Extracellular thiamine concentration influences thermogenic competency of differentiating neck area-derived human adipocytes.

Introduction: Brown adipose tissue (BAT) dissipates energy in the form of heat majorly via the mitochondrial uncoupling protein 1 (UCP1). The activation of BAT, which is enriched in the neck area and contains brown and beige adipocytes in humans, was considered as a potential therapeutic target to treat obesity. Therefore, finding novel agents that can stimulate the differentiation and recruitment of brown or beige thermogenic adipocytes are important subjects for investigation. The current study investigated how the availability of extracellular thiamine (vitamin B1), an essential cofactor of mitochondrial enzyme complexes that catalyze key steps in the catabolism of nutrients, affects the expression of thermogenic marker genes and proteins and subsequent functional parameters during ex vivo adipocyte differentiation. Methods: We differentiated primary human adipogenic progenitors that were cultivated from subcutaneous (SC) or deep neck (DN) adipose tissues in the presence of gradually increasing thiamine concentrations during their 14-day differentiation program. mRNA and protein expression of thermogenic genes were analyzed by RT-qPCR and western blot, respectively. Cellular respiration including stimulated maximal and proton-leak respiration was measured by Seahorse analysis. Results: Higher thiamine levels resulted in increased expression of thiamine transporter 1 and 2 both at mRNA and protein levels in human neck area-derived adipocytes. Gradually increasing concentrations of thiamine led to increased basal, cAMP-stimulated, and proton-leak respiration along with elevated mitochondrial biogenesis of the differentiated adipocytes. The extracellular thiamine availability during adipogenesis determined the expression levels of UCP1, PGC1a, CKMT2, and other browning-related genes and proteins in primary SC and DN-derived adipocytes in a concentration-dependent manner. Providing abundant amounts of thiamine further increased the thermogenic competency of the adipocytes. Discussion: Case studies in humans reported that thiamine deficiency was found in patients with type 2 diabetes and obesity. Our study raises the possibility of a novel strategy with long-term thiamine supplementation, which can enhance the thermogenic competency of differentiating neck area-derived adipocytes for preventing or combating obesity.

Adverse bioenergetic effects of N-acyl amino acids in human adipocytes overshadow beneficial mitochondrial uncoupling.

OBJECTIVE: Enhancing energy turnover via uncoupled mitochondrial respiration in adipose tissue has great potential to improve human obesity and other metabolic complications. However, the amount of human brown adipose tissue and its uncoupling protein 1 (UCP1) is low in obese patients. Recently, a class of endogenous molecules, N-acyl amino acids (NAAs), was identified as mitochondrial uncouplers in murine adipocytes, presumably acting via the adenine nucleotide translocator (ANT). Given the translational potential, we investigated the bioenergetic effects of NAAs in human adipocytes, characterizing beneficial and adverse effects, dose ranges, amino acid derivatives and underlying mechanisms. METHOD: NAAs with neutral (phenylalanine, leucine, isoleucine) and polar (lysine) residues were synthetized and assessed in intact and permeabilized human adipocytes using plate-based respirometry. The Seahorse technology was applied to measure bioenergetic parameters, dose-dependency, interference with UCP1 and adenine nucleotide translocase (ANT) activity, as well as differences to the established chemical uncouplers niclosamide ethanolamine (NEN) and 2,4-dinitrophenol (DNP). RESULT: NAAs with neutral amino acid residues potently induce uncoupled respiration in human adipocytes in a dose-dependent manner, even in the presence of the UCP1-inhibitor guanosine diphosphate (GDP) and the ANT-inhibitor carboxyatractylate (CAT). However, neutral NAAs significantly reduce maximal oxidation rates, mitochondrial ATP-production, coupling efficiency and reduce adipocyte viability at concentrations above 25 µM. The in vitro therapeutic index (using induced proton leak and viability as determinants) of NAAs is lower than that of NEN and DNP. CONCLUSION: NAAs are potent mitochondrial uncouplers in human adipocytes, independent of UCP1 and ANT. However, previously unnoticed adverse effects harm adipocyte functionality, reduce the therapeutic index of NAAs in vitro and therefore question their suitability as anti-obesity agents without further chemical modifications.

