甲基汞暴露对仔鼠学习记忆能力的影响

Effects of exposuse to methymmercury on learning and memory in young rats

目的评价出生前后甲基汞暴露对仔鼠学习记忆能力的影响。方法将SD孕鼠分3组:对照组、低剂量组、中剂量组,后两组孕鼠自孕7d至哺乳期分别予以0. 1mg.kg-1.d-1和1mg.kg-1.d-1剂量的甲基汞暴露,Morris水迷宫对3组仔鼠学习获得和记忆保持能力进行测试和分析。结果Morris水迷宫学习获得试验测试结果表明:对照组定位能力较好,游泳轨迹以目标象限为主;而汞暴露组定位能力较差,游泳轨迹比较分散。汞暴露游速比对照组快,潜伏期长,其游程也更长,各组间呈现剂量效应关系(P<0. 05)。对照组、低剂量组、中剂量组的潜伏期(s)分别为24. 21±2. 13, 48. 55±3. 78, 55. 04±4. 15;目标象限游程占总游程百分比分别为34. 73±1. 42, 26. 104±1. 29, 28. 65±1. 21;总游程(cm)分别为576. 51±57. 94, 1 387. 90±112. 57, 1 584. 38±121. 55。记忆保持实验测试中的各项指标3组差异不明显。结论母鼠孕期及哺乳期甲基汞暴露可影响仔鼠学习、记忆能力,并以近期学习获得能力的损害为主,呈剂量效应关系。

ObjectiveTo evaluate the effects of prenatal and postnatal exposure to methylmercury on learning and memory in young rats. MethodsDivided the pregnant SD rats into three groups: the control, low-level, and middle-level one. After exposing the rats of latter two groups from 7 days in pregnancy through lactation with methylmercury(the dose were 0.1mg.kg^(-1).d^(-1 )and 1mg.kg^(-1).d^(-1) respectively), tested the offspring's ability in the trials of place navigation and retention place navigation with Morris water maze. ResultsIn the trials of place navigation, the rats in the control group showed better orientation ability, and their swim traces were mainly limited in the target quadrant; while the methylmercury exposed groups' orientation ability was poor, and their swim traces were distracted. The rats in the exposed group swam faster than the ones in the control group, and the formers spent more time in finding the latent platform and swam longer distance, and the relationship among the three groups was presented in dose-effect (P<0.05). The mean values of the control group, low exposure group and middle exposure group are 24.21±2.13,48.55±3.78,55.04±4.15 separately in the latency to find the platform(s); 34.73±1.42,26.104±1.29(cm/s),28.65±1.21 separately in target quadrant(percent of time)and 576.51±57.94,1387.90±112.57,1584.38±121.55 separately in the cumulative distance(cm). During the trials of retention place navigation the differences in the three groups were not apparent. ConclusionThe exposure of methylmercury to rats in pregnancy and lactation resulted in the impairment of learning and memory in their offspring, especially in short-term learning acquisition, and the effects were presented in dose-effect relationship.