Adachi S, Oku M
Department of Obstetrics and Gynecology, Saiseikai Tyuwa Hospital, Nara.
Nihon Sanka Fujinka Gakkai Zasshi. 1995 Feb;47(2):87-93.
Myometrial contraction induced by oxytocin (OT) is dependent on the OT concentration and the number of OT receptors (OTR) expressed. We previously reported that the number of myometrial OTR expressed is regulated by estradiol and progesterone in myometrial cell culture. In the present study, we evaluate the change in the number of OTR expressed on the cell surface after the addition of OT. After OT was added under various conditions to myometrial cells, we measured the number of OTR expressed on the cell surface (surface-OTR) and those in the plasma membrane (PM) (total-OTR). 1. After the addition of 1 nM OT, total-OTR was 25.78 fmol/mg protein in the OT-negative control and was 23.66 and 7.88 at 30 minutes and 24 hours. 2. Surface-OTR showed no changes after the addition of 1 nM OT at 4 degrees C, and the value after 60 minutes was 8.90 fmol/mg protein. At 37 degrees C, however, it become 5.53 and 1.72 fmol/mg protein 60 minutes after the addition of OT at 10pM and 10nM. This decrease in surface-OTR was suppressed by concanavalin A (ConA), which inhibits the internalization of receptors. Our study demonstrated that OTR expressed on the surface of myometrial cells decreased rapidly in the presence of OT due to internalization.
催产素（OT）诱导的子宫肌层收缩取决于OT浓度和所表达的OT受体（OTR）数量。我们之前报道过，在子宫肌层细胞培养中，所表达的子宫肌层OTR数量受雌二醇和孕酮调节。在本研究中，我们评估了添加OT后细胞表面所表达的OTR数量的变化。在各种条件下向子宫肌层细胞添加OT后，我们测量了细胞表面（表面OTR）和质膜（PM）中（总OTR）所表达的OTR数量。1. 添加1 nM OT后，OT阴性对照中的总OTR为25.78 fmol/mg蛋白，在30分钟和24小时时分别为23.66和7.88。2. 在4℃添加1 nM OT后，表面OTR没有变化，60分钟后的数值为8.90 fmol/mg蛋白。然而，在37℃，在添加10 pM和10 nM OT 60分钟后，其分别变为5.53和1.72 fmol/mg蛋白。这种表面OTR的减少被伴刀豆球蛋白A（ConA）抑制，ConA可抑制受体的内化。我们的研究表明，由于内化作用，在OT存在的情况下，子宫肌层细胞表面所表达的OTR迅速减少。
