基底前脑胆碱能系统与Orexin能系统参与调节慢性间歇低氧所致嗜睡

Chronic intermittent hypoxia (CIH) and sleep-awakening disorders are important pathophysiological features of obstructive sleep apnea syndrome (OSAS) and are closely related to the occurrence of excessive daytime sleepiness (EDS) and residual excessive sleepiness (RES) after CPAP therapy. However, the central mechanisms involved in EDS and RES remain unclear. It is known that the central cholinergic system and orexinergic neurons are important structures that regulate the sleep-wake cycle, and the basal forebrain is one of the central regulators of sleep activity. Otuyama et al. hypothesized that decreased central cholinergic activity may play a role in the pathophysiology of RES in patients with OSAS treated with CPAP, and that acetylcholine plays a large role in wakefulness physiology and its levels are reduced in sleepiness. So, in this study, we are going to test that hypothesis by providing experimental data demonstrating that the decline of cholinergic system function in the basal forebrain inhibits awakening and interacts with the orexin system. The goals of this study are:.1. To characterize behavioral changes and sleep using electroencephalography in CIH model rats after the microinjection of acetylcholine or receptor antagonist/agonist, orexin or receptor antagonist in the basal forebrain nucleus and the lateral ventricle..2. To investigate the effects of acetylcholine or receptor antagonists/agonists, orexin or receptor inhibitors on the spontaneous discharge activity of basal forebrain neurons using in vitro brain cell slices and whole cell patch clamp recording technique..3. To explore the behaviors and electrophysiology of CIH rats after electrically damaging the basal forebrain nucleus..4. To investigate the behavioral and electrophysiological changes of orexin gene-knocked out rats after CIH treatment using gene knockout techniques.

慢性间歇低氧（CIH）和睡眠-觉醒障碍是OSAS的重要病理生理特征，与白天过度嗜睡和CPAP治疗后残余嗜睡（RES）密切相关，但对于发生二者的中枢机制尚不清楚。基底前脑、中枢胆碱能与Orexin能系统是调控睡眠-觉醒周期的重要结构，Otuyama等提出“中枢胆碱能系统活性降低在RES的病理生理中起重要作用”这一假说。本研究将从多方面来验证该假说。.1．探讨在基底前脑核团和侧脑室微注射乙酰胆碱及受体拮抗剂/激动剂、Orexin及受体抑制剂对CIH模型大鼠行为学及睡眠的影响；.2．开展电生理学实验，以离体脑片和全细胞膜片钳记录技术，探讨乙酰胆碱及受体拮抗剂/激动剂、Orexin及受体抑制剂对基底前脑神经元自发放电活性的影响；.3．探讨电损毀基底前脑核团对CIH大鼠行为学及电生理学的影响；.4．利用基因敲除技术，探讨CIH处理后Orexin基因敲除大鼠的行为学及电生理学变化。

基于慢性间歇低氧（CIH）和睡眠-觉醒障碍是阻塞性睡眠呼吸暂停的重要病理生理特征，与白天过度嗜睡等认知功能损害密切相关，而有关中枢性机制尚不清楚，我们开展了本研究。主要研究内容为：利用动物行为学、电生理学、神经核团立体定位-微量注射、分子生物学以及基因技术等不同研究方法，探讨基底前脑核团中胆碱能系统以及Orexin能系统在调节CIH所致认知功能损害中的作用。以上均已按计划顺利进行。.主要研究结果包括二个方面：.1. 系统地探讨了基底前脑胆碱能神经元对慢性间歇低氧小鼠认知能力的影响。我们的研究发现，CIH可通过内质网应激、氧化应激和炎症反应等多种途径导致基底前脑胆碱能神经元受损，从而诱发小鼠认知功能障碍；而基底前脑胆经能系统在内质网应激、氧化应激和炎症反应中都发挥着重要作用；减轻对胆碱能神经元的损伤，可以恢复小鼠认知功能；作为乙酰胆碱上游递质的腺苷也在导致认知功能改变的各个环节中起重要调节作用。.2. 系统地探讨了Orexin能系统参与调节慢性间歇低氧所致嗜睡和认知能力损害的机制，包括：（1）探讨了Orexin A对CIH小鼠认知功能的影响及机制，发现CIH 可致小鼠认知功能障碍，而OXA可能通过抑制海马细胞凋亡和氧化应激而改善CIH诱导的小鼠认知功能障碍；（2）探讨了PKCα/ERK1/2信号通路参与Orexin A对慢性间歇低氧小鼠认知功能障碍的调控机制，发现CIH抑制小鼠海马OX1R而非OX2R的表达，其下游信号通路PKCα/ERK1/2参与OXA对CIH小鼠认知功能障碍的调控。（3）探讨了阻塞性睡眠呼吸暂停患者Orexin A昼夜水平变化与认知功能的相关性，结果显示，血浆OXA水平与OSA患者的认知功能和疾病严重程度存在相关性；日间血浆OXA水平下降对OSA患者认知功能障碍具有一定诊断价值。（4）探讨了Orexin-A对脑缺血后中枢神经系统炎症损伤的作用及其机制，我们的结果发现，经过OXA处理后，可以抑制卒中所诱导的缺血性炎症对中枢神经细胞的损伤，且该作用的机制是通过下调NF-κB信号通路而实现，提示OXA可作为减轻小鼠中风诱导的免疫抑制及减轻感染风险的潜在治疗靶点。