Isolation and molecular characterization of porcine calcitonin gene-related peptide (CGRP) and its endocrine effects in the porcine pancreas.
The aim of this study was to investigate the possible role of porcine calcitonin gene-related peptide (CGRP) in the regulation of the endocrine porcine pancreas. Initially, we isolated and purified CGRP from extracts of porcine adrenal glands and pancreases. A single molecular form of the peptide was found in the two tissues. The adrenal peptide was sequenced and found to differ from human alpha-CGRP at six positions and from human beta-CGRP at three positions. By immunohistochemistry, CGRP was found in nerve fibers in the pancreatic ganglia. A synthetic replica of the porcine peptide was infused at different dose levels (10(-10), 10(-9), and 10(-8) M) into isolated perfused porcine pancreata. With 5 mmol/L glucose in the perfusate. CGRP at 10(-10) and 10(-9) M increased insulin and glucagon secretion, whereas significant decreases were observed with 10(-8) M. Somatostatin secretion was increased significantly by 10(-8) M CGRP. In immunoneutralization studies (n = 6) using a high-affinity somatostatin antibody, the inhibitory effect of CGRP at 10(-8) M was reversed to a significant stimulation of insulin and glucagon secretion. Insulin secretion in response to square-wave increases in glucose concentration to 11 mM was inhibited dose dependently by CGRP; at 10(-8) M the insulin output decreased by 72+/-9% (n = 6). The present results indicate that CGRP may be involved in the regulation of insulin and glucagon secretion from the porcine pancreas.
Rasmussen
T N
TN
Department of Medical Physiology, The Panum Institute, University of Copenhagen, Denmark.
Bersani
M
M
Schmidt
P
P
Thim
L
L
Kofod
H
H
Jørgensen
P N
PN
Poulsen
S S
SS
Holst
J J
JJ
D000311:Adrenal Glands / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology*; D005934:Glucagon / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D008969:Molecular Sequence Data; D009412:Nerve Fibers / Q000737:chemistry; D010179:Pancreas / Q000737:chemistry* / Q000187:drug effects* / Q000294:innervation; D017385:Sequence Homology; D013004:Somatostatin / Q000037:antagonists & inhibitors / Q000378:metabolism; D013552:Swine
D000906:Antibodies; D007328:Insulin; D013004:Somatostatin; D005934:Glucagon; D015740:Calcitonin Gene-Related Peptide