Autonomic Nervous System Pharmacogenomics: A Progress Report

Development of the cardioprotective drugs class based on pathophysiology of myocardial infarction: A comprehensive review

The cardiovascular system is mainly responsible for the transport of substances necessary to cellular metabolism. However, for the good performance of this function, there is need for adequate control of blood pressure levels of tissue perfusion and systemic arterial. Acute myocardial infarction is one of the complications of the cardiovascular system, that most affects the population around the world. This condition can be defined as a disease generated by an imbalance of oxygen concentrations used in cardiovascular metabolism, this change usually occurs because coronary occlusion, which prevents myocardial blood flow. The diagnosis is based on the set of clinical and laboratory investigations, which are in the release of cardiac enzyme biomarkers, cardiovascular and hemodynamic changes and cardiac accommodations. The treatment consists in the use of concomitant cardiovascular drugs, such as: antihypertensive, antiplatelet and hypolipidemic. Despite improvements in clinical and pharmacological management, acute myocardial infarction remains the leading cause of death worldwide. This finding encourages the scientific research of new drugs for the treatment of myocardial infarction or supporting therapies aimed at reducing the levels of deaths and comorbities generated by cardiovascular diseases.

Role of Noradrenaline and Adrenoreceptors in Regulating Prostaglandin E2 Synthesis Cascade in Inflamed Endometrium of Pigs

In the inflamed uterus, the production and secretion of prostaglandins (PGs) and noradrenergic innervation pattern are changed. Receptor-based control of prostaglandin E2 (PGE2) production and secretion by noradrenaline during uterine inflammation is unknown. The aim of this study was to determine the role of α1-, α2- and β-adrenoreceptors (ARs) in noradrenaline-influenced PG-endoperoxidase synthase-2 (PTGS-2) and microsomal PTGE synthase-1 (mPTGES-1) protein levels in the inflamed pig endometrium, and in the secretion of PGE2 from this tissue. E. coli suspension (E. coli group) or saline (CON group) was injected into the uterine horns. Eight days later, severe acute endometritis developed in the E. coli group. Endometrial explants were incubated with noradrenaline and/or α1-, α2- and β-AR antagonists. In the CON group, noradrenaline did not significantly change PTGS-2 and mPTGES-1 protein expression and increased PGE2 secretion compared to the control values (untreated tissue). In the E. coli group, both enzyme expression and PGE2 release were stimulated by noradrenaline, and these values were higher versus the CON group. The antagonists of α1- and α2-AR isoforms and β-AR subtypes do not significantly alter the noradrenaline effect on PTGS-2 and mPTGES-1 protein levels in the CON group, compared to noradrenaline action alone. In this group, α1A-, α2B- and β2-AR antagonists partly eliminated noradrenaline-stimulated PGE2 release. Compared to the noradrenaline effect alone, α1A-, α1B-, α2A-, α2B-, β1-, β2- and β3-AR antagonists together with noradrenaline reduced PTGS-2 protein expression in the E. coli group. Such effects were also exerted in this group by α1A-, α1D-, α2A-, β2- and β3-AR antagonists with noradrenaline on mPTGES-1 protein levels. In the E. coli group, the antagonists of all isoforms of α1-ARs and subtypes of β-ARs as well as α2A-ARs together with noradrenaline decreased PGE2 secretion versus noradrenaline action alone. Summarizing, in the inflamed pig endometrium, α1(A, B)-, α2(A, B)- and β(1, 2, 3)-ARs mediate the noradrenaline stimulatory effect on PTGE-2 protein expression, while noradrenaline via α1(A, D)-, α2A- and β(2, 3)-ARs increases mPTGES-1 protein expression and α1(A, B, D)-, α2A- and β(1, 2, 3)-ARs are involved in PGE2 release. Data suggest that noradrenaline may indirectly affect the processes regulated by PGE2 by influencing its production. Pharmacological modulation of particular AR isoforms/subtypes can be used to change PGE2 synthesis/secretion to alleviate inflammation and improve uterine function.

Effect of blocking of alpha1-adrenoreceptor isoforms on the noradrenaline-induced changes in contractility of inflamed pig uterus

BACKGROUND

Disturbances in uterine contractility often lead to the origin, development and maintenance of endometritis and metritis, which are a very common and serious pathologies in domestic animals. Here we aimed to investigate the role of α1A-, α1B- and α1D-adrenoreceptors (ARs) in noradrenaline (NA)-induced contractility of inflammatory-changed porcine uterus.

METHODS

On Day 3 of the estrous cycle, either Escherichia coli (E. coli) suspension (E. coli group) or saline (SAL group) was injected into uterine horns, or only laparotomy was performed (CON group). Eight days later, infected gilts developed severe acute endometritis.

RESULTS

Compared to the period before NA application, NA reduced the contractile amplitude and frequency in myometrium (MYO) and endometrium (ENDO)/MYO strips from the CON, SAL and E. coli groups. In the last group, the amplitude in MYO and the frequency in ENDO/MYO were lowered versus other groups. After using α1A-ARs antagonist with NA, a greater decrease or occurrence of a drop in the amplitude and frequency in all groups (ENDO/MYO) were found compared to this neurotransmitter action alone. Such results were noted for NA action on the frequency after α1B-ARs blocking in the CON (both kinds of strips) and SAL (ENDO/MYO) groups. In response to α1D-ARs antagonist with NA, a greater decrease or occurrence of a drop in the amplitude was noted in the CON (both kinds of strips) and SAL and E. coli (MYO) groups. Use of these factors caused the similar changes in the frequency in CON and E. coli (MYO) and SAL (ENDO/MYO) groups. In response to NA, α1A,B,D-ARs antagonist led to a greater reduction or appearance of a drop in the amplitude in the CON and SAL (ENDO/MYO) and E. coli (both kinds of strips) as well as in the frequency in the CON and SAL (ENDO/MYO) and E. coli (MYO) groups.

CONCLUSIONS

In conclusion, activation of α1A- and α1D-ARs by NA promotes the contractile amplitude and frequency in the inflamed pig uterus; pharmacological modulation of these receptors can be utilized to enhance systolic activity of myometrium.

Interactions between the Autonomic Nervous System and the Immune System after Stroke

Acute stroke is one of the leading causes of morbidity and mortality worldwide. Stroke-induced immune-inflammatory response occurs in the perilesion areas and the periphery. Although stroke-induced immunosuppression may alleviate brain injury, it hinders brain repair as the immune-inflammatory response plays a bidirectional role after acute stroke. Furthermore, suppression of the systemic immune-inflammatory response increases the risk of life-threatening systemic bacterial infections after acute stroke. Therefore, it is essential to explore the mechanisms that underlie the stroke-induced immune-inflammatory response. Autonomic nervous system (ANS) activation is critical for regulating the local and systemic immune-inflammatory responses and may influence the prognosis of acute stroke. We review the changes in the sympathetic and parasympathetic nervous systems and their influence on the immune-inflammatory response after stroke. Importantly, this article summarizes the mechanisms on how ANS regulates the immune-inflammatory response through neurotransmitters and their receptors in immunocytes and immune organs after stroke. To facilitate translational research, we also discuss the promising therapeutic approaches modulating the activation of the ANS or the immune-inflammatory response to promote neurologic recovery after stroke. © 2022 American Physiological Society. Compr Physiol 12:3665-3704, 2022.

