Mouse Epididymal Adipose Tissue Research Articles

The Hydrophilic Metabolite UMP Alleviates Obesity Traits through a HIF2α-ACER2-Ceramide Signaling Axis.

Metabolic abnormalities contribute to the pathogenesis of obesity and its complications. Yet, the understanding of the interactions between critical metabolic pathways that underlie obesity remains to be improved, in part owing to the lack of comprehensive metabolomics studies that reconcile data from both hydrophilic and lipophilic metabolome analyses that can lead to the identification and characterization of key signaling networks. Here, the study conducts a comprehensive metabolomics analysis, surveying lipids and hydrophilic metabolites of the plasma and omental adipose tissue of obese individuals and the plasma and epididymal adipose tissue of mice. Through these approaches, it is found that a significant accumulation of ceramide due to inhibited sphingolipid catabolism, while a significant reduction in the levels of uridine monophosphate (UMP), is critical to pyrimidine biosynthesis. Further, it is found that UMP administration restores sphingolipid homeostasis and can reduce obesity in mice by reversing obesity-induced inhibition of adipocyte hypoxia inducible factor 2a (Hif2α) and its target gene alkaline ceramidase 2 (Acer2), so as to promote ceramide catabolism and alleviate its accumulation within cells. Using adipose tissue Hif2α-specific knockout mice, the study further demonstrates that the presence of UMP can alleviate obesity through a HIF2α-ACER2-ceramide pathway, which can be a new signaling axis for obesity improvement.

Hypolipidemic mechanism of Pleurotus eryngii polysaccharides in high-fat diet-induced obese mice based on metabolomics.

In this study, the structure of Pleurotus eryngii polysaccharides (PEPs) was characterized, and the mechanism of PEP on obesity and hyperlipidemia induced by high-fat diet was evaluated by metabonomic analysis. The structure of PEPs were characterized by monosaccharide composition, Fourier transform infrared spectroscopy and thermogravimetry. In animal experiments, H&E staining was used to observe the morphological difference of epididymal adipose tissue of mice in each group. Ultrahigh performance liquid chromatography (UHPLC)-(QE) HFX -mass spectrometry (MS) was used to analyze the difference of metabolites in serum of mice in each group and the related metabolic pathways. The PEPs contained nine monosaccharides: 1.05% fucose, 0.30% arabinose, 17.94% galactose, 53.49% glucose, 1.24% xylose, 23.32% mannose, 1.30% ribose, 0.21%galacturonic acid, and 1.17% glucuronic acid. The PEPs began to degrade at 251°C (T0), while the maximum thermal degradation rate temperature (Tm) appeared at 300°C. The results histopathological observation demonstrated that the PEPs had signifificant hypolipidemic activities. After PEPs intervention, the metabolic profile of mice changed significantly. A total of 29 different metabolites were selected as adjunctive therapy to PEPs, for treatment of obesity and hyperlipidemia-related complications caused by a high-fat diet. These metabolites include amino acids, unsaturated fatty acids, choline, glycerol phospholipids, and other endogenous compounds, which can prevent and treat obesity and hyperlipidemia caused by a high-fat diet by regulating amino acid metabolism, fatty acid metabolism, and changes in metabolic pathways such as that involved in the citric cycle (TCA cycle). The presented results indicate that PEPs treatment can alleviate the obesity and hyperlipidemia caused by a high-fat diet and, thus, may be used as a functional food adjuvant, providing a theoretical basis and technical guidance for the prevention and treatment of high-fat diet-induced obesity and hyperlipidemia.

