Cocoa extract induces browning of white adipocytes and improves glucose intolerance in mice fed a high-fat diet.

Cocoa extract (CE) offers several health benefits, such as anti-obesity and improved glucose intolerance. However, the mechanisms remain unclear. Adipose tissue includes white adipose tissue (WAT) and brown adipose tissue. Brown adipose tissue leads to body fat reduction by metabolizing lipids to heat via uncoupling protein 1 (UCP1). The conversion of white adipocytes into brown-like adipocytes (beige adipocytes) is called browning, and it contributes to the anti-obesity effect and improved glucose tolerance. This study aimed to evaluate the effect of CE on glucose tolerance in terms of browning. We found that dietary supplementation with CE improved glucose intolerance in mice fed a high-fat diet, and it increased the expression levels of Ucp1 and browning-associated gene in inguinal WAT. Furthermore, in primary adipocytes of mice, CE induced Ucp1 expression through ß3-adrenergic receptor stimulation. These results suggest that dietary CE improves glucose intolerance by inducing browning in WAT.

Activation of ß-adrenergic receptor signaling prevents glucocorticoid-induced obesity and adipose tissue dysfunction in male mice.

Elevated serum concentrations of glucocorticoids (GCs) result in excessive lipid accumulation in white adipose tissue (WAT) as well as dysfunction of thermogenic brown adipose tissue (BAT), ultimately leading to the development of obesity and metabolic disease. Here, we hypothesized that activation of the sympathetic nervous system either via cold exposure or the use of a selective ß3-adrenergic receptor (ß3-AR) agonist alleviates the adverse metabolic effects of chronic GC exposure in rodents. To this end, male 10-wk-old C57BL/6NRj mice were treated with corticosterone via drinking water or placebo for 4 wk while being maintained at 29°C (thermoneutrality), 22°C (room temperature), or 13°C (cold temperature); in a follow-up study mice received a selective ß3-AR agonist or placebo with and without corticosterone while being maintained at room temperature. Body weight and food intake were monitored throughout the study. Histological and molecular analyses were performed on white and brown adipose depots. Cold exposure not only preserved the thermogenic function of brown adipose tissue but also reversed GC-induced lipid accumulation in white adipose tissue and corrected GC-driven obesity, hyperinsulinemia, and hyperglycemia. The metabolic benefits of cold exposure were associated with enhanced sympathetic activity in adipose tissue, thus potentially linking an increase in sympathetic signaling to the observed metabolic benefits. In line with this concept, chronic administration of a selective ß3-AR agonist reproduced the beneficial metabolic effects of cold adaption during exposure to exogenous GCs. This preclinical study demonstrates the potential of ß3-AR as a therapeutic target in the management and prevention of GC-induced metabolic disease.NEW & NOTEWORTHY This preclinical study in mice shows that the ß3-adrenergic receptor can be a potential therapeutic approach to counteracting glucocorticoid (GC)-induced obesity and metabolic dysfunction. Both cold acclimation and ß3-adrenergic receptor stimulation in a mouse model of excess glucocorticoids were adequate in not only preventing obesity, adiposity, and adipose tissue dysfunction but also correcting hyperinsulinemia, hyperleptinemia, and dyslipidemia.

Tisochrysis lutea F&M-M36 Mitigates Risk Factors of Metabolic Syndrome and Promotes Visceral Fat Browning through ß3-Adrenergic Receptor/UCP1 Signaling.

