Association of BMI with the beta3-adrenergic receptor gene polymorphism in Japanese: meta-analysis

Differential Effect of Fat Intake on Blood Pressure in Healthy Japanese Women with and without the Variant of Fat Mass and Obesity-Associated Gene

A high-fat diet is believed to be a risk factor for hypertension through inducing obesity. It has been reported that variants of the fat mass and obesity-associated (FTO) and beta-3 adrenergic receptor (B3AR) genes are associated with obesity and blood pressure. The purpose of this study was to investigate the effect of dietary fat on blood pressure with or without the variant of the FTO and B3AR genes. A total of 227 healthy Japanese women aged 18 to 64 years were recruited for measurement of nutrient intake and blood pressure. The single nucleotide polymorphism rs9939609 of the FTO gene and rs4994 of the B3AR gene were genotyped. Spearman's rank correlation coefficient was applied to investigate the relationship between fat intake and blood pressure. A hierarchical multiple regression analysis was performed to determine whether the genotype interacts with fat intake to affect blood pressure. No significant correlations were found between fat intake and either systolic or diastolic blood pressure. A significant negative correlation was found between fat intake and both blood pressures in the FTO-gene-variant group, but not in the normal-FTO-gene group. In hierarchical multiple regression analysis, the interaction of fat intake and the gene variant showed significance, and the change in coefficient of determination (R ²) was significantly increased with increases of the interaction variable. These results indicate that the effect of fat intake on blood pressure may be modified by the variant of the FTO gene such that a high-fat diet intake may be associated with a decrease of systolic and diastolic blood pressure in healthy Japanese women with the FTO variant. Our results did not support the hypothesis that a high-fat diet increases blood pressure.

Anti-Diabesity Middle Eastern Medicinal Plants and Their Action Mechanisms

Over the last four decades, the escalation in diabetes and obesity rates has become epidemic all over the world. Diabesity describes the strong link between T2D and obesity. It correlates deeper with the elevated risks of developing cardiovascular disease hypertension, stroke, and several malignancies. Therapeutic usage of medicinal plants and natural products in the treatment of diabetes and obesity has long been known to physicians of Greco-Arab and Islamic medicine. Improved versions of their abundant medicinal plant-based formulations are at present some of the most popular herbal treatments used. Preclinical and clinical data about medicinal plants along with their bioactive constituents are now available, justifying the traditionally known therapeutic uses of products derived from them for the prevention and cure of obesity-related T2D and other health problems. The aim of this review is to systematize published scientific data dealing with the efficiency of active ingredients or extracts from Middle Eastern medicinal plants and diet in the management of diabesity and its complications. Google Scholar, MEDLINE, and PubMed were searched for publications describing the medicinal plants and diet used in the management of T2D, obesity, and their complications. The used keywords were “medicinal plants” or “herbals” in combination with “obesity,” “diabetes,” “diabetes,” or nephropathy. More than 130 medicinal plants were identified to target diabesity and its complications. The antidiabetic and anti-obesity effects and action mechanisms of these plants are discussed here. These include the regulation of appetite, thermogenesis, lipid absorption, and lipolysis; pancreatic lipase activity and adipogenesis; glucose absorption in the intestine, insulin secretion, glucose transporters, gluconeogenesis, and epigenetic mechanisms.

The Association of Trp64Arg Polymorphism in the Beta-Adrenergic Receptor With Insulin Resistance: Meta-Analysis

BACKGROUND

Insulin resistance is a metabolic disorder that occurs in type 2 diabetes mellitus and obesity. Genetic factors such as β3-adrenoceptor polymorphism (Trp64Arg) may be involved in IR and insulin secretion. However, their association is controversial. Therefore, the current meta-analysis was conducted to clarify the relationship between the Trp64Arg and IR.

METHODS

The literature search was performed in PubMed, Embase, and Web of Science using the keywords "Receptors, Adrenergic, beta-3, Receptors, Adrenergic, Insulin Resistance, Protein-Coupled Receptor Kinase 3" from 2005 to February 7, 2021. We used a random-effects model to calculate the pooled effect size. We conducted subgroup analysis and regression analysis to identify sources of heterogeneity; and Egger's test and funnel plot were used to test publication bias. Finally, we conducted a sensitivity analysis.

RESULTS

We included eight papers with 1,586 subjects. There was a positive correlation between Trp64Arg mutation and insulin level (standardized mean difference = 0.20, 95% confidence intervals: 0.00 to 0.39, I² = 57.6%, p = 0.016). However, there was no association between Trp64Arg and the homeostasis model (HOMA-IR) assessment. Egger's tests showed no publication bias; the sensitivity analysis showed that our results were stable. Regression analysis revealed no source of heterogeneity.

CONCLUSION

Trp64Arg may be associated with IR. European ancestry, obesity, plasma insulin level, and test status may be potential factors affecting the relationship between Trp64Arg and IR.

Beta-3-adrenergic Receptor rs4994 Polymorphism Is a Potential Biomarker for the Development of Nonalcoholic Fatty Liver Disease in Overweight/Obese Individuals

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. Obesity is the most common and well-established risk factor for NAFLD, but there are large interindividual differences in the relationship between weight status and the development of NAFLD. Beta-3-adrenergic receptor (ADRB3) plays a key role in the development of visceral obesity and insulin resistance; however, the effect of ADRB3 polymorphisms on the risk of NAFLD remains unclear. We investigated whether or not a common rs4994 polymorphism (T190C) in the ADRB3 gene is associated with the risk of NAFLD through an increase in the body mass index (BMI) among the general population. We performed cross-sectional and longitudinal analyses in a total of 591 Japanese health screening program participants. Among the overweight or obese subjects, but not normal-weight subjects, individuals with the C/C genotype had a higher risk of developing NAFLD in comparison to those with other genotypes in the cross-sectional analysis (odds ratio: 4.40, 95% confidence interval (CI): 1.08–17.93). Meanwhile, the receiver operating characteristic curve indicated that the association between an increase in the BMI and the presence of NAFLD in subjects with the C/C genotype (area under the curve: 0.91, 95% CI: 0.78–1.00) was more pronounced in comparison to subjects with other genotypes. These above-described findings were verified by the analyses using a replicated data set consisting of 5,000 random samples from original data sets. Furthermore, among the 291 subjects for whom longitudinal medical information could be collected and who did not have NAFLD at baseline, the Cox proportional hazard model also confirmed that overweight or obese status and the C/C genotype were concertedly related to the increased risk of NAFLD development. These results suggest that genotyping the ADRB3 rs4994 polymorphism may provide useful information supporting the development of personalized BMI-based preventive measures against NAFLD.

Genetic variants influencing obesity-related traits in Japanese population

Context: Adipose tissue is the main organ that stores energy and participates in adaptive thermogenesis of the human body. The adipose tissue content in an individual is determined by a combination of genetic factors and lifestyle related factors. While Japanese people, along with the closely related East Asians, are generally thinner than individuals of European ancestry, they are prone to accumulating visceral adipose tissues. Genome-wide discovery of loci influencing obesity-related traits, and application of the genome sequence data to assess natural selection, provides evidence that the obesity-related traits in East Asians might be shaped by natural selection. Objective: This review aims to summarise health and evolutionary implications of genetic variants influencing obesity-related traits in Japanese. Methods: This study gathered recently published papers of medical, genetic and evolutionary studies regarding obesity-related traits in the Japanese and closely related East Asians. Results and conclusion: A high susceptibility to central obesity of Japanese and closely related East Asians might have been shaped by natural selection favouring thrifty genotypes. Moreover, natural selection favouring higher thermogenic activity of brown adipose tissues would contribute to increased non-thrifty alleles in ancestors of East Asians.

Dietary Fatty Acids and the Metabolic Syndrome: A Personalized Nutrition Approach

Dietary fatty acids are present in a wide variety of foods and appear in different forms and lengths. The different fatty acids are known to have various effects on metabolic health. The metabolic syndrome (MetS) is a constellation of risk factors of chronic diseases. The etiology of the MetS is represented by a complex interplay of genetic and environmental factors. Dietary fatty acids can be important contributors of the evolution or in prevention of the MetS; however, great interindividual variability exists in the response to fatty acids. The identification of genetic variants interacting with fatty acids might explain this heterogeneity in metabolic responses. This chapter reviews the mechanisms underlying the interactions between the different components of the MetS, dietary fatty acids and genes. Challenges surrounding the implementation of personalized nutrition are also covered.

