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Lead Exposure during Pregnancy on the Hippocampal Rats the Effects of Zinc Ion Balance

Author: SunMeiHua
Tutor: LiHaiBo
School: Jilin University
Course: Pediatrics
Keywords: lead zinc rats zinc transporter
CLC: R714.2
Type: Master's thesis
Year: 2009
Downloads: 62
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Abstract

Lead is one commom harmful metals and harm to the function of many organs and tissues of human. The nerve toxicity of lead correlate with age, the developing central nervous system is particularly sensitive to lead. It is reported that the effect of lead to high neural activities especially to children is very serious and it seems that there is no lower limit. The prenatal exposing of lead is another dangerous way to children beside environmental pollution. Lead from mother can permeate into the nervous system of fetus easily through the incomplete blood-brain barrier and cumulate in fetus especially in cortex and hippocampus, which is recognized as a key site for learning and memory.After chornic lead exposure by rodents, lead can selectively accumulate in the hippocampus region and mossy fibers caused by thinning,shortening and development of backward partial synaptic,at the same time,pyramidal cell layer changed thinner and the structure of dentate granule cell disorderd.As a trace metal body element, zine almost distribute all organs of the body. Zn2+ is mainly located in the former of the brain, particularly the distribution of the largest in the hippocampul.Hippocampus is a key part of learning and memory function. The MS to maintain the normal learning and memory function,reducing excessive glutamate release by neurotoxic damage caused by MS to maintain the pathway in the hippocampus Zn2+ content of the stability.However,if the presynaptic membrane Zn2+ over-accumulation and release of Zn2+ into the cause of excessive post-synaptic neurons,resulting in postsynaptic neuronal damage and loss.As a result of cognitive function in the hippocampus is a key brain regions,Zn2+ balance of brain function play a critical role such as learning and memory in cognitive.The hippocampal zinc balance adjustment mechanism of the complex,the latest study shows that the aggregation in the cells and transmembrane of Zn2+ is closely related to transporter family of seven members of a zinc.Hippocampal has highiy plasticity during the development. Lead exposure and neuronal axons caused by structural changes and an imbalance involved in Zn2+ renewable MF sprouting of nerve fibers can cause changes in the structure and function,both of which are involved in the cognitive impairment caused by the pathological process. It worth studying that Hippocampal zinc iron balance relation to between the exposuring of lead. so,lead exposure in children in hippocampal neurons Zn2+ is an imbalance?Vesicles in neurons is the lack of Zn2+ or excessive build-up?The existence of hippocampus MS abnormal regeneration of germination?Zinc transporter protein in which the role?With blood lead ,the relationship between brain lead?Between lead and zinc unknown what the mechanism of interaction between the inner? The study of Zn2+ in hippocampal changes in the distribution and transit may reveal low-level lead exposure, and its brain damage key node, the application of zinc is expected related to preparation for the treatment of lead poisoning leads to find a breakthrough, the discovery of new effective durg targets.This study has established a successful model of lead exposure during pregnancy.It uses atomic fluorescence determinination of rat blood and brain tissue lead content.Through the HE staining the lead exposure during pregnancy on the morphology of rat hippocampus cells .By lead exposure during pregnancy rats Timm’s staining,a clear lead exposure in rat hippocampus MS whether zinc accumulation and abnormal regenerative sprouting,as well as blood lead,the relationship between brain lead.Lead exposure during pregnancy through the hippocampus of rats in the regeneration of MS access ZnT1 the expression of lead exposure in rat hippocampus ZnT1 the changes of expression,and its relationship with blood brain and brain lead levels.Resulte:1.It set up a successful model of lead exposure during pregnancy.2.Lead exposure during pregnancy in rats,the blood lead exposure group,and brain lead levels ineresed significantly.3.Lead exposure group rats six cases of abortion,one case of dystocia,adnormal birth rate(7/15),but the normal control group without abnormal delivery.4.Pregnant rats exposuring lead in the hippocampus CA2 and CA3 areas have a large number of degenerative cells,and cells with loose cell layers reduced.5.Timm’s staining results for lead exposure group and normol group 7 days,after birth rats were 14 days of no mossy fiber sprouting,normol rats for 21 days appeared mossy fiber sprouting,and higher than the lead exposure of 21 rats days. 6.ZnT-1 in the seven days after birth lead exposure reduced the expression of rats in each group,aged rats with hippocampal cell within the intensity of ZnT-1 expression increased,lead-exposed rats for 14 days,21 days with normal control no significant difference between groups.Conclusion: The model of lead exposure during pregnancy in rat stable and reliable.Lead can enter the fetus rat placental barrier through the development of the blood-brain barrier is still not perfect to enter the fetal rat brain tissue. Lead can decrease the survival rate of hippocampal cells.It prompted embryos and early childhood lead exposure may be important in the nervous system vulnerable period to streng then the matemal and early childhood laed exposure is important to monitor the situation.A low level during pregnancy and childhood lead exposure resulted in hippocampal neurons in rats of zinc ion imbalance,while hippocampal neurons within the lower of zinc irons.It prompted neurons the zinc iron imbalance caused by lead exposure may damages the nervous system ,one of the important pathology way.

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