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.