Relative effects of estrogen, age, and visceral fat on pulsatile growth hormone secretion in healthy women

Johannes D. Veldhuis, Susan B. Hudson, Dana Erickson, Joy N. Bailey, George Ann Reynolds, Cyril Y. Bowers

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Growth hormone (GH) secretion is subject to complex regulation. How pre- and postmenopausal age (PRE, POST), estradiol (E2) availability, and abdominal visceral fat (AVF) jointly affect peptidyl-secretagogue drive of GH secretion is not known. To this end, healthy PRE (n = 20) and POST (n = 22) women underwent a low- vs. high-E2 clamp before receiving a continuous intravenous infusion of GH-releasing hormone (GHRH) or GH-releasing peptide (GHRP-2). According to analysis of covariance, PRE and POST women achieved age-independent hypo- and euestrogenemia under respective low- and high-E2 clamps. All four of age (P < 0.001), E2 status (P = 0.006), secretagogue type (P < 0.001), and an age x peptide interaction (P = 0.014) controlled pulsatile GH secretion. Independently of E2 status, POST women had lower GH responses to both GHRH (P = 0.028) and GHRP-2 (P < 0.001) than PRE women. Independently of age, GHRP-2 was more stimulatory than GHRH during low E2 (P = 0.011) and high E2 (P < 0.001). Stepwise forward-selection multivariate analysis revealed that computerized tomographic estimates of AVF explained 22% of the variability in GHRH action (P = 0.002), whereas age and E2 together explained 60% of the variability in GHRP-2 drive (P < 0.001). These data establish that age, estrogen status, and AVF are triple covariates of continuous peptide-secretagogue drive of pulsatile GH secretion in women. Each factor must be controlled for to allow valid comparisons of GH-axis activity.

Original languageEnglish (US)
Pages (from-to)E367-E374
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume297
Issue number2
DOIs
StatePublished - Aug 1 2009

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Keywords

  • Estrogen
  • Growth hormone secretion
  • Growth hormone-releasing hormone
  • Growth hormone-releasing peptide
  • Human
  • Somatotropin

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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