beta-Adrenoceptor agonists enhance 5-hydroxytryptamine-mediated behavioural responses.

PubMed Central

Cowen, P. J.; Grahame-Smith, D. G.; Green, A. R.; Heal, D. J.

1982-01-01

The beta-adrenoceptor agonists, salbutamol, terbutaline and clenbuterol, were investigated for their effect on 5-hydroxytryptamine-mediated (5-HT) hyperactivity. 2 The lipophilic beta-adrenoceptor agonist, clenbuterol (5 mg/kg) enhanced the behaviours induced by quipazine (25 mg/kg), including headweaving, forepaw treading and hind-limb abduction and thus increased automated activity recording. Clenbuterol (5 mg/kg) also enhanced the hyperactivity syndrome produced by the 5-HT agonist, 5-methoxy N,N-dimethyltryptamine (2 mg/kg) and the combination of tranylcypromine (10 mg/kg) and L-tryptophan (50 mg/kg). Salbutamol and terbutaline potentiated quipazine-induced hyperactivity only when given at the higher dose of 20 mg/kg. 3 The effect of clenbuterol in enhancing quipazine hyperactivity was blocked by the centrally acting beta 1-adrenoceptor antagonist, metoprolol (5 mg/kg), but not by the beta 2-adrenoceptor antagonist, butoxamine (5 mg/kg) or the peripherally acting beta 1-adrenoceptor antagonist, atenolol (5 mg/kg). 4 Clenbuterol (5 mg/kg) did not enhance the circling responses produced by methamphetamine (0.5 mg/kg) in unilateral nigrostriatal-lesioned rats. 5 The results suggest that beta-adrenoceptor agonists in common with some established antidepressant treatments produce enhancement of 5-HT-mediated behavioural responses. PMID:6124294

Beta 2-agonist fenoterol has greater effects on contractile function of rat skeletal muscles than clenbuterol.

PubMed

Ryall, James G; Gregorevic, Paul; Plant, David R; Sillence, Martin N; Lynch, Gordon S

2002-12-01

Potential treatments for skeletal muscle wasting and weakness ideally possess both anabolic and ergogenic properties. Although the beta(2)-adrenoceptor agonist clenbuterol has well-characterized effects on skeletal muscle, less is known about the therapeutic potential of the related beta(2)-adrenoceptor agonist fenoterol. We administered an equimolar dose of either clenbuterol or fenoterol to rats for 4 wk to compare their effects on skeletal muscle and tested the hypothesis that fenoterol would produce more powerful anabolic and ergogenic effects. Clenbuterol treatment increased fiber cross-sectional area (CSA) by 6% and maximal isometric force (P(o)) by 20% in extensor digitorum longus (EDL) muscles, whereas fiber CSA in soleus muscles decreased by 3% and P(o) was unchanged, compared with untreated controls. In the EDL muscles, fenoterol treatment increased fiber CSA by 20% and increased P(o) by 12% above values achieved after clenbuterol treatment. Soleus muscles of fenoterol-treated rats exhibited a 13% increase in fiber CSA and a 17% increase in P(o) above that of clenbuterol-treated rats. These data indicate that fenoterol has greater effects on the functional properties of rat skeletal muscles than clenbuterol.

[Oral tocolytic therapy with clenbuterol--clinical facts].

PubMed

Meinen, K; Rahn, M; Hermer, M; Rominger, K L; Kanitz, T

1988-01-01

Clenbuterol is a betamimetic agent with a marked effect on the adrenergic beta-2-receptors relevant for tocolysis. The influence on beta-1-receptors of the heart, resulting in cardiovascular side effects is far less. The substance is resorbed almost completely enterally and has a half-life of 34 hours. Consequently, ingestion intervals of 12 hours are possible, resulting in a good acceptance of the tocolytic, therapy and a noticeable improvement of the patients compliance. Clenbuterol was applied in 37 cases in the course of a clinical test. Initially, the dose was 0.04 mg b.i.d., after 24 hours 0.02 mg b.i.d. In cases of cervix-effective, premature labor, an objectively measureable tocolytic effect was achieved. Subjectively reported side effects, i.e. palpation, tachycardia and tremor, were noticeably weaker than under fenoterol therapy. There was no indication of clenbuterol-related cardiotoxicity regarding continuous measurement of heart-specific enzymes, i.e. CK-MB and serum myoglobin. No pathologic alterations were found in the EKGs. Therefore, regarding indications and contraindications for beta-adrenergic agents, clenbuterol appears to have good tocolytic properties, with the advantages of less cardiac side effects, better compliance and a better dose-effect-ratio compared with the common oral tocolysis with fenoterol.

Development of protein A functionalized microcantilever immunosensors for the analyses of small molecules at parts per trillion levels.

PubMed

Tan, Weiming; Huang, Yuan; Nan, Tiegui; Xue, Changguo; Li, Zhaohu; Zhang, Qingchuan; Wang, Baomin

2010-01-15

Development of microcantilever biosensors for small molecules was exemplified with the beta-adrenergic agonist clenbuterol and the antibiotic chloramphenicol. In this paper, antibody sulfhydrylation and protein A were used to modify the microcantilever Au surface, and the antibody activities on the microcantilever were evaluated with direct competitive enzyme-linked immunosorbent assay (dcELISA). The activity of the antibodies immobilized on the microcantilever via protein A was 1.7-fold of that via the sulfhydrylation reagent 2-iminothiolane hydrochloride. A microcantilever immunosensor method with protein A as the functionalization reagent was established to detect the residues of clenbuterol and chloramphenicol at limits of detection (LOD) of approximately 0.1 and 0.2 ng/mL, respectively. Such LODs were better than that of the corresponding dcELISAs. The concentration of clenbuterol in a fortified feed sample detected with the microcantilever immunosensor after thorough extraction and purification agreed well with that detected with the dcELISA. Protein A showed to be simple and reproducible for functionalization of the antibodies on the Au surface and, thus, has common application values in microcantilever immunosensor development. The results suggest that microcantilever immunosensors be suitable for detection of small molecules, and the assay sensitivity is mainly related to the quality and activities of the antibodies.

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

β2-Adrenoceptors and non-β-adrenoceptors mediate effects of BRL37344 and clenbuterol on glucose uptake in soleus muscle: studies using knockout mice

PubMed Central

Ngala, Robert A; O'Dowd, Jacqueline; Wang, Steven J; Stocker, Claire; Cawthorne, Michael A; Arch, Jonathan RS

2009-01-01

Background and purpose: In previous work, 10 pM BRL37344 and 10 pM clenbuterol stimulated glucose uptake in mouse soleus muscle. Ten nM BRL37344 also stimulated uptake but 100 nM clenbuterol inhibited uptake. Antagonist studies suggested that the opposite effects of 10 nM BRL37344 and 100 nM clenbuterol are mediated by the β2-adrenoceptor. BRL37344 and clenbuterol have been studied in muscles that lack β3-, β2- or all three β-adrenoceptors. Effects of β-adrenoceptor antagonists on responses to the agonists have been studied further using muscles from wild-type mice. Experimental approach: Soleus muscles of wild-type or β-adrenoceptor knockout mice were incubated with 2-deoxy[1-14C]-glucose, and β-adrenoceptor ligands. Formation of 2-deoxy[1-14C]-glucose-6-phosphate was measured. Key results: Concentration–response relationships were similar for BRL37344 and clenbuterol in normal muscle and muscle lacking β3-adrenoceptors. Ten pM BRL37344 and clenbuterol stimulated glucose uptake in muscle lacking β2-adrenoceptors or all three β-adrenoceptors, but 10 nM BRL37344 did not stimulate uptake in either case, and 100 nM clenbuterol stimulated, rather than inhibited, uptake in muscle lacking β2-adrenoceptors. One hundred nM clenbuterol also stimulated glucose uptake in normal muscle when β2-adrenoceptors were blocked with ICI118551, and this was not prevented by antagonism of β1- or β3-adrenoceptors. Conclusions and implications: Ten nM BRL37344 and 100 nM clenbuterol have opposite effects on glucose uptake but both effects are mediated by the β2-adrenoceptor – apparently an example of agonist-directed signalling. Ten pM BRL37344, 10 pM clenbuterol and 100 nM clenbuterol in the presence of ICI118551 stimulate glucose uptake via β-adrenoceptor-independent mechanisms, demonstrating unknown properties for the agonists. PMID:19912225

Development of an immunochromatographic assay for the β-adrenergic agonist feed additive zilpaterol.

PubMed

Shelver, Weilin L; Smith, David J

2018-06-06

Zilpaterol is a β-adrenergic agonist feed additive approved in the United States to increase weight gain and improve feed efficiency of cattle. A zilpaterol immunochromatographic assay was developed as an economical and user-friendly rapid detection method for zilpaterol and validated using urine and tissue samples derived from animal studies. The assay sensitivity was 1.7-23.2 ng g -1 or mL -1 across a variety of feed and animal matrices and did not cross-react with clenbuterol or ractopamine. No sample pre-treatment of cattle and sheep urine was needed, but horse urine and feed required dilution; skeletal muscle required solvent extraction prior to testing. Of 32 incurred sheep urine samples tested, zilpaterol content was correctly identified in all but 2 samples. Horse urine containing >10 ng mL -1 of incurred zilpaterol residue (n = 48) was correctly identified as zilpaterol positive. The assay correctly identified 0-day withdrawal sheep muscle samples as zilpaterol positive and the control and longer withdrawal day sheep muscle samples as negative. Zilpaterol was demonstrated to be stable in horse urine when stored at -20°C for 7 years.

Investigation on potential enzyme toxicity of clenbuterol to trypsin

NASA Astrophysics Data System (ADS)

Chai, Jun; Xu, Qifei; Dai, Jinping; Liu, Rutao

2013-03-01

Clenbuterol (CLB) is a kind of β2-adrenergic agonists which was illegally used as feed additives nowadays. The toxic interaction of CLB with trypsin, an important digestive enzyme, was studied in vitro using multi-spectroscopic methods and molecular modeling methods. CLB was proved to bind with trypsin in S1 pocket, forming a complex driven by the dominant force of H-bond. The binding constant was calculated to be 1.79887 × 105 L mol-1 at 289 K and 0.32584 × 105 L mol-1 at 310 K, respectively. The skeleton of trypsin became loosened and unfolded with the amino residues microenvironment changed. The secondary and tertiary structure of trypsin also varied. Molecular modeling studies illustrated specific display of the binding information and explained most of the experiment phenomena. The binding site of CLB induced the fluorescence quenching as well as inhibition of enzyme activity of trypsin. The study confirmed that CLB had potential toxicity on both the structure and function of trypsin and the effects enhanced with the increasing concentration of CLB.

Clenbuterol, a beta(2)-agonist, retards atrophy in denervated muscles

NASA Technical Reports Server (NTRS)

Zeman, Richard J.; Ludemann, Robert; Etlinger, Joseph D.

1987-01-01

The effects of a beta(2) agonist, clenbuterol, on the protein content as well as on the contractile strength and the muscle fiber cross-sectional area of various denervated muscles from rats were investigated. It was found that denervated soleus, anterior tibialis, and gastrocnemius muscles, but not the extensor digitorum longus, of rats treated for 2-3 weeks with clenbuterol contained 95-110 percent more protein than denervated controls. The twofold difference in the protein content of denervated solei was paralleled by similar changes in contractile strength and muscle fiber cross-sectional area.

Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy.

PubMed

Woodall, Benjamin P; Woodall, Meryl C; Luongo, Timothy S; Grisanti, Laurel A; Tilley, Douglas G; Elrod, John W; Koch, Walter J

2016-10-14

GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2 fl/fl ) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2 fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β 2 -adrenergic receptor (β 2 AR) agonist, was significantly enhanced in MLC-Cre:GRK2 fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β 2 AR-induced hypertrophy. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Metabolic responses to BRL37344 and clenbuterol in soleus muscle and C2C12 cells via different atypical pharmacologies and β2-adrenoceptor mechanisms

PubMed Central

Ngala, R A; O'Dowd, J; Wang, S J; Agarwal, A; Stocker, C; Cawthorne, M A; Arch, J R S

2008-01-01

Background and purpose: Picomolar concentrations of the β3-adrenoceptor agonist BRL37344 stimulate 2-deoxyglucose uptake in soleus muscle via undefined receptors. Higher concentrations alter uptake, apparently via β2-adrenoceptors. Effects of BRL37344 and β2-adrenoceptor agonists are compared. Experimental approach: Mouse soleus muscles were incubated with 2-deoxy[1-14C]-glucose, [1-14C]-palmitate or [2-14C]-pyruvate, and BRL37344, β2-adrenoceptor agonists and selective β-adrenoceptor antagonists. Formation of 2-deoxy[1-14C]-glucose-6-phosphate or 14CO2 was measured. 2-Deoxy[1-14C]-glucose uptake and β-adrenoceptor mRNA were measured in C2C12 cells. Key results: 10 pM BRL37344, 10 pM clenbuterol and 100 pM salbutamol stimulated 2-deoxyglucose uptake in soleus muscle by 33–54%. The effect of BRL37344 was prevented by 1 μM atenolol but not by 300 nM CGP20712A or IC3118551, or 1 μM SR59230A; that of clenbuterol was prevented by ICI118551 but not atenolol. 10 nM BRL37344 st4mulated 2-deoxyglucose uptake, whereas 100 nM clenbuterol and salbutamol inhibited uptake. These effects were blocked by ICI118551. Similar results were obtained in C2C12 cells, in which only β2-adrenoceptor mRNA could be detected by RT-PCR. 10 nM BRL37344 and 10 pM clenbuterol stimulated muscle palmitate oxidation. In the presence of palmitate, BRL37344 no longer stimulated 2-deoxyglucose uptake and the effect of clenbuterol was not significant. Conclusions and implications: Stimulation of glucose uptake by 10 pM BRL37344 and clenbuterol involves different atypical pharmacologies. Nanomolar concentrations of BRL37344 and clenbuterol, probably acting via β2-adrenoceptors, have opposite effects on glucose uptake. The agonists preferentially stimulate fat rather than carbohydrate oxidation, but stimulation of endogenous fat oxidation cannot explain why 100 nM clenbuterol inhibited 2-deoxyglucose uptake. PMID:18552870

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.

Slow to fast alterations in skeletal muscle fibers caused by clenbuterol, a beta(2)-receptor agonist

NASA Technical Reports Server (NTRS)

Zeman, Richard J.; Ludemann, Robert; Easton, Thomas G.; Etlinger, Joseph D.

1988-01-01

The effects of a beta(2)-receptor agonist, clenbuterol, and a beta(2) antagonist, butoxamine, on the skeletal muscle fibers of rats were investigated. It was found that chronic treatment of rats with clenbuterol caused hypertrophy of histochemically identified fast-twitch, but not slow-twitch, fibers within the soleus, while in the extensor digitorum longus the mean areas of both fiber types were increased; in both muscles, the ratio of the number of fast-twitch to slow-twitch fibers was increased. In contrast, a treatment with butoxamine caused a reduction of the fast-twitch fiber size in both muscles, and the ratio of the fast-twitch to slow-twitch fibers was decreased.

Clenbuterol storage stability in the bovine urine and liver samples used for European official control in the azores islands (portugal).

PubMed

Pinheiro, Isabel; Jesuino, Bruno; Barbosa, Jorge; Ferreira, Humberto; Ramos, Fernando; Matos, José; da Silveira, Maria Irene Noronha

2009-02-11

Clenbuterol is a well-known growth promoter, illegally used in farm animals, especially in cattle. Samples collected for the screening of beta(2)-agonist residues in Portuguese Azores Islands must travel through all the nine islands until they reach Azores Central Laboratory. If any suspicious sample is detected, it must be further transported to the National Reference Laboratory in Lisbon for confirmation. As a consequence of these circumstances, samples are submitted to different transport and storage times, as well as different temperature conditions and in some cases successive freezing and thawing cycles. As clenbuterol is the most detected beta(2)-agonist growth promoter in the Portuguese Residue Monitoring Plan, studies were conducted on the stability of this compound in incurred samples (bovine liver and urine) at +4, -20 and -60 degrees C over time. Samples kept at -20 degrees C were also analyzed over time after successive freezing and thawing cycles. The analyses of clenbuterol over time were performed by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). Clenbuterol in incurred urine and liver samples was significantly stable up to 20 weeks at -20 and -60 degrees C and after, at least, six consecutive freezings and thawings. At +4 degrees C, clenbuterol remained stable, at least until 12 weeks in urine and up to 20 weeks in liver.

Effect of Serum from Chickens Treated with Clenbuterol on Myosin Accumulation, Beta-Adrenergic Receptor Population, and Cyclic AMP Synthesis in Embryonic Chicken Skeletal Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, Kristin Y.; Wuethrich, Andrew J.; Hancock, Deana L.

2002-01-01

Broiler chickens at 35 d of age were fed 1 ppm clenbuterol for 14 d. This level of dietary clenbuterol led to 5-7% increases in the weights of leg and breast muscle tissue. At the end of the 14-d period, serum was prepared from both control and clenbuterol-treated chickens, and was then employed as a component of cell culture media at a final concentration of 20% (v/v). Muscle cell cultures were prepared from both the leg and the breast muscle groups of 12-d chick embryos. Treatment groups included control chicken serum to which 10 nM, 50 nM, and 1 uM clenbuterol had been added, as well as cells grown in media containing 10% horse serum. Cultures were subjected to each treatment for 3 d, beginning on the seventh d in culture. Neither the percent fusion nor the number of nuclei in myotubes was significantly affected by any of the treatments. The quantity of myosin heavy chains (MHCs) was not increased by serum from clenbuterol-treated chickens in either breast or leg muscle cultures; however, the MHC quantity was 50-150% higher in cultures grown in control chicken serum to which 10 and 50 nM clenbuterol had also been added. The B-adrenergic receptor (betaAR) population was 4000-7000 betaARs per cell in cultures grown in chicken serum with leg muscle cultures having approximately 25-30% more receptors than breast muscle Culture. Receptor population was not significantly affected by the presence of clenbuterol or by the presence of serum from clenbuterol-treated chickens. In contrast, the betaAR Population in leg and breast muscle cultures grown in the presence of 10% horse serum was 16,000-18,000 betaARs per cell. Basal concentration of cyclic adenosine 3':5'monophosphate (cAMP) was not significantly affected by the treatments. When cultures grown in chicken serum were stimulated for 10 min with 1 uM isoproterenol, limited increases of 12-20% in cAMP Concentration above the. basal levels were observed. However, when cultures grown in the presence of horse serum were stimulated with 1 uM isoproterenol, cAMP concentration was stimulated 5- to 9-fold above the basal levels. Thus, not only did cells, grown in horse serum have a higher PAR population, but also each receptor had a higher capacity for cAMP synthesis following isoproterenol stimulation. Finally, the hypothesis that clenbuterol exerts its action on muscle protein content by changes in cAMP concentration was tested. No correlation was apparent between basal cAMP concentration and MHC content.

Mechanisms involved in 3',5'-cyclic adenosine monophosphate-mediated inhibition of the ubiquitin-proteasome system in skeletal muscle.

PubMed

Gonçalves, Dawit A P; Lira, Eduardo C; Baviera, Amanda M; Cao, Peirang; Zanon, Neusa M; Arany, Zoltan; Bedard, Nathalie; Tanksale, Preeti; Wing, Simon S; Lecker, Stewart H; Kettelhut, Isis C; Navegantes, Luiz C C

2009-12-01

Although it is well known that catecholamines inhibit skeletal muscle protein degradation, the molecular underlying mechanism remains unclear. This study was undertaken to investigate the role of beta(2)-adrenoceptors (AR) and cAMP in regulating the ubiquitin-proteasome system (UPS) in skeletal muscle. We report that increased levels of cAMP in isolated muscles, promoted by the cAMP phosphodiesterase inhibitor isobutylmethylxanthine was accompanied by decreased activity of the UPS, levels of ubiquitin-protein conjugates, and expression of atrogin-1, a key ubiquitin-protein ligase involved in muscle atrophy. In cultured myotubes, atrogin-1 induction after dexamethasone treatment was completely prevented by isobutylmethylxanthine. Furthermore, administration of clenbuterol, a selective beta(2)-agonist, to mice increased muscle cAMP levels and suppressed the fasting-induced expression of atrogin-1 and MuRF-1, atrogin-1 mRNA being much more responsive to clenbuterol. Moreover, clenbuterol increased the phosphorylation of muscle Akt and Foxo3a in fasted rats. Similar responses were observed in muscles exposed to dibutyryl-cAMP. The stimulatory effect of clenbuterol on cAMP and Akt was abolished in muscles from beta(2)-AR knockout mice. The suppressive effect of beta(2)-agonist on atrogin-1 was not mediated by PGC-1alpha (peroxisome proliferator-activated receptor-gamma coactivator 1alpha known to be induced by beta(2)-agonists and previously shown to inhibit atrogin-1 expression), because food-deprived PGC-1alpha knockout mice were still sensitive to clenbuterol. These findings suggest that the cAMP increase induced by stimulation of beta(2)-AR in skeletal muscles from fasted mice is possibly the mechanism by which catecholamines suppress atrogin-1 and the UPS, this effect being mediated via phosphorylation of Akt and thus inactivation of Foxo3.

A descriptive study of adverse events from clenbuterol misuse and abuse for weight loss and bodybuilding.

PubMed

Spiller, Henry A; James, Kyla J; Scholzen, Steven; Borys, Douglas J

2013-01-01

Clenbuterol is a β2-agonist approved in the United States for veterinary use in nonfood animals. Clenbuterol use is emerging among bodybuilders and fitness enthusiasts attracted to the hypertrophic and lipolytic effects. This was a retrospective chart review of clenbuterol exposures reported to 2 poison control centers. Misuse of clenbuterol for weight loss and bodybuilding was reported in 11 of 13 clenbuterol users. Reported clinical effects included tachycardia, widened pulse pressure, tachypnea, hypokalemia, hyperglycemia, ST changes on electrocardiogram (ECG), elevated troponin, elevated creatine phosphokinase (CPK), palpitations, chest pain, and tremor. Measured serum clenbuterol concentration was 2983 pg/mL post 4.5 mg ingestion. Co-ingestants included T3 and anabolic steroids. Treatments included activated charcoal, benzodiazepines, β-blockers, potassium replacement, and intravenous (IV) fluid. There is an increasing use of the Internet for illicit drug use for bodybuilding and weight loss purposes. These patients may not present as the stereotype of illicit drug abusers, but as healthy athletic low-risk patients. Clinical effects persisted greater than 24 hours with evidence of myocardial injury in 2 patients. Clenbuterol is increasingly being abused within the bodybuilding subculture. These cases illustrate the hidden dangers of clenbuterol abuse among bodybuilders and fitness enthusiasts.

Effects of chronic administration of clenbuterol on contractile properties and calcium homeostasis in rat extensor digitorum longus muscle.

PubMed

Sirvent, Pascal; Douillard, Aymerick; Galbes, Olivier; Ramonatxo, Christelle; Py, Guillaume; Candau, Robin; Lacampagne, Alain

2014-01-01

Clenbuterol, a β2-agonist, induces skeletal muscle hypertrophy and a shift from slow-oxidative to fast-glycolytic muscle fiber type profile. However, the cellular mechanisms of the effects of chronic clenbuterol administration on skeletal muscle are not completely understood. As the intracellular Ca2+ concentration must be finely regulated in many cellular processes, the aim of this study was to investigate the effects of chronic clenbuterol treatment on force, fatigue, intracellular calcium (Ca2+) homeostasis and Ca2+-dependent proteolysis in fast-twitch skeletal muscles (the extensor digitorum longus, EDL, muscle), as they are more sensitive to clenbuterol-induced hypertrophy. Male Wistar rats were chronically treated with 4 mg.kg-1 clenbuterol or saline vehicle (controls) for 21 days. Confocal microscopy was used to evaluate sarcoplasmic reticulum Ca2+ load, Ca2+-transient amplitude and Ca2+ spark properties. EDL muscles from clenbuterol-treated animals displayed hypertrophy, a shift from slow to fast fiber type profile and increased absolute force, while the relative force remained unchanged and resistance to fatigue decreased compared to control muscles from rats treated with saline vehicle. Compared to control animals, clenbuterol treatment decreased Ca2+-transient amplitude, Ca2+ spark amplitude and frequency and the sarcoplasmic reticulum Ca2+ load was markedly reduced. Conversely, calpain activity was increased by clenbuterol chronic treatment. These results indicate that chronic treatment with clenbuterol impairs Ca2+ homeostasis and this could contribute to the remodeling and functional impairment of fast-twitch skeletal muscle.

Statistical significance of hair analysis of clenbuterol to discriminate therapeutic use from contamination.

PubMed

Krumbholz, Aniko; Anielski, Patricia; Gfrerer, Lena; Graw, Matthias; Geyer, Hans; Schänzer, Wilhelm; Dvorak, Jiri; Thieme, Detlef

2014-01-01

Clenbuterol is a well-established β2-agonist, which is prohibited in sports and strictly regulated for use in the livestock industry. During the last few years clenbuterol-positive results in doping controls and in samples from residents or travellers from a high-risk country were suspected to be related the illegal use of clenbuterol for fattening. A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to detect low clenbuterol residues in hair with a detection limit of 0.02 pg/mg. A sub-therapeutic application study and a field study with volunteers, who have a high risk of contamination, were performed. For the application study, a total dosage of 30 µg clenbuterol was applied to 20 healthy volunteers on 5 subsequent days. One month after the beginning of the application, clenbuterol was detected in the proximal hair segment (0-1 cm) in concentrations between 0.43 and 4.76 pg/mg. For the second part, samples of 66 Mexican soccer players were analyzed. In 89% of these volunteers, clenbuterol was detectable in their hair at concentrations between 0.02 and 1.90 pg/mg. A comparison of both parts showed no statistical difference between sub-therapeutic application and contamination. In contrast, discrimination to a typical abuse of clenbuterol is apparently possible. Due to these findings results of real doping control samples can be evaluated. Copyright © 2014 John Wiley & Sons, Ltd.

Sulfonated polystyrene magnetic nanobeads coupled with immunochromatographic strip for clenbuterol determination in pork muscle.

PubMed

Wu, Kesheng; Guo, Liang; Xu, Wei; Xu, Hengyi; Aguilar, Zoraida P; Xu, Guomao; Lai, Weihua; Xiong, Yonghua; Wan, Yiqun

2014-11-01

A magnetic solid-phase extraction method (MSPE) was developed to pre-concentrate and cleanup clenbuterol (CLE) from pork muscle. Novel sulfonated polystyrene magnetic nanobeads (spMNBs) were synthesized via a one-pot emulsion copolymerization method by using divinylbenzene, styrene, and sodium styrene sulfonate in the presence of oleic acid-modified and 10-undecylenic acid-modified magnetic ferrofluid. The resulting spMNBs exhibited high adsorption efficiency for CLE and for 10 other common beta-adrenergic agonists, namely, brombuterol, ractopamine, tulobuterol, bambuterol, cimbuterol, mabuterol, clorprenaline, penbutolol, salbutamol, and cimaterol. The adsorption behavior of the spMNBs for CLE was described by the Langmuir equation with a maximum adsorption capacity of 0.41 mg/g. Under the optimized parameters, the extraction of CLE from 0.5 g of pork muscle required 25mg of the spMNBs at a shortened adsorption time (0.5 min). The proposed MSPE was coupled with colloidal gold nanoparticle-based immunochromatographic assay (MSPE-AuNPIA) for the quantitative detection of CLE residue in pork muscle. The limit of detection and limit of quantification for the pork muscle were 0.10 and 0.24 ng/g, respectively. The intra-day and inter-day assay recoveries at three CLE spiked concentrations ranged from 92.5% to 98.1%, with relative standard deviations ranging from 3.2% to 13.0%. The results of MSPE-AuNPIA were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The CLE values obtained with MSPE-AuNPIA agreed with those obtained with LC-MS/MS. Copyright © 2014 Elsevier B.V. All rights reserved.

Novel method for the rapid and specific extraction of multiple β2 -agonist residues in food by tailor-made Monolith-MIPs extraction disks and detection by gas chromatography with mass spectrometry.

PubMed

Liu, Haibo; Gan, Ning; Chen, Yinji; Ding, Qingqing; Huang, Jie; Lin, Saichai; Cao, Yuting; Li, Tianhua

2016-09-01

A quick and specific pretreatment method based on a series of extraction clean-up disks, consisting of molecularly imprinted polymer monoliths and C18 adsorbent, was developed for the specific enrichment of salbutamol and clenbuterol residues in food. The molecularly imprinted monolithic polymer disk was synthesized using salbutamol as a template through a one-step synthesis process. It can simultaneously and specifically recognize salbutamol and clenbuterol. The monolithic polymer disk and series of C18 disks were assembled with a syringe to form a set of tailor-made devices for the extraction of target molecules. In a single run, salbutamol and clenbuterol can be specifically extracted, cleaned, and eluted by methanol/acetic acid/H2 O. The target molecules, after a silylation derivatization reaction were detected by gas chromatography-mass spectrometry. The parameters including solvent desorption, sample pH, and the cycles of reloading were investigated and discussed. Under the optimized extraction and clean-up conditions, the limits of detection and quantitation were determined as 0.018-0.022 and 0.042-0.049 ng/g for salbutamol and clenbuterol, respectively. The assay described was convenient, rapid, and specific; thereby potentially efficient in the high-throughput analysis of β2 -agonists residues in real food samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clenbuterol Induces Cell Cycle Arrest in C2C12 Myoblasts by Delaying p27 Degradation through β-arrestin 2 Signaling

PubMed Central

Chen, Min; Liu, Chuncheng; Wang, Meng; Wang, Hong; Zhang, Kuo; Zheng, Yu; Yu, Zhengquan; Li, Xiangdong; Guo, Wei; Li, Ning; Meng, Qingyong

2017-01-01

β2-Adrenoceptor (β2-AR) agonists promote muscle growth. The aim of this study was to elucidate some effects of the selective β2-adrenoceptor agonist clenbuterol (CLB) on myoblast proliferation. We found that CLB induces cell cycle arrest in C2C12 myoblasts. This effect is partly due to the enhanced stability of p27, rather than the increased gene transcription via cAMP response element-binding protein (CREB). Specifically, CLB treatment enhanced the accumulation of p27 in the nucleus while depleting it from the cytosol via a mechanism that requires β2-AR. Surprisingly, p27 accumulation was not reversed by the protein kinase A (PKA) inhibitor H-89, but interestingly, was alleviated by the knockdown of β-arrestin 2. Thus, our work provides a basis for β2-AR agonists inhibit myoblasts proliferation through signaling via β2-AR, β-arrestin 2, and p27. PMID:29104500

Anabolic effects of clenbuterol after long-term treatment and withdrawal in t the rat.

PubMed

Cartañà, J; Segués, T; Yebras, M; Rothwell, N J; Stock, M J

1994-09-01

Injection of rats with the beta 2-adrenoceptor agonist clenbuterol (1 mg/kg/d for 15 days) stimulated an increase in body weight (9%) and protein (8%) and water (7%) content, but reduced food intake (4%) and epididymal fat pad mass (39%). Nine days after termination of treatment, ex-clenbuterol rats were heavier (5%) and had a greater protein (7%) and water (6%) content and lower fat pad mass (32%) than controls. Clenbuterol-fed rats (2 mg/kg diet for 10 days, providing an average of 0.04 mg clenbuterol/kg/d) increased body weight (7%), muscle mass (15% to 21%), and muscle protein content (9% to 26%), whereas epididymal fat pad weight and muscle glycogen content were reduced. During the withdrawal period, the greater body weight of ex-clenbuterol rats was sustained overall (ANOVA, P < .00005), but by day 10 this difference was no longer significant. At this point, gastrocnemius muscle mass was still higher (11%) when compared with that of control animals, but soleus muscle mass, muscle glycogen concentration, and epididymal fat pad weight had reverted to control values. These results were corroborated in a subsequent experiment using older rats. It was concluded that, unlike other beta-adrenoceptor-mediated effects, muscle protein accumulated during clenbuterol treatment can be maintained in certain muscles after removal of the drug for a period of time that is at least equivalent to the duration of treatment. This could have implications for the potential therapeutic use of this class of compound, and differences in the response observed between muscle types may help to elucidate the mechanisms responsible for the muscle protein deposition induced by clenbuterol.

Effects of drugs which influence renal transport systems on the urinary excretion of the beta 2-adrenoceptor agonist clenbuterol and the anabolic steroids ethinylestradiol and methyltestosterone.

PubMed

Gleixner, A; Sauerwein, H; Meyer, H H

1997-01-01

The aim of this study was to determine whether the illegal application of clenbuterol, ethinylestradiol and methyltestosterone in cattle as growth promoters can be concealed by co-treatment with drugs that affect urinary excretion. Six male veal calves were fed with 0.8 micrograms clenbuterol kg-1 of body weight (BW), 3.5 micrograms ethinylestradiol kg-1 BW and 35 micrograms methyltestosterone kg-1 BW together twice daily for 28 days. At the eighth day of clenbuterol, ethinylestradiol and methyltestosterone treatment each calf was additionally fed either with probenecid, para-aminohippuric acid, trimethoprim, famotidine or cimetidine at three different doses which were increased in weekly intervals. During the treatment 24 h-urine and blood samples (once daily) were obtained and analysed for clenbuterol, ethinylestradiol and methyltestosterone by specific enzyme immunoassay. By high performance liquid chromatography/enzyme immunoassay it was determined whether these drugs or their metabolites interfered with the immunological detection of the growth promoters. Clenbuterol, ethinylestradiol and methyltestosterone could be detected in plasma and urine throughout the whole experiment. Co-treatment with probenecid led to a five-fold reduction in urinary excretion of ethinylestradiol and co-treatment with trimethoprim led to a three-fold reduction in urinary excretion of clenbuterol. None of the drugs reduced urinary excretion of the growth promoters to concentrations below the limit of detection. The detection of these three growth promoters in urine samples from calves which were co-treated with the drugs tested in this study can thus not be prevented.

Chronic clenbuterol administration negatively alters cardiac function.

PubMed

Sleeper, Margaret M; Kearns, Charles F; McKeever, Kenneth H

2002-04-01

Chronic administration of pharmacological levels of beta2-agonists have been shown to have toxic effects on the heart; however, no data exist on cardiac function after chronic clenbuterol administration. The purpose of this study was to examine the effect of therapeutic levels of clenbuterol on cardiac performance. Twenty unfit Standardbred mares were divided into four experimental groups: clenbuterol (2.4 microg.kg(-1) twice daily 5 d.wk(-1)) plus exercise (20 min at 50% .VO(2max)) (CLENEX; N = 6), clenbuterol (CLEN; N = 6), exercise (EX; N = 4), and control (CON; N = 4). M-mode and two-dimensional echocardiography (2.5-MHz sector scanner transducer) were used to measure cardiac size and function before and immediately after an incremental exercise test, before and after 8 wk of drug and/or exercise treatments. After treatment, CLENEX and CLEN demonstrated significantly higher left ventricular internal dimension (LVD) at end diastole (+23.7 +/- 4.8%; +25.6 +/- 4.1%), LVD at end systole (+29.2 +/- 8.7%; +40.1 +/- 7.9%), interventricular septal wall thickness (IVS) at end diastole (+28.9 +/- 11.0%; +30.7 +/- 7.0%), IVS at end systole (+29.2 +/- 8.7%; +40.1 +/- 7.9%), and left ventricular posterior wall systolic thickness (+43.1 +/- 14.%; +45.8 +/- 14.1%). CLENEX and CLEN had significantly increased aortic root dimensions (+29.9 +/- 6.1%; +24.0 +/- 1.7%), suggesting increased risk of aortic rupture. Taken together, these data indicate that chronic clenbuterol administration may negatively alter cardiac function.

