磷酸化c-Jun表达对亚急性帕金森病MPTP模型小鼠黑质COX-2表达的影响

目的 研究磷酸化c-Jun(p-c-Jun)在1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)所致亚急性帕金森病(PD)小鼠模型中对环氧合酶-2(COX-2)的表达调控作用,以探讨PD黑质多巴胺(DA)能神经元变性失活的可能机制.方法 采用MPTP制备亚急性PD小鼠模型.通过行为学观察,免疫组织化学SP法,免疫荧光双标记法和免疫蛋白印记法,观察模型小鼠行为学变化,观察PD模型小鼠黑质区酪氨酸羟化酶(TH)、COX-2和p-c-Jun免疫组织化学变化以及中脑黑质TH、COX-2和p-c-Jun表达水平的变化;观察给予JNK通路特异性剂SP-600125对上述变化的影响.结果 与对照组小鼠相比,模型组小鼠出现典型PD症状.黑质区TH阳性神经元下降约65%(P＜0.001),中脑黑质TH表达水平显著降低约75%;黑质区COX-2阳性细胞显著增加,中脑黑质COX-2表达水平明显升高;p-c-Jun特异性表达于黑质区细胞核内,p-c-Jun表达水平显著升高.免疫荧光双标记染色可见,COX-2和p-c-Jun共同表达于TH阳性细胞.抑制剂组,经SP600125处理后,模型小鼠PD症状减轻,与对照组比较,在MPTP第5次注射后七天,TH阳性细胞数和TH表达水平仅下降约15%和20%,与模型组比较,黑质区COX-2阳性细胞明显减少,中脑黑质COX-2表达水平明显降低,p-c-Jun仅表达于黑质区细胞的胞浆内,中脑黑质p-c-Jun表达水平明显下降.结论 p-c-Jun表达对亚急性帕金森病MPTP模型中脑黑质COX-2表达中可能起重要调控作用;抑制p-c-Jun表达对帕金森病小鼠可能具有一定的神经保护作用.

Effect of phosphorylated c-Jun expression on COX-2 expression in the substantia nigra of MPTP mouse model of subacute Parkinson disease

Objective To investigate the effect of phophorylated c-Jun(p-c-Jun)expression on the expression of COX-2 in the substantia nigra(SN)of the MPTP mouse model of subacute Parkinson disease(PD)and explore the possible mechanism of the dopaminergic(DA)neuron death in PD.Methods C57BL/6N mice were treated with MPTP to establish subacute PD model.The changes of TH-,COX-2-and p-c-Jun-positive cells,and the expression levels of TH,COX-2 and p-c-Jun in the SN in the midbrain were observed with inmmunohistochemistry and Western blotting before and after administration of SP600125,a specific JNK inhibitor.Results Compared with the mice in control group,the PD mice exhibited typical symptoms of PD.The number of TH-positive neurons and expression level of TH in the model group were significantly reduced in the substantia nigra by about 65% and 75%(P<0.001)7 days after the fifth injection of MPTP.The number of COX-2-immunoreactive cells and the expression level of COX-2 were significantly increased.P-c-Jun was specifically expressed in the nuclei of neurons and p-c-Jun expression level was significantly increased in the SN 6 h after the third injection of MPTP.Double-labeling immunofluorescence assay showed coexpression of COX-2 and p-c-Jun in TH-positive neurons in the SN.In mice treated with JNK inhibitor,the number of TH-positive neurons and TH expression level in the SN was only decreased by 15% and 20% as compared with the control group(P<0.001)7 days after the fifth injection of MPTP,COX-2-positive cell number and COX-2 expression level were obviously reduced as compared with the model group(P<0.001),and p-c-Jun was expressed mainly in the cytoplasm of the neurons whose expression level in SN were significantly decreased 6 h after the third injection of MPTP.The PD mice treated with SP600125 showed slight behavioral symptoms.Conclusion P-c-Jun expression may play an important role in mediating COX-2 expression in the SN in the MPTP model of subacute PD,and inhibiting p-c-Jun activity may provide neuroprotection to the mouse model.