Pre-metabolic syndrome (pre-MetS) may represent the best transition phase to start treatments aimed at reducing cardiometabolic risk factors of MetS. In this study, we investigated the effects of the marine microalga Tisochrysis lutea F&M-M36 (T. lutea) on cardiometabolic components of pre-MetS and its underlying mechanisms. Rats were fed a standard (5% fat) or a high-fat diet (20% fat) supplemented or not with 5% of T. lutea or fenofibrate (100 mg/Kg) for 3 months. Like fenofibrate, T. lutea decreased blood triglycerides (p < 0.01) and glucose levels (p < 0.01), increased fecal lipid excretion (p < 0.05) and adiponectin (p < 0.001) without affecting weight gain. Unlike fenofibrate, T. lutea did not increase liver weight and steatosis, reduced renal fat (p < 0.05), diastolic (p < 0.05) and mean arterial pressure (p < 0.05). In visceral adipose tissue (VAT), T. lutea, but not fenofibrate, increased the ß3-adrenergic receptor (ß3ADR) (p < 0.05) and Uncoupling protein 1 (UCP-1) (p < 0.001) while both induced glucagon-like peptide-1 receptor (GLP1R) protein expression (p < 0.001) and decreased interleukin (IL)-6 and IL-1ß gene expression (p < 0.05). Pathway analysis on VAT whole-gene expression profiles showed that T. lutea up-regulated energy-metabolism-related genes and down-regulated inflammatory and autophagy pathways. The multitarget activity of T. lutea suggests that this microalga could be useful in mitigating risk factors of MetS.

Potato protease inhibitor II prevents obesity by inducing browning of white adipose tissue in mice via ß3 adrenergic receptor signaling pathway.

There are currently few effective and safe pharmacologic means for inducing beige adipogenesis in humans. This study highlights the role of potato protease inhibitor II (PPI II) in regulating the browning of adipose tissue. The in vitro results showed that PPI II increased the expression of the uncoupling protein 1 (UCP1) protein and gene and beige-specific genes, including Cd137, Cited1, Tbx1, and Tmem26 in vitro. PPI II treatment for three months in diet-induced obesity mice increased the levels of the UCP1 protein in white adipose tissue, causing elevated energy expenditure, thus preventing obesity and improving glucose tolerance. Mechanistic studies further revealed that PPI II regulated the abundance and activity of ß3 adrenergic receptor (ß3 -AR) in white adipocytes. Chemical-inhibition experiments revealed the crucial role of ß3 -AR-dependent protein kinase A (PKA)-p38 kinase (p38)/extracellular signal-related kinase1/2 (ERK1/2) signaling in PPI II-mediated browning program of white adipose tissues. In summary, our findings highlight the role of PPI II in beige adipocyte differentiation and thermogenesis and provide new insights into its use in preventing obesity.

Differential S-palmitoylation of the human and rodent ß3-adrenergic receptors.

With few reported exceptions, G protein-coupled receptors (GPCRs) are modified by Cys palmitoylation (S-palmitoylation). In multiple GPCRs, S-palmitoylation targets a canonical site within the C-terminal cytoplasmic tail adjacent to the C terminus of the seventh transmembrane domain, but modification of additional sites is exemplified by the ß-adrenergic receptors (ßARs). The ß1AR is S-palmitoylated at a second, more distal site within the C-terminal tail, and the ß2AR is modified at a second site within the third intracellular loop, neither of which is conserved in other ßAR isoforms. The functional roles of S-palmitoylation of disparate sites are incompletely characterized for any GPCR family. Here, we describe S-palmitoylation of the ß3AR. We compared mouse and human ß3ARs and found that both were S-palmitoylated at the canonical site within the C-terminal tail, Cys-358 and Cys-361/363 in mouse and human ß3ARs, respectively. Surprisingly, the human ß3AR was S-palmitoylated at two additional sites, Cys-153 and Cys-292 within the second and third intracellular loops, respectively. Cys-153 is apparently unique to the human ß3AR, and Cys-292 is conserved primarily in primates. Mutational substitution of C-tail Cys in human but not mouse ß3ARs resulted in diminished ligand-induced cAMP production. Substitution of Cys-153, Cys-292, or Cys-361/363 within the human ß3AR diminished membrane-receptor abundance, but only Cys-361/363 substitution diminished membrane-receptor half-life. Thus, S-palmitoylation of different sites differentially regulates the human ß3AR, and differential S-palmitoylation distinguishes human and rodent ß3ARs, potentially contributing to species-specific differences in the clinical efficacy of ß3AR-directed pharmacological approaches to disease.

The protective effects of the ß3 adrenergic receptor agonist BRL37344 against liver steatosis and inflammation in a rat model of high-fat diet-induced nonalcoholic fatty liver disease (NAFLD).

