Cacicedo L, Pohl S L, Reichlin S
Endocrinology. 1981 Mar;108(3):1012-9. doi: 10.1210/endo-108-3-1012.
Mouse thyrotropic tumor cells grown in primary culture were shown to synthesize TSH and proteins, as determined by the incorporation of radioactive proline into immunoprecipitable TSH and trichloroacetic acid-precipitable proteins. The net TSH content of the cells and medium determined by RIA is also increased during 24 h of incubation, and newly formed hormone is detected in the medium within 1 h after the addition of proline tracer. To study the effect of T4 and T3 on TSH synthesis, cultures were pulse-labeled with [3H]proline after they had been exposed to either T3 or T4. After 48 but not 24 h, exposure to either T3 or T4 was followed by inhibition. When studied after 48 h of incubation, T4, (10(-13) M) or T3 (10(-11) M) at the lowest concentration tested, was inhibitory to TSH synthesis. At concentrations of T4 and T3 greater than 10(-9) M, the inhibitory effects on TSH synthesis were partially reversed, suggesting a biphasic response. Incubation in TRH (10(-7) M) for 24 h led to a significant increase in TSH synthesis, total protein, acid-precipitable protein, and total DNA. The effect of TRH on TSH biosynthesis was a function of the logarithm of its concentration over the range of 10(-11)-10(-7) M. The inhibitory action of 10(-6) M T3 on TSH synthesis was reversed by exposure to 10(-10) or 10(-7) M TRH.
原代培养的小鼠促甲状腺肿瘤细胞经放射性脯氨酸掺入免疫沉淀的促甲状腺激素（TSH）和三氯乙酸沉淀蛋白测定，显示能合成TSH和蛋白质。在孵育24小时期间，通过放射免疫分析（RIA）测定的细胞和培养基中的净TSH含量也增加，并且在添加脯氨酸示踪剂后1小时内在培养基中检测到新形成的激素。为了研究T4和T3对TSH合成的影响，在培养物暴露于T3或T4后，用[3H]脯氨酸进行脉冲标记。48小时而非24小时后，暴露于T3或T4后出现抑制作用。在孵育48小时后进行研究时，测试的最低浓度的T4（10^(-13) M）或T3（10^(-11) M）对TSH合成具有抑制作用。当T4和T3的浓度大于10^(-9) M时，对TSH合成的抑制作用部分逆转，表明存在双相反应。在促甲状腺激素释放激素（TRH，10^(-7) M）中孵育24小时导致TSH合成、总蛋白、酸沉淀蛋白和总DNA显著增加。TRH对TSH生物合成的作用是其在10^(-11)-10^(-7) M范围内浓度对数的函数。暴露于10^(-10)或10^(-7) M的TRH可逆转10^(-6) M T3对TSH合成的抑制作用。
