Effects of the new cognition-enhancing agent nefiracetam in rats with cerebral embolism.

The effects of nefiracetam (DM-9384, CAS 77191-36-7) on the learning behavior and cholinergic and GABAergic neuronal transmitter systems of rats with experimentally-induced cerebral embolism were investigated. Cerebral embolisms were induced in male Wistar rats by injection of 800 microspheres 50 microns in diameter via the left internal carotid artery under 2% halothane anesthesia. Daily oral administration of nefiracetam (30 mg/kg/d) was started 9 days after embolization. Nefiracetam caused significant (p < 0.05) improvement of deficits in the learning of both water maze and passive avoidance tasks beginning 22 days after embolization of the rats. The drug also significantly restored decreases in cortical choline acetyltransferase (p < 0.05) and hippocampal glutamic acid decarboxylase activities (p < 0.01) in the embolized cerebral hemisphere and significantly increased cortical choline acetyltransferase (p < 0.05) and acetylcholinesterase activities (p < 0.05) in the contralateral cerebral hemisphere 21 days after embolization. These results demonstrate that nefiracetam improves cognitive dysfunction in the late phase in embolized rats and suggest that the effect is at least partly due to the increase in glutamic acid decarboxylase, choline acetyltranseferase and acetylcholinesterase activities.