Ghrelin and the enteroinsular axis in healthy men.
OBJECTIVE
Ghrelin, a potent stimulator of GH secretion, also acts as an orexigenic hormone. Plasma ghrelin levels rise before meals with postprandial reduction, suggesting that circulating levels of enteroinsular hormones might influence ghrelin secretion.


OBJECTIVE
The aim of this study was to evaluate the effects of ghrelin on enteroinsular hormones in healthy men.


METHODS
Three tests were performed on 3 different days in 6 healthy men: On the first day, saline was infused from 0-120 minutes followed by a ghrelin bolus (1 microg/kg) administration (Test 1); on the second experimental day, GHRH was administered at 0 min, and a ghrelin bolus was given at 120 min (Test 2); on the third experimental day, GHRP-6 was administered at 0 min, followed by a ghrelin bolus at 120 min (Test 3). Plasma glucose, insulin, proinsulin, C-Peptide Glucagone Like Peptide one (GLP-1) determined at 0, 15, 30, 60, 90, and 120 min of the test period.


RESULTS
There was a significant increase in AUC glucose (526.41+/-22.91 mmol . ml(-1) . min vs. 566.37+/-15.64 mmol . ml(-1) . min; p<0.05) and AUC insulin (756.25+/-107.56 mU . ml(-1) . min vs. 981.62+/-180.32 mU . ml(-1) . min; p<0.05) and a significant decrease in AUC GLP-1 (2346.87+/-874.28 pmol . ml(-1) . min vs. 1769.5+/-784 pmol . ml(-1) . min; p<0.05) after ghrelin administration in Test 1 compared to Test 3. There was a mild but non-significant increase in AUC for insulin, proinsulin, and C-Peptide and a mild reduction in AUC GLP-1 after every ghrelin administration.


CONCLUSIONS
There was no evidence of a direct effect of ghrelin administration on enteroinsular hormone levels in this study. However, ghrelin may potentiate the glucose-insulin stimulatory effects of GHRP-6. More studies should be carried out for further evaluation of ghrelin-enteroinsular hormones interplay.
Institute of Endocrinology, Diabetes and Diseases of Metabolism, Clinical Center of Serbia, Belgrade, Serbia. micicd@eunet.yu
Dragan
D
Micic
Leonidas
L
Duntas
Goran
G
Cvijovic
Aleksandra
A
Kendereski
Mirjana
M
Sumarac-Dumanovic
Peter
P
Jehle
Svetlana
S
Zoric
Danica
D
Pejkovic
Mary
M
Lague
Carlos
C
Dieguez
Felipe
F
Casanueva
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D054439:Ghrelin / Q000008:administration & dosage / Q000502:physiology*; D005934:Glucagon / Q000097:blood*; D052216:Glucagon-Like Peptide 1 / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage; D006801:Humans; D007328:Insulin / Q000097:blood*; D007700:Kinetics; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage; D011384:Proinsulin / Q000097:blood
D001786:Blood Glucose; D002096:C-Peptide; D054439:Ghrelin; D007328:Insulin; D009842:Oligopeptides; C041048:growth hormone releasing hexapeptide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D013007:Growth Hormone-Releasing Hormone; D011384:Proinsulin