Mechanisms of action of VIP and PACAP in the stimulation of insulin release.
VIP and PACAP stimulate insulin release by interaction with the VIP-2/PACAP-3 receptor on the beta cell. Activation of the receptor results in Gs-mediated stimulation of adenylyl cyclase and increased cellular cyclic AMP levels. Increased cyclic AMP results in a small and transient increase in [Ca2+]i, which is likely to have only a small and transient effect on the secretion rate. Cyclic AMP also potentiates insulin secretion by an as yet unknown action at a distal site. A third action of VIP and PACAP is responsible for the continued stimulation of insulin secretion after the levels of cyclic AMP and [Ca2+]i have returned to basal values. This third pathway, which is identified at present only by its sensitivity to low concentrations of wortmannin, plays a major role in the prolonged stimulation of insulin release by VIP and PACAP.
Straub
S G
SG
Department of Pharmacology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA. sgs4@cornell.edu or gws2@cornell.edu
Sharp
G W
GW
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D007329:Insulin Antagonists / Q000494:pharmacology; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone / Q000502:physiology; D018005:Receptors, Vasoactive Intestinal Peptide / Q000502:physiology; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D000077191:Wortmannin
D000730:Androstadienes; D007328:Insulin; D007329:Insulin Antagonists; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D005576:Colforsin; D014660:Vasoactive Intestinal Peptide; D000242:Cyclic AMP; D005947:Glucose; D002118:Calcium; D000077191:Wortmannin