Metabolomic analysis of swine urine treated with β2-agonists by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

PubMed

Wu, Yuping; Bi, Yanfeng; Bingga, Gali; Li, Xiaowei; Zhang, Suxia; Li, Jiancheng; Li, Hui; Ding, Shuangyang; Xia, Xi

2015-06-26

The illegal use of β2-agonists in livestock production was previously detected by efficient methods based on mass spectrometry to control the residues of these drugs. Nevertheless, such methods still remain a challenging task for authorities who monitor these residues because the use of "cocktails" composed of mixtures of low amounts of several substances as well as the synthesis of new compounds of unknown structure prevent efficient prevention of illegal use of growth-promoting agents. Here, we outlined a metabolomics-based strategy for detecting the use of "cocktails" composed of mixtures of low amounts of three β2-agonists via urine profiling. Urine profiles of controls and swine treated with mixture of low amounts of three substances (clenbuterol, salbutamol, and ractopamine) were analyzed with ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The metabolic differences between controls and β2-agonists-treated groups were compared using multivariate data analysis. Fourteen metabolites were identified related with the β2-agonists treatment, while two co-biomarkers, 2-indolecarboxylic acid and fluorometholone acetate, either in single or "cocktails" of low-dose mixture of clenbuterol, salbutamol, and ractopamine, could be considered as diagnostic markers for the detection of illegal use of β2-agonists. The results of depletion study demonstrated that it is practical to use the markers for monitoring of β2-agonists. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of combined stretching and clenbuterol on disuse atrophy in rat soleus muscle.

PubMed

Yamazaki, Toshiaki; Yokogawa, Masami; Tachino, Katsuhiko

2009-01-01

Clinically, disuse muscle atrophy is often seen among patients who are severely debilited and are on prolonged bed rest. Common physical therapy interventions are not successful in preventing disuse muscle atrophy early in the medical treatment of critically ill patients. In situations such as this, the use of a β 2-adrenergic agonist such as clenbuterol (Cb) may be of benefit in preventing atrophy. Also, recent studies have suggested that stretching is possible in preventing disuse muscle atrophy and the decline in muscle strength. The objective of this study was to evaluate the effects of Cb medication combined with stretching (ST) on rat soleus muscle (SOL) during the progression of disuse muscle atrophy. Thirty-five male Wistar rats were used in this study. The rats were divided into five groups: control (CON), hindlimb-unweighting (HU) only, HU+ST, HU+Cb medication, and HU+ST+Cb groups. The right SOL in stretching groups was maintained a stretched position for one hour daily by passively dorsiflexing the ankle joint under non-anesthesia. The experimental period was 2 weeks. In the ST group, peak twitch tension per cross-sectional area in soleus muscle was significantly larger than in the Cb group, while there was no significant difference between the CON and ST groups. The conversion of type I to type II fibers that was observed in the Cb group was not recognized in the combined ST and Cb group. Distinct effect of combined stretching and Cb medication was not recognized statistically. The results indicate that Cb affects muscle morphological characteristics while stretching affects contractile properties. These data suggest that a combined ST and Cb intervention considered the type-specificity of muscle fiber may be need more consideration for preventing disuse muscle atrophy and the decline in muscle strength.

Cardiac lipin 1 expression is regulated by the peroxisome proliferator activated receptor γ coactivator 1α/estrogen related receptor axis

PubMed Central

Mitra, Mayurranjan S.; Schilling, Joel D.; Wang, Xiaowei; Jay, Patrick Y.; Huss, Janice M.; Su, Xiong; Finck, Brian N.

2011-01-01

Lipin family proteins (lipin 1, 2, and 3) are bifunctional intracellular proteins that regulate metabolism by acting as coregulators of DNA-bound transcription factors and also dephosphorylate phosphatidate to form diacylglycerol [phosphatidate phosphohydrolase activity] in the triglyceride synthesis pathway. Herein, we report that lipin 1 is enriched in heart and that hearts of mice lacking lipin 1 (fld mice) exhibit accumulation of phosphatidate. We also demonstrate that the expression of the gene encoding lipin 1 (Lpin1) is under the control of the estrogen-related receptors (ERRs) and their coactivator the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). PGC-1α, ERRα, or ERRγ overexpression increased Lpin1 transcription in cultured ventricular myocytes and the ERRs were associated with response elements in the first intron of the Lpin1 gene. Concomitant RNAi-mediated knockdown of ERRα and ERRγ abrogated the induction of lipin 1 expression by PGC-1α overexpression. Consistent with these data, 3-fold overexpression of PGC-1α in intact myocardium of transgenic mice increased cardiac lipin 1 and ERRα/γ expression. Similarly, injection of the β2-adrenergic agonist clenbuterol induced PGC-1α and lipin 1 expression, and the induction in lipin 1 after clenbuterol occurred in a PGC-1α-dependent manner. In contrast, expression of PGC-1α, ERRα, ERRγ, and lipin 1 was down-regulated in failing heart. Cardiac phosphatidic acid phosphohydrolase activity was also diminished, while cardiac phosphatidate content was increased, in failing heart. Collectively, these data suggest that lipin 1 is the principal lipin protein in the myocardium and is regulated in response to physiologic and pathologic stimuli that impact cardiac metabolism. PMID:21549711

Development of a metabolomic approach based on liquid chromatography-high resolution mass spectrometry to screen for clenbuterol abuse in calves.

PubMed

Courant, Frédérique; Pinel, Gaud; Bichon, Emmanuelle; Monteau, Fabrice; Antignac, Jean-Philippe; Le Bizec, Bruno

2009-08-01

Beta-agonist compounds can be misused in food-producing animals for growth promoting purposes. Efficient methods based on mass spectrometry detection have been developed to ensure the control of such veterinary drug residues. Nevertheless, the use of "cocktails" composed of mixtures of low amounts of several substances as well as the synthesis of new compounds of unknown structure prevent efficient prevention. To circumvent those problems, new analytical tools able to detect such abuse are today mandatory. In this context, metabolomics may represent a new emerging strategy for investigating the global physiological effects associated to a family of substances and therefore, to suspect the administration of beta-agonists (either "cocktails" or unknown compounds). As a first demonstration of feasibility, an untargeted metabolomic approach based on liquid chromatography coupled to high resolution mass spectrometry measurements was developed and made it possible to highlight metabolic modifications in urine consecutively to a clenbuterol administration. By the means of chemometrics, those metabolic differences were used to build predictive models able to suspect clenbuterol administration in calves. This new approach may be considered of valuable interest to overcome current limitations in the control of growth promoters' abuse, with promising perspectives in terms of screening.

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.

Effect of Serum from Chickens Treated with Clenbuterol on Myosin Accumulation, Beta-Adrenergic Receptor Population, and Cyclic AM Synthesis in Embryonic Chicken Skeletal Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Wuethrich, A. J.; Hancock, D. L.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Broiler chickens at 35 days of age were fed 1 ppm clenbuterol for 14 days. This level of dietary clenbuterol led to 5-7% increases in weights of leg and breast muscle tissue. At the end of the 14-day period, serum was prepared from both control and clenbuterol-treated chickens and was then employed as a component of cell culture media at a final concentration of 20% (v/v). Muscle cell cultures were prepared from both the leg and breast muscle groups of twelve-day chick embryos. Treatment groups included control chicken serum to which 10 nM, 50 nM, and 1 micron clenbuterol had been added, as well as cells grown in media containing 10% horse serum. Cultures were subjected to each treatment for 3 days beginning on the seventh day in culture. Neither the percent fusion nor the number of nuclei in myotubes were significantly affected by any of the treatments. The quantity of MHC was not increased by serum from clenbuterol-treated chickens in either breast and leg muscle cultures; however, MHC quantity was 50- 100% higher in cultures grown in control chicken serum to which 10 nM and 50 nM clenbuterol had also been added. The Beta-AR population was 4,000-7,000 Beta-AR per cell in cultures grown in chicken serum, with leg muscle cultures having approximately 25-30% more receptors than breast muscle cultures. Receptor population was not significantly affected by the presence of clenbuterol or by the presence of serum from clenbuterol-treated chickens. In contrast, the Beta-AR population in leg and breast muscle cultures grown in the presence of 10% horse serum was 18,000-20,000 Beta-AR per cell. Basal concentration of cAMP was not significantly affected by any of the treatments. When cultures grown in chicken serum were stimulated for 10 min with 1 micron isoproterenol, limited increases of 12-20% in cAMP concentration above basal levels were observed. However, when cultures grown in the presence of horse serum were stimulated with 1 micron isoproterenol, increases of 600-800 % in cAMP concentration above basal levels were observed. Thus, not only did cells grown in horse serum have a higher Beta-AR population, each receptor had a higher capacity for cAMP synthesis following isoproterenol stimulation. Finally, the hypothesis was tested that clenbuterol exerts its action on muscle protein content by changes in cAMP concentration. No correlation was apparent between basal cAMP concentration and MHC content.

Flow-injection chemiluminescence method to detect a β2 adrenergic agonist.

PubMed

Zhang, Guangbin; Tang, Yuhai; Shang, Jian; Wang, Zhongcheng; Yu, Hua; Du, Wei; Fu, Qiang

2015-02-01

A new method for the detection of β2 adrenergic agonists was developed based on the chemiluminescence (CL) reaction of β2 adrenergic agonist with potassium ferricyanide-luminol CL. The effect of β2 adrenergic agonists including isoprenaline hydrochloride, salbutamol sulfate, terbutaline sulfate and ractopamine on the CL intensity of potassium ferricyanide-luminol was discovered. Detection of the β2 adrenergic agonist was carried out in a flow system. Using uniform design experimentation, the influence factors of CL were optimized. The optimal experimental conditions were 1 mmol/L of potassium ferricyanide, 10 µmol/L of luminol, 1.2 mmol/L of sodium hydroxide, a flow speed of 2.6 mL/min and a distance of 1.2 cm from 'Y2 ' to the flow cell. The linear ranges and limit of detection were 10-100 and 5 ng/mL for isoprenaline hydrochloride, 20-100 and 5 ng/mL for salbutamol sulfate, 8-200 and 1 ng/mL for terbutaline sulfate, 20-100 and 4 ng/mL for ractopamine, respectively. The proposed method allowed 200 injections/h with excellent repeatability and precision. It was successfully applied to the determination of three β2 adrenergic agonists in commercial pharmaceutical formulations with recoveries in the range of 96.8-98.5%. The possible CL reaction mechanism of potassium ferricyanide-luminol-β2 adrenergic agonist was discussed from the UV/vis spectra. Copyright © 2014 John Wiley & Sons, Ltd.

Development of a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) for the detection of phenylethanolamine A in tissue and feed samples and confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS).

PubMed

Cao, Biyun; He, Guangzhao; Yang, Hong; Chang, Huafang; Li, Shuqun; Deng, Anping

2013-10-15

Phenylethanolamine A (PA) is a new emerged β-adrenergic agonist illegally used as feed additives for growth promotion. In this study, a highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for the detection of PA in tissue and feed samples was developed and confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). By reduction of nitryl group to amino group, the PA derivative was synthesized and coupled to carrier proteins with diazobenzidine method. The antisera obtained from four immunized rabbits were characterized in terms of sensitivity and specificity. All antisera displayed high sensitivity with IC50 values lower than 0.48 ng mL(-1). The most sensitive ELISA was established with IC50 and limit of detection (LOD) values of 0.049 ng mL(-1) and 0.003 ng mL(-1), respectively. The cross-reactivity (CR) values of the antisera with three frequently used β-adrenergic agonists (clenbuterol, salbutamol and ractopamine) were lesser than 0.39%; there was no CR of the antisera with other six compounds including two structurally related substances (isoproterenol, phenylephrine). To investigate the accuracy and precision of the assay, swine kidney, liver, meat and feed samples were fortified with PA at different content and analyzed by ELISA. Acceptable recovery rates of 92.2-113.7% and intra-assay coefficients of variation of 3.8-10.9% (n=3) were achieved. Seven spiked samples were simultaneously analyzed by ELISA and LC-MS/MS. There was a high correlation coefficient of 0.9956 (n=7) between the two methods. The proposed ELISA proven to be a feasible quantitative/screening method for PA analysis in tissue and feed samples with the properties of high sensitivity and specificity, high sample throughput and low expensive. © 2013 Elsevier B.V. All rights reserved.

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.

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

Endogenous PKI gamma limits the duration of the anti-apoptotic effects of PTH and beta-adrenergic agonists in osteoblasts.

PubMed

Chen, Xin; Song, In-Hwan; Dennis, James E; Greenfield, Edward M

2007-05-01

PKI gamma knockdown substantially extended the anti-apoptotic effects of PTH and beta-adrenergic agonists, whereas PKI gamma overexpression decreased these effects. Therefore, inhibition of PKI gamma activity may provide a useful co-therapy in combination with intermittent PTH or beta-adrenergic agonists for bone loss in conditions such as osteoporosis. PTH has both catabolic and anabolic effects on bone, which are primarily caused by cAMP/protein kinase A (PKA) signaling and regulation of gene expression. We previously showed that protein kinase inhibitor-gamma (PKI gamma) is required for efficient termination of cAMP/PKA signaling and gene expression after stimulation with PTH or beta-adrenergic agonists. Inhibition of osteoblast apoptosis is thought to be an important, but transient, mechanism partly responsible for the anabolic effects of intermittent PTH. Therefore, we hypothesized that endogenous PKI gamma also terminates the anti-apoptotic effect of PTH. PKI gamma knockdown by antisense transfection or siRNA was used to examine the ability of endogenous PKI gamma to modulate the anti-apoptotic effects of PTH and beta-adrenergic agonists in ROS 17/2.8 cells. Knockdown of PKI gamma substantially extended the anti-apoptotic effects of PTH, whether apoptosis was induced by etoposide or dexamethasone. In contrast, overexpression of PKI gamma decreased the anti-apoptotic effect of PTH pretreatment. This study is also the first demonstration that beta-adrenergic agonists mimic the anti-apoptotic effects of PTH in osteoblasts. Moreover, PKI gamma knockdown also substantially extended this anti-apoptotic effect of beta-adrenergic agonists. Taken together, these results show that endogenous PKI gamma limits the duration of the anti-apoptotic effects of cAMP/PKA signaling in osteoblasts. Because significant individual variability exists in the anabolic responses to PTH therapy in current clinical treatment of osteoporosis, inhibition of PKI gamma activity may provide a useful co-therapy in combination with intermittent PTH or beta-adrenergic agonists for bone loss in conditions such as osteoporosis. However, the potential use of such a co-therapy would depend on it not adversely affecting bone formation or other organ systems.

Alpha-2 adrenergic agonists for the prevention of cardiac complications among adults undergoing surgery.

PubMed

Duncan, Dallas; Sankar, Ashwin; Beattie, W Scott; Wijeysundera, Duminda N

2018-03-06

The surgical stress response plays an important role on the pathogenesis of perioperative cardiac complications. Alpha-2 adrenergic agonists attenuate this response and may help prevent postoperative cardiac complications. To determine the efficacy and safety of α-2 adrenergic agonists for reducing mortality and cardiac complications in adults undergoing cardiac surgery and non-cardiac surgery. We searched CENTRAL (2017, Issue 4), MEDLINE (1950 to April Week 4, 2017), Embase (1980 to May 2017), the Science Citation Index, clinical trial registries, and reference lists of included articles. We included randomized controlled trials that compared α-2 adrenergic agonists (i.e. clonidine, dexmedetomidine or mivazerol) against placebo or non-α-2 adrenergic agonists. Included trials had to evaluate the efficacy and safety of α-2 adrenergic agonists for preventing perioperative mortality or cardiac complications (or both), or measure one or more relevant outcomes (i.e. death, myocardial infarction, heart failure, acute stroke, supraventricular tachyarrhythmia and myocardial ischaemia). Two authors independently assessed trial quality, extracted data and independently performed computer entry of abstracted data. We contacted study authors for additional information. Adverse event data were gathered from the trials. We evaluated included studies using the Cochrane 'Risk of bias' tool, and the quality of the evidence underlying pooled treatment effects using GRADE methodology. Given the clinical heterogeneity between cardiac and non-cardiac surgery, we analysed these subgroups separately. We expressed treatment effects as pooled risk ratios (RR) with 95% confidence intervals (CI). We included 47 trials with 17,039 participants. Of these studies, 24 trials only included participants undergoing cardiac surgery, 23 only included participants undergoing non-cardiac surgery and eight only included participants undergoing vascular surgery. The α-2 adrenergic agonist studied was clonidine in 21 trials, dexmedetomidine in 24 trials and mivazerol in two trials.In non-cardiac surgery, there was high quality evidence that α-2 adrenergic agonists led to a similar risk of all-cause mortality compared with control groups (1.3% with α-2 adrenergic agonists versus 1.7% with control; RR 0.80, 95% CI 0.61 to 1.04; participants = 14,081; studies = 16). Additionally, the risk of cardiac mortality was similar between treatment groups (0.8% with α-2 adrenergic agonists versus 1.0% with control; RR 0.86, 95% CI 0.60 to 1.23; participants = 12,525; studies = 5, high quality evidence). The risk of myocardial infarction was probably similar between treatment groups (RR 0.94, 95% CI 0.69 to 1.27; participants = 13,907; studies = 12, moderate quality evidence). There was no associated effect on the risk of stroke (RR 0.93, 95% CI 0.55 to 1.56; participants = 11,542; studies = 7; high quality evidence). Conversely, α-2 adrenergic agonists probably increase the risks of clinically significant bradycardia (RR 1.59, 95% CI 1.18 to 2.13; participants = 14,035; studies = 16) and hypotension (RR 1.24, 95% CI 1.03 to 1.48; participants = 13,738; studies = 15), based on moderate quality evidence.There was insufficient evidence to determine the effect of α-2 adrenergic agonists on all-cause mortality in cardiac surgery (RR 0.52, 95% CI 0.26 to 1.04; participants = 1947; studies = 16) and myocardial infarction (RR 1.01, 95% CI 0.43 to 2.40; participants = 782; studies = 8), based on moderate quality evidence. There was one cardiac death in the clonidine arm of a study of 22 participants. Based on very limited data, α-2 adrenergic agonists may have reduced the risk of stroke (RR 0.37, 95% CI 0.15 to 0.93; participants = 1175; studies = 7; outcome events = 18; low quality evidence). Conversely, α-2 adrenergic agonists increased the risk of bradycardia from 6.4% to 12.0% (RR 1.88, 95% CI 1.35 to 2.62; participants = 1477; studies = 10; moderate quality evidence), but their effect on hypotension was uncertain (RR 1.19, 95% CI 0.87 to 1.64; participants = 1413; studies = 9; low quality evidence).These results were qualitatively unchanged in subgroup analyses and sensitivity analyses. Our review concludes that prophylactic α-2 adrenergic agonists generally do not prevent perioperative death or major cardiac complications. For non-cardiac surgery, there is moderate-to-high quality evidence that these agents do not prevent death, myocardial infarction or stroke. Conversely, there is moderate quality evidence that these agents have important adverse effects, namely increased risks of hypotension and bradycardia. For cardiac surgery, there is moderate quality evidence that α-2 adrenergic agonists have no effect on the risk of mortality or myocardial infarction, and that they increase the risk of bradycardia. The quality of evidence was inadequate to draw conclusions regarding the effects of alpha-2 agonists on stroke or hypotension during cardiac surgery.

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.

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.

Use of ß-adrenergic agonists in hybrid catfish

USDA-ARS?s Scientific Manuscript database

Ractopamine hydrochloride (RH) is a potent ß-adrenergic agonist that has been used in some species of fish to improve growth performance and dress out characteristics. While this metabolic modifier has been shown to have positive effects on growth of fish, little research has focused on the mechani...

Development of an immunochromatographic assay for the detection of the feed additive zilpaterol

USDA-ARS?s Scientific Manuscript database

Zilpaterol is a beta-adrenergic agonist feed additive approved in the United States to increase weight gain and improve feed efficiency of cattle. Countries which ban beta-adrenergic agonist feed additives can reject imported beef products that contain zilpaterol. Therefore, efficient, portable, a...

Evaluation of partial beta-adrenoceptor agonist activity.

PubMed

Lipworth, B J; Grove, A

1997-01-01

A partial beta-adrenoceptor (beta-AR) agonist will exhibit opposite agonist and antagonist activity depending on the prevailing degree of adrenergic tone or the presence of a beta-AR agonist with higher intrinsic activity. In vivo partial beta-AR agonist activity will be evident at rest with low endogenous adrenergic tone, as for example with chronotropicity (beta 1/beta 2), inotropicity (beta 1) or peripheral vasodilatation and finger tremor (beta 2). beta-AR blocking drugs which have partial agonist activity may exhibit a better therapeutic profile when used for hypertension because of maintained cardiac output without increased systemic vascular resistance, along with an improved lipid profile. In the presence of raised endogenous adrenergic tone such as exercise or an exogenous full agonist, beta-AR subtype antagonist activity will become evident in terms of effects on exercise induced heart rate (beta 1) and potassium (beta 2) responses. Reduction of exercise heart rate will occur to a lesser degree in the case of a beta-adrenoceptor blocker with partial beta 1-AR agonist activity compared with a beta-adrenoceptor blocker devoid of partial agonist activity. This may result in reduced therapeutic efficacy in the treatment of angina on effort when using beta-AR blocking drugs with partial beta 1-AR agonist activity. Effects on exercise hyperkalaemia are determined by the balance between beta 2-AR partial agonist activity and endogenous adrenergic activity. For predominantly beta 2-AR agonist such as salmeterol and salbutamol, potentiation of exercise hyperkalaemia occurs. For predominantly beta 2-AR antagonists such as carteolol, either potentiation or attenuation of exercise hyperkalaemia occurs at low and high doses respectively. beta 2-AR partial agonist activity may also be expressed as antagonism in the presence of an exogenous full agonist, as for example attenuation of fenoterol induced responses by salmeterol. Studies are required to investigate whether this phenomenon is relevant in the setting of acute severe asthma.

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.

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.

Agonist-Directed Desensitization of the β2-Adrenergic Receptor

PubMed Central

Goral, Vasiliy; Jin, Yan; Sun, Haiyan; Ferrie, Ann M.; Wu, Qi; Fang, Ye

2011-01-01

The β2-adrenergic receptor (β2AR) agonists with reduced tachyphylaxis may offer new therapeutic agents with improved tolerance profile. However, receptor desensitization assays are often inferred at the single signaling molecule level, thus ligand-directed desensitization is poorly understood. Here we report a label-free biosensor whole cell assay with microfluidics to determine ligand-directed desensitization of the β2AR. Together with mechanistic deconvolution using small molecule inhibitors, the receptor desensitization and resensitization patterns under the short-term agonist exposure manifested the long-acting agonism of salmeterol, and differentiated the mechanisms of agonist-directed desensitization between a full agonist epinephrine and a partial agonist pindolol. This study reveals the cellular mechanisms of agonist-selective β2AR desensitization at the whole cell level. PMID:21541288

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.

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

Contractile response of bovine lateral saphenous vein to ergovaline serotonin2A a2A- and a2C-adrenergic receptor agonists relative to time off endophyte-infected tall fescue

USDA-ARS?s Scientific Manuscript database

Previous research has demonstrated differences in contractile responses to ergot alkaloids, serotonin (5HT), and adrenergic agonists by lateral saphenous veins collected from cattle that grazed either endophyte (Neotyphodium coenophialum)-infected or endophyte-free tall fescue (Lolium arundinaceum),...

Determination of Zilpaterol in Horse Urine from Withdrawal Day 0 to Day 21 by UPLC-MS/MS and ELISA

USDA-ARS?s Scientific Manuscript database

Zilpaterol is a beta-adrenergic agonist that is approved in the United States, Mexico and South Africa as a feed additive to increase weight gain and improve feed efficiency of cattle. Beta-adrenergic agonists have a long history of illicit and off-label use in livestock, competitive sport animals,...

Memory Enhancement Induced by Post-Training Intrabasolateral Amygdala Infusions of [beta]-Adrenergic or Muscarinic Agonists Requires Activation of Dopamine Receptors: Involvement of Right, but Not Left, Basolateral Amygdala

ERIC Educational Resources Information Center

LaLumiere, Ryan T.; McGaugh, James L.

2005-01-01

Previous findings indicate that the noradrenergic, dopaminergic, and cholinergic innervations of the basolateral amygdala (BLA) modulate memory consolidation. The current study investigated whether memory enhancement induced by post-training intra-BLA infusions of a [beta]-adrenergic or muscarinic cholinergic agonist requires concurrent activation…

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.

Beta-agonist residues in cattle, chicken and swine livers at the wet market and the environmental impacts of wastewater from livestock farms in Selangor State, Malaysia.

PubMed

Sakai, Nobumitsu; Sakai, Mika; Mohamad Haron, Didi Erwandi; Yoneda, Minoru; Ali Mohd, Mustafa

2016-12-01

Fourteen beta-agonists were quantitatively analyzed in cattle, chicken and swine liver specimens purchased at 14 wet markets in Selangor State, Malaysia, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The health risks of ractopamine and clenbuterol residues in the Malaysian population were assessed based on quantitative data and meat consumption statistics in Malaysia. Wastewater samples collected at swine farms (n = 2) and cattle/cow farms (n = 2) in the Kuala Langat district were analyzed for the presence for the 14 compounds. Wastewater in chicken farms was not collected because there was negligible discharge during the breeding period. The environmental impacts caused by beta-agonists discharged from livestock farms were spatially assessed in the Langat River basin using a geographic information system (GIS). As a result, 10 compounds were detected in the liver specimens. Ractopamine, which is a permitted compound for swine in Malaysia, was frequently detected in swine livers; also, 9 other compounds that are prohibited compounds could be illegally abused among livestock farms. The health risks of ractopamine and clenbuterol were assessed to be minimal as their hazard quotients were no more than 7.82 × 10 -4 and 2.71 × 10 -3 , respectively. Five beta-agonists were detected in the wastewater samples, and ractopamine in the swine farm resulted in the highest contamination (30.1 μg/L). The environmental impacts of the beta-agonists in the Langat River basin were generally concluded to be minimal, but the ractopamine contamination released from swine farms was localized in coastal areas near the estuary of the Langat River basin because most swine farms were located in that region. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Beta-Adrenergic Receptor Expression in Muscle Cells

NASA Technical Reports Server (NTRS)

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

1999-01-01

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

Effect of clenbuterol on tracheal mucociliary transport in horses undergoing simulated long-distance transportation.

PubMed

Norton, J L; Jackson, K; Chen, J W; Boston, R; Nolen-Walston, R D

2013-01-01

Pneumonia is observed in horses after long-distance transportation in association with confinement of head position leading to reduction in tracheal mucociliary clearance rate (TMCR). Clenbuterol, a beta-2 agonist shown to increase TMCR in the horse, will ameliorate the effects of a fixed elevated head position on large airway contamination and inflammation in a model of long-distance transportation model. Six adult horses. A cross-over designed prospective study. Horses were maintained with a fixed elevated head position for 48 hours to simulate long-distance transport, and treated with clenbuterol (0.8 μg/kg PO q12h) or a placebo starting 12 hours before simulated transportation. TMCR was measured using a charcoal clearance technique. Data were collected at baseline and 48 hours, and included TMCR, tracheal wash cytology and quantitative culture, rectal temperature, CBC, fibrinogen, and serum TNFα, IL-10, and IL-2 levels. There was a 18-21 day washout between study arms, and data were analyzed using regression analysis and Wilcoxon rank-sum tests. Tracheal mucociliary clearance rate was significantly decreased after transportation in both treatment (P = .002) and placebo (P = .03) groups. There was a significant effect of treatment on TMCR, with the treatment group showing half the reduction in TMCR compared with the placebo group (P = .002). Other significant differences between before- and after-transportation samples occurred for serum fibrinogen, peripheral eosinophil count, quantitative culture, tracheal bacteria, and degenerate neutrophils, though no treatment effect was found. Treatment with clenbuterol modestly attenuates the deleterious effects of this long-distance transportation model on tracheal mucociliary clearance. Copyright © 2013 by the American College of Veterinary Internal Medicine.

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.

Regulation of the mRNA-binding protein AUF1 by activation of the beta-adrenergic receptor signal transduction pathway.

PubMed

Pende, A; Tremmel, K D; DeMaria, C T; Blaxall, B C; Minobe, W A; Sherman, J A; Bisognano, J D; Bristow, M R; Brewer, G; Port, J

1996-04-05

In both cell culture based model systems and in the failing human heart, beta-adrenergic receptors ( beta-AR) undergo agonist-mediated down-regulation. This decrease correlates closely with down-regulation of its mRNA, an effect regulated in part by changes in mRNA stability. Regulation of mRNA stability has been associated with mRNA-binding proteins that recognize A + U-rich elements within the 3'-untranslated regions of many mRNAs encoding proto-oncogene and cytokine mRNAs. We demonstrate here that the mRNA-binding protein, AUF1, is present in both human heart and in hamster DDT1-MF2 smooth muscle cells and that its abundance is regulated by beta-AR agonist stimulation. In human heart, AUF1 mRNA and protein was significantly increased in individuals with myocardial failure, a condition associated with increases in the beta-adrenergic receptor agonist norepinephrine. In the same hearts, there was a significant decrease (approximately 50%) in the abundance of beta1-AR mRNA and protein. In DDT1-MF2 cells, where agonist-mediated destabilization of beta2-AR mRNA was first described, exposure to beta-AR agonist resulted in a significant increase in AUF1 mRNA and protein (approximately 100%). Conversely, agonist exposure significantly decreased (approximately 40%) beta2-adrenergic receptor mRNA abundance. Last, we demonstrate that AUF1 can be immunoprecipitated from polysome-derived proteins following UV cross-linking to the 3'-untranslated region of the human beta1-AR mRNA and that purified, recombinant p37AUF1 protein also binds to beta1-AR 3'-untranslated region mRNA.

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.

REGULATION OF POSTNATAL B-ADRENERGIC RECEPTOR/ADENYLATE CYCLASE DEVELOPMENT BY PRENATAL AGONIST STIMULATION AND STEROIDS: ALTERATIONS IN RAT KIDNEY AND LUNG AFTER EXPOSURE TO TERBUTALINE OR DEXAMETHASONE

EPA Science Inventory

Glucocorticoids and adrenergic stimulation are both thought to control the development of adrenergic receptors/responses. n the current study, rats were exposed to dexamethasone or terbutaline during late gestation and the development of B-binding capabilities and adenylate cycla...

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.

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.

Enantiomeric separation of seven β-agonists by NACE-Study of chiral selectivity with diacetone-d-mannitol-boric acid complex.

PubMed

Lv, Lili; Wang, Lijuan; Li, Jun; Jiao, Yajun; Gao, Shengnan; Wang, Jiachang; Yan, Hongyuan

2017-10-25

A rapid and effective nonaqueous capillary electrophoresis (NACE)-ultraviolet (UV) method was developed for the enantiomeric separation of seven β-agonists. Diacetone-d-mannitol-boric acid complex was used as a new chiral selector. It was in situ synthesized by the reaction of diacetone-d-mannitol and boric acid in methanol medium containing triethylamine. The effects of diacetone-d-mannitol, boric acid, and triethylamine concentrations on the enantioseparation were carefully investigated. Under the optimized conditions, baseline enantioseparation could be obtained for six of the tested β-agonists within 12min. These results were better than that obtained with d-mannitol-boric acid complex in previous work. 11 B nuclear magnetic resonance ( 11 B NMR) was applied to determine the fraction of boron species and confirm the formation of diacetone-d-mannitol-boric acid complex. Validation of the established NACE method was also carried out according to ICH guidelines. Calibration curves showed good linearity with correlation coefficients (r)≥0.9992 over a certain concentration range for each enantiomer of the tested five β-agonists. The relative standard deviations (RSDs) of intra-day precisions and inter-day precisions of migration times were ≤1.4% (n=6), and ≤6.3% (n=10), respectively. That of peak areas were ≤3.7% (n=6), and ≤5.6% (n=10), respectively. The limits of detection (LODs) and the limits of quantitation (LOQs) based on the signal-to-noise ratios of 3 and 10 were found below 1.25μgmL -1 and 5.00μgmL -1 , respectively. The proposed method was successfully applied to the determination of clenbuterol enantiomers in a multi-component pharmaceutical dosage form called "Ambroxol Hydrochloride and Clenbuterol Hydrochloride Oral Solution". Copyright © 2017 Elsevier B.V. All rights reserved.

Conformation guides molecular efficacy in docking screens of activated β-2 adrenergic G protein coupled receptor.

PubMed

Weiss, Dahlia R; Ahn, SeungKirl; Sassano, Maria F; Kleist, Andrew; Zhu, Xiao; Strachan, Ryan; Roth, Bryan L; Lefkowitz, Robert J; Shoichet, Brian K

2013-05-17

A prospective, large library virtual screen against an activated β2-adrenergic receptor (β2AR) structure returned potent agonists to the exclusion of inverse-agonists, providing the first complement to the previous virtual screening campaigns against inverse-agonist-bound G protein coupled receptor (GPCR) structures, which predicted only inverse-agonists. In addition, two hits recapitulated the signaling profile of the co-crystal ligand with respect to the G protein and arrestin mediated signaling. This functional fidelity has important implications in drug design, as the ability to predict ligands with predefined signaling properties is highly desirable. However, the agonist-bound state provides an uncertain template for modeling the activated conformation of other GPCRs, as a dopamine D2 receptor (DRD2) activated model templated on the activated β2AR structure returned few hits of only marginal potency.

Discovery of novel acetanilide derivatives as potent and selective beta3-adrenergic receptor agonists.

PubMed

Maruyama, Tatsuya; Onda, Kenichi; Hayakawa, Masahiko; Matsui, Tetsuo; Takasu, Toshiyuki; Ohta, Mitsuaki

2009-06-01

In the search for potent and selective human beta3-adrenergic receptor (AR) agonists as potential drugs for the treatment of obesity and noninsulin-dependent (type II) diabetes, a novel series of acetanilide-based analogues were prepared and their biological activities were evaluated at the human beta3-, beta2-, and beta1-ARs. Among these compounds, 2-pyridylacetanilide (2f), pyrimidin-2-ylacetanilide (2u), and pyrazin-2-ylacetanilide (2v) derivatives exhibited potent agonistic activity at the beta3-AR with functional selectivity over the beta1- and beta2-ARs. In particular, compound 2u was found to be the most potent and selective beta3-AR agonist with an EC(50) value of 0.11 microM and no agonistic activity for either the beta1- or beta2-AR. In addition, 2f, 2u, and 2v showed significant hypoglycemic activity in a rodent diabetic model.

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

Impaired modulation of postjunctional α1 - but not α2 -adrenergic vasoconstriction in contracting forearm muscle of postmenopausal women.

