Text Box: PROTECTIVE EFFECTS OF ZINC ON BRAIN DEVELOPMENT IN RATS BEFORE-BIRTH AND AFTER BORNE LEAD EXPOSURE
Kong Xiangying, Yang Long, Liu Lijian
Department of Pediatrics,South West Hospital,Third Military University. Chong Qing, China

Objective: To study the protective effects of Zinc on brain development in rats of before birth and after borne lead exposure.  
Methods:  Twenty pregnant Wistar rats were randomized into 5 groups :control group(A),high lead group(B), high zinc and lead group(c),deficient zinc and high lead group(D) and deficient zinc group(E). PbAC from the 14th day after gestation. After weaning, the pups were fed likewise and weighted at 0, 1th, 4th, 8th week after birth. On the postnatal 8th week, the following procedures were manipulated in the offspring: 1. Active avoidance response (AAR)was tested in one-way shuttle box;2.The levels of lead ,Zinc in blood and hippocampus were measured; 3.The somatostatin(SOM) distribution and contration in hippocampus were determined with immunohistochemistry and imagine analysis;4.The structure of hippocampus neurons was observed with optics and electron microscopy.  
Results: 1.The body weight and weight of brain and hippocampus in B group and C group were no significantly deferent than in A group. However, in D group they were decreased than in A,B,C groups and in E group.2.The lead content in blood and hippocampus was no significantly deferent in C group than in A group ,and in B,D,E groups that was significantly higher than in A, C groups.3.In both A and C groups the AAR was approximative, and was significantly lower in B,D,E groups than in A,C groups, in D group than in B,E groups too.4.The SOM neurons in hippocampus of C group were no deferent than in A group, in B,D,E groups were significantly reduced than in A,C groups, and in D group than in B,E groups.5.The ultrastructure of hippocampus with electron microscopy in E group was significantly changed, in D group too. 
Conclusions: Under the condition of Zinc deficiency exposed to low lead can aggregate demage to central nervous system(CNS) of lead during hippocampus development. When high Zinc diet was given properly, the neurotoxicity effects were decreased in Rats of lead exposure. 
2000