High doses of tyramine stimulate glucose transport in human fat cells

Carpéné, Christian; Les, Francisco; Barceló, Josep Mercader; Boulet, Nathalie; Briot, Anaïs; Grolleau, J.-L.

doi:10.1007/s13105-021-00864-3

Cited by 8 publications

(14 citation statements)

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“…Since tyramine has been reported to activate glucose transport in human adipocytes [ 12 ], it was verified whether N -methyltyramine (NMT) could share the same property. Figure 1 summarizes this first comparative approach.…”

Section: Resultsmentioning

confidence: 99%

“…The data representation chosen for Student’s t paired analysis used in the tyramine panel also illustrated the substantial inter-individual variability that exists in the baseline of hexose uptake in human adipocytes. Data were redrawn from results obtained on freshly isolated adipocytes during our previous in vitro determinations of 2-deoxyglucose uptake (2-DG) [ 12 ]. A similar comparison between basal uptake and response to 1 mM NMT was performed in other adipocyte preparations obtained from 24 patients examined between 2018 and 2021 ( Figure 1 b).…”

Section: Resultsmentioning

confidence: 99%

“…This comparative approach indicated that both amines induced short-term activation of glucose transport in human adipocytes. Given the similarities between their chemical structure and effect, NMT was supposed to act as already stated for tyramine [ 12 ], i.e., as a MAO substrate generating via oxidative deamination a sufficient amount of hydrogen peroxide to trigger the translocation of glucose transporters to the fat cell surface.…”

Section: Resultsmentioning

confidence: 99%

“…To supply energy to the cells during the in vitro experiments, this medium contained 2 mM pyruvate, as described in [ 19 ]. The 2-DG uptake was stopped by the addition of 100 µM cytochalasin B, and by a separation between intracellular and extracellular hexose that was performed as previously described [ 12 ], via a spin through a dynonylphtalate layer in order to obtain undamaged radiolabeled fat cells [ 19 ].…”

Section: Methodsmentioning

confidence: 99%

“…These differential effects were explained by the capacity of tyramine to release norepinephrine in hAT and by opposite presynaptic and postsynaptic mechanisms. More recently, it has been observed that tyramine inhibits lipolysis [ 11 ] and activates glucose transport [ 12 ] in human adipocytes, when present at 0.01–1 mM during in vitro experiments lasting less than two hours. These direct effects were dependent on oxidation by monoamine oxidases, and mediated by hydrogen peroxide.…”

Section: Introductionmentioning

confidence: 99%

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Multiple Direct Effects of the Dietary Protoalkaloid N-Methyltyramine in Human Adipocytes

et al. 2022

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Dietary amines have been the subject of a novel interest in nutrition since the discovery of trace amine-associated receptors (TAARs), especially TAAR-1, which recognizes tyramine, phenethylamine, tryptamine, octopamine, N-methyltyramine (NMT), synephrine, amphetamine and related derivatives. Alongside the psychostimulant properties of TAAR-1 ligands, it is their ephedrine-like action on weight loss that drives their current consumption via dietary supplements advertised for ‘fat-burning’ properties. Among these trace amines, tyramine has recently been described, at high doses, to exhibit an antilipolytic action and activation of glucose transport in human adipocytes, i.e., effects that are facilitating lipid storage rather than mobilization. Because of its close structural similarity to tyramine, NMT actions on human adipocytes therefore must to be reevaluated. To this aim, we studied the lipolytic and antilipolytic properties of NMT together with its interplay with insulin stimulation of glucose transport along with amine oxidase activities in adipose cells obtained from women undergoing abdominal surgery. NMT activated 2-deoxyglucose uptake when incubated with freshly isolated adipocytes at 0.01–1 mM, reaching one-third of the maximal stimulation by insulin. However, when combined with insulin, NMT limited by half the action of the lipogenic hormone on glucose transport. The NMT-induced stimulation of hexose uptake was sensitive to inhibitors of monoamine oxidases (MAO) and of semicarbazide-sensitive amine oxidase (SSAO), as was the case for tyramine and benzylamine. All three amines inhibited isoprenaline-induced lipolysis to a greater extent than insulin, while they were poorly lipolytic on their own. All three amines—but not isoprenaline—interacted with MAO or SSAO. Due to these multiple effects on human adipocytes, NMT cannot be considered as a direct lipolytic agent, potentially able to improve lipid mobilization and fat oxidation in consumers of NMT-containing dietary supplements.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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