engleski

Oxidative stress, metallothioneins and environmental exposure to metals in two European brown bear populations

Levels of elements in brown bear (Ursus arctos) blood are unknown. Previously, we discovered that brown bears in Croatia have the highest tissue levels of toxic metals among hunted terrestrial wild mammals. However, associations with other related biomarkers of exposure and/or effect have not been studied. Considering that oxidative stress has been suggested as one of the pathways of toxic damage caused by metals, its biomarkers could be useful indicators of metal-related health effects. Our aim was to study biomarkers of oxidative stress (lipid peroxidation, antioxidative enzyme SOD activity) and metal exposure, (metallothionein, MT), in association with toxic metal levels in the blood of free- living brown bears from Croatia (N=8) and Poland (N=11). Metal content was measured using ICP- MS, products of lipid peroxidation (malondialdehyde, MDA) using HPLC, activity of antioxidative enzyme using spectrophotometry, and MT using differential pulse voltammetry. Median (range) mass fractions of cadmium (Cd) and mercury (Hg) in brown bear blood were 0.356 (0.110-1.34) and 7.23 (1.09-13.5) µg/kg, and showed no differences between the two populations, as well as MDA and MT. On the contrary, lead (Pb) was higher (p=0.041) in the Polish (median 145 ; range 104-192 µg/kg) compared to the Croatian (101 ; 58.9-184 µg/kg) bears, while SOD activity was lower (p=0.007) in the Polish (738 ; 21.6-2328 U/L) than in the Croatian (1428 ; 1008-2326 U/L) bears. Age, gender and season of collection had no significant influence on the measured parameters. Results present valuable contribution to toxicological studies of European brown bear and the first data describing metals and biomarkers in the blood of this species.

Biomarkers ; blood ; lipid peroxidation ; Ursus arctos

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