To explore mechanisms of epileptogenesis in audiogenic seizures (AGS), we examined the expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazoleopropionic acid (AMPA) receptor subunits GluR1 and GluR2 and of the GluR-associated protein Narp in the hippocampus and the inferior colliculus (IC) from AGS-susceptible P77PMC rats after a single AGS and audiogenic kindling. Western blotting and immunohistochemistry showed that Narp was rapidly induced in both the hippocampus and the IC by AGS. In the hippocampus, up-regulation of Narp was concomitant with GluR1 and GluR2 under both conditions of a single AGS and AGS kindling. In the IC, however, Narp was up-regulated, GluR2 down-regulated, and GluR1 unchanged after kindling. In comparison with kindling, neither GluR1 nor GluR2 was changed, while Narp significantly increased in the IC following a single AGS. These findings suggest that down-regulation of AMPA receptor GluR2 subunit in the IC may contribute to AGS-mediated epileptogenesis, and up-regulation of Narp in the IC may be involved in audiogenic seizures.
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