Synergy of L-arginine and GHRP-2 stimulation of growth hormone in men and women: Modulation by exercise

Laurie Wideman, Judy Y. Weltman, James T. Patrie, Cyril Y. Bowers, Niki Shah, Shannon Story, Johannes D. Veldhuis, Arthur Weltman

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

We investigated the ability of exercise, a multipathway, potent, physiological stimulus for GH release, to alter the synergistic interaction of L-arginine (A) and GH-related peptide (GHRP)-2 (G) observed at rest and the ability of gender to further modulate this putative interaction. Subjects (9 men and 9 early follicular phase women) completed 30 min of constant load aerobic exercise in combination with intravenous infusions of saline (S), A (30 g over 30 min), G (1 μg/kg bolus), or both (AG) in separate study sessions in randomly assigned order. Measures of GH release were logarithmically transformed for statistical analysis. Similar to rest, exercise maintained the rank order (AG > G > A > S) of effective stimulation of GH release for the key response measures in men or women, a gender disparity in the time to reach the maximal serum GH concentration, the calculated endogenous GH half-life, and the observed effect of preinfusion (basal) serum GH concentrations on determining secretagogue responsiveness. Exercise potentiated the individual stimulatory actions of A and G, while blunting the relative magnitude of the synergistic (supra-additive) interaction observed at rest. We infer from the present data that 1) exercise is likely to induce release of both GHRH and somatostatin, 2) L-arginine may facilitate the effect of exercise by limiting somatostatin release, 3) GHRP-2 could further enhance the stimulatory impact of exercise by opposing central actions of somatostatin and/or heightening endogenous GHRH release, and 4) gender strongly controls the relative but not absolute magnitude of A/G synergy both at rest and after exercise.

Original languageEnglish (US)
Pages (from-to)R1467-R1477
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume279
Issue number4 48-4
DOIs
StatePublished - 2000

Keywords

  • Endocrine
  • Female
  • Male
  • Pituitary
  • Regulation
  • Somatotropin

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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