Emerson C H, Lew R, Braverman L E, DeVito W J
Department of Medicine, University of Massachusetts Medical School, Worcester 01655.
Endocrinology. 1989 May;124(5):2415-8. doi: 10.1210/endo-124-5-2415.
To assess the relative role of circulating T4 and T3 in the regulation of serum TSH, we have measured serum T4, T3, and TSH concentrations in normal and thyroidectomized rats, some of which were chronically infused with T3 or T4. Serum T3, T4, and TSH concentrations were measured 7 and 14 days after surgery. Some groups of infused rats were mildly hypothyroid, as judged by elevated serum TSH concentrations. At both 7 and 14 days, there was a significant inverse correlation between serum T3 and serum TSH concentrations (day 7, r = 0.65, P less than 0.01; day 14, r = 0.71, P less than 0.01). The coefficients for the inverse correlations between serum T4 and TSH concentrations were 0.37 on day 7 (P less than 0.05) and 0.37 (P less than 0.05) on day 14. Linear regression analysis was performed using TSH as the dependent variable for outcome and serum T3 and T4 concentrations as the independent predictor variables. This analysis revealed that after controlling for T3, TSH and T4 were no longer significantly correlated (P = 0.14). The correlation between T3 and TSH remained highly significant. These results suggest that in the euthyroid and mildly hypothyroid rat, serum T3 has a greater inhibitory effect on TSH secretion than does serum T4.
为评估循环中的甲状腺素（T4）和三碘甲状腺原氨酸（T3）在血清促甲状腺激素（TSH）调节中的相对作用，我们测定了正常大鼠和甲状腺切除大鼠的血清T4、T3和TSH浓度，其中一些大鼠被长期输注T3或T4。在术后7天和14天测定血清T3、T4和TSH浓度。根据血清TSH浓度升高判断，一些输注大鼠组存在轻度甲状腺功能减退。在第7天和第14天，血清T3和血清TSH浓度之间均存在显著的负相关（第7天，r = 0.65，P<0.01；第14天，r = 0.71，P<0.01）。血清T4和TSH浓度之间的负相关系数在第7天为0.37（P<0.05），在第14天为0.37（P<0.05）。以TSH作为结果的因变量，血清T3和T4浓度作为自变量进行线性回归分析。该分析显示，在控制T3后，TSH和T4不再显著相关（P = 0.14）。T3和TSH之间的相关性仍然高度显著。这些结果表明，在甲状腺功能正常和轻度甲状腺功能减退的大鼠中，血清T3对TSH分泌的抑制作用大于血清T4。
