Brown Adipose Tissue Activity Research Articles

Secretin infusion decreases food intake in healthy men – a randomized, placebo-controlled, double-blind, crossover study

Abstract Design The hormone secretin, best known for regulating pH in the duodenum, has anorectic properties in mice proposedly mediated via secretin-induced brown adipose tissue (BAT) activation. We investigated the effects of exogenous secretin on ad libitum food intake, BAT activity, and postprandial physiology in healthy male volunteers. Methods In a randomized, placebo-controlled, double-blind, crossover study, 25 healthy men underwent two 5-hour i.v. infusions of secretin (1 pmol/kg/min) and placebo (saline), respectively, with an interposed two-month wash-out period. After 30 min of infusion, a standardized liquid mixed meal was ingested and after 5 hours, food intake and meal duration were assessed during an ad libitum meal test. BAT activity was assessed regularly by thermal imaging-measured supraclavicular skin temperature. Results Compared to placebo, secretin significantly decreased ad libitum food intake by 173 ± 88 kcal [95% CI 0.76 to 0.99, P = 0.039], but did not alter ad libitum meal duration. Secretin acutely decreased BAT activity but increased it postprandially compared to placebo. Acetaminophen-assessed gastric emptying was not affected by exogenous secretin, but secretin increased gallbladder volume, bile acid synthesis, and circulating levels of lipase, amylase and triglycerides, while decreasing plasma Na+. Compared to placebo, secretin infusion was associated with 24.0 ± 10.8% (95% CI 0.3 to 1, P = 0.025) more adverse events (headache, nausea, diarrhoea, and vomiting). Conclusions In healthy men, secretin infusion decreased ad libitum food intake concomitantly with a postprandial increase in BAT activity as assessed by thermal imaging-measured supraclavicular skin temperature. Trial registration Clinicaltrials.gov, NCT04613700

Abstract 4140191: ChREBP Drives Brown Adipocyte Differentiation and Lipid Utilization for Excess Energy Expenditure

Introduction: Although several anti-obesity drugs have become recently available, they reduce patients’ appetite, which might worsen cardiovascular disease (CVD) prognosis by malnutrition/cachexia. Brown adipose tissue (BAT) oxidizes glucose and lipids for thermogenesis, a process that requires excess energy expenditure provided by uncoupling protein 1 (UCP1) + cells. Recently, critical roles of BAT in cardio-protection have been discovered. Taken together, boosting BAT activity can be a novel anti-obesity treatment suitable for CVD patients. In this study, we aimed to establish anti-obesity strategy by manipulation of the glucose-sensing lipid-storage transcription factor, ChREBP, with unexpected function of boosting lipid utilization in BAT. Methods and Results: Through mouse/human single-cell/nucleus RNA sequencing analyses, we identified ChREBP as specifically expressed in highly thermogenic UCP1 + brown adipocytes ( Fig.A ). To investigate the role of ChREBP in BAT formation, we generated human brown adipocyte-like model from induced pluripotent stem cells (iPSC-BAT, Fig.B ). The iPSC-BAT exhibited high UCP1 and ChREBP expression, multi-locular lipid droplets, and vigorous oxygen consumption. Knocking down ChREBP strongly blocked iPSC-BAT differentiation ( Fig.C ) and impaired lipid utilization ( Fig.D ). Consistently, in vitro deletion of ChREBP in mouse BAT progenitors impeded differentiation, lipid droplet accumulation, and oxygen consumption ( Fig.E-F ). In vivo, BAT-specific deletion of all ChREBP isoforms reduced lipid accumulation and BAT characteristics. Conversely, using a new mouse model for Cre-mediated ChREBPβ overexpression, we showed that ChREBPβ overexpression in BAT (Chβ BATOX) increased BAT cellularity and activated lipogenic machineries, with paradoxical decreased lipid content, suggesting excessively activated lipid consumption in BAT ( Fig.G ). More importantly, Chβ BATOX maintained UCP1 expression and reduced fat volume ( Fig.H ) even after strongly inhibiting BAT activity. Conclusion: In summary, ChREBP is essential for BAT development and thermogenic capacity by affecting lipid utilization. Our results suggest that ChREBPβ activation may be a novel anti-obesity avenue for CVD patients.

