Feng Mei, Qin Junfang, Wang Chao, Ye Yanfang, Wang Shuanglian, Xie Dongping, Wang Paulus S, Liu Chuanyong
Department of Physiology, Medical School of Shandong University, Jinan 250012, China.
Am J Physiol Endocrinol Metab. 2009 May;296(5):E1059-66. doi: 10.1152/ajpendo.90609.2008. Epub 2009 Mar 3.
The study was designed to investigate the effect of estradiol on the excitatory effect of oxytocin (OT) on colon motility. Female Wistar rats were used, and some of them were ovariectomized (OVX) and treated with vehicle or estradiol (E(2)). A plastic balloon made of condom was inserted into colon to monitor the change of colonic pressure in vivo. Longitudinal muscle strips of distal colon were prepared to monitor the spontaneous contraction of colon in vitro. Expression of OT receptor (OTR) was investigated by Western blot analysis. Expression of OTR mRNA was detected by RT-PCR. Immunohistochemistry was used to locate OTR. In OVX rats, pretreatment of E(2) (4-100 microg/kg sc) dose-dependently increased the excitatory effect of OT on colon motility both in vivo and in vitro and increased the expression of OTR and OTR mRNA in colon. Systemic administration of OT excited the colon motility in vivo in rats at perioda of proestrus and estrus but did not influence it at diestrus period, when the concentration of plasma E(2) was lowest in the estrous cycle. Pretreatment of atosiban, the specific OTR antagonist, and TTX, the blocker of voltage-dependent sodium channel on nerve fiber, attenuated the excitatory effect of OT on colon motility. OTR was located in myenteric plexus of colon. These results suggested that E(2) increased the excitatory effect of OT on colon motility by upregulating the expression of OTR in myenteric plexus.
本研究旨在探讨雌二醇对催产素（OT）兴奋结肠运动作用的影响。选用雌性Wistar大鼠，部分大鼠行卵巢切除术（OVX），并给予溶剂或雌二醇（E₂）处理。将由避孕套制成的塑料球囊插入结肠以监测体内结肠压力的变化。制备远端结肠纵行肌条以监测体外结肠的自发收缩。通过蛋白质印迹分析研究OT受体（OTR）的表达。通过逆转录-聚合酶链反应（RT-PCR）检测OTR mRNA的表达。采用免疫组织化学法定位OTR。在OVX大鼠中，E₂（4 - 100μg/kg皮下注射）预处理剂量依赖性地增强了OT对体内和体外结肠运动的兴奋作用，并增加了结肠中OTR和OTR mRNA的表达。全身给予OT可兴奋处于动情前期和动情期大鼠的体内结肠运动，但在动情间期不产生影响，此时动情周期中血浆E₂浓度最低。特异性OTR拮抗剂阿托西班和神经纤维电压依赖性钠通道阻滞剂河豚毒素预处理减弱了OT对结肠运动的兴奋作用。OTR位于结肠肌间神经丛。这些结果提示，E₂通过上调肌间神经丛中OTR的表达增强了OT对结肠运动的兴奋作用。
