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(W/EH112) Studies on cytotoxicity assays for microcystin detection. Dias, Elsa1, Pereira, Paulo1, Gonçalves, Lídia2, Marques, Sandra2, Garcia, Carlos3, Lagos, Nestor3, Franca, Susana1, 1 2 3 ABSTRACT- Mouse bioassay is the traditional method for total hepatotoxicity assessment in cyanobacteria contaminated field samples. This assay provides a natural physiological and biochemical environment for toxicological assessment. However, besides ethical problems, it is quite insensitive and the faster-acting cyanobacterial neurotoxins may mask the slower-acting hepatotoxins. In recent years, in vitro toxicity tests for microcystins involving cultured cells have been developed to provide a substitute for the mouse bioassay, but there are only a few in vitro studies using permanent cell lines and controversial results have been obtained. Different effects between and within mammalian cell types exposed to microcystins might be related to several variations in the experimental set-up, namely the cell types used, the concentrations and time exposures to toxins, the growth phases at witch toxins were added to cell cultures and the kind of samples tested (purified toxins or crude extracts). In this study, toxic effects of microcystins on five permanent cell lines (HP9, HepG2, Vero, CHO, BHK) were investigated using both purified toxins and field sample extracts. Cell viability was assessed by the colorimetric MTT and lactate dehydrogenase (LDH) assays. The sensitivities of those cell lines to microcystins were compared. Although previous studies suggested that microcystin-LR had no cytotoxic effect on permanent cell lines, preliminary results performed with the above mentioned cells indicated that exposure to microcystins could result in cell membrane damage. Further studies are being done in order to determine the sensitivity of each cell line to microcystins. Key words: microcystin, cyanobacteria, cell lines, cytotoxicity |