Role of β3-Adrenergic Receptor in Bone Marrow Transplant as Therapeutical Support in Cancer

β3-adrenergic receptor (β3-AR) is the last β-adrenoceptor subtype identified. β3-AR is widely expressed and regulates numerous physiological processes, and it is also a potential target for the treatment of many diseases, including cancers. For some types of cancers, bone marrow transplant (BMT) represents a valid therapeutic support, especially in the case of the necessity of high-dose chemotherapy and radiotherapy. For a successful BMT, it is necessary that a donor’s hematopoietic stem cells (HSCs) correctly reach the staminal niche in the recipient’s bone marrow (BM) and contribute to restore normal hematopoiesis in order to rapidly repopulate BM and provide all the healthy blood cells of which the patient needs. Generally, it takes a long time. Control and accelerate homing and engraftment of HSCs could represent a helpful approach to avoid the complications and undesirable effects of BMT. The evidence that the β-adrenergic system has a role in the BM can be found in different studies, and this leads us to hypothesize that studying this field could be interesting to meliorate the most critical aspects of a BMT. Here, we collected the data present in literature about the role of β3-AR in the BM with the purpose of discovering a possible utility of β3-AR modulation in regulating HSC trafficking and hematopoiesis.

Psychophysiological dynamics of emotional reactivity: Interindividual reactivity characterization and prediction by a machine learning approach

The fast reaction of the autonomic nervous system (ANS) to an emotional challenge (EC) is the result of a functional coupling between parasympathetic (PNS) and sympathetic (SNS) branches. This coupling can be characterized by measures of cross-correlations between electrodermal activity (EDA) (under the influence of the SNS) and the RR interval (the interval between R peaks) (under the influence of the PNS and the SNS). Significant interindividual variability has previously been reported in SNS-PNS coupling in emotional situations, and the present study aimed to identify interindividual cross-correlation variability in ANS reactivity. We therefore studied EDA and the RR interval in 62 healthy subjects, recorded during a 24-minute EC. A Gaussian Mixture Model was used to cluster tonic EDA-RR cross-correlations during the EC. This identified two clusters that were characterized by significant or non-significant cross-correlations (SCC and NCC clusters, respectively). The SCC cluster reported higher negative emotion after the EC, while the NCC cluster reported higher scores on the Center for Epidemiologic Studies-Depression scale. The latter finding suggests that NCC is a pathological mood pattern with altered negative perception. Furthermore, a machine learning model that included three parameters indexing the functionality of both branches of the ANS, measured at baseline, predicted cluster membership. Our results are a first step in detecting dysfunctional ANS reactivity in general population.

Role of beta-adrenergic receptor subtypes in pig uterus contractility with inflammation

Uterine inflammation is a very common and serious condition in domestic animals. To development and progression of this pathology often lead disturbances in myometrial contractility. Participation of β1-, β2- and β3-adrenergic receptors (ARs) in noradrenaline (NA)-influenced contractility of the pig inflamed uterus was studied. The gilts of SAL- and E.coli-treated groups were administered saline or E.coli suspension into the uterine horns, respectively. Laparotomy was only done in the CON group. Compared to the period before NA administration, this neurotransmitter reduced the tension, amplitude and frequency in uterine strips of the CON and SAL groups. In the E.coli group, NA decreased the amplitude and frequency, and these parameters were lower than in other groups. In the CON, SAL and E.coli groups, β1- and β3-ARs antagonists in more cases did not significantly change and partly eliminated NA inhibitory effect on amplitude and frequency, as compared to NA action alone. In turn, β2-ARs antagonist completely abolished NA relaxatory effect on these parameters in three groups. Summarizing, NA decreases the contractile amplitude and frequency of pig inflamed uterus via all β-ARs subtypes, however, β2-ARs have the greatest importance. Given this, pharmacological modulation of particular β-ARs subtypes can be used to increase inflamed uterus contractility.

Adrenergic signalling in osteoarthritis

Adrenoceptors (ARs) mediate the effects of the sympathetic neurotransmitters norepinephrine (NE) and epinephrine (E) in the human body and play a central role in physiologic and pathologic processes. Therefore, ARs have long been recognized as targets for therapeutic agents, especially in the field of cardiovascular medicine. During the past decades, the contribution of the sympathetic nervous system (SNS) and particularly of its major peripheral catecholamine NE to the pathogenesis of osteoarthritis (OA) attracted growing interest. OA is the most common degenerative joint disorder worldwide and a disease of the whole joint. It is characterized by progressive degradation of articular cartilage, synovial inflammation, osteophyte formation, and subchondral bone sclerosis mostly resulting in chronic pain. The subchondral bone marrow, the periosteum, the synovium, the vascular meniscus and numerous tendons and ligaments are innervated by tyrosine hydroxylase-positive (TH+) sympathetic nerve fibers that release NE into the synovial fluid and cells of all abovementioned joint tissues express at least one out of nine AR subtypes. During the past decades, several in vitro studies explored the AR-mediated effects of NE on different cell types in the joint. So far, only a few studies used animal OA models to investigate the contribution of distinct AR subtypes to OA pathogenesis in vivo. This narrative review shortly summarizes the current background knowledge about ARs and their signalling pathways at first. In the second part, we focus on recent findings in the field of NE-induced AR-mediated signalling in different joint tissues during OA pathogenesis and at the end, we will delineate the potential of targeting the adrenergic signalling for OA prevention or treatment. We used the PubMed bibliographic database to search for keywords such as 'joint' or 'cartilage' or 'synovium' or 'bone' and 'osteoarthritis' and/or 'trauma' and 'sympathetic nerve fibers' and/or 'norepinephrine' and 'adrenergic receptors / adrenoceptors' as well as 'adrenergic therapy'.

Pharmacogenomics, concepts for the future of perioperative medicine and pain management: A review

Pharmacogenomics is the study of how genetic differences between individuals affect pharmacokinetics and pharmacodynamics. These differences are apparent to clinicians when taking into account the wide range of responses to medications given in clinical practice. A review of literature involving pharmacogenomics and pain management was performed. The implementation of preoperative pharmacogenomics will allow us to better care for our patients by delivering personalized, safer medicine. This review describes the current state of pharmacogenomics as it relates to many aspects of clinical practice and how clinicians can use these tools to improve patient outcomes.

