Target For Treatment Of Obesity Research Articles

Orexin-A and endocannabinoid signaling regulate glucose-responsive arcuate nucleus neurons and feeding behavior in obese rats

Obesity is a global public health problem. Orexin and endocannabinoid signaling in the hypothalamus have been shown to regulate feeding and are promising molecular targets for obesity treatment. In this study, we attempted to analyze effects of orexin-A and endocannabinoid signaling modulation in the arcuate nucleus (Arc) on feeding and glucose-responsive (GR) neurons physiology in a diet-induced obesity (DIO) and diet-induced obesity resistant (DR) rat model. Administration of orexin-A or cannabinoid receptor type-1 (CB1R) antagonist AM251 altered the firing of GR neurons in the Arc. The effects of orexin-A were eliminated by pre-administrating orexin-1 receptor (OX-1R) antagonist SB334867, respectively. Behavioral studies showed that orexin-A increased food intake, while AM251 reduced feeding. Histological studies showed that mRNA and protein expression of OX-1R (orexin-1 receptor) and CB1R were increased in the Arc of DIO and DR rats. Our results strongly suggest that orexin-A and endocannabinoid signaling in Arc plays an important role in regulating GR neuronal excitability and food intake in obesity.

Indomethacin Induces Browning and Brown Adipogenesis in Murine 3T3‐L1 White Adipocytes and Human Brown Fat Cells

Functional brown adipose tissue, including classical brown adipocytes and brown‐like or beige adipocytes, which develop within white adipose tissue in response to various stimuli, have emerged as novel targets for obesity treatment and prevention. Identifying strategies that increase UCP‐1 expression and induce browning and brown adipogenesis is key to unlocking thermogenic potential. Indomethacin (INDO) is a non‐selective Cox‐1/Cox‐2 inhibitor which is an approved NSAID used to treat and relief inflammatory diseases. It has been reported that INDO induced C3H10T1/2 mesenchymal stem cell differentiation into adipocytes by activating PPARg, which is also important for browning and brown adipogenesis. In this study, INDO was tested at various doses (2, 5, 10, 20, 50 mM) in 3T3‐L1 mouse pre‐adipocytes in a 7‐day differentiation process as well as human brown fat cells in a 21‐day differentiation process. Rosiglitazone (ROSI), a well‐known browning agent and PPARg agonist, was used as a positive control. At the end of differentiation, 3T3‐L1 cells were subjected to thermogenic activation by isoproterenol (ISO), a b‐adrenergic receptor agonist, or the control for 6–24 hours. Protein and mRNA expression of UCP‐1, PPARg, and PGC1a were measured. mRNA analysis of other brown and beige maker genes (PRDM16, Cidea, and CD137), and white marker genes (IGFBP3), as well as mitochondrial related genes (Nrf and Cox4a) were also measured. For mechanistic exploration, PPARg transactivation reporter gene assays were conducted. In addition, an adenovirus mediated PPARg knock down (KD) in 3T3‐L1 cells was generated. We report that similar to ROSI, INDO significantly induced UCP‐1 mRNA expression in 3T3‐L1 cells under basal and ISO stimulated condition compared to the controls (p<0.05 for INDO at 10, 20, 50 μM under basal condition and INDO at 2, 5, 10, 20 μM under ISO stimulated condition). INDO also significantly induced mRNA expression of Nrf and PGC1a (p<0.05). INDO also significantly induced UCP1 and PGC1α protein expression under basal condition (p<0.05 INDO at 10 and 20 μM) while suppressing PPARg protein expression (p<0.05 INDO at 10 and 20 μM). Mechanistically, INDO significantly activated PPARg in 3T3‐L1 cells (p<0.01 for INDO at 20 and 50 μM), which is consistent with the previous report in C3H10T1/2 cells. Moreover, upregulation of UCP1 and other brown markers by INDO were decreased in PPARg KD cells compared to non‐targeting adenovirus infected control cells. Furthermore, we explored INDO's effects on promoting brown adipogenesis in human brown fat cells. We report that INDO significantly induced PPARg, PGC1α, and DIO2 at 20 μM (p<0.05). INDO also significantly induced UCP1 mRNA and protein expression (p<0.01 for INDO at 20 μM for mRNA and p<0.05 for INDO at 2, 5, 10 μM, for protein). Taken together, despite INDO's potential systemic side‐effects, our results reveal a novel capacity for INDO to induce browning and brown adipogenesis through acting as a PPARg agonist.Support or Funding InformationThe work has been partially supported by NIH 1R15AT008733 award.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

