All-trans-retinoic acid ameliorates atherosclerosis, promotes perivascular adipose tissue browning, and increases adiponectin production in Apo-E mice

Figures

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  Figure 1. Total cholesterol, HDL, and LDL/VLDL concentrations of C57BL/6 J and Apo-E mice. All-trans-retinoic acid (5 mg/kg/day) or vehicle (corn oil) was administered orally by plastic feeding tubes for 8 weeks. Results are presented as means ± S.E.M. of 5–6 mice per group. The results were analyzed by two‐way ANOVA with Bonferroni post‐test. *p < 0.01 ApoE atRA vs. ApoE vehicle.

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  Figure 2. Microscopic analysis of the intimal lesions in the aortic roots. All-trans-retinoic acid (5 mg/kg/day) or vehicle (corn oil) were administered orally by plastic feeding tubes to Apo-E and C57BL/6J mice for 8 weeks. (A) The Oil Red O‑stained cross-sections of the aortic roots revealing the area of the lesions (magnification × 10 and × 40). (B) Average size of the atherosclerotic plaques in the aortic root. (C) Average sizes of the atherosclerotic lesion areas of eight individual cross-sections of the aortic root of each mouse. Data are expressed as the mean ± SEM of 5–6 mice per group. The results were analyzed by one‐way ANOVA with Tukey’s Multiple Comparison Test. ***p < 0.001 ApoE atRA vs. ApoE vehicle.

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  Figure 3. Browning of perivascular adipose tissue after all-trans-retinoic acid administration in Apo-E mice. (A) Adipose thermogenic gene expression: Ucp1, Cidea, and Prdm16. (B) Perivascular adipose tissue UCP1 immunohistochemical staining. (C) UCP1 protein expression was determined by Western Blot. All-trans-retinoic acid (5 mg/kg/day) or vehicle (corn oil) was administered orally by plastic feeding tubes to Apo-E and C57BL/6J mice for 8 weeks. Data are shown as mean ± SEM of 5–6 mice per group. The results were analyzed by one‐way ANOVA with Tukey's Multiple Comparison Test. *p < 0.05 C57BL/6J atRA vs. C57BL/6J vehicle, ApoE atRA vs. ApoE vehicle; **p < 0.01 ApoE atRA vs. ApoE vehicle; ***p < 0.001 C57BL/6J atRA vs. C57BL/6J vehicle, and ApoE atRA vs. ApoE vehicle. Full-length blots are presented in Supplementary Fig. S1.

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  Figure 4. The all-trans-retinoic acid treatment increased adiponectin synthesis and secretion by perivascular adipose tissue. (A) Adiponectin concentration in perivascular adipose tissue. (B) Adiponectin concentration in visceral adipose tissue. (C) mRNA adiponectin level in perivascular adipose tissue. (D) Adiponectin concentration in the conditioned medium after 24 h incubation with perivascular adipose tissue explants. All-trans-retinoic acid (5 mg/kg/day) or vehicle (corn oil) were administered orally by plastic feeding tubes to Apo-E and C57BL/6J mice for 8 weeks. Data are shown as mean ± SEM of 5–6 mice per group. The results were analyzed by one-way ANOVA with Tukey’s Multiple Comparison Test. *p < 0.05 ApoE atRa vs. ApoE vehicle.

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  Figure 5. The all-trans-retinoic acid treatment did not affect TNF-α synthesis and secretion by perivascular adipose tissue. (A) mRNA TNF-α level in perivascular adipose tissue. (B) TNF-α concentration in perivascular adipose tissue. (C) TNF-α concentration in the conditioned medium after 24 h incubation with perivascular adipose tissue explants. All-trans-retinoic acid (5 mg/kg/day) or vehicle (corn oil) were administered orally by plastic feeding tubes to Apo-E and C57BL/6J mice for 8 weeks. Data are shown as mean ± SEM of 5–6 mice per group. The results were analyzed by one-way ANOVA with Tukey’s Multiple Comparison Test.

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  Figure 6. Nitric oxide and adiponectin concentrations in the abdominal aorta of C57BL/6J and Apo-E mice. All-trans-retinoic acid (5 mg/kg/day) or vehicle (corn oil) were administered orally by plastic feeding tubes to Apo-E and C57BL/6J mice for 8 weeks. (A) Nitric oxide level in the abdominal aorta. (B) Adiponectin concentration in the abdominal aorta. Data are shown as mean ± SEM of 5–6 mice per group. The results were analyzed by one‐way ANOVA with Tukey’s Multiple Comparison Test. *p < 0.05 ApoE atRA vs. ApoE vehicle.