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Sample records for adrenergic receptor antagonist

  1. Prazosin, an alpha 1-adrenergic receptor antagonist, suppresses experimental autoimmune encephalomyelitis in the Lewis rat.

    PubMed Central

    Brosnan, C F; Goldmuntz, E A; Cammer, W; Factor, S M; Bloom, B R; Norton, W T

    1985-01-01

    Prazosin, an antagonist of alpha 1-adrenergic receptors, has been found to suppress the clinical and histological expression of experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. Suppression was more significant in females than in males and was a dose-dependent phenomenon. Analysis of the effect of other adrenergic receptor antagonists supports the conclusion that the suppressive effect of prazosin is a consequence of blockade of the alpha 1-receptor since treatment with either the alpha 2-antagonist yohimbine or the beta-antagonist propranolol exacerbated the disease, whereas treatment with the long-acting mixed alpha 1/alpha 2-antagonist phenoxybenzamine had some suppressive activity. Treatment with prazosin was also able to suppress clinical and histological signs of EAE in animals sensitized by adoptive transfer with activated spleen or lymph node cells. Whether prazosin acts through altering vascular permeability or the immune response, or both, remains to be determined. Images PMID:2994053

  2. Comparison of the β-Adrenergic Receptor Antagonists Landiolol and Esmolol: Receptor Selectivity, Partial Agonism, and Pharmacochaperoning Actions.

    PubMed

    Nasrollahi-Shirazi, Shahrooz; Sucic, Sonja; Yang, Qiong; Freissmuth, Michael; Nanoff, Christian

    2016-10-01

    Blockage of β1-adrenergic receptors is one of the most effective treatments in cardiovascular medicine. Esmolol was introduced some three decades ago as a short-acting β1-selective antagonist. Landiolol is a more recent addition. Here we compared the two compounds for their selectivity for β1-adrenergic receptors over β2-adrenergic receptors, partial agonistic activity, signaling bias, and pharmacochaperoning action by using human embryonic kidney (HEK)293 cell lines, which heterologously express each human receptor subtype. The affinity of landiolol for β1-adrenergic receptors and β2-adrenergic receptors was higher and lower than that of esmolol, respectively, resulting in an improved selectivity (216-fold versus 30-fold). The principal metabolite of landiolol (M1) was also β1-selective, but its affinity was very low. Both landiolol and esmolol caused a very modest rise in cAMP levels but a robust increase in the phosphorylation of extracellular signal regulated kinases 1 and 2, indicating that the two drugs exerted partial agonist activity with a signaling bias. If cells were incubated for ≥24 hours in the presence of ≥1 μM esmolol, the levels of β1-adrenergic-but not of β2-adrenergic-receptors increased. This effect was contingent on export of the β1-receptor from endoplasmic reticulum and was not seen in the presence of landiolol. On the basis of these observations, we conclude that landiolol offers the advantage of: 1) improved selectivity and 2) the absence of pharmacochaperoning activity, which sensitizes cells to rebound effects upon drug discontinuation. PMID:27451411

  3. Modeling the interactions between alpha(1)-adrenergic receptors and their antagonists.

    PubMed

    Du, Lupei; Li, Minyong

    2010-09-01

    As crucial members of the G-protein coupled receptor (GPCR) superfamily, alpha (1)-adrenergic receptors (alpha(1)-ARs) are recognized to intervene the actions of endogenous catecholamines such as norepinephrine and epinephrine. So far three distinct alpha(1)-AR subtypes, alpha(1A), alpha(1B) and alpha(1D), have been characterized by functional analysis, radio-ligand binding and molecular biology studies. The alpha(1)-ARs are of therapeutic interest because of their distinct and critical roles in many physiological processes, containing hypertension, benign prostatic hyperplasia, smooth muscle contraction, myocardial inotropy and chronotropy, and hepatic glucose metabolism. Accordingly, designing subtype-selective antagonists for each of the three alpha(1)-AR subtypes has been an enthusiastic region of medicinal research. Even though a large number of studies on GPCRs have been conducted, understanding of how known antagonists bind to alpha(1)-ARs still remains sketchy and has been a serious impediment to search for potent and subtype-selective alpha(1)-AR antagonists because of the lack of detailed experimental structural knowledge. This review deliberates the simulation of alpha(1)-ARs and their interactions with antagonists by using ligand-based (pharmacophore identification and QSAR modeling) and structure-based (comparative modeling and molecular docking) approaches. Combined with experimental data, these computational attempts could improve our understanding of the structural basis of antagonist binding and the molecular basis of receptor activation, thus offering a more reasonable approach in the design of drugs targeting alpha(1)-ARs. PMID:20412040

  4. Analysis of hydrophobic interactions of antagonists with the beta2-adrenergic receptor.

    PubMed

    Novoseletsky, V N; Pyrkov, T V; Efremov, R G

    2010-01-01

    The adrenergic receptors mediate a wide variety of physiological responses, including vasodilatation and vasoconstriction, heart rate modulation, and others. Beta-adrenergic antagonists ('beta-blockers') thus constitute a widely used class of drugs in cardiovascular medicine as well as in management of anxiety, migraine, and glaucoma. The importance of the hydrophobic effect has been evidenced for a wide range of beta-blocker properties. To better understand the role of the hydrophobic effect in recognition of beta-blockers by their receptor, we carried out a molecular docking study combined with an original approach to estimate receptor-ligand hydrophobic interactions. The proposed method is based on automatic detection of molecular fragments in ligands and the analysis of their interactions with receptors separately. A series of beta-blockers, based on phenylethanolamines and phenoxypropanolamines, were docked to the beta2-adrenoceptor binding site in the crystal structure. Hydrophobic complementarity between the ligand and the receptor was calculated using the PLATINUM web-server (http://model.nmr.ru/platinum). Based on the analysis of the hydrophobic match for molecular fragments of beta-blockers, we have developed a new scoring function which efficiently predicts dissociation constant (pKd) with strong correlations (r(2) approximately 0.8) with experimental data. PMID:20373213

  5. Allosteric interactions between the antagonist prazosin and amiloride analogs at the human alpha(1A)-adrenergic receptor.

    PubMed

    Leppik, R A; Mynett, A; Lazareno, S; Birdsall, N J

    2000-03-01

    It has been demonstrated previously that amilorides can interact with a well defined allosteric site on the human alpha(2A)-adrenergic receptor. In this study, the question was explored as to whether the human alpha(1A)-adrenergic receptor also possesses an equivalent allosteric site. The six amilorides examined strongly increased the dissociation rate of the antagonist [(3)H]prazosin from the alpha(1A)-adrenergic receptor in a concentration-dependent manner. With the parent amiloride, the dissociation data were well fitted by an equation derived from the ternary complex allosteric model, compatible with amiloride acting at a defined allosteric site on the alpha(1A)-adrenergic receptor. In contrast, the dissociation data for [(3)H]prazosin in the presence of the amiloride analogs were not compatible with the equation derived from a one-allosteric-site model, but could be fitted well by an equation derived from a two-allosteric-site model. However, certain individual parameters could not be resolved. The observed dissociation rate constants increased steeply with increasing amiloride analog concentration, and in some cases the data could be fitted with a logistic equation. The slope factors calculated from such fits were 1.2 to 2.1. It is concluded that the structure-binding relationships of the amilorides at the alpha(1A)- and alpha(2A)-adrenergic receptors are different. The interactions of the five amiloride analogs, but not the parent amiloride, with the alpha(1A)-adrenergic receptor are compatible with the presence of two (but not one) allosteric sites, and is thus more complex than that found for the alpha(2A)-adrenergic receptor. PMID:10692482

  6. Direct intra-accumbal infusion of a beta-adrenergic receptor antagonist abolishes WIN 55,212-2-induced aversion

    PubMed Central

    Carvalho, Ana Franky; Van Bockstaele, Elisabeth J.

    2011-01-01

    The cannabinoid system is known to interact with a variety of neuromodulators in the central nervous system and impacts diverse behaviors. Previous studies have demonstrated that limbic norepinephrine is a critical determinant in the behavioral expression of cannabinoid-induced aversion. The present study was carried out to define the adrenergic receptor subtype involved in mediating cannabinoid-induced behavioral responses. An acute microinjection of the β1-adrenergic receptor blocker, betaxolol, directly into the nucleus accumbens (Acb), was able to prevent WIN 55,212-2-induced aversion, but not lithium-induced aversion, as measured in a place conditioning paradigm. These results suggest that noradrenergic transmission in the Acb is important for cannabinoid-induced aversion and that beta-adrenergic antagonists may be effective in counteracting negative side effects of cannabinoid-based agents. PMID:21693171

  7. Treatment of pediatric pyogenic granulomas using β-adrenergic receptor antagonists.

    PubMed

    Wine Lee, Lara; Goff, Kiera L; Lam, Joseph M; Low, David W; Yan, Albert C; Castelo-Soccio, Leslie

    2014-01-01

    Propranolol and timolol are nonselective ß-adrenergic antagonists that induce peripheral vasoconstriction and affect angiogenic cytokines. Oral and topical ß-blocker therapy has become the de facto first-line treatment for complicated infantile hemangiomas because of its superior efficacy and tolerability. Pyogenic granulomas or lobular capillary hemangiomas are common acquired vascular tumors accounting for 0.5% of all skin nodules in children. Although they are benign vascular proliferations, treatment is often sought because of recurrent episodes of bleeding and for cosmetic considerations. Numerous treatment options are available, but recurrence rates are high. Noninvasive methods of treatment are being sought, particularly for young children. Herein we report a series of seven cases of cutaneous and mucosal pyogenic granulomas treated successfully using oral or topical ß-blockers. PMID:24138457

  8. Different affinity states of alpha-1 adrenergic receptors defined by agonists and antagonists in bovine aorta plasma membranes

    SciTech Connect

    Jagadeesh, G.; Deth, R.C.

    1987-11-01

    Evidence for a nonlinear relationship between alpha-1 adrenergic receptor occupancy and tissue responses, together with the finding of different affinity states for agonist binding, has raised the possibility of functional heterogeneity of alpha-1 adrenergic receptors. We have conducted studies to examine: 1) binding characteristics of (/sup 3/H)prazosin, 2) competition of antagonists at these sites and 3) different affinity states of the receptor for agonists and modulation of these states by 5'-guanylylimidodiphosphate (Gpp(NH)p). A plasma membrane-enriched vesicular fraction (F2; 15%/33% sucrose interphase) was prepared from the muscular medial layer of bovine thoracic aorta. (/sup 3/H)Prazosin binding was characterized by a monophasic saturation isotherm (KD = 0.116 nM, Bmax = 112 fmol/mg of protein). Antagonist displacement studies yielded a relative potency order of prazosin greater than or equal to WB4104 much greater than phentolamine greater than corynanthine greater than yohimbine greater than or equal to idazoxan greater than rauwolscine. Competition curves for unlabeled prazosin, WB4101 (2-(2,6-dimethoxyphenoxyethyl)-aminomethyl-1,4 benzodioxane) and phentolamine were shallow and were best modeled to two binding sites with picomolar and nanomolar KD values. Gpp(NH)p was without effect on antagonist affinity. Agonist (epinephrine, norepinephrine and phenylephrine) competition with (/sup 3/H)prazosin binding was biphasic with pseudo-Hill slopes less than 1.0. Binding was best described by a two-site model in which the average contribution of high affinity sites was 23% of total binding. KD values for the high affinity site ranged from 2.9 to 18 nM, and 3.9 to 5.0 microM for the low affinity site.

  9. (-)(125I)-iodopindolol, a new highly selective radioiodinated beta-adrenergic receptor antagonist: measurement of beta-receptors on intact rat astrocytoma cells

    SciTech Connect

    Barovsky, K.; Brooker, G.

    1980-01-01

    (-)-Pindolol, one of the most potent beta-adrenergic receptor antagonists, was radioiodinated using chloramine-T oxidation of carrier-free Na 125I and separated from unreacted pindolol to yield 2200 Ci/mmole (-)-(125I)-iodopindolol ((-)-(125I)-IPin). Mass and ultraviolet spectra confirmed that the iodination occurred on the indole ring, presumably at the 3 position. The binding of radiolabeled (-)-(125I)-IPin to beta-adrenergic receptors has been studied using intact C6 rat astrocytoma cells (2B subclone) grown in monolayer cultures. Binding of (-)(125IPin was saturable with time and concentration. Using 13 pM (-)-(125I)IPin, binding equilibrium was reached in 90 min at 21-22 degrees C. The reverse rate constant was 0.026 min-1 at 21/sup 0/C. Specific binding (expressed as 1 microM(-)-propranolol displaceable counts) of (-)-(125I)-IPin was 95% of total binding. Scatchard analysis of (-)-(125I)-I)Pin binding revealed approximately 4300 receptors/cell and a dissociation constant of 30 pM. This was in excellent agreement with the kinetically determined dissociation constant of 35 pM. Displacement by propranolol and isoproterenol showed that (-)-(125I)-IPin binding sites were pharmacologically and stereospecifically selective. These results indicate that (-)-(125I)-IPin, a pure (-)-stereoisomer, high specific activity radioligand, selectively binds to beta-adrenergic receptors in whole cells with a high percentage of specific binding and should therefore be useful in the study and measurement of cellular beta-adrenergic receptors.

  10. [Beta-adrenergic receptor blocker poisoning].

    PubMed

    Reingardiene, Dagmara

    2007-01-01

    Beta-adrenergic receptor blocking drugs are used in the treatment of hypertension, angina, myocardial infarction, cardiac dysrhythmia, cardiomyopathy, migraine headache, thyrotoxicosis, and glaucoma. beta-adrenergic receptor blocking agents are competitive antagonist at beta(1), beta(2), or both types of adrenergic receptors. Overdoses of beta-adrenergic receptor blockers are uncommon, but are associated with significant morbidity and mortality. This review article discusses the properties of beta-adrenergic receptor blockers, presents the doses of these drugs causing toxicity and doses, after ingestion of which, referral to an emergency department is recommended. Clinical presentation of overdose (the cardiovascular, neurologic manifestations, pulmonary and other complications), diagnosis, and treatment (gastrointestinal decontamination; the usage of atropine, phosphodiesterase inhibitors, glucagon, insulin; indications for cardiac pacing, extracorporeal procedures of drug removal, etc.) are analyzed. In addition, this article focuses on clinical course and prognosis of beta-blocker overdose. PMID:17768375

  11. [Effect of Agonists and Antagonists of α2 Adrenergic Receptors on Choice of Reinforcement Value in Rats with Different Levels of Impulsivity].

    PubMed

    Zaichenko, M I; Merzhanova, G Kh; Bazhenova, D A

    2015-01-01

    The influence of drugs, agonist (clonidine) and antagonist (yohimbine) of α2-adrenergic receptors 5-HT2 on the behavior of rats tested by the method of choice to the value of reinforcement was investigated. Based on the selection of a rat the pedal for immediate poor and delayed valuable reinforcement rats were divided into 3 groups. Rats, in most cases, choosing valuable delayed reinforcements were classified as low-impulsive, those who mainly chosen poor immediate reinforcement to the high-impulsive group. Rats who were not able to determine, was ambivalent group. Administration (i.p.) of the α2-adrenergic receptors agonist clonidine resulted in a reduction of the select valuable delayed reinforcement by low-impulsive animals and increasing the number of missing responses of pressing the pedal in high-impulsive animals. Clonidine also reduced the latency of nose-poking in all groups of animals. The antagonist of these receptors yohimbine did not cause changes in the choice of the reinforcement in all groups of animals. At the same time yohimbine caused a significant reduction in the number of missing responses. The results suggest that the effect of drugs used in this work on α2-adrenergic receptors depends on the individual feature of rats, in particular from high and low degree of impulsivity. PMID:26841662

  12. Muscarinic receptor antagonist and an alpha-adrenergic agonist are required in combination to provide stable mydriasis following intravitreal injection in mice

    PubMed Central

    Mojumder, Deb Kumar

    2010-01-01

    Tropicamide (muscarinic receptor antagonist) and phenylephrine (α-adrenergic receptor agonist) are commonly used to dilate the pupils by topical application. These two eye drops are often used, singly or in combination, to dilate the pupil and perform acute light-evoked physiological experiments (electroretinography, for example), before and after intravitreal injections of pharmacological agents, as an assay for their affect on retinal activity. This study wanted to determine whether treatment with one of these drugs, or with both, is most effective in maintaining mydriasis after intravitreal injections. Changes in pupillary dilation before and after intravitreal injection of balanced salt solution (0.5 µl) were recorded. Phenylephrine (α-adrenergic agonist) and tropicamide (muscarinic agonist) when combined, but not singly, produced full and stable pupillary dilation following intravitreal injections. Re-instillation of topical mydriatics after intravitreal injections was required for maximal pupillary dilation. A combination of a muscarinic receptor antagonist and an alpha-adrenergic agonist is required for stable mydriasis following intravitreal injection. PMID:20852745

  13. Actions of adenosine A1 and A2 receptor antagonists on CFTR antibody-inhibited β-adrenergic mucin secretion response

    PubMed Central

    Pereira, M M C; Lloyd Mills, C; Dormer, R L; McPherson, M A

    1998-01-01

    The cystic fibrosis gene protein, the cystic fibrosis transmembrane conductance regulator (CFTR) acts as a chloride channel and is a key regulator of mucin secretion. The mechanism by which 3-isobutyl-1-methylxanthine (IBMX) corrects the defect in CFTR mediated β-adrenergic stimulation of mucin secretion has not been determined. The present study has investigated the actions of adenosine A1 and A2 receptor antagonists to determine whether ability to stimulate mucin secretion correlates with correction of CFTR antibody inhibited β-adrenergic response and whether excessive cyclic AMP rise is required.CFTR antibodies were introduced into living rat submandibular acini by hypotonic swelling. Following recovery, mucin secretion in response to isoproterenol was measured.The adenosine A1 receptor antagonist, 8 cyclopentyltheophylline (CPT) was a less potent stimulator of mucin secretion than was the A2 receptor antagonist dimethylpropargylxanthine (DMPX). A concentration of CPT close to the Ki for A1 receptor antagonism (10 nM) did not stimulate mucin secretion.DMPX, although a potent stimulator of mucin secretion, did not correct CFTR antibody inhibited mucin secretion.CPT corrected defective CFTR antibody inhibited mucin secretion at a high (1 mM) concentration, suggesting a mechanism other than adenosine receptor antagonism.DMPX potentiated the isoproterenol induced cyclic AMP rise, whereas CPT did not.Correction of the defective CFTR mucin secretion response did not correlate with ability to stimulate mucin secretion and did not require potentiation of β-adrenergic induced increases in cyclic AMP. This affords real promise for the development of a selective drug treatment for cystic fibrosis. PMID:9831904

  14. The α1 Adrenergic Receptor Antagonist Prazosin Reduces Heroin Self-Administration in Rats with Extended Access to Heroin Administration

    PubMed Central

    Greenwell, Thomas N.; Walker, Brendan M.; Cottone, Pietro; Zorrilla, Eric P.; Koob, George F.

    2009-01-01

    Previous studies have reported that noradrenergic antagonists alleviate some of the symptoms of opiate withdrawal and dependence. Clinical studies also have shown that modification of the noradrenergic system may help protect patients from relapse. The present study tested the hypothesis that a dysregulated noradrenergic system has motivational significance in heroin self-administration in dependent rats. Prazosin, an α1-adrenergic antagonist (0.5, 1.0, 1.5 and 2.0 mg/kg, i.p.), was administered to adult male Wistar rats with a history of limited (1 h/day; short access) or extended (12 h/day; long access) access to intravenous heroin self-administration. Prazosin dose-dependently reduced heroin self-administration in long-access rats but not short-access rats, with 2 mg/kg of systemic prazosin significantly decreasing 1 h and 2 h heroin intake. Prazosin also reversed some changes in meal pattern associated with extended heroin access, including the taking of smaller and briefer meals (at 3 h), while also increasing total food intake and slowing the eating rate within meals (both 3 h and 12 h). The data show that the α1-adrenergic system may contribute to mechanisms that promote dependence in rats with extended drug access, while also stimulating their food intake by restoring meals to the normal size and duration. PMID:18703080

  15. Effects of the beta-adrenergic receptor antagonist Propranolol on dyskinesia and L-DOPA-induced striatal DA efflux in the hemi-parkinsonian rat.

    PubMed

    Bhide, Nirmal; Lindenbach, David; Barnum, Christopher J; George, Jessica A; Surrena, Margaret A; Bishop, Christopher

    2015-07-01

    Dopamine (DA) replacement therapy with L-DOPA continues to be the primary treatment of Parkinson's disease; however, long-term therapy is accompanied by L-DOPA-induced dyskinesias (LID). Several experimental and clinical studies have established that Propranolol, a β-adrenergic receptor antagonist, reduces LID without affecting L-DOPA's efficacy. However, the exact mechanisms underlying these effects remain to be elucidated. The aim of this study was to evaluate the anti-dyskinetic profile of Propranolol against a panel of DA replacement strategies, as well as elucidate the underlying neurochemical mechanisms. Results indicated that Propranolol, in a dose-dependent manner, reduced LID, without affecting motor performance. Propranolol failed to alter dyskinesia produced by the D1 receptor agonist, SKF81297 (0.08 mg/kg, sc), or the D2 receptor agonist, Quinpirole (0.05 mg/kg, sc). These findings suggested a pre-synaptic mechanism for Propranolol's anti-dyskinetic effects, possibly through modulating L-DOPA-mediated DA efflux. To evaluate this possibility, microdialysis studies were carried out in the DA-lesioned striatum of dyskinetic rats and results indicated that co-administration of Propranolol (20 mg/kg, ip) was able to attenuate L-DOPA- (6 mg/kg, sc) induced DA efflux. Therefore, Propranolol's anti-dyskinetic properties appear to be mediated via attenuation of L-DOPA-induced extraphysiological efflux of DA. PMID:25866285

  16. The effect of Yohimbine, an alpha2 adrenergic receptor antagonist, on the growth hormone response to apomorphine in normal subjects.

    PubMed Central

    Lal, S; Thavundayil, J X; Krishnan, B; Nair, N P; Schwartz, G; Guyda, H

    1996-01-01

    Yohimbine HCl (16 mg po) administered 30 min before clonidine (CLON) (2 ug/kg infused over 10 min) (N = 5) or apomorphine HCl (Apo) (0.5 mg sc) (N = 10) antagonized the growth hormone (GH) response to CLON but had no effect on the GH response to Apo in normal men. This finding suggests that in humans, alpha2 adrenergic mechanisms do not modulate dopaminergic function, at least not in the hypothalamic-pituitary axis, and that the GH response to Apo is not mediated via an alpha2 adrenergic link. PMID:8820174

  17. The Combination of Marketed Antagonists of α1b-Adrenergic and 5-HT2A Receptors Inhibits Behavioral Sensitization and Preference to Alcohol in Mice: A Promising Approach for the Treatment of Alcohol Dependence

    PubMed Central

    Trovero, Fabrice; David, Sabrina; Bernard, Philippe; Puech, Alain; Bizot, Jean-Charles; Tassin, Jean-Pol

    2016-01-01

    Alcohol-dependence is a chronic disease with a dramatic and expensive social impact. Previous studies have indicated that the blockade of two monoaminergic receptors, α1b-adrenergic and 5-HT2A, could inhibit the development of behavioral sensitization to drugs of abuse, a hallmark of drug-seeking and drug-taking behaviors in rodents. Here, in order to develop a potential therapeutic treatment of alcohol dependence in humans, we have blocked these two monoaminergic receptors by a combination of antagonists already approved by Health Agencies. We show that the association of ifenprodil (1 mg/kg) and cyproheptadine (1 mg/kg) (α1-adrenergic and 5-HT2 receptor antagonists marketed as Vadilex ® and Periactine ® in France, respectively) blocks behavioral sensitization to amphetamine in C57Bl6 mice and to alcohol in DBA2 mice. Moreover, this combination of antagonists inhibits alcohol intake in mice habituated to alcohol (10% v/v) and reverses their alcohol preference. Finally, in order to verify that the effect of ifenprodil was not due to its anti-NMDA receptors property, we have shown that a combination of prazosin (0.5 mg/kg, an α1b-adrenergic antagonist, Mini-Press ® in France) and cyproheptadine (1 mg/kg) could also reverse alcohol preference. Altogether these findings strongly suggest that combined prazosin and cyproheptadine could be efficient as a therapy to treat alcoholism in humans. Finally, because α1b-adrenergic and 5-HT2A receptors blockade also inhibits behavioral sensitization to psychostimulants, opioids and tobacco, it cannot be excluded that this combination will exhibit some efficacy in the treatment of addiction to other abused drugs. PMID:26968030

  18. The Combination of Marketed Antagonists of α1b-Adrenergic and 5-HT2A Receptors Inhibits Behavioral Sensitization and Preference to Alcohol in Mice: A Promising Approach for the Treatment of Alcohol Dependence.

    PubMed

    Trovero, Fabrice; David, Sabrina; Bernard, Philippe; Puech, Alain; Bizot, Jean-Charles; Tassin, Jean-Pol

    2016-01-01

    Alcohol-dependence is a chronic disease with a dramatic and expensive social impact. Previous studies have indicated that the blockade of two monoaminergic receptors, α1b-adrenergic and 5-HT2A, could inhibit the development of behavioral sensitization to drugs of abuse, a hallmark of drug-seeking and drug-taking behaviors in rodents. Here, in order to develop a potential therapeutic treatment of alcohol dependence in humans, we have blocked these two monoaminergic receptors by a combination of antagonists already approved by Health Agencies. We show that the association of ifenprodil (1 mg/kg) and cyproheptadine (1 mg/kg) (α1-adrenergic and 5-HT2 receptor antagonists marketed as Vadilex ® and Periactine ® in France, respectively) blocks behavioral sensitization to amphetamine in C57Bl6 mice and to alcohol in DBA2 mice. Moreover, this combination of antagonists inhibits alcohol intake in mice habituated to alcohol (10% v/v) and reverses their alcohol preference. Finally, in order to verify that the effect of ifenprodil was not due to its anti-NMDA receptors property, we have shown that a combination of prazosin (0.5 mg/kg, an α1b-adrenergic antagonist, Mini-Press ® in France) and cyproheptadine (1 mg/kg) could also reverse alcohol preference. Altogether these findings strongly suggest that combined prazosin and cyproheptadine could be efficient as a therapy to treat alcoholism in humans. Finally, because α1b-adrenergic and 5-HT2A receptors blockade also inhibits behavioral sensitization to psychostimulants, opioids and tobacco, it cannot be excluded that this combination will exhibit some efficacy in the treatment of addiction to other abused drugs. PMID:26968030

  19. [The beta-adrenergic receptor].

    PubMed

    Bicho, M P; Manso, C F

    1992-12-01

    The Authors review the constitution and mechanism of action of the beta adrenergic receptor. It is part of a large family which includes visual pigments, muscarinic, serotonergic, olfactive and substance K receptors. Catecholamines given an electron to the receptor. It goes then successively to the alpha submit of Gs protein ant to adenylyl cyclase. The process of activation consists in a successive transfer of one electron. PMID:1337834

  20. Rat hepatic. beta. /sub 2/-adrenergic receptor: structural similarities to the rat fat cell. beta. /sub 1/-adrenergic receptor

    SciTech Connect

    Graziano, M.P.

    1984-01-01

    The mammalian ..beta../sub 2/-adrenergic receptor from rat liver has been purified by sequential cycles of affinity chromatography followed by steric-exclusion high performance liquid chromatography. Electrophoresis of highly purified receptor preparations on polyacrylamide gels in the presence of sodium dodecyl sulfate under reducing conditions reveals a single peptide M/sub r/ = 67,000, as judged by silver staining. Purified ..beta../sub 2/-adrenergic receptor migrates on steric-exclusion high performance liquid chromatography in two peaks, with M/sub r/ = 140,000 and 67,000. Specific binding of the high affinity, ..beta..-adrenergic receptor antagonists (-)(/sup 3/H)dihydroalprenolol and (-)(/sup 125/I)iodocyanopindolol to purified rat liver ..beta..-adrenergic receptor preparations displays stereoselectivity for (-)isomers of agonists and a rank order of potencies for agonists characteristics of a ..beta../sub 2/-adrenergic receptor. Radioiodinated, ..beta../sub 1/-adrenergic receptors from rat fat cells and ..beta../sub 2/-adrenergic receptors from rat liver purified in the presence of protease inhibitors comigrate in electrophoretic separations on polyacrylamide gels in the presence of sodium dodecyl sulfate as 67,000-M/sub r/ peptides. Autoradiograms of two dimensional partial proteolytic digests of the purified, radioiodinated rat liver ..beta../sub 2/-adrenergic receptor, generated with ..cap alpha..-chymotrypsin, S. aureus V8 protease and elastase reveal a pattern of peptide fragments essentially identical to those generated by partial proteolytic digests of the purified, radioiodinated ..beta../sub 1/-adrenergic receptor from rat fat cells, by these same proteases. These data indicate that a high degree of homology exists between these two pharmacologically distinct mammalian ..beta..-adrenergic receptor proteins.

  1. Antagonism of Lateral Amygdala Alpha1-Adrenergic Receptors Facilitates Fear Conditioning and Long-Term Potentiation

    ERIC Educational Resources Information Center

    Lazzaro, Stephanie C.; Hou, Mian; Cunha, Catarina; LeDoux, Joseph E.; Cain, Christopher K.

    2010-01-01

    Norepinephrine receptors have been studied in emotion, memory, and attention. However, the role of alpha1-adrenergic receptors in fear conditioning, a major model of emotional learning, is poorly understood. We examined the effect of terazosin, an alpha1-adrenergic receptor antagonist, on cued fear conditioning. Systemic or intra-lateral amygdala…

  2. Human myometrial adrenergic receptors during pregnancy: identification of the alpha-adrenergic receptor by (/sup 3/H) dihydroergocryptine binding

    SciTech Connect

    Jacobs, M.M.; Hayashida, D.; Roberts, J.M.

    1985-07-15

    The radioactive alpha-adrenergic antagonist (/sup 3/H) dihydroergocryptine binds to particulate preparations of term pregnant human myometrium in a manner compatible with binding to the alpha-adrenergic receptor (alpha-receptor). (/sup 3/H) Dihydroergocryptine binds with high affinity (KD = 2 nmol/L and low capacity (receptor concentration = 100 fmol/mg of protein). Adrenergic agonists compete for (/sup 3/H) dihydroergocryptine binding sites stereo-selectively ((-)-norepinephrine is 100 times as potent as (+)-norepinephrine) and in a manner compatible with alpha-adrenergic potencies (epinephrine approximately equal to norepinephrine much greater than isoproterenol). Studies in which prazosin, an alpha 1-antagonist, and yohimbine, and alpha 2-antagonist, competed for (/sup 3/H) dihydroergocryptine binding sites in human myometrium indicated that approximately 70% are alpha 2-receptors and that 30% are alpha 1-receptors. (/sup 3/H) dihydroergocryptine binding to human myometrial membrane particulate provides an important tool with which to study the molecular mechanisms of uterine alpha-adrenergic response.

  3. Beta Adrenergic Receptors in Keratinocytes

    PubMed Central

    Sivamani, Raja K.; Lam, Susanne T.; Isseroff, R. Rivkah

    2007-01-01

    Synopsis Beta2 adrenergic receptors were identified in keratinocytes more than 30 years ago, but their function in the epidermis continues to be elucidated. Abnormalities in their expression, signaling pathway, or in the generation of endogenous catecholamine agonists by keratinocytes have been implicated in the pathogenesis of cutaneous diseases such as atopic dermatitis, vitiligo and psoriasis. New studies also indicate that the beta2AR also modulates keratinocyte migration, and thus can function to regulate wound re-epithelialization. This review focuses on the function of these receptors in keratinocytes and their contribution to cutaneous physiology and disease. PMID:17903623

  4. Blood flow distribution with adrenergic and histaminergic antagonists

    SciTech Connect

    Baker, C.H.; Davis, D.L.; Sutton, E.T.

    1989-03-01

    Superficial fibular nerve stimulation (SFNS) causes increased pre- and post-capillary resistances as well as increased capillary permeability in the dog hind paw. These responses indicate possible adrenergic and histaminergic interactions. The distribution of blood flow between capillaries and arteriovenous anastomoses (AVA) may depend on the relative effects of these neural inputs. Right hind paws of anesthetized heparinized dogs were vascularly and neurally isolated and perfused with controlled pressure. Blood flow distribution was calculated from the venous recovery of 85Sr-labeled microspheres (15 microns). The mean transit times of 131I-albumin and 85Sr-labeled microspheres were calculated. The effects of adrenergic and histaminergic antagonists with and without SFNS were determined. Phentolamine blocked the entire response to SFNS. Prazosin attenuated increases in total and AVA resistance. Yohimbine prevented increased total resistance, attenuated the AVA resistance increase, and revealed a decrease in capillary circuit resistance. Pyrilamine attenuated total resistance increase while SFNS increased capillary and AVA resistances. Metiamide had no effect on blood flow distribution with SFNS. The increase in AVA resistance with SFNS apparently resulted from a combination of alpha 1 and alpha 2 receptor stimulation but not histaminergic effects.

  5. Characterization of the Human Platelet α-Adrenergic Receptor

    PubMed Central

    Alexander, R. Wayne; Cooper, Barry; Handin, Robert I.

    1978-01-01

    Human platelets aggregate and undergo a release reaction when incubated with catecholamines. Indirect evidence indicates that these events are mediated through α-adrenergic receptors. We used [3H]dihydroergocryptine, an α-adrenergic antagonist, to identify binding sites on platelets that have the characteristics of α-adrenergic receptors. Catecholamines compete for the binding sites in a stereo-specific manner with the potency series of (−) epinephrine > (−) norepinephrine > (±) phenylephrine > (−) isoproterenol. The dissociation constant (Kd) of (−) epinephrine is 0.34 μM. Binding is saturable using a platelet particulate fraction but not with intact platelets. There are 0.130 pmol binding sites per milligram protein in fresh platelet membranes. This number represents approximately 100 binding sites per platelet. The Kd for [3H]-dihydroergocryptine was 0.003−0.01 μM. The α-adrenergic antagonist phentolamine (Kd = 0.0069 μM) was much more potent than the β-adrenergic antagonist (±) propranolol (Kd = 27 μM) in competing for the binding sites. The binding data were correlated with catecholamine-induced platelet aggregation and inhibition of basal and prostaglandin E1-stimulated adenylate cyclase. (−) Epinephrine was more potent than (−) norepinephrine in producing aggregation whereas (−) isoproterenol was ineffective. The threshold dose for inducing aggregation by (−) epinephrine was 0.46 μM. Phentolamine and dihydroergocyrptine blocked this response, whereas (±) propranolol had no effect. (−) Epinephrine and (−) norepinephrine inhibited basal and prostaglandin E1-stimulated adenylate cyclase in a dose-related manner. The concentration of (−) epinephrine inhibiting adenylate cyclase 50% was 0.7 μM. This inhibition was also blocked by phentolamine and dihydroergocryptine but not by (±) propranolol. The specificity of binding and the close correlation with α-adrenergic receptor-mediated biochemical and physiological responses

  6. Binding properties of aminophenyl carboxamide derivatives of the alpha/sub 2/-adrenergic receptor antagonists, rauwolscine and yohimbine: spatial and stereochemical considerations

    SciTech Connect

    Lanier, S.M.; Hess, H.J.; Grodsky, A.; Homcy, C.J.; Graham, R.M.

    1986-05-01

    The authors have recently characterized the radioiodinated analog of a carboxamide derivative of rauwolscine (RAU) (17 ..cap alpha..-hydroxy-20..cap alpha..-yohimban-16..beta..-(N-4-aminophenethyl)carboxamide) as a high-affinity probe for ..cap alpha../sub 2/-adrenergic receptors (..cap alpha../sub 2/-R). To investigate the spatial requirements of the receptor's ligand-binding site, the authors have synthesized carboxamide derivatives of RAU in which the aminophenyl group is separated from the parent compound by 0 (I), 2 (II) or 4 (III) atoms. In competition studies with /sup 3/H-RAU utilizing rat kidney membranes, I, RAU, II and III exhibited K/sub i/'s of 1.9 +/- 0.1, 4.7 +/- 0.2, 13 +/- 0.5 and 16 +/- 0.7 nM, respectively. The stereochemical requirements of the receptor's ligand binding site were also studied following the synthesis of similar carboxamide derivatives of yohimbine (YOH), a diastereoisomer of rauwolscine. In contrast to the high affinity observed with I and II, the corresponding derivatives of YOH exhibited 15 to 100-fold lower affinity. Iodination of I yields a radioligand (2175Ci/mmol) of high-affinity (K/sub D/ = 600pM) at the renal ..cap alpha../sub 2/-R and this compound should prove useful in biochemical studies of this ..cap alpha..-adrenergic receptor subtype. These data indicate that the spatial orientation of the aminophenyl substituent is an important determinant of high-affinity binding at ..cap alpha../sub 2/-R.

  7. Adrenergic receptor subtypes in the cerebral circulation of newborn piglets

    SciTech Connect

    Wagerle, L.C.; Delivoria-Papadopoulos, M.

    1987-06-01

    The purpose of this study was to identify the ..cap alpha..-adrenergic receptor subtype mediating cerebral vasoconstriction during sympathetic nerve stimulation in the newborn piglet. The effect of ..cap alpha../sub 1/- and ..cap alpha../sub 2/-antagonists prazosin and yohimbine on the cerebrovascular response to unilateral electrical stimulation (15 Hz, 15 V) of the superior cervical sympathetic trunk was studied in 25 newborn piglets. Regional cerebral blood flow was measured with tracer microspheres. Sympathetic stimulation decreased blood flow to the ipsilateral cerebrum hippocampus, choroid plexus, and masseter muscle. ..cap alpha../sub 1/-Adrenergic receptor blockade with prazosin inhibited the sympathetic vasoconstriction in the cerebrum, hippocampus, and masseter muscle and abolished it in the choroid plexus. ..cap alpha../sub s/-Adrenergic receptor blockade with yohimbine had no effect. Following the higher dose of yohimbine, however, blood flow to all brain regions was increased by approximately two-fold, possibly due to enhanced cerebral metabolism. These data demonstrate that vascular ..cap alpha../sub 1/-adrenergic receptors mediate vasoconstriction to neuroadrenergic stimulation in cerebral resistance vessels in the newborn piglet.

  8. cap alpha. -2 adrenergic receptor: a radiohistochemical study

    SciTech Connect

    Unnerstall, J.R.

    1984-01-01

    ..cap alpha..-2 adrenergic agents have been shown to influence blood pressure, heart rate and other physiological and behavioral functions through interactions with adrenergic pathways within the central nervous system. Pharmacologically relevant ..cap alpha..-1 adrenergic receptors were biochemically characterized and radiohistochemically analyzed in intact tissue sections of the rat and human central nervous system. The anatomical distribution of the ..cap alpha..-2 receptors, labeled with the agonist (/sup 3/H)para-aminoclonidine, verified the concept that ..cap alpha..-2 receptors are closely associated with adrenergic nerve terminals and that ..cap alpha..-2 agents can influence autonomic and endocrine function through an action in the central nervous system. Since ..cap alpha..-2 agonists can influence sympathetic outflow, ..cap alpha..-2 binding sites were closely analyzed in the intermediolateral cell column of the thoracic spinal cord. The transport of putative presynaptic ..cap alpha..-2 binding sites in the rat sciatic nerve was analyzed by light microscopic radiohistochemical techniques. Finally, in intact tissue section of the rat central nervous system, the biochemical characteristics of (/sup 3/H)rauwolscine binding were analyzed. Data were also shown which indicates that the synthetic ..cap alpha..-2 antagonist (/sup 3/H)RX781094 also binds to ..cap alpha..-2 receptors with high-affinity. Further, the distribution of (/sup 3/H)RX781094 binding sites in the rat central nervous system was identical to the distribution seen when using (/sup 3/H)para-aminoclonidine.

  9. Alpha 2-adrenergic receptor turnover in adipose tissue and kidney: irreversible blockade of alpha 2-adrenergic receptors by benextramine

    SciTech Connect

    Taouis, M.; Berlan, M.; Lafontan, M.

    1987-01-01

    The recovery of post- and extrasynaptic alpha 2-adrenergic receptor-binding sites was studied in vivo in male golden hamsters after treatment with an irreversible alpha-adrenoceptor antagonist benextramine, a tetramine disulfide that possesses a high affinity for alpha 2-binding sites. The kidney alpha 2-adrenergic receptor number was measured with (/sup 3/H)yohimbine, whereas (/sup 3/H)clonidine was used for fat cell and brain membrane alpha 2-binding site identification. Benextramine treatment of fat cell, kidney, and brain membranes reduced or completely suppressed, in an irreversible manner, (/sup 3/H) clonidine and (/sup 3/H)yohimbine binding without modifying adenosine (A1-receptor) and beta-adrenergic receptor sites. This irreversible binding was also found 1 and 2 hr after intraperitoneal administration of benextramine to the hamsters. Although it bound irreversibly to peripheral and central alpha 2-adrenergic receptors on isolated membranes, benextramine was unable to cross the blood-brain barrier of the hamster at the concentrations used (10-20 mg/kg). After the irreversible blockade, alpha 2-binding sites reappeared in kidney and adipose tissue following a monoexponential time course. Recovery of binding sites was more rapid in kidney than in adipose tissue; the half-lives of the receptor were 31 and 46 hr, respectively in the tissues. The rates of receptor production were 1.5 and 1.8 fmol/mg of protein/hr in kidney and adipose tissue. Reappearance of alpha 2-binding sites was associated with a rapid recovery of function (antilipolytic potencies of alpha 2-agonists) in fat cells inasmuch as occupancy of 15% of (/sup 3/H)clonidine-binding sites was sufficient to promote 40% inhibition of lipolysis. Benextramine is a useful tool to estimate turnover of alpha 2-adrenergic receptors under normal and pathological situations.

  10. Vasopressin receptor antagonists.

    PubMed

    Palmer, Biff F

    2015-01-01

    Arginine vasopressin (AVP) is the principal hormone involved in regulating the tonicity of body fluids. Less appreciated is the role that AVP plays in a variety of other physiologic functions including glucose metabolism, cardiovascular homeostasis, bone metabolism, and cognitive behavior. AVP receptor antagonists are now available and currently approved to treat hyponatremia. There is a great deal of interest in exploring the potential benefits that these drugs may play in blocking AVP-mediated effects in other organ systems. The purpose of this report is to provide an update on the expanding role of AVP receptor antagonists and what disease states these drugs may eventually be used for. PMID:25604388

  11. Selective β2-adrenergic Antagonist Butoxamine Reduces Orthodontic Tooth Movement

    PubMed Central

    Sato, T.; Miyazawa, K.; Suzuki, Y.; Mizutani, Y.; Uchibori, S.; Asaoka, R.; Arai, M.; Togari, A.; Goto, S.

    2014-01-01

    Recently, involvement of the sympathetic nervous system in bone metabolism has attracted attention. β2-Adrenergic receptor (β2-AR) is presented on osteoblastic and osteoclastic cells. We previously demonstrated that β-AR blockers at low dose improve osteoporosis with hyperactivity of the sympathetic nervous system via β2-AR blocking, while they may have a somewhat inhibitory effect on osteoblastic activity at high doses. In this study, the effects of butoxamine (BUT), a specific β2-AR antagonist, on tooth movement were examined in spontaneously hypertensive rats (SHR) showing osteoporosis with hyperactivity of the sympathetic nervous system. We administered BUT (1 mg/kg) orally, and closed-coil springs were inserted into the upper-left first molar. After sacrifice, we calculated the amount of tooth movement and analyzed the trabecular microarchitecture and histomorphometry. The distance in the SHR control was greater than that in the Wistar-Kyoto rat group, but no significant difference was found in the SHR treated with BUT compared with the Wistar-Kyoto rat control. Analysis of bone volume per tissue volume, trabecular number, and osteoclast surface per bone surface in the alveolar bone showed clear bone loss by an increase of bone resorption in SHR. In addition, BUT treatment resulted in a recovery of alveolar bone loss. Furthermore, TH-immunoreactive nerves in the periodontal ligament were increased by tooth movement, and BUT administration decreased TH-immunoreactive nerves. These results suggest that BUT prevents alveolar bone loss and orthodontic tooth movement via β2-AR blocking. PMID:24868013

  12. Characterization of. cap alpha. /sub 2/-adrenergic receptors in rat cerebral cortex

    SciTech Connect

    Nasseri, A.

    1987-01-01

    The properties of /sup 3/H-RX 781094 binding sites and the receptors inhibiting norepinephrine (NE) release and cyclic AMP accumulation in rat cerebral cortex were compared. /sup 3/H-RX 781094, a new ..cap alpha../sub 2/-adrenergic receptor antagonist radioligand, labelled a homogeneous population of binding sites at 37/sup 0/C with the pharmacological specificity expected of ..cap alpha../sub 2/-adrenergic receptors. Gpp(NH)p and NaCl decreased the potencies of agonists at /sup 3/H-RX 781094 binding sites 3-22 fold. Antagonists blocked the inhibition of potassium-evoked tritium release from cortical slices preloaded with /sup 3/H-NE by exogenous NE with potencies similar to those observed in competition for specific /sup 3/H-RX 781094 binding sites. EEDQ, an irreversible ..cap alpha../sub 2/-adrenergic receptors and determine whether there was a receptor reserve for the inhibition of tritium release.

  13. Selective orexin receptor antagonists.

    PubMed

    Lebold, Terry P; Bonaventure, Pascal; Shireman, Brock T

    2013-09-01

    The orexin, or hypocretin, neuropeptides (orexin-A and orexin-B) are produced on neurons in the hypothalamus which project to key areas of the brain that control sleep-wake states, modulation of food intake, panic, anxiety, emotion, reward and addictive behaviors. These neuropeptides exert their effects on a pair of G-protein coupled receptors termed the orexin-1 (OX1) and orexin-2 (OX2) receptors. Emerging biology suggests the involvement of these receptors in psychiatric disorders as they are thought to play a key role in the regulation of multiple systems. This review is intended to highlight key selective OX1 or OX2 small-molecule antagonists. PMID:23891187

  14. Xanthines as Adenosine Receptor Antagonists

    PubMed Central

    Jacobson, Kenneth A.

    2013-01-01

    The natural plant alkaloids caffeine and theophylline were the first adenosine receptor (AR) antagonists described in the literature. They exhibit micromolar affinities and are non-selective. A large number of derivatives and analogs have subsequently been synthesized and evaluated as AR antagonists. Very potent antagonists have thus been developed with selectivity for each of the four AR subtypes. PMID:20859796

  15. Species differences in the localization and number of CNS beta adrenergic receptors: Rat versus guinea pig

    SciTech Connect

    Booze, R.M.; Crisostomo, E.A.; Davis, J.N.

    1989-06-01

    The localization and number of beta adrenergic receptors were directly compared in the brains of rats and guinea pigs. The time course of association and saturability of (125I)cyanopindolol (CYP) binding to slide-mounted tissue sections was similar in rats (Kd = 17 pM) and guinea pigs (Kd = 20 pM). The beta-1 and beta-2 receptor subtypes were examined through the use of highly selective unlabeled receptor antagonists, ICI 118,551 (50 nM) and ICI 89,406 (70 nM). Dramatic species differences between rats and guinea pigs were observed in the neuroanatomical regional localization of the beta adrenergic receptor subtypes. For example, in the thalamus prominent beta-1 and beta-2 receptor populations were identified in the rat; however, the entire thalamus of the guinea pig had few, if any, beta adrenergic receptors of either subtype. Hippocampal area CA1 had high levels of beta-2 adrenergic receptors in both rats and guinea pigs but was accompanied by a widespread distribution of beta-2 adrenergic receptors only in rats. Quantitative autoradiographic analyses of 25 selected neuroanatomical regions (1) confirmed the qualitative differences in CNS beta adrenergic receptor localization, (2) determined that guinea pigs had significantly lower levels of beta adrenergic receptors than rats and (3) indicated a differential pattern of receptor subtypes between the two species. Knowledge of species differences in receptor patterns may be useful in designing effective experiments as well as in exploring the relationships between receptor and innervation patterns. Collectively, these data suggest caution be used in extrapolation of the relationships of neurotransmitters and receptors from studies of a single species.

  16. Quantitative autoradiography of. beta. /sub 1/- and. beta. /sub 2/-adrenergic receptors in rat brain

    SciTech Connect

    Rainbow, T.C.; Parsons, B.; Wolfe, B.B.

    1984-03-01

    The authors used quantitative autoradiography to localize in rat brain ..beta../sub 1/- and ..beta../sub 2/-adrenergic receptors. These receptors were labeled in vitro with /sup 125/I-labeled pindolol, an antagonist of ..beta..-adrenergic receptors that binds nonselectively to both ..beta../sub 1/ and ..beta../sub 2/ subtypes. The selective inhibition of /sup 125/I-labeled pindolol binding with specific antagonists of ..beta../sub 1/ and ..beta../sub 2/ receptors allowed the visualization of ..beta..-adrenergic receptor subtypes. High levels of ..beta../sub 1/ receptors were observed in the cingulate cortex, layers I and II of the cerebral cortex, the hippocampus, the Islands of Calleja, and the gelatinosus, mediodorsal, and ventral nuclei of the thalamus. High levels of ..beta../sub 2/ receptors were found in the molecular layer of the cerebellum, over pia mater, and in the central, paraventricular, and caudal lateral posterior thalamic nuclei. Approximately equal levels of ..beta../sub 1/ and ..beta../sub 2/ receptors occurred in the substantia nigra, the olfactory tubercle, layer IV of the cerebral cortex, the medial preoptic nucleus, and all nuclei of the medulla. The pronounced differences in the ratio of ..beta../sub 1/ to ..beta../sub 2/ receptors among brain regions suggests that the subtypes of ..beta..-adrenergic receptors may play different roles in neuronal function. 38 references, 3 figures, 1 table.

  17. Effect of age on upregulation of the cardiac adrenergic beta receptors

    SciTech Connect

    Tumer, N.; Houck, W.T.; Roberts, J.

    1990-03-01

    Radioligand binding studies were performed to determine whether upregulation of postjunctional beta receptors occurs in sympathectomized hearts of aged animals. Fischer 344 rats 6, 12, and 24 months of age (n = 10) were used in these experiments. To produce sympathectomy, rats were injected with 6-hydroxydopamine hydrobromide (6-OHDA; 2 x 50 mg/kg iv) on days 1 and 8; the animals were decapitated on day 15. The depletion of norepinephrine in the heart was about 86% in each age group. 125I-Iodopindolol (IPIN), a beta adrenergic receptor antagonist, was employed to determine the affinity and total number of beta adrenergic receptors in the ventricles of the rat heart. The maximal number of binding sites (Bmax) was significantly elevated by 37%, 48%, and 50% in hearts from sympathectomized 6-, 12-, and 24-month-old rats, respectively. These results indicate that beta receptor mechanisms in older hearts can respond to procedures that cause upregulation of the beta adrenergic receptors.

  18. The adrenergic receptor subtypes present in frog (Rana esculenta) skin.

    PubMed

    Bellantuono, Vito; Cassano, Giuseppe; Lippe, Claudio

    2008-08-01

    Frog skin transports ions and water under hormonal control. In spite of the fundamental role played by adrenergic stimulation in maintaining the water balance of the organism, the receptor subtype(s) present in the skin have not been identified yet. We measured the increase in short-circuit current (ISC, an estimate of ion transport) induced by cirazoline, clonidine, xamoterol, formoterol, or BRL 37344, in order to verify the presence of alpha1, alpha2, beta1, beta2, or beta3 receptor subtypes, respectively. Only after treatment with formoterol, BRL 37344 and, to a lesser extent, cirazoline was measured a significant increase in ISC (57%, 33.2%, and 4.7%, respectively). The formoterol and BRL 37344 concentrations producing half-maximal effect (EC50) were 1.12 and 70.1 nM, respectively. Moreover, the formoterol effect was inhibited by treatment with ICI 118551 (antagonist of beta2 receptors) while SR 59230A (antagonist of beta3 receptors) had no effect; opposite findings were obtained when the BRL 37344 stimulation was investigated. Finally, by measuring the transepithelial fluxes of 22Na+ and 36Cl-, we demonstrated that Na+ absorption is increased by activation of beta2 and beta3 and is cAMP-sensitive, whereas the Cl- secretion is only increased by activation of beta2 receptors and is cAMP- and calmodulin-sensitive. PMID:18544474

  19. Structure-guided development of dual β2 adrenergic/dopamine D2 receptor agonists.

    PubMed

    Weichert, Dietmar; Stanek, Markus; Hübner, Harald; Gmeiner, Peter

    2016-06-15

    Aiming to discover dual-acting β2 adrenergic/dopamine D2 receptor ligands, a structure-guided approach for the evolution of GPCR agonists that address multiple targets was elaborated. Starting from GPCR crystal structures, we describe the design, synthesis and biological investigation of a defined set of compounds leading to the identification of the benzoxazinone (R)-3, which shows agonist properties at the adrenergic β2 receptor and substantial G protein-promoted activation at the D2 receptor. This directed approach yielded molecular probes with tuned dual activity. The congener desOH-3 devoid of the benzylic hydroxyl function was shown to be a β2 adrenergic antagonist/D2 receptor agonist with Ki values in the low nanomolar range. The compounds may serve as a promising starting point for the investigation and treatment of neurological disorders. PMID:27132867

  20. Phosphoinositide metabolism and adrenergic receptors in astrocytes

    SciTech Connect

    Noble, E.P.; Ritchie, T.; de Vellis, J.

    1986-03-01

    Agonist-induced phosphoinositide (PI) breakdown functions as a signal generating system. Diacylglycerol, one breakdown product of phosphotidylinositol-4,5-diphosphate hydrolysis, can stimulate protein kinase C, whereas inositol triphosphate, the other product, has been proposed to be a second messenger for Ca/sup + +/ mobilization. Using purified astrocyte cultures from neonatal rat brain, the effects of adrenergic agonists and antagonists at 10/sup -5/ M were measured on PI breakdown. Astrocytes grown in culture were prelabeled with (/sup 3/H)inositol, and basal (/sup 3/H) inositol phosphate (IP/sub 1/) accumulation was measured in the presence of Li/sup +/. Epinephrine > norepinephrine (NE) were the most active stimulants of IP/sub 1/ production. The ..cap alpha../sub 1/ adrenoreceptor blockers, phentolamine and phenoxybenzamine, added alone had no effect on IP/sub 1/ production was reduced below basal levels. Propranolol partially blocked the effects of NE. Clonidine and isoproterenol, separately added, reduced IP/sub 1/ below basal levels and when added together diminished IP/sub 1/ accumulation even further. The role of adrenergic stimulation in the production of c-AMP.

  1. A sensitive equilibrium binding assay for soluble beta-adrenergic receptors

    SciTech Connect

    Witkin, K.M.; Harden, T.K.

    1981-01-01

    An equilibrium binding assay has been developed for digitonin-solubilized beta-adrenergic receptors using 125 I-pindolol (IPIN) as a radioligand. Up to 50% of the beta-adrenergic receptors from rat lung membranes could be solubilized using 1% digitonin. Following incubation of soluble fractions with IPIN at 25 degree, protein associated radioactivity was identified by column chromatography using Sephadex G-50. The solubilized receptors bound IPIN with properties similar but not identical to those of the membrane bound receptor. The Kd determined for IPIN binding to soluble receptors was 113 pM while the Kd for membrane associated receptors was 36 pM. The rate constant for association (k1) of IPIN was 0.15x10(9) M-1 for soluble receptors and 2.2x10(9) M-1 min-1 for lung membrane receptors. The rate constant for dissociation (k2) was 0.025 min-1 for soluble receptors and 0.048 min-1 for membrane receptors. Agonists and antagonist of beta-adrenergic receptors inhibited in a stereoselective manner the binding of IPIN to both soluble and membrane bound receptors. The affinities of individual drugs determined for soluble receptors were similar to those determined for membrane receptors. Not only could digitonin-solubilized receptors be identified in soluble preparations from rat lung, but also from rat cerebral cortex and liver, and from L6 muscle, C6 rat glioma, and 1321N1 astrocytoma cell membranes.

  2. Adrenergic receptors in human fetal liver membranes

    SciTech Connect

    Falkay, G.; Kovacs, L. )

    1990-01-01

    The adrenergic receptor binding capacities in human fetal and adult livers were measured to investigate the mechanism of the reduced alpha-1 adrenoreceptor response of the liver associated with a reciprocal increase in beta-adrenoreceptor activity in a number of conditions. Alpha-1 and beta-adrenoreceptor density were determined using {sup 3}H-prazosin and {sup 3}H-dihydroalprenolol, respectively, as radioligand. Heterogeneous populations of beta-adrenoreceptors were found in fetal liver contrast to adult. Decreased alpha-1 and increased beta-receptor density were found which may relate to a decreased level in cellular differentiation. These findings may be important for the investigation of perinatal hypoglycemia of newborns after treatment of premature labor with beta-mimetics. This is the first demonstration of differences in the ratio of alpha-1 and beta-adrenoceptors in human fetal liver.

  3. Competitive receptor binding radioassay for US -1 and US -2 adrenergic agents

    SciTech Connect

    Hussain, M.N.; Culbreth, W.; Dalrymple, R.; Fung, C.; Ricks, C.

    1987-05-01

    A rapid and sensitive competitive receptor bonding assay for US -1 and US -2 adrenergic binding for adrenergic agents has been developed. The steps that are critical for the success of the assay are given in detail so that the assay can be set up in any routine laboratory with relative ease. The rationale behind the use of specific reagents is discussed. The assay requires microgram quantities of test compound, a radiolabeled specific US adrenergic antagonist (TH)dihydroalprenolol (DHA), and turkey erythrocyte US -1 and rat erythrocyte US -2 receptor membranes. Serial dilutions of sample are incubated with appropriate receptor membranes and DHA for 1 hr at room temperature. After equilibrium is attained, the bound radioligand is separated by rapid filtration under vacuum through Whatman GF/B filters. The amount of bound DHA trapped on the filter is inversely proportional to the degree of US -1 and US -2 adrenergic binding of the sample. Separation of bound from free radioligand by filtration permits rapid determination of a large number of samples. This assay quantitates and differentiates US -1 and US -2 adrenergic binding of synthetic adrenergic agents.

  4. Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for alpha 2-adrenergic receptors

    SciTech Connect

    Lanier, S.M.; Graham, R.M.; Hess, H.J.; Grodski, A.; Repaske, M.G.; Nunnari, J.M.; Limbird, L.E.; Homcy, C.J.

    1987-06-01

    The selective alpha 2-adrenergic receptor antagonist rauwolscine was structurally modified to yield a series of arylamine carboxamide derivatives, which were investigated as potential molecular probes for the localization and structural characterization of alpha 2-adrenergic receptors. The arylamine carboxamides differ in the number of carbon atoms separating the reactive phenyl moiety from the fused ring structure of the parent compound, rauwolscine carboxylate. Competitive inhibition studies with (/sup 3/H)rauwolscine in rat kidney membranes indicate that the affinity for the carboxamide derivatives is inversely related to the length of the carbon spacer arm with rauwolscine 4-aminophenyl carboxamide exhibiting the highest affinity (Kd = 2.3 +/- 0.2 nM). Radioiodination of rau-AMPC yields a ligand, /sup 125/I-rau-AMPC, which binds to rat kidney alpha 2-adrenergic receptors with high affinity, as determined by both kinetic analysis (Kd = k2/k1 = 0.016 min-1/2.1 X 10(7) M-1 min-1 = 0.76 nM) and equilibrium binding studies (Kd = 0.78 +/- 0.16 nM). /sup 125/I-rau-AMPC was quantitatively converted to the photolabile arylazide derivative 17 alpha-hydroxy-20 alpha-yohimban-16 beta-(N-4-azido-3-(/sup 125/I)iodophenyl) carboxamide (/sup 125/I-rau-AZPC). In a partially purified receptor preparation from porcine brain, this compound photolabels a major (Mr = 62,000) peptide. The labeling of this peptide is inhibited by adrenergic agonists and antagonists with a rank order of potency consistent with an alpha 2-adrenergic receptor binding site. Both /sup 125/I-rau-AMPC and the photolabile arylazide derivative, /sup 125/I-rau-AZPC, should prove useful as molecular probes for the structural and biochemical characterization of alpha 2-adrenergic receptors.

  5. Pharmacological insight into neurotransmission origins of resting-state functional connectivity: α2-adrenergic agonist vs antagonist.

    PubMed

    Nasrallah, Fatima A; Low, Si-Min Amanda; Lew, Si Kang; Chen, Kaina; Chuang, Kai-Hsiang

    2014-12-01

    Resting-state functional connectivity MRI has emerged as a powerful tool for mapping large-scale neural networks based on synchronous BOLD signal; however, the neurobiological mechanisms are still unknown. To understand its neural substrates, especially the underlying neurotransmission, we applied pharmacological modulation with a receptor specific agonist and antagonist. Resting and evoked electrophysiology and BOLD signals in rat brains were measured under infusion of α2-adrenergic receptor agonist, medetomidine, the antagonist, atipamezole, and the vehicle individually. Both somatosensory BOLD activation and evoked potential were increased significantly under medetomidine compared to the vehicle while atipamezole slightly decreased both. The interhemispheric correlation at the resting state, in contrast, was suppressed by medetomidine but increased by atipamezole in regions with high receptor densities including the somatosensory cortex and thalamus. No change was seen in the caudate putamen, where receptor occupancy is low. The regional difference in connectivity was not related to cerebral blood flow, indicating that BOLD signal correlation is unlikely due to the vascular effects of the drugs. Resting intracortical recording exhibited agonist/antagonist dependent changes in beta and gamma bands that correlated with the BOLD functional connectivity measure. Our results confirm an important role of the adrenergic system on functional connectivity and suggest a neurotransmission basis of the phenomenon. PMID:25241086

  6. Stimulation of postsynapse adrenergic α2A receptor improves attention/cognition performance in an animal model of attention deficit hyperactivity disorder.

    PubMed

    Kawaura, Kazuaki; Karasawa, Jun-ichi; Chaki, Shigeyuki; Hikichi, Hirohiko

    2014-08-15

    A 5-trial inhibitory avoidance test using spontaneously hypertensive rat (SHR) pups has been used as an animal model of attention deficit hyperactivity disorder (ADHD). However, the roles of noradrenergic systems, which are involved in the pathophysiology of ADHD, have not been investigated in this model. In the present study, the effects of adrenergic α2 receptor stimulation, which has been an effective treatment for ADHD, on attention/cognition performance were investigated in this model. Moreover, neuronal mechanisms mediated through adrenergic α2 receptors were investigated. We evaluated the effects of both clonidine, a non-selective adrenergic α2 receptor agonist, and guanfacine, a selective adrenergic α2A receptor agonist, using a 5-trial inhibitory avoidance test with SHR pups. Juvenile SHR exhibited a shorter transfer latency, compared with juvenile Wistar Kyoto (WKY) rats. Both clonidine and guanfacine significantly prolonged the transfer latency of juvenile SHR. The effects of clonidine and guanfacine were significantly blocked by pretreatment with an adrenergic α2A receptor antagonist. In contrast, the effect of clonidine was not attenuated by pretreatment with an adrenergic α2B receptor antagonist, or an adrenergic α2C receptor antagonist, while it was attenuated by a non-selective adrenergic α2 receptor antagonist. Furthermore, the effects of neither clonidine nor guanfacine were blocked by pretreatment with a selective noradrenergic neurotoxin. These results suggest that the stimulation of the adrenergic α2A receptor improves the attention/cognition performance of juvenile SHR in the 5-trial inhibitory avoidance test and that postsynaptic, rather than presynaptic, adrenergic α2A receptor is involved in this effect. PMID:24882610

  7. A nuclear pathway for alpha 1-adrenergic receptor signaling in cardiac cells.

    PubMed Central

    Ardati, A; Nemer, M

    1993-01-01

    alpha 1-Adrenergic agonists and antagonists constitute an important class of therapeutic agents commonly used for the treatment of various cardiovascular diseases like hypertension, congestive heart failure and supraventricular tachycardia. At the heart level, activation of alpha 1-adrenergic receptors is associated with marked morphological and genetic changes. These include enhancement of contractility, myocardial growth (hypertrophy) and release of the heart major secretory product, atrial natriuretic factor (ANF). However, the signal transduction pathways which link extracellular activation of the receptors to cellular and genetic changes are not well understood. Using primary cardiocyte cultures from neonate rat hearts, an alpha 1-adrenergic regulatory sequence has been identified in the 5' flanking region of the ANF gene. This sequence, which is necessary and sufficient for transcriptional activation in response to the alpha 1-specific agonist phenylephrine, interacts with novel zinc-dependent proteins which are induced by alpha 1-adrenergic stimulation. Consistent with a conserved regulatory mechanism, the alpha 1 response element is highly conserved between rodent, bovine and human ANF genes, and is also present in the promoter region of other alpha 1-responsive cardiac genes. The identification of a nuclear pathway for alpha 1-receptor signaling will be useful for elucidating the intracellular effectors of alpha 1-adrenergic receptors. Images PMID:8262057

  8. Impact of the Tamsulosin in Alpha Adrenergic Receptor of Airways at Patients with Increased Bronchial Reactibility

    PubMed Central

    Mustafa, Lirim; Ilazi, Ali; Dauti, Arta; Islami, Pellumb; Kastrati, Bashkim; Islami, Hilmi

    2015-01-01

    Objective: In this work, effect of tamsulosin as antagonist of alpha1A and alpha1B adrenergic receptor and effect of agonists of beta2 adrenergic receptor–salbutamol in patients with increased bronchial reactibility was studied. Methods: Parameters of the lung function are determined with Body plethysmography six (6) hours after administration of tamsulosin. Raw and ITGV were registered and specific resistance (SRaw) was calculated as well. Tamsulosin was administered in per os manner as a preparation in the shape of the capsules with a brand name of “Prolosin”, produced by Niche Generics Limited, Hitchin, Herts. Results: After six (6) hours of administration of tamsulosin, results gained indicate that blockage of alpha1A and alpha1B-adrenergic receptor (0.8 mg per os) has not changed significantly (p > 0.1) the bronchomotor tonus of tracheobronchial tree in comparison to the check-up that has inhaled salbutamol agonist of adrenergic beta2 receptor (2 inh. x 0.2 mg), (p < 0.05). Blood pressure suffered no significant decrease following administration of the 0.8 mg dose of tamsulosin. Conclusion: This suggests that even after six hours of administration of tamsulosin, and determining of lung function parameters, the activity of alpha1A and alpha1B-adrenergic receptor in the smooth bronchial musculature has not changed in patients with increased bronchial reactibility. PMID:26543414

  9. Beta(2)-adrenergic receptor regulates cardiac fibroblast autophagy and collagen degradation.

    PubMed

    Aránguiz-Urroz, Pablo; Canales, Jimena; Copaja, Miguel; Troncoso, Rodrigo; Vicencio, Jose Miguel; Carrillo, Constanza; Lara, Hernán; Lavandero, Sergio; Díaz-Araya, Guillermo

    2011-01-01

    Autophagy is a physiological degradative process key to cell survival during nutrient deprivation, cell differentiation and development. It plays a major role in the turnover of damaged macromolecules and organelles, and it has been involved in the pathogenesis of different cardiovascular diseases. Activation of the adrenergic system is commonly associated with cardiac fibrosis and remodeling, and cardiac fibroblasts are key players in these processes. Whether adrenergic stimulation modulates cardiac fibroblast autophagy remains unexplored. In the present study, we aimed at this question and evaluated the effects of b(2)-adrenergic stimulation upon autophagy. Cultured adult rat cardiac fibroblasts were treated with agonists or antagonists of beta-adrenergic receptors (b-AR), and autophagy was assessed by electron microscopy, GFP-LC3 subcellular distribution, and immunowesternblot of endogenous LC3. The predominant expression of b(2)-ARs was determined and characterized by radioligand binding assays using [(3)H]dihydroalprenolol. Both, isoproterenol and norepinephrine (non-selective b-AR agonists), as well as salbutamol (selective b(2)-AR agonist) increased autophagic flux, and these effects were blocked by propanolol (b-AR antagonist), ICI-118,551 (selective b(2)-AR antagonist), 3-methyladenine but not by atenolol (selective b(1)-AR antagonist). The increase in autophagy was correlated with an enhanced degradation of collagen, and this effect was abrogated by the inhibition of autophagic flux. Overall, our data suggest that b(2)-adrenergic stimulation triggers autophagy in cardiac fibroblasts, and that this response could contribute to reduce the deleterious effects of high adrenergic stimulation upon cardiac fibrosis. PMID:20637865

  10. Identification of alpha 2-adrenergic receptor sites in human retinoblastoma (Y-79) and neuroblastoma (SH-SY5Y) cells

    SciTech Connect

    Kazmi, S.M.; Mishra, R.K.

    1989-02-15

    The existence of specific alpha 2-adrenergic receptor sites has been shown in human retinoblastoma (Y-79) and neuroblastoma (SH-SH5Y) cells using direct radioligand binding. (/sup 3/H)Rauwolscine, a selective alpha 2-adrenergic receptor antagonist, exhibited high affinity, saturable binding to both Y-79 and SH-SY5Y cell membranes. The binding of alpha 1 specific antagonist, (/sup 3/H)Prazocine, was not detectable in either cell type. Competition studies with antagonists yielded pharmacological characteristics typical of alpha 2-adrenergic receptors: rauwolscine greater than yohimbine greater than phentolamine greater than prazocine. Based on the affinity constants of prazocine and oxymetazoline, it appears that Y-79 cells contain alpha 2A receptor, whereas SH-SY5Y cells probably represent a mixture of alpha 2A and alpha 2B receptors. alpha 2-agonists clonidine and (-)epinephrine inhibition curves yielded high and low affinity states of the receptor in SH-SY5Y cells. Gpp(NH)p and sodium ions reduced the proportion of high affinity sites of alpha 2 receptors. These two neuronal cell lines of human origin would prove useful in elucidating the action and regulation of human alpha 2-adrenergic receptors and their interaction with other receptor systems.

  11. The adrenergic α2 antagonist atipamezole alters the behavioural effects of pramipexole and increases pramipexole concentration in blood plasma.

    PubMed

    McCormick, P N; Fletcher, P J; Wilson, V S; Remington, G J

    2016-04-15

    Pramipexole is a dopaminergic agonist used in Parkinson's disease treatment. It is thought to exert its therapeutic and side effects through actions on dopamine D3 receptors. In a recent study, we found that at doses occupying D3 but not D2 receptors pramipexole reduced locomotion and operant responding for primary and conditioned reinforcement. These effects, however, were not blocked by a D3 receptor antagonist and were present in D3 knockout mice, suggesting non-D3 receptor mechanisms. Among the next highest affinity binding sites of pramipexole are adrenergic α2 receptors. Here we explored α2 receptor involvement in the behavioural effects of pramipexole. We found that the α2 antagonist atipamezole, which was itself behaviourally silent, counteracted pramipexole's reduction of locomotion, but not operant responding for water or a conditioned reinforcer. The resulting behavioural profile was similar to that of a higher dose of pramipexole, leading to the hypothesize that atipamezole mediates its behavioural effects by increasing pramipexole effective dose. In support of this hypothesis, we found that atipamezole increased pramipexole concentration in blood plasma. This is not likely due to an effect on drug metabolism since pramipexole is not known to undergo metabolic transformation. Future work should examine two alternative hypotheses; that pramipexole plasma concentration is elevated as the result of 1) competition with atipamezole for renal excretion, or 2) atipamezole blockade of peripheral α2 binding sites, thereby preventing pramipexole distribution to α2-rich tissues. The suggestion of adrenergic effects of pramipexole is important in light of recent interest in adrenergic pathophysiology in Parkinson's disease. PMID:26976325

  12. Pharmacological Beta-Adrenergic Receptor Activation Attenuates Neutrophil Recruitment by a Mechanism Dependent on Nicotinic Receptor and the Spleen.

    PubMed

    Silva, Rangel L; Castanheira, Fernanda V; Figueiredo, Jozi G; Bassi, Gabriel S; Ferreira, Sérgio H; Cunha, Fernando Q; Cunha, Thiago M; Kanashiro, Alexandre

    2016-08-01

    The aim of this study was to identify the effect of beta-adrenergic receptor activation on neutrophil migration in experimental peritonitis elucidating the neuroimmune components involved such as nicotinic receptors and the spleen. Mice pre-treated with mecamylamine (nicotinic antagonist) and propranolol (beta-adrenergic antagonist) or splenectomized animals were treated with isoproterenol (beta-adrenergic agonist) prior to intraperitoneal injection of carrageenan. After 4 h, the infiltrating neutrophils and the local cytokine/chemokine levels were evaluated in the peritoneal lavage. The effect of isoproterenol on neutrophil chemotaxis was investigated in a Boyden chamber. Isoproterenol inhibited neutrophil trafficking, reducing the cytokine/chemokine release and neutrophil chemotaxis. Surprisingly, the isoproterenol effect on neutrophil migration was totally reverted by splenectomy and mecamylamine pre-treatment. In contrast, the inhibitory effect of nicotine on neutrophil migration was abrogated only by splenectomy but not by propranolol pre-treatment. Collectively, our data show that beta-adrenergic receptor activation regulates the acute neutrophil recruitment via splenic nicotinic receptor. PMID:27262431

  13. Astrocytic beta(2)-adrenergic receptors: from physiology to pathology.

    PubMed

    Laureys, Guy; Clinckers, Ralph; Gerlo, Sarah; Spooren, Anneleen; Wilczak, Nadine; Kooijman, Ron; Smolders, Ilse; Michotte, Yvette; De Keyser, Jacques

    2010-07-01

    Evidence accumulates for a key role of the beta(2)-adrenergic receptors in the many homeostatic and neuroprotective functions of astrocytes, including glycogen metabolism, regulation of immune responses, release of neurotrophic factors, and the astrogliosis that occurs in response to neuronal injury. A dysregulation of the astrocytic beta(2)-adrenergic-pathway is suspected to contribute to the physiopathology of a number of prevalent and devastating neurological conditions such as multiple sclerosis, Alzheimer's disease, human immunodeficiency virus encephalitis, stroke and hepatic encephalopathy. In this review we focus on the physiological functions of astrocytic beta(2)-adrenergic receptors, and their possible impact in disease states. PMID:20138112

  14. Amiloride interacts with renal. cap alpha. - and. beta. -adrenergic receptors

    SciTech Connect

    Howard, M.J.; Mullen, M.D.; Insel, P.A.

    1987-07-01

    The authors have used radioligand binding techniques to assess whether amiloride and certain analogues of amiloride (ethylisopropyl amiloride and benzamil) can bind to adrenergic receptors in the kidney. They found that amiloride could compete for (/sup 3/H)rauwolscine (..cap alpha../sub 2/-adrenergic receptors), (/sup 3/H)prazosin (..cap alpha../sub 1/-adrenergic receptors), and (/sup 125/I)iodocyanopindolol (..beta..-adrenergic receptors) binding in rat renal cortical membranes with inhibitor constants of 13.6 /plus minus/ 5.7, 24.4 /plus minus/ 7.4, and 8.36 /plus minus/ 13.5 ..mu..M, respectively. Ethylisopropyl amiloride and benzamil were from 2- to 25-fold more potent than amiloride in competing for radioligand binding sites in studies with these membranes. In addition, amiloride and the two analogues competed for (/sup 3/H)prazosin sites on intact Madin-Darby canine kidney cells and amiloride blocked epinephrine-stimulated prostaglandin E/sub 2/ production in these cells. They conclude that amiloride competes for binding to several classes of renal adrenergic receptors with a rank order of potency of ..cap alpha../sub 2/ > ..cap alpha../sub 1/ > ..beta... Binding to, and antagonism of, adrenergic receptors occurs at concentrations of amiloride that are lower than previously observed nonspecific interactions of this agent.

  15. Effects of β-adrenergic receptor agonists on drinking and arterial blood pressure in young and old rats

    PubMed Central

    Grobe, Connie L.; Beltz, Terry G.; Johnson, Alan Kim

    2011-01-01

    These experiments examined water-drinking and arterial blood pressure responses to β-adrenergic receptor activation in young (4 mo), “middle-aged” adult (12 mo), and old (29 mo) male rats of the Brown-Norway strain. We used isoproterenol to simultaneously activate β1- and β2-adrenergic receptors, salbutamol to selectively activate β2-adrenergic receptors, and the combination of isoproterenol and the β2-adrenergic receptor antagonist ICI 118,551 to stimulate only β1-adrenergic receptors. Animals received one of the drug treatments, and water drinking was measured for 90 min. About 1 wk later, animals received the same drug treatment for measurement of arterial blood pressure responses for 90 min. In some rats, levels of renin and aldosterone secretion in response to isoproterenol or salbutamol were measured in additional tests. Old and middle-aged rats drank significantly less after isoproterenol than did young rats and also had greater reductions in arterial blood pressure. Old and middle-aged rats drank significantly less after salbutamol than did young rats, although reductions in arterial blood pressure were equivalent across the ages. The β2-adrenergic antagonist ICI 118,551 abolished drinking after isoproterenol and prevented most of the observed hypotension. Renin secretion after isoproterenol and salbutamol was greater in young rats than in middle-aged rats, and wholly absent in old rats. Aldosterone secretion was reduced in old rats compared with young and middle-aged rats after treatment with isoproterenol, but not after treatment with salbutamol. In conclusion, there are age-related differences in β-adrenergic receptor-mediated drinking that can be explained only in part by age-related differences in renin secretion after β-adrenergic receptor stimulation. PMID:21307363

  16. Catechol-O-methyltransferase Inhibition Increases Pain Sensitivity through Activation of Both β2 and β3 Adrenergic Receptors

    PubMed Central

    Nackley-Neely, Andrea Gail; Tan, Kai Soo; Fecho, Karamarie; Flood, Patrick; Diatchenko, Luda; Maixner, William

    2007-01-01

    Catechol-O-methyltransferase (COMT), an enzyme that metabolizes catecholamines, has recently been implicated in the modulation of pain. Our group demonstrated that human genetic variants of COMT are predictive for the development of Temporomandibular Joint Disorder (TMJD) and are associated with heightened experimental pain sensitivity (Diatchenko et al. 2005). Variants associated with heightened pain sensitivity produce lower COMT activity. Here we report the mechanisms underlying COMT-dependent pain sensitivity. To characterize the means whereby elevated catecholamine levels, resulting from reduced COMT activity, modulate heightened pain sensitivity, we administered a COMT inhibitor to rats and measured behavioral responsiveness to mechanical and thermal stimuli. We show that depressed COMT activity results in enhanced mechanical and thermal pain sensitivity. This phenomenon is completely blocked by the nonselective β-adrenergic antagonist propranolol or by the combined administration of selective β2- and β3-adrenergic antagonists, while administration of β1-adrenergic, α-adrenergic, or dopaminergic receptor antagonists fail to alter COMT-dependent pain sensitivity. These data provide the first direct evidence that low COMT activity leads to increased pain sensitivity via a β2/3-adrenergic mechanism. These findings are of considerable clinical importance, suggesting that pain conditions resulting from low COMT activity and/or elevated catecholamine levels can be treated with pharmacological agents that block both β2- and β3-adrenergic receptors. PMID:17084978

  17. Autoradiographic quantification of adrenergic receptors in rat kidney

    SciTech Connect

    Calianos, T. II; Muntz, K.H. )

    1990-07-01

    The adrenergic nervous system is active in kidney function, and the kidney has large numbers of adrenergic receptor subtypes. Because of the cellular complexity of the kidney, it is difficult to obtain direct assessments of adrenergic receptor binding characteristics over specific tissue compartments. Qualitative autoradiography allows the localization of adrenergic receptors over tissue types in the kidney, but quantitative autoradiography allows direct comparison of adrenergic receptor number over different cellular compartments. The purpose of this study was to obtain direct assessments of alpha 1, alpha 2, and beta adrenergic receptor numbers over different tissue compartments of the kidney using quantitative autoradiography. Sections of Sprague-Dawley rat kidney were incubated in several concentrations of 3H-dihydroalprenolol to label beta receptors, 3H-prazosin to label alpha 1 receptors and 3H-rauwolscine to label the alpha 2 receptors. Sections of rat heart incubated in 3H-dihydroalprenolol were included as standards. The sections were then prepared for receptor autoradiography. After processing, the grains were then quantified on an image analysis system, and binding curves constructed from the specific binding. In some animals, the proximal tubules were stained to localize the proximal convoluted tubules. Significant Scatchard analyses were obtained in the glomeruli with dihydroalprenolol (5.18 X 10(9) receptors/mm3) and with rauwolscine (2.48 X 10(9) receptors/mm3). Significant Scatchard analyses were obtained in the cortex with rauwolscine (9.47 X 10(9) receptors/mm3) and with prazosin (3.9 X 10(9)). In addition, specific binding was seen with rauwolscine and prazosin to the kidney arterioles.

  18. Alpha-2 adrenergic and serotonin-1B receptors in the OK cell, an opossum kidney cell line

    SciTech Connect

    Murphy, T.J.

    1988-01-01

    Alpha-2 adrenergic and serotonin-1B (5HT{sub 1B}) receptors, both negatively-coupled to adenylyl cyclase, were characterized in the OK cell line, a renal proximal tubule epithelial cell line derived from the kidney of a North American opossum. In membrane saturation radioligand binding experiments, ({sup 3}H)yohimbine and ({sup 3}H)rauwolscine labeled an equivalent number of binding sites. Detailed pharmacological analysis of OK cell alpha-2 adrenergic receptors in competition binding assays indicate this receptor is neither an alpha-2A nor an alpha-2B adrenergic receptor subtype, although the alpha-2B receptor subtype-selective drugs prazosin, ARC-239 and chlorpromazine have affinities for OK cell alpha-2 adrenergic receptors similar to those at the alpha-2B receptor subtype. Determinations of agonist potency for inhibition of PTH-stimulated cyclic AMP production and radioligand binding analysis using ({sup 125}I)({minus})-cyanopindolol indicate that a 5HT{sub 1B} receptor is expressed in the OK cell line. A biochemical effector system coupled to this receptor subtype has not been previously described. Several compounds appear to be potent agonists at the 5TH{sub 1B} receptor including the beta adrenergic antagonists cyanopindolol, pindolol, propranolol and alprenolol.

  19. Characterization of beta-adrenergic receptors in dispersed rat testicular interstitial cells

    SciTech Connect

    Poyet, P.; Labrie, F.

