[Vasoactive intestinal polypeptide: a potential neurotransmitter]

A review of current advances in anatomy, physiology and pharmacology of vasoactive intestinal polypeptide (VIP) is presented. VIP is a basic 28-aminoacid peptide of molecular weight 3300. Nerves immunoreactive to VIP are in the heart, lung, digestive and genitourinary tract, eye, skin, ovaries and thyroid gland. In the central nervous system VIP-ergic neurons are found primarily in telencephalic areas. Here, VIP provokes the excitation, vasodilatation and together with noradrenaline participates in the regulation of cortical energy metabolism. VIP-ergic neurons are mainly present in afferent pathways of the spinal cord with higher density in the sacral segments. Anatomic distribution of VIP-ergic neurons suggests involvement in pain transmission and integration of the sacral autonomic reflex pathways. The biologic effects of VIP in periphery are the vasodilatation, relaxation of smooth muscle and influence on exocrine glands secretion. In the endocrine system VIP stimulates the secretion of different hormones (prolaction, growth hormone, oxytocin, vasopressin, ovarial and thyroid hormones). VIP-ergic innervation is changed in some organs during the diseases of those organs. Practical exploatation of this knowledge is limited at present because effective, non-polypeptide agonists and antagonists are not available yet.