NEUROENDOCRINE EFFECTS OF MERCURY IN SEVERAL FISH SPECIES
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1
University of Michigan, United States
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2
Fish & Wildlife Research Institute, United States
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3
BioDiversity Research Institute, United States
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4
University of Wisconsin-Milwaukee, United States
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5
Michigan State University, United States
Mercury (Hg) is a potent neurotoxicant. Recent studies in fish have also established that Hg is a neuroendocrine disruptor, though little is known about the sub-clinical effects and the underlying mechanisms. Here we present findings from a series of studies (in vitro, field work, laboratory bioassay) that aimed to assess Hg-associated neurochemical effects in several fish species as follows: 1) studies on wild fish (lemon shark, mako shark, seatrout, South River fish); 2) in vitro screening assays (lemon shark, mako shark, yellow perch, goldfish) on neurochemical receptors and enzymes underlying vertebrate reproduction; 3) studies on laboratory-exposed yellow perch. In the wild fish studies, mean brain Hg levels were: 0.145 ppm dry wt in lemon shark (n = 28; South Florida), 1.69 ppm in mako shark (n = 12; Atlantic coast), 0.577 ppm in seatrout (n = 28; South Florida), and 0.069 ppm in South River fish (n = 28; Virginia). Saturation binding curves were developed from each fish species to obtain Bmax (195 – 266 fmol/mg for mAChR, 236 – 3065 fmol/mg for NMDAR) and Kd (3.18 – 4.64 nM for mAChR, 28.9 – 368 nM for NMDAR). Based on inhibition constants (Ki) against Hg2+and CH3Hg+, goldfish and yellow perch were the most sensitive to mAChR and NMDAR binding, respectively. When brain Hg was related to neurochemical enzymes (MAO, AChE) and receptors (mACh, NMDA), there were no Hg-associated neurochemical changes except in the mako shark where a negative correlation with NMDA glutamate receptors (r = 0.496; p < 0.05) was found. Via cell-free in vitro screening assays, we are also assessing Hg-related impacts towards sex hormone receptors, neurotransmitter release and uptake mechanisms, and neurochemical receptors and enzymes that have critical roles in reproduction (e.g, dopamine and GABA systems) and neurobehavior (e.g., glutamate pathway). We will also report on neurochemical data from laboratory-exposed perch.
Keywords:
Ecotoxicology,
Mercury,
Neurotoxicology
Conference:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011.
Presentation Type:
Poster
Topic:
General neuroendocrinology
Citation:
Nam
D,
Head
J,
Adams
DH,
Evers
DC,
Carvan
M,
Goetz
FW,
Murphy
C and
Basu
N
(2011). NEUROENDOCRINE EFFECTS OF MERCURY IN SEVERAL FISH SPECIES.
Front. Endocrinol.
Conference Abstract:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology.
doi: 10.3389/conf.fendo.2011.04.00089
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Received:
21 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Dr. Dong-Ha Nam, University of Michigan, Ann Arbor, United States, dongha@umich.edu
Dr. Nil Basu, University of Michigan, Ann Arbor, United States, niladri@umich.edu