Thyroid hormone secretion rates and food consumption of the hamster ( Mesocricetus auratus) at 25.5° and 4.5°C

Abstract

The thyroid hormone secretion rates (TSR) were determined on the mature, female hamster ( Mesocricetus auratus) at 25.5 and 4.5°C. A rapid increase in thyroid activity was observed within the first 10 days of cold exposure. Thyroid activity increased up to 39–40 days, then plateaued for a period up to 65–70 days, and finally declined toward the pre-exposure levels by 150 days at 4.5°C. Food consumption determined at 25.5°C increased very rapidly after exposure of the hamsters to 4.5°C. Increases to twice the control values were recorded at 12–13 days after cold exposure. Food consumption then declined to about 60% above the pre-exposure level and plateaued rather irregularly up to 55 days of exposure. It appears that both increased thyroid activity and increased food consumption may help to acclimate the hamster to cold. Although food consumption remains high up to 55 days of cold exposure, it appears that by 150 days of cold exposure, thyroid hormone secretion rates have declined to almost pre-exposure levels.