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Sample records for adrenergic receptor antagonist

  1. Pharmacophore development for antagonists at α1 adrenergic receptor subtypes

    NASA Astrophysics Data System (ADS)

    Bremner, J. B.; Coban, B.; Griffith, R.

    1996-12-01

    Many receptors, including α1 adrenergic receptors, have a range of subtypes. This offers possibilities for the development of highly selective antagonists with potentially fewer detrimental effects. Antagonists developed for α1A receptors, for example, would have potential in the treatment of benign prostatic hyperplasia. As part of the molecular design process, structural features necessary for the selective affinity for α1A and α1B adrenergic receptors have been investigated. The molecular modelling software (particularly the Apex module) of Molecular Simulations, Inc. was used to develop pharmacophore models for these two subtypes. Low-energy conformations of a set of known antagonists were used as input, together with a classification of the receptor affinity data. The biophores proposed by the program were evaluated and pharmacophores were proposed. The pharmacophore models were validated by testing the fit of known antagonists, not included in the training set. The critical structural feature for selectivity between the α1A and α1B adrenergic receptor sites is the distance between the basic nitrogen atom and the centre of an aromatic ring system. This will be exploited in the design and synthesis of structurally new selective antagonists for these sites.

  2. Postnatal treatment of rats with adrenergic receptor agonists or antagonists influences differentiation of sexual behavior.

    PubMed

    Jarzab, B; Sickmöller, P M; Geerlings, H; Döhler, K D

    1987-12-01

    The aim of the study was to investigate the possible role of the adrenergic system in development and differentiation of neural centers controlling sexual behavior in adulthood. For this purpose normal and androgenized female rats were treated with the alpha 1-receptor antagonist prazosin, the alpha 2-receptor agonist clonidine, or the alpha 2-receptor antagonist yohimbine-HCl throughout the first week of life. In adulthood all animals were ovariectomized and, after appropriate hormone-priming, they were tested for the capacity to display female and male sexual behavior patterns. Alteration of adrenergic transmission during the critical postnatal period for sexual differentiation of neural centers resulted in significant changes in the capacity to express female lordosis behavior in adulthood. In nonandrogenized animals clonidine significantly reduced the capacity for lordosis behavior. In androgenized animals clonidine had the opposite effect; it attenuated the inhibitory effect of testosterone propionate (TP) on differentiation of lordosis behavior. Prazosin, which was without effect in nonandrogenized animals, also attenuated the inhibitory effect of TP on differentiation of lordosis behavior. Yohimbine was without effect in androgenized and nonandrogenized animals. There was no influence of any of the adrenergic drugs on differentiation of male sexual behavior. In conclusion, differentiation of lordosis behavior seems to be mediated or modulated via adrenergic transmission. The defeminizing effect of testosterone postnatally on the differentiation of lordosis behavior seems to be expressed via alpha 1-adrenergic transmission, and diminished adrenergic activity during the postnatal period seems to protect the developing brain against this effect of testosterone.

  3. 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.

  4. Interaction between Ca/sup + +/-channel antagonists and. cap alpha. /sub 2/-adrenergic receptors in rabbit ileal cell membrane

    SciTech Connect

    Homeidan, F.R.; Wicks, J.; Cusolito, S.; El-Sabban, M.E.; Sharp, G.W.G.; Donowitz, M.

    1986-03-05

    An interaction between Ca/sup + +/-channel antagonists and the ..cap alpha../sub 2/-adrenergic receptor on active electrolyte transport was demonstrated in rabbit ileum. Clonidine, an ..cap alpha../sub 2/-agonist, stimulated NaCl absorption apparently by Ca/sup + +/-channel antagonism since it inhibited /sup 45/Ca/sup + +/ uptake across the basolateral membrane and decreased total ileal calcium content. This stimulation was inhibited by the Ca/sup + +/-channel antagonists dl- and l-verapamil and cadmium but not by nifedipine. The binding of /sup 3/H-yohimbine, a specific ..cap alpha../sub 2/-adrenergic antagonist, was studied on purified ileal cell membranes using a rapid filtration technique. dl-Verapamil and Cd/sup + +/ inhibited the specific binding of /sup 3/H-yohimbine over the same concentration range in which they affected transport. In contrast, nifedipine had no effect on binding, just as it had no effect on clonidine-stimulated NaCl absorption. These data demonstrate that there is an interaction between Ca/sup + +/-channels and ..cap alpha../sub 2/-adrenergic receptors in ileal basolateral membranes. Some Ca/sup + +/-channel antagonists alter ..cap alpha../sub 2/-adrenergic binding to the receptor and ..cap alpha../sub 2/-agonist binding leads to changes in Ca/sup + +/ entry. A close spatial relationship between the Ca/sup + +/-channel and the ..cap alpha../sub 2/-receptor could explain the data.

  5. Selective blockade and recovery of cell surface alpha 2-adrenergic receptors in human erythroleukemia (HEL) cells. Studies with the irreversible antagonist benextramine

    SciTech Connect

    McKernan, R.M.; Strickland, W.R.; Insel, P.A.

    1988-01-01

    alpha 2-Adrenergic receptors are present on human erythroleukemia (HEL) cells, both on the cell surface and in a sequestered compartment. In the current study we show that benextramine, a hydrophilic irreversible antagonist, can be used to investigate alpha 2-adrenergic receptor compartmentation in these cells. In membranes prepared from HEL cells, benextramine competed for all alpha 2-adrenergic receptors ( (/sup 3/H)yohimbine sites). In intact cells, at 4 degrees, benextramine exhibited a biphasic competition curve for alpha 2-adrenergic receptors, with EC50 values of approximately 10 microM and greater than 1 mM for the high and low affinity components, respectively. We propose that the alpha 2-adrenergic receptors preferentially blocked by benextramine are those on the surface of the cell, whereas those with low affinity are sequestered receptors because: 1) only epinephrine-accessible sites are removed by prior treatment of cells with benextramine, 2) a preparation enriched with surface membranes is also enriched in receptors with a high affinity for benextramine; and 3) after blockade of cell surface receptors (54 +/- 6% of total sites, n = 7) by benextramine, the ability of the alpha 2-adrenergic agonists epinephrine and UK-14,304 to inhibit forskolin-stimulated cAMP accumulation is lost. The latter result implies that only cell surface and not sequestered receptors are functionally coupled to adenylate cyclase. The return of receptors from the sequestered compartment to the cell surface and the recovery of alpha 2-adrenergic receptor function were measured after HEL cells were treated with benextramine (50 microM for 1 hr at 4 degrees). The recovery of receptor binding (t1/2 = 25 min) was somewhat slower than the recovery of function (t1/2 approximately 8 min).

  6. The Specific α1-Adrenergic Receptor Antagonist Prazosin Influences the Urine Proteome

    PubMed Central

    Zhao, Mindi; Wu, Jianqiang; Gao, Youhe

    2016-01-01

    Urine, reflecting many changes in the body, is a better source than blood for biomarker discovery. However, even under physiological conditions, the urine proteome often varies. Understanding how various regulating factors affect urine proteome helps link changes to urine proteome with urinary biomarkers of physiological conditions as well as corresponding diseases. To evaluate the possible impact of α1-adrenergic receptor on urine proteome, this study investigated effects of the specific inhibitor prazosin on the urine proteome in a rat model by using tandem mass tagging and two-dimensional liquid chromatography-tandem mass spectrometry. A total of 775 proteins were identified, approximately half of which were influenced by prazosin treatment, indicating that the sympathetic nervous system exerts a significant impact on urine proteome. Eight significantly changed proteins were previously annotated as urinary candidate biomarkers. Angiotensinogen, haptoglobin, and beta-2 microglobulin, which were reported to be associated with blood pressure, were validated via Western blot. Prazosin is widely used in clinical practice; thus, these protein changes should be considered when studying corresponding diseases such as hypertension, post-traumatic stress disorder and benign prostatic hyperplasia. The related physiological activities of α1-receptors, controlling blood pressure and fear response might significantly affect the urine proteome and warrant further biomarker studies. PMID:27780262

  7. (-)(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.

  8. [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.

  9. Beta-adrenergic receptor antagonists and chronic heart failure in children

    PubMed Central

    Filippo, Sylvie Di

    2007-01-01

    Chronic congestive heart failure (HF) occurs in infants and children as a result of systemic ventricle incompetence. Neurohormonal activation is thought to be the main consequence of cardiac pump failure and cause of further worsening. Several large multicenter randomized trials have demonstrated that beta-adrenergic blocking agents can improve ventricular ejection fraction, symptoms, and survival in adults with chronic congestive HF. Current literature about pediatric HF is very scarce. The only large, multicenter, randomized, placebo-controlled pediatric trial failed to demonstrate any beneficial effect of beta-blockers in infants and children with chronic HF. Other small-size reports showed significant improvement in ejection fraction and/or clinical outcomes. The HF pediatric population is characterized by wide heterogeneicity regarding causes, underlying cardiac disease, drug pharmacokinetics, and interactions, which may account for divergences. Further large-scale studies are needed to elucidate the optimal use (indications and dosages) of beta-blockers in the management of HF in children, with particular attention to the underlying cardiac disease. PMID:18473008

  10. The alpha1-adrenergic receptor antagonists, benoxathian and prazosin, induce apoptosis and a switch towards megakaryocytic differentiation in human erythroleukemia cells.

    PubMed

    Fuchs, Robert; Stelzer, Ingeborg; Haas, Helga S; Leitinger, Gerd; Schauenstein, Konrad; Sadjak, Anton

    2009-10-01

    The erythroleukemia cell lines K562 and human erythroleukemia (HEL) are established models to study erythroid and megakaryocytic differentiation in vitro. In this study, we show that the alpha1-adrenergic antagonists, benoxathian and prazosin, inhibit the proliferation and induce apoptosis in K562 and HEL cells. Furthermore, both tested substances induced the expression of the megakaryocytic marker CD41a, whereas the expression of the erythroid marker glycophorin-a was decreased or unchanged. Even though the expression of differentiation markers was similar after benoxathian and prazosin treatment in both cell lines, endomitosis of erythroleukemia cells was observed only after prazosin treatment. So far, benoxathian and prazosin are the first described extracellular ligands, which cause megakaryocytic differentiation in K562 and HEL cells. In summary, these results indicate a possible role of alpha1-adrenergic receptor signaling in the regulation of erythroid and megakaryocytic differentiation, even though the receptor dependence of the observed effects needs further investigation.

  11. 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

  12. The alpha1 adrenergic receptor antagonist prazosin reduces heroin self-administration in rats with extended access to heroin administration.

    PubMed

    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 of dependent rats. Prazosin, an alpha1-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). Thus, prazosin appears to stimulate food intake in extended access rats by restoring meals to the normal size and duration. The data suggest that the alpha1 adrenergic system may contribute to mechanisms that promote dependence in rats with extended access.

  13. Effects of noradrenergic denervation on L-DOPA-induced dyskinesia and its treatment by α- and β-adrenergic receptor antagonists in hemiparkinsonian rats

    PubMed Central

    Barnum, Christopher J.; Bhide, Nirmal; Lindenbach, David; Surrena, Margaret A.; Goldenberg, Adam A.; Tignor, Stefanie; Klioueva, Anna; Walters, Hannah; Bishop, Christopher

    2011-01-01

    While L-3,4-dihydroxyphenylalanine (L-DOPA) remains the standard treatment for Parkinson’s disease (PD), long-term efficacy is often compromised by L-DOPA-induced dyskinesia (LID). Recent research suggests that targeting the noradrenergic (NE) system may provide relief from both PD and LID, however, most PD patients exhibit NE loss which may modify response to such strategies. Therefore this investigation aimed to characterize the development and expression of LID and the anti-dyskinetic potential of the α2- and β-adrenergic receptor antagonists idazoxan and propranolol, respectively, in rats receiving 6-OHDA lesions with (DA lesion) or without desipramaine protection (DA + NE lesion). Male Sprague–Dawley rats (N = 110) received unilateral 6-hydroxydopamine lesions. Fifty-three rats received desipramine to protect NE neurons (DA lesion) and 57 received no desipramine reducing striatal and hippocampal NE content 64% and 86% respectively. In experiment 1, the development and expression of L-DOPA-induced abnormal involuntary movements (AIMs) and rotations were examined. L-DOPA efficacy using the forepaw adjusting steps (FAS) test was also assessed in DA- and DA + NE-lesioned rats. In experiment 2, DA- and DA + NE-lesioned rats received pre-treatments of idazoxan or propranolol followed by L-DOPA after which the effects of these adrenergic compounds were observed. Results demonstrated that moderate NE loss reduced the development and expression of AIMs and rotations but not L-DOPA efficacy while anti-dyskinetic efficacy of α2- and β-adrenergic receptor blockade was maintained. These findings suggest that the NE system modulates LID and support the continued investigation of adrenergic compounds for the improved treatment of PD. PMID:21978941

  14. Effects of noradrenergic denervation on L-DOPA-induced dyskinesia and its treatment by α- and β-adrenergic receptor antagonists in hemiparkinsonian rats.

    PubMed

    Barnum, Christopher J; Bhide, Nirmal; Lindenbach, David; Surrena, Margaret A; Goldenberg, Adam A; Tignor, Stefanie; Klioueva, Anna; Walters, Hannah; Bishop, Christopher

    2012-01-01

    While L-3,4-dihydroxyphenylalanine (L-DOPA) remains the standard treatment for Parkinson's disease (PD), long-term efficacy is often compromised by L-DOPA-induced dyskinesia (LID). Recent research suggests that targeting the noradrenergic (NE) system may provide relief from both PD and LID, however, most PD patients exhibit NE loss which may modify response to such strategies. Therefore this investigation aimed to characterize the development and expression of LID and the anti-dyskinetic potential of the α2- and β-adrenergic receptor antagonists idazoxan and propranolol, respectively, in rats receiving 6-OHDA lesions with (DA lesion) or without desipramaine protection (DA+NE lesion). Male Sprague-Dawley rats (N=110) received unilateral 6-hydroxydopamine lesions. Fifty-three rats received desipramine to protect NE neurons (DA lesion) and 57 received no desipramine reducing striatal and hippocampal NE content 64% and 86% respectively. In experiment 1, the development and expression of L-DOPA-induced abnormal involuntary movements (AIMs) and rotations were examined. L-DOPA efficacy using the forepaw adjusting steps (FAS) test was also assessed in DA- and DA+NE-lesioned rats. In experiment 2, DA- and DA+NE-lesioned rats received pre-treatments of idazoxan or propranolol followed by L-DOPA after which the effects of these adrenergic compounds were observed. Results demonstrated that moderate NE loss reduced the development and expression of AIMs and rotations but not L-DOPA efficacy while anti-dyskinetic efficacy of α2- and β-adrenergic receptor blockade was maintained. These findings suggest that the NE system modulates LID and support the continued investigation of adrenergic compounds for the improved treatment of PD.

  15. Protective effect of a GRK5 polymorphism on heart failure and its interaction with beta-adrenergic receptor antagonists.

    PubMed

    Eijgelsheim, Mark; Visser, Loes E; Uitterlinden, André G; Stricker, Bruno H Ch

    2008-10-01

    EVALUATION OF: Liggett SB, Cresci S, Kelly RJ et al.: A GRK5 polymorphism that inhibits beta-adrenergic receptor signaling is protective in heart failure. Nat. Med. 14, 510-517 (2008). beta-Adrenoceptor blockade therapy was developed for the treatment of hypertension but is now also a cornerstone in the treatment of heart failure. Based on the mechanisms of action and current knowledge of pathway signaling, Ligget et al. hypothesized that genetic variants within G-protein coupled receptor kinases might alter disease course and response to beta-adrenoceptor blockade therapy. Following a multistep approach, a common variant in GRK5 was identified as being important in vitro and in vivo (mouse model) in beta-adrenergic desensitization, and was epidemiologically related to survival and therapy response in African-Americans. Although such a variety of research approaches is appealing, owing to the large number of used methods readers remain puzzled on some issues because it is not possible to give all details of each individual study. Therefore, interpretation of the overwhelming amount of results is difficult. In an era of shifting emphasis from classic hypothesis driven pharmacogenetics to genome-wide association studies, this study shows that hypothesis driven translational research is still of high value, especially in phenotypes as investigated here.

  16. Treatment of chronic heart failure with β-adrenergic receptor antagonists: a convergence of receptor pharmacology and clinical cardiology.

    PubMed

    Bristow, Michael R

    2011-10-28

    Despite the absence of a systematic development plan, β-blockers have reached the top tier of medical therapies for chronic heart failure. The successful outcome was due to the many dedicated investigators who produced, over a 30-year period, increasing evidence that β-blocking agents should or actually did improve the natural history of dilated cardiomyopathies and heart failure. It took 20 years for supportive evidence to become undeniable, at which time in 1993 the formidable drug development resources of large pharmaceutical companies were deployed into Phase 3 trials. Success then came relatively quickly, and within 8 years multiple agents were on the market in the United States and Europe. Importantly, there is ample room to improve antiadrenergic therapy, through novel approaches exploiting the nuances of receptor biology and/or intracellular signaling, as well as through pharmacogenetic targeting.

  17. 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.

  18. Administration of a selective β2 adrenergic receptor antagonist exacerbates neuropathology and cognitive deficits in a mouse model of Alzheimer's disease.

    PubMed

    Branca, Caterina; Wisely, Elena V; Hartman, Lauren K; Caccamo, Antonella; Oddo, Salvatore

    2014-12-01

    Currently, there are no available approaches to cure or slow down the progression of Alzheimer's disease (AD), which is characterized by the accumulation of extracellular amyloid-β (Aβ) deposits and intraneuronal tangles that comprised hyperphosphorylated tau. The β2 adrenergic receptors (β2ARs) are expressed throughout the cortex and hippocampus and play a key role in cognitive functions. Alterations in the function of these receptors have been linked to AD; however, these data remain controversial as apparent contradicting reports have been published. Given the current demographics of growing elderly population and the high likelihood of concurrent β-blocker use for other chronic conditions, more studies into the role of this receptor in AD animal models are needed. Here, we show that administration of ICI 118,551 (ICI), a selective β2AR antagonist, exacerbates cognitive deficits in a mouse model of AD, the 3xTg-AD mice. Neuropathologically, ICI increased Aβ levels and Aβ plaque burden. Concomitantly, ICI-treated 3xTg-AD mice showed an increase in tau phosphorylation and accumulation. Mechanistically, these changes were linked to an increase in amyloidogenic amyloid precursor protein processing. These results suggest that under the conditions used here, selective pharmacologic inhibition of β2ARs has detrimental effects on AD-like pathology in mice. Overall, these studies strengthen the notion that the link between β2ARs and AD is likely highly complex and suggest caution in generalizing the beneficial effects of β blockers on AD.

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

    PubMed Central

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

    2015-01-01

    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 the current 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 presynaptic 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

  20. (Arylpiperazinyl)cyclohexylsufonamides: discovery of alpha(1a/1d)-selective adrenergic receptor antagonists for the treatment of Benign Prostatic Hyperplasia/Lower Urinary Tract Symptoms (BPH/LUTS).

    PubMed

    Chiu, George; Li, Shengjian; Connolly, Peter J; Pulito, Virginia; Liu, Jingchun; Middleton, Steven A

    2007-06-15

    Benign Prostatic Hyperplasia/Lower Urinary Tract Symptoms (BPH/LUTS) can be effectively treated by alpha(1)-adrenergic receptor antagonists. Unfortunately, all currently marketed alpha(1) blockers produced CV related side effects that are caused by the subtype non-selective nature of the drugs. To overcome this problem, it was postulated that a alpha(1a/1d) subtype selective antagonist would bring more benefit for the treatment of BPH/LUTS. In developing selective alpha(1a/1d) ligands, (arylpiperazinyl)cyclohexylsulfonamides were synthesized and their binding profiles against three cloned human alpha(1)-adrenergic receptor subtypes were evaluated. Many compounds show equal affinity for both alpha(1a) and alpha(1d) subtypes with good selectivity against the alpha(1b) subtype. They also overcome the problem of dopamine receptor affinity that previous analogues had exhibited.

  1. 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

  2. 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.

  3. 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

  4. Effects of Combination Treatment of Alpha 1-Adrenergic Receptor Antagonists on Voiding Dysfunction: Study on Target Organs in Overactive Bladder Rats

    PubMed Central

    2016-01-01

    Purpose Overactive bladder (OAB) causes urinary urgency, usually accompanied by frequency and nocturia. Alpha 1-adrenergic receptor (α1-AR) antagonists are known to improve lower urinary tract symptoms associated with OAB. The α1-AR antagonists constitute a variety of drugs according to the receptor subtype affinity. This study investigated the efficacy of tamsulosin, naftopidil, and a combination of the two on OAB rats. Methods The OAB rat model was induced by an intraperitoneal injection of cyclophosphamide for 14 days. The experimental groups were divided into 5 groups: control group, OAB-induction group, OAB-induction and tamsulosin monotherapy group, OAB-induction and naftopidil monotherapy group, and OAB-induction and tamsulosin-naftopidil combination therapy group. For the drug-treated groups, each drug was administrated for 14 days after the OAB induction. Cystometry for urodynamic evaluation and immunohistochemical stain for c-Fos and nerve growth factor (NGF) expressions in the central micturition centers were performed. Results Increased contraction pressure and time with enhanced c-Fos and NGF expressions in the central micturition centers were found in the OAB rats. Tamsulosin suppressed contraction pressure and time while inhibiting c-Fos and NGF expressions. Naftopidil showed no significant effect and combination therapy showed less of an effect on contraction pressure and time. Naftopidil and combination therapy exerted no significant effect on the c-Fos and NGF expressions. Conclusions Tamsulosin showed the most prominent efficacy for the treatment of OAB compared to the naftopidil and combination. The combination of tamsulosin with naftopidil showed no synergistic effects on OAB; however, further studies of addon therapy might provide opportunities to find a new modality. PMID:27915481

  5. Doxazosin, an α-1-adrenergic-receptor Antagonist, for Nightmares in Patients with Posttraumatic Stress Disorder and/or Borderline Personality Disorder: a Chart Review.

    PubMed

    Roepke, Stefan; Danker-Hopfe, Heidi; Repantis, Dimitris; Behnia, Behnoush; Bernard, Florian; Hansen, Marie-Luise; Otte, Christian

    2017-01-01

    Objective: Centrally active α-1-adrenergic-receptor antagonists such as prazosin are effective in the treatment of nightmares in patients with posttraumatic stress disorder (PTSD). A pharmacological alternative is doxazosin, which has a longer half-life and fewer side effects. However, doxazosin is currently being used without solid empirical evidence. Furthermore, no study so far has assessed the effects of α-1-antagonists on nightmares in patients with borderline personality disorder (BPD). We retrospectively assessed the effectiveness of doxazosin on nightmares in PTSD and BPD. Method: A retrospective chart review of patients treated with doxazosin for trauma-associated nightmares in our clinic was performed. As in previous prazosin studies, the B2 score of the Clinician-Administered PTSD Scale (CAPS) was used as the primary outcome measure. Furthermore, the Pittsburgh Sleep Quality Index-Addendum for PTSD (PSQI-A) and sleep logs were analyzed. Results: We identified 51 patients with PTSD and/or BPD (mean age 35.7 years, 92.3% women) who received doxazosin for nightmares. Of these, 46 patients continued doxazosin over a 4-week period and 31 patients over a 12-week period. Within the 12-week period, doxazosin treatment significantly reduced nightmares regardless of PTSD/BPD. 25 percent of patients treated for 12 weeks had full remission of nightmares. PSQI-A scores indicated that additional trauma-associated sleep symptoms improved over 12 weeks. Furthermore, recuperation of sleep improved with doxazosin within the first 4 weeks of treatment. Conclusion: Doxazosin might improve trauma associated nightmares and more general sleep parameters in patients with PTSD and BPD. Randomized controlled trials are warranted.

  6. Bioisosteric phentolamine analogs as potent alpha-adrenergic antagonists.

    PubMed

    Hong, Seoung-Soo; Bavadekar, Supriya A; Lee, Sang-Il; Patil, Popat N; Lalchandani, S G; Feller, Dennis R; Miller, Duane D

    2005-11-01

    The synthesis and biological evaluation of a new series of bioisosteric phentolamine analogs are described. Replacement of the carbon next to the imidazoline ring of phentolamine with a nitrogen atom provides compounds (2, 3) that are about 1.6 times and 4.1 times more potent functionally than phentolamine on rat alpha1-adrenergic receptors, respectively. In receptor binding assays, the affinities of phentolamine and its bioisosteric analogs were determined on the human embryonic kidney (HEK) and Chinese Hamster ovary (CHO) cell lines expressing the human alpha1- and alpha2-AR subtypes, respectively. Analogs 2 and 3, both, displayed higher binding affinities at the alpha2- versus the alpha1-ARs, affinities being the least at the alpha1B-AR. Binding affinities of the methoxy ether analog 2 were greater than those of the phenolic analog 3 at all six alpha-AR subtypes. One of the nitrogen atoms in the imidazoline ring of phentolamine was replaced with an oxygen atom to give compounds 4 and 5, resulting in a 2-substituted oxazoline ring. The low functional antagonist activity on rat aorta, and binding potencies of these two compounds on human alpha1A- and alpha2A-AR subtypes indicate that a basic functional group is important for optimum binding to the alpha1- and alpha2A-adrenergic receptors.

  7. 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…

  8. 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.

  9. The effect of adrenergic agonists and antagonists on cysteine-proteinase inhibitor (cystatin) in rat saliva.

    PubMed

    Bedi, G S

    1991-01-01

    The effect of a number of adrenergic agonists and antagonists on the induction of rat salivary cystatin was investigated. A highly sensitive and specific radioimmunoassay was used to determine cystatin in rat whole saliva. Treatment for 10 consecutive days with a non-specific beta-adrenergic agonist isoproterenol, or the beta 1-adrenergic agonists dobutamine or methoxyphenamine, resulted in the induction of the salivary cystatin. Induction was also found in rats treated for 10 days with arterenol. Only trace quantities of cystatin could be detected in saliva of rats treated with the beta 2-adrenergic agonists terbutaline or salbutamol. When isoproterenol was injected concomitantly with the mixed beta-antagonist propranolol or the beta 1-adrenergic antagonists metaprolol, proctocol or atenolol the production of cystatin was totally suppressed. However, the beta 2-antagonist, ICI 118551, produced only a partial reduction in salivary cystatin induction elicited by isoproterenol. The findings suggest that the induction of salivary cystatin is regulated, in part, by beta 1-adrenergic receptor stimulation.

  10. Age-dependent regulation of depression-like behaviors through modulation of adrenergic receptor α₁A subtype expression revealed by the analysis of interleukin-1 receptor antagonist knockout mice.

    PubMed

    Wakabayashi, C; Kiyama, Y; Kunugi, H; Manabe, T; Iwakura, Y

    2011-09-29

    Interleukin-1 (IL-1) plays a crucial role in stress responses and its mRNA is induced in the brain by stress load; however, the precise role of IL-1 in higher brain functions and their abnormalities is largely unknown. Here, we report that IL-1 receptor antagonist (IL-1Ra) knockout (KO) mice, which lack IL-1Ra molecules that antagonize the IL-1 receptor, displayed anti-depression-like phenotypes in the tail suspension test (TST) and forced-swim test (FST) only at a young stage (8 weeks), whereas the phenotypes disappeared at later stages (20 and 32 weeks). These anti-depression-like phenotypes were reversed by administration of adrenergic receptor (AR) antagonists against the ARα(1), ARα(2), and ARβ subtypes. Although the contents of 5-HT, norepinephrine (NE), and dopamine (DA), which are known to be associated with major symptoms of psychiatric disorders, were not significantly different in the hippocampus or cerebral cortex between IL-1Ra KO and their wild-type (WT) littermate mice, the mRNA expression level of the ARα(1A) subtype was significantly changed in the cerebral cortex. Interestingly, the change in expression of the ARα(1A) subtype was correlated with an age-dependent alteration in the TST and FST in IL-1Ra KO mice. Furthermore, mild immobilization stress loaded on C57BL/6J male mice caused similar anti-depression-like phenotypes in the TST and FST to those observed in mutant mice. These results suggest that sustained activation of IL-1 signaling induced by gene manipulation in mutant mice affects the expression of the ARα(1A) subtype and that modification of adrenergic signaling by the IL-1 system may ultimately cause significant psychiatric abnormalities such as depression, and this mutant mouse could be regarded as a model animal of depression that specifically appears in children and adolescents.

  11. The alpha2 adrenergic receptor antagonist idazoxan, but not the serotonin-2A receptor antagonist M100907, partially attenuated reward deficits associated with nicotine, but not amphetamine, withdrawal in rats.

    PubMed

    Semenova, Svetlana; Markou, Athina

    2010-10-01

    Based on phenomenological similarities between anhedonia (reward deficits) associated with drug withdrawal and the negative symptoms of schizophrenia, we showed previously that the atypical antipsychotic clozapine attenuated reward deficits associated with psychostimulant withdrawal. Antagonism of alpha(2) adrenergic and 5-HT(2A) receptors may contribute to these effects of clozapine. We investigated here whether blockade of alpha(2) or 5-HT(2A) receptors by idazoxan and M100907, respectively, would reverse anhedonic aspects of psychostimulant withdrawal. Idazoxan treatment facilitated recovery from spontaneous nicotine, but not amphetamine, withdrawal by attenuating reward deficits and increase the number of somatic signs. Thus, alpha(2) adrenoceptor blockade may have beneficial effects against nicotine withdrawal and may be involved in the effects of clozapine previously observed. M100907 worsened the anhedonia associated with nicotine and amphetamine withdrawal, suggesting that monotherapy with M100907 may exacerbate the expression of the negative symptoms of schizophrenia or nicotine withdrawal symptoms in people, including schizophrenia patients, attempting to quit smoking.

  12. Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) Studies on α1A-Adrenergic Receptor Antagonists Based on Pharmacophore Molecular Alignment

    PubMed Central

    Zhao, Xin; Chen, Minsheng; Huang, Biyun; Ji, Hong; Yuan, Mu

    2011-01-01

    The α1A-adrenergic receptor (α1A-AR) antagonist is useful in treating benign prostatic hyperplasia, lower urinary tract symptoms, and cardiac arrhythmia. Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed on a set of α1A-AR antagonists of N-aryl and N-nitrogen class. Statistically significant models constructed from comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were established based on a training set of 32 ligands using pharmacophore-based molecular alignment. The leave-oneout cross-validation correlation coefficients were q2 CoMFA = 0.840 and q2 CoMSIA = 0.840. The high correlation between the cross-validated/predicted and experimental activities of a test set of 12 ligands revealed that the CoMFA and CoMSIA models were robust (r2 pred/CoMFA = 0.694; r2 pred/CoMSIA = 0.671). The generated models suggested that electrostatic, hydrophobic, and hydrogen bonding interactions play important roles between ligands and receptors in the active site. Our study serves as a guide for further experimental investigations on the synthesis of new compounds. Structural modifications based on the present 3D-QSAR results may lead to the discovery of other α1A-AR antagonists. PMID:22072933

  13. Muscarinic Receptor Antagonists.

    PubMed

    Matera, Maria Gabriella; Cazzola, Mario

    2017-01-01

    Parasympathetic activity is increased in patients with chronic obstructive pulmonary disease (COPD) and asthma and appears to be the major reversible component of airway obstruction. Therefore, treatment with muscarinic receptor antagonists is an effective bronchodilator therapy in COPD and also in asthmatic patients. In recent years, the accumulating evidence that the cholinergic system controls not only contraction by airway smooth muscle but also the functions of inflammatory cells and airway epithelial cells has suggested that muscarinic receptor antagonists could exert other effects that may be of clinical relevance when we must treat a patient suffering from COPD or asthma. There are currently six muscarinic receptor antagonists licenced for use in the treatment of COPD, the short-acting muscarinic receptor antagonists (SAMAs) ipratropium bromide and oxitropium bromide and the long-acting muscarinic receptor antagonists (LAMAs) aclidinium bromide, tiotropium bromide, glycopyrronium bromide and umeclidinium bromide. Concerns have been raised about possible associations of muscarinic receptor antagonists with cardiovascular safety, but the most advanced compounds seem to have an improved safety profile. Further beneficial effects of SAMAs and LAMAs are seen when added to existing treatments, including LABAs, inhaled corticosteroids and phosphodiesterase 4 inhibitors. The importance of tiotropium bromide in the maintenance treatment of COPD, and likely in asthma, has spurred further research to identify new LAMAs. There are a number of molecules that are being identified, but only few have reached the clinical development.

  14. 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.

  15. 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.

  16. 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.

  17. Effects of the CRF receptor antagonist D-Phe CRF(12-41) and the α2-adrenergic receptor agonist clonidine on stress-induced reinstatement of nicotine-seeking behavior in rats

    PubMed Central

    Zislis, George; Desai, Tina V.; Prado, Melissa; Shah, Hina P.; Bruijnzeel, Adrie W.

    2008-01-01

    Summary Tobacco dependence is a chronic disorder that is characterized by relapse after periods of abstinence. It has been hypothesized that the activation of brain stress systems mediates stress-induced relapse to smoking. The aim of these experiments was to investigate the role of corticotropin-releasing factor (CRF) and norepinephrine in stress-induced reinstatement of extinguished nicotine-seeking behavior. Rats were allowed to self-administer nicotine under a fixed-ratio 5 schedule for 14 days and then nicotine-seeking behavior was extinguished by substituting saline for nicotine. In the first experiment, footshocks reinstated extinguished nicotine-seeking behavior. In the second experiment, there was a trend for the CRF1/2 receptor antagonist D-Phe CRF(12-41) (5, 25 μg, icv) to decrease stress-induced reinstatement of nicotine-seeking behavior. Footshock-induced reinstatement of nicotine-seeking behavior was observed only in a subset of stress-responsive rats (71%). D-Phe CRF(12-41) significantly attenuated stress-induced reinstatement of nicotine-seeking behavior in this subset of rats. In the third experiment, the α2-adrenergic receptor agonist clonidine (20, 40 μg/kg, sc) attenuated footshock-induced reinstatement of nicotine-seeking behavior. In the fourth experiment, the effects of D-Phe CRF(12-41) and clonidine on responding for chocolate-flavored food pellets was investigated in order to determine if these compounds have sedative effects. D-Phe CRF(12-41) did not affect responding for food pellets. Clonidine slightly, but significantly, decreased responding for food pellets. Clonidine decreased responding for food to a lesser degree than it decreased stress-induced reinstatement of nicotine-seeking behavior. These data provide support for the hypothesis that an increased activity of brain CRF and norepinephrine systems mediates stress-induced relapse to nicotine-seeking behavior. PMID:17976662

  18. 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

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

    PubMed

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

    2014-08-01

    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.

  20. Effects of beta-adrenergic antagonist, propranolol on spatial memory and exploratory behavior in mice.

    PubMed

    Sun, Huaying; Mao, Yu; Wang, Jianhong; Ma, Yuanye

    2011-07-08

    The beta-adrenergic system has been suggested to be involved in novelty detection and memory modulation. The present study aimed to investigate the role of beta-adrenergic receptors on novelty-based spatial recognition memory and exploratory behavior in mice using Y-maze test and open-field respectively. Mice were injected with three doses of beta-adrenergic receptor antagonist, propranolol (2, 10 and 20 mg/kg) or saline at three different time points (15 min prior to training, immediately after training and 15 min before test). The results showed that higher doses of propranolol (10 and 20 mg/kg) given before the training trial impaired spatial recognition memory while those injected at other two time points did not. A detailed analysis of exploratory behavior in open-field showed that lower dose (2 mg/kg) of propranolol reduced exploratory behavior of mice. Our findings indicate that higher dose of propranolol can impair acquisition of spatial information in the Y-maze without altering locomotion, suggesting that the beta-adrenergic system may be involved in modulating memory processes at the time of learning.

  1. Photoaffinity labeling the. beta. -adrenergic receptor with an iodoazido derivative of norepinephrine

    SciTech Connect

    Resek, J.F.

    1989-01-01

    The {beta}-adrenergic receptor is an integral membrane protein coupled to adenylate cyclase by the guanine nucleotide binding protein, Gs. Agonist binding to the receptor results in coupling the receptor to Gs, increased adenylate cyclase activity, and receptor desensitization. In contrast, antagonists bind but do not activate the receptor or result in desensitization. To study the structure and regulation of the {beta}-adrenergic receptor in the membrane, it is useful to develop ligands which covalently label the binding site. In this thesis the synthesis and characterization of the first agonist photolabel for the {beta}-adrenergic receptor is presented. The agonist photoaffinity label, N-(p-azido-m-iodophenethylamidoisobutyl)-norepinephrine (NAIN), was synthesized in non-radioactive and radioactive carrier-free forms with {sup 125}I (2,200 Ci/mmole). NAIN was chemically characterized by TLC mobility, melting point, NMR, IR, and Mass Spectroscopy. NAIN was shown to be competitive with the {beta}-adrenergic ligand ({sup 125}I)-ICYP in several membranes containing {beta}-adrenergic receptors. Binding data indicated that NAIN coupled the receptor to Gs and had an affinity for the receptor which was similar to isoproterenol. NAIN stimulated adenylate cyclase activity in guinea pig lung and S49 WT mouse lymphoma cell membranes with a K{sub act} and V max similar to isoproterenol while in frog erythrocyte ghosts, NAIN produced 77% of the maximally stimulated adenylate cyclase activity of isoproterenol. These data show that NAIN is an agonist for the {beta}-adrenergic receptor.

  2. Management of beta-adrenergic blocker and calcium channel antagonist toxicity.

    PubMed

    Kerns, William

    2007-05-01

    State-of-the-art therapy for beta-adrenergic receptor blocker and calcium channel antagonist toxicity is reviewed in the light of new insights into drug-induced shock. A brief discussion of pathophysiology, including cardiac, hemodynamic, and metabolic effects of cardiac drug toxicity, provides a foundation for understanding the basis of therapy. The major focus of this review is a critical evaluation of antidotal use of calcium, glucagon, catecholamines, insulin-euglycemia, and other novel therapies based on investigational studies and cumulative clinical experience.

  3. The Principles of Ligand Specificity on beta-2-adrenergic receptor

    PubMed Central

    Chan, H. C. Stephen; Filipek, Slawomir; Yuan, Shuguang

    2016-01-01

    G protein-coupled receptors are recognized as one of the largest families of membrane proteins. Despite sharing a characteristic seven-transmembrane topology, G protein-coupled receptors regulate a wide range of cellular signaling pathways in response to various physical and chemical stimuli, and prevail as an important target for drug discovery. Notably, the recent progress in crystallographic methods led to a breakthrough in elucidating the structures of membrane proteins. The structures of β2-adrenergic receptor bound with a variety of ligands provide atomic details of the binding modes of agonists, antagonists and inverse agonists. In this study, we selected four representative molecules from each functional class of ligands and investigated their impacts on β2-adrenergic receptor through a total of 12 × 100 ns molecular dynamics simulations. From the obtained trajectories, we generated molecular fingerprints exemplifying propensities of protein-ligand interactions. For each functional class of compounds, we characterized and compared the fluctuation of the protein backbone, the volumes in the intracellular pockets, the water densities in the receptors, the domain interaction networks as well as the movements of transmembrane helices. We discovered that each class of ligands exhibits a distinct mode of interactions with mainly TM5 and TM6, altering the shape and eventually the state of the receptor. Our findings provide insightful prospective into GPCR targeted structure-based drug discoveries. PMID:27703221

  4. Oral phentolamine: an alpha-1, alpha-2 adrenergic antagonist for the treatment of erectile dysfunction.

    PubMed

    Goldstein, I

    2000-03-01

    Phentolamine mesylate is an alpha-1 and alpha-2 selective adrenergic receptor antagonist which has undergone clinical trials for erectile dysfunction treatment. Biochemical and physiological studies in human erectile tissue have revealed a high affinity of phentolamine for alpha-1 and alpha-2 adrenergic receptors. Based on pharmacokinetic studies, it is suggested that 30-40 min following oral ingestion of 40 or 80 mg of phentolamine (Vasomax), the mean plasma phentolamine concentrations are sufficient to occupy the alpha-1 and -2 adrenergic receptors in erectile tissue and thereby result in inhibition of adrenergic-mediated physiologic activity. In large multi-center, placebo-controlled pivotal phase III clinical trials, the mean change in the erectile function domain of the International Index of Erectile Function scores (Questions 1-5 and 15) from screening to the end of treatment was significantly higher following use of active drug (40 mg and 80 mg) compared to placebo. Three to four times as many patients receiving phentolamine reported being satisfied or very satisfied compared with those receiving placebo. At doses of 40 mg and 80 mg respectively, 55% and 59% of men were able to achieve vaginal penetration with 51% and 53% achieving penetration on 75% of attempts. The correction of erectile dysfunction or improvement to a less severe category of dysfunction was experienced by 53% of men with the 80 mg dose and 40% with the 40 mg dose of phentolamine. All trends of response were the same regardless of any concomitant medication. There were no severe adverse events. At 40 mg, 7.7% experienced rhinitis and fewer than 3.1% experienced any other side effect of treatment. Phentolamine is safe, well tolerated and efficacious for the treatment of erectile dysfunction.

  5. The alpha(2C)-adrenergic receptor mediates hyperactivity of coloboma mice, a model of attention deficit hyperactivity disorder.

    PubMed

    Bruno, Kristy J; Hess, Ellen J

    2006-09-01

    Drugs that modify noradrenergic transmission such as atomoxetine and clonidine are increasingly prescribed for the treatment of attention deficit hyperactivity disorder (ADHD). However, the therapeutic targets of these compounds are unknown. Norepinephrine is also implicated in the hyperactivity exhibited by coloboma mice. To identify the receptor subtypes that regulate the hyperactivity, coloboma mice were systematically challenged with adrenergic drugs. The beta-adrenergic receptor antagonist propranolol and the alpha(1)-adrenergic receptor antagonist prazosin each had little effect on the hyperactivity. Conversely, the alpha(2)-adrenergic receptor antagonist yohimbine reduced the activity of coloboma mice but not control mice. Subtype-selective blockade of alpha(2C)-, but not alpha(2A)- or alpha(2B)-adrenergic receptors, ameliorated hyperactivity of coloboma mice without affecting activity of control mice, suggesting that alpha(2C)-adrenergic receptors mediate the hyperactivity. Localized in the basal ganglia, alpha(2C)-adrenergic receptors are in a prime position to impact locomotor activity and are, therefore, potential targets of pharmacotherapy for ADHD.

  6. Agonist photoaffinity label for the. beta. -adrenergic receptor

    SciTech Connect

    Resek, J.F.; Ruoho, A.E.

    1987-05-01

    An iodinated photosensitive derivative of norepinephrine, N-(p-azido-m-iodophenethylamidoisobutyryl)norepinephrine (NAIN), has been synthesized and characterized. Carrier-free radioiodinated NAIN ((/sup 125/I)-NAIN) was used at 1-2 x 10/sup -9/ M to photoaffinity label the ..beta..-adrenergic receptor in guinea pig lung membranes. SDS-PAGE analysis of (-)-alprenolol (10/sup -5/M) protectable (/sup 125/I)-NAIN labeling showed the same molecular weight polypeptide (65 kDa) that was specifically derivatized with the antagonist photolabel, (/sup 125/I)-IABP. Specific labeling of the ..beta..-adrenergic receptor with (/sup 125/I)-NAIN was dependent on the presence of MgCl/sub 2/ and the absence of guanyl nucleotide. GTP..gamma..S (10/sup -4/ M) abolished specific receptor labeling by (/sup 125/I)-NAIN. N-ethylmaleimide (2 mm) in the presence of (/sup 125/I)-NAIN protected against the guanyl nucleotide effect. These data are consistent with photolabeling by (/sup 125/I)-NAIN while the agonist, receptor, and GTP binding protein are in a high affinity complex.

  7. 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.

  8. Effect of β-adrenergic antagonists on in-hospital mortality after ischemic stroke

    PubMed Central

    Phelan, Christopher; Alaigh, Vivek; Fortunato, Gil; Staff, Ilene; Sansing, Lauren

    2015-01-01

    Background Ischemic stroke accounts for 85–90% of all strokes and currently has very limited therapeutic options. Recent studies of β-adrenergic antagonists suggest they may have neuroprotective effects that lead to improved functional outcomes in rodent models of ischemic stroke, however there is limited data in patients. We aimed to determine whether there was an improvement in mortality rates among patients who were taking β-blockers during the acute phase of their ischemic stroke. Methods A retrospective analysis of a prospectively collected database of ischemic stroke patients was performed. Patients who were on β-adrenergic antagonists both at home and during the first three days of hospitalization were compared to patients who were not on β-adrenergic antagonists to determine the association with patient mortality rates. Results The study included a patient population of 2804 patients. In univariate analysis, use of β-adrenergic antagonists was associated with older age, atrial fibrillation, hypertension and more severe initial stroke presentation. Despite this, multivariable analysis revealed a reduction in in-hospital mortality among patients who were treated with β-adrenergic antagonists (odds ratio 0.657; 95% confidence interval 0.655–0.658). Conclusions The continuation of home β-adrenergic antagonist medication during the first three days of hospitalization after an ischemic stroke is associated with a decrease in patient mortality. This supports the work done in rodent models suggesting neuroprotective effects of β-blockers after ischemic stroke. PMID:26163891

  9. 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.

  10. Distribution of beta-adrenergic receptors on human lymphocyte subpopulations.

    PubMed Central

    Pochet, R; Delespesse, G; Gausset, P W; Collet, H

    1979-01-01

    A technique is described allowing the quantification and the characterization of specific beta-adrenergic receptors in intact living human lymphocytes. 125I-Iodohydroxybenzylpindolol, a potent beta-adrenergic antagonist was used to label specific binding sites on unfractionated lymphoid cells and on purified subpopulations of T (F1 and F2) and B cells. F1 and F2 were obtained by filtration through nylon wool column as previously described (Delespesse et al., 1976), they differ in their response to mitogens, and in their interactions with adherent cells and B cells. 125I-HYP binding to unfractionated lymphocytes was a saturable, stereospecific and rapid process with a dissociation constant of 2.5 10(-10) M and a binding capacity of 400--600 sites/cell. Bindings on unfractionated lymphocytes, purified B cells and T cells of the F2 fraction were similar. No detectable binding was noted on T cells from the F1 fraction. Enriched T cells obtained by a rosetting technique displayed 200 receptors/cell. PMID:43789

  11. Synthesis and structure-activity relationships of a new model of arylpiperazines. 5. Study of the physicochemical influence of the pharmacophore on 5-HT(1a)/alpha(1)-adrenergic receptor affinity: synthesis of a new derivative with mixed 5-HT(1a)/d(2) antagonist properties.

    PubMed

    López-Rodríguez, M L; Morcillo, M J; Fernández, E; Porras, E; Orensanz, L; Beneytez, M E; Manzanares, J; Fuentes, J A

    2001-01-18

    In this paper we have designed and synthesized a test series of 32 amide arylpiperazine derivatives VI in order to gain insight into the physicochemical influence of the pharmacophores of 5-HT(1A) and alpha(1)-adrenergic receptors. The training set was designed applying a fractional factorial design using six physicochemical descriptors. The amide moiety is a bicyclohydantoin or a diketopiperazine (X = -(CH(2))(3)-, -(CH(2))(4)-; m = 0, 1), the spacer length is 3 or 4 methylene units, which are the optimum values for both receptors, and the aromatic substituent R occupies the ortho- or meta-position and has been selected from a database of 387 substituents using the EDISFAR program. The 5-HT(1A) and alpha(1)-adrenergic receptor binding affinities of synthesized compounds VI (1-32) have been determined. This data set has been used to derive classical quantitative structure-activity relationships (QSAR) and neural networks models for both receptors (following paper). A comparison of these models gives information for the design of the new ligand EF-7412 (46) (5-HT(1A): K(i) = 27 nM; alpha(1): K(i) > 1000 nM). This derivative displays affinity for the dopamine D(2) receptor (K(i) = 22 nM) and is selective versus all other receptors examined (5-HT(2A), 5-HT(3), 5-HT(4) and Bz; K(i) > 1000 nM). EF-7412 (46) acts as an antagonist in vivo in pre- and postsynaptic 5-HT(1A) receptor sites and as an antagonist in the dopamine D(2) receptor. Thus, EF-7412 (46) is a derivative with mixed 5-HT(1A)/D(2) antagonist properties and this derivative could be useful as a pharmacological tool.

  12. 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.

  13. Effect of dehydroleucodine on intestinal transit: structural basis of the interaction with the α(2)-adrenergic receptor.

    PubMed

    Wendel, Graciela Haydée; María, Alejandra Olivia; Aguilar, Carlos Fernando; Pelzer, Lilian Eugenia

    2011-08-01

    The activity of dehydroleucodine, a sesquiterpene lactone obtained from Artemisia douglasiana, was studied in mice small intestinal transit. Its mechanism was evaluated in the presence of several adrenergic and cholinergic antagonist drugs and one opioid antagonist. Docking of dehydroleucodine into the homology model of the α2-adrenergic receptor allowed us to analyze the structural basis of their interactions. The experiments showed that dehydroleucodine delayed intestinal transit. The docking of dehydroleucodine showed a unique binding site, equivalent to the binding site of carozolol in the β-adrenergic receptor. The results suggested that dehydroleucodine produced an inhibitory effect on intestinal transit. Its action could be mediated, at least in part, through the α2-adrenergic receptor.

  14. Pharmacologic specificity of alpha-2 adrenergic receptor subtypes

    SciTech Connect

    Petrash, A.; Bylund, D.

    1986-03-01

    The authors have defined alpha-2 adrenergic receptor subtypes in human and rat tissues using prazosin as a subtype selective drug. Prazosin has a lower affinity (250 nM) at alpha-2A receptor and a higher affinity (5 nM) at alpha-2B receptors. In order to determine if other adrenergic drugs are selective for one or the other subtypes, the authors performed (/sup 3/H)yohimbine inhibition experiments with various adrenergic drugs in tissues containing alpha-2A, alpha-2B or both subtypes. Oxymetazoline, WB4101 and yohimbine were found to be 80-, 20- and 10-fold more potent at alpha-2A receptors than at alpha-2B receptors. Phentolamine, adazoxan, (+)- and (-)-mianserin, clonidine, (+)-butaclamol, (-)- and (+)-norepinephrine, epinephrine, dopamine and thioridazine were found to have equal affinities for the two subtypes. These results further validate the subdivision of alpha-2 adrenergic receptors into alpha-2A and alpha-2B subtypes.

  15. Altered adrenergic response and specificity of the receptors in rat ascites hepatoma AH130.

    PubMed

    Sanae, F; Miyamoto, K; Koshiura, R

    1989-11-15

    Adenylate cyclase activation through adrenergic receptors in rat ascites hepatoma (AH) 130 cells in response to adrenergic drugs was studied, and receptor binding and displacement were compared with those of normal rat hepatocytes. Epinephrine (Epi) and norepinephrine (NE) activated AH130 adenylate cyclase about half as much as isoproterenol (IPN) but equaled IPN after treatment with the alpha-antagonist phentolamine or islet-activating protein (IAP). The three catecholamines in hepatocytes were similar regardless of phentolamine or IAP. These catecholamines activated adenylate cyclase in order of IPN greater than NE greater than Epi in AH130 cells but IPN greater than Epi greater than NE in hepatocytes. We then used the alpha 1-selective ligand [3H]prazosin, the alpha 2-selective ligand [3H]clonidine, and the beta-ligand [125I]iodocyanopindolol [( 125I]ICYP), and found that AH130 cells had few prazosin-binding sites, about eight times as many clonidine-binding sites with high affinity, and many more ICYP-binding sites than in hepatocytes. The dissociation constant (Ki) of the beta 1-selective drug metoprolol by Hofstee plots for AH130 cells was lower than that for hepatocytes. The inhibition of specific ICYP binding by the beta 2-selective agonist salbutamol for AH130 cells gave only one Ki value which was much higher than both high and low Ki values of the drug for hepatocytes. These findings indicate that the alpha- and beta-adrenergic receptors in hepatocytes are predominantly alpha 1-type and beta 2-type, but that those in AH130 cells are predominantly alpha 2-type and beta 1-type, and the low adrenergic response of AH130 cells is due to the dominant appearance of alpha 2-adrenergic receptors, linked with the inhibitory guanine-nucleotide binding regulatory protein, instead of alpha 1-adrenergic receptors, and beta 1-adrenergic receptors with low affinity for the hormone.

  16. Present state of alpha- and beta-adrenergic drugs I. The adrenergic receptor.

    PubMed

    Ahlquist, R P

    1976-11-01

    The cardiovascular alpha adrenergic receptors evoke vasoconstriction, the cardiovascular beta receptors evoke vasodilation and cardiac stimulation. All blood vessels have both alpha and beta receptors. In some areas, for example skin and kidney, the alpha receptors predominate. In some vascular beds, for example the nutrient vessels in skeletal muscle, beta receptors predominate. In other beds, such as coronary, visceral, and connective tissue both receptors are active. The cardiovascular effects of adrenergic agonists depend on which receptor they act on. Phenylephrine is specific for alpha receptors. Isoproterenol is specific for beta receptors. Epinephrine and norepinephrine act on both. The real value of knowing the receptor specificity of each agonist is that side effects can more easily be predicted. For example, adrenergic cardiac stimulants are antiasthmatics. Therefore, adrenergic antiasthmatics can produce excessive cardiac stimulation. For the future, agonists that are not only receptor-specific but also tissue-specific will be developed. The first of these in the United States is terbutaline. The rest of the world has in addition a similar drug, salbutamol. No one knows if this drug will be approved for use by American physicians.

  17. 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.

  18. Developmental changes of beta-adrenergic receptor-linked adenylate cyclase of rat liver

    SciTech Connect

    Katz, M.S.; Boland, S.R.; Schmidt, S.J.

    1985-06-01

    beta-Adrenergic agonist-sensitive adenylate cyclase activity and binding of the beta-adrenergic antagonist(-)-(/sup 125/I)iodopindolol were studied in rat liver during development of male Fischer 344 rats ages 6-60 days. In liver homogenates maximum adenylate cyclase response to beta-adrenergic agonist (10(-5) M isoproterenol or epinephrine) decreased by 73% (P less than 0.01) between 6 and 60 days, with most of the decrease (56%; P less than 0.01) occurring by 20 days. beta-adrenergic receptor density (Bmax) showed a corresponding decrease of 66% (P less than 0.01) by 20 days without subsequent change. Binding characteristics of stereospecificity, pharmacological specificity, saturability with time, and reversibility were unchanged with age. GTP-, fluoride-, forskolin-, and Mn2+-stimulated adenylate cyclase activities also decreased during development, suggesting a decrease of activity of the catalytic component and/or guanine nucleotide regulatory component of adenylate cyclase. These results indicate that the developmental decrease of beta-adrenergic agonist-sensitive adenylate cyclase activity may result from decreased numbers of beta-adrenergic receptors. Developmental alterations of nonreceptor components of the enzyme may also contribute to changes of catecholamine-sensitive adenylate cyclase.

