Histochemical and biochemical study on adenylate cyclase and 5'-nucleotidase activity in thyroid glands with normal...

The adenylate cyclase and 5'-nucleotidase activity was measured biochemically in the thyroid glands from patients with various thyroid diseases in comparison with normal thyroid. The basal adenylate cyclase activity in normal thyroid was 159.3 p-moles cAMP/min./g tissue. The activity was elevated to 230% of basal with 20 mM NaF and 190% of basal with 100 mU/ml TSH. These values in chronic thyroiditis and Graves' disease were not significantly different from the values of normal thyroid. In adenomatous goiter, adenoma and carcinoma, the basal adenylate cyclase activity was significantly higher than that of normal thyroid. Parallel to the biochemical determination of both enzyme activities, the distribution of histochemically demonstrable adenylate cyclase and 5'-nucleotidase activity was described in the follicular cells with normal and various thyroid diseases. The reaction product of adenylate cyclase and 5'-nucleotidase activity was restricted to the plasma membrane of the follicular cells. However, the distribution and intensity of the adenylate cyclase reaction varied in each thyroid disease, except for the absence of reaction product in the basal plasma membrane. The lack of demonstrable adenylate cyclase activity in the basal plasma membrane suggests the possibility that the basal plasma membrane may not play an important role of TSH-reception.