PubMed

Kruse, Nicholas T; Hughes, William E; Ueda, Kenichi; Hanada, Satoshi; Feider, Andrew J; Iwamoto, Erika; Bock, Joshua M; Casey, Darren P

2018-04-30

Contraction-mediated blunting of postjunctional α-adrenergic vasoconstriction (functional sympatholysis) is attenuated in skeletal muscle of ageing males, brought on by altered postjunctional α 1 - and α 2 -adrenergic receptor sensitivity. The extent to which postjunctional α-adrenergic vasoconstriction occurs in the forearms at rest and during exercise in postmenopausal women remains unknown. The novel findings indicate that contraction-mediated blunting of α 1 - (via intra-arterial infusion of phenylephrine) but not α 2 -adrenergic (via intra-arterial infusion of dexmedetomidine) vasoconstriction was attenuated in postmenopausal women compared to young women. Additional important findings revealed that postjunctional α-adrenergic vasoconstrictor responsiveness at rest does not appear to be affected by age in women. Collectively, these results contribute to our understanding of local neurovascular control at rest and during exercise with age in women. Contraction-mediated blunting of postjunctional α-adrenergic vasoconstriction (functional sympatholysis) is attenuated in older males; however, direct confirmation of this effect remains unknown in postmenopausal women (PMW). The present study examined whether PMW exhibit augmented postjunctional α-adrenergic receptor vasoconstriction at rest and during forearm exercise compared to young women (YW). Eight YW (24 ± 1 years) and eight PMW (65 ± 1 years) completed a series of randomized experimental trials: (1) at rest, (2) under high flow (adenosine infusion) conditions and (3) during 6 min of forearm exercise at relative (20% of maximum) and absolute (7 kg) intensities. Phenylephrine (α 1 -agonist) or dexmedetomidine (α 2 -agonist) was administered during the last 3 min of each trial to elicit α-adrenergic vasoconstriction. Forearm vascular conductance (FVC) was calculated from blood flow and blood pressure. Vasoconstrictor responsiveness was identified as the change in FVC (%) during α-adrenergic agonist infusions from baseline (resting trial) or from steady-state conditions (high flow and exercise trials). During resting and high flow trials, the %FVC during α 1 - and α 2 -agonist stimulation was similar between YW and PMW. During exercise, α 1 -mediated vasoconstriction was blunted in YW vs. PMW at relative (-6 ± 2% vs. -15 ± 3%) and absolute (-4 ± 2% vs. -14 ± 5%) workloads, such that blood flow and FVC were lower in PMW (P < 0.05 for all). Conversely, α 2 -mediated vasoconstriction was similar between YW and PMW at relative (-22 ± 3% vs. -22 ± 4%; P > 0.05) and absolute (-19 ± 3% vs. -18 ± 4%; P > 0.05) workloads. Collectively, these findings demonstrate that despite similar α-adrenergic vasoconstrictor responsiveness at rest, PMW have a decreased ability to attenuate α 1 -adrenergic vasoconstriction in contracting skeletal muscle. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

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.

Nitrosative stress uncovers potent β2-adrenergic receptor-linked vasodilation further enhanced by blockade of clathrin endosome formation.

PubMed

Frame, Mary D; Dewar, Anthony M; Calizo, Rhodora C; Qifti, Androniqi; Scarlata, Suzanne F

2018-06-01

This study investigated the effect of sodium nitroprusside (SNP) preexposure on vasodilation via the β-adrenergic receptor (BAR) system. SNP was used as a nitrosative/oxidative proinflammatory insult. Small arterioles were visualized by intravital microscopy in the hamster cheek pouch tissue (isoflurane, n = 45). Control dilation to isoproterenol (EC 50 : 10 -7 mol/l) became biphasic as a function of concentration after 2 min of exposure to SNP (10 -4 M), with increased potency at picomolar dilation uncovered and decreased efficacy at the micromolar dilation. Control dilation to curcumin was likewise altered after SNP, but only the increased potency at a low dose was uncovered, whereas micromolar dilation was eliminated. The picomolar dilations were blocked by the potent BAR-2 inverse agonist carazolol (10 -9 mol/l). Dynamin inhibition with dynasore mimicked this effect, suggesting that SNP preexposure prevented BAR agonist internalization. Using HeLa cells transfected with BAR-2 tagged with monomeric red fluorescent protein, exposure to 10 -8 -10 -6 mol/l curcumin resulted in internalization and colocalization of BAR-2 and curcumin (FRET) that was prevented by oxidative stress (10 -3 mol/l CoCl 2 ), supporting that stress prevented internalization of the BAR agonist with the micromolar agonist. This study presents novel data supporting that distinct pools of BARs are differentially available after inflammatory insult. NEW & NOTEWORTHY Preexposure to an oxidative/nitrosative proinflammatory insult provides a "protective preconditioning" against future oxidative damage. We examined immediate vasoactive and molecular consequences of a brief preexposure via β-adrenergic receptor signaling in small arterioles. Blocked receptor internalization with elevated reactive oxygen levels coincides with a significant and unexpected vasodilation to β-adrenergic agonists at picomolar doses.

Prevention of neutrophil extravasation by α2-adrenoceptor-mediated endothelial stabilization.

PubMed

Herrera-García, Ada María; Domínguez-Luis, María Jesús; Arce-Franco, María; Armas-González, Estefanía; Álvarez de La Rosa, Diego; Machado, José David; Pec, Martina K; Feria, Manuel; Barreiro, Olga; Sánchez-Madrid, Francisco; Díaz-González, Federico

2014-09-15

Adrenergic receptors are expressed on the surface of inflammation-mediating cells, but their potential role in the regulation of the inflammatory response is still poorly understood. The objectives of this work were to study the effects of α2-adrenergic agonists on the inflammatory response in vivo and to determine their mechanism of action. In two mouse models of inflammation, zymosan air pouch and thioglycolate-induced peritonitis models, the i.m. treatment with xylazine or UK14304, two α2-adrenergic agonists, reduced neutrophil migration by 60%. The α2-adrenergic antagonist RX821002 abrogated this effect. In flow cytometry experiments, the basal surface expression of L-selectin and CD11b was modified neither in murine nor in human neutrophils upon α2-agonist treatment. Similar experiments in HUVEC showed that UK14304 prevented the activation-dependent upregulation of ICAM-1. In contrast, UK14304 augmented electrical resistance and reduced macromolecular transport through a confluent HUVEC monolayer. In flow chamber experiments, under postcapillary venule-like flow conditions, the pretreatment of HUVECs, but not neutrophils, with α2-agonists decreased transendothelial migration, without affecting neutrophil rolling. Interestingly, α2-agonists prevented the TNF-α-mediated decrease in expression of the adherens junctional molecules, VE-cadherin, β-catenin, and plakoglobin, and reduced the ICAM-1-mediated phosphorylation of VE-cadherin by immunofluorescence and confocal analysis and Western blot analysis, respectively. These findings indicate that α2-adrenoceptors trigger signals that protect the integrity of endothelial adherens junctions during the inflammatory response, thus pointing at the vascular endothelium as a therapeutic target for the management of inflammatory processes in humans. Copyright © 2014 by The American Association of Immunologists, Inc.

Interleukin 13 and the beta-adrenergic blockade theory of asthma revisited 40 years later.

PubMed

Townley, Robert G

2007-09-01

Beta2-Adrenergic agonists are the most potent agents clinically used in inhibiting and preventing the immediate response to bronchoconstricting agents and in inhibiting mast cell mediator release. This raises the possibility that an abnormality in beta-adrenergic receptor function or circulating catecholamine levels could contribute to airway hyperresponsiveness. To link interleukin 13 (IL-13) to the pathogenesis of asthma. Almost 4 decades ago, Andor Szentivanyi published a beta-adrenergic theory of atopic abnormality in bronchial asthma. He proposed 9 characteristics to define bronchial asthma. Because he published these 9 tenets of the beta-adrenergic blockade theory of asthma in 1968, it is appropriate and important to evaluate their relevance in light of advances in pharmacology, inflammation, and immunology. We describe the effects of the allergic reaction on beta-adrenergic responses and airway responsiveness. Both IL-1beta and tumor necrosis factor a have been detected in increased amounts in bronchial lavage fluids in allergic airway inflammation. Both IL-13 and the proinflammatory cytokines IL-1beta and tumor necrosis factor a have been demonstrated in airway smooth muscle to cause a decreased relaxation response to beta-adrenergic agonist. However, IL-13 has been shown to be necessary and sufficient to produce the characteristics of asthma. The decreased adrenergic bronchodilator activity and associated hypersensitivity to mediators put forth by Szentivanyi can be elicited with IL-13 and support its role in the pathogenesis of asthma.

Adrenergic-agonist-induced Ca2+ fluxes in rat parotid cells are not Na+-dependent.

PubMed Central

Helman, J; Roth, G S; Baum, B J

1985-01-01

We investigated the hypothesis that extracellular Na+ is required for the rapid mobilization of Ca2+ by rat parotid cells after adrenergic stimulation. When Na+ salts in the media were osmotically replaced with either choline chloride (+atropine) or sucrose, efflux of 45Ca2+ from preloaded cells, caused by 10 microM-(-)-adrenaline, was unchanged. Similarly adrenaline stimulated 45Ca2+ uptake into cells under nonsteady-state conditions in the presence or absence of Na+. Monensin, a Na+ ionophore, was able to elicit a modest increase in 45Ca2+ efflux, compared with controls. Studies of net 45Ca2+ flux, performed under near-steady-state conditions, showed that adrenaline caused net 45Ca2+ accumulation, whereas monensin caused net 45Ca2+ release. The effect of monensin required the presence of Na+ in the incubation medium. Both 1 mM-LaCl3 and 0.1 mM-D-600 prevented adrenaline-stimulated 45Ca2+ uptake into cells, but had no effect on monensin-induced changes. We conclude that (1) the rapid mobilization of Ca2+ by adrenergic agonists seen in rat parotid cells does not require a Na+out greater than Na+in gradient and (2) the nature of the monensin effect is quite different from the adrenergic-agonist-induced response. PMID:2413840

Respective contributions of α-adrenergic and non-adrenergic mechanisms in the hypotensive effect of imidazoline-like drugs

PubMed Central

Bruban, Véronique; Feldman, Josiane; Greney, Hugues; Dontenwill, Monique; Schann, Stephan; Jarry, Christian; Payard, Marc; Boutin, Jean; Scalbert, Elizabeth; Pfeiffer, Bruno; Renard, Pierre; Vanhoutte, Paul; Bousquet, Pascal

2001-01-01

The hypotensive effect of imidazoline-like drugs, such as clonidine, was first attributed to the exclusive stimulation of central α2-adrenoceptors (α2ARs). However, a body of evidence suggests that non-adrenergic mechanisms may also account for this hypotension. This work aims (i) to check whether imidazoline-like drugs with no α2-adrenergic agonist activity may alter blood pressure (BP) and (ii) to seek a possible interaction between such a drug and an α2ARs agonist α-methylnoradrenaline (α-MNA). We selected S23515 and S23757, two imidazoline-like drugs with negligible affinities and activities at α2ARs but with high affinities for non-adrenergic imidazoline binding sites (IBS). S23515 decreased BP dose-dependently (−27±5% maximal effect) when administered intracisternally (i.c.) to anaesthetized rabbits. The hypotension induced by S23515 (100 μg kg−1 i.c.) was prevented by S23757 (1 mg kg−1 i.c.) and efaroxan (10 μg kg−1 i.c.), while these compounds, devoid of haemodynamic action by themselves, did not alter the hypotensive effect of α-MNA (3 and 30 μg kg−1 i.c.). Moreover, the α2ARs antagonist rauwolscine (3 μg kg−1 i.c.) did not prevent the effect of S23515. Finally, whilst 3 μg kg−1 of S23515 or 0.5 μg kg−1 of α-MNA had weak hypotensive effects, the sequential i.c. administration of these two drugs induced a marked hypotension (−23±2%). These results indicate that an imidazoline-like drug with no α2-adrenergic properties lowers BP and interacts synergistically with an α2ARs agonist. PMID:11350862

Formoterol, a long-acting β2 adrenergic agonist, improves cognitive function and promotes dendritic complexity in a mouse model of Down syndrome.

PubMed

Dang, Van; Medina, Brian; Das, Devsmita; Moghadam, Sarah; Martin, Kara J; Lin, Bill; Naik, Priyanka; Patel, Devan; Nosheny, Rachel; Wesson Ashford, John; Salehi, Ahmad

2014-02-01

Down syndrome is associated with significant failure in cognitive function. Our previous investigation revealed age-dependent degeneration of locus coeruleus, a major player in contextual learning, in the Ts65Dn mouse model of Down syndrome. We studied whether drugs already available for use in humans can be used to improve cognitive function in these mice. We studied the status of β adrenergic signaling in the dentate gyrus of the Ts65Dn mouse model of Down syndrome. Furthermore, we used fear conditioning to study learning and memory in these mice. Postmortem analyses included the analysis of synaptic density, dendritic arborization, and neurogenesis. We found significant atrophy of dentate gyrus and failure of β adrenergic signaling in the hippocampus of Ts65Dn mice. Our behavioral analyses revealed that formoterol, a long-acting β2 adrenergic receptor agonist, caused significant improvement in the cognitive function in Ts65Dn mice. Postmortem analyses revealed that the use of formoterol was associated with a significant improvement in the synaptic density and increased complexity of newly born dentate granule neurons in the hippocampus of Ts65Dn mice. Our data suggest that targeting β2 adrenergic receptors is an effective strategy for restoring synaptic plasticity and cognitive function in these mice. Considering its widespread use in humans and positive effects on cognition in Ts65Dn mice, formoterol or similar β2 adrenergic receptor agonists with ability to cross the blood brain barrier might be attractive candidates for clinical trials to improve cognitive function in individuals with Down syndrome. Published by Elsevier Inc.

Rapid and sensitive detection of clenbuterol using a fluorescence nanosensor based on diazo coupling mechanism

NASA Astrophysics Data System (ADS)

Thanh Hop Tran, Thi; Huong Do, Thi Mai; Hoang, Mai Ha; Tuyen Nguyen, Duc; Le, Quang Tuan; Nghia Nguyen, Duc; Ngo, Trinh Tung

2015-01-01

In this paper, the fluorescence resonance energy transfer (FRET) effect has been used for fabrication of nanosensor for the detection of clenbuterol. In the nanosensor, the CdTe quantum dots (QDs) are the donors while the acceptor is the super-macromolecule formed by the diazoation coupling mechanism between diazo clenbuterol and naphthylethylene diamine. Changes in fluorescence intensities of nanosensor were used to determine the clenbuterol concentration. We have successfully fabricated a nanosensor for detection of clenbuterol sensible to clenbuterol concentration of 10-12 g ml-1.

Sex differences and the effects of ovariectomy on the β-adrenergic contractile response

PubMed Central

McIntosh, Victoria J.; Chandrasekera, P. Charukeshi

2011-01-01

The presence of sex differences in myocardial β-adrenergic responsiveness is controversial, and limited studies have addressed the mechanism underlying these differences. Studies were performed using isolated perfused hearts from male, intact female and ovariectomized female mice to investigate sex differences and the effects of ovarian hormone withdrawal on β-adrenergic receptor function. Female hearts exhibited blunted contractile responses to the β-adrenergic receptor agonist isoproterenol (ISO) compared with males but not ovariectomized females. There were no sex differences in β1-adrenergic receptor gene or protein expression. To investigate the role of adenylyl cyclase, phosphodiesterase, and the cAMP-signaling cascade in generating sex differences in the β-adrenergic contractile response, dose-response studies were performed in isolated perfused male and female hearts using forskolin, 3-isobutyl-1-methylxanthine (IBMX), and 8-(4-chlorophenylthio)adenosine 3′,5′-cyclic monophosphate (CPT-cAMP). Males showed a modestly enhanced contractile response to forskolin at 300 nM and 5 μM compared with females, but there were no sex differences in the response to IBMX or CPT-cAMP. The role of the A1 adenosine receptor (A1AR) in antagonizing the β-adrenergic contractile response was investigated using both the A1AR agonist 2-chloro-N6-cyclopentyl-adenosine and A1AR knockout (KO) mice. Intact females showed an enhanced A1AR anti-adrenergic effect compared with males and ovariectomized females. The β-adrenergic contractile response was potentiated in both male and female A1ARKO hearts, with sex differences no longer present above 1 nM ISO. The β-adrenergic contractile response is greater in male hearts than females, and minor differences in the action of adenylyl cyclase or the A1AR may contribute to these sex differences. PMID:21685268

Noradrenaline, oxymetazoline and phorbol myristate acetate induce distinct functional actions and phosphorylation patterns of α1A-adrenergic receptors.

PubMed

Alcántara-Hernández, Rocío; Hernández-Méndez, Aurelio; Romero-Ávila, M Teresa; Alfonzo-Méndez, Marco A; Pupo, André S; García-Sáinz, J Adolfo

2017-12-01

In LNCaP cells that stably express α 1A -adrenergic receptors, oxymetazoline increased intracellular calcium and receptor phosphorylation, however, this agonist was a weak partial agonist, as compared to noradrenaline, for calcium signaling. Interestingly, oxymetazoline-induced receptor internalization and desensitization displayed greater effects than those induced by noradrenaline. Phorbol myristate acetate induced modest receptor internalization and minimal desensitization. α 1A -Adrenergic receptor interaction with β-arrestins (colocalization/coimmunoprecipitation) was induced by noradrenaline and oxymetazoline and, to a lesser extent, by phorbol myristate acetate. Oxymetazoline was more potent and effective than noradrenaline in inducing ERK 1/2 phosphorylation. Mass spectrometric analysis of immunopurified α 1A -adrenergic receptors from cells treated with adrenergic agonists and the phorbol ester clearly showed that phosphorylated residues were present both at the third intracellular loop and at the carboxyl tail. Distinct phosphorylation patterns were observed under the different conditions. The phosphorylated residues were: a) Baseline and all treatments: T233; b) noradrenaline: S220, S227, S229, S246, S250, S389; c) oxymetazoline: S227, S246, S381, T384, S389; and d) phorbol myristate acetate: S246, S250, S258, S351, S352, S401, S402, S407, T411, S413, T451. Our novel data, describing the α 1A -AR phosphorylation sites, suggest that the observed different phosphorylation patterns may participate in defining adrenoceptor localization and action, under the different conditions examined. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Identification of Buctopamine and Mebuctopamine, a β2 Receptor Agonist and Its Metabolite, in Swine Hair and Feed Additives.

PubMed

Chen, Ying-Heng; Yang, Chia-Ying; Cheng, Chih Wen; Lin, Yi-Ying; Kuo, Su Lien; Hsin, Ling-Wei

2017-05-17

4-[2-(t-Butylamino)-1-hydroxyethyl]phenol (buctopamine, 4), a new β 2 receptor agonist (β 2 -agonist), was found to be an adulterant in feed additives for swine in Taiwan, where using β 2 -agonists in food-production animals is prohibited. Buctopamine and its metabolite, 4-[2-(t-butylamino)-1-hydroxyethyl]-2-methoxyphenol (mebuctopamine, 2), were detected in swine hair specimens. Authentic compounds 2 and 4 were synthesized with 98.6% and 97.7% purity, respectively, as reference standards for analysis, and both compounds were more hydrophilic than ractopamine and clenbuterol. In a preliminary pharmacological evaluation, compounds 2 and 4 exhibited moderate human β 2 receptor binding affinity and did not show significant affinities for the human α 1 , α 2 , β 1 , and β 3 receptors. After addition of compounds 2-4 into the β 2 -agonist library, a multiresidue analysis of 26 β 2 -agonists by using triple quadrupole LC/MS/MS for routine screening conducted by regulatory authorities was established, in which the common limits of quantification for the 26 β 2 -agonists in swine feed and hair are 10 and 25 ng/g, respectively. In addition, the illegal use of buctopamine (4) has been effectively prevented. The results of this study are also useful for controlling the illegal use of new β 2 -agonists in food-production animals.

[What illegal substances are used by sportsmen? a study in Midi-Pyrénées Doping Preventing Medical Centre (AMPD-MP)].

PubMed

Senard-Ojero, Ana; Durrieu, Geneviève; Depiesse, Frédéric; Schmitt, Laurent; Riviere, Daniel; Montastruc, Jean-Louis

2010-01-01

Doping Preventing Medical Centres (Antennes Médicales de Prévention du Dopage) were established in France in 2000 in order to help sportsmen using illegal substances. These services are also information centres on illegal substances (drugs or others) used in sport. The aim of the study was to analyze the characteristics of sportsmen outpatient clinics in Antenne Médicale de Prevention du Dopage Midi-Pyrénées (AMPD-MP). We present the results of outpatient clinics in AMPD-MP from 2002 to 2008. A descriptive analysis of demographic data, substances used and sports practised were performed. During this 7 year-period, 35 outpatient clinics were performed [32 men, 3 women, mean age: 28 years (extreme values: 18-47; 10 patients ≥ 30 years)]. They were mainly involved in national (16), international (8) or regional (7) competitions. The main sports involved were rugby (9) followed by cycling (5), athletics (3) and body-building (3). The most frequently used illegal substances were cannabis (15) followed by glucocorticoïds (9), androgens (4), indirect sympathomimetics amphetaminics (4), beta 2 adrenergic agonists (2) and NSAIDs (2). Two veterinary substances (clenbuterol, boldone-veterinaire) were also found in body-builders. This study shows a clear under use of Doping Preventing Medical Centres by sportsmen and practitioners. It also indicates a relative high age for sportsmen referred to the centre. The main sports involved were rugby and cycling. Cannabis and glucocorticoïds were the drugs more often involved in doping behaviours.

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

Decreased hepatic response to glucagon, adrenergic agonists, and cAMP in glycogenolysis, gluconeogenesis, and glycolysis in tumor-bearing rats.

PubMed

Biazi, Giuliana R; Frasson, Isabele G; Miksza, Daniele R; de Morais, Hely; de Fatima Silva, Flaviane; Bertolini, Gisele L; de Souza, Helenir M

2018-05-15

The response to glucagon and adrenaline in cancer cachexia is poorly known. The aim of this study was to investigate the response to glucagon, adrenergic agonists (α and β) and cyclic adenosine monophosphate (cAMP) on glycogenolysis, gluconeogenesis, and glycolysis in liver perfusion of Walker-256 tumor-bearing rats with advanced cachexia. Liver ATP content was also investigated. Rats without tumor (healthy) were used as controls. Agonists α (phenylephrine) and β (isoproterenol) adrenergic, instead of adrenaline, and cAMP, the second messenger of glucagon and isoproterenol, were used in an attempt to identify mechanisms involved in the responses. Glucagon (1 nM) stimulated glycogenolysis and gluconeogenesis and inhibited glycolysis in the liver of healthy and tumor-bearing rats, but their effects were lower in tumor-bearing rats. Isoproterenol (20 µM) stimulated glycogenolysis, gluconeogenesis, and glycolysis in healthy rats and had virtually no effect in tumor-bearing rats. cAMP (9 µM) also stimulated glycogenolysis and gluconeogenesis and inhibited glycolysis in healthy rats but had practically no effect in tumor-bearing rats. Phenylephrine (2 µM) stimulated glycogenolysis and gluconeogenesis and inhibited glycolysis and these effects were also lower in tumor-bearing rats than in healthy. Liver ATP content was lower in tumor-bearing rats. In conclusion, tumor-bearing rats with advanced cachexia showed a decreased hepatic response to glucagon, adrenergic agonists (α and β), and cAMP in glycogenolysis, gluconeogenesis, and glycolysis, which may be due to a reduced rate of regulatory enzyme phosphorylation caused by the low ATP levels in the liver. © 2018 Wiley Periodicals, Inc.

Lateral saphenous vein responses to serotonergic and a-adrenergic receptor agonists increase with time off endophyte-infected tall fescue

USDA-ARS?s Scientific Manuscript database

Previous research has indicated that serotonergic and a-adrenergic receptors in peripheral vasculature are affected by exposure of cattle grazing toxic endophyte-infected (E+) tall fescue (TF; Lolium arundinaceum). This study was conducted to investigate changes in vascular contractile response over...

Norepinephrine Triggers Metaplasticity of LTP by Increasing Translation of Specific mRNAs

ERIC Educational Resources Information Center

Maity, Sabyasachi; Rah, Sean; Sonenberg, Nahum; Gkogkas, Christos G.; Nguyen, Peter V.

2015-01-01

Norepinephrine (NE) is a key modulator of synaptic plasticity in the hippocampus, a brain structure crucially involved in memory formation. NE boosts synaptic plasticity mostly through initiation of signaling cascades downstream from beta (ß)-adrenergic receptors (ß-ARs). Previous studies demonstrated that a ß-adrenergic receptor agonist,…

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.

Historical Overview of the Effect of β-Adrenergic Agonists on Beef Cattle Production

PubMed Central

Johnson, Bradley J.; Smith, Stephen B.; Chung, Ki Yong

2014-01-01

Postnatal muscle hypertrophy of beef cattle is the result of enhanced myofibrillar protein synthesis and reduced protein turnover. Skeletal muscle hypertrophy has been studied in cattle fed β-adrenergic agonists (β-AA), which are receptor-mediated enhancers of protein synthesis and inhibitors of protein degradation. Feeding β-AA to beef cattle increases longissimus muscle cross-sectional area 6% to 40% compared to non-treated cattle. The β-AA have been reported to improve live animal performance, including average daily gain, feed efficiency, hot carcass weight, and dressing percentage. Treatment with β-AA increased mRNA concentration of the β2 or β1-adrenergic receptor and myosin heavy chain IIX in bovine skeletal muscle tissue. This review will examine the effects of skeletal muscle and adipose development with β-AA, and will interpret how the use of β-AA affects performance, body composition, and growth in beef cattle. PMID:25050012

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

Agonist-induced conformational changes in the G-protein-coupling domain of the β2 adrenergic receptor

PubMed Central

Ghanouni, Pejman; Steenhuis, Jacqueline J.; Farrens, David L.; Kobilka, Brian K.

2001-01-01

The majority of extracellular physiologic signaling molecules act by stimulating GTP-binding protein (G-protein)-coupled receptors (GPCRs). To monitor directly the formation of the active state of a prototypical GPCR, we devised a method to site specifically attach fluorescein to an endogenous cysteine (Cys-265) at the cytoplasmic end of transmembrane 6 (TM6) of the β2 adrenergic receptor (β2AR), adjacent to the G-protein-coupling domain. We demonstrate that this tag reports agonist-induced conformational changes in the receptor, with agonists causing a decline in the fluorescence intensity of fluorescein-β2AR that is proportional to the biological efficacy of the agonist. We also find that agonists alter the interaction between the fluorescein at Cys-265 and fluorescence-quenching reagents localized to different molecular environments of the receptor. These observations are consistent with a rotation and/or tilting of TM6 on agonist activation. Our studies, when compared with studies of activation in rhodopsin, indicate a general mechanism for GPCR activation; however, a notable difference is the relatively slow kinetics of the conformational changes in the β2AR, which may reflect the different energetics of activation by diffusible ligands. PMID:11353823

Intranasal dexmedetomidine for adrenergic crisis in familial dysautonomia.

PubMed

Spalink, Christy L; Barnes, Erin; Palma, Jose-Alberto; Norcliffe-Kaufmann, Lucy; Kaufmann, Horacio

2017-08-01

To report the use of intranasal dexmedetomidine, an α 2 -adrenergic agonist for the acute treatment of refractory adrenergic crisis in patients with familial dysautonomia. Case series. Three patients with genetically confirmed familial dysautonomia (case 1: 20-year-old male; case 2: 43-year-old male; case 3: 26-year-old female) received intranasal dexmedetomidine 2 mcg/kg, half of the dose in each nostril, for the acute treatment of adrenergic crisis. Within 8-17 min of administering the intranasal dose, the adrenergic crisis symptoms abated, and blood pressure and heart rate returned to pre-crises values. Adrenergic crises eventually resumed, and all three patients required hospitalization for investigation of the cause of the crises. Intranasal dexmedetomidine is a feasible and safe acute treatment for adrenergic crisis in patients with familial dysautonomia. Further controlled studies are required to confirm the safety and efficacy in this population.

Resolution of R-(-) and S-(+)- enantiomers of clenbuterol in pharmaceutical preparations and black-market products using liquid chromatography-tandem mass spectrometry.

PubMed

Velasco-Bejarano, Benjamín; Bautista, Jahir; Noguez, Ma Olivia; Camacho, Evangelina; Rodríguez, Martha E; Rodríguez, Leonardo

2017-11-01

Several banned substances are illegally used by athletes in racemic mixtures for performance enhancement. These include clenbuterol, methyl hexaneamine, methamphetamines, and amphetamines. Clenbuterol is present in a large number of doping samples from Olympic and non-Olympic athletes that have adverse analytical findings (AAFs). In some cases, the presence of these substances could be the result of consumption of meat contaminated with clenbuterol. In other cases, the origin is not clear. In this study, 27 products with racemic clenbuterol were evaluated using a new analytical methodology for the resolution of R-(-) and S-(+)-enantiomers of clenbuterol by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a chiral column in 15 min with good separation. The method developed can also be used for the analysis of other biological matrices such as urine, serum, and meat. The resolution between two peaks' (R s ) value obtained using chromatographic data was 1.03. Both clenbuterol enantiomers were present in all products analyzed and the ratio was nearly 1. The origin of the product was not important for determining the presence of one or both enantiomers. All products displayed a 50:50 ratio of clenbuterol enantiomers. To the best of our knowledge, clenbuterol ratio determination of a large number of pharmaceutical preparations and black-market products has not been reported previously. The information shown could be used by national anti-doping organizations and the athletes with AAFs attributed to clenbuterol. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

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

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

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

1987-03-01

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

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

Heterologous desensitization of cardiac β-adrenergic signal via hormone-induced βAR/arrestin/PDE4 complexes

PubMed Central

Shi, Qian; Li, Minghui; Mika, Delphine; Fu, Qin; Kim, Sungjin; Phan, Jason; Shen, Ao; Vandecasteele, Gregoire; Xiang, Yang K.

2017-01-01

Aims Cardiac β-adrenergic receptor (βAR) signalling is susceptible to heterologous desensitization by different neurohormonal stimuli in clinical conditions associated with heart failure. We aim to examine the underlying mechanism of cross talk between βARs and a set of G-protein coupled receptors (GPCRs) activated by hormones/agonists. Methods and results Rat ventricular cardiomyocytes were used to determine heterologous phosphorylation of βARs under a series of GPCR agonists. Activation of Gs-coupled dopamine receptor, adenosine receptor, relaxin receptor and prostaglandin E2 receptor, and Gq-coupled α1 adrenergic receptor and angiotensin II type 1 receptor promotes phosphorylation of β1AR and β2AR at putative protein kinase A (PKA) phosphorylation sites; but activation of Gi-coupled α2 adrenergic receptor and activation of protease-activated receptor does not. The GPCR agonists that promote β2AR phosphorylation effectively inhibit βAR agonist isoproterenol-induced PKA phosphorylation of phospholamban and contractile function in ventricular cardiomyocytes. Heterologous GPCR stimuli have minimal to small effect on isoproterenol-induced β2AR activation and G-protein coupling for cyclic adenosine monophosphate (cAMP) production. However, these GPCR stimuli significantly promote phosphorylation of phosphodiesterase 4D (PDE4D), and recruit PDE4D to the phosphorylated β2AR in a β-arrestin 2 dependent manner without promoting β2AR endocytosis. The increased binding between β2AR and PDE4D effectively hydrolyzes cAMP signal generated by subsequent stimulation with isoproterenol. Mutation of PKA phosphorylation sites in β2AR, inhibition of PDE4, or genetic ablation of PDE4D or β-arrestin 2 abolishes this heterologous inhibitory effect. Ablation of β-arrestin 2 or PDE4D gene also rescues β-adrenergic stimuli-induced myocyte contractile function. Conclusions These data reveal essential roles of β-arrestin 2 and PDE4D in a common mechanism for heterologous desensitization of cardiac βARs under hormonal stimulation, which is associated with impaired cardiac function during the development of pathophysiological conditions. PMID:28339772

Heterologous desensitization of cardiac β-adrenergic signal via hormone-induced βAR/arrestin/PDE4 complexes.

PubMed

Shi, Qian; Li, Minghui; Mika, Delphine; Fu, Qin; Kim, Sungjin; Phan, Jason; Shen, Ao; Vandecasteele, Gregoire; Xiang, Yang K

2017-05-01

Cardiac β-adrenergic receptor (βAR) signalling is susceptible to heterologous desensitization by different neurohormonal stimuli in clinical conditions associated with heart failure. We aim to examine the underlying mechanism of cross talk between βARs and a set of G-protein coupled receptors (GPCRs) activated by hormones/agonists. Rat ventricular cardiomyocytes were used to determine heterologous phosphorylation of βARs under a series of GPCR agonists. Activation of Gs-coupled dopamine receptor, adenosine receptor, relaxin receptor and prostaglandin E2 receptor, and Gq-coupled α1 adrenergic receptor and angiotensin II type 1 receptor promotes phosphorylation of β1AR and β2AR at putative protein kinase A (PKA) phosphorylation sites; but activation of Gi-coupled α2 adrenergic receptor and activation of protease-activated receptor does not. The GPCR agonists that promote β2AR phosphorylation effectively inhibit βAR agonist isoproterenol-induced PKA phosphorylation of phospholamban and contractile function in ventricular cardiomyocytes. Heterologous GPCR stimuli have minimal to small effect on isoproterenol-induced β2AR activation and G-protein coupling for cyclic adenosine monophosphate (cAMP) production. However, these GPCR stimuli significantly promote phosphorylation of phosphodiesterase 4D (PDE4D), and recruit PDE4D to the phosphorylated β2AR in a β-arrestin 2 dependent manner without promoting β2AR endocytosis. The increased binding between β2AR and PDE4D effectively hydrolyzes cAMP signal generated by subsequent stimulation with isoproterenol. Mutation of PKA phosphorylation sites in β2AR, inhibition of PDE4, or genetic ablation of PDE4D or β-arrestin 2 abolishes this heterologous inhibitory effect. Ablation of β-arrestin 2 or PDE4D gene also rescues β-adrenergic stimuli-induced myocyte contractile function. These data reveal essential roles of β-arrestin 2 and PDE4D in a common mechanism for heterologous desensitization of cardiac βARs under hormonal stimulation, which is associated with impaired cardiac function during the development of pathophysiological conditions. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.

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

Memory-influencing intra-basolateral amygdala drug infusions modulate expression of Arc protein in the hippocampus.

PubMed

McIntyre, Christa K; Miyashita, Teiko; Setlow, Barry; Marjon, Kristopher D; Steward, Oswald; Guzowski, John F; McGaugh, James L

2005-07-26

Activation of beta-adrenoceptors in the basolateral complex of the amygdala (BLA) modulates memory storage processes and long-term potentiation in downstream targets of BLA efferents, including the hippocampus. Here, we show that this activation also increases hippocampal levels of activity-regulated cytoskeletal protein (Arc), an immediate-early gene (also termed Arg 3.1) implicated in hippocampal synaptic plasticity and memory consolidation processes. Infusions of the beta-adrenoreceptor agonist, clenbuterol, into the BLA immediately after training on an inhibitory avoidance task enhanced memory tested 48 h later. The same dose of clenbuterol significantly increased Arc protein levels in the dorsal hippocampus. Additionally, posttraining intra-BLA infusions of a memory-impairing dose of lidocaine significantly reduced Arc protein levels in the dorsal hippocampus. Increases in Arc protein levels were not accompanied by increases in Arc mRNA, suggesting that amygdala modulation of Arc protein and synaptic plasticity in efferent brain regions occurs at a posttranscriptional level. Finally, infusions of Arc antisense oligodeoxynucleotides into the dorsal hippocampus impaired performance of an inhibitory avoidance task, indicating that the changes in Arc protein expression are related to the observed changes in memory performance.

Memory-influencing intra-basolateral amygdala drug infusions modulate expression of Arc protein in the hippocampus

PubMed Central

McIntyre, Christa K.; Miyashita, Teiko; Setlow, Barry; Marjon, Kristopher D.; Steward, Oswald; Guzowski, John F.; McGaugh, James L.

2005-01-01

Activation of β-adrenoceptors in the basolateral complex of the amygdala (BLA) modulates memory storage processes and long-term potentiation in downstream targets of BLA efferents, including the hippocampus. Here, we show that this activation also increases hippocampal levels of activity-regulated cytoskeletal protein (Arc), an immediate-early gene (also termed Arg 3.1) implicated in hippocampal synaptic plasticity and memory consolidation processes. Infusions of the β-adrenoreceptor agonist, clenbuterol, into the BLA immediately after training on an inhibitory avoidance task enhanced memory tested 48 h later. The same dose of clenbuterol significantly increased Arc protein levels in the dorsal hippocampus. Additionally, posttraining intra-BLA infusions of a memory-impairing dose of lidocaine significantly reduced Arc protein levels in the dorsal hippocampus. Increases in Arc protein levels were not accompanied by increases in Arc mRNA, suggesting that amygdala modulation of Arc protein and synaptic plasticity in efferent brain regions occurs at a posttranscriptional level. Finally, infusions of Arc antisense oligodeoxynucleotides into the dorsal hippocampus impaired performance of an inhibitory avoidance task, indicating that the changes in Arc protein expression are related to the observed changes in memory performance. PMID:16020527

The deubiquitinases USP33 and USP20 coordinate beta2 adrenergic receptor recycling and resensitization.

