Hyaluronan Mediates Cold-Induced Adipose Tissue Beiging.

Adipose tissue beiging refers to the process by which beige adipocytes emerge in classical white adipose tissue depots. Beige adipocytes dissipate chemical energy and secrete adipokines, such as classical brown adipocytes, to improve systemic metabolism, which is beneficial for people with obesity and metabolic diseases. Cold exposure and ß3-adrenergic receptor (AR) agonist treatment are two commonly used stimuli for increasing beige adipocytes in mice; however, their underlying biological processes are different. Transcriptional analysis of inguinal white adipose tissue (iWAT) has revealed that changes in extracellular matrix (ECM) pathway genes are specific to cold exposure. Hyaluronic acid (HA), a non-sulfated linear polysaccharide produced by nearly all cells, is one of the most common components of ECM. We found that cold exposure significantly increased iWAT HA levels, whereas the ß3-AR agonist CL316,243 did not. Increasing HA levels in iWAT by Has2 overexpression significantly increases cold-induced adipose tissue beiging; in contrast, decreasing HA by Spam1 overexpression, which encodes a hyaluronidase that digests HA, significantly decreases cold-induced iWAT beiging. All these data implicate a role of HA in promoting adipose tissue beiging, which is unique to cold exposure. Given the failure of ß3-AR agonists in clinical trials for obesity and metabolic diseases, increasing HA could serve as a new approach for recruiting more beige adipocytes to combat metabolic diseases.

The Role of ß3-Adrenergic Receptors in Cold-Induced Beige Adipocyte Production in Pigs.

After exposure to cold stress, animals enhance the production of beige adipocytes and expedite thermogenesis, leading to improved metabolic health. Although brown adipose tissue in rodents is primarily induced by ß3-adrenergic receptor (ADRB3) stimulation, the activation of major ß-adrenergic receptors (ADRBs) in pigs has been a topic of debate. To address this, we developed overexpression vectors for ADRB1, ADRB2, and ADRB3 and silenced the expression of these receptors to observe their effects on the adipogenic differentiation stages of porcine preadipocytes. Our investigation revealed that cold stress triggers the transformation of subcutaneous white adipose tissue to beige adipose tissue in pigs by modulating adrenergic receptor levels. Meanwhile, we found that ADRB3 promotes the transformation of white adipocytes into beige adipocytes. Notably, ADRB3 enhances the expression of beige adipose tissue marker genes, consequently influencing cellular respiration and metabolism by regulating lipolysis and mitochondrial expression. Therefore, ADRB3 may serve as a pivotal gene in animal husbandry and contribute to the improvement of cold intolerance in piglets.

Adipose tissue rearrangement in cancer cachexia: The involvement of ß3-adrenergic receptor associated pathways.

Cancer-associated cachexia (CAC) is a complex multiple organ syndrome that significantly contributes to reduced quality of life and increased mortality among many cancer patients. Its multifactorial nature makes its early diagnosis and effective therapeutic interventions challenging. Adipose tissue is particularly impacted by cachexia, typically through increased lipolysis, browning and thermogenesis, mainly at the onset of the disease. These processes lead to depletion of fat mass and contribute to the dysfunction of other organs. The ß-adrenergic signalling pathways are classical players in the regulation of adipose tissue metabolism. They are activated upon sympathetic stimulation inducing lipolysis, browning and thermogenesis, therefore contributing to energy expenditure. Despite accumulating evidence suggesting that ß3-adrenergic receptor stimulation may be crucial to the adipose tissue remodelling during cachexia, the literature remains controversial. Moreover, there is limited knowledge regarding sexual dimorphism of adipose tissue in the context of cachexia. This review paper aims to present the current knowledge regarding adipose tissue wasting during CAC, with a specific focus on the role of the ß3-adrenergic receptor, placing it as a potential therapeutic target against cachexia.

ENDOGENOUS ß 3 -ADRENERGIC RECEPTOR ACTIVATION ALLEVIATES SEPSIS-INDUCED CARDIOMYOCYTE APOPTOSIS VIA PI3K/AKT SIGNALING PATHWAY.

