Lipid oxidation and metabolism in relation to contaminants in polar bears from the Canadian high arctic and Hudson Bay.

Environmental contaminants, particularly persistent organic pollutants (POPs) and mercury, pose significant threats to wildlife health, with complex interactions between contaminants and biological processes that are challenging to assess in field studies. This research investigates the oxylipin metabolome in liver samples from polar bears (Ursus maritimus) in two geographically distinct subpopulations from Western Hudson Bay (WHB) and Baffin Bay (BB), Canada, with the aim of elucidating the impact of environmental contaminants on metabolic and inflammatory pathways. Oxylipins, bioactive lipid metabolites derived from polyunsaturated fatty acids, regulate critical biological processes such as inflammation and vascular tone. We identified significant differences in oxylipin levels between the two subpopulations, with WHB bears showing higher concentrations of several key metabolites, including Prostaglandin E2 (PGE2) and 5-iPF2a-VI, an isoprostane, both associated with inflammation and oxidative stress. Contaminant analysis revealed elevated levels of specific POPs, including polybrominated diphenyl ether (PBDEs), in WHB polar bears. These results suggest a potential link between contaminant exposure and altered oxylipin metabolism, which may contribute to liver dysfunction and inflammation. Multivariate analysis also revealed correlations between contaminants and metabolic pathways related to liver disease, including arginine biosynthesis and alanine, aspartate and glutamate metabolism. Our findings underscore the importance of considering the interplay between environmental contaminants and lipid signaling in wildlife health, particularly in the context of Arctic ecosystems, and highlight the need for further research to explore the long-term impacts of these exposures on polar bear populations and other wildlife species in the Arctic.