Liver slice culture for assessing hepatotoxicity of freshwater cyanobacteria

1 A modified mouse liver slice culture technique was established and the viability of the system was assessed on the basis of leakage of cytosolic enzymes viz. lactate dehydrogenase (LDH), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartic aminotransferase (AST) and slice histology. 2 This system was employed for toxicity screening of five algal species of Indian origin on the basis of the EC(50) for LDH leakage (dose of cyanobacteria resulting in leakage of 50% of enzyme) of a known toxic cyanobacterial strain Microcystis aeruginosa (PCC 7820). On the basis of both in vitro and in vivo toxicity none of the five species screened exhibited toxicity. 3 The toxicity of PCC 7820 was compared with a purified cyanobacterial hepatotoxin, Microcystin-LR. Various biochemical indices and histological changes confirm the hepatotoxic nature of the toxins. 4 The toxins did not induce glutathione-mediated lipid peroxidation but they did cause significant mitochondrial damage based on an MTT assay. 5 The study illustrates the utility of this in vitro system in identifying naturally occurring toxic cyanobacteria, particularly hepatotoxic species.