MiR-146a-5p, targeting ErbB4, promotes 3T3-L1 preadipocyte differentiation through the ERK1/2/PPAR-γ signaling pathway

BackgroundMicroRNAs (MiRNAs) are known to participate in preadipocyte differentiation, but the manner in which miR-146a-5p participates in this process remains unclear. This study was performed to examine the participation of miR-146a-5p in 3T3-L1 cell differentiation.Material and MethodsmiR-146a-5p expression was upregulated and down-regulated to examine effects on 3T3-L1 cell differentiation. Bioinformatics analysis was performed to predict its target genes, and the signaling pathway it regulates was identified by qRT-PCR and Western blotting. The expression of miR-146a-5p in epididymal adipose tissue from obese mice and in an obese mouse adipose cell model was examined by qRT-PCR.Results3T3-L1 cells differentiated into mature adipocytes successfully, as verified by increased areas of intracellular lipid droplets and elevated expression of mature adipocyte markers, and these cells had elevated miR-146a-5p expression. The intracellular lipid droplet and triglyceride contents and the expression of mature adipocyte markers were significantly increased in miR-146a-5p–overexpressing 3T3-L1 cells and markedly decreased in miR-146a-5p–inhibited 3T3-L1 cells. ErbB4 was a predicted target gene of miR-146a-5p. In miR-146a-5p–overexpressing 3T3-L1 cells, ErbB4 expression and ERK1/2 phosphorylation were decreased and the expression of PPAR-γ was increased; the opposite was observed in miR-146a-5p–inhibited 3T3-L1 cells. In addition, miR-146a-5p expression was significantly increased in the mouse epididymal adipose tissue and adipose cell model.ConclusionsUpregulated miR-146a-5p expression was related to 3T3-L1 cell differentiation. MiR-146a-5p promoted 3T3-L1 cell differentiation by targeting ErbB4 and via the ERK1/2/PPAR-γ signaling pathway.

Neutrophil extracellular traps (NETs) modulate inflammatory profile in obese humans and mice: adipose tissue role on NETs levels.

Neutrophilextracellular traps (NETs) are a recently discovered neutrophil defense mechanism whichmodulates several inflammatory conditions contributing to metabolic profile alterations. Therefore, the present study aimed to evaluate the production of NETs in obese patients and mice, verifying the possible mechanisms associated with the release of NETs by the adipose tissue. The present study investigated NETs production in human adipose tissue and also showing the neutrophils using intravital microscopy in mouse epididymal adipose tissue. Blood and white adipose tissues were obtained from eutrophic and obese individuals and from mice. Lipid, glycemic and leukocyte profiles were evaluated, as well as the levels of NETs and its markers. Bioinformatics and proteomics analyses were performed and the identified key proteins were measured. The main findings showed that the inflammatory markers interleukin-8 (IL-8), heat shock protein 90 (HSP90) and the E1 heat shock protein family (HSPE1) can be modulated by the NETs levels in obesity. Obesity has also been associated with increased cholesterol, glucose intolerance, ionic calcium and NETs. We also observed an increase in catalase and a decreased superoxide dismutase activity. Bioinformatics and proteomics analyses revealed that IL-8, HSP90 and HSPE1 were associated with obesity, inflammation and NETs release. In conclusion, the present study shows an increase in NETs production during obesity associated with important inflammatory markers in adipose.

Preparation of Adipose Progenitor Cells from Mouse Epididymal Adipose Tissues.

Obesity and metabolic disorders such as diabetes, heart disease, and cancer, are all associated with dramatic adipose tissue remodeling. Tissue-resident adipose progenitor cells (APCs) play a key role in adipose tissue homeostasis and can contribute to the tissue pathology. The growing use of single cell analysis technologies - including single-cell RNA-sequencing and single-cell proteomics - is transforming the stem/progenitor cell field by permitting unprecedented resolution of individual cell expression changes within the context of population- or tissue-wide changes. In this article, we provide detailed protocols to dissect mouse epididymal adipose tissue, isolate single adipose tissue-derived cells, and perform fluorescence activated cell sorting (FACS) to enrich for viable Sca1+/CD31-/CD45-/Ter119- APCs. These protocols will allow investigators to prepare high quality APCs suitable for downstream analyses such as single cell RNA sequencing.

