Effect of human chorionic gonadotropin on human thyroid tissue in vitro.

Thyroid stimulating substances other than TSH have been found in certain disease states associated with hyperthyroidism. The thyroid stimulator associated with the thyrotoxicosis of trophoblastic disease is uncertain; however, recent evidence suggests a role for hCG. To explore the thyroid stimulating properties of hCG further, we examined the ability of hCG to displace [1252]TSH from receptors on human thyroid membrane and to generate cyclic-AMP (c-AMP) from human thyroid slices. Human chorionic gonadotropin at a concentration of 40 IU/ml displaced labeled TSH from human thyroid membranes and, at a concentration of 69 IU/ml, hCG caused the generation of c-AMP in thyroid slices. These results suggest that hCG can bind to the TSH receptor on thyroid cells and can stimulate them to produce c-AMP at concentrations of hCG within the range that is found in trophoblastic disease.