СІРКОВОДНЕВА СИСТЕМА ПОСЛАБЛЮЄ УШКОДЖЕННЯ АДИПОЦИТІВ БРИЖІ У СТАРИХ ТВАРИН, ІНДУКОВАНІ ГІПЕРГЛІКЕМІЄЮ ТА СТРЕСОМ

Introduction. The mesentery is one of recently described separate organs which functions and its ability to protect injury are still unclear. Adipocytes are a part of mesentery (MAC), however, it is a little known about their age-related changes, reactive response during damage induced by hyperglycemia, stress, and their interaction. Hydrogen Sulfide (H2S) system is key endogenous cytoprotectvite system that operated by catalytic activities of Cystathionine-γ-lyase (CSE), Cystathionine-β-synthase (CBS), and Sulfite Oxidase (SUOX) but their role in adipocyte cytoprotection are still unknown. Aim. To evaluate the CBS, CSE, SUOX activities in the mesenterium and ultrastructural changes of MAC in aged rats fed with HSD, at stress induction, and modification of H2S synthesis by NaHS and hybrid nonsteroid anti-inflammatory drugs H2S-acytylsalicylic acid (H2S-ASA). Material and Methods: All experiments were carried out on the aged rats which divided to the control group (standard diet) and experimental groups (28-days hypercaloric high-carbohydrate diet, as HSD by V. Kozar, 2008) without and with acute stress by water-immobilization stress model by Takagi, 1964, and pretreated per os by: 1) control group by vehicle (1,0 ml of saline), rats from 2-8 groups with HSD for 2) 1,0 ml of saline; 3) NaHS in a dose of 100 мkmol/kg, 9 days; 4) 1,0 ml of saline and induction of stress; 5) NaHS at a dose of 100 мkmol/kg and induction of stress; 6) ASA at a dose of 10 mg/kg/day for 9 days, NaHS at a dose of 100 мkmol/kg, and induction of stress; 7) ASA,10 mg/kg/day, per 9 days; 8) H2S-ASA ( ATB-340), 17,5 mg/kg/day, per 9 days). Subcellular changes of MAC were detected by transmission electron microscopy (TEM). MAC CSE, CBS, SUOX activities were evaluated by standard biochemical methods. Results. In HSD group with NaHS endothelial and sub-endothelial structures destructions were absent, the nucleus of endothelial cells it was observed an uneven condensation of chromatin. Effect of hybrid H2S-ASA characterized as a protective action and MAC “slimming”. The use of H2S-ASA showed an increase on 15% of the general activity of H2S/CSE and H2S/CBS vs ASA pretreatment (p<0.05). The use of aspirin and NaHS has shown an increase on 67% H2S/CSE and H2S/CBS activities in HSD rats vs saline group. SUOX activity was 5.27 nmol/min•mg in control, HSD rats – 4.05 nmol/min•mg; with NaHS HSD and stress were approximately same as control. Conclusions: This study suggests an important role for CSE/H2S pathway in the mesenteric adipocyte cellar survival and control cytoprotection. High expression activities in CSE/H2S and SUOX pathways in mesenteric adipocytes compromised by age, hyperglycemia might be associated with the development of low-grade inflammation and may be a potential therapeutic target for obesity treatment. H2S-ASA could be an effective tool for prevention of age-related inflammation and exert defensive effect against hyperglycemia.

Differential effects of selective agonists of neuromedin U1 and U2 receptors in obese and diabetic mice.

Neuromedin U (NmU) may be a novel target for obesity treatment owing to its anorectic and energy expenditure enhancing effects. Although two receptors, NMU1 and NMU2, are both responsible for the NmU-mediated anti-obesity effects, the receptor agonist with the most appropriate profiles for treating obesity and diabetes in terms of efficacy and safety is as yet unknown. Thus, we developed and evaluated novel NMU1/2 receptor-selective agonists. Efficacy and safety were assessed in mice with diet-induced obesity (DIO) and those with leptin-deficient diabetes (ob/ob) through repeated peripheral administration of selective agonists to NMU1 (NMU-6102) and NMU2 (NMU-2084), along with non-selective NMU1/2 agonists (NMU-0002 and NMU-6014). We also performed immunohistochemistry for c-Fos protein expression in the brain to probe their mechanisms of action. Although both non-selective NMU1/2 agonists and the NMU2-selective agonist had high efficacy compared with the NMU1-selective agonist, only the NMU2-selective agonist led to relatively low adverse effects, such as diarrhoea, in DIO mice. However, the non-selective NMU1/2 agonist and the NMU1-selective agonist, but not the NMU2-selective agonist, were effective in diabetic ob/ob mice. Mechanistically, NMU2-selective agonists preferentially activate pro-opiomelanocortin neurons in the hypothalamic arcuate nucleus but not in the paraventricular nucleus. These results suggest that an NMU2 receptor-selective agonist may be a well-balanced drug for the treatment of obesity and that an NMU1 receptor-selective agonist may also be beneficial for treating obesity and diabetes once its side effects are minimized.

