Abstract: Abstract:Objective To investigate the hippocamal neuron injury   in pup rats caused by lead exposure  from pregnancy to juvenile stage and the mechanism related to zinc balance. Methods Twenty-five female Wistar rats were randomly divided into control group (n=10) and lead exposure group (n=15).The pup rats of each group were subdivided into three subgroups depending on different observation periods from pregnancy to postnatal 7,14,and 21 d (P7,P14 and P21 subgroups),respectively; each subgroup was composed of 8 pup rats.The female rats in  lead exposure  group were bred with 0.2% lead acetate in drinking water from pregnancy to P7,P14,and P21 of the pup rats,respectively,while the mothers in control group drank water consistently.The  blood and brain lead contents were detected on P7,P14,and  P21 of the pup rats in each subgroup.Timm’s staining was used to observe the mossy fiber (MF) in hippocamspus,and immunohistochemistry assay was performed to detect the expression levels of  zinc transporter 1 (ZnT-1).Results The blood and brain lead contents  in lead exposure subgroups were significantly higher than those in  corresponding control subgroups(P<0.01).There were mass of degenerated cells  in CA2 and CA3 regions of  hippocampus in pup rats after lead exposure,and the nerve cell arrangement was unconsolidated,and the number of cell layers was decreased.The Timm’s staining results showed that MF  sprouting presented on P21 of the pups in control group,and the absorbtion(A) value was 0.135 0±0.024 3.The A valueof P21 in lead exposure  group was 0.096 7±0.024 2,which was significantly lower than that in  control group (P<0.01).The expression of ZnT-1 was significantly decreased on  P7 of the pups in lead exposure  group compared with  control  group (P<0.01).There was no significant difference of ZnT-1 expression on P14 and P21 between lead exposure and control group.Conclusion There may exist neuronal zinc imbalance in pup rats after low-level lead exposure  from pregnancy to juvenile stage,and it may cause the decrease of the intracellular Zn2+level in hippocampal neurons after lead exposure.

Key words:  , lead, zinc, pup rat, zinc transporter