title: Bioaccumulation, oxidative stress and HSP70 expression in Cyprinus carpio L. exposed to microcystin-LR under laboratory conditions.
abstract: Microcystin-LR (MC-LR) produced by cyanobacteria are potent specific hepatotoxins. So far the pathogenesis of environmental MC-LR toxicity to aquatic organisms has not been fully elucidated. In the present study the accumulation of MC-LR was investigated in various organs/tissues of Cyprinus carpio L. (C. carpio) following exposure to MC-LR for 14 d at environmentally relevant concentrations (0.1 to 10 μg L(-1)). Results showed that the presence of MC-LR enhanced toxin accumulation in all investigated organs and the highest accumulation was found in the liver of fish exposed to 5.0 μg L(-1) of MC-LR. An EPR analysis indicated ·OH intensity in liver was significantly induced at 0.1 μg L(-1) of MC-LR and then restored when the MC-LR concentration was greater than 0.1 μg L(-1). After 14-day exposure, MC-LR (1.0-10.0 μg L(-1) of MC-LR) caused a pronounced promotion of glutathione S-transferase (GST) activity and a depletion of reduced glutathione (GSH) content in fish liver, which indicated that GSH was involved in detoxification of MC-LR and the conjugation reaction of MC-LR and GSH occurred. A mild oxidative damage was evidenced by the accumulation of malondialdehyde (MDA) level at 5.0 μg L(-1) of MC-LR exposure, but which was restored when the MC-LR concentration was increased to 10.0 μg L(-1). The responses of antioxidant enzymes and the induction of HSP70 expression might contribute to MC-LR tolerance of C. carpio. However, the protein phosphatase (PP) activities were strikingly inhibited in all treated groups. Thus, the overall toxicity of environmental MC-LR on C. carpio seems to be initiated in the liver via both the ROS pathway and the PP inhibition pathway, and the latter might be more important when ambient MC-LR concentration is greater than 0.1 μg L(-1). More importantly, these results can help to support the evaluation on the potential effects of MC-LR under common environmental concentrations.
authors.affiliation: Nanjing Institute of Environmental Sciences, Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Ministry of Environmental Protection, Nanjing 210042, PR China.
authors.forename: Jinlin
authors.initials: J
authors.lastname: Jiang
authors.forename: Yue
authors.initials: Y
authors.lastname: Shi
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Shan
authors.forename: Liuyan
authors.initials: L
authors.lastname: Yang
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wang
authors.forename: Lili
authors.initials: L
authors.lastname: Shi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002347:Carps / Q000378:metabolism*; D004789:Enzyme Activation; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D015227:Lipid Peroxidation; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D008387:Marine Toxins; D052998:Microcystins / Q000009:adverse effects* / Q000493:pharmacokinetics; D018384:Oxidative Stress; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D017382:Reactive Oxygen Species; D013997:Time Factors
chemical_list: D000975:Antioxidants; D018840:HSP70 Heat-Shock Proteins; D008387:Marine Toxins; D052998:Microcystins; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D005982:Glutathione Transferase; D010749:Phosphoprotein Phosphatases; C057862:cyanoginosin LR; D005978:Glutathione