A miR-327\u2013FGF10\u2013FGFR2-mediated autocrine signaling mechanism controls white fat browning

Understanding the molecular mechanisms regulating beige adipocyte formation may lead to the development of new therapies to combat obesity. Here, we report a miRNA-based autocrine regulatory pathway that controls differentiation of preadipocytes into beige adipocytes. We identify miR-327 as one of the most downregulated miRNAs targeting growth factors in the stromal-vascular fraction (SVF) under conditions that promote white adipose tissue (WAT) browning in mice. Gain- and loss-of-function experiments reveal that miR-327 targets FGF10 to prevent beige adipocyte differentiation. Pharmacological and physiological β-adrenergic stimulation upregulates FGF10 levels and promotes preadipocyte differentiation into beige adipocytes. In vivo local delivery of miR-327 to WATs significantly compromises the beige phenotype and thermogenesis. Contrarily, systemic inhibition of miR-327 in mice induces browning and increases whole-body metabolic rate under thermoneutral conditions. Our data provide mechanistic insight into an autocrine regulatory signaling loop that regulates beige adipocyte formation and suggests that the miR-327–FGF10–FGFR2 signaling axis may be a therapeutic targets for treatment of obesity and metabolic diseases.

Sympathetic neuron-associated macrophages contribute to obesity by importing and metabolizing norepinephrine.

The cellular mechanism(s) linking macrophages to norepinephrine (NE)-mediated regulation of thermogenesis have been a topic of debate. Here we identify sympathetic neuron-associated macrophages (SAMs) as a population of cells that mediate clearance of NE via expression of solute carrier family 6 member 2 (SLC6A2), an NE transporter, and monoamine oxidase A (MAOA), a degradation enzyme. Optogenetic activation of the sympathetic nervous system (SNS) upregulates NE uptake by SAMs and shifts the SAM profile to a more proinflammatory state. NE uptake by SAMs is prevented by genetic deletion of Slc6a2 or inhibition of the encoded transporter. We also observed an increased proportion of SAMs in the SNS of two mouse models of obesity. Genetic ablation of Slc6a2 in SAMs increases brown adipose tissue (BAT) content, causes browning of white fat, increases thermogenesis, and leads to substantial and sustained weight loss in obese mice. We further show that this pathway is conserved, as human sympathetic ganglia also contain SAMs expressing the analogous molecular machinery for NE clearance, which thus constitutes a potential target for obesity treatment.

Farnesol Has an Anti-obesity Effect in High-Fat Diet-Induced Obese Mice and Induces the Development of Beige Adipocytes in Human Adipose Tissue Derived-Mesenchymal Stem Cells

Brown adipocytes dissipate energy as heat and hence have an important therapeutic capacity for obesity. Development of brown-like adipocytes (also called beige) is also another attractive target for obesity treatment. Here, we investigated the effect of farnesol, an isoprenoid, on adipogenesis in adipocytes and on the browning of white adipose tissue (WAT) as well as on the weight gain of high-fat diet (HFD)-induced obese mice. Farnesol inhibited adipogenesis and the related key regulators including peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α through the up-regulation of AMP-activated protein kinase in 3T3-L1 murine adipocytes and human adipose tissue-derived mesenchymal stem cells (hAMSCs). Farnesol markedly increased the expression of uncoupling protein 1 and PPARγ coactivator 1 α in differentiated hAMSCs. In addition, farnesol limited the weight gain in HFD obese mice and induced the development of beige adipocytes in both inguinal and epididymal WAT. These results suggest that farnesol could be a potential therapeutic agent for obesity treatment.

