Effects Of Vitamin D Intervention In The New Born Rats Of Bronchopulmonary Dysplasia During Early Life

Objective:To observing the effects of vitamin D on SD newborn rats of bronchopulmonary dysplasia animal models which caused by high oxygen.We check the different time of the lung tissue pathology,the mRNA expression of angiogenesis factor?VEGF?,surfactant protein-A?SP-A?and surfactant protein-B?SP-B?,then explore the appropriate vitamin D dose to the newborn BPD rats models in the aspect of adjuvant and the intervention mechanism in BPD prevention.Methods:The 43 SD pregnant rats were randomly divided into four groups:air group?n=6?,high oxygen group?95%O₂ concentration,n=6?,low doses VitD group?0.25 mg/kg,n=12?and high doses VitD group?0.5mg/kg,n=12?.Selected half amounts of the pregnant rats respectively from each intervention groups for the BPD model,and the remaining half prengnant rats for exchange with female rats in their own group,the least seven pregnant rats were raised in the air to exchange with the female rats of the hyperoxic group.The two Vit D intervention groups were treated with low doses VitD group?0.25 mg/kg?and high doses VitD group?0.5 mg/kg?by gavage respectively at day 17,18 and 19,while the other two groups were treated with 1ml saline.In order to establish the bronchopulmonary dysplasia?BPD?animal model,the female rats and their babies were put into the high oxygen boxes after birth.The newborn rats were treated with VitD?1 ng/g and 3 ng/g?respectively via intraperitoneal injection,the other two groups supplement saline with the same method.All the newborn rats weights were taken,assess the condition of the newborn rats and their lung tissues were obtained at day 3,5 and 9 after birth.Part of the tissues were paraffin embedded and stained by hematoxylin-eosin for observing pathological changes,and the mRNA expressions of VEGF,SP-A and SP-B were detected by RT-PCR method.Results:The survival rate of the normal group was the highest than the others,while the high oxygen group was the lowest,the survival was the closest to the normal group.Compared with the normal group,the average weight of newborn rats for the high dose group was lower,but it was higher than the higher oxygen groups and the low dose VitD groups at day 3,5 and 9 respectively,and the differences were both statistically significant.By observing the HE staining results,alveolar structure of the high oxygen group were irregularly arranged and simplified,the alveolar wall tissue was thickened more significantly and a large amount of inflammatory cells were infiltrated compared with the other groups,while the development of high dose VitD group is more close to the normal group.Compared with the newborn rats in high oxygen group and low dose VitD group at day 3,5 and 9,the VEGF and SP-A expression levels of high dose VitD group were the highest,the differences were both statistically significant.Compared with the newborn rats in high oxygen group and low dose VitD group at day 5 and 9,respectively,the SP-B expression levels of high dose VitD group was higher than the newborn rats of the high oxygen group and low dose VitD group with the same age,the differences were both statistically significant.Conclusions:1.Exposures to high oxygen environment long-term can inhibite the normal development of lung in neonatal rats.2.By given proper vitamin D intervention in the early stage of life,it might have protective effect on the occurrence of the bronchopulmonary dysplasia in the newborn rats by upregulating the expression levels of VEGF,SP-A and SP-B.