PubMed

Berthouze, Magali; Venkataramanan, Vidya; Li, Yi; Shenoy, Sudha K

2009-06-17

Agonist-induced ubiquitination of the beta(2) adrenergic receptor (beta(2)AR) functions as an important post-translational modification to sort internalized receptors to the lysosomes for degradation. We now show that this ubiquitination is reversed by two deubiquitinating enzymes, ubiquitin-specific proteases (USPs) 20 and 33, thus, inhibiting lysosomal trafficking when concomitantly promoting receptor recycling from the late-endosomal compartments as well as resensitization of recycled receptors at the cell surface. Dissociation of constitutively bound endogenously expressed USPs 20 and 33 from the beta(2)AR immediately after agonist stimulation and reassociation on prolonged agonist treatment allows receptors to first become ubiquitinated and then deubiquitinated, thus, providing a 'trip switch' between degradative and recycling pathways at the late-endosomal compartments. Thus, USPs 20 and 33 serve as novel regulators that dictate both post-endocytic sorting as well as the intensity and extent of beta(2)AR signalling from the cell surface.

Vitamin D increases plasma renin activity independently of plasma Ca2+ via hypovolemia and β-adrenergic activity

PubMed Central

Atchison, Douglas K.; Harding, Pamela

2013-01-01

1, 25-Dihydroxycholechalciferol (calcitriol) and 19-nor-1, 25-dihydroxyvitamin D2 (paricalcitol) are vitamin D receptor (VDR) agonists. Previous data suggest VDR agonists may actually increase renin-angiotensin activity, and this has always been assumed to be mediated by hypercalcemia. We hypothesized that calcitriol and paricalcitol would increase plasma renin activity (PRA) independently of plasma Ca2+ via hypercalciuria-mediated polyuria, hypovolemia, and subsequent increased β-adrenergic sympathetic activity. We found that both calcitriol and paricalcitol increased PRA threefold (P < 0.01). Calcitriol caused hypercalcemia, but paricalcitol did not. Both calcitriol and paricalcitol caused hypercalciuria (9- and 7-fold vs. control, P < 0.01) and polyuria (increasing 2.6- and 2.2-fold vs. control, P < 0.01). Paricalcitol increased renal calcium-sensing receptor (CaSR) expression, suggesting a potential cause of paricalcitol-mediated hypercalciuria and polyuria. Volume replacement completely normalized calcitriol-stimulated PRA and lowered plasma epinephrine by 43% (P < 0.05). β-Adrenergic blockade also normalized calcitriol-stimulated PRA. Cyclooxygenase-2 inhibition had no effect on calcitriol-stimulated PRA. Our data demonstrate that vitamin D increases PRA independently of plasma Ca2+ via hypercalciuria, polyuria, hypovolemia, and increased β-adrenergic activity. PMID:23926179

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.

Bone marrow adipocytes resist lipolysis and remodeling in response to β-adrenergic stimulation.

PubMed

Scheller, Erica L; Khandaker, Shaima; Learman, Brian S; Cawthorn, William P; Anderson, Lindsay M; Pham, H A; Robles, Hero; Wang, Zhaohua; Li, Ziru; Parlee, Sebastian D; Simon, Becky R; Mori, Hiroyuki; Bree, Adam J; Craft, Clarissa S; MacDougald, Ormond A

2018-01-26

Bone marrow adipose tissue (BMAT) is preserved or increased in states of caloric restriction. Similarly, we found that BMAT in the tail vertebrae, but not the red marrow in the tibia, resists loss of neutral lipid with acute, 48-hour fasting in rats. The mechanisms underlying this phenomenon and its seemingly distinct regulation from peripheral white adipose tissue (WAT) remain unknown. To test the role of β-adrenergic stimulation, a major regulator of adipose tissue lipolysis, we examined the responses of BMAT to β-adrenergic agonists. Relative to inguinal WAT, BMAT had reduced phosphorylation of hormone sensitive lipase (HSL) after treatment with pan-β-adrenergic agonist isoproterenol. Phosphorylation of HSL in response to β3-adrenergic agonist CL316,243 was decreased by an additional ~90% (distal tibia BMAT) or could not be detected (tail vertebrae). Ex vivo, adrenergic stimulation of lipolysis in purified BMAT adipocytes was also substantially less than iWAT adipocytes and had site-specific properties. Specifically, regulated bone marrow adipocytes (rBMAs) from proximal tibia and femur underwent lipolysis in response to both CL316,243 and forskolin, while constitutive BMAs from the tail responded only to forskolin. This occurred independently of changes in gene expression of β-adrenergic receptors, which were similar between adipocytes from iWAT and BMAT, and could not be explained by defective coupling of β-adrenergic receptors to lipolytic machinery through caveolin 1. Specifically, we found that whereas caveolin 1 was necessary to mediate maximal stimulation of lipolysis in iWAT, overexpression of caveolin 1 was insufficient to rescue impaired BMAT signaling. Lastly, we tested the ability of BMAT to respond to 72-hour treatment with CL316,243 in vivo. This was sufficient to cause beiging of iWAT adipocytes and a decrease in iWAT adipocyte cell size. By contrast, adipocyte size in the tail BMAT and distal tibia remained unchanged. However, within the distal femur, we identified a subpopulation of BMAT adipocytes that underwent lipid droplet remodeling. This response was more pronounced in females than in males and resembled lipolysis-induced lipid partitioning rather than traditional beiging. In summary, BMAT has the capacity to respond to β-adrenergic stimuli, however, its responses are muted and BMAT generally resists lipid hydrolysis and remodeling relative to iWAT. This resistance is more pronounced in distal regions of the skeleton where the BMAT adipocytes are larger with little intervening hematopoiesis, suggesting that there may be a role for both cell-autonomous and microenvironmental determinants. Resistance to β-adrenergic stimuli further separates BMAT from known regulators of energy partitioning and contributes to our understanding of why BMAT is preserved in states of fasting and caloric restriction. Copyright © 2018 Elsevier Inc. All rights reserved.

Triiodothyronine, beta-adrenergic receptors, agonist responses, and exercise capacity.

PubMed

Martin, W H

1993-07-01

Although thyroid hormone excess results in increased beta-adrenergic receptor density or agonist responses in some cells of experimental animals, the role of these effects in contributing to clinical manifestations of hyperthyroidism in human subjects is unclear. To shed further light on this issue, we characterized the effect of 2 weeks of excess triiodothyronine administration on cardiac and metabolic responses to graded-dose isoproterenol infusion, skeletal muscle beta-adrenergic receptor density, and physiologic determinants of exercise capacity in young healthy subjects. The slope of the heart rate response to isoproterenol was 36% greater (p < 0.05) after triiodothyronine administration. In addition, beta-adrenergic receptor density was increased (p < 0.01) in all types of skeletal muscle fibers. Maximal oxygen uptake during treadmill exercise declined 5% (p < 0.001) after triiodothyronine administration because of a decrease in the arteriovenous oxygen difference (p < 0.05). The plasma lactate response to submaximal exercise was 25% greater (p < 0.01) in the hyperthyroid state. These effects were paralleled by a decrement in skeletal muscle oxidative capacity and a decrease in cross-sectional area of type 2A skeletal myocytes. Thus, thyroid hormone excess enhances cardiac beta-adrenergic sensitivity under in vivo conditions in human subjects. Nevertheless, exercise capacity is diminished in the hyperthyroid state, an effect that may be related to reduced skeletal muscle oxidative capacity and type 2A fiber atrophy.

Cholesterol regulates contractility and inotropic response to β2-adrenoceptor agonist in the mouse atria: Involvement of Gi-protein-Akt-NO-pathway.

PubMed

Odnoshivkina, Yulia G; Sytchev, Vaycheslav I; Petrov, Alexey M

2017-06-01

Majority of cardiac β2-adrenoceptors is located in cholesterol-rich microdomains. Here, we have investigated the underlying mechanisms by which a slight to moderate cholesterol depletion with methyl-β-cyclodextrin (MβCD, 1 and 5mM) interferes with contractility and inotropic effect of β2-adrenergic agonist (fenoterol, 50μM) in the mouse atria. Treatment with MβCD itself increased amplitude of Ca 2+ transient but did not change the contraction amplitude due to a clamping action of elevated NO. Cholesterol depletion significantly attenuated the positive inotropic response to fenoterol which is accompanied by increase in NO generation and decrease in Ca 2+ transient. Influence of 1mM MβCD on the fenoterol-driven changes in both contractility and NO level was strongly attenuated by inhibition of G i -protein (pertussis toxin), Akt (Akt 1/2 kinase inhibitor) or NO-synthase (L-NAME). After exposure to 5mM MβCD, pertussis toxin or Akt inhibitor could recover the β2-agonist effects on contractility, NO production and Ca 2+ transient, while L-NAME only reduced NO level. An adenylyl cyclase activator (forskolin, 50nM) had no influence on the MβCD-induced changes in the β2-agonist effects. Obtained results suggest that slight cholesterol depletion upregulates G i -protein/Akt/NO-synthase signaling that attenuates the positive inotropic response to β2-adrenergic stimulation without altering the Ca 2+ transient. Whilst moderate cholesterol depletion additionally could suppress the enhancement of the Ca 2+ transient amplitude caused by the β2-adrenergic agonist administration in G i -protein/Akt-dependent but NO-independent manner. Copyright © 2016 Elsevier Ltd. All rights reserved.

The beta-adrenergic agonist salbutamol modulates neuromuscular junction formation in zebrafish models of human myasthenic syndromes.

PubMed

McMacken, Grace; Cox, Dan; Roos, Andreas; Müller, Juliane; Whittaker, Roger; Lochmüller, Hanns

2018-05-01

Inherited defects of the neuromuscular junction (NMJ) comprise an increasingly diverse range of disorders, termed congenital myasthenic syndromes (CMS). Therapies acting on the sympathetic nervous system, including the selective β2 adrenergic agonist salbutamol and the α and β adrenergic agonist ephedrine, have become standard treatment for several types of CMS. However, the mechanism of the therapeutic effect of sympathomimetics in these disorders is not understood. Here, we examined the effect of salbutamol on NMJ development using zebrafish with deficiency of the key postsynaptic proteins Dok-7 and MuSK. Treatment with salbutamol reduced motility defects in zebrafish embryos and larvae. In addition, salbutamol lead to morphological improvement of postsynaptic acetycholine receptor (AChR) clustering and size of synaptic contacts in Dok-7-deficient zebrafish. In MuSK-deficient zebrafish, salbutamol treatment reduced motor axon pathfinding defects and partially restored the formation of aneural prepatterned AChRs. In addition, the effects of salbutamol treatment were prevented by pre-treatment with a selective β2 antagonist. Treatment with the cyclic adenosine monophosphate (cAMP) activator forskolin, replicated the effects of salbutamol treatment. These results suggest that sympathomimetics exert a direct effect on neuromuscular synaptogenesis and do so via β2 adrenoceptors and via a cAMP-dependent pathway.

The beta-adrenergic agonist salbutamol modulates neuromuscular junction formation in zebrafish models of human myasthenic syndromes

PubMed Central

McMacken, Grace; Cox, Dan; Roos, Andreas; Müller, Juliane; Whittaker, Roger; Lochmüller, Hanns

2018-01-01

Abstract Inherited defects of the neuromuscular junction (NMJ) comprise an increasingly diverse range of disorders, termed congenital myasthenic syndromes (CMS). Therapies acting on the sympathetic nervous system, including the selective β2 adrenergic agonist salbutamol and the α and β adrenergic agonist ephedrine, have become standard treatment for several types of CMS. However, the mechanism of the therapeutic effect of sympathomimetics in these disorders is not understood. Here, we examined the effect of salbutamol on NMJ development using zebrafish with deficiency of the key postsynaptic proteins Dok-7 and MuSK. Treatment with salbutamol reduced motility defects in zebrafish embryos and larvae. In addition, salbutamol lead to morphological improvement of postsynaptic acetycholine receptor (AChR) clustering and size of synaptic contacts in Dok-7-deficient zebrafish. In MuSK-deficient zebrafish, salbutamol treatment reduced motor axon pathfinding defects and partially restored the formation of aneural prepatterned AChRs. In addition, the effects of salbutamol treatment were prevented by pre-treatment with a selective β2 antagonist. Treatment with the cyclic adenosine monophosphate (cAMP) activator forskolin, replicated the effects of salbutamol treatment. These results suggest that sympathomimetics exert a direct effect on neuromuscular synaptogenesis and do so via β2 adrenoceptors and via a cAMP-dependent pathway. PMID:29462491

Characterization and inhibition of beta-adrenergic receptor kinase in intact myocytes.

PubMed

Laugwitz, K L; Kronsbein, K; Schmitt, M; Hoffmann, K; Seyfarth, M; Schömig, A; Ungerer, M

1997-08-01

beta-Adrenergic receptor kinase (beta ARK) phosphorylates and thereby inactivates agonist-occupied beta-adrenergic receptors (beta AR). beta ARK is thought to play an important role in the regulation of cardiac function. Therefore, we studied beta ARK activation and its inhibition in intact smooth muscle cells and in cardiomyoblasts. beta AR agonist-stimulated translocation of beta ARK was monitored by immunofluorescence labelling with specific antibodies and confocal laser scanning microscopy in DDT-MF 2 hamster smooth muscle cells and in H9c2 rat cardiomyoblasts. In unstimulated cells. beta ARK was mainly located in the cytosol. After beta AR agonist stimulation, the beta ARK signal was partially translocated to the membranes. Liposomal gene transfer of the COOH-terminus of beta ARK ('beta ARKmini') as a beta ARK inhibitor led to functional expression of this protein in both cell lines with high efficiency. Western blots with beta ARK antibodies showed a gene concentration-dependent immunoreactivity of the 'beta ARKmini' protein. 'beta ARKmini'-transfected myocytes demonstrated reduced membrane targeting of the beta ARK immuno-fluorescence signal. Additionally, the effect of 'beta ARKmini' on beta AR-induced desensitization of myocytic cAMP accumulation was investigated. In control cells, desensitization with isoproterenol led to a subsequent reduction of beta AR-induced cAMP accumulation. In 'beta ARKmini'-transfected myocytes, this beta AR-induced desensitization was significantly diminished, whereas normal beta AR-induced cAMP accumulation was unaffected. A gene concentration of 2 micrograms 'beta ARKmini' DNA/100,000 cardiomyoblasts, and of 0.7 microgram 'beta ARKmini' DNA/100,000 DDT-MF2 smooth muscle cells led to approximately 5.9- and approximately 5.6-fold overexpressions of 'beta ARKmini' vs. native beta ARK, respectively. These gene doses proved sufficient to attenuate beta-adrenergic desensitization significantly. (1) beta ARK translocation was evidenced in DDT-MF2 smooth muscle cells and in cardiomyoblasts by confocal laser scanning microscopy. (2) Feasibility of 'beta ARKmini' gene transfer to myocytes was demonstrated, and necessary gene doses for beta ARK inhibition were titered. (3) Overexpression of 'beta ARKmini' functionally interacted with endogenous beta-adrenergic signal transduction, leading to sustained cAMP accumulation after prolonged beta-adrenergic stimulation.

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.

Cross-talk from β-Adrenergic Receptors Modulates α2A-Adrenergic Receptor Endocytosis in Sympathetic Neurons via Protein Kinase A and Spinophilin*

PubMed Central

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

2013-01-01

Inter-regulation of adrenergic receptors (ARs) via cross-talk is a long appreciated but mechanistically unclear physiological phenomenon. Evidence from the AR literature and our own extensive studies on regulation of α2AARs by the scaffolding protein spinophilin have illuminated a potential novel mechanism for cross-talk from β to α2ARs. In the present study, we have characterized a mode of endogenous AR cross-talk in native adrenergic neurons whereby canonical βAR-mediated signaling modulates spinophilin-regulated α2AAR endocytosis through PKA. Our findings demonstrate that co-activation of β and α2AARs, either by application of endogenous agonist or by simultaneous stimulation with distinct selective agonists, results in acceleration of endogenous α2AAR endocytosis in native neurons. We show that receptor-independent PKA activation by forskolin is sufficient to accelerate α2AAR endocytosis and that α2AAR stimulation alone drives accelerated endocytosis in spinophilin-null neurons. Endocytic response acceleration by β/α2AAR co-activation is blocked by PKA inhibition and lost in spinophilin-null neurons, consistent with our previous finding that spinophilin is a substrate for phosphorylation by PKA that disrupts its interaction with α2AARs. Importantly, we show that α2AR agonist-mediated α2AAR/spinophilin interaction is blocked by βAR co-activation in a PKA-dependent fashion. We therefore propose a novel mechanism for cross-talk from β to α2ARs, whereby canonical βAR-mediated signaling coupled to PKA activation results in phosphorylation of spinophilin, disrupting its interaction with α2AARs and accelerating α2AAR endocytic responses. This mechanism of cross-talk has significant implications for endogenous adrenergic physiology and for therapeutic targeting of β and α2AARs. PMID:23965992

Clenbuterol - regional food contamination a possible source for inadvertent doping in sports.

PubMed

Guddat, S; Fußhöller, G; Geyer, H; Thomas, A; Braun, H; Haenelt, N; Schwenke, A; Klose, C; Thevis, M; Schänzer, W

2012-06-01

The misuse of the sympathomimetic and anabolic agent clenbuterol has been frequently reported in professional sport and in the livestock industry. In 2010, a team of athletes returned from competition in China and regular doping control samples were taken within the next two days. All urine samples contained low amounts (pg/ml) of clenbuterol, drawing the attention to a well-known problem: the possibility of an unintended clenbuterol intake with food. A warning that Chinese meat is possibly contaminated with prohibited substances according to international anti-doping regulations was also given by Chinese officials just before the Bejing Olympic Games in 2008. To investigate if clenbuterol can be found in human urine, a study was initiated comprising 28 volunteers collecting urine samples after their return from China. For the quantification of clenbuterol at a low pg/ml level, a very sensitive and specific isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed using liquid/liquid re-extraction for clean-up with a limit of detection and quantification of 1 and 3 pg/ml, respectively. The method was validated demonstrating good precision (intra-day: 2.9-5.5 %; inter-day: 5.1-8.8%), accuracy (89.5-102.5%) and mean recovery (81.4%). Clenbuterol was detectable in 22 (79%) of the analyzed samples, indicating a general food contamination problem despite an official clenbuterol prohibition in China for livestock. Copyright © 2012 John Wiley & Sons, Ltd.

Central beta-adrenergic modulation of cognitive flexibility.

PubMed

Beversdorf, David Q; White, Dawn M; Chever, Daquesha C; Hughes, John D; Bornstein, Robert A

2002-12-20

Situational stressors and anxiety impede performance on creativity tests requiring cognitive flexibility. Preliminary research revealed better performance on a task requiring cognitive flexibility, the anagram task, after propranolol (beta-adrenergic antagonist) than after ephedrine (beta-adrenergic agonist). However, propranolol and ephedrine have both peripheral and central beta-adrenergic effects. In order to determine whether noradrenergic modulation of cognitive flexibility is a centrally or peripherally mediated phenomenon, we compared the effects of propranolol (peripheral and central beta-blocker), nadolol (peripheral beta-blocker), and placebo on anagram task performance. Solution latency scores for each subject were compared across the drug conditions. Anagram solution latency scores after propranolol were significantly lower than after nadolol. This suggests a centrally mediated modulatory influence of the noradrenergic system on cognitive flexibility.

Beta-3 adrenergic agonists reduce pulmonary vascular resistance and improve right ventricular performance in a porcine model of chronic pulmonary hypertension.

PubMed

García-Álvarez, Ana; Pereda, Daniel; García-Lunar, Inés; Sanz-Rosa, David; Fernández-Jiménez, Rodrigo; García-Prieto, Jaime; Nuño-Ayala, Mario; Sierra, Federico; Santiago, Evelyn; Sandoval, Elena; Campelos, Paula; Agüero, Jaume; Pizarro, Gonzalo; Peinado, Víctor I; Fernández-Friera, Leticia; García-Ruiz, José M; Barberá, Joan A; Castellá, Manuel; Sabaté, Manel; Fuster, Valentín; Ibañez, Borja

2016-07-01

Beta-3 adrenergic receptor (β3AR) agonists have been shown to produce vasodilation and prevention of ventricular remodeling in different conditions. Given that these biological functions are critical in pulmonary hypertension (PH), we aimed to demonstrate a beneficial effect of β3AR agonists in PH. An experimental study in pigs (n = 34) with chronic PH created by pulmonary vein banding was designed to evaluate the acute hemodynamic effect and the long-term effect of β3AR agonists on hemodynamics, vascular remodeling and RV performance in chronic PH. Ex vivo human experiments were performed to explore the expression of β3AR mRNA and the vasodilator response of β3AR agonists in pulmonary arteries. Single intravenous administration of the β3AR agonist BRL37344 produced a significant acute reduction in PVR, and two-weeks treatment with two different β3AR selective agonists, intravenous BRL37344 or oral mirabegron, resulted in a significant reduction in PVR (median of -2.0 Wood units/m(2) for BRL37344 vs. +1.5 for vehicle, p = 0.04; and -1.8 Wood units/m(2) for mirabegron vs. +1.6 for vehicle, p = 0.002) associated with a significant improvement in magnetic resonance-measured RV performance. Histological markers of pulmonary vascular proliferation (p27 and Ki67) were significantly attenuated in β3AR agonists-treated pigs. β3AR was expressed in human pulmonary arteries and β3AR agonists produced vasodilatation. β3AR agonists produced a significant reduction in PVR and improved RV performance in experimental PH, emerging as a potential novel approach for treating patients with chronic PH.

Urinary excretion of the ß-adrenergic feed additives ractopamine and zilpaterol in breast and lung cancer patients

USDA-ARS?s Scientific Manuscript database

Background: ß-agonists have been legally used in the U.S. for almost two decades to increase lean muscle mass in meat animals. Despite a cardiotoxic effect after high-dose exposure, there has been limited research on human ß-agonist exposures related to meat consumption. Objectives: We quantified u...

21 CFR 520.452 - Clenbuterol syrup.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Clenbuterol syrup. 520.452 Section 520.452 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.452 Clenbuterol syrup. (a...

21 CFR 520.452 - Clenbuterol syrup.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Clenbuterol syrup. 520.452 Section 520.452 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.452 Clenbuterol syrup. (a...

21 CFR 520.452 - Clenbuterol syrup.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Clenbuterol syrup. 520.452 Section 520.452 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.452 Clenbuterol syrup. (a...

21 CFR 520.452 - Clenbuterol syrup.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Clenbuterol syrup. 520.452 Section 520.452 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.452 Clenbuterol syrup. (a...

21 CFR 520.452 - Clenbuterol syrup.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Clenbuterol syrup. 520.452 Section 520.452 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.452 Clenbuterol syrup. (a...

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 novel brain permeable and G protein-biased beta-1 adrenergic receptor partial agonists for the treatment of neurocognitive disorders

PubMed Central

Yi, Bitna; Jahangir, Alam; Evans, Andrew K.; Briggs, Denise; Ravina, Kristine; Ernest, Jacqueline; Farimani, Amir B.; Sun, Wenchao; Rajadas, Jayakumar; Green, Michael; Feinberg, Evan N.; Pande, Vijay S.

2017-01-01

The beta-1 adrenergic receptor (ADRB1) is a promising therapeutic target intrinsically involved in the cognitive deficits and pathological features associated with Alzheimer’s disease (AD). Evidence indicates that ADRB1 plays an important role in regulating neuroinflammatory processes, and activation of ADRB1 may produce neuroprotective effects in neuroinflammatory diseases. Novel small molecule modulators of ADRB1, engineered to be highly brain permeable and functionally selective for the G protein with partial agonistic activity, could have tremendous value both as pharmacological tools and potential lead molecules for further preclinical development. The present study describes our ongoing efforts toward the discovery of functionally selective partial agonists of ADRB1 that have potential therapeutic value for AD and neuroinflammatory disorders, which has led to the identification of the molecule STD-101-D1. As a functionally selective agonist of ADRB1, STD-101-D1 produces partial agonistic activity on G protein signaling with an EC50 value in the low nanomolar range, but engages very little beta-arrestin recruitment compared to the unbiased agonist isoproterenol. STD-101-D1 also inhibits the tumor necrosis factor α (TNFα) response induced by lipopolysaccharide (LPS) both in vitro and in vivo, and shows high brain penetration. Other than the therapeutic role, this newly identified, functionally selective, partial agonist of ADRB1 is an invaluable research tool to study mechanisms of G protein-coupled receptor signal transduction. PMID:28746336

Discovery of novel brain permeable and G protein-biased beta-1 adrenergic receptor partial agonists for the treatment of neurocognitive disorders.

PubMed

Yi, Bitna; Jahangir, Alam; Evans, Andrew K; Briggs, Denise; Ravina, Kristine; Ernest, Jacqueline; Farimani, Amir B; Sun, Wenchao; Rajadas, Jayakumar; Green, Michael; Feinberg, Evan N; Pande, Vijay S; Shamloo, Mehrdad

2017-01-01

The beta-1 adrenergic receptor (ADRB1) is a promising therapeutic target intrinsically involved in the cognitive deficits and pathological features associated with Alzheimer's disease (AD). Evidence indicates that ADRB1 plays an important role in regulating neuroinflammatory processes, and activation of ADRB1 may produce neuroprotective effects in neuroinflammatory diseases. Novel small molecule modulators of ADRB1, engineered to be highly brain permeable and functionally selective for the G protein with partial agonistic activity, could have tremendous value both as pharmacological tools and potential lead molecules for further preclinical development. The present study describes our ongoing efforts toward the discovery of functionally selective partial agonists of ADRB1 that have potential therapeutic value for AD and neuroinflammatory disorders, which has led to the identification of the molecule STD-101-D1. As a functionally selective agonist of ADRB1, STD-101-D1 produces partial agonistic activity on G protein signaling with an EC50 value in the low nanomolar range, but engages very little beta-arrestin recruitment compared to the unbiased agonist isoproterenol. STD-101-D1 also inhibits the tumor necrosis factor α (TNFα) response induced by lipopolysaccharide (LPS) both in vitro and in vivo, and shows high brain penetration. Other than the therapeutic role, this newly identified, functionally selective, partial agonist of ADRB1 is an invaluable research tool to study mechanisms of G protein-coupled receptor signal transduction.

Pharmacogenetics of the β2-Adrenergic Receptor Gene

PubMed Central

Ortega, Victor E.; Hawkins, Gregory A.; Peters, Stephen P.; Bleecker, Eugene R.

2009-01-01

Asthma is a complex genetic disease with multiple genetic and environmental determinants contributing to the observed variability in response to common anti-asthma therapies. Asthma pharmacogenetic research has focused on multiple candidate genes including the β2-adrenergic receptor gene (ADRβ2) and its effect on individual responses to beta agonist therapy. At present, knowledge about the effects of ADRβ2 variation on therapeutic responses is evolving and should not alter current Asthma Guideline approaches consisting of the use of short acting beta agonists for as-needed symptom based therapy and the use of a regular long-acting beta agonist in combination with inhaled corticosteroid therapy for optimal control of asthma symptoms in those asthmatics who are not controlled on inhaled corticosteroid alone. This approach is based upon studies showing a consistent pharmacogenetic response to regular use of short acting beta agonists (SABA) and less consistent findings in studies evaluating long acting beta agonist (LABA). While emerging pharmacogenetic studies are provocative and should lead to functional approaches, conflicting data with responses to LABA therapy may be caused by factors that include small sample sizes of study populations and differences in experimental design that may limit the conclusions that may be drawn from these clinical trials at the present time. PMID:17996583

Adverse analytical findings with clenbuterol among U-17 soccer players attributed to food contamination issues.

PubMed

Thevis, Mario; Geyer, Lina; Geyer, Hans; Guddat, Sven; Dvorak, Jiri; Butch, Anthony; Sterk, Saskia S; Schänzer, Wilhelm

2013-05-01

The illicit use of growth promoters in animal husbandry has frequently been reported in the past. Among the drugs misused to illegally increase the benefit of stock farming, clenbuterol has held a unique position due to the substance's composition, mechanism of action, metabolism, and disposition. Particularly clenbuterol's disposition in animals' edible tissues destined for food production can cause considerable issues on consumption by elite athletes registered in national and international doping control systems as demonstrated in this case-related study. Triggered by five adverse analytical findings with clenbuterol among the Mexican national soccer team in out-of-competition controls in May 2011, the Fédération Internationale de Football Association (FIFA) initiated an inquest into a potential food contamination (and thus sports drug testing) problem in Mexico, the host country of the FIFA U-17 World Cup 2011. Besides 208 regular doping control samples, which were subjected to highly sensitive mass spectrometric test methods for anabolic agents, 47 meat samples were collected in team hotels during the period of the tournament and forwarded to Institute of Food Safety, RIKILT. In 14 out of 47 meat samples (30%), clenbuterol was detected at concentrations between 0.06 and 11 µg/kg. A total of 109 urine samples out of 208 doping control specimens (52%) yielded clenbuterol findings at concentrations ranging from 1-1556 pg/ml, and only 5 out of 24 teams provided urine samples that did not contain clenbuterol. At least one of these teams was on a strict 'no-meat' diet reportedly due to the known issue of clenbuterol contamination in Mexico. Eventually, owing to the extensive evidence indicating meat contamination as the most plausible reason for the extraordinary high prevalence of clenbuterol findings, none of the soccer players were sanctioned. However, elite athletes have to face severe consequences when testing positive for a prohibited anabolic agent and sufficient supporting information corroborating the scenario of inadvertent ingestion are required to be acquitted from anti-doping rule violations. Hence, governmental contribution is urgently needed to combat the illegal use of clenbuterol in stock breading. Copyright © 2013 John Wiley & Sons, Ltd.

The effect of losartan and carvedilol on vasopressor responses to adrenergic agonists and angiotensin II in the systemic circulation of Sprague Dawley rats.

PubMed

Abdulla, M H; Sattar, M A; Abdullah, N A; Khan, M A H; Anand Swarup, K R L; Johns, E J

2011-01-01

1 Interaction between renin-angiotensin (RAS) and sympathetic nervous systems (SNS) was investigated by examining the effect of cumulative blockade of angiotensin II (Ang II) and adrenergic receptors in normal Sprague Dawley rats. 2 Rats were treated with losartan (10 mg/kg), carvedilol (5 mg/kg), or losartan plus carvedilol (10+5 mg/kg) orally for 7 days. On day 8, the animals were anaesthetized with pentobarbitone and prepared for systemic haemodynamic study. Dose-response relationships for the elevation of mean arterial pressure or change in heart rate (HR) in response to intravenous injections of noradrenaline (NA), phenylephrine (PE), methoxamine (ME) and Ang II were determined. 3 Losartan or the combination of losartan with carvedilol blunted vasopressor responses to ME and Ang II. Dose-response relationships for agonist action on HR were significantly inhibited by all treatments except for the combination of losartan and carvedilol on the decrease in HR induced by PE. Carvedilol decreased vasopressor responses to NA, PE and Ang II, and HR responses to NA, ME and Ang II. Combination treatment produced similar effects to losartan on the vasopressor and HR responses but had a greater effect on vasopressor responses to ME and Ang II, and on HR responses to NA and Ang II than carvedilol alone. 4 It is concluded that peripheral vasoconstriction induced by Ang II is partly mediated by adrenergic action and that the vasopressor responses to adrenergic agonists depend on an intact RAS. These observations suggest an interactive relationship between RAS and SNS in determining systemic haemodynamic responses in 'normal' rats. © 2010 Blackwell Publishing Ltd.

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

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.

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.

Cholinergic inhibition of adrenergic neurosecretion in the rabbit iris-ciliary body

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

Jumblatt, J.E.; North, G.T.

The prejunctional effects of cholinergic agents on release of norepinephrine from sympathetic nerve endings were investigated in the isolated, superfused rabbit iris-ciliary body. Stimulation-evoked release of /sup 3/H-norepinephrine was inhibited by the cholinergic agonists methacholine, oxotremorine, muscarine, carbamylcholine and acetylcholine (plus eserine), but was unmodified by pilocarpine or nicotine. Agonist-induced inhibition was antagonized selectively by atropine, indicating a muscarinic response. Atropine alone markedly enhanced norepinephrine release, revealing considerable tonic activation of prejunctional cholinergic receptors in this system. Prejunctional inhibition by carbamylcholine was found to completely override the facilitative action of forskolin or 8-bromo-cyclic AMP on neurotransmitter release. Cholinergic and alphamore » 2-adrenergic effects on neurosecretion were non-additive, suggesting that the underlying receptors coexist at neurotransmitter release sites.« less

alpha-Adrenergic-mediated activation of human reconstituted fibrinogen receptor (integrin alphaIIbbeta3) in Chinese hamster ovary cells.

PubMed

Butta, Nora; Larrucea, Susana; Gonzalez-Manchon, Consuelo; Alonso, Sonia; Parrilla, Roberto

2004-12-01

This work reports the functional studies of CHO cells coexpressing alpha-adrenergic (alphaAR) and human fibrinogen (Fg) receptors (integrin alphaIIbbeta3). Stimulation of these cells with alpha-agonists produced a transient rise in the free cytosolic calcium (Ca(++)) accompanied by enhanced binding to soluble Fg, and these effects were prevented by specific alphaAR antagonists. The alpha-adrenergic-induced activation of alphaIIbbeta3 in CHO-alphaIIbbeta3-alphaAR increased the rate of adhesion and extension of cells onto Fg coated plates, and also induced a soluble Fg- and alphaIIbbeta3-dependent formation of cell aggregates, whereas no effects were observed by the stimulation of CHO-alphaIIbbeta3 cells. alpha-Adrenergic antagonists, the ligand mimetic peptide RGDS, pertussis toxin (PTX), or EDTA, they all prevented the alpha-adrenergic stimulation of adhesion and aggregation. However, inhibition of PKC prevented the alpha-adrenergic stimulation of cell adherence, whereas blocking the intracellular Ca(++) mobilization impeded the stimulation of cell aggregation. The alpha-adrenergic activation was associated with phosphorylation of a protein of approximately 100 kDa and proteins of the MAPK family. The former was selectively phosphorylated by alpha-adrenergic stimulation whereas the latter were phosphorylated by the binding of cells to Fg and markedly intensified by alpha-adrenergic stimulation.

Breathing and temperature control disrupted by morphine and stabilized by clonidine in neonatal rats.

PubMed

Kesavan, Kalpashri; Ezell, Tarrah; Bierman, Alexis; Nunes, Ana Rita; Northington, Frances J; Tankersley, Clarke G; Gauda, Estelle B

2014-09-15

Sedative-analgesics are often given to newborn infants and are known to affect many components of the autonomic nervous system. While morphine is most frequently used, α-2 adrenergic receptor agonists are being increasingly used in this population. Alpha-2 adrenergic receptors agonists also have anti-shivering properties which may make it a desirable drug to give to infants undergoing therapeutic hypothermia. The aim of this study was to systematically compare two different classes of sedative-analgesics, morphine, a μ-opioid receptor agonist, and clonidine an α-2 adrenergic receptor agonist on breathing, metabolism and core body temperature (CBT) in neonatal rodents. Breathing parameters, oxygen consumption (VO2) and carbon dioxide production (VCO2), were measured prior to, 10 and 90 min after intraperitoneal (IP) administration of morphine (2, 10 or 20 mg/kg), clonidine (40, 200 or 400 μg/kg), or saline in Sprague-Dawley rat pups at postnatal day 7 (p7) while continuously monitoring CBT. Morphine reduced the respiratory rate, VO2 and VCO2 greater than clonidine at all dosages used (p<0.05, morphine vs. clonidine, for all metabolic and respiratory parameters). Furthermore, morphine induced prolonged respiratory pauses, which were not observed in animals treated with clonidine or saline. Morphine caused hypothermia which was dose dependent, while clonidine stabilized CBT in comparison to saline treated animals (p<0.0001). In the newborn rat, morphine causes profound respiratory depression and hypothermia while clonidine causes minimal respiratory depression and stabilizes CBT. All together, we suggest that clonidine promotes autonomic stability and may be a desirable agent to use in infants being treated with therapeutic hypothermia. Copyright © 2014 Elsevier B.V. All rights reserved.

