title: Dualistic evolution of liver damage in mice triggered by a single sublethal exposure to Microcystin-LR.
abstract: Microcystins (MCYST) are the most frequently reported cyanotoxins in human poisoning incidents. Despite the well-described mechanism of acute and lethal injury, the sublethal effects of this toxin require further investigation. The aim of this study was to contribute to the knowledge of the variant MCYST-LR effects at sublethal doses by investigating biochemical changes and tissue damage in a murine model. For this purpose, mice were intraperitoneally injected with 45 μg of MCYST-LR/kg body weight. Their organs were collected at 2, 8, 24, 48 or 96 h after injection. Control animals received saline solution. We detected oxidative imbalance in the liver, particularly at 8 h after exposure. Furthermore, biomarkers of liver injury were detected in high concentration in the serum of the exposed animals. Stereological analyses of the liver indicated two different phases in the intoxication process: an initial phase characterized by an increase in steatosis was followed by a second, later phase characterized by increased inflammation and hepatocyte binucleation. Formation of areas of necrosis and increased blood vessel diameter were observed throughout the experimental period. The number of hepatocytes per area unit also decreased. However, these parameters recovered over the period of exposure. MCYST accumulated in liver and was detectable until the end of the monitoring period. These results confirm the necessity for further studies of processes involved in sublethal exposure to MCYST.
authors.affiliation: Laboratory of Ecophysiology and Toxicology of Cyanobacteria, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: L J
authors.initials: LJ
authors.lastname: Mattos
authors.affiliation: Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: S S
authors.initials: SS
authors.lastname: Valença
authors.affiliation: Laboratory of Ecophysiology and Toxicology of Cyanobacteria, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: S M F O
authors.initials: SM
authors.lastname: Azevedo
authors.affiliation: Laboratory of Ecophysiology and Toxicology of Cyanobacteria, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Federal University of Rio de Janeiro, Campus Xerem, Duque de Caxias, Rio de Janeiro, Brazil. Electronic address: rmsoares@xerem.ufrj.br.
authors.forename: R M
authors.initials: RM
authors.lastname: Soares
mesh_terms: D000818:Animals; D022781:Hepatocytes / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D008297:Male; D008387:Marine Toxins; D051379:Mice; D052998:Microcystins / Q000633:toxicity*; D009336:Necrosis / Q000139:chemically induced; D010084:Oxidation-Reduction; D018675:Toxicity Tests
chemical_list: D008387:Marine Toxins; D052998:Microcystins; C057862:cyanoginosin LR
keywords: Inflammation; Liver; Microcystin; Stereology; Sublethal dose