Hepatic–vascular crosstalk via GRK2: fenofibrate improves endothelial function by restoring lipid metabolism and NO signaling in obese mice

Figures

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  FIGURE 1. Concentration response curves and NO levels to ACh and SNP and clonidine in aortic rings. (A) Acetylcholine (ACh)-induced endothelial relaxation after PGF2α precontraction in aorta of SD (control; standard diet), SD-FF (fenofibrate-treated control), HFD (high-fat diet), and HFD-FF (fenofibrate-treated HFD) mice (n = 5, mean ± SE). (B) sodium nitroprusside (SNP)-induced relaxation after PGF2α precontraction in the aorta of SD, SD-FF, and HFD mice (n = 5, mean ± SE). (C) Clonidine-induced relaxation after PGF2α precontraction in the aorta of SD, SD-FF, HFD, and HFD-FF mice (n = 5, mean ± SE). (D) Levels of NO under nonstimulation (for 20 min) in aortic tissues from SD, SD-FF, HFD, and HFD-FF (n = 6, mean ± SE). (E) Levels of NO under ACh-stimulation (10–6 M, for 20 min) in aortic tissues from SD, SD-FF, HFD, and HFD-FF (n = 6, mean ± SE). (F) Levels of NO under clonidine-stimulation (10–6 M, for 20 min) in aortic tissues from SD, SD-FF, HFD, and HFD-FF (n = 6, mean ± SE). *p < 0.05; **p < 0.01 vs. SD. #p < 0.05; ##p < 0.01 vs. HFD.

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  FIGURE 2. Fenofibrate treatment normalizes vascular relaxation via the Akt pathway in HFD mice. (A) Effect of 30-min preincubation with Akt inhibitor (10–6 M) on ACh-induced relaxation in the aorta from SD and SD-FF (n = 6, mean ± SE). (B) Effect of 30-min preincubation with Akt inhibitor (10–6 M) on ACh-induced relaxation in aorta from HFD and HFD-FF (n = 6, mean ± SE). (C) Effect of 30-min preincubation with Akt inhibitor (10–6 M) on clonidine-induced relaxation in aorta from SD and SD-FF (n = 5, mean ± SE). (D) Effect of 30-min preincubation with Akt inhibitor (10–6 M) on clonidine-induced relaxation in aorta from HFD and HFD-FF (n = 5, mean ± SE). *p < 0.05 vs. SD. &p < 0.05 vs. SD-FF. #p < 0.05 vs. HFD. $p < 0.05 vs. HFD-FF.

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  FIGURE 3. Fenofibrate treatment normalizes vascular relaxation via the AMPK pathway in HFD mice. (A) Effect of 30-min preincubation with Compound C (CC; 5 × 10−6 M) on ACh-induced relaxation in the aorta from SD and SD-FF (n = 5, mean ± SE). (B) Effect of 30-min preincubation with CC (5 × 10−6 M) on ACh-induced relaxation in the aorta from HFD and HFD-FF (n = 5, mean ± SE). (C) Effect of 30-min preincubation with CC (5 × 10−6 M) on clonidine-induced relaxation in the aorta from SD and SD-FF (n = 5, mean ± SE). (D) Effect of 30-min preincubation with CC (5 × 10−6 M) on clonidine-induced relaxation in the aorta from HFD and HFD-FF (n = 5, mean ± SE). *p < 0.05, ***p < 0.001 vs. SD. &&&p < 0.001 vs. SD-FF. #p < 0.05 vs. HFD. $$p < 0.01, $$$p < 0.001 vs. HFD-FF.

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  FIGURE 4. Effect of fenofibrate on regulating the NO production signaling pathway and those related to protein activation in the aorta. The protein levels were measured by Western blot assay in the aortas of SD, SD-FF, HFD, and HFD-FF mice. (A) Representative Western blots and quantification of (B) p-Akt; (C) p-AMPK; (D) p-LKB1; (E) GRK2 proteins; and (F) GRK2 activity (n = 6, mean ± SE). *p < 0.05, **p < 0.01 vs. SD. #p < 0.05, ##p < 0.01 vs. HFD. ##p < 0.01, ###p < 0.001 vs. HFD. &p < 0.05, &&p < 0.01 vs. SD-FF.

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  FIGURE 5. Effect of fenofibrate on the expression and activity of GRK2 in the liver. Protein levels were measured by Western blot assay in the livers of SD, SD-FF, HFD, and HFD-FF mice. (A) Representative Western blots, quantification of (B) GRK2 proteins, and (C) GRK2 activity (n = 6, mean ± SE). *p < 0.05, **p < 0.01 vs. SD. ##p < 0.01 vs. HFD. &&p < 0.01 vs. SD-FF.