BREATHING AND TEMPERATURE CONTROL DISRUPTED BY MORPHINE AND STABILIZED BY CLONIDINE IN NEONATAL RATS

PubMed Central

Kesavan, Kalpashri; Ezell, Tarrah; Bierman, Alexis; Nunes, Ana Rita; Northington, Frances J.; Tankersley, Clarke G.; Gauda, Estelle B.

2014-01-01

Background Sedative-analgesics are often given to newborn infants and are known to affect many components of the autonomic nervous system. While morphine is most frequently used, α-2 adrenergic receptor agonists are being increasingly used in this population. Alpha-2 adrenergic receptors agonists also have anti-shivering properties which may make it a desirable drug to give to infants undergoing therapeutic hypothermia. The aim of this study was to systematically compare two different classes of sedative-analgesics, morphine, a μ-opioid receptor agonist, and clonidine an α-2 adrenergic receptor agonist on breathing, metabolism and core body temperature (CBT) in neonatal rodents. Methods Breathing parameters, oxygen consumption (VO2) and carbon dioxide production (VCO2), were measured prior to, 10 and 90 minutes after intraperitoneal (IP) administration of morphine (2, 10 or 20mg/kg), clonidine (40, 200 or 400 μg/kg), or saline in Sprague-Dawley rat pups at postnatal day 7 (p7) while continuously monitoring CBT. Results Morphine reduced the respiratory rate, VO2 and VCO2 greater than clonidine at all dosages used (p<0.05, morphine vs. clonidine, for all metabolic and respiratory parameters). Furthermore, morphine induced prolonged respiratory pauses, which were not observed in animals treated with clonidine or saline. Morphine caused hypothermia which was dose dependent, while clonidine stabilized CBT in comparison to saline treated animals (p<0.0001). Conclusion In the newborn rat, morphine causes profound respiratory depression and hypothermia while clonidine causes minimal respiratory depression and stabilizes CBT. All together, we suggest that clonidine promotes autonomic stability and may be a desirable agent to use in infants being treated with therapeutic hypothermia. PMID:25008573

Simulations of Biased Agonists in the β2 Adrenergic Receptor with Accelerated Molecular Dynamics

PubMed Central

2013-01-01

The biased agonism of the G protein-coupled receptors (GPCRs), where in addition to a traditional G protein-signaling pathway a GPCR promotes intracellular signals though β-arrestin, is a novel paradigm in pharmacology. Biochemical and biophysical studies have suggested that a GPCR forms a distinct ensemble of conformations signaling through the G protein and β-arrestin. Here we report on the dynamics of the β2 adrenergic receptor bound to the β-arrestin and G protein-biased agonists and the empty receptor to further characterize the receptor conformational changes caused by biased agonists. We use conventional and accelerated molecular dynamics (aMD) simulations to explore the conformational transitions of the GPCR from the active state to the inactive state. We found that aMD simulations enable monitoring of the transition within the nanosecond time scale while capturing the known microscopic characteristics of the inactive states, such as the ionic lock, the inward position of F6.44, and water clusters. Distinct conformational states are shown to be stabilized by each biased agonist. In particular, in simulations of the receptor with the β-arrestin-biased agonist N-cyclopentylbutanepherine, we observe a different pattern of motions in helix 7 when compared to simulations with the G protein-biased agonist salbutamol that involves perturbations of the network of interactions within the NPxxY motif. Understanding the network of interactions induced by biased ligands and the subsequent receptor conformational shifts will lead to development of more efficient drugs. PMID:23879802

Nitric oxide synthase and cyclooxygenase modulate β-adrenergic cutaneous vasodilatation and sweating in young men.

PubMed

Fujii, Naoto; McNeely, Brendan D; Kenny, Glen P

2017-02-15

β-Adrenergic receptor agonists such as isoproterenol induce cutaneous vasodilatation and sweating in humans, but the mechanisms underpinning this response remain unresolved. Using intradermal microdialysis, we evaluated the roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) in β-adrenergic cutaneous vasodilatation and sweating elicited by administration of isoproterenol. We show that while NOS contributes to β-adrenergic cutaneous vasodilatation, COX restricts cutaneous vasodilatation. We also show that combined inhibition of NOS and COX augments β-adrenergic sweating These new findings advance our basic knowledge regarding the physiological control of cutaneous blood flow and sweating, and provide important and new information to better understand the physiological significance of β-adrenergic receptors in the skin. β-Adrenergic receptor agonists such as isoproterenol can induce cutaneous vasodilatation and sweating in humans, but the mechanisms underpinning this response remain unresolved. We evaluated the hypotheses that (1) nitric oxide synthase (NOS) contributes to β-adrenergic cutaneous vasodilatation, whereas cyclooxygenase (COX) limits the vasodilatation, and (2) COX contributes to β-adrenergic sweating. In 10 young males (25 ± 5 years), cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal forearm skin sites infused with (1) lactated Ringer solution (control), (2) 10 mm N ω -nitro-l-arginine (l-NNA), a non-specific NOS inhibitor, (3) 10 mm ketorolac, a non-specific COX inhibitor, or (4) a combination of l-NNA and ketorolac. All sites were co-administered with a high dose of isoproterenol (100 μm) for 3 min to maximally induce β-adrenergic sweating (β-adrenergic sweating is significantly blunted by subsequent activations). Approximately 60 min after the washout period, three incremental doses of isoproterenol were co-administered (1, 10 and 100 μm each for 25 min). Increases in CVC induced by the first and second 100 μm isoproterenol were attenuated by l-NNA alone, and those in response to all doses of isoproterenol were reduced by l-NNA with co-infusion of ketorolac (all P ≤ 0.05). Ketorolac alone augmented increases in CVC induced by 10 μm and by the second 100 μm isoproterenol (both P ≤ 0.05). While isoproterenol-induced sweating was not affected by the separate administration of l-NNA or ketorolac (all P > 0.05), their combined administration augmented sweating elicited by the first 3 min of 100 μm isoproterenol (P = 0.05). We show that while NOS contributes to β-adrenergic cutaneous vasodilatation, COX restrains the vasodilatation. Finally, combined inhibition of NOS and COX augments β-adrenergic sweating. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

ICI D7114 a novel selective beta-adrenoceptor agonist selectively stimulates brown fat and increases whole-body oxygen consumption.

PubMed Central

Holloway, B. R.; Howe, R.; Rao, B. S.; Stribling, D.; Mayers, R. M.; Briscoe, M. G.; Jackson, J. M.

1991-01-01

1. ICI D7114 is a novel, beta-adrenoceptor agonist which stimulates whole body oxygen consumption in conscious rats, cats and dogs and brown adipose tissue (BAT) activity in conscious rats. Treatment of rats with ICI D7114 stimulated oxygen consumption (ED50, 0.04 mg kg-1, p.o.) and BAT mitochondrial guanosine diphosphate (GDP)-binding (ED50, 0.15 mg kg-1, p.o.) with no chronotropic effects on the heart at these doses. 2. Reference beta-adrenoceptor agonists, isoprenaline and clenbuterol, also stimulated oxygen consumption and BAT activity but were less selective because they also produced effects on heart rate at these doses. 3. Treatment of conscious rats with ICI D7114 did not attenuate the chronotropic effects on the heart of a subsequent isoprenaline challenge. 4. Administration of ICI D7114 or of its acid metabolite had no effect in a cat soleus muscle model of tremor or on blood potassium levels in the conscious dog, indicating lack of effects at beta 2-adrenoceptors. 5. The results indicate that ICI D7114 may have activity at atypical beta-adrenoceptors in brown adipose tissue leading to increased whole body oxygen consumption. PMID:1686210

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.

Mechanisms of L-Triiodothyronine-Induced Inhibition of Synaptosomal Na+-K+-ATPase Activity in Young Adult Rat Brain Cerebral Cortex

PubMed Central

Sarkar, Pradip K.; Biswas, Avijit; Ray, Arun K.; Martin, Joseph V.

2013-01-01

The role of thyroid hormones (TH) in the normal functioning of adult mammalian brain is unclear. Our studies have identified synaptosomal Na+-K+-ATPase as a TH-responsive physiological parameter in adult rat cerebral cortex. L-triiodothyronine (T3) and L-thyroxine (T4) both inhibited Na+-K+-ATPase activity (but not Mg2+-ATPase activity) in similar dose-dependent fashions, while other metabolites of TH were less effective. Although both T3 and the β-adrenergic agonist isoproterenol inhibited Na+-K+-ATPase activity in cerebrocortical synaptosomes in similar ways, the β-adrenergic receptor blocker propranolol did not counteract the effect of T3. Instead, propranolol further inhibited Na+-K+-ATPase activity in a dose-dependent manner, suggesting that the effect of T3 on synaptosomal Na+-K+-ATPase activity was independent of β-adrenergic receptor activation. The effect of T3 on synaptosomal Na+-K+-ATPase activity was inhibited by the α2-adrenergic agonist clonidine and by glutamate. Notably, both clonidine and glutamate activate Gi-proteins of the membrane second messenger system, suggesting a potential mechanism for the inhibition of the effects of TH. In this paper, we provide support for a nongenomic mechanism of action of TH in a neuronal membrane-related energy-linked process for signal transduction in the adult condition. PMID:24307963

Chronic stress accelerates the development of endometriosis in mouse through adrenergic receptor β2.

PubMed

Long, Qiqi; Liu, Xishi; Qi, Qiuming; Guo, Sun-Wei

2016-11-01

Does chronic stress in mice accelerate the development of endometriosis, and, if so, through what mechanism? Exposure to chronic stress accelerates the development of endometriosis and exacerbates the endometriosis-associated generalized hyperalgesia, most likely through activation of the adrenoceptor β2 (ADRB2) and cAMP responsive element-binding protein (CREB). Women with endometriosis tend to have higher levels of psychological stress, which is known to impact negatively on health in general and to promote tumor growth and metastasis in particular. Exposure to chronic stress before and after the induction of endometriosis is reported to increase lesion sizes in rodents, but it is unclear whether adrenoceptors are involved or not in the stress-promoted development of endometriosis. Three independent, prospective, randomized mouse experimentations. A total of 184 virgin female Balb/C mice were used. In Experiment 1, the mice were randomly divided into four groups: the control group, which received no stress; the before, after and both groups, which received immobilization stress before, after and both before and after the induction of endometriosis, respectively. In Experiment 2, mice were randomly divided into four groups one day after the induction of endometriosis: phosphate buffer saline (PBS) and propranolol (PROP) groups, which received the mini-pump containing, respectively, PBS only and propranolol (a non-selective ADRB antagonist) but no stress, STR+PROP and STR+PBS groups, which received stress and the mini-pump containing, respectively, propranolol and PBS. The immobilization stress started after the insertion of mini-pumps. In Experiment 3, mice were induced with endometriosis. Three days after the induction, they were randomly divided into four groups: control, ADRAa, ADRB2a, and ADRBa, which received the mini-pump containing solution only, metaraminol (a non-specific α adrenoceptor agonist), tebutaline (a specific ADRB2 agonist), or isoproterenol (a non-specific ADRB agonist), respectively. In all three experiments, the bodyweight and hotplate latency were evaluated before sacrifice 14 days after the induction. In all experimentations, the lesion weight was evaluated and the harvested ectopic endometrial tissue samples were subjected to immunohistochemistry analysis of vascular endothelial growth factor (VEGF), CD31-positive microvessels, proliferating cell nuclear antigen (PCNA), phosphorylated CREB, ADRB1, ADRB2, ADRB3, adrenergic receptor α1 (ADRA1) and ADRA2. Exposure to chronic stress accelerated the development of endometriosis and exacerbated the endometriosis-associated generalized hyperalgesia. This promotional effect is likely to be mediated through the systemic activation of the sympatho-adreno-medullary (SAM) axis, which results in subsequent release of catecholamines. The surging catecholamines may activate ADRB2 and CREB, yielding increased angiogenesis and cellular proliferation in ectopic endometrium in mice with induced endometriosis. In addition, β adrenergic receptor blockade completely abolished the promotional effect of chronic stress, likely through suppression of ADRB2 and CREB activation, thus suppressing angiogenesis and proliferation. Moreover, a non-specific adrenergic β agonist and a specific adrenergic β2 agonist, but not non-specific adrenergic α agonist, acted similarly to chronic stress, accelerating the development of endometriosis and exacerbating the generalized hyperalgesia in mice with pre-existing endometriosis. NA. This study is limited by the use of immunohistochemistry analyses only and the lack of molecular data. The present study provides the experimental evidence that chronic stress can promote the development of endometriosis through the activation of ADRB2. Given ADRB2 is also expressed in human endometriosis and appears to be functional, and in light of recent awareness that adrenergic signaling plays critical roles in tumorigenesis, it is likely that adrenergic signaling may play important roles in the development of endometriosis and is potentially a target for intervention. This research was supported in part by grants (81270676,  81471434 and 81530040  to S.W.G.;  81370695 and 81671436  to X.S.L.) from the National Natural Science Foundation of China, and grant (2013ZYJB0019 to X.S.L.) from Shanghai Municipal Commission of Health and Family Planning. None of the authors has anything to disclose. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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).

Prenatal exposure to methyldopa leading to hypertensive crisis and cardiac failure in a neonate.

PubMed

Su, Jennifer A; Tang, William; Rivero, Niurka; Bar-Cohen, Yaniv

2014-05-01

A 2-week-old infant with normal intracardiac anatomy presented to the emergency department in a hypertensive crisis with acute cardiac failure. Despite extensive evaluation, no underlying disease was found. The patient's hypertension and cardiac dysfunction resolved after 1 week of supportive care in the PICU, and she was discharged within 2 weeks of presentation. The patient's history revealed transplacental exposure to the α-adrenergic agonist methyldopa for 10 weeks before delivery. Her age at presentation and the self-limited nature of cardiac sequelae with complete resolution of cardiac dysfunction suggest withdrawal effects from this exposure. Whereas the rebound hypertensive effects of α-adrenergic agonists are well established in the adult population, this report shows an unusual adverse outcome of in utero exposure to methyldopa. Copyright © 2014 by the American Academy of Pediatrics.

Ultratrace LC-MS/MS analysis of segmented calf hair for retrospective assessment of time of clenbuterol administration in Agriforensics.

PubMed

Duvivier, Wilco F; van Beek, Teris A; Meijer, Thijs; Peeters, Ruth J P; Groot, Maria J; Sterk, Saskia S; Nielen, Michel W F

2015-01-21

In agriforensics, time of administration is often debated when illegal drug residues, such as clenbuterol, are found in frequently traded cattle. In this proof-of-concept work, the feasibility of obtaining retrospective timeline information from segmented calf tail hair analyses has been studied. First, an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) hair analysis method was adapted to accommodate smaller sample sizes and in-house validated. Then, longitudinal 1 cm segments of calf tail hair were analyzed to obtain clenbuterol concentration profiles. The profiles found were in good agreement with calculated, theoretical positions of the clenbuterol residues along the hair. Following assessment of the average growth rate of calf tail hair, time of clenbuterol administration could be retrospectively determined from segmented hair analysis data. The data from the initial animal treatment study (n = 2) suggest that time of treatment can be retrospectively estimated with an error of 3-17 days.

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.

Sports doping: emerging designer and therapeutic β2-agonists.

PubMed

Fragkaki, A G; Georgakopoulos, C; Sterk, S; Nielen, M W F

2013-10-21

Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future. © 2013.

Modulation of the Cholinergic Mechanisms in the Bronchial Smooth Muscle.

DTIC Science & Technology

1984-06-01

after addition of the muscarinic agonist oxotremorine . Presynaptic Ach receptors were first reported to occur on nor- adrenergic terminals...muscarinic agonist, oxotremorine , reduced the output of [3H,-Ach by only 20% (Paper IV, Figure 4). This is a strong indication for the existence of...presynaptic muscarinic receptors, which modulate the release of Ach. The oxotremorine reduced release of [3H]-Ach upon stimulation was not mediated by a

Anti-Brownian ELectrokinetic (ABEL) trapping of single β2-adrenergic receptors in the absence and presence of agonist

NASA Astrophysics Data System (ADS)

Bockenhauer, Samuel; Fuerstenberg, Alexandre; Yao, Xiao Jie; Kobilka, Brian K.; Moerner, W. E.

2012-02-01

The ABEL trap allows trapping of single biomolecules in solution for extended observation without immobilization. The essential idea combines fluorescence-based position estimation with fast electrokinetic feedback in a microfluidic geometry to counter the Brownian motion of a single nanoscale object, hence maintaining its position in the field of view for hundreds of milliseconds to seconds. Such prolonged observation of single proteins allows access to slow dynamics, as probed by any available photophysical observables. We have used the ABEL trap to study conformational dynamics of the β2-adrenergic receptor, a key G-protein coupled receptor and drug target, in the absence and presence of agonist. A single environment-sensitive dye reports on the receptor microenvironment, providing a real-time readout of conformational change for each trapped receptor. The focus of this paper will be a quantitative comparison of the ligandfree and agonist-bound receptor data from our ABEL trap experiments. We observe a small but clearly detectable shift in conformational equilibria and a lengthening of fluctuation timescales upon binding of agonist. In order to quantify the shift in state distributions and timescales, we apply nonparametric statistical tests to place error bounds on the resulting single-molecule distributions.

Airway reactivity in chronic obstructive pulmonary disease. Failure of in vivo methacholine responsiveness to correlate with cholinergic, adrenergic, or nonadrenergic responses in vitro.

PubMed

Taylor, S M; Paré, P D; Armour, C L; Hogg, J C; Schellenberg, R R

1985-07-01

This study aimed to determine whether in vivo airways hyperreactivity was manifested by either enhanced bronchial smooth muscle responses to contractile stimuli or by deficient responses to relaxant stimuli in vitro. Quantitative responses to nebulized methacholine were obtained in 12 human subjects prior to pulmonary resection. The provocative concentration of methacholine producing a 20% reduction in FEV1 (PC20) was calculated, and these values were compared with in vitro responses of bronchial smooth muscle strips from the surgical specimens. Both contractile cholinergic responses and relaxant nonadrenergic noncholinergic dose-response data were obtained for the in vitro bronchial specimens by electrical field stimulation. In addition, cumulative dose responses were obtained to exogenously added methacholine, the beta-adrenergic agonist salbutamol, and the adenylate cyclase activator forskolin. Despite a wide range of PC20 values, the in vivo airway responsiveness did not correlate with any of the in vitro responses examined, suggesting that airway reactivity is not due solely to the responsiveness of smooth muscle to contractile agonists nor to a localized deficiency in the nonadrenergic inhibitory system, beta-adrenergic inhibition, or abnormal cyclic-AMP-mediated pathways of relaxation.

Beta 2-adrenergic receptor agonists are novel regulators of macrophage activation in diabetic renal and cardiovascular complications.

PubMed

Noh, Hyunjin; Yu, Mi Ra; Kim, Hyun Joo; Lee, Ji Hye; Park, Byoung-Won; Wu, I-Hsien; Matsumoto, Motonobu; King, George L

2017-07-01

Macrophage activation is increased in diabetes and correlated with the onset and progression of vascular complications. To identify drugs that could inhibit macrophage activation, we developed a cell-based assay and screened a 1,040 compound library for anti-inflammatory effects. Beta2-adrenergic receptor (β2AR) agonists were identified as the most potent inhibitors of phorbol myristate acetate-induced tumor necrosis factor-α production in rat bone marrow macrophages. In peripheral blood mononuclear cells isolated from streptozotocin-induced diabetic rats, β2AR agonists inhibited diabetes-induced tumor necrosis factor-α production, which was prevented by co-treatment with a selective β2AR blocker. To clarify the underlying mechanisms, THP-1 cells and bone marrow macrophages were exposed to high glucose. High glucose reduced β-arrestin2, a negative regulator of NF-κB activation, and its interaction with IκBα. This subsequently enhanced phosphorylation of IκBα and activation of NF-κB. The β2AR agonists enhanced β-arrestin2 and its interaction with IκBα, leading to downregulation of NF-κB. A siRNA specific for β-arrestin2 reversed β2AR agonist-mediated inhibition of NF-κB activation and inflammatory cytokine production. Treatment of Zucker diabetic fatty rats with a β2AR agonist for 12 weeks attenuated monocyte activation as well as pro-inflammatory and pro-fibrotic responses in the kidneys and heart. Thus, β2AR agonists might have protective effects against diabetic renal and cardiovascular complications. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

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

PubMed Central

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

2015-01-01

Internalization of G protein-coupled receptors can be triggered by agonists or by other stimuli. The process begins within seconds of cell activation and contributes to receptor desensitization. The Rab GTPase family controls endocytosis, vesicular trafficking, and endosomal fusion. Among their remarkable properties is the differential distribution of its members on the surface of various organelles. In the endocytic pathway, Rab 5 controls traffic from the plasma membrane to early endosomes, whereas Rab 4 and Rab 11 regulate rapid and slow recycling from early endosomes to the plasma membrane, respectively. Moreover, Rab 7 and Rab 9 regulate the traffic from late endosomes to lysosomes and recycling to the trans-Golgi. We explore the possibility that α1B-adrenergic receptor internalization induced by agonists (homologous) and by unrelated stimuli (heterologous) could involve different Rab proteins. This possibility was explored by Fluorescence Resonance Energy Transfer (FRET) using cells coexpressing α1B-adrenergic receptors tagged with the red fluorescent protein, DsRed, and different Rab proteins tagged with the green fluorescent protein. It was observed that when α1B-adrenergic receptors were stimulated with noradrenaline, the receptors interacted with proteins present in early endosomes, such as the early endosomes antigen 1, Rab 5, Rab 4, and Rab 11 but not with late endosome markers, such as Rab 9 and Rab 7. In contrast, sphingosine 1-phosphate stimulation induced rapid and transient α1B-adrenergic receptor interaction of relatively small magnitude with Rab 5 and a more pronounced and sustained one with Rab 9; interaction was also observed with Rab 7. Moreover, the GTPase activity of the Rab proteins appears to be required because no FRET was observed when dominant-negative Rab mutants were employed. These data indicate that α1B-adrenergic receptors are directed to different endocytic vesicles depending on the desensitization type (homologous vs. heterologous). PMID:25799564

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

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.

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.

Nitric oxide synthase and cyclooxygenase modulate β‐adrenergic cutaneous vasodilatation and sweating in young men

PubMed Central

Fujii, Naoto; McNeely, Brendan D.

2016-01-01

Key points β‐Adrenergic receptor agonists such as isoproterenol induce cutaneous vasodilatation and sweating in humans, but the mechanisms underpinning this response remain unresolved.Using intradermal microdialysis, we evaluated the roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) in β‐adrenergic cutaneous vasodilatation and sweating elicited by administration of isoproterenol.We show that while NOS contributes to β‐adrenergic cutaneous vasodilatation, COX restricts cutaneous vasodilatation.We also show that combined inhibition of NOS and COX augments β‐adrenergic sweatingThese new findings advance our basic knowledge regarding the physiological control of cutaneous blood flow and sweating, and provide important and new information to better understand the physiological significance of β‐adrenergic receptors in the skin. Abstract β‐Adrenergic receptor agonists such as isoproterenol can induce cutaneous vasodilatation and sweating in humans, but the mechanisms underpinning this response remain unresolved. We evaluated the hypotheses that (1) nitric oxide synthase (NOS) contributes to β‐adrenergic cutaneous vasodilatation, whereas cyclooxygenase (COX) limits the vasodilatation, and (2) COX contributes to β‐adrenergic sweating. In 10 young males (25 ± 5 years), cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal forearm skin sites infused with (1) lactated Ringer solution (control), (2) 10 mm N ω‐nitro‐l‐arginine (l‐NNA), a non‐specific NOS inhibitor, (3) 10 mm ketorolac, a non‐specific COX inhibitor, or (4) a combination of l‐NNA and ketorolac. All sites were co‐administered with a high dose of isoproterenol (100 μm) for 3 min to maximally induce β‐adrenergic sweating (β‐adrenergic sweating is significantly blunted by subsequent activations). Approximately 60 min after the washout period, three incremental doses of isoproterenol were co‐administered (1, 10 and 100 μm each for 25 min). Increases in CVC induced by the first and second 100 μm isoproterenol were attenuated by l‐NNA alone, and those in response to all doses of isoproterenol were reduced by l‐NNA with co‐infusion of ketorolac (all P ≤ 0.05). Ketorolac alone augmented increases in CVC induced by 10 μm and by the second 100 μm isoproterenol (both P ≤ 0.05). While isoproterenol‐induced sweating was not affected by the separate administration of l‐NNA or ketorolac (all P > 0.05), their combined administration augmented sweating elicited by the first 3 min of 100 μm isoproterenol (P = 0.05). We show that while NOS contributes to β‐adrenergic cutaneous vasodilatation, COX restrains the vasodilatation. Finally, combined inhibition of NOS and COX augments β‐adrenergic sweating. PMID:27779753

Re-evaluating the efficacy of beta-adrenergic agonists and antagonists in long QT-3 syndrome through computational modelling.

PubMed

Ahrens-Nicklas, Rebecca C; Clancy, Colleen E; Christini, David J

2009-06-01

Long QT syndrome (LQTS) is a heterogeneous collection of inherited cardiac ion channelopathies characterized by a prolonged electrocardiogram QT interval and increased risk of sudden cardiac death. Beta-adrenergic blockers are the mainstay of treatment for LQTS. While their efficacy has been demonstrated in LQTS patients harbouring potassium channel mutations, studies of beta-blockers in subtype 3 (LQT3), which is caused by sodium channel mutations, have produced ambiguous results. In this modelling study, we explore the effects of beta-adrenergic drugs on the LQT3 phenotype. In order to investigate the effects of beta-adrenergic activity and to identify sources of ambiguity in earlier studies, we developed a computational model incorporating the effects of beta-agonists and beta-blockers into an LQT3 mutant guinea pig ventricular myocyte model. Beta-activation suppressed two arrhythmogenic phenomena, transmural dispersion of repolarization and early after depolarizations, in a dose-dependent manner. However, the ability of beta-activation to prevent cardiac conduction block was pacing-rate-dependent. Low-dose beta-blockade by propranolol reversed the beneficial effects of beta-activation, while high dose (which has off-target sodium channel effects) decreased arrhythmia susceptibility. These results demonstrate that beta-activation may be protective in LQT3 and help to reconcile seemingly conflicting results from different experimental models. They also highlight the need for well-controlled clinical investigations re-evaluating the use of beta-blockers in LQT3 patients.

High-performance liquid chromatographic determination of the beta2-selective adrenergic agonist fenoterol in human plasma after fluorescence derivatization.

PubMed

Kramer, S; Blaschke, G

2001-02-10

A sensitive high-performance liquid chromatographic method has been developed for the determination of the beta2-selective adrenergic agonist fenoterol in human plasma. To improve the sensitivity of the method, fenoterol was derivatized with N-(chloroformyl)-carbazole prior to HPLC analysis yielding highly fluorescent derivatives. The assay involves protein precipitation with acetonitrile, liquid-liquid-extraction of fenoterol from plasma with isobutanol under alkaline conditions followed by derivatization with N-(chloroformyl)-carbazole. Reversed-phase liquid chromatographic determination of the fenoterol derivative was performed using a column-switching system consisting of a LiChrospher 100 RP 18 and a LiChrospher RP-Select B column with acetonitrile, methanol and water as mobile phase. The limit of quantitation in human plasma was 376 pg fenoterol/ml. The method was successfully applied for the assay of fenoterol in patient plasma.

Functional and physiological effects of treadmill training induced by buspirone, carbidopa, and L-DOPA in clenbuterol-treated paraplegic mice.

PubMed

Ung, Roth-Visal; Rouleau, Pascal; Guertin, Pierre A

2012-05-01

Chronic spinal cord injury may be complicated by weight loss, muscle atrophy, and bone loss. The authors identified a combination pharmacotherapy using buspirone, carbidopa, and L-DOPA (BCD) that elicits bouts of locomotor-like movements in spinal cord-transected (Tx) mice. They then evaluated the effects of 8 weeks of treadmill training in Tx mice that received BCD or BCD + clenbuterol, a monoaminergic agent with anabolic properties, on locomotor function, muscle atrophy, adipose tissue loss, and bone density measures. Induced locomotor movement, adipose tissue, skeletal muscle, and femoral bone properties were compared in unoperated control mice, operated controls (untreated, untrained Tx mice), and 2 groups of treated, trained Tx mice (Tx + BCD, Tx + BCD + clenbuterol) that also received training. BCD- and BCD + clenbuterol-treated mice showed comparable levels of locomotor movements that significantly improved over time. Soleus muscle mass and soleus and extensor digitorum longus cross-sectional area significantly increased in both groups of BCD-treated mice, with greater effects in BCD + clenbuterol-treated animals. Fiber type conversion, adipose tissues, bone mineral density, and content were reduced in all Tx groups compared with unoperated control mice. These findings suggest that locomotor movement and muscle properties can be restored to near-normal levels after several weeks of BCD treatment, regular training, and clenbuterol in completely paraplegic animals.

Rhabdomyolysis Secondary to Clenbuterol Use and Exercise.

PubMed

Grimmer, Nicole M; Gimbar, Renee Petzel; Bursua, Adam; Patel, Meet

2016-02-01

The literature regarding rhabdomyolysis secondary to illicit drug use is sparse. Clenbuterol is a bronchodilator approved for veterinary use, which in high doses can increase protein deposition and lipolysis similarly to anabolic steroids, and is thereby abused for bodybuilding and weight loss effects. Clenbuterol has previously been described in case reports to be cardiotoxic, with patient presentations similar to overdoses of sympathomimetic substances, but reports of rhabdomyolysis are limited to a single case series in horses. We report the first case of rhabdomyolysis secondary to clenbuterol in a human. Our patient used clenbuterol for muscle-building effects in addition to exercise for multiple days prior to presentation. The patient's chief complaint at Emergency Department (ED) presentation was discolored urine. Workup for rhabdomyolysis was initiated, and an initial creatine kinase was measured at 122,933 units/L. Our patient's rhabdomyolysis was successfully treated with supportive therapy, and the patient was eventually discharged to home with no identifiable disability. The patient's kidney function remained at baseline, and no acute kidney injury was experienced secondary to rhabdomyolysis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Patients presenting to the ED may have been unintentionally exposed through cutting of illicit substances or through intentional use in bodybuilding. Clenbuterol has well-described cardiotoxic effects, and we report the additional toxicity of rhabdomyolysis with its use. Copyright © 2016 Elsevier Inc. All rights reserved.

β1-adrenergic regulation of rapid component of delayed rectifier K+ currents in guinea-pig cardiac myocytes.

PubMed

Wang, Sen; Xu, Di; Wu, Ting-Ting; Guo, Yan; Chen, Yan-Hong; Zou, Jian-Gang

2014-05-01

Human ether-à-go-go-related gene (hERG) potassium channels conduct the rapid component of the delayed rectifier potassium current (IKr), which is crucial for repolarization of cardiac action potential. Patients with hERG‑associated long QT syndrome usually develop tachyarrhythmias during physical and/or emotional stress, both known to stimulate adrenergic receptors. The present study aimed to investigate a putative functional link between β1-adrenergic stimulation and IKr in guinea-pig left ventricular myocytes and to analyze how IKr is regulated following activation of the β1-adrenergic signaling pathway. The IKr current was measured using a whole-cell patch-clamp technique. A selective β1-adrenergic receptor agonist, xamoterol, at concentrations of 0.01-100 µM decreased IKr in a concentration-dependent manner. The 10 µM xamoterol-induced inhibition of IKr was attenuated by the protein kinase A (PKA) inhibitor KT5720, the protein kinase C (PKC) inhibitor chelerythrine, and the phospholipase (PLC) inhibitor U73122, indicating involvement of PKA, PKC and PLC in β1-adrenergic inhibition of IKr. The results of the present study indicate an association between IKr and the β1-adrenergic receptor in arrhythmogenesis, involving the activation of PKA, PKC and PLC.

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

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation

PubMed Central

Baker, Candice N.; Gidus, Sarah A.; Price, George F.; Peoples, Jessica N. R.

2014-01-01

As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP to ATP in mitochondria becomes vital. Relatively little, however, is known about the signaling mechanisms regulating the transition from anaerobic to aerobic metabolism that occurs during the embryonic period. The main objective of this study was to test the hypothesis that adrenergic hormones provide critical stimulation of energy metabolism during embryonic/fetal development. We examined ATP and ADP concentrations in mouse embryos lacking adrenergic hormones due to targeted disruption of the essential dopamine β-hydroxylase (Dbh) gene. Embryonic ATP concentrations decreased dramatically, whereas ADP concentrations rose such that the ATP/ADP ratio in the adrenergic-deficient group was nearly 50-fold less than that found in littermate controls by embryonic day 11.5. We also found that cardiac extracellular acidification and oxygen consumption rates were significantly decreased, and mitochondria were significantly larger and more branched in adrenergic-deficient hearts. Notably, however, the mitochondria were intact with well-formed cristae, and there was no significant difference observed in mitochondrial membrane potential. Maternal administration of the adrenergic receptor agonists isoproterenol or l-phenylephrine significantly ameliorated the decreases in ATP observed in Dbh−/− embryos, suggesting that α- and β-adrenergic receptors were effective modulators of ATP concentrations in mouse embryos in vivo. These data demonstrate that adrenergic hormones stimulate cardiac energy metabolism during a critical period of embryonic development. PMID:25516547

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.

On the treatment of the alcoholic organic brain syndrome with an alpha-adrenergic agonist modafinil: double-blind, placebo-controlled clinical, psychometric and neurophysiological studies.

PubMed

Saletu, B; Saletu, M; Grünberger, J; Frey, R; Zatschek, I; Mader, R

1990-01-01

1. In a double-blind study forty abstinent hospitalized male patients with an alcoholic organic brain syndrome (OBS) were treated for 6 weeks with either 200 mg modafinil or placebo. 2. Modafinil (CRL 40476) is a putative central alpha-1 adrenergic agonist. It's pharmacological profile is quite different from that of amphetamine, which can be seen by the lack of peripheral sympathomimetic effects. The vigilance promoting effect of modafinil has been shown previously in pharmaco-EEG and psychometric studies as well as in clinical studies involving treatment of daytime sleepiness in idiopathic hypersomniacs and narcoleptics. 3. The present clinical investigations demonstrated that the spontaneous restitution of the alcoholic OBS was significantly augmented and accelerated by modafinil. 4. Psychometric tests did not show significant intergroup differences. Modafinil- and placebo-treated patients improved continously over the 6-week period. 5. Psychophysiological and autonomous nervous system parameters were affected neither by placebo nor by modafinil. 6. Neurophysiological investigations by means of quantitative pharmaco-EEG showed partly inconsistent findings. However, superimposed dosages of modafinil (on the top of 6 weeks chronic administration) induced a decrease of slow activity and an increase of alpha activity suggesting an improvement of vigilance after the daily drug intake. 7. Considering the beneficial effects of modafinil in abstinent chronic alcoholic patients, it may be said that activation and improvement of adaptive behaviour by an alpha-adrenergic agonist could be regarded as a therapeutic principle in the treatment of the OBS, eventually due to noradrenergic deficits.

Effect of polymorphism of the beta(2)-adrenergic receptor on response to regular use of albuterol in asthma.

