锌对心理应激大鼠不同脑区金属硫蛋白亚型表达的影响

目的:观察不同锌摄入水平对心理应激大鼠不同脑区金属硫蛋白亚型表达的影响。方法:将Wistar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、缺锌和补锌饲料,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1w后开始束缚应激,持续4w。分别以蛋白印迹法和RT-PCR测定海马、皮质、间脑和嗅球金属硫蛋白含量以及MT-1mRNA和MT-3mRNA的表达;并以ELISA法检测血浆IL-6和IL-1的含量。结果:缺锌动物的血锌含量明显降低,缺锌应激动物不同脑区金属硫蛋白及其亚型mRNA的表达均较缺锌动物明显升高,但其增加幅度低于其它应激组;而补锌应激动物的表达增加幅度最大。缺锌组和各应激组动物的血浆皮质醇、IL-1、IL-6水平出现显著升高。另外,金属硫蛋白在不同脑区的表达水平不同:海马>嗅球>皮质>间脑。结论:不同锌营养状况可影响心理应激动物不同脑区金属硫蛋白的表达,海马脑区表达水平较高可能与海马在应激反应中的重要作用相关联。糖皮质激素及IL-6、IL-1等细胞因子可能对金属硫蛋白的表达发挥了诱导作用。

EFFECTS OF ZINC ON THE EXPRESSION OF METALLOTHIONEIN ISOFORMS IN DIFFERENT BRAIN DOMAINS IN RATS UNDER STRESS

Objective: To explore the effects of different doses of Zn on the expression of metallo- thionein(MT) isoforms in hippocampus, olfactory bulb, diencephalon and cortex in stress rats. Method: The animal model of psychological stress was developed by restraint for 4w. Wistar rats were randomly assigned to 8 groups: control group, Zn-deficient group, pair-fed group, Zn -supplemented group and their corresponding stress groups. The expressions of MTs and their mRNAs were detected by Western blot and RT-PCR respectively. Results: In Zn-deficient group, plasma zinc content was decreased, while in Zn -supplemented group slightly increased. Compared with Zn-deficient group, the stress Zn -deficient group had higher expressions of MTs and MT-1 mRNA, MT-3 mRNA in hippocampus, olfactory bulb, diencephalon and cortex. Expressions of MTs in Zn-supplemented group were increased, and much more in corresponding stress group. In addition, the levels of plasma cortisol, IL-6 and IL-1 were increased clearly in Zn-deficient group and stress groups. Moreover, MTs’ productions were different in four brain domains,the highest in hippocampus and the lowest in diencephalon. Conclusion: Zn may affect the expressions of MTs and MT-1 mRNA, MT-3 mRNA in different regions of brain in stress rats. The higher production of MTs in hippocampus may be related to its role in body’s adaptation to stress. Cortisol, IL-6 and IL-1 may be involved in the modulation of expression of MTs.