Neuropeptide Y in Multiple Endocrine Neoplasia: Release During Surgery for Phaeochromocytoma

Abstract

High plasma concentrations of neuropeptide Y (NPY) were found in a patient with bilateral adrenal phaeochromocytomas and medullary thyroid carcinoma associated with MEN IIa (32 pmol/l, normal less than 3.5 pmol/l). Both adrenal tumours contained and secreted NPY. Manipulation at operation produced a remarkable increase in plasma NPY concentrations (peak = 1631 pmol/l) coinciding with increases in plasma levels of catecholamines and arterial pressure. NPY was also shown to be present in thyroid tumour tissue: the concentration of NPY in tumour was 50-fold higher (0.9 nmol/g vs 0.004 nmol/g) than in adjacent normal thyroid tissue. It is possible that NPY from some phaeochromocytomas may contribute to hypertension during surgery.

Neuropeptide Y expression in phaeochromocytomas: relative absence in tumours from patients with von Hippel–Lindau syndrome

“…Variable tumour expression and plasma levels of the peptide have been suggested in other studies to contribute to differences in disease presentation, including presence of hypertension and left ventricular hypertrophy (Connell et al 1987, deS Senanayake et al 1995, Eurin et al 2000, Bravo 2002, Kuch-Wocial et al 2004. This possibility is supported by findings that the expression of NPY in phaeochromocytoma tumour tissue determines elevations in plasma levels of the peptide, which in some patients may reach 6 .…”

Heterogeneity of neuropeptide Y immunoreactivity in patients with pheochromocytoma: influence on the diagnostic power of measuring plasma NPY using antisera with different specificities

“…Our results are in accordance with those of previous studies (2,12,(15)(16)(17)(18)(19)(20) that showed the majority of pheochromocytoma tumours to contain high amounts of NPY (84% of 97 cases) with identical Chromato¬ graphie properties to synthetic NPY (2,(13)(14)(15)(16)20). Contrary to the findings obtained in tumours, the relationship between the results of the two RIAs in plasma was not constant and the Nto C-terminal NPY-LI ratio varied from 0.2 to 3.1.…”

“…Analysis of the literature also reveals a clear contrast between the 53.9% incidence of elevated plasma NPY levels in pheochromocytoma patients using "sandwich" IRMAs that recognize only intact NPY (16)(17)(18)40) and the 76.1% incidence found using traditional RIAs with polyclonal antibodies that may recognize NPY frag¬ ments (2,12,15,16,21,22). However, in our study the sensitivity of the C-terminally directed RIA was clearly better than that of the N-terminally directed RIA.…”

“…However, since the very high plasma NPY levels obtained during surgery may influence blood pressure and cardiac function (2,18,44) and since NPY-induced constriction of skeletal and coronary arteries is inhibited by certain Ca2+ channel blockers but not by adrenoreceptor antagonists (7,36,45,46), the preoperative identification of NPY-secreting individuals among pheochromocytoma patients may still be useful for the anaesthetic management of these. However, since the very high plasma NPY levels obtained during surgery may influence blood pressure and cardiac function (2,18,44) and since NPY-induced constriction of skeletal and coronary arteries is inhibited by certain Ca2+ channel blockers but not by adrenoreceptor antagonists (7,36,45,46), the preoperative identification of NPY-secreting individuals among pheochromocytoma patients may still be useful for the anaesthetic management of these.…”

“…Several studies have shown that pheochromocytomas may produce large amounts of NPY (2, [12][13][14][15][16][17][18][19][20], which are released into the circulation (2,17,18,21). Thus, NPY may contribute to the high blood pressure in pheochromocytoma patients and its measurement in plasma may help diagnose pheochromocytoma.…”