Objective To investigate the effect of Rhubarb on bronchopulmonary dysplasia(BPD) and its potential mechanism.Methods Neonatal Sprague-Dawley rats (postnatal day 4) were exposed to 600 mL/L 02 to induce BPD.The experimental rats were randomly divided into 4 groups with 16 in each group:air + saline group,air +Rhubarb (600 mg/kg)group,and hyperoxia + saline group,and hyperoxia + Rhubarb group.The rats were sacrificed and lung tissues were obtained on day 14 and 21 after birth.Hematoxylin-easin staining was used to detect the pathomorphology of the lungs.Apoptosis of the lung tissue was detected by means of TdT-mediated dUTP nick-end labeling (TUNEL).The expression of Fas was detected by adopting Western blot.The activity of Caspase-8 and Caspase-3was detected by using spectrophotometer.Results The lung structure of rats was markedly abnormal (decreased,enlarged and simplified alveoli) after being exposed to hyperoxia at any time point.The apoptosis indexes (39.91 ± 1.91vs.10.11 ± 1.64,48.80 ± 4.51 vs.12.90 ± 3.18),the expression levels of Fas (0.47 ± 0.02 vs.0.21 ± 0.01,0.55 ±0.02 vs.0.22 ±0.01) and the activities of Caspase-8 (52.59 ± 1.23 vs.40.74 ± 1.08,60.20 ± 3.48 vs.40.39 ±2.47) and Caspsase 3 (57.17 ± 1.88 vs.42.00 ± 1.19,64.57 ± 2.79 vs.41.54 ± 1.27) were all increased in the hyperoxia + saline group compared with those in the air + saline group on day 14 and 21,and the differences were statistically significant(all P ＜ 0.001).However,compared with the hyperoxia + saline group,Rhubarb administration dramatically decreased pulmonary apoptosis index (26.49 ± 2.65 vs.22.97 ± 3.66),Fas protein level (0.27 ± 0.03 vs.0.31 ± 0.01) and the activity of Caspase-8 (32.70 ± 2.69 vs.30.66 ± 4.48) and Caspase-3 (44.94 ± 1.60 vs.44.59 ± 1.66),and the differences were statistically significant (all P ＜ 0.001).Meanwhile,lung damage after hyperoxia was significantly attenuated in the hyperoxia + Rhubarb group.Conclusion Rhubarb can reduce the hyperoxic lung injury of BPD by reducing the apoptosis of newborn rat lung tissue cells,and the mechanism may involve the apoptosis pathway of Fas.