Sex differences in environmental and genetic factors for hypertension

BACKGROUND

Sex differences are observed in many aspects of mammalian cardiovascular function and pathology. Hypertension is more common in men than in women of the same age. Although the effects of gonadal hormones on blood pressure are considered contributing factors, the reasons for sex differences in hypertension are still not fully understood. The present study was undertaken to compare the differences in several environmental and genetic factors between men and women in the Hei Yi Zhuang, an isolated subgroup of the Zhuang minority in China.

METHODS

Information on demography, diet, and lifestyle was collected in 835 women and 834 men aged 15 to 84 years. Genotyping of angiotensin-converting enzyme, adrenergic receptor beta(3), aldehyde dehydrogenase 2, calpastatin, connexin 37, hepatic lipase, lipoprotein lipase, peroxisome proliferator-activated receptor gamma, thyrotropin-releasing hormone receptor, and von Willebrand factor also was performed in these subjects.

RESULTS

The levels of systolic and diastolic blood pressure, and the prevalence, awareness, and treatment of hypertension were lower in women than in men (P < .05). Hypertension was positively associated with age, physical activity, alcohol consumption, body mass index, waist circumference, hyperlipidemia, total energy, total fat, sodium intake, and sodium/potassium ratio, and negatively associated with education level, total dietary fiber, potassium intake, angiotensin-converting enzyme, aldehyde dehydrogenase 2, and hepatic lipase genotypes in men (P < .05). Hypertension was positively associated with age, hyperlipidemia, total energy, total fat, sodium intake, sodium/potassium ratio, calpastatin, and von Willebrand factor genotypes, and negatively associated with education level, total dietary fiber, potassium, calcium intake, lipoprotein lipase, and thyrotropin-releasing hormone receptor genotypes in women (P < .05).

CONCLUSION

Sex differences in the prevalence of hypertension in the Hei Yi Zhuang population may be mainly attributed to the differences in dietary habits, lifestyle choices, sodium and potassium intakes, physical activity level, and some genetic polymorphisms.

Association of body mass index and Trp64Arg polymorphism of the beta3-adrenoreceptor gene and leptin level in Tehran Lipid and Glucose Study

In this study the association between beta3-adrenoceptor gene polymorphism and serum concentration of leptin with body mass index (BMI) is investigated. Using subjects in the Tehran Lipid and Glucose Study, genotyping of the Trp64Arg polymorphism of the beta3-adrenoreceptor gene was performed using a restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) technique was used and the association with obesity was investigated. At total of 197 men and 204 women were divided into four groups (BMI<20, 20< or =BMI<25, 25< or =BMI<30, BMI< or =30) and 97, 98, 104 and 102 subjects, respectively, were placed randomly in the four groups. Leptin level was determined by an enzyme immunoassay (EIA) method and FBS, HDL-C, triglyceride and total cholesterol levels were determined by an enzyme colorimetric method. Body mass index (BMI) was also measured. The A (Arg) allele frequency was 0.08 among the population and its presence was significantly associated with increase of leptin level (AA/TA, 30.5+/-24.8 ng/mL; TT, 22.6+/-20.9 ng/mL; P=0.014) but there was no significant association with increased BMI (AA/TA, 27+/-5.6 kg/m2; TT, 25.4+/-5.5 kg/m2; P=0.072). These data show that the presence of the Arg64 allele at the beta3-adenoceptor gene locus is related to increase in leptin level in this population, but is not related to body mass index.

[Influence of angiotensin converting enzyme gene insertion/deletion polymorphism and beta3-adrenergic receptor gene Trp64Arg polymorphism on fetal growth and neonatal insulin sensitivity]

OBJECTIVE

To understand the influence of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and beta3-adrenergic receptor (beta3-AR) gene Trp64Arg polymorphism on fetal growth and neonatal insulin sensitivity.

METHODS

Totally 296 newborn infants were selected into our study and divided into 2 groups according to gestational age and birth weight: adequate-for-gestational-age (AGA) group (222 cases) and small-for-gestational-age (SGA) group (74 case). Serum glucose and insulin were examined in the morning of the 3rd day before milk. Insulin sensitivity was evaluated by homeostasis model assessment (HOMA) equation. beta3-AR gene Trp64Arg polymorphism and ACE gene I/D polymorphism (202 cases) were analysed using polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) technique. Gestational age, birth weight, birth weight percentage, serum glucose, insulin and HOMA-IR were compared among different genotype groups. Statistical analysis was performed with the SPSS 10.0 software.

