Walkinshaw G, Waters C M
Molecular Pharmacology and Toxicology Group, University of Manchester, School of Biological Sciences, U.K.
Neuroscience. 1994 Dec;63(4):975-87. doi: 10.1016/0306-4522(94)90566-5.
Death of neuronal cells during development and following deprivation of trophic factors is known to occur via an active mechanism requiring RNA and protein synthesis, known as apoptosis. Apoptosis is a form of cell "suicide" whereby the cell decides its own fate by activating a genetic programme of cell death. In contrast, necrosis is a passive uncontrolled form of cell death often observed in response to a toxic insult. Although it is known that neuronal cell death during development occurs by apoptosis, the mechanisms underlying neurotoxin-induced neuronal cell death remain poorly understood. In this study we have examined the mechanism by which 6-hydroxydopamine, a specific neurotoxin for catecholaminergic cells, induces neuronal cell death in vitro. We report that 6-hydroxydopamine induces cell death in the neuronal PC12 cell line via a mechanism which has the characteristic morphological and biochemical hallmarks of apoptosis. PC12 cells induced to die by 6-hydroxydopamine treatment exhibited cell shrinkage, classical chromatin condensation and membrane blebbing. Analysis of DNA integrity from 6-hydroxydopamine-treated cells revealed cleavage of DNA into regular sized fragments, a biochemical hallmark of apoptosis. 6-Hydroxydopamine-induced apoptosis of PC12 cells was suppressed by desipramine, a monoamine uptake inhibitor, suggesting that 6-hydroxydopamine is initiating apoptosis via a specific intracellular mechanism. Aurintricarboxylic acid, a general inhibitor of nucleases, also suppressed 6-hydroxydopamine-induced apoptosis, suggesting the involvement of an endonuclease in the death pathway. The aetiology of idiopathic Parkinson's disease remains uncertain, although evidence suggests that endogenous and/or exogenous toxins may initiate neuronal cell death in this disease. The dopaminergic neurotoxin 6-hydroxydopamine is used to generate animal models of Parkinson's disease in vivo. We have demonstrated that this neurotoxin kills neuronal cells in vitro by an active process of apoptosis. Thus, the possibility exists that cell death in neurodegenerative diseases such as Parkinsonism also occurs in an active manner initiated by as yet unidentified environmental or metabolic toxins. Cell death that involves activation of an apoptotic programme can be modulated by addition of extracellular trophic factors, and is also controlled by the levels of intracellular factors. If neurotoxin-induced apoptosis plays a role in Parkinson's disease the implication is that the neuronal degeneration may be prevented by pharmacological manipulations.
已知在发育过程中以及营养因子缺乏后，神经元细胞的死亡是通过一种需要RNA和蛋白质合成的主动机制发生的，即凋亡。凋亡是细胞“自杀”的一种形式，细胞通过激活细胞死亡的遗传程序来决定自身的命运。相比之下，坏死是一种被动的、不受控制的细胞死亡形式，通常在对毒性损伤的反应中观察到。虽然已知发育过程中神经元细胞死亡是通过凋亡发生的，但神经毒素诱导神经元细胞死亡的潜在机制仍知之甚少。在本研究中，我们研究了6-羟基多巴胺（一种儿茶酚胺能细胞的特异性神经毒素）在体外诱导神经元细胞死亡的机制。我们报告6-羟基多巴胺通过一种具有凋亡特征性形态和生化标志的机制在神经元PC12细胞系中诱导细胞死亡。经6-羟基多巴胺处理诱导死亡的PC12细胞表现出细胞收缩、典型的染色质浓缩和细胞膜起泡。对6-羟基多巴胺处理细胞的DNA完整性分析显示DNA裂解成规则大小的片段，这是凋亡的生化标志。单胺摄取抑制剂地昔帕明抑制了6-羟基多巴胺诱导的PC12细胞凋亡，表明6-羟基多巴胺通过一种特定的细胞内机制引发凋亡。核酸酶的通用抑制剂金精三羧酸也抑制了6-羟基多巴胺诱导的凋亡，表明一种核酸内切酶参与了死亡途径。特发性帕金森病的病因仍不确定，尽管有证据表明内源性和/或外源性毒素可能引发该疾病中的神经元细胞死亡。多巴胺能神经毒素6-羟基多巴胺用于在体内生成帕金森病的动物模型。我们已经证明这种神经毒素在体外通过凋亡的主动过程杀死神经元细胞。因此，在帕金森症等神经退行性疾病中，细胞死亡也可能以由尚未确定的环境或代谢毒素引发的主动方式发生。涉及凋亡程序激活的细胞死亡可以通过添加细胞外营养因子来调节，并且也受细胞内因子水平的控制。如果神经毒素诱导的凋亡在帕金森病中起作用，这意味着神经元变性可能通过药理学操作来预防。
