Integrated data from intravital imaging and HPLC-MS/MS analysis reveal large interspecies differences in AFB₁ metabolism in mice and rats

Large interspecies differences between rats and mice concerning the hepatotoxicity and carcinogenicity of aflatoxin B-1 (AFB(1)) are known, with mice being more resistant. However, a comprehensive interspecies comparison including subcellular liver tissue compartments has not yet been performed. In this study, we performed spatio-temporal intravital analysis of AFB(1) kinetics in the livers of anesthetized mice and rats. This was supported by time-dependent analysis of the parent compound as well as metabolites and adducts in blood, urine, and bile of both species by HPLC-MS/MS. The integrated data from intravital imaging and HPLC-MS/MS analysis revealed major interspecies differences between rats and mice: (1) AFB(1)-associated fluorescence persisted much longer in the nuclei of rat than mouse hepatocytes; (2) in the sinusoidal blood, AFB(1)-associated fluorescence was rapidly cleared in mice, while a time-dependent increase was observed in rats in the first three hours after injection followed by a plateau that lasted until the end of the observation period of six hours; (3) this coincided with a far stronger increase of AFB(1)-lysine adducts in the blood of rats compared to mice; (4) the AFB(1)-guanine adduct was detected at much higher concentrations in bile and urine of rats than mice. In both species, the AFB(1)-glutathione conjugate was efficiently excreted via bile, where it reached concentrations at least three orders of magnitude higher compared to blood. In conclusion, major differences between mice and rats were observed, concerning the nuclear persistence, formation of AFB(1)-lysine adducts, and the AFB(1)-guanine adducts.