Stimulation of Cyclic AMP Formation by Pituitary Adenylate Cyclase-Activating Polypeptide Is Attenuated by Glutamate in Rat Brain Slices

In rat hippocampal slices, pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) stimulated cyclic AMP formation in dose- and time-dependent manners. The PACAP-38 action was dose-dependently attenuated by L-glutamate in the hippocampus; L-glutamate at the concentration of 1 mM attenuated PACAP-38-stimulated cyclic AMP formation by approximately 30%. The inhibitory effect of L-glutamate is also observed in rat cerebellar slices. In contrast, the inhibitory effect of a prostanoid EP3- receptor agonist on PACAP-38-stimulated cyclic AMP formation was brain region-specific; the inhibitory action was observed in the cerebellum but not in the hippocampus.