THYROTROPHIC HORMONE CONTENT OF THE BLOOD SERA AND PITUITARY GLANDS OF THIOUREA-, SULFADIAZINE-TREATED AND THYROIDECTOMIZED RATS1

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Abstract
The feeding of thiourea or sulfadiazine to rats for 14 or 45 days causes a diminution in the quantity of thyroid-stimulating factor in the blood sera and pituitary glands as judged by the effects of such materials on the rate of metamorphosis of Rana pipiens larvae. Rats thyroidectomized for 6 mos. possess increased amts. of thyrotrophic hormone in blood sera and hypophyses. Rats fed thiourea for 20 days and then thyroidectomized possess increased quantities of thyrotrophin in their blood 48 hrs. after the operation; the conc. of this hormone in the pituitary glands of such animals is below that found in the glands of rats fed a normal diet and thyroidectomized for the same period of time. The results are best interpreted on the basis that thiourea and sulfadiazine, by depressing the formation of active thyroid principle, cause an increased release of thyrotrophin from the pituitary into the blood where, however, it appears in reduced amt. because of its removal and increased utilization by the enlarging thyroid gland.