Laboratory Research: Effects of Nefiracetam, a Novel Pyrrolidone-type Nootropic Agent, on the Amygdala-kindled Seizures in Rats

Purpose: Nefiracetam (NEF) is a novel pyrrolidonetype nootropic agent, and it has been reported to possess various pharmacologic effects as well as cognition-enhancing effects. The present study focused on the effects of NEF in amygdala-kindled seizures and its potential for antiepileptic therapy. Methods: Effects of NEF on fully amygdala-kindled seizures and development of amygdala-kindled seizures were investigated in rats and compared with those of levetiracetam (LEV), a pyrrolidone-type antiepileptic drug (AED). Results: In fully amygdala-kindled rats, NEF (25, 50, and 100 mg-kg, p.o.) decreased afterdischarge induction, afterdischarge duration, seizure stage, and motor seizure duration in a dose-dependent manner. LEV (25, 50, and 100 mg-kg, p.o.) had no effects on afterdischarge induction and slightly decreased afterdischarge duration, whereas it markedly decreased seizure stage and motor seizure duration. In contrast to the results in fully amygdala-kindled rats, NEF (25 and 50 mg-kg-day, p.o.) had few or no effects on the development of amygdala-kindled seizures. As well as fully amygdala-kindled seizures, LEV (50 mg-kg-day, p.o.) markedly inhibited the development of behavioral seizures without reducing daily afterdischarge duration. Conclusions: Although NEF possesses potent anticonvulsant effects on fully amygdala-kindled seizures, it has few or no effects on the development of amygdala-kindled seizures. LEV shows marked anticonvulsant effects on both phases of kindling. In fully amygdala-kindled rats, NEF inhibits both electroencephalographic and behavioral seizures, whereas LEV inhibits only behavioral seizures. This double dissociation suggests that NEF has a distinct anticonvulsant spectrum and mechanisms from those of LEV.