PKC‐independent inhibition of glutamate exocytosis by arachidonic acid in rat cerebrocortical synaptosomes

Abstract
In rat cerebrocortical synaptosomes, the addition of 4β‐phorbol dibutyrate (4β‐PDBu) and arachidonic acid enhances and decreases, respectively, the glutamate release evoked by 4‐aminopyridine. Pretreatment of synaptosomes with 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) or preincubation with staurosporine, prevent the stimulatory effect of 4β‐PDBu, but are without effect on the inibitory action of arachidonic acid. Moreover, methyl arachidonate, which is not effective as a PKC activator, also strongly inhibits glutamate exocytosis. These results suggest that PKC is not involved in the inhibition of glutamate release by arachidonic acid.