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

Objective To study the effect of aluminum on long-term potential(LTP) and glutamate level in hippocampus in new borns 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),(P< 0.05 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(P< 0.01).Aluminum exposure during pregnancy and lactation reduced glutamate level significantly in hippocampus (P< 0.05).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 new born rats and reduce the level of glutamate.