Endocannabinoid Targeting for Opioid Induced Respiratory Depression

项目摘要 意外过量死亡定义了阿片类药物的流行，尽管研究工作的替代手段， 解决阿片类药物使用障碍[1]和替代慢性疼痛治疗[2]。疾病控制中心 报告说，自1999年以来，有40多万人丧生，每天有130多人因意外过量而丧生 [3]的文件。这一数字将继续攀升，过度使用处方阿片类药物， 非法市场上更强的合成类阿片[4-6]。可能致命的阿片类药物过量可以成功地 纳洛酮，μ阿片受体拮抗剂，逆转，[7]，但随着疼痛患者人数的增加， 心脏病和糖尿病[2]以及非法阿片类药物市场中芬太尼的存在增加， 在缺氧发生之前，分配纳洛酮以逆转过量仍然很困难[8]。尝试 用新的阿片样化合物减少阿片样物质过量在很大程度上是不成功的[9]。因此 至关重要的是，未探索的预防阿片类药物诱导的呼吸抑制的治疗策略， 发现了 致命的阿片类药物过量通常归因于呼吸抑制，在此期间， 脑干中控制反射性吸气的前Bötzinger复合体（pBc）受到抑制。我们的试验数据表明 1）pBc含有内源性大麻素系统的组分，包括大麻素受体2 2）内源性大麻素系统（ECBS）脂质激活CB 2 R对正常呼吸至关重要 对照，和3）CB 2 R激动剂的外源性应用减轻吗啡诱导的呼吸抑制。 目前的建议将建立在这些发现的基础上，使用行为药理学，全身 体积描记术、成像、分子生物学、分析化学和基因编辑来检验假设， 在阿片样物质诱导的呼吸抑制期间，pBc中的内源性大麻素水平降低 （OIRD），并且施用脑渗透剂CB 2 R激动剂将减轻OIRD。目标1将测试CB 2 R 激动作为缓解OIRD的策略。每一个目标都包含了合理设计的研究， 通过纳入雄性和雌性小鼠的差异，应用于急性和慢性使用药物 和娱乐性阿片类药物（芬太尼、羟考酮和海洛因），以及多种化学类别的CB 2 R激动剂， 防止和逆转OIRD。目标2将确定内源性大麻素脂质，酶和受体的水平， 在OIRD期间的preBotzinger复合物（pBc）。成功完成拟议的研究将有助于 增强我们对正常呼吸期间和OIRD期间pBc内ECBS作用的了解 并验证靶向CB 2 R作为减少阿片类药物过量的安全治疗方法。

Project Summary Accidental overdoses fatalities define the opioid epidemic despite research efforts for alternative means to address Opioid Use Disorder [1] and alternative chronic pain therapies [2]. The Centers for Disease Control report over 400,000 lives lost since 1999 and more than 130 people lose their life to an accidental overdose daily [3]. This number will continue to climb with excessive utilization of prescription opioids and the presence of stronger synthetic opioids in the illicit market [4-6]. A potentially fatal opioid overdose can be successfully reversed with naloxone, mu opioid receptor antagonist, [7], but with the number of pain patients rising above heart disease and diabetes [2] and the increased presence of fentanyl in the illicit opioid market, adequate distribution of naloxone to reverse an overdose before oxygen deprivation occurs remains difficult [8]. Attempts to reduce opioid overdoses with novel opioid-like compounds have been largely unsuccessful [9]. Therefore, it is essential that unexplored therapeutic strategies to prevent opioid-induced respiratory depression be discovered. Fatal opioid overdoses are typically attributed to respiratory depression, during which neurons within the preBötzinger complex (pBc) in the brainstem that control reflexive inspiration are inhibited. Our pilot data suggest that 1) the pBc contains the components of the endocannabinoid system, including the cannabinoid receptor 2 (CB2R), 2) CB2R activation by endogenous cannabinoid system (ECBS) lipids is critical to normal respiration control, and 3) exogenous application of a CB2R agonist mitigates morphine induced respiratory depression. The current proposal will build upon these findings, using behavioral pharmacology, whole body plethysmography, imaging, molecular biology, analytical chemistry, and gene-editing to test the hypothesis that endogenous cannabinoid levels in the pBc are reduced during opioid induced respiratory depression (OIRD) and that administration of a brain penetrant CB2R agonist will mitigate OIRD. Aim 1 will test CB2R agonism as a strategy to mitigate to OIRD. Each aim contains rationally designed studies that include sex differences through inclusion of male and female mice, application to both acute and chronic use of medicinal and recreational opioids (fentanyl, oxycodone, and heroin), and multiple chemical classes of CB2R agonists to prevent and reverse OIRD. Aim 2 will determine levels of endocannabinoid lipids, enzymes, and receptors in the preBotzinger complex (pBc) during OIRD. Successful completion of proposed studies will serve to enhance our knowledge of the role of ECBS within the pBc in during normal respiration and during OIRD and validate targeting the CB2R as a safe treatment therapeutic to reduce opioid overdoses.