12-Week aerobic exercise and nutritional program minimized the presence of the 64Arg allele on insulin resistance

BACKGROUND

The objective of the study was to investigate the response of 64Arg allele carriers of the ADRB3 gene (Trp64Arg polymorphism) in the anthropometric, cardiorespiratory and metabolic variables in overweight adolescents after a 12-week aerobic exercise and nutritional program.

METHODS

A total of 92 overweight adolescents, 10-16 years old and of both genders, participated. Body composition, waist circumference (WC), pubertal stage status, blood pressure, glucose, insulin and lipid profile and direct maximal oxygen uptake were assessed at baseline and after 12 weeks of a training program. The homeostasis metabolic assessments [homeostasis model assessment of insulin resistance (HOMA-IR)] and quantitative insulin sensitivity check index (QUICKI) were determined and the Trp64Arg polymorphism of the ADRB3 gene was investigated by Taqman single nucleotide polymorphism (SNP) genotyping assays. Exercise sessions consisted of 100-min aerobic exercise and 20-min stretching, 3 times a week, totalizing 36 sessions. Multivariate analysis of variance (MANOVA), analysis of covariance (ANCOVA) and effect size were used for variables, with p<0.05 considered significant.

RESULTS

In baseline, HOMA-IR was higher in carriers of the 64Arg allele and decreased more after 12 weeks than in non-carriers (p=0.01). The anthropometric, physical fitness and metabolic profiles had similar responses after training in carriers and non-carriers.

CONCLUSIONS

Overweight adolescents present changes in body composition and physical fitness, independent of Trp64Arg genotypes. However, a 12-week aerobic exercise and nutritional program promoted greater reductions in insulin resistance in carriers of the 64Arg allele.

ADRB3 polymorphism rs4994 (Trp64Arg) associates significantly with bodyweight elevation and dyslipidaemias in Saudis but not rs1801253 (Arg389Gly) polymorphism in ARDB1

Background

In some populations, obesity and body weight related disorders show a correlation with polymorphisms in three subtypes of beta-adrenoceptor (β1, β2, and β3) [ADRB1, ADRB2 and ADRB3] genes. We scanned for the polymorphism of Arg389Gly (rs1801253) in ADRB1 and Trp64Arg (rs4994) in ADRB3 genes in Saudi population to determine association, if any, of these polymorphisms with obesity and related disorders.

Methods

We studied 329 non-related adults (33.1% men and 66.9% women), aged 18–36 years. Anthropometric measurements were recorded, and Body mass index (BMI) and waist/hip ratio were calculated; leptin, insulin, lipidogram, and glucose concentrations were determined. ADRB1 and ADRB3 polymorphisms (Arg389Gly and Trp64Arg, respectively) were screened by DNA sequencing. The subjects were divided into three groups according to BMI: normal weight (BMI < 25 kg/m²), overweight (BMI ≥25.1–29.9 kg/m²) subjects, and obese (≥30 kg/m²).

Results

In the age-matched groups of the normal weight, overweight and obese male and female subjects, all anthropometric parameters were found to be significantly higher, and in the obese group, all biochemical parameters were significantly elevated compared to the normal weight controls. The allelic frequency of Gly389 ADRB1 did not differ amongst the three groups, whereas the frequency of Arg64 of ADRB3 gene was significantly higher in the overweight and obese subjects, compared with the normal weight subjects. In addition, subjects carrying Arg64 allele regardless of their BMI had a greater waist and hip circumference, W/H ratio, plasma cholesterol, triglyceride, LDL, leptin, insulin, and glucose level compared to those with the wild-type Trp allele.

Conclusion

The results of this study have shown a significant association between the Trp64Arg polymorphism in ADRB3 gene and the development of overweight and obesity in Saudi populations. It also has an influence on the levels of lipid, insulin, leptin, and glucose, whereas, Arg389Gly polymorphism in ADRB1 is not associated with overweight, obesity or dyslipidaemias in Saudis.

Association of β3-adrenergic receptor rs4994 polymorphisms with the risk of type 2 diabetes: A systematic review and meta-analysis

AIM

The association of ADRB3 polymorphism with the risk of T2DM remains unclear perhaps due to different ethnicities and small study sizes. We systemically evaluated the association of β3-adrenergic receptor(ADRB3)rs4994 and type 2 diabetes(T2DM) by pooling all of the case-control studies reported, and also elucidated the association according to the ethnicity and obesity of the subjects.

METHODS

A literature search was conducted using PubMed, EMBASE, Cochrane Library, Korean scientific database, Chinese medical databases, and the Indian medical database to identify eligible studies for determining the association of ADRB3 rs4994 and T2DM risk. The association was examined in five genetic models: the allelic(AG), recessive(RG), dominant(DG), homozygous(HMG), and heterozygous(HTG) genetic models. Subgroup analyses stratified by ethnicity(Asians and others) were assessed.

RESULTS

This meta-analysis included 17 eligible studies meeting Hardy-Weinberg equilibrium consisting of 4864 patients with T2DM(cases) and 8779 people without diabetes(controls). All models had no heterogeneity or publication bias in the meta-analysis including all subjects. ADRB3 rs4994 polymorphism of all subjects was significantly associated with an increased risk of T2DM in all genetic models with random effects: AG(OR=1.18, 95% CI: 1.05-1.32), RG(OR=1.76, 95% CI: 1.27-2.42), DG(OR=1.16, 95% CI: 1.03-1.30), HMG (OR=1.78, 95% CI: 1.25-2.52), and HTG(OR=1.11, 95% CI: 1.01-1.23). Furthermore, in sub-group analysis all models except HTG exhibited significant associations between T2DM and ADRB3 in Asians. However, the non-Asian group had no significant association in any genetic models with random effects.

CONCLUSIONS

Middle-age adult Asians with the ADRB3 rs4994 minor alleles are at increased risk of T2DM.

Obesity is associated with the Arg389Gly ADRB1 but not with the Trp64Arg ADRB3 polymorphism in children from San Luis PotosÍ and León, México

This research was designed to analyze the possible associations of Arg389Gly ADRB1 and Trp64Arg ADRB3 polymorphisms in children with obesity. A cross-sectional study included 1,046 school-age Mexican participants (6-12 years old) from the cities of San Luis PotosÍ and León. Children were classified as non-obese or obese according to their body mass index (BMI) percentile; obese children had a BMI≥95th percentile for sex and age. Biochemical data were collected. Polymorphisms were detected using TaqMan qPCR assay. A logistic regression analysis was used to calculate the risk of obesity based on genotypes. Differences were found between groups where obese children had a significant increase in systolic and diastolic blood pressure, fasting plasma glucose, insulin, HOMA-IR, LDL-cholesterol, triglycerides, and lower HDL-cholesterol compared with the normal weight group (P<0.05). The distribution of allele frequency in the population was Arg= 87.4 and Gly= 12.6 (Hardy Weinberg equilibrium c² = 3.16 , P = 0.07 ); Trp= 81.5 and Arg= 18.5 (Hardy Weinberg equilibrium c² = 2.2, P = 0.14 ) for ADRB1 and ADRB3, respectively. Even though no different frequencies of Arg389Gly polymorphism between groups were found (P = 0.08), children carriers of one Gly389 ADRB1 allele had a risk for obesity of OR=1.40 (95%CI, 1.03-1.90, P = 0.03) after adjustment for age and gender. No other association was found for Trp64Arg ADRB3 polymorphism. Only the Arg389Gly ADRB1 polymorphism was associated with risk for obesity in Mexican children.

Association between Genetic Polymorphisms of the Beta Adrenergic Receptor and Diurnal Intraocular Pressure in Chinese Volunteers and Glaucoma Patients

PURPOSE

To evaluate the relationship between genetic polymorphisms of the beta adrenergic receptor (ADR) and diurnal intraocular pressure (IOP) in Chinese healthy volunteers, normal tension glaucoma (NTG) patients, and primary open-angle glaucoma (POAG) patients.

METHODS

Fifty healthy volunteers (control group), 55 untreated NTG patients, and 55 untreated POAG patients were recruited. IOP of both eyes was measured at 3-hour intervals from 0600 to 2400 hours. For control group, IOP data from the eye with better mean deviation (MD) of visual field was used for statistical analysis. For glaucoma patients, IOP data from the eye with a greater visual field defect was used for statistical analysis. Genetic polymorphisms of ADR were determined by direct DNA sequencing. The relationship between IOP and genetic polymorphisms was statistically analyzed.