Pharmacological inhibition of ALDH1A enzymes suppresses weight gain in a mouse model of diet-induced obesity

Retinoic acid (RA) is known to play a role in weight regulation. Because mice without ALDH1A1, a major RA synthesizing enzyme, are resistant to diet-induced obesity, we tested a hypothesis that pharmacological inhibition of RA synthesis can suppress weight gain in a murine model of diet-induced obesity. C57BL/6J male mice were fed a high fat diet (HFD) for 8 weeks to induce obesity and then randomized to a HFD with or without WIN 18,446, an RA synthesis inhibitor, for an additional 9 weeks. Body weight, body composition, energy expenditure, activity, and food intake were measured. Levels of retinoids, lipids, and genes involved in the metabolism of retinoid and lipids were also determined. s Mice treated with WIN 18,446 gained significantly less weight and had decreased adipose tissue weight, adipocyte size, and macrophage infiltration in adipose tissue. In addition, we observed higher UCP1 expression in adipose tissues and decreased expression of RA responsive genes and genes involved in fatty acid synthesis in the livers and lungs of mice treated with WIN 18,446. Pharmacological suppression of RA synthesis via inhibition of ALDH1A1 may be a potential target for treatment of obesity.

Quantifying Biochemical Alterations in Brown and Subcutaneous White Adipose Tissues of Mice Using Fourier Transform Infrared Widefield Imaging.

Stimulating increased thermogenic activity in adipose tissue is an important biological target for obesity treatment, and label-free imaging techniques with the potential to quantify stimulation-associated biochemical changes to the adipose tissue are highly sought after. In this study, we used spatially resolved Fourier transform infrared (FTIR) imaging to quantify biochemical changes caused by cold exposure in the brown and subcutaneous white adipose tissues (BAT and s-WAT) of 6 week-old C57BL6 mice exposed to 30°C (N = 5), 24°C (N = 5), and 10°C (N = 5) conditions for 10 days. Fat exposed to colder temperatures demonstrated greater thermogenic activity as indicated by increased messenger RNA expression levels of a panel of thermogenic marker genes including uncoupling protein 1 (UCP-1) and Dio2. Protein to lipid ratio, calculated from the ratio of the integrated area from 1,600 to 1,700 cm−1 (amide I) to the integrated area from 2,830 to 2,980 cm−1 (saturated lipids), was elevated in 10°C BAT and s-WAT compared to 24°C (p = 0.004 and p < 0.0001) and 30°C (p = 0.0033 and p < 0.0001). Greater protein to lipid ratio was associated with greater UCP-1 expression level in the BAT (p = 0.021) and s-WAT (p = 0.032) and greater Dio2 expression in s-WAT (p = 0.033). The degree of unsaturation, calculated from the ratio of the integrated area from 2,992 to 3,020 cm−1 (unsaturated lipids) to the integrated area from 2,830 to 2,980 cm−1 (saturated lipids), showed stepwise decreases going from colder-exposed to warmer-exposed BAT. Complementary 1H NMR measurements confirmed the findings from this ratio in BAT. Principal component analysis applied to FTIR spectra revealed pronounced differences in overall spectral characteristics between 30, 24, and 10°C BAT and s-WAT. Spatially resolved FTIR imaging is a promising technique to quantify cold-induced biochemical changes in BAT and s-WAT in a label-free manner.

Neuromedin B receptor: role in adipogenesis and a possible target for obesity treatment

Neuromedin B receptor: role in adipogenesis and a possible target for obesity treatment

