期刊
JOURNAL OF APPLIED PHYSIOLOGY
卷 100, 期 1, 页码 120-128出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.01415.2004
关键词
hormone pulsatility; insulin-like growth factor-I; soldiers; leptin; testosterone
The pulsatile release of growth hormone (GH) and luteinizing hormone (LH) from the anterior pituitary gland is integral for signaling secretion of insulin-like growth factor (IGF)-I and testosterone, respectively. This study examined the hypothesis that 84 h of sustained physical exertion with caloric and sleep restriction alters the secretion of GH and LH. Ten male soldiers [22 yr (SD 3), 183 cm (SD 7), 87 kg (SD 8)] had blood drawn overnight from 1800 to 0600 every 20 min for GH, LH, and leptin and every 2 h for IGF-I ( total and free), IGF binding proteins-1 and - 3, testosterone (total and free), glucose, and free fatty acids during a control week and after 84 h of military operational stress. Time-series cluster and deconvolution analyses assessed the secretion parameters of GH and LH. Significant results (P <= 0.05) were as follows: body mass (-3%), fat-free mass (-2.3%), and fat mass (-7.3%) declined after military operational stress. GH and LH secretion burst amplitude (similar to 50%) and overnight pulsatile secretion (similar to 50%), IGF binding protein-1 (+67%), and free fatty acids (+33%) increased, whereas leptin (-47%), total (-27%) and free IGF-I (-32%), total (-24%) and free testosterone (-30%), and IGF binding protein-3 (-6%) decreased. GH and LH pulse number were unaffected. Because GH and LH positively regulate IGF-I and testosterone, these data imply that the physiological strain induced a certain degree of peripheral resistance. During periods of energy deficiency, amplitude modulation of GH and LH pulses may precede alterations in pulse numbers.
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