甲醛炎性痛对大鼠脊髓HO-1表达的影响

目的:观察足底注射甲醛引起的外周组织炎性疼痛是否可诱导大鼠脊髓血红素氧合酶-1(HO-1)表达发生改变以及变化的时程特征。方法:健康雄性SD大鼠随机分为7组(n=6):对照组(control组)、甲醛6 h组(F6 h组)、甲醛12 h(F12 h组)、甲醛1 d组(F1 d组)、甲醛2 d组(F2 d组)、甲醛3 d组(F3 d组)和甲醛7 d组(F7 d组)。采用足底注射甲醛溶液复制炎性痛模型,采用免疫组织化学方法检测左、右两侧脊髓后角以及中央管周围灰质HO-1蛋白的表达。结果:Control组大鼠HO-1免疫反应阳性细胞在脊髓后角及中央管周围灰质仅有少量分布,且这些细胞染色较浅。足底注射甲醛后6 h,L5节段双侧脊髓后角和中央管周围灰质HO-1免疫反应阳性细胞数目即有所增多,足底注射甲醛后12 h时,双侧脊髓后角和中央管周围灰质HO-1免疫反应阳性细胞数目进一步增多,阳性细胞染色明显加深,1 d时阳性细胞数目和染色深度均达到高峰,7 d时仍高于control组水平。各时间点双侧脊髓后角比较,阳性细胞数目和阳性细胞染色深度均无明显差异。结论:大鼠足底注射甲醛引起的炎性痛可诱导双侧脊髓后角和中央管周围灰质HO-1表达增多,以注射甲醛后1 d时增多最为明显。

Effect of formalin inflammatory pain on expression of HO-1 in spinal cord of rats

Objective: To investigate whether formalin inflammatory pain can induce the change in heme oxygenase-1(HO-1)expression in the spinal cord of rats or not and the time course character.Methods: 42 SD rats were divided into 7 groups(n=6): control formalin 6 h,formalin 12 h,formalin 1 d,formalin 2 d,formalin 3 d and formalin 7 d groups.Rats were subcutaneously injected with 0.2 ml 0.5% formalin into the ventral surface of right hind paw to induce periphery inflammatory pain.The immunohistochemistry was used to observe the expression of HO-1 protein in laminasⅠ-Ⅱof the spinal cord dorsal horn and the area around canalis centralis of the L5 spinal segment of rats.Results: There are rare HO-1 immunoreactive cells in the laminasⅠ-Ⅱof the dorsal horn and the area around canalis centralis of the L5 spinal segment of rats of control group and HO-1immunoreactive cells were light in staining degree.Comparing with control group,the numbers of HO-1 immunoreactive cells in theⅠ-Ⅱlaminas of dorsal horn and area around canalis centralis were increased in the rats at 6 h after formalin injection.The number and staining degree of HO-1 immunoreactive cells were further increased at 12 h and peaked at 1 d after formalin injection.They didn’t return to normal level at the 7th day.There were no difference in right and left dorsal horn in the number and staining degree of HO-1 immunoreactive cells at the same time after formalin injection.Conclusion: Formalin inflammatory pain induced increased expression of HO-1 in the spinal cord dorsal horn and the area around canalis centralis of rats.At 1 d after injection of formalin,the increased expression of HO-1 was the most obviously.