Probing Neuronal Communication Via Novel Mass Spectral Strategies

Neuropeptides make up the largest and the most complex signaling molecules used in intercellular communication. Because of critical roles that these polypeptides play in the regulation of many physiological processes, it is of great interest to characterize these diverse assortments of chemical messengers and determine their functions in the neural circuitry. The simpler and well-characterized crustacean nervous system provides an excellent model system to facilitate analytical method development and to investigate how a rich repertoire of neuropeptides can fine tune a well-defined neural circuit that produces multiple outputs at the cellular and network levels. Using a highly sensitive mass spectrometry-based peptide profiling and de novo sequencing strategy, a large number of novel peptides have been discovered, revealing that even a relatively simple neural network contains an unexpectedly-rich diversity of neuropeptides¹. Furthermore, both mass spectrometric imaging techniques² and in vivo microdialysis sampling tools³ have been implemented to follow neuropeptide distribution and secretion in unprecedented details. Towards the goal of functional discovery of bioactive neuropeptides, novel quantitative schemes based on isotopic formaldehyde labeling and multiplexed isobaric labeling based on N,N-dimethylated leucine⁴ have been developed to produce differential display of neuropeptidomes under different physiological conditions⁵. Examples of neuropeptide regulation of feeding behavior and environmental stress will be described in this presentation. Collectively, these combined peptidomic and physiological studies will help to elucidate the functional roles that neuropeptides play in regulating neural network plasticity.