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.
Adrenergic Agonists ; pharmacology ; Adrenergic Antagonists ; pharmacology ; Animals ; Apoptosis ; Cells, Cultured ; Myocytes, Cardiac ; drug effects ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, beta-3 ; genetics ; metabolism ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo observe the effect of β₃adrenoceptors (β₃-AR) activation on rat thoracic aorta smooth muscle contractility and the possible related mechanism.

METHODSThe 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.

RESULTSThe 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.

CONCLUSIONThe 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.

Animals ; Aorta, Thoracic ; physiology ; In Vitro Techniques ; Isoquinolines ; Large-Conductance Calcium-Activated Potassium Channels ; physiology ; Muscle Contraction ; Muscle Relaxation ; Muscle, Smooth, Vascular ; physiology ; Nitroarginine ; Peptides ; Propanolamines ; Propranolol ; Rats ; Receptors, Adrenergic, beta-3 ; physiology ; Signal Transduction ; Sulfonamides

OBJECTIVETo 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.

METHODSThree 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.

RESULTSThe frequencies of T190C genotypes of the &beta;3-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).

CONCLUSIONNo difference has been detected in the prevalence of the three genotypes between healthy and CHF subjects. The T190C variation of the &beta;3-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.

Adult ; Carbazoles ; therapeutic use ; Chronic Disease ; Female ; Heart Failure ; drug therapy ; genetics ; physiopathology ; Humans ; Male ; Middle Aged ; Polymorphism, Genetic ; Propanolamines ; therapeutic use ; Receptors, Adrenergic, beta-3 ; genetics ; Ventricular Function, Left

OBJECTIVETo observe the effects of beta3-adrenergic receptor(beta3-AR) antagonist on myocardial uncoupling protein 2 (UCP2) expression and energy metabolism in chronic heart failure rats.

METHODSSeven weight-matched normal adult rats (control group), 18 isoproterenol (ISO) induced heat failure (HR) rats (ISO group) and 21 ISO induced heart failure rats but received specific beta3-AR inhibitor SR59230A (ISO+ SR59230A group) for 6 weeks were included in this research. At the end of the study, echocardiography was performed, the ratio of left ventricular weight and body weight (LVW/BW) was calculated. The expression of beta3-AR ad UCP2 mRNA in myocardium were detected by reverse transcription-polymerase chain reaction (RT-PCR), the UCP2 protein in myocardium were detected by Western blot. The myocardial contents of creatine phosphate (PCr) and adenosine triphosphate (ATP) were measured by high performance liquid chromatography (HPLC).

RESULTSCompared with control group, the cardiac function was significantly reduced and myocardial beta3-AR mRNA significantly increased, UCP2 mRNA and protein were also significantly increased in ISO group, this change could be attenuated by the treatment with SR59230A, and the expression of myocardial UCP2 protein negatively correlated with the ratio of PCr/ATP.

CONCLUSIONIn the chronic stage of HF, the expression of UCP2 increases, which causes myocardial energy shortage, SR59230A improves myocardia energy efficiency and cardiac function by means of suppressing the expression of UCP2.

Adrenergic Antagonists ; pharmacology ; Animals ; Energy Metabolism ; Heart Failure ; metabolism ; Ion Channels ; metabolism ; Male ; Mitochondrial Proteins ; metabolism ; Myocardium ; metabolism ; Rats ; Rats, Wistar ; Receptors, Adrenergic, beta-3 ; metabolism ; Uncoupling Protein 2

OBJECTIVETo investigate the antiobesity effect of Jueming Prescription (JMP), a Chinese herbal medicine formula, and its influence on mRNA expressions of beta3 adrenergic receptor (beta3-AR) and uncoupling protein-2 (UCP-2) in adipose tissue of diet-induced obese rats.

METHODSFifty male Sprague-Dawley rats were randomly divided into the normal control group (n =8) that was on a standard chow diet, and the obese model group (n =42) that was on a diet of high fat chow. Two weeks after the high fat diet, 29 obese rats in the obese model group were further randomly divided into 3 groups: the untreated obese model group (n =9), the metformin group (n =10, metformin 300 mg kg⁻¹ day)⁻¹, and the JMP group (n =10, JMP 4 g kg⁻¹ day⁻¹). After 8-week treatment, body weight, wet weight of visceral fat, and percentage of body fat (PBF) were measured. The levels of fasting blood glucose, serum lipids, and insulin were assessed, and insulin sensitivity index (ISI) was calculated. The adipose tissue section was stained with hematoxylin-Eosin, and the cellular diameter and quantity of adipocytes were evaluated by light microscopy. The mRNA expressions of beta3-AR and UCP-2 from the peri-renal fat tissue were determined by real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTSCompared with the obese model group, treatment with JMP resulted in significantly lower body weight, wet weight of visceral fat, PBF, and diameter of adipocytes, and significantly higher level of high-density lipoprotein cholesterol, ISI (all P<0.01), JMP increased the mRNA expressions of beta3-AR and UCP-2 from perirenal fat tissue (P <0.05, P<0.01).

