Abstract: Abstract: Objective To investigate the effect of zonisamide as a new antiepileptic drug on nitric oxide (NO) content and nitric oxide synthase (NOS) activity in serum and brain tissue of epileptic rats. Methods Eight healthy rats were used as normal control group, and twenty- four epileptic rats induced by pentrazol were randomly divided into epilepsy model group, zonisamide group and phenobarbital group. Levels of NO and malondialdehyde (MDA) content, NOS and superoxide dismutase (SOD) activity in serum and brain tissue were detected in four groups. Results Forty-two rats were injected pen⁃ trazol, and 35 (83%) rats were established the rat model successfully. Epileptic waves were visible in EEG of epileptic rats. The concentrations of NO, MDA and the activity of NOS in serum and brain were significantly increased, the activity of SOD was significantly decreased, in epileptic rats than those of control rats. The concentrations of NO and MDA were significantly increased; the activity of SOD was significantly decreased, in brain in phenobarbital group compared with those of control group. There were significantly lower levels of NO, MDA and NOS, and significantly higher level of SOD in serum and brain tissue in zonisamide group and phenobarbital group than those of epileptic model group (P＜0.05). Conclusion Zonisamide plays an antiepileptic role by reducing the concentration of NO in brain of epileptic rats.

Key words: anticonvulsants, epilepsy, pentylenetetrazole, nitric oxide, nitric oxide synthase, malondialdehyde, superoxide dismutase, rats, Sprague-Dawley, zonisamide