DOE Office of Scientific and Technical Information (OSTI.GOV)

Raulli, R.; Crews, F.T.

The potency of various alpha adrenergic compounds on stimulation of phosphatidylinositol (PI) hydrolysis was determined using (/sup 3/H)-inositol labelled cerebral cortical slices. Norepinephrine-induced PI hydrolysis was inhibited by the alpha/sub 1/ selective antagonist prazosin (1 ..mu..M) but not the beta receptor antagonist propranolol (1 ..mu..M). Tramazoline, (-)-ephedrine, and (+/-)-phenylpropanolamine were all found to be partial agonists at 1 mM concentrations. Clonidine, naphazoline, trazodone, and the novel antidepressant mianserin at concentrations of 100 ..mu..M to 1 mM produced no significant increase in PI hydrolysis above control levels. The relationship between responses and receptor binding will be discussed.

Characterization of the hypothermic effect of the synthetic cannabinoid HU-210 in the rat. Relation to the adrenergic system and endogenous pyrogens.

PubMed

Ovadia, H; Wohlman, A; Mechoulam, R; Weidenfeld, J

1995-02-01

In the present study we have characterized the hypothermic effect of the psychoactive cannabinoid HU-210, by investigating its interaction with the endogenous pyrogens, IL-1 and PGE2. We also studied the involvement of the adrenergic system in mediation of this hypothermic effect. Injection of HU-210 directly into the preoptic area caused a dose dependent reduction of rectal temperature from 37 to 32.1 degrees C. Injection of the non-psychoactive analog, HU-211 which does not bind to brain cannabinoid receptor, did not affect body temperature. Injection of the adrenergic agonists, CGP-12177 and clonidine (beta, and alpha adrenergic agonists, respectively) abrogated the hypothermia induced by HU-210. Injection of the adrenergic antagonists, prazosin (alpha 1) and propranolol (beta) enhanced the hypothermic effect of HU-210. Intracerebral administration of IL-1 or PGE2 to rats pretreated with HU-210 caused a transient inhibition of the hypothermia. The ex vivo rate of basal or bacterial endotoxin-induced synthesis of PGE2 by different brain regions, including the preoptic area was not affected by HU-210 administration. These results suggest that the synthetic cannabinoid HU-210 acts in the preoptic area, probably via the brain cannabinoid receptor to induce hypothermia. The hypothermic effect can be antagonized by adrenergic agonists and enhanced by adrenergic antagonists. HU-210 does not interfere with the pyrogenic effect of IL-1 or PGE2.

Interaction between Antagonist of Cannabinoid Receptor and Antagonist of Adrenergic Receptor on Anxiety in Male Rat.

PubMed

Komaki, Alireza; Abdollahzadeh, Fatemeh; Sarihi, Abdolrahman; Shahidi, Siamak; Salehi, Iraj

2014-01-01

Anxiety is among the most common and treatable mental disorders. Adrenergic and cannabinoid systems have an important role in the neurobiology of anxiety. The elevated plus-maze (EPM) has broadly been used to investigate anxiolytic and anxiogenic compounds. The present study investigated the effects of intraperitoneal (IP) injection of cannabinoid CB1 receptor antagonist (AM251) in the presence of alpha-1 adrenergic antagonist (Prazosin) on rat behavior in the EPM. In this study, the data were obtained from male Wistar rat, which weighing 200- 250 g. Animal behavior in EPM were videotaped and saved in computer for 10 min after IP injection of saline, AM251 (0.3 mg/kg), Prazosin (0.3 mg/kg) and AM251 + Prazosin, subsequently scored for conventional indices of anxiety. During the test period, the number of open and closed arms entries, the percentage of entries into the open arms of the EPM, and the spent time in open and closed arms were recorded. Diazepam was considered as a positive control drug with anxiolytic effect (0.3, 0.6, 1.2 mg/kg). Diazepam increased the number of open arm entries and the percentage of spent time on the open arms. IP injection of AM251 before EPM trial decreased open arms exploration and open arm entry. Whereas, Prazosin increased open arms exploration and open arm entry. This study showed that both substances in simultaneous injection have conflicting effects on the responses of each of these two compounds in a single injection. Injection of CB1 receptor antagonist may have an anxiogenic profile in rat, whereas adrenergic antagonist has an anxiolytic effect. Further investigations are essential for better understanding of anxiolytic and anxiogenic properties and neurobiological mechanisms of action and probable interactions of the two systems.

Noradrenaline inhibits lipopolysaccharide-induced tumor necrosis factor and interleukin 6 production in human whole blood.

PubMed Central

van der Poll, T; Jansen, J; Endert, E; Sauerwein, H P; van Deventer, S J

1994-01-01

Sepsis and lipopolysaccharide (LPS) trigger the systemic release of both cytokines and catecholamines. Cytokines are known to be capable of eliciting a stress hormone response in vivo. The present study sought insight into the effect of noradrenaline on LPS-induced release of tumor necrosis factor alpha (TNF) and interleukin 6 (IL-6) in human whole blood. Whole blood was incubated with LPS for 4 h at 37 degrees C in the presence and absence of noradrenaline and/or specific alpha and beta antagonists and agonists. Noradrenaline caused a dose-dependent inhibition of LPS-induced TNF and IL-6 production. This effect could be completely prevented by addition of the specific beta 1, antagonist metoprolol, while it was not affected by the alpha antagonist phentolamine. Specific beta-adrenergic stimulation by isoprenaline mimicked the inhibiting effect of noradrenaline on LPS-evoked cytokine production, whereas alpha-adrenergic stimulation by phenylephrine had no effect. Fluorescence-activated cell sorter analysis demonstrated that beta-adrenergic stimulation had no effect on LPS binding to and internalization into mononuclear cells or on the expression of CD14, the major receptor for LPS on mononuclear cells. In acute sepsis, enhanced release of noradrenaline may be part of a negative feedback mechanism meant to inhibit ongoing TNF and IL-6 production. PMID:8168970

Identification and characterization of (/sup 3/H)-rauwolscine binding to alpha2-adrenoceptors in the canine saphenous vein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gout, B.

1988-01-01

The biochemical exploration of the alpha2-adrenergic receptors was investigated in the canine saphenous vein using the highly selective alpha2-adrenergic antagonist rauwolscine as a tritiated ligand. Following an enzymatic digestive pretreatment, the authors isolated a purified smooth muscle cell membranes fraction from saphenous veins in quantity sufficient to permit them to study the venous alpha2-adrenoreceptor content. The binding of tritiated rauwolscine was rapid, specific, saturable and reversible. The presence of high affinity sites with a density of binding Bmax of 125.2 /+ -/ 43.1 fmol/mg protein was demonstrated on a unique class of non interacting sites. The kinetically derived Kd wasmore » 1.28 nM, in good agreement with the value obtained from saturation isotherms. The pharmacological profile of these sites was assessed by the comparison of the potency of alpha-adrenergic agonists and antagonists to inhibit 1 nM (/sup 3/H)-rauwolscine. Their efficacy was respectively: rauwolscine > phentolamine > RX 781094 > clonidine >> prazosin > (-)-phenylephrine > (-)-noradrenaline. The results showed that (/sup 3/H)-rauwolscine bound specifically to sites in their membranal preparation, which had the pharmacological characteristics of the alpha2-adrenoceptors. The correlation between biochemical and pharmacological data revealed the usefulness of binding methods in the further study of adrenergic mechanisms in the canine saphenous vein.« less

Alpha1-adrenergic drugs affect the development and expression of ethanol-induced behavioral sensitization.

PubMed

Kim, Andrezza Kyunmi; Souza-Formigoni, Maria Lucia Oliveira

2013-11-01

According to the incentive sensitization theory, addiction is caused primarily by drug-induced sensitization in the brain mesocorticolimbic systems. After repeated ethanol administration, some animals develop psychomotor sensitization, a phenomenon which occurs simultaneously with the incentive sensitization. Recent evidence suggests the involvement of norepinephrine (NE) in drug addiction, with a critical role in the ethanol reinforcing properties. In this study we evaluated the influence of an agonist (phenylephrine) and an antagonist (prazosin) of alpha1-adrenergic receptors on the development and expression of behavioral sensitization to ethanol. Male Swiss mice, previously treated with ethanol or saline, were challenged with the combined administration of ethanol (or saline) with alpha1-adrenergic drugs. Prazosin (0.1; 0.5 and 1.0 mg/kg) and phenylephrine (1.0 and 2.0 mg/kg) administration blocked the expression of behavioral sensitization to ethanol. In another set of experiments, mice treated with 0.5mg/kg of prazosin+ethanol did not present the development of behavioral sensitization. However, when challenged with ethanol alone, they showed the same sensitized levels of locomotor activity of those presented by mice previously treated with ethanol and saline. Phenylephrine (1.0 mg/kg) treatment did not affect the development of behavioral sensitization. Based on this data, we concluded that the alteration of alpha1-adrenergic receptors functioning, by the administration agonists or antagonists, affected the locomotor sensitization to the stimulant effect of ethanol, suggesting that the normal functioning of the noradrenergic system is essential to its development and expression. Copyright © 2013 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nomura, S.; Enna, S.J.

Tricyclic antidepressants (TCAs) have anticholinergic and ..cap alpha..-adrenergic blocking properties. The present study was undertaken to examine the effects of amitriptyline, imipramine, and desipramine on inositol phosphate accumulation, a brain second messenger system associated with cholinergic and adrenergic receptors. Whereas the TCAs were 28 to 400-fold weaker than atropine as inhibitors of /sup 3/H-QNB binding to brain cholinergic receptors, they were 600 to 2000-fold less active than atropine as inhibitors of carbachol-stimulated IP accumulation in brain. In contrast, the relative potencies of the TCAs and prazosin to inhibit norepinephrine-stimulated IP accumulation and /sup 3/H-prazosin binding appeared to be similar inmore » the two assays. The results suggest pharmacological differences between the cholinergic receptors labeled in the ONB binding assay and those mediating the IP response, whereas the ..cap alpha../sub 1/-adrenergic receptors appear to be similar in the two systems. Since atropine is considered a nonselective muscarinic antagonist, it is possible that the TCAs may differentiate between cholinergic receptor subtypes, which may be an important component of their clinical response.« less

In vitro study on the effects of some selected agonists and antagonists of alpha(1)-adrenergic receptors on the contractility of the aneurysmally-changed aortic smooth muscle in humans.

PubMed

Gnus, J; Czerski, A; Ferenc, S; Zawadzki, W; Witkiewicz, W; Hauzer, W; Rusiecka, A; Bujok, J

2012-02-01

The study included 18 sections of the aneurysmally-changed abdominal aortas, obtained from patients of the Provincial Specialist Hospital in Wroclaw and 18 sections of normal abdominal aortas obtained from swine. The collected samples were placed horizontally in the incubation chamber. Changes in their transverse section area were registered. They were stretched to a tension of 5 mN. Krebs-Henseleit buffer was used as the incubatory environment. Incubation of the sections was performed at a temperature of 37°C, in the gaseous mixture of oxygen and carbon dioxide used in the following proportion: 95% of O(2) and 5% of CO(2). Contractions of the aorta were registered with isotonic transducers (Letica Scientific Instruments). In the studies, we examined the influence of α(1)-adrenergic receptors (and their subtypes α(1A), α(1B), α(1D)) on the contractility of the aortic muscle in humans and swine by their stimulation or inhibition with some selected agonists or antagonists. This time, it was shown that the stimulation of α(1)-adrenergic receptors leads to contractions of the human and swine aortic muscle; the observed increase in the muscle tone may follow from the stimulation of all subtypes of alpha-1 receptor (α(1A), α(1B), α(1D)). All three subtypes of 1-adrenergic receptor are engaged in vasoconstriction, especially of α(1A) and α(1D) subtypes; the α(1B) subtype is less significant for aortic contractility. The contractile response of the aneurysmally-changed abdominal aorta in humans to agonists of α-adrenergic receptors was significantly less intense than that of the normal porcine aorta. It can be concluded that aneurysms influence the contractile response of the aorta.

Differential regulation of the cell cycle by alpha1-adrenergic receptor subtypes.

PubMed

Gonzalez-Cabrera, Pedro J; Shi, Ting; Yun, June; McCune, Dan F; Rorabaugh, Boyd R; Perez, Dianne M

2004-11-01

Alpha(1)-Adrenergic receptors have been implicated in growth-promoting pathways. A microarray study of individual alpha(1)-adrenergic receptor subtypes (alpha(1A), alpha(1B), and alpha(1D)) expressed in Rat-1 fibroblasts revealed that epinephrine altered the transcription of several cell cycle regulatory genes in a direction consistent with the alpha(1A)- and alpha(1D)-adrenergic receptors mediating G(1)-S cell cycle arrest and the alpha(1B-)mediating cell-cycle progression. A time course indicated that in alpha(1A) cells, epinephrine stimulated a G(1)-S arrest, which began after 8 h of stimulation and maximized at 16 h, at which point was completely blocked with cycloheximide. The alpha(1B)-adrenergic receptor profile also showed unchecked cell cycle progression, even under low serum conditions and induced foci formation. The G(1)-S arrest induced by alpha(1A)- and alpha(1D)-adrenergic receptors was associated with decreased cyclin-dependent kinase-6 and cyclin E-associated kinase activities and increased expression of the cyclin-dependent kinase inhibitor p27(Kip1), all of which were blocked by prazosin. There were no differences in kinase activities and/or expression of p27(Kip1) in epinephrine alpha(1B)-AR fibroblasts, although the microarray did indicate differences in p27(Kip1) RNA levels. Cell counts proved the antimitotic effect of epinephrine in alpha(1A) and alpha(1D) cells and indicated that alpha(1B)-adrenergic receptor subtype expression was sufficient to cause proliferation of Rat-1 fibroblasts independent of agonist stimulation. Analysis in transfected PC12 cells also confirmed the alpha(1A)- and alpha(1B)-adrenergic receptor effect. The alpha(1B)-subtype native to DDT1-MF2 cells, a smooth muscle cell line, caused progression of the cell cycle. These results indicate that the alpha(1A)- and alpha(1D)-adrenergic receptors mediate G(1)-S cell-cycle arrest, whereas alpha(1B)-adrenergic receptor expression causes a cell cycle progression and may induce transformation in sensitive cell lines.

A Placebo-Controlled Augmentation Trial of Prazosin for Combat Trauma PTSD

DTIC Science & Technology

2012-06-01

controlled trial to evaluate the efficacy and tolerability of the alpha-1 adrenergic antagonist, prazosin, for reducing trauma nightmares and sleep...efficacy and tolerability of the alpha-1 adrenergic antagonist prazosin compared to placebo for combat stress- related nightmares, sleep disturbance

Potentiation by adrenaline of human platelet activation and the inhibition by the alpha-adrenergic antagonist nicergoline of platelet adhesion, secretion and aggregation.

PubMed

Lanza, F; Cazenave, J P; Beretz, A; Sutter-Bay, A; Kretz, J G; Kieny, R

1986-08-01

Adrenaline (1 to 10 microM) can induce the aggregation of human platelets suspended in citrated plasma but does not induce the aggregation of washed human platelets at doses as high as 1 mM, although these platelets respond normally to ADP, PAF-acether, collagen, arachidonic acid, thrombin, the endoperoxide analog U-46619 and the Ca2+ ionophore A23187. Adrenaline (0.5 microM) potentiates the aggregation and secretion induced by all the previous agonists in citrated platelet-rich plasma (cPRP) or in washed platelets. The activation by adrenaline of human platelets is mediated by alpha 2-adrenergic receptors, as demonstrated by inhibition with a series of adrenergic antagonists. The alpha-adrenergic antagonist nicergoline inhibits the activation of human platelets by adrenaline in the following situations: nicergoline inhibits the aggregation and secretion caused by adrenaline in cPRP (IC50 0.22 microM and 0.28 microM respectively); nicergoline inhibits the aggregation and secretion induced by the combination of adrenaline and each aggregating agent listed above in cPRP (IC50 ranging from 0.1 to 2.5 microM) or in washed platelets (IC50 ranging from 0.1 to 0.8 microM); nicergoline inhibits the binding of 3H-yohimbine to washed human platelets (IC50 0.26 microM); the intravenous administration of nicergoline (0.5 mg/kg per day) to patients inhibits significantly the ex vivo response of their platelets to adrenaline in cPRP. High concentrations of nicergoline also inhibit the aggregation and secretion induced by the aggregating agents listed above in cPRP (IC50 range 108 to 670 microM) and in washed platelets (IC50 range 27 to 140 microM) and the adhesion of platelets to collagen-coated surfaces. This latter effect is not mediated through blockade of alpha-adrenoceptors. A possible role of adrenaline in platelet activation in vivo could justify the use of nicergoline (Sermion), an alpha-adrenergic antagonist in combination therapy to prevent arterial thrombosis.

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Involvement of adrenal hormones in tissue respiration of sub-tropical hibernating and non-hibernating species of frogs.

PubMed

Gupta, B B; Mahanta, A

1997-03-01

Effects of norepinephrine (NE), epinephrine (EP), corticosterone and cortisol were studied both in vivo and in vitro on the rate of oxygen consumption of tissues (liver, skeletal muscle and kidney) of sub-tropical Indian frogs Rana limnocharis (a hibernating species) and Rana cyanophlyctis (a non-hibernating species) exposed to natural climatic conditions during winter and summer/rainy seasons. Further, the effects of NE and EP were also studied in vitro in the presence of specific beta- and alpha-adrenergic antagonists (propranolol and prazosin). NE, EP and corticosterone, when administered in vivo or in vitro, significantly stimulated the respiratory rate of the tissues of both the species irrespective of the seasons/temperature. Results suggest that NE, EP and corticosterone are directly involved in regulation of the energy metabolism of both hibernating and non-hibernating species of sub-tropical frogs. The calorigenic action of NE and EP seems to be mediated by both beta- and alpha-adrenergic receptors. However, the temporal involvement of beta- and alpha-adrenergic receptors seems to be tissue-dependent.

Clebopride enhances contractility of the guinea pig stomach by blocking peripheral D2 dopamine receptor and alpha-2 adrenoceptor.

PubMed

Takeda, K; Taniyama, K; Kuno, T; Sano, I; Ishikawa, T; Ohmura, I; Tanaka, C

1991-05-01

The mechanism of action of clebopride on the motility of guinea pig stomach was examined by the receptor binding assay for bovine brain membrane and by measuring gastric contractility and the release of acetylcholine from the stomach. The receptor binding assay revealed that clebopride bound to the D2 dopamine receptor with a high affinity and to the alpha-2 adrenoceptor and 5-HT2 serotonin receptor with relatively lower affinity, and not to D1 dopamine, alpha-1 adrenergic, muscarinic acetylcholine, H1 histamine, or opioid receptor. In strips of the stomach, clebopride at 10(-8) M to 10(-5) M enhanced the electrical transmural stimulation-evoked contraction and the release of acetylcholine. This enhancement was attributed to the blockade of the D2 dopamine receptor and alpha-2 adrenoceptor because: 1) Maximum responses obtained with specific D2 dopamine receptor antagonist, domperidone, and with specific alpha-2 adrenoceptor antagonist, yohimbine, were smaller than that with clebopride, and the sum of the effects of these two specific receptor antagonists is approximately equal to the effect of clebopride. 2) The facilitatory effect of clebopride was partially eliminated by pretreatment of the sample with domperidone or yohimbine, and the facilitatory effect of clebopride was not observed in preparations treated with the combination of domperidone and yohimbine. Clebopride also antagonized the inhibitory effects of dopamine and clonidine on the electrical transmural stimulation-evoked responses. These results indicate that clebopride acts on post ganglionic cholinergic neurons at D2 and alpha-2 receptors in this preparation to enhance enteric nervous system stimulated motility.

Effects of the pesticide amitraz and its metabolite BTS 27271 on insulin and glucagon secretion from the perfused rat pancreas: involvement of alpha2D-adrenergic receptors.

PubMed

Abu-Basha, E A; Yibchok-Anun, S; Hopper, D L; Hsu, W H

1999-11-01

The study purpose was to investigate the direct effect of amitraz, a formamidine insecticide/acaricide, and its active metabolite BTS 27271 on insulin and glucagon secretion from the perfused rat pancreas. Amitraz and BTS 27271 (0.01, 0.1, 1, and 10 micromol/L) inhibited insulin secretion in a concentration-dependent manner. Amitraz increased glucagon secretion at 10 micromol/L, whereas BTS 27271 increased glucagon secretion at 1 and 10 micromol/L. Amitraz- and BTS 27271-induced decreases in insulin secretion and increases in glucagon secretion were not abolished during the 10-minute washout period. During the arginine treatment, both amitraz and BTS 27271 groups (0.1, 1, and 10 micromol/L) had lower insulin secretion and higher glucagon secretion than the control group. Idazoxan, an alpha2A/2D-adrenergic receptor (AR) antagonist, prevented the inhibitory effect of amitraz on insulin secretion in a concentration-dependent manner, but prazosin, an alpha1- and alpha2B/2C-AR antagonist, failed to antagonize the effect of amitraz. These results demonstrate that (1) amitraz and BTS 27271 inhibit insulin and stimulate glucagon secretion from the perfused rat pancreas, (2) amitraz inhibits insulin secretion by activation of alpha2D-ARs, since rats have alpha2D- but not alpha2A-ARs, and (3) amitraz and BTS 27271 may have a high binding affinity to the alpha2D-ARs of pancreatic islets.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Sevilla, J.A.; Zis, A.P.; Hollingsworth, P.J.

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 themore » number of these receptors.« less

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

PubMed Central

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

2002-01-01

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

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

PubMed

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

2002-12-01

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

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

PubMed

Bellantuono, Vito; Cassano, Giuseppe; Lippe, Claudio

2008-08-01

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

Dexmedetomidine improves neurologic outcome from incomplete ischemia in the rat. Reversal by the alpha 2-adrenergic antagonist atipamezole.

PubMed

Hoffman, W E; Kochs, E; Werner, C; Thomas, C; Albrecht, R F

1991-08-01

Dexmedetomidine is an alpha 2-adrenergic agonist that decreases central sympathetic activity and reduces the anesthetic requirement for halothane. We evaluated the effect of dexmedetomidine on neurologic and histopathologic outcome from incomplete cerebral ischemia in the rat. Anesthesia was maintained with a 25-micrograms.kg-1.h-1 fentanyl infusion combined with 70% nitrous oxide. Incomplete ischemia was produced by unilateral carotid artery ligation combined with hemorrhagic hypotension to 35 mmHg for 30 min. Arterial blood gas tensions, pH, and head temperature were maintained at normal levels during the experiment. Four ischemic groups were tested: group 1 (n = 15) received an intraperitoneal (ip) saline injection (control); group 2 (n = 10) received an ip injection of 10 micrograms/kg dexmedetomidine 30 min before ischemia; group 3 (n = 10) received 100 micrograms/kg dexmedetomidine; and group 4 (n = 10) received 100 micrograms/kg dexmedetomidine plus 1 mg/kg atipamezole (an alpha 2-adrenergic antagonist). Neurologic outcome was evaluated for 3 days using a graded deficit score. Histopathology was evaluated in coronal section in caudate and hippocampal tissue segments. Dexmedetomidine (10 and 100 micrograms/kg) significantly decreased plasma catecholamines and improved neurologic and histopathologic outcome in a dose-dependent manner compared to control rats (P less than 0.05). Atipamezole abolished the decrease in catecholamines and the improvement in outcome seen with dexmedetomidine, confirming that these effects were mediated by alpha 2-adrenergic receptors. It is concluded that alpha 2-adrenoreceptor stimulation decreases sympathetic activity and decreases ischemic injury in a model of incomplete cerebral ischemia.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, K.S.

Norepinephrine has previously been demonstrated by this laboratory to potentiate the in vitro T-dependent antibody response through the stimulation of {beta}-adrenergic receptors. The role of {beta}-adrenergic receptor subtypes in norepinephrine-induced potentiation of the antibody responses was examined with selective {beta}-adrenergic antagonists. The antagonists were metoprolol ({beta}{sub 1}-selective), ICI 118-551 ({beta}{sub 2}-selective), and propranolol ({beta}-non-selective). Both propranolol and ICI 118-551 blocked norepinephrine-induced potentiation of the antibody response, but metoprolol was ineffective. Receptor binding competition of antagonists with the radioligant, ({sup 3}H)CGP-12177 was examined and results were analyzed with the computer program, LIGAND. Competition by ICI 118-551 identified 75% {beta}{sub 2}- andmore » 25% {beta}{sub 1}-adrenergic receptors on splenic mononuclear cells. Enriched T lymphocytes exhibited 75% {beta}{sub 2}-adrenergic receptors, while enriched B lymphocytes contained 90% {beta}{sub 2}-adrenergic receptors as identified by ICI 118-551. Greater than twice as many total receptors were identified on B lymphocytes than T lymphocytes. A T cell lymphoma contained about 60% {beta}{sub 2}-receptors, while 100% were {beta}{sub 2} receptors on a B cell lymphoma, as assessed by ICI 118-551. Results support a heterogeneous {beta}-adrenergic receptor population on T lymphocytes and a more homogeneous {beta}{sub 2}-population on B lymphocytes.« less

The effect of timolol maleate on the disruption of the blood-aqueous barrier in the rabbit eye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmdahl, G.; Bengtsson, E.

1981-06-01

A disruption of the blood-aqueous barrier in rabbit eyes was elicited by use of topical prostaglandin E2(PGE2), infrared irradiation of the iris, or by subcutaneous alpha-melanocyte-stimulating hormone (alpha-MSH). The aqueous flare provoked was measured quantitatively with a photoelectric instrument. The effect of the (topical) beta-adrenergic antagonist timolol maleate on the breakdown of the blood-aqueous barrier was tested. Timolol applied topically in very large doses had no effect on exogenously administered PGE2. However, even in a very small concentration applied topically, timolol reduced the flare response to both infrared irradiation and alpha-MSH. These results support the theory that the effect ofmore » alpha-MSH and infrared irradiation on the blood-aqueous barrier is dependent on intact beta-adrenergic receptor sites.« less

Expression of nuclear proto-oncogenes in isoproterenol-induced cardiac hypertrophy.

PubMed

Brand, T; Sharma, H S; Schaper, W

1993-11-01

Rat hearts infused with the beta-adrenergic agonist isoproterenol were examined for the expression of several nuclear proto-oncogenes (c-fos, fosB, c-jun, junB, and junD) and the immediate early gene Egr-1. During the first 24 h after the start of infusion, a strong but transient expression of c-fos was observed. Expression of c-jun and junD were not elevated whereas junB was. By using specific antagonists to the alpha- (prazosin) and beta-adrenergic receptor (propranolol), a beta-adrenoceptor-specific blockade of the isoproterenol-mediated nuclear response was demonstrated. In situ hybridization localized c-fos expression to cardiac myocytes. Labelling was distributed focally in the left and right ventricles, and was strong and homogeneous in the atria. In contrast to beta-adrenergic stimulation, alpha-adrenoceptor stimulation with phenylephrine and norepinephrine caused the induction of c-jun and Egr-1 in addition to the proto-oncogenes induced by isoproterenol. Thus distinct programs of early response gene expression were expressed in response to alpha- versus beta-adrenergic stimulation.

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.

Evidence that the human cutaneous venoarteriolar response is not mediated by adrenergic mechanisms

NASA Technical Reports Server (NTRS)

Crandall, C. G.; Shibasaki, M.; Yen, T. C.

2002-01-01

The venoarteriolar response causes vasoconstriction to skin and muscle via local mechanisms secondary to venous congestion. The purpose of this project was to investigate whether this response occurs through alpha-adrenergic mechanisms. In supine individuals, forearm skin blood flow was monitored via laser-Doppler flowmetry over sites following local administration of terazosin (alpha(1)-antagonist), yohimbine (alpha(2)-antagonist), phentolamine (non-selective alpha-antagonist) and bretylium tosylate (inhibits neurotransmission of adrenergic nerves) via intradermal microdialysis or intradermal injection. In addition, skin blood flow was monitored over an area of forearm skin that was locally anaesthetized via application of EMLA (2.5 % lidocaine (lignocaine) and 2.5 % prilocaine) cream. Skin blood flow was also monitored over adjacent sites that received the vehicle for the specified drug. Each trial was performed on a minimum of seven subjects and on separate days. The venoarteriolar response was engaged by lowering the subject's arm from heart level such that the sites of skin blood flow measurement were 34 +/- 1 cm below the heart. The arm remained in this position for 2 min. Selective and non-selective alpha-adrenoceptor antagonism and presynaptic inhibition of adrenergic neurotransmission did not abolish the venoarteriolar response. However, local anaesthesia blocked the venoarteriolar response without altering alpha-adrenergic mediated vasoconstriction. These data suggest that the venoarteriolar response does not occur through adrenergic mechanisms as previously reported. Rather, the venoarteriolar response may due to myogenic mechanisms associated with changes in vascular pressure or is mediated by a non-adrenergic, but neurally mediated, local mechanism.

β-Adrenergic Receptor Mediation of Stress-Induced Reinstatement of Extinguished Cocaine-Induced Conditioned Place Preference in Mice: Roles for β1 and β2 Adrenergic Receptors

PubMed Central

Vranjkovic, Oliver; Hang, Shona; Baker, David A.

2012-01-01

Stress can trigger the relapse of drug use in recovering cocaine addicts and reinstatement in rodent models through mechanisms that may involve norepinephrine release and β-adrenergic receptor activation. The present study examined the role of β-adrenergic receptor subtypes in the stressor-induced reinstatement of extinguished cocaine-induced (15 mg/kg i.p.) conditioned place preference in mice. Forced swim (6 min at 22°C) stress or activation of central noradrenergic neurotransmission by administration of the selective α2 adrenergic receptor antagonist 2-[(4,5-dihydro-1H-imidazol-2-yl)methyl]-2,3-dihydro-1-methyl-1H-isoindole (BRL-44,408) (10 mg/kg i.p.) induced reinstatement in wild-type, but not β- adrenergic receptor-deficient Adrb1/Adrb2 double-knockout, mice. In contrast, cocaine administration (15 mg/kg i.p.) resulted in reinstatement in both wild-type and β-adrenergic receptor knockout mice. Stress-induced reinstatement probably involved β2 adrenergic receptors. The β2 adrenergic receptor antagonist -(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol (ICI-118,551) (1 or 2 mg/kg i.p.) blocked reinstatement by forced swim or BRL-44,408, whereas administration of the nonselective β-adrenergic receptor agonist isoproterenol (2 or 4 mg/kg i.p.) or the β2 adrenergic receptor-selective agonist clenbuterol (2 or 4 mg/kg i.p.) induced reinstatement. Forced swim-induced, but not BRL-44,408-induced, reinstatement was also blocked by a high (20 mg/kg) but not low (10 mg/kg) dose of the β1 adrenergic receptor antagonist betaxolol, and isoproterenol-induced reinstatement was blocked by pretreatment with either ICI-118,551 or betaxolol, suggesting a potential cooperative role for β1 and β2 adrenergic receptors in stress-induced reinstatement. Overall, these findings suggest that targeting β-adrenergic receptors may represent a promising pharmacotherapeutic strategy for preventing drug relapse, particularly in cocaine addicts whose drug use is stress related. PMID:22593095

Safety and efficacy of silodosin for the treatment of benign prostatic hyperplasia

PubMed Central

Yoshida, Masaki; Kudoh, Junzo; Homma, Yukio; Kawabe, Kazuki

2011-01-01

Lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) are highly prevalent in older men. Medical therapy is the first-line treatment for LUTS associated with BPH. Mainstays in the treatment of male LUTS and clinical BPH are the α1-adrenergic receptor antagonists. Silodosin is a new α1-adrenergic receptor antagonist that is selective for the α1A-adrenergic receptor. By antagonizing α1A-adrenergic receptors in the prostate and urethra, silodosin causes smooth muscle relaxation in the lower urinary tract. Since silodosin has greater affinity for the α1A-adrenergic receptor than for the α1B-adrenergic receptor, it minimizes the propensity for blood pressure-related adverse effects caused by α1B-adrenergic receptor blockade. In the clinical studies, patients receiving silodosin at a total daily dose of 8 mg exhibited significant improvements in the International Prostate Symptom Score and maximum urinary flow rate compared with those receiving placebo. Silodosin showed early onset of efficacy for both voiding and storage symptoms. Furthermore, long-term safety of silodosin was also demonstrated. Retrograde or abnormal ejaculation was the most commonly reported adverse effect. The incidence of orthostatic hypotension was low. In conclusion, silodosin, a novel selective α1A-adrenergic receptor antagonist, was effective in general and without obtrusive side effects. This review provides clear evidence in support of the clinical usefulness of silodosin in the treatment of LUTS associated with BPH. PMID:21753871

Endothelin-like action of Pausinystalia yohimbe aqueous extract on vascular and renal regional hemodynamics in Sprague Dawley rats.

PubMed

Ajayi, A A; Newaz, M; Hercule, H; Saleh, M; Bode, C O; Oyekan, A O

2003-12-01

The bark of the African tree Pausinystalia yohimbe has been used as a food additive with aphrodisiac and penile erection enhancing properties. The effect of an aqueous extract of P. yohimbe (CCD-X) on renal circulation was assessed in order to test the hypothesis that it possesses additional effects on nitric oxide production and/or endothelin-1 (ET-1)-like actions. In vivo studies with CCD-X in Sprague Dawley rats demonstrated a dose-dependent (1-1000 ng/kg) increase in mean blood pressure (p < 0.001) and an increase in medullary blood flow (MBF) (p < 0.001). Both the pressor action and renal medullary vasodilation were blocked by endothelinA (ETA) receptor antagonist BMS182874 and endothelinB (ETB) receptor antagonist BQ788 in combination. L-Nomega-nitro-l-arginine methyl ester (L-NAME; 10 mg/kg) also inhibited the increase in MBF induced by CCD-X. In vitro studies in isolated perfused kidney and in pressurized renal microvessels confirmed the dose-dependent vasoconstrictor action of this extract. ETA receptor antagonist BQ610 and ETB receptor antagonist BQ788 separately and significantly attenuated the renal vasoconstrictor actions of the extract (p < 0.001 ANOVA). These preliminary observations indicate that, in addition to the alpha-adrenergic antagonist actions that characterize yohimbine, CCD-X possesses endothelin-like actions and affects nitric oxide (NO) production in renal circulation. These findings suggest a strong possibility of post-receptor cross-talk between alpha2-adrenoceptors and endothelin, as well as a direct effect of alpha2-adrenoceptors on renal NO production. (c) 2003 Prous Science

N-substituted imidazolines and ethylenediamines and their action on alpha- and beta-adrenergic receptors.

PubMed

Hamada, A; Yaden, E L; Horng, J S; Ruffolo, R R; Patil, P N; Miller, D D

1985-09-01

A series of N-substituted imidazolines and ethylenediamines were synthesized and examined for their activity in alpha- and beta-adrenergic systems. The length of the intermediate side chain between the catechol and imidazoline ring or the amine of the ethylenediamine segment was shown to affect the adrenergic activity. N-[2-(3,4-Dihydroxyphenyl)ethyl]imidazoline hydrochloride (2) and N-[2-(3,4-dihydroxyphenyl)ethyl]ethylenediamine dihydrochloride (4), both with two methylene groups between the catechol and amine segment, were found to be somewhat selective for alpha 2-adrenergic receptors while 1-(3,4-dihydroxybenzyl)imidazoline hydrochloride (1) and N-2-(3,4-dihydroxybenzyl)ethylenediamine dihydrochloride (3), both with one methylene group between the catechol and amine segment, were more selective for alpha1-adrenergic receptors in a pithed rat model. Of the four compounds examined, only compound 2 showed significant direct activity on beta1- and beta2-adrenergic receptors.

Combining the α1-Adrenergic Receptor Antagonist, Prazosin, with the β-Adrenergic Receptor Antagonist, Propranolol, Reduces Alcohol Drinking More Effectively Than Either Drug Alone

PubMed Central

Rasmussen, Dennis D; Beckwith, Lauren E; Kincaid, Carrie L; Froehlich, Janice C

2014-01-01

Background Evidence suggests that activation of the noradrenergic system may contribute to alcohol drinking in animals and humans. Our previous studies demonstrated that blocking α1-adrenergic receptors with the antagonist, prazosin, decreased alcohol drinking in rats under various conditions. Since noradrenergic activation is also regulated by β-adrenergic receptors, we now examine the effects of the β-adrenergic receptor antagonist, propranolol, alone or in combination with prazosin, on alcohol drinking in rats selectively bred for high voluntary alcohol intake and alcohol preference (P line). Methods Two studies were conducted with male P rats. In study one, rats were allowed to become alcohol-dependent during 14 weeks of ad libitum access to food, water and 20% alcohol and the effect of propranolol (5–15 mg/kg, IP) and prazosin (1–2 mg/kg, IP) on alcohol intake during withdrawal were assessed. In study two, the effect of propranolol (5 mg/kg, IP) and prazosin (2 mg/kg, IP) on alcohol intake following prolonged imposed abstinence was assessed. Results Alcohol drinking following propranolol treatment was variable, but the combination of propranolol + prazosin consistently suppressed alcohol drinking during both alcohol withdrawal and following prolonged imposed abstinence, and the combination of these two drugs was more effective than was treatment with either drug alone. Conclusions Treatment with prazosin + propranolol, or a combination of other centrally active α1- and β-adrenergic receptor antagonists, may assist in preventing alcohol relapse in some individuals. PMID:24891220

Developmental changes in the role of a pertussis toxin sensitive guanine nucleotide binding protein in the rat cardiac alpha sub 1 -adrenergic system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, H.M.

1989-01-01

During development, the cardiac alpha{sub 1}-adrenergic chronotropic response changes from positive in the neonate to negative in the adult. This thesis examined the possibility of a developmental change in coupling of a PT-sensitive G-protein to the alpha{sub 1}-adrenergic receptor. Radioligand binding experiments performed with the iodinated alpha{sub 1}-selective radioligand ({sup 125}I)-I-2-({beta}-(4-hydroxphenyl)ethylaminomethyl)tetralone (({sup 125}I)-IBE 2254) demonstrated that the alpha{sub 1}-adrenergic receptor is coupled to a G-protein in both neonatal and adult rat hearts. However, in the neonate the alpha{sub 1}-adrenergic receptor is coupled to a PT-insensitive G-protein, whereas in the adult the alpha{sub 1}-adrenergic receptor is coupled to both a PT-insensitivemore » and a PT-sensitive G-protein. Consistent with the results from binding experiments, PT did not have any effect on the alpha{sub 1}-mediated positive chronotropic response in the neonate, whereas in the adult the alpha{sub 1}-mediated negative chronotropic response was completely converted to a positive one after PT-treatment. This thesis also examined the possibility of an alteration in coupling of the alpha{sub 1}-adrenergic receptor to its effector under certain circumstances such as high potassium (K{sup +}) depolarization in nerve-muscle (NM) co-cultures, a system which has been previously shown to be a convenient in vitro model to study the mature inhibitory alpha{sub 1}-response.« less

α1-Adrenergic receptor downregulates hepatic FGF21 production and circulating FGF21 levels in mice.

PubMed

Nonogaki, Katsunori; Kaji, Takao

2017-01-18

Fibroblast growth factor 21 (FGF21) is primarily secreted by the liver as an endocrine hormone and is suggested as a promising target for the treatment of metabolic diseases. FGF21 acts centrally to exert its effects on energy expenditure and body weight via the sympathetic nervous system in mice. Here we show that intraperitoneal injection of phentolamine (an α-adrenergic receptor antagonist, 5mg/kg) significantly increased plasma FGF21 levels compared with the saline controls in C57BL6J mice, whereas alprenolol (a β-adrenergic receptor antagonist, 6mg/kg) had no effect. In addition, intraperitoneal injection of prazosin (an α1-adrenergic receptor antagonist, 5mg/kg) significantly increased plasma FGF21 levels compared with the controls, whereas yohimbine (an α2-adrenergic receptor antagonist, 5mg/kg) had no effect. Moreover, the treatment with prazosin significantly increased the expression of hepatic FGF21, while having no effect on the expression of hepatic PPARα and PPARγ. After a 5-h fast, intraperitoneal injection of prazosin significantly increased plasma FGF21 levels and impaired glucose tolerance compared with controls. These findings suggest that α1-adrenergic receptor downregulates the expression of hepatic FGF21 and plasma FGF21 levels independently of feeding and hepatic PPARα and PPARγ expression in mice, and that the increases in circulating FGF21 levels might be related to impaired glucose tolerance. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Stimulation of spinal dorsal horn β2-adrenergic receptor ameliorates neuropathic mechanical hypersensitivity through a reduction of phosphorylation of microglial p38 MAP kinase and astrocytic c-jun N-terminal kinase.

PubMed

Zhang, Fang Fang; Morioka, Norimitsu; Abe, Hiromi; Fujii, Shiori; Miyauchi, Kazuki; Nakamura, Yoki; Hisaoka-Nakashima, Kazue; Nakata, Yoshihiro

2016-12-01

The noradrenaline-adrenergic system has a crucial role in controlling nociceptive transduction at the spinal level. While α-adrenergic receptors are known to regulate nociceptive neurotransmitter release at the spinal presynaptic level, it is not entirely clear whether β-adrenergic receptors are involved in controlling pain transduction at the spinal level as well. The current study elucidated a role of β-adrenergic receptors in neuropathic pain in mice following a partial sciatic nerve ligation (PSNL). In addition, the cellular and intracellular signaling cascade induced by β-adrenergic receptors in neuropathic mice was elaborated. Intrathecal injection of isoproterenol (1 nmol), a nonselective β-adrenergic receptor agonist, briefly ameliorated hind paw mechanical hypersensitivity of PSNL mice. Isoproterenol's antinociceptive effect was mediated through β2-adrenergic receptors since pretreatment with ICI118551, a selective β2-adrenergic receptor antagonist, but not with CGP20712A, a selective β1-adrenergic receptor antagonist, significantly attenuated isoproterenol's effect. Furthermore, intrathecal treatment with a selective β2-adrenergic receptor agonist, terbutaline, but not a selective β1-adrenergic receptor agonist, dobutamine, also significantly ameliorated neuropathic pain. Fourteen days after PSNL, increased phosphorylation of both p38 Mitogen-activated protein kinase (MAPK) in microglia and c-jun N-terminal kinase (JNK) in astrocytes of ipsilateral spinal dorsal horn were observed. Phosphorylation of both microglial p38 MAPK and astrocytic JNK were downregulated by stimulation of the β2-adrenergic receptor. Together, these results suggest that spinal β2-adrenergic receptor have an inhibitory role in neuropathic nociceptive transduction at the spinal level through a downregulation of glial activity, perhaps through modulation of MAP kinases phosphorylation. Thus, targeting of β2-adrenergic receptors could be an effective therapeutic strategy in treating neuropathic pain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Endogenous circulating sympatholytic factor in orthostatic intolerance

NASA Technical Reports Server (NTRS)

Shapiro, R. E.; Winters, B.; Hales, M.; Barnett, T.; Schwinn, D. A.; Flavahan, N.; Berkowitz, D. E.

2000-01-01

Sympathotonic orthostatic hypotension (SOH) is an idiopathic syndrome characterized by tachycardia, hypotension, elevated plasma norepinephrine, and symptoms of orthostatic intolerance provoked by assumption of an upright posture. We studied a woman with severe progressive SOH with blood pressure unresponsive to the pressor effects of alpha(1)-adrenergic receptor (AR) agonists. We tested the hypothesis that a circulating factor in this patient interferes with vascular adrenergic neurotransmission. Preincubation of porcine pulmonary artery vessel rings with patient plasma produced a dose-dependent inhibition of vasoconstriction to phenylephrine in vitro, abolished vasoconstriction to direct electrical stimulation, and had no effect on nonadrenergic vasoconstrictive stimuli (endothelin-1), PGF-2alpha (or KCl). Preincubation of vessels with control plasma was devoid of these effects. SOH plasma inhibited the binding of an alpha(1)-selective antagonist radioligand ([(125)I]HEAT) to membrane fractions derived from porcine pulmonary artery vessel rings, rat liver, and cell lines selectively overexpressing human ARs of the alpha(1B) subtype but not other AR subtypes (alpha(1A) and alpha(1D)). We conclude that a factor in SOH plasma can selectively and irreversibly inhibit adrenergic ligand binding to alpha(1B) ARs. We propose that this factor contributes to a novel pathogenesis for SOH in this patient. This patient's syndrome represents a new disease entity, and her plasma may provide a unique tool for probing the selective functions of alpha(1)-ARs.

Bucindolol, a nonselective beta 1- and beta 2-adrenergic receptor antagonist, decreases beta-adrenergic receptor density in cultured embryonic chick cardiac myocyte membranes.

PubMed

Asano, K; Zisman, L S; Yoshikawa, T; Headley, V; Bristow, M R; Port, J D

2001-06-01

Bucindolol and carvedilol, nonselective beta1- and beta2-adrenergic receptor antagonists, have been widely used in clinical therapeutic trials of congestive heart failure. The aim of the current study was to investigate long-term effects of bucindolol or carvedilol on beta-adrenergic receptor protein and gene expression in cardiac myocytes. Embryonic chick cardiac myocytes were cultured and incubated with bucindolol (1 microM), carvedilol (1 microM), or norepinephrine (1 microM) for 24 h. 125I-iodocyanopindolol binding assays demonstrated that incubation with norepinephrine or bucindolol, but not carvedilol, significantly decreased beta-adrenergic receptor density in crude membranes prepared from the myocytes. Neither bucindolol nor carvedilol significantly stimulated adenylyl cyclase activity in membranes from drug-untreated cells. Unlike by norepinephrine, the receptor density reduction by bucindolol incubation was not accompanied by a change in beta1-adrenergic receptor messenger RNA abundance. A decrease in membrane beta-adrenergic receptor density without a change in cognate messenger RNA abundance was also observed in hamster DDT1 MF2 cell line incubated with bucindolol (1 microM, 24 h). We conclude that incubation with bucindolol, but not carvedilol, results in true reduction of beta-adrenergic receptor density in chick cardiac myocyte membranes by mechanisms that are distinct from those responsible for receptor density reduction by the agonist norepinephrine.

Propranolol blocks the stimulatory effects of naloxone on ventilation and oxygen consumption in hamsters.

PubMed

Schlenker, E H; Eikanger, J

1997-06-01

The purposes of these studies were: 1) to determine the effects of various doses of propranolol, a nonspecific beta-adrenergic antagonist, on ventilation, oxygen consumption, and body temperature in hamsters, and 2) to test the hypothesis that in hamsters the stimulatory effects of naloxone, an opioid receptor antagonist, on ventilation and oxygen consumption occur, at least in part, through the release of catecholamines that act via beta-adrenergic receptors. Propranolol, a non-specific beta adrenergic receptor antagonist, at a 20 mg/kg depressed body temperature, oxygen consumption, tidal volume, and ventilation relative to saline. The lower dose of 10 mg/kg had only transitory effects on tidal volume at 60 min and ventilation at 30 min post-injection-Naloxone (1 mg/kg) relative to saline stimulated ventilation and oxygen consumption. These effects were blocked by propranolol pretreatment. The results of these experiments demonstrate that in the hamster, 1) body temperature, oxygen consumption, and ventilation appear to be modulated by beta-adrenergic receptors, and 2) the stimulatory effects of naloxone on oxygen consumption and ventilation may occur through the interaction of endogenous opioids and beta-adrenergic receptor systems.

Evidence for Alpha Receptors in the Human Ureter

NASA Astrophysics Data System (ADS)

Madeb, Ralph; Knopf, Joy; Golijanin, Dragan; Bourne, Patricia; Erturk, Erdal

2007-04-01

An immunohistochemical and western blot expression analysis of human ureters was performed in order to characterize the alpha-1-adrenergic receptor distribution along the length of the human ureteral wall. Mapping the distribution will assist in understanding the potential role alpha -1-adrenergic receptors and their subtype density might have in the pathophysiology of ureteral colic and stone passage. Patients diagnosed with renal cancer or bladder cancer undergoing nephrectomy, nephroureterectomy, or cystectomy had ureteral specimens taken from the proximal, mid, distal and tunneled ureter. Tissues were processed for fresh frozen examination and fixed in formalin. None of the ureteral specimens were involved with cancer. Serial histologic sections and immunohistochemical studies were performed using antibodies specific for alpha-1-adrenergic receptor subtypes (alpha 1a, alpha 1b, alpha 1d). The sections were examined under a light microscope and scored as positive or negative. In order to validate and quantify the alpha receptor subtypes along the human ureter. Western blotting techniques were applied. Human ureter stained positively for alpha -1-adrenergic receptors. Immunostaining appeared red, with intense reaction in the smooth muscle of the ureter and endothelium of the neighboring blood vessels. There was differential expression between all the receptors with the highest staining for alpha-1D subtype. The highest protein expression for all three subtypes was in the renal pelvis and decreased with advancement along the ureter to the distal ureter. At the distal ureter, there was marked increase in expression as one progressed towards the ureteral orifice. The same pattern of protein expression was exhibited for all three alpha -1-adrenergic receptor subtypes. We provide preliminary evidence for the ability to detect and quantify the alpha-1-receptor subtypes along the human ureter which to the best of our knowledge has never been done with immunohistochemistry and molecular techniques. These findings may lend support to the preliminary studies of the effectiveness of alpha-receptor blockade on ureteral colic and stone passage.

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

PubMed

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

2016-08-01

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

Bidirectional modulation of hippocampal gamma (20-80 Hz) frequency activity in vitro via alpha(α)- and beta(β)-adrenergic receptors (AR).

PubMed

Haggerty, D C; Glykos, V; Adams, N E; Lebeau, F E N

2013-12-03

Noradrenaline (NA) in the hippocampus plays an important role in memory function and has been shown to modulate different forms of synaptic plasticity. Oscillations in the gamma frequency (20-80 Hz) band in the hippocampus have also been proposed to play an important role in memory functions and, evidence from both in vitro and in vivo studies, has suggested this activity can be modulated by NA. However, the role of different NA receptor subtypes in the modulation of gamma frequency activity has not been fully elucidated. We have found that NA (30 μM) exerts a bidirectional control on the magnitude of kainate-evoked (50-200 nM) gamma frequency oscillations in the cornu Ammonis (CA3) region of the rat hippocampus in vitro via activation of different receptor subtypes. Activation of alpha-adrenergic receptors (α-AR) reduced the power of the gamma frequency oscillation. In contrast, activation of beta-adrenergic receptors (β-AR) caused an increase in the power of the gamma frequency oscillations. Using specific agonists and antagonists of AR receptor subtypes we demonstrated that these effects are mediated specifically via α1A-AR and β1-AR subtypes. NA activated both receptor subtypes, but the α1A-AR-mediated effect predominated, resulting in a reversible suppression of gamma frequency activity. These results suggest that NA is able to differentially modulate on-going gamma frequency oscillatory activity that could result in either increased or decreased information flow through the hippocampus. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

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.

Glutaraldehyde pretreatment blocks phospholipase A2 modulation of adrenergic receptors.

PubMed

Cohen, R M; McLellan, C; Dauphin, M; Hirata, F

1985-01-07

Treatment of rat cerebral cortical membranes with phospholipase A2 affects, in a parallel fashion, beta-, alpha 1- and alpha 2-adrenergic receptor binding, but not the affinity of these receptors for their respective ligands. Pretreatment of membranes with 0.1 percent glutaraldehyde blocks the effects of phospholipase A2 on adrenergic receptor binding. The results support the hypothesis that desensitization or "masking" of adrenergic receptors may involve changes in membrane lipid composition. Furthermore, glutaraldehyde may prove a useful tool in the investigation of the dynamic roles of lipids in receptor function and more specifically, their regulation and coupling to physiological events.

Adrenergic modulation of hepatotoxicity.

PubMed

Roberts, S M; DeMott, R P; James, R C

1997-01-01

Summaries of the interactions caused by altering adrenoreceptor activity in conjunction with the administration of selected hepatotoxicants are provided in Table 2 and Fig. 1. These hepatotoxicants can be divided into two groups, one whose toxicity is increased by adrenergic agonist drugs (group I) and the other whose toxicity is decreased by adrenergic antagonists (group II). Group I includes carbon tetrachloride, acetaminophen, and methylphenidate. Perhaps the most remarkable aspect these chemicals have in common is the striking potentiation that occurs with cotreatment with certain adrenergic agonist drugs. For each of these, cotreatment with the appropriate adrenergic agent can result in massive hepatocellular necrosis from an otherwise nontoxic dose. In terms of the specific adrenoreceptors involved and mechanisms of potentiation, however, they have little in common. Potentiation of carbon tetrachloride hepatotoxicity appears to be mediated by alpha(2)-adrenoceptor stimulation, acetaminophen is potentiated by alpha(1)-adrenoreceptor agonists, and methylphenidate responds to beta(2)-adrenoreceptor stimulation. Studies of the potentiation of carbon tetrachloride and acetaminophen agree that the timing of adrenergic stimulation relative to the hepatotoxicant dose is critically important to the interaction but markedly different for these two toxicants. Acetaminophen was potentiated only when the adrenergic drug was administered as a 3-h pretreatment. This is apparently a consequence of a mechanism of potentiation that involves adrenergic depression of hepatic glutathione content and a requirement that peak effects on glutathione of both the adrenergic agent and acetaminophen be coincident. The mechanism of potentiation of carbon tetrachloride hepatotoxicity is uncertain but clearly does not involve hepatic glutathione content. In contrast to acetaminophen, adrenergic effects must occur within a time window a few hours after the carbon tetrachloride dose for potentiation to occur. The importance of dose timing has not been evaluated for adrenergic potentiation of methylphenidate hepatotoxicity, but it is clear that this interaction is based on yet a third mechanism. While only three hepatotoxicants of the group I type have been examined in detail, the diversity of receptor types and mechanisms involved suggest that this phenomenon may be relevant for a wide variety of hepatotoxic drugs and chemicals. This interaction is also of interest because factors or events that lead to increased adrenergic stimulation are common in everyday life. Most over-the-counter cold and allergy preparations contain sympathomimetic drugs, and many prescription drugs produce adrenergic effects as either an extension of the intended therapeutic effect or as a side effect. Stress and some disease states can also lead to significant increases in peripheral adrenergic activity, creating the potential for increased susceptibility to hepatic injury from exposure to certain drugs or chemicals. Cocaine and bromobenzene represent group II, chemicals whose hepatotoxicity is diminished by cotreatment with adrenergic antagonist drugs. In the case of cocaine, adrenergic antagonist cotreatment was capable of reducing serum alanine aminotransferase activities by approximately 50%. For bromobenzene, the protection afforded by adrenergic antagonist cotreatment was more profound, with minimal hepatic lesions resulting from doses of bromobenzene that otherwise produced lethal hepatic necrosis. For the chemicals in group II, experimental observations are consistent with a phenomenon in which adrenergic potentiation of toxicity is supplied by the hepatotoxicant itself. Both cocaine and bromobenzene, in hepatotoxic doses increase endogenous catecholamine levels. When the effects of the elevated catecholamines are removed with the appropriate adrenergic antagonist, much lower toxicity (presumably due only to the direct hepatotoxic effects of the drug or chemical) is obse

Clonidine prevents enhancement of spinal sympathetic transmission by phosphodiesterase inhibitors.

PubMed

Franz, D N; Madsen, P W

1982-02-12

Preganglionic sympathetic discharges, evoked by cervical stimulation in spinal cats, were rapidly and markedly enhanced for 1-2 h by aminophylline or isobutylmethylxanthine. Clonidine depressed intraspinal transmission and prevented enhancement by the xanthines; alpha 2-receptor antagonists blocked the effect of clonidine and not only restored but also markedly prolonged the enhancement by the xanthines. The results suggest that the excitability of sympathetic preganglionic neurons is regulated by cyclic AMP through activation of different subtypes of adrenergic receptors that are either positively or negatively coupled to adenylate cyclase.

Receptor interactrions of imidazolines. VI. Significance of carbon bridge separating phenyl and imidazoline rings of tolazoline-like alpha adrenergic imidazolines.

PubMed

Ruffolo, R R; Yaden, E L; Waddell, J E; Dillard, R D

1980-09-01

The pharmacological significance of the carbon bridge separating the imidazoline and phenyl rings of tolazoline-like alpha adrenergic imidazolines has been investigated. Extending the carbon bridge to two carbon atoms, or deleting the carbon bridge, lowers affinity of the imidazolines for the alpha receptor and markedly decreases or abolishes efficacy (i.e., agonist activity), suggesting that a single carbon atome optimallyu separates the phenyl and imidazoline rings. Although one carbon is optimal for alpha adrenergic activity, this particular atom does not appear to be essential since nitrogen may substitute for carbon with no marked or consistent changes observed in affinity or efficacy. Hydroxylation of the carbon bridge decreases affinity for the receptor approximately 10-fold but does not alter efficacy, whereas a similar substitution made in the norepinephrine-series of phenethylamines markedly increases affinity (Patil et al., 1974). With both the imidazolines and phenethylamines, this carbon atom may stereoselectively influence binding to the receptor. These results suggest that the carbon atom bridging the phenyl and imidazoline rings of tolazoline-like imidazolines serves only to provide optimal separation between these rings and does not contribute directly to the binding process. It is proposed that alpha adrenergic imidazolines interact differently with the alpha adrenergic receptor than the norepinephrine-like phenethylamines.

Heterodimerization with beta2-adrenergic receptors promotes surface expression and functional activity of alpha1D-adrenergic receptors.

PubMed

Uberti, Michelle A; Hague, Chris; Oller, Heide; Minneman, Kenneth P; Hall, Randy A

2005-04-01

The alpha1D-adrenergic receptor (alpha1D-AR) is a G protein-coupled receptor (GPCR) that is poorly trafficked to the cell surface and largely nonfunctional when heterologously expressed by itself in a variety of cell types. We screened a library of approximately 30 other group I GPCRs in a quantitative luminometer assay for the ability to promote alpha1D-AR cell surface expression. Strikingly, these screens revealed only two receptors capable of inducing robust increases in the amount of alpha1D-AR at the cell surface: alpha1B-AR and beta2-AR. Confocal imaging confirmed that coexpression with beta2-AR resulted in translocation of alpha1D-AR from intracellular sites to the plasma membrane. Additionally, coimmunoprecipitation studies demonstrated that alpha1D-AR and beta2-AR specifically interact to form heterodimers when coexpressed in HEK-293 cells. Ligand binding studies revealed an increase in total alpha1D-AR binding sites upon coexpression with beta2-AR, but no apparent effect on the pharmacological properties of the receptors. In functional studies, coexpression with beta2-AR significantly enhanced the coupling of alpha1D-AR to norepinephrine-stimulated Ca2+ mobilization. Heterodimerization of beta2-AR with alpha1D-AR also conferred the ability of alpha1D-AR to cointernalize upon beta2-AR agonist stimulation, revealing a novel mechanism by which these different adrenergic receptor subtypes may regulate each other's activity. These findings demonstrate that the selective association of alpha1D-AR with other receptors is crucial for receptor surface expression and function and also shed light on a novel mechanism of cross talk between alpha1- and beta2-ARs that is mediated through heterodimerization and cross-internalization.

Reconstitution of high affinity. cap alpha. /sub 2/ adrenergic agonist binding by fusion with a pertussis toxin substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, M.H.; Neubig, R.R.

1986-03-05

High affinity ..cap alpha../sub 2/ adrenergic agonist binding is thought to occur via a coupling of the ..cap alpha../sub 2/ receptor with N/sub i/, the inhibitory guanyl nucleotide binding protein. Human platelet membranes pretreated at pH 11.5 exhibit a selective inactivation of agonist binding and N/sub i/. To further study the mechanism of agonist binding, alkali treated membranes (ATM) were mixed with membranes pretreated with 10 ..mu..M phenoxybenzamine to block ..cap alpha../sub 2/ receptors (POB-M). The combined membrane pellet was incubated in 50% polyethylene glycol (PEG) to promote membrane-membrane fusion and assayed for binding to the ..cap alpha../sub 2/ agonistmore » (/sup 3/H)UK 14,304 (UK) and the antagonist (/sup 3/H) yohimbine. PEG treatment resulted in a 2-4 fold enhancement of UK binding whereas yohimbine binding was unchanged. No enhancement of UK binding was observed in the absence of PEG treatment. The reconstitution was dependent on the addition of POB-M. They found that a 1:1 ratio of POB-M:ATM was optimal. Reconstituted binding was inhibited by GppNHp. Fusion of rat C6 glioma cell membranes, which do not contain ..cap alpha../sub 2/ receptors, also enhanced agonist binding to ATM. Fusion of C6 membranes from cells treated with pertussis toxin did not enhance (/sup 3/H) UK binding. These data show that a pertussis toxin sensitive membrane component, possibly N/sub i/, can reconstitute high affinity ..cap alpha../sub 2/ agonist binding.« less

Immunocytochemical localization of muscarinic, adrenergic and AT1 receptors.

PubMed

Schulze, W; Fu, M L

1996-01-01

By indirect immunofluorescence and post-embedding EM gold technique, the localization of alpha 1-adrenergic, M2-muscarinic and angiotensin II receptor-I (AT1) were determinated. With antipeptide antibodies directed against the second extracellular loops of all three receptors, these receptors were found to be localized at the sarcolemma of adult rat cardiomyocytes and at the surface membranes of cultivated neonatal heart cells. Additionally, M2 receptors were localized along T-tubule membranes of both rat and human adult cardiomyocytes. alpha 1-Adrenergic receptors were found intracellular near the surface of atrial granules (ANF-granules). By using M2 and alpha 1-adrenergic receptor antibodies the strongest fluorescence was found in the right atrium of the rat. Besides the localization in cardiomyocytes, AT1 receptors were also localized in outer plasma membranes and the endoplasmic reticulum of fibroblasts, and the surface of smooth muscle cells of the major arteries and veins. Likewise, the muscarinic M2 receptors were found along the outer membranes of endothelial cells from capillaries and endocardium.

Tolazoline reversal of xylazine in bison (Bison bison): Mitigation of adverse effects

USGS Publications Warehouse

Roffe, Thomas J.; Sweeney, Steven J.; Williams, Beth; Quist, Charlotte

2002-01-01

Tolazoline is a mixed alpha-1 and -2 adrenergic antagonist used to reverse the sedative, analgesic and muscle-relaxing effects of xylazine, a potent alpha adrenergic agonist. Tolazoline has been used in cattle and is superior to yohimbine, another alpha adrenergic antagonist, in this species. In white-tailed deer, tolazoline shortened recovery times and reversed xylazine-induced bradycardia, respiratory depression, and bloat following xylazine-ketamine anesthesia (Kreeger et al. 1986). We have used it for a number of years in moose without any detected adverse reactions. Caulkett et al. (2000) used tolazoline in wood bison to reverse the xylazine-induced effects of xylazine-tiletamine/zolazepam anesthesia and did not report any ill effects. However, the reported side effects of tolazoline in horses (species for which the drug was developed and is labeled) include abdominal discomfort, gastrointestinal hypermotility, diarrhea, tachycardia, ventricular dysrhythmia, hypertension and apprehensiveness.

Synthesis and pharmacological characterization of beta2-adrenergic agonist enantiomers: zilpaterol.

PubMed

Kern, Christopher; Meyer, Thorsten; Droux, Serge; Schollmeyer, Dieter; Miculka, Christian

2009-03-26

The beta-adrenergic agonist 1 (zilpaterol) is used as production enhancer in cattle. Binding experiments of separated enantiomers on recombinant human beta(2)-adrenergic and mu-opioid receptors and functional studies showed that the (-)-1 enantiomer accounts for essentially all the beta(2)-adrenergic agonist activity and that it exhibits less affinity toward the mu-opioid receptor than (+)-1, which is a mu-opioid receptor antagonist. X-ray crystallography revealed the absolute configuration of (-)-1 to be 6R,7R.

Modulation of intracellular Ca2+ via L-type calcium channels in heart cells by the autoantibody directed against the second extracellular loop of the alpha1-adrenoceptors.

PubMed

Bkaily, Ghassan; El-Bizri, Nesrine; Bui, Michel; Sukarieh, Rami; Jacques, Danielle; Fu, Michael L X

2003-03-01

The effects of methoxamine, a selective alpha1-adrenergic receptor agonist, and the autoantibody directed against the second extracellular loop of alpha1-adrenoceptors were studied on intracellular free Ca2+ levels using confocal microscopy and ionic currents using the whole-cell patch clamp technique in single cells of 10-day-old embryonic chick and 20-week-old fetal human hearts. We observed that like methoxamine, the autoantibody directed against the second extracellular loop of alpha1-adrenoreceptors significantly increased the L-type calcium current (I(Ca(L))) but had no effect on the T-type calcium current (I(Ca(T))), the delayed outward potassium current, or the fast sodium current. This effect of the autoantibody was prevented by a prestimulation of the receptors with methoxamine and vice versa. Moreover, treating the cells with prazosin, a selective alpha1-adrenergic receptor antagonist blocked the methoxamine and the autoantibody-induced increase in I(Ca(L)), respectively. In absence of prazosin, both methoxamine and the autoantibody showed a substantial enhancement in the frequency of cell contraction and that of the concomitant cytosolic and nuclear free Ca2+ variations. The subsequent addition of nifedipine, a specific L-type Ca2+ channel blocker, reversed not only the methoxamine or the autoantibody-induced effect but also completely abolished cell contraction. These results demonstrated that functional alpha1-adrenoceptors exist in both 10-day-old embryonic chick and 20-week-old human fetal hearts and that the autoantibody directed against the second extracellular loop of this type of receptors plays an important role in stimulating their activity via activation of L-type calcium channels. This loop seems to have a functional significance by being the target of alpha1-receptor agonists like methoxamine.

Design and synthesis of aryloxypropanolamine as β3-adrenergic receptor antagonist in cancer and lipolysis.

PubMed

Jin, Jiyu; Miao, Chunxiao; Wang, Zhilong; Zhang, Wanli; Zhang, Xiongwen; Xie, Xin; Lu, Wei

2018-04-25

β-adrenergic receptors (β-ARs) are broadly distributed in various tissues and regulate a panel of important physiological functions and disease states including cancer. Above all, β 3 -adrenergic receptor (β 3 -AR) plays a significant role in regulating lipolysis and thermogenesis in adipose tissue. In this study, we designed and synthesized a series of novel L-748,337 derivatives as selective human β 3 -AR antagonists. Among all the tested L-748,337 analogs, compound 23d was found to display 23-fold more potent β 3 -AR antagonist activity (EC 50  = 0.5117 nM) than L-748,337 (EC 50  = 11.91 nM). In vivo, compound 23d could alleviate weight loss and inhibit tumor growth in C26 tumor cachexia animal model. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Involvement of histaminergic and noradrenergic receptors in the oxytocin-induced food intake in neonatal meat-type chicks.

PubMed

Mirnaghizadeh, Seyed Vahid; Zendehdel, Morteza; Babapour, Vahab

2017-03-01

Oxytocin neurons have a physiological role in food intake and energy balance. Several studies have shown that central histaminergic and adrenergic systems synapse on oxytocin neurons but there is no information for their interaction on food intake regulation in birds. The purpose of this study was to examine the effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H1 receptors antagonist), famotidine (histamine H2 receptors antagonist), thioperamide (histamine H3 receptors antagonist), prazosin (α1 receptor antagonist), yohimbine (α2 receptor antagonist), metoprolol (β1 adrenergic receptor antagonist), ICI 118,551 (β2 adrenergic receptor antagonist) and SR59230R (β3 adrenergic receptor antagonist) on oxytocin-induced hypophagia in 3-h food-deprived (FD 3 ) neonatal broiler chicken. In Experiment 1, 3 h-fasted chicks were given an ICV injection of saline, α-FMH (250 nmol), oxytocin (10 μg) and co-injection of α-FMH + oxytocin. Experiments 2-9 were similar to experiment 1 except birds were injected with chlorpheniramine (300 nmol), famotidine (82 nmol), thioperamide (300 nmol), prazosin (10 nmol), yohimbine (13 nmol), metoprolol (24 nmol), ICI 118,551(5 nmol) and SR59230R (20 nmol) instead of α-FMH, respectively. After injection cumulative food intake was measured until 120 min post injection. According to the results, ICV injection of oxytocin significantly decreased food intake in broiler chickens (P < 0.001). ICV injection of α-FMH significantly attenuated hypophagic effect of oxytocin (P < 0.001). Also, co-injection of chlorpheniramine plus oxytocin significantly decreased the effect of oxytocin on food intake (P < 0.001). Co-administration of thioperamide and oxytocin significantly amplified hypophagic effect of oxytocin in chickens (P < 0.001). In addition, ICI 118,551 attenuated hypophagic effect of oxytocin (P < 0.001); while famotidine, prazosin, yohimbine, metoprolol and SR59230R had no effect on oxytocin- induced food intake in FD3 broiler chickens. These results suggest that the effect of oxytocin on food intake is probably mediated by histaminergic (via H1 and H3 receptors) and noradrenergic (via β2 receptors) systems in broiler chickens.

Orexin A-induced anxiety-like behavior is mediated through GABA-ergic, α- and β-adrenergic neurotransmissions in mice.

PubMed

Palotai, Miklós; Telegdy, Gyula; Jászberényi, Miklós

2014-07-01

Orexins are hypothalamic neuropeptides, which are involved in several physiological functions of the central nervous system, including anxiety and stress. Several studies provide biochemical and behavioral evidence about the anxiogenic action of orexin A. However, we have little evidence about the underlying neuromodulation. Therefore, the aim of the present study was to investigate the involvement of neurotransmitters in the orexin A-induced anxiety-like behavior in elevated plus maze (EPM) test in mice. Accordingly, mice were pretreated with a non-selective muscarinic cholinergic antagonist, atropine; a γ-aminobutyric acid subunit A (GABA-A) receptor antagonist, bicuculline; a D2, D3, D4 dopamine receptor antagonist, haloperidol; a non-specific nitric oxide synthase (NOS) inhibitor, nitro-l-arginine; a nonselective α-adrenergic receptor antagonist, phenoxybenzamine and a β-adrenergic receptor antagonist, propranolol 30min prior to the intracerebroventricular administration of orexin A. The EPM test started 30min after the i.c.v. injection of the neuropeptide. Our results show that orexin A decreases significantly the time spent in the arms (open/open+closed) and this action is reversed by bicuculline, phenoxybenzamine and propranolol, but not by atropine, haloperidol or nitro-l-arginine. Our results provide evidence for the first time that the orexin A-induced anxiety-like behavior is mediated through GABA-A-ergic, α- and β-adrenergic neurotransmissions, whereas muscarinic cholinergic, dopaminergic and nitrergic neurotransmissions may not be implicated. Copyright © 2014 Elsevier Inc. All rights reserved.

Muscarinic and alpha 1-adrenergic receptor binding characteristics of saw palmetto extract in rat lower urinary tract.

PubMed

Suzuki, Mayumi; Oki, Tomomi; Sugiyama, Tomomi; Umegaki, Keizo; Uchida, Shinya; Yamada, Shizuo

2007-06-01

To elucidate the in vitro and ex vivo effects of saw palmetto extract (SPE) on autonomic receptors in the rat lower urinary tract. The in vitro binding affinities for alpha 1-adrenergic, muscarinic, and purinergic receptors in the rat prostate and bladder were measured by radioligand binding assays. Rats received vehicle or SPE (0.6 to 60 mg/kg/day) orally for 4 weeks, and alpha 1-adrenergic and muscarinic receptor binding in tissues of these rats were measured. Saw palmetto extract inhibited specific binding of [3H]prazosin and [N-methyl-3H]scopolamine methyl chloride (NMS) but not alpha, beta-methylene adenosine triphosphate [2,8-(3)H]tetrasodium salt in the rat prostate and bladder. The binding activity of SPE for muscarinic receptors was four times greater than that for alpha 1-adrenergic receptors. Scatchard analysis revealed that SPE significantly reduced the maximal number of binding sites (Bmax) for each radioligand in the prostate and bladder under in vitro condition. Repeated oral administration of SPE to rats brought about significant alteration in Bmax for prostatic [3H]prazosin binding and for bladder [3H]NMS binding. Such alteration by SPE was selective to the receptors in the lower urinary tract. Saw palmetto extract exerts significant binding activity on autonomic receptors in the lower urinary tract under in vitro and in vivo conditions.

Adrenergic Agonists Bind to Adrenergic-Receptor-Like Regions of the Mu Opioid Receptor, Enhancing Morphine and Methionine-Enkephalin Binding: A New Approach to "Biased Opioids"?

PubMed

Root-Bernstein, Robert; Turke, Miah; Subhramanyam, Udaya K Tiruttani; Churchill, Beth; Labahn, Joerg

2018-01-17

Extensive evidence demonstrates functional interactions between the adrenergic and opioid systems in a diversity of tissues and organs. While some effects are due to receptor and second messenger cross-talk, recent research has revealed an extracellular, allosteric opioid binding site on adrenergic receptors that enhances adrenergic activity and its duration. The present research addresses whether opioid receptors may have an equivalent extracellular, allosteric adrenergic binding site that has similar enhancing effects on opioid binding. Comparison of adrenergic and opioid receptor sequences revealed that these receptors share very significant regions of similarity, particularly in some of the extracellular and transmembrane regions associated with adrenergic binding in the adrenergic receptors. Five of these shared regions from the mu opioid receptor (muOPR) were synthesized as peptides and tested for binding to adrenergic, opioid and control compounds using ultraviolet spectroscopy. Adrenergic compounds bound to several of these muOPR peptides with low micromolar affinity while acetylcholine, histamine and various adrenergic antagonists did not. Similar studies were then conducted with purified, intact muOPR with similar results. Combinations of epinephrine with methionine enkephalin or morphine increased the binding of both by about half a log unit. These results suggest that muOPR may be allosterically enhanced by adrenergic agonists.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scherer, R.W.

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); eithermore » 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.« less

Computer-assisted determination of minimum energy conformations. 7: A pharmacophore model of the active region of the alpha2-adrenoceptor

NASA Astrophysics Data System (ADS)

Ashman, William P.; Mickiewicz, A. P.; Nelson, Todd M.

1992-09-01

Molecular modeling and computational chemistry techniques are used to analyze compounds in developing pharmacophores of biological receptors to use as templates in structure activity relationship studies and to design new chemicals having physiological activity of interest. In this study, the results of x-ray crystal analyses and PM3 semi-empirical molecular orbital conformational analyses are used to determine the three-dimensional representations of selected adrenergic compounds known to be agonists with the alpha2-adrenoceptor in achieving optimized geometries and electrostatic parameters. The alpha2-adrenergic agonists interact with the adrenergic system receptors to produce various increases or decreases in hemodynamic responses (i.e., hypertension, hypotension, and bradycardia) and sedation. A pharmacophore model of the active region of the alpha2-adrenoceptor is described based on the superimposition of common structural, electrostatic, and physicochemical features of the compounds. Using the model to predict compound adrenergic activity and to design alpha2-adrenergic compounds is discussed.

Macromolecular beta-adrenergic antagonists discriminating between receptor and antibody.

PubMed Central

Pitha, J; Zjawiony, J; Lefkowitz, R J; Caron, M G

1980-01-01

The beta-adrenergic antagonist, alprenolol, was attached in an irreversible manner to macromolecular dextran via side arms that differed in length. The ability of these macromolecules to bind to the beta-adrenergic receptor of frog erythrocytes and to catecholamine-binding antibodies raised against partially purified receptors was studied. Compared to the parent drug the potency of binding of macromolecular alprenolol to the receptor decreased about 1/10, 1/600, and 1/8000 when the length of the arm separating alprenolol from the dextran moiety was 13, 8, and 4 atoms, respectively. In contrast, the binding potencies of the parent drug and of all its macromolecular derivatives for the antibody were within the same order of magnitude. Thus, conversion of a drug to a macromolecular form may not only sustain its binding activity but may also lead in a higher selectivity. The macromolecular derivatives described here may be suitable probes for investigation of the location and of the molecular properties of the binding sites for beta-adrenergic drugs. PMID:6154947

Mechanisms of alpha 1-adrenergic vascular desensitization in conscious dogs

NASA Technical Reports Server (NTRS)

Kiuchi, K.; Vatner, D. E.; Uemura, N.; Bigaud, M.; Hasebe, N.; Hempel, D. M.; Graham, R. M.; Vatner, S. F.

1992-01-01

To investigate the mechanisms of alpha 1-adrenergic vascular desensitization, osmotic minipumps containing either saline (n = 9) or amidephrine mesylate (AMD) (n = 9), a selective alpha 1-adrenergic receptor agonist, were implanted subcutaneously in dogs with chronically implanted arterial and right atrial pressure catheters and aortic flow probes. After chronic alpha 1-adrenergic receptor stimulation, significant physiological desensitization to acute AMD challenges was observed, i.e., pressor and vasoconstrictor responses to the alpha 1-adrenergic agonist were significantly depressed (p < 0.01) compared with responses in the same dogs studied in the conscious state before pump implantation. However, physiological desensitization to acute challenges of the neurotransmitter norepinephrine (NE) (0.1 micrograms/kg per minute) in the presence of beta-adrenergic receptor blockade was not observed for either mean arterial pressure (MAP) (30 +/- 7 versus 28 +/- 5 mm Hg) or total peripheral resistance (TPR) (29.8 +/- 4.9 versus 28.9 +/- 7.3 mm Hg/l per minute). In the presence of beta-adrenergic receptor plus ganglionic blockade after AMD pump implantation, physiological desensitization to NE was unmasked since the control responses to NE (0.1 micrograms/kg per minute) before the AMD pumps were now greater (p < 0.01) than after chronic AMD administration for both MAP (66 +/- 5 versus 32 +/- 2 mm Hg) and TPR (42.6 +/- 10.3 versus 23.9 +/- 4.4 mm Hg/l per minute). In the presence of beta-adrenergic receptor, ganglionic, plus NE-uptake blockade after AMD pump implantation, desensitization was even more apparent, since NE (0.1 micrograms/kg per minute) induced even greater differences in MAP (33 +/- 5 versus 109 +/- 6 mm Hg) and TPR (28.1 +/- 1.8 versus 111.8 +/- 14.7 mm Hg/l per minute). The maximal force of contraction induced by NE in the presence or absence of endothelium was significantly decreased (p < 0.05) in vitro in mesenteric artery rings from AMD pump dogs compared with saline control dogs. Furthermore, alpha 1-adrenergic receptor density, as determined by [3H]prazosin binding in membrane preparations from vessels in the mesentery, was decreased (8.2 +/- 1.0 versus 18.4 +/- 1.4 fmol/mg protein, p < 0.001) without any change in Kd in the AMD pump dogs compared with the saline pump dogs.(ABSTRACT TRUNCATED AT 400 WORDS).

Suppressive Effects of Bee Venom Acupuncture on Paclitaxel-Induced Neuropathic Pain in Rats: Mediation by Spinal α2-Adrenergic Receptor

PubMed Central

Choi, Jiho; Jeon, Changhoon; Jang, Jo Ung; Quan, Fu Shi; Lee, Kyungjin; Kim, Woojin

2017-01-01

Paclitaxel, a chemotherapy drug for solid tumors, induces peripheral painful neuropathy. Bee venom acupuncture (BVA) has been reported to have potent analgesic effects, which are known to be mediated by activation of spinal α-adrenergic receptor. Here, we investigated the effect of BVA on mechanical hyperalgesia and spinal neuronal hyperexcitation induced by paclitaxel. The role of spinal α-adrenergic receptor subtypes in the analgesic effect of BVA was also observed. Administration of paclitaxel (total 8 mg/kg, intraperitoneal) on four alternate days (days 0, 2, 4, and 6) induced significant mechanical hyperalgesic signs, measured using a von Frey filament. BVA (1 mg/kg, ST36) relieved this mechanical hyperalgesia for at least two hours, and suppressed the hyperexcitation in spinal wide dynamic range neurons evoked by press or pinch stimulation. Both melittin (0.5 mg/kg, ST36) and phospholipase A2 (0.12 mg/kg, ST36) were shown to play an important part in this analgesic effect of the BVA, as they significantly attenuated the pain. Intrathecal pretreatment with the α2-adrenergic receptor antagonist (idazoxan, 50 µg), but not α1-adrenergic receptor antagonist (prazosin, 30 µg), blocked the analgesic effect of BVA. These results suggest that BVA has potent suppressive effects against paclitaxel-induced neuropathic pain, which were mediated by spinal α2-adrenergic receptor. PMID:29088102

Norepinephrine signaling through β-adrenergic receptors is critical for expression of cocaine-induced anxiety

PubMed Central

Schank, Jesse R.; Liles, L. Cameron; Weinshenker, David

2008-01-01

Background Cocaine is a widely abused psychostimulant that has both rewarding and aversive properties. While the mechanisms underlying cocaine’s rewarding effects have been studied extensively, less attention has been paid to the unpleasant behavioral states induced by cocaine, such as anxiety. Methods In this study we evaluated the performance of dopamine β-hydroxylase knockout (Dbh −/−) mice, which lack norepinephrine (NE), in the elevated plus maze (EPM) to examine the contribution of noradrenergic signaling to cocaine-induced anxiety. Results We found that cocaine dose-dependently increased anxiety-like behavior in control (Dbh +/−) mice, as measured by a decrease in open arm exploration. Dbh −/− mice had normal baseline performance in the EPM, but were completely resistant to the anxiogenic effects of cocaine. Cocaine-induced anxiety was also attenuated in Dbh +/− mice following administration of disulfiram, a DBH inhibitor. In experiments using specific adrenergic antagonists, we found that pretreatment with the β-adrenergic receptor antagonist propranolol blocked cocaine-induced anxiety-like behavior in Dbh +/− and wild-type C57BL6/J mice, while the α1 antagonist prazosin and the α2 antagonist yohimbine had no effect. Conclusions These results indicate that noradrenergic signaling via β-adrenergic receptors is required for cocaine-induced anxiety in mice. PMID:18083142

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadel, G.L.; Malik, K.U.; Lew, D.B.

The purpose of this study was to examine arachidonic acid (AA) metabolism and to characterize the type of adrenergic receptor (AR) involved in the production of the major metabolite of this fatty acid. ({sup 14}C)AA was incubated with GPT-rings and the radiolabelled products were extracted and separated by TLC method. The medium was also assayed for radiolabelled immunoreactive PG's (iPG's) and leukotrienes (LT) B4 and C4 by RIA or Enzyme immunoassay (EIA) after exposure to various AR agonists. ({sup 14}C)AA was incorporated into GPT-rings and metabolized mainly into iPGE2 and smaller amounts into PGF2{alpha}. Trace amounts of PGD2 and 6-keto-PGF1{alpha}more » but not LTB4 or LTC4 were detected by RIA and/or EIA. Incubation of GPT rings for 15 minutes with isoproterenol and salbutamol resulted in a significant increase of PGE2 synthesis (optimum conc: 10{sup {minus}7}, 10{sup {minus}7}M respectively). In contrast, dobutamine, norepinephrine, phenylnephrine and xylazine (up to 10{sup {minus}6}M) did not significantly increase PGE2 production. Isoproterenol-induced iPGE2 production was inhibited by a selective {beta}2 antagonist, butoxamine (70%: 10{sup {minus}7}M, 91%: 10{sup {minus}6}M) and somewhat reduced by {beta}1 antagonists practolol and metoprolol (30-64%:10{sup {minus}6}M). These data suggest that isoproterenol induced iPGE2 synthesis is primarily mediated via activation of {beta}2 adrenergic receptor.« less

3-Isobutyl-1-methylxanthine increases alpha-1-adrenergic receptor sensitivity and density in DDT1-MF2 smooth muscle cells.

PubMed

Schachter, J B; Wolfe, B B

1995-01-01

The effect of chronic exposure of DDT1-MF2 smooth muscle cells to the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) was investigated with regard to the dynamics of alpha-1-adrenergic receptors. After 48 hr of exposure to 750 microM IBMX, the magnitude of the maximal phospholipase C response to norepinephrine was increased approximately 2-fold and the potency of norepinephrine was increased almost 3-fold. Similar effects were noted for the response to ATP. The density of alpha-1-adrenergic receptors, as defined by [3H]-prazosin binding to membranes was increased 2-fold. In addition, chronic treatment with IBMX prevented agonist-induced desensitization of alpha-1-adrenergic receptors and enhanced the rate of receptor resensitization subsequent to desensitization by a combination of agonist and phorbol ester. These effects appear to be regulated by a cyclic AMP-dependent mechanism. Thus, chronic exposure of smooth muscle cells to phosphodiesterase inhibition may activate compensatory mechanisms that lead to enhanced sensitivity to contractile stimuli. The potential importance of such compensatory mechanisms in the treatment and etiology of smooth muscle dysfunction is briefly discussed.

Adrenergic Agonists Bind to Adrenergic-Receptor-Like Regions of the Mu Opioid Receptor, Enhancing Morphine and Methionine-Enkephalin Binding: A New Approach to “Biased Opioids”?

PubMed Central

Turke, Miah; Subhramanyam, Udaya K. Tiruttani; Churchill, Beth; Labahn, Joerg

2018-01-01

Extensive evidence demonstrates functional interactions between the adrenergic and opioid systems in a diversity of tissues and organs. While some effects are due to receptor and second messenger cross-talk, recent research has revealed an extracellular, allosteric opioid binding site on adrenergic receptors that enhances adrenergic activity and its duration. The present research addresses whether opioid receptors may have an equivalent extracellular, allosteric adrenergic binding site that has similar enhancing effects on opioid binding. Comparison of adrenergic and opioid receptor sequences revealed that these receptors share very significant regions of similarity, particularly in some of the extracellular and transmembrane regions associated with adrenergic binding in the adrenergic receptors. Five of these shared regions from the mu opioid receptor (muOPR) were synthesized as peptides and tested for binding to adrenergic, opioid and control compounds using ultraviolet spectroscopy. Adrenergic compounds bound to several of these muOPR peptides with low micromolar affinity while acetylcholine, histamine and various adrenergic antagonists did not. Similar studies were then conducted with purified, intact muOPR with similar results. Combinations of epinephrine with methionine enkephalin or morphine increased the binding of both by about half a log unit. These results suggest that muOPR may be allosterically enhanced by adrenergic agonists. PMID:29342106

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

PubMed

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.

Effects of three antagonists on selected pharmacodynamic effects of sublingually administered detomidine in the horse.

PubMed

Knych, Heather K; Stanley, Scott D

2014-01-01

To describe the effects of alpha2 -adrenergic receptor antagonists on the pharmacodynamics of sublingual (SL) detomidine in the horse. Randomized crossover design. Nine healthy adult horses with an average age of 7.6 ± 6.5 years. Four treatment groups were studied: 1) 0.04 mg kg(-1) detomidine SL; 2) 0.04 mg kg(-1) detomidine SL followed 1 hour later by 0.075 mg kg(-1) yohimbine intravenously (IV); 3) 0.04 mg kg(-1) detomidine SL followed 1 hour later by 4 mg kg(-1) tolazoline IV; and 4) 0.04 mg kg(-1) detomidine SL followed 1 hour later by 0.12 mg kg(-1) atipamezole IV. Each horse received all treatments with a minimum of 1 week between treatments. Blood samples were obtained and plasma analyzed for yohimbine, atipamezole and tolazoline concentrations by liquid chromatography-mass spectrometry. Behavioral effects, heart rate and rhythm, glucose, packed cell volume (PCV) and plasma proteins were monitored. Chin-to-ground distance increased following administration of the antagonists, however, this effect was transient, with a return to pre-reversal values as early as 1 hour. Detomidine induced bradycardia and increased incidence of atrioventricular blocks were either transiently or incompletely antagonized by all antagonists. PCV and glucose concentrations increased with tolazoline administration, and atipamezole subjectively increased urination frequency but not volume. At the doses administered in this study, the alpha2 -adrenergic antagonistic effects of tolazoline, yohimbine and atipamezole on cardiac and behavioral effects elicited by SL administration of detomidine are transient and incomplete. © 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Serotonin-induced hypophagia is mediated via α2 and β2 adrenergic receptors in neonatal layer-type chickens.

PubMed

Zendehdel, M; Sardari, F; Hassanpour, S; Rahnema, M; Adeli, A; Ghashghayi, E

2017-06-01

1. Serotoninergic and adrenergic systems play crucial roles in feed intake regulation in avians but there is no report on possible interactions among them. So, in this study, 5 experiments were designed to evaluate the interaction of central serotonergic and adrenergic systems on food intake regulation in 3 h food deprived (FD 3 ) neonatal layer-type chickens. 2. In Experiment 1, chickens received intracerebroventricular (ICV) injection of control solution, serotonin (56.74 nmol), prazosin (α 1 receptor antagonist, 10 nmol) and co-injection of serotonin plus prazosin. In Experiment 2, control solution, serotonin (56.74 nmol), yohimbine (α 2 receptor antagonist, 13 nmol) and co-injection of serotonin plus yohimbine were used. In Experiment 3, the birds received control solution, serotonin (56.74 nmol), metoprolol (β 1 receptor antagonist, 24 nmol) and co-injection of serotonin plus metoprolol. In Experiment 4, injections were control solution, serotonin (56.74 nmol), ICI 118.551 (β 2 receptor antagonist, 5 nmol) and serotonin plus ICI 118.551. In Experiment 5, control solution, serotonin (56.74 nmol), SR59230R (β 3 receptor antagonist, 20 nmol) and co-administration of serotonin and SR59230R were injected. In all experiments the cumulative food intake was measured until 120 min post injection. 3. The results showed that ICV injection of serotonin alone decreased food intake in chickens. A combined injection of serotonin plus ICI 118.551 significantly attenuated serotonin-induced hypophagia. Also, co-administration of serotonin and yohimbine significantly amplified the hypophagic effect of serotonin. However, prazosin, metoprolol and SR59230R had no effect on serotonin-induced hypophagia in chickens. 4. These results suggest that serotonin-induced feeding behaviour is probably mediated via α 2 and β 2 adrenergic receptors in neonatal layer-type chicken.

[The effects of epinephrine and adrenergic antagonists on adenosine 3', 5'-monophosphate level of bovine trabecular cells in vitro].

PubMed

Lu, Y; Li, M; Shen, Y

1998-03-01

To determine the effects of epinephrine (EPI) and adrenergic antagonists on adenosine 3', 5'-monophosphate (cAMP) level of bovine trabecular cells (BTC) in vitro. (3)H-cAMP was used in protein binding assay for measuring the intracellular level of cAMP. (1) 10(-5) mol/L EPI induced a fold increase of cAMP in cultured BTC in vitro; (2) Timilol and ICI 118, 551 blocked efficiently the effect of EPI at a lower concentration (10(-6) mol/L). (3) Bisoprolol did not efficiently block the effect of EPI unless at high concentrations (>or= 10(-5) mol/L). The effects of EPI increasing outflow facility may be associated with its increase of cAMP in trabecular cells; BTC contains beta-adrenergic receptors, and beta(2)-adrenergic receptors are dominant.

Adrenergic signaling mediates mechanical hyperalgesia through activation of P2X3 receptors in primary sensory neurons of rats with chronic pancreatitis.

