Neuropeptide Y inhibits vasoactive intestinal peptide-stimulated adenylyl cyclase in rat ventral prostate

Neuropeptide Y (NPY), a peptide present in the prostate gland, was found to inhibit vasoactive intestinal peptide (VIP)-stimulated cyclic AMP accumulation in isolated rat prostatic epithelial cells as well as VIP-stimulated adenylyl cyclase activity in rat prostatic membranes. The inhibitory effect of NPY was selective for the VIP receptor/effector system since it was also observed when using pituitary adenylyl cyclase activating peptide (PACAP-27) which presumably recognizes VIP receptors in this gland, but not when using unrelated substances such as isoproterenol or forskolin. NPY did not modify either the general lipid membrane microviscosity or the VIP-receptor binding. The inhibitory effect of VIP was blocked by pretreatment of the prostatic membranes with pertussis toxin. These results suggest the presence of NPY receptors in rat ventral prostate coupled in an inhibitory manner to adenylyl cyclase through a guanine nucleotide regulatory Gi protein.