Gut/brain peptides in the genital tract: VIP and PACAP

The two structurally related gut/brain peptides vasoactive intestinal polyp eptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) are pleiotropic peptides with a wide-spread occurrence. Besides their pres ence and functions in the gut and the brain VIP and PACAP have distinct phy siological roles in the genital tract. VIP seems to be involved in the nerv ous control of ovum transportation, sexual arousal in women and penile erec tion in men. Dysfunction of the VIP nerves can lead to erectile failure and VIP in combination with phentolamine can be successfully used as self-inje ction therapy of impotence. PACAP could be a co-transmitter with VIP in a n umber of functions involving nervous control of blood flow and motility, bu t in addition PACAP is a sensory neurotransmitter. The most fascinating rol e for PACAP is, however, its auto- or paracrine function in the peri- and p ostovulatory events involving acute progesterone production and subsequent luteinization in periovulatory granulosa/lutein cells.