β-Adrenoceptors as drug targets in melanoma: novel preclinical evidence for a role of β3 -adrenoceptors

Stress plays a role in tumourigenesis through catecholamines acting at β-adrenoceptors including β₁ -, β₂ - and β₃ -adrenoceptors, and the use of β-adrenoceptor antagonists seems to counteract tumour growth and progression. Preclinical evidence and meta-analysis data demonstrate that melanoma shows a positive response to β-adrenoceptor blockers and in particular to propranolol acting mainly at β₁ - and β₂ -adrenoceptors. Although evidence suggesting that β₃ -adrenoceptors may play a role as a therapeutic target in infantile haemangiomas has been recently reviewed, a comprehensive analysis of the data available from preclinical studies supporting a possible role of β₃ -adrenoceptors in melanoma was not available. Here, we review data from the literature demonstrating that propranolol may be effective at counteracting melanoma growth, and we provide preclinical evidence that β₃ -adrenoceptors may also play a role in the pathophysiology of melanoma, thus opening the door for further clinical assays trying to explore β₃ -adrenoceptor blockers as novel alternatives for its treatment. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.

Beta 1, Beta 2 and Beta 3 Adrenergic Receptor Gene Polymorphisms in a Southeastern European Population

Genetic polymorphisms in β₁-, β₂- and β₃-adrenergic receptors (β-ARs) have been associated with chronic non-communicable disorders, such as cardiovascular diseases, asthma, chronic obstructive pulmonary disease (COPD) and obesity, as well as β-agonists and antagonists response and toxicity. The purpose of this study was to determine the frequency distribution of ADRB1 genetic variants Ser49Gly and Arg389Gly, ADRB2 variants Gly16Arg and Gln27Glu, ADRB3 variant Trp64Arg in a Southeastern European Caucasian (SEC) population sample and to establish a comparison with existing data from other human populations. A sample of 431 men and 590 women volunteered to participate in this genotyping analysis after anonymization and de-identification. Real Time PCR (Melting Curve Analysis) followed DNA extraction from buccal swabs and statistical analysis of the results was performed. The allele frequencies in the SEC population were Ser49 (90.3%), Arg389 (69.49%), Gly16 (61.61%), Gln27 (65.72%), and Trp64 (94.52%), while a Hardy-Weinberg Equilibrium (HWE) was detected in the population studied. Comparisons for the Ser49Gly, Gln27Glu, and Trp64Arg allele distributions demonstrated significant differences between SEC and the European group. European subgroups comparisons showed that allele distributions were similar for four of the five SNPs between SEC and Southwestern European Caucasians (SWC), while they were quite distinct from the Northwestern European Caucasians (NWC). These data underline the importance of interethnic variability of β-ARs genetic polymorphisms.

The inferior turbinate: An autonomic organ

The inferior turbinate has well-recognized respiratory and immune functions to provide the airway with appropriate warmth, humidification, and filtration of the inspired air while sampling the environment for pathogens. Normal functioning of the inferior turbinate relies on an intact autonomic system to maintain homeostasis within the nasal cavity. The autonomic nervous system innervates the submucosal glands and the vasculature within the inferior turbinate, resulting in control of major turbinate functions: nasal secretions, nasal patency, warmth, and humidification. This review will summarize the autonomic innervations of the turbinates, both the normal and abnormal autonomic processes that contribute to the turbinate functions, and the clinical considerations regarding optimal functioning of the turbinate autonomic system.

Expression of alpha and beta adrenergic receptors in the pig uterus during inflammation

Under physiological conditions, noradrenaline (NA) and adrenergic receptors (ARs) are implicated in the function of the uterus. The role of NA and the expression of ARs in the inflamed uterus is not fully understood. The aim of the present study was to determine the effect of inflammation on the levels of α1 (A, B, D)-, α2 (A, B, C)- and β (1, 2, 3)-ARs mRNA and protein expression and the localization of these receptors in the porcine uterus. On Day 3 of the estrous cycle (Day 0 of the study), 50 ml of either saline (group SAL) or E. coli suspension (10⁹ colony-forming units/ml, group E. coli) were injected into each uterine horn. In the control pigs (group CON), only laparotomy was performed. Eight days later, α1D-ARs mRNA (P < 0.001) and protein (P < 0.05) levels and α2A-ARs protein level (P < 0.05) were increased in the inflamed endometrium, while the α2C-ARs protein level (P < 0.001) was lowered, as compared to the SAL and CON groups. In the inflamed endometrium, β2-ARs mRNA (P < 0.01) and protein (CON: P < 0.01, SAL: P < 0.001) expression was lower than in the other two groups, and β1-ARs mRNA (P < 0.001) and protein (P < 0.01) expression was higher compared to the SAL group. After bacterial treatment, α2A- (P < 0.001) and α2B (P < 0.05) -ARs protein levels and β2-ARs mRNA (CON: P < 0.01, SAL: P < 0.05) and protein (CON: P < 0.01, SAL: P < 0.05) expression in myometrium were found to be increased compared to both groups. In turn, in myometrium following E. coli infusion, the α2C-ARs protein level was lower (P < 0.01) than in the CON group. All studied receptors were present in the luminal and glandular epithelium, blood vessels and myometrial muscular cells of the gilt uteri in the E. coli, SAL and CON groups. The data show that inflammation changes the ARs expression in porcine uterus, suggesting their importance in the course/consequences of uterine inflammation. Those affected ARs may constitute a therapeutic target in an inflamed uterus.

β2‑adrenergic receptor functionality and genotype in two different models of chronic inflammatory disease: Liver cirrhosis and osteoarthritis

The present study was designed to investigate the functional status of β2 adrenoceptors (β2AR) in two models of chronic inflammatory disease: liver cirrhosis (LC) and osteoarthritis (OA). The β2AR gene contains three single nucleotide polymorphisms at amino acid positions 16, 27 and 164. The aim of the present study was to investigate the potential influence of lymphocyte β2AR receptor functionality and genotype in LC and OA patients. Blood samples from cirrhotic patients (n=52, hepatic venous pressure gradient 13±4 mmHg, CHILD 7±2 and MELD 11±4 scores), OA patients (n=30, 84% Kellgren‑Lawrence severity 4 grade, 14% knee replacement joint) and healthy volunteers as control group (n=26) were analyzed. Peripheral blood mononuclear cells (PBMC) were isolated from whole blood and basal and isoproterenol induced adenylate cyclase activity (isoproterenol stimulus from 10‑9 to 10‑4 mM), and β2AR allelic variants (rs1042713, rs1042714, rs1800888) were determined. β2AR functionality was decreased in the two different models of chronic inflammatory disease studied, OA (50% vs. control) and LC (85% vs. control). In these patients, the strength of the β2AR response to adrenergic stimulation was very limited. Adrenergic modulation of PBMC function through the β2AR stimulus is decreased in chronic inflammatory processes including LC and OA, suggesting that the adrenergic system may be important in the development of these processes.

