Effects of FTY720 pretreatment on lung injury induced by limb ischemia-reperfusion in rats

Abstract

Objective To evaluate the effects of FTY720 pretreatment on lung injury induced by limb ischemia-reperfusion (I/R) in rats. Methods Thirty healthy male Sprague-Dawley rats, weighing 230-260 g, were divided into 3 groups (n=10 each) using a random number table: sham operation group (group S), I/R group and FTY720 group (group F). Bilateral hind limb I/R was induced by applying rubber band tourniquet high around each thigh for 3 h followed by 3 h of reperfusion.FTY720 was given by intragastric gavage at 3 mg·kg-1·d-1 for 7 consecutive days before I/R in group F, while the equal volume of normal saline was given instead in group I/R.At the end of reperfusion, blood samples were collected from the carotid artery for blood gas analysis, and oxygenation index (OI) was calculated.The rats were then sacrificed and lungs removed for examination of pathological changes (with light microscope) and for determination of apoptosis rate (using flow cytometry) and expression of CCAAT/enhancer-binding protein homologous protein (CHOP), caspase-12, c-Jun N-terminal kinase (JNK), Bcl-2 and Bax protein in lung tissues (using Western blot). Bax/Bcl-2 ratio was calculated. Results Compared with group S, OI was significantly decreased in group I/R, and apoptosis rate was increased, the expression of CHOP, caspase-12, JNK and Bax protein was up-regulated, and the expression of Bcl-2 was down-regulated, and Bax/Bcl-2 ratio was increased in I/R and F groups (P<0.05). Compared with group I/R, OI was significantly increased, apoptosis rate was decreased, the expression of caspase-12, CHOP, Bax and JNK protein was down-regulated, and the expression of Bcl-2 was up-regulated, and Bax/Bcl-2 ratio was decreased in group F (P<0.05). The pathological changes of lungs were significantly attenuated in group F as compared with group I/R. Conclusion FTY720 pretreatment can attenuate lung injury induced by limb I/R in rats, and the mechanism may be related to inhibition of endoplasmic reticulum stress-related cell apoptosis. Key words: Extremities; Reperfusion injury; Respiratory distress syndrome, adult; FTY720