Effect of obesity and feeding on the growth hormone (GH) response to the GH secretagogue L-692,429 in young men.
GH secretion and the response to GH secretagogues are significantly diminished in obese individuals. Previous studies have shown that L-692,429 (L), a nonpeptide mimetic of GH-releasing peptide, selectively stimulates GH release in normal young men and in the elderly, who also have diminished GH secretion. A paired, two-site study examined the effects of L on GH release in 12 healthy obese (part A; mean +/- SD: age, 26.1 +/- 3.3 yr; body mass index, 35.0 +/- 3.1 kg/m2) and 10 nonobese (part B; age, 22.2 +/- 2.3 yr; body mass index, < or = 27.0) young men. In part A, placebo, low dose L (0.2 mg/kg), or high dose L (0.75 mg/kg) was administered iv over 15 min on 3 separate occasions after an overnight fast. Samples for GH, PRL, and cortisol determinations were obtained every 15 min. GH release (mean +/- SE) was significantly increased by both doses of L compared to the effect of placebo: 12.6 +/- 1.8 micrograms/L (low dose), 18.5 +/- 2.7 micrograms/L (high dose), and 0.84 +/- 0.1 microgram/L (placebo), respectively (P < 0.05). In a subset of 6 obese men, in samples collected every 5 min, the GH response to both doses of L was significantly greater than that to 1 microgram/kg GHRH. To compare the response to low dose L in the obese and to determine the effects of feeding on this response, 0.2 mg/kg L was administered as described in part A to nonobese young men after an overnight fast (fasted) or a standardized breakfast (fed; part B). Low dose L was an effective GH secretagogue in nonobese young men; however, this effect was attenuated with feeding [43.6 +/- 7.9 (fasted) vs. 17.7 +/- 4.8 (fed) micrograms/L]. Of note, the response to low dose L in fasted obese individuals was similar to that in fed nonobese individuals. The administration of L was well tolerated in both groups. We conclude that L is an effective GH secretagogue in obese and nonobese young men and may have therapeutic benefits when administered to relative (obese or elderly) or absolute GH-deficient individuals.
Kirk
S E
SE
Department of Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Gertz
B J
BJ
Schneider
S H
SH
Hartman
M L
ML
Pezzoli
S S
SS
Wittreich
J M
JM
Krupa
D A
DA
Seibold
J R
JR
Thorner
M O
MO
D000328:Adult; D001552:Benzazepines / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004435:Eating; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D008297:Male; D009765:Obesity / Q000378:metabolism*; D012016:Reference Values; D013777:Tetrazoles / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*
D001552:Benzazepines; D013777:Tetrazoles; D019382:Human Growth Hormone; C081455:L 692429