Shin Mi-Hyun, Jang Jung-Hee, Surh Young-Joon
Laboratory of Biochemistry and Molecular Toxicology, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea.
Free Radic Biol Med. 2004 May 1;36(9):1185-94. doi: 10.1016/j.freeradbiomed.2004.02.011.
Tetrahydropapaveroline (THP), a dopamine-derived tetrahydroisoquinoline catechol, has been suspected to be dopaminergic neurotoxin that elicits parkinsonism and neurobehavioral abnormalities associated with chronic alcoholism. THP has been detected in the brains of parkinsonian patients, and its urinary as well as brain level increases after l-3,4-dihydroxyphenylalanine treatment. Autoxidation or enzymatic oxidation of THP and subsequent generation of reactive oxygen species (ROS) may contribute to the degeneration of dopaminergic neurons induced by this tetrahydroisoquinoline alkaloid. In the present study, THP was found to elicit cytotoxicity in cultured rat pheochromocytoma (PC12) cells, which was completely blocked by reduced glutathione and N-acetyl-L-cysteine. THP-treated PC12 cells exhibited increased intracellular accumulation of ROS and underwent apoptosis as determined by poly(ADP-ribose)polymerase cleavage, an increased ratio of Bax to BclxL, terminal transferase-mediated dUTP nick end labeling, and nuclear fragmentation or condensation. THP treatment caused activation of the redox-sensitive transcription factor nuclear factor kappaB (NF-kappaB). Pretreatment of PC12 cells with NF-kappaB inhibitors, such as l-1-tosylamido-2-phenylethyl chloromethyl ketone and parthenolide, aggravated THP-induced cell death. THP treatment resulted in differential activation of mitogen-activated protein kinases as well as Akt/protein kinase B, thereby transmitting cell survival or death signals. In conclusion, THP induces apoptosis in PC12 cells by generating ROS. THP-mediated oxidative stress was accompanied by differential activation of intracellular signaling kinases and NF-kappaB.
四氢罂粟碱（THP）是一种由多巴胺衍生而来的四氢异喹啉儿茶酚，被怀疑是一种多巴胺能神经毒素，可引发帕金森症以及与慢性酒精中毒相关的神经行为异常。帕金森症患者的大脑中已检测到THP，在给予L-3,4-二羟基苯丙氨酸治疗后，其尿液及大脑中的水平会升高。THP的自氧化或酶促氧化以及随后活性氧（ROS）的生成可能导致这种四氢异喹啉生物碱诱导的多巴胺能神经元变性。在本研究中，发现THP在培养的大鼠嗜铬细胞瘤（PC12）细胞中引发细胞毒性，而还原型谷胱甘肽和N-乙酰-L-半胱氨酸可完全阻断这种毒性。经THP处理的PC12细胞表现出细胞内ROS积累增加，并发生凋亡，这可通过聚（ADP-核糖）聚合酶裂解、Bax与BclxL比例增加、末端脱氧核苷酸转移酶介导的dUTP缺口末端标记以及细胞核碎片化或凝聚来确定。THP处理导致氧化还原敏感转录因子核因子κB（NF-κB）激活。用NF-κB抑制剂（如L-1-甲苯磺酰氨基-2-苯乙基氯甲基酮和小白菊内酯）预处理PC12细胞会加重THP诱导的细胞死亡。THP处理导致丝裂原活化蛋白激酶以及Akt/蛋白激酶B的差异激活，从而传递细胞存活或死亡信号。总之，THP通过产生活性氧诱导PC12细胞凋亡。THP介导的氧化应激伴随着细胞内信号激酶和NF-κB的差异激活。