BACKGROUND: Our objective was to investigate the efficacy of the beta-3 adrenergic receptor (ß3-AR) agonist BRL37344 for the prevention of liver steatosis and inflammation associated with nonalcoholic fatty liver disease (NAFLD). METHODS: Four groups were established: a control group (given a standard diet), a high-fat diet (HFD) group, an HFD + ß3-AR agonist (ß3-AGO) group, and an HFD + ß3-AR antagonist (ß3-ANT) group. All rats were fed for 12 weeks. The ß3-AR agonist BRL37344 and the antagonist L748337 were administered for the last 4 weeks with Alzet micro-osmotic pumps. The rat body weights (g) were measured at the end of the 4th, 8th, and 12th weeks. At the end of the 12th week, the liver weights were measured. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed with a Hitachi automatic analyzer. The lipid levels of the triglycerides (TGs), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) and the concentrations of free fatty acids (FFAs) were also measured. An oil red O kit was used to detect lipid droplet accumulation in hepatocytes. Steatosis, ballooning degeneration and inflammation were histopathologically determined. The protein and mRNA expression levels of ß3-AR, peroxisome proliferator-activated receptor-alpha (PPAR-α), peroxisome proliferator-activated receptor-gamma (PPAR-γ), mitochondrial carnitine palmitoyltransferase-1 (mCPT-1), and fatty acid translocase (FAT)/CD36 were measured by western blot analysis and RT-qPCR, respectively. RESULTS: After treatment with the ß3-AR agonist BRL37344 for 4 weeks, the levels of ALT, AST, TGs, TC, LDL-C and FFAs were decreased in the NAFLD model group compared with the HFD group. Body and liver weights, liver index values and lipid droplet accumulation were lower in the HFD + ß3-AGO group than in the HFD group. Decreased NAFLD activity scores (NASs) also showed that liver steatosis and inflammation were ameliorated after treatment with BRL37344. Moreover, the ß3-AR antagonist L748337 reversed these effects. Additionally, the protein and gene expression levels of ß3-AR, PPAR-α, and mCPT-1 were increased in the HFD + ß3-AGO group, whereas those of PPAR-γ and FAT/CD36 were decreased. CONCLUSION: The ß3-AR agonist BRL37344 is beneficial for reducing liver fat accumulation and for ameliorating liver steatosis and inflammation in NAFLD. These effects may be associated with PPARs/mCPT-1 and FAT/CD36.

ß3-Adrenergic receptor blockade reduces mortality in endotoxin-induced heart failure by suppressing induced nitric oxide synthase and saving cardiac metabolism.

The ß3-adrenergic receptor (ß3AR) is related to myocardial fatty acid metabolism and its expression has been implicated in heart failure. In this study, we investigated the role of ß3AR in sepsis-related myocardial dysfunction using lipopolysaccharide (LPS)-induced endotoxemia as a model of cardiac dysfunction. We placed mice into three treatment groups and treated each with intraperitoneal injections of the ß3AR agonist CL316243 (CL group), the ß3AR antagonist SR59230A (SR group), or normal saline (NS group). Survival rates were significantly improved in the SR group compared with the other treatment groups. Echocardiography analyses revealed cardiac dysfunction within 6-12 h of LPS injections, but the outcome was significantly better for the SR group. Myocardial ATP was preserved in the SR group but was decreased in the CL-treated mice. Additionally, quantitative PCR analysis revealed that expression levels of genes associated with fatty acid oxidation and glucose metabolism were significantly higher in the SR group. Furthermore, the expression levels of mitochondrial membrane protein complexes were preserved in the SR group. Electron microscope studies showed significant accumulation of lipid droplets in the CL group. Moreover, inducible nitric oxide synthase (iNOS) protein expression and nitric oxide were significantly reduced in the SR group. The in vitro study demonstrated that ß3AR has an independent iNOS pathway that does not go through the nuclear factor-κB pathway. These results suggest that blockading ß3AR improves impaired energy metabolism in myocardial tissues by suppressing iNOS expression and recovers cardiac function in animals with endotoxin-induced heart failure.NEW & NOTEWORTHY Nitric oxide production through stimulation of ß3-adrenergic receptor (ß3AR) may improve cardiac function in cases of chronic heart failure. We demonstrated that the blockade of ß3AR improved mortality and cardiac function in endotoxin-induced heart failure. We also determined that LPS-induced inducible nitric oxide synthase has a pathway that is independent of nuclear factor-κB, which worsened cardiac metabolism and mortality in the acute phase of sepsis. Treatment with the ß3AR antagonist had a favorable effect. Thus, the blockade of ß3AR could offer a novel treatment for sepsis-related heart failure.

