Metabolic changes in the PPARα-null mouse. (a) 1H-NMR spectra showing the difference in glucose and glycogen concentration between 3 and 13 months for liver tissue extracts from PPARα-null mice. Each spectrum is the average of the five spectra obtained from all animals at that age. Key: red, 3 months; blue, 5 months; black, 11 months; green, 13 months. (b) Principal components analysis (PCA) plot showing the clustering of 3-month (open circles), 5-month (open diamonds), 7-month (stars), 9-month (open triangles), 11-month (black squares) and 13-month (crosses) liver tissue across principal component 1. (c) Partial least squares plot regressing age of animal (y-axis) against the metabolic profile of the liver tissue (x-axis) in control mice as measured by 1H NMR spectroscopy. PPARα-null mice were then mapped on to the same model. Error bars indicate standard error. Reproduced from  with permission.