IGFI不仅可直接刺激胎儿的神经系统、骨骼、血液系统和内分泌系统等的发育,还可通过改善胎盘功能,调节胎盘血流转运,增加胎盘对营养物质的摄取,从而促进胎儿生长[6]. 本研究结果表明正常妊娠组IGFI的表达阳性率均明显高于胚胎发育终止组,且母血中IGFI的含量在正常妊娠组也显著高于胚胎发育终止组,说明胚胎发育早期IGFI蛋白保持较高的表达不但与早期胚胎的正常发育密切相关,而且还是维护正常胚胎和胎盘的生长所必需. IGFII在细胞滋养层细胞的侵入、分化和胎盘形成过程中以自分泌方式发挥重要作用. 在妊娠的前3 mo,IGFII对早期合体滋养层增殖和(或)分化起自分泌调节作用,在孕6 wk左右,IGFII即随绒毛外合体滋养层渗透和侵入到母体蜕膜,提示IGFII可能在滋养层侵入中发挥调节作用[7]. Lpoez等[8]发现缺乏IGFII基因的裸鼠胎盘海绵体滋养层糖原合成与糖原细胞数量较正常组显著下降,提示IGFII在胎盘中可调控糖原合成及糖原细胞的量,是糖原合成的重要调节器; 人类IGFII作用与其相似,如胰岛素一样刺激葡萄糖在胎盘的转运及合成,对胎盘的形成与功能有显著影响,从而进一步影响胎儿的生长发育. 本研究结果表明正常妊娠组IGFII的表达阳性率均明显高于胚胎发育终止组,且母血中IGFII 的含量在正常妊娠组也显著高于胚胎发育终止组,说明胚胎发育早期IGFII蛋白保持较高的表达不但与早期胚胎的正常发育密切相关,而且是早期胚胎发育是重要调节因子之一.
Somi等[9]学者发现整个妊娠期间胎盘组织分泌的IGFII量是IGFI的近10倍,而我们的研究与此不一致,IGFI,IGFII分泌量结果相当. 提示在维持胎盘生长过程中,IGFI和IGFII作用相似,检测血中IGFI,IGFII的含量可能作为判断胚胎发育状况的一项客观生化指标,不仅可能用于胎儿在宫内发育是否正常的监测,也为应用外源性胰岛素样生长因子治疗流产、早产和胎儿宫内发育迟缓(IUGR)等妊娠疾病提供了理论依据.
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