Weight Loss Results in Increased Expression of Anti-Inflammatory Protein CRISPLD2 in Mouse Adipose Tissue.

Obesity is a major risk factor for cardiovascular disease, metabolic syndrome, and type 2 diabetes mellitus, whereas weight loss is associated with improved health outcomes. It is therefore important to learn how adipose contraction during weight loss contributes to improved health. It was hypothesized that adipose tissue undergoing weight loss would have a unique transcriptomic profile, expressing specific genes that might improve health. This study conducted anRNA-sequencing analysis of the epididymal adipose tissue of mice fed either a high-fat diet (HFD) or a regular rodent chow diet (RD) ad libitum for 10 weeks versus a cohort of mice fed HFD for the first 5 weeks before being swapped to an RD for the remainder of the study (swapped diet [SWAP]). The swapped diet resulted in weight loss, with a parallel improvement in insulin sensitivity. RNAsequencing revealed several transcriptomic signatures distinct to adipose tissue in SWAP mice, distinguished from both RD and HFD adipose tissue. The analysis found a unique upregulated mRNA that encodes a secreted lipopolysaccharide-binding glycoprotein (CRISPLD2) in adipose tissue. Whereas cellular CRISPLD2 protein levels were unchanged, plasma CRIPSLD2 levels increased in SWAP mice following weight loss and could correlate with insulin sensitivity. Taken together, thesedata demonstrate that CRISPLD2 is a circulating adipokine that may regulate adipocyte remodeling during weight loss.

Feeding of 1-Kestose Induces Glutathione-S-Transferase Expression in Mouse Liver.

Functional food ingredients, including prebiotics, have been increasingly developed for human health. The improvement of the human intestinal environment is one of their main targets. Fructooligosaccarides (FOS) are oligosaccharide fructans that are well studied and commercialized prebiotics. 1-Kestose, one of the components of FOS, is considered to be a key prebiotic component in FOS. However, to our knowledge, no studies have been reported on the physiological efficacy of 1-Kestose regarding its anti-oxidative activity. In the present study, we examined the effects of dietary 1-Kestose on gene expression of antioxidative enzymes in the liver, kidney and epididymal adipose tissue of mice by quantitative RT-PCR (qRT-PCR). We demonstrated that a 1-Kestose-rich diet increased mRNA and enzymatic activity levels of glutathione-S-transferase (GST) in mouse liver. These results suggest the possibility that dietary 1-Kestose as a prebiotic may enhance antioxidative activity in mice.

Effect of biotin supplementation on fatty acid metabolic pathways in 3T3-L1 adipocytes.

Several studies have shown that pharmacological concentrations of biotin decrease serum lipid concentrations and the expression of lipogenic genes. Previous studies on epididymal adipose tissue in mice revealed that 8 weeks of dietary biotin supplementation increased the protein abundance of the active form of AMPK and the inactive forms acetyl CoA carboxylase (ACC)-1 and - 2, and decreased serum free fatty acid concentrations but did not affect lipolysis. These data suggest that pharmacological concentrations of the vitamin might affect fatty acid metabolism. In this work, we investigated the effects of pharmacological biotin concentrations on fatty acid synthesis, oxidation, and uptake in 3T3-L1 adipocytes. Similar to observations in mice, biotin-supplemented 3T3-L1 adipose cells increased the protein abundance of active T172 -AMPK and inactive ACC-1 and -2 forms. No changes were observed in the expression of the transcriptional factor PPARα and carnitine-palmitoyltransferase-1 (CPT-1). Radiolabeled assays indicated a decrease in fatty acid synthesis; an increase in fatty acid oxidation and fatty acid incorporation rate into the lipid fraction between control cells and biotin-supplemented cells. The data revealed an increase in the mRNA abundance of the fatty acid transport proteins Fatp1 and Acsl1 but not Cd36 or Fatp4 mRNA. Furthermore, the abundance of glycerol phosphate acyl transferase-3 protein was increased. Triglyceride content was not affected. Lipid droplet numbers showed an increase and their areas were smaller in the biotin-supplemented group. In conclusion, these data indicate that biotin supplementation causes a decrease in fatty acid synthesis and an increase in its oxidation and uptake. © 2018 BioFactors, 45(2):259-270, 2019.

