Quantitative analytical mass spectrometry of endogenous neuropeptides in human pituitaries

This manuscript reviews state-of-the-art mass spectrometric (MS) methodology for the qualitative (amino acid sequence determination) and quantitative analysis of opioid neuropeptides in human pituitary tissue. Those analytical data are required for the elucidation of the basic molecular mechanisms involved in tumor formation and to test the hypothesis that metabolic defects in neuropeptidergic system processing is a contributing factor to human anterior pituitary tumor formation. Several different neuropeptide products that derive metabolically from the proenkephalin A and proopiomelanocortin (POMC) precursors have been analyzed separately and together in human pituitaries, including post-mortem controls and post-surgical tumors. The quantification, with optimal molecular specificity, of a peptide in a tissue is an important measurement because the amount of an endogenous peptide reflects the ratio of its synthesis to its degradation and thus, any defects in those processes may be reflected in the amount of a peptide.