RESULTS

No significant difference was found between the serum glucose level of SGA group (4.03 +/- 1.05 mmol/L) and AGA group (4.05 +/- 1.14 mmol/L), P = 0.008. The serum insulin level (converted into Ln) of SGA group (2.262 +/- 0.746) was significantly higher than that of AGA group (1.757 +/- 0.805), P < 0.001. The HOMA-IR (also converted into Ln) level of SGA group (0.217 +/- 0.367) was also significantly higher than that of AGA group (0.001 +/- 0.378), P < 0.001. In the SGA group beta3-AR gene Arg64 allele carriers had higher serum insulin and HOMA-IR level (both changed to Ln, 2.654 +/- 0.701, 0.371 +/- 0.338) compared with noncarriers (2.074 +/- 0.698, 0.143 +/- 0.360), P < 0.05. The ACE gene DD genotype carriers had higher serum insulin and HOMA-IR level (both were converted into Ln, 2.19 +/- 0.91, 0.51 +/- 1.01) compared with II (1.77 +/- 0.85, 0.02 +/- 0.93) and ID genotype group (1.77 +/- 0.83, 0.05 +/- 0.91), P < 0.05. The ACE gene DD carriers had lower birth weight percentage compared with II and ID genotype group, P < 0.05. When both genes' polymorphisms were taken into account, the newborns who had both DD genotype and Arg64 allele had obviously higher serum insulin level (Ln, 2.560 +/- 1.160) than the neonates who had only one of the polymorphisms mentioned above (1.970 +/- 0.821, 1.992 +/- 0.706) and the neonates who had neither of the two polymorphisms (1.683 +/- 0.832), P < 0.05. The newborns who had both DD genotype and Arg64 allele also had significantly higher HOMA-IR level (Ln, 1.042 +/- 1.315) than the neonates who had only one of the polymorphisms mentioned above (0.247 +/- 0.710, 0.230 +/- 0.890) and the neonates who had neither of the two polymorphisms (-0.053 +/- 0.924), P < 0.05.

CONCLUSION

Newborns SGA had impaired insulin sensitivity. beta3-AR gene Trp64Arg polymorphism and ACE gene I/D polymorphism are important factors that may connect IUGR with insulin resistance syndrome in adulthood.

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.

Long-term hypoxia modulates expression of key genes regulating adipose function in the late-gestation ovine fetus

A major function of abdominal adipose in the newborn is nonshivering thermogenesis. Uncoupling protein (UCP) UCP1 and UCP2 play major roles in thermogenesis. The present study tested the hypothesis that long-term hypoxia (LTH) modulates expression of UCP1 and UCP2, and key genes regulating expression of these genes in the late-gestation ovine fetus. Ewes were maintained at high altitude (3,820 m) from 30 to 138 days gestation (dG); perirenal adipose tissue was collected from LTH and age-matched, normoxic control fetuses at 139-141 dG. Quantitative real-time PCR was used to analyze mRNA for UCP1, UCP2, 11beta hydroxysteroid dehydrogenase type 1 (HSD11B1) and 2 (HSD11B2), glucocorticoid receptor (GR), beta3 adrenergic receptor (beta3AR), deiodinase type 1 (DIO1) and DIO2, peroxisome proliferator activated receptor (PPAR) alpha and gamma and PPARgamma coactivator 1 (PGC1alpha). Concentrations of mRNA for UCP1, HSD11B1, PPARgamma, PGC1, DIO1, and DIO2 were significantly higher in perirenal adipose of LTH compared with control fetuses, while mRNA for HSD11B2, GR, or PPARalpha in perirenal adipose did not differ between control and LTH fetuses. The increased expression of UCP1 is likely an adaptive response to LTH, assuring adequate thermogenesis in the event of birth under oxygen-limiting conditions. Because both glucocorticoids and thyroid hormone regulate UCP1 expression, the increase in HSD11B1, DIO1, and DIO2 implicate increased adipose capacity for local synthesis of these hormones. PPARgamma and its coactivator may provide an underlying mechanism via which LTH alters development of the fetal adipocyte. These findings have important implications regarding fetal/neonatal adipose tissue function in response to LTH.

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.

