Functional maturation of fetal porcine beta-cells by glucagon-like peptide 1 and cholecystokinin.
Fetal beta-cells are immature in their responsiveness to glucose, and maturation occurs after oral feeding commences at birth. The incretin hormones glucagon-like peptide 1 (GLP-1) and cholecystokinin (CCK) are known to be released from the gut in response to oral feeding and enhance insulin secretion from pancreatic beta-cells. We hypothesized that these fetal beta-cells would mature in their glucose responsiveness if they were previously exposed to incretins. We exposed fetal pig islet-like cell clusters (ICCs) to 100 nM GLP-1, 5 micro M CCK, or 10 mM nicotinamide (NIC; a positive control) for 6 h and demonstrated 3- and 1.7-fold increases in glucose-induced insulin secretion for GLP-1 and CCK, respectively. This effect did not reach statistical significance if the ICCs were exposed to the incretins for 3 d. However, exposure for 4 d enhanced formation of beta-cells from undifferentiated cells, from 8 +/- 1% (controls) to 17 +/- 3% for GLP-1, 20 +/- 4% for CCK, and 15 +/- 1 for NIC (P < 0.001). ICCs exposed to GLP-1 for 3 d also showed a 1.9-fold increase in the intensity of PDX-1(+) cells, as assessed by semiquantitative fluorescent immunocytochemistry. Exposure of ICCs to incretins for 3 d did not show any increase in size of the islet clusters. ICCs exposed to either incretin as well as controls were transplanted into severe combined immunodeficient mice and examined at 1 and 2 months. We found a significant increase in the number of beta-cells in the GLP-1- and NIC-treated groups compared with the untreated controls or CCK. Perfusion of these grafts at 2 months showed that ICCs previously exposed to GLP-1, CCK, and NIC (but not controls), were functional and mature. In conclusion, GLP-1 and CCK have a dual effect on fetal pig ICCs, causing maturation of glucose-induced insulin secretion from beta-cells as well as enhancement of differentiation from undifferentiated precursors.
Diabetes Transplant Unit, Prince of Wales Hospital and University of New South Wales, Sydney, New South Wales 2031, Australia. anand_hardikar@nih.gov
Anandwardhan A
AA
Hardikar
Xiao Yang
XY
Wang
Lindy J
LJ
Williams
Juliana
J
Kwok
Rose
R
Wong
Mu
M
Yao
Bernard E
BE
Tuch
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division; D048429:Cell Size; D002766:Cholecystokinin / Q000494:pharmacology*; D046508:Culture Techniques; D005455:Fluorescent Antibody Technique; D005934:Glucagon / Q000494:pharmacology*; D052216:Glucagon-Like Peptide 1; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000032:analysis; D007515:Islets of Langerhans / Q000737:chemistry / Q000187:drug effects* / Q000196:embryology*; D016381:Islets of Langerhans Transplantation; D009536:Niacinamide / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D011498:Protein Precursors / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D013997:Time Factors
D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D009536:Niacinamide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D002766:Cholecystokinin; D005947:Glucose