  19. Alpha 1 adrenergic receptors in canine lower genitourinary tissues: insight into development and function

    SciTech Connect

    Shapiro, E.; Lepor, H.

    1987-10-01

    Radioligand receptor binding methods were used to characterize the alpha 1-adrenergic receptor in the bladder body, bladder base, prostate and urethra of the male dog. Saturation experiments were performed in tissue homogenates using (/sup 125/iodine)-Heat, an alpha 1-adrenergic antagonist of high specific activity (2,200 Ci. per mmol.). The equilibrium dissociation constant Kd for (/sup 125/iodine)-Heat binding in the bladder body (0.56 pM.), bladder base (0.81 +/- 0.11 pM.), prostate (0.86 +/- 0.19 pM.) and urethra (0.55 pM.) was similar, suggesting homogeneity of alpha 1-adrenergic binding sites in lower genitourinary tissues. The receptor density in the bladder body, bladder base, prostate and urethra, expressed as fmol. per mg. wet weight, was 0.22 +/- 0.02, 0.82 +/- 0.09, 0.55 +/- 0.06 and 0.27 +/- 0.06, respectively (mean +/- standard error of mean). Competitive binding experiments with (/sup 125/iodine)-Heat and unlabeled prazosin and clonidine confirmed the selectivity of Heat for alpha 1-adrenergic binding sites. Anatomical dissections have revealed that a major component of the smooth muscle of the bladder base and prostate originates from the ureter, whereas a major component of the smooth muscle of the urethra originates from the bladder. The measured alpha 1-adrenergic receptor densities support these developmental theories.

  20. 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.

  1. Identification of alpha1-adrenergic receptors and their involvement in phosphoinositide hydrolysis in the frog heart.

    PubMed

    Lazou, Antigone; Gaitanaki, Catherine; Vaxevanellis, Spiros; Pehtelidou, Anastasia

    2002-07-01

    The aim of this study was to characterize alpha(1)-adrenergic receptors in frog heart and to examine their related signal transduction pathway. alpha(1)-Adrenergic binding sites were studied in purified heart membranes using the specific alpha(1)-adrenergic antagonist [(3)H]prazosin. Analysis of the binding data indicated one class of binding sites displaying a K(d) of 4.19 +/- 0.56 nM and a B(max) of 14.66 +/- 1.61 fmol/mg original wet weight. Adrenaline, noradrenaline, or phenylephrine, in the presence of propranolol, competed with [(3)H]prazosin binding with a similar potency and a K(i) value of about 10 microM. The kinetics of adrenaline binding was closely related to its biological effect. Adrenaline concentration dependently increased the production of inositol phosphates in the heart in the presence or absence of propranolol. Maximal stimulation was about 8.5-fold, and the half-maximum effective concentration was 30 and 21 microM in the absence and presence of propranolol, respectively. These data clearly show that alpha(1)-adrenergic receptors are coupled to the phosphoinositide hydrolysis in frog heart. To our knowledge, this is the first direct evidence supporting the presence of functional alpha(1)-adrenergic receptors in the frog heart.

  2. Adrenergic receptor control mechanism for growth hormone secretion.

    PubMed

    Blackard, W G; Heidingsfelder, S A

    1968-06-01

    The influence of catecholamines on growth hormone secretion has been difficult to establish previously, possibly because of the suppressive effect of the induced hyperglycemia on growth hormone concentrations. In this study, an adrenergic receptor control mechanism for human growth hormone (HGH) secretion was uncovered by studying the effects of alpha and beta receptor blockade on insulin-induced growth hormone elevations in volunteer subjects. Alpha adrenergic blockade with phentolamine during insulin hypoglycemia, 0.1 U/kg, inhibited growth hormon elevations to 30-50% of values in the same subjects during insulin hypoglycemia without adrenergic blockade. More complete inhibition by phentolamine could not be demonstrated at a lower dose of insulin (0.05 U/kg). Beta adrenergic blockade with propranolol during insulin hypoglycemia significantly enhanced HGH concentrations in paired experiments. The inhibiting effect of alpha adrenergic receptor blockade on HGH concentrations could not be attributed to differences in blood glucose or free fatty acid values; however, more prolonged hypoglycemia and lower plasma free fatty acid values may have been a factor in the greater HGH concentrations observed during beta blockade. In the absence of insulin induced hypoglycemia, neither alpha nor beta adrenergic receptor blockade had a detectable effect on HGH concentrations. Theophylline, an inhibitor of cyclic 3'5'-AMP phosphodiesterase activity, also failed to alter plasma HGH concentrations. These studies demonstrate a stimulatory effect of alpha receptors and a possible inhibitory effect of beta receptors on growth hormone secretion.

  3. Hypoxia sensing through β-adrenergic receptors

    PubMed Central

    Cheong, Hoi I.; Asosingh, Kewal; Stephens, Olivia R.; Queisser, Kimberly A.; Xu, Weiling; Willard, Belinda; Hu, Bo; Dermawan, Josephine Kam Tai; Stark, George R.; Naga Prasad, Sathyamangla V.; Erzurum, Serpil C.

    2016-01-01

    Life-sustaining responses to low oxygen, or hypoxia, depend on signal transduction by HIFs, but the underlying mechanisms by which cells sense hypoxia are not completely understood. Based on prior studies suggesting a link between the β-adrenergic receptor (β-AR) and hypoxia responses, we hypothesized that the β-AR mediates hypoxia sensing and is necessary for HIF-1α accumulation. Beta blocker treatment of mice suppressed hypoxia induction of renal HIF-1α accumulation, erythropoietin production, and erythropoiesis in vivo. Likewise, beta blocker treatment of primary human endothelial cells in vitro decreased hypoxia-mediated HIF-1α accumulation and binding to target genes and the downstream hypoxia-inducible gene expression. In mechanistic studies, cAMP-activated PKA and/or GPCR kinases (GRK), which both participate in β-AR signal transduction, were investigated. Direct activation of cAMP/PKA pathways did not induce HIF-1α accumulation, and inhibition of PKA did not blunt HIF-1α induction by hypoxia. In contrast, pharmacological inhibition of GRK, or expression of a GRK phosphorylation–deficient β-AR mutant in cells, blocked hypoxia-mediated HIF-1α accumulation. Mass spectrometry–based quantitative analyses revealed a hypoxia-mediated β-AR phosphorylation barcode that was different from the classical agonist phosphorylation barcode. These findings indicate that the β-AR is fundamental to the molecular and physiological responses to hypoxia. PMID:28018974

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Effects of subtypes of adrenergic and angiotensinergic antagonists on the water and sodium intake induced by adrenaline injected into the paraventricular nucleus.

    PubMed

    de Arruda Camargo, Luiz Antonio; Saad, Wilson Abrão; Cerri, Paulo Sérgio; de Arruda Camargo, Gabriela Maria Pavan

    2003-12-24

    The present experiments were conducted to investigate the role of the alpha(1A)-, alpha(1B)-, beta(1)-, beta(2)-adrenoceptors, and the effects of losartan and CGP42112A (selective ligands of the AT(1) and AT(2) angiotensin receptors, respectively) on the water and sodium intake elicited by paraventricular nucleus (PVN) injection of adrenaline. Male Holtzman rats with a stainless steel cannula implanted into the PVN were used. The ingestion of water and sodium was determined in separate groups submitted to water deprivation or sodium depletion with the diuretic furosemide (20 mg/rat). 5-Methylurapidil (an alpha(1A)-adrenergic antagonist) and ICI-118,551 (a beta(2)-adrenergic antagonist) injected into the PVN produced a dose-dependent increase, whereas cyclazosin (an alpha(1B)-adrenergic antagonist) and atenolol (a beta(1)-adrenergic antagonist) do not affect the inhibitory effect of water intake induced by adrenaline. On the other hand, the PVN administration of adrenaline increased the sodium intake in a dose-dependent manner. Previous injection of the alpha(1A) and beta(1) antagonists decreased, whereas injection of the alpha(1B) and beta(2) antagonists increased the salt intake induced by adrenaline. In rats with several doses of adrenaline into PVN, the previous administration of losartan increased in a dose-dependent manner the inhibitory effect of adrenaline and decreased the salt intake induced by adrenaline, while PVN CGP42112A was without effect. These results indicate that both appetites are mediated primarily by brain AT(1) receptors. However, the doses of losartan were more effective when combined with the doses of CGP42112A than given alone p<0.05, suggesting that the water and salt intake effects of PVN adrenaline may involve activation of multiple angiotensin II (ANG II) receptors subtypes.

  9. beta-Adrenergic receptor modulation of wound repair.

    PubMed

    Pullar, Christine E; Manabat-Hidalgo, Catherine G; Bolaji, Ranti S; Isseroff, R Rivkah

    2008-08-01

    Adrenergic receptors and their downstream effector molecules are expressed in all cell types in the skin, and it is only recently that functionality of the catecholamine agonist activated signaling in the cutaneous repair process has been revealed. In addition to responding to systemic elevations in catecholamines (as in stress situations) or to pharmacologically administered adrenergic agonists, epidermal keratinocytes themselves can synthesize catecholamine ligands. They also respond to these systemic or self-generated agonists via receptor mediated signaling, resulting in altered migration, and changes in wound re-epithelialization. Endothelial cells, inflammatory cells, dermal fibroblasts, and mesenchymal stem cells, all cells that contribute to the wound repair process, express multiple subtypes of adrenergic receptors and exhibit responses that can be either contribute or impair healing-and occasionally, depending on the species and assay conditions, results can be conflicting. There is still much to be uncovered regarding how this self-contained autocrine and paracrine signaling system contributes to cutaneous wound repair.

  10. Repeated effects of asenapine on adrenergic and cholinergic muscarinic receptors.

    PubMed

    Choi, Yong Kee; Wong, Erik H F; Henry, Brian; Shahid, Mohammed; Tarazi, Frank I

    2010-04-01

    Adrenergic (alpha1 and alpha2) and cholinergic muscarinic (M1-M5) receptor binding in rat forebrain was quantified after 4 wk of twice-daily subcutaneous administration of asenapine or vehicle. Asenapine (0.03, 0.1, and 0.3 mg/kg) produced increases in [3H]prazosin binding to alpha1-adrenergic receptors in the medial prefrontal cortex (mPFC: 30%, 39%, 57%) and dorsolateral frontal cortex (DFC: 27%, 37%, 53%) and increased [3H]RX821002 binding to alpha2-adrenergic receptors in mPFC (36%, 43%, 50%) and DFC (41%, 44%, 52%). Despite showing no appreciable affinity for muscarinic receptors, asenapine produced regionally selective increases in binding of [3H]QNB to M1-M5 receptors in mPFC (26%, 31%, 43%), DFC (27%, 34%, 41%), and hippocampal CA1 (40%, 44%, 42%) and CA3 (25%, 52%, 48%) regions. These regionally selective effects of asenapine on adrenergic and cholinergic muscarinic receptor subtypes may contribute to its beneficial clinical effects in the treatment of schizophrenia and bipolar disorder.

  11. Demonstration of. cap alpha. /sub 2/-adrenergic receptors in rat pancreatic islets using radioligand binding

    SciTech Connect

    Cherksey, B.; Mendelsohn, S.; Zadunaisky, J.; Altszuler, N.

    1982-11-01

    The type of the ..cap alpha..-adrenergic receptors on rat pancreatic islet cells was characterized directly using specific radioligands and displacement agonists and antagonists. Scatchard plots for binding of (/sup 3/H)clonidine (..cap alpha../sub 2/-agonist) revealed a dissociation constant, K/sub d/ of 0.542 +/- 0.1 nM and density of binding sites (B/sub max/) of 50.4 +/- 3.6 fmole/mg protein. Similar values were obtained with (/sup 3/H)dihydroergocryptine (antagonist). The various agonists displaced (/sup 3/H)clonidine with the following order of potency: clonidine > epinephrine approx. = norepinephrine > isoproterenol. Yohimbine, the ..cap alpha../sub 2/-antagonist, was very effective in displacing (/sup 3/H)clonidine, whereas the ..cap alpha../sub 1/-antagonist, prazosin, was much less effective. The data indicate that the ..cap alpha..-adrenergic receptors on rat pancreatic islets are of the ..cap alpha../sub 2/ subtype.

  12. cap alpha. /sub 2/-Adrenergic receptor-mediated sensitization of forskolin-stimulated cyclic AMP production

    SciTech Connect

    Jones, S.B.; Toews, M.L.; Turner, J.T.; Bylund, D.B.

    1987-03-01

    Preincubation of HT29 human colonic adenocarcinoma cells with ..cap alpha../sub 2/-adrenergic agonists resulted in a 10- to 20-fold increase in forskolin-stimulated cyclic AMP production as compared to cells preincubated without agonist. Similar results were obtained using either a (/sup 3/H)adenine prelabeling assay or a cyclic AMP radioimmunoassay to measure cyclic AMP levels. This phenomenon, which is termed sensitization, is ..cap alpha../sub 2/-adrenergic receptor-mediated and rapid in onset and reversal. Yohimbine, an ..cap alpha../sub 2/-adrenergic receptor-selective antagonist, blocked norepinephrine-induced sensitization, whereas prazosin (..cap alpha../sub 1/-adrenergic) and sotalol (..beta..-adrenergic) did not. The time for half-maximal sensitization was 5 min and the half-time for reversal was 10 min. Only a 2-fold sensitization of cyclic AMP production stimulated by vasoactive intestinal peptide was observed, indicating that sensitization is relatively selective for forskolin. Sensitization reflects an increased production of cyclic AMP and not a decreased degradation of cyclic AMP, since incubation with a phosphodiesterase inhibitor and forskolin did not mimic sensitization. Increasing the levels of cyclic AMP during the preincubation had no effect on sensitization, indicating that sensitization is not caused by decreased cyclic AMP levels during the preincubation. This rapid and dramatic sensitization of forskolin-stimulated cyclic AMP production is a previously unreported effect that can be added to the growing list of ..cap alpha../sub 2/-adrenergic responses that are not mediated by a decrease in cyclic AMP.

  13. 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.

  14. Alpha-adrenergic regulation of androgen receptor concentration in the preoptic area of the rat.

    PubMed

    Handa, R J; Resko, J A

    1989-04-03

    We examined the effect of the pharmacological disruption of the catecholaminergic system on the concentration of nuclear androgen receptor, as measured by the in vitro binding of methyltrienolone ([3H]R1881) to salt extracts of anterior pituitary (AP), preoptic area (POA) and medial basal hypothalamus (MBH). Treatment of gonadectomized male and female rats with the dopamine-beta-hydroxylase inhibitor, diethyldithiocarbamate (400 mg/kg b. wt.), 30 min before treatment with dihydrotestosterone (1 mg/animal) produced a decrease in the number of nuclear androgen receptor compared with saline-treated controls (P less than 0.05). This effect was specific for the POA and was not present 15 h after DHT treatment. There was no effect on cytosolic androgen receptor nor was there a drug effect on the apparent dissociation constant (Kd) of [3H]R1881 binding to hypothalamus-preoptic area cytosols. Treatment of intact males and castrated, testosterone-treated males with the alpha 1- and alpha 2-adrenergic antagonists, prazosin (5 mg/kg b. wt.) and yohimbine (2 mg/kg b. wt.), respectively, resulted in a significant decrease in the number of nuclear AR 2 h following drug treatment (P less than 0.05). There was no effect of the beta-adrenergic receptor antagonist propranolol (10 mg/kg b. wt.) when given to intact animals, nor was there an effect of idazoxan (5 mg/kg) when given to testosterone-treated animals. The effects of yohimbine and prazosin were restricted to the POA. None of the drugs competed with the binding of [3H]R1881 for the androgen receptor nor did they alter the Kd of cytosol or nuclear androgen receptor. These data provide evidence for an adrenergic interaction with the POA androgen receptor and suggest a role for catecholamines in modulating androgen sensitivity in the rat brain.

  15. 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.

  16. Muscle plasticity and β₂-adrenergic receptors: adaptive responses of β₂-adrenergic receptor expression to muscle hypertrophy and atrophy.

    PubMed

    Sato, Shogo; Shirato, Ken; Tachiyashiki, Kaoru; Imaizumi, Kazuhiko

    2011-01-01

    We discuss the functional roles of β₂-adrenergic receptors in skeletal muscle hypertrophy and atrophy as well as the adaptive responses of β₂-adrenergic receptor expression to anabolic and catabolic conditions. β₂-Adrenergic receptor stimulation using anabolic drugs increases muscle mass by promoting muscle protein synthesis and/or attenuating protein degradation. These effects are prevented by the downregulation of the receptor. Endurance training improves oxidative performance partly by increasing β₂-adrenergic receptor density in exercise-recruited slow-twitch muscles. However, excessive stimulation of β₂-adrenergic receptors negates their beneficial effects. Although the preventive effects of β₂-adrenergic receptor stimulation on atrophy induced by muscle disuse and catabolic hormones or drugs are observed, these catabolic conditions decrease β₂-adrenergic receptor expression in slow-twitch muscles. These findings present evidence against the use of β₂-adrenergic agonists in therapy for muscle wasting and weakness. Thus, β₂-adrenergic receptors in the skeletal muscles play an important physiological role in the regulation of protein and energy balance.

  17. Modulation of hematopoiesis via alpha 1-adrenergic receptors on bone marrow cells.

    PubMed

    Maestroni, G J; Conti, A

    1994-03-01

    We have recently demonstrated that adrenergic agents can affect hematopoiesis after syngeneic bone marrow transplantation in mice. In particular, chemical sympathectomy by 6-hydroxydopamine (6-OHDA) and/or administration of the alpha 1-adrenergic antagonist prazosin were shown to increase the concentration of blood granulocytes, platelets, and bone marrow colony-forming units-granulocyte/macrophage (CFU-GM), and to induce a granulocytic hyperplasia of the spleen. Here we show that prazosin can also enhance myelopoiesis and platelet formation in normal mice. Furthermore, noradrenaline and the alpha 1-adrenergic agonist methoxamine could directly inhibit the in vitro growth of GM-CFU. The effect of noradrenaline was counteracted by prazosin and by other alpha-adrenergic antagonists such as phentolamine and yohimbine, in the following order of potency: prazosin > phentolamine > yohimbine. In line with these results, we were able to demonstrate that 3H-prazosin binds specifically to both bone marrow cell membranes and intact bone marrow cells. Scatchard analysis of the binding to intact cells revealed the presence of two binding sites. A kd of 0.98 +/- 0.32 nM and a B max of 5 +/- 2.9 fM/2 x 10(6) cells characterized the higher affinity site, while the lower affinity site displayed a kd of 55.9 +/- 8.2 nM and a B max of 44 +/- 7.7 fM/mg protein. These saturation studies, together with competition experiments to evaluate the ability of various adrenergic compounds to displace 3H-prazosin binding, classified the higher affinity site as an alpha 1-adrenergic receptor. The remaining low affinity binding site remains to be characterized. Furthermore, separation of bone marrow cells by counterflow centrifugal elutriation (CCE) showed that the high-affinity binding is due to a lymphoid/stem cell fraction with no blasts and no GM-CFU progenitors. The low-affinity site was apparent on the rotor-off fraction, which was enriched with GM-CFU progenitor cells. These findings

  18. -Adrenergic receptors on rat ventricular myocytes: characteristics and linkage to cAMP metabolism

    SciTech Connect

    Buxton, I.L.O.; Brunton, L.L.

    1986-08-01

    When incubated with purified cardiomyocytes from adult rat ventricle, the 1-antagonist (TH)prazosin binds to a single class of sites with high affinity. Competition for (TH)prazosin binding by the 2-selective antagonist yohimbine and the nonselective -antagonist phentolamine demonstrates that these receptors are of the 1-subtype. In addition, incubation of myocyte membranes with (TH)yohimbine results in no measurable specific binding. Agonist competition for (TH)prazosin binding to membranes prepared from purified myocytes demonstrates the presence of two components of binding: 28% of 1-receptors interact with norepinephrine with high affinity (K/sub D/ = 36 nM), whereas the majority of receptors (72%) have a low affinity for agonist (K/sub D/ = 2.2 M). After addition of 10 M GTP, norepinephrine competes for (TH)prazosin binding to a single class of sites with lower affinity (K/sub D/ = 2.2 M). Incubation of intact myocytes for 2 min with 1 M norepinephrine leads to significantly less cyclic AMP (cAMP) accumulation than stimulation with either norepinephrine plus prazosin or isoproterenol. Likewise, incubation of intact myocytes with 10 W M norepinephrine leads to significantly less activation of cAMP-dependent protein kinase than when myocytes are stimulated by both norepinephrine and the 1-adrenergic antagonist, prazosin or the US -adrenergic agonist, isoproterenol. They conclude that the cardiomyocyte 1 receptor is coupled to a guanine nucleotide-binding protein, that 1-receptors are functionally linked to decreased intracellular cAMP content, and that this change in cellular cAMP is expressed as described activation of cAMP-dependent protein kinase.

  19. The structural basis for agonist and partial agonist action on a β(1)-adrenergic receptor.

    PubMed

    Warne, Tony; Moukhametzianov, Rouslan; Baker, Jillian G; Nehmé, Rony; Edwards, Patricia C; Leslie, Andrew G W; Schertler, Gebhard F X; Tate, Christopher G

    2011-01-13

    β-adrenergic receptors (βARs) are G-protein-coupled receptors (GPCRs) that activate intracellular G proteins upon binding catecholamine agonist ligands such as adrenaline and noradrenaline. Synthetic ligands have been developed that either activate or inhibit βARs for the treatment of asthma, hypertension or cardiac dysfunction. These ligands are classified as either full agonists, partial agonists or antagonists, depending on whether the cellular response is similar to that of the native ligand, reduced or inhibited, respectively. However, the structural basis for these different ligand efficacies is unknown. Here we present four crystal structures of the thermostabilized turkey (Meleagris gallopavo) β(1)-adrenergic receptor (β(1)AR-m23) bound to the full agonists carmoterol and isoprenaline and the partial agonists salbutamol and dobutamine. In each case, agonist binding induces a 1 Å contraction of the catecholamine-binding pocket relative to the antagonist bound receptor. Full agonists can form hydrogen bonds with two conserved serine residues in transmembrane helix 5 (Ser(5.42) and Ser(5.46)), but partial agonists only interact with Ser(5.42) (superscripts refer to Ballesteros-Weinstein numbering). The structures provide an understanding of the pharmacological differences between different ligand classes, illuminating how GPCRs function and providing a solid foundation for the structure-based design of novel ligands with predictable efficacies.

  20. Cellular interactions uncouple beta-adrenergic receptors from adenylate cyclase.

    PubMed

    Ciment, G; de Vellis, J

    1978-11-17

    C6 glioma cells and B104 neuroblastoma cells both possess adenylate cyclase activity, but only C6 cells have beta-adrenergic receptors. However, when cocultured with B104 cells, C6 cells show a marked decrease in their ability to accumulate adenosine 3', 5'-monophosphate upon stimulation with beta receptor agonists. Since both beta receptors and cholera toxin-stimulated adenylate cyclase activities are present in C6/B104 cocultures, we conclude that the beta receptor/adenylate cyclase transduction mechanism in cocultured C6 cells is uncoupled.

  1. Structural analysis of beta-adrenergic and muscarinic cholinergic receptors

    SciTech Connect

    Kerlavage, A.R.; Fraser, C.M.; Venter, J.C.

    1987-05-01

    The authors have recently cloned the gene encoding the human brain beta-adrenergic receptor. Beta-adrenergic and muscarinic cholinergic receptors have also been cloned from other tissues. In order to correlate the primary structures of these receptors with their function, they have undertaken detailed mapping of their functionally important sites. Purified guinea pig lung beta receptor was radioiodinated and digested with trypsin. The resultant peptides were resolved by reverse phase HPLC into nine peaks containing /sup 125/I, corresponding exactly with the predicted number of tyrosine containing peptides in the beta receptor. Hamster lung beta receptor was labeled with (/sup 125/I)-iodocyanopindolol diazarine ((/sup 125/I)CYPD) and partially purified by SDS-PAGE. The (/sup 125/I)CYPD-labeled receptor was extracted from the gel, digested with either trypsin or CNBr and the digests were resolved by reverse phase HPLC. The tryptic digest contained one (/sup 125/I)CYPD-labeled peak and the CNBr digest contained two. Rat brain muscarinic receptor was specifically labeled with (/sup 3/H)-propylbenzilyl-choline mustard ((/sup 3/H)PrBCM) and partially purified by SDS-PABE. The (/sup 3/H)PrBCM-labeled receptor was extracted from the gel and digested with CNBr. The resultant HPLC profile revealed a single (/sup 3/H)PrBCM-labeled peak. These data yield information on the location of functional sites within the primary sequences of these receptors.

  2. alpha(2)-adrenergic receptor-mediated increase in NO production buffers renal medullary vasoconstriction.

    PubMed

    Zou, A P; Cowley, A W

    2000-09-01

    The present study was designed to investigate the role of nitric oxide (NO) in modulating the adrenergic vasoconstrictor response of the renal medullary circulation. In anesthetized rats, intravenous infusion of norepinephrine (NE) at a subpressor dose of 0.1 microgram. kg(-1). min(-1) did not alter renal cortical (CBF) and medullary (MBF) blood flows measured by laser-Doppler flowmetry nor medullary tissue PO(2) (P(m)O(2)) as measured by a polarographic microelectrode. In the presence of the NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME) in the renal medulla, intravenous infusion of NE significantly reduced MBF by 30% and P(m)O(2) by 37%. With the use of an in vivo microdialysis-oxyhemoglobin NO-trapping technique, we found that intravenous infusion of NE increased interstitial NO concentrations by 43% in the renal medulla. NE-stimulated elevations of tissue NO were completely blocked either by renal medullary interstitial infusion of L-NAME or the alpha(2)-antagonist rauwolscine (30 microgram. kg(-1). min(-1)). Concurrently, intavenous infusion of NE resulted in a significant reduction of MBF in the presence of rauwolscine. The alpha(1)-antagonist prazosin (10 microgram. kg(-1). min(-1) renal medullary interstitial infusion) did not reduce the NE-induced increase in NO production, and NE increased MBF in the presence of prazosin. Microdissection and RT-PCR analyses demonstrated that the vasa recta expressed the mRNA of alpha(2B)-adrenergic receptors and that medullary thick ascending limb and collecting duct expressed the mRNA of both alpha(2A)- and alpha(2B)-adrenergic receptors. These subtypes of alpha(2)-adrenergic receptors may mediate NE-induced NO production in the renal medulla. We conclude that the increase in medullary NO production associated with the activation of alpha(2)-adrenergic receptors counteracts the vasoconstrictor effects of NE in the renal medulla and may play an important role in maintaining a constancy of MBF and medullary

  3. Giα and Gβ subunits both define selectivity of G protein activation by α2-adrenergic receptors

    PubMed Central

    Gibson, Scott K.; Gilman, Alfred G.

    2006-01-01

    Previous studies of the specificity of receptor interactions with G protein subunits in living cells have relied on measurements of second messengers or other downstream responses. We have examined the selectivity of interactions between α2-adrenergic receptors (α2R) and various combinations of Giα and Gβ subunit isoforms by measuring changes in FRET between Giα–yellow fluorescent protein and cyan fluorescent protein–Gβ chimeras in HeLa cells. All combinations of Giα1, -2, or -3 with Gβ1, -2, or -4 were activated to some degree by endogenous α2Rs as judged by agonist-dependent decreases in FRET. The degree of G protein activation is determined by the combination of Giα and Gβ subunits rather than by the identity of an individual subunit. RT-PCR analysis and small interfering RNA knockdown of α2R subtypes, followed by quantification of radiolabeled antagonist binding, demonstrated that HeLa cells express α2a- and α2b-adrenergic receptor isoforms in a 2:1 ratio. Increasing receptor number by overexpression of the α2aR subtype minimized the differences among coupling preferences for Giα and Gβ isoforms. The molecular properties of each Giα, Gβ, and α2-adrenergic receptor subtype influence signaling efficiency for the α2-adrenergic receptor-mediated signaling pathway. PMID:16371464

  4. Interdependent Adrenergic Receptor Regulation of Arc and ZIf268 mRNA in Cerebral Cortex

    PubMed Central

    Essali, Norah; Sanders, Jeff

    2015-01-01

    Norepinephrine is a neurotransmitter that signals by stimulating the α1, α2 and β adrenergic receptor (AR). We determined the role of these receptors in regulating the immediate early genes, Activity Regulated Cytoskeleton Associated Protein (Arc) and Zif268 in the rat cerebral cortex. RX821002, an α2 -AR antagonist, produced Arc and Zif268 elevations across cortical layers. Next we examined the effects of delivering RX821002 with an α1- -AR antagonist, prazosin, and a β -AR antagonist, propranolol. RX821002 given with a prazosin and propranolol cocktail, or with each of these antagonists individually, decreased Arc and Zif268 to saline-treated control levels in most cortical layers. Arc and Zif268 levels were also similar to saline-treated control levels when rats were given a prazosin and propranolol cocktail alone, or when each of these antagonists were delivered individually. Taken together, these data reveal that α2 –AR uniquely exert a tonic inibitory regulation of both Arc and Zif268 compared to α1 and β-AR. However, the ability of RX821002 to increase Arc and Zif268 is interdependent with α1 and β –AR signaling. PMID:26655475

  5. Maternal Defense is Modulated by Beta Adrenergic Receptors in Lateral Septum in Mice

    PubMed Central

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

    2011-01-01

    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. 30 μg 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 v. vehicle) without altering other measures. Although the findings were identified in a unique strain of mice that may or may not apply to other strains, 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

  6. Coregulation of calcium channels and beta-adrenergic receptors in cultured chick embryo ventricular cells

    SciTech Connect

    Marsh, J.D. )

    1989-09-01

    To examine mechanisms whereby the abundance of functional Ca channels may be regulated in excitable tissue, Ca channel number was estimated by binding of the dihydropyridine (DHP) antagonist {sup 3}H (+)PN200-110 to monolayers of intact myocytes from chick embryo ventricle. Beta adrenergic receptor properties were studied in cultured myocytes using ({sup 3}H)CGP12177, an antagonist ligand. Physiological correlates for alterations in DHP binding site number included {sup 45}Ca uptake and contractile response to (+)BAYk 8644, a specific L-type Ca channel activator. All binding and physiological determinations were performed in similar intact cell preparations under identical conditions. 4-h exposure to 1 microM isoproterenol reduced cell surface beta-adrenergic receptor number from 44 +/- 3 to 17 +/- 2 fmol/mg (P less than 0.05); DHP binding sites declined in number from 113 +/- 25 to 73 +/- 30 fmol/mg (P less than 0.03). When protein kinase A was activated by a non-receptor-dependent mechanism, DHP binding declined similarly to 68% of control. Exposure to diltiazem, a Ca channel antagonist, for 18-24 h had no effect on number of DHP binding sites. After 4-h isoproterenol exposure, {sup 45}Ca uptake stimulated by BAYk 8644 declined from 3.3 +/- 0.2 nmol/mg to 2.9 +/- 0.3 nmol/mg (P less than 0.01) and BAYk 8644-stimulated increase in amplitude of contraction declined from 168 +/- 7 to 134 +/- 11% (P = 0.02). Thus, elevation of (cAMP) in myocytes is associated with a time-dependent decline in Ca channel abundance as estimated by DHP binding and a decline in physiological responses that are in part dependent on abundance of Ca channels. Binding of a directly acting Ca channel antagonist for 18-24 h does not modulate the number of DHP binding sites.

  7. Alpha-Adrenergic receptors in cerebral microvessels of normotensive and spontaneously hypertensive rats

    SciTech Connect

    Kobayashi, H.; Wada, A.; Izumi, F.; Magnoni, M.S.; Trabucchi, M.

    1985-03-01

    In rat cerebral microvessels, we characterized alpha 1- and alpha 2-adrenergic receptors, using (/sup 3/H)prazosin and (/sup 3/H)-p-amino-clonidine as radioligands. (/sup 3/H)Prazosin binding to the cerebral microvessels was saturable and of high affinity (dissociation constant of 78 pM), with a maximum binding of 48 fmol/mg protein. (/sup 3/H)Prazosin binding reached equilibrium within 15 minutes and was dissociated by the addition of 10 microM phentolamine. The inhibitory effects of isomers of norepinephrine and epinephrine on the binding showed that l-isomers were over 10 times more potent than d-isomers. (/sup 3/H)-p-Amino-clonidine binding to the cerebral microvessels was saturable and of high affinity (K/sub D/ . 0.61 nM) with a B/sub max/ of 73 fmol/mg protein. The binding reached equilibrium within 30 minutes, and was dissociated by the addition of 100 microM l-norepinephrine. l-Isomers of norepinephrine and epinephrine were over 10 times more potent than d-isomers in displacing the binding. Thus, both (/sup 3/H)prazosin and (/sup 3/H)-p-amino-clonidine bindings to the cerebral microvessels were characterized by saturability, high affinity, reversibility, and stereo-specificity. Furthermore, the specificity of both binding sites was pharmacologically evaluated by the inhibitory effects of various adrenergic agonists and antagonists on the bindings. These data indicate the existence of alpha-adrenergic receptors in the cerebral microvessels and are consistent with the hypothesis that the cerebral microcirculation is regulated by adrenergic innervation. Furthermore, the receptors were measured in cerebral microvessels of spontaneously hypertensive rats and Wistar-Kyoto controls.

  8. 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

  9. Regulation of cyclic AMP formation in cultures of human foetal astrocytes by beta 2-adrenergic and adenosine receptors.

    PubMed

    Woods, M D; Freshney, R I; Ball, S G; Vaughan, P F

    1989-09-01

    Two cell cultures, NEP2 and NEM2, isolated from human foetal brain have been maintained through several passages and found to express some properties of astrocytes. Both cell cultures contain adenylate cyclase stimulated by catecholamines with a potency order of isoprenaline greater than adrenaline greater than salbutamol much greater than noradrenaline, which is consistent with the presence of beta 2-adrenergic receptors. This study reports that the beta 2-adrenergic-selective antagonist ICI 118,551 is approximately 1,000 times more potent at inhibiting isoprenaline stimulation of cyclic AMP (cAMP) formation in both NEP2 and NEM2 than the beta 1-adrenergic-selective antagonist practolol. This observation confirms the presence of beta 2-adrenergic receptors in these cell cultures. The formation of cAMP in NEP2 is also stimulated by 5'-(N-ethylcarboxamido)adenosine (NECA) more potently than by either adenosine or N6-(L-phenylisopropyl)adenosine (L-PIA), which suggests that this foetal astrocyte expresses adenosine A2 receptors. Furthermore, L-PIA and NECA inhibit isoprenaline stimulation of cAMP formation, a result suggesting the presence of adenosine A1 receptors on NEP2. The presence of A1 receptors is confirmed by the observation that the A1-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine reverses the inhibition of isoprenaline stimulation of cAMP formation by L-PIA and NECA. Additional evidence that NEP2 expresses adenosine receptors linked to the adenylate cyclase-inhibitory GTP-binding protein is provided by the finding that pretreatment of these cells with pertussis toxin reverses the adenosine inhibition of cAMP formation stimulated by either isoprenaline or forskolin.

  10. 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.

  11. Effect of adrenergic agonists and antagonists on alanine amino transferase, fructose-1:6-bisphosphatase and glucose production in hepatocytes.

    PubMed

    Begum, N A; Datta, A G

    1992-08-18

    Using rat hepatocytes we confirmed our previous results that glucagon and beta-adrenergic agonists increased the enzyme activity of alanine aminotransferase (AAT) and propranolol abolished their effects. Only the enzyme activity was measured and other parameters like quantity of the enzyme or activation due to modification were not looked for. As in perfusion experiment phenylephrine and phenoxybenzamine (alpha-agonist and alpha-antagonist respectively) also alpha-antagonist respectively) also increased the AAT activity in isolated rat hepatocytes and propranolol reversed these effects. The additive effect of glucagon and phenoxybenzamine on AAT was also persistent in hepatocyte system. Fructose-1:6-bisphosphatase (Fru-P2-ase), another key enzyme in gluconeogenic pathway, was elevated by glucagon and other beta-adrenergic agonists both in liver perfusion and isolated hepatocyte experiments and was brought back to the normal level by propranolol. In this case also only the enzyme activity was measured and no other parameters were looked for. Unlike AAT this enzyme was not stimulated by phenylephrine or phenoxybenzamine. But AAT and Fru-P2-ase activities were increased significantly by adenylate cyclase activators like fluoride or forskolin. Thus, it appears that the regulation of fru-P2-ase by glucagon is purely a b-receptor mediated process whereas AAT activation shows a mixed type of regulation where some well known alpha-agonist and antagonists are behaving as beta-agonists. Results further indicate the presence of phosphodiesterase in hepatocyte membrane which was stimulated by glucagon and brought back to the normal level by propranolol. The different adrenergic compounds stated above, not only modified the activity of the above two enzymes but also stimulated glucose production by hepatocytes from alanine which was in turn abolished by propranolol as well as amino oxyacetate (AOA), a highly specified inhibitor of AAT. This confirm the participation of AAT in

  12. 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

  13. Beta 2-adrenergic receptors are colocalized and coregulated with whisker barrels in rat somatosensory cortex

    SciTech Connect

    Vos, P.; Kaufmann, D.; Hand, P.J.; Wolfe, B.B. )

    1990-07-01

    Autoradiography has been used to visualize independently the subtypes of beta-adrenergic receptors in rat somatosensory cortex. Beta 2-adrenergic receptors, but not beta 1-adrenergic receptors colocalize with whisker barrels in this tissue. Thus, each whisker sends a specific multisynaptic pathway to the somatosensory cortex that can be histochemically visualized and only one subtype of beta-adrenergic receptor is specifically associated with this cortical representation. Additionally, neonatal lesion of any or all of the whisker follicles results in loss of the corresponding barrel(s) as shown by histochemical markers. This loss is paralleled by a similar loss in the organization of beta 2-adrenergic receptors in the somatosensory cortex. Other results indicate that these beta 2-adrenergic receptors are not involved in moment-to-moment signal transmission in this pathway and, additionally, are not involved in a gross way in the development of whisker-barrel array.

  14. Effect of adrenergic receptor blockade on cortisol and GH response to insulin-induced hypoglycemia in man.

    PubMed

    Jezová-Repceková, D; Klimes, I; Jurcovicová, J; Vigas, M

    1979-02-01

    The effect of several drugs presumably influencing central catecholaminergic receptors on plasma cortisol and GH response to insulin-induced hypoglycemia was studied in healthy adult males. The intravenous infusion of alpha-adrenergic blocking agents tolazoline or phentolamine supressed plasma cortisol and GH response to insulin-induced hypoglycemia. After an infusion of beta-adrenergic antagonist propranolol both hypoglycemia and rise in plasma cortisol and GH were prolonged. Finally, the administration of dopaminergic blocker pimozide failed to affect the plasma cortisol response, but slightly suppressed the enhancement of GH release during hypoglycemia. Caution is recommended before making suggestions about neuroendocrine regulations from the data obtained after systemic administration of drugs. Nevertheless, it may be concluded that the hypothesis on the inhibitory role of the central alpha-adrenergic system on ACTH secretion suggested in rats and dogs was not confirmed by our results obtained in man.

  15. β2–Adrenergic Receptor Antagonism Attenuates CNV Through Inhibition of VEGF and IL-6 Expression

    PubMed Central

    Lavine, Jeremy A.; Farnoodian, Mitra; Wang, Shoujian; Darjatmoko, Soesiawati R.; Wright, Lynda S.; Gamm, David M.; Ip, Michael S.; Sorenson, Christine M.; Sheibani, Nader

    2017-01-01

    Purpose The role of β–adrenergic receptor (AR) signaling in neovascular ocular diseases has recently emerged. We have previously reported that intraperitoneal propranolol inhibits choroidal neovascularization (CNV) in vivo and β2-AR blockade reduces vascular endothelial growth factor (VEGF) expression in mouse retinal pigment epithelium and choroidal endothelial cells in culture. Here we tested the hypothesis that the β2-AR regulates CNV through modulation of VEGF and inflammatory cytokine expression. Methods Mice were subjected to laser burns, inducing CNV, and were treated with an intravitreal β2-AR antagonist. After 3 and 5 days, total eye interleukin-6 (IL-6) and VEGF protein levels were measured, respectively. After 14 days, CNV was measured on choroidal–scleral flatmounts. The effects of β-AR signaling on VEGF and IL-6 expression were investigated in various mouse retinal and human RPE cells by using specific β-AR agonists and antagonists. Results β2–Adrenergic receptor signaling increased Vegf mRNA expression by approximately 3- to 4-fold in mouse retinal microglia and pericytes in culture. β2–Adrenergic receptor signaling upregulated IL-6 mRNA expression between 10- and 60-fold in mouse retinal microglia, pericytes, RPE, and choroidal endothelial cells in culture. Intravitreal injection of β2-AR antagonist ICI 118,551 reduced CNV by 35% and decreased IL-6 protein levels by approximately 50%. In primary human RPE cells, β2-AR activation also stimulated VEGF and IL-6 mRNA expression by 2- and 10-fold, respectively. Conclusions Anti-VEGF therapy for CNV is highly effective; however, some patients are resistant to therapy while others undergo repeated, frequent treatments. β2–Adrenergic receptor signaling is a potential therapeutic target because of its angiogenic and inflammatory properties. PMID:28114591

  16. Involvement of Cholinergic and Adrenergic Receptors in Pathogenesis and Inflammatory Response Induced by Alpha-Neurotoxin Bot III of Scorpion Venom.

    PubMed

    Nakib, Imene; Martin-Eauclaire, Marie-France; Laraba-Djebari, Fatima

    2016-10-01

    Bot III neurotoxin is the most lethal α neurotoxin purified from Buthus occitanus tunetanus scorpion venom. This toxin binds to the voltage-gated sodium channel of excitable cells and blocks its inactivation, inducing an increased release of neurotransmitters (acetylcholine and catecholamines). This study aims to elucidate the involvement of cholinergic and adrenergic receptors in pathogenesis and inflammatory response triggered by this toxin. Injection of Bot III to animals induces an increase of peroxidase activities, an imbalance of oxidative status, tissue damages in lung parenchyma, and myocardium correlated with metabolic disorders. The pretreatment with nicotine (nicotinic receptor agonist) or atropine (muscarinic receptor antagonist) protected the animals from almost all disorders caused by Bot III toxin, especially the immunological alterations. Bisoprolol administration (selective β1 adrenergic receptor antagonist) was also efficient in the protection of animals, mainly on tissue damage. Propranolol (non-selective adrenergic receptor antagonist) showed less effect. These results suggest that both cholinergic and adrenergic receptors are activated in the cardiopulmonary manifestations induced by Bot III. Indeed, the muscarinic receptor appears to be more involved than the nicotinic one, and the β1 adrenergic receptor seems to dominate the β2 receptor. These results showed also that the activation of nicotinic receptor leads to a significant protection of animals against Bot III toxin effect. These findings supply a supplementary data leading to better understanding of the mechanism triggered by scorpionic neurotoxins and suggest the use of drugs targeting these receptors, especially the nicotinic one in order to counteract the inflammatory response observed in scorpion envenomation.

  17. NMDA receptor antagonists extend the sensitive period for imprinting.

    PubMed

    Parsons, C H; Rogers, L J

    2000-03-01

    Filial imprinting in the domestic chick occurs during a sensitive period of development. The exact timing of this period can vary according to the methods used to measure imprinting. Using our imprinting paradigm, we have shown that normal, dark-reared chicks lose the ability to imprint after the second day post-hatching. Further, we reported that chicks treated 10 h after hatching with a mixture of the noncompetitive NMDA receptor antagonist ketamine (55 mg/kg) and the alpha(2)-adrenergic receptor agonist xylazine (6 mg/kg) were able to imprint on day 8 after hatching, whereas controls treated with saline did not imprint. We now show that the effect of the ketamine-xylazine mixture can be mimicked by treating chicks with ketamine alone or with another noncompetitive NMDA receptor antagonist, MK-801 (5 mg/kg). Treating chicks with a single dose of ketamine (55 mg/kg) or with a single dose of xylazine (6 mg/kg) failed to produce the effect on the sensitive period. However, prolonging the action of ketamine by treating chicks with two doses of ketamine (at 10 and 12 h after hatching) did allow imprinting on day 8. In contrast, prolonging the action of xylazine had no effect on the sensitive period for imprinting. Chicks treated with MK-801 were also able to imprint on day 8. Thus, we have evidence that the NMDA receptor system is involved in the mechanisms that control the sensitive period for imprinting.

  18. 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.

  19. 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.

  20. Role of alpha 1- and alpha 2-adrenergic receptors in the growth hormone and prolactin response to insulin-induced hypoglycemia in man.

    PubMed

    Tatár, P; Vigas, M

    1984-09-01

    The effects of intravenous infusion of the nonselective alpha-adrenergic antagonist phentolamine or of the selective alpha 2-adrenergic antagonist yohimbine on growth hormone (GH), prolactin (PRL) and cortisol secretion during insulin-induced hypoglycemia were studied in 11 healthy young men. The GH response was blunted following each antagonist used, PRL secretion was higher after yohimbine and diminished after phentolamine when compared to controls. The plasma cortisol response was not influenced by either compound. In another series of experiments no effect of an oral administration of prazosin, a selective alpha 1-adrenergic antagonist, on the secretion of GH, PRL and cortisol was found in any of 7 subjects. Prazosin inhibited blood pressure increase during hypoglycemia and induced slight drowsiness and fatigue in the subjects. It is concluded that in man alpha-adrenergic stimulation of GH secretion during hypoglycemia is transmitted via alpha 2-receptors, PRL secretion is mediated via alpha 1-receptors, whereas inhibition of PRL release is mediated via alpha 2-receptors. In this experiment no effect of alpha 1- or alpha 2-blockade on cortisol response to hypoglycemia was seen.

  1. Effect of beta-adrenergic antagonists on bioluminescence control in three species of brittlestars (Echinodermata: Ophiuroidea).

    PubMed

    Dupont, S; Mallefet, J; Vanderlinden, C

    2004-05-01

    The role of adrenaline in the nervous control of bioluminescence in three brittlestar species, Amphiura filiformis, Amphipholis squamata, and Ophiopsila aranea, was assessed by testing two different beta-adrenergic antagonists (propranolol and labetalol) over a wide concentration range (10(-10)-10(-3)M). We compared the effects of analogues (active vs. inactive) of the same substance (L- and D-enantiomers of propranolol). Propranolol presented both specific and nonspecific effects: (i) nonspecific effects were observed at the higher concentrations tested (10(-4) and 10(-3)M) in all three species; (ii) specific effects were detected only at the lower concentrations tested (10(-6)-10(-5)M). In A. squamata, the involvement of adrenaline in the nervous control of luminescence is supported by propranolol and labetolol specific inhibition. The neuropharmacological implications of nonspecific effects, the involvement of adrenaline and the interspecific differences in the brittlestar nervous control of bioluminescence are discussed.

  2. Enzyme induction and β-adrenergic receptor blocking drugs

    PubMed Central

    Branch, R. A.; Herman, R. J.

    1984-01-01

    1 All β-adrenergic receptor blockers that require metabolism prior to elimination are potentially subject to drug interactions due to enzyme induction. However, data is only available in man for propranolol, metoprolol and alprenolol. 2 Cross-sectional population studies suggest that environmental factors, such as smoking in the young, are able to influence the oral clearance of propranolol. 3 Long-term studies comparing within-subject clearances of metoprolol, alprenolol and propranolol before and after rifampicin and pentobarbitone, indicate that oral clearance is increased by 50%-500%. 4 Inducing agents can influence intrinsic clearance, liver blood flow, and protein binding in addition to drug metabolising ability, indicating that changes in pharmacokinetic disposition may be complex. 5 Enzyme induction exhibits both dose and time dependency relationships. 6 The maximal extent of enzyme induction is similar between subjects. The range of intersubject variation in drug metabolism is similar before and after induction. 7 The reduction in steady-state β-adrenergic receptor drug concentration following enzyme induction is sufficiently large that an altered pharmacodynamic response would be expected if no dosage modification is made. PMID:6146342

  3. 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.

  4. Effect Of α2-Adrenergic Agonists And Antagonists On Cytokine Release From Human Lung Macrophages Cultured In Vitro

    PubMed Central

    Piazza, O.; Staiano, R.I.; De Robertis, E.; Conti, G.; Di Crescenzo, V.; Loffredo, S.; Marone, G.; Marinosci, G. Zito; Cataldi, M. M.

    2016-01-01

    The most trusted hypothesis to explain how α2-adrenergic agonists may preserve pulmonary functions in critically ill patients is that they directly act on macrophages by interfering with an autocrine/paracrine adrenergic system that controls cytokine release through locally synthetized noradrenaline and α1- and α2-adrenoreceptors. We tested this hypothesis in primary cultures of resident macrophages from human lung (HLMs). HLMs were isolated by centrifugation on percoll gradients from macroscopically healthy human lung tissue obtained from four different patients at the time of lung resection for cancer. HLMs from these patients showed a significant expression of α2A, α2B and α2C adrenoreceptors both at the mRNA and at the protein level. To evaluate whether α2 adrenoreceptors controlled cytokine release from HMLs, we measured IL-6, IL-8 and TNF-α concentrations in the culture medium in basal conditions and after preincubation with several α2-adrenergic agonists or antagonists. Neither the pretreatment with the α2-adrenergic agonists clonidine, medetomidine or dexdemetomidine or with the α2-adrenergic antagonist yohimbine caused significant changes in the response of any of these cytokines to LPS. These results show that, different from what reported in rodents, clonidine and dexdemetomidine do not directly suppress cytokine release from human pulmonary macrophages. This suggests that alternative mechanisms such as effects on immune cells activation or the modulation of autonomic neurotransmission could be responsible for the beneficial effects of these drugs on lung function in critical patients. PMID:27896229

  5. Post-Stress Combined Administration of Beta-Receptor and Glucocorticoid Antagonists as a Novel Preventive Treatment in an Animal Model of PTSD

    DTIC Science & Technology

    2010-05-01

    promising, but mixed results were obtained with the acute drug interventions. Propranolol had no effect, and mifepristone had only a modest effect on...stress, PTSD, open field test, social interaction test, fear conditioning, extinction, beta-adrenergic receptors, glucocorticoids, propranolol ...study, social interaction was unaffected (B). Combined treatment with the β-receptor antagonist, propranolol (10 mg/kg) and glucocorticoid-receptor

  6. Characterization of a β-adrenergic-like octopamine receptor from the rice stem borer (Chilo suppressalis).

    PubMed

    Wu, Shun-Fan; Yao, Yao; Huang, Jia; Ye, Gong-Yin

    2012-08-01

    Octopamine, the invertebrate counterpart of adrenaline and noradrenaline, plays a key role in regulation of many physiological and behavioral processes in insects. It modulates these functions through binding to specific octopamine receptors, which are typical rhodopsin-like G-protein coupled receptors. A cDNA encoding a seven-transmembrane receptor was cloned from the nerve cord of the rice stem borer, Chilo suppressalis, viz. CsOA2B2, which shares high sequence similarity to CG6989, a Drosophila β-adrenergic-like octopamine receptor (DmOctβ2R). We generated an HEK-293 cell line that stably expresses CsOA2B2 in order to examine the functional and pharmacological properties of this receptor. Activation of CsOA2B2 by octopamine increased the production of cAMP in a dose-dependent manner (EC(50)=2.33 nmol l(-1)), with a maximum response at 100 nmol l(-1). Tyramine also activated the receptor but with much less potency than octopamine. Dopamine and serotonin had marginal effects on cAMP production. Using a series of known agonists and antagonists for octopamine receptors, we observed a rather unique pharmacological profile for CsOA2B2 through measurements of cAMP. The rank order of potency of the agonists was naphazoline > clonidine. The activated effect of octopamine is abolished by co-incubation with phentolamine, mianserin or chlorpromazine. Using in vivo pharmacology, CsOA2B2 antagonists mianserin and phentolamine impaired the motor ability of individual rice stem borers. The results of the present study are important for a better functional understanding of this receptor as well as for practical applications in the development of environmentally sustainable pesticides.

  7. Solubilization of a guanyl nucleotide-sensitive alpha/sub 1/ adrenergic receptor from liver membranes

    SciTech Connect

    Harris, S.I.; Moss, J.

    1987-05-01

    Rat liver membranes incubated with norepinephrine before solubilization with digitonin yielded a soluble hormone-receptor complex from which the release of tightly bound norepinephrine was facilitated by guanyl nucleotides. Binding of the alpha/sub 1/-adrenergic receptor antagonist, (/sup 3/H)-prazosin, to the soluble preparation was utilized as a gauge of guanyl nucleotide-induced release of receptor-bound agonist. The following potency series was obtained with regard to the ability of guanyl nucleotides to facilitate (/sup 3/H)-prazosin binding to the solubilized preparation: guanosine 5'-0-(3-thiotriphosphate)(K/sub 1/2/ = 2.5 nM), guanylyl-imidodiphosphate (K/sub 1/2/ = 10 nM), guanosine triphosphate (K/sub 1/2/ = 34 nM) and adenylyl-imidodiphosphate (K/sub 1/2/ > 1 mM). In the presence of guanylyl-imidodiphosphate (0.4 mM), the receptor population displayed monotonic binding parameters with a K/sub d/ for (/sup 3/H)-prazosin of 1.16 nM by Scatchard analysis. Competition curves against (/sup 3/H)-prazosin with the antagonists phentolamine and yohimbine revealed respective K/sub i/'s of .089 ..mu..M and 1.8 ..mu..M; curves with the agonists norepinephrine and isoproterenol yielded respective K/sub i/'s of 6.2..mu..M and 360 ..mu..M. Competition curves performed in the absence of guanyl nucleotide were complex demonstrating an apparent increase in affinity for agonists and an apparent decrease in affinity for antagonists. These curve shifts are consistent with the conversion of receptor to and from the guanyl nucleotide-sensitive state as a function of competing ligand concentration.