CONCLUSIONSJMP could reduce body weight and adipocyte size; and the effect was associated with the up-regulation of beta3-AR and UCP-2 expressions in the adipose tissue and improvement of insulin sensitivity.

Adipocytes ; drug effects ; metabolism ; pathology ; Adiposity ; drug effects ; Animals ; Blood Glucose ; metabolism ; Body Weight ; drug effects ; Cell Size ; drug effects ; Diet, High-Fat ; Drugs, Chinese Herbal ; pharmacology ; Epididymis ; drug effects ; pathology ; Fasting ; blood ; Gene Expression Regulation ; drug effects ; Insulin ; blood ; Intra-Abdominal Fat ; drug effects ; metabolism ; pathology ; Ion Channels ; genetics ; metabolism ; Lipids ; blood ; Male ; Mitochondrial Proteins ; genetics ; metabolism ; Obesity ; blood ; genetics ; pathology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, beta-3 ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Uncoupling Protein 2 ; Weight Loss ; drug effects

BACKGROUNDIt has been shown that the &beta;3-adrenergic receptor (&beta;3-AR) gene Trp64Arg mutation was closely related to obesity and insulin resistance, and may be related to the prevalence of metabolic syndrome (MS). The aim of this study was to investigate the relationship between the &beta;3-AR gene mutation and the prevalence of MS.

METHODSA seven-year follow-up study was initiated in 2000, with 496 samples of simplex obese subjects (body mass index ≥ 25 kg/m(2)) and 248 normal-weight subjects. According to the &beta;3-AR genotypes, the subjects were classified as Trp64 homozygote group and Arg64 carrier group and after 7 years the prevalence of MS was determined.

RESULTSAccording to the baseline profile, there were no significant differences in the adiposity, blood pressure, lipid profile, fasting plasma glucose and fasting insulin between Trp64 homozygote group and Arg64 carrier group either in obesity or normal-weight subjects. The results of follow-up study indicated that in obese men the prevalence rate of MS was much higher in Arg64 carrier group than that in Trp64 homozygote group (54.76% vs. 40.85%, P < 0.05), but there was no statistical difference in women of the above groups. The prevalence rate of MS in obese men of both Trp64 homozygote group and Arg64 carrier obese group were obviously higher than that in women of the above groups (40.85% vs. 18.27% and 54.76% vs 21.28%, all P < 0.005). Differences were not statistically significant in the prevalence of MS for normal weight Trp64 homozygote group and normal weight Arg64 carrier group, either between men, between women, or between men and women. Comparison of populations indicated that no matter with the &beta;3-AR gene mutation or not, the prevalence of MS in obese subjects was significantly higher than normal weight subjects (χ(2) = 28.240 and χ(2) = 15.586, all P < 0.005). Logistic analysis showed that the mutation of &beta;3-AR gene was associated with the prevalence of MS in men.

CONCLUSIONThe mutation of &beta;3-AR gene is the independent risk factor for the prevalence of MS in men.

Adult ; Body Mass Index ; Female ; Follow-Up Studies ; Humans ; Insulin Resistance ; Logistic Models ; Male ; Metabolic Syndrome ; etiology ; genetics ; Middle Aged ; Mutation ; Receptors, Adrenergic, beta-3 ; genetics

