Differential expression of A- and B-subtypes of cholecystokinin/gastrin receptors in the developing calf pancreas.
Cholecystokinin (CCK)/gastrin receptors were characterized in calf pancreatic plasma membranes from newborns, 28- and 119-day-old milk-fed preruminants, and 119-day-old weaned ruminants. Scatchard analysis of [125I]Bolton-Hunter reagent-[Thr28,Nle31]CCK-(25-33) binding indicated two classes of binding sites: high affinity sites exhibited significant higher affinity and binding capacity (P < 0.05) in 119-day-old ruminants than in 119-day-old preruminants (Kd = 0.13 +/- 0.02 vs. 0.35 +/- 0.08 nM; binding capacity (Bmax) = 53 +/- 12 vs. 18 +/- 5 fmol/mg protein). Pharmacological analysis using selective agonists and antagonists indicated the expression of the CCK-A receptor at birth, whereas the CCK-B receptor predominated at postnatal stages. At all stages, the binding was inhibited by guanosine 5'-[gamma-thio]triphosphate. Binding site identification by photoaffinity labeling showed that at birth, the labeling occurred mainly on a 78- to 96-kilodalton (kDa) component. In milk-fed animals, aged 28 and 119 days, two membrane-binding components were labeled at 78-96 and 43-52 kDa. In 119-day-old ruminants, labeling occurred mainly on a 40- to 47-kDa protein. Deglycosylation by endo-beta-N-acetylglucosaminidase-F of the 40- to 47- and 43- to 52-kDa components resulted in the formation of a 37-kDa membrane protein. Consequently, this study demonstrated 1) the differential expression of CCK-A and -B receptors in developing calf pancreas, 2) the predominance of CCK-B receptors in normal pancreas, and 3) the maturation of CCK-B receptors during the weaning period, which includes the glycosylation level. These results suggest that CCK may play a predominant role during the early postnatal development, while gastrin and CCK-B receptors can function progressively to regulate proliferation and exocrine secretion in the calf pancreas, especially from the weaning period.
Le Meuth
V
V
Laboratoire du Jeune Ruminant, Institut National de la Recherche Agronomique, Rennes, France.
Philouze-Rome
V
V
Le Huerou-Luron
I
I
Formal
M
M
Vaysse
N
N
Gespach
C
C
Guilloteau
P
P
Fourmy
D
D
D000345:Affinity Labels; D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001665:Binding Sites; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002766:Cholecystokinin / Q000031:analogs & derivatives / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology; D005755:Gastrins / Q000378:metabolism; D006031:Glycosylation; D007202:Indicators and Reagents; D007700:Kinetics; D010179:Pancreas / Q000254:growth & development* / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010777:Photochemistry; D011949:Receptors, Cholecystokinin / Q000378:metabolism*; D013388:Succinimides
D000345:Affinity Labels; D005755:Gastrins; D007202:Indicators and Reagents; D010446:Peptide Fragments; D011949:Receptors, Cholecystokinin; D013388:Succinimides; C083040:gastrin desulfonated; C022581:Bolton-Hunter reagent; C042874:cholecystokinin (25-33), Thr(28)-Nle(31)-; D002766:Cholecystokinin; D019204:GTP-Binding Proteins