New insight in colistin induced neurotoxicity with the mitochondrial dysfunction in mice central nervous tissues

In the present study, the mechanism of colistin-induced neurotoxicity was investigated with a focus on behavioral characters, mitochondrial ultrastructures and functions of the central nerve tissues in mice followed by administrating intravenously 15 (divided into two dose and 12 h apart), 7.5 and 5 mg/kg bw colistin sulfate for 1, 3 or 7 days successively. To assess the recoverability of colistin-induced neurotoxicity, the neurotoxicity was also examined on day 15 (8 post colistin sulfate administration for 7 days). The results showed that, the spontaneous activities of mice were significantly decreased on days 3 and 7 in the 15 mg/kg group compared with the correspondingly control group. The abnormal ultrastructure changes of mitochondria were presented in their nervous tissues and changed in a dose- and time-dependent manner, e.g. severe vacuolation and fission on days 3 and 7 in the 15 mg/kg group and more slight on day 7 in the 7.5 mg/kg group. In addition, mitochondrial permeability transition (MPT), membrane potential (Δψm) and activities of mitochondrial succinate dehydrogenase changed, showing that colistin affected the mitochondrial functions. The recoverability of colistin-induced neurotoxicity was showed and only slight injury occurred in the nerve tissues of mice on day 15 in the 15 mg/kg group and it had no abnormal changes in the behavioral and neuropathology characters in mice on day 15 in the 7.5 and 5 mg/kg groups. The results suggested that mitochondrial dysfunction might partly account for the mechanism of neurotoxicity induced by colistin sulfate.