Dose-response study of GH effects on circulating IGF-I and IGFBP-3 levels in healthy young men and women.
The aim of our study was to define the dose-response effect of a short-term treatment with different recombinant human growth hormone (rhGH) doses (1.25, 2.5, 5.0, 10.0, and 20.0 micrograms . kg-1. day-1 for 4 days) on insulin-like growth factor I (IGF-I) and insulin-like growth factor-binding protein (IGFBP)-3 levels in 21 normal young adults of both sexes. The dose of 1.25 microgram/kg rhGH did not modify IGF-I levels. The dose of 2.5 micrograms/kg rhGH significantly increased IGF-I levels in men (P < 0.05) but not in women, whereas the higher doses increased IGF-I levels in both sexes (P < 0.002). IGFBP-3 levels were not modified by 1.25 or 2.5 micrograms/kg rhGH in either sex. On the other hand, 5.0 micrograms/kg increased IGFBP-3 levels in men (P < 0.05) but not in women, whereas the higher doses increased IGFBP-3 levels similarly in both sexes (P < 0.02). In conclusion, our results demonstrate that IGF-I and IGFBP-3 responses to rhGH are dose and sex dependent. However, IGFBP-3 is less sensitive than IGF-I to rhGH stimulation.
Ghigo
E
E
Division of Endocrinology, Department of Internal Medicine, University of Turin, 10126 Torino, Italy.
Aimaretti
G
G
Maccario
M
M
Fanciulli
G
G
Arvat
E
E
Minuto
F
F
Giordano
G
G
Delitala
G
G
Camanni
F
F
D000328:Adult; D004305:Dose-Response Relationship, Drug; D005260:Female; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D011994:Recombinant Proteins; D012016:Reference Values; D012727:Sex Characteristics
D018972:Insulin-Like Growth Factor Binding Protein 3; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I