PubMed

Wang, Shusheng; Zhu, Hong-Yan; Jin, Yi; Zhou, Youlang; Hu, Shufen; Liu, Tong; Jiang, Xinghong; Xu, Guang-Yin

2015-04-15

The mechanism of pain in chronic pancreatitis (CP) is poorly understood. The aim of this study was designed to investigate roles of norepinephrine (NE) and P2X receptor (P2XR) signaling pathway in the pathogenesis of hyperalgesia in a rat model of CP. CP was induced in male adult rats by intraductal injection of trinitrobenzene sulfonic acid (TNBS). Mechanical hyperalgesia was assessed by referred somatic behaviors to mechanical stimulation of rat abdomen. P2XR-mediated responses of pancreatic dorsal root ganglion (DRG) neurons were measured utilizing calcium imaging and whole cell patch-clamp-recording techniques. Western blot analysis and immunofluorescence were performed to examine protein expression. TNBS injection produced a significant upregulation of P2X3R expression and an increase in ATP-evoked responses of pancreatic DRG neurons. The sensitization of P2X3Rs was reversed by administration of β-adrenergic receptor antagonist propranolol. Incubation of DRG neurons with NE significantly enhanced ATP-induced intracellular calcium signals, which were abolished by propranolol, and partially blocked by protein kinase A inhibitor H-89. Interestingly, TNBS injection led to a significant elevation of NE concentration in DRGs and the pancreas, an upregulation of β2-adrenergic receptor expression in DRGs, and amplification of the NE-induced potentiation of ATP responses. Importantly, pancreatic hyperalgesia was markedly attenuated by administration of purinergic receptor antagonist suramin or A317491 or β2-adrenergic receptor antagonist butoxamine. Sensitization of P2X3Rs, which was likely mediated by adrenergic signaling in primary sensory neurons, contributes to pancreatic pain, thus identifying a potential target for treating pancreatic pain caused by inflammation. Copyright © 2015 the American Physiological Society.

Identification of the functional domain in the transcription factor RTEF-1 that mediates alpha 1-adrenergic signaling in hypertrophied cardiac myocytes.

PubMed

Ueyama, T; Zhu, C; Valenzuela, Y M; Suzow, J G; Stewart, A F

2000-06-09

Cardiac myocytes respond to alpha(1)-adrenergic receptor stimulation by a progressive hypertrophy accompanied by the activation of many fetal genes, including skeletal muscle alpha-actin. The skeletal muscle alpha-actin gene is activated by signaling through an MCAT element, the binding site of the transcription enhancer factor-1 (TEF-1) family of transcription factors. Previously, we showed that overexpression of the TEF-1-related factor (RTEF-1) increased the alpha(1)-adrenergic response of the skeletal muscle alpha-actin promoter, whereas TEF-1 overexpression did not. Here, we identified the functional domains and specific sequences in RTEF-1 that mediate the alpha(1)-adrenergic response. Chimeric TEF-1 and RTEF-1 expression constructs localized the region responsible for the alpha(1)-adrenergic response to the carboxyl-terminal domain of RTEF-1. Site-directed mutagenesis was used to inactivate eight serine residues of RTEF-1, not present in TEF-1, that are putative targets of alpha(1)-adrenergic-dependent kinases. Mutation of a single serine residue, Ser-322, reduced the alpha(1)-adrenergic activation of RTEF-1 by 70% without affecting protein stability, suggesting that phosphorylation at this serine residue accounts for most of the alpha(1)-adrenergic response. Thus, these results demonstrate that RTEF-1 is a direct target of alpha(1)-adrenergic signaling in hypertrophied cardiac myocytes.

Effects of Adrenergic Blockade on Postpartum Adaptive Responses Induced by Labor Contractions

NASA Technical Reports Server (NTRS)

Ronca, April E.; Mills, N. A.; Lam, K. P.; Hayes, L. E.; Bowley, Susan M. (Technical Monitor)

2000-01-01

Prenatal exposure to labor contractions augments the expression of postnatal adaptive responses in newborn rats. Near-term rat fetuses exposed prenatally to simulated labor contractions and delivered by cesarean section breath and attach to nipples at greater frequencies than non-stimulated fetuses. Plasma NE (norepinephrine) and EPI (epinephrine) was significantly elevated in newborn rats exposed to vaginal birth or simulated labor contractions (compressions) with cesarean delivery as compared to non-compressed fetuses. In the present study, we investigated adrenergic mechanisms underlying labor-induced postnatal adaptive responses. Following spinal transection of late pregnant rat dams, fetuses were administered neurogenic or non-neurogenic adrenergic blockade: 1) bretylium (10 mg/kg sc) to prevent sympathetic neuronal release, 2) hexamethonium (30 mg/kg) to produce ganglionic blockade, 3) phenoxybenzanune (10mg/kg sc), an a- adrenergic receptor antagonist, 4) ICI-118551, 10 mg/kg sc), a b receptor antagonist, or 5) vehicle alone. Fetuses were either compressed (C) or non-compressed (NC) prior to cesarean delivery. a- and b- adrenergic antagonists reduced respiration and nipple attachment rates while sympathetic and vehicle alone did not. These results provide additional support for the hypothesis that adaptive neonatal effects of labor contractions are mediated by adrenal and extra-adrenal catecholamines.

Nicotine promotes cell proliferation via {alpha}7-nicotinic acetylcholine receptor and catecholamine-synthesizing enzymes-mediated pathway in human colon adenocarcinoma HT-29 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Helen Pui Shan; Yu Le; Lam, Emily Kai Yee

Cigarette smoking has been implicated in colon cancer. Nicotine is a major alkaloid in cigarette smoke. In the present study, we showed that nicotine stimulated HT-29 cell proliferation and adrenaline production in a dose-dependent manner. The stimulatory action of nicotine was reversed by atenolol and ICI 118,551, a {beta}{sub 1}- and {beta}{sub 2}-selective antagonist, respectively, suggesting the role of {beta}-adrenoceptors in mediating the action. Nicotine also significantly upregulated the expression of the catecholamine-synthesizing enzymes [tyrosine hydroxylase (TH), dopamine-{beta}-hydroxylase (D{beta}H) and phenylethanolamine N-methyltransferase]. Inhibitor of TH, a rate-limiting enzyme in the catecholamine-biosynthesis pathway, reduced the actions of nicotine on cell proliferationmore » and adrenaline production. Expression of {alpha}7-nicotinic acetylcholine receptor ({alpha}7-nAChR) was demonstrated in HT-29 cells. Methyllycaconitine, an {alpha}7-nAChR antagonist, reversed the stimulatory actions of nicotine on cell proliferation, TH and D{beta}H expression as well as adrenaline production. Taken together, through the action on {alpha}7-nAChR nicotine stimulates HT-29 cell proliferation via the upregulation of the catecholamine-synthesis pathway and ultimately adrenaline production and {beta}-adrenergic activation. These data reveal the contributory role {alpha}7-nAChR and {beta}-adrenoceptors in the tumorigenesis of colon cancer cells and partly elucidate the carcinogenic action of cigarette smoke on colon cancer.« less

Adrenergic beta 2-selective blocker in isoprenaline-enhanced essential tremor.

PubMed

Teräväinen, H; Huttunen, J

1987-01-01

A beta 2-selective adrenergic-receptor-blocking drug, ICI 118.551, 150 mg/day, prevented almost as effectively as the nonselective antagonist propranolol, 240 mg/day, the isoprenaline enhancement of essential tremor amplitude.

[Effect of non-selective alpha-adrenergic receptor antagonist nicergoline on the activity of neurons in the ventral lateral thalamic nucleus].

PubMed

Lukhanina, O P; Pil'kevych, N A

2005-01-01

In experiments on rats microionophoretic administration of nicergoline mainly showed the dual effect on the background activity of the ventrolateral thalamic nucleus (VL) neurons and their reactions evoked by the superior cerebellum peduncle stimulation: inhibitory under weak (2-10 nA) and excitatory under stronger (20-40 nA) currents. Microionophoresis (25 nA) of nicergoline led to decrease of the postexcitatory inhibitory processes during paired stimulation of the cerebellum fibers. Paired-pulse ratio (number of spikes in the short-latency neuronal responses elicited by the second pulse/number of spikes by the first pulse) increased, which support a presynaptic mode of drug action. Hence excitatory effect of nicergoline may be related to the blockade of the presynaptic alpha2-receptors, while inhibitory effect by the blockade of the postsynaptic alphal-receptors. Present data reveal the essential participation of the alpha-adrenoreceptor system in the modulation of background and evoked neuronal activity of the motor thalamus. The possible role of noradrenergic denervation in the development of movement disorders accompanying Parkinson's disease is discussed.

Calcium antagonism: aldosterone and vascular responses to catecholamines and angiotensin II in man.

PubMed

Elliott, H L

1993-12-01

Effects of calcium antagonists on pressor mechanisms: A number of differences have been reported in the variable extent to which calcium antagonists interfere with various pressor mechanisms. In theory, high lipid solubility, membrane-binding characteristics and a prolonged duration of action appear to be requirements for a calcium antagonist to affect mechanisms such as vasodilation, endogenous vasoconstrictor responses, hormone release and natriuretic activity. Reduction in peripheral vascular resistance: A reduction in peripheral vascular resistance is fundamental to the antihypertensive effect not only of calcium antagonists but also of angiotensin converting enzyme inhibitors and alpha 1-adrenoceptor antagonists. However, only the calcium antagonists interfere directly with the pressor responses mediated by both the adrenergic nervous system and the renin-angiotensin system. Mechanism of lacidipine effects: Preliminary results with the new dihydropyridine calcium antagonist lacidipine indicate that it not only has vasodilator activity but that it also interferes with both adrenergic and non-adrenergic endogenous vasoconstrictor mechanisms. This may provide additional potentially beneficial cardiovascular effects, particularly in relation to left ventricular hypertrophy and dysfunction.

Neurotransmitter-mediated anxiogenic action of PACAP-38 in rats.

PubMed

Telegdy, G; Adamik, A

2015-03-15

The action of PACAP-38 was studied by measuring the anxiogenic-anxiolytic behavior of rats in an elevated plus maze. PACAP-38 was administered into the lateral brain ventricle and the behavior of the animals was measured 3h later. The possible involvement of transmitters was measured by pretreating the animals with receptor blockers which alone did not influence the task, but in the doses used were effective with other neuropeptides. The receptor antagonist PACAP 6-38 (a PAC 1/VPAC2 receptor antagonist of PACAP-38 receptor), haloperidol (a non-selective dopamine receptor antagonist), phenoxybenzamine (an α1/α2β-adrenergic receptor antagonist), propranolol(a β-adrenergic receptor antagonist), bicuculline (a gamma-aminobutyric acid subunit A receptor antagonist), methysergide (a nonselective 5-HT2 serotonergic receptor antagonist), atropine (a nonselective muscarinic acetylcholine receptor antagonist), naloxone (a nonselective opioid receptor antagonist) and nitro-l-arginine which acts by blocking the enzyme nitric oxide synthase, thereby blocking the nitric oxide synthesis, were tested. The following parameters were measured: the time spent in open arms/the time spent in total entries. PACAP-38 decreased the ratio of time spent in open arms to the time spent in total entries, indicating anxiogenic action. The total number of entries was not altered significantly either by PACAP-38 or by the receptor blockers. The following receptor blockers diminished the action of PACAP-38: PACAP 6-38,haloperidol, methysergide, naloxone and nitro-l-arginine. Pretreatment with atropine, phenoxybenzamine, propranolol and bicuculline did not influence the action of PACAP-38 on the time spent in open arms. The results demonstrate that PACAP-38 administered into the lateral brain ventricle exerted anxiogenic action at 3 h following treatment. Pretreatment of the animals with various receptor blockers indicated that a nonselective dopaminergic receptor antagonist, 5HT2 serotonergic and opioid receptors, nitric oxide and PAC1 receptors are involved in the anxiogenic action induced by PACAP-38. Copyright © 2014 Elsevier B.V. All rights reserved.

The effects of increasing doses of MK-467, a peripheral alpha(2)-adrenergic receptor antagonist, on the cardiopulmonary effects of intravenous dexmedetomidine in conscious dogs.

PubMed

Honkavaara, J M; Restitutti, F; Raekallio, M R; Kuusela, E K; Vainio, O M

2011-08-01

Different doses of MK-467, a peripheral alpha(2)-adrenergic receptor antagonist, with or without dexmedetomidine were compared in conscious dogs. Eight animals received either dexmedetomidine (10 μg/kg [D]), MK-467 (250 μg/kg [M250] or dexmedetomidine (10 μg/kg) with increasing doses of MK-467 (250 μg/kg [DM250], 500 μg/kg [DM500] and 750 μg/kg [DM750], respectively). Treatments were given intravenously (i.v.) in a randomized, crossover design with a 14-day washout period. Systemic hemodynamics and arterial blood gas analyses were recorded at baseline and at intervals up to 90 min after drugs administration. Dexmedetomidine alone decreased heart rate, cardiac index and tissue oxygen delivery and increased mean arterial pressure and systemic vascular resistance 5 min after administration. DM250 did not completely prevent these early effects, while DM750 induced a decrease in mean arterial pressure. With DM500, systemic hemodynamics remained stable throughout the observational period. MK-467 alone increased cardiac index and tissue oxygen delivery and had no deleterious adverse effects. No differences in arterial blood gases were observed between treatments that included dexmedetomidine. It was concluded that MK-467 attenuated or prevented dexmedetomidine's systemic hemodynamic effects in a dose-dependent manner when given simultaneously i.v. but had no effect on the pulmonary outcome in conscious dogs. A 50:1 dose ratio (MK-467:dexmedetomidine) induced the least alterations in cardiovascular function. © 2010 Blackwell Publishing Ltd.

Effects of β-adrenergic receptor blockade on drug-related memory reconsolidation in abstinent heroin addicts.

PubMed

Zhao, Li-Yan; Sun, Li-Li; Shi, Jie; Li, Peng; Zhang, Yan; Lu, Lin

2011-11-01

The reactivation of a consolidated memory can return it to a labile state, a process referred to as reconsolidation. A previous study showed that oral administration of the β-adrenergic receptor antagonist propranolol before memory reactivation in humans erased the behavioral expression of the fear memory 24h later. In this study, we investigated whether propranolol impairs the drug-related memory by disrupting the reconsolidation process in heroin addicts. Seventy abstinent heroin addicts learned a word list (including 10 heroin-related positive words, 10 heroin-related negative words, and 10 neutral words) on day 1. Participants orally administered the β-adrenergic receptor antagonist propranolol or placebo before retrieval of the word list on day 2. Free recall of the word list and other psychological and physical responses were assessed on day 3. Oral administration of propranolol before reactivation of the word list impaired reconsolidation of drug-related positive and negative but not neutral words in abstinent heroin addicts, and these impairments critically depended on reactivation of the word list. This study extends earlier reports that a β-adrenergic receptor antagonist affects the drug-related memory reconsolidation process. Our findings may have important implications for the understanding and treatment of persistent and abnormal drug-related memories in abstinent heroin addicts. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The involvement of peripheral alpha 2-adrenoceptors in the antihyperalgesic effect of oxcarbazepine in a rat model of inflammatory pain.

PubMed

Tomić, Maja A; Vucković, Sonja M; Stepanović-Petrović, Radica M; Ugresić, Nenad D; Paranos, Sonja Lj; Prostran, Milica S; Bosković, Bogdan

2007-11-01

We studied whether peripheral alpha2-adrenergic receptors are involved in the antihyperalgesic effects of oxcarbazepine by examining the effects of yohimbine (selective alpha2-adrenoceptor antagonist), BRL 44408 (selective alpha(2A)-adrenoceptor antagonist), MK-912 (selective alpha2C-adrenoceptor antagonist), and clonidine (alpha2-adrenoceptor agonist) on the antihyperalgesic effect of oxcarbazepine in the rat model of inflammatory pain. Rats were intraplantarly (i.pl.) injected with the proinflammatory compound concanavalin A (Con A). A paw-pressure test was used to determine: 1) the development of hyperalgesia induced by Con A; 2) the effects of oxcarbazepine (i.pl.) on Con A-induced hyperalgesia; and 3) the effects of i.pl. yohimbine, BRL 44408, MK-912 and clonidine on the oxcarbazepine antihyperalgesia. Both oxcarbazepine (1000-3000 nmol/paw; i.pl.) and clonidine (1.9-7.5 nmol/paw; i.pl.) produced a significant dose-dependent reduction of the paw inflammatory hyperalgesia induced by Con A. Yohimbine (260 and 520 nmol/paw; i.pl.), BRL 44408 (100 and 200 nmol/paw; i.pl.) and MK-912 (10 and 20 nmol/paw; i.pl.) significantly depressed the antihyperalgesic effects of oxcarbazepine (2000 nmol/paw; i.pl.) in a dose-dependent manner. The effects of antagonists were due to local effects since they were not observed after administration into the contralateral hindpaw. Oxcarbazepine and clonidine administered jointly in fixed-dose fractions of the ED(50) (1/4, 1/2, and 3/4) caused significant and dose-dependent reduction of hyperalgesia induced by Con A. Isobolographic analysis revealed an additive antihyperalgesic effect. Our results indicate that the peripheral alpha2A and alpha2C adrenoceptors could be involved in the antihyperalgesic effects of oxcarbazepine in a rat model of inflammatory hyperalgesia.

The alpha1-adrenergic antagonist prazosin ameliorates combat trauma nightmares in veterans with posttraumatic stress disorder: a report of 4 cases.

PubMed

Raskind, M A; Dobie, D J; Kanter, E D; Petrie, E C; Thompson, C E; Peskind, E R

2000-02-01

Central nervous system (CNS) adrenergic hyperresponsiveness may be involved in the pathophysiology of posttraumatic stress disorder (PTSD). Two Vietnam combat veterans with PTSD prescribed the centrally active alpha1-adrenergic antagonist prazosin for symptoms of benign prostatic hypertrophy unexpectedly reported elimination of combat trauma nightmares. This observation prompted an open-label feasibility trial of prazosin for combat trauma nightmares in chronic combat-induced PTSD. Four consecutively identified combat veterans with chronic DSM-IV PTSD and severe intractable combat trauma nightmares participated in an 8-week open trial of escalating-dose prazosin. Nightmare severity response was rated using the nightmare item of the Clinician Administered PTSD Scale and the Clinical Global Impressions-Change scale. The 2 patients who achieved a daily prazosin dose of at least 5 mg were markedly improved, with complete elimination of trauma nightmares and resumption of normal dreaming. The 2 subjects limited to 2 mg of prazosin to avoid excessive blood pressure reduction were moderately improved with at least 50% reduction in nightmare severity. These clinical observations, together with neurobiological evidence for alpha1-adrenergic regulation of CNS neurobiological systems relevant to PTSD, provide rationale for placebo-controlled trials of prazosin for PTSD combat trauma nightmares.

A new Drosophila octopamine receptor responds to serotonin.

PubMed

Qi, Yi-Xiang; Xu, Gang; Gu, Gui-Xiang; Mao, Fen; Ye, Gong-Yin; Liu, Weiwei; Huang, Jia

2017-11-01

As the counterparts of the vertebrate adrenergic transmitters, octopamine and tyramine are important physiological regulators in invertebrates. They control and modulate many physiological and behavioral functions in insects. In this study, we reported the pharmacological properties of a new α2-adrenergic-like octopamine receptor (CG18208) from Drosophila melanogaster, named DmOctα2R. This new receptor gene encodes two transcripts by alternative splicing. The long isoform DmOctα2R-L differs from the short isoform DmOctα2R-S by the presence of an additional 29 amino acids within the third intracellular loop. When heterologously expressed in mammalian cell lines, both receptors were activated by octopamine, tyramine, epinephrine and norepinephrine, resulting in the inhibition of cAMP production in a dose-dependent manner. The long form is more sensitive to the above ligands than the short form. The adrenergic agonists naphazoline, tolazoline and clonidine can stimulate DmOctα2R as full agonists. Surprisingly, serotonin and serotoninergic agonists can also activate DmOctα2R. Several tested adrenergic antagonists and serotonin antagonists blocked the action of octopamine or serotonin on DmOctα2R. The data presented here reported an adrenergic-like G protein-coupled receptor activated by serotonin, suggesting that the neurotransmission and neuromodulation in the nervous system could be more complex than previously thought. Copyright © 2017 Elsevier Ltd. All rights reserved.

Infusion of adrenergic receptor agonists and antagonists into the locus coeruleus and ventricular system of the brain. Effects on swim-motivated and spontaneous motor activity.

PubMed

Weiss, J M; Simson, P G; Hoffman, L J; Ambrose, M J; Cooper, S; Webster, A

1986-04-01

These studies examined how pharmacological stimulation and blockade of alpha receptors would affect active motor behavior in rats. In experiment I, alpha-2 receptor antagonists (piperoxane, yohimbine) and agonists [clonidine, norepinephrine (NE)] were infused into various locations in the ventricular system of the brain, including the locus coeruleus region, and motor activity was measured. Activity was measured principally in a swim test but spontaneous (ambulatory) activity was also recorded while drugs were being infused. When infused into the locus coeruleus region, small doses of the antagonists piperoxane and yohimbine depressed activity in the swim test while infusion of the agonists clonidine and NE had the opposite effect of stimulating activity. These effects were highly specific to the region of the locus coeruleus, since infusions of these drugs into other nearby locations in the ventricular system or use of larger doses had different, often opposite effects. This was especially true of clonidine and NE which profoundly depressed activity when infused posterior to the locus coeruleus, particularly over the dorsal vagal complex. Infusion of small doses of these drugs into the lateral ventricle had effects similar to infusion into the locus coeruleus region, though less pronounced. Changes in spontaneous motor activity were also observed, but this measure differentiated the groups less well than did the swim test. In experiment II, the predominantly postsynaptic receptor agonists isoproterenol (beta agonist) and phenylephrine (alpha-1 agonist) were infused into the ventricular system. Since infusions of piperoxane and yohimbine into the locus coeruleus that decreased activity in experiment I increase the release of NE by blocking alpha-2 inhibitory receptors on cell bodies and dendrites of the locus coeruleus, experiment II tested whether ventricular infusion of predominantly postsynaptic receptor agonists would also decrease activity in the swim test. Both isoproterenol and phenylephrine produced this effect, but did so selectively with respect to dose and location of infusion in the ventricular system. These findings are consistent with recent results relating to the mechanism that underlies stress-induced depression of active behavior.

Development of serotonergic and adrenergic receptors in the rat spinal cord: effects of neonatal chemical lesions and hyperthyroidism.

PubMed

Lau, C; Pylypiw, A; Ross, L L

1985-03-01

The sympathetic preganglionic neurons in the spinal cord receive dense serotonergic (5-HT) and catecholaminergic (CA) afferent inputs from the descending supraspinal pathways. In the rat spinal cord, the levels of these biogenic amines and their receptors are low at birth, but undergo rapid ontogenetic increases in the ensuing 2-3 postnatal weeks until the adult levels are reached. In many systems it has been shown that denervation of presynaptic neurons leads to an up-regulation of the number of postsynaptic receptors. To determine whether the 5-HT and CA receptors in the developing spinal cord are also subject to such transsynaptic regulation, we examined the ontogeny of serotonergic receptors and alpha- and beta-adrenergic receptors in thoracolumbar spinal cord of rats given neurotoxins which destroy serotonergic (5,7-dihydroxytryptamine (5,7-DHT)) or noradrenergic (6-hydroxydopamine (6-OHDA)) nerve terminals. Intracisternal administration of 5,7-DHT or 6-OHDA at 1 and 6 days of age prevented, respectively, the development of 5-HT and CA levels in the spinal cord. Rats lesioned with 5,7-DHT displayed a marked elevation of 5-HT receptors with a binding of 50% greater than controls at 1 week and a continuing increase to twice normal by 4 weeks. A similar pattern of up-regulation was also detected with the alpha-adrenergic receptor, as rats lesioned with 6-OHDA exhibited persistent increases in receptor concentration. However, in these same animals ontogeny of the beta-adrenergic receptor in the spinal cord remained virtually unaffected by the chemical lesion. In several other parts of the nervous system, it has been demonstrated that the beta-adrenergic sensitivity can be modulated by hormonal signals, particularly that of the thyroid hormones. This phenomenon was examined in the spinal cord and in confirmation with previous studies neonatal treatment of triiodothyronine (0.1 mg/kg, s.c. daily) was capable of evoking persistent increases in beta-adrenergic receptor binding. These results suggest that: (a) development of the postjunctional serotonergic and alpha-adrenergic receptors in the rat spinal cord can occur in the absence of the prejunctional nerve terminals and are subject to transsynaptic modulation; (b) beta-adrenergic receptors in the spinal cord also can develop after prejunctional lesions but are regulated by hormonal rather than neuronal factors.

β2-Adrenergic Receptor Activation Suppresses the Rat Phenethylamine Hallucinogen-Induced Head Twitch Response: Hallucinogen-Induced Excitatory Post-synaptic Potentials as a Potential Substrate

PubMed Central

Marek, Gerard J.; Ramos, Brian P.

2018-01-01

5-Hydroxytryptamine2A (5-HT2A) receptors are enriched in layers I and Va of the rat prefrontal cortex and neocortex and their activation increases the frequency of glutamatergic excitatory post-synaptic potentials/currents (EPSP/Cs) onto layer V pyramidal cells. A number of other G-protein coupled receptors (GPCRs) are also enriched in cortical layers I and Va and either induce (α1-adrenergic and orexin2) or suppress (metabotropic glutamate2 [mGlu2], adenosine A1, μ-opioid) both 5-HT-induced EPSCs and head twitches or head shakes induced by the phenethylamine hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI). Another neurotransmitter receptor also localized to apparent thalamocortical afferents to layers I and Va of the rat prefrontal cortex and neocortex is the β2-adrenergic receptor. Therefore, we conducted preliminary electrophysiological experiments with rat brain slices examining the effects of epinephrine on electrically-evoked EPSPs following bath application of DOI (3 μM). Epinephrine (0.3–10 μM) suppressed the late EPSPs produced by electrical stimulation and DOI. The selective β2-adrenergic receptor antagonist ICI-118,551 (300 nM) resulted in a rightward shift of the epinephrine concentration-response relationship. We also tested the selective β2-adrenergic receptor agonist clenbuterol and the antagonist ICI-118,551 on DOI-induced head twitches. Clenbuterol (0.3–3 mg/kg, i.p.) suppressed DOI (1.25 mg/kg, i.p.)-induced head twitches. This clenbuterol effect appeared to be at least partially reversed by the selective β2-adrenergic receptor antagonist ICI-118,553 (0.01–1 mg/kg, i.p.), with significant reversal at doses of 0.1 and 1 mg/kg. Thus, β2-adrenergic receptor activation reverses the effects of phenethylamine hallucinogens in the rat prefrontal cortex. While Gi/Go-coupled GPCRs have previously been shown to suppress both the electrophysiological and behavioral effects of 5-HT2A receptor activation in the mPFC, the present work appears to extend this suppressant action to a Gs-coupled GPCR. Furthermore, the modulation of 5-HT2A receptor activation-induced glutamate release onto mPFC layer V pyramidal neurons apical dendrites by a range GPCRs in rat brain slices appears to results in behaviorally salient effects of relevance when screening for novel CNS therapeutic drugs. PMID:29472863

Neuroendocrine mediators up-regulate alpha1b- and alpha1d-adrenergic receptor subtypes in human monocytes.

PubMed

Rouppe van der Voort, C; Kavelaars, A; van de Pol, M; Heijnen, C J

1999-03-01

Beta2- and alpha2-adrenergic receptors (AR) are thought to be the main AR subtypes to exert the effects of catecholamines on the immune system. However, in the present study, we demonstrate that another subtype of AR can be induced in human monocytes. Expression of alpha1b- and alpha1d-AR mRNA can be obtained by culturing freshly isolated human peripheral blood monocytes with the neuroendocrine mediators dexamethasone or the beta2-AR agonist terbutaline. Using the human monocytic cell line THP-1, we demonstrate that increased levels of alpha1b- and alpha1d-mRNA are accompanied by increased levels of receptor protein as determined by Western blot analysis and radioligand binding assays. This study describes for the first time regulated expression of alpha1-AR subtypes in human monocytes.

Role of a guanine nucleotide-binding protein in. cap alpha. /sub 1/-adrenergic receptor-mediated Ca/sup 2 +/ mobilization in DDT/sub 1/ MF-2 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cornett, L.E.; Norris, J.S.

1987-11-01

In this study the mechanisms involved in ..cap alpha../sub 1/-adrenergic receptor-mediated Ca/sup 2 +/ mobilization at the level of the plasma membrane were investigated. Stimulation of /sup 45/Ca/sup 2 +/ efflux from saponin-permeabilized DDT/sub 1/ MF-2 cells was observed with the addition of either the ..cap alpha../sub 1/-adrenergic agonist phenylephrine and guanosine-5'-triphosphate or the nonhydrolyzable guanine nucleotide guanylyl-imidodiphosphate. In the presence of (/sup 32/P) NAD, pertussis toxin was found to catalyze ADP-ribosylation of a M/sub r/ = 40,500 (n = 8) peptide in membranes prepared from DDT/sub 1/, MF-2 cells, possibly the ..cap alpha..-subunit of N/sub i/. However, stimulation ofmore » unidirectional /sup 45/Ca/sup 2 +/ efflux by phenylephrine was not affected by previous treatment of cells with 100 ng/ml pertussis toxin. These data suggest that the putative guanine nucleotide-binding protein which couples the ..cap alpha../sub 1/-adrenergic receptor to Ca/sup 2 +/ mobilization in DDT/sub 1/ MF-2 cells is not a pertussis toxin substrate and may possibly be an additional member of guanine nucleotide binding protein family.« less

LSD and DOB: interaction with 5-HT2A receptors to inhibit NMDA receptor-mediated transmission in the rat prefrontal cortex.

PubMed

Arvanov, V L; Liang, X; Russo, A; Wang, R Y

1999-09-01

Both the phenethylamine hallucinogen (-)-1-2, 5-dimethoxy-4-bromophenyl-2-aminopropane (DOB), a selective serotonin 5-HT2A,2C receptor agonist, and the indoleamine hallucinogen D-lysergic acid diethylamide (LSD, which binds to 5-HT1A, 1B, 1D, 1E, 1F, 2A, 2C, 5, 6, 7, dopamine D1 and D2, and alpha1 and alpha2 adrenergic receptors), but not their non-hallucinogenic congeners, inhibited N-methyl-D-aspartate (NMDA)-induced inward current and NMDA receptor-mediated synaptic responses evoked by electrical stimulation of the forceps minor in pyramidal cells of the prefrontal cortical slices. The inhibitory effect of hallucinogens was mimicked by 5-HT in the presence of selective 5-HT1A and 5-HT3 receptor antagonists. The inhibitory action of DOB, LSD and 5-HT on the NMDA transmission was blocked by the 5-HT2A receptor antagonists R-(+)-alpha-(2, 3-dimethoxyphenil)-1-[4-fluorophenylethyl]-4-piperidineme thanol (M100907) and ketanserin. However, at low concentrations, when both LSD and DOB by themselves only partially depressed the NMDA response, they blocked the inhibitory effect of 5-HT, suggesting a partial agonist action. Whereas N-(4-aminobutyl)-5-chloro-2-naphthalenesulphonamide (W-7, a calmodulin antagonist) and N-[2-[[[3-(4'-chlorophenyl)- 2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4'-methoxy-b enzenesulphonamide phosphate (KN-93, a Ca2+/CaM-KII inhibitor), but not the negative control 2-[N-4'methoxybenzenesulphonyl]amino-N-(4'-chlorophenyl)-2-propeny l-N -methylbenzylamine phosphate (KN-92), blocked the inhibitory action of LSD and DOB, the selective protein kinase C inhibitor chelerythrine was without any effect. We conclude that phenethylamine and indoleamine hallucinogens may exert their hallucinogenic effect by interacting with 5-HT2A receptors via a Ca2+/CaM-KII-dependent signal transduction pathway as partial agonists and modulating the NMDA receptors-mediated sensory, perceptual, affective and cognitive processes.

Antinociceptive effect of intrathecal microencapsulated human pheochromocytoma cell in a rat model of bone cancer pain.

PubMed

Li, Xiao; Li, Guoqi; Wu, Shaoling; Zhang, Baiyu; Wan, Qing; Yu, Ding; Zhou, Ruijun; Ma, Chao

2014-07-08

Human pheochromocytoma cells, which are demonstrated to contain and release met-enkephalin and norepinephrine, may be a promising resource for cell therapy in cancer-induced intractable pain. Intrathecal injection of alginate-poly (l) lysine-alginate (APA) microencapsulated human pheochromocytoma cells leads to antinociceptive effect in a rat model of bone cancer pain, and this effect was blocked by opioid antagonist naloxone and alpha 2-adrenergic antagonist rauwolscine. Neurochemical changes of cerebrospinal fluid are in accordance with the analgesic responses. Taken together, these data support that human pheochromocytoma cell implant-induced antinociception was mediated by met-enkephalin and norepinephrine secreted from the cell implants and acting at spinal receptors. Spinal implantation of microencapsulated human pheochromocytoma cells may provide an alternative approach for the therapy of chronic intractable pain.

Summaries of Research 1986

DTIC Science & Technology

1986-01-01

PSEUDOMONAS AERUGINOSA AD A177 399 NMRI 86-0009 3CMILLAN M CHERNOW B ROTH BL PHOROOL ESTERS INHIBIT ALPHA I-ADRENERGIC RECEPTOR- STIlULATED...PHORBOL ESTERS PHOSPHOINOSITIDES RATS RECEPTORS, ADRENERGIC, ALPHA TASOMOTOR SYSTEM AD A171 091 NMRI 86-0010 QUESADA M MILLAR DB SMEJKAL R TUEULIN SYNTHESIS...UPTAKE AND RELEASE OF CALCIUM BY BRAIN SYNAPTOSOMES. JOURNAL OF APPLIED PHYSIOLOGY 1966 APR;60(4):1446-50 HYPERBARIC MEDICINE MRO41.O.1.1124 REPORT NO

[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…

Silodosin for the treatment of clinical benign prostatic hyperplasia: safety, efficacy, and patient acceptability.

PubMed

Cho, Hee Ju; Yoo, Tag Keun

2014-01-01

α1-Adrenergic receptor antagonists are commonly used to treat male lower urinary tract symptoms and benign prostatic hyperplasia (BPH). We performed a literature search using PubMed, Medline via Ovid, Embase, and the Cochrane Library databases to identify studies on the treatment of BPH by silodosin. Silodosin is a novel α1-adrenergic receptor antagonist whose affinity for the α1A-adrenergic receptor is greater than that for the α1B-adrenergic receptor. Therefore, silodosin does not increase the incidence of blood pressure-related side effects, which may result from the inhibition of the α1B-adrenergic receptor. Patients receiving silodosin at a daily dose of 8 mg showed a significant improvement in the International Prostate Symptom Score and maximum urinary flow rate compared with those receiving a placebo. Silodosin also improved both storage and voiding symptoms, indicating that silodosin is effective, even during early phases of BPH treatment. Follow-up extension studies performed in the United States, Europe, and Asia demonstrated its long-term safety and efficacy. In the European study, silodosin significantly reduced nocturia compared to the placebo. Although retrograde or abnormal ejaculation was the most commonly reported symptom in these studies, only a few patients discontinued treatment. The incidence of adverse cardiovascular events was also very low. Evidence showing solid efficacy and cardiovascular safety profiles of silodosin will provide a good solution for the treatment of lower urinary tract symptoms associated with BPH in an increasingly aging society.

Silodosin for the treatment of clinical benign prostatic hyperplasia: safety, efficacy, and patient acceptability

PubMed Central

Cho, Hee Ju; Yoo, Tag Keun

2014-01-01

α1-Adrenergic receptor antagonists are commonly used to treat male lower urinary tract symptoms and benign prostatic hyperplasia (BPH). We performed a literature search using PubMed, Medline via Ovid, Embase, and the Cochrane Library databases to identify studies on the treatment of BPH by silodosin. Silodosin is a novel α1-adrenergic receptor antagonist whose affinity for the α1A-adrenergic receptor is greater than that for the α1B-adrenergic receptor. Therefore, silodosin does not increase the incidence of blood pressure-related side effects, which may result from the inhibition of the α1B-adrenergic receptor. Patients receiving silodosin at a daily dose of 8 mg showed a significant improvement in the International Prostate Symptom Score and maximum urinary flow rate compared with those receiving a placebo. Silodosin also improved both storage and voiding symptoms, indicating that silodosin is effective, even during early phases of BPH treatment. Follow-up extension studies performed in the United States, Europe, and Asia demonstrated its long-term safety and efficacy. In the European study, silodosin significantly reduced nocturia compared to the placebo. Although retrograde or abnormal ejaculation was the most commonly reported symptom in these studies, only a few patients discontinued treatment. The incidence of adverse cardiovascular events was also very low. Evidence showing solid efficacy and cardiovascular safety profiles of silodosin will provide a good solution for the treatment of lower urinary tract symptoms associated with BPH in an increasingly aging society. PMID:25328864

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lepor, H.; Rigaud, G.; Shapiro, E.

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

Antinociceptive Activity of Methanolic Extract of Clinacanthus nutans Leaves: Possible Mechanisms of Action Involved

PubMed Central

Abdul Rahim, Mohammad Hafiz; Roosli, Rushduddin Al Jufri; Othman, Fezah

2018-01-01

Methanolic extract of Clinacanthus nutans Lindau leaves (MECN) has been proven to possess antinociceptive activity that works via the opioid and NO-dependent/cGMP-independent pathways. In the present study, we aimed to further determine the possible mechanisms of antinociception of MECN using various nociceptive assays. The antinociceptive activity of MECN was (i) tested against capsaicin-, glutamate-, phorbol 12-myristate 13-acetate-, bradykinin-induced nociception model; (ii) prechallenged against selective antagonist of opioid receptor subtypes (β-funaltrexamine, naltrindole, and nor-binaltorphimine); (iii) prechallenged against antagonist of nonopioid systems, namely, α2-noradrenergic (yohimbine), β-adrenergic (pindolol), adenosinergic (caffeine), dopaminergic (haloperidol), and cholinergic (atropine) receptors; (iv) prechallenged with inhibitors of various potassium channels (glibenclamide, apamin, charybdotoxin, and tetraethylammonium chloride). The results demonstrated that the orally administered MECN (100, 250, and 500 mg/kg) significantly (p < 0.05) reversed the nociceptive effect of all models in a dose-dependent manner. Moreover, the antinociceptive activity of 500 mg/kg MECN was significantly (p < 0.05) inhibited by (i) antagonists of μ-, δ-, and κ-opioid receptors; (ii) antagonists of α2-noradrenergic, β-adrenergic, adenosinergic, dopaminergic, and cholinergic receptors; and (iii) blockers of different K+ channels (voltage-activated-, Ca2+-activated, and ATP-sensitive-K+ channels, resp.). In conclusion, MECN-induced antinociception involves modulation of protein kinase C-, bradykinin-, TRVP1 receptors-, and glutamatergic-signaling pathways; opioidergic, α2-noradrenergic, β-adrenergic, adenosinergic, dopaminergic, and cholinergic receptors; and nonopioidergic receptors as well as the opening of various K+ channels. The antinociceptive activity could be associated with the presence of several flavonoid-based bioactive compounds and their synergistic action with nonvolatile bioactive compounds. PMID:29686743

Anxiolytic action of neuromedin-U and neurotransmitters involved in mice.

PubMed

Telegdy, G; Adamik, A

2013-09-10

Peptide Neuromedin-U (NmU) is widely distributed in the central nervous system and the peripheral tissues. Its physiological effects include the regulation of blood pressure, heart rate, and body temperature, and the inhibition of gastric acid secretion. The action of NmU in rats is mediated by two G-protein-coupled receptors, NmU-1R and NmU-2R. NmU-2R is present mainly in the brain, and NmU-1R mainly in the periphery. Despite the great variety of the physiological action of NmU, little is known about its possible effects in different forms of behavior, such as anxiety. In the present work, NmU-23 (the rodent form of the peptide) was tested for its effect on anxiety in elevated plus maze test in mice. For detection of the possible involvement of neurotransmitters, the mice were pretreated with receptor blockers: haloperidol (a D2, dopamine receptor antagonist), propranolol (a β-adrenergic receptor antagonist), atropine (a nonselective muscarinic acetylcholine receptor antagonist), phenoxybenzamine (a nonselective α-adrenergic receptor antagonist) or nitro-l-arginine (a nitric oxide synthase inhibitor). The peptide and nitro-l-arginine were administered into the lateral brain ventricle, while the receptor blockers were applied intraperitoneally. An NmU-23 dose 0.5μg elicited anxiolytic action, whereas this action is faded away when the dose was increased. For further testing therefore 0.5μg i.c.v. was used. Propranolol and atropine fully blocked the NmU-induced anxiolytic action, while haloperidol, phenoxybenzamine and nitro-l-arginine were ineffective. The results suggest that β-adrenergic and cholinergic mechanisms are involved in the anxiolytic action of NmU. © 2013.

Blocking beta 2-adrenergic receptor inhibits dendrite ramification in a mouse model of Alzheimer's disease.

PubMed

Wu, Qin; Sun, Jin-Xia; Song, Xiang-He; Wang, Jing; Xiong, Cun-Quan; Teng, Fei-Xiang; Gao, Cui-Xiang

2017-09-01

Dendrite ramification affects synaptic strength and plays a crucial role in memory. Previous studies revealed a correlation between beta 2-adrenergic receptor dysfunction and Alzheimer's disease (AD), although the mechanism involved is still poorly understood. The current study investigated the potential effect of the selective β 2 -adrenergic receptor antagonist, ICI 118551 (ICI), on Aβ deposits and AD-related cognitive impairment. Morris water maze test results demonstrated that the performance of AD-transgenic (TG) mice treated with ICI (AD-TG/ICI) was significantly poorer compared with NaCl-treated AD-TG mice (AD-TG/NaCl), suggesting that β 2 -adrenergic receptor blockage by ICI might reduce the learning and memory abilities of mice. Golgi staining and immunohistochemical staining revealed that blockage of the β 2 -adrenergic receptor by ICI treatment decreased the number of dendritic branches, and ICI treatment in AD-TG mice decreased the expression of hippocampal synaptophysin and synapsin 1. Western blot assay results showed that the blockage of β 2 -adrenergic receptor increased amyloid-β accumulation by downregulating hippocampal α-secretase activity and increasing the phosphorylation of amyloid precursor protein. These findings suggest that blocking the β 2 -adrenergic receptor inhibits dendrite ramification of hippocampal neurons in a mouse model of AD.

Blocking beta 2-adrenergic receptor inhibits dendrite ramification in a mouse model of Alzheimer's disease

PubMed Central

Wu, Qin; Sun, Jin-xia; Song, Xiang-he; Wang, Jing; Xiong, Cun-quan; Teng, Fei-xiang; Gao, Cui-xiang

2017-01-01

Dendrite ramification affects synaptic strength and plays a crucial role in memory. Previous studies revealed a correlation between beta 2-adrenergic receptor dysfunction and Alzheimer's disease (AD), although the mechanism involved is still poorly understood. The current study investigated the potential effect of the selective β2-adrenergic receptor antagonist, ICI 118551 (ICI), on Aβ deposits and AD-related cognitive impairment. Morris water maze test results demonstrated that the performance of AD-transgenic (TG) mice treated with ICI (AD-TG/ICI) was significantly poorer compared with NaCl-treated AD-TG mice (AD-TG/NaCl), suggesting that β2-adrenergic receptor blockage by ICI might reduce the learning and memory abilities of mice. Golgi staining and immunohistochemical staining revealed that blockage of the β2-adrenergic receptor by ICI treatment decreased the number of dendritic branches, and ICI treatment in AD-TG mice decreased the expression of hippocampal synaptophysin and synapsin 1. Western blot assay results showed that the blockage of β2-adrenergic receptor increased amyloid-β accumulation by downregulating hippocampal α-secretase activity and increasing the phosphorylation of amyloid precursor protein. These findings suggest that blocking the β2-adrenergic receptor inhibits dendrite ramification of hippocampal neurons in a mouse model of AD. PMID:29089997

Alpha1-adrenergic receptor blockade in the VTA modulates fear memories and stress responses.

PubMed

Solecki, Wojciech B; Szklarczyk, Klaudia; Klasa, Adam; Pradel, Kamil; Dobrzański, Grzegorz; Przewłocki, Ryszard

2017-08-01

Activity of the ventral tegmental area (VTA) and its terminals has been implicated in the Pavlovian associative learning of both stressful and rewarding stimuli. However, the role of the VTA noradrenergic signaling in fear responses remains unclear. We aimed to examine how alpha 1 -adrenergic receptor (α 1 -AR) signaling in the VTA affects conditioned fear. The role of α 1 -AR was assessed using the micro-infusions into the VTA of the selective antagonists (0.1-1µg/0.5µl prazosin and 1µg/0.5µl terazosin) in acquisition and expression of fear memory. In addition, we performed control experiments with α 1 -AR blockade in the mammillary bodies (MB) - a brain region with α 1 -AR expression adjacent to the VTA. Intra-VTA but not intra-MB α 1 -AR blockade prevented formation and retrieval of fear memories. Importantly, local administration of α 1 -AR antagonists did not influence footshock sensitivity, locomotion or anxiety-like behaviors. Similarly, α 1 -AR blockade in the VTA had no effects on negative affect measured as number of 22kHz ultrasonic vocalizations during fear conditioning training. We propose that noradrenergic signaling in the VTA via α 1 -AR regulates formation and retrieval of fear memories but not other behavioral responses to stressful environmental stimuli. It enhances the encoding of environmental stimuli by the VTA to form and retrieve conditioned fear memories and to predict future behavioral outcomes. Our results provide novel insight into the role of the VTA α 1 -AR signaling in the regulation of stress responsiveness and fear memory. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

Modulation of haloperidol-induced patterns of the transcription factor Nur77 and Nor-1 expression by serotonergic and adrenergic drugs in the mouse brain

PubMed Central

Maheux, Jérôme; Vuillier, Laura; Mahfouz, Mylène; Rouillard, Claude; Lévesque, Daniel

2015-01-01

Different patterns of expression of the transcription factors of Nur77 and Nor-1 are induced following acute administration of typical and atypical antipsychotic drugs. The pharmacological profile of atypical antipsychotics suggests that serotonergic and/or adrenergic receptors might contribute to these reported differences. In order to test this possibility, we examined the abilities of serotonin 5-HT1A and 5-HT2A/2C, and α1- and α2-adrenergic receptor drugs to modify the pattern of Nur77 (NR4A1) and Nor-1 (NR4A3) mRNA expression induced by haloperidol. Various groups of mice were treated with either saline, DOI, a 5-HT2A/2C agonist, MDL11939, a 5-HT2A antagonist, 8-OH-DPAT, a 5-HT1A agonist, prazosin, an α1-adrenergic antagonist and idazoxan, an α2-adrenergic antagonist, alone or in combination with haloperidol. The 5-HT2A/2C agonist DOI alone significantly increased Nur77 expression in the medial striatum and nucleus accumbens. DOI reduced Nor-1 expression, while MDL11939 increased the expression of this transcript in the cortex. Prazosin reduced Nur77 expression in the dorsal striatum and nucleus accumbens. Interestingly, 8-OH-DPAT and MDL11939 partially prevented haloperidol-induced Nur77 up-regulation, while MDL11939 completely abolished Nor-1 expression in the striatum. In addition, MDL11939 decreased haloperidol-induced Nur77 and Nor-1 mRNA levels in the ventral tegmental area. On the contrary, idazoxan (α2 antagonist) consistently potentiated haloperidol-induced Nur77, but not Nor-1 mRNA levels in the striatum, whereas prazosin (α1 antagonist) remained without effect. Taken together, these results show the ability of a 5-HT1A agonist or a 5-HT2A antagonist to reduce haloperidol-induced Nur77 and Nor-1 striatal expression, suggesting that these serotonin receptor subtypes participate in the differential pattern of gene expression induced by typical and atypical antipsychotic drugs. PMID:21524335

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

PubMed

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

2016-06-15

Aiming to discover dual-acting β2 adrenergic/dopamine D2 receptor ligands, a structure-guided approach for the evolution of GPCR agonists that address multiple targets was elaborated. Starting from GPCR crystal structures, we describe the design, synthesis and biological investigation of a defined set of compounds leading to the identification of the benzoxazinone (R)-3, which shows agonist properties at the adrenergic β2 receptor and substantial G protein-promoted activation at the D2 receptor. This directed approach yielded molecular probes with tuned dual activity. The congener desOH-3 devoid of the benzylic hydroxyl function was shown to be a β2 adrenergic antagonist/D2 receptor agonist with Ki values in the low nanomolar range. The compounds may serve as a promising starting point for the investigation and treatment of neurological disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Drugs in development for Parkinson's disease.

PubMed

Johnston, Tom H; Brotchie, Jonathan M

2004-07-01

Pharmacological treatment of Parkinson's disease (PD) is entering a new and exciting era. Real promise now exists for the clinical application of a large range of molecules in development that will combat different aspects and stages of the condition. These include methyl- and ethyl-esterified forms of L-dopa (etilevodopa and melevodopa), inhibitors of enzymes such as monoamine oxidase type-B (eg, rasagiline), catechol-O-methyl transferase (eg, BIA-3202) and the monoamine re-uptake mechanism (eg, brasofensine). In addition, a range of full and partial dopamine agonists (eg, sumanirole, piribedil and BP-897) and their new formulations, for example, patch delivery systems (eg, rotigotine) are being developed. We also highlight non-dopaminergic treatments that will have wide ranging applications in the treatment of PD and L-dopa-induced dyskinesia. These include alpha2 adrenergic receptor antagonists (eg, fipamezole), adenosine A2A receptor antagonists (eg, istradefylline), AMPA receptor antagonists (eg, talampanel), neuronal synchronization modulators (eg, levetiracetam) and agents that interact with serotonergic systems such as 5-hydroxytryptamine (5-HT)1A agonists (eg, sarizotan) and 5-HT2A antagonists (eg, quetiapine). Lastly, we examine a growing number of neuroprotective agents that seek to halt or even reverse disease progression. These include anti-apoptotic kinase inhibitors (eg, CEP-1347), modulators of mitochondrial function (eg, creatine), growth factors (eg, leteprinim), neuroimmunophilins (eg, V-10367), estrogens (eg, MITO-4509), c-synuclein oligomerization inhibitors (eg, PAN-408) and sonic hedgehog ligands.

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

PubMed

Selvage, Dan

2012-06-01

Alcohol activates the hypothalamic-pituitary-adrenal (HPA) axis through its actions in both the periphery and the central nervous system (CNS). The studies presented here were designed to test the CNS-specific noradrenergic mechanisms by which alcohol stimulates HPA activity in the male rat. We used an experimental paradigm in which a small, nontoxic amount (5 μl) of alcohol was slowly microinfused intracerebroventricularly (icv). Alcohol was administered icv to animals with lesions of the locus coeruleus (LC) or in animals pretreated with α- or β-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). As expected, icv alcohol stimulated ACTH secretion from the pituitary and Fos expression in the paraventricular nucleus of the hypothalamus (PVN). Bilateral electrolytic LC 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 α-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 α-1 adrenergic receptor antagonist, modestly raised basal ACTH levels and blocked the icv alcohol-induced secretion of this hormone. These results indicate that the LC and norepinephrine 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 identified. Copyright © 2012 by the Research Society on Alcoholism.

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

DTIC Science & Technology

2014-10-01

TAF ) were isolated to determine if α2−AR activation directly modulates collagen microstructure. 15. SUBJECT TERMS Alpha2-adrenergic receptors, breast...group. 15 3) Significant results/key outcomes: Here we demonstrate the isolation of tumor associated fibroblasts ( TAF ) from 4T1 tumors. The goal...of these experiments was to determine the optimal conditions and appropriate markers for isolation of TAF and to optimize yield and purity of the

Neuroendocrine abnormalities in hypothalamic amenorrhea: spectrum, stability, and response to neurotransmitter modulation.

PubMed

Perkins, R B; Hall, J E; Martin, K A

1999-06-01

To characterize the neuroendocrine patterns of abnormal GnRH secretion in hypothalamic amenorrhea (HA), 49 women with primary and secondary HA underwent frequent sampling of LH in a total of 72 baseline studies over 12-24 h. A subset of women participated in more than one study to address 1) the variability of LH pulse patterns over time; and 2) the impact of modulating opioid, dopaminergic, and adrenergic tone on LH secretory patterns. The frequency and amplitude of LH secretion was compared with that seen in the early follicular phase (EFP) of normally cycling women. The spectrum of abnormalities of LH pulses was 8% apulsatile, 27% low frequency/low amplitude, 8% low amplitude/normal frequency, 43% low frequency/normal amplitude, 14% normal frequency/normal amplitude. Of patients studied overnight, 45% demonstrated a pubertal pattern of augmented LH secretion during sleep. Of patients studied repeatedly, 75% demonstrated at least 2 different patterns of LH secretion, and 33% reverted at least once to a normal pattern of secretion. An increase in LH pulse frequency was seen in 12 of 15 subjects in response to naloxone (opioid receptor antagonist). Clonidine (alpha-2 adrenergic agonist) was associated with a decrease in mean LH in 3 of 3 subjects. An increase in LH pulse frequency was seen in 4 of 8 subjects in response to metoclopramide (dopamine receptor antagonist), but the response was not statistically significant. Baseline abnormalities in LH secretion did not appear to influence response to neurotransmitter modulation. 1) HA represents a spectrum of disordered GnRH secretion that can vary over time; 2) LH pulse patterns at baseline do not appear to influence the ability to respond to neurotransmitter modulation; 3) Opioid and adrenergic tone appear to influence the hypothalamic GnRH pulse generator in some individuals with HA.

[Role of rostral ventrolateral medulla in the pressor response to intraventricular (4th) injection of substance P].

PubMed

Zhang, X H; Ni, H

1998-04-01

Experiments were done in rabbits anaesthetized with urethane and immobilized under artificial respiration. It was found that substance P (SP, 0.8 ng/kg dissolved in 100 microliters artificial cerebro-spinal fluid, CSF) injected into the 4th ventricle induced either a rise or a drop of pulmonary arterial pressure (PAP) with predominated pressor response. In addition, a rise in carotid arterial pressure (CAP) and reduction in heart rate (HR) were also observed, whereas no significant alteration in PAP, CAP and HR was observed. Microinjection of SP receptor antagonist [D-Pro2, D-Phe7, D-Trp9]--SP (5-10 ng dissolved in 0.5 microliter CSF) or phentolamine (2-3 micrograms dissolved in 0.5 microliter CSF) into the bilateral rostral ventrolateral medulla (rVLM) prior to intraventricular injection of SP could block the SP-induced pressor responses in pulmonary and carotid arteries, while microinjection of SP receptor antagonist or phentolamine into bilateral caudal ventrolateral medulla (cVLM) at the same dosage had no effect. The results show that SP-induced pulmonary and carotid pressor responses may be mediated through SP-receptor and alpha-adrenergic receptors in the rostral ventro-lateral medulla (rVLM).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1989-06-01

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

Inhibition of excitatory non-adrenergic non-cholinergic bronchoconstriction in guinea-pig airways in vitro by activation of an atypical 5-HT receptor.

PubMed Central

Ward, J. K.; Fox, A. J.; Barnes, P. J.; Belvisi, M. G.

1994-01-01

1. The effect of 5-hydroxytryptamine (5-HT) was studied on excitatory neurally mediated non-adrenergic non-cholinergic (NANC) contractions evoked by electrical field stimulation (EFS) in guinea-pig isolated bronchi. 2. 5-HT (0.1-100 microM) produced a concentration-dependent inhibition of the excitatory NANC response with 50.9 +/- 5.0% (n = 5, P < 0.01) inhibition at 100 microM. This inhibition was not significantly affected by the 5-HT2 antagonist, ketanserin (1 microM) when inhibitions (+/- ketanserin) at each concentration of 5-HT were compared by unpaired t tests; however, this concentration appeared to produce a leftward shift (approximately 10 fold) of the 5-HT concentration-inhibition curve. Ketanserin (1 microM) was effective in blocking bronchoconstriction evoked by activation of 5-HT2A receptors on airway smooth muscle. In the presence of ketanserin (1 microM) 5-HT (100 microM) evoked an inhibition of 57.4 +/- 5.9% (n = 5, P < 0.01) with an EC50 of 0.57 microM. 3. Inhibition evoked by 5-HT (0.1-100 microM) was unaffected by the alpha-adrenoceptor antagonist phentolamine (1 microM), the beta 2-adrenoceptor antagonist, ICI 118551 (0.1 microM), the 5-HT1A/B antagonist, cyanopindolol (1 microM) or the 5-HT3/4 antagonist, ICS 205-930 (1 microM). 4. Methiothepin (0.1 microM) produced an insurmountable inhibition of the effect of 5-HT (0.1-100 microM), reducing the maximum inhibition produced by 5-HT (100 microM) to 30.2 +/- 5.0% (n = 5, P < 0.001) and suggesting a non-competitive antagonism. Methiothepin inhibited the effect of 5-HT (10 microM) in a concentration-dependent manner with an IC50 of 81 nM.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7518294

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

PubMed Central

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

2014-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1981-03-01

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

COMBINED USE OF α-ADRENERGIC AND MUSCARINIC ANTAGONISTS FOR THE TREATMENT OF VOIDING DYSFUNCTION

PubMed Central

RUGGIERI, MICHAEL R.; BRAVERMAN, ALAN S.; PONTARI, MICHEL A.

2012-01-01

Purpose We provide an overview of the medical literature supporting the combined use of muscarinic and α-adrenergic antagonist therapy for the treatment of voiding dysfunction. Materials and Methods The MEDLINE database (1966 to 2004) of the United States National Library of Medicine was searched for pertinent studies. Results Although the mechanism of action of α-adrenergic antagonist therapy for voiding dysfunction has traditionally been assumed to be relaxation of the periurethral, prostatic and bladder neck smooth muscle, substantial evidence supports action at extraprostatic sites involved in micturition, including the bladder dome smooth muscle, peripheral ganglia, spinal cord and brain. Likewise the mechanism of action of anticholinergic therapy has been traditionally assumed to be inhibition of the M3 muscarinic receptor subtypes that mediate normal bladder contractions. However, M2 receptor mediates hypertrophied bladder contractions and there is evidence for an M2 component to the suprasacral control of voiding. Conclusions Based on the physiology of α-adrenergic and muscarinic receptors the inhibition of each one would be expected to be more beneficial than that of either alone because they would work on 2 components of detrusor function. Patients who would likely benefit from this combination therapy are men with lower urinary tract symptoms, women with urgency/frequency syndrome (overactive bladder), patients with uninhibited bladder contractions due to neurogenic bladder, and patients with pelvic pain and voiding symptoms, ie interstitial cystitis and chronic prostatitis/chronic pelvic pain syndrome. PMID:16217275

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. Copyright © 2011. Published by Elsevier Ireland Ltd.

Adrenergic receptors in human fetal liver membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 ofmore » 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.« less

Antidepressant activity of the adenosine A2A receptor antagonist, istradefylline (KW-6002) on learned helplessness in rats.

PubMed

Yamada, Koji; Kobayashi, Minoru; Shiozaki, Shizuo; Ohta, Teruko; Mori, Akihisa; Jenner, Peter; Kanda, Tomoyuki

2014-07-01

Istradefylline, an adenosine A2A receptor antagonist, improves motor function in animal models of Parkinson's disease (PD) and in patients with PD. In addition, some A2A antagonists exert antidepressant-like activity in rodent models of depression, such as the forced swim and the tail suspension tests. We have investigated the effect of istradefylline on depression-like behaviors using the rat learned helplessness (LH) model. Acute, as well as chronic, oral administration of istradefylline significantly improved the inescapable shock (IES)-induced escape deficit with a degree of efficacy comparable to chronic treatment with the tricyclic antidepressant desipramine and the selective serotonin (5-HT) reuptake inhibitor, fluoxetine. Both the A1/A2A receptor nonspecific antagonist theophylline and the moderately selective antagonist CGS15943, but not the A1 selective antagonist DPCPX, ameliorated the IES-induced escape deficit. The enhancement of escape response by istradefylline was reversed by a local injection of the A2A specific agonist CGS21680 either into the nucleus accumbens, the caudate-putamen, or the paraventricular nucleus of the hypothalamus, but not by the A1 specific agonist R-PIA into the nucleus accumbens. Moreover, neither the 5-HT2A/2C receptor antagonist methysergide or the adrenergic α 2 antagonist yohimbine, nor the β-adrenergic antagonist propranolol, affected the improvement of escape response induced by istradefylline. Istradefylline exerts antidepressant-like effects via modulation of A2A receptor activity which is independent of monoaminergic transmission in the brain. Istradefylline may represent a novel treatment option for depression in PD as well as for the motor symptoms.

Enhanced Y1-receptor-mediated vasoconstrictive action of neuropeptide Y (NPY) in superior mesenteric arteries in portal hypertension.

PubMed

Wiest, Reiner; Jurzik, Lars; Moleda, Lukas; Froh, Matthias; Schnabl, Bernd; von Hörsten, Stephan; Schölmerich, Juergen; Straub, Rainer H

2006-03-01

Vascular hyporeactivity to catecholamines contributes to arterial vasodilation and hemodynamic dysregulation in portal hypertension. Neuropeptide Y (NPY) is a sympathetic neurotransmitter facilitating adrenergic vasoconstriction via Y1-receptors on the vascular smooth muscle. Therefore, we investigated its role for vascular reactivity in the superior mesenteric artery (SMA) of portal vein ligated (PVL) and sham operated rats. In vitro perfused SMA vascular beds of rats were tested for the cumulative dose-response to NPY dependent on the presence and level of alpha1-adrenergic vascular tone (methoxamine MT: 0.3-10 microM). Moreover, the effect of NPY (50 nM) on vascular responsiveness to alpha1-adrenergic stimulation (MT: 0.3-300 microM) was evaluated. Y1-receptor function was tested by Y1-selective inhibition using BIBP-3226 (1 microM). NPY dose-dependently and endothelium-independently enhanced MT-pre-constriction in SMA. This potentiation was increasingly effective with increasing adrenergic pre-stimulation and being more pronounced in PVL rats as compared to sham rats at high MT concentrations. NPY enhanced vascular contractility only in PVL rats correcting the adrenergic vascular hyporeactivity. Y1-receptor inhibition completely abolished NPY-evoked vasoconstrictive effects. NPY endothelium-independently potentiates adrenergic vasoconstriction via Y1-receptors being more pronounced in portal hypertension improving mesenteric vascular contractility and thereby correcting the splanchnic vascular hyporeactivity. This makes NPY a superior vasoconstrictor counterbalancing arterial vasodilation in portal hypertension.

Betaxolol, a selective β1-adrenergic receptor antagonist, diminishes anxiety-like behavior during early withdrawal from chronic cocaine administration in rats

PubMed Central

Rudoy, C.A.; Van Bockstaele, E.J.

2007-01-01

Background Anxiety has been indicated as one of the main symptoms of the cocaine withdrawal syndrome in human addicts and severe anxiety during withdrawal may potentially contribute to relapse. As alterations in noradrenergic transmission in limbic areas underlie withdrawal symptomatology for many drugs of abuse, the present study sought to determine the effect of cocaine withdrawal on β-adrenergic receptor (β1 and β2) expression in the amygdala. Methods Male Sprague Dawley rats were administered intraperitoneal (i.p.) injections of cocaine (20 mg/kg) once daily for 14 days. Two days following the last cocaine injection, amygdala brain regions were micro-dissected and processed for Western blot analysis. Results showed that β1–adrenergic receptor, but not β2–adrenergic receptor expression was significantly increased in amygdala extracts of cocaine-withdrawn animals as compared to controls. This finding motivated further studies aimed at determining whether treatment with betaxolol, a highly selective β1–adrenergic receptor antagonist, could ameliorate cocaine withdrawal-induced anxiety. In these studies, betaxolol (5 mg/kg via i.p. injection) was administered at 24 and then 44 hours following the final chronic cocaine administration. Anxiety-like behavior was evaluated using the elevated plus maze test approximately 2 hours following the last betaxolol injection. Following behavioral testing, betaxolol effects on β1-adrenergic receptor protein expression were examined by Western blotting in amygdala extracts from rats undergoing cocaine withdrawal. Results Animals treated with betaxolol during cocaine withdrawal exhibited a significant attenuation of anxiety-like behavior characterized by increased time spent in the open arms and increased entries into the open arms compared to animals treated with only saline during cocaine withdrawal. In contrast, betaxolol did not produce anxiolytic-like effects in control animals treated chronically with saline. Furthermore, treatment with betaxolol during early cocaine withdrawal significantly decreased β1-adrenergic receptor protein expression in the amygdala to levels comparable to those of control animals. Conclusions The present findings suggest that the anxiolytic-like effect of betaxolol on cocaine-induced anxiety may be related to its effect on amygdalar β1-adrenergic receptors that are up-regulated during early phases of drug withdrawal. These data support the efficacy of betaxolol as a potential effective pharmacotherapy in treating cocaine withdrawal-induced anxiety during early phases of abstinence. PMID:17513029

Betaxolol, a selective beta(1)-adrenergic receptor antagonist, diminishes anxiety-like behavior during early withdrawal from chronic cocaine administration in rats.

PubMed

Rudoy, C A; Van Bockstaele, E J

2007-06-30

Anxiety has been indicated as one of the main symptoms of the cocaine withdrawal syndrome in human addicts and severe anxiety during withdrawal may potentially contribute to relapse. As alterations in noradrenergic transmission in limbic areas underlie withdrawal symptomatology for many drugs of abuse, the present study sought to determine the effect of cocaine withdrawal on beta-adrenergic receptor (beta(1) and beta(2)) expression in the amygdala. Male Sprague Dawley rats were administered intraperitoneal (i.p.) injections of cocaine (20 mg/kg) once daily for 14 days. Two days following the last cocaine injection, amygdala brain regions were micro-dissected and processed for Western blot analysis. Results showed that beta(1)-adrenergic receptor, but not beta(2)-adrenergic receptor expression was significantly increased in amygdala extracts of cocaine-withdrawn animals as compared to controls. This finding motivated further studies aimed at determining whether treatment with betaxolol, a highly selective beta(1)-adrenergic receptor antagonist, could ameliorate cocaine withdrawal-induced anxiety. In these studies, betaxolol (5 mg/kg via i.p. injection) was administered at 24 and then 44 h following the final chronic cocaine administration. Anxiety-like behavior was evaluated using the elevated plus maze test approximately 2 h following the last betaxolol injection. Following behavioral testing, betaxolol effects on beta(1)-adrenergic receptor protein expression were examined by Western blotting in amygdala extracts from rats undergoing cocaine withdrawal. Animals treated with betaxolol during cocaine withdrawal exhibited a significant attenuation of anxiety-like behavior characterized by increased time spent in the open arms and increased entries into the open arms compared to animals treated with only saline during cocaine withdrawal. In contrast, betaxolol did not produce anxiolytic-like effects in control animals treated chronically with saline. Furthermore, treatment with betaxolol during early cocaine withdrawal significantly decreased beta(1)-adrenergic receptor protein expression in the amygdala to levels comparable to those of control animals. The present findings suggest that the anxiolytic-like effect of betaxolol on cocaine-induced anxiety may be related to its effect on amygdalar beta(1)-adrenergic receptors that are up-regulated during early phases of drug withdrawal. These data support the efficacy of betaxolol as a potential effective pharmacotherapy in treating cocaine withdrawal-induced anxiety during early phases of abstinence.

Pharmacology of the hypothermic response to 5-HT1A receptor activation in humans.

PubMed

Lesch, K P; Poten, B; Söhnle, K; Schulte, H M

1990-01-01

The selective 5-HT1A receptor ligand ipsapirone (IPS) caused dose-related hypothermia in humans. The response was attenuated by the nonselective 5-HT1/2 receptor antagonist metergoline and was completely antagonized by the nonselective beta-adrenoceptor antagonist pindolol, which interacts stereoselectively with the 5-HT1A receptor. The selective beta 1-adrenergic antagonist betaxolol had no effect. The findings indicate that IPS-induced hypothermia specifically involves activation of (presynaptic) 5-HT1A receptors. Therefore, the hypothermic response to IPS may provide a convenient in vivo paradigma to assess the function of the presynaptic 5-HT receptor in affective disorders and its involvement in the effects of psychotropic drugs.

Ganglionic adrenergic action modulates ovarian steroids and nitric oxide in prepubertal rat.

PubMed

Delgado, Silvia Marcela; Casais, Marilina; Sosa, Zulema; Rastrilla, Ana María

2006-08-01

Both peripheral innervation and nitric oxide (NO) participate in ovarian steroidogenesis. The purpose of this work was to analyse the ganglionic adrenergic influence on the ovarian release of steroids and NO and the possible steroids/NO relationship. The experiments were carried out in the ex vivo coeliac ganglion-superior ovarian nerve (SON)-ovary system of prepubertal rats. The coeliac ganglion-SON-ovary system was incubated in Krebs Ringer-bicarbonate buffer in presence of adrenergic agents in the ganglionic compartment. The accumulation of progesterone, androstenedione, oestradiol and NO in the ovarian incubation liquid was measured. Norepinephrine in coeliac ganglion inhibited the liberation of progesterone and increased androstenedione, oestradiol and NO in ovary. The addition of alpha and beta adrenergic antagonists also showed different responses in the liberation of the substances mentioned before, which, from a physiological point of view, reveals the presence of adrenergic receptors in coeliac ganglion. In relation to propranolol, it does not revert the effect of noradrenaline on the liberation of progesterone, which leads us to think that it might also have a "per se" effect on the ganglion, responsible for the ovarian response observed for progesterone. Finally, we can conclude that the ganglionic adrenergic action via SON participates on the regulation of the prepubertal ovary in one of two ways: either increasing the NO, a gaseous neurotransmitter with cytostatic characteristics, to favour the immature follicles to remain dormant or increasing the liberation of androstenedione and oestradiol, the steroids necessary for the beginning of the near first estral cycle.

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.

Salt sensitivity in normotensives with family history of hypertension: studies of membrane transport, intracellular electrolytes and alpha 2-adrenergic receptors.

PubMed

Skrabal, F; Gruber, G; Meister, B; Ledochowski, M; Doll, P; Lang, F; Cerny, E

1985-12-01

Using long-term automatic blood pressure recording it has previously been shown that subjects with family history of hypertension show a minute fall of blood pressure during sodium restriction, which is reversible by high sodium intake. Thus normotensives with hypertensive antecedents as a group are salt-sensitive, whereas normotensives without heredity of hypertension as a group are salt-resistant. The present study compares intracellular sodium, potassium and calcium, sodium pump activity, NaK-cotransport of red blood cells and density and affinity of alpha 2-adrenergic receptors of platelets in normotensive subjects classified according to family history of hypertension and according to 'salt sensitivity' and 'salt resistance'. Neither the family history of hypertension nor salt sensitivity correlated with intracellular sodium, potassium, calcium, Na-pump activity and NaK-cotransport. Alpha 2-adrenergic density was higher in salt-sensitive than in salt-resistant subjects (P < 0.05) but similar in subjects with a positive and negative family history of hypertension. However, alpha 2-adrenergic receptor density decreased significantly during 2 weeks of moderate salt restriction from 169.6 +/- 34.2 to 142.6 +/- 30.8 (P < 0.01, paired t-test), which may explain the decreased pressor response to infused noradrenaline observed in a previous study during moderate salt restriction. It is concluded that in humans there is no association of genetic predisposition of hypertension or of salt sensitivity to an alteration of sodium pump activity, NaK-cotransport, intracellular sodium and calcium. Alpha 2-receptor density of platelets deserves further study as a possible predictor of salt sensitivity in normotensives.

CgA1AR-1 acts as an alpha-1 adrenergic receptor in oyster Crassostrea gigas mediating both cellular and humoral immune response.

PubMed

Liu, Zhaoqun; Zhou, Zhi; Wang, Lingling; Qiu, Limei; Zhang, Huan; Wang, Hao; Song, Linsheng

2016-11-01

We have now cloned an alpha-1 adrenergic receptor (A1AR) from the cDNA library of oyster Crassostrea gigas, designating as CgA1AR-1. The full length of CgA1AR-1 was 1149 bp and it encodes a protein of 382 amino acids containing a 7 transmembrane domain, whose putative topology was similar to the A1ARs in higher organisms and shared similarity of 19% with mammalian A1ARs according to the phylogenic analysis. After cell transfection of CgA1AR-1 into HEK293T cells and the incubation with its specific agonist norepinephrine (NE), the concentration of second messenger Ca 2+ increased significantly (p < 0.05). But, this increasing of Ca 2+ could be inhibited by adding A1AR antagonist DOX. Tissue distribution assays using qRT-PCR suggested that CgA1AR-1 mRNA was ubiquitously expressed in all the major tissues of oyster. LPS stimulation could induce the up-regulation of CgA1AR-1 mRNA in haemocytes from 12 h to 24 h post stimulation. Moreover, the blocking of CgA1AR-1 by DOX before LPS stimulation affected the mRNA expression of oyster TNF (CGI_10005109 and CGI_10006440) in haemocytes, resulting in the rise of haemocyte phagocytic rate and apoptosis index. In addition to cellular immunity, CgA1AR-1 was also involved in humoral immunity of oyster. Inhibition of CgA1AR-1 with DOX could repress the up-regulation of LZY and SOD activities caused by LPS stimulation. These results suggested that CgA1AR-1 acted as an α-1 adrenergic receptor in cetacholaminergic neuroendocrine-immune network mediating both cellular and humoral immune response. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of [D-Phe6] bombesin (6-13) methylester, a bombesin receptor antagonist, towards bombesin-induced contractions in the guinea-pig and rat isolated urinary bladder.

PubMed

Maggi, C A; Coy, D H; Giuliani, S

1992-08-01

1. The effect of [D-Phe6] bombesin (6-13) methylester (OMe), a newly developed potent antagonist of bombesin receptors, has been investigated against bombesin-induced contractions of the guinea-pig and rat isolated urinary bladder. 2. Bombesin (0.1 nM-10 microM) produced a concentration-dependent contraction of the guinea-pig isolated bladder which approached the same maximum response as KCl (80 mM). The response to bombesin was antagonized in a competitive manner (rightward shift of the concentration-response curve without depression of the maximal response) by [D-Phe6] bombesin (6-13) OMe (0.3-10 microM). Degree of antagonism was concentration-dependent between 0.3 and 3 microM (dose ratios = 2.4, 9 and 39 in the presence of 0.3, 1, 3 microM of the antagonist). However, a larger concentration (10 microM) of the antagonist was not more effective (dose ratio = 36) than 3 microM. 3. Neither the action of bombesin nor the activity of the antagonist was influenced by peptidase inhibitors (bestatin, captopril and thiorphan 3 microM each) or by atropine, indomethacin, chlorpheniramine and desensitization of P2x purinoceptors by alpha, beta methylene ATP. 4. The bombesin antagonist was ineffective against contraction of the guinea-pig urinary bladder produced by the NK-1 tachykinin receptor-selective agonist, [Sar9] substance P sulphone. The action of the NK-1 receptor agonist was antagonized by L 668, 169 (3 microM), a cyclic peptide tachykinin antagonist. L 668, 169 had no effect toward bombesin-induced contraction. 5. The bombesin antagonist (1-10 microM) had no effect against the non-adrenergic non-cholinergic response of the guinea-pig isolated urinary bladder to electrical field stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations of myocardial and vascular adrenergic receptor-mediated responses in Escherichia coli-induced septic shock in the rat.

PubMed

Boillot, A; Massol, J; Maupoil, V; Grelier, R; Capellier, G; Berthelot, A; Barale, F

1996-08-01

To investigate responsiveness to exogenous catecholamines in rat bacteremic shock by studying both myocardial and vascular functional parameters; to determine in the same study the relationship of these parameters with other relevant biological parameters of the adrenergic pathway, such as myocardial beta-adrenergic receptors and cyclic adenosine monophosphate (cAMP); and to indirectly approach the roles of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide. Experimental, comparative study. Laboratory in a university hospital. Male Sprague-Dawley rats, weighing 270 to 320 g. Intravenous injection of live Escherichia coli DH5 alpha (2 x 10(10) organisms/kg) or saline (0.6 mL) and comparison of the two groups. Mean arterial pressure and heart rate (HR) were recorded, and circulating TNF-alpha concentrations were measured, during the first 3 hrs after E. coli administration. Myocardial and vascular functional parameters were obtained, respectively, from Langendorff-perfused hearts and isolated aortic rings. Adrenergic biochemical parameters (catecholamines, density and affinity of beta-receptors, and isoproterenol-stimulated myocardial cAMP) were determined 3 hrs after E. coli injection. Mean arterial pressure decreased within 5 to 60 mins after bacteria injection and returned to basal levels in the last 2 hrs; HR was unchanged. Serum TNF-alpha concentrations peaked at 120 mins (7333 +/- 672 pg/mL) and were still increased at 3 hrs. Plasma concentrations of epinephrine and norepinephrine were significantly (p < .05) increased. Baseline values for differential left ventricular pressure and coronary flow were significantly (p < .0001, p < .001, respectively) reduced; HR remained unchanged. Isoproterenol induced a similar increase in differential left ventricular pressure and in HR. There was no decrease in the functional myocardial response to adrenergic stimulation. beta-adrenergic receptors were similar in density and in affinity in the two groups. Isoproterenol-stimulated myocardial cAMP was significantly (p < .01) reduced compared with the control group. In aortic rings, bacteria administration significantly (p < .01) shifted the dose-response curve to norepinephrine to the right, both in the presence and absence of endothelium. NG-monomethyl-L-arginine significantly increased the contractions to attain the control level: p < .001 in presence of endothelium; p < .05 in absence of endothelium. In ex vivo experiments, 3 hrs after E. coli injection, vascular responsiveness was sharply decreased. This impaired response was improved by inhibition of nitric oxide. The heart, nevertheless, was still able to modulate its inotropic and chronotropic response to isoproterenol, even though an impaired beta-adrenergic-receptor stimulation of cAMP was already present.

Evidence that (-)-7-hydroxy-4'-dimethylheptyl-cannabidiol activates a non-CB(1), non-CB(2), non-TRPV1 target in the mouse vas deferens.

PubMed

Pertwee, Roger G; Thomas, Adèle; Stevenson, Lesley A; Maor, Yehoshua; Mechoulam, Raphael

2005-06-01

Previous experiments showed that R-(+)-WIN55212-induced inhibition of electrically-evoked contractions of mouse vasa deferentia could be antagonized by cannabidiol in a manner that appeared to be competitive but not to involve direct competition for established cannabinoid receptors. We have now discovered that (-)-7-hydroxy-4'-dimethylheptyl-cannabidiol (7-OH-DMH-CBD) inhibits electrically-evoked contractions of the vas deferens (EC(50)=13.3 nM). This it appeared to do by acting on prejunctional neurones as 100 nM 7-OH-DMH-CBD did not attenuate contractile responses to phenylephrine or beta,gamma-methylene-ATP. Although 7-OH-DMH-CBD was antagonized by SR141716A, it was less susceptible to antagonism by this CB(1) receptor antagonist than R-(+)-WIN55212. 7-OH-DMH-CBD was also antagonized by cannabidiol (1 microM; apparent K(B)=222.2 nM) but not by the CB(2) receptor antagonist, SR144528 (32 nM), or by naloxone (300 nM), ruthenium red (1 microM) or capsazepine (10 microM). Yohimbine (100 nM) enhanced the ability of 7-OH-DMH-CBD to inhibit electrically-evoked contractions. R-(+)-WIN55212 was also potentiated by 100 nM yohimbine, possibly reflecting ongoing sequestration of G(i/o) proteins from CB(1) receptors by alpha(2)-adrenoceptors. Our results suggest that 7-OH-DMH-CBD may activate a neuronal target in the vas deferens that is not a CB(1), CB(2), TRPV1, opioid or alpha(2)-adrenergic receptor but do not exclude the possibility that it also activates CB(1) receptors.

Alpha-2 adrenergic stimulation triggers Achilles tenocyte hypercellularity: Comparison between two model systems

PubMed Central

Backman, L J; Andersson, G; Fong, G; Alfredson, H; Scott, A; Danielson, P

2013-01-01

The histopathology of tendons with painful tendinopathy is often tendinosis, a fibrosis-like condition of unclear pathogenesis characterized by tissue changes including hypercellularity. The primary tendon cells (tenocytes) have been shown to express adrenoreceptors (mainly alpha-2A) as well as markers of catecholamine production, particularly in tendinosis. It is known that adrenergic stimulation can induce proliferation in other cells. The present study investigated the effects of an exogenously administered alpha-2 adrenergic agonist in an established in vivo Achilles tendinosis model (rabbit) and also in an in vitro human tendon cell culture model. The catecholamine producing enzyme tyrosine hydroxylase and the alpha-2A-adrenoreceptor (α2A AR) were expressed by tenocytes, and alpha-2 adrenergic stimulation had a proliferative effect on these cells, in both models. The proliferation was inhibited by administration of an α2A AR antagonist, and the in vitro model further showed that the proliferative alpha-2A effect was mediated via a mitogenic cell signaling pathway involving phosphorylation of extracellular-signal-regulated kinases 1 and 2. The results indicate that catecholamines produced by tenocytes in tendinosis might contribute to the proliferative nature of the pathology through stimulation of the α2A AR, pointing to a novel target for future therapies. The study furthermore shows that animal models are not necessarily required for all aspects of this research. PMID:22292987

Conformational thermostabilization of the β1-adrenergic receptor in a detergent-resistant form

PubMed Central

Serrano-Vega, Maria J.; Magnani, Francesca; Shibata, Yoko; Tate, Christopher G.

2008-01-01

There are ≈350 non-odorant G protein-coupled receptors (GPCRs) encoded by the human genome, many of which are predicted to be potential therapeutic targets, but there are only two structures available to represent the whole of the family. We hypothesized that improving the detergent stability of these receptors and simultaneously locking them into one preferred conformation will greatly improve the chances of crystallization. We developed a generic strategy for the isolation of detergent-solubilized thermostable mutants of a GPCR, the β1-adrenergic receptor. The most stable mutant receptor, βAR-m23, contained six point mutations that led to an apparent Tm 21°C higher than the native protein, and, in the presence of bound antagonist, βAR-m23 was as stable as bovine rhodopsin. In addition, βAR-m23 was significantly more stable in a wide range of detergents ideal for crystallization and was preferentially in an antagonist conformation in the absence of ligand. PMID:18192400

Pentadecapeptide BPC 157 interactions with adrenergic and dopaminergic systems in mucosal protection in stress.

PubMed

Sikirić, P; Mazul, B; Seiwerth, S; Grabarević, Z; Rucman, R; Petek, M; Jagić, V; Turković, B; Rotkvić, I; Mise, S; Zoricić, I; Jurina, L; Konjevoda, P; Hanzevacki, M; Gjurasin, M; Separović, J; Ljubanović, D; Artuković, B; Bratulić, M; Tisljar, M; Miklić, P; Sumajstorcić, J

1997-03-01

Since superior protection against different gastrointestinal and liver lesions and antiinflammatory and analgesic activities were noted for pentadecapeptide BPC (an essential fragment of an organoprotective gastric juice protein named BPC), the beneficial mechanism of BPC 157 and its likely interactions with other systems were studied. Hence its beneficial effects would be abolished by adrenal gland medullectomy, the influence of different agents affecting alpha, beta, and dopamine receptors on BPC 157 gastroprotection in 48 h restraint stress was further investigated. Animals were pretreated (1 hr before stress) with saline (controls) or BPC 157 (dissolved in saline) (10 microg or 10 ng/kg body wt intraperitoneally or intragastrically) applied either alone to establish basal conditions or, when manipulating the adrenergic or dopaminergic system, a simultaneous administration was carried out with various agents with specific effects on adrenergic or dopaminergic receptors [given in milligrams per kilogram intraperitoneally except for atenolol, which was given subcutaneously] phentolamine (10.0), prazosin (0.5), yohimbine (5.0), clonidine (0.1) (alpha-adrenergic domain), propranolol (1.0), atenolol (20.0) (beta-adrenergic domain), domperidone (5.0), and haloperidol (5.0) (peripheral/central dopamine system). Alternatively, agents stimulating adrenergic or dopaminergic systems--adrenaline (5.0) or bromocriptine (10.0)--were applied. A strong protection, noted following intragastric or intraperitoneal administration of BPC 157, was fully abolished by coadministration of phentolamine, clonidine, and haloperidol, and consistently not affected by prazosin, yohimbine, or domperidone. Atenolol abolished only intraperitoneal BPC 157 protection, whereas propranolol affected specifically intragastric BPC 157 protection. Interestingly, the severe course of lesion development obtained in basal conditions, unlike BPC 157 gastroprotection, was not influenced by the application of these agents. In other experiments, when adrenaline and bromocriptine were given simultaneously, a strong reduction of lesion development was noted. However, when applied separately, only adrenaline, not bromocriptine, has a protective effect. Thus, a complex protective interaction with both alpha-adrenergic (eg, catecholamine release) and dopaminergic (central) systems could be suggested for both intragastric and intraperitoneal BPC 157 administration. The involvement of beta-receptor stimulation in BPC 157 gastroprotection appears to be related to the route of BPC 157 administration. The demonstration that a combined stimulation of adrenergic and dopaminergic systems by simultaneous prophylactic application of adrenaline (alpha- and beta-receptor stimulant) and bromocriptine (dopamine receptor agonist) may significantly reduce restraint stress lesions development provides insight for further research on the beneficial mechanism of BPC 157.

Alpha-1-Adrenergic Receptors in Heart Failure: The Adaptive Arm of the Cardiac Response to Chronic Catecholamine Stimulation

PubMed Central

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

2013-01-01

Alpha-1-adrenergic receptors are G-protein coupled receptors (GPCRs) activated by catecholamines. The alpha-1A and alpha-1B subtypes are expressed in mouse and human myocardium, whereas the alpha-1D protein is found only in coronary arteries. There are far fewer alpha-1-ARs than beta-ARs in the non-failing heart, but their abundance is maintained or increased in the setting of heart failure, which is characterized by pronounced chronic elevation of catecholamines and b□eta-AR dysfunction. Decades of evidence from gain- and loss-of-function studies in isolated cardiac myocytes and numerous animal models demonstrate important adaptive functions for cardiac alpha-1-ARs, to include physiological hypertrophy, positive inotropy, ischemic preconditioning, and protection from cell death. Clinical trial data indicate that blocking alpha-1-ARs is associated with incident heart failure in patients with hypertension. Collectively, these findings suggest that alpha-1-AR activation might mitigate the well-recognized toxic effects of beta-ARs in the hyperadrenergic setting of chronic heart failure. Thus, exogenous cardioselective activation of alpha-1-ARs might represent a novel and viable approach to the treatment of heart failure. PMID:24145181

Neuropeptide AF induces anxiety-like and antidepressant-like behavior in mice.

PubMed

Palotai, Miklós; Telegdy, Gyula; Tanaka, Masaru; Bagosi, Zsolt; Jászberényi, Miklós

2014-11-01

Little is known about the action of neuropeptide AF (NPAF) on anxiety and depression. Only our previous study provides evidence that NPAF induces anxiety-like behavior in rats. Therefore, the aim of the present study was to investigate the action of NPAF on depression-like behavior and the underlying neurotransmissions in mice. In order to determine whether there are species differences between rats and mice, we have investigated the action of NPAF on anxiety-like behavior in mice as well. A modified forced swimming test (mFST) and an elevated plus maze test (EPMT) were used to investigate the depression and anxiety-related behaviors, respectively. Mice were treated with NPAF 30min prior to the tests. In the mFST, the animals were pretreated with a non-selective muscarinic acetylcholine receptor antagonist, atropine, a non-selective 5-HT2 serotonergic receptor antagonist, cyproheptadine, a mixed 5-HT1/5-HT2 serotonergic receptor antagonist, methysergide, a D2/D3/D4 dopamine receptor antagonist, haloperidol, a α1/α2β-adrenergic receptor antagonist, prazosin or a non-selective β-adrenergic receptor antagonist, propranolol 30min before the NPAF administration. In the mFST, NPAF decreased the immobility time and increased the climbing and swimming times. This action was reversed completely by methysergide and partially by atropine, whereas cyproheptadine, haloperidol, prazosin and propranolol were ineffective. In the EPMT, NPAF decreased the time spent in the arms (open/open+closed). Our results demonstrate that NPAF induces anti-depressant-like behavior in mice, which is mediated, at least in part, through 5HT2-serotonergic and muscarinic cholinergic neurotransmissions. In addition, the NPAF-induced anxiety is species-independent, since it develops also in mice. Copyright © 2014 Elsevier B.V. All rights reserved.

Control of yeast mating signal transduction by a mammalian. beta. sub 2 -adrenergic receptor and G sub s. alpha. subunit

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, K.; Caron, M.G.; Lefkowitz, R.J.

1990-10-05

To facilitate functional and mechanistic studies of receptor-G protein interactions by expression of the human {beta}{sub 2}-adrenergic receptor (h{beta}-AR) has been expressed in Saccharomyces cerevisiae. This was achieved by placing a modified h{beta}-AR gene under control of the galactose-inducible GAL1 promoter. After induction by galactose, functional h{beta}-AR was expressed at a concentration several hundred times as great as that found in any human tissue. As determined from competitive ligand binding experiments, h{beta}-AR expressed in yeast displayed characteristic affinities, specificity, and stereoselectivity. Partial activation of the yeast pheromone response pathway by {beta}-adrenergic receptor agonists was achieved in cells coexpressing h{beta}-AR andmore » a mammalian G protein (G{sub s}) {alpha} subunit - demonstrating that these components can couple to each other and to downstream effectors when expressed in yeast. This in vivo reconstitution system provides a new approach for examining ligand binding and G protein coupling to cell surface receptors.« less

β1- and β2-adrenergic receptor stimulation differ in their effects on PGC-1α and atrogin-1/MAFbx gene expression in chick skeletal muscle.

PubMed

Shimamoto, Saki; Ijiri, Daichi; Kawaguchi, Mana; Nakashima, Kazuki; Tada, Osamu; Inoue, Hiroki; Ohtsuka, Akira

2017-09-01

Adrenaline changes expression of the genes encoding peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α), which is known as a regulator of muscle size, and atrogin-1/muscle atrophy F-box (MAFbx), which is a muscle-specific ubiquitin ligase. However, the subtype of β-adrenergic receptor (β-AR) involved in regulating these genes in skeletal muscle is not yet well defined. In this study, the effects of intraperitoneal injection of adrenaline and three β 1-3 -AR selective agonists on chick skeletal muscle metabolism were examined, to evaluate the functions of β-AR subtypes. Adrenaline decreased atrogin-1/MAFbx mRNA levels accompanied by an increase in PGC-1α mRNA and protein levels. However, among the three selective agonists, only the β 1 -AR agonist, dobutamine, increased PGC-1α mRNA and protein levels, while the β 2 -AR agonist, clenbuterol, suppressed atrogin-1/MAFbx mRNA levels. In addition, preinjection of the β 1 -AR antagonist, acebutolol, and the β 2 -AR antagonist, butoxamine, inhibited the adrenaline-induced increase in PGC-1α mRNA levels and the decrease in atrogin-1/MAFbx mRNA levels, respectively. Compared with adrenaline administration, the β 3 -AR agonist, BRL37344, decreased PGC-1α mRNA levels and increased atrogin-1/MAFbx mRNA levels. These results suggest that, in chick skeletal muscle, PGC-1α is induced via the β 1 -AR, while atrogin-1/MAFbx is suppressed via the β 2 -AR. Copyright © 2017. Published by Elsevier Inc.

