OPIOID AND ALPHA-ADRENERGIC AGONIST INTERACTIONS

拟定研究的目的是阐明机制 对于脊髓给药的阿片类药物和 α-肾上腺素能激动剂的抗伤害反应。 使用 阿片类药物在疼痛的临床治疗中的作用是复杂的， 不可避免的发展的耐受性和身体依赖这些 毒品 开发一种治疗方案， 阿片类药物与非阿片类药物联合使用以增强疗效 阿片类药物可能会更有效地管理疼痛， 产生不期望的阿片类药物副作用。 抗伤害感受 观察到的外周给药吗啡可能是一种表现， 吗啡和吗啡之间的协同作用 同时在脊柱和脊柱上部位。 脊柱上给药 吗啡激活下行疼痛抑制控制系统， 通过释放的单胺在脊髓水平介导。 有刺的 施用的吗啡直接作用于脊髓中的阿片受体 脊髓产生抗伤害感受。 脊柱/脊柱上的协同作用可能是 这是在脊柱水平上， 脊柱给药的阿片样物质和释放的去甲肾上腺素;即， 阿片类和非阿片类系统的激活。 由于两种受体类型 可能共定位于相同的脊髓神经元和两者的激动剂 受体激活类似的第二信使系统，这种相互作用可能 发生在受体之间，或G蛋白之间，或第二个 由受体激活的信使。 将进行实验以： (1)明确确定特定阿片类药物和α的亚型， 肾上腺素能受体参与抗伤害协同作用 使用受体选择性激动剂和拮抗剂的相互作用。 的ed 50 将获得小鼠甩尾试验的值， 将通过等效线评价激动剂之间的差异;（2）确定 两种受体类型之间可能发生的任何相互作用， 竞争性结合试验;（3）鉴定相互作用的G蛋白 与脊髓神经元膜上的这些受体结合， 毒素催化的ADP-核糖基化和[32 p]NAD，或与 [32 p]GTP叠氮基苯胺;（4）检查第二个之间的相互作用 由阿片样物质和α肾上腺素能激动剂激活的信使系统， 具体地，腺苷酸环化酶活性的抑制和 使用脊髓膜的细胞内钙浓度， 培养的背根神经节和克隆细胞表达阿片样物质， 和阿尔法受体。 脊髓/脊髓上吗啡协同作用的减少发生在 吗啡耐受小鼠被认为是 对吗啡的耐受性 因此，拟议的研究将 还检查了阿片类药物/肾上腺素能相互作用的变化， 在对动物或培养的神经元进行慢性阿片样物质处理后， 细胞 这些研究将提供深入了解发展机制 对吗啡的耐受和身体依赖

The aim of the proposed investigations is to elucidate the mechanism(s) for the synergistic interaction between spinally administered opioid and alpha-adrenergic agonists for the antinociceptive response. The use of opioids in the clinical management of pain is complicated by the unavoidable development of tolerance and physical dependence to these drugs. Development of a treatment regimen that would allow small doses of opioids in combination with non-opioid drugs to enhance the efficacy of opioids might allow more efficient pain management with less development of the undesirable opioid side effects. The antinociception observed for peripherally administered morphine may be a manifestation of the synergistic interaction that occurs between morphine administered concurrently at spinal and supraspinal sites. Supraspinally administered morphine activates a descending pain inhibitory control system which is mediated at the spinal level by released monoamines. Spinally administered morphine acts directly on opioid receptors in the spinal cord to produce antinociception. The spinal/supraspinal synergism may be a result of the synergistic interaction at the spinal level between the spinally administered opioid and the released norepinephrine; i.e., activation of opioid and non-opioid systems. Since both receptor types may be co-localized on the same spinal neurons and agonists of both receptors activate similar second messenger systems, this interaction may occur between the receptors, or between the G-proteins or second messengers activated by the receptors. Experiments will be performed to: (1) establish clearly the subtypes of the specific opioid and alpha adrenergic receptors involved in the antinociceptive synergistic interaction using receptor-selective agonists and antagonists. The ED50 values for the tail flick test in mice will be obtained and interactions between agonists will be evaluated isobolographically; (2) establish that any interaction which may occur between the two receptor types using competitive binding assays; (3) identify the G-proteins that interact with these receptors in spinal cord neuronal membranes using cholera toxin catalyzed ADP-ribosylation and [32p]NAD, or interaction with [32p]GTP azidoaniline; (4) examine the interaction between second messenger systems activated by opioid and alpha adrenergic agonists, specifically, inhibition of adenylyl cyclase activity and decreased intracellular calcium concentrations using spinal cord membranes, cultured dorsal root ganglia and clonal cells which express both opioid and alpha receptors. The decrease in spinal/supraspinal morphine synergism that occurs in morphine-tolerant mice has been proposed as a mechanism for development of tolerance to peripheral morphine. Thus, the proposed studies will also examine the changes in opioid/adrenergic interactions that may occur after chronic opioid treatment of either animals or cultured neuronal cells. These studies will provide insight into mechanisms of development of tolerance and physical dependence to morphine.