RESULTS

R16G (A/G), L84L (G/A), and R175R (C/A) in β2-ADR showed significantly different allele in the three groups (p = 0.005, p = 0.045, and p = 0.045, respectively). For the POAG group, C/C of R389G (C/G) in β1-ADR had a significantly lower diurnal mean IOP (p < 0.001), peak IOP (p = 0.010), trough IOP (p < 0.001), and larger IOP range (p = 0.047) than G carriers; C/C of R389G (C/G) in β1-ADR and G carriers had parallel diurnal IOP curves but significantly different diurnal IOP levels (p = 0.001); C/C of Q27E (C/G) in β2-ADR had a significantly higher diurnal mean IOP (p = 0.045) than G carriers; G/G of L84L (G/A) in β2-ADR had a significantly higher diurnal mean IOP (p = 0.044) than A carriers; C/C of R175R (C/A) in β2-ADR had a significantly higher diurnal mean IOP (p = 0.044) than A carriers; T/T of W64R (T/C) in β3-ADR had a significantly smaller IOP range (p = 0.001) than C carriers.

CONCLUSION

Certain polymorphisms of β2-ADR showed significantly different genotype frequencies in healthy volunteers untreated NTG patients, and POAG patients. Polymorphisms of the β-ADR gene may alter the untreated IOP level of POAG patients.

Genetic variants influencing effectiveness of exercise training programmes in obesity - an overview of human studies

Frequent and regular physical activity has significant benefits for health, including improvement of body composition and help in weight control. Consequently, promoting training programmes, particularly in those who are genetically predisposed, is a significant step towards controlling the presently increasing epidemic of obesity. Although the physiological responses of the human body to exercise are quite well described, the genetic background of these reactions still remains mostly unknown. This review not only summarizes the current evidence, through a literature review and the results of our studies on the influence of gene variants on the characteristics and range of the body's adaptive response to training, but also explores research organization problems, future trends, and possibilities. We describe the most reliable candidate genetic markers that are involved in energy balance pathways and body composition changes in response to training programmes, such as FTO, MC4R, ACE, PPARG, LEP, LEPR, ADRB2, and ADRB3. This knowledge can have an enormous impact not only on individualization of exercise programmes to make them more efficient and safer, but also on improved recovery, traumatology, medical care, diet, supplementation and many other areas. Nevertheless, the current studies still represent only the first steps towards a better understanding of the genetic factors that influence obesity-related traits, as well as gene variant x physical activity interactions, so further research is necessary.

Effects of lifestyle intervention on weight and metabolic parameters in patients with impaired glucose tolerance related to beta-3 adrenergic receptor gene polymorphism Trp64Arg(C/T): Results from the Japan Diabetes Prevention Program

The beta‐3 adrenergic receptor (ADRB3), primarily expressed in adipose tissue, is involved in the regulation of energy metabolism. The present study hypothesized that ADRB3 (Trp64Arg, rs4994) polymorphisms modulate the effects of lifestyle intervention on weight and metabolic parameters in patients with impaired glucose tolerance. Data were analyzed from 112 patients with impaired glucose tolerance in the Japan Diabetes Prevention Program, a lifestyle intervention trial, randomized to either an intensive lifestyle intervention group or usual care group. Changes in weight and metabolic parameters were measured after the 6‐month intervention. The ADRB3 polymorphisms were determined using the polymerase chain reaction restriction fragment length polymorphism method. Non‐carriers showed a greater weight reduction compared with the carriers in both the lifestyle intervention group and usual care group, and a greater increase of high‐density lipoprotein cholesterol levels than the carriers only in the lifestyle intervention group. ADRB3 polymorphisms could influence the effects of lifestyle interventions on weight and lipid parameters in impaired glucose tolerance patients.

Carnitine palmitoyltransferase 1B 531K allele carriers sustain a higher respiratory quotient after aerobic exercise, but β3-adrenoceptor 64R allele does not affect lipolysis: a human model

Carnitine palmitoyltransferase IB (CPT1B) and adrenoceptor beta-3 (ADRB3) are critical regulators of fat metabolism. CPT1B transports free acyl groups into mitochondria for oxidation, and ADRB3 triggers lipolysis in adipocytes, and their respective polymorphisms E531K and W64R have been identified as indicators of obesity in population studies. It is therefore important to understand the effects of these mutations on ADRB3 and CPT1B function in adipose and skeletal muscle tissue, respectively. This study aimed to analyze the rate of lipolysis of plasma indicators (glycerol, free fatty acids, and beta hydroxybutyrate) and fat oxidation (through the non-protein respiratory quotient). These parameters were measured in 37 participants during 30 min of aerobic exercise at approximately 62% of maximal oxygen uptake, followed by 30 min of recovery. During recovery, mean respiratory quotient values were higher in K allele carriers than in non-carriers, indicating low post-exercise fatty acid oxidation rates. No significant differences in lipolysis or lipid oxidation were observed between R and W allele carriers of ADRB3 at any time during the aerobic load. The substitution of glutamic acid at position 531 by lysine in the CPT1B protein decreases the mitochondrial beta-oxidation pathway, which increases the non-protein respiratory quotient value during recovery from exercise. This may contribute to weight gain or reduced weight-loss following exercise.

Higher cardiorespiratory fitness attenuates the risk of atherosclerosis associated with ADRB3 Trp64Arg polymorphism

PURPOSE

β3-Adrenergic receptor (ADRB3) Trp64Arg polymorphism is associated with atherogenic risk factors that include weight gain, insulin resistance, and diabetes. Habitual exercise brings higher cardiorespiratory fitness and results in the amelioration of atherosclerotic risk factors. However, the effects of cardiorespiratory fitness level and ADRB3 Trp64Arg polymorphism on the risk of cardiovascular disease remain unclear. A cross-sectional investigation of 877 Japanese men and women (18-75 years old) was performed to clarify the effects of cardiorespiratory fitness on the relationship between ADRB3 Trp64Arg polymorphism and risk of cardiovascular disease.

METHOD

Common carotid intima-media thickness (ccIMT) and blood lipid profiles were assessed as surrogate markers of atherosclerosis. We measured peak oxygen uptake (V̇O(2peak)) during incremental cycle ergometer exercise testing. Subjects were divided into groups with high (High-Fit) and low (Low-Fit) levels of cardiorespiratory fitness based on the median value of V̇O(2peak) for sex and decade.

RESULTS

Levels of body fat, triglycerides, and plasma glucose were lower and high-density lipoprotein cholesterol levels and V̇O(2peak) were higher in High-Fit subjects than Low-Fit subjects. ADRB3 Trp64Arg polymorphism did not significantly affect ccIMT or blood lipid profiles. In Low-Fit subjects, ccIMT was higher in individuals with the Arg/Arg genotype compared to the Trp/Trp and Trp/Arg genotypes (each P < 0.0001); however, ADRB3 polymorphism had no effect in High-Fit subjects.

CONCLUSION

Higher levels of cardiorespiratory fitness may attenuate the risk of atherosclerosis associated with ADRB3 Trp64Arg polymorphism.

Incidence of β3-adrenergic receptor polymorphism and prediction of successful weight reduction with mazindol therapy in severely obese Japanese subjects

SUMMARY

Mazindol, a centrally acting monoamine re-uptake inhibitor, enhances satiety and supports body weight loss, but response to this drug among obese patients is very variable. The possible involvement of the Trp64Arg polymorphism of the β3-adrenergic receptor (ADRB3) gene in the development of severe obesity and weight loss response to anorexigenic drugs has not been established. In the present study, the allelic frequency of the Trp64Arg ADRB3 gene polymorphism was determined in massively obese Japanese outpatients (BMI > 35 kg/m(2)), and we investigated whether allelic differences may determine the weight loss effect of mazindol. The allelic frequency of Trp64Arg heterozygotes and homozygotes did not differ in severely obese subjects compared to non-obese subjects. Trp64Arg heterozygotes experienced significantly increased weight loss and reduced blood pressure following mazindol administration for 12 weeks. Thus the ADRB3 gene polymorphism is predictive for difficulty in weight reduction with mazindol treatment, but is not related to the development of severe obesity in the Japanese population.:

From obesity genetics to the future of personalized obesity therapy

Obesity is a disorder characterized by an excess accumulation of body fat resulting from a mismatch between energy intake and expenditure. Incidence of obesity has increased dramatically in the past few years, almost certainly fuelled by a shift in dietary habits owing to the widespread availability of low-cost, hypercaloric foods. However, clear differences exist in obesity susceptibility among individuals exposed to the same obesogenic environment, implicating genetic risk factors. Numerous genes have been shown to be involved in the development of monofactorial forms of obesity. In genome-wide association studies, a large number of common variants have been associated with adiposity levels, each accounting for only a small proportion of the predicted heritability. Although the small effect sizes of obesity variants identified in genome-wide association studies currently preclude their utility in clinical settings, screening for a number of monogenic obesity variants is now possible. Such regular screening will provide more informed prognoses and help in the identification of at-risk individuals who could benefit from early intervention, in evaluation of the outcomes of current obesity treatments, and in personalization of the clinical management of obesity. This Review summarizes current advances in obesity genetics and discusses the future of research in this field and the potential relevance to personalized obesity therapy.