  8. Beta-Adrenergic Receptor 1 Selective Antagonism Inhibits Norepinephrine-Mediated TNF-Alpha Downregulation in Experimental Liver Cirrhosis

    PubMed Central

    Zapater, Pedro; Gómez-Hurtado, Isabel; Peiró, Gloria; González-Navajas, José Manuel; García, Irma; Giménez, Paula; Moratalla, Alba; Such, José; Francés, Rubén

    2012-01-01

    Background Bacterial translocation is a frequent event in cirrhosis leading to an increased inflammatory response. Splanchnic adrenergic system hyperactivation has been related with increased bacterial translocation. We aim at evaluating the interacting mechanism between hepatic norepinephrine and inflammation during liver damage in the presence of bacterial-DNA. Animals and Methods Forty-six mice were included in a 16-week protocol of CCl4-induced cirrhosis. Laparotomies were performed at weeks 6, 10, 13 and 16. A second set of forty mice injected with a single intraperitoneal dose of CCl4 was treated with saline, 6-hydroxidopamine, Nebivolol or Butoxamine. After 5 days, mice received E. coli-DNA intraperitoneally. Laparotomies were performed 24 hours later. Liver bacterial-DNA, norepinephrine, TNF-alpha, IL-6 and beta-adrenergic receptor levels were measured. Results Bacterial-DNA translocation was more frequent in CCl4-treated animals compared with controls, and increased as fibrosis progressed. Liver norepinephrine and pro-inflammatory cytokines were significantly higher in mice with vs without bacterial-DNA (319.7±120.6 vs 120.7±68.6 pg/g for norepinephrine, 38.4±6.1 vs 29.7±4.2 pg/g for TNF-alpha, 41.8±7.4 vs 28.7±4.3 pg/g for IL-6). Only beta-adrenergic receptor-1 was significantly increased in treated vs control animals (34.6±7.3 vs 12.5±5.3, p = 0.01) and correlated with TNF-alpha, IL-6 and norepinephrine hepatic levels in animals with bacterial-DNA. In the second set of mice, cytokine levels were increased in 6-hydroxidopamine and Nebivolol (beta-adrenergic receptor-1 antagonist) treated mice compared with saline. Butoxamine (beta-adrenergic receptor-2 antagonist) didn’t inhibit liver norepinephrine modulation of pro-inflammatory cytokines. Conclusions Beta-adrenergic receptor-1 mediates liver norepinephrine modulation of the pro-inflammatory response in CCl4-treated mice with bacterial-DNA. PMID:22916250

  9. Roles of β-adrenergic receptors in Alzheimer's disease: implications for novel therapeutics.

    PubMed

    Yu, Jin-Tai; Wang, Nai-Dong; Ma, Teng; Jiang, Hong; Guan, Jun; Tan, Lan

    2011-02-01

    Alzheimer's disease (AD), the most common cause of age-related dementia, is a progressive neurodegenerative disorder with an enormous unmet medical need. In recent years, several unexpected longitudinal and cross-sectional epidemiological studies reveal that beta-blockers treatment reduces the prevalence of AD in patients suffering from hypertension. Now, a newly population-based study of individuals with incident AD demonstrates that beta-blockers are also associated with delay of functional decline. Furthermore, accumulated convincing evidences from cell culture experiments and animal studies have also suggested that β-adrenergic receptors (β-ARs) may involve in the AD pathogenesis through effects on amyloid-β (Aβ) production or inflammation. This review explores clinical and experimental studies that might help to explain the roles of β-ARs in the AD pathogenesis and the potential underlying mechanisms and whether treatment with β-ARs antagonists provides a new therapeutic option for AD.

  10. The β3-adrenergic receptor is dispensable for browning of adipose tissues.

    PubMed

    de Jong, Jasper M A; Wouters, René T F; Boulet, Nathalie; Cannon, Barbara; Nedergaard, Jan; Petrovic, Natasa

    2017-02-21

    Brown and brite/beige adipocytes are attractive therapeutic targets to treat metabolic diseases. To maximally utilize their functional potential, further understanding is required about their identities and their functional differences. Recent studies with β3-adrenergic receptor knockout mice reported that brite/beige adipocytes, but not classical brown adipocytes, require the β3-adrenergic receptor for cold-induced transcriptional activation of thermogenic genes. We aimed to further characterize this requirement of the β3-adrenergic receptor as a functional distinction between classical brown and brite/beige adipocytes. However, when comparing wild-type and β3-adrenergic receptor knockout mice, we observed no differences in cold-induced thermogenic gene expression (Ucp1, Pgc1a, Dio2 and Cidea) in brown or white (brite/beige) adipose tissues. Irrespective of the duration of the cold exposure or the sex of the mice, we observed no effect of the absence of the β3-adrenergic receptor. Experiments with the β3-adrenergic receptor agonist CL-316,243 verified the functional absence of β3-adrenergic signaling in these knockout mice. The β3-adrenergic receptor knockout model in the present study was maintained on a FVB/N background, whereas earlier reports used C57BL/6 and 129Sv mice. Thus, our data imply background-dependent differences in adrenergic signaling mechanisms in response to cold exposure. Nonetheless, the present data indicate that the β3-adrenergic receptor is dispensable for cold-induced transcriptional activation in both classical brown and, as opposed to earlier studies, brite/beige cells. This should be taken into account in the increasing number of studies on the induction of browning and their extrapolation to human physiology.

  11. Beta-Adrenergic Receptor Blockers in Hypertension: Alive and Well.

    PubMed

    Frishman, William H

    2016-10-27

    βeta-Adrenergic receptor blockers (β-blockers) are an appropriate treatment for patients having systemic hypertension (HTN) who have concomitant ischemic heart disease (IHD), heart failure, obstructive cardiomyopathy, aortic dissection or certain cardiac arrhythmias. β-blockers can be used in combination with other antiHTN drugs to achieve maximal blood pressure control. Labetalol can be used in HTN emergencies and urgencies. β-blockers may be useful in HTN patients having a hyperkinetic circulation (palpitations, tachycardia, HTN, and anxiety), migraine headache, and essential tremor. β-blockers are highly heterogeneous with respect to various pharmacologic properties: degree of intrinsic sympathomimetic activity , membrane stabilizing activity , β1 selectivity, α1-adrenergic blocking effects, tissue solubility, routes of systemic elimination, potencies and duration of action, and specific properties may be important in the selection of a drug for clinical use. β-blocker usage to reduce perioperative myocardial ischemia and cardiovascular (CV) complications may not benefit as many patients as was once hoped, and may actually cause harm in some individuals. Currently the best evidence supports perioperative β-blocker use in two patient groups: patients undergoing vascular surgery with known IHD or multiple risk factors for it, and for those patients already receiving β-blockers for known CV conditions.

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

    PubMed

    von Homeyer, Peter; Schwinn, Debra A

    2011-12-01

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

  13. Characterization of beta-adrenergic receptors through the replicative life span of IMR-90 cells

    SciTech Connect

    Scarpace, P.J.

    1987-01-01

    Beta-adrenergic receptor number and receptor affinity for isoproterenol were assessed at various in vitro ages of the human diploid fibroblast cell line IMR-90. From population doubling level (PDL) 33 to 44, there was a positive correlation between beta-adrenergic receptor density and PDL. Beta-adrenergic receptors, assessed by Scatchard analysis of (/sup 125/I)-iodocyanopindolol (ICYP) binding, increased from 15 fmol/mg protein at PDL 33 to 36 fmol/mg protein at PDL 44. In contrast, from PDL 44 to 59, there was a negative correlation between beta-adrenergic receptor density and PDL. Receptor density declined to 12 fmol/mg protein at PDL 59. When the density of beta-adrenergic receptors was expressed as receptor per cell, the findings were similar. Receptor agonist affinity for isoproterenol was determined from Hill plots of (/sup 125/I)-ICYP competition with isoproterenol. There was no change in the dissociation constant for isoproterenol with in vitro age. In humans, serum norepinephrine concentrations increase with age. This increase in serum norepinephrine may be partially responsible for the decreased beta-adrenergic receptor-agonist affinity observed with age in human lymphocytes and rat heart and lung. The present findings are consistent with the hypothesis that the decreases in receptor agonist affinity in rat and man with age are secondary to increases in catecholamine concentrations.

  14. Pharmacological analysis of calcium antagonist receptors

    SciTech Connect

    Reynolds, I.J.

    1987-01-01

    This work focuses on two aspects of the action of calcium antagonist drugs, namely, the interaction of drugs with receptors for verapamil-like calcium antagonists, and the interactions of drugs with voltage-sensitive calcium fluxes in rat brain synaptosomes. From binding studies I have found that the ligand of choice for labeling the verapamil receptor is (-)(/sup 3/H)desmethoxy-verapamil. This drug labels potently, reversibly and stereoselectively two receptors in membranes prepared from rat brain and rabbit skeletal muscle tissues. In equilibrium studies dihydropyridine calcium antagonists interact in a non-competitive fashion, while many non-DHPs are apparently competitive. In-depth kinetic studies in skeletal muscle membranes indicate that the two receptors are linked in a negative heterotropic fashion, and that low-affinity binding of (-) (/sup 3/H)desmethoxy-verapamil may be to the diltiazem receptor. However, these studies were not able to distinguish between the hypothesis that diltiazem binds to spatially separate, allosterically coupled receptors, and the hypothesis that diltiazem binds to a subsite of the verapamil receptor.

  15. Drug-disease interactions: reduced β-adrenergic and potassium channel antagonist activities of sotalol in the presence of acute and chronic inflammatory conditions in the rat

    PubMed Central

    Kulmatycki, Kenneth M; Abouchehade, Kassem; Sattari, Saeed; Jamali, Fakhreddin

    2001-01-01

    Inflammation may influence response to pharmacotherapy. We investigated the effect of inflammation on response to sotalol, a β-adrenergic receptor and potassium channel antagonist. Racemic sotalol (40 mg kg−1) was administered to healthy, acutely (interferonα 2a-induced) and chronically (Mycobacterium butyricum-induced adjuvant arthritis) inflamed male Sprague-Dawley rats (n=4 – 6/group). Another group of interferon-treated rats received 3 mg kg−1 of anti-TNF antibody infliximab. Electrocardiogram (ECG) recorded and plasma sotalol concentration monitored for 6 h. The study was repeated in acutely inflamed rats following administration of stereochemically pure individual sotalol enantiomers [40 mg kg−1 S (potassium channel blocker) or 20 mg kg−1 R (β-adrenergic/potassium channel blocker)]. Chronic arthritis was readily evident. Acute arthritis was associated with elevated segmented neutrophils and increased plasma nitrite and tumour necrosis factor (TNF) concentrations. Sotalol affected ECG in all rats. In both inflamed groups, however, response to sotalol in prolongation of QT interval (potassium channel sensitivity) was reduced. The effect of PR interval (β-adrenergic activity) was also reduced following administration of the racemate and R-enantiomer. No significant differences in pharmacokinetics were observed between control and inflamed rats. Infliximab reduced nitrite and TNF concentrations and reversed the effect of acute inflammation on both PR and QT intervals. The reduced electrocardiographic responses to sotalol is likely due to the influence of inflammation on the action of the drug on both β-adrenergic and potassium channel receptors secondary to over-expression of pro-inflammatory cytokines and/or nitric oxide. Our observation may have therapeutic consequences in all conditions where inflammatory mediators are increased. PMID:11350865

  16. MOOD STATES, SYMPATHETIC ACTIVITY, AND IN VIVO β-ADRENERGIC RECEPTOR FUNCTION IN A NORMAL POPULATION

    PubMed Central

    Yu, Bum-Hee; Kang, Eun-Ho; Ziegler, Michael G.; Mills, Paul J.; Dimsdale, Joel E.

    2009-01-01

    The purpose of this study was to examine the relationship between mood states and β-adrenergic receptor function in a normal population. We also examined if sympathetic nervous system activity is related to mood states or β-adrenergic receptor function. Sixty-two participants aged 25–50 years were enrolled in this study. Mood states were assessed using the Profile of Mood States (POMS). β-adrenergic receptor function was determined using the chronotropic 25 dose isoproterenol infusion test. Level of sympathetic nervous system activity was estimated from 24-hr urine norepinephrine excretion. Higher tension-anxiety, depression-dejection, and anger-hostility were related to decreased β-adrenergic receptor sensitivity (i.e., higher chronotropic 25 dose values), but tension-anxiety was the only remaining independent predictor of β-adrenergic receptor function after controlling for age, gender, ethnicity, and body mass index (BMI). Urinary norepinephrine excretion was unrelated to either mood states or β-adrenergic receptor function. These findings replicate previous reports that anxiety is related to decreased (i.e., desensitized) β-adrenergic receptor sensitivity, even after controlling for age, gender, ethnicity, and body mass index. PMID:17583588

  17. Purification and molecular characterization of the cardiac beta-adrenergic receptor

    SciTech Connect

    Robinson, D.A.; Venter, J.C.; Fraser, C.M.

    1986-05-01

    The porcine ventricle cardiac beta-adrenergic receptor (..beta..AR) is predominantly of the ..beta../sub 2/ subtype. Sucrose density gradient purified porcine ventricle membranes exhibit a high ..beta..AR density of 1 pmol per mg and a K/sub d/ for /sup 125/I-iodocyanopindolol of 180 pM. Digitonin solubilized receptor exhibits ligand binding characteristics identical to those of membrane bound receptor. Stability studies indicate that the solubilized cardiac ..beta..AR has a t/sub 1/2/ of 92 hours. Solubilized receptor is stabilized by occupation with antagonists. Isoelectric focusing indicates a pI = 5.0, in agreement with results obtained for both ..beta../sub 1/AR and ..beta../sub 2/AR isolated from other sources. The cardiac ..beta../sub 1/AR has been purified to homogeneity by affinity chromatography and size exclusion HPLC (2 TSK 2000, 1 TSK 3000). Autoradiograms of purified, radioiodinated receptor preparations subjected to SDS-PAGE revealed a single band with an apparent subunit molecular mass (M/sub r/) of 68 kDa. This subunit M/sub r/ was confirmed in membranes photoaffinity labeled with /sup 125/I-iodocyanopindolol diazirine. A single band was specifically labeled, as evidenced by blocking of photoincorporation by (-) and (+) propranolol with typical ..beta..AR stereoselectivity.

  18. Emerging cardiovascular indications of mineralocorticoid receptor antagonists.

    PubMed

    Parviz, Yasir; Iqbal, Javaid; Pitt, Bertram; Adlam, David; Al-Mohammad, Abdallah; Zannad, Faiez

    2015-04-01

    Mineralocorticoid receptor (MR) antagonism is a well-established treatment modality for patients with hypertension, heart failure, and left ventricular systolic dysfunction (LVSD) post-myocardial infarction (MI). There are emerging data showing potential benefits of MR antagonists in other cardiovascular conditions. Studies have shown association between MR activation and the development of myocardial fibrosis, coronary artery disease, metabolic syndrome, and cerebrovascular diseases. This review examines the preclinical and clinical data of MR antagonists for novel indications including heart failure with preserved ejection fraction (HFPEF), pulmonary arterial hypertension (PAH), arrhythmia, sudden cardiac death, valvular heart disease, metabolic syndrome, renal disease, and stroke. MR antagonists are not licensed for these conditions yet; however, emerging data suggest that indication for MR antagonists are likely to broaden; further studies are warranted.

  19. β-Adrenergic Receptor and Insulin Resistance in the Heart.

    PubMed

    Mangmool, Supachoke; Denkaew, Tananat; Parichatikanond, Warisara; Kurose, Hitoshi

    2017-01-01

    Insulin resistance is characterized by the reduced ability of insulin to stimulate tissue uptake and disposal of glucose including cardiac muscle. These conditions accelerate the progression of heart failure and increase cardiovascular morbidity and mortality in patients with cardiovascular diseases. It is noteworthy that some conditions of insulin resistance are characterized by up-regulation of the sympathetic nervous system, resulting in enhanced stimulation of β-adrenergic receptor (βAR). Overstimulation of βARs leads to the development of heart failure and is associated with the pathogenesis of insulin resistance in the heart. However, pathological consequences of the cross-talk between the βAR and the insulin sensitivity and the mechanism by which βAR overstimulation promotes insulin resistance remain unclear. This review article examines the hypothesis that βARs overstimulation leads to induction of insulin resistance in the heart.

  20. β-Adrenergic Receptor and Insulin Resistance in the Heart

    PubMed Central

    Mangmool, Supachoke; Denkaew, Tananat; Parichatikanond, Warisara; Kurose, Hitoshi

    2017-01-01

    Insulin resistance is characterized by the reduced ability of insulin to stimulate tissue uptake and disposal of glucose including cardiac muscle. These conditions accelerate the progression of heart failure and increase cardiovascular morbidity and mortality in patients with cardiovascular diseases. It is noteworthy that some conditions of insulin resistance are characterized by up-regulation of the sympathetic nervous system, resulting in enhanced stimulation of β-adrenergic receptor (βAR). Over-stimulation of βARs leads to the development of heart failure and is associated with the pathogenesis of insulin resistance in the heart. However, pathological consequences of the cross-talk between the βAR and the insulin sensitivity and the mechanism by which βAR over-stimulation promotes insulin resistance remain unclear. This review article examines the hypothesis that βARs over-stimulation leads to induction of insulin resistance in the heart. PMID:28035081

  1. Overexpression of the alpha1B-adrenergic receptor causes apoptotic neurodegeneration: multiple system atrophy.

    PubMed

    Zuscik, M J; Sands, S; Ross, S A; Waugh, D J; Gaivin, R J; Morilak, D; Perez, D M

    2000-12-01

    Progress toward elucidating the function of alpha1B-adrenergic receptors (alpha1BARs) in the central nervous system has been constrained by a lack of agonists and antagonists with adequate alpha1B-specificity. We have obviated this constraint by generating transgenic mice engineered to overexpress either wild-type or constitutively active alpha1BARs in tissues that normally express the receptor, including the brain. All transgenic lines showed granulovacular neurodegeneration, beginning in alpha1B-expressing domains of the brain and progressing with age to encompass all areas. The degeneration was apoptotic and did not occur in non-transgenic mice. Correspondingly, transgenic mice showed an age-progressive hindlimb disorder that was parkinsonian-like, as demonstrated by rescue of the dysfunction by 3, 4-dihydroxyphenylalanine and considerable dopaminergic-neuronal degeneration in the substantia nigra. Transgenic mice also had a grand mal seizure disorder accompanied by a corresponding dysplasia and neurodegeneration of the cerebral cortex. Both behavioral phenotypes (locomotor impairment and seizure) could be partially rescued with the alpha1AR antagonist terazosin, indicating that alpha1AR signaling participated directly in the pathology. Our results indicate that overstimulation of alpha1BAR leads to apoptotic neurodegeneration with a corresponding multiple system atrophy indicative of Shy-Drager syndrome, a disease whose etiology is unknown.

  2. Locus Coeruleus Stimulation Facilitates Long-Term Depression in the Dentate Gyrus That Requires Activation of β-Adrenergic Receptors

    PubMed Central

    Hansen, Niels; Manahan-Vaughan, Denise

    2015-01-01

    Synaptic plasticity comprises a cellular mechanism through which the hippocampus most likely enables memory formation. Neuromodulation, related to arousal, is a key aspect in information storage. The activation of locus coeruleus (LC) neurons by novel experience leads to noradrenaline release in the hippocampus at the level of the dentate gyrus (DG). We explored whether synaptic plasticity in the DG is influenced by activation of the LC via electrical stimulation. Coupling of test-pulses that evoked stable basal synaptic transmission in the DG with stimulation of the LC induced β-adrenoreceptor-dependent long-term depression (LTD) at perforant path–DG synapses in adult rats. Furthermore, persistent LTD (>24 h) induced by perforant path stimulation also required activation of β-adrenergic receptors: Whereas a β-adrenergic receptor antagonist (propranolol) prevented, an agonist (isoproterenol) strengthened the persistence of LTD for over 24 h. These findings support the hypothesis that persistent LTD in the DG is modulated by β-adrenergic receptors. Furthermore, LC activation potently facilitates DG LTD. This suggests in turn that synaptic plasticity in the DG is tightly regulated by activity in the noradrenergic system. This may reflect the role of the LC in selecting salient information for subsequent synaptic processing in the hippocampus. PMID:24464942

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Medicinal Chemistry of Competitive Kainate Receptor Antagonists

    PubMed Central

    2010-01-01

    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

  9. NMDA Receptor Antagonists for Treatment of Depression

    PubMed Central

    Ates-Alagoz, Zeynep; Adejare, Adeboye

    2013-01-01

    Depression is a psychiatric disorder that affects millions of people worldwide. Individuals battling this disorder commonly experience high rates of relapse, persistent residual symptoms, functional impairment, and diminished well-being. Medications have important utility in stabilizing moods and daily functions of many individuals. However, only one third of patients had considerable improvement with a standard antidepressant after 2 months and all patients had to deal with numerous side effects. The N-methyl-d-aspartate (NMDA) receptor family has received special attention because of its critical role in psychiatric disorders. Direct targeting of the NMDA receptor could result in more rapid antidepressant effects. Antidepressant-like effects of NMDA receptor antagonists have been demonstrated in different animal models. MK-801 (a use-dependent channel blocker), and CGP 37849 (an NMDA receptor antagonist) have shown antidepressant properties in preclinical studies, either alone or combined with traditional antidepressants. A recent development is use of ketamine clinically for refractory depression. The purpose of this review is to examine and analyze current literature on the role of NMDA receptor antagonists for treatment of depression and whether this is a feasible route in drug discovery. PMID:24276119

  10. 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/.

  11. Overlap of dopaminergic, adrenergic, and serotoninergic receptors and complementarity of their subtypes in primate prefrontal cortex

    SciTech Connect

    Goldman-Rakic, P.S.; Lidow, M.S.; Gallager, D.W. )

    1990-07-01

    Quantitative in vitro autoradiography was used to determine and compare the areal and laminar distribution of the major dopaminergic, adrenergic, and serotonergic neurotransmitter receptors in 4 cytoarchitectonic regions of the prefrontal cortex in adult rhesus monkeys. The selective ligands, 3H-SCH-23390, 3H-raclopride, 3H-prazosin, and 3H-clonidine were used to label the D1 and D2 dopamine receptor subtypes and the alpha 1- and alpha 2-adrenergic receptors, respectively, while 125I-iodopindolol was used to detect beta-adrenergic receptors. The radioligands, 3H-5-hydroxytryptamine and 3H-ketanserin labeled, respectively, the 5-HT1 and 5-HT2 receptors. Densitometry was performed on all cortical layers and sublayers for each of the 7 ligands to allow quantitative as well as qualitative comparison among them in each cytoarchitectonic area. Although each monoamine receptor was distributed in a distinctive laminar-specific pattern that was remarkably similar from area to area, there was considerable overlap among the dopaminergic, adrenergic, and serotoninergic receptors, while subtypes of the same receptor class tended to have complementary laminar profiles and different concentrations. Thus, the D1 dopamine, the alpha 1- and alpha 2-adrenergic, and the 5-HT1 receptors were present in highest relative concentration in superficial layers I, II, and IIIa (the S group). In contrast, the beta 1- and beta 2-adrenergic subtypes and the 5-HT2 receptor had their highest concentrations in the intermediate layers, IIIb and IV (the I group), while the D2 receptor was distinguished by relatively high concentrations in the deep layer V compared to all other layers (the D class). Thus, clear laminar differences were observed in the D1 vs D2 dopaminergic, the alpha- vs beta-adrenergic, and the 5-HT1 vs 5-HT2 serotoninergic receptor subtypes in all 4 areas examined.

  12. Molecular Basis of Ligand Dissociation in β-Adrenergic Receptors

    PubMed Central

    González, Angel; Perez-Acle, Tomas; Pardo, Leonardo; Deupi, Xavier

    2011-01-01

    The important and diverse biological functions of β-adrenergic receptors (βARs) have promoted the search for compounds to stimulate or inhibit their activity. In this regard, unraveling the molecular basis of ligand binding/unbinding events is essential to understand the pharmacological properties of these G protein-coupled receptors. In this study, we use the steered molecular dynamics simulation method to describe, in atomic detail, the unbinding process of two inverse agonists, which have been recently co-crystallized with β1 and β2ARs subtypes, along four different channels. Our results indicate that this type of compounds likely accesses the orthosteric binding site of βARs from the extracellular water environment. Importantly, reconstruction of forces and energies from the simulations of the dissociation process suggests, for the first time, the presence of secondary binding sites located in the extracellular loops 2 and 3 and transmembrane helix 7, where ligands are transiently retained by electrostatic and Van der Waals interactions. Comparison of the residues that form these new transient allosteric binding sites in both βARs subtypes reveals the importance of non-conserved electrostatic interactions as well as conserved aromatic contacts in the early steps of the binding process. PMID:21915263

  13. Prenatal exposure to methylmercury alters development of adrenergic receptor binding sites in peripheral sympathetic target tissues

    SciTech Connect

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

    1987-01-01

    In order to assess the impact of prenatal exposure to methylmercury on sympathetic neurotransmission, effects on development of adrenergic receptor binding sites in peripheral tissues was evaluated. In the liver, methylmercury produced a dose-dependent increase in alpha/sub 1/, alpha/sub 2/, and beta-receptor binding of radioliganda throughout the first 5 weeks of postnatal life. Similarly, renal alpha-receptor subtypes showed increased binding capabilities, but binding to alpha-receptor sites was reduced. At least some of the changes in receptors appear to be of functional significance, as physiological reactivity to adrenergic stimulation is altered in the same directions in these two tissues. The actions of methylmercury displayed tissue specificity in that the same receptor populations were largely unaffected in other tissues (lung, heart). These results suggest that methylmercury exposure in utero alters adrenergic responses through targeted effects on postsynaptic receptor populations in specific tissues.

  14. 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.

  15. Immobility from administration of the alpha1-adrenergic antagonist, terazosin, in the IVth ventricle in rats.

    PubMed

    Stone, Eric A; Lin, Yan; Quartermain, David

    2003-12-26

    Brain alpha1-adrenoceptors have been shown to be essential for motor activity and movement in mice using intraventricular injection of alpha1-antagonists. To facilitate subsequent neuroanatomical mapping of these receptors, the present study was undertaken to replicate these effects in the rat. Rats were administered the alpha1-antagonist, terazosin, in the absence and presence of the alpha1-agonist, phenylephrine, in the IVth ventricle and were tested for their motor activity responses to an environmental change. Terazosin was found to produce a dose-dependent, virtually complete cessation of behavioral activity that was reversed by coinfusion of phenylephrine. The results could not be explained by sedation. It is concluded that central alpha1-adrenoceptors are essential for behavioral activation in rats as in mice.

  16. Development of Kappa Opioid Receptor Antagonists

    PubMed Central

    Carroll, F. Ivy; Carlezon, William A.

    2013-01-01

    Kappa opioid receptors (KORs) belong to the G-protein coupled class of receptors (GPCRs). They are activated by the endogenous opioid peptide dynorphin (DYN) and expressed at particularly high levels within brain areas implicated in modulation of motivation, emotion, and cognitive function. Chronic activation of KORs in animal models has maladaptive effects including increases in behaviors that reflect depression, the propensity to engage in drug-seeking behavior, and drug craving. The fact that KOR activation has such a profound influence on behaviors often triggered by stress has led to interest in selective KOR antagonists as potential therapeutic agents. This perspective provides a description of preclinical research conducted in the development of several different classes of selective KOR antagonists, a summary of the clinical studies conducted thus far, and recommendations for the type of work needed in the future to determine if these agents would be useful as pharmacotherapies for neuropsychiatric illness. PMID:23360448

  17. Alpha 2-adrenergic receptors influence tyrosine hydroxylase activity in retinal dopamine neurons.

    PubMed

    Iuvone, P M; Rauch, A L

    1983-12-12

    Dopamine (DA) is a putative neurotransmitter in a population of interneurons in the mammalian retina that are activated by photic stimulation. Pharmacological studies were conducted to determine if alpha 2-adrenergic receptors influence the activity of retinal tyrosine hydroxylase (TH), a biochemical indicator of changes in the activity of the DA-containing neurons. TH activity was low in dark-adapted retinas and high in light-exposed retinas. Systemic administration of the alpha 2-adrenoceptor antagonists, yohimbine and piperoxane, to dark-adapted rats significantly stimulated TH activity. This effect was apparently mediated locally within the retina because the response could also be elicited by direct injection of yohimbine into the vitreous. The dose-response relationships for the effects of alpha 2-adrenoceptor antagonists on retinal TH activity were similar to those for the effects on brain noradrenergic neurons, where alpha 2-adrenoceptors have been shown to be involved in the autoregulation of neuronal activity. Clonidine, an alpha 2-adrenoceptor agonist, had no effect when administered alone to dark-adapted rats, but it attenuated the stimulatory effect of yohimbine. In contrast, clonidine decreased TH activity of light-exposed retinas, an effect that was reversed by yohimbine. These observations suggest that alpha 2-adrenoceptors influence the activity of retinal DA-containing neurons.

  18. 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).

  19. β2-adrenergic receptor control of endosomal PTH receptor signaling via Gβγ

    PubMed Central

    Jean-Alphonse, Frédéric G; Wehbi, Vanessa L; Chen, Jingming; Noda, Masaki; Taboas, Juan M; Xiao, Kunhong; Vilardaga, Jean-Pierre

    2017-01-01

    Cells express several G-protein-coupled receptors (GPCRs) at their surfaces, transmitting simultaneous extracellular hormonal and chemical signals into cells. A comprehensive understanding of mechanisms underlying the integrated signaling response induced by distinct GPCRs is thus required. Here we found that the β2-adrenergic receptor, which induces a short cAMP response, prolongs nuclear cAMP and protein kinase A (PKA) activation by promoting endosomal cAMP production in parathyroid hormone (PTH) receptor signaling through the stimulatory action of G protein Gβγ subunits on adenylate cyclase type 2. PMID:28024151

  20. 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

  1. 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.

  2. NEURON SPECIFIC α-ADRENERGIC RECEPTOR EXPRESSION IN HUMAN CEREBELLUM: IMPLICATIONS FOR EMERGING CEREBELLAR ROLES IN NEUROLOGIC DISEASE

    PubMed Central

    SCHAMBRA, U. B.; MACKENSEN, G. B.; STAFFORD-SMITH, M.; HAINES, D. E.; SCHWINN, D. A.

    2008-01-01

    Recent data suggest novel functional roles for cerebellar involvement in a number of neurologic diseases. Function of cerebellar neurons is known to be modulated by norepinephrine and adrenergic receptors. The distribution of adrenergic receptor subtypes has been described in experimental animals, but corroboration of such studies in the human cerebellum, necessary for drug treatment, is still lacking. In the present work we studied cell-specific localizations of α1 adrenergic receptor subtype mRNA (α1a, α1b, α1d), and α2 adrenergic receptor subtype mRNA (α2a, α2b, α2c) by in situ hybridization on cryostat sections of human cerebellum (cortical layers and dentate nucleus). We observed unique neuron-specific α1 adrenergic receptor and α2 adrenergic receptor subtype distribution in human cerebellum. The cerebellar cortex expresses mRNA encoding all six α adrenergic receptor subtypes, whereas dentate nucleus neurons express all subtype mRNAs, except α2a adrenergic receptor mRNA. All Purkinje cells label strongly for α2a and α2b adrenergic receptor mRNA. Additionally, Purkinje cells of the anterior lobe vermis (lobules I to V) and uvula/tonsil (lobules IX/HIX) express α1a and α2c subtypes, and Purkinje cells in the ansiform lobule (lobule HVII) and uvula/tonsil express α1b and α2c adrenergic receptor subtypes. Basket cells show a strong signal for α1a, moderate signal for α2a and light label for α2b adrenergic receptor mRNA. In stellate cells, besides a strong label of α2a adrenergic receptor mRNA in all and moderate label of α2b message in select stellate cells, the inner stellate cells are also moderately positive for α1b adrenergic receptor mRNA. Granule and Golgi cells express high levels of α2a and α2b adrenergic receptor mRNAs. These data contribute new information regarding specific location of adrenergic receptor subtypes in human cerebellar neurons. We discuss our observations in terms of possible modulatory roles of adrenergic

  3. Platelet alpha 2-adrenergic receptors in major depressive disorder. Binding of tritiated clonidine before and after tricyclic antidepressant drug treatment

    SciTech Connect

    Garcia-Sevilla, J.A.; Zis, A.P.; Hollingsworth, P.J.; Greden, J.F.; Smith, C.B.

    1981-12-01

    The specific binding of tritiated (3H)-clonidine, an alpha 2-adrenergic receptor agonist, to platelet membranes was measured in normal subjects and in patients with major depressive disorder. The number of platelet alpha 2-adrenergic receptors from the depressed group was significantly higher than that found in platelets obtained from the control population. Treatment with tricyclic antidepressant drugs led to significant decreases in the number of platelet alpha 2-adrenergic receptors. These results support the hypothesis that the depressive syndrome is related to an alpha 2-adrenergic receptor supersensitivity and that the clinical effectiveness of tricyclic antidepressant drugs is associated with a decrease in the number of these receptors.

  4. 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.

  5. Binding of amyloid beta peptide to beta2 adrenergic receptor induces PKA-dependent AMPA receptor hyperactivity.

    PubMed

    Wang, Dayong; Govindaiah, G; Liu, Ruijie; De Arcangelis, Vania; Cox, Charles L; Xiang, Yang K

    2010-09-01

    Progressive decrease in neuronal function is an established feature of Alzheimer's disease (AD). Previous studies have shown that amyloid beta (Abeta) peptide induces acute increase in spontaneous synaptic activity accompanied by neurotoxicity, and Abeta induces excitotoxic neuronal death by increasing calcium influx mediated by hyperactive alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors. An in vivo study has revealed subpopulations of hyperactive neurons near Abeta plaques in mutant amyloid precursor protein (APP)-transgenic animal model of Alzheimer's disease (AD) that can be normalized by an AMPA receptor antagonist. In the present study, we aim to determine whether soluble Abeta acutely induces hyperactivity of AMPA receptors by a mechanism involving beta(2) adrenergic receptor (beta(2)AR). We found that the soluble Abeta binds to beta(2)AR, and the extracellular N terminus of beta(2)AR is critical for the binding. The binding is required to induce G-protein/cAMP/protein kinase A (PKA) signaling, which controls PKA-dependent phosphorylation of GluR1 and beta(2)AR, and AMPA receptor-mediated excitatory postsynaptic currents (EPSCs). beta(2)AR and GluR1 also form a complex comprising postsynaptic density protein 95 (PSD95), PKA and its anchor AKAP150, and protein phosphotase 2A (PP2A). Both the third intracellular (i3) loop and C terminus of beta(2)AR are required for the beta(2)AR/AMPA receptor complex. Abeta acutely induces PKA phosphorylation of GluR1 in the complex without affecting the association between two receptors. The present study reveals that non-neurotransmitter Abeta has a binding capacity to beta(2)AR and induces PKA-dependent hyperactivity in AMPA receptors.

  6. Pharmacogenomics of beta-adrenergic receptors and their accessory signaling proteins in heart failure.

    PubMed

    Dorn, Gerald W; Liggett, Stephen B

    2008-12-01

    beta-Adrenergic receptors (betaAR) are widely expressed on cardiovascular cells. Pharmacological stimulation or blockade of betaAR signaling is the therapeutic mainstay in cardiogenic shock, hypertension, ischemia, arrhythmias, and heart failure. Interindividual variability in the response to betaAR agonists and antagonists has prompted examination of variability in the genes encoding betaAR signaling pathway members. Prominent among the genes that have been examined so far in heart failure are the beta(1)AR, beta(2)AR, and G-protein-coupled receptor kinase 5 (GRK5). Each has nonsynonymous polymorphisms that alter amino acid sequence and protein function and regulation in cell-based systems, genetically altered mouse models, or human hearts. Here, we review these phenotypes and results from published clinical studies, with a focus on heart failure pharmacogenomics. Thus far, very few studies have utilized analogous protocols or drugs, and discrepancies in the clinical studies are apparent. A compelling approach is the use of multiple methods to understand the molecular, cellular, and organ phenotypes of a variant and couple these with clinical studies designed to specifically address the relevance of those phenotypes in humans. Undoubtedly, additional loci will be identified, and together, will provide for genetically driven, individualized treatments for heart failure.

  7. Investigation of orexin-2 selective receptor antagonists: Structural modifications resulting in dual orexin receptor antagonists.

    PubMed

    Skudlarek, Jason W; DiMarco, Christina N; Babaoglu, Kerim; Roecker, Anthony J; Bruno, Joseph G; Pausch, Mark A; O'Brien, Julie A; Cabalu, Tamara D; Stevens, Joanne; Brunner, Joseph; Tannenbaum, Pamela L; Wuelfing, W Peter; Garson, Susan L; Fox, Steven V; Savitz, Alan T; Harrell, Charles M; Gotter, Anthony L; Winrow, Christopher J; Renger, John J; Kuduk, Scott D; Coleman, Paul J

    2017-03-15

    In an ongoing effort to explore the use of orexin receptor antagonists for the treatment of insomnia, dual orexin receptor antagonists (DORAs) were structurally modified, resulting in compounds selective for the OX2R subtype and culminating in the discovery of 23, a highly potent, OX2R-selective molecule that exhibited a promising in vivo profile. Further structural modification led to an unexpected restoration of OX1R antagonism. Herein, these changes are discussed and a rationale for selectivity based on computational modeling is proposed.

  8. [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…

  9. β1-adrenergic receptor activation enhances memory in Alzheimer's disease model

    PubMed Central

    Coutellier, Laurence; Ardestani, Pooneh Memar; Shamloo, Mehrdad

    2014-01-01

    Objective Deficits in social recognition and learning of social cues are major symptoms of neurodegenerative disorders such as Alzheimer's disease (AD). Here, we studied the role of β1-noradrenergic signaling in cognitive function to determine whether it could be used as a potential therapeutic target for AD. Methods Using pharmacological, biochemical, and behavioral tools, we assessed social recognition and the β1-adrenergic receptor (ADR) and its downstream protein kinase A (PKA)/phospho-cAMP response element-binding protein (pCREB) signaling cascade in the medial amygdala (MeA) in Thy1-hAPPLond/Swe+(APP) mouse model of AD. Results Our results demonstrated that APP mice display a significant social recognition deficit which is dependent on the β1-adrenergic system. Moreover, betaxolol, a selective β1-ADR antagonist, impaired social but not object/odor learning in C57Bl/6 mice. Our results identifies activation of the PKA/pCREB downstream of β1-ADR in MeA as responsible signaling cascade for learning of social cues in MeA. Finally, we found that xamoterol, a selective β1-ADR partial agonist, rescued the social recognition deficit of APP mice by increasing nuclear pCREB. Interpretation Our data indicate that activation of β1-ADR in MeA is essential for learning of social cues, and that an impairment of this cascade in AD may contribute to pathogenesis and cognitive deficits. Therefore, selective activation of β1-ADR may be used as a therapeutic approach to rescue memory deficits in AD. Further safety and translational studies will be needed to ensure the safety of this approach. PMID:24883337

  10. 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.

  11. 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.

  12. Role of postsynaptic alpha-adrenergic receptors in the beta-adrenergic stimulation of melatonin production in the Syrian hamster pineal gland in organ culture.

    PubMed

    Santana, C; Guerrero, J M; Reiter, R J; Menendez-Pelaez, A

    1989-01-01

    The role played by postsynaptic alpha-adrenergic receptors in the stimulation of pineal melatonin production was investigated in the Syrian hamster. The studies were conducted using organ cultured pineal glands collected from both anatomically intact and superior cervical ganglionectomized hamsters. Results obtained indicate that phenylephrine, an alpha-adrenergic agonist, by itself has no effect in promoting melatonin production; however, it potentiates the stimulatory effects of isoproterenol, a beta-adrenergic agonist, on pineal melatonin production in nonoperated hamsters. Similar observations were obtained with pineal glands whose presynaptic terminals were removed by prior superior cervical ganglionectomy. However, a longer incubation time was required (4-6 hours vs. 2 hours) with pineal glands taken from ganglionectomized animals. Apparently, beta-adrenergic activation is an absolute requirement to stimulate pineal melatonin production, and an alpha-adrenergic receptor mechanism potentiates beta-adrenergic activation. In addition, the findings obtained with denervated pineal glands suggest that the regulation of pineal melatonin production by both alpha- and beta-adrenergic mechanisms is through receptors located on postsynaptic structures.

  13. Roles of the locus coeruleus and adrenergic receptors in brain-mediated hypothalamic-pituitary-adrenal axis responses to intracerbroventricular alcohol

    PubMed Central

    Selvage, Dan

    2011-01-01

    Background Alcohol activates the hypothalamic-pituitary-adrenal (HPA) axis through its actions in both the periphery and the CNS. The studies presented here were designed to test the CNS-specific noradrenergic mechanisms by which alcohol stimulates HPA activity in the male rat. Methods We used an experimental paradigm in which a small, non-toxic amount (5 microliters) of alcohol was slowly microinfused intracerebroventricularly (icv). Alcohol was administered icv to animals with lesions of the locus coeruleus, or in animals pretreated with alpha- or beta-adrenergic receptor antagonists. Hormonal HPA activation was determined by measuring secretion of the pituitary stress hormone adrenocorticotropin (ACTH). Neuronal activation was determined by quantification of the expression of the transcription factor c-fos (Fos). Results As expected, icv alcohol stimulated ACTH secretion from the pituitary and Fos expression in the paraventricular nucleus of the hypothalamus (PVN). Bilateral electrolytic locus coeruleus lesions blocked the ability of icv alcohol to stimulate ACTH secretion. Pretreatment with icv propranolol increased basal ACTH secretion levels, but icv alcohol did not increase this effect. Propranolol also blunted icv alcohol-induced PVN Fos expression. A low dose of phenoxybenzamine, an alpha-adrenergic receptor antagonist, did not affect the ability of icv alcohol to stimulate ACTH release. However, a higher dose of the drug was able to block the ACTH response to icv alcohol. Despite this, phenoxybenzamine did not inhibit alcohol-induced Fos expression. Icv pretreatment with corynanthine, a selective alpha-1 adrenergic receptor antagonist, modestly raised basal ACTH levels, and blocked the icv alcohol-induced secretion of this hormone. Conclusions These results indicate the LC and NE play important roles in HPA activation caused by icv alcohol administration, but that the specific adrenergic receptor subtypes involved in this phenomenon still need to be

  14. β-Adrenergic receptor mediated increases in activation and function of natural killer cells following repeated social disruption.

    PubMed

    Tarr, Andrew J; Powell, Nicole D; Reader, Brenda F; Bhave, Neela S; Roloson, Amanda L; Carson, William E; Sheridan, John F

    2012-11-01

    Natural killer (NK) cells are specialized innate lymphocytes important in the early defense against tumor and virus bearing cells. Many factors influence the immune system's effectiveness against pathogens, including stress. Social disruption (SDR) "primes" macrophages/monocytes and dendritic cells thereby enhancing their anti-microbial function. What remains unclear is whether similar responses are evident in NK cells. Current studies investigated the cellular distribution and activation/inhibitory phenotypes of NK cells in the spleen, lung, and blood of C57BL/6 male mice following SDR. Furthermore, cytolytic activity and anti-viral cytokine production of splenic NK cells were determined. Lastly, β-adrenergic receptor (β-AR) signaling was investigated to determine possible mechanisms behind the SDR-induced NK cell alterations. Results indicated NK cells from SDR mice have increased expression of CD16 and CD69 and reduced NKG2a and Ly49a expression on splenic CD3-/DX5+ NK cells indicative of an activated phenotype, both immediately and 14h post-SDR. Administration of propranolol (10mg/kg; non-selective β-adrenergic receptor antagonist) was shown to block these "priming" effects at the 14h time-point. In the lung, SDR had similar effects on activation and inhibitory receptors 14h post-SDR, however no alterations were evident in the blood besides increased NK cells directly after SDR. Additionally, splenic NK cells from SDR mice had increased CD107a surface expression, cytolytic activity, and IFN-γ production was increased upon costimulation with IgG and IL-2 ex vivo. Collectively, these data suggest that social stress "primes" NK cells in the spleen and lung to be more proficient in their cytolytic and anti-viral/tumor effecter functions through β-adrenergic receptor dependent signaling.

  15. 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

  16. The role of adrenergic receptors in the motility of duodenum and choledochoduodenal junction in the pig.

    PubMed

    Blichowski, A; Andrzejewski, W; Gaszyński, W; Kozulski, W

    1977-01-01

    The role of adenergic receptors in the motility of duodenum and choledochoduodenal junction in the pig. Acta Physiol. Pol., 1977, 28 (6): 521-528. The choldeochoduodenal junction in the Vietnamese pig is functionally and anatomically a part of duodenal wall. In view of this, investigations were carried out for establishing the role of adrenergic receptors in the development of motor function of this part of the intestinal tract. The experiments were performed on domestic Vietnamese pigs (Sus scrofa domestica) and they showed that after stimulation of alpha and beta adrenergic receptors the motor activity of the duodenal muscular coat and the choledochoduodenal junction is inhibited. The obtained results suggest similar reactions of the adrenergic receptors in both examined parts of the intestinal tract in the pig.

  17. Comparative peptide mapping of adrenergic and cholinergic neutrotransmitter receptors by reverse-HPLC

    SciTech Connect

    Kerlavage, A.R.; Fraser, C.M.; Venter, J.C.; Shreeve, S.M.

    1986-05-01

    The authors have developed a methodology for unambiguously identifying neutrotransmitter receptor proteins and comparing structural features of related receptors as well as those in different classes. These techniques have been applied to the study of the ..cap alpha..- and ..beta..-adrenergic receptors as well as the muscarinic and nicotinic cholinergic receptors. The method involves comparative peptide mapping of total proteolytic digests of receptor proteins by microbore reverse-phase HPLC in conjunction with covalent modification by specific receptor ligands or (/sup 125/I)-labeling. Femtomole amounts of receptor can be analyzed. The maps of all the (/sup 125/I)-labeled receptors contain between 20 and 25 peaks and each receptor has a unique profile although all are similar in the very hydrophobic region of the map. The ..cap alpha../sub 2/-adrenergic receptor from human platelets has a higher total percentage of hydrophilic peaks than either the guinea pig lung ..beta../sub 2/-adrenergic receptor or the porcine atria muscarinic receptor. Two forms of the muscarinic receptor have very similar but clearly distinct profiles. The nicotinic receptor subunits show a higher degree of homology by this method than was revealed by previous mapping studies which utilized SDS-PAGE or thin-layer techniques.

  18. Design and optimization of quinazoline derivatives as melanin concentrating hormone receptor 1 (MCHR1) antagonists.

    PubMed

    Sasmal, Sanjita; Balaji, Gade; Kanna Reddy, Hariprasada R; Balasubrahmanyam, D; Srinivas, Gujjary; Kyasa, Shivakumar; Sasmal, Pradip K; Khanna, Ish; Talwar, Rashmi; Suresh, J; Jadhav, Vikram P; Muzeeb, Syed; Shashikumar, Dhanya; Harinder Reddy, K; Sebastian, V J; Frimurer, Thomas M; Rist, Øystein; Elster, Lisbeth; Högberg, Thomas

    2012-05-01

    Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays a role in metabolic and CNS disorders. The modeling-supported design, synthesis and multi-parameter optimization (biological activity, solubility, metabolic stability, hERG) of novel quinazoline derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified. Clusters of refined hMCHR1 homology models derived from the X-ray structure of the β2-adrenergic receptor, including extracellular loops, were developed and used to guide the design.

  19. β2-Adrenergic receptor solutions for structural biology analyzed with microscale NMR diffusion measurements.

    PubMed

    Horst, Reto; Stanczak, Pawel; Stevens, Raymond C; Wüthrich, Kurt

    2013-01-02

    Microcoil NMR measurements were performed to determine the final composition of solutions of the β(2)-adrenergic receptor (β(2)AR) reconstituted with a detergent and to study the hydrodynamic properties of the detergent micelles containing β(2)AR. Standards are established for the reproducible preparation of G-protein-coupled receptor solutions for crystallization trials and solution NMR studies.

  20. Possible involvement of parotid beta-adrenergic receptors in the etiology of sialadenosis.

    PubMed

    Chilla, R; Witzemann, V; Opaitz, M; Arglebe, C

    1981-01-01

    The concentration of beta-adrenergic receptors was determined in rat and human parotid glands, in normal tissue as well as after sympathetic denervation of the rat, and in human sialadenosis. Receptor levels were clearly elevated after denervation of the rat and in sialadenosis. The possible implications of these findings for the etiology of human sialadenosis are discussed.

  1. β-Adrenergic Receptor-Mediated Cardiac Contractility is Inhibited via Vasopressin Type 1A-Receptor-Dependent Signaling

    PubMed Central

    Tilley, Douglas G.; Zhu, Weizhong; Myers, Valerie D.; Barr, Larry A.; Gao, Erhe; Li, Xue; Song, Jianliang; Carter, Rhonda L.; Makarewich, Catherine A.; Yu, Daohai; Troupes, Constantine D.; Grisanti, Laurel A.; Coleman, Ryan C.; Koch, Walter J.; Houser, Steven R.; Cheung, Joseph Y.; Feldman, Arthur M.

    2014-01-01

    Background Enhanced arginine vasopressin (AVP) levels are associated with increased mortality during end-stage human heart failure (HF), and cardiac AVP type 1A receptor (V1AR) expression becomes increased. Additionally, mice with cardiac-restricted V1AR overexpression develop cardiomyopathy and decreased β-adrenergic receptor (βAR) responsiveness. This led us to hypothesize that V1AR signaling regulated βAR responsiveness and in doing so contributes to HF development. Methods and Results Transaortic constriction resulted in decreased cardiac function and βAR density and increased cardiac V1AR expression, effects reversed by a V1AR-selective antagonist. Molecularly, V1AR stimulation led to decreased βAR ligand affinity, as well as βAR-induced Ca2+ mobilization and cAMP generation in isolated adult cardiomyocytes, effects recapitulated via ex vivo Langendorff analysis. V1AR-mediated regulation of βAR responsiveness was demonstrated to occur in a previously unrecognized Gq protein-independent/GRK-dependent manner. Conclusions This newly discovered relationship between cardiac V1AR and βAR may be informative for the treatment of patients with acute decompensated HF and elevated AVP. PMID:25205804

  2. 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.

  3. Involvement of central beta2-adrenergic, NMDA and thromboxane A2 receptors in the pressor effect of anandamide in rats.

    PubMed

    Malinowska, B; Zakrzeska, A; Kurz, C M; Göthert, M; Kwolek, G; Wielgat, P; Braszko, J J; Schlicker, E

    2010-04-01

    Intravenous (i.v.) injection of the endocannabinoid anandamide induces triphasic cardiovascular responses, including a pressor effect mediated via unknown central and peripheral mechanism(s). The aim of the present study was to determine the central mechanism(s) responsible for the pressor response to anandamide. For this purpose, the influence of antagonists at thromboxane A(2) TP (sulotroban, daltroban, SQ 29548), NMDA (MK-801) and beta(2)-adrenergic receptors (ICI 118551) on the pressor effect induced by i.v. and intracerebroventricularly (i.c.v.) administered anandamide was examined in urethane-anaesthetized rats. Anandamide (1.5-3 micromol/kg, i.v.) or its stable analogue methanandamide (0.75 micromol/kg, i.v.) increased blood pressure by 25%. Anandamide (0.03 mumol per animal i.c.v.) caused a pure pressor effect (by 20%) but only in the presence of antagonists of CB(1) and TRPV1 receptors. The effects of cannabinoids (i.v. or i.c.v.) were diminished by i.v. daltroban, sulotroban (10 mumol/kg each), and/or SQ 29548 (1 mumol/kg). The effect of anandamide i.v. was reduced by SQ 29548 (0.02 mumol per animal i.c.v.) and by the thromboxane A(2) synthesis inhibitor furegrelate i.c.v. (1.8 micromol per animal). ICI 118551, MK-801 (1 micromol/kg i.v. each), and bilateral adrenalectomy diminished the effect of anandamide i.c.v. Sulotroban (i.v.) failed to affect the response to anandamide (i.v.) in pithed rats, and anandamide and methanandamide did not bind to TP receptors in rat platelets. The present study suggests that central beta(2)-adrenergic, NMDA and thromboxane A(2) receptors are involved in the anandamide-induced adrenal secretion of catecholamines and their pressor effect in urethane-anaesthetized rats.

  4. 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

  5. Mammalian. beta. /sub 1/- and. beta. /sub 2/-adrenergic receptors: immunological and structural comparison

    SciTech Connect

    Moxham, C.P.; George, S.T.; Graziano, M.P.; Brandwein, H.J.; Malbon, C.C.

    1986-11-05

    ..beta../sub 1/- and ..beta../sub 2/-adrenergic receptors, pharmacologically distinct proteins, have been reported to be structurally dissimilar. In the present study three techniques were employed to compare the nature of mammalian ..beta../sub 1/- and ..beta../sub 2/-adrenergic receptors. Antibodies against each of the receptor subtypes were raised separately. Polyclonal antisera against ..beta../sub 1/-receptors of rat fat cells were raised in mice, and antisera against ..beta../sub 2/-receptors of guinea pig lung were raised in rabbits. Receptors purified from rat fat cells (..beta../sub 1/-), S49 mouse lymphoma cells (..beta../sub 2/-), and rat liver (..beta../sub 2/-) were probed with these antisera. Each anti-receptor antisera demonstrated the ability to immunoprecipitate purified receptors of both ..beta../sub 1/- and ..beta../sub 2/-subtypes. The mobility of ..beta..-receptors subjected to polyacrylamide gel electrophoresis was probed using antireceptor antibodies and nitrocellulose blots of the gels. Fat cell ..beta../sub 1/-adrenergic receptors display M/sub r/ = 67,000 under reducing conditions and M/sub r/ = 54,000 under nonreducing conditions, as previously reported. Both ..beta../sub 1/- and ..beta../sub 2/-receptors displayed this same shift in electrophoretic mobility observed in the presence as compared to the absence of disulfide bridge-reducing agents, as detected both by autoradiography of the radiolabeled receptors and by immunoblotting of native receptors. Finally, isoelectric focusing of purified radioiodinated ..beta../sub 1/- and ..beta../sub 2/-adrenergic receptors revealed identical isoelectric points. These data are the first to provide analyses of immunological, structural, and biochemical features of ..beta../sub 1/- and ..beta../sub 2/-subtypes in tandem and underscore the structural similarities that exist between these pharmacologically distinct receptors.

  6. 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.

  7. Distribution of adrenergic receptors in the enteric nervous system of the guinea pig, mouse, and rat.

    PubMed

    Nasser, Yasmin; Ho, Winnie; Sharkey, Keith A

    2006-04-10

    Adrenergic receptors in the enteric nervous system (ENS) are important in control of the gastrointestinal tract. Here we describe the distribution of adrenergic receptors in the ENS of the ileum and colon of the guinea pig, rat, and mouse by using single- and double-labelling immunohistochemistry. In the myenteric plexus (MP) of the rat and mouse, alpha2a-adrenergic receptors (alpha2a-AR) were widely distributed on neurons and enteric glial cells. alpha2a-AR mainly colocalized with calretinin in the MP, whereas submucosal alpha2a-AR neurons colocalized with vasoactive intestinal polypeptide (VIP), neuropeptide Y, and calretinin in both species. In the guinea pig ileum, we observed widespread alpha2a-AR immunoreactivity on nerve fibers in the MP and on VIP neurons in the submucosal plexus (SMP). We observed extensive beta1-adrenergic receptor (beta1-AR) expression on neurons and nerve fibers in both the MP and the SMP of all species. Similarly, the beta2-adrenergic receptor (beta2-AR) was expressed on neurons and nerve fibers in the SMP of all species, as well as in the MP of the mouse. In the MP, beta1- and beta2-AR immunoreactivity was localized to several neuronal populations, including calretinin and nitrergic neurons. In the SMP of the guinea pig, beta1- and beta2-AR mainly colocalized with VIP, whereas, in the rat and mouse, beta1- and beta2-AR were distributed among the VIP and calretinin populations. Adrenergic receptors were widely localized on specific neuronal populations in all species studied. The role of glial alpha2a-AR is unknown. These results suggest that sympathetic innervation of the ENS is directed toward both enteric neurons and enteric glia.

