N-methyI-D-aspartate Receptor Subunit 1 Protein Expression in the Hippocampus and Temporal Cortex of Kainic Acid-Induced Epilepsy Rats

BACKGROUND: The N-methyl-D-aspartate receptor subunit 1 (NMDAR1) contributes to the incidence of epilepsy. However, the relationship between epilepsy-induced brain injury and NMDAR1 remains poorly understood.OBJECTIVE: To investigate changes in NMDAR1 protein expression in the hippocampus and temporal cortex of kainic acid-induced epilepsy rats.DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at the Department of Physiology and Department of Pathology, Basic Medical College of Jilin University from March 2002 to March 2003.MATERIALS: Rabbit anti-NMDAR1 antibody was purchased from Wuhan Boster Biological Technology, China.METHODS: A total of 80 healthy, male, Wistar rats, aged 22 weeks, were randomly assigned to sham-surgery (n = 10) and model (n = 70) groups. Epilepsy models were established by injecting kainic acid (1 mu L) into the right amygdala, and rats were sacrificed at 2, 6, 24, 72 hours, and 7, 15, 30 days after surgery, with 10 animals at each time point. The rats in the sham-surgery group were injected with 1 mu L phosphate buffered saline into the right amygdala.MAIN OUTCOME MEASURES: NMDAR1 protein expression in the hippocampus and temporal cortex at 2, 6, 24, 72 hours and 7, 15, 30 days after epilepsy was detected using immunohistochemistry and flow cytometry analysis.RESULTS: In the sham-surgery group, a few NMDAR1-positive cells were distributed in the hippocampus and temporal cortex. In the model group, NMDAR1-positive cells were increased in the hippocampus and temporal cortex at 2 hours following kainic acid-induced epilepsy. They were significantly increased at 6 hours, and slightly decreased at 7 days (CA3 region and temporal cortex), but remained greater than the sham-surgery group. This continued until day 30 (P < 0.01). In addition, there were more NMDAR1 positive cells in the hippocampal CA3 and dentate gyrus than the temporal cortex (P < 0.01).CONCLUSION: In epilepsy model rats, NMDAR1 protein expression was upregulated in the hippocampus and temporal cortex, and in particular in the hippocampal CA3 and dentate gyrus. NMDAR1 may participate in epilepsy and the excitation process of the epileptic brain.