    1987-01-01

    Recent studies have shown that beta-adrenergic agents stimulate steroidogenesis and cyclic AMP formation in mouse Leydig cells in culture. To obtain information about the possible presence and the characteristics of a beta-adrenergic receptor in rat testicular interstitial cells, the potent beta-adrenergic antagonist (/sup 125/I)cyanopindolol (CYP) was used as ligand. Interstitial cells prepared by collagenase dispersion from rat testis were incubated with the ligand for 2 h at room temperature. (/sup 125/I)cyanopindolol binds to a single class of high affinity sites at an apparent KD value of 15 pM. A number of sites of 6,600 sites/cell is measured when 0.1 microM (-) propranolol is used to determine non-specific binding. The order of potency of a series of agonists competing for (/sup 125/I)cyanopindolol binding is consistent with the interaction of a beta 2-subtype receptor: zinterol greater than (-) isoproterenol greater than (-) epinephrine = salbutamol much greater than (-) norepinephrine. In addition, it was observed that the potency of a large series of specific beta 1 and beta 2 synthetic compounds for displacing (/sup 125/I)cyanopindolol in rat interstitial cells is similar to the potency observed for these compounds in a typical beta 2-adrenergic tissue, the rat lung. For example, the potency of zinterol, a specific beta 2-adrenergic agonist, is 10 times higher in interstitial cells and lung than in rat heart, a typical beta 1-adrenergic tissue. Inversely, practolol, a typical beta 1-antagonist, is about 50 times more potent in rat heart than in interstitial cells and lung.

  20. β-Adrenergic receptor expression in vascular tumors.

    PubMed

    Chisholm, Karen M; Chang, Kay W; Truong, Mai T; Kwok, Shirley; West, Rob B; Heerema-McKenney, Amy E

    2012-11-01

    Propranolol has recently emerged as an effective therapy for infantile hemangiomas causing regression. The β-adrenergic receptor (AR) antagonist is thought to cause vasoconstriction by its effect on nitric oxide, block angiogenesis by its effect on vascular endothelial growth factor (VEGF), and induce apoptosis. In a prior report, we identified expression of β2-AR (B2-AR) and its phosphorylated form (B2-ARP) in a case of infantile hemangioma that responded to propranolol treatment. We now explore the expression of βARs on a variety of vascular lesions utilizing a tissue microarray containing 141 lesions, including infantile hemangiomas, angiosarcomas, hemangiomas, hemangioendotheliomas, and various vascular malformations. The array was immunostained for B2-AR, B2-ARP, and β3-AR (B3-AR), and the results scored for the intensity of endothelial cell expression as negative, weak positive, or strong positive. All phases of infantile hemangiomas had strong expression of all three receptors, with the exception of only weak expression of B2-ARP in the proliferative phase infantile hemangioma. Strong expression of all three receptors was present in many hemangiomas, hemangioendotheliomas, and vascular malformations. Absent to weak expression of all three receptors was seen in glomus tumor, hobnail hemangioendothelioma, pyogenic granuloma, and reactive vascular proliferations. This is the first study to report β-AR expression in a variety of vascular lesions. Although immunohistochemical expression of the receptors does not necessarily indicate that similar pathways of responsiveness to β-blockade are present, it does raises the possibility that β-blockade could potentially affect apoptosis and decrease responsiveness to VEGF. Additional study is warranted, as therapeutic options are limited for some patients with these lesions. PMID:22743651

  1. Alpha-1 adrenergic receptor: Binding and phosphoinositide breakdown in human myometrium

    SciTech Connect

    Breuiller-Fouche, M.; Doualla-Bell Kotto Maka, F.; Geny, B.; Ferre, F. )

    1991-07-01

    Alpha-1 adrenergic receptors were examined in both inner and outer layers of human pregnant myometrium using radioligand binding of (3H)prazosin. (3H)prazosin bound rapidly and reversibly to a single class of high affinity binding sites in myometrial membrane preparations. Scatchard analysis gave similar values of equilibrium dissociation constants in both myometrial layers. In contrast, more alpha-1 adrenergic receptors were detected in the outer layer than in the inner layer. Antagonist inhibited (3H)prazosin binding with an order of potency of prazosin greater than phentolamine greater than idazoxan. Competition experiments have also revealed that a stable guanine nucleotide decreases the apparent affinity of norepinephrine for myometrial (3H)prazosin binding sites. The functional status of these alpha-1 adrenergic receptors was also assessed by measuring the norepinephrine-induced accumulation of inositol phosphates in myometrial tissue. Norepinephrine produced a concentration-dependent accumulation of inositol phosphates in both myometrial layers. However, norepinephrine-induced increases in inositol 1,4,5-triphosphate were only observed in the outer layer. These results indicate that alpha-1 adrenergic receptors in human myometrium at the end of pregnancy are linked to phosphoinositide hydrolysis and that this response occurs mainly in the outer layer.

  2. Effects of halothane on the human beta-adrenergic receptor of lymphocyte membranes

    SciTech Connect

    Marty, J.; Nivoche, Y.; Nimier, M.; Rocchiccioli, C.; Luscombe, F.; Henzel, D.; Loiseau, A.; Desmonts, J.M.

    1987-12-01

    The effects of halothane on beta-adrenergic receptor antagonist interaction were studied using the membranes of human lymphocytes as a model. Membrane preparations of lymphocytes were obtained from blood samples withdrawn from seven healthy young volunteers. Beta-receptor studies were performed using (-)/sup 125/I iodocyanopindolol (/sup 125/ICP) binding. Non-specific binding was determined in the presence of (-)isoproterenol. Beta-receptor density (Bmax) and the dissociation constant (KD) for /sup 125/ICP were determined from saturation curves. Beta-receptor affinity for agonists evaluated by the IC50 (the concentration of isoproterenol required to inhibit 50% of specific /sup 125/ICP binding) and the dissociation constant (KL) for isoproterenol was established from competition curves. The effect of halothane 1%, in an air oxygen mixture (oxygen fraction: 0.3) administered by tonometry during ligand membrane incubation, on beta-adrenergic receptor, was compared to that of control experiments not exposed to halothane. Halothane produced a moderate but significant decrease of Bmax (-10%) and a significant increase in non-specific binding (+30%), while KD, IC50, and KL were unchanged. The authors conclude that halothane, in vitro, decreases beta-adrenergic receptor density. This effect could be mediated by an alteration of the receptor in the membrane due to action of halothane on the lipid phase of the membrane.

  3. β-Adrenergic Receptor Signaling in Prostate Cancer

    PubMed Central

    Braadland, Peder Rustøen; Ramberg, Håkon; Grytli, Helene Hartvedt; Taskén, Kristin Austlid

    2015-01-01

    Enhanced sympathetic signaling, often associated with obesity and chronic stress, is increasingly acknowledged as a contributor to cancer aggressiveness. In prostate cancer, intact sympathetic nerves are critical for tumor formation, and sympathectomy induces apoptosis and blocks tumor growth. Perineural invasion, involving enrichment of intra-prostatic nerves, is frequently observed in prostate cancer and is associated with poor prognosis. β2-adrenergic receptor (ADRB2), the most abundant receptor for sympathetic signals in prostate luminal cells, has been shown to regulate trans-differentiation of cancer cells to neuroendocrine-like cells and to affect apoptosis, angiogenesis, epithelial–mesenchymal transition, migration, and metastasis. Epidemiologic studies have shown that use of β-blockers, inhibiting β-adrenergic receptor activity, is associated with reduced prostate cancer-specific mortality. In this review, we aim to present an overview on how β-adrenergic receptor and its downstream signaling cascade influence the development of aggressive prostate cancer, primarily through regulating neuroendocrine differentiation. PMID:25629002

  4. Adrenal medullary regulation of rat renal cortical adrenergic receptors

    SciTech Connect

    Sundaresan, P.R.; Guarnaccia, M.M.; Izzo, J.L. Jr. )

    1987-11-01

    The role of the adrenal medulla in the regulation of renal cortical adrenergic receptors was investigated in renal cortical particular fractions from control rats and rats 6 wk after adrenal demedullation. The specific binding of ({sup 3}H)prazosin, ({sup 3}H)rauwolscine, and ({sup 125}I)iodocyanopindolol were used to quantitate {alpha}{sub 1}-, {alpha}{sub 2}-, and {beta}-adrenergic receptors, respectively. Adrenal demedullation increased the concentration of all three groups of renal adrenergic receptors; maximal number of binding sites (B{sub max}, per milligram membrane protein) for {alpha}{sub 1}-, and {alpha}{sub 2}-, and {beta}-adrenergic receptors were increased by 22, 18.5, and 25%, respectively. No differences were found in the equilibrium dissociation constants (K{sub D}) for any of the radioligands. Plasma corticosterone and plasma and renal norepinephrine levels were unchanged, whereas plasma epinephrine was decreased 72% by adrenal demedullation, renal cortical epinephrine was not detectable in control or demedullated animals. The results suggest that, in the physiological state, the adrenal medulla modulates the number of renal cortical adrenergic receptors, presumably through the actions of a circulating factor such as epinephrine.

  5. Non-co-ordinate development of beta-adrenergic receptors and adenylate cyclase in chick heart.

    PubMed Central

    Alexander, R W; Galper, J B; Neer, E J; Smith, T W

    1982-01-01

    We have studied the properties of beta-adrenergic receptors and of their interaction with adenylate cyclase in the chick myocardium during embryogenesis. Between 4.5 and 7.5 days in ovo the number of receptors determined by (-)-[3H]dihydroalprenolol ([3H]DHA) binding is constant at approx. 0.36 pmol of receptor/mg of protein. By day 9 the density decreases significantly to 0.22 pmol of receptor/mg of protein. At day 12.5--13.5 the number was 0.14--0.18 pmol of receptor/mg of protein. This number did not change further up to day 16. The same results were obtained with guanosine 5'-[beta, gamma-imido]triphosphate (p[NH]ppG) added to the assay mixtures. There was no significant change in receptor affinity for the antagonist [3H]DHA between days 5.5 and 13. Despite the decrease in numbers of beta-adrenergic receptors, there was no change in basal, p[NH]ppG-, isoprenaline- or isoprenaline-plus-p[NH]ppG-stimulated adenylate cyclase activity between days 3 and 12 of development. We conclude that beta-adrenergic receptors and adenylate cyclase are not co-ordinately regulated during early embryonic development of the chick heart. Some of the beta-adrenergic receptors present very early in the ontogeny of cardiac tissue appear not to be coupled to adenylate cyclase since their loss is not reflected in decreased activation of the enzyme. PMID:6289805

  6. Endothelin receptors and their antagonists.

    PubMed

    Maguire, Janet J; Davenport, Anthony P

    2015-03-01

    All three members of the endothelin (ET) family of peptides, ET-1, ET-2, and ET-3, are expressed in the human kidney, with ET-1 being the predominant isoform. ET-1 and ET-2 bind to two G-protein-coupled receptors, ETA and ETB, whereas at physiological concentrations ET-3 has little affinity for the ET(A) receptor. The human kidney is unusual among the peripheral organs in expressing a high density of ET(B). The renal vascular endothelium only expresses the ET(B) subtype and ET-1 acts in an autocrine or paracrine manner to release vasodilators. Endothelial ETB in kidney, as well as liver and lungs, also has a critical role in scavenging ET-1 from the plasma. The third major function is ET-1 activation of ET(B) in in the nephron to reduce salt and water re-absorption. In contrast, ET(A) predominate on smooth muscle, causing vasoconstriction and mediating many of the pathophysiological actions of ET-1. The role of the two receptors has been delineated using highly selective ET(A) (BQ123, TAK-044) and ET(B) (BQ788) peptide antagonists. Nonpeptide antagonists, bosentan, macitentan, and ambrisentan, that are either mixed ET(A)/ET(B) antagonists or display ET(A) selectivity, have been approved for clinical use but to date are limited to pulmonary hypertension. Ambrisentan is in clinical trials in patients with type 2 diabetic nephropathy. This review summarizes ET-receptor antagonism in the human kidney, and considers the relative merits of selective versus nonselective antagonism in renal disease. PMID:25966344

  7. The effect of alpha2-adrenergic receptors on cutaneous water evaporation in the rock pigeon (Columba livia).

    PubMed

    Ophir, Eshel; Arieli, Yehuda; Marder, Jacob

    2004-12-01

    The role of beta-adrenergic receptors in regulating cutaneous water evaporation (CWE) in the rock pigeon (Columba livia) is well documented. Here, we studied the involvement of the alpha2-adrenergic receptors in this cooling mechanism of the heat-acclimated (HAc) pigeon. Systemic alpha2-adrenergic activation [clonidine, 50 microg kg(-1), intramuscular (i.m.)] was found to increase CWE in heat-acclimated pigeons at an ambient temperature (T(a)) of 25 degrees C. Subcutaneous administration of the drug had no significant effect. Preinjection of an alpha2-adrenergic antagonist (yohimbine, 10 mg kg(-1), i.m.) completely prevented clonidine-induced CWE and attenuated propranolol-induced CWE by 53%. Pretreatment with a beta-adrenergic agonist (isoproterenol, 4 mg kg(-1), i.m.) abolished the effect of clonidine. None of the above treatments was found to elicit significant CWE in nonacclimated (NAc) pigeons. These findings, in addition to previously reported data, indicate a complex regulatory pathway of CWE in the heat-acclimated pigeon consisting of alpha2- and beta2-adrenergic receptors. The possible hierarchical pattern of these receptors is discussed. PMID:15596385

  8. Demonstration of. beta. -adrenergic receptors and catecholamine-mediated effects on cell proliferation in embryonic palatal tissue

    SciTech Connect

    Pisano, M.M.

    1986-01-01

    The ability of catecholamines to modulate cell proliferation, differentiation and morphogenesis in other systems, and modulate adenylate cyclase activity in the developing palate during the period of cellular differentiation, made it of interest to determine their involvement in palatal ontogenesis. Catecholamines exert their physiologic effects via interaction with distinct membrane-bound receptors, one class being the B-adrenergic receptors which are coupled to stimulation of adenylate cyclase and the generation of cAMP. A direct radioligand binding technique utilizing the B-adrenergic antagonist (/sup 3/H)-dihydroalprenolol ((/sup 3/H)-DHA) was employed in the identification of B-adrenergic receptors in the developing murine secondary palate. Specific binding of (/sup 3/H)-DHA in embryonic (day 13) palatal tissue homogenates was saturable and of high affinity. The functionality of B-adrenergic receptor binding sites was assessed from the ability of embryonic palate mesenchmyal cells in vitro to respond to catecholamines with elevations of cAMP. Embryonic palate mesenchymal cells responded to various B-adrenergic catecholamine agonists with significant, dose-dependent accumulations of intracellular cAMP. Embryonic (day 13) maxillary tissue homogenates were analyzed for the presence of catecholamines by high performance liquid chromatography and radioenzymatic assay. Since normal palatal and craniofacial morphogenesis depends on proper temporal and spatial patterns of growth, the effect of B-adrenergic catecholamines on embryonic palate mesenchymal cell proliferation was investigated.

  9. Receptor mechanisms and circuitry underlying NMDA antagonist neurotoxicity.

    PubMed

    Farber, N B; Kim, S H; Dikranian, K; Jiang, X P; Heinkel, C

    2002-01-01

    NMDA glutamate receptor antagonists are used in clinical anesthesia, and are being developed as therapeutic agents for preventing neurodegeneration in stroke, epilepsy, and brain trauma. However, the ability of these agents to produce neurotoxicity in adult rats and psychosis in adult humans compromises their clinical usefulness. In addition, an NMDA receptor hypofunction (NRHypo) state might play a role in neurodegenerative and psychotic disorders, like Alzheimer's disease and schizophrenia. Thus, understanding the mechanism underlying NRHypo-induced neurotoxicity and psychosis could have significant clinically relevant benefits. NRHypo neurotoxicity can be prevented by several classes of agents (e.g. antimuscarinics, non-NMDA glutamate antagonists, and alpha(2) adrenergic agonists) suggesting that the mechanism of neurotoxicity is complex. In the present study a series of experiments was undertaken to more definitively define the receptors and complex neural circuitry underlying NRHypo neurotoxicity. Injection of either the muscarinic antagonist scopolamine or the non-NMDA antagonist NBQX directly into the cortex prevented NRHypo neurotoxicity. Clonidine, an alpha(2) adrenergic agonist, protected against the neurotoxicity when injected into the basal forebrain. The combined injection of muscarinic and non-NMDA Glu agonists reproduced the neurotoxic reaction. Based on these and other results, we conclude that the mechanism is indirect, and involves a complex network disturbance, whereby blockade of NMDA receptors on inhibitory neurons in multiple subcortical brain regions, disinhibits glutamatergic and cholinergic projections to the cerebral cortex. Simultaneous excitotoxic stimulation of muscarinic (m(3)) and glutamate (AMPA/kainate) receptors on cerebrocortical neurons appears to be the proximal mechanism by which the neurotoxic and psychotomimetic effects of NRHypo are mediated. PMID:11803444

  10. Molecular characterization of an. alpha. sub 2B -adrenergic receptor

    SciTech Connect

    Harrison, J.K.; Dewan Zeng; D'Angelo, D.D.; Tucker, A.L.; Zhihong Lu; Barber, C.M.; Lynch, K.R. )

    1990-02-26

    {alpha}{sub 2}-Adrenergic receptors comprise a heterogeneous population based on pharmacologic and molecular evidence. The authors have isolated a cDNA clone (pRNG{alpha}2) encoding a previously undescribed third subtype of an {alpha}{sub 2}-adrenergic receptor from a rat kidney cDNA library. The library was screened with an oligonucleotide encoding a highly conserved region found in all biogenic amine receptors described to date. The deduced amino acid sequence displays many features of G-protein coupled receptors with exception of the absence of the consensus N-linked glycosylation site at the amino terminus. Membranes prepared from COS-1 cells transfected with pRNG{alpha}2 display high affinity and saturable binding to {sup 3}H-rauwolscine (K{sub d}=2 nM).Competition curve data analysis shows that pRNG{alpha}2 protein binds to a variety of adrenergic drugs with the following rank order of potency: yohimbine {ge} cholorpromazine > prazosin {ge} clonidine > norepinephrine {ge} oxymetazoline. pRNG{alpha}2 RNA accumulates in both adult rat kidney and rat neonatal lung (predominant species is 4.0 kb). They conclude that pRNG{alpha}2 likely represents a cDNA for the {alpha}{sub 2B}-adrenergic receptor.

  11. The emerging pharmacogenomics of the beta-adrenergic receptors.

    PubMed

    Taylor, Matthew R G; Bristow, Michael R

    2004-01-01

    Beta-adrenergic signaling mechanisms are of central importance to cardiovascular health and disease. Modulation of these pathways represents an important pharmacologic approach to the treatment of heart failure and hypertension. Advances in molecular genetics have identified genetic polymorphisms in the human beta-adrenergic receptor genes; some of this variation predicts changes in protein sequence/structure, and potentially changes in function, of the b-adrenergic receptors. This article reviews the current state of knowledge and understanding of the genetic variation present in the three human beta-adrenergic receptor genes. Already, variation in these genes has been associated with observed differences in several cardiovascular phenotypes. This work has led to the demonstration of functional differences in activity between receptors with certain known polymorphisms and "wild-type" receptors. An understanding of these polymorphisms is key to the development of studies of how differences in drug response/effects may be mediated by these polymorphisms. Such studies are anticipated to provide a foundation for the development of novel pharmacologic approaches where selection of and dosing of cardiovascular therapy is tailored to individuals on the basis of each patient's specific genetic makeup. PMID:15591842

  12. Adrenergic receptors on cerebral microvessels in control and Parkinsonian subjects

    SciTech Connect

    Cash, R.; Lasbennes, F.; Sercombe, R.; Seylaz, J.; Agid, Y.

    1985-08-12

    The binding of adrenergic ligands (/sup 3/H-prazosin, /sup 3/H-clonidine, /sup 3/H-dihydroalprenolol) was studied on a preparation of cerebral microvessels in the prefrontal cortex and putamen of control and Parkinsonian subjects. The adrenergic receptor density in microvessels of control patients was less than 0.5% and 3.3% respectively of the total binding. A significant decrease in the number of alpha-1 binding sites was observed on microvessels in the putamen of patients with Parkinson's disease. 22 references, 2 tables.

  13. Alpha-2 adrenergic receptor-mediated inhibition of thermogenesis

    PubMed Central

    Madden, Christopher J.; Tupone, Domenico; Cano, Georgina; Morrison, Shaun F.

    2013-01-01

    Alpha2-adrenergic receptor (α2-AR) agonists have been use as anti-hypertensive agents, in the management of drug withdrawal, and as sedative analgesics. Since α2-AR agonists also influence the regulation of body temperature, we explored their potential as antipyretic agents. This study delineates the central neural substrate for the inhibition of rat brown adipose tissue (BAT) and shivering thermogenesis by α2-AR agonists. Nanoinjection of the α2-AR agonist, clonidine (1.2 nmol), into the rostral raphe pallidus (rRPa) inhibited BAT sympathetic nerve activity (SNA) and BAT thermogenesis. Subsequent nanoinjection of the α2-AR antagonist, idazoxan (6nmol) into the rRPa reversed the clonidine-evoked inhibition of BAT SNA and BAT thermogenesis. Systemic administration of the α2-AR agonists, dexmedetomidine (25ug/kg, iv) or clonidine (100ug/kg, iv) inhibited shivering EMGs, BAT SNA and BAT thermogenesis effects that were reversed by nanoinjection of idazoxan (6nmol) into the rRPa. Dexmedetomidine (100µg/kg, ip) prevented and reversed lipopolysaccharide (10µg/kg ip)-evoked thermogenesis in free-behaving rats. Cholera toxin subunit b retrograde tracing from rRPa and pseudorabies virus transynaptic retrograde tracing from BAT combined with immunohistochemistry for catecholaminergic biosynthetic enzymes revealed the ventrolateral medulla as the source of catecholaminergic input to the rRPa and demonstrated that these catecholaminergic neurons are synaptically connected to BAT. Photostimulation of VLM neurons expressing of the PRSx8-ChR2-mCherry lentiviral vector inhibited BAT SNA via activation of α2-ARs in the rRPa. These results indicate a potent inhibition of BAT and shivering thermogenesis by α2-AR activation in the rRPa, and suggest a therapeutic potential of α2-AR agonists for reducing potentially-lethal elevations in body temperature during excessive fever. PMID:23365239

  14. Propranolol, a beta-adrenergic antagonist, retards response to MSH in skin of Anolis carolinensis.

    PubMed

    Vaughan, G L; Greenberg, N

    1987-01-01

    Lacking sympathetic innervation, the skin of A. carolinensis, an iguanid lizard, darkens within minutes in response to circulating melanocyte stimulating hormone (MSH) or beta adrenergic agonists such as epinephrine (EPI). This change is produced by dispersion of melanin from a perinculear position within dermal melanophores into superficial dendritic processes. These melanophores possess alpha-2 and beta-2 adrenergic as well as MSH receptors except in a patch of skin behind the eye, the eyespot, which lacks alpha receptors. Activation of beta or MSH receptors leads to stimulation of adenyl cyclase whereas alpha stimulation inhibits the enzyme to override the others. In a series of trials, injection of saline or propranolol was followed after 30 minutes by saline, EPI, or MSH. Propranolol inhibited chromatophore response to EPI. It also, unexpectedly, retarded the response to MSH, increasing latency to eyespot formation and body color change as well as the duration of darkening for both. Alteration of MSH response by a beta blocker could be explained by linkage of both adrenergic receptors and the MSH receptor to a common adenyl cyclase molecule to form a functional unit in the membrane of the melanophore. PMID:3671516

  15. Stimulation of α2-adrenergic receptors in the central nucleus of the amygdala attenuates stress-induced reinstatement of nicotine seeking in rats

    PubMed Central

    Yamada, Hidetaka; Bruijnzeel, Adrie W.

    2010-01-01

    Tobacco addiction is a chronic disorder that is characterized by craving for tobacco products, withdrawal upon smoking cessation, and relapse after periods of abstinence. Previous studies demonstrated that systemic administration of α2-adrenergic receptor agonists attenuates stress-induced reinstatement of drug seeking in rats. The aim of the present experiments was to investigate the role of noradrenergic transmission in the central nucleus of amygdala (CeA) in stress-induced reinstatement of nicotine seeking. Rats self-administered nicotine for 14–16 days and then nicotine seeking was extinguished by substituting saline for nicotine. The effect of the intra-CeA infusion of the α2-adrenergic receptor agonists clonidine and dexmedetomidine, the nonselective β1/β2-adrenergic receptor antagonist propranolol, and the α1-adrenergic receptor antagonist prazosin on stress-induced reinstatement of nicotine seeking was investigated. In all the experiments, exposure to footshocks reinstated extinguished nicotine seeking. The administration of clonidine or dexmedetomidine into the CeA attenuated stress-induced reinstatement of nicotine seeking. The administration of propranolol or prazosin into the CeA did not affect stress-induced reinstatement of nicotine seeking. Furthermore, intra-CeA administration of clonidine or dexmedetomidine did not affect operant responding for food pellets. This suggests that the effects of clonidine and dexmedetomidine on stress-induced reinstatement of nicotine seeking were not mediated by motor impairments or sedation. Taken together, these findings indicate that stimulation of α2-adrenergic receptors, but not blockade of α1 or β-adrenergic receptors, in the CeA attenuates stress-induced reinstatement of nicotine seeking. These findings suggest that α2-adrenergic receptor agonists may at least partly attenuate stress-induced reinstatement of nicotine seeking by stimulating α2-adrenergic receptors in the CeA. PMID:20854830

  16. Relationship between alpha 1-adrenergic receptor occupancy and response in BC3H-1 muscle cells

    SciTech Connect

    Brown, R.D.; Berger, K.D.; Taylor, P.

    1987-07-01

    The relationship between alpha 1-adrenergic receptor occupancy by agonists or antagonists and the regulation of intracellular Ca/sup 2 +/ was examined. Receptor occupancy was measured using the antagonist (/sup 3/H)prazosin and correlated with agonist-elicited /sup 45/Ca/sup 2 +/ fluxes. The agonists epinephrine (E), norepinephrine (NE), and phenylephrine (PE) coordinately activated Ca/sup 2 +/ efflux, reflecting a substantial mobilization of intracellular Ca/sup 2 +/, as well as a smaller /sup 45/Ca/sup 2 +/ influx. The agonist concentration dependences for influx and efflux were similar, with the order of potency expected for alpha 1 receptors (E greater than or equal to NE greater than PE). To determine the relationship between receptor occupancy and response, the slowly dissociating antagonist prazosin was used to inactivate specified fractions of the receptor population. A linear relationship was observed between the remaining activatable receptors and residual /sup 45/Ca/sup 2 +/ efflux elicited by E or NE, except at saturating agonist concentrations where some curvature was observed. Moreover, the concentration dependence for agonist-elicited /sup 45/Ca/sup 2 +/ efflux was shifted toward slightly higher concentrations of E or NE following prazosin inactivation. These results suggest the presence of a modest receptor reserve which is revealed by E or NE, but not by PE. Agonist occupation was measured over the same interval as receptor activation by competition with the initial rate of (/sup 3/H)prazosin association. All three agonists exhibited the major fraction of receptor occupation over the same concentration ranges required for the functional response. Exposure of receptors to specified agonist concentrations for 30 min had little effect on the number of receptors or their ligand affinities, whereas a 2.5-hr exposure to agonist decreased apparent agonist affinity as well as the number of receptors recognized by (/sup 3/H)prazosin.

  17. Characterization and distribution of alpha 2-adrenergic receptors in the human intestinal mucosa.

    PubMed Central

    Valet, P; Senard, J M; Devedjian, J C; Planat, V; Salomon, R; Voisin, T; Drean, G; Couvineau, A; Daviaud, D; Denis, C

    1993-01-01

    The subtype and the expression of the alpha 2-adrenergic receptor were investigated in the normal mucosa from human intestine by means of radioligand binding, RNase mapping, and measurement of adenylate cyclase activity. The study of the binding of the alpha 2-adrenergic antagonist, [3H]RX821002, to epithelial cell membranes indicated the existence of a single class of noninteracting sites displaying a high affinity for the radioligand (Kd = 1.1 +/- 0.5 nM). The rank order of potency of antagonists to inhibit [3H]RX821002 binding (RX821002 > yohimbine = rauwolscine > phentolamine approximately idazoxan >> chlorpromazine > prazosin) suggested that the receptor is of the alpha 2A subtype. A conclusion which is confirmed by the fact that only alpha 2C10 transcripts were found in the human intestine mucosa. Competition curves with (-)-norepinephrine demonstrated that 60% of the receptor population exhibited high affinity for agonists. This high-affinity state was abolished by the addition of GTP plus Na+ or by prior treatment of the membranes with pertussis toxin indicating it corresponded to G protein-coupled receptors. [32P]ADP-ribosylation and immunoblotting experiments identified two pertussis toxin-sensitive G proteins corresponding to Gi2 and Gi3. The study of the distribution of the receptor indicated that (a) the proximal colon is the intestine segment exhibiting the highest receptor density and (b) the receptor is predominantly expressed in crypts and is preferentially located in the basolateral membrane of the polarized cell. The distribution of the receptor along the crypt-surface axis of the colon mucosa can be correlated with a higher level of alpha 2C10-specific mRNA and a higher efficiency of UK14304 to inhibit adenylate cyclase in crypt cells. Images PMID:8098045

  18. Tetrahydroquinoline derivatives as opioid receptor antagonists.

    PubMed

    Zhang, Cunyu; Westaway, Susan M; Speake, Jason D; Bishop, Michael J; Goetz, Aaron S; Carballo, Luz Helena; Hu, Mike; Epperly, Andrea H

    2011-01-15

    Opioid receptors play an important role in both behavioral and homeostatic functions. We herein report tetrahydroquinoline derivatives as opioid receptor antagonists. SAR studies led to the identification of the potent antagonist 2v, endowed with 1.58nM (K(i)) functional activity against the μ opioid receptor. DMPK data suggest that novel tetrahydroquinoline analogs may be advantageous in peripheral applications. PMID:21193310

  19. Maternal defense is modulated by beta adrenergic receptors in lateral septum in mice.

    PubMed

    Scotti, Melissa-Ann L; Lee, Grace; Gammie, Stephen C

    2011-06-01

    Maternal defense (offspring protection) is a critical and highly conserved component of maternal care in mammalian systems that involves dramatic shifts in a female's behavioral response to social cues. Numerous changes occur in neuronal signaling and connectivity in the postpartum female, including decreases in norepinephrine (NE) signaling in subregions of the CNS. In this study using a strain of mice selected for maternal defense, we examined whether possible changes in NE signaling in the lateral septum (LS) could facilitate expression of maternal aggression. In separate studies that utilized a repeated measures design, mice were tested for maternal defense following intra-LS injections of either the β-adrenergic receptor agonist isoproterenol (10 μg or 30 μg) or vehicle (Experiment 1), the β-adrenergic receptor antagonist propranolol (2 μg) or vehicle (Experiment 2), or the β1-receptor antagonist, atenolol (Experiment 3). Mice were also evaluated for light-dark performance and pup retrieval. Thirty micrograms of the agonist isoproterenol significantly decreased number of attacks and time aggressive relative to vehicle without affecting pup retrieval or light-dark box performance. In contrast, the antagonist propranolol significantly increased maternal aggression (lowered latency to attack and increased total attack time) without altering light-dark box test. The β1-specific antagonist, atenolol, significantly decreased latency to attack (1 μg vs. vehicle) without altering other measures. Although the findings were identified in a unique strain of mice, the results of these studies support the hypothesis that changes in NE signaling in LS during the postpartum period contribute to the expression of offspring protection. PMID:21480688

  20. Inhibition of opioid release in the rat spinal cord by α2C adrenergic receptors

    PubMed Central

    Chen, Wenling; Song, Bingbing; Marvizón, Juan Carlos G.

    2008-01-01

    Neurotransmitter receptors that control the release of opioid peptides in the spinal cord may play an important role in pain modulation. Norepinephrine, released by a descending pathway originating in the brainstem, is a powerful inducer of analgesia in the spinal cord. Adrenergic α2C receptors are present in opioid-containing terminals in the dorsal horn, where they could modulate opioid release. The goal of this study was to investigate this possibility. Opioid release was evoked from rat spinal cord slices by incubating them with the sodium channel opener veratridine in the presence of peptidase inhibitors (actinonin, captopril and thiorphan), and was measured in situ through the internalization of μ-opioid receptors in dorsal horn neurons. Veratridine produced internalization in 70% of these neurons. The α2 receptor agonists clonidine, guanfacine, medetomidine and UK-14304 inhibited the evoked μ-opioid receptor internalization with IC50s of 1.7 μM, 248 nM, 0.3 nM and 22 nM, respectively. However, inhibition by medetomidine was only partial, and inhibition by UK-14304 reversed itself at concentrations higher than 50 nM. None of these agonists inhibited μ-opioid receptor internalization produced by endomorphin-2, showing that they inhibited opioid release and not the internalization itself. The inhibition produced by clonidine, guanfacine or UK-14304 was completely reversed by the selective α2C antagonist JP-1203. In contrast, inhibition by guanfacine was not prevented by the α2A antagonist BRL-44408. These results show that α2C receptors inhibit the release of opioids in the dorsal horn. This action may serve to shut down the opioid system when the adrenergic system is active. PMID:18343461

  1. The Alpha-1A Adrenergic Receptor in the Rabbit Heart

    PubMed Central

    Myagmar, Bat-Erdene; Swigart, Philip M.; Baker, Anthony J.; Simpson, Paul C.

    2016-01-01

    The alpha-1A-adrenergic receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with <1% alpha-1A and alpha-1D, whereas alpha-1A mRNA was over 50% of total in brain and liver. Saturation radioligand binding identified ~4 fmol total alpha-1-ARs per mg myocardial protein, with 17% alpha-1A by competition with the selective antagonist 5-methylurapidil. The alpha-1D was not detected by competition with BMY-7378, indicating that 83% of alpha-1-ARs were alpha-1B. In isolated left ventricle and right ventricle, the selective alpha-1A agonist A61603 stimulated a negative inotropic effect, versus a positive inotropic effect with the nonselective alpha-1-agonist phenylephrine and the beta-agonist isoproterenol. Blood pressure assay in conscious rabbits using an indwelling aortic telemeter showed that A61603 by bolus intravenous dosing increased mean arterial pressure by 20 mm Hg at 0.14 μg/kg, 10-fold lower than norepinephrine, and chronic A61603 infusion by iPRECIO programmable micro Infusion pump did not increase BP at 22 μg/kg/d. A myocardial slice model useful in human myocardium and an anthracycline cardiotoxicity model useful in mouse were both problematic in rabbit. We conclude that alpha-1A mRNA is very low in rabbit heart, but the receptor is present by binding and mediates a negative inotropic response. Expression and function of the alpha-1A in rabbit heart differ from mouse and human, but the vasopressor response is similar to mouse. PMID:27258143

  2. The Alpha-1A Adrenergic Receptor in the Rabbit Heart.

    PubMed

    Thomas, R Croft; Cowley, Patrick M; Singh, Abhishek; Myagmar, Bat-Erdene; Swigart, Philip M; Baker, Anthony J; Simpson, Paul C

    2016-01-01

    The alpha-1A-adrenergic receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with <1% alpha-1A and alpha-1D, whereas alpha-1A mRNA was over 50% of total in brain and liver. Saturation radioligand binding identified ~4 fmol total alpha-1-ARs per mg myocardial protein, with 17% alpha-1A by competition with the selective antagonist 5-methylurapidil. The alpha-1D was not detected by competition with BMY-7378, indicating that 83% of alpha-1-ARs were alpha-1B. In isolated left ventricle and right ventricle, the selective alpha-1A agonist A61603 stimulated a negative inotropic effect, versus a positive inotropic effect with the nonselective alpha-1-agonist phenylephrine and the beta-agonist isoproterenol. Blood pressure assay in conscious rabbits using an indwelling aortic telemeter showed that A61603 by bolus intravenous dosing increased mean arterial pressure by 20 mm Hg at 0.14 μg/kg, 10-fold lower than norepinephrine, and chronic A61603 infusion by iPRECIO programmable micro Infusion pump did not increase BP at 22 μg/kg/d. A myocardial slice model useful in human myocardium and an anthracycline cardiotoxicity model useful in mouse were both problematic in rabbit. We conclude that alpha-1A mRNA is very low in rabbit heart, but the receptor is present by binding and mediates a negative inotropic response. Expression and function of the alpha-1A in rabbit heart differ from mouse and human, but the vasopressor response is similar to mouse. PMID:27258143

  3. Role of. alpha. sub 2 -adrenergic receptors in the carotid body response to hypoxia

    SciTech Connect

    Kou, Y.R.; Ernsberger, P.; Cherniack, N.S.; Prabhakar, N.R. )

    1990-02-26

    Clonidine, which acts in part as an {alpha}{sub 2}-adrenergic receptor agonist, depresses ventilation. The authors examined the role of {alpha}{sub 2}-receptors in carotid chemoreceptor activity. The density of {alpha}{sub 2}-receptors was determined in membrane fractions of 18 cat carotid bodies using {sup 125}I-iodoclonidine with 0.1 mM epinephrine or 10 {mu}M SKF-86466 defining nonspecific binding. {alpha}{sub 2}-Adrenergic receptor density averaged 0.6{plus minus}0.1 fmol/carotid body (mean {plus minus} SEM) and was comparable to other sympathetic target tissues. The authors then studied the effects of an agonist (guanabenz) and an antagonist (SKF-86466; 6-Cl-N-methyl-2,3,4,5-tetrahydro-1-H3-benzazepine) specific for {alpha}{sub 2}-receptors on baseline and hypoxia-stimulated carotid body discharge, in 10 anesthetized, paralyzed and artificially ventilated cats. Intracarotid infusion of guanabenz for 5 minutes caused a dose-dependent depression of the baseline activity and reduced the chemoreceptor response to hypoxia by 88.0{plus minus}5.8% of the vehicle-injected controls. Intravenous administration of SKF-86466 reversed the effects of guanabenz on the carotid body activity. in contrast, chemoreceptor depression caused by dopamine was unaffected by SKF-86466. SKF-86466 alone increased baseline discharge and potentiated the chemoreceptor response to hypoxia by 34.0 {plus minus} 9.6% of the controls. These results demonstrate that {alpha}{sub 2}-adrenergic receptors are present in the cat carotid body and they exert an inhibitory influence on the chemoreceptor response to hypoxia.

  4. Cardiac and neuroprotection regulated by α1-adrenergic receptor subtypes

    PubMed Central

    Perez, Dianne M.; Doze, Van A.

    2013-01-01

    Sympathetic nervous system regulation by the α1-adrenergic receptor (AR) subtypes (α1A, α1B, α1D) is complex, whereby chronic activity can be either detrimental or protective for both heart and brain function. This review will summarize the evidence that this dual regulation can be mediated through the different α1-AR subtypes in the context of cardiac hypertrophy, heart failure, apoptosis, ischemic preconditioning, neurogenesis, locomotion, neurodegeneration, cognition, neuroplasticity, depression, anxiety, epilepsy, and mental illness. PMID:21338248

  5. Postcountershock myocardial damage after pretreatment with adrenergic and calcium channel antagonists in halothane-anesthetized dogs

    SciTech Connect

    Gaba, D.M.; Metz, S.; Maze, M.

    1985-05-01

    Transthoracic electric countershock can cause necrotic myocardial lesions in humans as well as experimental animals. The authors investigated the effect on postcountershock myocardial damage of pretreatment with prazosin, an alpha-1 antagonist; L-metoprolol, a beta-1 antagonist, and verapamil, a calcium channel-blocking agent. Twenty dogs were anesthetized with halothane and given two transthoracic countershocks of 295 delivered joules each after drug or vehicle treatment. Myocardial injury was quantitated 24 h following countershock by measuring the uptake of technetium-99m pyrophosphate in the myocardium. Elevated technetium-99m pyrophosphate uptake occurred in visible lesions in most dogs regardless of drug treatment. For each of four parameters of myocardial damage there was no statistically significant difference between control animals and those treated with prazosin, metoprolol, or verapamil. These data suggest that adrenergic or calcium channel-mediated mechanisms are not involved in the pathogenesis of postcountershock myocardial damage.

  6. Alpha-1-Adrenergic Receptors: Targets for Agonist Drugs to Treat Heart Failure

    PubMed Central

    Jensen, Brian C.; O'Connell, Timothy D.; Simpson, Paul C.

    2011-01-01

    Evidence from cell, animal, and human studies demonstrates that α1-adrenergic receptors mediate adaptive and protective effects in the heart. These effects may be particularly important in chronic heart failure, when catecholamine levels are elevated and β-adrenergic receptors are down regulated and dysfunctional. This review summarizes these data and proposes that selectively activating α1-adrenergic receptors in the heart may represent a novel and effective way to treat heart failure. PMID:21118696

  7. Murine Hematopoietic Stem cells and Progenitors Express Adrenergic Receptors

    PubMed Central

    Muthu, Kuzhali; Iyer, Sivaraman; He, L-K.; Szilagyi, Andrea; Gamelli, Richard L; Shankar, Ravi; Jones, Stephen B

    2007-01-01

    Association between the nervous and immune system is well documented. Immune cells originate within the bone marrow that is innervated. Thermal injury induces adrenergic stimulation, augments monocytopoiesis and alters the β-adrenergic receptor (AR) profile of bone marrow monocyte committed progenitors. This provides an impetus to study AR expression in hematopoietic progenitors along myeloid lineage. Using FACS analysis and confocal microscopy, we report the expression of α1-, α2- and β2- AR in enriched populations of ER-MP20+ and ER-MP12+ myeloid progenitors, CD117+ and CD34+ multi-potential progenitors and more importantly pluripotent stem cells suggesting a plausible role for catecholamine in hematopoietic development. PMID:17428548

  8. Effect of alpha1-adrenergic receptors in cardiac pathophysiology.

    PubMed

    Shannon, Richard; Chaudhry, Mohammad

    2006-11-01

    Compelling evidence now exists that proves adrenergic blockade is at the center of neurohormonal antagonism in heart failure (HF). Catecholamines are well known to act through both beta- and alpha-adrenergic receptors (ARs), which mediate their effects through distinct receptor pathways. Beta-AR blockers are commonly used in the treatment of HF and have distinct receptor affinity profiles. The recent COMET trial comparing 2 important beta-blocking drugs showed a distinct advantage for carvedilol in decreasing the risk of mortality from HF. The mechanism of action for carvedilol differs from metoprolol tartrate in its ability to block both alpha- and beta-ARs, leading to renewed interest in the potential role of alpha-ARs in the progression of HF. In contrast, however, the ALLHAT study discontinued use of doxazosin, an alpha1-receptor blocker because of an increase in cardiovascular events among patients using this drug. The results of these studies appear to be in contrast with respect to the role of alpha-ARs in regards to cardiovascular pathophysiology. Further study of the alpha-receptor and understanding the role of alpha-ARs in HF is necessary to understand the therapeutic effect of alpha-blockade. This article reviews our understanding of the alpha-AR in HF. PMID:17070143

  9. β-Adrenergic agonists mediate enhancement of β1-adrenergic receptor N-terminal cleavage and stabilization in vivo and in vitro.

    PubMed

    Hakalahti, Anna E; Khan, Hamayun; Vierimaa, Miia M; Pekkala, Emilia H; Lackman, Jarkko J; Ulvila, Johanna; Kerkelä, Risto; Petäjä-Repo, Ulla E

    2013-01-01

    The β(1)-adrenergic receptor (β(1)AR) is the predominant βAR in the heart and is the main target for β-adrenergic antagonists, widely used in the treatment of cardiovascular diseases. Previously, we have shown that the human (h) β(1)AR is cleaved in its N terminus by a metalloproteinase, both constitutively and in a receptor activation-dependent manner. In this study, we investigated the specific events involved in β(1)AR regulation, focusing on the effects of long-term treatment with β-adrenergic ligands on receptor processing in stably transfected human embryonic kidney 293(i) cells. The key findings were verified using the transiently transfected hβ(1)AR and the endogenously expressed receptor in neonatal rat cardiomyocytes. By using flow cytometry and Western blotting, we demonstrated that isoproterenol, S-propranolol, CGP-12177 [4-[3-[(1,1-dimethylethyl)amino]2-hydroxypropoxy]-1,3-dihydro-2H-benzimidazol-2-one], pindolol, and timolol, which displayed agonistic properties toward the β(1)AR in either the adenylyl cyclase or the mitogen-activated protein kinase signaling pathways, induced cleavage of the mature cell-surface receptor. In contrast, metoprolol, bisoprolol, and CGP-20712 [1-[2-((3-carbamoyl-4-hydroxy)phenoxy)ethylamino]-3-[4-(1-methyl-4-trifluoromethyl-2-imidazolyl)phenoxy]-2-propanol], which showed no agonistic activity, had only a marginal or no effect. Importantly, the agonists also stabilized intracellular receptor precursors, possibly via their pharmacological chaperone action, and they stabilized the receptor in vitro. The opposing effects on the two receptor forms thus led to an increase in the amount of cleaved receptor fragments at the plasma membrane. The results underscore the pluridimensionality of β-adrenergic ligands and extend this property from receptor activation and signaling to the regulation of β(1)AR levels. This phenomenon may contribute to the exceptional resistance of β(1)ARs to downregulation and tendency toward

  10. Regulation of subtypes of beta-adrenergic receptors in rat brain following treatment with 6-hydroxydopamine

    SciTech Connect

    Johnson, E.W.; Wolfe, B.B.; Molinoff, P.B.

    1989-07-01

    The technique of quantitative autoradiography has been used to localize changes in the densities of subtypes of beta-adrenergic receptors in rat brain following treatment with 6-hydroxydopamine. Previously reported increases in the density of beta 1-adrenergic receptors in the cerebral cortex were confirmed. The anatomical resolution of autoradiography made it possible to detect changes in the density of beta 2-adrenergic receptors in the cortex and in a number of other brain regions. The density of beta 1-adrenergic receptors increased from 30 to 50% depending on the region of the cortex being examined. The increase in the somatomotor cortex was greater than that in the frontal or occipital cortex. The increase in the density of beta 2-adrenergic receptors in the cortex was not as widespread as that of beta 1-adrenergic receptors and occurred primarily in frontal cortex, where the density of receptors increased by 40%. The densities of both beta 1- and beta 2-adrenergic receptors increased in a number of forebrain, thalamic, and midbrain structures. Selective changes in the density of beta 1-adrenergic receptors were observed in the superficial gray layer of the superior colliculus and in the amygdala. The density of beta 2-adrenergic receptors increased in the caudate-putamen, the substantia nigra, and the lateral and central nuclei of the thalamus, whereas the density of beta 1-adrenergic receptors did not change in these regions. The densities of both subtypes of beta-adrenergic receptors increased in the hippocampus, the cerebellum, the lateral posterior nucleus of the thalamus, and the dorsal lateral geniculate.

  11. Characteristics of myocardial US -adrenergic receptors during endotoxicosis in the rat

    SciTech Connect

    Romano, F.D.; Jones, S.B.

    1986-08-01

    The effects of in vivo endotoxin administration on US -adrenergic receptors in rat ventricle membranes were studied using (TH)dihydroalprenolol as a radioligand. Nonlinear regression analysis of saturation binding indicated one-site binding of antagonist in both control and endotoxic tissues. There was no change in maximum binding or dissociation constant of (TH)dihydroalprenolol at 0.5 or 3 h after endotoxin administration or when the rats were in the agonal stage of shock. Isoproterenol competition studies revealed that there was an increase in the slope of the curve from endotoxic tissues at the agonal stages and that there was a decrease in affinity for isoproterenol binding. Control binding modeled to a two-state fit, whereas binding to endotoxin-exposed membranes modeled to one state of lower affinity. These data suggest that there is an alteration in receptor-adenylate cyclase coupling, which may account for an attenuation of agonist-stimulated cyclase activity. A modification in the US -adrenergic receptor may contribute to the decrease in myocardial performance during shock.

  12. Characterisation of AmphiAmR4, an amphioxus (Branchiostoma floridae) α₂-adrenergic-like G-protein-coupled receptor.

    PubMed

    Bayliss, Asha; Evans, Peter D

    2013-06-01

    Little is known about the evolutionary relationship between vertebrate adrenergic receptors and invertebrate octopamine and tyramine receptors. The complexity of the adrenergic signalling system is believed to be an innovation of the vertebrate lineage but the presence of noradrenaline has been reported in some invertebrate species. The cephalochordate, amphioxus (Branchiostoma floridae), is an ideal model organism for studying the evolution of vertebrate GPCRs, given its unique position at the base of the chordate lineage. Here, we describe the pharmacological characterisation and second messenger coupling abilities of AmphiAmR4, which clusters with α₂-adrenergic receptors in a phylogenetic tree but also shares a high sequence similarity to invertebrate octopamine/tyramine receptors in both BLAST and Hidden Markov Model analyses. Thus, it was of particular interest to determine if AmphiAmR4 displayed similar functional properties to the vertebrate α₂-adrenergic receptors or to invertebrate octopamine or tyramine receptors. When stably expressed in Chinese hamster ovary (CHO) cells, noradrenaline couples the receptor to both the activation of adenylyl cyclase and to the activation of the MAPKinase pathway. Pharmacological studies with a wide range of agonists and antagonists suggest that AmphiAmR4 functions as an α₂-adrenergic-like receptor when expressed in CHO cells. PMID:23183848

  13. Endothelin receptor antagonists in pulmonary arterial hypertension.

    PubMed

    Channick, Richard N; Sitbon, Olivier; Barst, Robyn J; Manes, Alessandra; Rubin, Lewis J

    2004-06-16

    Endothelin receptor antagonism has emerged as an important therapeutic strategy in pulmonary arterial hypertension (PAH). Laboratory and clinical investigations have clearly shown that endothelin (ET)-1 is overexpressed in several forms of pulmonary vascular disease and likely plays a significant pathogenetic role in the development and progression of pulmonary vasculopathy. Oral endothelin receptor antagonists (ERAs) have been shown to improve pulmonary hemodynamics, exercise capacity, functional status, and clinical outcome in several randomized placebo-controlled trials. Bosentan, a dual-receptor antagonist, is approved by the U.S. Food and Drug Administration for class III and IV patients with PAH, based on two phase III trials. In addition to its efficacy as sole therapy, bosentan may have a role as part of a combination of drugs such as a prostanoid or sildenafil. The selective endothelin receptor-A antagonists sitaxsentan and ambrisentan are currently undergoing investigation. PMID:15194180

  14. Histamine-2 Receptor Antagonists and Semen Quality.

    PubMed

    Banihani, Saleem A

    2016-01-01

    Histamine-2 receptor antagonists are a class of drugs used to treat the acid-related gastrointestinal diseases such as ulcer and gastro-oesophageal reflux disease. Although such drugs, especially ranitidine and famotidine, are still widely used, their effects on semen quality, and hence on male infertility, is still unclear. This MiniReview systematically addresses and summarizes the effect of histamine-2 receptor antagonists (cimetidine, ranitidine, nizatidine and famotidine) on semen quality, particularly, on sperm function. Cimetidine appears to have adverse effects on semen quality. While the effects of ranitidine and nizatidine on semen quality are still controversial, famotidine does not appear to change semen quality. Therefore, additional studies will be required to clarify whether histamine-2 receptor-independent effects of these drugs play a role in semen quality as well as further clinical studies including direct comparison of the histamine-2 receptor antagonists. PMID:26176290

  15. Solubilization and purification of the alpha 1-adrenergic receptor using a novel affinity resin.

    PubMed Central

    Graham, R M; Hess, H J; Homcy, C J

    1982-01-01

    The highly selective alpha 1-adrenergic receptor antagonist prazosin was used to identify binding sites having alpha-adrenergic specificity in rat hepatic plasma membranes. Solubilization of the membrane-bound receptors was achieved by incubation with the nonionic detergent digitonin, and binding activity was assayed by using [3H]prazosin and a polyethylene glycol precipitation technique. Only 20-30% of the total receptor pool was released by the solubilization procedure. However, binding of [3H]prazosin was saturable [maximal value, 206 +/- 8 fmol/mg of protein (membrane) vs. 74 +/- 4 fmol/mg of protein (soluble)] and of high affinity [Kd, 0.6 +/- 0.2 nM (membrane) vs. 0.8 +/- 0.2 nM (soluble)]. To aid in purification of the receptors, an affinity resin was developed using an analog of prazosin, 2-(4-succinoylpiperazin-1-yl)-4-amino-6,7-dimethoxyquinazoline (CP 57,609; Kd 2.7 X 10(-7) M) immobilized via an amide linkage to agarose. The resulting resin demonstrated high affinity (Kd 3.2 X 10(-7) M) for the solubilized receptors, as determined by competitive inhibition assay. The degree of substitution to the resin was determined by a direct radioimmunoassay using antibodies against albumin-complexed CP 57,609 and found to be 0.1 to 0.2 mumol/ml of agarose. Affinity chromatography using the resin resulted in 513-fold purification in a single step. Moreover, the specificity of the purified binding sites was similar to that of membrane-bound receptors. This novel affinity resin should thus provide a powerful tool for isolating the receptor protein in quantities sufficient for detailed biochemical characterization. PMID:6285370

  16. Synthesis and biological evaluation of fluorine-18 labeled RS-15385-197 analogs: Potent and selective alpha-2 adrenergic receptor radioligands for PET

    SciTech Connect

    Enas, J.D.; VanBrocklin, H.F.; Budinger, T.F.; Clark, R.D.

    1997-12-31

    Aberrations in the {alpha}{sub 2}-adrenergic receptor system have been implicated in a number of disease states including hypertension, drug abuse, depression, and neurodegenerative disorders such as Alzheimer`s Disease. RS-15385-FP (1) and RS-15385-FPh (2) are analogs of the {alpha}{sub 2}-adrenergic receptor antagonist RS- 15385-197 which display a high receptor binding affinity (K{sub i} = 0.2 and 0.5 nM, respectively) as well as a high degree of {alpha}{sub 2}/{alpha}{sub 1} selectivity (7000:1 and 2000:1, respectively). We synthesized [F-18]-2 was synthesized by fluoro-for-nitro exchange on the corresponding nitrophenyl derivative which was produced in two steps from the hydroxypropyl sulfonamide. In vivo distribution studies in rats and PET studies in monkeys demonstrate uptake in {alpha}{sub 2}-adrenergic receptor rich regions of the brain, particularly the locus coeruleus.

  17. Adrenergic activation of electrogenic K+ secretion in guinea pig distal colonic epithelium: involvement of beta1- and beta2-adrenergic receptors.

    PubMed

    Zhang, Jin; Halm, Susan T; Halm, Dan R

    2009-08-01

    Adrenergic stimulation of electrogenic K+ secretion in isolated mucosa from guinea pig distal colon required activation of two beta-adrenergic receptor subtypes (beta-AdrR). Addition of epinephrine (epi) or norepinephrine (norepi) to the bathing solution of mucosae in Ussing chambers increased short-circuit current (Isc) and transepithelial conductance (Gt), consistent with this cation secretion. A beta-adrenergic classification was supported by propranolol antagonism of this secretory response and the lack of effect by the alpha-AdrR antagonists BE2254 (alpha1-AdrR) and yohimbine (alpha2-AdrR). Subtype-selective antagonists CGP20712A (beta1-AdrR), ICI-118551 (beta2-AdrR), and SR59320A (beta3-AdrR) were relatively ineffective at inhibiting the epi-stimulated Isc response. In combination, CGP20712A and ICI-118551 inhibited the response, which supported a synergistic action by beta1-AdrR and beta2-AdrR. Expression of mRNA for both beta1-AdrR and beta2-AdrR was indicated by RT-PCR of RNA from colonic epithelial cells. Protein expression was indicated by immunoblot showing bands at molecular weights consistent with monomers and oligomers. Immunoreactivity (ir) for beta1-AdrR and beta2-AdrR was prominent in basolateral membranes of columnar epithelial cells in the crypts of Lieberkühn as well as intercrypt surface epithelium. Cells in the pericryptal sheath also had beta1-AdrR(ir) but did not have discernable beta2-AdrR(ir). The adrenergic sensitivity of K+ secretion measured by Isc and Gt was relatively low as indicated by EC(50)s of 41 +/- 7 nM for epi and 50 +/- 14 nM for norepi. Adrenergic activation of electrogenic K+ secretion required the involvement of both beta1-AdrR and beta2-AdrR, occurring with an agonist sensitivity reduced compared with reported values for either receptor subtype. PMID:19460844

  18. Dihydroergocryptine: a pseudo-irreversible alpha-adrenergic antagonist in the guinea pig vas deferens

    SciTech Connect

    Wilberding, C.A.; Marks, B.H.

    1981-03-01

    The ergot alkaloid, dihydroergocryptine, exhibits some of the characteristics of a competitive alpha-adrenergic antagonist. Dihydroergocryptine physiological antagonism is surmountable by high concentrations of alpha-adrenergic agonists and (/sup 3/H)-dihydroergocryptine readily binds and dissociates from crude membranes with the characteristics expected of an alpha-adrenoreceptor ligand. However, during physiological studies, dihydroergocryptine antagonism is not readily reversible by washing. To explain this apparently paradoxical behavior of dihydroergocryptine, the characteristic of (/sup 3/H)-dihydroergocryptine accumulation and efflux in the guinea pig vas deferens were studied. Vas deferens segments accumulated 0.99 pmol (/sup 3/H)-dihydroergocryptine/mg protein. Most of the radioligand was extractable by acid-ethanol. About 5-6% of the radioligand remained bound to extracted tissue residues and appeared to be associated with crude membrane fractions prepared from vas deferens segments. Kinetic analysis of (/sup 3/H)-dihydroergocryptine efflux from vas deferens segments indicated the presence of three compartments of radioligand in this tissue. A large compartment of (/sup 3/H)-dihydroergocryptine emptied slowly and may represent radioligand accumulated into the intracellular space. (/sup 3/H)-Dihydroergocryptine also was released from a compartment which exhibited the size and kinetics characteristic of alpha-adrenoreceptor sites on guinea pig vas deferens crude membranes. A small compartment of (/sup 3/H)-dihydroergocryptine was nonexchangeable and nonextractable by acid-ethanol; this nonextractable radioligand may be bound covalently to membrane sites and/or other tissue components.

  19. The turkey erythrocyte beta-adrenergic receptor couples to both adenylate cyclase and phospholipase C via distinct G-protein alpha subunits.

    PubMed Central

    James, S R; Vaziri, C; Walker, T R; Milligan, G; Downes, C P

    1994-01-01

    By contrast with mammalian beta-adrenergic receptors, the avian isoform elicits two distinct effector responses, activation of adenylate cyclase and polyphosphoinositide-specific phospholipase C (PLC) leading to the accumulation of both cyclic adenosine monophosphate (cyclic AMP) and inositol phosphates. We have investigated the mechanisms of beta-adrenergic receptor signalling in turkey erythrocytes. Stimulation of adenylate cyclase by the beta-adrenergic-receptor agonist isoprenaline exhibits a 30-fold lower EC50 than that for PLC activation, which may indicate a marked receptor reserve for the former effector. Similar Ki values were obtained for the inhibition of both responses by four beta-adrenergic antagonists, arguing that a single receptor population is responsible for both effects. Antibodies raised against G-protein peptide sequences were used to show that the identity of the G-protein mediating the PLC response was an avian homologue of G11, the level of expression of which was very similar to that of the stimulatory G-protein of adenylate cyclase, Gs. Thus a single population of beta-adrenergic receptors apparently interacts with distinct G-proteins to activate different effectors. The stoichiometries of the receptor-G-protein-effector interactions are therefore similar for both second-messenger responses and the data are discussed in terms of the different efficacies observed for each response. Images Figure 4 PMID:7998968

  20. Alpha/sub 2/-adrenergic receptors on a platelet precursor cell line, HEL

    SciTech Connect

    McKernan, R.M.; Motulsky, H.J.; Rozansky, D.; Insel, P.A.

    1986-03-01

    The authors have identified ..cap alpha../sub 2/-adrenergic receptors on human erythroleukemia HEL cells, a suspension-growing, bone-marrow-derived cell line related to human platelets. Intact HEL cells were studied using radioligand binding and cAMP accumulation assays. The authors identified saturable specific binding of the ..cap alpha../sub 2/-antagonist (/sup 3/H)yohimbine (yoh) in cells incubated at 37/sup 0/C for 1 hr (B/sub max/ 5900 +/- 2100 sites/cell, K/sub d/ 3.6 +/- 0.9 nM, n = 7). Competition for (/sup 3/H)yoh binding sites with antagonists confirmed that these sites were similar to human ..cap alpha../sub 2/-adrenoceptors from platelets and other resources, as typified by their high affinity for WY-26392, yohimbine and idazoxan, and very low affinity for prazosin. Studies at 37/sup 0/C revealed a low affinity of these sites for catecholamines (K/sub i/ for (-)-epinephrine, 21 ..mu..M; (-)-norepinephrine, 45 ..mu..M, (+)-epinephrine, 80 ..mu..M). When experiments were conducted at 4 /sup 0/C, (-)-epinephrine was able to compete for only 50-60% of the sites specifically labelled by (/sup 3/H)yoh at 37/sup 0/, but (-)-epinephrine had an approximately 10-fold greater affinity for these sites (K/sub i/ at 4 /sup 0/C = 2.4 ..mu..M). In addition, epinephrine inhibited cAMP accumulation stimulated by forskolin and PGE/sub 1/ in HEL cells; this response was inhibited by pertussis toxin. The authors conclude that HEL cells possess ..cap alpha../sub 2/-adrenergic receptors linked to G/sub i/ and thus should serve as a useful model to explore metabolism and regulation of these receptors in human cells.

  1. Modulation of β-Adrenergic Receptor Signaling in Heart Failure and Longevity: Targeting Adenylyl Cyclase Type 5

    PubMed Central

    Ho, David; Yan, Lin; Iwatsubo, Kousaku; Vatner, Dorothy E.; Vatner, Stephen F.

    2011-01-01

    Despite remarkable advances in therapy, heart failure remains a leading cause of morbidity and mortality. Although enhanced β-adrenergic receptor stimulation is part of normal physiologic adaptation to either the increase in physiologic demand or decrease in cardiac function, chronic β-adrenergic stimulation has been associated with increased mortality and morbidity in both animal models and humans. For example, overexpression of cardiac Gsα or β-adrenergic receptors in transgenic mice results in enhanced cardiac function in young animals, but with prolonged overstimulation of this pathway, cardiomyopathy develops in these mice as they age. Similarly, chronic sympathomimetic amine therapy increases morbidity and mortality in patients with heart failure. Conversely, the use of β-blockade has proven to be of benefit and is currently part of the standard of care for heart failure. It is conceivable that interrupting distal mechanisms in the β-adrenergic receptor-G protein-adenylyl cyclase pathway may also provide targets for future therapeutic modalities for heart failure. Interestingly, there are two major isoforms of adenylyl cyclase (AC) in the heart (type 5 and type 6), which may exert opposite effects on the heart, i.e., cardiac overexpression of AC6 appears to be protective, whereas disruption of type 5 AC prolongs longevity and protects against cardiac stress. The goal of this review is to summarize the paradigm shift in the treatment of heart failure over the past 50 years from administering sympathomimetic amine agonists to administering β-adrenergic receptor antagonists, and to explore the basis for a novel therapy of inhibiting type 5 AC. PMID:20658186

  2. Identification and characterization of a novel family of Drosophila beta-adrenergic-like octopamine G-protein coupled receptors.

    PubMed

    Maqueira, Braudel; Chatwin, Heather; Evans, Peter D

    2005-07-01

    Insect octopamine receptors carry out many functional roles traditionally associated with vertebrate adrenergic receptors. These include control of carbohydrate metabolism, modulation of muscular tension, modulation of sensory inputs and modulation of memory and learning. The activation of octopamine receptors mediating many of these actions leads to increases in the levels of cyclic AMP. However, to date none of the insect octopamine receptors that have been cloned have been convincingly shown to be capable of directly mediating selective and significant increases in cyclic AMP levels. Here we report on the identification and characterization of a novel, neuronally expressed family of three Drosophila G-protein coupled receptors that are selectively coupled to increases in intracellular cyclic AMP levels by octopamine. This group of receptors, DmOct beta1R (CG6919), DmOct beta2R (CG6989) and DmOct beta3R (CG7078) shows homology to vertebrate beta-adrenergic receptors. When expressed in Chinese hamster ovary cells all three receptors show a strong preference for octopamine over tyramine for the accumulation of cyclic AMP but show unique pharmacological profiles when tested with a range of synthetic agonists and antagonists. Thus, the pharmacological profile of individual insect tissue responses to octopamine might vary with the combination and the degree of expression of the individual octopamine receptors present. PMID:15998303

  3. Beta3 adrenergic receptor is involved in vascular injury in deoxycorticosterone acetate-salt hypertensive mice.

    PubMed

    Sheng, Li-Juan; Ruan, Cheng-Chao; Ma, Yu; Chen, Dong-Rui; Kong, Ling-Ran; Zhu, Ding-Liang; Gao, Ping-Jin

    2016-03-01

    Beta3 adrenergic receptor (ADRB3) mediates vessel relaxation in the endothelium while it modulates lipolysis in the adipose tissue. However, the function and regulation mechanism of ADRB3 in the perivascular adipose tissue (PVAT), especially in hypertension, is still unclear. We show that ADRB3 protein is upregulated in the PVAT of deoxycorticosterone acetate-salt (DOCA-salt) hypertensive mice, with the characteristics of PVAT browning and increased uncoupling protein 1 (UCP1) expression. Inhibition of ADRB3 with selective antagonist SR59230A caused serious vascular injury in vivo, even though UCP1 expression was downregulated. ADRB3 protein was regulated by let-7b, which was decreased in the PVAT of the DOCA-salt group. These data reveal that ADRB3 in PVAT contributes to vascular function in the progression of hypertension. PMID:26910302

  4. The role of beta-adrenergic receptors in the cutaneous water evaporation mechanism in the heat-acclimated pigeon (Columba livia).

    PubMed

    Ophir, E; Arieli, Y; Raber, P; Marder, J

    2000-01-01

    The effects of selective and non-selective beta-adrenergic agents on cutaneous water evaporation (CWE) were studied in hand-reared rock pigeons (Columba livia). CWE was measured by the vapor diffusive resistance method, using a transient porometer. Intramuscular and subcutaneous injections of a non-selective beta-adrenergic antagonist (propranolol) or a selective beta(2)-adrenergic antagonist (ICI-118551) to heat-acclimated (HAc) pigeons at ambient temperature (T(a)) of 24 degrees C resulted in intensive CWE. The CWE values that were triggered by propranolol and ICI-118551 (18.59+/-0.73 and 16.48+/-0.70 mg cm(-2) h(-1), respectively) were close to those induced by heat exposure (17.62+/-1.40 mg cm(-2) h(-1)). Subcutaneous administration of propranolol produced local response. Intramuscular injection of salbutamol (selective beta(2)-adrenergic agonist) to HAc pigeons drastically diminished CWE induced by either propranolol, metoprolol or heat exposure. Such manipulations also enhanced panting at relatively low T(a)s (42 degrees C). The inhibition of beta(1)-adrenergic receptors by metoprolol increased CWE, while inhibition by atenolol produced no change from basal values. This difference may be attributed to their distinctive nature in penetrating the blood-brain barrier. Our findings indicate a regulatory pathway for CWE consisting of both beta(1)- and beta(2)-adrenergic receptors. We suggest that the beta(1)-adrenergic effect is restricted mainly to the CNS, while the beta(2)-adrenergic effect takes place at the effector level. We postulate this level to be either the cutaneous microvasculature or the epidermal layer. PMID:10779732

  5. β2-Adrenergic receptor supports prolonged theta tetanus-induced LTP.

    PubMed

    Qian, Hai; Matt, Lucas; Zhang, Mingxu; Nguyen, Minh; Patriarchi, Tommaso; Koval, Olha M; Anderson, Mark E; He, Kaiwen; Lee, Hey-Kyoung; Hell, Johannes W

    2012-05-01

    The widespread noradrenergic innervation in the brain promotes arousal and learning by molecular mechanisms that remain largely undefined. Recent work shows that the β(2)-adrenergic receptor (β(2)AR) is linked to the AMPA-type glutamate receptor subunit GluA1 via stargazin and PSD-95 (Joiner ML, Lise MF, Yuen EY, Kam AY, Zhang M, Hall DD, Malik ZA, Qian H, Chen Y, Ulrich JD, Burette AC, Weinberg RJ, Law PY, El-Husseini A, Yan Z, Hell JW. EMBO J 29: 482-495, 2010). We now demonstrate that the β(2)AR plays a prominent role in long-term potentiation (LTP) induced by a train of 900 stimuli at 5 Hz (prolonged theta-tetanus-LTP, or PTT-LTP) in the hippocampal CA1 region in mice, which requires simultaneous β-adrenergic stimulation. Although PTT-LTP was impaired in hippocampal slices from β(1)AR and β(2)AR knockout (KO) mice, only β(2)AR-selective stimulation with salbutamol supported this PTT-LTP in wild-type (WT) slices, whereas β(1)AR-selective stimulation with dobutamine (+ prazosin) did not. Furthermore, only the β(2)AR-selective antagonist ICI-118551 and not the β(1)AR-selective antagonist CGP-20712 inhibited PTT-LTP and phosphorylation of GluA1 on its PKA site S845 in WT slices. Our analysis of S845A knockin (KI) mice indicates that this phosphorylation is relevant for PTT-LTP. These results identify the β(2)AR-S845 signaling pathway as a prominent regulator of synaptic plasticity. PMID:22338020

  6. Housing Temperature-Induced Stress Is Suppressing Murine Graft-versus-Host Disease through β2-Adrenergic Receptor Signaling.

    PubMed

    Leigh, Nicholas D; Kokolus, Kathleen M; O'Neill, Rachel E; Du, Wei; Eng, Jason W-L; Qiu, Jingxin; Chen, George L; McCarthy, Philip L; Farrar, J David; Cao, Xuefang; Repasky, Elizabeth A

    2015-11-15

    Graft-versus-host disease (GVHD) is the major complication of allogeneic hematopoietic cell transplantation, a potentially curative therapy for hematologic diseases. It has long been thought that murine bone marrow-derived T cells do not mediate severe GVHD because of their quantity and/or phenotype. During the course of experiments testing the impact of housing temperatures on GVHD, we discovered that this apparent resistance is a function of the relatively cool ambient housing temperature. Murine bone marrow-derived T cells have the ability to mediate severe GVHD in mice housed at a thermoneutral temperature. Specifically, mice housed at Institutional Animal Care and Use Committee-mandated, cool standard temperatures (∼ 22°C) are more resistant to developing GVHD than are mice housed at thermoneutral temperatures (∼ 30°C). We learned that the mechanism underlying this housing-dependent immunosuppression is associated with increased norepinephrine production and excessive signaling through β-adrenergic receptor signaling, which is increased when mice are cold stressed. Treatment of mice housed at 22°C with a β2-adrenergic antagonist reverses the norepinephrine-driven suppression of GVHD and yields similar disease to mice housed at 30°C. Conversely, administering a β2-adrenergic agonist decreases GVHD in mice housed at 30°C. In further mechanistic studies using β2-adrenergic receptor-deficient (β2-AR(-/-)) mice, we found that it is host cell β2-AR signaling that is essential for decreasing GVHD. These data reveal how baseline levels of β-adrenergic receptor signaling can influence murine GVHD and point to the feasibility of manipulation of β2-AR signaling to ameliorate GVHD in the clinical setting. PMID:26459348

  7. α(2A) adrenergic receptor promotes amyloidogenesis through disrupting APP-SorLA interaction.

    PubMed

    Chen, Yunjia; Peng, Yin; Che, Pulin; Gannon, Mary; Liu, Yin; Li, Ling; Bu, Guojun; van Groen, Thomas; Jiao, Kai; Wang, Qin

    2014-12-01

    Accumulation of amyloid β (Aβ) peptides in the brain is the key pathogenic factor driving Alzheimer's disease (AD). Endocytic sorting of amyloid precursor protein (APP) mediated by the vacuolar protein sorting (Vps10) family of receptors plays a decisive role in controlling the outcome of APP proteolytic processing and Aβ generation. Here we report for the first time to our knowledge that this process is regulated by a G protein-coupled receptor, the α(2A) adrenergic receptor (α(2A)AR). Genetic deficiency of the α(2A)AR significantly reduces, whereas stimulation of this receptor enhances, Aβ generation and AD-related pathology. Activation of α(2A)AR signaling disrupts APP interaction with a Vps10 family receptor, sorting-related receptor with A repeat (SorLA), in cells and in the mouse brain. As a consequence, activation of α(2A)AR reduces Golgi localization of APP and concurrently promotes APP distribution in endosomes and cleavage by β secretase. The α(2A)AR is a key component of the brain noradrenergic system. Profound noradrenergic dysfunction occurs consistently in patients at the early stages of AD. α(2A)AR-promoted Aβ generation provides a novel mechanism underlying the connection between noradrenergic dysfunction and AD. Our study also suggests α(2A)AR as a previously unappreciated therapeutic target for AD. Significantly, pharmacological blockade of the α(2A)AR by a clinically used antagonist reduces AD-related pathology and ameliorates cognitive deficits in an AD transgenic model, suggesting that repurposing clinical α(2A)R antagonists would be an effective therapeutic strategy for AD. PMID:25404298

  8. α2A adrenergic receptor promotes amyloidogenesis through disrupting APP-SorLA interaction

    PubMed Central

    Chen, Yunjia; Peng, Yin; Che, Pulin; Gannon, Mary; Liu, Yin; Li, Ling; Bu, Guojun; van Groen, Thomas; Jiao, Kai; Wang, Qin

    2014-01-01

    Accumulation of amyloid β (Aβ) peptides in the brain is the key pathogenic factor driving Alzheimer’s disease (AD). Endocytic sorting of amyloid precursor protein (APP) mediated by the vacuolar protein sorting (Vps10) family of receptors plays a decisive role in controlling the outcome of APP proteolytic processing and Aβ generation. Here we report for the first time to our knowledge that this process is regulated by a G protein-coupled receptor, the α2A adrenergic receptor (α2AAR). Genetic deficiency of the α2AAR significantly reduces, whereas stimulation of this receptor enhances, Aβ generation and AD-related pathology. Activation of α2AAR signaling disrupts APP interaction with a Vps10 family receptor, sorting-related receptor with A repeat (SorLA), in cells and in the mouse brain. As a consequence, activation of α2AAR reduces Golgi localization of APP and concurrently promotes APP distribution in endosomes and cleavage by β secretase. The α2AAR is a key component of the brain noradrenergic system. Profound noradrenergic dysfunction occurs consistently in patients at the early stages of AD. α2AAR-promoted Aβ generation provides a novel mechanism underlying the connection between noradrenergic dysfunction and AD. Our study also suggests α2AAR as a previously unappreciated therapeutic target for AD. Significantly, pharmacological blockade of the α2AAR by a clinically used antagonist reduces AD-related pathology and ameliorates cognitive deficits in an AD transgenic model, suggesting that repurposing clinical α2AR antagonists would be an effective therapeutic strategy for AD. PMID:25404298

  9. β-Adrenergic receptor stimulation increases surface NKCC2 expression in rat thick ascending limbs in a process inhibited by phosphodiesterase 4.

    PubMed

    Haque, Mohammed Z; Caceres, Paulo S; Ortiz, Pablo A

    2012-11-01

    The thick ascending limb of the loop of Henle (THAL) reabsorbs ∼30% of the filtered NaCl in a process mediated by the apical Na-K-2Cl cotransporter NKCC2. Stimulation of β-adrenergic receptors in the THAL enhances NaCl reabsorption and increases intracellular cAMP. We found that intracellular cAMP stimulates NKCC2 trafficking to the apical membrane via protein kinase A (PKA). Several cAMP-specific phosphodiesterases (PDE) have been identified in rat THALs, and PDE4 decreases cAMP generated by β-adrenergic stimulation in other cells. However, it is not known whether β-adrenergic receptors activation stimulates NKCC2 trafficking. Thus we hypothesized that β-adrenergic receptor stimulation enhances THAL apical membrane NKCC2 expression via the PKA pathway and PDE4 blunts this effect. THAL suspensions were obtained from Sprague-Dawley rats, and surface NKCC2 expression was measured by surface biotinylation and Western blot. Incubation of THALs with the β-adrenergic receptor agonist isoproterenol at 0.5 and 1.0 μM increased surface NKCC2 by 17 ± 1 and 29 ± 5% respectively (P < 0.05). Preventing cAMP degradation with 3-isobutyl-methylxanthine (IBMX; a nonselective phosphodiesterase inhibitor) enhanced isoproterenol-stimulated surface NKCC2 expression to 51 ± 7% (P < 0.05 vs. isoproterenol). The β-adrenergic receptor antagonist propranolol or the PKA inhibitor H-89 completely blocked isoproterenol + IBMX-induced increase on surface NKCC2, while propranolol or H-89 alone had no effect. Selective inhibition of PDE4 with rolipram (20 μM) potentiated the effect of isoproterenol on surface NKCC2 and increased cAMP levels. We concluded that β-adrenergic receptor stimulation enhances surface NKCC2 expression in the THALs via PKA and PDE4 blunts this effect. PMID:22933300

  10. Medicinal chemistry of competitive kainate receptor antagonists.

    PubMed

    Larsen, Ann M; Bunch, Lennart

    2011-02-16

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1-5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure-activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field. PMID:22778857

  11. Crystal Structures of the β2-Adrenergic Receptor

    NASA Astrophysics Data System (ADS)

    Weis, William I.; Rosenbaum, Daniel M.; Rasmussen, Søren G. F.; Choi, Hee-Jung; Thian, Foon Sun; Kobilka, Tong Sun; Yao, Xiao-Jie; Day, Peter W.; Parnot, Charles; Fung, Juan J.; Ratnala, Venkata R. P.; Kobilka, Brian K.; Cherezov, Vadim; Hanson, Michael A.; Kuhn, Peter; Stevens, Raymond C.; Edwards, Patricia C.; Schertler, Gebhard F. X.; Burghammer, Manfred; Sanishvili, Ruslan; Fischetti, Robert F.; Masood, Asna; Rohrer, Daniel K.

    G protein coupled receptors (GPCRs) constitute the largest family of membrane proteins in the human genome, and are responsible for the majority of signal transduction events involving hormones and neuro-transmitters across the cell membrane. GPCRs that bind to diffusible ligands have low natural abundance, are relatively unstable in detergents, and display basal G protein activation even in the absence of ligands. To overcome these problems two approaches were taken to obtain crystal structures of the β2-adrenergic receptor (β2AR), a well-characterized GPCR that binds cate-cholamine hormones. The receptor was bound to the partial inverse agonist carazolol and co-crystallized with a Fab made to a three-dimensional epitope formed by the third intracellular loop (ICL3), or by replacement of ICL3 with T4 lysozyme. Small crystals were obtained in lipid bicelles (β2AR-Fab) or lipidic cubic phase (β2AR-T4 lysozyme), and diffraction data were obtained using microfocus technology. The structures provide insights into the basal activity of the receptor, the structural features that enable binding of diffusible ligands, and the coupling between ligand binding and G-protein activation.

  12. Agonists and antagonists for P2 receptors

    PubMed Central

    Jacobson, Kenneth A.; Costanzi, Stefano; Joshi, Bhalchandra V.; Besada, Pedro; Shin, Dae Hong; Ko, Hyojin; Ivanov, Andrei A.; Mamedova, Liaman

    2015-01-01

    Recent work has identified nucleotide agonists selective for P2Y1, P2Y2 and P2Y6 receptors and nucleotide antagonists selective for P2Y1, P2Y12 and P2X1 receptors. Selective non-nucleotide antagonists have been reported for P2Y1, P2Y2, P2Y6, P2Y12, P2Y13, P2X2/3/P2X3 and P2X7 receptors. For example, the dinucleotide INS 37217 (Up4dC) potently activates the P2Y2 receptor, and the non-nucleotide antagonist A-317491 is selective for P2X2/3/P2X3 receptors. Nucleotide analogues in which the ribose moiety is substituted by a variety of novel ring systems, including conformation-ally locked moieties, have been synthesized as ligands for P2Y receptors. The focus on conformational factors of the ribose-like moiety allows the inclusion of general modifications that lead to enhanced potency and selectivity. At P2Y1,2,4,11 receptors, there is a preference for the North conformation as indicated with (N)-methanocarba analogues. The P2Y1 antagonist MRS2500 inhibited ADP-induced human platelet aggregation with an IC50 of 0.95 nM. MRS2365, an (N)-methanocarba analogue of 2-MeSADP, displayed potency (EC50) of 0.4 nM at the P2Y1 receptor, with >10 000-fold selectivity in comparison to P2Y12 and P2Y13 receptors. At P2Y6 receptors there is a dramatic preference for the South conformation. Three-dimensional structures of P2Y receptors have been deduced from structure activity relationships (SAR), mutagenesis and modelling studies. Detailed three-dimensional structures of P2X receptors have not yet been proposed. PMID:16805423

  13. Glucocorticoids down-regulate beta 1-adrenergic-receptor expression by suppressing transcription of the receptor gene.