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

    PubMed

    O'Dell, Thomas J; Connor, Steven A; Guglietta, Ryan; Nguyen, Peter V

    2015-09-01

    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.

  9. 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.

  10. cap alpha. /sub 2/-Adrenergic receptors in platelet membranes of depressed patients: no change in number of /sup 3/H-yohimbine affinity

    SciTech Connect

    Daiguji, M.I.; Meltzer, H.Y.; Tong, C.; U'Pritchard, D.C.; Young, M.; Kravitz, H.

    1981-11-16

    The ..cap alpha../sub 2/-adrenergic receptor density in platelet membranes from normal controls and depressed patients was studied using /sup 3/H-yohimbine, a potent ..cap alpha../sub 2/-adrenergic antagonist, as a radioligand. The KD values of /sup 3/H-yohimbine in control and depressed patient samples were 0.92 +/- 0.07 nM and 0.97 +/- 0.06 nM, respectively. The Bmax values of controls and depressed patients were 240 +/- 19 fmoles/mg protein (125 +/- 13 receptor/platelet, R/PL) and 204 +/- 20 fmoles/mg protein (130 +/- 14 R/PL), respectively. There were no significant differences between the KD and Bmax values of the two groups.

  11. Antibodies to β adrenergic and muscarinic cholinergic receptors in patients with Chronic Fatigue Syndrome.

    PubMed

    Loebel, Madlen; Grabowski, Patricia; Heidecke, Harald; Bauer, Sandra; Hanitsch, Leif G; Wittke, Kirsten; Meisel, Christian; Reinke, Petra; Volk, Hans-Dieter; Fluge, Øystein; Mella, Olav; Scheibenbogen, Carmen

    2016-02-01

    Infection-triggered disease onset, chronic immune activation and autonomic dysregulation in CFS point to an autoimmune disease directed against neurotransmitter receptors. Autoantibodies against G-protein coupled receptors were shown to play a pathogenic role in several autoimmune diseases. Here, serum samples from a patient cohort from Berlin (n=268) and from Bergen with pre- and post-treatment samples from 25 patients treated within the KTS-2 rituximab trial were analysed for IgG against human α and β adrenergic, muscarinic (M) 1-5 acetylcholine, dopamine, serotonin, angiotensin, and endothelin receptors by ELISA and compared to a healthy control cohort (n=108). Antibodies against β2, M3 and M4 receptors were significantly elevated in CFS patients compared to controls. In contrast, levels of antibodies against α adrenergic, dopamine, serotonin, angiotensin, and endothelin receptors were not different between patients and controls. A high correlation was found between levels of autoantibodies and elevated IgG1-3 subclasses, but not with IgG4. Further patients with high β2 antibodies had significantly more frequently activated HLA-DR+ T cells and more frequently thyreoperoxidase and anti-nuclear antibodies. In patients receiving rituximab maintenance treatment achieving prolonged B-cell depletion, elevated β2 and M4 receptor autoantibodies significantly declined in clinical responder, but not in non-responder. We provide evidence that 29.5% of patients with CFS had elevated antibodies against one or more M acetylcholine and β adrenergic receptors which are potential biomarkers for response to B-cell depleting therapy. The association of autoantibodies with immune markers suggests that they activate B and T cells expressing β adrenergic and M acetylcholine receptors. Dysregulation of acetylcholine and adrenergic signalling could also explain various clinical symptoms of CFS.

  12. 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

  13. The α2-adrenergic receptor agonist, clonidine, reduces alcohol drinking in alcohol-preferring (P) rats.

    PubMed

    Rasmussen, Dennis D; Alexander, Laura; Malone, Julia; Federoff, David; Froehlich, Janice C

    2014-09-01

    Evidence suggests that noradrenergic signaling may play a role in mediating alcohol-drinking behavior in both rodents and humans. We have investigated this possibility by administering clonidine to alcohol-drinking rats selectively bred for alcohol preference (P line). Clonidine is an α2-adrenergic receptor agonist which, at low doses, inhibits noradrenergic signaling by decreasing norepinephrine release from presynaptic noradrenergic neurons. Adult male P rats were given 24 h access to food and water and scheduled access to a 15% (v/v) alcohol solution for 2 h daily. Rats received intra-peritoneal (IP) injections with clonidine (0, 10, 20, 40, or 80 μg/kg body weight [BW], 10-11 rats/treatment group) once/day at 30 min prior to onset of the daily 2 h alcohol access period for 2 consecutive days. Clonidine, in doses of 40 or 80 μg/kg BW, significantly reduced alcohol intake on both days of treatment (p<0.001). Two weeks later, rats were treated with clonidine for 5 consecutive days and clonidine, in doses of 40 or 80 μg/kg BW, reduced alcohol intake on all 5 treatment days (p < 0.001). Clonidine did not alter water consumption during the daily 2 h free-choice between alcohol and water. In a separate group of male P rats, clonidine (40 μg/kg BW) suppressed intake of a saccharin solution (0.04 g/L). These results are consistent with and complement our previous findings that the α1-adrenergic receptor antagonist, prazosin, decreases voluntary alcohol drinking in alcohol-preferring rats, but suggests that effects of clonidine may not be specific for alcohol. The results suggest that although activation of the noradrenergic system plays an important role in mediating voluntary alcohol drinking, care is needed in selecting which drugs to use to suppress central noradrenergic signaling in order to maximize the selectivity of the drugs for treating alcohol-use disorders.

  14. Localization of the fourth membrane spanning domain as a ligand binding site in the human platelet. alpha. sub 2 -adrenergic receptor

    SciTech Connect

    Matsui, Hiroaki; Lefkowitz, R.J.; Caron, M.G.; Regan, J.W. )

    1989-05-02

    The human platelet {alpha}{sub 2}-adrenergic receptor is an integral membrane protein which binds epinephrine. The gene for this receptor has been cloned, and the primary structure is thus known. A model of its secondary structure predicts that the receptor has seven transmembrane spanning domains. By covalent labeling and peptide mapping, the authors have identified a region of the receptor that is directly involved with ligand binding. Partially purified preparations of the receptor were covalently radiolabeled with either of two specific photoaffinity ligands: ({sup 3}H)SKF 102229 (an antagonist) or p-azido({sup 3}H)clonidine (an agonist). The radiolabeled receptors were then digested with specific endopeptidases, and peptides containing the covalently bound radioligands were identified. Lysylendopeptidase treatment of ({sup 3}H)SKF 102229 labeled receptor yielded one peptide of M{sub r} 2400 as the product of a complete digest. Endopeptidase Arg-C gave a labeled peptide of M{sub r} 4000, which was further digested to the M{sub r} 2400 peptide by additional treatment with lysylendopeptidase. Using p-azido({sup 3}H)clonidine-labeled receptor, a similar M{sub r} 2400 peptide was obtained by lysylendopeptidase cleavage. This M{sub r} 2400 peptide corresponds to the fourth transmembrane spanning domain of the receptor. These data suggest that this region forms part of the ligand binding domain of the human platelet {alpha}{sub 2}-adrenergic receptor.

  15. Role of descending noradrenergic system and spinal alpha2-adrenergic receptors in the effects of gabapentin on thermal and mechanical nociception after partial nerve injury in the mouse.

    PubMed

    Tanabe, Mitsuo; Takasu, Keiko; Kasuya, Noriyo; Shimizu, Shinobu; Honda, Motoko; Ono, Hideki

    2005-03-01

    1. To gain further insight into the mechanisms underlying the antihyperalgesic and antiallodynic actions of gabapentin, a chronic pain model was prepared by partially ligating the sciatic nerve in mice. The mice then received systemic or local injections of gabapentin combined with either central noradrenaline (NA) depletion by 6-hydroxydopamine (6-OHDA) or alpha-adrenergic receptor blockade. 2. Intraperitoneally (i.p.) administered gabapentin produced antihyperalgesic and antiallodynic effects that were manifested by elevation of the withdrawal threshold to a thermal (plantar test) or mechanical (von Frey test) stimulus, respectively. 3. Similar effects were obtained in both the plantar and von Frey tests when gabapentin was injected intracerebroventricularly (i.c.v.) or intrathecally (i.t.), suggesting that it acts at both supraspinal and spinal loci. This novel supraspinal analgesic action of gabapentin was only obtained in ligated neuropathic mice, and gabapentin (i.p. and i.c.v.) did not affect acute thermal and mechanical nociception. 4. In mice in which central NA levels were depleted by 6-OHDA, the antihyperalgesic and antiallodynic effects of i.p. and i.c.v. gabapentin were strongly suppressed. 5. The antihyperalgesic and antiallodynic effects of systemic gabapentin were reduced by both systemic and i.t. administration of yohimbine, an alpha2-adrenergic receptor antagonist. By contrast, prazosin (i.p. or i.t.), an alpha1-adrenergic receptor antagonist, did not alter the effects of gabapentin. 6. It was concluded that the antihyperalgesic and antiallodynic effects of gabapentin are mediated substantially by the descending noradrenergic system, resulting in the activation of spinal alpha2-adrenergic receptors.

  16. Dissociation of β1- and β2-adrenergic receptor subtypes in the retrieval of cocaine-associated memory.

    PubMed

    Fitzgerald, Michael K; Otis, James M; Mueller, Devin

    2016-01-01

    Drug seeking is maintained by encounters with drug-associated cues, and disrupting retrieval of these drug-cue associations would reduce the risk of relapse. Retrieval of cocaine-associated memories is dependent on β-adrenergic receptor (β-AR) activation, and blockade of these receptors induces a persistent retrieval deficit. Whether retrieval of cocaine-associated memory is mediated by a specific β-AR subtype, however, remains unclear. Using a cocaine conditioned place preference (CPP) procedure, we examined whether retrieval of a cocaine CPP memory is mediated collectively by β1- and β2-ARs, or by one of these β-AR subtypes alone. We show that co-blockade of β1- and β2-ARs abolished CPP expression on that and subsequent drug-free CPP tests, resulting in a long-lasting retrieval deficit that prevented subsequent cocaine-induced reinstatement. To dissociate the necessity of either β1- or β2-ARs alone, we administered subtype-specific antagonists prior to retrieval. Administration of a β1-AR antagonist before the initial CPP trial dose-dependently reduced expression of a CPP on that and subsequent drug-free trials as compared to vehicle administration. In contrast, administration of a β2-AR antagonist had no effect on initial CPP expression, although the highest dose reduced subsequent CPP expression. Importantly, either β1- or β2-AR blockade prior to an initial retrieval trial prevented subsequent cocaine-induced reinstatement. Our findings indicate that the β1-AR subtype mediates retrieval of a cocaine CPP, and that acutely blocking either β1- or β2-ARs can prevent subsequent cocaine-induced reinstatement. Thus, β-AR antagonists, particularly β1-ARs antagonists, could serve as adjuncts for addiction therapies to prevent retrieval of drug-associated memories and provide protection against relapse.

  17. Epinephrine administration increases neural impulses propagated along the vagus nerve: Role of peripheral beta-adrenergic receptors.

    PubMed

    Miyashita, T; Williams, C L

    2006-03-01

    A significant number of animal and human studies demonstrate that memories for new experiences are encoded more effectively under environmental or laboratory conditions which elevate peripheral concentrations of the hormone epinephrine and in turn, induce emotional arousal. Although this phenomenon has been replicated across several learning paradigms, understanding of how this arousal related hormone affects memory processing remains obscure because epinephrine does not freely enter into the central circulation to produce any direct effects on the brain. This study examined whether epinephrine's actions on the CNS may be mediated by the initial activation of peripheral vagal fibers that project to the brain. The vagus was selected as a candidate for this role since it is densely embedded with beta-adrenergic receptors and the peripheral endings of this nerve innervate a broad spectrum of sensory organs that are directly affected by epinephrine release. Electrophysiological recordings of cervical vagal activity was measured over 110 min in urethane-anesthetized Sprague-Dawley rats given saline, epinephrine (0.3 mg/kg), the peripherally acting beta-adrenergic antagonist sotalol (2.0 mg/kg), or a combination of sotalol followed 15 min later by an injection of epinephrine. Epinephrine produced a significant increase in vagal nerve firing 10 min post-injection (p < .05) relative to controls and neural impulses recorded from the vagus remained significantly elevated for the remaining 55 min collection period. The excitatory actions of epinephrine were not observed in groups given an identical dose of the hormone after peripheral beta-adrenergic receptor blockade with sotalol. These findings demonstrate that neural discharge in vagal afferent fibers is increased by elevations in peripheral concentrations of epinephrine and the significance of these findings in understanding how epinephrine modulates brain limbic structures to encode and store new information into memory

  18. 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.

  19. Real-time optical recording of β1-adrenergic receptor activation reveals supersensitivity of the Arg389 variant to carvedilol

    PubMed Central

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

    2007-01-01

    Antagonists of β-adrenergic receptors (β-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 β1-AR and downstream signaling. While the commonly used β-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 β1-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 β1-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 β1-AR in living cells in real time. It revealed that β1-AR variants dramatically differ in their responses to diverse beta blockers, with possible consequences for their clinical use. PMID:17200720

  20. α2 adrenergic receptor dysregulation in depressive disorders: implications for the neurobiology of depression and antidepressant therapy

    PubMed Central

    Cottingham, Christopher; Wang, Qin

    2012-01-01

    Dysfunction in noradrenergic neurotransmission has long been theorized to occur in depressive disorders. The α2 adrenergic receptor (AR) family, as a group of key players in regulating the noradrenergic system, has been investigated for involvement in the neurobiology of depression and mechanisms of antidepressant therapies. However, a clear picture of the α2ARs in depressive disorders has not been established due to the existence of apparently conflicting findings in the literature. In this article, we report that a careful accounting of methodological differences within the literature can resolve the present lack of consensus on involvement of α2ARs in depression. In particular, the pharmacological properties of the radioligand (e.g. agonist versus antagonist) utilized for determining receptor density are crucial in determining study outcome. Upregulation of α2AR density detected by radiolabeled agonists but not by antagonists in patients with depressive disorders suggests a selective increase in the density of high-affinity conformational state α2ARs, which is indicative of enhanced G protein coupling to the receptor. Importantly, this high-affinity state α2AR upregulation can be normalized with antidepressant treatments. Thus, depressive disorders appear to be associated with increased α2AR sensitivity and responsiveness, which may represent a physiological basis for the putative noradrenergic dysfunction in depressive disorders. In addition, we review changes in some key α2AR accessory proteins in depressive disorders and discuss their potential contribution to α2AR dysfunction. PMID:22910678

  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. Identification of beta-adrenergic receptors on cultured human fibroblast IMR-90 cells

    SciTech Connect

    Scarpace, P.J.

    1986-03-05

    Fibroblast cultures derived from normal human tissue undergo a finite number of population doublings when serial subcultivated in vitro. IMR-90 cells derived from human embryonic lung tissue undergo approximately 60 population doublings. Beta-adrenergic receptor (BAR) characteristics and isoproterenol-stimulated adenylate cyclase activity were assessed in IMR-90 cells at various population doublings (PDL). Scatchard analysis of /sup 125/I-Iodocyanopindolol (ICYP) binding yields a straight line consistent with a single class of antagonist binding sites with 452 +/- 35 sites/cell and a dissociation constant of 18.7 +/- 1.3 pM. There were no changes in BAR density between PDL 32 to PDL 46. Binding was both stereospecific and specific. Competition with epinephrine was 7.4 times more potent than with norepinephrine, suggesting predominate beta/sub 2/-type BAR. Competition with isoproterenol (Hill plots) indicated an apparent K/sub d/ of 1.3 +/- 0.1 x 10/sup -8/ M. Competition curves were resolved into high and low affinity binding sites yielding K/sub d/-high = 3.6 +/- 1.3 nM and k/sub d/-low = 1.6 +/- 0.7 x 10/sup -7/ M with 49.9 +/- 6.6% of the receptors in the high affinity state at PDL 31 to PDL 37. Cultures demonstrate isoproterenol-stimulated adenylate cyclase activity with a concentration of 1 x 10/sup -6/ M producing half-maximal stimulation and a maximum stimulation of 2 pmol cAMP/mg/min. Forskolin-stimulated was 10 pmol/cAMP/mg/min at PDL 46.

  3. 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

  4. 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.

  5. [Sleep disturbances in Smith-Magenis syndrome: treatment with melatonin and beta-adrenergic antagonists].

    PubMed

    Van Thillo, A; Devriendt, K; Willekens, D

    2010-01-01

    Smith-Magenis syndrome is a generic disorder, characterised by physical, neurological and behavioural features and caused by a 17p11.2 deletion. Patients with this syndrome typically display an inversion of the sleep-wake cycle. In this article we describe clinical developments in a two-year-old girl with Smith-Magenis syndrome whose sleep problems were successfully treated with melatonin and beta-adrenergic blockers. We also mention relevant data obtained in our literature search.

  6. Properties of rat erythrocyte membrane cytoskeletal structures produced by digitonin extraction: digitonin-insoluble beta-adrenergic receptor, adenylate cyclase, and cholera toxin substrate.

    PubMed

    LeVine, H; Sahyoun, N E; Cuatrecasas, P

    1982-01-01

    Rat erythrocyte plasma membranes have been extracted exhaustively with digitonin at low temperature, and the residual, detergent-extracted membrane cytoskeletal material is compared to that prepared with Triton X-100 with respect to protein, glycoprotein, phospholipid, and cholesterol content. Digitonin, a weaker detergent than Triton X-100, solubilizes only 26% of the phospholipids and none of the cholesterol. SDS-polyacrylamide gel electrophoresis reveals that differences between the proteins extracted by the two detergents are primarily quantitative. In terms of functional preservation, digitonin retains in the cytoskeleton 28% of the beta-adrenergic receptor binding activity (with the balance accounted for in the supernatant), greater than 90% of the adenylate cyclase and greater than 90% of the 45,000 mol wt polypeptide cholera toxin substrate. The cytoskeletal-associated beat-adrenergic receptor retains binding properties for antagonist and agonist which are identical to those of the native membrane receptor. The digitonin-extracted cytoskeleton containing the beta-adrenergic receptor may provide a useful vehicle for the reconstitution of a hormone-sensitive adenylate cyclase.

  7. 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.

  8. 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

  9. Cholesterol modulates the dimer interface of the β₂-adrenergic receptor via cholesterol occupancy sites.

    PubMed

    Prasanna, Xavier; Chattopadhyay, Amitabha; Sengupta, Durba

    2014-03-18

    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.

  10. Discovery of Novel Triazole-Based Opioid Receptor Antagonists

    PubMed Central

    Zhang, Qiang; Keenan, Susan M.; Peng, Youyi; Nair, Anil C.; Yu, Seong Jae; Howells, Richard D.; Welsh, William J.

    2009-01-01

    We report the computer-aided design, chemical synthesis, and biological evaluation of a novel family of δ opioid receptor (DOR) antagonists containing a 1,2,4-triazole core structure that are structurally distinct from other known opioid receptor active ligands. Among those δ antagonists sharing this core structure, 8 exhibited strong binding affinity (Ki = 50 nM) for the DOR and appreciable selectivity for δ over μ and opioid receptors (δ/μ = 80; δ/κ > 200). PMID:16821764

  11. Molecular Modeling Study of Chiral Separation and Recognition Mechanism of β-Adrenergic Antagonists by Capillary Electrophoresis

    PubMed Central

    Li, Wuhong; Liu, Changhai; Tan, Guangguo; Zhang, Xinrong; Zhu, Zhenyu; Chai, Yifeng

    2012-01-01

    Chiral separations of five β-adrenergic antagonists (propranolol, esmolol, atenolol, metoprolol, and bisoprolol) were studied by capillary electrophoresis using six cyclodextrins (CDs) as the chiral selectors. Carboxymethylated-β-cyclodextrin (CM-β-CD) exhibited a higher enantioselectivity power compared to the other tested CDs. The influences of the concentration of CM-β-CD, buffer pH, buffer concentration, temperature, and applied voltage were investigated. The good chiral separation of five β-adrenergic antagonists was achieved using 50 mM Tris buffer at pH 4.0 containing 8 mM CM-β-CD with an applied voltage of 24 kV at 20 °C. In order to understand possible chiral recognition mechanisms of these racemates with CM-β-CD, host-guest binding procedures of CM-β-CD and these racemates were studied using the molecular docking software Autodock. The binding free energy was calculated using the Autodock semi-empirical binding free energy function. The results showed that the phenyl or naphthyl ring inserted in the hydrophobic cavity of CM-β-CD and the side chain was found to point out of the cyclodextrin rim. Hydrogen bonding between CM-β-CD and these racemates played an important role in the process of enantionseparation and a model of the hydrogen bonding interaction positions was constructed. The difference in hydrogen bonding formed with the –OH next to the chiral center of the analytes may help to increase chiral discrimination and gave rise to a bigger separation factor. In addition, the longer side chain in the hydrophobic phenyl ring of the enantiomer was not beneficial for enantioseparation and the chiral selectivity factor was found to correspond to the difference in binding free energy. PMID:22312281

  12. Cloning, sequencing, and expression of the gene coding for the human platelet. cap alpha. /sub 2/-adrenergic receptor

    SciTech Connect

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

    1987-10-30

    The gene for the human platelet ..cap alpha../sub 2/-adrenergic receptor has been cloned with oligonucleotides corresponding to the partial amino acid sequence of the purified receptor. The identity of this gene has been confirmed by the binding of ..cap alpha../sub 2/-adrenergic ligands to the cloned receptor expressed in Xenopus laevis oocytes. The deduced amino acid sequence is most similar to the recently cloned human ..beta../sub 2/- and ..beta../sub 1/-adrenergic receptors; however, similarities to the muscarinic cholinergic receptors are also evident. Two related genes have been identified by low stringency Southern blot analysis. These genes may represent additional ..cap alpha../sub 2/-adrenergic receptor subtypes.

  13. 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

  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. Central Adrenergic Receptors as Mediators of Central Response to Stress: Study with Positron Emission Tomography (PET).

    DTIC Science & Technology

    1988-02-19

    radiolabeled precursor, we chose to produce C- I I-N-methylspiperone (NMS), a ligand of dopamine D2 receptors . This molecule was selected since its...which approximate a situation of stress. Second, development of tracer molecules for in vivo analyses of beta-adrenergic receptors . Interesting data... non metabolized glucose analog, is injected intraveinously into a forearm vein. The tracer input function is sampled from a catheter inserted into a

  16. CGS 8216: receptor binding characteristics of a potent benzodiazepine antagonist.

    PubMed

    Czernik, A J; Petrack, B; Kalinsky, H J; Psychoyos, S; Cash, W D; Tsai, C; Rinehart, R K; Granat, F R; Lovell, R A; Brundish, D E; Wade, R

    1982-01-25

    CGS 8216 is a novel nonbenzodiazepine that inhibited 3H-flunitrazepam (3H-FLU) binding to rat synaptosomal membranes in vitro at subnanomolar concentrations. It prevented the in vivo labeling of brain benzodiazepine receptors by 3H-FLU with the same potency as diazepam when given orally to mice. Pharmacologic tests showed that it was devoid of benzodiazepine-like activity but it antagonized the actions of diazepam in these tests. It did not interact with alpha- or beta- adrenergic, H1-histaminergic or GABA receptors but it inhibited adenosine-activation of cyclic AMP formation. Studies with 3H-CGS 8216 demonstrated that it bound specifically and with high affinity to rat forebrain membranes and was displaced by drugs with an order of potencies similar to that observed when 3H-diazepam and 3H-FLU were used as radioligands. The regional distribution of 3H-CGS 8216 binding sites in the brain was also similar to that of 3H-FLU. Dissociation of 3H-CGS 8216 binding was slow at 0 degrees C but increased with temperature and was almost complete within 1 min at 37 degrees C. Scatchard analyses were linear, yielding KD values of 0.044, 0.11 and 0.18 nM at 0, 25 and 37 degrees C, respectively; the Bmax value did not change appreciably with temperature and was approximately 1000 fmoles/mg protein. Using 3H-FLU, the value for Bmax as well as for the KD increased with temperature. The total number of binding sites determined for 3H-FLU was greater than that for 3H-CGS 8216 at each temperature. CGS 8216 exhibited mixed-type inhibition of 3H-FLU binding. GABA did not stimulate 3H-CGS 8216 binding whereas it enhanced 3H-FLU binding. CGS 8216 may be a useful ligand for probing the antagonist properties of the benzodiazepine receptor and is likely to exhibit interesting therapeutic effects.

  17. High‐fat diet induces protein kinase A and G‐protein receptor kinase phosphorylation of β2‐adrenergic receptor and impairs cardiac adrenergic reserve in animal hearts

    PubMed Central

    Hu, Yuting; Wang, Qingtong; Liu, Yongming; Li, Ning; Xu, Bing; Kim, Sungjin; Chiamvimonvat, Nipavan

    2017-01-01

    Key points Patients with diabetes show a blunted cardiac inotropic response to β‐adrenergic stimulation despite normal cardiac contractile reserve.Acute insulin stimulation impairs β‐adrenergically induced contractile function in isolated cardiomyocytes and Langendorff‐perfused hearts.In this study, we aimed to examine the potential effects of hyperinsulinaemia associated with high‐fat diet (HFD) feeding on the cardiac β2‐adrenergic receptor signalling and the impacts on cardiac contractile function.We showed that 8 weeks of HFD feeding leads to reductions in cardiac functional reserve in response to β‐adrenergic stimulation without significant alteration of cardiac structure and function, which is associated with significant changes in β2‐adrenergic receptor phosphorylation at protein kinase A and G‐protein receptor kinase sites in the myocardium.The results suggest that clinical intervention might be applied to subjects in early diabetes without cardiac symptoms to prevent further cardiac complications. Abstract Patients with diabetes display reduced exercise capability and impaired cardiac contractile reserve in response to adrenergic stimulation. We have recently uncovered an insulin receptor and adrenergic receptor signal network in the heart. The aim of this study was to understand the impacts of high‐fat diet (HFD) on the insulin–adrenergic receptor signal network in hearts. After 8 weeks of HFD feeding, mice exhibited diabetes, with elevated insulin and glucose concentrations associated with body weight gain. Mice fed an HFD had normal cardiac structure and function. However, the HFD‐fed mice displayed a significant elevation of phosphorylation of the β2‐adrenergic receptor (β2AR) at both the protein kinase A site serine 261/262 and the G‐protein‐coupled receptor kinase site serine 355/356 and impaired adrenergic reserve when compared with mice fed on normal chow. Isolated myocytes from HFD‐fed mice also displayed a

  18. Muscarinic cholinergic and alpha/sub 1/ adrenergic receptors in murine atria: phosphatidylinositol breakdown and receptor interaction

    SciTech Connect

    Scherer, R.W.

    1987-01-01

    Upon stimulation of muscarinic cholinergic receptors, there is a decrease in the force of contraction rate of firing in heart, while stimulation of ..cap alpha.. adrenergic receptors causes an increase in the force of contraction with no change in the heart rate. Yet both receptors stimulate the breakdown of phosphatidylinositol (PI). Therefore, the breakdown of PI was examined to determine how the process differed between the two receptor systems. Murine atria, prelabelled with (/sup 3/H)inositol, were stimulated with the muscarinic cholinergic agonists, carbamylcholine (CARB), and oxotremorine (OXO); and with the ..cap alpha.. adrenergic agonists, norepinephrine (NE) and phenylephrine (PE); either singly or in combination. Breakdown of PI was assessed by measurement of individual inositol phosphates by anion exchange chromatography. Binding of CARB to atrial muscarinic receptors was measured by competition with (/sup 3/H)quinuclidinyl benzilate.

  19. The receptor kinase family: primary structure of rhodopsin kinase reveals similarities to the beta-adrenergic receptor kinase.

    PubMed Central

    Lorenz, W; Inglese, J; Palczewski, K; Onorato, J J; Caron, M G; Lefkowitz, R J

    1991-01-01

    Light-dependent deactivation of rhodopsin as well as homologous desensitization of beta-adrenergic receptors involves receptor phosphorylation that is mediated by the highly specific protein kinases rhodopsin kinase (RK) and beta-adrenergic receptor kinase (beta ARK), respectively. We report here the cloning of a complementary DNA for RK. The deduced amino acid sequence shows a high degree of homology to beta ARK. In a phylogenetic tree constructed by comparing the catalytic domains of several protein kinases, RK and beta ARK are located on a branch close to, but separate from the cyclic nucleotide-dependent protein kinase and protein kinase C subfamilies. From the common structural features we conclude that both RK and beta ARK are members of a newly delineated gene family of guanine nucleotide-binding protein (G protein)-coupled receptor kinases that may function in diverse pathways to regulate the function of such receptors. Images PMID:1656454

  20. Astrocytic β2 Adrenergic Receptor Gene Deletion Affects Memory in Aged Mice

    PubMed Central

    Jensen, Cathy Joanna; Demol, Frauke; Bauwens, Romy; Kooijman, Ron; Massie, Ann; Villers, Agnès; Ris, Laurence; De Keyser, Jacques

    2016-01-01

    In vitro and in vivo studies suggest that the astrocytic adrenergic signalling enhances glycogenolysis which provides energy to be transported to nearby cells and in the form of lactate. This energy source is important for motor and cognitive functioning. While it is suspected that the β2-adrenergic receptor on astrocytes might contribute to this energy balance, it has not yet been shown conclusively in vivo. Inducible astrocyte specific β2-adrenergic receptor knock-out mice were generated by crossing homozygous β2-adrenergic receptor floxed mice (Adrb2flox) and mice with heterozygous tamoxifen-inducible Cre recombinase-expression driven by the astrocyte specific L-glutamate/L-aspartate transporter promoter (GLAST-CreERT2). Assessments using the modified SHIRPA (SmithKline/Harwell/Imperial College/Royal Hospital/Phenotype Assessment) test battery, swimming ability test, and accelerating rotarod test, performed at 1, 2 and 4 weeks, 6 and 12 months after tamoxifen (or vehicle) administration did not reveal any differences in physical health or motor functions between the knock-out mice and controls. However deficits were found in the cognitive ability of aged, but not young adult mice, reflected in impaired learning in the Morris Water Maze. Similarly, long-term potentiation (LTP) was impaired in hippocampal brain slices of aged knock-out mice maintained in low glucose media. Using microdialysis in cerebellar white matter we found no significant differences in extracellular lactate or glucose between the young adult knock-out mice and controls, although trends were detected. Our results suggest that β2-adrenergic receptor expression on astrocytes in mice may be important for maintaining cognitive health at advanced age, but is dispensable for motor function. PMID:27776147

  1. 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.

  2. 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.

  3. Identification of the Cardiac Beta-Adrenergic Receptor Protein: Solubilization and Purification by Affinity Chromatography

    PubMed Central

    Lefkowitz, Robert J.; Haber, Edgar; O'Hara, Donald

    1972-01-01

    A protein that binds catecholamines with a specificity parallel to that of their in vivo effects on cardiac contractility (isoproterenol > epinephrine or norepinephrine > dopamine > dihydroxyphenylalanine) was solubilized from a microsomal fraction of canine ventricular myocardium. The binding protein was purified 500 to 800-fold by solubilization and subsequent affinity chromatography with conjugates of norepinephrine linked to agarose beads. Purified β-adrenergic binding protein exists in two forms, corresponding to molecular weights of 40,000 and 160,000. The purified material has a single association constant, 2.3 × 105 liters/mol (as compared to two association constants, 107 and 106 liters/mol, for the binding protein in particulate form) but retains the identical binding specificity for β-adrenergic drugs and antagonists. Images PMID:4507606

  4. 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

  5. Phorbol esters inhibit alpha/sub 1/-adrenergic receptor stimulated phosphoinositide hydrolysis and contraction in rat aorta

    SciTech Connect

    Not Available

    1986-03-01

    The mechanisms of pharmacomechanical coupling in vascular tissue are at the present time unclear. The authors and others have proposed that receptor-induced activation of phosphoinositide (PI) hydrolysis may be involved. To investigate this possibility they studied the actions of two biologically active phorbol esters: phorbol dibutyrate (PDB) and phorbol myristate diacetate (PMA) on receptor-stimulated PI hydrolysis in rat aortic rings. They found both PDB (IC/sub 5//sup 0/ approx. 5nM) and PMA (IC/sub 50/ approx. 30 nM) but not 4-..cap alpha..-phorbol (IC32%/sub 0/ > 10,000 nM) inhibited norepinephrine-stimulated PI hydrolysis. In the presence of the calcium channel antagonist nitrendipine, PDB potently inhibited both the phasic and tonic components of norepinephrine-induced vascular contraction. In the presence of 10/sup -7/M nitrendipine, PDB had an IC/sub 50/ for contraction of approximately 10nM. The results thus suggest a functional coupling between ..cap alpha../sub 1/-adrenergic receptor-stimulated PI hydrolysis and vascular contraction. The findings further imply a mode of feed-back regulation in vascular tissue involving phorbol ester and receptor-stimulated PI hydrolysis.

  6. GABAA receptor-mediated stimulation of non-adrenergic non-cholinergic neurones in the dog ileocolonic junction.

    PubMed

    Boeckxstaens, G E; Pelckmans, P A; Rampart, M; Ruytjens, I F; Verbeuren, T J; Herman, A G; Van Maercke, Y M

    1990-10-01

    1. The inhibitory effects of gamma-aminobutyric acid (GABA), the GABAA receptor agonist homotaurine and the GABAB receptor agonist (+/-)-baclofen were investigated on circular muscle strips of the dog terminal ileum and ileocolonic junction. 2. In the presence of atropine, GABA and homotaurine induced concentration-dependent relaxations, similar to the non-adrenergic non-cholinergic (NANC)-mediated relaxations evoked by electrical stimulation or by acetylcholine. The ileocolonic junction was more sensitive to GABA and homotaurine than the ileum. (+/-)-Baclofen had no effect. Cross desensitization only occurred between GABA and homotaurine. 3. The GABAA receptor antagonist bicuculline shifted the concentration-response curves to GABA and homotaurine to the right. The maximal relaxation to GABA remained unaffected. 4. GABA-induced relaxations were not inhibited by timolol, guanethidine, domperidone, hexamethonium and desensitization to ATP, but were abolished by tetrodotoxin. 5. Bicuculline, and pretreatment with GABA or (+/-)-baclofen had no effect on the NANC-evoked relaxations to electrical stimulation and acetylcholine. 6. In conclusion, GABA stimulates GABAA receptors located on inhibitory NANC neurones in the dog ileocolonic junction. Our results suggest that it is unlikely that GABA is the final inhibitory NANC neurotransmitter.

  7. Noradrenaline Improves Behavioral Contrast Sensitivity via the β-Adrenergic Receptor

    PubMed Central

    Mizuyama, Ryo; Soma, Shogo; Suemastu, Naofumi; Shimegi, Satoshi

    2016-01-01

    Noradrenaline (NA) is released from the locus coeruleus in the brainstem to almost the whole brain depending on the physiological state or behavioral context. NA modulates various brain functions including vision, but many questions about the functional role of its effects and mechanisms remain unclear. To explore these matters, we focused on three questions, 1) whether NA improves detectability of a behavior-relevant visual stimulus, 2) which receptor subtypes contribute to the NA effects, and 3) whether the NA effects are specific for visual features such as spatial frequency (SF). We measured contrast sensitivity in rats by a two-alternative forced choice visual detection task and tested the effects of NA receptor blockers in three SF conditions. Propranolol, a β-adrenergic receptor inhibitor, significantly decreased contrast sensitivity, but neither prazosin nor idazoxan, α1- and α2-adrenergic receptor inhibitors, respectively, had an effect. This β blocker effect was observed only at optimal SF. These results indicate that endogenous NA enhances visual detectability depending on stimulus spatial properties via mainly β-adrenergic receptors. PMID:27992510

  8. Stimulation of an alpha1-adrenergic receptor downregulates ecto-5' nucleotidase activity on the apical membrane of RPE cells.

    PubMed

    Reigada, David; Zhang, Xiulan; Crespo, Ana; Nguyen, Johnathan; Liu, Ji; Pendrak, Klara; Stone, Richard A; Laties, Alan M; Mitchell, Claire

    2006-09-01

    The purines ATP and adenosine play an important role in the communication between the photoreceptors and the retinal pigment epithelium (RPE). While the RPE is known to release ATP into subretinal space, the source of extracellular adenosine is unclear. In other tissues, ecto-nucleotidases mediate the consecutive dephosphorylation of ATP to AMP, and AMP is converted to adenosine by ecto-5' nucleotidase (CD73). This study identifies ecto-5' nucleotidase on RPE cells and investigates modulation of enzyme activity. The RPE was the most active site of 5'AMP dephosphorylation in the posterior rat eye. The ecto-5' nucleotidase inhibitor alphabetamADP prevented the production adenosine by the apical membrane of the bovine RPE. Cultured human ARPE-19 cells expressed mRNA and protein for ecto-5' nucleotidase. The production of phosphate from 5'AMP by ARPE-19 cells was inhibited by alphabetamADP, but the ecto-alkaline phosphatase inhibitor levamisole had no effect. Degradation of 5'AMP was blocked by norepinephrine, epinephrine and phenylephrine, with inhibition by antagonists prazosin and corynanthine implicating the alpha1 adrenergic receptor. The block of enzyme activity by norepinephrine was rapid, occurring within 1 min, and was similar at both 4 and 37 degrees C, consistent with cleavage of the enzyme from its GPI anchor. HPLC measurements indicated norepinephrine reduced levels of adenosine in the bath. In the apical face of the bovine-RPE eyecup, norepinephrine reduced the production of phosphate from 5'AMP, suggesting that both receptor and enzyme face sub-retinal space. In conclusion, RPE cells express ecto-5' nucleotidase, with activity on the apical membrane, and stimulation of alpha-1 adrenergic receptors downregulates activity. As epinephrine is released at light onset, and adenosine can inhibit phagocytosis, the corresponding decrease in subretinal adenosine levels may contribute to the enhanced the phagocytosis of rod outer segments that occurs at this time.

  9. CXCR2 receptor antagonists: a medicinal chemistry perspective.

    PubMed

    Dwyer, Michael P; Yu, Younong

    2014-01-01

    Dysregulated leukocyte recruitment is believed to be a key contributor to various acute and chronic inflammatory disorders which can lead to serious pathological consequences. Chemokines are small molecular weight proteins that have been shown to be imperative in the direction of leukocytes to the sites of inflammation. In humans, several of these chemokines (CXCL8 and CXCL1) are elevated in inflammatory disorders such as asthma, arthritis, and chronic obstructive pulmonary disease (COPD). These chemokines modulate their downstream effects thru G-protein coupled receptors, such as CXCR2, making the identification of small-molecule antagonists of this receptor attractive towards developing novel therapies to treat inflammatory conditions. Since the first report of a CXCR2 receptor antagonist in 1998, there has been a considerable effort conducted mainly in the pharmaceutical industry to identify novel classes of CXCR2 receptor antagonists. Over a dozen distinct classes of CXCR2 receptor antagonists have been reported in the literature to date with a number of these compounds having reached mid-stage clinical trials. This review will provide a broad overview the medicinal chemistry efforts over the past 15 years towards the identification of CXCR2 receptor antagonists. The discussion will focus upon the early preclinical space covering the structure activity relationships (SAR), pharmacology, as well in preclinical in vivo evaluation for the different series of CXCR2 receptor antagonists. In addition, the available clinical data for the most advanced compounds in the clinic will be discussed and along with a perspective of the area moving forward.

  10. 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.

  11. Alpha-adrenergic receptor blockade by phentolamine increases the efficacy of vasodilators in penile corpus cavernosum.

    PubMed

    Kim, N N; Goldstein, I; Moreland, R B; Traish, A M

    2000-03-01

    Penile trabecular smooth muscle tone, a major determinant of erectile function, is highly regulated by numerous inter- and intracellular pathways. The interaction between pathways mediating contraction and relaxation has not been studied in detail. To this end, we investigated the functional effects of alpha adrenergic receptor blockade with phentolamine and its interaction with vasodilators (sildenafil, vasoactive intestinal polypeptide (VIP) and PGE1) that elevate cyclic nucleotides on penile cavernosal smooth muscle contractility. In organ bath preparations of cavernosal tissue strips contracted with phenylephrine, phentolamine significantly enhanced relaxation induced by sildenafil, VIP and PGE1. Sildenafil, VIP or PGE1 also significantly enhanced relaxation induced by phentolamine in cavernosal tissue strips contracted with phenylephrine. To study the effects of alpha adrenergic receptor blockade and modification of cyclic nucleotide metabolism during active neurogenic input, cavernosal tissue strips in organ bath preparations were contracted with the non-adrenergic agonist endothelin-1 and subjected to electrical field stimulation (EFS) in the absence or presence of phentolamine and/or sildenafil. EFS (5-40Hz) typically caused biphasic relaxation and contraction responses. Phentolamine alone enhanced relaxation and reduced or prevented contraction to EFS. Sildenafil enhanced relaxation to EFS at lower frequencies (< or = 5 Hz). The combination of phentolamine and sildenafil enhanced EFS-induced relaxation at all frequencies tested. EFS, in the presence of 10 nM phentolamine and 30 nM sildenafil, produced enhanced relaxation responses which were quantitatively similar to those obtained in the presence of 50 nM sildenafil alone. Thus, blockade of alpha-adrenergic receptors with phentolamine increases the efficacy of cyclic nucleotide-dependent vasodilators. Furthermore, phentolamine potentiates relaxation and attenuates contraction in response to endogenous

  12. Vasopressin-receptor antagonist therapy in patients with hyponatraemia.

    PubMed

    Vachharajani, Tushar; Vachharajani, Vidula

    2007-07-01

    Hyponatraemia often complicates the treatment of underlying conditions in patients who are seriously ill. Arginine vasopressin receptor antagonists block the action of arginine vasopressin and correct sodium and water imbalance in patients with euvolaemic or hypervolaemic hyponatraemia.

  13. Butyrate modulates the expression of. beta. -adrenergic receptor subtype in 3T3-L1 cells

    SciTech Connect

    Poksay, K.S.; Nakada, M.T.; Crooke, S.T.; Stadel, J.M.

    1986-03-05

    In mouse 3T3-L1 fibroblasts, the glucocorticoid dexamethasone (dex) affects a switch in ..beta..-adrenergic receptor (..beta..AR) subtype expression from ..beta../sub 1/AR to ..beta../sub 2/AR and increases total ..beta..AR number. They now demonstrate a similar effect by sodium butyrate (B) and find that the combined effect of these two gene-activating agents is greater than additive suggesting different mechanisms of action on the ..beta..AR. ..beta..AR are assayed in membranes prepared from 3T3-L1 cells using the radiolabeled ..beta..AR-specific antagonist (/sup 125/I)-cyanopindolol. ..beta..AR subtype is determined by competition binding of the ..beta../sub 2/AR-selective antagonist ICI 118.551 for the radioligand. B (2-10mM) causes a dose-dependent increase in total ..beta..AR number (up to 2-fold over control) and the proportion of ..beta../sub 2/AR. B (5mM) causes a time-dependent increase in total ..beta..AR number (2-fold) and the proportion of ..beta../sub 2/AR up to 24 hr. Dex maximally increases total ..beta..AR number (2-fold) when treated for 48 hr at concentrations greater than or equal to 100nM. B (2 or 5mM) together with dex (250nM) have a greater than additive effect on total ..beta..AR number at 24 hr (1.7-fold) and at 48 hr (1.4-2.4-fold, using 5 or 10mM B and dex greater than or equal to 10nM). The proportion of ..beta../sub 2/AR is also greater when both compounds are added together. In comparison with proprionate and valerate, B increases total ..beta..AR number and the proportion of ..beta../sub 2/AR to a greater extent and at lower concentrations. To determine a functional correlate to these findings, cells were pre-treated for 48 hr with B and/or dex, intracellular ATP labeled with /sup 3/H-adenine, followed by treatment with forskolin (10..mu..M) and ..beta..AR agonists. B caused a dramatic increase in /sup 3/H-cAMP produced compared to control and dex treatments and a greater than additive effect was again achieved when B and dex were

  14. Isolation of rat genomic clones encoding subtypes of the alpha 2-adrenergic receptor. Identification of a unique receptor subtype.

    PubMed

    Lanier, S M; Downing, S; Duzic, E; Homcy, C J

    1991-06-05

    alpha 2-Adrenergic receptors (alpha 2-AR) exist as subtypes that are expressed in a tissue-specific manner and differ in 1) their ligand recognition properties, 2) their extent of receptor protein glycosylation, and possible 3) their mechanism of signal transduction. Genomic or cDNA clones encoding three receptor subtypes have been characterized; however, both functional and radioligand binding studies in rodents suggest the existence of a fourth receptor subtype. To isolate the rat genes encoding receptor subtypes we screened a rat genomic library with an oligonucleotide probe encompassing the third membrane span of the human C-4 alpha 2-AR. Two intronless rat genes were isolated that encode distinct receptor subtypes (RG10, RG20). RG10 and RG20 encode proteins of 458 and 450 amino acids, respectively, that are 56% homologous and possess the structural features expected of this class of membrane-bound receptors. RG10 identifies a mRNA species of approximately 2500 nucleotides that is found primarily in brain, whereas RG20 identifies a larger mRNA species (approximately 4000 nucleotides) that is found in several tissues including brain, kidney, and salivary gland. RG10 is 88% homologous to the human C-4 alpha 2-AR and exhibits similar binding properties ( [3H]rauwolscine KD = 0.7 +/- 0.3 nM) as determined following transient expression of the receptor in COS-1 cells. RG20 exhibits ligand binding properties distinct from the three receptor subtypes identified by molecular cloning. Saturation binding studies indicate an affinity constant of 15 +/- 1.2 nM for the alpha 2-AR antagonist [3H]rauwolscine, a value 6-20 times higher than that observed for the three cloned receptor subtypes. In competition binding studies the potency order of competing ligands for RG20 is phentolamine greater than idazoxan greater than yohimbine greater than rauwolscine greater than prazosin. Of the three previously cloned alpha 2-AR, RG20 is most closely related to the human C-10 alpha 2-AR

  15. 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.

  16. [Angiotensin II receptor antagonists: different or equivalent?].

    PubMed

    Mounier-Vehier, C; Devos, P

    ARA-II: Angiotensin II receptor antagonists (ARA-II) belong to a recent class of antihypertensive drugs whose mechanism of action is similar to converting enzyme inhibitors (CEI). ARA-II are particularly interesting due to the excellent clinical and biological tolerance, similar to placebo, and their antihypertensive efficacy, comparable with classical drug classes. PUBLISHED TRIALS: A meta-analysis, published by Conlin in the American Journal of Hypertension, suggests that ARA-II, specifically losartan, valsartan, irbesartan and candesartan, have an equipotent blood pressure lowering effect. The careful lecture of this meta-analysis however discloses a faulty methodology from which no valid conclusion can be drawn. Since this early publication, several other comparative studies have been published. These multicentric, randomized double-blind studies enrolled a sufficient number of patients and demonstrated a clinical difference between certain ARA-II at usual dosages. CLINICAL PRACTICE: These studies do have an impact on everyday practice. For the practitioner, the goal is to obtain and then maintain a long-term and optimal reduction in the blood pressure level (reduction or prevention of target-organ disorders and cardiovascular complications of high blood pressure). This reduction in the cardiovascular risk will also depend directly on tolerance and compliance to the antihypertensive treatment. This element must also be considered in assessing treatment efficacy, independent of the blood pressure lowering effect. The results of several other studies will be published in 2001-2003. These large-scale studies on ARA-II related morbidity and mortality will be most useful in determining the role of these drugs in different therapeutic strategies compared with other drug classes.

  17. Brain beta-adrenergic receptor binding in rats with obesity induced by a beef tallow diet.

    PubMed

    Matsuo, T; Suzuki, M

    1997-01-01

    We have previously reported that compared with safflower oil diet, feeding a beef tallow diet leads to a greater accumulation of body fat by reducing sympathetic activities. The present study examined the effects of dietary fats consisting of different fatty acids on alpha1- and beta-adrenergic receptor binding in the hypothalamus and cerebral cortex. Male Sprague-Dawley rats were meal-fed isoenergetic diets based on safflower oil (rich in n-6 polyunsaturated fatty acids) or beef tallow (rich in saturated fatty acids) for 8 weeks. Binding affinities of the beta-adrenergic receptor in the hypothalamus and cortex were significantly lower in the beef tallow diet group, but those of the alpha1-receptor did not differ between the two groups. The polyunsaturated to saturated fatty acid (P/S) ratio and fluidities of plasma membranes in the hypothalamus and cortex were lower in the beef tallow diet group than in the safflower oil diet group. These results suggest that the beef tallow diet decreases membrane fluidity by altering the fatty acid composition of plasma membranes in the hypothalamus and cerebral cortex of rat. Consequently, beta-adrenergic receptor binding affinities in the brain were lower in rats fed the beef tallow diet than in rats fed the safflower oil diet. We recognized that there is possible link between the membrane fluidity and the changes in affinity of beta-adrenoceptors in rat brain.

  18. The protein acyl transferase ZDHHC21 modulates α1 adrenergic receptor function and regulates hemodynamics

    PubMed Central

    Marin, Ethan P.; Jozsef, Levente; Di Lorenzo, Annarita; Held, Kara F.; Luciano, Amelia K.; Melendez, Jonathan; Milstone, Leonard M.; Velazquez, Heino; Sessa, William C.

    2016-01-01

    Objective Palmitoylation, the reversible addition of the lipid palmitate to a cysteine, can alter protein localization, stability, and function. The ZDHHC family of protein acyl transferases catalyzes palmitoylation of numerous proteins. The role of ZDHHC enzymes in intact tissue and in vivo is largely unknown. Herein, we characterize vascular functions in a mouse that expresses a nonfunctional ZDHHC21 (“F233Δ”). Approach and Results Physiological studies of isolated aortae and mesenteric arteries from F233Δ mice revealed an unexpected defect in responsiveness to phenylephrine, an α1 adrenergic receptor agonist. In vivo, F233Δ mice displayed a blunted response to infusion of phenylephrine and were found to have elevated catecholamine levels and elevated vascular α1 adrenergic receptor gene expression. Telemetry studies showed that the F233Δ mice were tachycardic and hypotensive at baseline, consistent with diminished vascular tone. In biochemical studies, ZDHHC21 was shown to palmitoylate the α1D adrenoceptor, and to interact with it in a molecular complex, thus suggesting a possible molecular mechanism by which the receptor can be regulated by ZDHHC21. Conclusions Together the data support a model in which ZDHHC21 F233Δ diminishes the function of vascular α1 adrenergic receptors, leading to reduced vascular tone which manifests in vivo as hypotension and tachycardia. This is to our knowledge the first demonstration of a ZDHHC isoform affecting vascular function in vivo and identifies a novel molecular mode of regulation of vascular tone and blood pressure. PMID:26715683

  19. A label-free optical biosensor with microfluidics identifies an intracellular signalling wave mediated through the β(2)-adrenergic receptor.

    PubMed

    Ferrie, Ann M; Wang, Chaoming; Deng, Huayun; Fang, Ye

    2013-10-01

    The canonical model of G protein-coupled receptor (GPCR) signalling states that it is solely initiated at the cell surface. In recent years, a handful of evidence has started emerging from high-resolution molecular assays that the internalized receptors can mediate the third wave of signalling, besides G protein- and β-arrestin-mediated signalling both initiating at the cell surface. However, little is known about the functional consequences of distinct waves of GPCR signalling, in particular, at the whole cell system level. We here report the development of label-free biosensor antagonist reverse assays and their use to differentiate the signalling waves of an endogenous β2-adrenergic receptor (β2-AR) in A431 cells. Results showed that the persistent agonist treatment activated the β2-ARs, leading to a long-term sustained dynamic mass redistribution (DMR) signal, a whole cell phenotypic response. Under the persistent treatment scheme in microplates, a panel of known β-blockers all dose-dependently and completely reversed the DMR signal of epinephrine at a relatively low dose (10 nM), except for sotalol which partially reversed the DMR. Under the perfusion conditions with microfluidics, the subsequent perfusion with sotalol only reversed the DMR induced by epinephrine or isoproterenol at 10 nM, but not at 10 μM. Furthermore, the degree of the DMR reversion by sotalol was found to be in an opposite relation with the duration of the initial agonist treatment. Together, these results suggest that the hydrophilic antagonist sotalol is constrained outside the cells throughout the assays, and the early signalling wave initiated at the cell surface dominates the DMR induced by epinephrine or isoproterenol at relatively low doses, while a secondary and late signalling wave is initiated once the receptors are internalized and contributes partially to the long-term sustainability of the DMR of epinephrine or isoproterenol at high doses.

  20. Cardiovascular effects of selective agonists and antagonists of histamine H3 receptors in the anaesthetized rat.

    PubMed

    Coruzzi, G; Gambarelli, E; Bertaccini, G; Timmerman, H

    1995-06-01

    The cardiovascular responses to a series of selective histamine H3 receptor agonists, (R) alpha-methylhistamine, imetit and immepip and selective antagonists, thioperamide, clobenpropit and clophenpropit, were studied in anaesthetized rats. At 0.003-1 mumol/kg i.v. doses, H3 agonists failed to produce any significant change in the basal blood pressure and heart rate. Larger doses of (R) alpha-methylhistamine increased the blood pressure and heart rate and higher doses of imetit caused vasodepressor responses and reduced heart rate, whereas immepip proved virtually inactive. While (R) alpha-methylhistamine-induced effects were not blocked by histamine H1-, H2- and H3-receptor antagonists, they were however reduced by idazoxan and propranolol, which indicates that the mechanisms involved are adrenergic. The effects induced by imetit are not related to histamine H3 receptors but are mediated by indirect (via 5HT3 receptors) cholinergic mechanisms, since these effects were prevented by 1 mg/kg i.v. atropine and by 0.1 mg/kg i.v. ondansetron. Similarly, the H3 antagonists per se failed to change basal cardiovascular function up to 10 mumol/kg i.v. and only at 30 mumol/kg i.v. were marked decreases observed in the blood pressure and heart rate with a significant reduction in the effects of noradrenaline. These data indicate that in anaesthetized rats, histamine H3 receptor activation or blockade has no effect on basal cardiovascular function. The effects recorded after the administration of large doses of (R) alpha-methylhistamine and imetit are clearly unrelated to histamine H3 receptors and should be taken into account when using these compounds as H3 ligands for "in vivo" experiments.

  1. Antagonists of the kappa opioid receptor.

    PubMed

    Urbano, Mariangela; Guerrero, Miguel; Rosen, Hugh; Roberts, Edward

    2014-05-01

    The research community has increasingly focused on the development of OPRK antagonists as pharmacotherapies for the treatment of depression, anxiety, addictive disorders and other psychiatric conditions produced or exacerbated by stress. Short-acting OPRK antagonists have been recently developed as a potential improvement over long-acting prototypic ligands including nor-BNI and JDTic. Remarkably the short-acting LY2456302 is undergoing phase II clinical trials for the augmentation of the antidepressant therapy in treatment-resistant depression. This Letter reviews relevant chemical and pharmacological advances in the identification and development of OPRK antagonists.

