去松果体后成年大鼠学习记忆及侧脑室室管膜下区神经干细胞增殖的变化

目的观察松果体切除对学习记忆及侧脑室室管膜下区(SVZ)神经干细胞增殖的影响。方法将30只成年健康雄性Sprague-Dawley大鼠随机分为非手术、假手术及去松果体组,每组大鼠10只。在建立动物模型16d后,连续5d测定大鼠在Morris水迷宫的学习记忆能力,继之用免疫组织化学方法观察SVZ的增殖细胞核抗原(PCNA)阳性细胞的变化。结果去松果体组大鼠在Morris水迷宫泳游的逃避潜伏期及在原平台象限游泳距离的百分比均较非手术组或假手术组大鼠的明显延长或减少(P<0.01)。去松果体大鼠SVZ的PCNA阳性细胞数也明显低于非手术组或假手术组大鼠(P<0.01)。结论本研究首次观察到,去松果体使体内褪黑素减少,可导致学习记忆功能及SVZ神经干细胞增殖能力出现相似的明显下降趋势,说明褪黑素是确保学习记忆及神经发生得以正常进行的重要激素之一;提示褪黑素可能直接通过作用于神经干细胞上的相应受体以及间接通过提高基底前脑胆碱能系统功能来促进神经干细胞增殖,进而提高嗅觉记忆功能。

Changes of learning and memory and that of proliferation of neural stem cells in the subventricular zone of lateral ventricle of adult rats after pinealectomy

Objective To investigate the effects of pinealeetomy on the learning and memory as well as on the proliferation of neural stem cells in the subventricular zone( SVZ) of the lateral ventricle. Methods Thirty adult male Sprague-Dawely rats were randomly divided into three groups, with ten rats per group: non-operated, sham-operated, and pinealectomized. After sixteen days of establishing the animal models, the rat performences in Morris water maze were detected for five consecutive days. Then the number of proliferating cell nuclear antigon immunoreactive ( PCNA-IR) cell nuclei in the SVZ was counted. Results Navigation tests showed that the escape latency for finding the platform during training trials of pinealectomized rats was significantly longer than that of non-operated or sham-operated rats ( P<0.01) . Probe tests revealed that pinealeetomized rats had much worse knowledge of the platform9s prcise location than non-operated or sham-operated rats did ( P<0.01) . Similarly, the mumber of PCNA-IR cell nuclei in the SVZ of pinealectomized rats was significantly lower than that in non-operated or sham-operated rats( P<0.01) . Conclusion Pinealectomy reduces the level of endogenous melatonin, and impairs the learming and memory processes as well as the proliferation of neural stem cells in the SVZ, indicating that melatonin plays an important role in maitaining the normal learning and memory as well as in augmenting the neurogenesis in SVZ; and that melatonin may promote the neurogenesis in SVZ via direct melatonin reeeptor-mediated mechanism and via indirect induction of the cholinergic system function of the basal forebrain, thereby enhancing olfactary memory.