Giordano Gennaro, Afsharinejad Zhara, Guizzetti Marina, Vitalone Annabella, Kavanagh Terrance J, Costa Lucio G
Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA.
Toxicol Appl Pharmacol. 2007 Mar;219(2-3):181-9. doi: 10.1016/j.taap.2006.09.016. Epub 2006 Oct 4.
Over the past several years evidence has been accumulating from in vivo animal studies, observations in humans, and in vitro studies, that organophosphorus (OP) insecticides may induce oxidative stress. Such effects may contribute to some of the toxic manifestations of OPs, particularly upon chronic or developmental exposures. The aim of this study was to investigate the role of oxidative stress in the neurotoxicity of two commonly used OPs, chlorpyrifos (CPF) and diazinon (DZ), their oxygen analogs (CPO and DZO), and their "inactive" metabolites (TCP and IMP), in neuronal cells from a genetic model of glutathione deficiency. Cerebellar granule neurons from wild type mice (Gclm +/+) and mice lacking the modifier subunit of glutamate cysteine ligase (Gclm -/-), the first and limiting step in the synthesis of glutathione (GSH), were utilized. The latter display very low levels of GSH and are more susceptible to the toxicity of agents that increase oxidative stress. CPO and DZO were the most cytotoxic compounds, followed by CPF and DZ, while TCP and IMP displayed lower toxicity. Toxicity was significantly higher (10- to 25-fold) in neurons from Gclm (-/-) mice, and was antagonized by various antioxidants. Depletion of GSH from Gclm (+/+) neurons significantly increased their sensitivity to OP toxicity. OPs increased intracellular levels of reactive oxygen species and lipid peroxidation and in both cases the effects were greater in neurons from Gclm (-/-) mice. OPs did not alter intracellular levels of GSH, but significantly increased those of oxidized glutathione (GSSG). Cytotoxicity was not antagonized by cholinergic antagonists, but was decreased by the calcium chelator BAPTA-AM. These studies indicate that cytotoxicity of OPs involves generation of reactive oxygen species and is modulated by intracellular GSH, and suggest that it may involve disturbances in intracellular homeostasis of calcium.
在过去几年中，来自体内动物研究、人体观察和体外研究的证据不断积累，表明有机磷（OP）杀虫剂可能会诱发氧化应激。这种效应可能导致OPs的一些毒性表现，尤其是在长期或发育性接触时。本研究的目的是调查氧化应激在两种常用OPs（毒死蜱（CPF）和二嗪农（DZ））、它们的氧类似物（CPO和DZO）以及它们的“无活性”代谢物（TCP和IMP）对谷胱甘肽缺乏遗传模型神经元细胞神经毒性中的作用。使用了野生型小鼠（Gclm +/+）和缺乏谷氨酸半胱氨酸连接酶调节亚基（Gclm -/-）的小鼠的小脑颗粒神经元，谷氨酸半胱氨酸连接酶是谷胱甘肽（GSH）合成的第一步也是限速步骤。后者的GSH水平极低，更容易受到增加氧化应激的药物的毒性影响。CPO和DZO是细胞毒性最强的化合物，其次是CPF和DZ，而TCP和IMP的毒性较低。Gclm（-/-）小鼠神经元中的毒性显著更高（10至25倍），并且被各种抗氧化剂所拮抗。从Gclm（+/+）神经元中耗尽GSH会显著增加它们对OP毒性的敏感性。OPs增加了细胞内活性氧和脂质过氧化水平，在这两种情况下，Gclm（-/-）小鼠神经元中的影响更大。OPs没有改变细胞内GSH水平，但显著增加了氧化型谷胱甘肽（GSSG）的水平。细胞毒性不受胆碱能拮抗剂的拮抗，但被钙螯合剂BAPTA-AM降低。这些研究表明，OPs的细胞毒性涉及活性氧的产生，并受细胞内GSH调节，表明其可能涉及细胞内钙稳态的紊乱。