  2. Cross-talk from β-adrenergic receptors modulates α2A-adrenergic receptor endocytosis in sympathetic neurons via protein kinase A and spinophilin.

    PubMed

    Cottingham, Christopher; Lu, Roujian; Jiao, Kai; Wang, Qin

    2013-10-04

    Inter-regulation of adrenergic receptors (ARs) via cross-talk is a long appreciated but mechanistically unclear physiological phenomenon. Evidence from the AR literature and our own extensive studies on regulation of α2AARs by the scaffolding protein spinophilin have illuminated a potential novel mechanism for cross-talk from β to α2ARs. In the present study, we have characterized a mode of endogenous AR cross-talk in native adrenergic neurons whereby canonical βAR-mediated signaling modulates spinophilin-regulated α2AAR endocytosis through PKA. Our findings demonstrate that co-activation of β and α2AARs, either by application of endogenous agonist or by simultaneous stimulation with distinct selective agonists, results in acceleration of endogenous α2AAR endocytosis in native neurons. We show that receptor-independent PKA activation by forskolin is sufficient to accelerate α2AAR endocytosis and that α2AAR stimulation alone drives accelerated endocytosis in spinophilin-null neurons. Endocytic response acceleration by β/α2AAR co-activation is blocked by PKA inhibition and lost in spinophilin-null neurons, consistent with our previous finding that spinophilin is a substrate for phosphorylation by PKA that disrupts its interaction with α2AARs. Importantly, we show that α2AR agonist-mediated α2AAR/spinophilin interaction is blocked by βAR co-activation in a PKA-dependent fashion. We therefore propose a novel mechanism for cross-talk from β to α2ARs, whereby canonical βAR-mediated signaling coupled to PKA activation results in phosphorylation of spinophilin, disrupting its interaction with α2AARs and accelerating α2AAR endocytic responses. This mechanism of cross-talk has significant implications for endogenous adrenergic physiology and for therapeutic targeting of β and α2AARs.

  3. Effect of alpha(1)-adrenergic antagonist prazosin on behavioral alterations induced by MK-801 in a spatial memory task in Long-Evans rats.

    PubMed

    Stuchlík, A; Petrásek, T; Vales, K

    2009-01-01

    Animal models of neuropsychiatric disorders are current topics in behavioral neuroscience. Application of non-competitive antagonists of NMDA receptors (such as MK-801) was proposed as a model of schizophrenia, as it leads to specific behavioral alterations, which are partly analogous to human psychotic symptoms. This study examined an animal model of schizophrenia induced by a systemic application of MK-801 (0.15 and 0.20 mg/kg) into rats tested in the active allothetic place avoidance (AAPA) task. Previous studies suggested that MK-801 may interact in vivo with other neurotransmitter systems, including noradrenergic system. Our experiments therefore evaluated the hypothesis that both locomotor stimulation and deficit in avoidance behavior in AAPA task induced by this drug would be reversible by application of alpha(1)-adrenergic antagonist prazosin (1 and 2 mg/kg). The results showed that both doses of prazosin partially reversed hyperlocomotion induced by higher doses of MK-801 and an avoidance deficit measured as number of entrances into the shock sector. Interestingly, no effect of prazosin on the MK-801-induced decrease of maximum time between two entrances (another measure of cognitive performance) was observed. These results support previous data showing that prazosin can compensate for the hyperlocomotion induced by MK-801 and newly show that this partial reduction sustains even in the forced locomotor conditions, which are involved in the AAPA task. The study also shows that certain parameters of avoidance efficiency may be closely related to locomotor activity, whereas other measures of cognition may more selectively reflect cognitive changes.

  4. Loss of platelet alpha 2-adrenergic receptors during simulated extracorporeal circulation: prevention with prostaglandin E1

    SciTech Connect

    Wachtogel, Y.T.; Musial, J.; Jenkin, B.; Niewiarowski, S.; Edmunds, L.H. Jr.; Colman, R.W.

    1985-05-01

    Cardiopulmonary bypass prolongs bleeding time and increases postoperative blood loss. During in vitro recirculation in an extracorporeal circuit containing a membrane oxygenator and primed with fresh heparinized human blood, the authors previously observed thrombocytopenia, impaired platelet aggregation, and depletion of granular contents, all of which were prevented with prostaglandin E1 (PGE1). To investigate these changes further, they studied the number and affinity of platelet alpha 2-adrenergic receptors by measuring the binding of /sup 3/H-yohimbine. Before recirculation, they found 235 alpha 2-adrenergic receptors per platelet, a Kd of 3.37 nmol/L, complete aggregation with 1.04 mumol/L epinephrine, and a platelet count of 281,000 microliters/sup -1/. After 2 minutes of recirculation, 9.44 mumol/L epinephrine was required to produce complete aggregation, and the platelet count was 104,000 microliters-1 (44% of control). After 2 hours of recirculation, the platelet count had increased to 123,000 microliters/sup -1/. However, epinephrine did not induce platelet aggregation even at 100 mumol/L. Moreover, alpha 2-adrenergic binding sites were not detectable, and affinity for yohimbine could not be calculated. Two minutes after PGE1 0.3 mumol/L was added to the circuit, platelet numbers, response to epinephrine, alpha 2-adrenergic binding sites per platelet, and affinity for yohimbine were not significantly different from control values. At 2 hours, the number of alpha 2-adrenergic sites was not significantly changed from control, but the affinity of yohimbine for platelets was significantly decreased 2.5-fold.

  5. Solution structures and molecular interactions of selective melanocortin receptor antagonists.

    PubMed

    Lee, Chul-Jin; Yun, Ji-Hye; Lim, Sung-Kil; Lee, Weontae

    2010-12-01

    The solution structures and inter-molecular interaction of the cyclic melanocortin antagonists SHU9119, JKC363, HS014, and HS024 with receptor molecules have been determined by NMR spectroscopy and molecular modeling. While SHU9119 is known as a nonselective antagonist, JKC363, HS014, and HS024 are selective for the melanocortin subtype-4 receptor (MC4R) involved in modulation of food intake. Data from NMR and molecular dynamics suggest that the conformation of the Trp9 sidechain in the three MC4R-selective antagonists is quite different from that of SHU9119. This result strongly supports the concept that the spatial orientation of the hydrophobic aromatic residue is more important for determining selectivity than the presence of a basic, "arginine-like" moiety responsible for biological activity. We propose that the conformation of hydrophobic residues of MCR antagonists is critical for receptor-specific selectivity.

  6. The orphan nuclear receptor, NOR-1, is a target of beta-adrenergic signaling in skeletal muscle.

    PubMed

    Pearen, Michael A; Ryall, James G; Maxwell, Megan A; Ohkura, Naganari; Lynch, Gordon S; Muscat, George E O

    2006-11-01

    beta-Adrenergic receptor (beta-AR) agonists induce Nur77 mRNA expression in the C2C12 skeletal muscle cell culture model and elicit skeletal muscle hypertrophy. We previously demonstrated that Nur77 (NR4A1) is involved in lipolysis and gene expression associated with the regulation of lipid homeostasis. Subsequently it was demonstrated by another group that beta-AR agonists and cold exposure-induced Nur77 expression in brown adipocytes and brown adipose tissue, respectively. Moreover, NOR-1 (NR4A3) was hyperinduced by cold exposure in the nur77(-/-) animal model. These studies underscored the importance of understanding the role of NOR-1 in skeletal muscle. In this context we observed 30-480 min of beta-AR agonist treatment significantly and transiently increased expression of the orphan nuclear receptor NOR-1 in both mouse skeletal muscle tissue (plantaris) and C2C12 skeletal muscle cells. Specific beta(2)- and beta(3)-AR agonists had similar effects as the pan-agonist and were blocked by the beta-AR antagonist propranolol. Moreover, in agreement with these observations, isoprenaline also significantly increased the activity of the NOR-1 promoter. Stable exogenous expression of a NOR-1 small interfering RNA (but not the negative control small interfering RNA) in skeletal muscle cells significantly repressed endogenous NOR-1 mRNA expression and led to changes in the expression of genes involved in the control of lipid use and muscle mass underscored by a dramatic increase in myostatin mRNA expression. Concordantly the myostatin promoter was repressed by NOR-1 expression. In conclusion, NOR-1 is highly responsive to beta-adrenergic signaling and regulates the expression of genes controlling fatty acid use and muscle mass.

  7. 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

  8. Adrenergic β2-receptors mediates visceral hypersensitivity induced by heterotypic intermittent stress in rats.

    PubMed

    Zhang, Chunhua; Rui, Yun-Yun; Zhou, Yuan-Yuan; Ju, Zhong; Zhang, Hong-Hong; Hu, Chuang-Ying; Xiao, Ying; Xu, Guang-Yin

    2014-01-01

    Chronic visceral pain in patients with irritable bowel syndrome (IBS) has been difficult to treat effectively partially because its pathophysiology is not fully understood. Recent studies show that norepinephrine (NE) plays an important role in the development of visceral hypersensitivity. In this study, we designed to investigate the role of adrenergic signaling in visceral hypersensitivity induced by heterotypical intermittent stress (HIS). Abdominal withdrawal reflex scores (AWRs) used as visceral sensitivity were determined by measuring the visceromoter responses to colorectal distension. Colon-specific dorsal root ganglia neurons (DRGs) were labeled by injection of DiI into the colon wall and were acutely dissociated for whole-cell patch-clamp recordings. Blood plasma level of NE was measured using radioimmunoassay kits. The expression of β2-adrenoceptors was measured by western blotting. We showed that HIS-induced visceral hypersensitivity was attenuated by systemic administration of a β-adrenoceptor antagonist propranolol, in a dose-dependent manner, but not by a α-adrenoceptor antagonist phentolamine. Using specific β-adrenoceptor antagonists, HIS-induced visceral hypersensitivity was alleviated by β2 adrenoceptor antagonist but not by β1- or β3-adrenoceptor antagonist. Administration of a selective β2-adrenoceptor antagonist also normalized hyperexcitability of colon-innervating DRG neurons of HIS rats. Furthermore, administration of β-adrenoceptor antagonist suppressed sustained potassium current density (IK) without any alteration of fast-inactivating potassium current density (IA). Conversely, administration of NE enhanced the neuronal excitability and produced visceral hypersensitivity in healthy control rats, and blocked by β2-adrenoceptor antagonists. In addition, HIS significantly enhanced the NE concentration in the blood plasma but did not change the expression of β2-adrenoceptor in DRGs and the muscularis externa of the colon. The

  9. β-Adrenergic agonist and antagonist regulation of autophagy in HepG2 cells, primary mouse hepatocytes, and mouse liver.

    PubMed

    Farah, Benjamin L; Sinha, Rohit A; Wu, Yajun; Singh, Brijesh K; Zhou, Jin; Bay, Boon-Huat; Yen, Paul M

    2014-01-01

    Autophagy recently has been shown to be involved in normal hepatic function and in pathological conditions such as non-alcoholic fatty liver disease. Adrenergic signalling also is an important regulator of hepatic metabolism and function. However, currently little is known about the potential role of adrenergic signaling on hepatic autophagy, and whether the β-adrenergic receptor itself may be a key regulator of autophagy. To address these issues, we investigated the actions of the β2-adrenergic receptor agonist, clenbuterol on hepatic autophagy. Surprisingly, we found that clenbuterol stimulated autophagy and autophagic flux in hepatoma cells, primary hepatocytes and in vivo. Similar effects also were observed with epinephrine treatment. Interestingly, propranolol caused a late block in autophagy in the absence and presence of clenbuterol, both in cell culture and in vivo. Thus, our results demonstrate that the β2-adrenergic receptor is a key regulator of hepatic autophagy, and that the β-blocker propranolol can independently induce a late block in autophagy.

  10. Beta-adrenergic antagonist propranolol inhibits mammalian cell lysosome spreading and invasion by Trypanosoma cruzi metacyclic forms.

    PubMed

    Macedo, Silene; Rodrigues, João Paulo Ferreira; Schenkman, Sergio; Yoshida, Nobuko

    2017-01-19

    The involvement of β-adrenergic receptor (β-AR) in host cell invasion by Trypanosoma cruzi metacyclic trypomastigote (MT) is not known. We examined whether isoproterenol, an agonist of β-AR, or nonselective β-blocker propranolol affected MT internalization mediated the stage-specific surface molecule gp82. Treatment of HeLa cells with propranolol significantly inhibited MT invasion whereas isoproterenol had no effect. Propranolol, but not isoproterenol, also inhibited the lysosome spreading required for gp82-dependent MT invasion. The effect of propranolol in inhibiting MT internalization was not due to the prevention of gp82 interaction with β-AR. It was mainly associated with its ability to impair lysosome spreading.

  11. Adrenergic receptor and catecholamine distribution in rat cerebral cortex: binding studies with [3H]prazosin, [3H]idazoxan and [3H]dihydroalprenolol.

    PubMed

    Diop, L; Brière, R; Grondin, L; Reader, T A

    1987-02-03

    The tritiated adrenergic antagonists [3H]dihydroalprenolol ([3H]DHA; beta-receptors), [3H]prazosin ([3H]PRZ; alpha 1-receptors), and [3H]idazoxan ([3H]IDA; alpha 2-receptors) were used to determine the distribution of these sites in 5 defined areas of the adult rat cerebral cortex. The highest density of [3H]PRZ binding was found in the prefrontal cortex, with a lower and homogeneous distribution for the frontal, parietal, occipital and temporal areas. The [3H]IDA binding sites were fairly uniform for all areas, except for the temporal cortex where it was very dense. In contrast, beta-adrenoceptors labelled by [3H]DHA were very homogeneous for all the regions examined. The functional significance of the distribution of alpha 1, alpha 2 and beta-adrenoceptors is discussed in relation to the catecholamine innervation and monoamine contents measured by high performance liquid chromatography.

  12. Functional interactions between the oxytocin receptor and the β2-adrenergic receptor: implications for ERK1/2 activation in human myometrial cells.

    PubMed

    Wrzal, Paulina K; Goupil, Eugénie; Laporte, Stéphane A; Hébert, Terence E; Zingg, Hans H

    2012-01-01

    The Gq-coupled oxytocin receptor (OTR) and the Gs-coupled β(2)-adrenergic receptor (β(2)AR) are both expressed in myometrial cells and mediate uterine contraction and relaxation, respectively. The two receptors represent important pharmacological targets as OTR antagonists and β(2)AR agonists are used to control pre-term uterine contractions. Despite their physiologically antagonistic effects, both receptors activate the MAP kinases ERK1/2, which has been implicated in uterine contraction and the onset of labor. To determine the signalling pathways involved in mediating the ERK1/2 response, we assessed the effect of blockers of specific G protein-associated pathways. In human myometrial hTERT-C3 cells, inhibition of Gαi as well as inhibition of the Gαq/PKC pathway led to a reduction of both OTR- and β(2)AR-mediated ERK1/2 activation. The involvement of Gαq/PKC in β(2)AR-mediated ERK1/2 induction was unexpected. To test whether the emergence of this novel signalling mechanism was dependent on OTR expression in the same cell, we conducted experiments in HEK 293 cells that were transfected with the β(2)AR alone or co-transfected with the OTR. Using this approach, we found that β(2)AR-mediated ERK1/2 responses became sensitive to PKC inhibition only in cells co-transfected with the OTR. Inhibitor studies indicated the involvement of an atypical PKC isoform in this process. We confirmed the specific involvement of PKCζ in this pathway by assessing PKCζ translocation to the cell membrane. Consistent with our inhibitor studies, we found that β(2)AR-mediated PKCζ translocation was dependent on co-expression of OTR. The present demonstration of a novel β(2)AR-coupled signalling pathway that is dependent on OTR co-expression is suggestive of a molecular interaction between the two receptors.

  13. 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

  14. Recent advances in the molecular pharmacology of the alpha 1-adrenergic receptors.

    PubMed

    Guarino, R D; Perez, D M; Piascik, M T

    1996-08-01

    This review is intended to discuss recent developments in the molecular pharmacology of the alpha 1-adrenergic receptor (alpha 1-AR) subtypes. After a brief historical development, we will focus on the more contemporary issues having to do with this receptor family. Emphasis will be put on recent data regarding the cloning, nomenclature, signalling mechanisms, and genomic organization of the alpha 1-AR subtypes. We will also highlight recent mutational studies that identify key amino acid residues involved in ligand binding, as well as the role of the alpha 1-AR subtypes in regulating physiologic processes.

  15. Desensitization of the insulin receptor by antireceptor antibodies in vivo is blocked by treatment of mice with beta-adrenergic agonists.

    PubMed

    Elias, D; Rapoport, M; Cohen, I R; Shechter, Y

    1988-06-01

    In previous studies we reported that immunization of mice with ungulate insulins induced the development of antiinsulin antibodies, which include an idiotype that appeared to recognize the part of the insulin molecule recognized by the hormone receptor. The antiinsulin antibodies of this idiotype were replaced spontaneously by antiidiotypic antibodies. The antiidiotypic antibodies, which persisted for about 14 d, mimicked insulin and functioned as antibodies to the insulin receptor. They induced down regulation, desensitization and refractoriness of the insulin receptor and disturbances in glucose homeostasis in vivo (Shechter, Y., D. Elias, R. Maron, and I.R. Cohen., 1984; Elias, D., R. Maron, I.R. Cohen, and Y. Shechter. 1984, J. Biol. Chem. 259: 6411-6419). We now report that effects of the antiidiotypic antibodies on the insulin receptor effector system can be modified pharmacologically. Administration of the beta-adrenergic agonist isoproterenol during the period of insulin resistance (days 26-40 after primary immunization), largely restored fat cell responsiveness to insulin, and eliminated the appearance of fasting hyperglycemia. This restoration appeared to be caused by inhibition of both insulin receptor desensitization and refractoriness. In contrast, down regulation of insulin receptors was not reversed by isoproterenol treatment in vivo. The effects of treatment with isoproterenol persisted for 2-4 d after termination of treatment. The beta-antagonist, propranolol and more so, the beta 1a-antagonist metoprolol, specifically blocked the effect of isoproterenol at a molar ratio of 3-10:1. Oral administration of the cAMP phosphodiesterase inhibitor, aminophylline, was also effective in inhibiting the development of desensitization in fat cells. These results indicate that treatment with beta 1-adrenergic agonists in vivo, or other agents that elevate cellular cAMP levels, can inhibit the development of the "postbinding" defects induced by insulin

  16. 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.

  17. Mivazerol, a novel compound with high specificity for alpha 2 adrenergic receptors: binding studies on different human and rat membrane preparations.

    PubMed

    Noyer, M; de Laveleye, F; Vauquelin, G; Gobert, J; Wülfert, E

    1994-03-01

    Mivazerol, 3-[1(H-imidazol-4-yl)methyl]-2-hydroxybenzamide hydrochloride, a new potential anti-ischemic drug designed by UCB S.A. Pharma Sector, has been studied in binding experiments on adrenergic, dopaminergic, serotoninergic, muscarinic and idazoxan binding sites. Our results indicate that this compound displays high affinity and marked specificity for alpha 2 adrenoceptors. Mivazerol displaced the binding of the alpha 2 adrenoceptor antagonist [3H]RX 821002 to the alpha 2A adrenoceptors in human frontal cortex membranes with an apparent Ki value of 37 nM. The competition curve was shallow (nH = 0.55), suggesting that this compound acts as an alpha 2 adrenergic agonist. Mivazerol was also a potent competitor for [3H]RX 821002 binding to human platelet membranes (containing alpha 2A adrenoceptors) and rat kidney membranes (75% of the alpha 2 adrenoceptors of the alpha 2B subtype), indicating that this compound is not alpha 2 adrenoceptor subtype selective. Equilibrium dissociation constants for alpha 1 adrenoceptors (displacement of [3H]prazosin) and 5-HT1A receptors (displacement of [3H]rauwolscine) were respectively about 120 times (Ki = 4.4 microM) and 14 times (Ki = 530 nM) higher than that for the alpha 2 adrenoceptors. Equilibrium dissociation constants were approximately 1000 times higher for all other receptors tested in this study; namely beta 1 and beta 2 adrenoceptors, D1- and D2-dopamine receptors, M1-, M2- and M3-muscarinic receptors, 5-HT2 receptors and non-adrenergic idazoxan binding sites.

  18. SYNAPTIC TRANSLATION OF STRIATAL-ENRICHED TYROSINE PHOSPHATASE (STEP) AFTER β1-ADRENERGIC RECEPTOR STIMULATION

    PubMed Central

    Hu, Yaer; Zhang, Yang; Venkitaramani, Deepa V.; Lombroso, Paul J.

    2009-01-01

    The β-adrenergic system is implicated in long-term synaptic plasticity in the central nervous system, a process that requires protein synthesis. To identify proteins that are translated in response to β-adrenergic receptor stimulation and the pathways that regulate this process, we investigated the effects of isoproterenol on the translation of striatal-enriched protein tyrosine phosphatase (STEP) in both cortico-striatal slices and primary neuronal cultures. Isoproterenol stimulation induced a rapid dose-dependent increase in STEP expression. Anisomycin blocked the increase in STEP expression while actinomycin D had no effect, suggesting a translation-dependent mechanism. Isoproterenol-induced STEP translation required activation of β1 receptors. Application of the MEK inhibitor SL327 blocked both isoproterenol-induced activation of pERK and subsequent STEP translation. Inhibitors of PI3K (LY294002) or mTOR (rapamycin) also completely blocked STEP translation. These results suggest that co-activation of both the ERK and PI3K-Akt-mTOR pathways are required for STEP translation. As the substrates of STEP include ERK itself, these results suggest that STEP is translated upon β-adrenergic activation as part of a negative feedback mechanism. PMID:17623046

  19. 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.

  20. β Adrenergic Receptor Kinase C-Terminal Peptide Gene-Therapy Improves β2-Adrenergic Receptor-Dependent Neoangiogenesis after Hindlimb Ischemia.

    PubMed

    Cannavo, Alessandro; Liccardo, Daniela; Lymperopoulos, Anastasios; Gambino, Giuseppina; D'Amico, Maria Loreta; Rengo, Franco; Koch, Walter J; Leosco, Dario; Ferrara, Nicola; Rengo, Giuseppe

    2016-02-01

    After hindlimb ischemia (HI), increased catecholamine levels within the ischemic muscle can cause dysregulation of β2-adrenergic receptor (β2AR) signaling, leading to reduced revascularization. Indeed, in vivo β2AR overexpression via gene therapy enhances angiogenesis in a rat model of HI. G protein-coupled receptor kinase 2 (GRK2) is a key regulator of βAR signaling, and β adrenergic receptor kinase C-terminal peptide (βARKct), a peptide inhibitor of GRK2, has been shown to prevent βAR down-regulation and to protect cardiac myocytes and stem cells from ischemic injury through restoration of β2AR protective signaling (i.e., protein kinase B/endothelial nitric oxide synthase). Herein, we tested the potential therapeutic effects of adenoviral-mediated βARKct gene transfer in an experimental model of HI and its effects on βAR signaling and on endothelial cell (EC) function in vitro. Accordingly, in this study, we surgically induced HI in rats by femoral artery resection (FAR). Fifteen days of ischemia resulted in significant βAR down-regulation that was paralleled by an approximately 2-fold increase in GRK2 levels in the ischemic muscle. Importantly, in vivo gene transfer of the βARKct in the hindlimb of rats at the time of FAR resulted in a marked improvement of hindlimb perfusion, with increased capillary and βAR density in the ischemic muscle, compared with control groups. The effect of βARKct expression was also assessed in vitro in cultured ECs. Interestingly, ECs expressing the βARKct fenoterol, a β2AR-agonist, induced enhanced β2AR proangiogenic signaling and increased EC function. Our results suggest that βARKct gene therapy and subsequent GRK2 inhibition promotes angiogenesis in a model of HI by preventing ischemia-induced β2AR down-regulation.

  1. Allosteric equilibrium model explains steady-state coupling of beta-adrenergic receptors to adenylate cyclase in turkey erythrocyte membranes.

    PubMed

    Ugur, O; Onaran, H O

    1997-05-01

    We used a simple experimental approach to clarify some contradictory predictions of the collision coupling and equilibrium models (e.g. ternary complex, two-state ternary complex or quinternary complex), which describe G-protein-mediated beta-adrenergic receptor signalling in essentially different manners. Analysis of the steady-state coupling of beta-adrenoceptors to adenylate cyclase in turkey erythrocyte membranes showed that: (1) in the absence of an agonist, Gpp(NH)p (a hydrolysis-resistant analogue of GTP) can activate adenylate cyclase very slowly; (2) this activity reaches a steady state in approx. 5 h, the extent of activity depending on the concentration of the nucleotide; (3) isoprenaline-activated steady-state adenylate cyclase can be inactivated by propranolol (a competitive antagonist that relaxes the receptor activation), in the presence of Gpp(NH)p (which provides a virtual absence of GTPase) and millimolar concentrations of Mg2+ (the rate of this inactivation is relatively fast); (4) increasing the concentration of Gpp(NH)p can saturate the steady-state activity of adenylate cyclase. The saturated enzyme activity was lower than that induced by isoprenaline under the same conditions. This additional agonist-induced activation was reversible. In the light of these results, we conclude that agonist can also activate the guanine nucleotide-saturated system in the absence of GTPase by a mechanism other than guanine nucleotide exchange. We explain these phenomena in the framework of a quinternary complex model as an agonist-induced and receptor-mediated dissociation of guanine nucleotide-saturated residual heterotrimer, the equilibrium concentration of which is not necessarily zero. These results, which suggest a continuous interaction between receptor and G-protein, can hardly be accommodated by the collision coupling model that was originally suggested for the present experimental system and then applied to many other G-protein systems. Therefore we

  2. 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.

  3. 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.

  4. Thermodynamic analysis of antagonist and agonist interactions with dopamine receptors.

    PubMed

    Duarte, E P; Oliveira, C R; Carvalho, A P

    1988-03-01

    The binding of [3H]spiperone to dopamine D-2 receptors and its inhibition by antagonists and agonists were examined in microsomes derived from the sheep caudate nucleus, at temperatures between 37 and 1 degree C, and the thermodynamic parameters of the binding were evaluated. The affinity of the receptor for the antagonists, spiperone and (+)-butaclamol, decreased as the incubation temperature decreased; the affinity for haloperidol did not further decrease at temperatures below 15 degrees C. The binding of the antagonists was associated with very large increases in entropy, as expected for hydrophobic interactions. The enthalpy and entropy changes associated with haloperidol binding were dependent on temperature, in contrast to those associated with spiperone and (+)-butaclamol. The magnitude of the entropy increase associated with the specific binding of the antagonists did not correlate with the degree of lipophilicity of these drugs. The data suggest that, in addition to hydrophobic forces, other forces are also involved in the antagonist-dopamine receptor interactions, and that a conformational change of the receptor could occur when the antagonist binds. Agonist binding data are consistent with a two-state model of the receptor, a high-affinity state (RH) and a low-affinity state (RL). The affinity of dopamine binding to the RH decreased with decreasing temperatures below 20 degrees C, whereas the affinity for the RL increased at low temperatures. In contrast, the affinity of apomorphine for both states of receptor decreased as the temperature decreased from 30 to 8 degrees C. A clear distinction between the energetics of high-affinity and low-affinity agonist binding was observed. The formation of the high-affinity complex was associated with larger increases in enthalpy and entropy than the interaction with the low-affinity state was. The results suggest that the interaction of the receptor with the G-proteins, induced or stabilized by the binding of

  5. Beta adrenergic receptor blockade of feline myocardium. Cardiac mechanics, energetics, and beta adrenoceptor regulation.

    PubMed Central

    Cooper, G; Kent, R L; McGonigle, P; Watanabe, A M

    1986-01-01

    Myocardial oxygen consumption is regulated by interrelated mechanical and inotropic conditions; there is a parallel increase in the aerobic metabolism and inotropic state during beta-adrenergic stimulation under fixed mechanical conditions. In contrast, there is some evidence that beta-blockade may reduce oxygen consumption through effects independent of its influence on mechanical conditions and contractile state, and that prolonged beta-blockade may sensitize the myocardium to beta-adrenergic stimulation. To clarify these two points, the present study examined the relationship of myocardial energetics to mechanics and inotropism during acute beta-blockade and after the withdrawal of long-term beta-blockade, whereupon the basis for any effect observed was sought by characterizing the number, affinity, and affinity states of the beta-receptors as well as the coupling of activated beta-receptors to cyclic AMP generation. Studies of right ventricular papillary muscles from control and chronically beta-blocked cats demonstrated contractile and energetic properties as well as dose-response behavior and inotropic specificity suggestive of an increase in myocardial sensitivity to beta-adrenoceptor stimulation in the latter group. Assays of cardiac beta-adrenoceptors from further groups of control and pretreated cats, both in cardiac tissue and in isolated cardiac muscle cells, failed to define a difference between the two groups either in terms of receptor number and affinity or in terms of the proportion of receptors in the high-affinity state. However, coupling of the activated beta-adrenoceptors to cyclic AMP generation was enhanced in cardiac muscle cells from chronically beta-blocked cats. These data demonstrate that beta-adrenoceptor blockade (a) produces parallel effects on inotropic state and oxygen consumption without an independent effect on either and (b) increases myocardial sensitivity to beta-adrenergic stimulation after beta-blockade withdrawal, not by "up

  6. High-throughput chemiluminometric genotyping of single nucleotide polymorphisms of histamine, serotonin, and adrenergic receptor genes.

    PubMed

    Toubanaki, Dimitra K; Christopoulos, Theodore K; Ioannou, Penelope C; Flordellis, Christodoulos S

    2009-02-01

    Several pharmacogenetic studies are focused on the investigation of the relation between the efficacy of various antipsychotic agents (e.g., clozapine) and the genetic profile of the patient with an emphasis on genes that code for neurotransmitter receptors such as histamine, serotonin, and adrenergic receptors. We report a high-throughput method for genotyping of single nucleotide polymorphisms (SNPs) within the genes of histamine H2 receptor (HRH2), serotonin receptor (HTR2A1 and HTR2A2), and beta(3) adrenergic receptor (ADRB3). The method combines the high specificity of allele discrimination by oligonucleotide ligation reaction (OLR) and the superior sensitivity and simplicity of chemiluminometric detection in a microtiter well assay configuration. The genomic region that spans the locus of interest is first amplified by polymerase chain reaction (PCR). Subsequently, an oligonucleotide ligation reaction is performed using a biotinylated common probe and two allele-specific probes that are labeled at the 3' end with digoxigenin and fluorescein. The ligation products are immobilized in polystyrene wells via biotin-streptavidin interaction, and the hybrids are denatured. Detection is accomplished by the addition of alkaline phosphatase-conjugated anti-digoxigenin or anti-fluorescein antibodies in combination with a chemiluminogenic substrate. The ratio of the luminescence signals obtained from digoxigenin and fluorescein indicates the genotype of the sample. The method was applied successfully to the genotyping of 23 blood samples for all four SNPs. The results were in concordance with both PCR-restriction fragment length polymorphism analysis and sequencing.

  7. Characterization of a β-Adrenergic-Like Octopamine Receptor in the Oriental Fruit Fly, Bactrocera dorsalis (Hendel)

    PubMed Central

    Li, Hui-Min; Jiang, Hong-Bo; Gui, Shun-Hua; Liu, Xiao-Qiang; Liu, Hong; Lu, Xue-Ping; Smagghe, Guy; Wang, Jin-Jun

    2016-01-01

    The biogenic amine octopamine plays a critical role in the regulation of many physiological processes in insects. Octopamine transmits its action through a set of specific G-protein coupled receptors (GPCRs), namely octopamine receptors. Here, we report on a β-adrenergic-like octopamine receptor gene (BdOctβR1) from the oriental fruit fly, Bactrocera dorsalis (Hendel), a destructive agricultural pest that occurs in North America and the Asia-Pacific region. As indicated by RT-qPCR, BdOctβR1 was highly expressed in the central nervous system (CNS) and Malpighian tubules (MT) in the adult flies, suggesting it may undertake important roles in neural signaling in the CNS as well as physiological functions in the MT of this fly. Furthermore, its ligand specificities were tested in a heterologous expression system where BdOctβR1 was expressed in HEK-293 cells. Based on cyclic AMP response assays, we found that BdOctβR1 could be activated by octopamine in a concentration-dependent manner, confirming that this receptor was functional, while tyramine and dopamine had much less potency than octopamine. Naphazoline possessed the highest agonistic activity among the tested agonists. In antagonistic assays, mianserin had the strongest activity and was followed by phentolamine and chlorpromazine. Furthermore, when the flies were kept under starvation, there was a corresponding increase in the transcript level of BdOctβR1, while high or low temperature stress could not induce significant expression changes. The above results suggest that BdOctβR1 may be involved in the regulation of feeding processes in Bactrocera dorsalis and may provide new potential insecticide leads targeting octopamine receptors. PMID:27669213

  8. p-( sup 125 I)iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor

    SciTech Connect

    Gerhardt, M.A.; Wade, S.M.; Neubig, R.R. )

    1990-08-01

    The binding properties of p-(125I)iodoclonidine (( 125I)PIC) to human platelet membranes and the functional characteristics of PIC are reported. (125I)PIC bound rapidly and reversibly to platelet membranes, with a first-order association rate constant (kon) at room temperature of 8.0 +/- 2.7 x 10(6) M-1 sec-1 and a dissociation rate constant (koff) of 2.0 +/- 0.8 x 10(-3) sec-1. Scatchard plots of specific (125I)PIC binding (0.1-5 nM) were linear, with a Kd of 1.2 +/- 0.1 nM. (125I)PIC bound to the same number of high affinity sites as the alpha 2-adrenergic receptor (alpha 2-AR) full agonist (3H) bromoxidine (UK14,304), which represented approximately 40% of the sites bound by the antagonist (3H)yohimbine. Guanosine 5'-(beta, gamma-imido)triphosphate greatly reduced the amount of (125I)PIC bound (greater than 80%), without changing the Kd of the residual binding. In competition experiments, the alpha 2-AR-selective ligands yohimbine, bromoxidine, oxymetazoline, clonidine, p-aminoclonidine, (-)-epinephrine, and idazoxan all had Ki values in the low nanomolar range, whereas prazosin, propranolol, and serotonin yielded Ki values in the micromolar range. Epinephrine competition for (125I)PIC binding was stereoselective. Competition for (3H)bromoxidine binding by PIC gave a Ki of 1.0 nM (nH = 1.0), whereas competition for (3H)yohimbine could be resolved into high and low affinity components, with Ki values of 3.7 and 84 nM, respectively. PIC had minimal agonist activity in inhibiting adenylate cyclase in platelet membranes, but it potentiated platelet aggregation induced by ADP with an EC50 of 1.5 microM. PIC also inhibited epinephrine-induced aggregation, with an IC50 of 5.1 microM. Thus, PIC behaves as a partial agonist in a human platelet aggregation assay. (125I)PIC binds to the alpha 2B-AR in NG-10815 cell membranes with a Kd of 0.5 +/- 0.1 nM.

  9. 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.

  10. 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.

  11. Mixed antagonistic effects of bilobalide at rho1 GABAC receptor.

    PubMed

    Huang, S H; Duke, R K; Chebib, M; Sasaki, K; Wada, K; Johnston, G A R

    2006-01-01

    Bilobalide was found to be a moderately potent antagonist with a weak use-dependent effect at recombinant human rho(1) GABA(C) receptors expressed in Xenopus oocytes using two-electrode voltage clamp methodology. Antagonism of bilobalide at homomeric rho(1) GABA(C) receptors appeared to be mixed. At low concentration, bilobalide (3 microM) caused a parallel right shift and surmountable GABA maximal response of the GABA dose-response curve characteristic of a competitive antagonist. At high concentrations, bilobalide (10-100 microM) caused nonparallel right shifts and reduced maximal GABA responses of GABA dose-response curves characteristic of a noncompetitive antagonist. The potency of bilobalide appears to be dependent on the concentrations of GABA and was more potent at lower GABA concentrations. The mechanism of action of bilobalide at rho(1) GABA(C) receptors appears to be similar to that of the chloride channel blocker picrotoxinin.

  12. Third Generation Mineralocorticoid Receptor Antagonists; Why We Need a Fourth

    PubMed Central

    Gomez-Sanchez, Elise

    2015-01-01

    The first mineralocorticoid receptor (MR) antagonist, spironolactone, was developed almost 60 years ago to treat primary aldosteronism and pathological edema. Its use waned in part due to its lack of selectivity. Subsequently knowledge of the scope of MR function was expanded along with clinical evidence of the therapeutic importance of MR antagonists to prevent the ravages of inappropriate MR activation. Forty-two years elapsed between the first and MR-selective second generation of MR antagonists. Fifteen years later, despite serious shortcomings of the existing antagonists, a third generation antagonist has yet to be marketed. Progress has been slowed by the lack of appreciation of the large variety of cell types that express the MR and its diverse cell-type-specific actions, as well as its uniquely complex interactions actions at the molecular level. New MR antagonists should preferentially target the inflammatory and fibrotic effects of MR and perhaps its excitatory effects on sympathetic nervous system, but not the renal tubular epithelium or neurons of the cortex and hippocampus. This review briefly describes efforts to develop a third generation MR antagonist and why fourth generation antagonists and selective agonists based on structural determinants of tissue and ligand-specific MR activation should be contemplated. PMID:26466326

  13. G protein antagonists. A novel hydrophobic peptide competes with receptor for G protein binding.

    PubMed

    Mukai, H; Munekata, E; Higashijima, T

    1992-08-15

    A substance P (SP) analog, [D-Pro4,D-Trp7,9,10] SP4-11, is known to inhibit the actions of various structurally unrelated messenger molecules as well as SP. Our studies on the effects of this peptide on the regulation of purified G proteins by receptor showed that at least some of the biological effects of the peptide can be explained by the ability of the peptide to block the activation of G proteins by receptors. Here we report that a novel truncated SP-related peptide, pGlu-Gln-D-Trp-Phe-D-Trp-D-Trp-Met-NH2, inhibited the activation of G(i) or G(o) by M2 muscarinic cholinergic receptor (M2 mAChR) or of Gs by beta-adrenergic receptor in the reconstituted phospholipid vesicles, assayed by receptor-promoted GTP hydrolysis. The inhibition by the peptide was apparently reversible and competitive with respect to receptor binding to G proteins; the inhibition could be overcome by increasing the concentration of receptor in the vesicles and was not altered by changes in the concentration of G protein. The competing effects of the peptide were used to analyze the effect of agonist on receptor-G protein interaction. The concentration change of muscarinic agonist did not alter the inhibitory effects of the peptide on M2 mAChR-promoted GTPase by G(o), which is consistent with the idea that agonist increases the regulatory efficiency of the receptor but does not alter its affinity for G proteins. This new group of compounds (G protein antagonists) is a promising tool to study receptor-G protein interaction quantitatively.

  14. S18327 (1-[2-[4-(6-fluoro-1, 2-benzisoxazol-3-yl)piperid-1-yl]ethyl]3-phenyl imidazolin-2-one), a novel, potential antipsychotic displaying marked antagonist properties at alpha(1)- and alpha(2)-adrenergic receptors: II. Functional profile and a multiparametric comparison with haloperidol, clozapine, and 11 other antipsychotic agents.

    PubMed

    Millan, M J; Brocco, M; Rivet, J M; Audinot, V; Newman-Tancredi, A; Maiofiss, L; Queriaux, S; Despaux, N; Peglion, J L; Dekeyne, A

    2000-01-01

    S18327 was dose-dependently active in several models of potential antipsychotic activity involving dopaminergic hyperactivity: inhibition of apomorphine-induced climbing in mice, of cocaine- and amphetamine-induced hyperlocomotion in rats, and of conditioned avoidance responses in rats. Furthermore, reflecting its high affinity at serotonin(2A) sites, S18327 potently blocked phencyclidine-induced locomotion and 1-[2, 5-dimethoxy-4-iodophenyl]-2-aminopropane-induced head-twitches in rats. In models of glutamatergic hypoactivity, S18327 blocked hyperlocomotion and spontaneous tail-flicks elicited by the N-methyl-D-aspartate antagonist dizocilpine. The actions of S18327, together with its binding profile at multiple monoaminergic receptors (15 parameters in total), were compared with those of clozapine, haloperidol, and 11 other antipsychotics by multiparametric analysis, and the resulting dendrogram positioned S18327 close to clozapine. Consistent with a clopazine-like profile, S18327 generalized to a clozapine discriminative stimulus and evoked latent inhibition in rats, blocked aggression in isolated mice, and displayed anxiolytic properties in the ultrasonic vocalization and Vogel procedures in rats. Relative to the above paradigms, only markedly (>20-fold) higher doses of S18327 were active in models predictive of potential extrapyramidal side effects: induction of catalepsy and prolactin secretion, and inhibition of methylphenidate-induced gnawing in rats. S18327 showed only modest affinity for histaminic and muscarinic receptors. Multiparametric analysis of these data distinguished S18327 from both haloperidol (high extrapyramidal potential) and clozapine (high histaminic and muscarinic affinity). In conclusion, S18327 displays a broad-based pattern of potential antipsychotic activity at doses appreciably lower than those eliciting extrapyramidal side effects. In this respect, S18327 closely resembles clozapine, but it is chemically distinct and displays weak

  15. An Alpha-1A Adrenergic Receptor Agonist Prevents Acute Doxorubicin Cardiomyopathy in Male Mice

    PubMed Central

    Montgomery, Megan D.; Chan, Trevor; Swigart, Philip M.; Myagmar, Bat-erdene; Dash, Rajesh; Simpson, Paul C.

    2017-01-01

    Alpha-1 adrenergic receptors mediate adaptive effects in the heart and cardiac myocytes, and a myocyte survival pathway involving the alpha-1A receptor subtype and ERK activation exists in vitro. However, data in vivo are limited. Here we tested A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide), a selective imidazoline agonist for the alpha-1A. A61603 was the most potent alpha-1-agonist in activating ERK in neonatal rat ventricular myocytes. A61603 activated ERK in adult mouse ventricular myocytes and protected the cells from death caused by the anthracycline doxorubicin. A low dose of A61603 (10 ng/kg/d) activated ERK in the mouse heart in vivo, but did not change blood pressure. In male mice, concurrent subcutaneous A61603 infusion at 10 ng/kg/d for 7 days after a single intraperitoneal dose of doxorubicin (25 mg/kg) increased survival, improved cardiac function, heart rate, and cardiac output by echocardiography, and reduced cardiac cell necrosis and apoptosis and myocardial fibrosis. All protective effects were lost in alpha-1A-knockout mice. In female mice, doxorubicin at doses higher than in males (35–40 mg/kg) caused less cardiac toxicity than in males. We conclude that the alpha-1A-selective agonist A61603, via the alpha-1A adrenergic receptor, prevents doxorubicin cardiomyopathy in male mice, supporting the theory that alpha-1A adrenergic receptor agonists have potential as novel heart failure therapies. PMID:28081170

  16. A molecular dynamics approach to receptor mapping: application to the 5HT3 and beta 2-adrenergic receptors.

    PubMed

    Gouldson, P R; Winn, P J; Reynolds, C A

    1995-09-29

    A molecular dynamics-based approach to receptor mapping is proposed, based on the method of Rizzi (Rizzi, J. P.; et al. J. Med. Chem. 1990, 33, 2721). In Rizzi's method, the interaction energy between a series of drug molecules and probe atoms (which mimic functional groups on the receptor, such as hydrogen bond donors) was calculated. These interactions were calculated on a three-dimensional grid within a molecular mechanics parameters, were placed at these minima. The distances between the dummy atom sites were monitored during molecular dynamics simulations and plotted as distance distribution functions. Important distances within the receptor became apparent, as drugs with a common mode of binding share similar peaks in the distance distribution functions. In the case of specific 5HT3 ligands, the important donor--acceptor distance within the receptor has a range of ca. 7.9--8.9 A. In the case of specific beta 2-adrenergic ligands, the important donor--acceptor distances within the receptor lie between ca. 7--9 A and between 8 and 10 A. These distances distribution functions were used to assess three different models of the beta 2-adrenergic G-protein-coupled receptor. The comparison of the distance distribution functions for the simulation with the actual donor--acceptor distances in the receptor models suggested that two of the three receptor models were much more consistent with the receptor-mapping studies. These receptor-mapping studies gave support for the use of rhodopsin, rather than the bacteriorhodopsin template, for modeling G-protein-coupled receptors but also sounded a warning that agreement with binding data from site-directed mutagenesis experiments does not necessarily validate a receptor model.

  17. 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.

  18. Biochemical profile of YM992, a novel selective serotonin reuptake inhibitor with 5-HT2A receptor antagonistic activity.

    PubMed

    Hatanaka, K; Nomura, T; Hidaka, K; Takeuchi, H; Yatsugi, S; Fujii, M; Yamaguchi, T

    1996-01-01

    YM992, (S)-2-[[(7-fluoro-4-indanyl)oxy]methyl]morpholine monohydrochloride, exhibited the biochemical profile of a selective serotonin (5-HT) reuptake inhibitor (SSRI) with 5-HT2A receptor antagonistic activity. YM922 showed the same high affinity as fluoxetine against the 5-HT reuptake site (Ki = 21 nM) and a similar affinity to that of crazodone against the 5-HT2A receptor (Ki = 86 nM). In other receptor binding studies, an affinity for the adrenergic alpha 1 receptor (Ki = 200 nM) and 5-HT2C receptor (Ki = 680 nM) was observed. In a monoamine uptake study, YM992 showed a selective 5-HT uptake inhibition (IC50 = 0.15 microM), but only very weakly inhibited both noradrenaline (NA) and dopamine (DA) uptake (IC50 = 3.1 microM (NA), > 10 microM (DA)). YM992 was also found to potently inhibit the aggregation of human platelets (IC50 = 1.9 microM), revealing antagonistic activity for the 5-HT2A receptor in vitro. Enhanced serotonergic neurotransmission, in particular that mediated by the 5-HT1A receptor, has recently been reported to be important in the long-term treatment of depressive disorders with antidepressants. In addition, some 5-HT1A receptor-mediated responses are known to be potentiated by co-administration of 5-HT2A receptor antagonists. Thus, YM992, having both selective 5-HT reuptake inhibition and 5-HT2A antagonistic activity, might show potent therapeutic activity as a novel antidepressant in comparison with conventional SSRIs.

  19. A comparison of adrenergic receptors of rat ascites hepatoma AH130 cells with those of normal rat hepatocytes.

    PubMed

    Sanae, F; Miyamoto, K; Koshiura, R

    1988-04-01

    The pharmacological specificity of adrenergic receptors in the plasma membrane of rat ascites hepatoma AH130 cells was compared with that in normal rat hepatocytes. The number of [125I]iodocyanopindolol-binding sites was much greater in AH130 cells than in the hepatocytes. We characterized the alpha-adrenergic receptor subtypes using the alpha 1-selective ligand [3H]prazosin and the alpha 2-selective ligand [3H]clonidine. AH130 cells had fewer prazosin-binding sites than the hepatocytes and about 8 times as many clonidine-binding sites of high affinity. The results showed that the adrenergic receptors in AH130 cells have pharmacological properties that are very different from those of the receptors in normal rat hepatocytes.

  20. 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.

  1. GPCR engineering yields high-resolution structural insights into beta2-adrenergic receptor function.

    PubMed

    Rosenbaum, Daniel M; Cherezov, Vadim; Hanson, Michael A; Rasmussen, Søren G F; Thian, Foon Sun; Kobilka, Tong Sun; Choi, Hee-Jung; Yao, Xiao-Jie; Weis, William I; Stevens, Raymond C; Kobilka, Brian K

    2007-11-23

    The beta2-adrenergic receptor (beta2AR) is a well-studied prototype for heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) that respond to diffusible hormones and neurotransmitters. To overcome the structural flexibility of the beta2AR and to facilitate its crystallization, we engineered a beta2AR fusion protein in which T4 lysozyme (T4L) replaces most of the third intracellular loop of the GPCR ("beta2AR-T4L") and showed that this protein retains near-native pharmacologic properties. Analysis of adrenergic receptor ligand-binding mutants within the context of the reported high-resolution structure of beta2AR-T4L provides insights into inverse-agonist binding and the structural changes required to accommodate catecholamine agonists. Amino acids known to regulate receptor function are linked through packing interactions and a network of hydrogen bonds, suggesting a conformational pathway from the ligand-binding pocket to regions that interact with G proteins.

  2. 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

  3. Cannabinoid modulation of alpha2 adrenergic receptor function in rodent medial prefrontal cortex

    PubMed Central

    Cathel, Alessandra M.; Reyes, Beverly A. S.; Wang, Qin; Palma, Jonathan; Mackie, Kenneth; Bockstaele, Elisabeth J. Van; Kirby, Lynn G.

    2014-01-01

    Endocannabinoids acting at the cannabinoid type 1 receptor (CB1R) are known to regulate attention, cognition and mood. Previous studies have shown that, in the rat medial prefrontal cortex (mPFC), CB1R agonists increase norepinephrine release, an effect that may be attributed, in part, to CB1Rs localized to noradrenergic axon terminals. The present study was aimed at further characterizing functional interactions between CB1R and adrenergic receptor (AR) systems in the mPFC using in-vitro intracellular electrophysiology and high-resolution neuroanatomical techniques. Whole-cell patch-clamp recordings of layer V/VI cortical pyramidal neurons in rats revealed that both acute and chronic treatment with the synthetic CB1R agonist WIN 55,212-2 blocked elevations in cortical pyramidal cell excitability and increases in input resistance evoked by the α2-adrenergic receptor (α2-AR) agonist clonidine, suggesting a desensitization of α2-ARs. These CB1R–α2-AR interactions were further shown to be both action potential- and gamma-aminobutyric acid-independent. To better define sites of cannabinoid–AR interactions, we localized α2A-ARs in a genetically modified mouse that expressed a hemoagglutinin (HA) tag downstream of the α2A-AR promoter. Light and electron microscopy indicated that HA-α2A-AR was distributed in axon terminals and somatodendritic processes especially in layer V of the mPFC. Triple-labeling immunocytochemistry revealed that α2A-AR and CB1R were localized to processes that contained dopamine-β-hydroxylase, a marker of norepinephrine. Furthermore, HA-α2A-AR was localized to processes that were directly apposed to CB1R. These findings suggest multiple sites of interaction between cortical cannabinoid–adrenergic systems that may contribute to understanding the effect of cannabinoids on executive functions and mood. PMID:25131562

  4. 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.

  5. 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.

  6. Altered beta-adrenergic receptor-stimulated cAMP formation in cultured skin fibroblasts from Alzheimer donors.

    PubMed

    Huang, H M; Gibson, G E

    1993-07-15

    An alteration in signal transduction systems in Alzheimer's disease would likely be of pathophysiological significance, because these steps are critical to normal brain function. Since dynamic processes are difficult to study in autopsied brain, the current studies utilized cultured skin fibroblasts. The beta-adrenergic-stimulated increase in cAMP was reduced approximately 80% in fibroblasts from Alzheimer's disease compared with age-matched controls. The deficit in Alzheimer fibroblasts in response to various adrenergic agonists paralleled their beta-adrenergic potency, and enhancement of cAMP accumulation by a non-adrenergic agonist, such as prostaglandin E1, was similar in Alzheimer and control fibroblasts. Diminished adenylate cyclase activity did not underlie these abnormalities, since direct stimulation of adenylate cyclase by forskolin elevated cAMP production equally in Alzheimer and control fibroblasts. Cholera toxin equally stimulated cAMP formation in Alzheimer and control fibroblasts. Moreover, cholera toxin partially reduced isoproterenol-induced cAMP deficit in Alzheimer fibroblasts. Pertussis toxin, on the other hand, did not alter the Alzheimer deficits. The results suggest either that the coupling of the GTP-binding protein(s) to the beta-adrenergic receptor is abnormal or that the sensitivity of receptor is altered with Alzheimer's disease. Further, any hypothesis about Alzheimer's disease must explain why a reduced beta-adrenergic-stimulated cAMP formation persists in tissue culture.

  7. 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.

  8. 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.

  9. 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.

  10. Endothelin receptor antagonists and cardiovascular diseases of aging.

    PubMed

    Love, M P; McMurray, J J

    2001-01-01

    Our understanding of the role of the endothelin system in human cardiovascular physiology and pathophysiology has evolved very rapidly since the initial description of its constituent parts in 1988. Endothelin-1 (ET-1) is the predominant endothelin isoform in the human cardiovascular system and has potent vasoconstrictor, mitogenic and antinatriuretic properties which have implicated it in the pathophysiology of a number of cardiovascular diseases. The effects of ET-1 have been shown to be mediated by 2 principal endothelin receptor subtypes: ET(A) and ET(B). The development of a range of peptidic and nonpeptidic endothelin receptor antagonists represents an exciting breakthrough in human cardiovascular therapeutics. Two main classes of endothelin receptor antagonist have been developed for possible human therapeutic use: ET(A)-selective and nonselective antagonists. Extensive laboratory and clinical research with these agents has highlighted their promise in various cardiovascular diseases. Randomised, placebo-controlled clinical trials have yielded very encouraging results in patients with hypertension and chronic heart failure with more preliminary data suggesting a possible role in the treatment and prevention of atherosclerosis and stroke. Much more research is needed, however, before endothelin receptor antagonists can be considered for clinical use.

  11. Novel benzopolycyclic amines with NMDA receptor antagonist activity.

    PubMed

    Valverde, Elena; Sureda, Francesc X; Vázquez, Santiago

    2014-05-01

    A new series of benzopolycyclic amines active as NMDA receptor antagonists were synthesized. Most of them exhibited increased activity compared with related analogues previously published. All the tested compounds were more potent than clinically approved amantadine and one of them displayed a lower IC50 value than memantine, an anti-Alzheimer's approved drug.

  12. [Medical economics evaluation of 5-HT3 receptor antagonist drugs].

    PubMed

    Utsunomiya, Junpei; Hirano, Shigeki; Fukui, Aiko; Funabashi, Kazuaki; Deguchi, Yuko; Yamada, Susumu; Naito, Kazuyuki

    2010-10-01

    At Komaki City Hospital, the drug cost in connection with cancer chemotherapy was re-examined as part of improved management along with the introduction of DPC in July 2008. With due attention to the 5-HT3 receptor antagonists, both the change from injections to oral drugs and the change from brand-name drugs to generic drugs were tried between July 2008 and June 2009. After that, in order to examine the economic impact of these changes, we investigated and analyzed the number of medications, the cost of medicine purchased, and the average drug cost per medication of the 5-HT3 receptor antagonists between April 2008 and September 2009. As a result, the cost of 5-HT3 receptor antagonists purchased decreased greatly, and the impact of the improvement was mainly due to the change to oral drugs, and partially to the change to generic drugs. Therefore, from the viewpoint of hospital economic improvement in DPC, it was thought that the change to oral drugs(5-HT3 receptor antagonists)is given top priority.

  13. 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.