Aurantio-obtusin ameliorates obesity by activating PPARα-dependent mitochondrial thermogenesis in brown adipose tissues.

Obesity contributes to the progression of various chronic diseases, and shortens life expectancy. With abundant mitochondria, brown adipose tissue (BAT) dissipates energy through heat to limit weight gain and metabolic dysfunction in obesity. Our previous studies have shown that aurantio-obtusin (AO), a bioactive ingredient in Chinese traditional medicine Cassiae semen significantly improves hepatic lipid metabolism in a steatotic mouse model. In the current study we investigated the effects of AO on lipid metabolism in the BAT of diet-induced obesity mice and in oleic acid and palmitic acid (OAPA)-stimulated primary mature BAT adipocytes. Obese mice were established by feeding a HFHS diet for 4 weeks, and then administered AO (10 mg/kg, i.g.) for another 4 weeks. We showed that AO administration significantly increased the weight of BAT and accelerated energy expenditure to protect the weight increase in the obese mice. Using RNA sequencing and molecular biology analysis we found that AO significantly enhanced mitochondrial metabolism and UCP1 expression by activating PPARα both in vivo and in vitro in the primary BAT adipocytes. Interestingly, AO administration did not improve metabolic dysfunction in the liver and white adipose tissue of obese mice after interscapular BAT excision. We demonstrated that low temperature, a trigger of BAT thermogenesis, was not a decisive factor for AO to stimulate the growth and activation of BATs. This study uncovers a regulatory network of AO in activating BAT-dependent lipid consumption and brings up a new avenue for the pharmaceutical intervention in obesity and related comorbidities.

Effect of oral cannabis administration on the fat depots of obese and streptozotocin-induced diabetic rats.

The prevalence of obesity and insulin-resistance is on the rise, globally. Cannabis have been shown to have anti-diabetic/obesity properties, however, the effect mediated at various fat depots remains to be clarified. The aim of this study was to (1) investigate the anti-diabetic property of an oral cannabis administration in an obese and streptozotocin-induced diabetic rat model and (2) to determine and compare the effect mediated at the peritoneal and intramuscular fat level. Cannabis concentration of 1.25 mg/kg body weight (relative to THC content) was effective in reversing insulin-resistance in the rat model, unlike the other higher cannabinoid concentrations. At the peritoneal fat level, gene expression of fat beigeing markers, namely Cidea and UCP1, were significantly increased compared to the untreated control. At the intramuscular fat level, on the other hand, CE1.25 treatment did not promote fat beigeing but instead significantly increased mitochondrial activity, relative to the untreated control. Therefore, these findings indicate that the mechanism of action of oral cannabis administration, where glucose and lipid homeostasis is restored, is not only dependent on the dosage but also on the type of fat depot investigated.

Effect of postbiotics derived from kefir lactic acid bacteria-mediated bioconversion of citrus pomace extract and whey on high-fat diet-induced obesity and gut dysbiosis.

The objective of this study was to develop a highly bioactive postbiotic for weight management by bioconversion of whey (WHE) and polyphenol-rich citrus pomace extract (CPX) using kefir lactic acid bacteria (LAB). WHE and CPX bioconverted by kefir LAB (CPB) were fed to C57BL/6J mice on high-fat diets for five weeks and compared with oral administrations of saline (CON), WHE, CPX, and kefir LAB. Hesperetin, a potential therapeutic agent for obesity, was increased in the CPB after bioconversion from an inactive precursor. Compared with the CON group, the CPB group showed significantly reduced body weight gain, adipose tissue weight/body weight ratio, hypertriglyceridemia, and adipocyte diameter along with increased gene expression related to energy expenditure in adipose tissue (p < 0.05). Interestingly, the abundance of gut microbiota related to butyrate production was significantly altered in the CPB group compared with the CON group. There was a significant correlation between obesogenic biomarkers and the abundance of butyrate-producing and obesogenic gut microbiota. In conclusion, kefir LAB-derived bioconversion of WHE and CPX may be effective in combating obesity and obesity-related diseases.

