不同时期铅暴露对小鼠学习记忆能力及海马组织中β淀粉样蛋白表达的影响

Effects of lead exposure on learning and memory ability and β-amyloid protein level in hippocampus of mice at different age stages

目的：探讨不同时期铅暴露对小鼠学习记忆能力以及海马组织中β淀粉样蛋白（Aβ）表达的影响。方法：将40只健康雄性仔鼠随机分为生长期暴露组[母鼠饮2 g/L的醋酸铅水溶液经母乳给仔鼠染毒,直至断乳（21d）]、成年期暴露组（出生后第180-240天给予2 g/L的醋酸铅水溶液）、共同暴露组（按照上述方式在生长期及成年期均染铅）以及对照组（饮用去离子水）4组,每组10只。1 a后,分别用Morris水迷宫及ELISA测定各组小鼠的学习记忆能力以及海马组织中Aβ含量。结果：各组小鼠平均逃避潜伏期差异有统计学意义（F时间=396.688,F组间=177.902,P均〈0.001）;各暴露组小鼠穿越平台次数少于对照组（F=30.394,P〈0.001）,生长期暴露组和共同暴露组小鼠穿越平台的次数少于成年期暴露组（P均〈0.05）;各暴露组小鼠海马组织中Aβ含量高于对照组（F=346.032和53.796,P均〈0.001）,且生长期暴露组和共同暴露组Aβ含量高于成年期暴露组（P〈0.05）。结论：生长期铅暴露造成海马组织中Aβ蓄积更严重,小鼠学习记忆能力的损害也更严重。

Aim： To explore the effects of lead exposure on the ability of spatial learning and memory and β-amyloid protein（ Aβ） level in hippocampus of mice at different age stages. Methods： Healthy male mice were randomly allocated into growing exposure group（ drinking 2 g / L Pb containing water from birth to 21 days by breast milk）,adulthood exposure group（ drinking 2 g / L Pb containing water from 180 days to 240 days after birth）,joint exposure group（ lead exposed at growing period and adulthood） and control group（ drinking deionized water）,10 mice in each group. After 1 year,the spatial learning and memory ability was evaluated by Morris water maze（ MWM）,and the level of Aβ in hippocampus was measured by ELISA. Results： The escape latency in each group measured at different days had significant difference（ Ftime= 396. 688, P〈0. 001）,and there were also differences between different groups（ Fgroup= 177. 902, P〈0. 001）.And compared with the control group,the numbers of platform cross significantly decreased（ F = 30. 394, P〈0. 001）. The numbers of platform cross in the growing exposure group and the joint exposure group were less than the adulthood exposure group（ P〈0. 05）. The level of Aβ in hippocampus in lead exposure groups were significantly higher than that in control group（ F = 346. 032 and 53. 796, P〈0. 001）,and the levels of Aβ in both the growing exposure group and the joint exposure group was higher than that in the adulthood exposure group（ P〈0. 05）. Conclusion： Lead exposure can lead to the accumulation of Aβ in hippocampus and the damage of spatial learning and memory ability. These accumulation and damage are more severe when the mice get lead exposure in growing time.