Glucoregulatory and metabolic responses to heat exposure in rats

R. Chayoth, A. F. Nakhooda, P. Poussier, E. B. Marliss

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


To determine the possible role of altered secretion and effects of insulin in fuel homeostasis during heat exposure, the hormonal and metabolic milieu of three groups of rats were studied. The first was placed at 35°C for 12 days (HE), the second was pair-fed (PF) to the first but maintained at 23°C, and the third was allowed to eat ad libitum at 23°C (C). Plasma insulin, glucagon, glucose, and free fatty acids (FFA), and blood lactate, pyruvate, 3-hydroxybutyrate, and individual amino acids were determined. To further characterize glucoregulation, an intraperitoneal glucose tolerance test (1 mg/g body wt) and isotopic glucose turnover (primed infusion of [3-3H]glucose) were performed. In HE rats, weight was constant for the last third of the period, and metabolic state 4 h after food removal was characterized by euglycemia but hypoinsulinemia, elevated blood pyruvate and FFA, and normal 3-hydroxybutyrate compared with C. Lowered levels of branched-chain amino acids and arginine were found. Fourteen hours after food removal glucose turnover was decreased. However, glucose intolerance accompanied by hyperinsulinemia was also found. Many of these changes were also seen in PF, including constant weight, fasting euglycemia, hypoinsulinemia, elevated FFA, and lowered valine and isoleucine. In contrast, pyruvate concentrations were normal, that of 3-hydroxybutyrate was elevated, and the decrement in glucose turnover was smaller than in HE rats. The glucose tolerance was similar to that of HE but accompanied by hypoinsulinemia. The results in HE suggest decreased energy metabolism, insulin secretion altered in a complex manner, and altered insulin action. The differences between HE and PF rats indicate that only some of the effects are due to food intake restriction.

Original languageEnglish
Pages (from-to)E465-E470
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number6
StatePublished - 1 Jan 1984
Externally publishedYes

ASJC Scopus subject areas

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


Dive into the research topics of 'Glucoregulatory and metabolic responses to heat exposure in rats'. Together they form a unique fingerprint.

Cite this