Oxidative stress, glutathione, and gene expression as key indicators in SH-SY5Y cells exposed to zearalenone metabolites and beauvericin.

The co-presence of mycotoxins from fungi of the genus Fusarium is a common fact in raw food and food products, as trace levels of them or their metabolites can be detected, unless safety practices during manufacturing are carried out. Zearalenone (ZEA), its metabolites α-zearalenol (α-ZEL) and ß-zearalenol (ß-ZEL) and, beauvericin (BEA) are co/present in cereals, fruits or their products which is a mixture that consumer are exposed and never evaluated in neuronal cells. In this study the role of oxidative stress and intracellular defense systems was assessed by evaluating reactive oxygen species (ROS) generation and glutathione (GSH) ratio activity in a human neuroblastoma cell line, SH-SY5Y cells, treated individually and combined with α-ZEL, ß-ZEL and BEA. It was further examined the expression of genes involved in cell apoptosis (CASP3, BAX, BCL2) and receptors of (endogenous or exogenous) estrogens (ERß and GPER1), by RT-PCR in those same conditions. These results demonstrated elevated ROS levels in combinations where α-ZEL was involved (2.8- to 8-fold compared to control); however, no significant difference in ROS levels were detected when single mycotoxin was tested. Also, the results revealed a significant increase in GSH/GSSG ratio at all concentrations after 24 h. Expression levels of CASP3 and BAX were up regulated by α-ZEL while CASP3 and BCL2 were down regulated by ß-ZEL, revealing how ZEA´s metabolites can induce the expression of cell apoptosis genes. However, BEA down-regulated the expression of BCL2. Moreover, ß-ZEL + BEA was the only combination treatment which was able to down regulate the levels of cell apoptosis gene expression. Relying to our findings, α-ZEL, ß-ZEL and BEA, induce injury in SH-SY5Y cells elevating oxidative stress levels, disturbing the antioxidant activity role of glutathione system and finally, causing disorder in the expressions and activities of the related apoptotic cell death genes.