Antioxidant system and apoptosis in diabetes-induced embryonic malformation.

我们研究了依赖谷胱甘肽的抗氧化系统和细胞凋亡在糖尿病相关胚胎畸形中的作用。妊娠第11天产链脲霉素诱导的糖尿病大鼠胚胎畸形发生率（神经管检出率为21.5 vs.2.8%, p<0.001）和发育迟缓发生率明显高于正常母鼠。糖尿病大鼠离体胚胎细胞在第11天细胞内自由基的形成增加。妊娠第11天，糖尿病大鼠胚胎组织细胞内谷胱甘肽浓度明显低于正常大鼠。糖尿病大鼠胚胎中谷胱甘肽合成酶γ -谷氨酰半胱氨酸合成酶（γ - gcs）活性明显降低，与γ - gcs mRNA表达减少有关。正常大鼠胚胎第10天闭合神经管神经上皮细胞tunel阳性凋亡细胞较多，糖尿病大鼠凋亡细胞较少。在糖尿病大鼠最大致畸易感期（妊娠第6 ~ 11天）给予γ - gcs特异性抑制剂丁硫氨酸亚砜胺（BSO）可使GSH降低46.7%，并增加神经病变频率（62.1比21.1）。l 5%, p < 0.0)。给糖尿病大鼠注射谷胱甘肽酯，恢复胚胎中谷胱甘肽的浓度，减少自由基的形成，导致畸形发生正常化（1.9 vs.21.5%），并改善生长迟缓。在同一时期给另一组妊娠大鼠注射胰岛素，导致畸形发生完全正常化（4.3 vs.21.5%）和生长迟缓。我们的研究结果表明，谷胱甘肽的消耗和谷胱甘肽合成酶对氧化应激的反应性受损以及神经管形成过程中细胞凋亡浓度的降低是糖尿病胚胎畸形（神经管缺陷）发展的关键。

We investigated the role of glutathione-dependent antioxidant system and Apoptosis on diabetes-related embryonic malformations. Embryos from streptozotocin-induced diabetic rats on gestational days 11 showed a significantly high frequency of embryonic malformations (neural tube detect 21.5 vs.2.8%, p<0.001) and growth retardation compared with those of normal mothers. The formation of intracellular free oxygen radical species increased in isolated embryonic cells of diabetic rats on days 11. The concentration of intracellular GSH in embryonic tissues of diabetic pregnant rats on day 11 was significantly low compared with those of normal rats. The activity of gamma-glutamylcysteine synthetase (gamma-GCS), the rate limiting GSH synthesizing enzyme, in embryos of diabetic rat was significantly low, associated with reduced expression ofgamma-GCS mRNA.TUNEL-positive apoptotic cells in neuroepithelial cells of closing neural tube in embryo at day 10 were frequently found from normal rats, but few from diabetic rats. Administration of buthionine sulfoxamine (BSO), a specific inhibitor of gamma-GCS, during the period of maximal teratogenic susceptibility (6 to ll day of gestation) to diabetic rats reduced GSH by 46.7% and increased the frequency of neural lesions (62.1 vs. 2l.5%, p<0.0l). Administration of GSH ester to diabetic rats restored GSH concentration in the embryos and reduced the formation of free oxygen radicals leading to normalization of dysmorphogenesis (1.9 vs.21.5%) and improvement in growth retardation : Administration of insulin in another group of pregnant rats during the same period resulted in complete normalization of dysmorphogenesis (4.3 vs.21.5%) and growth retardation. Our results indicate that GSH depletion and impaired responsiveness of GSH-synthesizing enzyme to oxidative stress and decreased concentration of apotosis during neural tube formation are critical in development of embryonic malformations (neural tube defects) in diabetes.