Sairam M R, Manjunath P
J Biol Chem. 1983 Jan 10;258(1):445-9.
The biological properties of chemically deglycosylated human choriogonadotropin (DG-hCG) preparations were examined in collagenase-dispersed rat interstitial cells in vitro. Despite effective receptor binding activity in membrane preparations, DG-hCG failed to induce cyclic AMP accumulation in the cells when incubated in the presence or absence of a phosphodiesterase inhibitor. The steroidogenic ability as assessed by testosterone accumulation in the medium was less than 0.5% of the native hormone with a failure to attain maximal steroid production. Time course experiments have revealed that altered kinetics could not be responsible for the loss of hormone response. Consistent with its property of good receptor binding and poor cell activation, DG-hCG antagonized the action of native hCG. When added to the cells at the same time, DG-hCG inhibited the action of a maximal stimulatory dose of hCG in a dose-dependent manner. Inhibition of cyclic AMP accumulation was complete whereas inhibition of steroidogenesis was about 75%. DG-hCG had no effect on the stimulatory action of cholera toxin in interstitial cells or that of follitropin in rat seminiferous tubular preparations. The data suggest that DG-hCG has a conformation conductive for effective interaction with the receptor, but its ability to activate the adenylate cyclase is either lost or weakly expressed.
在体外对胶原酶分散的大鼠间质细胞中化学去糖基化人绒毛膜促性腺激素（DG-hCG）制剂的生物学特性进行了研究。尽管在膜制剂中具有有效的受体结合活性，但在存在或不存在磷酸二酯酶抑制剂的情况下孵育时，DG-hCG未能诱导细胞中环磷酸腺苷（cAMP）的积累。通过培养基中睾酮积累评估的类固醇生成能力不到天然激素的0.5%，且无法达到最大类固醇产量。时间进程实验表明，动力学改变并非激素反应丧失的原因。与其良好的受体结合和较差的细胞激活特性一致，DG-hCG拮抗天然hCG的作用。当与细胞同时添加时，DG-hCG以剂量依赖性方式抑制最大刺激剂量hCG的作用。cAMP积累的抑制是完全的，而类固醇生成的抑制约为75%。DG-hCG对霍乱毒素在间质细胞中的刺激作用或促卵泡激素在大鼠生精小管制剂中的刺激作用均无影响。数据表明，DG-hCG具有有利于与受体有效相互作用的构象，但其激活腺苷酸环化酶的能力要么丧失，要么表达较弱。
