Defective cold-induced stimulation of thyroxine 5′-deiodinase in brown adipose tissue of the genetically obese ( [formula omitted]) mouse

Abstract

Exposure of a normal lean mouse to cold (14°C) for 12 h increases the activity of thyroxine 5′-deiodinase in brown adipose tissue 26-fold. In contrast, exposure of the genetically obese, ob ob , mouse to cold results in little more than a doubling of thyroxine 5′-deiodinase activity. The physiological significance of endogenous 3,5,3′-triiodothyronine production in brown adipose tissue is not understood. However, it seems likely that defective cold-induced stimulation of the 5′-deiodinase in brown adipose tissue of the ob ob mouse might cause a relatively hypothyroid state of the tissue. Thyroid hormone is known to be required for a normal thermogenic response of brown adipose tissue to noradrenaline. It is suggested that the defect in the response of the 5′-deiodinase in the ob ob mouse could contribute to the defective thermogenic response of brown adipose tissue to cold-exposure and to noradrenaline.