Evaluation of pulsatile patterns of growth hormone release in humans: A brief review

Hartman, Mark L.; Iranmanesh, Ali; Thorner, Michael O.; Veldhuis, Johannes D.

doi:10.1002/ajhb.1310050603

Cited by 50 publications

(16 citation statements)

References 49 publications

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“…Exogenous factors, such as photic conditions, also affect the secretion of GH. Spontaneous GH secretion shows a distinct increase during the night in humans (Finkelstein et al 1972;Hartman et al 1993), monkeys (Kaler et al 1986) and rats (Davies et al 2004). In ruminants, it was reported that GH was secreted with an ultradian rhythm with higher peaks in the daytime than nighttime in male calves (Hänninen et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Effects of photoperiod on the secretion of growth hormone in female goats

Jin

Yaegashi

Sawai

et al. 2012

Animal Science Journal

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The aim of the present study was to clarify the effect of photoperiod on the secretion of growth hormone (GH) in goats. Adult female goats were kept at 20°C with an 8-h or 16-h photoperiod, and secretory patterns of GH for 4 h (12.00 to 16.00 hours) were compared. In addition, the goats were kept under a 16-h photoperiod and orally administered saline (controls) or melatonin, and the effects of melatonin on the secretion of GH were examined. GH was secreted in a pulsatile manner. There were no significant differences in pulse frequency between the 8- and 16-h photoperiods; however, GH pulse amplitude tended to be greater in the group with the 16-h photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the 16-h photoperiod (P < 0.05). The GH-releasing response to GH-releasing hormone (GHRH) was also significantly greater for the 16-h photoperiod (P < 0.05). There were no significant differences in GH pulse frequency between the saline- and melatonin-treated groups. However, GH pulse amplitude and mean GH concentrations were significantly greater in the saline-treated group (P < 0.05). The present results show that a long photoperiod enhances the secretion of GH, and melatonin modifies GH secretion in female goats.

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Section: Introductionmentioning

confidence: 99%

“…Spontaneous GH secretion shows a distinct increase during the night in humans (Finkelstein et al . 1972; Hartman et al . 1993), monkeys (Kaler et al .…”

Section: Introductionmentioning

confidence: 99%

Effects of photoperiod on the secretion of growth hormone in female goats

Jin

Yaegashi

Sawai

et al. 2012

Animal Science Journal

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“…Although prohibited in sports there is not yet an approved method to detect hGH abuse. The simple quantification of hGH in serum is not capable to detect growth hormone abuse as hGH is secreted in a pulsatile manner [1].…”

Section: Introductionmentioning

confidence: 99%

Potential parameters for the detection of hGH doping

Kniess¹,

Ziegler²,

Kratzsch

et al. 2003

Analytical and Bioanalytical Chemistry

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The aim of our hGH application study with non-competitive athletes was the investigation of selected serum parameters from different processes affected by hGH. Fifteen athletes (age 21-33, mean 24) were treated with 0.06 IU hGH/kg BW per day or placebo (10 hGH, 5 placebo) respectively for 14 days. Blood samples were taken prior to, during and until 10 weeks after treatment. The concentrations of the following markers were determined in relevant serum samples: IGF-I, IGFBP-3, ALS, PIIINP, PINP, osteocalcin, and leptin. The IGF-I concentration increased rapidly within the hGH treatment group and showed significantly higher levels compared to baseline even 3 days after application. The response of the IGFBP-3 to the hGH applications was lower in comparison to IGF-I. The hGH group showed an increasing IGFBP-3 compared to baseline from day 4 till day 15. The response of PIIINP to hGH is clearly delayed compared to the IGF-I axis, but the PIIINP concentration remains on an increased level for a longer period (from day 4 until day 21). The time course and the extent of response varied strongly interindividually. PINP and osteocalcin showed only a small response to hGH applications. These parameters are characterised by a strong scattering of base values compared with the small response. In the hGH treatment group very different leptin concentrations were found at the beginning of the study, but after treatment decreasing leptin levels were observed in all cases. The determination of only one parameter will not be sufficient for detection of hGH abuse. A combination of markers by mathematical methods can be helpful to distinguish between placebo and hGH-treated athletes. By using the suggested discriminant function the data sets of hGH and placebo-treated athletes could be separated without false positive results.

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“…In addition to the rat, sexually dimorphic GH profiles have been reported in turkeys, sheep, horses, mice, chickens (cf. Shapiro et al, 1995), and humans (Hartman et al, 1993;Van den Berg et al, 1996;Engstrom et al, 1998). In humans, numerous reports, generally using GH-deficient individuals, have shown that GH replacement can restore drug-metabolizing enzymes to normal levels (Redmond et al, 1980;Cheung et al, 1996).…”

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confidence: 99%

Sexually Dimorphic Regulation of Hepatic Isoforms of Human Cytochrome P450 by Growth Hormone

Dhir¹,

Dworakowski²,

Thangavel³

et al. 2005

J Pharmacol Exp Ther

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Sex differences in drug metabolism have been reported in numerous species, including humans. In rats and mice, sexdependent differences in circulating growth hormone profiles are responsible for the differential expression of multiple sexdependent isoforms of cytochrome P450, which is the basis for the sexual dimorphism in drug metabolism. In contrast, very little is known about sex differences in human isoforms of cytochrome P450 and their regulation by growth hormone. In this study, we have examined the effects of physiologic-like exposure doses to dexamethasone and/or pulsatile (masculine) or constant (feminine) human growth hormone on expression levels of CYP3A4, 1A2, 2D6, and 2E1 and the glucocorticoid and growth hormone receptors in hepatocyte cultures obtained from men and women donors. We report that growth hormone can regulate expression of CYP3A4, 1A2, and 2D6. The masculine-like pulsatile growth hormone profile suppresses dexamethasone-induced CYP3A4, 1A2, and 2D6, whereas the feminine-like constant profile is permissive allowing isoform expression to be equal to or greater than glucocorticoid induction alone. There are intrinsic sexual differences in hepatocytes of men and women resulting in different levels of responsiveness of CYP3A4, 1A2, and hormone receptor expression to the same sexually dimorphic growth hormone profiles. Last, although real, the sexually dimorphic effects of growth hormone on human cytochrome P450 expression are not as dramatic as those observed in rats and could easily be overlooked by the heterogeneous backgrounds of human populations.

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Evaluation of pulsatile patterns of growth hormone release in humans: A brief review

Cited by 50 publications

References 49 publications

Effects of photoperiod on the secretion of growth hormone in female goats

Effects of photoperiod on the secretion of growth hormone in female goats

Potential parameters for the detection of hGH doping

Sexually Dimorphic Regulation of Hepatic Isoforms of Human Cytochrome P450 by Growth Hormone

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