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Relationships between POPs, biometrics and circulating steroids in male polar bears (Ursus maritimus) from Svalbard. | LitMetric

AI Article Synopsis

  • - The study investigated how persistent organic pollutants (POPs) and various biological factors influence steroid hormone levels in male polar bears from Svalbard, Norway, analyzing 23 individuals for hormone and POP concentrations using advanced gas chromatography techniques.
  • - It found that males synthesized sex steroids mainly through the Δ-4 pathway, with significant differences in androgen to estrogen ratios based on sexual maturity, showing adult males had much higher ratios than subadult males.
  • - The research also revealed correlations where testosterone levels were positively associated with body condition, while dehydrotestosterone levels negatively correlated with POPs, suggesting these environmental contaminants and physiological factors could impact the polar bears' hormonal functions and reproductive health.

Article Abstract

The aim of this study was to determine the effects of persistent organic pollutants (POPs) and biometric variables on circulating levels of steroid hormones (androgens, estrogens and progestagens) in male polar bears (Ursus maritimus) from Svalbard, Norway (n = 23). Levels of pregnenolone (PRE), progesterone (PRO), androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in polar bear serum by gas chromatography tandem mass spectrometry (GC-MS/MS), while POPs were measured in plasma. Subsequently, associations between hormone concentrations (9 steroids), POPs (21 polychlorinated biphenyls (PCBs), 8 OH-PCBs, 8 organochlorine pesticides (OCPs) and OCP metabolites, and 2 polybrominated diphenyl ethers (PBDEs)) and biological variables (age, head length, body mass, girth, body condition index), capture date, location (latitude and longitude), lipid content and cholesterol levels were examined using principal component analysis (PCA) and orthogonal projections to latent structures (OPLS) modelling. Average concentrations of androgens, estrogens and progestagens were in the range of 0.57-83.7 (0.57-12.4 for subadults, 1.02-83.7 for adults), 0.09-2.69 and 0.57-2.44 nmol/L, respectively. The steroid profiles suggest that sex steroids were mainly synthesized through the Δ-4 pathway in male polar bears. The ratio between androgens and estrogens significantly depended on sexual maturity with androgen/estrogen ratios being approximately 60 times higher in adult males than in subadult males. PCA plots and OPLS models indicated that TS was positively related to biometrics, such as body condition index in male polar bears. A negative relationship was also observed between POPs and DHT. Consequently, POPs and body condition may potentially affect the endocrinological function of steroids, including development of reproductive tissues and sex organs and the general condition of male polar bears.

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Source
http://dx.doi.org/10.1016/j.envpol.2017.06.095DOI Listing

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