Study on the uterine contractile substance in human placenta

Research Project

Project/Area Number	61480353
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	Obstetrics and gynecology
Research Institution	Keio University
Principal Investigator	MAKINO Tsunehisa Department of Obstetrics and Gynecology,Keio University School of Medicine, 医学部・産婦人科, 専任講師 (30085758)
Co-Investigator(Kenkyū-buntansha)	MOTOYAMA Shizuo Department of Obstetrics and Gynecology,Keio University School of Medicine, 医学部・産婦人科, 助手 (30174353) SUGAHARA Masato Department of Obstetrics and Gynecology,Keio University School of Medicine, 医学部・産婦人科, 助手 (10162851) HAGINIWA Ichigen Department of Obstetrics and Gynecology,Keio University School of Medicine, 医学部・産婦人科, 助手 (60146652) NAKAZAWA Kazumi Department of Obstetrics and Gynecology,Keio University School of Medicine, 医学部・産婦人科, 助手 (30129556)
Project Period (FY)	1986 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥4,800,000 (Direct Cost: ¥4,800,000) Fiscal Year 1987: ¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1986: ¥2,800,000 (Direct Cost: ¥2,800,000)
Keywords	Oxytocin / Placenta / Rakioimmunoassay / Uterine contraction / Biosynthesis / Immynohistochemistry / Initiation of labor / 胎盤オキシトシン / オキシトシンのradioimmunoassay / 子宮収縮 / ニューロフィジン / 妊娠・分娩
Research Abstract	We have reported the existence of immunoreactive oxytocine(Ir-OT) in human placenta. In this study, we investigated the biophysical and biochemical properties of the placental exytocin. 1. Radioimmunoassy of oxytocin (OT) ; We obtained a highly sensitive and specific radioimmunoassay for OT. 2. Ir-OT content in placental tissue; Placenta was extracted with 0.04M acetic acid. Placental extract diluted paralled in RIA with synthetic OT and both eluted at the same position on CMC ion exchange chromatography.The placental tissue content of Ir- OT increases from 12. (minus-plus)5.61ng/placenta in the first trimester to 4.1(minus-plus)0.41(minus-plus)g/placenta in the second trimester, and continually increased to 12.5(minus-plus)1.22(minus-plus)g/placenta in the third trimester.The concentration of placental Ir-OT significantly increased from the 1.6(minus-plus)0.29ng/gm tissue of the first trimesterto the 20.8(minus-plus))1.90ng/gm of the second trimester,maintaining this level until the th … More ird trimester. 3. Bioactivity of placental OT; Synthetic OT and placental extract induced marked contraction of rat uterine muscle on a Magnus apparatus and the placental extract previously incubated with OT antiserum failed to induce the same contraction, suggesting that OT-like substance in the human placenta posseses uterine contractile activity. 4. Immunohistochemical localization of placental OT; Placental OT was identified to localize in syncytiotrophoblast of the placental tissue by the PAP immunohistochemical method. 5.Biosynthesis of placental OT; Ir-OT content per am of the placental tissue was significantly decreased after 24 hours of incubation when cyclohexamide,an inhibitory agent of protein biosynthesis, was added to the culture medium suggesting the possibility of the biosynthesis of Ir-OT in the placental tissue. 6.Purification of placental OT; Sephadex G 25 gel filtration revealed two molecular forms of placental OT.The smaller one eluted almost at the same position as synthetic OT and identified to posses potent contractile effect on rat uterine muscle. Further purification and presice biochemical characterization of this OT-like substance in the human placenta with contractile effect on uterine muscle can be a key to elucidate the mechanisms of initiation of human labor. Less