Leptin effect on endothelial nitric oxide is mediated through Akt-endothelial nitric oxide synthase phosphorylation pathway.
Recent evidence suggests that besides its action on the central nervous system, leptin can modulate vascular tone through local mechanisms involving nitric oxide (NO) release. In this study, using a fluorescent probe for direct determination of NO, we demonstrated both in endothelial cells and in vessels that leptin is able to stimulate NO release. The effect of leptin on NO is abolished by erbstatin A, a Ca(2+)-independent tyrosine kinase inhibitor, whereas it is not influenced by calcium removal or by other protein phosphorylation inhibitors, such as genistein (an ATP-dependent tyrosine-kinase inhibitor) or wortmannin and LY294002 (two different phosphatidylinositol [PI] 3-kinase inhibitors). Accordingly, leptin-induced vasorelaxation in aortic rings was abolished only by erbstatin A. Furthermore, immunoblotting studies revealed that leptin evokes Akt phosphorylation, with a comparable time course in both endothelial cells and vessels. Also in this experimental system, the effect of leptin was abolished by erbstatin A and not by other inhibitors. Finally, a considerable increase in endothelial NO synthase (eNOS) phosphorylation in Ser(1177) was found when vessels were treated with leptin. In conclusion, leptin induces NO production by activating a PI 3-kinase-independent Akt-eNOS phosphorylation pathway.
Vecchione
Carmine
C
IRCCS Neuromed, Pozzilli (IS), Italy.
Maffei
Angelo
A
Colella
Salvatore
S
Aretini
Alessandra
A
Poulet
Roberta
R
Frati
Giacomo
G
Gentile
Maria Teresa
MT
Fratta
Luigi
L
Trimarco
Valentina
V
Trimarco
Bruno
B
Lembo
Giuseppe
G
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006873:Hydroquinones / Q000494:pharmacology; D066298:In Vitro Techniques; D020738:Leptin / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D011921:Rats, Inbred WKY; D014664:Vasodilation / Q000187:drug effects; D000077191:Wortmannin
D000730:Androstadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D020738:Leptin; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019833:Genistein; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D011505:Protein-Tyrosine Kinases; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D002118:Calcium; C048212:erbstatin; D000077191:Wortmannin