Effects of growth hormone administration on luteinizing hormone secretion in healthy older men and women

Ranganath Muniyappa, Shannon D. Sullivan, Sri Harsha Tella, Brent S. Abel, S. Mitchell Harman, Marc R. Blackman

Research output: Contribution to journalArticle

Abstract

The known interactions between the somatotropic and hypothalamic-pitui-tary-gonadal (HPG) axes have not been well delineated in older individuals. Aging-associated decline in insulin like growth factor-1 (IGF-1) levels has been proposed to play a role in reproductive senescence in animals. However, the effects of GH on LH secretion are unknown in older individuals. Our objective was to determine whether GH modulates LH secretion or levels of sex steroids (SS) in healthy older (ages 65–88 years) men (n = 24) and women (n = 24) with low-normal plasma IGF-1 levels. In a double-masked, placebo-controlled (n = 24), randomized study, we evaluated the effects of GH (n = 24, 20 μg/kg sc 3×/week) for 26 weeks on nocturnal LH secretory dynamics [(8PM to 8AM, Q20) min sampling and analyzed by multiparameter deconvolution algorithm]. Indices of LH secretion [frequency, mass per burst, pulsatile production rate, and approximate entropy (ApEn)] and fasting serum IGF-1, SHBG, and SS (TT, fT, or E2) were measured. At baseline, all indices of LH secretion (frequency, mass per burst, pulsatile production rate) were inversely (P < 0.05) related to IGF-1, but not to mean nocturnal serum GH concentrations. GH administration for 26 weeks increased serum IGF-1, but exerted no significant effects on LH secretory dynamics, or concentrations of SSs (TT, fT, or E2) or SHBG in older women or men. These data suggest that GH-mediated increases in IGF-1 do not modulate the HPG axis in older individuals.

Original languageEnglish (US)
Article numbere13516
JournalPhysiological Reports
Volume5
Issue number23
DOIs
Publication statusPublished - Dec 1 2017

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Keywords

  • Aging
  • Growth hormone
  • Luteinizing hormone
  • Pulsatility

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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