C/EBP α在妊娠期糖尿病大鼠胎肺成熟过程中的作用

The effect of CCAAT enhancer binding protein α on lung maturation of the fetuses from STZ-induced diabetic pregnancy rats

目的:探讨CCAAT/增强结合蛋白α(C/EBP α)在妊娠期糖尿病(GDM)大鼠胎肺成熟过程中的作用。方法:将SD孕鼠随机分为妊娠期糖尿病组(GDM组)和对照组。GDM组给予链脲佐菌素行腹腔注射建立GDM模型,每隔一天检测孕鼠的血糖及体重。于孕21天剖宫产取出胎鼠,记录胎鼠体重、数量及胎仔血糖。HE染色观察胎鼠肺组织病理改变,油红O染色检测胎鼠肺组织中脂质的变化情况,透射电镜观察胎鼠肺组织超微结构改变,免疫组化法检测胎鼠肺表面活性物质相关蛋白A(SP-A)和C/EBP α表达情况,RT-PCR法检测SP-A和C/EBP α mRNA表达。Western blot法检测SP-A和C/EBP α蛋白表达。结果:GDM组孕鼠和胎鼠血糖均显著高于对照组,孕鼠体重、胎鼠体重及胎仔量均显著低于对照组,差异均有统计学意义(P均<0.000)。GDM组胎鼠肺泡数和肺泡面积均显著低于对照组,肺泡间隔大于对照组,差异均有统计学意义(P<0.000)。GDM组胎鼠肺组织中AECⅡ内的板层小体数明显减少,大量糖原颗粒聚集,细胞表面的微绒毛明显减少。油红O染色见胎鼠肺组织中脂滴数明显减少。SP-A和C/EBP α的mRNA和蛋白表达水平显著低于对照组,差异有统计学意义(P均<0.05)。结论:GDM胎肺组织中C/EBP α表达降低,抑制了SP-A和脂质生成,阻碍了细胞内糖原转化成脂质。胎肺组织中C/EBP α表达降低可能是GDM胎鼠肺发育延迟的发病机制之一。

Objective：To investigate the effect of CCAAT enhancer binding protein αon lung maturation of the fetuses from STZ-induced diabetic pregnancy rats.Methods：Pregnant Sprague-Dawley rats were randomly divided into diabetic and control group. Diabetic pregnancy was induced by a single intraperitional injection of streptozotozin.The blood glucose and weight of the pregnant rats were monitored every other day during the gestation.Fetuses were delivered successively by cesarean section on day 21 of pregnancy.The blood glucose,body weight and litter size were recorded. The morphological alterations of fetal lungs were observed by using HE staining.The lipid accumulation in fetal lungs was evaluated by Oil red O staining. The ultrastructures of the fetal lungs were observed by transmission electron microscope.The expressions of SP-A and C/EBP α were detected by immunohistochemistry.The expressions of SP-A and C/EBP α gene were analyzed by RT-PCR. The expressions of SP-A and C/EBP α protein were measured by Western blot. Results： Blood glucose level of female rats and fetal rats in GDM were significantly higher than those of the control group（ P〈0.000）,while body weights of the pregnant rats and fetal rats in GDM group were lower than that in the control group（ P〈0.000）.The Litter size in GDM was significantly reduced compared with the control group（ P〈0.000）.The mean alveolar numbers and pulmonary alveolar area of GDM group were significantly lower than those of the control group（ P〈0.000）.The width of alveolar septa in GDM group was thicker than that in the control group（ P〈0.000）. In GDM group,the volume of the AEC Ⅱ cells（the alveolar type Ⅱ cells）were significantly smaller than control group,and the shape of AECⅡ cells became flat and accompanied with decreased lamellar body,abundant glycogen accumulated in the cytoplasm.The microvilli on the surface of the alveolar type Ⅱ cells were obviously reduced.The mRNA and protein expressions of SP-A and C/EBP α of fetal lung in GDM group were significantly decreased compared with that in the control group（ P〈0.05）. Conclusions：The decreased expression of C/EBP α in GDM fetal lung inhibited the production of SPA and lipid,which prevents intracellular glycogen from transforming into lipids. The decreased expression of C/EBP in fetal lung tissue may be one of the pathogenesis of delayed development of GDM fetal lung.