Baxter R C, Zaltsman Z, Turtle J R
Endocrinology. 1982 Sep;111(3):1020-2. doi: 10.1210/endo-111-3-1020.
Male and female Wistar-Furth rats bearing the pituitary tumor MtT/W15 had serum GH and PRL levels several hundred-fold higher, and immunoreactive somatomedin levels 3-fold higher, than those of controls. The presence of tumor appeared to have no effect on specific binding of radioiodinated bovine GH to liver microsomal membranes in male animals, and to decrease specific binding by 78% in females. However, after desaturating receptors by treatment with 3.2 M MgCl2 for 5 min, bovine GH binding to membranes from tumor-bearing males was 3-fold higher than in normal males, while in tumor-bearing females binding was more than twice as high as in normal females. Competitive binding curves showed the induced receptors to be specific for growth hormones, and thus somatogenic in nature. This study indicates that a high degree of occupancy of GH receptors in hypersomatotropic rat liver does not cause their down-regulation. The mechanism of receptor induction is unknown.
患有垂体肿瘤MtT/W15的雄性和雌性Wistar-Furth大鼠，其血清生长激素（GH）和催乳素（PRL）水平比对照组高数百倍，免疫反应性生长调节素水平比对照组高3倍。肿瘤的存在似乎对雄性动物肝脏微粒体膜上放射性碘化牛GH的特异性结合没有影响，而在雌性动物中则使特异性结合降低78%。然而，在用3.2 M MgCl2处理5分钟使受体去饱和后，牛GH与荷瘤雄性动物肝脏膜的结合比正常雄性动物高3倍，而在荷瘤雌性动物中，结合比正常雌性动物高两倍多。竞争性结合曲线表明，诱导产生的受体对生长激素具有特异性，因此本质上是促生长的。这项研究表明，高生长激素血症大鼠肝脏中生长激素受体的高度占据不会导致其下调。受体诱导的机制尚不清楚。
