Dietary nucleosides and nucleotides do not affect tumor incidence but reduce amyloidosis incidence in B6C3F1 mice irradiated with californium-252

Abstract

Objective We investigated the effects of a dietary mixture of nucleosides and nucleotides (NS) on the systemic incidence rates of postirradiation carcinogenesis and non-neoplastic lesions in mice. Methods Five-week-old male B6C3F1 mice were fed AIN-76B Purified Diet supplemented with NS for 1 wk and 13 mo before and after irradiation of neutron with californium-252 ( 252Cf); specifically NS was added to the AIN-76B Purified Diet (without nucleotide) to obtain a final concentration of 0%, 0.5%, or 2.5% NS. A commercial stock diet was also given to mice, and half of the mice were irradiated. Both irradiated and non-irradiated mice were used for reference controls. Results The incidence of liver tumors in each NS group was lower than that in the reference control group ( P < 0.01), but there were no differences between the 0%, 0.5%, and 2.5% NS groups. In contrast, the incidence rate of mice with non-neoplastic lesions in the 0% NS group was significantly higher than the reference control group ( P < 0.05). This higher incidence of mice with non-neoplastic lesions was significantly decreased upon supplementation of the nucleotide-free diet with 0.5% or 2.5% NS ( P < 0.01 and P < 0.05, respectively). Of the non-neoplastic lesions observed, the incidence of amyloidosis was decreased significantly upon supplementation of the nucleotide-free diet with 0.5% NS ( P < 0.05). Conclusion Supplementation of a nucleotide-free diet with NS inhibits the development of non-neoplastic lesions, such as those associated with amyloidosis, without promoting the carcinogenesis induced by 252Cf irradiation.