Apparent loss-of-function mutant GPCRs revealed as constitutively desensitized receptors.

PubMed

Wilbanks, Alyson M; Laporte, Stéphane A; Bohn, Laura M; Barak, Larry S; Caron, Marc G

2002-10-08

The DRY motif is a triplet amino acid sequence (aspartic acid, arginine, and tyrosine) that is highly conserved in G protein-coupled receptors (GPCRs). Recently, we have shown that a molecular determinant for nephrogenic diabetes insipidus, the vasopressin receptor with a substitution at the DRY motif arginine (V2R R137H), is a constitutively desensitized receptor that is unable to couple to G proteins due to its constitutive association with beta-arrestin [Barak, L. S. (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 93-98]. Additionally, the mutant receptors are localized in endocytic vesicles, identical to wild-type receptors stimulated with agonist. In this study, we asked whether the constitutively desensitized phenotype observed in the V2R R137H represents a general paradigm that may be extended to other GPCRs. We show that arginine substitutions in the DRY motifs of the alpha(1B) adrenergic receptor (alpha(1B)-AR) and angiotensin II type 1A receptor (AT(1A)R) result in receptors that are uncoupled from G proteins, associated with beta-arrestins, and found localized in endocytic vesicles rather than at the plasma membrane in the absence of agonists. The localization of the alpha(1B)-ARs and AT(1A)Rs with arginine substitutions can be restored to the plasma membrane by either using selective antagonists or preventing the endocytosis of the beta-arrestin-receptor complexes. These results indicate that the arginine residue of the DRY motif is essential for preserving the localization of the inactive receptor complex. Furthermore, constitutive desensitization may underlie some loss-of-function receptor phenotypes and represent an unappreciated mechanism of hormonal resistance.

Spinal α2-adrenergic and muscarinic receptors and the NO release cascade mediate supraspinally produced effectiveness of gabapentin at decreasing mechanical hypersensitivity in mice after partial nerve injury

PubMed Central

Takasu, Keiko; Honda, Motoko; Ono, Hideki; Tanabe, Mitsuo

2006-01-01

After partial nerve injury, the central analgesic effect of systemically administered gabapentin is mediated by both supraspinal and spinal actions. We further evaluate the mechanisms related to the supraspinally mediated analgesic actions of gabapentin involving the descending noradrenergic system. Intracerebroventricularly (i.c.v.) administered gabapentin (100 μg) decreased thermal and mechanical hypersensitivity in a murine chronic pain model that was prepared by partial ligation of the sciatic nerve. These effects were abolished by intrathecal (i.t.) injection of either yohimbine (3 μg) or idazoxan (3 μg), α2-adrenergic receptor antagonists. Pretreatment with atropine (0.3 mg kg−1, i.p. or 0.1 μg, i.t.), a muscarinic receptor antagonist, completely suppressed the effect of i.c.v.-injected gabapentin on mechanical hypersensitivity, whereas its effect on thermal hypersensitivity remained unchanged. Similar effects were obtained with pirenzepine (0.1 μg, i.t.), a selective M1-muscarinic receptor antagonist, but not with methoctramine (0.1 and 0.3 μg, i.t.), a selective M2-muscarinic receptor antagonist. The cholinesterase inhibitor neostigmine (0.3 ng, i.t.) potentiated only the analgesic effect of i.c.v. gabapentin on mechanical hypersensitivity, confirming spinal acetylcholine release downstream of the supraspinal action of gabapentin. Moreover, the effect of i.c.v. gabapentin on mechanical but not thermal hypersensitivity was reduced by i.t. injection of L-NAME (3 μg) or L-NMMA (10 μg), both of which are nitric oxide (NO) synthase inhibitors. Systemically administered naloxone (10 mg kg−1, i.p.), an opioid receptor antagonist, failed to suppress the analgesic actions of i.c.v. gabapentin, indicating that opioid receptors are not involved in activation of the descending noradrenergic system by gabapentin. Thus, the supraspinally mediated effect of gabapentin on mechanical hypersensitivity involves activation of spinal α2-adrenergic receptors followed by muscarinic receptors (most likely M1) and the NO cascade. In contrast, the effect of supraspinal gabapentin on thermal hypersensitivity is independent of the spinal cholinergic–NO system. PMID:16582934

Topiramate via NMDA, AMPA/kainate, GABAA and Alpha2 receptors and by modulation of CREB/BDNF and Akt/GSK3 signaling pathway exerts neuroprotective effects against methylphenidate-induced neurotoxicity in rats.

PubMed

Motaghinejad, Majid; Motevalian, Manijeh; Fatima, Sulail; Beiranvand, Tabassom; Mozaffari, Shiva

2017-11-01

Chronic abuse of methylphenidate (MPH) often causes neuronal cell death. Topiramate (TPM) carries neuroprotective effects, but its exact mechanism of action remains unclear. In the present study, the role of various doses of TPM and its possible mechanisms, receptors and signaling pathways involved against MPH-induced hippocampal neurodegeneration were evaluated in vivo. Thus, domoic acid (DOM) was used as AMPA/kainate receptor agonist, bicuculline (BIC) as GABA A receptor antagonist, ketamine (KET) as NMDA receptor antagonist, yohimbine (YOH) as α 2 adrenergic receptor antagonist and haloperidol (HAL) was used as dopamine D 2 receptor antagonist. Open field test (OFT) was used to investigate the disturbances in motor activity. Hippocampal neurodegenerative parameters were evaluated. Protein expressions of CREB/BDNF and Akt/GSK3 signaling pathways were also evaluated. Cresyl violet staining was performed to show and confirm the changes in the shape of the cells. TPM (70 and 100 mg/kg) reduced MPH-induced rise in lipid peroxidation, oxidized form of glutathione (GSSG), IL-1β and TNF-α levels, Bax expression and motor activity disturbances. In addition, TPM treatment increased Bcl-2 expression, the level of reduced form of glutathione (GSH) and the levels and activities of superoxide dismutase, glutathione peroxidase and glutathione reductase enzymes. TPM also inhibited MPH-induced hippocampal degeneration. Pretreatment of animals with DOM, BIC, KET and YOH inhibited TPM-induced neuroprotection and increased oxidative stress, neuroinflammation, neuroapoptosis and neurodegeneration while reducing CREB, BDNF and Akt protein expressions. Also pretreatment with DOM, BIC, KET and YOH inhibited TPM-induced decreases in GSK3. It can be concluded that the mentioned receptors by modulation of CREB/BDNF and Akt/GSK3 pathways, are involved in neuroprotection of TPM against MPH-induced neurodegeneration.

Characterization of adrenergic receptors of the cat iris and nictitating membrane.

PubMed

Koss, M C; Hey, J A; Gherezghiher, T

1990-01-01

Graded pupillary dilations and nictitating membrane (NM) contractions were elicited in anesthetized cats by electrical stimulation of the preganglionic sympathetic nerve or by i.a. administration of norepinephrine (NE) or phenylephrine into the carotid artery. Pupil and NM responses were measured simultaneously from the same side. Alpha-adrenoceptor antagonists were administered intravenously. All of the alpha 1-adrenoceptor blockers tested produced a dose-related reduction of NM responses to both neural and agonist activation; the potency rank order was prazosin greater than WB-4101 greater than phentolamine greater than phenoxybenzamine (PBZ). In contrast, responses of the iris dilator were antagonized only by WB-4101 and PBZ. The iris was almost totally refractory to doses of prazosin and phentolamine that blocked NM responses by more than 75% of control. Neither alpha 2- nor beta-adrenoceptor antagonism produced significant inhibition of neural or agonist activation of either organ (with the exception of high doses of yohimbine on the NM). These results suggest that the postjunctional adrenoceptors of the NM are exclusively of the alpha 1-adrenoceptor subtype. In contrast, those of the iris dilator muscle cannot be easily classified pharmacologically as either alpha 1 or alpha 2-adrenoceptors.

Inhibition of excitatory non-adrenergic non-cholinergic bronchoconstriction in guinea-pig airways in vitro by activation of an atypical 5-HT receptor.

PubMed

Ward, J K; Fox, A J; Barnes, P J; Belvisi, M G

1994-04-01

1. The effect of 5-hydroxytryptamine (5-HT) was studied on excitatory neurally mediated non-adrenergic non-cholinergic (NANC) contractions evoked by electrical field stimulation (EFS) in guinea-pig isolated bronchi. 2. 5-HT (0.1-100 microM) produced a concentration-dependent inhibition of the excitatory NANC response with 50.9 +/- 5.0% (n = 5, P < 0.01) inhibition at 100 microM. This inhibition was not significantly affected by the 5-HT2 antagonist, ketanserin (1 microM) when inhibitions (+/- ketanserin) at each concentration of 5-HT were compared by unpaired t tests; however, this concentration appeared to produce a leftward shift (approximately 10 fold) of the 5-HT concentration-inhibition curve. Ketanserin (1 microM) was effective in blocking bronchoconstriction evoked by activation of 5-HT2A receptors on airway smooth muscle. In the presence of ketanserin (1 microM) 5-HT (100 microM) evoked an inhibition of 57.4 +/- 5.9% (n = 5, P < 0.01) with an EC50 of 0.57 microM. 3. Inhibition evoked by 5-HT (0.1-100 microM) was unaffected by the alpha-adrenoceptor antagonist phentolamine (1 microM), the beta 2-adrenoceptor antagonist, ICI 118551 (0.1 microM), the 5-HT1A/B antagonist, cyanopindolol (1 microM) or the 5-HT3/4 antagonist, ICS 205-930 (1 microM). 4. Methiothepin (0.1 microM) produced an insurmountable inhibition of the effect of 5-HT (0.1-100 microM), reducing the maximum inhibition produced by 5-HT (100 microM) to 30.2 +/- 5.0% (n = 5, P < 0.001) and suggesting a non-competitive antagonism. Methiothepin inhibited the effect of 5-HT (10 microM) in a concentration-dependent manner with an IC50 of 81 nM. 5. Selective 5-HT receptor agonists were also tested on excitatory NANC responses. 5-Carboxamidotryptamine (5-CT, 0.1-100 MicroM) was the most potent, producing a concentration-dependent inhibition with an EC50 of 0.13 MicroM. Calculation of approximate IC25 values (concentration of the agonist required to give a 25% inhibition of the excitatory NANC response) gave a rank order of potency 5-CT > 5-HT> > 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) >alpha-methyl-5-hydroxytryptamine (alpha-Me-5HT). Sumatriptan, 5-methoxytryptamine (5-MeOT) and 2-methyl-5-hydroxytryptamine (2-Me-5HT) were essentially inactive with IC25> 100 MicroM.6. 5-HT (10 microM) did not significantly affect contractile responses to exogenously applied substance P(1 nM-10 Microm).7. The effect of 5-HT was unchanged after incubation with the nitric oxide (NO) synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME, 100 Microm). However, pretreatment with charybdotoxin (ChTX,0.1-30 nM), a blocker of the large conductance Ca2+-activated K+channel (K+ca), produced a concentration-dependent inhibition of the effect of 5-HT (10 MicroM).8. 5-HT evokes a concentration-dependent inhibition of e-NANC bronchoconstriction in guinea-pig isolated bronchi but does not affect cumulative concentration-dependent contractile responses to substance P, suggesting that inhibition is via a prejunctional receptor. Effects of selective antagonists and agonists suggest that an atypical 5-HT receptor mediates this inhibition. The inhibitory effect of 5-HT does not involve the production of NO, but may involve the opening a ChTX-sensitive K+ca channel.These data suggest that an atypical 5-HT receptor inhibits the release of neuropeptides from sensory C fibres and may act as other inhibitory neuromodulators via the opening of a common K'channel.

Bladder pain induced by prolonged peripheral alpha 1A adrenoceptor stimulation involves the enhancement of transient receptor potential vanilloid 1 activity and an increase of urothelial adenosine triphosphate release.

PubMed

Matos, R; Cordeiro, J M; Coelho, A; Ferreira, S; Silva, C; Igawa, Y; Cruz, F; Charrua, A

2016-12-01

Pathophysiological mechanisms of chronic visceral pain (CVP) are unknown. This study explores the association between the sympathetic system and bladder nociceptors activity by testing the effect of a prolonged adrenergic stimulation on transient receptor potential vanilloid 1 (TRPV1) activity and on urothelial adenosine triphosphate (ATP) release. Female Wistar rats received saline, phenylephrine (PHE), PHE + silodosin, PHE + naftopidil or PHE + prazosin. TRPV1 knockout and wild-type mice received saline or PHE. Visceral pain behaviour tests were performed before and after treatment. Cystometry was performed, during saline and capsaicin infusion. Fos immunoreactivity was assessed in L6 spinal cord segment. Human urothelial ATP release induced by mechanical and thermal stimulation was evaluated. Subcutaneous, but not intrathecal, PHE administration induced pain, which was reversed by silodosin, a selective alpha 1A adrenoceptor antagonist, but not by naftopidil, a relatively selective antagonist for alpha 1D adrenoceptor. Silodosin also reversed PHE-induced bladder hyperactivity and L6 spinal cord Fos expression. Thus, in subsequent experiments, only silodosin was used. Wild-type, but not TRPV1 knockout, mice exhibited phenylephrine-induced pain. Capsaicin induced a greater increase in voiding contractions in PHE-treated rats than in control animals, and silodosin reversed this effect. When treated with PHE, ATP release from human urothelial cells was enhanced either by mechanical stimulation or by lowering the thermal threshold of urothelial TRPV1, which becomes abnormally responsive at body temperature. This study suggests that the activation of peripheral alpha 1A adrenoceptors induces CVP, probably through its interaction with TRPV1 and ATP release. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Dopamine acting at D1-like, D2-like and α1-adrenergic receptors differentially modulates theta and gamma oscillatory activity in primary motor cortex.

PubMed

Özkan, Mazhar; Johnson, Nicholas W; Sehirli, Umit S; Woodhall, Gavin L; Stanford, Ian M

2017-01-01

The loss of dopamine (DA) in Parkinson's is accompanied by the emergence of exaggerated theta and beta frequency neuronal oscillatory activity in the primary motor cortex (M1) and basal ganglia. DA replacement therapy or deep brain stimulation reduces the power of these oscillations and this is coincident with an improvement in motor performance implying a causal relationship. Here we provide in vitro evidence for the differential modulation of theta and gamma activity in M1 by DA acting at receptors exhibiting conventional and non-conventional DA pharmacology. Recording local field potentials in deep layer V of rat M1, co-application of carbachol (CCh, 5 μM) and kainic acid (KA, 150 nM) elicited simultaneous oscillations at a frequency of 6.49 ± 0.18 Hz (theta, n = 84) and 34.97 ± 0.39 Hz (gamma, n = 84). Bath application of DA resulted in a decrease in gamma power with no change in theta power. However, application of either the D1-like receptor agonist SKF38393 or the D2-like agonist quinpirole increased the power of both theta and gamma suggesting that the DA-mediated inhibition of oscillatory power is by action at other sites other than classical DA receptors. Application of amphetamine, which promotes endogenous amine neurotransmitter release, or the adrenergic α1-selective agonist phenylephrine mimicked the action of DA and reduced gamma power, a result unaffected by prior co-application of D1 and D2 receptor antagonists SCH23390 and sulpiride. Finally, application of the α1-adrenergic receptor antagonist prazosin blocked the action of DA on gamma power suggestive of interaction between α1 and DA receptors. These results show that DA mediates complex actions acting at dopamine D1-like and D2-like receptors, α1 adrenergic receptors and possibly DA/α1 heteromultimeric receptors to differentially modulate theta and gamma activity in M1.

Dopamine induces inhibitory effects on the circular muscle contractility of mouse distal colon via D1- and D2-like receptors.

PubMed

Auteri, Michelangelo; Zizzo, Maria Grazia; Amato, Antonella; Serio, Rosa

2016-08-01

Dopamine (DA) acts as gut motility modulator, via D1- and D2-like receptors, but its effective role is far from being clear. Since alterations of the dopaminergic system could lead to gastrointestinal dysfunctions, a characterization of the enteric dopaminergic system is mandatory. In this study, we investigated the role of DA and D1- and D2-like receptors in the contractility of the circular muscle of mouse distal colon by organ-bath technique. DA caused relaxation in carbachol-precontracted circular muscle strips, sensitive to domperidone, D2-like receptor antagonist, and mimicked by bromocriptine, D2-like receptor agonist. 7-Chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH-23390), D1-like receptor antagonist, neural toxins, L-NAME (nitric oxide (NO) synthase inhibitor), 2'-deoxy-N 6 -methyl adenosine 3',5'-diphosphate diammonium salt (MRS 2179), purinergic P2Y1 antagonist, or adrenergic antagonists were ineffective. DA also reduced the amplitude of neurally evoked cholinergic contractions. The effect was mimicked by (±)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrobromide (SKF-38393), D1-like receptor agonist and antagonized by SCH-23390, MRS 2179, or L-NAME. Western blotting analysis determined the expression of DA receptor proteins in mouse distal colon. Notably, SCH-23390 per se induced an increase in amplitude of spontaneous and neurally evoked cholinergic contractions, unaffected by neural blockers, L-NAME, MRS 2179, muscarinic, adrenergic, or D2-like receptor antagonists. Indeed, SCH-23390-induced effects were antagonized by an adenylyl cyclase blocker. In conclusion, DA inhibits colonic motility in mice via D2- and D1-like receptors, the latter reducing acetylcholine release from enteric neurons, involving nitrergic and purinergic systems. Whether constitutively active D1-like receptors, linked to adenylyl cyclase pathway, are involved in a tonic inhibitory control of colonic contractility is questioned.

Pertussis toxin-sensitive G-protein mediates the alpha 2-adrenergic receptor inhibition of melatonin release in photoreceptive chick pineal cell cultures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratt, B.L.; Takahashi, J.S.

The avian pineal gland is a photoreceptive organ that has been shown to contain postjunctional alpha 2-adrenoceptors that inhibit melatonin synthesis and/or release upon receptor activation. Physiological response and (32P)ADP ribosylation experiments were performed to investigate whether pertussis toxin-sensitive guanine nucleotide-binding proteins (G-proteins) were involved in the transduction of the alpha 2-adrenergic signal. For physiological response studies, the effects of pertussis toxin on melatonin release in dissociated cell cultures exposed to norepinephrine were assessed. Pertussis toxin blocked alpha 2-adrenergic receptor-mediated inhibition in a dose-dependent manner. Pertussis toxin-induced blockade appeared to be noncompetitive. One and 10 ng/ml doses of pertussis toxinmore » partially blocked and a 100 ng/ml dose completely blocked norepinephrine-induced inhibition. Pertussis toxin-catalyzed (32P)ADP ribosylation of G-proteins in chick pineal cell membranes was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Membranes were prepared from cells that had been pretreated with 0, 1, 10, or 100 ng/ml pertussis toxin. In the absence of pertussis toxin pretreatment, two major proteins of 40K and 41K mol wt (Mr) were labeled by (32P)NAD. Pertussis toxin pretreatment of pineal cells abolished (32P) radiolabeling of the 40K Mr G-protein in a dose-dependent manner. The norepinephrine-induced inhibition of both cAMP efflux and melatonin release, as assessed by RIA of medium samples collected before membrane preparation, was also blocked in a dose-dependent manner by pertussis toxin. Collectively, these results suggest that a pertussis toxin-sensitive 40K Mr G-protein labeled by (32P)NAD may be functionally associated with alpha 2-adrenergic signal transduction in chick pineal cells.« less

Insulin induces alpha1B-adrenergic receptor phosphorylation and desensitization.

PubMed

García-Sáinz, J Adolfo; Romero-Avila, M Teresa; Molina-Muñoz, Tzindilú; Medina, Luz del Carmen

2004-09-03

The ability of insulin to induce alpha1B-adrenoceptor phosphorylation and desensitization was tested in two model systems: rat-1 cells that stably express alpha1B-adrenoceptors, through transfection, and endogenously express insulin receptors and DDT1 MF2 cells that endogenously express both receptors. Insulin induced concentration-dependent increases in the phosphorylation state of the adrenergic receptors in the two models with similar EC50 values (0.5-2 nM). The effect was rapid in the two systems but it was sustained in rat-1 cells and transient in DDT1 MF2 cells. In both cell lines, the insulin-mediated phosphorylation of alpha1B-adrenoceptors was blocked by wortmannin and LY 294002, and by staurosporine and bisindolylmaleimide I, indicating that the effect involved phosphoinositide 3-kinase and protein kinase C activities. The adrenoceptor phosphorylation induced by insulin was associated to desensitization as evidences by a diminished elevation of intracellular calcium in response to noradrenaline. Inhibitors of phosphoinositide 3-kinase and protein kinase C blocked the functional desensitization induced by insulin.

Alpha 1 adrenergic receptor mediated polyphosphoinositide breakdown in DDT1-MF2 cells. Lack of evidence of desensitization after prolonged exposure to epinephrine.

PubMed

Rosenbaum, J S; Azhar, S; Hoffman, B B

1987-12-15

The DDT1-MF2 cell line is a transformed smooth muscle cell line which is known to possess both alpha 1 and beta 2 adrenergic receptors. We have utilized these cells to compare the effects of epinephrine pretreatment on the functional capabilities of these two different adrenergic receptors. Pretreatment of the cells grown in suspension with 10(-7) M epinephrine for 6 hr resulted in desensitization of beta receptor stimulated cyclic AMP accumulation. The maximal response to isoproterenol was decreased to 46 +/- 6% of the value in controls (P less than 0.05); there was also a decrease in the sensitivity of the cells to isoproterenol (log EC50 = -6.65 +/- 0.22 vs -7.26 +/- 0.11 in controls, P less than 0.05). Also, there was a decrease in the number of beta receptors from 257 +/- 29 to 163 +/- 22 fmol/mg protein. In contrast, pretreatment with 10(-6) M epinephrine for 6 hr failed to induce a loss of sensitivity in the ability of the alpha 1 receptor agonist phenylephrine to stimulate inositol triphosphate accumulation (log EC50 = -5.59 +/- 0.18 vs -5.42 +/- 0.44 in control cells). A 2-fold increase in basal inositol monophosphate accumulation was observed after epinephrine pretreatment (P less than 0.05); however, there was no change in maximal phenylephrine-stimulated inositol monophosphate accumulation in these cells. There was a small decrease in the alpha 1 receptor number after epinephrine pretreatment (Bmax = 457 +/- 89 fmol/mg protein vs 540 +/- 94 in control cells, P less than 0.05). In contrast to epinephrine pretreatment, pretreatment of cells in suspension with 10(-7) M 12-O-tetradecanoylphorbol-13-acetate (TPA) for 15 min resulted in a nearly complete blunting in the ability of both norepinephrine and phenylephrine to stimulate inositol phosphate accumulation: after norepinephrine stimulation, 774 +/- 34 dpm in TPA-pretreated cells vs 2590 +/- 10 in control cells; inositol monophosphate accumulation after phenylephrine stimulation 576 +/- 25 dpm in TPA-pretreated cells vs 1660 +/- 27 in control cells. Basal levels of inositol monophosphate remained unchanged at 544 +/- 28 dpm vs 505 +/- 31 in TPA-pretreated cells compared to control cells. These data indicate that protein kinase C may exert a negative feedback control on the alpha 1 receptor in these cells and that direct activation of protein kinase C by phorbol esters may have a different effect on the alpha 1 adrenergic receptor system in DDT1-MF2 cells than does prolonged exposure to epinephrine.

Type-7 metabotropic glutamate receptors negatively regulate α1-adrenergic receptor signalling.

PubMed

Iacovelli, Luisa; Di Menna, Luisa; Peterlik, Daniel; Stangl, Christina; Orlando, Rosamaria; Molinaro, Gemma; De Blasi, Antonio; Bruno, Valeria; Battaglia, Giuseppe; Flor, Peter J; Uschold-Schmidt, Nicole; Nicoletti, Ferdinando

2017-02-01

We studied the interaction between mGlu7 and α 1 -adrenergic receptors in heterologous expression systems, brain slices, and living animals. L-2-Amino-4-phosphonobutanoate (L-AP4), and l-serine-O-phosphate (L-SOP), which activate group III mGlu receptors, restrained the stimulation of polyphosphoinositide (PI) hydrolysis induced by the α 1 -adrenergic receptor agonist, phenylephrine, in HEK 293 cells co-expressing α 1 -adrenergic and mGlu7 receptors. The inibitory action of L-AP4 was abrogated by (i) the mGlu7 receptor antagonist, XAP044; (ii) the C-terminal portion of type-2 G protein coupled receptor kinase; and (iii) the MAP kinase inhibitors, UO126 and PD98059. This suggests that the functional interaction between mGlu7 and α 1 -adrenergic receptors was mediated by the βγ-subunits of the G i protein and required the activation of the MAP kinase pathway. Remarkably, activation of neither mGlu2 nor mGlu4 receptors reduced α 1 -adrenergic receptor-mediated PI hydrolysis. In mouse cortical slices, both L-AP4 and L-SOP were able to attenuate norepinephrine- and phenylephrine-stimulated PI hydrolysis at concentrations consistent with the activation of mGlu7 receptors. L-AP4 failed to affect norepinephrine-stimulated PI hydrolysis in cortical slices from mGlu7 -/- mice, but retained its inhibitory activity in slices from mGlu4 -/- mice. At behavioural level, i.c.v. injection of phenylephrine produced antidepressant-like effects in the forced swim test. The action of phenylephrine was attenuated by L-SOP, which was inactive per se. Finally, both phenylephrine and L-SOP increased corticosterone levels in mice, but the increase was halved when the two drugs were administered in combination. Our data demonstrate that α 1 -adrenergic and mGlu7 receptors functionally interact and suggest that this interaction might be targeted in the treatment of stress-related disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cannabidiol, extracted from Cannabis sativa, selectively inhibits inflammatory hypermotility in mice.

PubMed

Capasso, R; Borrelli, F; Aviello, G; Romano, B; Scalisi, C; Capasso, F; Izzo, A A

2008-07-01

Cannabidiol is a Cannabis-derived non-psychotropic compound that exerts a plethora of pharmacological actions, including anti-inflammatory, neuroprotective and antitumour effects, with potential therapeutic interest. However, the actions of cannabidiol in the digestive tract are largely unexplored. In the present study, we investigated the effect of cannabidiol on intestinal motility in normal (control) mice and in mice with intestinal inflammation. Motility in vivo was measured by evaluating the distribution of an orally administered fluorescent marker along the small intestine; intestinal inflammation was induced by the irritant croton oil; contractility in vitro was evaluated by stimulating the isolated ileum, in an organ bath, with ACh. In vivo, cannabidiol did not affect motility in control mice, but normalized croton oil-induced hypermotility. The inhibitory effect of cannabidiol was counteracted by the cannabinoid CB1 receptor antagonist rimonabant, but not by the cannabinoid CB2 receptor antagonist SR144528 (N-[-1S-endo-1,3,3-trimethyl bicyclo [2.2.1] heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide), by the opioid receptor antagonist naloxone or by the alpha2-adrenergic antagonist yohimbine. Cannabidiol did not reduce motility in animals treated with the fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine, whereas loperamide was still effective. In vitro, cannabidiol inhibited ACh-induced contractions in the isolated ileum from both control and croton oil-treated mice. Cannabidiol selectively reduces croton oil-induced hypermotility in mice in vivo and this effect involves cannabinoid CB1 receptors and FAAH. In view of its low toxicity in humans, cannabidiol may represent a good candidate to normalize motility in patients with inflammatory bowel disease.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 Silasticmore » 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.« less

Treatment of developmental stress disorder: mind, body and brain - analysis and pharmacology coupled.

PubMed

McFadden, Joseph

2017-11-01

The schism between psychiatry, psychology and analysis, while long present, has widened even more in the past half-century with the advances in psychopharmacology. With the advances in electronic brain imaging, particularly in developmental and post-traumatic stress disorders, there has emerged both an understanding of brain changes resulting from severe, chronic stress and an ability to target brain chemistry in ways that can relieve clinical symptomatology. The use of alpha-1 adrenergic brain receptor antagonists decreases many of the manifestations of PTSD. Additionally, this paper discusses the ways in which dreaming, thinking and the analytic process are facilitated with this concomitant treatment and hypervigilence and hyper-arousal states are signficiantly decreased. © 2017, The Society of Analytical Psychology.

Memory trace reactivation and behavioral response during retrieval are differentially modulated by amygdalar glutamate receptors activity: interaction between amygdala and insular cortex

PubMed Central

Osorio-Gómez, Daniel; Guzmán-Ramos, Kioko

2017-01-01

The insular cortex (IC) is required for conditioned taste aversion (CTA) retrieval. However, it remains unknown which cortical neurotransmitters levels are modified upon CTA retrieval. Using in vivo microdialysis, we observed that there were clear elevations in extracellular glutamate, norepinephrine, and dopamine in and around the center of the gustatory zone of the IC during CTA retrieval. Additionally, it has been reported that the amygdala–IC interaction is highly involved in CTA memory establishment. Therefore, we evaluated the effects of infusions of an AMPA receptor antagonist (CNQX) and a NMDA receptor antagonist (APV) into the amygdala on CTA retrieval and IC neurotransmitter levels. Infusion of APV into the amygdala impaired glutamate augmentation within the IC, whereas dopamine and norepinephrine levels augmentation persisted and a reliable CTA expression was observed. Conversely, CNQX infusion into the amygdala impaired the aversion response, as well as norepinephrine and dopamine augmentations in the IC. Interestingly, CNQX infusion did not affect glutamate elevation in the IC. To evaluate the functional meaning of neurotransmitters elevations within the IC on CTA response, we infused specific antagonists for the AMPA, NMDA, D1, and β-adrenergic receptor before retrieval. Results showed that activation of AMPA, D1, and β-adrenergic receptors is necessary for CTA expression, whereas NMDA receptors are not involved in the aversion response. PMID:27980072

Norepinephrine infusion with and without alpha-adrenergic blockade by phentolamine increases salivary alpha amylase in healthy men.

PubMed

Kuebler, Ulrike; von Känel, Roland; Heimgartner, Nadja; Zuccarella-Hackl, Claudia; Stirnimann, Guido; Ehlert, Ulrike; Wirtz, Petra H

2014-11-01

Mental stress reliably induces increases in salivary alpha amylase (sAA), a suggested surrogate marker for sympathetic nervous system (SNS) reactivity. While stress-induced sAA increases correlate with norepinephrine (NE) secretion, a potential mediating role of noradrenergic mechanisms remains unclear. In this study, we investigated for the first time in humans whether a NE-stress-reactivity mimicking NE-infusion with and without alpha-adrenergic blockade by phentolamine would induce changes in sAA. In a single-blind placebo-controlled within-subjects design, 21 healthy men (29-66 years) took part in three different experimental trials varying in terms of substance infusion with a 1-min first infusion followed by a 15-min second infusion: saline-infusion (trial-1), NE-infusion (5 μg/min) without alpha-adrenergic blockade (trial-2), and with phentolamine-induced non-selective blockade of alpha1- and alpha2-adrenergic receptors (trial-3). Saliva samples were collected immediately before, during, and several times after substance infusion in addition to blood pressure and heart rate readings. Experimental trials significantly differed in sAA reactivity to substance-infusion (p=.001) with higher sAA reactivity following NE-infusion with (trial-3; p=.001) and without alpha-adrenergic-blockade (trial-2; p=.004) as compared to placebo-infusion (trial-1); sAA infusion reactivity did not differ between trial-2 and trial-3 (p=.29). Effective phentolamine application was verified by blood pressure and heart rate infusion reactivity. Salivary cortisol was not affected by NE, either with or without alpha-adrenergic-blockade. We found that NE-infusion stimulates sAA secretion, regardless of co-administered non-selective alpha-adrenergic blockade by phentolamine, suggesting that the mechanism underlying stress-induced sAA increases may involve NE. Copyright © 2014 Elsevier Ltd. All rights reserved.

Leptin decreases heart rate associated with increased ventricular repolarization via its receptor.

PubMed

Lin, Yen-Chang; Huang, Jianying; Hileman, Stan; Martin, Karen H; Hull, Robert; Davis, Mary; Yu, Han-Gang

2015-11-15

Leptin has been proposed to modulate cardiac electrical properties via β-adrenergic receptor activation. The presence of leptin receptors and adipocytes in myocardium raised a question as to whether leptin can directly modulate cardiac electrical properties such as heart rate and QT interval via its receptor. In this work, the role of local direct actions of leptin on heart rate and ventricular repolarization was investigated. We identified the protein expression of leptin receptors at cell surface of sinus node, atrial, and ventricular myocytes isolated from rat heart. Leptin at low doses (0.1-30 μg/kg) decreased resting heart rate; at high doses (150-300 μg/kg), leptin induced a biphasic effect (decrease and then increase) on heart rate. In the presence of high-dose propranolol (30 mg/kg), high-dose leptin only reduced heart rate and sometimes caused sinus pauses and ventricular tachycardia. The leptin-induced inhibition of resting heart rate was fully reversed by leptin antagonist. Leptin also increased heart rate-corrected QT interval (QTc), and leptin antagonist did not. In isolated ventricular myocytes, leptin (0.03-0.3 μg/ml) reversibly increased the action potential duration. These results supported our hypothesis that in addition to indirect pathway via sympathetic tone, leptin can directly decrease heart rate and increase QT interval via its receptor independent of β-adrenergic receptor stimulation. During inhibition of β-adrenergic receptor activity, high concentration of leptin in myocardium can cause deep bradycardia, prolonged QT interval, and ventricular arrhythmias. Copyright © 2015 the American Physiological Society.

Leptin decreases heart rate associated with increased ventricular repolarization via its receptor

PubMed Central

Lin, Yen-Chang; Huang, Jianying; Hileman, Stan; Martin, Karen H.; Hull, Robert; Davis, Mary

2015-01-01

Leptin has been proposed to modulate cardiac electrical properties via β-adrenergic receptor activation. The presence of leptin receptors and adipocytes in myocardium raised a question as to whether leptin can directly modulate cardiac electrical properties such as heart rate and QT interval via its receptor. In this work, the role of local direct actions of leptin on heart rate and ventricular repolarization was investigated. We identified the protein expression of leptin receptors at cell surface of sinus node, atrial, and ventricular myocytes isolated from rat heart. Leptin at low doses (0.1–30 μg/kg) decreased resting heart rate; at high doses (150–300 μg/kg), leptin induced a biphasic effect (decrease and then increase) on heart rate. In the presence of high-dose propranolol (30 mg/kg), high-dose leptin only reduced heart rate and sometimes caused sinus pauses and ventricular tachycardia. The leptin-induced inhibition of resting heart rate was fully reversed by leptin antagonist. Leptin also increased heart rate-corrected QT interval (QTc), and leptin antagonist did not. In isolated ventricular myocytes, leptin (0.03–0.3 μg/ml) reversibly increased the action potential duration. These results supported our hypothesis that in addition to indirect pathway via sympathetic tone, leptin can directly decrease heart rate and increase QT interval via its receptor independent of β-adrenergic receptor stimulation. During inhibition of β-adrenergic receptor activity, high concentration of leptin in myocardium can cause deep bradycardia, prolonged QT interval, and ventricular arrhythmias. PMID:26408544

Antihypertensive effect of alpha- and beta-adrenergic blockade in obese and lean hypertensive subjects.

PubMed

Wofford, M R; Anderson, D C; Brown, C A; Jones, D W; Miller, M E; Hall, J E

2001-07-01

The purpose of this study was to determine the contribution of the adrenergic system in mediating hypertension in obese and lean patients. Thirteen obese, hypertensive patients with a body mass index (BMI) > or =28 kg/m2 (obese) and nine lean patients with a BMI < or =25 kg/m2 (lean) were recruited. After a 1-week washout period, participants underwent daytime ambulatory blood pressure monitoring (ABPM). Participants were then treated with the alpha-adrenergic antagonist doxazosin, titrating to 4 mg QHS in 1 week. In the next week, the beta-adrenergic antagonist atenolol was added at an initial dose of 25 mg/day and titrated to 50 mg/day within 1 week. One month after the addition of atenolol, all patients underwent a second ABPM session. There were no differences between the obese and lean subjects in baseline systolic (SBP), diastolic (DBP), or mean arterial pressures (MAP) measured by office recording or ABPM. However, obese subjects had higher heart rates than lean subjects (87.5+/-2.4 v 76.8+/-4.9 beats/min). After 1 month of treatment with the adrenergic blockers, obese patients had a significantly lower SBP (130.0+/-2.5 v 138.9+/-2.1 mm Hg, P = .02) and MAP (99.6+/-2.3 v 107.0+/-1.5 mm Hg, P = .02) than lean patients. Obese patients also tended to have a lower DBP than lean patients (84.3+/-2.5 v 90.9+/-1.6 mm Hg, P = .057), but there was no significant difference in heart rate after 1 month of adrenergic blockade. These results indicate that blood pressure is more sensitive to adrenergic blockade in obese than in lean hypertensive patients and suggest that increased sympathetic activity may be an important factor in the maintenance of hypertension in obesity.

Multiple receptors coupled to phospholipase C gate long-term depression in visual cortex.

PubMed

Choi, Se-Young; Chang, Jeff; Jiang, Bin; Seol, Geun-Hee; Min, Sun-Seek; Han, Jung-Soo; Shin, Hee-Sup; Gallagher, Michela; Kirkwood, Alfredo

2005-12-07

Long-term depression (LTD) in sensory cortices depends on the activation of NMDA receptors. Here, we report that in visual cortical slices, the induction of LTD (but not long-term potentiation) also requires the activation of receptors coupled to the phospholipase C (PLC) pathway. Using immunolesions in combination with agonists and antagonists, we selectively manipulated the activation of alpha1 adrenergic, M1 muscarinic, and mGluR5 glutamatergic receptors. Inactivation of these PLC-coupled receptors prevents the induction of LTD, but only when the three receptors were inactivated together. LTD is fully restored by activating any one of them or by supplying intracellular D-myo-inositol-1,4,5-triphosphate (IP3). LTD was also impaired by intracellular application of PLC or IP3 receptor blockers, and it was absent in mice lacking PLCbeta1, the predominant PLC isoform in the forebrain. We propose that visual cortical LTD requires a minimum of PLC activity that can be supplied independently by at least three neurotransmitter systems. This essential requirement places PLC-linked receptors in a unique position to control the induction of LTD and provides a mechanism for gating visual cortical plasticity via extra-retinal inputs in the intact organism.

Αlpha-2 Adrenergic and Opioids Receptors Participation in Mice Gastroprotection of Abelmoschus esculentus Lectin.

PubMed

Ribeiro, Kátia A; Chaves, Hellíada V; Filho, Samuel Mateus Pereira; Pinto, Isabela Ribeiro; Monteiro, Dina Andressa Martins; Matos, Samuel Oliveira; Santi-Gadelha, Tatiane; Gadelha, Carlos Alberto de Almeida; Lacerda, José Thalles Jocelino Gomes de; Aguiar, Lissiana M V; Pereira, Karuza M A; Benevides, Norma M B; Pinto, Vicente de Paulo T; Filho, Gerardo Cristino; Bezerra, Mirna M; Silva, Antonio A R

2016-01-01

Lectins are a heterogeneous group of proteins and glycoproteins with potential role as therapeutic and diagnostic tools to combat various diseases, besides some functions on human organism. Abelmoschus esculentus (Okra), a horticultural plant of African origin, is cultivated in northeastern Brazil, and used for different medicinal purposes. This work is aimed to elucidate the action mechanisms of Abelmoschus esculentus lectin (AEL) gastro protective effect on gastropathy induced by ethanol. Fasted mice treated with Ethanol 99.9% (0.2 ml/animal, p.o.) received previously AEL (0.01, 0.1, 1.0, 10 or 50 mg/kg, i.v.), saline (5 ml/kg; i.v.) or ranitidine (80 mg/kg, p.o.) in four experimental series, in which pharmacological tools (yohimbine, naloxone, L-NAME or indomethacin), were administered with the purpose of make clear possible molecular action mechanisms. Mice were euthanized 30 min after ethanol challenge to verify the stomach damages. Establishment of gastric oxidative stress, tissue hemoglobin (Hb) content and microscopic features (H&E) were taken in order to characterize the AEL gastro protective effect. AEL (1 mg/kg) was capable of protect mucosa against ethanol damages in presence of two (L-NAME and indomethacin) of four antagonists/inhibitors used. The AEL effect was reversed by naloxone and yohimbine, showing the involvement of opioids and Αlpha-2 adrenergic receptors on gastric protective effect of this lectin. Evaluation of microscopic features, oxidative stress, and Hb levels pointed the protective effects of AEL. This activity seems to be mediated by alpha-2 adrenergic and opioid receptors activation. Nitric oxide or prostaglandins were not involved. AEL simultaneously showed antioxidant effect that is probably implicated in its intricate defensive mechanism of action.

Kinin B1 receptor antagonists containing alpha-methyl-L-phenylalanine: in vitro and in vivo antagonistic activities.

PubMed

Gobeil, F; Charland, S; Filteau, C; Perron, S I; Neugebauer, W; Regoli, D

1999-03-01

-To protect from metabolism and to improve potency of the AcLys-[D-betaNal7,Ile8]desArg9-bradykinin (BK) (R 715), we prepared and tested 3 analogues containing alpha-methyl-L-Phe ([alphaMe]Phe) in position 5: these are the AcLys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 892), Lys-Lys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 913), and AcLys-Lys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 914). The new compounds were tested against the contractile effect induced by desArg9BK on 2 B1 receptor bioassays, the human umbilical vein, and the rabbit aorta. Their antagonistic activities were compared with those of the early prototypes (Lys-[Leu8]desArg9BK and [Leu8]desArg9BK) and with other recently described peptide antagonists. The 3 (alphaMe)Phe analogues showed high antagonistic potencies (pA2) at both the human (8.8, 7.7, and 8. 7, respectively) and rabbit (8.6, 7.8, and 8.6, respectively) B1 receptors. No antagonistic effects (pA2<5) were observed on the B2 receptors that mediate the contractile effects of BK on the human umbilical vein, the rabbit jugular vein, and the guinea pig ileum. Moreover, these new B1 antagonists were found to be resistant to in vitro degradation by purified angiotensin-converting enzyme from rabbit lung. The Nalpha-acetylated forms, R 892 and R 914, were resistant to aminopeptidases from human plasma. In vivo antagonistic potencies (ID50) of B1 receptor antagonists were evaluated in anesthetized lipopolysaccharide-treated (for B1 receptor) and nontreated (for B2 receptor) rabbits against the hypotensive effects of exogenous desArg9BK and BK. R 892 efficiently inhibited (ID50 2.8 nmol/kg IV) hypotension induced by desArg9BK without affecting that evoked by BK (ID50 >600 nmol/kg IV). Conversely, the peptide antagonists Lys-Lys-[Hyp3,Igl5,D-Igl7,Oic8]desArg9BK (B 9858) and DArg-[Hyp3,Thi5,D-Tic7,Oic8] desArg9BK (S 0765) showed dual B1/B2 receptor antagonism in vitro and in vivo. It is concluded that R 892 and congeners provide selective, highly potent, and metabolically stable B1 kinin receptor antagonists that can be useful for the assessment of the physiological and pathological roles of kinin B1 receptors.

Actions of alpha2 adrenoceptor ligands at alpha2A and 5-HT1A receptors: the antagonist, atipamezole, and the agonist, dexmedetomidine, are highly selective for alpha2A adrenoceptors.

PubMed

Newman-Tancredi, A; Nicolas, J P; Audinot, V; Gavaudan, S; Verrièle, L; Touzard, M; Chaput, C; Richard, N; Millan, M J

1998-08-01

This study examined the activity of chemically diverse alpha2 adrenoceptor ligands at recombinant human (h) and native rat (r) alpha2A adrenoceptors compared with 5-HT1A receptors. First, in competition binding experiments at h alpha2A and h5-HT1A receptors expressed in CHO cells, several compounds, including the antagonists 1-(2-pyrimidinyl)piperazine (1-PP), (+/-)-idazoxan, benalfocin (SKF 86466), yohimbine and RX 821,002, displayed preference for h alpha2A versus h5-HT1A receptors of only 1.4-, 3.6-, 4-, 10- and 11-fold, respectively (based on differences in pKi values). Clonidine, brimonidine (UK 14304), the benzopyrrolidine fluparoxan and the guanidines guanfacine and guanabenz exhibited intermediate selectivity (22- to 31-fold) for h alpha2A receptors. Only the antagonist atipamezole and the agonist dexmedetomidine (DMT) displayed high preference for alpha2 adrenoceptors (1290- and 91-fold, respectively). Second, the compounds were tested for their ability to induce h5-HT1A receptor-mediated G-protein activation, as indicated by the stimulation of [35S]GTPgammaS binding. All except atipamezole and RX 821,002 exhibited agonist activity, with potencies which correlated with their affinity for h5-HT1A receptors. Relative efficacies (Emax values) were 25-35% for guanabenz, guanfacine, WB 4101 and benalfocin, 50-65% for 1-PP, (+/-)-idazoxan and clonidine, and over 70% for fluparoxan, oxymetazoline and yohimbine (relative to 5-HT = 100%). Yohimbine-induced [35S]GTPgammaS binding was inhibited by the selective 5-HT1A receptor antagonist WAY 100,635. In contrast, RX 821,002 was the only ligand which exhibited antagonist activity at h5-HT1A receptors, inhibiting 5-HT-stimulated [35S]GTPgammaS binding. Atipamezole, which exhibited negligeable affinity for 5-HT1A receptors, was inactive. Third, the affinities for r alpha2A differed considerably from the affinities for h alpha2A receptors whereas the affinities for r5-HT1A differed much less from the affinities for h5-HT1A receptors. This affected markedly the affinity ratios of certain compounds. For example, (+/-)-idazoxan was only 3.6-fold selective for h alpha2A versus h5-HT1A but 51-fold selective for r alpha2A versus r5-HT1A receptors. Conversely, yohimbine was tenfold selective for h alpha2A versus h5-HT1A adrenoceptors but 4.2-fold selective for r alpha2A versus r5-HT1A receptors. Nevertheless, both atipamezole and DMT were highly selective for both rat and human alpha2A versus rat or human 5-HT1A receptors. In conclusion, these data indicate that: (1) the agonist DMT and the antagonist atipamezole are the ligands of choice to distinguish alpha2-mediated from 5-HT1A-mediated actions, whilst several of the other compounds show only low or modest selectivity for alpha2A over 5-HT1A receptors; (2) caution should be exercised in experimental and clinical interpretation of the actions of traditionally employed alpha2 ligands, such as clonidine, yohimbine and (+/-)-idazoxan, which exhibit marked agonist activity at 5-HT1A receptors.

Identification of an antagonist that selectively blocks the activity of prostamides (prostaglandin-ethanolamides) in the feline iris.

PubMed

Woodward, D F; Krauss, A H; Wang, J W; Protzman, C E; Nieves, A L; Liang, Y; Donde, Y; Burk, R M; Landsverk, K; Struble, C

2007-02-01

The prostamides (prostaglandin-ethanolamides) and prostaglandin (PG) glyceryl esters are biosynthesized by COX-2 from the respective endocannabinoids anandamide and 2-arachidonyl glycerol. Agonist studies suggest that their pharmacologies are unique and unrelated to prostanoid receptors. This concept was further investigated using antagonists. The isolated feline iris was used as a key preparation, where prostanoid FP receptors and prostamide activity co-exist. Activity at human recombinant FP and other prostanoid receptors was determined using stable transfectants. In the feline iris, AGN 204396 produced a rightward shift of the dose-response curves for prostamide F2alpha and the prostamide F2alpha analog bimatoprost but did not block the effects of PGF2alpha and synthetic FP receptor agonists. Studies on human recombinant prostanoid receptors confirmed that AGN 204396 did not behave as a prostanoid FP receptor antagonist. AGN 204396 exhibited no antagonism at DP and EP1-4, but was a highly effective TP receptor antagonist. Contrary to expectation, the FP receptor antagonist AL-8810 efficaciously contracted the cat iris. AGN 204396 did not affect AL-8810 induced contractions, demonstrating that AL-8810 and AGN 204396 are pharmacologically distinct. Unlike AL-8810, the ethylamide derivate of AL-8810 was not an agonist. Al-8810 did not block prostamide F2alpha activity. Finally, AGN 204396 did not block PGE2-glyceryl ester activity. The ability of AGN 204396 to selectively block prostamide responses suggests the existence of prostamide sensitive receptors as entities distinct from receptors recognizing PGF2alpha and PGE2-glyceryl ester.

Modulation of the storage of social recognition memory by neurotransmitter systems in the insular cortex.

PubMed

Cavalcante, Lorena E S; Zinn, Carolina G; Schmidt, Scheila D; Saenger, Bruna F; Ferreira, Flávia F; Furini, Cristiane R G; Myskiw, Jociane C; Izquierdo, Ivan

2017-09-15

The insular cortex (IC) receives projections from prefrontal, entorhinal and cingulate cortex, olfactory bulb and basal nuclei and has reciprocal connections with the amygdala and entorhinal cortex. These connections suggest a possible involvement in memory processes; this has been borne out by data on several behaviors. Social recognition memory (SRM) is essential to form social groups and to establish hierarchies and social and affective ties. Despite its importance, knowledge about the brain structures and the neurotransmitter mechanisms involved in its processing is still scarce. Here we study the participation of NMDA-glutamatergic, D1/D5-dopaminergic, H2-histaminergic, β-adrenergic and 5-HT 1A -serotoninergic receptors of the IC in the consolidation of SRM. Male Wistar rats received intra-IC infusions of substances acting on these receptors immediately after the sample phase of a social discrimination task and 24h later were exposed to a 5-min retention test. The intra-IC infusion of antagonists of D1/D5, β-adrenergic or 5-HT 1A receptors immediately after the sample phase impaired the consolidation of SRM. These effects were blocked by the concomitant intra-IC infusion of agonists of these receptors. Antagonists and agonists of NMDA and H2 receptors had no effect on SRM. The results suggest that the dopaminergic D1/D5, β-adrenergic and serotonergic 5-HT 1A receptors in the IC, but not glutamatergic NMDA and the histaminergic H2 receptors, participate in the consolidation of SRM in the IC. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of adrenergic stimulation on ventilation in man

PubMed Central

Heistad, Donald D.; Wheeler, Robert C.; Mark, Allyn L.; Schmid, Phillip G.; Abboud, Francois M.

1972-01-01

The mechanism by which catecholamines affect ventilation in man is not known. Ventilatory responses to catecholamines were observed in normal subjects before and after adrenergic receptor blockade. Intravenous infusions of norepinephrine and isoproterenol caused significant increases in minute volume and decreases in end-tidal PCo2 which were blocked by the administration of propranolol, a beta adrenergic receptor blocker. The hyperventilatory response to hypoxia was not altered by propranolol. Intravenous infusion of phenylephrine caused a small but significant decrease in minute volume which was antagonized by phentolamine, an alpha adrenergic receptor blocker. Angiotensin, a nonadrenergic pressor agent, also decreased minute volume significantly. 100% oxygen was administered to suppress arterial chemoreceptors. Increases in minute volume and decreases in arterial PCo2 in response to norepinephrine and isoproterenol were blocked by breathing 100% oxygen. The decrease in minute volume during phenylephrine was not altered by 100% oxygen. The results indicate that: (a) beta adrenergic receptors mediate the hyperventilatory response to norepinephrine and isoproterenol but not to hypoxia. (b) the pressor agents phenylephrine and angiotensin decrease ventilation, and (c) suppression of chemoreceptors blocks the ventilatory response to norepinephrine and isoproterenol but not to phenylephrine. Implications concerning the interaction of adrenergic receptors and chemoreceptors with respect to the hyperventilatory response to catecholamines are discussed. PMID:4336940

Acute effects of a sarin-like organophosphorus agent, bis(isopropyl methyl)phosphonate, on cardiovascular parameters in anaesthetized, artificially ventilated rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Yoshimasa; Itoh, Takeo, E-mail: titoh@med.nagoya-cu.ac.jp; Shiraishi, Hiroaki

The organophosphorus compound sarin irreversibly inhibits acetylcholinesterase. We examined the acute cardiovascular effects of a sarin-like organophosphorus agent, bis(isopropyl methyl)phosphonate (BIMP), in anaesthetized, artificially ventilated rats. Intravenous administration of BIMP (0.8 mg/kg; the LD50 value) induced a long-lasting increase in blood pressure and tended to increase heart rate. In rats pretreated with the non-selective muscarinic-receptor antagonist atropine, BIMP significantly increased both heart rate and blood pressure. In atropine-treated rats, hexamethonium (antagonist of ganglionic nicotinic receptors) greatly attenuated the BIMP-induced increase in blood pressure without changing the BIMP-induced increase in heart rate. In rats treated with atropine plus hexamethonium, intravenous phentolaminemore » (non-selective α-adrenergic receptor antagonist) plus propranolol (non-selective β-adrenergic receptor antagonist) completely blocked the BIMP-induced increases in blood pressure and heart rate. In atropine-treated rats, the reversible acetylcholinesterase inhibitor neostigmine (1 mg/kg) induced a transient increase in blood pressure, but had no effect on heart rate. These results suggest that in anaesthetized rats, BIMP induces powerful stimulation of sympathetic as well as parasympathetic nerves and thereby modulates heart rate and blood pressure. They may also indicate that an action independent of acetylcholinesterase inhibition contributes to the acute cardiovascular responses induced by BIMP. - Highlights: • A sarin-like agent BIMP markedly increased blood pressure in anaesthetized rats. • Muscarinic receptor blockade enhanced the BIMP-induced increase in blood pressure. • Ganglionic nicotinic receptor blockade attenuated the BIMP-induced response. • Blockade of α- as well as β-receptors attenuated the BIMP-induced response.« less

Rotifer neuropharmacology--III. Adrenergic drug effects on Brachionus plicatilis.

PubMed

Keshmirian, J; Nogrady, T

1987-01-01

Norepinephrine (NE) induces three pharmacological effects in Brachionus plicatilis. As a result of excitation the rate of ciliary motion and swimming increases, and the animals flip their foot constantly at a rapid rate. This rapid foot flipping was used as a specific model to measure adrenergic effects in B. plicatilis. Phenylephrine induces the same effect at identical efficacy, while isoproterenol and salbutamol, two beta-agonists, show one-half and one-tenth NE efficacy. The beta blocker propranolol and the alpha blocker tolazoline both antagonize foot flipping induced by NE. However, propranolol shows antagonism because it causes foot paralysis by itself. Timolol, another beta blocker but without the membrane effect of propranolol, does not antagonize the alpha receptor mediated NE effect, nor does it cause foot paralysis. Propranolol, timolol and tolazoline also show agonist activity, inducing foot flipping. NE does not antagonize the foot paralysis induced by propranolol, only its anesthetic effect by delaying its onset. These results indicate that the foot flipping induced by NE is a receptor-mediated alpha adrenergic effect, while the foot paralysis is caused by membrane phenomena.

No role of beta receptors in cognitive flexibility: Evidence from a task-switching paradigm in a randomized controlled trial.

PubMed

Steenbergen, L; Sellaro, R; de Rover, M; Hommel, B; Colzato, L S

2015-06-04

There is evidence that noradrenergic coeruleo-cortical projections are involved in different forms of cognitive flexibility. So far, no studies in humans have investigated the involvement of beta receptors on task-switching performance, a well-established measure of cognitive flexibility. The present study investigated whether the administration of propranolol (a central and peripheral beta-adrenergic antagonist) affected switching costs (i.e., the increase of reaction time in task-switching trials relative to task-repetition trials). Sixteen healthy adult human subjects performed a global-local task-switching paradigm in a double-blind, within-subjects design study investigating the effects of 80mg of propranolol hydrochloride (a β1 and β2 adrenergic receptor antagonist) vs. an oral dose of microcrystalline cellulose (placebo pill). The acute administration of propranolol did not affect the size of switching costs compared to the intake of the neutral placebo. Our results, corroborated by Bayesian inference, suggest that beta receptors do not modulate cognitive flexibility as measured by task-switching performance. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Effect of clonidine on ultrasonic vocalization in preweaning rats.

PubMed

Hård, E; Engel, J; Lindh, A S

1988-01-01

The present study was undertaken to investigate the involvement of the noradrenergic neurotransmission system in the ultra sonic callings emitted by rat pups separated from their mother and exposed to cold stimulation. The investigation was primarily performed by help of agents selectively affecting the alpha-adrenoceptors: the alpha 2-agonist clonidine, the alpha 1-antagonist prazosin and the alpha 2-antagonist idazoxan. Clonidine dose-dependently stimulated the amount of ultra sonic vocalization, an effect not solely dependent upon the effect of clonidine on body temperature. In a developmental study it was found that clonidine uniformly stimulated crying at all ages from 4 days of age up to 18 days of age, that is during the whole preweaning period. Clonidine stimulated ultrasonic crying in rat pups, devoid of presynaptic catecholamine (CA) neurons by combined pretreatment with the monoamine depletor, reserpine, and the inhibitor of CA-synthesis, alpha-methyl-tyrosine. This finding suggested that the stimulating effect of clonidine on ultrasonic vocalization was mediated by postsynaptic adrenoceptors. In pups, 12 days of age, idazoxan blocked the effect of cold stimulation on ultra sonic crying, suggesting that alpha 2-adrenoceptors, presumably postsynaptic ones, mediated this kind of stimulation. Idazoxan also antagonized the effect of clonidine, but only at a dose effective also in control pups. Prazosin had no effect on cold-stimulated crying, but antagonized the effect of clonidine, suggesting that the effect of clonidine was also mediated by alpha 1-receptors. At 18 days of age, prazosin no longer antagonized the effect of clonidine, whereas the antagonizing action of idazoxan was reinforced. The age-dependent variation in responsiveness to the adrenergic drugs suggest maturational changes in the function of the CA-system occurring between 12-16 days of age.

Antidepressant potential of novel flavonoids derivatives from sweet violet (Viola odorata L): Pharmacological, biochemical and computational evidences for possible involvement of serotonergic mechanism.

PubMed

Karim, Nasiara; Khan, Imran; Abdelhalim, Abeer; Khan, Ajmal; Halim, Sobia Ahsan

2018-05-22

Plant-derived natural constituents are of great interest in modern drug discovery due to their natural diversity. Viola odorata L has been traditionally used for the treatment of neuropsychiatric disorders. The present study was undertaken to isolate phytoconstituents including three flavonoids 5,7-Dihydroxy-3,6-dimethoxyflavone[1] 5,7,4'-trihydroxy-3',5'dimethoxyflavone [2] and 5,7,4'-trihydroxy-3'-methoxyflavone [3] from the whole plant of Viola odorata L and to investigate the antidepressant-like effects of these compounds and their possible mechanism of action using antagonists of the serotonergic, dopaminergic and adrenergic system. Classical animal models of depression including tail suspension test (TST) and forced swimming test (FST) using mice were used to evaluate the antidepressant-like effects. Mice were divided into various groups and were administered with either vehicle control, fluoxetine (FLX), or test compounds 1-3 intraperitoneally (i.p.). For experiments involving mechanism determination, mice were pretreated with 5-HT, dopamine and adrenergic antagonists. The brain 5-HT levels were determined following FST. Molecular docking studies were carried out to determine the binding affinity of compounds 1-3 to serotonergic receptors. The results indicated that compounds 1-3 at the dose of 1-30 mg/kg, i.p significantly decreased the immobility time in the FST and TST in mice. The reduction in immobility time was reversed by pre-treating the mice with pCPA (5-HT synthesis inhibitor) 100 mg/kg, i.p. and 5-HT receptor antagonists including WAY100635 (5-HT1a antagonist), ketanserin (a 5-HT2a antagonist) and ondansetron (5-HT3 antagonist) but not with prazosin (α1-adrenergic antagonist) and SCH23390 (D1 dopaminergic antagonist) or haloperidol (D2 dopaminergic antagonist). Moreover, in neurochemical assays, compounds 1-3 caused a significant increase in the 5-HT level in the brain tissue as compared to vehicle. These increases were reversed in the mice groups pretreated with pCPA. Furthermore, molecular docking results also depict that compounds 1-3 can interact with 5HT1A, 5HT2A, and 5HT3 receptors, and are more specific to the 5HT3 receptor subtype. In conclusion, the findings of this study clearly suggest that compounds 1-3 possess antidepressant-like effects which might be mediated via the serotonergic system. Copyright © 2018 Elsevier B.V. All rights reserved.

Pathogen espionage: multiple bacterial adrenergic sensors eavesdrop on host communication systems.

PubMed

Karavolos, Michail H; Winzer, Klaus; Williams, Paul; Khan, C M Anjam

2013-02-01

The interactions between bacterial pathogens and their eukaryotic hosts are vital in determining the outcome of infections. Bacterial pathogens employ molecular sensors to detect and facilitate adaptation to changes in their niche. The sensing of these extracellular signals enables the pathogen to navigate within mammalian hosts. Intercellular bacterial communication is facilitated by the production and sensing of autoinducer (AI) molecules via quorum sensing. More recently, AI-3 and the host neuroendocrine (NE) hormones adrenaline and noradrenaline were reported to display cross-talk for the activation of the same signalling pathways. Remarkably, there is increasing evidence to suggest that enteric bacteria sense and respond to the host NE stress hormones adrenaline and noradrenaline to modulate virulence. These responses can be inhibited by α and β-adrenergic receptor antagonists implying a bacterial receptor-based sensing and signalling cascade. In Escherichia coli O157:H7 and Salmonella, QseC has been proposed as the adrenergic receptor. Strikingly, there is an increasing body of evidence that not all the bacterial adrenergic responses require signalling through QseC. Here we provide additional hypotheses to reconcile these observations implicating the existence of alternative adrenergic receptors including BasS, QseE and CpxA and their associated signalling cascades with major roles in interkingdom communication. © 2012 Blackwell Publishing Ltd.

Differential Modulation of Beta-Adrenergic Receptor Signaling by Trace Amine-Associated Receptor 1 Agonists

PubMed Central

Nürnberg, Daniela; Grüters, Annette; Führer-Sakel, Dagmar; Krude, Heiko; Köhrle, Josef; Schöneberg, Torsten; Biebermann, Heike

2011-01-01

Trace amine-associated receptors (TAAR) are rhodopsin-like G-protein-coupled receptors (GPCR). TAAR are involved in modulation of neuronal, cardiac and vascular functions and they are potentially linked with neurological disorders like schizophrenia and Parkinson's disease. Subtype TAAR1, the best characterized TAAR so far, is promiscuous for a wide set of ligands and is activated by trace amines tyramine (TYR), phenylethylamine (PEA), octopamine (OA), but also by thyronamines, dopamine, and psycho-active drugs. Unfortunately, effects of trace amines on signaling of the two homologous β-adrenergic receptors 1 (ADRB1) and 2 (ADRB2) have not been clarified yet in detail. We, therefore, tested TAAR1 agonists TYR, PEA and OA regarding their effects on ADRB1/2 signaling by co-stimulation studies. Surprisingly, trace amines TYR and PEA are partial allosteric antagonists at ADRB1/2, whereas OA is a partial orthosteric ADRB2-antagonist and ADRB1-agonist. To specify molecular reasons for TAAR1 ligand promiscuity and for observed differences in signaling effects on particular aminergic receptors we compared TAAR, tyramine (TAR) octopamine (OAR), ADRB1/2 and dopamine receptors at the structural level. We found especially for TAAR1 that the remarkable ligand promiscuity is likely based on high amino acid similarity in the ligand-binding region compared with further aminergic receptors. On the other hand few TAAR specific properties in the ligand-binding site might determine differences in ligand-induced effects compared to ADRB1/2. Taken together, this study points to molecular details of TAAR1-ligand promiscuity and identified specific trace amines as allosteric or orthosteric ligands of particular β-adrenergic receptor subtypes. PMID:22073124

Activation and inhibition of mouse muscle and neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes.

PubMed

Papke, Roger L; Wecker, Lynn; Stitzel, Jerry A

2010-05-01

Transgenic mouse models with nicotinic acetylcholine receptor (nAChR) knockouts and knockins have provided important insights into the molecular substrates of addiction and disease. However, most studies of heterologously expressed neuronal nAChR have used clones obtained from other species, usually human or rat. In this work, we use mouse clones expressed in Xenopus oocytes to provide a relatively comprehensive characterization of the three primary classes of nAChR: muscle-type receptors, heteromeric neuronal receptors, and homomeric alpha7-type receptors. We evaluated the activation of these receptor subtypes with acetylcholine and cytisine-related compounds, including varenicline. We also characterized the activity of classic nAChR antagonists, confirming the utility of mecamylamine and dihydro-beta-erythroidine as selective antagonists in mouse models of alpha3beta4 and alpha4beta2 receptors, respectively. We also conducted an in-depth analysis of decamethonium and hexamethonium on muscle and neuronal receptor subtypes. Our data indicate that, as with receptors cloned from other species, pairwise expression of neuronal alpha and beta subunits in oocytes generates heterogeneous populations of receptors, most likely caused by variations in subunit stoichiometry. Coexpression of the mouse alpha5 subunit had varying effects, depending on the other subunits expressed. The properties of cytisine-related compounds are similar for mouse, rat, and human nAChR, except that varenicline produced greater residual inhibition of mouse alpha4beta2 receptors than with human receptors. We confirm that decamethonium is a partial agonist, selective for muscle-type receptors, but also note that it is a nondepolarizing antagonist for neuronal-type receptors. Hexamethonium was a relatively nonselective antagonist with mixed competitive and noncompetitive activity.

Modeling hypertrophic IP3 transients in the cardiac myocyte.

PubMed

Cooling, Michael; Hunter, Peter; Crampin, Edmund J

2007-11-15

Cardiac hypertrophy is a known risk factor for heart disease, and at the cellular level is caused by a complex interaction of signal transduction pathways. The IP3-calcineurin pathway plays an important role in stimulating the transcription factor NFAT which binds to DNA cooperatively with other hypertrophic transcription factors. Using available kinetic data, we construct a mathematical model of the IP3 signal production system after stimulation by a hypertrophic alpha-adrenergic agonist (endothelin-1) in the mouse atrial cardiac myocyte. We use a global sensitivity analysis to identify key controlling parameters with respect to the resultant IP3 transient, including the phosphorylation of cell-membrane receptors, the ligand strength and binding kinetics to precoupled (with G(alpha)GDP) receptor, and the kinetics associated with precoupling the receptors. We show that the kinetics associated with the receptor system contribute to the behavior of the system to a great extent, with precoupled receptors driving the response to extracellular ligand. Finally, by reparameterizing for a second hypertrophic alpha-adrenergic agonist, angiotensin-II, we show that differences in key receptor kinetic and membrane density parameters are sufficient to explain different observed IP3 transients in essentially the same pathway.

Drugs in development for Parkinson's disease: an update.

PubMed

Johnston, Tom H; Brotchie, Jonathan M

2006-01-01

The current development of emerging pharmacological treatments for Parkinson's disease (PD), front preclinical to launch, is summarized. Advances over the past year are highlighted, including the significant progress of several drugs through various stages of development. Several agents have been discontinued from development, either because of adverse effects or lack of clinical efficacy. The methyl-esterified form of L-DOPA (melevodopa) and the monoamine oxidase type B inhibitor rasagiline have both been launched. With regard to the monoamine re-uptake inhibitors, many changes have been witnessed, with new agents reaching preclinical development and pre-existing ones being discontinued or having no development reported. Of the dopamine agonists, many continue to progress successfully through clinical trials. Others have struggled to demonstrate a significant advantage over currently available treatments and have been discontinued. The field of non-dopaminergic treatments remains dynamic. The alpha2 adrenergic receptor antagonists and the adenosine A2A receptor antagonists remain in clinical trials. Trials of the neuronal' synchronization modulator levetiracetam are at an advanced stage, and there has also been a new addition to the class (ie, seletracetam). There has been a change in the landscape of neuroprotective agents that modulate disease progression. Candidates from the classes of growth factors and glyceraldehyde-3-phosphate dehydrogenase inhibitors have been discontinued, or no development has been reported, and the mixed lineage kinase inhibitor CEP-1347 has been discontinued for PD treatment. Other drugs in this field, such as neuroimmunophilins, estrogens and alpha-synuclein oligomerization inhibitors, remain in development.

Intraoperative floppy iris syndrome and its association with various concurrent medications, bulbus length, patient age and gender.

PubMed

Wahl, Michael; Tipotsch-Maca, Saskia M; Vecsei-Marlovits, Pia V

2017-01-01

To evaluate the association between intraoperative floppy iris syndrome (IFIS) and concurrent medications containing selective alpha1A receptor antagonists as well as nonselective alpha1-adrenergic receptor antagonists, bulbus length, patient age and gender. We performed a prospective data acquisition of IFIS occurrence and grading, and retrospective evaluation of concurrent medications, bulbus length, patient age and gender of all patients undergoing cataract surgery over a 6-month period. IFIS was observed in 119 of 947 cases (12.6 %). 31 of those 119 patients (26.1 %) had a concurrent medication with a drug that is associated with a higher risk of causing IFIS. Tamsulosin was the drug most commonly associated with IFIS (n = 11), followed by a combination of drugs (n = 7), doxazosin (n = 4), quetiapine (n = 4), finasterid (n = 2), prothipendyl (n = 2), and mianserin (n = 1). Bulbus length and age did not show any significant association with occurrence or grade of IFIS. Gender distribution among IFIS cases was 57.1 % males (n = 68) and 42.9 % (n = 51) females. The occurrence of IFIS has to be expected with a variety of concurrent medications. The number of IFIS cases and the percentage of females in this series are higher compared to previous reports. The observations might be due to a rising awareness of surgeons or to an increasing number of causative medications on the market.

Amygdala, Anxiety and Alpha(1) Adrenoceptors: Investigations Utilizing a Rodent Model of Traumatic Stress

DTIC Science & Technology

2006-08-23

Hypothalamic-pituitary-adrenocortical (HPA) Lateral hypothalamus (LH) Long-term depression (LTD) Long-term potentiation (LTP) Medial geniculate ...Aghajanian,GK. Activation of lateral geniculate neurons by norepinephrine: mediation by an alpha-adrenergic receptor. Brain Res. 1980;182: 345- 359...expressed in moderate to high levels, whereas 1B and 1D receptors are expressed at low levels. Conversely, in the lateral nucleus, 1B and 1D receptors are

Adrenergic manipulation inhibits pavlovian conditioned approach behaviors.

PubMed

Pasquariello, Kyle Z; Han, Marina; Unal, Cagla; Meyer, Paul J

2018-02-26

Environmental rewards and Pavlovian reward cues can acquire incentive salience, thereby eliciting incentive motivational states and instigate reward-seeking. In rats, the incentive salience of food cues can be measured during a Pavlovian conditioned approach paradigm, in which rats engage in cue-directed approach ("sign-tracking") or approach the food delivery location ("goal-tracking"). While it has been shown that dopamine signaling is necessary for sign-tracking, some studies have suggested that norepinephrine is involved in learning to sign-track as well. Thus, in order to investigate the influence of norepinephrine in Pavlovian conditioned approach, we administered three adrenergic drugs while rats learned that a food cue (an illuminated, retractable lever) preceded the delivery of banana-flavored food pellets into a food-cup. We found that pre-session injections of disulfiram (a dopamine-β-hydroxylase inhibitor) inhibited the development of sign-tracking, but goal-tracking was only affected at the high dose. In one experiment, post-session injections of disulfiram blocked the development of sign-tracking, although this effect was not replicated in a separate set of rats. Post-session injections of prazosin (an α1-adrenergic receptor antagonist) and propranolol (a β-adrenergic receptor antagonist) also blocked the development of sign-tracking but not goal-tracking. Taken together, these results suggest that adrenergic transmission mediates the acquisition of sign-tracking but not goal-tracking, and thus plays a selective role in the attribution of incentive salience food cues. Copyright © 2017 Elsevier B.V. All rights reserved.

Adrenergic receptors in frontal cortex in human brain.

PubMed

Cash, R; Raisman, R; Ruberg, M; Agid, Y

1985-02-05

The binding of three adrenergic ligands ([3H]prazosin, [3H]clonidine, [3H]dihydroalprenolol) was studied in the frontal cortex of human brain. alpha 1-Receptors, labeled by [3H]prazosin, predominated. [3H]Clonidine bound to two classes of sites, one of high affinity and one of low affinity. Guanosine triphosphate appeared to lower the affinity of [3H]clonidine for its receptor. [3H]Dihydroalprenolol bound to three classes of sites: the beta 1-receptor, the beta 2-receptor and a receptor with low affinity which represented about 40% of the total binding, but which was probably a non-specific site; the beta 1/beta 2 ratio was 1/2.

Constitutively active mutants of the alpha 1B-adrenergic receptor: role of highly conserved polar amino acids in receptor activation.

PubMed Central

Scheer, A; Fanelli, F; Costa, T; De Benedetti, P G; Cotecchia, S

1996-01-01

Site-directed mutagenesis and molecular dynamics simulations of the alpha 1B-adrenergic receptor (AR) were combined to explore the potential molecular changes correlated with the transition from R (inactive state) to R (active state). Using molecular dynamics analysis we compared the structural/dynamic features of constitutively active mutants with those of the wild type and of an inactive alpha 1B-AR to build a theoretical model which defines the essential features of R and R. The results of site-directed mutagenesis were in striking agreement with the predictions of the model supporting the following hypothesis. (i) The equilibrium between R and R depends on the equilibrium between the deprotonated and protonated forms, respectively, of D142 of the DRY motif. In fact, replacement of D142 with alanine confers high constitutive activity to the alpha 1B-AR. (ii) The shift of R143 of the DRY sequence out of a conserved 'polar pocket' formed by N63, D91, N344 and Y348 is a feature common to all the active structures, suggesting that the role of R143 is fundamental for mediating receptor activation. Disruption of these intramolecular interactions by replacing N63 with alanine constitutively activates the alpha 1B-AR. Our findings might provide interesting generalities about the activation process of G protein-coupled receptors. Images PMID:8670860

The alpha(2a)-adrenergic receptor plays a protective role in mouse behavioral models of depression and anxiety.

PubMed

Schramm, N L; McDonald, M P; Limbird, L E

2001-07-01

The noradrenergic system is involved in the regulation of many physiological and psychological processes, including the modulation of mood. The alpha(2)-adrenergic receptors (alpha(2)-ARs) modulate norepinephrine release, as well as the release of serotonin and other neurotransmitters, and are therefore potential targets for antidepressant and anxiolytic drug development. The current studies were undertaken to examine the role of the alpha(2A) subtype of alpha(2)-AR in mouse behavioral models of depression and anxiety. We have observed that the genetic knock-out of the alpha(2A)-AR makes mice less active in a modified version of Porsolt's forced swim test and insensitive to the antidepressant effects of the tricyclic drug imipramine in this paradigm. Furthermore, alpha(2A)-AR knock-out mice appear more anxious than wild-type C57 Bl/6 mice in the rearing and light-dark models of anxiety after injection stress. These findings suggest that the alpha(2A)-AR may play a protective role in some forms of depression and anxiety and that the antidepressant effects of imipramine may be mediated by the alpha(2A)-AR.

The neurosteroid 3 alpha-hydroxy-5 alpha-pregnan-20-one affects dopamine-mediated behavior in rodents.

PubMed

Khisti, Rahul T; Deshpande, Laxmikant S; Chopde, Chandrabhan T

2002-05-01

The neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) has been previously shown to induce catalepsy in mice that is modified by GABAergic, dopaminergic, adenosinergic and serotonergic agents. In light of the interaction of this endogenous neurosteroid with GABAergic and dopaminergic transmission, there is potential interest in the possible role of 3alpha,5alpha-THP in psychotic disorders. This study assessed the effect of 3alpha,5alpha-THP in certain dopamine-mediated behavioral paradigms that are widely used to predict antipsychotic-like activity. 3alpha,5alpha-THP (1-8 microg per animal, i.c.v.), the classic neuroleptic (dopamine receptor antagonist) haloperidol (0.25 mg/kg, i.p.), and the benzodiazepine diazepam (7 mg/kg, i.p.) were injected into different groups of animals, and their behavior was screened using the following animal tests: conditioned avoidance response, apomorphine-induced climbing, and amphetamine-induced motor hyperactivity. Separate groups of mice that received 3alpha,5alpha-THP (1-8 microg per animal, i.c.v.) were screened for catalepsy. Furthermore, the effect of a sub-cataleptic dose (0.1 microg per mouse, i.c.v.) of 3alpha,5alpha-THP, either alone or in combination with the GABA(A) receptor antagonist picrotoxin (0.8 mg/kg, i.p.) was measured on haloperidol-induced catalepsy. 3alpha,5alpha-THP like haloperidol reduced conditioned avoidance, apomorphine-induced cage climbing and amphetamine-induced motor hyperactivity. Diazepam only affected conditioned avoidance. 3alpha,5alpha-THP also induced dose-dependent catalepsy. Furthermore, sub-cataleptic doses of 3alpha,5alpha-THP potentiated haloperidol-induced catalepsy. This potentiation was blocked by prior treatment with the GABA(A) receptor antagonist picrotoxin. These findings suggest that 3alpha,5alpha-THP, by its action at the GABA(A) receptors, increases GABAergic tone leading to a behavioral profile similar to that of dopamine receptor antagonists.

Controversial therapeutics: the β-adrenergic antagonist and cocaine-associated cardiovascular complications dilemma.

PubMed

Schurr, James W; Gitman, Brenda; Belchikov, Yuly

2014-12-01

Cocaine abuse is associated with cardiovascular complications that include chest pain and myocardial infarction. Traditional therapy for these conditions includes a β-adrenergic antagonist. However, guidelines released in 2008 recommended against this treatment option because of the prevailing theory that cocaine will potentiate vasospasm secondary to unopposed α-adrenergic effects. Subsequently, further evidence and updated guidelines have become available, debunking this claim. Current literature is limited but suggests that β-adrenergic antagonists are harmful. Although case reports support a detrimental effect of β-adrenergic antagonists, the anecdotal data are inconsistent, and the conclusions from case studies are overruled by larger studies. The pharmacology, pathophysiology, and literature on the use of β-adrenergic antagonists in association with cocaine are reviewed. Future studies that focus on outcomes and different pharmacologic profiles of β-adrenergic antagonists are needed. © 2014 Pharmacotherapy Publications, Inc.

Naftopidil for the treatment of urinary symptoms in patients with benign prostatic hyperplasia

PubMed Central

Masumori, Naoya

2011-01-01

Naftopidil, approved only in Japan, is an α1-adrenergic receptor antagonist (α1-blocker) used to treat lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH). Different from tamsulosin hydrochloride and silodosin, in that it has higher and extremely higher affinity respectively, for the α1A-adrenergic receptor subtype than for the α1D type, naftopidil has distinct characteristics because it has a three times greater affinity for the α1D-adrenergic receptor subtype than for the α1A subtype. Although well-designed large-scale randomized controlled studies are lacking and the optimal dosage of naftopidil is not always completely determined, previous reports from Japan have shown that naftopidil has superior efficacy to a placebo and comparable efficacy to other α1-blockers such as tamsulosin. On the other hand, the incidences of ejaculatory disorders and intraoperative floppy iris syndrome induced by naftopidil may be lower than for tamsulosin and silodosin having high affinity for the α1A-adrenergic receptor subtype. However, it remains unknown if the efficacy and safety of naftopidil in Japanese is applicable to white, black and Hispanic men having LUTS/BPH in western countries. PMID:21753885

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB₁ receptor blockade.

PubMed

Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

2013-03-19

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors.

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB1 receptor blockade

PubMed Central

Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

2013-01-01

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors. PMID:23487769

Preliminary evidence for a role of the adrenergic nervous system in generalized anxiety disorder.

PubMed

Zhang, Xiaobin; Norton, Joanna; Carrière, Isabelle; Ritchie, Karen; Chaudieu, Isabelle; Ryan, Joanne; Ancelin, Marie-Laure

2017-02-15

Generalized anxiety disorder (GAD) is a common chronic condition that is understudied compared to other psychiatric disorders. An altered adrenergic function has been reported in GAD, however direct evidence for genetic susceptibility is missing. This study evaluated the associations of gene variants in adrenergic receptors (ADRs) with GAD, with the involvement of stressful events. Data were obtained from 844 French community-dwelling elderly aged 65 or over. Anxiety disorders were assessed using the Mini-International Neuropsychiatry Interview, according to DSM-IV criteria. Eight single-nucleotide polymorphisms (SNPs) involved with adrenergic function were genotyped; adrenergic receptors alpha(1A) (ADRA1A), alpha(2A) (ADRA2A), and beta2 (ADRB2) and transcription factor TCF7L2. Questionnaires evaluated recent stressful life events as well as early environment during childhood and adolescence. Using multivariate logistic regression analyses four SNPs were significantly associated with GAD. A 4-fold modified risk was found with ADRA1A rs17426222 and rs573514, and ADRB2 rs1042713 which remained significant after Bonferroni correction. Certain variants may moderate the effect of adverse life events on the risk of GAD. Replication in larger samples is needed due to the small case number. This is the first study showing that ADR variants are susceptibility factors for GAD, further highlighting the critical role of the adrenergic nervous system in this disorder.

Preliminary evidence for a role of the adrenergic nervous system in generalized anxiety disorder

PubMed Central

Zhang, Xiaobin; Norton, Joanna; Carrière, Isabelle; Ritchie, Karen; Chaudieu, Isabelle; Ryan, Joanne; Ancelin, Marie-Laure

2017-01-01

Generalized anxiety disorder (GAD) is a common chronic condition that is understudied compared to other psychiatric disorders. An altered adrenergic function has been reported in GAD, however direct evidence for genetic susceptibility is missing. This study evaluated the associations of gene variants in adrenergic receptors (ADRs) with GAD, with the involvement of stressful events. Data were obtained from 844 French community-dwelling elderly aged 65 or over. Anxiety disorders were assessed using the Mini-International Neuropsychiatry Interview, according to DSM-IV criteria. Eight single-nucleotide polymorphisms (SNPs) involved with adrenergic function were genotyped; adrenergic receptors alpha(1A) (ADRA1A), alpha(2A) (ADRA2A), and beta2 (ADRB2) and transcription factor TCF7L2. Questionnaires evaluated recent stressful life events as well as early environment during childhood and adolescence. Using multivariate logistic regression analyses four SNPs were significantly associated with GAD. A 4-fold modified risk was found with ADRA1A rs17426222 and rs573514, and ADRB2 rs1042713 which remained significant after Bonferroni correction. Certain variants may moderate the effect of adverse life events on the risk of GAD. Replication in larger samples is needed due to the small case number. This is the first study showing that ADR variants are susceptibility factors for GAD, further highlighting the critical role of the adrenergic nervous system in this disorder. PMID:28198454

Decreased agonist sensitivity of human GABA(A) receptors by an amino acid variant, isoleucine to valine, in the alpha1 subunit.

PubMed

Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nabekura, J; Noguchi, K; Akaike, N; Witt, M R; Nielsen, M

1997-06-25

Recombinant human GABA(A) receptors were investigated in vitro by coexpression of cDNAs coding for alpha1, beta2, and gamma2 subunits in the baculovirus/Sf-9 insect cell system. We report that a single amino acid exchange (isoleucine 121 to valine 121) in the N-terminal, extracellular part of the alpha1 subunit induces a marked decrease in agonist GABA(A) receptor ligand sensitivity. The potency of muscimol and GABA to inhibit the binding of the GABA(A) receptor antagonist [3H]SR 95531 (2-(3-carboxypropyl)-3-amino-6-(4-methoxyphenyl)pyridazinium bromide) was higher in receptor complexes of alpha1(ile 121) beta2gamma2 than in those of alpha1(val 121) beta2gamma2 (IC50 values were 32-fold and 26-fold lower for muscimol and GABA, respectively). The apparent affinity of the GABA(A) receptor antagonist bicuculline methiodide to inhibit the binding of [3H]SR 95531 did not differ between the two receptor complex variants. Electrophysiological measurements of GABA induced whole-cell Cl- currents showed a ten-fold decrease in the GABA(A) receptor sensitivity of alpha1 (val 121) beta2gamma2 as compared to alpha1(ile 121) beta2gamma2 receptor complexes. Thus, a relatively small change in the primary structure of the alpha1 subunit leads to a decrease selective for GABA(A) receptor sensitivity to agonist ligands, since no changes were observed in a GABA(A) receptor antagonist affinity and benzodiazepine receptor binding.

Cerebral Artery Alpha-1 AR Subtypes: High Altitude Long-Term Acclimatization Responses

PubMed Central

Goyal, Ravi; Goyal, Dipali; Chu, Nina; Van Wickle, Jonathan; Longo, Lawrence D.

2014-01-01

In response to hypoxia and other stress, the sympathetic (adrenergic) nervous system regulates arterial contractility and blood flow, partly through differential activities of the alpha1 (α1) - adrenergic receptor (AR) subtypes (α1A-, α1B-, and α1D-AR). Thus, we tested the hypothesis that with acclimatization to long-term hypoxia (LTH), contractility of middle cerebral arteries (MCA) is regulated by changes in expression and activation of the specific α1-AR subtypes. We conducted experiments in MCA from adult normoxic sheep maintained near sea level (300 m) and those exposed to LTH (110 days at 3801 m). Following acclimatization to LTH, ovine MCA showed a 20% reduction (n = 5; P<0.05) in the maximum tension achieved by 10−5 M phenylephrine (PHE). LTH-acclimatized cerebral arteries also demonstrated a statistically significant (P<0.05) inhibition of PHE-induced contractility in the presence of specific α1-AR subtype antagonists. Importantly, compared to normoxic vessels, there was significantly greater (P<0.05) α1B-AR subtype mRNA and protein levels in LTH acclimatized MCA. Also, our results demonstrate that extracellular regulated kinase 1 and 2 (ERK1/2)-mediated negative feedback regulation of PHE-induced contractility is modulated by α1B-AR subtype. Overall, in ovine MCA, LTH produces profound effects on α1-AR subtype expression and function. PMID:25393740

Cerebral artery alpha-1 AR subtypes: high altitude long-term acclimatization responses.

PubMed

Goyal, Ravi; Goyal, Dipali; Chu, Nina; Van Wickle, Jonathan; Longo, Lawrence D

2014-01-01

In response to hypoxia and other stress, the sympathetic (adrenergic) nervous system regulates arterial contractility and blood flow, partly through differential activities of the alpha1 (α1) - adrenergic receptor (AR) subtypes (α1A-, α1B-, and α1D-AR). Thus, we tested the hypothesis that with acclimatization to long-term hypoxia (LTH), contractility of middle cerebral arteries (MCA) is regulated by changes in expression and activation of the specific α1-AR subtypes. We conducted experiments in MCA from adult normoxic sheep maintained near sea level (300 m) and those exposed to LTH (110 days at 3801 m). Following acclimatization to LTH, ovine MCA showed a 20% reduction (n = 5; P<0.05) in the maximum tension achieved by 10-5 M phenylephrine (PHE). LTH-acclimatized cerebral arteries also demonstrated a statistically significant (P<0.05) inhibition of PHE-induced contractility in the presence of specific α1-AR subtype antagonists. Importantly, compared to normoxic vessels, there was significantly greater (P<0.05) α1B-AR subtype mRNA and protein levels in LTH acclimatized MCA. Also, our results demonstrate that extracellular regulated kinase 1 and 2 (ERK1/2)-mediated negative feedback regulation of PHE-induced contractility is modulated by α1B-AR subtype. Overall, in ovine MCA, LTH produces profound effects on α1-AR subtype expression and function.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 representedmore » 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.« less

Selective inhibition by dactinomycin of NANC sensory bronchoconstriction and [125I]NKA binding due to NK-2 receptor antagonism.

PubMed

Lou, Y P; Delay-Goyet, P; Lundberg, J M

1992-03-01

In the present study, dactinomycin (10(-5) M) inhibited the non-adrenergic, non-cholinergic bronchoconstriction upon antidromic vagal nerve stimulation (1 Hz for 1 min) in the isolated perfused guinea-pig lung by 84%. The release of calcitonin gene-related peptide was unchanged, however, suggesting a postjunctional action. Dactinomycin (10(-5), 5 x 10(-5) M) also reduced non-adrenergic non-cholinergic bronchial contractions (maximally by 75%) induced by electrical field stimulation or capsaicin, while the cholinergic component and non-adrenergic non-cholinergic relaxation remained intact. The neurokinin-2 receptor antagonist L-659,877 (10(-6) M) had a similar effect as dactinomycin, inhibiting the non-adrenergic non-cholinergic bronchial contractions by 69%, while the neurokinin-1 receptor antagonist CP-96,345 (10(-6) M) had no effect. The bronchoconstriction evoked by neurokinin A, the selective neurokinin-2 receptor agonist Nle10neurokinin A (4-10) and capsaicin was markedly inhibited by dactinomycin while the contraction induced by substance P (SP), the selective neurokinin-1 receptor agonist Sar9Met(O2)11SP, endothelin-1 and acetylcholine was not affected. In autoradiographic experiments on guinea-pig lung, [125I]neurokinin A-labelled sections showed dense binding in the bronchial smooth muscle layer. Dactinomycin inhibited the specific binding of [125I]neurokinin A in a concentration-dependent manner (IC50 = 6.3 x 10(-6) M) and 66% of [125I]neurokinin A total binding was inhibited by 10(-4) M dactinomycin. In the rat colon, [125I]neurokinin A binding to neurokinin-2 sites on circular smooth muscle was inhibited by dactinomycin with an IC50 value of 7.9 x 10(-6) M. Dactinomycin failed to reduce increased nerve-evoked contractions or those caused by Nle10neurokinin A (4-10) per se in the rat vas deferens, which are considered to be mediated by neurokinin-2 receptor activation. In the rat portal vein, dactinomycin did not influence the contractions caused by the neurokinin-3 selective agonist Pro7neurokinin B. In conclusion, dactinomycin selectively inhibited neurokinin-2 receptor activation in guinea-pig lung and rat colon, but not in rat vas deferens, which may depend on the existence of different neurokinin-2 receptor subtypes. Neurokinin A is most likely the main endogenous excitatory non-adrenergic non-cholinergic transmitter in guinea-pig bronchi.

Duodenal bicarbonate secretion and mucosal protection. Neurohumoral influence and transport mechanisms.

