Comparison of urinary component levels in 4 strains of mice with different physiological characteristics

Changes in urinary component levels before, during and after reproduction were examined with 1H-nuclear magnetic resonance (NMR) in four strains of female mice with different mammary tumour potential and related characteristics (SHN, SLN, GR/A and C3H/He). Regardless of the variations in these changes among the strains, the urinary component levels reflected physiological changes during reproduction and some strain-specific characteristics. The urinary excretion of citrate, 2-oxoglutarate and lactate increased from the virginal stage to pregnancy and declined during lactation in all strains, indicating a marked change in sugar metabolism during reproduction. SHN and SLN, which are from the same basal stock, showed a similar pattern and the level, of several components were lower than those of GR/A and C3H/He. The levels of some lower components were compensated for by higher urine excretion. The levels of taurine and betaine, both essential for fetal and pup growth, increased at lactation in only GR/A, reflecting the poorer pup growth observed in this strain. Finally, the 1H-NMR method was useful to estimate not only the metabolic but also the physiological changes of the animals without invasion, pain or distress and would thus contribute to animal welfare in the animal experiments.