Adrenal cortex hypoxia modulates aldosterone production in heart failure.

Plasma aldosterone concentration increases in proportion to the severity of heart failure, even during treatment with renin-angiotensin system inhibitors. This study investigated alternative regulatory mechanisms of aldosterone production that are significant in heart failure. Dahl salt-sensitive rats on a high-salt diet, a rat model of heart failure with cardio-renal syndrome, had high plasma aldosterone levels and elevated ß3-adrenergic receptor expression in hypoxic zona glomerulosa cells. In H295R cells (a human adrenocortical cell line), hypoxia-induced ß3-adrenergic receptor expression. Hypoxia-mediated ß3-adrenergic receptor expression augmented aldosterone production by facilitating hydrolysis of lipid droplets though ERK-mediated phosphorylation of hormone-sensitive lipase, also known as cholesteryl ester hydrolase. Hypoxia also accelerated the synthesis of cholesterol esters by acyl-CoA:cholesterol acyltransferase, thereby increasing the cholesterol ester content in lipid droplets. Thus, hypoxia enhanced aldosterone production by zona glomerulosa cells via promotion of the accumulation and hydrolysis of cholesterol ester in lipid droplets. In conclusion, hypoxic zona glomerulosa cells with heart failure show enhanced aldosterone production via increased catecholamine responsiveness and activation of cholesterol trafficking, irrespective of the renin-angiotensin system.

Green tea improves the metabolism of peripheral tissues in ß3-adrenergic receptor-knockout mice.

Our goal was to establish the requirement of ß3 adrenoceptor (ß3Adr) for green tea (GT) effects on the energy metabolism of obese mice. This study was carried out in wild-type (WT) and ß3Adr knockout (KO) male mice fed with a standard diet or a high-fat diet (HFD/16 weeks) treated or not with GT (0.5 g/kg of body weight (BW)/12 weeks). GT-treatment attenuated final BW, BW gain, and adiposity index increased by HFD, improving insulin resistance (IR) and FGF21 level, without changing the food intake of WT mice. GT-treatment of ß3AdrKO mice attenuated only IR, denoting GT-effects independent of ß3Adr. We observed increased lipolysis accompanied by decreased adipocyte size in white adipose tissue (WAT) as well as browning of the subcutaneous WAT induced by GT in a way dependent on ß3Adr. In brown adipose tissue (BAT) mRNA levels of lipolytic/oxidative genes, including ß3Adr/Ucp1 and energy expenditure (EE) was increased by GT dependent on ß3Adr. GT-treatment increased adiponectin independent of ß3Adr. Also, independent of ß3Adr pathway GT promoted an increase in ß2Adr/Ucp1 mRNA levels and EE in BAT whereas; in the liver, GT has a dual role in increasing lipid synthesis and oxidation. These data lead us to suggest that GT uses ß3Adr pathway activation to achieve some of its beneficial health effects.

The effect of mirabegron on bladder blood flow in a rat model of bladder outlet obstruction.

