| Objective:We developed a rat model in which the rats were long-time exposed to PM2.5,followed by intervention with N-acetylcysteine.We investigated inflammatory responses and oxidative stress in a rat model of chronic exposure,and analyzed the effect of N-acetylcysteine on it.Methods:24 male SD rats?220±20g?were randomly divided into 3 groups?n=8?: PM2.5 exposure group?PM group?;PM2.5+N-acetylcysteine?PM+NAC group?;Filtered air group?FA group?.PM group and PM+NAC group exposured in a 10 square meters room in Shijiazhuang city,Hebei province,the room keep window open,maintain good indoor ventilation,maintain indoor and outdoor PM2.5 concentrations similar;we respectively give physiological saline1ml/1Kg·d and NAC mixed suspension 150mg/Kg·d intragastric administration.FA group: the rats were placed in the room of 10 square meters,keeping doors and windows closed,indoor air filters remain open,rats inhalation clean air,physiological saline 1ml/Kg·d intragastric administra tion.The each group rats were sacrificed after 180 days.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 From February 1,2015 to July 31,2015,PM2.5 concentration?median and interquartile range?in outdoor?Outdoor?,indoor?PMgroup?and air purifiers indoor?FAgroup?were:[60.00?80.40?] mg/m3;[60.65?79.53?] mg/m3;[17.70?15.67?] mg/m3,the PM2.5 concentration in PMgroup and Outdoor was significantly higher than that of FAgroup?P < 0.05?,the PM2.5 concentration between PMgroup and outdoor had no significant difference?P > 0.05?.2 The histological manifestation of lung in different groups?HE?: Pathology of lung tissue inflammation score of PM group was significantly higher than that of FA group and PM+NAC group?P < 0.05?,lung tissue inflammation score of PM+NAC group was higher than that of FA group?P < 0.05?.3 The comparison of WBC count and percentage of neutrophils in BALF of different groups: white blood cell counts in BALF of PM group,FA group,PM+NAC group were?28.69 ± 6.44?×106/L;?928 ± 2.83?×106/L;?17.53± 5.07?×106/L respectively;neutrophils cell counts were?17.50±3.72?×106/L;?2.10±0.96?×106/L;?7.13±2.83?×106/L respectively;percentage of neutrophils were?62.19±11.66?%,?22.18±7.97?%,?40.56± 10.31?respectively.The WBC count and percentage of neutrophils in BALF of in group PM was significantly higher than that in group FA and group PM+NAC,while WBC count and percentage of neutrophils in BALF of the PM+NAC group was significantly higher than that in FA group.4 The Expression of CD3 and CD68 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 and PM+NAC group?P < 0.05?.Area,IOD,IDO/Sum Area of CD68 in PM group were significantly increased compared with that of FA group and PM+NAC group?P < 0.05?.5 The comparison of the Expression of HO-1 in different groups: the Area,IOD,IOD/Sum area of HO-1 in PM group were higher than that of PM +NAC group and FA group,and the Area,IOD,IOD/Sum area of HO-1 in PM +NAC group was higher than that in FA group?P < 0.05?.6 The comparison of MnSOD activity in lungs of rats in different groups: the activity of MnSOD in PM group,FA group,PM+NAC group were:?66.50 ±10.58?obtained U/mgpro;?103.25 ±12.54?obtained U/mgpro;?89.39 ± 1.63?obtained U/mgpro respectively.The MnSOD activity in PM group were significantly lower than that in FA group and PM+NAC group?P < 0.05?.The MnSOD activity in PM+NAC group were significantly lower than that in FA group?P < 0.05?.7 The comparison of MDA contents in lungs of rats in different groups: The content of MDA in PM group,FA group,PM+NAC group were:?1.77 ± 0.12?mmol/gpro;?1.03 ± 0.10?mmol/gpro;?1.34 ± 0.09?mmol/gpro respectively.The content of MDA in PM group was higher than that in FA group and PM+NAC group?P < 0.05?,and the content of MDA in PM+NAC group were higher than that in FA group?P < 0.05?.Conclusion:1 Chronic PM2.5 exposure could induce lung inflammatory responses by oxidative stress.2 N-acetylcysteine could decrease inflammatory responses in lung by suppressing oxidative stress. |
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