亚慢性锰暴露致大鼠学习记忆能力持续性损害

Sub-chronic manganese exposure leads to persistent damage of learning and memory ability in rats

目的研究亚慢性锰暴露停止后,锰所致大鼠学习记忆能力损害的持续性情况。方法将无特定病原体级刚断乳雄性SD大鼠随机分为对照组和低、中、高剂量组,每组6只;分别予0、5、10、20 mg/kg体质量氯化锰溶液腹腔注射,每周暴露5 d,连续6周后停止锰暴露,继续观察12周。实验期间,称量大鼠体质量。于锰暴露第6周(即停止锰暴露第0周)和停止锰暴露第6、12周,采用Morris水迷宫实验检测大鼠学习记忆能力。停止锰暴露后12周处死大鼠,检测心脏、肝脏、脾脏、肾脏和睾丸脏器系数。结果锰暴露第4、6周和停止锰暴露后第2周,高剂量组大鼠体质量均低于其余3组(P<0.05);停止锰暴露后第12周,各组大鼠体质量比较,差异无统计学意义(P>0.05)。停止锰暴露后,高剂量组大鼠逃避潜伏期长于对照组(P<0.05),低、中、高剂量组大鼠穿越平台次数均少于对照组(P<0.05)。与锰暴露第6周比较,停止锰暴露后第6和12周大鼠逃避潜伏期均缩短,穿越平台次数均增加(P<0.05)。停止锰暴露后第12周,4组大鼠心脏、肝脏、脾脏、肾脏和睾丸脏器系数分别比较,差异均无统计学意义(P>0.05)。结论亚慢性锰暴露可损害大鼠学习记忆能力;停止锰暴露后,锰所致大鼠学习记忆能力的损害仍可持续存在。

Objective To investigate the persistent damage of learning and memory ability after the cessation of sub-chronic manganese(Mn)-exposure in rats.Methods Specific pathogen free weaning male SD rats were randomly divided into control group and low-,medium-and high-dose groups based on body weight,with 6 rats in each group.Rats were intraperitoneally injected with Mn chloride(MnCl2·4 H2O)at the concentrations of 0,5,10,or 20 mg/kg body weight,5 days per week for 6 weeks and continued to be observed for 12 weeks after the cessation of Mn-exposure.During the experiment,the body mass of the rats was weighed.Learning and memory ability was evaluated by a Morris water-maze task at the 6 th weeks of Mn-exposure(cessation of Mn-exposure of week 0),the 6 th and 12 th week of the cessation of Mn-exposure.The organ coefficients of heart,liver,spleen,kidney and testicles were evaluated after the cessation of Mn-exposure on week 12.Results The body mass of the high-dose group was lower than that of the other 3 groups(P<0.05)at the 4 th and 6 th week of Mn-exposure and the 2 nd week of the cessation of Mn-exposure.There was no significant difference in body mass between the groups(P>0.05)on the 12 th week of the cessation of Mn-exposure.The escape latency of high-dose group was higher than that of the control group(P<0.05),and the number of platform crossings in the low-,medium-and high-dose groups were fewer than that in the control group(P<0.05)after the cessation of Mn-exposure.The escape latency was shorter and the numbers of platform crossings were higher on the 6 th and 12 th week of the cessation of Mn-exposure(P<0.05)when compared with that of the 6 th week of Mn-exposure rats.There was no statistical significance in the organ coefficients of heart,liver,spleen,kidney and testicles among the 4 groups at the 12 th week of the cessation of Mn-exposure in rats(P>0.05).Conclusion Sub-chronic Mn exposure can impair learning and memory ability of rats,and the damage persists after the cessation of Mn-exposure.