【作者】 于玲；

【导师】 薛富善；

【作者基本信息】 中国协和医科大学 ， 麻醉学， 2006， 博士

【摘要】 一氧化氮与吗啡镇痛作用及其镇痛耐受关系的实验研究 吗啡是目前最常用于严重疼痛和慢性疼痛治疗的阿片类药物，其主要缺点是容易出现镇痛耐受，从而降低长期应用的镇痛效果。近年来，针对吗啡镇痛耐受已经开展了许多研究，通常认为其发生机制非常复杂，涉及许多生物因子和神经传导通路，并且其中的许多因素和环节尚未被完全阐明。一氧化氮（NO）是近年来倍受生物医学界关注的一种气体分子，作为一种重要的化学递质和细胞内信号分子，NO在机体内的许多生物调节机制中发挥着关键性作用。目前已有一些研究试图阐释NO在伤害性感受中的作用以及NO与阿片受体的相互作用，尤其是NO对吗啡镇痛及其镇痛耐受的影响，但是由于各研究所采用的实验动物模型、观察方法、给药途径和用药方法等方面的差别，因此未能取得一致的结果。由鉴于此，本研究采用福尔马林炎性疼痛和热甩尾测痛两种大鼠模型观察了单次和长期全身应用非特异性NOS抑制剂—L-NAME对吗啡镇痛作用及其镇痛耐受的影响；研究中检测了脊髓和中脑的c-fos基因表达、细胞外谷氨酸含量以及nNOSmRNA、NR1A（NMDA receptor subunit-1A）mRNA和NR2A（NMDA receptor subunit-2A）mRNA表达的变化，以探讨NO与吗啡镇痛及其镇痛耐受机制之间的关系。本研究的主要目的是进一步阐释NO在吗啡镇痛及其镇痛耐受中的作用，以为临床上解决吗啡镇痛耐受这一难题提供有益的启示。 第一部分 单次应用L-NAME对吗啡镇痛作用的影响 选择健康成年Sprague-Dawley（SD）大鼠60只，将其随机分成6组：1组（n=12）为对照组：腹腔注射生理盐水1ml，30min后再次腹腔注射生理盐水1ml；2组（n=6）：腹腔注射生理盐水1ml，30min后腹腔注射L-NAME 10mg／kg；3组（n=12）：腹腔注射生理盐水1ml，30min后腹腔注射L-NAME 20mg／kg：4组（n=12）：腹腔注射生理盐水1ml，30min后腹腔注射吗啡10mg／kg；5组（n=6）：腹腔注射L-NAME 10mg／kg，30min后腹腔注射吗啡10mg／kg。6组（n=12）：腹腔注射L-NAME 20mg／kg，30min后腹腔注射吗啡10mg／kg。在各组末次给药30min后，于大鼠左后掌皮下注射5％福尔马林0.1ml，随后50min内记录其舔咬注射足时间。除2组和5组之外，其他组动物分为两个亚组，第一亚组动物记录完毕后取L₅脊髓节段和中脑标本做c-fos免疫组织化学检查。第更多还原

【Abstract】 Morphine is an opioid most frequently used for management of severe and chronic pain. The main disadvantage of morphine is the development of tolerance to analgesia which decreases its long-term effect of pain relief. A number of studies on tolerance to morphine analgesia have been done for the past few years. It is generally belived that the mechanisms underlying tolerance to morphine analgesia are highly complicated and involve many biological molecules and neuronal pathways, some of which still remain unclear. Nitric oxide (NO), a gaseous molecule, has increasingly become the interests of the biomedical researches. As an important chemical mediator and intracellular signaling molecule, NO plays a key modulatory role in numerous biological mechanisms. There have been several relevant studies attempting to clarify the interaction of NO and opioid receptors and the roles of NO in the nociceptive processes and, particularly in the actions of NO on morphine analgesia and tolerance, however, the no consistent results are achieved due to the differences in the experimental animal models, study methods and drug regimens. Accordingly, we carried out the present experiments, using both the formalin-induced inflammation and the thermal tail-flick rat models, to explore the effects of a single or chronic systemic administration of nitric oxide synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME) on morphine analgesia and tolerance by measuring the expressions of c-fos gene, nNOSmRNA, NRlAmRNA, NR2AmRNA, and the extracellular concentrations of glutamate in spinal cord and midbrain, therey indentifing the relationship between NO and the mechanisms related to morphine analgesia and tolerance. The main purpose of our study is to further evaluate actions of NO on morphine analgesia and tolerance so as to provide a favorable inspiration for clinically dealing with tolerance to morphine analgesia.更多还原