Roles and mechanisms of action of pituitary adenylate cyclase-activating polypeptide (PACAP) in growth hormone and prolactin secretion.

It appears that PACAP has a direct action on somatotrophs to releaase GH. The intracellular signal transduction mechanisms for PACAP might be similar to but partly distinct from those for GRH. PACAP might play a role in GH secretion induced by serotoninergic mechanisms but not in ultradian rhythm of GH secretion in the rat. PACAP can stimulate PRL release from the pituitary in rats possibly through indirect paracrine effect. In addition, PACAP might participate in regulation of PRL secretion via hypothalamic VIP.