Effects of Dietary Procyanidins and Tea Polyphenols on Adipose Tissue Mass and Fatty Acid Metabolism in Rats on a High Fat Diet

Abstract Background: The aim of this study was to investigate the effect of Acer tegmentosum Maxim (ATM) on adipocyte differentiation in 3T3-L1 adipocyte-derived cells and anti-obesity properties in high fat diet (HFD)-induced obese rats. Methods: 3T3-L1 adipocytes and HFD-induced obese rats were treated with ATM, and its effect on gene expression was analyzed using RT-PCR and Western blotting experiments. Results: Cellular lipid contents in DMI (dexamethasone, 3-isobutyl-1-methylxanthine, and insulin mixture)-treated cells increased, while ATM treatment caused a significant reduction in lipid accumulation in differentiated 3T3-L1 cells. ATM caused inhibition of adipogenesis via down-regulation of the CCAAT/enhancer binding protein β (C/EBPβ), C/EBPα, and peroxisome proliferator-activated receptor γ (PPARγ) expressions in 3T3-L1 cells. Moreover, treatment with ATM caused a decrease in the expressions of adipocyte-specific genes, such as adipocyte fatty acid-binding protein-2 (aP2), fatty acid synthase (FAS), and lipoprotein lipase (LPL), compared with DMI-stimulated adipocytes. In addition, phosphorylation levels of protein kinase B (Akt) and its downstream substrate, glycogen synthase kinase 3β (GSK3β), were significantly decreased by ATM treatment of 3T3-L1 adipocytes. Together, these results indicated that ATM caused inhibition of both adipocyte differentiation via suppression of the C/EBP family and PPARγ expressions and the Akt signaling pathway in 3T3-L1 adipocytes. In the present study, we further investigated anti-obesity effects of ATM on HFD-induced obese rats. Rats fed with HFD demonstrated elevations in body weight gain, while the administration of ATM significantly reversed BW gains and adipose tissue weights in rats fed HFD. ATM supplementation also caused a decrease in the circulating triglyceride levels and total cholesterol levels and led to inhibition of lipid accumulation in the adipose tissues in HFD-induced obesity in rats. Furthermore, epididymal fat exhibited larger adipocytes in the HFD group, whereas the ATM-treated group was significantly smaller than that of HFD group. These results strongly demonstrate that ATM administration caused a reduction in adiposity via attenuation in adipose tissue mass and adipocyte size. Conclusion: These finding demonstrated that ATM exerted anti-obesity effects through inhibition of adipocyte differentiation and adipogenesis, leading to a decrease in BW and fat tissue mass in HFD-induced obesity in rats.

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Activation of the adipocyte CREB/CRTC pathway in obesity

Communications Biology ◽

10.1038/s42003-021-02735-5 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Young-Sil Yoon ◽

Weiyi Liu ◽

Sam Van de Velde ◽

Shigenobu Matsumura ◽

Ezra Wiater ◽

...

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

High Fat Diet ◽

Type Ii Diabetes ◽

High Fat ◽

Tissue Mass ◽

Pparγ Agonist ◽

Adipose Tissue Mass ◽

Factor C ◽

Pro Inflammatory Cytokines

AbstractObesity is a major risk factor for the development of type II diabetes. Increases in adipose tissue mass trigger insulin resistance via the release of pro-inflammatory cytokines from adipocytes and macrophages. CREB and the CRTC coactivators have been found to promote insulin resistance in obesity, although the mechanism is unclear. Here we show that high fat diet feeding activates the CREB/CRTC pathway in adipocytes by decreasing the expression of SIK2, a Ser/Thr kinase that phosphorylates and inhibits CRTCs. SIK2 levels are regulated by the adipogenic factor C/EBPα, whose expression is reduced in obesity. Exposure to PPARγ agonist rescues C/EBPα expression and restores SIK2 levels. CRTC2/3 promote insulin resistance via induction of the chemokines CXCL1/2. Knockout of CRTC2/3 in adipocytes reduces CXCL1/2 expression and improves insulin sensitivity. As administration of CXCL1/2 reverses salutary effects of CRTC2/3 depletion, our results demonstrate the importance of the CREB/CRTC pathway in modulating adipose tissue function.

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