产前给予地塞米松对仔鼠肺泡上皮细胞基底膜的影响

目的　观察产前注射地塞米松对仔鼠肺泡发育的影响。方法　SD孕大鼠于孕18,19,2 0dim地塞米松0 .8mg·kg- 1·d- 1,出生后4和10d仔鼠取肺,做组织切片免疫组化染色,图像分析Ⅳ型胶原的分布和表达强度。电镜观察仔鼠肺泡上皮细胞基底膜。结果　电镜下,正常4d仔鼠外周肺组织上皮细胞基底膜变薄,不连续,胞浆伸出伪足进入间质,与成纤维细胞靠近、接触。地塞米松组4d仔鼠外周肺组织上皮细胞的基底膜的不连续现象较少,上皮间质的直接接触较少。正常仔鼠肺泡上皮细胞基底膜Ⅳ型胶原的表达呈不连续线状,间有缺损,量较少,色较浅;地塞米松组仔鼠肺泡上皮细胞基底膜的Ⅳ型胶原表达较多、色较深、呈连续线状,阳性强度明显上调。结论　孕后期用地塞米松影响仔鼠肺泡上皮细胞基底膜Ⅳ型胶原表达,抑制基底膜发育,从而影响肺泡正常发育。

Effect of prenatal administration of dexamethasone on basement membrane of lung epithelial cells in newborn rats

AIM To investigate the effect of prenatal administration of dexamethasone (DEX) on the development of pulmonary alveoli in newborn rats. METHODS Eight Sprague-Dawley (SD) pregnant rats were divided i nto DEX group and control group with four rats each; on d 18, d 19, d 20 followi ng gestation, the animals were injected im with DEX (0.8 mg·kg^-1·d^-1) or isotonic saline (0.5 mL). After natural parturition, the lungs of new born rats at age of 4 and 10 d were examined. Immunohistochemical studies of lun g typeⅣ collagen were performed, and analyzed by a digital image analysis system. Transmission electron microscope was used to observe the basement membrane of lung epithelial cells of 4 d-old rats. RESULTS Electron-microsco pic examination revealed that the basement membrane of lung epithelial cells tur ned thin and discontinuous, resulting in close contact of epithelial cells with fibroblasts in 4 d control rats. In DEX group, the discontinuous basement membra ne and close contact of cells were seldom seen. The immunohistochemical expressi on of typeⅣ collagen in control group was discontinuous and linear in the lung basement membrane of 4, 10 d rats, its expression was less and weak. In DEX grou p, the expression of type Ⅳ collagen increased significantly. CONCLUSION Prenatal DEX administration can affect the expression of typeⅣ collagen in the lung basemet membrane of newborn rats, inhibit the development of basement membrane.