Expression And Significance Of Foxa₂ In Premature Rats Lung With Hyperoxia-induced Chronic Lung Disase

Objective:Through the establishment of the model for chronic hyperoxia in premature rat lung injury, to investigate the expression and significance of Foxa2 in premature rats lung with hyperoxia-induced chronic lung disase.To research the relationship between the Foxa2 and the mature of premature rat lung, and to research the function of the Foxa2 in chronic hyperoxia in premature rat lung injury.Methods:(1)The premature rats were from the rats which were pregnant of 21 days. Sixty premature rats were randomly exposed to hypemxia (experimental group)and to room air (Control group) (n=30 each) according to the fraction of inspiratiory.The mean weight were respectively (4.84±0.13) g,(4.83±0.12) g,not limited to male and female. In the experimental group, the premature rats (with the female mouse) would be placed on oxygen tank afer birth,continualy input in oxygen to maintain the FiO2 to 95%(with measured oxygen equipment monitoring),the temperature to 25-27℃, and the humidity to 50%-70%. The premature rats were put out of the box 30 minutes per 24h, fed and changed litter, and exchanged the female mouse with the control group in order to avoid reducing the ability to feed because of oxygen toxicity.The control group,maintained the FiO2 to 21%,was in the same with the experimental group in the specific methods and experimental control factors. (2)In the experiment of 1,3,7 day, respectively, the premature rats which were randomly selected 10 in the experimental group and the control group were killed after anesthesia.After the lung lavaged, the lung tissue would be removed and placed in 4% paraformaldehyde fixed,ethanol dehydrated progressively,embedded in paraffin sections and HE stained. The pathological change of the lung tissue was observed and the degree of pulmonary fibrosis was determinated with double-blind score by the microscope. The expression of Foxa2 in the lung tissue was observed in immunohistochemistry.The results of immunohistochemistry would be semi-quantitative analysis using Motic digital medical image analysis system and Meta Morph software. (3)All parameters were expressed as the mean value±standard difference(x±S), statistical analysis were carried out by the use of the least significant difference. Difference was considered significance when the p.value was less than 0.05. The statistics work were finished by spss13.0 software. Results:(1)The pathological change of the lung tissue:the control group of 1,3,7day, the lung tissue gradually matured, which the alveolar structure regulared gradually and the alveolar septum thinned. Compared with the control group,on the first day of the experimental group, the alveolar space were large and not the rules, the alveolar intervals were few and thick. On the third day of the experimental group, the alveolar cavity and alveolar inflammatory cells were a little leakage, on the seventh day, the alveolar septum was thinned, the alveolar structure was simplified and some pulmonary interstitial was fibered. For 1d, the experimental group and control group were no significant difference in the degree of pulmonary fibrosis(t=0.97,P>0.05), for 3d,7d, the pulmonary fibrosis score was significantly higher (P<0.05). (2) The expression of Foxa2 in the lung tissue:On 1,3,7 day, compared with the control group,the immunohistochemistry showed that the expression of Foxa2 gradually increased in the pulmonary interstitial and alveolar septa with the lung tissue continuning to mature, the seventh day, a large number of Foxa2 would be seen. In the experimental group, the expression of Foxa2 was a downward trend with the lung tissues of oxygen increased.The first day, the expression of Foxa2 was obvious and was not significant differences with the control group(P=0.01); the third day,the expression of Foxa2 in the lung tissue were significantly reduced; with the lung tissue aggravated, the seventh day, the expression of Foxa2 in lung tissue was very weak, which was expressed in only a small number of lung interstitial and alveolar septa and some distribution was extremely uneven (3d,p=0.001;7d, p=0.000). Conclusion:Forkhead box(Fox)proteins characterized by a conserved winged-helix DNA binding domain constitute a large family of transcription factors,which is the important gene material regulated a group of lung surfactant protein production to promote the premature rat lung development; (2) After inhaled hyperoxic and the expression of Foxa2 inhibited,The lung development can be obstructed,and then the lung injury occurred.