title: Inhibition of rat fat cell lipolysis by monoamine oxidase and semicarbazide-sensitive amine oxidase substrates.
abstract: It has been demonstrated that amine oxidase substrates stimulate glucose transport in cardiomyocytes and adipocytes, promote adipogenesis in pre-adipose cell lines and lower blood glucose in diabetic rats. These insulin-like effects are dependent on amine oxidation by semicarbazide-sensitive amine oxidase or by monoamine oxidase. The present study aimed to investigate whether amine oxidase substrates also exhibit another insulin-like property, the inhibition of lipolysis. We therefore tested the influence of tyramine and benzylamine on lipolytic activity in rat adipocytes. These amines did not modify basal lipolysis but dose-dependently counteracted the stimulation induced by lipolytic agents. The response to 10 nM isoprenaline was totally inhibited by tyramine 1 mM. The blockade produced by inhibition of amine oxidase activity or by 1 mM glutathione suggested that the generation of oxidative species, which occurs during amine oxidation, was involved in tyramine antilipolytic effect. Among the products resulting from amine oxidation, only hydrogen peroxide was antilipolytic in a manner that was potentiated by vanadate, as for tyramine or benzylamine. Antilipolytic responses to tyramine and to insulin were sensitive to wortmannin. These data suggest that inhibition of lipolysis is a novel insulin-like effect of amine oxidase substrates which is mediated by hydrogen peroxide generated during amine oxidation.
authors.affiliation: Institut Louis Bugnard, Institut National de la Santé et de la Recherche Médicale, Unité 586, C.H.U. Rangueil, Toulouse Cedex F-31403, France.
authors.forename: Virgile
authors.initials: V
authors.lastname: Visentin
authors.forename: Danielle
authors.initials: D
authors.lastname: Prévot
authors.forename: Luc
authors.initials: L
authors.lastname: Marti
authors.forename: Christian
authors.initials: C
authors.lastname: Carpéné
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000378:metabolism / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D008995:Monoamine Oxidase / Q000187:drug effects / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D010084:Oxidation-Reduction; D010293:Pargyline / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011794:Quercetin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D014439:Tyramine / Q000378:metabolism / Q000494:pharmacology*; D014638:Vanadates / Q000494:pharmacology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D001596:Benzylamines; D004791:Enzyme Inhibitors; D007328:Insulin; D008996:Monoamine Oxidase Inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D014638:Vanadates; D011794:Quercetin; D010293:Pargyline; C030796:benzylamine; D006861:Hydrogen Peroxide; D006631:Amine Oxidase (Copper-Containing); D008995:Monoamine Oxidase; D005978:Glutathione; D007545:Isoproterenol; D014439:Tyramine; D000077191:Wortmannin