Thermogenic Factors Research Articles

A phytoestrogen secoisolariciresinol diglucoside induces browning of white adipose tissue and activates non-shivering thermogenesis through AMPK pathway

Secoisolariciresinol diglucoside (SDG) is the main phytoestrogen component of flaxseed known as an antioxidant. Current study focused on the effect of SDG in white adipose tissue (WAT) browning. Browning of WAT is considered as a promising treatment strategy for metabolic diseases. To demonstrate the effect of SDG as an inducer of browning, brown adipocyte markers were investigated in inguinal WAT (iWAT) of high fat diet-fed obese mice and genetically obese db/db mice after SDG administration. SDG increased thermogenic factors such as uncoupling protein 1, peroxisome proliferator-activated receptor gamma coactivator 1 alpha and PR domain containing 16 in iWAT and brown adipose tissue (BAT) of mice. Similar results were shown in beige-induced 3T3-L1 adipocytes and primary cultured brown adipocytes. Furthermore, SDG increased factors of mitochondrial biogenesis and activation. We also observed SDG-induced alteration of AMP-activated protein kinase α (AMPKα). As AMPKα is closely related in the regulation of adipogenesis and thermogenesis, we then evaluated the effect of SDG in AMPKα-inhibited conditions. Genetic or chemical inhibition of AMPKα demonstrated that the role of SDG on browning and thermogenesis was dependent on AMPKα signaling. In conclusion, our data suggest SDG as a potential candidate for improvement of obesity and other metabolic disorders.

Gomisin N from Schisandra chinensis Ameliorates Lipid Accumulation and Induces a Brown Fat-Like Phenotype through AMP-Activated Protein Kinase in 3T3-L1 Adipocytes.

Obesity results from an imbalance between energy intake and energy expenditure, in which excess fat is stored as triglycerides (TGs) in white adipocytes. Recent studies have explored the anti-obesity effects of certain edible phytochemicals, which suppress TG accumulation and stimulate a brown adipocyte-like phenotype in white adipocytes. Gomisin N (GN) is an important bioactive component of Schisandra chinensis, a woody plant endemic to Asia. GN has antioxidant, anti-inflammatory and hepatoprotective effects in vivo and in vitro. However, the anti-obesity effects of GN in lipid metabolism and adipocyte browning have not yet been investigated. In the present study, we aimed to determine whether GN suppresses lipid accumulation and regulates energy metabolism, potentially via AMP-activated protein kinase (AMPK), in 3T3-L1 adipocytes. Our findings demonstrate that GN inhibited adipogenesis and lipogenesis in adipocyte differentiation. Also, GN not only increased the expression of thermogenic factors, including uncoupling protein 1 (UCP1), but also enhanced fatty acid oxidation (FAO) in 3T3-L1 cells. Therefore, GN may have a therapeutic benefit as a promising natural agent to combat obesity.

Anti-Obesity Effects of Grateloupia elliptica, a Red Seaweed, in Mice with High-Fat Diet-Induced Obesity via Suppression of Adipogenic Factors in White Adipose Tissue and Increased Thermogenic Factors in Brown Adipose Tissue.

Obesity is a serious metabolic syndrome characterized by high levels of cholesterol, lipids in the blood, and intracellular fat accumulation in adipose tissues. It is known that the suppression of adipogenic protein expression is an effective approach for the treatment of obesity, and regulates fatty acid storage and transportation in adipose tissues. The 60% ethanol extract of Grateloupia elliptica (GEE), a red seaweed from Jeju Island in Korea, was shown to exert anti-adipogenic activity in 3T3-L1 cells and in mice with high-fat diet (HFD)-induced obesity. GEE inhibited intracellular lipid accumulation in 3T3-L1 cells, and significantly reduced expression of adipogenic proteins. In vivo experiments indicated a significant reduction in body weight, as well as white adipose tissue (WAT) weight, including fatty liver, serum triglycerides, total cholesterol, and leptin contents. The expression of the adipogenic proteins, SREBP-1 and PPAR-γ, was significantly decreased by GEE, and the expression of the metabolic regulator protein was increased in WAT. The potential of GEE was shown in WAT, with the downregulation of PPAR-γ and C/EBP-α mRNA; in contrast, in brown adipose tissue (BAT), the thermogenic proteins were increased. Collectively, these research findings suggest the potential of GEE as an effective candidate for the treatment of obesity-related issues via functional foods or pharmaceutical agents.

