Effects of green tea catechin on enzyme activities and gene expression of antioxidative system in rat liver exposed to microwaves

The purpose of this study was to investigate the effect of green tea catechin on enzyme activities and gene expression of antioxidative system in rat liver exposed to microwaves. Sprague-Dawley male rats 100 +/- 10 g body weight were randomly divided into control group and microwave exposed group: Microwave exposed group was further divided into three groups: catechin free diet (MW) group, 0.25% catechin (MW-0.25C) group and 0.5% catechin (MW-0.5C) group. The rats were irradiated with microwave at frequency of 2.45 GHz for 15 min and then the changes in the pattern of antioxidative defense system and gene expression were investigated for 16 days (the 2nd, 4th, 6th, 8th and 16th days), and compared with the control group. The activity of superoxide dismutase (SOD) in MW group was lower on the 4th day after irradiation and increased in the catechin supplementation group were on the 8th day, compared with control group. The activity of glutathone peroxidase (GSHpx) in MW group was lower than that in the control group on the 8th day after irradiation, but increased to the level of the control group on the 16th day and those of MW-0.25C and MW-0.5C groups showed the same level as the control group but that was higher than the control group from 6 days after irradiation. The content of thiobarbituric acid reactive substances (TBARS) in liver of MW group was increased to 1.3, 1.5, and 1.7 fold of the control group at 2, 4, and 6 days after irradiation respectively but that in MW-0.25C and MW-0.5C groups was increased to 1.1, 1.3 and 1,3 fold of the control group at 2, 4, and 6 days but recovered to the level of the control group at 16 days after irradiation. The level of SOD gene expression in MW group was lower than that in the control group but that of MW-0.25C and MW-0.5C group were higher than the MW group. The GSHpx gene expression in MW group was expressed lower than in the control group, but expressed at a higher level in the MW-0.25C and MW-0.5C groups. It is suggested that the damage of liver tissues was alleviated and function rapidly recovered to the normal level due to probable to the correction of imbalances in the antioxidative system with the administration of green tea catechin (C) 2002 Elsevier Science Inc. All rights reserved.