2.2. Animals

Male C57BL/6J mice, endothelium-specific PPARδ knockout mice (PPARδ^flox/flox, Cre⁺; PPARδ^EC-/-) and their wild-type littermates (PPARδ^flox/flox, Cre^-; WT) aged 8–10 weeks and weighing 20–25 g were used for this study. PPARδ^EC-/- mice were generated by crossing the PPARδ^flox/flox mice, which harbored the loxP sites flanking exon 4 of the murine Ppard gene, with the Tie2-Cre mice (Jackson Laboratory, Bar Harbor, ME, USA) as previously described [16]. The mice were housed in a temperature-controlled holding room (22–23 °C) with a 12-h light/dark cycle and fed standard chow and water. All animal care and experimental procedures were conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals with the approval by the Animal Research Committee of Xi'an Jiaotong University (No. XJTULAC2017-729). Mice were euthanized using CO₂ method following 2013 AVMA guidelines [17].