Nanoparticles encapsulated with resveratrol induce browning of white adipocytes

Functional brown adipose tissue, including classical brown adipocytes and brown‐like or beige adipocytes, which develop within white adipose tissue (WAT) in response to various stimuli, has emerged as novel targets for obesity treatment and prevention. Through browning process, beige adipocytes are induced to express UCP‐1 and become capable of thermogenesis. Identifying nutritional strategies that increase UCP‐1 and induce browning within white adipocytes is key to unlocking browning potential. Resveratrol (Res) is a well‐known polyphenol found in the skins of grapes and other fruits such as berries with anti‐inflammatory, antioxidant, and anti‐carcinogenic properties. Nanotechnology has shown great promise in encapsulating polyphenols, such as Res, to increase their solubility and stability, consequently, bioactivities. In this study, Res encapsulated in biocompatible and biodegradable lipid nanoparticles (Nano‐Res) or liposomes (Lipo‐Res), along with free Res (Res) and their respective controls (Nano‐Void or Lipo‐Void respectively) were tested at three doses (5, 10, 20 μM) in 3T3‐L1 mouse pre‐adipocytes in a 7‐day differentiation process. At the end of differentiation, the cells were subjected to thermogenic activation by isoproterenol (ISO), a β‐adrenergic receptor agonist, or the control for 6 hours. Cytotoxicity of the treatments and mRNA expression of UCP‐1, brown (PPARγ, PGC1α, PRDM16, and Cidea), beige (CD137 and Tmem26), and white marker genes (IGFBP3), as well as mitochondria related genes (Cox4a, Uqrch, Nrf, and Tfam) were measured. We report that none of the treatments showed signs of cytotoxicity at 24‐hrs and minimal toxicity at 72‐hrs. Lipo‐Res and Nano‐Res significantly induced dose‐dependent increase of UCP‐1 mRNA expression under ISO stimulated conditions compared to the controls (p&lt;0.05). At the low dose of 5 μM Lipo‐Res significantly stimulated UCP‐1 to a higher level than free Res (p&lt;0.05). Under both basal (non‐ISO stimulated) and ISO stimulated conditions, both Lipo‐Res and Nano‐Res dose‐dependently decreased WAT marker IGFBP3 mRNA (p&lt;0.05) while simultaneously increasing mRNA of beige marker CD137 and brown markers PRDM16 (p&lt;0.05). Interestingly, Lipo‐Res significantly increased Cidea expression in ISO‐stimulated conditions (p&lt;0.05); however, Nano‐Res (and Nano‐Void) decreased Cidea expression (p&lt;0.05). Other beige markers and mitochondrial structural genes were increased by encapsulated Res, but did not reach significance compared to the controls. Taken together, our results demonstrate that nanoencapsulation enhances Res's bioactivities in inducing browning of white adipocytes. Our results point towards promising nutritional strategies for obesity treatment and prevention.Support or Funding InformationThe work has been supported by NIH 1R15AT008733 award.

Phillyrin lowers body weight in obese mice via the modulation of PPAR/-ANGPTL 4 pathway

Previous investigations have shown that the peroxisome proliferator activated receptor beta/delta (PPAR<beta>/<delta>)-angiopoietin-like protein 4 (ANGPTL4) pathways may be a new pharmacologic target for treatment of obesity. The present study was conducted to test the effect of phillyrin, ‎a glucoside, on obesity in mice. Fifty mice were randomly divided into 5 groups (n=10): control group (C57BL/6J mice), obese mice group, two groups of obese mice treated with phillyrin (15 or 45mg/kg/day), one group of obese mice treated with PPAR<beta>/<delta> agonist GW0742 (3mg/kg/day). Twelve weeks after treatment, body weight, liver weight, fat weight, lipid levels in the liver, serum levels of tumour necrosis factor-<alpha>(TNF-<alpha>), leptin, and insulin, expression of PPAR<beta>/<delta>, ANGPTL4, and AMP-activated protein kinase (AMPK) were determined. Treatment with phillyrin (15 or 45mg/kg) significantly decreased body weight, liver weight, fat weight, hepatic total cholesterol, free fatty acid, and triglyceride concentrations, serum levels of TNF-<alpha>, leptin, and insulin concomitantly with up-regulated expression of PPAR<beta>/<delta>, ANGPTL4, and p-AMPK-<alpha>. In addition, GW0742 has similar effect of phillyrin. The present results suggest that phillyrin could regulate the PPAR<beta>/<delta>-ANGPTL 4 pathway to lower body weight in obese C57BL/6J mice.

A Selective Bombesin Receptor Subtype 3 Agonist Promotes Weight Loss in Male Diet-Induced–Obese Rats With Circadian Rhythm Change

