THE SYNERGISM BETWEEN ACPD AND ARACHIDONIC-ACID ON GLUTAMATE RELEASE IN HIPPOCAMPUS IS AGE-DEPENDENT

Activation of the metabotropic glutamate receptor by the specific agon ist trans-1-amino-cyclopentyl-1,3-dicarboxylate (ACPD) increases relea se of glutamate and activation of protein kinase C in the presence of a low concentration of arachidonic acid in hippocampal synaptosomes pr epared from 4-month-old rats. The data presented indicate an age-relat ed decrease in both [H-3]glutamate release and protein kinase C activa tion and an age-related decrease in the release response to arachidoni c acid and ACPD, with no corresponding change in protein kinase C acti vation. 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 [H-3]glutamate release in hippocampal synaptosomes.