Mass spectrometric analysis of molluscan neuropeptides

The central nervous systems of molluscan species contain high levels of structurally diverse peptides that function as neurotransmitters, neuromodulators or neurohormones. Peptide diversity is believed to be a way to increase the information handling capacity of neurons in the context of a brain with low cell numbers and neuronal connectivity. Accordingly, much effort has been made to identify peptides from single neurons and tissues of interest. In the past decade a mass spectrometry-based approach has been applied to detect and characterize peptides from single neurons, nerves and tissues of the molluscan brain. Peptides from single neurons are often analysed directly by mass spectrometry without prior sample preparation. Single neurons from the molluscan brain may be identified based on their position, cell morphology and colour. Neurons that cannot be readily identified can be tagged functionally or chemically. For the analysis of peptides from tissues, special extraction methods in conjunction with peptide separation by liquid chromatography coupled to mass spectrometry have been developed. Tens to hundreds of peptides from the tissue extract can be detected and characterized in a single analysis.