PubMed

Israel, E; Drazen, J M; Liggett, S B; Boushey, H A; Cherniack, R M; Chinchilli, V M; Cooper, D M; Fahy, J V; Fish, J E; Ford, J G; Kraft, M; Kunselman, S; Lazarus, S C; Lemanske, R F; Martin, R J; McLean, D E; Peters, S P; Silverman, E K; Sorkness, C A; Szefler, S J; Weiss, S T; Yandava, C N

2001-01-01

Regular use of inhaled beta-adrenergic agonists may have adverse effects in some asthma patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect its regulation; however, results of smaller studies of the effects of such polymorphisms on response to beta-agonist therapy have been inconsistent. We examined the possible effects of polymorphisms at codons 16 (beta(2)-AR-16) and 27 (beta(2)-AR-27) on response to albuterol by genotyping 190 asthmatics who had participated in a trial of regular versus as-needed albuterol use. During the 16-week treatment period, patients homozygous for arginine (Arg/Arg) at beta(2)-AR-16 who used albuterol regularly had a small decline in morning peak expiratory flow (AM PEF). This effect was magnified during a 4-week run-out period, when all patients returned to as-needed albuterol only. By the end of the study, Arg/Arg subjects who had used albuterol regularly had an AM PEF 30.5 +/- 12.1 liters/min lower (p = 0.012) than Arg/Arg patients who had used albuterol as needed only. Subjects homozygous for glycine at beta(2)-AR-16 showed no such decline. Evening PEF also declined in the Arg/Arg regular but not in as-need albuterol users. No significant differences between regular and as-needed treatment were associated with polymorphisms at beta(2)-AR-27. Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment. Copyright 2001 S. Karger AG, Basel

Gene transfer of heterologous G protein-coupled receptors to cardiomyocytes: differential effects on contractility.

PubMed

Laugwitz, K L; Weig, H J; Moretti, A; Hoffmann, E; Ueblacker, P; Pragst, I; Rosport, K; Schömig, A; Ungerer, M

2001-04-13

In heart failure, reduced cardiac contractility is accompanied by blunted cAMP responses to beta-adrenergic stimulation. Parathyroid hormone (PTH)-related peptide and arginine vasopressin are released from the myocardium in response to increased wall stress but do not stimulate contractility or adenylyl cyclase at physiological concentrations. To bypass the defective beta-adrenergic signaling cascade, recombinant P1 PTH/PTH-related peptide receptors (rPTH1-Rs) and V(2) vasopressin receptors (rV(2)-Rs), which are normally not expressed in the myocardium and which are both strongly coupled to adenylyl cyclase, and recombinant beta(2)-adrenergic receptors (rbeta(2)-ARs) were overexpressed in cardiomyocytes by viral gene transfer. The capacity of endogenous hormones to increase contractility via the heterologous, recombinant receptors was compared. Whereas V(2)-Rs are uniquely coupled to Gs, PTH1-Rs and beta(2)-ARs are also coupled to other G proteins. Gene transfer of rPTH1-Rs or rbeta(2)-ARs to adult cardiomyocytes resulted in maximally increased basal contractility, which could not be further stimulated by adding receptor agonists. Agonists at rPTH1-Rs induced increased cAMP formation and phospholipase C activity. In contrast, healthy or failing rV(2)-R-expressing cardiomyocytes showed unaltered basal contractility. Their contractility and cAMP formation increased only at agonist exposure, which did not activate phospholipase C. In summary, we found that gene transfer of PTH1-Rs to cardiomyocytes results in constitutive activity of the transgene, as does that of beta(2)-ARS: In the absence of receptor agonists, rPTH1-Rs and rbeta(2)-ARs increase basal contractility, coupling to 2 G proteins simultaneously. In contrast, rV(2)-Rs are uniquely coupled to Gs and are not constitutively active, retaining their property to be activated exclusively on agonist stimulation. Therefore, gene transfer of V(2)-Rs might be more suited to test the effects of cAMP-stimulating receptors in heart failure than that of PTH1-Rs or beta(2)-ARS:

Preparation of clenbuterol imprinted monolithic polymer with hydrophilic outer layers by reversible addition-fragmentation chain transfer radical polymerization and its application in the clenbuterol determination from human serum by on-line solid-phase extraction/HPLC analysis.

PubMed

Li, Xiaobing; Zhou, Man; Turson, Mamat; Lin, Shen; Jiang, Ping; Dong, Xiangchao

2013-05-21

A novel imprinted monolithic material with the ability of protein exclusion was developed for the selective extraction of clenbuterol (CLE) from biological samples by direct injection in the HPLC analysis. The material has an imprinted inner structure and hydrophilic outer layer. The reversible addition-fragmentation chain transfer (RAFT) polymerization was employed in the material preparation by a two-step procedure. In the first step, clenbuterol imprinted monolithic polymer was synthesized by combining the molecular imprinting and the RAFT polymerization techniques. The resulting monolithic polymer has a RAFT chain transfer agent (trithioester groups) in its structure, which was used to graft poly(glycerol mono-methacrylate) [pGMMA] in the second step by post-RAFT polymerization. The hydrophilic pGMMA layers grafted on the surface of the imprinted monolith created barriers for protein diffusion. More than 90% of bovine serum albumin can be excluded from the pGMMA coated monolithic column. Meanwhile the clenbuterol was retained selectively with a large retention factor. The result indicated that the column, denoted as RA-MIM, has both the merits of a molecularly imprinted polymer and restricted access material. By using RA-MIM as the solid-phase extraction pre-column, an on-line column-switching HPLC method for the determination of clenbuterol in human serum has been established and validated. The recoveries of clenbuterol from the serum were 87.3-96.9% in the spiked level 2-1000 ng mL(-1). Both good linearity (R = 0.999) and acceptable reproducibility (RSD < 7.0%) were obtained. The limit of detection and the limit of quantitation were 0.7 ng mL(-1) and 2.0 ng mL(-1) respectively, which is sensitive in terms of UV detection. The results have demonstrated that the RAFT polymerization can be used to synthesize bi-functional monolithic columns by using its living reaction property. The resulting RA-MIM in this research can be used for efficient clenbuterol determination by HPLC from biological samples.

COMPARISON OF TWO α2-ADRENERGIC AGONISTS ON URINE CONTAMINATION OF SEMEN COLLECTED BY ELECTROEJACULATION IN CAPTIVE AND SEMI-FREE-RANGING CHEETAH (ACINONYX JUBATUS).

PubMed

Marrow, Judilee C; Woc-Colburn, Margarita; Hayek, Lee-Ann C; Marker, Laurie; Murray, Suzan

2015-06-01

Alpha2-adrenergic agonists are used to immobilize many veterinary species, but use has been infrequently linked to urine contamination of semen collected via electroejaculation. The objective of the study was to compare the α2-agonists medetomidine and dexmedetomidine on urine contamination of semen in anesthetized cheetahs (Acinonyx jubatus) during electroejaculation procedures. From 2009-2012, a retrospective medical record review revealed 21 anesthesia events in 12 adult male cheetahs. Animals were immobilized with combinations of Telazol® (2.33±0.43 mg/kg) and ketamine (2.38±1 mg/kg); Telazol (1.17±0.14 mg/kg), ketamine (1.17±0.14 mg/kg), and medetomidine (0.012±0.0017 mg/kg); or Telazol (1.59±0.1 mg/kg), ketamine (1.59±0.1 mg/kg) and dexmedetomidine (0.01±0.001 mg/kg). Semen was successfully collected in all animals; four animals anesthetized with medetomidine had urine contamination (P=0.037). Medetomidine may contribute to urine contamination; however, further investigation is needed to determine significance in cheetahs.

Ventricular action potential adaptation to regular exercise: role of β-adrenergic and KATP channel function.

PubMed

Wang, Xinrui; Fitts, Robert H

2017-08-01

Regular exercise training is known to affect the action potential duration (APD) and improve heart function, but involvement of β-adrenergic receptor (β-AR) subtypes and/or the ATP-sensitive K + (K ATP ) channel is unknown. To address this, female and male Sprague-Dawley rats were randomly assigned to voluntary wheel-running or control groups; they were anesthetized after 6-8 wk of training, and myocytes were isolated. Exercise training significantly increased APD of apex and base myocytes at 1 Hz and decreased APD at 10 Hz. Ca 2+ transient durations reflected the changes in APD, while Ca 2+ transient amplitudes were unaffected by wheel running. The nonselective β-AR agonist isoproterenol shortened the myocyte APD, an effect reduced by wheel running. The isoproterenol-induced shortening of APD was largely reversed by the selective β 1 -AR blocker atenolol, but not the β 2 -AR blocker ICI 118,551, providing evidence that wheel running reduced the sensitivity of the β 1 -AR. At 10 Hz, the K ATP channel inhibitor glibenclamide prolonged the myocyte APD more in exercise-trained than control rats, implicating a role for this channel in the exercise-induced APD shortening at 10 Hz. A novel finding of this work was the dual importance of altered β 1 -AR responsiveness and K ATP channel function in the training-induced regulation of APD. Of physiological importance to the beating heart, the reduced response to adrenergic agonists would enhance cardiac contractility at resting rates, where sympathetic drive is low, by prolonging APD and Ca 2+ influx; during exercise, an increase in K ATP channel activity would shorten APD and, thus, protect the heart against Ca 2+ overload or inadequate filling. NEW & NOTEWORTHY Our data demonstrated that regular exercise prolonged the action potential and Ca 2+ transient durations in myocytes isolated from apex and base regions at 1-Hz and shortened both at 10-Hz stimulation. Novel findings were that wheel running shifted the β-adrenergic receptor agonist dose-response curve rightward compared with controls by reducing β 1 -adrenergic receptor responsiveness and that, at the high activation rate, myocytes from trained animals showed higher K ATP channel function. Copyright © 2017 the American Physiological Society.

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.

Effect of hindlimb suspension and clenbuterol treatment on polyamine levels in skeletal muscle

NASA Technical Reports Server (NTRS)

Abukhalaf, Imad K.; von Deutsch, Daniel A.; Wineski, Lawrence E.; Silvestrov, Natalia A.; Abera, Saare A.; Sahlu, Sinafikish W.; Potter, David E.; Thierry-Palmer, M. (Principal Investigator)

2002-01-01

Polyamines are unbiquitous, naturally occurring small aliphatic, polycationic, endogenous compounds. They are involved in many cellular processes and may serve as secondary or tertiary messengers to hormonal regulation. The relationship of polyamines and skeletal muscle mass of adductor longus, extensor digitorum longus, and gastrocnemius under unloading (hindlimb suspension) conditions was investigated. Unloading significantly affected skeletal muscle polyamine levels in a fiber-type-specific fashion. Under loading conditions, clenbuterol treatment increased all polyamine levels, whereas under unloading conditions, only the spermidine levels were consistently increased. Unloading attenuated the anabolic effects of clenbuterol in predominately slow-twitch muscles (adductor longus), but had little impact on clenbuterol's action as a countermeasure in fast- twitch muscles such as the extensor digitorum longus. Spermidine appeared to be the primary polyamine involved in skeletal muscle atrophy/hypertrophy. Copyright 2002 S. Karger AG, Basel.

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

The actions of isoprenaline and mirabegron in the isolated whole rat and guinea pig bladder.

PubMed

Persyn, Sara; De Wachter, Stefan; Wyndaele, Jean-Jacques; Eastham, Jane; Gillespie, James

2016-07-01

β3-adrenoceptor agonists influence overactive bladder in humans and animal models. However, data is emerging that the mode of action of these drugs is complex. The present study explored the actions of the β3-adrenergic agonist mirabegron and the non-selective agonist isoprenaline on the contractile systems in the rat and guinea pig bladder. Intravesical pressure was measured in isolated whole bladders from female adult animals. In both species spontaneous contractile activity was observed. The muscarinic agonist arecaidine produced complex responses consisting of an initial transient pressure rise followed by complex phasic activity. Three contractile elements were identified: intrinsic micro-contractile activity, initial transient response and steady state phasic activity. The intrinsic and steady state activity could be further divided into a baseline pressure with superimposed phasic activity. The effects of isoprenaline and mirabegron were investigated on these elements. In the rat, the micro-contractile activity could be completely inhibited by isoprenaline (full agonist). The arecaidine-induced initial and steady state baseline pressures were partially reduced, while the phasic activity was little affected. In the guinea pig, both the arecaidine-induced baseline pressure and the phasic activity were affected by isoprenaline. Mirabegron didn't produce significant inhibitory effects in any of the contractile elements in either species. These results show that complex contractile systems operate in the rat and guinea pig bladder that can be modulated by β1/β2-adrenoceptor mechanisms. No evidence was obtained for any β3-dependent regulation of contraction. These data support similar data in humans. Therefore the primary site of therapeutic action of β3-adrenergic agonists remains unknown. Copyright © 2016 Elsevier B.V. All rights reserved.

β2 adrenergic agonist suppresses eosinophil-induced epithelial-to-mesenchymal transition of bronchial epithelial cells.

PubMed

Kainuma, Keigo; Kobayashi, Tetsu; D'Alessandro-Gabazza, Corina N; Toda, Masaaki; Yasuma, Taro; Nishihama, Kota; Fujimoto, Hajime; Kuwabara, Yu; Hosoki, Koa; Nagao, Mizuho; Fujisawa, Takao; Gabazza, Esteban C

2017-05-02

Epithelial-mesenchymal transition is currently recognized as an important mechanism for the increased number of myofibroblasts in cancer and fibrotic diseases. We have already reported that epithelial-mesenchymal transition is involved in airway remodeling induced by eosinophils. Procaterol is a selective and full β 2 adrenergic agonist that is used as a rescue of asthmatic attack inhaler form and orally as a controller. In this study, we evaluated whether procaterol can suppress epithelial-mesenchymal transition of airway epithelial cells induced by eosinophils. Epithelial-mesenchymal transition was assessed using a co-culture system of human bronchial epithelial cells and primary human eosinophils or an eosinophilic leukemia cell line. Procaterol significantly inhibited co-culture associated morphological changes of bronchial epithelial cells, decreased the expression of vimentin, and increased the expression of E-cadherin compared to control. Butoxamine, a specific β 2 -adrenergic antagonist, significantly blocked changes induced by procaterol. In addition, procaterol inhibited the expression of adhesion molecules induced during the interaction between eosinophils and bronchial epithelial cells, suggesting the involvement of adhesion molecules in the process of epithelial-mesenchymal transition. Forskolin, a cyclic adenosine monophosphate-promoting agent, exhibits similar inhibitory activity of procaterol. Overall, these observations support the beneficial effect of procaterol on airway remodeling frequently associated with chronic obstructive pulmonary diseases.

Adrenergic support in septic shock: a critical review.

PubMed

Póvoa, Pedro; Carneiro, António H

2010-02-01

The definition of septic shock includes sepsis-induced hypotension despite adequate fluid resuscitation, along with the presence of organ perfusion abnormalities, and ultimately cell dysfunction. To restore adequate organ perfusion and cell homeostasis, cardiac output should be restored with volume infusion plus vasopressor agents as indicated. Appropriate arterial pressure for each individual patient and proper arterial oxygen content are key elements to restoring perfusion. Tissue perfusion can be monitored by markers of organ and mitochondrial function, namely urine output, level of consciousness, peripheral skin perfusion, central or mixed venous oxygen saturation, and lactate. The hemodynamic effects of the different vasopressor agents depend on the relative affinity to adrenergic receptors. Those with predominant alpha-agonist activity produce more vasoconstriction (inoconstrictors) while those with predominant beta-agonist stimulation increase cardiac performance (inodilators). The debate about whether one vasopressor agent is superior to another is still ongoing. The Surviving Sepsis Campaign guidelines refer to either norepinephrine or dopamine as the first-choice vasopressor agent to correct hypotension in septic shock. However, recent data from observational and controlled trials have challenged these recommendations concerning different adrenergic agents. As a result, our view on the prescription of vasopressors has changed from a probably oversimplified "one-size-fits-all" approach to a multimodal approach in vasopressor selection.

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)

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

Acute exposure of primary rat soleus muscle to zilpaterol HCl (β2 adrenergic agonist), TNFα, or IL-6 in culture increases glucose oxidation rates independent of the impact on insulin signaling or glucose uptake.

PubMed

Cadaret, Caitlin N; Beede, Kristin A; Riley, Hannah E; Yates, Dustin T

2017-08-01

Recent studies show that adrenergic agonists and inflammatory cytokines can stimulate skeletal muscle glucose uptake, but it is unclear if glucose oxidation is similarly increased. Thus, the objective of this study was to determine the effects of ractopamine HCl (β1 agonist), zilpaterol HCl (β2 agonist), TNFα, and IL-6 on glucose uptake and oxidation rates in unstimulated and insulin-stimulated soleus muscle strips from adult Sprague-Dawley rats. Effects on phosphorylation of Akt (phospho-Akt), p38 MAPK (phospho-p38), and p44/42 MAPK (phospho-p44/42) was also determined. Incubation with insulin increased (P<0.05) glucose uptake by ∼47%, glucose oxidation by ∼32%, and phospho-Akt by ∼238%. Insulin also increased (P<0.05) phospho-p38, but only after 2h in incubation. Muscle incubated with β2 agonist alone exhibited ∼20% less (P<0.05) glucose uptake but ∼32% greater (P<0.05) glucose oxidation than unstimulated muscle. Moreover, co-incubation with insulin+β2 agonist increased (P<0.05) glucose oxidation and phospho-Akt compared to insulin alone. Conversely, β1 agonist did not appear to affect basal or insulin-stimulated glucose metabolism, and neither β agonist affected phospho-p44/42. TNFα and IL-6 increased (P<0.05) glucose oxidation by ∼23% and ∼33%, respectively, in the absence of insulin. This coincided with increased (P<0.05) phospho-p38 and phospho-p44/42 but not phospho-Akt. Furthermore, co-incubation of muscle with insulin+either cytokine yielded glucose oxidation rates that were similar to insulin alone, despite lower (P<0.05) phospho-Akt. Importantly, cytokine-mediated increases in glucose oxidation rates were not concomitant with greater glucose uptake. These results show that acute β2 adrenergic stimulation, but not β1 stimulation, directly increases fractional glucose oxidation in the absence of insulin and synergistically increases glucose oxidation when combined with insulin. The cytokines, TNFα and IL-6, likewise directly increased glucose oxidation in the absence of insulin, but were not additive in combination with insulin and in fact appeared to disrupt Akt-mediated insulin signaling. Rather, cytokines appear to be acting through MAPKs to elicit effects on glucose oxidation. Regardless, stimulation of glucose oxidation by these key stress factors did not rely upon greater glucose uptake, which may promote metabolic efficiency during acute stress by increasing fractional glucose oxidation without increasing total glucose consumption by muscle. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation.

PubMed

Baker, Candice N; Gidus, Sarah A; Price, George F; Peoples, Jessica N R; Ebert, Steven N

2015-03-01

As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP to ATP in mitochondria becomes vital. Relatively little, however, is known about the signaling mechanisms regulating the transition from anaerobic to aerobic metabolism that occurs during the embryonic period. The main objective of this study was to test the hypothesis that adrenergic hormones provide critical stimulation of energy metabolism during embryonic/fetal development. We examined ATP and ADP concentrations in mouse embryos lacking adrenergic hormones due to targeted disruption of the essential dopamine β-hydroxylase (Dbh) gene. Embryonic ATP concentrations decreased dramatically, whereas ADP concentrations rose such that the ATP/ADP ratio in the adrenergic-deficient group was nearly 50-fold less than that found in littermate controls by embryonic day 11.5. We also found that cardiac extracellular acidification and oxygen consumption rates were significantly decreased, and mitochondria were significantly larger and more branched in adrenergic-deficient hearts. Notably, however, the mitochondria were intact with well-formed cristae, and there was no significant difference observed in mitochondrial membrane potential. Maternal administration of the adrenergic receptor agonists isoproterenol or l-phenylephrine significantly ameliorated the decreases in ATP observed in Dbh-/- embryos, suggesting that α- and β-adrenergic receptors were effective modulators of ATP concentrations in mouse embryos in vivo. These data demonstrate that adrenergic hormones stimulate cardiac energy metabolism during a critical period of embryonic development. Copyright © 2015 the American Physiological Society.

The contributions of cardiac myosin binding protein C and troponin I phosphorylation to β‐adrenergic enhancement of in vivo cardiac function

PubMed Central

Gresham, Kenneth S.

2016-01-01

Key points β‐adrenergic stimulation increases cardiac myosin binding protein C (MyBP‐C) and troponin I phosphorylation to accelerate pressure development and relaxation in vivo, although their relative contributions remain unknown.Using a novel mouse model lacking protein kinase A‐phosphorylatable troponin I (TnI) and MyBP‐C, we examined in vivo haemodynamic function before and after infusion of the β‐agonist dobutamine.Mice expressing phospho‐ablated MyBP‐C displayed cardiac hypertrophy and prevented full acceleration of pressure development and relaxation in response to dobutamine, whereas expression of phosphor‐ablated TnI alone had little effect on the acceleration of contractile function in response to dobutamine.Our data demonstrate that MyBP‐C phosphorylation is the principal mediator of the contractile response to increased β‐agonist stimulation in vivo.These results help us understand why MyBP‐C dephosphorylation in the failing heart contributes to contractile dysfunction and decreased adrenergic reserve in response to acute stress. Abstract β‐adrenergic stimulation plays a critical role in accelerating ventricular contraction and speeding relaxation to match cardiac output to changing circulatory demands. Two key myofilaments proteins, troponin I (TnI) and myosin binding protein‐C (MyBP‐C), are phosphorylated following β‐adrenergic stimulation; however, their relative contributions to the enhancement of in vivo cardiac contractility are unknown. To examine the roles of TnI and MyBP‐C phosphorylation in β‐adrenergic‐mediated enhancement of cardiac function, transgenic (TG) mice expressing non‐phosphorylatable TnI protein kinase A (PKA) residues (i.e. serine to alanine substitution at Ser23/24; TnIPKA−) were bred with mice expressing non‐phosphorylatable MyBP‐C PKA residues (i.e. serine to alanine substitution at Ser273, Ser282 and Ser302; MyBPCPKA−) to generate a novel mouse model expressing non‐phosphorylatable PKA residues in TnI and MyBP‐C (DBLPKA−). MyBP‐C dephosphorylation produced cardiac hypertrophy and increased wall thickness in MyBPCPKA− and DBLPKA− mice, and in vivo echocardiography and pressure–volume catheterization studies revealed impaired systolic function and prolonged diastolic relaxation compared to wild‐type and TnIPKA– mice. Infusion of the β‐agonist dobutamine resulted in accelerated rates of pressure development and relaxation in all mice; however, MyBPCPKA− and DBLPKA− mice displayed a blunted contractile response compared to wild‐type and TnIPKA– mice. Furthermore, unanaesthesized MyBPCPKA− and DBLPKA− mice displayed depressed maximum systolic pressure in response to dobutamine as measured using implantable telemetry devices. Taken together, our data show that MyBP‐C phosphorylation is a critical modulator of the in vivo acceleration of pressure development and relaxation as a result of enhanced β‐adrenergic stimulation, and reduced MyBP‐C phosphorylation may underlie depressed adrenergic reserve in heart failure. PMID:26635197

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

Transdermal nitroglycerin for the treatment of preterm labor: a systematic review and metaanalysis.

PubMed

Conde-Agudelo, Agustín; Romero, Roberto

2013-12-01

The purpose of this study was to evaluate the efficacy and safety of transdermal nitroglycerin as a tocolytic agent in women with preterm labor. We conducted a systematic review and metaanalysis of randomized controlled trials. Thirteen studies were included (1302 women) comparing transdermal nitroglycerin vs placebo (2 studies; n = 186); β2-adrenergic receptor agonists (9 studies; n = 1024); nifedipine (1 study; n = 50); and magnesium sulfate (1 study; n = 42). There were no significant differences between transdermal nitroglycerin and placebo for delivery within 48 hours of the initiation of treatment or at <28, <34, or <37 weeks of gestation, adverse neonatal outcomes, and neurodevelopmental status at 24 months of life. Nevertheless, 1 study found a marginally significant reduction in the risk of a composite outcome of major neonatal morbidity and perinatal death (3/74 [4.1%] vs 11/79 [13.9%]; relative risk, 0.29; 95% confidence interval, 0.08-1.00). When compared with β2-adrenergic receptor agonists, transdermal nitroglycerin was associated with a significant reduction in the risk of preterm birth at <34 and <37 weeks of gestation, admission to the neonatal intensive care unit, use of mechanical ventilation, and maternal side effects. There were no significant differences between transdermal nitroglycerin and nifedipine and magnesium sulfate in delivery within 48 hours of treatment and pregnancy prolongation, respectively. Overall, women who received transdermal nitroglycerin had a higher risk of headache. Although transdermal nitroglycerin appears to be more effective than β2-adrenergic receptor agonists, the current evidence does not support its routine use as a tocolytic agent for the treatment of preterm labor. Further double-blind placebo-controlled trials are needed. Copyright © 2013 Mosby, Inc. All rights reserved.

TRANSDERMAL NITROGLYCERIN FOR THE TREATMENT OF PRETERM LABOR: A SYSTEMATIC REVIEW AND META-ANALYSIS

PubMed Central

CONDE-AGUDELO, Agustín; ROMERO, Roberto

2014-01-01

OBJECTIVE To evaluate the efficacy and safety of transdermal nitroglycerin as tocolytic agent in women with preterm labor. STUDY DESIGN Systematic review and meta-analysis of randomized controlled trials. RESULTS Thirteen studies (1302 women) were included. Two studies evaluated transdermal nitroglycerin versus placebo (N=186), 9 evaluated transdermal nitroglycerin versus β2-adrenergic-receptor agonists (N=1024), and 1 each evaluated transdermal nitroglycerin versus nifedipine (N=50) and transdermal nitroglycerin versus magnesium sulfate (N=42). There were no significant differences between transdermal nitroglycerin and placebo for delivery within 48 hours of initiation of treatment or before 28, 34 or 37 weeks’ gestation, adverse neonatal outcomes, and neurodevelopmental status at 24 months of age. Nevertheless, one study found a marginally significant reduction in the risk of a composite outcome of significant neonatal morbidity and perinatal mortality (3/74 [4.1%] versus 11/79 [13.9%]; relative risk 0.29, 95% confidence interval 0.08–1.00). When compared with β2-adrenergic-receptor agonists, transdermal nitroglycerin was associated with a significant reduction in the risk of preterm birth <34 and <37 weeks’ gestation, admission to the neonatal intensive care unit, use of mechanical ventilation, and maternal side effects. There were no significant differences between transdermal nitroglycerin and nifedipine and magnesium sulfate in delivery within 48 hours of treatment and pregnancy prolongation, respectively. Overall, women receiving transdermal nitroglycerin had a higher risk of headache. CONCLUSION Although transdermal nitroglycerin appears to be more effective than β 2-adrenergic-receptor agonists, the current evidence does not support its routine use as tocolytic agent for the treatment of preterm labor. Further additional double-blind placebo-controlled trials are needed. PMID:23891631

Modulation of neuroinflammation and pathology in the 5XFAD mouse model of Alzheimer's disease using a biased and selective beta-1 adrenergic receptor partial agonist.

PubMed

Ardestani, Pooneh Memar; Evans, Andrew K; Yi, Bitna; Nguyen, Tiffany; Coutellier, Laurence; Shamloo, Mehrdad

2017-04-01

Degeneration of noradrenergic neurons occurs at an early stage of Alzheimer's Disease (AD). The noradrenergic system regulates arousal and learning and memory, and has been implicated in regulating neuroinflammation. Loss of noradrenergic tone may underlie AD progression at many levels. We have previously shown that acute administration of a partial agonist of the beta-1 adrenergic receptor (ADRB1), xamoterol, restores behavioral deficits in a mouse model of AD. The current studies examined the effects of chronic low dose xamoterol on neuroinflammation, pathology, and behavior in the pathologically aggressive 5XFAD transgenic mouse model of AD. In vitro experiments in cells expressing human beta adrenergic receptors demonstrate that xamoterol is highly selective for ADRB1 and functionally biased for the cAMP over the β-arrestin pathway. Data demonstrate ADRB1-mediated attenuation of TNF-α production with xamoterol in primary rat microglia culture following LPS challenge. Finally, two independent cohorts of 5XFAD and control mice were administered xamoterol from approximately 4.0-6.5 or 7.0-9.5 months, were tested in an array of behavioral tasks, and brains were examined for evidence of neuroinflammation, and amyloid beta and tau pathology. Xamoterol reduced mRNA expression of neuroinflammatory markers (Iba1, CD74, CD14 and TGFβ) and immunohistochemical evidence for microgliosis and astrogliosis. Xamoterol reduced amyloid beta and tau pathology as measured by regional immunohistochemistry. Behavioral deficits were not observed for 5XFAD mice. In conclusion, chronic administration of a selective, functionally biased, partial agonist of ADRB1 is effective in reducing neuroinflammation and amyloid beta and tau pathology in the 5XFAD model of AD. Copyright © 2017 Elsevier Ltd. All rights reserved.

Src family kinases mediate the inhibition of substance P release in the rat spinal cord by μ-opioid receptors and GABAB receptors, but not α2 adrenergic receptors

PubMed Central

Zhang, Guohua; Chen, Wenling; Marvizón, Juan Carlos G.

2010-01-01

GABAB, μ-opioid, and adrenergic α2 receptors inhibit substance P release from primary afferent terminals in the dorsal horn. Studies in cell expression systems suggest that μ-opioid and GABAB receptors inhibit transmitter release from primary afferents by activating Src family kinases (SFKs), which then phosphorylate and inhibit voltage-gated calcium channels. This study investigated whether SFKs mediate the inhibition of substance P release by these three receptors. Substance P release was measured as neurokinin 1 receptor (NK1R) internalization in spinal cord slices and in vivo. In slices, NK1R internalization induced by high frequency dorsal root stimulation was inhibited by the μ-opioid agonist DAMGO and the GABAB agonist baclofen. This inhibition was reversed by the SFK inhibitor PP1. NK1R internalization induced by low frequency stimulation was also inhibited by DAMGO, but PP1 did not reverse this effect. In vivo, NK1R internalization induced by noxious mechanical stimulation of the hind paw was inhibited by intrathecal DAMGO and baclofen. This inhibition was reversed by intrathecal PP1, but not by the inactive PP1 analog PP3. PP1 produced no effect by itself. The α2 adrenergic agonists medetomidine and guanfacine produced a small but statistically significant inhibition of NK1R internalization induced by low frequency dorsal root stimulation. PP1 did not reverse the inhibition by guanfacine. These results show that SFKs mediate the inhibition of substance P release by μ-opioid and GABAB receptors, but not by α2 receptors, which is probably mediated by the binding of G protein βγ subunits to calcium channels. PMID:20726886

Sex Differences in β-Adrenergic Responsiveness of Action Potentials and Intracellular Calcium Handling in Isolated Rabbit Hearts

PubMed Central

Hoeker, Gregory S.; Hood, Ashleigh R.; Katra, Rodolphe P.; Poelzing, Steven; Pogwizd, Steven M.

2014-01-01

Cardioprotection in females, as observed in the setting of heart failure, has been attributed to sex differences in intracellular calcium handling and its modulation by β-adrenergic signaling. However, further studies examining sex differences in β-adrenergic responsiveness have yielded inconsistent results and have mostly been limited to studies of contractility, ion channel function, or calcium handling alone. Given the close interaction of the action potential (AP) and intracellular calcium transient (CaT) through the process of excitation-contraction coupling, the need for studies exploring the relationship between agonist-induced AP and calcium handling changes in female and male hearts is evident. Thus, the aim of this study was to use optical mapping to examine sex differences in ventricular APs and CaTs measured simultaneously from Langendorff-perfused hearts isolated from naïve adult rabbits during β-adrenergic stimulation. The non-selective β-agonist isoproterenol (Iso) decreased AP duration (APD90), CaT duration (CaD80), and the decay constant of the CaT (τ) in a dose-dependent manner (1–316.2 nM), with a plateau at doses ≥31.6 nM. The Iso-induced changes in APD90 and τ (but not CaD80) were significantly smaller in female than male hearts. These sex differences were more significant at faster (5.5 Hz) than resting rates (3 Hz). Treatment with Iso led to the development of spontaneous calcium release (SCR) with a dose threshold of 31.6 nM. While SCR occurrence was similar in female (49%) and male (53%) hearts, the associated ectopic beats had a lower frequency of occurrence (16% versus 40%) and higher threshold (100 nM versus 31.6 nM) in female than male hearts (p<0.05). In conclusion, female hearts had a decreased capacity to respond to β-adrenergic stimulation, particularly under conditions of increased demand (i.e. faster pacing rates and “maximal” levels of Iso effects), however this reduced β-adrenergic responsiveness of female hearts was associated with reduced arrhythmic activity. PMID:25340795

Progenitor cells are mobilized by acute psychological stress but not beta-adrenergic receptor agonist infusion

PubMed Central

Riddell, Natalie E.; Burns, Victoria E.; Wallace, Graham R.; Edwards, Kate M.; Drayson, Mark; Redwine, Laura S.; Hong, Suzi; Bui, Jack D.; Fischer, Johannes C.; Mills, Paul J.; Bosch, Jos A.

2015-01-01

Objectives Stimuli that activate the sympathetic nervous system, such as acute psychological stress, rapidly invoke a robust mobilization of lymphocytes into the circulation. Experimental animal studies suggest that bone marrow-derived progenitor cells (PCs) also mobilize in response to sympathetic stimulation. Here we tested the effects of acute psychological stress and brief pharmacological β-adrenergic (βAR) stimulation on peripheral PC numbers in humans. Methods In two studies, we investigated PC mobilization in response to an acute speech task (n=26) and βAR-agonist (isoproterenol) infusion (n=20). A subset of 8 participants also underwent the infusion protocol with concomitant administration of the βAR-antagonist propranolol. Flow cytometry was used to enumerate lymphocyte subsets, total progenitor cells, total haematopoietic stem cells (HSC), early HSC (multi-lineage potential), late HSC (lineage committed), and endothelial PCs (EPCs). Results Both psychological stress and βAR-agonist infusion caused the expected mobilization of total monocytes and lymphocytes and CD8+ T lymphocytes. Psychological stress also induced a modest, but significant, increase in total PCs, HSCs, and EPC numbers in peripheral blood. However, infusion of a βAR-agonist did not result in a significant change in circulating PCs. Conclusion PCs are rapidly mobilized by psychological stress via mechanisms independent of βAR-stimulation, although the findings do not exclude βAR-stimulation as a possible cofactor. Considering the clinical and physiological relevance, further research into the mechanisms involved in stress-induced PC mobilization seems warranted. PMID:25747743

Progenitor cells are mobilized by acute psychological stress but not beta-adrenergic receptor agonist infusion.

PubMed

Riddell, Natalie E; Burns, Victoria E; Wallace, Graham R; Edwards, Kate M; Drayson, Mark; Redwine, Laura S; Hong, Suzi; Bui, Jack C; Fischer, Johannes C; Mills, Paul J; Bosch, Jos A

2015-10-01

Stimuli that activate the sympathetic nervous system, such as acute psychological stress, rapidly invoke a robust mobilization of lymphocytes into the circulation. Experimental animal studies suggest that bone marrow-derived progenitor cells (PCs) also mobilize in response to sympathetic stimulation. Here we tested the effects of acute psychological stress and brief pharmacological β-adrenergic (βAR) stimulation on peripheral PC numbers in humans. In two studies, we investigated PC mobilization in response to an acute speech task (n=26) and βAR-agonist (isoproterenol) infusion (n=20). A subset of 8 participants also underwent the infusion protocol with concomitant administration of the βAR-antagonist propranolol. Flow cytometry was used to enumerate lymphocyte subsets, total progenitor cells, total haematopoietic stem cells (HSC), early HSC (multi-lineage potential), late HSC (lineage committed), and endothelial PCs (EPCs). Both psychological stress and βAR-agonist infusion caused the expected mobilization of total monocytes and lymphocytes and CD8(+) T lymphocytes. Psychological stress also induced a modest, but significant, increase in total PCs, HSCs, and EPC numbers in peripheral blood. However, infusion of a βAR-agonist did not result in a significant change in circulating PCs. PCs are rapidly mobilized by psychological stress via mechanisms independent of βAR-stimulation, although the findings do not exclude βAR-stimulation as a possible cofactor. Considering the clinical and physiological relevance, further research into the mechanisms involved in stress-induced PC mobilization seems warranted. Copyright © 2015 Elsevier Inc. All rights reserved.

