Study On The Epigenetic Change Of Central Nervous System Caused By Early Traffic Pollution Exposure

Objective:Investigate the epigenetic change of central nervous system caused by traffic pollution before and after birth.Methods:Wistar rats were employed in this experiment.Pregnant female rats?recorded as group E?and new born rats?recorded as group P?were exposed to different places with three levels of traffic pollution.Body weight,length and brain coefficient of the offspring were measured from the 21^st to 27^th day after the birth.Social behavior was assessed using three chambers test.The methylation level of LINE-1,the oxytocin receptor gene?OXTR?and the histone3 lysine4?H3K4?which represented the methylation level of brain were analyzed.The differences and characteristics of epigenetic changes in brain tissue before and after birth caused by traffic pollution were compared.The relationship between various epigenetic changes,social behavior abnormalities and epigenetic changes in the central nervous system were analyzed.Results:The concentration of NOx was statistically different,but the concentration of PM_2.5 was not.Growth and development indicators showed that exposure to traffic pollution during embryonic period had an effect on body weight,body length and brain organ coefficient?P<0.001?,but had no effect on BMI?P>0.05?.The indicators had no difference for new born Wistar rats.Neurobehavioral results showed that traffic pollution had an impact on the rats'social ability if they were exposed to the pollution during embryonic period.Furthermore,high concentration of traffic pollution would cause damage to social memory and social novelty.The epigenetic results showed that the average methylation level of LINE-1 gene decreased significantly(P_EM<0.05,P_EH<0.001)and the average methylation level of OXTR gene increased(P_EH<0.001)in high concentration pollution in embryonic period.But no significant change was observed in the postnatal exposure group.Traffic pollution exposure before or after birth did not significantly change the total methylation level of H3K4me3 and H3K4.There was a positive correlation between the average methylation rate of LINE-1 gene and the total methylation rate of H3K4 in the postnatal group?r=0.265,P=0.041?.Conclusion:Exposure to traffic pollutants before and after birth have adverse effects on social behavior of young rats.Sensitivity to the traffic pollutants is different during the growth.It is shown that the exposure to traffic pollution in embryonic period cause the decrease of LINE-1 gene methylation and the increase of OXTR gene methylation of central nervous system.Results indicate that the early exposure to traffic pollution is relevant to autism and other central nervous system diseases through epigenetic changes.