不同时长运动预处理对血管性痴呆大鼠脑血流量及小胶质细胞活化相关蛋白的影响

Effects of different duration of exercise preconditioning on cerebral blood flow and microglia activation related proteins in rats with vascular dementia

目的:探讨不同时长运动预处理对血管性痴呆大鼠脑血流量变化及小胶质细胞活化相关蛋白的影响。方法:选用60只SPF级SD雄性大鼠,采用双侧颈总动脉永久性结扎法制备血管性痴呆大鼠模型,随机分为模型组、假手术组、运动预处理4周模型组、运动预处理4周假手术组、运动预处理2周模型组及运动预处理2周假手术组,每组10只。运动预处理4周大鼠在造模前每周行5次中等强度不负重游泳训练30min,持续4周,而运动预处理2周大鼠持续2周。利用Morris水迷宫检测大鼠空间学习记忆能力、激光散斑成像技术检测各组大鼠造模前后不同时间点脑血流变化及侧支循环开放情况、Western Blot技术检测海马TLR4及Iba1蛋白表达情况。结果:与假手术组、运动预处理2周假手术组相比,运动预处理4周假手术组、模型组、运动预处理4周模型组及运动预处理2周模型组大鼠平均逃避潜伏时延长(P<0.05)。与运动预处理4周假手术组相比,模型组、运动预处理4周模型组大鼠平均逃避潜伏时延长(P<0.05)。与模型组、运动预处理4周模型组相比,运动预处理2周模型组大鼠平均逃避潜伏时缩短(P<0.05)。重复测量方差分析简单效应提示造模前、造模后2h、造模后3d及造模后7d各组间平均脑血流量差异具有显著性意义(P<0.05)。模型组、运动预处理4周模型组及运动预处理2周模型组时间因素对平均脑血流量的简单效应具有显著性意义(P<0.01)。对各组大鼠侧支循环开放进行观察,相较于模型组,于运动预处理2周模型组观察到更少的微血管直径减少(P<0.05)。与假手术组、运动预处理4周假手术组及运动预处理2周假手术组相比,模型组Iba1、TLR4蛋白表达明显上升(P<0.01),与模型组相比,运动预处理2周模型组Iba1、TLR4蛋白表达下降(P<0.05)。结论:中等强度运动预处理2周可改善血管性痴呆大鼠学习记忆能力,运动预处理4周对学习记忆能力改善效应不明显,其机制可能与改善脑血流状态以及抑制小胶质细胞活化有关。

Objective:To explore the effects of different duration of exercise preconditioning on changes in cerebral blood flow and microglia activation related proteins in rats with vascular dementia.Method:Sixty SPF SD male rats were used to prepare vascular dementia rat models by permanent ligation of bilateral common carotid arteries.They were randomly divided into the model group,sham-operated group,exercise preconditioning 4-week model group,exercise preconditioning 4-week sham-operated group,exercise preconditioning 2-week model group and exercise preconditioning 2-week sham-operated group,with 10 rats in each group.The exercise preconditioning 4-week rats received 30 minutes of moderate intensity non-weight-bearing swimming training 5 times a week for 4 weeks before modeling,while the exercise preconditioning 2-week rats received the same training for 2 weeks.Morris water maze was used to detect the spatial learning and memory ability of rats,laser speckle imaging technique was used to observe the changes of cerebral blood flow and the opening of collateral circulation of rats at different time point before and after the modeling,and Western Blotting was used to detect the expression of TLR4 and Iba 1 protein in hippocampus.Result:Compared with the sham-operated group and the exercise preconditioning 2-week sham-operated group,the average escape latency time of rats in the exercise preconditioning 4-week sham-operated group,the model group,the exercise preconditioning 4-week model group and the exercise preconditioning 2-week model group was significantly prolonged(P<0.05).Compared with the exercise preconditioning 4-week sham-operated group,the average escape latency time of rats in the model group and the exercise preconditioning 4-week model group was significantly prolonged(P<0.05).Compared with the model group and exercise preconditioning 4-week model group,the average escape latency time of rats in exercise preconditioning 2-week model group was significantly decreased(P<0.05).The simple effect of repetitive measurement deviation analysis suggested that the average cerebral blood flow before modeling,2h after modeling,3d after modeling and 7d after modeling was statistically significant between the groups(P<0.05).The simple effect of time factor on average cerebral blood flow of the model group,the exercise preconditioning 4-week model group and the exercise preconditioning 2-week model group was statistically significant(P<0.01).The opening of collateral circulation of rats in each group was observed.Compared with the model group,less reduction in microvessel diameter was observed in the exercise preconditioning 2-week model group(P<0.05).Compared with the sham-operated group,the exercise preconditioning 4-week sham-operated group and the exercise preconditioning 2-week sham-operated group,Iba1 and TLR4 protein expressions in the model group were significantly increased(P<0.01).Compared with the model group,Iba1 and TLR4 protein expressions in the exercise preconditioning 2-week model group were decreased(P<0.05).Conclusion:Moderate intensity exercise preconditioning for 2 weeks can improve the learning and memory ability of vascular dementia rats,but exercise preconditioning for 4 weeks has no obvious effect on the improvement of learning and memory ability.The mechanism may be related to the improvement of cerebral blood flow status and the inhibition of microglia activation.