Acute alterations in growth hormone-insulin-like growth factor axis in humans injected with endotoxin

Charles H. Lang, Valerie Pollard, Jie Fan, Lillian D. Traber, Daniel L. Traber, Robert A. Frost, Marie C. Gelato, Donald Prough

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Abstract

The purpose of the present study was to characterize the acute changes in the insulin-like growth factor (IGF) system in humans after administration of endotoxin (lipopolysaccharide; LPS). Escherichia coli LPS (4 ng/kg) was injected intravenously into healthy adults, and serial blood samples were collected for the next 5 h; subjects injected with saline served as time- matched controls. LPS administration resulted in a gradual decrease in the total extractable IGF-I concentration, which was reduced by ~20% over the final 2 h of the experiment; levels of free IGF-I were not significantly altered. LPS also produced a marked but transient elevation in growth hormone (GH) concentration. IGF-binding protein (BP)-1 levels were elevated more than fivefold 2 h after LPS injection, and thereafter levels gradually returned toward baseline. IGFBP-2 concentration also increased after LPS injection, but the maximal increase (~50% above basal) was observed during the final 2 h of the protocol. In contrast, IGFBP-3 levels did not vary over the period examined in response to LPS, and there was no apparent increase in number of BP-3 proteolytic fragments. Cortisol levels were increased early and remained two- to threefold above baseline throughout the protocol. No significant alterations in serum concentration of glucose or insulin were noted. LPS also produced an early elevation in tumor necrosis factor and a later increase in interleukin-6. These data indicate that the acute changes in the GH-IGF axis in humans in response to LPS are comparable with those observed in humans in other traumatic conditions and in animal models of endotoxemia and infection.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume273
Issue number1 42-1
StatePublished - Jul 1997
Externally publishedYes

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Keywords

  • Binding proteins
  • Cortisol
  • Glucose
  • Insulin
  • Interleukin-6
  • Lipopolysaccharide
  • Tumor necrosis factor

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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