Cyclic AMP release from normal human thyroid slices in response to thyrotrophin

Publisher Website
Google Scholar
Abstract
Slice preparations of normal human thyroid tissue were incubated in vitro with TSH [thyrotropin]. The cAMP contents of slices were determined at intervals up to 120 min, and cAMP in the incubation medium was also estimated for each incubation period. Slice cAMP levels were related both to incubation time and TSH dose. In response to 10 mU TSH/ml, slice cAMP levels were maximal within 60 min, and were not significantly changed at 120 min. cAMP was detectable in the medium within 10 min of slice exposure to TSH, and increased throughout the initial 60 min of incubation. cAMP release during this period was dependent on both TSH dose and incubation time. Between 60-120 min, cAMP release partially lost its TSH dose-dependency, and 0.5-5.0 mU TSH/ml were equipotent with respect to the final medium cAMP level attained. Slices incubated without TSH released only small amounts of cAMP, and maximal levels were attained within 20 min. In contrast to the adenylate cyclase response of thyroid membrane preparations, which was stimulated by NaF, suggesting that cAMP release was not a result of the stimulation of damaged cells. These findings demonstrate the importance of cAMP release from human thyroid slices, following in vitro exposure to TSH, and suggest that, after incubation periods such as are used for the functional biodetection of thyroid stimulators, the magnitude of cAMP release may be of quantitative significance.