Dietary Lactate Intake and Physical Exercise Synergistically Reverse Brown Adipose Tissue Whitening to Ameliorate Diet-Induced Obesity.

Physical exercise represents an effective strategy for combating obesity via brown adipose tissue (BAT) activation, but the mechanism remains unclear. In this study, we demonstrated that the cooperation between lactate and adrenoceptor signaling regulated BAT activity during exercise. The lactate receptor GPR81 was highly expressed in the BAT of lean mice, whereas its expression was markedly decreased in obese mice. Notably, the level of GPR81 in BAT could be upregulated by exercise. The blockade of lactate production or GPR81 significantly impaired exercise-induced BAT activation. In addition, dietary lactate intake enhanced the efficacy of physical exercise in alleviating BAT whitening in obese mice, as evidenced by the improved mitochondrial ultrastructure, reduced lipid droplets, increased UCP1 expression, and elevated mitochondrial DNA content. Further data indicated that norepinephrine triggered UCP1 activation through both the cAMP/PKA and Ca2+/CaMK pathways during exercise, while lactate mediated this process via the GPR81-Ca2+/CaMK cascade. Our findings unveil a novel mechanism in the regulation of BAT function by physical exercise, providing a promising lifestyle intervention to improve metabolic health.

The role of active brown adipose tissue in patients with pheochromocytoma or paraganglioma (PPGL)

The role of active brown adipose tissue in patients with pheochromocytoma or paraganglioma (PPGL)

Dietary Intake Is Similar Among Adult Men with Different Levels of Cold-Induced Brown Adipose Tissue Activation.

Brown adipose tissue (BAT) activation has important metabolic health implications, yet the relationship between habitual dietary intake and BAT activity in humans remains to be fully understood. We compared dietary intake among adult men with (BATpositive, age: 34.8 ± 5.4 years, BMI: 28.2 ± 5.3 kg/m2, n = 12) and without (BATnegative, age: 39.1 ± 4.1 years, BMI: 31.1 ± 6.7 kg/m2, n = 11) cold-induced BAT activation. Activation of BAT was measured immediately following 2 h of cold exposure using 18F fluorodeoxyglucose positron emission tomography and computed tomography reported as maximum standardized uptake (SUVmax). Participants categorized as BATpositive had an SUVmax > 1.5 g/mL that was normalized to lean body mass (SUVlean) for analysis. Shivering intensity was recorded every 15 min during cold exposure and dietary intake was estimated from 7 consecutive 24 h dietary recalls. The BATnegative group was significantly older than the BATpositive group (p = 0.046). Although BATnegative participants consumed an average of 281.2 kcal/day more than BATpositive, there were no significant differences in dietary intake between groups (p ≥ 0.202). Further, no statistically significant associations between SUVlean and dietary intake among BATpositive participants were observed (p ≥ 0.175). Participants who shivered (n = 9) during cold exposure tended to be shorter (p = 0.056) and have a lower waist-to-hip ratio (p = 0.097) but did not differ in dietary intake (p ≥ 0.204) or BAT activity (p = 0.964) when compared to the non-shivering (n = 11) group. Our results indicate that BAT activity and shivering during cold exposure are more strongly related to variables such as age and body size or composition rather than habitual dietary intake. We conclude that habitual dietary intake likely has a negligible influence on BAT activity among adult men.

Preliminary study on the effects of boysenberry juice intake on brown adipose tissue activity in healthy adults

