Ghrelin is not suppressed in hyperglycemic clamps by gastric inhibitory polypeptide and arginine.
Systemic ghrelin concentration falls rapidly after nutrient ingestion in vivo. The effect incretins on ghrelin secretion in humans remains unclear. We quantified circulating ghrelin concentrations under hyperglycemic conditions combined with infusion of gastric inhibitory polypeptide (GIP) and arginine.


METHODS
Eight healthy volunteers were studied with a hyperglycemic clamp followed by addition of GIP (2 pmol.kg(-1).min(-1), 60-115 min) and an arginine-bolus and -infusion (10 mg.kg(-1).min(-1), 90-115 min).


RESULTS
Hyperglycemia alone increased circulating insulin concentrations (p<0.01), and decreased ghrelin concentrations to 89.8% of basal (p=0.208). GIP-infusion resulted in circulating insulin concentration of 1109+/-942 pmol/l (p<0.02) and no further decrease of ghrelin (86.2% of baseline, p=0.050). Under arginine- and GIP-infusion together, insulin concentrations increased progressively to 3005+/-1604 pmol/l (p<0.01) without further decreasing in ghrelin concentrations (98.9% of baseline, p=0.575).


CONCLUSIONS
Hyperglycemic hyperinsulinemia and further increases of hyperinsulinemia to supraphysiological and high supraphysiological concentrations under GIP- and arginine-infusion do not significantly decrease ghrelin concentrations in healthy subjects. Moreover, there is no dose-dependent suppression of ghrelin by insulin in the hyperglycemic condition. Neither GIP nor arginine affected ghrelin release.
Rudovich
Natalia N
NN
Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Street 114-116, 14558 Nuthetal, Germany.
Dick
D
D
Moehlig
M
M
Otto
B
B
Spranger
J
J
Rochlitz
H J
HJ
Ristow
M
M
Tschoep
M
M
Pfeiffer
A F H
AF
D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000008:administration & dosage / Q000378:metabolism*; D054439:Ghrelin; D015309:Glucose Clamp Technique; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D008297:Male; D036361:Peptide Hormones / Q000097:blood*
D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D005749:Gastric Inhibitory Polypeptide; D001120:Arginine