Roques M, Tirard A
J Endocrinol Invest. 1980 Apr-Jun;3(2):119-23. doi: 10.1007/BF03348237.
Phosphoprotamine phosphatase activity in the rat thyroid was examined by studying the release of inorganic phosphate from [32P]-phosphorylated protamine. Rats were given a normal diet supplemented or not with thyroxine (T4) (3 mg/l in 0.05% bovine serum albumin solution) or propylthiouracil (1 g/l in 1% sucrose solution) in drinking water for various periods. TSH was injected ip, 100 mU per animal. A significant increase of phosphatase specific activity-units per mg protein (3-fold) as well as units per gland- was observed following goitrogen treatment, whereas a decrease (50%) was seen in response to T4. Both the soluble and particle activities were similarly affected. As total activity decreased after T4 treatment, it appeared that only the Mn2+-stimulating enzyme was concerned, the Mn2+-unstimulated part remaining unaltered. In vitro cyclic AMP or cyclic GMP at concentrations from 10 micro M to 200 micro M had no effect on these phosphatase activities. TSH injected in chronically T4-treated rats (32 days treatment) failed to produce any significant enhancement in phosphatase activity whatever the time of injection before sacrifice (from 2 to 6 h). On the contrary a single injection of TSH in animals subjected to short treatment with T4 (2 days) induced an elevation of the enzyme activity, restoring partially the initial level. These findings suggest that TSH controls protein dephosphorylation activities in the thyroid. Furthermore, they offer additional evidence that prolonged T4 administration leads to decreased responsiveness to TSH.
通过研究[32P] -磷酸化鱼精蛋白中无机磷酸盐的释放，检测了大鼠甲状腺中的磷酸鱼精蛋白磷酸酶活性。给大鼠喂食正常饮食，并在不同时间段在饮用水中补充或不补充甲状腺素（T4）（在0.05%牛血清白蛋白溶液中为3mg/l）或丙硫氧嘧啶（在1%蔗糖溶液中为1g/l）。每只动物腹腔注射100mU促甲状腺激素（TSH）。致甲状腺肿药物处理后，观察到磷酸酶比活性（每毫克蛋白质的单位数，增加了3倍）以及每腺体的单位数显著增加，而T4处理后则出现下降（50%）。可溶性和颗粒活性受到的影响类似。由于T4处理后总活性降低，似乎仅涉及Mn2 +刺激的酶，Mn2 +未刺激的部分保持不变。浓度为10μM至200μM的体外环磷酸腺苷（cAMP）或环磷酸鸟苷（cGMP）对这些磷酸酶活性没有影响。在长期接受T4处理（32天）的大鼠中注射TSH，无论在处死前的注射时间（2至6小时）如何，均未能使磷酸酶活性产生任何显著增强。相反，在接受T4短期处理（2天）的动物中单次注射TSH会诱导酶活性升高，部分恢复初始水平。这些发现表明TSH控制甲状腺中的蛋白质去磷酸化活性。此外，它们提供了额外的证据，表明长期给予T4会导致对TSH的反应性降低。
