MALDI-IMS.

MALDI-IMS was acquired in the Applied Imaging Mass Spectrometry Core/Service Center at Johns Hopkins using 10-μm coronal slices, approximately 3.5 mm from the posterior of the brain, from the brains of 24-h-fasted adult CPT2^lox/lox and CPT2^B−/− mice (6 months old). All slices to be compared were prepared on a single slide for simultaneous acquisition at 50-μm resolution using a Bruker Rapiflex MALDI-time of flight (TOF)/TOF instrument. The slides were sprayed with 5 mg/ml 4-chloro-alpha-cyanocinnamic acid with a 70% acetonitrile and 2% trifluoroacetic acid solution. Data were processed and heat map images were generated using SCiLS software (https://scils.de).