Abstract
Diazinon (DZN) is a promising broad-spectrum organophosphorus insecticide. There is no evidence to support the hypothesis that DZN alters cytokine gene expression and that these modifications have an immediate impact on the histopathology, blood chemistry and oxidative stress in Nile tilapia (Oreochromis niloticus). Therefore, 225 fish were divided into one control group and four treatment groups (45 fish/group; 3 replicates/group; 15 fish/ replicate). Fish in the control group were supplied with water free of DZN. Fish in the treatment groups (T1-T4) were intoxicated with DZN at 0.28 mg/L for 1, 2, 3 and 4 weeks, respectively. Activities of AST and ALT and the concentrations of uric acid, creatinine and MDA increased significantly in the serum of DZN treated fish compared to the control. Protein parameters, GSH concentration and activities of antioxidant enzymes decreased significantly in the serum of DZN treated fish. DZN intoxication induced an elevation in MDA concentration and a reduction in GSH concentration and activities of CAT and GPX enzymes in the liver and kidney tissues of DZN treated fish. DZN intoxication induced a significant elevation in gene expression levels of TNF-alpha, IL-8, IL-1 beta accompanied by a significant reduction in IL-10 gene expression levels in the liver and kidney tissues of DZN treated fish. The histopathological changes in DZN intoxicated fish were in the form of necrosis and degeneration of hepatocytes as well as desquamation and vacuolation of renal epithelium. Conclusively, DZN intoxicated Nile Tilapia exhibited oxidative damage, reduced cytokine gene expression and hepatorenal necrosis, which was intensified with the length of fish exposure to DZN.