Cordova Fabiano M, Rodrigues Ana Lúcia S, Giacomelli Maria B O, Oliveira Camila S, Posser Thaís, Dunkley Peter R, Leal Rodrigo B
Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, SC, 88040-900, Florianópolis, Brazil.
Brain Res. 2004 Feb 13;998(1):65-72. doi: 10.1016/j.brainres.2003.11.012.
Lead (Pb(2+)) is widely recognized as a neurotoxicant whose mechanisms of action are not completely established. We have previously demonstrated that Pb(2+) can activate the p38(MAPK) pathway and increase the phosphorylation of Hsp27 in bovine adrenal chromaffin cells and human SH SY5Y cells over a short incubation period (1 h). In the present work we analyzed the effects of Pb(2+) administered in vivo on the level and the phosphorylation state of ERK1/2 and p38(MAPK) in the hippocampus of immature rats. Rats were treated with lead acetate (2, 8 or 12 mg/kg, i.p.) or saline (control) over the 8th to 12th postnatal days, and hippocampal slices were prepared on the 14th day. The Pb(2+) level in the lead-treated animals increased 2.5-6-fold in the blood (3.0-6.0 microg/dl) and 2.0-3.0-fold in the forebrain (78-103 ng/g wet weight), compared to control (saline). The phosphorylation of both ERK1/2 and p38(MAPK) was significantly increased by prior exposure to Pb(2+) in vivo. In in vitro experiments, hippocampal slices from 14-day-old rats were exposed to Pb(2+) (1-10 microM) for 1 and 3 h. There were no changes in the phosphorylation state of ERK and p38(MAPK) for 1-h incubation, whereas a significant increase of ERK1/2 and p38(MAPK) phosphorylation by Pb(2+) (5 microM) was observed for the 3-h incubation. Cell viability measured using MTT was not modified in any of the conditions tested. These results indicate that the phosphorylation of hippocampal ERK1/2 and p38(MAPK) is stimulated by lead in a period of rapid brain development, an effect that may underlie, at least in part, the neurotoxicty elicited by this metal.
铅（Pb(2+)）被广泛认为是一种神经毒物，其作用机制尚未完全明确。我们之前已经证明，在短时间孵育（1小时）内，Pb(2+)可激活牛肾上腺嗜铬细胞和人SH SY5Y细胞中的p38(MAPK)通路并增加Hsp27的磷酸化。在本研究中，我们分析了体内给予Pb(2+)对未成熟大鼠海马中ERK1/2和p38(MAPK)水平及磷酸化状态的影响。在出生后第8至12天，用醋酸铅（2、8或12 mg/kg，腹腔注射）或生理盐水（对照）处理大鼠，并在第14天制备海马切片。与对照组（生理盐水）相比，铅处理动物血液中的Pb(2+)水平增加了2.5至6倍（3.0至6.0微克/分升），前脑中增加了2.0至3.0倍（78至103纳克/克湿重）。体内预先暴露于Pb(2+)可显著增加ERK1/2和p38(MAPK)的磷酸化。在体外实验中，将14日龄大鼠的海马切片暴露于Pb(2+)（1至10微摩尔）1小时和3小时。孵育1小时时，ERK和p38(MAPK)的磷酸化状态没有变化，而孵育3小时时，观察到Pb(2+)（5微摩尔）可显著增加ERK1/2和p38(MAPK)的磷酸化。在任何测试条件下，使用MTT测量的细胞活力均未改变。这些结果表明，在大脑快速发育期间，铅可刺激海马ERK1/2和p38(MAPK)的磷酸化，这种作用可能至少部分是该金属引发神经毒性的基础。
