Effects of mercury on neurochemical receptor‐binding characteristics in wild mink

Abstract

Piscivorous wildlife, such as mink (Mustela vison), routinely are exposed to mercury (Hg) in their natural environment at levels that may cause adverse behavioral outcomes. The purpose of this study was to determine if a correlation exists between neurochemical receptors and concentrations of Hg in the brains of wild mink. Specifically, receptor-binding assays were conducted to characterize the muscarinic cholinergic (mACh) and dopaminergic-2 (D2) systems in brain tissues collected from mink trapped in the Yukon Territory, Ontario, and Nova Scotia (Canada), and values were correlated with total Hg and methyl Hg (MeHg) concentrations in the brains. A significant correlation was found between Hg (total Hg and MeHg) and mACh receptor density (r = 0.546; r = 0.596, respectively) or ligand affinity (r = 0.413; r = 0.474, respectively). A significant negative correlation was found between total Hg and D2 receptor density (r = -0.340) or ligand affinity (r = -0.346). These correlations suggest that environmentally relevant concentrations of Hg may alter neurochemical function in wild mink, and that neurochemical receptor-binding characteristics can be used as a novel biomarker to assess Hg's effects on wildlife. Given the importance of the muscarinic cholinergic and dopaminergic pathways in animal behavior, further studies are required to explore the physiological and ecological significance of these findings.

What are the toxicological effects of mercury in Arctic biota?

“…For example, changes in the levels of muscarinic cholinergic receptors (increased) and N-methyl-D-aspartate (NMDA) glutamate receptors (decreased) were related to concentrations of brain Hg in wild mink (Basu et al, 2005(Basu et al, , 2007b, common eagles, and bald eagles (Scheuhammer et al, 2008). Several of these neurochemical effects have been substantiated in laboratory studies involving captive mink experimentally fed environmentally realistic MeHg doses (Basu et al, 2006b(Basu et al, , 2007b.…”

Dopamine and social anxiety disorder

“…For example, the psychological features of mercury poisoning (erythrism) such as shyness, fear of ridicule and blushing bear an uncanny resemblance to SAnD and are of interest in light of both modern community concerns of mercury exposure and increasing evidence of mercury-related DA dysfunction. 4 Although work is still at an early stage, animal and human studies suggest that reduced DA function is related to social anxiety. There is also support of a neurodevelopmental basis to SAnD.…”

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

“…Cholinergic signaling pathways have been linked to essential physiological processes including learning, memory, stress response, and modulation of sensory information; the disturbance of dopaminergic neurotransmission is related to psychiatric symptoms in humans (Reis et al 2009). The muscarinic acetylcholine receptor (mAChR) from the cholinergic signaling pathway and monoamine oxidase B (MAO-B) from the dopaminergic signaling pathway are known to be sensitive to MeHg exposure (Chakrabarti et al 1998;Coccini et al 2000;Basu et al 2005aBasu et al , 2006aBasu et al , 2006bBasu et al , 2007aBeyrouty et al 2006;Stamler et al 2006;Coccini et al 2007). The disruption of either of these signaling pathways due to increased THg accumulation in the Arctic could adversely affect beluga whales in the wild.…”