Study On The Changes Of Platelet Mapks Signal Pathway In ARDS Rats

Objective:Acute respiratory distress syndrome(ARDS) is a special type of acute respiratory failure caused by a variety of causes of acute respiratory failure, which is a common clinical critical disease, difficult to treat, and the mortality rate is high. Although a lot of research has been done about it in recent fifty years, its detailed pathogenesis is still unclear. In recent years, it is found that hypercoagulation state exists in blood circulation in ARDS, and platelet activation may play an important role in the pathogenesis of ARDS.This study is intended to explore the signal transduction pathways of platelet activation in ARDS, provides a theoretical basis for clinical prevention and treatment of ARDS.Method:30 healthy SD rats were randomly divided into 5 groups. 4 groups of them were as the experimental group, 6 rats in each group, which were made ARDS rat models by intravenous injection of oleic acid(OA, 0.25ml/kg). The rats in experimental groups were killed after 2h, 6h, 24 h, 72 h of oleic acid injection separately. 1 of 5 groups was as control group, by intravenous injection of normal saline(NS) in same dose. The rats in control group were killed after 2h of saline injection. After the injection of saline for 2h or oleic acid for 2h、6h、24h、72h, the abdominal aorta blood sample of rats were taken; platelets were separated; platelet protein was extracted. Phosphorylation level about 3 of main protein kinases in mitogen-activated protein kinases(MAPKs) signal transduction pathway,JNK, ERK and p38 MAPK, were detected using the Western blotting method. After the sacrifice of animal, observe the changes of the lungs; weigh lung weight, calculate lung coefficient; isolated lungs, the right lung is drying after weighed, then weigh the dryweight, caculate the lung wet / dry weight ratio. The left lungs were fixed in 10% formalin for 1 week, to make pathological sections, HE staining for observe under light microscopy.The phosphorylation level of platelet protein kinase JNK, ERK, p38 MAPK were compared and analyzed with the pathological changes in lungs, to explore the changes of platelet MAPKs signal transduction pathway in ARDS, and the relationship between the changes and the pathogenesis of ARDS.Results:1. The changes of animal in general conditionThe rats of experimental groups began to have difficulty breathing, weaking, reducing activity, reducing eating and drinking after injection of oleic acid 2-3 minutes. After 24 h,the general state of the animals improved. To 72 h, activity of the animals returned to normal.The control group had no abnormal changes.2. The changes of lung coefficient and lung wet / dry weight ratioAfter injection of oleic acid for 2 ~ 24 h, the lung weight, lung coefficient and lung wet / dry weight ratio of the experimental groups increased in varying degrees, with the most serious in 2h group. All of the above in the control group had no abnormal change.3. The changes of pathology in lungsThe lungs of control group looks pink, normal size. 2 ~ 24 h experimental groups,the lungs were obvious swelling and had purple red flowers mottled appearance. 72 h group,the lungs looks white and gray, swelling degree reduced, the elasticity were poor.Under the microscope, 2 ~ 24 h experimental groups, there were a large number of red blood cells, white blood cells and fluid exudate in most alveolar cavities; and there were pink hyaline membrane in some alveolar cavities; Alveolar septa were thickening, there were telangiectasia, congestion, diffuse hemorrhage, microthrombi in small vascular, and a large number of inflammatory cells. 72 h group, the lesions were alleviated, but pulmonary fibrosis and pleural fibrosis emerged. The control group had no abnormal changes.4. The changes of phosphorylation level in platelet protein kinase JNK, ERKand p38 MAPKCompared with the control group, 2 ~ 24 h in experimental groups, the phosphorylation levels of the platelet protein kinase JNK, ERK, p38 MAPK were increased obviously. The highest phosphorylation expression of ERK and p38 MAPK was in 2h, the highest phosphorylation expression of JNK was in 6h, then gradually reduced(P<0.05).Conclusions:In experimental groups, the phosphorylation levels of the platelet protein kinase JNK,ERK and p38 MAPK increased obviously, regular pattern of changes were consistent with the changes of lung coefficient, lung wet / dry weight ratio and the changes of pathology in lungs basically. Which shows that platelet activation occurs in ARDS, and the activation process switches on the MAPKs signal transduction pathway.