Malathion-induced Biochemical and Molecular Changes in the Brain of Danio rerio as Biomarkers of Oxidative Stress Damage

Malathion is the most widely used organophosphorus pesticide in freshwater ecosystems around the world. In Danio rerio brain specimens, the effects of MAL exposure on oxidative stress stimulation and acetylcholinsterase, as well as gene expression and histology, were investigated. Antioxidant enzyme activities (superoxides dismutase and catalase) and AChE levels changed widely in brain. The mRNA levels of genes encoding antioxidant enzymes such as Cu/Zn–SOD, Mn–SOD, and COX-17 did not increase when zebrafish were exposed to varied levels of MAL for 5 and 25 days. CAT, GPx, CYP1A, and AChE transcription were all enhanced significantly following exposure to MAL levels (P<0.05). Variations in the brain's antioxidant enzyme did not match mRNA induction patterns. Furthermore, with higher exposure time and dose, pathological changes included more severe tissue harm. These alterations are common cellular responses for pesticides and are expected to be an important signal in ecotoxicology studies. Given our findings, the Danio rerio can be used as a model organism for the further research of pesticide effects on the CNS and the various mechanisms involved.