Effect of oral glucose on the late growth hormone rise and growth hormone responses to GHRH in normal subjects.
A late rise in serum GH occurs 3-5 h following oral glucose in man. In order to investigate the mechanisms through which this occurs we have studied the late GH rise after oral glucose during administration of a supramaximal dose of GHRH. In eight normal subjects, oral glucose (100 g) greatly enhanced the GH responses to a supramaximal dose of GHRH (50 micrograms bolus, followed immediately by 100 micrograms/h infusion for 3 h) given 3.5 h after the glucose. GH peak (mean +/- SEM) elicited by GHRH (bolus + infusion) rose from 55.2 +/- 20.4 to 133.4 +/- 29.6 mU/l (P less than 0.02) after glucose pretreatment. In conclusion, it is likely that the late rise in GH secretion induced by oral glucose occurs via a non-GHRH-dependent mechanism. These data are consistent with the hypothesis that the delayed GH response to glucose is a consequence of reduced release of somatostatin from the hypothalamus.
Valcavi
R
R
Department of Medicine, University of Wales College of Medicine, Cardiff, UK.
Zini
M
M
Dieguez
C
C
Portioli
I
I
Scanlon
M F
MF
D000284:Administration, Oral; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D004311:Double-Blind Method; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011863:Radioimmunoassay
D001786:Blood Glucose; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D005947:Glucose