Long-lasting enhancement of metabotropic excitatory amino acid receptor-mediated polyphosphoinositide hydrolysis in the amygdala/pyriform cortex of deep prepiriform cortical kindled rats.

Article date: 1992/1/8

PubMed ID: 1319260

Journal name: Brain research (ISSN: 0006-8993)


We have previously demonstrated that ibotenate (IBO)-stimulated polyphosphoinositide (PPI) hydrolysis is increased for a long period in the amygdala/pyriform cortex (AM/PC) of amygdala (AM)- and hippocampal (HIPP)-kindled rats. This finding indicates that enhanced function of the PPI-coupled excitatory amino acid (EAA) receptor may be associated with the long-lasting seizure susceptibility of kindling. The present study further examined PPI hydrolysis induced by trans-ACPD, a selective agonist of the metabotropic EAA receptor, as well as by IBO in brain slices of rats kindled from the deep prepiriform cortex (DPC). IBO-stimulated accumulation of [3H]inositol monophosphate ([3H]InsP) was significantly increased in the AM/PC by 162 (P less than 0.0001), 130 (P less than 0.005) and 81% (P less than 0.03) at 24 h, 7 days and 28 days, respectively, after the last kindled seizure, whereas it was increased significantly only at 24 h after the last seizure in the HIPP and did not change at any time in the limbic forebrain (LFB). The IBO-stimulated accumulation of [3H]InsP was significantly increased by 55% (P less than 0.01) in the AM/PC of partially kindled rats reaching an average stage of 3.7, but not in the AM/PC of those remaining at stage 1, 7 days after the last kindled seizure. Trans-ACPD-stimulated PPI hydrolysis was significantly increased in the AM/PC of DPC-kindled rats by 65 (P less than 0.05) and 45% (P less than 0.005) at 7 and 28 days, respectively, after the last kindled seizure. Cis-ACPD-stimulated PPI hydrolysis was also significantly increased in the AM/PC of DPC-kindled rats by 45 (P less than 0.03) and 30% (P less than 0.04) at 7 and 28 days, respectively, after the last seizure. There was no increase in trans-ACPD- or cis-ACPD-stimulated PPI hydrolysis in the HIPP or LFB. These results further confirm our previous studies showing that the metabotropic EAA receptor-stimulated PPI hydrolysis exhibited a long-lasting increase in the AM/PC irrespective of the primary stimulation site for kindling.

Author List: Akiyama K, Daigen A, Yamada N, Itoh T, Kohira I, Ujike H, Otsuki S

Publication Types: Journal Article; Research Support, Non-U.S. Gov't

Substances mentioned in the article: Neurotoxins; Phosphatidylinositol Phosphates; Phosphatidylinositols; Receptors, Neurotransmitter; Cycloleucine; 1-amino-1,3-dicarboxycyclopentane; Ibotenic Acid;

Mesh terms: Amygdala/drug effects; Animals; Cerebral Cortex/drug effects; Cycloleucine/analogs & derivatives; Electric Stimulation; Hydrolysis; Ibotenic Acid/pharmacology; Isomerism; Kindling, Neurologic; Limbic System/drug effects; Male; Neurotoxins/pharmacology; Phosphatidylinositol Phosphates; Phosphatidylinositols/metabolism; Prosencephalon/drug effects; Rats; Rats, Inbred Strains; Receptors, Neurotransmitter/drug effects; Seizures/metabolism;

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