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

A modifying effect of carotenoids on carcinogenesis induced by N-methyl-H'-nitro-N-nitrosoguanidine (MNNG) in the rumen was studied in four groups of rats weighing 100-120 g. A diet of the first group contained a highly carotenoid complex from wild rose fruits at a dose of 30 mg/kg 3 times weekly; MNNG was administered at a dose of 5 mg per animal by means of a gastric tube for two days. Administration of the drug was repeated within 5 days. Treatment with the carotenoid complex was carried out 2 months before the MNNG administration. Group 2 and 3 received only MNNG or the carotenoid complex, respectively; Group 4 served as intact control. Tumors were detected in 33 rats of 81 animals studied (40.7%) in Group 1 and in 53 rats of 74 animals (71.6%) of Group 2 (P < 0.01). The mean time of the tumors detection constituted 40.7 +/- 9.5 days in Group I and 68.7 +/- 0.3 days (P < 0.05) in Group 2. All the tumors detected were localized in the rumen and consisted of papillomas appeared mainly as multiple forms. The data obtained suggest that carotenoids exhibited the modifying effect on MNNG-induced carcinogenesis of the rat rumen.