Abstract: OBJECTIVE: To study the toxic oxidative damage in PC12 cells caused by microcystins-LR ( MC-LR). METHODS： MTT assays and lactate dehydrogenase (LDH) in culture medium of PC12 cells were performed to assess the toxicity of MC-LR. The contents of MDA，SOD，GSH-Px and CAT were measured with kits. RESULTS：MTT assay showed that MC-LR had an inhibitory effect on PC12 cells，and the IC50 of MC-LR were 89.06，47.24，33.13 μg/L at 12 h，24 h and 48 h，respectively. Twenty-four hours after treatment by MC-LR，the production of LDH in culture medium was increased. Compared with control group，the contents of MDA and SOD were apparent when MC-LR was more than 10 μg/L (P＜0.05). The catalase activity change was similar to SOD. GSH-Px content showed no significant difference compared with the control group. CONCLUSION： MC-LR could inhibit proliferation and induce membrane damage and oxidative damage in PC12 cells．

Key words: microcystin-LR, neurotoxicity, PC12 cells, lactate dehydrogenase, oxidative damage