Low-dose lithium supplementation promotes adipose tissue browning and sarco(endo)plasmic reticulum Ca2+ ATPase uncoupling in muscle.

Sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) uncoupling in skeletal muscle and mitochondrial uncoupling via uncoupling protein 1 (UCP1) in brown/beige adipose tissue are two mechanisms implicated in energy expenditure. Here, we investigated the effects of glycogen synthase kinase 3 (GSK3) inhibition via lithium chloride (LiCl) treatment on SERCA uncoupling in skeletal muscle and UCP1 expression in adipose. C2C12 and 3T3-L1 cells treated with LiCl had increased SERCA uncoupling and UCP1 protein levels, respectively, ultimately raising cellular respiration; however, this was only observed when LiCl treatment occurred throughout differentiation. In vivo, LiCl treatment (10 mg/kg/day) increased food intake in chow-fed diet and high-fat diet (HFD; 60% kcal)-fed male mice without increasing body mass-a result attributed to elevated daily energy expenditure. In soleus muscle, we determined that LiCl treatment promoted SERCA uncoupling via increased expression of SERCA uncouplers, sarcolipin and/or neuronatin, under chow-fed and HFD-fed conditions. We attribute these effects to the GSK3 inhibition observed with LiCl treatment as partial muscle-specific GSK3 knockdown produced similar effects. In adipose, LiCl treatment inhibited GSK3 in inguinal white adipose tissue (iWAT) but not in brown adipose tissue under chow-fed conditions, which led to an increase in UCP1 in iWAT and a beiging-like effect with a multilocular phenotype. We did not observe this beiging-like effect and increase in UCP1 in mice fed a HFD, as LiCl could not overcome the ensuing overactivation of GSK3. Nonetheless, our study establishes novel regulatory links between GSK3 and SERCA uncoupling in muscle and GSK3 and UCP1 and beiging in iWAT.

Baicalein modulates mitochondrial function by upregulating mitochondrial uncoupling protein-1 (UCP1) expression in brown adipocytes, cytotoxicity, and computational studies.

BACKGROUND: Obesity, fatty liver, type 2 diabetes, and Non-alcoholic fatty liver disease (NAFLD) are all metabolic diseases caused by excess food consumption. Existing drug molecules had negative side effects and caused other diseases to develop (Orlistat causes angioedema, and menstrual irregularities; megestrol acetate causes hypertension, and insomnia). By enhancing lipid consumption and increasing nonshivering thermogenesis, targeting mitochondrial uncoupling protein-1 (UCP1) expression in adipocytes could be an auspicious treatment strategy against obesity or metabolic disorders associated with obesity. METHODS: We used previously produced UCP1-A-GFP reporter cell lines in this investigation to find new pharmacological compounds against obesity or metabolic syndrome, which we then tested in cellular analysis, cytotoxicity, mitochondrial function, mitochondrial DNA quantification, mitochondrial ATP production, and in-silico models. RESULTS: Baicalein was discovered to play a critical role in obesity prevention via altering mitochondrial function. Baicalein lowers ATP generation while increasing considerable UCP1 gene expression in brown adipocytes. As a result, cellular thermogenesis is boosted. The HEK293T cell line is harmless by baicalein. The investigation by the in-silico study revealed drug-protein interaction and UCP1 binding. Thus, our research clarifies baicalein's therapeutic role in metabolic and obesity-related illnesses via modulating mitochondrial activity (Supplementary Fig. 2). CONCLUSIONS: Further studies are required in both murine and human models to understand the full mechanism of action by mitochondrial modulation. Drug development investigation also requires to development of a precise formulation.

Improved oral nutraceutical-based intervention for the management of obesity: pterostilbene-loaded chitosan nanoparticles.

