Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
Sleep. 2013 Aug 1;36(8):1129-38. doi: 10.5665/sleep.2870.
Narcolepsy is caused by selective loss of the orexin/hypocretin-producing neurons of the hypothalamus. For patients with narcolepsy, chronic sleepiness is often the most disabling symptom, but current therapies rarely normalize alertness and do not address the underlying orexin deficiency. We hypothesized that the sleepiness of narcolepsy would substantially improve if orexin signaling were restored in specific brain regions at appropriate times of day.
We used gene therapy to restore orexin signaling in a mouse model of narcolepsy. In these Atx mice, expression of a toxic protein (ataxin-3) selectively kills the orexin neurons.
To induce ectopic expression of the orexin neuropeptides, we microinjected an adeno-associated viral vector coding for prepro-orexin plus a red fluorescence protein (AAV-orexin) into the mediobasal hypothalamus of Atx and wild-type mice. Control mice received an AAV coding only for red fluorescence protein. Two weeks later, we recorded sleep/wake behavior, locomotor activity, and body temperature and examined the patterns of orexin expression.
Atx mice rescued with AAV-orexin produced long bouts of wakefulness and had a normal diurnal pattern of arousal, with the longest bouts of wake and the highest amounts of locomotor activity in the first hours of the night. In addition, AAV-orexin improved the timing of rapid eye movement sleep and the consolidation of nonrapid eye movement sleep in Atx mice.
These substantial improvements in sleepiness and other symptoms of narcolepsy demonstrate the effectiveness of orexin gene therapy in a mouse model of narcolepsy. Additional work is needed to optimize this approach, but in time, AAV-orexin could become a useful therapeutic option for patients with narcolepsy.
发作性睡病是由下丘脑产生食欲素/下丘脑分泌素神经元选择性丧失引起的。对于发作性睡病患者来说，慢性嗜睡通常是最具致残性的症状，但目前的治疗方法很少能使警觉性正常化，也不能解决潜在的食欲素缺乏问题。我们假设，如果在一天中的适当时间在特定的脑区恢复食欲素信号，发作性睡病的嗜睡症状将大大改善。
我们使用基因治疗来恢复发作性睡病小鼠模型中的食欲素信号。在这些 Atx 小鼠中，一种毒性蛋白（ataxin-3）的表达选择性地杀死了食欲素神经元。
为了诱导食欲素神经肽的异位表达，我们将编码前食欲素加红色荧光蛋白（AAV-食欲素）的腺相关病毒载体微注射到 Atx 和野生型小鼠的中脑基底部。对照小鼠接受仅编码红色荧光蛋白的 AAV。两周后，我们记录了睡眠/觉醒行为、运动活动和体温，并检查了食欲素表达模式。
用 AAV-食欲素拯救的 Atx 小鼠产生了长时间的清醒期，并表现出正常的觉醒昼夜节律模式，在夜间的前几个小时内，清醒时间最长，运动活动量最大。此外，AAV-食欲素改善了 Atx 小鼠快速眼动睡眠的定时和非快速眼动睡眠的巩固。
这些在嗜睡和发作性睡病其他症状方面的显著改善表明，食欲素基因治疗在发作性睡病小鼠模型中是有效的。需要进一步优化这种方法，但随着时间的推移，AAV-食欲素可能成为发作性睡病患者的一种有用的治疗选择。
