title: Decreased expression of apelin in placentas from severe pre-eclampsia patients.
abstract: OBJECTIVE
  It is well documented that anti-angiogenic factors are likely to play essential roles in the etiology of pre-eclampsia. Apelin is a small peptide that may potentially act as an angiogenic factor. The expression of apelin was examined at the RNA and protein levels in this study.
  
  
  METHODS
  We compared the expression of apelin, examined using quantitative reverse-transcription polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay and immunostaining, between pre-eclamptic patients and normotensive controls.
  
  
  RESULTS
  Apelin messenger RNA is significantly decreased in pre-eclamptic placentas compared with normotensive pregnancies (p<0.05). Apelin protein levels are also lower in pre-eclamptic placentas than the controls but higher in the maternal circulation in pre-eclampsia patients. Immunohistochemical signals for apelin and its receptor APJ were detected mainly in the cytoplasm of syncytiotrophoblasts in chorionic villi and trophoblast-lineage cells in the decidua of term placentas. In early gestation, stronger APJ signals were observed at the cellular membrane.
  
  
  CONCLUSIONS
  A functional role of the apelin--APJ system is likely in early gestation, and this raises the possibility that a dysfunctional apelin--APJ system contributes to the onset of pre-eclampsia via decreased angiogenic activity in placental implantation.
authors.affiliation: Department of Obstetrics and Gynecology, Fujita Health University School of Medicine , Toyoake , Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Inuzuka
authors.forename: Haruki
authors.initials: H
authors.lastname: Nishizawa
authors.forename: Ayaka
authors.initials: A
authors.lastname: Inagaki
authors.forename: Machiko
authors.initials: M
authors.lastname: Suzuki
authors.forename: Sayuri
authors.initials: S
authors.lastname: Ota
authors.forename: Hironori
authors.initials: H
authors.lastname: Miyamura
authors.forename: Jun
authors.initials: J
authors.lastname: Miyazaki
authors.forename: Takao
authors.initials: T
authors.lastname: Sekiya
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurahashi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Udagawa
mesh_terms: D000328:Adult; D000073861:Apelin; D000075244:Apelin Receptors; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000209:etiology / Q000378:metabolism*; D011247:Pregnancy; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*
chemical_list: C115436:APLN protein, human; C104575:APLNR protein, human; D000073861:Apelin; D000075244:Apelin Receptors; D036341:Intercellular Signaling Peptides and Proteins; D043562:Receptors, G-Protein-Coupled