  14. Changes in number of alpha-adrenergic receptor subtypes in hepatocytes from rats fed 3'-methyl-4-dimethylaminoazobenzene.

    PubMed

    Miyamoto, K; Sanae, F; Kohei, K; Nomura, M; Koshiura, R

    1990-01-01

    Changes in numbers of alpha 1- and alpha 2-adrenergic receptors in the plasma membranes of hepatocytes from female Donryu rats given feed containing 0.06% of the carcinogen 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB), were examined. alpha 1-Adrenergic receptors, measured in terms of [3H]prazosin binding, decreased to half of the control 2 weeks after the start of this diet, then gradually decreased for the next 22 weeks. alpha 2-Adrenergic receptors, measured in terms of [3H]clonidine binding, transiently increased 3-fold over the control at 2 weeks. These changes in the early period of the 3'-MeDAB diet intake may be related to hepatocarcinogenesis.

  15. 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.

  16. Stimulation of β₂-adrenergic receptors inhibits calcineurin activity in CD4(+) T cells via PKA-AKAP interaction.

    PubMed

    Riether, Carsten; Kavelaars, Annemieke; Wirth, Timo; Pacheco-López, Gustavo; Doenlen, Raphael; Willemen, Hanneke; Heijnen, Cobi J; Schedlowski, Manfred; Engler, Harald

    2011-01-01

    The sympathetic nervous system (SNS) is able to modulate immune functions via adrenoceptor-dependent mechanisms. Activation of β₂-adrenergic receptors (AR) on CD4(+) T lymphocytes has been shown to inhibit Th1-cytokine production and cell proliferation. Here, we investigated the role of the calcium/calmodulin-dependent protein phosphatase calcineurin (CaN), a key element of the T cell receptor (TCR)-signaling pathway, in β₂-AR-mediated suppression of T cell function. Purified rat splenic CD4(+) T cells were stimulated with anti-CD3/anti-CD28 in presence or absence of the β₂-AR agonist terbutaline (TERB). Treatment with TERB induced a dose-dependent inhibition of cellular CaN activity, along with a reduction in IL-2 and IFN-γ production, and T cell proliferation. Co-administration of the β-AR antagonist nadolol abolished these effects. Blockade of the cAMP-dependent protein kinase A (PKA) with the inhibitor H-89 completely prevented TERB-induced CaN inhibition. However, a receptor-independent rise in the second messenger cAMP was not sufficient to suppress CaN activity. Disruption of the interaction between PKA and A-kinase anchoring protein (AKAP) by the inhibitor peptide St-Ht31 fully blocked TERB-induced CaN inhibition, demonstrating that PKA-AKAP interaction is essential for the β₂-AR-mediated CaN inhibition. Taken together, this study provides evidence for a link between the β₂-AR and TCR signaling pathways since expression of IL-2 and IFN-γ in activated T cells largely depends on dephosphorylation of the transcription factor NFAT by CaN, and identifies a novel intracellular mechanism that can lead to downregulation of T cell function after SNS activation.

  17. In silico screening for agonists and blockers of the β2 adrenergic receptor: implications of inactive and activated state structures

    PubMed Central

    Costanzi, Stefano; Vilar, Santiago

    2011-01-01

    Ten crystal structures of the β2 adrenergic receptor (β2AR) have been published, reflecting different signaling states. Here, through controlled docking experiments, we examined the implications of using inactive or activated structures on the in silico screening for agonists and blockers of the receptor. Specifically, we targeted the crystal structures solved in complex with carazolol (2RH1), the neutral antagonist alprenalol (3NYA), the irreversible agonist FAUC50 (3PDS) and the full agonist BI-167017 (3P0G). Our results indicate that activated structures favor agonists over blockers while inactive structures favor blockers over agonists. This tendency is more marked for activated than for inactive structures. Additionally, agonists tend to receive more favorable docking scores when docked at activated rather than inactive structures, while blockers do the opposite. Hence, the difference between the docking scores attained with an activated and an inactive structure is an excellent means for the classification of ligands into agonists and blockers, as we determined through receiver operating characteristic (ROC) curves and linear discriminant analysis (LDA). With respect to virtual screening, all structures prioritized well agonists and blockers over non-binders. However, inactive structures worked better for blockers and activated structures worked better for agonists. Notably, the combination of individual docking experiments through receptor ensemble docking (RED) resulted in an excellent performance in the retrieval of both agonists and blockers. Finally, we demonstrated that the induced fit docking of agonists is a viable way of modifying an inactive crystal structure and bias it towards the in silico recognition of agonists rather than blockers. PMID:22170280

  18. Cold Exposure Induces Proliferation of Mature Brown Adipocyte in a ß3-Adrenergic Receptor-Mediated Pathway

    PubMed Central

    Fukano, Keigo; Okamatsu-Ogura, Yuko; Tsubota, Ayumi; Nio-Kobayashi, Junko; Kimura, Kazuhiro

    2016-01-01

    Hyperplasia of brown adipose tissue (BAT) is a fundamental mechanism for adaptation to survive in the cold environment in rodents. To determine which cell types comprising BAT contribute to tissue hyperplasia, immunohistochemical analysis using a proliferative marker Ki67 was performed on the BAT from 6-week-old C57BL/6J mice housed at 23°C (control) or 10°C (cold) for 5 days. Interestingly, in the control group, the cell proliferative marker Ki67 was detected in the nuclei of uncoupling protein 1-positive mature brown adipocytes (7.2% ± 0.4% of brown adipocyte), as well as in the non-adipocyte stromal-vascular (SV) cells (19.6% ± 2.3% of SV cells), which include preadiopocytes. The percentage of Ki67-positive brown adipocytes increased to 25.6% ± 1.8% at Day 1 after cold exposure and was significantly higher than the non-cold acclimated control until Day 5 (21.8% ± 1.7%). On the other hand, the percentage of Ki67-positive SV cells gradually increased by a cold exposure and peaked to 42.1% ± 8.3% at Day 5. Injection of a ß3-adrenergic receptor (ß3-AR) agonist for continuous 5 days increased the number of Ki67-positive brown adipocytes even at Day 1 but not that of SV cells. In addition, the ß3-AR antagonist, but not ß1-AR antagonist, attenuated the cold exposure-induced increase in the number of Ki67-positive brown adipocytes. These results suggest that mature brown adipocytes proliferate immediately after cold exposure in a ß3-AR-mediated pathway. Thus, proliferation of mature brown adipocytes as well as preadipocytes in SV cells may contribute to cold exposure-induced BAT hyperplasia. PMID:27846311

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

    PubMed Central

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

    2015-01-01

    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

  20. Role of selective alpha and beta adrenergic receptor mechanisms in rat jejunal longitudinal muscle contractility.

    PubMed

    Seiler, Roland; Rickenbacher, Andreas; Shaw, Sidney; Haefliger, Simon; Balsiger, Bruno M

    2008-06-01

    Gut motility is modulated by adrenergic mechanisms. The aim of our study was to examine mechanisms of selective adrenergic receptors in rat jejunum. Spontaneous contractile activity of longitudinal muscle strips from rat jejunum was measured in 5-ml tissue chambers. Dose-responses (six doses, 10(-7) -3 x 10(-5)M) to norepinephrine (NE, nonspecific), phenylephrine (PH, alpha1), clonidine (C, alpha2), prenalterol (PR, beta1), ritodrine (RI, beta2), and ZD7714 (ZD, beta3) were evaluated with and without tetrodotoxin (TTX, nerve blocker). NE(3 x 10(-5)M) inhibited 74 +/- 5% (mean +/- SEM) of spontaneous activity. This was the maximum effect. The same dose of RI(beta2), PH(alpha1), or ZD(beta(3)) resulted in an inhibition of only 56 +/- 5, 43 +/- 4, 33 +/- 6, respectively. The calculated concentration to induce 50% inhibition (EC50) of ZD(beta3) was similar to NE, whereas higher concentrations of PH(alpha1) or RI(beta2) were required. C(alpha2) and PR(beta1) had no effect. TTX changed exclusively the EC50 of RI from 4.4 +/- 0.2 to 2.7 +/- 0.8% (p < 0.04). Contractility was inhibited by NE (nonspecific). PH(alpha1), RI(beta2), and ZD(beta3) mimic the effect of NE. TTX reduced the inhibition by RI. Our results suggest that muscular alpha1, beta2, and beta3 receptor mechanisms mediate adrenergic inhibition of contractility in rat jejunum. beta2 mechanisms seem to involve also neural pathways.

  1. Small molecule antagonists for chemokine CCR3 receptors.

    PubMed

    Willems, Lianne I; Ijzerman, Ad P

    2010-09-01

    The chemokine receptor CCR3 is believed to play a role in the development of allergic diseases such as asthma, atopic dermatitis, and allergic rhinitis. Despite the conflicting results that have been reported regarding the importance of eosinophils and CCR3 in allergic inflammation, inhibition of this receptor with small molecule antagonists is thought to provide a valuable approach for the treatment of these diseases. This review describes the structure-activity relationships (SAR) of small molecule CCR3 antagonists as reported in the scientific and patent literature. Various chemical classes of small molecule CCR3 antagonists have been described so far, including (bi)piperidine and piperazine derivatives, N-arylalkylpiperidine urea derivatives and (N-ureidoalkyl)benzylpiperidines, phenylalanine derivatives, morpholinyl derivatives, pyrrolidinohydroquinazolines, arylsulfonamides, amino-alkyl amides, imidazole- and pyrimidine-based antagonists, and bicyclic diamines. The (N-ureidoalkyl)benzylpiperidines are the best studied class in view of their generally high affinity and antagonizing potential. For many of these antagonists subnanomolar IC(50) values were reported for binding to CCR3 along with the ability to effectively inhibit intracellular calcium mobilization and eosinophil chemotaxis induced by CCR3 agonist ligands in vitro.

  2. Pharmacological Characterization of a Novel Beta 3 Adrenergic Agonist, Vibegron: Evaluation of Antimuscarinic Receptor Selectivity for Combination Therapy for Overactive Bladder.

    PubMed

    Di Salvo, J; Nagabukuro, H; Wickham, L A; Abbadie, C; DeMartino, J A; Fitzmaurice, A; Gichuru, L; Kulick, A; Donnelly, M J; Jochnowitz, N; Hurley, A L; Pereira, A; Sanfiz, A; Veronin, G; Villa, K; Woods, J; Zamlynny, B; Zycband, E; Salituro, G M; Frenkl, T; Weber, A E; Edmondson, S D; Struthers, M

    2017-02-01

    Although the physiologic role of muscarinic receptors in bladder function and the therapeutic efficacy of muscarinic antagonists for the treatment of overactive bladder are well established, the role of β3-adrenergic receptors (β3ARs) and their potential as therapeutics is just emerging. In this manuscript, we characterized the pharmacology of a novel β3AR agonist vibegron (MK-4618, KRP-114V) and explored mechanistic interactions of β3AR agonism and muscarinic antagonism in urinary bladder function. Vibegron is a potent, selective full β3AR agonist across species, and it dose dependently increased bladder capacity, decreased micturition pressure, and increased bladder compliance in rhesus monkeys. The relaxation effect of vibegron was enhanced when combined with muscarinic antagonists, but differentially influenced by muscarinic receptor subtype selectivity. The effect was greater when vibegron was co-administered with tolterodine, a nonselective antagonist, compared with coadministration with darifenacin, a selective M3 antagonist. Furthermore, a synergistic effect for bladder strip relaxation was observed with the combination of a β3AR agonist and tolterodine in contrast to simple additivity with darifenacin. To determine expression in rhesus bladder, we employed a novel β3AR agonist probe, [(3)H]MRL-037, that selectively labels β3 receptors in both urothelium and detrusor smooth muscle. Vibegron administration caused a dose-dependent increase in circulating glycerol and fatty acid levels in rhesus and rat in vivo, suggesting these circulating lipids can be surrogate biomarkers. The translation of our observation to the clinic has yet to be determined, but the combination of β3AR agonists with M2/M3 antimuscarinics has the potential to redefine the standard of care for the pharmacological treatment of overactive bladder.

  3. Circadian-related heteromerization of adrenergic and dopamine D₄ receptors modulates melatonin synthesis and release in the pineal gland.

    PubMed

    González, Sergio; Moreno-Delgado, David; Moreno, Estefanía; Pérez-Capote, Kamil; Franco, Rafael; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carme; Ortiz, Jordi; Ferré, Sergi; Canela, Enric; McCormick, Peter J

    2012-01-01

    The role of the pineal gland is to translate the rhythmic cycles of night and day encoded by the retina into hormonal signals that are transmitted to the rest of the neuronal system in the form of serotonin and melatonin synthesis and release. Here we describe that the production of both melatonin and serotonin by the pineal gland is regulated by a circadian-related heteromerization of adrenergic and dopamine D₄ receptors. Through α(₁B)-D₄ and β₁-D₄ receptor heteromers dopamine inhibits adrenergic receptor signaling and blocks the synthesis of melatonin induced by adrenergic receptor ligands. This inhibition was not observed at hours of the day when D₄ was not expressed. These data provide a new perspective on dopamine function and constitute the first example of a circadian-controlled receptor heteromer. The unanticipated heteromerization between adrenergic and dopamine D₄ receptors provides a feedback mechanism for the neuronal hormone system in the form of dopamine to control circadian inputs.

  4. 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

  5. Cloning of the cDNA for the human. beta. /sub 1/-adrenergic receptor

    SciTech Connect

    Frielle, T.; Collins, S.; Daniel, K.W.; Caron, M.G.; Lefkowitz, R.J.; Kobilka, B.K.

    1987-11-01

    Screening of a human placenta lambdagt11 library has led to the isolation of the cDNA for the human ..beta../sub 1/-adrenergic receptor (..beta../sub 1/AR). Used as the probe was the human genomic clone termed G-21. This clone, which contains an intronless gene for a putative receptor, was previously isolated by virtue of its cross hybridization with the human ..beta../sub 2/-adrenergic receptor (..beta../sub 2/AR). The 2.4-kilobase cDNA for the human ..beta../sub 1/AR encodes a protein of 477 amino acid residues that is 69% homologous with the avian ..beta..AR but only 54% homologous with the human ..beta../sub 2/AR. This suggests that the avian gene encoding ..beta..AR and the human gene encoding ..beta../sub 1/AR evolved from a common ancestral gene. RNA blot analysis indicates a message of 2.5 kilobases in rat tissues, with a pattern of tissue distribution consistent with ..beta../sub 1/AR binding. This pattern is quite distinct from the pattern obtained when the ..beta../sub 2/AR cDNA is used as a probe. Expression of receptor protein in Xenopus laevis oocytes conveys adenylate cyclase responsiveness to catecholamines with a typical ..beta../sub 1/AR specificity. This contrasts with the typical ..beta../sub 2/ subtype specificity observed when the human ..beta../sub 2/AR cDNA is expressed in this system. Mammalian ..beta../sub 1/AR and ..beta../sub 2/AR are thus products of distinct genes, both of which are apparently related to the putative G-21 receptor.

  6. Src regulates sequence-dependent beta-2 adrenergic receptor recycling via cortactin phosphorylation.

    PubMed

    Vistein, Rachel; Puthenveedu, Manojkumar A

    2014-11-01

    The recycling of internalized signaling receptors, which has direct functional consequences, is subject to multiple sequence and biochemical requirements. Why signaling receptors recycle via a specialized pathway, unlike many other proteins that recycle by bulk, is a fundamental unanswered question. Here, we show that these specialized pathways allow selective control of signaling receptor recycling by heterologous signaling. Using assays to visualize receptor recycling in living cells, we show that the recycling of the beta-2 adrenergic receptor (B2AR), a prototypic signaling receptor, is regulated by Src family kinases. The target of Src is cortactin, an essential factor for B2AR sorting into specialized recycling microdomains on the endosome. Phosphorylation of a single cortactin residue, Y466, regulates the rate of fission of B2AR recycling vesicles from these microdomains and, therefore, the rate of delivery of B2AR to the cell surface. Together, our results indicate that actin-stabilized microdomains that mediate signaling receptor recycling can serve as a functional point of convergence for crosstalk between signaling pathways.

  7. Sex mediates dopamine and adrenergic receptor expression in adult rats exposed prenatally to cocaine

    PubMed Central

    Ferris, Mark J.; Mactutus, Charles F.; Silvers, Janelle M.; Hasselrot, Ulla; Strupp, Barbara J.; Booze, Rosemarie M.

    2010-01-01

    The extent of catecholaminergic receptor and respective behavioral alterations associated with prenatal cocaine exposure varies according to exogenous factors such as the amount, frequency, and route of maternal exposure, as well as endogenous factors such as specific brain regions under consideration and sex of the species. The goal of the current study was to use autoradiography to delineate possible moderators of dopaminergic and adrenergic receptor expression in adult rat offspring exposed to cocaine in utero. The current study demonstrated sex-dependent D1 receptor, α2, and noradrenergic transporter binding alterations in prelimbic, hippocampus, and anterior cingulate regions of adult rat brains exposed to cocaine during gestational days 8–21. Of further interest was the lack of alterations in the nucleus accumbens for nearly all receptors/transporters investigated, as well as the lack of alterations in D3 receptor binding in nearly all of the regions investigated (nucleus accumbens, prelimbic region, hippocampus, and cingulate gyrus). Thus, the current investigation demonstrated persistent receptor and transporter alterations that extend well into adulthood as a result of cocaine exposure in utero. Furthermore, the demonstration that sex played a mediating role in prenatal cocaine-induced, aberrant receptor/transporter expression is of primary importance for future studies that seek to control for sex in either design or analysis. PMID:17933484

  8. Scaffold variations in amine warhead of histamine H₃ receptor antagonists.

    PubMed

    Wingen, Kerstin; Stark, Holger

    2013-12-01

    The histamine H₃ receptor (H₃R) is involved in numerous regulatory neurotransmission processes and there-fore, is a prominent target for centrally occurring disease with some promising clinical candidates. Previous research resulted in the identification of a core pharmacophore blueprint for H₃R antagonists/inverse agonists, which when inserted in a molecule, mostly ensures acceptable affinity. Nevertheless, variations of scaffold and peripheral areas can increase potency and pharmacokinetic profile of drug candidates. The variations in amine scaffolds of antagonists for this aminergic GPCR are of special importance.

  9. Mirtazapine, but not fluvoxamine, normalizes the blunted REM sleep response to clonidine in depressed patients: implications for subsensitivity of alpha(2)-adrenergic receptors in depression.

    PubMed

    Schittecatte, Michel; Dumont, Françoise; Machowski, Robert; Fontaine, Eric; Cornil, Catherine; Mendlewicz, Julien; Wilmotte, Jean

    2002-01-31

    To determine whether alpha(2)-adrenergic receptor (alpha2AR) subsensitivity is a state or a trait marker of depression, we consecutively challenged 32 drug-free depressed patients with a clonidine REM suppression test (CREST). We then treated the patients with fluvoxamine, a selective serotonin reuptake inhibitor, or mirtazapine, a selective alpha(2)-adrenergic receptor antagonist. The first 10 patients from each treatment group who recovered were given a second challenge test. The CREST values of the two treatment groups at each time point were compared, and also compared with the CREST values of a group of 10 normal subjects. Before treatment, the REM sleep response to clonidine in the two groups of patients was significantly blunted compared with the REM sleep response in the healthy subjects. After treatment, there was still an abnormal REM sleep response to clonidine in the fluvoxamine-treated patients, despite clinical recovery, but there was a normalized REM sleep response in the mirtazapine-treated patients. These results are compatible with the hypothesis that alpha2AR subsensitivity is a trait marker of depression and suggest that the effects of these two antidepressants on alpha2AR sensitivity may not be linked to the alleviation of depression.

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

    PubMed Central

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

    2016-01-01

    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

  11. [Genetic polymorphism of beta-adrenergic receptors and mortality in ischemic heart disease].

    PubMed

    Jaillon, Patrice; Simon, Tabassome

    2007-01-01

    The genetic polymorphism of beta-2 adrenergic receptors (B2AR) could play a major role in the prognostic of patients with a coronary heart disease. Two recent epidemiological studies could support this hypothesis. In 597 patients treated by a beta-blocker and followed for 3 years after a myocardial infarction or an acute coronary syndrome, the death rate was 5.4 times higher in homozygous Arg 16 and Gln 27 B2AR genotypes than in heterozygous or homozygous Gly 16 and Glu 27 B2AR genotypes. The beta-1 adrenergic receptor (B1AR) genetic polymorphism did not modify mortality. In a second study, in a prospective cohort of 5249 patients aged > or =65 years, the incidence of sudden cardiac death was 1.56 times higher in patients with homozygous Gln 27 B2AR than in heterozygous or homozygous Glu 27 B2AR genotype. This result was confirmed by a case-control study (155 cases of sudden cardiac death versus 144 control subjects). These data suggest that B2AR genetic polymorphism should be systematically studied in clinical trials in myocardial ischemia, with or without congestive heart failure.

  12. 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.

  13. Alpha-1 adrenergic receptors gate rapid orientation-specific reduction in visual discrimination.

    PubMed

    Treviño, Mario; Frey, Sebastian; Köhr, Georg

    2012-11-01

    Prolonged imbalance in sensory experience leads to dramatic readjustments in cortical representation. Neuromodulatory systems play a critical role in habilitating experience-induced plasticity and regulate memory processes in vivo. Here, we show that a brief period of intense patterned visual stimulation combined with systemic activation of alpha-1 adrenergic neuromodulator receptors (α(1)-ARs) leads to a rapid, reversible, and NMDAR-dependent depression of AMPAR-mediated transmission from ascending inputs to layer II/III pyramidal cells in the visual cortex of young and adult mice. The magnitude of this form of α(1)-AR long-term depression (LTD), measured ex vivo with miniature EPSC recordings, is graded by the number of orientations used during visual experience. Moreover, behavioral tests of visual function following the induction of α(1)-AR LTD reveal that discrimination accuracy of sinusoidal drifting gratings is selectively reduced at high spatial frequencies in a reversible, orientation-specific, and NMDAR-dependent manner. Thus, α(1)-ARs enable rapid cortical synaptic depression which correlates with an orientation-specific decrease in visual discrimination. These findings contribute to our understanding of how adrenergic receptors interact with neuronal networks in response to changes in active sensory experience to produce adaptive behavior.

  14. Alpha-1 Adrenergic Receptors Gate Rapid Orientation-Specific Reduction in Visual Discrimination

    PubMed Central

    Frey, Sebastian; Köhr, Georg

    2012-01-01

    Prolonged imbalance in sensory experience leads to dramatic readjustments in cortical representation. Neuromodulatory systems play a critical role in habilitating experience-induced plasticity and regulate memory processes in vivo. Here, we show that a brief period of intense patterned visual stimulation combined with systemic activation of alpha-1 adrenergic neuromodulator receptors (α1-ARs) leads to a rapid, reversible, and NMDAR-dependent depression of AMPAR-mediated transmission from ascending inputs to layer II/III pyramidal cells in the visual cortex of young and adult mice. The magnitude of this form of α1-AR long-term depression (LTD), measured ex vivo with miniature EPSC recordings, is graded by the number of orientations used during visual experience. Moreover, behavioral tests of visual function following the induction of α1-AR LTD reveal that discrimination accuracy of sinusoidal drifting gratings is selectively reduced at high spatial frequencies in a reversible, orientation-specific, and NMDAR-dependent manner. Thus, α1-ARs enable rapid cortical synaptic depression which correlates with an orientation-specific decrease in visual discrimination. These findings contribute to our understanding of how adrenergic receptors interact with neuronal networks in response to changes in active sensory experience to produce adaptive behavior. PMID:22120418

  15. 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.

  16. Differential expression and role of hyperglycemia induced oxidative stress in epigenetic regulation of β1, β2 and β3-adrenergic receptors in retinal endothelial cells

    PubMed Central

    2014-01-01

    Background Aberrant epigenetic profiles are concomitant with a spectrum of developmental defects and diseases. Role of methylation is an increasingly accepted factor in the pathophysiology of diabetes and its associated complications. This study aims to examine the correlation between oxidative stress and methylation of β1, β2 and β3-adrenergic receptors and to analyze the differential variability in the expression of these genes under hyperglycemic conditions. Methods Human retinal endothelial cells were cultured in CSC complete medium in normal (5 mM) or high (25 mM) glucose to mimic a diabetic condition. Reverse transcription PCR and Western Blotting were performed to examine the expression of β1, β2 and β3-adrenergic receptors. For detections, immunocytochemistry was used. Bisulfite sequencing method was used for promoter methylation analysis. Apoptosis was determined by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Dichlorodihydrofluorescein diacetate (DCFH-DA) assay was used to measure reactive oxygen species (ROS) production in the cells. Results β1 and β3-adrenergic receptors were expressed in retinal endothelial cells while β2-adrenergic receptor was not detectable both at protein and mRNA levels. Hyperglycemia had no significant effect on β1 and β2-adrenergic receptors methylation and expression however β3-adrenergic receptors showed a significantly higher expression (p < 0.05) and methylation (p < 0.01) in high and low glucose concentration respectively. Apoptosis and oxidative stress were inversely correlated with β3-adrenergic receptors methylation with no significant effect on β1 and β2-adrenergic receptors. β2-adrenergic receptor was hypermethylated with halted expression. Conclusion Our study demonstrates that β1 and β3-adrenergic receptors expressed in human retinal endothelial cells. Oxidative stress and apoptosis are inversely proportional to the extent of promoter methylation

  17. Adrenergic receptor polymorphisms and autonomic nervous system function in human obesity.

    PubMed

    Yasuda, Koichiro; Matsunaga, Tetsuro; Adachi, Tetsuya; Aoki, Norihiko; Tsujimoto, Gozoh; Tsuda, Kinsuke

    2006-09-01

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

  18. α2 Adrenergic Receptor Trafficking as a Therapeutic Target in Antidepressant Drug Action.

    PubMed

    Cottingham, Christopher; Ferryman, Craig J; Wang, Qin

    2015-01-01

    Antidepressant drugs remain poorly understood, especially with respect to pharmacological mechanisms of action. This lack of knowledge results from the extreme complexity inherent to psychopharmacology, as well as to a corresponding lack of knowledge regarding depressive disorder pathophysiology. While the final analysis is likely to be multifactorial and heterogeneous, compelling evidence exists for upregulation of brain α2 adrenergic receptors (ARs) in depressed patients. This evidence has sparked a line of research into actions of a particular antidepressant drug class, the tricyclic antidepressants (TCAs), as direct ligands at α(2A)ARs. Our findings, as outlined herein, demonstrate that TCAs function as arrestin-biased ligands at α(2A)ARs. Importantly, TCA-induced α(2A)AR/arrestin recruitment leads to receptor endocytosis and downregulation of α(2A)AR expression with prolonged exposure. These findings represent a novel mechanism linking α(2)AR trafficking with antidepressant pharmacology.

  19. 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

  20. 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.

  1. Antagonistic action of pitrazepin on human and rat GABAA receptors

    PubMed Central

    Demuro, Angelo; Martinez-Torres, Ataulfo; Francesconi, Walter; Miledi, Ricardo

    1999-01-01

    Pitrazepin, 3-(piperazinyl-1)-9H-dibenz(c,f) triazolo(4,5-a)azepin is a piperazine antagonist of GABA in a variety of electrophysiological and in vitro binding studies involving GABA and glycine receptors. In the present study we have investigated the effects of pitrazepin, and the GABAA antagonist bicuculline, on membrane currents elicited by GABA in Xenopus oocytes injected with rat cerebral cortex mRNA or cDNAs encoding α1β2 or α1β2γ2S human GABAA receptor subunits.The three types of GABAA receptors expressed were reversibly antagonized by bicuculline and pitrazepin in a concentration-dependent manner. GABA dose-current response curves for the three types of receptors were shifted to the right, in a parallel manner, by increasing concentrations of pitrazepin.Schild analyses gave pA2 values of 6.42±0.62, n=4, 6.41±1.2, n=5 and 6.21±1.24, n=6, in oocytes expressing rat cerebral cortex, α1β2 or α1β2γ2S human GABAA receptors respectively (values are given as means±s.e.mean), and the Hill coefficients were all close to unity. All this is consistent with the notion that pitrazepin acts as a competitive antagonist of these GABAA receptors; and that their antagonism by pitrazepin is not strongly dependent on the subunit composition of the receptors here studied.Since pitrazepin has been reported to act also at the benzodiazepine binding site, we studied the effect of the benzodiazepine antagonist Ro 15-1788 (flumazenil) on the inhibition of α1β2γ2S receptors by pitrazepin. Co-application of Ro 15-1788 did not alter the inhibiting effect of pitrazepin. Moreover, pitrazepin did not antagonize the potentiation of GABA-currents by flunitrazepam. All this suggests that pitrazepin does not affect the GABA receptor-chloride channel by interacting with the benzodiazepine receptor site. PMID:10369456

  2. Stress-induced decrease of uterine blood flow in sheep is mediated by alpha 1-adrenergic receptors.

    PubMed

    Dreiling, Michelle; Bischoff, Sabine; Schiffner, Rene; Rupprecht, Sven; Kiehntopf, Michael; Schubert, Harald; Witte, Otto W; Nathanielsz, Peter W; Schwab, Matthias; Rakers, Florian

    2016-09-01

    Prenatal maternal stress can be transferred to the fetus via a catecholamine-dependent decrease of uterine blood flow (UBF). However, it is unclear which group of adrenergic receptors mediates this mechanism of maternal-fetal stress transfer. We hypothesized that in sheep, alpha 1-adrenergic receptors may play a key role in catecholamine mediated UBF decrease, as these receptors are mainly involved in peripheral vasoconstriction and are present in significant number in the uterine vasculature. After chronic instrumentation at 125 ± 1 days of gestation (dGA; term 150 dGA), nine pregnant sheep were exposed at 130 ± 1 dGA to acute isolation stress for one hour without visual, tactile, or auditory contact with their flockmates. UBF, blood pressure (BP), heart rate (HR), stress hormones, and blood gases were determined before and during this isolation challenge. Twenty-four hours later, experiments were repeated during alpha 1-adrenergic receptor blockage induced by a continuous intravenous infusion of urapidil. In both experiments, ewes reacted to isolation with an increase in serum norepinephrine, cortisol, BP, and HR as typical signs of activation of sympatho-adrenal and the hypothalamic-pituitary-adrenal axis. Stress-induced UBF decrease was prevented by alpha 1-adrenergic receptor blockage. We conclude that UBF decrease induced by maternal stress in sheep is mediated by alpha 1-adrenergic receptors. Future studies investigating prevention strategies of impact of prenatal maternal stress on fetal health should consider selective blockage of alpha 1-receptors to interrupt maternal-fetal stress transfer mediated by utero-placental malperfusion.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Optimization of amide-based EP3 receptor antagonists.

    PubMed

    Lee, Esther C Y; Futatsugi, Kentaro; Arcari, Joel T; Bahnck, Kevin; Coffey, Steven B; Derksen, David R; Kalgutkar, Amit S; Loria, Paula M; Sharma, Raman

    2016-06-01

    Prostaglandin E receptor subtype 3 (EP3) antagonism may treat a variety of symptoms from inflammation to cardiovascular and metabolic diseases. Previously, most EP3 antagonists were large acidic ligands that mimic the substrate, prostaglandin E2 (PGE2). This manuscript describes the optimization of a neutral small molecule amide series with improved lipophilic efficiency (LipE) also known as lipophilic ligand efficiency (LLE) ((a) Nat. Rev. Drug Disc.2007, 6, 881; (b) Annu. Rep. Med. Chem.2010, 45, 380).

  9. Human glucagon receptor antagonists based on alkylidene hydrazides.

    PubMed

    Ling, Anthony; Plewe, Michael; Gonzalez, Javier; Madsen, Peter; Sams, Christian K; Lau, Jesper; Gregor, Vlad; Murphy, Doug; Teston, Kimberly; Kuki, Atsuo; Shi, Shenghua; Truesdale, Larry; Kiel, Dan; May, John; Lakis, James; Anderes, Kenna; Iatsimirskaia, Eugenia; Sidelmann, Ulla G; Knudsen, Lotte B; Brand, Christian L; Polinsky, Alex

    2002-02-25

    A series of alkylidene hydrazide derivatives containing an alkoxyaryl moiety was optimized. The resulting hydrazide-ethers were competitive antagonists at the human glucagon receptor. Pharmacokinetic experiments showed fast clearance of most of the compounds tested. A representative compound [4-hydroxy-3-cyanobenzoic acid (4-isopropylbenzyloxy-3,5-dimethoxymethylene)hydrazide] with an IC50 value of 20 nM was shown to reduce blood glucose levels in fasted rats.

  10. Effects of local alpha2-adrenergic receptor blockade on adipose tissue lipolysis during prolonged systemic adrenaline infusion in normal man.

    PubMed

    Simonsen, Lene; Enevoldsen, Lotte H; Stallknecht, Bente; Bülow, Jens

    2008-03-01

    During prolonged adrenaline infusion, lipolysis peaks within 30 min and thereafter tends to decline, and we hypothesized that the stimulation of local adipose tissue alpha2-adrenergic receptors accounts for this decline. The lipolytic effect of a prolonged intravenous adrenaline infusion combined with local infusion of the alpha2-blocker phentolamine in superficial and deep abdominal subcutaneous adipose tissue and in preperitoneal adipose tissue was studied in seven healthy subjects. The interstitial glycerol concentration in the three adipose tissue depots was measured by the microdialysis method. Regional adipose tissue blood flow was measured by the (133)Xe clearance technique. Regional glycerol output (lipolytic rate) was calculated from these measurements and simultaneous measurements of arterial glycerol concentrations. Adrenaline infusion increased lipolysis in all three depots (data previously published). Phentolamine infusion did not augment lipolysis in the subcutaneous depots while it increased the lipolytic rate in the preperitoneal depot. It is concluded that alpha2-adrenergic receptors do not have a significant effect on subcutaneous adipose tissue lipolysis during high circulating adrenaline concentrations, and the decrease in lipolysis in subcutaneous adipose tissue under prolonged adrenaline stimulation is thus not attributed to alpha2-adrenergic receptor inhibition of lipolysis. However, in the preperitoneal adipose tissue depot, alpha2-adrenergic receptor tone plays a role for the lipolytic rate obtained during prolonged adrenaline stimulation.

  11. Effect of sleep deprivation on the growth hormone response to the alpha-3 adrenergic receptor agonist, clonidine, in normal subjects.

    PubMed

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

    1997-01-01

    One night's sleep deprivation (SD) increased the growth hormone (GH) response to clonidine (20 ug/kg i.v.) in 11 normal men ( p < 0.005). This finding may indicate that SD enhances alpha-2 adrenergic receptor function or that the GH response to GH releasing factor in increased by SD.

  12. Heterocyclic acetamide and benzamide derivatives as potent and selective beta3-adrenergic receptor agonists with improved rodent pharmacokinetic profiles.

    PubMed

    Goble, Stephen D; Wang, Liping; Howell, K Lulu; Bansal, Alka; Berger, Richard; Brockunier, Linda; DiSalvo, Jerry; Feighner, Scott; Harper, Bart; He, Jiafang; Hurley, Amanda; Hreniuk, Donna; Parmee, Emma; Robbins, Michael; Salituro, Gino; Sanfiz, Anthony; Streckfuss, Eric; Watkins, Eloisa; Weber, Ann E; Struthers, Mary; Edmondson, Scott D

    2010-03-15

    A series of amide derived beta(3)-adrenergic receptor (AR) agonists is described. The discovery and optimization of several series of compounds derived from 1, is used to lay the SAR foundation for second generation beta(3)-AR agonists for the treatment of overactive bladder.

  13. Ca sup 2+ channel blockers interact with. alpha. sub 2 -adrenergic receptors in rabbit ileum

    SciTech Connect

    Homaidan, F.R.; Donowitz, M.; Wicks, J.; Cusolito, S.; El Sabban, M.E.; Weiland, G.A.; Sharp, G.W.G. Tufts Univ. School of Medicine and New England Medical Center Hospital, Boston, MA )

    1988-04-01

    An interaction between Ca{sup 2+} channel blockers and {alpha}{sub 2}-adrenergic receptors has been demonstrated in rabbit ileum by studying the effect of clonidine on active electrolyte transport, under short-circuited conditions, in the presence and absence of several Ca{sup 2+} channel blocking agents. Clonidine, verapamil, diltiazem, cadmium, and nitrendipine all decrease short-circuit current and stimulate NaCl absorption to different extents with clonidine having the largest effect. Exposure to verapamil, diltiazem, and cadmium inhibited the effects of clonidine on transport, whereas nitrendipine had no such effect. Verapamil, diltiazem, and cadmium, but not nitrendipine, also decreased the specific binding of ({sup 3}H){alpha}{sub 2}-adrenergic agents to a preparation of ileal basolateral membranes explaining the observed decrease in the transport effects of clonidine. The effective concentrations of the Ca{sup 2+} channel blockers that inhibited the effects of clonidine on transport were fairly similar to the concentrations needed to inhibit its specific binding. The displacement of clonidine by calcium channel blockers is ascribed to a nonspecific effect of these agents, although the possibility that their effects are exerted via their binding to the calcium channels is not excluded.

  14. 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.

  15. The forgotten serine. A critical role for Ser-2035.42 in ligand binding to and activation of the beta 2-adrenergic receptor.

    PubMed

    Liapakis, G; Ballesteros, J A; Papachristou, S; Chan, W C; Chen, X; Javitch, J A

    2000-12-01

    Previous work in the beta(2)-adrenergic receptor demonstrated critical interactions between Ser-204 and Ser-207 in the fifth membrane-spanning segment and the meta-OH and para-OH, respectively, of catecholamine agonists (Strader, C. D., Candelore, M. R., Hill, W. S., Sigal, I. S., and Dixon, R. A. (1989) J. Biol. Chem. 264, 13572-13578). Using the substituted cysteine accessibility method in the beta(2)-adrenergic receptor, we have found that in addition to Ser-204 and Ser-207, Ser-203 is also accessible on the surface of the binding-site crevice and is occluded by bound agonist. Mutation of Ser-203 to Ala, Val, or Cys reduced the binding affinity and adenylyl cyclase-activating potency of agonists containing a meta-OH, whereas their affinities and potencies were largely preserved by mutation of Ser-203 to Thr, which maintained an OH at this position. Thus both Ser-203 and Ser-204 appear to interact with the meta-OH of catecholamines, perhaps through a bifurcated H bond. Furthermore, the removal of the OH at position 203 led to a significant loss of affinity of antagonists with nitrogen in their heterocyclic ring structure. The greatest effect was seen with pindolol, a partial agonist, suggesting that a H bond between the heterocyclic ring and Ser-203 may play a role in partial agonism. In contrast, the affinities of antagonists such as propranolol or alprenolol, which have cyclic structures without H-bonding capability, were unaltered after mutation of Ser-203.

  16. Discovery of new muscarinic acetylcholine receptor antagonists from Scopolia tangutica

    PubMed Central

    Du, Nana; Liu, Yanfang; Zhang, Xiuli; Wang, Jixia; Zhao, Jianqiang; He, Jian; Zhou, Han; Mei, Lijuan; Liang, Xinmiao

    2017-01-01

    Scopolia tangutica (S. tangutica) is a traditional Chinese medicinal plant used for antispasmodics, anesthesia, analgesia and sedation. Its pharmacological activities are mostly associated with the antagonistic activity at muscarinic acetylcholine receptors (mAchRs) of several known alkaloids such as atropine and scopolamine. With our recent identification of four hydroxycinnamic acid amides from S. tangutica, we hypothesized that this plant may contain previously unidentified alkaloids that may also contribute to its in vivo effect. Herein, we used a bioassay-guided multi-dimension separation strategy to discover novel mAchR antagonists from S. tangutica. The core of this approach is to use label-free cell phenotypic assay to first identify active fractions, and then to guide purification of active ligands. Besides four tropanes and six cinnamic acid amides that have been previously isolated from S. tangutica, we recently identified two new tropanes, one new cinnamic acid amide, and nine other compounds. Six tropane compounds purified from S. tangutica for the first time were confirmed to be competitive antagonists of muscarinic receptor 3 (M3), including the two new ones 8 and 12 with IC50 values of 1.97 μM and 4.47 μM, respectively. Furthermore, the cinnamic acid amide 17 displayed 15-fold selectivity for M1 over M3 receptors. These findings will be useful in designing lead compounds for mAchRs and elucidating mechanisms of action of S. tangutica. PMID:28387362

  17. [5-HT3 receptor antagonist als analgetics in rheumatic diseases].

    PubMed

    Müller, W; Fiebich, B L; Stratz, T

    2006-10-01

    Various rheumatic diseases like fibromyalgia, systemic inflammatory rheumatic disorders and localized diseases, such as arthritides and activated arthroses, tendinopathies and periarthropathies, as well as trigger points can be improved considerably by treatment with the 5-HT3 receptor antagonist tropisetron. Particularly in the latter group of diseases, local injections have done surprisingly rapid analgesic action. This effect matches that of local anesthetics, but lasts considerably longer and is comparable to local injections of local anesthetics combined with corticosteroids. The action of the 5-HT3 receptor antagonists can be attributed to an antinociceptive effect that occurs at the same time as an antiphlogistic and probably also an immunosuppressive effect. Whereas an inhibited release of substance P from the nociceptors, and possibly some other neurokins as well, seems to be the most likely explanation for the antinociceptive action, the antiphlogistic effect is primarily due to an inhibited formation of various different phlogistic substances; in some conditions, like systemic inflammatory rheumatic diseases, for example, the 5-HT3 receptor antagonists may exert an immunosuppressive effect in addition to this.

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

    PubMed

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

    2007-11-21

    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.

  19. Molecular Determinants of the Human α2C-Adrenergic Receptor Temperature-Sensitive Intracellular Traffic

    PubMed Central

    Pullikuth, Ashok K.; Guidry, Jessie J.

    2015-01-01

    The human α2C-adrenergic receptor (α2C-AR) is localized intracellularly at physiologic temperature. Decreasing the environmental temperature strongly stimulates the receptor transport to the cell surface. In contrast, rat and mouse α2C-AR plasma membrane levels are less sensitive to decrease in temperature, whereas the opossum α2C-AR cell surface levels are not changed in these conditions. Structural analysis demonstrated that human α2C-AR has a high number of arginine residues in the third intracellular loop and in the C-terminus, organized as putative RXR motifs. Although these motifs do not affect the receptor subcellular localization at 37°C, deletion of the arginine clusters significantly enhanced receptor plasma membrane levels at reduced temperature. We found that this exaggerated transport of the human receptor is mediated by two functional arginine clusters, one in the third intracellular loop and one in the C-terminus. This effect is mediated by interactions with COPI vesicles, but not by 14-3-3 proteins. In rat α2C-AR, the arginine cluster from the third intracellular loop is shifted to the left due to three missing residues. Reinsertion of these residues in the rat α2C-AR restored the same temperature sensitivity as in the human receptor. Proteomic and coimmunoprecipitation experiments identified pontin as a molecule having stronger interactions with human α2C-AR compared with rat α2C-AR. Inhibition of pontin activity enhanced human receptor plasma membrane levels and signaling at 37°C. Our results demonstrate that human α2C-AR has a unique temperature-sensitive traffic pattern within the G protein–coupled receptor class due to interactions with different molecular chaperones, mediated in part by strict spatial localization of specific arginine residues. PMID:25680754

  20. Targeting β3-Adrenergic Receptors in the Heart: Selective Agonism and β-Blockade

    PubMed Central

    Cannavo, Alessandro

    2017-01-01

    Abstract: Cardiac diseases, such as heart failure, remain leading causes of morbidity and mortality worldwide, with myocardial infarction as the most common etiology. HF is characterized by β-adrenergic receptor (βAR) dysregulation that is primarily due to the upregulation of G protein–coupled receptor kinases that leads to overdesensitization of β1 and β2ARs, and this clinically manifests as a loss of inotropic reserve. Interestingly, the “minor” βAR isoform, the β3AR, found in the heart, lacks G protein–coupled receptor kinases recognition sites, and is not subject to desensitization, and as a consequence of this, in human failing myocardium, the levels of this receptor remain unchanged or are even increased. In different preclinical studies, it has been shown that β3ARs can activate different signaling pathways that can protect the heart. The clinical relevance of this is also supported by the effects of β-blockers which are well known for their proangiogenic and cardioprotective effects, and data are emerging showing that these are mediated, at least in part, by enhancement of β3AR activity. In this regard, targeting of β3ARs could represent a novel potential strategy to improve cardiac metabolism, function, and remodeling. PMID:28170359

  1. Mechanism of allosteric regulation of β2-adrenergic receptor by cholesterol

    PubMed Central

    Manna, Moutusi; Niemelä, Miia; Tynkkynen, Joona; Javanainen, Matti; Kulig, Waldemar; Müller, Daniel J; Rog, Tomasz; Vattulainen, Ilpo

    2016-01-01

    There is evidence that lipids can be allosteric regulators of membrane protein structure and activation. However, there are no data showing how exactly the regulation emerges from specific lipid-protein interactions. Here we show in atomistic detail how the human β2-adrenergic receptor (β2AR) – a prototypical G protein-coupled receptor – is modulated by cholesterol in an allosteric fashion. Extensive atomistic simulations show that cholesterol regulates β2AR by limiting its conformational variability. The mechanism of action is based on the binding of cholesterol at specific high-affinity sites located near the transmembrane helices 5–7 of the receptor. The alternative mechanism, where the β2AR conformation would be modulated by membrane-mediated interactions, plays only a minor role. Cholesterol analogues also bind to cholesterol binding sites and impede the structural flexibility of β2AR, however cholesterol generates the strongest effect. The results highlight the capacity of lipids to regulate the conformation of membrane receptors through specific interactions. DOI: http://dx.doi.org/10.7554/eLife.18432.001 PMID:27897972

  2. Cardiovascular pharmacogenomics of adrenergic receptor signaling: clinical implications and future directions.

    PubMed

    Johnson, J A; Liggett, S B

    2011-03-01

    G-protein-coupled receptors (GPCRs) are the targets for many drugs, and genetic variation in coding and noncoding regions is apparent in many such receptors. In this superfamily, adrenergic receptors (ARs) were among the first in which single-nucleotide polymorphisms (SNPs) were discovered, and studies including in vitro mutagenesis, genetically modified mouse models, human ex vivo and in vitro studies and pharmacogenetic association studies were conducted. The signal transduction in these receptors includes amplification steps, desensitization, crosstalk, and redundancies, enabling potential mitigation of the size of the clinical effect for a single variant in a single gene. Nevertheless, convincing evidence has emerged that several variants have an impact on therapy, with certain caveats as to how the results are to be interpreted. Here we review these results for selected ARs and associated regulatory kinases relative to the pharmacogenomics of β-blocker treatment for hypertension and heart failure. We emphasize the linking of clinical results to molecular mechanisms, discuss study design limitations, and offer some recommendations for future directions.

  3. 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.

  4. Regulation of beta-adrenergic receptor signaling by S-nitrosylation of G-protein-coupled receptor kinase 2.

    PubMed

    Whalen, Erin J; Foster, Matthew W; Matsumoto, Akio; Ozawa, Kentaro; Violin, Jonathan D; Que, Loretta G; Nelson, Chris D; Benhar, Moran; Keys, Janelle R; Rockman, Howard A; Koch, Walter J; Daaka, Yehia; Lefkowitz, Robert J; Stamler, Jonathan S

    2007-05-04

    beta-adrenergic receptors (beta-ARs), prototypic G-protein-coupled receptors (GPCRs), play a critical role in regulating numerous physiological processes. The GPCR kinases (GRKs) curtail G-protein signaling and target receptors for internalization. Nitric oxide (NO) and/or S-nitrosothiols (SNOs) can prevent the loss of beta-AR signaling in vivo, but the molecular details are unknown. Here we show in mice that SNOs increase beta-AR expression and prevent agonist-stimulated receptor downregulation; and in cells, SNOs decrease GRK2-mediated beta-AR phosphorylation and subsequent recruitment of beta-arrestin to the receptor, resulting in the attenuation of receptor desensitization and internalization. In both cells and tissues, GRK2 is S-nitrosylated by SNOs as well as by NO synthases, and GRK2 S-nitrosylation increases following stimulation of multiple GPCRs with agonists. Cys340 of GRK2 is identified as a principal locus of inhibition by S-nitrosylation. Our studies thus reveal a central molecular mechanism through which GPCR signaling is regulated.

  5. 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

  6. Discovery of high affinity ligands for β2-adrenergic receptor through pharmacophore-based high-throughput virtual screening and docking.

    PubMed

    Yakar, Ruya; Akten, Ebru Demet

    2014-09-01

    Novel high affinity compounds for human β2-adrenergic receptor (β2-AR) were searched among the clean drug-like subset of ZINC database consisting of 9,928,465 molecules that satisfy the Lipinski's rule of five. The screening protocol consisted of a high-throughput pharmacophore screening followed by an extensive amount of docking and rescoring. The pharmacophore model was composed of key features shared by all five inactive states of β2-AR in complex with inverse agonists and antagonists. To test the discriminatory power of the pharmacophore model, a small-scale screening was initially performed on a database consisting of 117 compounds of which 53 antagonists were taken as active inhibitors and 64 agonists as inactive inhibitors. Accordingly, 7.3% of the ZINC database subset (729,413 compounds) satisfied the pharmacophore requirements, along with 44 antagonists and 17 agonists. Afterwards, all these hit compounds were docked to the inactive apo form of the receptor using various docking and scoring protocols. Following each docking experiment, the best pose was further evaluated based on the existence of key residues for antagonist binding in its vicinity. After final evaluations based on the human intestinal absorption (HIA) and the blood brain barrier (BBB) penetration properties, 62 hit compounds have been clustered based on their structural similarity and as a result four scaffolds were revealed. Two of these scaffolds were also observed in three high affinity compounds with experimentally known Ki values. Moreover, novel chemical compounds with distinct structures have been determined as potential β2-AR drug candidates.

  7. 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.

  8. Increased circulating β2-adrenergic receptor autoantibodies are associated with smoking-related emphysema

    PubMed Central

    Hu, Jia-yi; Liu, Bei-bei; Du, Yi-peng; Zhang, Yuan; Zhang, Yi-wei; Zhang, You-yi; Xu, Ming; He, Bei

    2017-01-01

    Smoking is a dominant risk factor for chronic obstructive pulmonary disease (COPD) and emphysema, but not every smoker develops emphysema. Immune responses in smokers vary. Some autoantibodies have been shown to contribute to the development of emphysema in smokers. β2-adrenergic receptors (β2-ARs) are important targets in COPD therapy. β2-adrenergic receptor autoantibodies (β2-AAbs), which may directly affect β2-ARs, were shown to be increased in rats with passive-smoking-induced emphysema in our current preliminary studies. Using cigarette-smoke exposure (CS-exposure) and active-immune (via injections of β2-AR second extracellular loop peptides) rat models, we found that CS-exposed rats showed higher serum β2-AAb levels than control rats before alveolar airspaces became enlarged. Active-immune rats showed increased serum β2-AAb levels, and exhibited alveolar airspace destruction. CS-exposed-active-immune treated rats showed more extensive alveolar airspace destruction than rats undergoing CS-exposure alone. In our current clinical studies, we showed that plasma β2-AAb levels were positively correlated with the RV/TLC (residual volume/total lung capacity) ratio (r = 0.455, p < 0.001) and RV%pred (residual volume/residual volume predicted percentage, r = 0.454, p < 0.001) in 50 smokers; smokers with higher plasma β2-AAb levels exhibited worse alveolar airspace destruction. We suggest that increased circulating β2-AAbs are associated with smoking-related emphysema. PMID:28262783

  9. 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.

  10. The delta-opioid receptor is sufficient, but not necessary, for spinal opioid-adrenergic analgesic synergy.

    PubMed

    Chabot-Doré, Anne-Julie; Millecamps, Magali; Stone, Laura S

    2013-12-01

    Spinal administration of opioid and α2-adrenergic receptor (α2AR) agonists produces analgesia, and agonists interact synergistically when coadministered. The molecular mechanism underlying this synergy is largely unknown. Pharmacological studies have identified both the delta and the mu-opioid receptors (DOR and MOR) as candidate receptors capable of interacting synergistically with α2AR agonists. However, recent studies attribute the antinociceptive effect of DOR agonists to actions at the MOR, calling the role of DOR in opioid-adrenergic synergy into question. Other studies suggesting that DOR is implicated in morphine antinociception raise the possibility that DOR is nonetheless required for morphine synergy with α2AR agonists. This study aimed to determine whether DOR activation is sufficient and necessary to mediate opioid-adrenergic synergistic interactions in the spinal cord. The antinociceptive effects of clonidine, [D-Ala(2)]-deltorphin II (DeltII), morphine, and [D-Ala(2), N-Me-Phe(4), Gly-ol(5)]-enkephalin (DAMGO) were evaluated using the substance P (SP) behavioral assay in wild type (WT) and DOR-knockout (KO) mice. Opioid-adrenergic drug interactions were evaluated after spinal coadministration of clonidine with DeltII, morphine, or DAMGO. Isobolographic analyses of dose-response curves determined whether interactions were synergistic or additive. The absence of DeltII antinociceptive efficacy in DOR-KO confirmed its selectivity in the SP assay. Although DeltII+clonidine interacted synergistically in WT mice, no interaction with clonidine was observed in DOR-KO mice. Clonidine was synergistic with morphine in both mouse strains. DAMGO did not synergize with clonidine in either strain. These findings confirm that although other opioid receptors can interact synergistically with α2AR agonists, DOR is sufficient for spinal opioid-adrenergic interactions.

  11. Post-retrieval beta-adrenergic receptor blockade: effects on extinction and reconsolidation of cocaine-cue memories.

    PubMed

    Fricks-Gleason, Ashley N; Marshall, John F

    2008-09-01

    Contexts and discrete cues associated with drug-taking are often responsible for relapse among addicts. Animal models have shown that interference with the reconsolidation of drug-cue memories can reduce seeking of drugs or drug-paired stimuli. One such model is conditioned place preference (CPP) in which an animal is trained to associate a particular environment with the rewarding effects of a drug. Previous work from this laboratory has shown that intra-nucleus accumbens core infusions of a MEK inhibitor can interfere with reconsolidation of these drug-cue memories. A question that remains is whether post-retrieval drug effects on subsequent memories represent an interference with reconsolidation processes or rather a facilitation of extinction. In this experiment, we explore the effect of post-retrieval injections of propranolol, a beta-adrenergic receptor antagonist, on reconsolidation and extinction of cocaine CPP. After acquisition of cocaine CPP, animals were given post-retrieval propranolol injections once or each day during a protocol of unreinforced preference tests, until the animals showed no preference for the previously cocaine-paired environment. Following a cocaine priming injection, the animals that received daily post-test propranolol injections did not reinstate their preference for the drug-paired side. In contrast, a single post-retrieval propranolol injection followed by multiple days of unreinforced preference tests failed to blunt subsequent cocaine reinstatement of the memory. These data suggest that daily post-retrieval systemic injections of propranolol decrease the conditioned preference by interfering with reconsolidation of the memory for the association between the drug-paired side and the reinforcing effects of the drug, rather than facilitating new extinction learning.

