Evidence for an involvement of the ammonia-decreasing action of L-argininein suppressing picrotoxin-induced convulsions in rats and its additive action with diazepam

The effects of pre- (30 min before challenge) and post-treatment (5 min aft er challenge) of L-arginine (840 mg kg(-1)) were tested on picrotoxin-induc ed increase in ammonia concentrations in brain regions (cerebral cortex, br ain stem and cerebellum) and the accompanying convulsive responses in adult male rats. The effect of pre- and post-treatment of L-arginine was tested on the action of diazepam against picrotoxin-induced convulsions. Picrotoxi n-induced increase in ammonia concentrations in the brain regions was rever ted partially by L-arginine pre-treatment. However, L-arginine pre-treatmen t failed to inhibit convulsions independently and concurrently with diazepa m. On the other hand, L-arginine posttreatment reverted ammonia to control level in all brain regions. A partial but significant inhibition of convuls ions was found in these animals. The effect produced concurrently by L-argi nine and diazepam post-treatment was much greater than that produced by the se agents independently, These results suggest that brain ammonia has a par tial but significant participation in the convulsant action of picrotoxin. L-arginine has produced a partial protection of picrotoxin-induced convulsi ons by reverting brain ammonia to control level. The data further suggest t hat the duration of action of L-arginine is considerably short and that L-a rginine has an additive anticonvulsant action with diazepam.