Abstract: Objective: To study the effect of different doses of manganese (Mn) on oxidative damage of liver mitochondrial induced by Mn chloride,and to explore the cell molecular mechanism of Mn-induced exeitotoxicity.Methods: Twenty four male SD rats were randomly divided into four groups by weight.The first group (control group) were given subcutaneous injection of physiological saline only;the second group (Mn-exposed group) were injected 32 mg/kg of MnCl₂ subcutaneously;the third and fourth groups were intraperitoneally injected 100 mg/kg of taurine (Tau) and 1 mg/kg of cyclosporine A (CSA),respectively.Two hours after subcutaneous injection,the first group were intraperitoneally injected physiological saline,and the other three groups received intraperitoneal injection of 32 mg/kg of MnCl₂ for 30 days,and Tau and CSA were injected every other day for 15 times.At the 24th hour after the last administration of MnCl₂,the rats were killed and the liver was taken to detect the mitochondrial swelling amplitude,mitochondrial membrane potential (MMP),permeability transition pore (PT pore),the activity of GSH-PX,SDH and the content of cytochrome C and OH·.Results: Compared with control group,the mitochondrial swelling amplitude,PT pore,MMP,the activity of GSH-PX and SDH decreased in the MnCl₂ group,while the content of cytochrome C and OH·increased (P<0.05 to P<0.01).Compared with MnCl₂ group,the mitochondrial swelling amplitude,PT pore and MMP increased in Tau pretreatment group (P<0.05 to P<0.01),while the activity of GSH-PX and SDH increased,and the content of cytochrome C and OH·decreased (P<0.01).Compared with control group,the activity of GSH-PX and SDH,PT pore and MMP increased in CSA pretreatment group,while the content of cytochrome C decreased (P<0.01).Conclusions: Tau and CSA have some antagonistic effects on oxidative damage of liver mitochondrial induced by manganese.