Ibotenate stimulates glutamate release from guinea pig cerebrocortical synaptosomes: inhibition by L-2-amino-4-phosphonobutyrate (L-AP4).
Ibotenate induced a concentration- and largely calcium-dependent release of endogenous glutamate from guinea pig cerebro-cortical synaptosomes. In the absence of Mg2+, the response to ibotenate was enhanced through a mechanism involving N-methyl-D-aspartate (NMDA) receptors; this component was sensitive to the NMDA antagonist 2-amino-7-phosphonoheptanoate (AP7). In the presence of Mg2+, the ibotenate-induced Ca2(+)-dependent release was abolished by L-2-amino-4-phosphonobutyrate (L-AP4). It is suggested that presynaptic 'L-AP4 receptors' exist in guinea pig cerebral cortex, at which ibotenate acts to facilitate glutamate release. L-AP4 may act as an antagonist, or partial agonist of weak intrinsic activity.
Jones
P G
PG
Department of Physiology and Pharmacology, University of Southampton, U.K.
Roberts
P J
PJ
D000613:Aminobutyrates / Q000494:pharmacology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006168:Guinea Pigs; D007051:Ibotenic Acid / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D000613:Aminobutyrates; D005971:Glutamates; D009498:Neurotoxins; D018377:Neurotransmitter Agents; D010080:Oxazoles; D007051:Ibotenic Acid; D018698:Glutamic Acid; C012729:2-amino-4-phosphonobutyric acid