OPIOID AND ALPHA-ADRENERGIC AGONIST INTERACTIONS

拟议调查的目的是阐明这一机制(S) 脊椎给药阿片类药物与阿片类药物的协同作用 抗伤害性反应的α-肾上腺素能激动剂。对.的使用 阿片类药物在疼痛临床治疗中的复杂性 不可避免地会产生对这些疾病的耐受性和身体依赖 毒品。开发一种允许小剂量的治疗方案 阿片类药物与非阿片类药物联合应用以提高疗效 阿片类药物的使用可能会以更少的费用更有效地控制疼痛 不良阿片类药物副作用的发展。抗伤害性感觉 外周注射吗啡可能是一种表现 在注射吗啡之间发生的协同作用 同时出现在脊柱和脊柱上的部位。冈上给药 吗啡激活下行疼痛抑制控制系统 由释放的单胺在脊髓水平上进行调节。脊椎状 注射吗啡直接作用于脊髓中的阿片受体 产生抗伤害性感觉的绳索。脊柱/脊柱上的协同作用可能是 在脊柱水平上的协同作用的结果是 脊椎注射的阿片类药物和释放的去甲肾上腺素；即， 阿片和非阿片系统的激活。由于两种受体类型 可能共同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，或者发生在G蛋白之间或第二 由受体激活的信使。将进行以下实验： (1)明确特定阿片类药物和阿尔法类药物的亚型 肾上腺素能受体参与抗伤害性协同作用 使用受体选择性激动剂和拮抗剂的相互作用。ED50 将获得小鼠甩尾试验的值，并进行相互作用 激动剂之间将进行等位同构学评估；(2)确定 这两种受体类型之间可能发生的任何相互作用 竞争结合分析；(3)鉴定相互作用的G蛋白 用这些受体在脊髓神经元膜上使用霍乱 毒素催化的ADP-核糖基化和[32P]NAD，或与 [32P]GTP叠氮苯胺；(4)考察二次反应的相互作用 由阿片和α肾上腺素能激动剂激活的信使系统， 具体地说，抑制腺酰环化酶的活性并降低 使用脊髓膜的细胞内钙浓度， 培养的背根神经节和表达阿片类物质的克隆性细胞 和阿尔法受体。 脊髓/脊髓上吗啡协同作用的降低发生在 吗啡耐受小鼠被认为是发育的一种机制 对外周吗啡的耐受性。因此，拟议的研究将 还要检查可能发生的阿片类药物/肾上腺素能相互作用的变化 在动物或培养神经元的慢性阿片类药物治疗后 细胞。这些研究将提供对发展机制的洞察。 对吗啡的耐受性和身体依赖性。

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.