The Effects Of Chronic PM_2.5 Exposure On Lung In Rats

Objective:The model of rats which were exposed to fine particulate matter?PM₂.5?chronically were established.We analyzed the effects of chronic exposure to particulate matter 2.5?PM₂.5?on mouse lung.Methods:32 SD rats were randomly divided into two groups: PM₂.5 exposure group?PM group?and filter air group?FA group?,and each group had 16 rats.8 rats of each group were sacrificed after 3 months and 6 months separately.We counted the white blood cells of bronchoalveolar lavage fluid by optical microscope,observed the pathomorphism changes of lung tissue by HE staining,detected the contents of MDA and the MnSOD activity in rats lung tissue,detected the protein expression of CD3,CD68 and hemoglobin oxide synthase?HO-1?in rats lung tissue by immunohistochemistry to observe the damage of fine particulate matter to rats lung.Results:1 The comparison of PM₂.5 concentration in each group: The statistical results showed that during 3 months?from February 1 to April 30,2015?and 6 months?from February 1 to July 31,2015?,the PM₂.5 concentration in PM group and outdoor group was significantly higher than that of FA group?P<0.05?,the PM₂.5 concentration between PM group and outdoor group had no significant difference?P>0.05?.2 The histological manifestation of lung in different groups?HE?: The results of lung histopathologic score showed that the histopathological grades of PM group were higher than that of FA group,and the pathologic scores of PM 6months group were higher than PM 3months group?P<0.05?.The changes of pathological grades between FA 3months group and FA 6months group had no statistical significance?P>0.05?.3 The comparison of WBC count and percentage of neutrophils in BALF of different groups: The results showed that WBC count and percentage of neutrophils in BALF of PM 3months group and PM 6months group were significantly increased than that of FA group?P<0.05?.WBC count and percentage of neutrophils of PM 6months group were significantly increased compared with that of PM 3months group?P<0.05?.The changes of WBC count and percentage of neutrophils in BALF between FA 3months group and FA 6months group had no statistical significance?P>0.05?.4 The Expression of CD3 of rats lung tissue in different groups:Area,IOD,IDO/Sum Area of CD3 in PM group were significantly increased compared with that of FA group?P<0.05?.Area,IOD,IDO/Sum Area of CD3 in PM 6months group were higher than that in PM 3months group?P<0.05?.The changes of Area,IOD,IDO/Sum Area of CD3 between FA 3months group and FA 6months group had no statistical significance?P>0.05?.5 The Expression of CD68 of rats lung tissue in different groups: Area,IOD,IDO/Sum Area of CD68 in PM group were significantly increased compared with that of FA group?P<0.05?.Area,IOD,IDO/Sum Area of CD68 in PM 6months group were higher than that in PM 3months group?P<0.05?.The changes of Area,IOD,IDO/Sum Area of CD68 between FA 3months group and FA 6months group had no statistical significance?P>0.05?.6 The comparison of MDA contents in lungs of rats in different groups: The results showed that the MDA contents of PM group were significantly higher than that of FA group?P<0.05?.The MDA contents of PM 6months group were significantly higher than that of PM 3months group?P<0.05?.The changes of MDA contents between FA 3months group and FA 6months group had no statistical significance?P>0.05?.7 Mn SOD activity in lungs of rats in different groups: The results showed that the MnSOD activity of PM group were significantly lower than that of FA group?P<0.05?.The MnSOD activity of PM 6months group were significantly lower than that of PM 3months group?P<0.05?.The changes between FA 3months group and FA 6months group had no statistical significance?P>0.05?.8 The comparison of the Expression of HO-1 in different groups: Statistical results showed that Area,IOD,IDO/Sum Area of HO-1 in PM group were significantly increased compared with that of FA group?P<0.05?.Area,IOD,IDO/Sum Area of HO-1 in PM 3months group were higher than that in PM 6months group?P<0.05?.The changes of Area,IOD,IDO/Sum Area of HO-1 between FA 3months group and FA 6months group had no statistical significance?P>0.05?.Conclusion:1 This study established a model of rats in which the animals were exposed to fine particulate matter?PM₂.5?chronically.2 Chronic PM₂.5 exposure could lead to inflammatory response in lung of rats,and the longer the exposure time,the more severe the inflammation.3 Chronic PM₂.5 exposure could lead to oxidative stress injury in lung of rats.And along with the extension of exposure time,the damage became heavier.4 Chronic PM₂.5 exposure could lead to inflammatory response in lung of rats by oxidative stress injury.