Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, China.
Neurochem Int. 2011 Apr;58(5):564-73. doi: 10.1016/j.neuint.2011.01.016. Epub 2011 Jan 25.
ATP facilitates initiation and transmission of the neuropathic pain at the dorsal root ganglion (DRG) level via the P2X receptors, especially the subtype P2X(3). Lappaconitine (LA) is an active principle isolated from Chinese herbal medicine and possesses analgesic effect. The aim of this study was to investigate the effect of LA on chronic constriction injury (CCI)-induced neuropathic pain mediated by P2X(3) receptor in the DRG neurons. In the presence of CCI and/or LA, the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured and P2X(3) receptor expression in the DRG neurons was evaluated by immunohistochemistry and Western blotting. Following intrathecal administration of P2X(3) receptor oligonucleotide, the effect of LA on pain thresholds was assessed. Furthermore, the effect of LA on the P2X(3) receptor agonists ATP- and α,β-meATP-induced inward currents (I(ATP) and I(α,β-meATP)) in the acutely dissociated rat DRG neurons was investigated by whole cell patch-clamp. The results included: (1) There showed reduction of pain thresholds, enhancement of I(ATP) and I(α,β-meATP) and up-regulation of P2X(3) receptor expression in rat DRG neurons when neuropathic pain occurred. (2) In the presence of LA, the decreased pain thresholds, the up-regulated P2X(3) receptor expression and the enhanced I(ATP) and I(α,β-meATP) were reversible in the CCI rats. (3) The down-regulated P2X(3) receptor expression with pretreatment of P2X(3) receptor antisense oligonucleotide significantly attenuated the analgesic effect of LA. These results indicate that the analgesic effect of LA involves decrease of expression and sensitization of the P2X(3) receptors of the rat DRG neurons following CCI.
三磷酸腺苷（ATP）通过 P2X 受体（尤其是 P2X(3)亚型）促进背根神经节（DRG）水平的神经性疼痛的起始和传递，而高乌甲素（LA）是一种从中药中分离出来的活性成分，具有镇痛作用。本研究旨在探讨 LA 对 P2X(3)受体介导的 DRG 神经元慢性缩窄性损伤（CCI）诱导的神经性疼痛的影响。在存在 CCI 和/或 LA 的情况下，通过机械性撤足阈值（MWT）和热撤足潜伏期（TWL）来测量，并用免疫组织化学和 Western blot 来评估 P2X(3)受体在 DRG 神经元中的表达。鞘内给予 P2X(3)受体寡核苷酸后，评估 LA 对痛阈的影响。此外，还通过全细胞膜片钳技术研究了 LA 对急性分离的大鼠 DRG 神经元中 P2X(3)受体激动剂 ATP 和 α,β-meATP 诱导的内向电流（I(ATP)和 I(α,β-meATP)）的影响。结果包括：（1）当发生神经性疼痛时，大鼠 DRG 神经元的痛阈降低，I(ATP)和 I(α,β-meATP)增强，P2X(3)受体表达上调。（2）在 LA 存在的情况下，CCI 大鼠的痛阈降低、P2X(3)受体表达上调以及 I(ATP)和 I(α,β-meATP)增强均为可逆的。（3）用 P2X(3)受体反义寡核苷酸预处理可显著下调 P2X(3)受体表达，从而减弱 LA 的镇痛作用。这些结果表明，LA 的镇痛作用涉及 CCI 后大鼠 DRG 神经元中 P2X(3)受体表达和敏化的下调。
