維生素 B-6對同半胱胺酸誘發小鼠氧化壓力後之半胱胺酸、穀胱甘肽及相關抗氧化酵素之影響

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

李宛儒(Wan-Ju Lee)

指導教授 ： 黃怡嘉

中山醫學大學/健康管理學院/營養學研究所/碩士(2014年)

https://doi.org/10.6834/CSMU.2014.00151

摘要

維生素 B-6擔任半胱胺酸形成過程中的輔酶，半胱胺酸會進而形成穀胱甘肽，因此維生素 B-6被認為可能具有間接抗氧化功能，但其角色尚未被確定。本研究以動物模式探討維生素B-6對同半胱胺酸誘發氧化壓力後的半胱胺酸、穀胱甘肽及相關抗氧化酵素活性之影響。50隻BALB/c雄性小鼠經過7天的適應期後隨機分為五組，分別為對照組 (7 mg/diet 維生素 B-6)、控制組 (7 mg/diet 維生素 B-6)、維生素 B-6缺乏組 (0 mg/diet 維生素 B-6)、維生素 B-6補充組I (14 mg/diet維生素B-6) 及維生素B-6補充組II ( 35 mg/diet 維生素 B-6)，餵食28天後除控制組外皆在水中添加同半胱胺酸。經過 21天後犧牲小鼠，分析其血漿、肝臟及腎臟的血漿磷酸比哆醛 (pyridoxal 5’-phosphate, PLP)、同半胱胺酸、半胱胺酸、丙二醛 (malondialdehyde, MDA)、穀胱甘肽濃度及其相關酵素活性。結果發現，維生素 B-6缺乏組小鼠之血漿PLP濃度顯著較低，且同半胱胺酸及 MDA濃度顯著較高，而維生素 B-6正常或補充組皆無顯著差異。肝及腎臟的半胱胺酸及穀胱甘肽濃度以及血漿和肝腎組織的穀胱甘肽過氧化酶及穀胱甘肽還原酶活性在各組間皆沒有顯著差異。血漿的PLP濃度與同半胱胺酸及肝臟 MDA皆呈顯著負相關，但與肝臟穀胱甘肽呈正相關。雖然小鼠在維生素 B-6攝取缺乏情況下會顯著增加同半胱胺酸所誘發的氧化壓力，但不同維生素 B-6的攝取量似乎不會影響半胱胺酸及穀胱甘肽濃度以及其相關抗氧化酵素活性，維生素 B-6在間接抗氧化功能所扮演的角色仍需進ㄧ步研究。

關鍵字

維生素 B-6 ； 氧化壓力 ； 半胱胺酸 ； 穀胱甘肽抗氧化酵素活性

並列摘要

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.

並列關鍵字

Vitamin B-6 ； oxidative stress ； cysteine ； glutathione ； antioxidant enzyme activity

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