Characterization of neurotensin-like immunoreactivity in human cerebrospinal fluid by high-performance liquid chromatography combined with mass spectrometry

Localization of neuropeptides by radioimmunoassay

The past half-century has seen an enormous development in the area of biomedical science. This includes also research related to neuroactive peptides. These compounds have been the subject for extensive studies in many cases resulting in knowledge opening for new therapeutic strategies for the management of various neurological disorders. In this research the radioimmunoassay has represented an invaluable tool. This method, first introduced for the assessment of serum and plasma levels of various hormones, meant a transition from bioassay to a more sensitive and precise technique for protein and peptide quantification in samples of clinical relevance. It accounts for an approach which became one of the most widely used methods in routine and research at many clinical and basic laboratories. This relatively simple technique also became a worthwhile instrument in most studies exploring the field of neuropeptides. In this chapter, various approaches to probe neuroactive peptides in tissues and biological fluids are reviewed. It is by no means exhaustive and does cover all aspects of radioimmunoassay, but it serves to give the readers an idea about some essential principles of the practical use of this technique for probing peptides in the above-mentioned compartments.

Reversed-phase high-performance liquid chromatography combined with tandem mass spectrometry in studies of a substance P-converting enzyme from human cerebrospinal fluid

The application of reversed-phase HPLC in combination with micro-electrospray mass spectrometry to study a substance P (SP)-hydrolysing endoprotease in human cerebrospinal fluid (hCSF) is reported. The enzyme was partially purified from the hCSF specimens by ion-exchange chromatography and molecular sieving. During the purification procedure the enzyme activity was monitored by measuring the formation of the SP-fragment 1-7 from SP by radioimmunoassay. Regarding its behaviour upon molecular sieve chromatography, the enzyme was suggested to be associated with an apparent molecular mass of around 100 x 10(3). In subsequent experiments using the partially purified endopeptidase, the hydrolysis of SP was demonstrated by HPLC. The reaction product mixture was resolved in several components including the N-terminal fragments 1-8, 1-7 and 1-6 and the C-terminal fragment 8-11. The identity of these fragments were confirmed by tandem mass spectrometry. It was concluded that the present SP-degrading enzyme is different from those previously identified and purified from hCSF. The applied techniques were proven to be highly efficient for the recovery and identification of the released peptide products.

Neurotensin-mediated effects on astrocytic tumor cell proliferation

Neurotensin (NT) and neurotensin receptors (NTRs) are widely found in the brain, NT may be considered as a mitogen factor in some tissues. However, no NT-mediated effects on glioma cell proliferation have been reported so far. In our present study we investigated the influence of NT on the proliferation of astrocytic tumor cell lines. To this end we used a synthetic NT agonist (JMV-449), a protease inhibitor which blocks the natural degradation of NT (JMV-531), and NT. The in vitro biological models used in the present study included the low grade SW1088, and the high grade U87, U373 and A172 astrocytic tumor cell lines. The peptide-induced influence on astrocytic tumor cell proliferation was investigated by means of the colorimetric MTT assay. Our results show that the NT and the NT agonist significantly stimulated the proliferation in 2/4 and 3/4 of the astrocytic cell lines respectively. Similarly, compound JMV-531 also induced an increase in the proliferation of 2/4 of the astrocytic cell lines. This marked influence of the NT and NT agonists, or the enzyme-endogenous prevention of its degradation on the regulation of astrocytic tumor growth therefore suggests that NT antagonists might be used to treat certain patients with high grade astrocytic tumors that do not respond to chemotherapy and/or radiotherapy.