重复肢体远隔缺血适应对慢性脑低灌注大鼠空间学习记忆的影响及机制

摘要

Objective To explore the effect and mechanism of repeated limb remote ischemic conditioning (LRIC) on spatial memory and learning in chronic cerebral hypoperfusion rats.Methods Sixty male SD rats were selected and randomly divided into the sham group, model group, single LRIC group, and multiple LRIC group.The rats in the latter three groups underwent bilateral carotid artery occlusion (2VO) to establish chronic cerebral hypoperfusion models, and the bilateral carotid arteries of rats in the control group were only separated without ligation.Three days after surgery, rats in the single LRIC group received LRIC just once, the detailed method was that ribbon gauzes were used to ligature hind limbs for occluding the femoral artery, ligating for 10 min, loosening for 10 min, and three circles each time.Rats in the multiple LRIC group received LRIC once a day for 6 w.Four weeks after LRIC was finished, Morris water maze test was used to test escape latency and target quadrant percentage, cerebral blood flow of hippocampal CA1 region was measured with laser Doppler, and the ultrastructure of axons and blood vessels in hippocampal CA1 region was observed by electron microscopic.Results Escape latency of the sham group, multiple LRIC group was shorter than that of the model group and single LRIC group, but the target quadrant percentage was higher than that of the model group and single LRIC group (P<0.05 or P<0.01).The relative cerebral blood flow of hippocampal CA1 region in the sham group, model group, single LRIC group, and multiple LRIC group was 100%, 61.3%±11.7%, 59.5%±13.1%, and 80.2%±14.6%, respectively.The relative cerebral blood flow of the sham group and multiple LRIC group was higher than that of the model group and single LRIC group (all P<0.05).Endothelium was not smooth;thickening of the basement membrane, obvious peripheral edema, axonal fracture, and plate separation were observed in CA1 region of the model group;the changes mentioned above alleviated significantly in the multiple LRIC group (blood vessels and axons changes were not tested because there was no significant difference in spatial learning memory and cerebral blood flow between the single LRIC group and model group).Conclusion Repeated LRIC can improve cognitive impairment caused by chronic cerebral blood flow hypoperfusion by increasing blood supply in hippocampus and inhibiting microvascular injury in hippocampus.%目的 探讨重复肢体远隔缺血适应(LRIC)对慢性脑低灌注大鼠空间学习记忆的影响及作用机制.方法 选择健康雄性SD大鼠60只,随机均分为假手术组、模型组、单次LRIC组、多次LRIC组,后三组采用双侧颈总动脉结扎(2VO)法建立大脑低灌注损伤模型,假手术组仅分离双侧劲总动脉不予结扎.术后3天时,单次LRIC组进行1次LRIC,具体方法为采用纱布条绑扎双侧下肢完全阻断股动脉血流,绑扎10 min,松开10 min,每次3个循环;多次LRIC组每天进行LRIC 1次,连续6周.LRIC结束后4周采用Morris水迷宫试验检测逃避潜伏期及目标象限时间百分比,激光多普勒血流仪检测海马CA1区脑血流,电镜观察海马CA1区轴索及血管的超微结构.结果 假手术组、多次LRIC组逃避潜伏期均短于模型组和单次LRIC组,目标象限时间百分比均长于模型组和单次LRIC组,组间比较P<0.05或<0.01.假手术组、模型组、单次LRIC组、多次LRIC组海马CA1区相对脑血流分别为100%、(61.3±11.7)%、(59.5±13.1)%、(80.2±14.6)%,假手术组、多次LRIC组均高于模型组和单次LRIC组(P均<0.05).模型组海马CA1区血管内皮不光滑、基底膜增厚、周围明显水肿,轴索明显断裂、板层分离;多次LRIC组上述改变明显减轻.结论 重复LRIC可改善慢性脑血流低灌注导致的认知功能障碍;增加海马区血供、抑制海马区微血管损伤可能是其作用机制.