Palmar hyperhidrosis: clinical, pathophysiological, diagnostic and therapeutic aspects

Palmar hyperhidrosis affects up to 3% of the population and inflict significant impact on quality of life. It is characterized by chronic excessive sweating, not related to the necessity of heat loss. It evolves from a localized hyperactivity of the sympathetic autonomic system and can be triggered by stressful events. In this study, the authors discuss clinical findings, pathophysiological, diagnostic and therapeutic issues (clinical and surgical) related to palmar hyperhidrosis.

Alpha2A adrenergic receptor genetic variation contributes to hyperglycemia after myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) is frequently associated with transient hyperglycemia even in patients without pre-existing diabetes. Acute stress can lead to increased blood glucose through the effect of catecholamines on alpha2A-adrenergic receptors (α2A-ARs) present in pancreatic islet β-cells. Variation in the gene (ADRA2A) that encodes the α2A-AR affects insulin release and glucose control and may play a particularly important role during times of stress.

METHODS

We performed a retrospective cohort study using de-identified electronic medical records linked to a DNA repository in 521 Caucasians and 55 African-American non-diabetic patients with AMI. We examined the association between admission blood glucose concentrations and ten selected ADRA2A SNPs in Caucasians.

RESULTS

Three ADRA2A SNPS were associated with stress-induced hyperglycemia in Caucasians. Individuals homozygous for the rs10885122 variant (n=9) had a 23% lower admission glucose (geometric mean [95% CI], 99 [83-118]mg/dl) compared with non-carriers (121 [118-125] mg/dl; n=401; P=0.001). Admission glucose was 14% higher in rs1800544 variant homozygotes (134 [119-150]mg/dl; n=36) compared to non-carriers (118 [115-121]mg/dl; n=290, P=0.046). Furthermore, homozygotes of the rs553668 variant (n=13) had a 13% higher glucose (133 [110-160]mg/dl) compared to non-carriers (118 [115-122]mg/dl; n=366; P=0.056). Haplotypes including these ADRA2A SNPs were associated with higher admission glucose levels.

CONCLUSIONS

Three ADRA2A genetic variants are associated with blood glucose and stress-induced hyperglycemia after AMI in Caucasians.

Immunohistochemical localization of alpha and beta adrenergic receptors in the human nasal turbinate

OBJECTIVE

Adrenergic receptors (ARs) include four general types (α1, α2, β1 and β2), which are found in different target tissues. α-AR agonists are commonly used for decongestant therapy of upper airway diseases. In order to clarify the roles of AR subtypes in the upper airways, we investigated the localization of these receptors by immunohistochemistry.

METHODS

Human turbinates were obtained after turbinectomy from 12 patients with nasal obstruction refractory to medical therapy. The specific cells expressing α- and β-AR proteins were identified by immunostaining using an anti-human AR subtype-specific antibodies (α1A-, α1D-, α2C- and β2-ARs) antibody.

RESULTS

Immunohistochemical analysis revealed that immunoreactivities for α1D- and β2-ARs were densely distributed in submucosal glands. In contrast, immunoreactivities for α1A- and 2C-ARs were densely distributed in vascular smooth muscle.

CONCLUSION

Our results suggested that adrenergic receptor (AR) subtypes had different roles in upper airway diseases, such as allergic rhinitis and nonallergic rhinitis.

The role of stress and beta-adrenergic system in melanoma: current knowledge and possible therapeutic options

PURPOSE

The aim of the present review was to discuss recent findings on the role of beta-adrenergic system in melanoma, in order to provide information on the biological responses elicited by its activation and its potential application for melanoma treatment.

METHODS

A literature search was performed, and evidences regarding the involvement of stress and beta-adrenergic system in cancer and melanoma were found and discussed.

RESULTS

Our search pointed out that beta-adrenergic system is a key regulator of important biological processes involved in the onset and progression of some solid tumors. In the last decade, functional beta-adrenoceptors have been also identified on melanoma cells, as well as on their microenvironment cells. Similarly to other common cancers too, the activation of such adrenoceptors by catecholamines, usually released under stress conditions, has been found to trigger pro-tumorigenic pathways contributing to cell proliferation and motility, immune system regulation, apoptosis, epithelial-mesenchymal transition, invasion and neoangiogenesis.

CONCLUSIONS

The biological evidences we found clarify and sustain the clinical evidences reporting the involvement of chronic stress in melanoma onset and progression. In such scenario, it is conceivable that a therapeutic approach targeting beta-adrenergic system could constitute a novel and promising strategy for melanoma treatment.

Membrane Potential Controls the Efficacy of Catecholamine-induced β1-Adrenoceptor Activity

G protein-coupled receptors (GPCRs) are membrane-located proteins and, therefore, are exposed to changes in membrane potential (V(M)) in excitable tissues. These changes have been shown to alter receptor activation of certain Gi-and Gq-coupled GPCRs. By means of a combination of whole-cell patch-clamp and Förster resonance energy transfer (FRET) in single cells, we demonstrate that the activation of the Gs-coupled β1-adrenoreceptor (β1-AR) by the catecholamines isoprenaline (Iso) and adrenaline (Adr) is regulated by V(M). This voltage-dependence is also transmitted to G protein and arrestin 3 signaling. Voltage-dependence of β2-AR activation, however, was weak compared with β1-AR voltage-dependence. Drug efficacy is a major target of β1-AR voltage-dependence as depolarization attenuated receptor activation, even under saturating concentrations of agonists, with significantly faster kinetics than the deactivation upon agonist withdrawal. Also the efficacy of the endogenous full agonist adrenaline was reduced by depolarization. This is a unique finding since reports of natural full agonists at other voltage-dependent GPCRs only show alterations in affinity during depolarization. Based on a Boltzmann function fit to the relationship of V(M) and receptor-arrestin 3 interaction we determined the voltage-dependence with highest sensitivity in the physiological range of membrane potential. Our data suggest that under physiological conditions voltage regulates the activity of agonist-occupied β1-adrenoceptors on a very fast time scale.

A common hypofunctional genetic variant of GPER is associated with increased blood pressure in women

AIMS

Activation of vascular GPER has been linked to vasodepressor effects in animals. However, the significance of GPER regulation on chronic blood pressure control in humans is unknown.

METHODS

To examine this question we determined the functional significance of expression of a common missense single nucleotide variant of GPER, P16L in vascular smooth muscle cells, and its association with blood pressure in humans. Further, to validate the importance of carrying GPER P16L in the development of hypertension we assessed allele frequency in a cohort of hard-to-treat hypertensive patients referred to a tertiary care clinic.