Aim: To formulate and assess the oral anti-obesity effect of polymeric-based pterostilbene (PS)-loaded nanoparticles. Methods: Pterostilbene-hydroxypropyl ß-cyclodextrin inclusion complex loaded in chitosan nanoparticles (PS/HPßCD-NPs) were prepared and characterized in vitro. Cytotoxicity, pharmacokinetics and anti-obesity effects were assessed on Caco-2 cell line and high-fat-diet-induced obesity rat model, respectively. In vivo assessment included histological examination, protein and gene expression of obesity biomarkers in adipose tissues. Results: Safe PS/HPßCD-NPs were successfully prepared with improved bioavailability compared with free PS. PS/HPßCD-NPs showed an improved anti-obesity effect, as supported by histological examination, lipid profile, UCP1 gene expression and protein expression of SIRT1, COX2, IL-6 and leptin. Conclusion: Orally administered PS nanoparticles represent a new and promising anti-obesity strategy owing to the sustainable weight loss and minimal side effects; this may be of great socio-economic impact.

Weight gain or obesity represents a major health risk and leads to diseases including cancer and heart disease. Most anti-obesity medications have significant side effects, and there are notable challenges concerning their availability in the body to produce an effect. Pterostilbene is a herbal drug with beneficial anti-obesity effects. However, it has problems such as poor solubility which restrict its use. The aim of the study was to formulate pterostilbene in a nano-based delivery system and fully characterize its anti-obesity effect when given orally. We evaluated the safety and anti-obesity effects of pterostilbene nanoparticles in cells and in obese rats fed on a high-fat diet. We also looked at how the body absorbs, distributes and gets rid of these nanoparticles. The prepared nanoparticles were nontoxic, with an improved anti-obesity effect; they decreased cholesterol levels and helped in changing white fat (which stores fat) to brown fat (which burns calories). We conclude that the developed pterostilbene nanoparticles, given orally, are a new and promising anti-obesity strategy given their long-lasting effect on weight loss and the minimal side effects. This may be of great economic and societal impact.

Differential Immunometabolic Effects of High-Fat Diets Containing Coconut, Sunflower, and Extra Virgin Olive Oils in Female Mice.

SCOPE: To compare the effects of three high-fat diets (HFDs) based on coconut, sunflower, or extra virgin olive oils (EVOOs) on adipose tissue, metabolism, and inflammation. METHODS AND RESULTS: Mice are fed for 16 weeks on their respective HFD. HFD based on coconut oil produces significantly lower body weight than EVOO- or sunflower oil-based HFDs. Furthermore, the coconut oil HFD leads to metabolic disturbances such as reduction of circulating leptin and adiponectin concentrations, hypertriglyceridemia, hepatomegaly, and liver triglyceride accumulation. Likewise, this diet produces an increase in serum pro-inflammatory cytokines (interleukin 6 [IL-6] and tumor necrosis factor-α [TNF-α]). In white (WAT) and brown (BAT) adipose tissue, the HFD based on coconut oil does not cause significant changes in the expression of studied proteins related to thermogenesis (uncoupling protein 1 [UCP-1]), mitochondrial biogenesis, and browning (peroxisome proliferator-activated receptor-γ coactivator 1α [PGC-1α] and nuclear factor E2-related factor 2 [Nrf2]). However, the HFD based on EVOO induces upregulation of UCP-1, PGC-1α, and Nrf2 expression in BAT, increases the expression of UCP-1 and PGC-1α in inguinal WAT, and enhances the expression of PGC-1α in epididymal WAT. CONCLUSIONS: An HFD based on coconut oil could reduce circulating leptin and adiponectin concentrations, increase the liver fat content, raise serum triglycerides, and promote inflammation by increasing circulating pro-inflammatory cytokines, while an EVOO-based HFD could increase thermogenic activity.

Extract of Ephedra sinica Stapf Induces Browning of Mouse and Human White Adipocytes.