Ginsenoside Rb1 Induces Beta 3 Adrenergic Receptor-Dependent Lipolysis and Thermogenesis in 3T3-L1 Adipocytes and db/db Mice.

Obesity is constantly rising into a major health threat worldwide. Activation of brown-like transdifferentiation of white adipocytes (browning) has been proposed as a promising molecular target for obesity treatment. In this study, we investigated the effect of ginsenoside Rb1 (Rb1), a saponin derived from Panax ginseng Meyer, on browning. We used 3T3-L1 murine adipocytes and leptin receptor mutated db/db mice. The lipid accumulation, AMP-activated protein kinase alpha (AMPKα)–related pathways, lipolytic and thermogenic factors were measured after Rb treatment in 3T3-L1 adipocytes. Body weight change and lipolysis–thermogenesis factors were investigated in Rb1-treated db/db mice. Beta 3 adrenergic receptor activation (β3AR) changes were measured in Rb1-treated 3T3-L1 cells with or without β3AR inhibitor L748337 co-treatment. As a result, Rb1 treatment decreased lipid droplet size in 3T3-L1 adipocytes. Rb1 also induced phosphorylations of AMPKα pathway and sirtuins. Moreover, lipases and thermogenic factors such as uncoupling protein 1 were increased by Rb1 treatment. Through these results, we could expect that the non-shivering thermogenesis program can be induced by Rb1. In db/db mice, 6-week injection of Rb1 resulted in decreased inguinal white adipose tissue (iWAT) weight associated with shrunken lipid droplets and increased lipolysis and thermogenesis. The thermogenic effect of Rb1 was possibly due to β3AR, as L748337 pre-treatment abolished the effect of Rb1. In conclusion, we suggest Rb1 as a potential lipolytic and thermogenic therapeutic agent which can be used for obesity treatment.

Jiang Gui Fang activated interscapular brown adipose tissue and induced epididymal white adipose tissue browning through the PPARγ/SIRT1-PGC1α pathway.

Gui Zhi Tang, a well-known Chinese herbal formula recorded in the Eastern Han Dynasty, has been widely used to treat exogenous cold for thousands of years. Recent studies have shown that Gui Zhi Tang has the effect of regulating the body temperature. Because of its effect on heat production, protecting vital organs of the body and avoiding damage from the cold environment, Jiang Gui Fang (JG) was obtained from the Department of Traditional Chinese Medicine at the General Hospital of Northern Theatre Command where it has been used clinically for many years and has exhibited favourable efficacy. Based on research on Gui Zhi Tang, the principles of traditional Chinese medicine and survey of a large number of studies, this empirical formula was developed. The composition of JG included Dried ginger, Cassia twig, and Liquorice in Gui Zhi Tang, which play a major role in the treatment of exogenous cold, and combined these components with other Chinese medicines, such as Pueraria, Spatholobus, Acanthopanacis cortex, Evodiae fructus, and Codonopsis pilosula. To promote the core body temperature and prevent invasion of the major organs from the cold environment, we studied the effect of JG on the core body temperature of mice and then explored its regulation of interscapular brown adipose tissue (iBAT) and epididymal white adipose tissue (eWAT) and the possible mechanism. Finally, we determined the phytochemical composition of JG that plays a role in heat production. In vivo study, we performed a 4-week treatment of JG in acute cold environment at -20 °C and chronic cold exposure at 4 °C. The core temperature, adipose tissue weight, serum parameters, and morphological observation of adipocytes, liver and kidney were measured. Then we investigated the expression levels of adipogenic factors, thermogenic factors and lipoprotein. In vitro, we determined the lipid droplet content, ATP content, and the maximum oxygen consumption of mitochondria. JG treatment promoted core temperature, inhibited eWAT weight, protected liver, and reduced glucose and lipids in Kunming (KM) mice. JG also increased the expression of BAT-associated thermogenic factors, including uncoupling protein 1 (UCP1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC1α). The levels of the lipogenic factor peroxisome proliferate-activator receptor gamma (PPARγ) and the lipolytic protein hormone-sensitive triglyceride lipase (HSL) in eWAT were elevated. The results of H&E and immunohistochemistry showed that JG significantly reduced the size of iBAT and eWAT and increased the content of UCP1. In vitro, JG reduced the content of lipid droplets and ATP in brown fat cells. The maximum oxygen consumption capacity of mitochondria and the expression levels of UCP1, PGC1α and silent mating type information regulation 2 homologue 1 (SIRT1) were enhanced after JG treatment. In vivo and in vitro studies, the results demonstrated that JG obviously increased the core temperature of mice by activating iBAT and inducing eWAT browning, which proved the mechanism is closely related to the PPARγ/SIRT1- PGC1α pathway. In this paper, we will provide a reference for further study of iBAT activation and eWAT browning.

