Differential orderliness of the GH release process in castrate male and female rats

Evelien Gevers, Steve M. Pincus, Iain C.A.F. Robinson, Johannes D. Veldhuis

Research output: Contribution to journalArticle

61 Scopus citations

Abstract

Male- and female-specific modes of episodic growth hormone (GH) release are presumptively imposed by sex steroid hormones, and, although typically evident visually, are vividly distinguished quantitatively via a regularity statistic, approximate entropy (ApEn), in both the rat and human. GH secretory patterns may determine GH-stimulated growth and specific hepatic and muscle gene expression in the rat. Consequently, it is important to discern mechanisms that underlie their regulation. Here we have examined the impact of prepubertal gonadal suppression (at 4 wk of age) via surgical or pharmacological [gonadotropin-releasing hormone (GnRH) agonist] intervention on the regularity (ApEn) of GH release in male and female rats (at 10-11 wk of age) sampled at 10-min intervals for 10 h (n = 60 points) during a lights- out (dark) period. We observed a graded hierarchy of mean disorderliness of GH release that was quantifiable by ApEn measures, with maximal to minimal disorderliness in the following rank order: intact female, GnRH agonist- treated female, ovariectomized female, orchidectomized male, GnRH agonist- treated male, and intact male. These observations suggest a continuum of sex steroid actions on the regularity of GH secretion and, by inference, on the interplay among GH-releasing hormone, somatostatin, and GH/insulin-like growth factor I negative feedback.

Original languageEnglish (US)
Pages (from-to)R437-R444
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume274
Issue number2 43-2
DOIs
StatePublished - Feb 1998

Keywords

  • Entropy
  • Growth hormone
  • Pituitary
  • Rodent
  • Sex

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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