铝对大鼠海马ERK蛋白及mRNA表达影响

目的研究慢性铝中毒对大鼠海马细胞外信号调节蛋白激酶（ERK）蛋白及mRNA表达水平的变化，探讨铝中毒对学习记忆机制的影响。方法选择断乳后Wistar大鼠，用不同浓度AlCl3的水饲养3个月。测量大鼠海马长时程增强（LTP），用改良的Takai法测定丝裂原活化蛋白激酶（MAPK）活性的变化。蛋白印迹（Western blotting）方法检测ERK1／2的蛋白含量，RT-PCR方法检测ERK2的mRNA表达。结果（1）各染铝组MAPK活性降低且与对照组比较差异有统计学意义（P〈0．05）；（2）ERK1／2蛋白表达的比较：①ERK2在大鼠海马中的蛋白含量高于ERK1；②染铝组ERK1／2非磷酸水平与对照组比较均有所下降（P〈0．05），但染铝组之间差异无统计学意义（P〉0．05）；③染铝组ERK1／2磷酸化水平与对照组的比较均有下降（P〈0．05），染铝组之间的差异有统计学意义（P〈0．05）。（3）染铝组ERK2的mRNA表达与对照组比较明显降低，但染铝组之间差异无统计学意义（P〉0．05）。结论慢性铝中毒不仅影响大鼠海马中ERK2的mRNA表达水平，同时也影响ERK1／2的蛋白表达水平的降低，造成有丝分裂原活化蛋白激酶（MAPK）活性的下降，损害LTP的形成，从而影响学习记忆功能下降。

Effect of chronic aluminium exposure on protein and mRNA expression of ERKs in hippocampus of rats

Objective To study the changes of Extracellular Signal Regulated Kinase(ERK)content and its mRNA expression level that caused by chronicaluminium exposure,which can alter the amplitude value of long-term potentiation(LTP),to go deep into the mechanism of learning and memory.Methods The ablactated Wistar rats were used to establish the chronic-aluminium exposed models by the gavage of AlCl_3 of different concentrations in the drinking water and LTP in hippocampus of rats was measured.The mitogen-activiated protein kinase(MAPK)activity was determined by modified Takai Method.ERK1/2 content of hippocampus and the mRNA expression level of ERK2were determined by Western Blot and RT-PCR methods individually.Results(1)The MAPK activity of AlCl_3 exposed groups was obviously lower than that of control groups(P<0.05).(2)The content of ERK1/2 in the hippocampus of AlCl_3-exposed groups fell down comparing with that of control groups but there was no statistic difference between the AlCl_3-exposed groups(P>0.05).(3)The amount of ERK2 was higher than that of ERK1 in the nervous system and the expression of ERK2 protein of aluminium exposed groups showed a downwards tendency comparing with that of control groups(P<0.05).(4)ERK1/2 phosphorylation level of aluminium exposed groups obviously decreased comparing with that of control group(P<0.05).(5)The mRNA expression of ERK2 of AlCl_3-exposed groups fell down comparing with that of control groups but there was no statistic difference between the AlCl_3-exposed groups(P>0.05).Conclusion Chronic aluminum exposure can affect not only the mRNA expression of ERK2 but also the expression of ERK1/2 protein and its phosphorylation level,in hence,can reduce the activity of MAPK,damaging the formation of LTP and consequently impairing the ability of learning and memory.