Nebivolol, third-generation β-blocker, may activate β3-adrenergic receptor (AR), which has been emerged as a novel and potential therapeutic targets for cardiovascular diseases. However, it is not known whether nebivolol administration plays a cardioprotective effect against myocardial infarction (MI) injury. Therefore, the present study was designed to clarify the effects of nebivolol on MI injury and to elucidate the underlying mechanism. MI model was constructed by left anterior descending (LAD) artery ligation. Nebivolol, β3-AR antagonist (SR59230A), Nitro-L-arginine methylester (L-NAME) or vehicle was administered for 4 weeks after MI operation. Cardiac function was monitored by echocardiography. Moreover, the fibrosis and the apoptosis of myocardium were assessed by Masson's trichrome stain and TUNEL assay respectively 4 weeks after MI. Nebivolol administration reduced scar area by 68% compared with MI group (p<0.05). Meanwhile, nebivolol also decreased the myocardial apoptosis and improved the heart function after MI (p<0.05 vs. MI). These effects were associated with increased β3-AR expression. Moreover, nebivolol treatment significantly increased the phosphorylation of endothelial NOS (eNOS) and the expression of neuronal NOS (nNOS). Conversely, the cardiac protective effects of nebivolol were abolished by SR and L-NAME. These results indicate that nebivolol protects against MI injury. Furthermore, the cardioprotective effects of nebivolol may be mediated by β3-AR-eNOS/nNOS pathway.

It is unknown whether every ventricular myocyte expresses all 5 of the cardiac adrenergic receptors (ARs), β1, β2, β3, α1A, and α1B. The β1 and β2 are thought to be the dominant myocyte ARs.

Cardiac diseases, such as heart failure, remain leading causes of morbidity and mortality worldwide, with myocardial infarction as the most common etiology. HF is characterized by β-adrenergic receptor (βAR) dysregulation that is primarily due to the upregulation of G protein-coupled receptor kinases that leads to overdesensitization of β1 and β2ARs, and this clinically manifests as a loss of inotropic reserve. Interestingly, the "minor" βAR isoform, the β3AR, found in the heart, lacks G protein-coupled receptor kinases recognition sites, and is not subject to desensitization, and as a consequence of this, in human failing myocardium, the levels of this receptor remain unchanged or are even increased. In different preclinical studies, it has been shown that β3ARs can activate different signaling pathways that can protect the heart. The clinical relevance of this is also supported by the effects of β-blockers which are well known for their proangiogenic and cardioprotective effects, and data are emerging showing that these are mediated, at least in part, by enhancement of β3AR activity. In this regard, targeting of β3ARs could represent a novel potential strategy to improve cardiac metabolism, function, and remodeling.

The mechanisms involved in the development and maintenance of cancer pain remain largely unidentified. Recently, it has been reported that β-adrenergic receptors (β-ARs), mainly β2-and β3-ARs, contribute to tumor proliferation and progression and may favor cancer-associated pain and neuroinflammation. However, the mechanism underlying β-ARs in cancer pain is still unknown. Here, we investigated the role of β1-, β2-and β3-ARs in a mouse model of cancer pain generated by the para-tibial injection of K7M2 osteosarcoma cells. Results showed a rapid tumor growth in the soft tissue associated with the development of mechanical allodynia in the hind paw ipsilateral to the injected site. In addition to reduce tumor growth, both propranolol and SR59230A, β1-/β2-and β3-AR antagonists, respectively, attenuated mechanical allodynia, the number of macrophages and an oxidative stress by-product accumulated in the ipsilateral tibial nerve. The selective β1-AR antagonist atenolol was able to slightly reduce the tumor growth but showed no effect in reducing the development of mechanical allodynia. Results suggest that the development of the mechanical allodynia in K7M2 osteosarcoma-bearing mice is mediated by oxidative stress associated with the recruitment of neural macrophages, and that antagonism of β2-and β3-ARs contribute not solely to the reduction of tumor growth, but also in cancer pain. Thus, the targeting of the β2-and β3-ARs signaling may be a promising therapeutic strategy against both tumor progression and the development of cancer-evoke pain in osteosarcoma.

The abundance of beta 3-adrenergic receptors (β3-ARs) is upregulated in diseased human myocardium. We previously showed that cardiac-specific expression of β3-AR inhibits the hypertrophic response to neurohormonal stimulation. Here, we further analysed signalling pathways involved in the anti-hypertrophic effect of β3-AR.

