MRI images of the adult male mice were acquired by subjecting anesthetized mice to an MRI scan using a vertical bore 9.4-T Bruker AVANCE 400WB imaging spectrometer (Bruker BioSpin, Rheinstetten, Germany). Animals were anesthetized with 3% and 1.5% isoflurane in air (2 L/min flow rate) for induction and maintenance, respectively. MRI images were obtained by using the FISP-3D protocol of Paravision software 5.0, by setting the following parameter values: Effective TE = 4.0 ms, TR = 8.0 ms, Flip angle = 15 degree, Average number = 5, Acquisition Matrix = 256 × 256 × 256, FOV = 25.6 × 25.6 × 25.6 mm. Manual measurements were made on the 3-dimensional (3D) MRI data to calculate total brain volume, hippocampus volume and lateral ventricle volume using the InsightITK-Snap software52. Regional volumetric changes were measured by voxel-based morphometry (VBM) using the Statistical Parametric Mapping (SPM) software package (http://www.fil.ion.ucl.ac.uk/spm/software/) for MATLAB (Mathworks, Natick, MA, USA) for pilot survey (data not shown).