Study On The Impact And Mechanism Of Developmental Hippocampal Neuronal Development Induced By Food-derived Pb Exposure

Food safety and human health are closely related,and with the environmental problems prominent,food-derived Pb exposure is not uncommon.Pb,as a traditional heavy-metal pollutant,can make poisonous harm to nervous system,especially central nervous system.And environment pollution can gather Pb in foods.The data from early-days research tells us,Pb can harm the rats' recognition ability in their developmental period,but the internal mechanisms are entirely unsure.Recently,some studies indicate Pb-exposure may cause the inhibition of neuronal development,but researches on its internal regulating mechanisms are lacking.Objective: Researching on the effects produced by Pb-exposure to Sprague-Dawley(SD)rats' hippocampal neural proliferation and differentiation as well as some relevant signal paths;researching on particular biological molecular mechanisms how Pb-exposure regulates the neural mature process,further speculating the possible mechanism in neurodegenerative diseases response to Pb-exposure.Methods:1.SD rats,including 1/4 males and 3/4 females,are syncopated into two groups,one is called Control group(Ctrl)and the other is chronic Pb-exposure group(PEG).The Ctrl is fed distilled water,the PEG is fed Pb water which consists of 250 ppm lead acetate and distilled water.The rats are exposed by Pb since their embryonic period.Before they are weaned,they are exposed by Pb when they are fed breast milk.After weaning,they are exposed by Pb directly by fedding distilled water.Workers intraperitoneal inject BrdU into the two groups of rats' once a day when they are 19-21 days old.Then on the next day workers should kill them.Immunohistochemistry observe the number of new-born neurons in hippocampal district.Western blot test the number of related protein in classical Wnt signal pathway.Q-PCR observes how mRNA expression in classical Wnt signal pathway.2.Taking hippocampal neurons in vitro culture as experimental material,workers investigate how Pb-exposure causes the inhibition of neuronal development from the regulation of RNA.Taking new-born rats' hippocampal issues in cell culturing,and on the third day workers add 5?M lead acetate in culturing dishes,then expose them for 11 days,finally take them back on the 14 th day.Western blot test and q-PCR test observe the expression of Kmt2a(MLL1)from the perspectives of protein and RNA,and q-PCR observes how LncRNA expression.Results:1.Pb-exposure obviously reduces the number of new-born neurons in rats' hippocampal areas.2.Pb-exposure obviously improves the effect how P-?-catenin protein,and reduce the effect how P-GSK-3? protein.3.Pb-exposure obviously suppress the expression of MLL1 protein,and reduce the expression of mRNA.4.Pb-exposure regulates the distribution of H3K4me3 on the chromatin by LncRNA.Conclusion: This study approves that Pb-exposure can refrain the development of neurons in brain from two aspects,such as classical Wnt signal pathway and target molecule H3K4me3.1.Pb-exposure may affect the proliferation and differentiation of new-born neurons in rats' hippocampal areas during their developmental period by blocking the Wnt signal pathway.2.Pb-exposure can make difference on the expression of MLL1 which regulates the maturation of neurons,and changes the distribution of H3K4me3 on the chromatin by regulating LncRNA.This result offers us a new point about researching on the effects taking by Pb-exposure to neurotoxicity.