Effect of thyroid-stimulating hormone on cultured thyrocytes obtained from patients with Graves' disease and...

Thyrocytes obtained from patients with Graves' disease were cultured for 3 days. This was followed by culture with 10 mU/mL thyroid stimulating hormone (TSH) (TSH group), TSH and sodium iodide (Nal group), or without (control group) for 3 additional days. On the 8th culture day, the amounts of intra- and extra-cellular cyclic adenosine monophosphate (cAMP), extracellular cAMP and thyroglobulin (TG), peroxidase (PO) activity, and cell numbers were measured. The amounts of intra- and extra-cellular cAMP correlated well. TSH increased the values of cAMP, TG and PO to levels higher than those of the control group. As the amount of Nal added to the medium increased, these values decreased. Addition of 10(-5) mol/L Nal lowered the value of cAMP only. When 10(-4) mol/L Nal was added, these three levels were lower than those of the TSH group and the value of cAMP was almost equal to that of the control group. On cell number, no difference was found between the cells cultured with TSH, TSH and Nal, and without TSH or Nal. When the thyrocytes were cultured with 1 mmol/L dibutyryl cAMP sodium salt or 8-bromoadenosine 3',5'-cyclic monophosphate instead of TSH, 10(-4) mol/L Nal did not lower the values of thyroglobulin and peroxidase activity. These results suggest that the Nal blocks the intracellular signal transduction provoked by TSH, only at the cAMP production level.