铅致大鼠记忆受损及海马AChE阳性纤维的改变

本实验采用明暗箱被动回避反应和穿梭箱条件性回避反应测定， 探讨了铅对大鼠学习与记忆的损害作用。应用酶组织化学方法观察了铅致大鼠海马的结构改变。行为测定显示， 大鼠饮１０％ 醋酸铅水液之前和之后， 其进洞潜伏期 （ｓｔｏｐｔｈｒｏｕｇｈ ｌａｔｅｎｃｙ， ＳＴＬ） 与对照组无明显差异， 而饮醋酸铅水液后， 其条件性回避反应率（ｃｏｎｄｉｔｉｏｎｅｄ ａｖｏｉｄａｎｃｅ ｒｅｓｐｏｎｓｅ ｒａｔｅ， ＣＡＲＲ） 较对照组明显下降（ｄ４－ ｄ１４， Ｐ＜ ００５）， 表明大鼠饮醋酸铅水液后长时记忆不受影响， 而短时记忆受到损伤。组织化学反应染色显示实验组海马腔隙分子层内ＡＣｈＥ阳性纤维面积百分数较对照组明显减少（Ｐ＜ ００５）， 且纤维变细， 膨体减少。推测铅致大鼠短时记忆能力下降， 可能与海马内胆碱能纤维减少有关。

EXPERIMENTAL OBSERVATION ON IMPAIRMENT OF LEARNING AND MEMORY AND THE CHANGE OF AchE POSITIVE FIBERS IN THE HIPPOCAMPUS OF LEAD EXPOSED RATS

The impairment of learning and memory of lead exposed rats was evaluated by examining the passive avoidance response and conditioned avoidance response. We observed the morphometric changes in the hippocampus of lead exposed rats with AchE cytochemical methods. Before and after the experimentel group drank drinking lead acetate solution (1.0%), the stop through latency (STL) of two groups was similar. But the conditioned avoidance response rate (CARR) decreased obviously (d4 d14,P<0 05) in the experimental group. It suggested that the short term, not the long term, learning and memory function of the experimental group was impaired. The surface percent of AChE positive fibers in hippocampal stratum lacunosum and moleculare of lead exposed rats decreased (P<0 05). The fibers became thinner, and the varicosities declined. It indicated that lead couldresult in the damage of the morphology and the function of hippocampus.