Browning of adipocytes using herbal extracts is an attractive and realistic strategy for obesity treatment. Ephedra sinica Stapf (E. sinica) is an Asian traditional medicine known to activate brown adipocytes. To evaluate the effect of E. sinica (EEs) on the browning of white adipocytes, expression levels of browning markers, including uncoupling protein 1 (UCP1), were determined using qPCR, Western blot, and immunocytochemistry after mature mouse inguinal preadipocyte (mIPA) and human adipose-derived stem cells (hADSCs) were treated with EEs. In addition, mitochondrial activity was determined by analyzing MitoTracker staining, mtDNA copy number, and oxygen consumption rate (OCR). Treatment with EEs suppressed lipid accumulation and expression levels of adipogenic markers, including Pparg, during mIPA differentiation. In mature mIPA and hADSCs browning markers, including Ucp1, were up-regulated by EEs. In addition, EEs increased expression of mitochondrial genes, mtDNA copy number, and OCR. EEs showed a dual function: inhibiting adipogenesis in immature preadipocytes, and promoting thermogenesis via browning in mature white adipocytes. Therefore, E. sinica is a potential herb for regulating energy metabolism by inducing the browning process.

Seed oil of Rosa roxburghii Tratt against non-alcoholic fatty liver disease in vivo and in vitro through PPARα/PGC-1α-mediated mitochondrial oxidative metabolism.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD), characterized by hepatic steatosis and hepatocyte injury, is an obesity-induced metabolic dysregulation with few available therapeutic options. Enhancement of the mitochondrial function was considered as an effective treatment for NALFD. Unsaturated fatty acids (UFAs) have been shown to have beneficial effects on metabolic syndrome disease such as hyperlipidemia, coronary artery disease and cardiovascular diseases. The seed oil of Rosa roxburghii Tratt (ORRT) was of high quality in terms of its high amount of unsaturated fatty acids. However, the effects of ORRT on NALFD have not been reported so far. PURPOSE: The study aimed to evaluate the protective effects and molecular mechanism of ORRT for the treatment of NAFLD in vivo and in vitro. METHODS: The beneficial effects, especially improving the mitochondrial function, and the potential mechanism of ORRT on NAFLD were studied both in vivo and in vitro. Lipid levels were determined by triglyceride (TG), total cholesterol (TC), and Oil Red O staining. Oxidative stress and inflammation were assessed by detecting antioxidant enzyme activity, MDA content, and ELISA assay. Blood TG, TC, HDL-c and LDL-c levels were measured in HFD mice. Western blot analyses were used to determine the levels of the protein involved in fatty acid oxidation, oxidative metabolism, and mitochondria biogenesis and function. The mitochondrial membrane potential level was measured by JC-1 staining to teste the effect of ORRT on mitochondrial function in vitro. GW6471 (inhibitor of PPARα) was used to confirm the relationship between PPARα and PGC-1α. RESULTS: ORRT significantly restrained NAFLD progression by attenuating lipid accumulation, oxidative stress and inflammatory response. Furthermore, ORRT upregulated thermogenesis-related gene expressions, such as uncoupling protein 1 (UCP1) and p38 mitogen-activated protein kinase (p38 MAPK). The results showed that the expression of key genes involved in fatty acid oxidation (e.g., CPT-1α, ACADL, PPARα) and in mitochondrial biogenesis and function (e.g., TFAM, NRF1, PGC-1α, and COX IV) was significantly increased. Together with the observed MMP improvement, these findings suggested that ORRT activated the mitochondrial oxidative pathway. Additionally, GW6471 inhibited the ORRT on promoting the expression of PGC-1α, CPT-1α, and ACADL. In conclusion, ORRT possessed the potential to prevent lipid accumulation via the PPARα/PGC-1α signaling pathway, which could be developed as a natural health-promoting oil against NAFLD.

Screening for anti-adipogenic, pro-lipolytic and thermogenic plant extracts by models associating intestinal epithelial cells with human adipose cells.

