Prevention of spontaneous and chemically induced carcinogenesis using activated carbon fiber adsorbent. III. Inhibitory effect of the activated carbon fiber adsorbent 'Aqualen' on 1,2-dimethylhydrazine-induced intestinal carcinogenesis in rats

Two-month-old outbred female LIO rats were exposed weekly to 15 (experiment I, groups 1, 2 and 3) or to 5 (experiment II, groups 4, 5 and 6) subcutane ous injections of 1,2-dimethylhydrazine (DMH) at a single dose of 21 mg/kg of body weight. From the day of the first injection of the carcinogen, the rats from groups 2, 3, 5 and 6 were given Aqualen(R) in their diet. In both experiments rats were fed Aqualen five times per week together with lab ch ow at the daily dose of 0.1 g/kg (groups 2 and 5) or 1.0 g/kg (groups 3 and 6) of body weight, Additionally, other rats were not exposed to the carcin ogen and served as an intact control (group 7) or were given Aqualen with t he diet at the daily dose of 0.1 g/kg (group 8) or 1.0 g/kg (group 9). Thes e experiments were finalized 6 months after the first injection of DMH. In experiments I and II, the majority of tumors were localized in the descendi ng colon, Tumors of the small intestines developed only in rats from experi ment I. The total incidence of colon tumors as well as tumors in different parts of the colon and the mean number of tumors per rat were much higher i n rats from all groups in experiment I than in the rats from experiment II. In experiment I supplementation of Aqualen to the diet was followed by a d ecrease in the incidence of tumors in the ascending colon and by a decrease in the number of tumors per rat in both ascending and descending colons re gardless of the dose of the enterosorbent. In experiment IT the effect of A qualen was stronger than in experiment I - the enterosorbent decreased both the tumor incidence and the multiplicity in the total colon, its ascending and descending parts and in the rectum. In experiments I and II the percen tage of small colon tumors among rats exposed to Aqualen (groups 2, 3, 5 an d 6) was higher than that of the controls (groups 1 and 4). Most of detecte d intestinal tumors were classified as adenocarcinomas. The level of tumor differentiation was higher in rats exposed to Aqualen. There were no pathol ogical changes observed in rats exposed to Aqualen without DMH. Carcinogen treatment resulted in an increase of serum glucose and cholesterol levels w hereas Aqualen normalized these changes. Thus, our results demonstrate the inhibitory effect of activated carbon fiber adsorbent Aqualen on intestinal carcinogenesis in rats. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.