    PubMed Central

    Kiely, J; Hadcock, J R; Bahouth, S W; Malbon, C C

    1994-01-01

    The expression of beta 2-adrenergic receptors is up-regulated by glucocorticoids. In contrast, beta 1-adrenergic receptors display glucocorticoid-induced down-regulation. In rat C6 glioma cells, which express both of these subtypes of beta-adrenergic receptors, the synthetic glucocorticoid dexamethasone stimulates no change in the total beta-adrenergic receptor content, but rather shifts the beta 1:beta 2 ratio from 80:20 to 50:50. Radioligand binding and immunoblotting demonstrate a sharp decline in beta 1-adrenergic receptor expression. Metabolic labelling of cells with [35S]-methionine in tandem with immunoprecipitation by beta 1-adrenergic-receptor-specific antibodies reveals a sharp decline in the synthesis of the receptor within 48 h for cells challenged with glucocorticoid. Steady-state levels of beta 1-adrenergic-receptor mRNA declined from 0.47 to 0.26 amol/microgram of total cellular RNA within 2 h of dexamethasone challenge, as measured by DNA-excess solution hybridization. The stability of receptor mRNA was not influenced by glucocorticoid; the half-lives of the beta 1- and beta 2-subtype mRNAs were 1.7 and 1.5 h respectively. Nuclear run-on assays revealed the basis for the down-regulation of receptor expression, i.e. a sharp decline in the relative rate of transcription for the beta 1-adrenergic-receptor gene in nuclei from dexamethasone-treated as compared with vehicle-treated cells. These data demonstrate transcriptional suppression as a molecular explanation for glucocorticoid-induced down-regulation of beta 1-adrenergic receptors. Images Figure 1 Figure 2 Figure 6 PMID:8092990

  14. Chiral recognition in adrenergic receptor binding mimics prepared by molecular imprinting.

    PubMed

    Ramström, O; Yu, C; Mosbach, K

    1996-01-01

    Molecularly imprinted polymers were prepared against the adrenomimetic agents ephedrine and pseudoephedrine. These compounds each incorporate two chiral centres. The polymers were evaluated with respect to enantiodiscrimination of various adrenergic ligands. The selectivity of the polymeric binding sites for the imprinted molecules was very high, and it was found that binding of both the enantiomeric and diastereomeric isomers of the imprint species were effectively obstructed, it was found that these polymers could selectively recognize the enantiomers of the endogenous adrenergic ligand epinephrine as well as several beta-adrenergic blockers. These observations suggest that these polymers effectively mimic the recognition patterns exhibited by natural adrenergic receptors. PMID:9174958

  15. Alpha 2-adrenergic receptor stimulation of phospholipase A2 and of adenylate cyclase in transfected Chinese hamster ovary cells is mediated by different mechanisms

    SciTech Connect

    Jones, S.B.; Halenda, S.P.; Bylund, D.B. )

    1991-02-01

    The effect of alpha 2-adrenergic receptor activation on adenylate cyclase activity in Chinese hamster ovary cells stably transfected with the alpha 2A-adrenergic receptor gene is biphasic. At lower concentrations of epinephrine forskolin-stimulated cyclic AMP production is inhibited, but at higher concentrations the inhibition is reversed. Both of these effects are blocked by the alpha 2 antagonist yohimbine but not by the alpha 1 antagonist prazosin. Pretreatment with pertussis toxin attenuates inhibition at lower concentrations of epinephrine and greatly potentiates forskolin-stimulated cyclic AMP production at higher concentrations of epinephrine. alpha 2-Adrenergic receptor stimulation also causes arachidonic acid mobilization, presumably via phospholipase A2. This effect is blocked by yohimbine, quinacrine, removal of extracellular Ca2+, and pretreatment with pertussis toxin. Quinacrine and removal of extracellular Ca2+, in contrast, have no effect on the enhanced forskolin-stimulated cyclic AMP production. Thus, it appears that the alpha 2-adrenergic receptor in these cells can simultaneously activate distinct signal transduction systems; inhibition of adenylate cyclase and stimulation of phospholipase A2, both via G1, and potentiation of cyclic AMP production by a different (pertussis toxin-insensitive) mechanism.

  16. beta(1)-adrenergic antagonists improve sleep and behavioural disturbances in a circadian disorder, Smith-Magenis syndrome.

    PubMed

    De Leersnyder, H; de Blois, M C; Vekemans, M; Sidi, D; Villain, E; Kindermans, C; Munnich, A

    2001-09-01

    Smith-Magenis syndrome (SMS) is a clinically recognisable contiguous gene syndrome ascribed to interstitial deletions of chromosome 17p11.2. Patients have a phase shift of their circadian rhythm of melatonin with a paradoxical diurnal secretion of the hormone. Serum melatonin levels and day-night behaviour were studied in nine SMS children (aged 4 to 17 years) given acebutolol, a selective beta(1)-adrenergic antagonist (10 mg/kg early in the morning). Cardiac examination, serum melatonin, motor activity recordings, and sleep diaries were monitored before and after drug administration. The present study shows that a single morning dose of acebutolol suppressed the inappropriate secretion of melatonin in SMS. A significant improvement of inappropriate behaviour with increased concentration, delayed sleep onset, increased hours of sleep, and delayed waking were also noted. These results suggest that beta(1)-adrenergic antagonists help to manage hyperactivity, enhance cognitive performance, and reduce sleep disorders in SMS. PMID:11546826

  17. beta. -adrenergic ((/sup 3/H) CGP-12177) receptors are elevated in slices of soleus muscle from CHF 147 dystrophic hamsters

    SciTech Connect

    Watson-Wright, W.M.; Wilkinson, M.

    1987-03-23

    The authors utilized a muscle slice technique to compare the ontogeny of cell surface ..beta..-adrenergic receptor binding in soleus and extensor digitorum longus (EDL) muscles of male Golden Syrian (GS) and Canadian Hybrid Farms 147 (CHF 147) dystrophic hamsters. Binding of the ..beta..-adrenergic antagonist, (/sup 3/H) CGP-12177 (CGP), to GS muscle slices was reversible, saturable, stereospecific and of high affinity. Bmax was higher in the soleus (2.57+/-.12 fmol/mg wet wt) than in the EDL (1.61+/-.17 fmol/mg wet wt) of adult animals while affinities were similar (0.35+/-.06 and 0.24+/-.04 nM respectively). No differences in binding characteristics were seen in EDL of GS compared to CHF 147 animals. In soleus slices from GS hamsters, Bmax was highest at 16 days of age (5.72+/-0.26 fmol/mg), decreased between 16 and 29 days and remained constant until 300 days (2.51+/-0.52 fmol/mg). In dystrophic soleus slices, Bmax was also higher at 16 days than at any other age but receptor number decreased gradually, remaining higher than in GS until 90 days of age (p<0.05). The failure of ..beta..-adrenergic receptor number to decrease at a normal rate may be implicated in the pathogenesis of hamster polymyopathy. 21 references, 5 figures, 1 table.

  18. Data on Arc and Zif268 expression in the brain of the α-2A adrenergic receptor knockout mouse

    PubMed Central

    Sanders, Jeff

    2016-01-01

    The α2-adrenergic receptor (α2-AR) is widely distributed in the brain with distinct roles for α2-AR subtypes (A, B and C). In this article, data are provided on Activity Regulated Cytoskeleton Associated Protein (Arc) and Zif268 expression in the brain of the α2A-AR knockout (α2A-AR KO) mouse. These data are supplemental to an original research article examining Arc and Zif268 expression in rats injected with the α2-AR antagonist, RX821002 (http://dx.doi.org/10.1016/j.neulet.2015.12.002. [1]). PMID:26952134

  19. Data on Arc and Zif268 expression in the brain of the α-2A adrenergic receptor knockout mouse.

    PubMed

    Sanders, Jeff

    2016-06-01

    The α2-adrenergic receptor (α2-AR) is widely distributed in the brain with distinct roles for α2-AR subtypes (A, B and C). In this article, data are provided on Activity Regulated Cytoskeleton Associated Protein (Arc) and Zif268 expression in the brain of the α2A-AR knockout (α2A-AR KO) mouse. These data are supplemental to an original research article examining Arc and Zif268 expression in rats injected with the α2-AR antagonist, RX821002 (http://dx.doi.org/10.1016/j.neulet.2015.12.002. [1]). PMID:26952134

  20. The potential of metabolomic analysis techniques for the characterisation of α1-adrenergic receptors in cultured N1E-115 mouse neuroblastoma cells.

    PubMed

    Wenner, Maria I; Maker, Garth L; Dawson, Linda F; Drummond, Peter D; Mullaney, Ian

    2016-08-01

    Several studies of neuropathic pain have linked abnormal adrenergic signalling to the development and maintenance of pain, although the mechanisms underlying this are not yet fully understood. Metabolomic analysis is a technique that can be used to give a snapshot of biochemical status, and can aid in the identification of the mechanisms behind pathological changes identified in cells, tissues and biological fluids. This study aimed to use gas chromatography-mass spectrometry-based metabolomic profiling in combination with reverse transcriptase-polymerase chain reaction and immunocytochemistry to identify functional α1-adrenergic receptors on cultured N1E-115 mouse neuroblastoma cells. The study was able to confirm the presence of mRNA for the α1D subtype, as well as protein expression of the α1-adrenergic receptor. Furthermore, metabolomic data revealed changes to the metabolite profile of cells when exposed to adrenergic pharmacological intervention. Agonist treatment with phenylephrine hydrochloride (10 µM) resulted in altered levels of several metabolites including myo-inositol, glucose, fructose, alanine, leucine, phenylalanine, valine, and n-acetylglutamic acid. Many of the changes observed in N1E-115 cells by agonist treatment were modulated by additional antagonist treatment (prazosin hydrochloride, 100 µM). A number of these changes reflected what is known about the biochemistry of α1-adrenergic receptor activation. This preliminary study therefore demonstrates the potential of metabolomic profiling to confirm the presence of functional receptors on cultured cells. PMID:26408527

  1. Chemokine (C-X-C Motif) Receptor 4 and Atypical Chemokine Receptor 3 Regulate Vascular α1-Adrenergic Receptor Function

    PubMed Central

    Bach, Harold H; Wong, Yee M; Tripathi, Abhishek; Nevins, Amanda M; Gamelli, Richard L; Volkman, Brian F; Byron, Kenneth L; Majetschak, Matthias

    2014-01-01

    Chemokine (C-X-C motif) receptor (CXCR) 4 and atypical chemokine receptor (ACKR) 3 ligands have been reported to modulate cardiovascular function in various disease models. The underlying mechanisms, however, remain unknown. Thus, it was the aim of the present study to determine how pharmacological modulation of CXCR4 and ACKR3 regulate cardiovascular function. In vivo administration of TC14012, a CXCR4 antagonist and ACKR3 agonist, caused cardiovascular collapse in normal animals. During the cardiovascular stress response to hemorrhagic shock, ubiquitin, a CXCR4 agonist, stabilized blood pressure, whereas coactivation of CXCR4 and ACKR3 with CXC chemokine ligand 12 (CXCL12), or blockade of CXCR4 with AMD3100 showed opposite effects. While CXCR4 and ACKR3 ligands did not affect myocardial function, they selectively altered vascular reactivity upon α1-adrenergic receptor (AR) activation in pressure myography experiments. CXCR4 activation with ubiquitin enhanced α1-AR-mediated vasoconstriction, whereas ACKR3 activation with various natural and synthetic ligands antagonized α1-AR-mediated vasoconstriction. The opposing effects of CXCR4 and ACKR3 activation by CXCL12 could be dissected pharmacologically. CXCR4 and ACKR3 ligands did not affect vasoconstriction upon activation of voltage-operated Ca2+ channels or endothelin receptors. Effects of CXCR4 and ACKR3 agonists on vascular α1-AR responsiveness were independent of the endothelium. These findings suggest that CXCR4 and ACKR3 modulate α1-AR reactivity in vascular smooth muscle and regulate hemodynamics in normal and pathological conditions. Our observations point toward CXCR4 and ACKR3 as new pharmacological targets to control vasoreactivity and blood pressure. PMID:25032954

  2. Antiplatelet therapy: thrombin receptor antagonists

    PubMed Central

    Tello-Montoliu, Antonio; Tomasello, Salvatore D; Ueno, Masafumi; Angiolillo, Dominick J

    2011-01-01

    Activated platelets stimulate thrombus formation in response to rupture of an atherosclerotic plaque or endothelial cell erosion, promoting atherothrombotic disease. Multiple pathways contribute to platelet activation. Aspirin, an irreversible inhibitor of thromboxane A2 synthesis, in combination with clopidogrel, an inhibitor of P2Y12 adenosine diphosphate platelet receptors, represent the current standard-of-care of antiplatelet therapy for patients with acute coronary syndrome and for those undergoing percutaneous coronary intervention. Although these agents have demonstrated significant clinical benefit, the increased risk of bleeding and the recurrence of thrombotic events represent substantial limitations. Thrombin is one of the most important platelet activators. The inhibition of protease-activated receptor 1 showed a good safety profile in preclinical studies. In fact, phase II studies with vorapaxar (SCH530348) and atopaxar (E5555) showed no increase of bleeding events in addition to the current standard-of-care of antiplatelet therapy. Although the results of phase III trials for both drugs are awaited, this family is a promising new addition to the current clinical practice for patients with atherothrombotic disease, not only as an alternative, but also as additional therapy. PMID:21906120

  3. Interactions of. beta. -adrenergic receptors with guanine nucleotide-binding proteins

    SciTech Connect

    Abramson, S.N.

    1985-01-01

    The properties of ..beta..-adrenergic receptors were investigated with radioligand binding assays using the agonists (/sup 3/H)hydroxybenzyl-isoproterenol (/sup 3/H-HBI) and (/sup 3/H)epinephrine (/sup 3/H-EPI), and the antagonist (/sup 125/I)iodopindolol (/sup 125/I-IPIN). Membranes prepared from L6 myoblasts bound (/sup 3/H)HBI, (/sup 3/H)EPI, and (/sup 125/I)IPIN with high affinity and Scatchard plots revealed densities of 222 +/- 23, 111 +/- 7, and 325 +/- 37 fmol/mg of protein, respectively. Binding of (/sup 3/H)HBI and (/sup 3/H)EPI was inhibited allosterically by guanine nucleotides. Membranes prepared from wild-type S49 lymphoma cells bound (/sup 3/H)HBI and (/sup 125/I)IPIN with high affinity and Scatchard plots revealed densities of 48.9 +/- 7.1 and 196 +/- 29 fmol/mg of protein, respectively. Binding of (/sup 3/H)HBI was inhibited allosterically by GTP. Similar results were obtained with membranes prepared from the adenylate cyclase deficient variant of S49 lymphoma cells (cyc-), which does not contain a functional stimulatory guanine nucleotide-binding protein (N/sub s/), but does contain a functional inhibitory guanine nucleotide-binding protein (N/sub i/). Binding of (/sup 3/H)HBI to membranes prepared from cyc- S49 cells was inhibited by pretreatment of cells with pertussis toxin. These results suggest that ..beta..-adrenergic receptors on membranes prepared from cyc- S49 cells interact with N/sub i/ to form a ternary complex composed of agonist, receptor, and N/sub i/.

  4. Effects of ovarian hormones on beta-adrenergic and muscarinic receptors in rat heart

    SciTech Connect

    Klangkalya, B.; Chan, A.

    1988-01-01

    The in vitro and in vivo effects of estrogen and progesterone on muscarinic and ..beta..-adrenergic receptors of cardiac tissue were studied in ovariectomized (OVX) rats. The binding assay for muscarinic receptors was performed under a nonequilibrium condition; whereas the binding assay for ..beta..-adrenergic receptors, under an equilibrium condition. Estrogenic compounds and progesterone were found to have no effect on the binding of the radioligand, (/sup 3/H)-dihydroalprenolol, to ..beta..-adrenergic receptors in vitro. However, progestins but not estrogenic compounds inhibited the binding of the radioligand, (/sup 3/H)-quinuclidinyl benzilate, to muscarinic receptors in vitro, with progesterone as the most potent inhibitor. Progesterone was found to decrease the apparent affinity of muscarinic receptors for (/sup 3/H)(-)QNB in vitro. Daily treatment of OVX rats with estradiol benzoate or progesterone for 4 days had no effect on the muscarinic or ..beta..-adrenergic receptors with respect to the binding affinity and receptor density. However, administrations of these hormones together for 4 days caused an increase in the receptor density of muscarinic receptors without a significant effect on their apparent binding affinity; also these hormones induced a decrease in the binding affinity and an increase in the receptor density of ..beta..-adrenergic receptors.

  5. Optodynamic simulation of β-adrenergic receptor signalling

    PubMed Central

    Siuda, Edward R.; McCall, Jordan G.; Al-Hasani, Ream; Shin, Gunchul; Il Park, Sung; Schmidt, Martin J.; Anderson, Sonya L.; Planer, William J.; Rogers, John A.; Bruchas, Michael R.

    2015-01-01

    Optogenetics has provided a revolutionary approach to dissecting biological phenomena. However, the generation and use of optically active GPCRs in these contexts is limited and it is unclear how well an opsin-chimera GPCR might mimic endogenous receptor activity. Here we show that a chimeric rhodopsin/β2 adrenergic receptor (opto-β2AR) is similar in dynamics to endogenous β2AR in terms of: cAMP generation, MAP kinase activation and receptor internalization. In addition, we develop and characterize a novel toolset of optically active, functionally selective GPCRs that can bias intracellular signalling cascades towards either G-protein or arrestin-mediated cAMP and MAP kinase pathways. Finally, we show how photoactivation of opto-β2AR in vivo modulates neuronal activity and induces anxiety-like behavioural states in both fiber-tethered and wireless, freely moving animals when expressed in brain regions known to contain β2ARs. These new GPCR approaches enhance the utility of optogenetics and allow for discrete spatiotemporal control of GPCR signalling in vitro and in vivo. PMID:26412387

  6. Expression of mammalian beta-adrenergic receptors in Xenopus laevis oocytes

    SciTech Connect

    Bahouth, S.W.; Malbon, C.C.

    1987-05-01

    Xenopus laevis oocytes are a useful transcription and expression system for DNA and RNA, respectively. Total cellular RNA was extracted from mouse lymphoma S49 cells and poly(A)/sup +/mRNA prepared by affinity chromatography of RNA on oligo(dT) cellulose. The membranes of S49 cells contain beta-adrenergic receptors that display pharmacological characteristics of beta/sub 2/-subtype. Xenopus laevis oocytes were injected with 50 ng of mRNA/oocyte. Expression of beta-adrenergic receptors in oocytes incubated for 30 hr after microinjection was assessed in membranes by radioligand binding using (/sup 3/H) dihydroalprenolol. The injected oocytes displayed 0.34 fmol receptor/oocyte as compared to 0.02 fmol receptor/oocyte in the control oocytes. The affinity of beta-adrenergic receptors in injected oocytes for this radioligand was 2 nM, a value similar to the affinity of beta-adrenergic receptors for DHA in S49 cell membranes. The potency of beta-adrenergic agonists in competing for DHA binding to oocytes membranes was isoproterenol > epinephrine > norepineprine, indicating that the expressed beta-adrenergic receptors were of the beta/sub 2/-subtype. The K/sub I/ of these agonists for the beta-adrenergic receptor in oocyte membranes was 0.03, 0.15 and 1.2 ..mu..M, respectively. The role of post-translational modification in dictating receptor subtype is analyzed using mRNA of beta/sub 1/- as well as beta/sub 2/-adrenergic receptors.

  7. Elevated level of. beta. -adrenergic receptors in hepatocytes from regenerating rat liver

    SciTech Connect

    Sandnes, D.; Sand, T.E.; Sager, G.; Broenstad, G.O.; Refsnes, M.R.; Gladhaug, I.P.; Jacobsen, S.; Christoffersen, T.

    1986-01-01

    Hepatocytes from regenerating rat liver show an enhanced epinephrine-sensitive adenylate cyclase activity and cAMP response, which may be involved in triggering of the cell proliferation. We have determined adrenergic receptors and adenylate cyclase activity in hepatocytes isolated at various time points after partial hepatectomy. The number of ..beta..-adrenergic receptors, measured by binding of (/sup 125/I)iodocyanopindolol ((/sup 125/I)CYP) to a particulate fraction prepared from isolated hepatocytes, increased rapidly after partial hepatectomy as compared with sham-operated or untreated controls. The maximal increase, which was observed at 48 h, was between 5- and 6-fold (from approx.1800 to approx.10,500 sites per cell). Thereafter, the number of ..beta..- adrenergic receptors decreased gradually. Competition experiments indicated ..beta../sub 2/-type receptors. Parallelism was found between the change in the number of ..beta../sub 2/-adrenergic receptors and the isoproterenol-responsive adenylate cyclase activity. The number of ..cap alpha../sub 1/-adrenergic receptors, determined by binding of (/sup 3/H)prazosin, was transiently lowered by about 35% at 18-24 h. with no significant change in K/sub d/. Although the results of this study do not exclude the possibility of post-receptor events, they suggest that the increased number of..beta../sub 2/-adrenergic receptors is a major factor responsible for the enhanced catecholamine-responsive adenylate cyclase activity in regenerating liver.

  8. Vanilloid receptors mediate adrenergic nerve- and CGRP-containing nerve-dependent vasodilation induced by nicotine in rat mesenteric resistance arteries

    PubMed Central

    Eguchi, Shinji; Tezuka, Satoko; Hobara, Narumi; Akiyama, Shinji; Kurosaki, Yuji; Kawasaki, Hiromu

    2004-01-01

    Previous studies showed that nicotine induces adrenergic nerve-dependent vasodilation that is mediated by endogenous calcitonin gene-related peptide (CGRP) released from CGRP-containing (CGRPergic) nerves. The mechanisms underlying the nicotine-induced vasodilation were further studied. Rat mesenteric vascular beds without endothelium were contracted by perfusion with Krebs solution containing methoxamine, and the perfusion pressure was measured with a pressure transducer. Perfusion of nicotine (1–100 μM) for 1 min caused concentration-dependent vasodilation. Capsazepine (vanilloid receptor-1 antagonist; 1–10 μM) and ruthenium red (inhibitor of vanilloid response; 1–30 μM) concentration-dependently inhibited the nicotine-induced vasodilation without affecting the vasodilator response to exogenous CGRP. Nicotine-induced vasodilation was not inhibited by treatment with 3,4-dihydroxyphenylalanine (DOPA) receptor antagonist (L-DOPA cyclohexyl ester; 0.001–10 μM), dopamine D1 receptor-selective antagonist (SCH23390; 1–10 μM), dopamine D2 receptor antagonist (haloperidol; 0.1–0.5 μM), ATP P2x receptor-desensitizing agonist (α,β-methylene ATP; 1–10 μM), adenosine A2 receptor antagonist (8(p-sulfophenyl)theophylline; 10–50 μM) or neuropeptide Y (NPY)-Y1 receptor antagonist (BIBP3226; 0.1–0.5 μM). Immunohistochemical staining of the mesenteric artery showed dense innervation of CGRP- and vanilloid receptor-1-positive nerves, with both immunostainings appearing in the same neuron. The mesenteric artery was also densely innervated by NPY-positive nerves. Double immunostainings showed that both NPY and CGRP immunoreactivities appeared in the same neuron of the artery. These results suggest that nicotine acts on presynaptic nicotinic receptors to release adrenergic neurotransmitter(s) or related substance(s), which then stimulate vanilloid receptor-1 on CGRPergic nerves, resulting in CGRP release and vasodilation. PMID:15249421

  9. Vasopressin receptor antagonists: Characteristics and clinical role.

    PubMed

    Rondon-Berrios, Helbert; Berl, Tomas

    2016-03-01

    Hyponatremia, the most common electrolyte disorder in hospitalized patients is associated with increased risk of mortality even when mild and apparently asymptomatic. Likewise morbidity manifested as attention deficits, gait disturbances, falls, fractures, and osteoporosis is more prevalent in hyponatremic subjects. Hyponatremia also generates a significant financial burden. Therefore, it is important to explore approaches that effectively and safely treat hyponatremia. Currently available strategies are physiologically sound and affordable but lack evidence from clinical trials and are limited by variable efficacy, slow response, and/or poor compliance. The recent emergence of vasopressin receptor antagonists provides a class of drugs that target the primary pathophysiological mechanism, namely vasopressin mediated impairment of free water excretion. This review summarizes the historical development, pharmacology, clinical trials supporting efficacy and safety, shortcomings, as well as practical suggestions for the use of vasopressin receptor antagonists. PMID:27156765

  10. Adrenergic DNA damage of embryonic pluripotent cells via β2 receptor signalling

    PubMed Central

    Sun, Fan; Ding, Xu-Ping; An, Shi-Min; Tang, Ya-Bin; Yang, Xin-Jie; Teng, Lin; Zhang, Chun; Shen, Ying; Chen, Hong-Zhuan; Zhu, Liang

    2015-01-01

    Embryonic pluripotent cells are sensitive to genotoxicity though they need more stringent genome integrity to avoid compromising multiple cell lineages and subsequent generations. However it remains unknown whether the cells are susceptible to adrenergic stress which can induce somatic cell genome lesion. We have revealed that adrenergic stress mediators cause DNA damage of the cells through the β2 adrenergic receptor/adenylate cyclase/cAMP/PKA signalling pathway involving an induction of intracellular reactive oxygen species (ROS) accumulation. The adrenergic stress agonists adrenaline, noradrenaline, and isoprenaline caused DNA damage and apoptosis of embryonic stem (ES) cells and embryonal carcinoma stem cells. The effects were mimicked by β2 receptor-coupled signalling molecules and abrogated by selective blockade of β2 receptors and inhibition of the receptor signalling pathway. RNA interference targeting β2 receptors of ES cells conferred the cells the ability to resist the DNA damage and apoptosis. In addition, adrenergic stimulation caused a consistent accumulation of ROS in the cells and the effect was abrogated by β2 receptor blockade; quenching of ROS reversed the induced DNA damage. This finding will improve the understanding of the stem cell regulatory physiology/pathophysiology in an adrenergic receptor subtype signalling mechanism. PMID:26516061

  11. alpha1B-Adrenergic receptor phosphorylation and desensitization induced by transforming growth factor-beta.

    PubMed Central

    Romero-Avila, M Teresa; Flores-Jasso, C Fabián; García-Sáinz, J Adolfo

    2002-01-01

    Transforming growth factor-beta (TGF-beta) induced alpha(1B)-adrenergic receptor phosphorylation in Rat-1 fibroblasts stably expressing these adrenoceptors. This effect of TGF-beta was rapid, reaching a maximum within 30 min and decreasing thereafter, and concentration-dependent (EC(50) 0.3 pM). The phosphoinositide 3-kinase inhibitors wortmannin and LY294002, and the protein kinase C inhibitors staurosporine, Ro 318220 and bisindolylmaleimide, blocked the effect of this growth factor. alpha(1B)-Adrenergic receptor phosphorylation was associated with desensitization, as indicated by a reduction in the adrenergic-mediated production of [(3)H]inositol phosphates. Phosphorylation of alpha(1B)-adrenergic receptors by TGF-beta was also observed in Cos-1 cells transfected with the receptor. Co-transfection of the dominant-negative mutant of the regulatory subunit of phosphoinositide 3-kinase (Deltap85) inhibited the phosphorylation of alpha(1B)-adrenergic receptors induced by TGF-beta. Our results indicate that activation of TGF-beta receptors induces alpha(1B)-adrenergic receptor phosphorylation and desensitization. The data suggest that phosphoinositide 3-kinase and protein kinase C play key roles in this effect of TGF-beta. PMID:12234252

  12. alpha1B-Adrenergic receptor phosphorylation and desensitization induced by transforming growth factor-beta.

    PubMed

    Romero-Avila, M Teresa; Flores-Jasso, C Fabián; García-Sáinz, J Adolfo

    2002-12-01

    Transforming growth factor-beta (TGF-beta) induced alpha(1B)-adrenergic receptor phosphorylation in Rat-1 fibroblasts stably expressing these adrenoceptors. This effect of TGF-beta was rapid, reaching a maximum within 30 min and decreasing thereafter, and concentration-dependent (EC(50) 0.3 pM). The phosphoinositide 3-kinase inhibitors wortmannin and LY294002, and the protein kinase C inhibitors staurosporine, Ro 318220 and bisindolylmaleimide, blocked the effect of this growth factor. alpha(1B)-Adrenergic receptor phosphorylation was associated with desensitization, as indicated by a reduction in the adrenergic-mediated production of [(3)H]inositol phosphates. Phosphorylation of alpha(1B)-adrenergic receptors by TGF-beta was also observed in Cos-1 cells transfected with the receptor. Co-transfection of the dominant-negative mutant of the regulatory subunit of phosphoinositide 3-kinase (Deltap85) inhibited the phosphorylation of alpha(1B)-adrenergic receptors induced by TGF-beta. Our results indicate that activation of TGF-beta receptors induces alpha(1B)-adrenergic receptor phosphorylation and desensitization. The data suggest that phosphoinositide 3-kinase and protein kinase C play key roles in this effect of TGF-beta. PMID:12234252

  13. CENTRAL ADRENERGIC RECEPTOR CHANGES IN THE INHERITED NORADRENERGIC HYPERINNERVATED MUTANT MOUSE TOTTERING (JOURNAL VERSION)

    EPA Science Inventory

    Adrenergic receptor binding characteristics were analyzed in the mutant mouse tottering (tg/tg), a single gene locus autosomal recessive mutation causing hyperinnervation by locus coeuruleus neurons of their target regions, which results in epilepsy. Instead of the expected down-...

  14. Sustained Suppression of Hyperalgesia during Latent Sensitization by μ-, δ-, and κ-opioid receptors and α2A Adrenergic Receptors: Role of Constitutive Activity

    PubMed Central

    Walwyn, Wendy M.; Chen, Wenling; Kim, Hyeyoung; Minasyan, Ani; Ennes, Helena S.; McRoberts, James A.

    2016-01-01

    Many chronic pain disorders alternate between bouts of pain and periods of remission. The latent sensitization model reproduces this in rodents by showing that the apparent recovery (“remission”) from inflammatory or neuropathic pain can be reversed by opioid antagonists. Therefore, this remission represents an opioid receptor-mediated suppression of a sustained hyperalgesic state. To identify the receptors involved, we induced latent sensitization in mice and rats by injecting complete Freund's adjuvant (CFA) in the hindpaw. In WT mice, responses to mechanical stimulation returned to baseline 3 weeks after CFA. In μ-opioid receptor (MOR) knock-out (KO) mice, responses did not return to baseline but partially recovered from peak hyperalgesia. Antagonists of α2A-adrenergic and δ-opioid receptors reinstated hyperalgesia in WT mice and abolished the partial recovery from hyperalgesia in MOR KO mice. In rats, antagonists of α2A adrenergic and μ-, δ-, and κ-opioid receptors reinstated hyperalgesia during remission from CFA-induced hyperalgesia. Therefore, these four receptors suppress hyperalgesia in latent sensitization. We further demonstrated that suppression of hyperalgesia by MORs was due to their constitutive activity because of the following: (1) CFA-induced hyperalgesia was reinstated by the MOR inverse agonist naltrexone (NTX), but not by its neutral antagonist 6β-naltrexol; (2) pro-enkephalin, pro-opiomelanocortin, and pro-dynorphin KO mice showed recovery from hyperalgesia and reinstatement by NTX; (3) there was no MOR internalization during remission; (4) MORs immunoprecipitated from the spinal cord during remission had increased Ser375 phosphorylation; and (5) electrophysiology recordings from dorsal root ganglion neurons collected during remission showed constitutive MOR inhibition of calcium channels. SIGNIFICANCE STATEMENT Chronic pain causes extreme suffering to millions of people, but its mechanisms remain to be unraveled. Latent

  15. Synthesis and characterization of a high affinity radioiodinated probe for the alpha 2-adrenergic receptor

    SciTech Connect

    Lanier, S.M.; Hess, H.J.; Grodski, A.; Graham, R.M.; Homcy, C.J.

    1986-03-01

    The availability of radioiodinated probes has facilitated the localization and molecular characterization of cell membrane receptors for hormones and neurotransmitters. However, such probes are not available for the study of the alpha 2-adrenergic receptor. This report describes the synthesis and characterization of functionalized derivatives of the selective alpha 2-adrenergic antagonists, rauwolscine and yohimbine, which can be radiolabeled to high specific activity with 125I. Following demethylation of rauwolscine or yohimbine, the resultant carboxylic acid derivatives were reacted with 4-aminophenethylamine to yield the respective 4-aminophenethyl carboxamides, 17 alpha-hydroxy-20 alpha-yohimban-16 beta-(N-4-amino-phenethyl)carboxamide (rau-pAPC) and 17 alpha-hydroxy-20 beta-yohimban-16 alpha-(N-4-aminophenethyl)carboxamide. In competitive inhibition studies using rat renal membranes and the radioligand (3H)rauwolscine, rau-pAPC (Ki = 11 +/- 1 nM) exhibited a 14-fold greater affinity than the corresponding yohimbine derivative (Ki = 136 +/- 45 nM). The higher affinity compound, rau-pAPC, was radioiodinated by the chloramine T method, and the product, 125I-rau-pAPC (17 alpha-hydroxy-20 alpha-yohimban-16 beta-(N-4-amino-3 -(125I)iodophenethyl)carboxamide), was purified by reverse phase HPLC to high specific activity (2175 Ci/mmol) and its binding characteristics were investigated in rat kidney membranes. Specific binding of 125I-rau-pAPC was saturable and of high affinity as determined by Scatchard analysis (KD = 1.8 +/- 0.3 nM) or from kinetic studies (KD = k2/k1 = 0.056 +/- 0.013 min-1)/4.3 +/- 0.2 X 10(7) M-1 min-1 = 1.3 +/- 0.3 nM).

  16. Beta-adrenergic receptors of lymphocytes in children with allergic respiratory diseases

    SciTech Connect

    Bittera, I.; Gyurkovits, K.; Falkay, G.; Eck, E.; Koltai, M.

    1988-01-01

    The beta-adrenergic receptor binding sites on peripheral lymphocytes in children with bronchial asthma (n = 16) and seasonal allergic rhinitis (n = 8) were examined in comparison with normal controls (n = 18) by means of /sup 124/I-cyanopindolol. The number of beta-adrenergic receptors was significantly lower in the asthmatic group (858 +/- 460/lymphocyte) than in the controls (1564 +/- 983/lymphocyte). The value (1891 +/- 1502/lymphocyte in children with allergic rhinitis was slightly higher than that in healthy controls. Of the 24 patients suffering from allergic diseases of the lower or upper airways, the bronchial histamine provocation test was performed in 21; 16 gave positive results, while 5 were negative. No difference in beta-adrenergic receptor count was found between the histamine-positive and negative patients. Neither was there any correlation between the number of beta-adrenergic receptors and the high (16/24) and low (8/24) serum IgE concentrations found in allergic patients. The significant decrease in beta-adrenergic receptor count in asthmatic children lends support to Szentivanyi's concept. Further qualitative and quantitative analysis of lymphocyte beta-adrenergic receptors may provide an individual approach to the treatment of bronchial asthma with beta-sympathomimetic drugs.

  17. Possible Mechanisms for Functional Antagonistic Effect of Ferula assafoetida on Muscarinic Receptors in Tracheal Smooth Muscle

    PubMed Central

    Kiyanmehr, Majid; Boskabady, Mohammad Hossein; Khazdair, Mohammad Reza; Hashemzehi, Milad

    2016-01-01

    Background The contribution of histamine (H1) receptors inhibitory and/or β-adrenoceptors stimulatory mechanisms in the relaxant property of Ferula assa-foetida. (F. asafoetida) was examined in the present study. Methods We evaluated the effect of three concentrations of F. asafoetida extract (2.5, 5, and 10 mg/mL), a muscarinic receptors antagonist, and saline on methacholine concentration-response curve in tracheal smooth muscles incubated with β-adrenergic and histamine (H1) (group 1), and only β-adrenergic (group 2) receptors antagonists. Results EC50 values in the presence of atropine, extract (5 and 10 mg/mL) and maximum responses to methacholine due to the 10 mg/mL extract in both groups and 5 mg/mL extract in group 1 were higher than saline (P < 0.0001, P = 0.0477, and P = 0.0008 in group 1 and P < 0.0001, P = 0.0438, and P = 0.0107 in group 2 for atropine, 5 and 10 mg/mL extract, respectively). Values of concentration ratio minus one (CR-1), in the presence of extracts were lower than atropine in both groups (P = 0.0339 for high extract concentration in group 1 and P < 0.0001 for other extract concentrations in both groups). Conclusion Histamine (H1) receptor blockade affects muscarinic receptors inhibitory property of F. asafoetida in tracheal smooth muscle PMID:27540324

  18. Azines as histamine H4 receptor antagonists.

    PubMed

    Lazewska, Dorota; Kiec-Kononowicz, Katarzyna

    2012-01-01

    Since 2000, when the histamine H4 receptor (H4R) was cloned, it has constituted an interesting target for drug development. Pharmacological studies suggest the potential utility of histamine H4R antagonists/inverse agonists in the treatment of inflammatory diseases, e.g. allergic rhinitis, asthma, atopic dermatitis, colitis, or pruritus. The first H4R ligands were non-selective compounds, but intensive chemical and pharmacological work has led to the discovery of highly potent and selective H4R antagonists (e.g. JNJ7777120, CZC-13788, PF-2988403, A-940894, A-987306). The first compound (UR-63325) has finally entered into clinical studies for the treatment of allergic respiratory diseases (completing the phase I ascending dose trial) and has been found to be safe and well tolerated. The number of scientific publications and patent applications in the H4 field is increasing annually. Among the diverse chemical structures of the H4R antagonists described a 2-aminopyrimidine scaffold is repeatedly found. This review looked at recent advances in the search for H4R antagonists as reflected in patent applications/patents and peer-reviewed publications over the last two years. The work concerns azines (mono-, di-, triazines) and their fused analogues. The chemistry and pharmacology has been described. PMID:22202103

  19. Co-translational formation and pharmacological characterization of beta1-adrenergic receptor/nanodisc complexes with different lipid environments.

    PubMed

    Rues, Ralf-Bernhardt; Dötsch, Volker; Bernhard, Frank

    2016-06-01

    G protein-coupled receptors are of key significance for biomedical research. Streamlined approaches for their efficient recombinant production are of pivotal interest in order to explore their intrinsic conformational dynamics and complex ligand binding behavior. We have systematically optimized the co-translational association and folding of G protein-coupled receptors with defined membranes of nanodiscs by cell-free expression approaches. Each optimization step was quantified and the ligand binding active fraction of the receptor samples could drastically be improved. The strategy was exemplified with a stabilized and a non-stabilized derivative of the turkey beta1-adrenergic receptor. Systematic lipid screens with preformed nanodiscs revealed that generation of ligand binding active conformations of the analyzed beta1-adrenergic receptors strongly depends on lipid charge, flexibility and chain length. The lipid composition of the nanodisc membranes modulates the affinities to a variety of ligands of both receptor derivatives. In addition, the thermostabilization procedure had a significant impact on specific ligand affinities of the receptor and abolished or reduced the binding of certain antagonists. Both receptors were highly stable after purification with optimized nanodisc membranes. The procedure avoids any detergent contact of the receptors and sample production takes less than two days. Moreover, even non-stabilized receptors can be analyzed and their prior purification is not necessary for the formation of nanodisc complexes. The established process appears therefore to be suitable as a new platform for the functional or even structural characterization of recombinant G protein-coupled receptors associated with defined lipid environments. PMID:26922884

  20. Alpha 2 adrenergic receptors in hyperplastic human prostate: identification and characterization using (/sup 3/H) rauwolscine

    SciTech Connect

    Shapiro, E.; Lepor, H.

    1986-05-01

    (/sup 3/H)Rauwolscine ((/sup 3/H)Ra), a selective ligand for the alpha 2 adrenergic receptor, was used to identify and characterize alpha 2 adrenergic receptors in prostate glands of men with benign prostatic hyperplasia. Specific binding of (/sup 3/H)Ra to prostatic tissue homogenates was rapid and readily reversible by addition of excess unlabelled phentolamine. Scatchard analysis of saturation experiments demonstrates a single, saturable class of high affinity binding sites (Bmax = 0.31 +/- 0.04 fmol./microgram. DNA, Kd = 0.9 +/- 0.11 nM.). The relative potency of alpha adrenergic drugs (clonidine, alpha-methylnorepinephrine and prazosin) in competing for (/sup 3/H)Ra binding sites was consistent with the order predicted for an alpha 2 subtype. The role of alpha 2 adrenergic receptors in normal prostatic function and in men with bladder outlet obstruction secondary to BPH requires further investigation.

  1. Dihydrotestosterone decreases beta-adrenergic receptor binding in the fetal rabbit lung

    SciTech Connect

    Moawad, A.H.; River, L.P.; River, J.M.

    1988-07-01

    Tritium-labeled dihydroalprenolol was used to quantify the beta-adrenergic receptor sites in day 30 fetal rabbit lung tissue. Each of the fetuses of New Zealand White rabbits on day 28 of gestation was injected with dihydrotestosterone (2.0 micrograms) in one horn of the uterus and 10% ethanol in normal saline (the solvent) in the contralateral one. The animals were sacrificed 48 hours later and the fetal lung tissue was assayed. Dihydrotestosterone decreased the beta-adrenergic receptor site number in the treatment group compared with the control group (86 versus 111 fmol/mg protein, p less than 0.05 by paired t-test). In the presence of dihydrotestosterone, beta-adrenergic receptor binding is inhibited in the preterm fetal rabbit. This effect may be implicated in the beta-adrenergic mediation of phospholipid synthesis and/or release by fetal alveolar cells.

  2. α₁-Adrenergic receptors contribute to the acute effects of 3,4-methylenedioxymethamphetamine in humans.

    PubMed

    Hysek, Cédric M; Fink, Anja E; Simmler, Linda D; Donzelli, Massimiliano; Grouzmann, Eric; Liechti, Matthias E

    2013-10-01

    Preclinical studies implicate a role for α₁-noradrenergic receptors in the effects of psychostimulants, including 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"). The present study evaluated the effects of the α₁-noradrenergic receptor antagonist doxazosin on the acute pharmacodynamic and pharmacokinetic response to MDMA in 16 healthy subjects. Doxazosin (8 mg/d) or placebo was administered for 3 days before MDMA (125 mg) or placebo using a randomized, double-blind, placebo-controlled, 4-session, crossover design. Doxazosin reduced MDMA-induced elevations in blood pressure, body temperature, and moderately attenuated positive mood but enhanced tachycardia associated with MDMA. The results indicate that α₁-adrenergic receptors contribute to the acute cardiostimulant and to a minor extent possibly also to the thermogenic and euphoric effects of MDMA in humans. PMID:23857311

  3. Rational discovery of novel nuclear hormone receptor antagonists

    NASA Astrophysics Data System (ADS)

    Schapira, Matthieu; Raaka, Bruce M.; Samuels, Herbert H.; Abagyan, Ruben

    2000-02-01

    Nuclear hormone receptors (NRs) are potential targets for therapeutic approaches to many clinical conditions, including cancer, diabetes, and neurological diseases. The crystal structure of the ligand binding domain of agonist-bound NRs enables the design of compounds with agonist activity. However, with the exception of the human estrogen receptor-, the lack of antagonist-bound "inactive" receptor structures hinders the rational design of receptor antagonists. In this study, we present a strategy for designing such antagonists. We constructed a model of the inactive conformation of human retinoic acid receptor- by using information derived from antagonist-bound estrogen receptor-α and applied a computer-based virtual screening algorithm to identify retinoic acid receptor antagonists. Thus, the currently available crystal structures of NRs may be used for the rational design of antagonists, which could lead to the development of novel drugs for a variety of diseases.

  4. [The Regulatory Proteins of β-Adrenergic Receptor and Their Functions].

    PubMed

    Tian, Ai-ju; Li, Zi-jian

    2015-04-01

    Vascular diseases has become a top killer of human health, and cardiovascular receptors are pivotal in the occurrence, development, prevention and treatment of cardiovascular diseases. As for the important member of G protein-coupled receptor, β-adrenergic receptor is undoubtedly a most important target of cardiovascular drugs. Being the hot spot in the cardiovascular research and application, β- adrenergic receptor blocker has been considered as the greatest breakthrough for the prevention and cure of cardiovascular disease after digitalis. The 2012 Nobel Prize in chemistry was awarded again to the researchers on β-adrenergic receptors. Extensive researchs show that β-adrenergic receptors are precisely regulated by different regulatory proteins in cells in the transduction of different physiological and pathological signaling pathways. Based on these findings, function-selective ligands recently arise in the receptor research and will be the new chance of drug discovery. In this article we reviewed the related signal pathways and functions of β-adrenergic receptor regulatory proteins. PMID:26201103

  5. Pharmacodynamic properties of leukotriene receptor antagonists.

    PubMed

    Nicosia, S

    1999-06-01

    Leukotrienes (LTs) are among the most important mediators of asthma; cysteine-containing LTs (cysteinyl-LTs, i.e. LTC4, LTD4 and LTE4) are very potent bronchoconstrictors and participate in the inflammatory component of asthma by inducing mucus hypersecretion, plasma extravasation, mucosal oedema and eosinophil recruitment. Therefore, compounds able to inhibit either the formation or the action of LTs are potential antiasthma drugs and, at present, the cysteinyl-LT receptor antagonists (LTRAs) appear to be the most promising. The receptors for cysteinyl-LTs, termed CysLT receptors, are heterogeneous; at least two different classes have so far been recognized, named CysLT1 (blocked by the so-called classical antagonists, such as FPL 55712, ICI 198,615, ICI 204,219, SK&F 104353, MK-476 and others) and CysLT2 (insensitive to the classical antagonists, but sensitive to BAY u9773). The authors' results indicate that even more receptor subclasses might exist in human airways, which discriminate between LTC4 and LTD4, both asthma mediators. Among the many LTRAs, zafirlukast (Accolate, ICI 204,219), montelukast (Singulair, MK-476) and pranlukast (Onon, ONO-1078) are available for clinical use. All the LTRAs are able to inhibit LTD4-induced bronchoconstriction in humans, albeit with different potencies. With respect to antigen challenge, all of them inhibit the early phase of response, whereas only the most recently developed and potent ones are effective in the late phase. LTRAs are effective in asthma triggered by exercise, cold or aspirin. Furthermore, although they are not bronchodilators per se, they increase basal forced expiratory volume in one second in patients with mild-to-moderate asthma, indicating that, in these individuals, constant cysteinyl-LT release contributes to maintaining increased bronchial tone. Finally, the effect of LTRAs is additive to that of beta-agonists and is potentiated by antihistamine compounds. In conclusion, the available results clearly

  6. Cardiac salvage by tweaking with beta-3-adrenergic receptors.

    PubMed

    Balligand, Jean-Luc

    2016-07-15

    Overstimulation of the orthosympathetic system leads to cardiovascular cell and tissue damage through prolonged activation of β-1-2 adrenergic receptors (BARs). The more recent identification of the third isotype of BAR (B3AR) in cardiac myocytes and endothelial cells with a distinctive coupling and effect on cardiac function and remodelling introduced a new facet to this paradigm. In particular, B3AR is up-regulated in cardiac disease and less prone to homologous desensitization, which may reinforce its influence on the diseased myocardium. Mice with transgenic cardiac-specific expression of the human B3AR are protected from cardiac hypertrophy and fibrosis in response to neurohormonal stimulation. B3AR has also been implicated in cardiac protection after ischaemia-reperfusion and the benefits of exercise on the heart. Many of these salvage mechanisms are mediated by B3AR coupling to nitric oxide synthase (eNOS and nNOS) and downstream cGMP/protein kinase G signalling. Notably, B3AR exerts antioxidant protective effects on these and other signalling elements, which may subserve its protective properties in the setting of chronic heart failure. Additional vasorelaxing properties and paracrine NO-mediated signalling by B3AR in endothelium, together with systemic metabolic effects on beige/brown fat complete the pleiotropic protective properties of this new therapeutic target. PMID:27001422

  7. Endothelin receptor antagonists in pulmonary arterial hypertension.

    PubMed

    Dupuis, J; Hoeper, M M

    2008-02-01

    The endothelin (ET) system, especially ET-1 and the ET(A) and ET(B) receptors, has been implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Together with prostanoids and phosphodiesterase 5 inhibitors, ET receptor antagonists have become mainstays in the current treatment of PAH. Three substances are currently available for the treatment of PAH. One of these substances, bosentan, blocks both ET(A) and ET(B) receptors, whereas the two other compounds, sitaxsentan and ambrisentan, are more selective blockers of the ET(A) receptor. There is ongoing debate as to whether selective or nonselective ET receptor blockade is advantageous in the setting of PAH, although there is no clear evidence that receptor selectivity is relevant with regard to the clinical effects of these drugs. For the time being, other features, such as safety profiles and the potential for pharmacokinetic interactions with other drugs used in the treatment of PAH, may be more important than selectivity or nonselectivity when selecting treatments for individual patients. PMID:18238950

  8. Photoaffinity labeling of mammalian. cap alpha. /sub 1/-adrenergic receptors: identification of the ligand binding subunit with a high affinity radioiodinated probe. [Rats, guinea pigs, rabbits

    SciTech Connect

    Leeb-Lundberg, L.M.F.; Dickinson, K.E.J.; Heald, S.L.; Wikberg, J.E.S.; Hagen, P.O.; DeBernardis, J.F.; Winn, M.; Arendsen, D.L.; Lefkowitz, R.J.; Caron, M.G.

    1984-02-01

    A description is given of the synthesised and characterization of a novel high affinity radioiodinated ..cap alpha../sub 1/-adrenergic receptor photoaffinity probe, 4-amino-6,7-dimethoxy-2-(4-(5-(4-azido-3-(/sup 125/I)iodophenyl)pentanoyl)-1-piperazinyl) quinazoline. In the absence of light, this ligand binds with high affinity (K/sub d/ = 130 pm) in a reverisble and saturable manner to sites in rat hepatic plasma membranes. The binding is stereoselective and competitively inhibited by adrenergic agonists and antagonists with an ..cap alpha../sub 1/-adrenergic specificity. Upon photolysis, this ligand incorporates irreversibly into plasma membranes prepared from several mammalian tissues including rat liver, rat, guinea pig, and rabbit spleen, rabbit lung, and rabbit aorta vascular smooth muscle cells, also with typical ..cap alpha../sub 1/-adrenergic specificity. Autoradiograms of such membrane samples subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveal a major specifically labeled polypeptide at M/sub 4/ = 78,000-85,000, depending on the tissue used, in addition to some lower molecular weight peptides. Protease inhibitors, in particular EDTA, a metalloprotease inhibitor, dramatically increases the predominance of the M/sub r/ = 78,000-85,000 polypeptide while attenuating the labeling of the lower molecular weight bands. This new high affinity radioiodinated photoaffinity probe should be of great value for the molecular characterization of the ..cap alpha../sub 1/-adrenergic receptor.

  9. Carvedilol binding to β2-adrenergic receptors inhibits CFTR-dependent anion secretion in airway epithelial cells.

    PubMed

    Peitzman, Elizabeth R; Zaidman, Nathan A; Maniak, Peter J; O'Grady, Scott M

    2016-01-01

    Carvedilol functions as a nonselective β-adrenergic receptor (AR)/α1-AR antagonist that is used for treatment of hypertension and heart failure. Carvedilol has been shown to function as an inverse agonist, inhibiting G protein activation while stimulating β-arrestin-dependent signaling and inducing receptor desensitization. In the present study, short-circuit current (Isc) measurements using human airway epithelial cells revealed that, unlike β-AR agonists, which increase Isc, carvedilol decreases basal and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate-stimulated current. The decrease in Isc resulted from inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR). The carvedilol effect was abolished by pretreatment with the β2-AR antagonist ICI-118551, but not the β1-AR antagonist atenolol or the α1-AR antagonist prazosin, indicating that its inhibitory effect on Isc was mediated through interactions with apical β2-ARs. However, the carvedilol effect was blocked by pretreatment with the microtubule-disrupting compound nocodazole. Furthermore, immunocytochemistry experiments and measurements of apical CFTR expression by Western blot analysis of biotinylated membranes revealed a decrease in the level of CFTR protein in monolayers treated with carvedilol but no significant change in monolayers treated with epinephrine. These results demonstrate that carvedilol binding to apical β2-ARs inhibited CFTR current and transepithelial anion secretion by a mechanism involving a decrease in channel expression in the apical membrane. PMID:26566905

  10. Novel paramagnetic AT1 receptor antagonists.

    PubMed

    Tan, Nichole P H; Taylor, Michelle K; Bottle, Steven E; Wright, Christine E; Ziogas, James; White, Jonathan M; Schiesser, Carl H; Jani, Nitya V

    2011-11-28

    Novel paramagnetic selective angiotensin AT(1) receptor antagonists (sartans) bearing nitroxides (3, 4) have been prepared and their pharmacology evaluated in vitro as well as in vivo. Compounds 3, 4 proved to be effective sartans with pK(B) estimates in the range 6.2-9.1. In addition, the sodium salt (11) of 4 (R = Bu) is able to protect against vascular injury in hypertensive rats as determined by its ability to attenuate the development of intimal thickening caused by balloon injury of the carotid artery. PMID:21963998

  11. Mineralocorticoid receptor antagonists and endothelial function

    PubMed Central

    Maron, Bradley A.; Leopold, Jane A.

    2010-01-01

    Hyperaldosteronism has been associated with endothelial dysfunction and impaired vascular reactivity in patients with hypertension or congestive heart failure. The mineralocorticoid receptor (MR) antagonists spironolactone and eplerenone have been shown to reduce morbidity and mortality, in part, by ameliorating the adverse effects of aldosterone on vascular function. Although spironolactone and eplerenone are increasingly utilized in patients with cardiovascular disease, widespread clinical use is limited by the development of gynecomastia with spironolactone and hyperkalemia with both agents. This suggests that the development of newer agents with favorable side effect profiles is warranted. PMID:18729003

  12. Localization of beta-adrenergic receptors on differentiated cells of the central nervous system in culture.

    PubMed Central

    Ventimiglia, R; Greene, M I; Geller, H M

    1987-01-01

    Hypothalamic neurons and cortical protoplasmic (type 1) astrocytes in dissociated cultures of rat brain express binding sites for antibodies specific for epitopes related to the beta-adrenergic receptor. Undifferentiated glial progenitor cells of the rat optic nerve do not detectably bind these antibodies, but both of the progeny [oligodendroglia and process-bearing (type 2) astrocytes] express immunologically identified beta-adrenergic receptors. Levels of receptor expression are variable: not all cells of each type express receptors nor is expression uniform on a given cell. The data suggest that cells of the central nervous system express beta-adrenergic receptors but that levels of expression may be determined by the differentiated state of the cells. Images PMID:3037533

  13. Cloning and expression of a human kidney cDNA for an /alpha//sub 2/-adrenergic receptor subtype

    SciTech Connect

    Regan, J.W.; Kobilka, T.S.; Yang-Feng, T.L.; Caron, M.G.; Lefkowitz, R.J.; Kobilka, B.K.

    1988-09-01

    An /alpha//sub 2/-adrenergic receptor subtype has been cloned from a human kidney cDNA library using the gene for the human platelet /alpha//sub 2/-adrenergic receptor as a probe. The deduced amino acid sequence resembles the human platelet /alpha//sub 2/-adrenergic receptor and is consistent with the structure of other members of he family of guanine nucleotide-binding protein-coupled receptors. The cDNA was expressed in a mammalian cell line (COS-7), and the /alpha//sub 2/-adrenergic ligand (/sup 3/H)rauwolscine was bound. Competition curve analysis with a variety of adrenergic ligands suggests that this cDNA clone represents the /alpha//sub 2/B-adrenergic receptor. The gene for this receptor is on human chromosome 4, whereas the gene for the human platelet /alpha//sub 2/-adrenergic receptor (/alpha//sub 2/A) lies on chromosome 10. This ability to express the receptor in mammalian cells, free of other adrenergic receptor subtypes, should help in developing more selective /alpha/-adrenergic ligands.

  14. [Beta]-Adrenergic Receptors in the Insular Cortex are Differentially Involved in Aversive vs. Incidental Context Memory Formation

    ERIC Educational Resources Information Center

    Miranda, Maria Isabel; Sabath, Elizabeth; Nunez-Jaramillo, Luis; Puron-Sierra, Liliana

    2011-01-01

    The goal of this research was to determine the effects of [beta]-adrenergic antagonism in the IC before or after inhibitory avoidance (IA) training or context pre-exposure in a latent inhibition protocol. Pretraining intra-IC infusion of the [beta]-adrenergic antagonist propranolol disrupted subsequent IA retention and impaired latent inhibition…

  15. Norepinephrine increases NADPH oxidase-derived superoxide in human peripheral blood mononuclear cells via α-adrenergic receptors

    PubMed Central

    Deo, Shekhar H.; Jenkins, Nathan T.; Padilla, Jaume; Parrish, Alan R.

    2013-01-01

    Many diseases associated with sympathoexcitation also exhibit elevated reactive oxygen species (ROS). A recent animal study indicated that exogenous administration of the sympathetic neurotransmitter norepinephrine (NE) increased systemic ROS via circulating leukocytes. The mechanisms contributing to this effect of NE and whether these findings can be translated to humans is unknown. Thus we tested the hypothesis that NE increases superoxide production in human peripheral blood mononuclear cells (PBMCs) via NADPH oxidase. Primary human PBMCs were freshly isolated from healthy young men and placed in culture. After NE (50 pg/ml, 50 ng/ml, and 50 μg/ml concentrations) or control treatments, NADPH oxidase mRNA expression (gp91phox, p22phox, and p67phox) was assessed using real-time RT-PCR, and intracellular superoxide production was measured using dihydroethidium fluorescence. PBMCs were also treated with selective adrenergic agonists-antagonists to determine the receptor population involved. In addition, CD14+ monocyte-endothelial cell adhesion was determined using a fluorescent-based assay. NE significantly increased NADPH oxidase gene expression and intracellular superoxide production in a time-dependent manner (superoxide: 0.9 ± 0.2 fold, 6 h vs. 3.0 ± 0.3 fold, 36 h; NE, 50 μg/ml; P < 0.05). The sustained increase in NE-induced superoxide production was primarily mediated via α-adrenergic receptors, preferentially α2-receptors. The NADPH oxidase blocker diphenylene iodonium and protein kinase C inhibitor Staurosporine significantly attenuated NE-induced increases in superoxide production. Importantly, NE treatment increased CD14+ monocyte-endothelial cell adhesion. These findings indicate for the first time that NE increases superoxide production in freshly isolated primary human PBMCs via NADPH oxidase through α-adrenergic receptors, an effect facilitating monocyte adhesion to the endothelium. PMID:24068047

  16. G-receptor antagonists increased the activating effect of mastoparan on low Km GTPase of mouse PAG.

    PubMed

    Martínez-Peña, Y; Sánchez-Blázquez, P; Garzón, J

    1995-02-01

    Mastoparan activated in a concentration-dependent manner the low Km GTPase activity in P2 fractions from mouse periaquedultal grey matter (PAG). This peptide at 1-10 mM produced increases of 30-70% over the basal value of 90-120 pmol Pi/mg/min. A series of substances displaying antagonist activity at cellular receptors and not modifying the GTPase function, when used at nanomolar and micromolar concentrations enhanced the effect of mastoparan upon this enzyme. These included antagonists of receptors coupling G proteins: naloxone (non selective opioid antagonist), CTOP (m opioid receptors), ICI 174,864 (d opioid receptors), nor-BNI (k opioid receptors), sulpiride (D2 dopaminergic antagonist), idazoxan (a2 adrenergic antagonist). Bicuculline, antagonist of a receptor not linked to G proteins, GABAA, did not alter the effect of mastoparan on the GTPase. The m opioid agonist, DAMGO, prevented naloxone from increasing the function of the mastoparan-activated enzyme. Thus, mastoparan appears to act on Gi/Go proteins at a site not directly related to the receptor binding domain. PMID:7794687

  17. Effects of phorbol esters on adrenergic receptors of DDT MF-2 smooth muscle cells

    SciTech Connect

    Cowlen, M.; Toews, M.

    1986-03-05

    Phorbol esters have been reported to induce redistribution or internalization of several types of cell surface receptors, including beta-adrenergic receptors (BAR) in some cells. They investigated the effects of phorbol esters on adrenergic receptor distribution in DDT/sub 1/ MF-2 smooth muscle cells in suspension culture. Exposure of cells to epinephrine, an agonist for both BAR and alpha-1 adrenergic receptors (AAR), led to a shift of about half of BAR from plasma membrane to light vesicle fractions on sucrose density gradient centrifugation. This change correlates with other evidence for internalization or sequestration of BAR away from the cell surface. AAR distribution remained unaltered following agonist treatment. Pretreatment of cells with phorbol 12-myristate 13-acetate, which caused about 80% inhibition of epinephrine-stimulated turnover of inositol phospholipids, did not lead to redistribution of either BAR or AAR.

  18. alpha. - and. beta. -adrenergic receptors in proximal tubules of rat kidney

    SciTech Connect

    Sundaresan, P.R.; Fortin, T.L.; Kelvie, S.L. )

    1987-11-01

    Proximal tubules were isolated from the rat kidney by collagenase digestion of the cortical tissue followed by Percoll gradient centrifugation. Microscopic and hormone-stimulated adenylate cyclase activity studies proved the purity of the preparation. ({sup 3}H)Prazosin, ({sup 3}H)rauwolscine, and ({sup 125}I)iodocyanopindolol were used to identify and quantitate respectively the {alpha}{sub 1}-, {alpha}{sub 2}- and {beta}-adrenergic receptors. Proximal tubular (F{sub 4}) particulate fraction was compared against other cortical nephron segment (F{sub 1},F{sub 2}) fractions and the total collagenase-digested cortex particulate suspension (F{sub t}). Proximal tubules were enriched in {alpha}{sub 1}- and {alpha}{sub 2}-adrenergic receptors compared with. The fractions enriched in glomeruli and distal tubular segments had relatively low concentrations of {alpha}{sub 1}- and {alpha}{sub 2}-adrenergic receptors. Isoproterenol-stimulated adenylate cyclase activities in the different fractions corroborated well with the pattern suggested by the ({sup 125}I)iodocyanopindolol binding studies. The results suggest that whole-cortex preparation radioligand binding studies may reflect proximal tubular {alpha}{sub 1}- and {alpha}{sub 2}-adrenergic receptor changes quite well. They may, however, miss or give erroneous impressions about {beta}-adrenergic receptor changes occurring in different cortical nephron segments.

  19. A role for α1-adrenergic receptors in extinction of conditioned fear and cocaine conditioned preference

    PubMed Central

    Bernardi, Rick E.; Lattal, K. Matthew

    2010-01-01

    Previous work has demonstrated an important role for adrenergic receptors in memory processes in fear and drug conditioning paradigms. Recent studies have also demonstrated alterations in extinction in these paradigms using drug treatments targeting β- and α2-adrenergic receptors, but little is known about the role of α1-adrenergic receptors in extinction. The current study examined whether antagonism of α1-adrenergic receptors would impair the consolidation of extinction in fear and cocaine conditioned place preference (CPP) paradigms. After contextual fear conditioning, injections of prazosin (1.0 or 3.0 mg/kg) following nonreinforced context exposures slowed the loss of conditioned freezing over the course of five extinction sessions (Experiment 1). After cocaine place conditioning, prazosin had no effect on the rate of extinction over eight nonreinforced test sessions. Following post-extinction reconditioning, however, prazosin-treated mice showed a robust place preference, but vehicle-treated mice did not, suggesting that prazosin reduced the persistent effects of extinction (Experiment 2). These results confirm the involvement of the α1-adrenergic receptor in extinction processes in both appetitive and aversive preparations. PMID:20364880

  20. Dephosphorylation of the beta 2-adrenergic receptor and rhodopsin by latent phosphatase 2

    SciTech Connect

    Yang, S.D.; Fong, Y.L.; Benovic, J.L.; Sibley, D.R.; Caron, M.G.; Lefkowitz, R.J.

    1988-06-25

    Recent evidence suggests that the function of receptors coupled to guanine nucleotide regulatory proteins may be controlled by highly specific protein kinases, e.g. rhodopsin kinase and the beta-adrenergic receptor kinase. In order to investigate the nature of the phosphatases which might be involved in controlling the state of receptor phosphorylation we studied the ability of four highly purified well characterized protein phosphatases to dephosphorylate preparations of rhodopsin or beta 2-adrenergic receptor which had been highly phosphorylated by beta-adrenergic receptor kinase. These included: type 1 phosphatase, calcineurin phosphatase, type 2A phosphatase, and the high molecular weight latent phosphatase 2. Under conditions in which all the phosphatases could dephosphorylate such common substrates as (/sup 32/P)phosphorylase a and (/sup 32/P)myelin basic protein at similar rates only the latent phosphatase 2 was active on the phosphorylated receptors. Moreover, a latent phosphatase activity was found predominantly in a sequestered membrane fraction of frog erythrocytes. This parallels the distribution of a beta-adrenergic receptor phosphatase activity recently described in these cells. These data suggest a potential role for the latent phosphatase 2 as a specific receptor phosphatase.

  1. Beta-Adrenergic Receptor Expression in Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, Ronald B.; Bridge, K.; Vaughn, J. R.

    1999-01-01

    beta-adrenergic receptor (bAR) agonists presumably exert their physiological action on skeletal muscle cells through the bAR. Since the signal generated by the bAR is cyclic AMP (cAMP), experiments were initiated in primary chicken muscle cell cultures to determine if artificial elevation of intracellular cAMP by treatment with forskolin would alter the population of bAR expressed on the surface of muscle cells. Chicken skeletal muscle cells after 7 days in culture were employed for the experiments because muscle cells have attained a steady state with respect to muscle protein metabolism at this stage. Cells were treated with 0-10 uM forskolin for a total of three days. At the end of the 1, 2, and 3 day treatment intervals, the concentration of cAMP and the bAR population were measured. Receptor population was measured in intact muscle cell cultures as the difference between total binding of [H-3]CGP-12177 and non-specific binding of [H-3]CGP-12177 in the presence of 1 uM propranolol. Intracellular cAMP concentration was measured by radioimmunoassay. The concentration of cAMP in forskolin-treated cells increased up to 10-fold in a dose dependent manner. Increasing concentrations of forskolin also led to an increase in (beta)AR population, with a maximum increase of approximately 50% at 10 uM. This increase in (beta)AR population was apparent after only 1 day of treatment, and the pattern of increase was maintained for all 3 days of the treatment period. Thus, increasing the intracellular concentration of cAMP leads to up-regulation of (beta)AR population. Clenbuterol and isoproterenol gave similar effects on bAR population. The effect of forskolin on the quantity and apparent synthesis rate of the heavy chain of myosin (mhc) were also investigated. A maximum increase of 50% in the quantity of mhc was observed at 0.2 UM forskolin, but higher concentrations of forskolin reduced the quantity of mhc back to control levels.

  2. Cloning and expression of a rat brain. alpha. sub 2B -adrenergic receptor

    SciTech Connect

    Flordellis, C.S.; Handy, D.E.; Bresnahan, M.R.; Zannis, V.I.; Gavras, H. )

    1991-02-01

    The authors isolated a cDNA clone (RB{alpha}{sub 2B}) and its homologous gene (GR{alpha}{sub 2B}) encoding an {alpha}{sub 2B}-adrenergic receptor subtype by screening a rat brain cDNA and a rat genomic library. Nucleotide sequence analysis showed that both clones code for a protein of 458 amino acids, which is 87% homologous to the human kidney glycosylated adrenergic receptor ({alpha}{sub 2}-C4) and divergent from the rat kidney nonglycosylated {alpha}{sub 2B} subtype (RNG{alpha}{sub 2}). Transient expression of RB{alpha}{sub 2B} in COS-7 cells resulted in high-affinity saturable binding for ({sup 3}H)rauwolscine and a high receptor number in the membranes of transfected COS-7 cells. Pharmacological analysis demonstrated that the expressed receptor bound adrenergic ligands with the following order of potency: rauwolscine {gt} yohimbine {gt} prazosin {gt} oxymetazoline, with a prazosin-to-oxymetazoline K{sub i} ratio of 0.34. This profile is characteristic of the {alpha}{sub 2B}-adrenergic receptor subtype. Blotting analysis of rat brain mRNA gave one major and two minor mRNA species, and hybridization with strand-specific probes showed that both DNA strands of GR{alpha}{sub 2B} may be transcriptionally active. These findings show that rat brain expresses an {alpha}{sub 2B}-adrenergic receptor subtype that is structurally different from the rat kidney nonglycosylated {alpha}{sub 2B} subtype. Thus the rat expresses at least two divergent {alpha}{sub 2B}-adrenergic receptors.

  3. p-( sup 125 I)iodoclonidine, a novel radiolabeled agonist for studying central alpha 2-adrenergic receptors

    SciTech Connect

    Baron, B.M.; Siegel, B.W. )

    1990-09-01

    Unlabeled p-iodoclonidine was efficacious in attenuating forskolin-stimulated cAMP accumulation in SK-N-SH neuroblastoma cells. Maximal attenuation was 76 +/- 3%, with an EC50 of 347 +/- 60 nM. Comparable values of epinephrine were 72 +/- 3% and 122 +/- 22 nM. Responses to both agonists were abolished by 10 microM phentolamine. Therefore, p-iodoclonidine is an agonist in a cell culture model system of the neuronal alpha 2-adrenergic receptor. p-(125I)Iodoclonidine binding to membranes were measured using various regions of the rat brain. The agonist labeled a single population of sites present on cerebral cortical membranes, which was saturable (Bmax = 230 fmol/mg of protein) and possessed high affinity for the ligand (Kd = 0.6 nM). Binding was largely specific (93% at 0.6 nM). A variety of alpha 2-adrenergic agonists and antagonists were shown to compete for the binding of the radioligand. The binding of p-(125I)iodoclonidine was much less sensitive to agents that interact with alpha 1-adrenergic, serotonergic, and dopaminergic receptors. Approximately 65% of the binding was sensitive to guanine nucleotides. Association kinetics using 0.4 nM radioligand were biphasic (37% associate rapidly, with kobs = 0.96 min-1, with the remainder binding more slowly, with kobs = 0.031 min-1) and reached a plateau by 90 min at 25 degrees. Dissociation kinetics were also biphasic, with 30% of the binding dissociating rapidly (k1 = 0.32 min-1) and the remainder dissociating 50-fold more slowly (k2 = 0.006 min-1). Agonist binding is, therefore, uniquely complex and probably reflects the conformational changes that accompany receptor activation.

  4. Beta-2 adrenergic receptor genotypes and haplotypes in different ethnic groups.

    PubMed

    Maxwell, Taylor J; Ameyaw, Margaret-Mary; Pritchard, Stuart; Thornton, Nadia; Folayan, Gbolahan; Githang'a, Jessie; Indalo, Anne; Tariq, Mohammed; Mobarek, Abeer; Evans, David A; Ofori-Adjei, David; Templeton, Alan R; McLeod, Howard L

    2005-10-01

    The human beta-2 adrenergic receptor (beta2AR) is responsible for the binding of endogenous catecholamines and their exogenously administered agonists and antagonists. Three functional polymorphisms in codons 16, 27 and 164 have been described which have clinical importance for several diseases, including asthma, hypertension, heart failure, cystic fibrosis and obesity, as well as response to beta-agonist therapy. These were evaluated in 726 individuals from 8 distinct ethnic populations (Chinese, Filipino, Southwest Asian, Saudi, Ghanaian, Kenyan, Sudanese, and European from Scotland). The results show that most haplotypes are shared among all populations, yet there are marked differences in their frequency distributions geographically. The genetic distance tree is different from standard human population distance trees, implying a different mode of evolution for this locus than that for human population gene-flow history. The multilocus frequency differences between the observed clusters of populations correspond to historical haplotype groupings that have been found to be functionally different with respect to multiple medically related phenotypes. Further studies are needed to see if functional relationships are the same across populations. PMID:16142389

  5. beta. -adrenergic receptor binding characteristics and responsiveness in cultured Wistar-Kyoto rat arterial smooth muscle cells

    SciTech Connect

    Jazayeri, A.; Meyer, W.J. III

    1988-01-01

    The tone of arterial blood vessels is regulated by the catecholamines through their receptors on arterial smooth muscle cells (ASMC). ..beta..-/sub 2/-adrenergic receptors of ASMC mediate vasodilation through agonist mediated c-AMP production. Previous reports have described these receptors on freshly isolated blood vessels. This study demonstrates the presence of ..beta../sub 2/-adrenergic receptors on cultured rat ASMC and that these receptors are functional. ..beta..-adrenergic receptor binding was measured using (/sup 3/H)-dihydroalprenolol (DHA) binding to the membrane of cultured ASMC from normotensive Wistar-Kyoto rats. The ASMC ..beta..-adrenergic receptors have a Kd of 0.56 +/- 0.16 nM and a Bmax of 57.2 +/- 21.7 fmol/mg protein. Competition binding studies revealed a much greater affinity of these receptors for epinephrine than norepinephrine, indicating the preponderance of a ..beta../sub 2/-adrenergic receptor subtype. Isoproterenol stimulation of cultured ASMC resulted in a 14 +/- 7 fold increase in intracellular c-AMP content of these cells indicating these receptors are functional. ..beta..-adrenergic receptors of cultured ASMC provide an excellent system in which the association between hypertension and observed ..beta..-adrenergic receptor differences can be further explored.

  6. Targeting of Beta Adrenergic Receptors Results in Therapeutic Efficacy against Models of Hemangioendothelioma and Angiosarcoma

    PubMed Central

    Stiles, Jessica M.; Amaya, Clarissa; Rains, Steven; Diaz, Dolores; Pham, Robert; Battiste, James; Modiano, Jaime F.; Kokta, Victor; Boucheron, Laura E.; Mitchell, Dianne C.; Bryan, Brad A.

    2013-01-01

    Therapeutic targeting of the beta-adrenergic receptors has recently shown remarkable efficacy in the treatment of benign vascular tumors such as infantile hemangiomas. As infantile hemangiomas are reported to express high levels of beta adrenergic receptors, we examined the expression of these receptors on more aggressive vascular tumors such as hemangioendotheliomas and angiosarcomas, revealing beta 1, 2, and 3 receptors were indeed present and therefore aggressive vascular tumors may similarly show increased susceptibility to the inhibitory effects of beta blockade. Using a panel of hemangioendothelioma and angiosarcoma cell lines, we demonstrate that beta adrenergic inhibition blocks cell proliferation and induces apoptosis in a dose dependent manner. Beta blockade is selective for vascular tumor cells over normal endothelial cells and synergistically effective when combined with standard chemotherapeutic or cytotoxic agents. We demonstrate that inhibition of beta adrenergic signaling induces large scale changes in the global gene expression patterns of vascular tumors, including alterations in the expression of established cell cycle and apoptotic regulators. Using in vivo tumor models we demonstrate that beta blockade shows remarkable efficacy as a single agent in reducing the growth of angiosarcoma tumors. In summary, these experiments demonstrate the selective cytotoxicity and tumor suppressive ability of beta adrenergic inhibition on malignant vascular tumors and have laid the groundwork for a promising treatment of angiosarcomas in humans. PMID:23555867

  7. Homology modeling and antagonist binding site study of the human histamine H2 receptor.

    PubMed

    Zhang, Jing; Qi, Tao; Wei, Jing

    2012-11-01

    On the basis of the high resolution crystal structures of bovine rhodopsin, human beta2-adrenergic receptor and human A(2a) adenosine receptor, three-dimensional structure of the human histamine H2 receptor (HHR2) was developed by homology modeling. Results of the evaluations suggest that a high quality homology model for HHR2 has been obtained. Three antagonists, cimetidine, ranitidine and nizatidine, were applied to binding site study with this model through molecular docking, molecular dynamics simulations and the molecular mechanics-Poisson-Boltzmann surface area calculations. One aspartic acid, Asp98 in transmembrane domain 7 (TM3), has been identified as major contributors to ligand binding by H-bond interactions. Asn159 in TM4 and Asp186 in TM5 are of great importance in stabilizing HHR2- antagonist complexes. Two hydrophobic sites especially two residues, Val99 in TM3 and Phe254 in TM6, were identified to be essential for their strong hydrophobic interactions with antagonists. The findings reported here are in agreement with available experimental mutagenesis data. This study should be very helpful for a better understanding of the action mode of the antagonist and for guiding further drug design and mutagenesis studies. PMID:22779803

  8. Alpha adrenergic drugs inhibit ( sup 3 H)-QNB binding to muscarinic receptors of rat heart, brain and parotid gland membranes

    SciTech Connect

    Simon, G.; Filep, J.; Zelles, T. )

    1990-01-01

    Alpha adrenergic agonists and antagonists as clonidine, guanfacine, yohimbine, phenylephrine and prazosin inhibited the ({sup 3}H)-QNB binding to rat brain cortex muscarinic acetylcholine receptor (mAChR, M-1 subtype), heart (M-2 subtype) and parotid gland homogenate (M-3 subtype) in a dose-dependent competitive fashion. Ki values were between 10{sup {minus}6} and 10{sup {minus}3} M. Hill coefficients were about 1. No correlation was found between mAChR inhibiting capacity of these drugs and their activity on alpha adrenergic receptors. In contrast, other transmitters, as dopamine, GABA, glutamic acid, histamine, serotonin, isoproterenol and platelet activating factor (PAF) did not affect the QNB binding.

  9. Higenamine 4'-O-β-d-glucoside in the lotus plumule induces glucose uptake of L6 cells through β2-adrenergic receptor.

    PubMed

    Kato, Eisuke; Inagaki, Yosuke; Kawabata, Jun

    2015-07-01

    Hypoglycemic effect is an efficient means to modulate elevated blood glucose levels in patients with diabetes. We found that the extract of lotus plumule (the germ of Nelumbo nucifera Gaertn. seed) showed potent glucose uptake enhancement activity against L6 myotubes, which results in a hypoglycemic effect. This activity was further investigated, and an active constituent was identified as a single bioactive compound, higenamine 4'-O-β-d-glucoside. Mechanistic studies employing phosphatidylinositol 3-kinase (PI3K) inhibitor, AMP-activated protein kinase (AMPK) inhibitor, or adrenergic receptor antagonist showed that the compound induced its activity through β2-adrenergic receptor. Patients with type II diabetes mellitus frequently develop insulin resistance. Owing to the differences between the mechanism of action of insulin and of the isolated compound, the compound or lotus plumule itself may have the possibility of modulating blood glucose levels in insulin-resistant patients effectively. PMID:25943853

  10. β-Adrenergic receptor signaling and modulation of long-term potentiation in the mammalian hippocampus

    PubMed Central

    O'Dell, Thomas J.; Connor, Steven A.; Guglietta, Ryan

    2015-01-01

    Encoding new information in the brain requires changes in synaptic strength. Neuromodulatory transmitters can facilitate synaptic plasticity by modifying the actions and expression of specific signaling cascades, transmitter receptors and their associated signaling complexes, genes, and effector proteins. One critical neuromodulator in the mammalian brain is norepinephrine (NE), which regulates multiple brain functions such as attention, perception, arousal, sleep, learning, and memory. The mammalian hippocampus receives noradrenergic innervation and hippocampal neurons express β-adrenergic receptors, which are known to play important roles in gating the induction of long-lasting forms of synaptic potentiation. These forms of long-term potentiation (LTP) are believed to importantly contribute to long-term storage of spatial and contextual memories in the brain. In this review, we highlight the contributions of noradrenergic signaling in general and β-adrenergic receptors in particular, toward modulating hippocampal LTP. We focus on the roles of NE and β-adrenergic receptors in altering the efficacies of specific signaling molecules such as NMDA and AMPA receptors, protein phosphatases, and translation initiation factors. Also, the roles of β-adrenergic receptors in regulating synaptic “tagging” and “capture” of LTP within synaptic networks of the hippocampus are reviewed. Understanding the molecular and cellular bases of noradrenergic signaling will enrich our grasp of how the brain makes new, enduring memories, and may shed light on credible strategies for improving mental health through treatment of specific disorders linked to perturbed memory processing and dysfunctional noradrenergic synaptic transmission. PMID:26286656

  11. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists

    PubMed Central

    Khanfar, Mohammad A.; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures. PMID:27303254

  12. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists.

    PubMed

    Khanfar, Mohammad A; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures. PMID:27303254

  13. α1B-adrenergic receptors differentially associate with Rab proteins during homologous and heterologous desensitization.

    PubMed

    Castillo-Badillo, Jean A; Sánchez-Reyes, Omar B; Alfonzo-Méndez, Marco A; Romero-Ávila, M Teresa; Reyes-Cruz, Guadalupe; García-Sáinz, J Adolfo

    2015-01-01

    Internalization of G protein-coupled receptors can be triggered by agonists or by other stimuli. The process begins within seconds of cell activation and contributes to receptor desensitization. The Rab GTPase family controls endocytosis, vesicular trafficking, and endosomal fusion. Among their remarkable properties is the differential distribution of its members on the surface of various organelles. In the endocytic pathway, Rab 5 controls traffic from the plasma membrane to early endosomes, whereas Rab 4 and Rab 11 regulate rapid and slow recycling from early endosomes to the plasma membrane, respectively. Moreover, Rab 7 and Rab 9 regulate the traffic from late endosomes to lysosomes and recycling to the trans-Golgi. We explore the possibility that α1B-adrenergic receptor internalization induced by agonists (homologous) and by unrelated stimuli (heterologous) could involve different Rab proteins. This possibility was explored by Fluorescence Resonance Energy Transfer (FRET) using cells coexpressing α1B-adrenergic receptors tagged with the red fluorescent protein, DsRed, and different Rab proteins tagged with the green fluorescent protein. It was observed that when α1B-adrenergic receptors were stimulated with noradrenaline, the receptors interacted with proteins present in early endosomes, such as the early endosomes antigen 1, Rab 5, Rab 4, and Rab 11 but not with late endosome markers, such as Rab 9 and Rab 7. In contrast, sphingosine 1-phosphate stimulation induced rapid and transient α1B-adrenergic receptor interaction of relatively small magnitude with Rab 5 and a more pronounced and sustained one with Rab 9; interaction was also observed with Rab 7. Moreover, the GTPase activity of the Rab proteins appears to be required because no FRET was observed when dominant-negative Rab mutants were employed. These data indicate that α1B-adrenergic receptors are directed to different endocytic vesicles depending on the desensitization type (homologous vs

  14. α1B-Adrenergic Receptors Differentially Associate with Rab Proteins during Homologous and Heterologous Desensitization

    PubMed Central

    Castillo-Badillo, Jean A.; Sánchez-Reyes, Omar B.; Alfonzo-Méndez, Marco A.; Romero-Ávila, M. Teresa; Reyes-Cruz, Guadalupe; García-Sáinz, J. Adolfo

    2015-01-01

    Internalization of G protein-coupled receptors can be triggered by agonists or by other stimuli. The process begins within seconds of cell activation and contributes to receptor desensitization. The Rab GTPase family controls endocytosis, vesicular trafficking, and endosomal fusion. Among their remarkable properties is the differential distribution of its members on the surface of various organelles. In the endocytic pathway, Rab 5 controls traffic from the plasma membrane to early endosomes, whereas Rab 4 and Rab 11 regulate rapid and slow recycling from early endosomes to the plasma membrane, respectively. Moreover, Rab 7 and Rab 9 regulate the traffic from late endosomes to lysosomes and recycling to the trans-Golgi. We explore the possibility that α1B-adrenergic receptor internalization induced by agonists (homologous) and by unrelated stimuli (heterologous) could involve different Rab proteins. This possibility was explored by Fluorescence Resonance Energy Transfer (FRET) using cells coexpressing α1B-adrenergic receptors tagged with the red fluorescent protein, DsRed, and different Rab proteins tagged with the green fluorescent protein. It was observed that when α1B-adrenergic receptors were stimulated with noradrenaline, the receptors interacted with proteins present in early endosomes, such as the early endosomes antigen 1, Rab 5, Rab 4, and Rab 11 but not with late endosome markers, such as Rab 9 and Rab 7. In contrast, sphingosine 1-phosphate stimulation induced rapid and transient α1B-adrenergic receptor interaction of relatively small magnitude with Rab 5 and a more pronounced and sustained one with Rab 9; interaction was also observed with Rab 7. Moreover, the GTPase activity of the Rab proteins appears to be required because no FRET was observed when dominant-negative Rab mutants were employed. These data indicate that α1B-adrenergic receptors are directed to different endocytic vesicles depending on the desensitization type (homologous vs

  15. Transfer of SAR information from hypotensive indazole to indole derivatives acting at α-adrenergic receptors: In vitro and in vivo studies.

