Transient induction of neuronal nitric oxide synthase in neurons of rat cerebral cortex after status epilepticus

The change in neuronal nitric oxide synthase (nNOS) expression after status epilepticus induced by kainate was examined in the rat cerebral cortex. Expressional change was assessed using nNOS immunohistochemistry and reverse transcription-polymerase chain reaction for nNOS mRNA. Constitutive nNOS-positive neurons was observed in the cerebral cortex of the control group. At 1 and 3 days after status epilepticus, nNOS-positive neurons were present in a deep layer of various cortical regions such as primary motor cortex, secondary motor cortex, primary somatosensory cortex, secondary somatosensory cortex, parietal association cortex, insular cortex, ectorhinal cortex, temporal association cortex, auditory cortex and visual cortex. The level of nNOS mRNA increased at 1, 3, 6 and 12 days after status epilepticus compared to controls. This report provides the first morphological evidence that nNOS are induced in neurons of the cerebral cortex following seizure. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.