RESULTS

Expression of the GPER P16L variant (V) vs. wild type (WT) in rat aortic vascular smooth muscle cells, was associated with a significant decrease in G1 (1 μm, a GPER agonist)-mediated ERK phosphorylation (slope of the function of G1-stimulated ERK phosphorylation: GPER content WT: 16.2, 95% CI 9.9, 22.6; V: 5.0, 95% CI 1.0, 9.0; P < 0.005) and apoptosis (slope of the function of G1-stimulated apoptosis: GPER content: WT: 4.4, 95% CI: 3.4, 5.4; V: 2.5, 95% CI 1.6, 2.3 P < 0.005). Normotensive female subjects, but not male subjects, carrying this hypofunctional variant (allele frequency 22%) have increased blood pressure [mean arterial pressure: P16/P16: 80 ± 1 mmHg (n = 204) vs. P16L carriers: 82 ± 1 mmHg (n = 127), 95% CI for difference: 0.6, 4.0 mmHg, P < 0.05], [systolic blood pressure: P16/P16: 105 ± 1 mmHg vs. P16L carriers: 108 ± 1 mmHg, 95% CI for difference:1.0, 5.1 mmHg, P < 0.05], [diastolic blood pressure: P16/P16: 66 ± 0.5 mmHg vs. P16L carriers 68 ± 0.7, 95% CI for difference: 0.2, 3.6 mmHg, P < 0.05]. Further, the P16L allele frequency was almost two-fold higher in female vs. male hypertensive patients (31% vs. 16%, allele ratio 0.5, 95% CI 0.32, 0.76, P < 0.05).

CONCLUSIONS

The common genetic variant, GPER P16L, is hypofunctional and female carriers of this allele have increased blood pressure. There was an increased prevalence in a population of hard-to-treat hypertensive female patients. Cumulatively, these data suggest that in females, impaired GPER function might be associated with increased blood pressure and risk of hypertension.

Interhelical interaction and receptor phosphorylation regulate the activation kinetics of different human β1-adrenoceptor variants

G protein-coupled receptors represent the largest class of drug targets, but genetic variation within G protein-coupled receptors leads to variable drug responses and, thereby, compromises their therapeutic application. One of the most intensely studied examples is a hyperfunctional variant of the human β1-adrenoceptor that carries an arginine at position 389 in helix 8 (Arg-389-ADRB1). However, the mechanism underlying the higher efficacy of the Arg-389 variant remained unclear to date. Despite its hyperfunctionality, we found the Arg-389 variant of ADRB1 to be hyperphosphorylated upon continuous stimulation with norepinephrine compared with the Gly-389 variant. Using ADRB1 sensors to monitor activation kinetics by fluorescence resonance energy transfer, Arg-389-ADRB1 exerted faster activation speed and arrestin recruitment than the Gly-389 variant. Both activation speed and arrestin recruitment depended on phosphorylation of the receptor, as shown by knockdown of G protein-coupled receptor kinases and phosphorylation-deficient ADRB1 mutants. Structural modeling of the human β1-adrenoceptor suggested interaction of the side chain of Arg-389 with opposing amino acid residues in helix 1. Site-directed mutagenesis of Lys-85 and Thr-86 in helix 1 revealed that this interaction indeed determined ADRB1 activation kinetics. Taken together, these findings indicate that differences in interhelical interaction regulate the different activation speed and efficacy of ADRB1 variants.

Intraclass differences among antihypertensive drugs

The four major classes of antihypertensive drugs—diuretics, β-blockers, calcium channel blockers, and renin-angiotensin system inhibitors (including angiotensin-converting enzyme inhibitors and angiotensin receptor blockers)—have significant qualitative and quantitative differences in the adverse effects they cause. Structural and chemical differences have been identified within these classes, especially among the calcium channel blockers and, to a lesser extent, among the thiazide/thiazide-like diuretics. However, it has been more difficult to demonstrate that these differences translate into differential effects with respect to either the surrogate endpoint of blood pressure reduction or, more importantly, hypertension-related cardiovascular complications. Based on a hierarchy-of-evidence approach, differences are apparent between hydrochlorothiazide and chlorthalidone based on evidence of moderate quality. Low-quality evidence suggests atenolol is less effective than other β-blockers. However, no significant intraclass differences have been established among the other classes of antihypertensive drugs.

Administration of an anabolic steroid during the adolescent phase changes the behavior, cardiac autonomic balance and fluid intake in male adult rats

Few data are available on adolescent users because most behavioral studies on anabolic-androgenic steroids (AAS) abuse have been performed in adults. Studies evaluating the impact of long-term effects of AAS abuse on the prepubertal phase are even more uncommon. Accordingly, this study was developed to test the hypothesis that changes induced by the use of AAS during the adolescent phase may be noted in the adult phase even when the AAS treatment cycle is discontinued. Therefore, not only behavioral changes but also possible autonomic and electrolyte disorders were evaluated. For this purpose, we used male prepubertal, 26-day-old (P26) Wistar rats that were treated with vehicle (control, n=10) or testosterone propionate (TP; 5 mg/kg intramuscular (IM) injection, AAS, n=10) five times per week for 5 weeks, totaling 25 applications during the treatment. Aggression tests were performed at the end of the cycle (P54-56), whereas open-field tests (OFTs), elevated plus maze (EPM) behavioral tests and measurements of heart rate variability (HRV), fluid intake and pathology were conducted in the adult phase (P87-92). The AAS group showed greater aggressiveness in the pubertal phase and higher levels of horizontal and vertical exploration and anxiety-related behavior in the adult phase than the control group (P<0.05). HRV tests showed an increase in sympathetic autonomic modulation, and hydroelectrolytic assessment showed lower basal intake levels of hypertonic saline than the control group (P<0.05), without statistically significant changes in the basal intake of water. These data together suggest that the use of AAS during the prepubertal phase induces behavioral, autonomic and hydroelectrolytic changes that manifest in the adult phase even when treatment is discontinued in late adolescence in rats.

The role of ADRB2 in myasthenia: genetic and immunological factors

To examine the possibility of using ADRB2 adrenergic receptor agonists for correction of myasthenia-induced immunological and motor disturbances, a method of anti-ADRB2 antibody assay by ELISA was developed. The haplotype of ADRB2 gene was determined by MLPA-PCR in 34 myasthenia patients; blood sera from 40 patients were examined. The content of antibodies against ADRB2 receptors was elevated in 12 of 30 patients with generalized form of myasthenia. Arg-Arg in position 16 in ADRB2 receptors determines the developmental risk of side effects, while Gly-Gly in the same codon determines tolerance to β2-adrenoceptor agonists and is associated with more severe course of myasthenia and resistance to β2-adrenoceptor agonists treatment with ADRB2 agonists. The study demonstrated the possibility of using ADRB2 obtained gene engineering technique for quantitatively assay the autoantibodies.

Patterns of nicotinic receptor antagonism II: cardiovascular effects in rats

BACKGROUND

Tobacco cessation pharmacotherapies currently are limited to nicotine itself, the partial nicotine agonists varenicline and cytisine, and the antidepressant bupropion. Compared with agonists, nicotinic antagonists such as the noncompetitive, nonselective compound mecamylamine, and the competitive, α4β2-preferring antagonist dihydro-β-erythroidine (DHβE) may be a novel approach to the treatment of tobacco smoking as both are effective antagonists of nicotine's central effects. Considering nicotinic acetylcholine receptors mediate critical peripheral effects of acetylcholine, such as cardiovascular effects, it is important to study how nicotinic antagonists would alter the cardiovascular system and the cardiovascular changes induced by nicotine.

