Gene expression kinetics of renal transporters induced by ochratoxin A in male and female F344 rats Laura Pastor a , Ariane Vettorazzi a, * , Javier Campi  on b, c , Paul Cordero b, d , Adela L  opez de Cerain a a Department of Pharmacology and Toxicology, Faculty of Pharmacy and Nutrition, University of Navarra, C/ Irunlarrea 1, 31008 Pamplona, Spain b Department of Food Science and Physiology, Faculty of Pharmacy and Nutrition, University of Navarra, C/ Irunlarrea 1, 31008 Pamplona, Spain c Current address: Making Genetics SL, Plaza CEIN 5, 31110 Noain, Spain d Current address: Institute for Liver and Digestive Health, University College London, Rowland Hill Street, London NW3 2PF, United Kingdom article info Article history: Received 2 August 2016 Received in revised form 4 October 2016 Accepted 18 October 2016 Available online 19 October 2016 Keywords: Ochratoxin A (OTA) Sex Kidney transporters Gene expression F344 rat Reference gene abstract Ochratoxin A (OTA) is a mycotoxin that contaminates foodstuffs. The most relevant concern is its high kidney carcinogenicity in male rats and its unclear mechanism of action. It has been hypothesized that variations in transport mechanisms in kidney cells may be the reason of different sex-dependent sen- sitivities towards OTA. The aim of this study was to analyze, by RT- qPCR, renal transporters expression in 15-week-old male (M) and female (F) F344 rats at basal level and after single oral OTA administration (0.50 mg/kg bw). Temporal proﬁles (24h, 48h, 72h, 96h, 1 and 2 months) were studied per sex and transporter. The reference gene for all comparisons was Ppia. At basal level, sex differences were conﬁrmed for Oatp1, Bcrp (M>F) and Oat2 (F>M). OTA tended to inhibit the expression of almost all transporters in both sexes, but clearly induced the expression of Oat2 in males. Regarding time proﬁles, the highest sex differences involved Oat (Slc22) transporters: Oat2, Oat3 and Oat5 expression showed a signiﬁcant increase in males (24h) while Oat1, Oat2 and Oat5 level decreased in females (48h). Overall, basal sex differences in F344 rats and the speciﬁc sex-dependent response to OTA of Oat2 might contribute to high kidney damage in male rats. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Ochratoxin A (OTA) is a secondary metabolite produced by different fungal species of the genera Aspergillus and Penicillium (mainly by A. ochraceus and P . verrucosum). This mycotoxin can contaminate a great variety of vegetal products, especially grains. Due to the fact that OTA is thermostable, it can enter the food chain through raw or processed products as well as through animal- origin products from livestock fed with contaminated feed (EFSA, 2006). Exposure to OTA is a worldwide phenomenon, as evi- denced by its detection in human sera in many countries (Duarte et al., 2011; M€ artlbauer et al., 2009; Soto et al., 2016). OTA is a potent nephrotoxic agent (EFSA, 2006; IARC, 1993; Lock and Hard, 2004) with clear carcinogenic effects in rodents. Unfor- tunately its mechanism of action (MoA) as a carcinogen is still unclear. In 2008, the World Health Organization (WHO, 2008) proposed 5 hypotheses as main contributors (total or partial) to the MoA of OTA: 1) Genotoxicity from direct interaction of OTA or a reactive metabolite with DNA; 2) Generation of tumors secondary Abbreviations: 18S, 18S ribosomal RNA; Abc, ATP-binding cassette; Actb, actin beta; Bcrp, breast cancer resistance protein; bw, body weight; cDNA, complemen- tary DNA (deoxyribonucleic acid); Cmax, maximum concentration; C t , threshold cycle; CV, coefﬁcient of variation; EFSA, European Food Safety Authority; F, female; F344, Fisher 344; Gapdh, glyceraldehyde-3-phosphate dehydrogenase; IARC, In- ternational Agency for Research on Cancer; M, male; mRNA, messenger RNA (ribonucleic acid); MIQE, Minimum Information for Publication of Quantitative Real-Time PCR Experiments; MoA, mechanism of action; Mrp, multidrug resistance protein; NaHCO 3 , sodium hydrogen carbonate; NTP, National Toxicology Program; Oat, organic anion transporter; Oatp, organic anion transporter polypeptide; OTA, ochratoxin A; qPCR, quantitative polymerase chain reaction; Pept, oligopeptide transporter; Ppia, peptidylprolyl isomerase A (cyclophilin A); Q, relative quantiﬁ- cation level; RT, reverse transcription; RT-qPCR, reverse transcription quantitative real-time polymerase chain reaction; SD, standard deviation; Slc, solute carrier; SV, stability value; Taq, Thermus aquaticus; Ubc, ubiquitin C; WHO, World Health Organization. * Corresponding author. C/ Irunlarrea 1, 31008, Centro de Investigaci on Farm- acobiología Aplicada (CIFA), Universidad de Navarra, Pamplona, Spain. E-mail addresses: lpcastro@alumni.unav.es (L. Pastor), avettora@unav.es (A. Vettorazzi), jcampion@making-genetics.eu (J. Campi on), paul.sanchez@ucl.ac. uk (P. Cordero), acerain@unav.es (A. L opez de Cerain). Contents lists available at ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox http://dx.doi.org/10.1016/j.fct.2016.10.019 0278-6915/© 2016 Elsevier Ltd. All rights reserved. Food and Chemical Toxicology 98 (2016) 169e178