Impact of chronic low-level lead exposure on neuronal growth associated protein expression of hippocampus and learning-memory in rats

Objective To explore the effect of chronic low-level lead exposure at developmental stages on learning-memory and the expression of neuronal growth associated protein 43(GAP-43) in hippocampus in rats.Methods Thirty pregnant rats were randomly divided into 3 groups and provided with distilled water in control group and 0.05%,0.2% lead acetate solution via drinking water in treatment groups.During pre-weaning the offspring of lead-exposed group drank lead acetate through breast milk,and they continued to drink the same concentration of lead acetate after weaning until 28th day after the birth(PN28).Morris water maze was applied to observe the special learning and memory of the rats of PN28.Western blot technique was applied to detect the change of expression of GAP-43 in hippocampus.Results The scores of Morris water maze task were significantly reduced in Pb-exposed groups compared with that of the control group(P 0.05).In the hippocampus,the protein expression in Pb-exposed group(0.05%PbAc:0.258±0.089,0.832±0.021,0.806±0.047,0.933±0.010,0.593±0.004,0.437±0.015;0.2%PbAc:0.115±0.010,0.590±0.018,0.680±0.027,0.703±0.004,0.450±0.014,0.325±0.007) exhibited a significant decline at the time of 1,3,7,14,21,and 28 days after the birth compared to those of the control group(P0.05 for all).Conclusion Chronic lead exposure results in decrease of special learning and memory and its effect may related to the decline of expression of GAP-43 in hippocampus.