Molecular and cellular pharmacology Oxidative stress induced by tert-butylhydroperoxide interferes with the placental transport of glucose: In vitro studies with BeWo cells João R. Araújo 1 , Ana C. Pereira 1 , Ana Correia-Branco, Elisa Keating, Fátima Martel n Q1 Department of Biochemistry (U38-FCT), Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal article info Article history: Received 22 February 2013 Received in revised form 10 October 2013 Accepted 16 October 2013 Keywords: Glucose Oxidative stress Placenta Transport abstract Increased oxidative stress is implicated in the onset and progression of prevalent pregnancy disorders (e.g. gestational diabetes and fetal growth restriction), and in programming the fetus to develop metabolic diseases later in life. Since the molecular mechanisms underlying these effects of oxidative stress are largely unexplored, we aimed to investigate if the placental transport of glucose – the main energetic substrate for the fetus and placenta – is altered by oxidative stress. In a human syncytio- trophoblast (STB) cell model, the BeWo cell line, oxidative stress was induced by treatment with 100 mM tert-butylhydroperoxide (tert-BOOH) for 24 h. Tert-BOOH decreased the steady-state intracellular accumulation (A max ) of [ 3 H]2-deoxyglucose ([ 3 H]DG) mediated by both facilitative (GLUT) and non- facilitative (non-GLUT) glucose transporters. These effects were not associated with a change in the mRNA expression level of GLUT1, the major placental glucose transporter. Also, they seemed to be independent from phosphoinositide 3-kinase and protein kinase C signaling pathways and were unchanged either by inhibitors of free radical-generating enzymes or by free radical scavengers. In contrast, the dietary polyphenols quercetin, epigallocatechin-3-gallate and resveratrol completely reversed the inhibitory effect of tert-BOOH upon [ 3 H]DG accumulation through a specific effect on GLUT-mediated transport. Finally, tert-BOOH induced an increase in the transepithelial permeability to [ 3 H]DG in the apical-to-basal direction, apparently related to an increase in its paracellular transport. In conclusion, tert-BOOH-induced oxidative stress reduces STB accumulation of glucose associated with an increase in its transepithelial permeability. This effect may contribute to the deleterious consequences of pregnancy disorders associated with oxidative stress. & 2013 Published by Elsevier B.V. 1. Introduction One of the major functions of the placenta is to mediate the transport of nutrients from the mother to the fetus over the course of gestation. This function depends on the activity of specific transporters present at the apical (maternal-facing) and basal (fetal-facing) membranes of the syncytiotrophoblast (STB) epithe- lium (Jansson et al., 2009). Glucose is the primary substrate for energy metabolism in the feto-placental unit, and together with amino acids, it constitutes the primary stimuli for fetal secretion of the growth-promoting hormone insulin (Jansson et al., 2009). Since fetal glucose produc- tion is minimal (Magnusson et al., 2004), placental transport constitutes the primary source of glucose to the fetus (Baumann et al., 2002; Carter, 2012). Accordingly, alterations in glucose transport and metabolism at the STB level are strongly associated with aberrant fetal growth (Baumann et al., 2002; Desoye et al., 2011; Illsley, 2000; Magnusson et al., 2004), which increases the risk of perinatal complications and predispose the newborn to develop cardiovascular and metabolic diseases later in life (Jansson et al., 2009; Vo and Hardy, 2012). Placental transport of glucose occurs mainly through facilitative glucose transporters (GLUT). At least five different GLUT isoforms are expressed in the human STB: GLUT1, 3, 4, 9 and 12. However, the primary isoform responsible for glucose transport across the apical and basal membranes of the STB in term pregnancy is GLUT1 (Baumann et al., 2002; Carter, 2012; Jansson et al., 2009). GLUT1 distribution in the STB is asymmetric, with a greater expression and activity in the apical membrane, which assures that glucose is transported down its concentration gradient from maternal to fetal circulation (Baumann et al., 2002; Carter, 2012). An increasing amount of evidence implicates oxidative stress in the pathophysiology of prevalent pregnancy complications such as miscarriage (Myatt and Cui, 2004), preeclampsia (Siddiqui et al., 2010), fetal growth restriction (Son et al., 2004; Takagi et al., 2004) and gestational diabetes (Coughlan et al., 2004; Lappas et al., 2011; Peuchant et al., 2004). Moreover, increased oxidative stress at the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ejphar European Journal of Pharmacology 0014-2999/$ - see front matter & 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.ejphar.2013.10.023 n Corresponding author. Tel.: þ351 22 0426654; fax: þ351 22 5513624. E-mail address: fmartel@med.up.pt (F. Martel). 1 João R. Araújo and Ana C. Pereira equally contributed to the work. Please cite this article as: Araújo, J.R., et al., Oxidative stress induced by tert-butylhydroperoxide interferes with the placental transport of glucose: In vitro studies with BeWo cells. Eur J Pharmacol (2013), http://dx.doi.org/10.1016/j.ejphar.2013.10.023i European Journal of Pharmacology ∎ (∎∎∎∎) ∎∎∎–∎∎∎