Monoamine oxidase A down-regulation contributes to high metanephrine concentration in pheochromocytoma

The Journal of Clinical Endocrinology and Metabolism
Eric GrouzmannKarim Abid

Abstract

The high diagnostic performance of plasma-free metanephrines (metanephrine and normetanephrine) (MN) for pheochromocytoma (PHEO) results from the tumoral expression of catechol-O-methyltransferase (COMT), the enzyme involved in O-methylation of catecholamines (CAT). Intriguingly, metanephrine, in contrast to epinephrine, is not remarkably secreted during a stress in hypertensive or normotensive subjects, whereas in PHEO patients CAT and MN are both raised to high levels. Because epinephrine and metanephrine are almost exclusively produced by the adrenal medulla, this suggests distinct CAT metabolism in chromaffin cells and pheochromocytes. The objective of the study was to compare CAT metabolism between adrenal medulla and PHEO tissue regarding related enzyme expression including monoamine oxidases (MAO) and COMT. A multicenter comparative study was conducted. The study included 21 patients with a histologically confirmed PHEO and eight adrenal glands as control. CAT, dihydroxyphenol-glycol, 3,4-dihydroxyphenylacetic acid, and MN were measured in adrenal medulla and PHEO tissue. Western blot, quantitative RT-PCR and immunofluorescence studies for MAOA, MAOB, tyrosine hydroxylase, dopamine β-hydroxylase, L-amino acid decarboxyla...Continue Reading

Citations

Jan 8, 2016·Cellular Signalling·Yutaro ObaraNorimichi Nakahata
Jan 15, 2014·Clinica Chimica Acta; International Journal of Clinical Chemistry·Melanie GlauserEric Grouzmann
Jun 30, 2016·Clinical Chemistry·Karim AbidEric Grouzmann
Nov 20, 2016·Journal of Veterinary Internal Medicine·N FouchéC Navas de Solis

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