PURPOSE: Excessive fat mass accumulation in obesity leads to diverse metabolic disorders, increased risks of cardiovascular diseases and in some cases, mortality. The aim of this study was to screen the actions of botanical extracts intended for oral use on human adipose tissue, using an in vitro screening model combining human intestinal cells with human adipose cells. This was to find the most effective extracts on lipid accumulation, UCP1 expression and ATP production in pre-adipocytes and on adipocyte lipolysis. METHODS: In this study, 25 individual plant extracts were screened for their effects on human adipose cells. Consequently, an original in vitro model was set up using the Caco-2 cell line, to mimic the intestinal passage of the extracts and then exposing human adipose cells to them. The biological actions of extracts were thus characterized, and compared with a coffee extract standard. The most effective extracts, and their combinations, were retained for their actions on lipid accumulation, the expression of the thermogenic effector UCP1 and ATP production in pre-adipocytes as well as on lipolysis activity of mature adipocytes. RESULTS: The biphasic culture system combining human Caco-2 cells with human adipose cells was verified as functional using the green coffee extract standard. Out of the 25 plant extracts studied, only 7 and their combinations were retained due to their potent effects on adipose cells biology. The data showed that compared to the coffee extract standard, Immortelle, Catechu, Carrot and Rose hip extracts were the most effective in reducing lipid accumulation and increased UCP1 expression in human pre-adipocytes. CONCLUSION: This study reveals the potential inhibitory effects on lipid accumulation and thermogenic activity of Immortelle, Catechu, Carrot and Rose hip extracts, and for the first time synergies in their combinations, using an in vitro model mimicking as closely as possible, human intestinal passage linked to adipose cells. These findings need to be confirmed by in vivo trials.

Butein-Enriched Fractions of Butea monosperma (Lam.) Taub. Flower Decrease Weight Gains and Increase Energy Expenditure in High-Fat Diet-Induced Obese Mice.

Butea monosperma (Lam.) Taub. has been applied to treat inflammatory, metabolic, and infectious diseases. However, the antiobesity effects of B. monosperma (Lam.) Taub. flower (BMF) and the underlying mechanisms have not been determined. In this study, we analyzed the various extraction procedures, investigated the antiobesity effects, and identified the main chemical constituents of BMF. The BMF was subjected to acid hydrolysis in 5% H2SO4 in methanol at 50°C for 48 h and partitioned with ethyl acetate. The acid-hydrolyzed BMF ethyl acetate extracts (BMFE) strongly induced the expression of uncoupling protein 1 (Ucp1) and other thermogenic genes in C3H10T1/2 adipocytes. Daily oral administration of 70 mg/kg BMFE (BMFE70) to mice with diet-induced obesity resulted in less body weight gain, increased glucose tolerance, higher rectal temperature, and increased oxygen consumption. Qualitative and quantitative analyses along with treatments in Akt1 knockout mouse embryonic fibroblasts indicate that butein is a major active ingredient of BMFE, which stimulates Ucp1 gene expression. These data show the effects of butein-containing B. monosperma flower extract on thermogenesis and energy expenditure, further suggesting the potential role of BMFE as a functional ingredient in obesity and related metabolic diseases.

Effect of white tea consumption on serum leptin, TNF-α and UCP1 gene expression in ovariectomized rats.

BACKGROUND: Obesity and dyslipidemia due to estrogen deficiency are among the important health problems in menopausal women. Increasing evidence reports the anti-obesity and anti-hyperlipidemic properties of tea polyphenols. However, the effect of white tea (WT) with high polyphenol content on overweight and lipid profile is uncertain. Here, we aimed to examine the effects of long-term WT consumption on serum leptin, tumor necrosis factor- alpha (TNF-α) and uncoupling protein 1 (UCP1) mRNA gene expression in ovariectomized (OVX) rats. METHODS: Adult rats were divided into four groups (n = 8): (i) sham, (ii) OVX, (iii) WT and (iv) OVX + WT. WT was given at a dose of 0.5% w/v for 12 weeks. In the study, body weight, serum leptin, TNF, estradiol (E2) levels, lipid profile and UCP1 mRNA gene expression in brown adipose tissue (BAT) were evaluated. RESULTS: There was a significant increase in body weight of OVX rats, which was decreased following WT consumption. While leptin and E2 levels decreased in the OVX group, TNF levels increased. There was no difference between the NF-kB levels of the groups. In addition, BAT UCP1 mRNA expression was significantly decreased in OVX groups, while WT treatment stimulated UCP1 activity. CONCLUSION: We explain the stimulatory effect of WT on weight loss mainly by the induction of UCP1 gene-mediated thermogenesis and suppression of inflammation. Therefore, we suggest that prolonged WT consumption may have beneficial effects in limiting excess weight gain caused by estrogen deficiency.

