[Role of thyroid hormone in cold adaptation. 2. Increase of food consumption and fecal excretion of thyroxine during cold exposure (author's transl)].
In order to clarify the relationship between food consumption and excretion of thyroxine during cold exposure, 131I-thyroxine was injected to 1w- and 3w-cold exposed rats and the radioactivity of 131I in the feces and urine was counted over the first 24 hr and the next same period of time following the injection. The percentage of a dose of radioactive thyroxine excreted into the feces over the first 24 hr was the highest in 1w-cold exposed rats, whereas in 3w-cold exposed rats the excretion of radioactive thyroxine did not differ from the values in warm adapted rats. Since the correlation curve between fecal excretion of thyroxine and fecal weight was linearly positive and food consumption increased during the early stage of cold exposure, larger fecal thyroxine observed in the first week after cold exposure was inferred to be result from increased food consumption as well as fecal volume in this period. Nevertheless, since the increment of fecal excretion of thyroxine in 1w-cold exposed rats was only 30% as compared with the value of control group, it is impossible to explain 2-3 fold increase in thyroxine requirement during early stage of cold exposure by the increase in fecal excretion of thyroxine.
D000064:Acclimatization; D000818:Animals; D001835:Body Weight; D003080:Cold Temperature; D005243:Feces / Q000032:analysis; D005247:Feeding Behavior; D008297:Male; D051381:Rats; D013974:Thyroxine / Q000378:metabolism* / Q000652:urine; D013997:Time Factors
D013974:Thyroxine