| Objective: To investigate the effect of lung injury related factors on the transcription level of?2 receptor in SD rats after severe traumatic brain injury(STBI).Methods: Twenty-four male SD rats were randomly divided into normal group(n =6)and STBI group(n =18);the STBI rat model was made according to the method described by Feeney et al.Six rats in STBI group were killed at 1,2 and 7d after injury for observation.After HE staining,the morphological changes of lung tissue were observed by light microscopy.Pathological scoring of lung tissue was evaluated by the method described by Han Bingchao et al.The content of TNF-? and IL-6 in bronchoalveolar lavage fluid(BALF)was detected by ELISA,and the transcription level of ?2 receptor was detected by quantitative PCR.Results: Pathological changes such as pulmonary capillary congestion,inflammatory cell exudation,and pulmonary interstitial thickening could be observed at each phase in rats of the STBI group under light microscopy.According to the pulmonary interstitium,alveolar edema,inflammatory cell infiltration,alveolar hemorrhage,hyaline membrane formation and atelectasis changes,its degree of none,light,medium and heavy set to 0,1,2 and 3 points respectively,and then accumulated total score: normal group:1.67±0.52,the first day after STBI group :3.67±0.82,the second day after STBI group:6.17±1.17,the seventh day after STBI group:9.67±1.37;there was statistically significant difference in lung histopathology scores between the groups(F=68.520,p < 0.01).Compared with each other at different time points,the pathological score of lung tissue increased progressively(p < 0.05)and reached the highest level on the 7th day after STBI(p < 0.05).Transcription level of ?2 receptor in rats lung: normal group: the first day after STBI group : 0.078±0.021,the second day after STBI group: 0.18±0.52,the seventh after STBI group:0.62±0.11;The transcription level of ?2 receptor was significantly lower than that of normal group at all time points(p < 0.05),and reached the lowest value at 1d(p < 0.05);the content of TNF-? in BALF of rats lung : normal group: 3.64±0.81pg/ml,the first day after STBI group : 28.34±1.78pg/ml,the second day after STBI group: 17.11±2.09pg/ml,the seventh day after STBI group:11.28±2.33pg/ml;the content of TNF-? in BALF of rats lung was significantly higher than that in normal group at all time points(p < 0.05),and reached the peak value at 1d(p < 0.05);the content of IL-6 in BALF of rats lung:normal group:72.81±7.70pg/ml,the first day after STBI group: 101.16±10.59pg/ml,the second day after STBI group: 146.33±8.17pg/ml,the seventh day after STBI group:94.15±6.36pg/ml;the content of TNF-? in BALF of rats lung was significantly higher than that in normal group at all time points(p < 0.05),and reached the peak value at 2d(p <0.05).Correlation analysis showed that the content of TNF-? in BALF of rats lung was negatively correlated with ? 2 receptor transcription levels at 1d,2d and 7d(p=0.039,0.032,0.033,r =-0.834,-0.850,-0.848).The content of IL-6 in BALF of rats lung was negatively correlated with ? 2 receptor transcription levels at 1d,2d and 7d(p=0.023,0.045,0.016 r=-0.874,-0.821,-0.894).Conclusion: Rats have the performance of acute lung injury after STBI,and the degree of injury progressively aggravated with the extension of time.Inflammatory factors,TNF-?and IL-6,are able to induce acute lung injury in rats after STBI by activating systemic inflammatory effector cells;meanwhile,increased TNF-? and IL-6 inhibited the transcription of ?2 receptor gene,which leads to the decline of ?2 receptor density in lung tissue,and may also be related to the occurrence of acute lung injury in rats after STBI. |
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