Brown adipose tissue in adult humans: a metabolic renaissance

Brown adipose tissue (BAT) plays a key role in energy homeostasis and thermogenesis in animals, conferring protection against diet-induced obesity and hypothermia through the action of uncoupling protein 1 (UCP1). Recent metabolic imaging studies using positron emission tomography computerized tomography (PET-CT) scanning have serendipitously revealed significant depots of BAT in the cervical-supraclavicular regions, demonstrating persistence of BAT beyond infancy. Subsequent cold-stimulated PET-CT studies and direct histological examination of adipose tissues have demonstrated that BAT is highly prevalent in adult humans. BAT activity correlates positively with increment of energy expenditure during cold exposure and negatively with age, body mass index, and fasting glycemia, suggesting regulatory links between BAT, cold-induced thermogenesis, and energy metabolism. Human BAT tissue biopsies express UCP1 and harbor inducible precursors that differentiate into UCP1-expressing adipocytes in vitro. These recent discoveries represent a metabolic renaissance for human adipose biology, overturning previous belief that BAT had no relevance in adult humans. They also have implications for the understanding of the pathogenesis and treatment of obesity and its metabolic sequelae.

Beta-3-adrenergic receptor Trp64Arg polymorphism: does it modulate the relationship between exercise and percentage of body fat in young adult Japanese males?

OBJECTIVES

The Trp64Arg polymorphism of the beta-3-adrenergic receptor gene has been studied as a potential genetic factor contributing to the development of obesity. Several studies have investigated whether or not this polymorphism affects weight reduction due to exercise, but the results of these studies have not been consistent. Moreover, information on a population characterized by a wide ranges of physical activities is scarce. Thus, to further understand the impact of this polymorphism, we examined whether the polymorphism modulates the relationship between physical activity due to exercise (PAE) and percentage of body fat (%BF).

METHODS

The study population was 70 Japanese male young adults with a high prevalence of habitual exercise. PAE was estimated by a questionnaire, and %BF was measured by bioelectrical impedance analysis. Genotyping was done by PCR-restriction fragment length polymorphism analysis.

RESULTS

The median PAE value of the subjects was 6.9 MET-h/day with an interquartile range of 1.5-10.3 MET-h/day. PAE correlated significantly with %BF in the entire population and within the two subpopulations, namely, carriers or non-carriers of the Arg allele. Multiple regression analysis of PAE, Trp64Arg polymorphism, and the interaction term revealed that while the PAE-derived independent variable was statistically significant, the interaction term was insignificant. When the two regression lines of subjects with and without the Arg allele were considered, the difference between the two slopes did not deviate from zero, nor did the vertical distance of the two regression lines. These findings suggest that the impact of this polymorphism is limited.

CONCLUSIONS

In our study population of young adult Japanese males, the impact of the Trp64Arg polymorphism on the association between exercise and body composition was weak, if it existed at all.

Meta-Analysis of the Association of the Trp64Arg Polymorphism in the β3 Adrenergic Receptor with Insulin Resistance

OBJECTIVE

To clarify the possible association between the Trp64Arg polymorphism and insulin resistance (IR).

RESEARCH METHODS AND PROCEDURES

Articles evaluating the effect of the Trp64Arg polymorphism on IR were identified on the MEDLINE and PubMed databases from 1995 to February, 2004. After extraction of relevant data, main and subgroup meta-analyses were performed to assess the differences in IR indices between Trp/Trp and Trp/Arg genotypes.

RESULTS

Forty eligible papers containing 56 subgroups were included in this meta-analysis. Among a total of 12,805 subjects, 21.9% had Trp64Arg mutation: 20.8%, heterozygotes and 1.1%, homozygotes. Significant associations were found between this mutation and some indices of IR. The weighted mean difference in fasting insulin, 120-minute insulin level after oral glucose tolerance test, and homeostasis model assessment between Arg64 and Trp64 was 0.23 [95% confidence interval (CI), 0.05 to 0.42] pM, 0.89 (95% CI, 0.30 to 1.48) pM, and 0.55 (95% CI, 0.14 to 0.96), respectively. Subgroup analysis further indicated that this significant association existed only in the Asian population (p < 0.01) and in the obese (p = 0.02) and diabetes subgroups (p = 0.03).

DISCUSSION

Numerous studies have been conducted to examine the relationship between the beta3-adrenergic receptor Trp64Arg polymorphism and components of IR syndrome. However, the results have been inconsistent and have led to controversy about whether this polymorphism is associated with these clinical features. The current meta-analysis demonstrated the moderate effects of the Trp64Arg polymorphism on IR in the Asian population and in obese and diabetic subgroups.

ADRB3 polymorphism associated with BMI gain in Japanese men

Objective. The aim of this study was to evaluate the association between the Trp64Arg polymorphism in the beta3-adrenergic receptor gene (ADRB3: rs4994) and BMI and serological and anthropometric data in healthy Japanese. Methods. Healthy Japanese recruited in a large-scale integrated manufacturing facility in Japan (N = 1355; age: 37.25 ± 9.43; BMI: 22.86 ± 3.46) were eligible for analysis. The anthropometric data and serological data were measured during a comprehensive health check, and a self-reporting questionnaire was used to assess lifestyle habits (current exercise, smoking status, alcohol intake, and working style) and weight at age 20. Genotyping for the ADRB3 polymorphism was performed by PCR-RFLP method. Results. Among 1355 participants, the genotype frequencies of the Trp/Trp, Trp/Arg, and Arg/Arg variants were 920 (67.9%), 394 (29.1%), and 41 (3.05%), respectively. In the multivariate analysis, a multiple linear regression model in men for the adjustment of age, drinking habits, smoking habits, exercise habits, working status and serological measurements statistically showed an overall weak significance between annual BMI gain from age 20 and age, LDL or ADRB3 polymorphism. Conclusions. The level of LDL, age, and ADRB3 polymorphism (Arg/Arg genotype) were statistically associated with annual BMI gain in Japanese men.

An association between TRP64ARG polymorphism of the B3 adrenoreceptor gene and some metabolic disturbances

Backgrounds

B3 adrenoreceptors (ADRB3) are abundant in adipose tissue and play the role in its metabolism and lipolysis. Some variants of the ADRB3 gene may predispose subjects for the development obesity and metabolic abnormalities in the setting of modern sedentary lifestyle. ADRB3 gene polymorphism association with metabolic disturbances has never been studied before in the ethnic Kyrgyz population.

Aim

To study an association between Trp64Arg polymorphism of the ADRB3 and metabolic syndrome (MS) components in an ethnic Kyrgyz group.

Materials and methods

213 Ethnic Kyrgyz volunteers over the age of 30 were enrolled in the study. The assessment plan for each individual comprised of general physical and anthropometric exams as well as laboratory tests (glucose, lipid panel, insulin) and genotyping by Trp64Arg polymorphism of the ADRB3. MS diagnosis was consistent with modified ATP III criteria (2005). Logistic regression analysis was performed to test the potential independent association between Arg64 allele with obesity, abdominal obesity (AO) and arterial hypertension (AH).

Results

Trp64Arg polymorphism of the ADRB3 was assessed in 213 individuals (145 men, 68 women) aged 30-73 (mean age 50.7 ± 7.6). Arg64 allele frequency was 0.239; ADRB3 genotype distribution among participants was: Trp64 homozygotes 54.5%, Trp64Arg 43.2% and Arg64 homozygotes 2.3%. There was an association between Trp64Arg и Arg64Arg genotypes and higher BMI, WC and obesity frequency (p < 0.00009), AO (p < 0.01), type 2 diabetes mellitus (DM) (p < 0.005) and lower high density cholesterol (HDL-C) level (p < 0.03). The logistic regression analysis showed the correlation of the Arg64 allele with obesity (OR 3.159; 95% CI 1.789-5.577) and AO (OR 1.973; 95% CI 1.118-3.481). The association between Arg64 allele and AH lost its significance after adjustment for obesity.

Conclusion

Arg64 allele of the ADRB3 gene in the studied group has an association with MS components such as obesity, AO and decreased HDL-C level.

