Aim: To further explore the roles of endogenous nitric oxide (NO) or NO derivatives in complex partial seizures and generalized convulsions.
Methods: The effect of pretreatment with L-nitroarginine (L-NNA), an inhibitor of nitric oxide synthase (NOS), or L arginine (L-Arg), a precursor of NO on kainic acid (KA)-induced seizure in rats and the changes in the concentration of NO2 -/NO- in the hippocampus were determined.
Results: The rats appeared with wet dog shakes (WDS) at 15 min and then occurred generalized convulsions during 1 h to 3 h after administration of KA (10 mg/kg i.p.). However, the pretreatment of L-NNA (50 mg/kg) so dramatically promoted and enhanced KA-induced behavioral seizures that the latency of generalized convulsion was shorten dramatically, and the mortality was greatly high. In contrast, the pretreatment with L-Arg (40 mg/kg) markedly delayed or weakened KA-induced behavioral changes, such as increasing latency of WDS and generalized convulsion, shortening time o f seizure and none of animal died during observed time. The concentration of NO2- /NO3- in the hippocampus increased immediately at 30 min and remained to 7 d after the administration of KA. Compared with control group (pretreatment with NS), the concentration of NO2- / NO3- in the hippocampus apparently increased at 3 h and 3 d after the administration of KA in the rats with L-Arg pretreatment.
Conclusion: The endogenous NO (NO or NO derivatives) mediators may play an important role against excitotoxin induced seizures in rats.