PA) task, administration of MCI-225 prior t o training (1-30 mg/kg, PO) lessened the carbon dioxide (CO2)-induced amnesia in a dose-dependent manner. MCI-225 (1-100 mg/kg) did not affe ct gross behavior. THA (0.1-3 mg/kg, PO) reduced scopolamine-induced l earning deficits in the water maze task, but the effect was not signif icant. THA (0.3-3 mg/kg, PO) also ameliorated the CO2-induced amnesia, although slightly, in the PA task. THA (10 mg/kg, PO) increased locom otor activity and higher dose of THA (30 mg/kg, PO) induced tremor, hy persalivation, and muscle relaxation. These results suggest that MCI-2 25 lessens impairments in learning and memory without causing serious behavioral abnormalities.