Pharmacogenomics of β-adrenergic receptor physiology and response to β-blockade

Myocardial β-adrenergic receptors (βARs) are important in altering heart rate, inotropic state, and myocardial relaxation (lusitropy). The β1AR and β2AR stimulation increases cyclic adenosine monophosphate concentration with the net result of myocyte contraction, whereas β3AR stimulation results in decreased inotropy. Downregulation of β1ARs in heart failure, as well as an increased β3AR activity and density, lead to decreased cyclic adenosine monophosphate production and reduced inotropy. The βAR antagonists are commonly used in patients with coronary artery disease and heart failure; however, perioperative use of βAR antagonists is controversial. Individual patient's response to beta-blocker therapy is an area of intensive research, and apart from pharmacokinetics, pharmacodynamics, and ethnic differences, genetic alterations have become more important in the last 20 years. The most common genetic variants in humans are single nucleotide polymorphisms (SNPs). There are 2 clinically relevant SNPs for the β1AR (Ser49Gly, Arg389Gly), 3 for the β2AR (Arg16Gly, Gln27Glu, Thr164Ile), and 1 for the β3AR (Trp64Arg). Although results are somewhat controversial, generally large datasets have the potential to show a relationship between βAR SNPs and outcomes such as development and progression of heart failure, coronary artery disease, vascular reactivity, hypertension, asthma, obesity, and diabetes. Although βAR SNPs may not directly cause disease, they appear to be risk factors for, and modifiers of, disease and the response to stress and drugs. In the perioperative setting, this has specifically been demonstrated for the Arg389Gly β1AR polymorphism with which patients with the Gly variant had a higher incidence of adverse perioperative events. Knowing that genetic variants play an important role, perioperative medicine will likely change from simple therapeutic intervention to a more personalized way of adrenergic receptor modulation.

Influence of beta 3-adrenergic receptor Trp64Arg polymorphism on the improvement of metabolic syndrome by exercise-based intervention in Japanese middle-aged males

SUMMARY

OBJECTIVES

To date, there have been few intervention studies concerning the association of metabolic syndrome with beta 3-adrenergic receptor (ADRB3) Trp64Arg polymorphism, although ADRB3 Trp64Arg polymorphism has been reported to be associated with weight gain and insulin resistance by several intervention programs. We examined the influence of ADRB3 Trp64Arg polymorphism on the improvement of metabolic syndrome by an exercise-based intervention program.

METHODS

Thirty-six male employees who satisfied the metabolic syndrome criteria participated in a three-month exercise-based intervention program (average age, 49 ± 6 years old). The improvement rate of metabolic syndrome after the intervention was compared between subjects with and without ADRB3 Trp64Arg polymorphism. The Mantel-Haenszel test was employed to adjust the age, diet, and exercise in analysis of the influence of ADRB3 Trp64Arg polymorphism on metabolic syndrome. The Trp64Arg genotype of the β3-adrenoceptor gene was examined in peripheral blood leukocyte DNA by TaqMan PCR assay.

RESULTS

The distribution of polymorphism was 23 (Trp/Trp), 13 (Trp/Arg), and 0 (Arg/Arg). The metabolic syndrome improvement rates after intervention were 21.7% (Trp/Trp) and 53.8% (Trp/Arg) (p = 0.050). After adjustment individually for age, calorie limitation, and 10,000 or more and 12,000 or more steps of walking per day during intervention, the odds ratios of the Trp/Arg genotype for improvement of metabolic syndrome relative to that of the Trp/Trp genotype were 5.1 (p = 0.043), 4.9 (p = 0.051), 3.7 (p = 0.074), and 5.0 (p = 0.045), respectively.

CONCLUSION

The results suggested that ADRB3 Trp64Arg polymorphism influences the metabolic syndrome improvement rate by exercise-based intervention program.

Relationships of adrenoceptor polymorphisms with obesity

Obesity, hypertension, and type 2 diabetes are rapidly growing public health problems. Heightened sympathetic nerve activity is a well-established observation in obesity, hypertension, and type 2 diabetes. Human obesity, hypertension, and diabetes have strong genetic as well as environmental determinants. Reduced energy expenditure and resting metabolic rate are predictive of weight gain, and the sympathetic nervous system participates in regulating energy balance through thermogenesis. The thermogenic effects of catecholamines in obesity are mainly mediated via the β2, and β3-adrenergic receptors in humans. Further, β2-adrenoceptors importantly influence vascular reactivity and may regulate blood pressure. β-adrenoceptor polymorphisms have also been associated with adrenoceptor desensitization, increased adiposity, insulin resistance, and enhanced sympathetic nervous activity. Many epidemiological studies have shown strong relationships between adrenoceptor polymorphisms and obesity, but the observations have been discordant. This paper will discuss the current topics involving the influence of the sympathetic nervous system and β2- and β3-adrenoceptor polymorphisms in obesity.

Roles of beta2- and beta3-adrenoceptor polymorphisms in hypertension and metabolic syndrome

Hypertension, diabetes mellitus (especially type 2 diabetes mellitus), metabolic syndrome and obesity are rapidly growing public health problems. Sympathetic nerve activation is observed in obesity, hypertension and diabetes mellitus, which have strong genetic as well as environmental determinants. Reduced energy expenditure and resting metabolic rate are predictive of weight gain, and the sympathetic nervous system participates in regulating energy balance through thermogenesis. The thermogenic effects of catecholamines in obesity have been mainly mediated via the β2- and β3-adrenergic receptors in humans. Further, β2-adrenoceptors importantly influence vascular reactivity and may regulate blood pressure. Genetic polymorphistns of the β-adrenoceptor gene have been shown to alter the function of several adrenoceptor subtypes and thus to modify the response to catecholamine. β2-adrenoceptor polymorphisms (Arg16Gly, Gln27Glu, and Thr164Ile) have been studied in relation to hypertension. Genetic variations in the β3-adrenoceptor (i.e. Try64Arg variant) are also associated with both obesity and hypertension. However, the precise relationships of the polymorphisms of β2- and β3-adrenoceptor genes with sympathetic nervous system activity, hypertension, and metabolic syndrome have not been fully clarified. This paper will discuss the current topics involving the influence of the sympathetic nervous system and β2- and β3- adrenoceptor polymorphisms in hypertension and metabolic syndrome.

Recent progress in the genetics of common obesity

The genetic contribution to interindividual variation in common obesity has been estimated at 40-70%. Yet, despite a relatively high heritability, the search for obesity susceptibility genes has been an arduous task. This paper reviews recent progress made in the obesity genetics field with an emphasis on established obesity susceptibility loci identified through candidate gene as well as genome-wide studies. For the last 15 years, candidate gene and genome-wide linkage studies have been the two main genetic epidemiological approaches to identify genetic loci for common traits, yet progress has been slow and success limited. Only recently have candidate gene studies started to succeed; by means of large-scale studies and meta-analyses at least five variants in four candidate genes have been found to be robustly associated with obesity-related traits. Genome-wide linkage studies, however, have so far not been able to pinpoint genetic loci for common obesity. The genome-wide association approach, which has become available in recent years, has dramatically changed the pace of gene discoveries for common disease, including obesity. Three waves of large-scale high-density genome-wide association studies have already discovered at least 15 previously unanticipated genetic loci incontrovertibly associated with body mass index and extreme obesity risk. Although the combined contribution of these loci to the variation in obesity risk at the population level is small and their predictive value is typically low, these recently discovered loci are set to improve fundamentally our insights into the pathophysiology of obesity.

Diabesity: therapeutic options

A pathogenic relationship exists between type 2 diabetes and obesity. Over the last decade, the escalation in diabetes cases has paralleled the rapid increase in obesity rates, constituting a global health crisis. Environmental risk factors attributed to the global increase in obesity include the consumption of high-calorie, high-fat foods and inadequate physical activity. Obese individuals may also have a genetic predisposition for obesity. Both diabetes and obesity confer an elevated risk of developing a range of complications and comorbidities, including cardiovascular disease, hypertension and stroke, which can complicate disease management. This review examines the aetiology of the linkages between diabetes and obesity and the range of available therapies. Recent clinical evidence substantiating the efficacy and safety of incretin-based antidiabetic therapies is analysed, in addition to data on antiobesity therapeutic strategies, such as antiobesity agents, behaviour modification and bariatric surgery. Glucose control is often accompanied by weight-neutral or modest weight reduction effects with DPP-4 inhibitor treatment (sitagliptin, vildagliptin, saxagliptin) and weight loss with GLP-1 receptor agonist therapy (exenatide, liraglutide). Studies of antiobesity agents including orlistat, sibutramine and rimonabant have shown attrition rates of 30-40%, and the long-term effects of these agents remain unknown. Bariatric surgical procedures commonly performed are laparoscopic adjustable banding of the stomach and the Roux-en-Y gastric bypass, and have produced type 2 diabetes remission rates of up to 73%. Therapeutic strategies that integrate glycaemic control and weight loss will assume greater importance as the prevalence of diabetes and obesity increase.

