Short Communication Corticotrophin-releasing Factor and Urocortin Inhibit System A Activity in Term Human Placental Villous Explants A. Giovannelli a , S.L. Greenwood b , M. Desforges b, * , C.P. Sibley b , F. Petraglia a a Department of Pediatrics, Obstetrics and Reproductive Medicine, Section of Obstetric and Gynecology, University of Siena, Siena, Italy b Maternal and Fetal Health Research Centre, School of Biomedicine, University of Manchester, St Mary’s Hospital, Oxford Road, Level 5 e Research, Manchester, M13 9WL, United Kingdom article info Article history: Accepted 29 October 2010 Keywords: Syncytiotrophoblast MeAIB SNAT Hormones abstract Plasma corticotrophin-releasing factor (CRF) and urocortin are elevated in preterm labour and/or fetal growth restriction (FGR). FGR is associated with reduced placental system A amino acid transporter activity and in vitro data suggest altered endocrine status could be responsible. Here we test the hypothesis that CRF and urocortin inhibit placental system A activity. Chronic (48 h) exposure of term placental villous explants to these hormones (10 7 M) significantly reduced system A activity (Na þ -dependent 14 C-methylaminoisobutyric acid uptake), whereas 1 h exposure had no effect. We propose elevated CRF and urocortin contribute to FGR through negative regulation of placental system A activity. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The human placenta secretes numerous hormones and vasoac- tive factors into the fetal and maternal circulations. These factors act in an endocrine, autocrine and paracrine fashion to adapt maternal metabolism to the specific requirements of pregnancy, promote placental development, maintain adequate blood flow to the fetal-placental unit, and regulate placental transfer of nutrients required for fetal growth. Corticotrophin-releasing factor (CRF) and urocortin (UCN) are two such factors produced and secreted by the placenta [1e4]. CRF and UCN exert their effects via activation of corticotropin-releasing factor receptor 1 and 2 (CRF-R1 and CRF- R2) [5e7], widely expressed in reproductive tissues including placenta [8,9], suggesting a local physiological role for these hormones in regulating placental function. Indeed there is evidence that both can modulate placental vascular tone [10e12]. The concentrations of CRF and UCN in maternal and cord plasma are elevated in pregnancies complicated by preterm labour, and/or maternal hypertension, associated with fetal growth restriction (FGR) [13]. Fetal plasma amino acids are significantly lower in FGR compared to normal pregnancies [14,15]. Furthermore, FGR is associated with reduced system A amino acid transporter activity in the placenta and this reduction is related to the severity of FGR [16,17]. The mechanisms responsible for reduced placental system A activity in FGR are poorly understood but it is possible that altered endocrine regulation could contribute [18]. Despite the association between FGR and elevated maternal and fetal plasma levels of CRF and UCN, their effects on placental amino acid transport have yet to be determined. The aim of this study was to test the hypothesis that CRF and UCN downregulate system A activity in the human placenta. 2. Materials and methods 2.1. Materials Chemicals were purchased from SigmaeAldrich Co. Ltd (Poole, UK) or VWR International (Lutterworth, UK) unless otherwise stated. 2.2. Tissue acquisition and ethical approval Term placentae (38e40 weeks gestation) were collected from the Central Delivery Unit at St. Mary’s Hospital (Manchester, UK) with written informed consent, in accordance with Local Ethics Committee approval, following Caesarean section or vaginal delivery from uncomplicated singleton pregnancies. 2.3. Preparation of placental explants Villous tissue fragments (1e2 mm 3 ) were dissected from the placenta within 30 min of delivery. These were used immediately for system A activity measure- ments, or maintained in explant culture for 7 days as described previously [19]. Explant culture medium was changed daily and samples were stored at 20  C for later analysis of human chorionic gonadotrophin (hCG) using a commercially available enzyme linked immunosorbent assay kit (DRG Diagnostics, Germany). hCG secretion (mIU/ml/mg protein/h) was used as a marker of syncytiotrophoblast regeneration [19]. * Corresponding author. Tel.: þ44 161 7016962; fax: þ44 161 7016971. E-mail address: michelle.desforges@manchester.ac.uk (M. Desforges). Contents lists available at ScienceDirect Placenta journal homepage: www.elsevier.com/locate/placenta 0143-4004/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.placenta.2010.10.015 Placenta 32 (2011) 99e101