CaMK Ⅱ在跑步机训练改善帕金森病模型小鼠记忆功能中的作用

Role of CaMK II in treadmill training to improve memory function of Parkinson disease mice model

目的研究钙离子／钙调蛋白激酶Ⅱ（CaMKⅡ）在跑步机训练改善帕金森病（PD）模型小鼠记忆功能中的分子机制，为PD的治疗提供一个新的思路。方法将6-羟基多巴胺立体定向注射至小鼠左侧纹状体内制备偏侧PD小鼠模型，利用圆柱体实验筛选PD模型。将造模成功的PD小鼠（n=32）随机分为PD非跑步机训练组（PD＋no—Ex组，n=8）、低速跑步机训练组（PD＋Low—Ex，n=8）、中速跑步机训练组（PD＋Medium—Ex，n=8）和高速跑步机训练组（PD＋High—Ex，n=8），并设Sham组（n=8，在相同部位注射生理盐水）作为对照。利用Morris水迷宫实验观察各组小鼠的学习记忆能力，并对其行为学结果进行分析评价，选取Sham组、PD＋no—Ex组及PD＋Low～Ex组海马组织，利用Western blot检Nd,鼠海马中环磷腺苷效应元件结合蛋白（CREB）、酪氨酸羟化酶（TH）、细胞外信号调节蛋白激酶1／2（ERK 1／2）和CaMKⅡ的磷酸化水平。结果Morris水迷宫定位航行实验结果表明各组小鼠的平均逃避潜伏期随着训练时间的延长呈逐渐下降趋势，低中高速跑步机训练都有利于PI]小鼠记忆功能的恢复（P〈0．05），但低速跑步机训练组小鼠改善得更明显（P〈O．05）。空间探索实验结果则表明，与Sham组比较，PD＋no—Ex组小鼠穿越平台次数明显减少，差异有统计学意义沪〈0．05）；与PD＋no—Ex组比较，不同速度跑步机训练组小鼠穿越平台次数明显增加，差异有统计学意义护〈0．05）。Western blot结果显示，与Sham组比较，PD＋no—Ex组磷酸化CREB、ERK 1／2、CaMKU及TH水平明显降低，差异均有统计学意义（P〈0．05）；与PD＋no—Ex组比较，PD＋Low—Ex组上述指标明显升高，差异均有统计学意义护〈0．01）。结论低速跑步机训练对PD模型小鼠学习记忆能力的改善作用更显著，其可能是通过上调海马中蛋白激酶A（PKA）介导的信号转导通路，从而改善PD小鼠的认知功能。

Objective To investigate the molecular mechanism of calcine kinase Ⅱ （CaMKⅡ） in improving the memory function of mice with Parkinson disease （PD）, and to explore the possible mechanism underlying this effect, which will provide a new idea to treat PD. Methods 6-OHDA was stereotactically injected into the left striatum of mouse to prepare the lateral PD mouse model. Then the valid PD model was selected by cylinder test. All valid PD （n=32） mice were divided into four groups： PD＋ no-Ex group （n=8）, PD＋Low-Ex group （n=8）, PD＋Medium-Ex group （n=8） and PD＋High-Ex （n=8）. Another group of sham- operated mice were involved as control （n=8, injection of saline at the same site）. Through the analysis and evaluation of their behavioral results, the hippocampus of mice in sham-operated group, PD＋no-Ex group and PD ＋ Low-Ex group were selected for Western blot to detect the phosphorylation levels of cAMP-response element binding protein （CREB）, the extracellular signal-regulated kinase 1/2 （ERK1/2）, Tyrosine hydroxylase （TH） and calmodulin kinase Ⅱ （CaMK Ⅱ）. Results The navigation test of Morris water maze showed that the mean escape latency of each group was gradually decreased with the prolongation of training time. Differentspeed of treadmill exercise all improved the memory of mice especially the low speed exercise （P 〈 0.05）. In addition, spatial probe test showed that compared with mice in sham-operated group, the number of times through the platform were decreased in mice of PD ＋ no-Ex group, and the difference was statistically significant （P 〈 0.05）. Western blot results showed that the levels of phosphorylated CREB, ERK1/2, CaMKII and TH were decreased in PD mice compared to sham-operated mice （P 〈 0.05）. However, compared with PD＋no-Ex group, the indicators above in PD＋Low-Ex group increased significantly, and the difference was statistically significant （P 〈 0.01）. Conclusions Low-exercise training was effective to improve memory in PD mice, which is because that low-exercise training could enhance the activity of PKA pathway, so as to improve the cognition function of PD mice.