Effect of temperature and hydration on thyroid function in Albino rats

ABSTRACT

The effect of some environmental factors namely temperature and hydration on thyroid activity was studied in an experimental model using albino rat. The parameters used for the assessment of such an activity were protein bound iodine [PBI], free thyroxine [T[4]] and total cholesterol in serum. The levels of PBI and T[4] in serum were higher in winter than in summer and this demonstrates clearly the role of the thethyroid gland in calorigenesia. PBI and T[4] levels were also higher with hydration. Cholesterol levels were higher in summer than in winter and on dehydration than hydration. The increase in T[4] was accompanied by a decrease in cholesterol levels in serum and vice versa. T[4] seems to play a role in sterol removal from blood. This investigation demonstrates the importance of environmental factors in evaluating thyroid activity and the present data may be useful as a standard for further studies on this animal