    PubMed

    Sączewski, Jaroslaw; Hudson, Alan; Scheinin, Mika; Wasilewska, Aleksandra; Sączewski, Franciszek; Rybczyńska, Apolonia; Ferdousi, Mehnaz; Laurila, Jonne M; Boblewski, Konrad; Lehmann, Artur; Watts, Helena; Ma, Daqing

    2016-06-10

    In a search for novel antihypertensive drugs we applied scaffold hopping from the previously described α1-adrenergic receptor antagonists, 1-[(imidazolin-2-yl)methyl]indazoles. The aim was to investigate whether the α-adrenergic properties of the indazole core were transferable to the indole core. The newly obtained 1-[(imidazolin-2-yl)methyl]indole analogues were screened in vitro for their binding affinities for α1-and α2-adrenoceptors, which allowed the identification of the target-based SAR transfer (T_SAR transfer) as well as structure-based SAR transfer (S_SAR transfer) events. However, when screened in vivo with use of anaesthetized male Wistar rats, the new indole ligands showed a different hemodynamic profile than expected. Instead of the immediate hypotensive effect characteristic of peripheral vasodilatator α1 blockers, a biphasic effect was observed, reminiscent of clonidine-like centrally acting antihypertensive agents. This was supported by subsequent in vitro functional studies in [(35)S]GTPγS binding assay, where the indole analogues displayed partial agonist properties at α2-adrenergic receptors. Since no correlation was found between the in vitro binding to α-adrenoceptors and the in vivo hemodynamic effects of the two series of indazole and indole bioisosteric compounds, in a search for new imidazoline-containing adrenergic drugs, the structure-based SAR transfer information obtained from in vitro binding studies should be treated with caution. PMID:27031216

  16. Indole-like Trk receptor antagonists.

    PubMed

    Tammiku-Taul, Jaana; Park, Rahel; Jaanson, Kaur; Luberg, Kristi; Dobchev, Dimitar A; Kananovich, Dzmitry; Noole, Artur; Mandel, Merle; Kaasik, Allen; Lopp, Margus; Timmusk, Tõnis; Karelson, Mati

    2016-10-01

    The virtual screening for new scaffolds for TrkA receptor antagonists resulted in potential low molecular weight drug candidates for the treatment of neuropathic pain and cancer. In particular, the compound (Z)-3-((5-methoxy-1H-indol-3-yl)methylene)-2-oxindole and its derivatives were assessed for their inhibitory activity against Trk receptors. The IC50 values were computationally predicted in combination of molecular and fragment-based QSAR. Thereafter, based on the structure-activity relationships (SAR), a series of new compounds were designed and synthesized. Among the final selection of 13 compounds, (Z)-3-((5-methoxy-1-methyl-1H-indol-3-yl)methylene)-N-methyl-2-oxindole-5-sulfonamide showed the best TrkA inhibitory activity using both biochemical and cellular assays and (Z)-3-((5-methoxy-1-methyl-1H-indol-3-yl)methylene)-2-oxindole-5-sulfonamide was the most potent inhibitor of TrkB and TrkC. PMID:27318978

  17. Real-time optical recording of beta1-adrenergic receptor activation reveals supersensitivity of the Arg389 variant to carvedilol.

    PubMed

    Rochais, Francesca; Vilardaga, Jean-Pierre; Nikolaev, Viacheslav O; Bünemann, Moritz; Lohse, Martin J; Engelhardt, Stefan

    2007-01-01

    Antagonists of beta-adrenergic receptors (beta-ARs) have become a main therapeutic regimen for the treatment of heart failure even though the mechanisms of their beneficial effects are still poorly understood. Here, we used fluorescent resonance energy transfer-based (FRET-based) approaches to directly monitor activation of the beta(1)-AR and downstream signaling. While the commonly used beta-AR antagonists metoprolol, bisoprolol, and carvedilol displayed varying degrees of inverse agonism on the Gly389 variant of the receptor (i.e., actively switching off the beta(1)-AR), surprisingly, only carvedilol showed very specific and marked inverse agonist effects on the more frequent Arg389 variant. These specific effects of carvedilol on the Arg389 variant of the beta(1)-AR were also seen for control of beating frequency in rat cardiac myocytes expressing the 2 receptor variants. This FRET sensor permitted direct observation of activation of the beta(1)-AR in living cells in real time. It revealed that beta(1)-AR variants dramatically differ in their responses to diverse beta blockers, with possible consequences for their clinical use. PMID:17200720

  18. Analysis of functional selectivity through G protein-dependent and -independent signaling pathways at the adrenergic α(2C) receptor.

    PubMed

    Kurko, Dalma; Kapui, Zoltán; Nagy, József; Lendvai, Balázs; Kolok, Sándor

    2014-08-01

    Although G protein-coupled receptors (GPCRs) are traditionally categorized as Gs-, Gq-, or Gi/o-coupled, their signaling is regulated by multiple mechanisms. GPCRs can couple to several effector pathways, having the capacity to interact not only with more than one G protein subtype but also with alternative signaling or effector proteins such as arrestins. Moreover, GPCR ligands can have different efficacies for activating these signaling pathways, a characteristic referred to as biased agonism or functional selectivity. In this work our aim was to detect differences in the ability of various agonists acting at the α2C type of adrenergic receptors (α2C-ARs) to modulate cAMP accumulation, cytoplasmic Ca(2+) release, β-arrestin recruitment and receptor internalization. A detailed comparative pharmacological characterization of G protein-dependent and -independent signaling pathways was carried out using adrenergic agonists (norepinephrine, phenylephrine, brimonidine, BHT-920, oxymetazoline, clonidine, moxonidine, guanabenz) and antagonists (MK912, yohimbine). As initial analysis of agonist Emax and EC50 values suggested possible functional selectivity, ligand bias was quantified by applying the relative activity scale and was compared to that of the endogenous agonist norepinephrine. Values significantly different from 0 between pathways indicated an agonist that promoted different level of activation of diverse effector pathways most likely due to the stabilization of a subtly different receptor conformation from that induced by norepinephrine. Our results showed that a series of agonists acting at the α2C-AR displayed different degree of functional selectivity (bias factors ranging from 1.6 to 36.7) through four signaling pathways. As signaling via these pathways seems to have distinct functional and physiological outcomes, studying all these stages of receptor activation could have further implications for the development of more selective therapeutics with

  19. beta-Adrenergic and cholinergic receptors in hypertension-induced hypertrophy

    SciTech Connect

    Vatner, D.E.; Kirby, D.A.; Homcy, C.J.; Vatner, S.F.

    1985-05-01

    Perinephritic hypertension was produced in dogs by wrapping one kidney with silk and removing the contralateral kidney 1 week later. Mean arterial pressure rose from 104 +/- 3 to 156 +/- 11 mm Hg, while left ventricular free wall weight, normalized for body weight, was increased by 49%. Muscarinic, cholinergic receptor density measured with (/sup 3/H)-quinuclidinyl benzilate, fell in hypertensive left ventricles (181 +/- 19 fmol/mg, n = 6; p less than 0.01) as compared with that found in normal left ventricles (272 +/- 16 fmol/mg, n = 8), while receptor affinity was not changed. The beta-adrenergic receptor density, measured by binding studies with (/sup 3/H)-dihydroalprenolol, rose in the hypertensive left ventricles (108 +/- 10 fmol/mg, n = 7; p less than 0.01) as compared with that found in normal left ventricles (68.6 +/- 5.2 fmol/mg, n = 15), while beta-adrenergic receptor affinity decreased in the hypertensive left ventricles (10.4 +/- 1.2 nM) compared with that found in the normal left ventricles (5.0 +/- 0.7 nM). Plasma norepinephrine levels were similar in the two groups, but myocardial norepinephrine levels were depressed (p less than 0.05) in dogs with hypertension. Moderate left ventricular hypertrophy induced by long-term aortic banding in dogs resulted in elevations in beta-adrenergic receptor density (115 +/- 14 fmol/mg) and decreases in affinity (10.4 +/- 2.2 nM) similar to those observed in the dogs with left ventricular hypertrophy induced by hypertension. Thus, these results suggest that perinephritic hypertension in the dog induces divergent effects on cholinergic and beta-adrenergic receptor density. The increased beta-adrenergic receptor density and decreased affinity may be a characteristic of left ventricular hypertrophy rather than hypertension.

  20. Sympathetic neural signaling via the β2-adrenergic receptor suppresses T-cell receptor-mediated human and mouse CD8(+) T-cell effector function.

    PubMed

    Estrada, Leonardo D; Ağaç, Didem; Farrar, J David

    2016-08-01

    Postganglionic sympathetic neurons innervate secondary lymphoid organs and secrete norepinephrine (NE) as the primary neurotransmitter. NE binds and signals through five distinct members of the adrenergic receptor family. In this study, we show elevated expression of the β2-adrenergic receptor (ADRB2) on primary human CD8(+) effector memory T cells. Treatment of both human and murine CD8(+) T cells with NE decreased IFN-γ and TNF-α secretion and suppressed their cytolytic capacity in response to T-cell receptor (TCR) activation. The effects of NE were specifically reversed by β2-specific antagonists. Adrb2(-/-) CD8(+) T cells were completely resistant to the effects of NE. Further, the ADRB2-specific pharmacological ligand, albuterol, significantly suppressed effector functions in both human and mouse CD8(+) T cells. While both TCR activation and stimulation with IL-12 + IL-18 were able to induce inflammatory cytokine secretion, NE failed to suppress IFN-γ secretion in response to IL-12 + IL18. Finally, the long-acting ADRB2-specific agonist, salmeterol, markedly reduced the cytokine secretion capacity of CD8(+) T cells in response to infection with vesicular stomatitis virus. This study reveals a novel intrinsic role for ADRB2 signaling in CD8(+) T-cell function and underscores the novel role this pathway plays in adaptive T-cell responses to infection. PMID:27222010

  1. Pharmacological Analysis and Structure Determination of 7-Methylcyanopindolol–Bound β1-Adrenergic Receptor

    PubMed Central

    Sato, Tomomi; Baker, Jillian; Warne, Tony; Brown, Giles A.; Leslie, Andrew G.W.; Congreve, Miles

    2015-01-01

    Comparisons between structures of the β1-adrenergic receptor (AR) bound to either agonists, partial agonists, or weak partial agonists led to the proposal that rotamer changes of Ser5.46, coupled to a contraction of the binding pocket, are sufficient to increase the probability of receptor activation. (RS)-4-[3-(tert-butylamino)-2-hydroxypropoxy]-1H-indole-2-carbonitrile (cyanopindolol) is a weak partial agonist of β1AR and, based on the hypothesis above, we predicted that the addition of a methyl group to form 4-[(2S)-3-(tert-butylamino)-2-hydroxypropoxy]-7-methyl-1H-indole-2-carbonitrile (7-methylcyanopindolol) would dramatically reduce its efficacy. An eight-step synthesis of 7-methylcyanopindolol was developed and its pharmacology was analyzed. 7-Methylcyanopindolol bound with similar affinity to cyanopindolol to both β1AR and β2AR. As predicted, the efficacy of 7-methylcyanopindolol was reduced significantly compared with cyanopindolol, acting as a very weak partial agonist of turkey β1AR and an inverse agonist of human β2AR. The structure of 7-methylcyanopindolol–bound β1AR was determined to 2.4-Å resolution and found to be virtually identical to the structure of cyanopindolol-bound β1AR. The major differences in the orthosteric binding pocket are that it has expanded by 0.3 Å in 7-methylcyanopindolol–bound β1AR and the hydroxyl group of Ser5.46 is positioned 0.8 Å further from the ligand, with respect to the position of the Ser5.46 side chain in cyanopindolol-bound β1AR. Thus, the molecular basis for the reduction in efficacy of 7-methylcyanopindolol compared with cyanopindolol may be regarded as the opposite of the mechanism proposed for the increase in efficacy of agonists compared with antagonists. PMID:26385885

  2. Pharmacological Analysis and Structure Determination of 7-Methylcyanopindolol-Bound β1-Adrenergic Receptor.

    PubMed

    Sato, Tomomi; Baker, Jillian; Warne, Tony; Brown, Giles A; Leslie, Andrew G W; Congreve, Miles; Tate, Christopher G

    2015-12-01

    Comparisons between structures of the β1-adrenergic receptor (AR) bound to either agonists, partial agonists, or weak partial agonists led to the proposal that rotamer changes of Ser(5.46), coupled to a contraction of the binding pocket, are sufficient to increase the probability of receptor activation. (RS)-4-[3-(tert-butylamino)-2-hydroxypropoxy]-1H-indole-2-carbonitrile (cyanopindolol) is a weak partial agonist of β1AR and, based on the hypothesis above, we predicted that the addition of a methyl group to form 4-[(2S)-3-(tert-butylamino)-2-hydroxypropoxy]-7-methyl-1H-indole-2-carbonitrile (7-methylcyanopindolol) would dramatically reduce its efficacy. An eight-step synthesis of 7-methylcyanopindolol was developed and its pharmacology was analyzed. 7-Methylcyanopindolol bound with similar affinity to cyanopindolol to both β1AR and β2AR. As predicted, the efficacy of 7-methylcyanopindolol was reduced significantly compared with cyanopindolol, acting as a very weak partial agonist of turkey β1AR and an inverse agonist of human β2AR. The structure of 7-methylcyanopindolol-bound β1AR was determined to 2.4-Å resolution and found to be virtually identical to the structure of cyanopindolol-bound β1AR. The major differences in the orthosteric binding pocket are that it has expanded by 0.3 Å in 7-methylcyanopindolol-bound β1AR and the hydroxyl group of Ser(5.46) is positioned 0.8 Å further from the ligand, with respect to the position of the Ser(5.46) side chain in cyanopindolol-bound β1AR. Thus, the molecular basis for the reduction in efficacy of 7-methylcyanopindolol compared with cyanopindolol may be regarded as the opposite of the mechanism proposed for the increase in efficacy of agonists compared with antagonists. PMID:26385885

  3. Robust experiment design for estimating myocardial {beta} adrenergic receptor concentration using PET

    SciTech Connect

    Salinas, Cristian; Muzic, Raymond F. Jr.; Ernsberger, Paul; Saidel, Gerald M.

    2007-01-15

    Myocardial {beta} adrenergic receptor ({beta}-AR) concentration can substantially decrease in congestive heart failure and significantly increase in chronic volume overload, such as in severe aortic valve regurgitation. Positron emission tomography (PET) with an appropriate ligand-receptor model can be used for noninvasive estimation of myocardial {beta}-AR concentration in vivo. An optimal design of the experiment protocol, however, is needed for sufficiently precise estimates of {beta}-AR concentration in a heterogeneous population. Standard methods of optimal design do not account for a heterogeneous population with a wide range of {beta}-AR concentrations and other physiological parameters and consequently are inadequate. To address this, we have developed a methodology to design a robust two-injection protocol that provides reliable estimates of myocardial {beta}-AR concentration in normal and pathologic states. A two-injection protocol of the high affinity {beta}-AR antagonist [{sup 18}F]-(S)-fluorocarazolol was designed based on a computer-generated (or synthetic) population incorporating a wide range of {beta}-AR concentrations. Timing and dosage of the ligand injections were optimally designed with minimax criterion to provide the least bad {beta}-AR estimates for the worst case in the synthetic population. This robust experiment design for PET was applied to experiments with pigs before and after {beta}-AR upregulation by chemical sympathectomy. Estimates of {beta}-AR concentration were found by minimizing the difference between the model-predicted and experimental PET data. With this robust protocol, estimates of {beta}-AR concentration showed high precision in both normal and pathologic states. The increase in {beta}-AR concentration after sympathectomy predicted noninvasively with PET is consistent with the increase shown by in vitro assays in pig myocardium. A robust experiment protocol was designed for PET that yields reliable estimates of {beta

  4. The avian beta-adrenergic receptor: primary structure and membrane topology.

    PubMed Central

    Yarden, Y; Rodriguez, H; Wong, S K; Brandt, D R; May, D C; Burnier, J; Harkins, R N; Chen, E Y; Ramachandran, J; Ullrich, A

    1986-01-01

    Partial amino acid sequence information allowed the isolation of cDNA clones encoding the turkey erythrocyte beta-adrenergic receptor. Antisera raised against synthetic peptides encoded by the cDNA crossreacted with the purified receptor and appropriate tryptic fragments, confirming the identity of the cDNA. The receptor is composed of 483 amino acids and has a molecular mass of 54 kDa. Its sequence suggests that it is arranged predominantly in seven membrane-spanning sequences and a long cytoplasmic carboxyl-terminal domain. The extracellular amino-terminal domain contains a consensus sequence for N-glycosylation. The beta-adrenergic receptor displays overall structural similarity and weak sequence homology with rhodopsin. Because both proteins act by regulating GTP-binding proteins, a compact structure based on seven membrane-spanning regions may be a general model for receptors that act on G proteins. Images PMID:3018746

  5. Comparative biochemical and pharmacological characterization of the mouse 5HT5A 5-hydroxytryptamine receptor and the human beta2-adrenergic receptor produced in the methylotrophic yeast Pichia pastoris.

    PubMed

    Weiss, H M; Haase, W; Michel, H; Reiländer, H

    1998-03-15

    Over the last few years, Pichia pastoris has been developed into a powerful expression system for a multitude of foreign genes. Here, we demonstrate that the P. pastoris expression system has similar power to the baculovirus expression system in high-level production of two G-protein-coupled receptors, the mouse 5HT5A 5-hydroxtryptamine receptor and the human beta2-adrenergic receptor. Different expression plasmids were constructed in which the cDNAs of the two receptors were cloned under the transcriptional control of the highly inducible promoter of the P. pastoris alcohol oxidase 1 (AOX1) gene. In three expression plasmids, the receptors were fused to the Saccharomyces cerevisiae alpha-factor prepropeptide and also to the c-myc tag or the FLAG tag to permit immunological detection of the receptors. After transformation into P. pastoris strains KM71 and SMD 1163, recombinant clones were selected and tested for the production of the 5HT5A receptor and the beta2-adrenergic receptor by radioligand binding using [N-methyl-3H]lysergic acid diethylamide and [5,7-3H](-)CGP-12177 respectively. The production level of the 5HT5A receptor was improved by a factor of three by fusion with the alpha-factor prepropeptide. Also, the higher gene dosage resulting from multiple insertions of the expression cassette led to an improvement in production by a factor of two for both receptors. The addition of the adrenergic antagonist alprenolol to the culture medium had a positive effect on the number of specific binding sites detectable in clones producing the beta2-adrenergic receptor. For the 5HT5A receptor the addition of yohimbine resulted in a similar but smaller effect. Binding assays revealed that approx. 25 pmol of beta2-adrenergic receptor and approx. 40 pmol of 5HT5A receptor per mg of membrane protein in crude membrane preparations were produced. The pharmacological profiles for the heterologously produced receptors, estimated by ligand-displacement analysis using certain

  6. β2 Adrenergic receptors mediate important electrophysiological effects in human ventricular myocardium

    PubMed Central

    Lowe, M; Rowland, E; Brown, M; Grace, A

    2001-01-01

    OBJECTIVE—To define the effects of β2 adrenergic receptor stimulation on ventricular repolarisation in vivo.
DESIGN—Prospective study.
SETTING—Tertiary referral centre.
PATIENTS—85 patients with coronary artery disease and 22 normal controls.
INTERVENTIONS—Intravenous and intracoronary salbutamol (a β2 adrenergic receptor selective agonist; 10-30 µg/min and 1-10 µg/min), and intravenous isoprenaline (a mixed β1/β2 adrenergic receptor agonist; 1-5 µg/min), infused during fixed atrial pacing.
MAIN OUTCOME MEASURES—QT intervals, QT dispersion, monophasic action potential duration.
RESULTS—In patients with coronary artery disease, salbutamol decreased QTonset and QTpeak but increased QTend duration; QTonset-QTpeak and QTpeak-QTend intervals increased, resulting in T wave prolongation (mean (SEM): 201 (2) ms to 233 (2) ms; p < 0.01). There was a large increase in dispersion of QTonset, QTpeak, and QTend which was more pronounced in patients with coronary artery disease—for example, QTend dispersion: 50 (2) ms baseline v 98 (4) ms salbutamol (controls), and 70 (1) ms baseline v 108 (3) ms salbutamol (coronary artery disease); p < 0.001. Similar responses were obtained with isoprenaline. Monophasic action potential duration at 90% repolarisation shortened during intracoronary infusion of salbutamol, from 278 (4.1) ms to 257 (3.8) ms (p < 0.05).
CONCLUSIONS—β2 adrenergic receptors mediate important electrophysiological effects in human ventricular myocardium. The increase in dispersion of repolarisation provides a mechanism whereby catecholamines acting through this receptor subtype may trigger ventricular arrhythmias.


Keywords: β2 adrenergic receptors; ventricular repolarisation; QT dispersion; salbutamol; isoprenaline PMID:11410561

  7. BLOCKAGE OF A-1 ADRENERGIC RECEPTOR INHIBOTS HEPATIC DNA SYNTHESIS STIMULATED BY TUMOR PROMOTERS

    EPA Science Inventory

    Studies with regenerating liver and hepatocyte cultures have shown that the a-1 adrenergic receptor (A1AR) is involved in the early events which transmit a mitogenic signal to hepatocytes after 2/3 partial hepatectomy. n this study, we investigated the role of A1AR in DNA synthes...

  8. The functional role of the alpha-1 adrenergic receptors in cerebral blood flow regulation

    PubMed Central

    Purkayastha, Sushmita; Raven, Peter B.

    2011-01-01

    Cerebral vasculature is richly innervated by the α-1 adrenergic receptors similar to that of the peripheral vasculature. However, the functional role of the α-1adrenergic receptors in cerebral blood flow (CBF) regulation is yet to be established. The traditional thinking being that during normotension and normocapnia sympathetic neural activity does not play a significant role in CBF regulation. Reports in the past have stated that catecholamines do not penetrate the blood brain barrier (BBB) and therefore only influence cerebral vessels from outside the BBB and hence, have a limited role in CBF regulation. However, with the advent of dynamic measurement techniques, beat-to-beat CBF assessment can be done during dynamic changes in arterial blood pressure. Several studies in the recent years have reported a functional role of the α-1adrenergic receptors in CBF regulation. This review focuses on the recent developments on the role of the sympathetic nervous system, specifically that of the α-1 adrenergic receptors in CBF regulation. PMID:22021989

  9. Endothelin receptor antagonists in the treatment of pulmonary arterial hypertension.

    PubMed

    Langleben, David

    2007-03-01

    The recognition that endothelin-1 contributes to the pathogenesis of pulmonary arterial hypertension has led to the development of clinically useful endothelin receptor antagonists that improve symptoms and functional capacity and alter the natural history of the disease in a beneficial way. The antagonists have varying degrees of selectivity for the two classes of endothelin receptor, termed ETA and ETB, and the varying degrees may translate into clinical differences. Endothelin receptor antagonists have become an integral part of therapy for pulmonary arterial hypertension, and the indications for their use are expanding. PMID:17338931

  10. Propranolol, a β-adrenergic antagonist, attenuates the decrease in trabecular bone mass in high calorie diet fed growing mice.

    PubMed

    Baek, Kyunghwa; Hwang, Hyo Rin; Park, Hyun-Jung; Kwon, Arang; Qadir, Abdul S; Baek, Jeong-Hwa

    2014-09-01

    We investigated the effects of high calorie and low calorie diets on skeletal integrity, and whether β-adrenergic blockade (BB) attenuates bone loss induced by dietary calorie alteration. Male 6-week-old C57BL/6 mice were assigned to either an ad-lib fed control diet (CON), a high calorie diet (HIGH), or a low calorie diet (LOW) group. In each diet group, mice were treated with either vehicle (VEH) or propranolol, a β-adrenergic antagonist. Over 12-weeks, β-blockade mitigated body weight and fat mass increases induced by the high calorie diet. Femoral trabecular bone mineral density and the expression levels of osteogenic marker genes in bone marrow cells were reduced in HIGHVEH and LOWVEH mice, and BB significantly attenuated this decline only in HIGH mice. In summary, the magnitude of bone loss induced by low calorie diet was greater than that caused by high calorie diet in growing mice, and β-blockade mitigated high calorie diet-induced bone loss. PMID:24393528

  11. Propranolol, a β-adrenergic antagonist, attenuates the decrease in trabecular bone mass in high calorie diet fed growing mice

    PubMed Central

    Baek, Kyunghwa; Hwang, Hyo Rin; Park, Hyun-Jung; Kwon, Arang; Qadir, Abdul S.; Baek, Jeong-Hwa

    2014-01-01

    We investigated the effects of high calorie and low calorie diets on skeletal integrity, and whether β-adrenergic blockade (BB) attenuates bone loss induced by dietary calorie alteration. Male 6-week-old C57BL/6 mice were assigned to either an ad-lib fed control diet (CON), a high calorie diet (HIGH), or a low calorie diet (LOW) group. In each diet group, mice were treated with either vehicle (VEH) or propranolol, a β-adrenergic antagonist. Over 12-weeks, β-blockade mitigated body weight and fat mass increases induced by the high calorie diet. Femoral trabecular bone mineral density and the expression levels of osteogenic marker genes in bone marrow cells were reduced in HIGHVEH and LOWVEH mice, and BB significantly attenuated this decline only in HIGH mice. In summary, the magnitude of bone loss induced by low calorie diet was greater than that caused by high calorie diet in growing mice, and β-blockade mitigated high calorie diet-induced bone loss. [BMB Reports 2014; 47(9): 506-511] PMID:24393528

  12. Localized β-adrenergic receptor blockade does not affect sweating during exercise.

    PubMed

    Buono, Michael J; Tabor, Brian; White, Ailish

    2011-05-01

    The purpose of the current study was to determine the effect of a locally administered nonselective β-adrenergic antagonist on sweat gland function during exercise. Systemically administered propranolol has been reported to increase, decrease, or not alter sweat production during exercise. To eliminate the confounding systemic effects associated with orally administered propranolol, we used iontophoresis to deliver it to the eccrine sweat glands within a localized area on one forearm prior to exercise. This allowed for determination of the direct effect of β-adrenergic receptor blockade on sweating during exercise. Subjects (n = 14) reported to the laboratory (23 ± 1°C, 35 ± 3% relative humidity) after having refrained from exercise for ≥12 h. Propranolol (1% solution) was administered to a 5-cm(2) area of the flexor surface of one forearm via iontophoresis (1.5 mA) for 5 min. A saline solution was administered to the opposing arm via iontophoresis. Each subject then exercised on a motor-driven treadmill at 75% of their age-predicted maximal heart rate for 20 min, while sweat rate was measured simultaneously in both forearms. Immediately after cessation of exercise, the number of active sweat glands was measured by application of iodine-impregnated paper to each forearm. The sweat rate for the control and propranolol-treated forearm was 0.62 ± 41 and 0.60 ± 0.44 (SD) mg·cm(-2)·min(-1), respectively (P = 0.86). The density of active sweat glands for the control and propranolol-treated forearm was 130 ± 6 and 134 ± 5 (SD) glands/cm(2), respectively, (P = 0.33). End-exercise skin temperature was 32.9 ± 0.2 and 33.1 ± 0.3°C for the control and propranolol-treated forearm, respectively (P = 0.51). Results of the current study show that when propranolol is administered locally, thus eliminating the potential confounding systemic effects of the drug, it does not directly affect sweating during the initial stages of high-intensity exercise in young, healthy

  13. Cholesterol Modulates the Dimer Interface of the β2-Adrenergic Receptor via Cholesterol Occupancy Sites

    PubMed Central

    Prasanna, Xavier; Chattopadhyay, Amitabha; Sengupta, Durba

    2014-01-01

    The β2-adrenergic receptor is an important member of the G-protein-coupled receptor (GPCR) superfamily, whose stability and function are modulated by membrane cholesterol. The recent high-resolution crystal structure of the β2-adrenergic receptor revealed the presence of possible cholesterol-binding sites in the receptor. However, the functional relevance of cholesterol binding to the receptor remains unexplored. We used MARTINI coarse-grained molecular-dynamics simulations to explore dimerization of the β2-adrenergic receptor in lipid bilayers containing cholesterol. A novel (to our knowledge) aspect of our results is that receptor dimerization is modulated by membrane cholesterol. We show that cholesterol binds to transmembrane helix IV, and cholesterol occupancy at this site restricts its involvement at the dimer interface. With increasing cholesterol concentration, an increased presence of transmembrane helices I and II, but a reduced presence of transmembrane helix IV, is observed at the dimer interface. To our knowledge, this study is one of the first to explore the correlation between cholesterol occupancy and GPCR organization. Our results indicate that dimer plasticity is relevant not just as an organizational principle but also as a subtle regulatory principle for GPCR function. We believe these results constitute an important step toward designing better drugs for GPCR dimer targets. PMID:24655504

  14. Altered hepatic vasopressin and alpha 1-adrenergic receptors after chronic endotoxin infusion

    SciTech Connect

    Roth, B.L.; Spitzer, J.A.

    1987-05-01

    Sepsis and septic shock are complicated by a number of hemodynamic and metabolic aberrations. These include catecholamine refractoriness and altered glucose metabolism. Recently, a nonshock rat model of continuous endotoxin infusion via an implanted osmotic pump was developed that reproduces some of the metabolic and cardiovascular findings of human sepsis. By using this model, we have found a decreased number of hepatic plasma membrane alpha 1-adrenergic and (Arg8)vasopressin receptors in rats continuously infused with endotoxin. There was a significant decrease in (/sup 3/H)prazosin (35 +/- 7%) and (/sup 3/H) (Arg8)vasopressin (43 +/- 8%) receptors after 30 h of continuous endotoxin infusion with no change in affinity. The ability of norepinephrine to form the high-affinity complex with alpha 1-adrenergic receptors was not altered after chronic endotoxin infusion. The results are consistent with the concept that alterations in receptor number might underlie certain of the metabolic consequences of chronic sepsis.

  15. Functional differences between junctional and extrajunctional adrenergic receptor activation in mammalian ventricle

    PubMed Central

    Ajijola, Olujimi A.; Vaseghi, Marmar; Zhou, Wei; Yamakawa, Kentaro; Benharash, Peyman; Hadaya, Joseph; Lux, Robert L.; Mahajan, Aman

    2013-01-01

    Increased cardiac sympathetic activation worsens dispersion of repolarization and is proarrhythmic. The functional differences between intrinsic nerve stimulation and adrenergic receptor activation remain incompletely understood. This study was undertaken to determine the functional differences between efferent cardiac sympathetic nerve stimulation and direct adrenergic receptor activation in porcine ventricles. Female Yorkshire pigs (n = 13) underwent surgical exposure of the heart and stellate ganglia. A 56-electrode sock was placed over the ventricles to record epicardial electrograms. Animals underwent bilateral sympathetic stimulation (BSS) (n = 8) or norepinephrine (NE) administration (n = 5). Activation recovery intervals (ARIs) were measured at each electrode before and during BSS or NE. The degree of ARI shortening during BSS or NE administration was used as a measure of functional nerve or adrenergic receptor density. During BSS, ARI shortening was nonuniform across the epicardium (F value 9.62, P = 0.003), with ARI shortening greatest in the mid-basal lateral right ventricle and least in the midposterior left ventricle (LV) (mean normalized values: 0.9 ± 0.08 vs. 0.56 ± 0.08; P = 0.03). NE administration resulted in greater ARI shortening in the LV apex than basal segments [0.91 ± 0.04 vs. 0.63 ± 0.05 (averaged basal segments); P = 0.003]. Dispersion of ARIs increased in 50% and 60% of the subjects undergoing BSS and NE, respectively, but decreased in the others. There is nonuniform response to cardiac sympathetic activation of both porcine ventricles, which is not fully explained by adrenergic receptor density. Different pools of adrenergic receptors may mediate the cardiac electrophysiological effects of efferent sympathetic nerve activity and circulating catecholamines. PMID:23241324

  16. Prostanoid receptor antagonists: development strategies and therapeutic applications

    PubMed Central

    Jones, RL; Giembycz, MA; Woodward, DF

    2009-01-01

    Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP1, EP2 …) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP1, TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP2). While some antagonists are structurally related to the natural agonist, most recent compounds are ‘non-prostanoid’ (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD2 (acting on DP1 and DP2 receptors) and PGE2 (on EP1 and EP4 receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage. PMID:19624532

  17. β-Adrenergic Receptor-Dependent Alterations in Murine Cardiac Transcript Expression Are Differentially Regulated by Gefitinib In Vivo

    PubMed Central

    Talarico, Jennifer A.; Carter, Rhonda L.; Grisanti, Laurel A.; Yu, Justine E.; Repas, Ashley A.; Tilley, Douglas G.

    2014-01-01

    β-adrenergic receptor (βAR)-mediated transactivation of epidermal growth factor receptor (EGFR) has been shown to promote cardioprotection in a mouse model of heart failure and we recently showed that this mechanism leads to enhanced cell survival in part via regulation of apoptotic transcript expression in isolated primary rat neonatal cardiomyocytes. Thus, we hypothesized that this process could regulate cardiac transcript expression in vivo. To comprehensively assess cardiac transcript alterations in response to acute βAR-dependent EGFR transactivation, we performed whole transcriptome analysis of hearts from C57BL/6 mice given i.p. injections of the βAR agonist isoproterenol in the presence or absence of the EGFR antagonist gefitinib for 1 hour. Total cardiac RNA from each treatment group underwent transcriptome analysis, revealing a substantial number of transcripts regulated by each treatment. Gefitinib alone significantly altered the expression of 405 transcripts, while isoproterenol either alone or in conjunction with gefitinib significantly altered 493 and 698 distinct transcripts, respectively. Further statistical analysis was performed, confirming 473 transcripts whose regulation by isoproterenol were significantly altered by gefitinib (isoproterenol-induced up/downregulation antagonized/promoted by gefinitib), including several known to be involved in the regulation of numerous processes including cell death and survival. Thus, βAR-dependent regulation of cardiac transcript expression in vivo can be modulated by the EGFR antagonist gefitinib. PMID:24901703

  18. α1-adrenergic receptors positively regulate Toll-like receptor cytokine production from human monocytes and macrophages.

    PubMed

    Grisanti, Laurel A; Woster, Andrew P; Dahlman, Julie; Sauter, Edward R; Combs, Colin K; Porter, James E

    2011-08-01

    Catecholamines released from the sympathetic nervous system in response to stress or injury affect expression of inflammatory cytokines generated by immune cells. α(1)-Adrenergic receptors (ARs) are expressed on innate immune cell populations, but their subtype expression patterns and signaling characteristics are not well characterized. Primary human monocytes, a human monocytic cell line, and monocyte-derived macrophage cells were used to measure expression of the proinflammatory mediator interleukin (IL)-1β responding to lipopolysaccharide (LPS) in the presence or absence of α(1)-AR activation. Based on our previous findings, we hypothesized that α(1)-AR stimulation on innate immune cells positively regulates LPS-initiated IL-1β production. IL-1β production in response to LPS was synergistically higher for both monocytes and macrophages in the presence of the selective α(1)-AR agonist (R)-(-)-phenylephrine hydrochloride (PE). This synergistic IL-1β response could be blocked with a selective α(1)-AR antagonist as well as inhibitors of protein kinase C (PKC). Radioligand binding studies characterized a homogenous α(1B)-AR subtype population on monocytes, which changed to a heterogeneous receptor subtype expression pattern when differentiated to macrophages. Furthermore, increased p38 mitogen-activated protein kinase (MAPK) activation was observed only with concurrent PE and LPS stimulation, peaking after 120 and 30 min in monocytes and macrophages, respectively. Blocking the PKC/p38 MAPK signaling pathway in both innate immune cell types inhibited the synergistic IL-1β increase observed with concurrent PE and LPS treatments. This study characterizes α(1)-AR subtype expression on both human monocyte and macrophage cells and illustrates a mechanism by which increased IL-1β production can be modulated by α(1)-AR input. PMID:21571945

  19. Attention-deficit hyperactivity disorder and the adrenergic receptors alpha 1C and alpha 2C.

    PubMed

    Barr, C L; Wigg, K; Zai, G; Roberts, W; Malone, M; Schachar, R; Tannock, R; Kennedy, J L

    2001-05-01

    The adrenergic system has been hypothesized to be involved in the etiology of attention-deficit hyperactivity disorder (ADHD) based on pharmacological interventions and animal models. Noradrenergic neurons are implicated in the modulation of vigilance, improvement of visual attention, initiation of adaptive response, learning and memory. In this study we tested the genes for two adrenergic receptors, alpha 1C (ADRA1C) located on chromosome 8p11.2, and alpha 2C (ADRA2C) located on chromosome 4p16, as genetic susceptibility factors in ADHD. For the adrenergic receptor alpha 1C we used a C to T polymorphism that results in a change of Cys to Arg at codon 492 for the linkage study. For the adrenergic receptor alpha 2C gene we examined a dinucleotide repeat polymorphism located approximately 6 kb from the gene. We examined these polymorphisms in a sample of 103 families ascertained through an ADHD proband. Using the transmission disequilibrium test, we did not observe biased transmission of any of the alleles of these polymorphisms. We conclude that the alleles at the polymorphisms tested in these two genes are not linked to the ADHD phenotype in this sample of families. PMID:11326305

  20. Inhibition of Ebola and Marburg Virus Entry by G Protein-Coupled Receptor Antagonists

    PubMed Central

    Cheng, Han; Lear-Rooney, Calli M.; Johansen, Lisa; Varhegyi, Elizabeth; Chen, Zheng W.; Olinger, Gene G.

    2015-01-01

    ABSTRACT Filoviruses, consisting of Ebola virus (EBOV) and Marburg virus (MARV), are among the most lethal infectious threats to mankind. Infections by these viruses can cause severe hemorrhagic fevers in humans and nonhuman primates with high mortality rates. Since there is currently no vaccine or antiviral therapy approved for humans, there is an urgent need to develop prophylactic and therapeutic options for use during filoviral outbreaks and bioterrorist attacks. One of the ideal targets against filoviral infection and diseases is at the entry step, which is mediated by the filoviral glycoprotein (GP). In this report, we screened a chemical library of small molecules and identified numerous inhibitors, which are known G protein-coupled receptor (GPCR) antagonists targeting different GPCRs, including histamine receptors, 5-HT (serotonin) receptors, muscarinic acetylcholine receptor, and adrenergic receptor. These inhibitors can effectively block replication of both infectious EBOV and MARV, indicating a broad antiviral activity of the GPCR antagonists. The time-of-addition experiment and microscopic studies suggest that GPCR antagonists block filoviral entry at a step following the initial attachment but prior to viral/cell membrane fusion. These results strongly suggest that GPCRs play a critical role in filoviral entry and GPCR antagonists can be developed as an effective anti-EBOV/MARV therapy. IMPORTANCE Infection of Ebola virus and Marburg virus can cause severe illness in humans with a high mortality rate, and currently there is no FDA-approved vaccine or therapeutic treatment available. The 2013-2015 epidemic in West Africa underscores a lack of our understanding in the infection and pathogenesis of these viruses and the urgency of drug discovery and development. In this study, we have identified numerous inhibitors that are known G protein-coupled receptor (GPCR) antagonists targeting different GPCRs. These inhibitors can effectively block replication of

  1. Transformation of human ciliary epithelial cells by simian virus 40: induction of cell proliferation and retention of beta 2-adrenergic receptors.

    PubMed Central

    Coca-Prados, M; Wax, M B

    1986-01-01

    Ciliary epithelial cells derived from human eye were successfully propagated through many generations after transformation with simian virus 40. The cell clone 8-SVHCE was isolated and characterized by immunoprecipitation and pharmacological studies that demonstrated the presence of several functional properties observed in the parent cells of this tissue. Immunoprecipitation revealed the presence of large tumor (T) antigen, and Southern blot analysis showed the incorporation of viral DNA into high molecular weight ciliary epithelial cell DNA. The presence of beta-adrenergic receptors was demonstrated by direct binding of a radiolabeled antagonist, [125I]iodopindolol, to membrane preparations of 8-SVHCE cells (Kd = 41.8 pM and Bmax = 67.1 fmol/mg of protein). Competition experiments with [125I]iodopindolol and selective drugs suggested that the receptors are of the beta 2-adrenergic subtype. Studies of catecholamine-stimulated cellular cAMP production and of isoproterenol-dependent protein phosphorylation of vimentin in 8-SVHCE indicated the functional conservation of beta-adrenergic receptor-mediated processes that are thought to be important in the regulation of aqueous humor production by the ciliary epithelium in vivo. Images PMID:3022303

  2. Deficiency of interleukin-1 receptor antagonist responsive to anakinra.

    PubMed

    Schnellbacher, Charlotte; Ciocca, Giovanna; Menendez, Roxanna; Aksentijevich, Ivona; Goldbach-Mansky, Raphaela; Duarte, Ana M; Rivas-Chacon, Rafael

    2013-01-01

    We describe a 3-month-old infant who presented to our institution with interleukin (IL)-1 receptor antagonist deficiency (DIRA), which consists of neutrophilic pustular dermatosis, periostitis, aseptic multifocal osteomyelitis, and persistently high acute-phase reactants. Skin findings promptly improved upon initiation of treatment with anakinra (recombinant human IL-1 receptor antagonist), and the bony lesions and systemic inflammation resolved with continued therapy. PMID:22471702

  3. Characterization of beta-adrenergic receptors and adenylate cyclase activity in rat brown fat

    SciTech Connect

    Baresi, L.A.; Morley, J.E.; Scarpace, P.J.

    1986-03-01

    Catecholamines stimulate thermogenesis in rat brown fat through a mechanism which involves binding to the beta-adrenergic receptor (BAR), stimulation of adenylate cyclase (AC) and culminating with uncoupling of mitochondrial respiration from ATP synthesis. The authors characterized BAR, AC and cytochrome (cyt) c oxidase in CDF (F-344) interscapular brown fat. Scatchard analysis of (/sup 125/)Iodopindolol binding yields a straight line consistent with a single class of antagonist binding sites with 41.8 +/- 12.0 fmol BAR/mg protein and a K/sub d/ of 118 +/- 15 pM. Binding was both specific and stereospecific. Competition with 1-propranolol (K/sub d/ = 6.7 nM) was 15 times more potent than d-propranolol (K/sub d/ = 103 nM). Competition with isoproterenol (K/sub d/ = 79 nM) was 10 times more potent than epinephrine (K/sub d/ = 820 nM) which was 35 times more potent than norepinephrine (K/sub d/ = 2.9 x 10/sup -5/ M) suggesting predominate beta/sub 2/-type BAR. Cyt c oxidase activity was assessed in brown fat mitochrondrial preparations. The ratio of BAR to cyt c activity was 959 +/- 275 nmol BAR/mol cyc c/min. Isoproterenol (0.1 mM) stimulated AC activity was 24 times GTP (0.1 mM) stimulated AC (98.5 vs 40.7 pmol cAMP/min/mg). NaF-stimulated AC was nine times basal activity (90.5 vs 11.3 pmol cAMP/min/mg). These data demonstrate the presence of a beta-/sub 2/-type BAR coupled to adenylate cyclase in rat brown fat.

  4. Identification and characterization of alpha 1 adrenergic receptors in the canine prostate using (/sup 125/I)-Heat

    SciTech Connect

    Lepor, H.; Baumann, M.; Shapiro, E.

    1987-11-01

    We have recently utilized radioligand receptor binding methods to characterize muscarinic cholinergic and alpha adrenergic receptors in human prostate adenomas. The primary advantages of radioligand receptor binding methods are that neurotransmitter receptor density is quantitated, the affinity of unlabelled drugs for receptor sites is determined, and receptors can be localized using autoradiography on slide-mounted tissue sections. Recently, (/sup 125/I)-Heat, a selective and high affinity ligand with high specific activity (2200 Ci/mmole) has been used to characterize alpha 1 adrenergic receptors in the brain. In this study alpha 1 adrenergic receptors in the dog prostate were characterized using (/sup 125/I)-Heat. The Scatchard plots were linear indicating homogeneity of (/sup 125/I)-Heat binding sites. The mean alpha 1 adrenergic receptor density determined from these Scatchard plots was 0.61 +/- 0.07 fmol/mg. wet wt. +/- S.E.M. The binding of (/sup 125/I)-Heat to canine prostate alpha 1 adrenergic binding sites was of high affinity (Kd = 86 +/- 19 pM). Steady state conditions were reached following an incubation interval of 30 minutes and specific binding and tissue concentration were linear within the range of tissue concentrations assayed. The specificity of (/sup 125/I)-Heat for alpha 1 adrenergic binding sites was confirmed by competitive displacement assays using unlabelled clonidine and prazosin. Retrospective analysis of the saturation experiments demonstrated that Bmax can be accurately calculated by determining specific (/sup 125/I)-Heat binding at a single ligand concentration. (/sup 125/I)-Heat is an ideal ligand for studying alpha 1 adrenergic receptors in the prostate and its favorable properties should facilitate the autoradiographic localization of alpha 1 adrenergic receptors in the prostate.

  5. Allosteric interactions between the oxytocin receptor and the β2-adrenergic receptor in the modulation of ERK1/2 activation are mediated by heterodimerization.

    PubMed

    Wrzal, Paulina K; Devost, Dominic; Pétrin, Darlaine; Goupil, Eugénie; Iorio-Morin, Christian; Laporte, Stéphane A; Zingg, Hans H; Hébert, Terence E

    2012-01-01

    The oxytocin receptor (OTR) and the β(2)-adrenergic receptor (β(2)AR) are key regulators of uterine contraction. These two receptors are targets of tocolytic agents used to inhibit pre-term labor. Our recent study on the nature of OTR- and β(2)AR-mediated ERK1/2 activation in human hTERT-C3 myometrial cells suggested the presence of an OTR/β(2)AR hetero-oligomeric complex (see companion article). The goal of this study was to investigate potential allosteric interactions between OTR and β(2)AR and establish the nature of the interactions between these receptors in myometrial cells. We found that OTR-mediated ERK1/2 activation was attenuated significantly when cells were pretreated with the β(2)AR agonist isoproterenol or two antagonists, propranolol or timolol. In contrast, pretreatment of cells with a third β(2)AR antagonist, atenolol resulted in an increase in OTR-mediated ERK1/2 activation. Similarly, β(2)AR-mediated ERK1/2 activation was strongly attenuated by pretreatment with the OTR antagonists, atosiban and OTA. Physical interactions between OTR and β(2)AR were demonstrated using co-immunoprecipitation, bioluminescence resonance energy transfer (BRET) and protein-fragment complementation (PCA) assays in HEK 293 cells, the latter experiments indicating the interactions between the two receptors were direct. Our analyses suggest physical interactions between OTR and β(2)AR in the context of a new heterodimer pair lie at the heart of the allosteric effects. PMID:21963428

  6. Postischemic Brain Injury Is Attenuated in Mice Lacking the β2-Adrenergic Receptor

    PubMed Central

    Han, Ru-Quan; Ouyang, Yi-Bing; Xu, Lijun; Agrawal, Rani; Patterson, Andrew J.; Giffard, Rona G.

    2013-01-01

    Background Several β-adrenergic receptor (βAR) antagonists have been shown to have neuroprotective effects against cerebral ischemia. However, clenbuterol, a β2AR agonist, was shown to have neuroprotective activity by increasing nerve growth factor expression. We used β2AR knockout mice and a β2 selective antagonist to test the effect of loss of β2ARs on outcome from transient focal cerebral ischemia. Methods Ischemia was induced by the intraluminal suture method, for 60 min of middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. Neurological score was determined at 24 h reperfusion and infarct size was determined by cresyl violet or 2,3,5-triphenyltetrazolium chloride staining. β2AR knockout mice and wild-type congenic FVB/N controls were studied, as well as 2 groups of wild type mice given either ICI 118,551 (0.2 mg/kg) or 0.9% saline intraperitoneally 30 min before MCAO (n = 10 per group). Changes in expression of heat shock protein (Hsp)72 after ischemia were examined by immunohistochemistry and western blots. Results Compared with wild type littermates, infarct volume was decreased by 22.3% in β2AR knockout mice (39.7 ± 10.7 mm3 vs 51.0 ± 11.4 mm3, n = 10/group, P = 0.034) after 60 min of MCAO followed by 24 h reperfusion. Pretreatment with a β2AR selective antagonist, ICI 118,551, also decreased infarct size significantly, by 25.1%, compared with the saline control (32.8 ± 11.9 mm3 vs 43.8 ± 10.3 mm3, n = 10/group, P = 0.041). Neurological scores were also significantly improved in mice lacking the β2AR or pretreated with ICI 118,551. After cerebral ischemia, total levels of Hsp72 and the number of Hsp72 immunopositive cells were greater in mice lacking β2 AR. Conclusion Brain injury is reduced and neurological outcome improved after MCAO in mice lacking the β2AR, or in wild type mice pretreated with a selective β2AR antagonist. This is consistent with a shift away from prosurvival signaling to prodeath signaling in the

  7. β3 adrenergic receptor in the kidney may be a new player in sympathetic regulation of renal function.

    PubMed

    Procino, Giuseppe; Carmosino, Monica; Milano, Serena; Dal Monte, Massimo; Schena, Giorgia; Mastrodonato, Maria; Gerbino, Andrea; Bagnoli, Paola; Svelto, Maria

    2016-09-01

    To date, the study of the sympathetic regulation of renal function has been restricted to the important contribution of β1- and β2-adrenergic receptors (ARs). Here we investigate the expression and the possible physiologic role of β3-adrenergic receptor (β3-AR) in mouse kidney. The β3-AR is expressed in most of the nephron segments that also express the type 2 vasopressin receptor (AVPR2), including the thick ascending limb and the cortical and outer medullary collecting duct. Ex vivo experiments in mouse kidney tubules showed that β3-AR stimulation with the selective agonist BRL37344 increased intracellular cAMP levels and promoted 2 key processes in the urine concentrating mechanism. These are accumulation of the water channel aquaporin 2 at the apical plasma membrane in the collecting duct and activation of the Na-K-2Cl symporter in the thick ascending limb. Both effects were prevented by the β3-AR antagonist L748,337 or by the protein kinase A inhibitor H89. Interestingly, genetic inactivation of β3-AR in mice was associated with significantly increased urine excretion of water, sodium, potassium, and chloride. Stimulation of β3-AR significantly reduced urine excretion of water and the same electrolytes. Moreover, BRL37344 promoted a potent antidiuretic effect in AVPR2-null mice. Thus, our findings are of potential physiologic importance as they uncover the antidiuretic effect of β3-AR stimulation in the kidney. Hence, β3-AR agonism might be useful to bypass AVPR2-inactivating mutations. PMID:27206969

  8. Modeling the Effects of β1-Adrenergic Receptor Blockers and Polymorphisms on Cardiac Myocyte Ca2+ Handling

    PubMed Central

    Amanfu, Robert K.

    2014-01-01

    β-Adrenergic receptor blockers (β-blockers) are commonly used to treat heart failure, but the biologic mechanisms governing their efficacy are still poorly understood. The complexity of β-adrenergic signaling coupled with the influence of receptor polymorphisms makes it difficult to intuit the effect of β-blockers on cardiac physiology. While some studies indicate that β-blockers are efficacious by inhibiting β-adrenergic signaling, other studies suggest that they work by maintaining β-adrenergic responsiveness. Here, we use a systems pharmacology approach to test the hypothesis that in ventricular myocytes, these two apparently conflicting mechanisms for β-blocker efficacy can occur concurrently. We extended a computational model of the β1-adrenergic pathway and excitation-contraction coupling to include detailed receptor interactions for 19 ligands. Model predictions, validated with Ca2+ and Förster resonance energy transfer imaging of adult rat ventricular myocytes, surprisingly suggest that β-blockers can both inhibit and maintain signaling depending on the magnitude of receptor stimulation. The balance of inhibition and maintenance of β1-adrenergic signaling is predicted to depend on the specific β-blocker (with greater responsiveness for metoprolol than carvedilol) and β1-adrenergic receptor Arg389Gly polymorphisms. PMID:24867460

  9. Distribution of beta-adrenergic receptors in failing human myocardium. Implications for mechanisms of down-regulation

    SciTech Connect

    Murphree, S.S.; Saffitz, J.E.

    1989-06-01

    The density of beta-adrenergic receptors is reduced in crude membranes prepared from failing human myocardium. We used quantitative autoradiography of radioligand binding sites in intact tissue slices to determine whether the total tissue content of receptors is reduced and to characterize the transmural distribution of receptors in cardiac myocytes and the coronary vasculature in hearts obtained from nine cardiac transplant patients with severe congestive failure. Binding of (125Iodo)cyanopindolol to transmural slices of human myocardium was rapid, saturable, stereoselective, and displaceable by agonists and antagonists with an appropriate rank order of potency. Binding isotherms in four normal and nine failing ventricles showed a significant reduction in the total tissue content of beta-receptors in failing myocardium (38.3 +/- 2.0 fmol/mg protein) compared with normal tissue (52.4 +/- 1.7 fmol/mg protein, p = 0.038). In the normal ventricles, the greatest receptor density was observed autoradiographically in myocytic regions of the subendocardium. Receptor density of the coronary arterioles was approximately 70% of that in adjacent myocytic regions. The density of binding sites in both myocytic regions and arterioles was diminished in all regions of the failing ventricles, but down-regulation was due primarily to a selective reduction of beta-receptors of subendocardial myocytes (63 +/- 5% of subepicardial receptor density vs. 115 +/- 6% in controls, p less than 0.0001). These observations indicate that down-regulation occurs nonuniformly in the transmural distribution and thus is likely not related simply to elevated circulating catecholamine levels.

  10. Plasticity of α2-adrenergic spinal antinociception following nerve injury: selective, bidirectional interaction with the delta opioid receptor.

    PubMed

    Aira, Zigor; Barrenetxea, Teresa; Buesa, Itsaso; Azkue, Jon Jatsu

    2015-01-12

    Interactions of opioid receptors with other receptor families can be made use of to improve analgesia and reduce adverse effects of opioid analgesics. We investigated interactions of the α2-adrenergic receptor (α2AR) with opioid receptors of the mu (MOR) and delta (DOR) types in the spinal dorsal horn in an animal model of neuropathic pain induced by spinal nerve ligation. Nine days after nerve injury, immunoreactivity for the α2AR subtype A (α2AAR) was increased both in tissue homogenates and at pre- and post-synaptic sites in transverse sections. The efficacy of spinally administered α2AAR agonist guanfacine at reducing C-fiber-evoked field potentials was increased in nerve-ligated rats. This reducing effect was impaired by simultaneous administration of DOR antagonist naltrindole, but not MOR antagonist CTOP, suggesting that concurrent DOR activation was required for α2AAR-mediated inhibition. While DOR agonist deltorphin II and MOR agonist DAMGO both effectively depressed C-fiber-evoked spinal field potentials, DOR- but not MOR-mediated depression was enhanced by subclinical guanfacine. In conscious, nerve-ligated rats, chronically administered deltorphin II produced stable thermal and mechanical antinociception over the 9 following days after nerve injury without apparent signs of habituation. Such an effect was dramatically enhanced by co-administration of a low dose of guanfacine, which reversed thermal and mechanical thresholds to levels near those prior to injury. The results suggest that spinal, α2AAR-mediated antinociception is increased after nerve injury and based on DOR co-activation. We demonstrate in vivo that α2AAR/DOR interaction can be exploited to provide effective behavioral antinociception during neuropathic pain. PMID:25446445

  11. Molecular characterization of a rat alpha 2B-adrenergic receptor.

    PubMed Central

    Zeng, D W; Harrison, J K; D'Angelo, D D; Barber, C M; Tucker, A L; Lu, Z H; Lynch, K R

    1990-01-01

    Alpha 2-adrenergic receptors comprise a heterogeneous population based on pharmacologic and molecular evidence. We have isolated a cDNA clone (pRNG alpha 2) encoding a rat alpha 2-adrenergic receptor. A rat kidney cDNA library was screened with an oligonucleotide complementary to a highly conserved region found in all biogenic amine receptors described to date. The deduced amino acid sequence displays many features of guanyl nucleotide-binding protein-coupled receptors except it does not have a consensus N-linked glycosylation site near the amino terminus. Membranes prepared from COS cells transfected with pRNG alpha 2 DNA display high affinity and saturable binding to [3H]rauwolscine (Kd = 2 nM). Competition curve data analysis shows that RNG alpha 2 protein binds to a variety of adrenergic drugs with the following rank order of potency: yohimbine greater than or equal to chlorpromazine greater than or equal to prazosin greater than or equal to clonidine greater than norepinephrine greater than or equal to oxymetazoline. RNG alpha 2 RNA accumulates in both rat kidney and neonatal rat lung (predominant species is 4000 nucleotides). When a cysteine residue (Cys-169) that is conserved among all members of the seven-transmembrane-region superfamily is changed to phenylalanine, the RNG alpha 2 protein fails to bind [3H]rauwolscine after expression in COS cells. We conclude that pRNG alpha 2 likely represents a cDNA for a rat alpha 2B-adrenergic receptor. Images PMID:2158103

  12. Thyroid-hormone modulation of the number of beta-adrenergic receptors in rat fat-cell membranes.

    PubMed Central

    Giudicelli, Y

    1978-01-01

    Adipocytes from thyroidectomized rats contain 3 times less [3H]dihydroalprenolol-binding sites (beta-adrenergic receptors) than adipocytes from euthyroid animals. This alteration is not solely due to cell-size differences, but also to a thyroidectomy-induced defect in beta-adrenergic receptor density per adipocyte surface area, a defect that is furthermore corrected by tri-iodothyronine treatment. PMID:218550

  13. Discovery of cannabinoid-1 receptor antagonists by virtual screening.

    PubMed

    Lee, Gil Nam; Kim, Kwang Rok; Ahn, Sung-Hoon; Bae, Myung Ae; Kang, Nam Sook

    2010-09-01

    In this work, we tried to find a new scaffold for a CB1 receptor antagonist using virtual screening. We first analyzed structural features for the known cannabinoid-1 receptor antagonists and, then, we built pharmacophore models using the HipHop concept and carried out a docking study based on our homology CB1 receptor 3D structure. The most active compound, including thiazole-4-one moiety, showed an activity value of 125 nM IC(50), with a good PK profile. PMID:20667724

  14. Yohimbine impairs extinction of cocaine-conditioned place preference in an alpha2-adrenergic receptor independent process.

    PubMed

    Davis, Adeola R; Shields, Angela D; Brigman, Jonathan L; Norcross, Maxine; McElligott, Zoe A; Holmes, Andrew; Winder, Danny G

    2008-09-01

    Extinction, a form of learning that has the ability to reshape learned behavior based on new experiences, has been heavily studied utilizing fear learning paradigms. Mechanisms underlying extinction of positive-valence associations, such as drug self-administration and place preference, are poorly understood yet may have important relevance to addiction treatment. Data suggest a major role for the noradrenergic system in extinction of fear-based learning. Employing both pharmacological and genetic approaches, we investigated the role of the alpha(2)-adrenergic receptor (alpha(2)-AR) in extinction of cocaine-conditioned place preference (CPP) and glutamatergic transmission in the bed nucleus of the stria terminalis (BNST). We found that pre-extinction systemic treatment with the alpha(2)-AR antagonist yohimbine impaired cocaine CPP extinction in C57BL/6J mice, an effect that was not mimicked by the more selective alpha(2)-AR antagonist, atipamezole. Moreover, alpha(2A)-AR knockout mice exhibited similar cocaine CPP extinction and exacerbated extinction impairing effects of yohimbine. Using acute brain slices and electrophysiological approaches, we found that yohimbine produces a slowly evolving depression of glutamatergic transmission in the BNST that was not mimicked by atipamezole. Further, this action was extant in slices from alpha(2A)-AR knockout mice. Our data strongly suggest that extinction-modifying effects of yohimbine are unlikely to be due to actions at alpha(2A)-ARs. PMID:18772254

  15. Muscarinic cholinergic and alpha 2-adrenergic receptors in the epithelium and muscularis of the human ileum

    SciTech Connect

    Lepor, H.; Rigaud, G.; Shapiro, E.; Baumann, M.; Kodner, I.J.; Fleshman, J.W. )

    1990-04-01

    The aim of this study was to characterize the binding and functional properties of muscarinic cholinergic (MCh) and alpha 2-adrenergic receptors in the human ileum to provide insight into pharmacologic strategies for managing urinary and fecal incontinence after bladder and rectal replacement with intestinal segments. MCh and alpha 2-adrenergic binding sites were characterized in the epithelium and muscularis of eight human ileal segments with 3H-N-methylscopolamine and 3H-rauwolscine, respectively. The dissociation constant for 3H-N-methylscopolamine in the epithelium and muscularis was 0.32 +/- 0.07 nmol/L and 0.45 +/- 0.10 nmol/L, respectively (p = 0.32). The MCh receptor content was approximately eightfold greater in the muscularis compared with the epithelium (p = 0.008). The dissociation constant for 3H-rauwolscine in the muscularis and epithelium was 2.55 +/- 0.42 nmol/L and 2.03 +/- 0.19 nmol/L, respectively (p = 0.29). The alpha 2-adrenoceptor density was twofold greater in the epithelium compared with the muscularis (p = 0.05). Noncumulative concentration-response experiments were performed with carbachol, an MCh agonist, and UK-14304, a selective alpha 2-adrenergic agonist. The epithelium did not contract in the presence of high concentrations of carbachol and UK-14304. The muscularis preparations were responsive only to carbachol. The muscularis contains primarily MCh receptors mediating smooth muscle contraction. The alpha 2-adrenoceptors are localized primarily to the epithelium and may regulate water secretion in the intestine. The distribution and functional properties of ileal MCh and alpha 2-adrenergic receptors provide a theoretic basis for the treatment of incontinence after bladder and rectal replacement with intestinal segments.

  16. Greater Beta-Adrenergic Receptor Mediated Vasodilation in Women Using Oral Contraceptives

    PubMed Central

    Limberg, Jacqueline K.; Peltonen, Garrett L.; Johansson, Rebecca E.; Harrell, John W.; Kellawan, Jeremy M.; Eldridge, Marlowe W.; Sebranek, Joshua J.; Walker, Benjamin J.; Schrage, William G.

    2016-01-01

    Background: β-adrenergic receptors play an important role in mitigating the pressor effects of sympathetic nervous system activity in young women. Based on recent data showing oral contraceptive use in women abolishes the relationship between muscle sympathetic nervous system activity and blood pressure, we hypothesized forearm blood flow responses to a β-adrenergic receptor agonist would be greater in young women currently using oral contraceptives (OC+, n = 13) when compared to those not using oral contraceptives (OC–, n = 10). Methods: Women (18–35 years) were studied during the early follicular phase of the menstrual cycle (days 1–5) or placebo phase of oral contraceptive use. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured at baseline and during graded brachial artery infusion of the β-adrenergic receptor agonist, Isoproterenol (ISO), as well as Acetylcholine (ACH, endothelium-dependent vasodilation) and Nitroprusside (NTP, endothelium-independent vasodilation). Forearm vascular conductance was calculated (FVC = FBF/MAP, ml/min/100 mmHg) and the rise in FVC from baseline during infusion quantified vasodilation (ΔFVC = FVCinfusion − FVCbaseline). Results: ISO increased FVC in both groups (p < 0.01) and ISO-mediated ΔFVC was greater in OC+ compared to OC– (Main effect of group, p = 0.02). Expressing data as FVC and FBF resulted in similar conclusions. FVC responses to both ACH and NTP were also greater in OC+ compared to OC–. Conclusions: These data are the first to demonstrate greater β-adrenergic receptor-mediated vasodilation in the forearm of women currently using oral contraceptives (placebo phase) when compared to those not using oral contraceptives (early follicular phase), and suggest oral contraceptive use influences neurovascular control. PMID:27375493

  17. Relationship between alpha/sub 1/-adrenergic receptor occupancy and regulation of intracellular Ca/sup + +/ in BC3H-1 muscle cells

    SciTech Connect

    Brown, R.D.; Berger, K.D.; Button, D.; Taylor, P.

    1986-05-01

    The relationship between ..cap alpha../sub 1/-adrenergic receptor occupancy by agonists or antagonists and functional response was examined. Receptor occupancy was measured using the antagonist (/sup 3/H)prazosin, and correlated with agonist-elicited unidirectional /sup 45/Ca/sup + +/ efflux. The agonists epinephrine (E), norepinephrine (NE), and phenylephrine (PE) activated /sup 45/Ca/sup + +/ efflux with the order of potency expected for ..cap alpha../sub 1/ receptors (E greater than or equal to NE > PE). A parabolic relationship suggesting the presence of a modest receptor reserve was observed between the number of activatable receptors after equilibration with specified (/sup 3/H)prazosin concentrations and residual /sup 45/Ca/sup + +/ efflux responses elicited by E or NE. A linear relationship was previously observed for PE. Agonist occupancy was independently measured by competition with the initial rate of (/sup 3/H)prazosin association. Both E and NE inhibited (/sup 3/H)prazosin binding over higher concentration ranges than those required to elicit /sup 45/Ca/sup + +/ efflux. Equilibration of cultures with agonist prior to measurement of (/sup 3/H)prazosin binding resulted in small decreases in apparent agonist affinities. These results indicate that BC3H-1 cells possess a small ..cap alpha../sub 1/-receptor reserve for agonist-elicited /sup 45/Ca/sup + +/ efflux which is reflected in the catecholamine agonists, and that exposure to agonist converts receptors to a state of reduced agonist affinity.

  18. Non-NMDA receptor antagonist-induced drinking in rat

    NASA Technical Reports Server (NTRS)

    Xu, Z.; Johnson, A. K.

    1998-01-01

    Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

  19. Adrenergic Modulation of Pancreatic Glucagon Secretion in Man

    PubMed Central

    Gerich, John E.; Langlois, Maurice; Noacco, Claudio; Schneider, Victor; Forsham, Peter H.

    1974-01-01

    In order to characterize the influence of the adrenergic system on pancreatic glucagon secretion in man, changes in basal glucagon secretion during infusions of pure alpha and beta adrenergic agonists and their specific antagonists were studied. During infusion of isoproterenol (3 μg/min), a beta adrenergic agonist, plasma glucagon rose from a mean (±SE) basal level of 104±10 to 171±15 pg/ml, P < 0.0002. Concomitant infusion of propranolol (80 μg/min), a beta adrenergic antagonist, prevented the effects of isoproterenol, although propranolol itself had no effect on basal glucagon secretion. During infusion of methoxamine (0.5 mg/min), an alpha adrenergic agonist, plasma glucagon declined from a mean basal level of 122±15 to 75±17 pg/ml, P < 0.001. Infusion of phentolamine (0.5 mg/min), an alpha adrenergic antagonist, caused a rise in plasma glucagon from a mean basal level of 118±16 to 175±21 pg/ml, P < 0.0001. Concomitant infusion of methoxamine with phentolamine caused a reversal of the effects of phentolamine. The present studies thus confirm that catecholamines affect glucagon secretion in man and demonstrate that the pancreatic alpha cell possesses both alpha and beta adrenergic receptors. Beta adrenergic stimulation augments basal glucagon secretion, while alpha adrenergic stimulation diminishes basal glucagon secretion. Furthermore, since infusion of phentolamine, an alpha adrenergic antagonist, resulted in an elevation of basal plasma glucagon levels, there appears to be an inhibitory alpha adrenergic tone governing basal glucagon secretion. The above findings suggest that catecholamines may influence glucose homeostasis in man through their effects on both pancreatic alpha and beta cell function. Images PMID:4825234

  20. Can Specific Protein-Lipid Interactions Stabilize an Active State of the Beta 2 Adrenergic Receptor?

    PubMed

    Neale, Chris; Herce, Henry D; Pomès, Régis; García, Angel E

    2015-10-20

    G-protein-coupled receptors are eukaryotic membrane proteins with broad biological and pharmacological relevance. Like all membrane-embedded proteins, their location and orientation are influenced by lipids, which can also impact protein function via specific interactions. Extensive simulations totaling 0.25 ms reveal a process in which phospholipids from the membrane's cytosolic leaflet enter the empty G-protein binding site of an activated β2 adrenergic receptor and form salt-bridge interactions that inhibit ionic lock formation and prolong active-state residency. Simulations of the receptor embedded in an anionic membrane show increased lipid binding, providing a molecular mechanism for the experimental observation that anionic lipids can enhance receptor activity. Conservation of the arginine component of the ionic lock among Rhodopsin-like G-protein-coupled receptors suggests that intracellular lipid ingression between receptor helices H6 and H7 may be a general mechanism for active-state stabilization. PMID:26488656

  1. Molecular dynamics of a biophysical model for beta2-adrenergic and G protein-coupled receptor activation.

    PubMed

    Rubenstein, Lester A; Zauhar, Randy J; Lanzara, Richard G

    2006-12-01

    This study analyzes 16 molecular dynamic simulations of a biophysical model for beta(2)-adrenergic (B2AR) and G protein-coupled receptor (GPCR) activation. In this model, a highly conserved cysteine residue, C106 (C3.25 or CysIII:01), provides a free sulfhydryl or thiol group in an acid-base equilibrium between uncharged (RSH) and charged (RS(-)) states that functions as an electrostatic molecular switch for receptor activation. The transition of C106 in the B2AR between acid and base states significantly changes the helical/transmembrane (TM) domain interactions and the electrostatic interaction energy differences (DeltaDeltaE(EL)). The DeltaDeltaE(EL) changes correlate well with the experimentally observed ligand efficacies. The TM interaction energies display patterns compatible with those previously recognized as responsible for GPCR activation. Key differences between the agonist, epinephrine, and the antagonist, pindolol, are seen for the TM3 x 6, TM3 x 4, TM6 x 7 and TM1 x 7 interaction energies. Pindolol also produces a weaker DeltaDeltaE(EL) interaction and less TM interaction energy changes, which are important differences between the agonist and antagonist ligands. The D115E mutant with pindolol displays a greater DeltaDeltaE(EL) and TM interactions than for the wild-type B2AR with pindolol. This explains the higher activity of pindolol in the D115E mutant. The constitutively active D130A mutant displays TM interaction patterns similar to those for the activating ligands implying a common pattern for receptor activation. These findings support the broad concept of protean agonism and demonstrate the potential for allosteric modulation. They also demonstrate that this two-state model agrees with many previous experimental and theoretical observations of GPCRs. PMID:16574446

  2. Azogabazine; a photochromic antagonist of the GABAA receptor.

    PubMed

    Huckvale, Rosemary; Mortensen, Martin; Pryde, David; Smart, Trevor G; Baker, James R

    2016-07-12

    The design and synthesis of azogabazine is described, which represents a highly potent (IC50 = 23 nM) photoswitchable antagonist of the GABAA receptor. An azologization strategy is adopted, in which a benzyl phenyl ether in a high affinity gabazine analogue is replaced by an azobenzene, with resultant retention of antagonist potency. We show that cycling from blue to UV light, switching between trans and cis isomeric forms, leads to photochemically controlled antagonism of the GABA ion channel. PMID:27327397

  3. Dopamine binds to α2-adrenergic receptors in the song control system of zebra finches (Taeniopygia guttata)

    PubMed Central

    Cornil, Charlotte A.; Castelino, Christina B.; Ball, Gregory F.

    2008-01-01

    A commonly held view is that dopamine exerts its effects via binding to D1- and D2-dopaminergic receptors. However, recent data have emerged supporting the existence of a direct interaction of dopamine with adrenergic receptors. Dopamine may also directly bind adrenergic receptors but this interaction has been poorly investigated. In this study, the pharmacological basis of possible in vivo interactions between dopamine and α2-adrenergic receptors was investigated in zebra finches. A binding competition study showed that dopamine displaces the binding of the selective α2-adrenergic ligand, [3H]RX821002, in the brain. The affinity of dopamine for the adrenergic sites does not differ between the sexes and is 10-28-fold lower than that for norepinephrine. To assess the anatomical distribution of this interaction, binding competitions were performed on brain slices incubated in 5nM [3H]RX821002 in the absence of any competitor or in the presence of norepinephrine or dopamine. Both norepinephrine and dopamine displaced the binding of the radioligand though to a different extent in most of the regions studied (e.g., Area X, the lateral part of the magnocellular nucleus of anterior nidopallium, HVC, arcopallium dorsale, ventral tegmental area and substantia grisea centralis) but not in the robust nucleus of the arcopallium. Together these data provide evidence for a direct interaction between dopamine and adrenergic receptors in songbird brains albeit with regional variation. PMID:18155403

  4. Beta-adrenergic antagonists during general anesthesia reduced postoperative pain: a systematic review and a meta-analysis of randomized controlled trials.

    PubMed

    Härkänen, Lasse; Halonen, Jari; Selander, Tuomas; Kokki, Hannu

    2015-12-01

    We have performed a systematic literature review and a meta-analysis investigating the effect of beta-adrenergic antagonist on perioperative pain in randomized clinical trials (RCTs). The search included the CENTRAL, CINAHL, EMBASE, and MEDLINE databases (from inception to 10 February 2015). From the retrieved full texts, we hand-searched the references and PubMed related citations. A total of 11 RCTs consisting data of 701 adult patients were eligible for this systematic review. Esmolol was evaluated in ten trials and propranolol in one. Esmolol decreased the need for rescue analgesics by 32-50%; p < 0.05 (n = 7) and the proportion of patients needing rescue analgesia from 100 to 65%; p < 0.005 (n = 1), and propranolol decreased the need for rescue analgesics by 72%; p < 0.001 (n = 1). The time to the first rescue analgesics was longer (p < 0.05) and pain ratings were lower (p < 0.05) in patients with beta-adrenergic antagonists. However, in two opioid-controlled studies, one in knee arthroscopy and another in tubal ligation patients, the proportion of patients needing rescue analgesia was two-times higher in esmolol-treated patients: 52-57 vs. 23-34%, p < 0.05. Adverse effects were rarely reported, and as reported were mostly cardiovascular alterations. In conclusion, intra-operative beta-adrenergic antagonists' administration may decrease postoperative pain and analgesic consumption when given as an adjuvant to general anesthesia. PMID:26160590

  5. Molecular and biological interaction between major histocompatibility complex class I antigens and luteinizing hormone receptors or beta-adrenergic receptors triggers cellular response in mice.

    PubMed Central

    Solano, A R; Cremaschi, G; Sánchez, M L; Borda, E; Sterin-Borda, L; Podestá, E J

    1988-01-01

    Purified IgG from BALB/c mouse anti-C3H serum exerts positive inotropic and chronotropic effects in C3H mouse atria and induces testosterone synthesis in C3H mouse Leydig cells. The effect depends on IgG concentration and can be abolished by beta-adrenergic-receptor and luteinizing hormone-receptor antagonists. IgG interferes with the binding of dihydroalprenolol and luteinizing hormone. Monoclonal antibodies against major histocompatibility complex class I antigens were active on the Leydig cells of C3H and BALB/c mice. There was a parallelism between the effect of each individual monoclonal antibody with specificity for a particular haplotype and the response of the target cell from the strains carrying such haplotypes. These antibodies could precipitate the soluble luteinizing hormone-receptor complex. The results suggested that bound hormone triggers the association of major histocompatibility class I antigen with the receptor, thereby activating the respective target cells. PMID:2839829

  6. Some sweet and bitter tastants stimulate inhibitory pathway of adenylyl cyclase via melatonin and alpha 2-adrenergic receptors in Xenopus laevis melanophores.

    PubMed

    Zubare-Samuelov, Meirav; Peri, Irena; Tal, Michael; Tarshish, Mark; Spielman, Andrew I; Naim, Michael

    2003-11-01

    The sweeteners saccharin, D-tryptophan, and neohesperidin dihydrochalcone (NHD) and the bitter tastant cyclo(Leu-Trp) stimulated concentration-dependent pigment aggregation in a Xenopus laevis melanophore cell line similar to melatonin. Like melatonin, these tastants inhibited (by 45-92%) cAMP formation in melanophores; pertussis toxin pretreatment almost completely abolished the tastant-induced cAMP inhibition, suggesting the involvement of the inhibitory pathway (Gi) of adenylyl cyclase. The presence of luzindole (melatonin receptor antagonist) almost completely abolished the inhibition of cAMP formation induced by saccharin, D-tryptophan, and cyclo(Leu-Trp) but only slightly affected the inhibitory effect of NHD. In contrast, the presence of an alpha2-adrenergic receptor antagonist, yohimbine, almost completely abolished the inhibition of cAMP formation induced by NHD but had only a minor effect on that induced by the other tastants. Thus saccharin, D-tryptophan, and cyclo(Leu-Trp) are melatonin receptor agonists whereas NHD is an alpha2-adrenergic receptor agonist, but both pathways lead to the same transduction output and cellular response. Formation of D-myo-inositol 1,4,5-trisphosphate (IP3) in melanophores was reduced (15-58%, no concentration dependence) by saccharin, D-tryptophan, and cyclo(Leu-Trp) stimulation but increased by NHD stimulation. Tastant stimulation did not affect cGMP. Although some of the above tastants were found to be membrane permeant, their direct activation of downstream transduction components in this experimental system is questionable. MT1 and MT2 melatonin receptor mRNAs were identified in rat circumvallate papilla taste buds and nonsensory epithelium, suggesting the occurrence of MT1 and MT2 receptors in these tissues. Melatonin stimulation reduced the cellular content of cAMP in taste cells, which may or may not be related to taste sensation. PMID:12839835

  7. Quantification of ligand bias for clinically relevant β2-adrenergic receptor ligands: implications for drug taxonomy.

    PubMed

    van der Westhuizen, Emma T; Breton, Billy; Christopoulos, Arthur; Bouvier, Michel

    2014-03-01

    The concepts of functional selectivity and ligand bias are becoming increasingly appreciated in modern drug discovery programs, necessitating more informed approaches to compound classification and, ultimately, therapeutic candidate selection. Using the β2-adrenergic receptor as a model, we present a proof of concept study that assessed the bias of 19 β-adrenergic ligands, including many clinically used compounds, across four pathways [cAMP production, extracellular signal-regulated kinase 1/2 (ERK1/2) activation, calcium mobilization, and receptor endocytosis] in the same cell background (human embryonic kidney 293S cells). Efficacy-based clustering placed the ligands into five distinct groups with respect to signaling signatures. In some cases, apparent functional selectivity originated from off-target effects on other endogenously expressed adrenergic receptors, highlighting the importance of thoroughly assessing selectivity of the responses before concluding receptor-specific ligand-biased signaling. Eliminating the nonselective compounds did not change the clustering of the 10 remaining compounds. Some ligands exhibited large differences in potency for the different pathways, suggesting that the nature of the receptor-effector complexes influences the relative affinity of the compounds for specific receptor conformations. Calculation of relative effectiveness (within pathway) and bias factors (between pathways) for each of the compounds, using an operational model of agonism, revealed a global signaling signature for all of the compounds relative to isoproterenol. Most compounds were biased toward ERK1/2 activation over the other pathways, consistent with the notion that many proximal effectors converge on this pathway. Overall, we demonstrate a higher level of ligand texture than previously anticipated, opening perspectives for the establishment of pluridimensional correlations between signaling profiles, drug classification, therapeutic efficacy, and

  8. The effect of CA1 α2 adrenergic receptors on memory retention deficit induced by total sleep deprivation and the reversal of circadian rhythm in a rat model.

    PubMed

    Norozpour, Yaser; Nasehi, Mohammad; Sabouri-Khanghah, Vahid; Torabi-Nami, Mohammad; Zarrindast, Mohammad-Reza

    2016-09-01

    The α2 adrenergic receptors which abundantly express in the CA1 region of the hippocampus play an important role in the regulation of sleep and memory retention processes. Based on the available evidence, the aim of our study was to investigate consequences of the activation and deactivation of CA1 α2 adrenergic receptors (by clonidine and yohimbine, respectively) on the impairment of memory retention induced by total sleep deprivation (TSD) and the reversal of circadian rhythm (RCR) in a rat model. To this end, the water box apparatus and passive avoidance task were in turn used to induce sleep deprivation and assess memory retention. Our findings suggested that TSD (for 24 and 36, but not 12h) and RCR (12h/day for 3 consecutive days) impair memory function. The post-training intra-CA1 administration of yohimbine (α2 adrenergic receptor antagonist) on its own, at the dose of 0.1μg/rat, decreased the step-through latency and locomotor activity in the TSD- sham treated but not undisturbed sleep rats. Unlike yohimbine, clonidine (α2 adrenergic receptor agonist), in all applied doses (0.001, 0.01 and 0.1μg/rat), failed to induce such an effect. While the subthreshold dose of yohimbine (0.001μg/rat) abrogated the impairment of memory retention induced by the 24-h TSD, it could potentiate the impairment of memory retention induced by 36-h TSD, suggesting the modulatory effect of yohimbine. Moreover, the subthreshold dose of clonidine (0.1μg/rat) restored the memory retention deficit in TSD rats (24 and 36h). On the other hand, the subthreshold dose of clonidine (0.1μg/rat), but not yohimbine (0.001μg/rat) restored the memory retention deficit in RCR rats. Such interventions however did not alter the locomotor activity. The above observations proposed that CA1 α2 adrenergic receptors play a potential role in memory retention deficits induced by TSD and RCR. PMID:27291858

  9. Fluorescent Human EP3 Receptor Antagonists.

    PubMed

    Tomasch, Miriam; Schwed, J Stephan; Kuczka, Karina; Meyer Dos Santos, Sascha; Harder, Sebastian; Nüsing, Rolf M; Paulke, Alexander; Stark, Holger

    2012-09-13

    Exchange of the lipophilc part of ortho-substituted cinnamic acid lead structures with different small molecule fluorophoric moieties via a dimethylene spacer resulted in hEP3R ligands with affinities in the nanomolar concentration range. Synthesized compounds emit fluorescence in the blue, green, and red range of light and have been tested concerning their potential as a pharmacological tool. hEP3Rs were visualized by confocal laser scanning microscopy on HT-29 cells, on murine kidney tissues, and on human brain tissues and functionally were characterized as antagonists on human platelets. Inhibition of PGE2 and collagen-induced platelet aggregation was measured after preincubation with novel hEP3R ligands. The pyryllium-labeled ligand 8 has been shown as one of the most promising structures, displaying a useful fluorescence and highly affine hEP3R antagonists. PMID:24900547

  10. Epinephrine effects on mitochondrial Krebs cycle are not mediated by typical adrenergic receptors in isolated rat hepatocytes

    SciTech Connect

    Mohan, C.; Memon, R.A.; Bessman, S.P. )

    1990-02-26

    Oxidation of 2,3-{sup 14}C succinate (suc) carbons in the intra-mitochondrial Krebs cycle was used as a probe to investigate the effects of epinephrine (epi) on isolated rat hepatocytes. Hepatocytes were incubated at 30{degrees}C in Krebs-Henseleit bicarbonate buffer, pH 7.4, with 0.5 mM concentration of each of the 20 natural amino acids, 0.5 mm concentration of each of the 20 natural amino acids, 2,3-{sup 14}C suc and epi (10 uM), phenylephrine (pheni) (10uM) or isoproterenol (10 uM). Epi and phepi caused a significant increase in {sup 14}CO{sub 2} formation from 2,3-{sup 14}C suc, however, phentolamine, an {infinity}-antagonist, failed to inhibit this increased oxidation of suc carbons. Isoproterenol had no effect on hepatocyte metabolism and propranolol, a {beta}-antagonist, failed to cause any reduction in basal or epi stimulated oxidation of 2,3-{sup 14}C carbons. Unlike insulin, neither epi nor phepi had any significant effect on the anabolic utilization of suc carbons for protein or lipid synthesis. Anabolic channeling of Krebs cycle intermediates into amino acids was reduced by epi treatment of hepatocytes. Although epi treatment can enhance the oxidation of substrate through the Krebs cycle reactions, only insulin is capable of channeling these substrates into anabolic reactions. Data presented also suggest that epi effects on mitochondrial Krebs cycle oxidation are mediated through an atypical {infinity}-adrenergic receptor which is unresponsive to inhibition by non-selective {infinity}-antagonists.

