Published online Dec 15, 2020. doi: 10.4239/wjd.v11.i12.622
Peer-review started: August 31, 2020
First decision: October 5, 2020
Revised: October 12, 2020
Accepted: October 26, 2020
Article in press: October 26, 2020
Published online: December 15, 2020
Processing time: 103 Days and 18 Hours
Benzylamine and methylamine activate glucose uptake in adipocytes. For tyramine, this effect has even been extended to cardiomyocytes.
To investigate the effects of catecholamines and other amines on glucose uptake.
A screening compared 25 biogenic amines on 2-deoxyglucose (2-DG) uptake activation in rat adipocytes. Pharmacological approaches and transgenic mouse models were then used to decipher the mode of action of several hits.
In rat adipocytes, insulin stimulation of 2-DG uptake was reproduced with catecholamines. 100 µmol/L or 1 mmol/L adrenaline, noradrenaline, dopamine and deoxyepinephrine, maximally activated hexose transport only when sodium orthovanadate was added at 100 µmol/L. Such activation was similar to that already reported for benzylamine, methylamine and tyramine, well-recognized substrates of semicarbazide-sensitive amine oxidase (SSAO) and monoamine oxidase (MAO). Several, but not all, tested agonists of β-adrenoreceptors (β-ARs) also activated glucose transport while α-AR agonists were inactive. Lack of blockade by α- and β-AR antagonists indicated that catecholamine-induced 2-DG uptake was not mediated by AR stimulation. Adipocytes from mice lacking β1-, β2- and β3-ARs (triple KO) also responded to millimolar doses of adrenaline or noradrenaline by activating hexose transport in the presence of 100 µmol/L vanadate. The MAO blocker pargyline, and SSAO inhibitors did not block the effects of adrenaline or noradrenaline plus vanadate, which were blunted by antioxidants.
Catecholamines exert unexpected insulin-like actions in adipocytes when combined with vanadium. For limiting insulin resistance by activating glucose consumption at least in fat stores, we propose that catecholamine derivatives combined with vanadium can generate novel complexes that may have low toxicity and promising anti-diabetic properties.
Core Tip: In rat and mouse fat cells, the combination of catecholamines with vanadium reproduces the sugar entry activation already reported for benzylamine, methylamine or tyramine. Glucose transport stimulation is observed only with catecholamines at millimolar doses and in the presence of a vanadium dose that is ineffective on its own. The synergism between adrenaline or noradrenaline and vanadate is not mediated by adrenoceptors and resists amine oxidase inhibitors; while it is sensitive to antioxidants. Since vanadium exhibits antidiabetic properties, but with toxicological concerns, it is proposed that the combination of catecholamine derivatives plus vanadate salts might generate complexes with safer blood glucose-lowering properties.