Bombesin receptor subtype 3 (BRS-3) is an orphan G protein-coupled receptor. Based on the obese phenotype of male BRS-3-deficient mice, BRS-3 has been considered an attractive target for obesity treatment. Here, we developed a selective BRS-3 agonist (compound-A) and evaluated its antiobesity effects. Compound-A showed anorectic effects and enhanced energy expenditure in diet-induced-obese (DIO)-F344 rats. Moreover, repeated oral administration of compound-A for 7 days resulted in a significant body weight reduction in DIO-F344 rats. We also evaluated compound-A for cardiovascular side effects using telemeterized Sprague-Dawley (SD) rats. Oral administration of compound-A resulted in transient blood pressure increases in SD rats. To investigate the underlying mechanisms of BRS-3 agonist effects, we focused on the suprachiasmatic nucleus (SCN), the main control center of circadian rhythms in the hypothalamus, also regulating sympathetic nervous system. Compound-A significantly increased the messenger RNA expression of Brs-3, c-fos, and circadian rhythm genes in SCN of DIO-F344 rats. Because SCN also controls the hypothalamic-pituitary-adrenal (HPA) axis, we evaluated the relationship between BRS-3 and the HPA axis. Oral administration of compound-A caused a significant increase of plasma corticosterone levels in DIO-F344 rats. On this basis, energy expenditure enhancement by compound-A may be due to a circadian rhythm change in central and peripheral tissues, enhancement of peripheral lipid metabolism, and stimulation of the sympathetic nervous system. Furthermore, the blood pressure increase by compound-A could be associated with sympathetic nervous system stimulation via SCN and elevation of plasma corticosterone levels through activation of the HPA axis.

New Targets for Drug Treatment of Obesity.

Antiobesity medical management has shown unsatisfactory results to date in terms of efficacy, safety, and long-term maintenance of weight loss. This poor performance could be attributed to the complexity of appetite regulation mechanisms; the serious drug side effects; and, crucially, the lack of profile-matching treatment strategies and individualized, multidisciplinary follow-up. Nevertheless, antiobesity pharmacotherapy remains a challenging, exciting field of intensive scientific interest. According to the latest studies, the future of bariatric medicine lies in developing drugs acting at multiple levels of the brain-gut axis. Currently, research is focused on the generation of combination treatments based on gut hormones in a way that mimics changes underlying surgically induced weight loss, in addition to centrally acting agents; these aim to restore energy balance disruptions and enhance energy expenditure. Collectively, the pharmacological resolution of obesity could potentially be achieved with combination regimens targeting different molecules and levels of the energy homeostasis system, in parallel with matching patients' needs, resulting in a favorable metabolic profile.

Rimonabant improves metabolic parameters partially attributed to restoration of high voltage-activated Ca2+ channels in skeletal muscle in HFD-fed mice.

Cannabinoid type 1 receptor (CB1R) inhibition tends to be one of the promising strategies for the treatment of obesity and other related metabolic disorders. Although CB1R inhibition may cause adverse psychiatric effects including depression and anxiety, the investigation of the role of peripheral CB1R on weight loss and related metabolic parameters are urgently needed. We first explored the effect of rimonabant, a selective CB1R antagonist/inverse agonist, on some metabolic parameters in high fat-diet (HFD)-induced obesity in mice. Then, real-time PCR and electrophysiology were used to explore the contribution of high voltage-activated Ca2+ channels (HVACCs), especially Cav1.1, on rimonabant's effect in skeletal muscle (SM) in HFD-induced obesity. Five-week HFD feeding caused body weight gain, and decreased glucose/insulin tolerance in mice compared to those in the regular diet group (P<0.05), which was restored by rimonabant treatment compared to the HFD group (P<0.05). Interestingly, HVACCs and Cav1.1 were decreased in soleus muscle cells in the HFD group compared to the control group. Daily treatment with rimonabant for 5 weeks was shown to counter such decrease (P<0.05). Collectively, our findings provided a novel understanding for peripheral CB1R's role in the modulation of body weight and glucose homeostasis and highlight peripheral CB1R as well as Cav1.1 in the SM as potential targets for obesity treatment.

Isolation, Primary Culture, and Differentiation of Preadipocytes from Mouse Brown Adipose Tissue.

Evolutionally, brown adipose tissue (BAT) is developed for nonshivering thermogenesis to prevent hypothermia. BAT has a high capacity to dissipate chemical energy generated from metabolism of nutrients for heat production. Therefore when BAT is activated, nutrients are "burned' instead of being stored. This feature makes BAT an attractive target for obesity treatment. To investigate BAT function and regulation, brown adipocyte culturing is indispensable. This chapter describes a detailed protocol for isolation, primary culture, and differentiation of preadipocytes from mouse BAT. The preadipocytes can be used for investigating the regulation of brown fat cell differentiation. The differentiated brown adipocytes maintain major BAT features including high expression of uncoupling protein-1 and can be used to study BAT biology and pharmacology.

