Organic insecticide spinosad causes in vivo oxidative effects in the brain of Oreochromis niloticus

Spinosad is an organic insecticide derived from a naturally occurring soil bacterium and is used in organic farming worldwide. The aim of this study was to evaluate in vivo toxic effects of spinosad in the brain of Oreochromis niloticus as a model organism. The fish were exposed to sublethal spinosad concentrations (25, 50, 75 mg L(-1) ) for 24-48-72 h to determine tGSH, GSH, GSSG, and TBARS contents, GSH/GSSG ratio, and GPx, GR, GST enzymes activities using spectrophotometrical methods, and HSP70 content by an ELISA technique. Spinosad caused elevations in the contents of tGSH, GSH, GSSG, HSP70, and reductions in the ratio of GSH/GSSG and GPx activity and an induction in the GR activity. The results indicated that spinosad had oxidative effects in the brain tissue by altering the parameters in GSH-related antioxidant system and HSP70. It was also suggested that spinosad-induced free-radicals were eliminated by GSH-related antioxidant system in the brain of Oreochromis niloticus.