T. Onaga et al., EFFECT OF PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE ON EXOCRINE AND ENDOCRINE SECRETION IN THE OVINE PANCREAS, Comparative biochemistry and physiology. Part C, Pharmacology toxicology & endocrinology, 115(3), 1996, pp. 185-193
The role of pituitary adenylate cyclase-activating polypeptide (PACAP)
in the regulation of exocrine and endocrine pancreas was investigated
in conscious sheep. Intravenous infusions of PACAP-27 and PACAP-38 (1
, 3, and 10 pmol/kg/min) for 10 min during phase II of the duodenal mi
grating myoelectric complex accelerated pancreatic protein and amylase
outputs dose-dependently. The responses in enzyme secretion to both P
ACAPs at the highest doses were inhibited significantly by atropine in
fusion (14.4 nmol/kg/min). Vasoactive intestinal polypeptide (VIP) at
3 pmol/kg/min significantly accelerated protein but not amylase output
s, although the response to the highest dose was not significantly inf
luenced by atropine. PACAP-27 and VIP increased pancreatic juice flow
and bicarbonate output dose-dependently; however, the responses to the
highest dose were not altered significantly by atropine. On the other
hand, intravenous injection of PACAP-38 (100 pmol/kg) did not influen
ce basal plasma concentration of insulin, glucagon, and glucose. Moreo
ver, PACAP 38 (1-100 pmol/kg) altered neither pancreatic endocrine res
ponse to intravenous infusion of glucose (20 mu mol/kg/min) not that t
o n-butyric acid (33 mu mol/kg/min). These results suggest that PACAP
contributes to the regulation of exocrine secretion of the ovine pancr
eas but not to endocrine secretion. PACAP appears to accelerate pancre
atic enzyme secretion mostly via the cholinergic nerves. Copyright (C)
1996 Elsevier Science Inc.