腹腔注射利多卡因对切口痛大鼠脊髓背角NMDA受体-1表达的影响

目的:探讨腹腔注射利多卡因对切口痛模型大鼠痛觉行为和脊髓背角N-甲基-D-天冬氨酸(NMDA)受体-1(NR1)表达的影响。方法:雄性SD大鼠30只,随机分为5组:正常对照组(A组)、手术切口组(B组)、利多卡因5 mg/kg组(C组)、利多卡因10 mg/kg组(D组)及利多卡因20 mg/kg(E组)。除A组外,其他4组按Brennan法制作趾部切口痛模型。C、D、E三组于切口痛模型制备成功后腹腔注射相应剂量的利多卡因。注射后5 min开始观察5组大鼠痛觉行为的改变,以累计疼痛评分评定痛觉行为。观察1 h后取同侧脊髓,用免疫组化方法观察NR1表达的变化。结果:与A组相比,其余各组大鼠术后累积疼痛评分增加,脊髓背角NR1表达增强,差异均有统计学意义(P<0.01)。与B组相比,D组和E组大鼠的累积疼痛评分减少,脊髓背角NR1表达降低,差异均有统计学意义(P<0.05)。结论:腹腔注射利多卡因对切口痛大鼠具有较好的镇痛效果,并抑制其脊髓背角NR1的表达,提示其镇痛机制可能是通过抑制NR1的表达而实现的。

Effect of intraperitoneal injection of Lidocaine on expression of NMDAR1 in spinal dorsal horn of a rat model of incisional pain

Objective To investigate the effect of intraperitoneal injection of Lidocaine on pain behavior and expression of N-Methyl-D-aspartate（NMDA） receptor-1（NR1） in spinal dorsal horn of a rat model of incisional pain.Method Total 30 adult male SD rats（weight 200.0~250.0 g） were randomly divided into five groups,6 rats in each group：group A（normal control group）;group B（operation group）：only a plantar incision was made;group C：Lidocaine 5.0 mg/kg was given intraperitoneally after preparation of a successful model of incisional pain;group D：Lidocaine 10 mg/kg was given intraperitoneally after preparation of a successful model of incisional pain;group E：Lidocaine 20 mg/kg was given intraperitoneally after preparation of a successful model of incisional pain.Except group A,an incision of 1 cm long was made in the planter region of the rats in other 4 groups under pentobarbital anesthesia according to the methods of Brennan.Pain behaviors was assessed using cumulative pain score 5 min after intraperitoneal injection of Lidocaine.One hour later,rats were deeply anesthetized and the spinal cord was immediately removed and sliced and examined for NR1 expression using immunohistochemistry.Results Compared with group A,the cumulative pain score and the expression of NR1 in spinal dorsal horn were increased significantly after plantar incision in group B,C,D and E（P0.01）.Compared with group B,the cumulative pain scores were decreased significantly in group D and E（P0.05）,and the expression of NR1 in spinal dorsal horn were also significantly decreased in group D and E（P0.05）.Conclusion In the rat model of incisional pain,Lidocaine 10 mg/kg intraperitoneal injection can alleviate pain behavior and the increased concentration of Lidocaine will not have much better effect,and the results also suggest that the pain alleviation effect of intraperitoneal injection of Lidocaine is related to its suppression of the expression of NR1.