Assessment of water pollution in the Tronto river (Italy) by applying useful biomarkers in the fish model, Carassius auratus.

The Tronto River (southern Marche region of central Italy) is located in an area with neighboring industrial activities and is contaminated with domestic and industrial wastewater. Water quality data analyses revealed the presence of a mixture of low levels of heavy metals and organic compounds. The effects of long-term exposure to Tronto River water on juvenile Carassius auratus were evaluated with an integrated approach using xenoestrogens biomarkers, such as vitellogenin (VTG) and ERbeta-1 mRNA expression, and stress parameters (i.e., cortisol and glucose in the blood and glycogen in the liver). Treatment with Tronto River water did not induce VTG synthesis in fish and did not affect ERbeta-1 mRNA expression. Moreover, cortisol titers found in the plasma of fish exposed to Tronto River water were lower than those found in the control group. Regarding energy parameters, treatment with Tronto River water induced an increase in plasma glucose and a depletion of liver glycogen reserves. The effects of Tronto River water were studied in parallel with those of 4-NP and CdCl2. The 4-NP at the dose of 22 ug/L induced the synthesis of peripheral vitellogenin and increase of ERbeta-1 titers; on the contrary, CdCl2 exposure at the concentration of 22 ug/L did not induce significant changes on plasma VTG and/or hepatic ERbeta-1 levels. In addition, no significant changes in plasma cortisol levels in fish exposed to 4-NP or CdCl2 were found. Fish exposed to CdCl2 displayed liver glycogen depletion, but no significant increase in plasma glucose was observed. On the contrary, a 30-day exposure to 4-NP induced only a slight decrease of glycogen reserves without any changes in plasma glucose levels. In conclusion, our study demonstrated that long-term exposure of juvenile goldfish to the water of the Tronto River significantly affects both stress and energy parameters. There is evidence that pollutants, present in Tronto River water, were not able to induce xenoestrogenic effects but caused a functional impairment of the hypothalamum– pituitary–interrenal axis.