Some biological reactions of the organism after exposure to nanosecond repetitive pulsed microwaves

White adipose tissue is an important neuroendocrine organ, it can change the activity of the brain through its biologically active substances, and therefore, it can influence functioning of the body. The effects of nanosecond repetitive pulsed microwaves (RPMs) on the brain and epididymal adipose tissue of mice locally was studied (10 days, 4000 pulses per a day, peak power flux density of 1500W/cm2, pulse duration of 100 ns, repetition rates of 6, 13, 16, 22 Hz). The effect of RPM exposure was estimated from the changing of behavioural responses, neuronal activity of brain structures and level of corticosterone in blood serum. The data shows that direct nanosecond RPM irradiation of the brain changes brain activity. The effect is a significant multidirectional behavioural response, changes in the dynamics of general locomotor activity, in the neuronal activation of the hypothalamus and the reticular formation, as well as in the level of corticosterone. Furthermore, direct nanosecond RPM irradiation of the epididymal adipose tissue significantly changed the state of mice. Specifically, the RPMs were able to change the morphometric parameters of the adipose tissue itself, change the content of corticosterone in the blood serum, as well as change the behavioural responses of animals.

Adipose T cell microRNAs influence the T cell expansion, microbiome and macrophage function during obesity

Abstract Obesity is a global health problem that has reached epidemic proportions and the World Health Organization (WHO) estimates 500 million adults are obese. Obesity facilitates the development and progression of metabolic disorder diseases. Extensive evidence suggests that composition of the intestinal microbiota can influence susceptibility to obesity. T helper cells and macrophage in adipose tissue (AT) are strongly linked to the initiation of obesity-associated chronic inflammation. In this study, we investigated how high fat diet (HFD) impacts homeostatic expansion of T cells, adipose T cell microRNAs (miRs), macrophage and the intestinal microbiota during obesity. HFD consumption alters the body weight, fat mass and lean mass of mice as compared with a normal diet (ND). HFD also increases the homeostatic expansion of T cells in the epididymal AT as compared with a ND. Epididymal AT in mice fed a HFD exhibited significant downregulation of miR-10a, miR-125b, and miR-1247 when compared to mice fed a ND. These obesity-induced changes in miRs were validated by RT-PCR analysis. Pathways analysis also validated that downregulated miRs and gene target mRNAs are associated with T cells homeostatic expansion and macrophage function. We also noticed striking changes in microbial composition of firmicutes, bacteriodates, and ruminococeae during consumption of HFD as compared to ND. Taken together, these results indicate that HFD modulates AT miRs and intestinal microbiome to induce T cells homeostatic expansion and changes in macrophage function to sustain inflammation. This study supports a key role of AT miRs in mediating chronic inflammation during HFD induced obesity.

Fish collagen peptide inhibits the adipogenic differentiation of preadipocytes and ameliorates obesity in high fat diet-fed mice

Bioactivities of fish collagen peptide are now being elucidated in diverse biological systems. Here, we investigated the effect of fish collagen peptide on the adipogenic differentiation of 3T3-L1 preadipocytes and in obese mice fed a high fat diet (HFD). Subcritical water-hydrolyzed fish collagen peptide (SWFCP) significantly inhibited lipid accumulation during the differentiation of 3T3-L1 preadipocytes, which was accompanied by decreased expression of CCAAT-enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), and adipocyte protein 2 (aP2) genes, key regulators of differentiation and maintenance of adipocytes. SWFCP was also found to suppress the palmitate-induced accumulation of lipid vacuoles in hepatocytes. Oral administration of SWFCP significantly reduced HFD-induced body weight gain without a significant difference in food intake. Consistent with its effects in 3T3-L1 preadipocytes, SWFCP inhibited the expression of C/EBP-α, PPAR-γ, and aP2 in epididymal adipose tissue of mice fed a HFD, leading to a significant reduction in adipocyte size. Furthermore, SWFCP significantly reduced serum levels of total cholesterol, triglyceride, and low-density lipoprotein, and increased serum high-density lipoprotein. These observations suggest that SWFCP inhibits adipocyte differentiation through a mechanism involving transcriptional repression of the major adipogenic regulators C/EBP-α and PPAR-γ, thereby reducing body weight gain and adipogenesis in an animal model of obesity.

