Vitamin B-6 status on cysteine, glutathione and related enzyme activities in mice with homocysteine-induced oxidative stress

• Main Authors: Wan-Ju Lee, 李宛儒
• Other Authors: Yi-Chia Huang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/27482623668073936356

碩士 === 中山醫學大學 === 營養學研究所 === 102 === Vitamin B-6 (pyridoxal 5’-phosphate, PLP) serves as a coenzyme in the synthesis of cysteine. Cysteine is an important contributor to synthesis of reduced glutathione (GSH). Vitamin B-6 thus may indirectly play a role in the GSH antioxidant defense system, although the exact role has not been fully confirmed yet. The purpose of this study was to examine the effects of vitamin B-6 status on cysteine, GSH and its related enzyme activities in mice with homocysteine-induced oxidative stress. After 7 days of acclimatization, fifty mice were divided into five groups fed either a normal diet (2 groups, 7 mg/kg of pyridoxine-HCl), a vitamin B-6 deficient diet (pyridoxine-HCl free), B-6 supplemented diet I (14 mg/kg of pyridoxine-HCl) and B-6 supplemented diet II (35 mg/kg of pyridoxine-HCl) for 28 days. Homocysteine thiolactone was then added to drinking water in 4 groups except for one control group for 21 days to induce oxidative stress. At the end of this study, mice were decapitated and blood, liver and kidney tissue samples were obtained. PLP, homocysteine, cysteine, GSH, malondialdehyde (MDA), glutathione peroxidase (GPx) and glutathione reductase (GR) activities in plasma and tissues were measured. The result showed that mice with vitamin B-6 deficient diet had the lowest PLP concentration, the highest MDA and homocysteine concentrations when compared with those of mice with control or vitamin B-6 supplemented diet. Among homocysteine-treated groups, GSH concentration, GPx and GR activities remained relatively stable in plasma and tissues no matter vitamin B-6 was depleted or repleted. Plasma PLP negatively correlated with homocysteine and MDA, positively correlated with hepatic GSH concentration. Although deficient vintamin B-6 may have an antioxidative effect under homocysteine-induced oxidative stress, the changes of vitamin B-6 status did not mediate the oxidative stress in connection with cysteine and GSH synthesis and its related enzyme activities in mice.