Protective Effect And Mechanism Of Alprostadil On Acute Respiratory Distress Syndrome Induced By Oleic Acid In Rats

Aim:The aim of this study is to investigate the role and mechanism of alprostadil in acute respiratory distress syndrome(ARDS)induced by oleic acid(OA)in rats and provide theoretical basis for clinical application.Methods:The rats were randomly divided into five groups:control group,OA model group,alprostadil low-dose group(2.5μg/kg),alprostadil medium-dose group(5μg/kg)and alprostadil high-dose group(10μg/kg),6 per group,30 in total.Preparation of oleic acid model in rats:The ARDS model was induced by the injection of O.lml/kg oleic acid into femoral vein.Alprostadil group:after injection of 0.1ml/kg oleic acid into vein,alprostadil injection(2.5,5,10μg/kg)was dissolved in saline solution and injected slowly.Control group:equal volume of saline was injected into the femoral vein.After the experiment,the left lung tissue was removed and the wet weight was determined to calculate for the lung weight.Left lung tissue was weighed and then dried in an oven at 68℃ for 48h and the dry weight was determined.The wet and dry weights were then measured to calculate the lung W/D.Right middle lobe lung tissue were fixed in formaldehyde for 48h and were then dehydrated,embedded in paraffin wax,sections,HE and Masson trichrome.The pathological changes were observed under a microscope.The remaining right lung tissue were stored at-80℃.The expression of TNF-α、IL-1β、ACE、Bcl-2、Bax、NF-κB p65、NF-κB p-p65、p38 MAPK、p-p38 MAPK、ERK1/2、p-ERKI/2、JNK and p-JNK protein in lung tissue were evaluated by western blot.Results:1.Rats injected with oleic acid in the femoral vein experienced a marked increase in respiratory rate,cyanosis of the lips,and respiratory distress.At the same time,the nasal cavity overflowed with a pink foam-like pulmonary edema fluid.Visual observation of lung tissue showed that the lungs of the control group were pink,without congestion and edema;the surface color of lungs in the oleic acid model group was dark red,the lung tissue volume was significantly increased,and the congestion and edema were obvious;the alprostadil group was compared with the oleic acid model group,the volume of the lungs decreased,and the congestion and edema improved.The improvement was most obvious in the high-dose group.2.Compared with the control group,the W/D of left lung in the oleic acid model group increased significantly(P<0.005).Compared with the oleic acid model group,the W/D of left lung in the low and middle-dose group of alprostadil was decreased(P>0.05);and the W/D of left lung in the high-dose alprostadil group was significantly lower(P<0.05).3.HE staining showed that compared with the control group,the oleic acid model group showed increased exudation in the alveolar cavity,congestive expansion of the pulmonary capillaries,alveolar wall thickening,hyaline membrane could be seen in several alveolar,congestion and edema of pulmonary interstitial and alveolar inflammatory cell infiltration,lung injury score was significant increased(P<0.05).Compared with the oleic acid model group,the lung histopathological changes and lung injury scores did not change significantly in the low-dose alprostadil group(P>0.05);the lung histopathological damage and lung injury scores were reduced in the alprostadil middle-dose group(P<0.05).In the previous high-dose levitol group,the degree of pathological injury reduction and lung injury scores were significantly reduced(P<0.01).4.Masson staining results showed that compared with the control group,blue collagen fiber deposition was significantly increased in the alveolar septum of the oleic acid model group.Some of them were fused into small pieces or ribbons,and collagen deposition was evident in the lung tissue.Lung fibrosis score was significant.Increased(P<0.05).Compared with the oleic acid model group,the blue collagen fibers and lung fibrosis scores in the alveolar septum of the alprostadil low-and middle-dose group were decreased(P>0.05);the blue collagen fibers and lungs in the alveolar space of the high-dose levifel group were previously The reduction in fibrosis scores was more pronounced(P<0.05).5.Westem blot results showed that compared with the control group,the TNF-a and IL-1β protein expressions in the oleic acid model group were significantly increased(P<0.05),and phosphorylation of p38 MAPK,ERK1/2,and JNK were significantly upregulated(P<0.05).phosphorylation of NF-κB p65 was significantly increased(P<0.005),expression of pro-apoptotic protein Bax was significantly increased,expression of anti-apoptotic protein Bcl-2 was significantly decreased(P<0.05),and ACE protein expression was significantly increased(P<0.05).Compared with the oleic acid model group,the expression of TNF-a and IL-1β protein in the lung tissue of the high-dose levofite group was significantly reduced(P<0.05).The phosphorylation of p38 MAPK,ERK1/2,JNK and phosphorylation of NF-κB p65 were significantly down-regulated(P<0.05),the expression of pro-apoptotic protein Bax was significantly down-regulated(P<0.05),and the expression of anti-apoptotic protein Bcl-2 was significant up-regulated,ACE protein expression decreased more significantly(P<0.05).Conclusions:1.Alprostadil could paly a protective role through the following ways:inhibits the expression of TNF-α and IL-1β protein in lung tissue of ARDS induced by oleic acid in rats,down-regulates NF-κB signaling pathway,inhibits the activation of MAPKs signaling pathway,decreases the expression of ACE protein,and inhibits the expression of lung tissue fibers,improve the degree of pulmonary edema and down-regulate apoptosis of lung tissue,especially in the high-dose group was significant.2.Alprostadil has a certain therapeutic effect on ARDS caused by oleic acid,which provides a theoretical basis for clinical treatment of ARDS.