  11. Cholestasis of pregnancy, pruritus and 5-hydroxytryptamine 3 receptor antagonists.

    PubMed

    Schumann, Roman; Hudcova, Jana

    2004-09-01

    Pruritus, an early symptom of intrahepatic cholestasis of pregnancy, may be severe. Conventional treatment includes ursodeoxycholic acid and cholestyramine. Ondansetron, a 5-hydroxytryptamine 3 receptor antagonist antiemetic, has been shown to reduce pruritus of different etiologies including cholestasis. We now report the successful preoperative use of ondansetron in a patient with pruritus from intrahepatic cholestasis of pregnancy. While the mechanism for our patient's response is poorly understood, 5-hydroxytryptamine 3 receptor antagonists should be further evaluated and possibly considered as a treatment option for intrahepatic cholestasis of pregnancy-related pruritus. PMID:15315599

  12. Discovery of Tertiary Sulfonamides as Potent Liver X Receptor Antagonists

    SciTech Connect

    Zuercher, William J.; Buckholz†, Richard G.; Campobasso, Nino; Collins, Jon L.; Galardi, Cristin M.; Gampe, Robert T.; Hyatt, Stephen M.; Merrihew, Susan L.; Moore, John T.; Oplinger, Jeffrey A.; Reid, Paul R.; Spearing, Paul K.; Stanley, Thomas B.; Stewart, Eugene L.; Willson, Timothy M.

    2010-08-12

    Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

  13. Histamine 2 Receptor Antagonists and Proton Pump Inhibitors.

    PubMed

    Brinkworth, Megan D; Aouthmany, Mouhammad; Sheehan, Michael

    2016-01-01

    Within the last 50 years, the pharmacologic market for gastric disease has grown exponentially. Currently, medical management with histamine 2 receptor antagonist and proton pump inhibitors are the mainstay of therapy over surgical intervention. These are generally regarded as safe medications, but there are growing numbers of cases documenting adverse effects, especially those manifesting in the skin. Here we review the pharmacology, common clinical applications, and adverse reactions of both histamine 2 receptor antagonists and proton pump inhibitors with a particular focus on the potential for allergic reactions including allergic contact dermatitis. PMID:27172303

  14. Postendocytic Sorting of Adrenergic and Opioid Receptors: New Mechanisms and Functions.

    PubMed

    Bowman, Shanna L; Puthenveedu, Manojkumar A

    2015-01-01

    The endocytic pathway tightly regulates the activity of G protein-coupled receptors (GPCRs). Much of our understanding of this relationship between GPCR endocytic trafficking and signaling comes from studies done on catecholamine and opioid receptors. After ligand-induced endocytosis, a key sorting step in the endosome determines whether receptors are recycled back to the cell surface, leading to recovery of signaling, or are degraded in the lysosome, leading to desensitization. Recycling of GPCRs, unlike that of many other proteins, is an active process driven by specific sequences on the receptor and proteins that interact with this sequence. Recent data suggest that sequence-dependent recycling plays complex roles in regulating both the timing and location of GPCR signaling. This chapter will describe our current understanding of the mechanisms regulating GPCR sorting in the endosome and discuss emerging ideas on their role in GPCR signaling, focusing on adrenergic and opioid receptors as prototypes. PMID:26055059

  15. Beta-adrenergic receptor density and adenylate cyclase activity in lead-exposed rat brain after cessation of lead exposure.

    PubMed

    Chang, Huoy-Rou; Tsao, Der-An; Yu, Hsin-Su; Ho, Chi-Kung

    2005-01-01

    To understanding the reversible or irreversible harm to the beta-adrenergic system in the brain of lead-exposed rats, this study sets up an animal model to estimate the change in the sympathetic nervous system of brain after lead exposure was withdrawn. We address the following topics in this study: (a) the relationship between withdrawal time of lead exposure and brain beta-adrenergic receptor, blood lead level, and brain lead level in lead-exposed rats after lead exposure was stopped; and (b) the relationship between lead level and beta-adrenergic receptor and cyclic AMP (c-AMP) in brain. Wistar rats were chronically fed with 2% lead acetate and water for 2 months. Radioligand binding was assayed by a method that fulfilled strict criteria of beta-adrenergic receptor using the ligand [125I]iodocyanopindolol. The levels of lead were determined by electrothermal atomic absorption spectrometry. The c-AMP level was determined by radioimmunoassay. The results showed a close relationship between decreasing lead levels and increasing numbers of brain beta-adrenergic receptors and brain adenylate cyclase activity after lead exposure was withdrawn. The effect of lead exposure on the beta-adrenergic system of the brain is a partly reversible condition. PMID:15502967

  16. Contribution of β-adrenergic receptors to exercise-induced bronchodilatation in healthy humans.

    PubMed

    Antonelli, Andrea; Torchio, Roberto; Bertolaccini, Luca; Terzi, Alberto; Rolfo, Fabrizio; Agostoni, Piergiuseppe; Gulotta, Carlo; Brusasco, Vito; Pellegrino, Riccardo

    2012-10-15

    Exercise in healthy subjects is usually associated with progressive bronchodilatation. Though the decrease in vagal tone is deemed to be the main underlying mechanism, activation of bronchial β(2)-receptors may constitute an additional cause. To examine the contribution of β(2)-adrenergic receptors to bronchodilatation during exercise in healthy humans, we studied 15 healthy male volunteers during maximum exercise test at control conditions and after a non-selective β-adrenergic blocker (carvedilol 12.5mg twice a day until heart rate decreased at least by 10beats/min) and inhaled β(2)-agonist (albuterol 400μg). Airway caliber was estimated from the partial flow at 40% of control forced vital capacity (V˙(part40)) and its changes during exercise from the slope of linear regression analysis of V˙(part40) values against the corresponding minute ventilation during maximal exercise until exhaustion. At control, V˙(part40) increased progressively and significantly with exercise. After albuterol, resting V˙(part40) was significantly larger than at control increased but did not further increase during exercise. After carvedilol, V˙(part40) was similar to control but its increase with exercise was significantly attenuated. These findings suggest that β(2)-adrenergic system plays a major role in exercise-induced bronchodilation in healthy subjects. PMID:22842007

  17. Nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone induce cyclooxygenase-2 activity in human gastric cancer cells: Involvement of nicotinic acetylcholine receptor (nAChR) and {beta}-adrenergic receptor signaling pathways

    SciTech Connect

    Shin, Vivian Yvonne; Jin, H.C.; Ng, Enders K.O.; Yu Jun; Leung, W.K.; Cho, C.H.; Sung, J.J.Y.

    2008-12-01

    Induction of cyclooxygenase-2 (COX-2) associates with cigarette smoke exposure in many malignancies. Nicotine and its derivative, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are the two important components in cigarette smoke that contributes to cancer development. However, the molecular mechanism(s) by which nicotine or NNK promotes gastric carcinogenesis remains largely unknown. We found that nicotine and NNK significantly enhanced cell proliferation in AGS cells that expressed both alpha7 nicotinic acetylcholine receptor ({alpha}7 nAChR) and {beta}-adrenergic receptors. Treatment of cells with {alpha}-bungarotoxin ({alpha}-BTX, {alpha}7nAChR antagonist) or propranolol ({beta}-adrenergic receptor antagonist) blocked NNK-induced COX-2/PGE{sub 2} and cell proliferation, while nicotine-mediated cell growth and COX-2/PGE{sub 2} induction can only be suppressed by propranolol, but not {alpha}-BTX. Moreover, in contrast to the dependence of growth promoting effect of nicotine on Erk activation, inhibitor of p38 mitogen-activated protein kinase (MAPK) repressed NNK-induced COX-2 upregulation and resulted in suppression of cell growth. In addition, nicotine and NNK mediated COX-2 induction via different receptors to modulate several G1/S transition regulatory proteins and promote gastric cancer cell growth. Selective COX-2 inhibitor (SC-236) caused G1 arrest and abrogated nicotine/NNK-induced cell proliferation. Aberrant expression of cyclin D1 and other G1 regulatory proteins are reversed by blockade of COX-2. These results pointed to the importance of adrenergic and nicotinic receptors in gastric tumor growth through MAPK/COX-2 activation, which may perhaps provide a chemoprevention strategy for cigarette smoke-related gastric carcinogenesis.

  18. Prognostic significance of β2-adrenergic receptor expression in malignant melanoma.

    PubMed

    Shimizu, Akira; Kaira, Kyoichi; Mori, Keita; Kato, Madoka; Shimizu, Kimihiro; Yasuda, Masahito; Takahashi, Ayumi; Oyama, Tetsunari; Asao, Takayuki; Ishikawa, Osamu

    2016-05-01

    Recent studies cite β2-adrenergic receptor (β2AR) antagonists as novel therapeutic agents for melanoma, as they may reduce the disease progression. The β2AR has shown to be expressed in malignant melanoma. However, it remains unclear whether the β2AR expression has a clinical and pathological significance in patients with cutaneous malignant melanoma. We herein conducted a clinicopathological study to investigate the protein expression of β2AR in malignant melanoma of the skin and its prognostic significance. One hundred thirty-three patients with surgically resected cutaneous malignant melanoma were evaluated. Tumor sections were stained by immunohistochemistry for β2AR, Ki-67, the microvessel density (MVD) determined by CD34, and p53. β2AR was highly expressed in 44.4 % (59 out of 133) of the patients. The expression of β2AR was significantly associated with the tumor thickness, ulceration, T factor, N factor, disease stage, tumor size, cell proliferation (Ki-67), and MVD (CD34). Using Spearman's rank test, the β2AR expression was correlated with Ki-67 (r = 0.278; 95 % CI, 0.108 to 0.432; P = 0.001), CD34 (r = 0.445; 95 %CI, 0.293 to 0.575; P < 0.001), and the tumor size (r = 0.226; 95 % CI, 0.053 to 0.386; P = 0.008). Using a univariate analysis, the tumor thickness, ulceration, disease stage, β2AR, Ki-67, and CD34 had a significant relationship with the overall and progression-free survivals. A multivariable analysis confirmed that β2AR was an independent prognostic factor for predicting a poor overall survival (HR 1.730; 95 % CI 1.221-2.515) and progression-free survival (HR 1.576; 95 % CI 1.176-2.143) of malignant melanoma of the skin. β2AR can serve as a promising prognostic factor for predicting a worse outcome after surgical treatment and may play an important role in the development and aggressiveness of malignant melanoma. PMID:26596834

  19. Neuroprotection by NMDA receptor antagonists in a variety of neuropathologies.

    PubMed

    Palmer, G C

    2001-09-01

    Because of adverse reactions, early efforts to introduce high affinity competitive or use-dependent NMDA receptor antagonists into patients suffering from stroke, head trauma or epilepsy met with failure. Later it was discovered that both low affinity use-dependent NMDA receptor antagonists and compounds with selective affinity for the NR2B receptor subunit met the criteria for safe administration into patients. Furthermore, these low affinity antagonists exhibit significant mechanistic differences from their higher affinity counterparts. Success of the latter is attested to the ability of the following low affinity compounds to be marketed: 1) Cough suppressant-dextromethorphan (available for decades); 2) Parkinson's disease--amantadine, memantine and budipine; 3) Dementia--memantine; and 4) Epilepsy--felbamate. Moreover, Phase III clinical trials are ongoing with remacemide for epilepsy and Huntington's disease and head trauma for HU-211. A host of compounds are or were under evaluation for the possible treatment of stroke, head trauma, hyperalgesia and various neurodegenerative disorders. Despite the fact that other drugs with associated NMDA receptor mechanisms have reached clinical status, this review focuses only on those competitive and use-dependent NMDA receptor antagonists that reached clinical trails. The ensuing discussions link the in vivo pharmacological investigations that led to the success/mistakes/ failures for eventual testing of promising compounds in the clinic. PMID:11554551

  20. Cardiac beta-adrenergic receptors and coronary hemodynamics in the conscious dog during hypoxic hypoxia.

    NASA Technical Reports Server (NTRS)

    Erickson, H. H.; Stone, H. L.

    1972-01-01

    The mechanisms by which acute hypoxia (10% and 5% oxygen) mediates changes in coronary blood flow and cardiac function were investigated in the conscious dog. When the dogs breathed hypoxic gas mixtures through a tracheostomy, both arterial and coronary sinus oxygen tensions were significantly decreased. With 5% oxygen, there were significant increases in heart rate (25%), maximum left ventricular dP/dt (39%), left circumflex coronary artery blood flow (163%), and left ventricular oxygen consumption (52%), which were attenuated by beta-adrenergic blockage with propranolol. When electrical pacing was used to keep the ventricular rate constant during hypoxia, there was no significant difference in coronary blood flow before and after beta blockade. Beta-adrenergic receptor activity in the myocardium participates in the integrated response to hypoxia although it may not cause active vasodilation of the coronary vessels.

  1. Alpha adrenergic receptors in dog coronary arteries as detected with autoradiography

    SciTech Connect

    Muntz, K.; Calianos, T.; Buja, L.M.

    1986-03-05

    The authors used previously established methods to determine the presence of alpha adrenergic receptors in different sizes of dog coronary arteries using autoradiography of /sup 3/H-prazosin (PRAZ) and /sup 125/I-BE 2254 (HEAT) to label alpha/sub 1/ adrenergic receptors and /sup 3/H-rauwolscine (RAUW) to label alpha/sub 2/ adrenergic receptors. Frozen sections of the left main coronary artery (LMA), the left anterior descending artery (LAD) and myocardium were incubated in 3 concentrations of PRAZ (0.1, 0.5 and 1.0 nM) (n=5 dogs), 3 concentrations of RAUW (1, 3 and 5 nM) (n=5) and one concentration of HEAT (50 pM) (n=3). All incubations were done in the absence of (total binding) or presence of (nonspecific binding) 10/sup -5/ M phentolamine or yohimbine. The sections were processed for autoradiography and silver grains quantitated using an image analyzer. Analysis of variance determined that there was a significant difference between total and nonspecific binding in the LMA incubated with PRAZ (p < 0.016), but no significant difference between total and nonspecific binding in the LAD (p < 0.19) or in the arterioles (p < 0.68). In the experiments with HEAT, similar results were obtained. With RAUW, there was significant labeling of arterioles (p < 0.004), but not over the LAD (p < 0.11) or the LMA (p < 0.49). The results suggest that the number of coronary alpha/sub 1/ receptors decreases as vessel size decreases, while the number of alpha/sub 2/ receptors increases as vessel size decreases.

  2. The Multitarget Ligand 3-Iodothyronamine Modulates β-Adrenergic Receptor 2 Signaling

    PubMed Central

    Dinter, Juliane; Khajavi, Noushafarin; Mühlhaus, Jessica; Wienchol, Carolin Leonie; Cöster, Maxi; Hermsdorf, Thomas; Stäubert, Claudia; Köhrle, Josef; Schöneberg, Torsten; Kleinau, Gunnar; Mergler, Stefan; Biebermann, Heike

    2015-01-01

    Background 3-Iodothyronamine (3-T1AM), a signaling molecule with structural similarities to thyroid hormones, induces numerous physiological responses including reversible body temperature decline. One target of 3-T1AM is the trace amine-associated receptor 1 (TAAR1), which is a member of the rhodopsin-like family of G protein-coupled receptors (GPCRs). Interestingly, the effects of 3-T1AM remain detectable in TAAR1 knockout mice, suggesting further targets for 3-T1AM such as adrenergic receptors. Therefore, we evaluated whether β-adrenergic receptor 1 (ADRB1) and 2 (ADRB2) signaling is affected by 3-T1AM in HEK293 cells and in human conjunctival epithelial cells (IOBA-NHC), where these receptors are highly expressed endogenously. Methods A label-free EPIC system for prescreening the 3-T1AM-induced effects on ADRB1 and ADRB2 in transfected HEK293 cells was used. In addition, ADRB1 and ADRB2 activation was analyzed using a cyclic AMP assay and a MAPK reporter gene assay. Finally, fluorescence Ca2+ imaging was utilized to delineate 3-T1AM-induced Ca2+ signaling. Results 3-T1AM (10−5−10−10M) enhanced isoprenaline-induced ADRB2-mediated Gs signaling but not that of ADRB1-mediated signaling. MAPK signaling remained unaffected for both receptors. In IOBA-NHC cells, norepinephrine-induced Ca2+ influxes were blocked by the nonselective ADRB blocker timolol (10 µM), indicating that ADRBs are most likely linked with Ca2+ channels. Notably, timolol was also found to block 3-T1AM (10−5M)-induced Ca2+ influx. Conclusions The presented data support that 3-T1AM directly modulates β-adrenergic receptor signaling. The relationship between 3-T1AM and β-adrenergic signaling also reveals a potential therapeutic value for suppressing Ca2+ channel-mediated inflammation processes, occurring in eye diseases such as conjunctivitis. PMID:26601070

  3. Phosphorylation and desensitization of alpha1d-adrenergic receptors.

    PubMed Central

    García-Sáinz, J A; Vázquez-Cuevas, F G; Romero-Avila, M T

    2001-01-01

    In rat-1 fibroblasts stably expressing rat alpha(1d)-adrenoceptors, noradrenaline and PMA markedly decreased alpha(1d)-adrenoceptor function (noradrenaline-elicited increases in calcium in whole cells and [(35)S]guanosine 5'-[gamma-thio]triphosphate binding in membranes), suggesting homologous and heterologous desensitizations. Photoaffinity labelling, Western blotting and immunoprecipitation identified alpha(1d)-adrenoceptors as a broad band of 70-80 kDa. alpha(1d)-Adrenoceptors were phosphorylated in the basal state and noradrenaline and PMA increased it. The effect of noradrenaline was concentration-dependent (EC(50) 75 nM), rapid (maximum at 1 min) and transient. Phorbol ester-induced phosphorylation was concentration-dependent (EC(50) 25 nM), slightly slower (maximum at 5 min) and stable for at least 60 min. Inhibitors of protein kinase C decreased the effect of phorbol esters but not that of noradrenaline. Evidence of cross-talk of alpha(1d)-adrenoceptors with receptors endogenously expressed in rat-1 fibroblasts was given by the ability of endothelin, lysophosphatidic acid and bradykinin to induce alpha(1d)-adrenoceptor phosphorylation. In summary, it is shown for the first time here that alpha(1d)-adrenoceptors are phosphoproteins and that receptor phosphorylation is increased by the natural ligand, noradrenaline, by direct activation of protein kinase C and via cross-talk with other receptors endogenously expressed in rat-1 fibroblasts. Receptor phosphorylation has functional repercussions. PMID:11171057

  4. Novel alkoxy-oxazolyl-tetrahydropyridine muscarinic cholinergic receptor antagonists.

    PubMed

    Shannon, H E; Bymaster, F P; Hendrix, J C; Quimby, S J; Mitch, C H

    1995-01-01

    The purpose of the present studies was to compare a novel series of alkoxy-oxazolyl-tetrahydropyridines (A-OXTPs) as muscarinic receptor antagonists. The affinity of these compounds for muscarinic receptors was determined by inhibition of [3H]pirenzepine to M1 receptors in hippocampus, [3H]QNB to M2 receptors in brainstem, and [3H]oxotremorine-M to high affinity muscarinic agonist binding sites in cortex. All of the compounds had higher affinity for [3H]pirenzepine than for [3H]QNB or [3H]oxotremorine-M labeled receptors, consistent with an interpretation that they are relatively selective M1 receptor antagonists, although none were as selective as pirenzepine. In addition, dose-response curves were determined for antagonism of oxotremorine-induced salivation (mediated by M3 receptors) and tremor (mediated by non-M1 receptors) in mice. In general, the A-OXTPs were equipotent and equieffective in antagonizing both salivation and tremor, although there were modest differences for some compounds. Dose-response curves also were determined on behavior maintained under a spatial-alternation schedule of food presentation in rats as a measure of effects on working memory. The A-OXTPs produced dose-related decreases in percent correct responding at doses three- to ten-fold lower than those which decreased rates of responding. However, only one compound, MB-OXTP, produced effects on percent correct responding consistent with a selective effect on memory as opposed to non-memory variables. The present results provide evidence that these alkoxy-oxazolyl-tetrahydropyridines are a novel series of modestly M1-selective muscarinic receptor antagonists, and that one member of the series, MB-OXTP, appears to be more selective in its effects on memory than previously studies muscarinic antagonists. PMID:7753969

  5. Hypoxia increases exercise heart rate despite combined inhibition of β-adrenergic and muscarinic receptors.

    PubMed

    Siebenmann, C; Rasmussen, P; Sørensen, H; Bonne, T C; Zaar, M; Aachmann-Andersen, N J; Nordsborg, N B; Secher, N H; Lundby, C

    2015-06-15

    Hypoxia increases the heart rate response to exercise, but the mechanism(s) remains unclear. We tested the hypothesis that the tachycardic effect of hypoxia persists during separate, but not combined, inhibition of β-adrenergic and muscarinic receptors. Nine subjects performed incremental exercise to exhaustion in normoxia and hypoxia (fraction of inspired O2 = 12%) after intravenous administration of 1) no drugs (Cont), 2) propranolol (Prop), 3) glycopyrrolate (Glyc), or 4) Prop + Glyc. HR increased with exercise in all drug conditions (P < 0.001) but was always higher at a given workload in hypoxia than normoxia (P < 0.001). Averaged over all workloads, the difference between hypoxia and normoxia was 19.8 ± 13.8 beats/min during Cont and similar (17.2 ± 7.7 beats/min, P = 0.95) during Prop but smaller (P < 0.001) during Glyc and Prop + Glyc (9.8 ± 9.6 and 8.1 ± 7.6 beats/min, respectively). Cardiac output was enhanced by hypoxia (P < 0.002) to an extent that was similar between Cont, Glyc, and Prop + Glyc (2.3 ± 1.9, 1.7 ± 1.8, and 2.3 ± 1.2 l/min, respectively, P > 0.4) but larger during Prop (3.4 ± 1.6 l/min, P = 0.004). Our results demonstrate that the tachycardic effect of hypoxia during exercise partially relies on vagal withdrawal. Conversely, sympathoexcitation either does not contribute or increases heart rate through mechanisms other than β-adrenergic transmission. A potential candidate is α-adrenergic transmission, which could also explain why a tachycardic effect of hypoxia persists during combined β-adrenergic and muscarinic receptor inhibition. PMID:25888515

  6. Influence of the beta-adrenergic receptor concentration on functional coupling to the adenylate cyclase system.

    PubMed Central

    Severne, Y; Coppens, D; Bottari, S; Riviere, M; Kram, R; Vauquelin, G

    1984-01-01

    Only part of the beta-adrenergic receptors can undergo functional coupling to the adenylate cyclase regulatory unit. This receptor subpopulation shows an increased affinity for agonists in the presence of Mg2+ and undergoes rapid "inactivation" (locking-in of the agonist) by the alkylating reagent N-ethylmaleimide in the presence of agonists. Several experimental conditions, known to modify the total receptor concentration without alteration of the other components of the adenylate cyclase system, do not affect the percentage of receptors that can undergo functional coupling: (i) homologous regulation of beta 1 receptors in rat brain by noradrenaline (through antidepressive drug or reserpine injections); (ii) up- and down-regulation of the beta 2 receptors in Friend erythroleukemia cells by, respectively, sodium butyrate and cinnarizine treatment; and (iii) dithiothreitol-mediated inactivation of receptors in turkey erythrocytes, Friend erythroleukemia cells, and rat brain. Our findings argue against a stoichiometric limitation in the number of regulatory components, genetically different receptor subpopulations, bound guanine nucleotides, or reduced accessibility of part of the receptors to the agonists as the cause for functional receptor heterogeneity. Differences in either the receptor conformation or its membrane microenvironment are more plausible explanations. PMID:6087337

  7. Endothelin receptor antagonists as disease modifiers in systemic sclerosis.

    PubMed

    Shetty, Nagalakshmi; Derk, Chris T

    2011-02-01

    Systemic sclerosis (SSc) is a multisystem connective tissue disease of unknown etiology that is characterized by inflammation, vascular dysfunction and fibrosis of the skin and visceral organs. SSc is clinically diverse both in terms of the burden of skin and organ involvement and the rate of progression of the disease. Recent studies indicate that the endothelin system, especially ET-1 and the ETA and ETB receptors may play a key role in the pathogenesis of SSc. A new class of drugs, endothelin receptor antagonists has been introduced for treatment of patients with pulmonary arterial hypertension (PAH). Bosentan, a dual endothelin receptor antagonist as well as Sitaxsentan and Ambrisentan, selective blockers of the ETA receptor have proven effective in SSc-PAH. This effect may be mediated through both a vasodilatory and antifibrotic effect, thus making these agents attractive as potential disease modifying agents for SSc. PMID:21184655

  8. β-adrenergic receptor agonist, Compound 49b, inhibits TLR4 signaling pathway in diabetic retina

    PubMed Central

    Berger, Elizabeth A.; Carion, Thomas W.; Jiang, Youde; Liu, Li; Chahine, Adam; Walker, Robert Jason; Steinle, Jena J.

    2016-01-01

    Diabetic retinopathy has recently become associated with complications similar to chronic inflammatory diseases. While it is clear that tumor necrosis factor- alpha (TNF-α) is increased in diabetes, the role of innate immunity is only recently being investigated. As such, we hypothesized that diabetes would increase toll-like receptor 4 (TLR4) signaling, which could be inhibited by a β-adrenergic receptor agonist (Compound 49b) previously shown to have anti-inflammatory actions. In order to investigate β-adrenergic receptor signaling and TLR4 in the diabetic retina, streptozotocin-injected diabetic mice, as well as human primary retinal endothelial cells (REC) and rat retinal Müller cells (rMC-1) exposed to high glucose (25mM), were treated with a novel β-adrenergic receptor agonist, Compound 49b (50nM), or PBS (control). TLR4 and its downstream signaling partners (MyD88, IRAK1, TRAF6, total and phosphorylated NF-κB) were examined. In addition, we assessed high mobility box group 1 (HMGB1) protein levels. Our data showed that diabetes or high glucose culture conditions significantly increased TLR4 and downstream signaling partners. Compound 49b was able to significantly reduce TLR4 and related molecules in the diabetic animal and retinal cells. HMGB1 was significantly increased in REC and Müller cells grown in high glucose, which was subsequently reduced with Compound 49b treatment. Our findings suggest that high glucose may increase HMGB1 levels that lead to increased TLR4 signaling. Compound 49b significantly inhibited this pathway providing a potential mechanism for its protective actions. PMID:26888251

  9. 2-Cycloalkyl phenoxyacetic acid CRTh2 receptor antagonists.

    PubMed

    Sandham, David A; Aldcroft, Clive; Baettig, Urs; Barker, Lucy; Beer, David; Bhalay, Gurdip; Brown, Zarin; Dubois, Gerald; Budd, David; Bidlake, Louise; Campbell, Emma; Cox, Brian; Everatt, Brian; Harrison, David; Leblanc, Catherine J; Manini, Jodie; Profit, Rachael; Stringer, Rowan; Thompson, Katy S; Turner, Katharine L; Tweed, Morris F; Walker, Christoph; Watson, Simon J; Whitebread, Steven; Willis, Jennifer; Williams, Gareth; Wilson, Caroline

    2007-08-01

    High throughput screening identified a phenoxyacetic acid scaffold as a novel CRTh2 receptor antagonist chemotype, which could be optimised to furnish a compound with functional potency for inhibition of human eosinophil shape change and oral bioavailability in the rat. PMID:17531480

  10. Alterations in alpha-adrenergic and muscarinic cholinergic receptor binding in rat brain following nonionizing radiation

    SciTech Connect

    Gandhi, V.C.; Ross, D.H.

    1987-01-01

    Microwave radiation produces hyperthermia. The mammalian thermoregulatory system defends against changes in temperature by mobilizing diverse control mechanisms. Neurotransmitters play a major role in eliciting thermoregulatory responses. The involvement of adrenergic and muscarinic cholinergic receptors was investigated in radiation-induced hyperthermia. Rats were subjected to radiation at 700 MHz frequency and 15 mW/cm/sup 2/ power density and the body temperature was raised by 2.5 degrees C. Of six brain regions investigated only the hypothalamus showed significant changes in receptor states, confirming its pivotal role in thermoregulation. Adrenergic receptors, studied by (/sup 3/H)clonidine binding, showed a 36% decrease in binding following radiation after a 2.5 degrees C increase in body temperature, suggesting a mechanism to facilitate norepinephrine release. Norepinephrine may be speculated to maintain thermal homeostasis by activating heat dissipation. Muscarinic cholinergic receptors, studied by (3H)quinuclidinyl benzilate binding, showed a 65% increase in binding at the onset of radiation. This may be attributed to the release of acetylcholine in the hypothalamus in response to heat cumulation. The continued elevated binding during the period of cooling after radiation was shut off may suggest the existence of an extra-hypothalamic heat-loss pathway.

  11. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2016-09-01

    Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects. PMID:27108935

  12. Methylphenidate amplifies long-term potentiation in rat hippocampus CA1 area involving the insertion of AMPA receptors by activation of β-adrenergic and D1/D5 receptors.

    PubMed

    Rozas, C; Carvallo, C; Contreras, D; Carreño, M; Ugarte, G; Delgado, R; Zeise, M L; Morales, B

    2015-12-01

    Methylphenidate (MPH, Ritalin©) is widely used in the treatment of Attention Deficit Hyperactivity Disorder and recently as a drug of abuse. Although the effect of MPH has been studied in brain regions such as striatum and prefrontal cortex (PFC), the hippocampus has received relatively little attention. It is known that MPH increases the TBS-dependent Long Term Potentiation (LTP) in the CA1 area. However, the cellular and molecular mechanisms involved in this process are still unknown. Using field potential recordings and western blot analysis in rat hippocampal slices of young rats, we found that acute application of MPH enhances LTP in CA3-CA1 synapses in a dose-dependent manner with an EC50 of 73.44±6.32 nM. Using specific antagonists and paired-pulse facilitation protocols, we observed that the MPH-dependent increase of LTP involves not only β-adrenergic receptors activation but also post-synaptic D1/D5 dopamine receptors. The inhibition of PKA with PKI, suppressed the facilitation of LTP induced by MPH consistent with an involvement of the adenyl cyclase-cAMP-PKA dependent cascade downstream of the activation of D1/D5 receptors. In addition, samples of CA1 areas taken from slices potentiated with MPH presented an increase in the phosphorylation of the Ser845 residue of the GluA1 subunit of AMPA receptors compared to control slices. This effect was reverted by SCH23390, antagonist of D1/D5 receptors, and PKI. Moreover, we found an increase of surface-associated functional AMPA receptors. We propose that MPH increases TBS-dependent LTP in CA3-CA1 synapses through a polysynaptic mechanism involving activation of β-adrenergic and D1/D5 dopaminergic receptors and promoting the trafficking and insertion of functional AMPA receptors to the plasma membrane. PMID:26165920

  13. Effects of Adrenergic Receptor Activation and Blockade on the Systolic Preejection Period, Heart Rate, and Arterial Pressure in Man

    PubMed Central

    Harris, Willard S.; Schoenfeld, Clyde D.; Weissler, Arnold M.

    1967-01-01

    We have investigated the possibility that alterations in the duration of the systolic preejection period can be used to estimate adrenergic influences on the human left ventricle. The preejection period was determined from high speed, simultaneous recordings of the phonocardiogram, carotid pulse tracing, and electrocardiogram. The preejection period was shortened by isoproterenol, epinephrine, and moderate doses of norepinephrine—all of which activate beta adrenergic receptors—and by cedilanid-D. It was unaltered by changes in heart rate induced by atropine and right atrial electrical pacing. Beta adrenergic receptor blockade by propranolol abolished the shortening effects of the three catecholamines but did not inhibit that due to cedilanid-D. Vasoconstriction, both alpha adrenergic (epinephrine and norepinephrine after propranolol) and nonadrenergic (angiotensin), prolonged the preejection period. Most of the shortening of the preejection period by beta adrenergic receptor activating agents and cedilanid-D and all of the prolongation accompanying pharmacologic vasoconstriction occurred after the onset of the first heart sound, thereby excluding changes in electrical-mechanical delay as a major factor in the observed preejection period responses. Shortening of the preejection period by beta adrenergic activity induced with isoproterenol was dose-related. Increasing doses of propranolol produced parallel shifts to the right in the isoproterenol dose-response curve. In 37 normal resting subjects intravenous propranolol (10 mg) prolonged the preejection period an average of 10 (SE ± 1) msec. In six patients with psychogenic sinus tachycardia and a patient with a pheochromocytoma the presence of excessive beta adrenergic influences on the left ventricle was demonstrated by the finding of an initially short preejection period which responded with an abnormally great prolongation to beta adrenergic receptor blockade. Images PMID:4294053

  14. In Vitro Mutational Analysis of the β2 Adrenergic Receptor, an In Vivo Surrogate Odorant Receptor

    PubMed Central

    Pfister, Patrick; Tomoiaga, Delia; Rogers, Matthew E.; Feinstein, Paul

    2015-01-01

    Many G-protein coupled receptors (GPCRs), such as odorant receptors (ORs), cannot be characterized in heterologous cells because of their difficulty in trafficking to the plasma membrane. In contrast, a surrogate OR, the GPCR mouse β2-adrenergic-receptor (mβ2AR), robustly traffics to the plasma membrane. We set out to characterize mβ2AR mutants in vitro for their eventual use in olfactory axon guidance studies. We performed an extensive mutational analysis of mβ2AR using a Green Fluorescent Protein-tagged mβ2AR (mβ2AR::GFP) to easily assess the extent of its plasma membrane localization. In order to characterize mutants for their ability to successfully transduce ligand-initiated signal cascades, we determined the half maximal effective concentrations (EC50) and maximal response to isoprenaline, a known mβ2AR agonist. Our analysis reveals that removal of amino terminal (Nt) N-glycosylation sites and the carboxy terminal (Ct) palmitoylation site of mβ2AR do not affect its plasma membrane localization. By contrast, when both the Nt and Ct of mβ2AR are replaced with those of M71 OR, plasma membrane trafficking is impaired. We further analyze three mβ2AR mutants (RDY, E268A, and C327R) used in olfactory axon guidance studies and are able to decorrelate their plasma membrane trafficking with their capacity to respond to isoprenaline. A deletion of the Ct prevents proper trafficking and abolishes activity, but plasma membrane trafficking can be selectively rescued by a Tyrosine to Alanine mutation in the highly conserved GPCR motif NPxxY. This new loss-of-function mutant argues for a model in which residues located at the end of transmembrane domain 7 can act as a retention signal when unmasked. Additionally, to our surprise, amongst our set of mutations only Ct mutations appear to lower mβ2AR EC50s revealing their critical role in G-protein coupling. We propose that an interaction between the Nt and Ct is necessary for proper folding and/or transport of GPCRs

  15. In Vitro Mutational Analysis of the β2 Adrenergic Receptor, an In Vivo Surrogate Odorant Receptor.

    PubMed

    Jamet, Sophie; Bubnell, Jaclyn; Pfister, Patrick; Tomoiaga, Delia; Rogers, Matthew E; Feinstein, Paul

    2015-01-01

    Many G-protein coupled receptors (GPCRs), such as odorant receptors (ORs), cannot be characterized in heterologous cells because of their difficulty in trafficking to the plasma membrane. In contrast, a surrogate OR, the GPCR mouse β2-adrenergic-receptor (mβ2AR), robustly traffics to the plasma membrane. We set out to characterize mβ2AR mutants in vitro for their eventual use in olfactory axon guidance studies. We performed an extensive mutational analysis of mβ2AR using a Green Fluorescent Protein-tagged mβ2AR (mβ2AR::GFP) to easily assess the extent of its plasma membrane localization. In order to characterize mutants for their ability to successfully transduce ligand-initiated signal cascades, we determined the half maximal effective concentrations (EC50) and maximal response to isoprenaline, a known mβ2AR agonist. Our analysis reveals that removal of amino terminal (Nt) N-glycosylation sites and the carboxy terminal (Ct) palmitoylation site of mβ2AR do not affect its plasma membrane localization. By contrast, when both the Nt and Ct of mβ2AR are replaced with those of M71 OR, plasma membrane trafficking is impaired. We further analyze three mβ2AR mutants (RDY, E268A, and C327R) used in olfactory axon guidance studies and are able to decorrelate their plasma membrane trafficking with their capacity to respond to isoprenaline. A deletion of the Ct prevents proper trafficking and abolishes activity, but plasma membrane trafficking can be selectively rescued by a Tyrosine to Alanine mutation in the highly conserved GPCR motif NPxxY. This new loss-of-function mutant argues for a model in which residues located at the end of transmembrane domain 7 can act as a retention signal when unmasked. Additionally, to our surprise, amongst our set of mutations only Ct mutations appear to lower mβ2AR EC50s revealing their critical role in G-protein coupling. We propose that an interaction between the Nt and Ct is necessary for proper folding and/or transport of GPCRs

  16. Use of the H3 receptor antagonist radioligand [3H]-A-349821 to reveal in vivo receptor occupancy of cognition enhancing H3 receptor antagonists

    PubMed Central

    Miller, TR; Milicic, I; Bauch, J; Du, J; Surber, B; Browman, KE; Marsh, K; Cowart, M; Brioni, JD; Esbenshade, TA

    2009-01-01

    Background and purpose: The histamine H3 receptor antagonist radioligand [3H]-A-349821 was characterized as a radiotracer for assessing in vivo receptor occupancy by H3 receptor antagonists that affect behaviour. This model was established as an alternative to ex vivo binding methods, for relating antagonist H3 receptor occupancy to blood levels and efficacy in preclinical models. Experimental approach: In vivo cerebral cortical H3 receptor occupancy by [3H]-A-349821 was determined in rats from differences in [3H]-A-349821 levels in the isolated cortex and cerebellum, a brain region with low levels of H3 receptors. Comparisons were made to relate antagonist H3 receptor occupancy to blood levels and efficacy in a preclinical model of cognition, the five-trial inhibitory avoidance response in rat pups. Key results: In adult rats, [3H]-A-349821, 1.5 µg·kg−1, penetrated into the brain and cleared more rapidly from cerebellum than cortex; optimally, [3H]-A-349821 levels were twofold higher in the latter. With increasing [3H]-A-349821 doses, cortical H3 receptor occupancy was saturable with a binding capacity consistent with in vitro binding in cortex membranes. In studies using tracer [3H]-A-349821 doses, ABT-239 and other H3 receptor antagonists inhibited H3 receptor occupancy by [3H]-A-349821 in a dose-dependent manner. Blood levels of the antagonists corresponding to H3 receptor occupancy were consistent with blood levels associated with efficacy in the five-trial inhibitory avoidance response. Conclusions and implications: When employed as an occupancy radiotracer, [3H]-A-349821 provided valid measurements of in vivo H3 receptor occupancy, which may be helpful in guiding and interpreting clinical studies of H3 receptor antagonists. PMID:19413577

  17. DEVELOPMENT OF SEROTONERGIC AND ADRENERGIC RECEPTORS IN THE RAT SPINAL CORD: EFFECTS OF NEONATAL CHEMICAL LESIONS AND HYPERTHYROIDISM

    EPA Science Inventory

    The ontogeny of serotonergic receptors and alpha- and beta-adrenergic receptors in thoracolumbar spinal cord of rats given neurotoxins which destroy serotonergic (5,7-dihydroxytryptamine (5,7-DHT) or noradrenergic (6-hydroxydopamine (6-OHDA)) nerve terminals was examined. Intraci...

  18. Regulation of cardiac nitric oxide signaling by nuclear β-adrenergic and endothelin receptors*

    PubMed Central

    Vaniotis, George; Glazkova, Irina; Merlen, Clémence; Smith, Carter; Villeneuve, Louis R.; Chatenet, David; Therien, Michel; Fournier, Alain; Tadevosyan, Artavazd; Trieu, Phan; Nattel, Stanley; Hébert, Terence E.; Allen, Bruce G.

    2013-01-01

    At the cell surface, βARs and endothelin receptors can regulate nitric oxide (NO) production. β-adrenergic receptors (βARs) and type B endothelin receptors (ETB) are present in cardiac nuclear membranes and regulate transcription. The present study investigated the role of the NO pathway in the regulation of gene transcription by these nuclear G protein-coupled receptors. Nitric oxide production and transcription initiation were measured in nuclei isolated from adult rat heart. The cell-permeable fluorescent dye 4,5-diaminofluorescein diacetate (DAF2 DA) was used to provide a direct assessment of nitric oxide release. Both isoproterenol and endothelin increased NO production in isolated nuclei. Furthermore, a β3AR-selective agonist, BRL 37344, increased NO synthesis whereas the β1AR-selective agonist xamoterol did not. Isoproterenol increased, whereas ET-1 reduced, de novo transcription. The NO synthase inhibitor L-NAME prevented isoproterenol from increasing either NO production or de novo transcription. L-NAME also blocked ET-1-induced NO-production but did not alter the suppression of transcription initiation by ET-1. Inhibition of the cGMP-dependent protein kinase (PKG) using KT5823 also blocked the ability of isoproterenol to increase transcription initiation. Furthermore, immunoblotting revealed eNOS, but not nNOS, in isolated nuclei. Finally, caged, cell-permeable isoproterenol and endothelin-1 analogs were used to selectively activate intracellular β-adrenergic and endothelin receptors in intact adult cardiomyocytes. Intracellular release of caged ET-1 or isoproterenol analogs increased NO production in intact adult cardiomyocytes. Hence, activation of the NO synthase/guanylyl cyclase/PKG pathway is necessary for nuclear β3ARs to increase de novo transcription. Furthermore, we have demonstrated the potential utility of caged receptor ligands in selectively modulating signaling via endogenous intracellular G protein-coupled receptors. PMID:23684854

  19. Stress-induced sensitization of cortical adrenergic receptors following a history of cannabinoid exposure

    PubMed Central

    Reyes, B.A.S.; Szot, P.; Sikkema, C.; Cathel, A. M.; Kirby, L.G.; Van Bockstaele, E.J.

    2014-01-01

    The cannabinoid receptor agonist, WIN 55,212-2, increases extracellular norepinephrine levels in the rat frontal cortex under basal conditions, likely via desensitization of inhibitory α2-adrenergic receptors located on norepinephrine terminals. Here, the effect of WIN 55,212-2 on stress-induced norepinephrine release was assessed in the medial prefrontal cortex (mPFC), in adult male Sprague-Dawley rats using in vivo microdialysis. Systemic administration of WIN 55,212-2 thirty minutes prior to stressor exposure prevented stress-induced cortical norepinephrine release induced by a single exposure to swim when compared to vehicle. To further probe cortical cannabinoid-adrenergic interactions, postsynaptic α2-adrenergic receptor (AR)-mediated responses were assessed in mPFC pyramidal neurons using electrophysiological analysis in an in vitro cortical slice preparation. We confirm prior studies showing that clonidine increases cortical pyramidal cell excitability and that this was unaffected by exposure to acute stress. WIN 55,212-2, via bath application, blocked postsynaptic α2-AR mediated responses in cortical neurons irrespective of exposure to stress. Interestingly, stress exposure prevented the desensitization of α2-AR mediated responses produced by a history of cannabinoid exposure. Together, these data indicate the stress-dependent nature of cannabinoid interactions via both pre- and postsynaptic ARs. In summary, microdialysis data indicate that cannabinoids restrain stress-induced cortical NE efflux. Electrophysiology data indicate that cannabinoids also restrain cortical cell excitability under basal conditions; however, stress interferes with these CB1-α2 AR interactions, potentially contributing to over-activation of pyramidal neurons in mPFC. Overall, cannabinoids are protective of the NE system and cortical excitability but stress can derail this protective effect, potentially contributing to stress-related psychopathology. These data add to the

  20. Extra-helical binding site of a glucagon receptor antagonist.

    PubMed

    Jazayeri, Ali; Doré, Andrew S; Lamb, Daniel; Krishnamurthy, Harini; Southall, Stacey M; Baig, Asma H; Bortolato, Andrea; Koglin, Markus; Robertson, Nathan J; Errey, James C; Andrews, Stephen P; Teobald, Iryna; Brown, Alastair J H; Cooke, Robert M; Weir, Malcolm; Marshall, Fiona H

    2016-05-12

    Glucagon is a 29-amino-acid peptide released from the α-cells of the islet of Langerhans, which has a key role in glucose homeostasis. Glucagon action is transduced by the class B G-protein-coupled glucagon receptor (GCGR), which is located on liver, kidney, intestinal smooth muscle, brain, adipose tissue, heart and pancreas cells, and this receptor has been considered an important drug target in the treatment of diabetes. Administration of recently identified small-molecule GCGR antagonists in patients with type 2 diabetes results in a substantial reduction of fasting and postprandial glucose concentrations. Although an X-ray structure of the transmembrane domain of the GCGR has previously been solved, the ligand (NNC0640) was not resolved. Here we report the 2.5 Å structure of human GCGR in complex with the antagonist MK-0893 (ref. 4), which is found to bind to an allosteric site outside the seven transmembrane (7TM) helical bundle in a position between TM6 and TM7 extending into the lipid bilayer. Mutagenesis of key residues identified in the X-ray structure confirms their role in the binding of MK-0893 to the receptor. The unexpected position of the binding site for MK-0893, which is structurally similar to other GCGR antagonists, suggests that glucagon activation of the receptor is prevented by restriction of the outward helical movement of TM6 required for G-protein coupling. Structural knowledge of class B receptors is limited, with only one other ligand-binding site defined--for the corticotropin-releasing hormone receptor 1 (CRF1R)--which was located deep within the 7TM bundle. We describe a completely novel allosteric binding site for class B receptors, providing an opportunity for structure-based drug design for this receptor class and furthering our understanding of the mechanisms of activation of these receptors. PMID:27111510

  1. Label-free integrative pharmacology on-target of drugs at the β2-adrenergic receptor

    NASA Astrophysics Data System (ADS)

    Ferrie, Ann M.; Sun, Haiyan; Fang, Ye

    2011-07-01

    We describe a label-free integrative pharmacology on-target (iPOT) method to assess the pharmacology of drugs at the β2-adrenergic receptor. This method combines dynamic mass redistribution (DMR) assays using an array of probe molecule-hijacked cells with similarity analysis. The whole cell DMR assays track cell system-based, ligand-directed, and kinetics-dependent biased activities of the drugs, and translates their on-target pharmacology into numerical descriptors which are subject to similarity analysis. We demonstrate that the approach establishes an effective link between the label-free pharmacology and in vivo therapeutic indications of drugs.

  2. Housing temperature-induced stress drives therapeutic resistance in murine tumour models through β2-adrenergic receptor activation

    NASA Astrophysics Data System (ADS)

    Eng, Jason W.-L.; Reed, Chelsey B.; Kokolus, Kathleen M.; Pitoniak, Rosemarie; Utley, Adam; Bucsek, Mark J.; Ma, Wen Wee; Repasky, Elizabeth A.; Hylander, Bonnie L.

    2015-03-01

    Cancer research relies heavily on murine models for evaluating the anti-tumour efficacy of therapies. Here we show that the sensitivity of several pancreatic tumour models to cytotoxic therapies is significantly increased when mice are housed at a thermoneutral ambient temperature of 30 °C compared with the standard temperature of 22 °C. Further, we find that baseline levels of norepinephrine as well as the levels of several anti-apoptotic molecules are elevated in tumours from mice housed at 22 °C. The sensitivity of tumours to cytotoxic therapies is also enhanced by administering a β-adrenergic receptor antagonist to mice housed at 22 °C. These data demonstrate that standard housing causes a degree of cold stress sufficient to impact the signalling pathways related to tumour-cell survival and affect the outcome of pre-clinical experiments. Furthermore, these data highlight the significant role of host physiological factors in regulating the sensitivity of tumours to therapy.

  3. Housing temperature-induced stress drives therapeutic resistance in murine tumour models through β2-adrenergic receptor activation

    PubMed Central

    Eng, Jason W.-L.; Reed, Chelsey B.; Kokolus, Kathleen M.; Pitoniak, Rosemarie; Utley, Adam; Bucsek, Mark J.; Ma, Wen Wee; Repasky, Elizabeth A.; Hylander, Bonnie L.

    2015-01-01

    Cancer research relies heavily on murine models for evaluating the anti-tumour efficacy of therapies. Here we show that the sensitivity of several pancreatic tumour models to cytotoxic therapies is significantly increased when mice are housed at a thermoneutral ambient temperature of 30 °C compared with the standard temperature of 22 °C. Further, we find that baseline levels of norepinephrine as well as the levels of several anti-apoptotic molecules are elevated in tumours from mice housed at 22 °C. The sensitivity of tumours to cytotoxic therapies is also enhanced by administering a β-adrenergic receptor antagonist to mice housed at 22 °C. These data demonstrate that standard housing causes a degree of cold stress sufficient to impact the signalling pathways related to tumour-cell survival and affect the outcome of pre-clinical experiments. Furthermore, these data highlight the significant role of host physiological factors in regulating the sensitivity of tumours to therapy. PMID:25756236

  4. Propafenone interacts stereoselectively with beta 1- and beta 2-adrenergic receptors

    SciTech Connect

    Burnett, D.M.; Gal, J.; Zahniser, N.R.; Nies, A.S.

    1988-01-01

    In order to determine whether the new antiarrhythmic agent propafenone interacts stereoselectively with beta-adrenergic receptors, the potencies of both the (-) and (+) isomers were determined using in vitro binding assays. (-)-Propafenone was the more potent isomer and competed with /sup 125/I-pindolol in a simple manner in both rat cerebral cortical and cerebellar membranes with Ki values of 32 +/- 1.7 and 77 +/- 5.8 nM, respectively. In contrast, competition curves for (+)-propafenone in the same tissues were more complex and revealed two binding sites with affinities 10- to 75-fold less potent than those for (-)-propafenone. Moreover, the (+)-propafenone was found by high performance liquid chromatography (HPLC) analysis to be contaminated with 3% of the more potent (-)-isomer; this contamination accounted for most of the apparent activity of the (+)-propafenone. These data suggest that interactions of propafenone with both beta 1- and beta 2-receptors are markedly stereoselective for the (-) isomer. It is possible that beta-adrenergic receptor blockade by the (-) isomer may be responsible for some of the adverse clinical effects that have been reported with propafenone therapy.

  5. β(1) Adrenergic receptor is key to cold- and diet-induced thermogenesis in mice.

    PubMed

    Ueta, Cintia B; Fernandes, Gustavo W; Capelo, Luciane P; Fonseca, Tatiane L; Maculan, Flávia D'Angelo; Gouveia, Cecilia H A; Brum, Patrícia C; Christoffolete, Marcelo A; Aoki, Marcelo S; Lancellotti, Carmen L; Kim, Brian; Bianco, Antonio C; Ribeiro, Miriam O

    2012-09-01

    Brown adipose tissue (BAT) is predominantly regulated by the sympathetic nervous system (SNS) and the adrenergic receptor signaling pathway. Knowing that a mouse with triple β-receptor knockout (KO) is cold intolerant and obese, we evaluated the independent role played by the β(1) isoform in energy homeostasis. First, the 30  min i.v. infusion of norepinephrine (NE) or the β(1) selective agonist dobutamine (DB) resulted in similar interscapular BAT (iBAT) thermal response in WT mice. Secondly, mice with targeted disruption of the β(1) gene (KO of β(1) adrenergic receptor (β(1)KO)) developed hypothermia during cold exposure and exhibited decreased iBAT thermal response to NE or DB infusion. Thirdly, when placed on a high-fat diet (HFD; 40% fat) for 5 weeks, β(1)KO mice were more susceptible to obesity than WT controls and failed to develop diet-induced thermogenesis as assessed by BAT Ucp1 mRNA levels and oxygen consumption. Furthermore, β(1)KO mice exhibited fasting hyperglycemia and more intense glucose intolerance, hypercholesterolemia, and hypertriglyceridemia when placed on the HFD, developing marked non-alcoholic steatohepatitis. In conclusion, the β(1) signaling pathway mediates most of the SNS stimulation of adaptive thermogenesis. PMID:22728333

  6. Influence of Panax ginseng on Alpha-Adrenergic Receptor of Benign Prostatic Hyperplasia

    PubMed Central

    Kim, Su Kang; Chung, Joo-Ho; Lee, Byung-Cheol; Lee, Sang Won; Lee, Kang Hyo

    2014-01-01

    Purpose Benign prostatic hyperplasia (BPH) is the most common prostate problem in older men. The present study aimed to investigate the inhibitory effect of Panax ginseng C.A. Meyer (P. ginseng) on a rat model of testosterone-induced BPH. Methods The rats were divided into 3 groups (each group, n=10): control, testosterone-induced BPH (20 mg/kg, subcutaneous injection), and P. ginseng (200 mg/kg, orally) groups. After 4 weeks, all animals were sacrificed to examine the blood biochemical profiles, prostate volume, weight, histopathological changes, alpha-1D adrenergic receptor (Adra1d) mRNA expression, and epidermal growth factor receptor (EGFR) and B-cell CLL/lymphoma 2 (BCL2) protein expression. Results The group treated with P. ginseng showed significantly lesser prostate size and weight than the testosterone-induced BPH group. In addition, P. ginseng decreased the mRNA expression of Adra1d as well as the expression of EGFR and BCL2 in prostate tissue. Conclusions These results suggest that P. ginseng may inhibit the alpha-1-adrenergic receptor to suppress the development of BPH. PMID:25558416

  7. Variability in Beta-Adrenergic Receptor Population in Cultured Chicken Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, Ronald B; Bridge, Kristin Y.; Vaughn, Jeffrey R.

    1998-01-01

    Investigations into expression of the beta-adrenergic receptor (bAR) in chicken skeletal muscle cells in culture were initiated because several beta-adrenergic receptor agonists are known to increase skeletal muscle protein deposition in avian and mammalian species. During initial attempts to study the bAR population on the surface of chicken skeletal muscle cells, we observed a high degree of variability that was later found to be the result of using different batches of horse serum in the cell culture media. The separation between total binding and nonspecific binding in cells grown in two serum samples was approximately two-fold The number of nuclei within multinucleated myotubes was not significantly different in cells grown in the two serum samples. To investigate whether these two sera had an effect on coupling efficiency between bAR population and cAMP production, the ability of these cells to synthesize cAMP was also assessed. Despite the two-fold difference in receptor population, the ability of these cells to synthesize cAMP was not significantly different. Because of the possible link between bAR population and muscle protein, we also determined if the quantity of the major skeletal muscle protein, myosin, was affected by conditions that so drastically affected the bAR population. The quantity of myosin heavy chain was not significantly different.

  8. Electrical Stimulation Decreases Coupling Efficiency Between Beta-Adrenergic Receptors and Cyclic AMP Production in Cultured Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.

    1999-01-01

    Electrical stimulation of skeletal muscle cells in culture is an effective way to simulate the effects of muscle contraction and its effects on gene expression in muscle cells. Expression of the beta-adrenergic receptor and its coupling to cyclic AMP synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this project was to determine if electrical stimulation altered the beta-adrenergic response in muscle cells. Chicken skeletal muscle cells that had been grown for seven days in culture were subjected to electrical stimulation for an additional two days at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. At the end of this two-day stimulation period, beta-adrenergic receptor population was measured by the binding of tritium-labeled CGP-12177 to muscle cells, and coupling to cAMP synthesis was measured by Radioimmunoassay (RIA) after treating the cells for 10 min with the potent (beta)AR agonist, isoproterenol. The number of beta adrenergic receptors and the basal levels of intracellular cyclic AMP were not affected by electrical stimulation. However, the ability of these cells to synthesize cyclic AMP was reduced by approximately 50%. Thus, an enhanced level of contraction reduces the coupling efficiency of beta-adrenergic receptors for cyclic AMP production.

  9. Indirect immunofluorescence localization of beta-adrenergic receptors and G-proteins in human A431 cells.

    PubMed Central

    Wang, H Y; Berrios, M; Malbon, C C

    1989-01-01

    Polyclonal antibodies directed against (i) rodent lung beta 2-adrenergic receptor, (ii) a synthetic fragment of an extracellular domain of the receptor, and (iii) human placenta G-protein beta-subunits, were used to localize these antigens in situ in intact and permeabilized human epidermoid carcinoma A431 cells. Antibodies directed against beta 2-adrenergic receptors showed a punctate immunofluorescence staining throughout the cell surface of fixed intact cells. Punctate staining was also observed in clones of Chinese hamster ovary cells transfected with an expression vector harbouring the gene for the hamster beta 2-adrenergic receptor. The immunofluorescence observed with anti-receptor antibodies paralleled the level of receptor expression. In contrast, the beta-subunits common to G-proteins were not stained in fixed intact cells, presumably reflecting their intracellular localization. In detergent-permeabilized fixed cells, strong punctate staining of G beta-subunits was observed throughout the cytoplasm. This is the first indirect immunofluorescence localization of beta-adrenergic receptors and G-proteins. Punctate immunofluorescence staining suggests that both antigens are distributed in clusters. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. p528-a Fig. 9. Fig. 10. PMID:2556996

  10. Role of Central β-Adrenergic Receptors in Regulating Proinflammatory Cytokine Responses to a Peripheral Bacterial Challenge

    PubMed Central

    Johnson, John D.; Cortez, Valerie; Kennedy, Sarah L.; Foley, Teresa E.; Hanson, Hugo; Fleshner, Monika

    2008-01-01

    Elevation of proinflammatory cytokines in the brain have potent effects on altering physiological, behavioral, and cognitive processes. The mechanism(s) by which brain cytokines are induced during a peripheral immune challenge remains unclear since microorganisms/cytokines do not cross the blood-brain barrier (BBB). Recent studies indicate that central β-adrenergic receptors (β-ADRs) may mediate brain interleukin-1beta (IL-1) production. This has direct implications for the production of brain cytokines during a peripheral immune response since peripheral pathogens and cytokines rapidly stimulate brainstem catecholamine neurons via peripheral nerves and circumventricular pathways. Studies here examine the role of central β-ADRs in regulating brain cytokine production following peripheral Escherichia coli (E.coli) challenge. Rats were centrally administered propranolol (β-ADR antagonist) or vehicle followed by peripheral E.coli or saline and sacrificed 6h later for measurement of cytokines. Pretreatment with propranolol completely blocked the induction of brain IL-1 following E.coli. Surprisingly, central propranolol also attenuated E.coli-induced peripheral cytokines. To examine whether the attenuated peripheral cytokine response following central propranolol administration was due leakage of propranolol into the general circulation and blockade of peripheral β-blockade, nadolol (β-ADR antagonist that does not cross the BBB) was administered peripherally prior to E.coli. Nadolol administration did not block central cytokine production following E.coli, but instead enhanced both peripheral and central proinflammatory cytokine production. Furthermore, central administration of isoproterenol (β-ADR agonist) results in a time-dependent increase in brain IL-1 production. These data demonstrate central β-ADRs may play a critical role to induce brain IL-1, while peripheral β-ADRs inhibit cytokine response to bacterial challenge. PMID:18468841

  11. The Alpha-1D Is the Predominant Alpha-1-Adrenergic Receptor Subtype in Human Epicardial Coronary Arteries

    PubMed Central

    Jensen, Brian C.; Swigart, Philip M.; Laden, Marie-Eve; DeMarco, Teresa; Hoopes, Charles; Simpson, Paul C.

    2009-01-01

    Objectives The goal was to identify alpha-1-adrenergic receptor (α1-AR) subtypes in human coronary arteries. Background The α1-ARs regulate human coronary blood flow. α1-ARs exist as three molecular subtypes, α1A, α1B, and α1D, and the α1D subtype mediates coronary vasoconstriction in the mouse. However, the α1A is thought to be the only subtype in human coronary arteries. Methods We obtained human epicardial coronary arteries and left ventricular (LV) myocardium from 19 transplant recipients and 6 unused donors (age 19–70 years; 68% male; 32% with coronary artery disease). We cultured coronary rings and human coronary smooth muscle cells. We assayed α1- and β-AR subtype mRNAs by quantitative real-time reverse transcription PCR; and subtype proteins, by radioligand binding and ERK activation. Results The α1D subtype was 85% of total coronary α1-AR mRNA and 75% of total α1-AR protein, and α1D stimulation activated ERK. In contrast, the α1D was low in LV myocardium. Total coronary α1-AR levels were one-third of β-ARs, which were 99% the β2 subtype. Conclusions The α1D subtype is predominant and functional in human epicardial coronary arteries, whereas the α1A and α1B are present at very low levels. This distribution is similar to the mouse, where myocardial α1A and α1B-ARs mediate beneficial functional responses, and coronary α1Ds mediate vasoconstriction. Thus, α1D-selective antagonists might mediate coronary vasodilation, without the negative cardiac effects of non-selective α1-AR antagonists in current use. Furthermore, it could be possible to selectively activate beneficial myocardial α1A and/or α1B-AR signaling without causing coronary vasoconstriction. PMID:19761933

  12. The Roles of Dopamine and α1-Adrenergic Receptors in Cocaine Preferences in Female and Male Rats.

    PubMed

    Perry, Adam N; Westenbroek, Christel; Jagannathan, Lakshmikripa; Becker, Jill B

    2015-11-01

    Cocaine dependence is characterized by compulsive drug taking and reduced involvement in social, occupational, or recreational activities. Unraveling the diverse mechanisms contributing to the loss-of-interest in these 'non-drug' pursuits is essential for understanding the neurobiology of addiction and could provide additional targets for treating addiction. The study objectives were to examine changes in cocaine-induced dopamine (DA) overflow in the nucleus accumbens (NAc) over the course of self-administration and determine the roles of α1- and β-adrenergic receptors (AR) in the loss-of-interest in food rewards following the development of an addicted phenotype in male and female rats. Subjects were given access to cocaine and palatable food pellets in a choice self-administration paradigm to identify 'addicted' cocaine-preferring (CP) individuals and resistant pellet-preferring (PP) individuals based on their patterns of self-administration over 7 weeks. Cocaine-induced DA overflow in the NAc was examined with microdialysis early and late during self-administration (weeks 2 and 7). Subjects were treated in counter-balanced order with propranolol (β-AR antagonist), terazosin (α1-AR antagonist), or vehicle for an additional 3 weeks of self-administration. CP rats displayed increased motivation for cocaine and attenuated motivation for pellets following the development of cocaine preferences. In females, the estrous cycle affected pellet, but not cocaine, self-administration. CP rats displayed attenuated cocaine-induced DA overflow in the NAc. Propranolol enhanced cocaine reinforcement and reduced pellet intake, whereas terazosin enhanced motivation for pellets and reversed preferences in a subset of CP rats. The implications of these results for the treatment of addiction are discussed. PMID:25900120

  13. Transient receptor potential ankyrin 1 (TRPA1) antagonists.

    PubMed

    Preti, Delia; Saponaro, Giulia; Szallasi, Arpad

    2015-01-01

    The transient receptor potential ankyrin 1 (TRPA1) channel is an irritant sensor highly expressed on nociceptive neurons. The clinical use of TRPA1 antagonists is based on the concept that TRPA1 is active during disease states like neuropathic pain. Indeed, in Phase 2a proof-of-concept studies the TRPA1 antagonist GRC17536 has shown efficacy in patients with painful diabetic neuropathy. Moreover, animal studies suggest that the therapeutic value of TRPA1 antagonists extends beyond pain to pruritus, asthma and cough with limited safety concerns. This review provides a comprehensive overview of the patent literature (since 2007) on small-molecule inhibitors of the TRPA1 channel. Despite the clear progress, many unanswered questions remain. Future advancement to Phase 3 studies will assess the real translational potential of this research field. PMID:25853468

  14. μ Opioid receptor: novel antagonists and structural modeling

    NASA Astrophysics Data System (ADS)

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-02-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.

  15. μ Opioid receptor: novel antagonists and structural modeling

    PubMed Central

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-01-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates. PMID:26888328

  16. Modulation of non-adrenergic, non-cholinergic neural bronchoconstriction in guinea-pig airways via GABAB-receptors.

    PubMed

    Belvisi, M G; Ichinose, M; Barnes, P J

    1989-08-01

    1. Evidence suggests that gamma-aminobutyric acid (GABA) and its receptors are present in the peripheral nervous system. We have now investigated the effect of GABA and related substances on non-adrenergic, non-cholinergic (NANC) neurally-evoked bronchoconstriction in the anaesthetised guinea-pig. 2. Bilateral vagal stimulation (5 V, 5 ms, 3 or 5 Hz) for 30 s, after propranolol (1 mg kg-1 i.v.) and atropine (1 mg kg-1 i.v.) evoked a NANC bronchoconstrictor response manifest as a mean tracheal pressure rise of 21.9 +/- 1.04 cmH2O (n = 70). The bronchoconstrictor response was reproducible for any given animal. 3. GABA (10 micrograms-10 mg kg-1 i.v.) did not alter basal tracheal pressure but reduced the NANC bronchoconstrictor response to vagal stimulation in a dose-dependent manner (ED50 = 186 micrograms kg-1 with a maximal inhibition of 74 +/- 3.4% at 10 mg kg-1). Neither the opioid antagonist naloxone (1 mg kg-1 i.v.) nor the alpha-adrenoceptor antagonist phentolamine (2.5 mg kg-1 i.v.) had any significant effect on the inhibitory response produced by GABA (500 micrograms kg-1). 4. GABA-induced inhibition was not antagonised by the GABAA-antagonist bicuculline (2 mg kg-1 i.v.). 5. The GABAB-agonist baclofen (10 micrograms-3 mg kg-1 i.v.) caused a dose-dependent inhibition of the NANC response (ED50 = 100 micrograms kg-1 with a maximal inhibition of 35.5 +/- 2.8% at 3 mg kg-1). The GABAA-agonist, 4,5,6,7-tetrahydroisoxazolo[5,4-C] pyridin-3-ol (THIP), also inhibited the NANC bronchoconstrictor response. However, the dose of THIP required for this effect was high (3 mg kg- ') and the effect ( <10% inhibition) was small. 6. Substance P (SP; 5upgkg-1 or 25pgkg-1), produced a bronchoconstrictor response equivalent to that produced by NANC vagal stimulation. This response was significantly increased by injection of GABA. Baclofen had no significant effect on responses evoked by exogenous SP. 7. We conclude that GABA inhibits the release of transmitter from NANC nerves

  17. Purification and high-sensitivity membrane photoaffinity labeling of mammalian beta/sub 2/-adrenergic receptor

    SciTech Connect

    Drake, F.H. III

    1986-01-01

    The Beta/sub 2/-Adrenergic receptor (BAR) from guinea pig lung has been purified to near homogeneity. The purified BAR, detected by silver staining or by total radioiodination and autoradiography, migrates on SDS-PAGE as a broad band centered at 66 kilodaltons (kD). This band can be specifically labeled with the adrenergic photoaffinity ligand, /sup 125/I-azidobenzylpindolol. The purified BAR displays the same beta/sub 2/-subtype pharmacology and mobility on SDS-PAGE as the membrane-bound BAR. Microsequenator analysis of the purified BAR suggests that the amino terminus of the receptor is blocked. Several site-specific agents were used to fragment the purified BAR; some of the fragments may be useful for obtaining amino acid sequence of the BAR. Conditions also have developed for photoaffinity labeling the BAR in membranes of mammalian tissue culture cells (human astrocytoma, 1321N1) which contain very low levels of BAR. The BAR from these cells migrates as a broad band of about 66 kD on SDS-PAGE. Endoglycosidase F, which cleaves N-linked oligosaccharides, reduces the apparent molecular weight of the BAR from these cells to 45 kD. Recovery from agonist-induced down-regulation in post-confluent cultures of 1321N1 cells in the presence of tunicamycin (an inhibitor of N-linked glycosylation) results in the appearance of a 41 kD form of the BAR. Despite the apparent absence of N-linked oligosaccharides, this 41 kD form of the BAR retains adrenergic binding activity.

  18. Specific beta-adrenergic receptor binding of carazolol measured with PET

    SciTech Connect

    Berridge, M.S.; Nelson, A.D.; Zheng, L.

    1994-10-01

    Carazolol is a promising high-affinity beta-adrenergic receptor ligand for the noninvasive determination of beta receptor status using PET> Earlier investigations demonstrated specific receptor binding of carazolol in mice. These PET studies with S(-)-[2{double_prime}-{sup 11}C]carazolol in pigs were performed to explore the utility of the tracer for PET receptor studies. Tracer uptake in the heart and lung was measured by PET as a function of time. Receptors were blocked with propranolol and different doses of ICI 118,551 to estimate specific binding. Fluorine-18-1{double_prime}-Fluorocarazolol and the less active R-enantiomer of [{sup 11}C]-carazolol were also studied. Specific receptor binding was 75% of the total uptake in the heart, preventable and displaceable by propranolol. Dose-dependent competition showed that carazolol binds in vivo to {beta}{sub 1} and to {beta}{sub 2} subtypes. Uptake of the labeled R(=) enantiomer of carazolol was not receptor-specific. Carazolol labeled with {sup 11}C or {sup 18}F is a strong candidate for use in receptor estimation with PET. The in vivo observations were consistent with its known high affinity and slow receptor dissociation rate. Its high specific receptor uptake and low metabolism allow existing kinetic models to be applied for receptor measurements. The {sup 11}C label is convenient for repeated administrations, though {sup 13}F allowed the long observation periods necessary for measurement of the receptor dissociation rate. If needed, nonspecific uptake can be estimated without pharmacologic intervention by using the labeled R enantiomer. 32 refs., 11 figs.

  19. Effects of neonatal methylmercury exposure on adrenergic-receptor binding sites in peripheral tissues of the developing rat

    SciTech Connect

    Slotkin, T.A.; Kavlock, R.J.; Cowdery, T.; Orband, L.; Bartolome, M.

    1986-01-01

    Neonatal exposure to methylmercury produces changes in patterns of tissue growth and function, in part, due to alterations in adrenergic neuronal input. To explore the mechanisms by which these changes come about, newborn rats were exposed to methylmercury (1 or 2.5 mg/kg/day) throughout the preweaning stage and the ontogeny of adrenergic receptor binding sites evaluated in liver, kidney, heart and lung, using (/sup 3/H)prazosin (alpha 1-receptors), (/sup 3/H)rauwolscine (alpha 2-receptors) and (/sup 125/I)pindolol (beta-receptors). In the kidney, methylmercury caused decreases in beta- and alpha 1-receptor binding and increases in alpha 2-binding, and the alterations persisted into adulthood; previous work has shown that beta-receptor-mediated responses are generally enhanced in methylmercury-exposed pups, and the down-regulation of beta-receptor binding thus probably represents a compensatory action secondary to alterations in post-receptor coupling mechanisms. The effects of methylmercury on hepatic adrenergic receptors were different from those seen in the kidney, with substantial elevations in beta- and alpha-receptor binding apparent in the preweaning stage; this agrees also with the differences in effects of the mercurial on trophic reactivity and growth in the two tissues.

  20. Aryl biphenyl-3-ylmethylpiperazines as 5-HT7 receptor antagonists.

    PubMed

    Kim, Jeeyeon; Kim, Youngjae; Tae, Jinsung; Yeom, Miyoung; Moon, Bongjin; Huang, Xi-Ping; Roth, Bryan L; Lee, Kangho; Rhim, Hyewhon; Choo, Il Han; Chong, Youhoon; Keum, Gyochang; Nam, Ghilsoo; Choo, Hyunah

    2013-11-01

    The 5-HT7 receptor (5-HT7 R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5-HT7 R antagonist SB-269970 exhibited antidepressant-like activity, whereas systemic administration of the 5-HT7 R agonist AS-19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5-HT7 R antagonists or agonists, aryl biphenyl-3-ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5-HT7 R. Among the synthesized compounds, 1-([2'-methoxy-(1,1'-biphenyl)-3-yl]methyl)-4-(2-methoxyphenyl)piperazine (28) was the best binder to the 5-HT7 R (pKi =7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5-HT7 R over other serotonin receptor subtypes, such as 5-HT1 R, 5-HT2 R, 5-HT3 R, and 5-HT6 R. In a molecular modeling study, the 2-methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function. PMID:24039134

  1. Beta2-adrenergic receptor stimulation inhibits nitric oxide generation by Mycobacterium avium infected macrophages.

    PubMed

    Boomershine, C S; Lafuse, W P; Zwilling, B S

    1999-11-01

    Catecholamine regulation of nitric oxide (NO) production by IFNgamma-primed macrophages infected with Mycobacterium avium was investigated. Epinephrine treatment of IFNgamma-primed macrophages at the time of M. avium infection inhibited the anti-mycobacterial activity of the cells. The anti-mycobacterial activity of macrophages correlated with NO production. Using specific adrenergic receptor agonists, the abrogation of mycobacterial killing and decreased NO production by catecholamines was shown to be mediated via the beta2-adrenergic receptor. Elevation of intracellular cAMP levels mimicked the catecholamine-mediated inhibition of NO in both M. avium infected and LPS stimulated macrophages. Specific inhibitors of both adenylate cyclase and protein kinase A prevented the beta2-adrenoceptor-mediated inhibition of nitric oxide production. Beta2-adrenoreceptor stimulation at the time of M. avium infection of IFNgamma-primed macrophages also inhibited expression of iNOS mRNA. These observations show that catecholamine hormones can affect the outcome of macrophage-pathogen interactions and suggest that one result of sympathetic nervous system activation is the suppression of the capacity of macrophages to produce anti-microbial effector molecules. PMID:10580815

  2. Effects of superior cervical ganglionectomy on alpha 2 adrenergic receptors in dog cerebral arteries

    SciTech Connect

    Fujiwara, M.; Tsukahara, T.; Taniguchi, T.; Usui, H.

    1986-03-01

    Norepinephrine (NE)- and clonidine-induced contractions of dog cerebral arteries were attenuated by yohimbine but not affected by prazosin. There was no detectable /sup 3/H-prazosin binding site in the cerebral arteries. On the other hand, /sup 3/H-yohimbine binding studies revealed the presence of two binding sites with high and low affinities in the cerebral arteries. After superior cervical ganglionectomy, NE- and clonidine-induced contractions of the denervated cerebral arteries were not altered compared with the control arteries. The binding study revealed that there was low affinity /sup 3/H-yohimbine binding sites, whereas high affinity sites were not detectable. These results suggest that there are two different NE binding sites in alpha 2 adrenergic receptors, and that the high affinity sites are presynaptically located and low affinity sites are postsynaptic. It is also suggested that NE-induced contractions are mediated by postsynaptic low affinity sites of alpha 2 adrenergic receptors in the dog cerebral arteries.

  3. Glucocorticoids and beta-adrenergic-receptor agonists: their combined effect on fetal rabbit lung surfactant.

    PubMed

    Ekelund, L; Enhorning, G

    1985-08-15

    In a previous study on pregnant rabbits (Am J Obstet Gynecol 1983; 147:437) we found that a prolonged infusion of the beta 2-adrenergic-receptor agonist terbutaline would first cause a release of fetal pulmonary surfactant, so that more was available in the airways. However, the airway fluid then contained less surfactant, indicating a depletion of stores. Since terbutaline is often used in high doses as a tocolytic agent, surfactant depletion could be a serious side effect. With further studies on rabbits, we wanted to test the hypothesis that with an accelerated surfactant synthesis, achieved with glucocorticoids, the increased release, evoked with the terbutaline, would never cause a depletion of the surfactant stores. Our results supported this hypothesis. Betamethasone, administered to the pregnant doe on the twenty-sixth and twenty-seventh days of gestation, 0.1 mg/kg, increased compliance of the fetal lungs, and more phospholipid phosphorus could be lavaged from the airways. These effects were further increased when, following steroid administration, the doe was infused with terbutaline. Depletion of the surfactant stores was never seen when betamethasone was given prior to the beta-adrenergic-receptor agonist. PMID:3839627

  4. Astrocytic β2-adrenergic receptors mediate hippocampal long-term memory consolidation.

    PubMed

    Gao, Virginia; Suzuki, Akinobu; Magistretti, Pierre J; Lengacher, Sylvain; Pollonini, Gabriella; Steinman, Michael Q; Alberini, Cristina M

    2016-07-26

    Emotionally relevant experiences form strong and long-lasting memories by critically engaging the stress hormone/neurotransmitter noradrenaline, which mediates and modulates the consolidation of these memories. Noradrenaline acts through adrenergic receptors (ARs), of which β2-adrenergic receptors (βARs) are of particular importance. The differential anatomical and cellular distribution of βAR subtypes in the brain suggests that they play distinct roles in memory processing, although much about their specific contributions and mechanisms of action remains to be understood. Here we show that astrocytic rather than neuronal β2ARs in the hippocampus play a key role in the consolidation of a fear-based contextual memory. These hippocampal β2ARs, but not β1ARs, are coupled to the training-dependent release of lactate from astrocytes, which is necessary for long-term memory formation and for underlying molecular changes. This key metabolic role of astrocytic β2ARs may represent a novel target mechanism for stress-related psychopathologies and neurodegeneration. PMID:27402767

  5. N-terminal {beta}{sub 2}-adrenergic receptor polymorphisms do not correlate with bronchodilator response in asthma families

    SciTech Connect

    Holyroyd, K.J.; Dragwa, C.; Xu, J.

    1994-09-01

    Family and twin studies have suggested that susceptibility to asthma is inherited. One clinically relevant phenotype in asthma is the bronchodilator response to beta adrenergic therapy (reversibility) which may also be inherited and vary among asthmatics. Two polymorphisms of the {beta}{sub 2}-adrenergic receptor common to both asthmatic and normal individuals have been reported. One polymorphism, an amino acid polymorphism at position 16, correlated in one study with the need for long-term corticosteriod use in a population of asthmatics. It is conceivable that the increased use of corticosteroids needed to control symptoms in these patients may be explained by a decreased responsiveness to brochodilators mediated through this amino acid polymorphism in the {beta}{sub 2}-adrenergic receptor. However, the response to {beta}{sub 2} bronchodilators was not tested in these patients. In our Dutch asthma families, DNA sequencing of the {beta}{sub 2}-adrenergic receptor has been performed for N-terminal polymorphisms at amino acid positions 16 and 27 in over 100 individuals, and no correlation was found with the increase of FEV{sub 1} in response to bronchodilator. Linkage analysis between bronchodilator response and marker D5S412 near the {beta}{sub 2}-adrenergic receptor gene was performed in 286 sibpairs from these families. Using a bronchodilator response of >10% in FEV{sub 1} as a qualitative definition of affected individuals, there were 145 unaffected sibpairs, 121 sibpairs where one was affected, and 20 in which both were affected. Linear regression analysis of these sibpair data suggested possible linkage (p=0.007). This supports further examination of the {beta}{sub 2}-adrenergic receptor and its regulatory regions for polymorphisms that correlate with the bronchodilator response in asthma families.

  6. Rational design of high affinity tachykinin NK1 receptor antagonists.

    PubMed

    Boyle, S; Guard, S; Higginbottom, M; Horwell, D C; Howson, W; McKnight, A T; Martin, K; Pritchard, M C; O'Toole, J; Raphy, J

    1994-05-01

    The rational design of a non-peptide tachykinin NK1 receptor antagonist, [(2-benzofuran)-CH2OCO]-(R)-alpha-MeTrp-(S)-NHCH(CH3)P h (28, PD 154075) is described. Compound 28 has a Ki = 9 and 0.35 nM for the NK1 receptor binding site in guinea-pig cerebral cortex membranes and human IM9, cells respectively (using [125I] Bolton-Hunter-SP as the radioligand). It is a potent antagonist in vitro where it antagonises the contractions mediated by SPOMe in the guinea-pig ileum (KB = 0.3 nM). Compound 28 is active in vivo in the guinea-pig plasma extravasation model, where it is able to block the SPOMe-induced protein plasma extravasation (monitored by Evans Blue) in the bladder with an ID50 of 0.02 mg kg-1 iv. PMID:7922147

  7. Beneficial effects of desipramine on cognitive function of chronically stressed rats are mediated by alpha1-adrenergic receptors in medial prefrontal cortex

    PubMed Central

    Bondi, Corina O.; Jett, Julianne D.; Morilak, David A.

