Effects of zinc on learning memory and expression of BDNF in lead exposed mice

Objective To investigate the protective effect of zinc in the lead exposed mice through observing the blood and hippocampal lead and zinc levels,hippocampal BDNF mRNA expression,and the spatial learning memory performance.Methods The 60 mice were equally divided into five groups,i.e.the control group,lead exposed group,low dose zinc intervention group,medium dose zinc intervention group,and high dose zinc intervention group.Under the same feeding condition,the mice were provided with distilled water,1.0 g/L lead acetate,0.2 g/L zinc acetate+1.0 g/L lead acetate,0.4 g/L zinc acetate+1.0 g/L lead acetate,and 0.6 g/L zinc acetate+1.0 g/L lead acetate.Morris water maze(MWM)test was employed for evaluating the spatial learning memory ability in the mice.After eight weeks,the levels of lead and zinc in blood and hippocampus,and the hippocampal BDNF mRNA expression were determined.Results The escape latency increased in lead and low dose groups(P0.01),while the moderate and high doses groups showed shorter escape latency than those of the lead group and low dose group(P0.01).Compared to the control,the difference was not statistically significant(P0.05).The expression level of hippocampal BDNF mRNA in lead exposed group was the lowest and in the control group was the highest,and also the expression was positively correlated with the doses of zinc intervention.The expression levels of hippocampal BDNF mRNA in various zinc doses intervention groups were higher than that of the lead exposed group(P0.01).Conclusions Zinc supplement in certain amount could partially antagonize the elevation of lead and lowering of zinc in blood and hippocampal induced by lead exposure.Elevation of the expression level in hippocampal BDNF mRNA may mitigate the learning memory injury induced by lead exposure.