title: Morphological evidence of neurotoxicity in retina after methylmercury exposure.
abstract: The visual system is particularly sensitive to methylmercury (MeHg) exposure and, therefore, provides a useful model for investigating the fundamental mechanisms that direct toxic effects. During a period of 70 days, adult of a freshwater fish species Hoplias malabaricus were fed with fish prey previously labeled with two different doses of methylmercury (0.075 and 0.75 μgg(-1)) to determine the mercury distribution and morphological changes in the retina. Mercury deposits were found in the photoreceptor layer, in the inner plexiform layer and in the outer plexiform layer, demonstrating a dose-dependent bioaccumulation. The ultrastructure analysis of retina revealed a cellular deterioration in the photoreceptor layer, morphological changes in the inner and outer segments of rods, structural changes in the plasma membrane of rods and double cones, changes in the process of removal of membranous discs and a structural discontinuity. These results lead to the conclusion that methylmercury is able to cross the blood-retina barrier, accumulate in the cells and layers of retina and induce changes in photoreceptors of H. malabaricus even under subchronic exposure.
authors.affiliation: Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Maritana
authors.initials: M
authors.lastname: Mela
authors.forename: Sonia Regina
authors.initials: SR
authors.lastname: Grötzner
authors.forename: Alexia
authors.initials: A
authors.lastname: Legeay
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mesmer-Dudons
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Massabuau
authors.forename: Dora Fix
authors.initials: DF
authors.lastname: Ventura
authors.forename: Ciro Alberto
authors.initials: CA
authors.lastname: de Oliveira Ribeiro
mesh_terms: D000818:Animals; D001813:Blood-Retinal Barrier / Q000187:drug effects / Q000378:metabolism; D001822:Body Burden; D060125:Characiformes; D004305:Dose-Response Relationship, Drug; D020387:Food Chain; D005506:Food Contamination; D005618:Fresh Water; D020262:Mercury Poisoning, Nervous System / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D008767:Methylmercury Compounds / Q000378:metabolism / Q000633:toxicity*; D010539:Permeability; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D012160:Retina / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical