Orthogonal Diffusion Measurements in the Mouse Hypothalamus by MRI Reveal Cerebral Activity in the Fed or Fasted States

Blanca Lizarbe¹, Ania Benitez¹, Pilar Lopez-Larrubia¹, Sebastian Cerdan¹

We investigate the functional mechanisms underlying hypothalamic activation by fasting using Diffusion Weighted MR Imaging. We used eight C57 mice, acquiring DWI from axial sections of the brain containing the hypothalamus, in three orthogonal directions, with increasing diffusion weightings (10≤b≤90 and 200≤b≤1200), from the same fed or fasted mouse. The data set was fitted to biexponential model yielding parameter values for the relative contributions of the fast (FDP, Dfast) and slow (SDP, Dslow) diffusion phases. Fasting induced, among other effects, a directional dependent increase in the relative contribution of SDP, compatible with neurocellular swelling during activation.