ABSTRACT: ß 3 -adrenergic receptor (ß 3 -AR) has been proposed as a new therapy for several myocardial diseases. However, the effect of ß 3 -AR activation on sepsis-induced myocardial apoptosis is unclear. Here, we investigated the effect of ß 3 -AR activation on the cardiomyocyte apoptosis and cardiac dysfunction in cecal ligation and puncture (CLP)-operated rats and lipopolysaccharide (LPS)-treated cardiomyocytes. We found that ß 3 -AR existed both in adult rat ventricular myocytes (ARVMs) and H9c2 cells. The expression of ß 3 -AR was upregulated in LPS-treated ARVMs and the heart of CLP rats. Pretreatment with ß 3 -AR agonist, BRL37344, inhibited LPS-induced cardiomyocyte apoptosis and caspase-3, -8, and -9 activation in ARVMs. BRL37344 also reduced apoptosis and increased the protein levels of PI3K, p-Akt Ser473 and p-eNOS Ser1177 in LPS-treated H9c2 cells. Inhibition of PI3K using LY294002 abolished the inhibitory effect of BRL37344 on LPS-induced caspase-3, -8, and -9 activation in H9c2 cells. Furthermore, administration of ß 3 -AR antagonist, SR59230A (5 mg/kg), significantly decreased the maximum rate of left ventricular pressure rise (+dP/dt) in CLP-induced septic rats. SR59230A not only increased myocardial apoptosis, reduced p-Akt Ser473 and Bcl-2 contents, but also increased mitochondrial Bax, cytoplasm cytochrome c, cleaved caspase-9, and cleaved caspase-3 levels of the myocardium in septic rats. These results suggest that endogenous ß 3 -AR activation alleviates sepsis-induced cardiomyocyte apoptosis via PI3K/Akt signaling pathway and maintains intrinsic myocardial systolic function in sepsis.

Age and sex mediated effects of estrogen and Β3-adrenergic receptor on cardiovascular pathophysiology.

Sex differences are consistently identified in determining the prevalence, manifestation, and response to therapies in several systemic disorders, including those affecting the cardiovascular (CV), skeletal muscle, and nervous system. Interestingly, such differences are often more noticeable as we age. For example, premenopausal women experience a lower risk of CV disease than men of the same age. While at an advanced age, with menopause, the risk of cardiovascular diseases and adverse outcomes increases exponentially in women, exceeding that of men. However, this effect appears to be reversed in diseases such as pulmonary hypertension, where women are up to seven times more likely than men to develop an idiopathic form of the disease with symptoms developing ten years earlier than their male counterparts. Explaining this is a complex question. However, several factors and mechanisms have been identified in recent decades, including a role for sex hormones, particularly estrogens and their related receptors. Furthermore, an emerging role in these sex differences has also been suggested for ß-adrenergic receptors (ßARs), which are essential regulators of mammalian physiology. It has in fact been shown that ßARs interact with estrogen receptors (ER), providing further demonstration of their involvement in determining sexual differences. Based on these premises, this review article focused on the ß3AR subtype, which shows important activities in adipose tissue but with new and interesting roles in regulating the function of cardiomyocytes and vascular cells. In detail, we examined how ß3AR and ER signaling are intertwined and whether there would be sex- and age-dependent specific effects of these receptor systems.

Genetic evidence for involvement of ß2-adrenergic receptor in brown adipose tissue thermogenesis in humans.

BACKGROUND: Sympathetic activation of brown adipose tissue (BAT) thermogenesis can ameliorate obesity and related metabolic abnormalities. However, crucial subtypes of the ß-adrenergic receptor (AR), as well as effects of its genetic variants on functions of BAT, remains unclear in humans. We conducted association analyses of genes encoding ß-ARs and BAT activity in human adults. METHODS: Single nucleotide polymorphisms (SNPs) in ß1-, ß2-, and ß3-AR genes (ADRB1, ADRB2, and ADRB3) were tested for the association with BAT activity under mild cold exposure (19 °C, 2 h) in 399 healthy Japanese adults. BAT activity was measured using fluorodeoxyglucose-positron emission tomography and computed tomography (FDG-PET/CT). To validate the results, we assessed the effects of SNPs in the two independent populations comprising 277 healthy East Asian adults using near-infrared time-resolved spectroscopy (NIRTRS) or infrared thermography (IRT). Effects of SNPs on physiological responses to intensive cold exposure were tested in 42 healthy Japanese adult males using an artificial climate chamber. RESULTS: We found a significant association between a functional SNP (rs1042718) in ADRB2 and BAT activity assessed with FDG-PET/CT (p < 0.001). This SNP also showed an association with cold-induced thermogenesis in the population subset. Furthermore, the association was replicated in the two other independent populations; BAT activity was evaluated by NIRTRS or IRT (p < 0.05). This SNP did not show associations with oxygen consumption and cold-induced thermogenesis under intensive cold exposure, suggesting the irrelevance of shivering thermogenesis. The SNPs of ADRB1 and ADRB3 were not associated with these BAT-related traits. CONCLUSIONS: The present study supports the importance of ß2-AR in the sympathetic regulation of BAT thermogenesis in humans. The present collection of DNA samples is the largest to which information on the donor's BAT activity has been assigned and can serve as a reference for further in-depth understanding of human BAT function.

