克山病病区粮食中补充蛋氨酸对大鼠膳食硒生物利用的影响

为研究在克山病病区粮食中补充蛋氨酸对大鼠组织硒和谷胱甘肽过氧化物酶 (GPX)活性的影响 ,用克山病病区生产的低硒粮食为主配成低硒基础饲料 ,其硒含量为 0 .0 0 7mg/kg。在此基础上添加不同量的硒蛋氨酸 ,使饲料硒水平分别达到 0 .0 0 7、0 .0 6和 0 .5 0 mg/kg。每一硒水平又分别补充或不补充 4g/kg DL -蛋氨酸 ,配制成含不同硒和蛋氨酸的 6种饲料 ,分别喂养雄性 Wistar断乳大鼠 8周。结果在饲料硒水平为0 .0 0 7mg/kg时 ,补充蛋氨酸组动物除肌肉硒含量低于未补充组外 ,其它组织硒含量和各组织 GPX活力与不补充蛋氨酸动物无显著差异 ;在饲料硒水平为 0 .0 6 mg/kg时 ,补充蛋氨酸组动物组织中的硒含量出现了重新分布 ,最明显的是补充蛋氨酸组动物肌肉的硒含量减少 ,而肝脏和血硒含量增加 ,且各组织中 GPX活力显著大于未补充蛋氨酸组的动物 ;在饲料硒水平为 0 .5 0 mg/kg时 ,补充蛋氨酸组动物组织中硒含量有不同程度下降 ,但 GPX活力仍保持不变。研究结果认为病区粮食中蛋氨酸不足时 ,机体首先利用膳食中的硒蛋氨酸(谷类食物中硒的主要形式 )以替代蛋氨酸参与组织蛋白质的合成。补充蛋氨酸后 ,硒蛋氨酸即可发挥其应有生理功能。进一步提示病区粮食中蛋氨酸不足可能是与克山病发病有关的另一因素。

Effect of methionine supplementation on the selenium bioavailability in rats fed on grains from Keshan Disease endemic area

In order to study the effect of dietary methionine on tissue selenium and glutathione peroxidase activity(GPX) in rats fed on grains from Keshan Disease endemic area, a nonpurified selenium(Se) deficient diet(containing Se 0 007mg/kg diet)taken from Keshan Disease endemic area was supplemented with selenomethionine (SeMet) to provide selenium content in diet for 0 007,0 06 and 0 50mg/kg and added or not added with DL methionine (Met) 4g/kg to make 6 kinds of diet. Fifty four male weanling Wistar rats were randomly divided into 6 groups, consuming each one of the 6 diets for 8 weeks. The Se content and GPX activity in tissues of animals with Met supplementation were compared with those without Met supplementation. The results showed that adding Met did not result in significant changes of tissue Se content and GPX activity in animals having dietary Se of 0 007mg/kg, except for lower muscle Se content. However, in animals having dietary Se of 0 06mg/kg and supplementing Met resulted in selenium redistribution in tissues decrease of Se content in muscle, increase of Se content in liver and blood and significant elevation of GPX activity in all tissues. In animals having methionine added and dietary Se of 0 50mg/kg, tissue Se content declined to various extent, while GPX activity remained unchanged. The results suggest that SeMet(main chemical form of Se in cereals) is preferentially incorporated into body protein when dietary methionine is limited. Once Met is supplemented, dietary SeMet would provide more Se for the syntheses of GPX and other selenoproteins. The results further suggest that marginal deficiency in sulfur contaning amino acids in the diet from Keshan Disease endemic area might be an additional factor for the development of Keshan Disease under selenium deficiency.