The hormone adiponectin is secreted by white adipocytes and has been put forward as a key mediator of obesity-linked insulin resistance and the metabolic syndrome. Although adiponectin was discovered two decades ago, the knowledge about the molecular and cellular regulation of its secretion is incomplete. Here we have investigated the adrenergic regulation of adiponectin secretion in primary visceral (gonadal) adipocytes isolated from lean or obese/diabetic mice. We show that visceral adipocyte adiponectin release is triggered by cAMP/catecholamines via signalling pathways involving adrenergic beta-3-receptors (β3ARs) and Exchange Protein directly Activated by cAMP, isoform 1 (Epac1). The adrenergically stimulated adiponectin secretion is blunted in visceral adipocytes isolated from obese and diabetic mice and our results suggest the existence of a secretory defect. We have previously shown that adiponectin secretion in subcutaneous adipocytes is abolished in the obese/diabetic state due to reduced abundance of β3ARs and Epac1. However, here we show that protein levels of β3ARs and Epac1 are maintained in visceral adipocytes from obese/diabetic mice proposing that other molecular defects underlie the blunted adiponectin release. Gene expression analysis indicate diabesity-associated disturbances of the signalling downstream of Epac1 and/or the exocytotic process itself. Our study proposes that visceral adipocytes partake in the regulated secretion of adiponectin and may thus influence circulating levels of the hormone, in health and in metabolic disease.

White adipocyte adiponectin exocytosis is triggered by cAMP and a concomitant increase of cytosolic Ca2+ potentiates its release. White adipose tissue is richly innervated by sympathetic nerves co-releasing noradrenaline (NA) and ATP, which may act on receptors in the adipocyte plasma membrane to increase cAMP via adrenergic receptors and Ca2+ via purinergic receptors. Here we determine the importance of NA and ATP for the regulation of white adipocyte adiponectin exocytosis, at the cellular and molecular level, and we specifically detail the ATP signalling pathway. We demonstrate that tyrosine hydroxylase (enzyme involved in catecholamine synthesis) is dramatically reduced in inguinal white adipose tissue (IWAT) isolated from mice with diet-induced obesity; this is associated with diminished levels of NA in IWAT and with a reduced ratio of high-molecular-weight (HMW) to total adiponectin in serum. Adiponectin exocytosis (measured as an increase in plasma membrane capacitance and as secreted product) is triggered by NA or ATP alone in cultured and primary mouse IWAT adipocytes, and enhanced by a combination of the two secretagogues. The ATP-induced adiponectin exocytosis is largely Ca2+-dependent and activated via purinergic P2Y2 receptors (P2Y2Rs) and the Gq11/PLC pathway. Adiponectin release induced by the nucleotide is abrogated in adipocytes isolated from obese and insulin-resistant mice, and this is associated with ∼70% reduced abundance of P2Y2Rs. The NA-triggered adiponectin exocytosis is likewise abolished in "obese adipocytes", concomitant with a 50% lower gene expression of beta 3 adrenergic receptors (β3ARs). An increase in intracellular Ca2+ is not required for the NA-stimulated adiponectin secretion. Collectively, our data suggest that sympathetic innervation is a principal regulator of adiponectin exocytosis and that disruptions of this control are associated with the obesity-associated reduction of circulating levels of HMW/total adiponectin.

Intracellular calcium-permeable channels have been implicated in thermogenic function of murine brown and brite/beige adipocytes, respectively transient receptor potential melastin-8 and transient receptor potential vanilloid-4. Because the endo-lysosomal two-pore channels (TPCs) have also been ascribed with metabolic functionality, we studied the effect of simultaneously knocking out TPC1 and TPC2 on body composition and energy balance in male mice fed a chow diet. Compared with wild-type mice, TPC1 and TPC2 double knockout (Tpcn1/2(-/-)) animals had a higher respiratory quotient and became obese between 6 and 9 months of age. Although food intake was unaltered, interscapular brown adipose tissue (BAT) maximal temperature and lean-mass adjusted oxygen consumption were lower in Tpcn1/2(-/-) than in wild type mice. Phosphorylated hormone-sensitive lipase expression, lipid density and expression of β-adrenergic receptors were also lower in Tpcn1/2(-/-) BAT, whereas mitochondrial respiratory chain function and uncoupling protein-1 expression remained intact. We conclude that Tpcn1/2(-/-) mice show mature-onset obesity due to reduced lipid availability and use, and a defect in β-adrenergic receptor signaling, leading to impaired thermogenic activity, in BAT.

Brown adipose tissue (BAT) is the site of non-shivering thermogenesis in mammals, wherein energy is dissipated as heat. We observed that aqueous extract of black sesame seed triggers an increase in the expression of Uncoupling Protein 1 (UCP1) in brown adipocytes from mice. The active component from the extract was purified and identified to be sesaminol diglucoside (SDG). SDG treatment decreased mass of white fat pads and serum glucose levels and increased UCP1 levels in BAT thereby protecting mice against high fat induced weight gain. Further in silico and in vitro studies revealed that these effects are due to the agonist like behaviour of SDG towards beta 3 adrenergic receptors (β3-AR). Together, our results suggest that SDG induces BAT mediated thermogenesis through β3-AR and protects mice against diet-induced obesity.

