Androgens Do Not Regulate the Growth Hormone Response to GHRH in Elderly Men

Gp, Ceda; Ceresini, Graziano; Denti, Licia; Cortellini, P; Ar, Hoffman; Valenti, Giorgio

doi:10.1055/s-2007-1009325

Cited by 10 publications

(2 citation statements)

References 8 publications

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“…In contrast, at the hypothalamic-pituitary axis, stimulation of GH release with GHreleasing peptide in the presence of estrogens enhances GH secretory response in postmenopausal women (2). Significant positive correlations between serum T levels and spontaneous GH secretion (74) and GHRH-stimulated GH release have been reported in some (16), but not other (12), studies of older andropausal men. In a cross-sectional survey of healthy aging men, we recently reported (7) that age was a strong, independent predictor of serum IGF-I and IGFBP-3 levels and that levels of total T were related to IGF-I independently of age.…”

Section: Discussionmentioning

confidence: 99%

Effects of GH and/or sex steroids on circulating IGF-I and IGFBPs in healthy, aged women and men

Münzer¹,

Rosen²,

Harman³

et al. 2006

American Journal of Physiology-Endocrinology and Metabolism

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. Effects of GH and/or sex steroids on circulating IGF-I and IGFBPs in healthy, aged women and men. Am J Physiol Endocrinol Metab 290: E1006 -E1013, 2006. First published January 3, 2006 doi:10.1152/ajpendo.00166.2005.-Circulating GH, IGF-I, IGFBP-3, and sex steroid concentrations decrease with age. GH or sex steroid treatment increases IGFBP-3, but little is known regarding the effects of these hormones on other IGFBPs. We assessed the effects of 26 wk of administration of GH, sex steroids, or GH ϩ sex steroids on AM levels of IGF-I, IGFBPs 1-5, insulin, glucose, and osteocalcin and 2-h urinary excretion of deoxypyridinolline (DPD) cross-links in 53 women and 71 men aged 65-88 yr. Before treatment, in women and men, IGF-I was directly related to IGFBP-3 (P Ͻ 0.001 and P Ͻ 0.0001) and IGFBP-1 to IGFBP-2 (P ϭ 0.0001). In women, IGFBP-1 was inversely related to insulin (P Ͻ 0.0005) and glucose (P Ͻ 0.005) and IGFBP-4 to osteocalcin (P Ͻ 0.01). IGFBP-4 and IGFBP-5 were not significantly related to DPD cross-links. GH and/or sex steroid increased IGF-I levels in both sexes, with higher concentrations in men (P Ͻ 0.001). In women, the IGF-I increment after GH was attenuated by hormone replacement therapy (HRT) coadministration (P Ͻ 0.05). Hormone administration also increased IGFBP-3. IGFBP-1 was unaffected by GH ϩ sex steroids, whereas GH decreased IGFBP-2 by 15% in men (P Ͻ 0.05). Hormone administration did not change IGFBP-4, whereas in men IGFBP-5 increased by 20% after GH (P Ͻ 0.05) and 56% after GH ϩ testosterone (P ϭ 0.0003). These data demonstrate sexually dimorphic IGFBP responses to GH. Additonally, HRT attenuated or prevented GH-mediated increases in IGF-I and IGFBP-3. Whether GH and/or sex steroid administration alters local tissue production of IGFBPs and whether the latter influence autocrine or paracrine actions of IGF-I remain to be determined. growth hormone; insulin-like growth factor-binding protein INSULIN-LIKE GROWTH FACTOR-BINDING PROTEINS (IGFBPs) are members of a structurally and genetically related superfamily of proteins that bind to insulin-like growth factors (IGFs) with high, but variable, affinities (34). In addition to their principal roles as modulators of endocrine, paracrine, and autocrine actions of IGFs, IGFBPs exert growth hormone (GH)-independent effects on various tissues in vivo and in vitro (38, 59). The detailed mechanisms of IGFBP synthesis and their metabolic activities remain incompletely understood. However, it has been reported (6, 64, 65) that circulating levels of IGFBP-1 are regulated by insulin and IGF-I. IGFBP-2 is also related to insulin levels (13), whereas increases in IGFBP-3 are closely correlated with those in IGF-I in response to GH in children (47) and adults (39) with GH deficiency (GHD). IGFBP-4 and -5 inhibit and stimulate, respectively, IGF-mediated effects on bone (53). How these important modulatory proteins are affected by aging and age-related changes in endocrine balance and the extent to which hormone replacement reverses such changes is incomplet...

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Section: Discussionmentioning

confidence: 99%

Effects of GH and/or sex steroids on circulating IGF-I and IGFBPs in healthy, aged women and men

Münzer¹,

Rosen²,

Harman³

et al. 2006

American Journal of Physiology-Endocrinology and Metabolism

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“…Some investigators have reported that there is no correlation between serum testosterone levels and GH secretion (Lang et al, 1987;Ceda et al, 1989). However, androgens appear to stimulate GH secretion in hypogonadotrophic men (Liu et al, 1987).…”

Section: Role Of Sex Steroidsmentioning

confidence: 99%

Growth hormone therapy in elderly people: an age‐delaying drug?

Bouillanne

Rainfray

Tissandier

et al. 1996

Fundamemntal Clinical Pharma

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The aims of this review are to present a brief overview of growth hormone (GH) physiology and to summarize the studies of GH treatment in adults. Special attention has been paid to randomized controlled trials. Studies have revealed a partial deficiency of GH secretion in the elderly. GH secretion on the average declines by 14% with each decade in normal adults after 20 years of age. Aging has a central effect on the GH secretion and peripheric effect on insulin-like growth factor 1 (IGF-1) through changes in the body composition. GH administration may attenuate several important decrements in body composition and in function associated with aging. GH may also have very potent anabolic effects in surgical situations. Short-term side-effects of GH therapy include edema, carpal tunnel syndrome and arthralgia. A number of agents such as oral GH-releasing peptides (GHRPs) increase GH secretion; they may be an alternative to GH treatment in the future. Further studies of GH replacement are needed, examining issues such as dosage, tolerance and efficacy before the widespread use of GH in the elderly is advocated.

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