title: Oxidative mechanisms of fish hepatocyte toxicity by the harmful dinoflagellate Cochlodinium polykrikoides.
abstract: 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.
authors.affiliation: Faculty of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, P.O. Box 14155-6153, Iran.
authors.forename: Jafar
authors.initials: J
authors.lastname: Shahraki
authors.forename: Abbasali
authors.initials: A
authors.lastname: Motallebi
authors.forename: Jalal
authors.initials: J
authors.lastname: Pourahmad
mesh_terms: D000818:Animals; D004141:Dinoflagellida / Q000502:physiology*; D005393:Fish Diseases / Q000378:metabolism* / Q000469:parasitology; D057097:Harmful Algal Bloom; D022781:Hepatocytes / Q000378:metabolism / Q000469:parasitology*; D008163:Luminescent Measurements / Q000662:veterinary; D053078:Membrane Potential, Mitochondrial; D008930:Mitochondria, Liver / Q000378:metabolism / Q000469:parasitology*; D017686:Oncorhynchus mykiss / Q000378:metabolism / Q000469:parasitology*; D010084:Oxidation-Reduction; D011529:Protozoan Infections, Animal / Q000378:metabolism* / Q000469:parasitology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000662:veterinary
chemical_list: D017382:Reactive Oxygen Species