Expression and functional role of beta-adrenoceptors in the human urinary bladder urothelium

We investigated the presence of beta-adrenoceptor subtypes in human urinary bladder urothelium and examined whether beta-adrenoceptors in the urothelium modulate the relaxation responses of isolated human detrusor strips to a beta-adrenoceptor agonist. Expression of beta1-, beta2-, and beta3-adrenoceptor mRNA in urothelium and detrusor smooth muscle was determined by reverse transcription-polymerase chain reaction, and the distribution of beta1-, beta2-, and beta3-adrenoceptors in human urinary bladder urothelium were examined by immunohistochemistry. Paired human longitudinal detrusor strips with and without an intact urothelium were suspended in organ baths to construct concentration-response curves to isoproterenol. The possible involvement of urothelium-derived nitric oxide (NO) in this response was examined in additional experiments with urothelium-intact strips in the presence of NG-nitro-L-arginine methylester (L-NAME). Results confirmed the expression of beta1-, beta2-, and beta3-adrenoceptors in the human urinary bladder urothelium. Further, the presence of the urothelium caused a parallel rightward shift of the concentration-response curve to isoproterenol with a significant reduction in potency (pEC50). L-NAME failed to exert any significant effect on the relaxation response to isoproterenol in the urothelium-intact strips. These results confirm the presence of beta1-, beta2-, and beta3-adrenoceptors in human urinary bladder urothelium. Further, they suggest that urothelial beta-adrenoceptors induce the release of a urothelium-derived factor which inhibits the beta-adrenoceptor agonist-induced relaxation of the human detrusor smooth muscle and that this inhibitory mechanism might not involve NO.

Association of Trp64Arg polymorphism of beta3-adrenergic receptor with insulin resistance in Polish children with obesity

AIM

To establish the influence of the Trp64Arg variant of the beta3-adrenergic receptor (Trp64Arg- beta3AR) on body mass index (BMI) and insulin resistance (IR) in obese children.

METHODS

BMI, presence of the Trp64Arg mutation, plasma glucose and insulin concentrations during an oral glucose tolerance test (OGTT) and IR were determined in 60 obese and 33 normal weight children.

RESULTS

The frequency of Trp64Arg was similar in normal weight and obese children. BMI, glucose and insulin concentrations during an OGTT in children with Trp64Argbeta3AR were not different from those with Trp64Trpbeta3AR. IR was confirmed in 42.8% of children with Trp64Argbeta3AR and in 45.6% of children with Trp64Trpbeta3AR (NS).

CONCLUSIONS

1. The similar frequency of the Trp64Argbeta3AR variant in normal weight and obese children suggests that it is not a susceptibility gene for obesity in Polish children. 2. The presence of the Trp64Argbeta3AR variant does not have an unfavourable influence on BMI, glucose or insulin concentrations during OGTT or on IR frequency in Polish obese children.

Stimulation of the beta3-Adrenoceptor as a novel treatment strategy for anxiety and depressive disorders

The characterization of the first selective orally active and brain-penetrant beta3-adrenoceptor agonist, SR58611A (amibegron), has opened new possibilities for exploring the involvement of this receptor in stress-related disorders. By using a battery of tests measuring a wide range of anxiety-related behaviors in rodents, including the mouse defense test battery, the elevated plus-maze, social interaction, stress-induced hyperthermia, four-plate, and punished drinking tests, we demonstrated for the first time that the stimulation of the beta3 receptor by SR58611A resulted in robust anxiolytic-like effects, with minimal active doses ranging from 0.3 to 10 mg/kg p.o., depending on the procedure. These effects paralleled those obtained with the prototypical benzodiazepine anxiolytic diazepam or chlordiazepoxide. Moreover, when SR58611A was tested in acute or chronic models of depression in rodents, such as the forced-swimming and the chronic mild stress tests, it produced antidepressant-like effects, which were comparable in terms of the magnitude of the effects to those of the antidepressant fluoxetine or imipramine. Supporting these behavioral data, SR58611A modified spontaneous sleep parameters in a manner comparable to that observed with fluoxetine. Importantly, SR58611A was devoid of side effects related to cognition (as shown in the Morris water maze and object recognition tasks), motor activity (in the rotarod), alcohol interaction, or physical dependence. Antagonism studies using pharmacological tools targeting a variety of neurotransmitters involved in anxiety and depression and the use of mice lacking the beta3 adrenoceptor suggested that these effects of SR58611A are mediated by beta3 adrenoceptors. Taken as a whole, these findings indicate that the pharmacological stimulation of beta3 adrenoceptors may represent an innovative approach for the treatment of anxiety and depressive disorders.

