engleski

Fumonisin B1 activates reactive oxygen species production

Fumonisin B1 (FB1) is a mycotoxin, produced by Fusarium verticiloides mould that contaminates maize world-wide. Its potential health hazard as a natural toxin is well documented in domestic and experimental animals. Exposure to FB1 is linked with higher incidence of oesophageal cancer, primary liver cancer and neural tube defect in regions of South Africa, Central America and China where maize is staple food. It is proposed that oxidative stress is involved in FB1 toxicity. The aim of this study was to further explore mechanism and sources of reactive oxygen species (ROS) production upon FB1 exposure (0.5 µM, 5 µM and 50 µM) on human neuroblastoma (SH-SY5Y) cells. Dihydroethidium (HEt) an indicator of production of ROS (mostly superoxide) in cytosol and MitoSOX an indicator of ROS production in mitochondria were used. ROS production was monitored on epifluorescence inverted microscope ; all imaging data were collected and analysed using software from Andor, and statistical difference of results were tested using Statistica 8.0 program. FB1 significantly increased the rate of ROS production already with lowest dose (124.9±5.0 ; n=4 experiments, p<0.05), but the effect was not dose-dependent. Inhibition of NADPH oxidase with diphenylene iodonium (DPI) and inhibition of glutathione with monochlorobiamine (MCB) had no effect on the ability of FB1 to increase the rate of ROS production. However, the uncoupler of the mitochondrial respiratory chain, carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (FCCP) completely blocked the ROS production stimulated with FB1. The rate of ROS production after inhibition with FCCP was even lower compared to the basic rate of ROS in control cells from 81.7±2.8 for 0.5 µM to 77.0±5.4 for 50µM concentration (n=4 experiments ; p<0.05). In MitoSOX experiments, all doses of FB1 increased MitoSOX florescence, but only the lowest concentration had significant effect (125.3±3.2% ; n=3 experiments ; p<0.05). Taken together our results suggest a mitochondrial origin of FB1-induced ROS production and point to a specific role of the mitochondrial respiratory chain in FB1 response.

fumonisin B1; mycotoxins; oxidative stres; reactive oxygen species

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