  12. Effect of mesenchymal stem cells on hypoxia-induced desensitization of β2-adrenergic receptors in rat osteosarcoma cells

    PubMed Central

    KIDO, AKIRA; YOSHITANI, KAZUHIRO; SHIMIZU, TAKAMASA; AKAHANE, MANABU; FUJII, HIROMASA; TSUKAMOTO, SHINJI; KONDO, YUMIKO; HONOKI, KANYA; IMANO, MOTOHIRO; TANAKA, YASUHITO

    2012-01-01

    The β2-adrenergic receptor (β2AR) mediates the effects of chronic stress in several neoplasms, however, β2AR signaling is impaired by hypoxia in various tissues. While hypoxia is a common feature significant in the progression of solid tumors, little is known about the effect of hypoxia on β2AR signaling in the tumor microenvironment. Previously, it has been reported that the systemic administration of mesenchymal stem cells (MSCs) increased the engraftment and metastatic colonization of rat osteosarcoma (OS) cells. In the current study, the effect of MSCs on the hypoxia-induced desensitization of the β2AR in OS cells was investigated. Epinephrine, norepinephrine and isoproterenol increased the cellular proliferation of the rat OS cell line COS1NR and rat MSCs in a dose-dependent and β2AR antagonist-sensitive manner. While isoproterenol had significant proliferative effects on MSCs under normoxic and hypoxic conditions, COS1NR cells did not respond under hypoxic conditions. A sensitivity assay for the β2AR revealed that hypoxia impaired the sensitivity of COS1NR cells, whereas hypoxia did not affect MSCs. An immunoassay revealed no significant change in the expression of hypoxia-inducible factor-1α (HIF1α) in COS1NR cells, whilst an immunoassay demonstrated a 15% increase in MSCs following isoproterenol stimulation. In COS1NR cells co-cultured with MSCs under hypoxic conditions, isoproterenol caused a significant increase in proliferation and this effect was inhibited by an anti-interleukin (IL)-6 antibody. A tumor formation assay in syngeneic rats revealed that the systemic administration of MSCs enhances the growth of OS and the effect of MSCs was inhibited by IL-6 neutralization. In conclusion, MSCs are resistant to the hypoxia-induced desensitization to β2AR. Hypoxia caused a siginificant desensitization of the β2AR in COS1NR cells alone, whereas MSCs may support tumor progression through cellular interactions. PMID:23205094

  13. Disruption of type 5 adenylyl cyclase prevents β-adrenergic receptor cardiomyopathy: a novel approach to β-adrenergic receptor blockade.

    PubMed

    Yan, Lin; Vatner, Stephen F; Vatner, Dorothy E

    2014-11-15

    β-Adrenergic receptor (β-AR) blockade is widely used to treat heart failure, since the adverse effects of chronic β-AR stimulation are central to the pathogenesis of this disease state. Transgenic (Tg) mice, where β-AR signaling is chronically enhanced by overexpression of cardiac β₂-ARs, is a surrogate for this mechanism, since these mice develop cardiomyopathy as reflected by reduced left ventricular (LV) function, increased fibrosis, apoptosis, and myocyte hypertrophy. We hypothesized that disruption of type 5 adenylyl cyclase (AC5), which is in the β-AR signaling pathway in the heart, but exerts only a minor β-AR blocking effect, could prevent the cardiomyopathy in β₂-AR Tg mice without the negative effects of full β-AR blockade. Accordingly, we mated β₂-AR Tg mice with AC5 knockout (KO) mice. The β₂-AR Tg × AC5 KO bigenic mice prevented the cardiomyopathy as reflected by improved LV ejection fraction, reduced apoptosis, fibrosis, and myocyte size and preserved exercise capacity. The rescue was not simply due to a β-blocking effect of AC5 KO, since neither baseline LV function nor the response to isoproterenol was diminished substantially compared with the negative inotropic effects of β-blockade. However, AC5 disruption in β₂-AR Tg activates the antioxidant, manganese superoxide dismutase, an important mechanism protecting the heart from cardiomyopathy. These results indicate that disruption of AC5 prevents the cardiomyopathy induced by chronically enhanced β-AR signaling in mice with overexpressed β₂-AR, potentially by enhancing resistance to oxidative stress and apoptosis, suggesting a novel, alternative approach to β-AR blockade.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. Pharmacological Profiles of Alpha 2 Adrenergic Receptor Agonists Identified Using Genetically Altered Mice and Isobolographic Analysis

    PubMed Central

    Fairbanks, Carolyn A.; Stone, Laura S.; Wilcox, George L.

    2009-01-01

    Endogenous, descending noradrenergic fibers convey powerful analgesic control over spinal afferent circuitry mediating the rostrad transmission of pain signals. These fibers target alpha 2 adrenergic receptors (α2ARs) on both primary afferent terminals and secondary neurons, and their activation mediates substantial inhibitory control over this transmission, rivaling that of opioid receptors which share similar a similar pattern of distribution. The terminals of primary afferent nociceptive neurons and secondary spinal dorsal horn neurons express α2AAR and α2CAR subtypes, respectively. Spinal delivery of these agents serves to reduce their side effects, which are mediated largely at supraspinal sites, by concentrating the drugs at the spinal level. Targeting these spinal α2ARs with one of five selective therapeutic agonists, clonidine, dexmedetomidine, brimonidine, ST91 and moxonidine, produces significant antinociception that can work in concert with opioid agonists to yield synergistic antinociception. Application of several genetically altered mouse lines had facilitated identification of the primary receptor subtypes that likely mediate the antinociceptive effects of these agents. This review provides first an anatomical description of the localization of the three subtypes in the central nervous system, second a detailed account of the pharmacological history of each of these six primary agonists, and finally a comprehensive report of the specific interactions of other GPCR agonists with each of the six principal α2AR agonists featured. PMID:19393691

  1. 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

  2. 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

  3. Alpha(1)-adrenergic receptor subtypes: non-identical triplets with different dancing partners?

    PubMed

    Hague, Chris; Chen, Zhongjian; Uberti, Michelle; Minneman, Kenneth P

    2003-12-12

    Alpha(1)-adrenergic receptors are one of the three subfamilies of G protein coupled receptors activated by epinephrine and norepinephrine to control important functions in many target organs. Three human subtypes (alpha(1A), alpha(1B), alpha(1D)) are derived from separate genes and are highly homologous in their transmembrane domains but not in their amino or carboxyl termini. Recent advances in our understanding of these "non-identical triplets" include development of knockout mice lacking single or multiple subtypes, new insights into subcellular localization and trafficking, identification of allosteric modulators, and increasing evidence for an important role in brain function. Although all three subtypes activate the same G(q/11) signaling pathway, they also appear to interact with different protein binding partners. Recent evidence suggests they may also form dimers, and may initiate independent signals through pathways yet to be clearly elucidated. Thus, this subfamily represents a common phenomenon of a group of similar but non-identical receptor subtypes activated by the same neurotransmitter, whose individual functional roles remain to be clearly established.

  4. Chronic Caffeine Alters the Density of Adenosine, Adrenergic, Cholinergic, GABA, and Serotonin Receptors and Calcium Channels in Mouse Brain

    PubMed Central

    Shi, Dan; Nikodijević, Olga; Jacobson, Kenneth A.; Daly, John W.

    2012-01-01

    SUMMARY 1. Chronic ingestion of caffeine by male NIH strain mice alters the density of a variety of central receptors. 2. The density of cortical A1 adenosine receptors is increased by 20%, while the density of striatal A2A adenosine receptors is unaltered. 3. The densities of cortical β1 and cerebellar β2 adrenergic receptors are reduced by ca. 25%, while the densities of cortical α1 and α2 adrenergic receptors are not significantly altered. Densities of striatal D1 and D2 dopaminergic receptors are unaltered. The densities of cortical 5 HT1 and 5 HT2 serotonergic receptors are increased by 26–30%. Densities of cortical muscarinic and nicotinic receptors are increased by 40–50%. The density of cortical benzodiazepine-binding sites associated with GABAA receptors is increased by 65%, and the affinity appears slightly decreased. The density of cortical MK-801 sites associated with NMDA-glutaminergic receptors appear unaltered. 4. The density of cortical nitrendipine-binding sites associated with calcium channels is increased by 18%. 5. The results indicate that chronic ingestion of caffeine equivalent to about 100 mg/kg/day in mice causes a wide range of biochemical alterations in the central nervous system. PMID:8242688

  5. 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

  6. alpha- and beta-adrenergic receptor mechanisms in spontaneous contractile activity of rat ileal longitudinal smooth muscle.

    PubMed

    Seiler, Roland; Rickenbacher, Andreas; Shaw, Sidney; Balsiger, Bruno M

    2005-02-01

    Gastrointestinal motility is influenced by adrenergic modulation. Our aim was to identify specific subtypes of adrenergic receptors involved in inhibitory mechanisms that modulate gut smooth muscle contractile activity. Muscle strips of rat ileal longitudinal muscle were evaluated for spontaneous contractile activity and for equimolar dose-responses (10(-7) to 3 x 10(-5) M) to the adrenergic agents norepinephrine (nonselective agonist), phenylephrine (alpha(1)-agonist), clonidine (alpha(2)-agonist), prenalterol (beta(1)-agonist), ritodrine (beta(2)-agonist), and ZD7114 (beta(3)-agonist) in the presence and absence of tetrodotoxin (nonselective nerve blocker). Norepinephrine (3 x 10(-5) M) inhibited 65 +/- 6% (mean +/- SEM) of spontaneous contractile activity. The same molar dose of ritodrine, phenylephrine, or ZD7114 resulted in less inhibition (46 +/- 7%, 31 +/- 5%, and 39 +/- 3%, respectively; P < 0.05). The calculated molar concentration of ZD7114 needed to induce 50% inhibition was similar to that of norepinephrine, whereas higher concentrations of phenylephrine or ritodrine were required. Clonidine and prenalterol had no effect on contractile activity. Blockade of intramural neural transmission by tetrodotoxin affected the responses to ritodrine and phenylephrine (but not to norepinephrine or ZD7114), suggesting that these agents exert part of their effects via neurally mediated enteric pathways. Our results suggest that adrenergic modulation of contractile activity in the rat ileum is mediated primarily by muscular beta(3)-, beta(2)-, and alpha(1)-receptor mechanisms; the latter two also involve neural pathways.

  7. Safety profile of mineralocorticoid receptor antagonists: Spironolactone and eplerenone.

    PubMed

    Lainscak, Mitja; Pelliccia, Francesco; Rosano, Giuseppe; Vitale, Cristiana; Schiariti, Michele; Greco, Cesare; Speziale, Giuseppe; Gaudio, Carlo

    2015-12-01

    Spironolactone was first developed over 50 years ago as a potent mineralocorticoid receptor antagonist with undesirable side effects; it was followed a decade ago by eplerenone, which is less potent but much more mineralocorticoid receptor-specific. From a marginal role as a potassium-sparing diuretic, spironolactone has been shown to be an extraordinarily effective adjunctive agent in the treatment of progressive heart failure. Also, spironolactone is safe and protective in arterial hypertension, particularly in patients with so-called resistant hypertension. Eplerenone is the second oral aldosterone antagonist available for the treatment of arterial hypertension and heart failure. Treatment with eplerenone has been associated with decreased blood pressure and improved survival for patients with heart failure and reduced left ventricular ejection fraction. Due to the selectivity of eplerenone for the aldosterone receptor, severe adverse effects such as gynecomastia and vaginal bleeding seem to be less likely in patients who take eplerenone than in those who take spironolactone. The most common and potentially dangerous side effect of spironolactone--hyperkalemia--is also observed with eplerenone but the findings from clinical trials do not indicate more hyperkalemia induced drug withdrawals. Treatment with eplerenone should be initiated at a dosage of 25mg once daily and titrated to a target dosage of 50mg once daily preferably within 4 weeks. Serum potassium levels and renal function should be assessed prior to initiating eplerenone therapy, and periodic monitoring is recommended, especially in patients at high risk of developing hyperkalemia.

  8. Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity

    SciTech Connect

    Maton, P.N.; Sutliff, V.E.; Jensen, R.T.; Gardner, J.D.

    1985-04-01

    The authors used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ- lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of /sup 125/I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain.

  9. Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists.

    PubMed

    Ajram, Laura; Begg, Malcolm; Slack, Robert; Cryan, Jenni; Hall, David; Hodgson, Simon; Ford, Alison; Barnes, Ashley; Swieboda, Dawid; Mousnier, Aurelie; Solari, Roberto

    2014-04-15

    The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

  10. Substituted Tetrahydroisoquinolines as Selective Antagonists for the Orexin 1 Receptor

    PubMed Central

    Perrey, David A.; German, Nadezhda A.; Gilmour, Brian P.; Li, Jun-Xu; Harris, Danni L.; Thomas, Brian F.; Zhang, Yanan

    2013-01-01

    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 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

  11. 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

  12. Structure of the gene for human. beta. /sub 2/-adrenergic receptor: expression and promoter characterization

    SciTech Connect

    Emorine, L.J.; Marullo, S.; Delavier-Klutchko, C.; Kaveri, S.V.; Durieu-Trautmann, O.; Strosberg, A.D.

    1987-10-01

    The genomic gene coding for the human ..beta../sub 2/-adrenergic receptor (..beta../sub 2/AR) from A431 epidermoid cells has been isolated. Transfection of the gene into eukaryotic cells restores a fully active receptor/GTP-binding protein/adenylate cyclase complex with ..beta../sub 2/AR properties. Southern blot analyses with ..beta../sub 2/AR-specific probes show that a single ..beta../sub 2/AR gene is common to various human tissues and that its flanking sequences are highly conserved among humans and between man and rabbit, mouse, and hamster. Functional significance of these regions is supported by the presence of a promoter region (including mRNA cap sites, two TATA boxes, a CAAT box, and three G + C-rich regions that resemble binding sites for transcription factor Sp1) 200-300 base pairs 5' to the translation initiation codon. In the 3' flanking region, sequences homologous to glucocorticoid-response elements might be responsible for the increased expression of the ..beta../sub 2/AR gene observed after treatment of the transfected cells with hydrocortisone. In addition, 5' to the promoter region, an open reading frame encodes a 251-residue polypeptide that displays striking homologies with protein kinases and other nucleotide-binding proteins.

  13. β-Adrenergic receptor blockade blunts postexercise skeletal muscle mitochondrial protein synthesis rates in humans

    PubMed Central

    Robinson, Matthew M.; Bell, Christopher; Peelor, Frederick F.

    2011-01-01

    β-Adrenergic receptor (AR) signaling is a regulator of skeletal muscle protein synthesis and mitochondrial biogenesis in mice. We hypothesized that β-AR blockade blunts postexercise skeletal muscle mitochondrial protein synthesis rates in adult humans. Six healthy men (mean ± SD: 26 ± 6 yr old, 39.9 ± 4.9 ml·kg−1·min−1 peak O2 uptake, 26.7 ± 2.0 kg/m2 body mass index) performed 1 h of stationary cycle ergometer exercise (60% peak O2 uptake) during 1) β-AR blockade (intravenous propranolol) and 2) administration of saline (control). Skeletal muscle mitochondrial, myofibrillar, and sarcoplasmic protein synthesis rates were assessed using [2H5]phenylalanine incorporation into skeletal muscle proteins after exercise. The mRNA content of signals for mitochondrial biogenesis was determined using real-time PCR. β-AR blockade decreased mitochondrial (from 0.217 ± 0.076 to 0.135 ± 0.031%/h, P < 0.05), but not myofibrillar or sarcoplasmic, protein synthesis rates. Peroxisome proliferator-activated receptor-γ coactivator-1α mRNA was increased ∼2.5-fold (P < 0.05) at 5 h compared with 1 h postexercise but was not influenced by β-AR blockade. We conclude that decreased β-AR signaling during cycling can blunt the postexercise increase in mitochondrial protein synthesis rates without affecting mRNA content. PMID:21613574

  14. 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.

  15. Beta-adrenergic receptors are differentially expressed in distinct interneuron subtypes in the rat hippocampus.

    PubMed

    Cox, David J; Racca, Claudia; LeBeau, Fiona E N

    2008-08-20

    Noradrenaline (NA) acting via beta-adrenergic receptors (betaARs) plays an important role in the modulation of memory in the hippocampus. betaARs have been shown to be expressed in principal cells, but their distribution across different interneuron classes is unknown. We have used specific interneuron markers including calcium binding proteins (parvalbumin, calbindin, and calretinin) and neuropeptides (somatostatin, neuropeptide Y, and cholecystokinin) together with either beta1AR or beta2AR to determine the distribution of these receptors in all major subfields of the hippocampus. We found that beta1AR-expressing interneurons were more prevalent in the CA3 and CA1 regions of the hippocampus than in the dentate gyrus, where they were relatively sparse. beta2AR-expressing interneurons were more uniformly distributed between all three regions of the hippocampus. A high proportion of neuropeptide Y-containing interneurons in the dentate gyrus co-expressed beta2AR. beta1AR labeling was common in interneurons expressing somatostatin and parvalbumin in the CA3 and CA1 regions, particularly in the stratum oriens of these regions. beta2AR labeling was more likely to be found than beta1AR labeling in cholecystokinin-expressing interneurons. In contrast, calretinin-containing interneurons were virtually devoid of beta1AR or beta2AR labeling. These regional and interneuron type-specific differences suggest functionally distinct roles for NA in modulating hippocampal activity via activation of betaARs.

  16. Adrenergic modulation of NMDA receptors in prefrontal cortex is differentially regulated by RGS proteins and spinophilin

    PubMed Central

    Liu, Wenhua; Yuen, Eunice Y.; Allen, Patrick B.; Feng, Jian; Greengard, Paul; Yan, Zhen

    2006-01-01

    The noradrenergic system in the prefrontal cortex (PFC) is involved in many physiological and psychological processes, including working memory and mood control. To understand the functions of the noradrenergic system, we examined the regulation of NMDA receptors (NMDARs), key players in cognition and emotion, by α1- and α2-adrenergic receptors (α1-ARs, α2-ARs) in PFC pyramidal neurons. Applying norepinephrine or a norepinephrine transporter inhibitor reduced the amplitude but not paired-pulse ratio of NMDAR-mediated excitatory postsynaptic currents (EPSC) in PFC slices. Specific α1-AR or α2-AR agonists also decreased NMDAR-EPSC amplitude and whole-cell NMDAR current amplitude in dissociated PFC neurons. The α1-AR effect depended on the phospholipase C–inositol 1,4,5-trisphosphate–Ca2+ pathway, whereas the α2-AR effect depended on protein kinase A and the microtubule-based transport of NMDARs that is regulated by ERK signaling. Furthermore, two members of the RGS family, RGS2 and RGS4, were found to down-regulate the effect of α1-AR on NMDAR currents, whereas only RGS4 was involved in inhibiting α2-AR regulation of NMDAR currents. The regulating effects of RGS2/4 on α1-AR signaling were lost in mutant mice lacking spinophilin, which binds several RGS members and G protein-coupled receptors, whereas the effect of RGS4 on α2-AR signaling was not altered in spinophilin-knockout mice. Our work suggests that activation of α1-ARs or α2-ARs suppresses NMDAR currents in PFC neurons by distinct mechanisms. The effect of α1-ARs is modified by RGS2/4 that are recruited to the receptor complex by spinophilin, whereas the effect of α2-ARs is modified by RGS4 independent of spinophilin. PMID:17101972

  17. Cangrelor: a novel P2Y12 receptor antagonist.

    PubMed

    Norgard, Nicholas B

    2009-08-01

    Antiplatelet therapy is critical in the prevention of thrombotic complications of acute coronary syndrome and percutaneous coronary interventions. Current antiplatelet agents (aspirin, clopidogrel and glycoprotein IIb/IIIa antagonists) have demonstrated the capacity to reduce major adverse cardiac events. However, these agents have limitations that compromise their clinical utility. The platelet P2Y12 receptor plays a central role in platelet function and is a focus in the development of antiplatelet therapies. Cangrelor is a potent, competitive inhibitor of the P2Y12 receptor that is administered by intravenous infusion and rapidly achieves near complete inhibition of ADP-induced platelet aggregation. This investigational drug has been studied for use during coronary procedures and the management of patients experiencing acute coronary syndrome and is undergoing evaluation for use in the prevention of perioperative stent thrombosis.

  18. Is All Radiation-Induced Emesis Ameliorated by 5-HT3 Receptor Antagonists

    DTIC Science & Technology

    1992-01-01

    5 - HT3 receptor antagonists ;~// 9-72 Bernard M.I Rabin 0’) and Gregory L. Kingt2) -) Behavioral Sciences and 2 PhYSzo~o~y Dcpiarlrnvni . Arm,. ii - R...RY Exposing ferrets to gamuma rays or X-rays produces vomiting that can be attenuated by 5 - HT3 receptor antagonists and by subdiaphraqmatic vagotomy...Pretreating ferrets with serotonin type-3 ( 5 - HT3 ) receptor antagonists or performing bilateral subdiaphragmatic vagotomy reliably attenuates the

  19. Interaction of Pyridostigmine with the 5-HT(3) Receptor Antagonist Ondansetron in Guinea Pigs

    DTIC Science & Technology

    1993-05-13

    5 - HT3 RECEPTOR - ANTAGONIST .ONDANSETRON IN GUINEA PIGS BR. Capacio, CE. Byers...apart. REFERENCES 1. Fozard JR. 5 -HT; The Enigma Variations. =JE, 8, 501-506 (December 1987). 2. Watling KJ. 5 - HT3 Receptor Agonists and Antagonists . In... 5 -HT receptor subtype three antagonists (5HT 3 ) such as the compound ondansetron (OND) have been identified as useful in the treatment of

  20. Dynamics of the β2-adrenergic G-protein coupled receptor revealed by hydrogen-deuterium exchange

    PubMed Central

    Zhang, Xi; Chien, Ellen Y.T.; Chalmers, Michael J.; Pascal, Bruce D.; Gatchalian, Jovylyn; Stevens, Raymond C.; Griffin, Patrick R.

    2010-01-01

    To examine the molecular details of ligand activation of G-protein coupled receptor (GPCRs), emphasis has been placed on structure determination of these receptors with stabilizing ligands. Here we present the methodology for receptor dynamics characterization of the GPCR human β2 adrenergic receptor bound to the inverse agonist carazolol using the technique of amide hydrogen/deuterium exchange coupled with mass spectrometry (HDX MS). The HDX MS profile of receptor bound to carazolol is consistent with thermal parameter observations in the crystal structure and provides additional information in highly dynamic regions of the receptor and chemical modifications demonstrating the highly complementary nature of the techniques. Following optimization of HDX experimental conditions for this membrane protein, better than 89% sequence coverage was obtained for the receptor. The methodology presented paves the way for future analysis of β2AR bound to pharmacologically distinct ligands as well as analysis of other GPCR family members. PMID:20058880

  1. Involvement of serotoninergic 5-HT1A/2A, alpha-adrenergic and dopaminergic D1 receptors in St. John's wort-induced prepulse inhibition deficit: a possible role of hyperforin.

    PubMed

    Tadros, Mariane G; Mohamed, Mohamed R; Youssef, Amal M; Sabry, Gilane M; Sabry, Nagwa A; Khalifa, Amani E

    2009-05-16

    Prepulse inhibition (PPI) of acoustic startle response is a valuable paradigm for sensorimotor gating processes. Previous research showed that acute administration of St. John's wort extract (500 mg/kg, p.o.) to rats caused significant disruption of PPI while elevating monoamines levels in some brain areas. The cause-effect relationship between extract-induced PPI disruption and augmented monoaminergic transmission was studied using different serotoninergic, adrenergic and dopaminergic antagonists. The effects of hypericin and hyperforin, as the main active constituents of the extract, on PPI response were also tested. PPI disruption was prevented after blocking the serotoninergic 5-HT1A and 5-HT2A, alpha-adrenergic and dopaminergic D1 receptors. Results also demonstrated a significant PPI deficit after acute treatment of rats with hyperforin, and not hypericin. In some conditions manifesting disrupted PPI response, apoptosis coexists. Electrophoresis of DNA isolated from brains of hyperforin-treated animals revealed absence of any abnormal DNA fragmentation patterns. It is concluded that serotoninergic 5-HT1A and 5-HT2A, alpha-adrenergic and dopaminergic D1 receptors are involved in the disruptive effect of St. John's wort extract on PPI response in rats. We can also conclude that hyperforin, and not hypericin, is one of the active ingredients responsible for St. John's wort-induced PPI disruption with no relation to apoptotic processes.

  2. 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.

  3. Classification and virtual screening of androgen receptor antagonists.

    PubMed

    Li, Jiazhong; Gramatica, Paola

    2010-05-24

    Computational tools, such as quantitative structure-activity relationship (QSAR), are highly useful as screening support for prioritization of substances of very high concern (SVHC). From the practical point of view, QSAR models should be effective to pick out more active rather than inactive compounds, expressed as sensitivity in classification works. This research investigates the classification of a big data set of endocrine-disrupting chemicals (EDCs)-androgen receptor (AR) antagonists, mainly aiming to improve the external sensitivity and to screen for potential AR binders. The kNN, lazy IB1, and ADTree methods and the consensus approach were used to build different models, which improve the sensitivity on external chemicals from 57.1% (literature) to 76.4%. Additionally, the models' predictive abilities were further validated on a blind collected data set (sensitivity: 85.7%). Then the proposed classifiers were used: (i) to distinguish a set of AR binders into antagonists and agonists; (ii) to screen a combined estrogen receptor binder database to find out possible chemicals that can bind to both AR and ER; and (iii) to virtually screen our in-house environmental chemical database. The in silico screening results suggest: (i) that some compounds can affect the normal endocrine system through a complex mechanism binding both to ER and AR; (ii) new EDCs, which are nonER binders, but can in silico bind to AR, are recognized; and (iii) about 20% of compounds in a big data set of environmental chemicals are predicted as new AR antagonists. The priority should be given to them to experimentally test the binding activities with AR.

  4. Functional receptor coupling to Gi is a mechanism of agonist-promoted desensitization of the beta2-adrenergic receptor.

    PubMed

    Tepe, N M; Liggett, S B

    2000-01-01

    The beta2-adrenergic receptor (beta2AR) couples to Gs activating adenylyl cyclase (AC) and increasing cAMP. Such signaling undergoes desensitization with continued agonist exposure. Beta2AR also couple to Gi after receptor phosphorylation by the cAMP dependent protein kinase A, but the efficiency of such coupling is not known. Given the PKA dependence of beta2AR-Gi coupling, we explored whether this may be a mechanism of agonist-promoted desensitization. HEK293 cells were transfected to express beta2AR or beta2AR and Gialpha2, and then treated with vehicle or the agonist isoproterenol to evoke agonist-promoted beta2AR desensitization. Membrane AC activities showed that Gialpha2 overexpression decreased basal levels, but the fold-stimulation of the AC over basal by agonist was not altered. However, with treatment of the cells with isoproterenol prior to membrane preparation, a marked decrease in agonist-stimulated AC was observed with the cells overexpressing Gialpha2. In the absence of such overexpression, beta2AR desensitization was 23+/-7%, while with 5-fold Gialpha2 overexpression desensitization was 58+/-5% (p<0.01, n=4). The effect of Gi on desensitization was receptor-specific, in that forskolin responses were not altered by G(i)alpha2 overexpression. Thus, acquired beta2AR coupling to Gi is an important mechanism of agonist-promoted desensitization, and pathologic conditions that increase Gi levels contribute to beta2AR dysfunction.

  5. Monitoring the human beta1, beta2, beta3 adrenergic receptors expression and purification in Pichia pastoris using the fluorescence properties of the enhanced green fluorescent protein.

    PubMed

    Talmont, Franck

    2009-01-01

    The three beta adrenergic receptor subtypes, beta1-, beta2- and beta3-, were expressed in the methylotrophic yeast Pichia pastoris. These receptors were N-terminally fused to the enhanced green fluorescent protein (EGFP) and the fluorescent properties of EGFP were used: (1) to select the recombinant strains, (2) to monitor the expression of the fluorescent receptors, and (3) to monitor the purification of the receptors by immobilized metal affinity chromatography. We demonstrate here that Pichia pastoris can be an alternative host to express and purify milligram amounts of human beta adrenergic receptors.

  6. Adrenergic beta-1 receptor genetic variation predicts longitudinal rate of GFR decline in hypertensive nephrosclerosis

    PubMed Central

    Fung, Maple M.; Chen, Yuqing; Lipkowitz, Michael S.; Salem, Rany M.; Bhatnagar, Vibha; Mahata, Manjula; Nievergelt, Caroline M.; Rao, Fangwen; Mahata, Sushil K.; Schork, Nicholas J.; Brophy, Victoria H.; O’Connor, Daniel T.

    2009-01-01

    Background. End-stage renal disease (ESRD) due to hypertension is common and displays familial aggregation in African Americans, suggesting genetic risk factors, including adrenergic activity alterations which are noted in both hypertension and ESRD. Methods. We analysed 554 hypertensive nephrosclerosis participants (without clinically significant proteinuria) from the longitudinal National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) African American Study of Kidney Disease and Hypertension (AASK) cohort to determine whether decline in glomerular filtration rate (GFR) over ∼3.8 years was predicted by common genetic variation within the adrenergic beta-1 (ADRB1) receptor at non-synonymous positions Ser49Gly and Arg389Gly. Results. The polymorphism at Ser49Gly (though not Arg389Gly, in only partial linkage disequilibrium at r2 = 0.18) predicted the chronic rate of GFR decline, with minimal decline in Gly49/Gly49 (minor allele) homozygotes compared to Ser49 carriers; concordant results were observed for haplotypes and diploid haplotype pairs at the locus. An independent replication study in 1244 subjects from the San Diego Veterans Affairs Hypertension Cohort confirmed that Gly49/Gly49 homozygotes displayed the least rapid decline of eGFR over ∼3.6 years. Conclusion. We conclude that GFR decline rate in hypertensive renal disease is controlled in part by genetic variation within the adrenergic pathway, particularly at ADRB1. The results suggest novel strategies to approach the role of the adrenergic system in the risk and treatment of progressive renal disease. PMID:19745105

  7. 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.

  8. 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.

  9. Site-specific O-Glycosylation by Polypeptide N-Acetylgalactosaminyltransferase 2 (GalNAc-transferase T2) Co-regulates β1-Adrenergic Receptor N-terminal Cleavage.

    PubMed

    Goth, Christoffer K; Tuhkanen, Hanna E; Khan, Hamayun; Lackman, Jarkko J; Wang, Shengjun; Narimatsu, Yoshiki; Hansen, Lasse H; Overall, Christopher M; Clausen, Henrik; Schjoldager, Katrine T; Petäjä-Repo, Ulla E

    2017-03-17

    The β1-adrenergic receptor (β1AR) is a G protein-coupled receptor (GPCR) and the predominant adrenergic receptor subtype in the heart, where it mediates cardiac contractility and the force of contraction. Although it is the most important target for β-adrenergic antagonists, such as β-blockers, relatively little is yet known about its regulation. We have shown previously that β1AR undergoes constitutive and regulated N-terminal cleavage participating in receptor down-regulation and, moreover, that the receptor is modified by O-glycosylation. Here we demonstrate that the polypeptide GalNAc-transferase 2 (GalNAc-T2) specifically O-glycosylates β1AR at five residues in the extracellular N terminus, including the Ser-49 residue at the location of the common S49G single-nucleotide polymorphism. Using in vitro O-glycosylation and proteolytic cleavage assays, a cell line deficient in O-glycosylation, GalNAc-T-edited cell line model systems, and a GalNAc-T2 knock-out rat model, we show that GalNAc-T2 co-regulates the metalloproteinase-mediated limited proteolysis of β1AR. Furthermore, we demonstrate that impaired O-glycosylation and enhanced proteolysis lead to attenuated receptor signaling, because the maximal response elicited by the βAR agonist isoproterenol and its potency in a cAMP accumulation assay were decreased in HEK293 cells lacking GalNAc-T2. Our findings reveal, for the first time, a GPCR as a target for co-regulatory functions of site-specific O-glycosylation mediated by a unique GalNAc-T isoform. The results provide a new level of β1AR regulation that may open up possibilities for new therapeutic strategies for cardiovascular diseases.

  10. Cell surface adrenergic receptor stimulation modifies the endothelial response to SIRS. Systemic Inflammatory Response Syndrome.

    PubMed

    Tighe, D; Moss, R; Bennett, D

    1996-11-01

    The complex pathway seen in patients with the systemic inflammatory response syndrome (SIRS) does not readily respond to mediator blockade. All such trials conducted in SIRS patients have shown no benefit in reducing mortality. We have shown experimentally that in sepsis, the administration of beta 2-adrenoceptor agonists reduces hepatic cellular injury, whereas administration of an alpha 1-adrenoceptor agonist increases hepatic cellular injury. Inflammatory mediators can cause a dose-related reversible change in target endothelial cells (ECs). There is a substantial body of literature describing the anti-inflammatory effects of beta 2-adrenoceptor agonists. They reduce both the increased permeability and the production of inflammatory mediators from ECs. Cellular transduction processes are involved when adrenergic receptor agonists modify either the anti-inflammatory or proinflammatory response to sepsis in ECs. Inflammatory mediators and alpha 1-adrenoceptor agonists stimulate their trimeric G protein-linked receptors to produce diacylglycerol (DAG) and increase the intracellular concentration of calcium. DAG is involved in the production of both inflammatory proteins and lipids. In addition, mitogen-activated protein kinase (MAPK) is activated which is also involved in the production of inflammatory proteins and lipids. beta 2-adrenoceptor agonists activate their trimeric G protein-linked receptors to produce the stimulatory G protein (Gs). Gs stimulates adenyl cyclase to form cyclic adenosine monophosphate (cAMP) and activate protein kinase A (PKA). PKA is involved in activating gene transcription agents to produce anti-inflammatory proteins such as interleukin-10. PKA also inhibits phospholipase C and MAPK. Although promising, the use of beta-adrenoceptor agonists or agonists that increase cellular cAMP to activate the cells' endogenous anti-inflammatory pathway requires further study.

  11. Pharmacogenetics of beta1-adrenergic receptors in heart failure and hypertension.

    PubMed

    Mialet-Perez, J; Liggett, S B

    2006-06-01

    Currently it is generally accepted that an individual's genetic makeup can modify the efficacy of drug treatment or the risk of adverse reactions. Although not a new concept, the availability of human genome sequence and rapid genotyping at variable loci in drug targets or metabolizing genes has provided new opportunities for the field termed "pharmacogenetics". Somewhat surprisingly, multiple studies have shown the existence of common variants (polymorphisms) in members of the G-protein coupled receptor superfamily, which constitute around 50% of all the targets of currently prescribed drugs. The beta1-adrenergic receptors (beta1ARs) are interesting candidates for pharmacogenetic studies in two complex cardiovascular disease, heart failure and hypertension, since they mediate the effects of catecholamines in the sympathetic nervous system. These receptors are involved in the progression and treatment (beta-blockers therapy) of both diseases, and have polymorphisms that show altered function or regulation as compared to their allelic counterparts in recombinant expression systems and genetically modified mice. These results have prompted prospective and retrospective clinical studies examining whether polymorphisms of these genes are risk factors, disease modifiers, or predictors of b-blocker response in heart failure and hypertension. To date, it appears that beta1AR variants are very likely one genetic component that defines responsiveness to beta-blockers in heart failure and hypertension. Altogether, results are promising, but discrepancies between studies require resolution before these polymorphisms can be utilized in practice. With the goal of personalizing therapy based on an individual's genetic makeup, additional adequately powered, multiethnic, multi-drug studies will be needed.

  12. The adrenergic regulation of the cardiovascular system in the South American rattlesnake, Crotalus durissus.

    PubMed

    Galli, Gina L J; Skovgaard, Nini; Abe, Augusto S; Taylor, Edwin W; Wang, Tobias

    2007-11-01

    The present study investigates adrenergic regulation of the systemic and pulmonary circulations of the anaesthetised South American rattlesnake, Crotalus durissus. Haemodynamic measurements were made following bolus injections of adrenaline and adrenergic antagonists administered through a systemic arterial catheter. Adrenaline caused a marked systemic vasoconstriction that was abolished by phentolamine, indicating this response was mediated through alpha-adrenergic receptors. Injection of phentolamine gave rise to a pronounced vasodilatation (systemic conductance (G(sys)) more than doubled), while injection of propranolol caused a systemic vasoconstriction, pointing to a potent alpha-adrenergic, and a weaker beta-adrenergic tone in the systemic vasculature of Crotalus. Overall, the pulmonary vasculature was far less responsive to adrenergic stimulation than the systemic circulation. Adrenaline caused a small but non-significant pulmonary vasodilatation and there was tendency of reducing this dilatation after either phentolamine or propranolol. Injection of phentolamine increased pulmonary conductance (G(pul)), while injection of propranolol produced a small pulmonary constriction, indicating that alpha-adrenergic and beta-adrenergic receptors contribute to a basal regulation of the pulmonary vasculature. Our results suggest adrenergic regulation of the systemic vasculature, rather than the pulmonary, may be an important factor in the development of intracardiac shunts.

  13. Guanidinoethyl sulphonate is a glycine receptor antagonist in striatum.

    PubMed

    Sergeeva, Olga A; Chepkova, Aisa N; Haas, Helmut L

    2002-11-01

    1. Guanidinoethyl sulphonate (GES) is an analogue of taurine and an inhibitor of taurine transport. Interactions of GES with GABA(A) and glycine receptors are studied by whole cell recording and fast drug application in isolated striatal neurons of the mouse. 2. We confirm that GES is a weak agonist at GABA(A) receptors, and is able to antagonize GABA-evoked responses. GES did not gate GlyR. 3. GES antagonized glycine responses in a concentration-dependent and surmountable manner. Glycine dose-response curves were shifted to the right by GES (0.5 mM), yielding EC(50)s and Hill coefficients of 62 micro M and 2.5 in control, 154 micro M and 1.3 in the presence of GES. 4. GlyR-mediated taurine responses were competitively antagonized by GES. Taurine dose-response curves, in contrast to the glycine dose-response curves were shifted by GES to the right in a parallel manner. 5. The GlyR-block by GES was not voltage-dependent. 6. In contrast to our findings in the mouse, in rat striatal neurons which lack expression of the alpha3 GlyR subunit, GES shifted the glycine dose-response curve to the right in a parallel way without affecting the maximal response. Subtype-specificity of the GES action at GlyR must await further investigation in artificial expression systems. 7. We conclude that GES is a competitive antagonist at GlyR. The antagonistic action of GES at inhibitory ionotropic receptors can explain its epileptogenic action. Care must be taken with the interpretation of data on GES evoked taurine release.

  14. Role of β-Adrenergic Receptor Regulation of TNF-α and Insulin Signaling in Retinal Müller Cells

    PubMed Central

    Walker, Robert J.; Anderson, Nancy M.; Jiang, Youde; Bahouth, Suleiman

    2011-01-01

    Purpose. The goal of this study was to determine the relationship of TNF-α and the downregulation of insulin receptor signaling in retinal Müller cells cultured under hyperglycemic conditions and the role of β-adrenergic receptors in regulating these responses. Methods. Retinal Müller cells were cultured in normal (5 mM) or high (25 mM) glucose until 80% confluent and then were reduced to 2% serum for 18 to 24 hours. The cells were then treated with 10 μM salmeterol followed by Western blot analysis or ELISA. For TNF-α inhibitory studies, the cells were treated with 5 ng/mL of TNF-α for 30 minutes or by a 30-minute pretreatment with TNF-α followed by salmeterol for 6 hours. In the TNF-α short hairpin (sh)RNA experiments, the cells were cultured until 90% confluent, followed by transfection with TNF-α shRNA for 18 hours. Results. TNF-α-only treatments of Müller cells resulted in significant decreases of tyrosine phosphorylation of the insulin receptor and Akt in high-glucose conditions. Salmeterol (10 μM), a β-2-adrenergic receptor agonist, significantly increased phosphorylation of both insulin receptor and Akt. TNF-α shRNA significantly decreased phosphorylation of IRS-1Ser307, which was further decreased after salmeterol+TNF-α shRNA. Both TNF-α shRNA and salmeterol significantly reduced death of the retinal Müller cells. Conclusions. These studies demonstrate that β-adrenergic receptor agonists in vitro can restore the loss of insulin receptor activity noted in diabetes. By decreasing the levels of TNF-α and decreasing the phosphorylation of IRS-1Ser307 while increasing tyrosine phosphorylation of insulin receptor, these results suggest a possible mechanism by which restoration of β-adrenergic receptor signaling may protect the retina against diabetes-induced damage. PMID:22110065

  15. Melatonin receptor-mediated protection against myocardial ischaemia/reperfusion injury: role of its anti-adrenergic actions.

    PubMed

    Genade, Sonia; Genis, Amanda; Ytrehus, Kirsti; Huisamen, Barbara; Lochner, Amanda

    2008-11-01

    Melatonin has potent cardioprotective properties. These actions have been attributed to its free radical scavenging and anti-oxidant actions, but may also be receptor mediated. Melatonin also exerts powerful anti-adrenergic actions based on its effects on contractility of isolated papillary muscles. The aims of this study were to determine whether melatonin also has anti-adrenergic effects on the isolated perfused rat heart, to determine the mechanism thereof and to establish whether these actions contribute to protection of the heart during ischaemia/reperfusion. The results showed that melatonin (50 microM) caused a significant reduction in both isoproterenol (10(-7) M) and forskolin (10(-6) M) induced cAMP production and that both these responses were melatonin receptor dependent, since the blocker, luzindole (5 x 10(-6) M) abolished this effect. Nitric oxide (NO), as well as guanylyl cyclase are involved, as L-NAME (50 microM), an NO synthase inhibitor and ODQ (20 microM), a guanylyl cyclase inhibitor, significantly counteracted the effects of melatonin. Protein kinase C (PKC), as indicated by the use of the inhibitor bisindolylmaleimide (50 microM), also play a role in melatonin's anti-adrenergic actions. These actions of melatonin are involved in its cardioprotection: simultaneous administration of L-NAME or ODQ with melatonin, before and after 35 min regional ischaemia, completely abolished its cardioprotection. PKC, on the other hand, had no effect on the melatonin-induced reduction in infarct size. Cardioprotection by melatonin was associated with a significant activation of PKB/Akt and attenuated activation of the pro-apoptotic kinase, p38MAPK during early reperfusion. In summary, the results show that melatonin-induced cardioprotection may be receptor dependent, and that its anti-adrenergic actions, mediated by NOS and guanylyl cyclase activation, are important contributors.

  16. β1-Adrenergic receptor deficiency in ghrelin-expressing cells causes hypoglycemia in susceptible individuals

    PubMed Central

    Mani, Bharath K.; Osborne-Lawrence, Sherri; Vijayaraghavan, Prasanna; Hepler, Chelsea; Zigman, Jeffrey M.

    2016-01-01

    Ghrelin is an orexigenic gastric peptide hormone secreted when caloric intake is limited. Ghrelin also regulates blood glucose, as emphasized by the hypoglycemia that is induced by caloric restriction in mouse models of deficient ghrelin signaling. Here, we hypothesized that activation of β1-adrenergic receptors (β1ARs) localized to ghrelin cells is required for caloric restriction–associated ghrelin release and the ensuing protective glucoregulatory response. In mice lacking the β1AR specifically in ghrelin-expressing cells, ghrelin secretion was markedly blunted, resulting in profound hypoglycemia and prevalent mortality upon severe caloric restriction. Replacement of ghrelin blocked the effects of caloric restriction in β1AR-deficient mice. We also determined that treating calorically restricted juvenile WT mice with beta blockers led to reduced plasma ghrelin and hypoglycemia, the latter of which is similar to the life-threatening, fasting-induced hypoglycemia observed in infants treated with beta blockers. These findings highlight the critical functions of ghrelin in preventing hypoglycemia and promoting survival during severe caloric restriction and the requirement for ghrelin cell–expressed β1ARs in these processes. Moreover, these results indicate a potential role for ghrelin in mediating beta blocker–associated hypoglycemia in susceptible individuals, such as young children. PMID:27548523

  17. Genetic variation in the α1A-adrenergic receptor and phenylephrine-mediated venoconstriction.

    PubMed

    Adefurin, A; Ghimire, L V; Kohli, U; Muszkat, M; Sofowora, G G; Li, C; Paranjape, S Y; Stein, C M; Kurnik, D

    2015-08-01

    There is large interindividual variability and ethnic differences in phenylephrine-mediated vasoconstriction. We tested the hypothesis that genetic variation in ADRA1A, the α1A adrenergic receptor gene, contributes to the variability and ethnic differences. We measured local dorsal hand vein responses to increasing doses of phenylephrine in 64 Caucasians and 42 African-Americans and genotyped for 32 ADRA1A single nucleotide polymorphisms. The ED50 ranged from 11 to 5442 ng min(-1), and the Emax ranged from 13.5-100%. The rs574647 variant was associated with a trend towards lower logED50 in each race and in the combined cohort (P=0.008). In addition, rs1079078 was associated with a trend to higher logED50 in each race and in the combined cohort (P=0.011). Neither variant accounted for the ethnic differences in response. None of the ADRA1A haplotypes was associated with the outcomes. In conclusion, ADRA1A variants do not contribute substantially to the marked interindividual variability or ethnic differences in phenylephrine-mediated venoconstriction.

  18. Gender-related differences in β-adrenergic receptor-mediated cardiac remodeling.

    PubMed

    Zhu, Baoling; Liu, Kai; Yang, Chengzhi; Qiao, Yuhui; Li, Zijian

    2016-12-01

    Cardiac remodeling is the pathological basis of various cardiovascular diseases. In this study, we found gender-related differences in β-adrenergic receptor (AR)-mediated pathological cardiac remodeling. Cardiac remodeling model was established by subcutaneous injection of isoprenaline (ISO) for 14 days. Heart rate (HR), mean arterial pressure (MAP), and echocardiography were obtained on 7th and 14th days during ISO administration. Myocardial cross-sectional area and the ratio of heart mass to tibia length (HM/TL) were detected to assess cardiac hypertrophy. Picro-Sirius red staining (picric acid + Sirius red F3B) was used to evaluate cardiac fibrosis. Myocardial capillary density was assessed by immunohistochemistry for von Willebrand factor. Further, real-time PCR was used to measure the expression of β1-AR and β2-AR. Results showed that ISO induced cardiac remodeling, the extent of which was different between female and male mice. The extent of increase in cardiac wall thickness, myocardial cross-sectional area, and collagen deposition in females was less than that in males. However, no gender-related difference was observed in HR, MAP, cardiac function, and myocardial capillary density. The distinctive decrease of β2-AR expression, rather than a decrease of β1-AR expression, seemed to result in gender-related differences in cardiac remodeling.

  19. β-Adrenergic receptor antagonism in mice: a model for pediatric heart disease.

    PubMed

    Sucharov, Carmen C; Hijmans, Jamie G; Sobus, Rebecca D; Melhado, William F A; Miyamoto, Shelley D; Stauffer, Brian L

    2013-10-01

    Children with heart failure are treated with similar medical therapy as adults with heart failure. In contrast to adults with heart failure, these treatment regiments are not associated with improved outcomes in children. Recent studies have demonstrated age-related pathophysiological differences in the molecular mechanisms of heart failure between children and adults. There are no animal models of pediatric cardiomyopathy to allow mechanistic studies. The purpose of the current experiments was to develop a mouse model of pediatric heart disease and test whether the influence of β-adrenergic receptor (β-AR) antagonism could be modeled in this system. We hypothesized that isoproterenol treatment of young mice would provide a model system of cardiac pathology, and that nonselective β-AR blockade would provide benefit in adult, but not young, mice, similar to clinical trial data. We found that isoproterenol treatment (through osmotic minipump implantation) of young and adult mice produced similar degrees of cardiac hypertrophy and recapitulated several age-related molecular abnormalities in human heart failure, including phospholamban phosphorylation and β-AR expression. We also found that nonselective β-AR blockade effectively prevented pathological cardiac growth and collagen expression in the adult but not young mice, and that selective β1-AR blockade was effective in both young and adult isoproterenol-treated mice. In conclusion, we have developed the first model system for β-AR-mediated pediatric heart disease. Furthermore, we have generated novel data suggesting beneficial effects of selective β1-AR blockade in the pediatric heart.

  20. CL316,243, a β3-adrenergic receptor agonist, induces muscle hypertrophy and increased strength

    PubMed Central

    Puzzo, Daniela; Raiteri, Roberto; Castaldo, Clotilde; Capasso, Raffaele; Pagano, Ester; Tedesco, Mariateresa; Gulisano, Walter; Drozd, Lisaveta; Lippiello, Pellegrino; Palmeri, Agostino; Scotto, Pietro; Miniaci, Maria Concetta

    2016-01-01

    Studies in vitro have demonstrated that β3-adrenergic receptors (β3-ARs) regulate protein metabolism in skeletal muscle by promoting protein synthesis and inhibiting protein degradation. In this study, we evaluated whether activation of β3-ARs by the selective agonist CL316,243 modifies the functional and structural properties of skeletal muscles of healthy mice. Daily injections of CL316,243 for 15 days resulted in a significant improvement in muscle force production, assessed by grip strength and weight tests, and an increased myofiber cross-sectional area, indicative of muscle hypertrophy. In addition, atomic force microscopy revealed a significant effect of CL316,243 on the transversal stiffness of isolated muscle fibers. Interestingly, the expression level of mammalian target of rapamycin (mTOR) downstream targets and neuronal nitric oxide synthase (NOS) was also found to be enhanced in tibialis anterior and soleus muscles of CL316,243 treated mice, in accordance with previous data linking β3-ARs to mTOR and NOS signaling pathways. In conclusion, our data suggest that CL316,243 systemic administration might be a novel therapeutic strategy worthy of further investigations in conditions of muscle wasting and weakness associated with aging and muscular diseases. PMID:27874066

  1. 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.

  2. Exposure to cigarette smoke downregulates β2-adrenergic receptor expression and upregulates inflammation in alveolar macrophages.

    PubMed

    Wang, Wei; Li, Xiaoguang; Xu, Jie

    2015-01-01

    Cigarette smoke-triggered inflammation is important in the pathophysiology of chronic obstructive pulmonary disease (COPD). β2-Adrenergic receptor (β2-AR) is abundantly expressed on inflammatory cells, which is associated with inflammation regulation. To observe alterations in inflammation, pathological changes in lung tissues, and detect changes in β2-AR expression, rats were exposed for 4 months to cigarette smoke. Pathological changes were observed in lung tissue sections. The levels of inflammatory mediators tumor necrosis factor (TNF)-α, interleukin (IL)-1β in bronchoalveolar lavage fluid (BALF), and lung tissues were measured using enzyme-linked immunosorbent assay (ELISA). Nuclear factor (NF)-κB activity was detected by electrophoretic mobility shift assay (EMSA). Exposure to this regimen of cigarette smoke induced peribronchial and perivascular lymphocytic aggregates and parenchymal accumulation of macrophages in rats. EMSA demonstrated that smoke exposure enhanced NF-κB activation in rats' alveolar macrophages (AMs). Compared with the control group, smoke exposure induced a notable increase in TNF-α and IL-1β in BALF, lung tissues, and a decrease of β2-AR expression of AMs. The expression of β2-AR from AMs was inversely correlated with TNF-α and IL-1β levels of BALF. These data demonstrated that chronic smoke-triggered lung inflammation was accompanied by down-regulation of β2-AR in rat lungs' AMs.

  3. The alpha(1D)-adrenergic receptor directly regulates arterial blood pressure via vasoconstriction.

    PubMed

    Tanoue, Akito; Nasa, Yoshihisa; Koshimizu, Takaaki; Shinoura, Hitomi; Oshikawa, Sayuri; Kawai, Takayuki; Sunada, Sachie; Takeo, Satoshi; Tsujimoto, Gozoh

    2002-03-01

    To investigate the physiological role of the alpha(1D)-adrenergic receptor (alpha(1D)-AR) subtype, we created mice lacking the alpha(1D)-AR (alpha(1D)(-/-)) by gene targeting and characterized their cardiovascular function. In alpha(1D)-/- mice, the RT-PCR did not detect any transcript of the alpha(1D)-AR in any tissue examined, and there was no apparent upregulation of other alpha(1)-AR subtypes. Radioligand binding studies showed that alpha(1)-AR binding capacity in the aorta was lost, while that in the heart was unaltered in alpha(1D)-/- mice. Non-anesthetized alpha(1D)-/- mice maintained significantly lower basal systolic and mean arterial blood pressure conditions, relative to wild-type mice, and they showed no significant change in heart rate or in cardiac function, as assessed by echocardiogram. Besides hypotension, the pressor responses to phenylephrine and norepinephrine were decreased by 30-40% in alpha(1D)-/- mice. Furthermore, the contractile response of the aorta and the pressor response of isolated perfused mesenteric arterial beds to alpha(1)-AR stimulation were markedly reduced in alpha(1D)-/- mice. We conclude that the alpha(1D)-AR participates directly in sympathetic regulation of systemic blood pressure by vasoconstriction.

  4. beta-adrenergic receptor gene polymorphisms and beta-blocker treatment outcomes in hypertension.

    PubMed

    Pacanowski, M A; Gong, Y; Cooper-Dehoff, R M; Schork, N J; Shriver, M D; Langaee, T Y; Pepine, C J; Johnson, J A

    2008-12-01

    Numerous studies have demonstrated that beta(1)- and beta(2)-adrenergic receptor gene (ADRB1 and ADRB2) variants influence cardiovascular risk and beta-blocker responses in hypertension and heart failure. We evaluated the relationship between ADRB1 and ADRB2 haplotypes, cardiovascular risk (death, nonfatal myocardial infarction (MI), and nonfatal stroke), and atenolol-based vs. verapamil sustained-release (SR)-based antihypertensive therapy in 5,895 coronary artery disease (CAD) patients. After an average of 2.8 years, death rates were higher in patients carrying the ADRB1 Ser49-Arg389 haplotype (hazard ratio (HR) 3.66, 95% confidence interval (95% CI) 1.68-7.99). This mortality risk was significant in patients randomly assigned to verapamil SR (HR 8.58, 95% CI 2.06-35.8) but not atenolol (HR 2.31, 95% CI 0.82-6.55), suggesting a protective role for the beta-blocker. ADRB2 haplotype associations were divergent within the treatment groups but did not remain significant after adjustment for multiple comparisons. ADRB1 haplotype variation is associated with mortality risk, and beta-blockers may be preferred in subgroups of patients defined by ADRB1 or ADRB2 polymorphisms.

