Effects of L-arginine on picrotoxin-induced increase in brain ammonia concentrations and convulsions in rats.

The effect of L-arginine (840 mg/kg) pre- (30 min before challenge) and post-treatment (5 min after challenge) period was tested on picrotoxin-induced increase in ammonia concentrations in brain regions (cerebral cortex, brain stem and cerebellum) and the accompanying convulsive responses in adult male rats. The combined effect of L-arginine and diazepam was also tested against picrotoxin-induced convulsions. Picrotoxin-induced increase in ammonia was reverted partially by L-arginine pretreatment. However, L-arginine pretreatment did not show anticonvulsant effect independently or concurrently with diazepam. On the other hand, L-arginine post-treatment reverted ammonia to control level in all brain regions. A partial but significant inhibition of convulsion responses was found in these animals. The combined effect of diazepam and L-arginine post-treatment was much greater than that produced by these agents independently. These findings suggest that ammonia has a partial but significant participation in the convulsant action of picrotoxin. L-arginine has a potential to revert brain ammonia to control level in picrotoxin-treated animals and thereby it has produced a partial protection. The data further indicate that the duration of action of L-arginine is considerably short and has an additive anticonvulsant action with diazepam.