目的:探讨纹状体细胞外信号调节激酶(Erk1/2)及其磷酸化(p-Erk1/2)在有氧训练中减轻L-DOPA诱导的PD小鼠运动障碍(LID)的作用。
方法:48只雄性C57BL/6N小鼠随机分为6-OHDA手术组(6-OHDA,n=42)和假手术组(Sham,n=6)。将6-OHDA两点注射入右侧纹状体以建立侧向损伤PD模型。PD小鼠随机分为PD对照组(PD,n=13)和PD运动组(PDE,n=16),接下来是4周的L-DOPA治疗,和PDE小鼠同时接受跑表训练(18m/min,40min/day,5次/周)。每周进行AIM评分,4周后使用旋转棒评估小鼠的运动功能,开放领域,和步态测试。免疫组织化学用于检测黑质纹状体TH表达,Westernblot检测Erk1/2和p-Erk1/2蛋白表达,免疫荧光双标记技术用于检测Erk1/2和p-Erk1/2与强啡肽(PDYN)的共表达。
结果:(1)随着L-DOPA治疗时间的延长,PD和PDE小鼠的所有AIM评分均显着增加(P<0.05)。与PD相比,PDE小鼠AIM评分均显著降低(P<0.05)。(2)4周后,与Sham相比,PD小鼠的运动功能明显降低(P<0.05或P<0.01);与PD相比,PDE小鼠运动功能显著增强(P<0.05)。(3)与Sham相比,Erk1/2蛋白的表达,PD小鼠Erk1/2和p-Erk1/2的阳性细胞数以及与PDYN共表达的阳性细胞数明显增加(P<0.05);与PD相比,Erk1/2蛋白在PDE小鼠中表达显著降低(P<0.05),Erk1/2和p-Erk1/2阳性细胞数明显减少(P<0.05)。
结论:4周有氧运动可有效缓解L-DOPA诱导的PD小鼠运动障碍的发展,改善运动功能。相关机制可能与有氧运动抑制纹状体Erk/MAPK信号通路过度激活有关,但这种变化在D1-MSN中没有选择性发生。
OBJECTIVE: To investigate the role of the striatal extracellular signal-regulated kinase (Erk1/2) and its phosphorylation (p-Erk1/2) in aerobic training to alleviate the development of the L-DOPA induced dyskinesia (LID) in PD mice.
METHODS: Forty-eight male C57BL/6 N mice were randomly divided into the 6-OHDA surgery group (6-OHDA, n=42) and the sham surgery group (Sham, n=6). A two-point injection of 6-OHDA into the right striatum was used to establish a lateralized injury PD model. PD mice were randomly divided into a PD control group (PD, n=13) and a PD exercise group (PDE, n=16), this is followed by 4 weeks of L-DOPA treatment, and PDE mice received concurrent running table training (18 m/min, 40 min/day, 5 times/week). AIM scores were performed weekly, and mice were assessed for motor function after 4 weeks using the rotarod, open field, and gait tests. Immunohistochemistry was used to test nigrostriatal TH expression, Western blot was used to determine Erk1/2 and p-Erk1/2 protein expression, and immunofluorescence double-labeling technique was used to detect Erk1/2 and p-Erk1/2 co-expression with prodynorphin (PDYN).
RESULTS: (1) All AIM scores of PD and PDE mice increased significantly (P < 0.05) with the prolongation of L-DOPA treatment. Compared with PD, all AIM scores were significantly lower in PDE mice (P < 0.05). (2) After 4 weeks, the motor function of PD mice was significantly reduced compared with Sham (P < 0.05 or P < 0.01); compared with PD, the motor function of PDE mice was significantly increased (P < 0.05). (3) Compared with Sham, the expression of Erk1/2 protein, the number of positive cells of Erk1/2 and p-Erk1/2 and the number of positive cells co-expressed with PDYN were significantly increased in PD mice (P < 0.05); compared with PD, Erk1/2 protein expression was significantly decreased in PDE mice (P < 0.05), and the number of Erk1/2 and p-Erk1/2 positive cells was significantly reduced (P < 0.05).
CONCLUSIONS: 4 weeks of aerobic exercise can effectively alleviate the development of L-DOPA-induced dyskinesia and improve motor function in PD mice. The related mechanism may be related to the inhibition of striatal Erk/MAPK signaling pathway overactivation by aerobic exercise, but this change did not occur selectively in D1-MSNs.