PubMed

Säfsten, B

1993-01-01

Duodenal mucosal bicarbonate secretion (DMBS) plays an important role in the defence against acid discharged from the stomach. The secretion by duodenum immediately distal to the Brunner's glands area and devoid of pancreatic and biliary secretions, was investigated in vivo in anaesthetized Sprague-Dawley rats and in vitro in mucosae isolated from the American bullfrog. Transport mechanisms were studied in isolated rat duodenal enterocytes and identified by use of digitized microfluorometry and the fluoroprobe BCECF. Cyclic AMP production in enterocytes of villus vs. crypt origin was measured with radioimmunoassay. The benzodiazepines diazepam and Ro 15-1788 stimulated DMBS in the rat when administered intravenously or intracerebroventricularly; however, their stimulatory effect was abolished by bilateral proximal vagotomy, and they had no effect on the secretion by isolated bullfrog mucosa. It is concluded that these benzodiazepines stimulate secretion by acting upon the central nervous system and that their effects are vagally mediated. Dopamine, the catechol-O-methyl-transferase-inhibitor nitecapone, and the dopamine D1 agonist SKF-38393 all stimulated DMBS. The peripherally acting antagonist domperidone while having no influence on basal DMBS did prevent the influences of SKF-38393 and nitecapone. The alpha 1-antagonist prazosin had no such effects and the combined results suggest that DMBS is stimulated via peripheral dopamine D1 receptors. Intravenous, but not central nervous, administration of the muscarinic M1 receptor antagonists pirenzepine and telenzepine effectively stimulated DMBS; however their effectiveness was dependent on intact vagal nerves. Phentolamine, an unselective alpha-adrenergic antagonist, prevented the stimulation by pirenzepine and telenzepine and stimulation by carbachol was abolished by hexamethonium. It is concluded that peripheral nicotinergic and muscarinergic M1 receptors mediate stimulation of DMBS, in part by acting upon peripheral sympathetic ganglia. Whereas dopamine and SKF-38393 caused a time-dependent increase in the accumulation of cyclic AMP in duodenal enterocytes of crypt and villous origin, the D2 agonist quinpirole had an inhibitive influence. Crypt and villus cells differed in their respective time-courses in response to vasoactive intestinal polypeptide. Finally, Cl-/HCO3- exchange, Na+/H+ exchange and NaHCO3 cotransport were identified as membrane acid/base transport mechanisms in isolated duodenal enterocytes.

Alpha 2-adrenoceptor blockade, pituitary-adrenal hormones, and agonistic interactions in rats.

PubMed

Haller, J; Barna, I; Kovács, J L

1994-08-01

The effects of adrenergic activation on aggressiveness and the aggression induced endocrine changes were tested in rats. Alpha 2 adrenoceptor blockers were used for enhancing activation of the adrenergic system, and changes in aggressiveness were tested in resident-intruder contests. Three experiments were conducted. In experiment 1, saline injected rats responded to the presence of an opponent by aggression and the increase in plasma ACTH and corticosterone. Intraperitoneal administration of 1 mg/kg CH-38083 (an alpha 2 adrenoceptor antagonist) produced a several fold increase in clinch fighting and mutual upright scores, and also further enhanced the plasma ACTH and corticosterone response. In experiment 2, the effect of three doses (0.5, 1 and 2 mg/kg) of three different alpha 2 adrenoceptor blockers CH-38083, idazoxan and yohimbine were tested. All the substances increased aggression at 0.5 and 1 mg/kg; at 2 mg/kg the effect of idazoxan and yohimbine disappeared, while with CH-38083 an additional increase was obtained. In yohimbine treated animals the enhancement of aggression was reduced already at 1 mg/kg. In experiment 3, indomethacin, a potent inhibitor of the catecholamine-induced ACTH release completely abolished the effects of the alpha 2 adrenoceptor antagonist CH-38083: the intensity of agonistic interactions, as well as ACTH and corticosterone plasma concentrations, returned to control levels. The possible role of catecholamines and the stress hormones in the activation of aggression is discussed.

Adrenergic factors regulating cell division in the colonic crypt epithelium during carcinogenesis and in colonic adenoma and adenocarcinoma.

PubMed Central

Kennedy, M. F.; Tutton, P. J.; Barkla, D. H.

1985-01-01

Evidence exists implicating adrenergic factors in the control of intestinal epithelial cell proliferation in both normal and diseased states. In this report, attention is focussed on changes in the amine requirements of proliferating cells during the chemical induction of tumours in the colon of mouse. Cell proliferation rates were measured stathmokinetically. Tumours were induced by s.c. injection of dimethylhydrazine (DMH). Results with a series of adrenoceptor agonists and antagonists suggest that there is an alpha 2-adrenoceptor mediated excitatory effect in normal colon but an alpha 2 adrenoceptor mediated inhibitory effect in adenoma and carcinoma. Alpha 1 adrenoceptors, on the other hand, have an inhibitory effect in normal crypts and in adenomas, and an excitatory effect in carcinomas. Beta adrenoceptors have an inhibitory effect in the normal and DMH-treated crypt, and in adenomas, but not in carcinomas. In the crypt epithelium of DMH-treated mice, two regions on cell proliferation, with differing regulatory factors, could be identified. In the upper region of the carcinogen-exposed crypt is a zone where cell proliferation is stimulated by an alpha 2 adrenergic mechanism, thus resembling the basal region of the normal crypt. By contrast, in the basal region of these crypts, cell proliferation is stimulated by an alpha 1 mechanism, thus resembling a malignant tumour. PMID:4041364

Adrenergic factors regulating cell division in the colonic crypt epithelium during carcinogenesis and in colonic adenoma and adenocarcinoma.

PubMed

Kennedy, M F; Tutton, P J; Barkla, D H

1985-09-01

Evidence exists implicating adrenergic factors in the control of intestinal epithelial cell proliferation in both normal and diseased states. In this report, attention is focussed on changes in the amine requirements of proliferating cells during the chemical induction of tumours in the colon of mouse. Cell proliferation rates were measured stathmokinetically. Tumours were induced by s.c. injection of dimethylhydrazine (DMH). Results with a series of adrenoceptor agonists and antagonists suggest that there is an alpha 2-adrenoceptor mediated excitatory effect in normal colon but an alpha 2 adrenoceptor mediated inhibitory effect in adenoma and carcinoma. Alpha 1 adrenoceptors, on the other hand, have an inhibitory effect in normal crypts and in adenomas, and an excitatory effect in carcinomas. Beta adrenoceptors have an inhibitory effect in the normal and DMH-treated crypt, and in adenomas, but not in carcinomas. In the crypt epithelium of DMH-treated mice, two regions on cell proliferation, with differing regulatory factors, could be identified. In the upper region of the carcinogen-exposed crypt is a zone where cell proliferation is stimulated by an alpha 2 adrenergic mechanism, thus resembling the basal region of the normal crypt. By contrast, in the basal region of these crypts, cell proliferation is stimulated by an alpha 1 mechanism, thus resembling a malignant tumour.

The potent free radical scavenger alpha-lipoic acid improves memory in aged mice: putative relationship to NMDA receptor deficits.

PubMed

Stoll, S; Hartmann, H; Cohen, S A; Müller, W E

1993-12-01

alpha-Lipoic acid (alpha-LA) improved longer-term memory of aged female NMRI mice in the habituation in the open field test at a dose of 100 mg/kg body weight for 15 days. In a separate experiment, no such effect could be found for young mice. alpha-LA alleviated age-related NMDA receptor deficits (Bmax) without changing muscarinic, benzodiazepine, and alpha 2-adrenergic receptor deficits in aged mice. The carbachol-stimulated accumulation of inositol monophosphates was not changed by the treatment with alpha-LA. These results give tentative support to the hypothesis that alpha-LA improves memory in aged mice, probably by a partial compensation of NMDA receptor deficits. Possible modes of action of alpha-LA based on its free radical scavenger properties are discussed in relation to the membrane hypothesis of aging.

Spinal GABA-B receptor modulates neutrophil recruitment to the knee joint in zymosan-induced arthritis.

PubMed

Bassi, Gabriel S; do C Malvar, David; Cunha, Thiago M; Cunha, Fernando Q; Kanashiro, Alexandre

2016-08-01

Recent studies have demonstrated that the central nervous system controls inflammatory responses by activating complex efferent neuroimmune pathways. The present study was designed to evaluate the role that central gamma-aminobutyric acid type B (GABA-B) receptor plays in neutrophil migration in a murine model of zymosan-induced arthritis by using different pharmacological tools. We observed that intrathecal administration of baclofen, a selective GABA-B agonist, exacerbated the inflammatory response in the knee after zymosan administration characterized by an increase in the neutrophil recruitment and knee joint edema, whereas saclofen, a GABA-B antagonist, exerted the opposite effect. Intrathecal pretreatment of the animals with SB203580 (an inhibitor of p38 mitogen-activated protein kinase) blocked the pro-inflammatory effect of baclofen. On the other hand, systemic administration of guanethidine, a sympatholytic drug that inhibits catecholamine release, and nadolol, a beta-adrenergic receptor antagonist, reversed the effect of saclofen. Moreover, saclofen suppressed the release of the pro-inflammatory cytokines into the knee joint (ELISA) and pain-related behaviors (open field test). Since the anti-inflammatory effect of saclofen depends on the sympathetic nervous system integrity, we observed that isoproterenol, a beta-adrenergic receptor agonist, mimics the central GABA-B blockade decreasing knee joint neutrophil recruitment. Together, these results demonstrate that the pharmacological manipulation of spinal GABAergic transmission aids control of neutrophil migration to the inflamed joint by modulating the activation of the knee joint-innervating sympathetic terminal fibers through a mechanism dependent on peripheral beta-adrenergic receptors and central components, such as p38 MAPK.

Ca2+ channel blockers interact with alpha 2-adrenergic receptors in rabbit ileum.

PubMed

Homaidan, F R; Donowitz, M; Wicks, J; Cusolito, S; el Sabban, M E; Weiland, G A; Sharp, W G

1988-04-01

An interaction between Ca2+ channel blockers and alpha 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 Ca2+ 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 [3H]alpha 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 Ca2+ 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.

Agemone mexicana flavanones; apposite inverse agonists of the β2-adrenergic receptor in asthma treatment.

PubMed

Eniafe, Gabriel O; Metibemu, Damilohun S; Omotuyi, Olaposi I; Ogunleye, Adewale J; Inyang, Olumide K; Adelakun, Niyi S; Adeniran, Yakubu O; Adewumi, Bamidele; Enejoh, Ojochenemi A; Osunmuyiwa, Joseph O; Shodehinde, Sidiqat A; Oyeneyin, Oluwatoba E

2018-01-01

Asthma is an inflammatory disease of the airway that poses a major threat to human health. With increase industrialization in the developed and developing countries, the incidence of asthma is on the rise. The β2-adrenergic receptor is an important target in designing anti-asthmatic drugs. The synthetic agonists of the β2-adrenergic receptor used over the years proved effective, but with indispensable side effects, thereby limiting their therapeutic use on a long-term scale. Inverse agonists of this receptor, although initially contraindicated, had been reported to have long-term beneficial effects. Phytochemicals from Agemone mexicana were screened against the human β2-adrenergic receptor in the agonist, inverse agonist, covalent agonist, and the antagonist conformations. Molecular docking of the phyto-constituents showed that the plant constituents bind better to the inverse agonist bound conformation of the protein, and revealed two flavanones; eriodictyol and hesperitin, with lower free energy (ΔG) values and higher affinities to the inverse agonist bound receptor than the co-crystallized ligand. Eriodictyol and hesperitin bind with the glide score of -10.684 and - 9.958 kcal/mol respectively, while the standard compound ICI-118551, binds with glide score of -9.503 kcal/mol. Further interaction profiling at the protein orthosteric site and ADME/Tox screening confirmed the drug-like properties of these compounds.

Pharmacological characterization of a β-adrenergic-like octopamine receptor in Plutella xylostella.

PubMed

Huang, Qing-Ting; Ma, Hai-Hao; Deng, Xi-Le; Zhu, Hang; Liu, Jia; Zhou, Yong; Zhou, Xiao-Mao

2018-04-25

The β-adrenergic-like octopamine receptor (OA2B2) belongs to the class of G-protein coupled receptors. It regulates important physiological functions in insects, thus is potentially a good target for insecticides. In this study, the putative open reading frame sequence of the Pxoa2b2 gene in Plutella xylostella was cloned. Orthologous sequence alignment, phylogenetic tree analysis, and protein sequence analysis all showed that the cloned receptor belongs to the OA2B2 protein family. PxOA2B2 was transiently expressed in HEK-293 cells. It was found that PxOA2B2 could be activated by both octopamine and tyramine, resulting in increased intracellular cyclic AMP (cAMP) levels, whereas dopamine and serotonin were not effective in eliciting cAMP production. Further studies with series of PxOA2B2 agonists and antagonists showed that all four tested agonists (e.g., naphazoline, clonidine, 2-phenylethylamine, and amitraz) could activate the PxOA2B2 receptor, and two of tested antagonists (e.g., phentolamine and mianserin) had significant antagonistic effects. However, antagonist of yohimbine had no effects. Quantitative real-time polymerase chain reaction analysis showed that Pxoa2b2 gene was expressed in all developmental stages of P. xylostella and that the highest expression occurred in male adults. Further analysis with fourth-instar P. xylostella larvae showed that the Pxoa2b2 gene was mainly expressed in Malpighian tubule, epidermal, and head tissues. This study provides both a pharmacological characterization and the gene expression patterns of the OA2B2 in P. xylostella, facilitating further research for insecticides using PxOA2B2 as a target. © 2018 Wiley Periodicals, Inc.

Antidepressant-like effect of gallic acid in mice: Dual involvement of serotonergic and catecholaminergic systems.

PubMed

Can, Özgür Devrim; Turan, Nazlı; Demir Özkay, Ümide; Öztürk, Yusuf

2017-12-01

This study was planned to examine the antidepressant potency of gallic acid (30 and 60mg/kg), a phenolic acid widely distributed in nature, together with its possible underlying monoaminergic mechanisms. Antidepressant-like activity was assessed using the tail suspension (TST) and the modified forced swimming tests (MFST). Locomotor activity was evaluated in an activity cage. Administration of gallic acid at 60mg/kg reduced the immobility duration of mice in both the TST and MFST without any changes in the locomotor activity. The anti-immobility effect observed in the TST was abolished with pre-treatment of p-chlorophenylalanine methyl ester (an inhibitor of serotonin synthesis; 100mg/kg i.p. administered for 4-consecutive days), ketanserin (a 5-HT2A/2C antagonist; 1mg/kg i.p.), ondansetron (a 5-HT3 antagonist; 0.3mg/kg i.p.), α-methyl-para-tyrosine methyl ester (an inhibitor of catecholamine synthesis; 100mg/kg i.p.), phentolamine (non-selective alpha-adrenoceptor antagonist; 5mg/kg i.p.), SCH 23390 (a dopamine D1 antagonist; 0.05mg/kg s.c.), and sulpiride (a dopamine D2/D3 antagonist; 50mg/kg i.p.). However, NAN 190 (a 5-HT1A antagonist; 0.5mg/kg i.p.) and propranolol (a non-selective β-adrenoceptor antagonist; 5mg/kg i.p.) pre-treatments were ineffective at reversing the antidepressant-like effects of gallic acid. The results of the present study indicate that gallic acid seems to have a dual mechanism of action by increasing not only serotonin but also catecholamine levels in synaptic clefts of the central nervous system. Further alpha adrenergic, 5-HT2A/2C and 5-HT3 serotonergic, and D1, D2, and D3 dopaminergic receptors also seem to be involved in this antidepressant-like activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Alpha-2 adrenergic receptor-mediated inhibition of thermogenesis

PubMed Central

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

2013-01-01

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

Dorsomedial pontine neurons with descending projections to the medullary reticular formation express orexin-1 and adrenergic alpha2A receptor mRNA.

PubMed

Volgin, Denys V; Malinowska, Monika; Kubin, Leszek

2009-08-14

Neurons located in the dorsomedial pontine rapid eye movement (REM) sleep-triggering region send axons to the medial medullary reticular formation (mMRF). This pathway is believed to be important for the generation of REM sleep motor atonia, but other than that they are glutamatergic little is known about neurochemical signatures of these pontine neurons important for REM sleep. We used single-cell reverse transcription and polymerase chain reaction (RT-PCR) to determine whether dorsomedial pontine cells with projections to the mMRF express mRNA for selected membrane receptors that mediate modulatory influences on REM sleep. Fluorescein (FITC)-labeled latex microspheres were microinjected into the mMRF of 26-34-day-old rats under pentobarbital anesthesia. After 5-6 days, rats were sacrificed, pontine slices were obtained and neurons were dissociated from 400 to 600 microm micropunches extracted from dorsomedial pontine reticular formation. We found that 32 out of 51 FITC-labeled cells tested (63+/-7% (SE)) contained the orexin type 1 receptor (ORX1r) mRNA, 27 out of 73 (37+/-6%) contained the adrenergic alpha(2A) receptor (alpha(2A)r) RNA, and 6 out of 31 (19+/-7%) contained both mRNAs. The percentage of cells positive for the ORX1r mRNA was significantly lower (p<0.04) for the dorsomedial pontine cells that were not retrogradely labeled from the mMRF (32+/-11%), whereas alpha(2A)r mRNA was present in a similar percentage of FITC-labeled and unlabeled neurons. Our data suggest that ORX and adrenergic pathways converge on a subpopulation of cells of the pontine REM sleep-triggering region that have descending projections to the medullary region important for the motor control during REM sleep.

On the Mechanism of Serotonin-Induced Dipsogenesis in the Rat

NASA Technical Reports Server (NTRS)

Kikta, Dianne C.; Barney, Christopher C.; Threatte, Rose M.; Fregly, Melvin J.; Rowland, Neil E.; Greenleaf, John E.

1983-01-01

Subcutaneous administration of 1-5-hydroxytryptophan (5-HTP), the precursor of serotonin, to female rats induces copious drinking accompanied by activation of the renin-angiotensin system. Neither a reduction in blood pressure nor body temperature accompanied administration of 5-HTP. The objective of the present study was to determine whether serotonin-induced dipsogenesis, like that of 5-HTP, is mediated via the renin-angiotensin system. Serotonin (2 mg/kg, SC)-induced drinking was inhibited by the dopaminergic antagonist, haloperidol (150 /micro g/kg, IP), which also inhibits angiotensin II-induced drinking, Both captopril (35 mg/kg, IP), an angiotensin converting enzyme inhibitor, and propranolol (6 micro g/kg, IP), a beta-adrenergic antagonist, blocked serotonin-induced dipsogenesis. The alpha(sub a),-adrenergic agonist, clonidine (6.25 micro g/kg, SC), which suppresses renin release from the kidney, attenuated serotonin-induced water intake. The dipsogenic responses to submaximal concentrations of both serotonin (1 mg/kg, SC) and isoproterenol (8 micro g/kg, SC) were additive rather than interactive suggesting that similar pathways mediate both responses. The serotonergic receptor antagonist, methysergide (3 mg/kg, IP), inhibited serotonin-induced drinking but had no effect on isoproterenol (25micro g/kg, SC)-induced dipsogenesis. However, neither serotonin (2 mg/kg, SC) nor isoproterenol (25 micro g/kg, SC)-induced drinking was inhibited by cinansefin (25 micro g/kg, IP). These data indicate that serotonin induces drinking in rats via the renin-angiotensin system. However, the results of the studies using methysergide suggest that scrotonin appears to act at a point prior to activation of beta-adrenoceptors in the pathway leading to release of renin from the kidneys.

Deletion of CXCR4 in cardiomyocytes exacerbates cardiac dysfunction following isoproterenol administration

PubMed Central

Wang, ER; Jarrah, AA; Benard, L; Chen, J; Schwarzkopf, M; Hadri, L; Tarzami, ST

2014-01-01

Altered alpha- and beta-adrenergic receptor signaling is associated with cardiac hypertrophy and failure. Stromal cell-derived factor-1α (SDF-1α) and its cognate receptor CXCR4 have been reported to mediate cardioprotection after injury through the mobilization of stem cells into injured tissue. However, little is known regarding whether SDF-1/CXCR4 induces acute protection following pathological hypertrophy and if so, by what molecular mechanism. We have previously reported that CXCR4 physically interacts with the beta-2 adrenergic receptor and modulates its down stream signaling. Here we have shown that CXCR4 expression prevents beta-adrenergic receptor induced hypertrophy. Cardiac beta-adrenergic receptors were stimulated with the implantation of a subcutaneous osmotic pump administrating isoproterenol and CXCR4 expression was selectively abrogated in cardiomyocytes using Cre-loxP-mediated gene recombination. CXCR4 knockout mice showed worsened fractional shortening and ejection fraction. CXCR4 ablation increased susceptibility to isoproterenol-induced heart failure, by upregulating apoptotic markers and reducing mitochondrial function; cardiac function decreases while fibrosis increases. Additionally, CXCR4 expression was rescued with the use of cardiotropic Adeno-associated viral-9 (AAV9) vectors. CXCR4 gene transfer reduced cardiac apoptotic signaling, improved mitochondrial function and resulted in a recovered cardiac function. Our results represent the first evidence that SDF-1/CXCR4 signaling mediates acute cardioprotection through modulating beta-adrenergic receptor signaling in vivo. PMID:24646609

Cloning and characterization of the mouse alpha1C/A-adrenergic receptor gene and analysis of an alpha1C promoter in cardiac myocytes: role of an MCAT element that binds transcriptional enhancer factor-1 (TEF-1).

PubMed

O'Connell, T D; Rokosh, D G; Simpson, P C

2001-05-01

alpha1-Adrenergic receptor (AR) subtypes in the heart are expressed by myocytes but not by fibroblasts, a feature that distinguishes alpha1-ARs from beta-ARs. Here we studied myocyte-specific expression of alpha1-ARs, focusing on the subtype alpha1C (also called alpha1A), a subtype implicated in cardiac hypertrophic signaling in rat models. We first cloned the mouse alpha1C-AR gene, which consisted of two exons with an 18 kb intron, similar to the alpha1B-AR gene. The receptor coding sequence was >90% homologous to that of rat and human. alpha1C-AR transcription in mouse heart was initiated from a single Inr consensus sequence at -588 from the ATG; this and a putative polyadenylation sequence 8.5 kb 3' could account for the predominant 11 kb alpha1C mRNA in mouse heart. A 5'-nontranscribed fragment of 4.4 kb was active as a promoter in cardiac myocytes but not in fibroblasts. Promoter activity in myocytes required a single muscle CAT (MCAT) element, and this MCAT bound in vitro to recombinant and endogenous transcriptional enhancer factor-1. Thus, alpha1C-AR transcription in cardiac myocytes shares MCAT dependence with other cardiac-specific genes, including the alpha- and beta-myosin heavy chains, skeletal alpha-actin, and brain natriuretic peptide. However, the mouse alpha1C gene was not transcribed in the neonatal heart and was not activated by alpha1-AR and other hypertrophic agonists in rat myocytes, and thus differed from other MCAT-dependent genes and the rat alpha1C gene.

Isolation and pharmacological characterization of fatty acids from saw palmetto extract.

PubMed

Abe, Masayuki; Ito, Yoshihiko; Suzuki, Asahi; Onoue, Satomi; Noguchi, Hiroshi; Yamada, Shizuo

2009-04-01

Saw palmetto extract (SPE) has been widely used for the treatment of lower urinary-tract symptoms secondary to benign prostatic hyperplasia. The mechanisms of pharmacological effects of SPE include the inhibition of 5alpha-reductase, anti-androgenic effects, anti-proliferative effects, and anti-inflammatory effects. Previously, we showed that SPE bound actively to alpha(1)-adrenergic, muscarinic and 1,4-dihydropyridine calcium channel (1,4-DHP) receptors in the prostate and bladder of rats, whereas its active constituents have not been fully clarified. The present investigation is aimed to identify the main active components contained in hexane and diethyl ether extracts of SPE with the use of column chromatography and preparative HPLC. Based on the binding activity with alpha(1)-adrenergic, muscarinic, and 1,4-DHP receptors, both isolated oleic and lauric acids were deduced to be active components. Authentic samples of oleic and lauric acids also exhibited similar binding activities to these receptors as the fatty acids isolated from SPE, consistent with our findings. In addition, oleic and lauric acids inhibited 5alpha-reductase, possibly leading to therapeutic effects against benign prostatic hyperplasia and related lower urinary-tract symptoms.

The presence and distribution of alpha adrenergic receptors in human renal pelvis and calyces.

PubMed

Karabacak, Osman Raif; Yilmazer, Demet; Ozturk, Ufuk; Sener, Nevzat Can; Saltas, Hakan; Karabacak, Yurdum; Alper, Murat

2013-10-01

In this study, we aimed to demonstrate the presence of Alpha (α) 1 receptors and subtypes in human pelvis and calyces, because an agent to facilitate kidney stone movement and help decrease pain may be an α 1 adrenergic blocker, as used in ureteral stones. Twenty patients who applied to our clinic for renal cell carcinoma were enrolled to the study. All patients underwent radical nephrectomy. After the specimens were removed, excisional biopsies were performed on healthy pelvises and calyces. Mean α-receptor stain rates in renal pelvis were 2.65 ± 0.74, 1.35 ± 0.81 and 2.9 ± 0.30 for α 1A, 1B and 1D, respectively. For calyces, the rates are 2.40 ± 0.82, 1.50 ± 0.76 and 2.75 ± 0.44 for α 1A, 1B and 1D, respectively (Fig. 1). When the staining patterns were compared, α 1A and 1D were expressed more in both pelvis and calyces than α 1B (p < 0.05). After the demonstration of α-adrenergic receptors in pelvis and calyces of human kidney, it may be helpful in coming up with new alternative treatments for patients suffering from kidney stones.

β1-Adrenoceptor in the Central Amygdala Is Required for Unconditioned Stimulus-Induced Drug Memory Reconsolidation

PubMed Central

Zhu, Huiwen; Zhou, Yiming; Liu, Zhiyuan; Chen, Xi; Li, Yanqing; Liu, Xing; Ma, Lan

2018-01-01

Abstract Background Drug memories become labile and reconsolidated after retrieval by presentation of environmental cues (conditioned stimulus) or drugs (unconditioned stimulus). Whether conditioned stimulus and unconditioned stimulus retrieval trigger different memory reconsolidation processes is not clear. Methods Protein synthesis inhibitor or β-adrenergic receptor (β-AR) antagonist was systemically administrated or intra-central amygdala infused immediately after cocaine reexposure in cocaine-conditioned place preference or self-administration mice models. β-ARs were selectively knocked out in the central amygdala to further confirm the role of β-adrenergic receptor in cocaine reexposure-induced memory reconsolidation of cocaine-conditioned place preference. Results Cocaine reexposure triggered de novo protein synthesis dependent memory reconsolidation of cocaine-conditioned place preference. Cocaine-priming-induced reinstatement was also impaired with post cocaine retrieval manipulation, in contrast to the relapse behavior with post context retrieval manipulation. Cocaine retrieval, but not context retrieval, induced central amygdala activation. Protein synthesis inhibitor or β1-adrenergic receptor antagonist infused in the central amygdala after cocaine retrieval, but not context retrieval, inhibited memory reconsolidation and reinstatement. β1-adrenergic receptor knockout in the central amygdala suppressed cocaine retrieval-triggered memory reconsolidation and reinstatement of cocaine conditioned place preference. β1-adrenergic receptor antagonism after cocaine retrieval also impaired reconsolidation and reinstatement of cocaine self-administration. Conclusions Cocaine reward memory triggered by unconditioned stimulus retrieval is distinct from conditioned stimulus retrieval. Unconditioned stimulus retrieval induced reconsolidation of cocaine reward memory depends on β1-adrenergic signaling in the central amygdala. Post unconditioned stimulus retrieval manipulation can prevent drug memory reconsolidation and relapse to cocaine, thus providing a potential strategy for the prevention of substance addiction. Significance Statement It is well known that drug memories become labile and reconsolidated upon retrieval by the presentation of conditioned stimulus (CS) or unconditioned stimulus (US). Whether CS and US retrieval trigger different memory reconsolidation processes is unknown. In this study, we found that US retrieval, but not CS retrieval, triggered memory reconsolidation of cocaine-conditioned place preference dependent on β1-AR and de novo protein synthesis in the central amygdala. Furthermore, cocaine priming-induced reinstatement was impaired with post US retrieval manipulation in contrast to the relapse behavior with post CS retrieval manipulation. In cocaine self-administration, β1-AR antagonism after US retrieval also impaired reconsolidation and reinstatement. Our study indicates that reconsolidation of cocaine reward memory triggered by US retrieval is distinct from CS retrieval. US retrieval induced reconsolidation of cocaine reward memory depends on β1-adrenergic signaling in the central amygdala. PMID:29216351

Conserved Binding Mode of Human [beta subscript 2] Adrenergic Receptor Inverse Agonists and Antagonist Revealed by X-ray Crystallography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wacker, Daniel; Fenalti, Gustavo; Brown, Monica A.

2010-11-15

G protein-coupled receptors (GPCRs) represent a large fraction of current pharmaceutical targets, and of the GPCRs, the {beta}{sub 2} adrenergic receptor ({beta}{sub 2}AR) is one of the most extensively studied. Previously, the X-ray crystal structure of {beta}{sub 2}AR has been determined in complex with two partial inverse agonists, but the global impact of additional ligands on the structure or local impacts on the binding site are not well-understood. To assess the extent of such ligand-induced conformational differences, we determined the crystal structures of a previously described engineered {beta}{sub 2}AR construct in complex with two inverse agonists: ICI 118,551 (2.8 {angstrom}),more » a recently described compound (2.8 {angstrom}) (Kolb et al, 2009), and the antagonist alprenolol (3.1 {angstrom}). The structures show the same overall fold observed for the previous {beta}{sub 2}AR structures and demonstrate that the ligand binding site can accommodate compounds of different chemical and pharmacological properties with only minor local structural rearrangements. All three compounds contain a hydroxy-amine motif that establishes a conserved hydrogen bond network with the receptor and chemically diverse aromatic moieties that form distinct interactions with {beta}{sub 2}AR. Furthermore, receptor ligand cross-docking experiments revealed that a single {beta}{sub 2}AR complex can be suitable for docking of a range of antagonists and inverse agonists but also indicate that additional ligand-receptor structures may be useful to further improve performance for in-silico docking or lead-optimization in drug design.« less

Evidence that shock-induced immune suppression is mediated by adrenal hormones and peripheral beta-adrenergic receptors.

PubMed

Cunnick, J E; Lysle, D T; Kucinski, B J; Rabin, B S

1990-07-01

Our previous work has demonstrated that presentations of mild foot-shock to Lewis rats induces a suppression of splenic and peripheral blood lymphocyte responses to nonspecific T-cell mitogens. The present study demonstrated that adrenalectomy prevented the shock-induced suppression of the mitogenic response of peripheral blood T-cells but did not attenuate the suppression of splenic T-cells. Conversely, the beta-adrenergic receptor antagonists, propranolol and nadolol, attenuated the shock-induced suppression of splenic T-cells in a dose-dependent manner but did not attenuate suppression of the blood mitogen response. These data indicate that distinct mechanisms mediate the shock-induced suppression of T-cell responsiveness to mitogens in the spleen and the peripheral blood. The results indicate that the peripheral release of catecholamines is responsible for splenic immune suppression and that adrenal hormones, which do not interact with beta-adrenergic receptors, are responsible for shock-induced suppression of blood mitogenic responses.

Endogenous calcitonin gene-related peptide (CGRP) mediates adrenergic-dependent vasodilation induced by nicotine in mesenteric resistance arteries of the rat

PubMed Central

Shiraki, Hinako; Kawasaki, Hiromu; Tezuka, Satoko; Nakatsuma, Akira; Kurosaki, Yuji

2000-01-01

The mechanisms underlying vasodilator effect of nicotine on mesenteric resistance blood vessels and the role of calcitonin gene-related peptide (CGRP)-containing (CGRPergic) vasodilator nerves were studied in the rat. Mesenteric vascular beds isolated from Wistar rats were perfused with Krebs solution, and perfusion pressure was measured with a pressure transducer. In preparations with intact endothelium and contracted by perfusion with Krebs solution containing methoxamine, perfusion of nicotine (1–100 μM) for 1 min caused a concentration-dependent vasodilator response without vasoconstriction. The nicotine-induced vasodilation was markedly inhibited by hexamethonium (nicotinic cholinoceptor antagonist, 10 μM) and blocked by guanethidine (adrenergic neuron blocker, 5 μM). Either denervation by cold storage (4°C for 72 h) or adrenergic denervation by 6-hydroxydopamine (toxin for adrenergic neurons, 2 mM for 20 min incubation, twice) blocked the nicotine-induced vasodilation. Neither endothelium removal with perfusion of sodium deoxycholate (1.80 mg ml−1, for 30 s) nor treatment with Nω-nitro-L-arginine (nitric oxide synthase inhibitor, 100 μM), atropine (muscarinic cholinoceptor antagonist, 10 nM) or propranolol (β-adrenoceptor antagonist, 100 nM) affected the nicotine-induced vasodilation. In preparations without endothelium, treatment with capsaicin (depleting CGRP-containing sensory nerves, 1 μM) or human CGRP[8–37] (CGRP receptor antagonist, 0.5 μM) markedly inhibited the nicotine-induced vasodilation. These results suggest that, in the mesenteric resistance artery of the rat, nicotine induces vasodilation, which is independent of the function of the endothelium and is involved in activation of CGRPergic nerves. It is also suggested that nicotine stimulates presynaptic nicotinic cholinoceptors on adrenergic nerves to release adrenergic neurotransmitters, which then act on CGRPergic nerves to release endogenous CGRP from the nerve. PMID:10882393

High-expression β(1) adrenergic receptor/cell membrane chromatography method based on a target receptor to screen active ingredients from traditional Chinese medicines.

PubMed

Yue, Yuan; Xue, Hui; Wang, Xin; Yang, Qian; Song, Yanhong; Li, Xiaoni

2014-02-01

β-Adrenergic receptors are important targets for drug discovery. We have developed a new β1 -adrenergic receptor cell membrane chromatography (β1 AR-CMC) with offline ultra-performance LC (UPLC) and MS method for screening active ingredients from traditional Chinese medicines. In this study, Chinese hamster ovary-S cells with high β1 AR expression levels were established and used to prepare a cell membrane stationary phase in a β1 AR-CMC model. The retention fractions were separated and identified by the UPLC-MS system. The screening results found that isoimperatorin from Rhizoma et Radix Notopterygii was the targeted component that could act on β1 AR in similar manner of metoprolol as a control drug. In addition, the biological effects of active component were also investigated in order to search for a new type of β1 AR antagonist. It will be a useful method for drug discovery as a leading compound resource. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Adrenaline stimulates the proliferation and migration of mesenchymal stem cells towards the LPS-induced lung injury

PubMed Central

Wu, Xiaodan; Wang, Zhiming; Qian, Mengjia; Wang, Lingyan; Bai, Chunxue; Wang, Xiangdong

2014-01-01

Bone marrow-derived mesenchymal stem cells (BMSCs) could modulate inflammation in experimental lung injury. On the other hand, adrenergic receptor agonists could increase DNA synthesis of stem cells. Therefore, we investigated the therapeutic role of adrenaline-stimulated BMSCs on lipopolysaccharide (LPS)-induced lung injury. BMSCs were cultured with adrenergic receptor agonists or antagonists. Suspensions of lung cells or sliced lung tissue from animals with or without LPS-induced injury were co-cultured with BMSCs. LPS-stimulated alveolar macrophages were co-cultured with BMSCs (with adrenaline stimulation or not) in Transwell for 6 hrs. A preliminary animal experiment was conducted to validate the findings in ex vivo study. We found that adrenaline at 10 μM enhanced proliferation of BMSCs through both α- and β-adrenergic receptors. Adrenaline promoted the migration of BMSCs towards LPS-injured lung cells or lung tissue. Adrenaline-stimulated BMSCs decreased the inflammation of LPS-stimulated macrophages, probably through the expression and secretion of several paracrine factors. Adrenaline reduced the extent of injury in LPS-injured rats. Our data indicate that adrenaline-stimulated BMSCs might contribute to the prevention from acute lung injury through the activation of adrenergic receptors, promotion of proliferation and migration towards injured lung, and modulation of inflammation. PMID:24684532

Discovery of an imidazopyridine-containing 1,4-benzodiazepine nonpeptide vitronectin receptor (alpha v beta 3) antagonist with efficacy in a restenosis model.

PubMed

Keenan, R M; Lago, M A; Miller, W H; Ali, F E; Cousins, R D; Hall, L B; Hwang, S M; Jakas, D R; Kwon, C; Louden, C; Nguyen, T T; Ohlstein, E H; Rieman, D J; Ross, S T; Samanen, J M; Smith, B R; Stadel, J; Takata, D T; Vickery, L; Yuan, C C; Yue, T L

1998-11-17

In the 3-oxo-1,4-benzodiazepine-2-acetic acid series of vitronectin receptor (alpha v beta 3) antagonists, a compound containing an imidazopyridine arginine mimetic was discovered which had sufficient potency and i.v. pharmacokinetics for demonstration of efficacy in a rat restenosis model.

Atypical sympathomimetic drug lerimazoline mediates contractile effects in rat aorta predominantly by 5-HT2A receptors.

PubMed

Rizvić, Eldina; Janković, Goran; Kostić-Rajačić, Slađana; Savić, Miroslav M

2017-08-20

Lerimazoline is a sympathomimetic drug that belongs to the imidazoline class of compounds, and is used as a nasal decongestant. Studies on lerimazoline are rare, and its pharmacological profile is not completely understood. Here, we analyzed the affinity of lerimazoline for dopamine receptor D2, serotonin 5-HT1A and 5-HT2A receptors and α1-adrenoceptor, and investigated lerimazoline contractile effects in isolated rat thoracic aorta. We also determined the effect of several antagonists on the contractile response to lerimazoline, including prazosin (α1-adrenoceptor antagonist), RX 821002 and rauwolscine (α2-adrenoceptor antagonists), JP 1302 (α2C-adrenoceptor antagonist), methiothepin (non-selective 5-HT receptor antagonist), SB 224289 (5-HT1B receptor antagonist), BRL 15572 (5-HT1D receptor antagonist), and ketanserin (5-HT2A receptor antagonist). Lerimazoline displayed high affinity for the 5-HT1A receptor (Ki = 162.5 nM), similar to the previously reported affinity for the 5-HT1D receptor. Binding affinity estimates (Ki) for α1, 5-HT2A, and D2 receptors were 6656, 4202 and 3437.5 nM, respectively (the literature reported Ki for 5-HT1B receptor is 3480 nM). Lerimazoline caused concentration-dependent contractions in 70% of preparations, varying in the range between 40% and 55% of the maximal contraction elicited by phenylephrine. While prazosin reduced the maximum contractile response to lerimazoline, rauwolscine showed a non-significant trend in reduction of the response. Both ketanserin (10 nM and 1 µM) and methiothepin strongly suppressed the maximum response to lerimazoline. Overall, our results suggest that 5-HT2A and, less distinctly, α1-adrenergic receptors are involved in the lerimazoline-induced contractions, which makes lerimazoline an "atypical" decongestant.

Adrenergic antagonists restrict replication of Legionella.

PubMed

Harrison, Christopher F; Kicka, Sébastien; Kranjc, Agata; Finsel, Ivo; Chiriano, Gianpaolo; Ouertatani-Sakouhi, Hajer; Soldati, Thierry; Scapozza, Leonardo; Hilbi, Hubert

2015-07-01

Legionella pneumophila is a facultative intracellular bacterium, which upon inhalation can cause a potentially fatal pneumonia termed Legionnaires' disease. The opportunistic pathogen grows in environmental amoebae and mammalian macrophages within a unique membrane-bound compartment, the 'Legionella-containing vacuole'. Bacteria are exposed to many environmental cues including small signalling molecules from eukaryotic cells. A number of pathogenic bacteria sense and respond to catecholamine hormones, such as adrenalin and noradrenalin, a process mediated via the QseBC two-component system in some bacteria. In this study, we examined the effect of adrenergic compounds on L. pneumophila, and discovered that the adrenergic receptor antagonists benoxathian, naftopidil, propranolol and labetalol, as well as the QseC sensor kinase inhibitor LED209, reduced the growth of L. pneumophila in broth or amoebae, while replication in macrophages was enhanced. Growth restriction was common to members of the genus Legionella and Mycobacterium, and was observed for L. pneumophila in the replicative but not stationary phase of the biphasic life cycle. Deletion of the L. pneumophila qseBC genes indicated that growth inhibition by adrenergics or LED209 is mediated only to a minor extent by this two-component system, implying the presence of other adrenergic sensing systems. This study identifies adrenergic molecules as novel inhibitors of extra- and intracellular growth of Legionella and reveals LED209 as a potential lead compound to combat infections with Legionella or Mycobacterium spp.

Alpha adrenergic regulation of celiac blood flow and plasma catecholamine response during acute heat stress in fed cockerels.

PubMed

Bottje, W G; Harrison, P C

1986-08-01

Hubbard cockerels with chronically implanted electromagnetic blood flow probes on the celiac artery were used to establish a relationship between changes in postprandial celiac mean blood flow (MBF) and plasma catecholamines during a acute heat exposure. Five min after the elevation of ambient temperature from 25 to 37 C, there were concomitant reductions (P less than .05) in celiac MBF, norepinephrine (NE), and heart rate (HR). After 50 min of heat stress, rectal temperature (Tr), respiratory rate (RR), plasma epinephrine (E), and celiac vascular resistance (CVR) were significantly greater (P less than .05) than preheat stress thermoneutral control values. During the thermoneutral recovery period, all parameters returned to values comparable to preheat exposure control with the exception of NE, which tended (P less than .1) to remain lower. To determine the role of the sympathetic nervous system in regulating postprandial celiac MBF during acute heat exposure, chronically instrumented cockerels were infused with phenoxybenzamine, an alpha-adrenergic receptor-blocking agent. Alpha-receptor blockade attenuated both postprandial intestinal hyperemia under thermoneutral conditions as well as the heat-induced reduction of postprandial celiac MBF. The results of these studies implicate the sympathetic nervous system in the regulation of postprandial celiac MBF in heat-stressed cockerels and indicate a possible alpha-adrenergic-mediated mechanism involved in postprandial intestinal hyperemia.

Mechanisms of blood pressure alterations in response to the Valsalva maneuver in postural tachycardia syndrome

NASA Technical Reports Server (NTRS)

Sandroni, P.; Novak, V.; Opfer-Gehrking, T. L.; Huck, C. A.; Low, P. A.

2000-01-01

The postural tachycardia syndrome (POTS) is characterized clinically by orthostatic lightheadedness and tachycardia. When these patients perform a Valsalva maneuver, there is an excessive blood pressure increment after cessation of the maneuver (phase IV) that is sometimes associated with headaches. It is not known whether excessive phase IV is due to excessive peripheral vascular tone (an alpha-adrenergic mechanism) or is a manifestation of increased beta-adrenergic tone (hyperadrenergic state). The authors undertook a pharmacologic study evaluating the effect of intravenous phentolamine (alpha-adrenergic antagonist) and propranolol (beta-adrenergic antagonist) on the different phases of the Valsalva maneuver in a group of patients with POTS and age-matched normal control subjects. Patients with POTS had mean phases, when compared with controls, that were characterized by more negative II_E (p = 0.07), smaller II_L (p = 0.04), and significantly larger phase IV (p = 0.001). The effect of phentolamine was qualitatively and quantitatively different in POTS when compared with controls. Ten mg phentolamine in controls resulted in a significant accentuation of phase II_E (p = 0.001), attenuation of phase II_L (p = 0.002), and increase of phase IV (57.6 vs 30.7 mm Hg; p = 0.025). These changes resembled those of patients with POTS at baseline. In patients with POTS, the phase II abnormalities, already present, were further accentuated (p <0.001), and phase IV became smaller (50.6 vs 73.8 mm Hg; p = 0.09). Propranolol had no significant effect on phases II_E and II_L, but significantly reduced phase IV in both controls (p <0.05) and in patients with POTS (p <0.001) and improved the headache symptoms, when present, during and after phase IV. The authors conclude that phase IV is mainly under beta-adrenergic regulation and that the exaggerated phase IV in POTS is a result of a hyperadrenergic state.

Leptin regulates bone formation via the sympathetic nervous system

NASA Technical Reports Server (NTRS)

Takeda, Shu; Elefteriou, Florent; Levasseur, Regis; Liu, Xiuyun; Zhao, Liping; Parker, Keith L.; Armstrong, Dawna; Ducy, Patricia; Karsenty, Gerard

2002-01-01

We previously showed that leptin inhibits bone formation by an undefined mechanism. Here, we show that hypothalamic leptin-dependent antiosteogenic and anorexigenic networks differ, and that the peripheral mediators of leptin antiosteogenic function appear to be neuronal. Neuropeptides mediating leptin anorexigenic function do not affect bone formation. Leptin deficiency results in low sympathetic tone, and genetic or pharmacological ablation of adrenergic signaling leads to a leptin-resistant high bone mass. beta-adrenergic receptors on osteoblasts regulate their proliferation, and a beta-adrenergic agonist decreases bone mass in leptin-deficient and wild-type mice while a beta-adrenergic antagonist increases bone mass in wild-type and ovariectomized mice. None of these manipulations affects body weight. This study demonstrates a leptin-dependent neuronal regulation of bone formation with potential therapeutic implications for osteoporosis.

INCREASED OXIDATIVE STRESS AND DOWN REGULATION OF ENDOTHELIAL NITRIC OXIDE SYNTHASE (ENOS) IN THE KIDNEY ATTEN- UATE THE RESPONSIVENESS OF (XlB ADRENERGIC RECEPTORS IN THE KIDNEY OF RATS WITH LEFT VENTRICULAR HYPERTROPHY.

PubMed

Ahmad, Ashfaq; Sattar, Munavvar; Khan, Safia Akhtar; Abdullah, Nor A; Johns, Edward J; Afzal, Samina

2017-03-01

Present study explored endothelial nitric oxide synthase/nitric oxide (eNOS/NO) pathway in the kidney and role of αIB adrenergic receptor in the regulation of renal vasculature in the rats with left ventricular hypertrophy (LVH). LVH was induced by administering isoprenaline 5 mg/kg (s.c. 72 h. apart) and caffeine (62 mg/L in drinking water) for 14 days. Quantification of molecular expression of eNOS in kidney was performed by quantitative Real Time Polymerase Chain Reaction (qPCR). Renal vasoconstrictor responses were measured by administering noradrenaline (NA), phenylephrine (PE) and methoxamine (ME) in pre-drug phase, low dose and high dose phases of chloroethylelonidine (CEC), a selective of (αIB adrenergic receptor antagonist. In the kidney of LVH male Wistar Kyoto (WKY) rats eNOS was significantly down regulated (p < 0.05) by 74% relative to Control WKY (taken as 100%). The high dose 5 CEC attenuated the vasoconstrictor responses to NA by 41%, PE by 43% and ME by 33% in the LVH-WKY when compared to the same dose phase in Control WKY group. In LVH, increased oxidative stress in kidney and increased ACE activity in the plasma resulted in down regulation of eNOS/NO in the kidney. The renal vasoconstrictor responses to adrenergic agonist are blunted in LVH and (αIB adrenergic receptor is functional subtype in renal vasculature in LVH.

Limited Efficacy of Propranolol on the Reconsolidation of Fear Memories

ERIC Educational Resources Information Center

Muravieva, Elizaveta V.; Alberini, Cristina M.

2010-01-01

Previous studies suggested that the beta-adrenergic receptor antagonist propranolol might be a novel, potential treatment for post-traumatic stress disorder (PTSD). This hypothesis stemmed mainly from rodent studies showing that propranolol interferes with the reconsolidation of Pavlovian fear conditioning (FC). However, subsequent investigations…

Noradrenaline and alpha-adrenergic signaling induce the hsp70 gene promoter in mollusc immune cells.

PubMed

Lacoste, A; De Cian, M C; Cueff, A; Poulet, S A

2001-10-01

Expression of heat shock proteins (hsp) is a homeostatic mechanism induced in both prokaryotic and eukaryotic cells in response to metabolic and environmental insults. A growing body of evidence suggests that in mammals, the hsp response is integrated with physiological responses through neuroendocrine signaling. In the present study, we have examined the effect of noradrenaline (NA) on the hsp70 response in mollusc immune cells. Oyster and abalone hemocytes transfected with a gene construct containing a gastropod hsp70 gene promoter linked to the luciferase reporter-gene were exposed to physiological concentrations of NA, or to various alpha- and beta-adrenoceptor agonists and antagonists. Results show that NA and alpha-adrenergic stimulations induced the expression of luciferase in transfected mollusc immunocytes. Furthermore, exposure of hemocytes to NA or to the alpha-adrenoceptor agonist phenylephrine (PE) resulted in the expression of the inducible isoform of the hsp70 protein. Pertussis toxin (PTX), the phospholipase C (PLC) inhibitor U73122, the protein kinase C (PKC) inhibitor calphostin C, the Ca(2+)-dependent PKC inhibitor Gö 6976 and the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor LY294002 blocked the PE-mediated induction of the hsp70 gene promoter. These results suggest that alpha-adrenergic signaling induces the transcriptionnal upregulation of hsp70 in mollusc hemocytes through a PTX-sensitive G-protein, PLC, Ca(2+)-dependent PKC and PI 3-kinase. Thus, a functional link exists between neuroendocrine signaling and the hsp70 response in mollusc immune cells.

The effects of alpha2-adrenoceptor agents on anti-hyperalgesic effects of carbamazepine and oxcarbazepine in a rat model of inflammatory pain.

PubMed

Vucković, Sonja M; Tomić, Maja A; Stepanović-Petrović, Radica M; Ugresić, Nenad; Prostran, Milica S; Bosković, Bogdan

2006-11-01

In this study, the effects of yohimbine (alpha2-adrenoceptor antagonist) and clonidine (alpha2-adrenoceptor agonist) on anti-hyperalgesia induced by carbamazepine and oxcarbazepine in a rat model of inflammatory pain were investigated. Carbamazepine (10-40 mg/kg; i.p.) and oxcarbazepine (40-160 mg/kg; i.p.) caused a significant dose-dependent reduction of the paw inflammatory hyperalgesia induced by concanavalin A (Con A, intraplantarly) in a paw pressure test in rats. Yohimbine (1-3 mg/kg; i.p.) significantly depressed the anti-hyperalgesic effects of carbamazepine and oxcarbazepine, in a dose- and time-dependent manner. Both drug mixtures (carbamazepine-clonidine and oxcarbazepine-clonidine) administered in fixed-dose fractions of the ED50 (1/2, 1/4 and 1/8) caused significant and dose-dependent reduction of the hyperalgesia induced by Con A. Isobolographic analysis revealed a significant synergistic (supra-additive) anti-hyperalgesic effect of both combinations tested. These results indicate that anti-hyperalgesic effects of carbamazepine and oxcarbazepine are, at least partially, mediated by activation of adrenergic alpha2-receptors. In addition, synergistic interaction for anti-hyperalgesia between carbamazepine and clonidine, as well as oxcarbazepine and clonidine in a model of inflammatory hyperalgesia, was demonstrated.

Forskolin promotes the development of ethanol tolerance in 6-hydroxydopamine-treated mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szabo, G.; Hoffman, P.L.; Tabakoff, B.

1988-01-01

Partial depletion of brain norepinephrine by 6-hydroxydopamine prevents the development of functional tolerance to ethanol in mice. This blockade of tolerance development was overcome by daily intracerebroventricular injections of forskolin. These results suggest that interaction of norepinephrine with post-synaptic ..beta..-adrenergic receptors, and activation of adenylate cyclase, is important for the development of ethanol tolerance. Interaction of norepinephrine with ..cap alpha../sub 1/-adrenergic receptors may be less crucial, since treatment with a phorbol ester activator of protein kinase C did not restore the development of tolerance in mice treated with 6-hydroxydopamine. The importance of the ..beta..-adrenergic receptor-coupled adenylate cyclase system for developmentmore » of ethanol tolerance, in addition to its previously-reported role in long-term potentiation, suggests that this system may influence neuroadaptive processes in general. 26 references, 2 figures.« less

Persistent Catechol-O-methyltransferase-dependent Pain Is Initiated by Peripheral β-Adrenergic Receptors.

PubMed

Ciszek, Brittney P; O'Buckley, Sandra C; Nackley, Andrea G

2016-05-01

Patients with chronic pain disorders exhibit increased levels of catecholamines alongside diminished activity of catechol-O-methyltransferase (COMT), an enzyme that metabolizes catecholamines. The authors found that acute pharmacologic inhibition of COMT in rodents produces hypersensitivity to mechanical and thermal stimuli via β-adrenergic receptor (βAR) activation. The contribution of distinct βAR populations to the development of persistent pain linked to abnormalities in catecholamine signaling requires further investigation. Here, the authors sought to determine the contribution of peripheral, spinal, and supraspinal βARs to persistent COMT-dependent pain. They implanted osmotic pumps to deliver the COMT inhibitor OR486 (Tocris, USA) for 2 weeks. Behavioral responses to mechanical and thermal stimuli were evaluated before and every other day after pump implantation. The site of action was evaluated in adrenalectomized rats receiving sustained OR486 or in intact rats receiving sustained βAR antagonists peripherally, spinally, or supraspinally alongside OR486. The authors found that male (N = 6) and female (N = 6) rats receiving sustained OR486 exhibited decreased paw withdrawal thresholds (control 5.74 ± 0.24 vs. OR486 1.54 ± 0.08, mean ± SEM) and increased paw withdrawal frequency to mechanical stimuli (control 4.80 ± 0.22 vs. OR486 8.10 ± 0.13) and decreased paw withdrawal latency to thermal heat (control 9.69 ± 0.23 vs. OR486 5.91 ± 0.11). In contrast, adrenalectomized rats (N = 12) failed to develop OR486-induced hypersensitivity. Furthermore, peripheral (N = 9), but not spinal (N = 4) or supraspinal (N = 4), administration of the nonselective βAR antagonist propranolol, the β2AR antagonist ICI-118,511, or the β3AR antagonist SR59230A blocked the development of OR486-induced hypersensitivity. Peripheral adrenergic input is necessary for the development of persistent COMT-dependent pain, and peripherally-acting βAR antagonists may benefit chronic pain patients.

Single Prazosin Infusion in Prelimbic Cortex Fosters Extinction of Amphetamine-Induced Conditioned Place Preference.

PubMed

Latagliata, Emanuele C; Lo Iacono, Luisa; Chiacchierini, Giulia; Sancandi, Marco; Rava, Alessandro; Oliva, Valeria; Puglisi-Allegra, Stefano

2017-01-01

Exposure to drug-associated cues to induce extinction is a useful strategy to contrast cue-induced drug seeking. Norepinephrine (NE) transmission in medial prefrontal cortex has a role in the acquisition and extinction of conditioned place preference induced by amphetamine. We have reported recently that NE in prelimbic cortex delays extinction of amphetamine-induced conditioned place preference (CPP). A potential involvement of α1-adrenergic receptors in the extinction of appetitive conditioned response has been also suggested, although their role in prelimbic cortex has not been yet fully investigated. Here, we investigated the effects of the α1-adrenergic receptor antagonist prazosin infusion in the prelimbic cortex of C57BL/6J mice on expression and extinction of amphetamine-induced CPP. Acute prelimbic prazosin did not affect expression of amphetamine-induced CPP on the day of infusion, while in subsequent days it produced a clear-cut advance of extinction of preference for the compartment previously paired with amphetamine (Conditioned stimulus, CS). Moreover, prazosin-treated mice that had extinguished CS preference showed increased mRNA expression of brain-derived neurotrophic factor ( BDNF ) and post-synaptic density 95 ( PSD-95 ) in the nucleus accumbens shell or core, respectively, thus suggesting that prelimbic α1-adrenergic receptor blockade triggers neural adaptations in subcortical areas that could contribute to the extinction of cue-induced drug-seeking behavior. These results show that the pharmacological blockade of α1-adrenergic receptors in prelimbic cortex by a single infusion is able to induce extinction of amphetamine-induced CPP long before control (vehicle) animals, an effect depending on contingent exposure to retrieval, since if infused far from or after reactivation it did not affect preference. Moreover, they suggest strongly that the behavioral effects depend on post-treatment neuroplasticity changes in corticolimbic network, triggered by a possible "priming" effect of prazosin, and point to a potential therapeutic power of the antagonist for maladaptive memories.

Hypothermic and antipyretic effects of ACTH (1-24) and alpha-melanotropin in guinea-pigs

NASA Technical Reports Server (NTRS)

Kandasamy, S. B.; Williams, B. A.

1984-01-01

Intracerebroventricular administration of adrenocorticotropin (ACTH 1-24) and alpha-melanotropin (alpha-MSH), peptides which occur naturally in brain induced dose-related hypothermia in guinea-pigs at room temperature (21 C) and also produced greater hypothermia at low (10 C) ambient temperature. However, when the experiments were repeated in a warm (30 C) environment, no effect on body temperature was observed. These results indicate that the peptides did not reduce the central set-point of temperature control. The hypothermia induced by ACTH and alpha-MSH was not mediated via histamine H1- or H2-receptors and serotonin since the H1-receptor antagonist, mepyramine, the H2-receptor antagonist, cimetidine, and the serotonin antagonist, methysergide, had no antagonistic effects. The peptides were antipyretic since they reduced pyrogen-induced-fever and hyperthermia due to prostaglandin E2, norepinephrine and dibutyryl cAMP, at a dose which did not affect normal body temperature. The powerful central effects of these peptides on normal body temperature, fever and hyperthermia, together with their presence of the brain regions important to temperature control, suggest that they participate in thermoregulation.

CD86 and beta2-adrenergic receptor signaling pathways, respectively, increase Oct-2 and OCA-B Expression and binding to the 3'-IgH enhancer in B cells.

PubMed

Podojil, Joseph R; Kin, Nicholas W; Sanders, Virginia M

2004-05-28

Stimulation of CD86 (formerly known as B7-2) and/or the beta2-adrenergic receptor on a CD40 ligand/interleukin-4-activated B cell increased the rate of mature IgG1 transcription. To identify the mechanism responsible for this effect, we determined whether CD86 and/or beta2-adrenergic receptor stimulation regulated transcription factor expression and binding to the 3'-IgH enhancer in vitro and in vivo. We showed that CD86 stimulation increased the nuclear localization of NF-kappaB1 (p50) and phosphorylated RelA (p65) and increased Oct-2 expression and binding to the 3'-IgH enhancer, in a protein kinase C-dependent manner. These effects were lost when CD86-deficient or NF-kappaB1-deficient B cells were used. CD86 stimulation also increased the level of IkappaB-alpha phosphorylation but in a protein kinase C-independent manner. Beta2-adrenergic receptor stimulation increased CREB phosphorylation, OCA-B expression, and OCA-B binding to the 3'-IgH enhancer in a protein kinase A-dependent manner, an effect lost when beta2-adrenergic receptor-deficient B cells were used. Also, the beta2-adrenergic receptor-induced increase in the level of mature IgG1 transcript was lost when OCA-B-deficient B cells were used. These data are the first to show that CD86 stimulation up-regulates the expression of the transcription factor Oct-2 in a protein kinase C- and NF-kappaB1-dependent manner, and that beta2-adrenergic receptor stimulation up-regulates the expression of the coactivator OCA-B in a protein kinase A-dependent manner to cooperate with Oct-2 binding to the 3'-IgH enhancer.

Functional characterization of the beta-adrenergic receptor subtypes expressed by CA1 pyramidal cells in the rat hippocampus.

PubMed

Hillman, Kristin L; Doze, Van A; Porter, James E

2005-08-01

Recent studies have demonstrated that activation of the beta-adrenergic receptor (AR) using the selective beta-AR agonist isoproterenol (ISO) facilitates pyramidal cell long-term potentiation in the cornu ammonis 1 (CA1) region of the rat hippocampus. We have previously analyzed beta-AR genomic expression patterns of 17 CA1 pyramidal cells using single cell reverse transcription-polymerase chain reaction, demonstrating that all samples expressed the beta2-AR transcript, with four of the 17 cells additionally expressing mRNA for the beta1-AR subtype. However, it has not been determined which beta-AR subtypes are functionally expressed in CA1 for these same pyramidal neurons. Using cell-attached recordings, we tested the ability of ISO to increase pyramidal cell action potential (AP) frequency in the presence of subtype-selective beta-AR antagonists. ICI-118,551 [(+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol] and butoxamine [alpha-[1-(t-butylamino)ethyl]-2,5-dimethoxybenzyl alcohol) hydrochloride], agents that selectively block the beta2-AR, produced significant parallel rightward shifts in the concentration-response curves for ISO. From these curves, apparent equilibrium dissociation constant (K(b)) values of 0.3 nM for ICI-118,551 and 355 nM for butoxamine were calculated using Schild regression analysis. Conversely, effective concentrations of the selective beta1-AR antagonists CGP 20712A [(+/-)-2-hydroxy-5-[2-([2-hydroxy-3-(4-[1-methyl-4-(trifluoromethyl)-1H-imidazol-2-yl]phenoxy)propyl]amino)ethoxy]-benzamide methanesulfonate] and atenolol [4-[2'-hydroxy-3'-(isopropyl-amino)propoxy]phenylacetamide] did not significantly affect the pyramidal cell response to ISO. However, at higher concentrations, atenolol significantly decreased the potency for ISO-mediated AP frequencies. From these curves, an apparent atenolol K(b) value of 3162 nM was calculated. This pharmacological profile for subtype-selective beta-AR antagonists indicates that beta2-AR activation is mediating the increased AP frequency. Knowledge of functional AR expression in CA1 pyramidal neurons will aid future long-term potentiation studies by allowing selective manipulation of specific beta-AR subtypes.

Effects of β-adrenergic receptor drugs on embryonic ventricular cell proliferation and differentiation and their impact on donor cell transplantation.

PubMed

Feridooni, Tiam; Hotchkiss, Adam; Baguma-Nibasheka, Mark; Zhang, Feixiong; Allen, Brittney; Chinni, Sarita; Pasumarthi, Kishore B S

2017-05-01

β-Adrenergic receptors (β-ARs) and catecholamines are present in rodents as early as embryonic day (E)10.5. However, it is not known whether β-AR signaling plays any role in the proliferation and differentiation of ventricular cells in the embryonic heart. Here, we characterized expression profiles of β-AR subtypes and established dose-response curves for the nonselective β-AR agonist isoproterenol (ISO) in the developing mouse ventricular cells. Furthermore, we investigated the effects of ISO on cell cycle activity and differentiation of cultured E11.5 ventricular cells. ISO treatment significantly reduced tritiated thymidine incorporation and cell proliferation rates in both cardiac progenitor cell and cardiomyocyte populations. The ISO-mediated effects on DNA synthesis could be abolished by cotreatment of E11.5 cultures with either metoprolol (a β 1 -AR antagonist) or ICI-118,551 (a β 2 -AR antagonist). In contrast, ISO-mediated effects on cell proliferation could be abolished only by metoprolol. Furthermore, ISO treatment significantly increased the percentage of differentiated cardiomyocytes compared with that in control cultures. Additional experiments revealed that β-AR stimulation leads to downregulation of Erk and Akt phosphorylation followed by significant decreases in cyclin D1 and cyclin-dependent kinase 4 levels in E11.5 ventricular cells. Consistent with in vitro results, we found that chronic stimulation of recipient mice with ISO after intracardiac cell transplantation significantly decreased graft size, whereas metoprolol protected grafts from the inhibitory effects of systemic catecholamines. Collectively, these results underscore the effects of β-AR signaling in cardiac development as well as graft expansion after cell transplantation. NEW & NOTEWORTHY β-Adrenergic receptor (β-AR) stimulation can decrease the proliferation of embryonic ventricular cells in vitro and reduce the graft size after intracardiac cell transplantation. In contrast, β 1 -AR antagonists can abrogate the antiproliferative effects mediated by β-AR stimulation and increase graft size. These results highlight potential interactions between adrenergic drugs and cell transplantation. Copyright © 2017 the American Physiological Society.

Catecholaminergic consolidation of motor cortical neuroplasticity in humans.

PubMed

Nitsche, Michael A; Grundey, Jessica; Liebetanz, David; Lang, Nicolas; Tergau, Frithjof; Paulus, Walter

2004-11-01

Amphetamine, a catecholaminergic re-uptake-blocker, is able to improve neuroplastic mechanisms in humans. However, so far not much is known about the underlying physiological mechanisms. Here, we study the impact of amphetamine on NMDA receptor-dependent long-lasting excitability modifications in the human motor cortex elicited by weak transcranial direct current stimulation (tDCS). Amphetamine significantly enhanced and prolonged increases in anodal, tDCS-induced, long-lasting excitability. Under amphetamine premedication, anodal tDCS resulted in an enhancement of excitability which lasted until the morning after tDCS, compared to approximately 1 h in the placebo condition. Prolongation of the excitability enhancement was most pronounced for long-term effects; the duration of short-term excitability enhancement was only slightly increased. Since the additional application of the NMDA receptor antagonist dextromethorphane blocked any enhancement of tDCS-driven excitability under amphetamine, we conclude that amphetamine consolidates the tDCS-induced neuroplastic effects, but does not initiate them. The fact that propanolol, a beta-adrenergic antagonist, diminished the duration of the tDCS-generated after-effects suggests that adrenergic receptors play a certain role in the consolidation of NMDA receptor-dependent motor cortical excitability modifications in humans. This result may enable researchers to optimize neuroplastic processes in the human brain on the rational basis of purpose-designed pharmacological interventions.

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

PubMed

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

2015-11-15

Graft-versus-host disease (GVHD) is the major complication of allogeneic hematopoietic cell transplantation, a potentially curative therapy for hematologic diseases. It has long been thought that murine bone marrow-derived T cells do not mediate severe GVHD because of their quantity and/or phenotype. During the course of experiments testing the impact of housing temperatures on GVHD, we discovered that this apparent resistance is a function of the relatively cool ambient housing temperature. Murine bone marrow-derived T cells have the ability to mediate severe GVHD in mice housed at a thermoneutral temperature. Specifically, mice housed at Institutional Animal Care and Use Committee-mandated, cool standard temperatures (∼ 22°C) are more resistant to developing GVHD than are mice housed at thermoneutral temperatures (∼ 30°C). We learned that the mechanism underlying this housing-dependent immunosuppression is associated with increased norepinephrine production and excessive signaling through β-adrenergic receptor signaling, which is increased when mice are cold stressed. Treatment of mice housed at 22°C with a β2-adrenergic antagonist reverses the norepinephrine-driven suppression of GVHD and yields similar disease to mice housed at 30°C. Conversely, administering a β2-adrenergic agonist decreases GVHD in mice housed at 30°C. In further mechanistic studies using β2-adrenergic receptor-deficient (β2-AR(-/-)) mice, we found that it is host cell β2-AR signaling that is essential for decreasing GVHD. These data reveal how baseline levels of β-adrenergic receptor signaling can influence murine GVHD and point to the feasibility of manipulation of β2-AR signaling to ameliorate GVHD in the clinical setting. Copyright © 2015 by The American Association of Immunologists, Inc.

Current and Novel Therapeutic Options for Irritable Bowel Syndrome Management

PubMed Central

Camilleri, Michael; Andresen, Viola

2009-01-01

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder affecting up to 3-15% of the general population in western countries. It is characterized by unexplained abdominal pain, discomfort, and bloating in association with altered bowel habits. The pathophysiology of IBS is multifactorial involving disturbances of the brain-gut-axis. The pathophysiology provides the rationale for pharmacotherapy: abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction, and mucosal immune activation. Understanding the mechanisms, and their mediators or modulators including neurotransmitters and receptors have led to several therapeutic approaches including agents acting on the serotonin receptor or serotonin transporter system, antidepressants, novel selective anticholinergics, α-adrenergic agonists, opioid agents, cholecystokinin-antagonists, neurokinin-antagonists, somatostatin receptor agonists, corticotropin releasing factor antagonists, chloride-channel activators, guanylate-cyclase-c agonists, melatonin, atypical benzodiazepines, antibiotics, immune modulators and probiotics. The mechanisms and current evidence regarding efficacy of these agents are reviewed. PMID:19665953

Attenuation of alpha2A-adrenergic receptor expression in neonatal rat brain by RNA interference or antisense oligonucleotide reduced anxiety in adulthood.

PubMed

Shishkina, G T; Kalinina, T S; Dygalo, N N

2004-01-01

Brain alpha2-adrenergic receptors (alpha2-ARs) have been implicated in the regulation of anxiety, which is associated with stress. Environmental treatments during neonatal development could modulate the level of brain alpha2-AR expression and alter anxiety in adults, suggesting possible involvement of these receptors in early-life programming of anxiety state. The present study was undertaken to determine whether the reduction of the expression of A subtype of these receptors most abundant in the neonatal brain affects anxiety-related behavior in adulthood. We attenuated the expression of alpha2A-ARs during neonatal life by two different sequence specific approaches, antisense technology and RNA interference. Treatment of rats with the antisense oligodeoxynucleotide or short interfering RNA (siRNA) against alpha2A-ARs on the days 2-4 of their life, produced a marked acute decrease in the levels of both alpha2A-AR mRNA and [3H]RX821002 binding sites in the brainstem into which drugs were injected. The decrease of alpha2A-AR expression in the neonatal brainstem influenced the development of this receptor system in the brain regions as evidenced by the increased number of [3H]RX821002 binding sites in the hypothalamus of adult animals with both neonatal alpha2A-AR knockdown treatments; also in the frontal cortex of antisense-treated, and in the hippocampus of siRNA-treated adult rats. These adult animals also demonstrated a decreased anxiety in the elevated plus-maze as evidenced by an increased number of the open arm entries, greater proportion of time spent in the open arms, and more than a two-fold increase in the number of exploratory head dips. The results provide the first evidence that the reduction in the brain expression of a gene encoding for alpha2A-AR during neonatal life led to the long-term neurochemical and behavioral alterations. The data suggests that alterations in the expression of the receptor-specific gene during critical periods of brain development may be involved in early-life programming of anxiety-related behavior.

Alfuzosin and symptoms of chronic prostatitis-chronic pelvic pain syndrome.

PubMed

Nickel, J Curtis; Krieger, John N; McNaughton-Collins, Mary; Anderson, Rodney U; Pontari, Michel; Shoskes, Daniel A; Litwin, Mark S; Alexander, Richard B; White, Paige C; Berger, Richard; Nadler, Robert; O'Leary, Michael; Liong, Men Long; Zeitlin, Scott; Chuai, Shannon; Landis, J Richard; Kusek, John W; Nyberg, Leroy M; Schaeffer, Anthony J

2008-12-18

In men with chronic prostatitis-chronic pelvic pain syndrome, treatment with alpha-adrenergic receptor blockers early in the course of the disorder has been reported to be effective in some, but not all, relatively small randomized trials. We conducted a multicenter, randomized, double-blind, placebo-controlled trial to evaluate the efficacy of alfuzosin, an alpha-adrenergic receptor blocker, in reducing symptoms in men with chronic prostatitis-chronic pelvic pain syndrome. Participation in the study required diagnosis of the condition within the preceding 2 years and no previous treatment with an alpha-adrenergic receptor blocker. Men were randomly assigned to treatment for 12 weeks with either 10 mg of alfuzosin per day or placebo. The primary outcome was a reduction of at least 4 points (from baseline to 12 weeks) in the score on the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) (range, 0 to 43; higher scores indicate more severe symptoms). A 4-point decrease is the minimal clinically significant difference in the score. A total of 272 eligible participants underwent randomization, and in both study groups, 49.3% of participants had a decrease of at least 4 points in their total NIH-CPSI score (rate difference associated with alfuzosin, 0.1%; 95% confidence interval, -11.2 to 11.0; P=0.99). In addition, a global response assessment showed similar response rates at 12 weeks: 33.6% in the placebo group and 34.8% in the alfuzosin group (P=0.90). The rates of adverse events in the two groups were also similar. Our findings do not support the use of alfuzosin to reduce the symptoms of chronic prostatitis-chronic pelvic pain syndrome in men who have not received prior treatment with an alpha-blocker. (ClinicalTrials.gov number, NCT00103402.) 2008 Massachusetts Medical Society

Alfuzosin and Symptoms of Chronic Prostatitis–Chronic Pelvic Pain Syndrome

PubMed Central

Nickel, J. Curtis; Krieger, John N.; McNaughton-Collins, Mary; Anderson, Rodney U.; Pontari, Michel; Shoskes, Daniel A.; Litwin, Mark S.; Alexander, Richard B.; White, Paige C.; Berger, Richard; Nadler, Robert; O'Leary, Michael; Liong, Men Long; Zeitlin, Scott; Chuai, Shannon; Landis, J. Richard; Kusek, John W.; Nyberg, Leroy M.; Schaeffer, Anthony J.

2009-01-01

Background In men with chronic prostatitis–chronic pelvic pain syndrome, treatment with alpha-adrenergic receptor blockers early in the course of the disorder has been reported to be effective in some, but not all, relatively small randomized trials. Methods We conducted a multicenter, randomized, double-blind, placebo-controlled trial to evaluate the efficacy of alfuzosin, an alpha-adrenergic receptor blocker, in reducing symptoms in men with chronic prostatitis–chronic pelvic pain syndrome. Participation in the study required diagnosis of the condition within the preceding 2 years and no previous treatment with an alpha-adrenergic receptor blocker. Men were randomly assigned to treatment for 12 weeks with either 10 mg of alfuzosin per day or placebo. The primary outcome was a reduction of at least 4 points (from baseline to 12 weeks) in the score on the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) (range, 0 to 43; higher scores indicate more severe symptoms). A 4-point decrease is the minimal clinically significant difference in the score. Results A total of 272 eligible participants underwent randomization, and in both study groups, 49.3% of participants had a decrease of at least 4 points in their total NIH-CPSI score (rate difference associated with alfuzosin, 0.1%; 95% confidence interval, −11.2 to 11.0; P = 0.99). In addition, a global response assessment showed similar response rates at 12 weeks: 33.6% in the placebo group and 34.8% in the alfuzosin group (P = 0.90). The rates of adverse events in the two groups were also similar. Conclusions Our findings do not support the use of alfuzosin to reduce the symptoms of chronic prostatitis–chronic pelvic pain syndrome in men who have not received prior treatment with an alpha-blocker. PMID:19092152

Similarity- and Substructure-Based Development of β2-Adrenergic Receptor Ligands Based on Unusual Scaffolds

PubMed Central

2017-01-01

The β2-adrenergic receptor (β2AR) is a G protein-coupled receptor (GPCR) and a well-explored target. Here, we report the discovery of 13 ligands, ten of which are novel, of this particular GPCR. They have been identified by similarity- and substructure-based searches using multiple ligands, which were described in an earlier study, as starting points. Of note, two of the molecules used as queries here distinguish themselves from other β2AR antagonists by their unique scaffold. The molecules described in this work allow us to explore the ligand space around the previously reported molecules in greater detail, leading to insights into their structure–activity relationship. We also report experimental binding and selectivity data and putative binding modes for the novel molecules. PMID:28523097

Involvement of α(2)-adrenergic receptor in the regulation of the blood glucose level induced by immobilization stress.

PubMed

Kang, Yu-Jung; Sim, Yun-Beom; Park, Soo-Hyun; Sharma, Naveen; Suh, Hong-Won

2015-01-01

The blood glucose profiles were characterized after mice were forced into immobilization stress with various exposure durations. The blood glucose level was significantly enhanced by immobilization stress for 30 min or 1 h, respectively. On the other hand, the blood glucose level was not affected in the groups which were forced into immobilization stress for 2 or 4 h. We further examined the effect of yohimbine (an α2-adrenergic receptor antagonist) administered systemically or centrally in the immobilization stress model. Mice were pretreated intraperitoneally (i.p.; from 0.5 to 5 mg/kg), intracerebroventricularly (i.c.v.; from 1 to 10 µg/5 µl), or intrathecally (i.t.; from 1 to 10 µg/5 µl) with yohimbine for 10 min and then, forced into immobilization stress for 30 min. The blood glucose level was measured right after immobilization stress. We found that up-regulation of the blood glucose level induced by immobilization stress was abolished by i.p. pretreatment with yohimbine. And the immobilization stress-induced blood glucose level was not inhibited by i.c.v. or i.t. pretreatment with yohimbine at a lower dose (1 µg/5 µl). However, immobilization stress-induced blood glucose level was significantly inhibited by i.c.v. or i.t. pretreatment with yohimbine at higher doses (5 and 10 µg/5 µl). In addition, the i.p. (5 mg/kg), i.c.v. (10 µg/5 µl), or i.t. (10 µg/5 µl) pretreatment with yohimbine reduced hypothalamic glucose transporter 4 expression. The involvement of α2-adrenergic receptor in regulation of immobilization stress- induced blood glucose level was further confirmed by the i.p, i.c.v, or i.t pretreatment with idazoxan, another specific α2-adrenergic receptor antagonist. Finally, i.p., i.c.v., or i.t. pretreatment with yohimbine attenuated the blood glucose level in D-glucose-fed model. We suggest that α2-adrenergic receptors located at the peripheral, the brain and the spinal cord play important roles in the up-regulation of the blood glucose level in immobilization stress.

Antinociceptive synergism of MD-354 and clonidine. Part II. The alpha-adrenoceptor component.

PubMed

Young, Shawquia; Vainio, Minna; Scheinin, Mika; Dukat, Małgorzata

2010-08-01

Previously, we reported that antinociceptive synergism of a 5-HT(3)/alpha(2)-adrenoceptor ligand MD-354 (m-chlorophenylguanidine) and clonidine combination occurs, in part, through a 5-HT(3) receptor antagonist mechanism. In the present investigation, a possible role for alpha(2)-adrenoceptors was examined. Mechanistic studies using yohimbine (a subtype non-selective alpha(2)-adrenoceptor antagonist), BRL 44408 (a preferential alpha(2A)-adrenoceptor antagonist) and imiloxan (a preferential alpha(2B/C)-adrenoceptor antagonist) on the antinociceptive actions of a MD-354/clonidine combination were conducted. Subcutaneous pre-treatment with all three antagonists inhibited the antinociceptive synergism of MD-354 and clonidine in the mouse tail-flick assay in a dose-dependent manner (AD(50) = 0.33, 2.1, and 0.17 mg/kg, respectively). Enhancement of clonidine antinociception by MD-354 did not potentiate clonidine's locomotor suppressant activity in a mouse locomotor assay. When [ethyl-3H]RS-79948-197 was used as radioligand, MD-354 displayed almost equal affinity to alpha(2A)- and alpha(2B)-adrenoceptors (K(i) = 110 and 220 nM) and showed lower affinity at alpha(2C)-adrenoceptors (K(i) = 4,700 nM). MD-354 had no subtype-selectivity for the alpha(2)-adrenoceptor subtypes as an antagonist in functional [35S]GTPgammaS binding assays. MD-354 was a weak partial agonist at alpha(2A)-adrenoceptors. Overall, in addition to the 5-HT(3) receptor component, the present investigation found MD-354 to be a weak partial alpha(2A)-adrenoceptor agonist that enhances clonidine's thermal antinociceptive actions through an alpha(2)-adrenoceptor-mediated mechanism without augmenting sedation.

Systemic administration of guanfacine improves food-motivated impulsive choice behavior primarily via direct stimulation of postsynaptic α2A-adrenergic receptors in rats.

PubMed

Nishitomi, Kouhei; Yano, Koji; Kobayashi, Mika; Jino, Kohei; Kano, Takuya; Horiguchi, Naotaka; Shinohara, Shunji; Hasegawa, Minoru

2018-06-01

Impulsive choice behavior, which can be assessed using the delay discounting task, is a characteristic of various psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). Guanfacine is a selective α 2A -adrenergic receptor agonist that is clinically effective in treating ADHD. However, there is no clear evidence that systemic guanfacine administration reduces impulsive choice behavior in the delay discounting task in rats. In the present study, we examined the effect of systemic guanfacine administration on food-motivated impulsive choice behavior in rats and the neuronal mechanism underlying this effect. Repeated administration of either guanfacine, methylphenidate, or atomoxetine significantly enhanced impulse control, increasing the number of times the rats chose a large but delayed reward in a dose-dependent manner. The effect of guanfacine was significantly blocked by pretreatment with an α 2A -adrenergic receptor antagonist. Furthermore, the effect of guanfacine remained unaffected in rats pretreated with a selective noradrenergic neurotoxin, consistent with a post-synaptic action. In contrast, the effect of atomoxetine on impulsive choice behavior was attenuated by pretreatment with the noradrenergic neurotoxin. These results provide the first evidence that systemically administered guanfacine reduces impulsive choice behavior in rats and that direct stimulation of postsynaptic, rather than presynaptic, α 2A -adrenergic receptors is involved in this effect. Copyright © 2018 Elsevier B.V. All rights reserved.

Adrenaline stimulates the proliferation and migration of mesenchymal stem cells towards the LPS-induced lung injury.

PubMed

Wu, Xiaodan; Wang, Zhiming; Qian, Mengjia; Wang, Lingyan; Bai, Chunxue; Wang, Xiangdong

2014-08-01

Bone marrow-derived mesenchymal stem cells (BMSCs) could modulate inflammation in experimental lung injury. On the other hand, adrenergic receptor agonists could increase DNA synthesis of stem cells. Therefore, we investigated the therapeutic role of adrenaline-stimulated BMSCs on lipopolysaccharide (LPS)-induced lung injury. BMSCs were cultured with adrenergic receptor agonists or antagonists. Suspensions of lung cells or sliced lung tissue from animals with or without LPS-induced injury were co-cultured with BMSCs. LPS-stimulated alveolar macrophages were co-cultured with BMSCs (with adrenaline stimulation or not) in Transwell for 6 hrs. A preliminary animal experiment was conducted to validate the findings in ex vivo study. We found that adrenaline at 10 μM enhanced proliferation of BMSCs through both α- and β-adrenergic receptors. Adrenaline promoted the migration of BMSCs towards LPS-injured lung cells or lung tissue. Adrenaline-stimulated BMSCs decreased the inflammation of LPS-stimulated macrophages, probably through the expression and secretion of several paracrine factors. Adrenaline reduced the extent of injury in LPS-injured rats. Our data indicate that adrenaline-stimulated BMSCs might contribute to the prevention from acute lung injury through the activation of adrenergic receptors, promotion of proliferation and migration towards injured lung, and modulation of inflammation. © 2014 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Methylphenidate and Atomoxetine Enhance Prefrontal Function through alpha[subscript 2]-Adrenergic and Dopamine D[subscript 1] Receptors

ERIC Educational Resources Information Center

Gamo, Nao J.; Wang, Min; Arnsten, Amy F. T.

2010-01-01

Objective: This study examined the effects of the attention-deficit/hyperactivity disorder treatments, methylphenidate (MPH) and atomoxetine (ATM), on prefrontal cortex (PFC) function in monkeys and explored the receptor mechanisms underlying enhancement of PFC function at the behavioral and cellular levels. Method: Monkeys performed a working…

Enhanced Noradrenergic Activity Potentiates Fear Memory Consolidation and Reconsolidation by Differentially Recruiting alpha1- and beta-Adrenergic Receptors

ERIC Educational Resources Information Center

Gazarini, Lucas; Stern, Cristina A. Jark; Carobrez, Antonio P.; Bertoglio, Leandro J.

2013-01-01

Consolidation and reconsolidation are phases of memory stabilization that diverge slightly. Noradrenaline is known to influence both processes, but the relative contribution of alpha1- and beta-adrenoceptors is unclear. The present study sought to investigate this matter by comparing their recruitment to consolidate and/or reconsolidate a…

Alpha 1-adrenergic blockade does not alter control of skin blood flow during exercise.

PubMed

Kenney, W L; Tankersley, C G; Newswanger, D L; Puhl, S M

1991-03-01

Human skin blood flow (SkBF) is controlled by both an alpha-adrenergic vasoconstrictor system and an active vasodilator system. During upright dynamic exercise, SkBF increases linearly with increasing body core temperature (Tc) until higher (i.e., greater than 38 degrees C) Tcs, beyond which little further increase in SkBF occurs. To examine the role of the two efferent control arms in this attenuated SkBF rise, we tested nine men (aged 25-53 yr) with and without (placebo) orally administered prazosin HCl (an alpha 1-adrenergic antagonist) during 1 h of moderate cycle exercise (100 W) in a warm (36 degrees C, 45% relative humidity) environment. Blockade of reflex vasoconstriction was verified via a cold challenge. During exercise, mean arterial pressure (MAP, brachial auscultation) was significantly lower (P less than 0.03) and heart rate significantly higher (P less than 0.02) during the prazosin trials; plasma catecholamine concentrations were unaffected. Neither esophageal temperature (Tes) nor mean skin temperature was affected by the drug during exercise. Forearm vascular conductance (FVC) was calculated from forearm blood flow (FBF, venous occlusion plethysmography) and MAP (FVC = FBF/MAP). FVC plotted as a function of time or Tes resulted in coincident response patterns for the placebo and prazosin treatments, reaching a plateau at a Tes of about 38 degrees C. The responses of the older men were not selectively altered by prazosin treatment, indicating that the lower FBF responses previously seen in older subjects during exercise in the heat does not appear to be the result of an increased alpha 1-adrenergic tone.(ABSTRACT TRUNCATED AT 250 WORDS)

[Intraoperative floppy iris syndrome].

PubMed

Mazal, Z

2007-04-01

In the year 2005, Chang and Cambell described unusual reaction of the iris during the cataract surgery in patients treated with tamsulosine. This was named as IFIS, an acronym for the Intraoperative Floppy Iris Syndrome. In its advanced stage, the syndrome is characterized by insufficient mydfiasis before the surgery, narrowing of the pupil during the surgery, its impossible dilatation during the surgery by means of stretching, unusual elasticity of the pupilar margin, surging and fluttering iris with tendency to prolapse. The same manifestations we observed in our patients and we confirm the direct connection with tamsulosine hydrochloride treatment. Tamsulosine is the antagonist of alpha 1A adrenergic receptors whose are present, except in the smooth musculature of the prostate gland and the urinary bladder, in the iris dilator as well. At the same time we observed this syndrome rarely in some patients not using tamsulosine. In most cases, these patients were treated with antipsychotic drugs.

Alpha-adrenoceptor blockade modifies neurally induced atrial arrhythmias.

PubMed

Richer, Louis-Philippe; Vinet, Alain; Kus, Teresa; Cardinal, René; Ardell, Jeffrey L; Armour, John Andrew

2008-10-01

Our objective was to determine whether neuronally induced atrial arrhythmias can be modified by alpha-adrenergic receptor blockade. In 30 anesthetized dogs, trains of five electrical stimuli (1 mA; 1 ms) were delivered immediately after the P wave of the ECG to mediastinal nerves associated with the superior vena cava. Regional atrial electrical events were monitored with 191 atrial unipolar electrodes. Mediastinal nerve sites were identified that reproducibly initiated atrial arrhythmias. These sites were then restimulated following 1 h (time control, n = 6), or the intravenous administration of naftopidil (alpha(1)-adrenergic blocker: 0.2 mg/kg, n = 6), yohimbine (alpha(2)-adrenergic blocker: 1 mg/kg, n = 6) or both (n = 8). A ganglionic blocker (hexamethonium: 1 mg/kg) was tested in four dogs. Stimulation of mediastinal nerves sites consistently elicited atrial tachyarrhythmias. Repeat stimulation after 1 h in the time-control group exerted a 19% decrease of the sites still able to induce atrial tachyarrhythmias. Hexamethonium inactivated 78% of the previously active sites. Combined alpha-adrenoceptor blockade inactivated 72% of the previously active sites. Bradycardia responses induced by mediastinal nerve stimulation were blunted by hexamethonium, but not by alpha(1,2)-adrenergic blockade. Naftopidil or yohimbine alone eliminated atrial arrhythmia induction from 31% and 34% of the sites (similar to time control). We conclude that heterogeneous activation of the intrinsic cardiac nervous system results in atrial arrhythmias that involve intrinsic cardiac neuronal alpha-adrenoceptors. In contrast to the global suppression exerted by hexamethonium, we conclude that alpha-adrenoceptor blockade targets intrinsic cardiac local circuit neurons involved in arrhythmia formation and not the flow-through efferent projections of the cardiac nervous system.

G Protein-Coupled Estrogen Receptor (GPER) Agonist Dual Binding Mode Analyses toward Understanding of its Activation Mechanism: A Comparative Homology Modeling Approach.

PubMed

Arnatt, Christopher K; Zhang, Yan

2013-07-01

G protein-coupled estrogen receptor (GPER) has been shown to be important in several disease states such as estrogen sensitive cancers. While several selective ligands have been identified for the receptor, little is known about how they interact with GPER and how their structures influence their activity. Specifically, within one series of ligands, whose structure varied only at one position, the replacement of a hydrogen atom with an acetyl group changed a potent antagonist into a potent agonist. In this study, two GPER homology models were constructed based on the x-ray crystal structures of both the active and inactive β 2 -adrenergic receptors (β 2 AR) in an effort to characterize the differences of binding modes between agonists and antagonists to the receptor, and to understand their activity in relation to their structures. The knowledge attained in this study is expected to provide valuable information on GPER ligands structure activity relationship to benefit future rational design of potent agonists and antagonists of the receptor for potential therapeutic applications.

G Protein-Coupled Estrogen Receptor (GPER) Agonist Dual Binding Mode Analyses toward Understanding of its Activation Mechanism: A Comparative Homology Modeling Approach

PubMed Central

Arnatt, Christopher K.; Zhang, Yan

2015-01-01

G protein-coupled estrogen receptor (GPER) has been shown to be important in several disease states such as estrogen sensitive cancers. While several selective ligands have been identified for the receptor, little is known about how they interact with GPER and how their structures influence their activity. Specifically, within one series of ligands, whose structure varied only at one position, the replacement of a hydrogen atom with an acetyl group changed a potent antagonist into a potent agonist. In this study, two GPER homology models were constructed based on the x-ray crystal structures of both the active and inactive β2-adrenergic receptors (β2AR) in an effort to characterize the differences of binding modes between agonists and antagonists to the receptor, and to understand their activity in relation to their structures. The knowledge attained in this study is expected to provide valuable information on GPER ligands structure activity relationship to benefit future rational design of potent agonists and antagonists of the receptor for potential therapeutic applications. PMID:26229572

Reversal of behavioral depression by infusion of an alpha-2 adrenergic agonist into the locus coeruleus.

PubMed

Simson, P G; Weiss, J M; Hoffman, L J; Ambrose, M J

1986-04-01

This experiment demonstrated that behavioral depression produced by exposure of rats to strong uncontrollable shocks could be reversed by infusion of the alpha-2 adrenergic agonist clonidine into the region of the locus coeruleus (LC). A 20-min infusion, through bilateral cannulae, into the locus coeruleus of clonidine, piperoxane (alpha-2 antagonist) or inactive vehicle (0.85% saline), was given beginning 70 min after the animals were removed from the stress situation. The dose and volume of drug given in the infusion (0.16 microgram/microliter, 0.1 microliter/min) had been previously shown to produce effects specific to the locus coeruleus (Weiss, Simson, Hoffman, Ambrose, Cooper and Webster, 1986; Neuropharmacology 25: 367-384). At the conclusion of the infusion, active behavior of animals was measured in a 15-min swim test. Results showed that stressed animals infused with vehicle exhibited significantly less active behavior in the swim test than did non-stressed animals infused with vehicle, thereby showing the usual behavioral depression seen after exposure to an uncontrollable stress. Stressed animals infused with clonidine showed no difference in active behavior in comparison to non-stressed animals infused with vehicle and showed significantly more activity than did the stressed animals infused with vehicle. Stressed animals infused with piperoxane showed no significant difference in activity in comparison to the stressed animals infused with vehicle and were significantly less active than either the non-stressed animals infused with vehicle or the stressed animals infused with clonidine. Thus, infusion into the locus coeruleus of the alpha-2 agonist clonidine, but not the alpha-2 antagonist piperoxane, eliminated behavioral depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical correlates in an animal model of depression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, J.O.

