24 Poster Abstracts / Toxicology 262 (2009) 8–26 Table 1 Twenty-four-hour results. Mouse Rat R.O.A IP PO IP PO Compound FS TPA FS TPA FS TPA FS TPA ALT (X ULN) 103.3 5.518 0.720 0.478 0.48. 0.611 0.376 0.649 (21.56) * (2.35) ** (0.89) (0.13) (0.28) (0.23) (0.06) (0.21) Cumulative AUC 4,073.7 5,856.7 2,089.6 3,993.0 4,921.0 (0.23) 1,040.5 2,302.3 Plasma (mg h/ml) (699.2) (820.9) (738.2) (468.6) (1150.1) (1124.7) (173.9) (580.3) Cumulative AUC 2,764.6 4,868.0 560.9 1,272.4 1,279.8 4,042.7 1,656.5 526.3 Liver (mg h/ml) (599.9) (925.5) (255.8) (378.0) (114.3) (647.2) (916.2) (129.1) ALT values; ULN—upper limit of Normal (Boehm et al., 2007): Mean (SDev) n =4; ROA—route of administration; AUC value: Mean (SDev) n = 4. * P <0.001 when compared to Mouse TPA IP. ** P < 0.05 when compared to Mouse TPA PO. Reference Vandeputte, C., Guizon, I., Genestie-Denis, I., Vannier, B., Lorenzon, G., 1994. Cell Biol Toxicol 10 (5–6), 415–421. Williams, D.P., Antoine, D.J., Butler, P.J., Jones, R., Randle, L., Payne, A., Howard, M., Gardner, I., Blagg, J., Park, B.K., 2007. J Pharmacol Exp Ther 322 (3), 1208–1220. Boehm, O., Zur, B., Koch, A., Tran, N., Freyenhagen, R., Hartmann, M., Zacharowski, K., 2007. Clinical chemistry reference database for Wistar rats and C57/BL6 mice. Biol Chem 388 (5), 547–554. doi:10.1016/j.tox.2009.04.029 P36 Characterisation of pesticide transport in neural cells Katherine Betteley a , Amy S. Windass a , Elaine Mutch b , Colin D.A. Brown a , Faith M. Williams b,∗ a Institute for Cell & Molecular Biosciences, United Kingdom b Institute for Research in Environment and Sustainability and Medical Toxicology Centre, Newcastle University, Newcastle-upon Tyne, United Kingdom E-mail address: f.m.williams@ncl.ac.uk (F.M. Williams). The central nervous system (CNS) is well protected from sys- temic exposure to drugs mainly by the ability of the efflux transport proteins in the endothelial cells that form the blood brain barrier to efficiently limit exposure. However, comparatively little is known about the role of transporters in limiting access of pesticides with neurotoxic potential. The aim of this study was to understand the importance of transporters in the distribution of pesticides within the CNS. To achieve this we firstly compared the expression of trans- port proteins at the mRNA level from cDNA derived from human Substantia nigra, a site particularly susceptible to xenobiotic dam- age, with SH-SY5Y human neuroblastoma cells which were used as a model neuronal cell line. The expression of a range of transport proteins was examined at the mRNA level using a series of gene- specific primers for the transporters. Secondly, we investigated the functional role of uptake transporters in the cellular accumulation of a range of pesticides in the Xenopus oocyte expression system. The ability of pesticides to cis-inhibit prototypic substrate uptake by cloned transporters was determined. Thirdly, we investigated the interaction of pesticides (50 M) with the efflux transporter MDR1 in SH-SY5Y cells by the Hoechst 33342 dye efflux assay. Human substantia nigra and human SH-SY5Y cells in culture expressed a common range of transporters at the mRNA level including OAT3, OAT4, OCT2, OCTN2, OATP-B, OATP-D, OATP-E, NET, DAT, SERT and the ABC-transporter MDR1. There was no evidence of expression of BCRP or MRP2 in substantia nigra at the mRNA level. In the Xenopus oocyte system, lindane, dieldrin and heptachlor (50 M) interacted with OCTN2-mediated MPP+ uptake which was inhibited (P < 0.01 compared to control) in the presence of these pesticides. Chlorpyrifos, diazinon, dichlorvos, permethrin and deltamethrin (all at 50 M) had no effect. The pattern of inhibition of MPP+ uptake into SH-SY5Y cells matched that of MPP+ uptake by OCTN2 expressed in Xenopus oocytes. There was no interaction between lindane, dield- rin, heptachlor, chlorpyrifos, diazinon, dichlorvos, permethrin or deltamethrin (50 M) and OAT3, OAT4, OCT2, OATP-B, OATP-D, OATP-E, NET, DAT or SERT when expressed in Xenopus oocytes. In human SH-SY5Y cells dichlorvos, chlorpyrifos, diazinon, deltamethrin and dieldrin (50 M) inhibited MDR1-mediated Hoechst 33342 dye efflux (P <0.01, ANOVA). Dose–response curves for deltamethrin and diazinon showed inhibition of uptake with apparent Km values for MDR1 of 23.5 ± 3.4 M for deltamethrin and 17.6 ± 3.2 M for diazinon compared with 2.5 ± 0.3 M for cyclosporin (known MDR1 substrate). These data indicate that SH-SY5Y cells may be a good cell model for studying uptake and efflux in human substantia nigra. The efflux pump MDR1 may play an important role in protecting cells from exposure to a range of pesticides of differing structures which enter the cell by diffusion with minor contribution from active influx by OCTN2. doi:10.1016/j.tox.2009.04.030 P37 Sex differences in formic aciduria in Fischer 344 (F-344) rats and dose response in male F-344 rats exposed orally to trichloroethy- lene Noreen Yaqoob ∗ , Nicola Dempster, Celia J. Reed, Edward A. Lock School of Pharmacy and Biomolecular Science, Liverpool John Moores University, L3 3AF, United Kingdom E-mail address: N.Yaqoob@2007.ljmu.ac.uk (N. Yaqoob). 1,1,2-Trichloroethylene (TCE) is an industrial solvent, its use hav- ing resulted in contamination of air and ground water, worldwide. TCE has been shown to cause, at high doses, formic aciduria in male F-344 rats (Green et al., 1998). The aim of this study was to examine the dose–response relationship for TCE-induced formic aciduria in male F-344 rats and examine any sex-difference in this response. Male F-344 (200–250 g) and female F-344 (155–200 g) rats, in two separate studies per sex, were placed in metabolism cages with food and water available ad libitum. After 24 h of acclimatization (Day 0) the rats were dosed orally with 62.5, 125, 250, 500 or 1000 mg/kg TCE in corn oil (5ml/kg) for three consecutive days (Days 1–3). In two separate studies, male F-344 rats were dosed orally with 2 (n =3); 4 (n =2); 8 (n =3); 16 (n =6) or 31 (n = 6) mg/kg/day TCE. Urine was collected overnight into 10% sodium azide (0.1ml) and analysed for formic acid using 300 MHz Nuclear Magnetic Reso- nance (NMR) spectrometer. Samples for NMR were prepared in