被动吸烟诱导的胎儿生长受限大鼠胎盘血管结构异常及其机制

Abnormal Placental Vascular Structure in Smoking-induced FGR and the Mechanism

目的研究被动吸烟诱导的胎儿生长受限(fetal growth retardation,FGR)大鼠胎盘血管结构的异常及其分子机制。方法采用被动吸烟法建立大鼠FGR模型,将12只孕鼠随机分为正常组(n=6)和FGR组(n=6),每只孕鼠取3个胎盘检测(即每组n=18)。运用凝集素标记血管内皮细胞以观察胎盘血管形态,体视学方法分析胎盘血管密度,实时荧光PCR检测胎盘血管因子VEGF-A、VEGFR1、VEGFR2、Tie2、Angpt1、Angpt2mRNA的表达,免疫组化及Westernblot检测VEGF-A、VEGFR2、Tie2、Angpt2蛋白的表达。结果 FGR组胎盘胎儿血管总体积为(45±21)mm3,显著小于正常组(70±19)mm3(P<0.05)。FGR组胎盘血液交换屏障厚度为(5.839±0.205)μm显著高于正常组(1.967±0.543)μm(P<0.05)。FGR组胎盘血管体积密度为(0.100±0.450)(0.032～0.158),正常组胎盘血管体积密度为(0.113±0.018)(0.086～0.135),两组间差异无统计学意义。与正常组相比,FGR组的VEGF-A mRNA表达显著下降(P<0.05),其它因子的mRNA表达较正常组微升高,但差异无统计学意义。FGR组的VEGF-A、VEGFR2、Tie2、An-gpt2蛋白表达有增加趋势,但差异无统计学意义。结论被动吸烟可使胎盘血管总体积显著减少、胎盘血液交换屏障厚度显著增加,导致胎盘营养交换功能不足,从而引发胎儿生长受限。但部分被动吸烟所诱导的FGR胎盘血管密度发生代偿性增加,以致FGR胎盘血管密度及血管因子mRNA、蛋白表达的改变不显著。

Objective To investigate the placental vascular abnormalities associated with fetal growth retardation（FGR）induced by passive smoking and the mechanism.Methods The animal FGR model was established by passive smoking.Twelve pregnant rats were randomly divided into normal group and FGR group.Three placentas were selected from each pregnant rat,so there were 18 samples in each group.The vessel was labeled with lectin and analyzed by stereological techniques.Real-time PCR was used to detect the mRNA expression of VEGF-A,VEGFR1,VEGFR2,Tie2,Angpt1 and Angpt2.The protein expression of VEGF-A,VEGFR2,Tie2 and Angpt2 was detected by using immunohistochemistry and Western blot.Results Total placental fetal vasculature was significantly decreased in FGR group[（45±21）mm3]as compared with normal group[（70±19）mm3].The exchange barrier was thicker in FGR group[（5.839±0.205）μm]than that in normal group[（1.967±0.543）μm].Fetal relative vascular density was[（0.113±0.018）,0.086-0.135]in normal group,and that was[（0.100±0.450）,0.032-0.158]in FGR group.There was no significant difference between two groups except enlarged range in FGR group.VEGF-A mRNA expression was significantly decreased in FGR group as compared with normal group,but there was no significant difference in the mRNA expression of the rest vascular factors except a small increase in FGR group.VEGF-A,VEGFR2,Tie2 and angpt2 protein expression tended to increase in FGR group as compared with normal group,but there was no significant difference.Conclusion Significantly decreased total placental fetal vasculature and significantly thicker exchange barrier caused by passive smoking could contribute to the insufficiency of placental nutrition exchange function and then cause FGR.However,vascular density increased for compensation occurred in some of FGR placentas induced by passive smoking,causing no significant changes in the placental vascular density and placental vascular factors mRNA and protein expression as compared with those of normal placentas.