PURPOSE: To evaluate the effects of mirabegron on bladder blood flow in a rat model of bladder outlet obstruction (BOO). METHODS: Adult female Sprague-Dawley rats were divided into three groups based on whether they underwent a sham operation (sham group) or an operation to establish partial BOO (BOO and BOO + mirabegron groups). The BOO + mirabegron group was treated with mirabegron (0.3 mg/kg/h, subcutaneously) for 14 days. Subsequently, we performed continuous cystometry, bladder blood flow measurements with a 2D laser blood flow imager, hematoxylin-eosin staining of the bladder tissue, and malondialdehyde (MDA) measurements in the bladder tissue. RESULTS: Cystometry revealed significantly higher peak pressure, more residual urine volume, and lower voiding efficiency in the BOO and BOO + mirabegron groups than in the sham group. The BOO + mirabegron group had significantly fewer non-voiding contractions (NVCs) than the BOO group, while the latter had more frequent NVCs than the sham group. The BOO and BOO + mirabegron groups had significantly decreased bladder blood flow than the sham group, whereas the BOO + mirabegron group showed significantly increased bladder blood flow than the BOO group. The bladder tissue in the BOO group contained more hypertrophic detrusor muscle compared to the sham group, while mirabegron treatment suppressed detrusor hypertrophy. The MDA levels were significantly higher in the BOO group than in the BOO + mirabegron and sham groups. CONCLUSION: Mirabegron treatment significantly improved BOO-induced bladder dysfunction through the amelioration of bladder blood flow.

Targeting ß3-adrenergic receptor signaling inhibits neuroblastoma cell growth via suppressing the mTOR pathway.

Neuroblastoma (NB), the most common extracranial solid tumor in childhood, always leads to an unfavorable prognosis. ß3-adrenergic receptor (ß3-AR) signaling plays an important role in lipid metabolism. Although previous studies have focused mainly on the role of ß2-AR in tumor cells; there are few studies about the cancer-related function of ß3-AR. Herein, we showed that ß3-AR expression was significantly increased in clinical NB tissue compared with that in the less malignant ganglioneuroma (GN) and ganglioneuroblastoma (GNB) tissues. Further cellular assays demonstrated that treatment of NB cells with SR59230A (a specific ß3-AR antagonist) suppressed NB cells growth and colony formation, and siRNA knockdown of ß3-AR expression also inhibited NB cell proliferation. The mechanistic study revealed that ß3-AR knockdown and SR59230A inhibited the phosphorylation and thereby the activation of the mTOR/p70S6K pathway. Activation of the mTOR pathway with the activator MHY1485 reversed the inhibitory effect of SR59230A on NB cell growth. Above all, our study clarifies a novel regulatory role of ß3-AR in NB cell growth and provides a potent therapeutic strategy for this disease by specific targeting of the ß3-AR pathway.

The influence of nebivolol on the activity of BRL 37344 - the ß3-adrenergic receptor agonist, in the animal model of detrusor overactivity.

AIMS: The cardiotoxic effects of antimuscarinics constitute a significant restriction in their application in elderly people. Overactive bladder syndrome pharmacotherapy using compounds with cardioprotective properties would seem an ideal solution. The main goal of the study was to assess the impacts of nebivolol (NEB) on the activity of BRL 37344 - ß3-adrenergic receptor (ß3AR) agonist, in the animal model of detrusor overactivity. As both these substances can impact on the cardiovascular system, their effect on the parameters of this system and diuresis was also examined. METHODS: Retinyl acetate (RA; 0.75%) solution was used to induce detrusor overactivity in female Wistar rats. BRL and/or NEB were administered intra-arterially during cystometry in a single dose (2.5 or 5, 0.05 or 0.1 mg/kg, respectively). In addition, a 24 hours measurement of heart rate, blood pressure, and urine production was carried out. RESULTS: NEB (0.05 mg/kg) and BRL (2.5 mg/kg) monotherapy proved to have no influence on the cystometric parameters of animals with RA-induced detrusor overactivity. NEB at 0.1 mg/kg resulted in a drop in the detrusor overactivity index, similarly to BRL at 5 mg/kg. Coadministration of NEB and BRL, both at ineffective doses, decreased the detrusor overactivity index and ameliorated the nonvoiding contractions. ß3AR stimulation proved to induce tachycardia and hypertension. NEB at 0.05 mg/kg proved to ameliorate detrusor overactivity and have preventive properties against adverse cardiovascular effects of the ß3AR agonist. CONCLUSIONS: The combined application of the ß3AR agonist and NEB may improve detrusor overactivity without affecting the heart rate, blood pressure, and urine production.

The Trend of ß3-Adrenergic Receptor in the Development of Septic Myocardial Depression: A Lipopolysaccharide-Induced Rat Septic Shock Model.

