title: Effects of mercury on neurochemical receptors in wild river otters (Lontra canadensis).
abstract: Fish-eating wildlife, such as river otters (Lontra canadensis), accumulate mercury (Hg) at concentrations known to impair animal behavior, but few studies have explored the underlying biochemical changes that precede clinical neurotoxicity. The objective of this study was to determine if Hg exposure can be related to concentrations of neurochemical receptors in river otters. River otter carcasses (n = 66) were collected in Ontario and Nova Scotia (Canada) by local trappers in 2002-2004. Concentrations of Hg (total and organic) were measured in the cerebral cortex and cerebellum. Saturation binding curves for the cholinergic muscarinic acetylcholine (mACh) receptor and dopamine-2 (D2) receptor were completed for each animal to calculate receptor density (Bmax) and ligand affinity (Kd). Negative correlations were found between concentrations of Hg and mACh receptor Bmax (r(total) Hg = -0.458, r(inorganic) Hg = -0.454, r(organic) Hg = -0.443) in the cerebral cortex. A negative correlation was also found between concentrations of total Hg and D2 receptor Bmax (r = -0.292) in the cerebral cortex. These results suggest that neurochemical receptors may prove useful as novel biomarkers of Hg exposure and neurotoxic effects in wildlife. Given the importance of cholinergic and dopaminergic systems in animal physiology, the ecological implications of these changes need to be investigated.
authors.affiliation: Department of Natural Resource Sciences, Centerfor Indigenous Peoples' Nutrition and Environment (CINE), and School of Dietetics and Human Nutrition, McGill University, Saint Anne de Bellevue, Quebec, Canada H9X 3V9.
authors.forename: Niladri
authors.initials: N
authors.lastname: Basu
authors.forename: Anton
authors.initials: A
authors.lastname: Scheuhammer
authors.forename: Nicole
authors.initials: N
authors.lastname: Grochowina
authors.forename: Kate
authors.initials: K
authors.lastname: Klenavic
authors.forename: Douglas
authors.initials: D
authors.lastname: Evans
authors.forename: Mike
authors.initials: M
authors.lastname: O'Brien
authors.forename: Hing Man
authors.initials: HM
authors.lastname: Chan
mesh_terms: D000818:Animals; D015415:Biomarkers; D002531:Cerebellum / Q000737:chemistry / Q000378:metabolism; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism; D004032:Diet; D018492:Dopamine Antagonists / Q000494:pharmacology; D004784:Environmental Monitoring; D005399:Fishes; D008628:Mercury / Q000032:analysis / Q000378:metabolism*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009674:Nova Scotia; D009864:Ontario; D010041:Otters / Q000378:metabolism*; D011813:Quinuclidinyl Benzilate / Q000494:pharmacology; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013134:Spiperone / Q000494:pharmacology; D014316:Tritium; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D018492:Dopamine Antagonists; D018727:Muscarinic Antagonists; D017448:Receptors, Dopamine D2; D011976:Receptors, Muscarinic; D014874:Water Pollutants, Chemical; D014316:Tritium; D013134:Spiperone; D011813:Quinuclidinyl Benzilate; D008628:Mercury