Inside the Biology of the ß3-Adrenoceptor.

Since the first discovery in 1989, the ß3-adrenoceptor (ß3-AR) has gained great attention because it showed the ability to regulate many physiologic and metabolic activities, such as thermogenesis and lipolysis in brown and white adipose tissue, respectively (BAT, WAT), negative inotropic effects in cardiomyocytes, and relaxation of the blood vessels and the urinary bladder. The ß3-AR has been suggested as a potential target for cancer treatment, both in adult and pediatric tumors, since under hypoxia its upregulation in the tumor microenvironment (TME) regulates stromal cell differentiation, tumor growth and metastases, signifying that its agonism/antagonism could be useful for clinical benefits. Promising results in cancer research have proposed the ß3-AR being targeted for the treatment of many conditions, with some drugs, at present, undergoing phase II and III clinical trials. In this review, we report the scientific journey followed by the research from the ß3-Ars' discovery, with focus on the ß3-Ars' role in cancer initiation and progression that elects it an intriguing target for novel antineoplastic approaches. The overview highlights the great potential of the ß3-AR, both in physiologic and pathologic conditions, with the intention to display the possible benefits of ß3-AR modulation in cancer reality.

Genomic and transcriptomic analysis of breast cancer identifies novel signatures associated with response to neoadjuvant chemotherapy.

BACKGROUND: Neoadjuvant chemotherapy (NAC) has become a standard treatment strategy for breast cancer (BC). However, owing to the high heterogeneity of these tumors, it is unclear which patient population most likely benefit from NAC. Multi-omics offer an improved approach to uncovering genomic and transcriptomic changes before and after NAC in BC and to identifying molecular features associated with NAC sensitivity. METHODS: We performed whole-exome and RNA sequencing on 233 samples (including matched pre- and post-treatment tumors) from 50 BC patients with rigorously defined responses to NAC and analyzed changes in the multi-omics landscape. Molecular features associated with NAC response were identified and validated in a larger internal, and two external validation cohorts, as well as in vitro experiments. RESULTS: The most frequently altered genes were TP53, TTN, and MUC16 in both pre- and post-treatment tumors. In comparison with pre-treatment tumors, there was a significant decrease in C > A transversion mutations in post-treatment tumors (P = 0.020). NAC significantly decreased the mutation rate (P = 0.006) of the DNA repair pathway and gene expression levels (FDR = 0.007) in this pathway. NAC also significantly changed the expression level of immune checkpoint genes and the abundance of tumor-infiltrating immune and stroma cells, including B cells, activated dendritic cells, γδT cells, M2 macrophages and endothelial cells. Furthermore, there was a higher rate of C > T substitutions in NAC nonresponsive tumors than responsive ones, especially when the substitution site was flanked by C and G. Importantly, there was a unique amplified region at 8p11.23 (containing ADGRA2 and ADRB3) and a deleted region at 3p13 (harboring FOXP1) in NAC nonresponsive and responsive tumors, respectively. Particularly, the CDKAL1 missense variant P409L (p.Pro409Leu, c.1226C > T) decreased BC cell sensitivity to docetaxel, and ADGRA2 or ADRB3 gene amplifications were associated with worse NAC response and poor prognosis in BC patients. CONCLUSIONS: Our study has revealed genomic and transcriptomic landscape changes following NAC in BC, and identified novel biomarkers (CDKAL1P409L, ADGRA2 and ADRB3) underlying chemotherapy resistance and poor prognosis, which could guide the development of personalized treatments for BC.

Blocking brown adipocyte ß3-adrenoceptor attenuates blood-spinal cord barrier impairment and chronic postsurgical pain in a rat model of preoperative stress.

Preoperative stress has been recognized as an independent risk factor for chronic postsurgical pain (CPSP). However, the underlying mechanisms of CPSP influenced by preoperative stress remain elusive. Previous studies indicated that excessive stress could induce disruption of the blood-spinal cord barrier (BSCB). We wondered whether and how BSCB involves in CPSP by using a single prolonged stress (SPS) combining plantar incision model in male rats to mimic preoperative stress-related postsurgical pain. Here, we observed that preoperative SPS-exposed rats exhibited relentless incisional pain, which was accompanied by impairment of BSCB and persistent elevation of serum IL-6. Intraperitoneal injections of Tocilizumab (an IL-6 receptor monoclonal antibody) not only mitigated BSCB breakdown but also alleviated pain behaviors. In addition, intervening ß3-adrenoceptor (ADRB3) signaling in brown adipocytes by SR59230a (a specific ADRB3 antagonist) treatment or removal of brown adipose tissues could effectively decrease serum IL-6 levels, ameliorate BSCB disruption, and alleviate incisional pain. Further results displayed that SI-exposed rats also showed markedly spinal microglia activation. And exogenous His-tagged IL-6 could pass through the disrupted BSCB, which might contribute to microglia activation. Injection of SR59230a or ablation of brown adipose tissues could effectively reduce the activation of spinal microglia. Thus, our findings suggest that serum IL-6 induced by brown adipocyte ADRB3 signaling contributed to BSCB disruption and spinal microglia activation, which might be involved in preoperative stress mediated CPSP. This work indicates a promising treatment strategy for preoperative stress induced CPSP by blocking ADRB3.

