不同浓度沙利度胺对大鼠慢性坐骨神经缩窄模型的镇痛效果及机制

目的:比较不同剂量沙利度胺对大鼠慢性坐骨神经缩窄(chronic sciatic nerve constriction,CCI)的镇痛效果及可能机制。方法:将50只大鼠随机分为S组、C组、L组、M组及H组,S组作为假手术组,其余四组建立CCI模型,术后分别用20 mg/kg、50mg/kg、100 mg/kg沙利度胺处理L组、M组、H组。于术后第1、2、3、4周测量和比较各组大鼠机械性痛阈与热痛阈,采用蛋白质印迹法(Western blot)及实时荧光定量PCR(Q-PCR)检测各组大鼠肿瘤坏死因子受体(TNFR)的mRNA和蛋白表达,并分析沙利度胺浓度与TNFR mRNA相对表达的相关性。结果:S组术前术后的机械性痛阈与热痛阈均无明显改变(P0.05),其余四组术后痛阈均较术前明显下降(P0.05);C组术后第4周时机械性痛阈明显升高(P0.05),而术后其他时间点的机械性痛阈与热痛阈无明显差异(P0.05);L组、M组、H组术后机械性痛阈、热痛阈随时间的延长呈上升趋势,差异有统计学意义(P0.05)。术后,C组机械性痛阈与热痛阈对比S组明显降低(P=0.000),亦显著低于L组(P=0.000);而不同剂量组机械性痛阈、热痛阈相比,H组高于M组(P=0.000),M组高于L组(P=0.000)。相对于C组,L组、M组、H组术后第4周TNFR1 mRNA及蛋白相对含量显著下降(P0.05),其中H组下降最为明显,M组次之。Pearson相关性分析结果显示:沙利度胺浓度的增加与TNFR1表达水平的升高呈明显负相关关系(r=-0.497,P=0.036)。结论:沙利度胺可能通过影响TNFR表达水平对大鼠慢性坐骨神经缩窄发挥镇痛效应,其镇痛效应随剂量增加而加强,有望作为神经病理性疼痛的辅助镇痛药物之一。

Association between TNF Receptor Levels Affected by Thalidomide and Analgesic Effect on a Rat Model of CCI

ABSTRACT Objective: To compare the analgesic effects and possible mechanisms of different doses of thalidomide on chronic sciatic nerve constriction (CCI) in rats. Methods: Fifty rats were randomly divided into group S, group C, group L, group M, group H and group S were considered as the sham operation group. CCI model were established in the other four groups. After operation, group L, group M and group H were treated by 20 mg/kg, 50 mg/kg and 100 mg/kg thalidomide, respectively. The mechanical pain threshold and thermal pain threshold of each group were measured and compared at 1, 2, 3 and 4 weeks after operation. Western blot and real-time fluorescent quantitative PCR (Q-PCR) were used to analyze the mRNA and protein expressions of tumor necrosis factor receptor (TNFR). The correlation of thalidomide concentration with the relative expression of TNFR mRNA was analyzed. Results: There was no significant difference in the mechanical pain threshold and thermal pain threshold in group S before and after operation (P>0.05), and the pain threshold in the other four groups was significantly lower than that before operation (P<0.05). The mechanical pain threshold was significantly increased in group C at the fourth week (P<0.05), but there was no significant difference in mechanical pain threshold and thermal pain threshold at other time points after operation (P>0.05). The mechanical pain threshold and thermal pain threshold of group L, group M and group H increased over time, and the differences were statistically significant (P<0.05). After operation, the mechanical pain threshold and thermal pain threshold in group C were significantly lower than those in group S (P=0.000), and also were significantly lower than those in group L (P=0.000). However, in the comparison of mechanical pain threshold and thermal pain threshold among different groups, group H was higher than group M (P=0.000), and group M was higher than group L (P=0.000). Compared with group C, the relative content of TNFR1 mRNA and protein in group L, group M and group H decreased significantly (P<0.05), especially in H group and M group. Pearson correlation analysis showed that the increase of thalidomide concentration was negatively correlated with TNFR1 expression (r=-0.497, P=0.036). Conclusion: Thalidomide may exert an analgesic effect on the chronic constriction of the sciatic nerve in rats by affecting the expression of TNFR, and its analgesic effect may be enhanced with the increase of the dosage. Thalidomide is hoped to be one of the auxiliary analgesic drugs for neuropathic pain.