Bitter Orange (Citrus aurantium Linné) Improves Obesity by Regulating Adipogenesis and Thermogenesis through AMPK Activation.

Obesity is a global health threat. Herein, we evaluated the underlying mechanism of anti-obese features of bitter orange (Citrus aurantium Linné, CA). Eight-week-administration of CA in high fat diet-induced obese C57BL/6 mice resulted in a significant decrease of body weight, adipose tissue weight and serum cholesterol. In further in vitro studies, we observed decreased lipid droplets in CA-treated 3T3-L1 adipocytes. Suppressed peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein alpha indicated CA-inhibited adipogenesis. Moreover, CA-treated primary cultured brown adipocytes displayed increased differentiation associated with elevation of thermogenic factors including uncoupling protein 1 and PPARγ coactivator 1 alpha as well. The effects of CA in both adipocytes were abolished in AMP-activated protein kinase alpha (AMPKα)-suppressed environments, suggesting the anti-adipogenic and pro-thermogenic actions of CA were dependent on AMPKα pathway. In conclusion, our results suggest CA as a potential anti-obese agent which regulates adipogenesis and thermogenesis via AMPKα.

Ishige okamurae Extract Ameliorates the Hyperglycemia and Body Weight Gain of db/db Mice through Regulation of the PI3K/Akt Pathway and Thermogenic Factors by FGF21.

Type 2 diabetes mellitus and related metabolic disorders, such as dyslipidemia, present increasing challenges to health worldwide, as a result of urbanization, the increasing prevalence of obesity, poor lifestyle, and other stress-related factors. Ishige okamurae extract (IOE) is known to be effective at lowering blood glucose and ameliorating metabolic disease. However, detailed mechanisms for these effects have yet to be elucidated. Here, we show that IOE ameliorates substrate (IRS)/ phosphatidylinositol 3-kinase (PI3K)/Akt pathway and increasing glucose transporter 4 (GLUT4) expression in skeletal muscle and white adipose tissue (WAT). We also demonstrate that IOE increases the expression of fibroblast growth factor (FGF)21, a regulator of glucose and energy metabolism in muscle and WAT. In addition, IOE administration increased peroxisome proliferator-activated receptor γ coactivator 1α expression, which regulates expression of the key thermogenic molecule uncoupling protein 1 in WAT. Thus, the effects of IOE to ameliorate hyperglycemia and adiposity may be mediated through FGF21 activating insulin signaling and increasing the expression of GLUT4 and pro-thermogenic factors.

Stem Cell‐Based Modelling of Brown Adipogenesis Using Hypothermal Conditions

In vivo cold exposure is the main stimulus to activate the unique mitochondrial uncoupling protein (UCP)1, known for mediating heat production in brown and beige adipocytes. In vitro, UCP1 adipogenic response under hypothermic conditions requires an extended evaluation in order to be comparable to an in vivo cellular function. We have developed a new in vitro culture system to induce adipogenic browning in bone marrow (BM) derived mesenchymal stem cells (MSC), using exposure to reduced temperature during differentiation. Incubation at 32°C instead of 37°C over the course of the culture treatment was seen to promote brown adipogenesis with increased adipocyte response and upregulation of adipogenic and thermogenic factors including UCP1. Adipocytes differentiated under hypothermic conditions displayed enhanced uncoupled respiration and metabolic adaptation, as well as significant durable changes in cellular and molecular features. These results suggest that MSC available from accessible tissue sources can be differentiated in vitro using cold temperature conditions to favor the appearance of functional beige‐like adipocytes. This cell‐based model represents a new valuable tool to screen for pro‐browning factors in vitro and elucidate the mechanism of metabolic adaptation relevant to the browning process.Support or Funding InformationThis work was funded by the EU‐CASCADE fellowship scheme funded by the EU's 7th FP PCOFUND‐GA‐2012‐600181 (K.V.), CONACyT, Mexico (H.A.L.L.), and received support from The Cardiometabolic Disease Research Foundation (Los Angeles, USA) and the Biotechnology and Biological Sciences Research Council (BBSRC, Multidisciplinary Super Resolution Microscopy Facility grant BB/L013827/1).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Administration of eicosapentaenoic and docosahexaenoic acids may improve the remodeling and browning in subcutaneous white adipose tissue and thermogenic markers in brown adipose tissue in mice

