Glutamate Receptor Subunits Gene Expression in Kainate-induced Temporal Lobe Epilpsy Model

ABSTRACT

BACKGROUND: There is considerable controversy about the exact molecular mechanisms of excitatory amino acid receptors in epileptogenesis. METHODS: We used in situ hybridization to examine the hybridization density (HD) of n-methyl- D-aspartic acid receptor type 1 (NMDAR-1) and alpha-amino-3-hydroxy -5-methyl-4-isoxazole-propionate (AMPA) receptor type 2 (GluR-2) mRNA, in the hippocampus obtained from the kainic acid (KA)-induced status epilep-ticus (SE) model. Some Sprague-Dawley rats were injected with KA (10 mg/Kg; I.p.), and others with MK-801 (4 mg/kg) 20 minutes prior to KA. The rats were allowed to have 4-hour SE and were killed at 8 hours or 4 weeks after KA or MK-801/KA injection. HD of NMDAR-1 and GluR-2 mRNA in subfields of the hippocampus was measured by an image analysis system. RESULTS: A typical neuropathological finding of hippocampal sclerosis and spontaneous repetitive seizures (SRS) were observed in the KA injected rats, but not in the MK-801 pretreated rats, killed at 4 weeks. Compared with controls, the rats killed at 8 hours after KA showed increased CA1, CA2, and CA3 NMDAR-1 HD, and stratum granulosum (SG) GluR-2 HD. The increase of NMDAR-1, not GluR-2, HD was blocked effectively by MK-801. The increase of SG GluR-2 HD remained until 4 weeks after the KA injection. CONCLUSIONS: Not only the NMDAR-1activa-tionbut also the GluR-2 activation is an important factor in delaying hippocampal neuronal loss and epileptogenesis. (J Korean Neurol Assoc 19(1):36~44, 2001