Spatial Organization of Functional Groups on Bioactive Supramolecular Glycopeptide Nanofibers for Differentiation of Mesenchymal Stem Cells (MSCs) to Brown Adipogenesis.

Spatial organization of bioactive moieties in biological materials has significant impact on the function and efficiency of these systems. Here, we demonstrate the effect of spatial organization of functional groups including carboxylate, amine, and glucose functionalities by using self-assembled peptide amphiphile (PA) nanofibers as a bioactive scaffold. We show that presentation of bioactive groups on glycopeptide nanofibers affects mesenchymal stem cells (MSCs) in a distinct manner by means of adhesion, proliferation, and differentiation. Strikingly, when the glutamic acid is present in the glycopeptide backbone, the PA nanofibers specifically induced differentiation of MSCs into brown adipocytes in the absence of any differentiation medium as shown by lipid droplet accumulation and adipogenic gene marker expression analyses. This effect was not evident in the other glycopeptide nanofibers, which displayed the same functional groups but with different spatial organization. Brown adipocytes are attractive targets for obesity treatment and are found in trace amounts in adults, which also makes this specific glycopeptide nanofiber system an attractive tool to study molecular pathways of brown adipocyte formation.

The Role of the Vagal Nucleus Tractus Solitarius in the Therapeutic Effects of Obesity Surgery and Other Interventional Therapies on Type 2 Diabetes

The current treatment for obesity-related type 2 diabetes is not able to achieve sufficient metabolic control. New remission prospects have been offered through bariatric surgery and other interventional therapies. The aim of the study is to illustrate the mechanism by which such therapies affect the autonomic system, in particular the afferent vagal activity. The first and most important terminal of this activity is the brainstem vagal nucleus tractus solitarius. Its function, on which the vagal efferent inputs that control the splanchnic organs depend, is conditioned by the level of synaptic transmission within it. In conclusion, on the basis of such a view, a selective pharmacological modulation of such transmission as the target for future medical treatment of obesity and related type 2 diabetes is proposed.

Neuronal Rap1 Regulates Energy Balance, Glucose Homeostasis, and Leptin Actions

The CNS contributes to obesity and metabolic disease; however, the underlying neurobiological pathways remain to be fully established. Here, we show that the small GTPase Rap1 is expressed in multiple hypothalamic nuclei that control whole-body metabolism and is activated in high-fat diet (HFD)-induced obesity. Genetic ablation of CNS Rap1 protects mice from dietary obesity, glucose imbalance, and insulin resistance in the periphery and from HFD-induced neuropathological changes in the hypothalamus, including diminished cellular leptin sensitivity and increased endoplasmic reticulum (ER) stress and inflammation. Furthermore, pharmacological inhibition of CNS Rap1 signaling normalizes hypothalamic ER stress and inflammation, improves cellular leptin sensitivity, and reduces body weight in mice with dietary obesity. We also demonstrate that Rap1 mediates leptin resistance via interplay with ER stress. Thus, neuronal Rap1 critically regulates leptin sensitivity and mediates HFD-induced obesity andhypothalamic pathology and may represent a potential therapeutic target for obesity treatment.

Discovery of N-(1-(3-(4-phenoxyphenyl)-1,2,4-oxadiazol-5-yl)ethyl)acetamides as novel acetyl-CoA carboxylase 2 (ACC2) inhibitors with peroxisome proliferator-activated receptor α/δ (PPARα/δ) dual agonistic activity

Acetyl-CoA carboxylases (ACCs) catalyze a critical step in de novo lipogenesis, and are considered as promising targets for treatment of obesity, dyslipidemia and type 2 diabetes mellitus. On the other hand, peroxisome proliferator-activated receptors (PPARs) are well-established therapeutic targets for these metabolic syndrome-related diseases. Therefore, we considered that dual modulators of ACC and PPARs would be promising candidates as therapeutic agents. Here, we designed a series of acetamides based on the molecular similarity between ACC inhibitors and PPAR agonists. Screening of the synthesized compounds identified N-(1-(3-(4-phenoxyphenyl)-1,2,4-oxadiazol-5-yl)ethyl)acetamides as novel ACC2 inhibitors with PPARα/PPARδ dual agonistic activity. Structure–activity relationship studies and further structural elaboration afforded compounds with distinct activity profiles. Our findings should be helpful for the discovery of candidate agents with an appropriate balance of ACC-inhibitory and PPAR-activating activities for therapeutic lipid control.