title: The rat placental renin-angiotensin system - a gestational gene expression study.
abstract: BACKGROUND
  The placenta is an essential organ that provides nutrients and oxygen to the developing fetus and removes toxic waste products from the fetal circulation. Maintaining placental blood osmotic pressure and blood flow is crucial for viable offspring. The renin-angiotensin system (RAS) in the placenta is a key player in the regulation of maternal-fetal blood flow during pregnancy. Therefore, the aim of this study was to determine if RAS genes are differentially expressed in mid to late gestation in rat placenta.
  
  
  METHODS
  Whole placental tissue samples from pregnant Sprague Dawley rats at embryonic (E) days 14.25, 15.25, 17.25 and 20 (n = 6 for each gestational age) were used for genome-wide gene expression by microarray. RAS genes with expression differences of >2 fold were further analyzed. Quantitative Real-Time PCR (qPCR) was performed on independent samples to confirm and validate microarray data. Immunohistochemisty and Western blotting were performed on a differentially expressed novel RAS pathway gene (ANPEP).
  
  
  RESULTS
  Six out of 17 genes of the RAS pathway were differentially expressed at different gestational ages. Gene expression of four genes (Angiotensin converting enzyme (Ace), angiotensin converting enzyme 2 (Ace2), membrane metalloendopeptidase (Mme) and angiotensin II receptor 1A (Agtr1a)) were significantly upregulated at E20 whereas two others (Thimet oligopeptidase 1 (Thop1) and Alanyl aminopeptidase (Anpep)) were downregulated at E20 prior to the onset of labour. These changes were confirmed by qPCR. Western blots revealed no overall differences in ANPEP protein expression in the placentae. Immunohistochemical studies, however, indicated that the localization of ANPEP differed at E17.25 and E20 as ANPEP localization in the giant trophoblast cell of the junctional zone was no longer detectable at E20.
  
  
  CONCLUSIONS
  The current study investigated the expression of members of the RAS pathway in rat placentae and observed significantly altered expression of 6 RAS genes at 4 gestational ages. These findings present the need for further comprehensive investigation of RAS genes in normal and complicated pregnancies.
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. k.vaswani@uq.edu.au.
authors.forename: Kanchan
authors.initials: K
authors.lastname: Vaswani
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. h.chan4@uq.edu.au.
authors.forename: Hsiu-Wen
authors.initials: HW
authors.lastname: Chan
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. paliverma@gmail.com.
authors.forename: Pali
authors.initials: P
authors.lastname: Verma
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. m.dekker@uq.edu.au.
authors.forename: Marloes
authors.initials: M
authors.lastname: Dekker Nitert
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. h.peiris@uq.edu.au.
authors.forename: Hassendrini N
authors.initials: HN
authors.lastname: Peiris
authors.affiliation: Department of Anatomy & Developmental Biology Monash University, Clayton, VIC, 3800, Australia. r.woodbradley@deakin.edu.au.|School of Medicine (Optometry), Deakin University, Pigdons Road, Waurn Ponds, VIC, 3800, Australia. r.woodbradley@deakin.edu.au.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Wood-Bradley
authors.affiliation: Department of Anatomy & Developmental Biology Monash University, Clayton, VIC, 3800, Australia. James.Armitage@bakeridi.edu.au.|School of Medicine (Optometry), Deakin University, Pigdons Road, Waurn Ponds, VIC, 3800, Australia. James.Armitage@bakeridi.edu.au.
authors.forename: James A
authors.initials: JA
authors.lastname: Armitage
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. g.rice@uq.edu.au.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Rice
authors.affiliation: Centre for Clinical Diagnostics, University of Queensland Centre for Clinical Research Royal Brisbane and Women's Hospital Campus, Building 71/918, Royal Brisbane Hospital, Herston, QLD, 4029, Australia. murray.mitchell@uq.edu.au.
authors.forename: Murray D
authors.initials: MD
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012084:Renin-Angiotensin System / Q000502:physiology*