Prostaglandin involvement in the evoked release of D-aspartate from cerebellar mossy fiber terminals.

Isolated cerebellar glomeruli, containing mossy fiber terminals, were used to investigate the mechanisms involved in the evoked release of acid amino acids. The glomeruli contain a high affinity uptake system for D-aspartate, with a KT of 384 pmol/mg protein/min and the incorporated D-[3H]aspartate was released in response to various depolarizing agents, as well as exogenous arachidonic acid and prostaglandins. There was a marked inhibition of the release evoked by high K+ and exogenous arachidonate when the cyclooxygenase inhibitor ibuprofen was present. Also, exposure of the glomeruli to depolarizing conditions resulted in an increase in the amount of unesterified [3H]arachidonate. It appears that accumulation of unesterified arachidonate and subsequent production of prostaglandins are involved in the evoked release of the acidic amino acids from cerebellar mossy fiber terminals.