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目的:探讨催产素在脊髓后角胶状质细胞层的镇痛机制。方法:本研究使用成年雄性SD大鼠,运用椎板切除术取出脊髓腰骶膨大节段(L1~S3),并置于1~3℃的Krebs液中。用切片机制作脊髓横切片,该切片被置于记录槽中并给予Krebs液灌流。运用盲法全细胞膜片钳技术记录催产素对脊髓横切片中胶状质神经元电生理活动的影响。结果:在钳制电压为-70 m V时,灌流催产素(0.5μM/L)3分钟可诱发内向电流;并且该内向电流不能被TTX阻断。但催产素对自发性兴奋性突触后电流无影响。另外催产素增加了γ-氨基丁酸与甘氨酸介导的自发性抑制性突触后电流的频率和振幅,而该增加可被TTX抑制。催产素受体激动剂TGOT能够模拟催产素的效果,诱发胶状质细胞出现内向电流;催产素受体抑制剂d VOT能抑制催产素所引起的内向电流。结论:在脊髓后角胶状质细胞层,催产素通过激活催产素受体引起胶状质细胞的膜去极化,从而引起抑制性神经递质的释放增加,达到抑制疼痛信息传导的效果。
Objective: To investigate the analgesic mechanism of oxytocin in the gliacyte layer of the spinal cord. Methods: Adult male Sprague-Dawley rats were used in this study. The lumbosacral dilatation segments (L1 ~ S3) were removed by laminectomy and placed in Krebs solution at 1 ~ 3 ℃. A transection of the spinal cord was made using a microtome, which was placed in a recording slot and perfused with Krebs fluid. The effect of oxytocin on electrophysiological activity of neuroglia in spinal cord transverse section was recorded by blinded whole-cell patch-clamp technique. Results: At a clamping voltage of -70 mV, inward current was induced by perfusion of oxytocin (0.5 μM / L) for 3 minutes; and this inward current could not be blocked by TTX. But oxytocin had no effect on spontaneous excitatory postsynaptic currents. In addition, oxytocin increases the frequency and amplitude of gamma-aminobutyric acid and glycine-mediated spontaneous inhibitory postsynaptic currents, and this increase can be suppressed by TTX. The oxytocin receptor agonist TGOT mimics the effects of oxytocin and induces an inward current in the gliocytes. The oxytocin receptor inhibitor d VOT inhibits oxytocin-induced inward currents. CONCLUSION: Oxytocin causes membrane depolarization of the gliacytes of the gliocytes via activation of the oxytocin receptor in the gliacyte compartment of the spinal cord, resulting in an increase in the release of inhibitory neurotransmitters and an inhibitory effect on the transmission of pain information.