Brown adipose tissue (BAT) plays an important role in energy metabolism because it uses fatty acids for thermogenesis during cold exposure. Preclinical studies found that boysenberry anthocyanins (BoyACs) activate BAT. Therefore, the aim of this preliminary study was to evaluate how BoyAC intake affects BAT in humans. We performed an open-label single-arm nonrandomized study in healthy volunteers. Before and after 4 weeks of daily consumption of 100 ml boysenberry juice (BoyJ) containing 61 mg of BoyACs, participants were assessed at 24 °C and then after 1 h of mild cold exposure (18 °C). An infrared thermography camera was used to measure skin surface temperatures in the supraclavicular BAT region (Tscv) and the non-BAT region of the upper chest (Tch). Energy metabolism was measured by indirect calorimetry. For each endpoint, we calculated Δ as the difference between values before and after cold exposure and compared the values before and after BoyJ intake. 10 volunteers participated (age: 36.1 ± 4.1, body mass index (BMI): 20.9 ± 0.6). After BoyJ intake, ΔTscv-ch was significantly higher (p = 0.029), but Δ energy expenditure, Δ fat oxidation, and Δ carbohydrate oxidation were not significantly different. We found a significant positive correlation between BMI and Δfat oxidation with BoyJ intake. The results indicate that 4 weeks of BoyJ intake activates cold-induced thermogenesis in the scv-BAT but does not have a significant effect on energy metabolism. BoyJ intake may increase fat oxidation during cold exposure in individuals with higher BMI.Trial registry number: UMIN000043476, 05/03/2021.

Brown adipose tissue activation in paediatric and adolescent oncological (Hodgkin lymphoma or sarcoma) cases visualised on FDG PET/CT

Brown adipose tissue activation in paediatric and adolescent oncological (Hodgkin lymphoma or sarcoma) cases visualised on FDG PET/CT

Sympathetic Innervation of Interscapular Brown Adipose Tissue Is Not a Predominant Mediator of Oxytocin-Induced Brown Adipose Tissue Thermogenesis in Female High Fat Diet-Fed Rats.

Recent studies have indicated that hindbrain [fourth ventricle (4V)] administration of the neurohypophyseal hormone, oxytocin (OT), reduces body weight, energy intake and stimulates interscapular brown adipose tissue temperature (TIBAT) in male diet-induced obese (DIO) rats. What remains unclear is whether chronic hindbrain (4V) OT can impact body weight in female high fat diet-fed (HFD) rodents and whether this involves activation of brown adipose tissue (BAT). We hypothesized that OT-elicited stimulation of sympathetic nervous system (SNS) activation of interscapular brown adipose tissue (IBAT) contributes to its ability to activate BAT and reduce body weight in female high HFD-fed rats. To test this hypothesis, we determined the effect of disrupting SNS activation of IBAT on OT-elicited stimulation of TIBAT and reduction of body weight in DIO rats. We first measured the impact of bilateral surgical SNS denervation to IBAT on the ability of acute 4V OT (0.5, 1, and 5 µg ≈ 0.5, 0.99, and 4.96 nmol) to stimulate TIBAT in female HFD-fed rats. We found that the high dose of 4V OT (5 µg ≈ 4.96 nmol) stimulated TIBAT similarly between sham rats and denervated rats (p = NS). We subsequently measured the effect of bilateral surgical denervation of IBAT on the effect of chronic 4V OT (16 nmol/day ≈ 16.1 μg/day) or vehicle infusion to reduce body weight, adiposity and energy intake in female HFD-fed rats (N = 7-8/group). Chronic 4V OT reduced body weight gain (sham: -18.0 ± 4.9 g; denervation: -15.9 ± 3.7 g) and adiposity (sham: -13.9 ± 3.7 g; denervation: -13.6 ± 2.4 g) relative to vehicle treatment (p < 0.05) and these effects were similar between groups (p = NS). These effects were attributed, in part, to reduced energy intake evident during weeks 2 (p < 0.05) and 3 (p < 0.05). To test whether these results translate to other female rodent species, we also examined the effect of chronic 4V infusion of OT on body weight and adiposity in two strains of female HFD-fed mice. Similar to what we found in the HFD-fed rat model, we also found that chronic 4V OT (16 nmol/day) infusion resulted in reduced body weight gain, adiposity and energy intake in female DIO C57BL/6J and DBA/2J mice (p < 0.05 vs. vehicle). Together, these findings suggest that (1) sympathetic innervation of IBAT is not necessary for OT-elicited increases in BAT thermogenesis and weight loss in female HFD-fed rats and (2) the effects of OT to reduce weight gain and adiposity translate to other female mouse models of diet-induced obesity (DIO).

