JNK通路在亚急性帕金森病模型小鼠黑质细胞炎症与凋亡过程中的调控作用

JNK signaling pathway regulates the process of neuroinflammation and apoptosis of nigral cells in the MPTP mouse model of subacute Parkinson′s disease

目的研究c-Jun N-terminal protein kinase(JNK)在1-甲基-4-苯基-1,2,3,6-四氢吡啶(1-Methyl-4-phenyl-1,2,3,6-tetrahy-dropyridine,MPTP)所致亚急性帕金森病(Parkinson's disease,PD)小鼠模型中对黑质环氧合酶-2(cyclooxygenase-2,Cox-2)、半胱氨酸天冬氨酸蛋白酶-3(caspase-3)的表达调控作用,以探讨PD模型黑质多巴胺(dopamine,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、SP法免疫组化和免疫蛋白印记法,观察模型小鼠黑质区酪氨酸羟化酶(tyrosine hydroxylase,TH)、Cox-2、caspase-3,磷酸化c-Jun(Ser63,p-c-Jun)免疫阳性细胞数量和中脑黑质区TH、Cox-2、caspase-3和p-c-Jun表达水平的变化;观察给予JNK通路特异性抑制剂SP600125后对上述变化的影响。结果与对照组小鼠相比,模型组小鼠出现PD典型的行为学表现,黑质区TH阳性神经元和中脑黑质TH含量分别下降约65%和75%,黑质区Cox-2与caspase-3阳性细胞数和中脑黑质Cox-2与caspase-3含量显著增加,黑质区p-c-Jun表达于细胞核内且中脑黑质p-c-Jun含量大幅升高;经JNK抑制剂SP600125处理的PD小鼠行为表现较轻,TH阳性神经元数量和TH表达水平仅较对照组分别下降约15%和25%,与模型组比较,Cox-2与caspase-3阳性细胞显著减少(P<0.001),p-c-Jun主要表达于细胞质内,中脑黑质Cox-2、caspase-3、p-c-Jun含量明显下降。结论JNK通路在MPTP诱导的黑质区细胞炎症与凋亡过程中可能起重要调控作用;JNK抑制剂对PD小鼠可能具有神经保护作用。

Purpose To investigate the effect of c-Jun N-terminal protein kinase （JNK） on the regulation of Cox-2 and caspase-3 in the substantia nigra （SN） of subacute Parkinson＇s disease （PD） induced by MPTP and explore the possible mechanism of the dopaminergic （DA） neuron death in PD. Methods C57BL/6N mice were administrated with MPTP to produce subacute PD model. The numbers of TH, Cox-2, caspase-3 and p-c-Jun positive cells, and the expression level of TH, Cox-2, caspase-3 and p-c-Jun in SN in the midbrain were observed with inmmunohistochemistry and Western blot. The above changes, after giving the specific JNK inhibitor SP600125, were also studied. Results Compared with the mice in control group, the PD mice had the typical behaviors of PD. The number of TH-positive neurons in SN and the level of TH in SN of the midbrain in the model group were distinctly reduced by about 65% and 75% （P 〈0. 001 ）. Meanwhile, the number of Cox-2, caspase-3 immunoreactive cells in SN area and the expression level of Cox-2, caspase-3 and p-c-Jun in SN of the midbrain increased markedly. Especially, p-c-Jun was mainly expressed in the nucleus in SN area. In JNK inhibitor SP600125 group, the PD mice administrated by SP600125 had slight behavioral symptoms, the number of TH-positive neurons in SN and the expression level of TH were decreased by only 15% and 25% as compared with the control group （ P 〈 0. 001 ）. The number of Cox-2 and caspase-3 positive cells were clearly reduced as compared With the model group （ P 〈 0. 001 ）, Meanwhile, p-c-Jun was mainly expressed in the cytoplasm of nigral neurons. The expression level of Cox-2, caspase-3 and p-c-Jun in SN of the midbrain was obviously down-regulated as compared with PD mice. Conclusions JNK signaling pathway may play an important role in mediating neuroinflammation and apoptosis in SN in the mouse model of subacute PD induced by MPTP,and the specific JNK inhibitor SP600125 is neuroprotective to the mouse model.