Urinary excretion of uric acid, allantoin, and 8-OH-Deoxyguanosine in uricase-knockout mice

Although uricase-knockout (Uox KO) mice are reported to develop uric acid (UA) nephropathy, those that mature without severe nephropathy could be useful for research into purine metabolism in humans. In this study, we measured the urinary excretion of creatinine, UA, allantoin, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) collected from Uox KO mice housed in metabolic cages. UA and allantoin were determined using liquid chromatography-mass spectrometry and creatinine and 8-OHdG were measured with a commercial kit. Uox KO mice excreted significantly higher levels of UA than wild-typemice (C57BL/6), while the excretion of allantoin was significantly lower. Urinary allantoin was detected in Uox KO mice despite a lack of uricase, which is the same as in humans. In contrast to the elevated levels of UA, the daily excretion of 8-OHdG, an oxidative stress marker, was lower in Uox KO mice. UA is thought to act as an anti-oxidizing agent in humans; thus, these results show that Uox KO mice are potential animal models for research into human purine metabolism.