Interaction of opioid and local anesthetics on spinal dorsal horn neuron

本研究选用雄性SD大鼠。实验分为两组：1)电生理研究；2)行为学研究。1)氟烷麻醉下，腰椎椎板切除和鞘内插管。记录单个背角神经元的胞外活动。当分离对伤害性和非伤害性刺激都有反应的大动态范围神经元时，少数神经元同时对内脏刺激(结直肠扩张)有反应。鞘内注射吗啡可抑制这些神经元对伤害性刺激的反应。2)分别于硬膜外注射或鞘内持续注入吗啡、利多卡因后180min测定甩尾潜伏期和结直肠肿胀阈值。等效谱分析、效价比分析和分数分析表明，在躯体和内脏伤害性试验中，吗啡和利多卡因具有协同作用。

Male Sprague-Dawley rats were used in this study. The animals were divided into two experiments ; 1) electrophysiological study or 2) behavioral study.1) Under halothane anesthesia, lumbar laminectomy and intrathecal catheterization were peformed. The extracellular activity was recorded from a single dorsal horn neurons. When wide dynamic range neurons responsive to both noxious and non-noxious stimuli were isolated, a few neuron simultaneously responded to the visceral stimulus (colorectal distension). Intrathecal administration of morphine inhibited the response of those neurons to noxious stimuli. However, it has not yet determined the interaction of intrathecally coadminitered morphine and lidocaine due to small sample, to date.2) Tail flick latency and colorectal distension threshold were measured before and for 180 min after the epidural injection or continuous intrathecal infusion of morphine, lidocaine, or combination of those drugs. Isobolographic analysis, potency ratio analysis and fractional analysis revealed that morphine and lidocaine interact synergistically in both somatic and visceral nociception tests.