Caloric Restriction and Hypothalamic Leptin Gene Therapy Have Differential Effects on Energy Partitioning in Adult Female Rats.

Dieting is a common but often ineffective long-term strategy for preventing weight gain. Similar to humans, adult rats exhibit progressive weight gain. The adipokine leptin regulates appetite and energy expenditure but hyperleptinemia is associated with leptin resistance. Here, we compared the effects of increasing leptin levels in the hypothalamus using gene therapy with conventional caloric restriction on weight gain, food consumption, serum leptin and adiponectin levels, white adipose tissue, marrow adipose tissue, and bone in nine-month-old female Sprague-Dawley rats. Rats (n = 16) were implanted with a cannula in the 3rd ventricle of the hypothalamus and injected with a recombinant adeno-associated virus, encoding the rat gene for leptin (rAAV-Lep), and maintained on standard rat chow for 18 weeks. A second group (n = 15) was calorically-restricted to match the weight of the rAAV-Lep group. Both approaches prevented weight gain, and no differences in bone were detected. However, calorically-restricted rats consumed 15% less food and had lower brown adipose tissue Ucp-1 mRNA expression than rAAV-Lep rats. Additionally, calorically-restricted rats had higher abdominal white adipose tissue mass, higher serum leptin and adiponectin levels, and higher marrow adiposity. Caloric restriction and hypothalamic leptin gene therapy, while equally effective in preventing weight gain, differ in their effects on energy intake, energy expenditure, adipokine levels, and body composition.

Leptin Modulates the Response of Brown Adipose Tissue to Negative Energy Balance: Implication of the GH/IGF-I Axis.

The growth hormone (GH)/insulin-like growth factor I (IGF-I) axis is involved in metabolic control. Malnutrition reduces IGF-I and modifies the thermogenic capacity of brown adipose tissue (BAT). Leptin has effects on the GH/IGF-I axis and the function of BAT, but its interaction with IGF-I and the mechanisms involved in the regulation of thermogenesis remains unknown. We studied the GH/IGF-I axis and activation of IGF-I-related signaling and metabolism related to BAT thermogenesis in chronic central leptin infused (L), pair-fed (PF), and control rats. Hypothalamic somatostatin mRNA levels were increased in PF and decreased in L, while pituitary GH mRNA was reduced in PF. Serum GH and IGF-I concentrations were decreased only in PF. In BAT, the association between suppressor of cytokine signaling 3 and the IGF-I receptor was reduced, and phosphorylation of the IGF-I receptor increased in the L group. Phosphorylation of Akt and cyclic AMP response element binding protein and glucose transporter 4 mRNA levels were increased in L and mRNA levels of uncoupling protein-1 (UCP-1) and enzymes involved in lipid anabolism reduced in PF. These results suggest that modifications in UCP-1 in BAT and changes in the GH/IGF-I axis induced by negative energy balance are dependent upon leptin levels.

IRX3 Overexpression Enhances Ucp1 Expression In Vivo.