    2010-01-01

    Chronic stress is a risk factor for many psychopathological conditions, including depression and anxiety disorders. Cognitive impairments associated with prefrontal cortical dysfunction are a major component of such illnesses. Using an attentional set shifting test (AST), we have previously shown that elevating noradrenergic activity in rat medial prefrontal cortex (mPFC) can facilitate cognitive set-shifting, and that chronic unpredictable stress (CUS) caused set-shifting deficits. It is not known, however, if noradrenergic modulatory function is compromised by chronic stress, perhaps contributing to the stress-induced cognitive deficit. Thus, the first study investigated whether acutely elevating noradrenergic activity in mPFC still enhances cognitive function after chronic stress. As previously demonstrated, CUS impaired cognitive set-shifting on the AST. This deficit was abolished by acute systemic administration of the α2-adrenergic autoreceptor antagonist, atipamezole. Microdialysis revealed no differences in extracellular norepinephrine (NE) levels in mPFC of CUS-exposed and unstressed control rats at baseline or during behavioral testing, and comparable increases after atipamezole. In the second experiment, rats were treated chronically with the selective NE reuptake blocker, desipramine, during the CUS treatment through behavioral testing. Again, CUS impaired cognitive set-shifting in vehicle-treated rats, and chronic desipramine treatment prevented such deficits. Acute blockade of post-synaptic α1-adrenergic receptors in mPFC prior to testing blocked the beneficial effect of desipramine on cognitive set-shifting. These results suggest that desipramine restores cognitive set-shifting capability that has been compromised by chronic stress by activating α1-adrenergic receptors in the mPFC. Thus, noradrenergic modulatory capability in mPFC remains intact after CUS, and this represents one possible substrate by which antidepressants may exert their

  8. Discovery of aryloxy tetramethylcyclobutanes as novel androgen receptor antagonists.

    PubMed

    Guo, Chuangxing; Linton, Angelica; Kephart, Susan; Ornelas, Martha; Pairish, Mason; Gonzalez, Javier; Greasley, Samantha; Nagata, Asako; Burke, Benjamin J; Edwards, Martin; Hosea, Natilie; Kang, Ping; Hu, Wenyue; Engebretsen, Jon; Briere, David; Shi, Manli; Gukasyan, Hovik; Richardson, Paul; Dack, Kevin; Underwood, Toby; Johnson, Patrick; Morell, Andrew; Felstead, Robert; Kuruma, Hidetoshi; Matsimoto, Hiroaki; Zoubeidi, Amina; Gleave, Martin; Los, Gerrit; Fanjul, Andrea N

    2011-11-10

    An aryloxy tetramethylcyclobutane was identified as a novel template for androgen receptor (AR) antagonists via cell-based high-throughput screening. Follow-up to the initial "hit" established 5 as a viable lead. Further optimization to achieve full AR antagonism led to the discovery of 26 and 30, both of which demonstrated excellent in vivo tumor growth inhibition upon oral administration in a castration-resistant prostate cancer (CRPC) animal model. PMID:21936524

  9. The H2-receptor antagonist era in duodenal ulcer disease.

    PubMed Central

    Marks, I. N.

    1992-01-01

    This paper reviews the remarkable impact of H2-receptor antagonists on duodenal ulcer management. The development and the scientific rationale of these agents are presented, and efficacy and safety aspects in the short- and long-term treatment of duodenal ulcer disease discussed. Attention is focused on the possible role of "acid rebound" in ulcer relapse following the withdrawal of therapy and on the clinical relevance of prolonged suppression of acid secretion in patients on long-term therapy. PMID:1364125

  10. Estrogen Receptor Agonists and Antagonists in the Yeast Estrogen Bioassay.

    PubMed

    Wang, Si; Bovee, Toine F H

    2016-01-01

    Cell-based bioassays can be used to predict the eventual biological activity of a substance on a living organism. In vitro reporter gene bioassays are based on recombinant vertebrate cell lines or yeast strains and especially the latter are easy-to-handle, cheap, and fast. Moreover, yeast cells do not express estrogen, androgen, progesterone or glucocorticoid receptors, and are thus powerful tools in the development of specific reporter gene systems that are devoid of crosstalk from other hormone pathways. This chapter describes our experience with an in-house developed RIKILT yeast estrogen bioassay for testing estrogen receptor agonists and antagonists, focusing on the applicability of the latter. PMID:26585147

  11. Estrogen alters the diurnal rhythm of alpha 1-adrenergic receptor densities in selected brain regions

    SciTech Connect

    Weiland, N.G.; Wise, P.M.

    1987-11-01

    Norepinephrine regulates the proestrous and estradiol-induced LH surge by binding to alpha 1-adrenergic receptors. The density of alpha 1-receptors may be regulated by estradiol, photoperiod, and noradrenergic neuronal activity. We wished to determine whether alpha 1-receptors exhibit a diurnal rhythm in ovariectomized and/or estradiol-treated female rats, whether estradiol regulates alpha 1-receptors in those areas of brain involved with LH secretion and/or sexual behavior, and whether the concentrations of alpha-receptors vary inversely relative to previously reported norepinephrine turnover patterns. Young female rats, maintained on a 14:10 light-dark cycle were ovariectomized. One week later, half of them were outfitted sc with Silastic capsules containing estradiol. Groups of animals were decapitated 2 days later at 0300, 1000, 1300, 1500, 1800, and 2300 h. Brains were removed, frozen, and sectioned at 20 micron. Sections were incubated with (/sup 3/H)prazosin in Tris-HCl buffer, washed, dried, and exposed to LKB Ultrofilm. The densities of alpha 1-receptors were quantitated using a computerized image analysis system. In ovariectomized rats, the density of alpha 1-receptors exhibited a diurnal rhythm in the suprachiasmatic nucleus (SCN), medial preoptic nucleus (MPN), and pineal gland. In SCN and MPN, receptor concentrations were lowest during the middle of the day and rose to peak levels at 1800 h. In the pineal gland, the density of alpha 1-receptors was lowest at middark phase, rose to peak levels before lights on, and remained elevated during the day. Estradiol suppressed the density of alpha 1 binding sites in the SCN, MPN, median eminence, ventromedial nucleus, and the pineal gland but had no effect on the lateral septum. Estrogen treatment altered the rhythm of receptor densities in MPN, median eminence, and the pineal gland.

  12. Novel potent selective phenylglycine antagonists of metabotropic glutamate receptors.

    PubMed

    Bedingfield, J S; Jane, D E; Kemp, M C; Toms, N J; Roberts, P J

    1996-08-01

    The metabotropic glutamate (mGlu) receptor antagonist properties of novel phenylglycine analogues were investigated in adult rat cortical slices (mGlu receptors negatively coupled to adenylyl cyclase), neonatal rat cortical slices and in cultured rat cerebellar granule cells (mGlu receptors coupled to phosphoinositide hydrolysis). (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG), (RS)-alpha-methyl-4-sulphonophenylglycine (MSPG), (RS)-alpha-methyl-4-tetrazolylphenylglycine (MTPG), (RS)-alpha-methyl-3-carboxymethyl-4-hydroxyphenylglycine (M3CM4HPG) and (RS)-alpha-methyl-4-hydroxy-3-phosphonomethylphenylglycine (M4H3PMPG) were demonstrated to have potent and selective effects against 10 microM L-2-amino-4-phosphonobutyrate (L-AP4)- and 0.3 microM (2S,1'S,2'S)-2-(2-carboxycyclopropyl)glycine (L-CCG-1)-mediated inhibition of forskolin-stimulated cAMP accumulation in the adult rat cortex. In contrast, these compounds demonstrated either weak or no antagonism at mGlu receptors coupled to phosphoinositide hydrolysis in either neonatal rat cortex or in cultured cerebellar granule cells. These compounds thus appear to be useful discriminatory pharmacological tools for mGlu receptors and form the basis for the further development of novel antagonists. PMID:8864696

  13. A prototypical Sigma-1 receptor antagonist protects against brain ischemia

    PubMed Central

    Schetz, John A.; Perez, Evelyn; Liu, Ran; Chen, Shiuhwei; Lee, Ivan; Simpkins, James W.

    2016-01-01

    Previous studies indicate that the Sigma-1 ligand 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) protects the brain from ischemia. Less clear is whether protection is mediated by agonism or antagonism of the Sigma-1 receptor, and whether drugs already in use for other indications and that interact with the Sigma-1 receptor might also prevent oxidative damage due to conditions such as cerebral ischemic stroke. The antipsychotic drug haloperidol is an antagonist of Sigma-1 receptors and in this study it potently protects against oxidative stress-related cell death in vitro at low concentrations. The protective potency of haloperidol and a number of other butyrophenone compounds positively correlate with their affinity for a cloned Sigma-1 receptor, and the protection is mimicked by a Sigma-1 receptor-selective antagonist (BD1063), but not an agonist (PRE-084). In vivo, an acute low dose (0.05 mg/kg s.c.) of haloperidol reduces by half the ischemic lesion volume induced by a transient middle cerebral artery occlusion. These in vitro and in vivo pre-clinical results suggest that a low dose of acutely administered haloperidol might have a novel application as a protective agent against ischemic cerebral stroke and other types of brain injury with an ischemic component. PMID:17919467

  14. SB 242084, a selective and brain penetrant 5-HT2C receptor antagonist.

    PubMed

    Kennett, G A; Wood, M D; Bright, F; Trail, B; Riley, G; Holland, V; Avenell, K Y; Stean, T; Upton, N; Bromidge, S; Forbes, I T; Brown, A M; Middlemiss, D N; Blackburn, T P

    1997-01-01

    SB 242084 has a high affinity (pKi 9.0) for the cloned human 5-HT2C receptor and 100- and 158-fold selectivity over the closely related cloned human 5-HT2B and 5-HT2A subtypes respectively. SB 242084 had over 100-fold selectivity over a range of other 5-HT, dopamine and adrenergic receptors. In studies of 5-HT-stimulated phosphatidylinositol hydrolysis using SH-SY5Y cells stably expressing the cloned human 5-HT2C receptor, SB 242084 acted as an antagonist with a pKb of 9.3, which closely resembled its corresponding receptor binding affinity. SB 242084 potently inhibited m-chlorophenylpiperazine (mCPP, 7 mgkg i.p. 20 min pre-test)-induced hypolocomotion in rats, a model of in vivo central 5-HT2C receptor function, with an ID50 of 0.11 mg/kg i.p., and 2.0 mg/kg p.o. SB 242084 (0.1-1 mg/kg i.p.) exhibited an anxiolytic-like profile in the rat social interaction test, increasing time spent in social interaction, but having no effect on locomotion. SB 242084 (0.1-1 mg/kg i.p.) also markedly increased punished responding in a rat Geller-Seifter conflict test of anxiety, but had no consistent effect on unpunished responding. A large acute dose of SB 242084 (30 mg/kg p.o.) had no effect on seizure susceptibility in the rat maximal electroshock seizure threshold test. Also, while SB 242084 (2 and 6 mg/kg p.o. 1 hr pre-test) antagonized the hypophagic response to mCPP, neither acute nor subchronic administration of the drug, for 5 days at 2 or 6 mg/kg p.o. twice daily, affected food intake or weight gain. The results suggest that SB 242084 is the first reported selective potent and brain penetrant 5-HT2C receptor antagonist and has anxiolytic-like activity, but does not possess either proconvulsant or hyperphagic properties which are characteristic of mutant mice lacking the 5-HT2C receptor. PMID:9225286

  15. Targeting a family B GPCR/RAMP receptor complex: CGRP receptor antagonists and migraine

    PubMed Central

    Moore, Eric L; Salvatore, Christopher A

    2012-01-01

    The clinical effectiveness of antagonizing the calcitonin gene-related peptide (CGRP) receptor for relief of migraine pain has been clearly demonstrated, but the road to the development of these small molecule antagonists has been daunting. The key hurdle that needed to be overcome was the CGRP receptor itself. The vast majority of the current antagonists recognize similar epitopes on the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1). RAMP1 is a relatively small, single, transmembrane-spanning protein and along with the G-protein-coupled receptor CLR comprise a functional CGRP receptor. The tri-helical extracellular domain of RAMP1 plays a key role in the high affinity binding of CGRP receptor antagonists and drives their species-selective pharmacology. Over the years, a significant amount of mutagenesis data has been generated to identify specific amino acids or regions within CLR and RAMP1 that are critical to antagonist binding and has directed attention to the CLR/RAMP1 extracellular domain (ECD) complex. Recently, the crystal structure of the CGRP receptor ECD has been elucidated and not only reinforces the early mutagenesis data, but provides critical insight into the molecular mechanism of CGRP receptor antagonism. This review will highlight the drug design hurdles that must be overcome to meet the desired potency, selectivity and pharmacokinetic profile while retaining drug-like properties. Although the development of these antagonists has proved challenging, blocking the CGRP receptor may one day represent a new way to manage migraine and offer hope to migraine sufferers. LINKED ARTICLES This article is part of a themed section on Secretin Family (Class B) G Protein-Coupled Receptors. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.166.issue-1 PMID:21871019

  16. Inhibition of ionotropic neurotransmitter receptors by antagonists: strategy to estimate the association and the dissociation rate constant of antagonists with very strong affinity to the receptors.

    PubMed

    Aoshima, H; Inoue, Y; Hori, K

    1992-10-01

    Since binding of an agonist to an ionotropic neurotransmitter receptor causes not only channel opening, but also desensitization of the receptor, inhibition of the receptor by the antagonist sometimes becomes very complicated. The transient state kinetics of ligand association and dissociation, and desensitization of the receptor were considered on the basis of the minimal model proposed by Hess' group, and the following possibilities were proposed. 1) When an agonist is simultaneously applied to the receptor with an antagonist whose affinity to the receptor is extremely strong and different from that of the agonist, it is usually impossible to estimate the real inhibition constant exactly from the responses because desensitization of the receptor proceeds before the equilibrium of the ligand binding. Simultaneous addition of the antagonist with strong affinity to the receptor may apparently accelerate inactivation (desensitization) of the receptor. The association rate constant of the antagonist can be estimated by analyses of the rate of the inactivation in the presence and the absence of the antagonist. 2) A preincubated antagonist with a slow dissociation rate constant, i.e., a very effective inhibitor, may cause apparent noncompetitive inhibition of the receptor, since the receptor is desensitized by an agonist as soon as the antagonist dissociates from the receptor and the dissociation of the antagonist from the receptor becomes the rate-determining step. A nicotinic acetylcholine receptor (nAChR) was expressed in Xenopus oocytes by injecting mRNA prepared from Electrophorus electricus electroplax and used for the experiments on inhibition by an antagonist.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1337082

  17. Nonlinear relationship between alpha 1-adrenergic receptor occupancy and norepinephrine-stimulated calcium flux in cultured vascular smooth muscle cells

    SciTech Connect

    Colucci, W.S.; Brock, T.A.; Gimbrone, M.A. Jr.; Alexander, R.W.

    1985-05-01

    To determine the relationship between vascular alpha 1-adrenergic receptor occupancy and receptor-coupled calcium flux, the authors have studied (/sup 3/H)prazosin binding and l-norepinephrine-induced /sup 45/Ca efflux in cultured vascular smooth muscle cells isolated from the rabbit aorta. In a crude cellular homogenate, (/sup 3/H)prazosin bound to a single high affinity site, whereas l-norepinephrine (NE) binding was best described by a two-site model. NE-stimulated /sup 45/Ca efflux was concentration-dependent (EC/sup 50/ = 108 nM) and potently inhibited by prazosin (IC/sup 50/ = 0.15 nM). For the total receptor pool identified by (/sup 3/H)prazosin binding, the relationship between receptor occupancy by NE and NE-stimulated /sup 45/Ca efflux was markedly nonlinear, such that 50% of maximum NE-stimulated efflux occurred with occupancy of only approximately 7% of receptors. These two experimental approaches provide direct evidence for the presence in cultured rabbit aortic smooth muscle cells of a sizable pool of alpha 1-adrenergic receptors in excess of those needed for maximum NE-stimulated /sup 45/Ca efflux. This evidence of ''spare'' receptors, together with the finding of two affinity states of agonist binding, raises the possibility of functional heterogeneity of alpha 1-adrenergic receptors in this system.

  18. alpha. -Adrenergic vasoconstriction and receptor subtypes in large coronary arteries of calves

    SciTech Connect

    Young, M.A.; Vatner, D.E.; Knight, D.R.; Graham, R.M.; Homcy, C.J.; Vatner, S.F. New England Regional Primate Research Center, Southborough, MA )

    1988-12-01

    The authors investigated {alpha}-adrenoceptor subtype distribution in large coronary arteries from both functional and biochemical perspectives. The effects of intracoronary administration of the selective {alpha}{sub 1}-adrenoceptor agonist phenylephrine, of the selective {alpha}{sub 2}-adrenoceptor agonist B-HT 920 and of the mixed {alpha}{sub 1+2}-adrenoceptor agonist norepinephrine were examined on measurements of left circumflex coronary artery diameter in conscious calves. After {beta}-adrenergic blockade, equivalent reductions in large coronary artery diameter were observed with phenylephrine, B-HT, and norepinephrine. Phenylephrine-induced constrictions were abolished by prazosin, an {alpha}{sub 1}-selective antagonist, but unaffected by rauwolscine, an {alpha}{sub 2}-selective antagonist. Conversely, the B-HT-induced constriction was abolished by rauwolscine but unaffected by prazosin. Coronary constriction with norepinephrine was attenuated with either prazosin or rauwolscine and abolished by the two antagonists combined. Ligand-binding studies in which ({sup 3}H)prazosin and ({sup 3}H)rauwolscine and sarcolemmal membranes were used revealed an {alpha}{sub 1}-adrenoceptor density of 15 {plus minus} 3.1 fmol/mg protein with a dissociation constant (K{sub D}) of 0.7 {plus minus} 0.2 nM and an {alpha}{sub 2}-adrenoceptor density of 68 {plus minus} 5.1 fmol/mg protein, with a K{sub D} of 7.4 {plus minus} 1.2 nM. Thus large coronary arteries of the calf contain both {alpha}{sub 1}- and {alpha}{sub 2}-adrenoceptor subtypes, each of which elicits constriction of the large coronary artery in the conscious animal.

  19. Divergent Label-free Cell Phenotypic Pharmacology of Ligands at the Overexpressed β2-Adrenergic Receptors

    NASA Astrophysics Data System (ADS)

    Ferrie, Ann M.; Sun, Haiyan; Zaytseva, Natalya; Fang, Ye

    2014-01-01

    We present subclone sensitive cell phenotypic pharmacology of ligands at the β2-adrenergic receptor (β2-AR) stably expressed in HEK-293 cells. The parental cell line was transfected with green fluorescent protein (GFP)-tagged β2-AR. Four stable subclones were established and used to profile a library of sixty-nine AR ligands. Dynamic mass redistribution (DMR) profiling resulted in a pharmacological activity map suggesting that HEK293 endogenously expresses functional Gi-coupled α2-AR and Gs-coupled β2-AR, and the label-free cell phenotypic activity of AR ligands are subclone dependent. Pathway deconvolution revealed that the DMR of epinephrine is originated mostly from the remodeling of actin microfilaments and adhesion complexes, to less extent from the microtubule networks and receptor trafficking, and certain agonists displayed different efficacy towards the cAMP-Epac pathway. We demonstrate that receptor signaling and ligand pharmacology is sensitive to the receptor expression level, and the organization of the receptor and its signaling circuitry.

  20. Functionalized Congeners of P2Y1 Receptor Antagonists:

    SciTech Connect

    de Castro, Sonia; Maruoka, Hiroshi; Hong, Kunlun; Kilbey, II, S Michael; Costanzi, Stefano; Hechler, Béatrice; Gachet, Christian; Harden, T. Kendall; Jacobson, Kenneth A.

    2010-01-01

    The P2Y{sub 1} receptor is a prothrombotic G protein-coupled receptor (GPCR) activated by ADP. Preference for the North (N) ring conformation of the ribose moiety of adenine nucleotide 3',5'-bisphosphate antagonists of the P2Y{sub 1} receptor was established by using a ring-constrained methanocarba (a bicyclo[3.1.0]hexane) ring as a ribose substitute. A series of covalently linkable N{sup 6}-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphates containing extended 2-alkynyl chains was designed, and binding affinity at the human (h) P2Y{sub 1} receptor determined. The chain of these functionalized congeners contained hydrophilic moieties, a reactive substituent, or biotin, linked via an amide. Variation of the chain length and position of an intermediate amide group revealed high affinity of carboxylic congener 8 (K{sub i} 23 nM) and extended amine congener 15 (K{sub i} 132 nM), both having a 2-(1-pentynoyl) group. A biotin conjugate 18 containing an extended {epsilon}-aminocaproyl spacer chain exhibited higher affinity than a shorter biotinylated analogue. Alternatively, click coupling of terminal alkynes of homologous 2-dialkynyl nucleotide derivatives to alkyl azido groups produced triazole derivatives that bound to the P2Y{sub 1} receptor following deprotection of the bisphosphate groups. The preservation of receptor affinity of the functionalized congeners was consistent with new P2Y{sub 1} receptor modeling and ligand docking. Attempted P2Y{sub 1} antagonist conjugation to PAMAM dendrimer carriers by amide formation or palladium-catalyzed reaction between an alkyne on the dendrimer and a 2-iodopurine-derivatized nucleotide was unsuccessful. A dialkynyl intermediate containing the chain length favored in receptor binding was conjugated to an azide-derivatized dendrimer, and the conjugate inhibited ADP-promoted human platelet aggregation. This is the first example of attaching a strategically functionalized P2Y receptor antagonist to a PAMAM dendrimer to

  1. INFLUENCE OF CHLORDIMEFORM ON ALPHA-ADRENERGIC RECEPTOR-ASSOCIATED MECHANISMS OF HORMONAL REGULATIONS: PITUITARY AND ADRENOCORTICAL SECRETION

    EPA Science Inventory

    The acaricide chlordimeform (CDF) has been reported to have effects on the central nervous system that appear to involve an interaction with adrenergic receptor mediated mechanisms of neurotransmission. The present study examined the influence of CDF on pituitary-adrenocortical h...

  2. ADRENERGIC RECEPTOR GENOTYPE INFLUENCES THE EFFECTS OF STRENGTH TRAINING ON MID-THIGH INTER-MUSCULAR FAT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is little information regarding the effects of strength training (ST) on intermuscular fat (IMF), which can have adverse effects on health status in the elderly. Regional fat alterations resulting from exercise interventions may be influenced by adrenergic receptor (ADR) Beta2 Gln27Glu and AD...

  3. Pharmacological characterization of antagonists of the C5a receptor

    PubMed Central

    Paczkowski, Natalii J; Finch, Angela M; Whitmore, Jacqueline B; Short, Anna J; Wong, Allan K; Monk, Peter N; Cain, Stuart A; Fairlie, David P; Taylor, Stephen M

    1999-01-01

    Potent and highly selective small molecule antagonists have recently been developed by us for C5a receptors (C5aR) on human polymorphonuclear leukocytes (PMN). In this study we compared a new cyclic antagonist, F-[OPdChaWR], with an acyclic derivative, MeFKPdChaWr, for their capacities to bind to C5aR on human PMN and human umbilical artery membranes. We also compared their inhibition of myeloperoxidase (MPO) secretion from human PMNs and their inhibition of human umbilical artery contraction induced by human recombinant C5a.In both PMNs and umbilical artery, the cyclic and acyclic C5a antagonists displayed insurmountable antagonism against C5a. There were differences in selectivities for the C5aR with F-[OPdChaWR] (pKb 8.64±0.21) being 30 times more potent than MeFKPdChaWr (pKb 7.16±0.11, P<0.05) in PMNs, but of similar potency (pKb 8.19±0.38 vs pKb 8.28±0.29, respectively) in umbilical artery. This trend was also reflected in their relative binding affinities, both antagonists having similar affinities (−logIC50 values) for C5aR in umbilical artery membranes (F-[OPdChaWR], 7.00±0.46; MeFKPdChaWr, 7.23±0.17), whereas in PMN membranes the C5aR affinity of the cycle F-[OPdChaWR] (7.05±0.06) was four times higher than that of acyclic MeFKPdChaWr (6.43±0.24, P<0.05).In summary, the results reveal that these antagonists are insurmountable in nature against C5a for C5aR on at least two human cell types, and the differences in relative receptor binding affinities and antagonistic potencies against C5a are consistent with differences in receptors within these cell types. The nature of these differences is yet to be elucidated. PMID:10602324

  4. Characterization of a novel non-steroidal glucocorticoid receptor antagonist

    SciTech Connect

    Li, Qun-Yi; Zhang, Meng; Hallis, Tina M.; DeRosier, Therese A.; Yue, Jian-Min; Ye, Yang; Mais, Dale E.; Wang, Ming-Wei

    2010-01-15

    Selective antagonists of the glucocorticoid receptor (GR) are desirable for the treatment of hypercortisolemia associated with Cushing's syndrome, psychic depression, obesity, diabetes, neurodegenerative diseases, and glaucoma. NC3327, a non-steroidal small molecule with potent binding affinity to GR (K{sub i} = 13.2 nM), was identified in a high-throughput screening effort. As a full GR antagonist, NC3327 greatly inhibits the dexamethasone (Dex) induction of marker genes involved in hepatic gluconeogenesis, but has a minimal effect on matrix metalloproteinase 9 (MMP-9), a GR responsive pro-inflammatory gene. Interestingly, the compound recruits neither coactivators nor corepressors to the GR complex but competes with glucocorticoids for the interaction between GR and a coactivator peptide. Moreover, NC3327 does not trigger GR nuclear translocation, but significantly blocks Dex-induced GR transportation to the nucleus, and thus appears to be a 'competitive' GR antagonist. Therefore, the non-steroidal compound, NC3327, may represent a new class of GR antagonists as potential therapeutics for a variety of cortisol-related endocrine disorders.

  5. Modeling and simulation studies of human β3 adrenergic receptor and its interactions with agonists.

    PubMed

    Sahi, Shakti; Tewatia, Parul; Malik, Balwant K

    2012-12-01

    β3 adrenergic receptor (β3AR) is known to mediate various pharmacological and physiological effects such as thermogenesis in brown adipocytes, lipolysis in white adipocytes, glucose homeostasis and intestinal smooth muscle relaxation. Several efforts have been made in this field to understand their function and regulation in different human tissues and they have emerged as potential attractive targets in drug discovery for the treatment of diabetes, depression, obesity etc. Although the crystal structures of Bovine Rhodopsin and β2 adrenergic receptor have been resolved, to date there is no three dimensional structural information on β3AR. Our aim in this study was to model 3D structure of β3AR by various molecular modeling and simulation techniques. In this paper, we describe a refined predicted model of β3AR using different algorithms for structure prediction. The structural refinement and minimization of the generated 3D model of β3AR were done by Schrodinger suite 9.1. Docking studies of β3AR model with the known agonists enabled us to identify specific residues, viz, Asp 117, Ser 208, Ser 209, Ser 212, Arg 315, Asn 332, within the β3AR binding pocket, which might play an important role in ligand binding. Receptor ligand interaction studies clearly indicated that these five residues showed strong hydrogen bonding interactions with the ligands. The results have been correlated with the experimental data available. The predicted ligand binding interactions and the simulation studies validate the methods used to predict the 3D-structure. PMID:22242799

  6. Beta-adrenergic receptor sensitivity, autonomic balance and serotonergic activity in practitioners of Transcendental Meditation

    SciTech Connect

    Hill, D.A.

    1989-01-01

    The aim of this thesis was to investigate the acute autonomic effects of the Transcendental Meditation Program (TM) and resolve the conflict arising from discrepant neurochemical and psychophysiological data. Three experimental investigations were performed. The first examined beta{sub 2}-adrenergic receptors (AR's) on peripheral blood lymphocytes, via (I{sup 125})iodocyanopindolol binding, in 10 male mediating and 10 age matched non-meditating control subjects, to test the hypothesis that the long-term practice of TM and the TM Sidhi Program (TMSP) reduces end organ sensitivity to adrenergic agonists. The second investigated respiratory sinus arrhythmia (an indirect measure of cardiac Parasympathetic Nervous System tone), and skin resistance (a measure of Sympathetic Nervous System tone) during periods of spontaneous respiratory apneusis, a phenomenon occurring during TM that is known to mark the subjective experience of transcending. The third was within subject investigation of the acute effects of the TMSP on 5-hydroxytryptamine (5-HT) activity. Platelet 5-HT was assayed by high pressure liquid chromatography with electrochemical detection, plasma prolactin (PL) and lutenizing hormone (LH) by radioimmunoassay, tryptophan by spectrofluorimetry, and alpha-1-acid glycoprotein (AGP, a modulator of 5-HT uptake) by radial immunodiffusion assay.

  7. Reconstitution of beta-adrenergic receptor with components of adenylate cyclase.

    PubMed Central

    Hekman, M; Feder, D; Keenan, A K; Gal, A; Klein, H W; Pfeuffer, T; Levitzki, A; Helmreich, E J

    1984-01-01

    Beta 1-Adrenergic receptor proteins were extracted from turkey erythrocyte membranes with lauroyl sucrose and digitonin and purified by affinity chromatography on a column of alprenolol agarose Affi-gel 10 or 15. The 5000-fold purified receptor is able to couple functionally with the stimulatory GTP-binding protein (GS) from either turkey or duck erythrocytes. Functional coupling was achieved by three different approaches. (i) Purified beta-receptor polypeptides were coupled in phospholipid (asolectin) vesicles with GS from a crude cholate or lauroyl sucrose extract of turkey erythrocyte membranes. The detergent was removed and vesicles were formed with SM-2 beads. (ii) Purified beta-receptor was reconstituted with pure, homogeneous GS in asolectin vesicles. (iii) Purified beta-receptors were either coupled in asolectin vesicles with a mixture of pure, homogeneous Gpp(NH)p-activated GS and a lauroyl sucrose extract of turkey erythrocyte membranes, or with pure, homogeneous Gpp(NH)p-activated GS alone. The decay of activity was measured on addition of GTP and hormone. In (ii) and (iii), the detergent was removed and vesicles were formed by gel filtration on Sephadex G-50 columns. In each of the three different experimental conditions, the beta-receptor was activated with l-isoproterenol and activation was blocked with d,l-propranolol. Activated GS were measured separately by means of their capacity to activate a crude Lubrol PX-solubilized adenylate cyclase preparation from rabbit myocardial membrane. The kinetics of GS activation by purified beta-receptors occupied by l-isoproterenol was first order and activation was linearly dependent on receptor concentration.(ABSTRACT TRUNCATED AT 250 WORDS) Images Fig. 1. PMID:6098472

  8. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    PubMed Central

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  9. Crystal Structure of Antagonist Bound Human Lysophosphatidic Acid Receptor 1

    PubMed Central

    Chrencik, Jill E.; Roth, Christopher B.; Terakado, Masahiko; Kurata, Haruto; Omi, Rie; Kihara, Yasuyuki; Warshaviak, Dora; Nakade, Shinji; Asmar-Rovira, Guillermo; Mileni, Mauro; Mizuno, Hirotaka; Griffith, Mark T.; Rodgers, Caroline; Han, Gye Won; Velasquez, Jeffrey; Chun, Jerold; Stevens, Raymond C.

    2015-01-01

    Summary Lipid biology continues to emerge as an area of significant therapeutic interest, particularly as the result of an enhanced understanding of the wealth of signaling molecules with diverse physiological properties. This growth in knowledge is epitomized by lysophosphatidic acid (LPA), which functions through interactions with six cognate G protein-coupled receptors. Herein we present three crystal structures of LPA1 in complex with antagonist tool compounds selected and designed through structural and stability analysis. Structural analysis combined with molecular dynamics identified a basis for ligand access to the LPA1 binding pocket from the extracellular space contrasting with the proposed access for the sphingosine 1-phosphate receptor. Characteristics of the LPA1 binding pocket raise the possibility of promiscuous ligand recognition of phosphorylated endocannabinoids. Cell-based assays confirmed this hypothesis, linking the distinct receptor systems through metabolically related ligands with potential functional and therapeutic implications for treatment of disease. PMID:26091040

  10. Vasopressin receptor antagonists, heart failure, and polycystic kidney disease.

    PubMed

    Torres, Vicente E

    2015-01-01

    The synthesis of nonpeptide orally bioavailable vasopressin antagonists devoid of agonistic activity (vaptans) has made possible the selective blockade of vasopressin receptor subtypes for therapeutic purposes. Vaptans acting on the vasopressin V2 receptors (aquaretics) have attracted attention as a possible therapy for heart failure and polycystic kidney disease. Despite a solid rationale and encouraging preclinical testing, aquaretics have not improved clinical outcomes in randomized clinical trials for heart failure. Additional clinical trials with select population targets, more flexible dosing schedules, and possibly a different drug type or combination (balanced V1a/V2 receptor antagonism) may be warranted. Aquaretics are promising for the treatment of autosomal dominant polycystic kidney disease and have been approved in Japan for this indication. More studies are needed to better define their long-term safety and efficacy and optimize their utilization. PMID:25493947

  11. The identification of a selective dopamine D2 partial agonist, D3 antagonist displaying high levels of brain exposure.

    PubMed

    Holmes, Ian P; Blunt, Richard J; Lorthioir, Olivier E; Blowers, Stephen M; Gribble, Andy; Payne, Andrew H; Stansfield, Ian G; Wood, Martyn; Woollard, Patrick M; Reavill, Charlie; Howes, Claire M; Micheli, Fabrizio; Di Fabio, Romano; Donati, Daniele; Terreni, Silvia; Hamprecht, Dieter; Arista, Luca; Worby, Angela; Watson, Steve P

    2010-03-15

    The identification of a highly selective D(2) partial agonist, D(3) antagonist tool molecule which demonstrates high levels of brain exposure and selectivity against an extensive range of dopamine, serotonin, adrenergic, histamine, and muscarinic receptors is described. PMID:20153647

  12. Pinpointing beta adrenergic receptor in ageing pathophysiology: victim or executioner? Evidence from crime scenes

    PubMed Central

    2013-01-01

    G protein-coupled receptors (GPCRs) play a key role in cellular communication, allowing human cells to sense external cues or to talk each other through hormones or neurotransmitters. Research in this field has been recently awarded with the Nobel Prize in chemistry to Robert J. Lefkowitz and Brian K. Kobilka, for their pioneering work on beta adrenergic receptors (βARs), a prototype GPCR. Such receptors, and β2AR in particular, which is extensively distributed throughout the body, are involved in a number of pathophysiological processes. Moreover, a large amount of studies has demonstrated their participation in ageing process. Reciprocally, age-related changes in regulation of receptor responses have been observed in numerous tissues and include modifications of βAR responses. Impaired sympathetic nervous system function has been indeed evoked as at least a partial explanation for several modifications that occur with ageing. This article represents an updated presentation of the current knowledge in the field, summarizing in a systematic way the major findings of research on ageing in several organs and tissues (crime scenes) expressing βARs: heart, vessels, skeletal muscle, respiratory system, brain, immune system, pancreatic islets, liver, kidney and bone. PMID:23497413

  13. Food restriction prevents an age-associated increase in rat liver beta-adrenergic receptors

    SciTech Connect

    Dax, E.M.; Ingram, D.K.; Partilla, J.S.; Gregerman, R.I.

    1989-05-01

    In male Wistar rats fed ad libitum (24% protein, 4.5 Kcal/gm), the (/sup 125/I)iodopindolol binding capacity of the beta-adrenergic receptors in liver of 24-month-old animals is 3-4 times greater than that of 6-month-old counterparts. In rats fed the same diet, on alternate days from weaning, the receptor capacity did not increase significantly between 6 and 24 months (10.20 +/- 0.55 vs 9.20 +/- 0.72 fmol/mg) or between 24 and 30 months. This was not due to acute dietary deprivation, as rats food-restricted for only 2 weeks, at 23.5 months of age, also showed elevated receptor capacities compared to 6-month-old ad libitum fed animals. Moreover, intermittent feeding produced no significant effects among 6-month-old animals, whether restricted since weaning or for two weeks prior to sacrifice. Many biochemical parameters that decrease with aging in rats fed ad libitum are prevented by dietary restriction. Our results demonstrate that a reproducible biochemical process that increases with aging is also prevented with dietary restriction. The age-related, liver beta-receptor increase may be a potentially reliable marker for studying biochemical perturbations that modify life span.

  14. Discovery of novel acetanilide derivatives as potent and selective beta3-adrenergic receptor agonists.

    PubMed

    Maruyama, Tatsuya; Onda, Kenichi; Hayakawa, Masahiko; Matsui, Tetsuo; Takasu, Toshiyuki; Ohta, Mitsuaki

    2009-06-01

    In the search for potent and selective human beta3-adrenergic receptor (AR) agonists as potential drugs for the treatment of obesity and noninsulin-dependent (type II) diabetes, a novel series of acetanilide-based analogues were prepared and their biological activities were evaluated at the human beta3-, beta2-, and beta1-ARs. Among these compounds, 2-pyridylacetanilide (2f), pyrimidin-2-ylacetanilide (2u), and pyrazin-2-ylacetanilide (2v) derivatives exhibited potent agonistic activity at the beta3-AR with functional selectivity over the beta1- and beta2-ARs. In particular, compound 2u was found to be the most potent and selective beta3-AR agonist with an EC(50) value of 0.11 microM and no agonistic activity for either the beta1- or beta2-AR. In addition, 2f, 2u, and 2v showed significant hypoglycemic activity in a rodent diabetic model. PMID:19232786

  15. Adrenaline Rush: The Role of Adrenergic Receptors in Stimulant-Induced Behaviors

    PubMed Central

    Schmidt, Karl T.

    2014-01-01

    Psychostimulants, such as cocaine and amphetamines, act primarily through the monoamine neurotransmitters dopamine (DA), norepinephrine, and serotonin. Although stimulant addiction research has largely focused on DA, medication development efforts targeting the dopaminergic system have thus far been unsuccessful, leading to alternative strategies aimed at abating stimulant abuse. Noradrenergic compounds have shown promise in altering the behavioral effects of stimulants in rodents, nonhuman primates, and humans. In this review, we discuss the contribution of each adrenergic receptor (AR) subtype (α1, α2, and β) to five stimulant-induced behaviors relevant to addiction: locomotor activity, conditioned place preference, anxiety, discrimination, and self-administration. AR manipulation has diverse effects on these behaviors; each subtype profoundly influences outcomes in some paradigms but is inconsequential in others. The functional neuroanatomy and intracellular signaling mechanisms underlying the impact of AR activation/blockade on these behaviors remain largely unknown, presenting a new frontier for research on psychostimulant–AR interactions. PMID:24499709

  16. Evidence for the presence of beta 3-adrenergic receptor mRNA in the human brain.

    PubMed

    Rodriguez, M; Carillon, C; Coquerel, A; Le Fur, G; Ferrara, P; Caput, D; Shire, D

    1995-04-01

    The beta 3-adrenergic receptor (AR) is widely distributed in peripheral tissues, but up to now it has not been detected in the central nervous system. By using the polymerase chain reaction (PCR) technique, we found the beta 3-AR mRNA to be present in all the regions of the human brain we investigated. The quantities found were very low compared to those of the beta 1-AR and beta 2-AR mRNAs, being hardly detectable in adult brain. In contrast, the brain of very young infants contained about 100 times more beta 3-AR mRNA than the adult brain, whereas the amounts of beta 1-AR and beta 2-AR transcripts were essentially the same. In addition, using PCR we have cloned a central beta 3-AR coding region from a human frontal cortex cDNA library and have found it to be identical to the corresponding peripheral sequence. PMID:7609625

  17. Nicotinic Receptor Antagonists as Treatments for Nicotine Abuse

    PubMed Central

    Crooks, Peter A.; Bardo, Michael T.; Dwoskin, Linda P.

    2014-01-01

    Despite the proven efficacy of current pharmacotherapies for tobacco dependence, relapse rates continue to be high, indicating that novel medications are needed. Currently, several smoking cessation agents are available, including varenicline (Chantix®), bupropion (Zyban®), and cytisine (Tabex®). Varenicline and cytisine are partial agonists at the α4β2* nicotinic acetylcholine receptor (nAChR). Bupropion is an antidepressant but is also an antagonist at α3β2* ganglionic nAChRs. The rewarding effects of nicotine are mediated, in part, by nicotine-evoked dopamine (DA) release leading to sensitization, which is associated with repeated nicotine administration and nicotine addiction. Receptor antagonists that selectivity target central nAChR subtypes mediating nicotine-evoked DA release should have efficacy as tobacco use cessation agents with the therapeutic advantage of a limited side-effect profile. While α-conotoxin MII (α-CtxMII)-insensitive nAChRs (e.g., α4β2*) contribute to nicotine-evoked DA release, these nAChRs are widely distributed in the brain, and inhibition of these receptors may lead to nonselective and untoward effects. In contrast, α-CtxMII-sensitive nAChRs mediating nicotine-evoked DA release offer an advantage as targets for smoking cessation, due to their more restricted localization primarily to dopaminergic neurons. Small drug-like molecules that are selective antagonists at α-CtxMII-sensitive nAChR subtypes that contain α6 and β2 subunits have now been identified. Early research identified a variety of quaternary ammonium analogs that were potent and selective antagonists at nAChRs mediating nicotine-evoked DA release. More recent data have shown that novel, non-quaternary bis-1,2,5,6-tetrahydropyridine analogs potently inhibit (IC50<1 nM) nicotine-evoked DA release in vitro by acting as antagonists at α-CtxMII-sensitive nAChR subtypes; these compounds also decrease NIC self-administration in rats. PMID:24484986

  18. Activation of spinal α2 adrenergic receptors induces hyperglycemia in mouse though activating sympathetic outflow.

    PubMed

    Sim, Yun-Beom; Park, Soo-Hyun; Kim, Sung-Su; Lim, Su-Min; Jung, Jun-Sub; Suh, Hong-Won

    2014-10-15

    The roles of α2-adrenergic receptors located in the spinal cord in the regulation of blood glucose levels were studied in imprinting control region (ICR) mice. Mice were treated intrathecally (i.t.) with clonidine or yohimbine, and the blood glucose levels were measured at 0, 30, 60 and 120min after i.t. administration. The i.t. injection with clonidine caused a pronounced elevation of the blood glucose levels in a dose-dependent manner. Clonidine-induced hyperglycemic effect was dose-dependently attenuated by i.t. pretreatment with yohimbine. Furthermore, plasma insulin level was attenuated by clonidine, and yohimbine pretreatment reversed partially, but significantly, clonidine-induced down-regulation of the plasma insulin level. I.t. pretreatment with pertussis toxin (PTX) almost abolished the hyperglycemic effect induced by clonidine. PTX pretreatment reversed the induced down-regulation of the insulin level. In addition, i.t. pretreatment with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) or intraperitoneal (i.p.) pretreatment with mifepristone, hexamethonium and 6-hydroxydopamine (6-OHDA) attenuated the hyperglycemic effect induced by clonidine. I.t. injected clonidine significantly increased plasma corticosterone level. The elevated blood glucose level induced by clonidine was significantly decreased in adrenalectomized (ADX) mice. Our results suggest that the α2-adrenergic receptors located in the spinal cord play important roles for the elevation of the blood glucose level. The hyperglycemic effect induced by clonidine appears to be mediated by a reduction of the plasma insulin level. In addition, glucocortioid system appears to be involved in clonidine-induced hyperglycemic effect. Furthermore, the clonidine-induced hyperglycemia appears to be mediated via activating the spinal nerves or peripheral sympathetic nervous system. PMID:25179570

  19. Dissociation between neural and vascular responses to sympathetic stimulation : contribution of local adrenergic receptor function

    NASA Technical Reports Server (NTRS)

    Jacob, G.; Costa, F.; Shannon, J.; Robertson, D.; Biaggioni, I.

    2000-01-01

    Sympathetic activation produced by various stimuli, eg, mental stress or handgrip, evokes regional vascular responses that are often nonhomogeneous. This phenomenon is believed to be the consequence of the recruitment of differential central neural pathways or of a sympathetically mediated vasodilation. The purpose of this study was to determine whether a similar heterogeneous response occurs with cold pressor stimulation and to test the hypothesis that local differences in adrenergic receptor function could be in part responsible for this diversity. In 8 healthy subjects, local norepinephrine spillover and blood flow were measured in arms and legs at baseline and during sympathetic stimulation induced by baroreflex mechanisms (nitroprusside infusion) or cold pressor stimulation. At baseline, legs had higher vascular resistance (27+/-5 versus 17+/-2 U, P=0.05) despite lower norepinephrine spillover (0.28+/-0.04 versus 0.4+/-0.05 mg. min(-1). dL(-1), P=0.03). Norepinephrine spillover increased similarly in both arms and legs during nitroprusside infusion and cold pressor stimulation. On the other hand, during cold stimulation, vascular resistance increased in arms but not in legs (20+/-9% versus -7+/-4%, P=0.03). Increasing doses of isoproterenol and phenylephrine were infused intra-arterially in arms and legs to estimate beta-mediated vasodilation and alpha-induced vasoconstriction, respectively. beta-Mediated vasodilation was significantly lower in legs compared with arms. Thus, we report a dissociation between norepinephrine spillover and vascular responses to cold stress in lower limbs characterized by a paradoxical decrease in local resistance despite increases in sympathetic activity. The differences observed in adrenergic receptor responses cannot explain this phenomenon.

  20. The effects of estrogen on the α2-adrenergic receptor subtypes in rat uterine function in late pregnancy in vitro

    PubMed Central

    Hajagos-Tóth, Judit; Bóta, Judit; Ducza, Eszter; Csányi, Adrienn; Tiszai, Zita; Borsodi, Anna; Samavati, Reza; Benyhe, Sándor; Gáspár, Róbert

    2016-01-01

    Aim To assess the effect of 17β-estradiol pretreatment on the function and expression of α2- adrenergic receptors (ARs) subtypes in late pregnancy in rats. Methods Sprague-Dawley SPD rats (n = 37) were treated with 17β-estradiol for 4 days starting from the 18th day of pregnancy. The myometrial expression of the α2-AR subtypes was determined by real time polymerase chain reaction and Western blot analysis. In vitro contractions were stimulated with (-)-noradrenaline, and its effect was modified with the selective antagonists BRL 44408 (α2A), ARC 239 (α2B/C), and spiroxatrine (α2A). The cyclic adenosine monophosphate (cAMP) accumulation was also measured. The activated G-protein level was investigated by guanosine 5′-O-[gamma-thio]triphosphate (GTPγS) binding assay. Results 17β-estradiol pretreatment decreased the contractile effect of (-)-noradrenaline via the α2-ARs, and abolished the contractile effect via the α2B-ARs. All the α2-AR subtypes’ mRNA was significantly decreased. 17β-estradiol pretreatment significantly increased the myometrial cAMP level in the presence of BRL 44408 (P = 0.001), ARC 239 (P = 0.007), and spiroxatrine (P = 0.045), but did not modify it in the presence of spiroxatrine + BRL 44408 combination (P = 0.073). It also inhibited the G-protein-activating effect of (-)-noradrenaline by 25% in the presence of BRL 44408 + spiroxatrine combination. Conclusions The expression of the α2-AR subtypes is sensitive to 17β-estradiol, which decreases the contractile response of (-)-noradrenaline via the α2B-AR subtype, and might cause changes in G-protein signaling pathway. Estrogen dysregulation may be responsible for preterm labor or uterine inertia via the α2-ARs. PMID:27106352

  1. Effect of β2‐adrenergic receptor polymorphisms on epinephrine and exercise‐stimulated lipolysis in humans

    PubMed Central

    Du, Shichun; Joyner, Michael J.; Curry, Timothy B.; Eisenach, John H.; Johnson, Christopher P.; Schrage, William G.; Jensen, Michael D.

    2014-01-01

    Abstract The β2‐adrenergic system is an important regulator of human adipose tissue lipolysis. Polymorphisms that result in amino acid substitutions in the β2‐adrenergic receptor have been reported to alter lipolysis. We hypothesized that variations in the amino acid at position 16 of the β2‐adrenergic receptor would result in different lipolytic responses to intravenous epinephrine and exercise. 17 volunteers homozygous for glycine at position 16 (Gly/Gly, nine female) and 16 volunteers homozygous for arginine at position 16 (Arg/Arg, eight female) of the β2‐adrenergic receptor participated in this study. On one study day participants received infusions of epinephrine at submaximal (5 ng kg−1 min−1) and maximal (40 ng kg−1 min−1) lipolytic doses. The other study day volunteers bicycled for 90 min at 50–60% of maximum oxygen consumption (VO2max). [9,10‐3H] Palmitate was infused both days to measure free fatty acid – palmitate kinetics. Oxygen consumption was measured using indirect calorimetry. Palmitate release rates in response to epinephrine and exercise were not different in the Gly/Gly and Arg/Arg participants. The only statistically significant difference we observed was a lesser ΔVO2 in Arg/Arg volunteers in response to the submaximal epinephrine infusion. The polymorphisms resulting in Arg/Arg and Gly/Gly at position 16 of the β2‐adrenergic receptor do not result in clinically meaningful differences in lipolysis responses to epinephrine or submaximal exercise. PMID:24844639

  2. GABAA receptor modulating steroid antagonists (GAMSA) are functional in vivo.

    PubMed

    Johansson, Maja; Strömberg, Jessica; Ragagnin, Gianna; Doverskog, Magnus; Bäckström, Torbjörn

    2016-06-01

    GABAA receptor modulating steroid antagonists (GAMSA) selectively inhibit neurosteroid-mediated enhancement of GABA-evoked currents at the GABAA receptor. 3α-hydroxy-neurosteroids, notably allopregnanolone and tetrahydrodeoxycorticosterone (THDOC), potentiate GABAA receptor-mediated currents. On the contrary, various 3β-hydroxy-steroids antagonize this positive neurosteroid-mediated modulation. Importantly, GAMSAs are specific antagonists of the positive neurosteroid-modulation of the receptor and do not inhibit GABA-evoked currents. Allopregnanolone and THDOC have both negative and positive actions. Allopregnanolone can impair encoding/consolidation and retrieval of memories. Chronic administration of a physiological allopregnanolone concentration reduces cognition in mice models of Alzheimer's disease. In humans an allopregnanolone challenge impairs episodic memory and in hepatic encephalopathy cognitive deficits are accompanied by increased brain ammonia and allopregnanolone. Hippocampal slices react in vitro to ammonia by allopregnanolone synthesis in CA1 neurons, which blocks long-term potentiation (LTP). Thus, allopregnanolone may impair learning and memory by interfering with hippocampal LTP. Contrary, pharmacological treatment with allopregnanolone can promote neurogenesis and positively influence learning and memory of trace eye-blink conditioning in mice. In rat the GAMSA UC1011 inhibits an allopregnanolone-induced learning impairment and the GAMSA GR3027 restores learning and motor coordination in rats with hepatic encephalopathy. In addition, the GAMSA isoallopregnanolone antagonizes allopregnanolone-induced anesthesia in rats, and in humans it antagonizes allopregnanolone-induced sedation and reductions in saccadic eye velocity. 17PA is also an effective GAMSA in vivo, as it antagonizes allopregnanolone-induced anesthesia and spinal analgesia in rats. In vitro the allopregnanolone/THDOC-increased GABA-mediated GABAA receptor activity is antagonized

  3. β2 Adrenergic Receptor Fluorescent Protein Fusions Traffic to the Plasma Membrane and Retain Functionality

    PubMed Central

    Bubnell, Jaclyn; Pfister, Patrick; Sapar, Maria L.; Rogers, Matthew E.; Feinstein, Paul

    2013-01-01

    Green fluorescent protein (GFP) has proven useful for the study of protein interactions and dynamics for the last twenty years. A variety of new fluorescent proteins have been developed that expand the use of available excitation spectra. We have undertaken an analysis of seven of the most useful fluorescent proteins (XFPs), Cerulean (and mCerulean3), Teal, GFP, Venus, mCherry and TagRFP657, as fusions to the archetypal G-protein coupled receptor, the β2 adrenergic receptor (β2AR). We have characterized these β2AR::XFP fusions in respect to membrane trafficking and G-protein activation. We noticed that in the mouse neural cell line, OP 6, that membrane bound β2AR::XFP fusions robustly localized in the filopodia identical to gap::XFP fusions. All β2AR::XFP fusions show responses indistinguishable from each other and the non-fused form after isoprenaline exposure. Our results provide a platform by which G-protein coupled receptors can be dissected for their functionality. PMID:24086401

  4. Structural insights into the dynamic process of β2-adrenergic receptor signaling

    PubMed Central

    Manglik, Aashish; Kim, Tae Hun; Masureel, Matthieu; Altenbach, Christian; Yang, Zhongyu; Hilger, Daniel; Lerch, Michael T.; Kobilka, Tong Sun; Thian, Foon Sun; Hubbell, Wayne L.; Prosser, R. Scott; Kobilka, Brian K.

    2015-01-01

    SUMMARY G protein-coupled receptors (GPCRs) transduce signals from the extracellular environment to intracellular proteins. To gain structural insight into the regulation of receptor cytoplasmic conformations by extracellular ligands during signaling, we examine the structural dynamics of the cytoplasmic domain of the β2-adrenergic receptor (β2AR) using 19F-fluorine NMR and double electron-electron resonance spectroscopy. These studies show that unliganded and inverse-agonist-bound β2AR exists predominantly in two inactive conformations that exchange within hundreds of microseconds. Although agonists shift the equilibrium towards a conformation capable of engaging cytoplasmic G proteins, they do so incompletely, resulting in increased conformational heterogeneity and the coexistence of inactive, intermediate and active states. Complete transition to the active conformation requires subsequent interaction with a G-protein or an intracellular G protein mimetic. These studies demonstrate a loose allosteric coupling of the agonist-binding site and G protein-coupling interface that may generally be responsible for the complex signaling behavior observed for many GPCRs. PMID:25981665

  5. Crystal structure of the β2 adrenergic receptor-Gs protein complex

    SciTech Connect

    Rasmussen, Søren G.F.; DeVree, Brian T; Zou, Yaozhong; Kruse, Andrew C; Chung, Ka Young; Kobilka, Tong Sun; Thian, Foon Sun; Chae, Pil Seok; Pardon, Els; Calinski, Diane; Mathiesen, Jesper M; Shah, Syed T.A.; Lyons, Joseph A; Caffrey, Martin; Gellman, Samuel H; Steyaert, Jan; Skiniotis, Georgios; Weis, William I; Sunahara, Roger K; Kobilka, Brian K

    2011-12-07

    G protein-coupled receptors (GPCRs) are responsible for the majority of cellular responses to hormones and neurotransmitters as well as the senses of sight, olfaction and taste. The paradigm of GPCR signalling is the activation of a heterotrimeric GTP binding protein (G protein) by an agonist-occupied receptor. The β2 adrenergic receptor2AR) activation of Gs, the stimulatory G protein for adenylyl cyclase, has long been a model system for GPCR signalling. Here we present the crystal structure of the active state ternary complex composed of agonist-occupied monomeric β2AR and nucleotide-free Gs heterotrimer. The principal interactions between the β2AR and Gs involve the amino- and carboxy-terminal α-helices of Gs, with conformational changes propagating to the nucleotide-binding pocket. The largest conformational changes in the β2AR include a 14Å outward movement at the cytoplasmic end of transmembrane segment 6 (TM6) and an α-helical extension of the cytoplasmic end of TM5. The most surprising observation is a major displacement of the α-helical domain of Gαs relative to the Ras-like GTPase domain. This crystal structure represents the first high-resolution view of transmembrane signalling by a GPCR.

  6. Structural insights and functional implications of inter-individual variability in β2-adrenergic receptor

    PubMed Central

    Tandale, Aditi; Joshi, Manali; Sengupta, Durba

    2016-01-01

    The human β2-adrenergic receptor (β2AR) belongs to the G protein-coupled receptor (GPCR) family and due to its central role in bronchodilation, is an important drug target. The inter-individual variability in β2AR has been implicated in disease susceptibility and differential drug response. In this work, we identified nine potentially deleterious non-synonymous single nucleotide polymorphisms (nsSNPs) using a consensus approach. The deleterious nsSNPs were found to cluster near the ligand binding site and towards the G-protein binding site. To assess their molecular level effects, we built structural models of these receptors and performed atomistic molecular dynamics simulations. Most notably, in the Phe290Ser variant we observed the rotameric flip of Trp2866.48, a putative activation switch that has not been reported in β2AR thus far. In contrast, the variant Met82Lys was found to be the most detrimental to epinephrine binding. Additionally, a few of the nsSNPs were seen to cause perturbations to the lipid bilayer, while a few lead to differences at the G-protein coupling site. We are thus able to classify the variants as ranging from activating to damaging, prioritising them for experimental studies. PMID:27075228

  7. Anti-β1-adrenergic receptor autoantibodies in patients with chronic Chagas heart disease

    PubMed Central

    Labovsky, V; Smulski, C R; Gómez, K; Levy, G; Levin, M J

    2007-01-01

    Chronic Chagas heart disease (cChHD), a chronic manifestation of the Trypanosoma cruzi infection, is characterized by high antibody levels against the C-terminal region of the ribosomal P proteins (i.e. peptide R13, EEEDDDMGFGLFD) which bears similarity with the second extracellular loop of β1-adrenergic receptor (β1-AR, peptide H26R HWWRAESDEARRCYNDPKCCDFVTNR). Because it has not been demonstrated clearly that IgGs from cChHD patients bind to native human β1-AR, the aim of this study was to investigate further the physical interaction between cChHD IgGs and the human β1-AR. Immunofluorescence assays demonstrated the binding of these antibodies to the receptor expressed on stably transfected cells, together with a β1-AR agonist-like effect. In addition, immunoadsorption of the serum samples from cChHD patients with a commercially available matrix, containing peptides representing the first and the second extracellular loop of the β1-AR, completely abolished reactivity against the H26R peptide and the physiological response to the receptor. The follow-up of this specificity after in vitro immunoadsorption procedures suggests that this treatment might be used to diminish significantly the serum levels of anti-β1-AR antibodies in patients with Chagas heart disease. PMID:17419712

  8. Crystal Structure of the β2Adrenergic Receptor-Gs protein complex

    PubMed Central

    Rasmussen, Søren G.F.; DeVree, Brian T.; Zou, Yaozhong; Kruse, Andrew C.; Chung, Ka Young; Kobilka, Tong Sun; Thian, Foon Sun; Chae, Pil Seok; Pardon, Els; Calinski, Diane; Mathiesen, Jesper M.; Shah, Syed T. A.; Lyons, Joseph A.; Caffrey, Martin; Gellman, Samuel H.; Steyaert, Jan; Skiniotis, Georgios; Weis, William I.; Sunahara, Roger K.; Kobilka, Brian K.

    2011-01-01

    G protein-coupled receptors (GPCRs) are responsible for the majority of cellular responses to hormones and neurotransmitters as well as the senses of sight, olfaction and taste. The paradigm of GPCR signaling is the activation of a heterotrimeric GTP binding protein (G protein) by an agonist-occupied receptor. The β2 adrenergic receptor (β2AR) activation of Gs, the stimulatory G protein for adenylyl cyclase, has long been a model system for GPCR signaling. Here we present the crystal structure of the active state ternary complex composed of agonist-occupied monomeric β2AR and nucleotide-free Gs heterotrimer. The principal interactions between the β2AR and Gs involve the amino and carboxyl terminal α-helices of Gs, with conformational changes propagating to the nucleotide-binding pocket. The largest conformational changes in the β2AR include a 14 Å outward movement at the cytoplasmic end of transmembrane segment 6 (TM6) and an alpha helical extension of the cytoplasmic end of TM5. The most surprising observation is a major displacement of the alpha helical domain of Gαs relative to the ras-like GTPase domain. This crystal structure represents the first high-resolution view of transmembrane signaling by a GPCR. PMID:21772288

  9. Cardiac Alpha1-Adrenergic Receptors: Novel Aspects of Expression, Signaling Mechanisms, Physiologic Function, and Clinical Importance

    PubMed Central

    O’Connell, Timothy D.; Jensen, Brian C.; Baker, Anthony J.

    2014-01-01

    Adrenergic receptors (AR) are G-protein-coupled receptors (GPCRs) that have a crucial role in cardiac physiology in health and disease. Alpha1-ARs signal through Gαq, and signaling through Gq, for example, by endothelin and angiotensin receptors, is thought to be detrimental to the heart. In contrast, cardiac alpha1-ARs mediate important protective and adaptive functions in the heart, although alpha1-ARs are only a minor fraction of total cardiac ARs. Cardiac alpha1-ARs activate pleiotropic downstream signaling to prevent pathologic remodeling in heart failure. Mechanisms defined in animal and cell models include activation of adaptive hypertrophy, prevention of cardiac myocyte death, augmentation of contractility, and induction of ischemic preconditioning. Surprisingly, at the molecular level, alpha1-ARs localize to and signal at the nucleus in cardiac myocytes, and, unlike most GPCRs, activate “inside-out” signaling to cause cardioprotection. Contrary to past opinion, human cardiac alpha1-AR expression is similar to that in the mouse, where alpha1-AR effects are seen most convincingly in knockout models. Human clinical studies show that alpha1-blockade worsens heart failure in hypertension and does not improve outcomes in heart failure, implying a cardioprotective role for human alpha1-ARs. In summary, these findings identify novel functional and mechanistic aspects of cardiac alpha1-AR function and suggest that activation of cardiac alpha1-AR might be a viable therapeutic strategy in heart failure. PMID:24368739

  10. Toxicological Differences Between NMDA Receptor Antagonists and Cholinesterase Inhibitors.

    PubMed

    Shi, Xiaodong; Lin, Xiaotian; Hu, Rui; Sun, Nan; Hao, Jingru; Gao, Can

    2016-08-01

    Cholinesterase inhibitors (ChEIs), represented by donepezil, rivastigmine, and galantamine, used to be the only approved class of drugs for the treatment of Alzheimer's disease. After the approval of memantine by the Food and Drug Administration (FDA), N-methyl-d-aspartic acid (NMDA) receptor antagonists have been recognized by authorities and broadly used in the treatment of Alzheimer's disease. Along with complementary mechanisms of action, NMDA antagonists and ChEIs differ not only in therapeutic effects but also in adverse reactions, which is an important consideration in clinical drug use. And the number of patients using NMDA antagonists and ChEIs concomitantly has increased, making the matter more complicated. Here we used the FDA Adverse Event Reporting System for statistical analysis , in order to compare the adverse events of memantine and ChEIs. In general, the clinical evidence confirmed the safety advantages of memantine over ChEIs, reiterating the precautions of clinical drug use and the future direction of antidementia drug development. PMID:26769920

  11. Dihydromunduletone Is a Small-Molecule Selective Adhesion G Protein-Coupled Receptor Antagonist.

    PubMed

    Stoveken, Hannah M; Bahr, Laura L; Anders, M W; Wojtovich, Andrew P; Smrcka, Alan V; Tall, Gregory G

    2016-09-01

    Adhesion G protein-coupled receptors (aGPCRs) have emerging roles in development and tissue maintenance and is the most prevalent GPCR subclass mutated in human cancers, but to date, no drugs have been developed to target them in any disease. aGPCR extracellular domains contain a conserved subdomain that mediates self-cleavage proximal to the start of the 7-transmembrane domain (7TM). The two receptor protomers, extracellular domain and amino terminal fragment (NTF), and the 7TM or C-terminal fragment remain noncovalently bound at the plasma membrane in a low-activity state. We recently demonstrated that NTF dissociation liberates the 7TM N-terminal stalk, which acts as a tethered-peptide agonist permitting receptor-dependent heterotrimeric G protein activation. In many cases, natural aGPCR ligands are extracellular matrix proteins that dissociate the NTF to reveal the tethered agonist. Given the perceived difficulty in modifying extracellular matrix proteins to create aGPCR probes, we developed a serum response element (SRE)-luciferase-based screening approach to identify GPR56/ADGRG1 small-molecule inhibitors. A 2000-compound library comprising known drugs and natural products was screened for GPR56-dependent SRE activation inhibitors that did not inhibit constitutively active Gα13-dependent SRE activation. Dihydromunduletone (DHM), a rotenoid derivative, was validated using cell-free aGPCR/heterotrimeric G protein guanosine 5'-3-O-(thio)triphosphate binding reconstitution assays. DHM inhibited GPR56 and GPR114/ADGRG5, which have similar tethered agonists, but not the aGPCR GPR110/ADGRF1, M3 muscarinic acetylcholine, or β2 adrenergic GPCRs. DHM inhibited tethered peptide agonist-stimulated and synthetic peptide agonist-stimulated GPR56 but did not inhibit basal activity, demonstrating that it antagonizes the peptide agonist. DHM is a novel aGPCR antagonist and potentially useful chemical probe that may be developed as a future aGPCR therapeutic. PMID:27338081

  12. Adrenergic and serotonin receptors affect retinal superoxide generation in diabetic mice: relationship to capillary degeneration and permeability.

    PubMed

    Du, Yunpeng; Cramer, Megan; Lee, Chieh Allen; Tang, Jie; Muthusamy, Arivalagan; Antonetti, David A; Jin, Hui; Palczewski, Krzysztof; Kern, Timothy S

    2015-05-01

    Reactive oxygen species play an important role in the pathogenesis of diabetic retinopathy. We studied the role of adrenergic and serotonin receptors in the generation of superoxide by retina and 661W retinal cells in high glucose and of the α1-adrenergic receptor (AR) on vascular lesions of the retinopathy in experimentally diabetic C57Bl/6J mice (and controls) after 2 and 8 months. Compared with 5 mM glucose, incubating cells or retinal explants in 30 mM glucose induced superoxide generation. This response was reduced or ablated by pharmacologic inhibition of the α1-AR (a Gq-coupled receptor) or Gs-coupled serotonin (5-HT2, 5-HT4, 5-HT6, and 5-HT7) receptors or by activation of the Gi-coupled α2-AR. In elevated glucose, the α1-AR produced superoxide via phospholipase C, inositol triphosphate-induced Ca(2+) release, and NADPH oxidase, and pharmacologic inhibition of these reactions prevented the superoxide increase. Generation of retinal superoxide, expression of proinflammatory proteins, and degeneration of retinal capillaries in diabetes all were significantly inhibited with daily doxazosin or apocynin (inhibitors of α1-AR and NADPH oxidase, respectively), but increased vascular permeability was not significantly affected. Adrenergic receptors, and perhaps other GPCRs, represent novel targets for inhibiting the development of important features of diabetic retinopathy. PMID:25667222

  13. Adrenergic and serotonin receptors affect retinal superoxide generation in diabetic mice: relationship to capillary degeneration and permeability

    PubMed Central

    Du, Yunpeng; Cramer, Megan; Lee, Chieh Allen; Tang, Jie; Muthusamy, Arivalagan; Antonetti, David A.; Jin, Hui; Palczewski, Krzysztof; Kern, Timothy S.

    2015-01-01

    Reactive oxygen species play an important role in the pathogenesis of diabetic retinopathy. We studied the role of adrenergic and serotonin receptors in the generation of superoxide by retina and 661W retinal cells in high glucose and of the α1-adrenergic receptor (AR) on vascular lesions of the retinopathy in experimentally diabetic C57Bl/6J mice (and controls) after 2 and 8 months. Compared with 5 mM glucose, incubating cells or retinal explants in 30 mM glucose induced superoxide generation. This response was reduced or ablated by pharmacologic inhibition of the α1-AR (a Gq-coupled receptor) or Gs-coupled serotonin (5-HT2, 5-HT4, 5-HT6, and 5-HT7) receptors or by activation of the Gi-coupled α2-AR. In elevated glucose, the α1-AR produced superoxide via phospholipase C, inositol triphosphate-induced Ca2+ release, and NADPH oxidase, and pharmacologic inhibition of these reactions prevented the superoxide increase. Generation of retinal superoxide, expression of proinflammatory proteins, and degeneration of retinal capillaries in diabetes all were significantly inhibited with daily doxazosin or apocynin (inhibitors of α1-AR and NADPH oxidase, respectively), but increased vascular permeability was not significantly affected. Adrenergic receptors, and perhaps other GPCRs, represent novel targets for inhibiting the development of important features of diabetic retinopathy.—Du, Y., Cramer, M., Lee, C. A., Tang, J., Muthusamy, A., Antonetti, D. A., Jin, H., Palczewski, K., Kern, T. S. Adrenergic and serotonin receptors affect retinal superoxide generation in diabetic mice: relationship to capillary degeneration and permeability. PMID:25667222

  14. Interleukin-1 receptor antagonist gene therapy for arthritis.

    PubMed

    Krishnan, B R

    1999-08-01

    Rheumtatoid arthritis (RA) is a crippling, autoimmune disease, and is characterized by inflammation and destruction of joint tissue. Interleukin-1 (IL-1) has been identified as a key pro-inflammatory cytokine responsible for inflammation. One of the mechanisms of regulation of activity of IL-1 is IL-1 receptor antagonist (IL-1ra)-mediated: IL-1RA competes with IL-1 for binding to the IL-1 receptor. Significant progress has been made in the potential application of IL-1ra gene therapyfor the treatment of arthritis. Various vectors have been tested for the delivery of the IL-1ra gene to the intra-articular region. Recent studies in humans have provided encouraging prospects for IL-1ra-mediated arthritis gene therapy. PMID:11713759

  15. Neurokinin-1 Receptor Antagonists in Preventing Postoperative Nausea and Vomiting

    PubMed Central

    Liu, Meng; Zhang, Hao; Du, Bo-Xiang; Xu, Feng-Ying; Zou, Zui; Sui, Bo; Shi, Xue-Yin

    2015-01-01

    Abstract Newly developed neurokinin-1 receptor (NK-1R) antagonists have been recently tried in the prevention of postoperative nausea and vomiting (PONV). This systematic review and meta-analysis was conducted to explore whether NK-1R antagonists were effective in preventing PONV. The PRISMA statement guidelines were followed. Randomized clinical trials (RCTs) that tested the preventive effects of NK-1R antagonists on PONV were identified by searching EMBASE, CINAHL, PubMed, and the Cochrane Library databases followed by screening. Data extraction was performed using a predefined form and trial quality was assessed using a modified Jadad scale. The primary outcome measure was the incidence of PONV. Meta-analysis was performed for studies using similar interventions. Network meta-analysis (NMA) was conducted to compare the anti-vomiting effects of placebo, ondansetron, and aprepitant at different doses. Fourteen RCTs were included. Meta-analysis found that 80 mg of aprepitant could reduce the incidences of nausea (3 RCTs with 224 patients, pooled risk ratio (RR) = 0.60, 95% confidence interval (CI) = 0.47 to 0.75), and vomiting (3 RCTs with 224 patients, pooled RR = 0.13, 95% CI = 0.04 to 0.37) compared with placebo. Neither 40 mg (3 RCTs with 1171 patients, RR = 0.47, 95% CI = 0.37 to 0.60) nor 125 mg (2 RCTs with 1058 patients, RR = 0.32, 95% CI = 0.13 to 0.78) of aprepitant showed superiority over 4 mg of ondansetron in preventing postoperative vomiting. NMA did not find a dose-dependent effect of aprepitant on preventing postoperative vomiting. Limited data suggested that NK-1R antagonists, especially aprepitant were effective in preventing PONV compared with placebo. More large-sampled high-quality RCTs are needed. PMID:25984662

  16. Inhibition of Brain Swelling after Ischemia-Reperfusion by β-Adrenergic Antagonists: Correlation with Increased K+ and Decreased Ca2+ Concentrations in Extracellular Fluid

    PubMed Central

    Xu, Junnan; Du, Ting; Yan, Enzhi; Walz, Wolfgang; Peng, Liang

    2014-01-01

    Infarct size and brain edema following ischemia/reperfusion are reduced by inhibitors of the Na+, K+, 2Cl−, and water cotransporter NKCC1 and by β1-adrenoceptor antagonists. NKCC1 is a secondary active transporter, mainly localized in astrocytes, driven by transmembrane Na+/K+ gradients generated by the Na+,K+-ATPase. The astrocytic Na+,K+-ATPase is stimulated by small increases in extracellular K+ concentration and by the β-adrenergic agonist isoproterenol. Larger K+ increases, as occurring during ischemia, also stimulate NKCC1, creating cell swelling. This study showed no edema after 3 hr medial cerebral artery occlusion but pronounced edema after 8 hr reperfusion. The edema was abolished by inhibitors of specifically β1-adrenergic pathways, indicating failure of K+-mediated, but not β1-adrenoceptor-mediated, stimulation of Na+,K+-ATPase/NKCC1 transport during reoxygenation. Ninety percent reduction of extracellular Ca2+ concentration occurs in ischemia. Ca2+ omission abolished K+ uptake in normoxic cultures of astrocytes after addition of 5 mM KCl. A large decrease in ouabain potency on K+ uptake in cultured astrocytes was also demonstrated in Ca2+-depleted media, and endogenous ouabains are needed for astrocytic K+ uptake. Thus, among the ionic changes induced by ischemia, the decrease in extracellular Ca2+ causes failure of the high-K+-stimulated Na+,K+-ATPase/NKCC1 ion/water uptake, making β1-adrenergic activation the only stimulus and its inhibition effective against edema. PMID:25478577

  17. Backbone NMR reveals allosteric signal transduction networks in the β1-adrenergic receptor.

    PubMed

    Isogai, Shin; Deupi, Xavier; Opitz, Christian; Heydenreich, Franziska M; Tsai, Ching-Ju; Brueckner, Florian; Schertler, Gebhard F X; Veprintsev, Dmitry B; Grzesiek, Stephan

    2016-02-11

    G protein-coupled receptors (GPCRs) are physiologically important transmembrane signalling proteins that trigger intracellular responses upon binding of extracellular ligands. Despite recent breakthroughs in GPCR crystallography, the details of ligand-induced signal transduction are not well understood owing to missing dynamical information. In principle, such information can be provided by NMR, but so far only limited data of functional relevance on few side-chain sites of eukaryotic GPCRs have been obtained. Here we show that receptor motions can be followed at virtually any backbone site in a thermostabilized mutant of the turkey β1-adrenergic receptor (β1AR). Labelling with [(15)N]valine in a eukaryotic expression system provides over twenty resolved resonances that report on structure and dynamics in six ligand complexes and the apo form. The response to the various ligands is heterogeneous in the vicinity of the binding pocket, but gets transformed into a homogeneous readout at the intracellular side of helix 5 (TM5), which correlates linearly with ligand efficacy for the G protein pathway. The effect of several pertinent, thermostabilizing point mutations was assessed by reverting them to the native sequence. Whereas the response to ligands remains largely unchanged, binding of the G protein mimetic nanobody NB80 and G protein activation are only observed when two conserved tyrosines (Y227 and Y343) are restored. Binding of NB80 leads to very strong spectral changes throughout the receptor, including the extracellular ligand entrance pocket. This indicates that even the fully thermostabilized receptor undergoes activating motions in TM5, but that the fully active state is only reached in presence of Y227 and Y343 by stabilization with a G protein-like partner. The combined analysis of chemical shift changes from the point mutations and ligand responses identifies crucial connections in the allosteric activation pathway, and presents a general experimental

  18. Regulation of β2-Adrenergic Receptor Maturation and Anterograde Trafficking by an Interaction with Rab Geranylgeranyltransferase

    PubMed Central

    Lachance, Véronik; Cartier, Andréane; Génier, Samuel; Munger, Sandra; Germain, Pascale; Labrecque, Pascale; Parent, Jean-Luc

    2011-01-01

    Previous reports by us and others demonstrated that G protein-coupled receptors interact functionally with Rab GTPases. Here, we show that the β2-adrenergic receptor (β2AR) interacts with the Rab geranylgeranyltransferase α-subunit (RGGTA). Confocal microscopy showed that β2AR co-localizes with RGGTA in intracellular compartments and at the plasma membrane. Site-directed mutagenesis revealed that RGGTA binds to the L339L340 motif in the β2AR C terminus known to be involved in the transport of the receptor from the endoplasmic reticulum to the cell surface. Modulation of the cellular levels of RGGTA protein by overexpression or siRNA-mediated knockdown of the endogenous protein demonstrated that RGGTA has a positive role in the maturation and anterograde trafficking of the β2AR, which requires the interaction of RGGTA with the β2AR L339L340 motif. Furthermore, the β2AR modulates the geranylgeranylation of Rab6a, Rab8a, and Rab11a, but not of other Rab proteins tested in this study. Regulation of Rab geranylgeranylation by the β2AR was dependent on the RGGTA-interacting L339L340 motif. Interestingly, a RGGTA-Y107F mutant was unable to regulate Rab geranylgeranylation but still promoted β2AR maturation, suggesting that RGGTA may have functions independent of Rab geranylgeranylation. We demonstrate for the first time an interaction between a transmembrane receptor and RGGTA which regulates the maturation and anterograde transport of the receptor, as well as geranylgeranylation of Rab GTPases. PMID:21990357

  19. Targeting ß2 adrenergic receptors regulate human T cell function directly and indirectly.

    PubMed

    Zalli, A; Bosch, J A; Goodyear, O; Riddell, N; McGettrick, H M; Moss, P; Wallace, G R

    2015-03-01

    It is well-established that central nervous system activation affects peripheral blood mononuclear cell (PBMCs) function through the release of the catecholamines (Epi) and norepinephrine (NE), which act on ß2-adrenergic receptors (ß2AR). However, most studies have used non-specific stimulation of cells rather than antigen-specific responses. Likewise, few studies have parsed out the direct effects of ß2AR stimulation on T cells versus indirect effects via adrenergic stimulation of antigen presenting cells (APC). Here we report the effect of salmeterol (Sal), a selective ß2AR agonist, on IFN-γ(+) CD4 and IFN-γ(+) CD8 T cells following stimulation with Cytomegalovirus lysate (CMVL-strain AD169) or individual peptides spanning the entire region of the HCMV pp65 protein (pp65). Cells were also stimulated with Staphylococcal enterotoxin B. Additionally, we investigated the effect of Epi and Sal on cytotoxic cell killing of transfected target cells at the single cell level using the CD107a assay. The results show that Sal reduced the percentage of IFN-γ(+) CD4 and IFN-γ(+) CD8 T cells both when applied directly to isolated T cells, and indirectly via treatment of APC. These inhibitory effects were mediated via a ß2 adrenergic-dependent pathway and were stronger for CD8 as compared to CD4 T cells. Similarly, the results show that Sal suppressed cytotoxicity of both CD8 T and NK cells in vitro following stimulation with Chinese hamster ovary cell line transfected with MICA(*009) (T-CHO) and the human erythromyeloblastoid leukemic (K562) cell line. The inhibitory effect on cytotoxicity following stimulation with T-CHO was stronger in NK cells compared with CD8 T cells. Thus, targeting the ß2AR on lymphocytes and on APC leads to inhibition of inflammatory cytokine production and target cell killing. Moreover, there is a hierarchy of responses, with CD8 T cells and NK cells inhibited more effectively than CD4 T cells. PMID:25526818

  20. Evodiamine as a novel antagonist of aryl hydrocarbon receptor

    SciTech Connect

    Yu, Hui; Tu, Yongjiu; Zhang, Chun; Fan, Xia; Wang, Xi; Wang, Zhanli; Liang, Huaping

    2010-11-05

    Research highlights: {yields} Evodiamine interacted with the AhR. {yields} Evodiamine inhibited the specific binding of [{sup 3}H]-TCDD to the AhR. {yields} Evodiamine acts as an antagonist of the AhR. -- Abstract: Evodiamine, the major bioactive alkaloid isolated from Wu-Chu-Yu, has been shown to interact with a wide variety of proteins and modify their expression and activities. In this study, we investigated the interaction between evodiamine and the aryl hydrocarbon receptor (AhR). Molecular modeling results revealed that evodiamine directly interacted with the AhR. Cytosolic receptor binding assay also provided the evidence that evodiamine could interact with the AhR with the K{sub i} value of 28.4 {+-} 4.9 nM. In addition, we observed that evodiamine suppressed the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced nuclear translocation of the AhR and the expression of CYP1A1 dose-dependently. These results suggested that evodiamine was able to bind to the AhR as ligand and exhibit antagonistic effects.

  1. 3D pharmacophore models for thromboxane A(2) receptor antagonists.

    PubMed

    Wei, Jing; Liu, Yixi; Wang, Songqing

    2009-10-01

    Thromboxane A(2) (TXA(2)) is an endogenous arachidonic acid derivative closely correlated to thrombosis and other cardiovascular diseases. The action of TXA(2) can be effectively inhibited with TXA(2) receptor antagonists (TXRAs). Previous studies have attempted to describe the interactions between the TXA(2) receptor and its ligands, but their conclusions are still controversial. In this study, ligand-based computational drug design is used as a new and effective way to investigate the structure-activity relationship of TXRAs. Three-dimensional pharmacophore models of TXRAs were built with HypoGenRefine and HipHop modules in CATALYST software. The optimal HypoGenRefine model was developed on the basis of 25 TXRAs. It consists of two hydrophobic groups, one aromatic ring, one hydrogen-bond acceptor and four excluded volumes. The optimal HipHop model contains two hydrophobic groups and two hydrogen-bond acceptors. These models describe the key structure-activity relationship of TXRAs, can predict their activities, and can thus be used to design novel antagonists. PMID:19263096

  2. Curcumin pretreatment mediates antidiabetogenesis via functional regulation of adrenergic receptor subtypes in the pancreas of multiple low-dose streptozotocin-induced diabetic rats.

    PubMed

    Naijil, George; Anju, T R; Jayanarayanan, S; Paulose, C S

    2015-09-01

    Lifestyle modification pivoting on nutritional management holds tremendous potential to meet the challenge of management of diabetes. The current study hypothesizes that regular uptake of curcumin lowers the incidence of diabetes by functional regulation of pancreatic adrenergic receptor subtypes. The specific objective of the study was to identify the regulatory pathways implicated in the antidiabetogenesis effect of curcumin in multiple low-dose streptozotocin (MLD-STZ)-induced diabetic Wistar rats. Administration of MLD-STZ to curcumin-pretreated rats induced a prediabetic condition. Scatchard analysis, real-time polymerase chain reaction, and confocal microscopic studies confirmed a significant increase in α2-adrenergic receptor expression in the pancreas of diabetic rats. Pretreatment with curcumin significantly decreased α2-adrenergic receptor expression. The diabetic group showed a significant decrease in the expression of β-adrenergic receptors when compared with control. Pretreatment significantly increased β-adrenergic receptor expression to near control. When compared with the diabetic rats, a significant up-regulation of CREB, phospholipase C, insulin receptor, and glucose transporter 2 were observed in the pretreated group. Curcumin pretreatment was also able to maintain near control levels of cyclic adenosine monophosphate, cyclic guanosine monophosphate, and inositol triphosphate. These results indicate that a marked decline in α2-adrenergic receptor function relents sympathetic inhibition of insulin release. It also follows that escalated signaling through β-adrenergic receptors mediates neuronal stimulation of hyperglycemia-induced β-cell compensatory response. Curcumin-mediated functional regulation of adrenergic receptors and modulation of key cell signaling molecules improve pancreatic glucose sensing, insulin gene expression, and insulin secretion. PMID:26255758

  3. Molecular modelling of human 5-hydroxytryptamine receptor (5-HT2A) and virtual screening studies towards the identification of agonist and antagonist molecules.

