Adenylyl Cyclase GBetaGamma Stimulation and Opioid Tolerance

说明(申请人提供)：关于阿片类药物耐受性的研究继续受到以下信念的启发，即阐明与这种情况有关的因果适应将有助于开发改善其疗效的药物疗法，从而提高麻醉药品的药用价值。对阿片类药物的耐受是保护性的。它与一系列被认为是适应性的神经化学变化有关。迄今已确定的对吗啡持续存在的适应通常分为两大类，一类是导致阿片受体介导的信号实际丧失的适应，另一类是通过掩盖阿片受体介导的信号导致这一活动明显丧失的适应。这些配方中的几个值得注意的缺陷促使我们的实验室假设了对慢性吗啡的互补适应策略。与流行的耐受模型不同，我们提出慢性吗啡会导致新的信号后遗症的出现，但不会消失。具体地说，我们证明了不需要改变阿片受体G蛋白偶联的阿片受体G蛋白偶联的适应性促进了阿片受体偶联GPY对腺酰环化酶(AC)的刺激。在目前的提案中，我们将在我们的配方中增加一个新的维度，部分原因是阿片受体GJG0信号的持续变化导致耐受，包括与Gs的增强偶联。到目前为止，这一直是有争议的，但基于我们最近对^-阿片受体(MOR)Gs关联的生化演示，这一点现在引起了人们的极大兴趣，这种关联在慢性吗啡后显著增强。其具体目标是：(1)确定参与耐受相关的增强MOR Gs偶联的GP异构体；(2)确定慢性吗啡降低GSA磷酸化从而增强其与MOR的联系的能力及其机制；(3)确定GSA磷酸化对其与AC相互作用的影响；(4)确定慢性吗啡对MORs Gs功能偶联的影响；以及(5)确定靶向改变信号平衡对先前确定的慢性吗啡神经化学适应的影响。这将确定容差适应不是硬连接的，而是取决于初始的稳定状态条件。总的来说，拟议的研究将有助于建立一个耐受性模型，该模型结合了信号分子相互关联的聚合变化的动态马赛克，试图重建功能平衡。

DESCRIPTION (provided by applicant): Research on opioid tolerance continues to be inspired by the conviction that elucidation of the adaptations causally associated with this condition will facilitate the development of pharmacotherapies for its amelioration and thus enhance the medicinal usefulness of narcotics. Opioid tolerance is protective. It has been associated with a wide spectrum of neurochemical changes believed to be adaptive. Adaptations to the persistent presence of morphine that have thus far been identified generally fall into two main categories, those that result in the actual loss of opioid receptor-mediated signaling and those that result in the apparent loss of this activity via its masking. Several noted deficiencies in these formulations prompted our laboratory to hypothesize complimentary strategies of adaptation to chronic morphine. In contrast to prevailing models of tolerance, we proposed that chronic morphine induces the emergence of new, but not lost, signaling sequelae. Specifically, we demonstrated adaptations that facilitated the emergence of opioid receptor- coupled GPY stimulation of adenylyl cyclase (AC) that did not require altered opioid receptor G protein coupling. In the current proposal, we will add a new dimension to our formulation that tolerance results, in part, from the altered consequences of continued opioid receptor GJG0 signaling to include enhanced coupling to Gs. This has heretofore been controversial but is now of compelling interest based on our recent biochemical demonstration of ^-opioid receptor (MOR) Gs association, which is markedly enhanced following chronic morphine. The specific objectives are to (1) Determine the Gp isoforms that participate in tolerance- associated enhanced MOR Gs coupling (2) Determine the ability of chronic morphine, and mechanisms thereof, to decrease phosphorylation of GSa, and thereby enhance its association with MOR, (3) Determine the influence of GSa phosphorylation on its interaction with AC, (4) Determine the influence of chronic morphine on MOR Gs functional coupling and (5) Determine the effect of targeted alteration of signaling equilibria on previously defined neurochemical adaptations to chronic morphine. This will establish that tolerance adaptations are not hard wired but depend on initial steady state conditions. Collectively, proposed studies will help establish a model of tolerance that incorporates a dynamic mosaic of convergent interrelated changes in signaling molecules in an attempt to reestablish functional equilibria.