兔宫内感染模型地塞米松处理后母胎组织的形态学改变

Maternal-fetal outcomes after maternal treatment with Dex in model of intrauterine infection in rabbits

目的 了解产前母体地塞米松处理是否加重妊娠母 胎组织感染 ,并比较其在非感染和感染条件下对胎肺发育的影响。方法 于妊娠第 2 4天建立兔宫内感染模型 ,并于模型建立当天开始耳静脉注射地塞米松和先锋霉素 ,连续用药 3d。于妊娠2 7d留取胎肺、胎盘、母体子宫和肺组织进行形态学检查。结果 无论感染模型还是非感染模型 ,地塞米松处理组胎肺均比对照组胎肺的肺泡腔更大、更均匀 ,而肺泡间隔更薄 ,地塞米松处理后胎肺肺泡腔的表面积明显大于对照组 ,而肺泡间隔表面积明显小于对照组 (P <0 .0 5 )。超微结构显示感染模型地塞米松处理组胎肺的Ⅱ型细胞内板层体数目多于对照组 ,但相对于非感染模型地塞米松处理组则有所减少。地塞米松组胎肺和胎盘的感染程度均明显重于对照组 (P <0 .0 5 ) ;而母体子宫和母肺的感染程度有高于对照组的趋势。此外 ,地塞米松组发生早产和胎仔死亡的孕兔数明显高于对照组 (P <0 .0 5 )。结论 Dex产前处理可促进兔胎肺形态发育和Ⅱ型上皮细胞成熟 ,但在宫内感染情况下 ,其促胎肺发育的作用会受到一定程度的影响 ,且具有加重母 胎组织的感染程度、加速早产发生及增加胎儿死亡的可能。因此 ,在感染或可疑感染的情况下 ,临床应慎重使用地塞米松促胎肺成熟。

Object To study the effects of prenatal maternal treatment with dexamethasone(Dex) on infection in maternal-fetal tissues in model of intrauterine infection,and to compare its effect on the development of fetal lungs in model of intrauterine infection with that in model without intrauterine infection in rabbits.Method The model of intrauterine infection in pregnant rabbits was established at 24d of gestation.Then,the rabbits were treated continuely with Dex in combination with cefamezin for 3d.The tissue samples of the fetal lungs,plancenta,maternal uteri and lungs were collected and observed with microscope and electron microscope.Results Larger and more uniform alveolar air spaces in size with thinner alveolar septa were found on 27d fetal lungs from Dex -treated groups when compared with the control groups in both infection and uninfection models.The surface area of the alveolar air spaces in Dex -treated fetal lungs was significantly larger,and the surface area of the alveolar septa was smaller as comparison to that in the control.Alveolar type Ⅱ cells of Dex -treated fetal lungs contained more lamellar bodies and less glycogen as compared with that of the control group.The infective degree of fetal lungs and placenta from Dex-treated group was apparently higher than that from the control group(P<0.05).The number of pregnant rabbits with preterm delivery and fetal death in Dex -treated groups significantly larger when compared with that in the control.Conclusion Prenatal maternal treatment with Dex between 24d and 26d gestation can stimulate the morphogenesis of fetal lung and the maturation of alveolar type Ⅱ cells in rabbits.In model of intrauterine infection of rabbits,but the effects may be limited at some degree with its side effects.In addition,Dex can aggravate infection in maternal-fetal tissues and accelerate preterm delivery.These results suggest clinicians should use this hormone carefully for preventing and treating RDS.