砷诱发细胞凋亡与大鼠畸胎形成的关系研究

为进一步揭示砷的致畸性、胚胎毒性和作用机制，采用胚胎活体染色和原位ＤＮＡ末端标记等技术探讨了不同剂量砷是否能诱导孕９．５天龄大鼠的胚胎细胞发生凋亡（程序性细胞死亡）及其凋亡与畸胎形成的关系。结果表明随着砷浓度（０、１、４和８ｍｇ／ｋｇ）的增高，畸胎率和死胎率分别由２．６％和０上升到３５．７％和２３．８％，呈明显剂量－反应关系。活体染色发现在胚胎脑、眼、体节、肢芽和腮弓等部位出现大量散在的凋亡细胞，与畸形发生部位相一致。原位ＤＮＡ末端标记进一步证实砷能诱发器官形成期胚胎细胞凋亡，８ｍｇ／ｋｇ砷染毒后，凋亡阳性率高达５５．６％（Ｐ＜０．０５），表明凋亡与畸胎发生关系密切，这是砷致畸作用的重要机制之一。实验结果还发现胚胎细胞坏死亦与畸胎形成有关。

Role of Programmed Cell Death in Mediating Arsenic Induced Rat Embryo Anomalies

With a view to further investigating teratogenicity, embryotoxicity and teratogenic mechanism of arsenic on developing embryos, the relationship between apoptosis (programmed cell death, PCD) and arsenic-induced teratogenesis was studied during head-fold stage by using in situ 3'end-labeling of DNA and Nile blue sulfate (NBS) vital staining. Sprague-Dawley rats were intraperitoneally injected on gestation day 9.5 with doses of 0, 1, 4 and 8 mg/kg arsenic respectively, and killed at day 12, the results show that teratogenic incidence and mortality increased to 35.7% and 23.8% respectively, in apparent dose-effect relationship. In NBS staining experience, it was found that arsenic induced PCD in many areas, which related with abnormal development of brain, optic system, somite segmentation, limb bud and so on. In situ 3' end-labeling of DNA further supported above-mentioned results. The positive rate of apoptotic cell death was up to 55.6% (P < 0.05). This research suggested a positive correlation between abnormal PCD and teratogenesis. It may be seen that over-apoptosis is one of teratogenic mechanisms of arsenic. Moreover, our results show that necrosis plays some role in teratogenesis as well.