锌铅对大鼠子代生长发育和学习记忆的影响

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

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。

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 hippocarnpus 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.