An Experimental Study Of Passive Smoking-induced Teratogenesis

It is apparent that smoking is harmful to human health, the amount of smoking women in china is far less than western countries, however, the number of smoking men and passive smoking women in china is enormous, therefore, the hazard on fetus of smoking draws more and more concern. A multitude of clinical research of and animal experiments demonstrate tha smoking can cause defect of neural system and urinary system and is correlated with spontaneous abortion, death fetus and perinatal mortality.At present the research of smoking-induced terategenesi s confine to clinical and epidemic investigation and the effect of smoking on development of neural tube is merely studied Therefore, we design the animal model of smoking-induced teratogensis to discover the effect of smoking on apoptosis and the expression of apoptosis-assoc iated genes Bcl-2 and Bax in the neural epithelium of embryos. It can provide theorical basis and experimental evidence for research of mechanism of smoking-induced terato genesis and study of anti-terato gensi s .Pregnant golden hamsters were given different doses (4 hours per day; 6 hours per day) on different gestation day ( GD3-5 GD6-8, GD9-1 1).After examining and statistically analysising the result, we choose our animal model in which smoking can cause highest teratogenic rate and lowest resorption rate.On the basis of the animal model, the light microscope isemployed to observe the histological alteration during the differentiation time of the neural tube. With the TEM and in situ TUNEL technology, the apoptosis phenomena and its histological and quantitative alteration were studied on the neural tube of the experimental and control embryos.In order to explore the molecular mechanism of the excessive apoptosis caused by passive smoking, the immunohistochemica method and image analysis technology were employed to study the quality, quantity and distribution changes on the expression of apoptosis-associated genes Bcl-2 and Bax in the neura epithelium of experimental embryos.The result were as follows:1. Passive smoking has significant embryotoxic effects and is relative to the quantity of smoking, when smoking for 6 hours per day in successive 3 days, the resorption and death rate and teratagenisis rate reach peak, the weight of live fetus is lower compared with that of treatment of smoking.2. The embryotoxic effects of passive smoking is correlated to the treatment time, the teratogenic incidence of golden hamster reaches peak after smoking during GD6-8, it is the idea golden hamster model of smoking-induced teraogenesis.3. Smoking can cause excessive apoptosis in neural tube of experimental group, more apoptosis cells were observed in neural epithelium compared with the control group.4. The Bcl-2 and Bax genes were extensively expressed in the neuroepithelial cell. After it is treated with smoking, the expression of the Bcl-2 declines in the experimental groups onneural epithelial cells, compared with the control groups, the expression of Bax increases.Conclusion:1.As a teratogen, smoking has significant embryotoxic effects and teratogenic effects, and these effects are significantly relative to the dose and the treatment time of the smoking.2. On this golden hamster model of smoking-induc ed teratogenesi s, the teratogenic incidence is higher. It is easily operated and repeated, and therefore has higher value of experimentation.3. One mechanism of the smoking-induced neural tube defec is that smoking can cause excessive apoptosis on the neura epithelium.4. Smoking can decrease the expression of Bcl-2 and augmen the expression of Bax, the coordination of which could cause excessive apoptosis of the neural epithelial cell.