[11C]SNAP-7941 and its radiofluorinated, fluoro-ethyl derivative [18F]FE@SNAP have been developed as the first positron emission tomography tracers for melanin-concentrating hormone receptor 1 (MCHR1) imaging. Accumulation of these MCHR1 PET-tracers in rat brown adipose tissue (BAT) in vivo provided first indication of MCHR1 expression in rodent BAT. To rule out off-target binding, affinity of both MCHR1 ligands toward adrenergic beta-3 receptors (ADRB3) was examined. Further, specific binding of [11C]SNAP-7941 to brown adipocytes and effects of MCHR1 ligands on brown adipocyte activation were investigated. SNAP-7941 and FE@SNAP evinced to be highly selective toward MCHR1. [11C]SNAP-7941 binding to brown adipocytes was shown to be mainly MCHR1-specific. This data strongly indicates MCHR1 expression in rodent BAT and moreover, a peripheral, anti-obesity effect of MCHR1 antagonists directly exerted in BAT is proposed. Moreover, MCHR1 expression in murine brown adipocytes was confirmed by protein and mRNA analysis. We conclude that MCHR1 PET imaging contributes to basic research in endocrinology by elucidating the involvement of the MCH system in peripheral tissues, such as BAT.

The mechanism by which β3 receptor agonists (e.g. mirabegron) control bladder overactivity may involve adenosine release from human and rat detrusor smooth muscle. Retrograde activation of adenosine A1 receptors reduces ACh release from cholinergic bladder nerves. β3 -Adrenoceptors usually couple to adenylyl cyclase. Here we investigated, which of the cAMP targets, protein kinase A or the exchange protein directly activated by cAMP (EPAC) could be involved in this cholinergic inhibition of the bladder.

This study assessed the expression, distribution and function of neurotensin (NTs) and two main neurotensin receptors (NTSR), NTSR1 and NTSR2 in normal rat urinary bladders. NTs is primarily located in the suburothelium and the interstitium of smooth muscle bundles. The NTSR1 and NTSR2 receptor subtypes are found to co-localize with smooth muscle cells (SMCs). NTs not only can directly act on bladder SMCs to induce intracellular calcium mobilization by activating the phospholipase C/inositol triphosphate (PLC/IP3) pathway, promoting extracellular calcium influx through a non-selective cation channels, but may be also involved in the modulation of the cholinergic system. Nowadays, the selective antimuscarinic drugs (solifenacin) and the selective beta 3-adrenergic agonist (mirabegron) are used as the first-line pharmacotherapy for overactive bladder (OAB), but without satisfactory treatment benefits in some patients. This study provided evidence suggesting that bladder NTs may play an important role in the regulation of micturition. Further research is needed to investigate the effects of NTs on bladder contractility and the underlying mechanism, which might reveal that the administration of NTSR antagonists can potentially relieve the symptoms of OAB by coordination with antimuscarinic pharmacotherapy.

In the current work we have investigated the cellular and molecular regulation of resistin secretion in cultured and primary mouse adipocytes. Resistin is an adipose tissue hormone proposed to contribute to metabolic disease. In rodents, resistin is secreted from white adipocytes whereas it is in humans synthesised and released from other cell types within white adipose tissue. The metabolic importance of resistin has been studied in both mouse and man, but the regulation of its release remains poorly investigated. Here we define that, in mouse adipocytes, resistin secretion is triggered by an intracellular elevation of cAMP and/or Ca2+. Resistin release is stimulated via activation of beta 3 adrenergic receptors (β3ARs) and the downstream signalling protein exchange protein activated by cAMP (Epac). The secretion of resistin is markedly abrogated in adipocytes isolated from obese and diabetic mice. Immunocytochemical staining demonstrates a significant overlap between signals for resistin and the adipocyte hormone adiponectin. Our data propose that resistin and adiponectin are contained within the same vesicles in mouse adipocytes and that the two hormones are co-secreted in response to the same exocytosis-triggering signals.

Peroxisome proliferator-activated receptors (PPAR gamma-2) and beta-3-adrenergic receptors (ADRB3) are involved in the risk of hypertension. But their exact role in blood pressure modulation in patients with connective tissue diseases (CTD) is still not well defined. In this study, 104 patients with CTD and 103 gender- and age-matched controls were genotyped for Pro12Ala and C1431T polymorphisms of the PPAR gamma-2 gene and Trp64Arg polymorphism of the ADRB gene. Anthropometric and biochemical measurements were evaluated, followed by genotyping using TaqMan® SNP genotyping assays and polymerase chain reaction-restriction fragment length polymorphism. The prevalence of analyzed genotypes and alleles was comparable between patients with CTD and the control group, as well as hypertensive and normotensive subjects. Patients with CTD have lower body fat and higher body water amount, serum glucose, and triglyceride (TG) levels. Hypertensive subjects are older and have higher body mass, BMI, waist circumference (WC), body water content, glucose, and TG concentration. The multivariate analysis revealed that hypertensive subjects with Ala12/X or Trp64Trp have higher body mass and WC when compared to normotensive subjects. Trp64Trp polymorphism was also characterized by a higher TG level, while T1431/X subjects had higher WC. The presence of CTD, visceral fat distribution, and increased age are the predictors of hypertension development. Hypertensive patients with CTD and Trp64Trp polymorphism have an increased risk of visceral obesity development and metabolic complications, which in turn affects the value of blood pressure. In addition, either Ala12/X or T1431/X predicts the visceral body fat distribution in hypertensive subjects.