Effect of the combination of the variants -75G/A APOA1 and Trp64Arg ADRB3 on the risk of type 2 diabetes (DM2)

OBJECTIVE

Numerous genes have been associated with the risk for type 2 diabetes mellitus (DM2). In an attempt to understand how specific variants of different genes interact and intervene in the molecular and physiological mechanisms of disorders such as diabetes or insulin resistance, the search for gene-gene interactions is constantly growing. We searched for a possible interaction between two polymorphisms (Trp64Arg of ADRB3 gene and -75G/A of APOA1gene) and the risk for DM2 in a population from southern Spain.

DESIGN AND METHODS

A cross-sectional study in southern Spain of 1020 people, aged 18-65 years. All persons underwent a clinical, anthropometrical and biochemical evaluation, including an oral glucose tolerance test (OGTT). Insulin resistance was measured by homeostasis model of assessment (HOMA). The polymorphisms -75G/A of APOA1 and Trp64Arg of ADRB3 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and real-time PCR, respectively.

RESULTS

The genotype frequencies of the -75G/A polymorphism of the APOA1 gene were 62.7% GG, 25.7% GA and 11.6% AA, whereas for the Trp64Arg polymorphism of the ADRB3 gene, they were 87.5% Trp/Trp, 11.7% Trp/Arg and 0.8% Arg/Arg. Subjects with both gene variants had a greater odds ratio (OR) of having DM2 [OR = 5.5; 95% confidence interval (CI) = 1.2-23.5] than persons with one or none of the variants, after adjusting for age, sex, body mass index (BMI) and homeostasis model assessment of insulin resistance (HOMA-IR).

CONCLUSIONS

Joint association of allele -75A (APOA1) and allele Arg64 (ADRB3) increase the risk of DM2 in a population from southern Spain.

[The significance of beta-3 adrenergic receptor polymorphism in excessive body gain and obesity development in pregnant women]

The current knowledge allows for the definition of the genetic factors contributing to pathological body mass gain and obesity development. One of the possible candidates is the gene of beta3-adrenergic receptor (ADRB3). Due to the fact that the basic function of this receptor is the induction of thermogenesis process and an increase of energy expenditure, the significance of Trp64Arg polymorphism of ADRB3 gene in disturbances of metabolic processes, which may induce disturbances of adipocytes function and lead to excessive body mass gain, obesity and early beginning of diseases connected with obesity (dyslipidemia, obesity, chronic hypertension, diabetes mellitus type II), has been suggested. The investigations performed in pregnant women concern, in the majority of cases, women with obesity, diabetes mellitus and gestational hypertension. These studies indicate the possible correlation of higher value of body mass index (BMI) with the presence of mutated 64Arg allele. In healthy pregnant women the relationship between Trp64Arg polymorphism of ADRB3 receptor and body gain has been suggested. Additionally, in female carries of the mutated 64Arg allele, a higher placenta mass and birth mass of newborns have been noted. This publication is merely single voice in the discussion because only one cause of excessive body gain and obesity presented here - Trp64Arg polymorphism of ADRB3 receptor. The problem seems to be more complicated and requires an investigation of the influence of other genetic and environmental factors, and the future populate investigations in Trp64Arg polymorphism of ADRB3 receptor.

The Trp64Arg polymorphism of the beta3-adrenergic receptor gene is associated with increased small dense low-density lipoprotein in a rural Japanese population: the Mima study

The presence of small dense low-density lipoprotein (sdLDL) is closely associated with an increased risk of developing coronary artery disease. The Trp64Arg polymorphism of the beta(3)-adrenergic receptor (beta(3)-AR) gene is a genetic marker for obesity-related traits. However, any possible association between this polymorphism and sdLDL profiles is unclear. The objective of this study is to investigate the effects of the polymorphism of the beta(3)-AR gene on LDL particle size and sdLDL in a rural Japanese population. Among 277 subjects, body mass index, blood pressure, fasting serum insulin levels, and insulin resistance index (fasting glucose x fasting insulin/405) were determined. The polymorphism of the beta(3)-AR gene was assessed by polymerase chain reaction-restriction fragment length polymorphism using buccal samples. Low-density lipoprotein particle size and sdLDL were measured with the electrophoretic separation of lipoproteins on the LipoPrint System (Quantimetrix, Redondo Beach, CA). The frequency of the beta(3)-AR allele was 0.19. In Arg carriers (Trp/Arg or Arg/Arg), the mean value of LDL particle size was smaller than that of non-Arg carriers (Trp/Trp) (P < .05). The area percentage of sdLDL was higher in Arg carriers (P < .05) than in non-Arg carriers. A multiple regression analysis showed that the area percentage of sdLDL was correlated with the polymorphism of the beta(3)-AR gene (P < .05), independently of age, sex, body mass index, smoking, and insulin resistance index. The present findings suggest that the beta(3)-AR gene polymorphism plays a role in the genetic predisposition to increased sdLDL, independently of insulin resistance.