Bimagrumab: an investigational human monoclonal antibody against activin type II receptors for treating obesity.

Bimagrumab is a human monoclonal antibody that prevents activin type II receptors (ActRII) from functioning. This antibody has a higher affinity for muscle activin-2 receptors than natural ligands such as activin and myostatin, which act as negative muscle growth regulators. Blocking the activin receptor with bimagrumab could be a new pharmaceutical approach for managing patients with obesity and type 2 diabetes mellitus (T2DM). Bimagrumab has anabolic effects on skeletal muscle mass by preventing myostatin binding and other negative muscle growth regulators. Preclinical animal models have also shown that ActRII blockade promotes actions beyond skeletal muscle, including effects on brown adipose tissue (BAT) differentiation and activity. In a phase 2 randomized clinical trial, ActRII blockade with bimagrumab led to significant loss of total body fat mass (FM), lean mass (LM) gain, and metabolic improvements over 48weeks in overweight or obese patients with type 2 diabetes. The trial involved [number of participants], and the results showed [specific findings]. Currently, Bimagrumab is being evaluated for its potential to treat muscle wasting, functional loss in hip fractures and sarcopenia, as well as obesity. However, it is essential to note that Bimagrumab also blocks the effects of other ActRII ligands, which play a role in the neurohormonal axes, pituitary, gonads, and adrenal glands. These observations suggest that bimagrumab might represent a new approach for treating patients with obesity and related metabolic disturbances.

FDG Uptake in Brown Adipose Tissue Activated by a Long-Acting β2-Adrenergic Receptor Agonist Inhaler Prescribed for Bronchial Asthma.

We herein report a case of an elderly woman in whom brown adipose tissue (BAT) was visible on 18 F-FDG PET imaging performed in the summer. In this patient, none of the well-known factors that induce BAT activation in adults, including cold exposure, catecholamine-producing tumors, or β3-adrenergic receptor agonists administration, were present. Daily inhalation of a long-acting β2-adrenergic agonist for treatment of her bronchial asthma was considered the cause of her BAT visualization. This case suggests the need to consider β2-adrenergic receptor agonists as a cause of BAT visualization.

Brown adipose tissue: a potential target for aging interventions and healthy longevity.

Brown Adipose Tissue (BAT) is a type of fat tissue that can generate heat and plays an important role in regulating body temperature and energy metabolism. Enhancing BAT activity through medication, exercise and other means has become a potential effective method for treating metabolic disorders. Recently, there has been increasing evidence suggesting a link between BAT and aging. As humans age, the volume and activity of BAT decrease, which may contribute to the development of age-related diseases. Multiple organelles signaling pathways have been reported to be involved in the aging process associated with BAT. Therefore, we aimed to review the evidence related to the association between aging process and BAT decreasing, analyze the potential of BAT as a predictive marker for age-related diseases, and explore potential therapeutic strategies targeting BAT for aging interventions and healthy longevity.

8515 Role of Insulin Receptor in Trpv1-positive Adipocyte Progenitor Cellsin Adipocyte Differentiation and Metabolic Function

