Effect of thyroid-stimulating hormone and norepinephrine on cyclic AMP levels in human normal thyroids and human thyroid tumors.

The effect of TSH (100mU/ml) and norepinephrine (100 muM) on the cyclic AMP levels was studied in 10 human normal tissues, 10 thyroid adenomas and 4 thyroid carcinomas (3 papillary and 1 follicular). Normal tissues responded to TSH with a marked elevation of the cyclic AMP level. Response patterns of 10 thyroid adenomas to TSH were variable; the patterns of 6 cases resembled those of normal tissues, 3 responded mildly, and one had no response to TSH. Thyroid carcinomas had a higher basal level of cyclic AMP than those of normal tissues, although they responded only slightly to TSH. Two among 4 thyroid carcinomas had no response to TSH. Norepinephrine stimulated the accumulation of cyclic AMP in 4 thyroid adenomas and 3 thyroid carcinomas, while it had little effect on normal tissues. Responses to norepinephrine was observed only in thyroid tumors, although they had low response to TSH. It is suggested from these results that tumor cells originating from thyroid follicular cells have a modified response to hormones due to neoplastic alterations.