Objective: The Iroquois homeobox 3 (IRX3) gene was recently reported to be a functional downstream target of a common polymorphism in the FTO gene, which encodes an obesity-associated protein; however, the role of IRX3 in energy expenditure remains unclear. Studies have revealed that the overexpression of a dominant-negative form of IRX3 in the mouse hypothalamus and adipose tissue promoted energy expenditure by enhancing brown/browning activities. Meanwhile, we and others recently demonstrated that IRX3 knockdown impaired the browning program of primary preadipocytes in vitro. In this study, we aimed to further clarify the effects of overexpressing human IRX3 (hIRX3) on brown/beige adipose tissues in vivo. Methods: Brown/beige adipocyte-specific hIRX3-overexpressing mice were generated and the browning program of white adipose tissues was induced by both chronic cold stimulation and CL316,243 injection. Body weight, fat mass, lean mass, and energy expenditure were measured, while morphological changes and the expression of thermogenesis-related genes in adipose tissue were analyzed. Moreover, the browning capacity of primary preadipocytes derived from hIRX3-overexpressing mice was assessed. RNA sequencing was also employed to investigate the effect of hIRX3 on the expression of thermogenesis-related genes. Results: hIRX3 overexpression in embryonic brown/beige adipose tissues (Rosa26hIRX3 ;Ucp1-Cre) led to increased energy expenditure, decreased fat mass, and a lean body phenotype. After acute cold exposure or CL316,243 stimulation, brown/beige tissue hIRX3-overexpressing mice showed an increase in Ucp1 expression. Consistent with this, induced hIRX3 overexpression in adult mice (Rosa26hIRX3 ;Ucp1-CreERT2) also promoted a moderate increase in Ucp1 expression. Ex vitro experiments further revealed that hIRX3 overexpression induced by Ucp1-driven Cre recombinase activity upregulated brown/beige adipocytes Ucp1 expression and oxygen consumption rate (OCR). RNA sequencing analyses indicated that hIRX3 overexpression in brown adipocytes enhanced brown fat cell differentiation, glycolysis, and gluconeogenesis. Conclusion: Consistent with the in vitro findings, brown/beige adipocyte-specific overexpression of hIRX3 promoted Ucp1 expression and thermogenesis, while reducing fat mass.

The phytochemical hyperforin triggers thermogenesis in adipose tissue via a Dlat-AMPK signaling axis to curb obesity.

Stimulation of adipose tissue thermogenesis is regarded as a promising avenue in the treatment of obesity. However, pharmacologic engagement of this process has proven difficult. Using the Connectivity Map (CMap) approach, we identified the phytochemical hyperforin (HPF) as an anti-obesity agent. We found that HPF efficiently promoted thermogenesis by stimulating AMPK and PGC-1α via a Ucp1-dependent pathway. Using LiP-SMap (limited proteolysis-mass spectrometry) combined with a microscale thermophoresis assay and molecular docking analysis, we confirmed dihydrolipoamide S-acetyltransferase (Dlat) as a direct molecular target of HPF. Ablation of Dlat significantly attenuated HPF-mediated adipose tissue browning both in vitro and in vivo. Furthermore, genome-wide association study analysis indicated that a variation in DLAT is significantly associated with obesity in humans. These findings suggest that HPF is a promising lead compound in the pursuit of a pharmacological approach to promote energy expenditure in the treatment of obesity.

Nutmeg extract potentially alters characteristics of white adipose tissue in rats.

BACKGROUND: Browning of white adipose tissue (WAT) is a promising approach to obesity treatment. During browning, WAT transforms into beige adipose tissue through stimulation of the peroxisome proliferator activated receptor γ (PPARγ). Nutmeg, one of the Indonesian herbs, reportedly has dual roles as a PPARα/γ partial agonist. Even though nutmeg has been traditionally used in body weight reduction, there is limited information regarding the potential role of nutmeg in browning of WAT. OBJECTIVES: In this study, we explored the effect of nutmeg seed extract (NuSE) as a potential inductor of WAT browning. METHODS: Twelve male Wistar rats, 5-6 weeks old, were divided into control and nutmeg groups. The rats in nutmeg group were given NuSE for 12 weeks by oral gavage. After 12 weeks, the rat's inguinal WAT and brown adipose tissue (BAT) were collected, weighed and stored at - 80°C until use. RESULTS: We observed that even though NuSE did not reduce the final body weight, it significantly reduced body weight gain. NuSE also increased protein levels of peroxisome proliferator activated receptor γ coactivator 1α (PGC-1α) and uncoupling protein 3 (UCP3) significantly and tended to increase UCP2 and UCP1 levels. Furthermore, NuSE induced macroscopic and microscopic morphological changes of inguinal WAT, marked by significantly increased adipocyte numbers and decreased adipocyte size. CONCLUSIONS: Even though NuSE did not increase UCP1 significantly, it potentially alters inguinal WAT characteristics and leads to browning through PGC-1α and UCP3 induction. However, UCP3's specific mechanism in WAT browning remains unclear. Our findings could contribute to obesity treatment in the future.