地塞米松与倍他米松对大鼠胎肺形态发育影响的对比

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

目的比较产前小剂量应用地塞米松、倍他米松对大鼠胎肺形态发育的影响。方法15只孕鼠随机分成对照组、地塞米松治疗1d组、3d组和倍他米松治疗1d组及3d组，每组3只。地塞米松及倍他米松3d组分别于妊娠第16、17、18天连续腹腔注射地塞米松或倍他米松，剂量为0．2mg／（kg·d）；地塞米松及倍他米松1d组于妊娠第16、17天腹腔注射4ml生理盐水，妊娠第18天给予相应剂量药物。对照组大鼠于妊娠第16、17、18天连续注射4ml生理盐水。光镜及电镜观察各组孕鼠的胎仔肺组织形态发育变化。结果（1）与对照组相比，倍他米松3d、1d组及地塞米松3d组肺泡结构发育较为成熟。（2）倍他米松3d组的肺泡间隔为（23．38±7．77）μm，地塞米松3d组为（30．82±5．32）μm，倍他米松1d组为（33．37±9．30）μm，均小于对照组[（71．15±48．72）／lm]（P〈0．01）；倍他米松1d组的呼吸膜周径为（43．24±18．20）μm、肺泡表面积为（412．71±298．45）μm^2，倍他米松3d组分别为（61．22±23．58）μm和（780．23±428．34）μm^2，地塞米松3d组分别为（40．31±15．20）μm和（471．08±324．63）μm^2，均大于对照组[分别为（32．06±11．40）μm和（285．70±175．77）μm^2]（P〈0．01）；倍他米松1d组与地塞米松1d组相比肺泡间隔薄，呼吸膜周径及肺泡表面积增大（P〈0．01）。倍他米松3d组与地塞米松3d组相比肺泡间隔薄（P〈0．01），呼吸膜周径及肺泡表面积增大（P〈0．01）。（3）透射电镜观察发现，倍他米松1d、3d及地塞米松3d组肺泡Ⅱ型上皮细胞内可见板层小体，以倍他米松和地塞米松3d组改变最为明显，而对照组未见板层小体。结论小剂量地塞米松、倍他米松均能促进胎肺发育，但倍他米松效果更好。

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, 3-day-betamethasone （Beta） group and control group received 0. 2 mg/（kg · d） of Dex or Beta or 4 ml saline intraperitoneal injection on the 16th, 17th, 18th day of gestation. One-day-Dex group and 1-day-Beta group received 0.2 mg/（kg · d） of Dex or Beta intraperitoneal injection on the 18th day and of gestation, 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） μm and （412.71 ±298. 45） μm^2 , in 3-day-Beta group were （61.22 ±23.58） μm and （780. 23 ± 428.34） μm^2 ,in 3-day-Dex group were （40.31±15.20） μm and （471.08±324.63）μm^2 , larger than controls [（32.06±11.40） μm and （285.70±175.77） μm^2] （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.