Effect of melatonin pretreatment on cell apoptosis and autophagy during lung ischemia-reperfusion in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of melatonin pretreament on cell apoptosis and autophagy during lung ischemia-reperfusion (I/R) in rats.Methods Thirty-six adult male Sprague-Dawley rats,weighing 230-280 g,were divided into 3 groups (n=12 each) using a random number table method:sham operation group (group Sham),pulmonary I/R group (LIR group) and melatonin pretreatment group (MLT group).Lung I/R injury model was established by clamping the left hilum of lung for 60 min followed by 2 h reperfusion in LIR and MLT groups.Melatonin 1 mg/100 g was intraperitoneally injected at 15 min before clamping the left hilum of lung in group MLT.The rats were sacrificed at the end of reperfusion,the left lung was lavaged and the broncho-alveolar lavage fluid (BALF) was colleted for determination of protein concentrations.Lungs were removed for microscopic examination of the pathological changes (with a light microscope) which were scored and for determination of wet to dry weight ratio (W/D ratio),cell apoptosis (by TUNEL) and expression of Bcl-2,Bax,microtubule-related protein 1 light chain 3B Ⅰ (LC3B Ⅰ),LC3B Ⅱ,Beclin-1 and phosphorylated mammal rapamycin target protein receptor (p-mTOR) (using Western blot).The apoptosis index,Bcl-2/Bax ratio and LC3B Ⅱ/LC3B Ⅰ ratio were calculated.Results Compared with Sham group,the protein concentration in BALF,W/D ratio of lung tissues,apoptosis index,LC3B Ⅱ/LC3B Ⅰ ratio and Beclin-1 expression were significantly increased,and Bcl-2/Bax ratio and p-mTOR expression were decreased in LIR and MLT groups (P＜0.05).Compared with LIR group,the protein concentration in BALF,W/D ratio of lung tissues,apoptosis index,LC3B Ⅱ/LC3B Ⅰ ratio and Beclin-1 expression were significantly decreased,and Bcl-2/Bax ratio and p-mTOR expression were increased in MLT group (P＜0.05).Conclusion The mechanism by which melatonin pretreatment mitigates lung I/R injury may be related to inhibiting cell apoptosis and autophagy in rats.