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KMID : 0377220000250020037
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Medical Journal of Chosun Univercity
2000 Volume.25 No. 2 p.37 ~ p.45
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The effects of tumor necrosis factor-a on paraquat toxicity in rats
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Cha Jong-Hee
Park Jung-Su
Yang Seung-Hoon
Park Jae-Yoon
Lee Byoung-Rai
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Abstract
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Background : The toxicity of paraquat is due to the oxygen-derived radicals formed by the reaction of oxygen with bipyridylium radical cations. Tumor necrosis factor (TNF)-α induces the synthesis of mitochondrial manganese superoxide dismutase (Mn-SOD) and other protective proteins in a variety of tumor cells and these protein contribute to a protect tumor cells from free radical injury. In this study, the effects of TNF-α on paraquat-induced toxicity were investigated in rats.
Methods : Experimental animal used was Sprague-Dawley male rat, body weight 150-200g. The paraquat toxicity was determined by survival rate. The SOD, catalse, and glutathione peroxidase(GSHPx) activity were spectrophtomerically determined by Crapo method, Aebi method and Flohe method, respectively.
Results : The survival rate of paraquat-intoxicated rats was decreased by subctaneous injection of TNF-α. However, the survival rate of paraquat injected rats were increased by pretreatment of TNF-α, comparing to saline pretreatment. The liver SOD activity was increased significantly by TNF-α treatment, but kidney and lung enzyme was unaltered in TNF-α treated-rats, comparing to normal control rats. The increment of liver SOD activity by TNF-α treatment was dose- and time-dependant SOD activity of kidney and lung of rats were not changed by TNF-α injection. The activities of catalase and glutathione peroxidase and contents of thiobarbituric acid reactive substance(TBARS) in liver were not changed by TNF-α treatment.
Conclusion : From these result, TNF-α potentiate paraquat toxicity in rats but TNF-α pretreatment reduce paraquat induced toxicity. Protective effect may be resulted from the increased liver SOD activities by TNF-α.
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KEYWORD
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Paraquat, SOD, TNF-α
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