1986-01-01

A valid animal model of depression was used to explore specific adrenergic receptor differences between rats exhibiting aberrant behavior and control groups. Preliminary experiments revealed a distinct upregulation of hippocampal beta-receptors (as compared to other brain regions) in those animals acquiring a response deficit as a result of exposure to inescapable footshock. Concurrent studies using standard receptor binding techniques showed no large changes in the density of alpha-adrenergic, serotonergic, or dopaminergic receptor densities. This led to the hypothesis that the hippocampal beta-receptor in responses deficient animals could be correlated with the behavioral changes seen after exposure to the aversive stimulus.more » Normalization of the behavior through the administration of antidepressants could be expected to reverse the biochemical changes if these are related to the mechanism of action of antidepressant drugs. This study makes three important points: (1) there is a relevant biochemical change in the hippocampus of response deficient rats which occurs in parallel to a well-defined behavior, (2) the biochemical and behavioral changes are normalized by antidepressant treatments exhibiting both serotonergic and adrenergic mechanisms of action, and (3) the mode of action of antidepressants in this model is probably a combination of serotonergic and adrenergic influences modulating the hippocampal beta-receptor. These results are discussed in relation to anatomical and biochemical aspects of antidepressant action.« less

Differential effects of beta-adrenergic receptor blockade in the medial prefrontal cortex during aversive and incidental taste memory formation.

PubMed

Reyes-López, J; Nuñez-Jaramillo, L; Morán-Guel, E; Miranda, M I

2010-08-11

The medial prefrontal cortex (mPFC) is a brain area crucial for memory, attention, and decision making. Specifically, the noradrenergic system in this cortex is involved in aversive learning, as well as in the retrieval of these memories. Some evidence suggests that this area has an important role during taste memory, particularly during conditioned taste aversion (CTA), a model of aversive memory. Despite some previous evidence, there is scarce information about the role of adrenergic receptors in the mPFC during formation of aversive taste memory and appetitive/incidental taste memory. The goal of this research was to evaluate the role of mPFC beta-adrenergic receptors during CTA acquisition/consolidation or CTA retrieval, as well as during incidental taste memory formation using the model of latent inhibition of CTA. The results showed that infusions in the mPFC of the beta-adrenergic antagonist propranolol before CTA acquisition impaired both short- and long-term aversive taste memory formation, and also that propranolol infusions before the memory test impaired CTA retrieval. However, propranolol infusions before pre-exposure to the taste during the latent inhibition procedure had no effect on incidental taste memory acquisition or consolidation. These data indicate that beta-adrenergic receptors in the mPFC have different functions during taste memory formation: they have an important role during aversive taste association as well as during aversive retrieval but not during incidental taste memory formation. Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Antihypertensive drugs.

PubMed

Laurent, Stéphane

2017-10-01

Successful treatment of hypertension is possible with limited side effects given the availability of multiple antihypertensive drug classes. This review describes the various pharmacological classes of antihypertensive drugs, under two major aspects: their mechanisms of action and side effects. The mechanism of action is analysed through a pharmacological approach, i.e. the molecular receptor targets, the various sites along the arterial system, and the extra-arterial sites of action, in order to better understand in which type of hypertension a given pharmacological class of antihypertensive drug is most indicated. In addition, side effects are described and explained through their pharmacological mechanisms, in order to better understand their mechanism of occurrence and in which patients drugs are contra-indicated. This review does not address the effectiveness of monotherapies in large randomized clinical trials and combination therapies, since these are the matters of other articles of the present issue. Five major pharmacological classes of antihypertensive drugs are detailed here: beta-blockers, diuretics, angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, and calcium channel blockers. Four additional pharmacological classes are described in a shorter manner: renin inhibitors, alpha-adrenergic receptor blockers, centrally acting agents, and direct acting vasodilators. Copyright © 2017. Published by Elsevier Ltd.

Silodosin in the treatment of benign prostatic hyperplasia

PubMed Central

Rossi, Maxime; Roumeguère, Thierry

2010-01-01

Benign prostatic hyperplasia (BPH)-associated lower urinary tract symptoms (LUTS) are highly prevalent in older men. Medical therapy is the first-line treatment for LUTS due to BPH. Alpha-adrenergic receptor blockers remain one of the mainstays in the treatment of male LUTS and clinical BPH. They exhibit early onset of efficacy with regard to both symptoms and flow rate improvement, and this is clearly demonstrated in placebo-controlled trials with extensions out to five years. These agents have been shown to prevent symptomatic progression of the disease. The aim of this article is to offer a critical review of the current literature on silodosin, formerly known as KMD-3213, a novel alpha-blocker with unprecedented selectivity for α1A-adrenergic receptors, as compared with both α1B- and α1D -adrenoceptors, exceeding the selectivity of all currently used α1-blockers, and with clinically promising effects. PMID:21116335

Selective blockade by nicergoline of vascular responses elicited by stimulation of alpha 1A-adrenoceptor subtype in the rat.

PubMed

Alvarez-Guerra, M; Bertholom, N; Garay, R P

1999-01-01

The alpha 1-adrenergic blocking activity of nicergoline was re-examined in rats, with a particular emphasis on alpha 1-adrenoceptor subtypes. In pithed rats, nicergoline and prazosin infused at a single small dose (0.5 microgram/kg/min i.v.) produced a substantial and identical shift to the right of the control dose pressor response curve to the specific alpha 1-agonist cirazoline (ED50 = 4.0 +/- 0.1, 4.0 +/- 0.1 and 0.9 +/- 0.01 microgram/kg i.v. for nicergoline, prazosin and vehicle respectively). In the isolated perfused mesenteric vascular bed, nicergoline strongly inhibited the pressor responses elicited by cirazoline, with approximately 40-fold higher potency (pA2 = 11.1 +/- 0.3) than prazosin (pA2 = 9.5 +/- 0.3). Conversely, nicergoline was 20-fold less potent than prazosin to antagonize the contractile effects of cirazoline in isolated endothelium-denuded aorta (pA2 = 8.6 +/- 0.2 and 9.9 +/- 0.2 for nicergoline and prazosin respectively). Pretreatment of mesenteric vascular beds with chloroethylclonidine did not significantly modify nicergoline antagonistic potency (pA2 = 10.6 +/- 0.2). Nicergoline displaced [3H]-prazosin bound to rat forebrain membranes pretreated with chloroethylclonidine (pKi = 9.9 +/- 0.2) at concentrations 60-fold lower than in rat liver membranes (pKi = 8.1 +/- 0.2). Finally, of the nicergoline metabolites studied, lumilysergol acted as a modest alpha 1 antagonist (bromonicotinic acid was devoid of alpha 1 antagonist activity). In conclusion, nicergoline is a potent and selective alpha 1A-adrenoceptor subtype antagonist, an alpha 1-adrenoceptor subtype which is mainly represented in resistance arteries.

Intrahippocampal Infusions of Anisomycin Produce Amnesia: Contribution of Increased Release of Norepinephrine, Dopamine, and Acetylcholine

ERIC Educational Resources Information Center

Qi, Zhenghan; Gold, Paul E.

2009-01-01

Intra-amygdala injections of anisomycin produce large increases in the release of norepinephrine (NE), dopamine (DA), and serotonin in the amygdala. Pretreatment with intra-amygdala injections of the beta-adrenergic receptor antagonist propranolol attenuates anisomycin-induced amnesia without reversing the inhibition of protein synthesis, and…

Treatments for Parkinson disease--past achievements and current clinical needs.

PubMed

Poewe, Werner

2009-02-17

Although idiopathic Parkinson disease (PD) remains the only neurodegenerative disorder for which there are highly effective symptomatic therapies, there are still major unmet needs regarding its long-term management. Although levodopa continues as the gold standard for efficacy, its chronic use is associated with potentially disabling motor complications. Current evidence suggests that these are related to mode of administration, whereby multiple oral doses of levodopa generate pulsatile stimulation of striatal dopamine receptors. Current dopamine agonists, while producing more constant plasma levels, fail to match levodopa's efficacy. Strategies to treat levodopa-related motor complications are only partially effective, rarely abolishing motor fluctuations or dyskinesias. Best results are currently achieved with invasive strategies via subcutaneous (s.c.) or intraduodenal delivery of apomorphine or levodopa, or deep brain stimulation of the subthalamic nucleus. Another area of major unmet medical need is related to nondopaminergic and nonmotor symptoms of PD. Targeting transmitter systems beyond the dopamine system is an interesting approach, both for the motor and nonmotor problems of PD. So far, clinical trial evidence regarding 5-HT agonists, glutamate antagonists, adenosine A(2) antagonists and alpha-adrenergic receptor antagonists, has been inconsistent, but trials with cholinesterase inhibitors and atypical antipsychotics to treat dementia and psychosis, have been successful. However, the ultimate goal of PD medical management is modifying disease progression, thereby delaying the evolution of motor and nonmotor complications of advanced disease. As understanding of preclinical markers for PD develops, there is new hope for neuropreventive strategies to target "at risk" populations before clinical onset of disease.

Ghrelin enhancer, rikkunshito, improves postprandial gastric motor dysfunction in an experimental stress model.

PubMed

Harada, Y; Ro, S; Ochiai, M; Hayashi, K; Hosomi, E; Fujitsuka, N; Hattori, T; Yakabi, K

2015-08-01

Functional dyspepsia (FD) is one of the most common disorders of gastrointestinal (GI) diseases. However, no curable treatment is available for FD because the detailed mechanism of GI dysfunction in stressed conditions remains unclear. We aimed to clarify the association between endogenous acylated ghrelin signaling and gastric motor dysfunction and explore the possibility of a drug with ghrelin signal-enhancing action for FD treatment. Solid gastric emptying (GE) and plasma acylated ghrelin levels were evaluated in an urocortin1 (UCN1) -induced stress model. To clarify the role of acylated ghrelin on GI dysfunction in the model, exogenous acylated ghrelin, an endogenous ghrelin enhancer, rikkunshito, or an α2 -adrenergic receptor (AR) antagonist was administered. Postprandial motor function was investigated using a strain gauge force transducer in a free-moving condition. Exogenous acylated ghrelin supplementation restored UCN1-induced delayed GE. Alpha2 -AR antagonist and rikkunshito inhibited the reduction in plasma acylated ghrelin and GE in the stress model. The action of rikkunshito on delayed GE was blocked by co-administration of the ghrelin receptor antagonist. UCN1 decreased the amplitude of contraction in the antrum while increasing it in the duodenum. The motility index of the antrum but not the duodenum was significantly reduced by UCN1 treatment, which was improved by acylated ghrelin or rikkunshito. The UCN1-induced gastric motility dysfunction was mediated by abnormal acylated ghrelin dynamics. Supplementation of exogenous acylated ghrelin or enhancement of endogenous acylated ghrelin secretion by rikkunshito may be effective in treating functional GI disorders. © 2015 The Authors. Neurogastroenterology & Motility Published by John Wiley & Sons Ltd.

Nefiracetam facilitates hippocampal neurotransmission by a mechanism independent of the piracetam and aniracetam action.

PubMed

Nomura, T; Nishizaki, T

2000-07-07

Nefiracetam, a nootropic (cognition-enhancing) agent, facilitated neurotransmission in the dentate gyrus of rat hippocampal slices in a dose-dependent manner at concentrations ranged from 1 nM to 1 microM, being evident at 60-min washing-out of the drug. The facilitatory action was blocked by the nicotinic acetylcholine (ACh) receptor antagonists, alpha-bungarotoxin and mecamylamine. A similar facilitation was induced by the other nootropic agents, piracetam and aniracetam, but the facilitation was not inhibited by nicotinic ACh receptor antagonists and it did not occlude the potentiation induced by nefiracetam. In the Xenopus oocyte expression systems, nefiracetam potentiated currents through a variety of neuronal nicotinic ACh receptors (alpha 3beta 2, alpha 3beta 4, alpha 4 beta 2, alpha 4 beta 4, and alpha 7) to a different extent. In contrast, neither piracetam nor aniracetam had any potentiating action on alpha 7 receptor currents. While aniracetam delayed the decay time of currents through the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor, GluR1, -2, -3, expressed in oocytes, nefiracetam or piracetam had no effect on the currents. Nefiracetam, thus, appears to facilitate hippocampal neurotransmission by functionally targeting nicotinic ACh receptors, independently of the action of piracetam and aniracetam.

Functional coupling of rat myometrial alpha 1-adrenergic receptors to Gh alpha/tissue transglutaminase 2 during pregnancy.

PubMed

Dupuis, Morgan; Lévy, Arlette; Mhaouty-Kodja, Sakina

2004-04-30

Gh alpha protein, which exhibits both transglutaminase and GTPase activities, represents a new class of GTP-binding proteins. In the present study, we characterized Gh alpha in rat uterine smooth muscle (myometrium) and followed its expression during pregnancy by reverse transcription-PCR and Western blot. We also measured transglutaminase and GTP binding functions and used a smooth muscle cell line to evaluate the role of Gh alpha in cell proliferation. The results show that pregnancy is associated with an up-regulation of Gh alpha expression at both the mRNA and protein level. Gh alpha induced during pregnancy is preferentially localized to the plasma membrane. This was found associated with an increased ability of plasma membrane preparations to catalyze Ca(2+)-dependent incorporation of [(3)H]putrescine into casein in vitro. In the cytosol, significant changes in the level of immunodetected Gh alpha and transglutaminase activity were seen only at term. Activation of alpha1-adrenergic receptors (alpha1-AR) enhanced photoaffinity labeling of plasma membrane Gh alpha. Moreover, the level of alpha1-AR-coupled Gh alpha increased progressively with pregnancy, which parallels the active period of myometrial cell proliferation. Overexpression of wild type Gh alpha in smooth muscle cell line DDT1-MF2 increased alpha1-AR-induced [(3)H]thymidine incorporation. A similar response was obtained in cells expressing the transglutaminase inactive mutant (C277S) of Gh alpha. Together, these findings underscore the role of Gh alpha as signal transducer of alpha1-AR-induced smooth muscle cell proliferation. In this context, pregnant rat myometrium provides an interesting physiological model to study the mechanisms underlying the regulation of the GTPase function of Gh alpha

Myocardial and vascular adrenergic alterations in a rat model of endotoxin shock: reversal by an anti-tumor necrosis factor-alpha monoclonal antibody.

PubMed

Boillot, A; Massol, J; Maupoil, V; Grelier, R; Bernard, B; Capellier, G; Berthelot, A; Barale, F

1997-03-01

a) To investigate responsiveness to exogenous catecholamines in rat endotoxin shock by studying both myocardial and vascular functional parameters, and to determine the relationship of these parameters with other relevant biological parameters of the adrenergic pathway, such as myocardial beta-adrenergic receptors and cyclic adenosine monophosphate (cAMP); b) to investigate the role of tumor necrosis factor (TNF)-alpha via prophylactic anti-TNF-alpha monoclonal antibody administration. Experimental, comparative hospital. Laboratory in a university hospital. Male Sprague-Dawley rats, weighing 280 to 340 g. Intravenous injection of Escherichia coli endotoxin (5 mg/100 g) in the first group; injection of the same dose of endotoxin preceded by 2 mg/100 g of anti-TNF-alpha monoclonal antibody in the second group; injection of saline in the third (control) group. TNF-alpha concentration was measured before and during the first 3 hrs in all three groups. Myocardial and vascular functional parameters were obtained, respectively, from Langendorff perfused hearts and isolated aortic rings. Adrenergic biochemical parameters (catecholamines, density and affinity of beta-receptors, and isoproterenol-stimulated myocardial cAMP) were determined 3 hrs after injections in the three groups. After endotoxin injection, serum TNF-alpha concentrations peaked at 60 mins (2496 +/- 412 pg/mL) and returned slowly to control values at 3 hrs; serum TNF-alpha concentrations remained under the limit of detection in the other two groups. When compared with the control group, plasma concentrations of epinephrine and norepinephrine were significantly (p < .05) increased. Baseline values for differential left ventricular pressure and coronary flow were significantly (p < .001, p < .01, respectively) reduced in the endotoxin group; heart rate remained unchanged. In the endotoxin and control groups, isoproterenol induced a similar increase in differential left ventricular pressure and in heart rate. Anti-TNF-alpha antibody increased cardiac response by partially preventing the decrease by endotoxin in differential left intraventricular pressure. Maximal specific binding of 125iodocyanopindolol and myocardial cAMP accumulation were significantly (p < .01) reduced in the endotoxin group in comparison with the control group. Anti-TNF-alpha antibody prevented the endotoxin-induced decrease in cAMP synthesis (p < .05) but did not modify the density of receptors. Affinity of receptors was similar in the three groups. In aortic rings, endotoxin administration significantly (p < .01) shifted the dose-response curve to norepinephrine to the right, both in the presence and absence of endothelium. NG-monomethyl-L-arginine significantly increased the contractions to attain the control level: p < .001 in the presence of endothelium; p < .05 in the absence of endothelium. Anti-TNF-alpha antibody did not prevent endotoxin-induced vascular hyporeactivity to norepinephrine in either endothelium-intact or -denuded rings, but partially attenuated the decrease in maximal response. In ex vivo experiments, 3 hrs after endotoxin injection, vascular responsiveness was sharply decreased. This impaired response was improved in vitro by the inhibition of nitric oxide. The heart response to isoproterenol, nevertheless, was maintained, even though there was an obvious decrease in receptor density and an impaired myocardial accumulation of cAMP. Anti-TNF-alpha antibody partially prevented the alteration of both myocardial pressure response to isoproterenol and biochemical parameters, and was not efficacious in preventing vascular hyporeactivity to vasoconstrictor agents.

Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP)-mediated Calcium Signaling and Arrhythmias in the Heart Evoked by β-Adrenergic Stimulation*♦

PubMed Central

Nebel, Merle; Schwoerer, Alexander P.; Warszta, Dominik; Siebrands, Cornelia C.; Limbrock, Ann-Christin; Swarbrick, Joanna M.; Fliegert, Ralf; Weber, Karin; Bruhn, Sören; Hohenegger, Martin; Geisler, Anne; Herich, Lena; Schlegel, Susan; Carrier, Lucie; Eschenhagen, Thomas; Potter, Barry V. L.; Ehmke, Heimo; Guse, Andreas H.

2013-01-01

Nicotinic acid adenine dinucleotide phosphate (NAADP) is the most potent Ca2+-releasing second messenger known to date. Here, we report a new role for NAADP in arrhythmogenic Ca2+ release in cardiac myocytes evoked by β-adrenergic stimulation. Infusion of NAADP into intact cardiac myocytes induced global Ca2+ signals sensitive to inhibitors of both acidic Ca2+ stores and ryanodine receptors and to NAADP antagonist BZ194. Furthermore, in electrically paced cardiac myocytes BZ194 blocked spontaneous diastolic Ca2+ transients caused by high concentrations of the β-adrenergic agonist isoproterenol. Ca2+ transients were recorded both as increases of the free cytosolic Ca2+ concentration and as decreases of the sarcoplasmic luminal Ca2+ concentration. Importantly, NAADP antagonist BZ194 largely ameliorated isoproterenol-induced arrhythmias in awake mice. We provide strong evidence that NAADP-mediated modulation of couplon activity plays a role for triggering spontaneous diastolic Ca2+ transients in isolated cardiac myocytes and arrhythmias in the intact animal. Thus, NAADP signaling appears an attractive novel target for antiarrhythmic therapy. PMID:23564460

Effects of ionotropic glutamate receptor antagonists on rat dural artery diameter in an intravital microscopy model.

PubMed

Chan, K Y; Gupta, S; de Vries, R; Danser, A H J; Villalón, C M; Muñoz-Islas, E; Maassenvandenbrink, A

2010-07-01

During migraine, trigeminal nerves may release calcitonin gene-related peptide (CGRP), inducing cranial vasodilatation and central nociception; hence, trigeminal inhibition or blockade of craniovascular CGRP receptors may prevent this vasodilatation and abort migraine headache. Several preclinical studies have shown that glutamate receptor antagonists affect the pathophysiology of migraine. This study investigated whether antagonists of NMDA (ketamine and MK801), AMPA (GYKI52466) and kainate (LY466195) glutamate receptors affected dural vasodilatation induced by alpha-CGRP, capsaicin and periarterial electrical stimulation in rats, using intravital microscopy. Male Sprague-Dawley rats were anaesthetized and the overlying bone was thinned to visualize the dural artery. Then, vasodilator responses to exogenous (i.v. alpha-CGRP) and endogenous (released by i.v. capsaicin and periarterial electrical stimulation) CGRP were elicited in the absence or presence of the above antagonists. alpha-CGRP, capsaicin and periarterial electrical stimulation increased dural artery diameter. Ketamine and MK801 inhibited the vasodilator responses to capsaicin and electrical stimulation, while only ketamine attenuated those to alpha-CGRP. In contrast, GYKI52466 only attenuated the vasodilatation to exogenous alpha-CGRP, while LY466195 did not affect the vasodilator responses to endogenous or exogenous CGRP. Although GYKI52466 has not been tested clinically, our data suggest that it would not inhibit migraine via vascular mechanisms. Similarly, the antimigraine efficacy of LY466195 seems unrelated to vascular CGRP-mediated pathways and/or receptors. In contrast, the cranial vascular effects of ketamine and MK801 may represent a therapeutic mechanism, although the same mechanism might contribute, peripherally, to cardiovascular side effects.

The 2.6 Angstrom Crystal Structure of a Human A[subscript 2A] Adenosine Receptor Bound to an Antagonist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaakola, Veli-Pekka; Griffith, Mark T.; Hanson, Michael A.

2009-01-15

The adenosine class of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) mediates the important role of extracellular adenosine in many physiological processes and is antagonized by caffeine. We have determined the crystal structure of the human A{sub 2A} adenosine receptor, in complex with a high-affinity subtype-selective antagonist, ZM241385, to 2.6 angstrom resolution. Four disulfide bridges in the extracellular domain, combined with a subtle repacking of the transmembrane helices relative to the adrenergic and rhodopsin receptor structures, define a pocket distinct from that of other structurally determined GPCRs. The arrangement allows for the binding of the antagonist in an extendedmore » conformation, perpendicular to the membrane plane. The binding site highlights an integral role for the extracellular loops, together with the helical core, in ligand recognition by this class of GPCRs and suggests a role for ZM241385 in restricting the movement of a tryptophan residue important in the activation mechanism of the class A receptors.« less

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

PubMed Central

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.

2017-01-01

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. PMID:28167537

Interaction between alpha 2-adrenergic and angiotensin II systems in the control of glomerular hemodynamics as assessed by renal micropuncture in the rat

NASA Technical Reports Server (NTRS)

Thomson, S. C.; Gabbai, F. B.; Tucker, B. J.; Blantz, R. C.

1992-01-01

The hypothesis that renal alpha 2 adrenoceptors influence nephron filtration rate (SNGFR) via interaction with angiotensin II (AII) was tested by renal micropuncture. The physical determinants of SNGFR were assessed in adult male Munich Wistar rats 5-7 d after ipsilateral surgical renal denervation (DNX). DNX was performed to isolate inhibitory central and presynaptic alpha 2 adrenoceptors from end-organ receptors within the kidney. Two experimental protocols were employed: one to test whether prior AII receptor blockade with saralasin would alter the glomerular hemodynamic response to alpha 2 adrenoceptor stimulation with the selective agonist B-HT 933 under euvolemic conditions, and the other to test whether B-HT 933 would alter the response to exogenous AII under conditions of plasma volume expansion. In euvolemic rats, B-HT 933 caused SNGFR to decline as the result of a decrease in glomerular ultrafiltration coefficient (LpA), an effect that was blocked by saralasin. After plasma volume expansion, B-HT 933 showed no primary effect on LpA but heightened the response of arterial blood pressure, glomerular transcapillary pressure gradient, and LpA to AII. The parallel results of these converse experiments suggest a complementary interaction between renal alpha 2-adrenergic and AII systems in the control of LpA.

Too much of a good thing: blocking noradrenergic facilitation in medial prefrontal cortex prevents the detrimental effects of chronic stress on cognition.

PubMed

Jett, Julianne D; Morilak, David A

2013-03-01

Cognitive impairments associated with dysfunction of the medial prefrontal cortex (mPFC) are prominent in stress-related psychiatric disorders. We have shown that enhancing noradrenergic tone acutely in the rat mPFC facilitated extra-dimensional (ED) set-shifting on the attentional set-shifting test (AST), whereas chronic unpredictable stress (CUS) impaired ED. In this study, we tested the hypothesis that the acute facilitatory effect of norepinephrine (NE) in mPFC becomes detrimental when activated repeatedly during CUS. Using microdialysis, we showed that the release of NE evoked in mPFC by acute stress was unchanged at the end of CUS treatment. Thus, to then determine if repeated elicitation of this NE activity in mPFC during CUS may have contributed to the ED deficit, we infused a cocktail of α(1)-, β(1)-, and β(2)-adrenergic receptor antagonists into the mPFC prior to each CUS session, then tested animals drug free on the AST. Antagonist treatment prevented the CUS-induced ED deficit, suggesting that NE signaling during CUS compromised mPFC function. We confirmed that this was not attributable to sensitization of adrenergic receptor function following chronic antagonist treatment, by administering an additional microinjection into the mPFC immediately prior to ED testing. Acute antagonist treatment did not reverse the beneficial effects of chronic drug treatment during CUS, nor have any effect on baseline ED performance in chronic vehicle controls. Thus, we conclude that blockade of noradrenergic receptors in mPFC protected against the detrimental cognitive effects of CUS, and that repeated elicitation of noradrenergic facilitatory activity is one mechanism by which chronic stress may promote mPFC cognitive dysfunction.

Pharmacologic Therapy in Men's Health: Hypogonadism, Erectile Dysfunction, and Benign Prostatic Hyperplasia.

PubMed

Berkseth, Kathryn E; Thirumalai, Arthi; Amory, John K

2016-07-01

This article reviews current pharmacologic treatment options for 3 common men's health concerns: hypogonadism, erectile dysfunction (ED), and benign prostatic hyperplasia (BPH). Specific topics addressed include: management of male hypogonadism using testosterone replacement therapy, use of oral phosphodiesterase inhibitors as first-line therapy for men with ED and the utility of intraurethral and intrapenile alprostadil injections for patients who do not respond to oral medications, and the role of alpha1-adrenergic antagonists, 5-alpha-reductase inhibitors, anticholinergic agents, and herbal therapies in the management of BPH. Copyright © 2016 Elsevier Inc. All rights reserved.

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

PubMed

Shirasaki, Hideaki; Kanaizumi, Etsuko; Himi, Tetsuo

2016-06-01

Adrenergic receptors (ARs) include four general types (α1, α2, β1 and β2), which are found in different target tissues. α-AR agonists are commonly used for decongestant therapy of upper airway diseases. In order to clarify the roles of AR subtypes in the upper airways, we investigated the localization of these receptors by immunohistochemistry. Human turbinates were obtained after turbinectomy from 12 patients with nasal obstruction refractory to medical therapy. The specific cells expressing α- and β-AR proteins were identified by immunostaining using an anti-human AR subtype-specific antibodies (α1A-, α1D-, α2C- and β2-ARs) antibody. Immunohistochemical analysis revealed that immunoreactivities for α1D- and β2-ARs were densely distributed in submucosal glands. In contrast, immunoreactivities for α1A- and 2C-ARs were densely distributed in vascular smooth muscle. Our results suggested that adrenergic receptor (AR) subtypes had different roles in upper airway diseases, such as allergic rhinitis and nonallergic rhinitis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Both alpha(1A)- and alpha(1B)-adrenergic receptors crosstalk to down regulate beta(1)-ARs in mouse heart: coupling to differential PTX-sensitive pathways.

PubMed

Rorabaugh, Boyd R; Gaivin, Robert J; Papay, Robert S; Shi, Ting; Simpson, Paul C; Perez, Dianne M

2005-11-01

Adrenergic receptors (ARs) play an important role in the regulation of cardiac function. Cardiac inotropy is primarily regulated by beta(1)-ARs. However, alpha(1)-ARs may play an important role in inotropy during heart failure. Previous work has suggested that the alpha(1B)-AR modulates beta(1)-AR function in the heart. The potential role of the alpha(1A)-AR has not been previously studied. We used transgenic mice that express constitutively active mutant (CAM) forms of the alpha(1A)-AR or alpha(1B)-AR regulated by their endogenous promoters. Expression of the CAM alpha(1A)-AR or CAM alpha(1B)-AR had no effect on basal cardiac function (developed pressure, +dP/dT, -dP/dT, heart rate, flow rate). However, both alpha(1)-AR subtypes significantly decreased isoproterenol-stimulated +dP/dT. Pertussis toxin had no effect on +dP/dT in CAM alpha(1A)-AR hearts but restored +dP/dT to non-transgenic values in CAM alpha(1B)-AR hearts. Radioligand binding indicated a selective decrease in the density of beta(1)-ARs in both CAM mice. However, G-proteins, cAMP, or the percentage of high and low affinity states were unchanged in either transgenic compared with control. These data demonstrate that CAM alpha(1A)- and alpha(1B)-ARs both down regulate beta(1)-AR-mediated inotropy in the mouse heart. However, alpha(1)-AR subtypes are coupled to different beta-AR mediated signaling pathways with the alpha(1B)-AR being pertussis toxin sensitive.

Treatment of Post-Traumatic Stress Disorders with the Alpha-1 Adrenergic Antagonist Prazosin.

PubMed

Simon, Philippe Yves Rémy; Rousseau, Pierre-François

2017-03-01

The present review aims to assess the clinical efficacy and safety of the α-1-adrenergic antagonist prazosin as primary pharmacologic treatment for post-traumatic stress disorder (PTSD). A systematic review was performed using keywords (i.e., prazosin, α-1-adrenergic antagonist, α-1-blocker, post-traumatic stress disorder) in the databases PubMed/Medline (1966-May 2016), Embase (1966-May 2016), ScienceDirect (1823-May 2016), OvidSP (1946-May 2016) and Nature (1845-May 2016). To be considered for inclusion, studies had to test the efficacy of prazosin either alone or added to ongoing treatment in adults with PTSD, use validated tools to assess and monitor the disorders, allow comparisons on the basis of univariate analyses (i.e., p-values of t-tests and effect sizes) and list the identified adverse reactions. 12 studies were included: 5 randomized controlled trials, 4 open-label prospective trials and 3 retrospective file reviews. The evaluation concerned 276 patients exposed to civilian trauma (19%) or war trauma (81%). Prazosin significantly decreases trauma nightmares, avoidance, hypervigilance and improves patient status in all studies. No significant difference of blood pressure was observed at the end of trials. Beyond the methodological and clinical biases of these studies, the present review not only confirms the effectiveness and good tolerability of prazosin, but also suggests its possible use as primary pharmacologic treatment for PTSD. Uncertainties remain, however, regarding the prescription modalities and dosages.

Neomycin is a platelet-derived growth factor (PDGF) antagonist that allows discrimination of PDGF alpha- and beta-receptor signals in cells expressing both receptor types.

PubMed

Vassbotn, F S; Ostman, A; Siegbahn, A; Holmsen, H; Heldin, C H

1992-08-05

The aminoglycoside neomycin has recently been found to affect certain platelet-derived growth factor (PDGF) responses in C3H/10T1/2 C18 fibroblasts. Using porcine aortic endothelial cells transfected with PDGF alpha- or beta-receptors, we explored the possibility that neomycin interferes with the interaction between the different PDGF isoforms and their receptors. We found that neomycin (5 mM) inhibited the binding of 125I-PDGF-BB to the alpha-receptor with only partial effect on the binding of 125I-PDGF-AA; in contrast, the binding of 125I-PDGF-BB to the beta-receptor was not affected by the aminoglycoside. Scatchard analyses showed that neomycin (5 mM) decreased the number of binding sites for PDGF-BB on alpha-receptor-expressing cells by 87%. Together with cross-competition studies with 125I-labeled PDGF homodimers, the effect of neomycin indicates that PDGF-AA and PDGF-BB bind to both common and unique structures on the PDGF alpha-receptor. Neomycin specifically inhibited the autophosphorylation of the alpha-receptor by PDGF-BB, with less effect on the phosphorylation induced by PDGF-AA and no effect on the phosphorylation of the beta-receptor by PDGF-BB. Thus, neomycin is a PDGF isoform- and receptor-specific antagonist that provides a possibility to compare the signal transduction pathways of alpha- and beta-receptors in cells expressing both receptor types. This approach was used to show that activation of PDGF beta-receptors by PDGF-BB mediated a chemotactic response in human fibroblasts, whereas activation of alpha-receptors by the same ligand inhibited chemotaxis.

Disruption of Long-Term Alcohol-Related Memory Reconsolidation: Role of β-Adrenoceptors and NMDA Receptors

PubMed Central

Wouda, Jelte A.; Diergaarde, Leontien; Riga, Danai; van Mourik, Yvar; Schoffelmeer, Anton N. M.; De Vries, Taco J.

2010-01-01

Disrupting reconsolidation of drug-related memories may be effective in reducing the incidence of relapse. In the current study we examine whether alcohol-related memories are prone to disruption by the β-adrenergic receptor antagonist propranolol (10 mg/kg) and the NMDA receptor antagonist MK801 (0.1 mg/kg) following their reactivation. In operant chambers, male Wistar rats were trained to self-administer a 12% alcohol solution. After 3 weeks of abstinence, the animals were placed in the self-administration cages and were re-exposed to the alcohol-associated cues for a 20-min retrieval period, immediately followed by a systemic injection of either propranolol, MK801 or saline. Rats were tested for cue-induced alcohol seeking on the following day. Retrieval session, injection and test were repeated on two further occasions at weekly intervals. Both propranolol and MK801 administration upon reactivation did not reduce alcohol seeking after the first reactivation test. However, a significant reduction of alcohol seeking was observed over three post-training tests in propranolol treated animals, and MK801 treated animals showed a strong tendency toward reduced alcohol seeking (p = 0.06). Our data indicate that reconsolidation of alcohol-related memories can be disrupted after a long post-training interval and that particularly β-adrenergic receptors may represent novel targets for pharmacotherapy of alcoholism, in combination with cue-exposure therapies. PMID:21152256

An immunocapture/scintillation proximity analysis of G alpha q/11 activation by native serotonin (5-HT)2A receptors in rat cortex: blockade by clozapine and mirtazapine.

PubMed

Mannoury La Cour, C; Chaput, C; Touzard, M; Millan, M J

2009-02-01

Though transduction mechanisms recruited by heterologously expressed 5-HT(2A) receptors have been extensively studied, their interaction with specific subtypes of G-protein remains to be directly evaluated in cerebral tissue. Herein, as shown by an immunocapture/scintillation proximity analysis, 5-HT, the prototypical 5-HT(2A) agonist, DOI, and Ro60,0175 all enhanced [(35)S]GTPgammaS binding to G alpha q/11 in rat cortex with pEC(50) values of 6.22, 7.24 and 6.35, respectively. No activation of G o or G s/olf was seen at equivalent concentrations of DOI. Stimulation of G alpha q/11 by 5-HT (30 microM) and DOI (30 microM) was abolished by the selective 5-HT(2A) vs. 5-HT(2C)/5-HT(2B) antagonists, ketanserin (pK(B) values of 9.11 and 8.88, respectively) and MDL100,907 (9.82 and 9.68). By contrast, 5-HT-induced [(35)S]GTPgammaS binding to G alpha q/11 was only weakly inhibited by the preferential 5-HT(2C) receptor antagonists, RS102,221 (6.94) and SB242,084 (7.39), and the preferential 5-HT(2B) receptor antagonist, LY266,097 (6.66). The antipsychotic, clozapine, which had marked affinity for 5-HT(2A) receptors, blocked the recruitment of G alpha q/11 by 5-HT and DOI with pK(B) values of 8.54 and 8.14, respectively. Its actions were mimicked by the "atypical" antidepressant and 5-HT(2A) receptor antagonist, mirtazapine, which likewise blocked 5-HT and DOI-induced G alpha q/11 protein activation with pK(B) values of 7.90 and 7.76, respectively. In conclusion, by use of an immunocapture/scintillation proximity strategy, this study shows that native 5-HT(2A) receptors in rat frontal cortex specifically recruit G alpha q/11 and that this action is blocked by clozapine and mirtazapine. Quantification of 5-HT(2A) receptor-mediated G alpha q/11 activation in frontal cortex should prove instructive in characterizing the actions of diverse classes of psychotropic agent. 2008 Wiley-Liss, Inc.

Olfactory Perceptual Learning Requires Action of Noradrenaline in the Olfactory Bulb: Comparison with Olfactory Associative Learning

ERIC Educational Resources Information Center

Vinera, Jennifer; Kermen, Florence; Sacquet, Joëlle; Didier, Anne; Mandairon, Nathalie; Richard, Marion

2015-01-01

Noradrenaline contributes to olfactory-guided behaviors but its role in olfactory learning during adulthood is poorly documented. We investigated its implication in olfactory associative and perceptual learning using local infusion of mixed a1-ß adrenergic receptor antagonist (labetalol) in the adult mouse olfactory bulb. We reported that…

Antinociceptive effects of the aqueous and methanol extracts of the leaves of Pittosporum mannii Hook. F. (Pittosporaceae) in mice.

PubMed

Wandji, Bibiane Aimée; Tatsinkou Bomba, Francis Desire; Awouafack, Maurice Ducret; Nkeng-Efouet, Pepin Alango; Kamanyi, Albert; Nguelefack, Télesphore Benoît

2016-07-01

Pittosporum mannii (Pittosporaceae) is used in Africa traditional medicine to treat various ailments including pain and inflammation. The present work was undertaken to evaluate the antinociceptive effects of the aqueous (AEPM) and methanol (MEPM) extracts from the leaves of Pittosporum mannii. High performance liquid chromatography coupled with mass spectrometry (LCMS) was used for the phytochemical analysis of AEPM prepared as decoction and MEPM prepared as cold maceration. The in vitro cytotoxicity of AEPM and MEPM were evaluated on Artemia salina larvae. AEPM and MEPM antinociceptive effects were evaluated at the doses of 35, 75, 150 and 300mg/kg given orally, against pain induced by acetic acid, formalin, hot plate, capsaicin and glutamate. The rota rod test was also performed at the same doses. To determine the mechanism of action of these extracts, their antinociceptive effects were tested in animals pretreated with yohimbine (α2-adrenergic antagonist), atropine (muscarinic antagonist) or naloxone (an opioids antagonist). The LCMS analysis showed that both extracts contain pittovidoside and 1-O-rhamnopyranosyl-23-acetoxyimberbic acid 29-methyl ester, the aqueous extract being more concentrated. Oral administration of both extracts significantly reduced pain symptoms induced by acetic acid, formalin, capsaicin, glutamate and hot plate. The antinociceptive effect of AEPM was significantly inhibited by yohimbine, atropine and naloxone while these inhibitors tend to potentiate the activity of MEPM. Both extracts have no effect on Rota rod test. AEPM and MEPM showed respective LC50 of 2.44 and 0.70mg/ml on Artemia larvae and were therefore, considered non-toxic. These results indicate that AEPM and MEPM possesses analgesic effects with different mechanism of action. Although effects of both extracts may involve TRPV1 receptors and glutamatergic pathway, AEPM may in addition, interact with alpha-adrenergic, muscarinic and opioidergic pathways that are not involve in the effects of MEPM. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Pharmacological lineage analysis revealed the binding affinity of broad-spectrum substance P antagonists to receptors for gonadotropin-releasing peptide.

PubMed

Arai, Kazune; Kashiwazaki, Aki; Fujiwara, Yoko; Tsuchiya, Hiroyoshi; Sakai, Nobuya; Shibata, Katsushi; Koshimizu, Taka-aki

2015-02-15

A group of synthetic substance P (SP) antagonists, such as [Arg(6),D-Trp(7,9),N(Me)Phe(8)]-substance P(6-11) and [D-Arg(1),D-Phe(5),D-Trp(7,9),Leu(11)]-substance P, bind to a range of distinct G-protein-coupled receptor (GPCR) family members, including V1a vasopressin receptors, and they competitively inhibit agonist binding. This extended accessibility enabled us to identify a GPCR subset with a partially conserved binding site structure. By combining pharmacological data and amino acid sequence homology matrices, a pharmacological lineage of GPCRs that are sensitive to these two SP antagonists was constructed. We found that sensitivity to the SP antagonists was not limited to the Gq-protein-coupled V1a and V1b receptors; Gs-coupled V2 receptors and oxytocin receptors, which couple with both Gq and Gi, also demonstrated sensitivity. Unexpectedly, a dendrogram based on the amino acid sequences of 222 known GPCRs showed that a group of receptors sensitive to the SP antagonists are located in close proximity to vasopressin/oxytocin receptors. Gonadotropin-releasing peptide receptors, located near the vasopressin receptors in the dendrogram, were also sensitive to the SP analogs, whereas α1B adrenergic receptors, located more distantly from the vasopressin receptors, were not sensitive. Our finding suggests that pharmacological lineage analysis is useful in selecting subsets of candidate receptors that contain a conserved binding site for a ligand with broad-spectrum binding abilities. The knowledge that the binding site of the two broad-spectrum SP analogs partially overlaps with that of distinct peptide agonists is valuable for understanding the specificity/broadness of peptide ligands. Copyright © 2015 Elsevier B.V. All rights reserved.

Blockade of α2-adrenergic receptors in prelimbic cortex: impact on cocaine self-administration in adult spontaneously hypertensive rats following adolescent atomoxetine treatment.

PubMed

Baskin, Britahny M; Nic Dhonnchadha, Bríd Á; Dwoskin, Linda P; Kantak, Kathleen M

2017-10-01

Research with the spontaneously hypertensive rat (SHR) model of attention deficit/hyperactivity disorder demonstrated that chronic methylphenidate treatment during adolescence increased cocaine self-administration established during adulthood under a progressive ratio (PR) schedule. Compared to vehicle, chronic atomoxetine treatment during adolescence failed to increase cocaine self-administration under a PR schedule in adult SHR. We determined if enhanced noradrenergic transmission at α2-adrenergic receptors within prefrontal cortex contributes to this neutral effect of adolescent atomoxetine treatment in adult SHR. Following treatment from postnatal days 28-55 with atomoxetine (0.3 mg/kg) or vehicle, adult male SHR and control rats from Wistar-Kyoto (WKY) and Wistar (WIS) strains were trained to self-administer 0.3 mg/kg cocaine. Self-administration performance was evaluated under a PR schedule of cocaine delivery following infusion of the α2-adrenergic receptor antagonist idazoxan (0 and 10-56 μg/side) directly into prelimbic cortex. Adult SHR attained higher PR break points and had greater numbers of active lever responses and infusions than WKY and WIS. Idazoxan dose-dependently increased PR break points and active lever responses in SHR following adolescent atomoxetine vs. vehicle treatment. Behavioral changes were negligible after idazoxan pretreatment in SHR following adolescent vehicle or in WKY and WIS following adolescent atomoxetine or vehicle. α2-Adrenergic receptor blockade in prelimbic cortex of SHR masked the expected neutral effect of adolescent atomoxetine on adult cocaine self-administration behavior. Moreover, greater efficacy of acute idazoxan challenge in adult SHR after adolescent atomoxetine relative to vehicle is consistent with the idea that chronic atomoxetine may downregulate presynaptic α2A-adrenergic autoreceptors in SHR.

Anxiolytic-like and antidepressant-like activities of MCL0129 (1-[(S)-2-(4-fluorophenyl)-2-(4-isopropylpiperadin-1-yl)ethyl]-4-[4-(2-methoxynaphthalen-1-yl)butyl]piperazine), a novel and potent nonpeptide antagonist of the melanocortin-4 receptor.

PubMed

Chaki, Shigeyuki; Hirota, Shiho; Funakoshi, Takeo; Suzuki, Yoshiko; Suetake, Sayoko; Okubo, Taketoshi; Ishii, Takaaki; Nakazato, Atsuro; Okuyama, Shigeru

2003-02-01

We investigated the effects of a novel melanocortin-4 (MC4) receptor antagonist,1-[(S)-2-(4-fluorophenyl)-2-(4-isopropylpiperadin-1-yl)ethyl]-4-[4-(2-methoxynaphthalen-1-yl)butyl]piperazine (MCL0129) on anxiety and depression in various rodent models. MCL0129 inhibited [(125)I][Nle(4)-D-Phe(7)]-alpha-melanocyte-stimulating hormone (alpha-MSH) binding to MC4 receptor with a K(i) value of 7.9 nM, without showing affinity for MC1 and MC3 receptors. MCL0129 at 1 microM had no apparent affinity for other receptors, transporters, and ion channels related to anxiety and depression except for a moderate affinity for the sigma(1) receptor, serotonin transporter, and alpha(1)-adrenoceptor, which means that MCL0129 is selective for the MC4 receptor. MCL0129 attenuated the alpha-MSH-increased cAMP formation in COS-1 cells expressing the MC4 receptor, whereas MCL0129 did not affect basal cAMP levels, thereby indicating that MCL0129 acts as an antagonist at the MC4 receptor. Swim stress markedly induced anxiogenic-like effects in both the light/dark exploration task in mice and the elevated plus-maze task in rats, and MCL0129 reversed the stress-induced anxiogenic-like effects. Under nonstress conditions, MCL0129 prolonged time spent in the light area in the light/dark exploration task and suppressed marble-burying behavior. MCL0129 shortened immobility time in the forced swim test and reduced the number of escape failures in inescapable shocks in the learned helplessness test, thus indicating an antidepressant potential. In contrast, MCL0129 had negligible effects on spontaneous locomotor activity, Rotarod performance, and hexobarbital-induced anesthesia. These observations indicate that MCL0129 is a potent and selective MC4 antagonist with anxiolytic- and antidepressant-like activities in various rodent models. MC4 receptor antagonists may prove effective for treating subjects with stress-related disorders such as depression and/or anxiety.

Inhibition of agonist-induced smooth muscle contraction by picotamide in the male human lower urinary tract outflow region.

PubMed

Hennenberg, Martin; Tamalunas, Alexander; Wang, Yiming; Keller, Patrick; Schott, Melanie; Strittmatter, Frank; Herlemann, Annika; Yu, Qingfeng; Rutz, Beata; Ciotkowska, Anna; Stief, Christian G; Gratzke, Christian

2017-05-15

Male lower urinary tract symptoms (LUTS) due to bladder outlet obstruction are characterized by abnormal smooth muscle contractions in the lower urinary tract. Alpha 1 -adrenoceptor antagonists may induce smooth muscle relaxation in the outflow region and represent the current gold standard of medical treatment. However, results may be unsatisfactory or inadequate. Apart from α 1 -adrenoceptor agonists, smooth muscle contraction in the outflow region may be induced by thromboxane A 2 (TXA 2 ), endothelins, or muscarinic receptor agonists. Here, we studied effects of the thromboxane A 2 receptor (TP receptor) antagonist picotamide on contraction in the human male bladder trigone and prostate. Carbachol, the α 1 -adrenoceptor agonist phenylephrine, the thromboxane A 2 analog U46619, and electric field stimulation (EFS) induced concentration- or frequency-dependent contractions of trigone tissues in an organ bath. Picotamide (300µM) inhibited carbachol-, phenylephrine-, U46619-, and EFS-induced contractions. Endothelins 1-3 induced concentration-dependent contractions of prostate tissues, which were inhibited by picotamide. Analyses using real time polymerase chain reaction and antibodies suggested expression of thromboxane A 2 receptors and synthase in trigone smooth muscle cells. Thromboxane B 2 (the stable metabolite of thromboxane A 2 ) was detectable by enzyme immune assay in trigone samples, with most values ranging between 50 and 150pg/mg trigone protein. Picotamide inhibits contractions induced by different stimuli in the human lower urinary tract, including cholinergic, adrenergic, thromboxane A 2 - and endothelin-induced, and neurogenic contractions in different locations of the outflow region. This distinguishes picotamide from current medical treatments for LUTS, and suggests that picotamide may induce urodynamic effects in vivo. Copyright © 2017. Published by Elsevier B.V.

β-Adrenergic receptor antagonism prevents anxiety-like behavior and microglial reactivity induced by repeated social defeat.

PubMed

Wohleb, Eric S; Hanke, Mark L; Corona, Angela W; Powell, Nicole D; Stiner, La'Tonia M; Bailey, Michael T; Nelson, Randy J; Godbout, Jonathan P; Sheridan, John F

2011-04-27

Psychosocial stress is associated with altered immune function and development of psychological disorders including anxiety and depression. Here we show that repeated social defeat in mice increased c-Fos staining in brain regions associated with fear and threat appraisal and promoted anxiety-like behavior in a β-adrenergic receptor-dependent manner. Repeated social defeat also significantly increased the number of CD11b(+)/CD45(high)/Ly6C(high) macrophages that trafficked to the brain. In addition, several inflammatory markers were increased on the surface of microglia (CD14, CD86, and TLR4) and macrophages (CD14 and CD86) after social defeat. Repeated social defeat also increased the presence of deramified microglia in the medial amygdala, prefrontal cortex, and hippocampus. Moreover, mRNA analysis of microglia indicated that repeated social defeat increased levels of interleukin (IL)-1β and reduced levels of glucocorticoid responsive genes [glucocorticoid-induced leucine zipper (GILZ) and FK506 binding protein-51 (FKBP51)]. The stress-dependent changes in microglia and macrophages were prevented by propranolol, a β-adrenergic receptor antagonist. Microglia isolated from socially defeated mice and cultured ex vivo produced markedly higher levels of IL-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 after stimulation with lipopolysaccharide compared with microglia from control mice. Last, repeated social defeat increased c-Fos activation in IL-1 receptor type-1-deficient mice, but did not promote anxiety-like behavior or microglia activation in the absence of functional IL-1 receptor type-1. These findings indicate that repeated social defeat-induced anxiety-like behavior and enhanced reactivity of microglia was dependent on activation of β-adrenergic and IL-1 receptors.

β-Adrenergic Receptor Antagonism Prevents Anxiety-like Behavior and Microglial Reactivity Induced by Repeated Social Defeat

PubMed Central

Wohleb, Eric S.; Hanke, Mark L.; Corona, Angela W.; Powell, Nicole D.; Stiner, La'Tonia M.; Bailey, Michael T.; Nelson, Randy J.; Godbout, Jonathan P.; Sheridan, John F.

2011-01-01

Psychosocial stress is associated with altered immune function and development of psychological disorders including anxiety and depression. Here we show that repeated social defeat in mice increased c-Fos staining in brain regions associated with fear and threat appraisal and promoted anxiety-like behavior in a β-adrenergic receptor-dependent manner. Repeated social defeat also significantly increased the number of CD11b+/CD45high/Ly6Chigh macrophages that trafficked to the brain. In addition, several inflammatory markers were increased on the surface of microglia (CD14, CD86, and TLR4) and macrophages (CD14 and CD86) after social defeat. Repeated social defeat also increased the presence of de-ramified microglia in the medial amygdala, prefrontal cortex, and hippocampus. Moreover, mRNA analysis of microglia indicated that repeated social defeat increased levels of interleukin (IL)-1β and reduced levels of glucocorticoid responsive genes (GILZ and FKBP51). The stress-dependent changes in microglia and macrophages were prevented by propranolol, a β-adrenergic receptor antagonist. Microglia isolated from socially defeated mice and cultured ex vivo produced markedly higher levels of IL-6, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein-1 (MCP-1) after stimulation with lipopolysaccharide (LPS) compared to microglia from control mice. Last, repeated social defeat increased c-Fos activation in IL-1 receptor type-1 deficient (IL-1r1-/-) mice, but did not promote anxiety-like behavior or microglia activation in the absence of functional IL-1 receptor type-1. These findings indicate that repeated social defeat-induced anxiety-like behavior and enhanced reactivity of microglia was dependent on activation of β-adrenergic and IL-1 receptors. PMID:21525267

Selective ablation of dorsal horn NK1 expressing cells reveals a modulation of spinal alpha2-adrenergic inhibition of dorsal horn neurones.

PubMed

Rahman, Wahida; Suzuki, Rie; Hunt, Stephen P; Dickenson, Anthony H

2008-06-01

Activity in descending systems from the brainstem modulates nociceptive transmission through the dorsal horn. Intrathecal injection of the neurotoxin saporin conjugated to SP (SP-SAP) into the lumbar spinal cord results in the selective ablation of NK(1) receptor expressing (NK(1)+ve) neurones in the superficial dorsal horn (lamina I/III). Loss of these NK(1)+ve neurones attenuates excitability of deep dorsal horn neurones due to a disruption of both intrinsic spinal circuits and a spino-bulbo-spinal loop, which activates a descending excitatory drive, mediated through spinal 5HT(3) receptors. Descending inhibitory pathways also modulate spinal activity and hence control the level of nociceptive transmission relayed to higher centres. To ascertain the spinal origins of the major descending noradrenergic inhibitory pathway we studied the effects of a selective alpha2-adrenoceptor antagonist, atipamezole, on neuronal activity in animals pre-treated with SP-SAP. Intrathecal application of atipamezole dose dependently facilitated the mechanically evoked neuronal responses of deep dorsal horn neurones to low intensity von Frey hairs (5-15 g) and noxious thermal (45-50 degrees C) evoked responses in SAP control animals indicating a physiological alpha2-adrenoceptor control. This facilitatory effect of atipamezole was lost in the SP-SAP treated group. These data suggest that activity within noradrenergic pathways have a dependence on dorsal horn NK(1)+ve cells. Further, noradrenergic descending inhibition may in part be driven by lamina I/III (NK(1)+ve) cells, and mediated via spinal alpha2-adrenoceptor activation. Since the same neuronal population drives descending facilitation and inhibition, the reduced excitability of lamina V/VI WDR neurones seen after loss of these NK(1)+ve neurones indicates a dominant role of descending facilitation.

Characterization of alpha(4)beta(1) (CD49d/CD29) on equine leukocytes: potential utility of a potent alpha(4)beta(1) (CD49d/CD29) receptor antagonist in the treatment of equine heaves (recurrent airway obstruction).

PubMed

Treonze, Kelly M; Alves, Kenneth; Fischer, Paul; Hagmann, William K; Hora, Donald; Kulick, Alison; Vakerich, Ken; Smith, Nicholas D; Lingham, Russell B; Maniar, Salony; Reger, Thomas S; Zunic, Jasmine; Munoz, Benito; Prasit, Peppi; Nicholson, Donald; Si, Qian; Judd, Keith; Nicolich, Susan; Kellerhouse, Patricia; Thompson, Donald; Mumford, Richard A

2009-07-15

The purpose of this study was to characterize the alpha(4)beta(1) receptor (CD49d/CD29, very late antigen-4, VLA-4) on circulating equine leukocytes and to evaluate the intrinsic potency of an alpha(4)beta(1) receptor antagonist (Compound B) in the horse. Ultimately, these studies would allow us to determine the suitability of treating recurrent airway obstruction (RAO; heaves) affected horses by blocking the cellular recruitment of lymphocytes and neutrophils into the lung. The data demonstrates the alpha(4)beta(1) integrin is present on horse lymphocytes and neutrophils (fluorescence-assisted cell sorter, FACS) and can bind low molecular weight alpha(4)beta(1) antagonists (Compounds A and B) with high affinity. K(D) values for the binding of Compound A to non-activated alpha(4)beta(1) on isolated horse PBMCs (peripheral blood mononuclear cells) and activated neutrophils were 17 pM and 27 pM, respectively. Compound B was identified as a suitable antagonist for performing a series of in vivo experiments. Compound B was found to possess excellent potency in horse whole blood, possessing IC(50) and IC(90) values of 39 pM and 172 pM, respectively. This represents a 3.9-fold molar excess of drug over the alpha(4)beta(1) concentration in blood. Following oral administration of Compound B (5 mg/kg) to beagle dogs and rhesus monkeys, rapid and sustained alpha(4)beta(1) receptor occupancy (>80%) was achieved and maintained for a period of 24 h. When Compound B was administered intravenously to the horse, by either a slow or rapid infusion at a dose of 0.3 mg/kg, receptor blockade of >80% was observed out to 24 h with a concomitant leukocytosis. We believe that Compound B possesses suitable intrinsic and pharmacological properties to be evaluated clinically in horses affected by RAO.

Norepinephrine and dopamine increase motility, biofilm formation, and virulence of Vibrio harveyi

PubMed Central

Yang, Qian; Anh, Nguyen D. Q.; Bossier, Peter; Defoirdt, Tom

2014-01-01

Vibrio harveyi is one of the major pathogens of aquatic organisms, affecting both vertebrates and invertebrates, and causes important losses in the aquaculture industry. In order to develop novel methods to control disease caused by this pathogen, we need to obtain a better understanding of pathogenicity mechanisms. Sensing of catecholamines increases both growth and production of virulence-related factors in pathogens of terrestrial animals and humans. However, at this moment, knowledge on the impact of catecholamines on the virulence of pathogens of aquatic organisms is lacking. In the present study, we report that in V. harveyi, norepinephrine (NE) and dopamine (Dopa) increased growth in serum-supplemented medium, siderophore production, swimming motility, and expression of genes involved in flagellar motility, biofilm formation, and exopolysaccharide production. Consistent with this, pretreatment of V. harveyi with catecholamines prior to inoculation into the rearing water resulted in significantly decreased survival of gnotobiotic brine shrimp larvae, when compared to larvae challenged with untreated V. harveyi. Further, NE-induced effects could be neutralized by α-adrenergic antagonists or by the bacterial catecholamine receptor antagonist LED209, but not by β-adrenergic or dopaminergic antagonists. Dopa-induced effects could be neutralized by dopaminergic antagonists or LED209, but not by adrenergic antagonists. Together, our results indicate that catecholamine sensing increases the success of transmission of V. harveyi and that interfering with catecholamine sensing might be an interesting strategy to control vibriosis in aquaculture. We hypothesize that upon tissue and/or hemocyte damage during infection, pathogens come into contact with elevated catecholamine levels, and that this stimulates the expression of virulence factors that are required to colonize a new host. PMID:25414697

Solution structure of {alpha}-conotoxin PIA, a novel antagonist of {alpha}6 subunit containing nicotinic acetylcholine receptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Seung-Wook; Lee, Si-Hyung; Kim, Do-Hyoung

2005-12-30

{alpha}-Conotoxin PIA is a novel nicotinic acetylcholine receptor (nAChR) antagonist isolated from Conus purpurascens that targets nAChR subtypes containing {alpha}6 and {alpha}3 subunits. {alpha}-conotoxin PIA displays 75-fold higher affinity for rat {alpha}6/{alpha}3{beta}2{beta}3 nAChRs than for rat {alpha}3{beta}2 nAChRs. We have determined the three-dimensional structure of {alpha}-conotoxin PIA by nuclear magnetic resonance spectroscopy. The {alpha}-conotoxin PIA has an '{omega}-shaped' overall topology as other {alpha}4/7 subfamily conotoxins. Yet, unlike other neuronally targeted {alpha}4/7-conotoxins, its N-terminal tail Arg{sup 1}-Asp{sup 2}-Pro{sup 3} protrudes out of its main molecular body because Asp{sup 2}-Pro{sup 3}-Cys{sup 4}-Cys{sup 5} forms a stable type I {beta}-turn. In addition, amore » kink introduced by Pro{sup 15} in the second loop of this toxin provides a distinct steric and electrostatic environment from those in {alpha}-conotoxins MII and GIC. By comparing the structure of {alpha}-conotoxin PIA with other functionally related {alpha}-conotoxins we suggest structural features in {alpha}-conotoxin PIA that may be associated with its unique receptor recognition profile.« less

β-Adrenergic Regulation of Cardiac Progenitor Cell Death Versus Survival and Proliferation

PubMed Central

Khan, Mohsin; Mohsin, Sadia; Avitabile, Daniele; Siddiqi, Sailay; Nguyen, Jonathan; Wallach, Kathleen; Quijada, Pearl; McGregor, Michael; Gude, Natalie; Alvarez, Roberto; Tilley, Douglas G.; Koch, Walter J.; Sussman, Mark A.

2013-01-01

Rationale Short-term β-adrenergic stimulation promotes contractility in response to stress but is ultimately detrimental in the failing heart because of accrual of cardiomyocyte death. Endogenous cardiac progenitor cell (CPC) activation may partially offset cardiomyocyte losses, but consequences of long-term β-adrenergic drive on CPC survival and proliferation are unknown. Objective We sought to determine the relationship between β-adrenergic activity and regulation of CPC function. Methods and Results Mouse and human CPCs express only β2 adrenergic receptor (β2-AR) in conjunction with stem cell marker c-kit. Activation of β2-AR signaling promotes proliferation associated with increased AKT, extracellular signal-regulated kinase 1/2, and endothelial NO synthase phosphorylation, upregulation of cyclin D1, and decreased levels of G protein–coupled receptor kinase 2. Conversely, silencing of β2-AR expression or treatment with β2-antagonist ICI 118, 551 impairs CPC proliferation and survival. β1-AR expression in CPC is induced by differentiation stimuli, sensitizing CPC to isoproterenol-induced cell death that is abrogated by metoprolol. Efficacy of β1-AR blockade by metoprolol to increase CPC survival and proliferation was confirmed in vivo by adoptive transfer of CPC into failing mouse myocardium. Conclusions β-adrenergic stimulation promotes expansion and survival of CPCs through β2-AR, but acquisition of β1-AR on commitment to the myocyte lineage results in loss of CPCs and early myocyte precursors. PMID:23243208

Duration and mechanisms of the increased natural cytotoxicity seen after chronic voluntary exercise in rats.

PubMed

Jonsdottir, I H; Johansson, C; Asea, A; Johansson, P; Hellstrand, K; Thorén, P; Hoffmann, P

1997-08-01

We have recently shown that in vivo natural cytotoxicity is enhanced after chronic exercise in spontaneously hypertensive rats (SHRs). In the present report, we have studied the duration of this augmentation and some possible mechanisms involved. Exercise consisted of voluntary running for 4-5 weeks, with the running distance ranging from 2.7-15.6 km day(-1) during the last week of running. In vivo cytotoxicity was measured as clearance of injected 51Cr-labelled YAC-1 lymphoma cells from the lungs. The in vivo natural cytotoxicity was increased in running SHRs, and also in SHRs that had their running wheel locked for 24 and 48 h prior to the experiment, and was still present after 96 h. The enhancement of in vivo cytotoxicity after 5 weeks of exercise was abolished after an acute injection of the beta-adrenergic receptor antagonist timolol (0.5 mg kg(-1) i.v.), indicating that catecholamines are involved in this augmentation. Interestingly, 24 h after the last exercise bout, the increased natural cytotoxicity could be blocked by timolol. The opioid receptor antagonist naloxone given subcutaneously for 7 days by osmotic pumps (6 mg kg(-1) h(-1)) could not reverse the increased in vivo cytotoxicity seen in the running SHRs, suggesting that opioid receptor mechanisms are not involved, or at least not the naloxone-sensitive mu-receptor. Natural immunity was not influenced by the histamine H2 receptor antagonist ranitidine, either in controls or in runners, indicating that the natural killer cell-regulatory effect of histamine is not present in SHRs and does not seem to be involved in the exercise-induced changes in natural immune function. We conclude that the augmentation of in vivo natural cytotoxicity after voluntary chronic exercise in rats is long-lasting and that the augmentation is partly mediated by beta-adrenergic receptors.

Quantitative analysis of rat brain alpha 2-receptors discriminated by [3H]clonidine and [3H]rauwolscine.

PubMed

Asakura, M; Tsukamoto, T; Imafuku, J; Matsui, H; Ino, M; Hasegawa, K

1984-10-30

Quantitative analysis of direct ligand binding of both [3H]clonidine and [3H]rauwolscine to the rat cerebral cortex alpha 2-receptors indicates the existence of two affinity states of the same receptor populations. In the presence of Mn2+, the high affinity state of [3H]clonidine binding was increased, whereas the high affinity state of [3H]rauwolscine binding was reduced. By contrast, GTP in micromolar ranges caused a decrease of the agonist high affinity state and an increase of the antagonist high affinity state. The total receptor sites and the respective separate affinities for both radioligands were approximately equal to their control values under all conditions, indicating that Mn2+ and GTP modulate the proportion of the two affinity states of the receptor. These results can be incorporated into a two-step, ternary complex model involving a guanine nucleotide binding protein (N protein) for the agonist and antagonist interaction with the alpha 2-receptor. Furthermore, the effects of GTP on the interaction of both ligands with the two affinity states can be mimicked by EDTA. It is suggested that divalent cations induce the formation of the receptor-N protein binary complex showing high affinity for agonists and low affinity for antagonists.

Alpha-1A Adrenergic receptor activation increases inhibitory tone in CA1 hippocampus

PubMed Central

Hillman, Kristin L.; Lei, Saobo; Doze, Van A.

2009-01-01

The endogenous catecholamine norepinephrine (NE) exhibits anti-epileptic properties, however it is not well understood which adrenergic receptor (AR) mediates this effect. The aim of this study was to investigate α1-adrenergic receptor (AR) activation in region CA1 of the hippocampus, a subcortical structure often implicated in temporal lobe epilepsies. Using cell-attached and whole-cell recordings in rat hippocampal slices, we confirmed that selective α1-AR activation increases action potential firing in a subpopulation of CA1 interneurons. We found that this response is mediated via the α1A-AR subtype, initiated by sodium influx, and appears independent of second messenger signaling. In CA1 pyramidal cells, α1A-AR activation decreases activity due to increased pre-synaptic GABA and somatostatin release. Examination of post-synaptic receptor involvement revealed that while GABAA receptors mediate the majority of α1A-adrenergic effects on CA1 pyramidal cells, significant contributions are also made by GABAB and somatostatin receptors. Finally, to test whether α1A-AR activation could have potential therapeutic implications, we performed AR agonist challenges using two in vitro epileptiform models. When GABAA receptors were available, α1A-AR activation significantly decreased epileptiform bursting in CA1. Together, our findings directly link stimulation of the α1A-AR subtype to release of GABA and somatostatin at the single cell level and suggest that α1A-AR activation may represent one mechanism by which NE exerts anti-epileptic effects within the hippocampus. PMID:19201164

The expression, localization and function of α7 nicotinic acetylcholine receptor in rat corpus cavernosum.

PubMed

Faghir-Ghanesefat, Hedyeh; Rahimi, Nastaran; Yarmohammadi, Fatemeh; Mokhtari, Tahmineh; Abdollahi, Ali Reza; Ejtemaei Mehr, Shahram; Dehpour, Ahmad R

2017-12-01

Alpha7 nicotinic acetylcholine receptor (α7-nAChR), an emerging pharmacological target for a variety of medical conditions, is expressed in the most mammalian tissues with different effects. So, this study was designed to investigate the expression, localization and effect of α7-nAChR in rat corpus cavernosum (CC). Reverse transcription polymerase chain reaction (RT-PCR) revealed that α7-nAChR was expressed in rat CC and double immunofluorescence studies demonstrated the presence of α7-nAChR in corporal neurons. The rat CC segments were mounted in organ bath chambers and contracted with phenylephrine (0.1 μm -300 μm) to investigate the relaxation effect of electrical field stimulation (EFS,10 Hz) assessed in the presence of guanethidine (adrenergic blocker, 5 μm) and atropine (muscarinic cholinergic blocker, 1 μm) to obtain non-adrenergic non-cholinergic (NANC) response. Cumulative administration of nicotine significantly potentiated the EFS-induced NANC relaxation (-log EC50 = 7.5 ± 0.057). Whereas, the potentiated NANC relaxation of nicotine was significantly inhibited with different concentrations of methyllycaconitine citrate (α7-nAChR antagonist, P < 0.05) in preincubated strips. L-NAME (non-specific nitric oxide synthase inhibitor, 1 μm) completely blocked the neurogenic relaxation induced by EFS plus nicotine. To conclude α7-nAChR is expressed in rat CC and modulates the neurogenic relaxation response to nicotine. © 2017 Royal Pharmaceutical Society.

A beta1-adrenergic receptor CaM kinase II-dependent pathway mediates cardiac myocyte fetal gene induction.

PubMed

Sucharov, Carmen C; Mariner, Peter D; Nunley, Karin R; Long, Carlin; Leinwand, Leslie; Bristow, Michael R

2006-09-01

Beta-adrenergic signaling plays an important role in the natural history of dilated cardiomyopathies. Chronic activation of beta-adrenergic receptors (beta1-AR and beta2-AR) during periods of cardiac stress ultimately harms the failing heart by mechanisms that include alterations in gene expression. Here, we show that stimulation of beta-ARs with isoproterenol in neonate rat ventricular myocytes causes a "fetal" response in the relative activities of the human cardiac fetal and/or adult gene promoters that includes repression of the human and rat alpha-myosin heavy chain (alpha-MyHC) promoters with simultaneous activation of the human atrial natriuretic peptide (ANP) and rat beta-MyHC promoters. We also show that the promoter changes correlate with changes in endogenous gene expression as measured by mRNA expression. Furthermore, we show that these changes are specifically mediated by the beta1-AR, but not the beta2-AR, and are independent of alpha1-AR stimulation. We also demonstrate that the fetal gene response is independent of cAMP and protein kinase A, whereas inhibition of Ca2+/calmodulin-dependent protein kinase (CaMK) pathway blocks isoproterenol-mediated fetal gene program induction. Finally, we show that induction of the fetal program is dependent on activation of the L-type Ca2+ channel. We conclude that in neonatal rat cardiac myocytes, agonist-occupied beta1-AR mobilizes Ca2+ stores to activate fetal gene induction through cAMP independent pathways that involve CaMK.

Enhancement by vasopressin of adrenergic responses in human mesenteric arteries.

PubMed

Medina, P; Noguera, I; Aldasoro, M; Vila, J M; Flor, B; Lluch, S

1997-03-01

Vasopressin not only acts directly on blood vessels through V1-receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vitro and in vivo. The aim of the present study was to investigate whether subpressor concentrations of vasopressin could modify the constrictor responses to norepinephrine and electrical stimulation of the perivascular nerves in human mesenteric arteries. Human mesenteric artery rings (3-3.5 mm long, 0.8-1.2 mm OD) were obtained from 38 patients undergoing abdominal operations. The arterial rings were suspended in organ bath chambers for isometric recording of tension. Vasopressin (3 x 10(-11) M) enhanced the contractions elicited by electrical stimulation at 2, 4, and 8 Hz (by 100, 100, and 72%, respectively) and produced a leftward shift of the concentration-response curves to norepinephrine (half-maximal effective concentration decreased from 2.2 x 10(-6) to 5.0 x 10(-7) M; P < 0.05) without any alteration in maximal contractions. Vasopressin also potentiated KCl- and calcium-induced contractions. The V1-receptor antagonist 1-[beta-mercapto-beta,beta-cyclopentamethylenepropionic acid-2-O-methyl-tyrosine, 8-arginine]vasopressin (10(-6) M) prevented the potentiation evoked by vasopressin in all cases. The calcium antagonist nifedipine (10(-6) M) did not affect the potentiation of electrical stimulation and norepinephrine induced by vasopressin but abolished KCl-induced contractions. The results suggest that vasopressin, in addition to its direct vasoconstrictor effect, strongly potentiates the responses to adrenergic stimulation and KCl depolarization. Both the direct and indirect effects of vasopressin appear to be mediated by V1-receptor stimulation. The amplifying effect of vasopressin on constrictor responses may be relevant in those clinical situations characterized by increased plasma vasopressin levels.

Stimulation of the noradrenergic system during memory formation impairs extinction learning but not the disruption of reconsolidation.

PubMed

Soeter, Marieke; Kindt, Merel

2012-04-01

The noradrenergic system plays a critical role in the 'consolidation' of emotional memory. If we are to target 'reconsolidation' in patients with anxiety disorders, the noradrenergic strengthening of fear memory should not impair the disruption of reconsolidation. In Experiment I, we addressed this issue using a differential fear conditioning procedure allowing selective reactivation of one of two fear associations. First, we strengthened fear memory by administering an α(2)-adrenergic receptor antagonist (ie, yohimbine HCl; double-blind placebo-controlled study) 30 min before acquisition (time for peak value yohimbine HCl <1 h). Next, the reconsolidation of one of the fear associations was manipulated by administering a β-adrenergic receptor antagonist (ie, propranolol HCl) 90 min before its selective reactivation (time for peak value propranolol HCl <2 h). In Experiment II, we administered propranolol HCl after reactivation of the memory to rule out a possible effect of the pharmacological manipulation on the memory retrieval itself. The excessive release of noradrenaline during memory formation not only delayed the process of extinction 48 h later, but also triggered broader fear generalization. Yet, the β-adrenergic receptor blocker during reconsolidation selectively 'neutralized' the fear-arousing aspects of the noradrenergic-strengthened memory and undermined the generalization of fear. We observed a similar reduction in fear responding when propranolol HCl was administered after reactivation of the memory. The present findings demonstrate the involvement of noradrenergic modulation in the formation as well as generalization of human fear memory. Given that the noradrenergic strengthening of fear memory impaired extinction learning but not the disruption of reconsolidation, our findings may have implications for the treatment of anxiety disorders.

Differential involvement of 5-HT(1A) and 5-HT(1B/1D) receptors in human interferon-alpha-induced immobility in the mouse forced swimming test.

PubMed

Zhang, Hongmei; Wang, Wei; Jiang, Zhenzhou; Shang, Jing; Zhang, Luyong

2010-01-01

Although Interferon-alpha (IFN-alpha, CAS 9008-11-1) is a powerful drug in treating several viral infections and certain tumors, a considerable amount of neuropsychiatric side-effects such as depression and anxiety are an unavoidable consequence. Combination with the selective serotonin (5-HT) reuptake inhibitor (SSRI) fluoxetine (CAS 56296-78-7) significantly improved the situation. However, the potential 5-HT(1A) receptor- and 5-HT(1B) receptor-signals involved in the antidepressant effects are still unclear. The effects of 5-HT(1A) receptor- and 5-HT(1B) receptor signals were analyzed by using the mouse forced swimming test (FST), a predictive test of antidepressant-like action. The present results indicated that (1) fluoxetine (administrated intragastrically, 30 mg/kg; not subactive dose: 15 mg/kg) significantly reduced IFN-alpha-induced increase of the immobility time in the forced swimming test; (2) 5-HT(1A) receptor- and 5-HT(1B) receptor ligands alone or in combination had no effects on IFN-alpha-induced increase of the immobility time in the FST; (3) surprisingly, WAY 100635 (5-HT(1A) receptor antagonist, 634908-75-1) and 8-OH-DPAT(5-HT(1A) receptor agonist, CAS 78950-78-4) markedly enhanced the antidepressant effect of fluoxetine at the subactive dose (15 mg/kg, i. g.) on the IFN-alpha-treated mice in the FST. Further investigations showed that fluoxetine combined with WAY 100635 and 8-OH-DPAT failed to produce antidepressant effects in the FST. (4) Co-application of CGS 12066A (5-HT(1B) receptor agonist, CAS 109028-09-3) or GR 127935 (5-HT(1B/1D) receptor antagonist, CAS 148642-42-6) with fluoxetine had no synergistic effects on the IFN-alpha-induced increase of immobility time in FST. (5) Interestingly, co-administration of GR 127935, WAY 100635 and fluoxetine significantly reduced the IFN-alpha-induced increase in immobility time of FST, being more effective than co-administration of WAY 100635 and fluoxetine. All results suggest that (1) compared to the 5-HT(1B) receptor, the 5-HT(1A) receptor signal plays the dominant role in improving the anti-immobility effect of fluoxetine in the IFN-alpha-induced depression; (2) combination of the 5-HT(1A) antagonist with subactive fluoxetine can be helpful in IFN-alpha-induced depression treatment.

Sympathetic nerve stimulation induces local endothelial Ca2+ signals to oppose vasoconstriction of mouse mesenteric arteries

PubMed Central

Nausch, Lydia W. M.; Bonev, Adrian D.; Heppner, Thomas J.; Tallini, Yvonne; Kotlikoff, Michael I.

2012-01-01

It is generally accepted that the endothelium regulates vascular tone independent of the activity of the sympathetic nervous system. Here, we tested the hypothesis that the activation of sympathetic nerves engages the endothelium to oppose vasoconstriction. Local inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ signals (“pulsars”) in or near endothelial projections to vascular smooth muscle (VSM) were measured in an en face mouse mesenteric artery preparation. Electrical field stimulation of sympathetic nerves induced an increase in endothelial cell (EC) Ca2+ pulsars, recruiting new pulsar sites without affecting activity at existing sites. This increase in Ca2+ pulsars was blocked by bath application of the α-adrenergic receptor antagonist prazosin or by TTX but was unaffected by directly picospritzing the α-adrenergic receptor agonist phenylephrine onto the vascular endothelium, indicating that nerve-derived norepinephrine acted through α-adrenergic receptors on smooth muscle cells. Moreover, EC Ca2+ signaling was not blocked by inhibitors of purinergic receptors, ryanodine receptors, or voltage-dependent Ca2+ channels, suggesting a role for IP3, rather than Ca2+, in VSM-to-endothelium communication. Block of intermediate-conductance Ca2+-sensitive K+ channels, which have been shown to colocalize with IP3 receptors in endothelial projections to VSM, enhanced nerve-evoked constriction. Collectively, our results support the concept of a transcellular negative feedback module whereby sympathetic nerve stimulation elevates EC Ca2+ signals to oppose vasoconstriction. PMID:22140050

Influence of myocardial oxygen demand on the coronary vascular response to arterial blood gas changes in humans.

PubMed

Vermeulen, Tyler Dennis; Boulet, Lindsey M; Stembridge, Mike; Williams, Alexandra Mackenzie; Anholm, James D; Subedi, Prajan; Gasho, Chris; Ainslie, Philip N; Feigl, Eric O; Foster, Glen Edward

2018-03-30

It remains unclear if the human coronary vasculature is inherently sensitive to changes in arterial PO 2 and PCO 2 or if coronary vascular responses are the result of concomitant increases in myocardial O 2 consumption/demand (MVO 2 ). We hypothesized that the coronary vascular response to PO 2 and PCO 2 would be attenuated in healthy men when MVO 2 was attenuated with β 1 -adrenergic receptor blockade. Healthy men (n=11; age: 25 {plus minus} 1 years) received intravenous esmolol (β 1 -adrenergic receptor antagonist) or volume-matched saline in a double-blind, randomized, crossover study, and were exposed to poikilocapnic hypoxia, isocapnic hypoxia, and hypercapnic hypoxia. Measurements made at baseline and following 5-min of steady state at each gas manipulation included left anterior descending coronary blood velocity (LAD V ; Doppler echocardiography), heart rate and arterial blood pressure. LAD V values at the end of each hypoxic condition were compared between esmolol and placebo. Rate pressure product (RPP) and left-ventricular mechanical energy (ME LV ) were calculated as indices of MVO 2 . All gas manipulations augmented RPP, ME LV , and LAD V but only RPP and ME LV were attenuated (4-18%) following β 1 -adrenergic receptor blockade (P<0.05). Despite attenuated RPP and MELV responses, β 1 -adrenergic receptor blockade did not attenuate the mean LADV vasodilatory response when compared to placebo during poikilocapnic hypoxia (29.4{plus minus}2.2 vs. 27.3{plus minus}1.6 cm/s) and isocapnic hypoxia (29.5{plus minus}1.5 vs. 30.3{plus minus}2.2 cm/s). Hypercapnic hypoxia elicited a feed-forward coronary dilation that was blocked by β 1 -adrenergic receptor blockade. These results indicate a direct influence of arterial PO 2 on coronary vascular regulation that is independent of MVO 2 .

Alpha1-adrenergic blockers: current usage considerations.

PubMed

Sica, Domenic A

2005-12-01

Alpha1-adrenergic-blocking drugs are effective in reducing blood pressure and do so in a fashion comparable to most other antihypertensive drug classes. These compounds are most effective in patients in the upright position, reducing systolic and diastolic pressures by 8%-10%. Alpha1-adrenergic-blocking drugs incrementally reduce blood pressure when combined with most drug classes and are the only antihypertensive drug class to improve plasma lipid profiles. Alpha1-adrenergic-blocking drugs are also accepted as important elements of the treatment plan for symptomatic benign prostatic hypertrophy. Dose escalation of an alpha1-adrenergic-blocking drug can trigger renal Na+ retention, and the ensuing volume expansion can attenuate its blood pressure-lowering effect. Orthostatic hypotension can occur with these compounds, particularly when a patient is volume-contracted. Dizziness, headache, and drowsiness are common side effects with alpha1-adrenergic blockers. A modest decline in the use of doxazosin and other alpha1-adrenergic-blocking drugs has occurred coincident to the early termination of the doxazosin treatment arm in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial.

Agonist-induced modulation of inverse agonist efficacy at the beta 2-adrenergic receptor.

PubMed

Chidiac, P; Nouet, S; Bouvier, M

1996-09-01

Sustained stimulation of several G protein-coupled receptors is known to lead to a reduction in the signaling efficacy. This phenomenon, named agonist-induced desensitization, has been best studied for the beta 2-adrenergic receptor (AR) and is characterized by a decreased efficacy of beta-adrenergic agonists to stimulate the adenylyl cyclase activity. Recently, several beta-adrenergic ligands were found to inhibit the spontaneous agonist-independent activity of the beta 2AR. These compounds, termed inverse agonists, have different inhibitory efficacies, ranging from almost neutral antagonists to full inverse agonists. The current study was undertaken to determine whether, as is the case for agonists, desensitization can affect the efficacies of inverse agonists. Agonist-promoted desensitization of the human beta 2AR expressed in Sf9 cells potentiated the inhibitory actions of the inverse agonists, with the extent of the potentiation being inversely proportional to their intrinsic activity. For example, desensitization increased the inhibitory action of the weak inverse agonist labetalol by 29%, whereas inhibition of the spontaneous activity by the strong inverse agonist timolol was not enhanced by the desensitizing stimuli. Interestingly, dichloroisoproterenol acted stochastically as either a weak partial agonist or a weak inverse agonist in control conditions but always behaved as an inverse agonist after desensitization. These data demonstrate that like for agonists, the efficacies of inverse agonists can be modulated by a desensitizing treatment. Also, the data show that the initial state of the receptor can determine whether a ligand behaves as a partial agonist or an inverse agonist.

Evidence for Increased Beta-Adrenoreceptor Responsiveness Induced by 14 Days of Simulated Microgravity in Humans

NASA Technical Reports Server (NTRS)

Convertino, Victor A.; Polet, Jill L.; Engelke, Keith A.; Hoffler, G. W.; Lane, Lynda D.

1996-01-01

We studied hemodynamic responses to alpha and beta receptor agonists in 8 healthy men ( 38+- 2 yrs) before and after 14 days of 6 degree head-down tilt (HDT) to test the hypothesis that increased adrenergic responsiveness is induced by prolonged exposure to microgravity. Immediately following a 30-min baseline period, a steady-state infusion of isoproterenol (ISO) was used to assess beta 1- and beta 2-adrenergic responsiveness. ISO was infused at three graded constant rates of 0.005, 0.01 and 0.02 ug/kg/min. After heart rate and blood pressure had been allowed to return to baseline levels following ISO infusion graded infusion of phenylephrine (PE) was used to assess responsiveness of alpha I-vascular receptors. PE was infused at three graded constant rates of 0.25, 0.50 and 1.00 ug/kg/min. Each infusion interval for both drugs was 9 min. During the infusions, constant monitoring of beat-to-beat blood pressure and heart rate was performed and leg blood flow was measured with occlusion plethysmography at each infusion level. The slopes calculated from linear regressions between ISO and PE doses and changes in heart rate, blood pressure, and leg vascular resistance for each subject were used to represent alpha- and beta- adrenoreceptor responsiveness. Fourteen days HDT increased the slopes of heart rate (1056 +- 107 to 1553 +- 83 beats/ug/kg/min; P= 0.014) and vasodilation (-469ft +- 111 to -l446 +- 309 PRU/ug/kg/min; P =0.0224) to ISO infusion. There was no alteration in blood pressure or vascular resistance responses to PE infusion after HDT. Our results provide evidence that microgravity causes selective increases in beta 1- and beta 2-adrenergic responsiveness without affecting alpha 1-vascular responses.

Bidirectional Modulation of Alcohol-Associated Memory Reconsolidation through Manipulation of Adrenergic Signaling

PubMed Central

Schramm, Moritz J W; Everitt, Barry J; Milton, Amy L

2016-01-01

Alcohol addiction is a problem of great societal concern, for which there is scope to improve current treatments. One potential new treatment for alcohol addiction is based on disrupting the reconsolidation of the maladaptive Pavlovian memories that can precipitate relapse to drug-seeking behavior. In alcohol self-administering rats, we investigated the effects of bidirectionally modulating adrenergic signaling on the strength of a Pavlovian cue-alcohol memory, using a behavioral procedure that isolates the specific contribution of one maladaptive Pavlovian memory to relapse, the acquisition of a new alcohol-seeking response for an alcohol-associated conditioned reinforcer. The β-adrenergic receptor antagonist propranolol, administered in conjunction with memory reactivation, persistently disrupted the memory that underlies the capacity of a previously alcohol-associated cue to act as a conditioned reinforcer. By contrast, enhancement of adrenergic signaling by administration of the adrenergic prodrug dipivefrin at reactivation increased the strength of the cue-alcohol memory and potentiated alcohol seeking. These data demonstrate the importance of adrenergic signaling in alcohol-associated memory reconsolidation, and suggest a pharmacological target for treatments aiming to prevent relapse through the disruption of maladaptive memories. PMID:26279079

Crystal Structure of Oligomeric β1-Adrenergic G Protein- Coupled Receptors in Ligand-Free Basal State

PubMed Central

Huang, Jianyun; Chen, Shuai; Zhang, J. Jillian; Huang, Xin-Yun

2013-01-01

G protein-coupled receptors (GPCRs) mediate transmembrane signaling. Before ligand binding, GPCRs exist in a basal state. Crystal structures of several GPCRs bound with antagonists or agonists have been solved. However, the crystal structure of the ligand-free basal state of a GPCR, the starting point of GPCR activation and function, has not been determined. Here we report the X-ray crystal structure of the first ligand-free basal state of a GPCR in a lipid membrane-like environment. Oligomeric turkey β1-adrenergic receptors display two alternating dimer interfaces. One interface involves the transmembrane domain (TM) 1, TM2, the C-terminal H8, and the extracellular loop 1. The other interface engages residues from TM4, TM5, the intracellular loop 2 and the extracellular loop 2. Structural comparisons show that this ligand-free state is in an inactive conformation. This provides the structural information regarding GPCR dimerization and oligomerization. PMID:23435379

Evidence for the gastric cytoprotective effect of centrally injected agmatine.

PubMed

Zádori, Zoltán S; Tóth, Viktória E; Fehér, Ágnes; Philipp, Kirsch; Németh, József; Gyires, Klára

2014-09-01

Agmatine (decarboxylated arginine) exerts cytoprotective action in several tissues, such as in the brain, heart or kidneys, but there is still controversy over the effects of agmatine on the gastric mucosa. The aim of the present study was to reveal the potential gastroprotective action of agmatine by using an acid-independent ulcer model to clarify which receptors and peripheral factors are involved in it. Gastric mucosal damage was induced by acidified ethanol. Mucosal levels of calcitonin gene-related peptide (CGRP) and somatostatin were determined by radioimmunoassay. For analysis of gastric motor activity the rubber balloon method was used. It was found that agmatine given intracerebroventricularly (i.c.v., 0.044-220 nmol/rat) significantly inhibited the development of ethanol-induced mucosal damage, while in the case of intraperitoneal injection (0.001-50mg/kg i.p.) it had only a minor effect. The central gastroprotective action of agmatine was completely antagonized by mixed alpha2-adrenoceptor and imidazoline I1 receptor antagonists (idazoxan, efaroxan), but only partially by yohimbine (selective alpha2-adrenoceptor antagonist) and AGN 192403 (selective I1 receptor ligand, putative antagonist). It was also inhibited by the non-selective opioid-receptor antagonist naloxone and the selective δ-opioid receptor antagonist naltrindole, but not by β-funaltrexamine and nor-Binaltorphimine (selective μ- and κ-opioid receptor antagonists, respectively). Furthermore, the effect of agmatine was antagonized by bilateral cervical vagotomy and by pretreatment with indomethacin and NG-nitro-l-arginine. Agmatine also reversed the ethanol-induced reduction of gastric mucosal CGRP and somatostatin content, but did not have any significant effect on gastric motor activity. These results indicate that agmatine given centrally induces gastric cytoprotection, which is mediated by central imidazoline I1 receptors, alpha2-adrenoceptors and δ-opioid receptors. Activation of these receptors induces the release of different mucosal protective factors, such as NO, prostaglandins, CGRP and somatostatin by a vagal-dependent mechanism. Alterations of gastric motility are not likely to contribute to the observed protective effect. Copyright © 2014 Elsevier Inc. All rights reserved.

Regulation of G-protein coupled receptor traffic by an evolutionary conserved hydrophobic signal.

PubMed

Angelotti, Tim; Daunt, David; Shcherbakova, Olga G; Kobilka, Brian; Hurt, Carl M

2010-04-01

Plasma membrane (PM) expression of G-protein coupled receptors (GPCRs) is required for activation by extracellular ligands; however, mechanisms that regulate PM expression of GPCRs are poorly understood. For some GPCRs, such as alpha2c-adrenergic receptors (alpha(2c)-ARs), heterologous expression in non-native cells results in limited PM expression and extensive endoplasmic reticulum (ER) retention. Recently, ER export/retentions signals have been proposed to regulate cellular trafficking of several GPCRs. By utilizing a chimeric alpha(2a)/alpha(2c)-AR strategy, we identified an evolutionary conserved hydrophobic sequence (ALAAALAAAAA) in the extracellular amino terminal region that is responsible in part for alpha(2c)-AR subtype-specific trafficking. To our knowledge, this is the first luminal ER retention signal reported for a GPCR. Removal or disruption of the ER retention signal dramatically increased PM expression and decreased ER retention. Conversely, transplantation of this hydrophobic sequence into alpha(2a)-ARs reduced their PM expression and increased ER retention. This evolutionary conserved hydrophobic trafficking signal within alpha(2c)-ARs serves as a regulator of GPCR trafficking.

Activation of cholinergic receptors blocks non-adrenergic non-cholinergic contractions in the rat urinary bladder

PubMed Central

Henry Lai, H.; Smith, Christopher P.; Munoz, Alvaro; Boone, Timothy B.; Szigeti, Gyula P.; Somogyi, George T.

