Effects of PACAP(1-27) on the canine endocrine pancreas in vivo: interaction with cholinergic mechanism.
The aim of the present study was to characterize the effects of pituitary adenylate cyclase activating polypeptide (PACAP) on the endocrine pancreas in anesthetized dogs. PACAP(1-27) and a PACAP receptor (PAC(1)) blocker, PACAP(6-27), were locally administered to the pancreas. PACAP(1-27) (0.005-5 microg) increased basal insulin and glucagon secretion in a dose-dependent manner. PACAP(6-27) (200 microg) blocked the glucagon response to PACAP(1-27) (0.5 microg) by about 80%, while the insulin response remained unchanged. With a higher dose of PACAP(6-27) (500 microg), both responses to PACAP(1-27) were inhibited by more than 80%. In the presence of atropine with an equivalent dose (128.2 microg) of PACAP(6-27) (500 microg) on a molar basis, the insulin response to PACAP(1-27) was diminished by about 20%, while the glucagon response was enhanced by about 80%. The PACAP(1-27)-induced increase in pancreatic venous blood flow was blocked by PACAP(6-27) but not by atropine. The study suggests that the endocrine secretagogue effect of PACAP(1-27) is primarily mediated by the PAC(1) receptor, and that PACAP(1-27) may interact with muscarinic receptor function in PACAP-induced insulin and glucagon secretion in the canine pancreas in vivo.
Yamaguchi
Nobuharu
N
Groupe de recherche sur le système nerveux autonome (GRSNA), Faculté de pharmacie, Université de Montréal, Montréal, QC H3C 3J7, Canada. nobuharu.yamaguchi@umontreal.ca
Minassian
Tamar Rita
TR
Yamaguchi
Sanae
S
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005934:Glucagon / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism
D007328:Insulin; D018727:Muscarinic Antagonists; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D001285:Atropine; D005934:Glucagon