Abstract Disclosure: C. Sahin: None. H. Camara: None. F. Shamsi: None. M. Lynes: None. Y. Tseng: None. Brown adipose tissue (BAT), a specialized fat that dissipates energy to produce heat, is an important endocrine organ in the regulation of energy balance. Stimulating BAT activation and beiging of white adipose tissue (WAT) are new strategies to combat metabolic diseases, such as obesity and diabetes. Traditionally, thermogenic adipocytes are known to originate from mesenchymal Pdgfrα-expressing adipocyte progenitor cells (APCs). A previous study conducted by our lab identified vascular smooth muscle cells as a novel cellular origin of APCs. These cells are characterized by the expression of transient receptor potential cation channel subfamily V member 1 (Trpv1+). With cold exposure, the Trpv1+ APC-derived adipocytes are increased in BAT and WAT and differentiated into highly thermogenic adipocytes. These findings indicate that the Trpv1+-APCs may play an important role in the development of brown and beige adipocytes in response to cold. This study was designed to explore the function of the Trpv1+ APC-derived adipocytes in thermogenic adipocyte differentiation and metabolic regulation. We generated a mouse model in which insulin receptor (IR), a well-known player in adipocyte differentiation, was deleted in the Trpv1+ APCs to impair their adipogenic potential. Trpv1-Cre::mTmG::IRflox transgenic and IRwt control mice were housed at cold temperature (5°C) for 7 days. Because the lineage tracing mTmG system was included, we were able to trace the fate of Trpv1+ APCs in the presence or absence of IR. We first examined the adipogenic capacity of the IR-deficient Trpv1+ cells in BAT and WAT tissues using whole-mounted adipose tissue imaging. In control mice, approximately 30% of all mature adipocytes were derived from Trpv1+ APCs in adipose tissue in response to cold. With ablation of IR in Trpv1+ APCs, this contribution was significantly reduced in BAT (by 11.7 % in females; 6.1% in males), inguinal WAT (by 16.8% in females; 19.3% males), and perigonadal WAT (by 11.4% in females; 14.8% in males) in transgenic mice compared to control mice. These results showed that IR-deficiency in the Trpv1-expressing cells impaired their adipogenesis in both male and female mice. In contrast, thermogenic genes (e.g., Ucp1, Pparγc1a, Cox7a1) were not significantly altered in BAT and inguinal WAT of the IR-deficient Trpv1+ APCs mice. Despite the changes in the adipocyte populations, we observed that deletion of IR in Trpv1+ APCs has no impact on body weight, food intake, fat mass, glucose tolerance, and insulin sensitivity relative to control mice. Taken together, blocking the contribution of Trpv1+ APCs to the mature adipocyte population results in no metabolic changes in mice, suggesting that the other APCs, such as PdgfRα+ APCs, may potentially compensate for impaired adipogenesis in different adipose tissues. Presentation: 6/1/2024

8159 Single Nuclei RNA-Sequencing Reveals Novel Cellular Diversity in Human Neck Adipose Tissue

Abstract Disclosure: H. Camara: None. S.D. Kodani: Employee; Self; Hoxton Farm. S. Yang: None. V. Efthymiou: None. K. An: None. A. Gupta: None. F. Shamsi: None. A. Streets: None. M.E. Patti: Advisory Board Member; Self; Fractyl Laboratories. Consulting Fee; Self; AstraZeneca, Hamni, MBX Biosciences. Grant Recipient; Self; Dexcom. Y. Tseng: Consulting Fee; Self; LyGenesis. Other; Self; BioHaven. Adipose tissue plays a crucial role in maintaining metabolic health. It fulfills distinct functions through two types of fat: white adipose tissue (WAT), the primary site of triglyceride storage, and brown adipose tissue (BAT) along with related beige fat, specializing in thermogenic energy expenditure. Despite the scarcity of BAT in humans, these thermogenic adipocytes efficiently utilize glucose and triglycerides and act as an endocrine organ by secreting batokines. Hence, increased BAT activity is associated with improved metabolic health in humans. In adults, thermogenic adipose tissue is localized in deep neck planes, exhibiting a gradient from white to beige/brown from superficial to deep layers. Mounting evidence suggests the diverse cell types within the adipose tissue and their dynamic interactions play an important role in its versatile functions. To understand the cellular compositions of human adipose tissue and directly compare the differences between human BAT vs. WAT, we collected 30 paired samples of superficial, intermediate and deep human neck adipose tissue from 15 participants who underwent anterior cervical discectomy fusion or thyroid surgery and subjected the frozen tissues to single-nucleus RNA sequencing (snRNA-seq). The integration of the samples yielded 41,337 good-quality nuclei. As expected, white adipocytes (WAd) were the dominant cell type, comprising 38% of the total cells captured. Further analysis of the WAd cluster revealed increased expression of brown adipocyte-associated genes, such as EBF2 and COBL, and enrichment of oxidative phosphorylation pathway score in cells from deep neck samples, indicating increased thermogenic potential. Bona fide brown adipocytes (BAds), marked by the expression of PPARGC1A, were predominantly located in the deep neck samples (&amp;gt;80%) but comprised less than 2% of the dataset. Despite their low numbers, cell-cell communication analysis by CellChat predicted that BAds account for most of the communication events within this niche, highlighting their endocrine importance. snRNA-seq also captured non-adipocyte cells, including adipocyte progenitors, smooth muscle, immune, Schwann and neuron-associated cells. Among these, a novel Neuron-Associated Cell-1, marked by the expression of CNTNAP2, emerged as the second most abundant in the dataset (∼10% of total). Another neuron-associated cell population marked by expression of DNAH11, though less abundant (∼1%), was enriched in deep neck samples, potentially regulating the high levels of thermogenic potential in this region. Taken together, the identified subpopulations and their gene expression profiles offer new insights into the tissue's role in metabolic regulation. This knowledge could be pivotal for developing targeted therapies for obesity and related disorders. Presentation: 6/1/2024