We sought to determine the effects of activation of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) on multilocularization of adipocytes in adult white adipose tissue (WAT). Male C57BL/6 normal, db/db, and ob/ob mice were treated with agonists of PPAR-gamma, PPAR-alpha, or beta3-adrenoceptor for 3 weeks. To distinguish multilocular adipocytes from unilocular adipocytes, whole-mounted adipose tissues were co-immunostained for perilipin and collagen IV. PPAR-gamma activation with rosiglitazone or pioglitazone induced a profound change of unilocular adipocytes into smaller, multilocular adipocytes in adult WAT in a time-dependent, dose-dependent, and reversible manner. PPAR-alpha activation with fenofibrate did not affect the number of locules or remodeling. db/db and ob/ob obese mice exhibited less multilocularization in response to PPAR-gamma activation compared to normal mice. Nevertheless, all adipocytes activated by PPAR-gamma contained a single nucleus regardless of locule number. Multilocular adipocytes induced by PPAR-gamma activation contained substantially increased mitochondrial content and enhanced expression of uncoupling protein-1, PPAR-gamma coactivator-1-alpha , and perilipin. Taken together, PPAR-gamma activation induces profound multilocularization and enhanced mitochondrial biogenesis in the adipocytes of adult WAT. These changes may affect the overall function of WAT.
Adipocytes/*cytology/metabolism ; Adipose Tissue, White/*cytology ; Animals ; Cell Nucleus Division ; Hypoglycemic Agents/pharmacology ; Ion Channels/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Obese ; Mitochondria/metabolism ; Mitochondrial Proteins/metabolism ; PPAR alpha/agonists/metabolism ; PPAR gamma/*agonists/*metabolism ; Phosphoproteins/metabolism ; Receptors, Adrenergic, beta-3/agonists ; Thiazolidinediones/pharmacology ; Trans-Activators/metabolism

The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. beta2 adrenergic receptor (beta2-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of beta2-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of beta-arrestin, which is recruited by the phosphorylated beta2-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system.
Adrenergic beta-Agonists/*pharmacology ; Aging/*drug effects ; Animals ; Epinephrine/*pharmacology ; G-Protein-Coupled Receptor Kinase 2/metabolism ; G-Protein-Coupled Receptor Kinase 3/metabolism ; Glucagon/pharmacology ; *Gluconeogenesis/drug effects ; Male ; Models, Biological ; Phosphorylation ; Rats ; Rats, Inbred F344 ; Receptors, Adrenergic, beta-2/agonists/metabolism

The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. beta2 adrenergic receptor (beta2-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of beta2-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of beta-arrestin, which is recruited by the phosphorylated beta2-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system.
Adrenergic beta-Agonists/*pharmacology ; Aging/*drug effects ; Animals ; Epinephrine/*pharmacology ; G-Protein-Coupled Receptor Kinase 2/metabolism ; G-Protein-Coupled Receptor Kinase 3/metabolism ; Glucagon/pharmacology ; *Gluconeogenesis/drug effects ; Male ; Models, Biological ; Phosphorylation ; Rats ; Rats, Inbred F344 ; Receptors, Adrenergic, beta-2/agonists/metabolism

OBJECTIVETo observe the effect of beta(3)-adrenoceptor (AR) in regulating resting intracellular Ca(2+) concentration of the ventricular myocytes and investigate the signaling pathway in rats with experimental heart failure.

METHODSRat models of experimental heart failure were established by ligation of the anterior descending artery, and the myocytes were isolated by enzymatic digestion. The resting intracellular Ca(2+) concentration was determined using laser scanning confocal microscopy (LSCM) in the cells stimulated with 1 micromol/L BRL37344 (a selective beta(3)-AR agonist) alone or in combination with PTX, L-NAME, or methylene blue.

RESULTSIn the ventricular myocytes from normal control rats, BRL373444 reduced the resting intracellular Ca(2+) concentration of by 45.5%, while the reduction increased to 59.4% in the cells from rats with heart failure. In combination with L-NAME (10 micromol/L), methylene blue (10 micromol/L), and PTX (2 microg/ml), BRL373444 caused a reduction in resting intracellular Ca(2+) concentration of the ventricle myocytes from normal control rats by 10.1%, 16.9%, and 15.4%, respectively in control group, while the rate was 16.9%, 19.3%, and 11.7% in the heart failure group.

CONCLUSIONSBeta(3)-AR agonist can decrease the resting intracellular Ca(2+) concentration of the ventricular myocytes, but the reduction is smaller in cells from rats with heart failure than in cells of normal rats. This effect is mediated through the PTX-NOS-NO pathway.

Adrenergic Agonists ; pharmacology ; Adrenergic beta-3 Receptor Agonists ; Animals ; Calcium ; metabolism ; Heart Failure ; chemically induced ; metabolism ; pathology ; Heart Ventricles ; pathology ; In Vitro Techniques ; Intracellular Space ; drug effects ; metabolism ; Male ; Myocytes, Cardiac ; drug effects ; metabolism ; pathology ; Rats ; Rats, Wistar ; Receptors, Adrenergic, beta-3 ; metabolism ; Rest ; Signal Transduction ; drug effects