细胞型朊蛋白PrPC在睡眠剥夺与AD发病间发挥关联作用的机制研究

The incidence of sleep disorders and Alzheimer's diseases (AD)are increasing for decades. Moreover,both would contribute to dramatic cognitive impairment, and place an heavy burden on family and society. Previous studies on relation between them always focus on the occurrence of sleep disorders in AD patients.Rencent research indicate that sleep disorder may be an important cause for occurence and progression of AD,as sleep deprivation could lead to increased Aβ in Cerebro-Spinal Fluid（CSF) as well as accelerated amyloid deposition,however the mechanism is still vague.In an effort to identify novel linking mechanism between sleep deprivation and AD, we found that REM-sleep deprivation(REMSD)lead to downregulation in PRPC expression and CREB phosphorylationin in rat hipocampus. It was known that cell-type prion protein PrpC can bind to Aβ precursor protein(APP) and inhibit β-secretase(BACE1)activity, and recently it is considered as a high-affinity neuronal receptor for Aβ oligomers also and is necessary in mediating the toxicity. On the other hand, CREB was thought as a 'molecular switch' in memory and cell survival.Therefore, we suggested that PrpC likely to be a novel linker between sleep deprivation and AD. By using molecular biology, cell biology and behavioral study methods, we would explore whether PrpC was invlved in Aβpathology， neuronal apotosis and recognition impairment， which would provide with experiment evidence for the impact of sleep deprivation on AD.

近年来睡眠障碍和AD的发病率不断攀升，二者都严重影响患者的认知行为能力，导致严重的家庭－社会负担。既往对二者间的关联的认识多集中在AD患者发生睡眠障碍的临床报道和基础研究。近年来，有研究提示睡眠障碍也可能是AD发生和进展的重要诱因，睡眠剥夺可能促使AD大鼠脑脊液Aβ的产生增加和神经元Aβ沉积增多，而具体机制还不明确。我们的研究中发现REM睡眠剥夺(REMSD)后大鼠海马PrpC显著降低，敲减PrpC导致海马神经元CREB磷酸化减少。由于PrpC可能与Aβ的产生和信号转导相关，而CREB是细胞记忆的重要"分子开关"且与细胞存活密切相关。据此我们提出PrpC可能是REMSD与AD间关联的重要分子机制，应用分子生物学，细胞生物学与行为学研究方法对Prpc参与Aβ代谢与神经元凋亡和认知功能障碍的信号转导进行研究，为明确睡眠对AD的作用提供理论证据。

睡眠障碍与Alzheimer病（AD）都影响认知行为，造成家庭社会负担。以往只关注AD导致的睡眠障碍或关注睡眠障碍影响认知表现。但近年研究发现，睡眠障碍是AD发病有关，睡眠剥夺影响淀粉样蛋白（Aβ）代谢和沉积，二者有关联。细胞型朊蛋白（PRPC）正常中枢神经丰富表达，有研究提示PRPC可能是二者间关联分子。.采用改良多平台法剥夺快速眼动睡眠、Morris水迷宫评估空间记忆、蛋白质印迹法检测PrPC表达、酶联免疫吸附法检测Aβ表达，原代培养海马神经元、RNA干扰技术沉默PrPC等方法，研究PRPC参与认知调节的机制。.成年小鼠明暗周期下6个时点取海马、皮层样本，Halberg余弦分析显示，PrPC在皮层、Aβ在海马表达都有昼夜节律性(P<0.05)；大鼠睡眠剥夺后，空间记忆受损，穿越平台次数(3.17±0.95)较笼养组(7.17±0.95)和水槽对照组(6.50±0.62)明显减少(P<0.05)，平台接近平均值(mm)睡眠剥夺组(711.744±33.99)较笼养(592.32±31.31)和水槽对照组(580.86±11.36)明显增大(P<0.05)。睡眠剥夺组海马PrPc表达(0.33±0.10)较笼养(1.01±0.33)和水槽对照组(0.96±0.27)明显下调(P<0.05)。沉默PrPc导致原代海马神经元轴突(um)延伸障碍，感染组(326.28±12.53)较未感染组(555.00±30.43)和感染阴性组(558.70±23.10)轴突明显变短(P<0.05)。.正常脑组织PrPC和Aβ表达有昼夜节律特征，睡眠剥夺后PrPC表达下调、Aβ上调。PrPC介导海马新生神经元轴突延伸障碍，可能是睡眠剥夺后认知障碍的潜在机制之一，表明睡眠障碍在AD发病中起作用。PRPC调节Aβ代谢，参与AD发病发展，可能是AD潜在治疗靶点之一，调整其表达与功能，有望开辟治疗新领域。