Rapoport B, Adams R J, Rose M
Medical Service, Veterans Administration Hospital, San Francisco, California 94121.
Endocrinology. 1977 Mar;100(3):755-64. doi: 10.1210/endo-100-3-755.
Unlike in all other thyroid preparations, exposure of dog thyroid cells in long-term monolayer culture to iodide (10(-7) to 10(-3) M for up to 19 h did not blunt the subsequent adenosine 3', 5'-cyclic monophosphate (cAMP) response to thyrotropin (TSH) stimulation. This lack of effect of iodide was observed even when confluent thyroid cells were "follicularized" by the action of TSH in the culture medium. Preincubation of these cells in thyroxine (T4) and triiodothyronine (T3) was similarly without effect on the subsequent cAMP response to TSH. Study of thyroid cells during the early phase of primary culture demonstrated that inhibition by iodide (10(-4) M) of the cAMP response to TSH occurred after 7 h but was lost after 48 h of cell culture. This inhibitory effect of iodide was prevented by the inclusion of methimazole in the preincubation medium. As with iodide-insensitive cells, T4 and T3 were without effect on the cAMP response to TSH in iodide-sensitive thyroid cells. Exposure of iodide-insensitive thyroid cells to iodide-containing medium obtained after 2 h of incubation with dog thyroid slices, as well as to medium enriched with the 100,000 g supernatant fraction of homogenates prepared from these thyroid slices, did not restore the inhibitory action of iodide. However, iodide-sensitivity of the cAMP response to TSH was restored by preincubation of iodide-insensitive cells in 10(-4) M iodide plus an H2O2-generating system (glucose-glucose oxidase). These data suggest that T4 and T3 are not organic iodine inhibitors of the thyroid cAMP response to TSH. In addition, they provide evidence against the existence of a soluble, freely diffusible, organic iodine inhibitor of thyroid adenylate cyclase. The loss of sensitivity to iodide inhibition of adenylate cyclase that occurs in thyroid cells shortly after initiation of primary culture appears to be related to a defect in the cellular organification mechanism, possibly the H2O2-generating system.
与所有其他甲状腺制剂不同，长期单层培养的犬甲状腺细胞暴露于碘化物（10⁻⁷至10⁻³M，长达19小时）并不会减弱随后对促甲状腺激素（TSH）刺激的腺苷3'，5'-环磷酸（cAMP）反应。即使汇合的甲状腺细胞通过培养基中TSH的作用“滤泡化”，也观察到碘化物缺乏这种作用。这些细胞在甲状腺素（T4）和三碘甲状腺原氨酸（T3）中预孵育同样对随后对TSH的cAMP反应没有影响。对原代培养早期阶段的甲状腺细胞研究表明，碘化物（10⁻⁴M）对TSH的cAMP反应的抑制在细胞培养7小时后出现，但在48小时后消失。预孵育培养基中加入甲巯咪唑可防止碘化物的这种抑制作用。与对碘化物不敏感的细胞一样，T4和T3对碘化物敏感的甲状腺细胞中对TSH的cAMP反应没有影响。将对碘化物不敏感的甲状腺细胞暴露于与犬甲状腺切片孵育2小时后获得的含碘化物培养基中，以及暴露于富含这些甲状腺切片制备的匀浆100,000g上清液部分的培养基中，并未恢复碘化物的抑制作用。然而，通过将对碘化物不敏感的细胞在10⁻⁴M碘化物加H₂O₂生成系统（葡萄糖-葡萄糖氧化酶）中预孵育，可恢复对TSH的cAMP反应的碘化物敏感性。这些数据表明，T4和T3不是甲状腺对TSH的cAMP反应的有机碘抑制剂。此外，它们提供了证据反对存在可溶性、可自由扩散的甲状腺腺苷酸环化酶有机碘抑制剂。原代培养开始后不久甲状腺细胞中发生的对腺苷酸环化酶碘化物抑制敏感性的丧失似乎与细胞有机化机制的缺陷有关，可能是H₂O₂生成系统。
