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Am J Physiol Heart Circ Physiol. 2014 Apr 1;306(7):H1001-10. doi: 10.1152/ajpheart.00761.2013. Epub 2014 Jan 31.

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

Author information

1
Department of Anesthesiology and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota; and.

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 Ser(1177) 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.

KEYWORDS:

carotid artery; endothelial dysfunction; endothelial nitric oxide synthase; hydrogen peroxide; nitric oxide; peroxisome proliferator-activated receptor-δ; tetrahydrobiopterin

PMID:
24486511
PMCID:
PMC3962632
DOI:
10.1152/ajpheart.00761.2013
[Indexed for MEDLINE]
Free PMC Article

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