血管性痴呆大鼠突触后致密物质变化机制的研究

目的观察血管性痴呆(VaD)大鼠N-甲基D-天冬氨酸受体(NMDAR)的2B亚基(NR2B)和钙/钙调蛋白依赖性蛋白激酶Ⅱ(CaMKⅡ)的变化情况,探讨其在VaD发生、发展中的作用。方法将96只Wistar大鼠随机分为假手术组(32只)、VaD模型组(模型组,32只)和美金刚治疗组(治疗组,32只)。采用永久性结扎双侧颈总动脉方法制备VaD大鼠模型。用RT-PCR法检测术后4、8、12、16用犬鼠海马NR2B mRNA的表迭,用γ-~(32)P掺入法检测大鼠海马CaMKⅡ的活性。结果与假手术组比较,模型组海马NR2B mRNA水平术后4周时明显增高(P<0.05),术后8～16周显著降低(P<0.01),海马总CaMKⅡ活性术后4周时明显增高(P<0.01),术后12周、16周明显降低(P<0.01);治疗组术后4周时上述2项结果与假手术组差异无统计学意义,除治疗组8周时,在其他时间点,与假手术组差异有统计学意义(P<0.05,P<0.01);但NR2BmRNA水平于术后8周、12周明显高于模型组(P<0.01,P<0.05);总CaMKⅡ活性与模型组差异无统计学意义。结论 CaMKⅡ活性变化主要是NMDAR介导的,美金刚通过调节NR2B表达改善VaD大鼠认知功能,但对CaMKⅡ活性的影响有限。

The mechanism of changes of postsynaptic dense substances in vascular dementia rats

Objective To investigate the relationship of altered expression of N-methyl-D-aspartic acid receptor 2B(NR2B) and ealcium/calmodulin-dependent protein kinase Ⅱ (CaMK Ⅱ) to development of vascular dementia in rats. Methods Ninety-six Wistar rats were randomly divided into sham-operated group, vascular dementia(VaD) model group and memantine-treated group. The vascular dementia rat model was established by permanent bilateral occlusion of the common carotid arteries. The changes of the expression of NR2B in hippocampus were measured by RT-PCR and the changes of the CaMK Ⅱ activities were determined by incorporation of r-~(32)P into histone. Results Compared with the sham rats, the level of NR2B in hippocampus increased significantly at 4 weeks after operation (P<0.05)and decreased at 8—16 weeks after operation (P<0.01). Total CaMK Ⅱ activity in hippocampus increased significantly at 4 weeks after operation (P<0.01) ,then dropped at 8 weeks after operation, and decreased significantly at 12, 16 weeks after operation (P<0.01). In memantine-treated group, at 4 weeks after operation, no statistical difference in the indexes mentioned above was found compared with the sham group, but at other time points, there were significant differences (P<0.05,P<0.01);besides, the level of NR2B was higher than that of VaD rats (P<0.05,P<0.01) at 8,12 weeks after operation, but total CaMK Ⅱ activitiy was similar to that of VaD rats. Conclusion The changes of CaMK Ⅱ activities are mainly mediated by NMDAR. Memantine can improve VaD rats' recognition by modulating the expression of NR2B,but its effect on CaMK Ⅱ activities is limited.