Bagchi N, Shivers B, Brown T R
Endocrinology. 1984 May;114(5):1652-6. doi: 10.1210/endo-114-5-1652.
There is a profound difference in the incidence of thyroid disease between males and females. We have investigated the possibility of a direct effect of sex steroids on the thyroid gland by investigating thyroid function in castrate animals. The rate of thyroid hormone release was estimated by measuring the rate of hydrolysis of labeled thyroglobulin from mouse thyroid glands in vitro. The thyroid glands were labeled in vivo with 131I and then cultured for 20 h in the presence of mononitrotyrosine, an inhibitor of iodotyrosine and deiodinase. The rate of hydrolysis of labeled thyroglobulin was measured as the percentage of radioactivity released as iodotyrosines and iodothyronines into the gland and the medium at the end of incubation. TSH was injected at varying intervals before death in some cases. The basal rates of thyroglobulin hydrolysis were similar in intact and castrate mice, but TSH-stimulated rates were significantly higher in both male and female castrates. Daily treatment of castrates for a week with estradiol or testosterone decreased the rate of thyroglobulin hydrolysis to that seen in intact mice, but dihydrotestosterone was without effect. (Bu)2cAMP added in vitro increased the rate of thyroglobulin hydrolysis in both intact and castrate mice, but the stimulation was significantly greater in the castrates. Basal and TSH-stimulated cAMP levels in the thyroid were similar in castrate and intact mice. There was no difference in thyroidal incorporation of iodine by intact and castrate mice in either presence or absence of TSH. These data suggest the following. 1) Castration results in significantly greater sensitivity to TSH with respect to thyroid hormone secretion. Thyroid hormone synthesis, basal or TSH-stimulated, is, however, unaltered. 2) Estradiol inhibits TSH-stimulated hormone release in castrates. Testosterone has a similar effect, possibly through aromatization to estradiol. 3) The effect of sex hormones is likely to be exerted at a post-cAMP step specific for hormone secretion.
甲状腺疾病的发病率在男性和女性之间存在显著差异。我们通过研究去势动物的甲状腺功能，探讨了性类固醇对甲状腺的直接作用。通过体外测量小鼠甲状腺中标记甲状腺球蛋白的水解速率来估计甲状腺激素释放率。甲状腺在体内用131I标记，然后在碘酪氨酸和脱碘酶抑制剂单硝基酪氨酸存在的情况下培养20小时。标记甲状腺球蛋白的水解速率通过在孵育结束时作为碘酪氨酸和碘甲状腺原氨酸释放到腺体和培养基中的放射性百分比来测量。在某些情况下，在处死前以不同间隔注射促甲状腺激素（TSH）。完整小鼠和去势小鼠的甲状腺球蛋白基础水解速率相似，但促甲状腺激素刺激的速率在雄性和雌性去势小鼠中均显著更高。用雌二醇或睾酮对去势小鼠进行为期一周的每日治疗可使甲状腺球蛋白水解速率降至完整小鼠的水平，但双氢睾酮无效。体外添加（Bu）2cAMP可增加完整小鼠和去势小鼠的甲状腺球蛋白水解速率，但在去势小鼠中的刺激作用明显更大。去势小鼠和完整小鼠甲状腺中的基础和促甲状腺激素刺激的环磷酸腺苷（cAMP）水平相似。在有或没有促甲状腺激素的情况下，完整小鼠和去势小鼠的甲状腺碘摄取没有差异。这些数据表明以下几点。1）去势导致甲状腺激素分泌对促甲状腺激素的敏感性显著增加。然而，基础或促甲状腺激素刺激的甲状腺激素合成未改变。2）雌二醇抑制去势小鼠中促甲状腺激素刺激的激素释放。睾酮有类似作用，可能是通过芳香化转化为雌二醇。3）性激素的作用可能在激素分泌特有的环磷酸腺苷后步骤发挥。
