Effect of exercise training on the disappearance of cold adaptability in rats.
Following the transfer of cold-adapted rats to a warm environment at 25 degrees C, enhanced nonshivering thermogenesis and enlarged interscapular brown adipose tissue (BAT) decreased gradually and reached a steady state after 4 weeks of de-adaptation. Animals that were exercised in the process of de-adaptation, however, showed no decrease in enhanced nonshivering thermogenesis, but did show a decrease in BAT weight as compared with sedentarily de-adapted animals. Triiodothyronine (T3), the physiologically most active thyroid hormone, was at a higher plasma level in cold-adapted rats than in de-adapted animals with or without exercise loads. Although the resting level of T3 in running-trained rats was not higher than that in sedentary rats, some fluctuations of T3 level were observed during running.
D000222:Adaptation, Physiological; D002001:Adipose Tissue, Brown / Q000502:physiology; D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D009929:Organ Size; D010805:Physical Conditioning, Animal; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D013974:Thyroxine; D009638:Norepinephrine