Mass spectrometric imaging of neuropeptides in decapod crustacean neuronal tissues

The emerging technology mass spectrometric imaging (MSI) provides an attractive opportunity to detect and probe the molecular content of tissues in an anatomical context. This powerful methodology has been applied extensively to the localization of proteins, peptides, pharmaceuticals, metabolites, lipids, and other biological and chemical compounds in tissues. Herein, we present a method developed specifically for mapping neuropeptides in crustacean neuronal tissues. Both cryostat tissue sectioning and whole-mount tissue blotting techniques are highlighted. Careful sample preparation is essential for obtaining sufficient analyte/matrix mixing while retaining the spatial localization of the neuropeptides. Several matrix application apparatus and techniques are described and compared. Furthermore, three-dimensional (3D) imaging has been developed to provide detailed information about the distribution of neuropeptides within 3D structure of a crustacean brain.