2008-01-01

In the present study, the plasticity of the non-adrenergic non-cholinergic (NANC) response was investigated. Isolated rat bladder strips were electrically stimulated and the evoked contractions were isometrically recorded. The NANC part of the contractions were unmasked by applying 500 nM 4-DAMP, a potent muscarinic antagonist. Treatment of the bladder strips with 10 μM carbachol (a cholinergic agonist) increased the muscle tone but did not alter the neurally evoked contractions. However, carbachol decreased: (1) the NANC response from 74.6% to 33.3% of control and (2) the purinergic contractile response to α,β methylene ATP (α,β mATP) (10 μM) from 97.0% to 43.4% (p<0.05). Treatment with the cholinesterase inhibitor eserine (10 μM) also significantly decreased the NANC response to 21.1% (p<0.0001). The purinergic receptor antagonist suramin (100μM) did not affect the neurally evoked contractions, however; subsequent addition of 4-DAMP decreased the contractions to 31%. Activation of the smooth muscle cholinergic receptors (with carbachol or eserine) and purinergic receptors (with α,β mATP) decreased the NANC contractions and the direct contractile response to α,β mATP. When the electrically evoked contractions were facilitated by the L-type Ca2+ channel activator, Bay-K 8644 the subsequent application of 4-DAMP did not unmask inhibited NANC contractions. We conclude that activation of muscarinic receptors by cholinergic agonist, carbachol or by endogenous acetylcholine (ACh) induce a cascade of events that leads to diminished purinergic response and consequently an inhibition of the bladder NANC response. PMID:18755252

Effects of co-treatment with mirtazapine and low doses of risperidone on immobility time in the forced swimming test in mice.

PubMed

Rogóż, Zofia

2010-01-01

The aim of the present study was to examine the effect of mirtazapine (MIR) and risperidone (an atypical antipsychotic drug), given separately or jointly, on immobility time in the forced swimming test in male C57BL/6J mice. Fluoxetine (FLU) was used as a reference drug. MIR (2.5, 5 and 10 mg/kg) and FLU (5 and 10 mg/kg), or risperidone in low doses (0.05 and 0.1 mg/kg) given alone did not change the immobility time of mice in the forced swimming test. Joint administration of MIR (5 and 10 mg/kg) or FLU (10 mg/kg) and risperidone (0.1 mg/kg) produced antidepressant-like activity in the forced swimming test. WAY100636 (a 5-HT(1A) receptor antagonist) inhibited, while yohimbine (an α(2)-adrenergic receptor antagonist) potentiated the antidepressant-like effect induced by co-administration of MIR and risperidone. Active behavior in that test did not reflect an increase in general activity, since combined administration of antidepressants and risperidone failed to enhance the locomotor activity of mice. The obtained results indicate that risperidone applied in a low dose enhances the antidepressant-like activity of MIR and that, among other mechanisms, 5-HT(1A)-, and α(2)-adrenergic receptors may play a role in this effect.

Functional selectivity of GPCR-directed drug action through location bias

PubMed Central

Irannejad, Roshanak; Pessino, Veronica; Mika, Delphine; Huang, Bo; Wedegaertner, Philip B.; Conti, Marco; von Zastrow, Mark

2017-01-01

G protein-coupled receptors (GPCRs) are increasingly recognized to operate from intracellular membranes as well as the plasma membrane. The β2-adrenergic GPCR can activate Gs-linkedcyclic AMP (cAMP) signaling from endosomes. We show here that the homologous human β1-adrenergic receptor initiates an internal Gs-cAMP signal from the Golgi apparatus. By developing a chemical method to acutely squelch G protein coupling at defined membrane locations, we demonstrate that Golgi activation contributes significantly to the overall cellular cAMP response. Golgi signalling utilizes a pre-existing receptor pool rather than receptors delivered from the cell surface, requiring separate access of extracellular ligands. Epinephrine, a hydrophilic endogenous ligand, accesses the Golgi-localized receptor pool by facilitated transport requiring the organic cation transporter 3 (OCT3) whereas drugs can access the Golgi pool by passive diffusion according to hydrophobicity. We demonstrate marked differences among both agonist and antagonist drugs in Golgi-localized receptor access, and show that β-blocker drugs presently used in the clinic differ markedly in ability to antagonize the Golgi signal. We propose ’location bias’ as a new principle for achieving functional selectivity of GPCR-directed drug action. PMID:28553949

Transmembrane Segment Five Serines of the D4 Dopamine Receptor Uniquely Influence the Interactions of Dopamine, Norepinephrine, and Ro10-4548

PubMed Central

Cummings, David F.; Ericksen, Spencer S.; Goetz, Angela

2010-01-01

Conserved serines of transmembrane segment (TM) five (TM5) are critical for the interactions of endogenous catecholamines with α1- and α2-adrenergic, β2-adrenergic, and D1, D2, and D3 dopamine receptors. The unique high-affinity interaction of the D4 dopamine receptor subtype with both norepinephrine and dopamine, and the fact that TM5 serine interactions have never been studied for this receptor subtype, led us to investigate the interactions of ligands with D4 receptor TM5 serines. Serine-to-alanine mutations at positions 5.42 and 5.46 drastically decreased affinities of dopamine and norepinephrine for the D4 receptor. The D4-S5.43A receptor mutant had substantially reduced affinity for norepinephrine, but a modest loss of affinity for dopamine. In functional assays of cAMP accumulation, norephinephrine was unable to activate any of the mutant receptors, even though the agonist quinpirole displayed wild-type functional properties for all of them. Dopamine was unable to activate the S5.46A mutant and had reduced potency for the S5.43A mutant and reduced potency and efficacy for the S5.42A mutant. In contrast, Ro10-4548 [RAC-2′-2-hydroxy-3-4-(4-hydroxy-2-methoxyphenyl)-1-piperazinyl-propoxy-acetanilide], a catechol-like antagonist of the wild-type receptor unexpectedly functions as an agonist of the S5.43A mutant. Other noncatechol ligands had similar properties for mutant and wild-type receptors. This is the first example of a dopamine receptor point mutation selectively changing the receptor's interaction with a specific antagonist to that of an agonist, and together with other data, provides evidence, supported by molecular modeling, that catecholamine-type agonism is induced by different ligand-specific configurations of intermolecular H-bonds with the TM5 conserved serines. PMID:20215412

Exogenous NO administration and alpha-adrenergic vasoconstriction in human limbs.

PubMed

Rosenmeier, Jaya B; Fritzlar, Sandy J; Dinenno, Frank A; Joyner, Michael J

2003-12-01

Nitric oxide (NO) is capable of blunting alpha-adrenergic vasoconstriction in contracting skeletal muscles of experimental animals (functional sympatholysis). We therefore tested the hypothesis that exogenous NO administration can blunt alpha-adrenergic vasoconstriction in resting human limbs by measuring forearm blood flow (FBF; Doppler ultrasound) and blood pressure in eight healthy males during brachial artery infusions of three alpha-adrenergic constrictors (tyramine, which evokes endogenous norepinephrine release; phenylephrine, an alpha1-agonist; and clonidine, an alpha2-agonist). To simulate exercise hyperemia, the vasoconstriction caused by the alpha-agonists was compared during adenosine-mediated (>50% NO independent) and sodium nitroprusside-mediated (SNP; NO donor) vasodilation of the forearm. Both adenosine and SNP increased FBF from approximately 35-40 to approximately 200-250 ml/min. All three alpha-adrenergic constrictor drugs caused marked reductions in FBF and calculated forearm vascular conductance (P < 0.05). The relative reductions in forearm vascular conductance caused by the alpha-adrenergic constrictors during SNP infusion were similar (tyramine, -74 +/- 3 vs. -65 +/- 2%; clonidine, -44 +/- 6 vs. -44 +/- 6%; P > 0.05) or slightly greater (phenylephrine, -47 +/- 6 vs. -33 +/- 6%; P < 0.05) compared with the responses during adenosine. In conclusion, these results indicate that exogenous NO sufficient to raise blood flow to levels simulating those seen during exercise does not blunt alpha-adrenergic vasoconstriction in the resting human forearm.

Involvement of adrenergic and serotonergic nervous mechanisms in allethrin-induced tremors in mice.

PubMed

Nishimura, M; Obana, N; Yagasaki, O; Yanagiya, I

1984-05-01

Oral or intravenous administration of allethrin, a synthetic derivative of the pirethrin-based insecticides, produces neurotoxic symptoms consisting of mild salivation, hyperexcitability, tremors and convulsions which result in death. Intracerebroventricular injection of allethrin to mouse at about one-nineth the dose of intravenous administration, produced qualitatively identical but less prominent symptoms, indicating that at least some of the symptoms may be originated in the central nervous system. To investigate the mechanism of action of the compound, we studied the ability of agents which alter neurotransmission to prevent or potentiate the effect of convulsive doses of technical grade (15.5% cis, 84.5% trans) allethrin. Intraperitoneal pretreatment with drugs which block noradrenergic receptors or norepinephrine synthesis, such as pentobarbital, chlorpromazine, phentolamine, phenoxybenzamine and reserpine, depressed the tremor induced by allethrin. The inhibitory effect of reserpine was reversed by phenylephrine. Both the serotonergic blocker, methysergide, and the serotonin depletor, rho-chlorphenylalanine, potentiated the effect of allethrin. The potentiating effect of methysergide was antagonized by 5-hydroxytryptamine. However, intracerebroventricular administration of methysergide was ineffective in potentiating the effect of allethrin. alpha 2- and beta-adrenoceptor blockers, muscarinic antagonists, GABA mimenergics and morphine had no effect. These results suggest that allethrin produces its neurotoxic responses in mice by acting on the brain and spinal levels. Furthermore, adrenergic excitatory and serotonergic inhibitory mechanisms may be involved in the neural pathway through which the allethrin-induced tremor is evoked.

SRD5A1 and SRD5A2 are associated with treatment for benign prostatic hyperplasia with the combination of 5α-reductase inhibitors and α-adrenergic receptor antagonists.

PubMed

Gu, Xin; Na, Rong; Huang, Tao; Wang, Li; Tao, Sha; Tian, Lu; Chen, Zhuo; Jiao, Yang; Kang, Jian; Zheng, Siqun; Xu, Jianfeng; Sun, Jielin; Qi, Jun

2013-08-01

Common treatments for benign prostatic hyperplasia include 5α-reductase inhibitors and α-adrenergic receptor antagonists. However, these treatments can only partially decrease the risk of benign prostatic hyperplasia progression. SRD5A1 and SRD5A2 are 5α-reductase inhibitor targets. We investigated the association between drug efficacy and single nucleotide polymorphisms in the SRD5A1 and SRD5A2 genes in a Chinese population. We genotyped 11 tagging single nucleotide polymorphisms in the SRD5A1 and SRD5A2 genes in a total of 426 benign prostatic hyperplasia cases and 1,008 controls from Xinhua Hospital, Shanghai, People's Republic of China. Cases were treated with type II 5α-reductase inhibitors and α-adrenergic receptor antagonists. We tested the association of tagging single nucleotide polymorphisms with benign prostatic hyperplasia risk/progression, clinical characteristics at baseline, including the I-PSS (International Prostate Symptom Score) and total prostate volume, and changes in clinical characteristics after treatment. The 11 tagging single nucleotide polymorphisms were not significantly associated with benign prostatic hyperplasia risk or progression (each p >0.05). In the SRD5A1 gene rs6884552 and rs3797177 were significantly associated with baseline I-PSS (p = 0.04 and 0.003, respectively). In the SRD5A2 gene rs523349 (V89L) and rs9332975 were significantly associated with baseline total prostate volume (p = 0.01 and 0.001, respectively). In SRD5A1 rs166050 was significantly associated with the posttreatment change in total prostate volume (p = 0.04). In SRD5A2 rs523349 and rs612224 were significantly associated with the posttreatment I-PSS change (p = 0.03 and 0.009, respectively). SRD5A1 and SRD5A2 single nucleotide polymorphisms are significantly associated with the clinical characteristics of benign prostatic hyperplasia and the efficacy of benign prostatic hyperplasia treatment. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Differences in potency and efficacy of a series of phenylisopropylamine/phenylethylamine pairs at 5-HT(2A) and 5-HT(2C) receptors.

PubMed

Acuña-Castillo, Claudio; Villalobos, Claudio; Moya, Pablo R; Sáez, Patricio; Cassels, Bruce K; Huidobro-Toro, J Pablo

2002-06-01

The pharmacological profile of a series of (+/-)-2,5-dimethoxy-4-(X)-phenylisopropylamines (X=I, Br, NO(2), CH(3), or H) and corresponding phenylethylamines, was determined in Xenopus laevis oocytes injected with cRNA coding for rat 5-HT(2A) or 5-HT(2C) receptors. The efficacy and relative potency of these drugs were determined and compared to classical 5-HT(2) receptor agonists and antagonists. The rank order of agonist potency at the 5-HT(2A) receptor was: alpha-methyl-5-HT=5-HT>m-CPP>MK-212; at the 5-HT(2C) receptor the order was: 5-HT>alpha-methyl-5-HT>MK-212>m-CPP. All these compounds were full agonists at the 5-HT(2C) receptor, but alpha-methyl-5-HT and m-CPP showed lower efficacy at the 5-HT(2A) receptor. 4-(4-Fluorobenzoyl)-1-(4-phenylbutyl)piperidine (4F 4PP) was 200 times more potent as a 5-HT(2A) antagonist than at 5-HT(2C) receptors. Conversely, RS 102221 was 100 times more potent as a 5-HT(2C) antagonist, confirming their relative receptor selectivities. The phenylisopropylamines were partial agonists at the 5-HT(2A) receptor, with I(max) relative to 5-HT in the 22+/-7 to 58+/-15% range; the corresponding phenylethylamines had lower or undetectable efficacies. All these drugs had higher efficacies at 5-HT(2C) receptors; DOI was a full 5-HT(2C) agonist. 2C-I and the other phenylethylamines examined showed relative efficacies at the 5-HT(2C) receptor ranging from 44+/-10% to 76+/-16%. 2C-N was a 5-HT(2) receptor antagonist; the mechanism was competitive at the 5-HT(2A), but non-competitive at the 5-HT(2C) receptor. The antagonism was time-dependent at the 5-HT(2C) receptor but independent of pre-incubation time at the 5-HT(2A) receptor subtype. The alpha-methyl group determines the efficacy of these phenylalkylamines at the 5-HT(2A) and 5-HT(2C) receptors.

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 β 1 -adrenergic receptor (β 1 AR) 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 β 1 AR 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 β 1 AR 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 β 1 AR. 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 β 1 AR regulation that may open up possibilities for new therapeutic strategies for cardiovascular diseases. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Prostaglandins, steroids and reception (an attempt to model the structure of the active centers of adrenoreception).

PubMed

Podymov, V K; Piruzyan, L A; Gladkikh, S P; Kats, M M; Nizhnii, S V

1980-01-01

On the basis of numerous results of investigations on adrenergic systems, an orientational model of the adrenoreceptor (AR) is postulated. Its active center includes low-molecular-weight components--prostaglandins (PGE, PGF), steroids (cortisone, hydrocortisone), S+-adenosylmethionine, Ca, Mg, and Mn ions. Appraisal of the stereospecific characteristics of such a functional unit of AR explains the difference in the nature and magnitude of the effects of interaction of the catecholamines, their agonists and antagonists will the so-called alpha- and beta-AR. Depending on the organ or tissue in which the AR is located, its protein subunits comprise adenylcyclase (beta-AR) or Na,K-ATPase (alpha-AR). An obligatory component of the AR is catechol-O-methyltransferase. The model elaborated describes satisfactorily the molecular mechanisms of action of many pharmacological agents, explains why attempts to isolate and reconstruct the AR have proved fruitless, and gives grounds for rejecting the hypothesis that there exist steroid, prostaglandin, and purinergic receptors, linking the exceptionally high and diverse activity of these biologically active substances with their participation in adrenoreception among other reasons. A conception of the active centers of the AR as low-molecular-weight entities permits the explanation of such phenomena as the desensitization of the AR, the "interconversion" of beta-AR into alpha-AR with a change in the parameters of the medium, and certain components of the pathogenesis of bronchial asthma, etc.

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.

Receptor protection studies comparing recombinant and native nicotinic receptors: Evidence for a subpopulation of mecamylamine-sensitive native alpha3beta4* nicotinic receptors.

PubMed

Free, R Benjamin; Kaser, Daniel J; Boyd, R Thomas; McKay, Dennis B

2006-01-09

Studies involving receptor protection have been used to define the functional involvement of specific receptor subtypes in tissues expressing multiple receptor subtypes. Previous functional studies from our laboratory demonstrate the feasibility of this approach when applied to neuronal tissues expressing multiple nicotinic acetylcholine receptors (nAChRs). In the current studies, the ability of a variety of nAChR agonists and antagonists to protect native and recombinant alpha3beta4 nAChRs from alkylation were investigated using nAChR binding techniques. Alkylation of native alpha3beta4* nAChRs from membrane preparations of bovine adrenal chromaffin cells resulted in a complete loss of specific [(3)H]epibatidine binding. This loss of binding to native nAChRs was preventable by pretreatment with the agonists, carbachol or nicotine. The partial agonist, cytisine, produced partial protection. Several nAChR antagonists were also tested for their ability to protect. Hexamethonium and decamethonium were without protective activity while mecamylamine and tubocurarine were partially effective. Addition protection studies were performed on recombinant alpha3beta4 nAChRs. As with native alpha3beta4* nAChRs, alkylation produced a complete loss of specific [(3)H]epibatidine binding to recombinant alpha3beta4 nAChRs which was preventable by pretreatment with nicotine. However, unlike native alpha3beta4* nAChRs, cytisine and mecamylamine, provide no protection for alkylation. These results highlight the differences between native alpha3beta4* nAChRs and recombinant alpha3beta4 nAChRs and support the use of protection assays to characterize native nAChR subpopulations.

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

PubMed

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

2016-08-01

Postganglionic sympathetic neurons innervate secondary lymphoid organs and secrete norepinephrine (NE) as the primary neurotransmitter. NE binds and signals through five distinct members of the adrenergic receptor family. In this study, we show elevated expression of the β2-adrenergic receptor (ADRB2) on primary human CD8(+) effector memory T cells. Treatment of both human and murine CD8(+) T cells with NE decreased IFN-γ and TNF-α secretion and suppressed their cytolytic capacity in response to T-cell receptor (TCR) activation. The effects of NE were specifically reversed by β2-specific antagonists. Adrb2(-/-) CD8(+) T cells were completely resistant to the effects of NE. Further, the ADRB2-specific pharmacological ligand, albuterol, significantly suppressed effector functions in both human and mouse CD8(+) T cells. While both TCR activation and stimulation with IL-12 + IL-18 were able to induce inflammatory cytokine secretion, NE failed to suppress IFN-γ secretion in response to IL-12 + IL18. Finally, the long-acting ADRB2-specific agonist, salmeterol, markedly reduced the cytokine secretion capacity of CD8(+) T cells in response to infection with vesicular stomatitis virus. This study reveals a novel intrinsic role for ADRB2 signaling in CD8(+) T-cell function and underscores the novel role this pathway plays in adaptive T-cell responses to infection. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gintonin enhances performance of mice in rotarod test: Involvement of lysophosphatidic acid receptors and catecholamine release.

PubMed

Lee, Byung-Hwan; Kim, Jisu; Lee, Ra Mi; Choi, Sun-Hye; Kim, Hyeon-Joong; Hwang, Sung-Hee; Lee, Myung Koo; Bae, Chun-Sik; Kim, Hyoung-Chun; Rhim, Hyewon; Lim, Kiwon; Nah, Seung-Yeol

2016-01-26

Ginseng has a long history of use as a tonic for restoration of vigor. One example of ginseng-derived tonic effect is that it can improve physical stamina under conditions of stress. However, the active ingredient and the underlying molecular mechanism responsible for the ergogenic effect are unknown. Recent studies show that ginseng contains a novel ingredient, gintonin, which consists of a unique class of herbal-medicine lysophosphatidic acids (LPAs). Gintonin activates G protein-coupled LPA receptors to produce a transient [Ca(2+)]i signal, which is coupled to diverse intra- and inter-cellular signal transduction pathways that stimulate hormone or neurotransmitter release. However, relatively little is known about how gintonin-mediated cellular modulation is linked to physical endurance. In the present study, systemic administration of gintonin, but not ginsenosides, in fasted mice increased blood glucose concentrations in a dose-dependent manner. Gintonin treatment elevated blood glucose to a maximum level after 30min. This elevation in blood glucose level could be abrogated by the LPA1/3 receptor antagonist, Ki16425, or the β-adrenergic receptor antagonist, propranolol. Furthermore, gintonin-dependent enhanced performance of fasted mice in rotarod test was likewise abrogated by Ki16425. Gintonin also elevated plasma epinephrine and norepinephrine concentrations. The present study shows that gintonin mediates catecholamine release through activation of the LPA receptor and that activation of the β-adrenergic receptor is coupled to liver glycogenolysis, thereby increasing the supply of glucose and enhancing performance in the rotarod test. Thus, gintonin acts via the LPA-catecholamine-glycogenolysis axis, representing a candidate mechanism that can explain how ginseng treatment enhances physical stamina. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The amphiphilic peptide adenoregulin enhances agonist binding to A1-adenosine receptors and [35S]GTP gamma S to brain membranes.

PubMed

Moni, R W; Romero, F S; Daly, J W

1995-08-01

1. Adenoregulin is an amphilic peptide isolated from skin mucus of the tree frog, Phyllomedusa bicolor. Synthetic adenoregulin enhanced the binding of agonists to several G-protein-coupled receptors in rat brain membranes. 2. The maximal enhancement of agonist binding, and in parentheses, the concentration of adenoregulin affording maximal enhancement were as follows: 60% (20 microM) for A1-adenosine receptors, 30% (100 microM) for A2a-adenosine receptors, 20% (2 microM) for alpha 2-adrenergic receptors, and 30% (10 microM) for 5HT1A receptors. High affinity agonist binding for A1-, alpha 2-, and 5HT1A-receptors was virtually abolished by GTP gamma S in the presence of adenoregulin, but was only partially abolished in its absence. Magnesium ions increased the binding of agonists to receptors and reduced the enhancement elicited by adenoregulin. 3. The effect of adenoregulin on binding of N6-cyclohexyladenosine ([3H]CHA) to A1-receptors was relatively slow and was irreversible. Adenoregulin increased the Bmax value for [3H]CHA binding sites, and the proportion of high affinity states, and slowed the rate of [3H]CHA dissociation. Binding of the A1-selective antagonist, [3H]DPCPX, was maximally enhanced by only 13% at 2 microM adenoregulin. Basal and A1-adenosine receptor-stimulated binding of [35S]GTP gamma S were maximally enhanced 45% and 23%, respectively, by 50 microM adenoregulin. In CHAPS-solubilized membranes from rat cortex, the binding of both [3H]CHA and [3H]DPCPX were enhanced by adenoregulin. Binding of [3H]CHA to membranes from DDT1 MF-2 cells was maximally enhanced 17% at 20 microM adenoregulin. In intact DDT1 MF-2 cells, 20 microM adenoregulin did not potentiate the inhibition of cyclic AMP accumulation mediated via the adenosine A1 receptor. 4. It is proposed that adenoregulin enhances agonist binding through a mechanism involving enhancement of guanyl nucleotide exchange at G-proteins, resulting in a conversion of receptors into a high affinity state complexed with guanyl nucleotide-free G-protein.

Substance P is a functional neurotransmitter in the rat parotid gland.

PubMed

Gallacher, D V

1983-09-01

The technique of electrical field stimulation was employed to stimulate the intrinsic nerves of isolated rat parotid gland fragments. Responses to field stimulation were recorded as changes in enzyme secretion (amylase release), radiolabelled ion fluxes (86Rb efflux) and electrophysiological effects (changes in acinar cell membrane potential and input resistance). All effects of field stimulation were abolished by the neurotoxin, tetrodotoxin (TTX). Selective use of pharmacological antagonists revealed that both the sympathetic and parasympathetic nerves to this tissue were being excited by field stimulation. Importantly a significant component of the response to field stimulation persisted in the presence of combined autonomic receptor blockade by atropine, phentolamine and propranolol, i.e. due to release of a non-cholinergic, non-adrenergic neurotransmitter. The non-cholinergic, non-adrenergic neurotransmitter evoked amylase release, 86Rb efflux and electrophysiological effects seen as changes in acinar cell membrane potential and conductance, i.e. stimulus-permeability coupled. Two biologically active peptides, substance P (SP) and vasoactive intestinal polypeptide (VIP) were shown to evoke amylase release in the presence of combined autonomic blockade. VIP however did not evoke any increase in 86Rb efflux, i.e. not stimulus-permeability coupled. All the effects of the non-cholinergic, non-adrenergic transmitter were mimicked by substance P which evokes 86Rb efflux and electrophysiological effects in addition to amylase release. The non-cholinergic, non-adrenergic field stimulus effects on amylase release and 86Rb efflux were abolished or markedly attenuated in tissues which had been desensitized by prior exposure to exogenous substance P. In the presence of VIP, however, the non-cholinergic, non-adrenergic effects persisted and were apparently potentiated. Acute application of the neurotoxin capsaicin first stimulated a transient release of amylase and subsequently abolished the non-cholinergic, non-adrenergic field stimulus-evoked enzyme release. The putative substance P antagonist, D-Pro2, D-Trp7,9 substance P, reversibly blocked the response to both non-cholinergic, non-adrenergic nerve stimulation and exogenous substance P. It was demonstrated however that prolonged exposure to this antagonist is associated with non-reversible and, importantly, non-specific neurotoxic effects. It is concluded that substance P or a closely related peptide is a functional neurotransmitter in the rat parotid gland.

The common Arg389gly ADRB1 polymorphism affects heart rate response to the ultra-short-acting β(1) adrenergic receptor antagonist esmolol in healthy individuals.

PubMed

Muszkat, Mordechai; Hoofien, Assaf; Orlanski-Meyer, Esther; Makhoul, Hani; Porat, Einav; Davidson, Eliad M; Blotnick, Simcha; Caraco, Yoseph

2013-01-01

The β1-adrenergic receptor (β1AR) Arg389Gly polymorphism affects responses to orally administered β1AR antagonists (β-blockers) in vivo. However, the effect of this polymorphism on the early heart rate response to β-blockers has not been evaluated. The aim of this study was to determine the effect of the Arg389Gly polymorphism on the inhibition of exercise-induced tachycardia by esmolol, an ultra-short-acting intravenously administered β1AR antagonist. Healthy nonsmoking White individuals were enrolled on the basis of their ADRB1 genotype, including carriers of 0, 1 or 2 Arg389 alleles (n=9 in each group, total 27, 18 men). Placebo and esmolol were infused consecutively for 10 min each, separated by 30 min. At the end of each infusion, participants performed dynamic handgrip exercise. Heart rate and blood pressure were compared among three ADRB1 genotypes. Carriers of 0, 1, or 2 Arg389 alleles varied significantly in both exercise-induced tachycardia during esmolol (P(ANOVA)=0.030) and esmolol inhibition of exercise-induced tachycardia [0.78±7.70, 5.11±4.05, 10.22±9.78 bpm, respectively (P=0.014)]. The early effect of esmolol on exercise-induced tachycardia was significantly greater among Arg389 than in Gly389 homozygote healthy individuals (NCT01388036). © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Norepinephrine regulates cocaine-primed reinstatement via α1-adrenergic receptors in the medial prefrontal cortex.

PubMed

Schmidt, Karl T; Schroeder, Jason P; Foster, Stephanie L; Squires, Katherine; Smith, Brilee M; Pitts, Elizabeth G; Epstein, Michael P; Weinshenker, David

2017-06-01

Drug-primed reinstatement of cocaine seeking in rats is thought to reflect relapse-like behavior and is mediated by the integration of signals from mesocorticolimbic dopaminergic projections and corticostriatal glutamatergic innervation. Cocaine-primed reinstatement can also be attenuated by systemic administration of dopamine β-hydroxylase (DBH) inhibitors, which prevent norepinephrine (NE) synthesis, or by α1-adrenergic receptor (α1AR) antagonists, indicating functional modulation by the noradrenergic system. In the present study, we sought to further discern the role of NE in cocaine-seeking behavior by determining whether α1AR activation can induce reinstatement on its own or is sufficient to permit cocaine-primed reinstatement in the absence of all other AR signaling, and identifying the neuroanatomical substrate within the mesocorticolimbic reward system harboring the critical α1ARs. We found that while intracerebroventricular infusion of the α1AR agonist phenylephrine did not induce reinstatement on its own, it did overcome the blockade of cocaine-primed reinstatement by the DBH inhibitor nepicastat. Furthermore, administration of the α1AR antagonist terazosin in the medial prefrontal cortex (mPFC), but not the ventral tegmental area (VTA) or nucleus accumbens (NAc) shell, attenuated cocaine-primed reinstatement. Combined, these data indicate that α1AR activation in the mPFC is required for cocaine-primed reinstatement, and suggest that α1AR antagonists merit further investigation as pharmacotherapies for cocaine dependence. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-voltage electroencephalogram spindles in rats, aging and 5-HT2 antagonism.

PubMed

Moyanova, S; Kortenska, L; Kirov, R

1998-03-09

We examined the effects of serotonin-2 (5-hydroxytryptamine-2, 5-HT2) receptor antagonists on the so-called high-voltage spindles (HVS, electroencephalographic patterns, characterized by large amplitude rhythmic waves mainly in the alpha band), recorded from the frontal cortex of young, middle-aged and old freely-moving rats during waking immobility. The study was based on the assumption that the effects of 5-HT2 receptor antagonists on the HVS activity depend on the age of rats, because there is evidence for an age-related decrease in the 5-HT2 binding sites density. Four parameters of the electroencephalogram (EEG) were used to characterize the HVS activity: the square root-transformed EEG peak power in the alpha band, the frequency corresponding to this peak (both measured from the EEG power spectra using the fast Fourier transform), the HVS mean duration, and the HVS incidence (both measured from the EEG records). The EEG parameters were analyzed after i.p. administration of three 5-HT2 receptor antagonists: ketanserin, ritanserin and cyproheptadine. In young rats, the three drugs increased the alpha power, but did not change the alpha peak-corresponding frequency. Ketanserin and ritanserin did not change the HVS mean duration and HVS incidence, while cyproheptadine increased both these parameters in young rats. In middle-aged and old untreated rats, the HVS activity was significantly increased. The three 5-HT2 antagonists did not change the HVS activity in aged rats, which could be due to age-related suppression of the 5-HT2 receptor functions. Copyright 1998 Elsevier Science B.V.

Direct block of native and cloned (Kir2.1) inward rectifier K+ channels by chloroethylclonidine

PubMed Central

Barrett-Jolley, R; Dart, C; Standen, N B

1999-01-01

We have investigated the inhibition of inwardly rectifying potassium channels by the α-adrenergic agonist/antagonist chloroethylclonidine (CEC). We used two preparations; two-electrode voltage-clamp of rat isolated flexor digitorum brevis muscle and whole-cell patch-clamp of cell lines transfected with Kir2.1 (IRK1).In skeletal muscle and at a membrane potential of −50 mV, chloroethylclonidine (CEC), an agonist at α2-adrenergic receptors and an antagonist at α1x-receptors, was found to inhibit the inward rectifier current with a Ki of 30 μM.The inhibition of skeletal muscle inward rectifier current by CEC was not mimicked by clonidine, adrenaline or noradrenaline and was not sensitive to high concentrations of α1-(prazosin) or α2-(rauwolscine) antagonists.The degree of current inhibition by CEC was found to vary with the membrane potential (approximately 70% block at −50 mV c.f. ∼10% block at −190 mV). The kinetics of this voltage dependence were further investigated using recombinant inward rectifier K+ channels (Kir2.1) expressed in the MEL cell line. Using a two pulse protocol, we calculated the time constant for block to be ∼8 s at 0 mV, and the rate of unblock was described by the relationship τ=exp((Vm+149)/22) s.This block was effective when CEC was applied to either the inside or the outside of patch clamped cells, but ineffective when a polyamine binding site (aspartate 172) was mutated to asparagine.The data suggest that the clonidine-like imidazoline compound, CEC, inhibits inward rectifier K+ channels independently of α-receptors by directly blocking the channel pore, possibly at an intracellular polyamine binding site. PMID:10516659

Heterogeneous responses of human limbs to infused adrenergic agonists: a gravitational effect?

NASA Technical Reports Server (NTRS)

Pawelczyk, James A.; Levine, Benjamin D.

2002-01-01

Unlike quadrupeds, the legs of humans are regularly exposed to elevated pressures relative to the arms. We hypothesized that this "dependent hypertension" would be associated with altered adrenergic responsiveness. Isoproterenol (0.75-24 ng x 100 ml limb volume-1 x min-1) and phenylephrine (0.025-0.8 microg x 100 ml limb volume-1 x min-1) were infused incrementally in the brachial and femoral arteries of 12 normal volunteers; changes in limb blood flow were quantified by using strain-gauge plethysmography. Compared with the forearm, baseline calf vascular resistance was greater (38.8 +/- 2.5 vs. 26.9 +/- 2.0 mmHg x 100 ml x min x ml-1; P < 0.001) and maximal conductance was lower (46.1 +/- 11.9 vs. 59.4 +/- 13.4 ml x ml-1 x min-1 x mmHg-1; P < 0.03). Vascular conductance did not differ between the two limbs during isoproterenol infusions, whereas decreases in vascular conductance were greater in the calf than the forearm during phenylephrine infusions (P < 0.001). With responses normalized to maximal conductance, the half-maximal response for phenylephrine was significantly less for the calf than the forearm (P < 0.001), whereas the half-maximal response for isoproterenol did not differ between limbs. We conclude that alpha1- but not beta-adrenergic-receptor responsiveness in human limbs is nonuniform. The relatively greater response to alpha1-adrenergic-receptor stimulation in the calf may represent an adaptive mechanism that limits blood pooling and capillary filtration in the legs during standing.

Antiestrogenic activity of flavnoid phytochemicals mediated via c-Jun N-terminal protein kinase pathway. Cell-type specific regulation of estrogen receptor alpha

USDA-ARS?s Scientific Manuscript database

Flavonoid phytochemicals act as both agonists and antagonists of the human estrogen receptors (ERs). While a number of these compounds act by directly binding to the ER, certain phytochemicals, such as the flavonoid compounds chalcone and flavone, elicit antagonistic effects on estrogen signaling in...

β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo

PubMed Central

Jiang, Youde; Zhang, Qiuhua; Ye, Eun-Ah

2014-01-01

Purpose Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling. Methods Using retinas from 3-month-old β2-adrenergic receptor-deficient mice, we treated mice with our novel β1-/β2-adrenergic receptor agonist, Compound 49b, to assess the effects of adrenergic agonists acting only on β1-adrenergic receptors due to the absence of β2-adrenergic receptors. Western blotting or enzyme-linked immunosorbent assay (ELISA) analyses were performed for β1- and β2-adrenergic receptors, as well as key insulin resistance proteins, including TNF-α, SOCS3, IRS-1Ser307, and IRTyr960. Analyses were also performed on key anti- and proapoptotic proteins: Akt, Bcl-xL, Bax, and caspase 3. Electroretinogram analyses were conducted to assess functional changes, while histological assessment was conducted for changes in retinal thickness. Results A 2-month treatment of β2-adrenergic receptor-deficient mice with daily eye drops of 1 mM Compound 49b, a novel β1- and β2-adrenergic receptor agonist, reversed the changes in insulin resistance markers (TNF-α and SOCS3) observed in untreated β2-adrenergic receptor-deficient mice, and concomitantly increased morphological integrity (retinal thickness) and functional responses (electroretinogram amplitude). These results suggest that stimulating β1-adrenergic receptors on retinal endothelial cells or Müller cells can compensate for the loss of β2-adrenergic receptor signaling on Müller cells, restore insulin signal transduction, reduce retinal apoptosis, and enhance retinal function. Conclusions Since our previous studies with β1-adrenergic receptor knockout mice confirmed that the reverse also occurs (β2-adrenergic receptor stimulation can compensate for the loss of β1-adrenergic receptor activity), it appears that increased activity in either of these pathways alone is sufficient to block insulin resistance–based retinal cell apoptosis. PMID:24966659

Phosphorylation and desensitization of alpha1d-adrenergic receptors.

PubMed Central

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

2001-01-01

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

Anticonvulsant activity of a mGlu(4alpha) receptor selective agonist, (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid.

PubMed

Chapman, A G; Talebi, A; Yip, P K; Meldrum, B S

2001-07-20

The metabotropic Group III agonist, (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid (ACPT-1), selective for the mGlu(4alpha) receptor, suppresses sound-induced seizures in DBA/2 mice following its intracerebroventricular (i.c.v.) administration (ED(50) 5.6 [2.9-10.7], nmol i.c.v., 15 min, clonic phase) and in genetically epilepsy-prone (GEP) rats following focal administration into the inferior colliculus (ED(50) 0.08 [0.01-0.50], nmol, 60 min, clonic phase). ACPT-1 also protects against clonic seizures induced in DBA/2 mice by the Group I agonist, (RS)-3,5-dihydroxyphenylglycine (3,5-DHPG) (ED(50) 0.60 [0.29-1.2], nmol i.c.v.) and by the Group III antagonist, (RS)-alpha-methylserine-O-phosphate (MSOP) (ED(50) 49.3 [37.9-64.1], nmol i.c.v.). Another Group III agonist, (RS)-4-phosphonophenyl-glycine (PPG), preferentially activating the mGlu(8) receptor, previously shown to protect against sound-induced seizures in DBA/2 mice and GEP rats, also protects against seizures induced in DBA/2 by 3,5-DHPG (ED(50) 3.7 [2.4-5.7], nmol i.c.v.) and by the Group III antagonist, MSOP (ED(50) 40.2 [21.0-77.0], nmol i.c.v.). At very high doses (500 nmol i.c.v. and above), Group III antagonists have pro-convulsant and convulsant activity. The anticonvulsant protection against sound-induced seizures in DBA/2 mice provided by a fully protective dose (20 nmol, i.c.v.) of the mGlu(4) receptor agonist ACPT-1, is partially reversed by the co-administration of the Group III antagonists, MSOP, (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG) or (S)-2-amino-2-methyl-4-phosphonobutanoic acid (MAP4), in the 20-50 nmol dose range. At doses of 50-200 nmol, MPPG and MAP4 cause further reversal of the ACPT-1 anticonvulsant protection, while the MSOP effect on ACPT-1 protection is abolished at higher doses. In contrast, the anticonvulsant protection against sound-induced seizures in DBA/2 mice provided by a fully protective dose (20 nmol, i.c.v.) of the mGlu(8) receptor agonist PPG, is not significantly affected by the co-administration of the same Group III antagonists, MSOP, MPPG or MAP4. We conclude that activation of either mGlu(4alpha) or mGlu(8) receptors confer anticonvulsant protection in DBA/2 mice. Furthermore, the metabotropic Group III receptor antagonists, MSOP, MPPG, and MAP4 appear to be functionally selective for the mGlu(4) receptor in this system.

Guinea pig hepatocyte alpha 1A-adrenoceptors: characterization, signal transduction and regulation.

PubMed

García-Sáinz, J A; Romero-Avila, T; Olivares-Reyes, J A; Macías-Silva, M

1992-11-02

Activation of guinea pig hepatocyte alpha 1-adrenoceptors increases phosphatidylinositol (PI) labeling, [3H]inositol phosphate production and phosphorylase activity. These adrenergic actions were not altered by pretreatment with chlorethylclonidine but were blocked by 5-methyl urapidil and prazosin (the former being 3- to 10-fold more potent than the latter), indicating that alpha 1A-adrenoceptors were involved. When the cells were incubated in buffer without calcium and containing EGTA, the alpha 1A-adrenergic stimulation of PI labeling was diminished but not abolished and that of phosphorylase was not affected. The alpha 1A-adrenergic effects were insensitive to pertussis toxin treatment. Phorbol myristate acetate inhibited the alpha 1A-adrenergic actions, although at relatively large concentrations, and also those of other agents such as angiotensin II and NaF. Our data clearly indicate that guinea pig hepatocytes express alpha 1A-adrenoceptors whose activation stimulates phosphoinositide turnover, via a pertussis toxin-insensitive process; the alpha 1A-adrenergic effects were at least partially independent of extracellular calcium.

Race and sex differences in cardiovascular α-adrenergic and β-adrenergic receptor responsiveness in men and women with high blood pressure

PubMed Central

Sherwood, Andrew; Hill, LaBarron K.; Blumenthal, James A.; Johnson, Kristy S.; Hinderliter, Alan L.

2018-01-01

Objective Hypertension is associated with unfavorable changes in adrenergic receptor responsiveness, but the relationship of race and sex to adrenergic receptor responsiveness in the development of cardiovascular disease is unclear. This study examined α-adrenergic and β-adrenergic receptor responsiveness in African-American and white men and women with untreated high blood pressure (BP) (HBP) and with normal BP. Methods and results The study sample comprised 161 African-American and white men and women in the age range 25–45 years. Isoproterenol, a nonselective β-adrenergic receptor agonist, was administered intravenously to determine the bolus dose required to increase heart rate by 25 bpm, an index of β-adrenergic receptor responsiveness. Similarly, phenylephrine, an α1-adrenergic receptor agonist, was administered to determine the bolus dose required to increase BP by 25 mmHg, an index of vascular α1-adrenergic receptor responsiveness. HBP (P <0.01), male sex (P =0.04), and higher BMI (P <0.01) were all associated with reduced β-adrenergic receptor responsiveness, with a similar trend observed for African-American race (P =0.07). Conversely, α1-adrenergic receptor responsiveness was increased in association with HBP (P <0.01), female sex (P <0.01), and African-American race (P <0.01). Conclusion In the early stages of hypertension, cardiovascular β-adrenergic receptors demonstrate blunted responsiveness, whereas conversely α1-adrenergic receptors exhibit increased responsiveness. This pattern of receptor changes is especially evident in men and African-Americans, is exacerbated by obesity, and may contribute to the development of cardiovascular disease. PMID:28306633

Smoking-associated lung cancer prevention by blockade of the beta-adrenergic receptor-mediated insulin-like growth factor receptor activation.

PubMed

Min, Hye-Young; Boo, Hye-Jin; Lee, Ho Jin; Jang, Hyun-Ji; Yun, Hye Jeong; Hwang, Su Jung; Smith, John Kendal; Lee, Hyo-Jong; Lee, Ho-Young

2016-10-25

Activation of receptor tyrosine kinases (RTKs) is associated with carcinogenesis, but its contribution to smoking-associated lung carcinogenesis is poorly understood. Here we show that a tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced insulin-like growth factor 1 receptor (IGF-1R) activation via β-adrenergic receptor (β-AR) is crucial for smoking-associated lung carcinogenesis. Treatment with NNK stimulated the IGF-1R signaling pathway in a time- and dose-dependent manner, which was suppressed by pharmacological or genomic blockade of β-AR and the downstream signaling including a Gβγ subunit of β-AR and phospholipase C (PLC). Consistently, β-AR agonists led to increased IGF-1R phosphorylation. The increase in IGF2 transcription via β-AR, signal transducer and activator of transcription 3 (STAT3), and nuclear factor-kappa B (NF-κB) was associated with NNK-induced IGF-1R activation. Finally, treatment with β-AR antagonists suppressed the acquisition of transformed phenotypes in lung epithelial cells and lung tumor formation in mice. These results suggest that blocking β-AR-mediated IGF-1R activation can be an effective strategy for lung cancer prevention in smokers.

A Combination of Dexmedetomidine and Lidocaine Is a Cardiovascularly Safe Dental Local Anesthetic for Hypertensive Rats Treated With a Nonselective β-Adrenergic Antagonist.

PubMed

Tsutsui, Yukako; Sunada, Katsuhisa

2017-01-01

Hypertensive patients receiving nonselective β-adrenergic antagonists are vulnerable to hypertension and bradycardia when injected with dental local anesthetic formulations containing epinephrine. Dexmedetomidine (DEX), an α 2 -adrenergic agonist, has been reported to prolong and enhance the local anesthetic effects of lidocaine. The cardiovascular effects of the DEX-lidocaine combination have not yet been investigated in the presence of nonselective β-adrenergic antagonists. Therefore, we assessed the cardiovascular effects of the DEX-lidocaine combination in spontaneously hypertensive rats (SHR) treated with a nonselective β-adrenergic antagonist (propranolol). We injected propranolol-treated rats with various concentrations of DEX alone, 100 μg/kg epinephrine alone, or 5 μg/kg DEX combined with 2% lidocaine and measured their blood pressure (BP) and heart rates (HR) to assess the cardiovascular effects. The BP of propranolol-treated SHR was significantly increased by treatment with 100 μg/kg epinephrine alone. The BP and HR of propranolol-treated SHR were not significantly changed by treatment with low concentrations of DEX, but they were significantly decreased by treatment with a high concentration of DEX (50 μg/kg). Moreover, there was no significant difference in the BP and HR of propranolol-treated SHR after the injection of a combination of 5 μg/kg DEX and 2% lidocaine. Thus, the DEX-lidocaine combination may be an acceptable addition to dental local anesthetic solutions from a cardiovascular standpoint for hypertensive patients receiving nonselective β-adrenergic antagonists.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhtar, R.A.; Abdel-Latif, A.A.

Muscarinic cholinergic and ..cap alpha../sub 1/-adrenergic agonists provoke hydrolysis of PIP/sub 2/ into diacylglycerol (DG) and inositol trisphosphate (IP/sub 3/) in a wide variety of tissue. Recently, IP/sub 3/ has been shown to mobilize Ca/sup 2 +/ from ER in several permeabilized tissue preparations. Although rabbit cornea is enriched in ACh and NE, the physiological function of these neurotransmitters is unclear. The present studies were initiated to determine the effects of cholinergic and adrenergic agonists on PIP/sub 2/ turnover in the cornea. Addition of ACh or NE (50 ..mu..M each) to the /sup 32/P-labeled corneas for 10 min decreased themore » radioactivity in PIP/sub 2/ by 33 and 36%, and increased the radioactivity in phosphatidic acid by 72 and 52%, respectively. When the corneas were labeled with myo-(/sup 3/H)inositol, ACh and NE increased the accumulation of IP/sub 3/ by 92 and 48%, respectively. The effects of ACh and NE on phospholipid labeling and IP/sub 3/ accumulation were specifically inhibited by atropine (10 ..mu..M) and prazosin (10 ..mu..M), respectively. The data suggest the presence of muscarinic cholinergic and ..cap alpha../sub 1/-adrenergic receptors in the rabbit cornea. Furthermore, activation of these receptors leads to cleavage of PIP/sub 2/ into DG and IP/sub 3/ which may function as second messengers in this tissue.« less

Mechanisms of postspaceflight orthostatic hypotension: low alpha1-adrenergic receptor responses before flight and central autonomic dysregulation postflight

NASA Technical Reports Server (NTRS)

Meck, Janice V.; Waters, Wendy W.; Ziegler, Michael G.; deBlock, Heidi F.; Mills, Paul J.; Robertson, David; Huang, Paul L.

2004-01-01

Although all astronauts experience symptoms of orthostatic intolerance after short-duration spaceflight, only approximately 20% actually experience presyncope during upright posture on landing day. The presyncopal group is characterized by low vascular resistance before and after flight and low norepinephrine release during orthostatic stress on landing day. Our purpose was to determine the mechanisms of the differences between presyncopal and nonpresyncopal groups. We studied 23 astronauts 10 days before launch, on landing day, and 3 days after landing. We measured pressor responses to phenylephrine injections; norepinephrine release with tyramine injections; plasma volumes; resting plasma levels of chromogranin A (a marker of sympathetic nerve terminal release), endothelin, dihydroxyphenylglycol (DHPG, an intracellular metabolite of norepinephrine); and lymphocyte beta(2)-adrenergic receptors. We then measured hemodynamic and neurohumoral responses to upright tilt. Astronauts were separated into two groups according to their ability to complete 10 min of upright tilt on landing day. Compared with astronauts who were not presyncopal on landing day, presyncopal astronauts had 1). significantly smaller pressor responses to phenylephrine both before and after flight; 2). significantly smaller baseline norepinephrine, but significantly greater DHPG levels, on landing day; 3). significantly greater norepinephrine release with tyramine on landing day; and 4). significantly smaller norepinephrine release, but significantly greater epinephrine and arginine vasopressin release, with upright tilt on landing day. These data suggest that the etiology of orthostatic hypotension and presyncope after spaceflight includes low alpha(1)-adrenergic receptor responsiveness before flight and a remodeling of the central nervous system during spaceflight such that sympathetic responses to baroreceptor input become impaired.

Mechanisms of postspaceflight orthostatic hypotension: low alpha1-adrenergic receptor responses before flight and central autonomic dysregulation postflight.

PubMed

Meck, Janice V; Waters, Wendy W; Ziegler, Michael G; deBlock, Heidi F; Mills, Paul J; Robertson, David; Huang, Paul L

2004-04-01

Although all astronauts experience symptoms of orthostatic intolerance after short-duration spaceflight, only approximately 20% actually experience presyncope during upright posture on landing day. The presyncopal group is characterized by low vascular resistance before and after flight and low norepinephrine release during orthostatic stress on landing day. Our purpose was to determine the mechanisms of the differences between presyncopal and nonpresyncopal groups. We studied 23 astronauts 10 days before launch, on landing day, and 3 days after landing. We measured pressor responses to phenylephrine injections; norepinephrine release with tyramine injections; plasma volumes; resting plasma levels of chromogranin A (a marker of sympathetic nerve terminal release), endothelin, dihydroxyphenylglycol (DHPG, an intracellular metabolite of norepinephrine); and lymphocyte beta(2)-adrenergic receptors. We then measured hemodynamic and neurohumoral responses to upright tilt. Astronauts were separated into two groups according to their ability to complete 10 min of upright tilt on landing day. Compared with astronauts who were not presyncopal on landing day, presyncopal astronauts had 1). significantly smaller pressor responses to phenylephrine both before and after flight; 2). significantly smaller baseline norepinephrine, but significantly greater DHPG levels, on landing day; 3). significantly greater norepinephrine release with tyramine on landing day; and 4). significantly smaller norepinephrine release, but significantly greater epinephrine and arginine vasopressin release, with upright tilt on landing day. These data suggest that the etiology of orthostatic hypotension and presyncope after spaceflight includes low alpha(1)-adrenergic receptor responsiveness before flight and a remodeling of the central nervous system during spaceflight such that sympathetic responses to baroreceptor input become impaired.

The second Lilly Prize Lecture, University of Newcastle, July 1977. beta-Adrenergic receptor blockade in hypertension, past, present and future.

PubMed Central

Prichard, B N

1978-01-01

All beta-adrenoceptor blocking drugs that have been described share the common property of being competitive inhibitors. They differ in their associated properties, the presence or absence of cardioselectivity, membrane stabilizing activity, and partial agonist activity. Recently some beta-adrenoceptor blocking drugs have been reported which also possess alpha-adrenoceptor blocking activity. The associated properties have been used as a basis for classifying beta-adrenoceptor blocking drugs (Fitzgerald, 1969, 1972). The presence or absence of cardioselectivity is most useful for dividing beta-adrenoceptor blocking drugs. The non-selective drugs (Division I) can be further divided according to the presence or absence of intrinsic sympathomimetic activity (ISA) and membrane stabilizing activity (Fitzgerald's groups I-IV). Group I possess both membrane activity and ISA, e.g. alprenolol, oxprenolol, group II just membrane action, e.g. propanolol, group III ISA but no membrane action, e.g. pindolol. Fitzgerald placed pindolol in group I but should be placed in group III as it possesses a high degree of beta-adrenoceptor blocking potency in relation to its membrane activity (Prichard, 1974). Finally drugs in group IV have neither ISA nor membrane action, e.g. sotalol, timolol. The cardioselective drugs (Division II) can be similarly sub-divided into groups I-IV according to the presence or absence of ISA or membrane action (Fitzgerald grouped all these together as group V). Lastly there are new beta-adrenergic receptor blocking drugs which in addition have alpha- adrenergic receptor blocking properties (Division III). PMID:26370

Caged Naloxone Reveals Opioid Signaling Deactivation Kinetics

PubMed Central

Banghart, Matthew R.; Shah, Ruchir C.; Lavis, Luke D.

2013-01-01

The spatiotemporal dynamics of opioid signaling in the brain remain poorly defined. Photoactivatable opioid ligands provide a means to quantitatively measure these dynamics and their underlying mechanisms in brain tissue. Although activation kinetics can be assessed using caged agonists, deactivation kinetics are obscured by slow clearance of agonist in tissue. To reveal deactivation kinetics of opioid signaling we developed a caged competitive antagonist that can be quickly photoreleased in sufficient concentrations to render agonist dissociation effectively irreversible. Carboxynitroveratryl-naloxone (CNV-NLX), a caged analog of the competitive opioid antagonist NLX, was readily synthesized from commercially available NLX in good yield and found to be devoid of antagonist activity at heterologously expressed opioid receptors. Photolysis in slices of rat locus coeruleus produced a rapid inhibition of the ionic currents evoked by multiple agonists of the μ-opioid receptor (MOR), but not of α-adrenergic receptors, which activate the same pool of ion channels. Using the high-affinity peptide agonist dermorphin, we established conditions under which light-driven deactivation rates are independent of agonist concentration and thus intrinsic to the agonist-receptor complex. Under these conditions, some MOR agonists yielded deactivation rates that are limited by G protein signaling, whereas others appeared limited by agonist dissociation. Therefore, the choice of agonist determines which feature of receptor signaling is unmasked by CNV-NLX photolysis. PMID:23960100

Neuroleptics and learning: effects of haloperidol, molindone, mesoridazine and thioridazine on the behavior of pigeons under a repeated acquisition procedure.

PubMed

Poling, A; Cleary, J; Berens, K; Thompson, T

1990-12-01

The purpose of the present study was to examine the effects of haloperidol (0.3-10 mg/kg), molindone (0.3-5.6 mg/kg), mesoridazine (0.3-10) and thioridazine (0.3-25 mg/kg) on the behavior of pigeons exposed to a repeated acquisition procedure. At sufficiently high doses, each of these neuroleptics increased error rates (interfered with learning) and reduced rate of responding. When the drugs were compared on the basis of absolute doses administered, haloperidol disrupted behavior at doses considerably lower than the other drugs. If, however, chlorpromazine equivalent doses were examined, haloperidol was the least disruptive of the four drugs. Comparing the degree of behavioral disruption produced by the four drugs with their relative neuroreceptor affinities for dopamine D-2, cholinergic muscarinic, histamine H1, alpha-1 adrenergic and alpha-2 adrenergic receptors suggests that behavioral disruption cannot be attributed in any simple way to dopamine or acetylcholine receptor blockade. The relationship between the behavioral effects of neuroleptics and their simple neuropharmacological actions must be considered as highly tentative.

Lamina-associated polypeptide 2alpha loss impairs heart function and stress response in mice.

PubMed

Gotic, Ivana; Leschnik, Michael; Kolm, Ursula; Markovic, Mato; Haubner, Bernhard J; Biadasiewicz, Katarzyna; Metzler, Bernhard; Stewart, Colin L; Foisner, Roland

2010-02-05

Lamina-associated polypeptide (LAP)2alpha is a mammalian chromatin-binding protein that interacts with a fraction of A-type lamins in the nuclear interior. Because mutations in lamins and LAP2alpha lead to cardiac disorders in humans, we hypothesized that these factors may play important roles in heart development and adult tissue homeostasis. We asked whether the presence of LAP2alpha was required for normal cardiac function. To study the molecular mechanisms of the disease, we analyzed heart structure and function in complete and conditional Lap2alpha(-/-) mice as well as Lap2alpha(-/-)/Mdx mutants. Unlike conditional deletion of LAP2alpha in late embryonic striated muscle, its complete knockout caused systolic dysfunction in young mice, accompanied by sporadic fibrosis in old animals, as well as deregulation of major cardiac transcription factors GATA4 and myocyte enhancer factor 2c. Activation of compensatory pathways, including downregulation of beta-adrenergic receptor signaling, resulted in reduced responsiveness of the myocardium to chronic beta-adrenergic stimulation and stalled the progression of LAP2alpha-deficient hearts from hypertrophy toward cardiac failure. Dystrophin deficiency in an Mdx background resulted in a transient rescue of the Lap2alpha(-/-) phenotype. Our data suggest a novel role of LAP2alpha in the maintenance of cardiac function under normal and stress conditions.

Race and sex differences in cardiovascular α-adrenergic and β-adrenergic receptor responsiveness in men and women with high blood pressure.

PubMed

Sherwood, Andrew; Hill, LaBarron K; Blumenthal, James A; Johnson, Kristy S; Hinderliter, Alan L

2017-05-01

Hypertension is associated with unfavorable changes in adrenergic receptor responsiveness, but the relationship of race and sex to adrenergic receptor responsiveness in the development of cardiovascular disease is unclear. This study examined α-adrenergic and ß-adrenergic receptor responsiveness in African-American and white men and women with untreated high blood pressure (BP) (HBP) and with normal BP. The study sample comprised 161 African-American and white men and women in the age range 25-45 years. Isoproterenol, a nonselective ß-adrenergic receptor agonist, was administered intravenously to determine the bolus dose required to increase heart rate by 25 bpm, an index of β-adrenergic receptor responsiveness. Similarly, phenylephrine, an α1-adrenergic receptor agonist, was administered to determine the bolus dose required to increase BP by 25 mmHg, an index of vascular α1-adrenergic receptor responsiveness. HBP (P < 0.01), male sex (P = 0.04), and higher BMI (P < 0.01) were all associated with reduced β-adrenergic receptor responsiveness, with a similar trend observed for African-American race (P = 0.07). Conversely, α1-adrenergic receptor responsiveness was increased in association with HBP (P < 0.01), female sex (P < 0.01), and African-American race (P < 0.01). In the early stages of hypertension, cardiovascular β-adrenergic receptors demonstrate blunted responsiveness, whereas conversely α1-adrenergic receptors exhibit increased responsiveness. This pattern of receptor changes is especially evident in men and African-Americans, is exacerbated by obesity, and may contribute to the development of cardiovascular disease.

The role of adrenergic activation on murine luteal cell viability and progesterone production.

PubMed

Wang, Jing; Tang, Min; Jiang, Huaide; Wu, Bing; Cai, Wei; Hu, Chuan; Bao, Riqiang; Dong, Qiming; Xiao, Li; Li, Gang; Zhang, Chunping

2016-09-15

Sympathetic innervations exist in mammalian CL. The action of catecholaminergic system on luteal cells has been the focus of a variety of studies. Norepinephrine (NE) increased progesterone secretion of cattle luteal cells by activating β-adrenoceptors. In this study, murine luteal cells were treated with NE and isoprenaline (ISO). We found that NE increased the viability of murine luteal cells and ISO decreased the viability of luteal cells. Both NE and ISO promoted the progesterone production. Nonselective β-adrenergic antagonist, propranolol reversed the effect of ISO on cell viability but did not reverse the effect of NE on cell viability. Propranolol blocked the influence of NE and ISO on progesterone production. These results reveal that the increase of luteal cell viability induced by NE is not dependent on β-adrenergic activation. α-Adrenergic activation possibly contributes to it. Both NE and ISO increased progesterone production through activating β-adrenergic receptor. Further study showed that CyclinD2 is involved in the increase of luteal cell induced by NE. 3β-Hydroxysteroid dehydrogenase, LHR, steroidogenic acute regulatory protein (StAR), and PGF2α contribute to the progesterone production induced by NE and ISO. Copyright © 2016 Elsevier Inc. All rights reserved.

Stevia Nonsweetener Fraction Displays an Insulinotropic Effect Involving Neurotransmission in Pancreatic Islets.

PubMed

Piovan, Silvano; Pavanello, Audrei; Peixoto, Giuliana Maria Ledesma; Matiusso, Camila Cristina Ianoni; de Moraes, Ana Maria Praxedes; Martins, Isabela Peixoto; Malta, Ananda; Palma-Rigo, Kesia; da Silva Franco, Claudinéia Conationi; Milani, Paula Gimenez; Dacome, Antonio Sérgio; da Costa, Silvio Claudio; de Freitas Mathias, Paulo Cezar; Mareze-Costa, Cecília Edna

2018-01-01

Stevia rebaudiana (Bert.) Bertoni besides being a source of noncaloric sweeteners is also an important source of bioactive molecules. Many plant extracts, mostly obtained with ethyl acetate solvent, are rich in polyphenol compounds that present insulinotropic effects. To investigate whether the nonsweetener fraction, which is rich in phenolic compounds isolated from Stevia rebaudiana with the solvent ethyl acetate (EAF), has an insulinotropic effect, including interference at the terminals of the autonomic nervous system of the pancreatic islets of rats. Pancreatic islets were isolated from Wistar rats and incubated with EAF and inhibitory or stimulatory substances of insulin secretion, including cholinergic and adrenergic agonists and antagonists. EAF potentiates glucose-stimulated insulin secretion (GSIS) only in the presence of high glucose and calcium-dependent concentrations. EAF increased muscarinic insulinotropic effects in pancreatic islets, interfering with the muscarinic receptor subfamily M 3 . Adrenergic inhibitory effects on GSIS were attenuated in the presence of EAF, which interfered with the adrenergic α 2 receptor. Results suggest that EAF isolated from stevia leaves is a potential therapy for treating type 2 diabetes mellitus by stimulating insulin secretion only in high glucose concentrations, enhancing parasympathetic signal transduction and inhibiting sympathetic signal transduction in beta cells.

Stevia Nonsweetener Fraction Displays an Insulinotropic Effect Involving Neurotransmission in Pancreatic Islets

PubMed Central

Pavanello, Audrei; Peixoto, Giuliana Maria Ledesma; Matiusso, Camila Cristina Ianoni; de Moraes, Ana Maria Praxedes; Martins, Isabela Peixoto; Palma-Rigo, Kesia; da Silva Franco, Claudinéia Conationi; Milani, Paula Gimenez; Dacome, Antonio Sérgio; da Costa, Silvio Claudio; de Freitas Mathias, Paulo Cezar; Mareze-Costa, Cecília Edna

2018-01-01

Stevia rebaudiana (Bert.) Bertoni besides being a source of noncaloric sweeteners is also an important source of bioactive molecules. Many plant extracts, mostly obtained with ethyl acetate solvent, are rich in polyphenol compounds that present insulinotropic effects. To investigate whether the nonsweetener fraction, which is rich in phenolic compounds isolated from Stevia rebaudiana with the solvent ethyl acetate (EAF), has an insulinotropic effect, including interference at the terminals of the autonomic nervous system of the pancreatic islets of rats. Pancreatic islets were isolated from Wistar rats and incubated with EAF and inhibitory or stimulatory substances of insulin secretion, including cholinergic and adrenergic agonists and antagonists. EAF potentiates glucose-stimulated insulin secretion (GSIS) only in the presence of high glucose and calcium-dependent concentrations. EAF increased muscarinic insulinotropic effects in pancreatic islets, interfering with the muscarinic receptor subfamily M3. Adrenergic inhibitory effects on GSIS were attenuated in the presence of EAF, which interfered with the adrenergic α 2 receptor. Results suggest that EAF isolated from stevia leaves is a potential therapy for treating type 2 diabetes mellitus by stimulating insulin secretion only in high glucose concentrations, enhancing parasympathetic signal transduction and inhibiting sympathetic signal transduction in beta cells. PMID:29853880

Nicotine induces fibrogenic changes in human liver via nicotinic acetylcholine receptors expressed on hepatic stellate cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soeda, Junpei; Morgan, Maelle; McKee, Chad

Highlights: Black-Right-Pointing-Pointer Cigarette smoke may induce liver fibrosis via nicotine receptors. Black-Right-Pointing-Pointer Nicotine induces proliferation of hepatic stellate cells (HSCs). Black-Right-Pointing-Pointer Nicotine activates hepatic fibrogenic pathways. Black-Right-Pointing-Pointer Nicotine receptor antagonists attenuate HSC proliferation. Black-Right-Pointing-Pointer Nicotinic receptor antagonists may have utility as novel anti-fibrotic agents. -- Abstract: Background and aims: Cigarette smoke (CS) may cause liver fibrosis but possible involved mechanisms are unclear. Among the many chemicals in CS is nicotine - which affects cells through nicotinic acetylcholine receptors (nAChR). We studied the effects of nicotine, and involved pathways, on human primary hepatic stellate cells (hHSCs), the principal fibrogenic cells inmore » the liver. We then determined possible disease relevance by assaying nAChR in liver samples from human non-alcoholic steatohepatitis (NASH). Methods: hHSC were isolated from healthy human livers and nAChR expression analyzed - RT-PCR and Western blotting. Nicotine induction of hHSC proliferation, upregulation of collagen1-{alpha}2 and the pro-fibrogenic cytokine transforming growth factor beta 1 (TGF-{beta}1) was determined along with involved intracellular signaling pathways. nAChR mRNA expression was finally analyzed in whole liver biopsies obtained from patients diagnosed with non-alcoholic steatohepatitis (NASH). Results: hHSCs express muscle type ({alpha}1, {beta}1, delta and epsilon) and neuronal type ({alpha}3, {alpha}6, {alpha}7, {beta}2 and {beta}4) nAChR subunits at the mRNA level. Among these subunits, {alpha}3, {alpha}7, {beta}1 and {epsilon} were predominantly expressed as confirmed by Western blotting. Nicotine induced hHSC proliferation was attenuated by mecamylamine (p < 0.05). Additionally, collagen1-{alpha}2 and TGF-{beta}1 mRNA expression were significantly upregulated by nicotine and inhibited by mecamylamine. {alpha}1 and {alpha}3-nAChR mRNA expression was significantly upregulated in NASH fibrosis compared to normal livers. Conclusion: Nicotine at levels in smokers' blood is pro-fibrogenic, through actions on hHSCs expressed nAChRs. Therefore, CS, via its nicotine content, may worsen liver fibrosis. Moreover, nicotinic receptor antagonists may have utility as novel anti-fibrotic agents.« less

Adrenergic receptor-mediated modulation of striatal firing patterns.

PubMed

Ohta, Hiroyuki; Kohno, Yu; Arake, Masashi; Tamura, Risa; Yukawa, Suguru; Sato, Yoshiaki; Morimoto, Yuji; Nishida, Yasuhiro; Yawo, Hiromu

2016-11-01

Although noradrenaline and adrenaline are some of the most important neurotransmitters in the central nervous system, the effects of noradrenergic/adrenergic modulation on the striatum have not been determined. In order to explore the effects of adrenergic receptor (AR) agonists on the striatal firing patterns, we used optogenetic methods which can induce continuous firings. We employed transgenic rats expressing channelrhodopsin-2 (ChR2) in neurons. The medium spiny neuron showed a slow rising depolarization during the 1-s long optogenetic striatal photostimulation and a residual potential with 8.6-s half-life decay after the photostimulation. As a result of the residual potential, five repetitive 1-sec long photostimulations with 20-s onset intervals cumulatively increased the number of spikes. This 'firing increment', possibly relating to the timing control function of the striatum, was used to evaluate the AR modulation. The β-AR agonist isoproterenol decreased the firing increment between the 1st and 5th stimulation cycles, while the α 1 -AR agonist phenylephrine enhanced the firing increment. Isoproterenol and adrenaline increased the early phase (0-0.5s of the photostimulation) firing response. This adrenergic modulation was inhibited by the β-antagonist propranolol. Conversely, phenylephrine and noradrenaline reduced the early phase response. β-ARs and α 1 -ARs work in opposition controlling the striatal firing initiation and the firing increment. Copyright © 2016 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

A deletion in the alpha2B-adrenergic receptor gene and autonomic nervous function in central obesity.

PubMed

Sivenius, Katariina; Niskanen, Leo; Laakso, Markku; Uusitupa, Matti

2003-08-01

We investigated the impact of a three-amino acid deletion (12Glu9) polymorphism in the alpha(2B)-adrenergic receptor gene on autonomic nervous function. The short form (Glu(9)/Glu(9)) of the polymorphism has previously been associated with a reduced basal metabolic rate in obese subjects. Because autonomic nervous function participates in the regulation of energy metabolism, there could be a link between this polymorphism and autonomic nervous function. Data of a 10-year follow-up study with 126 nondiabetic control subjects and 84 type 2 diabetic patients were used to determine the effects of the 12Glu9 polymorphism on autonomic nervous function. A deep breathing test and an orthostatic test were used to investigate parasympathetic and sympathetic autonomic nervous function. In addition, cardiovascular autonomic function was studied using power spectral analysis of heart rate variability. No significant differences were found in the frequency of the 12Glu9 deletion polymorphism between nondiabetic and diabetic subjects. The nondiabetic men with the Glu(9)/Glu(9) genotype, especially those with abdominal obesity, had significantly lower total and low-frequency power values in the power spectral analysis when compared with other men. Furthermore, in a longitudinal analysis of 10 years, the decrease in parasympathetic function was greater in nondiabetic men with the Glu(9)/Glu(9) genotype than in the men with the Glu(9)/Glu(12) or Glu(12)/Glu(12) genotypes. The results of the present study suggest that the 12Glu9 polymorphism of the alpha(2B)-adrenergic receptor gene modulates autonomic nervous function in Finnish nondiabetic men. In the nondiabetic men with the Glu(9)/Glu(9) genotype, the general autonomic tone is depressed, and vagal activity especially becomes impaired with time. Furthermore, this association is accentuated by central obesity.

Competitive antagonism of recombinant P2X(2/3) receptors by 2', 3'-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate (TNP-ATP).

PubMed

Burgard, E C; Niforatos, W; van Biesen, T; Lynch, K J; Kage, K L; Touma, E; Kowaluk, E A; Jarvis, M F

2000-12-01

TNP-ATP has become widely recognized as a potent and selective P2X receptor antagonist, and is currently being used to discriminate between subtypes of P2X receptors in a variety of tissues. We have investigated the ability of TNP-ATP to inhibit alpha,beta-methylene ATP (alpha,beta-meATP)-evoked responses in 1321N1 human astrocytoma cells expressing recombinant rat or human P2X(2/3) receptors. Pharmacological responses were measured using electrophysiological and calcium imaging techniques. TNP-ATP was a potent inhibitor of P2X(2/3) receptors, blocking both rat and human receptors with IC(50) values of 3 to 6 nM. In competition studies, 10 to 1000 microM alpha,beta-meATP was able to overcome TNP-ATP inhibition. Schild analysis revealed that TNP-ATP was a competitive antagonist with pA(2) values of -8.7 and -8.2. Inhibition of P2X(2/3) receptors by TNP-ATP was rapid in onset, reversible, and did not display use dependence. Although the onset kinetics of inhibition were concentration-dependent, the TNP-ATP off-kinetics were concentration-independent and relatively slow. Full recovery from TNP-ATP inhibition did not occur until >/=5 s after removal of the antagonist. Because of the slow off-kinetics of TNP-ATP, full competition with alpha,beta-meATP for receptor occupancy could be seen only after both ligands had reached a steady-state condition. It is proposed that the slowly desensitizing P2X(2/3) receptor allowed this competitive interaction to be observed over time, whereas the rapid desensitization of other P2X receptors (P2X(3)) may mask the detection of competitive inhibition by TNP-ATP.

Nicergoline, a drug used for age-dependent cognitive impairment, protects cultured neurons against beta-amyloid toxicity.

PubMed

Caraci, Filippo; Chisari, Mariangela; Frasca, Giuseppina; Canonico, Pier Luigi; Battaglia, Angelo; Calafiore, Marco; Battaglia, Giuseppe; Bosco, Paolo; Nicoletti, Ferdinando; Copani, Agata; Sortino, Maria Angela

2005-06-14

Nicergoline, a drug used for the treatment of Alzheimer's disease and other types of dementia, was tested for its ability to protect neurons against beta-amyloid toxicity. Pure cultures of rat cortical neurons were challenged with a toxic fragment of beta-amyloid peptide (betaAP(25-35)) and toxicity was assessed after 24 h. Micromolar concentrations of nicergoline or its metabolite, MDL, attenuated betaAP(25-35)-induced neuronal death, whereas MMDL (another metabolite of nicergoline), the alpha1-adrenergic receptor antagonist, prazosin, or the serotonin 5HT-2 receptor antagonist, methysergide, were inactive. Nicergoline increased the basal levels of Bcl-2 and reduced the increase in Bax levels induced by beta-amyloid, indicating that the drug inhibits the execution of an apoptotic program in cortical neurons. In mixed cultures of rat cortical cells containing both neurons and astrocytes, nicergoline and MDL were more efficacious than in pure neuronal cultures in reducing beta-amyloid neurotoxicity. Experiments carried out in pure cultures of astrocytes showed that a component of neuroprotection was mediated by a mechanism of glial-neuronal interaction. The conditioned medium of cultured astrocytes treated with nicergoline or MDL for 72-96 h (collected 24 h after drug withdrawal) was neuroprotective when transferred to pure neuronal cultures challenged with beta-amyloid. In cultured astrocytes, nicergoline increased the intracellular levels of transforming-growth factor-beta and glial-derived neurotrophic factor, two trophic factors that are known to protect neurons against beta-amyloid toxicity. These results raise the possibility that nicergoline reduces neurodegeneration in the Alzheimer's brain.

Design and synthesis of novel sulfonamide-containing bradykinin hB2 receptor antagonists. 1. Synthesis and SAR of alpha,alpha-dimethylglycine sulfonamides.

PubMed

Fattori, Daniela; Rossi, Cristina; Fincham, Christopher I; Berettoni, Marco; Calvani, Federico; Catrambone, Fernando; Felicetti, Patrizia; Gensini, Martina; Terracciano, Rosa; Altamura, Maria; Bressan, Alessandro; Giuliani, Sandro; Maggi, Carlo A; Meini, Stefania; Valenti, Claudio; Quartara, Laura

2006-06-15

We recently published the extensive in vivo pharmacological characterization of MEN 16132 (J. Pharmacol. Exp. Ther. 2005, 616-623; Eur. J. Pharmacol. 2005, 528, 7), a member of the sulfonamide-containing human B(2) receptor (hB(2)R) antagonists. Here we report, in detail, how this family of compounds was designed, synthesized, and optimized to provide a group of products with subnanomolar affinity for the hB(2)R and high in vivo potency after topical administration to the respiratory tract. The series was designed on the basis of indications from the X-ray structures of the key structural motifs A and B present in known antagonists and is characterized by the presence of an alpha,alpha-dialkyl amino acid. The first lead (17) of the series was submitted to extensive chemical work to elucidate the structural requirements to increase hB(2) receptor affinity and antagonist potency in bioassays expressing the human B(2) receptor (hB(2)R). The following structural features were selected: a 2,4-dimethylquinoline moiety and a piperazine linker acylated with a basic amino acid. The representative lead compound 68 inhibited the specific binding of [(3)H]BK to hB(2)R with a pKi of 9.4 and antagonized the BK-induced inositolphosphate (IP) accumulation in recombinant cell systems expressing the hB(2)R with a pA(2) of 9.1. Moreover, compound 68 when administered (300 nmol/kg) intratracheally in the anesthetized guinea pig, was able to significantly inhibit BK-induced bronchoconstriction for up to 120 min after its administration, while having a lower and shorter lasting effect on hypotension.

Discovery of a novel nicotinic receptor antagonist for the treatment of nicotine addiction: 1-(3-Picolinium)-12-triethylammonium-dodecane dibromide (TMPD).

PubMed

Dwoskin, Linda P; Joyce, B Matthew; Zheng, Guangrong; Neugebauer, Nichole M; Manda, Vamshi K; Lockman, Paul; Papke, Roger L; Bardo, Michael T; Crooks, Peter A

2007-10-15

Limitations in efficacy and high relapse rates of currently available smoking cessation agents reveal the need for more efficacious pharmacotherapies. One strategy is to develop subtype-selective nicotinic receptor (nAChR) antagonists that inhibit nicotine-evoked dopamine (DA) release, the primary neurotransmitter involved in nicotine reward. Simple alkylation of the pyridino N-atom converts nicotine from a potent agonist into a potent antagonist. The classical antagonists, hexamethonium and decamethonium, differentiate between peripheral nAChR subtypes. Using a similar approach, we interconnected varying quaternary ammonium moieties with a lipophilic linker to provide N,N'-bis-nicotinium analogs, affording a lead compound, N,N'-dodecyl-1,12-diyl-bis-3-picolinium dibromide (bPiDDB), which inhibited nicotine-evoked DA release and decreased nicotine self-administration. The current work describes a novel compound, 1-(3-picolinium)-12-triethylammonium-dodecane dibromide (TMPD), a hybrid of bPiDDB and decamethonium. TMPD completely inhibited (IC(50)=500 nM) nicotine-evoked DA release from superfused rat striatal slices, suggesting that TMPD acts as a nAChR antagonist at more than one subtype. TMPD (1 microM) inhibited the response to acetylcholine at alpha3beta4, alpha4beta4, alpha4beta2, and alpha1beta1varepsilondelta receptors expressed in Xenopus oocytes. TMPD had a 2-fold higher affinity than choline for the blood-brain barrier choline transporter, suggesting brain bioavailability. TMPD did not inhibit hyperactivity in nicotine sensitized rats, but significantly and specifically decreased nicotine self-administration. Together, the results suggest that TMPD may have the ability to reduce the rewarding effect of nicotine with minimal side effects, a pharmacological profile indicative of potential clinical utility for the treatment of tobacco dependence.

Systemic and regional flow distribution in normotensive and spontaneously hypertensive young rats subjected to lifetime beta-adrenergic receptor blockade.

PubMed

Nishiyama, K; Nishiyama, A; Pfeffer, M A; Frohlich, E D

1978-01-01

To determine quantitatively organ blood flow distribution as the result of lifelong beta-adrenergic receptor blockade, 23 and 24 normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, respectively, were treated from conception with tap water (control; 10 WKY and 8 SHR), propranolol (0.5 mg/ml drinking water; 6 WKY and 8 SHR), or timolol (0.5 mg/ml drinking water; 7 WKY and 8 SHR) via placental circulation, mothers' milk, and drinking water. At 12 weeks of age all six groups were studied hemodynamically under ether anesthesia using an electromagnetic flowmeter and radioactive carbonized (15 micrometer) microspheres. Untreated SHR demonstrated normal cardiac output (CO) and CO distribution to all organs except for myocardium and testes, thereby confirming our previous work. With either propranolol or timolol treatment the course of development and maintenance of arterial pressure was no different than the pure-tap-water-fed WKY and SHR despite an approximate 30% reduction in CO. Further, with both beta-receptor antagonists CO distribution was significantly reduced to skeletal muscle (p less than 0.001), unchanged to the heart, and increased (p less than 0.05) to the remaining organs (including kidneys and brain) in both groups. Thus, as a result of lifelong beta-adrenergic receptor blockade, CO was reduced; and this was associated with a redistribution of blood flow so that flow to the kidney, brain, and splanchnic organs could be maintained at the expense of skeletal muslce perfusion.

β1-adrenergic receptors activate two distinct signaling pathways in striatal neurons

PubMed Central

Meitzen, John; Luoma, Jessie I.; Stern, Christopher M.; Mermelstein, Paul G.

2010-01-01

Monoamine action in the dorsal striatum and nucleus accumbens plays essential roles in striatal physiology. Although research often focuses on dopamine and its receptors, norepinephrine and adrenergic receptors are also crucial in regulating striatal function. While noradrenergic neurotransmission has been identified in the striatum, little is known regarding the signaling pathways activated by β-adrenergic receptors in this brain region. Using cultured striatal neurons, we characterized a novel signaling pathway by which activation of β1-adrenergic receptors leads to the rapid phosphorylation of cAMP Response Element Binding Protein (CREB), a transcription-factor implicated as a molecular switch underlying long-term changes in brain function. Norepinephrine-mediated CREB phosphorylation requires β1-adrenergic receptor stimulation of a receptor tyrosine kinase, ultimately leading to the activation of a Ras/Raf/MEK/MAPK/MSK signaling pathway. Activation of β1-adrenergic receptors also induces CRE-dependent transcription and increased c-fos expression. In addition, stimulation of β1-adrenergic receptors produces cAMP production, but surprisingly, β1-adrenergic receptor activation of adenylyl cyclase was not functionally linked to rapid CREB phosphorylation. These findings demonstrate that activation of β1-adrenergic receptors on striatal neurons can stimulate two distinct signaling pathways. These adrenergic actions can produce long-term changes in gene expression, as well as rapidly modulate cellular physiology. By elucidating the mechanisms by which norepinephrine and β1-adrenergic receptor activation affects striatal physiology, we provide the means to more fully understand the role of monoamines in modulating striatal function, specifically how norepinephrine and β1-adrenergic receptors may affect striatal physiology. PMID:21143600

β2-adrenoceptor blockage induces G1/S phase arrest and apoptosis in pancreatic cancer cells via Ras/Akt/NFκB pathway.

PubMed

Zhang, Dong; Ma, Qingyong; Wang, Zheng; Zhang, Min; Guo, Kun; Wang, Fengfei; Wu, Erxi

2011-11-26

Smoking and stress, pancreatic cancer (PanCa) risk factors, stimulate nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and catecholamines production respectively. NNK and catecholamine bind the β-adrenoceptors and induce PanCa cell proliferation; and we have previously suggested that β-adrenergic antagonists may suppress proliferation and invasion and stimulate apoptosis in PanCa. To clarify the mechanism of apoptosis induced by β2-adrenergic antagonist, we hypothesize that blockage of the β2-adrenoceptor could induce G1/S phase arrest and apoptosis and Ras may be a key player in PanCa cells. The β1 and β2-adrenoceptor proteins were detected on the cell surface of PanCa cells from pancreatic carcinoma specimen samples by immunohistochemistry. The β2-adrenergic antagonist ICI118,551 significantly induced G1/S phase arrest and apoptosis compared with the β1-adrenergic antagonist metoprolol, which was determined by the flow cytometry assay. β2-adrenergic antagonist therapy significantly suppressed the expression of extracellular signal-regulated kinase, Akt, Bcl-2, cyclin D1, and cyclin E and induced the activation of caspase-3, caspase-9 and Bax by Western blotting. Additionally, the β2-adrenergic antagonist reduced the activation of NFκB in vitro cultured PanCa cells. The blockage of β2-adrenoceptor markedly induced PanCa cells to arrest at G1/S phase and consequently resulted in cell death, which is possibly due to that the blockage of β2-adrenoceptor inhibited NFκB, extracellular signal-regulated kinase, and Akt pathways. Therefore, their upstream molecule Ras may be a key factor in the β2-adrenoceptor antagonist induced G1/S phase arrest and apoptosis in PanCa cells. The new pathway discovered in this study may provide an effective therapeutic strategy for PanCa.

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

PubMed Central

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

2015-01-01

ABSTRACT Filoviruses, consisting of Ebola virus (EBOV) and Marburg virus (MARV), are among the most lethal infectious threats to mankind. Infections by these viruses can cause severe hemorrhagic fevers in humans and nonhuman primates with high mortality rates. Since there is currently no vaccine or antiviral therapy approved for humans, there is an urgent need to develop prophylactic and therapeutic options for use during filoviral outbreaks and bioterrorist attacks. One of the ideal targets against filoviral infection and diseases is at the entry step, which is mediated by the filoviral glycoprotein (GP). In this report, we screened a chemical library of small molecules and identified numerous inhibitors, which are known G protein-coupled receptor (GPCR) antagonists targeting different GPCRs, including histamine receptors, 5-HT (serotonin) receptors, muscarinic acetylcholine receptor, and adrenergic receptor. These inhibitors can effectively block replication of both infectious EBOV and MARV, indicating a broad antiviral activity of the GPCR antagonists. The time-of-addition experiment and microscopic studies suggest that GPCR antagonists block filoviral entry at a step following the initial attachment but prior to viral/cell membrane fusion. These results strongly suggest that GPCRs play a critical role in filoviral entry and GPCR antagonists can be developed as an effective anti-EBOV/MARV therapy. IMPORTANCE Infection of Ebola virus and Marburg virus can cause severe illness in humans with a high mortality rate, and currently there is no FDA-approved vaccine or therapeutic treatment available. The 2013-2015 epidemic in West Africa underscores a lack of our understanding in the infection and pathogenesis of these viruses and the urgency of drug discovery and development. In this study, we have identified numerous inhibitors that are known G protein-coupled receptor (GPCR) antagonists targeting different GPCRs. These inhibitors can effectively block replication of both infectious EBOV and MARV, indicating a broad antiviral activity of the GPCR antagonists. Our results strongly suggest that GPCRs play a critical role in filoviral entry and GPCR antagonists can be developed as an effective anti-EBOV/MARV therapy. PMID:26202243

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

PubMed

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

2015-10-01

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

Antidepressant-like effect of the extract from leaves of Schinus molle L. in mice: evidence for the involvement of the monoaminergic system.

PubMed

Machado, Daniele G; Kaster, Manuella P; Binfaré, Ricardo W; Dias, Munique; Santos, Adair R S; Pizzolatti, Moacir G; Brighente, Inês M C; Rodrigues, Ana Lúcia S

2007-03-30

Schinus molle L. (Anacardiaceae), among other uses, is popularly employed for the treatment of depression. In this study, the antidepressant-like effect of the hexanic extract from leaves of S. molle was investigated in the mouse tail suspension test (TST), a predictive model of depression. The immobility time in the TST was significantly reduced by the extract (dose range 30-600 mg/kg, p.o.), without accompanying changes in ambulation when assessed in an open-field test. The efficacy of extract was found to be comparable to that of fluoxetine (10 mg/kg, p.o.). The anti-immobility effect of the extract (100 mg/kg, p.o.) was prevented by pretreatment of mice with p-chlorophenylalanine methyl ester (PCPA, 100 mg/kg, i.p., an inhibitor of serotonin synthesis, for four consecutive days), NAN-190 (0.5 mg/kg, i.p., a 5-HT(1A) receptor antagonist), WAY100635 (0.1 mg/kg, s.c., a selective 5-HT(1A) receptor antagonist), ketanserin (5 mg/kg, i.p., a 5-HT(2A/2C) receptor antagonist), MDL72222 (0.1 mg/kg, i.p., a 5-HT(3) receptor antagonist), prazosin (1 mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., a D(1) receptor antagonist) or sulpiride (50 mg/kg, i.p., a D(2) receptor antagonist). It may be concluded that the hexanic extract of S. molle produces an antidepressant-like effect that seems to be dependent on its interaction with the serotonergic, noradrenergic and dopaminergic systems. These results provide evidence that the extract from S. molle shares with established antidepressants some pharmacological effects, at least at a preclinical level.

Structural determinants for antagonist pharmacology that distinguish the rho1 GABAC receptor from GABAA receptors.

PubMed

Zhang, Jianliang; Xue, Fenqin; Chang, Yongchang

2008-10-01

GABA receptor (GABAR) types C (GABACR) and A (GABAAR) are both GABA-gated chloride channels that are distinguished by their distinct competitive antagonist properties. The structural mechanism underlying these distinct properties is not well understood. In this study, using previously identified binding residues as a guide, we made individual or combined mutations of nine binding residues in the rho1 GABACR subunit to their counterparts in the alpha1beta2gamma2 GABAAR or reverse mutations in alpha1 or beta2 subunits. The mutants were expressed in Xenopus laevis oocytes and tested for sensitivities of GABA-induced currents to the GABAA and GABAC receptor antagonists. The results revealed that bicuculline insensitivity of the rho1 GABACR was mainly determined by Tyr106, Phe138 and Phe240 residues. Gabazine insensitivity of the rho1 GABACR was highly dependent on Tyr102, Tyr106, and Phe138. The sensitivity of the rho1 GABACR to 3-aminopropyl-phosphonic acid and its analog 3-aminopropyl-(methyl)phosphinic acid mainly depended on residues Tyr102, Val140, FYS240-242, and Phe138. Thus, the residues Tyr102, Tyr106, Phe138, and Phe240 in the rho1 GABACR are major determinants for its antagonist properties distinct from those in the GABAAR. In addition, Val140 in the GABACR contributes to 3-APA binding. In conclusion, we have identified the key structural elements underlying distinct antagonist properties for the GABACR. The mechanistic insights were further extended and discussed in the context of antagonists docking to the homology models of GABAA or GABAC receptors.

Importance of agonists in alpha-adrenoceptor classification and localisation of alpha1-adrenoceptors in human prostate.

PubMed

McGrath, J C; Naghadeh, M A; Pediani, J D; Mackenzie, J F; Daly, C J

1999-01-01

alpha-Adrenoceptor blocker drugs are commonly used in the clinical (non-surgical) treatment of BPH. alpha1-adrenoceptors were originally sub-divided using agonists but, subsequently, were sub-divided using only antagonists in ligand-ligand interactions, which did not require agonists at all. Ultimately, proof that adrenoceptors are functional receptors for the natural ligands, noradrenaline and adrenaline, requires that agonists be used. The earlier excitement engendered by finding varying agonist potency series in different tissues has not been revisited to place it in the context of current concepts of alpha1-adrenoceptor subtypes. This review will consider the advantages and limitations of different agonists for the study of alpha1-adrenoceptor subtypes including 'extreme' examples where the archetypal alpha1-adrenoceptor agonist phenylephrine activates alpha2-adrenoceptors and others where UK14304, often the alpha2-adrenoceptor agonist of choice, activates alpha1-adrenoceptors. New work will also be presented showing the interaction between agonists and the fluorescent alpha1-adrenoceptor antagonist QAPB. This introduces the novel point of view of studying the displacement of antagonists by agonists. Possible errors in antagonist classification arising from complexity in the actions of agonists and the recently developed method of fluorescent ligand binding on isolated living human prostatic smooth muscle cells will be discussed.

Monoamines and neuropeptides interact to inhibit aversive behaviour in Caenorhabditis elegans.

PubMed

Mills, Holly; Wragg, Rachel; Hapiak, Vera; Castelletto, Michelle; Zahratka, Jeffrey; Harris, Gareth; Summers, Philip; Korchnak, Amanda; Law, Wenjing; Bamber, Bruce; Komuniecki, Richard

2012-02-01

Pain modulation is complex, but noradrenergic signalling promotes anti-nociception, with α(2)-adrenergic agonists used clinically. To better understand the noradrenergic/peptidergic modulation of nociception, we examined the octopaminergic inhibition of aversive behaviour initiated by the Caenorhabditis elegans nociceptive ASH sensory neurons. Octopamine (OA), the invertebrate counterpart of norepinephrine, modulates sensory-mediated reversal through three α-adrenergic-like OA receptors. OCTR-1 and SER-3 antagonistically modulate ASH signalling directly, with OCTR-1 signalling mediated by Gα(o). In contrast, SER-6 inhibits aversive responses by stimulating the release of an array of 'inhibitory' neuropeptides that activate receptors on sensory neurons mediating attraction or repulsion, suggesting that peptidergic signalling may integrate multiple sensory inputs to modulate locomotory transitions. These studies highlight the complexity of octopaminergic/peptidergic interactions, the role of OA in activating global peptidergic signalling cascades and the similarities of this modulatory network to the noradrenergic inhibition of nociception in mammals, where norepinephrine suppresses chronic pain through inhibitory α(2)-adrenoreceptors on afferent nociceptors and stimulatory α(1)-receptors on inhibitory peptidergic interneurons.