METHODS

The effects of several nicotinic agonists and antagonists on blood pressure and heart rate were measured in conscious, unrestrained rats following parenteral administration using a telemetry system.

RESULTS

Nicotine and other nicotinic receptor agonists (epibatidine, varenicline, and cytisine) produced similar increases in blood pressure, whereas their effects on heart rate were biphasic. The cardiovascular changes were attenuated by the nonselective nicotine antagonist, mecamylamine, but the peripherally restricted antagonist hexamethonium blocked only the agonist-induced changes in blood pressure. The α7-preferring antagonist, MLA, and the α4β2-preferring antagonist, DHβE, were much less effective in blocking the agonist-induced cardiovascular changes, indicating that nicotine's cardiovascular effects, are due to activation at autonomic ganglia involving nicotinic receptor subtypes other than α4, α7, or β2.

CONCLUSIONS

The data indicate that the cardiovascular effects of nicotine and nicotine-like agents are mediated through receptor mechanisms that are distinct from those that mediate the central effects of nicotine.

Preservation of α-3 neuronal nicotinic acetylcholine receptor expression in sympathetic ganglia after brain death

The goal of this study was to evaluate if the immunohistochemical expression of alpha-3 neuronal nicotinic acetylcholine receptor subunit in sympathetic ganglia remains stable after brain death, determining the possible use of sympathetic thoracic ganglia from subjects after brain death as study group. The third left sympathetic ganglion was resected from patients divided in two groups: BD-organ donors after brain death and CON-patients submitted to sympathectomy for hyperhidrosis (control group). Immunohistochemical staining for alpha-3 neuronal nicotinic acetylcholine receptor subunit was performed; strong and weak expression areas were quantified in both groups. The BD group showed strong alpha-3 neuronal nicotinic acetylcholine receptor expression in 6.55% of the total area, whereas the CON group showed strong expression in 5.91% (p = 0.78). Weak expression was found in 6.47% of brain-dead subjects and in 7.23% of control subjects (p = 0.31). Brain death did not affect the results of the immunohistochemical analysis of sympathetic ganglia, and its use as study group is feasible.

Alpha-adrenergic receptor gene polymorphisms and cardiovascular reactivity to stress in Black adolescents and young adults

Cardiovascular reactivity to stress and α-adrenergic receptor (α-AR) function may contribute to the development of hypertension. As Black Americans have an increased risk of hypertension, we evaluated associations between α(1A) -AR (Arg492Cys), α(2A) -AR (-1291C/G), and α(2B) -AR (Ins/Del301-303) gene variants and cardiovascular reactivity in 500 normotensive Black youth. Heart rate, preejection period, total peripheral resistance, and blood pressure were measured during cold and psychological stress. The Arg492Cys polymorphism in the α(1A) -AR gene was associated with heart rate reactivity to stress, but the association depended on sex. The -1291C/G promoter polymorphism in the α(2A) -AR gene was associated with vascular reactivity to stress; vasoconstriction increased as a linear function of the number of copies of the variant G allele. Thus, specific associations emerged between genetic variations in α-Ars and cardiovascular reactivity in young Blacks.

Preliminary investigation of concurrent administration of phenylbutazone and romifidine in healthy horses

OBJECTIVE

To characterize the cardiorespiratory and electrocardiographic effects of the combined administration of phenylbutazone and romifidine.

STUDY DESIGN

Prospective four-period, four-treatment, blinded, randomized, crossover trial.

ANIMALS

Five, healthy, mixed breed horses.

METHODS

Prior to treatment administration, a catheter was introduced into the intra-thoracic cranial vena cava via the jugular vein and a subcutaneously located carotid artery was catheterised. All treatments were administered intravenously (IV) and consisted of saline placebo (PLC), phenylbutazone (PBZ, 4.4 mg kg(-1) ) romifidine (ROM, 80 μg kg(-1) ) and a combination of phenylbutazone (4.4 mg kg(-1) ) and romifidine (80 μg kg(-1) ). There was at least a 1 week washout period between treatments. Heart rate (HR), respiratory rate (f(R) ), systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures and central venous pressure (CVP) were recorded for baseline (prior to drug administration) and at 5 minute intervals thereafter for 30 minutes. Electrocardiographic abnormalities were recorded. Data were analyzed by anova.

RESULTS

For the cardiovascular variables there were no statistically significant (p>0.05) differences between horses treated with ROM and PBZ_ROM. Statistically significant (p<0.05) differences only occurred between treatments with romifidine (ROM and PBZ_ROM) and without romifidine (PLC and PBZ). Within treatments, for ROM, changes over time were statistically significant (p<0.05) for HR, SAP, DAP, MAP and CVP. For PBZ_ROM, changes over time were statistically significant (p<0.05) for CVP. Sino-atrial and atrio-ventricular blocks occurred in horses treated with ROM and PBZ_ROM.

CONCLUSIONS AND CLINICAL RELEVANCE

The combined IV administration of phenylbutazone and romifidine had no statistically significant effect on cardiorespiratory variables. These limited data suggest no evidence why both agents should not be included in a preoperative medication protocol for healthy horses but do not exclude the possibility of interactions occurring in a larger population.

Association study of the β2-adrenergic receptor gene polymorphisms and hypertension in the Northern Han Chinese

Background

The β2-adrenergic receptor (ADRB2) gene has been widely researched as a candidate gene for essential hypertension (EH), but no consensus has been reached in different ethnicities. The aim of the present study was to evaluate the possible association between the ADRB2 gene polymorphisms and the EH risk in the Northern Han Chinese population.

Methodology/Principal Findings

This study included 747 hypertensive subjects and 390 healthy volunteers as control subjects in the Northern Han Chinese. Genotyping was performed to identify the C-47T, A46G and C79G polymorphisms of the ADRB2 gene. G allelic frequency of A46G polymorphism was significantly higher in hypertensive subjects (P = 0.011, OR = 1.287, 95%CI [1.059–1.565]) than that in controls. Significant association could also be found in dominant genetic model (GG+AG vs. AA, P = 0.006, OR = 1.497, 95%CI [1.121–1.998]), in homozygote comparison (GG vs. AA, P = 0.025, OR = 1.568, 95%CI [1.059–2.322]), and in additive genetic model (GG vs. AG vs. AA, P = 0.012, OR = 1.282, 95%CI [1.056–1.555]). Subgroup analyses performed by gender suggested that this association could be found in male, but not in female. Stratification analyses by obesity showed that A46G polymorphism was related to the prevalence of hypertension in the obese population (GG vs. AG vs. AA, P<0.001, OR = 1.645, 95%CI [1.258–2.151]). Significant interaction was found between A46G genotypes and body mass index on EH risk. No significant association could be found between C-47T or C79G polymorphism and EH risk. Linkage disequilibrium was detected between the C-47T, A46G and C79G polymorphisms. Haplotype analyses observed that the T-47-A46-C79 haplotype was a protective haplotype for EH, while the T-47-G46-C79 haplotype increased the risk.

