Mechanisms of vascular dysfunction in mice with endothelium-specific deletion of the PPAR-δ gene

Livius V. d'Uscio, Tongrong He, Anantha Vijay R. Santhanam, Li Jung Tai, Ronald M. Evans, Zvonimir S. Katusic

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Peroxisome proliferator-activated receptor (PPAR)-δ is a nuclear hormone receptor that is mainly involved in lipid metabolism. Recent studies have suggested that PPAR-δ agonists exert vascular protective effects. The present study was designed to characterize vascular function in mice with genetic inactivation of PPAR-δ in the endothelium. Mice with vascular endothelial cell-specific deletion of the PPAR-δ gene (ePPARδ-/- mice) were generated using loxP/Cre technology. ePPARδ-/- mice were normotensive and did not display any sign of metabolic syndrome. Endothelium-dependent relaxations to ACh and endothelium-independent relaxations to the nitric oxide (NO) donor diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate were both significantly impaired in the aorta and carotid arteries of ePPARδ-/- mice (P < 0.05). In ePPARδ-/- mouse aortas, phosphorylation of endothelial NO synthase at Ser1177 was significantly decreased (P < 0.05). However, basal levels of cGMP were unexpectedly increased (P < 0.05). Enzymatic activity of GTP-cyclohydrolase I and tetrahydrobiopterin levels were also enhanced in ePPARδ-/- mice (P < 0.05). Most notably, endothelium-specific deletion of the PPAR-δ gene significantly decreased protein expressions of catalase and glutathione peroxidase 1 and resulted in increased levels of H2O2 in the aorta (P < 0.05). In contrast, superoxide anion production was unaltered. Moreover, treatment with catalase prevented the endothelial dysfunction and elevation of cGMP detected in aortas of ePPARδ-/- mice. The findings suggest that increased levels of cGMP caused by H2O2 impair vasodilator reactivity to endogenous and exogenous NO. We speculate that chronic elevation of H2O2 predisposes PPAR-δ-deficient arteries to oxidative stress and vascular dysfunction.

Original languageEnglish (US)
Pages (from-to)H1001-H1010
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume306
Issue number7
DOIs
StatePublished - Apr 1 2014

Keywords

  • Carotid artery
  • Endothelial dysfunction
  • Endothelial nitric oxide synthase
  • Hydrogen peroxide
  • Nitric oxide
  • Peroxisome proliferator-activated receptor-δ
  • Tetrahydrobiopterin

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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