Association of brown adipose tissue activity with circulating sex hormones and fibroblast growth factor 21 in the follicular and luteal phases in young women

BackgroundThermogenesis is influenced by fluctuations in sex hormones during the menstrual cycle in premenopausal women. The thermogenic activity and mass of brown adipose tissue (BAT) are regulated by endocrine factors, including sex hormones and fibroblast growth factor 21 (FGF21). However, the relationship between human BAT and these endocrine fluctuations within individuals remains to be elucidated. This study aimed to assess variations in BAT activity between the luteal and follicular phases and identify correlations with circulating levels of sex hormones and FGF21.MethodsHealthy young women were enrolled in an observational study. Measurement of BAT activity and blood analyses were performed in both the follicular and luteal phases. BAT activity was analyzed using thermography with 2-h cold exposure. Plasma 17β-estradiol, progesterone, and FGF21 levels were determined by enzyme-linked immunosorbent assay. A comparative analysis within individuals was conducted in 13 women to compare the follicular and luteal phases. Furthermore, sensitivity analysis was carried out in 21 women during the follicular phase only.ResultsPlasma 17β-estradiol and progesterone levels were significantly higher in the luteal phase, whereas plasma FGF21 level was significantly higher in the follicular phase. Comparison analysis found no significant differences in cold-induced BAT activity between the follicular and luteal phases in young women. Correlation analysis in both comparison and sensitivity analyses found that plasma 17β-estradiol and progesterone levels were not associated with BAT activity, whereas plasma FGF21 levels were significantly and positively correlated with BAT activity only in the follicular phase. In addition, plasma 17β-estradiol levels in the follicular phase were significantly and positively associated with plasma FGF21 levels in both the comparison and sensitivity analyses.ConclusionsThe thermogenic activity of BAT during cold exposure was comparable between the follicular and luteal phases in young women. Higher BAT activity was associated with elevated levels of plasma FGF21 only in the follicular phase, which is related to increased plasma 17β-estradiol levels.

Effects of macronutrients on brown adipose tissue activity: A comparative study using non-invasive imaging techniques in healthy adults

Effects of macronutrients on brown adipose tissue activity: A comparative study using non-invasive imaging techniques in healthy adults

Predicting standardized uptake value of brown adipose tissue from CT scans using convolutional neural networks.

The standard method for identifying active Brown Adipose Tissue (BAT) is [18F]-Fluorodeoxyglucose ([18F]-FDG) PET/CT imaging, which is costly and exposes patients to radiation, making it impractical for population studies. These issues can be addressed with computational methods that predict [18F]-FDG uptake by BAT from CT; earlier population studies pave the way for developing such methods by showing some correlation between the Hounsfield Unit (HU) of BAT in CT and the corresponding [18F]-FDG uptake in PET. In this study, we propose training convolutional neural networks (CNNs) to predict [18F]-FDG uptake by BAT from unenhanced CT scans in the restricted regions that are likely to contain BAT. Using the Attention U-Net architecture, we perform experiments on datasets from four different cohorts, the largest study to date. We segment BAT regions using predicted [18F]-FDG uptake values, achieving 23% to 40% better accuracy than conventional CT thresholding. Additionally, BAT volumes computed from the segmentations distinguish the subjects with and without active BAT with an AUC of 0.8, compared to 0.6 for CT thresholding. These findings suggest CNNs can facilitate large-scale imaging studies more efficiently and cost-effectively using only CT.

