Biomarkers of the cholinergic and dopaminergic signaling pathways in Arctic beluga whales (Delphinapterus leucas): relationship to methylmercury and selenium

There are increasing concerns about potential neurotoxicity of chronic methylmercury (MeHg) exposure in Arctic wildlife and human populations. The relationships between mercury (Hg), MeHg, inorganic Hg (iHg), and selenium (Se) exposure, and neurochemical and molecular biomarkers in beluga whales (De...

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Bibliographic Details
Published in:Arctic Science
Main Authors: Sonja K. Ostertag, Hing Man Chan
Format: Article in Journal/Newspaper
Language:English
French
Published: Canadian Science Publishing 2018
Subjects:
mercury
biomarker
neurochemical
neurotoxicity
inuit
Environmental sciences
GE1-350
Environmental engineering
TA170-171
Arctic
Beaufort Sea
Beluga
Beluga*
Delphinapterus leucas
Online Access:https://doi.org/10.1139/as-2017-0033
https://doaj.org/article/b58cc8b184334cca8e7df29b2733753e
Description
Summary:There are increasing concerns about potential neurotoxicity of chronic methylmercury (MeHg) exposure in Arctic wildlife and human populations. The relationships between mercury (Hg), MeHg, inorganic Hg (iHg), and selenium (Se) exposure, and neurochemical and molecular biomarkers in beluga whales (Delphinapterus leucas (Pallas, 1776)) were characterized. Samples were collected in 2008 (n = 20) and 2010 (n = 15) in the Canadian Arctic from hunter-harvested beluga whales. Total Hg concentrations in the temporal cortex and cerebellum were 21.0 ± 22.6 mg kg−1 dry weight (dw) and 14.9 ± 18.9 mg kg−1 dw, respectively. Monoamine oxidase (MAO) activity was predicted by MeHg and the molar ratio of total Hg to Se (Hg:Se, p < 0.05); MAO-A mRNA transcription levels were predicted by iHg and Se (p < 0.05). Muscarinic AChR binding was predicted by MeHg (p < 0.05) and Hg:Se molar ratio (p < 0.05), and mRNA transcription levels of mAChR m1 was predicted by the Hg:Se molar ratio (p < 0.05). These results suggest that the cholinergic and dopaminergic signaling pathway in Eastern Beaufort Sea beluga whales may be sensitive to MeHg exposure. The response of beluga whales to MeHg exposure at a physiological and population level remains to be elucidated.

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