Responses to the Toxic Effects of the Neonicotinoid Thiamethoxam in Oreochromis niloticus Tissues Using Multiple Biomarkers

Abstract

Abstract The purpose of this study was to look at the toxicity of the synthetic organic insectisid thiamethoxam (TMX) at sublethal concentrations in the blood and kidney of Oreochromis niloticus. In the experiment, fish were exposed to 0, 50, 100 and 150 ppm TMX for 7 days and divided into four groups with the control group (N = 6). By the end of the experiment, fish kidney and blood collected for biochemical analysis. The hematological profile and serum levels of Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), alkaline phosphatase (ALP), albumin, blood urea nitrogen (BUN), creatinine and cortisol, serum electrolytes (potassium (K+), sodium (Na+), calcium (Ca+ 2)), uric acid, and urea were analyzed. Spectrophophotometric methods and ELISA techniques were used to assess the enzyme activities of ionoregulation (Na+/K+ ATPase, Ca+ 2 ATPase), acetylcholinesterase (AChE). In addition, the levels glutathione (GSH), thiobarbituric acid reactive substance (TBARS), DNA oxidation 8-hydroxy-2′-deoxyguanosine (8-OHdG) and protein carbonyl (PC) were detected. The results showed that parameters indicating renal function in blood samples showed a significant (p < 0.05) increase in BUN, urea, uric acid creatinine and cortisol concentrations, while albumin concentration decreased in TMX exposure compared to control group. Meanwhile, the levels of ALT, AST, and ALP were significantly (p < 0.05) dose-dependently increased in fish exposed to TMX. In parallel with the decrease in blood serum Na+, K+ and Ca+ 2 ion levels, a decrease in the activity of the ionoregulation enzymes Na+/K+ ATPase, Ca+ 2 ATPase were also observed. In the TMX effect, AChE enzyme activity, the levels of GSH and stress protein HSP70 were significantly decreased in kidney tissue depending on the dose. It was determined that lipid, protein and DNA oxidation parameters, which were examined as biomolecular parameters, caused a toxic effect of TMX with a significant increase in TBARS, PC, 8-OHdG levels, respectively (p < 0.05). As a result, in our study, it was determined by many biochemical analyzes that O. niloticus caused parallel toxic effects in kidney and blood tissue in the exposure of TMX, but this effect was more toxic with increasing dose of TMX, moreover, oxidative damage, DNA oxidation, ionregulation system also affected.