Investigation of the therapeutic potential of N-acetyl cysteine and the tools used to define nigrostriatal degeneration in vivo.
Investigation of the therapeutic potential of N-acetyl cysteine and the tools used to define nigrostriatal degeneration in vivo.
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DOI：
10.1016/j.taap.2016.02.010
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发表时间：
2016-04-01
影响因子：
3.8
通讯作者：
Leak RK
中科院分区：
文献类型：
--
作者：
Nouraei N;Zarger L;Weilnau JN;Han J;Mason DM;Leak RK
谷胱甘肽前体N-乙酰-L-半胱氨酸(NAC)目前正在帕金森患者身上进行神经保护特性测试。我们的研究表明，NAC在体外可以通过谷胱甘肽不依赖的方式产生保护作用。因此，本研究的目标是建立一种NAC介导的保护动物模型，以剖析其潜在的机制。小鼠纹状体内注射氧化神经毒物6-羟基多巴胺(6-OHDA；4μg)，同时给予NAc(100 mg/kg)。6-OHDA后10d，NAC处理组大鼠纹状体内多巴胺能终末标志物酪氨酸羟化酶(TH)水平升高。由于TH的表达受到应激诱导的调节，我们将示踪剂荧光金注入纹状体以逆行标记黑质纹状体投射神经元。正如预期的那样，黑质荧光金染色和荧光金阳性图谱的细胞计数都是比仅依靠TH的测量更敏感的黑质纹状体退行性变的指标。然而，NAC不能保护6-OHDA后3周的多巴胺能神经元，四项指标证实了这一效果：纹状体TH水平、黑质TH水平、黑质TH+细胞计数和黑质荧光金水平。FuoroGold和NAC有一定程度的轻微毒性，这表明在依赖FuoroGold作为神经元计数工具以及设计长期服用NAC的实验时必须谨慎--例如对慢性疾病患者的临床试验。最后，讨论了用于定义黑质纹状体退行性变的工具的优点和局限性。
The glutathione precursor N-acetyl-L-cysteine (NAC) is currently being tested on Parkinson's patients for its neuroprotective properties. Our studies have shown that NAC can elicit protection in glutathione-independent manners in vitro. Thus, the goal of the present study was to establish an animal model of NAC-mediated protection in which to dissect the underlying mechanism. Mice were infused intrastriatally with the oxidative neurotoxicant 6-hydroxydopamine (6-OHDA; 4 μg) and administered NAC intraperitoneally (100 mg/kg). NAC-treated animals exhibited higher levels of the dopaminergic terminal marker tyrosine hydroxylase (TH) in the striatum 10d after 6-OHDA. As TH expression is subject to stress-induced modulation, we infused the tracer FluoroGold into the striatum to retrogradely label nigrostriatal projection neurons. As expected, nigral FluoroGold staining and cell counts of FluoroGold+ profiles were both more sensitive measures of nigrostriatal degeneration than measurements relying on TH alone. However, NAC failed to protect dopaminergic neurons 3 weeks following 6-OHDA, an effect verified by four measures: striatal TH levels, nigral TH levels, nigral TH+ cell counts, and nigral FluoroGold levels. Some degree of mild toxicity of FluoroGold and NAC was evident, suggesting that caution must be exercised when relying on FluoroGold as a neuron-counting tool and when designing experiments with long-term delivery of NAC—such as clinical trials on patients with chronic disorders. Finally, the strengths and limitations of the tools used to define nigrostriatal degeneration are discussed.