The role of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in browning and thermogenesis has not been fully elucidated. Thus, we meant to evaluate the effect of EPA and DHA, administered alone or combined, with the activation of browning markers in subcutaneous white adipose tissue (sWAT), and thermogenic markers in brown adipose tissue (BAT). C57BL/6 adult male mice received a control diet or a high-fructose diet (HFru) for eight weeks, but after the first three weeks, HFru was divided into new groups: HFru, HFru + EPA, HFru + DHA, and HFru-EPA + DHA. EPA and DHA diminished adipocyte hypertrophy, recovered markers of browning in sWAT and thermogenic factors in the BAT, and improved gene expressions linked with mitochondrial biogenesis and lipid metabolism. Importantly, EPA and DHA administrated alone showed stronger results than the combination of EPA + DHA. The results suggest that EPA and DHA might be useful as adjuvant strategies to treat metabolic-associated disorders.

Platycodin D, a novel activator of AMP-activated protein kinase, attenuates obesity in db/db mice via regulation of adipogenesis and thermogenesis

BackgroundPlatycodi Radix (root of Platycodon grandiflorum) and its active compound platycodin D (PD) has been previously shown to possess anti-obesity properties, but the underlying mechanisms remain poorly understood. PurposeThe present study was aimed to evaluate the anti-obese effect of PD and reveal its mechanism of action. Study Design/MethodsGenetically obese db/db mice were orally treated with PD for 4 weeks, and body weight gain, adipose tissue weight, serum parameters were measured. Then, assays on adipogenic factors, thermogenic factors, and AMP-activated protein kinase (AMPK) pathway were performed in PD-treated 3T3-L1 murine adipocytes, human adipose-derived mesenchymal stem cells (hAMSCs), and primary cultured brown adipocytes. ResultsPD treatment attenuated body weight gain, suppressed white adipose tissue weight and improved obesity-related serum parameters in db/db mice. Two major adipogenic factors, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) were decreased by PD treatment in WAT of db/db mice, 3T3-L1 adipocytes and hAMSCs. In BAT of db/db mice and primary cultured brown adipocytes, PD treatment elevated the expressions of uncoupled protein 1 (UCP1) and peroxisome proliferator-activated receptor γ coactivator 1 α (PCG1α), the key regulators of BAT-associated thermogenesis. In addition, PD activated AMPKα both in vivo and in vitro. However, when AMPK was inhibited by compound C, PD treatment failed to suppress adipogenic factors and increase thermogenic factors. ConclusionsPD improved obesity in db/db mice by AMPK-associated decrease of adipogenic markers including PPARγ and C/EBPα. PD increased thermogenic factors such as UCP1 and PGC1α in db/db mice and primary cultured brown adipocytes. AMPK inhibition nullified the effects of PD, suggesting its anti-adipogenic and thermogenic actions were dependent on AMPK pathway activation.

Low temperature exposure induces browning of bone marrow stem cell derived adipocytes in vitro

Brown and beige adipocytes are characterised as expressing the unique mitochondrial uncoupling protein (UCP)1 for which the primary stimulus in vivo is cold exposure. The extent to which cold-induced UCP1 activation can also be achieved in vitro, and therefore perform a comparable cellular function, is unknown. We report an in vitro model to induce adipocyte browning using bone marrow (BM) derived mesenchymal stem cells (MSC), which relies on differentiation at 32 °C instead of 37 °C. The low temperature promoted browning in adipogenic cultures, with increased adipocyte differentiation and upregulation of adipogenic and thermogenic factors, especially UCP1. Cells exhibited enhanced uncoupled respiration and metabolic adaptation. Cold-exposed differentiated cells showed a marked translocation of leptin to adipocyte nuclei, suggesting a previously unknown role for leptin in the browning process. These results indicate that BM-MSC can be driven to forming beige-like adipocytes in vitro by exposure to a reduced temperature. This in vitro model will provide a powerful tool to elucidate the precise role of leptin and related hormones in hitherto functions in the browning process.

Vanillic acid attenuates obesity via activation of the AMPK pathway and thermogenic factors in vivo and in vitro.

