Research On The Effect Of Aerobic Interval Exercise In Improving The Respiratory System Injury In Rats Caused By Acute Particulate Matter Exposure

Objective:With the increasingly serious air pollution in recent years,a series of damage caused by atmospheric particles to human body has been confirmed by a large number of studies.In particular,acute inhalation of PM_2.5.5 caused serious damage to the respiratory system.In contrast,many other studies have shown that regular aerobic exercise can effectively improve the respiratory system function.When the severe pollution weather comes,in the extreme particle pollution weather,people with daily exercise habits and people without exercise habits have different body tolerance,and the protective effect of exercise is not the same.Through the intervention of aerobic intermittent exercise and the successive effects of short-term and different concentrations of PM_2.5 exposure,we observed the difference improvement effect of pre exercise on the damage of vital organs（lungs）of respiratory system caused by different concentrations of PM_2.5 acute exposure,and explored whether the protective effect of long-term regular aerobic exercise can resist particles The body damage and its related mechanism caused by sports can provide theoretical basis and experimental support for sports intervention to resist the pulmonary toxicity of particles,and have certain guiding significance for the development of national fitness.Methods:seven week old Wistar rats were randomly divided into 8 groups:sedentary control group（S）,exercise training group（E）,sedentary+low concentration PM_2.5 exposure group（S+LPM）,sedentary+medium concentration PM_2.5 exposure group（S+LPM）Exposures,S+MPM,sedentary+high concentration PM_2.5 exposures,S+HPM,exercise+low concentration PM_2.5exposures,E+LPM,exercise+medium concentration PM_2.5 exposures Exposure,E+MPM),exercise+high concentration PM_2.5 exposure（E+HPM）.Among them,the exercise intervention group（E,E+LPM,E+MPM,E+HPM group）had 8 weeks of aerobic intermittent exercise intervention.After the exercise plan was completed,all groups except Group s and E were exposed for 6 hours.The dose of PM_2.5 in low concentration group（S+LPM,E+LPM group）was about149±30.88μg/m³,that in medium concentration group（S+MPM,E+MPM group）was about269.31±30.79μg/m³,and that in high concentration group（S+HPM,E+HPM group）was about 509.84±36.74μg/m³.After the exposure,the lung function was detected by in vivo and noninvasive whole-body plethysmography detection system;after he staining,the morphological changes of lung tissue were observed under light microscope;the contents of IL-1β,TNF-α,arachidonic acid pathway related protein COX-2 and PGE2 in lung tissue were detected by ELISA and immunoblotting,respectively.Results spss20.0 system analysis software was used for preliminary statistical analysis,and then the effect value of each research factor was further tested by calculating the effect value.Results:（1）in terms of lung function,compared with the control group（S group）,the respiratory frequency and ventilation volume per minute of each particle exposure group（S+LPM,S+MPM,S+HPM group）were significantly reduced,while the indexes of inspiratory time and expiratory time were all increased;interestingly,compared with the control group（S group）,the indexes of maximum respiratory velocity in S+MPM group were significantly reduced（P<0.05,ES=1.27,higher）But E+HPM group was significantly higher than E+LPM group（P<0.05,ES=1.03,higher effect）.（2）In the aspect of lung histomorphology,the lung tissue of group S and group E was normal as a whole,with clear structure,continuous and complete alveoli,complete bronchioles and terminal bronchioles,without sclerosing.Pulmonary artery endothelial integrity,smooth muscle layer clear,no inflammatory infiltration around.In the S+LPM group,there was slight bleeding and inflammatory cell infiltration in the local tissues;macrophages,neutrophils and plasma cells were scattered in the alveoli,and a small amount of pus exuded and filled.Compared with the S+LPM group,the pulmonary hemorrhage was more serious in the S+MPM group.The inflammatory cells were scattered in the alveolus cavity,the bronchial mucosa was damaged continuously and some of them fell off,and the inflammatory cells were gathered in the peripheral of pulmonary artery and bronchus.In the S+HPM group,a large number of alveoli were filled and blocked by purulent blood and inflammatory cells,and the inflammatory cells around the blood vessels and bronchi gathered into massive masses,accompanied by a large number of bronchial mucosa swelling,necrosis and shedding.Compared with the quiet control group（S+LPM group）,the lung tissue of E+LPM group was only slightly bleeding and inflammatory infiltration,and the alveolar structure was clear and complete;the overall situation of lung tissue of E+MPM group was better than that of E+MPM group,and the degree of bleeding and inflammatory infiltration was significantly improved.In the E+HPM group,there were pus,inflammatory cells,plasma cells and macrophages in the alveoli,but local hemorrhage and inflammatory infiltration were significantly reduced.（3）In the aspect of inflammatory factors:in the change of TNF-αconcentration,S+MPM group（P<0.05,ES=1.28,higher effect quantity）and S+HPM group（P<0.05,ES=1.55,higher effect quantity）were significantly higher than s group;E+MPM group was significantly lower than S+HPM group（P<0.05,ES=1.01,higher effect quantity）,while E+HPM group was also significantly lower than S+HPM group（P<0.05,ES=1.28,higher effect quantity）Effect quantity).In the change of IL-1βconcentration,compared with s group,S+MPM group（P<0.05,ES=0.92,higher effect quantity）and S+HPM group（P<0.05,ES=1.28,higher effect quantity）were significantly higher;E+MPM group was significantly lower than S+MPM group（P<0.05,ES=0.74,medium effect quantity）,in addition,E+HPM group was also significantly lower than S+HPM group（P<0.05,ES=1.06,higher effect quantity）)（4）In the aspect of pathway protein,S+MPM group was significantly lower than S group（P<0.05,ES=0.08,low effect quantity）;E+MPM group was significantly higher than S+MPM group（P<0.05,ES=2.75,high effect quantity）;in addition,E+HPM group was also significantly higher than S+HPM group（P>0.05,ES=1.25,high effect quantity）.Conclusion:（1）Pre exercise intervention can improve PM_2.5-induced lung function decline and lung tissue morphology change in rats.The effects of high concentration exposure and exercise are more significant.（2）Pre exercise intervention can reduce the increase of inflammatory factors in lung tissue of rats caused by PM_2.5,and the inflammation is more obvious in high concentration exposure and the decrease of inflammatory factors is more significant after exercise.（3）Pre exercise intervention can improve the anti-inflammatory effect of PGE2 itself when PM_2.5 invades the body.After exercise,the anti-inflammatory effect of PGE2 exposed to high and medium concentrations is more obvious.