Abstract

Cancer of the liver is the fourth most prevalent (4.75%) of all malignant tumors among Koreans, whereas in the United States and Europe, the prevalence is about 0.2 to 0.7%. Both aflatoxin and dimethylaminoazobenzene are widely used as the hepatoma- inducing agents in laboratory animals. Epidemiologic studies show correlation between the incidence of hepatoma in specific locales and the apparent content of aflatoxin in diet (Alpert et al., 1968, 1969). Kim et al. detected aflatoxin B1 B2 G1 and G2 in Meju and Doenjang, both of which are Korean-style foodstuffs, the former is a naturally inoculated soybean substrate for soy sauce and paste fermentation, and the latter is a Korean style fermented soybean paste. We made an attempt to observe the difference between the incidence of hyperplastic nodules and the mode of tumor growth in the liver of rats, which were administered aflatoxin B1(APB1) and p-dimethylaminoazobenzene (DAB) by means of intubation into the stomach, and the effect of partial hepatectomy on them. Male Sprague-Dawley rats, 180 to 220 gm. in weight were used exclusively. Each animal received 37.5㎍ of aflatoxin B1 or 5 ㎎ of p-dimethylaminoazo- benzene in 40 doses over 8 weeks. Partial hepatectomy was performed after feeding for 6 weeks and consisted of the anterior median lobe. The increase of body weight, the incidence and site of hyperplastic nodules, and the rates of liver regeneration after partial hepatectomy, were observed 2, 4, 6, 8, 10, 12, 14 and 18 weeks after the initiation of carcinogen-feeding. The result were as follows: 1. The increase of body weight of the rats which received carcinogens (AFB1 and DAB) was delayed in comparison with that of normal rats and that of the partially hepatectomized rats which received carcinogens was also delayed for the first 2 weeks and thereafter accelerated in comparison with that of the rats which received only carcinogens. 2. Carcinogens (AFB1 and DAB) inhibited the regeneration of the liver following partial hepatectomy. 3. The incidence of hyperplastic nodule of the liver in rats which received AFB1 was higher than that of the rats which received DAB, and partial hepatectomy seemed to be the cause of the formation of hyperplastic nodules in AFB1 group.