ß-Adrenoceptors regulate urothelial inflammation and zonula occludens in the bladder outlet obstruction model.

BACKGROUND: The purpose of this study was to evaluate the effects of ß-adrenoceptors (ADRBs) on the urothelial inflammation and zonula occludens (ZO) in a rat PBOO model and in an in vitro model. METHODS: The PBOO model was established by ligating the bladder neck of rats. Twenty rats were divided into 4 groups: sham operation, PBOO + normal saline, PBOO + ADRB2 agonist, PBOO + ADRB3 agonist. PBOO rats were with treated with ADRBs agonists for 3 weeks. Human urothelial cells (HUCs) were subjected to ADRBs agonist treatment or hydrostatic pressure in an in vitro model. RESULTS: In the PBOO group, there was a significant increase in the expression of MCP-1, IL-6 and RANTES compared to the sham group. By contrast, there was a post-PBOO decline in the expression of ZO-1 and ZO-2 in the urothelium. ADRB2 or ADRB3 agonists exhibited downregulated inflammatory cytokine expression and increased ZO expression in the PBOO model. The regulation of inflammation and ZO by ADRB2 and ADRB3 agonists in an in vitro model was found consistent with that in the PBOO model. Moreover, RhoA and ROCK inhibitors suppressed the expression of hydrostatic pressure-induced inflammatory cytokines. Additionally, RhoA agonist reversed the inhibitory effect of ADRBs agonists on the inflammatory secretion from HUCs. CONCLUSIONS: ADRB2 and ADRB3 agonists increased ZO protein expression in HUCs in a rat PBOO model and in an in vitro model. Furthermore, ADRB2 and ADRB3 agonists inhibited the secretion of inflammatory cytokines from HUCs by regulating the RhoA/ROCK signaling pathways.

Is the ß3-Adrenoceptor a Valid Target for the Treatment of Obesity and/or Type 2 Diabetes?

ß3-Adrenoceptors mediate several functions in rodents that could be beneficial for the treatment of obesity and type 2 diabetes. This includes promotion of insulin release from the pancreas, cellular glucose uptake, lipolysis, and thermogenesis in brown adipose tissue. In combination, they lead to a reduction of body weight in several rodent models including ob/ob mice and Zucker diabetic fatty rats. These findings stimulated drug development programs in various pharmaceutical companies, and at least nine ß3-adrenoceptor agonists have been tested in clinical trials. However, all of these projects were discontinued due to the lack of clinically relevant changes in body weight. Following a concise historical account of discoveries leading to such drug development programs we discuss species differences that explain why ß3-adrenoceptors are not a meaningful drug target for the treatment of obesity and type 2 diabetes in humans.

ß3 Adrenoceptor Agonism Prevents Hyperoxia-Induced Colonic Alterations.

Oxygen level is a key regulator of organogenesis and its modification in postnatal life alters the maturation process of organs, including the intestine, which do not completely develop in utero. The ß3-adrenoreceptor (ß3-AR) is expressed in the colon and has an oxygen-dependent regulatory mechanism. This study shows the effects of the ß3-AR agonist BRL37344 in a neonatal model of hyperoxia-driven colonic injury. For the first 14 days after birth, Sprague-Dawley rat pups were exposed to ambient oxygen levels (21%) or hyperoxia (85%) and treated daily with BRL37344 at 1, 3, 6 mg/kg or untreated. At the end of day 14, proximal colon samples were collected for analysis. Hyperoxia deeply influences the proximal colon development by reducing ß3-AR-expressing cells (27%), colonic length (26%) and mucin production (47%), and altering the neuronal chemical coding in the myenteric plexus without changes in the neuron number. The administration of BRL37344 at 3 mg/kg, but not at 1 mg/kg, significantly prevented these alterations. Conversely, it was ineffective in preventing hyperoxia-induced body weight loss. BRL37344 at 6 mg/kg was toxic. These findings pave the way for ß3-AR pharmacological targeting as a therapeutic option for diseases caused by hyperoxia-impaired development, typical prematurity disorders.

