【摘要】 用Ｍｏｒｒｉｓ水迷宫行为检测方法以青年组平均逃避潜伏期９５％和９９％正常值范围上限值为界将老年大鼠分为学习记忆正常组（老年正常组）和学习记忆减退组（老年减退组），以Ｈｅｄｒｅｅｎ等推荐的ＡＣｈＥ组织化学染色方法结合形态计量方法对各组大鼠的额、枕、内嗅皮质、海马ＣＡ１区多形层、腔隙分子层和齿状回分子层外带的胆碱能纤维密度进行分析，结果显示老年减退组较老年正常组、青年组各层（除枕叶外）ＡＣｈＥ阳性纤维数量均明显减少（Ｐ０．０５，Ｐ＜０．０１）。老年正常组与青年组相比各层阳性纤维数量有所减少，但除海马ＣＡ１区腔隙分子层差异显著外，其余差异均无显著性。相关分析结果表明大鼠各层ＡＣｈＥ阳性纤维数量与其平均逃避潜伏期呈负相关关系，与原平台象限游泳距离占总距离百分比呈正相关关系。本研究提示老年性学习记忆能力减退与新皮质、海马结构胆碱能纤维溃变密切相关。更多还原

【Abstract】 Senile learning and memory deficit may be associated with the cholinergic system’s degeneration of aged subjects’ forebrain. However,some paradoxical findings have emerged because of significant individual differences of learning and memory abilities between the aged animals. We attempted to reconcile certain paradoxes of age-related changes in cholinergic systems of the rat neocortex and hippocampal formation in the study. 34 aged (26-28 months)and 10 young(3 months) female Sprague-Dawley rats were used. In the Morris’ water maze task for studying spatial learning and memory,the rats were placed into a large circular pool (divided into 4 quadrants) of water from which they can escape by swimming onto a hidden platform (kept in a constant position in the middle of one quadrant). The rats were trained for 2 blocks of 4 trials on each day for 5consecutive days. On trial 5 of day 5 was replaced by a single "spatial probe" trial. The platform was removed from the pool . and the total swim distance in each quadrant was measured over 120 seconds. The aged rats were divided into the learning and memory-impaired group (old - impaired group) and learning and memory-nonimpaired group (old-nonimpaired group) according to the 99 and 95 percent normal range of the mean escape latency (swim time to find the platform) of the young rats (young control group) in the Morris’ water maze task. Old-impaired rats had longer escape latencies than both the young rats and the old nonimpaired rats. In"spatial probe" trial ,the swim path of old- impaired group was random in each quadrant ,the percentage swim distance in platform quadrant was 28. 7 % , and of the young and the old-nonimpaired group were 67. 7% and 50. 2% respectively,both of swim paths were converged in platform quadrant.A histochemical method for acetylcholinesterase(AChE) recommanded by Herded and a morphometry were used to assess the regional density of AChE-rich (putatively cholinergic) fibers in the frontal, occipital,entorhinal cortex,the polymorphous,and lacunosum-molecular layer of CA1 and the outer molecular layer of the dentate gyrus. A large number of AChE-positive fibers were observed in the rat neocortex and hippocampus, and displayed particular regional and laminar distributions according to the neocortex and hippocampus’s laminar pattern. The studied areas (except for occipital cortex) of old-impaired group contained a less density of AChE-positive fibers than the same areas of old-nonimpaired and young groups (P <0.05,P<0. 01). A slight decline in the density of AChE-positive fibers was observed in the examined areas of old-nonimpaired group. Regression analysis showed that the density of AChE-rich fibers of the examined areas (except occipital cortex) had a negative correlation with the mean escape latency, A positive correlation with the percentage swim distance in platform quadrant during the "spatial probe" trial. The results showed that it was very important that the same age’s old rats with different learning and memory abilities were divided into old-impaired group and old-nonimpaired group for studying the mechanism of senile learning and memory deficit,and that senile learning and memory deficit is associated with cholinergic fibers’degeneration of the neocortex and hippocampal formation.更多还原