Effects of throxine on calorigenic response of the newborn rat to norepinephrine
Steele, R.E.; Wekstein, D.R.
American Journal of Physiology 224(4): 979-984
1973
ISSN/ISBN: 0002-9513 PMID: 4698815 Document Number: 60789
Preweanling rats with different amounts of circulating thyroid hormone were given by subcutaneous injection 300 mu g/kg noradrenaline, and their change in oxygen consumption was measured. Thyroid hormone-deficient rats were born and nursed by mothers given 0.2% propylthiouracil (PTU) in the diet. Thyroxine-treated rats were born and nursed by PTU-fed mothers which had been given by injection daily 25 mu g of L-thyroxine since the 11th day of gestation. These young received daily injections of 1 to 3 mu g L-thyroxine. Control rats were born and nursed by mothers given a control diet. The heat production response of the thyroid hormone-deficient rats to noradrenaline was considerably less than that of the thyroxine-treated rats and differed only from the controls at 21 days of age. It is concluded that thyroid hormone is essential for the full mainifestation of the increased heat production elicited in the preweanling rat in response to noradrenaline.