Extended Multiplexing of Tandem Mass Tags (TMT) Labeling Reveals Age and High Fat Diet Specific Proteome Changes in Mouse Epididymal Adipose Tissue

The lack of high-throughput methods to analyze the adipose tissue protein composition limits our understanding of the protein networks responsible for age and diet related metabolic response. We have developed an approach using multiple-dimension liquid chromatography tandem mass spectrometry and extended multiplexing (24 biological samples) with tandem mass tags (TMT) labeling to analyze proteomes of epididymal adipose tissues isolated from mice fed either low or high fat diet for a short or a long-term, and from mice that aged on low versus high fat diets. The peripheral metabolic health (as measured by body weight, adiposity, plasma fasting glucose, insulin, triglycerides, total cholesterol levels, and glucose and insulin tolerance tests) deteriorated with diet and advancing age, with long-term high fat diet exposure being the worst. In response to short-term high fat diet, 43 proteins representing lipid metabolism (e.g. AACS, ACOX1, ACLY) and red-ox pathways (e.g. CPD2, CYP2E, SOD3) were significantly altered (FDR < 10%). Long-term high fat diet significantly altered 55 proteins associated with immune response (e.g. IGTB2, IFIT3, LGALS1) and rennin angiotensin system (e.g. ENPEP, CMA1, CPA3, ANPEP). Age-related changes on low fat diet significantly altered only 18 proteins representing mainly urea cycle (e.g. OTC, ARG1, CPS1), and amino acid biosynthesis (e.g. GMT, AKR1C6). Surprisingly, high fat diet driven age-related changes culminated with alterations in 155 proteins involving primarily the urea cycle (e.g. ARG1, CPS1), immune response/complement activation (e.g. C3, C4b, C8, C9, CFB, CFH, FGA), extracellular remodeling (e.g. EFEMP1, FBN1, FBN2, LTBP4, FERMT2, ECM1, EMILIN2, ITIH3) and apoptosis (e.g. YAP1, HIP1, NDRG1, PRKCD, MUL1) pathways. Using our adipose tissue tailored approach we have identified both age-related and high fat diet specific proteomic signatures highlighting a pronounced involvement of arginine metabolism in response to advancing age, and branched chain amino acid metabolism in early response to high fat feeding. Data are available via ProteomeXchange with identifier PXD005953.

Metformin and resveratrol inhibit Drp1-mediated mitochondrial fission and prevent ER stress-associated NLRP3 inflammasome activation in the adipose tissue of diabetic mice

