iWAT Of Mice Research Articles

Flavonoid extracts of Citrus aurantium L. var. amara Engl. Promote browning of white adipose tissue in high-fat diet-induced mice

Ethnopharmacological relevanceObesity has become a public burden worldwide due to its booming incidence and various complications, and browning of white adipose tissue (WAT) is recognized as a hopeful strategy to combat it. Blossom of Citrus aurantium L. var. amara Engl. (CAVA) is a popular folk medicine and dietary supplement used for relieving dyspepsia, which is recorded in the Chinese Materia Medica. Our previous study showed that blossom of CAVA had anti-obesity potential, while its role in browning of WAT was still unclear. Aim of the studyThis study aimed to characterize the constituents in flavonoids from blossom of CAVA (CAVAF) and to clarify the anti-obesity capacities especially the effects on browning of WAT. Materials and methodsGradient ethanol eluents from blossom of CAVA were obtained by AB-8 macroporous resin. 3T3-L1 cells and pancreatic lipase inhibition assay were employed to investigate the potential anti-obesity effects in vitro. HPLC and UPLC/MS assays were performed to characterize the chemical profiles of different eluents. Network pharmacology and molecular docking assays were used to reveal potential anti-obesity targets. Furthermore, high-fat diet (HFD)-induced mice were constructed to explore the anti-obesity actions and mechanisms in vivo. Results30% ethanol eluents with high flavonoid content and great inhibition on proliferation of 3T3-L1 preadipocytes and pancreatic lipase activity were regarded as CAVAF. 19 compounds were identified in CAVAF. Network pharmacology analysis demonstrated that AMPK and PPARα were potential targets for CAVAF in alleviating obesity. Animal studies demonstrated that CAVAF intervention significantly decreased the body weight, WAT weight, serum TG, TC and LDL-C levels in HFD-fed obese mice. HFD-induced insulin resistance and morphological changes in WAT and brown adipose tissue were also markedly attenuated by CAVAF treatment. CAVAF supplementation potently inhibited iWAT inflammation by regulating IL-6, IL-1β, TNF-α and IL-10 mRNA expression in iWAT of mice. Furthermore, the gene expression levels of thermogenic markers including Cyto C, ATP synthesis, Cidea, Cox8b and especially UCP1 in iWAT of mice were significantly up-regulated by CAVAF administration. CAVAF intervention also markedly increased the expression levels of PRDM16, PGC-1α, SIRT1, AMPK-α1, PPARα and PPARγ mRNA in iWAT of mice. ConclusionCAVAF treatment significantly promoted browning of WAT in HFD-fed mice. These results suggested that flavonoid extracts from blossom of CAVA were probably promising candidates for the treatment of obesity.

Early macrophage-mediated Bdnf expression in white adipose tissue during high-fat diet feeding

The expression of brain-derived neurotrophic factor (BDNF) is observed not only in the brain, but also in peripheral tissues including white adipose tissues (WATs). Here, we showed that the mRNA expression of Bdnf in inguinal WAT (iWAT) and epididymal WAT (eWAT) increased within 2 weeks of feeding mice with a high-fat diet (HFD). In mice on a 2-week HFD, the induction of Bdnf expression in WATs was significantly correlated with increases in body weight, suggesting that Bdnf expression may increase at an early stage of obesity. The mRNA expression of hypoxia-inducible factor 1α and platelet-derived growth factor, which are involved in neovascularization and the subsequent expansion of adipose tissues, increased in the iWAT of mice on the 2-week HFD. We also found that the expression of macrophage marker F4/80 in iWAT increased under the HFD. Interestingly, HFD-induced Bdnf expression in iWAT was not observed when macrophages were removed by the administration of clodronate liposomes. Accordingly, mice receiving clodronate liposomes also exhibited a significant reduction in the HFD-induced increase in body weight. In conclusion, increased body weight in HFD-induced obese model mice was accompanied by the induction of Bdnf expression in iWAT and was probably mediated by macrophages. Our findings imply a novel function for BDNF in iWAT at an early stage of obesity.

Browning Subcutaneous White Adipose Tissue Using Transdermal Delivery of ASC-Targeting Peptide and Resveratrol Conjugate

Objectives Trans-resveratrol (RES) can significantly enhance the browning of subcutaneous white adipose tissue (WAT) when delivered to adipose stromal stem cells (ASCs) in WAT, the precursors of beige adipocytes. ASC-targeting peptide (GSWKYWFGEGGC) and RES have been conjugated using succinyl as a linker. The objective of this study is to transdermally deliver ASC-targeting peptide-RES conjugate directly to subcutaneous WAT using microneedle (MN) and iontophoresis (INT) and validate their browning and anti-obesity efficacy in obese mice.MethodsDissolving MN patches were developed using carboxymethylcellulose (CMC). Delivery effectiveness of MN was determined by an in vivo fluorescence imaging after applying dye-loaded MN on the skin above inguinal WAT (iWAT) in mice. Peptide-RES conjugate was loaded into CMC MN that was applied on the skins above iWAT of mice. After MN were dissolved, INT patch was applied to enhance penetration. Male C57BL/6J mice (5/group) were fed ahigh fat diet for 9 weeks. After 4 weeks of the high fat diet, mice were randomly divided into 3 groups as 1. MN (Blank)+INT, 2. MN (free RES)+INT, and 3. MN (peptide-RES conjugate) +INT. Mice received treatments 2 times/week from week 5 to 9. Food intake, body weight, and body composition were measured weekly, and the glucose tolerance test was conducted at week 9.ResultsMN (dye)+INT-treated mice had 2-fold higher dye signals in iWAT as compared to mice treated with MN alone. Dye signals in other organs/tissues were too low to be detected indicating the success of local (MN + INT) delivery and less diffusion. After 5 weeks of treatment, mice treated with MN (peptide-RES conjugate)+INT as compared to other two groups of mice had more than 1.5-fold lower body weight and fat%, 1.4-fold lower blood glucose levels, and more than 3-fold iWAT mRNA levels of UCP1 indicating browning of iWAT.ConclusionsTransdermal delivery of ASC-targeting peptide-RES conjugate to iWAT induces browning of subcutaneous WAT, resulting in body weight and fat loss in obese mice. Transdermal delivery might provide an innovative and efficient approach for combating obesity and its comorbidities.Funding SourcesNIH 1R15AT010395-01 and American Heart Association 19AIREA34480011.

