Chen F, Goto S, Furuhashi Y, Saito M, Kinoshita Y, Sugiyama M, Okamoto T, Tomoda Y
Department of Obstetrics and Gynecology, Nagoya University School of Medicine.
Nihon Sanka Fujinka Gakkai Zasshi. 1988 Jun;40(6):769-74.
We developed a radioreceptor assay (RRA) system for investigating occupied hCG receptors by using a rat testis membrane fraction. Treatment with dithiothreitol, neuraminidase, and low pH (3.3) buffer partially dissociated hCG from its receptor with dissociation rates of 42.8%, 35.2%, and 68.7%, respectively. Specific receptor rebinding was unaffected and showed competitive inhibition of [125I]hCG rebinding by unlabeled hCG. Scatchard plot analysis yielded a rebinding Km of 1.798-3.496/pM. High concentrations of NaCl and MgCl2 had no obvious effect on the [125I]hCG-receptor complex. Triton X-100 and high concentration MnCl2 treatments resulted in the loss of the receptor rebinding activity. We also investigated human chorionic tissue (at 8 weeks, 11 weeks, 16 weeks, 24 weeks, and term) for hCG receptors using the above method. Treatments with different agents increased [125I]hCG binding in this tissue preparation 139-226%, but Scatchard analysis failed to demonstrate any specificity. [125I]hCG uptake by the choriocarcinoma BeWo cell-line increased 151-193% after similar treatments, but this increase could not be competitively inhibited by unlabeled hCG. Treatment with dithiothreitol, neuraminidase, and low pH (3.3) buffer seems feasible for detecting hCG-occupied receptors. Our results suggest that there are no hCG receptors distributed on the surface of the syncytiotrophoblast of human placenta.
我们开发了一种放射受体分析（RRA）系统，用于通过使用大鼠睾丸膜部分来研究被占据的人绒毛膜促性腺激素（hCG）受体。用二硫苏糖醇、神经氨酸酶和低pH（3.3）缓冲液处理可使hCG与其受体部分解离，解离率分别为42.8%、35.2%和68.7%。特异性受体再结合不受影响，并显示未标记的hCG对[125I]hCG再结合具有竞争性抑制作用。Scatchard作图分析得出再结合的米氏常数（Km）为1.798 - 3.496/pM。高浓度的氯化钠（NaCl）和氯化镁（MgCl2）对[125I]hCG - 受体复合物没有明显影响。Triton X - 100和高浓度氯化锰（MnCl2）处理导致受体再结合活性丧失。我们还使用上述方法研究了人绒毛膜组织（8周、11周、16周、24周和足月时）中的hCG受体。用不同试剂处理可使该组织制剂中[125I]hCG结合增加139 - 226%，但Scatchard分析未能证明任何特异性。类似处理后，绒毛膜癌BeWo细胞系对[125I]hCG的摄取增加了151 - 193%，但这种增加不能被未标记的hCG竞争性抑制。用二硫苏糖醇、神经氨酸酶和低pH（3.3）缓冲液处理似乎对检测被hCG占据的受体是可行的。我们的结果表明，人胎盘合体滋养层表面没有hCG受体分布。
