Nitric oxide production is decreased in the brain of the seizure susceptible EL mouse.

To investigate nitric oxide production in the brain of the EL mouse, an inbred mutant strain of the ddY mouse that is susceptible to convulsive seizures, we measured whole brain nitric oxide metabolites, and counted the number of nitric oxide-producing cells in the parietal cortex and striatum. Nitric oxide metabolites in the brain and serum were determined by measuring levels of nitrite plus nitrate. Nitric oxide-producing cells were demonstrated histochemically by staining for nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase. Levels of nitrite plus nitrate in the whole brain were significantly lower than those of the control mice, although levels of nitrite plus nitrate in the serum did not differ between groups. There were significantly fewer NADPH-diaphorase-positive cells in the parietal cortex and striatum of the EL mouse compared to the ddY controls. These results suggest that lower nitric oxide production in the brain may be related to the susceptibility of the EL mouse to convulsive seizures.