绿茶对甲基硝基亚硝基胍诱发LACA小鼠肺癌及癌前病变的预防作用

Preventive Effect of Green Tea on MNNG--induced Lung Cancers and Precancerous tesions in LACA Mice

实验先后两批,共取LACA小鼠390只。每批随机分为正对照、绿茶、复合及空白对照4组。正对照组和复合组每5天于小鼠尾静脉注射MNNG250μg一次,共7次,总量1.75mg;绿茶组和复合组每日用5％绿茶末普通饲料长期喂养,正对照组和空白对照组长期喂饲普通饲料。两批实验分别经96.4周及10 6周结束。结果绿茶不仅使肺发癌率从79.75％下降到13.59％,而且改变了肺肿瘤良、恶性及病理类型构成比,恶性肿瘤和癌前病变减少,对MNNG诱发小鼠肺癌及癌前病变可产生不同程度的预防作用。实验结果重复性好。

Three hundred and ninetyLACA mices of seven weeks old were usedin 2 batches (96.4 wks and 106 wks) forstudying the preventive effect of greentea on MNNG--induced lung cancers andprecancerous lesions. These mice (withineach batch) were randomly allocated tofour groups, namely, positive control (MNNG), green tea (GT), complex(MNNG+GT), and blank control (C)group. In MNNG group, MNNG 250μg) wasinjected intravenously every five days forseven times in each mouse; the totaldosage of MNNG was 1.75mg. In GTgroup, according to W/W, 5% GT dustwas well mixed into 95% common dietfor long-term breeding.In complex group.MNNG was given as that in MNNG groupand the mice were reared as those in GTgroup. The mice in MNNG group and in Cgroup were all reared by common diet.The mean amount of daily intake of feedwas 10g. The number of effective animalswas 354. The results of experiments showeddifferent degrees of preventive effect ofgreen tea on MNNG-induced lung cancersand precancerous lesions in LACA mice.Green tea exerted an effect on the numberof induced cancers and precancerous le-sions, causing a drop of the cancerous ratefrom 79.75% to 13.59% and the number oflung tumor down to 1/7-1/16 that of theMNNG group, i.e. down to less than onetumor nodule per mouse. It also alteredthe proportional rate of the kinds andpathological types of tumor, causing anincrease of tumor--free and Cancer--freeanimals by 67.33%(from 15. 19% up to 82.52%)and 66.16%(from 20.25% up to 86.41%)res-pectively, and denoting a decrease inmalignancy (adenoma with malignantchange, and malignant adenoma) from96.42% to 81.13%; there was no adenocar-cinoma in the complex group. In addition.green tea decreased the adenomatoidhyperplasia and dispelled the atypia oflung. The results of experiments showedgood duplication and absence of adversereactions to green tea.