Diseño y validación de un ensayo de minisecuenciación múltiple para detectar polimorfismos asociados con Síndrome Metabólico / Design and validation of a multiple minisequencing assay to detect polymorphisms associated with Metabolic Syndrome

Resumen Introducción: Es importante identificar los polimorfismos de interés clínico en patologías complejas como el Síndrome Metabólico. Por esto, las metodologías para su evaluación deben estar diseñadas y validadas correctamente, esto permite optimizar recursos y tiempo en la genotipificación y detección correcta de los alelos presentes en los individuos. Objetivo: Diseñar y validar una PCR múltiple, seguida de detección por minisecuenciación, para la genotipificación de ocho polimorfismos de nucleótido simple ubicados en el gen del Receptor Beta 3-Adrenérgico (rs4994 y rs4998), gen de la Apolipoproteina A5 (rs3135506 y rs2075291), gen de la Adiponectina (rs1501299 y rs2241766) y gen del Receptor Activador de la Proliferación de los Peroxisomas tipo gamma (rs1801282 y rs1800571), asociados con el síndrome metabólico. Materiales y métodos: Se diseñaron 24 cebadores para la amplificación y detección de ocho polimorfismos de nucleótido sencillo ubicados en cuatro genes candidatos a estar asociados con el síndrome metabólico, usando el software Primer3®. Dieciséis fueron diseñados para amplificar los polimorfismos y ocho para detectarlos por minisecuenciación. Las estructuras secundarias entre los cebadores se verificaron con el software Autodimer. Los polimorfismos se amplificaron simultáneamente y los fragmentos amplificados se acoplaron a las sondas diseñadas para detectar por minisecuenciación el alelo presente, por medio de bases marcadas con fluorocromos. Finalmente, los alelos fueron detectados por electroforesis capilar en un analizador genético ABI 310 y se interpretaron con el software GeneMapper®. La validación del multiplex se realizó genotipando 20 muestras de individuos, cada uno de ellos autorizó este procedimiento por medio del consentimiento informado. Resultados: Se obtuvieron los perfiles genéticos de los 20 controles genotipados, a partir de la amplificación múltiple, seguida de minisecuenciación, diseñada y validada para detectar los ocho polimorfismos. Conclusión: Se diseñó y validó un ensayo para la detección simultánea de los polimorfismos, ubicados en cuatro genes asociados con el Síndrome metabólico. Los cuales pueden ser empleados como referencia para futuros estudios poblacionales.

Abstract Introduction: It is important to identify the polymorphisms of clinical interest in complex pathologies such as Metabolic Syndrome. Therefore, the methodologies for its evaluation must be designed and validated correctly, this permits optimization of resources and time in genotyping and correct detection of the alleles present in individuals. Objective: To design and validate a multiplex PCR, followed by detection by minisequencing, for the genotyping of eight single nucleotide polymorphisms located in the Beta 3-Adrenergic Receptor gene (rs4994 and rs4998), Apolipoprotein A5 gene (rs3135506 and rs2075291), Adiponectin gene (rs1501299 and rs2241766) and gamma-type Peroxisome Proliferation Activating Receptor gene (rs1801282 and rs1800571), associated with metabolic syndrome. Materials and methods: Twenty-four primers were designed for the amplification and detection of eight single nucleotide polymorphisms located in four candidate genes to be associated with the metabolic syndrome, using the Primer3® software. Sixteen were designed to amplify the polymorphisms and eight to detect them by minisequencing. The secondary structures between the primers were verified with Autodimer software. The polymorphisms were simultaneously amplified, and the amplified fragments were coupled to probes designed to minisequence the present allele using fluorochrome-labeled bases. Finally, the alleles were detected by capillary electrophoresis using an ABI 310 genetic analyzer and analyzed with the GeneMapper® software. The validation of the multiplex was performed by genotyping 20 individual samples, each of them authorized this procedure through informed consent. Results: The genetic profiles of the 20 genotyped controls were obtained, from multiple amplification, followed by minisequencing, designed and validated to detect the eight polymorphisms. Conclusion: An essay was designed and validated for the simultaneous detection of polymorphisms, located in four genes associated with metabolic syndrome, and can used as a reference for future population studies.