Energy expenditure is a target gaining recent interest for obesity treatment. The antiobesity effect of vanillic acid (VA), a well-known flavoring agent, was investigated in vivo and in vitro. High-fat diet (HFD)-induced obese mice and genetically obese db/db mice showed significantly decreased body weights after VA administration. Two major adipogenic markers, peroxisome proliferator activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), were reduced while the key factor of energy metabolism, AMPKα, was increased in the white adipose tissue and liver tissue of VA-treated mice. Furthermore, VA inhibited lipid accumulation and reduced hepatotoxic/inflammatory markers in liver tissues of mice and HepG2 hepatocytes. VA treatment also decreased differentiation of 3T3-L1 adipocytes by regulating adipogenic factors including PPARγ and C/EBPα. AMPKα small interfering RNA was used to examine whether AMPK was associated with the actions of VA. In AMPKα-nulled 3T3-L1 cells, the inhibitory action of VA on PPARγ and C/EBPα was attenuated. Furthermore, in brown adipose tissues of mice and primary cultured brown adipocytes, VA increased mitochondria- and thermogenesis-related factors such as uncoupling protein 1 and PPARγ-coactivator 1-α. Taken together, our results suggest that VA has potential as an AMPKα- and thermogenesis-activating antiobesity agent.-Jung, Y., Park, J., Kim, H.-L., Sim, J.-E., Youn, D.-H., Kang, J., Lim, S., Jeong, M.-Y., Yang, W. M., Lee, S.-G., Ahn, K. S., Um, J.-Y. Vanillic acid attenuates obesity via activation of the AMPK pathway and thermogenic factors in vivo and in vitro.

Prior Repeated Stress Attenuates Cold-Induced Immunomodulation Associated with "Browning" in Mesenteric Fat of Rats.

Continuous exposure to cold leads to activation of adaptive thermogenesis in brown adipose tissue but also to induction of brown/beige cell phenotype in white adipose tissue. The aim of this work was to investigate whether prior exposure to immobilization (IMO) stress may affect immune response associated with adipocyte "browning" in mesenteric adipose tissue (mWAT). In the first experiment, Sprague-Dawley rats were exposed to acute (3h) or prolonged (7days) cold exposure (4±1°C). 7-day cold stimulated gene expression of uncoupling protein 1 and other "browning"-associated factors. In the second experiment, rats were immobilized for 7days (2h daily) followed by exposure to continuous cold for 1 or 7days. Prior IMO exaggerated cold-induced sympathetic response manifested by elevated tyrosine hydroxylase (TH) protein and norepinephrine in mWAT. Induction of non-sympathetic catecholamine production demonstrated by elevated TH and PNMT (phenylethanolamine N-methyltransferase) mRNAs was observed after 7-day cold; however, prior IMO attenuated this response. 7-day cold-induced gene expression of anti-inflammatory mediators (IL-4, IL-13, IL-10, adiponectin), markers of M2 macrophages (Arg1, Retnlα), and eosinophil-associated molecules (eotaxin, IL-5), while inhibited expression of pro-inflammatory cytokines (IFNγ, IL-1b, IL-6, IL-17) and monocytes (MCP-1, Ly6C). This immune response was accompanied by elevated expression of uncoupling protein-1 and other thermogenic factors. Rats exposed to prior IMO exhibited inhibition of cold-induced immune and "browning"-related expression pattern. Overall, we demonstrated that 7-day cold-induced browning"-associated changes in rat mWAT, while prior history of repeated stress prevented this response.

Brown-adipose-tissue macrophages control tissue innervation and homeostatic energy expenditure.

Tissue macrophages provide immune defense and contribute to establishment and maintenance of tissue homeostasis. Here we used constitutive and inducible mutagenesis to delete the nuclear transcription regulator methyl-CpG binding protein 2 (Mecp2) in defined tissue macrophages. Animals lacking the Rett syndrome-associated gene in macrophages did not show signs of neurodevelopmental disorder, but displayed spontaneous obesity, which could be linked to impaired brown adipose tissue (BAT) function. Specifically, mutagenesis of a BAT-resident CX3CR1+ macrophage subpopulation compromised homeostatic, though not acute cold-induced thermogenesis. Mechanistically, BAT malfunction of pre-obese mice harboring mutant macrophages was associated with decreased sympathetic innervation and local norepinephrine titers, resulting in reduced adipocyte expression of thermogenic factors. Mutant macrophages over-expressed PlexinA4, which might contribute to the phenotype by repulsion of Sema6A-expressing sympathetic axons. Collectively, we report a previously unappreciated homeostatic role of macrophages in the control of tissue innervation, disruption of which in BAT results in metabolic imbalance.

