Comparison of oxidative stress parameters between rats exposed to methylmercury in aqueous solution and fish contaminated with the metal

Author(s)

Denise Grotto

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2011-05-04

Examining board members

Fernando Barbosa Junior; Daniel Junqueira Dorta; Wilma de Grava Kempinas; Sergio Koifman; Gustavo Henrique de Almeida Teixeira

• Advisor: Fernando Barbosa Junior

Abstract

The toxic effects due the consumption of fish contaminated with methylmercury (MeHg) have been widely discussed in Brazil, especially in Amazon region, where studies have shown confound results. Nutritional factors associated with MeHg exposure or the form of MeHg in fish could be changing MeHg toxicity. Thus, rats were subchronically exposed to MeHg in solution, selenium (Se) and fish oil, or rats were fed with a diet containing MeHg-contaminated fish. Oxidative stress biomarkers, presence of inflammation, genotoxicity, systolic blood pressure, nitric oxide (NO) levels and total mercury (Hg) and Se in different tissues were determined. Rats exposed to MeHg in solution showed endogenous antioxidants significantly reduced, increase of lipid peroxidation, hypertension, tissue inflammation, DNA damage and decrease of NO levels. MeHg+Se association presented antioxidant protection and antigenotoxic effetc, but it was not able to protect the inflammation induced by MeHg. Surprisingly, rats treated only with Se also showed increase in systolic blood pressure. MeHg+fish oil association presented a significant antiinflammatory and antigenotoxic effects and antihypertensive action; however it was not observed antioxidant capacity of fish oil. Hg absorption in different tissues was not modified by Se or fish oil treatments. On the other hand, rats fed with diet containing MeHg-contaminated fish presented few alterations in biomarkers. A lipid peroxidation biomarker showed significantly increased in rats fed with MeHgcontaminated fish as well as induction of DNA damage. From the 11th week, a hypertension was observed and NO levels did not change. In conclusion, it was observed that MeHg solution was able to induce oxidative effects, inflammation, genotoxicity and hypertension, and MeHg linked in fish induced considerable but mild effects. The chemical form that MeHg is present in fish combined with nutrients from fish, as Se and polyunsaturated fatty acids could contribute to reducing toxic effects of MeHg. (AU)

• FAPESP's process: 07/05221-4 - Evaluation of oxidative stress and nitric oxide availability in rats exposed to fish contaminated to MeHg
• Grantee: Denise Grotto
• Support Opportunities: Scholarships in Brazil - Doctorate