慢性脑缺血大鼠学习记忆损害与海马磁共振波谱分析

目的探讨慢性脑缺血对大鼠空间学习记忆功能及海马区神经细胞代谢物水平的影响及后两者的相关性。方法雄性10月龄SD大鼠30只,随机分为缺血组、假手术组和对照组,每组10只。行Morris水迷宫实验及质子磁共振波谱(~1H-MRS)扫描,计算左侧海马区N-乙酰天冬氨酸(NAA)/总肌酸(Cr)、胆碱复合物(Cho)/Cr的积分面积比值。结果缺血组大鼠定位航行的平均逃逸时间较假手术组和对照组明显延长,停留于平台所在区域的时间及穿越平台区域次数均较假手术组和对照组明显减少(P0.01)。缺血组大鼠左侧海马区Cho/Cr、NAA/Cr水平较假手术组和对照组明显降低(P0.05,P0.01)。各组大鼠左侧海马NAA/Cr、Cho/Cr水平与对应停留时间、穿越平台区域次数的变化趋势呈正相关。结论持续性低血流灌注可导致大鼠海马区神经元的功能代谢水平降低及学习记忆能力明显受损,海马区神经元的功能活性下降是认知障碍的重要机制之一。

Learning and memory impairment and magnetic resonance spectroscopy of hippocampus in aged rat with chronic cerebral ischemia

Objective To explore the effect of chronic cerebral ischemia on spatial learning and memory and hippocampal metabolite levels in aged rats.Methods Thirty male ten-month old SD rats were randomly divided into ischemia group,sham-operative group and control group of 10 rats each.The rats were tested by Morris water maze test and in vivo ~1H-MRS scan,then left hippocampal NAA/Cr and Cho/Cr levels were calculated.Results Escape latency of ischemia group rats was significantly longer than that of sham and control group rats (P < 0.01),retention time in target quadrant and frequency of crossing platform area were less in ischemia group than in sham and control groups (P < 0.01).Results from ~1H-MRS indicated that left hippocampal Cho/ Cr and NAA/Cr levels were lower in ischemia group than in sham and control groups (P < 0.05, P < 0.01).Left hippocampal NAA/Cr and Cho/Cr levels were positively correlated to retention time in target quadrant and frequency of crossing platform area in ischemia group,sham-operative group and control group.Conclusion Chronic cerebral ischemia results in spatial learning and memory deficit and metabolites levels descent of left hippocampus.The latter is possibly one of main mechanisms of cognitive handicap in aged rat.