Resveratrol ameliorates diet-induced dysregulation of lipid metabolism in zebrafish (<i>Danio rerio</i>)

<div><p>Defective lipid metabolism is associated with increased risk of various chronic diseases, such as obesity, cardiovascular diseases, and diabetes. Resveratrol (RSV), a natural polyphenol, has been shown the potential of ameliorating disregulations of lipid metabolism. The objective of this study was to investigate the effects of feed intake and RSV on lipid metabolism in zebrafish (<i>Danio rerio</i>). The adult males were randomly allocated to 6 groups: control (Con, 8 mg cysts/fish/day), control with 20 μmol/L RSV (Con+RSV), calorie restriction (CR, 5 mg cysts/fish/day), calorie restriction with RSV (CR+RSV), overfeed (OF, 60 mg cysts/fish/day), and overfeed with RSV (OF+RSV) groups. The treatment period was 8 weeks. Results showed that CR reduced body length, body weight, and condition factor of zebrafish. CR reduced levels of plasma triglyceride (TG) and induced protein expression of phosphorylated AMP-activated protein kinase-α (pAMPKα), silent information regulator 2 homolog 1 (Sirt1), and peroxisome proliferator activated receptor gamma coactivator-1α (PGC1α). RSV attenuated CR-induced pAMPKα/AMPKαincreases. RSV increased levels of Sirt1 protein in the OF zebrafish, and decreased OF-induced increase in peroxisome proliferator-activated receptor-γ (PPARγ) protein level. Additionally, RSV down-regulated caveolin-1 and up-regulated microtubule-associated protein 1 light chain 3 -II (LC3-II) protein levels in OF zebrafish. In conclusion, these results suggest that 1) CR reduces plasma TG level through activation of the AMPKα-Sirt1- PGC1α pathway; 2) under different dietary stress conditions RSV might regulate AMPK phosphorylation bi-directionally; 3) RSV might regulate lipid metabolism through the AMPKα-Sirt1-PPARγ pathway in OF zebrafish.</p></div

Histopathological observation of liver tissue in zebrafish (×400 magnification, HE staining).

<p>A. Con, B. Con+RSV, C. CR, D. CR+RSV, E. OF, F. OF+RSV.</p

Effects of resveratrol on body length, body weight and condition factor in different diet zebrafish.

<p>Effects of resveratrol on body length, body weight and condition factor in different diet zebrafish.</p

Effects of feed intake and RSV on AMPKα and pAMPKα levels in zebrafish muscle.

<p>A. AMPK<b>α</b> mRNA levels, B. AMPK<b>α</b> protein levels, C. pAMPK<b>α</b> protein levels, D. Ratio of AMPK<b>α</b> protein level to pAMPK<b>α</b> protein level, E. Immunoblots of AMPK<b>α</b> and pAMPK<b>α</b>. The data were presented as Mean ± SD. Letters (a, b, c) indicated the multiple comparison results among various feed intake groups without RSV. Capital letters (A, B, C) indicated the multiple comparison results among various feed intake groups with RSV. Same letters indicated no significant difference, different letters indicated significant differences in statistics. * indicated the significant difference between groups without RSV and with RSV. For those there was no statistically significant difference between groups, the letters were not shown. Significance level was 0.05.</p

Effects of resveratrol on blood glucose, plasma total cholesterol and triglyceride in different diet zebrafish.

<p>Effects of resveratrol on blood glucose, plasma total cholesterol and triglyceride in different diet zebrafish.</p

Effects of feed intake and RSV on Cav-1 and LC3 in zebrafish muscle.

<p>A. Cav-1 protein level. B. Ratio of LC3-II protein level to LC3-I protein level. C. Co-immunoprecipitation (IP) and immunoblots (IB) of Cav-1 and LC3. The data were presented as Mean ± SD. Letters (a, b, c) indicated the multiple comparison results among various feed intake groups without RSV. Capital letters (A, B, C) indicated the multiple comparison results among various feed intake groups with RSV. Same letters indicated no significant difference, different letters indicated significant differences in statistics. * indicated the significant difference between groups without RSV and with RSV. For those there was no statistically significant difference between groups, the letters were not shown. Significance level was 0.05.</p

Effects of feed intake and RSV on Sirt1, PPARγ and PGC1α levels in zebrafish muscle.

<p>A. Sirt1 mRNA levels, B. Sirt1 protein levels, C. Immunoblots of Sirt1. D. PPARγ mRNA levels, E. PPARγ protein levels, F. Immunoblots of PPARγ. G. PGC1α mRNA levels, H. PGC1α protein levels, I. Immunoblots of PGC1α. The data were presented as Mean ± SD. Letters (a, b, c) indicated the multiple comparison results among various feed intake groups without RSV. Capital letters (A, B, C) indicated the multiple comparison results among various feed intake groups with RSV. Same letters indicated no significant difference, different letters indicated significant differences in statistics. * indicated the significant difference between groups without RSV and with RSV. For those there was no statistically significant difference between groups, the letters were not shown. Significance level was 0.05.</p

Environmentally Relevant Dose of Bisphenol A Does Not Affect Lipid Metabolism and Has No Synergetic or Antagonistic Effects on Genistein’s Beneficial Roles on Lipid Metabolism

<div><p>Both bisphenol A (BPA, an endocrine disrupting chemicals) and genistein (a phytoestrogen mainly derived from leguminosae) are able to bind to estrogen receptors, but they are considered to have different effects on metabolic syndrome, surprisingly. We here investigate the effects of an environmentally relevant dose of BPA alone and the combined effects with genistein on lipid metabolism in rats. Eight groups of adult male Wistar rats, fed with either standard chow diet or high-fat diet, were treated with BPA (50μg/kg/day), genistein (10mg/kg/day), and BPA plus genistein for 35 weeks, respectively. Metabolic parameters in serum and liver were determined; the hematoxylin/eosin and oil Red O staining were used to observe liver histologically; gene expressions related to hepatic lipid metabolism were analyzed by Real-time PCR; protein expressions of PPARγ, PPARα and LC3 in liver were analyzed by western blotting. No difference of body weight gain, total energy intake, liver weight/body weight or body fat percentage in both STD- and HFD-fed sub-groups was observed after treatment with BPA, genistein, or BPA plus genistein (<i>P</i>>0.05). Genistein alleviated lipid metabolism disorder and decreased the mRNA and protein expression of PPARγ (<i>P</i><0.05), and increased the protein expression of LC3II (<i>P</i><0.05) in liver of HFD-fed rats. However, BPA treatment had no effect on lipid metabolism in rats alone (<i>P</i>>0.05) or combined with genistein. Our findings suggest that long-term environmentally relevant dose of BPA did not affect lipid metabolism, and had no synergetic or antagonistic roles on genistein’s beneficial function on hepatic lipid metabolism.</p></div

Effects of BPA and genistein on body weight, total energy intake, liver weight/body weight and Subcutaneous body fat percentage in rats.

<p>(A)Body weight (n = 8–10). (B) Body weight gain (n = 8–10). (C) Total energy intake (n = 5). (D) liver weight/body weight (n = 8–10). (E) Subcutaneous body fat percentage (n = 8–10). Data are expressed as Mean ± SEM. * <i>P</i><0.05; ** <i>P</i><0.01 compared to STD group.</p

Morphological examination by oil Red O staining of liver tissue sections in STD- and HFD-fed rats.

<p>(A) STD, (B) STD-BPA, (C) STD-(BPA+G), (D) STD-G, (E) HFD, (F) HFD-(BPA+G), (G) HFD-G (400×magnification, Bar = 100 μm).</p