鞘内给予右美托咪定的镇痛作用及其神经毒性的分子机制：一项体内和体外实验研究。

Molecular mechanisms underlying the analgesic property of intrathecal dexmedetomidine and its neurotoxicity evaluation: an in vivo and in vitro experimental study.

机构信息

The First Clinical College, China Medical University, Shenyang, Liaoning, People's Republic of China.

出版信息

PLoS One. 2013;8(2):e55556. doi: 10.1371/journal.pone.0055556. Epub 2013 Feb 7.

BACKGROUND

Dexmedetomidine (DEX) has been used under perioperative settings as an adjuvant to enhance the analgesic property of local anesthetics by some anesthesiologists. However, the analgesic mechanisms and neurotoxicity of DEX were poorly understood. This study examined the effect of DEX alone on inflammatory pain, and it also examined the underlying molecular mechanisms of DEX in the spinal cord. Furthermore, in vivo and in vitro experiments were performed to investigate the neurotoxicity of DEX on the spinal cord and cortical neurons.

METHODS

This study used adult, male Kunming mice. In the acute inflammatory model, the left hind-paws of mice were intradermally injected with pH 5.0 PBS while chronic constrictive injury (CCI) of the sciatic nerve was used to duplicate the neuropathic pain condition. Thermal paw withdrawal latency and mechanical paw withdrawal threshold were tested with a radiant heat test and the Von Frey method, respectively. Locomotor activity and motor coordination were evaluated using the inverted mesh test. Western blotting examined spinal ERK1/2, p-ERK1/2, caspase-3 and β-actin expressions, while spinal c-Fos protein expression was realized with immunohistochemical staining. Hematoxylin eosin (HE) staining was used to examine the pathological impacts of intrathecal DEX on the spinal cord. DAPI (4',6-diamidino-2-phenylindole) staining was used to observe cell death under an immunofluorescence microscope.

RESULTS

Intra-plantar pH 5.0 PBS-induced acute pain required spinal ERK1/2 activation. Inhibition of spinal ERK1/2 signaling by intrathecal injection of DEX displayed a robust analgesia, via a α2-receptor dependent manner. The analgesic properties of DEX were validated in CCI mice. In vivo studies showed that intrathecal DEX has no significant pathological impacts on the spinal cord, and in vitro experiments indicated that DEX has potential protective effects of lidocaine-induced neural cell death.

CONCLUSION

Intrathecal injection of DEX alone or as an adjuvant might be potential for pain relief.

背景

一些麻醉师在围手术期使用右美托咪定（DEX）作为辅助药物，以增强局部麻醉剂的镇痛作用。然而，DEX 的镇痛机制和神经毒性仍知之甚少。本研究检查了 DEX 单独对炎性疼痛的影响，还研究了 DEX 在脊髓中的潜在分子机制。此外，进行了体内和体外实验以研究 DEX 对脊髓和皮质神经元的神经毒性。

方法

本研究使用成年雄性昆明小鼠。在急性炎症模型中，将 pH 5.0 PBS 皮内注射到小鼠的左后爪中，同时使用坐骨神经慢性缩窄性损伤（CCI）来模拟神经病理性疼痛状态。使用辐射热测试和 Von Frey 方法分别测试热足潜伏期和机械足撤回阈值。使用倒置网格测试评估运动活动和运动协调性。Western blot 检测脊髓 ERK1/2、p-ERK1/2、caspase-3 和 β-actin 的表达，而脊髓 c-Fos 蛋白表达则通过免疫组织化学染色来实现。苏木精-伊红（HE）染色用于检查鞘内 DEX 对脊髓的病理影响。DAPI（4'，6-二脒基-2-苯基吲哚）染色用于在免疫荧光显微镜下观察细胞死亡。

结果

足底 pH 5.0 PBS 诱导的急性疼痛需要脊髓 ERK1/2 激活。鞘内注射 DEX 抑制脊髓 ERK1/2 信号传导通过 α2-受体依赖性方式显示出强大的镇痛作用。DEX 在 CCI 小鼠中的镇痛特性得到了验证。体内研究表明鞘内 DEX 对脊髓没有明显的病理影响，体外实验表明 DEX 具有潜在的保护作用，可减轻利多卡因诱导的神经细胞死亡。