Immunohistochemical Analysis of Citrulline-Nitric Oxide Cycle Enzymes and Glutamine Synthetase in Different Regions of Brain in Epilepsy Rat Model

The aim of this study was to determine the immunoreactivity of neuronal and inducible nitric oxide synthetase, argininosuccinate synthetase, argininosuccinate lyase, glutamine synthetase in different regions of brain in rats of kainic acid mediated epilepsy. Male Sprague-Dawley rats were used in this study. The acute group animals were sacrificed after 2 hours and the chronic group animals were sacrificed after 5 days of a single subcutaneous injection of kainic acid (15 mg/kg body weight). The cerebral cortex, cerebellum and brain stem slices were fixed and immunohistostained for the above enzymes. Images were captured and analyzed. In acute group, argininosuccinate synthetase and inducible nitric oxide synthetase were increased in cerebral cortex and cerebellum, neuronal nitric oxide synthetase increased in cerebral cortex and brain stem, and there was no change in argininosuccinate lyase immunoreactivity compared to control group. In chronic group, glutamine synthetase was decreased and all other enzymes immunoreactivity was increased in all the brain regions tested. This study demonstrated the up-regulation of citrulline-nitric oxide cycle enzymes and may contribute to enhancing recycling of citrulline to arginine to support the increased production of nitric oxide in epilepsy. The decreased glutamine synthetase may increase glutamate in chronic epilepsy and may lead to neurodegeneration.