Experimental Study Of Effect Of Vascular Endothelial Growth Factor On Development Of Lung And The Ductus Arteriosus

Part 1 Effect of vascular endothelial growth factor on synthesis of pulmonary surfactant[Abstract] Objective To study the effects of vascular endothelial growth factor (VEGF) on production of pulmonary surfactants. Method Fetal rat lungs were obtained at 19 days gestation. Primary culture of type II alveolar epithelial cells (AEC II) was performed using IgG panning technique. The experiment was divided into groups as VEGF, Dexamethasone, VEGF plus dexamethasone and a control, to determine total phospholipids, phosphatidylcholine (PC), phosphatidyl glycerol (PG) and sphingomyelin (SM). Result VEGF,Dexamethasone and VEGF plus dexamethasone groups showed increase amount of total phospholipids and its compositions on the day 1 of culture. VEGF plus dexamethasone group is the most highest in amount of total phospholipids. VEGF,Dexamethasone and VEGF plus dexamethasone groups increase signfinicantly phosphatidylcholine and sphingomyelin than control group. VEGF group and VEGF plus dexamethasone group can increase signfinicantly phosphatidyl glycerol than control group ,but dexamethasone group have not singnificant difference to compare with control group. Conclusion VEGF can better promoted the production and secretion of pulmonary surfactant of fetal rat than Dexamethasone. VEGF and Dexamethason can increase production of phospholipids in coordination. They may go through different mechanism for enhancement of synthesis of pulmonary surfactant,thereby improve biological function of AEC II. Part 2 The effect of vascular endothelial growth factor on expression of pulmonary surfactant protein B and VEGF with its receptors Flt-1, Flk-1 of alveolar epithelial cells type II.Objective To study the effect of the vascular endothelial growth factor(VEGF) on expression of pulmonary surfactant protein B and VEGF with its receptors Flt-1 Flk-1 of alveolar epithelial cells type II.Investigate the effect of its used in combination with Dexamethasone.Method Rat embryos were got from Wistar rats at 19 days gestation period. Primary culture of AEC II was done. The experiment was divided into VEGF group, Dexamethasone group, VEGF plus Dexamethasone group and control group, to determine the amount of VEGF with its receptors Flt-1 and Flk-1 and expression of pulmonary surfactant protein B by immunology histochemistry..Result SP-B prositive expression in VEGF group,Dexamethasone group and VEGF plus Dexamethasone group showed positive expression of SP-B; Control group showed negative expression of SP-B. VEGF group and VEGF plus Dexamethasone group showed positive expression of VEGF, Flt-1 and Flk-1;Dexamethasone group showed negative expression of VEGF, Flt-1 and Flk-1.Conclusion VEGF can promote synthesis and secret of pulmonary surfactant protein B; antagonises under-regulation of expression of AEC II receptors by Dexamethasone. However, whether it can reduce the side effect of Dexamethasone in lowering the lung to body weight ratio, reduction of formation of secondary alveolar septum, a waits further studies.part 3 Experimental study of the effect of vascular endothelial growth factor used in combination with Dexamethasone on development of lung of premature Wistar rats in vitroObjective Experimental study of the effect of vascular endothelial growth factor used in combination with Dexamethasone on development of lung of premature Wistar rats in vitro .To find the relationship of lung used vascular endothelial growth factor combination with Dexamethasone on development of premature. to explore the new path that prevent and therapy premature infant's ARDS. Method Wistar rat at 15 days gestation , Random divided into 4 groups , VEGF group, Dexamethason group,VEGF and Dexamethason group,control group. three rats any group。Content of total phospholipid,lecithin,sphyingomyelin,lysophosphatidy glycerin are measured by immunology histochemistry and thin layer chromatography. lung tissue were harvested and extracted for total RNA by Trizol reagent . mRNA levels of SP-B were measured by reverse transcription polymerase chain reaction (RT-PCR). Result Content of total phospholipid, lecithin, sphyingomyelin, lysophosphatidy glycerin are increased in any experiment group .VEGF,Dexamethasone and VEGF plus dexamethasone groups showed increase amount of total phospholipids,VEGF plus dexamethasone group is the most highest in amount of total phospholipids. Content of PC,PG have significant difference in VEGF group compared to control group, but content of SM have no significant difference.Content of PC, SM have significant difference in dexamethasone group compared to control group, but content of PG have no significant difference. SP-B mRNA levels were significantly increased in group VEGF group compared to Dexamethason group, VEGF group compared to VEGF and Dexamethason group, Dexamethason group compared to VEGF and Dexamethason group , VEGF and Dexamethason group compared to group control, P < 0. 01,have significantly difference .but VEGF group of SP-B mRNA levels have no significantly difference compared to group control ( P > 0. 05). Conclusion. VEGF can increase phospholipids of pulmonary surfactant, pulmonary surfactant protein synthesis and secret of the lung tissue in vitro , VEGF and Dexamethason have incoordination in production of phospholipids of pulmonary surfactant and pulmonary surfactant protein,but they have coordination function .VEGF and Dexamethason may both pass the different mechanism to increase pulmonary surfactant synthesis and improve function of the lung tissue,it is possible to prevent the ARDS occurrence by absence of pulmonary surfactant. Part 4 Experimental Study of the Effect of VEGF and Vitamin A on Development of the Ductus Arteriosus and lung in Fatal Rabbit.Objective To study the Effect of VEGF and Vitamin A on Development of the Ductus Arteriosus and lung in Fatal Rabbit,To explore the new path that prevent and therapy premature infant's patent ductus arteriosus. Method Eight time-bred rabbits were randomly assigned to three groups(2 rabbits each groups):It was used 3000U/kg VitA in gestational day 25 and VEGF0.1μg/㎏ alone and with contrast group (saline ). 10 fetal rabbits each group, fetch the lung tissue,ducts arterial of the fetal rabbits in the 27th day and amniotic fluid of the pregnant rabbits .The lung tissue and the amniotic lamellar bodies were assess the preterm fetal lung maturation .Some ducts arterial were used to find out the situation of the endometrium hyperplasia , Some were used to determine the calcium Concentration of the ducts arterial. Results VEGF group are significant different in the lung development than control group,but there was no significant difference on endothelial cell proliferation and the calcium concentration of the ductus arteriosus between VEGF group and control group. Endothelial cell proliferation on Vitamin A groups are significant thicker than control group. The calcium concentration of the ductus arteriosus on Vitamin A groups are higher than control group. Conclusion VEGF group can promote the lung maturation but it has no effects on the ducts arteriosus. Vitamin A can promote the ductus arteriosus development and increase calcium concentration of ductus arteriosus.