ObjectiveThis study was designed to investigate the hypothesis that metformin and resveratrol exhibited the same effect on inhibition of NLRP3 inflammasome activation with regulation of AMPK in adipose tissue exposed to high glucose. MethodsTo induce adipose tissue dysfunction, we treated epididymal adipose tissue of mice or differentiated 3T3-L1 adipocytes with high glucose (33 mM) for 24 h. Meanwhile, mice were injected with streptozotocin STZ to induce diabetes and followed by oral administration of metformin (200 mg/kg), resveratrol (50 mg/kg) or ER stress inhibitor TUDCA (50 mg/kg) for 7 days. The effects of metformin and resveratrol on ROS production, mitochondrial fission, ER stress, TXNIP/NLRP3 inflammasome activation, inflammation and apoptosis were observed. ResultsMetformin and resveratrol inhibited ROS-associated mitochondrial fission by upregulating Drp1 phosphorylation (Ser 637) in an AMPK-dependent manner, and then suppressed ER stress indicated by dephosphorylation of IRE1α and eIF2α in the adipose tissue. As a result from suppressing TXNIP/NLRP3 inflammasome activation, metformin and resveratrol inhibited inflammation and reduced cell apoptosis in adipose tissue or adipocytes exposed to high glucose. ConclusionMetformin and resveratrol protected mitochondrial integrity by inhibiting Drp1 activity and prevented NLRP3 inflammasome activation by suppressing ER stress, and thereby protected adipose function from high glucose insult.

Obestatin and Nt8U influence glycerolipid metabolism and PPAR gamma signaling in mice

Obestatin, its N-terminal fragment and the N-terminal fragment analog Nt8U were previously shown to reduce food intake, gain in body weight and triglyceride levels in albino mice. To establish their mode of action, mRNA profiling of the epididymal adipose tissue of mice treated with these peptides were performed. The differential expressions were markedly indicative of their involvement in lipid metabolism. Obestatin showed a significant upregulation of the genes patatin-like phospholipase domain containing 3, diacylglycerol O-acyltransferase 2, monoglyceride lipase, aldo–keto reductase family 1, member 7 which are involved in glycerolipid metabolism. It also upregulated peroxisome proliferator-activated receptor gamma, retinoid X receptor gamma, cluster of differentiation 36, adiponectin, C1Q and collagen domain containing, angiopoietin-like 4, lipoprotein lipase, stearoyl-coenzyme A and desaturase 3 involved in the peroxisome proliferator-activated receptor signaling pathway. Nt8U upregulated genes implicated in the same two pathways but with lesser significance and also upregulated APOL2. The N-terminal fragment though differentially regulated a small subset of the genes differentially regulated by obestatin and Nt8U, no conclusive evidence was obtained as to assign a specific pathway for its mode of action. We hypothesize that reduced food intake brought about by obestatin and Nt8U triggers lipid catabolism. The free fatty acids and lysophosphatidic acid thus produced in turn activates peroxisome proliferator-activated receptor gamma and the genes involved in peroxisome proliferator-activated receptor signaling. All of them together lead to reduction in gain in bodyweight, stored fat and circulating lipids. These results also correlate well with the observed efficacy of the peptides.

Exercise training protects against an acute inflammatory insult in mouse epididymal adipose tissue

Exercise training reduces systemic and adipose tissue inflammation. However, these beneficial effects seem to be largely tied to reductions in adipose tissue mass. The purpose of the present study was to determine if exercise training confers a protective effect against an acute inflammatory challenge. We hypothesized that the induction of inflammatory markers, such as interleukin 6 (IL-6), suppressor of cytokine signaling 3 (SOCS3), and TNF-α by the beta-3 adrenergic agonist CL 316,243 would be reduced in adipose tissue from trained mice and this would be associated with reductions in transient receptor potential cation channel 4 (TRPV4), a protein recently shown to regulate the expression of proinflammatory cytokines. Exercise training (4 wk of treadmill running, 1 h/day, 5 days/wk) increased markers of skeletal muscle mitochondrial content and the induction of PPAR-gamma coactivator 1 alpha in epididymal adipose tissue. The mRNA expression of IL-6, SOCS3, and TNFα were not different in subcutaneous and epididymal adipose tissue from sedentary and trained mice; however, the CL 316,243-mediated induction of these genes was attenuated ∼50% in epididymal adipose tissue from trained mice as were increases in plasma IL-6. The effects of training were not explained by reductions in lipolytic responsiveness, but were associated with decreases in TRPV4 protein content. These results highlight a previously unappreciated anti-inflammatory effect of exercise training on adipose tissue immunometabolism and underscores the value of assessing adipose tissue inflammation in the presence of an inflammatory insult.