Differential manipulation of arrestin-3 binding to basal and agonist-activated G protein-coupled receptors.

PubMed

Prokop, Susanne; Perry, Nicole A; Vishnivetskiy, Sergey A; Toth, Andras D; Inoue, Asuka; Milligan, Graeme; Iverson, Tina M; Hunyady, Laszlo; Gurevich, Vsevolod V

2017-08-01

Non-visual arrestins interact with hundreds of different G protein-coupled receptors (GPCRs). Here we show that by introducing mutations into elements that directly bind receptors, the specificity of arrestin-3 can be altered. Several mutations in the two parts of the central "crest" of the arrestin molecule, middle-loop and C-loop, enhanced or reduced arrestin-3 interactions with several GPCRs in receptor subtype and functional state-specific manner. For example, the Lys139Ile substitution in the middle-loop dramatically enhanced the binding to inactive M 2 muscarinic receptor, so that agonist activation of the M 2 did not further increase arrestin-3 binding. Thus, the Lys139Ile mutation made arrestin-3 essentially an activation-independent binding partner of M 2 , whereas its interactions with other receptors, including the β 2 -adrenergic receptor and the D 1 and D 2 dopamine receptors, retained normal activation dependence. In contrast, the Ala248Val mutation enhanced agonist-induced arrestin-3 binding to the β 2 -adrenergic and D 2 dopamine receptors, while reducing its interaction with the D 1 dopamine receptor. These mutations represent the first example of altering arrestin specificity via enhancement of the arrestin-receptor interactions rather than selective reduction of the binding to certain subtypes. Copyright © 2017. Published by Elsevier Inc.

Maternal high-fat diet modulates brown adipose tissue response to B-adrenergic agonist

USDA-ARS?s Scientific Manuscript database

Maternal obesity increases offspring risk for several metabolic diseases. We previously showed that offspring of obese dams are predisposed to obesity, liver and adipose tissue anomalies. However, the effect of maternal obesity on developmental programing brown adipose tissue (BAT) is poorly underst...

Central alpha/sub 2/ adrenergic receptors in the rat cerebral cortex: repopulation kinetics and receptor reserve

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

Adler, C.H.

1986-01-01

The alpha/sub 2/ adrenergic receptor subtype is thought to play a role in the mechanism of action of antidepressant and antihypertensive drugs. This thesis has attempted to shed light on the regulation of central alpha/sub 2/ adrenergic receptors in the rat cerebral cortex. Repopulation kinetics analysis allows for the determination of the rate of receptor production, rate constant of degradation, and half-life of the receptor. This analysis was carried out using both radioligand binding and functional receptor assays at various times following the irreversible inactivation of central alpha/sub 2/ adrenergic receptors by in vivo administration of N-ethoxycarbonyl-2-ethyoxy-1,2-dihydroquinoline (EEDQ). Both alpha/submore » 2/ agonist and antagonist ligand binding sites recovered with a t/sub 1/2/ equal to approximately 4 days. The function of alpha/sub 2/ adrenergic autoreceptors, which inhibit stimulation-evoked release of /sup 3/H-norepinephrine (/sup 3/H-NE) and alpha/sub 2/ adrenergic heteroreceptors which inhibit stimulation-evoked release of /sup 3/H-serotonin (/sup 3/H-5-HT) were assayed. The t/sub 1/2/ for recovery of maximal autoreceptor and heteroreceptor function was 2.4 days and 4.6 days, respectively. The demonstration of a receptor reserve is critical to the interpretation of past and future studies of the alpha/sub 2/ adrenergic receptor since it demonstrates that: (1) alterations in the number of alpha/sub 2/ adrenergic receptor binding sites cannot be extrapolated to the actual function of the alpha/sub 2/ adrenergic receptor; and (2) alterations in the number of alpha/sub 2/ receptors is not necessarily accompanied by a change in the maximum function being studied, but may only result in shifting of the dose-response curve.« less

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

Interleukin 1 and Tumor Necrosis Factor Inhibit Cardiac Myocyte β -adrenergic Responsiveness

NASA Astrophysics Data System (ADS)

Gulick, Tod; Chung, Mina K.; Pieper, Stephen J.; Lange, Louis G.; Schreiner, George F.

1989-09-01

Reversible congestive heart failure can accompany cardiac allograft rejection and inflammatory myocarditis, conditions associated with an immune cell infiltrate of the myocardium. To determine whether immune cell secretory products alter cardiac muscle metabolism without cytotoxicity, we cultured cardiac myocytes in the presence of culture supernatants from activated immune cells. We observed that these culture supernatants inhibit β -adrenergic agonist-mediated increases in cultured cardiac myocyte contractility and intracellular cAMP accumulation. The myocyte contractile response to increased extracellular Ca2+ concentration is unaltered by prior exposure to these culture supernatants, as is the increase in myocyte intracellular cAMP concentration in response to stimulation with forskolin, a direct adenyl cyclase activator. Inhibition occurs in the absence of alteration in β -adrenergic receptor density or ligand binding affinity. Suppressive activity is attributable to the macrophage-derived cytokines interleukin 1 and tumor necrosis factor. Thus, these observations describe a role for defined cytokines in regulating the hormonal responsiveness and function of contractile cells. The effects of interleukin 1 and tumor necrosis factor on intracellular cAMP accumulation may be a model for immune modulation of other cellular functions dependent upon cyclic nucleotide metabolism. The uncoupling of agonist-occupied receptors from adenyl cyclase suggests that β -receptor or guanine nucleotide binding protein function is altered by the direct or indirect action of cytokines on cardiac muscle cells.

Effects of alpha-2 agonists on renal function in hypertensive humans.

PubMed

Goldberg, M; Gehr, M

1985-01-01

Centrally acting adrenergic agonists, by decreasing peripheral adrenergic activity, are effective antihypertensive agents. The older agents, however, especially methyldopa, have been associated with weight gain, clinical edema, and antihypertensive tolerance when used as monotherapy. While acute studies in humans have demonstrated weight gain and sodium retention with clonidine and guanabenz, chronic administration results in a decrease in weight and plasma volume. The absence of chronic weight gain and of sodium retention could be the result of a counterbalance between hypotension-related antinatriuresis, secondary to a decrease in glomerular filtration rate and renal blood flow, and natriuretic activity, as a result of a decrease in renal sympathetic tone. Whereas natriuresis and water diuresis have been demonstrated in animals with acute clonidine or guanabenz administration, this has not been demonstrated in humans. Recent studies in which saline administration was used to precondition humans to a subsequent natriuretic stimulus (i.e., guanabenz-induced decreased renal adrenergic activity) resulted in stabilization of renal blood flow and natriuresis. Selective reduction renal sympathetic activity affecting salt and water transport may explain why guanabenz and probably also clonidine seem to be devoid of the sodium/fluid-retaining properties that are common with other antihypertensive agents. Because agents of this class have effects other than pure central alpha-2 agonism (such as alpha-1 activity), they might have confounding and counterbalancing side effects leading to sodium and water retention.

Comparative molecular field analysis of fenoterol derivatives interacting with an agonist-stabilized form of the β₂-adrenergic receptor.

PubMed

Plazinska, Anita; Pajak, Karolina; Rutkowska, Ewelina; Jimenez, Lucita; Kozocas, Joseph; Koolpe, Gary; Tanga, Mary; Toll, Lawrence; Wainer, Irving W; Jozwiak, Krzysztof

2014-01-01

The β₂-adrenergic receptor (β₂-AR) agonist [(3)H]-(R,R')-methoxyfenoterol was employed as the marker ligand in displacement studies measuring the binding affinities (Ki values) of the stereoisomers of a series of 4'-methoxyfenoterol analogs in which the length of the alkyl substituent at α' position was varied from 0 to 3 carbon atoms. The binding affinities of the compounds were additionally determined using the inverse agonist [(3)H]-CGP-12177 as the marker ligand and the ability of the compounds to stimulate cAMP accumulation, measured as EC₅₀ values, were determined in HEK293 cells expressing the β₂-AR. The data indicate that the highest binding affinities and functional activities were produced by methyl and ethyl substituents at the α' position. The results also indicate that the Ki values obtained using [(3)H]-(R,R')-methoxyfenoterol as the marker ligand modeled the EC₅₀ values obtained from cAMP stimulation better than the data obtained using [(3)H]-CGP-12177 as the marker ligand. The data from this study was combined with data from previous studies and processed using the Comparative Molecular Field Analysis approach to produce a CoMFA model reflecting the binding to the β₂-AR conformation probed by [(3)H]-(R,R')-4'-methoxyfenoterol. The CoMFA model of the agonist-stabilized β₂-AR suggests that the binding of the fenoterol analogs to an agonist-stabilized conformation of the β₂-AR is governed to a greater extend by steric effects than binding to the [(3)H]-CGP-12177-stabilized conformation(s) in which electrostatic interactions play a more predominate role. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparative Molecular Field Analysis of fenoterol derivatives interacting with an agonist-stabilized form of the β2-adrenergic receptor

PubMed Central

Plazinska, Anita; Pajak, Karolina; Rutkowska, Ewelina; Jimenez, Lucita; Kozocas, Joseph; Koolpe, Gary; Tanga, Mary; Toll, Lawrence; Wainer, Irving W.; Jozwiak, Krzysztof

2014-01-01

The β2-adrenergic receptor (β2-AR) agonist [3H]-(R,R′)-methoxyfenoterol was employed as the marker ligand in displacement studies measuring the binding affinities (Ki values) of the stereoisomers of a series of 4′-methoxyfenoterol analogs in which the length of the alkyl substituent at α′ position was varied from 0 to 3 carbon atoms. The binding affinities of the compounds were additionally determined using the inverse agonist [3H]-CGP-12177 as the marker ligand and the ability of the compounds to stimulate cAMP accumulation, measured as EC50 values, were determined in HEK293 cells expressing the β2-AR. The data indicate that the highest binding affinities and functional activities were produced by methyl and ethyl substituents at the α′ position. The results also indicate that the Ki values obtained using [3H]-(R,R′)-methoxyfenoterol as the marker ligand modeled the EC50 values obtained from cAMP stimulation better than the data obtained using [3H]-CGP-12177 as the marker ligand. The data from this study was combined with data from previous studies and processed using the Comparative Molecular Field Analysis approach to produce a CoMFA model reflecting the binding to the β2-AR conformation probed by [3H]-(R,R′)-4′-methoxyfenoterol. The CoMFA model of the agonist-stabilized β2-AR suggests that the binding of the fenoterol analogs to an agonist-stabilized conformation of the β2-AR is governed to a greater extend by steric effects than binding to the [3H]-CGP-12177-stabilized conformation(s) in which electrostatic interactions play a more predominate role. PMID:24326276

Search for β2 Adrenergic Receptor Ligands by Virtual Screening via Grid Computing and Investigation of Binding Modes by Docking and Molecular Dynamics Simulations

PubMed Central

Bai, Qifeng; Shao, Yonghua; Pan, Dabo; Zhang, Yang; Liu, Huanxiang; Yao, Xiaojun

2014-01-01

We designed a program called MolGridCal that can be used to screen small molecule database in grid computing on basis of JPPF grid environment. Based on MolGridCal program, we proposed an integrated strategy for virtual screening and binding mode investigation by combining molecular docking, molecular dynamics (MD) simulations and free energy calculations. To test the effectiveness of MolGridCal, we screened potential ligands for β2 adrenergic receptor (β2AR) from a database containing 50,000 small molecules. MolGridCal can not only send tasks to the grid server automatically, but also can distribute tasks using the screensaver function. As for the results of virtual screening, the known agonist BI-167107 of β2AR is ranked among the top 2% of the screened candidates, indicating MolGridCal program can give reasonable results. To further study the binding mode and refine the results of MolGridCal, more accurate docking and scoring methods are used to estimate the binding affinity for the top three molecules (agonist BI-167107, neutral antagonist alprenolol and inverse agonist ICI 118,551). The results indicate agonist BI-167107 has the best binding affinity. MD simulation and free energy calculation are employed to investigate the dynamic interaction mechanism between the ligands and β2AR. The results show that the agonist BI-167107 also has the lowest binding free energy. This study can provide a new way to perform virtual screening effectively through integrating molecular docking based on grid computing, MD simulations and free energy calculations. The source codes of MolGridCal are freely available at http://molgridcal.codeplex.com. PMID:25229694

β-Adrenergic enhancement of neuronal excitability in the lateral amygdala is developmentally gated.

PubMed

Fink, Ann E; LeDoux, Joseph E

2018-05-01

Noradrenergic signaling in the amygdala is important for processing threats and other emotionally salient stimuli, and β-adrenergic receptor activation is known to enhance neuronal spiking in the lateral amygdala (LA) of juvenile animals. Nevertheless, intracellular recordings have not yet been conducted to determine the effect of β-adrenergic receptor activation on spike properties in the adult LA, despite the potential significance of developmental changes between adolescence and adulthood. Here we demonstrate that the β-adrenergic agonist isoproterenol (15 μM) enhances spike frequency in dorsal LA principal neurons of juvenile male C57BL/6 mice and fails to do so in strain- and sex-matched adults. Furthermore, we find that the age-dependent effect of isoproterenol on spike frequency is occluded by the GABA A receptor blocker picrotoxin (75 μM), suggesting that β-adrenergic receptors downregulate tonic inhibition specifically in juvenile animals. These findings indicate a significant shift during adolescence in the cellular mechanisms of β-adrenergic modulation in the amygdala. NEW & NOTEWORTHY β-Adrenergic receptors (β-ARs) in amygdala are important in processing emotionally salient stimuli. Most cellular recordings have examined juvenile animals, while behavioral data are often obtained from adults. We replicate findings showing that β-ARs enhance spiking of principal cells in the lateral amygdala of juveniles, but we fail to find this in adults. These findings have notable scientific and clinical implications regarding the noradrenergic modulation of threat processing, alterations of which underlie fear and anxiety disorders.

Targeted analysis and determination of β-agonists, hormones, glucocorticoid and psychiatric drugs in feed by liquid chromatography with electrospray ionization tandem mass spectrometry.

PubMed

Zhu, Yufei; Xie, Shuyu; Chen, Dongmei; Pan, Yuanhu; Qu, Wei; Wang, Xu; Liu, Zhenli; Peng, Dapeng; Huang, Lingli; Tao, Yanfei; Yuan, Zonghui

2016-07-01

A comprehensive strategy combining a quantitative method was developed for 30 banned drugs including β-agonists, hormones, glucocorticoid and psychiatric drugs in swine and chicken feeds. This rapid, simple and effective extraction method was based on matrix solid-phase dispersion and electrospray ionization tandem mass spectrometry. The quantitative method was validated after previous statistical optimization of the main parameters of matrix solid-phase dispersion. The limit of quantification of dopamine hydrochloride, chlormadinone acetate, melengestrol acetate, testosterone propionate, nandrolone and midazolam was 2 μg/kg and that of the other 24 drugs was 1 μg/kg. The recoveries of β-agonists, hormones, glucocorticoid and psychiatric drugs spiked in swine and chicken feeds at a concentration range of 1-8 μg/kg were above 70.1% with inter-day relative standard deviations less than 15.8%. The analytical strategy was applied to 100 feed samples collected from a local market in Wuhan (China). Clenbuterol, ractopamine and melengestrol acetate were identified and quantified at the level 0.2∼3.5 μg/kg. The rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of 30 banned drugs in swine and chicken feeds with advantages of simple pretreatment and environmental friendly nature. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pharmacotherapy and Children with Autism Spectrum Disorder: A Tutorial for Speech-Language Pathologists

ERIC Educational Resources Information Center

Self, Trisha L.; Hale, LaDonna S.; Crumrine, Daiquirie

2010-01-01

Purpose: The purpose of this tutorial is to provide speech-language pathologists (SLPs) with general information regarding the most commonly prescribed medications for children with autism spectrum disorder (ASD; e.g., central nervous system stimulants, noradrenergic reuptake inhibitors, alpha-2 adrenergic agonists, antipsychotics,…

Ractopamine uptake from soil by alfalfa (Medicago sativa) and wheat (Triticum aestivum)

USDA-ARS?s Scientific Manuscript database

Ractopamine, a beta adrenergic agonist, is approved to use as feed additive in swine (Paylean®), cattle (Optaflexx®), and turkey (Topmax®) to improve daily weight gain, increase feed efficiency, and produce leaner meat. Because of this economic advantage, ractopamine is widely used. The transfer o...

Fate and transport of the ß-adrenergic agonist ractopamine hydrochloride in soil-water systems

USDA-ARS?s Scientific Manuscript database

The feed additive ractopamine hydrochloride was fortified at four concentrations into batch vials containing soils that differed in both biological activity and organic matter (OM). Sampling of the liquid layer for 14 d demonstrated that ractopamine rapidly dissipated from the liquid layer. Less t...

Ractopamine uptake by alfalfa (Medicago sativa) and wheat (Triticum aestivum) from soil

USDA-ARS?s Scientific Manuscript database

Ractopamine is a beta adrenergic agonist used as a growth promoter in swine, cattle and turkeys. To test whether ractopamine has the potential to accumulate in plants grown in contaminated soil, a greenhouse study was conducted with alfalfa (Medicago sativa) and wheat (Triticum aestivum) grown in t...

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

NASA Technical Reports Server (NTRS)

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

1999-01-01

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

Contact dermatitis caused by intermediate products in the manufacture of clenbuterol, ranitidine base, and ranitidine hydrochloride.

PubMed

Romaguera, C; Grimalt, F; Vilaplana, J

1990-01-01

Clenbuterol, a beta antagonist, and ranitidine, a histamine-receptor antagonist, were associated with contact dermatitis in a chemist. The allergen in the former was an intermediate in the synthesis called beta. In the latter, intermediates and the finished base and hydrochloride were responsible.

beta-adrenergic effects on carbohydrate metabolism in the unweighted rat soleus muscle

NASA Technical Reports Server (NTRS)

Kirby, Christopher R.; Tischler, Marc E.

1990-01-01

The effect of unweighting on the response of the soleus-muscle carbohydrate metabolism to a beta-adrenergic agonist (isoproterenol) was investigated in rats that were subjected to three days of tail-cast suspension. It was found that isoproterenol promoted glycogen degradation in soleus from suspended rats to a higher degree than in weighted soleus from control rats, and had no effect in unweighted digitorum longus. However, isoproterenol did not have a greater inhibitory effect on the net uptake of tritium-labeled 2-deoxy-glucose by the unweighted soleus and that isoproterenol inhibited hexose phosphorylation less in the unweighted than in the control muscle.

Acute pesticide ingestion managed with yohimbine as a rescue therapy.

PubMed

Nasa, Prashant; Juneja, Deven

2016-12-01

Amitraz is used as a pesticide in agricultural and veterinary medicine. It is primarily a central α2 adrenergic agonist and known to cause central nervous system depression, convulsions, respiratory depression, and bradycardia on severe intoxication. We report a case of a 3-year-old child who presented with accidental ingestion of amitraz solution with signs of severe poisoning. There is no specific antidote of amitraz poisoning in humans, however, animal experiments with α2 adrenergic antagonists such as yohimbine and atimepazole have been successful. The child was managed besides intensive management with enteral yohimbine, and he regained consciousness in 18 h and was successfully weaned off mechanical ventilation.

Acute isoproterenol induces anxiety-like behavior in rats and increases plasma content of extracellular vesicles.

PubMed

Leo, Giuseppina; Guescini, Michele; Genedani, Susanna; Stocchi, Vilberto; Carone, Chiara; Filaferro, Monica; Sisti, Davide; Marcoli, Manuela; Maura, Guido; Cortelli, Pietro; Guidolin, Diego; Fuxe, Kjell; Agnati, Luigi Francesco

2015-04-01

Several clinical observations have demonstrated a link between heart rate and anxiety or panic disorders. In these patients, β-adrenergic receptor function was altered. This prompted us to investigate whether the β-adrenergic receptor agonist isoproterenol, at a dose that stimulates peripheral β-adrenergic system but has no effects at the central nervous system, can induce anxiety-like behavior in rats. Moreover, some possible messengers involved in the peripheral to brain communication were investigated. Our results showed that isoproterenol (5 mg kg(-1) i.p.) increased heart rate, evoked anxiety-like behavior, did not result in motor impairments and increased extracellular vesicle content in the blood. Plasma corticosterone level was unmodified as well as vesicular Hsp70 content. Vesicular miR-208 was also unmodified indicating a source of increased extracellular vesicles different from cardiomyocytes. We can hypothesize that peripheral extracellular vesicles might contribute to the β-adrenergic receptor-evoked anxiety-like behavior, acting as peripheral signals in modulating the mental state. Copyright © 2015 Elsevier Inc. All rights reserved.

Cancer cells become less deformable and more invasive with activation of β-adrenergic signaling

PubMed Central

Gill, Navjot Kaur; Nyberg, Kendra D.; Nguyen, Angelyn V.; Hohlbauch, Sophia V.; Geisse, Nicholas A.; Nowell, Cameron J.; Sloan, Erica K.

2016-01-01

ABSTRACT Invasion by cancer cells is a crucial step in metastasis. An oversimplified view in the literature is that cancer cells become more deformable as they become more invasive. β-adrenergic receptor (βAR) signaling drives invasion and metastasis, but the effects on cell deformability are not known. Here, we show that activation of β-adrenergic signaling by βAR agonists reduces the deformability of highly metastatic human breast cancer cells, and that these stiffer cells are more invasive in vitro. We find that βAR activation also reduces the deformability of ovarian, prostate, melanoma and leukemia cells. Mechanistically, we show that βAR-mediated cell stiffening depends on the actin cytoskeleton and myosin II activity. These changes in cell deformability can be prevented by pharmacological β-blockade or genetic knockout of the β2-adrenergic receptor. Our results identify a β2-adrenergic–Ca2+–actin axis as a new regulator of cell deformability, and suggest that the relationship between cell mechanical properties and invasion might be dependent on context. PMID:27875276

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.

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.

Dynamic denitrosylation via S-nitrosoglutathione reductase regulates cardiovascular function

PubMed Central

Beigi, Farideh; Gonzalez, Daniel R.; Minhas, Khalid M.; Sun, Qi-An; Foster, Matthew W.; Khan, Shakil A.; Treuer, Adriana V.; Dulce, Raul A.; Harrison, Robert W.; Saraiva, Roberto M.; Premer, Courtney; Schulman, Ivonne Hernandez; Stamler, Jonathan S.; Hare, Joshua M.

2012-01-01

Although protein S-nitrosylation is increasingly recognized as mediating nitric oxide (NO) signaling, roles for protein denitrosylation in physiology remain unknown. Here, we show that S-nitrosoglutathione reductase (GSNOR), an enzyme that governs levels of S-nitrosylation by promoting protein denitrosylation, regulates both peripheral vascular tone and β-adrenergic agonist-stimulated cardiac contractility, previously ascribed exclusively to NO/cGMP. GSNOR-deficient mice exhibited reduced peripheral vascular tone and depressed β-adrenergic inotropic responses that were associated with impaired β-agonist–induced denitrosylation of cardiac ryanodine receptor 2 (RyR2), resulting in calcium leak. These results indicate that systemic hemodynamic responses (vascular tone and cardiac contractility), both under basal conditions and after adrenergic activation, are regulated through concerted actions of NO synthase/GSNOR and that aberrant denitrosylation impairs cardiovascular function. Our findings support the notion that dynamic S-nitrosylation/denitrosylation reactions are essential in cardiovascular regulation. PMID:22366318

β2-Adrenergic Receptor Agonists Inhibit the Proliferation of 1321N1 Astrocytoma CellsS⃞

PubMed Central

Toll, L.; Jimenez, L.; Waleh, N.; Jozwiak, K.; Woo, A.Y.-H.; Xiao, R.-P.; Bernier, M.

2011-01-01

Astrocytomas and glioblastomas have been particularly difficult to treat and refractory to chemotherapy. However, significant evidence has been presented that demonstrates a decrease in astrocytoma cell proliferation subsequent to an increase in cAMP levels. The 1321N1 astrocytoma cell line, as well as other astrocytomas and glioblastomas, expresses β2-adrenergic receptors (β2-ARs) that are coupled to Gs activation and consequent cAMP production. Experiments were conducted to determine whether the β2-AR agonist (R,R′)-fenoterol and other β2-AR agonists could attenuate mitogenesis and, if so, by what mechanism. Receptor binding studies were conducted to characterize β2-AR found in 1321N1 and U118 cell membranes. In addition, cells were incubated with (R,R′)-fenoterol and analogs to determine their ability to stimulate intracellular cAMP accumulation and inhibit [3H]thymidine incorporation into the cells. 1321N1 cells contain significant levels of β2-AR as determined by receptor binding. (R,R′)-fenoterol and other β2-AR agonists, as well as forskolin, stimulated cAMP accumulation in a dose-dependent manner. Accumulation of cAMP induced a decrease in [3H]thymidine incorporation. There was a correlation between concentration required to stimulate cAMP accumulation and inhibit [3H]thymidine incorporation. U118 cells have a reduced number of β2-ARs and a concomitant reduction in the ability of β2-AR agonists to inhibit cell proliferation. These studies demonstrate the efficacy of β2-AR agonists for inhibition of growth of the astrocytoma cell lines. Because a significant portion of brain tumors contain β2-ARs to a greater extent than whole brain, (R,R′)-fenoterol, or some analog, may be useful in the treatment of brain tumors after biopsy to determine β2-AR expression. PMID:21071556

α2 Adrenergic receptor-mediated inhibition of thermogenesis.

PubMed

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

2013-01-30

α2 adrenergic receptor (α2-AR) agonists have been used as antihypertensive 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 area (rRPa) inhibited BAT sympathetic nerve activity (SNA) and BAT thermogenesis. Subsequent nanoinjection of the α2-AR antagonist idazoxan (6 nmol) into the rRPa reversed the clonidine-evoked inhibition of BAT SNA and BAT thermogenesis. Systemic administration of the α2-AR agonists dexmedetomidine (25 μg/kg, i.v.) and clonidine (100 μg/kg, i.v.) inhibited shivering EMGs, BAT SNA, and BAT thermogenesis, effects that were reversed by nanoinjection of idazoxan (6 nmol) into the rRPa. Dexmedetomidine (100 μg/kg, i.p.) prevented and reversed lipopolysaccharide-evoked (10 μg/kg, i.p.) 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 ventrolateral medulla neurons expressing 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.

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.

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

Epinephrine stimulation of anion secretion in the Calu-3 serous cell model

PubMed Central

Banga, Amiraj; Flaig, Stephanie; Lewis, Shanta; Winfree, Seth

2014-01-01

Calu-3 is a well-differentiated human bronchial cell line with the characteristics of the serous cells of airway submucosal glands. The submucosal glands play a major role in mucociliary clearance because they secrete electrolytes that facilitate airway hydration. Given the significance of both long- and short-term β-adrenergic receptor agonists in the treatment of respiratory diseases, it is important to determine the role of these receptors and their ligands in normal physiological function. The present studies were designed to characterize the effect of epinephrine, the naturally occurring β-adrenergic receptor agonist, on electrolyte transport of the airway serous cells. Interestingly, epinephrine stimulated two anion secretory channels, the cystic fibrosis transmembrane conductance regulator and a Ca2+-activated Cl− channel, with the characteristics of transmembrane protein 16A, thereby potentially altering mucociliary clearance via multiple channels. Consistent with the dual channel activation, epinephrine treatment resulted in increases in both intracellular cAMP and Ca2+. Furthermore, the present results extend previous reports indicating that the two anion channels are functionally linked. PMID:24705724

Effect of pioglitazone on vasopressor responses to adrenergic agonists and angiotensin II in diabetic and non-diabetic spontaneously hypertensive rats.

PubMed

Afzal, Sheryar; Sattar, Munavvar Abdul; Akhtar, Safia; Binti Abdullah, Nor Azizan; Eseyin, Olorunfemi A; Abdulla, Mohammed H; Johns, Edward James

2018-05-01

Pioglitazone, peroxisome proliferator-activated receptor (PPAR-γ) agonist, is a therapeutic drug for diabetes. Present study investigated the interaction between PPAR-γ and alpha adrenoceptors in modulating vasopressor responses to Angiotensin II (Ang II) and adrenergic agonists, in diabetic & non-diabetic Spontaneously Hypertensive Rats (SHRs). Diabetes was induced with an i.p injection of streptozotocin (40 mg/kg) in two groups (STZ-CON, STZ-PIO), whereas two groups remained non diabetic (ND-CO, ND-PIO). One diabetic and non-diabetic group received Pioglitazone (10mg/kg) orally for 21 days. On day 28, the animals were anaesthetized with sodium pentobarbitone (60mg/kg) and prepared for measurement of systemic haemodynamics. Basal mean arterial pressure of STZ-CON was higher than ND-CON, whereas following pioglitazone treatment, MAP was lower compared to respective controls. MAP responses to i.v administration of NA, PE, ME and ANG II were significantly lower in diabetic SHRs: STZ-CON vs ND-CON (35%). Pioglitazone significantly decreased responses to NA, PE, ME and ANG II in ND-PIO versus ND-CON by 63%. Responses to NA and ANG II were significantly attenuated in STZ-PIO vs. ND-PIO (40%). PPAR-γ regulates systemic hemodynamic in diabetic model and cross-talk relationship exists between PPAR-γ and α1-adrenoceptors, ANG II in systemic vasculature of SHRs.

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.

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

Src family kinases mediate the inhibition of substance P release in the rat spinal cord by μ-opioid receptors and GABA(B) receptors, but not α2 adrenergic receptors.

PubMed

Zhang, Guohua; Chen, Wenling; Marvizón, Juan Carlos G

2010-09-01

GABA(B) , μ-opioid and adrenergic α(2) receptors inhibit substance P release from primary afferent terminals in the dorsal horn. Studies in cell expression systems suggest that μ-opioid and GABA(B) receptors inhibit transmitter release from primary afferents by activating Src family kinases (SFKs), which then phosphorylate and inhibit voltage-gated calcium channels. This study investigated whether SFKs mediate the inhibition of substance P release by these three receptors. Substance P release was measured as neurokinin 1 receptor (NK1R) internalization in spinal cord slices and in vivo. In slices, NK1R internalization induced by high-frequency dorsal root stimulation was inhibited by the μ-opioid agonist DAMGO and the GABA(B) agonist baclofen. This inhibition was reversed by the SFK inhibitor PP1. NK1R internalization induced by low-frequency stimulation was also inhibited by DAMGO, but PP1 did not reverse this effect. In vivo, NK1R internalization induced by noxious mechanical stimulation of the hind paw was inhibited by intrathecal DAMGO and baclofen. This inhibition was reversed by intrathecal PP1, but not by the inactive PP1 analog PP3. PP1 produced no effect by itself. The α(2) adrenergic agonists medetomidine and guanfacine produced a small but statistically significant inhibition of NK1R internalization induced by low-frequency dorsal root stimulation. PP1 did not reverse the inhibition by guanfacine. These results show that SFKs mediate the inhibition of substance P release by μ-opioid and GABA(B) receptors, but not by α(2) receptors, which is probably mediated by the binding of G protein βγ subunits to calcium channels. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd. No claim to original US government works.

Alterations in vasodilator-stimulated phosphoprotein (VASP) phosphorylation: associations with asthmatic phenotype, airway inflammation and β2-agonist use

PubMed Central

Hastie, Annette T; Wu, Min; Foster, Gayle C; Hawkins, Gregory A; Batra, Vikas; Rybinski, Katherine A; Cirelli, Rosemary; Zangrilli, James G; Peters, Stephen P

2006-01-01

Background Vasodilator-stimulated phosphoprotein (VASP) mediates focal adhesion, actin filament binding and polymerization in a variety of cells, thereby inhibiting cell movement. Phosphorylation of VASP via cAMP and cGMP dependent protein kinases releases this "brake" on cell motility. Thus, phosphorylation of VASP may be necessary for epithelial cell repair of damage from allergen-induced inflammation. Two hypotheses were examined: (1) injury from segmental allergen challenge increases VASP phosphorylation in airway epithelium in asthmatic but not nonasthmatic normal subjects, (2) regular in vivo β2-agonist use increases VASP phosphorylation in asthmatic epithelium, altering cell adhesion. Methods Bronchial epithelium was obtained from asthmatic and non-asthmatic normal subjects before and after segmental allergen challenge, and after regularly inhaled albuterol, in three separate protocols. VASP phosphorylation was examined in Western blots of epithelial samples. DNA was obtained for β2-adrenergic receptor haplotype determination. Results Although VASP phosphorylation increased, it was not significantly greater after allergen challenge in asthmatics or normals. However, VASP phosphorylation in epithelium of nonasthmatic normal subjects was double that observed in asthmatic subjects, both at baseline and after challenge. Regularly inhaled albuterol significantly increased VASP phosphorylation in asthmatic subjects in both unchallenged and antigen challenged lung segment epithelium. There was also a significant increase in epithelial cells in the bronchoalveolar lavage of the unchallenged lung segment after regular inhalation of albuterol but not of placebo. The haplotypes of the β2-adrenergic receptor did not appear to associate with increased or decreased phosphorylation of VASP. Conclusion Decreased VASP phosphorylation was observed in epithelial cells of asthmatics compared to nonasthmatic normals, despite response to β-agonist. The decreased phosphorylation does not appear to be associated with a particular β2-adrenergic receptor haplotype. The observed decrease in VASP phosphorylation suggests greater inhibition of actin reorganization which is necessary for altering attachment and migration required during epithelial repair. PMID:16480498

Alterations in vasodilator-stimulated phosphoprotein (VASP) phosphorylation: associations with asthmatic phenotype, airway inflammation and beta2-agonist use.

PubMed

Hastie, Annette T; Wu, Min; Foster, Gayle C; Hawkins, Gregory A; Batra, Vikas; Rybinski, Katherine A; Cirelli, Rosemary; Zangrilli, James G; Peters, Stephen P

2006-02-15

Vasodilator-stimulated phosphoprotein (VASP) mediates focal adhesion, actin filament binding and polymerization in a variety of cells, thereby inhibiting cell movement. Phosphorylation of VASP via cAMP and cGMP dependent protein kinases releases this "brake" on cell motility. Thus, phosphorylation of VASP may be necessary for epithelial cell repair of damage from allergen-induced inflammation. Two hypotheses were examined: (1) injury from segmental allergen challenge increases VASP phosphorylation in airway epithelium in asthmatic but not nonasthmatic normal subjects, (2) regular in vivo beta2-agonist use increases VASP phosphorylation in asthmatic epithelium, altering cell adhesion. Bronchial epithelium was obtained from asthmatic and non-asthmatic normal subjects before and after segmental allergen challenge, and after regularly inhaled albuterol, in three separate protocols. VASP phosphorylation was examined in Western blots of epithelial samples. DNA was obtained for beta2-adrenergic receptor haplotype determination. Although VASP phosphorylation increased, it was not significantly greater after allergen challenge in asthmatics or normals. However, VASP phosphorylation in epithelium of nonasthmatic normal subjects was double that observed in asthmatic subjects, both at baseline and after challenge. Regularly inhaled albuterol significantly increased VASP phosphorylation in asthmatic subjects in both unchallenged and antigen challenged lung segment epithelium. There was also a significant increase in epithelial cells in the bronchoalveolar lavage of the unchallenged lung segment after regular inhalation of albuterol but not of placebo. The haplotypes of the beta2-adrenergic receptor did not appear to associate with increased or decreased phosphorylation of VASP. Decreased VASP phosphorylation was observed in epithelial cells of asthmatics compared to nonasthmatic normals, despite response to beta-agonist. The decreased phosphorylation does not appear to be associated with a particular beta2-adrenergic receptor haplotype. The observed decrease in VASP phosphorylation suggests greater inhibition of actin reorganization which is necessary for altering attachment and migration required during epithelial repair.

