Targeting Leptin Pathway to Treat Opioid-Induced Respiratory Depression

项目总结 根据CDC/NCHS National Val的数据，美国每天有130人死于阿片类药物过量 统计系统。与阿片类药物有关的主要死亡原因是阿片类药物引起的呼吸抑制。 (OIRD)。阿片类药物作用于脑干内的μ-阿片受体(MOR)，包括Prebőtzinger复合体和 腹式呼吸组降低呼吸频率。有几条证据表明，反复发作 在阿片类药物暴露期间，咽部阻塞和呼吸道通畅的丧失是OIRD的一个额外和主要的风险。 因此，OIRD是一种异质性疾病，包括两种独立的呼吸表型，受损 呼吸频率减慢和上呼吸道阻塞(UAO)表现为呼吸控制，类似于 阻塞性睡眠呼吸暂停。了解OIRD的这两种主要呼吸道表型对 药物开发。纳洛酮是MORS和其他阿片受体的竞争性拮抗剂。纳洛酮有 几十年来一直被用来逆转OIRD。它起效快，可用于鼻腔制剂。 然而，纳洛酮逆转了阿片类药物的镇痛作用，并可能导致急性戒断症状。此外, 它的半衰期很短。因此，新的长效治疗药物-解毒剂的识别和验证 对于OIRD，它不会逆转有益的MOR介导的止痛，也不会导致急性戒断症状， 是迫切需要的。我们的主要假设是瘦素可能作为OIRD的一种新的治疗方法。 全身(皮下和腹膜)注射瘦素刺激呼吸和上呼吸道功能 瘦素缺乏的肥胖/肥胖小鼠。而肥胖的人类和饮食诱导的肥胖(DIO)小鼠对 瘦素，抵抗瘦素的呼吸作用发生在血脑屏障水平，可以被绕过 如果瘦素是经鼻腔给药的(IN)。我们的初步数据显示：(1)吗啡抑制舌下肌 运动神经元与诱导OIRD；(2)Leptin逆转OIRD；(3)Leptin逆转阿片类药物诱导的OIRD 体外抑制HMN；(4)IN-Leptin的呼吸作用持续6小时以上，实质上 瘦素的作用时间比纳洛酮长；(5)瘦素不仅不会减弱，反而会促进吗啡的镇痛作用。我们的整体 假设OIRD可以通过鼻内注射瘦素来治疗，瘦素可以刺激呼吸 并通过恢复HMN活性同时维持MOR介导性来增加上呼吸道通畅性 止痛药。我们将在体内和体外评估瘦素途径作为治疗OIRD的潜在靶点。 模特们。具体目标1将检查是否单独使用瘦素(A)或与纳洛酮(B)联合治疗OIRD和 DIO和瘦雌雄小鼠的UAO。《特定目标2》将通过以下方式研究神经生物学机制 瘦素在体外治疗阿片类药物诱导的HMNS活性降低。该提案将确认瘦素是一种 治疗OIRD的新靶点，并将开发和验证新的OIRD体内和体外检测方法，以应对 NIH RFA-DA-20-025。

PROJECT SUMMARY Opioid overdose kills 130 people in the United States every day according to the CDC/NCHS National Vital Statistics System. The primary cause of death associated with opioids is opioid-induced respiratory depression (OIRD). Opioids act on μ-opioid receptors (MOR) within the brainstem, including the preBőtzinger complex and the ventral respiratory group to decrease respiratory rate. Several lines of evidence suggest that recurrent pharyngeal obstruction and loss of airway patency during opioid exposure is an additional and major risk in OIRD. Thus, OIRD is a heterogeneous condition, which includes two independent respiratory phenotypes, impaired control of breathing manifested by decreased respiratory rate, and upper airway obstruction (UAO) similar to obstructive sleep apnea. Understanding both of these two major respiratory phenotypes of OIRD is critical for drug development. Naloxone is a competitive antagonist of MORs and other opioid receptors. Naloxone has been used for decades to reverse OIRD. It has a rapid onset and it is available in the intranasal formulation. However, naloxone reverses opioid-induced analgesia and may cause acute withdrawal symptoms. In addition, it has short half-life. Therefore, the identification and validation of new long lasting therapeutic agents-antidotes for OIRD, which would not reverse the beneficial MOR mediated analgesia, or cause acute withdrawal symptoms, is urgently needed. Our overarching hypothesis is that leptin may serve as a novel treatment for OIRD. Systemic (subcutaneous and intraperitoneal) leptin administration stimulates breathing and upper airway function in lean and leptin deficient ob/ob mice. While obese humans and diet-induced obese (DIO) mice are resistant to leptin, resistance to the respiratory effects of leptin occurs at the blood brain barrier level and can be circumvented if leptin is administered intranasally (IN). Our Preliminary data show that: (1) morphine inhibits hypoglossal motoneurons (HMN) and induce OIRD in mice; (2) IN leptin can reverse OIRD; (3) leptin reverses opioid-induced HMN inhibition in vitro; (4) The respiratory effects of IN leptin last greater than 6 hours, which is substantially longer than naloxone; (5) IN leptin does not diminish, but rather facilitates, MOR analgesia. Our overall hypothesis is that OIRD can be treated by intranasal administration of leptin, which stimulates breathing and increases upper airway patency by restoring HMN activity while maintaining MOR-mediated analgesia. We will evaluate the leptin pathway as a potential target to treat OIRD using both in vivo and in vitro models. Specific Aim 1 will examine if IN leptin alone (A) or in combination with naloxone (B) treats OIRD and UAO in DIO and lean male and female mice. Specific Aim 2 will examine the neurobiological mechanisms by which leptin treats opioid-induced decreases in the activity of HMNs in vitro. The proposal will validate leptin as a novel target to treat OIRD and will develop and validate novel in vivo and in vitro assays for OIRD in response to the NIH RFA-DA-20-025.