Monoamines and neuropeptides interact to inhibit aversive behaviour in Caenorhabditis elegans

PubMed Central

Mills, Holly; Wragg, Rachel; Hapiak, Vera; Castelletto, Michelle; Zahratka, Jeffrey; Harris, Gareth; Summers, Philip; Korchnak, Amanda; Law, Wenjing; Bamber, Bruce; Komuniecki, Richard

2012-01-01

Pain modulation is complex, but noradrenergic signalling promotes anti-nociception, with α2-adrenergic agonists used clinically. To better understand the noradrenergic/peptidergic modulation of nociception, we examined the octopaminergic inhibition of aversive behaviour initiated by the Caenorhabditis elegans nociceptive ASH sensory neurons. Octopamine (OA), the invertebrate counterpart of norepinephrine, modulates sensory-mediated reversal through three α-adrenergic-like OA receptors. OCTR-1 and SER-3 antagonistically modulate ASH signalling directly, with OCTR-1 signalling mediated by Gαo. In contrast, SER-6 inhibits aversive responses by stimulating the release of an array of ‘inhibitory' neuropeptides that activate receptors on sensory neurons mediating attraction or repulsion, suggesting that peptidergic signalling may integrate multiple sensory inputs to modulate locomotory transitions. These studies highlight the complexity of octopaminergic/peptidergic interactions, the role of OA in activating global peptidergic signalling cascades and the similarities of this modulatory network to the noradrenergic inhibition of nociception in mammals, where norepinephrine suppresses chronic pain through inhibitory α2-adrenoreceptors on afferent nociceptors and stimulatory α1-receptors on inhibitory peptidergic interneurons. PMID:22124329

Pretreatment with β-adrenergic receptor agonists facilitates induction of LTP and sharp wave ripple complexes in rodent hippocampus.

PubMed

Ul Haq, Rizwan; Anderson, Marlene; Liotta, Agustin; Shafiq, Maria; Sherkheli, Muhammad Azhar; Heinemann, Uwe

2016-12-01

Norepinephrine, is involved in the enhancement of learning and memory formation by regulating synaptic mechanisms through its ability to activate pre- and post-synaptic adrenergic receptors. Here we show that β-agonists of norepinephrine facilitate the induction of both associational LTP and sharp wave ripples (SPW-Rs) in acute slices of rat hippocampus in area CA3. Surprisingly, this facilitating effect persists when slices are only pretreated with β-receptor agonists followed by wash out and application of the unspecific β-adrenoreceptor (βAR) antagonist propranolol. During application of βAR agonists repeated stimulation resulted in facilitated induction of SPW-Rs. Since SPW-Rs are thought to be involved in memory replay we studied the effects of βAR-agonists on spontaneous SPW-Rs in murine hippocampus and found that amplitude and incidence of SPW-Rs increased. These effects involve cyclic-AMP and the activation of protein kinase A and suggest a supportive role in memory consolidation. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Evidence of changes in alpha-1/AT1 receptor function generated by diet-induced obesity.

PubMed

Juarez, Esther; Tufiño, Cecilia; Querejeta, Enrique; Bracho-Valdes, Ismael; Bobadilla-Lugo, Rosa A

2017-11-01

To study whether hypercaloric diet-induced obesity deteriorates vascular contractility of rat aorta through functional changes in α 1 adrenergic and/or AT1 Angiotensin II receptors. Angiotensin II- or phenylephrine-induced contraction was tested on isolated aorta rings with and without endothelium from female Wistar rats fed for 7 weeks with hypercaloric diet or standard diet. Vascular expression of Angiotensin II Receptor type 1 (AT1R), Angiotensin II Receptor type 2 (AT2R), Cyclooxygenase-1 (COX-1), Cyclooxygenase-2 (COX-2), inducible Nitric Oxide Synthase (iNOS) and endothelial Nitric Oxide Synthase (eNOS), as well as blood pressure, glucose, insulin and angiotensin II blood levels were measured. Diet-induced obesity did not significantly change agonist-induced contractions (Emax and pD 2 hypercaloric diet vs standard diet n.s.d.) of both intact (e+) or endothelium free (e-) vessels but significantly decrease both phenylephrine and angiotensin II contraction (Emax p < 0.01 hypercaloric diet vs standard diet) in the presence of both prazosin and losartan but only in endothelium-intact vessels. Diet-induced obesity did not change angiotensin II AT1, AT2 receptor proteins expression but reduced COX-1 and NOS2 ( p < 0.05 vs standard diet). Seven-week hypercaloric diet-induced obesity produces alterations in vascular adrenergic and angiotensin II receptor dynamics that suggest an endothelium-dependent adrenergic/angiotensin II crosstalk. These changes reflect early-stage vascular responses to obesity.

Effects of sympathetic nerve stimulation on long posterior ciliary artery blood flow in cats.

PubMed

Koss, Michael C

2002-04-01

A new technique using ultrasonic flowmetry was developed in order to directly measure blood flow in the long posterior ciliary artery (LPCA) of anesthetized cats. Basal LPCA blood flow averaged about 0.6 ml/min and was stable over the experimental period. Electrical stimulation of the cervical preganglionic cervical sympathetic nerve produced frequency-dependent anterior segment ocular vasoconstrictor responses. Ipsilateral nictitating membrane contractions were simultaneously measured as a well-established index of neural sympathetic activation. LPCA frequency-response relationships were shifted to the right in comparison with those for the nictitating membrane. When elicited at two min intervals, submaximal evoked responses of both systems were stable for more than 90 min. Ocular vasoconstrictor and nictitating membrane responses were blocked in a dose-dependent fashion by intravenous treatment with the non-selective a-adrenoceptor antagonist, phentolamine (0.3-3.0 mg/kg), as well as with the selective alpha1-adrenoceptor antagonist, prazosin (3-30 microg/kg). In contrast, neither evoked response was further antagonized by subsequent administration of the alpha2-adrenoceptor antagonist, yohimbine (500 microg/kg). These results demonstrate the usefulness of ultrasonic flowmetry to study mechanisms controlling ocular anterior segment circulation and suggest that, as previously established for the nictitating membrane and anterior choroid, adrenergic neurogenic vasoconstriction in tissues perfused by the LPCA is mediated predominantly by alpha1-adrenoceptors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

C-11 hydroxy ephedrine, introduced as the first clinically usable norepinephrine analogue, studies employing normal volunteers and patients with various cardiac disorders was found to valuable as a nonadreneric tracer. Simultaneously, animal studies been used to assess its use following ischemic injury in order to define neuronal damage. Current research focuses on the comparison of C-11 hydroxyephedrine with other neurotransmitters such as C-11 epinephrine and C-11 threohydroxyephedrine. Epinephrine is primarily stored in vesicles of the nerve terminal, while threo-hydroxyephedrine is only substrate to uptake I mechanism. Such a combination of radiotracers may allow the dissection of uptake I mechanism as wellmore » as vesicular storage. In parallel to the refinement of presynaptic tracers for the sympathetic nervous system, we are developing radiopharmaceuticals to delineate the adrenergic receptors in the heart. The combined evaluation of pre- and postsynaptic nerve function will improve our ability to identify abnormalides. We are currently developing a new radiosynthesis of the hydrophilic adrenergic receptor antagonist C-11 CGP-12177 which has been used by others for the visualization of adrenergic receptors in the heart. We are developing radiopharmaceuticals, for the delineation of presynaptic cholinergic nerve terminals. Derivatives of benzovesamicol have been labeled in our institution and are currently under investigation. The most promising agent is F-18 benzovesamicol (FEBOBV) which allows the visualization of parasympathetic nerve terminals in the canine heart as demonstrated by, preliminary PET data.« less

Laboratory practical to study the differential innervation pathways of urinary tract smooth muscle.

PubMed

Rembetski, Benjamin E; Cobine, Caroline A; Drumm, Bernard T

2018-06-01

In the mammalian lower urinary tract, there is a reciprocal relationship between the contractile state of the bladder and urethra. As the bladder fills with urine, it remains relaxed to accommodate increases in volume, while the urethra remains contracted to prevent leakage of urine from the bladder to the exterior. Disruptions to the normal contractile state of the bladder and urethra can lead to abnormal micturition patterns and urinary incontinence. While both the bladder and urethra are smooth-muscle organs, they are differentially contracted by input from cholinergic and sympathetic nerves, respectively. The laboratory practical described here provides an experiential approach to understanding the anatomy of the lower urinary tract. Several key factors in urinary tract physiology are outlined, e.g., the bladder is contracted by activation of the parasympathetic pathway via cholinergic stimulation on muscarinic receptors, whereas the urethra is contracted by activation of the sympathetic pathway via adrenergic stimulation on α 1 -adrenoceptors. This is achieved by measuring the force generated by bladder and urethra smooth muscle to demonstrate that acetylcholine contracts the smooth muscle of the bladder, whereas adrenergic agonists contract the urethral smooth muscle. An inhibition of these effects is also demonstrated by application of the muscarinic receptor antagonist atropine and the α 1 -adrenergic receptor blocker phentolamine. A list of suggested techniques and exam questions to evaluate student understanding on this topic is also provided.

Vagus nerve stimulation enhances perforant path-CA3 synaptic transmission via the activation of β-adrenergic receptors and the locus coeruleus.

PubMed

Shen, Huilian; Fuchino, Yuta; Miyamoto, Daisuke; Nomura, Hiroshi; Matsuki, Norio

2012-05-01

Vagus nerve stimulation (VNS) is an approved treatment for epilepsy and depression and has cognition-enhancing effects in patients with Alzheimer's disease. The hippocampus is widely recognized to be related to epilepsy, depression, and Alzheimer's disease. One possible mechanism of VNS involves its effect on the hippocampus; i.e. it increases the release of noradrenaline in the hippocampus. However, the effect of VNS on synaptic transmission in the hippocampus is unknown. To determine whether VNS modulates neurotransmission in the hippocampus, we examined the effects of VNS on perforant path (PP)-CA3 synaptic transmission electrophysiologically in anaesthetized rats. VNS induces a persistent enhancement of PP-CA3 field excitatory post-synaptic potentials (fEPSPs). Arc, an immediate early gene, was used to identify active brain regions after VNS. The locus coeruleus (LC), which contains the perikarya of noradrenergic projections, harboured more Arc-positive cells, as measured by in-situ hybridization, after 10-min VNS. In addition, electrical lesions of LC neurons or intraventricular administration of the β-adrenergic receptor antagonist timolol prevented the enhancement of PP-CA3 responses by VNS. In conclusion, the protracted increase in PP-CA3 synaptic transmission that is induced by VNS entails activation of the LC and β-adrenergic receptors. Our novel findings suggest that information from the periphery modulates synaptic transmission in the CA3 region of the hippocampus.

A high-level prokaryotic expression system: synthesis of human interleukin 1 alpha and its receptor antagonist.

PubMed

Birikh, K R; Lebedenko, E N; Boni, I V; Berlin, Y A

1995-10-27

Synthetic intronless genes, coding for human interleukin 1 alpha (IL 1 alpha) and interleukin 1 receptor antagonist (IL1ra), have been expressed efficiently in a specially designed prokaryotic vector, pGMCE (a pGEM1 derivative), where the target gene forms the second part of a two-cistron system. The first part of the system is a translation enhancer-containing mini-cistron, whose termination codon overlaps the start codon of the target gene. In the case of the IL1 alpha gene, the high expression level is largely due to the direct efficient translation initiation at the second cistron, whereas with the IL1ra gene in the same system, the proximal translation initiation region (TIR) provides a high level of coupled expression of the target gene. Thus, pGMCE is a potentially versatile vector for direct prokaryotic expression.

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

Guanfacine ameliorates hypobaric hypoxia induced spatial working memory deficits.

PubMed

Kauser, H; Sahu, S; Kumar, S; Panjwani, U

2014-01-17

Hypobaric hypoxia (HH) observed at high altitude causes mild cognitive impairment specifically affecting attention and working memory. Adrenergic dysregulation and neuronal damage in prefrontal cortex (PFC) has been implicated in hypoxia induced memory deficits. Optimal stimulation of alpha 2A adrenergic receptor in PFC facilitates the spatial working memory (SWM) under the conditions of adrenergic dysregulation. Therefore the present study was designed to test the efficacy of alpha 2A adrenergic agonist, Guanfacine (GFC), to restore HH induced SWM deficits and PFC neuronal damage. The rats were exposed to chronic HH equivalent to 25,000ft for 7days in an animal decompression chamber and received daily treatment of GFC at a dose of 1mg/kg body weight via the intramuscular route during the period of exposure. The cognitive performance was assessed by Delayed Alternation Task (DAT) using T-Maze and PFC neuronal damage was studied by apoptotic and neurodegenerative markers. Percentage of correct choice decreased significantly while perseverative errors showed a significant increase after 7days HH exposure, GFC significantly ameliorated the SWM deficits and perseveration. There was a marked and significant increase in chromatin condensation, DNA fragmentation, neuronal pyknosis and fluoro Jade positive cells in layer II of the medial PFC in hypoxia exposed group, administration of GFC significantly reduced the magnitude of these changes. Modulation of adrenergic mechanisms by GFC may serve as an effective countermeasure in amelioration of prefrontal deficits and neurodegenerative changes during HH. © 2013.

Yohimbine Impairs Extinction of Cocaine-Conditioned Place Preference in an [alpha] [subscript 2]-Adrenergic Receptor Independent Process

ERIC Educational Resources Information Center

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

2008-01-01

Extinction, a form of learning that has the ability to reshape learned behavior based on new experiences, has been heavily studied utilizing fear learning paradigms. Mechanisms underlying extinction of positive-valence associations, such as drug self-administration and place preference, are poorly understood yet may have important relevance to…

Activation of alpha2 adrenergic receptors suppresses fear conditioning: expression of c-Fos and phosphorylated CREB in mouse amygdala.

PubMed

Davies, M Frances; Tsui, Janet; Flannery, Judy A; Li, Xiangqi; DeLorey, Timothy M; Hoffman, Brian B

2004-02-01

alpha(2) adrenergic agonists such as dexmedetomidine generally suppress noradrenergic transmission and have sedative, analgesic, and antihypertensive properties. Considering the importance of the neurotransmitter norepinephrine in forming memories for fearful events, we have investigated the acute and chronic effects of dexmedetomidine on discrete cue and contextual fear conditioning in mice. When administered before training, dexmedetomidine (10-20 microg/kg, i.p.) selectively suppressed discrete cue fear conditioning without affecting contextual memory. This behavioral change was associated with a decrease in memory retrieval-induced expression of c-Fos and P-CREB in the lateral, basolateral, and central nuclei of the amygdala. Dexmedetomidine's action on discrete cue memory did not occur in alpha(2A) adrenoceptor knockout (KO) mice. When dexmedetomidine was administered after training, it suppressed contextual memory, an effect that did not occur in alpha(2A) adrenoceptor KO mice. We conclude that dexmedetomidine, acting at alpha(2A) adrenoceptors, must be present during the encoding process to decrease discrete cue fear memory; however, its ability to suppress contextual memory is likely the result of blocking the consolidation process. The ability of alpha(2) agonists to suppress fear memory may be a valuable property clinically in order to suppress the formation of memories during stressful situations.

Pharmacological and pharmacokinetic characterization of 2-piperazine-alpha-isopropyl benzylamine derivatives as melanocortin-4 receptor antagonists.

PubMed

Chen, Chen; Tucci, Fabio C; Jiang, Wanlong; Tran, Joe A; Fleck, Beth A; Hoare, Sam R; Wen, Jenny; Chen, Takung; Johns, Michael; Markison, Stacy; Foster, Alan C; Marinkovic, Dragan; Chen, Caroline W; Arellano, Melissa; Harman, John; Saunders, John; Bozigian, Haig; Marks, Daniel

2008-05-15

A series of 2-piperazine-alpha-isopropylbenzylamine derivatives were synthesized and characterized as melanocortin-4 receptor (MC4R) antagonists. Attaching an amino acid to benzylamines 7 significantly increased their binding affinity, and the resulting compounds 8-12 bound selectively to MC4R over other melanocortin receptor subtypes and behaved as functional antagonists. These compounds were also studied for their permeability using Caco-2 cell monolayers and metabolic stability in human liver microsomes. Most compounds exhibited low permeability and high efflux ratio possibly due to their high molecular weights. They also showed moderate metabolic stability which might be associated with their moderate to high lipophilicity. Pharmacokinetic properties of these MC4R antagonists, including brain penetration, were studied in mice after oral and intravenous administrations. Two compounds identified to possess high binding affinity and selectivity, 10d and 11d, were studied in a murine cachexia model. After intraperitoneal (ip) administration of 1mg/kg dose, mice treated with 10d had significantly more food intake and weight gain than the control animals, demonstrating efficacy by blocking the MC4 receptor. Similar in vivo effects were also observed when 11d was dosed orally at 20mg/kg. These results provide further evidence that a potent and selective MC4R antagonist has potential in the treatment of cancer cachexia.

Catestatin (chromogranin A344-364) is a novel cardiosuppressive agent: inhibition of isoproterenol and endothelin signaling in the frog heart

PubMed Central

Mazza, Rosa; Gattuso, Alfonsina; Mannarino, Cinzia; Brar, Bhawanjit K.; Barbieri, Sandra Francesca; Tota, Bruno; Mahata, Sushil K.

2008-01-01

The catecholamine release-inhibitory catestatin [Cts; human chromogranin (Cg) A352-372, bovine CgA344-364] is a vasoreactive and anti-hypertensive peptide derived from CgA. Using the isolated avascular frog heart as a bioassay, in which the interactions between the endocardial endothelium and the subjacent myocardium can be studied without the confounding effects of the vascular endothelium, we tested the direct cardiotropic effects of bovine Cts and its interaction with β-adrenergic (isoproterenol, ISO) and endothelin-1 (ET-1) signaling. Cts dose-dependently decreased stroke volume and stroke work, with a threshold concentration of 11 nM, approaching the in vivo level of the peptide. Cts reduced contractility by inhibiting phosphorylation of phospholamban (PLN). Furthermore, the Cts effect was abolished by pretreatment with either nitric oxide synthase (NG-monomethyl-l-arginine) or guanylate cyclase (ODQ) inhibitors, or an ETB receptor (ETBR) antagonist (BQ-788). Cts also noncompetitively inhibited the positive inotropic action of ISO. In addition, Cts inhibited the positive inotropic effect of ET-1, mediated by ETA receptors, and did not alter the negative inotropic ET-1 influence mediated by ETBR. Cts action through ETBR was further suggested when, in the presence of BQ-788, Cts failed to inhibit the positive inotropism of both ISO and ET-1 stimulation and PLN phosphorylation. We concluded that the cardiotropic actions of Cts, including the β-adrenergic and ET-1 antagonistic effects, support a novel role of this peptide as an autocrine-paracrine modulator of cardiac function, particularly when the stressed heart becomes a preferential target of both adrenergic and ET-1 stimuli. PMID:18469147

NK2 tachykinin receptors mediate contraction of the pig intravesical ureter: tachykinin-induced enhancement of non-adrenergic non-cholinergic excitatory neurotransmission.

PubMed

Bustamante, S; Orensanz, L M; Barahona, M V; García-Sacristán, A; Hernández, M

2001-01-01

The current study was designed to characterize the functionally active tachykinin receptors involved in tachykinin-elicited contractions in the pig intravesical ureter, and to investigate the possible modulation exerted by the natural tachykinins substance P (SP) and neurokinin A (NKA) on the non-adrenergic non-cholinergic (NANC) excitatory ureteral neurotransmission. In pig intravesical ureteral strips pretreated with phosphoramidon (10(-5) mol/L) to block the endopeptidase activities, isometric force recordings showed that SP, NKA, and the NK2 receptor selective agonist [beta-Ala(8)]-NKA (4-10), all three induced contractions, with the following potency order: NKA > [beta-Ala(8) ]-NKA (4-10) > SP. [Sar(9), Met(O(2))(11)]-SP and senktide, selective agonists of the NK1 and NK3 receptors, respectively, failed to modify the ureteral tone. Urothelium removal and incubation with tetrodotoxin (10(-6) mol/L), phentolamine (10(-7) mol/L), propranolol (3 x 10(-6) mol/L), atropine (10(-7) mol/L) and indomethacin (3 x 10(-6) mol/L), did not alter the contraction induced by a submaximal (10(-7) mol/L) dose of [beta-Ala(8)]-NKA (4-10). MEN 10,376 (10(-8)-10(-7) mol/L), a NK2 receptor antagonist, reduced the contraction to 3 x 10(-8) mol/L NKA. GR 82334 (10(-6) -10(-5) mol/L) and SR 142801 (10(-8)-10(-7) mol/L), selective antagonists of the NK1 and NK3 receptors, respectively, did not modify that contraction. In pig intravesical ureteral strips in NANC conditions, SP and NKA induced a potentiation of the contractions to electrical field stimulation (EFS) and to exogenous ATP. The results suggest that the tachykinins evoke a direct contraction of pig intravesical ureteral strips through NK2 receptors located in the smooth muscle. SP and NKA exert an enhancement of the NANC excitatory neurotransmission of the pig intravesical ureter.

Strychnine, but not PMBA, inhibits neuronal nicotinic acetylcholine receptors expressed by rabbit retinal ganglion cells.

PubMed

Renna, J M; Strang, C E; Amthor, F R; Keyser, K T

2007-01-01

Strychnine is considered a selective competitive antagonist of glycine gated Cl- channels (Saitoh et al., 1994) and studies have used strychnine at low micromolar concentrations to study the role of glycine in rabbit retina (Linn, 1998; Protti et al., 2005). However, other studies have shown that strychnine, in the concentrations commonly used, is also a potent competitive antagonist of alpha7 nicotinic acetylcholine receptors (nAChRs; Matsubayashi et al., 1998). We tested the effects of low micromolar concentrations of strychnine and 3-[2'-phosphonomethyl[1,1'-biphenyl]-3-yl] alanine (PMBA), a specific glycine receptor blocker (Saitoh et al., 1994; Hosie et al., 1999) on the activation of both alpha7 nAChRs on retinal ganglion cells and on ganglion cell responses to a light flash. Extracellular recordings were obtained from ganglion cells in an isolated retina/choroid preparation and 500 microM choline was used as an alpha7 agonist (Alkondon et al., 1997). We recorded from brisk sustained and brisk transient OFF cells, many of which have been previously shown to have alpha7 receptors (Strang et al., 2005). Further, we tested the effect of strychnine, PMBA and alpha-bungarotoxin on the binding of tetramethylrhodamine alpha-bungarotoxin in the inner plexiform layer. Our data indicates that strychnine, at doses as low as 1.0 microM, can inhibit the alpha7 nAChR-mediated response to choline, but PMBA at concentrations as high as 0.4 microM does not. Binding studies show strychnine and alpha-bungarotoxin inhibit binding of labeled alpha-bungarotoxin in the IPL. Thus, the effects of strychnine application may be to inhibit glycine receptors expressed by ganglion cell or to inhibit amacrine cell alpha7 nAChRs, both of which would result in an increase in the ganglion cell responses. Further research will be required to disentangle the effects of strychnine previously believed to be caused by a single mechanism of glycine receptor inhibition.

Organophosphorus poisoning (acute).

PubMed

2007-03-01

Acute organophosphorus poisoning occurs after dermal, respiratory, or oral exposure to either low-volatility pesticides (e.g. chlorpyrifos, dimethoate) or high-volatility nerve gases (e.g. sarin, tabun). Most cases occur in resource-poor countries as a result of occupational or deliberate exposure to organophosphorus pesticides. We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for acute organophosphorus poisoning? We searched: Medline, Embase, The Cochrane Library and other important databases up to August 2006 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 22 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: activated charcoal, alpha2 adrenergic receptor agonists, atropine, benzodiazepines, butyrylcholinesterase replacement therapy, cathartics, extracorporeal clearance, gastric lavage, glycopyrronium bromide, ipecacuanha, magnesium sulphate, milk or other home remedies, N-methyl-D-aspartate receptor antagonists, organophosphorus hydrolases, oximes, sodium bicarbonate, washing the poisoned person and removing contaminated clothing.

Organophosphorus poisoning (acute).

PubMed

Blain, Peter G

2011-05-17

Acetylcholinesterase inhibition by organophosphorus pesticides or organophosphate nerve agents can cause acute parasympathetic system dysfunction, muscle weakness, seizures, coma, and respiratory failure. Prognosis depends on the dose and relative toxicity of the specific compound, as well as pharmacokinetic factors. We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for acute organophosphorus poisoning? We searched: Medline, Embase, The Cochrane Library, and other important databases up to April 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 62 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: activated charcoal (single or multiple doses), alpha(2) adrenergic receptor agonists, atropine, benzodiazepines, butyrylcholinesterase replacement therapy, cathartics, extracorporeal clearance, gastric lavage, glycopyrronium bromide (glycopyrrolate), ipecacuanha (ipecac), magnesium sulphate, milk or other home remedy immediately after ingestion, N-methyl-D-aspartate receptor antagonists, organophosphorus hydrolases, oximes, removing contaminated clothes and washing the poisoned person, and sodium bicarbonate.

[The influence of single moderate exercise on the sympathetic nervous system activity in patients with essential hypertension].

PubMed

Gajek, Jacek; Zyśko, Dorota

2002-12-01

Sympathetic nervous system may play an important role in development and maintenance of hypertension. Its activity can be assessed by plasma levels of catecholamines, neuropeptide Y (NPY) and adrenergic receptor density. Hypertensive subjects may be more prone to reveal overactivity of sympathetic nervous system, for instance as a result of physical stress. The aim of the study was to determine the activity of sympathetic nervous system in young patients with newly recognized, untreated mild hypertension. The study was carried out in 22 patients (age 38.5 +/- 10.3 years) and 20 normotensive volunteers (age 38.5 +/- 8.6 years) as a control group, matched for sex. Density of alpha 2- and beta-adrenergic receptors using 3H-yohimbine and 125I-cyanopindolol respectively, total catecholamines and plasma renin activity using radioenzymatic assay, neuropeptide Y and aldosterone using radioimmunoassay were assessed in the blood taken in the supine position and after moderate bicycle ergometer exercise. Plasma concentration of NPY at rest did not differ between the groups, but increased significantly after exercise and was greater in hypertensive patients (p < 0.05). The density of alpha 2- and beta-adrenergic receptors at rest and after exercise in hypertensive subjects was unchanged when comparing to healthy individuals. The plasma concentrations of endogenous catecholamines, plasma renin activity and aldosterone level increase during exercise in both studied groups (p < 0.05). Aldosterone level was higher in hypertensive patients at rest (p < 0.05). There was a negative correlation between baseline aldosterone and NPY levels in hypertensive patients (r = -0.44, p < 0.05). Moderate exercise in hypertensive subjects causes the hyperactivity of sympathetic nervous system expressed as increase of NPY plasma level.

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

PubMed Central

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

2015-01-01

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

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.

BM-520, an original TXA2 modulator, inhibits the action of thromboxane A2 and 8-iso-prostaglandin F2alphain vitro and in vivo on human and rodent platelets, and aortic vascular smooth muscles from rodents.

PubMed

Rolin, S; Hanson, J; Vastersaegher, C; Cherdon, C; Pratico, D; Masereel, B; Dogne, J M

2007-08-01

Thromboxane A(2) (TXA(2)) and 8-iso-PGF(2alpha) are two prostanoid agonists of the thromboxane A(2) receptor (TP), whose activation has been involved in platelet aggregation and atherosclerosis. Agents able to counteract the actions of these agonists are of great interest in the treatment and prevention of cardiovascular events. Here, we investigated in vitro and in vivo the pharmacological profile of BM-520, a new TP antagonist. In our experiments, this compound showed a great binding affinity for human washed platelets TP receptors, and prevented human platelet activation and aggregation induced by U-46619, arachidonic acid and 8-iso-PGF(2alpha). The TP receptor antagonist property of BM-520 was confirmed by its relaxing effect on rat aorta smooth muscle preparations precontracted with U-46619 and 8-iso-PGF(2alpha). Further, its TP antagonism was also demonstrated in vivo in guinea pig after a single intravenous injection (10 mg kg(-1)). We conclude that this novel TP antagonist could be a promising therapeutic tool in pathologies such as atherosclerosis where an increased production of TXA(2) and 8-iso-PGF(2alpha), as well as TP activation are well-established pathogenic events.

Dopamine modulates male sexual behavior in Japanese quail in part via actions on noradrenergic receptors.

PubMed

Cornil, Charlotte A; Dejace, Christel; Ball, Gregory F; Balthazart, Jacques

2005-08-30

In rats, dopamine (DA) facilitates male sexual behavior through its combined action on D1- and D2-like receptors, in the medial preoptic area (MPOA) as well as other brain areas. In Japanese quail, systemic injections of dopaminergic drugs suggested a similar pharmacology but central injections have never been performed. Recent electrophysiological experiments demonstrated that DA effects in the MPOA of quail are mediated mainly through the activation of alpha2-noradrenergic receptors. Previous studies of DA action on behavior used specific dopaminergic agonists/antagonists and therefore unintentionally avoided the potential cross-reaction with alpha2-receptors. The present study was thus designed to investigate directly the effects of DA on male sexual behavior and to test whether the interaction of DA with heterologous receptors affects this behavior. Intracerebroventricular (i.c.v.) injection of DA or NE inhibited copulation in a dose-dependent manner. Systemic injections of yohimbine, an alpha2-noradrenergic antagonist, modulated copulation in a bimodal manner depending on the dose injected. Interestingly, a behaviorally ineffective dose of yohimbine markedly reduced the inhibitory effects of DA when injected 15min before. Together, these results show for the first time that i.c.v. injections of DA itself inhibit male sexual behavior in quail and suggest that the interaction of DA with alpha2-receptors has behavioral significance.

The antinociceptive effect of zolpidem and zopiclone in mice.

PubMed

Pick, Chaim G; Chernes, Yakov; Rigai, Tova; Rice, Kenner C; Schreiber, Shaul

2005-07-01

Zolpidem and zopiclone are two of a newer hypno-sedative class of drugs, the "Z compounds". Their use for the treatment of short-term insomnia has been expanding constantly during the last two decades. The "Z compounds" are considered to cause less significant rebound insomnia or tolerance than the conventional hypnotic benzodiazepines. Their possible antinociceptive effect and interaction with the opioid system has not been studied yet. Our results demonstrate a significant difference between the antinociceptive properties of zopiclone and zolpidem when injected s.c. in the hotplate analgesic assay in mice. Zopiclone induced a weak, dose-dependent antinociceptive effect, antagonized only by the alpha2-adrenergic receptor antagonist yohimbine. Zolpidem induced a weak, biphasic dose-dependent antinociceptive effect, antagonized primarily by the non-selective opioid antagonist naloxone and by yohimbine. The weak antinociceptive effect of both drugs, evident only at very high doses (far beyond those used clinically to induce sleep), implies no clinical use for zopiclone or zolpidem in the management of pain. However, the possible interaction of zolpidem with the opioid system should be further investigated (in behavioral models, which do not overlap with the acute-pain antinociception model we used), both for possible side effects in special populations (i.e. elderly) and for possible drug-drug interactions, in order to minimize possible hazards and maximize clinical beneficial effects of its use for sleep.

Impairment of contextual conditioned fear extinction after microinjection of alpha-1-adrenergic blocker prazosin into the medial prefrontal cortex.

PubMed

Do-Monte, Fabrício H M; Allensworth, Melody; Carobrez, Antônio P

2010-07-29

Long-lasting memories of aversive or stressful events have been associated with the noradrenergic system activation. Alpha-1-adrenergic antagonist prazosin has successfully been used in the last years to treat anxiety disorders related to aversive memories recurrence in humans. Contextual conditioned fear extinction paradigm in rats has been used to better understand the mechanisms involved in the attenuation of defensive behaviour after a traumatic situation. Here we investigated the effects of systemic administration of prazosin in the fear extinction processes. Rats were previously paired in a contextual fear conditioning box (1 footshock, 1 mA, 2s duration), further returning to the same box during three consecutive days receiving an intraperitoneal injection of vehicle or prazosin 30 min before (acquisition of extinction; 0.1 or 0.5mg/kg) or immediately after (consolidation of extinction, 0.5 or 1.5mg/kg) each extinction session (10 min). On the last day, all animals were re-exposed undrugged to the apparatus. Since the medial prefrontal cortex (mPFC) has been described as a key structure in the modulation of conditioned fear extinction, the effects of intra-mPFC microinjection (0.2 microl per side) of vehicle (PBS) or prazosin (0.75 or 2.5 nmol) in the acquisition of fear extinction (10 min before extinction session 1) were further evaluated. Subjects were drug-free re-exposed to the same box in the next day (extinction session 2). The percentage of freezing time was used as the memory retention parameter. The results showed that either systemic or intra-mPFC-alpha-1-adrenergic blockade increased the freezing time in the last extinction sessions, suggesting impairment of the extinction of contextual conditioned fear in rats. Copyright 2010 Elsevier B.V. All rights reserved.

Possible involvements of glutamate and adrenergic receptors on acute toxicity of methylphenidate in isolated hippocampus and cerebral cortex of adult rats.

PubMed

Motaghinejad, Majid; Motevalian, Manijeh; Shabab, Behnaz

2017-04-01

Neurodegeneration induced by methylphenidate (MPH), as a central stimulant with unknown long-term consequences, in adult rats' brain and the possible mechanisms involved were studied. Rats were acutely treated with MPH in the presence and absence of some receptor antagonists such as ketamine, topiramate, yohimbine, and haloperidol. Motor activity and anxiety level in rats were monitored. Antioxidant and inflammatory parameters were also measured in isolated hippocampus and cerebral cortex. MPH-treated groups (10 and 20 mg/kg) demonstrated anxiety-like behavior and increased motor activity. MPH significantly increased lipid peroxidation, GSSG content, IL-1β and TNF-α levels in isolated tissues, and also significantly reduced GSH content, superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR) activities in hippocampus and cerebral cortex. Pretreatment of animals by receptor antagonists caused inhibition of MPH-induced motor activity disturbances and anxiety-like behavior. Pretreatment of animals by ketamine, topiramate, and yohimbine inhibited the MPH-induced oxidative stress and inflammation; it significantly decreased lipid peroxidation, GSSG level, IL-1β and TNF-α levels and increased GSH content, SOD, GPx, and GR activities in hippocampus and cerebral cortex of acutely MPH-treated rats. Pretreatment with haloperidol did not cause any change in MPH-induced oxidative stress and inflammation. In conclusion, acute administration of high doses of MPH can cause oxidative and inflammatory changes in brain cells and induce neurodegeneration in hippocampus and cerebral cortex of adult rats and these changes might probably be mediated by glutamate (NMDA or AMPA) and/or α 2 -adrenergic receptors. © 2016 Société Française de Pharmacologie et de Thérapeutique.

Antagonism at NMDA receptors, but not β-adrenergic receptors, disrupts the reconsolidation of pavlovian conditioned approach and instrumental transfer for ethanol-associated conditioned stimuli.

PubMed

Milton, Amy L; Schramm, Moritz J W; Wawrzynski, James R; Gore, Felicity; Oikonomou-Mpegeti, Faye; Wang, Nancy Q; Samuel, Daniel; Economidou, Daina; Everitt, Barry J

2012-02-01

Reconsolidation is the process by which memories require restabilisation following destabilisation at retrieval. Since even old, well-established memories become susceptible to disruption following reactivation, treatments based upon disrupting reconsolidation could provide a novel form of therapy for neuropsychiatric disorders based upon maladaptive memories, such as drug addiction. Pavlovian cues are potent precipitators of relapse to drug-seeking behaviour and influence instrumental drug seeking through at least three psychologically and neurobiologically distinct processes: conditioned reinforcement, conditioned approach (autoshaping) and conditioned motivation (pavlovian-instrumental transfer or PIT). We have previously demonstrated that the reconsolidation of memories underlying the conditioned reinforcing properties of drug cues depends upon NMDA receptor (NMDAR)- and β-adrenergic receptor (βAR)-mediated signalling. However, it is unknown whether the drug cue memory representations underlying conditioned approach and PIT depend upon the same mechanisms. Using orally self-administered ethanol as a reinforcer in two separate experiments, we investigated whether the reconsolidation of the memories underlying conditioned approach and PIT requires βAR- and NMDAR-dependent neurotransmission. For ethanol self-administering but non-dependent rats, the memories underlying conditioned approach and PIT for a pavlovian drug cue were disrupted by the administration of the NMDAR antagonist MK-801, but not the administration of the βAR antagonist propranolol, when given in conjunction with memory reactivation. As for natural reinforcers, NMDARs are required for the reconsolidation of all aspects of pavlovian drug memories, but βARs are only required for the memory representation underlying conditioned reinforcement. These results indicate the potential utility of treatments based upon disrupting cue-drug memory reconsolidation in preventing relapse.

Regulation of 5alpha-reductase isoforms by oxytocin in the rat ventral prostate.

PubMed

Assinder, S J; Johnson, C; King, K; Nicholson, H D

2004-12-01

Oxytocin (OT) is present in the male reproductive tract, where it is known to modulate contractility, cell growth, and steroidogenesis. Little is known about how OT regulates these processes. This study describes the localization of OT receptor in the rat ventral prostate and investigates if OT regulates gene expression and/or activity of 5alpha-reductase isoforms I and II. The ventral prostates of adult male Wistar rats were collected following daily sc administration of saline (control), OT, a specific OT antagonist or both OT plus antagonist for 3 d. Expression of the OT receptor was identified in the ventral prostate by RT-PCR and Western blot, and confirmed to be a single active binding site by radioreceptor assay. Immunohistochemistry localized the receptor to the epithelium of prostatic acini and to the stromal tissue. Real-time RT-PCR determined that OT treatment significantly reduced expression of 5alpha-reductase I but significantly increased 5alpha-reductase II expression in the ventral prostate. Activity of both isoforms of 5alpha-reductase was significantly increased by OT, resulting in increased concentration of prostatic dihydrotestosterone. In conclusion, OT is involved in regulating conversion of testosterone to the biologically active dihydrotestosterone in the rat ventral prostate. It does so by differential regulation of 5alpha-reductase isoforms I and II.

5-HT2A receptor activation is necessary for CO2-induced arousal

PubMed Central

Smith, Haleigh R.; MacAskill, Amanda; Richerson, George B.

2015-01-01

Hypercapnia-induced arousal from sleep is an important protective mechanism pertinent to a number of diseases. Most notably among these are the sudden infant death syndrome, obstructive sleep apnea and sudden unexpected death in epilepsy. Serotonin (5-HT) plays a significant role in hypercapnia-induced arousal. The mechanism of 5-HT's role in this protective response is unknown. Here we sought to identify the specific 5-HT receptor subtype(s) involved in this response. Wild-type mice were pretreated with antagonists against 5-HT receptor subtypes, as well as antagonists against adrenergic, cholinergic, histaminergic, dopaminergic, and orexinergic receptors before challenge with inspired CO2 or hypoxia. Antagonists of 5-HT2A receptors dose-dependently blocked CO2-induced arousal. The 5-HT2C receptor antagonist, RS-102221, and the 5-HT1A receptor agonist, 8-OH-DPAT, attenuated but did not completely block CO2-induced arousal. Blockade of non-5-HT receptors did not affect CO2-induced arousal. None of these drugs had any effect on hypoxia-induced arousal. 5-HT2 receptor agonists were given to mice in which 5-HT neurons had been genetically eliminated during embryonic life (Lmx1bf/f/p) and which are known to lack CO2-induced arousal. Application of agonists to 5-HT2A, but not 5-HT2C, receptors, dose-dependently restored CO2-induced arousal in these mice. These data identify the 5-HT2A receptor as an important mediator of CO2-induced arousal and suggest that, while 5-HT neurons can be independently activated to drive CO2-induced arousal, in the absence of 5-HT neurons and endogenous 5-HT, 5-HT receptor activation can act in a permissive fashion to facilitate CO2-induced arousal via another as yet unidentified chemosensor system. PMID:25925320

Pharmacological studies of stonefish (Synanceja trachynis) venom.

PubMed

Hopkins, B J; Hodgson, W C; Sutherland, S K

1994-10-01

The present study was designed to examine some of the pharmacological properties of venom from the stonefish (Synanceja trachynis), with particular reference to the presence in the venom of pain-producing/enhancing substances. Stonefish venom (1-6 micrograms/ml) produced concentration-dependent contractile responses in guinea-pig isolated ileum. No tachyphylaxis, or reduction in responses with time, was observed to venom (3 micrograms/ml) in ileum. The response to venom (3 micrograms/ml) was not significantly affected by the histamine antagonist mepyramine (0.5 microM), or a preceding anaphylactic response. Mecamylamine, 5HT-desensitization or EXP3174 failed to have any significant effect on responses to venom (3 micrograms/ml). Responses to venom (3 micrograms/ml) were significantly inhibited by the cyclooxygenase inhibitor indomethacin (5 microM), the leukotriene D4 receptor antagonist FLP55712 (1 microM), the thromboxane A2 receptor antagonist GR32191B (1 microM), the muscarinic receptor antagonist atropine (10 nM) and the neurokinin-1 receptor antagonist CP96345 (0.1 microM). Venom (6 micrograms/ml) produced contractile responses in the rat isolated vas deferens which were abolished by the alpha 1-adrenoceptor antagonist prazosin (0.3 microM) and significantly potentiated by the neuronal uptake inhibitor DMI (1 microM). However, noradrenergic transmitter depletion with reserpine (5 mg/kg, i.p.) did not significantly inhibit responses to venom (6 micrograms/ml). Histamine fluorometric and phospholipase A2 assays failed to detect significant quantities of either substance in the venom. These results suggest that stonefish venom may cause the release of acetylcholine, substance P, and cyclooxygenase products, or contain components which act at these receptors. The venom also appears to contain a component which is a substrate for neuronal uptake and has a direct action at alpha 1-adrenoceptors.

Differential block of nicotinic synapses on B versus C neurones in sympathetic ganglia of frog by alpha-conotoxins MII and ImI.

PubMed

Tavazoie, S F; Tavazoie, M F; McIntosh, J M; Olivera, B M; Yoshikami, D

1997-03-01

1. The effects of two new acetylcholine receptor antagonists, alpha-conotoxin MII and alpha-conotoxin ImI, on nicotinic synaptic transmission in the 10th paravertebral sympathetic ganglion of the leopard frog (Rana pipiens) were examined. The preganglionic nerve was electrically stimulated (at low frequency, < or = 1 min-1, to avoid use-dependent changes) while compound action potentials of B and C neurones were monitored from the postganglionic nerve. 2. alpha-Conotoxins MII and ImI, at low micromolar concentrations, reversibly blocked both B and C waves, alpha-Conotoxin MII blocked the C wave more effectively than the B wave, whereas the potency of alpha-conotoxin ImI was opposite that of MII. The observation that nicotinic antagonists can differentially block synaptic transmission of B versus C neurones with opposite selectivities strongly suggests that these neurones possess distinct nicotinic receptors. 3. In addition to fast and slow B waves described by others. C waves with two temporally distinguishable components were present in our recordings. Each alpha-conotoxin affected fast and slow B waves similarly. Likewise, toxins did not discriminate between the two components of C waves. This suggests that all neurones within each major class (B or C) may have the same nicotinic receptors. 4. Synthetic forms of alpha-conotoxins MII and ImI were used in the present study. Their ease of synthesis and their specificities should make these toxins useful probes to investigate the various subtypes of neuronal nicotinic acetylcholine receptors.

Tolazoline decreases survival time during microwave-induced lethal heat stress in anesthetized rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jauchem, J.R.; Chang, K.S.; Frei, M.R.

1996-03-01

Effects of {alpha}-adrenergic antagonists have been studied during environmental heating but not during microwave-induced heating. Tolazoline may exert some of its effects via {alpha}-adrenergic blockade. In the present study, ketamine-anesthetized Sprague-Dawley rats were exposed to 2450-MHz microwaves at an average power density of 60 mW/cm{sup 2} (whole-body specific absorption rate of approximately 14 W/kg) until lethal temperatures were attained. The effects of tolazoline (10 mg/kg body weight) on physiological responses (including changes in body temperature, heart rate, blood pressure, and respiratory rate) were examined. Survival time was significantly shorter in the tolazoline group than in saline-treated animals. In general, heartmore » rate and blood pressure responses were similar to those that occur during environmental heat stress. Heart rate, however, was significantly elevated in animals that received tolazoline, both before and during terminal microwave exposure. It is possible that changes associated with the elevated heart rate (e.g., less cardiac filling) in tolazoline-treated animals resulted in greater susceptibility to microwave-induced heating and the lower survival time. 47 refs., 3 figs., 2 tabs.« less

Mood states, sympathetic activity, and in vivo beta-adrenergic receptor function in a normal population.

PubMed

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

2008-01-01

The purpose of this study was to examine the relationship between mood states and beta-adrenergic receptor function in a normal population. We also examined if sympathetic nervous system activity is related to mood states or beta-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). Beta-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 beta-adrenergic receptor sensitivity (i.e., higher chronotropic 25 dose values), but tension-anxiety was the only remaining independent predictor of beta-adrenergic receptor function after controlling for age, gender, ethnicity, and body mass index (BMI). Urinary norepinephrine excretion was unrelated to either mood states or beta-adrenergic receptor function. These findings replicate previous reports that anxiety is related to decreased (i.e., desensitized) beta-adrenergic receptor sensitivity, even after controlling for age, gender, ethnicity, and body mass index.

Comparative Exploration of the Structure-Activity Space of Cloned α-Like Octopamine Receptors from a Marine and a Terrestrial Arthropod.

PubMed

Dalwadi, Dhwanil A; Schetz, John A

2017-09-01

The α -like octopamine receptors (OctR) are believed to be the evolutionary precursor to the vertebrate α 2 -adrenergic receptors ( α 2 -ARs) based upon sequence similarity and the ability to interact with norepinephrine and a number of compounds that bind with high affinity to α 2 -ARs. Barnacles and fruit flies are two prominent model marine and terrestrial representatives of the Arthropoda phylum, and although α -like OctRs have been cloned from Balanus improvisus (BiOctR) and Drosophila melanogaster (DmOctR), little is known about the structure-activity space for these important species. A diverse panel of 22 probes spanning different structural classes were employed to interrogate the structure-activity of the BiOctR and DmOctR. While BiOctR and DmOctR exhibited similar functional profiles for mammalian biogenic amine G protein-coupled receptor agonists and antagonists, some ligands had dramatically different mechanisms of action. For instance, significant differences in the efficacy for some agonists were observed, including that vertebrate biogenic amines structurally related to octopamine acted as superagonists at the DmOctR but partial agonists at the BiOctR, and the two species diverged in their sensitivities to the α 2 -AR antagonist [ 3 H]rauwolscine. Furthermore, sodium enhanced [ 3 H]rauwolscine's interactions with the BiOctR, but not at a vertebrate α 2 -AR. Molecular mechanistic studies indicate that rauwolscine interacts with the BiOctR, DmOctR, and α 2C -adrenergic receptor at an allosteric site. In addition, compounds that acted as agonists at a cloned α -like BiOctR also induced a hyperactivity response in Balanus cyprids mediated by the α -like OctR, suggesting that the receptor may serve as a higher throughput proxy for discovering compounds with potential cyprid deterrent properties. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

Blocking of beta-2 adrenergic receptors hastens recovery from hypoglycemia-associated social withdrawal.

PubMed

Park, Min Jung; Guest, Christopher B; Barnes, Meredith B; Martin, Jonathan; Ahmad, Uzma; York, Jason M; Freund, Gregory G

2008-11-01

Hypoglycemia is associated with a variety of adverse behaviors including fatigue, confusion and social withdrawal. While these clinical symptoms are well characterized, the mechanism of their cause is not understood. Here we investigated how insulin-induced hypoglycemia causes social withdrawal. Male 8-12-week-old C57BL/6J mice were injected intraperitoneally (IP) with or without and/or insulin, norepinephrine (NE) and epinephrine (Epi), terbutaline and butoxamine with subsequent measurement of blood glucose, social withdrawal and plasma catecholamines. Insulin generated (0.75h post-injection) significant hypoglycemia with blood glucose nadirs of 64+/-4 and 48+/-5mg/dl for 0.8 and 1.2units/kg of insulin, respectively. Insulin (0.8 or 1.2units/kg) caused near total social withdrawal at 0.75h with full recovery not occurring until 4h (0.8units/kg) or 8h (1.2units/kg) post-insulin injection. Insulin also caused a marked elevation in plasma catecholamines. Basal 12h fasting NE and Epi were 287+/-38 and 350+/-47pg/ml, respectively. Insulin at 0.8units/kg increased plasma NE and Epi to 994+/-73 and 1842+/-473pg/ml, respectively. Administration of exogenous NE or Epi caused social withdrawal similar in magnitude to insulin. Importantly, administration of the beta-2 adrenergic receptor agonist terbutaline also caused social withdrawal while administration of the beta-2 adrenergic receptor antagonist butoxamine blocked NE-induced social withdrawal. Finally, butoxamine blocked insulin-induced social withdrawal. These data demonstrate that hypoglycemia-associated social withdrawal is dependent on catecholamines via a beta-2 receptor-mediated pathway.

β2-Adrenergic Receptor Knockout Mice Exhibit A Diabetic Retinopathy Phenotype

PubMed Central

Jiang, Youde; Zhang, Qiuhua; Liu, Li; Tang, Jie; Kern, Timothy S.; Steinle, Jena J.

2013-01-01

There is considerable evidence from our lab and others for a functional link between β-adrenergic receptor and insulin receptor signaling pathways in retina. Furthermore, we hypothesize that this link may contribute to lesions similar to diabetic retinopathy in that the loss of adrenergic input observed in diabetic retinopathy may disrupt normal anti-apoptotic insulin signaling, leading to retinal cell death. Our studies included assessment of neural retina function (ERG), vascular degeneration, and Müller glial cells (which express only β1 and β2-adrenergic receptor subtypes). In the current study, we produced β2-adrenergic receptor knockout mice to examine this deletion on retinal neurons and vasculature, and to identify specific pathways through which β2-adrenergic receptor modulates insulin signaling. As predicted from our hypothesis, β2-adrenergic receptor knockout mice display certain features similar to diabetic retinopathy. In addition, loss of β2-adrenergic input resulted in an increase in TNFα, a key inhibitor of insulin receptor signaling. Increased TNFα may be associated with insulin-dependent production of the anti-apoptotic factor, Akt. Since the effects occurred in vivo under normal glucose conditions, we postulate that aspects of the diabetic retinopathy phenotype might be triggered by loss of β2-adrenergic receptor signaling. PMID:23894672

Corticotropin-releasing factor (CRF) and α 2 adrenergic receptors mediate heroin withdrawal-potentiated startle in rats.

PubMed

Park, Paula E; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Schulteis, Gery; Koob, George F

2013-09-01

Anxiety is one of the early symptoms of opioid withdrawal and contributes to continued drug use and relapse. The acoustic startle response (ASR) is a component of anxiety that has been shown to increase during opioid withdrawal in both humans and animals. We investigated the role of corticotropin-releasing factor (CRF) and norepinephrine (NE), two key mediators of the brain stress system, on acute heroin withdrawal-potentiated ASR. Rats injected with heroin (2 mg/kg s.c.) displayed an increased ASR when tested 4 h after heroin treatment. A similar increase in ASR was found in rats 10-20 h into withdrawal from extended access (12 h) to i.v. heroin self-administration, a model that captures several aspects of heroin addiction in humans. Both the α 2 adrenergic receptor agonist clonidine (10 μg/kg s.c.) and CRF1 receptor antagonist N,N-bis(2-methoxyethyl)-3-(4-methoxy-2-methylphenyl)-2,5-dimethyl-pyrazolo[1,5-a] pyrimidin-7-amine (MPZP; 20 mg/kg s.c.) blocked heroin withdrawal-potentiated startle. To investigate the relationship between CRF1 and α 2 adrenergic receptors in the potentiation of the ASR, we tested the effect of MPZP on yohimbine (1.25 mg/kg s.c.)-potentiated startle and clonidine on CRF (2 μg i.c.v.)-potentiated startle. Clonidine blocked CRF-potentiated startle, whereas MPZP partially attenuated but did not reverse yohimbine-potentiated startle, suggesting that CRF may drive NE release to potentiate startle. These results suggest that CRF1 and α 2 receptors play an important role in the heightened anxiety-like behaviour observed during acute withdrawal from heroin, possibly via CRF inducing the release of NE in stress-related brain regions.

A novel pre-clinical strategy for identifying cardiotoxic kinase inhibitors and mechanisms of cardiotoxicity

PubMed Central

Cheng, Hui; Kari, Gabor; Dicker, Adam P; Rodeck, Ulrich; Koch, Walter J; Force, Thomas

2011-01-01

Rationale 1) Despite intense interest in strategies to predict which kinase inhibitor (KI) cancer therapeutics may be associated with cardiotoxicity, current approaches are inadequate. 2) Sorafenib is a KI of concern since it inhibits growth factor receptors and Raf-1/B-Raf, kinases that are upstream of ERKs and signal cardiomyocyte survival in the setting of stress. Objectives 1) Explore the potential use of zebrafish as a pre-clinical model to predict cardiotoxicity. 2) Determine whether sorafenib has associated cardiotoxicity and, if so, define the mechanisms. Methods and Results We find that the zebrafish model is readily able to discriminate a KI with little or no cardiotoxicity (gefitinib) from one with demonstrated cardiotoxicity (sunitinib). Sorafenib, like sunitinib, leads to cardiomyocyte apoptosis, a reduction in total myocyte number per heart, contractile dysfunction and ventricular dilatation in zebrafish. In cultured rat cardiomyocytes, sorafenib induces cell death. This can be rescued by adenovirus-mediated gene transfer of constitutively active MEK1 which restores ERK activity even in the presence of sorafenib. While growth factor-induced activation of ERKs requires Raf, α-adrenergic agonist-induced activation of ERKs does not. Consequently, activation of α-adrenergic signaling markedly decreases sorafenib-induced cell death. Consistent with these in vitro data, inhibition of α-adrenergic signaling with the receptor antagonist prazosin worsens sorafenib-induced cardiomyopathy in zebrafish. Conclusions 1) Zebrafish may be a valuable pre-clinical tool to predict cardiotoxicity. 2) The α-adrenergic signaling pathway is an important modulator of sorafenib cardiotoxicity in vitro and in vivo and appears to act via a here-to-fore unrecognized signaling pathway downstream of α-adrenergic activation that bypasses Raf to activate ERKs. PMID:21998323

Mixed nicotinic-muscarinic properties of the alpha9 nicotinic cholinergic receptor.

PubMed

Verbitsky, M; Rothlin, C V; Katz, E; Elgoyhen, A B

2000-10-01

The rat alpha9 nicotinic acetylcholine receptor (nAChR) was expressed in Xenopus laevis oocytes and tested for its sensitivity to a wide variety of cholinergic compounds. Acetylcholine (ACh), carbachol, choline and methylcarbachol elicited agonist-evoked currents, giving maximal or near maximal responses. Both the nicotinic agonist suberyldicholine as well as the muscarinic agonists McN-A-343 and methylfurtrethonium behaved as weak partial agonists of the receptor. Most classical cholinergic compounds tested, being either nicotinic (nicotine, epibatidine, cytisine, methyllycaconitine, mecamylamine, dihydro-beta-erythroidine), or muscarinic (muscarine, atropine, gallamine, pilocarpine, bethanechol) agonists and antagonists, blocked the recombinant alpha9 receptor. Block by nicotine, epibatidine, cytisine, methyllycaconitine and atropine was overcome at high ACh concentrations, suggesting a competitive type of block. The present results indicate that alpha9 displays mixed nicotinic-muscarinic features that resemble the ones described for the cholinergic receptor of cochlear outer hair cells (OHCs). We suggest that alpha9 contains the structural determinants responsible for the pharmacological properties of the native receptor.

Central venous pressure and mean circulatory filling pressure in the dogfish Squalus acanthias: adrenergic control and role of the pericardium.

PubMed

Sandblom, Erik; Axelsson, Michael; Farrell, Anthony P

2006-11-01

Subambient central venous pressure (Pven) and modulation of venous return through cardiac suction (vis a fronte) characterizes the venous circulation in sharks. Venous capacitance was estimated in the dogfish Squalus acanthias by measuring the mean circulatory filling pressure (MCFP) during transient occlusion of cardiac outflow. We tested the hypothesis that venous return and cardiac preload can be altered additionally through adrenergic changes of venous capacitance. The experiments involved the surgical opening of the pericardium to place a perivascular occluder around the conus arteriosus. Another control group was identically instrumented, but lacked the occluder, and was subjected to the same pharmacological protocol to evaluate how pericardioectomy affected cardiovascular status. Routine Pven was negative (-0.08+/-0.02 kPa) in control fish but positive (0.09+/-0.01 kPa) in the pericardioectomized group. Injections of 5 microg/kg body mass (Mb) of epinephrine and phenylephrine (100 microg/kg Mb) increased Pven and MCFP, whereas isoproterenol (1 microg/kg Mb) decreased both variables. Thus, constriction and relaxation of the venous vasculature were mediated through the respective stimulation of alpha- and beta-adrenergic receptors. Alpha-adrenergic blockade with prazosin (1 mg/kg Mb) attenuated the responses to phenylephrine and decreased resting Pven in pericardioectomized animals. Our results provide convincing evidence for adrenergic control of the venous vasculature in elasmobranchs, although the pericardium is clearly an important component in the modulation of venous function. Thus active changes in venous capacitance have previously been underestimated as an important means of modulating venous return and cardiac performance in this group.

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

2017-06-01

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 β 3 -adrenergic receptor knockout mice reported that brite/beige adipocytes, but not classical brown adipocytes, require the β 3 -adrenergic receptor for cold-induced transcriptional activation of thermogenic genes. We aimed to further characterize this requirement of the β 3 -adrenergic receptor as a functional distinction between classical brown and brite/beige adipocytes. However, when comparing wild-type and β 3 -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 β 3 -adrenergic receptor. Experiments with the β 3 -adrenergic receptor agonist CL-316,243 verified the functional absence of β 3 -adrenergic signaling in these knockout mice. The β 3 -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 β 3 -adrenergic receptor is dispensable for cold-induced transcriptional activation in both classical brown and, as opposed to earlier studies, brite/beige cells. Copyright © 2017 the American Physiological Society.

Sensitivity of neuronal nicotinic acetylcholine receptors to the opiate antagonists naltrexone and naloxone: receptor blockade and up-regulation.

PubMed

Almeida, Luis E F; Pereira, Edna F R; Camara, Adriana L; Maelicke, Alfred; Albuquerque, Edson X

2004-04-19

In HEK293 cells stably expressing alpha4beta2 nAChRs, naltrexone, but not naloxone, blocked alpha4beta2 nAChRs via an open-channel blocking mechanism. In primary hippocampal cultures, naltrexone inhibited alpha7 nAChRs up-regulated by nicotine, and in organotypic hippocampal cultures naltrexone caused a time-dependent up-regulation of functional alpha7 nAChRs that was detected after removal of the drug. These results indicate that naltrexone could be used as a smoking cessation aid.

Expression of mammalian beta-adrenergic receptors in Xenopus laevis oocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1987-05-01

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

Antinociceptive and Anti-Inflammatory Effects of Octacosanol from the Leaves of Sabicea grisea var. grisea in Mice

PubMed Central

de Oliveira, Anderson Marques; Conserva, Lucia M.; de Souza Ferro, Jamylle N.; de Almeida Brito, Fabíola; Lyra Lemos, Rosângela P.; Barreto, Emiliano

2012-01-01

Sabicea species are used in the Amazon for treatment of fever and malaria, which suggests that its chemical constituents may have some effect on pain and inflammation. Phytochemical analysis of the hexane fraction obtained from the crude ethanol extract from Sabicea grisea var. grisea Cham. & Schltdl (Rubiaceae), an endemic plant in Brazil, resulted in the isolation of octacosanol. This study investigated the antinociceptive and anti-inflammatory effects of the octacosanol in different experimental models. The crude ethanolic extract and hexane fraction obtained from the leaves of S. grisea produced an inhibition of acetic acid-induced pain. Moreover, octacosanol isolated from the hexane fraction produced a significant inhibition of pain response elicited by acetic acid. Pre-treatment with yohimbine, an alpha 2-adrenergic receptor antagonist, notably reversed the antinociceptive activity induced by octacosanol in the abdominal constriction test. Furthermore, mice treated with octacosanol did not exhibit any behavioral alteration during the hot plate and rota-rod tests, indicating non-participation of the supraspinal components in the modulation of pain by octacosanol with no motor abnormality. In the formalin test, octacosanol did not inhibit the licking time in first phase (neurogenic pain), but significantly inhibited the licking time in second phase (inflammatory pain) of mice. The anti-inflammatory effect of octacosanol was evaluated using carrageenan-induced pleurisy. The octacosanol significantly reduced the total leukocyte count and neutrophils influx, as well as TNF-α levels in the carrageenan-induced pleurisy. This study revealed that the mechanism responsible for the antinociceptive and anti-inflammatory effects of the octacosanol appears to be partly associated with an inhibition of alpha 2-adrenergic transmission and an inhibition of pathways dependent on pro-inflammatory cytokines. Finally, these results demonstrated that the octacosanol from the leaves of S. grisea possesses antinociceptive and anti-inflammatory activities, which could be of relevance for the pharmacological control of pain and inflammatory processes. PMID:22408410

Prazosin, an adrenergic blocking agent inadequate as male contraceptive pill.

PubMed

Kjaergaard, N; Kjaergaard, B; Lauritsen, J G

1988-06-01

The purpose of this study was to investigate the efficacy and the acceptability of Prazosin as a male contraceptive pill. Acceptable antifertility drugs for men are proving difficult to produce, and the possibility of using pharmacological agents to block selectively or to inhibit normal sperm transport through the male genital tract is an interesting approach. Prazosin administered in doses up to 10 mg/day did not cause azoospermia following ejaculation. In conclusion, we have not been able to confirm either the efficacy or the acceptability of the alpha 1-adrenoceptor antagonist Prazosin as a male contraceptive drug. Homonnai et al. confirmed the fact that phenoxybenzamine blocks ejaculation, but it should be noted that although both drugs are alpha 1-adrenoceptor blocking agents, they are not chemically identical.

Tumor necrosis factor-alpha antagonists: differential clinical effects by different biotechnological molecules.

PubMed

Licastro, F; Chiappelli, M; Ianni, M; Porcellini, E

2009-01-01

Inhibitors of tumor necrosis factor-alpha have deeply changed the therapy of several inflammatory human diseases. For instance, clinical management of rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis have profoundly benefited after the introduction of new therapeutic tools, such as antagonist of TNF-alpha molecule. These drugs include etanercept, a soluble TNF-alpha receptor antagonist, three anti-TNF-alpha antibodies, adalimumab, infliximab, golimumab and certolizumab a humanized Fab fragment combined with polyethylene glycol. These compounds efficiently inhibit several TNF-alpha biological-mediated effects, however, they have also shown differential clinical efficacy in several trials from different autoimmune diseases. It is of clinical relevance that non-responders to one of these drugs often positively responded to another. Different mechanisms of action and diversity in pharmacokinetics of these three compounds may partially explain different clinical effects. However, partially diverse pathogenetic mechanisms in different diseases also contribute to differential therapeutic responses. Therefore, these apparently homogeneous agents can not be considered equivalent in their clinically efficacy. Differential therapeutic actions of these drugs may be advantageously used in clinical practice and further improve the great potential of individual TNF-alpha inhibitors.

Design and synthesis of novel sulfonamide-containing bradykinin hB2 receptor antagonists. 2. Synthesis and structure-activity relationships of alpha,alpha-cycloalkylglycine sulfonamides.

PubMed

Fattori, Daniela; Rossi, Cristina; Fincham, Christopher I; Caciagli, Valerio; Catrambone, Fernando; D'Andrea, Piero; Felicetti, Patrizia; Gensini, Martina; Marastoni, Elena; Nannicini, Rossano; Paris, Marielle; Terracciano, Rosa; Bressan, Alessandro; Giuliani, Sandro; Maggi, Carlo A; Meini, Stefania; Valenti, Claudio; Quartara, Laura

2007-02-08

Recently we reported on the design and synthesis of a novel class of selective nonpeptide bradykinin (BK) B2 receptor antagonists (J. Med. Chem. 2006, 3602-3613). This work led to the discovery of MEN 15442, an antagonist with subnanomolar affinity for the human B2 receptor (hB2R), which also displayed significant and prolonged activity in vivo (for up to 210 min) against BK-induced bronchoconstriction in the guinea-pig at a dose of 300 nmol/kg (it), while demonstrating only a slight effect on BK-induced hypotension. Here we describe the further optimization of this series of compounds aimed at maximizing the effect on bronchoconstriction and minimizing the effect on hypotension, with a view to developing topically delivered drugs for airway diseases. The work led to the discovery of MEN 16132, a compound which, after intratracheal or aerosol administration, inhibited, in a dose-dependent manner, BK-induced bronchoconstricton in the airways, while showing minimal systemic activity. This compound was selected as a preclinical candidate for the topical treatment of airway diseases involving kinin B2 receptor stimulation.

Synthesis and biological evaluation of new 2-(4,5-dihydro-1H-imidazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine derivatives.

PubMed

Touzeau, Frédérique; Arrault, Axelle; Guillaumet, Gérald; Scalbert, Elizabeth; Pfeiffer, Bruno; Rettori, Marie-Claire; Renard, Pierre; Mérour, Jean-Yves

2003-05-08

2-(4,5-Dihydro-1H-imidazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine derivatives and tricyclic analogues with a fused additional ring on the nitrogen atom of the benzoxazine moiety have been prepared and evaluated for their cardiovascular effects as potential antihypertensive agents. The imidazoline ring was generated by reaction of the corresponding ethyl ester with ethylenediamine. Affinities for imidazoline binding sites (IBS) I(1) and I(2) and alpha(1) and alpha(2) adrenergic receptors were evaluated as well as the effects on mean arterial blood pressure (MAP) and heart rate (HR) of spontaneously hypertensive rats. With few exceptions the most active compounds on MAP were those with high affinities for IBS and alpha(2) receptor. Among these, compound 4h was the most interesting and is now, together with its enantiomers, under complementary pharmacological evaluation.

The anti-hypertensive drug prazosin inhibits glioblastoma growth via the PKCδ-dependent inhibition of the AKT pathway.

PubMed

Assad Kahn, Suzana; Costa, Silvia Lima; Gholamin, Sharareh; Nitta, Ryan T; Dubois, Luiz Gustavo; Fève, Marie; Zeniou, Maria; Coelho, Paulo Lucas Cerqueira; El-Habr, Elias; Cadusseau, Josette; Varlet, Pascale; Mitra, Siddhartha S; Devaux, Bertrand; Kilhoffer, Marie-Claude; Cheshier, Samuel H; Moura-Neto, Vivaldo; Haiech, Jacques; Junier, Marie-Pierre; Chneiweiss, Hervé

2016-05-01

A variety of drugs targeting monoamine receptors are routinely used in human pharmacology. We assessed the effect of these drugs on the viability of tumor-initiating cells isolated from patients with glioblastoma. Among the drugs targeting monoamine receptors, we identified prazosin, an α1- and α2B-adrenergic receptor antagonist, as the most potent inducer of patient-derived glioblastoma-initiating cell death. Prazosin triggered apoptosis of glioblastoma-initiating cells and of their differentiated progeny, inhibited glioblastoma growth in orthotopic xenografts of patient-derived glioblastoma-initiating cells, and increased survival of glioblastoma-bearing mice. We found that prazosin acted in glioblastoma-initiating cells independently from adrenergic receptors. Its off-target activity occurred via a PKCδ-dependent inhibition of the AKT pathway, which resulted in caspase-3 activation. Blockade of PKCδ activation prevented all molecular changes observed in prazosin-treated glioblastoma-initiating cells, as well as prazosin-induced apoptosis. Based on these data, we conclude that prazosin, an FDA-approved drug for the control of hypertension, inhibits glioblastoma growth through a PKCδ-dependent mechanism. These findings open up promising prospects for the use of prazosin as an adjuvant therapy for glioblastoma patients. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

Structure-activity relationships of the melanocortin tetrapeptide Ac-His-DPhe-Arg-Trp-NH(2) at the mouse melanocortin receptors: part 2 modifications at the Phe position.

PubMed

Holder, Jerry Ryan; Bauzo, Rayna M; Xiang, Zhimin; Haskell-Luevano, Carrie

2002-07-04

The melanocortin pathway is an important participant in skin pigmentation, steroidogenesis, obesity, energy homeostasis and exocrine gland function. The centrally located melanocortin-3 and melanocortin-4 receptors (MC3R, MC4R) are involved in the metabolic and food intake aspects of energy homeostasis and are stimulated by melanocortin agonists such as alpha-melanocyte stimulation hormone (alpha-MSH). The melanocortin agonists contain the putative message sequence "His-Phe-Arg-Trp," and it has been well-documented that inversion of chirality of the Phe to DPhe results in a dramatic increase in melanocortin receptor potency. Herein, we report a tetrapeptide library, based upon the template Ac-His-DPhe-Arg-Trp-NH(2), consisting of 26 members that have been modified at the DPhe(7) position (alpha-MSH numbering) and pharmacologically characterized for agonist and antagonist activity at the mouse melanocortin receptors MC1R, MC3R, MC4R, and MC5R. The most notable results of this study include the identification of the tetrapeptide Ac-His-(pI)DPhe-Arg-Trp-NH(2) that is a full nanomolar agonist at the mMC1 and mMC5 receptors, a mMC3R partial agonist with potent antagonist activity (pA(2) = 7.25, K(i) = 56 nM) and, but unexpectedly, is a potent agonist at the mMC4R (EC(50) = 25 nM). This ligand possesses novel melanocortin receptor pharmacology, as compared to previously reported peptides, and is potentially useful for in vivo studies to differentiate MC3R vs MC4R physiological roles in animal models, such as primates, where "knockout" animals are not viable options. The DNal(2') substitution for DPhe resulted in a mMC3R partial agonist with antagonist activity (pA(2) = 6.5, K(i) = 295 nM) and a mMC4R (pA(2) = 7.8, K(i) = 17 nM) antagonist possessing 60- and 425-fold decreased potency, respectively, as compared with SHU9119 at these receptors. Examination of this DNal(2')-containing tetrapeptide at the F254S and F259S mutant mMC4Rs resulted in agonist activity of this mMC4R tetrapeptide antagonist, similar to that observed for the SHU9119 peptide, supporting our previously proposed hypothesis that the Phe 254 and 259 transmembrane six receptor residues are important for differentiating melanocortin sequence-based MC4R antagonists vs the agouti-related protein (AGRP) sequence-based antagonists.

Ionotropic and metabotropic glutamate receptor mediation of glucocorticoid-induced apoptosis in hippocampal cells and the neuroprotective role of synaptic N-methyl-D-aspartate receptors.

PubMed

Lu, J; Goula, D; Sousa, N; Almeida, O F X

2003-01-01

Glutamate receptors have been proposed to mediate the apoptotic actions of glucocorticoids in hippocampal cells. To further analyze the role of glutamate receptors in this process, we pretreated primary hippocampal cells from neonatal (postnatal day 4) rats with antagonists of ionotropic glutamate receptor (iGluR) and metabotropic glutamate receptor (mGluR) antagonists before exposure to the specific glucocorticoid receptor agonist dexamethasone (DEX) at a dose of 1 microM. Dizocilpine (MK801; a general N-methyl-D-aspartic acid [NMDA] receptor antagonist, NMDAR antagonist) and ifenprodil (a specific ligand of the NMDAR 2B subunit, NR2B), were used to block iGluR; (RS)-alpha-ethyl-4-carboxyphenylglycine (E4CPG) and (RS)-alpha-cyclopropyl-4-phosphonophenyl-glycine (CPPG) were employed as I/II (E4CPG) and II/III (CPPG) mGluR antagonists. Blockade of iGluR resulted in a significant attenuation of DEX-induced cell death; the finding that ifenprodil exerted a similar potency to MK801 demonstrates the involvement of NR2B receptors in glucocorticoid-induced cell death. Apoptosis accounted for a significant amount of the cell loss observed, as detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling histochemistry for the in situ labeling of DNA breaks; apoptotic cells were distinguished from necrosis on the basis of morphological criteria, including chromatin condensation, membrane blebbing and presence of apoptotic bodies. Treatment with E4CPG and CPPG completely abolished the apoptotic response to DEX, thus showing the additional contribution of mGluR to the phenomenon. Further, dose-response studies with NMDA revealed that whereas high (10 microM) doses of NMDA themselves elicit cytotoxic responses, low (1-5 microM) concentrations of NMDA can effectively oppose DEX-induced cell death. Interestingly, the neuroprotective actions of low dose NMDA stimulation were abolished when either synaptic or extrasynaptic NMDA receptors were blocked with MK801 in combination with the GABA receptor antagonist bicuculline (synaptic) or ifenprodil (extrasynaptic). In summary, the present data show that both iGluR and mGluR mediate the neurotoxic effects of glucocorticoids on hippocampal cells and that pre-treatment with low doses of NMDA, by acting on synaptic and extrasynaptic receptors, render hippocampal cells less vulnerable to glucocorticoid insults.

From Chemotherapy-Induced Emesis to Neuroprotection: Therapeutic Opportunities for 5-HT3 Receptor Antagonists.

PubMed

Fakhfouri, Gohar; Mousavizadeh, Kazem; Mehr, Sharam Ejtemaei; Dehpour, Ahmad Reza; Zirak, Mohammad Reza; Ghia, Jean-Eric; Rahimian, Reza

2015-12-01

5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to Aβ-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-α level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against Aβ-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-κB, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications.

Diadenosine tetraphosphate improves adrenergic anti-glaucomatous drug delivery and efficiency.

PubMed

Loma, Patricia; Guzman-Aranguez, Ana; Perez de Lara, Maria Jesus; Pintor, Jesus

2015-05-01

The effect of the dinucleotide P(1), P(4)-Di (adenosine-5') tetraphosphate (Ap4A) in improving adrenergic anti-glaucomatous delivery by modifying the tight junction proteins of the corneal epithelium was evaluated. Stratified human corneal epithelial cells (HCLE) were treated with Ap4A (100 μM) for 5 min and TJ protein levels and barrier function were analysed by western blotting and transepithelial electrical resistance (TEER), respectively. Western blot experiments showed a significant reduction at 2 h (45% reduction of ZO-1 and 65% reduction of occludin protein levels) as compared to non-treated (control) cells. Two hours after Ap4A treatment, TEER values were significantly reduced (65% as compared to control levels (p < 0.001)), indicating an increase in corneal barrier permeability. Topical application of Ap4A in New Zealand white rabbits two hours before the instillation of the hypotensor compounds (the α2-adrenergic receptor agonist, brimonidine and the β-adrenergic receptor antagonist, timolol), improved the delivery of these compounds to the anterior chamber as well as their hypotensive action on the intraocular pressure. The results obtained showed that, when Ap4A was topically applied two hours before the adrenergic compounds, the concentration of brimonidine in the aqueous humour increased from 64.3 ± 5.3 nM to 240.6 ± 8.6 nM and from 58.9 ± 9.2 nM to 183.7 ± 6.8 nM in the case of timolol, which also produces a more profound effect on IOP. Therefore, Ap4A treatment results in a better entrance of adrenergic anti-glaucomatous compounds within the eye and consequently improved therapeutic efficiency by increasing corneal epithelial barrier permeability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Raynaud's phenomenon and digital ischaemia--pharmacologic approach and alternative treatment options.

PubMed

Linnemann, Birgit; Erbe, Matthias

2016-01-01

The primary goal of therapy is to reduce the frequency and intensity of Raynaud's attacks and to minimize the related morbidity rather than to cure the underlying condition. Treatment strategies depend on whether Raynaud's phenomenon (RP) is primary or secondary. All patients should be instructed about general measures to maintain body warmth and to avoid triggers of RP attacks. Pharmacologic intervention can be useful for patients with severe and frequent RP episodes that impair the patient's quality of life. Calcium channel blockers are currently the most prescribed and studied medications for this purpose. There has been limited evidence for the efficacy of alpha-1-adrenergic receptor antagonists, angiotensin receptor blockers, topical nitrates or fluoxetine to treat RP. The intravenously administered prostacyclin analogue iloprost can reduce the frequency and severity of RP attacks and is considered a second-line therapy in patients with markedly impaired quality of life, critical digital ischaemia and skin ulcers who are at risk for substantial tissue loss and amputation. Phosphodiesterase inhibitors (e.g., sildenafil) can also improve RP symptoms and ulcer healing whereas endothelin-1 receptor antagonists (e.g., bosentan) are mainly considered treatment options in secondary prevention for patients with digital skin ulcers related to systemic sclerosis. However, their use in clinical practice has been limited by their high cost. Antiplatelet therapy with low-dose aspirin is recommended for all patients who suffer from secondary RP due to ischaemia caused by structural vessel damage. Anticoagulant therapy can be considered during the acute phase of digital ischaemia in patients with suspected vascular occlusive disease attributed to the occurrence of new thromboses. In patients with critical digital ischaemia, consideration should be given to hospitalisation, optimisation of medical treatment in accordance with the underlying disease and evaluation for a secondary, possibly reversible process that is causing or aggravating the clinical symptoms.

Modulation of the release of ( sup 3 H)norepinephrine from the base and body of the rat urinary bladder by endogenous adrenergic and cholinergic mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Somogyi, G.T.; de Groat, W.C.

Modulation of (3H)NE release was studied in rat urinary bladder strips prelabeled with (3H)NE. (3H)NE uptake occurred in strips from the bladder base and body, but was very prominent in the base where the noradrenergic innervation is most dense. Electrical field stimulation markedly increased (3H)NE outflow from the superfused tissue. The quantity of (3H)NE release was approximately equal during three consecutive periods of stimulation. Activation of presynaptic muscarinic receptors by 1.0 microM oxotremorine reduced (3H)NE release to 46% of the control. Atropine (1 microM) blocked the effect of oxotremorine and increased the release to 147% of predrug control levels. Activationmore » of presynaptic alpha-2 adrenoceptors by 1 microM clonidine reduced (3H)NE release to 55% of control. Yohimbine blocked the action of clonidine and increased the release to 148% of control. The release of (3H)NE from the bladder base and body was increased by both 1 microM atropine (to 167% and 174% of control, respectively) and 1 microM yohimbine (to 286% and 425% of control, respectively). Atropine and yohimbine administered in combination had similar facilitatory effects as when administered alone. We conclude that the release of (3H)NE from adrenergic nerve endings in electrically stimulated bladder strips is modulated via endogenous transmitters acting on both muscarinic and alpha-2 adrenergic presynaptic receptors and that the latter provide the most prominent control.« less

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, suggesting that methylation loss might be due to oxidative stress-induced DNA damage. PMID:24885710

Beta-adrenergic receptor sensitivity, autonomic balance and serotonergic activity in practitioners of Transcendental Meditation

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 skinmore » 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.« less

Solution conformation of a neuronal nicotinic acetylcholine receptor antagonist {alpha}-conotoxin OmIA that discriminates {alpha}3 vs. {alpha}6 nAChR subtypes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Seung-Wook; Kim, Do-Hyoung; Olivera, Baldomero M.

2006-06-23

{alpha}-Conotoxin OmIA from Conus omaria is the only {alpha}-conotoxin that shows a {approx}20-fold higher affinity to the {alpha}3{beta}2 over the {alpha}6{beta}2 subtype of nicotinic acetylcholine receptor. We have determined a three-dimensional structure of {alpha}-conotoxin OmIA by nuclear magnetic resonance spectroscopy. {alpha}-Conotoxin OmIA has an '{omega}-shaped' overall topology with His{sup 5}-Asn{sup 12} forming an {alpha}-helix. Structural features of {alpha}-conotoxin OmIA responsible for its selectivity are suggested by comparing its surface characteristics with other functionally related {alpha}4/7 subfamily conotoxins. Reduced size of the hydrophilic area in {alpha}-conotoxin OmIA seems to be associated with the reduced affinity towards the {alpha}6{beta}2 nAChR subtype.

Alpha-1 adrenergic antagonists, 5-alpha reductase inhibitors, phosphodiesterase type 5 inhibitors, and phytotherapic compounds in men with lower urinary tract symptoms suggestive of benign prostatic obstruction: A systematic review and meta-analysis of urodynamic studies.

PubMed

Fusco, Ferdinando; Creta, Massimiliano; De Nunzio, Cosimo; Gacci, Mauro; Li Marzi, Vincenzo; Finazzi Agrò, Enrico

2018-03-31

To perform a systematic review and meta-analysis of studies evaluating the urodynamic outcomes of alpha-1 adrenergic antagonists (ABs), 5-alpha reductase inhibitors (5-ARIs), phosphodiesterase type 5 inhibitors (PDE5is), and phytotherapic compounds in patients with lower urinary tract symptoms related to benign prostatic obstruction (LUTS/BPO). A systematic review of PubMed/Medline, ISI Web of Knowledge, and Scopus databases was performed in June 2017. We included full papers that met the following criteria: original research; English language; human studies; enrolling LUTS/BPO patients; reporting maximum urinary flow (Qmax), and detrusor pressure at maximum urinary flow (PdetQmax). The primary endpoint was variation in bladder outlet obstruction index (BOOI). Secondary endpoints were variations in Qmax and PdetQmax. Twenty-three studies involving 1044 patients were included in the final analysis. Eighteen, three, two, and one study evaluated the urodynamic outcomes of ABs, 5-ARIs, PDE5is, and phytotherapic compounds, respectively. BOOI, PdetQmax, and Qmax improved in a statistically significant manner in patients receiving ABs and in those receiving 5-ARIs. The overall pooled data showed a mean BOOI change of -15.40 (P < 0.00001) and of -10.55 (P = 0,004) for ABs and 5-ARIs, respectively. Mean PdetQmax and Qmax changes were:12.30 cm H 2 O (P < 0.00001) and +2.27 ml/s (P < 0.00001) for ABs and -9.63 cm H 2 O (P = 0.05), and +1.18 mL/s (P = 0.04) for 5-ARIs. PDE5is and phytotherapic compounds had no significant effects on urodynamic parameters. ABs and 5-ARIs efficiently improve BOOI in men with LUTS/BPO. Both treatments are associated with a clinically significant decrease in PdetQmax but only marginal improvements in Qmax. © 2018 Wiley Periodicals, Inc.

[(35)S]-GTPgammaS autoradiography reveals alpha(2) adrenoceptor-mediated G-protein activation in amygdala and lateral septum.

PubMed

Newman-Tancredi, A; Chaput, C; Touzard, M; Millan, M J

2000-04-03

alpha(2)-adrenoceptor-mediated G-protein activation was examined by [(35)S]-GTPgammaS autoradiography. In alpha(2)-adrenoceptor-rich regions (amygdala, lateral septum), noradrenaline stimulated [(35)S]-GTPgammaS binding. These actions were abolished by the selective alpha(2) antagonist, atipamezole. Conversely, in caudate nucleus, which expresses few alpha(2) receptors, noradrenaline-induced stimulation was not inhibited by atipamezole, suggesting that it is not mediated by alpha(2)-adrenoceptors.

Modeling beta-adrenergic control of cardiac myocyte contractility in silico.

PubMed

Saucerman, Jeffrey J; Brunton, Laurence L; Michailova, Anushka P; McCulloch, Andrew D

2003-11-28

The beta-adrenergic signaling pathway regulates cardiac myocyte contractility through a combination of feedforward and feedback mechanisms. We used systems analysis to investigate how the components and topology of this signaling network permit neurohormonal control of excitation-contraction coupling in the rat ventricular myocyte. A kinetic model integrating beta-adrenergic signaling with excitation-contraction coupling was formulated, and each subsystem was validated with independent biochemical and physiological measurements. Model analysis was used to investigate quantitatively the effects of specific molecular perturbations. 3-Fold overexpression of adenylyl cyclase in the model allowed an 85% higher rate of cyclic AMP synthesis than an equivalent overexpression of beta 1-adrenergic receptor, and manipulating the affinity of Gs alpha for adenylyl cyclase was a more potent regulator of cyclic AMP production. The model predicted that less than 40% of adenylyl cyclase molecules may be stimulated under maximal receptor activation, and an experimental protocol is suggested for validating this prediction. The model also predicted that the endogenous heat-stable protein kinase inhibitor may enhance basal cyclic AMP buffering by 68% and increasing the apparent Hill coefficient of protein kinase A activation from 1.0 to 2.0. Finally, phosphorylation of the L-type calcium channel and phospholamban were found sufficient to predict the dominant changes in myocyte contractility, including a 2.6x increase in systolic calcium (inotropy) and a 28% decrease in calcium half-relaxation time (lusitropy). By performing systems analysis, the consequences of molecular perturbations in the beta-adrenergic signaling network may be understood within the context of integrative cellular physiology.

Modeling beta-adrenergic control of cardiac myocyte contractility in silico

NASA Technical Reports Server (NTRS)

Saucerman, Jeffrey J.; Brunton, Laurence L.; Michailova, Anushka P.; McCulloch, Andrew D.; McCullough, A. D. (Principal Investigator)

2003-01-01

The beta-adrenergic signaling pathway regulates cardiac myocyte contractility through a combination of feedforward and feedback mechanisms. We used systems analysis to investigate how the components and topology of this signaling network permit neurohormonal control of excitation-contraction coupling in the rat ventricular myocyte. A kinetic model integrating beta-adrenergic signaling with excitation-contraction coupling was formulated, and each subsystem was validated with independent biochemical and physiological measurements. Model analysis was used to investigate quantitatively the effects of specific molecular perturbations. 3-Fold overexpression of adenylyl cyclase in the model allowed an 85% higher rate of cyclic AMP synthesis than an equivalent overexpression of beta 1-adrenergic receptor, and manipulating the affinity of Gs alpha for adenylyl cyclase was a more potent regulator of cyclic AMP production. The model predicted that less than 40% of adenylyl cyclase molecules may be stimulated under maximal receptor activation, and an experimental protocol is suggested for validating this prediction. The model also predicted that the endogenous heat-stable protein kinase inhibitor may enhance basal cyclic AMP buffering by 68% and increasing the apparent Hill coefficient of protein kinase A activation from 1.0 to 2.0. Finally, phosphorylation of the L-type calcium channel and phospholamban were found sufficient to predict the dominant changes in myocyte contractility, including a 2.6x increase in systolic calcium (inotropy) and a 28% decrease in calcium half-relaxation time (lusitropy). By performing systems analysis, the consequences of molecular perturbations in the beta-adrenergic signaling network may be understood within the context of integrative cellular physiology.

Spinal 5-HT2 and 5-HT3 receptors mediate low, but not high, frequency TENS-induced antihyperalgesia in rats

PubMed Central

Radhakrishnan, Rajan; King, Ellen W.; Dickman, Janelle K.; Herold, Carli A.; Johnston, Natalie F.; Spurgin, Megan L.; Sluka, Kathleen A.

2009-01-01

Transcutaneous electrical nerve stimulation (TENS) is a form of non-pharmacological treatment for pain. Involvement of descending inhibitory systems is implicated in TENS-induced analgesia. In the present study, the roles of spinal 5-HT and α2-adrenoceptors in TENS analgesia were investigated in rats. Hyperalgesia was induced by inflaming the knee joint with 3% kaolin—carrageenan mixture and assessed by measuring paw withdrawal latency (PWL) to heat before and 4 h after injection. The (1) α2-adrenergic antagonist yohimbine (30 μg), (2) 5-HT antagonist methysergide (5-HT1 and 5-HT2,30 μg), one of the 5-HT receptor subtype antagonists, (3) NAN-190 (5-HT1A, 15 μg), (4) ketanserin (5-HT2A, 30 μg), (5) MDL-72222 (5-HT3, 12 μg), or (6) vehicle was administered intrathecally prior to TENS treatment. Low (4 Hz) or high (100 Hz) frequency TENS at sensory intensity was then applied to the inflamed knee for 20 min and PWL was determined. Selectivity of the antagonists used was confirmed using respective agonists administered intrathecally. Yohimbine had no effect on the antihyperalgesia produced by low or high frequency TENS. Methysergide and MDL-72222 prevented the antihyperalgesia produced by low, but not high, frequency TENS. Ketanserin attenuated the antihyperalgesic effects of low frequency TENS whereas NAN-190 had no effect. The results from the present study show that spinal 5-HT receptors mediate low, but not high, frequency TENS-induced antihyperalgesia through activation of 5-HT2A and 5-HT3 receptors in rats. Furthermore, spinal noradrenergic receptors are not involved in either low or high frequency TENS antihyperalgesia. PMID:14499437

Beta Adrenergic Signaling: A Targetable Regulator of Angiosarcoma and Hemangiosarcoma

PubMed Central

Dickerson, Erin B.; Bryan, Brad A.

2015-01-01

Human angiosarcomas and canine hemangiosarcomas are highly aggressive cancers thought to arise from cells of vascular origin. The pathological features, morphological organization, and clinical behavior of canine hemangiosarcomas are virtually indistinct from those of human angiosarcomas. Overall survival with current standard-of-care approaches remains dismal for both humans and dogs, and each is likely to succumb to their disease within a short duration. While angiosarcomas in humans are extremely rare, limiting their study and treatment options, canine hemangiosarcomas occur frequently. Therefore, studies of these sarcomas in dogs can be used to advance treatment approaches for both patient groups. Emerging data suggest that angiosarcomas and hemangiosarcomas utilize beta adrenergic signaling to drive their progression by regulating the tumor cell niche and fine-tuning cellular responses within the tumor microenvironment. These discoveries indicate that inhibition of beta adrenergic signaling could serve as an Achilles heel for these tumors and emphasize the need to design therapeutic strategies that target tumor cell and stromal cell constituents. In this review, we summarize recent discoveries and present new hypotheses regarding the roles of beta adrenergic signaling in angiosarcomas and hemangiosarcomas. Because the use of beta adrenergic receptor antagonists is well established in human and veterinary medicine, beta blockade could provide an immediate adjunct therapy for treatment along with a tangible opportunity to improve upon the outcomes of both humans and dogs with these diseases. PMID:29061946

Antinociceptive activity of methanolic extract of Muntingia calabura leaves: further elucidation of the possible mechanisms.

PubMed

Zakaria, Zainul Amiruddin; Mohd Sani, Mohd Hijaz; Cheema, Manraj Singh; Kader, Arifah Abdul; Kek, Teh Lay; Salleh, Mohd Zaki

2014-02-20

Muntingia calabura (Elaecoparceae) is a medicinal plant traditionally used, particularly, by the Peruvian people to alleviate headache and cold, pain associated with gastric ulcers or to reduce the prostate gland swelling. Following the recent establishment of antinociceptive activity of M. calabura leaf, the present study was performed to further elucidate on the possible mechanisms of antinociception involved. The methanol extract of M. calabura (MEMC) was prepared in the doses of 100, 250 and 500 mg/kg. The role of bradykinin, protein kinase C, pottasium channels, and various opioid and non-opioid receptors in modulating the extract's antinociceptive activity was determined using several antinociceptive assays. Results are presented as Mean ± standard error of mean (SEM). The one-way ANOVA test with Dunnett's multiple comparison was used to analyze and compare the data, with P < 0.05 as the limit of significance. The MEMC, at all doses, demonstrated a significant (p < 0.05) dose-dependent antinociceptive activity in both the bradykinin- and phorbol 12-myristate 13-acetate (PMA)-induced nociception. Pretreatment of the 500 mg/kg MEMC with 10 mg/kg glibenclamide (an ATP-sensitive K+ channel inhibitor), the antagonist of μ-, δ- and κ-opioid receptors (namely 10 mg/kg β-funaltrexamine, 1 mg/kg naltrindole and 1 mg/kg nor-binaltorphimine), and the non-opioid receptor antagonists (namely 3 mg/kg caffeine (a non-selective adenosinergic receptor antagonist), 0.15 mg/kg yohimbine (an α2-noradrenergic antagonist), and 1 mg/kg pindolol (a β-adrenoceptor antagonist)) significantly (p < 0.05) reversed the MEMC antinociception. However, 10 mg/kg atropine (a non-selective cholinergic receptor antagonist), 0.15 mg/kg prazosin (an α1-noradrenergic antagonist) and 20 mg/kg haloperidol (a non-selective dopaminergic antagonist) did not affect the extract's antinociception. The phytochemicals screening revealed the presence of saponins, flavonoids, tannins and triterpenes while the HPLC analysis showed the presence of flavonoid-based compounds. The antinociceptive activity of MEMC involved activation of the non-selective opioid (particularly the μ-, δ- and κ-opioid) and non-opioid (particularly adenosinergic, α2-noradrenergic, and β-adrenergic) receptors, modulation of the ATP-sensitive K+ channel, and inhibition of bradikinin and protein kinase C actions. The discrepancies in MEMC antinociception could be due to the presence of various phytochemicals.

