Leal Rodrigo B, Ribeiro Sandro José, Posser Thaís, Cordova Fabiano M, Rigon Ana Paula, Zaniboni Filho Evoy, Bainy Afonso C D
Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil.
Aquat Toxicol. 2006 Apr 20;77(1):98-104. doi: 10.1016/j.aquatox.2005.11.002. Epub 2005 Dec 19.
Lead (Pb2+) is a neurotoxic trace metal, widespread in aquatic environment that can change physiologic, biochemical and behavioral parameters in diverse fish species. Chemical exposure may drive modulation of mitogen-activated protein kinases (MAPKs) that are a family of highly conserved enzymes which comprise ubiquitous groups of signaling proteins playing critical regulatory roles in cell physiology. Extracellular signal-regulated kinases (ERK1/2) and p38(MAPK) control complex programs such as gene expression, embryogenesis, cell differentiation, cell proliferation, cell death and synaptic plasticity. Little information is available about MAPKs in aquatic organisms and their modulation by trace metals. The aim of this work was to determine the modulation of ERK1/2 and p38(MAPK) phosphorylation by Pb2+ in vivo and in vitro, in cerebellar slices of the catfish, Rhamdia quelen. In the in vitro model, slices were incubated for 3 h with lead acetate (1-10 microM). In the in vivo studies, the animals were exposed for 2 days to lead acetate (1 mg L(-1)). ERK1/2 and p38(MAPK) (total and phosphorylated forms) were immunodetected in cerebellar slices by Western blotting. Pb2+ added in vitro at 5 and 10 microM increased significantly the phosphorylation of both MAPKs. The in vivo exposed animals also showed a significant increase of ERK1/2 and p38(MAPK) phosphorylation without changes in the total content of the enzymes. In conclusion, the present work indicates that it is possible to evaluate the ERK1/2 and p38(MAPK) activation in the central nervous system (CNS) of a freshwater fish largely distributed in South America. Moreover, Pb2+, an important environmental pollutant may activate in vitro and in vivo ERK1/2 and p38(MAPK) enzymes. These findings are important considering the functional and ecologic implications associated to Pb2+ exposure of a freshwater fish species, such as R. quelen, and the roles of ERK1/2 and p38(MAPK) in the control of brain development, neuroplasticity and cell death.
铅（Pb2+）是一种具有神经毒性的痕量金属，广泛存在于水生环境中，能够改变多种鱼类的生理、生化和行为参数。化学物质暴露可能会促使丝裂原活化蛋白激酶（MAPKs）发生调节，MAPKs是一类高度保守的酶家族，由在细胞生理学中发挥关键调节作用的普遍存在的信号蛋白组成。细胞外信号调节激酶（ERK1/2）和p38（MAPK）控制着诸如基因表达、胚胎发育、细胞分化、细胞增殖、细胞死亡和突触可塑性等复杂程序。关于水生生物中的MAPKs及其受痕量金属调节的信息很少。本研究的目的是在体内和体外确定Pb2+对鲶鱼（Rhamdia quelen）小脑切片中ERK1/2和p38（MAPK）磷酸化的调节作用。在体外模型中，将切片与醋酸铅（1-10 microM）孵育3小时。在体内研究中，动物暴露于醋酸铅（1 mg L(-1)）2天。通过蛋白质免疫印迹法在小脑切片中免疫检测ERK1/2和p38（MAPK）（总形式和磷酸化形式）。体外添加5和10 microM的Pb2+可显著增加两种MAPKs的磷酸化。体内暴露的动物也显示出ERK1/2和p38（MAPK）磷酸化显著增加，而酶的总含量没有变化。总之，本研究表明，有可能评估分布于南美洲的一种淡水鱼中枢神经系统（CNS）中的ERK1/2和p38（MAPK）的激活情况。此外，重要的环境污染物Pb2+可能在体外和体内激活ERK1/2和p38（MAPK）酶。考虑到与淡水鱼物种（如R. quelen）暴露于Pb2+相关的功能和生态影响，以及ERK1/2和p38（MAPK）在控制大脑发育、神经可塑性和细胞死亡中的作用，这些发现具有重要意义。
