Long-lasting enhancement of metabotropic excitatory amino acid receptor-mediated polyphosphoinositide hydrolysis in the amygdala/pyriform cortex of deep prepiriform cortical kindled rats.
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.
Akiyama
K
K
Department of Neuropsychiatry, Okayama University Medical School, Japan.
Daigen
A
A
Yamada
N
N
Itoh
T
T
Kohira
I
I
Ujike
H
H
Otsuki
S
S
D000679:Amygdala / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D003515:Cycloleucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004558:Electric Stimulation; D006868:Hydrolysis; D007051:Ibotenic Acid / Q000494:pharmacology*; D007536:Isomerism; D007696:Kindling, Neurologic; D008032:Limbic System / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology*; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D012640:Seizures / Q000378:metabolism
D009498:Neurotoxins; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D017981:Receptors, Neurotransmitter; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D007051:Ibotenic Acid