Methylation profile of the ADRB3 gene and its association with lipid profile and nutritional status in adults

BACKGROUND: Defects in DNA methylation have been shown to be associated with metabolic diseases such as obesity, dyslipidemia, and hypercholesterolemia. To analyze the methylation profile of the ADRB3 gene and correlate it with lipid profile, lipid intake, and oxidative stress based on malondialdehyde (MDA) and total antioxidant capacity (TAC), homocysteine and folic acid levels, nutritional status, lifestyle, and socioeconomic variables in an adult population. A cross-sectional epidemiological study representative of the East and West regions of the municipality of João Pessoa, Paraíba state, Brazil, enrolled 265 adults of both genders. Demographic, lifestyle, and socioeconomic questionnaires and a 24-h recall questionnaire were applied by trained interviewers' home. Nutritional and biochemical evaluation (DNA methylation, lipid profile, MDA, TAC, homocysteine and folic acid levels) was performed. RESULTS: DNA hypermethylation of the ADRB3 gene, analyzed in leukocytes, was present in 50% of subjects and was associated with a higher risk of being overweight (OR 3.28; p = 0.008) or obese (OR 3.06; p = 0.017), a higher waist-hip ratio in males (OR 1.17; p = 0.000), greater intake of trans fats (OR 1.94; p = 0.032), higher LDL (OR 2.64; p = 0.003) and triglycerides (OR 1.81; p = 0.031), and higher folic acid levels (OR 1.85; p = 0.022). CONCLUSIONS: These results suggest that epigenetic changes in the ADRB3 gene locus may explain the development of obesity and non-communicable diseases associated with trans-fat intake, altered lipid profile, and elevated folic acid. Because of its persistence, DNA methylation may have an impact in adults, in association with the development of non-communicable diseases. This study is the first population-based study of the ADRB3 gene, and the data further support evaluation of ADRB3 DNA methylation as an effective biomarker.

Trp64Arg polymorphism of the ADRB3 gene associated with maximal fat oxidation and LDL-C levels in non-obese adolescents / Polimorfismo Trp64Arg do gene ADRB3 associado à oxidação máxima de gorduras e à concentração de LDL-c em adolescentes não obesos

Abstract Objective: To analyze the association between the Trp64Arg polymorphism of the ADRB3 gene, maximal fat oxidation rates and the lipid profile levels in non-obese adolescents. Methods: 72 schoolchildren, of both genders, aged between 11 and 17 years, participated in the study. The anthropometric and body composition variables, in addition to total cholesterol, HDL-c, LDL-c, triglycerides, insulin, and basal glycemia, were evaluated. The sample was divided into two groups according to the presence or absence of the polymorphism: non-carriers of the Arg64 allele, i.e., homozygous (Trp64Trp: n = 54), and carriers of the Arg64 allele (Trp64Arg + Arg64Arg: n = 18), in which the frequency of the Arg64 allele was 15.2%. The maximal oxygen uptake and peak of oxygen uptake during exercise were obtained through the symptom-limited, submaximal treadmill test. Maximal fat oxidation was determined according to the ventilatory ratio proposed in Lusk's table. Results: Adolescents carrying the less frequent allele (Trp64Arg and Arg64Arg) had higher LDL-c levels (p = 0.031) and lower maximal fat oxidation rates (p = 0.038) when compared with non-carriers (Trp64Trp). Conclusions: Although the physiological processes related to lipolysis and lipid metabolism are complex, the presence of the Arg 64 allele was associated with lower rates of FATMAX during aerobic exercise, as well as with higher levels of LDL-c in adolescents.

Resumo Objetivo: Analisar a associação entre o polimorfismo Trp64Arg do gene ADRB3, as taxas de oxidação máxima de gorduras e as concentrações do perfil lipídico em adolescentes não obesos. Métodos: Participaram do estudo 72 escolares, de ambos os sexos, com idade entre 11 e 17 anos. Foram avaliadas as variáveis antropométricas e de composição corporal, além do colesterol total, lipoproteina de alta densidade, lipoproteina de baixa densidade, triglicerídeos; insulina e glicemia basal. A amostra foi dividida em dois grupos, segundo a presença ou não do polimorfismo: não portadores do alelo Arg64, ou seja, homozigotos (Trp64Trp: n = 54) e portadores do alelo Arg64 (Trp64Arg + Arg64Arg: n = 18), em que a frequência do alelo Arg64 foide 15,2%. O consumo máximo de oxigênio e pico de consumo máximo de oxigênio durante o exercício foram obtidos por meio do teste aeróbio submáximo de sintoma limitado em esteira. A oxidação máxima de gorduras foi determinada de acordo com a razão de trocas ventilatórias propostas na Tabela de Lusk. Resultados: Os adolescentes portadores do alelo menos frequente (Trp64Arg e Arg64Arg) apresentaram maiores concentrações de lipoproteina de baixa densidade (p = 0,031) e menores taxasde oxidação máxima de gorduras (p = 0,038) quando comparados aos não portadores (Trp64Trp). Conclusões: Embora os processos fisiológicos relacionados à lipólise e ao metabolismo de lipídeos sejam complexos, a presença do alelo Arg64 associou-se a menores taxas de FATMAX durante exercício aeróbio, bem como maiores níveis de lipoproteina de baixa densidade em adolescentes.