Effects of cold sensitivity in the extremities on circulating adiponectin levels and metabolic syndrome in women

BackgroundIn adipose tissues, adipokine levels, including adiponectin and leptin, are involved in insulin sensitivity and are reciprocally induced by cold temperature stress. Thermogenic response in the extremities (hands and feet) against cold stress can be negatively related to fat mass accumulation, particularly in the abdomen. However, the relationship between the sensation of cold in the extremities and circulating levels of adipokines is not fully understood. Here, we investigated whether adipokine levels are associated with cold hypersensitivity in the hands and feet (CHHF), independent of body mass, and whether the CHHF is related to metabolic syndrome (MS).MethodsAssociations of the CHHF with serum levels of adipokines and MS risk were evaluated in 1021 Koreans (372 men and 649 women), using a linear regression model while controlling for thermogenic factors and a logistic regression model, respectively.ResultsThe adiponectin levels were positively associated with the CHHF, particularly in women, irrespective of thermogenic factors, including body mass index (β = 1.23 μg/mL, 95% confidence interval [1.04–1.45]). Logistic regression analysis for MS risk via the CHHF showed that there was a significant inverse association in women (odds ratio = 0.449, 95% confidence interval [0.273–0.737]).ConclusionsIn summary, our founding indicated that the CHHF could induce increased levels of circulating adiponectin and in turn reduce the MS risk in women. Despite complaints of feeling cold, these women could be at lower risk of cardiovascular disease.

Browning and Graying: Novel Transcriptional Regulators of Brown and Beige Fat Tissues and Aging.

Obesity represents a major risk factor for the development of a number of metabolic disorders, including cardiovascular disease and type 2 diabetes. Since the discovery that brown and beige fat cells exist in adult humans and contribute to energy expenditure, increasing interest has been devoted to the understanding of the molecular switches turning on calorie utilization. It has been reported that the ability of thermogenic tissues to burn energy declines during aging, possibly contributing to the development of metabolic dysfunction late in life. This review will focus on the recently identified transcriptional modulators of brown and beige cells and will discuss the potential impact of some of these thermogenic factors on age-associated metabolic disorders.

PPAR-α agonist elicits metabolically active brown adipocytes and weight loss in diet-induced obese mice.

Obesity is considered a public health problem worldwide. Fenofibrate, a selective peroxisome proliferator-activated receptor α (PPAR-α) agonist, elicits weight loss in animal models. This study aimed to examine the effects of fenofibrate on energy expenditure, body mass (BM) and gene expression of thermogenic factors in brown adipose tissue of diet-induced obese mice. Male C57BL/6 mice were fed a standard chow (SC; 10% lipids) diet or a high-fat (HF; 50% lipids) diet for 10 weeks. Afterwards, groups were subdivided as SC, SC-F, HF and HF-F (n = 10, each). Treatment with fenofibrate (100 mg kg(-1) BM mixed into the diet) lasted 5 weeks. Treated groups had reduced final BM compared with their counterparts (p < 0·05), explained by the increase in energy expenditure, CO2 production and O2 consumption after treatment with fenofibrate (p < 0·05). Similarly, genes involved in thermogenesis as PPAR-α, PPAR-γ coactivator 1α, nuclear respiratory factor 1, mitochondrial transcription factor A (Tfam), PR domain containing 16 (PRDM16), β-3 adrenergic receptor (β3-AR), bone morphogenetic protein 8B and uncoupling protein 1 were significantly expressed in brown adipocytes after the treatment (p < 0·05). All observations ensure that selective PPAR-α agonist can induce thermogenesis by increasing energy expenditure and enhancing the expression of genes involved in the thermogenic pathway. These results suggest fenofibrate as a coadjutant drug for the treatment of obesity.