Effect of the β3-adrenergic receptor gene polymorphism Trp64Arg on BMI reduction associated with an exercise-based intervention program in Japanese middle-aged males

OBJECTIVES

The β3-Adrenergic receptor gene polymorphism Trp64Arg (ADRB3 Trp64Arg) may be associated with weight gain, especially in the East Asian populations. To date, however, the results of various investigations aimed at determining whether ADRB3 Trp64Arg has any effect on weight reduction after intervention have been inconsistent. The aim of this study was to assess the effect of ADRB3 Trp64Arg on weight reduction in a non-pharmacological intervention program.

METHODS

Fifty-seven Japanese men (average age 48.1 ± 5.9 years) whose body mass index (BMI) was >23.0 kg/m(2) participated in an intervention program in which they were encouraged to exercise by walking with a pedometer for 12 weeks. The BMI was measured at the start of the intervention program and on weeks 4, 8, and 12 (end) of the intervention period. The reduction in the BMI (ΔBMI) was calculated as the BMI value obtained at each point in comparison to the baseline (initial) BMI. The participants were classified into two groups: Arg allele non-carriers (Trp/Trp) and Arg allele carriers (Trp/Arg or Arg/Arg), respectively.

RESULTS

Among the participants, 61.4% were Trp/Trp homozygous, 38.6% were Trp/Arg heterozygous, and 0.0% were Arg/Arg homozygous. There was no significant difference in the ΔBMI between Arg allele non-carriers and Arg allele carriers at week 4 [non-carrier mean ± standard deviation (SD) vs. carrier mean ± SD: 0.25 ± 0.43 vs. 0.24 ± 0.35, respectively; p = 0.954], week 8 (0.56 ± 0.68 vs. 0.58 ± 0.61, respectively; p = 0.913), and week 12 (0.70 ± 0.86 vs. 0.84 ± 0.80, respectively; p = 0.545).

CONCLUSIONS

Our results suggest that ADRB3 Trp64Arg does not influence BMI reduction after an exercise-based intervention program.

No effect of the Trp64Arg variant of the beta3-adrenergic receptor gene on weight loss by diet and exercise intervention among Japanese adults

Controversy remains as to whether the presence of the tryptophan-to-arginine (Trp64Arg) variant of the beta(3)-adrenergic receptor gene impedes the magnitude of body weight loss by diet and exercise intervention. The objectives of the present study were to compare the changes in body weight between carriers and noncarriers of the Trp64Arg variant before and after 6 months of diet and exercise interventions for weight loss. A total of 37 middle-aged Japanese individuals (12 carriers and 25 noncarriers of the Trp64Arg variant) participated in the study. There were no significant differences in body weight between the 2 groups at the baseline. There were significant reductions in body weight both in carriers and noncarriers, but no significant differences between the 2 groups with respect to changes in these variables. The weight changes were -2.52 kg (95% confidence interval [CI], -3.56 to -1.48) among carriers and -1.89 kg (95% CI, -2.65 to -1.13) among noncarriers, and the change in the variant carrier group minus the change in the variant noncarrier group was -0.47 (95% CI, -1.97 to 1.02). These results suggest that the presence of the Trp64Arg variant of the beta(3)-adrenergic receptor gene may not play a major role as a hindrance to weight reduction.

Genetic polymorphisms differently influencing the emergence of atrophy and fat accumulation in HIV-related lipodystrophy

OBJECTIVE AND DESIGN

The present study aims at evaluating the influence of genetic polymorphisms on antiretroviral therapy (ART)-associated lipodystrophy. We included in the study 255 ICoNA. patients and we assessed the distribution of Fas -670 AG polymorphism, ApoC3 -455 CT and -482 CT polymorphisms, C161T silent substitution in the PPAR gamma gene, the Adrenergic beta3 Receptor (ARbeta3) codon 64 TC variant, and two polymorphisms in the Adrenergic beta2 Receptor (ARbeta2) codon 16 AG and codon 27 CG. Crude rates of lipoatrophy and fat accumulation and adjusted relative rates were calculated using Poisson regression.

RESULTS

In a multivariate model after adjusting for gender, HIV exposure, age, current viral load, hepatitis C virus (HCV) serology, nucleoside reverse-transcriptase inhibitor (NRTI) pair/'third drugs' currently used, months of pre-highly active antiretroviral therapy (HAART) exposures to NRTI, the following genotypes resulted protective against lipoatrophy: ApoC3 -455 CC genotype [adjusted relative risks (ARR) 0.2, 95% confidence interval (CI) 0.046-0.91 vs CT/TT, P = 0.037], ARbeta3 codon 64 TT genotype (ARR 0.39, 95% CI 0.14-1.06 vs TC/CC, P = 0.066), and Fas -670 GG genotype (ARR 0.51, 95% CI 0.26-1.01 vs AG/AA, P = 0.053). With regard to fat accumulation, in the multivariate model, the ARbeta2 codon 27 CC genotype resulted protective (ARR 0.21, 95% CI 0.08-0.51 vs CG/GG, P = 0.0006), whereas the ARbeta2 codon 16 AA genotype resulted associated with higher risk (ARR 3.72, 95% CI 1.58-8.76 vs AG/GG, P = 0.0026).

CONCLUSION

Our study suggests that genetic polymorphisms of genes involved in apoptosis and adipocyte metabolism are significantly related to ART associated lipodystrophy. Particularly, we evidenced a role for ApoC3 -455 in lipoatrophy and for the two variants of ARbeta2 in fat accumulation.

The discovery of drugs for obesity, the metabolic effects of leptin and variable receptor pharmacology: perspectives from beta3-adrenoceptor agonists

Although beta3-adrenoceptor (beta3AR) agonists have not become drugs for the treatment of obesity or diabetes, they offer perspectives on obesity drug discovery, the physiology of energy expenditure and receptor pharmacology. beta3AR agonists, some of which also stimulate other betaARs in humans, selectively stimulate fat oxidation in rodents and humans. This appears to be why they improve insulin sensitivity and reduce body fat whilst preserving lean body mass. Regulatory authorities ask that novel anti-obesity drugs improve insulin sensitivity and reduce mainly body fat. Drugs that act on different targets to stimulate fat oxidation may also offer these benefits. Stimulation of energy expenditure may be easy to detect only when the sympathetic nervous system is activated. Leptin resembles beta3AR agonists in that it increases fat oxidation, energy expenditure and insulin sensitivity. This is partly because it raises sympathetic activity, but it may also promote fat oxidation by directly stimulating muscle leptin receptors. The beta1AR and beta2AR can, like the beta3AR, display atypical pharmacologies. Moreover, the beta3AR can display variable pharmacologies of its own, depending on the radioligand used in binding studies or the functional response measured. Studies on the beta3AR demonstrate both the difficulties of predicting the in vivo effects of agonist drugs from in vitro data and that there may be opportunities for identifying drugs that act at a single receptor but have different profiles in vivo.

Association of FTO with obesity-related traits in the Cebu Longitudinal Health and Nutrition Survey (CLHNS) Cohort

OBJECTIVE

The underlying genetic component of obesity-related traits is not well understood, and there is limited evidence to support genetic association shared across multiple studies, populations, and environmental contexts. The present study investigated the association between candidate variants and obesity-related traits in a sample of 1,886 adult Filipino women from the Cebu Longitudinal Health and Nutrition Survey (CLHNS) cohort.

RESEARCH DESIGN AND METHODS

We selected and genotyped 19 single nucleotide polymorphisms in 10 genes (ADRB2, ADRB3, FTO, GNB3, INSIG2, LEPR, PPARG, TNF, UCP2, and UCP3) that had been previously reported to be associated with an obesity-related quantitative trait.

RESULTS

We observed evidence for association of the A allele of rs9939609 (FTO intron 1) with increased BMI (P = 0.0072 before multiple test correction), baseline BMI (P = 0.0015), longitudinal BMI based on eight surveys from 1983 to 2005 (P = 0.000029), waist circumference (P = 0.0094), and weight (P = 0.021). The increase in average BMI was approximately 0.4 for each additional A allele. We also observed association of the ADRB3 Trp64Arg variant with BMI, waist circumference, percent body fat, weight, fat mass, arm fat area, and arm muscle area (P < 0.05), although the direction of effect is inconsistent with the majority of previous reports.

