Hippocampal kindling enhances excitatory amino acid receptor-mediated polyphosphoinositide hydrolysis in the hippocampus and amygdala/pyriform cortex.
We recently demonstrated that a long-lasting increase in ibotenate-stimulated polyphosphoinositide (PPI) hydrolysis in the amygdala/pyriform cortex (AM/PC) is associated with seizure susceptibility of amygdala (AM)-kindled rats. The present study examined (1) whether ibotenate-stimulated PPI hydrolysis would be lastingly enhanced in the hippocampus (HIPP) and AM/PC of the HIPP-kindled rats and (2) whether similar changes would be found in the early stage of HIPP kindling. Although ibotenate-stimulated accumulation of [3H]inositol 1-phosphate ([ 3H]IP1) increased significantly in the HIPP 24 h, 5 days, and 15 days after the last seizure of fully developed HIPP-kindled rats, no statistically significant increase was found in the HIPP 30 days after the last seizure. In the AM/PC, 10(-3) M ibotenate-stimulated [3H]IP1 accumulation significantly increased by 91%, 91%, 86% and 90%, 24 h, 5 days, 15 days and 30 days after the last seizure, respectively. There was no significant increase in ibotenate-stimulated [3H]IP1 accumulation 7 days after the last stimulation in the HIPP and AM/PC of rats which had undergone electrical stimulation only 5 times in the HIPP. These results indicate that (1) PPI hydrolysis coupled to excitatory amino acid receptors increases long-lastingly in the AM/PC regardless of the primary kindled site, and (2) these changes do not occur in the early stage of HIPP-kindling.
Yamada
N
N
Department of Neuropsychiatry, Okayama University Medical School, Japan.
Akiyama
K
K
Otsuki
S
S
D000679:Amygdala / Q000378:metabolism* / Q000503:physiopathology; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism* / Q000503:physiopathology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D007051:Ibotenic Acid / Q000494:pharmacology*; D007696:Kindling, Neurologic; D008297:Male; D010080:Oxazoles / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D010080:Oxazoles; D010716:Phosphatidylinositols; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D007051:Ibotenic Acid