Maternal Low Protein Diet Reduces Birth Weight And Increases Brown Adipose Tissue UCP‐1 and FNDC5 Gene Expression in Male Neonatal Sprague‐Dawley Rats

Brown adipose tissue (BAT) plays an important role in regulating body weight (BW) by modifying thermogenesis. Maternal low protein (LP) diets reduce offspring birth weight. Increased BAT thermogenesis in utero may be one mechanism for the lower BW. However, whether maternal LP nutrition alters BAT thermogenesis and BW of offspring in-utero is not yet known. We fed obese-prone Sprague-Dawley dams 8% low protein (LP) or 20% normal protein (NP) diets for 3 weeks prior to breeding and through pregnancy. BW and gene expression of interscapular BAT (iBAT) thermogenic markers were measured in male fetal (gestation day 18) and neonatal (day 0 or 1) offspring. BW of neonatal LP males was lower than NP males but no difference was observed in females. Gene expression of thermogenic factors UCP-1 and UCP-3 and transcription factors PRDM16 and PPARa in iBAT were 2- to 6-fold greater in LP than NP male neonatal offspring. FNDC5, a precursor of irisin and activator of thermogenesis, was expressed 2-fold greater in neonatal LP iBAT than NP males. However, fetal iBAT UCP-1, PRDM16, PPARa and irisin mRNA did not differ between LP and NP groups. Maternal LP diet had no effects on placental irisin and UCP-2 expression. These results suggest that prenatal protein restriction increases the risk for low BW through mechanisms affecting full-term offspring iBAT thermogenesis but not greatly altering fetal iBAT or placental thermogenesis. This work was supported by USDA Agricultural Research Service Project #3062-51000-052-00D.

Oleoylethanolamide enhances β-adrenergic-mediated thermogenesis and white-to-brown adipocyte phenotype in epididymal white adipose tissue in rat

β-adrenergic receptor activation promotes brown adipose tissue (BAT) β-oxidation and thermogenesis by burning fatty acids during uncoupling respiration. Oleoylethanolamide (OEA) can inhibit feeding and stimulate lipolysis by activating peroxisome proliferator-activating receptor-α (PPARα) in white adipose tissue (WAT). Here we explore whether PPARα activation potentiates the effect of β3-adrenergic stimulation on energy balance mediated by the respective agonists OEA and CL316243. The effect of this pharmacological association on feeding, thermogenesis, β-oxidation, and lipid and cholesterol metabolism in epididymal (e)WAT was monitored. CL316243 (1 mg/kg) and OEA (5 mg/kg) co-administration over 6 days enhanced the reduction of both food intake and body weight gain, increased the energy expenditure and reduced the respiratory quotient (VCO2/VO2). This negative energy balance agreed with decreased fat mass and increased BAT weight and temperature, as well as with lowered plasma levels of triglycerides, cholesterol, nonessential fatty acids (NEFAs), and the adipokines leptin and TNF-α. Regarding eWAT, CL316243 and OEA treatment elevated levels of the thermogenic factors PPARα and UCP1, reduced p38-MAPK phosphorylation, and promoted brown-like features in the white adipocytes: the mitochondrial (Cox4i1, Cox4i2) and BAT (Fgf21, Prdm16) genes were overexpressed in eWAT. The enhancement of the fatty-acid β-oxidation factors Cpt1b and Acox1 in eWAT was accompanied by an upregulation of de novo lipogenesis and reduced expression of the unsaturated-fatty-acid-synthesis enzyme gene, Scd1. We propose that the combination of β-adrenergic and PPARα receptor agonists promotes therapeutic adipocyte remodelling in eWAT, and therefore has a potential clinical utility in the treatment of obesity.

BMP8B Increases Brown Adipose Tissue Thermogenesis through Both Central and Peripheral Actions

SummaryThermogenesis in brown adipose tissue (BAT) is fundamental to energy balance and is also relevant for humans. Bone morphogenetic proteins (BMPs) regulate adipogenesis, and, here, we describe a role for BMP8B in the direct regulation of thermogenesis. BMP8B is induced by nutritional and thermogenic factors in mature BAT, increasing the response to noradrenaline through enhanced p38MAPK/CREB signaling and increased lipase activity. Bmp8b−/− mice exhibit impaired thermogenesis and reduced metabolic rate, causing weight gain despite hypophagia. BMP8B is also expressed in the hypothalamus, and Bmp8b−/− mice display altered neuropeptide levels and reduced phosphorylation of AMP-activated protein kinase (AMPK), indicating an anorexigenic state. Central BMP8B treatment increased sympathetic activation of BAT, dependent on the status of AMPK in key hypothalamic nuclei. Our results indicate that BMP8B is a thermogenic protein that regulates energy balance in partnership with hypothalamic AMPK. BMP8B may offer a mechanism to specifically increase energy dissipation by BAT.