Inhibition of anterior pituitary prostaglandin-stimulated adenylyl cyclase activity by somatostatin

Abstract

Rat anterior pituitary gland adenylyl cyclase activity is stimulated by prostaglandins with an order of potency of [Formula: see text] which is the same for cAMP accumulation and growth hormone release. Somatostatin inhibited prostaglandin-stimulated adenylyl cyclase with an ID50 of 1.48 × 10−8 ± 0.27 × 10−8 M. GTP also stimulated adenylyl cyclase activity at concentrations greater than 10−6 M but did not prevent inhibition by somatostatin. These results indicate that at least one action of somatostatin is exerted directly on cAMP formation.