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目的观察孕早期不同剂量氯乙烯(VC)染毒后胎鼠神经系统发育以及神经上皮细胞增殖和凋亡的变化情况,明确VC对神经系统发育的致畸作用。方法将孕鼠21只按完全随机设计分组法分为实验组和对照组,实验组分别用不同剂量的VC对孕6.5 d的小鼠进行腹腔染毒,对照组注射花生油,均于E12.5取胚胎。观察胎鼠的表观发育情况,计算胚胎畸形率以及神经系统异常的发生率。运用PCNA免疫组织化学技术和TUNEL染色技术检测并观察神经管上皮细胞的增殖及其凋亡的变化。结果①中剂量VC组胎鼠活胎率下降,活胎中畸胎发生率高达51%,其中神经管畸形发生率占40%,与正常对照组相比差异有统计学意义(P<0.05);高剂量VC组胎鼠活胎率仅占55%,活胎中畸胎率明显增高占71%,其中神经管畸形发生率占50%,与正常对照组相比差异有统计学意义(P<0.01)。②中剂量和高剂量VC组胚胎神经管上皮厚薄不一致;高剂量组神经管多数呈明显未闭合状,神经管周围的间充质细胞肿胀,轮廓不清。③正常小鼠神经管神经上皮内可见PCNA阳性细胞与TUNEL阳性细胞分布;实验组各型阳性细胞分布与对照组相似,但随着染毒剂量的增加,PCNA阳性细胞表达减少,而TUNEL阳性细胞表达增多。结论孕早期一定剂量氯乙烯染毒可导致胚胎畸形率升高,神经管畸形率也相应上升。氯乙烯主要可抑制神经上皮细胞的增殖,诱导细胞凋亡发生增多,导致增殖与凋亡比例失调。
Objective To observe the changes of neural system and neuroepithelial cell proliferation and apoptosis after exposure to different doses of VC in early pregnancy and to clarify the teratogenic effects of VC on nervous system development. Methods Twenty-one pregnant rats were randomly divided into experimental group and control group. Experimental groups were given intraperitoneal injection of VC at different doses of VC for gestational 6.5 days, while those in control group were injected with peanut oil at E12.5 Take the embryo. Observe the apparent development of fetal rat embryo malformation rate and the incidence of abnormalities in the nervous system. PCNA immunohistochemistry and TUNEL staining were used to detect and observe the changes of neural tube epithelial cells proliferation and apoptosis. Results ① The rate of live fetus in middle dose VC group was decreased, the rate of teratogenesis in live fetus was as high as 51%, and the incidence of neural tube defects was 40%, which was significantly different from that of normal control group (P <0.05) ; The percentage of live fetus in high-dose VC group was only 55%, the rate of teratogenic rate in live fetus was 71%, and the incidence of neural tube defects was 50%, which was significantly different from that of normal control group (P <0.01). (2) The neural tube epithelial thickness of embryos in medium dose and high dose VC groups was inconsistent. The majority of neural tube in high dose group showed obvious unclosed and the mesenchymal cells around neural tube had swollen and the outline was unclear. (3) The distribution of PCNA positive cells and TUNEL positive cells in the neural tube epithelial cells of normal mice was similar. The distribution of positive cells in the experimental group was similar to that in the control group. However, the expression of PCNA positive cells decreased with the increase of the dose of TUNEL positive cells Increased expression. Conclusion Exposure to a certain dose of vinyl chloride during early pregnancy leads to an increase in embryo malformation rate and a corresponding increase in the rate of neural tube defects. Vinyl chloride can mainly inhibit the proliferation of neuroepithelial cells, induced apoptosis increased, resulting in an imbalance between proliferation and apoptosis.