孕哺期铝暴露对仔鼠海马LTP及Glu含量影响

Effect of aluminum on LTP and glutamate level in hippocampus of offsprings through exposure during pregnancy and lactation

目的研究孕哺期染铝对仔鼠长时程增强(LTP)和谷氨酸(Glu)含量影响,探讨铝对发育中中枢神经系统毒性作用及机制。方法 Wistar大鼠怀孕起染AlCl3至仔鼠哺乳期结束,共计6周,原子吸收石墨炉法测定血铝和脑铝含量;细胞外微电极技术测定LTP;免疫组化法测定海马谷氨酸含量。结果 0.2%AlCl3组仔鼠血铝和脑铝分别为(47.43±14.38)mg/L、(13.86±6.60)mg/g;0.4%AlCl3组血铝和脑铝为(55.56±19.07)mg/L、(18.79±5.18)mg/g,与对照组[(33.89±8.74)mg/L,(7.61±3.44)mg/g]比较,血铝、脑铝含量均明显增加(P<0.05);CA1区LTP的诱导和维持明显受到抑制,其群体峰电位幅值增强率明显低于对照组(P<0.01)。孕哺期铝暴露使仔鼠海马内谷氨酸含量下降(P<0.05)。CA1区对照组,0.2%AlCl3组和0.4%AlCl3组谷氨酸平均吸光度(A)值分别为(0.35±0.02)、(0.33±0.02)、(0.29±0.03),阳性面积比分别为(5.06±1.36)、(4.70±0.56)、(1.71±0.23)。结论孕哺期铝暴露可以使仔鼠海马CA1区LTP的诱导和维持受到抑制,谷氨酸水平下降。

Objective To study the effect of aluminum on long-term potential（LTP） and glutamate level in hippocampus in newborns through exposure during pregnancy and lactation and to explore the mechanism by which aluminum impairs central nervous system development.Methods Wistar pregnant rats were administrated with aluminium chloride at the doses of 0,0.2%,and 0.4% for 6 weeks.Aluminum concentration in blood and brain was determined by atomic absorption spectrophotometer（AAS）.Extracellular microelectrode recording was used to detect the effect of aluminum on LTP in hippocampal CA1 area.Glutamate level was detected using immunohistochemical method.Results Blood aluminum and brain aluminum in 0.2% AlCl3-treated rats were 47.43±14.38 mg/L,13.86±6.60 mg/g and 55.56±19.07 mg/L,18.79±5.18 mg/g in 0.4% AlCl3-treated rats,which all increased significantly compared with those in control rats（33.89±8.74 mg/L and 7.61±3.44 mg/g）,（P0.05 for all）.The induction and maintenance of LTP were suppressed in aluminum-exposed rats.The population spike（PS） enhancement rate decreased significantly compared with that of the control（P0.01）.Aluminum exposure during pregnancy and lactation reduced glutamate level significantly in hippocampus（P0.05）.Absorption and positive area ratio of glutamate of CA1 region in the control,0.2% AlCl3,and 0.4% AlCl3 were 0.35±0.02,0.33±0.02,0.29±0.03 and 5.06±1.36,4.70±0.56,1.71±0.23,respectively.Conclusion Aluminum exposure during pregnancy and lactation could inhibit the induction and maintenance of LTP in newborn rats and reduce the level of glutamate.