Laboratory of Biochemistry and Toxicology, School of Veterinary Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Toxicol Appl Pharmacol. 2011 Nov 1;256(3):330-6. doi: 10.1016/j.taap.2011.06.002. Epub 2011 Jun 17.
Previous work in our laboratory has shown that sub-lethal concentrations (1-10 μM) of chlorpyrifos (CPF), diazinon (DZ) and diazinon oxon (DZO) inhibit the outgrowth of axon-like neurites in differentiating mouse N2a neuroblastoma cells concomitant with altered levels and/or phosphorylation state of axonal cytoskeleton and growth-associated proteins. The aim of the present work was to determine whether chlorpyrifos oxon (CPO) was capable of inhibiting N2a cell differentiation in a similar manner. Using experimental conditions similar to our previous work, sub-lethal concentrations (1-10 μM) of CPO were found to inhibit N2a cell differentiation. However, unlike previous studies with DZ and DZO, there was a high level of sustained inhibition of acetylcholinesterase (AChE) in CPO treated cells. Impairment of neurite outgrowth was also associated with reduced levels of growth associated protein-43 and neurofilament heavy chain (NFH), and the distribution of NFH in cells stained by indirect immunofluorescence was disrupted. However, in contrast to previous findings for DZO, the absolute level of phosphorylated NFH was unaffected by CPO exposure. Taken together, the findings suggest that sub-lethal concentrations of CPO inhibit axon outgrowth in differentiating N2a cells and that this effect involves reduced levels of two proteins that play key roles in axon outgrowth and maintenance. Although the inhibition of neurite outgrowth is unlikely to involve AChE inhibition directly, further work will help to determine whether the persistent inhibition of AChE by CPO can account for the different effects induced by CPO and DZO on the levels of total and phosphorylated NFH.
先前我们实验室的工作表明，低浓度（1-10 μM）的毒死蜱（CPF）、二嗪农（DZ）和二嗪农氧（DZO）能够抑制分化中的鼠 N2a 神经母细胞瘤细胞的轴突样神经突的生长，同时改变轴突细胞骨架和生长相关蛋白的水平和/或磷酸化状态。本研究的目的是确定氧乐果（CPO）是否能够以类似的方式抑制 N2a 细胞分化。在与我们之前的工作类似的实验条件下，发现低浓度（1-10 μM）的 CPO 能够抑制 N2a 细胞分化。然而，与先前 DZ 和 DZO 的研究不同，CPO 处理的细胞中乙酰胆碱酯酶（AChE）持续受到高度抑制。神经突生长受损也与生长相关蛋白-43 和神经丝重链（NFH）水平降低有关，间接免疫荧光染色的细胞中 NFH 的分布也受到破坏。然而，与先前 DZO 的发现相反，CPO 暴露对 NFH 的磷酸化水平没有影响。综上所述，研究结果表明，低浓度的 CPO 抑制分化中的 N2a 细胞的轴突生长，这种作用涉及到两种在轴突生长和维持中起关键作用的蛋白质水平降低。尽管神经突生长的抑制不太可能直接涉及 AChE 抑制，但进一步的研究将有助于确定 CPO 对 AChE 的持续抑制是否可以解释 CPO 和 DZO 对总 NFH 和磷酸化 NFH 水平产生的不同影响。