Proteome Analysis of Mouse Adipose Tissue and Colon Tissue using a Novel Integrated Data Processing Pipeline

Abstract: Liquid chromatography based mass spectrometry (LC-MS) is a key technology for analyzing highly complex anddynamic proteome samples. With highly accurate and sensitive LC-MS analysis of complex proteome samples, efficient dataprocessing is another critical issue to obtain more information from LC-MS data. A typical proteomic data processing starts wit hprotein database search engine which assigns peptide sequences to MS/MS spectra and finds proteins. Although several searchengines, such as SEQUEST and MASCOT, have been widely used, there is no unique standard way to interpret MS/MS spectraof peptides. Each search engine has pros and cons depending on types of mass spectrometers and physicochemical properties ofpeptides. In this study, we describe a novel data process pipeline which identifies more peptides and proteins by correcting pre-cursor ion mass numbers and unifying multi search engines results. The pipeline utilizes two open-source software, i PE-MMRfor mass number correction, and iProphet to combine several search results. The integrated pipeline identified 25% more pro-teins in mouse epididymal adipose tissue compared with the conventional method. Also the pipeline was validated using controland colitis induced colon tissue. The results of the present study shows that the integrated pipeline can efficiently identifyincreased number of proteins compared to the conventional method which can be a breakthrough in identification of a potentialbiomarker candidate.Key words: iPE-MMR, iProphet, Q-TOF, TPP

Evidence for the role of AMPK in regulating PGC‐1 alpha expression and mitochondrial proteins in mouse epididymal adipose tissue

PGC-1α is a transcriptional co-activator and master regulator of mitochondrial biogenesis. While extensively studied in skeletal and cardiac muscle, recent findings suggest that white adipose tissue PGC-1α plays an important role in regulating glucose homeostasis. The purpose of the present investigation was to evaluate the role of AMPK in regulating PGC-1α and mitochondrial enzymes in mouse epididymal and inguinal subcutaneous adipose tissue. Mitochondrial protein content and norepinephrine and CL 316,243-induced PGC-1α mRNA expression were studied in mouse epididymal and inguinal adipose tissue from wild-type and AMPK β1(-/-) mice. The protein content and phosphorylation of AMPKα was reduced in epididymal adipose tissue from AMPK β1(-/-) compared to WT mice, concomitant with decreases in PGC-1α and mitochondrial marker proteins. Norepinephrine and CL 316,243-mediated induction of PGC-1α were decreased in cultured epididymal adipose tissue from AMPK β1(-/-) relative to WT mice. In inguinal adipose tissue from AMPK β1(-/-) mice, mitochondrial marker protein content and norepinephrine and CL 316,243-mediated increases in PGC-1α were normal despite reductions in the content and phosphorylation of AMPKα. Norepinephrine- and CL 316,243-mediated induction of PGC-1α and mitochondrial protein expression is regulated by AMPK in epididymal, but not inguinal adipose tissue.

Topical application of capsaicin reduces visceral adipose fat by affecting adipokine levels in high‐fat diet‐induced obese mice

Visceral obesity contributes to the development of obesity-related disorders such as diabetes, hyperlipidemia, and fatty liver disease, as well as cardiovascular diseases. In this study, we determined whether topical application of capsaicin can reduce fat accumulation in visceral adipose tissues. We first observed that topical application of 0.075% capsaicin to male mice fed a high-fat diet significantly reduced weight gain and visceral fat. Fat cells were markedly smaller in the mesenteric and epididymal adipose tissues of mice treated with capsaicin cream. The capsaicin treatment also lowered serum levels of fasting glucose, total cholesterol, and triglycerides. Immunoblot analysis and RT-PCR revealed increased expression of adiponectin and other adipokines including peroxisome proliferator-activated receptor (PPAR) α, PPARγ, visfatin, and adipsin, but reduced expression of tumor necrosis factor-α and IL-6. These results indicate that topical application of capsaicin to obese mice limits fat accumulation in adipose tissues and may reduce inflammation and increase insulin sensitivity.