CONCLUSIONS

Our study confirms that FTO is a common obesity susceptibility gene in Filipinos, with an effect size similar to that seen in samples of European origin.

Association of the beta3-adrenergic receptor Trp64Arg polymorphism with common metabolic traits: studies of 7605 middle-aged white people

AIM/HYPOTHESIS

The functional variant Trp64Arg in the beta(3)-adrenergic receptor has previously been examined for association with obesity and insulin resistance with ambiguous results. For further evaluation the present study examined the impact of the Trp64Arg variant on the pathogenesis of type 2 diabetes and obesity in a relatively large, homogenous study population.

METHODS

The Trp64Arg polymorphism was genotyped in 7605 Danish subjects using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Association was examined in case-control studies of obesity (1529 cases and 6049 controls) and type 2 diabetes (1373 cases and 4742 controls) and quantitative trait analyses among 5822 individuals. Furthermore, the association of Trp64Arg with type 2 diabetes was examined in a meta-analysis.

RESULTS

The Trp64Arg polymorphism was not associated with obesity. However, the Arg-allele was associated with a slightly increased risk of type 2 diabetes (OR1.15 (CI: 1.01-1.31); p=0.04), increased insulin resistance estimated by homeostasis model assessment (p=0.01), higher fasting serum insulin levels (p=0.01), and higher levels of plasma glucose 2-h after glucose ingestion (p=0.02). After sex stratification these associations were only present among women. Furthermore, the Arg-allele was borderline associated with type 2 diabetes in a meta-analysis of the present and 26 previous studies (p=0.06, OR1.27 (CI: 0.99-1.63)) (n=18891).

CONCLUSION/INTERPRETATION

Trp64Arg does not confer an increased risk of obesity among Danes. Yet, in the present study of 7605 Danes the variant is associated with type 2 diabetes and quantitative traits related to type 2 diabetes.

Lack of association of the Trp64Arg polymorphism of beta3-adrenergic receptor gene with energy expenditure in response to caffeine among young healthy women

A close relationship between coffee intake and certain metabolic disorders is known. Caffeine, one of coffee components, can increase energy expenditure (EE), but there are considerable individual differences in the caffeine effects on EE, and the causes have not been fully established in humans. The Arg allele in the beta(3)-adrenergic receptor gene (beta(3)-AR), a marker for obesity-related traits, may be a contributor to individual variations in EE. This study investigated the effect of the Arg allele of beta(3)-AR on caffeine-induced increases in EE. In 44 healthy young women (21 +/- 1 years), physical characteristics, blood pressure, biochemical profiles and dietary nutritional intake were measured. A caffeine-loading test was conducted at a dosage of 4 mg per body weight (kg). EE was measured using an indirect open-circuit calorimeter for a 10-min period before, and at 30 min and 60 min after the caffeine-loading test. The beta(3)-AR Trp64Arg polymorphism was detected with a PCR-restriction fragment length polymorphism method. The frequency of the Arg allele was 24%. The distribution of the Trp/Trp, Trp/Arg, and Arg/Arg genotypes was 58%, 36%, and 6%, respectively. At the baseline, subjects with the Arg/Arg genotype had a significantly lower EE level than those with the Trp/Trp or Trp/Arg genotype. After the caffeine-loading test, there were caffeine-induced increases in EE in all genotypes, but there were no differences in the levels of increase among the genotypes. These findings suggest that the genotypes of beta(3)-AR Trp64Arg polymorphism might be not associated with caffeine-induced increases in EE levels.

Adrenergic beta1 receptor polymorphism (Ser49Gly) is associated with obesity in type II diabetic patients

In the process of lipolysis, adipocytes are stimulated by catecholamines through beta(1), beta(2), and beta(3) adrenergic receptors (ARs). So far, beta(2) and beta(3) AR polymorphisms have been reported related to obesity. However, the relation of beta(1)AR polymorphisms to obesity has not been evaluated. In the present study, we examined whether betaAR polymorphisms are associated with obesity-related phenotype in type II diabetic patients. Polymorphisms of beta(1)Ser49Gly, beta(1)Arg389Gly, beta(2)Arg16Gly, beta(2)Gln27Glu and beta(3)Trp64Arg were genotyped in 188 type II diabetic patients by PCR-RFLP. Among these polymorphisms, beta(1)Ser49Gly was found to be associated with obesity. Subjects with beta(1)Gly49 allele showed higher body mass index (BMI) than those with Ser49/Ser49 genotype (24.7+/-3.7 vs. 23.4+/-3.3 kg/m(2); p=0.031). Subjects with beta(1)Gly49 allele were more frequently overweight (BMI >or= 25 kg/m(2)) compared with beta(1)Ser49 homozygous group (42.1 vs. 24.4%, p=0.015). By multiple linear regression analysis, beta(1)Ser49Gly polymorphism was independently associated with higher BMI (p=0.019, beta=0.166). Our data indicate that the Gly49 allele in beta(1)AR is associated with higher BMI in type II diabetic patients. Genotyping for beta(1)Ser49Gly polymorphism in type II diabetic patients may have clinical benefit to predict obesity, thereby contributing to the prevention of insulin resistance.

beta(3)-adrenergic receptor polymorphism and metabolic syndrome in postmenopausal women

OBJECTIVES

Some studies indicate that the Trp64Arg polymorphism in the gene encoding the beta(3)-adrenergic receptor (ADRB3) is associated with obesity, insulin resistance and earlier onset of type 2 diabetes mellitus. The aim of the present study was to evaluate the frequency of ADRB3 polymorphism and its association with metabolic syndrome in postmenopausal women.

METHODS

We performed the study on 284 randomly chosen postmenopausal women, aged 50-60 years, who were then selected to the study. Measurements of anthropometric parameters and biochemical estimations such as lipid profile, glucose and insulin level in serum were carried out using commercial kits. ADRB3 genotyping was performed by polymerase chain reaction and mini-sequencing.

RESULTS

The frequency of the Trp64/Arg64 genotype in the investigated population was 13%, and of the Trp64/Trp64 genotype, 85%. The Arg64/Arg64 genotype was present in only 2% of women. Metabolic syndrome was recognized in 22% of women bearing Trp64/Arg64 genotype and in 14% of women bearing Trp64/Trp64 genotype, without a statistically significant difference between the two groups (p > 0.05 in the chi(2) test). Women bearing the Trp64/Arg64 genotype had lower serum levels of high-density lipoprotein cholesterol (HDL-C) than Trp64/Trp64 genotype women (63.2 +/- 13.0 vs. 71.4 +/- 17.4 mg/dl). Both groups did not differ in any other investigated parameter.

CONCLUSION

Trp64Arg polymorphism of the beta(3)-adrenergic receptor gene is not related to metabolic syndrome in postmenopausal Polish women; however, it seems to be associated with decreased HDL-C levels.

Post-exercise oxidative stress and obesity in postmenopausal women: the role of beta3-adrenergic receptor polymorphism

AIM

Some studies indicate that the Trp64Arg polymorphism in the gene encoding the beta3-adrenergic receptor (ADRB3) is associated with obesity, insulin resistance and earlier onset of type 2 diabetes mellitus. The aim of the present study was to evaluate the frequency of this polymorphism and its relationship with obesity and oxidative stress in postmenopausal women.

MATERIAL AND METHODS

We performed the study on 200 women, aged 50-60 years. Estimation of anthropometric parameters and total body fat, android and gynoid fat deposits was carried out using dual-energy X-ray absorptiometry. Oxidative stress was estimated by measurement of thiobarbituric acid-reactive substances (TBARS) in serum. Blood for analysis was collected before, directly after and 6 h after a 30-min physical test on a cycle ergometer. ADRB3 genotyping was performed by polymerase chain reaction.

RESULTS

The frequency of Trp64/Arg64 genotype in the investigated population was 12%, and of Trp64/Trp64 was 87%. The Arg64/Arg64 genotype was present in only 1% of women. Women bearing the Trp64/Arg64 genotype did not differ in any measured anthropometric parameters from women bearing the Trp64/Trp64 genotype. Moreover, genotype had no influence on oxidative stress parameters. Likewise, in both groups, mean plasma level of TBARS was increased significantly (p < 0.05) directly after the endurance test and remained elevated 6 h after the test.

