锌对应激大鼠海马金属硫蛋白亚型表达的调控作用及机制研究

Effects of zinc on the expression of metallothionein isoforms in hippocampus of stressed rats

目的 观察不同锌摄入水平对应激大鼠海马脑区不同金属硫蛋白亚型表达的影响。方法 将Wistar雄性大鼠随机分为 8组 :正常对照组、对喂组、缺锌组和补锌组及其相应的应激组 ,分别给予正常饲料、缺锌饲料和补锌饲料 ,以缺锌动物当日的饲料摄入量作为对喂动物次日的给料量。动物喂饲 1周后开始束缚应激 ,持续 4周。以血红蛋白镉饱和法测定脑组织金属硫蛋白含量 ,分离海马提取总RNA ,以RT PCR检测金属硫蛋白亚型MT -1mRNA和MT -3mRNA。结果 缺锌动物出现血锌含量明显降低 ,脑组织金属硫蛋白含量和海马金属硫蛋白mRNA的表达均出现降低 ,但其表达在缺锌应激组动物仍有明显升高 ;而补锌动物金属硫蛋白的表达有所增加 ,补锌应激组动物的表达增加更加明显。缺锌和缺锌应激组动物的血浆皮质醇、IL -1、IL- 6和NO水平也较其它组显著升高。结论 缺锌可降低动物脑和海马组织中金属硫蛋白的表达 ,但缺锌动物在接受应激刺激后 ,金属硫蛋白的表达仍可明显增加 ;而补锌可增加金属硫蛋白的表达 ,补锌应激使脑组织中金属硫蛋白的表达升高更为显著 ;应激对动物的损伤作用与其锌营养状况有关 ,缺锌可降低机体对应激的抵抗能力。

Objective\ This study was conducted to evaluate the effects of differe nt doses of zinc on the expression of metallothionein isoforms in hippocampus of stressed rats. Methods The animal model of psychological str ess was developed by restraint stress for four weeks. Wistar rats were randomly assigned to eight groups as follows: control group, zinc deficiency group, pair-feed group, zinc c omplementarity group and their corresponding stressed groups. Results In zinc deficiency group, plasm zinc content was decreased, while in zinc complementarity group it's slightly increased. On the one hand, the expressions of metallothionein in brain and MT-1 mRNA , MT-3 mRNA in hippocampus were dow nregulated in zinc deficiency group, however, their expressions were evidently enhanced in stresse d zinc deficiency group. On the other hand, inductions of metallothionein and it 's mRNAs in zinc complementarity group were increased, furthermore, stressed zin c complementarity group has more significantly yield of metallothionein and it's mRNAs. In addition, the levels of plasma cortisol, IL-6, IL-1 and NO were inc re ased clearly in zinc deficiency group and stressed zinc deficiency group. Conclusion Our results suggested that zinc deficiency may decrease while zinc complem entarety increase the expressions of metallothionein in brain and MT-1 mRNA, MT - 3 mRNA in hippocampus, moreover, stress can increased their expressions dramatic ally. The impairment of stress on body may be involved with the nutrition status of zinc, and zinc deficiency can lower the body's resistibility to stress.