Effects of vitamin E on toxicity by minute amounts of paraquat fed continuously to rats.

The effects of vitamin E on toxicity by minute amounts of paraquat fed continuously for some period to rats were investigated. Two experiments were carried out as experiments 1 and 2. In both experiments, weaning rats were divided at first into two groups; one group was given a vitamin E-deficient diet, and the other a vitamin E-supplemented control diet (50 mg alpha-tocopherol/kg of diet). They were fed on these diets for 40 days. After that, in both experiments, the rats that had been fed the vitamin E-deficient diet were further divided into two groups, which were either given a paraquat-added diet (+PQ-E) or continuously fed the same vitamin E-deficient diet (-E). The amount of paraquat added was 250 mg of methyl viologen per kg of diet. After the addition of paraquat, these two groups were pair-fed. In experiment 1, paraquat was given to all the rats fed the vitamin E-supplemented control diet (+PQ+E). In experiment 2, rats fed the control diet were divided into paraquat-added (+PQ+E) and non-paraquat-added (+E) groups, similar to those of vitamin E-deficient rats. These two groups were also pair-fed thereafter. In both experiments, about 35 days after paraquat addition, they were sacrificed. Plasma and liver alpha-tocopherol contents were measured by HPLC, and liver peroxidation value was measured by chemiluminescence and the TBA method. And, as parameters of vitamin E deficiency, plasma pyruvate kinase and GOT activities and alpha-cysteine proteinase inhibitor (alpha-CPI) level were measured. When the analyzed values were compared between paraquat-added and the corresponding not-added control groups (+PQ-E vs. -E, +PQ+E vs. +E), the following results were obtained. In experiment 1, the values of plasma and liver alpha-tocopherol levels were significantly lower in the +PQ-E group than those of the -E group; however, liver peroxidation values and values of the three parameters of vitamin E deficiency were not different significantly. In experiment 2, the value of liver alpha-tocopherol level was significantly lower in the +PQ+E group than that of the +E group.(ABSTRACT TRUNCATED AT 400 WORDS)