Effects Of Erythropoietin On Expression Of Chop And GRP78in Neonatal Rats With Hyperoxic Lung Injury

Objective:To exploe the effects of erythropoietin on expression of C/EBP homologous protein (CHOP) and glucose regulated protein (GRP78) in neonatal rats with hyperoxic lung injury.Methods:Ninety neonatal SD rats were randomly divided into three groups: air-exposed control (A group), hyperoxia-exposed placebo (85%oxygen)(B group), and hyperoxiaexposed Erythropoietin (EPO)-treated (C group),n=30/group. EPO (800U/kg) was administered3,7, and14days after hyperoxia exposure. The rats were randomly sacrificed3,7and14days after air or hyperoxia exposure for detecting the lung wet and dry weight ratio. CHOP, GRP78, B cell lymphoma-2(Bcl2) and Bcl-2associated X protein (Bax) levels were measured by Western blot. The assessment of lung histological changes by hematoxylin and eosin staining (n=9/group, each time point). Detected the activities of superoxide dismutase (SOD) and the level of malonic dialdehyde (MDA) by chemical colorimetric assay.Result:1. Comparing with Group A, the W/D specific values of each time-point for group B are significantly increased and the W/D specific values gradually increase with hyperoxia time extension, W/D specific values for group C are lower than the each time-point for group B and it has statistical significance (P<0.05).2. Lung tissue of group B has different levels of lung injury under the light microscope and the degrees of injury are more and more serious with hyperoxia time extension, the degrees of injury of each time-point for group C are more ease than group B.3. Western blotting shows that the protein expression of CHOP and GRP78for group B up-regulates with extending high oxygen exposure time compared with group A and its grey levels outstandingly increase, the protein expression of group C declines compared with group B, the protein expression of group B and group C on the seventh day and fourteenth day has statistical significance (P<0.05).4. The measurement of SOD and MDA shows that SOD values of group B have similar increases compared with group A, and the SOD values of each time-point for group C increase significantly and they have significant difference (P<0.05). In lung tissues for group C, the level of MDA is lower than group B and there are significant difference on the seventh day and fourteenth day.Conclusion:EPO can reduce high oxygen pulmonary edema and inflammation and regulate antioxidant enzymes and cell apoptosis factor expression, and it has protective effect for hyperoxia lung injury, and the mechanism relates to the protein expression of CHOP and GRP78related to lower endoplasmic reticulum stress.