Obesity is associated with hyperleptinemia but it is not clear whether leptin protects vascular function or promotes dysfunction. We therefore studied the consequences of hyperleptinemia in lean mice. Wild-type and endothelial NO synthase (eNOS)(-/-) mice were infused with leptin (0.4 mg/kg per day, 7 days), and endothelium-dependent relaxation was studied in aortic segments. Leptin had no effect on acetylcholine-induced endothelium-dependent relaxation in normal wild-type mice but restored endothelium-dependent relaxation in wild-type mice treated with angiotensin II (0.7 mg/kg per day, 7 days) to induce endothelial dysfunction. Leptin also sensitized aortae from eNOS(-/-) mice to acetylcholine, an effect blocked by neuronal NOS (nNOS) inhibition and not observed in eNOS-nNOS double(-/-) mice. Consistent with these findings, leptin induced nNOS expression in murine and human vessels and human endothelial but not smooth muscle cells. Aortic nNOS expression was also induced in mice by a high-fat diet. Mechanistically, leptin increased endothelial Janus kinase 2 and signal transducer and activator of transcription 3 phosphorylation, and inhibition of Janus kinase 2 prevented nNOS induction in cultured cells and leptin-induced relaxations in eNOS(-/-) mice. Leptin induces endothelial nNOS expression, which compensates, in part, for a lack of NO production by eNOS to maintain endothelium-dependent relaxation.
|Number of pages||8|
|Journal||Arteriosclerosis, thrombosis, and vascular biology|
|Publication status||Published - 2012 Jul|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine