The insular but not the perirhinal cortex is involved in the expression offully-kindled amygdaloid seizures in rats

We have previously reported an important excitatory role of the perirhinal cortex (PRC) in rat kindling development using an immunohistochemistry tech nique. In this study, we investigated the roles of the PRC and the insular cortex (INS) located rostral to the PRC, in fully-kindled amygdaloid seizur es, using a microinjection technique in the rat kindling model of epilepsy. Following the establishment of daily kindling, we investigated the effects of microinjections of procaine hydrochloride, 2-amino-5-phosphonovalerate (APV; an N-methyl-D-aspartate (NMDA) receptor antagonist) and 2,3-dihydroxy -6-nitro-7-sulfamoyl-benzo(f)-quinoxaline (NBQX; an alpha -amino-3-hydroxy- 5-methyl-isoxazole-4-propionic acid (AMPA) receptor antagonist). Microinjec tions of these drugs into the ipsilateral PRC did not suppress kindled seiz ures. The possibility is that the process of kindling development forms nov el seizure-generalization pathways that do not require further activation o f the PRC. On the other hand, procaine and APV injected into the ipsilatera l INS significantly suppressed kindled seizures. The manner of suppression appeared to be 'all or none'. It is therefore possible that at least the ac tivation of NMDA receptors in the INS is necessary to express generalized k indled amygdaloid seizures. (C) 2001 Elsevier Science B.V. All rights reser ved.