title: Estradiol upregulates the expression of oxytocin receptor in colon in rats.
abstract: 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.
authors.affiliation: Department of Physiology, Medical School of Shandong University, Jinan 250012, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Feng
authors.forename: Junfang
authors.initials: J
authors.lastname: Qin
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Ye
authors.forename: Shuanglian
authors.initials: S
authors.lastname: Wang
authors.forename: Dongping
authors.initials: D
authors.lastname: Xie
authors.forename: Paulus S
authors.initials: PS
authors.lastname: Wang
authors.forename: Chuanyong
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D030762:Estrous Cycle / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D006727:Hormone Antagonists / Q000494:pharmacology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D010052:Ovariectomy; D010121:Oxytocin / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D018045:Receptors, Oxytocin / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects; D014668:Vasotocin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D006727:Hormone Antagonists; D012333:RNA, Messenger; D018045:Receptors, Oxytocin; C047046:atosiban; D004958:Estradiol; D010121:Oxytocin; D014668:Vasotocin