Adrenergic receptor ß3 is involved in the memory consolidation process in mice

Attention and emotion have a positive impact on memory formation, which is related to the activation of the noradrenergic system in the brain. The hippocampus and amygdala are fundamental structures in memory acquisition, which is modulated by noradrenaline through the noradrenergic receptors. Pharmacological studies suggest that memory acquisition depends on the action of both the β3 (β3-AR) and β2 (β2-AR) receptor subtypes. However, the use of animal models with specific knockout for the β3-AR receptor only (β3-ARKO) allows researchers to more accurately assess its role in memory formation processes. In the present study, we evaluated short- and long-term memory acquisition capacity in β3-ARKO mice and wild-type mice at approximately 60 days of age. The animals were submitted to the open field test, the elevated plus maze, object recognition, and social preference. The results showed that the absence of the β3-AR receptor caused no impairment in locomotion and did not cause anxious behavior, but it caused significant impairment of short- and long-term memory compared to wild-type animals. We also evaluated the expression of genes involved in memory consolidation. The mRNA levels for GLUT3, a glucose transporter expressed in the central nervous system, were significantly reduced in the amygdala, but not in the hippocampus of the β3-ARKO animals. Our results showed that β3-AR was involved in the process of acquisition of declarative memory, and its action may be due to the facilitation of glucose absorption in the amygdala.

Effects 'of β3 adrenoceptors on the contractility of rat thoracic aorta smooth muscle and the mechanism / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To observe the effect of β₃adrenoceptors (β₃-AR) activation on rat thoracic aorta smooth muscle contractility and the possible related mechanism.</p><p><b>METHODS</b>The endothelium removed thoracic aorta was pre-contracted with 30 mmol/L KCl physiological saline solution (PSS). Then the tension of the thoracic aorta was recorded in presence of BRL37344 (BRL) to determine the action of β₃-AR. The tension of the thoracic aorta was also recorded in the presence of Propranolol (PRA), SR59230A (SR), L-NNA, H-89 and Iberiotoxin (IBTX) respectively to reveal the underling mechanism of β₃-AR activation on rat vascular smooth muscle. Immunohistochemistry was adopted to confirm the existence and the distribution of β₃-AR in rat thoracic aorta.</p><p><b>RESULTS</b>The results showed that: (1) The thoracic aorta was relaxed by β₃-AR activation, with a relaxation percentage of (10.59 ± 0.79). (2) β₃-AR was expressed in both endothelial and smooth muscle layer in thoracic aorta sections of rats. (3) PRA did not block the effect of BRL on the thoracic aorta. The relaxation actions of BRL could be antagonized by pre-incubating the thoracic aorta with SR. (4) L-NNA (a NOS inhibitor) and H-89 (a PKA inhibitor) reversed the relaxation effect of BRL on vascular smooth muscle. (5) The effect of BRL was decreased after application of Ibriotoxin (IBTX), a large conductance calcium dependent potassium channel blocker.</p><p><b>CONCLUSION</b>The results confirmed that activation of β₃-AR led to relaxation of thoracic aorta smooth muscle. The relaxation action of β₃-AR on smooth muscle of rat thoracic aorta was related to activation of NOS and PKA signaling pathway. Large conductance Ca²⁺-K⁺ channels were involved in the relaxation action of β₃-AR activation on rat thoracic aorta smooth muscle.</p>

β3-adrenoceptor impacts apoptosis in cultured cardiomyocytes via activation of PI3K/Akt and p38MAPK / 华中科技大学学报（医学）（英德文版）

β3-adrenoceptor (β3-AR) has been shown to promote myocardial apoptosis. However, the exact physiological role and importance of this receptor in the human myocardium, and its underlying mode of action, have not been fully elucidated. The present study aimed to determine the effects of β3-AR on the promotion of myocardial apoptosis and on norepinephrine (NE) injury. We analyzed NE-induced cardiomyocyte (CM) apoptosis by using a TUNEL and an annexin V/propidium iodide apoptosis assay. Furthermore, we investigated the NE-induced expression of the apoptosis marker genes Akt and p38MAPK, their phosphorylated counterparts p-Akt and p-p38MAPK, caspase-3, Bcl-2, and Bax. In addition, we determined the effect of a 48-h treatment with a β3-AR agonist and antagonist on expression of these marker genes. β3-AR overexpression was found to increase CM apoptosis, accompanied by an increased expression of caspase-3, bax/bcl-2, and p-p38MAPK. In contrast, the β3-blocker reduced apoptosis of CMs and the associated elevated Akt expression. We identified a novel and potent anti-apoptosis mechanism via the PI3K/Akt pathway and a pro-apoptosis pathway mediated by p38MAPK.

