Tetrahydroisoquinoline (TIQ) derivatives are putative neurotoxins that may contribute to the degeneration of dopaminergic neurons in Parkinson's disease. One TIQ, norsalsolinol (NorSAL), is present in dopamine-rich areas of human brain, including the substantia nigra. Here, we demonstrate that NorSAL reduces cell viability and induces apoptosis via cytochrome c release and caspase 3 activation in SH-SY5Y human neuroblastoma cells. Cytochrome c release, caspase 3 activation, and apoptosis induction were all inhibited by the antioxidant N-acetylcysteine. Thus, reactive oxygen species (ROS) contribute to apoptosis induced by NorSAL. Treatment with NorSAL also increased levels of oxidative damage to DNA, a stimulus for apoptosis, in SH-SY5Y. To clarify the mechanism of intracellular DNA damage, we examined the DNA damage caused by NorSAL using (32)P-5'-end-labeled isolated DNA fragments. NorSAL induced DNA damage in the presence of Cu(II). Catalase and bathocuproine, a Cu(I) chelator, inhibited this DNA damage, suggesting that ROS such as the Cu(I)-hydroperoxo complex derived from the reaction of H(2)O(2) with Cu(I), promote DNA damage by NorSAL. In summary, NorSAL-generated ROS induced oxidative DNA damage, which led to caspase-dependent apoptosis in neuronal cells.

中文翻译：

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Norsalsolinol（一种与帕金森氏病有关的内源性四氢异喹啉衍生物）诱导的氧化DNA损伤和细胞凋亡的机制。

四氢异喹啉（TIQ）衍生物是可能导致帕金森氏病多巴胺能神经元变性的推定神经毒素。一种TIQ，norsalsolinol（NorSAL），存在于人脑多巴胺丰富的区域，包括黑质。在这里，我们证明，NorSAL降低细胞活力，并通过SH-SY5Y人成神经细胞瘤细胞中的细胞色素c释放和caspase 3激活诱导凋亡。抗氧化剂N-乙酰半胱氨酸抑制细胞色素c的释放，caspase 3的活化和细胞凋亡的诱导。因此，活性氧（ROS）有助于NorSAL诱导的细胞凋亡。用NorSAL进行的处理还增加了SH-SY5Y中DNA的氧化损伤水平，DNA是细胞凋亡的刺激物。为了阐明细胞内DNA损伤的机制，我们使用（32）P-5'-末端标记的分离的DNA片段检查了由NorSAL引起的DNA损伤。在Cu（II）存在下，NorSAL诱导DNA损伤。过氧化氢酶和铜脲（Cu（I）螯合剂）抑制这种DNA损伤，表明ROS（例如H（2）O（2）与Cu（I）反应衍生的Cu（I）-hydroperoxo络合物）促进DNA NorSAL造成的损害。总之，NorSAL产生的ROS诱导了DNA的氧化损伤，从而导致神经元细胞中caspase依赖性凋亡。