The importance of the adrenergic beta-receptors for thermogenesis and survival of acutely cold-exposed mice

Abstract

In normal warm-adapted mice a lowering of the ambient temperature to 0 °C was followed by piloerection, shivering, and an increase of oxygen consumption, which prevented a serious hypothermia. The survival rate after 4 h cold exposure was 82%. Mice pretreated with a β-receptor blocking agent, propranolol, MJ 1999, or INPEA, showed piloerection and shivering when exposed to 0 °C, but their ability to increase heat production was impaired. Depending upon the dose of the β-receptor blocking agent used, the increase in the metabolic rate was diminished, and rectal temperature and survival rate dropped sharply. After 25 μg/g MJ 1999, only 13% of the animals survived. After 20 μg/g propranolol or 100 μg/g INPEA all animals died. The results give evidence for the importance of the sympatho–adrenal system in general for the maintenance of body temperature and the survival after acute cold exposure, and for the special importance of the adrenergic β-receptors, which are necessary for the animals to increase their heat production.