Effect of Thyrotropin Injection on Pyridine Nucleotide Content of Thyroid in Normal and Hypophysectomized Rat

The oxidized and reduced forms of NAD and NADP were measured in the rat thyroid gland before and 3 hr after TSH was given intravenously to normal and hypophysectomized animals. In the normal rat, TSH increased the total NADP content and particularly the reduced form. Total NAD was unchanged 3 hr after TSH stimulation, and NADH was significantly increased. These data suggest that TSH either promoted new synthesis of pyridine nucleotides or inhibited their degradation, and also enhanced processes leading to reduction of pyridine nucleotides. Hypophysectomy had little effect on the concentration of pyridine nucleotides in the thyroid gland of the rat. TSH increased NADP with little change in NADPH, suggesting a lesser response to injected TSH of NADPH generating systems in the thyroid glands of hypophysectomized rats. (Endocrinology78: 1049, 1966)