Regulation of opioid receptor function in trigeminal ganglion

描述（由申请人提供）：作用于5阿片受体（莫尔）的激动剂（例如吗啡及其类似物）是疼痛管理的主要药物;然而，存在严重的不良反应（例如依赖性）以及限制其使用的社会和法律的问题。因此，阿片类药物的外周镇痛作用引起了相当大的兴趣。然而，尽管阿片受体系统在感觉神经元中表达，但它们在大多数基础条件下功能不活跃，但当外周组织中存在一些刺激（炎症）时，它们变成功能有活性的。除莫尔外，4阿片受体（DOR）是药物作用的有吸引力的靶点，因为与莫尔活化相比，其副作用更少。但是，一般而言，4种激动剂促进镇痛的效力为弱至中度。在此，我们拟研究在原代培养得大鼠三叉神经节神经元和外周镇痛行为模型中，莫尔和DOR系统抑制腺苷酸环化酶活性和神经肽释放得功能能力得调节机制.我们的具体目标是：1）表征莫尔和DOR系统的功能能力的诱导和维持的动力学。我们将通过给予缓激肽（BK）、花生四烯酸（AA）和纳洛酮来描述诱导能力的时间过程以及诱导后能力的持续性。2)为了确定莫尔和DOR系统的变化，其是功能性能力发展的基础。在这个目的中，我们将确定阿片受体介导的G蛋白激活的启动诱导增加的机制。3)确定由纳洛酮和BK预处理诱导的莫尔和DOR受体系统的功能活性是否是由于组成性脱敏降低所致。我们假设莫尔/DOR受体系统以组成性脱敏状态存在，因此对激动剂无应答。用反向激动剂治疗应减少这种组成性脱敏，从而增强激动剂反应性。此外，用其他试剂（例如BK）引发也可通过减少组成性脱敏诱导感受态。4)探讨莫尔和DOR在镇痛行为测定中的功能能力。这一目标是对目标1-3基础工作的延伸。使用一种新开发的口面疼痛模型，我们将1）确定BK、AA和纳洛酮是否可以诱导莫尔和DOR系统的功能性能力，2）研究能力的时程，3）描述PKC 5在BK诱导的功能性能力的诱导中的作用，AA和纳洛酮，以及4）确定BK受体和PKC在疼痛炎症模型中介导功能能力的作用。这些实验将增加我们对初级感觉神经元中5和4阿片受体信号传导调节的理解，并可能导致治疗疼痛的新治疗方法。公共卫生关系：在过去的几年里，在C。 elegans、D.在囊泡融合和突触可塑性中起作用。当我们了解了不同的保守信号机制是如何控制突触可塑性的过程时，我们将对人类突触可塑性的过程和调控有基本的了解。果蝇作为一个模型系统的神经分泌研究为使用与哺乳动物突触释放和可塑性直接相关的基因操作和基因组学的不同方法提供了非凡的机会。

Description (provided by applicant): Agonists acting at the 5 opioid receptor (MOR) (e.g. morphine and its analogs) are the mainstay of pain management; however there are serious adverse effects (e.g. dependence) and social and legal issues which limit their use. Consequently there has been considerable interest in the peripheral analgesic effects of opioids. However, although opioid receptor systems are expressed in sensory neurons, they are functionally inactive under most basal conditions, but become functionally competent when some stimulus (inflammation) is present in the peripheral tissue. In addition to MOR, the 4 opioid receptor (DOR) is an attractive target for drug action since there are fewer adverse effects than with MOR activation. However, in general, the efficacy of 4 agonists to promote analgesia is weak to moderate. Here we propose to study mechanisms involved in the regulation of the functional competence of the MOR and DOR systems to inhibit adenylyl cyclase activity and neuropeptide release in primary cultures of rat trigeminal ganglion neurons and in behavioral models of peripheral analgesia. Our specific aims are: 1) To characterize the kinetics of induction and maintenance of functional competence of MOR and DOR systems. We will delineate the time course for induction of competence, and the persistence of competence after induction, by administration of bradykinin (BK), arachidonic acid (AA) and naloxone. 2) To determine the changes in the MOR and DOR systems which underlie the development of functional competence In this aim, we will determine the mechanism for the priming-induced increase in opioid receptor-mediated G protein activation. 3) To determine if functional competence of MOR and DOR receptor systems induced by naloxone and BK pre-treatment is due to reduced constitutive desensitization.. We hypothesize that the MOR/DOR receptor systems exist in a constitutively desensitized state thus are non-responsive to agonist. Treatment with inverse agonists should reduce this constitutive desensitization leading to enhanced agonist responsiveness. Also priming with other agents (e.g. BK) may induce competence by reducing constitutive desensitization. 4) To investigate the functional competence of MOR and DOR in behavioral assays of analgesia. This aim provides a translational extension of the foundation work of Aims 1-3. Using a newly developed model of orofacial pain, we will 1) determine if functional competence of the MOR and DOR systems can be induced by BK, AA, and naloxone, 2) investigate the time course of competence, 3) delineate the role of PKC5 in induction of functional competence induced by BK, AA and naloxone and 4) determine the role of BK receptors and PKC in mediating functional competence in an inflammatory model of pain. These experiments will increase our understanding of the regulation of 5 and 4 opioid receptor signaling in primary sensory neurons and may lead to novel therapeutic approaches for the treatment of pain. PUBLIC HEALTH RELEVANCE: In the last few years many mutations in different genes have been isolated in C. elegans, D. Melanogaster and mice which plays role in vesicle fusion and synaptic plasticity. Fundamental insights into the processes and regulation of human synaptic plasticity will occur when we understand how different conserved signaling mechanism controls this process. The neurosecretion study of Drosophila as a model system provides extraordinary opportunities to use different methods of gene manipulation and of genomics with direct relevance to mammalian synaptic release and plasticity.