Septic shock with low cardiac output is very common in children. However, the mechanism underlying myocardial depression is unclear. The role of ß3-AR in the development of myocardial depression in sepsis is unknown. In the present study, we generated an adolescent rat model of hypodynamic septic shock induced by lipopolysaccharide (LPS). Neonatal cardiomyocytes were also treated with LPS to mimic myocardial depression in sepsis, which was confirmed via an in vivo left ventricular hemodynamic study, and measurements of contractility and the Ca2+ transient in isolated adolescent and neonatal cardiomyocytes. After 16 h of LPS treatment, cultured neonatal cardiomyocytes showed a diminished Ca2+ transient amplitude associated with an increase in the ß3-AR level. With the addition of a ß3-AR agonist, the Ca2+ transient in LPS-treated neonatal rat cardiomyocytes gradually decreased over time; such a change was absent in cells treated with nitric oxide synthase (NOS) inhibitors prior to treatment with a ß3-AR agonist. In adolescent rats with septic myocardial depression, cardiac function declined as indicated by decreased MAP, dP/dtmax, and dP/dtmix for 6 h after LPS injection; however, the ß3-AR level first increased 2 h after LPS treatment and then decreased 6 h after LPS treatment in the absence of exogenous catecholamines. The results indicate that, in vitro, at the cellular level ß3-AR may be involved in the development of myocardial depression (Ca2+ transient depression) in sepsis through NOS signaling pathways; however, in vivo, a complicated mechanism for modulating ß3-AR may exist.

Structure-Activity Relationships Based on 3D-QSAR CoMFA/CoMSIA and Design of Aryloxypropanol-Amine Agonists with Selectivity for the Human ß3-Adrenergic Receptor and Anti-Obesity and Anti-Diabetic Profiles.

The wide tissue distribution of the adrenergic ß3 receptor makes it a potential target for the treatment of multiple pathologies such as diabetes, obesity, depression, overactive bladder (OAB), and cancer. Currently, there is only one drug on the market, mirabegron, approved for the treatment of OAB. In the present study, we have carried out an extensive structure-activity relationship analysis of a series of 41 aryloxypropanolamine compounds based on three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques. This is the first combined comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) study in a series of selective aryloxypropanolamines displaying anti-diabetes and anti-obesity pharmacological profiles. The best CoMFA and CoMSIA models presented values of r²ncv = 0.993 and 0.984 and values of r²test = 0.865 and 0.918, respectively. The results obtained were subjected to extensive external validation (q², r², r²m, etc.) and a final series of compounds was designed and their biological activity was predicted (best pEC50 = 8.561).

The ß3-adrenergic receptor is dispensable for browning of adipose tissues.

Brown and brite/beige adipocytes are attractive therapeutic targets to treat metabolic diseases. To maximally utilize their functional potential, further understanding is required about their identities and their functional differences. Recent studies with ß3-adrenergic receptor knockout mice reported that brite/beige adipocytes, but not classical brown adipocytes, require the ß3-adrenergic receptor for cold-induced transcriptional activation of thermogenic genes. We aimed to further characterize this requirement of the ß3-adrenergic receptor as a functional distinction between classical brown and brite/beige adipocytes. However, when comparing wild-type and ß3-adrenergic receptor knockout mice, we observed no differences in cold-induced thermogenic gene expression (Ucp1, Pgc1a, Dio2, and Cidea) in brown or white (brite/beige) adipose tissues. Irrespective of the duration of the cold exposure or the sex of the mice, we observed no effect of the absence of the ß3-adrenergic receptor. Experiments with the ß3-adrenergic receptor agonist CL-316,243 verified the functional absence of ß3-adrenergic signaling in these knockout mice. The ß3-adrenergic receptor knockout model in the present study was maintained on a FVB/N background, whereas earlier reports used C57BL/6 and 129Sv mice. Thus our data imply background-dependent differences in adrenergic signaling mechanisms in response to cold exposure. Nonetheless, the present data indicate that the ß3-adrenergic receptor is dispensable for cold-induced transcriptional activation in both classical brown and, as opposed to earlier studies, brite/beige cells.