  5. Translational control of beta2-adrenergic receptor mRNA by T-cell-restricted intracellular antigen-related protein.

    PubMed

    Kandasamy, Karthikeyan; Joseph, Kusumam; Subramaniam, Kothandharaman; Raymond, John R; Tholanikunnel, Baby G

    2005-01-21

    Cellular expression of the beta(2)-adrenergic receptor (beta(2)-AR) is suppressed at the translational level by 3'-untranslated region (UTR) sequences. To test the possible role of 3'-UTR-binding proteins in translational suppression of beta(2)-AR mRNA, we expressed the full-length 3'-UTR or the adenylate/uridylate-rich (A+U-rich element (ARE)) RNA from the 3'-UTR sequences of beta(2)-AR in cell lines that endogenously express this receptor. Reversal of beta(2)-adrenergic receptor translational repression by retroviral expression of 3'-UTR sequences suggested that ARE RNA-binding proteins are involved in translational suppression of beta(2)-adrenergic receptor expression. Using a 20-nucleotide ARE RNA from the receptor 3'-UTR as an affinity ligand, we purified the proteins that bind to these sequences. T-cell-restricted intracellular antigen-related protein (TIAR) was one of the strongly bound proteins identified by this method. UV-catalyzed cross-linking experiments using in vitro transcribed 3'-UTR RNA and glutathione S-transferase-TIAR demonstrated multiple binding sites for this protein on beta(2)-AR 3'-UTR sequences. The distal 340-nucleotide region of the 3'-UTR was identified as a target RNA motif for TIAR binding by both RNA gel shift analysis and immunoprecipitation experiments. Overexpression of TIAR resulted in suppression of receptor protein synthesis and a significant shift in endogenously expressed beta(2)-AR mRNA toward low molecular weight fractions in sucrose gradient polysome fractionation. Taken together, our results provide the first evidence for translational control of beta(2)-AR mRNA by TIAR.

  6. Identification of New Agonists and Antagonists of the Insect Odorant Receptor Co-Receptor Subunit

    PubMed Central

    Chen, Sisi; Luetje, Charles W.

    2012-01-01

    Background Insects detect attractive and aversive chemicals using several families of chemosensory receptors, including the OR family of olfactory receptors, making these receptors appealing targets for the control of insects. Insect ORs are odorant-gated ion channels, comprised of at least one common subunit (the odorant receptor co-receptor subunit, Orco) and at least one variable odorant specificity subunit. Each of the many ORs of an insect species is activated or inhibited by an unique set of odorants that interact with the variable odorant specificity subunits, making the development of OR directed insect control agents complex and laborious. However, several N-,2-substituted triazolothioacetamide compounds (VUAA1, VU0450667 and VU0183254) were recently shown to act directly on the highly conserved Orco subunit, suggesting that broadly active compounds can be developed. We have explored the chemical space around the VUAA1 structure in order to identify new Orco ligands. Principal Findings We screened ORs from several insect species, using heterologous expression in Xenopus oocytes and an electrophysiological assay, with a panel of 22 compounds structurally related to VUAA1. By varying the nitrogen position in the pyridine ring and altering the moieties decorating the phenyl ring, we identified two new agonists and a series of competitive antagonists. Screening smaller compounds, similar to portions of the VUAA1 structure, also yielded competitive antagonists. Importantly, we show that Orco antagonists inhibit odorant activation of ORs from several insect species. Detailed examination of one antagonist demonstrated inhibition to be through a non-competitive mechanism. Conclusions A similar pattern of agonist and antagonist sensitivity displayed by Orco subunits from different species suggests a highly conserved binding site structure. The susceptibility to inhibition of odorant activation by Orco antagonism is conserved across disparate insect species

  7. Structural Insights into Conformational Stability of Wild-Type and Mutant β1-Adrenergic Receptor

    PubMed Central

    Balaraman, Gouthaman S.; Bhattacharya, Supriyo; Vaidehi, Nagarajan

    2010-01-01

    Abstract Recent experiments to derive a thermally stable mutant of turkey beta-1-adrenergic receptor (β1AR) have shown that a combination of six single point mutations resulted in a 20°C increase in thermal stability in mutant β1AR. Here we have used the all-atom force-field energy function to calculate a stability score to detect stabilizing point mutations in G-protein coupled receptors. The calculated stability score shows good correlation with the measured thermal stability for 76 single point mutations and 22 multiple mutants in β1AR. We have demonstrated that conformational sampling of the receptor for various mutants improve the prediction of thermal stability by 50%. Point mutations Y227A5.58, V230A5.61, and F338M7.48 in the thermally stable mutant m23-β1AR stabilizes key microdomains of the receptor in the inactive conformation. The Y227A5.58 and V230A5.61 mutations stabilize the ionic lock between R1393.50 on transmembrane helix3 and E2856.30 on transmembrane helix6. The mutation F338M7.48 on TM7 alters the interaction of the conserved motif NPxxY(x)5,6F with helix8 and hence modulates the interaction of TM2-TM7-helix8 microdomain. The D186-R317 salt bridge (in extracellular loops 2 and 3) is stabilized in the cyanopindolol-bound wild-type β1AR, whereas the salt bridge between D184-R317 is preferred in the mutant m23. We propose that this could be the surrogate to a similar salt bridge found between the extracellular loop 2 and TM7 in β2AR reported recently. We show that the binding energy difference between the inactive and active states is less in m23 compared to the wild-type, which explains the activation of m23 at higher norepinephrine concentration compared to the wild-type. Results from this work throw light into the mechanism behind stabilizing mutations. The computational scheme proposed in this work could be used to design stabilizing mutations for other G-protein coupled receptors. PMID:20643076

  8. 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

  9. Orexin receptor antagonists as therapeutic agents for insomnia.

    PubMed

    Equihua, Ana C; De La Herrán-Arita, Alberto K; Drucker-Colin, Rene

    2013-12-25

    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.

  10. [Mineralocorticoid receptor antagonists and therapeutic strategies of cardiovascular damage].

    PubMed

    Verdugo, Fernando J; Montellano, Felipe A; Carreño, Juan E; Marusic, Elisa T

    2014-01-01

    In recent years, much attention has focused on the role of aldosterone and mineralocorticoid receptors (MRs) in the pathophysiology of hypertension and cardiovascular disease. Patients with primary aldosteronism, in whom angiotensin II levels are low, have a higher incidence of cardiovascular complications than patients with essential hypertension. The Randomized Aldactone Evaluation Study (RALES) demonstrated that adding a non-specific MR antagonist, spironolactone, to a standard therapy that included angiotensin-converting enzyme (ACE) inhibitors, loop diuretics, and digoxin, significantly reduced morbidity and mortality in patients with moderate to severe heart failure. Similarly, the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS) showed that the addition of a selective MR antagonist (ARM), eplerenone, to an optimal medical therapy reduces morbidity and mortality among patients with acute myocardial infarction complicated by left ventricular dysfunction and heart failure. These data suggest that aldosterone induces cardiac injury through activation of MRs and support the notion that MR blockade has beneficial effects on aldosterone-dependent cardiac injury, through mechanisms that cannot be simply explained by hemodynamic changes. Although, MRA are highly effective in patients with heart failure, the risk of hyperkalemia should not be overlooked. Serious hyperkalemia events were reported in some MRA clinical trials; however these risks can be mitigated through appropriate patient selection, dose selection, patient education, monitoring, and follow-up.

  11. 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.

  12. Novel alpha1-adrenergic receptor signaling pathways: secreted factors and interactions with the extracellular matrix.

    PubMed

    Shi, Ting; Duan, Zhong-Hui; Papay, Robert; Pluskota, Elzbieta; Gaivin, Robert J; de la Motte, Carol A; Plow, Edward F; Perez, Dianne M

    2006-07-01

    alpha1-Adrenergic receptor (alpha1-ARs) subtypes (alpha1A, alpha1B, and alpha1D) regulate multiple signal pathways, such as phospholipase C, protein kinase C (PKC), and mitogen-activated protein kinases. We employed oligonucleotide microarray technology to explore the effects of both short- (1 h) and long-term (18 h) activation of the alpha1A-AR to enable RNA changes to occur downstream of earlier well characterized signaling pathways, promoting novel couplings. Polymerase chain reaction (PCR) studies confirmed that PKC was a critical regulator of alpha1A-AR-mediated gene expression, and secreted interleukin (IL)-6 also contributed to gene expression alterations. We next focused on two novel signaling pathways that might be mediated through alpha1A-AR stimulation because of the clustering of gene expression changes for cell adhesion/motility (syndecan-4 and tenascin-C) and hyaluronan (HA) signaling. We confirmed that alpha1-ARs induced adhesion in three cell types to vitronectin, an interaction that was also integrin-, FGF7-, and PKC-dependent. alpha1-AR activation also inhibited cell migration, which was integrin- and PKC-independent but still required secretion of FGF7. alpha1-AR activation also increased the expression and deposition of HA, a glycosaminoglycan, which displayed two distinct structures: pericellular coats and long cable structures, as well as increasing expression of the HA receptor, CD44. Long cable structures of HA can bind leukocytes, which this suggests that alpha1-ARs may be involved in proinflammatory responses. Our results indicate alpha1-ARs induce the secretion of factors that interact with the extracellular matrix to regulate cell adhesion, motility and proinflammatory responses through novel signaling pathways.

  13. 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.

  14. 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.

  15. Implementation of a fluorescence-based screening assay identifies histamine H3 receptor antagonists clobenpropit and iodophenpropit as subunit-selective N-methyl-D-aspartate receptor antagonists.

    PubMed

    Hansen, Kasper B; Mullasseril, Praseeda; Dawit, Sara; Kurtkaya, Natalie L; Yuan, Hongjie; Vance, Katie M; Orr, Anna G; Kvist, Trine; Ogden, Kevin K; Le, Phuong; Vellano, Kimberly M; Lewis, Iestyn; Kurtkaya, Serdar; Du, Yuhong; Qui, Min; Murphy, T J; Snyder, James P; Bräuner-Osborne, Hans; Traynelis, Stephen F

    2010-06-01

    N-Methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca(2+)-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal concentrations of glutamate and glycine to minimize detection of competitive antagonists. The assay is validated by successfully identifying known noncompetitive, but not competitive NMDA receptor antagonists among 1800 screened compounds from two small focused libraries, including the commercially available library of pharmacologically active compounds. Hits from the primary screen are validated through a secondary screen that used two-electrode voltage-clamp recordings on recombinant NMDA receptors expressed in Xenopus laevis oocytes. This strategy identified several novel modulators of NMDA receptor function, including the histamine H3 receptor antagonists clobenpropit and iodophenpropit, as well as the vanilloid receptor transient receptor potential cation channel, subfamily V, member 1 (TRPV1) antagonist capsazepine. These compounds are noncompetitive antagonists and the histamine H3 receptor ligand showed submicromolar potency at NR1/NR2B NMDA receptors, which raises the possibility that compounds can be developed that act with high potency on both glutamate and histamine receptor systems simultaneously. Furthermore, it is possible that some actions attributed to histamine H3 receptor inhibition in vivo may also involve NMDA receptor antagonism.

  16. Activation of a GTP-binding protein and a GTP-binding-protein-coupled receptor kinase (beta-adrenergic-receptor kinase-1) by a muscarinic receptor m2 mutant lacking phosphorylation sites.

    PubMed

    Kameyama, K; Haga, K; Haga, T; Moro, O; Sadée, W

    1994-12-01

    A mutant of the human muscarinic acetylcholine receptor m2 subtype (m2 receptor), lacking a large part of the third intracellular loop, was expressed and purified using the baculovirus/insect cell culture system. The mutant was not phosphorylated by beta-adrenergic-receptor kinase, as expected from the previous assignment of phosphorylation sites to the central part of the third intracellular loop. However, the m2 receptor mutant was capable of stimulating beta-adrenergic-receptor-kinase-1-mediated phosphorylation of a glutathione S-transferase fusion protein containing the m2 phosphorylation sites in an agonist-dependent manner. Both mutant and wild-type m2 receptors reconstituted with the guanine-nucleotide-binding regulatory proteins (G protein), G(o) and G(i)2, displayed guanine-nucleotide-sensitive high-affinity agonist binding, as assessed by displacement of [3H]quinuclidinyl-benzilate binding with carbamoylcholine, and both stimulated guanosine 5'-3-O-[35S]thiotriphosphate ([35S]GTP[S]) binding in the presence of carbamoylcholine and GDP. The Ki values of carbamoylcholine effects on [3H]quinuclidinyl-benzilate binding were indistinguishable for the mutant and wild-type m2 receptors. Moreover, the phosphorylation of the wild-type m2 receptor by beta-adrenergic-receptor kinase-1 did not affect m2 interaction with G proteins as assessed by the binding of [3H]quinuclidinyl benzilate or [35S]GTP[S]. These results indicate that (a) the m2 receptor serves both as an activator and as a substrate of beta-adrenergic-receptor kinase, and (b) a large part of the third intracellular loop of the m2 receptor does not contribute to interaction with G proteins and its phosphorylation by beta-adrenergic-receptor kinase does not uncouple the receptor and G proteins in reconstituted lipid vesicles.

  17. B2 adrenergic receptors and morphological changes of the enteric nervous system in colorectal adenocarcinoma

    PubMed Central

    Ciurea, Raluca Niculina; Rogoveanu, Ion; Pirici, Daniel; Târtea, Georgică-Costinel; Streba, Costin Teodor; Florescu, Cristina; Cătălin, Bogdan; Puiu, Ileana; Târtea, Elena-Anca; Vere, Cristin Constantin

    2017-01-01

    AIM To study the morphology of the enteric nervous system and the expression of beta-2 adrenergic (B2A) receptors in primary colorectal cancer. METHODS In this study, we included forty-eight patients with primary colorectal cancer and nine patients for control tissue from the excision of a colonic segment for benign conditions. We determined the clinicopathological features and evaluated the immunohistochemical expression pattern of B2A receptors as well as the morphological changes of the enteric nervous system (ENS). In order to assess statistical differences, we used the student t-test for comparing the means of two groups and one-way analysis of variance with Bonferroni’s post hoc analysis for comparing the means of more than two groups. Correlations were assessed using the Pearson’s correlation coefficient. RESULTS B2A receptors were significantly associated with tumor grading, tumor size, tumor invasion, lymph node metastasis (P < 0.05), while there were no statistically significant associations with gender, CRC location and gross appearance (P > 0.05). We observed, on one hand, a decrease of the relative area for both Auerbach and Meissner plexuses with the increase of the tumor grading, and on the other hand, an increase of the relative area of other nervous elements not in the Meissner plexus or in the Auerbach plexus with the tumor grading. For G1 tumors we found that epithelial B2A area showed an inverse correlation with the Auerbach plexus areas [r(14) = -0.531, P < 0.05], while for G2 tumors, epithelial B2A areas showed an indirect variation with both the Auerbach plexus areas [r(14) = -0.453, P < 0.05] and the Meissner areas [r(14) = -0.825, P < 0.01]. For G3 tumors, the inverse dependence increased for both Auerbach [r(14) = -0.587, P < 0.05] and Meissner [r(14) = -0.934, P < 0.05] plexuses. CONCLUSION B2A receptors play an important role in colorectal carcinogenesis and can be utilized as prognostic factors. Furthermore, study of the ENS in

  18. Involvement of tyrosine residues located in the carboxyl tail of the human beta 2-adrenergic receptor in agonist-induced down-regulation of the receptor.

    PubMed Central

    Valiquette, M; Bonin, H; Hnatowich, M; Caron, M G; Lefkowitz, R J; Bouvier, M

    1990-01-01

    Chronic exposure of various cell types to adrenergic agonists leads to a decrease in cell surface beta 2-adrenergic receptor (beta 2AR) number. Sequestration of the receptor away from the cell surface as well as a down-regulation of the total number of cellular receptors are believed to contribute to this agonist-mediated regulation of receptor number. However, the molecular mechanisms underlying these phenomena are not well characterized. Recently, tyrosine residues located in the cytoplasmic tails of several membrane receptors, such as the low density lipoprotein and mannose-6-phosphate receptors, have been suggested as playing an important role in the agonist-induced internalization of these receptors. Accordingly, we assessed the potential role of two tyrosine residues in the carboxyl tail of the human beta 2AR in agonist-induced sequestration and down-regulation of the receptor. Tyr-350 and Tyr-354 of the human beta 2AR were replaced with alanine residues by site-directed mutagenesis and both wild-type and mutant beta 2AR were stably expressed in transformed Chinese hamster fibroblasts. The mutation dramatically decreased the ability of the beta 2AR to undergo isoproterenol-induced down-regulation. However, the substitution of Tyr-350 and Tyr-354 did not affect agonist-induced sequestration of the receptor. These results suggest that tyrosine residues in the cytoplasmic tail of human beta 2AR are crucial determinants involved in its down-regulation. PMID:2164220

  19. Straub tail reaction in mice treated with σ(1) receptor antagonist in combination with methamphetamine.

    PubMed

    Kitanaka, Junichi; Kitanaka, Nobue; Hall, F Scott; Uhl, George R; Tanaka, Koh-Ichi; Nishiyama, Nobuyoshi; Takemura, Motohiko

    2012-10-30

    Straub tail reaction (STR) was observed in male ddY mice after simultaneous administration with BMY 14802 (a non-specific σ receptor antagonist) and methamphetamine (METH). The intensity and duration of STR depended on the dose of BMY 14802. The tail reaction was inhibited completely by (+)-SKF 10,047 (a putative σ(1) receptor agonist) and partially by PB 28 (a putative σ(2) receptor agonist). The STR was mimicked in mice treated with BD 1047 (a putative σ(1) receptor antagonist), but not SM-21, a putative σ(2) receptor antagonist, in combination with METH. STR evoked with BD 1047 plus METH was inhibited by (+)-SKF 10,047. STR induced by BMY 14802 and METH was abolished by naloxone (a relatively non-selective opioid receptor antagonist) or U-50,488H (a selective κ-agonist), suggesting that the STR may be mediated by activation of opioid receptor system.

  20. 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

  1. Alpha adrenergic modulation on effects of norepinephrine transporter inhibitor reboxetine in five-choice serial reaction time task

    PubMed Central

    Liu, Yia-Ping; Lin, Yu-Lung; Chuang, Chia-Hsin; Kao, Yu-Cheng; Chang, Shang-Tang; Tung, Che-Se

    2009-01-01

    The study examined the effects of a norepinephrine transporter (NET) inhibitor reboxetine (RBX) on an attentional performance test. Adult SD rats trained with five-choice serial reaction time task (5-CSRTT) were administered with RBX (0, 3.0 and 10 mg/kg) in the testing day. Alpha-1 adrenergic receptor antagonist PRA and alpha-2 adrenergic receptor antagonist RX821002 were used to clarify the RBX effect. Results revealed that rat received RBX at 10 mg/kg had an increase in the percentage of the correct response and decreases in the numbers of premature response. Alpha-1 adrenergic receptor antagonist Prazosin (PRA) at 0.1 mg/kg reversed the RBX augmented correct responding rate. However, alpha-2 adrenergic receptor antagonist RX821002 at 0.05 and 0.1 mg/kg dose dependently reversed the RBX reduced impulsive responding. Our results suggested that RBX as a norepinephrine transporter inhibitor can be beneficial in both attentional accuracy and response control and alpha-1 and alpha-2 adrenergic receptors might be involved differently. PMID:19678962

  2. 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.

  3. Inhibition of radiation-induced polyuria by histamine receptor antagonists

    SciTech Connect

    Donlon, M.A.; Melia, J.A.; Helgeson, E.A.; Wolfe, W.W.

    1986-03-01

    In previous studies the authors have demonstrated that gamma radiation results in polyuria, which is preceded by polydypsia. This suggests that the increased thirst elicited by radiation causes increased urinary volume (UV). Histamine, which is released following radiation exposure, also elicits drinking by nonirradiated rats when administered exogenously. In this study the authors have investigated both the role of water deprivation and the effect of histamine receptor antagonists (HRA) on radiation-induced polyuria. Sprague-Dawley rats were housed individually in metabolic cages. Water was allowed ad libitum except in deprivation experiments where water was removed for 24 hr immediately following radiation. Cimetidine (CIM), an H2 HRA, and dexbromopheniramine (DXB), an H1 HRA, were administered i.p. (16 and 1 mg/kg, respectively) 30 min prior to irradiation (950 rads from a cobalt source). UV was determined at 24-hr intervals for 3 days preceding irradiation and 24 hr postirradiation. UV in DXB treated rats was significantly reduced 24 hr postirradiation (CON = 427 +/- 54%; DXB = 247 +/- 39% of preirradiated CON) compared to postirradiation control values. CIM did not affect postirradiation UV. These data suggest that radiation-induced polyuria is caused by polydypsia which is, in part, mediated by histamine induced by an H1 receptor.

  4. 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

  5. Management of hyperkalaemia consequent to mineralocorticoid-receptor antagonist therapy.

    PubMed

    Roscioni, Sara S; de Zeeuw, Dick; Bakker, Stephan J L; Lambers Heerspink, Hiddo J

    2012-12-01

    Mineralocorticoid-receptor antagonists (MRAs) reduce blood pressure and albuminuria in patients treated with angiotensin-converting-enzyme inhibitors or angiotensin-II-receptor blockers. The use of MRAs, however, is limited by the occurrence of hyperkalaemia, which frequently occurs in patients older than 65 years with impaired kidney function, and/or diabetes. Patients with these characteristics might still benefit from MRA therapy, however, and should not be excluded from this treatment option. This limitation raises the question of how to optimize the therapeutic use of MRAs in this population of patients. Understanding the individual variability in patients' responses to MRAs, in terms of albuminuria, blood pressure and serum potassium levels, might lead to targeted intervention. MRA use might be restricted to patients with high levels of mineralocorticoid activity, evaluated by circulating renin and aldosterone levels or renal excretion of potassium. In addition, reviewing the patient's diet and concomitant medications might prove useful in reducing the risk of developing subsequent hyperkalaemia. If hyperkalaemia does develop, treatment options exist to decrease potassium levels, including administration of calcium gluconate, insulin, β(2)-agonists, diuretics and cation-exchange resins. In combination with novel aldosterone blockers, these strategies might offer a rationale with which to optimize therapeutic intervention and extend the population of patients who can benefit from use of MRAs.

  6. Histamine and histamine receptor antagonists in cancer biology.

    PubMed

    Blaya, Bruno; Nicolau-Galmés, Francesca; Jangi, Shawkat M; Ortega-Martínez, Idoia; Alonso-Tejerina, Erika; Burgos-Bretones, Juan; Pérez-Yarza, Gorka; Asumendi, Aintzane; Boyano, María D

    2010-07-01

    Histamine has been demonstrated to be involved in cell proliferation, embryonic development, and tumour growth. These various biological effects are mediated through the activation of specific histamine receptors (H1, H2, H3, and H4) that differ in their tissue expression patterns and functions. Although many in vitro and in vivo studies of the modulatory roles of histamine in tumour development and metastasis have been reported, the effect of histamine in the progression of some types of tumours remains controversial; however, recent findings on the role of histamine in the immune system have shed new light on this question. This review focuses on the recent advances in understanding the roles of histamine and its receptors in tumour biology. We report our recent observations of the anti-tumoural effect of H1 histamine antagonists on experimental and human melanomas. We have found that in spite of exogenous histamine stimulated human melanoma cell proliferation, clonogenic ability and migration activity in a dose-dependent manner, the melanoma tumour growth was not modulated by in vivo histamine treatment. On the contrary, terfenadine-treatment in vitro induced melanoma cell death by apoptosis and in vivo terfenadine treatment significantly inhibited tumour growth in murine models. These observations increase our understanding of cancer biology and may inspire novel anticancer therapeutic strategies.

  7. Slowing of shortening velocity of rat cardiac myocytes by adenosine receptor stimulation regardless of beta-adrenergic stimulation.

    PubMed Central

    Strang, K T; Mentzer, R M; Moss, R L

    1995-01-01

    1. Single ventricular myocytes were enzymatically isolated, incubated with the A1-purinergic and beta-adrenergic receptor-specific agonists N6-cyclopentyladenosine (CPA) and isoprenaline (Iso), and then rapidly skinned. Ca2+ sensitivity of isometric tension and unloaded shortening velocity (Vo) were measured, and protein kinase A (PKA)-specific phosphorylations of troponin I (TnI) and C-protein were assessed by back-phosphorylation of cell suspensions with [gamma-32P]-ATP. 2. Isoprenaline treatment decreased the Ca2+ sensitivity of isometric tension relative to propranolol-treated controls, as did simultaneous stimulation with Iso and CPA (Iso + CPA). CPA alone had no effect on Ca2+ sensitivity. Vo was greater in Iso-treated cells than in paired controls, while Vo was significantly less than control in both Iso + CPA-treated and CPA-treated cells. 3. Phosphorylation of TnI and C-protein was increased by Iso treatment and also when Iso and CPA were simultaneously applied. CPA alone caused a significant decrease in the phosphorylation state of these two proteins. 4. From these results we conclude that A1-purinergic receptor stimulation does not inhibit beta-adrenergic receptor-mediated phosphorylation of myofilament proteins, nor does it alter the Ca2+ sensitivity of isometric tension at the level of the myofilaments. However, A1-receptor stimulation does decrease Vo at the level of the myofilaments by a mechanism that is independent of beta-adrenergically mediated phosphorylation of TnI and C-protein. Images Figure 1 Figure 4 PMID:7473228

  8. Dynamic mass redistribution analysis of endogenous β-adrenergic receptor signaling in neonatal rat cardiac fibroblasts.

    PubMed

    Carter, Rhonda L; Grisanti, Laurel A; Yu, Justine E; Repas, Ashley A; Woodall, Meryl; Ibetti, Jessica; Koch, Walter J; Jacobson, Marlene A; Tilley, Douglas G

    2014-02-01

    Label-free systems for the agnostic assessment of cellular responses to receptor stimulation have been shown to provide a sensitive method to dissect receptor signaling. β-adenergic receptors (βAR) are important regulators of normal and pathologic cardiac function and are expressed in cardiomyocytes as well as cardiac fibroblasts, where relatively fewer studies have explored their signaling responses. Using label-free whole cell dynamic mass redistribution (DMR) assays we investigated the response patterns to stimulation of endogenous βAR in primary neonatal rat cardiac fibroblasts (NRCF). Catecholamine stimulation of the cells induced a negative DMR deflection resulting in a concentration-dependent pharmacological response that was competitively blocked by βAR blockade and non-competitively blocked by irreversible uncoupling of Gs proteins. Pharmacological profiling of subtype-selective βAR agonists and antagonists revealed a dominant role of β2AR in mediating the DMR responses, consistent with the relative expression levels of β2AR and β1AR in NRCF. Additionally, βAR-mediated cAMP generation was assessed via a fluorescence biosensor, revealing similar kinetics between DMR responses and cAMP generation. As such, βAR-dependent DMR responses were enhanced via inhibition of cAMP degradation, as well as dynamin-mediated receptor internalization. Finally, we assessed G protein-independent βAR signaling through epidermal growth factor receptor (EGFR). While inhibition of EGFR reduced the DMR response to βAR stimulation, our results demonstrate that G protein-dependent signaling produces a majority of the biological response to βAR stimulation in NRCF. Altogether, measurement of DMR responses in primary cardiac fibroblasts provides a sensitive readout for investigating endogenous βAR signaling via both G protein-dependent and -independent pathways.

  9. Use of Enterally Delivered Angiotensin II Type Ia Receptor Antagonists to Reduce the Severity of Colitis

    PubMed Central

    Okawada, Manabu; Koga, Hiroyuki; Larsen, Scott D.; Showalter, Hollis D.; Turbiak, Anjanette J.; Jin, Xiaohong; Lucas, Peter C.; Lipka, Elke; Hillfinger, John; Kim, Jae Seung

    2011-01-01

    Background Renin-angiotensin system blockade reduces inflammation in several organ systems. Having found a fourfold increase in angiotensin II type Ia receptor expression in a dextran sodium sulfate colitis model, we targeted blockade with angiotensin II type Ia receptor antagonists to prevent colitis development. Because hypotension is a major complication of angiotensin II type Ia receptor antagonists use, we hypothesized that use of angiotensin II type Ia receptor antagonists compounds which lack cell membrane permeability, and thus enteric absorption, would allow for direct enteral delivery at far higher concentrations than would be tolerated systemically, yet retain efficacy. Methods Based on the structure of the angiotensin II type Ia receptor antagonist losartan, deschloro-losartan was synthesized, which has extremely poor cell membrane permeability. Angiotensin II type Ia receptor antagonist efficacy was evaluated by determining the ability to block NF-κB activation in vitro. Dextran sodium sulfate colitis was induced in mice and angiotensin II type Ia receptor antagonist efficacy delivered transanally was assessed. Results In vitro, deschloro-losartan demonstrated near equal angiotensin II type Ia receptor blockade compared to losartan as well as another angiotensin II type Ia receptor antagonist, candesartan. In the dextran sodium sulfate model, each compound significantly improved clinical and histologic scores and epithelial cell apoptosis. Abundance of TNF-α, IL-1β, and IL6 mRNA were significantly decreased with each compound. In vitro and in vivo intestinal drug absorption, as well as measures of blood pressure and mucosal and colonic blood flow, showed significantly lower uptake of deschloro-losartan compared to losartan and candesartan. Conclusions This study demonstrated efficacy of high-dose angiotensin II type Ia receptor antagonists in this colitis model. We postulate that a specially designed angiotensin II type Ia receptor antagonist with

  10. Mechanism regulating proasthmatic effects of prolonged homologous beta2-adrenergic receptor desensitization in airway smooth muscle.

    PubMed

    Nino, Gustavo; Hu, Aihua; Grunstein, Judith S; Grunstein, Michael M

    2009-10-01

    Use of long-acting beta(2)-adrenergic receptor (beta2AR) agonists to treat asthma incurs an increased risk of asthma morbidity with impaired bronchodilation and heightened bronchoconstriction, reflecting the adverse effects of prolonged homologous beta2AR desensitization on airway smooth muscle (ASM) function. Since phosphodiesterase 4 (PDE4) regulates ASM relaxation and contractility, we examined whether the changes in ASM function induced by prolonged homologous beta2AR desensitization are attributed to altered expression and action of PDE4. Cultured human ASM cells and isolated rabbit ASM tissues exposed for 24 h to the long-acting beta2AR agonist salmeterol exhibited impaired acute beta2AR-mediated cAMP accumulation and relaxation, respectively, together with ASM constrictor hyperresponsiveness. These proasthmatic-like changes in ASM function were associated with upregulated PDE4 activity due to enhanced expression of the PDE4D5 isoform and were prevented by pretreating the ASM preparations with the PDE4 inhibitor rolipram or with inhibitors of either PKA or ERK1/2 signaling. Extended studies using gene silencing and pharmacological approaches demonstrated that: 1) the mechanism underlying upregulated PDE4D5 expression following prolonged beta2AR agonist exposure involves PKA-dependent activation of G(i) protein signaling via its betagamma-subunits, which elicits downstream activation of ERK1/2 and its induction of PDE4D5 transcription; and 2) the induction of PDE4 activity and consequent changes in ASM responsiveness are prevented by pretreating the beta2AR agonist-exposed ASM preparations with inhibitors of G(i)-betagamma signaling. Collectively, these findings identify that the proasthmatic changes in ASM function resulting from prolonged homologous beta2AR desensitization are attributed to upregulated PDE4 expression induced by G(i)-betagamma-mediated cross-talk between the PKA and ERK1/2 signaling pathways.

  11. Toxicity of select beta adrenergic receptor-blocking pharmaceuticals (B-blockers) on aquatic organisms.

    PubMed

    Huggett, D B; Brooks, B W; Peterson, B; Foran, C M; Schlenk, D

    2002-08-01

    One class of pharmaceutical compounds identified in U.S. and European waters are the B-adrenergic receptor blocking compounds (B-blockers). However, little information is available on the potential aquatic toxicity of these compounds. Therefore, Hyalella azteca, Daphnia magna, Ceriodaphnia dubia, and Oryias latipes (Japanese medaka) were exposed to metoprolol, nadolol, and propranolol to determine potential toxicity. Average 48-h LC(50) for propranolol to H. azteca was 29.8 mg/L. The no-observed-effects concentration (NOEC) and lowest-observed-effects concentration (LOEC) for propranolol affecting reproduction of H. azteca were 0.001 and 0.1 mg/L, respectively. The average propranolol and metoprolol 48-h LC(50)s for D. magna were 1.6 and 63.9 mg/L, respectively. C. dubia 48-h LC(50)s were 0.85 and 8.8 mg/L for propranolol and metoprolol, respectively. The NOEC and LOEC of propranolol affecting reproduction in C. dubia were 0.125 and 0.25 mg/L, respectively. In O. latipes, the propranolol 48-h LC(50) was 24.3 mg/L. Medaka growth was decreased at 0.5 mg/L propranolol. A 2-week medaka reproductive study indicated significant changes in plasma steroid levels; however, no changes in the average number of eggs produced or number of viable eggs which hatched was observed. In a 4-week follow-up propranolol exposure, the total number of eggs produced by medaka and the number of viable eggs that hatched were decreased at concentrations as low as 0.5 microg/L. Based on this study and the expected aqueous environmental exposure levels, adverse effects of propranolol to invertebrate populations is unlikely; however, further reproductive studies are need to elucidate the risk to teleosts.

  12. Anticonvulsive effect of nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Kuder, Kamil; Subramanian, Dhanasekaran; Shafiullah, Mohamed; Stark, Holger; Lażewska, Dorota; Adem, Abdu; Kieć-Kononowicz, Katarzyna

    2014-06-01

    To determine the potential of histamine H3 receptor (H3R) ligands as new antiepileptic drugs (AEDs), aromatic ether, and diether derivatives (1-12) belonging to the nonimidazole class of ligands, with high in-vitro binding affinity at human H3R, were tested for their in-vivo anticonvulsive activity in the maximal electroshock (MES)-induced and pentylenetetrazole (PTZ)-kindled seizure models in rats. The anticonvulsive effects of a systemic injection of 1-12 on MES-induced and PTZ-kindled seizures were evaluated against the reference AED phenytoin (PHT) and the structurally related H3R antagonist/inverse agonist pitolisant (PIT). Among the most promising ligands 2, 4, 5, and 11, there was a significant and dose-dependent reduction in the duration of tonic hind limb extension (THLE) in MES-induced seizure subsequent to administration of 4 and 5 [(5, 10, and 15 mg/kg, intraperitoneally (i.p.)]. The protective effects observed for the 1-(3-(3-(4-chlorophenyl)propoxy)propyl)-3-methylpiperidine derivative 11 at 10 mg/kg, i.p. were significantly greater than those of PIT, and were reversed by pretreatment with the central nervous system penetrant H1R antagonist pyrilamine (PYR) (10 mg/kg). Moreover, the protective action of the reference AED PHT, at a dose of 5 mg/kg (without considerable protection in the MES model), was significantly augmented when coadministered with derivative 11 (5 mg/kg, i.p.). Surprisingly, pretreatment with derivative 7 (10 mg/kg, i.p.), an ethylphenoxyhexyl-piperidine derivative without considerable protection in the MES model, potently altered PTZ-kindled seizure, significantly prolonged myoclonic latency time, and clearly shortened the total seizure time when compared with control, PHT, and PIT. These interesting results highlight the potential of H3R ligands as new AEDs or as adjuvants to available AED therapeutics.

  13. Development of adrenergic and cholinergic receptor cardiovascular regulatory capacity in the Canada goose (Branta canadensis) and domestic goose (Anser anser domesticus).

    PubMed

    Swart, Justin; Tate, Kevin; Crossley, Dane A

    2014-01-01

    Adrenergic control of cardiovascular function is a common component of regulation in embryonic birds studied to date. Our goal was to investigate adrenergic and cholinergic cardiovascular regulation in two goose species, the Canada goose (Branta canadensis) and the related domestic goose (Anser anser domesticus) to determine if these species possess similar regulation during embryonic development. We determined mean arterial pressure (Pm) and heart rate (fH) responses to serial blockade of cholinergic, β-adrenergic and α-adrenergic receptors in B. canadensis and A. domesticus at 70 and 90% of total incubation (28days). Both species possessed cholinergic and β-adrenergic tone on fH at 70% of incubation that increased in intensity with development. In addition, a constant α-adrenergic tone on Pm was present in both species. Our findings indicate that these geese species possess both cholinergic and adrenergic cardiovascular regulation providing information needed for speculation regarding the commonalities in the ontogeny of these cardiovascular regulatory elements in birds.

  14. Heterocyclic 1,7-disubstituted indole sulfonamides are potent and selective human EP3 receptor antagonists.

    PubMed

    Hategan, Georgeta; Polozov, Alexandre M; Zeller, Wayne; Cao, Hua; Mishra, Rama K; Kiselyov, Alex S; Ramirez, Jose; Halldorsdottir, Gudrún; Andrésson, Thornorkell; Gurney, Mark E; Singh, Jasbir

    2009-12-01

    We have developed a pharmacophore model for the EP(3) receptor antagonists based on its endogenous ligand PGE(2). This ligand-based design yielded a series of novel peri-substituted [4.3.0] bicyclic aromatics featuring 1-alklyaryl 7-heterocyclic sulfonamide substituents. The synthesized molecules are potent antagonists of human EP(3) receptor in vitro and show inhibition of rat platelets aggregation. Optimized derivatives display high selectivity over IP, FP, and other EP receptor panels.

  15. Mechanisms of Radiosensitization by the Neurotensin Receptor Antagonist SR48692 in Prostate Cancer Models

    DTIC Science & Technology

    2009-04-01

    Neurotensin Receptor Antagonist SR48692 in Prostate Cancer Models PRINCIPAL INVESTIGATOR: Jaroslaw Dziegielewski, Ph.D...Receptor Antagonist 5a. CONTRACT NUMBER SR48692 in Prostate Cancer Models 5b. GRANT NUMBER W81XWH-08-1-0114 5c. PROGRAM ELEMENT NUMBER 6...neurotensin receptor by SR48692 drug could sensitize cancer cells to radiation. SR48692 activity was measured in PC3, C42 and LNCaP prostate cancer

  16. The effects of histamine H3-receptor antagonists on amygdaloid kindled seizures in rats.

    PubMed

    Kakinoki, H; Ishizawa, K; Fukunaga, M; Fujii, Y; Kamei, C

    1998-07-15

    The effects of histamine H3-receptor antagonists, thioperamide, and clobenpropit on amygdaloid kindled seizures were investigated in rats. Both intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) injections of H3-antagonists resulted in a dose-related inhibition of amygdaloid kindled seizures. An inhibition induced by thioperamide was antagonized by an H3-agonist [(R)-alpha-methylhistamine] and H1-antagonists (diphenhydramine and chlorpheniramine). On the other hand, an H2-antagonist (cimetidine and ranitidine) caused no antagonistic effect. Metoprine, an inhibitor of N-methyltransferase was also effective in inhibiting amygdaloid kindled seizure, and this effect was augmented by thioperamide treatment.

  17. Development of selective agonists and antagonists of P2Y receptors

    PubMed Central

    Ivanov, Andrei A.; de Castro, Sonia; Harden, T. Kendall; Ko, Hyojin

    2008-01-01

    Although elucidation of the medicinal chemistry of agonists and antagonists of the P2Y receptors has lagged behind that of many other members of group A G protein-coupled receptors, detailed qualitative and quantitative structure–activity relationships (SARs) were recently constructed for several of the subtypes. Agonists selective for P2Y1, P2Y2, and P2Y6 receptors and nucleotide antagonists selective for P2Y1 and P2Y12 receptors are now known. Selective nonnucleotide antagonists were reported for P2Y1, P2Y2, P2Y6, P2Y11, P2Y12, and P2Y13 receptors. At the P2Y1 and P2Y12 receptors, nucleotide agonists (5′-diphosphate derivatives) were converted into antagonists of nanomolar affinity by altering the phosphate moieties, with a focus particularly on the ribose conformation and substitution pattern. Nucleotide analogues with conformationally constrained ribose-like rings were introduced as selective receptor probes for P2Y1 and P2Y6 receptors. Screening chemically diverse compound libraries has begun to yield new lead compounds for the development of P2Y receptor antagonists, such as competitive P2Y12 receptor antagonists with antithrombotic activity. Selective agonists for the P2Y4, P2Y11, and P2Y13 receptors and selective antagonists for P2Y4 and P2Y14 receptors have not yet been identified. The P2Y14 receptor appears to be the most restrictive of the class with respect to modification of the nucleobase, ribose, and phosphate moieties. The continuing process of ligand design for the P2Y receptors will aid in the identification of new clinical targets. PMID:18600475

  18. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%-80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  19. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists

    PubMed Central

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%–80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  20. Selective inhibition of beta(2)-adrenergic receptor-mediated cAMP generation by activation of the P2Y(2) receptor in mouse pineal gland tumor cells.

    PubMed

    Suh, B C; Kim, J S; Namgung, U; Han, S; Kim, K T

    2001-06-01

    Rhythmic noradrenergic signaling from the hypothalamic clock in the suprachiasmatic nucleus to the pineal gland causes an increase in intracellular cAMP which regulates the circadian fluctuation of melatonin synthesis. The activation of phospholipase C (PLC)-coupled P2Y(2) receptors upon treatment with ATP and UTP exclusively inhibited the isoproterenol-stimulated cAMP production in mouse pineal gland tumor cells. However, the activation of other PLC-coupled receptors including P2Y(1) and bombesin receptors had little or no effect on the isoproterenol-stimulated cAMP production. Also, ATP did not inhibit cAMP production caused by forskolin, prostaglandin E(2), or the adenosine analog NECA. These results suggest a selective coupling between signalings of P2Y(2) and beta(2)-adrenergic receptors. The binding of [(3)H]CGP12177 to beta(2)-adrenergic receptors was not effected by the presence of ATP or UTP. Ionomycin decreased the isoproterenol-stimulated cAMP production, whereas phorbol 12-myristate 13-acetate slightly potentiated the isoproterenol response. Chelation of intracellular Ca(2+), however, had little effect on the ATP-induced inhibition of cAMP production, while it completely reversed the ionomycin-induced inhibition. Treatment of cells with pertussis toxin almost completely blocked the inhibitory effect of nucleotides. Pertussis toxin also inhibited the nucleotide-induced increase in intracellular Ca(2+) and inositol 1,4,5-trisphosphate production by 30-40%, suggesting that the ATP-mediated inhibition of the cAMP generation and the partial activation of PLC are mediated by pertussis toxin-sensitive G(i)-protein. We conclude that one of the functions of P2Y(2) receptors on the pineal gland is the selective inhibition of beta-adrenergic receptor-mediated signaling pathways via the inhibitory G-proteins.

  1. Role of Adrenergic Receptors in Glucose, Fructose and Galactose-Induced Increases in Intestinal Glucose Uptake in Dogs.

    PubMed

    Salman, T M; Alada, A R A; Oyebola, D D O

    2014-12-29

    The study investigated the role of adrenergic receptors in glucose, fructose-, and galactose- induced increases in intestinal glucose uptake. Experiments were carried out on fasted male anaesthetized Nigerian local dogs divided into seven groups (with five dogs per group). Group I dogs were administered normal saline and served as control. Dogs in groups II, III and IV were intravenously infused with glucose (1.1 mg/kg/min), fructose (1.1 mg/kg/min) and galactose (1.1 mg/kg/min) respectively. Another three groups, V, VI and VII were pretreated with prazosin (0.2mg/kg), propranolol (0.5mg/kg) or a combination of prazosin (0.2mg/kg) and propranolol (0.5mg/kg) followed by glucose infusion, frutose infusion or galactose infusion respectively. Through a midline laparatomy, the upper jejunum was cannulated for blood flow measurement and blood samples were obtained for measurement of glucose content of the arterial blood and venous blood from the upper jejunal segment. Glucose uptake was calculated as the product of jejunal blood flow and the difference between arterial and venous glucose levels (A-V glucose). The results showed that pretreatment of the animal with prazosin had no effect on glucose and galactose induced increases in glucose uptake. However, pretreatment with propranolol completely abolished glucose, fructose and galactose-induced increases in intestinal glucose uptake. Prazosin also significantly reduced galactose-induced increase in intestinal glucose uptake. The results suggest that the increases in intestinal glucose uptake induced by glucose and fructose are mediated mostly by beta adrenergic receptors while that of galactose is mediated by both alpha and beta adrenergic receptors.

  2. 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

  3. Effect of β2-adrenergic receptor gene (ADRB2) 3′ untranslated region polymorphisms on inhaled corticosteroid/long-acting β2-adrenergic agonist response

    PubMed Central

    2012-01-01

    Background Evidence suggests that variation in the length of the poly-C repeat in the 3′ untranslated region (3′UTR) of the β2-adrenergic receptor gene (ADRB2) may contribute to interindividual variation in β-agonist response. However, methodology in previous studies limited the assessment of the effect of sequence variation in the context of poly-C repeat length. The objectives of this study were to design a novel genotyping method to fully characterize sequence variation in the ADRB2 3′UTR poly-C repeat in asthma patients treated with inhaled corticosteroid and long-acting β2-adrenergic agonist (ICS/LABA) combination therapy, and to analyze the effect of the poly-C repeat polymorphism on clinical response. Methods In 2,250 asthma patients randomized to treatment with budesonide/formoterol or fluticasone/salmeterol in a six-month study (AstraZeneca study code: SD-039-0735), sequence diversity in the ADRB2 poly-C repeat region was determined using a novel sequencing-based genotyping method. The relationship between the poly-C repeat polymorphism and the incidence of severe asthma exacerbations, and changes in pulmonary function and asthma symptoms from baseline to the average during the treatment period, were analyzed. Results Poly-C repeat genotypes were assigned in 97% (2,192/2,250) of patients. Of the 13 different poly-C repeat alleles identified, six alleles occurred at a frequency of >5% in one or more population in this study. The repeat length of these six common alleles ranged from 10 to 14 nucleotides. Twelve poly-C repeat genotypes were observed at a frequency of >1%. No evidence of an association between poly-C repeat genotype and the incidence of severe asthma exacerbations was observed. Patients’ pulmonary function measurements improved and asthma symptoms declined when treated with ICS/LABA combination therapy regardless of poly-C repeat genotype. Conclusions The extensive sequence diversity present in the poly-C repeat region of the ADRB2

  4. Alpha2-Adrenergic Receptors and Breast Tumor Stroma: A Novel Pathway Driving Breast Cancer Growth and Metastasis

    DTIC Science & Technology

    2015-10-01

    injected intraperitoneally (IP) with sterile saline or 10 µg/kg DEX beginning 2 days prior to injection of 2x105 tumor cells into a mammary fat pad and...IP) with sterile saline or 5 mg/kg salmeterol beginning 2 days prior to injection of 2x105 tumor cells into a mammary fat pad and continuing daily...74. 8. Wang Q, Lu R, Zhao J, Limbird LE. Arrestin serves as a molecular switch, linking endogenous alpha2-adrenergic receptor to SRC-dependent, but

  5. The effect of activation of central adrenergic receptors by clonidine on the excitability of the solitary tract neurons in cats.

    PubMed

    Lipski, J; Solnicka, E

    1976-01-01

    The effect of i.v. administered clonidine (10-15 mug/kg) on the evoked potential recorded in the dosal part of medulla oblongata, during carotid sinus nerve stimulation, was studied in chloralose-urethane anaesthetized cats. Clonidine influenced the amplitude and configuration of the evoked potential and the changes were parallel to the blood pressure depressor response. However, the blood pressure drops, evoked by i.v. infusion of papaverine, did not influence the potential. It is concluded that the synaptic transmission from the carotid sinus nerve to the second order neurons in the solatary tract area can be modulated by the clonidine-induced activation of central adrenergic receptors.

  6. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

    PubMed

    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

  7. 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.

  8. Antinociceptive effects of histamine H3 receptor antagonist in the preclinical models of pain in rats and the involvement of central noradrenergic systems.

    PubMed

    Hsieh, Gin C; Honore, Prisca; Pai, Madhavi; Wensink, Erica J; Chandran, Prasant; Salyers, Anita K; Wetter, Jill M; Zhao, Chen; Liu, Huaqing; Decker, Michael W; Esbenshade, Timothy A; Cowart, Marlon D; Brioni, Jorge D

    2010-10-01

    The histamine H(3) receptor is predominantly expressed in the central nervous system and plays a role in diverse physiological mechanisms. In the present study, the effects of GSK189254, a potent and selective H(3) antagonist, were characterized in preclinical pain models in rats. Systemic GSK189254 produced dose-dependent efficacy (ED(50)=0.77 mg/kg i.p.) in a rat model of monoiodoacetate (MIA) induced osteoarthritic (OA) pain as evaluated by hindlimb grip force. The role of H(3) receptors in regulating pain perception was further demonstrated using other structurally distinct H(3) antagonists. GSK189254 also displayed efficacy in a rat surrogate model indicative of central sensitization, namely phase 2 response of formalin-induced flinching, and attenuated tactile allodynia in the spinal nerve ligation model of neuropathic pain (ED(50)=1.5mg/kg i.p.). In addition, GSK189254 reversed persistent (CFA) (ED(50)=2.1mg/kg i.p,), whereas was ineffective in acute (carrageenan) inflammatory pain. When administered intrathecally (i.t.) to the lumbar spinal cord, GSK189254 produced robust effects in relieving the OA pain (ED(50)=0.0027 mg/kg i.t.). The systemic GSK189254 effect was completely reversed by the alpha-adrenergic receptor antagonist phentolamine (i.p. and i.t.) but not by the opioid receptor antagonist naloxone (i.p.). Furthermore, the i.t. GSK189254 effect was abolished when co-administered with phentolamine (i.t.). These results suggest that the spinal cord is an important site of action for H(3) antagonism and the effect can be associated with activation of the noradrenergic system. Our data also provide support that selective H(3) antagonists may represent a class of agents for the treatment of pain disorders.

  9. Effects of alpha-1 adrenergic receptor antagonist, terazosin, on cardiovascular functions in anaesthetised dogs.

    PubMed

    Sharma, R; Ahuja, V M; Fahim, M

    2004-12-01

    Initially a dose-response curve of phenylephrine was constructed at dose strengths of 1-16 microg/kg in a cumulative manner. Phenylephrine caused a significant rise in the mean arterial pressure, left ventricular systolic pressure, left ventricular contractility, stroke volume and a significant decline in the heart rate. Terazosin was administered in three selected doses of 10, 100 and 300 microg/kg. Following each dose of terazosin, dose-response curve of phenylephrine was constructed. Terazosin, per se, decreased the basal mean arterial pressure, left ventricular systolic pressure, left ventricular contractility and stroke volume significantly in a dose dependent manner with an increase in the heart rate with no significant change in the cardiac output. The baroreflex sensitivity at all the three doses remained unchanged. In conclusion, the present findings support the view that terazosin reduces the blood pressure in a physiologically more favorable manner by maintaining the neural integrity of the cardiovascular system.

  10. Preventing the stress-induced shift from goal-directed to habit action with a β-adrenergic antagonist.

    PubMed

    Schwabe, Lars; Höffken, Oliver; Tegenthoff, Martin; Wolf, Oliver T

    2011-11-23

    Stress modulates instrumental action in favor of habit processes that encode the association between a response and preceding stimuli and at the expense of goal-directed processes that learn the association between an action and the motivational value of the outcome. Here, we asked whether this stress-induced shift from goal-directed to habit action is dependent on noradrenergic activation and may therefore be blocked by a β-adrenoceptor antagonist. To this end, healthy men and women were administered a placebo or the β-adrenoceptor antagonist propranolol before they underwent a stress or a control procedure. Shortly after the stress or control procedure, participants were trained in two instrumental actions that led to two distinct food outcomes. After training, one of the food outcomes was selectively devalued by feeding participants to satiety with that food. A subsequent extinction test indicated whether instrumental behavior was goal-directed or habitual. As expected, stress after placebo rendered participants' behavior insensitive to the change in the value of the outcome and thus habitual. After propranolol intake, however, stressed participants behaved, same as controls, goal-directed, suggesting that propranolol blocked the stress-induced bias toward habit behavior. Our findings show that the shift from goal-directed to habitual control of instrumental action under stress necessitates noradrenergic activation and could have important clinical implications, particularly for addictive disorders.

  11. Peripheral 5-HT2-like receptors. Can they be classified with the available antagonists?

    PubMed Central

    Leff, P.; Martin, G. R.

    1986-01-01

    Interactions between 5-hydroxytryptamine (5-HT) and the so-called 5-HT2 receptor antagonists ketanserin, spiperone, trazodone and methysergide were studied in isolated preparations of the rabbit aorta, rat jugular vein, and rat caudal artery. Trazodone and spiperone were apparently simple competitive antagonists since they produced antagonism that was surmountable over the concentration range studied and, in each tissue, their apparent affinity appeared to be independent of the antagonist concentration. Furthermore, concentration-ratios obtained with the two antagonists in combination suggested that antagonism was additive, implying mutual competition with a single population of 5-HT receptors. Ketanserin was a non-surmountable antagonist of 5-HT in the rat caudal artery and methysergide demonstrated surmountable, competitive antagonism only in the rabbit aorta. Antagonist dissociation constants estimated for apparently competitive interactions showed that ketanserin, spiperone and trazodone expressed affinities which differed according to the tissue used. In the case of trazodone, affinity estimates differed by as much as 12 fold. These discrepancies were independent of the 5-HT receptor agonist used and could not be attributed to an inadequate equilibration of the antagonist. These results can be interpreted in two ways: either the receptors in the different tissues are heterogeneous or the antagonists used here must be considered as unreliable probes for the classification of 5-HT2-like receptors. PMID:2943354

  12. Thyroid hormone and adrenergic signaling interact to control pineal expression of the dopamine receptor D4 gene (Drd4).

    PubMed

    Kim, Jong-So; Bailey, Michael J; Weller, Joan L; Sugden, David; Rath, Martin F; Møller, Morten; Klein, David C

    2010-01-15

    Dopamine plays diverse and important roles in vertebrate biology, impacting behavior and physiology through actions mediated by specific G-protein-coupled receptors, one of which is the dopamine receptor D4 (Drd4). Here we present studies on the >100-fold daily rhythm in rat pineal Drd4 expression. Our studies indicate that Drd4 is the dominant dopamine receptor gene expressed in the pineal gland. The gene is expressed in pinealocytes at levels which are approximately 100-fold greater than in other tissues, except the retina, in which transcript levels are similar. Pineal Drd4 expression is circadian in nature and under photoneural control. Whereas most rhythmically expressed genes in the pineal are controlled by adrenergic/cAMP signaling, Drd4 expression also requires thyroid hormone. This advance raises the questions of whether Drd4 expression is regulated by this mechanism in other systems and whether thyroid hormone controls expression of other genes in the pineal gland.

  13. Excitatory drive onto dopaminergic neurons in the rostral linear nucleus is enhanced by norepinephrine in an α1 adrenergic receptor-dependent manner.

    PubMed

    Williams, Megan A; Li, Chia; Kash, Thomas L; Matthews, Robert T; Winder, Danny G

    2014-11-01

    Dopaminergic innervation of the extended amygdala regulates anxiety-like behavior and stress responsivity. A portion of this dopamine input arises from dopamine neurons located in the ventral lateral periaqueductal gray (vlPAG) and rostral (RLi) and caudal linear nuclei of the raphe (CLi). These neurons receive substantial norepinephrine input, which may prime them for involvement in stress responses. Using a mouse line that expre