腹腔注射利多卡因对切口痛模型大鼠自发痛行为及脊髓背角大麻素受体表达的影响

目的:探讨腹腔注射利多卡因对趾部切口疼痛模型大鼠自发痛行为和脊髓背角大麻素受体表达的影响。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5mg/kg组(C组)、利多卡因10mg/kg组(D组)、利多卡因20mg/kg(E组),于术前30min腹腔术前注射,每组6只。除A组外,其他4组按Brennan法制作趾部切口痛模型。术后6h观察动物疼痛行为的改变,以累计疼痛评分评定疼痛行为。术后7h取同侧脊髓,用免疫组化方法检测,脊髓背角大麻素(cannabinoid)受体表达水平的变化。结果:与A组相比,术后B组、C组、D组和E组大鼠的累积疼痛评分明显增加(P<0.01),脊髓背角大麻素受体(cannabinoid receptorCBR)表达减少(P<0.01)。与B组相比,D组和E组大鼠的累积疼痛评分降低(P<0.05),脊髓背角CBR表达增加(P<0.05),D组和E组无明显差别。C组和B组相比,累积疼痛评分无明显差别,但脊髓背角CBR表达增加(P<0.05)。结论:在大鼠切口疼痛模型中,利多卡因10mg/kg腹腔内注射利多卡因对大鼠疼痛行为有减轻的作用,其机制可能与脊髓背角CBR表达水平上调有关;增加利多卡因的浓度并没有更强的疼痛抑制作用。

Effects of peritoneal injection of Lidocaine on spontaneous pain behavior and expression of CBR in spinal dorsal horn by plantar incision in rats

Objective:To investigate the effect of peritoneal injection of Lidocaine on spontaneous pain behavior and expression of CBR in spinal dorsal horn by plantar incision in rats.Method:30 adult male SD rats(weight 200.0~250.0g) were randomly divided into five groups of 6 animals each:Group A(normal control group);group B(operation group):only a plantar incision was made;group C:Lidocaine 5.0mg/kg was given intraperitoneally 30min before the incision;group D:Lidocaine 10mg/kg was given intraperitoneally 30 min before incision;group E:Lidocaine 20mg/kg was given intraperitoneally 30min before the incision.An incision of 1cm long was made in the planter region under pentobarbital anesthesia according to the methods of Brennan.Pain behaviors was assessed using cumulative pain score 6h after incision.7h later rats were deeply anesthetized and the spinal cord was immediately removed and sliced and examined for CBR expression using immunohistochemistry.Result:Compared with group A,the cumulative pain score were increased and the expression of CBR were decreased significantly after plantar incision in group B,C,D and E(P<0.01).Compared with group B,the cumulative pain score decreased in group D and E(P<0.05),the expression of CBR increased in group D and E.There was no difference between group B and C as to the cumulative pain score,but the expression of CBR in group C was increased as compared with group B(P<0.05).Conclusion:In the model of rat plantar incision,Lidocaine 10mg/kg intraperitoneal injection can alleviate the pain behavior and the increased concentration of Lidocaine will not have much better effect,the pain alleviation effect of intraperitoneal injection of Lidocaine is related to its suppression of the expression of CBR.