Conclusions/Significances

We revealed that the ADRB2 A46G polymorphism might increase the risk for EH in the Northern Han Chinese population.

Resting sympathetic nerve activity is related to age, sex and arterial pressure but not to α2-adrenergic receptor subtype

OBJECTIVE

Sympathetic nerve hyperactivity has been associated with hypertension and heart failure and their cardiovascular complications. The α2-adrenergic receptors have been proposed to play a prominent role in the control of sympathetic neural output, and their malfunction to constitute a potential central mechanism for sympathetic hyperactivity of essential hypertension. Reports on the relationship between variant alleles of α2-adrenergic receptor subtypes and sympathetic drive or its effects, however, have not been consistent. Therefore, this study was planned to test the hypothesis that variant alleles of subtypes of α2-adrenergic receptors are associated with raised muscle sympathetic nerve activity (MSNA) in man.

METHODS

One hundred and seventy-two individuals, with a wide range of arterial pressure, were prospectively examined. Resting MSNA was quantified from multiunit bursts and from single units, and α2-adrenergic receptor subtypes were genotyped from DNA extracted from leucocytes and quantified by spectrophotometry.

RESULTS

No significant relationships between variant alleles of any of the α2A, α2B or α2C subtypes and raised muscle sympathetic activity were found. In contrast, MSNA showed a marked significant curvilinear relationship with age and systolic pressure; sex had a small but statistically significant effect. The α2-adrenergic receptor variants had a similar frequency when hypertensive and normotensive individuals were compared.

CONCLUSION

Variant alleles of three α2-adrenergic receptor subtypes were not related to resting muscle sympathetic nerve hyperactivity, indicating that their functional differences shown in vitro are not reflected in sympathetic activity in man. Age had a marked effect likely influencing arterial pressure through sympathetic activity.

Beta-adrenergic receptor gene polymorphisms and cardiovascular reactivity to stress in Black adolescents and young adults

Cardiovascular reactivity to stress and beta-adrenergic receptor (beta-AR) function may contribute to the development of hypertension. As Black Americans have an increased risk of hypertension, we evaluated associations between beta(1)-AR (Arg389Gly) and beta(2)-AR (Arg16Gly, Gln27Glu) gene variants and cardiovascular reactivity in 500 Black youth. Heart rate, preejection period, total peripheral resistance, and blood pressure reactivity were measured during cold and psychological stress. The Arg389Gly polymorphism in the beta(1)-AR was associated with preejection period reactivity in males but not in females. The Arg16Gly polymorphism in the beta(2)-AR was associated with diastolic blood pressure reactivity only during video game stress. An association between the Gln27Glu polymorphism in the beta(2)-AR and vascular reactivity depended on sex. Thus, specific patterns of associations emerged between genetic variations in beta-ARs and cardiovascular reactivity in young Blacks.

A46G and C79G polymorphisms in the β2-adrenergic receptor gene (ADRB2) and essential hypertension risk: a meta-analysis

No consensus has been reached on the association between the β2-adrenergic receptor polymorphisms A46G and C79G and essential hypertension risk. We performed a meta-analysis to confirm the possible association. After reviewing 303 reports in PubMed and 359 reports in Embase, we included in our meta-analysis 18 articles (20 studies) that met our inclusion criteria. The fixed-effects model and the random-effects model were applied for dichotomous outcomes to combine the results of the individual studies. There was no statistical association between A46G and hypertension risk in all subjects, Asians or Caucasians. However, an association was observed in the dominant genetic model (AA vs. (AG+GG)) (P=0.04, odds ratio (OR)=1.38, 95% confidence interval (CI) 1.01-1.87, P(heterogeneity)=0.98, fixed-effects model) in the subgroup of mixed Africans. No overall statistical association could be found between C79G and hypertension risk or any ethnic subgroup. In the research conducted on severe hypertension (systolic blood pressure ≥160 mm Hg and/or diastolic blood pressure ≥95 mm Hg hypertensive population), significant association was found in the dominant genetic model (CC vs. (CG+GG)) (P=0.04, OR=1.38, 95% CI 1.02-1.86, P(heterogeneity)=0.03, random-effects model), and there was also a borderline significance between the C79 allele and severe hypertension (P=0.05, OR=1.26, 95% CI 1.00-1.57, P(heterogeneity)=0.04, random-effects model). No association could be found in this study between the two polymorphisms and stage 2 hypertension. More studies stratified for different ethnicities and different stages of hypertension should be performed in the future.

Lifestyle modifies the relationship between body composition and adrenergic receptor genetic polymorphisms, ADRB2, ADRB3 and ADRA2B: a secondary analysis of a randomized controlled trial of physical activity among postmenopausal women

Genetic variations in the adrenergic receptor (ADR) have been associated with body composition in cross-sectional studies. Recent findings suggest that ADR variants may also modify body composition response to lifestyle. We assessed the role of ADR variants in body composition response to 12 months of resistance training versus control in previously sedentary postmenopausal women. Randomized trial completers were genotyped for A2B (Glu9/12) by fragment length analysis, and B2 (Gln27Glu) and B3 (Trp64Arg) by TaqMan (n = 148, 54% hormone therapy users). Associations between genotypes and body composition, by dual energy X-ray absorptiometry, were analyzed using univariate models. There was no main effect of individual genes on change in body composition, however, gene x exercise interactions were observed for A2B (Glu9/12) and B2 (Gln27Glu) on change in lean soft tissue (LST, p = 0.02); exercisers on the A2B (Glu9-) background gained LST compared to a loss among controls over 12 months (p < 0.05), with no significant intervention effect on the A2B (Glu9+) background. Similarly, there was a significant LST gain with exercise on the B2 (Glu27+) background compared to loss among controls and no intervention effect on the B2 (Glu27-) background. A non-significant association between total body fat (TBF) and B3 (Trp64Arg) persisted among sedentary controls only when intervention groups were separated (%TBF gain with B3 (Arg64+) carriage, p = 0.03); exercisers lost TBF regardless of genotype. In summary, effect modification by lifestyle was demonstrated on ADRA2B, B2, and B3 genetic backgrounds. Individuals with certain ADR genotypes may be more vulnerable to adverse changes in body composition with sedentary behavior, thus these candidate genes warrant further study.

