EGF和TRH对不同时间胎肺SP-B基因表达的影响

Effects of EGF and TRH on SP-BmRNA expression in fetal lung at different gestation time

目的探讨表皮生长因子(EGF)和促甲状腺激素释放激素(TRH)对胎肺SP-B基因表达的影响,并与地塞米松(Dex)进行比较。方法采用兔作动物模型,产前分别给予EGF、TRH及Dex处理,通过RT-PCR及Southern印迹分析检测第25天和27天胎肺的SP-B mRNA,电镜观察胎肺板层体的形成。结果EGF、TRH和Dex处理组胎肺SP-B mRNA水平明显高于对照组,各处理组之间无显著差别,但在第25天SP-B mRNA表达仅见于Dex处理组。超微结构显示TRH、EGF和Dex处理组第27天的胎肺不仅含有板层体的Ⅱ型上皮细胞的数量显著多于对照组,而且单个Ⅱ型上皮细胞内的板层体数目也多于对照组。妊娠第25天,除Dex处理组可观察到个别Ⅱ型上皮细胞含有少量不成熟板层体外,其余处理组和对照组内均未发现。结论在妊娠第27天,EGF和TRH均能促进兔胎肺SP-B表达,其作用程度与Dex接近,但在妊娠更早时间,EGF和TRH对SP-B的促进作用不如Dex显著。胎肺SP-B mRNA可检出和升高时间与板层体出现和增加时间一致,SP-B mRNA可能是胎肺成熟的标志。

Objective Sduty on the effects of EGF and TRH on SP-B mRNA in fetal lung, and compare their efficacy with dexamethsone（Dex）. Methods Pregnant rabbits were treated respectively by EGF, TRH and Dex. SP-B mRNA in their fetal lung were detected with RT-PCR and Southern blotting. Lamellar bodies were observed by electron microscope. Results SP-B mRNA level in 27th gestation day lung from EGF, TRH and Dex treated groups were significantly higher as compared with that from the control, but no significant difference among the three treated groups. However, only Dex appeared to increase the SP-B mRNA levels, and SP-B mRNA in other treated groups and in the control group was undetectable in 25th day fetal lung. The uhrastructural features showed that alveolar type Ⅱ cells in each treatment group contained more lamellar bodies than thant in control group. However, only few type Ⅱ cell of Dex-treated fetal lungs contained less and small, lamellar bodies in 25 day lung. The other treated groups and the control group showed no any lamellar body. Conclusion EGF, TRH and Dex can promote SP-B expression in fetal lung at 27th gestation day, and their effects have no significant difference, but at more early time, their efficacy less than that of Dex. The time when SP-B mRNA can be detectable and rise was coincident with the time that lamellar body appear and increase in fetal lung, so SP-B mRNA may be as a mark of fetal lung maturation.