Metabolic and Maturational Effects of Thyroxine on the Infant Rat

Abstract
The effect of alterations in thyroid status upon O2 consumption and development was studied in rats of different ages. Thyroidectomy or thyroxine administration did not influence metabolic rate or body temperature during the first 2 wks. of life, when the rat is essentially poikilothermic. During this period thyroxine increased brain cholesterol and locomotor activity and advanced the time of eye-opening.