[The effect of carotenoids on rat stomach carcinogenesis, induced by N-methyl-N'-nitro-N-nitrosoguanidine].

The effect of natural carotenoids on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitroguanidine (MNNG) was studied in 4 groups containing 105 rats. Highly carotenoid complex from wild rose fruits was added to drinking water of Group 1 (30 rats) at a dose of 15 mg/kg (as calculated per beta-carotene) 3 times weekly; as well as MNNG was present in water (0.01%). The carotenoid complex was supplemented to the ration 2 months before MNNG treatment and was continued within 15 months; MNNG treatment occurred within 6 months. Group 2 (30 rats) and Group 3 (30 rats) were treated with MNNG and the carotinoid complex, respectively; the 4 group (15 rats) was used as an intact control. Tumors were detected in 16 rats of 28 animals studied in Group 1 (57.1%) and in 11 rats of 25 animals in Group 2 (44%) (P < 0.05); malignization was found in the stomach and small intestine. The rate of involvement with gastric tumor in Group 1 was 3-fold higher as compared with those in the only MNNG treated animals--50% and 16%, respectively (P < 0.01). Tumors of the small intestine were detected in 5 rats of Group 1 (17.8%) and in 9 rats of Group 2 (36.6%); differences were statistically insignificant. However, carcinogenesis tended to accelerate. The mean time of stomach and small intestine tumor detection in Group 1 was equal to 286 and 276 +/- 46 days, respectively, and in Group 2--339.7 +/- 25.4 and 350.7 +/- 25.4 days, respectively (differences are insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)