Enhanced peroxisomal β-oxidation metabolism in visceral adipose tissues of high-fat diet-fed obesity-resistant C57BL/6 mice

Abstract

This study aimed to investigate the potential mechanisms of natural resistance to high-fat diet-induced obesity. Four-week-old C57BL/6 mice were fed a high-fat diet for 6 weeks and were then designated as high-fat diet-fed obesity-prone (HOP) and obesity-resistant (HOR) animals. Their blood biochemistry was evaluated, and visceral adipose tissue samples were subjected to proteomic, Western blot and quantitative real-time PCR (q-PCR) analyses. The HOR mice showed reduced visceral fat weight and size, as well as lowered serum lipid and leptin levels. Proteomic analysis showed that enoyl coenzyme A hydratase 1, peroxisomal (Ech1) expression was significantly increased in their visceral adipose tissues. Moreover, other proteins, such as α-tropomyosin, myosin light chain, urine-nucleoside phosphorylase and transgelin, were also significantly increased. Furthermore, q-PCR analysis showed that the expression of acyl-CoA oxidase 1 palmitoyl, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase and 3-oxoacyl-CoA thiolase responsible for peroxisomal β-oxidation was also up-regulated in the visceral adipose tissues of the HOR mice. The expression of peroxisome proliferator-activated receptor α (PPARα) was increased in the HOR mice as shown by Western blot analysis. Obesity-resistant animals show enhanced peroxisomal β-oxidation metabolism and reduced fat accumulation in visceral adipose tissues by up-regulating the expression of Ech1, peroxisomal or other related peroxisomal β-oxidation marker genes, which may be driven or enhanced by the up-regulation of the expression of PPARα. However, further validation in future studies is required.

Figure 1.

Changes in the body weight (A; n=10), visceral fat weight (B; n=10), and visceral adipocyte size (C and D; n=100) in obesity-prone and obesity-resistant mice fed a high-fat diet for 6 weeks. HOP, high-fat diet-fed obesity-prone mice; HOR, high-fat diet-fed obesity-resistant mice. Data are expressed as the mean ± SD. ^**P<0.01 vs. HOP.

Figure 2.

Image of 2DE of the visceral adipose tissues in HOP (A) and HOR (B) (n=3) mice. Differentially expressed proteins are indicated with a circle. Protein spots: 2, α-tropomyosin; 3, myosin light chain, phosphorylatable, fast skeletal muscle; 4, purine-nucleoside phosphorylase; 5, enoyl coenzyme A hydratase 1, peroxisomal; 6, transgelin; 8, vimentin. HOP, high-fat diet-fed obesity-prone mice; HOR, high-fat diet-fed obesity-resistant mice.

Figure 2.

Image of 2DE of the visceral adipose tissues in HOP (A) and HOR (B) (n=3) mice. Differentially expressed proteins are indicated with a circle. Protein spots: 2, α-tropomyosin; 3, myosin light chain, phosphorylatable, fast skeletal muscle; 4, purine-nucleoside phosphorylase; 5, enoyl coenzyme A hydratase 1, peroxisomal; 6, transgelin; 8, vimentin. HOP, high-fat diet-fed obesity-prone mice; HOR, high-fat diet-fed obesity-resistant mice.

Figure 3.

Images of the differential expression of enoyl coenzyme A hydratase 1, peroxisomal (Ech1) determined by 2DE in the visceral adipose tissues of HOP (A) and HOR (B) mice after 6 weeks of treatment. Spots of interest are marked and enlarged (n=3). Protein expression (C) and relative grey densities (D) as determined by Western blotting in visceral adipose tissues of HOP and HOR mice. Data are expressed as the mean ± SD (n=5). ^*P<0.05, ^**P<0.01 vs HOP. HOP, high-fat diet-fed obesity-prone mice; HOR, high-fat diet-fed obesity-resistant mice.

Figure 4.

Expression of Acox1, Ehhadh, Acaal and Hadhb mRNAs in the visceral adipose tissues in mice determined by quantitative real-time PCR. HOP, high-fat diet-fed obesity-prone mice; HOR, high-fat diet-fed obesity-resistant mice. Data are expressed as the mean ± SD (n=5). ^**P<0.01 vs. HOP.