锌铅对大鼠子代生长发育和学习记忆的影响

目的:探讨宫内外铅锌暴露对大鼠子代生长发育和学习记忆的影响。方法:16只Wistar健康孕大鼠分为4组,正常对照组、高铅组、高锌组、高锌高铅组。从受孕第14 d起分别给予相应饲料及饮水,子代断乳后饲以与其母亲相同的饲料和饮水。于出生时、1 w、4 w、8 w时测体重,分离8 w龄子鼠大脑、海马称重,观察海马病理改变,测定全血和海马铅、锌含量,主动回避反应(AAR)测试习得率和保持率。结果:高铅组全血和海马铅浓度显著升高(P<0.01),锌浓度显著降低(P<0.01);高锌组全血和海马锌显著升高(P<0.01);高锌高铅组全血和海马铅、锌浓度无显著改变。高锌组4 w时体重增长缓慢(P<0.01),8 w时更加明显,8 w龄大脑及海马重量显著降低(P<0.01);高铅组和高锌高铅组的体重、大脑和海马重量无显著改变。高锌组电镜超微结构见部分神经元胞体较小、细胞器减少、粗面内质网扩张、核糖体脱落。其它各组光镜和电镜检查均未见明显病理改变。高铅组和高锌组AAR习得率与保持率都显著低于对照组和高锌高铅组(P<0.01)。结论:亚临床铅中毒对大鼠生长和脑发育无显著影响,但显著损害学习记忆功能,适量补锌能改善学习记忆功能。长期摄取高锌影响大鼠生长和脑发育,损害学习记忆功能。

Effects of Lead and Zinc Exposure on Growth and Development and Abilities of Learning and Memory in Young Rats

Objective: To study the effects of intrauterine and extrauterine exposure to lead and/or zinc on body growth and brain development and abilities of learning and memory in young rats.Methods: Sixteen pregnant Wistar rats were randomly divided into 4 groups: normal control group,high-lead group,high-zinc group,high-zinc & lead group.After weaning,the pups were fed the same diet as their mothers for 8 weeks.The body weights of young rats at the birth,1 week,4 weeks,8 weeks were scaled.The weights of brain and hippocampus of 8 weeks old rats were also scaled.The blood and hippocampus lead and zinc contents were measured.The pathological lesions of hippocampus were examined.Active avoidance response(AAR) was tested in one-way shuttle box.Results:(1) The blood and hippocampus lead contents of high-lead group were significantly higher and zinc contents were lower than control group.The blood and hippocampus zinc contents of high-zinc group were significantly higher than control group.The contents of zinc and lead were similar between high-zinc & lead and control group.(2) Lower body weights were only seen in high-zinc group from 4 weeks.The brain and hippocampus weights of high-zinc group were also lower than control.(3) The hippocampus ultrastructure was slightly damaged solely in high-zinc group.(4) The AAR acquisition and retention rates were approximative in control and high-zinc & lead group,both significantly higher than in high-lead and high-zinc group.Conclusion: The abilities of learning and memory of young rats with subclinical lead-poisoning are declined significantly.High-zinc diet can effectively antagonize the toxicity caused by lead.But the body growth and brain development are retarded by long-term ingestion of high-zinc diet,and the function of learning and memory are also impaired.