Forty-five male, weanling Sprague-Dawley rats were matched by weight into three groups
(n = 15). One group was fed ad libitum a semipurified diet containing all essential nutrients and 30 ppm of zinc (control).
A second group was fed ad libitum a similar diet but with a deficient zinc intake of < 1 ppm (ZnD). A third group was
pair-fed PF) the control diet in amounts equal to that consumed by the matched ZnD
animals. After 42 days, the animals were fasted for 12 hr then five animals from each
group were sacrificed and the remainder was exposed to 3°C for 6 hr. Rectal temperatures
were lower (p < 0.05) in ZnD at 23°C and during cold exposure. Plasma thyroxine (T4) and triiodothyronine (T3) concentrations were reduced (p < 0.05) at room temperature in ZnD rats. During cold
exposure, the ZnD animals had depressed (p < 0.05) plasma thyrotropin, T4 and T3 concentrations. Thus, ZnD adversely affects thermoregulatory performance of rats
acutely exposed to cold by influencing thyroid hormone metabolism.
Zinc - Thyroid Hormones - Temperature Regulation - Cold
