Oxidative mechanisms of fish hepatocyte toxicity by the harmful dinoflagellate Cochlodinium polykrikoides

• Published in: Marine environmental research Vol. 87-88; pp. 52 - 60
• Main Authors: Shahraki, Jafar, Motallebi, Abbasali, Pourahmad, Jalal
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.2013; Elsevier
• Subjects: adenosine diphosphate; adenosine triphosphate; Agnatha. Pisces; algal blooms; Animal and plant ecology; Animal, plant and microbial ecology; Animals; apoptosis; Applied ecology; Biological and medical sciences; caspase-3; cytochrome c; cytosol; cytotoxicity; Dinoflagellida - physiology; Dinophyceae; Ecotoxicology, biological effects of pollution; farmed fish; Fish; Fish Diseases - metabolism; Fish Diseases - parasitology; free radical scavengers; Fundamental and applied biological sciences. Psychology; glutathione; Harmful Algal Bloom; hepatocytes; Hepatocytes - metabolism; Hepatocytes - parasitology; liver; Luminescent Measurements - veterinary; Lysosomes; membrane potential; Membrane Potential, Mitochondrial; Metabolites; Microsomal oxidases; Mitochondria, Liver - metabolism; Mitochondria, Liver - parasitology; mitochondrial membrane; Oncorhynchus mykiss; Oncorhynchus mykiss - metabolism; Oncorhynchus mykiss - parasitology; Oxidation-Reduction; permeability; Protozoan Infections, Animal - metabolism; Protozoan Infections, Animal - parasitology; reactive oxygen species; Reactive Oxygen Species - metabolism; Sea water ecosystems; Spectrometry, Fluorescence - veterinary; Synecology; Toxicity; trout; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Lysosomes; Fish; Microsomal oxidases; Metabolites; Toxicity; Protozoa; Digestive system; Enzyme; Metabolite; Algae; Liver; Lysosome; Oxidase; Marine environment; Vertebrata; Hepatocyte; Pisces; Oxidoreductases; Harmful alga
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/j.marenvres.2013.03.004

Harmful Algal Blooms caused by the marine ichthyotoxic dinoflagellate Cochlodinium polykrikoides are responsible for mass mortalities of wild and farmed fish worldwide. In this research, we investigated the cytotoxic mechanisms of aqueous extract of C. polykrikoides on isolated Rainbow trout (Oncorhynchus mykiss) liver hepatocytes. Algal extract exposure with isolated trout hepatocytes caused hepatocyte membrane lysis, reactive oxygen species (ROS) formation, glutathione depletion, lysosomal membrane rupture, collapse of mitochondrial membrane potential, ATP depletion and increase in ADP/ATP ratio, cytochrome C release into the hepatocyte cytosol, and activation of caspases cascade. Anti-oxidants, free radical scavengers, mitochondrial permeability transition (MPT) pore sealing agents, microsomal oxidases inhibitors, ATP generators and lysosomotropic agents protected fish hepatocytes against C. polykrikoides. Fish hepatocyte toxicity was also associated with mitochondrial and lysosomal membrane injury. These events caused cytochrome C release from the mitochondrial intra-membrane space into cytosol. The cytochrome C release could trigger activation of caspase-3 and apoptosis. •Cochlodinium polykrikoides extract induced cytotoxicity in trout hepatocytes.•C. polykrikoides extract increased ROS formation in trout hepatocytes.•Cytochrome P450, mitochondria and lysosomes are involved in ROS formation.•Lysosomal-mitochondrial cross-talk potentiates C. polykrikoides ichthyotoxicity.•Cytochrome c release and caspase-3 activation orchestrated cell death signaling.