Evidence for a functional role of the cholecystokinin-B/gastrin receptor in the human fetal and adult pancreas.
Gastrin (G) and cholecystokinin (CCK) are gastrointestinal neuropeptides that are released into circulation during a meal. G is also transiently expressed during embryogenic and early ontogenic development of the pancreas and is believed to act on islet-cell development. Both peptides act on pancreatic endocrine function; however, the effects are dependent on the species and on cellular and molecular underlying mechanisms that remain poorly characterized. Since CCK-B/G subtype receptor is predominant over the CCK-A subtype in the human pancreas, we hypothesized that it could be expressed by islet cells. Here we present reverse transcription-polymerase chain reaction and immunohistochemistry data demonstrating that the CCK-B/G receptor is expressed in islet cells and that islet glucagon-producing cells are the major site of CCK-B/G receptor expression in adult and fetal pancreas. Moreover, G immunoreactivity was detected in the fetal human pancreas at embryogenic week 22. G- and CCK-stimulated glucagon are released from purified human islets. Concentration of CCK and G eliciting a half-maximal level of glucagon secretion were 13 +/- 6 and 8 +/- 5 pmol/l, respectively. Maximal glucagon secretion was achieved in the presence of 30 pmol/l peptides and was similar to that obtained in the presence of 10 mmol/l L-arginine (1.6 pmol x ml(-1) x 90 min(-1)). The nonpeptide antagonist of the CCK-B/G receptor, RPR-101048, fully inhibited CCK- and G-stimulated glucagon secretion at 100 nmol/l concentration. These data are consistent with the view that the CCK-B/G receptor is involved in glucose homeostasis in adult humans and mediates the autocrine effects of G on islet differentiation and growth in the fetal pancreas.
Saillan-Barreau
C
C
INSERM U151, Institut Louis Bugnard, CHU Rangueil, Toulouse, France.
Dufresne
M
M
Clerc
P
P
Sanchez
D
D
Corominola
H
H
Moriscot
C
C
Guy-Crotte
O
O
Escrieut
C
C
Vaysse
N
N
Gomis
R
R
Tarasova
N
N
Fourmy
D
D
D000328:Adult; D002478:Cells, Cultured; D002766:Cholecystokinin / Q000378:metabolism; D003001:Cloning, Molecular; D005755:Gastrins / Q000378:metabolism; D005786:Gene Expression Regulation; D005934:Glucagon / Q000378:metabolism; D006801:Humans; D010179:Pancreas / Q000196:embryology / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin / Q000235:genetics / Q000502:physiology*
D005755:Gastrins; D012333:RNA, Messenger; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin; D005934:Glucagon; D002766:Cholecystokinin