NEU经胎盘诱发大鼠脑肿瘤时间和剂量的初步研究

目的 探讨亚硝基乙基脲（NEU）经胎盘诱发脑肿瘤动物模型的时间和剂量依赖性。方法 （1）取孕16dSD大鼠20只，随机分为4组。经腹腔内注射NEU，剂量分别为20mg／kg，40mg／kg，60mg／kg．80mg／kg；（2）孕12d、14d、16d、18d的SD大鼠各4只，分别经腹腔内注射NEU40mg／kg；（3）子代鼠出生后150d灌注同定取脑。组织切片行HE和GFAP染色，光镜观察。结果 NEU20mg／kg剂量组脑肿瘤诱发率明显低于其他三组（P〈0．05）；孕12d、16d组诱发率较高，孕14d、18d组较低（辟0．066），尚不能认为有统计学差异，但P值接近于检验水准，可适当增大样本含量做进一步研究。结论 经胎盘诱发脑肿瘤的诱发率在妊娠中晚期较高，但还受其他因素的影响，提示与孕酮水平有一定的关系。建议使用剂量40mg／kg，增加剂量对脑肿瘤的诱发率影响不大。

Study on the time and dosage dependence of rat brain neoplasms induced transplacentally with NEU

Objective To study time and dose dependence of animal models with brain neoplasms induced transplacentally with N-ethyl-N-nitrosourea (NEU). Methods (1) 20 16-day pregnant SD rats were randomized into 4 groups and injected with NEU transabdominally at the dose of 20 mg/kg, 40 mg/kg, 60 mg/kg, 80 mg/kg in each group; (2) 12-, 14-, 16-, 18-day pregnant SD rats were injected for establishing the animal model of brain neoplasms with single dose of NEU (40 mg/kg) transabdominally. Each group contains 4 pregnant rats; (3) Brain samples were obtained by paraformaldehyde perfusion from offsprings at 150 d after birth respectively; all samples were sliced, stained with HE or immunohistochemical GFAP and then observed under light microscope. Results (1) Different exposure dose; the neoplasm incidence was significantly lower in the 20 mg/kg group than in the other three groups (P<0.05). (2) Different exposure time to NEU; the neoplasm incidence was higher in groups exposed to NEU at their 12th and 16th pregnant day than at 14th and 18th pregnant day (P=0.066). It could not be regarded that there was significant difference in statistics, but could enlarge the number of samples and further study. Conclusion Middle and late pregnant period are the best exposure time to NEU for establishing the animal models with brain neoplasms induced transplacentally with NEU because of the higher incidence than any other periods, though it may be affected by other factors, such as progesterone. The exposure dose we recommend is 40 mg/kg, but the more dosage has little effect on the incidence of brain neoplasms.