Treatment of Sleep Apnea by Targeting Leptin Signaling

阻塞性睡眠呼吸暂停(OSA)是由上呼吸道肌肉丧失引起的复发性上呼吸道阻塞。 睡眠时的音调。目前还没有针对阻塞性睡眠呼吸暂停综合征的药物治疗。迫切需要一种可以逆转 上呼吸道功能中的神经肌肉缺陷。我们的努力主要集中在瘦素，一种由脂肪细胞产生的 抑制食欲、加快新陈代谢、促进呼吸控制的荷尔蒙。我们有 此前有报道称，肥胖的小鼠会患上阻塞性睡眠呼吸暂停综合症，而瘦素可以对其进行治疗。我们的初步结果显示 (1)瘦素受体(LepRb)缺陷db/db小鼠发生阻塞性睡眠呼吸暂停(OSA)，这一现象被 LepRb在下丘脑背内侧核表达后脑室内的瘦素(db/db-LepRb- DMH小鼠)；(2)饮食诱导肥胖(DIO)LepRb-CRE小鼠兴奋性激活后OSA改善 表达在LepRb+神经元上的设计师受体被设计师药物(DREADD)特异性激活 孤束核(NTS)；(3)舌下运动神经元不表达LepRb，但表达LepRb+神经元 向舌下核投射和光发生刺激LepRb+突触增加舌下神经 LepRb-ChR2小鼠运动神经元的活动；(4)DMH和NTS内的LepRb+神经元为黑素皮质素4受体 (MCR4)阳性。我们的假设是，瘦素作用于DMH和NTS中的LepRb+神经元，以维持 睡眠时呼吸道通畅。特定目标1将检验这样一个假设，即LepRb+神经元在脑内的激活 DMH可减轻上呼吸道阻塞和阻塞性睡眠呼吸暂停。我们提出(A)LepRb+DMH的选择性刺激 脑室注射瘦素对db/db-LepRb-DMH小鼠神经元的影响及DIO-LepRb-Cre对兴奋性DREADDS的激活作用 小鼠将改善上呼吸道通畅并治疗OSA；(B)CRE敲除DMH神经元中的LepRb+ 重组酶在DIO LepRb FLOX/FLOX小鼠中的表达及对DIO LepRb-CRE小鼠这些神经元表达的抑制 抑制性DREADDS将降低上呼吸道通畅性并加重OSA；(C)瘦素对OSA的影响 MC4R阻滞剂可使db/db-LepRb-DMH小鼠减毒。《特定目标2》将考察 瘦素在NTS中对阻塞性睡眠呼吸暂停综合征的作用，除我们的干预外，将按SA1A-C设计 将以NTS为目标。特殊目标3将检查LepRb+神经元之间的突触联系，这些神经元起源于 DMH和NTS都投射到舌下运动神经元并在其上突触。我们建议双方 DMH和NTS LepRb+神经元与舌下运动神经元的联系和(A)的光发生刺激 DMH和(B)NTS LepRb通道视紫红质(ChR2)表达的神经元和纤维激活舌下神经 运动神经元。在SA1-2中，我们将采用我们实验室开发的一整套生理测量方法 包括多导睡眠图、动态磁共振成像和肥胖男性的咽部塌陷测量 和雌性老鼠。在SA3中，光遗传工具在靶向LepRb神经元群体中的选择性表达将 可与膜片钳电生理学结合应用于体外脑片。我们的提案将确定 瘦素依赖机制可作为治疗阻塞性睡眠呼吸暂停综合征的靶点。

Obstructive sleep apnea (OSA) is recurrent upper airway obstruction caused by a loss of upper airway muscle tone during sleep. There is no pharmacotherapy for OSA. There is an urgent need for therapeutics that reverse neuromuscular defects in upper airway function. Our efforts have focused on leptin, an adipocyte-produced hormone, which suppresses appetite, increases metabolic rate, and up-regulates control of breathing. We have previously reported that obese mice develop OSA, which was treated by leptin. Our preliminary results show that (1) leptin receptor (LepRb) deficient db/db mice develop OSA, which was abolished by intracerebroventricular (ICV) leptin after expression of LepRb in the dorsomedial hypothalamus (db/db-LepRb- DMH mice); (2) OSA improved in diet induced obese (DIO) LepRb-Cre mice upon activation of excitatory Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) expressed in LepRb+ neurons of the nucleus of the solitary tract (NTS); (3) hypoglossal motoneurons do not express LepRb, but LepRb+ neurons project to the hypoglossal nucleus and photogenetic stimulation of LepRb+ synapses increased hypoglossal motoneuron activity in LepRb-ChR2 mice; (4) LepRb+ neurons in DMH and NTS are melanocortin 4 receptor (MCR4) positive. Our hypothesis is that leptin acts on LepRb+ neurons in DMH and NTS to maintain upper airway patency during sleep. Specific Aim 1 will test the hypothesis that activation of LepRb+ neurons in the DMH alleviates upper airway obstruction and OSA. We propose that (A) selective stimulation of LepRb+ DMH neurons by ICV leptin in db/db-LepRb-DMH mice and by activation of excitatory DREADDs in DIO LepRb-Cre mice will improve upper airway patency and treat OSA; (B) knockout of LepRb+ in DMH neurons by Cre recombinase in DIO LepRb flox/flox mice and inhibition of these neurons in DIO LepRb-Cre mice expressing inhibitory DREADDs will decrease upper airway patency and aggravate OSA; (C) effects of leptin on OSA in db/db-LepRb-DMH mice will be attenuated by MC4R blockers. Specific Aim 2 will examine mechanisms of leptin’s action in the NTS on OSA in vivo and will be designed as SA1 A-C with exception that our interventions will target NTS. Specific Aim 3 will examine synaptic connections between LepRb+ neurons, originating from both the DMH and NTS, that project to and synapse upon hypoglossal motoneurons. We propose that both DMH and NTS LepRb+ neurons connect to hypoglossal motoneurons and that optogenetic stimulation of (A) DMH- and (B) NTS LepRb-channelrhodopsin (ChR2) expressing neurons and fibers activates hypoglossal motoneurons. In SA1-2, we will employ a full arrays of physiological measurements developed in our laboratory including polysomnograms, dynamic MR imaging, and pharyngeal collapsibility measurements in obese male and female mice. In SA3, selective expression of optogenetic tools in targeted LepRb neuronal populations will be employed in combination with patch clamp electrophysiology in brain slices ex vivo. Our proposal will identify leptin-dependent mechanisms which can be targeted for treatment of OSA.