Combined treatment with a ß3 -adrenergic receptor agonist and a muscarinic receptor antagonist inhibits detrusor overactivity induced by cold stress in spontaneously hypertensive rats.

AIMS: This study determined if combined treatment with the muscarinic receptor (MR) antagonist solifenacin and the ß3 -adrenergic receptor (AR) agonist mirabegron could inhibit detrusor overactivity induced by cold stress in spontaneously hypertensive rats (SHRs). METHODS: Thirty-two female 10-week-old SHRs were fed an 8% NaCl-supplemented diet for 4 weeks. Cystometric measurements of the unanesthetized, unrestricted rats were performed at room temperature (RT, 27 ± 2°C) for 20 min. The rats were then intravenously administered vehicle, 0.1 mg/kg solifenacin alone, 0.1 mg/kg mirabegron alone, or the combination of 0.1 mg/kg mirabegron and 0.1 mg/kg solifenacin (n = 8 each group). Five minutes later, the treated rats were exposed to low temperature (LT, 4 ± 2°C) for 40 min. Finally, the rats were returned to RT. After the cystometric investigations, the ß3 -ARs and M3 -MRs expressed within the urinary bladders were analyzed. RESULTS: Just after transfer from RT to LT, vehicle-, solifenacin-, and mirabegron-treated SHRs exhibited detrusor overactivity that significantly decreased voiding interval and bladder capacity. However, treatment with the combination of solifenacin and mirabegron partially inhibited the cold stress-induced detrusor overactivity patterns. The decreases of voiding interval and bladder capacity in the combination-treated rats were significantly inhibited compared to other groups. Within the urinary bladders, there were no differences between expression levels of M3 -MR and ß3 -AR mRNA. The tissue distribution of M3 -MRs was similar to that of the ß3 -ARs. CONCLUSIONS: This study suggested that the combination of solifenacin and mirabegron act synergistically to inhibit the cold stress-induced detrusor overactivity in SHRs. Neurourol. Urodynam. 36:1026-1033, 2017. © 2016 The Authors. Neurourology and Urodynamics Published by Wiley Periodicals, Inc.

Activation of ß3-adrenoceptors increases in vivo free fatty acid uptake and utilization in brown but not white fat depots in high-fat-fed rats.

Activation of brown adipose tissue (BAT) and browning of white adipose tissue (WAT) present potential new therapies for obesity and type 2 diabetes. Here, we examined the effects of ß3-adrenergic stimulation on tissue-specific uptake and storage of free fatty acids (FFA) and its implications for whole body FFA metabolism in diet-induced obese rats using a multi-radiotracer technique. Male Wistar rats were high fat-fed for 12 wk and administered ß3-agonist CL316,243 (CL, 1 mg·kg-1·day-1) or saline via osmotic minipumps during the last 3 wk. The rats were then fasted and acutely infused with a tracer mixture ([14C]palmitate and the partially metabolized R-[3H]bromopalmitate) under anesthesia. CL infusion decreased body weight gain and fasting plasma glucose levels. While core body temperature was unaffected, infrared thermography showed an increase in tail heat dissipation following CL infusion. Interestingly, CL markedly increased both FFA storage and utilization in interscapular and perirenal BAT, whereas the flux of FFA to skeletal muscle was decreased. In this rat model of obesity, only sporadic populations of beige adipocytes were detected in the epididymal WAT depot of CL-infused rats, and there was no change in FFA uptake or utilization in WAT following CL infusion. In summary, ß3-agonism robustly increased FFA flux to BAT coupled with enhanced utilization. Increased BAT activation most likely drove the increased tail heat dissipation to maintain thermostasis. Our results emphasize the quantitative role of brown fat as the functional target of ß3-agonism in obesity.

Exercise does not activate the ß3 adrenergic receptor-eNOS pathway, but reduces inducible NOS expression to protect the heart of obese diabetic mice.

