| Purpose: To observe the protective effect of morphine on lung against intestinal ischemia / reperfusion in rats , and to investigate the underlying mechanism, and to provide new experimental evidence for the expansion of its clinical use.Methods: 32 male wistar rats, weighing 250～300g , Were randomly divided into 4 groups of (n=8/group).sham operation group (group S), ischemia-reperfusion group (group I/R), morphine group (group M), naloxone group (group N). The I/R model was established by clamping superior mesenteric artery (SMA)for 1 hour and reperfusing for 2 hours. morphine was administered (300ug/kg body weight,IP) at 15 minutes before ischemia in Group M.In the group N, naloxone was administered(3mg/kg body weight,IP) at 10 minutes before administered morphine ,the other are same with group M .In the sham group, SMA was only isolated without clamping.Blood sample and lung tissue samples were collected after reperfusion 2 hours.The blood sample was collected for the content of TNF-α; The right lobus superior pulmonis were removed for Pathology of transmission electron microscope,and the right lobus medius pulmonis for lung water content,and then lobus inferior pulmonis for Pathology of light microscope and the expression of NF-κB,ICAM-I.Results:1 The content of TNF-αin plasmaCompared With the group S, the content of TNF-αin plasma was increased significantly in group I/R,M and N (P <0.05); Compared with the group I/R, the content of TNF-αwas lower in group M(P <0.05) ,while there was not significant different between group N and I/R (P >0.05).2 Pathology of transmission electron microscopeGroup S: The cell organelles, mitochondria of lung were normal, the typeⅡcells were integrated,and the basement membrane of air-blood barrier was very clear;Group I/R: There were a large number of red blood cells,cytoplasm and epithelial shedding nucleus in alveolar space.The lamellar body and microvillus of type II cell decreased significantly. A large number of collagen fibers hyperplasiaed,pulmonary closure was existed onpartial lung.Group M : The basement membrane of air-blood barrier was integrated,but there was a little became thicker and more uneven; Type II cells were normal. Mitochondria had mild damaged;Group N : The pathological changes of lung was more serious than group M.3 Lung water contentCompared With the group S, the content of water in lung was increased significantly in group I/R and N (P <0.05),but the data did not appared statistical difference between group M and S; Compared with the group I/R, the content of water was lower in group M(P <0.05) ,while there was not significant different between group N and I/R (P >0.05).4 Pathology of light microscopeGroup S: The structure of pulmonary alveoli were clear, there was a little of PMN infiltrated in pulmonary stroma,alveolar space did not hemorrhage ;Group I/R: Alveolar wall became thicker, alveolar expanded non-uniformly,pulmonary stroma and alveolar space had a lot of PMN infiltrated, alveolar had hemorrhage;Group M: The pathological changes of lung was lighter than group I/R ,and the structure of pulmonary alveoli was much clearer than group I/R.Group N: The pathological changes of lung was more serious than group M.5 The expression of NF-κB in lung tissue The grade of HIS:Compared With the group S, The grade of HIS was increased significantly in group I/R and N (P <0.05),but the data did not appared statistical difference between group M and S(P >0.05); Compared with the group I/R, the grade of HIS was lower in group M(P <0.05) ,while there was not significant different between group N and I/R (P >0.05). 6 The expression of ICAM-I in lung tissueThe grade of HIS:Compared With the group S, The grade of HIS was increased significantly in group I/R and N (P <0.05),but the data did not appared statistical difference between group M and S(P >0.05); Compared with the group I/R, the grade of HIS was lower in group M(P <0.05) ,while there was not significant different between group N and I/R (P >0.05).Conclusion:morphine can protect lung against IIR injury, which may be associated with inhibiting the activition of NF-κB then reduce the expressions of TNF-αand ICAM-I, and all of which were related with opioid receptor.
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