Hupart K H, DeFesi C R, Katz C P, Shapiro L E, Surks M I
Department of Medicine, Montefiore Medical Center, Bronx, New York 10467.
Endocrinology. 1990 Jan;126(1):616-21. doi: 10.1210/endo-126-1-616.
To continue our studies on the influence of T3 on TSH regulation in the Walker 256 carcinoma-bearing rat model of nonthyroidal disease, we measured the effect of T3 on pituitary content of beta TSH mRNA and rat (r) TSH in hypothyroid control (C) and tumor-bearing (T) rats. The effect of T3 on TSH regulation was compared to effects on GH mRNA and rGH in the same animals. mRNA content was normalized to a pool of pituitaries from euthyroid rats (= 1.0). beta TSH mRNA increased 18-fold in both hypothyroid C and T rats and then decreased similarly with increasing T3 infusion to a value of 0.1. GH mRNA content decreased to 0.11 +/- 0.01 in hypothyroid C rats, but to only 0.38 +/- 0.02 in T rats (P less than 0.001). The pituitary contents of GH mRNA and rGH in hypothyroid T rats was significantly greater than those in C rats at all T3 infusion rates. These data together with our previous report of decreased nuclear T3 in T rats suggest that regulation of beta TSH mRNA by T3 is intact in T rats, but occurs at a lower concentration of nuclear T3. In contrast, the GH mRNA response is enhanced, displaying differential regulation of these two T3-responsive gene products in this model of nonthyroidal illness.
为了继续我们对三碘甲状腺原氨酸（T3）对非甲状腺疾病的Walker 256荷瘤大鼠模型中促甲状腺激素（TSH）调节影响的研究，我们测量了T3对甲状腺功能减退的对照（C）大鼠和荷瘤（T）大鼠垂体中β-TSH mRNA含量及大鼠（r）TSH的影响。将T3对TSH调节的影响与对同一动物生长激素（GH）mRNA和rGH的影响进行了比较。mRNA含量以甲状腺功能正常大鼠的垂体混合样本为参照进行标准化（=1.0）。在甲状腺功能减退的C组和T组大鼠中，β-TSH mRNA均增加了18倍，随后随着T3输注量增加而同样下降至0.1。在甲状腺功能减退的C组大鼠中，GH mRNA含量降至0.11±0.01，但在T组大鼠中仅降至0.38±0.02（P<0.001）。在所有T3输注率下，甲状腺功能减退的T组大鼠垂体中GH mRNA和rGH的含量均显著高于C组大鼠。这些数据以及我们之前关于T组大鼠核内T3减少的报告表明，T3对β-TSH mRNA的调节在T组大鼠中是完整的，但发生在较低浓度的核内T3水平。相比之下，GH mRNA反应增强，在这种非甲状腺疾病模型中显示出这两种T3反应性基因产物的差异调节。