Obesity and diabetes are associated with higher cardiac vulnerability to ischemia-reperfusion (IR). The cardioprotective effect of regular exercise has been attributed to ß3-adrenergic receptor (ß3AR) stimulation and increased endothelial nitric oxide synthase (eNOS) activation. Here, we evaluated the role of the ß3AR-eNOS pathway and NOS isoforms in exercise-induced cardioprotection of C57Bl6 mice fed with high fat and sucrose diet (HFS) for 12 weeks and subjected or not to exercise training during the last 4 weeks (HFS-Ex). HFS animals were more sensitive to in vivo and ex vivo IR injuries than control (normal diet) and HFS-Ex mice. Cardioprotection in HFS-Ex mice was not associated with increased myocardial eNOS activation and NO metabolites storage, possibly due to the ß3AR-eNOS pathway functional loss in their heart. Indeed, a selective ß3AR agonist (BRL37344) increased eNOS activation and had a protective effect against IR in control, but not in HFS hearts. Moreover, iNOS expression, nitro-oxidative stress (protein s-nitrosylation and nitrotyrosination) and ROS production during early reperfusion were increased in HFS, but not in control mice. Exercise normalized iNOS level and reduced protein s-nitrosylation, nitrotyrosination and ROS production in HFS-Ex hearts during early reperfusion. The iNOS inhibitor 1400 W reduced in vivo infarct size in HFS mice to control levels, supporting the potential role of iNOS normalization in the cardioprotective effects of exercise training in HFS-Ex mice. Although the ß3AR-eNOS pathway is defective in the heart of HFS mice, regular exercise can protect their heart against IR by reducing iNOS expression and nitro-oxidative stress.

Physiological and metabolic functions of the ß3-adrenergic receptor and an approach to therapeutic achievements.

A specific type of beta-adrenergic receptor was discovered in the decade of 1980s and subsequently recognized as a new type of beta-adrenergic receptor, called beta3-adrenoceptor (ß3-AR). ß3-AR expresses in different tissues, including adipose tissue, gall bladder, stomach, small intestine, cardiac myocytes, urinary bladder, and brain. Structurally, ß3-AR is very similar to ß1- and ß2-AR and belongs to a G-protein coupled receptor that uses cAMP as an intracellular second messenger. Alternatively, it also activates the NO-cGMP cascade. Stimulation of the ß3-AR increases lipolysis, fatty acid oxidation, energy expenditure, and insulin action, leading to anti-obesity and anti-diabetic activity. Moreover, ß3-AR differentially regulates the myocardial contraction and relaxes the urinary bladder to balance the cardiac activity and delay the micturition reflex, respectively. In recent years, this receptor has served as an attractive target for the treatment of obesity, type 2 diabetes, congestive heart failure, and overactive bladder syndrome. Several ß3-AR agonists are in the emerging stage that can exert novel pharmacological benefits in different therapeutic areas. The present review focuses on the structure, signaling, physiological, and metabolic activities of ß3-AR. Additionally, therapeutic approaches of ß3-AR have also been considered.

Early postnatal maternal separation causes alterations in the expression of ß3-adrenergic receptor in rat adipose tissue suggesting long-term influence on obesity.

The effects of early postnatal maternal deprivation on the biological characteristics of the adipose tissue later in life were investigated in the present study. Sprague-Dawley rats were classified as either maternal deprivation (MD) or mother-reared control (MRC) groups. MD was achieved by separating the rat pups from their mothers for 3h each day during the 10-15 postnatal days. mRNA levels of mitochondrial uncoupling protein 1 (UCP-1), ß3-adrenergic receptor (ß3-AR), and prohibitin (PHB) in the brown and white adipose tissue were determined using real-time RT-PCR analysis. UCP-1, which is mediated through ß3-AR, is closely involved in the energy metabolism and expenditure. PHB is highly expressed in the proliferating tissues/cells. At 10 weeks of age, the body weight of the MRC and MD rats was similar. However, the levels of the key molecules in the adipose tissue were substantially altered. There was a significant increase in the expression of PHB mRNA in the white adipose tissue, while the ß3-AR mRNA expression decreased significantly, and the UCP-1 mRNA expression remained unchanged in the brown adipose tissue. Given that these molecules influence the mitochondrial metabolism, our study indicates that early postnatal maternal deprivation can influence the fate of adipose tissue proliferation, presumably leading to obesity later in life.