Interaction between renin-angiotensin and sympathetic nervous systems in a rat model of pressure overload cardiac hypertrophy

1 A raised cardiac workload activates neurohormones which will increase muscle mass and shift contractility to the right along the Frank-Starling curve. 2 This study examined the interaction between the SNS and RAS in contributing to vascular responsiveness following the development of cardiac hypertrophy due to aortic banding. 3 Sprague Dawley rats (180-200 g) were assigned to one of six groups; Normal, Sham-operated, Aortic Banded (AB), Aortic Banded treated with losartan (ABLOS), Aortic Banded treated with 6-hydroxydopamine (ABSYMP) and Aortic banded treated with both losartan and 6-hydroxydopamine (ABSYMPLOS). A constricting band was placed around the supra renal aorta on day zero with drug treatment from day 37 to day 44. Vasopressor responses to noradrenaline, phenylephrine, methoxamine and angiotensin II were measured on day 45. 4 The magnitudes of the MAP responses to all vasoactive agents, expressed as percentage changes, were similar in Normal and Sham groups, but reduced in the AB group. ABLOS group showed attenuated response to ANGII whereas all responses were enhanced in the ABSYM group. 5 A positive interaction between the two systems was observed with alpha(1A)-adrenoceptors identified as a major component of SNS and AT(1) receptors of RAS to induce vasopressor effects.

Influence of beta2-adrenoceptor gene polymorphisms on beta2-adrenoceptor expression in human lung

BACKGROUND

The aim of the present study was to establish whether polymorphisms, especially those within the promoter region, of the beta(2)-adrenoceptor gene (ADRB2) influence beta(2)-adrenoceptor expression in human lung.

METHODS

The density of beta-adrenoceptors in human lung tissue (n=88) was determined by saturation binding using the radioligand, iodinated cyanopindolol. Discrimination of beta(1)- and beta(2)-adrenoceptors was determined using the highly selective beta(1)-adrenoceptor antagonist, CGP20712A. Genotype was determined at 5 positions of ADRB2 previously reported as polymorphic. Potential influences of single nucleotide polymorphisms (SNPs) within the promoter region (-367, -47) and coding block (46, 79, 491) of ADRB2 on beta(2)-adrenoceptor expression were investigated.

RESULTS

The density of beta(2)-adrenoceptors was variable among the 88 lung preparations studied ranging from 17 to 177fmol/mg protein (mean+/-S.E.M., 72+/-4fmol/mg protein). There was no influence of genotype on beta(2)-adrenoceptor expression for any of the polymorphisms studied except at position 491. The polymorphism at position 491C>T, leading to a change from thr to ile at amino acid 164, is uncommon. Preparations genotyped as heterozygous (126+/-15fmol/mg protein; n=5) expressed significantly (P=0.0005) higher levels of beta(2)-adrenoceptor than those that were homozygous (69+/-4fmol/mg protein; n=83).

CONCLUSION

With the exception of position 491, these data indicate that polymorphisms of ADRB2 do not influence beta(2)-adrenoceptor expression in human lung.

Identification of a novel 12-nucleotide insertion polymorphism in the promoter region of ADRA2B: full linkage with the 9-nucleotide deletion in the coding region and influence on transcriptional activity

The alpha(2B)-adrenoceptor (alpha(2B)-AR) mediates vasoconstriction and a common polymorphism (+901 Ins/Del), located in the coding region of the human alpha(2B)-AR gene (ADRA2B), has been demonstrated to affect receptor function in vitro. In this study, we have identified a novel polymorphism corresponding to the insertion of 12-nucleotides (GGGACGGCCCTG) at position -4825 relative to the start codon (-4825 del/ins) in the far upstream region of the ADRA2B promoter. The genotyping of 71 unrelated Finnish individuals showed that the -4825 ins polymorphism is common and in complete linkage with the Del polymorphism at position +901 and a G/C substitution at position -98. Transfection of various cell lines with luciferase constructs containing a 5.5 kb fragment of the ADRA2B promoter region indicated that the 12-nucleotide insertion at -4825 resulted in a large reduction of transcriptional activity. Electrophoretic mobility shift assays with oligonucleotide probes corresponding to the two ADRA2B alleles demonstrated that the region where the -4825 del/ins variation occurs binds nuclear proteins and that the 12-nucleotide insertion affects the pattern of bound transcription factors. Altogether, the present findings show that the previously identified +901 Del polymorphism is linked with a variation in the ADRA2B promoter that affects transcriptional activity in vitro. The molecular mechanisms underlying this effect are still unclear but a possible impact of the -4825 ins polymorphism on alpha(2B)-AR expression would merit to be examined in vivo as a diminution of promoter activity may limit the functional consequences of the +901 Del polymorphism.

Cardiovascular response to beta-adrenergic blockade or activation in 23 inbred mouse strains

We report the characterisation of 27 cardiovascular-related traits in 23 inbred mouse strains. Mice were phenotyped either in response to chronic administration of a single dose of the β-adrenergic receptor blocker atenolol or under a low and a high dose of the β-agonist isoproterenol and compared to baseline condition. The robustness of our data is supported by high trait heritabilities (typically H²>0.7) and significant correlations of trait values measured in baseline condition with independent multistrain datasets of the Mouse Phenome Database. We then focused on the drug-, dose-, and strain-specific responses to β-stimulation and β-blockade of a selection of traits including heart rate, systolic blood pressure, cardiac weight indices, ECG parameters and body weight. Because of the wealth of data accumulated, we applied integrative analyses such as comprehensive bi-clustering to investigate the structure of the response across the different phenotypes, strains and experimental conditions. Information extracted from these analyses is discussed in terms of novelty and biological implications. For example, we observe that traits related to ventricular weight in most strains respond only to the high dose of isoproterenol, while heart rate and atrial weight are already affected by the low dose. Finally, we observe little concordance between strain similarity based on the phenotypes and genotypic relatedness computed from genomic SNP profiles. This indicates that cardiovascular phenotypes are unlikely to segregate according to global phylogeny, but rather be governed by smaller, local differences in the genetic architecture of the various strains.

Polymorphisms determine beta-adrenoceptor conformation: implications for cardiovascular disease and therapy

Beta(1)- and beta(2)-adrenoceptors are crucial regulators of cardiovascular function. Agonists and antagonists at these receptor subtypes are cornerstones in the treatment of cardiovascular disease. In humans, both of the genes encoding the beta(1)- and beta(2)-adrenoceptors carry frequent polymorphisms resulting in different variants of the receptor proteins. Whether the polymorphic nature of the receptors causes the clinically observed differences with respect to the response of the patients to therapeutic drugs is currently a matter of intense discussion. Here, we discuss recent progress regarding the determination of beta-adrenoceptor conformational changes and how these can help to clarify this issue. Specifically, novel optical methods enable us to directly assess the functional importance of beta-adrenoceptor polymorphisms on ligand-induced changes of receptor conformation. The ability to determine polymorphism-dependent differences in drug efficacy directly on the receptor level might develop into an important approach to establish individualized drug therapies based on the genetic determinants of the patients.