Effect of GLP-1 (glucagon-like peptide 1:7-36 amide) on porcine pancreatic endocrine cell proliferation and insulin secretion.
BACKGROUND
We have established a method of isolation and primary monolayer culture of porcine pancreatic endocrine (PE) cells using nicotinamide. Recently, several insulin-stimulating factors have been recognized as modifying the function of endocrine cells. Glucagon-like peptide 1 (GLP-1), derived from intestinal cells, is one of the substances that may regulate insulin secretion and cell proliferation.


OBJECTIVE
The aim of the current study was to examine the effect of GLP-1 on PE cell proliferation and insulin secretion in our culture system.


METHODS
The PE cells were prepared by nonenzymatic digestion and cultured in media with or without 10 nmol/L GLP-1 and maintained for 15 days. Basal insulin secretion and the glucose stimulated-response were observed by enzyme assay. PE-cell proliferation was assessed using 5-bromo 2' deoxyuridine (BrdU). beta-Cell specificity was confirmed by double staining with anti-BrdU and insulin antibody. mRNA expression in PE cells for insulin and pancreatic and duodenal homeobox gene 1 (PDX-1), a transcription factor, was semiquantitated by a real-time PCR method.


RESULTS
Neither baseline nor glucose-stimulated insulin secretion differed significantly with or without the addition of 10 nmol/L GLP-1. However, significant changes of insulin secretion were observed in doses up to 100 nmol/L of GLP-1. BrdU incorporation increased with 10 nmol/L GLP-1 from 2.35+/- 0.16% to 9.11+/- 0.53% as compared with the control (from 2.17 +/- 0.57% to 6.13 +/- 0.35%). This increase was observed after a 12-day culture period. Double staining identified well-preserved insulin-containing cells, but neither the number of positive cells nor staining intensity differed significantly between the 2 groups during the 15-day culture period. The level of mRNA expression for both insulin and PDX-1 increased slightly but significantly.


CONCLUSIONS
GLP-1 has a proliferative effect on PE cells and affects gene expression in short-term culture.
Nagai
Kazutaka
K
Department of Medicine IV, Kidney Center, Tokyo Women's Medical University, Tokyo, Japan.
Tsuchiya
Ken
K
Ezaki
Taichi
T
Tsuchiya
Mariko
M
Ohgawara
Hisako
H
D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005934:Glucagon; D052216:Glucagon-Like Peptide 1; D004763:Glucagon-Like Peptides; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013552:Swine
D007328:Insulin; D010446:Peptide Fragments; D012333:RNA, Messenger; C055453:glucagon-like peptide 1 (7-36)amide; D004763:Glucagon-Like Peptides; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D005947:Glucose; D011188:Potassium