Fig. 2

HFD-fed mice showed increased lactate signal and decreased brain perfusion in hyperpolarized ¹³C magnetic resonance (MR) spectroscopy. A, B, The stack plot of sequential spectra collected every second displayed for 90 s of the hyperpolarized ¹³C MR spectrum shows [1-¹³C] pyruvate at 173 ppm and [1-¹³C] lactate at 185 ppm in the brain of control (a) and HFD-fed mice (b). (c) The dynamic conversion ratio of hyperpolarized [1-¹³C] pyruvate/[1-¹³C]lactate calculated from the dynamic peak intensities (p < .0001). Shaded regions represent standard error of the mean value (n = 5 for both groups). (d) The box plot shows the total hyperpolarized ¹³C signal from the brain obtained for 10 s after the injection (P < .01). (e) Hyperpolarized [1-¹³C]lactate/[1-¹³C]pyruvate ratio showed a negative correlation with total ¹³C signal (n = 10, Pearson’s r = − 0.632, P < .05). (f) The ratio of [1-¹³C] lactate/¹³C-bicarbonate calculated from the peak intensity (n = 5 for both groups). Error bars represent standard error of the mean. * p < 0.05