β2- and β3-Adrenoceptors activate glucose uptake in chick astrocytes by distinct mechanisms: a mechanism for memory enhancement?

Isoprenaline, acting at beta-adrenoceptors (ARs), enhances memory formation in single trial discriminated avoidance learning in day-old chicks by mechanisms involving alterations in glucose and glycogen metabolism. Earlier studies of memory consolidation in chicks indicated that beta3-ARs enhanced memory by increasing glucose uptake, whereas beta2-ARs enhance memory by increasing glycogenolysis. This study examines the ability of beta-ARs to increase glucose uptake in chick forebrain astrocytes. The beta-AR agonist isoprenaline increased glucose uptake in a concentration-dependent manner, as did insulin. Glucose uptake was increased by the beta2-AR agonist zinterol and the beta3-AR agonist CL316243, but not by the beta1-AR agonist RO363. In chick astrocytes, reverse transcription-polymerase chain reaction studies showed that beta1-, beta2-, and beta3-AR mRNA were present, whereas radioligand-binding studies showed the presence of only beta2- and beta3-ARs. beta-AR or insulin-mediated glucose uptake was inhibited by phosphatidylinositol-3 kinase and protein kinase C inhibitors, suggesting a possible interaction between the beta-AR and insulin pathways. However beta2- and beta3-ARs increase glucose uptake by two different mechanisms: beta2-ARs via a Gs-cAMP-protein kinase A-dependent pathway, while beta3-ARs via interactions with Gi. These results indicate that activation of beta2- and beta3-ARs causes glucose uptake in chick astrocytes by distinct mechanisms, which may be relevant for memory enhancement.

Polymorphism at the ovine β3-adrenergic receptor locus (ADRB3) and its association with lamb mortality1

The beta3-adrenergic receptors (ADRB3) are guanine nucleotide-binding protein (G-protein)-coupled receptors predominantly found on the surface of adipocytes. They are major mediators of the lipolytic and thermogenic effects of high catecholamine concentrations, in particular norepinephrine. Recently, variation in the ovine beta3-adrenergic receptor gene (ADRB3) has been associated with lamb survival in Merino sheep. In this study, PCR-single strand conformational polymorphism analysis of part of the ADRB3 intron was used to genotype 13,420 lambs (Borderdale, n = 351; Corriedale, n = 4,260; Coopworth, n = 1,225; Dorset Down, n = 663; Dorset Down x Coopworth, n = 264; Hampshire, n = 230; Merino, n = 4,488; Merino x Coopworth, n = 329; Merino x Polwarth, n = 226; Polwarth, n = 928; Poll Dorset, n = 241; and Suffolk, n = 215) born on 22 farms throughout the South Island of New Zealand. Univariate and multivariate odds ratios calculated for each of the 8 alleles revealed weak to moderate associations of the A and E alleles with cold survival and alleles C and F with cold-related mortality, and a strong association of the D allele with cold-related mortality and total mortality. This variation at the ADRB3 locus can possibly be exploited as a gene marker to increase selection accuracy when breeding for more cold-tolerant lambs.

Potent oxindole based human β3 adrenergic receptor agonists

The synthesis and biological evaluation of a series of oxindole beta(3) adrenergic receptor agonists is described. A modulation of rat atrial tachycardia was observed with substitution at the 3-position of the oxindole moiety.

Arg64 variant of the beta3-adrenergic receptor is associated with gallstone formation

OBJECTIVES

The beta3-adrenergic receptor (ADRB3) is a transmembrane receptor highly expressed in adipose tissue and thought to be involved in the regulation of lipolysis. ADRB3 is also highly expressed in gallbladder tissue where it may be involved in gallbladder contraction. Because polymorphisms of ADRB3 are present in populations with a high prevalence of gallstones (e.g., Pima-Indians, obese subjects), we hypothesized that known polymorphisms for ADRB3 (Trp64Arg) may represent an independent risk factor for gallstone disease.