    PubMed

    Gandhimathi, A; Sowdhamini, R

    2016-05-01

    The serotonin receptors, also known as 5-hydroxytryptamine (5-HT) receptors, are a group of G protein-coupled receptors (GPCRs) and ligand-gated ion channels found in the central and peripheral nervous systems. GPCRs have a characteristic feature of activating different signalling pathways upon ligand binding and these ligands display several efficacy levels to differentially activate the receptor. GPCRs are primary drug targets due to their central role in several signal transduction pathways. Drug design for GPCRs is also most challenging due to their inherent promiscuity in ligand recognition, which gives rise to several side effects of existing drugs. Here, we have performed the ligand interaction study using the two prominent states of GPCR, namely the active and inactive state of the 5-HT2A receptor. Active state of 5-HT2A receptor model enhances the understanding of conformational difference which influences the ligand-binding site. A 5-HT2A receptor active state model was constructed by homology modelling using active state β2-adrenergic receptor (β2-AR). In addition, virtual screening and docking studies with both active and inactive state models reveal potential small molecule hits which could be considered as agonist-like and antagonist-like molecules. The results from the all-atom molecular dynamics simulations further confirmed that agonists and antagonists interact in different modes with the receptor. PMID:26327576

  4. The α2B adrenergic receptor is mutant in cortical myoclonus and epilepsy

    PubMed Central

    De Fusco, Maurizio; Vago, Riccardo; Striano, Pasquale; Di Bonaventura, Carlo; Zara, Federico; Mei, Davide; Kim, Min Seuk; Muallem, Shmuel; Chen, Yunjia; Wang, Qin; Guerrini, Renzo; Casari, Giorgio

    2013-01-01

    Objective Autosomal dominant cortical myoclonus and epilepsy (ADCME) is characterized by distal, fairly rhythmic myoclonus and epilepsy with variable severity. We have previously mapped the disease locus on chromosome 2p11.1-q12.2 by genome-wide linkage analysis. Additional pedigrees affected by similar forms of epilepsy have been associated to chromosome 8q, 5p and 3q, but none of the causing genes has been identified. We aim at identifying the mutant gene responsible for this epileptic form. Methods Genes included in the ADCME critical region were prioritized and directly sequenced. Co-immunoprecipitation, immunofluorescence and electrophysiology approaches on transfected human cells have been utilized for testing the functional significance of the identified mutation. Results Here we show that mutation in the α2-adrenergic receptor subtype B (α2B-AR) associates to ADCME by identifying a novel in-frame insertion/deletion in two Italian families. The mutation alters several conserved residues of the third intracellular (3i) loop, neither hampering the α2B-AR plasma membrane localization nor the arrestin-mediated internalization capacity, but altering the binding with the scaffolding protein spinophilin upon neurotransmitter activation. Spinophilin, in turn, regulates interaction of GPCRs with Regulators of G proteins Signaling proteins. Accordingly, the mutant α2B-AR increases the epinephrine-stimulated calcium signaling. Interpretation The identified mutation is responsible for ADCME, as the loss of α2B-AR/spinophilin interaction causes a gain of function effect. This work implicates for the first time the α-adrenergic system in human epilepsy and opens new ways for understanding the molecular pathway of epileptogenesis, widening the spectrum of possible therapeutic targets. PMID:24114805

  5. Leukocyte beta-adrenergic receptor sensitivity and depression severity in patients with heart failure

    PubMed Central

    Redwine, Laura S.; Hong, Suzi; Rutledge, Thomas; Wentworth, Bailey; Pung, Meredith; Ziegler, Michael G.; Maisel, Alan; Greenberg, Barry; Mills, Paul J.

    2016-01-01

    Objectives Clinical outcomes are worse for patients with heart failure (HF) and elevated depression symptoms. Depression related sympatho-immune dysregulation may be one mechanism leading to poorer HF prognosis. Sympathetically mediated adrenergic activity is known to regulate immune activity via β-adrenergic receptors (β-ARs). However, studies show conflicting relationships between leukocyte β-AR sensitivity and depression symptoms. The aim of this study was to determine in patients with HF the relationship of leukocyte β-AR sensitivity with two diverse measures of depression, self-report questionnaire versus clinical diagnostic interview. Methods Patients with HF (N=73, mean age = 56.3, S.D. = 13.0) completed the Beck Depression Inventory −1A (BDI) and a modified Structured Clinical Interview for the DSM-IV (SCID). Leukocyte β-AR sensitivity was determined from isoproterenol stimulated cyclic AMP levels; plasma norepinephrine and epinephrine were also assessed. Results Patients with major depression determined by SCID had significantly higher β-AR sensitivity than non-depressed (F(6, 72) = 9.27, p = .003, η2 = .12). Meanwhile, the BDI revealed a more complex relationship. Minimal, mild, and moderate-to-severe depression symptom groups had significant differences in β-AR sensitivity (F(7, 72) = 7.03, p = .002, η2 = .18), with mild symptoms appearing to correspond with reduced β-AR sensitivity and moderate-to-severe symptoms with higher β-AR sensitivity. Conclusions By deconstructing depression measurements a greater depth of information may be garnered to potentially reveal subtypes of depression symptoms and their relation to β-AR sensitivity in HF. PMID:25373889

  6. The contribution of IL-6 to beta 3 adrenergic receptor mediated adipose tissue remodeling.

    PubMed

    Buzelle, Samyra L; MacPherson, Rebecca E K; Peppler, Willem T; Castellani, Laura; Wright, David C

    2015-02-01

    The chronic activation of beta 3 adrenergic receptors results in marked alterations in adipose tissue morphology and metabolism, including increases in mitochondrial content and the expression of enzymes involved in lipogenesis and glyceroneogenesis. Acute treatment with CL 316,243, a beta 3 adrenergic agonist, induces the expression of interleukin 6. Interestingly, IL-6 has been shown to induce mitochondrial genes in cultured adipocytes. Therefore, the purpose of this paper was to examine the role of interleukin 6 in mediating the in vivo effects of CL 316,243 in white adipose tissue. Circulating IL-6, and markers of IL-6 signaling in white adipose tissue were increased 4 h following a single injection of CL 316,243 in C57BL6/J mice. Once daily injections of CL 316,243 for 5 days increased the protein content of a number of mitochondrial proteins including CORE1, Cytochrome C, PDH, MCAD, and Citrate Synthase to a similar extent in adipose tissue from WT and IL-6(-/-) mice. Conversely, CL 316,243-induced increases in COXIV and phosphorylated AMPK were attenuated in IL-6(-/-) mice. Likewise, the slight, but significant, CL 316,243-induced increases in ATGL, PEPCK, and PPARγ, were reduced or absent in adipose tissue IL-6(-/-) mice. The attenuated response to CL 316,243 in white adipose tissue in IL-6(-/-) mice was associated with reductions in whole-body oxygen consumption and energy expenditure in the light phase. Our findings suggest that IL-6 plays a limited role in CL 316,243-mediated adipose tissue remodeling. PMID:25713332

  7. Induction of M2 regulatory macrophages through the β2 adrenergic receptor with protection during endotoxemia and acute lung injury

    PubMed Central

    Grailer, Jamison J.; Haggadone, Mikel D.; Sarma, J. Vidya; Zetoune, Firas S.; Ward, Peter A.

    2014-01-01

    Main drivers of acute inflammation are macrophages, which are known to have receptors for catecholamines. Based on their function, macrophages are broadly categorized as either M1 (pro-inflammatory) or M2 phenotypes (anti-inflammatory). In this study, we investigated catecholamine-induced alterations in the phenotype of activated macrophages. In the presence of lipopolysaccharide (LPS), mouse peritoneal macrophages acquired an M1 phenotype. However, the co-presence of LPS and either epinephrine or norepinephrine resulted in a strong M2 phenotype including high levels of arginase-1 and interleukin (IL) -10, and reduced expression of M1 markers. Furthermore, epinephrine enhanced macrophage phagocytosis and promoted type 2 T cell responses in vitro, which are known features of M2 macrophages. Analysis of M2 subtype-specific markers indicated that LPS and catecholamine co-treated macrophages were not alternatively activated, but of the regulatory macrophage subtype. Interestingly, catecholamines signaled through the β2 adrenergic receptor, but not the canonical cAMP/protein kinase A signaling pathway. Instead, the M2 pathway required an intact phosphoinositol 3-kinase pathway. Blockade of the β2 adrenergic receptor reduced survival and enhanced injury during mouse models of endotoxemia and LPS-induced acute lung injury, respectively. These results demonstrate a role for the β2 adrenergic receptor in promoting the M2 macrophage phenotype. PMID:24642449

  8. Differential effect of glucocorticoid receptor antagonists on glucocorticoid receptor nuclear translocation and DNA binding

    PubMed Central

    Spiga, Francesca; Knight, David M; Droste, Susanne K; Conway-Campbell, Becky; Kershaw, Yvonne; MacSweeney, Cliona P; Thomson, Fiona J; Craighead, Mark; Peeters, Bernard WMM; Lightman, Stafford L

    2016-01-01

    The effects of RU486 and S-P, a more selective glucocorticoid receptor antagonist from Schering-Plough, were investigated on glucocorticoid receptor nuclear translocation and DNA binding. In the in vitro study, AtT20 cells were treated with vehicle or with RU486, S-P or corticosterone (3–300 nM) or co-treated with vehicle or glucocorticoid receptor antagonists (3–300 nM) and 30 nM corticosterone. Both glucocorticoid receptor antagonists induced glucocorticoid receptor nuclear translocation but only RU486 induced DNA binding. RU486 potentiated the effect of corticosterone on glucocorticoid receptor nuclear translocation and DNA binding, S-P inhibited corticosterone-induced glucocorticoid receptor nuclear translocation, but not glucocorticoid receptor-DNA binding. In the in vivo study, adrenalectomized rats were treated with vehicle, RU486 (20 mg/kg) and S-P (50 mg/kg) alone or in combination with corticosterone (3 mg/kg). RU486 induced glucocorticoid receptor nuclear translocation in the pituitary, hippocampus and prefrontal cortex and glucocorticoid receptor-DNA binding in the hippocampus, whereas no effect of S-P on glucocorticoid receptor nuclear translocation or DNA binding was observed in any of the areas analysed. These findings reveal differential effects of RU486 and S-P on areas involved in regulation of hypothalamic–pituitary–adrenal axis activity in vivo and they are important in light of the potential use of this class of compounds in the treatment of disorders associated with hyperactivity of the hypothalamic–pituitary–adrenal axis. PMID:20093322

  9. BRET evidence that β2 adrenergic receptors do not oligomerize in cells

    PubMed Central

    Lan, Tien-Hung; Liu, Qiuju; Li, Chunman; Wu, Guangyu; Steyaert, Jan; Lambert, Nevin A.

    2015-01-01

    Bioluminescence resonance energy transfer (BRET) is often used to study association of membrane proteins, and in particular oligomerization of G protein-coupled receptors (GPCRs). Oligomerization of class A GPCRs is controversial, in part because the methods used to study this question are not completely understood. Here we reconsider oligomerization of the class A β2 adrenergic receptor (β2AR), and reevaluate BRET titration as a method to study membrane protein association. Using inducible expression of the energy acceptor at multiple levels of donor expression we find that BRET between β2AR protomers is directly proportional to the density of the acceptor up to ~3,000 acceptors μm−2, and does not depend on the density of the donor or on the acceptor:donor (A:D) stoichiometry. In contrast, BRET between tightly-associating control proteins does not depend on the density of the acceptor, but does depend on the density of the donor and on the A:D ratio. We also find that the standard frameworks used to interpret BRET titration experiments rely on simplifying assumptions that are frequently invalid. These results suggest that β2ARs do not oligomerize in cells, and demonstrate a reliable method of assessing membrane protein association with BRET. PMID:25955971

  10. In vivo phosphoproteomics analysis reveals the cardiac targets of β-adrenergic receptor signaling.

    PubMed

    Lundby, Alicia; Andersen, Martin N; Steffensen, Annette B; Horn, Heiko; Kelstrup, Christian D; Francavilla, Chiara; Jensen, Lars J; Schmitt, Nicole; Thomsen, Morten B; Olsen, Jesper V

    2013-06-01

    β-Blockers are widely used to prevent cardiac arrhythmias and to treat hypertension by inhibiting β-adrenergic receptors (βARs) and thus decreasing contractility and heart rate. βARs initiate phosphorylation-dependent signaling cascades, but only a small number of the target proteins are known. We used quantitative in vivo phosphoproteomics to identify 670 site-specific phosphorylation changes in murine hearts in response to acute treatment with specific βAR agonists. The residues adjacent to the regulated phosphorylation sites exhibited a sequence-specific preference (R-X-X-pS/T), and integrative analysis of sequence motifs and interaction networks suggested that the kinases AMPK (adenosine 5'-monophosphate-activated protein kinase), Akt, and mTOR (mammalian target of rapamycin) mediate βAR signaling, in addition to the well-established pathways mediated by PKA (cyclic adenosine monophosphate-dependent protein kinase) and CaMKII (calcium/calmodulin-dependent protein kinase type II). We found specific regulation of phosphorylation sites on six ion channels and transporters that mediate increased ion fluxes at higher heart rates, and we showed that phosphorylation of one of these, Ser(92) of the potassium channel KV7.1, increased current amplitude. Our data set represents a quantitative analysis of phosphorylated proteins regulated in vivo upon stimulation of seven-transmembrane receptors, and our findings reveal previously unknown phosphorylation sites that regulate myocardial contractility, suggesting new potential targets for the treatment of heart disease and hypertension. PMID:23737553

  11. Phosphorylation of Src by phosphoinositide 3-kinase regulates beta-adrenergic receptor-mediated EGFR transactivation.

    PubMed

    Watson, Lewis J; Alexander, Kevin M; Mohan, Maradumane L; Bowman, Amber L; Mangmool, Supachoke; Xiao, Kunhong; Naga Prasad, Sathyamangla V; Rockman, Howard A

    2016-10-01

    β2-Adrenergic receptors (β2AR) transactivate epidermal growth factor receptors (EGFR) through formation of a β2AR-EGFR complex that requires activation of Src to mediate signaling. Here, we show that both lipid and protein kinase activities of the bifunctional phosphoinositide 3-kinase (PI3K) enzyme are required for β2AR-stimulated EGFR transactivation. Mechanistically, the generation of phosphatidylinositol (3,4,5)-tris-phosphate (PIP3) by the lipid kinase function stabilizes β2AR-EGFR complexes while the protein kinase activity of PI3K regulates Src activation by direct phosphorylation. The protein kinase activity of PI3K phosphorylates serine residue 70 on Src to enhance its activity and induce EGFR transactivation following βAR stimulation. This newly identified function for PI3K, whereby Src is a substrate for the protein kinase activity of PI3K, is of importance since Src plays a key role in pathological and physiological signaling. PMID:27169346

  12. β2-Adrenergic receptor agonists activate CFTR in intestinal organoids and subjects with cystic fibrosis.

    PubMed

    Vijftigschild, Lodewijk A W; Berkers, Gitte; Dekkers, Johanna F; Zomer-van Ommen, Domenique D; Matthes, Elizabeth; Kruisselbrink, Evelien; Vonk, Annelotte; Hensen, Chantal E; Heida-Michel, Sabine; Geerdink, Margot; Janssens, Hettie M; van de Graaf, Eduard A; Bronsveld, Inez; de Winter-de Groot, Karin M; Majoor, Christof J; Heijerman, Harry G M; de Jonge, Hugo R; Hanrahan, John W; van der Ent, Cornelis K; Beekman, Jeffrey M

    2016-09-01

    We hypothesized that people with cystic fibrosis (CF) who express CFTR (cystic fibrosis transmembrane conductance regulator) gene mutations associated with residual function may benefit from G-protein coupled receptor (GPCR)-targeting drugs that can activate and enhance CFTR function.We used intestinal organoids to screen a GPCR-modulating compound library and identified β2-adrenergic receptor agonists as the most potent inducers of CFTR function.β2-Agonist-induced organoid swelling correlated with the CFTR genotype, and could be induced in homozygous CFTR-F508del organoids and highly differentiated primary CF airway epithelial cells after rescue of CFTR trafficking by small molecules. The in vivo response to treatment with an oral or inhaled β2-agonist (salbutamol) in CF patients with residual CFTR function was evaluated in a pilot study. 10 subjects with a R117H or A455E mutation were included and showed changes in the nasal potential difference measurement after treatment with oral salbutamol, including a significant improvement of the baseline potential difference of the nasal mucosa (+6.35 mV, p<0.05), suggesting that this treatment might be effective in vivo Furthermore, plasma that was collected after oral salbutamol treatment induced CFTR activation when administered ex vivo to organoids.This proof-of-concept study suggests that organoids can be used to identify drugs that activate CFTR function in vivo and to select route of administration. PMID:27471203

  13. Targeted disruption of the mouse beta1-adrenergic receptor gene: developmental and cardiovascular effects.

    PubMed Central

    Rohrer, D K; Desai, K H; Jasper, J R; Stevens, M E; Regula, D P; Barsh, G S; Bernstein, D; Kobilka, B K

    1996-01-01

    At least three distinct beta-adrenergic receptor (beta-AR) subtypes exist in mammals. These receptors modulate a wide variety of processes, from development and behavior, to cardiac function, metabolism, and smooth muscle tone. To understand the roles that individual beta-AR subtypes play in these processes, we have used the technique of gene targeting to create homozygous beta 1-AR null mutants (beta 1-AR -/-) in mice. The majority of beta 1-AR -/- mice die prenatally, and the penetrance of lethality shows strain dependence. Beta l-AR -/- mice that do survive to adulthood appear normal, but lack the chronotropic and inotropic responses seen in wild-type mice when beta-AR agonists such as isoproterenol are administered. Moreover, this lack of responsiveness is accompanied by markedly reduced stimulation of adenylate cyclase in cardiac membranes from beta 1-AR -/- mice. These findings occur despite persistent cardiac beta 2-AR expression, demonstrating the importance of beta 1-ARs for proper mouse development and cardiac function, while highlighting functional differences between beta-AR subtypes. Images Fig. 1 Fig. 3 PMID:8693001

  14. Effect of intracellular loop 3 on intrinsic dynamics of human β2-adrenergic receptor

    PubMed Central

    2013-01-01

    Background To understand the effect of the long intracellular loop 3 (ICL3) on the intrinsic dynamics of human β2-adrenergic receptor, molecular dynamics (MD) simulations were performed on two different models, both of which were based on the inactive crystal structure in complex with carazolol (after removal of carazolol and T4-lysozyme). In the so-called loop model, the ICL3 region that is missing in available crystal structures was modeled as an unstructured loop of 32-residues length, whereas in the clipped model, the two open ends were covalently bonded to each other. The latter model without ICL3 was taken as a reference, which has also been commonly used in recent computational studies. Each model was embedded into POPC bilayer membrane with explicit water and subjected to a 1 μs molecular dynamics (MD) simulation at 310 K. Results After around 600 ns, the loop model started a transition to a “very inactive” conformation, which is characterized by a further movement of the intracellular half of transmembrane helix 6 (TM6) towards the receptor core, and a close packing of ICL3 underneath the membrane completely blocking the G-protein’s binding site. Concurrently, the binding site at the extracellular part of the receptor expanded slightly with the Ser207-Asp113 distance increasing to 18 Å from 11 Å, which was further elaborated by docking studies. Conclusions The essential dynamics analysis indicated a strong coupling between the extracellular and intracellular parts of the intact receptor, implicating a functional relevance for allosteric regulation. In contrast, no such transition to the “very inactive” state, nor any structural correlation, was observed in the clipped model without ICL3. Furthermore, elastic network analysis using different conformers for the loop model indicated a consistent picture on the specific ICL3 conformational change being driven by global modes. PMID:24206668

  15. Differential Signaling of the Endogenous Agonists at the β2-Adrenergic Receptor*

    PubMed Central

    Reiner, Susanne; Ambrosio, Manuela; Hoffmann, Carsten; Lohse, Martin J.

    2010-01-01

    The concept of “functional selectivity” or “biased signaling” suggests that a ligand can have distinct efficacies with regard to different signaling pathways. We have investigated the question of whether biased signaling may be related to distinct agonist-induced conformational changes in receptors using the β2-adrenergic receptor (β2AR) and its two endogenous ligands epinephrine and norepinephrine as a model system. Agonist-induced conformational changes were determined in a fluorescently tagged β2AR FRET sensor. In this β2AR sensor, norepinephrine caused signals that amounted to only ≈50% of those induced by epinephrine and the standard “full” agonist isoproterenol. Furthermore, norepinephrine-induced changes in the β2AR FRET sensor were slower than those induced by epinephrine (rate constants, 47 versus 128 ms). A similar partial β2AR activation signal was revealed for the synthetic agonists fenoterol and terbutaline. However, norepinephrine was almost as efficient as epinephrine (and isoproterenol) in causing activation of Gs and adenylyl cyclase. In contrast, fenoterol was quite efficient in triggering β-arrestin2 recruitment to the cell surface and its interaction with β2AR, as well as internalization of the receptors, whereas norepinephrine caused partial and slow changes in these assays. We conclude that partial agonism of norepinephrine at the β2AR is related to the induction of a different active conformation and that this conformation is efficient in signaling to Gs and less efficient in signaling to β-arrestin2. These observations extend the concept of biased signaling to the endogenous agonists of the β2AR and link it to distinct conformational changes in the receptor. PMID:20837485

  16. Antagonists of the Vasopressin V1 Receptor and of the β1-Adrenoceptor Inhibit Cytotoxic Brain Edema in Stroke by Effects on Astrocytes – but the Mechanisms Differ

    PubMed Central

    Hertz, Leif; Xu, Junnan; Chen, Ye; Gibbs, Marie E; Du, Ting; Hertz, Leif; Xu, Junnan; Chen, Ye; Gibbs, Marie E; Du, Ting

    2014-01-01

    Brain edema is a serious complication in ischemic stroke because even relatively small changes in brain volume can compromise cerebral blood flow or result in compression of vital brain structures on account of the fixed volume of the rigid skull. Literature data indicate that administration of either antagonists of the V1 vasopressin (AVP) receptor or the β1-adrenergic receptor are able to reduce edema or infarct size when administered after the onset of ischemia, a key advantage for possible clinical use. The present review discusses possible mechanisms, focusing on the role of NKCC1, an astrocytic cotransporter of Na+, K+, 2Cl- and water and its activation by highly increased extracellular K+ concentrations in the development of cytotoxic cell swelling. However, it also mentions that due to a 3/2 ratio between Na+ release and K+ uptake by the Na+,K+-ATPase driving NKCC1 brain extracellular fluid can become hypertonic, which may facilitate water entry across the blood-brain barrier, essential for development of edema. It shows that brain edema does not develop until during reperfusion, which can be explained by lack of metabolic energy during ischemia. V1 antagonists are likely to protect against cytotoxic edema formation by inhibiting AVP enhancement of NKCC1-mediated uptake of ions and water, whereas β1-adrenergic antagonists prevent edema formation because β1-adrenergic stimulation alone is responsible for stimulation of the Na+,K+-ATPase driving NKCC1, first and foremost due to decrease in extracellular Ca2+ concentration. Inhibition of NKCC1 also has adverse effects, e.g. on memory and the treatment should probably be of shortest possible duration. PMID:25342939

  17. N-Benzylpiperidine Derivatives as α7 Nicotinic Receptor Antagonists.

    PubMed

    Criado, Manuel; Mulet, José; Sala, Francisco; Sala, Salvador; Colmena, Inés; Gandía, Luis; Bautista-Aguilera, Oscar M; Samadi, Abdelouahid; Chioua, Mourad; Marco-Contelles, José

    2016-08-17

    A series of multitarget directed propargylamines, as well as other differently susbstituted piperidines have been screened as potential modulators of neuronal nicotinic acetylcholine receptors (nAChRs). Most of them showed antagonist actions on α7 nAChRs. Especially, compounds 13, 26, and 38 displayed submicromolar IC50 values on homomeric α7 nAChRs, whereas they were less effective on heteromeric α3β4 and α4β2 nAChRs (up to 20-fold higher IC50 values in the case of 13). Antagonism was concentration dependent and noncompetitive, suggesting that these compounds behave as negative allosteric modulators of nAChRs. Upon the study of a series of less complex derivatives, the N-benzylpiperidine motif, common to these compounds, was found to be the main pharmacophoric group. Thus, 2-(1-benzylpiperidin-4-yl)-ethylamine (48) showed an inhibitory potency comparable to the one of the previous compounds and also a clear preference for α7 nAChRs. In a neuroblastoma cell line, representative compounds 13 and 48 also inhibited, in a concentration-dependent manner, cytosolic Ca(2+) signals mediated by nAChRs. Finally, compounds 38 and 13 inhibited 5-HT3A serotonin receptors whereas they had no effect on α1 glycine receptors. Given the multifactorial nature of many pathologies in which nAChRs are involved, these piperidine antagonists could have a therapeutic potential in cases where cholinergic activity has to be negatively modulated. PMID:27254782

  18. Demonstration of a Direct Interaction between β2-Adrenergic Receptor and Insulin Receptor by BRET and Bioinformatics

    PubMed Central

    Mandić, Maja; Drinovec, Luka; Glisic, Sanja; Veljkovic, Nevena; Nøhr, Jane; Vrecl, Milka

    2014-01-01

    Glucose metabolism is under the cooperative regulation of both insulin receptor (IR) and β2-adrenergic receptor (β2AR), which represent the receptor tyrosine kinases (RTKs) and seven transmembrane receptors (7TMRs), respectively. Studies demonstrating cross-talk between these two receptors and their endogenous coexpression have suggested their possible interactions. To evaluate the effect of IR and prospective heteromerization on β2AR properties, we showed that IR coexpression had no effect on the ligand binding properties of β2AR; however, IR reduced β2AR surface expression and accelerated its internalization. Additionally, both receptors displayed a similar distribution pattern with a high degree of colocalization. To test the possible direct interaction between β2AR and IR, we employed quantitative BRET2 saturation and competition assays. Saturation assay data suggested constitutive β2AR and IR homo- and heteromerization. Calculated acceptor/donor (AD50) values as a measure of the relative affinity for homo- and heteromer formation differed among the heteromers that could not be explained by a simple dimer model. In heterologous competition assays, a transient increase in the BRET2 signal with a subsequent hyperbolical decrease was observed, suggesting higher-order heteromer formation. To complement the BRET2 data, we employed the informational spectrum method (ISM), a virtual spectroscopy method to investigate protein-protein interactions. Computational peptide scanning of β2AR and IR identified intracellular domains encompassing residues at the end of the 7th TM domain and C-terminal tail of β2AR and a cytoplasmic part of the IR β chain as prospective interaction domains. ISM further suggested a high probability of heteromer formation and homodimers as basic units engaged in heteromerization. In summary, our data suggest direct interaction and higher-order β2AR:IR oligomer formation, likely comprising heteromers of homodimers. PMID:25401701

  19. Single-molecule imaging reveals the stoichiometry change of β2-adrenergic receptors by a pharmacological biased ligand.

    PubMed

    Sun, Yahong; Li, Nan; Zhang, Mingliang; Zhou, Wei; Yuan, Jinghe; Zhao, Rong; Wu, Jimin; Li, Zijian; Zhang, Youyi; Fang, Xiaohong

    2016-06-01

    The stoichiometry of the β2-adrenergic receptor (β2AR) was determined using single-molecule fluorescence imaging in living cells. The results showed that β2AR mainly existed as monomers under physiological conditions and exhibited β-arrestin-dependent dimerization upon stimulation with the pharmacological biased ligand carvedilol. The association of β2AR dimerization with biased signalling is revealed. PMID:27090587

  20. Expression of α(1)-adrenergic receptors in rat prefrontal cortex: cellular co-localization with 5-HT(2A) receptors.

    PubMed

    Santana, Noemí; Mengod, Guadalupe; Artigas, Francesc

    2013-06-01

    The prefrontal cortex (PFC) is involved in behavioural control and cognitive processes that are altered in schizophrenia. The brainstem monoaminergic systems control PFC function, yet the cells/networks involved are not fully known. Serotonin (5-HT) and norepinephrine (NE) increase PFC neuronal activity through the activation of α(1)-adrenergic receptors (α(1)ARs) and 5-HT(2A) receptors (5-HT(2A)Rs), respectively. Neurochemical and behavioural interactions between these receptors have been reported. Further, classical and atypical antipsychotic drugs share nm in vitro affinity for α(1)ARs while having preferential affinity for D(2) and 5-HT(2A)Rs, respectively. Using double in situ hybridization we examined the cellular expression of α(1)ARs in pyramidal (vGluT1-positive) and GABAergic (GAD(65/67)-positive) neurons in rat PFC and their co-localization with 5-HT(2A)Rs. α(1)ARs are expressed by a high proportion of pyramidal (59-85%) and GABAergic (52-79%) neurons. The expression in pyramidal neurons exhibited a dorsoventral gradient, with a lower percentage of α(1)AR-positive neurons in infralimbic cortex compared to anterior cingulate and prelimbic cortex. The expression of α(1A), α(1B) and α(1D) adrenergic receptors was segregated in different layers and subdivisions. In all them there is a high co-expression with 5-HT(2A)Rs (∼80%). These observations indicate that NE controls the activity of most PFC pyramidal neurons via α(1)ARs, either directly or indirectly, via GABAergic interneurons. Antipsychotic drugs can thus modulate the activity of PFC via α(1)AR blockade. The high co-expression with 5-HT(2A)Rs indicates a convergence of excitatory serotonergic and noradrenergic inputs onto the same neuronal populations. Moreover, atypical antipsychotics may exert a more powerful control of PFC function through the simultaneous blockade of α(1)ARs and 5-HT(2A)Rs. PMID:23195622

  1. HBK-7 - A new xanthone derivative and a 5-HT1A receptor antagonist with antidepressant-like properties.

    PubMed

    Pytka, Karolina; Kazek, Grzegorz; Siwek, Agata; Mordyl, Barbara; Głuch-Lutwin, Monika; Rapacz, Anna; Olczyk, Adrian; Gałuszka, Adam; Waszkielewicz, Anna; Marona, Henryk; Sapa, Jacek; Filipek, Barbara; Zygmunt, Małgorzata

    2016-01-01

    Xanthone derivatives possess many biological properties, including neuroprotective, antioxidant or antidepressant-like. In this study we aimed to investigate antidepressant- and anxiolytic-like properties of a new xanthone derivative - 6-methoxy-4-[4-(2-methoxyphenyl)piperazin-1-yl]-9H-xanthen-9-one (HBK-7), as well as its possible mechanism of action, and the influence on cognitive and motor function. HBK-7 in our earlier studies showed high affinity for serotonergic 5-HT1A receptor. We determined the affinity of HBK-7 for CNS receptors and transporters using radioligand assays and examined its intrinsic activity towards 5-HT1A receptor. We evaluated antidepressant- and anxiolytic-like activity of HBK-7 in the mouse forced swim test, and four-plate test, respectively. We examined the influence on locomotor activity in mice to determine if the effect observed in the forced swim test was specific. We used step-through passive avoidance and rotarod tests to evaluate the influence of HBK-7 on cognitive and motor function, respectively. HBK-7 showed moderate affinity for dopaminergic D2 receptor and very low for serotonergic 5-HT2A, adrenergic α2 receptors, as well as serotonin transporter. Functional studies revealed that HBK-7 was a 5-HT1A receptor antagonist. HBK-7 (10mg/kg) decreased immobility time in the forced swim test. Combined treatment with sub-effective doses of HBK-7 and fluoxetine reduced immobility of mice in the forced swim test. Pretreatment with p-chlorophenylalanine and WAY-100,635 antagonized the antidepressant-like effect of HBK-7. Neither of the treatments influenced locomotor activity of mice. HBK-7 at antidepressant-like dose did not impair memory or motor coordination in mice. We demonstrated that HBK-7 was a 5-HT1A receptor antagonist with potent, comparable to mianserin, antidepressant-like activity. HBK-7 mediated its effect through serotonergic system and its antidepressant-like action required the activation of 5-HT1A receptors. At active

  2. Species differences in myocardial beta-adrenergic receptor regulation in response to hyperthyroidism.

    PubMed

    Crozatier, B; Su, J B; Corsin, A; Bouanani N el-H

    1991-11-01

    The coupling between myocardial beta-adrenergic receptors, adenylate cyclase activity, and the in vivo cardiac response to catecholamines is controversial in hyperthyroidism. The possibility of species differences in beta-adrenoceptor regulation after thyroxine treatment was studied in dogs and in rats. In dogs instrumented with a left ventricular (LV) pressure micromanometer, hyperthyroidism was induced by L-thyroxine (0.5 mg/kg/day i.v. for 10 days). After hyperthyroidism, heart rate was increased to 167 +/- 10 beats/min (control, 107 +/- 8 beats/min; p less than 0.005) with an increase of peak LV dP/dt from 4,243 +/- 471 to 6,105 +/- 862 mm Hg/sec (p less than 0.01). LV response to injection of increasing doses of isoproterenol and dobutamine was not significantly different before and after induction of the hyperthyroid state, as shown by the unchanged slopes of the LV peak dP/dt versus the log of the dose of isoproterenol and dobutamine. Bmax of beta-receptors measured in crude membranes using 3H-CGP 12177 and in homogenates using 125I-cyanopindolol was not increased in hyperthyroid animals as compared with a control group. Basal adenylate cyclase activity was not different in control and hyperthyroid dogs (32 +/- 3 versus 29 +/- 3 pmol/mg/min), and maximal adenylate cyclase activity response to isoproterenol was similar in control and hyperthyroid dogs. In contrast, in rats subjected to hyperthyroidism (0.5 mg/kg/day i.p. L-thyroxine for 10 days), Bmax of adrenoceptors measured using the same methods was significantly increased as compared with control (+72.5% using 3H-CGP 12177 and +41% using 125I-cyanopindolol, but adenylate cyclase activity was not increased in hyperthyroid rats. We conclude that both adenylate cyclase activity and LV response to catecholamines are not increased by thyroxine-induced hyperthyroidism in dogs and that, in contrast with rats, beta-adrenergic density is not increased in hyperthyroid dogs. This indicates a species difference in

  3. Alkaline phosphatase relieves desensitization of adenylate cyclase-coupled beta-adrenergic receptors in avian erythrocyte membranes

    SciTech Connect

    Stadel, J.M.; Rebar, R.; Crooke, S.T.

    1987-05-01

    Desensitization of adenylate cyclase-coupled ..beta..-adrenergic receptors in avian erythrocytes results in 40-65% decrease in agonist-stimulated adenylate cyclase activity and correlates with increased phosphorylation of ..beta..-adrenergic receptors. To assess the role of phosphorylation in desensitization, membranes from isoproterenol- and cAMP-desensitized turkey erythrocytes were incubated with alkaline phosphatase for 30 min at 37/sup 0/C, pH = 8.0. In both cases alkaline phosphatase treatment significantly reduced desensitization of agonist-stimulated adenylate cyclase activity by 40-60%. Similar results were obtained following alkaline phosphatase treatment of membranes from isoproterenol- and cAMP-desensitized duck erythrocytes. In addition, alkaline phosphatase treatment of membranes from duck erythrocytes desensitized with phorbol 12-mystrate 13-acetate returned adenylate cyclase activity to near control values. In all experiments inclusion of 20 mM NaPO/sub 4/ to inhibit alkaline phosphatase during treatment of membranes blocked the enzyme's effect on agonist-stimulated adenylate cyclase activity. These results demonstrate a role for phosphorylation in desensitization of adenylate cyclase-coupled ..beta..-adrenergic receptors in avian erythrocytes.

  4. β₂-adrenergic receptors protect axons during energetic stress but do not influence basal glio-axonal lactate shuttling in mouse white matter.

    PubMed

    Laureys, G; Valentino, M; Demol, F; Zammit, C; Muscat, R; Cambron, M; Kooijman, R; De Keyser, J

    2014-09-26

    In vitro studies have demonstrated that β2-adrenergic receptor activation stimulates glycogen degradation in astrocytes, generating lactate as a potential energy source for neurons. Using in vivo microdialysis in mouse cerebellar white matter we demonstrate continuous axonal lactate uptake and glial-axonal metabolic coupling of glutamate/lactate exchange. However, this physiological lactate production was not influenced by activation (clenbuterol) or blocking (ICI 118551) of β2-adrenergic receptors. In two-photon imaging experiments on ex vivo mouse corpus callosum subjected to aglycemia, β2-adrenergic activation rescued axons, whereas inhibition of axonal lactate uptake by α-cyano-4-hydroxycinnamic acid (4-CIN) was associated with severe axonal loss. Our results suggest that axonal protective effects of glial β2-adrenergic receptor activation are not mediated by enhanced lactate production. PMID:25064060

  5. Re-evaluating the efficacy of β-adrenergic agonists and antagonists in long QT-3 syndrome through computational modelling

    PubMed Central

    Ahrens-Nicklas, Rebecca C.; Clancy, Colleen E.; Christini, David J.

    2009-01-01

    Aims Long QT syndrome (LQTS) is a heterogeneous collection of inherited cardiac ion channelopathies characterized by a prolonged electrocardiogram QT interval and increased risk of sudden cardiac death. β-Adrenergic blockers are the mainstay of treatment for LQTS. While their efficacy has been demonstrated in LQTS patients harbouring potassium channel mutations, studies of β-blockers in subtype 3 (LQT3), which is caused by sodium channel mutations, have produced ambiguous results. In this modelling study, we explore the effects of β-adrenergic drugs on the LQT3 phenotype. Methods and results In order to investigate the effects of β-adrenergic activity and to identify sources of ambiguity in earlier studies, we developed a computational model incorporating the effects of β-agonists and β-blockers into an LQT3 mutant guinea pig ventricular myocyte model. β-Activation suppressed two arrhythmogenic phenomena, transmural dispersion of repolarization and early after depolarizations, in a dose-dependent manner. However, the ability of β-activation to prevent cardiac conduction block was pacing-rate-dependent. Low-dose β-blockade by propranolol reversed the beneficial effects of β-activation, while high dose (which has off-target sodium channel effects) decreased arrhythmia susceptibility. Conclusion These results demonstrate that β-activation may be protective in LQT3 and help to reconcile seemingly conflicting results from different experimental models. They also highlight the need for well-controlled clinical investigations re-evaluating the use of β-blockers in LQT3 patients. PMID:19264765

  6. Orexin receptor antagonists as therapeutic agents for insomnia

    PubMed Central

    Equihua, Ana C.; De La Herrán-Arita, Alberto K.; Drucker-Colin, Rene

    2013-01-01

    Insomnia is a common clinical condition characterized by difficulty initiating or maintaining sleep, or non-restorative sleep with impairment of daytime functioning. Currently, treatment for insomnia involves a combination of cognitive behavioral therapy (CBTi) and pharmacological therapy. Among pharmacological interventions, the most evidence exists for benzodiazepine (BZD) receptor agonist drugs (GABAA receptor), although concerns persist regarding their safety and their limited efficacy. The use of these hypnotic medications must be carefully monitored for adverse effects. Orexin (hypocretin) neuropeptides have been shown to regulate transitions between wakefulness and sleep by promoting cholinergic/monoaminergic neural pathways. This has led to the development of a new class of pharmacological agents that antagonize the physiological effects of orexin. The development of these agents may lead to novel therapies for insomnia without the side effect profile of hypnotics (e.g., impaired cognition, disturbed arousal, and motor balance difficulties). However, antagonizing a system that regulates the sleep-wake cycle may create an entirely different side effect profile. In this review, we discuss the role of orexin and its receptors on the sleep-wake cycle and that of orexin antagonists in the treatment of insomnia. PMID:24416019

  7. NMDA receptor antagonist ketamine impairs feature integration in visual perception.

    PubMed

    Meuwese, Julia D I; van Loon, Anouk M; Scholte, H Steven; Lirk, Philipp B; Vulink, Nienke C C; Hollmann, Markus W; Lamme, Victor A F

    2013-01-01

    Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans. PMID:24223927

  8. NMDA Receptor Antagonist Ketamine Impairs Feature Integration in Visual Perception

    PubMed Central

    Meuwese, Julia D. I.; van Loon, Anouk M.; Scholte, H. Steven; Lirk, Philipp B.; Vulink, Nienke C. C.; Hollmann, Markus W.; Lamme, Victor A. F.

    2013-01-01

    Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans. PMID:24223927

  9. Endogenous N-terminal Domain Cleavage Modulates α1D-Adrenergic Receptor Pharmacodynamics.

    PubMed

    Kountz, Timothy S; Lee, Kyung-Soon; Aggarwal-Howarth, Stacey; Curran, Elizabeth; Park, Ji-Min; Harris, Dorathy-Ann; Stewart, Aaron; Hendrickson, Joseph; Camp, Nathan D; Wolf-Yadlin, Alejandro; Wang, Edith H; Scott, John D; Hague, Chris

    2016-08-26

    The α1D-adrenergic receptor (ADRA1D) is a key regulator of cardiovascular, prostate, and central nervous system functions. This clinically relevant G protein-coupled receptor has proven difficult to study, as it must form an obligate modular homodimer containing the PDZ proteins scribble and syntrophin or become retained in the endoplasmic reticulum as non-functional protein. We previously determined that targeted removal of the N-terminal (NT) 79 amino acids facilitates ADRA1D plasma membrane expression and agonist-stimulated functional responses. However, whether such an event occurs in physiological contexts was unknown. Herein, we report the ADRA1D is subjected to innate NT processing in cultured human cells. SNAP near-infrared imaging and tandem-affinity purification revealed the ADRA1D is expressed as both full-length and NT truncated forms in multiple human cell lines. Serial truncation mapping identified the cleavage site as Leu(90)/Val(91) in the 95-amino acid ADRA1D NT domain, suggesting human cells express a Δ1-91 ADRA1D species. Tandem-affinity purification MS/MS and co-immunoprecipitation analysis indicate NT processing of ADRA1D is not required to form scribble-syntrophin macromolecular complexes. Yet, label-free dynamic mass redistribution signaling assays demonstrate that Δ1-91 ADRA1D agonist responses were greater than WT ADRA1D. Mutagenesis of the cleavage site nullified the processing event, resulting in ADRA1D agonist responses less than the WT receptor. Thus, we propose that processing of the ADRA1D NT domain is a physiological mechanism employed by cells to generate a functional ADRA1D isoform with optimal pharmacodynamic properties. PMID:27382054

  10. IL-1 receptor-antagonist (IL-1Ra) knockout mice show anxiety-like behavior by aging.

    PubMed

    Wakabayashi, Chisato; Numakawa, Tadahiro; Odaka, Haruki; Ooshima, Yoshiko; Kiyama, Yuji; Manabe, Toshiya; Kunugi, Hiroshi; Iwakura, Yoichiro

    2015-07-10

    Interleukin 1 (IL-1) plays a critical role in stress responses, and its mRNA is induced in the brain by restraint stress. Previously, we reported that IL-1 receptor antagonist (IL-1Ra) knockout (KO) mice, which lacked IL-1Ra molecules that antagonize the IL-1 receptor, showed anti-depression-like behavior via adrenergic modulation at the age of 8 weeks. Here, we report that IL-1Ra KO mice display an anxiety-like phenotype that is induced spontaneously by aging in the elevated plus-maze (EPM) test. This anxiety-like phenotype was improved by the administration of diazepam. The expression of the anxiety-related molecule glucocorticoid receptor (GR) was significantly reduced in 20-week-old but not in 11-week-old IL-1Ra KO mice compared to wild-type (WT) littermates. The expression of the mineralocorticoid receptor (MR) was not altered between IL-1Ra KO mice and WT littermates at either 11 or 20 weeks old. Analysis of monoamine concentration in the hippocampus revealed that tryptophan, the serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA), and the dopamine metabolite homovanillic acid (HVA) were significantly increased in 20-week-old IL-1Ra KO mice compared to littermate WT mice. These findings strongly suggest that the anxiety-like behavior observed in older mice was caused by the complicated alteration of monoamine metabolism and/or GR expression in the hippocampus. PMID:26002078

  11. Substituted tetrahydroisoquinolines as selective antagonists for the orexin 1 receptor.

    PubMed

    Perrey, David A; German, Nadezhda A; Gilmour, Brian P; Li, Jun-Xu; Harris, Danni L; Thomas, Brian F; Zhang, Yanan

    2013-09-12

    Increasing evidence implicates the orexin 1 (OX1) receptor in reward processes, suggesting OX1 antagonism could be therapeutic in drug addiction. In a program to develop an OX1 selective antagonist, we designed and synthesized a series of substituted tetrahydroisoquinolines and determined their potency in OX1 and OX2 calcium mobilization assays. Structure-activity relationship (SAR) studies revealed limited steric tolerance and a preference for electron deficiency at the 7-position. Pyridylmethyl groups were shown to be optimal for activity at the acetamide position. Computational studies resulted in a pharmacophore model and confirmed the SAR results. Compound 72 significantly attenuated the development of place preference for cocaine in rats. PMID:23941044

  12. [Treatment of pulmonary arterial hypertension: endothelin-receptor antagonists].

    PubMed

    Hoeper, M M

    2006-12-01

    Endothelin-1 (ET-1) is of significance in the pathophysiology and prognosis of pulmonary hypertension (PHT). Bosentan, an endothelin-receptor antagonist, currently plays a central role in the treatment of PHT, because it improves exercise capacity, hemodynamics, clinical symptoms and right ventricular function, achieving a survival duration of 2- 3 years. Bosentan causes an increase of transaminases in about 10% of patients, but this effect is reversible on dosage reduction or discontinuing the medication. However, transaminases should be measured every 4 weeks while patients are on bosentan. Almost all current guidelines list bosentan as of equal value to sildenafil or prostacyclin analogues in the first-line treatment of patients in NYHA functional class III and also, with narrower indications, of those in class IV. PMID:17139593

  13. Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise.

    PubMed

    Casey, Darren P; Madery, Brandon D; Pike, Tasha L; Eisenach, John H; Dietz, Niki M; Joyner, Michael J; Wilkins, Brad W

    2009-10-01

    We tested the hypothesis that adenosine contributes to augmented skeletal muscle vasodilation during hypoxic exercise. In separate protocols, subjects performed incremental rhythmic forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O2 saturation). In protocol 1 (n = 8), subjects received an intra-arterial administration of saline (control) and aminophylline (adenosine receptor antagonist). In protocol 2 (n = 10), subjects received intra-arterial phentolamine (alpha-adrenoceptor antagonist) and combined phentolamine and aminophylline administration. Forearm vascular conductance (FVC; in ml x min(-1).100 mmHg(-1)) was calculated from forearm blood flow (in ml/min) and blood pressure (in mmHg). In protocol 1, the change in FVC (DeltaFVC; change from normoxic baseline) during hypoxic exercise with saline was 172 +/- 29 and 314 +/- 34 ml x min(-1) x 100 mmHg(-1) (10% and 20%, respectively). Aminophylline administration did not affect DeltaFVC during hypoxic exercise at 10% (190 +/- 29 ml x min(-1)x100 mmHg(-1), P = 0.4) or 20% (287 +/- 48 ml x min(-1) x 100 mmHg(-1), P = 0.3). In protocol 2, DeltaFVC due to hypoxic exercise with phentolamine infusion was 313 +/- 30 and 453 +/- 41 ml x min(-1) x 100 mmHg(-1) (10% and 20% respectively). DeltaFVC was similar at 10% (352 +/- 39 ml min(-1) x 100 mmHg(-1), P = 0.8) and 20% (528 +/- 45 ml x min(-1) x 100 mmHg(-1), P = 0.2) hypoxic exercise with combined phentolamine and aminophylline. In contrast, DeltaFVC to exogenous adenosine was reduced by aminophylline administration in both protocols (P < 0.05 for both). These observations suggest that adenosine receptor activation is not obligatory for the augmented hyperemia during hypoxic exercise in humans. PMID:19661449

  14. Prostaglandins, H2-receptor antagonists and peptic ulcer disease.

    PubMed

    Bright-Asare, P; Habte, T; Yirgou, B; Benjamin, J

    1988-01-01

    Peptic ulcer develops when offensive factors overwhelm defensive processes in the gastroduodenal mucosa. Offensive factors include NSAIDs, hydrochloric acid-peptic activity, bile reflux, and some products of the lipoxygenase pathway such as leukotriene B4; whereas defensive processes are largely mediated by prostaglandins through poorly understood mechanisms uniformly termed cytoprotection. Cytoprotection, a physiological process working through the products of arachidonic acid metabolism, may result from the net effect of the protective actions of prostaglandins versus the damaging actions of leukotrienes. Some prostaglandins also have antisecretory effects. Therefore the peptic ulcer healing effects of prostaglandin analogues, all of which have significant antisecretory activity, may be more due to their antisecretory effects than primarily to their effects on mucosal defences. Certain drug-induced gastroduodenal lesions, e.g. NSAID-induced ulcers, which are often unresponsive to H2-receptor antagonists, have been healed and their recurrence prevented by the use of PGE1 and PGE2 analogues. All the prostaglandin analogues investigated to date in humans have the potential for inducing abortion, an important side effect which may limit their worldwide use. The optimal prostaglandin analogue for ulcer healing should not induce abortion and should be potently cytoprotective. The predominant damaging agent in the development of peptic ulcer disease is gastric hydrochloric acid. Thus, the worldwide established efficacy and safety of H2-receptor antagonists such as cimetidine, ranitidine, famotidine and most recently of roxatidine acetate suggest that these agents have become the standard by which other forms of anti-ulcer therapy should be judged. PMID:2905237

  15. Expression of histamine H4 receptor in human epidermal tissues and attenuation of experimental pruritus using H4 receptor antagonist.

    PubMed

    Yamaura, Katsunori; Oda, Manabu; Suwa, Eriko; Suzuki, Masahiko; Sato, Hiromi; Ueno, Koichi

    2009-10-01

    Many medicines exist which can cause pruritus (itching) as "serious adverse events." Many severe pruritic conditions respond poorly to histamine H1 receptor antagonists; there is no generally accepted antipruritic treatment. Recently described histamine H4 receptors are expressed in haematopoietic cells and have been linked to the pathology of allergy and asthma. We previously reported their expression in human dermal fibroblasts; in this study we have investigated H4 receptor expression in human epidermal tissue and found it to be greater in keratinocytes in the epidermal upper layer than in the lower layer. We have also investigated the effect of histamine H4 receptor antagonists on histamine H1 receptor antagonist-resistant pruritus using a mouse model. Scratching behavior was induced by histamine (300 nmol) or substance P (100 nmol) injected intradermally into the rostral part of the back of each mouse. Fexofenadine, a histamine H1 receptor antagonist, reduced scratching induced by histamine but not by substance P, whereas JNJ7777120, a histamine H4 receptor antagonist, significantly reduced both histamine- and substance P-induced scratching. These results suggest that H4 receptor antagonists may be useful for treatment of H1 receptor antagonist-resistant pruritus. PMID:19652466

  16. Activation of Human Brown Adipose Tissue by a β3-Adrenergic Receptor Agonist

    PubMed Central

    Cypess, Aaron M.; Weiner, Lauren S.; Roberts-Toler, Carla; Elía, Elisa Franquet; Kessler, Skyler H.; Kahn, Peter A.; English, Jeffrey; Chatman, Kelly; Trauger, Sunia A.; Doria, Alessandro; Kolodny, Gerald M.

    2015-01-01

    SUMMARY Increasing energy expenditure through activation of endogenous brown adipose tissue (BAT) is a potential approach to treat obesity and diabetes. The class of β3-adrenergic receptor (AR) agonists stimulates rodent BAT, but this activity has never been demonstrated in humans. Here we determined the ability of 200 mg oral mirabegron (Myrbetriq, Astellas Pharma, Inc.), a β3-AR agonist currently approved to treat overactive bladder, to stimulate BAT as compared to placebo. Mirabegron led to higher BAT metabolic activity as measured via 18F-fluorodeoxyglucose (18F-FDG) using positron emission tomography (PET) combined with computed tomography (CT) in all twelve healthy male subjects (p = 0.001), and it increased resting metabolic rate (RMR) by 203 ± 40 kcal/day (+13%; p = 0.001). BAT metabolic activity was also a significant predictor of the changes in RMR (p = 0.006). Therefore, a β3-AR agonist can stimulate human BAT thermogenesis and may be a promising treatment for metabolic disease. PMID:25565203

  17. The effects of spaceflight on adrenergic receptors and agonists and cell adhesion molecule expression

    NASA Technical Reports Server (NTRS)

    Mills, Paul J.; Perez, Christy J.; Adler, Karen A.; Ziegler, Michael G.; Meck, J. V. (Principal Investigator)

    2002-01-01

    Twenty-two astronauts who flew aboard 10 different US Space Shuttle flights were studied 10 days before launch, on landing day, and 2-4 days post-landing. After landing, plasma levels of norepinephrine (p<0.01) were elevated. Lymphocyte beta(2)-adrenergic receptors were desensitized 2-4 days post-landing (p<0.02). The density of CD62L on lymphocytes was unchanged but the densities of CD11a (p<0.01) and CD54 (p<0.001) were down-regulated. CD11a density was also down-regulated on monocytes (p<0.01). Neutrophils showed an up-regulation of CD11a (p<0.01) and a down-regulation of CD54 (p<0.01). CD11a density on neutrophils remained up-regulated (p<0.01) and CD54 density remained down-regulated (p<0.01) at 2-4 days post-landing. Circulating levels of soluble ICAM-1 (CD54) and soluble E-selectin (CD62E) were decreased after landing (p's<0.05). The data suggest that spaceflight leads to an environment that would support reduced leukocyte-endothelial adhesion. Sympathetic activation may contribute to this phenomenon.

  18. Uncoupling the Structure-Activity Relationships of β2 Adrenergic Receptor Ligands from Membrane Binding.

    PubMed

    Dickson, Callum J; Hornak, Viktor; Velez-Vega, Camilo; McKay, Daniel J J; Reilly, John; Sandham, David A; Shaw, Duncan; Fairhurst, Robin A; Charlton, Steven J; Sykes, David A; Pearlstein, Robert A; Duca, Jose S

    2016-06-23

    Ligand binding to membrane proteins may be significantly influenced by the interaction of ligands with the membrane. In particular, the microscopic ligand concentration within the membrane surface solvation layer may exceed that in bulk solvent, resulting in overestimation of the intrinsic protein-ligand binding contribution to the apparent/measured affinity. Using published binding data for a set of small molecules with the β2 adrenergic receptor, we demonstrate that deconvolution of membrane and protein binding contributions allows for improved structure-activity relationship analysis and structure-based drug design. Molecular dynamics simulations of ligand bound membrane protein complexes were used to validate binding poses, allowing analysis of key interactions and binding site solvation to develop structure-activity relationships of β2 ligand binding. The resulting relationships are consistent with intrinsic binding affinity (corrected for membrane interaction). The successful structure-based design of ligands targeting membrane proteins may require an assessment of membrane affinity to uncouple protein binding from membrane interactions. PMID:27239696

  19. [The association between beta-adrenergic receptor gene polymorphisms and personality traits].

    PubMed

    Numajiri, Maki; Aoki, Jun; Nishizawa, Daisuke; Kasai, Shinya; Ogai, Yasukazu; Ikeda, Kazutaka; Iwahashi, Kazuhiko

    2012-08-01

    The relationship between the polymorphisms (SNPs) of the beta-adrenergic receptor (beta-AR) gene and personality assessed by TCI (Temperament and Character Inventory), was studied among 192 healthy Japanese subjects (121 male subjects and 71 female subjects). In this study, the statistical analyses were performed overall and separately for each sex. As a result, it was shown that there were significant relationships between SD (self-directedness) and 49Ser/Gly (rs1801252) in ADRB1, P (persistence) and 389Arg/Gly (rs1801253) in ADRB1, and ST (self-transcendence) and 27Gln/Glu (rs1042714) in ADRB2 overall. Among the male subjects, there were further significant relationships between ST and 49Ser/Gly in ADRB1, NS (novelty-seeking), HA (harm avoidance) and P and 389Arg/Gly in ADRB1, and P and 64Arg/Trp(rsrs4994) in ADRB3. Among the female subjects, there were also significant relationships between SD and 49Ser/Gly in ADRB1, and C (cooperativeness) and 389Arg/Gly in ADRB1. Thus it was shown that there were correlations between beta-AR gene polymorphisms and several subscales of TCI. PMID:23012891

  20. β-Adrenergic receptor subtype signaling in heart: From bench to bedside

    PubMed Central

    Woo, Anthony Yiu Ho; Xiao, Rui-ping

    2012-01-01

    β-adrenergic receptor (βAR) stimulation by the sympathetic nervous system or circulating catecholamines is broadly involved in peripheral blood circulation, metabolic regulation, muscle contraction, and central neural activities. In the heart, acute βAR stimulation serves as the most powerful means to regulate cardiac output in response to a fight-or-flight situation, whereas chronic βAR stimulation plays an important role in physiological and pathological cardiac remodeling. There are three βAR subtypes, β1AR, β2AR and β3AR, in cardiac myocytes. Over the past two decades, we systematically investigated the molecular and cellular mechanisms underlying the different even opposite functional roles of β1AR and β2AR subtypes in regulating cardiac structure and function, with keen interest in the development of novel therapies based on our discoveries. We have made three major discoveries, including (1) dual coupling of β2AR to Gs and Gi proteins in cardiomyocytes, (2) cardioprotection by β2AR signaling in improving cardiac function and myocyte viability, and (3) PKA-independent, CaMKII-mediated β1AR apoptotic and maladaptive remodeling signaling in the heart. Based on these discoveries and salutary effects of β1AR blockade on patients with heart failure, we envision that activation of β2AR in combination with clinically used β1AR blockade should provide a safer and more effective therapy for the treatment of heart failure. PMID:22286918

  1. Propranolol responsiveness in vascular tumors is not determined by qualitative differences in adrenergic receptors.

    PubMed

    Boucek, Robert J; Kirsh, Andrew L; Majesky, Mark W; Perkins, Jonathan A

    2013-11-01

    Propranolol, a beta 1 (ADBR1) and beta 2 (ADBR2) adrenergic receptor blocker, accelerates regression of proliferating infantile hemangiomas (IH-P) while not affecting non-involuting congenital hemangiomas (NICH) and nonproliferating IH (IH-NP). To determine the expression of ADBRs in vascular tumors, immunofluorescent staining and confocal microscopy were employed to determine the in situ cellular distribution of ADBRs in formalin-fixed paraffin-embedded tissue sections of IH-P, IH-NP, and NICH. In situ cellular proliferation, indexed by Ki-67 expression, distinguished IH-P (n = 3) from both IH-NP (n = 3) and NICH (n = 2). In IH-P, IH-NP, and NICH tumor sections, both ADBR1 and ADBR2 were co-localized in both endothelial cells (ECs; GLUT1(+) in IH; CD31+ in NICH) and pericytes (smooth muscle actin). We tentatively conclude that either EC and/or pericytes in IH-P could be target(s) of propranolol. Cell proliferation, but not absence of either class of ADBR, distinguished the propranolol responsive IH-P from the nonresponsive IH-NP and NICH. PMID:24009211

  2. Immuno cross-reactivity suggests that catecholamine biosynthesis enzymes and beta adrenergic receptors may be related

    SciTech Connect

    Shorr, R.G.L.; Minnich, M.D.; Varrichio, A.; Strohsacker, M.W.; Gotlib, L.; Kruse, L.I.; DeWolf, W.E. Jr.; Crooke, S.T.

    1987-05-01

    Turkey red blood cell (RBC), Beta/sub 1/-adrenergic receptors (Bar) were prepared to electrophoretic homogeneity and denatured protein used to prepare rabbit anti-Bar antibodies. Anti-Bar activity was confirmed by immuno-adsorption of (/sup 125/I) cyanopindolol (CYP) labeled Bar. The catecholamine biosynthetic enzyme dopamine beta hydroxylase (DBH) was purified from bovine adrenal medullae chromaffin vesicles by ion exchange, size exclusion and concanavalin-A-Sepharose chromatography. Final DBH specific activities were 42 +/- 4 U/mg protein. Homogeneity was confirmed by non-denaturing PAGE. Bar was compared to DBH by anti-Bar antibody cross-reactivity. DBH and Bar were recognized by anti-Bar antibodies on immunoblotting. No interactions were observed with preimmune controls. Similar results were obtained with glycosylated and deglycosylated DBH suggesting that the antibodies recognize DBH amino acid sequence and not associated carbohydrate. Cross-reactive antibodies were purified by affinity chromatography using immobilized DBH and shown to immuno-adsorb (/sup 125/I)CYP labeled Bar. These results suggest that the catecholamine biosynthetic enzyme DBH and Bar may be related in structure.

  3. Norepinephrine-Induced Adrenergic Activation Strikingly Increased the Atrial Fibrillation Duration through β1- and α1-Adrenergic Receptor-Mediated Signaling in Mice

    PubMed Central

    Hasegawa, Nozomi; Cai, Wenqian; Jin, Huiling; Hidaka, Yuko; Prajapati, Rajesh; Umemura, Masanari; Yokoyama, Utako; Sato, Motohiko; Okumura, Satoshi; Ishikawa, Yoshihiro

    2015-01-01

    Background Atrial fibrillation (AF) is the most common arrhythmias among old people. It causes serious long-term health problems affecting the quality of life. It has been suggested that the autonomic nervous system is involved in the onset and maintenance of AF in human. However, investigation of its pathogenesis and potential treatment has been hampered by the lack of suitable AF models in experimental animals. Objectives Our aim was to establish a long-lasting AF model in mice. We also investigated the role of adrenergic receptor (AR) subtypes, which may be involved in the onset and duration of AF. Methods and Results Trans-esophageal atrial burst pacing in mice could induce AF, as previously shown, but with only a short duration (29.0±8.1 sec). We found that adrenergic activation by intraperitoneal norepinephrine (NE) injection strikingly increased the AF duration. It increased the duration to more than 10 minutes, i.e., by more than 20-fold (656.2±104.8 sec; P<0.001). In this model, a prior injection of a specific β1-AR blocker metoprolol and an α1-AR blocker prazosin both significantly attenuated NE-induced elongation of AF. To further explore the mechanisms underlying these receptors’ effects on AF, we assessed the SR Ca2+ leak, a major trigger of AF, and consequent spontaneous SR Ca2+ release (SCR) in atrial myocytes. Consistent with the results of our in-vivo experiments, both metoprolol and prazosin significantly inhibited the NE-induced SR Ca2+ leak and SCR. These findings suggest that both β1-AR and α1-AR may play important roles in the development of AF. Conclusions We have established a long-lasting AF model in mice induced by adrenergic activation, which will be valuable in future AF study using experimental animals, such as transgenic mice. We also revealed the important role of β1- and α1-AR-mediated signaling in the development of AF through in-vivo and in-vitro experiments. PMID:26203906

  4. Assessment of anti-arrhythmic activity of antipsychotic drugs in an animal model: influence of non-cardiac α₁-adrenergic receptors.

    PubMed

    Mow, Tomas; Frederiksen, Kristen; Thomsen, Morten B

    2015-02-01

    Torsades de Pointes (TdP) is a potentially lethal cardiac arrhythmia and a known adverse effect of many drugs secondary to block of the rapidly activating delayed rectifier potassium current (IKr). In animal models antipsychotic drugs have shown reduced pro-arrhythmic potential compared to drugs with comparable IKr-blocking characteristics. The reduced pro-arrhythmic properties of antipsychotic drugs has been attributed to a variety of different causes e.g., effects on α₁-adrenergic receptors, β-adrenergic receptors, muscarinic receptors or cardiac ion channels like Ca(2+)- and Na(+)-channels. Since only limited experimental information exists about the effects of α₁-adrenergic receptor activity of antipsychotic drugs in pro-arrhythmic models, we have decided to investigate this. In this study we show that four antipsychotic drugs all have high affinity for α₁-adrenergic receptor (sertindole>risperidone>haloperidol>olanzapine) and all block IKr (sertindole>haloperidol>risperidone>olanzapine). In canine Purkinje fibres, α₁-adrenergic stimulation prolonged action potential duration; however, the stimulation does not cause afterdepolarizations, even in the presence of dofetilide-induced delayed repolarization. We showed for the first time in an in vivo pro-arrhythmic rabbit model that several antipsychotic drugs in accordance with their known α₁-adrenergic receptor blocking properties reduced the incidence of drug-induced TdP and that the overall ability of the antipsychotic drugs to prevent TdP was associated with prevention of methoxamine induced increase in blood pressure. Further investigations are required to clarify the relative importance of α₁-adrenergic receptor antagonism in conjunction with the additional effects of antipsychotic drugs on various receptors and ion channels. PMID:25530269

  5. Beta-3 adrenergic receptors could be significant factors for overactive bladder-related symptoms

    PubMed Central

    Yamamichi, Fukashi; Shigemura, Katsumi; Behnsawy, Hosny M; Yamashita, Masuo; Shirakawa, Toshiro; Fujisawa, Masato

    2015-01-01

    The treatment failure often happens in overactive bladder (OAB) partly owing to its unknown pathogenesis. The purpose of this study is to find significant receptors or biological markers for OAB-related symptoms for establishment of potential order-made therapeutic strategies. The overactive bladder symptom scores (OABSS) and international prostate symptom scores (IPSS)/quality of life (QOL) were questioned in all the 18 patients with OAB diagnosis. Their bladder mucosal tissues were taken from the random biopsy of bladder cancer suspected patients without any finding such as inflammation or carcinoma in situ. They were investigated quantitatively by immunohistochemical (IHC) stainings for inflammatory or immune-system (Interleukin (IL)-6 and cyclooxygenase-2 (Cox-2)), Caspase-3 apoptosis markers, angiogenesis (CD-31), epithelial-mesenchymal transition (E-cadherin) and muscarinic receptor (Muscarine-2 (M)-2), adrenergic receptors (ARs) (alpha 1-d (α1-d) and beta-3 (β-3)). The statistical correlation between the expressions of these 5 markers and 3 receptors and these symptom scores were examined under the comparison between OAB patients and control patients who had urgency score with less than 2 in OABSS. The OABSS and IPSS/QOL was 7.39 ± 2.69 and 21.2 ± 6.59/4.33 ± 1.33, respectively but those of control patients were 2.00 ± 1.41 and 10.1 ± 9.52/2.14 ± 1.46, respectively (P<0.05). Regarding the correlation of those markers’ expressions and symptom scores, in OAB patients, OABSS total significantly correlated with β-3 AR expressions (P=0.0457). IPSS post-voiding significantly correlated with β-3 AR expressions (P=0.0308) but no significant relationship in control patients (P>0.05). In conclusion, this study demonstrated that β-3 AR in our tested 8 markers or receptors was correlated strongly with OAB-related symptoms. These data may help elucidate the pathophysiology of OAB and offer possible strategy for its order-made therapies. PMID:26617941

  6. Metabotropic glutamate receptor antagonists but not NMDA antagonists affect conditioned taste aversion acquisition in the parabrachial nucleus of rats.

    PubMed

    Vales, Karel; Zach, Petr; Bielavska, Edita

    2006-02-01

    The effect of glutamate receptor antagonists on conditioned taste aversion (CTA) was studied in rats. The association of the short-term memory of a gustatory conditioned stimulus (CS) with visceral malaise (unconditioned stimulus, US) in the CTA paradigm takes place in the parabrachial nuclei (PBN) of the brainstem. The first direct evidence of participation of glutamatergic neurotransmission in the PBN during CTA demonstrated that the extracellular level of glutamate rises during saccharin drinking (Bielavska et al. in Brain Res 887:413-417, 2000). Our results show an effect of microdialysis administration of selective GluR antagonists into the PBN on the formation of CTA engram. We used four glutamate receptor (GluR) antagonists of different types (D-AP5, MK-801 as antagonists of ionotropic GluR and L-AP3, MSPG as antagonists of metabotropic GluR). The disruptive effect of MK-801 on CTA formation in the PBN is concentration-dependent, with the greatest inhibition under the higher concentrations eliciting significant disruption. The application of D-AP5 (0.1, 1, 5 mM) did not elicit a statistically significant blockade of CTA acquisition. This indicates that the association of the US-CS in the PBN is not dependent on NMDA receptors. On the contrary, application of L-AP3 (0.1, 1, 5 mM) blocked the CS-US association. PMID:16273405

  7. Adenosine receptor agonists attenuate and adenosine receptor antagonists exacerbate opiate withdrawal signs.

    PubMed

    Kaplan, G B; Sears, M T

    1996-01-01

    Previous studies have demonstrated a role for adenosine in mediating opiate effects. Adenosine receptors and their functions have been shown to be regulated by chronic opiate treatment. This study examines the role of adenosine receptors in the expression of opiate withdrawal behaviors. The effects of single doses of parenterally administered adenosine receptor subtype-selective agonists and antagonists on opiate withdrawal signs in morphine-dependent mice were measured. Mice received subcutaneous morphine pellet treatment for 72 h and then underwent naloxone-precipitated withdrawal after pretreatment with adenosinergic agents. Adenosine agonists attenuated different opiate withdrawal signs. The A1 agonist R-N6(phenylisopropyl)adenosine (0, 0.01, 0.02 mg/kg, IP) significantly reduced wet dog shakes and withdrawal diarrhea, while the A2a-selective agonist 2-p-(2-carboxethyl)phenylethylamino-5'-N-ethylcarboxamido adenosine or CGS 21680 (0, 0.01, 0.05 mg/kg, IP) significantly inhibited teeth chattering and forepaw treads. Adenosine receptor antagonists enhanced different opiate withdrawal signs. The adenosine A1 antagonist 1,3-dipropyl-8-cyclopentylxanthine (0, 1, 10 mg/kg, IP) significantly increased weight loss and the A2 antagonist, 3,7-dimethyl-1-propargylxanthine (0, 1 and 10 mg/kg, IP) enhanced wet dog shakes and withdrawal diarrhea. Treatment effects of adenosinergic agents were not due to nonspecific motor effects, as demonstrated by activity monitoring studies. These results support a role for adenosine receptors in the expression of opiate withdrawal and suggest the potential utility of adenosine agonists in its treatment. PMID:8741956

  8. Dihydromorphine-peptide hybrids with delta receptor agonistic and mu receptor antagonistic actions

    SciTech Connect

    Smith, C.B.; Medzihradsky, F.; Woods, J.H.

    1986-03-05

    The actions of two morphine derivatives with short peptide side chains were evaluated upon the contraction of the isolated mouse vas deferens and upon displacement of /sup 3/H-etorphine from rat brain membranes. NIH-9833 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-phenylalanyl-L-leucine ethyl ester HCl) was a potent agonist upon the vas deferens. Its EC50 for inhibition of the twitch was 1.2 +/- 0.1 nM. Both naltrexone (10/sup -7/ M) a relatively nonselective opioid antagonist, and ICI-174864 (10/sup -/' M) a highly selective delta receptor antagonist, blocked the actions of NIH-9833 which indicates that this drug is a delta receptor agonist. In contrast, NIH-9835 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-glycyl-L-phenylalanyl-L-leucine ethyl ester HCl), which differs from NIH-9835 by the presence of a single amino acid residue, was devoid of opioid agonistic activity but was a potent antagonist of the inhibitory actions on the vas deferens of morphine and sufentanil. NIH-9833 and NIH-9835 were potent displacers of /sup 3/H-etorphine from rat cerebral membranes with EC50's of 0.58 nM and 1.7 nM, respectively. The observation that addition of a single glycyl group changes a dihydromorphine-peptide analog from a potent delta receptor agonist to an equally potent mu receptor antagonist suggests that the two receptor sites might be structurally quite similar.

  9. Localization of beta-adrenergic receptors in transmural slices of myocardium with quantitative autoradiography

    SciTech Connect

    Murphree, S.S.; Saffitz, J.E.

    1986-03-01

    Alterations in the density of myocardial ..beta..-adrenergic receptors (..beta..AR) induced by ischemia may be important in the pathophysiology of acute ischemic heart disease. Conventional binding assays in tissue homogenates lack the anatomic resolution required for cell-specific analysis of early alterations in receptor density induced by ischemia. Accordingly, the authors have developed methods for localization of ..beta..AR in transmural slices of feline left ventricle with quantitative autoradiography. Frozen sections were incubated with /sup 125/I-iodocyanopindolol (ICYP) +/- Z-propranolol for 60 min at 37/sup 0/. Non-specifically bound radioactivity was removed by rinsing the sections for 60 min at 22/sup 0/. At saturating concentrations of ICYP, > 90% specific binding was achieved. Specific binding was rapid, saturable, of high affinity and proportional to section thickness (B/sub max/ = 26.5 +/- 6.4 fmol/mg tissue protein; K/sub d/ = 10.0 +/- 2.1 pM; N = 14). Agonist binding showed the rank order of potency expected for ..beta..AR (IC/sub 50/ = 0.12 ..mu..M, isoproterenol; .18 ..mu..M, norepinephrine; .54 ..mu..M, epinephrine) and demonstrated stereo-selectivity (IC/sub 50/ = .013 ..mu..M, Z-isoproterenol; 9.5 ..mu..M, d-isoproterenol). Quantitative autoradiography with both film and emulsion methods will permit regional analysis of ..beta..AR density in large transmural sections as well as cell-specific analysis at the microscopic level.

  10. Caveolin-3 regulates compartmentation of cardiomyocyte beta2-adrenergic receptor-mediated cAMP signaling.

    PubMed

    Wright, Peter T; Nikolaev, Viacheslav O; O'Hara, Thomas; Diakonov, Ivan; Bhargava, Anamika; Tokar, Sergiy; Schobesberger, Sophie; Shevchuk, Andrew I; Sikkel, Markus B; Wilkinson, Ross; Trayanova, Natalia A; Lyon, Alexander R; Harding, Sian E; Gorelik, Julia

    2014-02-01

    The purpose of this study was to investigate whether caveolin-3 (Cav3) regulates localization of β2-adrenergic receptor (β2AR) and its cAMP signaling in healthy or failing cardiomyocytes. We co-expressed wildtype Cav3 or its dominant-negative mutant (Cav3DN) together with the Förster resonance energy transfer (FRET)-based cAMP sensor Epac2-camps in adult rat ventricular myocytes (ARVMs). FRET and scanning ion conductance microscopy were used to locally stimulate β2AR and to measure cytosolic cAMP. Cav3 overexpression increased the number of caveolae and decreased the magnitude of β2AR-cAMP signal. Conversely, Cav3DN expression resulted in an increased β2AR-cAMP response without altering the whole-cell L-type calcium current. Following local stimulation of Cav3DN-expressing ARVMs, β2AR response could only be generated in T-tubules. However, the normally compartmentalized β2AR-cAMP signal became diffuse, similar to the situation observed in heart failure. Finally, overexpression of Cav3 in failing myocytes led to partial β2AR redistribution back into the T-tubules. In conclusion, Cav3 plays a crucial role for the localization of β2AR and compartmentation of β2AR-cAMP signaling to the T-tubules of healthy ARVMs, and overexpression of Cav3 in failing myocytes can partially restore the disrupted localization of these receptors. PMID:24345421

  11. Caveolin-3 regulates compartmentation of cardiomyocyte beta2-adrenergic receptor-mediated cAMP signaling

    PubMed Central

    Wright, Peter T.; Nikolaev, Viacheslav O.; O’Hara, Thomas; Diakonov, Ivan; Bhargava, Anamika; Tokar, Sergiy; Schobesberger, Sophie; Shevchuk, Andrew I.; Sikkel, Markus B.; Wilkinson, Ross; Trayanova, Natalia A.; Lyon, Alexander R.; Harding, Sian E.; Gorelik, Julia

    2014-01-01

    The purpose of this study was to investigate whether caveolin-3 (Cav3) regulates localization of β2-adrenergic receptor (β2AR) and its cAMP signaling in healthy or failing cardiomyocytes. We co-expressed wildtype Cav3 or its dominant-negative mutant (Cav3DN) together with the Förster resonance energy transfer (FRET)-based cAMP sensor Epac2-camps in adult rat ventricular myocytes (ARVMs). FRET and scanning ion conductance microscopy were used to locally stimulate β2AR and to measure cytosolic cAMP. Cav3 overexpression increased the number of caveolae and decreased the magnitude of β2AR-cAMP signal. Conversely, Cav3DN expression resulted in an increased β2AR-cAMP response without altering the whole-cell L-type calcium current. Following local stimulation of Cav3DN-expressing ARVMs, β2AR response could only be generated in T-tubules. However, the normally compartmentalized β2AR-cAMP signal became diffuse, similar to the situation observed in heart failure. Finally, overexpression of Cav3 in failing myocytes led to partial β2AR redistribution back into the T-tubules. In conclusion, Cav3 plays a crucial role for the localization of β2AR and compartmentation of β2AR-cAMP signaling to the T-tubules of healthy ARVMs, and overexpression of Cav3 in failing myocytes can partially restore the disrupted localization of these receptors. PMID:24345421

  12. Vasopressin receptor antagonists and their role in clinical medicine

    PubMed Central

    Narayen, Girish; Mandal, Surya Narayan

    2012-01-01

    Hyponatremia is the most common electrolyte abnormality in hospitalized patients. Its treatment is based not only on extracellular fluid volume status of patients but also on its pathogenetic mechanisms. Conventional treatment of hyponatremia like fluid restriction, which is useful in euvolemic and hypervolemic hyponatremia, has very poor patient compliance over long term. Vasopressin receptor antagonists (Vaptans) are a new group of nonpeptide drugs which have been used in various clinical conditions with limited success. Whereas conivaptan is to be administered intravenously, the other vaptans like tolvaptan, lixivaptan, and satavaptan are effective as oral medication. They produce aquaresis by their action on vasopressin type 2 (V2R) receptors in the collecting duct and thus increase solute free water excretion. Vaptans are being used as an alternative to fluid restriction in euvolemic and hypervolemic hyponatremic patients. Efficacy of vaptans is now well accepted for management of correction of hyponatremia over a short period. However, its efficacy in improving the long-term morbidity and mortality in patients with chronic hyponatremia due to cirrhosis and heart failure is yet to be established. Vaptans have not become the mainstay treatment of hyponatremia yet. PMID:22470853

  13. CGRP Receptor Antagonists in the Treatment of Migraine

    PubMed Central

    Durham, Paul L.; Vause, Carrie V.

    2011-01-01

    Based on preclinical and clinical studies, the neuropeptide calcitonin gene-related peptide (CGRP) is proposed to play a central role in the underlying pathology of migraine. CGRP and its receptor are widely expressed in both the peripheral and central nervous system by multiple cell types involved in the regulation of inflammatory and nociceptive responses. Peripheral release of CGRP from trigeminal nerve fibers within the dura and from the cell body of trigeminal ganglion neurons is likely to contribute to peripheral sensitization of trigeminal nociceptors. Similarly, the release of CGRP within the trigeminal nucleus caudalis can facilitate activation of nociceptive second order neurons and glial cells. Thus, CGRP is involved in the development and maintenance of persistent pain, central sensitization, and allodynia, events characteristic of migraine pathology. In contrast, CGRP release within the brain is likely to function in an anti-nociceptive capacity. This review will focus on the development and clinical data on CGRP receptor antagonists as well as discussing their potential roles in migraine therapy via modulation of multiple cell types within the peripheral and central nervous systems. PMID:20433208

  14. Quantitative autoradiographic analysis of /sup 125/I-pindolol binding in Fischer 344 rat brain: changes in beta-adrenergic receptor density with aging

    SciTech Connect

    Miller, J.A.; Zahniser, N.R.

    1988-05-01

    Age-related changes in beta-adrenergic receptor density in Fischer 344 rat brain were examined using in vitro /sup 125/I-pindolol (IPIN) binding and quantitative autoradiographic analysis. Localized protein concentrations were determined using a new quantitative histological technique, and these were used to normalize the densities of receptors. Saturation binding studies in brain sections revealed 40-50% decreases in beta-adrenergic receptor density in the thalamus of 23-25-month-old and the cerebellum and brainstem of both 18-19-month-old and 23-25-month-old compared to 4-6-month-old rats. The loss of cerebellar beta-adrenergic receptors may be correlated with reports of deficits in sensitivity to beta-adrenergic-mediated transmission in the cerebellum of aged rats. No changes in specific IPIN binding with age were observed in rat cortex or hippocampus. In all areas examined no age-related differences were observed in receptor affinity. No changes in protein concentration were found in any of the areas examined in the different aged animals. These results demonstrate a region-specific loss of beta-adrenergic receptors with age in the brain of Fischer 344 rats.

  15. Cardiac β2-Adrenergic Receptor Phosphorylation at Ser355/356 Regulates Receptor Internalization and Functional Resensitization.

