电针联合鞘内注射芬太尼对慢性炎性痛大鼠脊髓背角孤啡肽mRNA和脑源性神经营养因子mRNA表达的影响

Effects of electroacupuncture combined with intrathecal fentanyl on expression of orphanin FQ mRNA and brain-derived neurotrophic factor mRNA in spinal dorsal horn in rats with chronic inflammatory pain

目的 观察电针联合鞘内注射芬太尼对慢性炎性痛大鼠脊髓背角孤啡肽（OFQ）mRNA及脑源性神经营养因子（BDNF）mRNA表达的影响，探讨其镇痛机制。方法 鞘内置管成功的成年雌性SD大鼠30只，随机分为5组（n=6）：正常组（A组）、致炎组（B组，大鼠右踝关节腔内注射完全弗氏佐剂50μl）、电针组（C组，大鼠致炎后第4、7、10天电针阳陵泉和足三里，频率2 Hz／100 Hz，强度≤2 mA，30min／次）、芬太尼组（D组，大鼠致炎后第4天开始，连续7 d鞘内注射芬太尼10μl）和针药合用组（E组，针药使用方法同C组、D组）。热板法测定大鼠痛敏分数。于致炎后第11天取L4-6脊髓，采用RT-PCR法检测大鼠脊髓背角OFQ mRNA和BDNF mRNA表达，并采用电泳图像分析系统行半定量分析。结果 与A组相比，B组OFQ mRNA及BDNF mRNA表达升高（P〈0．05）;与B组相比，C组、D组、E组痛敏分数降低（P〈0．05），OFQ mRNA及BDNF mRNA表达降低（P〈0．05）;与C组相比，E组痛敏分数降低（P〈0．05），OFQ mRNA及BDNF mRNA表达降低（P〈0．05）。结论 慢性炎性痛大鼠针药合用的镇痛效果强于单独使用电针，其镇痛机制与抑制OFQ和BDNF在脊髓背角的表达有关。

Objective To investigate the effects of electroacupuncture （EA） combined with intrathecal （IT） fentanyl on the expression or orphanin FQ （OFQ） mRNA and braln-derived neurotrophic factor （BDNF） mRNA in the spinal dorsal horn in rats with chronic inflammatory pain （CIP） .Methods Thirty adult female SD rats weighing 200-240 g were randomly divided into 5 groups （ n = 6 each） ： A control; B CIP; C EA ＋ CIP; D IT fentanyl ＋ CIP and E EA ＋ IT fentanyl ＋ CIP. CIP was induced by injection of complete Freund＇s adjuvant （CFA） 50μl into right tibio-tarsal joint. In group D and E fentanyl 10μl was injected intrathecally via an IT catheter once a day for 7 consecutive days starting from the 4th day after CIP was induced. In group C and E electrical stimulation of Yanglingquan and Zusanli was performed for 30 min per day on the 4th, 7th and 10th day after CIP was induced. The paw-withdrawal latency to noxious thermal stimulation was measured using hot plate test and compared between the right and left hindpaw. The lumbar segment （L4-6） of spinal cord was removed on the llth day after induction of CIP for determination of OFQ mRNA and BDNF mRNA expression in the spinal dorsal horn using RT-PCR. Results The thermal hyperalgesia and increase in OFQ mRNA and BDNF mRNA expression in spinal dorsal horn induced by CIP were significantly attenuated by EA and/or IT fentanyl. EA combined with IT fentanyl provided best analgesia. Conclusion EA can enhance the analgesic effect of fentanyl in rats with chronic inflammatory pain. The changes in OFQ and BDNF in spinal dorsal horn are involved in the mechanism of analgesia produced by EA and fentanyl.