Neuropeptides of the islets of Langerhans: a peptidomics study.

Neuropeptides from the endocrine pancreas (the islets of Langerhans) play an important role in the regulation of blood glucose levels. Therefore, our aim is to identify the "peptidome" (the in vivo peptide profile at a certain time) of the pancreatic islets, which is beneficial for medical progress related to the treatment of diabetes. So far, there are few neuropeptides isolated and sequenced from the endocrine pancreas and mainly in situ hybridisation and immunocytochemical techniques have been used to demonstrate the occurrence of peptides in the pancreas. These techniques do not allow for unequivocal identification of peptides. In contrary, mass spectrometry identifies peptides unambiguously. We have analysed the peptidome of the islets using peptidomics, i.e. a combination of liquid chromatography, mass spectrometry and bioinformatics. We are able to identify the peptidome of islets extracts. We not only confirm the presence of peptides with a well-known effect on blood glucose levels, but also identify new peptides, which are unknown to affect blood glucose levels.