Neuropeptide Expression Patterns as Determined by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

The diversity of neuropeptide transmitters is fairly large, as compared to other, “classical” neurotransmitters, such as acetylcholine and glutamate. Currently, immunocytochemistry and in situ hybridization are the methods of choice to map neuropeptide expression patterns in the nervous system. A disadvantage of these methods, however, is that they give limited clues to the structural identities of processed and biologically active peptides contained in the cells. Moreover, these techniques do not reveal previously undescribed cotransmitters.