Molecular markers of cytotoxicity induced with copper-contained pesticides

Abstract

The applying copper sulphate is a cheap, however it leads to global the environment contamination. Especially, the contamination of the water sources is crucial for fish harvesting and farming. The copper contamination in some areas are caused by decades. The impact of copper ions is dependent on the inhibition of invasive aquatic plants, many microorganisms and protozoa. The family of copper-contained chemicals is frequently used as algaecides in swimming pools. Despite the copper ions are well known as a high toxic for fish in freshwater ponds, the copper sulphate remains one of the prevalent pesticides in fish farming everywhere. High cytotoxicity and accumulation of the copper ions in the sediments require studying and calculation of the optimal dosage to use it as an antiseptic agent that should prevent the detrimental effect in various tissue types of aquatic organisms. The main depicted mechanism, which is associated with cytotoxicity is the generation of oxidative stress. Neural tissue cells are extremely susceptible to oxidative damages. Neural damaging is important cause of the CNS disfunction as well as is the critic to the organism vitality. Glial cells maintain the structure and many vital functions of neuronal cells. Glial fibrillary acidic protein (GFAP), transcriptional nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) and poly(ADP-ribose) polymerase (PARP) are critic regulators in a cell response to the environment toxicity. Based on this fact, it could be applied as the boimarkers of heavy metal toxicity. In presented study, we investigated the effects of copper ions on PARP, NF-kB, and GFAP expression in the rainbow trout (Oncorhynchus mykiss) brain tissue. For 96 hours the fishes were exposed to the copper sulphate sublethal concentrations 380 µg/L, estimated as 1/4 of the LC50 value. Western blot analysis of GFAP, NF-kB and PARP was used to assess further effects in the brain tissue. The modulatory effect of copper ions on the expression of GFAP was detected in fish brain. Reciprocal changes were observed in respect with 24 hours exposure in compare to both 48 hours and 96 hours treatment. Obtained results demonstrated meaningful disturbance in the expression of transcriptional factor NF-kB in the brain of fish group exposed to copper in compare to control group. Furthermore, the time-depended effect in a range 24 – 96 hours was detected. However, the short time exposure to copper ions initiated no effect in fish group treated 24 hours while in compare to both 48 hours and 96 hours treatment. The similar changes of PARP content in the brain of fish were determined as well. It deserves to be mentioned that all of aforementioned changes of GFAP, NF-kB and PARP expression were accompanied by increasing in reactive oxygen species content. Thus, copper ions cytotoxic effect could be initiated with oxidative injury in a brain tissue. On the other hand, the observed effect of copper in the fish brain evidences the unspecific toxicity of this ion in brain tissue cells. The results showed that copper ions could induce astroglial response accompanied by modulations of NF-kB and PARP-1 expression. Obtained in presented study data suggest that copper sulphate has significant effect on astrogliosis and DNA damage in the fish brain.