SOME EFFECTS OF THYROTROPIC HORMONE ON THE REPRODUCTIVE SYSTEM OF NORMAL, THYROIDECTOMIZED OR ADRENALECTOMIZED FEMALE RATS

ARELATIONSHIP BETWEEN the hyperthyroid state and the female reproductive system is fairly well established. Hyperthyroidism, produced by injection of thyroxin or feeding desiccated thyroid, may cause anestrus, pseudopregnancy, resorption or prolonged gestation in the rat (1, 2, 3). The effect of thyrotropic hormone on the reproductive system of the rat has not been extensively investigated because rats have been shown to be relatively unresponsive to this hormone. Sufficiently large dosage, however, will increase metabolism and produce other indications of hyperthyroidism (4). The guinea pig, on the other hand, is very sensitive to thyrotropic hormone, showing not only stimulation of the thyroid but also luteinisation of the ovaries (5, 6, 7). The following experiments were undertaken to determine: a) whether the ovaries of immature and mature rats would become luteinised after injections of thyrotropic hormone; and if so, whether the luteinization was due to a hyperthyroid condition or to gonadotropic substances in the thyrotropic preparation; and b) whether such luteinized ovaries would help prolong the survival time of adrenalectomised rats1 or prepare the uterus for the production of traumatic placentomata.