Age or factors associated with aging attenuate testosterone's concentration-dependent enhancement of the regularity of luteinizing hormone secretion in healthy men

Peter Y. Liu, Paul Y. Takahashi, Pamela D. Roebuck, Johannes D. Veldhuis

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Background: Healthy older men have reduced testosterone (Te) production and frequent, small irregular LH pulses. Which is cause and which is effect are not known. Rationale: In model systems, frequent and irregular LH pulses reflect attenuated feedback inhibition by Te. Hypothesis: Factors associated with aging impair negative feedback by Te. Subjects and Setting: Healthy men at an academic medical center were studied. Methods: The study used quantification of the regularity of LH release patterns during blockade of gonadal steroidogenesis and graded transdermal Te addback in 18 healthy men aged 18-65 yr. Results: In the cohort as a whole, stepwise Te repletion repressed LH concentrations (P = 0.001) and enhanced the quantifiable orderliness of LH release patterns (P < 0.001). By regression analysis, age attenuated the capability of increasing Te concentrations to regularize LH secretion patterns (P = 0.019). However, after a fixed GnRH stimulus, the effect of Te on LH regularity was invariant of the age factor (P = 0.16), thus pointing to a hypothalamic locus of impaired Te feedback. Summary: Aging disrupts the capability of systemic Te concentrations to maintain orderly LH secretion under endogenous, but not exogenous, GnRH drive. Conclusions: Age or factors associated with increased age reduce negative feedback by any given total Te concentration on hypothalamopituitary GnRH-LH outflow, thus contributing to disorderly LH secretion.

Original languageEnglish (US)
Pages (from-to)4077-4084
Number of pages8
JournalJournal of Clinical Endocrinology and Metabolism
Volume91
Issue number10
DOIs
StatePublished - Oct 2006

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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