METHODS

The EMIL cross-sectional study investigated the health behavior and prevalence of chronic diseases in a small Southwestern German town of 12,475 inhabitants. From 3,893 randomly selected citizens 2,147 subjects were enrolled and screened for gallstones employing ultrasonography. Blood samples were drawn for biochemical analysis and isolation of genomic DNA. ADBR3 genotypes were determined by TaqMan SNP Assay.

RESULTS

We identified 171 (8%) gallstone carriers of whom 143 participated (46 male, 97 female), with a mean age of 51.4, and mean BMI of 29.3 kg/m2. For these subjects an age, gender and BMI matched partner without gallstones was recruited from the study population. Genotyping for ADRB3 revealed an Arg64 allele frequency of 5.9 versus 0.7% (HR = 11.9, P < 0.05) compared with controls.

CONCLUSIONS

Our results indicate that the ADRB3 Trp64Arg polymorphism is associated with gallstone disease thereby representing a genetic marker that identifies subjects at higher risk for gallstone formation.

LEPR p.Q223R, beta3-AR p.W64R and LEP c.-2548G>A gene variants in obese Brazilian subjects

Obesity is due to the combined effects of genes, environment, lifestyle, and the interactions of these factors. The adrenergic receptor beta3 (beta3-AR), leptin (LEP) and leptin receptor (LEPR) genes have been intensively evaluated in the search of variants that could be related to obesity and its cardiometabolic complications. The results of most of these studies have been controversial. In the present study, we investigated the relationship of the beta3-AR p.W64R, LEP c.-2548G>A and LEPR p.Q223R gene variants with body mass index (BMI), in Brazilian subjects of different genetic backgrounds and ethnic origins. Two hundred obese patients (60 males, 140 females, BMI > or = 30 kg/m2) were screened and compared to 150 lean healthy subjects (63 males, 87 females, BMI < or = 24 kg/m2). Genomic DNA was extracted and amplified by polymerase chain reaction. Polymerase chain reaction products were digested with specific restriction enzymes and separated by electrophoresis. There was no significant difference in the genotype frequency of the beta3-AR p.W64R and the LEP c.-2548G>A polymorphisms, between lean and obese subjects. However, the genotype and allele frequencies of the LEPR p.Q223R variant were significantly different between the normal weight and obese groups. Haplotype analysis has shown an association between the G/G allelic combination of c.-2548G>A LEP and c.668A>G LEPR, in obese subjects. Our results suggest that genetic variability in the leptin receptor is associated with body weight regulation, the LEPR p.Q223R variant being related to BMI increase. The haplotype combination of LEP c.-2548G>A and LEPR p.Q223R variants was related to a 58% increase in obesity risk.

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.

[Metabolic remodeling and the alteration of related receptors expressions in failing heart]

OBJECTIVE

To explore the metabolic remodeling and its correlative mechanisms in human failing heart by contrasting the content of substrate, the activity of correlative enzyme and the mRNA and protein expression of beta(3)-adrenoceptor and peroxisome proliferator-activate receptor alpha (PPARalpha).

METHODS

Cardo ac tossie samples were talem from 20 patients with heart failure of valvular heart disease and undergoing valvuloplasty operation as well as 6 subjects being killed in accidents (as control). The levels of free fat acid (FFA) and the activity of succinate dehydrogenase (SDH), Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase of the myocardial tissue were measured. Protein and mRNA expression of beta(3)-adrenergic receptor and peroxisome proliferator-activated receptor alpha (PPARalpha) in myocardial tissue were analyzed using reverse transcriptase-polymerase chain reaction and Western-blot respectively.

RESULTS

In the failing hearts, the contents of FA and expression of beta 3 adrenoceptor mRNA and protein were obviously higher than those in the control group, the activity of SDH, Na(+)-K(+)-ATPase, Ca(2+)-Mg(2+)-ATPase and expression of PPARalpha mRNA and protein were on the contrary.

