同型半胱氨酸诱发鸡胚神经管畸形及叶酸的保护作用  

Homocysteine induced Neural Tube Defects in Chick Embryos and Protection of Folic Acid

作　　者：李勇[1] 李竹[1] 陈星[1] 齐佩文[1] 汤健[1] 

机构地区：[1]北京医科大学中国妇婴保健中心

出　　处：《卫生研究》1998年第6期372-376,共5页Journal of Hygiene Research

基　　金：国家"863"计划资助

摘　　要：为了揭示同型半胱氨酸（ｈｏｍｏｃｙｓｔｅｉｎｅ，ＨＣＹ）是否能导致胚胎发生神经管畸形（ＮＴＤｓ）和可能的致畸机制及验证叶酸和ＶＢ１２的干预效果，本研究应用鸡胚致畸试验、扫描电镜观察、尼罗兰盐活体染色、原位ＤＮＡ片段末端标记、甲基绿—派若宁染色显示核酸法、叶酸和Ｂ１２干预实验等方法检测了用ＨＣＹ（０～１６μｍｏｌ／胚胎）的不同胚龄胚胎１２７４只。结果显示ＨＣＹ对神经胚形成期和器官形成期的胚胎均有显著的致畸性并呈剂量－反应关系（Ｐ＜０．０００１），鸡胚发生ＮＴＤｓ的主要表现是露脑，裂脑和脊柱裂。首次发现ＨＣＹ能诱发神经系统细胞凋亡过度，其部位与ＮＴＤｓ发生部位相吻合。ＨＣＹ能抑制卵黄囊血管分化；损伤羊膜组织及细胞超微结构，如微绒毛变短，胞膜上出现空洞样变等。注射５μｇ叶酸明显拮抗ＨＣＹ（８μｍｏｌ／胚胎）的致畸性，ＮＴＤｓ发生率由４３．５％降至０（Ｐ＜０．０５）；注射１μｇＶＢ１２不能明显保护胚胎（Ｐ＞０．０５）。本研究结果说明ＨＣＹ能诱导胚胎发生ＮＴＤｓ；细胞凋亡在ＮＴＤｓ发生过程中起重要作用；叶酸能有效地预防ＮＴＤｓ；To reveal whether homocysteine(HCY) will be able to induce neural tube defects (NTDs)and possible teratogenic mechanisms, and identify the interventional effects of folic acid and vitamin B 12 on HCY induced NTDs,1274 chick embryos treated with L. D HCY(0～16 μmol/embryo) were detected by the methods of teratogenic trial, scanning electron microscopy(SEM), Nile blue sulfate vital staining, TdT mediated dUTP nick end labeling(TUNEL) methylgreen pyronine special staining for showing nucleic acid, and interventional assay of folic acid and VB 12 in different developmental stage. Results showed that HCY could induce teratogenesis in chick neurulation and organogenetic period, in dose response relationship (P<0 0001). The main forms of NTDs were exencephaly, cranioschisis and spina bifida. It has been first found that HCY could target excessive apoptosis of cells of embryonic nervous system, which consists with the sites of embryos developing NTDs. HCY could inhibit chick yolk sac vessel formation and blood circulation, and damage amniotic membrane. Under SEM it was observed that HCY resulted in abnormal ultrastructures, for example cavernous damages, atrophied microvilli and so on. After the injection of 5μg/embryo folic acid, the teratogenicity of HCY (8μmol/embryo) was significantly antagonized, the occurrence rate of NTDs was down from 43 5% to 0(P<0 05). However, vitamin B 12 (1μg/embryo) did not obviously attenuate the teratogenicity of HCY in day 6 chick embryos. These data prove that HCY per se causes dymorphogenesis of the neural tube. Apoptosis may play an important role in the etiopathology of NTDs. Folic acid can effectively prevent from the homocysteine induced NTDS. Causes of homocyscine induced NTDs may result from interaction or combination of different mechanisms.

关 键 词：同型半胱氨酸 神经管畸形 胚胎 细胞凋亡 叶酸 

分 类 号：Q593.4[生物学—生物化学] Q593.2