Relationship between changes in body composition and insulin responsiveness in models of the aging rat

N. Barzilai, L. Rossetti

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Abstract

Increased body weight (BW) is one of several confounding factors that may contribute to the development of insulin resistance in human aging. Therefore aging-associated increase in BW was determined by 3H2O in Sprague-Dawley (S-D, n = 40) rats and was highly correlated with increased lean body mass (LBM), fat mass (FM), and plasma insulin and free fatty acid (FFA) levels (r2 > 0.850, P < 0.01 for all). Insulin (18 mU · kg-1 · min-1) responsiveness (R(d); 270 ± 10 μmol · kg LBM-1 · min-1, P < 0.01) decreased by 17% between 2 and 4 mo but did not decline further at 14 mo. This decrease was inversely correlated with the increase in FM between 2 and 4 mo (r2 = 0.522, P < 0.05). The decline in R(d) was accompanied by an ~20% decrease in glycolytic rate by 4 mo (P < 0.01) and in glycogen synthesis rate at 14 mo (P < 0.01) compared with 2-mo rats. Thus early impairment in intracellular glucose metabolism occurred concomitantly with an initial, rapid, and disproportionate increase in FM compared with LBM. Further increases in FM after 4 mo of age were not associated with a further decrease in insulin responsiveness in either S-D or Fischer 344 aging rats.

Original languageEnglish (US)
Pages (from-to)E591-E597
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume269
Issue number3 32-3
StatePublished - Jan 1 1995

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Keywords

  • aging
  • fat mass
  • glycogen synthesis
  • glycolysis
  • lean body mass

ASJC Scopus subject areas

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

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