Spona J
Endocrinol Exp. 1975 Jun;9(2):127-34.
The plasma membrane initiator system for actions of LH-RH was characterized. Binding of 125-I-LH-RH to the anterior pituitary plasma membrane was studied at 4 degrees C and at 37 degrees C. Two binding sites were indentified which possessed apparent affinity constants of 2 times 10- minus 8M and 2 times 10- minus 7M, respectively. The high affinity binding site was competible and saturable by TRH. These data suggest that the low affinity binding site is the physiological receptor for mediation of LH-RH stimulated LHrelease. LH-RH-receptor interaction has been shown to be a temperature and pH-dependent process. Less binding was observed at 37 degrees C than at 4 degrees C. Below pH 6 and above pH 8 a sharp drop in LH-RH binding to the cell membrane was recorded. Ca++, Mg++ and Mn++ were shown to inhibit the binding. Mn++ (16 mM) showed 50 percent inhibition of binding of LH-RH to the anterior pituitary plasma membrane fractions. On the other hand, increasing ionic strength enhanced LH-RH binding. The results of our study on the LH-RH-receptor systems offer a new approach to the study of LH-RH actions and facilitate the interpretation of earlier observations.
对促黄体生成激素释放激素（LH-RH）作用的质膜起始系统进行了表征。在4℃和37℃下研究了125-I-LH-RH与垂体前叶质膜的结合。鉴定出两个结合位点，其表观亲和常数分别为2×10⁻⁸M和2×10⁻⁷M。高亲和力结合位点可被促甲状腺激素释放激素（TRH）竞争并饱和。这些数据表明，低亲和力结合位点是介导LH-RH刺激促黄体生成素（LH）释放的生理受体。LH-RH与受体的相互作用已被证明是一个温度和pH依赖性过程。在37℃下观察到的结合比在4℃下少。在pH值低于6和高于8时，记录到LH-RH与细胞膜的结合急剧下降。钙离子（Ca++）、镁离子（Mg++）和锰离子（Mn++）被证明可抑制结合。锰离子（16 mM）对LH-RH与垂体前叶质膜部分的结合显示出50%的抑制作用。另一方面，增加离子强度可增强LH-RH的结合。我们对LH-RH受体系统的研究结果为LH-RH作用的研究提供了一种新方法，并有助于对早期观察结果的解释。