CONCLUSIONS

The Trp64Arg polymorphism of ADRB3 seems to not be related to obesity in postmenopausal women. Moreover, the Trp64Arg polymorphism has no influence on oxidative stress intensification after standardized physical effort in postmenopausal women.

Metabolic syndrome and ADRB3 gene polymorphism in severely obese patients from South Italy

OBJECTIVE

To evaluate the prevalence of beta(3)-adrenergic receptor (ADRB3) Trp64Arg polymorphism and its relationship with the metabolic syndrome in severe obesity.

DESIGN

Cross-sectional outpatients study.

PATIENTS AND METHODS

In 265 (100 men) severely obese non-diabetic subjects and 78 (25 men) healthy volunteers, genomic DNA was isolated from peripheral leukocytes. In obese patients, plasma concentrations of leptin, lipids, glucose and insulin, the homeostasis model assessment index and blood pressure have been measured. The Trp64Arg mutation was identified with the real-time TaqMan method.

RESULTS

Neither genotype distribution nor allele frequency differed between the two groups. The metabolic syndrome prevalence was 59% in obese subjects, and was higher in men than in women (65 vs 55%: P=0.03). The body mass index (BMI) was related to age tertiles (beta=0.08; P<0.001; multiple linear regression) in Trp64Arg-positive obese subjects.

CONCLUSION

We confirm the high prevalence of the metabolic syndrome among severely obese subjects. ADRB3 polymorphism was significantly related to insulin resistance only in obese male subjects. Moreover, increased BMI was related to age in obese subjects with the ADRB3 polymorphism.

beta2- and beta3-Adrenoceptor polymorphisms relate to subsequent weight gain and blood pressure elevation in obese normotensive individuals

High blood pressure (BP) is a major determinant of cardiovascular events in obesity. The beta2- and beta3-adrenoceptor polymorphisms are associated with obesity and hypertension. In the present study, we examine the relationships of beta2- and beta3-adrenoceptor polymorphisms with further weight gain-induced BP elevation in obese subjects. Changes in BP, body weight, total body fat-mass, waist-to-hip ratio, plasma norepinephrine (NE) and leptin levels, and beta2(Arg16Gly)- and beta3(Trp64Arg)-adrenoceptor polymorphisms were measured periodically over a 5-year period in 55 entry obese (body mass index [BMI]> or =25.0 kg/m(2)) normotensive (BP<140/90 mmHg) men. BP elevation and weight gain were defined as > or =10% increases from entry levels over 5 years in mean BP or BMI. Obese subjects with weight gain, BP elevation or weight gain-induced BP elevation had higher frequencies of the Gly16 allele of Arg16GIy and Arg64 allele of Trp64Arg. Subjects carrying the Gly16 or Arg64 alleles had significantly greater total fat-mass and waist-to-hip ratio at entry and over a 5-year period compared to the subjects who did not carry these polymorphisms. Subjects carrying the Gly16 allele had similar levels of plasma NE, higher levels of plasma leptin and a lower slope of the regression lines between plasma leptin and NE levels. Those carrying the Arg64 allele had higher plasma NE levels at entry and over a 5-year period compared to the subjects without the Arg64 allele, but plasma leptin levels and slopes were similar. The findings demonstrate that the Arg64 allele of the beta3-adrenoceptor polymorphisms relates to weight gain-induced BP elevation accompanying high plasma NE (heightened sympathetic activity) in obese men. The Gly16 allele of the beta2-adrenoceptor polymorphisms links to weight gain-induced BP elevation associated with leptin resistance. beta2- and beta3-adrenoceptor polymorphisms could predict the future BP elevation and further weight gain-induced BP elevation in originally obese subjects.

The association between hyperuricemia and the Trp64Arg polymorphism of the beta-3 adrenergic receptor

The object of this study was to determine the association of Trp64Arg polymorphism with hyperuricemia. This study is an age-matched, case-controlled study of 203 hyperuricemic and 203 normouricemic men. The frequency of genotypes was compared between the two groups. Possible confounding metabolic variables were included in a multiple logistic regression model for multivariate adjustment. The genotype frequencies of Trp64Trp, Trp64Arg, and Arg64Arg in hyperuricemic and normouricemic groups are respectively 130, 69, and 4 (64.0%, 34.0%, 2.0%) and 154, 45, and 4 (75.9%, 22.2%, 2.0%) (P = 0.029, Chi-square test). Simple logistic regression analysis indicated that the Trp64Arg genotype is significantly associated with hyperuricemia (OR = 1.816, 95% CI (1.167-2.827), P = 0.008). Multivariate analysis for controlling metabolic effects also showed a significant association with the occurrence of hyperuricemia (OR = 1.937, 95% CI (1.149-3.266), P = 0.013). Trp64Arg polymorphism of the beta-3 adrenergic receptor may be independently associated with hyperuricemia in males.

Adrenergic receptor polymorphisms and autonomic nervous system function in human obesity

Adrenergic receptors (ARs) are cell-surface G-protein-coupled receptors for catecholamines. They are essential components of the sympathetic nervous system, organized within the autonomic nervous system (ANS), which controls various physiological functions, including energy homeostasis and metabolism of glucose and lipids. An impairment of ANS function in metabolism is considered to be one of the pathological states associated with human obesity and related metabolic diseases; thus, alterations in AR function might be implicated in the pathophysiology of these diseases. Several studies have suggested an association between obesity phenotypes and some AR polymorphisms. In vitro and human clinical studies indicate that some of these polymorphisms have functional and pathophysiological significance, including the linkage to ANS function. This review summarizes present knowledge of AR polymorphisms related to human obesity, and their association with ANS function.

Impact of variation in ADRB2, ADRB3, and GNB3 genes on body mass index and waist circumference in a Brazilian population

The potential effect of variants in three catecholaminergic pathway genes (ADRB2, ADRB3, and GNB3) on obesity-related traits was investigated in an European-derived Brazilian population. Three-hundred and thirty-five individuals were screened for the ADRB2 Arg16Gly and Gln27Glu, ADRB3 Trp64Arg, and GNB3 814G-->A and 825C-->T polymorphisms using PCR-based methods. The association of the polymorphisms with quantitative variables was tested separately in each sex by analysis of covariance using general linear models, including age as a covariate. Only the ADRB2 Arg16Gly polymorphism was associated with higher body mass index and waist circumference. This association was restricted to the male sample. As the number of studies increases, it becomes clear that the genetic bases of obesity are complex, with sex-specific effects a playing an important role in its etiology. In the context of this European-derived population, the ADRB2 gene accounts for a significant part of obesity-related phenotypes in males.

Thermogenic responsiveness to nonspecific beta-adrenergic stimulation is not related to genetic variation in codon 16 of the beta2-adrenergic receptor

Stimulation of beta-adrenergic receptors (beta-AR) by the sympathetic nervous system (SNS) modulates energy expenditure (EE), but substantial interindividual variability is observed. We determined whether the thermogenic response to beta-AR stimulation is related to genetic variation in codon 16 of the beta(2)-AR, a biologically important beta-AR polymorphism, and whether differences in SNS activity (i.e., the stimulus for agonist-promoted downregulation) are involved. The increase in EE (DeltaEE, indirect calorimetry, ventilated hood) above resting EE in response to nonspecific beta-AR stimulation [iv isoproterenol: 6, 12, and 24 ng/kg fat-free mass (FFM)/min] was measured in 46 healthy adult humans [Arg16Arg: 9 male, 7 female, 48 +/- 5 yr; Arg16Gly: 11 male, 4 female, 53 +/- 5 yr; Gly16Gly: 3 male, 12 female, 48 +/- 5 yr (means +/- SE)]. Neither FFM-adjusted baseline resting EE (P = 0.83) nor the dose of isoproterenol required to increase EE 10% above resting (P = 0.87) differed among the three groups (Arg16Arg: 5,409 +/- 209 kJ/day, 11.2 +/- 2.1 ng x kg FFM(-1) x min(-1); Arg16Gly: 5,367 +/- 272 kJ/day, 11.1 +/- 2.1 ng x kg FFM(-1) x min(-1); Gly16Gly: 5,305 +/- 159 kJ/day, 10.5 +/- 1.4 ng x kg FFM(-1) x min(-1)). Consistent with this, muscle sympathetic nerve activity and plasma norepinephrine concentrations were not different among the groups. Group differences in sex composition did not influence the results. Our findings indicate that the thermogenic response to nonspecific beta-AR stimulation, an important mechanistic component of overall beta-AR modulation of EE, is not related to this beta(2)-AR polymorphism in healthy humans. This may be explained in part by a lack of association between this gene variant and tonic SNS activity.