| Objective:To investigate the protective effect and mechanism of sevoflurane pretreatment on lung injury induced by distal limb ischemia reperfusion（IR）in rats.Methods:Twenty-eight adult healthy male SD rats were selected and divided into 4 groups according to the random number table method,with 7 rats in each group.Sham operation group（Sham group）: only the bilateral femoral arteries and veins of rats were isolated without clipping,and exposed for 5 hours;distal limb ischemia-reperfusion group（IR group）: the bilateral femoral arteries of rats were clipped for 3 hours,the distal limb ischemia-reperfusion model was established by the method of reperfusion for 2 hours;the sevoflurane pretreatment + distal limb ischemia-reperfusion group（S-IR group）: the rats were pre-inhaled with 2.5%sevoflurane for 30 minutes,and then the Lower extremity ischemia-reperfusion model;sevoflurane preconditioning sham operation group（SS group）: rats were pre-inhaled with 2.5% sevoflurane for 30 minutes,and the same operation was performed as the Sham group.After the experiment,the blood and lung tissue of each group of rats were collected,and the rats were sacrificed under anesthesia.Observation indicators:（1）Determine the wet/dry weight ratio（W/D）and total lung water content（TLW）of the lung tissue of the rats in each group;（2）Observe the pathological changes（HE）of the lung tissue of the rats in each group under an optical microscope.（3）Enzyme linked immunosorbent assay（ELISA）was used to detect the contents of oxidative stress factors lipid oxidation（MDA）and superoxide dismutase（SOD）in lung tissue and serum of rats in each group to reflect the degree of oxidative stress injury.The levels of inflammatory factors TNF-α,IL-1β and IL-6 in lung tissue and serum of rats in each group were also detected by enzyme-linked immunosorbent assay（ELISA）,so as to show the content of inflammatory mediators in each group;（4）The protein expression levels of p38 mitogen-activated protein kinase（p38）,phosphorylated p38mitogen-activated protein kinase（p-p38）,adenosine monophosphate activated protein kinase（AMPK）,phosphorylated adenosine monophosphate activated protein kinase（p-AMPK）,silent information regulator factor-1（SIRT1）and peroxisome proliferator-activated receptor-γcoactivator-1ɑ（PGC-1ɑ）in the lung tissues of rats from each group were determined by Western blot,and statistical software was used to analyze whether there was significant difference in the protein expression in the lung tissue of each group.Results:Comparison of the levels of W / D and TLW in lung tissues of rats in each group :Compared with the Sham group,the W/D and TLW of the lung tissue of the IR group and S-IR group were significantly increased（all P values < 0.05）,and compared with the IR group,the S-IR group was significantly decreased（all P values < 0.05）.There was no significant difference between S-S group and sham group（all P values < 0.05）.（2）Pathological changes in the lung tissues of rats in each group : Histopathological sections of lung tissues in Sham group showed normal alveolar morphological structure,no inflammatory cell infiltration in the alveoli,and no fluid accumulation in the alveolar septa.Histopathological sections of the lungs in the S-S group showed grossly normal alveolar architecture,no obvious thickening of the alveolar walls,and no inflammatory cell infiltration in the alveolar septa,suggesting no significant damage.Compared with the Sham group,the histopathological sections of lungs from rats in the IR group showed severe destruction of alveolar morphological structure,extensive alveolar septal thickening,alveolar interstitium filled with a large amount of edema fluid and infiltrated with a large number of inflammatory cells.Compared with the IR group,inflammatory cell infiltration and edema were significantly reduced in the S-IR group.（3）Comparison of inflammatory and oxidative stress factor levels in lung tissue and serum of rats in each group : The contents of IL-1β,IL-6,TNF-α and MDA in IR group and S-IR group were higher than those in Sham group,while those in S-IR group were lower than those in IR group,all with statistically significant differences（all P values < 0.05）.The content of SOD in IR group and S-IR group was lower than that in Sham group,and the content of SOD in S-IR group was higher than that in IR group,all with statistically significant differences（all P values < 0.05）.There was no significant difference in the contents of IL-1β,IL-6,TNF-α,MDA and SOD between S-S group and Sham group（all P values > 0.05）.（4）Comparison of protein expression levels in lung tissues of rats in each group: Compared with Sham group,the expression levels of p-AMPK,SIRT1 and PGC-1ɑ protein in IR group and S-IR group decreased significantly,and the expression levels of p-p38 protein increased significantly,all with statistically significant differences（all P values <0.05）.Compared with IR group,the expression levels of p-AMPK,SIRT1 and PGC-1ɑ protein in lung tissue of S-IR group were significantly higher,and the expression level of p-p38 protein was significantly lower,all with statistically significant differences（all P values < 0.05）.There was no statistically significant difference in protein expression between S-S group and Sham group（all P values >0.05）.Conclusions:Distal limb ischemia-reperfusion can lead to obvious lung injury in rats.Sevoflurane preconditioning can protect lung injury induced by distal limb ischemia-reperfusion.Its mechanism may be related to reducing pulmonary inflammatory response and oxidative stress injury by promoting p-AMPK / SIRT1 /PGC-1ɑ signal pathway and inhibiting the expression of p-p38 protein. |