CX3CR1 Deficiency Does Not Influence Trafficking of Adipose Tissue Macrophages in Mice With Diet‐Induced Obesity

Adipose tissue macrophages (ATMs) accumulate in fat during obesity and resemble foam cells in atherosclerotic lesions, suggesting that common mechanisms underlie both inflammatory conditions. CX(3)CR1 and its ligand fractalkine/CX(3)CL1 contribute to macrophage recruitment and inflammation in atherosclerosis, but their role in obesity-induced adipose tissue inflammation is unknown. Therefore, we tested the hypothesis that CX(3)CR1 regulates ATM trafficking to epididymal fat and contributes to the development of adipose tissue inflammation during diet-induced obesity. Cx(3)cl1 and Cx(3)cr1 expression was induced specifically in epididymal fat from mice fed a high-fat diet (HFD). CX(3)CR1 was detected on multiple myeloid cells within epididymal fat from obese mice. To test the requirement of CX(3)CR1 for ATM trafficking and obesity-induced inflammation, Cx(3)cr1(+/GFP) and Cx(3)cr1(GFP/GFP) mice were fed a HFD. Ly-6c(Low) monocytes were reduced in lean Cx(3)cr1(GFP/GFP) mice; however, HFD-induced monocytosis was comparable between strains. Total ATM content, the ratio of type 1 (CD11c(+)) to type 2 (CD206(+)) ATMs, expression of inflammatory markers, and T-cell content were similar in epididymal fat from obese Cx(3)cr1(+/GFP) and Cx(3)cr1(GFP/GFP) mice. Cx(3)cr1 deficiency did not prevent the development of obesity-induced insulin resistance or hepatic steatosis. In summary, our data indicate that CX(3)CR1 is not required for the recruitment or retention of ATMs in epididymal adipose tissue of mice with HFD-induced obesity even though CX(3)CR1 promotes foam cell formation. This highlights an important point of divergence between the mechanisms regulating monocyte trafficking to fat with obesity and those that contribute to foam cell formation in atherogenesis.

The Effect of dietary fatty acids on the recruitment of brown‐like adipocytes in inguinal white adipose tissue

The physiological significance of brown adipose tissue (BAT) in energy metabolism in adult humans has been recently re‐evaluated. The evidence from recent studies indicates a potential of converting white to brown adipocytes in white adipose tissue (WAT). Herein, we explored the regulatory effect of dietary fatty acids on this conversion in WAT. We found that BAT‐specific UCP1 was expressed at a significantly higher level in inguinal adipose tissue (ING) compared to epididymal adipose tissue in mice. High fat diet (HFD) modulated UCP1 expression in BAT and ING in a different manner. After one week of HFD, UCP1 was increased in BAT, but not in ING of mice. However, UCP1 was dramatically decreased after chronic HFD feeding in both tissues. Additionally, we examined the effects of saturated and polyunsaturated fatty acids on the differentiation of brown‐like adipocytes in primary culture of stromal‐vascular (SV) cells from ING of normal mice. Fatty acids were added to SV cell culture either during 8 days of differentiation or after differentiation for 24 hours. In differentiated adipocytes, 24h treatment with palmitate significantly reduced UCP1, while n‐3 fatty acid (EPA) treatment did not change UCP1 expression. However, UCP1 and PGC1α expression was significantly increased in SV cell cultures after 8‐ day EPA treatment. Our data suggests that EPA is capable of inducing the differentiation of inguinal SV cells into brown‐like adipocytes, but failed to induce UCP1 expression in mature white adipocytes. We conclude that HFD or saturated FA reduces UCP1, while EPA has a potential to increase the recruitment of brown‐like adipocytes in inguinal WAT.Grant Funding Source : General Mills Foundation, MN Obesity Consortium