CONCLUSION

The human failing myocardium is characterized by metabolic remodeling and it maybe concerned with the upregulation of beta3 adrenoceptor and downregulation of PPARalpha.

beta3-Adrenergic receptor Trp64Arg polymorphism and increased body mass index in sleep apnoea

Obesity is an important risk factor for obstructive sleep apnoea syndrome (OSAS), insulin resistance and cardiovascular disease. The substitution of tryptophan 64 with arginine (Trp64Arg) polymorphism (Arg variant) of the beta(3)-adrenergic receptor (ADRB3) has been associated with obesity. In this study, the prevalence of the Trp64Arg ADRB3 polymorphism in a large group of patients with OSAS and its association with body mass index (BMI), insulin resistance and hypertension were evaluated. ADRB3 genotype was determined in 387 patients with OSAS and 137 healthy subjects recruited from three Spanish tertiary hospitals. The distributions of the ADRB3 genotypes were similar in OSAS and controls, and, in a multivariate model, the risk of OSAS was not associated with the presence of the Arg variant of the ADRB3 gene. However, BMI was higher in those patients with OSAS who carried this genetic variant than in those with the Trp variant. Furthermore, a linear trend for higher BMI was found in those with the Arg variant (56, 75 and 100% for Trp/Trp, Trp/Arg and Arg/Arg, respectively). Insulin resistance, blood pressures and serum levels of lipids and glucose were not associated with the presence of the Arg variant of the ADRB3 gene. The presence of the arginine 64 allele of the beta(3)-adrenergic receptor gene does not increase the risk of obstructive sleep apnoea syndrome, but is associated with the development of obesity in those patients who suffer obstructive sleep apnoea syndrome.

Role of Beta-3-Adrenoceptor in Catecholamine-Induced Relaxations in Gastric Fundus from Control and Diabetic Rats

The contribution of beta-adrenoceptor subtypes to the catecholamine-mediated relaxations in gastric fundus from control and streptozotocin (STZ)-induced diabetic rats were investigated. Isolated organ bath studies and molecular techniques were used to characterize the beta-adrenoceptor subtypes mediating relaxation of rat gastric fundus. Isoprenaline-mediated relaxation was not significantly changed by nadolol (beta(1)-/beta(2)-adrenoceptor antagonist; 1 micromol/l) but only shifted to the right by SR59230A (3-(2-ethylphenoxy)-1-[[(1S)-1,2,3,4-tetrahydronaphth-1-yl]amino]-(2S)-2-propanol oxalate salt, 0.1-1 micromol/l), a selective beta(3)-adrenoceptor antagonist, in a competitive manner. Relaxant responses to noradrenaline were antagonized in a concentration-dependent manner by SR59230A (0.1-1 micromol/l), but not by metoprolol (selective beta(1)-adrenoceptor antagonist; 0.1-1 micromol/l) and ICI-118551 (1-[2,3-(dihydro-7-methyl-1Hinden- 4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride, selective beta(2)-adrenoceptor antagonist; 0.1-1 micromol/l). SR59230A (1 micromol/l) also caused a significant rightward shift in fenoterol-induced relaxation while ICI-118551 (1 micromol/l) did not have any effect. Selective beta(3)-adrenoceptor agonist, BRL37344 ([4-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]amino]propyl]phenoxy]acetic acid), caused biphasic relaxation which was not affected by nadolol (1 micromol/l). SR59230A (1 micromol/l) abolished only the first phase of BRL37344 response. beta(1)-, beta(2)- and beta(3)-adrenoceptor mRNA expressions have been detected in a similar intensity in gastric fundus from control rats. Experimental diabetes caused a significant decrease in E(max) and pD(2) values of isoprenaline and noradrenaline. Diabetes also reduced E(max) but not pD(2) value of the first component of BRL37344-induced relaxation response. The band intensity of mRNA transcript of beta(3)-adrenoceptor was reduced in diabetics while no alteration has been found for beta(1)- and beta(2)-adrenoceptor mRNA transcripts between groups. These results show that functional beta-adrenoceptor subtype involved in catecholamine-mediated relaxations is beta(3)-adrenoceptor, and its function and mRNA expression are decreased in diabetes.

