大鼠脊髓内吗啡肽2的表达与腰椎间盘突出症坐骨神经痛的相关性分析

Correlation between spinal endomorphin-2 expression and lumbar disc herniation sciatica in rats

目的观察腰椎间盘突出症坐骨神经痛(LDHS)大鼠痛行为变化及其与脊髓背角内吗啡肽2(EM2)表达变化的关联性。方法SD大鼠随机分为LDHS组、假处理组和对照组。LDHS组采用自体髓核移植法造模,假处理组采用相同的手术过程而未移植髓核,对照组未经任何处理。每组在造模前和造模后5、10、15、20、25 d先进行痛行为检测;然后在LDHS组痛行为的峰值状态下开展行为药理学实验,即经脊柱鞘内置管后注射不等剂量的μ型阿片受体拮抗剂——β-富纳曲胺(β-FNA)、EM2、内吗啡肽1(EM1)或吗啡,记录痛觉阈值的变化;最后利用高效液相色谱法和免疫荧光组织化学染色检测脊髓EM2的表达变化。结果与假处理组和对照组比较,LDHS组在造模后5 d痛觉阈值显著降低,15 d时痛觉阈值达到最低点(P<0.05);LDHS组鞘内给予β-FNA可使疼痛进一步加深,鞘内给予EM2、EM1或吗啡均能剂量依赖地产生镇痛作用,但EM2镇痛作用比EM1和吗啡强;与假处理组和对照组比较,LDHS大鼠脊髓背角EM2的免疫荧光染色强度和脊髓EM2的表达水平均显著减低(P<0.05),痛觉阈值与EM2表达量呈显著正相关(r=0.966,P<0.001)。结论LDHS状态下脊髓水平EM2的低表达导致了大鼠下肢疼痛状态的产生。

Objective To observe the pain behavior change in rat lumbar disc herniation sciatica(LDHS)and its relationship with the expression of endomorphin-2(EM2)in spinal dorsal horn.Methods The SD rats were randomly divided into the LDHS group,sham operation group and control group.The LDHS group adopted the autologous nucleus pulposus transplantation for constructing the model,the sham operation group adopted the same operation process without implantation of nucleus pulposus.The control group had no any treatment.The pain behavior in each group was detected before modeling and on 1,10,15,20,25 d after modeling.Subsequently,the pharmacological experiment was carried out in the peak value state of pain behavior in the LDHS group,namely,different doses of theμtype opioid receptor antagonistβ-FNA,EM2,EM1 or morphin was injected after spinal intrathecal indwelling tube.The pain sense threshold value change was recorded;finally,HPLC and immunofluorescence histochemical staining were used to detect the expression change of spinal EM2.Results Compared with the sham operation group and control group,the pain threshold on 5 d after modeling in the LDHS group was decreased significantly and reached the lowest point on 15 d(P<0.05).Intrathecal injection ofβ-FNA in the LDHS group could further deepen pain,and the intrathecal injection of EM2,EM1 or morphine all could generate the analgesic effect by dose dependence,but the analgesic effect of EM 2 was stronger than that of EM1;the immunofluorescence staining density and the expression level of spinal EM2 in the LDHS group were significantly decreased(P<0.05).The decrease of pain sense threshold value showed the significantly positive correlation with down-regulation of EM2 expression level(r=0.966,P<0.001).Conclusion In the state of LDHS,the low expression of spinal EM2 contributes to the generation of lower limb pain in rats.