The synergism between metabotropic glutamate receptor activation and arachidonic acid on glutamate release is occluded by induction of long-term potentiation in the dentate gyrus.
In synaptosomes prepared from dentate gyrus, activation of the metabotropic glutamate receptor by the specific agonist, trans-1-amino-cyclopentyl-1,3-dicarboxylate, increases release of glutamate in the presence of a low concentration of arachidonic acid. A similar interaction between trans-1-amino-cyclopentyl-1,3-dicarboxylate and arachidonic acid is observed on inositol phospholipid turnover and on protein kinase C activity. We report here that when long-term potentiation is induced in the dentate gyrus by high frequency tetanic stimulation to the perforant path, the synergism between arachidonic acid and trans-1-amino-cyclopentyl-1,3-dicarboxylate is occluded. The occlusion of the synergistic action between arachidonic acid and trans-1-amino-cyclopentyl-1,3-dicarboxylate on glutamate release extended to occlusion of the effect in inositol phospholipid turnover and protein kinase C activation in synaptosomes prepared from dentate gyrus in which long-term potentiation was induced in vivo. One interpretation of the results presented here is that tetanic stimulation is followed by stimulation of metabotropic glutamate receptors at a time when arachidonic acid concentration in the synaptic region is elevated, and that this interaction triggers the presynaptic changes required for expression of long-term potentiation.
McGahon
B
B
Department of Physiology, Trinity College, Dublin, Ireland.
Lynch
M A
MA
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D018891:Dentate Gyrus / Q000187:drug effects* / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects*; D013997:Time Factors
D018094:Receptors, Metabotropic Glutamate; D016718:Arachidonic Acid; D018698:Glutamic Acid