Comparison of the effects of antenatal dexamethasone and betamethasone on rat fetal lung morphogenesis

Abstract

Objective To explore the effects of low dose of dexamethasone and betamethasone administered antenatally on lung morphogenesis of rat embryo. Methods Fifteen pregnant rats were randomly assigned to 5 groups with 3 in each.The pregnant rats in 3-day-dexamethasone(Dex)group,saline intraperitoneal injection on the 16th,17th,18th day of gestation.One-day-Dex group and 1-daygestation,while received 4 ml saline on the 16th and 17th day.The lung tissues of embryo were stained with HE for morphometric measurements.The histological structures were observed with light microscope and transmission electron microscope. Results (1)Fetal lung in 1-day-Beta,3-day-Beta and 3-day-Dex group was more mature than control group under the light microscope.(2)Alveolar walls in the 3-day-Beta[(23.38±7.77)μm]and 3-day-Dex[(30.82±5.32)μm]and 1-day-Beta [(33.37±9.30)μm]were much thinner than those of the controls[(71.15±48.72)μm](P＜0.01).Respiratory thecal perimeter and alveolar space in 1-day-Beta group were(43.24±18.20)μmand(412.71±298.45)μm2,in 3-day-Beta group were(61.22±23.58)μm and(780.23±428.34)μm2,in 3-day-Dex group were(40.31±15.20)μm and(471.08±324.63)μm2,larger than controls [(32.06±11.40)μm and(285.70±175.77)μm2](P＜0,01).Compared with Dex group,Beta group had thinner alveolar walls but larger respiratory thecal perimeter and alveolar space(P＜0.01).(3)Under the transmission electron microscope,lamellar body in endochylema of type Ⅱ alveolar cell of the 1-day-Beta,3-day-Dex and 3-day-Beta group were more common compared with those of the controls.Obvious changes could be found in the 3-day-Dex and 3-day-Beta group. Conclusions Low dose of Dex and Beta can promote the development of rats fetal lung,and Beta iS better than Dex. Key words: Dexamethasone; Betamethasone; Lung; Embryonic development