Distribution of β3-adrenergic receptors gene polymorphisms and its association with serum lipid in Han and Uighur populations in Xinjiang / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the distribution of β3-adrenergic receptors (ADRβ3) gene polymorphisms (rs2298423 and rs6986132) and its association with serum lipid in Han and Uighur populations in Xinjiang.</p><p><b>METHODS</b>Genotypes of the ADR β 3 gene were detected in 362 Uighur and 653 Han healthy individuals who were randomly selected in Xinjiang by real-time PCR (TaqMan) method.</p><p><b>RESULTS</b>1) Frequencies of TT, GT and GG genotypes of the rs2298423 locus were 76.5%, 22.1% and 1.4% in the Uighurs but 74.7%, 23.3% and 2.0% in the Hans. There was no significant difference noticed in distribution of genotypes between the two populations (P = 0.695). 2) Frequencies of GG, AG and AA genotypes of the rs6986132 locus were 81.5%, 16.6% and 1.9% in Uighurs but 59.6%, 33.7% and 6.7% in Hans. There was significant difference noticed in the distribution of genotypes between the two populations (P < 0.001). 3) Total cholesterol and low density lipoprotein cholesterol levels were significantly higher in GG or GT genotypes than in the TT genotype carriers of rs2298423 in the Uighur individuals (P < 0.01), but not in the Han population. Serum lipid level that including total cholesterol (TC), low density lipoproteins cholesterol (LDL-C), triglyceride and high density lipoproteins cholesterol did not show significant differences in the distribution of rs6986132 genotypes between the two populations (P > 0.05). After adjusting for factors as gender, age, height, weight, waist circumference, blood urea nitrogen, creatin, glucose, triglyceride, smoking, drinking, results from the logistic regression analyses revealed that those individuals who were carrying GG or GT genotype of rs2298423 were expected to face an increased risk for total cholesterol and low density lipoprotein cholesterol level than those individuals that carrying TT genotype in Uighur populations (OR = 3.140, 95% CI: 1.270-7.764, P = 0.013 in TC level; OR = 3.818, 95% CI: 1.761-8.280, P = 0.001 in LDL-C level). 4) The T-G haplotype appeared more frequent in the Uighurs while the T-A haplotype was more commonly seen in the Han population, respectively (both P < 0.001).</p><p><b>CONCLUSION</b>The mutational frequencies of the tagging SNPs in rs2298423 and rs6986132 loci of the ADRβ 3 gene presented obvious differences between Han and Uighur populations of Xinjiang. G allele carriers of rs2298423 seemed to face an increased risk for TC and LDL-C level in the Uighur populations in Xinjiang.</p>

Association of T190C polymorphism of β3 adrenergic receptor gene with response to carvedilol in patients with chronic heart failure / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the association of T190C polymorphism of β3 adrenergic receptor gene (β3-AR) with chronic heart failure (CHF), and to evaluate the effect of this polymorphism on clinical response to β-AR blockade among patients with CHF.</p><p><b>METHODS</b>Three hundred and thirty patients with stable CHF receiving basic therapy for heart failure were included. Before initiation and 5 months after the maximal tolerated dose of carvedilol was reached, all indices including heart rate (HR), blood pressure (BP), left atrial diameter (LAD), left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left ventricular ejection fraction (LVEF), brain natriuretic peptide (BNP) level, 6 min walk distance were measured and compared with the indices of those with a T190C genotype. Distribution of the T190C polymorphisms in the control group and CHF group was compared.</p><p><b>RESULTS</b>The frequencies of T190C genotypes of the β3-AR gene have fit with the Hardy-Weinberg equilibrium. No significant difference was found between the frequencies of T190C alleles and genotypes between the two groups (P > 0.05). Compared with CC-homozygotes, TT-homozygous patients showed substantially greater improvement in LVEF and BNP (all P < 0.01).</p><p><b>CONCLUSION</b>No difference has been detected in the prevalence of the three genotypes between healthy and CHF subjects. The T190C variation of the β3-AR gene was not associated with increased risk for CHF. CHF patients with a T allele have greater response to carvedilol than those carrying a C allele in ethnic Han Chinese.</p>