Selenium and mercury concentrations, Se:Hg molar ratios and their effect on the antioxidant system in wild mammals

The aim of this study was to a) evaluate the concentration of Se and Hg and their relationship in the tissues of 4 species of wild mammals, including Se:Hg molar ratios, and b) evaluate the effect of the analysed elements and their mutual proportions expressed as Se:Hg molar ratio, on the antioxidant system in the tissues of the tested animals. The study was performed on 31 animals belonging to four species: wild boar, red fox, roe deer, brown hare. Determination of Hg in liver, kidney and muscle of animals was performed using an AMA 254 mercury analyser. Total Se concentrations were determined using the spectrofluorometric method. In omnivores demonstrated higher Se concentrations in all analysed organs compared to the herbivores. The highest concentration of Hg was found in the kidneys of the tested animals, and the lowest in the muscles. High and moderate correlation between Se and Hg was observed in the liver of omnivorous, while in herbivores this correlation was weak. In all analysed samples, the Se:Hg molar ratios were above 1 (min: liver 5.9, max: kidney 110). Generally, the highest Se:Hg ratio values were found in kidney and the lowest in liver of tested animals. No significant correlation was found between GPx, GST and SOD activity and Se or Hg concentration in analysed organs. But it was observed that Se:Hg molar was negatively correlated with CAT activity in the most samples. The obtained results may suggest that omnivorous animals demonstrate greater Hg sequestration in the liver than herbivores, which has been proposed as one of the mechanisms of Se antagonistic action towards Hg. The ratio between Se and Hg, rather than the concentration of these elements in organs, affected the antioxidant status in the animal organism, specifically the CAT activity.