Diet is not responsible for the presence of several oxidatively damaged DNA lesions in mouse urine.

In order to eliminate the possibility that diet may influence urinary oxidative DNA lesion levels, in our experiments we used a recently developed technique involving HPLC pre-purification followed by gas chromatography with isotope dilution mass spectrometric detection. This methodology was applied for the determination of the lesions: 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and 5-(hydroxymethyl)uracil (5HMUra) in the urine of mice fed with nucleic acid free diet and normal, unrestricted diet. The mean levels of 8-oxoGua, 8-oxodGuo and 5HMUra of the animals fed the normal diet reached the mean values of 15.6 +/- 3.5, 2.0 +/- 0.53 and 16.8 +/- 10.4 nmol/kg/24 h, After feeding the mice for 12 days with nucleic acid free diet the respective values were 18.8 +/- 4.6, 1.6 +/- 0.3 and 25.4 +/- 10.5 nmol/kg/24 h, respectively. The results clearly demonstrate that irrespective of the diet, the excretion rates were not statistically different during the course of feeding. The respective p values for the differences between lesions in the two types of diets were: 0.13 (8-oxoGua), 0.16 (8-oxodGuo), 0.18 (5-HMUra). Our results clearly indicate that diet does not contribute to urinary excretion of the lesions in mouse model.