Role of poly(ADP-ribose) polymerase-1 on lung ischemia-reperfusion injury in rats: the relationship with autophagy

Abstract

Objective To evaluate the role of poly(ADP-ribose) polymerase-1 (PARP-1) in lung ischemia-reperfusion (I/R) injury in rats and the relationship with autophagy. Methods Twenty-four clean-grade healthy male Sprague-Dawley rats, aged 8-12 weeks, weighing 200-240 g, were divided into 3 groups (n=8 each) using a random number table method: sham operation group (S group), lung I/R group (I/R group) and lung I/R plus PARP-1 inhibitor PJ34 group (I/R+ PJ34 group). The chest was only opened without clamping the left hilum of lung in group S. Lung I/R injury model was established by clamping the left hilum of lung for 45 min followed by 120 min reperfusion in I/R and I/R+ PJ34 groups.PJ34 10 mg/kg was intraperitoneally injected at 30 min before ischemia in group I/R+ PJ34, while the equal volume of normal saline was injected in S and I/R groups.The rats were sacrificed at the end of reperfusion, and 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), expression of PARP-1 activity markers (PAR), Bcl-2, Bax, microtubule-associated protein 1 light chain 3 Ⅰ (LC3-Ⅰ), LC3-Ⅱ and Beclin-1 (using Western blot). The apoptosis index, Bcl-2/Bax ratio and LC3-Ⅱ/LC3-Ⅰ ratio were calculated. Results Compared with S group, the W/D ratio, pathological scores, apoptosis index and LC3-Ⅱ/LC3-Ⅰ ratio were significantly increased, the expression of PAR and Beclin-1 was up-regulated, and Bcl-2/Bax ratio was decreased in I/R and I/R+ PJ34 groups (P<0.05). Compared with I/R group, the W/D ratio, pathological scores, apoptosis index, and LC3-Ⅱ/LC3-Ⅰ ratio were significantly decreased, the expression of PAR and Beclin-1 was down-regulated, and Bcl-2/Bax ratio was increased in I/R+ PJ34 group (P<0.05). Conclusion PARP-1 activation is involved in lung I/R injury in rats, and the mechanism may be related to increasing autophagy and inducing cell apoptosis. Key words: Poly(ADP-ribose) polymerases; Lung; Reperfusion injury; Autophagy