The synergism between ACPD and arachidonic acid on glutamate release in hippocampus is age-dependent.

Activation of the metabotropic glutamate receptor by the specific agonist trans-1-amino-cyclopentyl-1,3-dicarboxylate (ACPD) increases release of glutamate and activation of protein kinase C in the presence of a low concentration of arachidonic acid in hippocampal synaptosomes prepared from 4-month-old rats. The data presented indicate an age-related decrease in both [3H]glutamate release and protein kinase C activation and an age-related decrease in the release response to arachidonic acid and ACPD, with no corresponding change in protein kinase C activation. The finding that the interaction between arachidonic acid and ACPD on release was absent in synaptosomes prepared in the presence of heparin, an antagonist at inositol trisphosphate receptors, suggests that mobilization of intracellular calcium stores plays a role in the synergism between arachidonic acid and ACPD on [3H]glutamate release in hippocampal synaptosomes.