Acute effect of physical exercise on serum insulin-like growth factor-binding protein 2 and 3 in healthy men: role of exercise-linked growth hormone secretion.
The purpose of this study was to delineate the role of GH on serum IGF-I, IGFBP-2 and -3 responses to exercise. Hormones were evaluated in six trained male subjects before (-30, -15, 0), during (+15) and after (+30, +45, + 60, +90 min) a thirty-minutes treadmill exercise (60% VO2max), both after a single administration of a somatostatin analog (i.e., octreotide, 0.1 mg sc) and after saline. The same evaluations were performed without exercise with similar treatments. The results showed that: 1) octreotide significantly inhibited the GH response to exercise, 2) exercise increased IGFBP-3 concentration (+37.4% at +90, p < 0.05), whereas no modification of IGFBP-2 and of IGF-I/ IGFBP-2 and IGFBP-3/IGFBP-2 ratios were observed, 3) octreotide amplified the IGFBP-3 increase after exercise (p < 0.01 vs. exercise, from + 30 to + 60, or octreotide alone) and, without exercise, slightly increased IGFBP-3 (+15% at +75, p < 0.05) and decreased IGF-I (-14.8% at +75, p < 0.01). We concluded that GH has a reduced role, as a stimulating factor, in the serum acute IGFBP-3 increase after exercise and that octreotide is probably able to directly amplify this response. Unfortunately, we can only speculate on the physiological pathways involved.
Di Luigi
L
L
Endocrinology Unit, University Institute of Motor Sciences, Rome, Italy. iusm.endocrinol@uni.net
Guidetti
L
L
Nordio
M
M
Baldari
C
C
Romanelli
F
F
D000818:Animals; D015444:Exercise / Q000502:physiology*; D013006:Growth Hormone / Q000378:metabolism* / Q000494:pharmacology; D006728:Hormones / Q000008:administration & dosage; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D008297:Male; D015282:Octreotide / Q000008:administration & dosage; D013997:Time Factors
D006728:Hormones; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D013006:Growth Hormone; D015282:Octreotide