Unit of Molecular Neurobiology, Department of Biochemistry, University of Madras, Guindy Campus, Chennai, 600 025, Tamilnadu, India.
J Chem Neuroanat. 2020 Jul;106:101788. doi: 10.1016/j.jchemneu.2020.101788. Epub 2020 Apr 9.
Persuasive evidence propose that the toxicity of dopamine in parkinsonism and the loss of dopaminergic neurons are the earliest events during the pathogenesis of Parkinson's disease (PD). In our earlier study, Asiaticoside (AS), a triterpenoid saponin isolated from Centella asiatica was shown to exert a neuroprotective effect against hemiparkinsonism, purportedly due to phosphoinositides (PI)-assisted cytodynamics and synaptic function. Here, we evaluate AS in the modulation of dopamine (DA), mitochondrial integrity and neurite variations in vitro and motor dysfunctions in vivo. PC12 cells challenged with rotenone-(ROT) (0.1 μM/mL) were exposed to AS and l-DOPA (10 mM and 20 μM/mL respectively). The protein expressions of Bax and Bcl-2 that regulate cell death were assessed following neurite length assays. Rats were distributed into 6 groups (6 rats/group): Sham, Vehicle controls, ROT-infused (6 μg/μl/kg), AS- treated (50 mg/kg/day), Drug control, and ROT + L-DOPA-treated (6 mg/kg/day) groups. At the end of the experimental period, the rats were sacrificed after performing motor behavioral analysis, and the striatum was dissected out. The contents of synaptic vesicular and cytosolic DA were analyzed. Further, the levels of striatal PI were also measured. ROT had caused significant reduction in the neurite outgrowth in the exposed PC12 cells while the tested concentrations of AS and l-DOPA can exert their protective effect on the stunted neurite growth. The levels of Bax, Bcl-2, and cytochrome c which were significantly disturbed by ROT, could also be affected by AS thereby suggesting its effect on neurons. AS treatment caused an improved motor performance, vesicular and cytosolic DA, and striatal PI. These pre-clinical findings force us to speculate that AS could be a potential drug candidate in combating ROT-induced variations that are possibly precipitated by varied vesicular trafficking of DA.
有说服力的证据表明，帕金森病（PD）发病机制中多巴胺的毒性和多巴胺能神经元的丧失是最早的事件。在我们之前的研究中，从积雪草中分离得到的三萜皂苷积雪草苷（AS）被证明对偏侧帕金森病具有神经保护作用，据称这是由于磷酯酰肌醇（PI）辅助细胞动力学和突触功能。在这里，我们评估了 AS 对多巴胺（DA）、线粒体完整性和神经突变化的体外调节作用以及体内运动功能障碍。用鱼藤酮（ROT）（0.1 μM/mL）处理 PC12 细胞后，将 AS 和左旋多巴（10 mM 和 20 μM/mL）分别暴露于 AS 和左旋多巴。用神经突长度测定法评估了调节细胞死亡的 Bax 和 Bcl-2 的蛋白表达。将大鼠分为 6 组（每组 6 只）：假手术组、对照组、ROT 输注组（6 μg/μl/kg）、AS 治疗组（50 mg/kg/天）、药物对照组和 ROT+L-DOPA 治疗组（6 mg/kg/天）。在实验期末，进行运动行为分析后处死大鼠，取出纹状体。分析突触小泡和细胞质 DA 的含量。此外，还测量了纹状体 PI 的水平。ROT 导致暴露的 PC12 细胞中的神经突生长显著减少，而测试浓度的 AS 和左旋多巴可以对生长不良的神经突生长发挥保护作用。ROT 明显扰乱的 Bax、Bcl-2 和细胞色素 c 的水平也可以被 AS 影响，从而表明其对神经元的影响。AS 治疗可改善运动表现、囊泡和细胞质 DA 以及纹状体 PI。这些临床前发现迫使我们推测 AS 可能是一种潜在的候选药物，可用于对抗 ROT 诱导的多巴胺囊泡转运变化。
