去松果体对大鼠学习记忆及大脑皮质胆碱能纤维的影响

Effects of pinealectomy on the learning and memory abilities and cholinergic fibers in cerebral cortex of rats

目的 探讨松果体功能减退致褪黑素 (MT)分泌减少对大鼠学习记忆及大脑皮质胆碱能纤维分布的影响。方法 将大鼠进行Y型迷宫测试 ,淘汰学习障碍的大鼠 ,将学习正常的大鼠随机分 2组 ,实验组手术摘除松果体 ,对照组给予假手术 ,饲养 40d后再行Y型迷宫测试 ,乙酰胆碱酯酶 (AChE)组织化学法测AChE。结果 实验组大鼠学习成绩由术前 (14.7± 5 .0 )次增加到术后(2 8.7± 2 .4)次 ,学习记忆能力明显低于术前自身及对照组 (13.8± 8.3)次 (P <0 .0 1) ,运动皮质、体感皮质第Ⅱ～Ⅳ层 ,海马CA1、CA2、CA3区辐状层、腔隙层、分子层和齿状回多形细胞层AChE阳性纤维密度明显低于对照组 (P <0 .0 1)。

Objective To investigate the effects of decreased melatonin (MT) secretion caused by declining function of pineal body on the learning and memory abilities and distridution of cholinergic fibers in the cerebral corteces of the rats. Methods After tested by Y type maze, the rats with normal study ablity were randomly divided into two groups including the experimental group with pinealectomy and the control group with sham operation. However, the rats with dysfunction of learning were eliminated. As soon as the rats of both the experiment and control groups were fed for 40 days, the Y type maze test was performed once more, and the samples of the brains were histochemical studied by acetycholinesterase (AChE), a marker of cholinergic fibres. Results The rats of the experimental group showed decreased achievement on learning and memory, because the stimulating times in the behaviour test increased from 14.7±5.0 of preoperation to 28.7±2.4 of postoperation. Comparing the experimental group of preoperation and the control group (13.8±8.3 ),the ability of learning and memory in the postoperation rats was worse obviously ( P <0.01),and the AChE positive fibers density was more significant decreased ( P <0.01) in Ⅱ～ Ⅳ layers of motor and somatosensory corteces, in the radiative, lacunaria and molecular layers of CA1,CA2,CA3 areas, and in the lamina multiformities of the dentate gyrus. Conclusion Pinealectomy of rats resulted in disorder of learning and memory and reduction of cholinergic fibers density in cerebrol cortex.