Fenpyroximate induced cytotoxicity and genotoxicity in Wistar rat brain and in human neuroblastoma (SH-SY5Y) cells: Involvement of oxidative stress and apoptosis

Fenpyroximate (FEN) is an acaricide used in agriculture / horticulture to control spider mites and leafhoppers. It inhibits the transport of mitochondrial electrons at the level of NADH-coenzyme Q oxidoreductase (complex I). Despite the implication of inhibition of mitochondrial complex I in neurotoxicity, especially in neurodegenerative diseases, data concerning FEN neurotoxicity remain limited. Thus, the present study was designed to investigate the toxic effect of FEN on rat brain tissue and on human neuroblastoma cells (SH-SY5Y). Rat exposure to FEN at three different doses (4.8, 9.6 and 48 mg / Kg bw) for 28 consecutive days resulted in histopathological modifications in brain tissue and a significant decrease in acetylcholinesterase activity. Further, FEN significantly enhanced lipid peroxidation and protein oxidation in rat brain and disturbed activities of antioxidant enzymes (SOD, CAT, GPx, and GST). Besides, FEN was found to induce DNA damage in a significant and dose-dependent manner in rat brain as assessed by the comet assay. To better understand FEN neurotoxic effect, we monitored our study on SH-SY5Y cells. We confirm our data found in rat brain tissue. In fact, FEN induced cell mortality in a concentration dependent manner. It over-produced intracellular ROS and lipid peroxidation and enhanced SOD and CAT activities. FEN was also found to induce DNA damage in SH-SY5Y cells. Moreover, FEN induced a loss of mitochondrial membrane potential, which confirms FEN mitochondrial impairing activity. Acridine Orange-Bromure Etidium (AO-BE) cell staining indicated that FEN enhanced the percentage of apoptotic cells in a concentration dependent manner. Further, pretreatment with a general caspases inhibitor (ZVAD-FMK), reduced significantly the FEN induced cell mortality. We also shown that FEN increased caspase 3 activity. These findings suggested, for the first time, the possibility of the involvement of mitochondrial pathway in FEN-induced cell apoptosis.