An increase in murine skeletal muscle peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) mRNA in response to exercise is mediated by beta-adrenergic receptor activation

A single bout of exercise increases expression of peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha mRNA, which may promote mitochondrial biogenesis in skeletal muscle. In brown adipose tissue, cold exposure up-regulates PGC-1alpha expression via adrenergic receptor (AR) activation. Because exercise also activates the sympathetic nervous system, we examined whether exercise-induced increase in PGC-1alpha mRNA expression in skeletal muscle was mediated via AR activation. In C57BL/6J mice, injection of the beta2-AR agonist clenbuterol, but not alpha-, beta1-, or beta3-AR agonists, increased PGC-1alpha mRNA expression more than 30-fold in skeletal muscle. The clenbuterol-induced increase in PGC-1alpha mRNA expression in mice was inhibited by pretreatment with the beta-AR antagonist propranolol. In ex vivo experiments, direct exposure of rat epitrochlearis to beta2-AR agonist, but not alpha-, beta1-, and beta3-AR agonist, led to an increase in levels of PGC-1alpha mRNA. Injection of beta2-AR agonist did not increase PGC-1alpha mRNA expression in beta1-, beta2-, and beta3-AR knockout mice (beta-less mice). PGC-1alpha mRNA in gastrocnemius was increased 3.5-fold in response to running on a treadmill for 45 min. The exercise-induced increase in PGC-1alpha mRNA was inhibited by approximately 70% by propranolol or the beta2-AR-specific inhibitor ICI 118,551. The exercise-induced increase in PGC-1alpha mRNA in beta-less mice was also 36% lower than that in wild-type mice. These data indicate that up-regulation of PGC-1alpha expression in skeletal muscle by exercise is mediated, at least in part, by beta-ARs activation. Among ARs, beta2-AR may mediate an increase in PGC-1alpha by exercise.

Ghrelin affects gastrectomy-induced decrease in UCP1 and β3-AR mRNA expression in mice

In this study we investigated the effects of gastrectomy (Gx) and of the gastric hormone, ghrelin, on the expression of proteins in brown adipose tissue (BAT) that are thought to be involved in thermogenesis. Heat production in BAT is known to depend upon activation and increased expression of beta3-adrenergic receptors (beta3-AR) and the consequent up-regulation of uncoupling protein 1 (UCP1). Mice were subjected to Gx or sham operation. One week later they started to receive daily subcutaneous injections of either saline or ghrelin (12 nmol) for two or eight weeks. Neither Gx nor ghrelin affected daily food intake. Gx did not lower body weight gain (except during the first post-operative week) but Gx mice responded to eight weeks of ghrelin treatment with a greater body weight increase (37%, p<0.05) than saline-injected Gx mice; sham-operated mice did not respond to ghrelin. Gx resulted in a greatly reduced expression of both UCP1 and beta3-AR mRNA in BAT (50% reduction or more, p<0.01) compared to sham-operated mice. Eight weeks of ghrelin treatment raised the UCP1 as well as the beta3-AR mRNA expression in the Gx mice, whereas two weeks of ghrelin treatment decreased UCP1 and beta3-AR mRNA expression compared to Gx mice receiving saline. In fact, mRNA expression in Gx mice after treatment with ghrelin for eight weeks was similar to that in saline-treated sham-operated mice. Ghrelin did not affect UCP1 and beta3-AR mRNA in sham-operated mice neither two nor eight weeks after the operation. The results suggest 1) that signals from the stomach stimulate BAT UCP1 (and possibly thermogenesis) and 2) that ghrelin may contribute to the control of UCP1 expression.

The genetic polymorphisms of beta3-adrenergic receptor (AR) Trp64Arg and beta2-AR Gln27Glu are associated with obesity in Chinese male hypertensive patients

BACKGROUND

Genetic polymorphisms of beta3-adrenergic receptor (AR) Trp64Arg and beta2-AR Gln27Glu may result in significant change in the functions of these receptors. The aims of the present study were to investigate the association between Trp64Arg, Arg16Gly and Gln27Glu polymorphisms and the susceptibility to obesity and hypertension in a Chinese population.

METHODS

A total of 437 Chinese subjects including 149 obese hypertensive patients, 139 non-obese essential hypertensive patients, and 149 non-obese normotensive healthy controls were enrolled in the study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific (AS)-PCR assays were used to identify Trp64Arg, Arg16Gly, and Gln27Glu genotypes.

RESULTS

The allele frequencies of 64Arg and 27Glu in the obese hypertensive group were 0.178 and 0.128, respectively. Both were significantly higher than in the non-obese hypertensive and the control groups (p<0.05). Further analysis showed that this association existed only in male hypertensive patients.

CONCLUSIONS

These data reveal that frequencies of beta3-AR 64Arg and beta2-AR 27Glu were significantly higher in our obese hypertensive patients than in the non-obese hypertensive population and healthy controls. beta3-AR Trp64Arg and beta2-AR Gln27Glu genetic polymorphisms are associated with obesity in Chinese male hypertensive patients.