Effects of sevoflurane and desflurane on the nociceptive responses of substantia gelatinosa neurons in the rat spinal cord dorsal horn: An in vivo patch-clamp analysis
Effects of sevoflurane and desflurane on the nociceptive responses of substantia gelatinosa neurons in the rat spinal cord dorsal horn: An in vivo patch-clamp analysis
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DOI：
10.1177/1744806920903149
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发表时间：
2020-02-01
期刊：
影响因子：
3.3
通讯作者：
Nishikawa, Kiyonobu
中科院分区：
文献类型：
--
作者：
Inada, Yosuke;Funai, Yusuke;Nishikawa, Kiyonobu
### 背景
挥发性麻醉药可抑制脊髓背角由伤害性刺激诱发的活动，这在一定程度上有助于产生镇痛和制动作用。对胶状质神经元兴奋性和抑制性突触传递的调节可能导致背角活动受到抑制；然而，这一现象尚未得到充分研究。
### 方法
在乌拉坦麻醉的大鼠中，分别采用细胞外记录技术和在体膜片钳技术，记录背角神经元的细胞外活动（动作电位）以及胶状质神经元的兴奋性/抑制性突触后电流，以评估自发活动和伤害性刺激诱发的活动。通过吸入给予浓度范围为0.1至2个最低肺泡浓度的七氟醚或地氟醚。在吸入较低麻醉剂量（0.1 - 0.5个最低肺泡浓度）的挥发性麻醉药期间，进行热板和冷板试验以评估伤害性反应。
### 结果
在麻醉剂量（1和2个最低肺泡浓度）下，七氟醚和地氟醚均降低了夹捏刺激时背角动作电位的频率以及胶状质神经元中兴奋性突触后电流的活动，还降低了自发和微小兴奋性突触后电流的活动。在这些麻醉剂量下，自发和微小兴奋性突触后电流频率的抑制比幅度的抑制更为显著。然而，在亚麻醉剂量（0.1和0.2个最低肺泡浓度）下，地氟醚促进了动作电位和兴奋性突触后电流。在麻醉剂量（1和2个最低肺泡浓度）下，两种麻醉药均抑制了抑制性突触后电流。热板或冷板试验显示，地氟醚在亚麻醉剂量（0.1和0.2个最低肺泡浓度）下具有痛觉过敏效应，而七氟醚具有剂量依赖性的镇痛作用。
### 结论
麻醉剂量的七氟醚和地氟醚主要通过抑制胶状质神经元中的兴奋性突触后电流来抑制背角活动，这有助于它们发挥镇痛特性。兴奋性突触后电流的抑制可能存在突触前机制。地氟醚在亚麻醉剂量下可能具有痛觉过敏效应，而七氟醚则无此效应。
BackgroundVolatile anesthetics suppress noxiously evoked activity in the spinal dorsal horn, which could contribute in part to analgesia, immobility. Modulation of excitatory and inhibitory synaptic transmission in substantia gelatinosa neurons could lead to the suppression of dorsal horn activity; however, this phenomenon has not yet been investigated fully.MethodsIn urethane-anesthetized rats, extracellular activity of dorsal horn neurons (action potentials) and excitatory/inhibitory postsynaptic currents in substantia gelatinosa neurons were recorded using extracellular and in vivo patch-clamp techniques, respectively, to assess the spontaneous and the noxious-evoked activity. Sevoflurane or desflurane at concentrations ranging from 0.1 to 2 minimum alveolar concentration was administered by inhalation. Hot- and cold-plate tests were performed to assess nociceptive responses during the inhalation of volatile anesthetics at lower anesthetic doses (0.1-0.5 minimum alveolar concentration).ResultsAt anesthetic doses (1 and 2 minimum alveolar concentration), both sevoflurane and desflurane decreased the frequency of action potentials in the dorsal horn and the activities of excitatory postsynaptic currents in substantia gelatinosa neurons during pinch stimulation and decreased the activities of spontaneous and miniature excitatory postsynaptic currents. Inhibition of the frequencies was more prominent than that of amplitudes in spontaneous and miniature excitatory postsynaptic currents at these anesthetic doses. However, at subanesthetic doses (0.1 and 0.2 minimum alveolar concentration), desflurane facilitated action potentials and excitatory postsynaptic currents. Inhibitory postsynaptic currents were inhibited by both anesthetics at anesthetic doses (1 and 2 minimum alveolar concentration). Hot- or cold-plate tests showed hyperalgesic effects of desflurane at subanesthetic doses (0.1 and 0.2 minimum alveolar concentration) and a dose-dependent analgesic effect of sevoflurane.ConclusionsSevoflurane and desflurane at anesthetic doses suppressed dorsal horn activity mainly via inhibition of excitatory postsynaptic currents in substantia gelatinosa neurons, which would contribute to their analgesic properties. Presynaptic mechanisms were likely in excitatory postsynaptic currents inhibition. Desflurane but not sevoflurane may have a hyperalgesic effect at subanesthetic doses.