Mechanisms of the antilipolytic response of human adipocytes to tyramine, a trace amine present in food
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ORIGINAL ARTICLE
Mechanisms of the antilipolytic response of human adipocytes to tyramine, a trace amine present in food Christian Carpéné 1
&
Jean Galitzky 1 & Chloé Belles 2 & Alexia Zakaroff-Girard 1
Received: 20 November 2017 / Accepted: 9 July 2018 # University of Navarra 2018
Abstract Tyramine is found in foodstuffs, the richest being cheeses, sausages, and wines. Tyramine has been recognized to release catecholamines from nerve endings and to trigger hypertensive reaction. Thereby, tyramine-free diet is recommended for depressed patients treated with irreversible inhibitors of monoamine oxidases (MAO) to limit the risk of hypertension. Tyramine is a substrate of amine oxidases and also an agonist at trace amine-associated receptors. Our aim was to characterize the dose-dependent effects of tyramine on human adipocyte metabolic functions. Lipolytic activity was determined in adipocytes from human subcutaneous abdominal adipose tissue. Glycerol release was increased by a fourfold factor with classical lipolytic agents (1 μM isoprenaline, 1 mM isobutylmethylxanthine) while the amine was ineffective from 0.01 to 100 μM and hardly stimulatory at 1 mM. Tyramine exhibited a partial antilipolytic effect at 100 μM and 1 mM, which was similar to that of insulin but weaker than that obtained with agonists at purinergic A1 receptors, α2-adrenoceptors, or nicotinic acid receptors. Gi-protein blockade by Pertussis toxin abolished all these antilipolytic responses save that of tyramine. Indeed, tyramine antilipolytic effect was impaired by MAO-A inhibition. Tyramine inhibited protein tyrosine phosphatase activities in a manner sensitive to ascorbic acid and amine oxidase inhibitors. Thus, millimolar tyramine restrained lipolysis via the hydrogen peroxide it generates when oxidized by MAO. Since tyramine plasma levels have been reported to reach 0.2 μM after ingestion of 200 mg tyramine in healthy individuals, the direct effects we observed in vitro on adipocytes could be nutritionally relevant only when the MAO-dependent hepato-intestinal detoxifying system is overpassed. Keywords Trace amines . Adipocyte . Lipolysis . Antilipolysis . Monoamine oxidase . Hydrogen peroxide
Introduction Tyramine is one of the biogenic amines currently found in foods and beverages such as wines and beers [35]. Tyramine content can overpass 3.5 mg/L in red wine and varies considerably according to grape variety or cultivars, but remains less abundant than putrescine or histamine ([26, 35]. Although belonging to the family of the so-called trace amines, tyramine
* Christian Carpéné [email protected] 1
INSERM U 1048 équipe 1, Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale (INSERM U1048), Université Paul Sabatier (I2MC-UPS), I2MC, Bât. L4, CHU Rangueil, BP 84225, 31432 Toulouse CEDEX 4, France
2
DIVA Expertise, Centre Pierre Potier, Toulouse, France
can be found up to levels above 300 mg/kg in dry sausages [25], cheeses [44], or fishery products [19], and is
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