L-Theanine Activates the Browning of White Adipose Tissue Through the AMPK/α-Ketoglutarate/Prdm16 Axis and Ameliorates Diet-Induced Obesity in Mice.

l-Theanine is a nonprotein amino acid with much beneficial efficacy. We found that intraperitoneal treatment of the mice with l-theanine (100 mg/kg/day) enhanced adaptive thermogenesis and induced the browning of inguinal white adipose tissue (iWAT) with elevated expression of Prdm16, Ucp1, and other thermogenic genes. Meanwhile, administration of the mice with l-theanine increased energy expenditure. In vitro studies indicated that l-theanine induced the development of brown-like features in adipocytes. The shRNA-mediated depletion of Prdm16 blunted the role of l-theanine in promoting the brown-like phenotypes in adipocytes and in the iWAT of mice. l-theanine treatment enhanced AMPKα phosphorylation both in adipocytes and iWAT. Knockdown of AMPKα abolished l-theanine-induced upregulation of Prdm16 and adipocyte browning. l-Theanine increased the α-ketoglutarate (α-KG) level in adipocytes, which may increase the transcription of Prdm16 by inducing active DNA demethylation on its promoter. AMPK activation was required for l-theanine-induced increase of α-KG and DNA demethylation on the Prdm16 promoter. Moreover, intraperitoneal administration with l-theanine ameliorated obesity, improved glucose tolerance and insulin sensitivity, and reduced plasma triglyceride, total cholesterol, and free fatty acids in the high-fat diet-fed mice. Our results suggest a potential role of l-theanine in combating diet-induced obesity in mice, which may involve l-theanine-induced browning of WAT.

Sympathetic nerve innervation is required for beigeing in white fat.

It is increasingly recognized that activation of beige adipocyte thermogenesis by pharmacological or genetic approaches increases energy expenditure and alleviates obesity. Sympathetic nervous system (SNS) directly innervating brown adipose tissue (BAT) and white adipose tissue (WAT) plays a key role in promoting nonshivering thermogenesis. However, direct evidence that supports the importance of SNS innervation for beige adipocyte formation is still lacking, and the significance of beige adipocyte thermogenesis in protection of body temperature during cold challenge is not clear. Here we tested the necessity of SNS innervation into WAT for beige adipocyte formation in mice with defective brown fat thermogenesis via interscapular BAT (iBAT) SNS denervation. SNS denervation was achieved by microinjection of 6‐hydroxydopamine (6‐OHDA), a selective neurotoxin to SNS nerves, into iBAT, inguinal WAT (iWAT), or both. The partial chemical denervation of iBAT SNS down‐regulated UCP‐1 protein expression in iBAT demonstrated by immunoblotting and immunohistochemical measurements. This was associated with an up‐regulation of UCP1 protein expression and enhanced formation of beige cells in iWAT of mice with iBAT SNS denervation. In contrast, the chemical denervation of iWAT SNS completely abolished the upregulated UCP‐1 protein and beige cell formation in iWAT of mice with iBAT SNS denervation. Our data demonstrate that SNS innervation in WAT is required for beige cell formation during cold–induced thermogenesis. We conclude that there exists a coordinated thermoregulation for BAT and WAT thermogenesis via a functional cross talk between BAT and WAT SNS.

Artepillin C, a Typical Brazilian Propolis-Derived Component, Induces Brown-Like Adipocyte Formation in C3H10T1/2 Cells, Primary Inguinal White Adipose Tissue-Derived Adipocytes, and Mice.

Induction of brown-like adipocytes (beige/brite cells) in white adipose tissue (WAT) suggests a new approach for preventing and treating obesity via induction of thermogenesis associated with uncoupling protein 1 (UCP1). However, whether diet-derived factors can directly induce browning of white adipocytes has not been well established. In addition, the underlying mechanism of induction of brown-like adipocytes by diet-derived factors has been unclear. Here, we demonstrate that artepillin C (ArtC), which is a typical Brazilian propolis-derived component, significantly induces brown-like adipocytes in murine C3H10T1/2 cells and primary inguinal WAT (iWAT)-derived adipocytes. This significant induction is due to activation of peroxisome proliferator-activated receptor γ and stabilization of PRD1-BF-1-RIZ1 homologous domain-containing protein-16 (PRDM16). Furthermore, the oral administration of ArtC (10 mg/kg) for 4 weeks significantly induced brown-like adipocytes accompanied by significant expression of UCP1 and PRDM16 proteins in iWAT of mice, and was independent of the β3-adrenergic signaling pathway via the sympathetic nervous system. These findings may provide insight into browning of white adipocytes including the molecular mechanism mediated by dietary factors and demonstrate that ArtC has a novel biological function with regard to increasing energy expenditure by browning of white adipocytes.