Zimniski S J, Rorke E A, Sickel M A, Vaitukaitis J L
Endocrinology. 1982 Aug;111(2):625-34. doi: 10.1210/endo-111-2-625.
The current studies were designed to ascertain the fate of hCG bound to rat corpora luteal cell receptors. Graded doses of highly purified hCG (CR119), ranging from 0.1-10.1 micrograms, were injected. Groups of pseudopregnant rats received iodinated hCG, unlabeled hCG, or both. Supraphysiological levels of hCG were used to enhance the internalization of hCG and its receptors. When ovarian membrane pellets (48,000 X g) were subjected to continuous sucrose density ultracentrifugation, two different ovarian membrane fractions (F1 and F2) bound hCG. Although an increase in hCG binding to the F2 membrane fraction was observed between 1-6 h after a single 0.1-microgram [125I]iodo-hCG injection, no subsequent enhanced binding to that fraction was observed. However, the F1 fraction bound at least 3 fold more hCG than did the F2 fraction 1, 6, 12, and 24 h after the injection of 0.1 micrograms [125I]iodo-hCG. When groups of animals were injected with 0.1, 1.0, or 10.0 micrograms unlabeled highly purified hCG, peak serum, ovarian plasma membrane, and ovarian intracellular hCG concentrations were observed at different times after hormone injection and suggested the progressive transfer of hCG from serum to ovarian fractions in a time- and dose-dependent relationship. Although no intracellular hCG was detected until 60 min after the single 0.1-microgram injection of hCG, both serum and membrane-bound levels were measurable within 15 min of that injection. From these observations, we suggest that ovarian intracellular hCG does not reflect significant contamination with serum or interstitial fluid or from significant dissociation of membrane-bound hCG during tissue handling. Finally, when intracellular hCG was subjected to continuous sucrose density gradient ultracentrifugation, a single major 135I peak was observed, and this comigrated with [125I]iodo-hCG. Our interpretation of the foregoing observations is that the major intracellular form of hCG is not receptor bound.
当前的研究旨在确定与大鼠黄体细胞受体结合的人绒毛膜促性腺激素（hCG）的去向。注射了0.1至10.1微克不等的分级剂量高度纯化的hCG（CR119）。假孕大鼠组分别接受碘化hCG、未标记的hCG或两者。使用超生理水平的hCG来增强hCG及其受体的内化。当卵巢膜沉淀物（48,000×g）进行连续蔗糖密度超速离心时，两种不同的卵巢膜组分（F1和F2）结合hCG。尽管在单次注射0.1微克[125I]碘hCG后1至6小时观察到hCG与F2膜组分的结合增加，但随后未观察到该组分结合增强。然而，在注射0.1微克[125I]碘hCG后1、6、12和24小时，F1组分结合的hCG比F2组分至少多3倍。当给动物组注射0.1、1.0或10.0微克未标记的高度纯化hCG时，在激素注射后的不同时间观察到血清、卵巢质膜和卵巢细胞内hCG的峰值浓度，这表明hCG以时间和剂量依赖的关系从血清逐渐转移到卵巢组分中。尽管在单次注射0.1微克hCG后60分钟才检测到细胞内hCG，但在注射后15分钟内血清和膜结合水平均可测量。基于这些观察结果，我们认为卵巢细胞内hCG并不反映血清或组织液的显著污染，也不反映组织处理过程中膜结合hCG的显著解离。最后，当细胞内hCG进行连续蔗糖密度梯度超速离心时，观察到一个单一的主要135I峰，并且该峰与[125I]碘hCG共同迁移。我们对上述观察结果的解释是，hCG的主要细胞内形式不是与受体结合的。
