同型半胱氨酸致细胞凋亡与畸胎发生的关系

为探讨胚胎细胞凋亡在同型半胱氨酸（ｈｏｍ ｏｃｙｓｔｅｉｎｅ， Ｈ Ｃ Ｙ）致胚胎神经管畸形和先天性心脏畸形中的作用，作者建立了２种鸡胚胎定位注射技术，观察 Ｈ Ｃ Ｙ 对６日龄胚胎的发育毒性。采用流式细胞仪、组织病理、透射电镜、原位末端标记、甲绿 派若宁双染 Ｄ Ｎ Ａ 和 Ｒ Ｎ Ａ 方法，探讨 Ｈ Ｃ Ｙ 激发细胞凋亡在畸胎发生中的作用。应用 Ｈ Ｐ Ｌ Ｃ法检测胚胎血浆总 Ｈ Ｃ Ｙ 水平的变化。结果不同位点微注射 Ｈ Ｃ Ｙ（４～８μｍ ｏｌ／胚胎）后，均可造成胚胎中枢神经系统和心脏畸形，但其所致后果不同。畸形的主要表现是异位心、心包积液、心内膜垫缺损、脑膨出、脑裂和小头等，其它表现还有体位异常、发育迟缓和死亡。 Ｈ Ｃ Ｙ 能明显干扰胚胎细胞周期，抑制胚胎细胞 Ｄ Ｎ Ａ 和 Ｒ Ｎ Ａ 的合成。在胚胎脑和心脏区域，观察到凋亡的神经细胞、心肌细胞及血管内皮细胞等，均明显高于正常组。发现 Ｈ Ｃ Ｙ 所致细胞线粒体的变异（例如：线粒体肿胀、气球样变、嵴损伤及电子密度增高等）与胚胎细胞凋亡关系密切。胚外膜滴注 Ｈ Ｃ Ｙ 后，胚胎血浆 Ｈ Ｃ Ｙ 在１２０分钟时达高峰值（８０５８μｍ ｏｌ／ Ｌ），显著高于正常对照组；同时滴注叶酸（５μｇ／胚胎）可明显?

Relationship between homocysteine|induced apoptosis and teratogenesis in developing avian embryo

It has been hypothesized that homocysteine(HCY) can induce apoptosis at the organogenesis-stage of chick embryos and which can be the relationship between HCY and congenital defects of neural tube and heart. Exogenous D, L-HCY (4-8 mumol/embryo) was injected into the place near brain and the yolk of the day 4 embryos. Then they were harvested 2 days later and examined by flow cytometry, histopathology, electronic microscope, in situ end labeling of DNA strand break and methylgreen-pyronine double staining. The change of plasma HCY level of day 10 embryos was also inspected by HPLC analysis. The HCY injected at different position of embryos could result in heart and neural tube defects, which included ectopia cardis, hydropericardium, endocardial cushion defect, encephalocele, microcephaly, abnormal flexions and so on. HCY could apparently disturb embryonic cell cycle, suppress the synthesis of DNA and RNA of embryonic cells. Excessive apoptotic cells in brain and heart were observed in HCY|treatment groups. It was discovered that mitochondrial damage could be described as an early event in cellular apoptosis of chick embryos. After 8 mumol of HCY was placed on the inner shell membrance, there was an obvious increase of plasma HCY concentration with a peak value of 80.58 mumol/L in 120 min, and followed by declining. On the other hand, 5 micrograms of folic acid given simultaneously with HCY could sharply curtail the rise in plasma HCY. It is concluded that HCY is a cytotoxin, inducing over apoptosis of embryos in some areas, which is coincident with the pathologic changes of neural system and heart. These findings show that there is a close relationship among HCY, apoptosis and birth defect in developing chick embryos. Mitochondrial dysmorphosis may be an important early event of apoptosis in embryos after exposure to HCY.