Audesirk T, Shugarts D, Cabell-Kluch L, Wardle K
Department of Biology, University of Colorado at Denver, USA.
Cell Biol Toxicol. 1995 Feb;11(1):1-10. doi: 10.1007/BF00769987.
Triethyl lead is the major metabolite of tetraethyl lead, which is used in industrial processes and as an antiknock additive to gasoline. We tested the hypothesis that low levels of triethyl lead (0.1 nmol/L to 5 mumol/L) interfere with the normal development of cultured E18 rat hippocampal neurons, possibly through increases in intracellular free calcium ion concentration, [Ca2+]in. The study assessed survival and differentiation using morphometric analysis of individual neurons. We also looked at short-term (up to 3.75-h) changes in intracellular calcium using the calcium-sensitive dye fura-2. Survival of neurons was significantly reduced at 5 mumol/L, and overall production of neurites was reduced at > or = 2 mumol/L. The length of axons and the number of axons and dendrites were reduced at > or = 1 mumol/L. Neurite branching was inhibited at 10 nmol/L for dendrites and 100 nmol/L for axons. Increases in intracellular calcium were observed during a 3.75-h exposure of newly plated neurons to 5 mumol/L triethyl lead. These increases were prevented by BAPTA-AM; which clamps [Ca2+]in at about 100 nmol/L. Culturing neurons with BAPTA-AM and 5 mumol/L triethyl lead did not reverse the effects of triethyl lead, suggesting that elevation of [Ca2+]in is not responsible for decreases in survival and neurite production. Triethyl lead has been shown to disrupt cytoskeletal elements, particularly neurofilaments, at very low levels, suggesting a possible mechanism for its inhibition of neurite branching at nanomolar concentrations.
三乙基铅是四乙基铅的主要代谢产物，四乙基铅用于工业生产过程及作为汽油的抗爆添加剂。我们检验了这样一个假设：低水平的三乙基铅（0.1纳摩尔/升至5微摩尔/升）可能通过增加细胞内游离钙离子浓度（[Ca2+]in）干扰培养的E18大鼠海马神经元的正常发育。该研究使用单个神经元的形态计量分析评估细胞存活和分化情况。我们还使用钙敏染料fura-2观察细胞内钙的短期（长达3.75小时）变化。5微摩尔/升时神经元存活率显著降低，≥2微摩尔/升时神经突的总体生成减少。≥1微摩尔/升时轴突长度、轴突和树突数量减少。树突在10纳摩尔/升、轴突在100纳摩尔/升时神经突分支受到抑制。新接种的神经元在暴露于5微摩尔/升三乙基铅3.75小时期间观察到细胞内钙增加。BAPTA-AM可防止这种增加，它将[Ca2+]in钳制在约100纳摩尔/升。用BAPTA-AM和5微摩尔/升三乙基铅培养神经元并没有逆转三乙基铅的作用，这表明[Ca2+]in升高并非导致存活率和神经突生成降低的原因。已表明三乙基铅在极低水平就能破坏细胞骨架成分，尤其是神经丝，这提示了其在纳摩尔浓度下抑制神经突分支的一种可能机制。
