Seizure -Related Change of NADPH -diaphorase and Calcium Binding Protein Positive Neurons in the Brain of Rats

Shin, Sun Young; Huh, Young Buhm; Kang, Kyoung Lan; Park, Chan; Kang, Min Jeong; Lee, Jae Ryong; Kim, Jung Hye; Yoo, Jin Hwa; Ahn, Hee Kyung

Abstract

Nitric oxide (NO) is a gaseous messenger that plays a role in neurotransmission, long term potentiation, depression and cerebral blood flow. Increases in intracellular calcium levels activate the enzyme NOS, and the NO released then diffuse to adjacent cells and activate guanylate cyclase. NO mediates the increase in cerebral blood flow during seizure activity. Therefore, the present study was aimed to investigate the change of NOS and calcium binding proteins in the rat cerebral cortex following seizure. Rats were injected with kainate (KA) and killed at 6 hours, 1, 3, 5 and 10 days after seizure. Expressional change of nNOS, calbindin D28k and parvalbumin was assessed by histochemistry, immunohistochemistry and microdensitometry in the rat brain. The intensity of the NADPH -d staining in rat cortical neurons showed a marked susceptibility to KA administration. At 6 hours and 3 days after seizure, the optical density of the NADPH -d staining was increased relative to the signal in saline treated control rats. At 5 and 10 days after seizure, the optical density of NADPH -d staining was not significantly different in most cortical regions compared to controls. In the hippocampus, the optical density of NADPH -d staining was highest at 5 days after seizure. The optical densities of calbindin D28k and parvalbumin positive neurons were various in the cerebral cortex, hippocampus and caudatoputamen during postseizure period. These results indicate that the calcium binding proteins investigated here are not essential for determining the activation of nNOS/NADPH -d positive neurons in the cerebral cortex and striatum.