Effects of heat exposure on adrenergic modulation of insulin and glucagon secretion in sheep

Fumiaki Itoh, Koicrn Hodate, Shinichiro Koyama, Michael T. Rose, Mitsuto Matsumoto, Akihito Ozawa, Yoshiaki Obara

Research output: Contribution to journalArticlepeer-review

8 Citations (SciVal)

Abstract

The effects of heat exposure on the adrenergic modulation of pancreatic secretion were investigated. Five ewes fed at maintenance level (ME base) were housed in thermoneutral (TN; 20°C) and hot (30°C) environments. Heat exposure caused an increase in respiration rate and a slightly higher rectal temperature, and decreases in basal insulin and glucose concentrations. Infusions of saline plus epinephrine caused increases in glucagon and glucose concentrations, and no significant change in insulin secretion. Phentolamine (an adrenergic α-antagonist) plus epinephrine augmented insulin secretion; however, this insulin secretory response was inhibited by heat exposure. Propranolol (a β-antagonist) plus epinephrine produced a slight decrease in insulin secretion in the TN environment, whereas no effect was observed during heat exposure. While glucagon secretion through α-adrenergic stimulation was not affected by heat exposure, homeostatic signals controlling insulin release seemed to be affected during heat exposure. We thus hypothesised that insulin concentration is decreased in sheep fed at maintenance level in hot environments, and that this response is mediated in part by a modulation of β-adrenergic function.

Original languageEnglish
Pages (from-to)193-198
Number of pages6
JournalEndocrine Journal
Volume48
Issue number2
DOIs
Publication statusPublished - 2001

Keywords

  • Adrenergic modulation
  • Glucagon
  • Heat exposure
  • Insulin
  • Sheep

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