促红细胞生成素通过c-Jun氨基末端激酶-e-Jun通路减轻脊髓神经元凋亡

Erythropoietin alleviates spinal neuron apoptosis via c-Jun N-terminal kinase-c-Jun pathway

目的探讨促红细胞生成素(EPO)对神经根性撕脱伤(RA)后神经元的保护机制.方法成年雄性Wistar大鼠63只,随机等分为对照组(C组:根性撕脱+隔日皮下注射生理盐水1ml)和促红细胞生成素组(E组:根性撕脱伤+隔日皮下注射EP0 1 000 U/kg).两组分别在苏醒后即刻、1、2、4、7、14 d留取脊髓C5~T1段,免疫组织化学法检测脊髓神经元内裂解的聚腺苷二磷酸核糖聚合酶(Cleaved-PARP)、磷酸化c-Jun氨基末端激酶(p-JNK)和c-Jun变化.应用SPSS 17.0统计软件分析,数据以均值±标准差(Mean±SD)表示,采用单因素方差分析.结果(1)E组Cleaved-PARP在第2天(3 173.3±153.1)、第4天(8 943.2±351.5)、第7天(7017.9±424.7)阳性A值比C组(10 575.1±594.3、12737.1±385.3、10 256.9±629.4)更低,差异有统计学意义(F=4 363.938、1587.489、545.925,P<0.01).(2)E组c-Jun的A值在第1~7天(1 351.2±253.7、2386.8±305.8、1 898.2±138.0、1547.1±163.9)明显低于C组(2 165.8±205.7、3378.1±272.5、2 835.2±166.8、2 579.8±264.8),差异有统计学意义(F=186.613、175.719、562.005、329.896,P<0.01).(3)组间比较,E组第1~4天p-JNK(1 407.1±121.7、1 925.6±126.6、4 892.3±330.2)明显低于C组(3041.5±139.6、9243.8±573.9、5 486.6±358.4),差异有统计学意义(F=2 336.447、4 651.806、44.617,P<0.01),达峰时间从第2天延迟到第4天.结论 EPO通过降低p-JNK、c-Jun水平,对脊髓神经元发挥抗凋亡作用.

Objective To study the neural protective mechanism of erythropoietin (EPO) following root avulsion (RA). MethodsSixty-three adult Wistar rats were randomly divided into two groups: control group (avulsion + 1 ml normal saline s. c. on alternate days), EPO-treated group (avulsion + 1 000 U/kg EPO s. c. on alternate days). The rats were sacrificed at 0 (after awake), 1, 2, 4, 7 and 14 days after avulsion for harvesting C5-T1 spinal samples. Immunohistochemistry was used to detect cleaved-poly adenosine diphosphate-ribose polymerase (Cleaved-PARP), c-Jun and phosphorylated c-Jun N-terminal kinase (p-JNK) in spinal neurons. Results(1) The expression of Cleaved-PARP was significantly decreased in EPO-treated group at 2, 4, and 7 days post-avulsion (3 173.3±153.1, 8 943.2±351.5 and 7 017.9±424.7) as compared with control group (10 575.1±594.3, 12 737.1±385.3 and 10 256.9±629.4)(F=4 363.938, 1 587.489, 545.925, P<0.01).(2) The expression of c-Jun in EPO-treated group was significantly lower at 1, 2, 4 and 7 day(s)(1 351.2±253.7, 2 386.8±305.8, 1 898.2±138.0 and 1 547.1±163.9) than in control group (2 165.8±205.7, 3 378.1±272.5, 2 835.2±166.8, 2 579.8±264.8)(F=186.613, 175.719, 562.005, 329.896, P<0.01).(3) The expression of p-JNK in EPO-treated group was significantly lower at 1, 2, 4 days after avulsion (1 407.1±121.7, 1 925.6±126.6 and 4 892.3±330.2) than in control group (3 041.5±139.6, 9 243.8±573.9 and 5 486.6±358.4)(F=2 336.447, 4 651.806, 44.617, P<0.01). The peak of p-JNK was postponed to 4th day in EPO-treated group as compared with 2nd day in control group. ConclusionDown-regulation of p-JNK and c-Jun is the anti-apoptosis mechanism of EPO for spinal neurons.