抄録
Multiple blood sampling times over a short period are often required in preclinical studies. Bioanalytical methods typically use blood volumes that are too large for repeated sampling in mice. The objective of our study was to improve blood sampling and bioanalytical techniques, allowing multiple sampling of each mouse over the full duration of the study. Sixteen untreated CD1 mice were sampled for T4 levels (6 timepoints over 24 hr) on Days 9 and 50 and on Days 22 and 38. The blood collection site was the saphenous vein. Fifty microliters of blood/timepoint was collected using a heparinised capillary. The capillary was placed in a tube for centrifugation, and spun to separate the plasma. The sample processing was by solid phase extraction followed by mass spectroscopy. Overall, T4 plasma levels ranged from 9 to 69 ng/ml. The results indicate that a slight decrease in T4 concentrations appears at the beginning of the nocturnal cycle. Levels of T4 showed individual variation throughout the day, and inter-individual variations during the study. In conclusion, our laboratory has developed a successful approach to sampling blood in mice on multiple occasions over a 24-hour period combined with a bioanalytical method with volumes as low as 10 uL of plasma. The results indicated circadian variation in T4 levels in mice between age 6-13 weeks. This approach is in line with 3R principles and could reduce the number of animals utilized for bioanalysis in toxicology studies.
