Role of nitric oxide in electroshock and pentylenetetrazole seizure threshold in rats

There are contradictory reports on whether nitric oxide (NO) is a proconvul sant or anticonvulsant. Hence a study was designed to investigate the effec t of NO donor L-Arginine and NO synthesis inhibitor N omega-nitro-L-arginin e (NOARG) on electroshock- and pentylenetetrazole (PTZ)-induced seizure thr eshold in mts. L-arginine was tested in three doses (75, 150 and 300 mg/kg) , and NOARG was administered in doses of 4, 8 and 16 mg/kg. L-Arginine incr eased the intensity of current required to produce a threshold seizure, whe reas NOARG had the opposite effect. In PTZ-induced seizures, L-arginine sig nificantly decreased the dose of PTZ required to produce a threshold seizur e, while NOARG increased it. Hence, it was concluded that NO synthase inhib ition had the opposite effect in electroshock- and PTZ-induced seizures, me riting further studies on the mechanism of effect. (C) 1999 Prous Science. All rights reserved.