Beta-lactam antibiotic-induced platelet dysfunction: Evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burroughs, S.F.; Johnson, G.J.

beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of (14C)-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; butmore » no irreversible inhibition of alpha 2 adrenergic receptors, measured with (3H)-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist (3H)-U46619 and antagonist (3H)-SQ29548, occurred. However, low-affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ((Ca2+)i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in (Ca2+)i. The loss of low-affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane.« less

Alpha-2 adrenoceptors and imidazoline receptors in cardiomyocytes mediate counterbalancing effect of agmatine on NO synthesis and intracellular calcium handling.

PubMed

Maltsev, Alexander V; Kokoz, Yuri M; Evdokimovskii, Edward V; Pimenov, Oleg Y; Reyes, Santiago; Alekseev, Alexey E

2014-03-01

Evidence suggests that intracellular Ca(2+) levels and contractility of cardiomyocytes can be modulated by targeting receptors other than already identified adrenergic or non-adrenergic sarcolemmal receptors. This study uncovers the presence in myocardial cells of adrenergic α2 (α2-AR) and imidazoline I1 (I1R) receptors. In isolated left ventricular myocytes generating stationary spontaneous Ca(2+) transients in the absence of triggered action potentials, the prototypic agonist of both receptors agmatine can activate corresponding signaling cascades with opposing outcomes on nitric oxide (NO) synthesis and intracellular Ca(2+) handling. Specifically, activation of α2-AR signaling through PI3 kinase and Akt/protein kinase B stimulates NO production and abolishes Ca(2+) transients, while targeting of I1R signaling via phosphatidylcholine-specific phospholipase C (PC-PLC) and protein kinase C (PKC) suppresses NO synthesis and elevates averaged intracellular Ca(2+). We identified that endothelial NO synthase (eNOS) is a major effector for both signaling cascades. According to the established eNOS transitions between active (Akt-dependent) and inactive (PKC-dependent) conformations, we suggest that balance between α2-AR and I1R signaling pathways sets eNOS activity, which by defining operational states of myocellular sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) can adjust Ca(2+) re-uptake and thereby cardiac inotropy. These results indicate that the conventional catalog of cardiomyocyte sarcolemmal receptors should be expanded by the α2-AR and I1R populations, unveiling previously unrecognized targets for endogenous ligands as well as for existing and potential pharmacological agents in cardiovascular medicine. Copyright © 2014 Elsevier Ltd. All rights reserved.

Topiramate in opiate withdrawal.

PubMed

Zullino, Daniele F; Cottier, Anne-Claude; Besson, Jacques

2002-10-01

The alpha2-adrenergic agonist clonidine is the mainly used drug for the opiate withdrawal. Its efficacy and tolerance in treating withdrawal symptoms is, however, suboptimal. The pharmacological profile of topiramate suggests it could be rather valuable for opiate withdrawal, as there is some evidence that topiramate acts, among others, through inhibition of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors, which play an important role in the withdrawal-induced activation of the locus coeruleus (LC) by glutamate. Three patients undergoing an inpatient opiate detoxification program were treated with topiramate, which achieved a nearly complete control of withdrawal symptoms.

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

PubMed

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

2016-09-01

To date, the study of the sympathetic regulation of renal function has been restricted to the important contribution of β1- and β2-adrenergic receptors (ARs). Here we investigate the expression and the possible physiologic role of β3-adrenergic receptor (β3-AR) in mouse kidney. The β3-AR is expressed in most of the nephron segments that also express the type 2 vasopressin receptor (AVPR2), including the thick ascending limb and the cortical and outer medullary collecting duct. Ex vivo experiments in mouse kidney tubules showed that β3-AR stimulation with the selective agonist BRL37344 increased intracellular cAMP levels and promoted 2 key processes in the urine concentrating mechanism. These are accumulation of the water channel aquaporin 2 at the apical plasma membrane in the collecting duct and activation of the Na-K-2Cl symporter in the thick ascending limb. Both effects were prevented by the β3-AR antagonist L748,337 or by the protein kinase A inhibitor H89. Interestingly, genetic inactivation of β3-AR in mice was associated with significantly increased urine excretion of water, sodium, potassium, and chloride. Stimulation of β3-AR significantly reduced urine excretion of water and the same electrolytes. Moreover, BRL37344 promoted a potent antidiuretic effect in AVPR2-null mice. Thus, our findings are of potential physiologic importance as they uncover the antidiuretic effect of β3-AR stimulation in the kidney. Hence, β3-AR agonism might be useful to bypass AVPR2-inactivating mutations. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Involvement of β3-adrenergic receptors in the control of food intake in rats.

PubMed

Kanzler, S A; Januario, A C; Paschoalini, M A

2011-11-01

This study examined the food intake changes evoked by intracerebroventricular (icv) injection of a selective agonist (BRL37344, 2 and 20 nmol) or antagonist (SR59230A, 10 and 50 nmol) of β3-adrenergic receptors in 24-h fasted rats (adult male Wistar rats, 200-350 g, N = 6/treatment). The animals were also pretreated with saline icv (SAL) or SR59230A (50 nmol) followed by BRL37344 (20 nmol) or SAL in order to determine the selectivity of the effects evoked by BRL37344 on food intake or the selectivity of the effects evoked by SR59230A on risk assessment (RA) behavior. The highest dose of BRL37344 (N = 7) decreased food intake 1 h after the treatment (6.4 ± 0.5 g in SAL-treated vs 4.2 ± 0.8 g in drug-treated rats). While both doses of SR59230A failed to affect food intake (5.1 ± 1.1 g for 10 nmol and 6.0 ± 1.8 g for 50 nmol), this treatment reduced the RA frequency (number/30 min) (4 ± 2 for SAL-treated vs 1 ± 1 for 10 nmol and 0.5 ± 1 for 50 nmol SR59230A-treated rats), an ethological parameter related to anxiety. While pretreatment with SR59230A (7.0 ± 0.5 g) abolished the hypophagia induced by BRL37344 (3.6 ± 0.9 g), BRL37344 suppressed the reduction in RA frequency caused by SR59230A. These results show that the hypophagia caused by BRL37344 is selectively mediated by β3-adrenergic receptors within the central nervous system. Moreover, they suggest the involvement of these receptors in the control of anxiety.

Crosstalk Between Adrenergic and Toll-Like Receptors in Human Mesenchymal Stem Cells and Keratinocytes: A Recipe for Impaired Wound Healing

PubMed Central

Ramirez, Sandra R.; La, Thi Dinh; Gorouhi, Farzam; Nguyen, Chuong; Lin, Benjamin R.; Mashburn, Chelcy; Stewart, Heather; Peavy, Thomas R.; Nolta, Jan A.

2014-01-01

Previous studies demonstrate that skin wounds generate epinephrine (EPI) that can activate local adrenergic receptors (ARs), impairing healing. Bacterially derived activators of Toll-like receptors (TLRs) within the wound initiate inflammatory responses and can also impair healing. In this study, we examined the hypothesis that these two pathways crosstalk to one another, using EPI and macrophage-activating lipopeptide-2 (MALP2) to activate ARs and TLR2, respectively, in human bone marrow-derived mesenchymal stem cells (BM-MSCs) and neonatal keratinocytes (NHKs). BM-MSCs exposed to EPI significantly (p < .05) increased TLR2 message (sevenfold BM-MSCs), TLR2 protein (twofold), and myeloid differentiation factor 88 (MyD88) (fourfold). Conversely, activation of TLR2 by MALP2 in these cells increased β2-AR message (twofold in BM-MSCs, 2.7-fold in NHKs), β2-AR protein (2.5-fold), phosphorylation of β-AR-activated kinase (p-BARK, twofold), and induced release of EPI from both cell types (twofold). Treating cells with EPI and MALP2 together, as would be encountered in a wound, increased β2-AR and p-BARK protein expression (sixfold), impaired cell migration (BM-MSCs- 21%↓ and NHKs- 60%↓, p < .002), and resulted in a 10-fold (BM-MSCs) and 51-fold (NHKs) increase in release of IL-6 (p < .001) responses that were remarkably reduced by pretreatment with β2-AR antagonists. In vivo, EPI-stressed animals exhibited impaired healing, with elevated levels of TLR2, MyD88, and IL-6 in the wounds (p < .05) relative to nonstressed controls. Thus, our data describe a recipe for decreasing cell migration and exacerbating inflammation via novel crosstalk between the adrenergic and Toll-like receptor pathways in BM-MSCs and NHKs. PMID:24760207

Impact of the canine double-deletion β1 adrenoreceptor polymorphisms on protein structure and heart rate response to atenolol, a β1-selective β-blocker.

PubMed

Meurs, Kathryn M; Stern, Josh A; Reina-Doreste, Yamir; Maran, Brian A; Chdid, Lhoucine; Lahmers, Sunshine; Keene, Bruce W; Mealey, Katrina L

2015-09-01

β-Adrenergic receptor antagonists are widely utilized for the management of cardiac diseases in dogs. We have recently identified two deletion polymorphisms in the canine adrenoreceptor 1 (ADRB1) gene.We hypothesized that canine ADRB1 deletions would alter the structure of the protein, as well as the heart rate response to the β-adrenergic receptor antagonist, atenolol. The objectives of this study were to predict the impact of these deletions on the predicted structure of the protein and on the heart rate response to atenolol in a population of healthy adult dogs. Eighteen apparently healthy, mature dogs with (11) and without (seven) ADRB1 deletions were evaluated. The heart rate of the dogs was evaluated with a baseline ambulatory ECG before and 14-21 days after atenolol therapy (1 mg/kg orally q12 h). Minimum, average, and maximum heart rates were compared between groups of dogs (deletions, controls) using an unpaired t-test and within each group of dogs using a paired t-test. The protein structure of ADRB1 was predicted by computer modeling. Deletions were predicted to alter the structure of the ADRB1 protein. The heart rates of the dogs with deletions were lower than those of the control dogs (the average heart rates were significantly lower). ADRB1 deletions appear to have structural and functional consequences. Individual genome-based treatment recommendations could impact the management of dogs with heart disease.

Multitarget-directed tricyclic pyridazinones as G protein-coupled receptor ligands and cholinesterase inhibitors.

PubMed

Pau, Amedeo; Catto, Marco; Pinna, Giovanni; Frau, Simona; Murineddu, Gabriele; Asproni, Battistina; Curzu, Maria M; Pisani, Leonardo; Leonetti, Francesco; Loza, Maria Isabel; Brea, José; Pinna, Gérard A; Carotti, Angelo

2015-06-01

By following a multitarget ligand design approach, a library of 47 compounds was prepared, and they were tested as binders of selected G protein-coupled receptors (GPCRs) and inhibitors of acetyl and/or butyryl cholinesterase. The newly designed ligands feature pyridazinone-based tricyclic scaffolds connected through alkyl chains of variable length to proper amine moieties (e.g., substituted piperazines or piperidines) for GPCR and cholinesterase (ChE) molecular recognition. The compounds were tested at three different GPCRs, namely serotoninergic 5-HT1A, adrenergic α1A, and dopaminergic D2 receptors. Our main goal was the discovery of compounds that exhibit, in addition to ChE inhibition, antagonist activity at 5-HT1A because of its involvement in neuronal deficits typical of Alzheimer's and other neurodegenerative diseases. Ligands with nanomolar affinity for the tested GPCRs were discovered, but most of them behaved as dual antagonists of α1A and 5-HT1A receptors. Nevertheless, several compounds displaying this GPCR affinity profile also showed moderate to good inhibition of AChE and BChE, thus deserving further investigations to exploit the therapeutic potential of such unusual biological profiles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

AHR-16303B, a novel antagonist of 5-HT2 receptors and voltage-sensitive calcium channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, R.J.; Appell, K.C.; Kilpatrick, B.F.

1991-01-01

In vivo and in vitro methods were used to characterize AHR-16303B, a novel compound with antagonistic action at 5-HT2 receptors and voltage-sensitive calcium channels. The 5-HT2 receptor-antagonistic properties of AHR-16303B were demonstrated by inhibition of (a) (3H)ketanserin binding to rat cerebral cortical membranes (IC50 = 165 nM); (b) 5-hydroxytryptamine (5-HT)-induced foot edema in rats (minimum effective dose, (MED) = 0.32 mg/kg orally, p.o.); (c) 5-HT-induced vasopressor responses in spontaneously hypertensive rats (SHR) (ID50 = 0.18 mg/kg intravenously (i.v.), 1.8 mg/kg p.o.), (d) 5-HT-induced antidiuresis in rats (MED = 1 mg/kg p.o.), and (e) platelet aggregation induced by 5-HT + ADPmore » (IC50 = 1.5 mM). The calcium antagonist properties of AHR-16303B were demonstrated by inhibition of (a) (3H)nimodipine binding to voltage-sensitive calcium channels on rabbit skeletal muscle membranes (IC50 = 15 nM), (b) KCl-stimulated calcium flux into cultured PC12 cells (IC50 = 81 nM), and (c) CaCl2-induced contractions of rabbit thoracic aortic strips (pA2 = 8.84). AHR-16303B had little or no effect on binding of radioligands to dopamine2 (DA2) alpha 1, alpha 2, H1, 5-HT1 alpha, beta 2, muscarinic M1, or sigma opioid receptors; had no effect on 5-HT3 receptor-mediated vagal bradycardia; and had only minor negative inotropic, chronotropic, and dromotropic effects on isolated guinea pig atria. In conscious SHR, 30 mg/kg p.o. AHR-16303B completely prevented the vasopressor responses to i.v. 5-HT, and decreased blood pressure (BP) by 24% 3 h after dosing.« less

Molecular recognition at adenine nucleotide (P2) receptors in platelets.

PubMed

Jacobson, Kenneth A; Mamedova, Liaman; Joshi, Bhalchandra V; Besada, Pedro; Costanzi, Stefano

2005-04-01

Transmembrane signaling through P2Y receptors for extracellular nucleotides controls a diverse array of cellular processes, including thrombosis. Selective agonists and antagonists of the two P2Y receptors present on the platelet surface-the G (q)-coupled P2Y (1) subtype and the G (i)-coupled P2Y (12) subtype-are now known. High-affinity antagonists of each have been developed from nucleotide structures. The (N)-methanocarba bisphosphate derivatives MRS2279 and MRS2500 are potent and selective P2Y (1) receptor antagonists. The carbocyclic nucleoside AZD6140 is an uncharged, orally active P2Y (12) receptor antagonist of nM affinity. Another nucleotide receptor on the platelet surface, the P2X (1) receptor, the activation of which may also be proaggregatory, especially under conditions of high shear stress, has high-affinity ligands, although high selectivity has not yet been achieved. Although alpha,beta-methylene-adenosine triphosphate (ATP) is the classic agonist for the P2X (1) receptor, where it causes rapid desensitization, the agonist BzATP is among the most potent in activating this subtype. The aromatic sulfonates NF279 and NF449 are potent antagonists of the P2X (1) receptor. The structures of the two platelet P2Y receptors have been modeled, based on a rhodopsin template, to explain the basis for nucleotide recognition within the putative transmembrane binding sites. The P2Y (1) receptor model, especially, has been exploited in the design and optimization of antagonists targeted to interact selectively with that subtype.

Do receptors get pregnant too? Adrenergic receptor alterations in human pregnancy.

PubMed

Smiley, R M; Finster, M

1996-01-01

In this review we discuss adrenergic receptor number and function during pregnancy, with emphasis on evidence that pregnancy results in specific receptor alterations from the nonpregnant state. Changes in adrenergic receptor function or distribution in vascular smooth muscle may be in part responsible for the decreased vascular responsiveness seen in human pregnancy, and the lack of the normal alterations may be a part of the syndromes of gestational hypertension, including preeclampsia-eclampsia. The onset of labor may be influenced by adrenergic modulation, and receptor or postreceptor level molecular alterations may trigger or facilitate normal or preterm labor. Human studies are emphasized when possible to assess the role of adrenergic signal transduction regulation in the physiology and pathophysiology of normal and complicated human pregnancy.

Presynaptic inhibition of transmitter release from rat sympathetic neurons by bradykinin.

PubMed

Edelbauer, Hannah; Lechner, Stefan G; Mayer, Martina; Scholze, Thomas; Boehm, Stefan

2005-06-01

Bradykinin is known to stimulate neurons in rat sympathetic ganglia and to enhance transmitter release from their axons by interfering with the autoinhibitory feedback, actions that involve protein kinase C. Here, bradykinin caused a transient increase in the release of previously incorporated [3H] noradrenaline from primary cultures of dissociated rat sympathetic neurons. When this effect was abolished by tetrodotoxin, bradykinin caused an inhibition of tritium overflow triggered by depolarizing K+ concentrations. This inhibition was additive to that caused by the alpha2-adrenergic agonist UK 14304, desensitized within 12 min, was insensitive to pertussis toxin, and was enhanced when protein kinase C was inactivated. The effect was half maximal at 4 nm and antagonized competitively by the B2 receptor antagonist Hoe 140. The cyclooxygenase inhibitor indomethacin and the angiotensin converting enzyme inhibitor captopril did not alter the inhibition by bradykinin. The M-type K+ channel opener retigabine attenuated the secretagogue action of bradykinin, but left its inhibitory action unaltered. In whole-cell patch-clamp recordings, bradykinin reduced voltage-activated Ca2+ currents in a pertussis toxin-insensitive manner, and this action was additive to the inhibition by UK 14304. These results demonstrate that bradykinin inhibits noradrenaline release from rat sympathetic neurons via presynaptic B2 receptors. This effect does not involve cyclooxygenase products, M-type K+ channels, or protein kinase C, but rather an inhibition of voltage-gated Ca2+ channels.

Preventive mechanisms of agmatine against ischemic acute kidney injury in rats.

PubMed

Sugiura, Takahiro; Kobuchi, Shuhei; Tsutsui, Hidenobu; Takaoka, Masanori; Fujii, Toshihide; Hayashi, Kentaro; Matsumura, Yasuo

2009-01-28

The excitation of renal sympathetic nervous system plays an important role in the development of ischemic acute kidney injury in rats. Recently, we found that agmatine, an adrenaline alpha(2)/imidazoline I(1)-receptor agonist, has preventive effects on ischemic acute kidney injury by suppressing the enhanced renal sympathetic nerve activity during renal ischemia and by decreasing the renal venous norepinephrine overflow after reperfusion. In the present study, we investigated preventive mechanisms of agmatine against ischemic acute kidney injury in rats. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after the contralateral nephrectomy. Pretreatment with efaroxan (30 mumol/kg, i.v.), an alpha(2)/I(1)-receptor antagonist, abolished the suppressive effects of agmatine on the enhanced renal sympathetic nerve activity during renal ischemia and on the elevated norepinephrine overflow after reperfusion, and eliminated the preventing effects of agmatine on the ischemia/reperfusion-induced renal dysfunction and histological damage. On the other hand, pretreatment with yohimbine (6 mumol/kg, i.v.), an alpha(2)-receptor antagonist, eliminated the preventing effects of agmatine on the ischemia/reperfusion-induced renal injury and norepinephrine overflow, without affecting the lowering effect of agmatine on renal sympathetic nerve activity. These results indicate that agmatine prevents the ischemic renal injury by sympathoinhibitory effect probably via I(1) receptors in central nervous system and by suppressing the norepinephrine overflow through alpha(2) or I(1) receptors on sympathetic nerve endings.

Function of brain α2B-adrenergic receptor characterized with subtype-selective α2B antagonist and KO mice.

PubMed

Luhrs, Lauren; Manlapaz, Cynthia; Kedzie, Karen; Rao, Sandhya; Cabrera-Ghayouri, Sara; Donello, John; Gil, Daniel

2016-12-17

Noradrenergic signaling, through the α 2A and α 2C adrenergic receptors modulates the cognitive and behavioral symptoms of disorders such as schizophrenia, attention deficit hyperactivity disorder (ADHD), and addiction. However, it is unknown whether the α 2B receptor has any significant role in CNS function. The present study elucidates the potential role of the α 2B receptor in CNS function via the discovery and use of the first subtype-selective α 2B antagonist (AGN-209419), and behavioral analyses of α-receptor knockout (KO) mice. Using AGN-209419 as radioligand, α 2B receptor binding sites were identified within the olfactory bulb, cortex, thalamus, cerebellum, and striatum. Based on the observed expression patterns of α 2 subtypes in the brain, we compared α 2B KO, α 2A KO and α 2C KO mice behavioral phenotypes with their respective wild-type lines in anxiety (plus maze), compulsive (marble burying), and sensorimotor (prepulse inhibition) tasks. α 2B KO mice exhibited increased marble burying and α 2C KO mice exhibited an increased startle response to a pulse stimulus, but otherwise intact prepulse inhibition. To further explore compulsive behavior, we evaluated novelty-induced locomotor hyperactivity and found that α 2B KO and α 2C KO mice exhibited increased locomotion in the open field. Interestingly, when challenged with amphetamine, α 2C KO mice increased activity at lower doses relative to either α 2A KO or WT mice. However, α 2B KO mice exhibited stereotypy at doses of amphetamine that were only locomotor stimulatory to all other genotypes. Following co-administration of AGN-209419 with low-dose amphetamine in WT mice, stereotypy was observed, mimicking the α 2B KO phenotype. These findings suggest that the α 2B receptor is involved in CNS behaviors associated with sensorimotor gating and compulsivity, and may be therapeutically relevant for disorders such as schizophrenia, ADHD, post-traumatic stress disorder, addiction, and obsessive compulsive disorder. Copyright © 2016. Published by Elsevier Ltd.

Lysergic acid diethylamide (LSD) administration selectively downregulates serotonin2 receptors in rat brain.

PubMed

Buckholtz, N S; Zhou, D F; Freedman, D X; Potter, W Z

1990-04-01

A dosage regimen of lysergic acid diethylamide (LSD) that reliably produces behavioral tolerance in rats was evaluated for effects on neurotransmitter receptor binding in rat brain using a variety of radioligands selective for amine receptor subtypes. Daily administration of LSD [130 micrograms/kg (0.27 mumol/kg) intraperitoneally (IP)] for 5 days produced a decrease in serotonin2 (5-hydroxytryptamine2, 5-HT2) binding in cortex (measured 24 hours after the last drug administration) but did not affect binding to other receptor systems (5-HT1A, 5-HT1B, beta-adrenergic, alpha 1- or alpha 2-adrenergic, D2-dopaminergic) or to a recognition site for 5-HT uptake. The decrease was evident within 3 days of LSD administration but was not demonstrable after the first LSD dose. Following 5 days of LSD administration the decrease was still present 48 hours, but not 96 hours, after the last administration. The indole hallucinogen psilocybin [1.0 mg/kg (3.5 mumol/kg) for 8 days] also produced a significant decrease in 5HT2 binding, but neither the nonhallucinogenic analog bromo-LSD [1.3 mg/kg (2.4 mumol/kg) for 5 days] nor mescaline [10 mg/kg (40.3 mumol/kg) for 5 or 10 days] affected 5-HT2 binding. These observations suggest that LSD and other indole hallucinogens may act as 5-HT2 agonists at postsynaptic 5-HT2 receptors. Decreased 5-HT2 binding strikingly parallels the development and loss of behavioral tolerance seen with repeated LSD administration, but the decreased binding per se cannot explain the gamut of behavioral tolerance and cross-tolerance phenomena among the indole and phenylethylamine hallucinogens.

CLONING, EXPRESSION AND CHARACTERIZATION OF THE ANDROGEN RECEPTOR AND ISOLATION OF ESTROGEN RECEPTOR ALPHA FROM THE FATHEAD MINNOW (PIMEPHALES PROMELAS)

EPA Science Inventory

In vitro screening assays designed to identify hormone mimics or antagonists, including those recommended for use in the EPA's Tier 1 screening battery, typically use mammalian estrogen (ER) and androgen receptors (AR) such as rat or human. Although we know that the amino acid s...

Cloning, cell-type specificity, and regulatory function of the mouse alpha(1B)-adrenergic receptor promoter.

PubMed

Zuscik, M J; Piascik, M T; Perez, D M

1999-12-01

The functionality of a 3422-base pair promoter fragment from the mouse alpha(1B)-adrenergic receptor (alpha(1B)AR) gene was examined. This fragment, cloned from a mouse genomic library, was found to have significant sequence homology to the known human and rat alpha(1B)AR promoters. However, the consensus motif of several key cis-acting elements is not conserved among the rat, human, and mouse genes, suggesting species specificity. Confirming fidelity of the murine promoter, robust in vitro expression of a chloramphenicol acetyltransferase (CAT) reporter was detected in known alpha(1B)AR-expressing BC(3)H1, NB41A3, and DDT(1)MF-2 cells transiently transfected with a promoter-CAT construct. Conversely, minimal CAT expression was detected in known alpha(1B)AR-negative RAT-1 and R3T3 cells. These findings were extended by transfecting the same promoter-CAT construct into various primary cell types. In support of the hypothesis that alpha(1)ARs are differentially expressed in the smooth muscle of the vasculature, primary cultures of superior mesenteric and renal artery vascular smooth muscle cells showed significantly stronger CAT expression than did vascular smooth muscle cells derived from pulmonary, femoral, and iliac arteries. Primary osteoblastic bone-forming cells, which are known to be alpha(1B)AR negative, showed minimal CAT expression. Indicating regulatory function through cis-acting elements, RAT-1, R3T3, NB41A3, BC(3)H1, and DDT(1)MF2 cells transfected with the promoter-CAT construct all showed increased CAT production when challenged with forskolin or hypoxic conditions. Additionally, tissue-specific regulation of the promoter was observed when cells were simultaneously challenged with both forskolin and hypoxia. These results collectively demonstrate that a 3.4-kb PvuII fragment of the murine alpha(1B)AR gene promoter can: 1) drive tissue-specific production of a CAT reporter in both clonal and primary cell lines; and 2) confer tissue-specific regulation of that CAT reporter when induced by challenge with forskolin and/or hypoxic conditions.

Physiological regulation of MMPs and tPA/PAI in the arterial wall of rats by noradrenergic tone and angiotensin II.

PubMed

Dab, Houcine; Hachani, Rafik; Dhaouadi, Nedra; Hodroj, Wassim; Sakly, Mohsen; Randon, Jacques; Bricca, Giampiero; Kacem, Kamel

2012-03-01

The interactions between the sympathetic nervous system (SNS) and angiotensin II (ANG II), and their direct effects in vitro on the enzymes involved in vascular extracellular matrix (ECM) degradation, were examined. Rats were treated with guanethidine, losartan or the combined treatments. mRNA, protein and activity of matrix metalloproteinase (MMP)-2 and MMP-9 and mRNA of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) were quantified in abdominal aorta (AA) and femoral artery (FA). Norepinephrine (NE) or ANG II with adrenergic (β, α1 and α2) or losartan antagonists was tested for MMP mRNA response in cultured vascular smooth muscle cells (VSMCs). Combined treatment enhances the inhibition of MMP-2 mRNA and protein level induced by simple treatment in AA. However MMP-9 in AA and MMP mRNA in FA were reduced in the same order by treatments. MMP activities were not affected by treatments. The t-PA/PAI-1 ratio, which reflects the fibrinolytic balance, remained higher after treatments. In cultured VSMCs, NE induced stimulation of MMP mRNA via α2 and β adrenergic receptors and MMP-2 activity via β adrenergic receptors, while ANG II-induced stimulation was abrogated by losartan. Overall, there is a synergic inhibition of both systems on the level of MMP-2 in AA.

Mapping of the acetylcholine binding site of the nicotinic acetylcholine receptor: ( sup 3 H)nicotine as an agonist photoaffinity label

DOE Office of Scientific and Technical Information (OSTI.GOV)

Middleton, R.E.; Cohen, J.B.

1991-07-16

The agonist ({sup 3}H)nicotine was used as a photoaffinity label for the acetylcholine binding sties on the Torpedo nicotinic acetylcholine receptor (AChR). ({sup 3}H)Nicotine binds at equilibrium with K{sub eq} = 0.6 {mu}M to the agonist binding sites. Irradiation with 254-nm light of AChR-rich membranes equilibrated with ({sup 3}H)nicotine resulted in covalent incorporation into the {alpha}- and {gamma}-subunits, which was inhibited by agonists and competitive antagonists but not by noncompetitive antagonists. Inhibition of labeling by d-tubocurarine demonstrated that the {alpha}-subunit was labeled via both agonist sites but the {gamma}-subunit was labeled only via the site that binds d-tubocurarine with highmore » affinity. Chymotryptic digestion of the {alpha}-subunit confirmed that Try-198 was the principal amino acid labeled by ({sup 3}H)nicotine. This confirmation required a novel radiosequencing strategy employing o-phthalaldehyde ({sup 3}H)Nicotine, which is the first photoaffinity agonist used, labels primarily Tyr-198 in contrast to competitive antagonist affinity labels, which label primarily Tyr-190 and Cys-192/Cys-193.« less

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

Fu, Qin; Hu, Yuting; Wang, Qingtong; Liu, Yongming; Li, Ning; Xu, Bing; Kim, Sungjin; Chiamvimonvat, Nipavan; Xiang, Yang K

2017-03-15

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 β 2 -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 β 2 -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. 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 β 2 -adrenergic receptor (β 2 AR) 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 reduced contractile response to adrenergic stimulation when compared with those of control mice fed normal chow. Genetic deletion of the β 2 AR led to a normalized adrenergic response and preserved cardiac contractile reserve in HFD-fed mice. Together, these data indicate that HFD promotes phosphorylation of the β 2 AR, contributing to impairment of cardiac contractile reserve before cardiac structural and functional remodelling, suggesting that early intervention in the insulin-adrenergic signalling network might be effective in prevention of cardiac complications in diabetes. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

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 reduced contractile response to adrenergic stimulation when compared with those of control mice fed normal chow. Genetic deletion of the β2AR led to a normalized adrenergic response and preserved cardiac contractile reserve in HFD‐fed mice. Together, these data indicate that HFD promotes phosphorylation of the β2AR, contributing to impairment of cardiac contractile reserve before cardiac structural and functional remodelling, suggesting that early intervention in the insulin–adrenergic signalling network might be effective in prevention of cardiac complications in diabetes. PMID:27983752

Identification of putative agouti-related protein(87-132)-melanocortin-4 receptor interactions by homology molecular modeling and validation using chimeric peptide ligands.

PubMed

Wilczynski, Andrzej; Wang, Xiang S; Joseph, Christine G; Xiang, Zhimin; Bauzo, Rayna M; Scott, Joseph W; Sorensen, Nicholas B; Shaw, Amanda M; Millard, William J; Richards, Nigel G; Haskell-Luevano, Carrie

2004-04-22

Agouti-related protein (AGRP) is one of only two naturally known antagonists of G-protein-coupled receptors (GPCRs) identified to date. Specifically, AGRP antagonizes the brain melanocortin-3 and -4 receptors involved in energy homeostasis. Alpha-melanocyte stimulating hormone (alpha-MSH) is one of the known endogenous agonists for these melanocortin receptors. Insight into putative interactions between the antagonist AGRP amino acids with the melanocortin-4 receptor (MC4R) may be important for the design of unique ligands for the treatment of obesity related diseases and is currently lacking in the literature. A three-dimensional homology molecular model of the mouse MC4 receptor complex with the hAGRP(87-132) ligand docked into the receptor has been developed to identify putative antagonist ligand-receptor interactions. Key putative AGRP-MC4R interactions include the Arg111 of hAGRP(87-132) interacting in a negatively charged pocket located in a cavity formed by transmembrane spanning (TM) helices 1, 2, 3, and 7, capped by the acidic first extracellular loop (EL1) and specifically with the conserved melanocortin receptor residues mMC4R Glu92 (TM2), mMC4R Asp114 (TM3), and mMC4R Asp118 (TM3). Additionally, Phe112 and Phe113 of hAGRP(87-132) putatively interact with an aromatic hydrophobic pocket formed by the mMC4 receptor residues Phe176 (TM4), Phe193 (TM5), Phe253 (TM6), and Phe254 (TM6). To validate the AGRP-mMC4R model complex presented herein from a ligand perspective, we generated nine chimeric peptide ligands based on a modified antagonist template of the hAGRP(109-118) (Tyr-c[Asp-Arg-Phe-Phe-Asn-Ala-Phe-Dpr]-Tyr-NH(2)). In these chimeric ligands, the antagonist AGRP Arg-Phe-Phe residues were replaced by the melanocortin agonist His/D-Phe-Arg-Trp amino acids. These peptides resulted in agonist activity at the mouse melanocortin receptors (mMC1R and mMC3-5Rs). The most notable results include the identification of a novel subnanomolar melanocortin peptide template Tyr-c[Asp-His-DPhe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) that is equipotent to alpha-MSH at the mMC1, mMC3, and mMC5 receptors but is 30-fold more potent than alpha-MSH at the mMC4R. Additionally, these studies identified a new and novel >200-fold MC4R versus MC3R selective peptide Tyr-c[Asp-D-Phe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) template. Furthermore, when the His-DPhe-Arg-Trp sequence is used to replace the hAGRP Arg-Phe-Phe residues in the "mini"-AGRP (hAGRP87-120, C105A) template, a potent nanomolar agonist resulted at the mMC1R and MC3-5Rs.

Evaluation of GABAergic neuroactive steroid 3alpha-hydroxy-5alpha-pregnane-20-one as a neurobiological substrate for the anti-anxiety effect of ethanol in rats.

PubMed

Hirani, Khemraj; Sharma, Ajay N; Jain, Nishant S; Ugale, Rajesh R; Chopde, Chandrabhan T

2005-07-01

Acute systemic ethanol administration is known to elevate plasma and cerebral levels of neuroactive steroid 3alpha-hydroxy-5alpha-pregnane-20-one (3alpha, 5alpha-THP; allopregnanolone) to a concentration sufficient to potentiate GABA(A) receptors. We have earlier demonstrated that 3alpha, 5alpha-THP mediates the antidepressant-like effect of ethanol in Porsolt forced swim test. The aim of the present study is to explain the relationship between endogenous GABAergic neurosteroids and anxiolytic effect of ethanol in Sprague-Dawley rats. The mediation of 3alpha, 5alpha-THP in the anti-anxiety effect of ethanol was assessed by pharmacological interactions of ethanol with various endogenous neurosteroidal modulators and using simulated physiological conditions of altered neurosteroid content in elevated plus maze (EPM) test. Pretreatment of 3alpha, 5alpha-THP (0.5-2.5 mug/rat, i.c.v.) or neurosteroidogenic agents such as 3alpha, 5alpha-THP precursor progesterone (5 or 10 mg/kg, i.p.), 11-beta hydroxylase inhibitor metyrapone (50 or 100 mg/kg, i.p.) or the GABA(A) receptor agonist muscimol (25 ng/rat, i.c.v.) significantly potentiated the anti-anxiety effect of ethanol (1 g/kg, i.p.). On the other hand, the GABAergic antagonistic neurosteroid dehydroepiandrosterone sulphate (DHEAS) (1 mg/kg, i.p.), the GABA(A) receptor blocker bicuculline (1 mg/kg, i.p.), the 5alpha-reductase inhibitor finasteride (50 x 2 mg/kg, s.c.) or the mitochondrial diazepam binding inhibitory receptor antagonist PK11195 (1 mg/kg, i.p.) reduced ethanol-induced preference of time spent and number of entries into open arms. Anti-anxiety effect of ethanol was abolished in adrenalectomized (ADX) rats as compared to sham-operated control. This ADX-induced blockade was restored by prior systemic injection of progesterone, signifying the contribution of peripheral steroidogenesis in ethanol anxiolysis. Socially isolated animals known to exhibit decreased brain 3alpha, 5alpha-THP and GABA(A) receptor functions displayed reduced sensitivity to the effects of ethanol and 3alpha, 5alpha-THP in EPM test. Our results demonstrated the contributory role of neuroactive steroid 3alpha, 5alpha-THP in the anti-anxiety effect of ethanol. It is speculated that ethanol-induced modulation of endogenous GABAergic neurosteroids, especially 3alpha, 5alpha-THP, might be crucial pertinent to the etiology of 'trait' anxiety (tension reduction) and ethanol abuse.

Functional subcellular distribution of β1- and β2-adrenergic receptors in rat ventricular cardiac myocytes

PubMed Central

Cros, Caroline; Brette, Fabien

2013-01-01

β-adrenergic stimulation is a key regulator of cardiac function. The localization of major cardiac adrenergic receptors (β1 and β2) has been investigated using biochemical and biophysical approaches and has led to contradictory results. This study investigates the functional subcellular localization of β1- and β2-adrenergic receptors in rat ventricular myocytes using a physiological approach. Ventricular myocytes were isolated from the hearts of rat and detubulated using formamide. Physiological cardiac function was measured as Ca2+ transient using Fura-2-AM and cell shortening. Selective activation of β1- and β2-adrenergic receptors was induced with isoproterenol (0.1 μmol/L) and ICI-118,551 (0.1 μmol/L); and with salbutamol (10 μmol/L) and atenolol (1 μmol/L), respectively. β1- and β2-adrenergic stimulations induced a significant increase in Ca2+ transient amplitude and cell shortening in intact rat ventricular myocytes (i.e., surface sarcolemma and t-tubules) and in detubulated cells (depleted from t-tubules, surface sarcolemma only). Both β1- and β2-adrenergic receptors stimulation caused a greater effect on Ca2+ transient and cell shortening in detubulated myocytes than in control myocytes. Quantitative analysis indicates that β1-adrenergic stimulation is ∼3 times more effective at surface sarcolemma compared to t-tubules, whereas β2- adrenergic stimulation occurs almost exclusively at surface sarcolemma (∼100 times more effective). These physiological data demonstrate that in rat ventricular myocytes, β1-adrenergic receptors are functionally present at surface sarcolemma and t-tubules, while β2-adrenergic receptors stimulation occurs only at surface sarcolemma of cardiac cells. PMID:24303124

Discovery of potent peptide-mimetic antagonists for the human thrombin receptor, protease-activated receptor-1 (PAR-1).

PubMed

Maryanoff, Bruce E; Zhang, Han-Cheng; Andrade-Gordon, Patricia; Derian, Claudia K

2003-03-01

Protease-activated receptors (PARs) represent a unique family of seven-transmembrane G-protein-coupled receptors, which are enzymatically cleaved to expose a new extracellular N-terminus that acts as a tethered activating ligand. PAR-1 is cleaved and activated by the serine protease alpha-thrombin, is expressed in various tissues (e.g. platelets and vascular cells), and is involved in cellular responses associated with hemostasis, proliferation, and tissue injury. By using a de novo design approach, we have discovered a series of potent heterocycle-based peptide-miimetic antagonists of PAR-1, exemplified by advanced leads RWJ-56110 (22) and RWJ-58259 (32). These compounds are potent, selective PAR-1 antagonists, devoid of PAR-1 agonist and thrombin inhibitory activity: they bind to PAR-1, interfere with calcium mobilization and cellular functions associated with PAR-1, and do not affect PAR-2, PAR-3, or PAR-4. RWJ-56110 was determined to be a direct inhibitor of PAR-1 activation and internalization, without affecting PAR-1 N-terminal cleavage. At high concentrations of alpha-thrombin, RWJ-56110 fully blocked activation responses in human vascular cells, but not in human platelets; whereas, at high concentrations of TRAP-6, RWJ-56110 blocked activation responses in both cell types. This result is consistent with the presence of another thrombin receptor on human platelets, namely PAR-4. RWJ-56110 and RWJ-58259 clearly interrupt the binding of a tethered ligand to its receptor. RWJ-58259 demonstrated antirestenotic activity in a rat balloon angioplasty model and antithrombotic activity in a cynomolgus monkey arterial injury model. Such PAR-1 antagonists should not only serve as useful tools to delineate the physiological and pathophysiological roles of PAR-1, but also may have therapeutic potential for treating thrombosis and restenosis in humans.

Co-regulation of the atrial natriuretic factor and cardiac myosin light chain-2 genes during alpha-adrenergic stimulation of neonatal rat ventricular cells. Identification of cis sequences within an embryonic and a constitutive contractile protein gene which mediate inducible expression.

PubMed

Knowlton, K U; Baracchini, E; Ross, R S; Harris, A N; Henderson, S A; Evans, S M; Glembotski, C C; Chien, K R

1991-04-25

To study the mechanisms which mediate the transcriptional activation of cardiac genes during alpha adrenergic stimulation, the present study examined the regulated expression of three cardiac genes, a ventricular embryonic gene (atrial natriuretic factor, ANF), a constitutively expressed contractile protein gene (cardiac MLC-2), and a cardiac sodium channel gene. alpha 1-Adrenergic stimulation activates the expression and release of ANF from neonatal ventricular cells. As assessed by RNase protection analyses, treatment with alpha-adrenergic agonists increases the steady-state levels of ANF mRNA by greater than 15-fold. However, a rat cardiac sodium channel gene mRNA is not induced, indicating that alpha-adrenergic stimulation does not lead to an increase in the expression of all cardiac genes. Studies employing a series of rat ANF luciferase and rat MLC-2 luciferase fusion genes identify 315- and 92-base pair cis regulatory sequences within an embryonic gene (ANF) and a constitutively expressed contractile protein gene (MLC-2), respectively, which mediate alpha-adrenergic-inducible gene expression. Transfection of various ANF luciferase reporters into neonatal rat ventricular cells demonstrated that upstream sequences which mediate tissue-specific expression (-3003 to -638) can be segregated from those responsible for inducibility. The lack of inducibility of a cardiac Na+ channel gene, and the segregation of ANF gene sequences which mediate cardiac specific from those which mediate inducible expression, provides further insight into the relationship between muscle-specific and inducible expression during cardiac myocyte hypertrophy. Based on these results, a testable model is proposed for the induction of embryonic cardiac genes and constitutively expressed contractile protein genes and the noninducibility of a subset of cardiac genes during alpha-adrenergic stimulation of neonatal rat ventricular cells.

Adrenergic Receptors in Individual Ventricular Myocytes: The Beta-1 and Alpha-1B Are in All Cells, the Alpha-1A Is in a Subpopulation, and the Beta-2 and Beta-3 Are Mostly Absent.

PubMed

Myagmar, Bat-Erdene; Flynn, James M; Cowley, Patrick M; Swigart, Philip M; Montgomery, Megan D; Thai, Kevin; Nair, Divya; Gupta, Rumita; Deng, David X; Hosoda, Chihiro; Melov, Simon; Baker, Anthony J; Simpson, Paul C

2017-03-31

It is unknown whether every ventricular myocyte expresses all 5 of the cardiac adrenergic receptors (ARs), β1, β2, β3, α1A, and α1B. The β1 and β2 are thought to be the dominant myocyte ARs. Quantify the 5 cardiac ARs in individual ventricular myocytes. We studied ventricular myocytes from wild-type mice, mice with α1A and α1B knockin reporters, and β1 and β2 knockout mice. Using individual isolated cells, we measured knockin reporters, mRNAs, signaling (phosphorylation of extracellular signal-regulated kinase and phospholamban), and contraction. We found that the β1 and α1B were present in all myocytes. The α1A was present in 60%, with high levels in 20%. The β2 and β3 were detected in only ≈5% of myocytes, mostly in different cells. In intact heart, 30% of total β-ARs were β2 and 20% were β3, both mainly in nonmyocytes. The dominant ventricular myocyte ARs present in all cells are the β1 and α1B. The β2 and β3 are mostly absent in myocytes but are abundant in nonmyocytes. The α1A is in just over half of cells, but only 20% have high levels. Four distinct myocyte AR phenotypes are defined: 30% of cells with β1 and α1B only; 60% that also have the α1A; and 5% each that also have the β2 or β3. The results raise cautions in experimental design, such as receptor overexpression in myocytes that do not express the AR normally. The data suggest new paradigms in cardiac adrenergic signaling mechanisms. © 2017 American Heart Association, Inc.

Development of an image analysis screen for estrogen receptor alpha (ERα) ligands through measurement of nuclear translocation dynamics.

PubMed

Dull, Angie; Goncharova, Ekaterina; Hager, Gordon; McMahon, James B

2010-11-01

We have developed a robust high-content assay to screen for novel estrogen receptor alpha (ERα) agonists and antagonists by quantitation of cytoplasmic to nuclear translocation of an estrogen receptor chimera in 384-well plates. The screen utilizes a green fluorescent protein tagged-glucocorticoid/estrogen receptor (GFP-GRER) chimera which consisted of the N-terminus of the glucocorticoid receptor fused to the human ER ligand binding domain. The GFP-GRER exhibited cytoplasmic localization in the absence of ERα ligands, and translocated to the nucleus in response to stimulation with ERα agonists or antagonists. The BD Pathway 435 imaging system was used for image acquisition, analysis of translocation dynamics, and cytotoxicity measurements. The assay was validated with known ERα agonists and antagonists, and the Library of Pharmacologically Active Compounds (LOPAC 1280). Additionally, screening of crude natural product extracts demonstrated the robustness of the assay, and the ability to quantitate the effects of toxicity on nuclear translocation dynamics. The GFP-GRER nuclear translocation assay was very robust, with z' values >0.7, CVs <5%, and has been validated with known ER ligands, and inclusion of cytotoxicity filters will facilitate screening of natural product extracts. This assay has been developed for future primary screening of synthetic, pure natural products, and natural product extracts libraries available at the National Cancer Institute at Frederick. Copyright © 2010 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Selective androgen receptor modulators: in pursuit of tissue-selective androgens.

PubMed

Omwancha, Josephat; Brown, Terry R

2006-10-01

The androgen receptor mediates the androgenic and anabolic activity of the endogenous steroids testosterone and 5alpha-dihydrotestosterone. Current knowledge of the androgen receptor protein structure, and the molecular mechanisms surrounding the binding properties and activities of agonists and antagonists has led to the design and development of novel nonsteroidal ligands with selected tissue-specific androgen receptor agonist and antagonist activities. The activity of these compounds, termed selective androgen receptor modulators (SARMs), is directed toward the maintenance or enhancement of anabolic effects on bone and muscle with minimal androgenic effects on prostate growth. SARMs are of potential therapeutic value in the treatment of male hypogonadism, osteoporosis, frailty and muscle wasting, burn injury and would healing, anemia, mood and depression, benign prostatic hyperplasia and prostate cancer.

Photochemically enhanced binding of small molecules to the tumor necrosis factor receptor-1 inhibits the binding of TNF-[alpha

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, Percy H.; Scherle, Peggy A.; Muckelbauer, Jodi K.

2010-03-05

The binding of tumor necrosis factor alpha (TNF-{alpha}) to the type-1 TNF receptor (TNFRc1) plays an important role in inflammation. Despite the clinical success of biologics (antibodies, soluble receptors) for treating TNF-based autoimmune conditions, no potent small molecule antagonists have been developed. Our screening of chemical libraries revealed that N-alkyl 5-arylidene-2-thioxo-1,3-thiazolidin-4-ones were antagonists of this protein-protein interaction. After chemical optimization, we discovered IW927, which potently disrupted the binding of TNF-{alpha} to TNFRc1 (IC{sub 50} = 50 nM) and also blocked TNF-stimulated phosphorylation of I{kappa}-B in Ramos cells (IC{sub 50} = 600 nM). This compound did not bind detectably to themore » related cytokine receptors TNFRc2 or CD40, and did not display any cytotoxicity at concentrations as high as 100 {micro}M. Detailed evaluation of this and related molecules revealed that compounds in this class are 'photochemically enhanced' inhibitors, in that they bind reversibly to the TNFRc1 with weak affinity (ca. 40-100 mM) and then covalently modify the receptor via a photochemical reaction. We obtained a crystal structure of IV703 (a close analog of IW927) bound to the TNFRc1. This structure clearly revealed that one of the aromatic rings of the inhibitor was covalently linked to the receptor through the main-chain nitrogen of Ala-62, a residue that has already been implicated in the binding of TNF-{alpha} to the TNFRc1. When combined with the fact that our inhibitors are reversible binders in light-excluded conditions, the results of the crystallography provide the basis for the rational design of nonphotoreactive inhibitors of the TNF-{alpha}-TNFRc1 interaction.« less

Interleukin 1 receptor antagonist is a member of the interleukin 1 gene family: evolution of a cytokine control mechanism.

PubMed Central

Eisenberg, S P; Brewer, M T; Verderber, E; Heimdal, P; Brandhuber, B J; Thompson, R C

1991-01-01

Interleukin 1 receptor antagonist (IL-1ra) is a protein that binds to the IL-1 receptor and blocks the binding of both IL-1 alpha and -beta without inducing a signal of its own. Human IL-1ra has some sequence identity to human IL-1 beta, but the evolutionary relationship between these proteins has been unclear. We show that the genes for human, mouse, and rat IL-1ra are similar to the genes for IL-1 alpha and IL-1 beta in intron-exon organization, indicating that gene duplication events were important in the creation of this gene family. Furthermore, an analysis of sequence comparisons and mutation rates for IL-1 alpha, IL-1 beta, and IL-1ra suggests that the duplication giving rise to the IL-1ra gene was an early event in the evolution of the gene family. Comparisons between the mature sequences for IL-1ra, IL-1 alpha, and IL-1 beta suggest that IL-1ra has a beta-stranded structure like to IL-1 alpha and IL-1 beta, consistent with the three proteins being related. The N-terminal sequences of IL-1ra appear to be derived from a region of the genome different than those of IL-1 alpha and IL-1 beta, thus explaining their different modes of biosynthesis and suggesting an explanation for their different biological activities. Images PMID:1828896

Evaluation for the interaction between intrathecal melatonin and clonidine or neostigmine on formalin-induced nociception.

PubMed

Yoon, Myung Ha; Park, Heon Chang; Kim, Woong Mo; Lee, Hyung Gon; Kim, Yeo Ok; Huang, Lan Ji

2008-12-19

We examined the nature of pharmacological interaction after coadministration of melatonin with clonidine or neostigmine on formalin-induced nociception at the spinal level. Further, the role of melatonin receptor subtypes in melatonin-induced antinociception was clarified. Catheters were inserted into the intrathecal space of male Sprague-Dawley rats. Pain was assessed using the formalin test (induced by a subcutaneous injection of 50 microl of a 5% formalin solution to the hindpaw). Isobolographic analysis was used for the evaluation of drug interaction between melatonin and clonidine or neostigmine. Non-selective MT1/MT2 receptors antagonist (luzindole), MT2 receptor antagonist (4-P-PDOT), and MT3 receptor/alpha-1 adrenoceptor antagonist (prazosin) were intrathecally given to verify the involvement of the melatonin receptor subtypes in the antinociception of melatonin. Furthermore, the effect of intrathecal MT3 receptor ligand (GR 135531) was observed. Intrathecal melatonin, clonidine, and neostigmine dose-dependently suppressed the flinching response during phase 1 and phase 2 in the formalin test. Isobolographic analysis showed additivity between melatonin and clonidine or neostigmine in both phases. The antinociceptive effect of melatonin was antagonized by luzindole, 4-P-PDOT, and prazosin in the spinal cord. Intrathecal GR 135531 was ineffective against the formalin-induced flinching response. These results suggest that melatonin interacts additively with clonidine and neostigmine in the formalin-induced nociception at the spinal level. Furthermore, the antinociception of melatonin is mediated through the MT2 receptor, but not the MT3 receptor. However, it seems that alpha-1 adrenoceptor plays in the effect of melatonin.

Blockade of rat alpha3beta4 nicotinic receptor function by methadone, its metabolites, and structural analogs.

PubMed

Xiao, Y; Smith, R D; Caruso, F S; Kellar, K J

2001-10-01

The opioid agonist properties of (+/-)-methadone are ascribed almost entirely to the (-)-methadone enantiomer. To extend our knowledge of the pharmacological actions of methadone at ligand-gated ion channels, we investigated the effects of the two enantiomers of methadone and its metabolites R-(+)-2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium perchlorate (EDDP) and R-(+)-2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline hydrochloride (EMDP), as well as structural analogs of methadone, including (-)-alpha-acetylmethadol hydrochloride (LAAM) and (+)-alpha-propoxyphene, on rat alpha3beta4 neuronal nicotinic acetylcholine receptors (nAChRs) stably expressed in a human embryonic kidney 293 cell line, designated KXalpha3beta4R2. (+/-)-methadone inhibited nicotine-stimulated 86Rb+ efflux from the cells in a concentration-dependent manner with an IC50 value of 1.9 +/- 0.2 microM, indicating that it is a potent nAChR antagonist. The (-)- and (+)-enantiomers of methadone have similar inhibitory potencies on nicotine-stimulated 86Rb+ efflux, with IC50 values of approximately 2 microM. EDDP, the major metabolite of methadone, is even more potent, with an IC50 value of approximately 0.5 microM, making it one of the most potent nicotinic receptor blockers reported. In the presence of (+/-)-methadone, EDDP, or LAAM, the maximum nicotine-stimulated 86Rb+ efflux was markedly decreased, but the EC50 value for nicotine stimulation was altered only slightly, if at all, indicating that these compounds block alpha3beta4 nicotinic receptor function by a noncompetitive mechanism. Consistent with a noncompetitive mechanism, (+/-)-methadone, its metabolites, and structural analogs have very low affinity for nicotinic receptor agonist binding sites in membrane homogenates from KXalpha3beta4R2 cells. We conclude that both enantiomers of methadone and its metabolites as well as LAAM and (+)-alpha-propoxyphene are potent noncompetitive antagonists of alpha3beta4 nAChRs.

Contributions of Torpedo nicotinic acetylcholine receptor gamma Trp-55 and delta Trp-57 to agonist and competitive antagonist function.

PubMed

Xie, Y; Cohen, J B

2001-01-26

Results of affinity-labeling studies and mutational analyses provide evidence that the agonist binding sites of the nicotinic acetylcholine receptor (nAChR) are located at the alpha-gamma and alpha-delta subunit interfaces. For Torpedo nAChR, photoaffinity-labeling studies with the competitive antagonist d-[(3)H]tubocurarine (dTC) identified two tryptophans, gammaTrp-55 and deltaTrp-57, as the primary sites of photolabeling in the non-alpha subunits. To characterize the importance of gammaTrp-55 and deltaTrp-57 to the interactions of agonists and antagonists, Torpedo nAChRs were expressed in Xenopus oocytes, and equilibrium binding assays and electrophysiological recordings were used to examine the functional consequences when either or both tryptophans were mutated to leucine. Neither substitution altered the equilibrium binding of dTC. However, the deltaW57L and gammaW55L mutations decreased acetylcholine (ACh) binding affinity by 20- and 7,000-fold respectively. For the wild-type, gammaW55L, and deltaW57L nAChRs, the concentration dependence of channel activation was characterized by Hill coefficients of 1.8, 1.1, and 1.7. For the gammaW55L mutant, dTC binding at the alpha-gamma site acts not as a competitive antagonist but as a coactivator or partial agonist. These results establish that interactions with gamma Trp-55 of the Torpedo nAChR play a crucial role in agonist binding and in the agonist-induced conformational changes that lead to channel opening.

The pure estrogen receptor antagonist ICI 182,780 promotes a novel interaction of estrogen receptor-alpha with the 3',5'-cyclic adenosine monophosphate response element-binding protein-binding protein/p300 coactivators.

PubMed

Jaber, Basem M; Gao, Tong; Huang, Luping; Karmakar, Sudipan; Smith, Carolyn L

2006-11-01

Estrogen receptor-alpha (ERalpha) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. Abundant evidence demonstrates that ERalpha agonists promote, whereas antagonists inhibit, receptor binding to coactivators. In this report we demonstrate that binding of the ICI 182,780 (ICI) pure antiestrogen to ERalpha promotes its interaction with the cAMP response element-binding protein-binding protein (CBP)/p300 but not the p160 family of coactivators, demonstrating the specificity of this interaction. Amino acid mutations within the coactivator binding surface of the ERalpha ligand-binding domain revealed that CBP binds to this region of the ICI-liganded receptor. The carboxy-terminal cysteine-histidine rich domain 3 of CBP, rather than its amino-terminal nuclear interacting domain, shown previously to mediate agonist-dependent interactions of CBP with nuclear receptors, is required for binding to ICI-liganded ERalpha. Chromatin immunoprecipitation assays revealed that ICI but not the partial agonist/antagonist 4-hydroxytamoxifen is able to recruit CBP to the pS2 promoter, and this distinguishes ICI from this class of antiestrogens. Chromatin immunoprecipitation assays for pS2 and cytochrome P450 1B1 promoter regions revealed that ICI-dependent recruitment of CBP, but not receptor, to ERalpha targets is gene specific. ICI treatment did not recruit the steroid receptor coactivator 1 to the pS2 promoter, and it failed to induce the expression of this gene. Taken together, these data indicate that recruitment of the CBP coactivator/cointegrator without steroid receptor coactivator 1 to ERalpha is insufficient to promote transcription of ERalpha target genes.

Structure-Function of α1-Adrenergic Receptors

PubMed Central

Perez, Dianne M.

2007-01-01

Summary The Easson-Stedman hypothesis provided the rationale for the first studies of drug design for the α1-adrenergic receptor. Through chemical modifications of the catecholamine core structure, the need was established for a protonated amine, a β-hydroxyl on a chiral center, and an aromatic ring with substitutions capable of hydrogen bonding. After the receptors were cloned and three α1-adrenergic receptor subtypes were discovered, drug design became focused on the analysis of receptor structure and new interactions were uncovered. It became clear that α1 and β-adrenergic receptors did not share stringent homology in the ligand-binding pocket but this difference has allowed for more selective drug design. Novel discoveries on allosterism and agonist trafficking may be used in the future design of therapeutics with fewer side effects. This review will explore past and current knowledge of the structure-function of the α1-adrenergic receptor subtypes. PMID:17052695

Dwarfism and insulin resistance in male offspring caused by α1-adrenergic antagonism during pregnancy.

PubMed

Oelkrug, Rebecca; Herrmann, Beate; Geissler, Cathleen; Harder, Lisbeth; Koch, Christiane; Lehnert, Hendrik; Oster, Henrik; Kirchner, Henriette; Mittag, Jens

2017-10-01

Maternal and environmental factors control the epigenetic fetal programming of the embryo, thereby defining the susceptibility for metabolic or endocrine disorders in the offspring. Pharmacological interventions required as a consequence of gestational problems, e.g. hypertension, can potentially interfere with correct fetal programming. As epigenetic alterations are usually only revealed later in life and not detected in studies focusing on early perinatal outcomes, little is known about the long-term epigenetic effects of gestational drug treatments. We sought to test the consequences of maternal α1-adrenergic antagonism during pregnancy, which can occur e.g. during hypertension treatment, for the endocrine and metabolic phenotype of the offspring. We treated C57BL/6NCrl female mice with the α1-adrenergic antagonist prazosin during pregnancy and analyzed the male and female offspring for endocrine and metabolic abnormalities. Our data revealed that maternal α1-adrenergic blockade caused dwarfism, elevated body temperature, and insulin resistance in male offspring, accompanied by reduced IGF-1 serum concentrations as the result of reduced hepatic growth hormone receptor (Ghr) expression. We subsequently identified increased CpG DNA methylation at the transcriptional start site of the alternative Ghr promotor caused by the maternal treatment, which showed a strong inverse correlation to hepatic Ghr expression. Our results demonstrate that maternal α1-adrenergic blockade can constitute an epigenetic cause for dwarfism and insulin resistance. The findings are of immediate clinical relevance as combined α/β-adrenergic blockers are first-line treatment of maternal hypertension. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

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

PubMed Central

Amanfu, Robert K.

2014-01-01

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

Effects of glutamate and {alpha}2-noradrenergic receptor antagonists on the development of neurotoxicity produced by chronic rotenone in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Mesbah; Danysz, Wojciech; Schmidt, Werner Juergen

2009-10-15

Systemic inhibition of complex I by rotenone in rats represents a model of Parkinson's disease (PD). The aim of this study was to elucidate whether neramexane (NMDA, nicotinic {alpha}9/{alpha}10 and 5-HT{sub 3} receptor antagonist), idazoxan ({alpha}{sub 2}-adrenoceptor antagonist) or 2-methyl-6-(phenyl-ethyl)-pyrimidine (MPEP, metabotropic glutamate receptor 5 antagonist) prevents rotenone-induced parkinsonian-like behaviours and neurochemical changes in rats. Rotenone (2.5 mg/kg i.p. daily) was administered over 60 days together with saline, neramexane (5 mg/kg i.p., b.i.d.), idazoxan (2.5 mg/kg i.p., b.i.d.) or MPEP (2.5 mg/kg i.p., b.i.d.). The same doses of neramexane, idazoxan and MPEP were administered to rats treated with vehicle insteadmore » of rotenone. Treatment-related effects on parkinsonian-like behaviours, such as hypokinesia/rigidity and locomotor activity, were evaluated. Moreover, concentrations of dopamine, serotonin and their metabolites were measured in rats from each experimental group. Over the 60-day treatment period, the rotenone + saline treated animals developed hypokinesia, expressed as an increase in the bar and grid descent latencies in the catalepsy test, and a decrease in locomotor activity. Neramexane and idazoxan partially prevented the development of catalepsy in rotenone-treated rats. Co-administration of MPEP with rotenone resulted only in a decrease in descent latency in the grid test on day 60. Chronic rotenone treatment reduced concentrations of dopamine and serotonin in the anterior striatum, which was blocked by co-treatment with neramexane or idazoxan but not with MPEP. Only neramexane treatment blocked the rotenone-induced decrease in dopamine levels in the substantia nigra pars compacta. In conclusion, neramexane and idazoxan counteracted to some extent the development of parkinsonian symptoms and neurochemical alterations in the rotenone model of Parkinson's disease.« less

Agmatine enhances caloric intake and dietary carbohydrate preference in satiated rats.

PubMed

Prasad, A; Prasad, C

1996-10-01

Agmatine is a decarboxylated metabolite of arginine endogenous to the brain. In vitro, agmatine inhibits binding of clonidine to alpha 2-adrenergic and imidazoline receptors. We have shown that acute administration of agmatine increases caloric intake and dietary carbohydrate preference in satiated rats. In contrast, agmatine does not modulate caloric intake in hungry rats. Furthermore, repeated administration of high doses of agmatine does not decrease its ability to stimulate appetite.

Pharmacological characterisation of strychnine and brucine analogues at glycine and alpha7 nicotinic acetylcholine receptors.

PubMed

Jensen, Anders A; Gharagozloo, Parviz; Birdsall, Nigel J M; Zlotos, Darius P

2006-06-06

Strychnine and brucine from the plant Strychnos nux vomica have been shown to have interesting pharmacological effects on several neurotransmitter receptors, including some members of the superfamily of ligand-gated ion channels. In this study, we have characterised the pharmacological properties of tertiary and quaternary analogues as well as bisquaternary dimers of strychnine and brucine at human alpha1 and alpha1beta glycine receptors and at a chimera consisting of the amino-terminal domain of the alpha7 nicotinic receptor (containing the orthosteric ligand binding site) and the ion channel domain of the 5-HT3A serotonin receptor. Although the majority of the analogues displayed significantly increased Ki values at the glycine receptors compared to strychnine and brucine, a few retained the high antagonist potencies of the parent compounds. However, mirroring the pharmacological profiles of strychnine and brucine, none of the analogues displayed significant selectivity between the alpha1 and alpha1beta subtypes. The structure-activity relationships for the compounds at the alpha7/5-HT3 chimera were significantly different from those at the glycine receptors. Most strikingly, quaternization of strychnine and brucine with substituents possessing different steric and electronic properties completely eliminated the activity at the glycine receptors, whereas binding affinity to the alpha7/5-HT3 chimera was retained for the majority of the quaternary analogues. This study provides an insight into the structure-activity relationships for strychnine and brucine analogues at these ligand-gated ion channels.

Development of an enzyme-linked immunosorbent assay and a beta-1 adrenergic receptor-based assay for monitoring the drug atenolol.

PubMed

Sapir, A; Shalev, A Hariton; Skalka, N; Bronshtein, A; Altstein, M

2013-03-01

Two approaches for monitoring atenolol (ATL) were applied: an immunochemical assay and a competitive-binding assay, based on the interaction between ATL and its target receptor, β1 adrenergic receptor (β1AR). Polyclonal antibodies (Abs) for ATL were generated, and a highly specific microplate immunochemical assay, that is, an enzyme-linked immunosorbent assay (ELISA), for its detection was developed. The ATL ELISA exhibited I50 and limit of detection (I20) values of 0.15 ± 0.048 and 0.032 ± 0.016 ng/ml, respectively, and the Abs did not cross-react with any of the tested beta-blocker drugs. Furthermore, a human β1AR (h-β1AR) was stably expressed in Spodoptera frugiperda cells (Sf9). The receptor was employed to develop a competitive-binding assay that monitored binding of ATL in the presence of isoproteranol by quantification of secondary messenger, cyclic adenosine monophosphate (cAMP), levels in the transfected cells. The assay showed that the recombinant h-β1AR was functional, could bind the agonistic ligand isoproterenol as well as the antagonist ATL, as indicated by a dose-dependent elevation of cAMP in the presence of isoproteranol, and decrease after ATL addition. The highly efficient and sensitive ELISA and the receptor assay represent two methods suitable for efficient and cost-effective large-scale, high-throughput monitoring of ATL in environmental, agricultural, and biological samples. Copyright © 2012 SETAC.

[Quetiapine in substance use disorders, abuse and dependence possibility: a review].

PubMed

Erdoğan, Serap

2010-01-01

Quetiapine is an atypical antipsychotic approved by the FDA (Food and Drug Administration) for use in the treatment of schizophrenia, acute mania, and bipolar depression. Pharmacologically, it has antagonistic effects on serotonin 5-HT1A and 5-HT2A, dopamine D1 and D2, histamine H1, and adrenergic alpha1 and alpha2 receptors. In addition to reports of its use in schizophrenia and bipolar disorder, many studies have examined the use of quetiapine in the treatment of anxiety disorders and substance use disorders. In the treatment of patients with psychotic or bipolar disorder with a comorbid substance abuse disorder even though quetiapine was prescribed primarily for the treatment of the underlying psychotic symptoms, patients taking this medication reported a significant reduction in substance use. Yet, there are also case reports of quetiapine abuse and dependence; in particular among prisoners and patients diagnosed with substance abuse. Though quetiapine should be used peroral, it is also used intranasally and intravenously in these patient groups. Moreover, in some cases quetiapine is combined with other substances, such as cocaine or marijuana, to increase sedation. This abuse of quetiapine is thought to occur due to the anxiolytic and sedative effects of the drug. There are no controlled studies on quetiapine dependence in the literature and it remains unknown whether or not quetiapine causes dependence. This review aimed to present all published case reports on quetiapine abuse and to discuss the possible mechanisms that underlie its abuse and dependence.

Dopamine depresses excitatory synaptic transmission onto rat subicular neurons via presynaptic D1-like dopamine receptors.

PubMed

Behr, J; Gloveli, T; Schmitz, D; Heinemann, U

2000-07-01

Schizophrenia is considered to be associated with an abnormal functioning of the hippocampal output. The high clinical potency of antipsychotics that act as antagonists at dopamine (DA) receptors indicate a hyperfunction of the dopaminergic system. The subiculum obtains information from area CA1 and the entorhinal cortex and represents the major output region of the hippocampal complex. To clarify whether an enhanced dopaminergic activity alters the hippocampal output, the effect of DA on alveus- and perforant path-evoked excitatory postsynaptic currents (EPSCs) in subicular neurons was examined using conventional intracellular and whole cell voltage-clamp recordings. Dopamine (100 microM) depressed alveus-elicited (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated EPSCs to 56 +/- 8% of control while perforant path-evoked EPSCs were attenuated to only 76 +/- 7% of control. Dopamine had no effect on the EPSC kinetics. Dopamine reduced the frequency of spontaneous miniature EPSCs without affecting their amplitudes. The sensitivity of subicular neurons to the glutamate receptor agonist (S)-alpha-amino-3-hydoxy-5-methyl-4-isoxazolepropionic acid was unchanged by DA pretreatment, excluding a postsynaptic mechanism for the observed reduction of excitatory synaptic transmission. The effect of DA on evoked EPSCs was mimicked by the D1 receptor agonist SFK 38393 and partially antagonized by the D1 receptor antagonist SCH 23390. While the D2 receptor agonist quinelorane failed to reduce the EPSCs, the D2 receptor antagonist sulpiride did not block the action of DA. The results indicate that DA strongly depresses the hippocampal and the entorhinal excitatory input onto subicular neurons by decreasing the glutamate release following activation of presynaptic D1-like DA receptors.

Opposing Effects of α2- and β-Adrenergic Receptor Stimulation on Quiescent Neural Precursor Cell Activity and Adult Hippocampal Neurogenesis

PubMed Central

Prosper, Boris W.; Marathe, Swanand; Husain, Basma F. A.; Kernie, Steven G.; Bartlett, Perry F.; Vaidya, Vidita A.

2014-01-01

Norepinephrine regulates latent neural stem cell activity and adult hippocampal neurogenesis, and has an important role in modulating hippocampal functions such as learning, memory and mood. Adult hippocampal neurogenesis is a multi-stage process, spanning from the activation and proliferation of hippocampal stem cells, to their differentiation into neurons. However, the stage-specific effects of noradrenergic receptors in regulating adult hippocampal neurogenesis remain poorly understood. In this study, we used transgenic Nestin-GFP mice and neurosphere assays to show that modulation of α2- and β-adrenergic receptor activity directly affects Nestin-GFP/GFAP-positive precursor cell population albeit in an opposing fashion. While selective stimulation of α2-adrenergic receptors decreases precursor cell activation, proliferation and immature neuron number, stimulation of β-adrenergic receptors activates the quiescent precursor pool and enhances their proliferation in the adult hippocampus. Furthermore, our data indicate no major role for α1-adrenergic receptors, as we did not observe any change in either the activation and proliferation of hippocampal precursors following selective stimulation or blockade of α1-adrenergic receptors. Taken together, our data suggest that under physiological as well as under conditions that lead to enhanced norepinephrine release, the balance between α2- and β-adrenergic receptor activity regulates precursor cell activity and hippocampal neurogenesis. PMID:24922313

Pharmacological effects of saw palmetto extract in the lower urinary tract.

PubMed

Suzuki, Mayumi; Ito, Yoshihiko; Fujino, Tomomi; Abe, Masayuki; Umegaki, Keizo; Onoue, Satomi; Noguchi, Hiroshi; Yamada, Shizuo

2009-03-01

Saw palmetto extract (SPE), an extract from the ripe berries of the American dwarf palm, has been widely used as a therapeutic remedy for urinary dysfunction due to benign prostatic hyperplasia (BPH) in Europe. Numerous mechanisms of action have been proposed for SPE, including the inhibition of 5alpha-reductase. Today, alpha(1)-adrenoceptor antagonists and muscarinic cholinoceptor antagonists are commonly used in the treatment of men with voiding symptoms secondary to BPH. The improvement of voiding symptoms in patients taking SPE may arise from its binding to pharmacologically relevant receptors in the lower urinary tract, such as alpha(1)-adrenoceptors, muscarinic cholinoceptors, 1,4-dihyropyridine receptors and vanilloid receptors. Furthermore, oral administration of SPE has been shown to attenuate the up-regulation of alpha(1)-adrenoceptors in the rat prostate induced by testosterone. Thus, SPE at clinically relevant doses may exert a direct effect on the pharmacological receptors in the lower urinary tract, thereby improving urinary dysfunction in patients with BPH and an overactive bladder. SPE does not have interactions with co-administered drugs or serious adverse events in blood biochemical parameters, suggestive of its relative safety, even with long-term intake. Clinical trials (placebo-controlled and active-controlled trials) of SPE conducted in men with BPH were also reviewed. This review should contribute to the understanding of the pharmacological effects of SPE in the treatment of patients with BPH and associated lower urinary tract symptoms (LUTS).

Drug discrimination and neurochemical studies in alpha7 null mutant mice: tests for the role of nicotinic alpha7 receptors in dopamine release.

PubMed

Quarta, Davide; Naylor, Christopher G; Barik, Jacques; Fernandes, Cathy; Wonnacott, Susan; Stolerman, Ian P

2009-04-01

The nicotine discriminative stimulus has been linked to beta2-containing (beta2*) nicotinic receptors, with little evidence of a role for alpha7 nicotinic receptors, because nicotine discrimination was very weak in beta2 null mutant mice but normal in alpha7 mutants. As both alpha7 and beta2* nicotinic receptors have been implicated in nicotine-stimulated dopamine overflow, this study focused on the dopamine-mediated element in the nicotine stimulus by examining cross-generalisation between amphetamine and nicotine. Male alpha7 nicotinic receptor null mutant mice and wild-type controls were bred in-house and trained to discriminate nicotine (0.8 mg/kg) or (+)-amphetamine (0.6 mg/kg) from saline in a two-lever procedure with a tandem VI-30 FR-10 schedule of food reinforcement. Dopamine release from striatal slices was determined in parallel experiments. An alpha7 nicotinic receptor-mediated component of dopamine release was demonstrated in tissue from wild-type mice using choline as a selective agonist. This response was absent in tissue from null mutant animals. The mutation did not influence acquisition of drug discriminations but subtly affected the results of cross-generalisation tests. In mice trained to discriminate nicotine or amphetamine, there was partial cross-generalisation in wild-type mice and, at certain doses, these effects were attenuated in mutants. Further support for an alpha7 nicotinic receptor-mediated component was provided by the ability of the alpha7 nicotinic receptor antagonist methyllycaconitine to attenuate responses to nicotine and amphetamine in wild-type mice. These findings support the concept of an alpha7 nicotinic receptor-mediated dopaminergic element in nicotine discrimination, warranting further tests with selective dopamine agonists.

Relaxations of the isolated portal vein of the rabbit induced by nicotine and electrical stimulation

PubMed Central

Hughes, J.; Vane, J. R.

1970-01-01

1. A pharmacological analysis of the inhibitory innervation of the isolated portal vein of the rabbit has been made. 2. In untreated preparations, transmural stimulation elicited a long-lasting relaxation at low frequencies (0·2-1 Hz); at higher frequencies a contraction followed by a prolonged after-relaxation occurred. Tetrodotoxin abolished the contractions but a higher dose was required to abolish the relaxations. Veratrine lowered the threshold of stimulation for producing relaxations in the untreated vein. The relaxations were unaffected by hyoscine or hexamethonium. They were reduced or altered by antagonists of α-adrenoceptors for catecholamines and by adrenergic neurone blockade. They were sometimes slightly reduced by antagonists of β-adrenoceptors. 3. In the presence of antagonists of α-adrenoceptors, electrical stimulation elicited relaxations which increased with frequency of stimulation and became maximal at 20-30 Hz. These relaxations were partially reduced by antagonists of β-adrenoceptors, or by adrenergic neurone block; the antagonisms were more pronounced at the higher frequencies of stimulation. Noradrenaline also caused relaxations which were abolished by β-adrenoceptor blocking drugs. Cocaine increased the sensitivity to noradrenaline by 7-8 fold after α-adrenoceptor blockade but had little or no effect on the relaxations induced by electrical stimulation at high frequencies. 4. In the presence of antagonists of α- and β-adrenoceptors, or adrenergic neurone blocking agents, or in veins taken from rabbits pretreated with reserpine, electrical stimulation elicited rapid relaxations which were greatest at 20-30 Hz. These relaxations were increased by veratrine and abolished by tetrodotoxin or by storing the vein for 9 days at 4° C. They were unaffected by antagonists of acetylcholine, or by dipyridamole. 5. Prostaglandins E1, E2 and F2α inhibited contractions elicited by electrical stimulation and noradrenaline, but in higher doses caused contractions themselves. 6. Nicotine (10-6-10-5 g/ml) relaxed the portal vein; higher concentrations elicited mixed inhibitory and excitatory effects. All these effects were abolished by tetrodotoxin, cocaine, hexamethonium or storage. The contractor effects were abolished by drugs or procedures that blocked adrenergic mechanisms. 7. The relaxations produced by nicotine in untreated preparations and in veins from rabbits pretreated with reserpine were mediated mainly by a non-adrenergic non-cholinergic nervous mechanism. Relaxations induced by nicotine in the presence of antagonists of a-adrenoceptors were only partially antagonized by antagonists of f3-adrenoceptors. 8. It was concluded that all the effects of nicotine and transmural stimulation were mediated by nerves. Part of the inhibitory effects was mediated by non-adrenergic, non-cholinergic nerves. PMID:4394338

Opioid Dependence Treatment: Options In Pharmacotherapy

PubMed Central

Stotts, Angela L.; Dodrill, Carrie L.; Kosten, Thomas R.

2010-01-01

The development of effective treatments for opioid dependence is of great importance given the devastating consequences of the disease. Pharmacotherapies for opioid addiction include opioid agonists, partial agonists, opioid antagonists, and alpha-2-adrenergic agonists, which are targeted toward either detoxification or long-term agonist maintenance. Agonist maintenance therapy is currently the recommended treatment for opioid dependence due to its superior outcomes relative to detoxification. Detoxification protocols have limited long term efficacy and patient discomfort remains a significant therapy challenge. Buprenorphine’s effectiveness relative to methadone remains a controversy and may be most appropriate for patients in need of low doses of agonist treatment. Buprenorphine appears superior to alpha-2 agonists, however, and office-based treatment with buprenorphine in the US is gaining support. Studies of sustained-release formulations of naltrexone suggest improved effectiveness for retention and sustained abstinence, however, randomized clinical trials are needed. PMID:19538000

Immortalization of cat iris sphincter smooth muscle cells by SV40 virus: growth, morphological, biochemical and pharmacological characteristics.

PubMed

Ocklind, A; Yousufzai, S Y; Ghosh, S; Coca-Prados, M; St Jernschantz, J; Abdel-Latif, A A

1995-11-01

The purpose of this study was to establish immortalized cell cultures of cat iris sphincter smooth muscle cells for a model investigating ocular receptors and their signal transduction pathways. Cultured cat iris sphincter muscle cells were immortalized by viral transformation with SV40 virus and the morphological and immunocytochemical properties of the normal and immortalized cells were investigated. The transformed cell clone, SV-CISM-2, was further characterized biochemically and pharmacologically. The normal muscle cells showed characteristics of smooth muscle cells, as judged by their growth and the presence of smooth muscle alpha-actin and desmin. After seven passages the normal cells ceased to proliferate. In contrast, the immortalized cells retained their proliferative ability for more than 220 population doublings over 55 passages. The transformation phenotype in these cells was confirmed by their expression of the large T-antigen, the incorporation of viral DNA into cellular DNA, growth in agarose and in low-serum medium, and complete loss of contact inhibition. The immortalized cells expressed smooth muscle alpha-actin, desmin and MLC protein. Biochemical and pharmacological studies on the SV-CISM cells revealed the presence of several functional receptors including muscarinic cholinergic, beta-adrenergic, peptidergic (substance P and endothelin). Platelet-activating factor, and prostaglandin (PG). Muscarinic stimulation of these cells resulted in: (a) a dose-dependent increase in the release of arachidonic acid (AA) and (PGs) and enhancement in the production of inositol trisphosphate (IP3); and (b) a substantial increase in MLC phosphorylation (118%), an indicator of smooth muscle contractility. The stimulatory effects of carbachol on these responses were completely blocked by atropine, a muscarinic receptor antagonist. This study constitutes the first successful immortalization of iris sphincter smooth muscle cells. The SV-CISM-2 cells can serve as an important model system for investigations on the biochemical and pharmacological properties of receptors and their signal transduction pathways in smooth muscle. The advantage of these cells over normal iris sphincter cells is that they can be propagated over many generations without alterations in their morphological, biochemical and physiological characteristics.

Antidepressant-like effect of the organoselenium compound ebselen in mice: evidence for the involvement of the monoaminergic system.

PubMed

Posser, Thaís; Kaster, Manuella P; Baraúna, Sara Cristiane; Rocha, João B T; Rodrigues, Ana Lúcia S; Leal, Rodrigo B

2009-01-05

Ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one] is a seleno-organic compound which possesses a potent antioxidant activity and has been shown to exert neuroprotective effects in vitro and in vivo in a variety of pro-oxidative insults. The present study investigates a possible antidepressant activity of ebselen using two predictive tests for antidepressant activity in rodents: the forced swimming test and tail suspension test. Additionally, the mechanisms involved in the antidepressant-like effect of ebselen in mice were also assessed. Ebselen (10 mg/kg, s.c.) decreased the immobility time in the forced swimming test without accompanying changes in ambulation in the open-field test. In contrast, the administration of ebselen (10-30 mg/kg) did not produce any effect in the tail suspension test. The anti-immobility effect of ebselen (10 mg/kg, s.c.) was not prevented by pre-treatment of mice with p-chlorophenylalanine (PCPA, 100 mg/kg, i.p., an inhibitor of serotonin synthesis, 4 consecutive days), NAN-190 (0.5 mg/kg, i.p., a serotonin 5-HT(1A) receptor antagonist) or ketanserin (5 mg/kg, i.p., a serotonin 5-HT(2A/2C) receptor antagonist). On the other hand, the pre-treatment of mice with prazosin (1 mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., a dopamine D(1) receptor antagonist) or sulpiride (50 mg/kg, i.p., a dopamine D(2) receptor antagonist) completely blocked the antidepressant-like effect of ebselen (10 mg/kg, s.c.) in the forced swimming test. It may be concluded that ebselen produces an antidepressant-like effect in the forced swimming test that seems to be dependent on its interaction with the noradrenergic and dopaminergic systems, but not with the serotonergic system.

Investigating β-adrenergic-induced cardiac hypertrophy through computational approach: classical and non-classical pathways.

PubMed

Khalilimeybodi, Ali; Daneshmehr, Alireza; Sharif-Kashani, Babak

2018-07-01

The chronic stimulation of β-adrenergic receptors plays a crucial role in cardiac hypertrophy and its progression to heart failure. In β-adrenergic signaling, in addition to the well-established classical pathway, Gs/AC/cAMP/PKA, activation of non-classical pathways such as Gi/PI3K/Akt/GSK3β and Gi/Ras/Raf/MEK/ERK contribute in cardiac hypertrophy. The signaling network of β-adrenergic-induced hypertrophy is very complex and not fully understood. So, we use a computational approach to investigate the dynamic response and contribution of β-adrenergic mediators in cardiac hypertrophy. The proposed computational model provides insights into the effects of β-adrenergic classical and non-classical pathways on the activity of hypertrophic transcription factors CREB and GATA4. The results illustrate that the model captures the dynamics of the main signaling mediators and reproduces the experimental observations well. The results also show that despite the low portion of β2 receptors out of total cardiac β-adrenergic receptors, their contribution in the activation of hypertrophic mediators and regulation of β-adrenergic-induced hypertrophy is noticeable and variations in β1/β2 receptors ratio greatly affect the ISO-induced hypertrophic response. The model results illustrate that GSK3β deactivation after β-adrenergic receptor stimulation has a major influence on CREB and GATA4 activation and consequent cardiac hypertrophy. Also, it is found through sensitivity analysis that PKB (Akt) activation has both pro-hypertrophic and anti-hypertrophic effects in β-adrenergic signaling.

[The mechanism of change in speed of agglutination of human erythrocytes under the influence of adrenaline].

PubMed

Volodchenko, A I; Tsirkin, V I; Kostiaev, A A

2014-01-01

In the study of red blood cells of 80 men found that adrenaline (10(-10) - 10(-6) g/mL) and phenylephrine (10-(10) - 10(-6) g/mL) dose-dependently increase the speed of agglutination of red blood cells, according to the decrease in agglutination of the start time and ginipral (10(-10) - 10(-7) g/mL), on the contrary, decreases it. The effect of adrenaline and phenylephrine is blocked by nicergoline (10(-6) g/mL), increased obzidan (10(-6) g/mL) and does not change under the action ofyohimbine (10(-6) g/mL) and atenolol (10(-6) g/mL). These data indicate that the speed of agglutination increases with activation alpha1-adrenergic receptor (AR) and decreases in the activation of beta2-AR, while the activation of alpha2- and beta1-AR does not affect it. Trifluoperazine (10(-6) g/mL) as the calmodulin antagonist, barium chloride (10(-6) g/mL) as a blocked of Ca(2+)-dependent K(+)-channels and indomethacine (10(-6) g/mL) as an inhibitor of cyclooxygenase and phospholipase A2 inhibit the ability of adrenaline to increases the speed of agglutination of red blood cells. This suggests that the effect of adrenaline caused an increase in erythrocyte entry of Ca2+, activation of calmodulin, cyclooxygenase, phospholipase A2 and the release of K+ from red blood cell through the Ca(2+)-dependent K+ channels, which is regarded as a manifestation of eryptosis. Indirectly, this means that more efficient activation of alpha1-AR and beta2-AR, respectively, increases or, conversely, decreases the rate of eryptosis.

Antinociceptive activity of methanolic extract of Muntingia calabura leaves: further elucidation of the possible mechanisms

PubMed Central

2014-01-01

Background Muntingia calabura (Elaecoparceae) is a medicinal plant traditionally used, particularly, by the Peruvian people to alleviate headache and cold, pain associated with gastric ulcers or to reduce the prostate gland swelling. Following the recent establishment of antinociceptive activity of M. calabura leaf, the present study was performed to further elucidate on the possible mechanisms of antinociception involved. Methods The methanol extract of M. calabura (MEMC) was prepared in the doses of 100, 250 and 500 mg/kg. The role of bradykinin, protein kinase C, pottasium channels, and various opioid and non-opioid receptors in modulating the extract’s antinociceptive activity was determined using several antinociceptive assays. Results are presented as Mean ± standard error of mean (SEM). The one-way ANOVA test with Dunnett's multiple comparison was used to analyze and compare the data, with P < 0.05 as the limit of significance. Results The MEMC, at all doses, demonstrated a significant (p < 0.05) dose-dependent antinociceptive activity in both the bradykinin- and phorbol 12-myristate 13-acetate (PMA)-induced nociception. Pretreatment of the 500 mg/kg MEMC with 10 mg/kg glibenclamide (an ATP-sensitive K+ channel inhibitor), the antagonist of μ-, δ- and κ-opioid receptors (namely 10 mg/kg β-funaltrexamine, 1 mg/kg naltrindole and 1 mg/kg nor-binaltorphimine), and the non-opioid receptor antagonists (namely 3 mg/kg caffeine (a non-selective adenosinergic receptor antagonist), 0.15 mg/kg yohimbine (an α2-noradrenergic antagonist), and 1 mg/kg pindolol (a β-adrenoceptor antagonist)) significantly (p < 0.05) reversed the MEMC antinociception. However, 10 mg/kg atropine (a non-selective cholinergic receptor antagonist), 0.15 mg/kg prazosin (an α1-noradrenergic antagonist) and 20 mg/kg haloperidol (a non-selective dopaminergic antagonist) did not affect the extract's antinociception. The phytochemicals screening revealed the presence of saponins, flavonoids, tannins and triterpenes while the HPLC analysis showed the presence of flavonoid-based compounds. Conclusions The antinociceptive activity of MEMC involved activation of the non-selective opioid (particularly the μ-, δ- and κ-opioid) and non-opioid (particularly adenosinergic, α2-noradrenergic, and β-adrenergic) receptors, modulation of the ATP-sensitive K+ channel, and inhibition of bradikinin and protein kinase C actions. The discrepancies in MEMC antinociception could be due to the presence of various phytochemicals. PMID:24555641

Selective stimulation and blockade of beta-adrenergic receptors in the mandibular gland of the red kangaroo, Macropus rufus.

PubMed

Beal, A M

2000-12-01

Intracarotid infusions of noradrenaline (0.15 nmol x kg(-1) x min(-1)) either alone or accompanied by phentolamine (1.5 nmol x kg(-1) x min(-1)) caused similar-sized increases in salivary protein, magnesium and bicarbonate, and decreases in osmolality, sodium, potassium and chloride whereas intravenous noradrenaline stimulated much smaller responses. Concurrent infusions of the beta1-antagonist, CGP20712A, blocked these noradrenaline-induced changes in salivary composition more effectively than equimolar infusions of the beta2-antagonist, ICI118551, thereby confirming the presence of beta1-adrenoceptors. Intracarotid infusion of salbutamol at 0.15, 0.3 and 1.5 nmol x kg(-1) x min(-1) caused increasing but qualitatively similar changes in salivary composition, sodium excepted, to intracarotid noradrenaline with 0.3 nmol being most similar quantitatively. Intravenous infusion of salbutamol caused larger changes in salivary composition than equimolar intravenous noradrenaline thereby indicating that the response to salbutamol may, in part, be mediated by reflex increases in general sympathetic tone triggered by lowered blood pressure. Eliminating this hypotensive effect by concurrent intravenous and intracarotid infusions of beta1-(CGP or atenolol) and beta2-(ICII18551) antagonists with intracarotid salbutamol showed that IC1118551 was more potent than the beta1-antagonists thereby demonstrating the presence of beta2-receptors. It was concluded that the kangaroo mandibular has functional beta1- and beta2-adrenoceptor subtypes in both endpieces and excurrent ducts and that the duct system has two populations of cells, each expressing one receptor subtype.

Serotonin-1A receptors in the dorsal periaqueductal gray matter mediate the panicolytic-like effect of pindolol and paroxetine combination in the elevated T-maze.

PubMed

Sela, Vânia Ramos; Biesdorf, Carla; Ramos, Diego Henrique; Zangrossi, Hélio; Graeff, Frederico Guilherme; Audi, Elisabeth Aparecida

2011-05-09

The β-adrenergic blocker and 5-HT(1A) receptor antagonist pindolol has been combined with selective serotonin reuptake inhibitors (SSRIs) in patients with depressive and anxiety disorders to shorten the onset of the clinical action and/or increase the proportion of responders. The results of a previous study have shown that pindolol potentiates the panicolytic effect of paroxetine in rats submitted to the elevated T-maze (ETM). Since reported evidence has implicated the 5-HT(1A) receptors of the dorsal periaqueductal gray matter (DPAG) in the panicolytic effect of antidepressants, rats treated with pindolol (5.0mg/kg, i.p.) and paroxetine (1.5mg/kg, i.p.) received a previous intra-DPAG injection of the selective 5-HT(1A) antagonist, WAY-100635 (0.4 μg) and were submitted to the ETM. Pretreatment with WAY-100635 reversed the increase in escape latency, a panicolytic effect, determined by the pindolol-paroxetine combination. These results implicate the 5-HT(1A) receptors of the DPAG in the panicolytic effect of the pindolol-paroxetine combination administered systemically. They also give further preclinical support for the use of this drug combination in the treatment of panic disorder. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.