Strategy for NMR metabolomic analysis of urine in mouse models of obesity- from sample collection to interpretation of acquired data
Abstrakt
The mouse model of monosodium glutamate induced obesity was used to examine and consequently opti-mize the strategy for analysis of urine samples by NMR spectroscopy. A set of nineteen easily detectablemetabolites typical in obesity-related studies was selected.
The impact of urine collection protocol, choiceof1H NMR pulse sequence, and finally the impact of the normalization method on the detected concen-tration of selected metabolites were investigated. We demonstrated the crucial effect of food intake anddiurnal rhythms resulting in the choice of a 24-hour fasting collection protocol as the most convenient fortracking obesity-induced increased sensitivity to fasting.
It was shown that the Carr-Purcell-Meiboom-Gill (CPMG) experiment is a better alternative to one-dimensional nuclear Overhauser enhancementspectroscopy (1D-NOESY) for NMR analysis of mouse urine due to its ability to filter undesirable signalsof proteins naturally present in rodent urine. Normalization to total spectral area provided comparableoutcomes as did normalization to creatinine or probabilistic quotient normalization in the CPMG-basedmodel.
The optimized approach was found to be beneficial mainly for low abundant metabolites rarelymonitored due to their overlap by strong protein signals.