Differential mitochondrial adaptation and FNDC5 production in brown and white adipose tissue in response to cold and obesity.

Fibronectin type III domain-containing protein 5 (FNDC5) modulates adipocyte metabolism by increasing white and brown adipose tissue (WAT and BAT) browning and activity, respectively. We investigated whether FNDC5 can regulate visceral WAT and BAT adaptive thermogenesis by improving mitochondrial homeostasis in response to cold and obesity. Adipose tissue expression of FNDC5 and factors involved in mitochondrial homeostasis were determined in patients with normal weight and obesity (n = 159) and in rats with diet-induced obesity after 1 week of cold exposure (n = 61). The effect of different FNDC5 concentrations on mitochondrial biogenesis, dynamics, and mitophagy was evaluated in vitro in human adipocytes. In human visceral adipocytes, FNDC5/irisin triggered mitochondrial biogenesis (TFAM) and fusion (MFN1, MFN2, and OPA1) while inhibiting peripheral fission (DNM1L and FIS1) and mitophagy (PINK1 and PRKN). Circulating and visceral WAT expression of FNDC5 wasdecreased in patients and experimental animals with obesity, whereas its receptor, integrin αV, was upregulated. Obesity increased mitochondrial fusion while decreasing mitophagy in visceral WAT from patients and rats. By contrast, in rat BAT, an upregulation of Fndc5 and genes involved in mitochondrial biogenesis and fission was observed. Cold exposure promoted mitochondrial biogenesis and healthy peripheral fission while repressing Fndc5 expression and mitophagy in BAT from rats. Depot differences in FNDC5 production and mitochondrial adaptations in response to obesity and cold might indicate a self-regulatory mechanism to control thermogenesis in response to energy needs.

Fatty acids promote uncoupled respiration via the ATP/ADP carrier in white adipocytes.

Adipocytes store energy as triglycerides, while mobilizing energy when needed via lipolysis. Triglyceride lipolysis releases fatty acids and glycerol into the circulation to fuel other tissues. However, a significant fraction of fatty acids released by lipolysis are retained within the white adipose tissue and handled by adipocytes. While some of these retained fatty acids are re-esterified in white adipocytes 1-6 , the a substantial amount undergo oxidative metabolism via a pathway regulated by the nongenomic effects of STAT3 7-10 . Here we report that fatty acids promote uncoupled oxidative metabolism in white adipocytes via the ATP/ADP carrier, contributing to thermogenesis and cold tolerance in obese thermoneutral-adapted mice, independent of brown adipose tissue and muscle activity. Our results suggest that uncoupled respiration in white adipocytes significantly contributes to whole-body energy expenditure and could be a promising target for obesity treatment.

The Therapeutic Potential of Theobromine in Obesity: A Comprehensive Review.

Obesity, characterized by chronic low-grade inflammation, is a significant health concern. Phytochemicals found in plants are being explored for therapeutic use, particularly in combating obesity. Among these, theobromine, commonly found in cocoa and chocolate, shows promise. Although not as extensively studied as caffeine, theobromine exhibits positive effects on human health. It improves lipid profiles, aids in asthma treatment, lowers blood pressure, regulates gut microbiota, reduces tumor formation, moderates blood glucose levels, and acts as a neuroprotective agent. Studies demonstrate its anti-obesity effects through mechanisms such as browning of white adipose tissue, activation of brown adipose tissue, anti-inflammatory properties, and reduction of oxidative stress. This study aims to suggest theobromine as a potential therapeutic agent against obesity-related complications.

Effects of NET-2201 (Capsicum chinense L. cv.) on brown adipose tissue activation and white adipose tissue browning in high-fat-diet-induced obese mice

Effects of NET-2201 (Capsicum chinense L. cv.) on brown adipose tissue activation and white adipose tissue browning in high-fat-diet-induced obese mice