Adenylate cyclase system of porcine salivary gland and its relationship to thyrotropin
Chang, T.C.; Chang, T.J.; Huang, Y.S.; Chang, C.C.; Chen, F.W.
Journal of the Formosan Medical Association 86(12): 1245-1250
1987
ISSN/ISBN: 0371-7682 PMID: 2832514 Document Number: 303470
There is evidence that thyrotropin (TSH)-stimulated iodide transport of the thyroid is mediated by cyclic AMP (cAMP) and dependent on protein synthesis. The iodide concentrating ability of the salivary gland is not influenced by TSH in marked contrast to the thyroid. To elucidate why there is difference in iodide concentrating mechanism between the thyroid and the salivary gland, we used TSH-binding displacement assay, and adenylate cyclase assay stimulated by TSH,5'-guanylylimidodiphosphate (Gpp(NH)p) or forskolin, to study the TSH receptor and adenylate cyclase system in plasma membranes of the porcine thyroid and salivary gland. There were high affinity, low capacity TSH receptor and low affinity, high capacity TSH receptor in the porcine thyroid gland. However, only low affinity, high capacity TSH receptor was noted in the salivary gland. Increment of cAMP accumulations after TSH stimulation was noted in thyroid gland but not in the salivary gland. On the contrary, decrement of cAMP accumulations could be noted when 100 mU of TSH was added. Both Gpp(NH)p and forskolin increased the cAMP accumulations in the salivary gland. In the thyroid gland, Gpp(NH)p increased the cAMP accumulations. However, decrement of cAMP accumulations was noted when 10-7 M of forskolin was added and increment of cAMP accumulations when 10-5 M of forskolin was added. These findings suggest that the major reason why the iodide concentrating ability of the salivary gland is not influenced by TSH may be the absence of high affinity TSH receptor in the salivary gland.