All issues > Volume 44(12); 2001

Original Article

J Korean Pediatr Soc. 2001;44(12):1432-1440. Published online December 15, 2001.

The Immunohistochemical Expression of Neuronal Nitric Oxide Synthase in Rat Hippocampus after Pentylenetetrazole-Induced Seizures

Doo-Kwun DK Kim¹, Tae-Jung TJ Jang²

¹Department of Pediatrics, College of Medicine, Dongguk University, Kyongju, Korea
²Department of Pathology, College of Medicine, Dongguk University, Kyongju, Korea

Correspondence Doo-Kwun DK Kim ,Email: pedepi@dumc.or.kr

Abstract

Purpose
: In order to determine the effect of neuronal nitric oxide synthase(nNOS) in seizure-related neuronal vulnerability of the hippocampus, the expression patterns of nNOS were examined in pentylenetetrazole(PTZ)-induced seizure groups and in PTZ seizure groups which were pretreated with nNOS inhibitors.
Methods
: Male Sprague-Dawley rats weighing 200-300 g were used in PTZ(40 mg/kg)-induced seizure experiments. A specific inhibitor, 50 mg/kg 7-nitroindazole(7-NI), and a non-specific inhibitor, 50 mg/kg nitro-L-arginine(L-NA) were treated 30 min before the administration of PTZ to block nNOS. nNOS expression was evaluated by using immunohistochemical staining in the hippocampus of each group.
Results
: The onset time of the first myoclonic jerk was markedly delayed in the 7-NI and the LNA pretreated groups in comparison to the PTZ group. In addition, 7-NI markedly suppressed the severity of PTZ-induced seizures. The expression of nNOS in the hippocampal CA3 area was higher than that in CA1 area in the PTZ treated groups. In the L-NA pretreated groups, the expression levels in the CA3 and CA1 areas were lower than those of the PTZ treated groups. Interestingly, in the 7-NI pretreated groups, the nNOS expression levels in CA1 and CA3 areas were makedly lower than those of PTZ and L-NA pretreated groups. There was no expression in CA2 area of all groups.
Conclusion
: These results suggest that the hippocampal neurons expressing nNOS may be vulnerable to PTZ-induced seizures and that nNOS may play an important role in seizure-related neuronal vulnerability.

Keywords :Neuronal nitric oxide synthase, NOS inhibitor, Immunohistochemistry, Pentylenetetrazole, trazole, Seizure, Rat