    PubMed

    Fan, Xiaofang; Gu, Xuejiang; Zhao, Ru; Zheng, Qingqing; Li, Lan; Yang, Wenbing; Ding, Lu; Xue, Feng; Fan, Junming; Gong, Yongsheng; Wang, Yongyu

    2016-01-01

    Previous studies have demonstrated that β2-adrenergic receptors (β2ARs) can be phosphorylated by G protein-coupled receptor kinases (GRKs) and protein kinase A (PKA), affecting β2AR internalization and desensitization. However, the exact physiological function of β2ARs in cardiomyocytes is unknown. In this study, we showed that neonatal mouse cardiomyocytes had different contraction and internalization responses to sustained or repeated, transient agonist stimulation. Specifically, short-time stimulation (10 min) with epinephrine or norepinephrine increased the cardiomyocyte contraction rate, reaching a maximum at 5 min, followed by a slow decline. When the agonist was re-added after a 60-min wash-out period, the increase in the cardiomyocyte contraction rate was similar to the initial response. In contrast, when cardiomyocytes were exposed continuously to epinephrine or norepinephrine for 60 min, the second agonist stimulation did not increase the contraction response. These results indicated that continuous β2AR stimulation caused functional desensitization. Phosphorylation of β2ARs at serine (Ser)355/356 GRK phosphorylation sites, but not at Ser345/346 PKA phosphorylation sites increased with continuous epinephrine stimulation for 60 min. Accordingly, β2AR internalization increased. Interestingly, β2AR internalization was blocked by mutations at the GRK phosphorylation sites, but not by mutations at the PKA phosphorylation sites. Furthermore, inhibition of β2AR dephosphorylation by okadaic acid, a phosphatase 2A inhibitor, impaired the recovery of internalized β2ARs and reduced the cardiomyocyte contraction rate in response to epinephrine. Finally, epinephrine treatment induced the physical interaction of β-arrestin with internalized β2ARs in cardiomyocytes. Together, these data revealed the essential role of the Ser355/356 phosphorylation status of β2ARs in regulating receptor internalization and physiological resensitization in neonatal

  16. Cardiac β2-Adrenergic Receptor Phosphorylation at Ser355/356 Regulates Receptor Internalization and Functional Resensitization

    PubMed Central

    Zhao, Ru; Zheng, Qingqing; Li, Lan; Yang, Wenbing; Ding, Lu; Xue, Feng; Fan, Junming; Gong, Yongsheng

    2016-01-01

    Previous studies have demonstrated that β2-adrenergic receptors (β2ARs) can be phosphorylated by G protein-coupled receptor kinases (GRKs) and protein kinase A (PKA), affecting β2AR internalization and desensitization. However, the exact physiological function of β2ARs in cardiomyocytes is unknown. In this study, we showed that neonatal mouse cardiomyocytes had different contraction and internalization responses to sustained or repeated, transient agonist stimulation. Specifically, short-time stimulation (10 min) with epinephrine or norepinephrine increased the cardiomyocyte contraction rate, reaching a maximum at 5 min, followed by a slow decline. When the agonist was re-added after a 60-min wash-out period, the increase in the cardiomyocyte contraction rate was similar to the initial response. In contrast, when cardiomyocytes were exposed continuously to epinephrine or norepinephrine for 60 min, the second agonist stimulation did not increase the contraction response. These results indicated that continuous β2AR stimulation caused functional desensitization. Phosphorylation of β2ARs at serine (Ser)355/356 GRK phosphorylation sites, but not at Ser345/346 PKA phosphorylation sites increased with continuous epinephrine stimulation for 60 min. Accordingly, β2AR internalization increased. Interestingly, β2AR internalization was blocked by mutations at the GRK phosphorylation sites, but not by mutations at the PKA phosphorylation sites. Furthermore, inhibition of β2AR dephosphorylation by okadaic acid, a phosphatase 2A inhibitor, impaired the recovery of internalized β2ARs and reduced the cardiomyocyte contraction rate in response to epinephrine. Finally, epinephrine treatment induced the physical interaction of β-arrestin with internalized β2ARs in cardiomyocytes. Together, these data revealed the essential role of the Ser355/356 phosphorylation status of β2ARs in regulating receptor internalization and physiological resensitization in neonatal

  17. Angiotensin II receptor blockade in normotensive subjects: A direct comparison of three AT1 receptor antagonists.

    PubMed

    Mazzolai, L; Maillard, M; Rossat, J; Nussberger, J; Brunner, H R; Burnier, M

    1999-03-01

    Use of angiotensin (Ang) II AT1 receptor antagonists for treatment of hypertension is rapidly increasing, yet direct comparisons of the relative efficacy of antagonists to block the renin-angiotensin system in humans are lacking. In this study, the Ang II receptor blockade induced by the recommended starting dose of 3 antagonists was evaluated in normotensive subjects in a double-blind, placebo-controlled, randomized, 4-way crossover study. At 1-week intervals, 12 subjects received a single dose of losartan (50 mg), valsartan (80 mg), irbesartan (150 mg), or placebo. Blockade of the renin-angiotensin system was assessed before and 4, 24, and 30 hours after drug intake by 3 independent methods: inhibition of the blood pressure response to exogenous Ang II, in vitro Ang II receptor assay, and reactive changes in plasma Ang II levels. At 4 hours, losartan blocked 43% of the Ang II-induced systolic blood pressure increase; valsartan, 51%; and irbesartan, 88% (P<0.01 between drugs). The effect of each drug declined with time. At 24 hours, a residual effect was found with all 3 drugs, but at 30 hours, only irbesartan induced a marked, significant blockade versus placebo. Similar results were obtained when Ang II receptor blockade was assessed with an in vitro receptor assay and by the reactive rise in plasma Ang II levels. This study thus demonstrates that the first administration of the recommended starting dose of irbesartan induces a greater and longer lasting Ang II receptor blockade than that of valsartan and losartan in normotensive subjects. PMID:10082498

  18. 4,4'-Di-isothiocyanatostilbene-2,2'-disulphonic acid ('DIDS') activates protein kinase C and Na+/H+ exchange in human platelets via alpha 2A-adrenergic receptors.

    PubMed Central

    Nieuwland, R; Van Willigen, G; Akkerman, J W

    1993-01-01

    Most agonists stimulate platelets by inducing Ca2+ mobilization, Ca2+ influx and protein kinase C (PKC) activation leading to Na+/H+ exchange, exposure of fibrinogen-binding sites and aggregation. In contrast, previous studies showed that adrenaline induces exposure of fibrinogen-binding sites and aggregation without appreciable changes in cystolic Ca2+ content or PKC activity. In the present study we investigated platelet responses mediated via alpha 2A-adrenergic receptors, using 4,4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS), which is known to bind to this type of receptor. Addition of DIDS (2-20 microM) induced (i) a rise in cytosolic pH of 0.23 +/- 0.05 pH unit (n = 5) as detected by BCECF fluorescence, due to activation of the Na+/H+ exchanger, (ii) a 3.5-4-fold increase in the phosphorylation of the 47 kDa protein, a major substrate of PKC, (iii) exposure of 81,072 +/- 7293 (n = 3) binding sites for 125I-fibrinogen per platelet, and (iv) irreversible aggregation. These responses occurred without changes in cytosolic [Ca2+], secretion of dense-granule contents and enhanced phosphoinositide metabolism, and were not affected by inhibition of thromboxane A2 generation (30 microM indomethacin). The alpha 2A-adrenergic-receptor antagonists oxymetazoline (500 microM) and yohimbine (1 mM) completely abolished DIDS-induced responses. Inhibition of PKC (1 microM staurosporine) prevented phosphorylation of the 47 kDa protein, the increase in Na+/H+ exchange and exposure of fibrinogen-binding sites. Thus our present data suggest that activation of PKC is an early event in DIDS-induced platelet activation via the alpha 2A-adrenergic receptor, which precedes any of the other known signal-transducing sequences. PMID:8393664

  19. Adenosine A1 receptors heterodimerize with β1- and β2-adrenergic receptors creating novel receptor complexes with altered G protein coupling and signaling.

    PubMed

    Chandrasekera, P Charukeshi; Wan, Tina C; Gizewski, Elizabeth T; Auchampach, John A; Lasley, Robert D

    2013-04-01

    G protein coupled receptors play crucial roles in mediating cellular responses to external stimuli, and increasing evidence suggests that they function as multiple units comprising homo/heterodimers and hetero-oligomers. Adenosine and β-adrenergic receptors are co-expressed in numerous tissues and mediate important cellular responses to the autocoid adenosine and sympathetic stimulation, respectively. The present study was undertaken to examine whether adenosine A1ARs heterodimerize with β1- and/or β2-adrenergic receptors (β1R and β2R), and whether such interactions lead to functional consequences. Co-immunoprecipitation and co-localization studies with differentially epitope-tagged A1, β1, and β2 receptors transiently co-expressed in HEK-293 cells indicate that A1AR forms constitutive heterodimers with both β1R and β2R. This heterodimerization significantly influenced orthosteric ligand binding affinity of both β1R and β2R without altering ligand binding properties of A1AR. Receptor-mediated ERK1/2 phosphorylation significantly increased in cells expressing A1AR/β1R and A1AR/β2R heteromers. β-Receptor-mediated cAMP production was not altered in A1AR/β1R expressing cells, but was significantly reduced in the A1AR/β2R cells. The inhibitory effect of the A1AR on cAMP production was abrogated in both A1AR/β1R and A1AR/β2R expressing cells in response to the A1AR agonist CCPA. Co-immunoprecipitation studies conducted with human heart tissue lysates indicate that endogenous A1AR, β1R, and β2R also form heterodimers. Taken together, our data suggest that heterodimerization between A1 and β receptors leads to altered receptor pharmacology, functional coupling, and intracellular signaling pathways. Unique and differential receptor cross-talk between these two important receptor families may offer the opportunity to fine-tune crucial signaling responses and development of more specific therapeutic interventions. PMID:23291003

  20. The acute modulation of norepinephrine on immune responses and genes expressions via adrenergic receptors in the giant freshwater prawn, Macrobrachium rosenbergii.

    PubMed

    Chang, Chin-Chyuan; Tsai, Wan-Lin; Jiang, Jia-Rong; Cheng, Winton

    2015-10-01

    Norepinephrine (NE), immunocompetent parameters (total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, phagocytic activity and clearance efficiency to Lactococcus garvieae), and prophenoloxidase (proPO) system-related genes (lipopolysaccharide- and β-1,3-glucan-binding protein, LGBP; prophenoloxidase, proPO; peroxinectin, PE; α2-macroglobulin, α2-M) expressions were investigated in Macrobrachium rosenbergii received NE through injection at 50 pmol/prawn after 0, 30, 60, and 120 min. Furthermore, the PO activity, RB, SOD activity, phagocytic activity and proPO system-related genes expressions were determined in haemocytes incubated with cacodylate buffer (CAC), NE, and NE co-treated with various adrenergic receptor (AR) antagonists in vitro. Results showed that NE, THC, granular cells, PO activity, SOD activity, proPO system-related genes expressions, and phagocytic activity and clearance efficiency to L. garvieae increased; PO activity per granulocyte and RB per haemocyte decreased from 30 to 120 min; semigranular cells and RB increased in the initial 30 min, and then decreased at 120 min when the prawns received NE by injection. In vitro studies, all the determined immune parameters and genes expressions were significantly decreased in haemocytes incubated with NE after 30 min. The negative effects of NE were prevented on the PO activity and phagocytic activity by the β-AR antagonist of metoprolol (Met), on the SOD activity by the β-AR antagonist of propranolol (Pro), on the RB by the β-AR antagonist of Met and prazosin (Pra), and on the proPO system-related genes expressions by α-AR antagonist of Pra. These results show that NE modulates prawn haemocytes proPO system-related genes expressions via α1-AR, PO activity and phagocytosis via β1-AR, respiratory burst via α1-and β1-ARs, and SOD activity via β2-AR. It is concluded that NE stimulates the regulation of immunocompetence parameters

  1. Biomolecular recognition of antagonists by α7 nicotinic acetylcholine receptor: Antagonistic mechanism and structure-activity relationships studies.

    PubMed

    Peng, Wei; Ding, Fei

    2015-08-30

    As the key constituent of ligand-gated ion channels in the central nervous system, nicotinic acetylcholine receptors (nAChRs) and neurodegenerative diseases are strongly coupled in the human species. In recently years the developments of selective agonists by using nAChRs as the drug target have made a large progress, but the studies of selective antagonists are severely lacked. Currently these antagonists rest mainly on the extraction of partly natural products from some animals and plants; however, the production of these crude substances is quite restricted, and artificial synthesis of nAChR antagonists is still one of the completely new research fields. In the context of this manuscript, our primary objective was to comprehensively analyze the recognition patterns and the critical interaction descriptors between target α7 nAChR and a series of the novel compounds with potentially antagonistic activity by means of virtual screening, molecular docking and molecular dynamics simulation, and meanwhile these recognition reactions were also compared with the biointeraction of α7 nAChR with a commercially natural antagonist - methyllycaconitine. The results suggested clearly that there are relatively obvious differences of molecular structures between synthetic antagonists and methyllycaconitine, while the two systems have similar recognition modes on the whole. The interaction energy and the crucially noncovalent forces of the α7 nAChR-antagonists are ascertained according to the method of Molecular Mechanics/Generalized Born Surface Area. Several amino acid residues, such as B/Tyr-93, B/Lys-143, B/Trp-147, B/Tyr-188, B/Tyr-195, A/Trp-55 and A/Leu-118 played a major role in the α7 nAChR-antagonist recognition processes, in particular, residues B/Tyr-93, B/Trp-147 and B/Tyr-188 are the most important. These outcomes tally satisfactorily with the discussions of amino acid mutations. Based on the explorations of three-dimensional quantitative structure

  2. Control of yeast mating signal transduction by a mammalian. beta. sub 2 -adrenergic receptor and G sub s. alpha. subunit

    SciTech Connect

    King, K.; Caron, M.G.; Lefkowitz, R.J. ); Dohlman, H.G.; Thorner, J. )

    1990-10-05

    To facilitate functional and mechanistic studies of receptor-G protein interactions by expression of the human {beta}{sub 2}-adrenergic receptor (h{beta}-AR) has been expressed in Saccharomyces cerevisiae. This was achieved by placing a modified h{beta}-AR gene under control of the galactose-inducible GAL1 promoter. After induction by galactose, functional h{beta}-AR was expressed at a concentration several hundred times as great as that found in any human tissue. As determined from competitive ligand binding experiments, h{beta}-AR expressed in yeast displayed characteristic affinities, specificity, and stereoselectivity. Partial activation of the yeast pheromone response pathway by {beta}-adrenergic receptor agonists was achieved in cells coexpressing h{beta}-AR and a mammalian G protein (G{sub s}) {alpha} subunit - demonstrating that these components can couple to each other and to downstream effectors when expressed in yeast. This in vivo reconstitution system provides a new approach for examining ligand binding and G protein coupling to cell surface receptors.

  3. Role of extracellular disulfide-bonded cysteines in the ligand binding function of the. beta. sub 2 -adrenergic receptor

    SciTech Connect

    Dohlman, H.G.; Caron, M.G.; DeBlasi, A.; Frielle, T.; Lefkowitz, R.J. )

    1990-03-06

    Evidence is presented for a role of disulfide bridging in forming the ligand binding site of the {beta}{sub 2}-adrenergic receptor ({beta}AR). The presence of disulfide bonds at the ligand binding site is indicated by competitive inhibition by dithiothreitol (DTT) in radioligand binding assays, by specific protection by {beta}-adrenergic ligands of these effects, and by the requirement of disulfide reduction for limit proteolysis of affinity ligand labeled receptor. The kinetics of binding inhibition by DTT suggest at least two pairs of disulfide-bonded cysteines essential for normal binding. Through site-directed mutagenesis, the authors indeed were able to identify four cysteines which are critical for normal binding affinities and for the proper expression of functional {beta}AR at the cell surface. Unexpectedly, the four cysteines required for normal ligand binding are not those located within the hydrophobic transmembrane domains of the receptor (where ligand binding is presumed to occur) but lie in the extracellular hydrophilic loops connecting these transmembrane segments. These findings indicate that in addition to the well-documented involvement of the membrane-spanning domains of the receptor in ligand binding, there is an important and previously unsuspected role of the hydrophilic extracellular domains in forming the ligand binding site.

  4. β-Adrenergic Receptor-Mediated Transactivation Of Epidermal Growth Factor Receptor Decreases Cardiomyocyte Apoptosis Through Differential Subcellular Activation of ERK1/2 and Akt

    PubMed Central

    Grisanti, Laurel A.; Talarico, Jennifer A.; Carter, Rhonda L.; Yu, Justine E.; Repas, Ashley A.; Radcliffe, Scott W.; Tang, Hoang-ai; Makarewich, Catherine A.; Houser, Steven R.; Tilley, Douglas G.

    2014-01-01

    Rationale β-adrenergic receptor (βAR)-mediated transactivation of epidermal growth factor receptor (EGFR) has been shown to relay pro-survival effects via unknown mechanisms. Objective We hypothesized that acute βAR-mediated EGFR transactivation in the heart promotes differential subcellular activation of ERK1/2 and Akt, promoting cell survival through modulation of apoptosis. Methods and Results C57BL/6 mice underwent acute i.p. injection with isoproterenol (ISO) ± AG 1478 (EGFR antagonist) to assess the impact of βAR-mediated EGFR transactivation on phosphorylation of ERK1/2 (P-ERK1/2) and Akt (P-Akt) in distinct cardiac subcellular fractions. Increased P-ERK1/2 and P-Akt were observed in cytosolic, plasma membrane and nuclear fractions following ISO stimulation. Whereas the P-ERK1/2 response was EGFR-sensitive in all fractions, the P-Akt response was EGFR-sensitive only in the plasma membrane and nucleus, results confirmed in primary rat neonatal cardiomyocytes (RNCM). βAR-mediated EGFR-transactivation also decreased apoptosis in serum-depleted RNCM, as measured via TUNEL as well as caspase 3 activity/cleavage, which were sensitive to inhibition of either ERK1/2 (PD184352) or Akt (LY-294002) signaling. Caspase 3 activity/cleavage was also sensitive to inhibition of transcription, which, with an increase in nuclear P-ERK1/2 and P-Akt in response to ISO, suggested that βAR-mediated EGFR transactivation may regulate apoptotic gene transcription. An Apoptosis PCR Array identified tnfsf10 (TRAIL) to be altered by ISO in an EGFR-sensitive manner, results confirmed via RT-PCR and ELISA measurement of both membrane-bound and soluble cardiomyocyte TRAIL levels. Conclusions βAR-mediated EGFR transactivation induces differential subcellular activation of ERK1/2 and Akt leading to increased cell survival through the modulation of caspase 3 activity and apoptotic gene expression in cardiomyocytes. PMID:24566221

  5. A Long Lasting β1 Adrenergic Receptor Stimulation of cAMP/Protein Kinase A (PKA) Signal in Cardiac Myocytes*

    PubMed Central

    Fu, Qin; Kim, Sungjin; Soto, Dagoberto; De Arcangelis, Vania; DiPilato, Lisa; Liu, Shubai; Xu, Bing; Shi, Qian; Zhang, Jin; Xiang, Yang K.

    2014-01-01

    Small-molecule, ligand-activated G protein-coupled receptors are generally thought to be rapidly desensitized within a period of minutes through receptor phosphorylation and internalization after repeated or prolonged stimulation. This transient G protein-coupled receptor activation remains at odds with many observed long-lasting cellular and physiological responses. Here, using live cell imaging of cAMP with a FRET-based biosensor and myocyte contraction assay, we show that the catecholamine-activated β1 adrenergic receptor (β1AR) continuously stimulates second messenger cAMP synthesis in primary cardiac myocytes and neurons, which lasts for more than 8 h (a decay t½ of 3.9 h) in cardiac myocytes. However, the β1AR-induced cAMP signal is counterbalanced and masked by the receptor-bound phosphodiesterase (PDE) 4D8-dependent cAMP hydrolysis. Inhibition of PDE4 activity recovers the receptor-induced cAMP signal and promotes contractile response in mouse hearts during extended periods of agonist stimulation. β1AR associates with PDE4D8 through the receptor C-terminal PDZ motif-dependent binding to synaptic-associated protein 97 (SAP97). Knockdown of SAP97 or mutation of the β1AR PDZ motif disrupts the complex and promotes sustained agonist-induced cAMP activity, PKA phosphorylation, and cardiac myocyte contraction response. Together, these findings unveil a long lasting adrenergic signal in neurons and myocytes under prolonged stimulation and an underappreciated role of PDE that is essential in classic receptor signaling desensitization and in maintaining a long lasting cAMP equilibrium for ligand-induced physiological response. PMID:24713698

  6. Alpha-1-Adrenergic Receptor Subtypes in Non-Failing and Failing Human Myocardium

    PubMed Central

    Jensen, Brian C.; Swigart, Philip M; DeMarco, Teresa; Hoopes, Charles; Simpson, Paul C.

    2009-01-01

    Background Alpha-1-adrenergic receptors (α1-ARs) play adaptive roles in the heart and protect against the development of heart failure (HF). The three α1-AR subtypes,α1A, α1B, and α1D, have distinct physiological roles in mouse heart, but very little is known about α1-subtypes in human heart. Here we test the hypothesis that the α1A and α1B subtypes are present in human myocardium, similar to the mouse, and are not down-regulated in heart failure. Methods and Results Hearts from transplant recipients and unused donors were failing (n = 12; mean EF 24%) or non-failing (n = 9; mean EF 59%), and similar in age (~44 years) and sex (~70% male). We measured the α1-AR subtypes in multiple regions of both ventricles by quantitative real-time reverse transcription PCR and radioligand binding. All three α1-AR subtype mRNAs were present, and α1A mRNA was most abundant (~65% of total α1-AR mRNA). However, only α1A and α1B binding were present, and the α1B was most abundant (60% of total). In failing hearts, α1A and α1B binding were not down-regulated, in contrast with β1-ARs. Conclusions Our data show for the first time that the α1A and α1B subtypes are both present in human myocardium, but α1D binding is not, and that the α1-subtypes are not down-regulated in HF. Since α1-subtypes in the human heart are similar to mouse, where adaptive and protective effects of α1-subtypes are most convincing, it might become feasible to treat HF with a drug targeting the α1A and/or α1B. PMID:19919991

  7. β2-adrenergic receptor polymorphisms, asthma and COPD: two large population-based studies.

    PubMed

    Thomsen, M; Nordestgaard, B G; Sethi, A A; Tybjærg-Hansen, A; Dahl, M

    2012-03-01

    The β(2)-adrenergic receptor (ADRB2) is an important regulator of airway smooth muscle tone. We tested the hypothesis that three functional polymorphisms in the ADRB2 gene (Thr164Ile, Gly16Arg and Gln27Glu) are associated with reduced lung function, asthma or chronic obstructive pulmonary disease (COPD). We first genotyped 8,971 individuals from the Copenhagen City Heart Study for all three polymorphisms. To validate our findings, we genotyped an additional 53,777 individuals from the Copenhagen General Population Study for the Thr164Ile polymorphism. We identified 60,910 Thr164Ile noncarriers, 1,822 heterozygotes and 16 homozygotes. In the Copenhagen City Heart Study, the Thr164Ile genotype was associated with reduced forced expiratory volume in 1 s (FEV(1)) % predicted (trend p = 0.01) and FEV(1)/forced vital capacity (FVC) (p = 0.001): Thr164Ile heterozygotes had 3% and 2% reduced FEV(1) % pred and FEV(1)/FVC, respectively, compared with noncarriers. The odds ratio for COPD in Thr164Ile heterozygotes was 1.46 (95% CI 1.05-2.02). In the Copenhagen General Population Study, the Thr164 genotype associated with reduced FEV(1) % pred (p = 0.04) and FEV(1)/FVC (p < 0.001): Thr164Ile homozygotes and heterozygotes had 7% and 1% reduced FEV(1) % pred and 6% and 1% reduced FEV(1)/FVC, respectively, compared with noncarriers. The odds ratios for COPD in Thr164Ile homozygotes and heterozygotes were 4.53 (95% CI 1.54-13.3) and 1.07 (95% CI 0.92-1.25), respectively. Our results suggest that ADRB2 Thr164Ile is associated with reduced lung function and increased risk of COPD in the general population. PMID:22075484

  8. β2-Adrenergic receptor ablation modulates hepatic lipid accumulation and glucose tolerance in aging mice.

    PubMed

    Shi, Yun; Shu, Zhen-Ju; Xue, Xiaoling; Yeh, Chih-Ko; Katz, Michael S; Kamat, Amrita

    2016-06-01

    Catecholamines acting through β-adrenergic receptors (β1-, β2-, β3-AR subtypes) modulate important biological responses in various tissues. Our previous studies suggest a role for increased hepatic β-AR-mediated signaling during aging as a mediator of hepatic steatosis, liver glucose output, and insulin resistance in rodents. In the current study, we have utilized β2-AR knockout (KO) and wildtype (WT) control mice to define further the role of β2-AR signaling during aging on lipid and glucose metabolism. Our results demonstrate for the first time that age-related increases in hepatic triglyceride accumulation and body weight are attenuated upon β2-AR ablation. Although no differences in plasma triglyceride, non-esterified fatty acids or insulin levels were detected between old WT and KO animals, an age-associated increase in hepatic expression of lipid homeostasis regulator Cidea was significantly reduced in old KO mice. Interestingly, we also observed a shift from reduced glucose tolerance in young adult KO animals to significantly improved glucose tolerance in old KO when compared to age-matched WT mice. These results provide evidence for an important role played by β2-ARs in the regulation of lipid and glucose metabolism during aging. The effect of β2-AR ablation on caloric intake during aging is currently not known and requires investigation. Future studies are also warranted to delineate the β2-AR-mediated mechanisms involved in the control of lipid and glucose homeostasis, especially in the context of a growing aging population. PMID:26952573

  9. Inactivation of the adrenergic receptor β2 disrupts glucose homeostasis in mice

    PubMed Central

    Fernandes, Gustavo W; Ueta, Cintia B; Fonseca, Tatiane L; Gouveia, Cecilia H A; Lancellotti, Carmen L; Brum, Patrícia C; Christoffolete, Marcelo A; Bianco, Antonio C; Ribeiro, Miriam O

    2016-01-01

    Three types of beta adrenergic receptors (ARβ1–3) mediate the sympathetic activation of brown adipose tissue (BAT), the key thermogenic site for mice which is also present in adult humans. In this study, we evaluated adaptive thermogenesis and metabolic profile of a mouse with Arβ2 knockout (ARβ2KO). At room temperature, ARβ2KO mice have normal core temperature and, upon acute cold exposure (4 °C for 4 h), ARβ2KO mice accelerate energy expenditure normally and attempt to maintain body temperature. ARβ2KO mice also exhibited normal interscapular BAT thermal profiles during a 30-min infusion of norepinephrine or dobutamine, possibly due to marked elevation of interscapular BAT (iBAT) and of Arβ1, and Arβ3 mRNA levels. In addition, ARβ2KO mice exhibit similar body weight, adiposity, fasting plasma glucose, cholesterol, and triglycerides when compared with WT controls, but exhibit marked fasting hyperinsulinemia and elevation in hepatic Pepck (Pck1) mRNA levels. The animals were fed a high-fat diet (40% fat) for 6 weeks, ARβ2KO mice doubled their caloric intake, accelerated energy expenditure, and induced Ucp1 expression in a manner similar to WT controls, exhibiting a similar body weight gain and increase in the size of white adipocytes to the WT controls. However, ARβ2KO mice maintain fasting hyperglycemia as compared with WT controls despite very elevated insulin levels, but similar degrees of liver steatosis and hyperlipidemia. In conclusion, inactivation of the ARβ2KO pathway preserves cold- and diet-induced adaptive thermogenesis but disrupts glucose homeostasis possibly by accelerating hepatic glucose production and insulin secretion. Feeding on a high-fat diet worsens the metabolic imbalance, with significant fasting hyperglycemia but similar liver structure and lipid profile to the WT controls. PMID:24868110

  10. β-arrestin-biased signaling through the β2-adrenergic receptor promotes cardiomyocyte contraction.

    PubMed

    Carr, Richard; Schilling, Justin; Song, Jianliang; Carter, Rhonda L; Du, Yang; Yoo, Sungsoo M; Traynham, Christopher J; Koch, Walter J; Cheung, Joseph Y; Tilley, Douglas G; Benovic, Jeffrey L

    2016-07-12

    β-adrenergic receptors (βARs) are critical regulators of acute cardiovascular physiology. In response to elevated catecholamine stimulation during development of congestive heart failure (CHF), chronic activation of Gs-dependent β1AR and Gi-dependent β2AR pathways leads to enhanced cardiomyocyte death, reduced β1AR expression, and decreased inotropic reserve. β-blockers act to block excessive catecholamine stimulation of βARs to decrease cellular apoptotic signaling and normalize β1AR expression and inotropy. Whereas these actions reduce cardiac remodeling and mortality outcomes, the effects are not sustained. Converse to G-protein-dependent signaling, β-arrestin-dependent signaling promotes cardiomyocyte survival. Given that β2AR expression is unaltered in CHF, a β-arrestin-biased agonist that operates through the β2AR represents a potentially useful therapeutic approach. Carvedilol, a currently prescribed nonselective β-blocker, has been classified as a β-arrestin-biased agonist that can inhibit basal signaling from βARs and also stimulate cell survival signaling pathways. To understand the relative contribution of β-arrestin bias to the efficacy of select β-blockers, a specific β-arrestin-biased pepducin for the β2AR, intracellular loop (ICL)1-9, was used to decouple β-arrestin-biased signaling from occupation of the orthosteric ligand-binding pocket. With similar efficacy to carvedilol, ICL1-9 was able to promote β2AR phosphorylation, β-arrestin recruitment, β2AR internalization, and β-arrestin-biased signaling. Interestingly, ICL1-9 was also able to induce β2AR- and β-arrestin-dependent and Ca(2+)-independent contractility in primary adult murine cardiomyocytes, whereas carvedilol had no efficacy. Thus, ICL1-9 is an effective tool to access a pharmacological profile stimulating cardioprotective signaling and inotropic effects through the β2AR and serves as a model for the next generation of cardiovascular drug development. PMID

  11. Inactivation of the adrenergic receptor β2 disrupts glucose homeostasis in mice.

    PubMed

    Fernandes, Gustavo W; Ueta, Cintia B; Fonseca, Tatiane L; Gouveia, Cecilia H A; Lancellotti, Carmen L; Brum, Patrícia C; Christoffolete, Marcelo A; Bianco, Antonio C; Ribeiro, Miriam O

    2014-06-01

    Three types of beta adrenergic receptors (ARβ1-3) mediate the sympathetic activation of brown adipose tissue (BAT), the key thermogenic site for mice which is also present in adult humans. In this study, we evaluated adaptive thermogenesis and metabolic profile of a mouse with Arβ2 knockout (ARβ2KO). At room temperature, ARβ2KO mice have normal core temperature and, upon acute cold exposure (4 °C for 4 h), ARβ2KO mice accelerate energy expenditure normally and attempt to maintain body temperature. ARβ2KO mice also exhibited normal interscapular BAT thermal profiles during a 30-min infusion of norepinephrine or dobutamine, possibly due to marked elevation of interscapular BAT (iBAT) and of Arβ1, and Arβ3 mRNA levels. In addition, ARβ2KO mice exhibit similar body weight, adiposity, fasting plasma glucose, cholesterol, and triglycerides when compared with WT controls, but exhibit marked fasting hyperinsulinemia and elevation in hepatic Pepck (Pck1) mRNA levels. The animals were fed a high-fat diet (40% fat) for 6 weeks, ARβ2KO mice doubled their caloric intake, accelerated energy expenditure, and induced Ucp1 expression in a manner similar to WT controls, exhibiting a similar body weight gain and increase in the size of white adipocytes to the WT controls. However, ARβ2KO mice maintain fasting hyperglycemia as compared with WT controls despite very elevated insulin levels, but similar degrees of liver steatosis and hyperlipidemia. In conclusion, inactivation of the ARβ2KO pathway preserves cold- and diet-induced adaptive thermogenesis but disrupts glucose homeostasis possibly by accelerating hepatic glucose production and insulin secretion. Feeding on a high-fat diet worsens the metabolic imbalance, with significant fasting hyperglycemia but similar liver structure and lipid profile to the WT controls. PMID:24868110

  12. Genetic suppression of β2-adrenergic receptors ameliorates tau pathology in a mouse model of tauopathies

    PubMed Central

    Wisely, Elena V.; Xiang, Yang K.; Oddo, Salvatore

    2014-01-01

    Accumulation of the microtubule-binding protein tau is a key event in several neurodegenerative disorders referred to as tauopathies, which include Alzheimer's disease, frontotemporal lobar degeneration, Pick's disease, progressive supranuclear palsy and corticobasal degeneration. Thus, understanding the molecular pathways leading to tau accumulation will have a major impact across multiple neurodegenerative disorders. To elucidate the pathways involved in tau pathology, we removed the gene encoding the beta-2 adrenergic receptors (β2ARs) from a mouse model overexpressing mutant human tau. Notably, the number of β2ARs is increased in brains of AD patients and epidemiological studies show that the use of beta-blockers decreases the incidence of AD. The mechanisms underlying these observations, however, are not clear. We show that the tau transgenic mice lacking the β2AR gene had a reduced mortality rate compared with the parental tau transgenic mice. Removing the gene encoding the β2ARs from the tau transgenic mice also significantly improved motor deficits. Neuropathologically, the improvement in lifespan and motor function was associated with a reduction in brain tau immunoreactivity and phosphorylation. Mechanistically, we provide compelling evidence that the β2AR-mediated changes in tau were linked to a reduction in the activity of GSK3β and CDK5, two of the major tau kinases. These studies provide a mechanistic link between β2ARs and tau and suggest the molecular basis linking the use of beta-blockers to a reduced incidence of AD. Furthermore, these data suggest that a detailed pharmacological modulation of β2ARs could be exploited to develop better therapeutic strategies for AD and other tauopathies. PMID:24626633

  13. Antagonist of prostaglandin E2 receptor 4 induces metabolic alterations in liver of mice.

    PubMed

    Li, Ning; Zhang, Limin; An, Yanpeng; Zhang, Lulu; Song, Yipeng; Wang, Yulan; Tang, Huiru

    2015-03-01

    Prostaglandin E2 receptor 4 (EP4) is one of the receptors for prostaglandin E2 and plays important roles in various biological functions. EP4 antagonists have been used as anti-inflammatory drugs. To investigate the effects of an EP4 antagonist (L-161982) on the endogenous metabolism in a holistic manner, we employed a mouse model, and obtained metabolic and transcriptomic profiles of multiple biological matrixes, including serum, liver, and urine of mice with and without EP4 antagonist (L-161982) exposure. We found that this EP4 antagonist caused significant changes in fatty acid metabolism, choline metabolism, and nucleotide metabolism. EP4 antagonist exposure also induced oxidative stress to mice. Our research is the first of its kind to report information on the alteration of metabolism associated with an EP4 antagonist. This information could further our understanding of current and new biological functions of EP4. PMID:25669961

  14. Stilbenes as κ-Selective, Non-nitrogenous Opioid Receptor Antagonists

    PubMed Central

    2015-01-01

    The natural stilbene pawhuskin A has been shown to function as an opioid receptor antagonist, with preferential binding to the κ receptor. This finding encouraged assembly of a set of analogues to probe the importance of key structural features. Assays on these compounds determined that one (compound 29) shows potent opioid receptor binding activity and significantly improved selectivity for the κ receptor. These studies begin to illuminate the structural features of these non-nitrogenous opioid receptor antagonists that are required for activity. PMID:24456556

  15. Automated microscopy of cardiac myocyte hypertrophy: a case study on the role of intracellular α-adrenergic receptors.

    PubMed

    Ryall, Karen A; Saucerman, Jeffrey J

    2015-01-01

    Traditional approaches for measuring cardiac myocyte hypertrophy have been of low throughput and subjective, limiting the scope of experimental studies designed to understand it. Here, we describe an automated image acquisition and analysis platform for studying the dynamics of cardiac myocyte hypertrophy in vitro. Image acquisition scripts record 5 × 5 mosaic images of fluorescent protein-labeled neonatal rat ventricular myocytes from each well of a 96-well plate using the microscope's automated stage and focus. Image analysis algorithms automatically segment myocyte boundaries, track myocytes, and quantify changes in shape. We describe each step of the image acquisition and analysis algorithms and provide specific examples of how to implement them using Metamorph and CellProfiler software. With this system, shape dynamics of thousands of individual cardiac myocytes can be tracked for up to a week. This imaging platform was recently applied to study reversal of cardiac myocyte hypertrophy following withdrawal of the α-adrenergic agonist phenylephrine. Hypertrophy readily reversed at low but not high levels of α-adrenergic signaling, leading to identification of an intracellular population of α-adrenergic receptors responsible for this reversibility delay. PMID:25304353

  16. Chromatographic resolution of angiotensin II receptor antagonists (sartans).

    PubMed

    Tahir, Muhammad Saqlain; Adnan, Ahmad; Syed, Quratulain

    2016-08-01

    First time a simple, sensitive and unified quantification method has been developed to analyze the complete class of angiotensin II receptor antagonists which are used in the treatment of hypertension either alone or in combination with some other drugs. The most important advantage of developed method was that the eight separate drugs can be determined on a single chromatographic system without modifications in detection wavelength and mobile phase. The drugs were separated on a Purospher Star 4.6mm×25cm, 5μm, C18 column maintained at 40°C with 1mLmin(-1) flow rate using ultra violet detection at 254nm. Good separation (Rs>2.0) was achieved in a short analysis allowing simultaneous determination of all eight sartans. The effect of variation in flow rate, detection wavelength and column oven temperature was also studied. The proposed method was statistically validated in terms of precision, accuracy, linearity, specificity and robustness. The newly developed method proved to be specific, robust and accurate for the quantification of eight sartans in commercial pharmaceutical formulations. PMID:27258943

  17. Leukotriene receptor antagonists for chronic urticaria: a systematic review

    PubMed Central

    2014-01-01

    A significant proportion of patients with chronic urticaria respond inadequately to first line treatment with antihistamines. Leukotreine receptor antagonists (LTRA) are also used for chronic urticaria, although firm recommendations on their use are lacking. We performed a systematic review of randomised trials to determine the role of LTRA in treatment of chronic urticaria. A search of PUBMED, EMBASE, SCOPUS, LILACS, the Cochrane Central Register of Controlled Trials, and the Web of Science for relevant randomized control trials or cross over studies yielded 10 eligible studies. The heterogeneity of trials were high, preventing valid meta-analysis of data. Most trials indicated that LTRA are not superior to placebo or antihistamine therapy, while combination therapy of LTRA and antihistamines appear to be more efficacious compared to antihistamine alone. The side effect profile and tolerability of this group of drugs is acceptable. The use of LTRA as monotherapy cannot be recommended. LTRA are effective add-on therapy to anti-histamines, and their use in patients responding poorly to antihistamines is justifiable. Further well designed randomized controlled trials with clear and standardized outcome measures are needed to determine the role of LTRA in chronic urticaria. PMID:24817895

  18. Side Effects of Leukotriene Receptor Antagonists in Asthmatic Children

    PubMed Central

    Erdem, Semiha Bahceci; Nacaroglu, Hikmet Tekin; Unsal Karkiner, Canan Sule; Gunay, Ilker; Can, Demet

    2015-01-01

    Background: Leukotriene receptor antagonists (LTRAs) are drugs which have been widely used more than ten years. As the use of LTRAs increases, our knowledge with respect to their side effects increases as well. Objectives: The objective of our study was to evaluat the observed side effects of LTRAs used in patients with astma. Patients and Methods: 1024 patients treated only with LTRAs owing to asthma or early wheezing were included in the study for a five-year period. The observed side effects of LTRAs in these patients were retrospectively investigated. The side effects were divided into two parts as psychiatric and non-psychiatric. Results: Among the 1024 cases included in the study, 67.5% of the patients out of 41 with side effects were male, 32.5% were female and the average age was 6.5 years. The rate of patients with asthma was 63.41% and 36.58% of the patients had early wheezing. It was determined that sex, age and diagnosis (early wheezing or asthma) of the patients were ineffective in the emergence of side effects. The average period for the emergence of side effects was the first month. It was observed that hyperactivity was the most frequently observed psychiatric side effect and that abdominal pain was the non-psychiatric side effect. Conclusions: The side effects of LTRAs were common in children. Therefore, patients must be informed at the beginning of the treatment and they must be evaluated at certain intervals. PMID:26495098

  19. Cysteinyl Leukotriene Receptor Antagonists Decrease Cancer Risk in Asthma Patients

    PubMed Central

    Tsai, Ming-Ju; Wu, Ping-Hsun; Sheu, Chau-Chyun; Hsu, Ya-Ling; Chang, Wei-An; Hung, Jen-Yu; Yang, Chih-Jen; Yang, Yi-Hsin; Kuo, Po-Lin; Huang, Ming-Shyan

    2016-01-01

    Previous in vitro and in vivo studies have demonstrated the potential of using cysteinyl leukotriene receptor antagonists (LTRAs) for chemoprevention, but this has not been investigated in any clinical setting. We therefore investigated the chemopreventive effect of LTRAs in a nationwide population-based study. From the Taiwan National Health Insurance Research Database, we enrolled adults with newly-diagnosed asthma between 2001 and 2011. Among these patients, each LTRA user was matched with five randomly-selected LTRA non-users by sex, age, asthma diagnostic year and modified Charlson Comorbidity Index score. We considered the development of cancer as the outcome. Totally, 4185 LTRA users and 20925 LTRA non-users were identified. LTRA users had a significantly lower cancer incidence rate than LTRA non-users did. Multivariable Cox regression analyses adjusting for baseline characteristics and comorbidities showed LTRA use was an independent protecting factor (hazard ratio = 0.31 [95% CI: 0.24–0.39]), and cancer risk decreased progressively with higher cumulative dose of LTRAs. In conclusion, this study revealed that the LTRA use decreased cancer risk in a dose-dependent manner in asthma patients. The chemopreventive effect of LTRAs deserves further study. PMID:27052782

  20. Applicability of DPI formulations for novel neurokinin receptor antagonist.

    PubMed

    Kumon, M; Yabe, Y; Kasuya, Y; Suzuki, M; Kusai, A; Yonemochi, E; Terada, K

    2008-05-22

    A novel triple neurokinin receptor antagonist (TNRA) could have pharmaceutical efficacy for asthma and/or chronic obstructive pulmonary disease. TNRA is potentially developed as inhalation medicine. The aim of this investigation was to evaluate the applicability of dry powder inhaler (DPI) formulation for TNRA. DPI formulation containing lactose was used for this feasibility study. Mechanofusion process for surface modification was applied on lactose particles to prepare four different DPI formulations. The mixture of TNRA and lactose was administered to rats intratracheally using an insufflator. The deposition pattern and blood concentration profile of TNRA were evaluated. Although there was no significant difference in deposition on deep lungs between the four formulations, DPI formulations containing mechanofusion-processed lactose showed longer T(max) and t(1/2) and higher AUC(0-infinity) and MRT compared to that containing intact lactose. On the other hand, the contact angle measurement showed that the mechanofusion process decreased the polar part of the surface energy of the lactose. Therefore, the prolongation of the wetting of the formulated powder mixture seemed to delay the dissolution of TNRA deposited in respiratory tract. It was concluded that DPI formulation containing mechanofusion-processed lactose could be suitable for inhalation of TNRA. PMID:18294787

  1. Bioactivation pathways of the cannabinoid receptor 1 antagonist rimonabant.

    PubMed

    Bergström, Moa Andresen; Isin, Emre M; Castagnoli, Neal; Milne, Claire E

    2011-10-01

    In the present work, the characterization of the biotransformation and bioactivation pathways of the cannabinoid receptor 1 antagonist rimonabant (Acomplia) is described. Rimonabant was approved in Europe in 2006 for the treatment of obesity but was withdrawn in 2008 because of a significant drug-related risk of serious psychiatric disorders. The aim of the present work is to characterize the biotransformation and potential bioactivation pathways of rimonabant in vitro in human and rat liver microsomes. The observation of a major iminium ion metabolite led us to perform reactive metabolite trapping, covalent binding to proteins, and time-dependent inhibition of cytochrome P450 3A4 studies. The major biotransformation pathways were oxidative dehydrogenation of the piperidinyl ring to an iminium ion, hydroxylation of the 3 position of the piperidinyl ring, and cleavage of the amide linkage. In coincubations with potassium cyanide, three cyanide adducts were detected. A high level of covalent binding of rimonabant in human liver microsomes was observed (920 pmol equivalents/mg protein). In coincubations with potassium cyanide and methoxylamine, the covalent binding was reduced by approximately 40 and 30%, respectively, whereas GSH had no significant effect on covalent binding levels. Rimonabant was also found to inhibit cytochrome P450 3A4 irreversibly in a time-dependent manner. In view of these findings, it is noteworthy that, to date, no toxicity findings related to the formation of reactive metabolites from rimonabant have been reported. PMID:21733882

  2. Cysteinyl Leukotriene Receptor Antagonists Decrease Cancer Risk in Asthma Patients.

    PubMed

    Tsai, Ming-Ju; Wu, Ping-Hsun; Sheu, Chau-Chyun; Hsu, Ya-Ling; Chang, Wei-An; Hung, Jen-Yu; Yang, Chih-Jen; Yang, Yi-Hsin; Kuo, Po-Lin; Huang, Ming-Shyan

    2016-01-01

    Previous in vitro and in vivo studies have demonstrated the potential of using cysteinyl leukotriene receptor antagonists (LTRAs) for chemoprevention, but this has not been investigated in any clinical setting. We therefore investigated the chemopreventive effect of LTRAs in a nationwide population-based study. From the Taiwan National Health Insurance Research Database, we enrolled adults with newly-diagnosed asthma between 2001 and 2011. Among these patients, each LTRA user was matched with five randomly-selected LTRA non-users by sex, age, asthma diagnostic year and modified Charlson Comorbidity Index score. We considered the development of cancer as the outcome. Totally, 4185 LTRA users and 20925 LTRA non-users were identified. LTRA users had a significantly lower cancer incidence rate than LTRA non-users did. Multivariable Cox regression analyses adjusting for baseline characteristics and comorbidities showed LTRA use was an independent protecting factor (hazard ratio = 0.31 [95% CI: 0.24-0.39]), and cancer risk decreased progressively with higher cumulative dose of LTRAs. In conclusion, this study revealed that the LTRA use decreased cancer risk in a dose-dependent manner in asthma patients. The chemopreventive effect of LTRAs deserves further study. PMID:27052782

  3. Mineralocorticoid Receptor Antagonists for Treatment of Hypertension and Heart Failure

    PubMed Central

    Sica, Domenic A.

    2015-01-01

    Spironolactone and eplerenone are both mineralocorticoid-receptor antagonists. These compounds block both the epithelial and nonepithelial actions of aldosterone, with the latter assuming increasing clinical relevance. Spironolactone and eplerenone both affect reductions in blood pressure either as mono- or add-on therapy; moreover, they each afford survival benefits in diverse circumstances of heart failure and the probability of renal protection in proteinuric chronic kidney disease. However, as use of mineralocorticoid-blocking agents has expanded, the hazards inherent in taking such drugs have become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove disastrous, even fatal, if sufficient degrees of hyperkalemia emerge. For most patients, however, the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered a possibility in patients receiving either of these medications; therefore, anticipatory steps should be taken to minimize the likelihood of its occurrence if long-term therapy of these agents is being considered. PMID:27057293

  4. Beta 2-adrenergic receptor gene association with overweight and asthma in children and adolescents and its relationship with physical fitness

    PubMed Central

    Leite, Neiva; Lazarotto, Leilane; Milano, Gerusa Eisfeld; Titski, Ana Claudia Kapp; Consentino, Cássio Leandro Mühe; de Mattos, Fernanda; de Andrade, Fabiana Antunes; Furtado-Alle, Lupe

    2015-01-01

    Objective: To investigate the association of Arg16Gly and Gln27Glu polymorphisms of β2-adrenergic receptor gene (ADRB2) with the occurrence of asthma and overweight and the gene's influence on anthropometric, clinic, biochemical and physical fitness variables in children and adolescents. Methods: Subjects were evaluated for allelic frequencies of the β2-adrenergic receptor gene, height, weight, body mass index (BMI), BMI Z-score, waist circumference (WC), pubertal stage, resting heart rate (HRres), blood pressure (BP), total cholesterol (TC), glucose, insulin, high density lipoprotein (HDL-C), low density lipoprotein (LDL-C), triglyceride (TG), Homeostasis Metabolic Assessment (HOMA2-IR), Quantitative Insulin Sensitivity Check Index (QUICKI) and maximal oxygen uptake (VO2max). The participants were divided in four groups: overweight asthmatic (n=39), overweight non-asthmatic (n=115), normal weight asthmatic (n=12), and normal weight non-asthmatic (n=40). Results: Regarding the Gln27Glu polymorphism, higher total cholesterol was observed in usual genotype individuals than in genetic variant carriers (p=0.04). No evidence was found that the evaluated polymorphisms are influencing the physical fitness. The Arg16 allele was found more frequently among the normal weight asthmatic group when compared to the normal weight non-asthmatic group (p=0.02), and the Glu27 allele was more frequently found in the overweight asthmatics group when compared to the normal weight non-asthmatic group (p=0.03). Conclusions: The association of Arg16 allele with the occurrence of asthma and of the Glu27 allele with overweight asthmatic adolescents evidenced the contribution of the β2-adrenergic receptor gene to the development of obesity and asthma. PMID:26409918

  5. Structural basis for receptor subtype-specific regulation revealed by a chimeric beta 3/beta 2-adrenergic receptor.

    PubMed Central

    Liggett, S B; Freedman, N J; Schwinn, D A; Lefkowitz, R J

    1993-01-01

    The physiological significance of multiple G-protein-coupled receptor subtypes, such as the beta-adrenergic receptors (beta ARs), remains obscure, since in many cases several subtypes activate the same effector and utilize the same physiological agonists. We inspected the deduced amino acid sequences of the beta AR subtypes for variations in the determinants for agonist regulation as a potential basis for subtype differentiation. Whereas the beta 2AR has a C terminus containing 11 serine and threonine residues representing potential sites for beta AR kinase phosphorylation, which mediates rapid agonist-promoted desensitization, only 3 serines are present in the comparable region of the beta 3AR, and they are in a nonfavorable context. The beta 3AR also lacks sequence homology in regions which are important for agonist-mediated sequestration and down-regulation of the beta 2AR, although such determinants are less well defined. We therefore tested the idea that the agonist-induced regulatory properties of the two receptors might differ by expressing both subtypes in CHW cells and exposing them to the agonist isoproterenol. The beta 3AR did not display short-term agonist-promoted functional desensitization or sequestration, or long-term down-regulation. To assign a structural basis for these subtype-specific differences in agonist regulation, we constructed a chimeric beta 3/beta 2AR which comprised the beta 3AR up to proline-365 of the cytoplasmic tail and the C terminus of the beta 2AR. When cells expressing this chimeric beta 3/beta 2AR were exposed to isoproterenol, functional desensitization was observed. Whole-cell phosphorylation studies showed that the beta 2AR displayed agonist-dependent phosphorylation, but no such phosphorylation could be demonstrated with the beta 3AR, even when beta AR kinase was overexpressed. In contrast, the chimeric beta 3/beta 2AR did display agonist-dependent phosphorylation, consistent with its functional desensitization. In

  6. Discovery and pharmacological profile of new hydrophilic 5-HT(4) receptor antagonists.

    PubMed

    Brudeli, Bjarne; Navaratnarajah, Mirusha; Andressen, Kjetil Wessel; Manfra, Ornella; Moltzau, Lise Román; Nilsen, Nils Olav; Levy, Finn Olav; Klaveness, Jo

    2014-09-15

    The synthesis and pharmacological data of some new and potent hydrophilic 5-HT4 receptor antagonists are described. Propanediol derivative 25 was identified as a potent antagonist with low affinity for the hERG potassium channel and promising pharmacokinetics. PMID:25149506

  7. Identification of potent CNS-penetrant thiazolidinones as novel CGRP receptor antagonists.

    PubMed

    Joshi, Pramod; Anderson, Corey; Binch, Hayley; Hadida, Sabine; Yoo, Sanghee; Bergeron, Danielle; Decker, Caroline; terHaar, Ernst; Moore, Jonathan; Garcia-Guzman, Miguel; Termin, Andreas

    2014-02-01

    Calcitonin gene-related peptide (CGRP) has been implicated in acute migraine pathogenesis. In an effort to identify novel CGRP receptor antagonists for the treatment of migraine, we have discovered thiazolidinone 49, a potent (Ki=30 pM, IC50=1 nM), orally bioavailable, CNS-penetrant CGRP antagonist with good pharmacokinetic properties. PMID:24405707

  8. Discovery of novel non-steroidal reverse indole mineralocorticoid receptor antagonists.

    PubMed

    Ogawa, Anthony K; Bunte, Ellen Vande; Mal, Rudrajit; Lan, Ping; Sun, Zhongxiang; Crespo, Alejandro; Wiltsie, Judyann; Clemas, Joseph; Gibson, Jack; Contino, Lisa; Lisnock, JeanMarie; Zhou, Gaochao; Garcia-Calvo, Margarita; Jochnowitz, Nina; Ma, Xiuying; Pan, Yi; Brown, Patricia; Zamlynny, Beata; Bateman, Thomas; Leung, Dennis; Xu, Ling; Tong, Xinchun; Liu, Kun; Crook, Martin; Sinclair, Peter

    2016-06-15

    Reported herein are a series of reverse indoles that represent novel non-steroidal mineralocorticoid receptor (MR) antagonists. The key structure-activity relationships (SAR) are presented below. This reverse indole series is exemplified by a compound that demonstrated efficacy in an acute natriuresis rodent model comparable to marketed MR antagonists, spironolactone and eplerenone. PMID:27161805

  9. Sphingosine-1-Phosphate Receptor-2 Antagonists: Therapeutic Potential and Potential Risks

    PubMed Central

    Blankenbach, Kira V.; Schwalm, Stephanie; Pfeilschifter, Josef; Meyer zu Heringdorf, Dagmar

    2016-01-01

    The sphingosine-1-phosphate (S1P) signaling system with its specific G-protein-coupled S1P receptors, the enzymes of S1P metabolism and the S1P transporters, offers a multitude of promising targets for drug development. Until today, drug development in this area has nearly exclusively focused on (functional) antagonists at the S1P1 receptor, which cause a unique phenotype of immunomodulation. Accordingly, the first-in class S1P1 receptor modulator, fingolimod, has been approved for the treatment of relapsing-remitting multiple sclerosis, and novel S1P1 receptor (functional) antagonists are being developed for autoimmune and inflammatory diseases such as psoriasis, inflammatory bowel disease, lupus erythematodes, or polymyositis. Besides the S1P1 receptor, also S1P2 and S1P3 are widely expressed and regulate many diverse functions throughout the body. The S1P2 receptor, in particular, often exerts cellular functions which are opposed to the functions of the S1P1 receptor. As a consequence, antagonists at the S1P2 receptor have the potential to be useful in a contrasting context and different areas of indication compared to S1P1 antagonists. The present review will focus on the therapeutic potential of S1P2 receptor antagonists and discuss their opportunities as well as their potential risks. Open questions and areas which require further investigations will be emphasized in particular. PMID:27445808

  10. Catechol-O-methlytransferase inhibition alters pain and anxiety-related volitional behaviors through activation of β-adrenergic receptors in the rat

    PubMed Central

    Kline, R. H.; Exposto, F. G.; O’Buckley, S. C.; Westlund, K. N.; Nackley, A. G.

    2015-01-01

    Reduced catechol-O-methyltransferase (COMT) activity resulting from genetic variation or pharmacological depletion results in enhanced pain perception in humans and nociceptive behaviors in animals. Using phasic mechanical and thermal reflex tests (e.g. von Frey, Hargreaves), recent studies show that acute COMT-dependent pain in rats is mediated by β-adrenergic receptors (βARs). In order to more closely mimic the characteristics of human chronic pain conditions associated with prolonged reductions in COMT, the present study sought to determine volitional pain-related and anxiety-like behavioral responses following sustained as well as acute COMT inhibition using an operant 10–45°C thermal place preference task and a light/dark preference test. In addition, we sought to evaluate the effects of sustained COMT inhibition on generalized body pain by measuring tactile sensory thresholds of the abdominal region. Results demonstrated that acute and sustained administration of the COMT inhibitor OR486 increased pain behavior in response to thermal heat. Further, sustained administration of OR486 increased anxiety behavior in response to bright light, as well as abdominal mechanosensation. Finally, all pain-related behaviors were blocked by the non-selective βAR antagonist propranolol. Collectively, these findings provide the first evidence that stimulation of ARs following acute or chronic COMT inhibition drives cognitive-affective behaviors associated with heightened pain that affects multiple body sites. PMID:25659347

  11. Inhibition of protein synthesis but not β-adrenergic receptors blocks reconsolidation of a cocaine-associated cue memory.

    PubMed

    Dunbar, Amber B; Taylor, Jane R

    2016-08-01

    Previously consolidated memories have the potential to enter a state of lability upon memory recall, during which time the memory can be altered before undergoing an additional consolidation-like process and being stored again as a long-term memory. Blocking reconsolidation of aberrant memories has been proposed as a potential treatment for psychiatric disorders including addiction. Here we investigated of the effect of systemically administering the protein synthesis inhibitor cycloheximide or the β-adrenergic antagonist propranolol on reconsolidation. Rats were trained to self-administer cocaine, during which each lever press resulted in the presentation of a cue paired with an intravenous infusion of cocaine. After undergoing lever press extinction to reduce operant responding, the cue memory was reactivated and rats were administered systemic injections of propranolol, cycloheximide, or vehicle. Post-reactivation cycloheximide, but not propranolol, resulted in a reactivation-dependent decrease in cue-induced reinstatement, indicative of reconsolidation blockade by protein synthesis inhibition. The present data indicate that systemically targeting protein synthesis as opposed to the β-adrenergic system may more effectively attenuate the reconsolidation of a drug-related memory and decrease drug-seeking behavior. PMID:27421890

  12. The K+ channel TASK1 modulates β-adrenergic response in brown adipose tissue through the mineralocorticoid receptor pathway.

    PubMed

    Pisani, Didier F; Beranger, Guillaume E; Corinus, Alain; Giroud, Maude; Ghandour, Rayane A; Altirriba, Jordi; Chambard, Jean-Claude; Mazure, Nathalie M; Bendahhou, Saïd; Duranton, Christophe; Michiels, Jean-François; Frontini, Andrea; Rohner-Jeanrenaud, Françoise; Cinti, Saverio; Christian, Mark; Barhanin, Jacques; Amri, Ez-Zoubir

    2016-02-01

    Brown adipose tissue (BAT) is essential for adaptive thermogenesis and dissipation of caloric excess through the activity of uncoupling protein (UCP)-1. BAT in humans is of great interest for the treatment of obesity and related diseases. In this study, the expression of Twik-related acid-sensitive K(+) channel (TASK)-1 [a pH-sensitive potassium channel encoded by the potassium channel, 2-pore domain, subfamily K, member 3 (Kcnk3) gene] correlated highly with Ucp1 expression in obese and cold-exposed mice. In addition, Task1-null mice, compared with their controls, became overweight, mainly because of an increase in white adipose tissue mass and BAT whitening. Task1(-/-)-mouse-derived brown adipocytes, compared with wild-type mouse-derived brown adipocytes, displayed an impaired β3-adrenergic receptor response that was characterized by a decrease in oxygen consumption, Ucp1 expression, and lipolysis. This phenotype was thought to be caused by an exacerbation of mineralocorticoid receptor (MR) signaling, given that it was mimicked by corticoids and reversed by an MR inhibitor. We concluded that the K(+) channel TASK1 controls the thermogenic activity in brown adipocytes through modulation of β-adrenergic receptor signaling. PMID:26527067

  13. Kynurenic acid amides as novel NR2B selective NMDA receptor antagonists.

    PubMed

    Borza, István; Kolok, Sándor; Galgóczy, Kornél; Gere, Anikó; Horváth, Csilla; Farkas, Sándor; Greiner, István; Domány, György

    2007-01-15

    A novel series of kynurenic acid amides, ring-enlarged derivatives of indole-2-carboxamides, was prepared and identified as in vivo active NR2B subtype selective NMDA receptor antagonists. The synthesis and SAR studies are discussed. PMID:17074483

  14. Exercise training normalizes renal blood flow responses to acute hypoxia in experimental heart failure: role of the α1-adrenergic receptor.

    PubMed

    Pügge, Carolin; Mediratta, Jai; Marcus, Noah J; Schultz, Harold D; Schiller, Alicia M; Zucker, Irving H

    2016-02-01

    Recent data suggest that exercise training (ExT) is beneficial in chronic heart failure (CHF) because it improves autonomic and peripheral vascular function. In this study, we hypothesized that ExT in the CHF state ameliorates the renal vasoconstrictor responses to hypoxia and that this beneficial effect is mediated by changes in α1-adrenergic receptor activation. CHF was induced in rabbits. Renal blood flow (RBF) and renal vascular conductance (RVC) responses to 6 min of 5% isocapnic hypoxia were assessed in the conscious state in sedentary (SED) and ExT rabbits with CHF with and without α1-adrenergic blockade. α1-adrenergic receptor expression in the kidney cortex was also evaluated. A significant decline in baseline RBF and RVC and an exaggerated renal vasoconstriction during acute hypoxia occurred in CHF-SED rabbits compared with the prepaced state (P < 0.05). ExT diminished the decline in baseline RBF and RVC and restored changes during hypoxia to those of the prepaced state. α1-adrenergic blockade partially prevented the decline in RBF and RVC in CHF-SED rabbits and eliminated the differences in hypoxia responses between SED and ExT animals. Unilateral renal denervation (DnX) blocked the hypoxia-induced renal vasoconstriction in CHF-SED rabbits. α1-adrenergic protein in the renal cortex of animals with CHF was increased in SED animals and normalized after ExT. These data provide evidence that the acute decline in RBF during hypoxia is caused entirely by the renal nerves but is only partially mediated by α1-adrenergic receptors. Nonetheless, α1-adrenergic receptors play an important role in the beneficial effects of ExT in the kidney. PMID:26607245

  15. Regulation of the beta-adrenergic receptor-adenylate cyclase complex of 3T3-L1 fibroblasts by sodium butyrate

    SciTech Connect

    Stadel, J.M.; Poksay, K.S.; Nakada, M.T.; Crooke, S.T.

    1986-05-01

    Mouse 3T3-L1 fibroblasts contain beta-adrenergic receptors (BAR), predominantly of the B/sub 1/ subtype. Incubation of these cells with 2-10 mM sodium butyrate (SB) for 24-48 hr results in a switch in the BAR subtype from B/sub 1/ to B/sub 2/ and promotes a 1.5 to 2.5 fold increase in total BAR number. Other short chain acids were not as effective as SB in promoting changes in BAR. BAR were assayed in membranes prepared from the 3T3-L1 cells using the radiolabeled antagonist (/sup 125/I)-cyanopindolol and the B/sub 2/ selective antagonist ICI 118.551. BAR subtype switch was confirmed functionally by measuring cellular cAMP accumulation in response to agonists. The structure and amount of the alpha subunits of the guanine nucleotide regulatory proteins N/sub s/ and N/sub i/ were determined by ADP-ribosylation using /sup 32/P-NAD and either cholera toxin or pertussis toxin for labeling of the respective subunits. Preincubation of cells with 5 mM SB for 48 hr resulted in a 2-3 fold increase in the labeling of the alpha subunits of both N/sub s/ and N/sub i/. A protein of M/sub r/ = 44,000 showed enhanced labeling by cholera toxin following SB treatment of the cells. These data indicate SB concomitantly regulates expression of BAR subtype and components of the adenylate cyclase in 3T3-L1 cells.

  16. QT interval prolongation and torsade de pointes: Synergistic effect of flecainide and H1 receptor antagonists

    PubMed Central

    Acosta-Materán, Carlos; Díaz-Oliva, Eloy; Fernández-Rodríguez, Diego; Hernández-Afonso, Julio

    2016-01-01

    A high percentage of patients having atrial fibrillation (AF) presents with paroxysmal AF. Flecainide, the prototypic class Ic anti-arrhythmic drug is the most effective drug to maintain sinus rhythm in this subgroup of patients, though the drug has potential pro-arrhythmic effects. Furthermore, the H1 receptor antagonists are the most commonly prescribed drugs for the symptomatic treatment of pruritus. Despite having low number of adverse effects, the H1 receptor antagonists have cardiotoxic effects. Flecainide and H1 receptor antagonists present arrhythmic complications including QT interval prolongation and torsade de pointes (TdP). The case presented here is a 65-year-old female who was diagnosed of atrial fibrillation and presented with rashes in lower extremities. The patient was treated using flecainide and H1 receptor antagonists (loratadine and hydroxyzine) that prolonged QT interval and induced TdP. The concomitant administration of flecainide and H1 receptor antagonists seems to have a synergistic effect in QT interval prolongation and subsequent TdP. The concurrent administration of H1 receptor antagonists to patients receiving class Ic anti-arrhythmic drugs should be avoided in order to reduce arrhythmic risk in this population. PMID:27440957

  17. The 2.6 Angstrom Crystal Structure of a Human A[subscript 2A] Adenosine Receptor Bound to an Antagonist

    SciTech Connect

    Jaakola, Veli-Pekka; Griffith, Mark T.; Hanson, Michael A.; Cherezov, Vadim; Chien, Ellen Y.T.; Lane, J. Robert; IJzerman, Adriaan P.; Stevens, Raymond C.

    2009-01-15

    The adenosine class of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) mediates the important role of extracellular adenosine in many physiological processes and is antagonized by caffeine. We have determined the crystal structure of the human A{sub 2A} adenosine receptor, in complex with a high-affinity subtype-selective antagonist, ZM241385, to 2.6 angstrom resolution. Four disulfide bridges in the extracellular domain, combined with a subtle repacking of the transmembrane helices relative to the adrenergic and rhodopsin receptor structures, define a pocket distinct from that of other structurally determined GPCRs. The arrangement allows for the binding of the antagonist in an extended conformation, perpendicular to the membrane plane. The binding site highlights an integral role for the extracellular loops, together with the helical core, in ligand recognition by this class of GPCRs and suggests a role for ZM241385 in restricting the movement of a tryptophan residue important in the activation mechanism of the class A receptors.

  18. Rat beta 1-adrenergic receptor regulatory region containing consensus AP-2 elements recognizes novel transactivator proteins.

    PubMed

    Kirigiti, P; Yang, Y F; Li, X; Li, B; Midson, C N; Machida, C A

    2000-03-01

    beta 1-Adrenergic receptors (beta1-ARs) serve as important regulators of central nervous system (CNS)-mediated behavior and several neural functions, including mood, memory, neuroendocrine control, and stimulation of autonomic function. Using beta 1-AR-luciferase reporter recombinants, we have previously determined that important beta 1-AR genetic elements controlling expression within the C6 glioma cell line are contained within the region -396 to -299, relative to the translational start site. By conducting progressive internal deletions of the rat beta 1-AR 5' flanking region and with the use of beta 1-AR-luciferase recombinants, we have verified that this region contains the primary beta 1-AR promoter and/or major regulatory elements. To begin the identification of protein factors involved in beta 1-AR transcriptional activity conferred by this beta 1-AR region and flanking sequences, we conducted electrophoretic mobility shift assays using defined beta 1-AR DNA subregion probes. One probe (GS-1), encompassing the region -396 to -367, was found to produce two major and two minor mobility shift complexes when bound to nuclear extracts from the beta 1-AR expresser C6 cell line. UV-crosslinking of DNA-protein complexes, coupled with DNase I digestion, indicated that this beta 1-AR region interacts with one major protein of approximately 117 kDa molecular weight and additional minor proteins. GS-1 DNA-protein complexes were observed using beta 1-AR expresser tissues in the CNS, including cortex, hippocampus, and olfactory bulb. No DNA-protein complexes were observed when using nuclear extracts from beta 1-AR nonexpresser tissues; in some cases, using L6 cells, previously characterized to express little or no beta1-ARs, a reduction in intensities of the DNA-protein complexes was observed. Competition experiments indicate that nuclear protein binds to one of two subregions within the GS-1 sequence that contain AP-2-like consensus elements. Recombinant AP-2 protein

  19. Pharmacophore modeling of dual angiotensin II and endothelin A receptor antagonists.

    PubMed

    Xue, Wei-Zhe; Lü, Wei; Zhou, Zhi-Ming; Wang, Zhan-Li

    2009-09-01

    Three-dimensional pharmacophore models were generated for AT1 and ET(A) receptors based on highly selective AT1 and ET(A) antagonists using the program Catalyst/HipHop. Both the best pharmacophore model for selective AT1 antagonists (Hypo-AT(1)-7) and ETA antagonists (Hypo-ET(A)-1) were obtained through a careful validation process. All five features contained in Hypo-AT(1)-7 and Hypo-ET(A)-1 (hydrogen-bond acceptor (A), hydrophobic aliphatic (Z), negative ionizable (N), ring aromatic (R), and hydrophobic aromatic (Y)) seem to be essential for antagonists in terms of binding activity. Dual AT1 and ET(A) receptor antagonists (DARAs) can map to both Hypo-AT(1)-7 and Hypo-ET(A)-1, separately. Comparison of Hypo-AT(1)-7 and Hypo-ET(A)-1, not only AT1 and ET(A) antagonist pharmacophore models consist of essential features necessary for compounds to be highly active and selective toward their corresponding receptor, but also have something in common. The results in this study will act as a valuable tool for designing and researching structural relationship of novel dual AT1 and ET(A) receptor antagonists. PMID:20055175

  20. Nanoscale organization of {beta}{sub 2}-adrenergic receptor-Venus fusion protein domains on the surface of mammalian cells

    SciTech Connect

    Vobornik, Dusan; Rouleau, Yanouchka; Haley, Jennifer; Bani-Yaghoub, Mahmud; Taylor, Rod; Johnston, Linda J.; Pezacki, John Paul

    2009-04-24

    Adrenergic receptors are a key component of nanoscale multiprotein complexes that are responsible for controlling the beat rate in a mammalian heart. We demonstrate the ability of near-field scanning optical microscopy (NSOM) to visualize {beta}{sub 2}-adrenergic receptors ({beta}{sub 2}AR) fused to the GFP analogue Venus at the nanoscale on HEK293 cells. The expression of the {beta}{sub 2}AR-Venus fusion protein was tightly controlled using a tetracycline-induced promoter. Both the size and density of the observed nanoscale domains are dependent on the level of induction and thus the level of protein expression. At concentrations between 100 and 700 ng/ml of inducer doxycycline, the size of domains containing the {beta}{sub 2}AR-Venus fusion protein appears to remain roughly constant, but the number of domains per cell increase. At 700 ng/ml doxycycline the functional receptors are organized into domains with an average diameter of 150 nm with a density similar to that observed for the native protein on primary murine cells. By contrast, larger micron-sized domains of {beta}{sub 2}AR are observed in the membrane of the HEK293 cells that stably overexpress {beta}{sub 2}AR-GFP and {beta}{sub 2}AR-eYFP. We conclude that precise chemical control of gene expression is highly advantageous for the use {beta}{sub 2}AR-Venus fusion proteins as models for {beta}{sub 2}AR function. These observations are critical for designing future cell models and assays based on {beta}{sub 2}AR, since the receptor biology is consistent with a relatively low density of nanoscale receptor domains.

  1. Effect of adipocyte beta3-adrenergic receptor activation on the type 2 diabetic MKR mice.

    PubMed

    Kim, Hyunsook; Pennisi, Patricia A; Gavrilova, Oksana; Pack, Stephanie; Jou, William; Setser-Portas, Jennifer; East-Palmer, Joyce; Tang, Yan; Manganiello, Vincent C; Leroith, Derek

    2006-06-01

    The antiobesity and antidiabetic effects of the beta3-adrenergic agonists were investigated on nonobese type 2 diabetic MKR mice after injection with a beta3-adrenergic agonist, CL-316243. An intact response to acute CL-316243 treatment was observed in MKR mice. Chronic intraperitoneal CL-316243 treatment of MKR mice reduced blood glucose and serum insulin levels. Hyperinsulinemic euglycemic clamps exhibited improvement of the whole body insulin sensitivity and glucose homeostasis concurrently with enhanced insulin action in liver and adipose tissue. Treating MKR mice with CL-316243 significantly lowered serum and hepatic lipid levels, in part due to increased whole body triglyceride clearance and fatty acid oxidation in adipocytes. A significant reduction in total body fat content and epididymal fat weight was observed along with enhanced metabolic rate in both wild-type and MKR mice after treatment. These data demonstrate that beta3-adrenergic activation improves the diabetic state of nonobese diabetic MKR mice by potentiation of free fatty acid oxidation by adipose tissue, suggesting a potential therapeutic role for beta3-adrenergic agonists in nonobese diabetic subjects. PMID:16682489

  2. Development of 1,3-diphenyladamantane derivatives as nonsteroidal progesterone receptor antagonists.

    PubMed

    Mori, Shuichi; Takeuchi, Yuki; Tanatani, Aya; Kagechika, Hiroyuki; Fujii, Shinya

    2015-02-15

    Nonsteroidal progesterone receptor (PR) full antagonists are needed as tools for elucidating the physiological functions of PR and as candidates for treatment of various diseases. We designed and synthesized 1,3-diphenyladamantane derivatives, and investigated their PR-antagonistic activity in comparison with our recently developed boron cluster-based PR antagonists. Among the synthesized adamantane derivatives, compound 9a exhibited the most potent PR-antagonistic activity (IC50: 25nM) and showed high binding affinity for the PR ligand-binding domain, comparable with that of the boron cluster-based PR antagonists. These results suggest that disubstituted adamantane, like the boron cluster m-carborane, is a promising hydrophobic pharmacophore for further structural development of nonsteroidal PR antagonists. PMID:25593098

  3. Association between β1 adrenergic receptor gene Arg389Gly polymorphism and risk of heart failure: a meta-analysis.

    PubMed

    Ma, S T; Zhao, W; Liu, B; Jia, R Y; Zhao, C J; Cui, L Q

    2015-01-01

    Numerous studies have evaluated the association between Arg389Gly polymorphism in the β1 adrenergic receptor gene and heart failure risk. However, the specific association is still controversial. We performed a meta-analysis of all case-control studies that evaluated the association between Arg389Gly polymorphism and heart failure in humans. Studies were identified in the PubMed, Embase, and China National Knowledge Infrastructure databases. Two reviewers independently assessed the studies. Six case-control studies with a total of 1736 participants were included in the meta-analysis, including 882 cases with heart failure and 854 controls, and our results showed no association between the Arg389Gly polymorphism and heart failure [ArgArg vs GlyGly: odds ratio (OR) = 0.84, 95% confidence interval (CI) 0.59-1.20; ArgArg vs ArgGly: OR = 0.95, 95%CI 0.78-1.16; dominant model: OR = 1.08, 95%CI 0.89-1.31; recessive model: OR = 0.96, 95%CI 0.69-1.35]. No publication bias was found in the present study (all P values > 0.05). In conclusion, the β1 adrenergic receptor gene Arg389Gly polymorphism might not be associated with heart failure risk. Further large and well-designed studies are needed to confirm this conclusion. PMID:26125791

  4. Both glutamate receptor antagonists and prefrontal cortex lesions prevent induction of cocaine sensitization and associated neuroadaptations.

    PubMed

    Li, Y; Hu, X T; Berney, T G; Vartanian, A J; Stine, C D; Wolf, M E; White, F J

    1999-12-01

    Behavioral sensitization to psychomotor stimulants is accompanied by a number of alterations in the mesoaccumbens dopamine (DA) system, including DA autoreceptor subsensitivity in the ventral tegmental area (VTA) and DA D1 receptor supersensitivity in the nucleus accumbens (NAc). We investigated the role of excitatory amino acid (EAA) transmission in the induction of cocaine sensitization and these accompanying DA receptor alterations. To do so, we used three glutamate receptor antagonists, the noncompetitive NMDA receptor antagonist MK-801 (0.1 mg/kg), the competitive NMDA receptor antagonist CGS 19755 (10.0 mg/kg), and the AMPA receptor antagonist NBQX (12.5 mg/kg). Rats received daily double injections of either one of these antagonists or saline with either cocaine (15.0 mg/kg) or saline for 5 days. Cocaine sensitization was defined as an increase in horizontal locomotor activity in response to cocaine challenge (7.5 mg/kg) on the third day of withdrawal. All three antagonists prevented the induction of cocaine sensitization. Extracellular single cell recordings revealed that these antagonists also prevented the induction of DA autoreceptor subsensitivity in the VTA and DA D1 receptor supersensitivity in the NAc. To determine whether the relevant glutamate receptors were under regulation by medial prefrontal cortex (mPFC) EAA efferents, we next lesioned the mPFC bilaterally with ibotenic acid at least 7 days before repeated cocaine treatment began. These lesions also prevented the induction of cocaine sensitization and the associated neuroadaptations. Our findings indicate that glutamate transmission from mPFC to the mesoaccumbens DA system is critical for the induction of cocaine sensitization and its cellular correlates. PMID:10523754

  5. NOP receptor mediates anti-analgesia induced by agonist-antagonist opioids.

    PubMed

    Gear, R W; Bogen, O; Ferrari, L F; Green, P G; Levine, J D

    2014-01-17

    Clinical studies have shown that agonist-antagonist opioid analgesics that produce their analgesic effect via action on the kappa-opioid receptor, produce a delayed-onset anti-analgesia in men but not women, an effect blocked by co-administration of a low dose of naloxone. We now report the same time-dependent anti-analgesia and its underlying mechanism in an animal model. Using the Randall-Selitto paw-withdrawal assay in male rats, we found that nalbuphine, pentazocine, and butorphanol each produced analgesia during the first hour followed by anti-analgesia starting at ∼90min after administration in males but not females, closely mimicking its clinical effects. As observed in humans, co-administration of nalbuphine with naloxone in a dose ratio of 12.5:1 blocked anti-analgesia but not analgesia. Administration of the highly selective kappa-opioid receptor agonist U69593 produced analgesia without subsequent anti-analgesia, and confirmed by the failure of the selective kappa antagonist nor-binaltorphimine to block nalbuphine-induced anti-analgesia, indicating that anti-analgesia is not mediated by kappa-opioid receptors. We therefore tested the role of other receptors in nalbuphine anti-analgesia. Nociceptin/orphanin FQ (NOP) and sigma-1 and sigma-2 receptors were chosen on the basis of their known anti-analgesic effects and receptor binding studies. The selective NOP receptor antagonists, JTC801, and J-113397, but not the sigma receptor antagonist, BD 1047, antagonized nalbuphine anti-analgesia. Furthermore, the NOP receptor agonist NNC 63-0532 produced anti-analgesia with the same delay in onset observed with the three agonist-antagonists, but without producing preceding analgesia and this anti-analgesia was also blocked by naloxone. These results strongly support the suggestion that clinically used agonist-antagonists act at the NOP receptor to produce anti-analgesia. PMID:24188792

  6. A Pilot Trial of Prazosin, an Alpha-1 Adrenergic Antagonist, for Comorbid Alcohol Dependence and Posttraumatic Stress Disorder

    PubMed Central

    Simpson, Tracy L.; Malte, Carol A.; Dietel, Bergetta; Tell, Dana; Pocock, Ian; Lyons, Robert; Varon, Dana; Raskind, Murray; Saxon, Andrew J.

    2015-01-01

    Background Posttraumatic Stress Disorder (PTSD) and alcohol dependence (AD) commonly co-occur and are associated with greater symptom severity and costs than either disorder alone. No pharmacologic interventions have been found to decrease both alcohol use and PTSD symptom severity relative to matched placebo. Prazosin, an alpha-1 adrenoreceptor antagonist, has demonstrated efficacy reducing PTSD and AD symptoms among individuals with one or the other disorder and may be useful in addressing comorbid PTSD/AD. Methods Prazosin and matched placebo were compared in the context of an outpatient 6-week double-blind randomized controlled pilot trial involving 30 individuals with comorbid PTSD/AD. Medication was titrated to 4mg q AM, 4mg q PM and 8mg qhs by the end of week 2. Participants in both conditions received five Medical Management sessions. Information regarding alcohol use, craving, and PTSD was gathered daily using a telephone Interactive Voice Response (IVR) system. Results Participants randomized to prazosin had a greater reduction in percent days drinking per week and percent days heavy drinking per week between baseline and week 6 than did placebo participants. No significant differences were detected within or between groups in change from weeks 1 to 6 in total PTSD symptoms. Participants in the prazosin condition reported drowsiness on significantly more days than those in the placebo condition. Conclusions Consistent with the extant research evaluating medications for comorbid PTSD/AD, the current evaluation of prazosin also found decreased alcohol consumption but no medication effect on PTSD symptomatology. PMID:25827659

  7. Alcohol- and alcohol antagonist-sensitive human GABAA receptors: tracking δ subunit incorporation into functional receptors.

    PubMed

    Meera, Pratap; Olsen, Richard W; Otis, Thomas S; Wallner, Martin

    2010-11-01

    GABA(A) receptors (GABA(A)Rs) have long been a focus as targets for alcohol actions. Recent work suggests that tonic GABAergic inhibition mediated by extrasynaptic δ subunit-containing GABA(A)Rs is uniquely sensitive to ethanol and enhanced at concentrations relevant for human alcohol consumption. Ethanol enhancement of recombinant α4β3δ receptors is blocked by the behavioral alcohol antagonist 8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylic acid ethyl ester (Ro15-4513), suggesting that EtOH/Ro15-4513-sensitive receptors mediate important behavioral alcohol actions. Here we confirm alcohol/alcohol antagonist sensitivity of α4β3δ receptors using human clones expressed in a human cell line and test the hypothesis that discrepant findings concerning the high alcohol sensitivity of these receptors are due to difficulties incorporating δ subunits into functional receptors. To track δ subunit incorporation, we used a functional tag, a single amino acid change (H68A) in a benzodiazepine binding residue in which a histidine in the δ subunit is replaced by an alanine residue found at the homologous position in γ subunits. We demonstrate that the δH68A substitution confers diazepam sensitivity to otherwise diazepam-insensitive α4β3δ receptors. The extent of enhancement of α4β3δH68A receptors by 1 μM diazepam, 30 mM EtOH, and 1 μM β-carboline-3-carboxy ethyl ester (but not 1 μM Zn(2+) block) is correlated in individual recordings, suggesting that δ subunit incorporation into recombinant GABA(A)Rs varies from cell to cell and that this variation accounts for the variable pharmacological profile. These data are consistent with the notion that δ subunit-incorporation is often incomplete in recombinant systems yet is necessary for high ethanol sensitivity, one of the features of native δ subunit-containing GABA(A)Rs. PMID:20699325

  8. Alcohol- and Alcohol Antagonist-Sensitive Human GABAA Receptors: Tracking δ Subunit Incorporation into Functional Receptors

    PubMed Central

    Meera, Pratap; Olsen, Richard W.; Otis, Thomas S.

    2010-01-01

    GABAA receptors (GABAARs) have long been a focus as targets for alcohol actions. Recent work suggests that tonic GABAergic inhibition mediated by extrasynaptic δ subunit-containing GABAARs is uniquely sensitive to ethanol and enhanced at concentrations relevant for human alcohol consumption. Ethanol enhancement of recombinant α4β3δ receptors is blocked by the behavioral alcohol antagonist 8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylic acid ethyl ester (Ro15-4513), suggesting that EtOH/Ro15-4513-sensitive receptors mediate important behavioral alcohol actions. Here we confirm alcohol/alcohol antagonist sensitivity of α4β3δ receptors using human clones expressed in a human cell line and test the hypothesis that discrepant findings concerning the high alcohol sensitivity of these receptors are due to difficulties incorporating δ subunits into functional receptors. To track δ subunit incorporation, we used a functional tag, a single amino acid change (H68A) in a benzodiazepine binding residue in which a histidine in the δ subunit is replaced by an alanine residue found at the homologous position in γ subunits. We demonstrate that the δH68A substitution confers diazepam sensitivity to otherwise diazepam-insensitive α4β3δ receptors. The extent of enhancement of α4β3δH68A receptors by 1 μM diazepam, 30 mM EtOH, and 1 μM β-carboline-3-carboxy ethyl ester (but not 1 μM Zn2+ block) is correlated in individual recordings, suggesting that δ subunit incorporation into recombinant GABAARs varies from cell to cell and that this variation accounts for the variable pharmacological profile. These data are consistent with the notion that δ subunit-incorporation is often incomplete in recombinant systems yet is necessary for high ethanol sensitivity, one of the features of native δ subunit-containing GABAARs. PMID:20699325<