Faculty Collaboration Database

Selenomethionine reduces visual deficits due to developmental methylmercury exposures. Physiol Behav 2008 Jan 28;93(1-2):250-60

Date

10/02/2007

Pubmed ID

17905328

Pubmed Central ID

PMC2265788

DOI

10.1016/j.physbeh.2007.08.023

Scopus ID

2-s2.0-42449160706 (requires institutional sign-in at Scopus site)   55 Citations

Abstract

Developmental exposures to methylmercury (MeHg) have life-long behavioral effects. Many micronutrients, including selenium, are involved in cellular defenses against oxidative stress and may reduce the severity of MeHg-induced deficits. Zebrafish embryos (<4 h post fertilization, hpf) were exposed to combinations of 0.0-0.30 microM MeHg and/or selenomethionine (SeMet) until 24 hpf then placed in clean medium. Fish were tested as adults under low light conditions ( approximately 60 microW/m(2)) for visual responses to a rotating black bar. Dose-dependent responses to MeHg exposure were evident (ANOVA, P<0.001) as evidenced by reduced responsiveness, whereas SeMet did not induce deficits except at 0.3 microM. Ratios of SeMet:MeHg of 1:1 or 1:3 resulted in responses that were indistinguishable from controls (ANOVA, P<0.001). No gross histopathologies were observed (H&E stain) in the retina or optic tectum at any MeHg concentration. Whole-cell, voltage-gated, depolarization-elicited outward K(+) currents of bipolar cells in intact retina of slices adult zebrafish were recorded and outward K(+) current amplitude was larger in bipolar cells of MeHg-treated fish. This was due to the intense response of cells expressing the delayed rectifying I(K) current; cells expressing the transient I(A) current displayed a slight trend for smaller amplitude among MeHg-treated fish. Developmental co-exposure to SeMet reduced but did not eliminate the increase in the MeHg-induced I(K) response, however, I(A) responses increased significantly over MeHg-treated fish to match control levels. Electrophysiological deficits parallel behavioral patterns in MeHg-treated fish, i.e., initial reactions to the rotating bar were followed by periods of inactivity and then a resumption of responses.

Author List

Weber DN, Connaughton VP, Dellinger JA, Klemer D, Udvadia A, Carvan MJ 3rd

Author

Ava Udvadia BS,PhD Associate Professor in the Biological Sciences department at University of Wisconsin - Milwaukee

MESH terms used to index this publication - Major topics in bold

Analysis of Variance
Animals
Behavior, Animal
Cell Differentiation
Dose-Response Relationship, Drug
Drug Interactions
Electroretinography
Embryo, Nonmammalian
Embryonic Development
Female
Male
Mercury Poisoning, Nervous System
Methylmercury Compounds
Neuroprotective Agents
Potassium Channels
Prenatal Exposure Delayed Effects
Retina
Retinal Bipolar Cells
Selenomethionine
Superior Colliculi
Visual Pathways
Zebrafish