Effect of airway acidosis and alkalosis on airway vascular smooth muscle responsiveness to albuterol.

PubMed

Cancado, Jose E; Mendes, Eliana S; Arana, Johana; Horvath, Gabor; Monzon, Maria E; Salathe, Matthias; Wanner, Adam

2015-04-02

In vitro and animal experiments have shown that the transport and signaling of β2-adrenergic agonists are pH-sensitive. Inhaled albuterol, a hydrophilic β2-adrenergic agonist, is widely used for the treatment of obstructive airway diseases. Acute exacerbations of obstructive airway diseases can be associated with changes in ventilation leading to either respiratory acidosis or alkalosis thereby affecting albuterol responsiveness in the airway. The purpose of this study was to determine if airway pH has an effect on albuterol-induced vasodilation in the airway. Ten healthy volunteers performed the following respiratory maneuvers: quiet breathing, hypocapnic hyperventilation, hypercapnic hyperventilation, and eucapnic hyperventilation (to dissociate the effect of pH from the effect of ventilation). During these breathing maneuvers, exhaled breath condensate (EBC) pH and airway blood flow response to inhaled albuterol (ΔQ̇aw) were assessed. Mean ± SE EBC pH (units) and ΔQ̇aw (μl.min(-1).mL(-1)) were 6.4 ± 0.1 and 16.8 ± 1.9 during quiet breathing, 6.3 ± 0.1 and 14.5 ± 2.4 during eucapnic hyperventilation, 6.6 ± 0.2 and -0.2 ± 1.8 during hypocapnic hyperventilation (p = 0.02 and <0.01 vs. quiet breathing), and 5.9 ± 0.1 and 2.0 ± 1.5 during hypercapnic hyperventilation (p = 0.02 and <0.02 vs quiet breathing). Albuterol responsiveness in the airway as assessed by ΔQ̇aw is pH sensitive. The breathing maneuver associated with decreased and increased EBC pH both resulted in a decreased responsiveness independent of the level of ventilation. These findings suggest an attenuated response to hydrophilic β2-adrenergic agonists during airway disease exacerbations associated with changes in pH. Registered at clinicaltrials.gov: NCT01216748 .

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.

Commentary: Are alpha-2 agonist really effective in children with tics with comorbid ADHD? A commentary on Whittington et al. (2016).

PubMed

Bloch, Michael H

2016-09-01

In this issue, Whittington et al. (2016) present a systematic review that reports the efficacy of three primary treatments for children with Tourette syndrome (TS) - (a) α2-adrenergic receptor agonists; (b) antipsychotic medications; and (c) habit reversal training/comprehensive behavioral intervention. In this commentary, we highlight the large degree of heterogeneity observed in the meta-analysis of trials involving alpha-2 agonist medications and present possible explanations for the observed heterogeneity. Among these possible explanations is the possibility that presence of comorbid ADHD may moderate the efficacy of alpha-2 agonists in the treatment of tic disorder with the medications being more effective in patients with both conditions. The commentary reviews the evidence supporting this possible moderating effect of ADHD and discusses the implications for such a relationship. © 2016 Association for Child and Adolescent Mental Health.

Acute pesticide ingestion managed with yohimbine as a rescue therapy

PubMed Central

Nasa, Prashant; Juneja, Deven

2016-01-01

Amitraz is used as a pesticide in agricultural and veterinary medicine. It is primarily a central α2 adrenergic agonist and known to cause central nervous system depression, convulsions, respiratory depression, and bradycardia on severe intoxication. We report a case of a 3-year-old child who presented with accidental ingestion of amitraz solution with signs of severe poisoning. There is no specific antidote of amitraz poisoning in humans, however, animal experiments with α2 adrenergic antagonists such as yohimbine and atimepazole have been successful. The child was managed besides intensive management with enteral yohimbine, and he regained consciousness in 18 h and was successfully weaned off mechanical ventilation. PMID:28149034

PCBs Alter Dopamine Mediated Function in Aging Workers

DTIC Science & Technology

2010-01-01

sympathomimetic agents, beta-adrenergic blocking agents, angiotensin-converting enzyme inhibitors, COX-2 inhibitors, other non - steroidal anti - inflammatory ...other non - steroidal anti - inflammatory agents, opiate agonists, miscellaneous analgesics and antipyretics, thyroid agents and antithyroid agents. ⁎ p...fold from peak values during occupational PCB use but remain elevated (two-fold) compared to a similar-aged non -occupationally exposed population

Clenbuterol toxicity: a NSW poisons information centre experience.

PubMed

Brett, Jonathan; Dawson, Andrew H; Brown, Jared A

2014-03-03

To describe the epidemiology and toxicity of clenbuterol in exposures reported to the NSW Poisons Information Centre (NSWPIC). Retrospective observational study analysing data from all calls about clenbuterol exposure recorded in the NSWPIC database from 1 January 2004 to 31 December 2012. The NSWPIC coversthe Australian jurisdictions New South Wales, Tasmania and the Australian Capital Territory 24 hours a day and provides after-hours cover for the rest of Australia for 7 nights each fortnight. Total number of exposures, source of call (hospital, health care worker, member of the public), time from exposure to call, reasons for drug use, clinical features and advice given. Callers reported 63 exposures to clenbuterol, with a dramatic increase from three in 2008 to 27 in 2012. Of the 63 calls, 35 were from hospital, two from paramedics, one from general practice and 21 direct from the public. At least 53 patients (84%) required hospitalisation. The commonest reasons for use were bodybuilding and slimming. The most common features were tachycardia (24 patients), gastrointestinal disturbance (16) and tremor (11). Exposure was also associated with cardiotoxicity including one cardiac arrest in a 21-year-old man. Although a well recognised doping issue among elite athletes, clenbuterol use has spread out into the general public, especially during 2012, and should be considered in patients using bodybuilding or slimming products who present with protracted sympathomimetic features. The potential for misuse of this substance requires reconsideration of its current poison schedule registration and its availability.

Cardiotoxic and Cardioprotective Features of Chronic β-adrenergic Signaling

PubMed Central

Zhang, Xiaoying; Szeto, Christopher; Gao, Erhe; Tang, Mingxin; Jin, Jianguo; Fu, Qin; Makarewich, Catherine; Ai, Xiaojie; Li, Ying; Tang, Allen; Wang, Jenny; Gao, Hui; Wang, Fang; Ge, Xinyi Joy; Kunapuli, Satya P.; Zhou, Lin; Zeng, Chunyu; Xiang, Kevin Yang; Chen, Xiongwen

2012-01-01

Rationale In the failing heart, persistent β-adrenergic receptor (βAR) activation is thought to induce myocyte death by protein kinase A (PKA)-dependent and PKA-independent activation of calcium/calmodulin-dependent kinase II (CaMKII). β-Adrenergic signaling pathways are also capable of activating cardioprotective mechanisms. Objective This study used a novel PKA inhibitor peptide (PKI) to inhibit PKA activity to test the hypothesis that βAR signaling causes cell death through PKA-dependent pathways and cardioprotection through PKA-independent pathways. Methods and Results In PKI transgenic mice, chronic isoproterenol (ISO) failed to induce cardiac hypertrophy, fibrosis, myocyte apoptosis and depressed cardiac function. In cultured adult feline ventricular myocytes (AFVMs), PKA inhibition protected myocytes from death induced by β1-AR agonists by preventing cytosolic and SR Ca2+ overload and CaMKII activation. PKA inhibition revealed a cardioprotective role of β-adrenergic signaling via cAMP/EPAC /Rap1/Rac/ERK pathway. Selective PKA inhibition causes protection in the heart after myocardial infarction (MI) that was superior to β-blocker therapy. Conclusion These results suggest that selective block of PKA could be a novel heart failure therapy. PMID:23104882

Dexmedetomidine for Refractory Adrenergic Crisis in Familial Dysautonomia

PubMed Central

Dillon, Ryan C.; Palma, Jose-Alberto; Spalink, Christy L.; Altshuler, Diana; Norcliffe-Kaufmann, Lucy; Fridman, David; Papadopoulos, John; Kaufmann, Horacio

2016-01-01

Objective Adrenergic crises are a cardinal feature of familial dysautonomia (FD). Traditionally, adrenergic crisis have been treated with the sympatholytic agent clonidine or with benzodiazepines, which can cause excessive sedation and respiratory depression. Dexmedetomidine is an α2A-adrenergic agonist with greater selectivity and shorter half-life than clonidine. We aimed to evaluate the preliminary effectiveness and safety of intravenous dexmedetomidine in the treatment of refractory adrenergic crisis in patients with FD. Methods Retrospective chart review of patients with genetically confirmed FD who received intravenous dexmedetomidine for refractory adrenergic crises. The primary outcome was preliminary effectiveness of dexmedetomidine defined as change in blood pressure (BP) and heart rate (HR) 1-hour after the initiation of dexmedetomidine. Secondary outcomes included incidence of adverse events related to dexmedetomidine, hospital and intensive care unit (ICU) length of stay, and hemodynamic parameters 12-hours after dexmedetomidine cessation. Results Nine patients over 14 admissions were included in the final analysis. At 1-hour after the initiation of dexmedetomidine, systolic BP decreased from 160±7 to 122±7 mmHg (p=0.0005), diastolic BP decreased from 103±6 to 65±8 (p=0.0003), and HR decreased from 112±4 to 100±5 bpm (p=0.0047). The median total adverse events during dexmedetomidine infusion was 1 per admission. Median hospital length of stay was 9 days (IQR, 3 – 11 days) and median ICU length of stay was 7 days (IQR, 3 – 11 days). Conclusions Intravenous dexmedetomidine is safe in patients with FD and appears to be effective to treat refractory adrenergic crisis. Dexmedetomidine may be considered in FD patients who do not respond to conventional clonidine and benzodiazepine pharmacotherapy. PMID:27752785

Left ventricular assist device and drug therapy for the reversal of heart failure.

PubMed

Birks, Emma J; Tansley, Patrick D; Hardy, James; George, Robert S; Bowles, Christopher T; Burke, Margaret; Banner, Nicholas R; Khaghani, Asghar; Yacoub, Magdi H

2006-11-02

In patients with severe heart failure, prolonged unloading of the myocardium with the use of a left ventricular assist device has been reported to lead to myocardial recovery in small numbers of patients for varying periods of time. Increasing the frequency and durability of myocardial recovery could reduce or postpone the need for subsequent heart transplantation. We enrolled 15 patients with severe heart failure due to nonischemic cardiomyopathy and with no histologic evidence of active myocarditis. All had markedly reduced cardiac output and were receiving inotropes. The patients underwent implantation of left ventricular assist devices and were treated with lisinopril, carvedilol, spironolactone, and losartan to enhance reverse remodeling. Once regression of left ventricular enlargement had been achieved, the beta2-adrenergic-receptor agonist clenbuterol was administered to prevent myocardial atrophy. Eleven of the 15 patients had sufficient myocardial recovery to undergo explantation of the left ventricular assist device a mean (+/-SD) of 320+/-186 days after implantation of the device. One patient died of intractable arrhythmias 24 hours after explantation; another died of carcinoma of the lung 27 months after explantation. The cumulative rate of freedom from recurrent heart failure among the surviving patients was 100% and 88.9% 1 and 4 years after explantation, respectively. The quality of life as assessed by the Minnesota Living with Heart Failure Questionnaire score at 3 years was nearly normal. Fifty-nine months after explantation, the mean left ventricular ejection fraction was 64+/-12%, the mean left ventricular end-diastolic diameter was 59.4+/-12.1 mm, the mean left ventricular end-systolic diameter was 42.5+/-13.2 mm, and the mean maximal oxygen uptake with exercise was 26.3+/-6.0 ml per kilogram of body weight per minute. In this single-center study, we found that sustained reversal of severe heart failure secondary to nonischemic cardiomyopathy could be achieved in selected patients with the use of a left ventricular assist device and a specific pharmacologic regimen. Copyright 2006 Massachusetts Medical Society.

Effect of interleukin 13 on bronchial hyperresponsiveness and the bronchoprotective effect of beta-adrenergic bronchodilators and corticosteroids.

PubMed

Townley, Robert G; Gendapodi, Pradeep R; Qutna, Nidal; Evans, Joseph; Romero, Francisco A; Abel, Peter

2009-03-01

Fluticasone affects airway bronchial hyperresponsiveness (BHR) and enhances bronchodilation and bronchoprotection induced by beta-adrenergic agonists. Interleukin 13 (IL-13), however, induces BHR. To test the hypotheses that fluticasone inhibits BHR after either allergen sensitization or IL-13 administration and that fluticasone restores the bronchodilation and bronchoprotective effects of beta-agonists. The BHR to methacholine induced by IL-13 or ovalbumin was determined in BALB/c mice, and the provocation concentration of methacholine that caused an increase in enhanced pause in expiration of 200% (PC200) was calculated. We compared this response to methacholine in control mice with the response after treatment with IL-13 receptor alpha 2-IgGFc fusion protein (IL-13R alpha 2) (an IL-13 blocker), fluticasone, albuterol, salmeterol, fluticasone-albuterol, and fluticasone-salmeterol. IL-13R alpha 2 (PC200, 17.59) completely blocks the BHR-induced effects of IL-13 (PC200, 7.28; P < .005). After IL-13 therapy (PC200, 5.90; P < .005), 1 mg/mL of albuterol (PC200, 3.38; P = .33), fluticasone (PC200, 4.59; P = .40), or fluticasone plus 50 microg/mL of salmeterol (PC200, 5.59; P = .11) showed no significant bronchoprotection. In nonsensitized mice, fluticasone plus 0.25 microg/mL of salmeterol (PC200, 25.90; P < .005) showed significantly greater bronchoprotection than did salmeterol alone (PC200, 11.08; P = .26). Fluticasone plus 0.3 mg/mL of albuterol and fluticasone plus 1 mg/mL of albuterol were significantly more protective than was fluticasone or albuterol alone in ovalbumin-sensitized mice. The protective effects of fluticasone, beta-agonists, and fluticasone plus beta-agonists are significantly less in IL-13-treated mice than in nonsensitized or ovalbumin-sensitized mice.

Effects of liver depression and psychological stress on human uterine leiomyoma cells by an AR-cAMP-PKA signal transduction pathway.

PubMed

Xia, Tian; Li, Shuang; Ma, Ruihong; Guan, Sufen; Li, Jiacui; Li, Hongqin; Zhang, Hexin; Lin, Qiu; Zhao, Zhimei; Wang, Baojuan

2017-06-01

Based on the emotional theory of Traditional Chinese Medicine, and combined with the modern medicine theory of psychological stress, a research model of human uterine leiomyoma cells (ULM) was cultured in vitro to determine the effectiveness of adrenergic receptor (AR) agonists in human ULM cell growth. In addition, we studied the functional influence of "liver depression and psychological stress theory" on fibroid formation by intervening in the AR-cAMP-PKA signaling pathway. The intention was to establish a new method to prevent and cure fibroids through "liver depression and psychological stress theory" and provide an experimental basis for the Traditional Chinese Medicine emotional theory. Primary human ULM cells were enriched by collagenase digestion. Immunohistochemistry and hematoxylin and eosin (HE) staining were used for cytological identification. Using this model, we studied intervention using specific AR agonists on ULM cells to observe the influence of "liver depression and psychological stress theory" on estrogen receptor (ER), progesterone receptor (PR), vascular endothelial growth factor (VEGF) and fibroblast growth factors (FGF). Norepinephrine (NE) and epinephrine (E) are adrenergic receptor agonists. They promoted ULM cell proliferation and increased the levels of ER, PR, VEGF and FGF. In contrast, isoproterenol (ISO) inhibited ULM cell proliferation and decreased the levels of ER, PR, VEGF and FGF. The protein expression of cAMP and PKA in ULM cells was reduced and the levels of ER, PR, VEGF and FGF were increased when co-treatment with the α-AR blocker (phentolamine). The β-AR blocker (metoprolol) displayed an opposite effect. AR agonists modulated ER, PR, VEGF and FGF levels in ULM cells in an AR-cAMP-PKA-dependent signaling pathways to influence fibroid occurrence and development. Copyright © 2017. Published by Elsevier B.V.

Agonistic autoantibodies as vasodilators in orthostatic hypotension: a new mechanism.

PubMed

Li, Hongliang; Kem, David C; Reim, Sean; Khan, Muneer; Vanderlinde-Wood, Megan; Zillner, Caitlin; Collier, Daniel; Liles, Campbell; Hill, Michael A; Cunningham, Madeleine W; Aston, Christopher E; Yu, Xichun

2012-02-01

Agonistic autoantibodies to the β-adrenergic and muscarinic receptors are a novel investigative and therapeutic target for certain orthostatic disorders. We have identified the presence of autoantibodies to β2-adrenergic and/or M3 muscarinic receptors by ELISA in 75% (15 of 20) of patients with significant orthostatic hypotension. Purified serum IgG from all 20 of the patients and 10 healthy control subjects were examined in a receptor-transfected cell-based cAMP assay for β2 receptor activation and β-arrestin assay for M3 receptor activation. There was a significant increase in IgG-induced activation of β2 and M3 receptors in the patient group compared with controls. A dose response was observed for both IgG activation of β2 and M3 receptors and inhibition of their activation with the nonselective β blocker propranolol and muscarinic blocker atropine. The antibody effects on β2 and/or M3 (via production of NO) receptor-mediated vasodilation were studied in a rat cremaster resistance arteriole assay. Infusion of IgG from patients with documented β2 and/or M3 receptor agonistic activity produced a dose-dependent vasodilation. Sequential addition of the β-blocker propranolol and the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester partially inhibited IgG-induced vasodilation (percentage of maximal dilatory response: from 57.7±10.4 to 35.3±4.6 and 24.3±5.8, respectively; P<0.01; n=3), indicating that antibody activation of vascular β2 and/or M3 receptors may contribute to systemic vasodilation. These data support the concept that circulating agonistic autoantibodies serve as vasodilators and may cause or exacerbate orthostatic hypotension.

Different mechanisms of action of beta2-adrenergic receptor agonists: a comparison of reproterol, fenoterol and salbutamol on monocyte cyclic-AMP and leukotriene B4 production in vitro.

PubMed

Juergens, Uwe R; Stöber, M; Libertus, H; Darlath, W; Gillissen, A; Vetter, H

2004-07-30

Beta2-adrenergic receptor agonists have several effects on airway function, most of which are mediated in a variety of cell types resulting in increased c-AMP-production and inhibition of inflammatory mediator production. However, their stimulating effects on cAMP-production became known to be inversed by increasing phosphodiesterase (PDE) activity and degradation of cAMP. Therefore, in this study we have evaluated the efficacy of reproterol, a dual acting beta2-adrenoceptor agonist and PDE-inhibitor, as compared to salbutamol and fenoterol with respect to production of cAMP and LTB4 in cultured monocytes. Isolated human monocytes (10(5)/ml) were incubated (n = 9) in suspension with beta2-adrenoceptor agonists (10(-10) -10(-4) M) for 30 minutes with and without IBMX. Then, cAMP production was determined following treatment with Triton-X100. Production of LTB4 was measured following incubation of beta2-adrenoceptor agonists for 4 hrs in the presence of LPS (10 mg/ml). cAMP and LTB subset 4 were measured in culture supernatants by enzyme immunoassay. At 10(-5) M, production of cAMP was significantly stimulated by reproterol > fenoterol > salbutamol in a dose-dependent manner to an extent of *128%, *65%, 13% (*p<0.04) respectively. In contrast, LTB4-production was inhibited significantly to a similar degree by salbutamol and reproterol in a dose-dependent manner by 59% and 49% (10(-5) M, p<0.03), respectively, with decreasing inhibition (15%) after fenoterol. Following co-incubation with IBMX, cAMP production only increased significantly (p<0.002) after fenoterol (+110%) compared to salbutamol (+29%) and reproterol (+50%) (ANOVA, p<0.001). These data suggest effects of the theophylline constituent of reproterol to inhibit adenylyl cyclase induced phosphodiesterase activity. The advantageous synergistic effects of reproterol on cAMP-production need to be further explored in trials.

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.

Complete prevention of radiation-induced dermatitis using topical adrenergic vasoconstrictors.

PubMed

Fahl, William E

2016-12-01

Radiation dermatitis is a commonly occurring, painful, side effect of cancer radiotherapy that causes some patients to withdraw from the radiotherapy course. Our goal was to test and optimize topical application of an adrenergic vasoconstrictor to rat skin in a preclinical test to prevent radiation-induced dermatitis. A radiation dermatitis assay was developed in which 17.2 Gy to a 1.5 × 3.0 cm rectangle on the clipped dorsal back of rats yielded Grade 3 radiation dermatitis over the irradiated area 13 days later. Single, topical applications of each of three adrenergic vasoconstrictors, epinephrine, norepinephrine, or phenylephrine, in various vehicle formulations, doses, and application schedules, were tested to determine their efficacy in preventing radiation dermatitis. Each of the three adrenergic agonists conferred 100 % prevention of radiation dermatitis in linear, dose-dependent manners and their EC 50 potencies in preventing radiation dermatitis correlated well with their individual K d association constants for binding to mammalian α-adrenergic receptors. Topical vasoconstrictor application as little as 3-12 min before irradiation gave 80-100 % prevention, respectively, of radiation dermatitis. There was a strong correlation between the extent (0-100 %) of skin blanch present in skin immediately before irradiation and prevention of radiation dermatitis scored 13 days after irradiation. The data presented here demonstrate that topical application of adrenergic vasoconstrictors to rat skin before a large, 17.2 Gy, radiation insult confers 100 % protection against radiation dermatitis and support ongoing clinical trials and commercial development of a vasoconstrictor-based product to prevent radiotherapy-induced dermatitis.

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

PubMed

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

2016-10-01

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

Leucine Stimulates Insulin Secretion via Down-regulation of Surface Expression of Adrenergic α2A Receptor through the mTOR (Mammalian Target of Rapamycin) Pathway

PubMed Central

Yang, Jun; Dolinger, Michael; Ritaccio, Gabrielle; Mazurkiewicz, Joseph; Conti, David; Zhu, Xinjun; Huang, Yunfei

2012-01-01

The amino acid leucine is a potent secretagogue, capable of inducing insulin secretion. It also plays an important role in the regulation of mTOR activity, therefore, providing impetus to investigate if a leucine-sensing mechanism in the mTOR pathway is involved in insulin secretion. We found that leucine-induced insulin secretion was inhibited by both the mTOR inhibitor rapamycin as well as the adrenergic α2 receptor agonist clonidine. We also demonstrated that leucine down-regulated the surface expression of adrenergic α2A receptor via activation of the mTOR pathway. The leucine stimulatory effect on insulin secretion was attenuated in diabetic Goto-Kakizaki rats that overexpress adrenergic α2A receptors, confirming the role of leucine in insulin secretion. Thus, our data demonstrate that leucine regulates insulin secretion by modulating adrenergic α2 receptors through the mTOR pathway. The role of the mTOR pathway in metabolic homeostasis led us to a second important finding in this study; retrospective analysis of clinical data showed that co-administration of rapamycin and clonidine was associated with an increased incidence of new-onset diabetes in renal transplantation patients over those receiving rapamycin alone. We believe that inhibition of mTOR by rapamycin along with activation of adrenergic α2 receptors by clonidine represents a double-hit to pancreatic islets that synergistically disturbs glucose homeostasis. This new insight may have important implications for the clinical management of renal transplant patients. PMID:22645144

Biomechanical hearts: muscular blood pumps, performed in a 1-step operation, and trained under support of clenbuterol.

PubMed

Guldner, N W; Klapproth, P; Grossherr, M; Brügge, A; Sheikhzadeh, A; Tölg, R; Rumpel, E; Noel, R; Sievers, H H

2001-08-07

As shown previously in goats, clenbuterol increased the power of electrically conditioned skeletal muscle ventricles (SMVs) of clinically relevant size (150 mL), which were constructed around a mock system. They pumped against a pressure of 60 to 70 mm Hg immediately during surgery and up to several months after, finally at >1 L/min. SMVs without clenbuterol administration failed. Thus, we expected that clenbuterol-supported SMVs might become integrated into the circulation by a 1-step operation instead of the 2-step procedure required up to now. In adult Boer goats (n=5), latissimus dorsi muscle was wrapped around a polyurethane chamber of 150 mL that was connected to the descending aorta. This muscular flow-through pumping chamber containing a stabilizing inner layer (called a biomechanical heart [BMH]) was formed and immediately made to work against a systemic load with the support of clenbuterol (5x150 microg/wk). During surgery, the mean stroke volume of BMHs was 53.8+/-22.4 mL. One month after surgery, in peripheral arterial pressure, the mean diastolic (P(MD)) and minimal diastolic (P(min)) pressures of BMH-supported heart cycles differed significantly from unsupported ones (P(MD)=+2.9+/-1.1 mm Hg [P<0.04], P(min)=-2.4+/-0.9 mm Hg [P<0.04]). After BMH-supported heart contractions, the subsequent maximal rate of pressure generation, dP/dt(max), increased by 20.5+/-8.1% (P<0.02). One BMH, catheterized 132 days after surgery, shifted a volume of 34.8 mL per beat and 1.4 L/min with a latissimus dorsi muscle of 330 g. Depending on duration of training, the percentage of myosin heavy chain type 1 ranged between 31% and 100%. Under support of clenbuterol, BMHs of a clinically relevant size can be trained effectively in the systemic circulation after a 1-step operation and offer the prospect of a sufficient volume shift and probably unloading of the left ventricle.

Mechanism of ion transport by avian salt gland primary cell cultures.

PubMed

Lowy, R J; Dawson, D C; Ernst, S A

1989-06-01

Confluent sheets formed from primary culture of avian salt gland secretory cells exhibit a short-circuit current (Isc) in response to cholinergic and beta-adrenergic stimulation [Lowy, R. J., D. C. Dawson, and S. A. Ernst. Am J. Physiol. 249 (Cell Physiol. 18): C41-C47, 1985]. To establish the ionic basis for the Isc, transmural fluxes of 22Na and 36Cl were measured. Under short-circuit conditions there was little net flux of either ion in the absence of agonists. Addition of carbachol elevated net serosal-to-mucosal Cl flux to 1.71 mu eq.h-1.cm-2, whereas a smaller increase to 0.85 mu eq.h-1.cm-2 occurred with isoproterenol. Neither agonist altered net Na flux. The stimulated Isc accounted for 70% of the net Cl flux induced by carbachol and nearly 100% of that induced by isoproterenol. Replacement of Cl by gluconate or Na by choline abolished (carbachol) or greatly reduced (isoproterenol) the Isc, which could be restored in a dose-dependent fashion by ion restitution. Active ion transport was preferentially inhibited by basal (vs. apical) addition of ouabain, furosemide, or barium. The results provide evidence that cholinergic and beta-adrenergic agonists elicit active transmural Cl secretion. They further suggest that transport is dependent on the Na+-K+-adenosine-triphosphatase, a Na-Cl cotransport process, and a basal K conductance, all features of a secondary active Cl secretory mechanism.

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.

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

PubMed

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

2012-12-01

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

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.

Effect of beta-adrenergic stimulation on whole-body and abdominal subcutaneous adipose tissue lipolysis in lean and obese men.

PubMed

Jocken, J W E; Goossens, G H; van Hees, A M J; Frayn, K N; van Baak, M; Stegen, J; Pakbiers, M T W; Saris, W H M; Blaak, E E

2008-02-01

Obesity is characterised by increased triacylglycerol storage in adipose tissue. There is in vitro evidence for a blunted beta-adrenergically mediated lipolytic response in abdominal subcutaneous adipose tissue (SAT) of obese individuals and evidence for this at the whole-body level in vivo. We hypothesised that the beta-adrenergically mediated effect on lipolysis in abdominal SAT is also impaired in vivo in obese humans. We investigated whole-body and abdominal SAT glycerol metabolism in vivo during 3 h and 6 h [2H5]glycerol infusions. Arterio-venous concentration differences were measured in 13 lean and ten obese men after an overnight fast and during intravenous infusion of the non-selective beta-adrenergic agonist isoprenaline [20 ng (kg fat free mass)(-1) min(-1)]. Lean and obese participants showed comparable fasting glycerol uptake by SAT (9.7+/-3.4 vs 9.3+/-2.5% of total release, p=0.92). Furthermore, obese participants showed an increased whole-body beta-adrenergically mediated lipolytic response versus lean participants. However, their fasting lipolysis was blunted [glycerol rate of appearance: 7.3+/-0.6 vs 13.1+/-0.9 micromol (kg fat mass)(-1) min(-1), p<0.01], as was the beta-adrenergically mediated lipolytic response per unit SAT [Delta total glycerol release: 140+/-71 vs 394+/-112 nmol (100 g tissue)(-1) min(-1), p<0.05] compared with lean participants. Net triacylglycerol flux tended to increase in obese compared with lean participants during beta-adrenergic stimulation [Delta net triacylglycerol flux: 75+/-32 vs 16+/-11 nmol (100 g tissue)(-1) min(-1), p=0.06]. We demonstrated in vivo that beta-adrenergically mediated lipolytic response is impaired systematically and in abdominal SAT of obese versus lean men. This may be important in the development or maintenance of increased triacylglycerol stores and obesity.

β-Adrenergic stimulation increases the intra-sarcoplasmic reticulum Ca2+ threshold for Ca2+ wave generation

PubMed Central

Domeier, Timothy L; Maxwell, Joshua T; Blatter, Lothar A

2012-01-01

β-Adrenergic signalling induces positive inotropic effects on the heart that associate with pro-arrhythmic spontaneous Ca2+ waves. A threshold level of sarcoplasmic reticulum (SR) Ca2+ ([Ca2+]SR) is necessary to trigger Ca2+ waves, and whether the increased incidence of Ca2+ waves during β-adrenergic stimulation is due to an alteration in this threshold remains controversial. Using the low-affinity Ca2+ indicator fluo-5N entrapped within the SR of rabbit ventricular myocytes, we addressed this controversy by directly monitoring [Ca2+]SR and Ca2+ waves during β-adrenergic stimulation. Electrical pacing in elevated extracellular Ca2+ ([Ca2+]o= 7 mm) was used to increase [Ca2+]SR to the threshold where Ca2+ waves were consistently observed. The β-adrenergic agonist isoproterenol (ISO; 1 μm) increased [Ca2+]SR well above the control threshold and consistently triggered Ca2+ waves. However, when [Ca2+]SR was subsequently lowered in the presence of ISO (by lowering [Ca2+]o to 1 mm and partially inhibiting sarcoplasmic/endoplasmic reticulum calcium ATPase with cyclopiazonic acid or thapsigargin), Ca2+ waves ceased to occur at a [Ca2+]SR that was higher than the control threshold. Furthermore, for a set [Ca2+]SR level the refractoriness of wave occurrence (Ca2+ wave latency) was prolonged during β-adrenergic stimulation, and was highly dependent on the extent that [Ca]SR exceeded the wave threshold. These data show that acute β-adrenergic stimulation increases the [Ca2+]SR threshold for Ca2+ waves, and therefore the primary cause of Ca2+ waves is the robust increase in [Ca2+]SR above this higher threshold level. Elevation of the [Ca2+]SR wave threshold and prolongation of wave latency represent potentially protective mechanisms against pro-arrhythmogenic Ca2+ release during β-adrenergic stimulation. PMID:22988136

Effects feeding zilpaterol hydrochloride on growth performance, fillet yeild, and body composition of rainbow trout, nile, tilapia, and channel catfish

USDA-ARS?s Scientific Manuscript database

Zilpaterol hydrochloride (ZH) is a potent ß-adrenergic agonist (BAA) that has been used in feedlot cattle to increase average daily gain, feed efficiency, yield of trimmed cuts, and dress out percent. While positive effects of ZH have been observed in cattle, there have been no reports of this prod...

Epac Activation Initiates Associative Odor Preference Memories in the Rat Pup

ERIC Educational Resources Information Center

Grimes, Matthew T.; Powell, Maria; Gutierrez, Sandra Mohammed; Darby-King, Andrea; Harley, Carolyn W.; McLean, John H.

2015-01-01

Here we examine the role of the exchange protein directly activated by cAMP (Epac) in ß-adrenergic-dependent associative odor preference learning in rat pups. Bulbar Epac agonist (8-pCPT-2-O-Me-cAMP, or 8-pCPT) infusions, paired with odor, initiated preference learning, which was selective for the paired odor. Interestingly, pairing odor with Epac…

Role of myometrial activity in sperm transport through the genital tract and in fertilization in sows.

PubMed

Langendijk, P; Bouwman, E G; Kidson, A; Kirkwood, R N; Soede, N M; Kemp, B

2002-05-01

The effects of stimulation and suppression of uterine contractility at about the time of insemination on sperm distribution and fertilization in multiparous sows are described. For assessment of fertilization, sows were inseminated about 28 h before (synchronized) ovulation and killed at day 5 after ovulation (n = 53). For assessment of sperm distribution, sows were inseminated about 20 h before expected ovulation and were killed 12 h later (n = 26). At 10 min before insemination, sows received an intrauterine infusion of one of three solutions: (i) saline (control); (ii) 0.60 mg clenbuterol hydrochloride to suppress contractility; or (iii) 1 mg cloprostenol to stimulate contractility. Both clenbuterol and cloprostenol reduced median fertilization rate (P < 0.05) and median number of accessory sperm cells (P < 0.05). Distribution of sperm cells was also affected by treatments. Clenbuterol increased, and cloprostenol decreased, the number of sperm cells (P < 0.05) in the proximal 20 cm of the uterine horn and in the uterotubal junction. In addition, clenbuterol tended to increase and cloprostenol tended to decrease the number of sperm cells in the isthmus, although these effects were not significant. However, relative to the number of sperm cells in the uterus, clenbuterol treatment reduced the number of sperm cells in the uterotubal junction and oviduct, in contrast to cloprostenol. Cloprostenol increased the reflux of semen during insemination. It is hypothesized that suppression of uterine contractility increases transuterine transport time, reducing the ability of sperm cells to enter the uterotubal junction and the oviduct. Stimulation of uterine contractility above a certain level probably increases reflux and impedes transuterine transport of sufficient numbers of sperm cells.

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.

G Protein-coupled Receptor Kinases of the GRK4 Protein Subfamily Phosphorylate Inactive G Protein-coupled Receptors (GPCRs).

PubMed

Li, Lingyong; Homan, Kristoff T; Vishnivetskiy, Sergey A; Manglik, Aashish; Tesmer, John J G; Gurevich, Vsevolod V; Gurevich, Eugenia V

2015-04-24

G protein-coupled receptor (GPCR) kinases (GRKs) play a key role in homologous desensitization of GPCRs. It is widely assumed that most GRKs selectively phosphorylate only active GPCRs. Here, we show that although this seems to be the case for the GRK2/3 subfamily, GRK5/6 effectively phosphorylate inactive forms of several GPCRs, including β2-adrenergic and M2 muscarinic receptors, which are commonly used as representative models for GPCRs. Agonist-independent GPCR phosphorylation cannot be explained by constitutive activity of the receptor or membrane association of the GRK, suggesting that it is an inherent ability of GRK5/6. Importantly, phosphorylation of the inactive β2-adrenergic receptor enhanced its interactions with arrestins. Arrestin-3 was able to discriminate between phosphorylation of the same receptor by GRK2 and GRK5, demonstrating preference for the latter. Arrestin recruitment to inactive phosphorylated GPCRs suggests that not only agonist activation but also the complement of GRKs in the cell regulate formation of the arrestin-receptor complex and thereby G protein-independent signaling. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Cell contact as an independent factor modulating cardiac myocyte hypertrophy and survival in long-term primary culture

NASA Technical Reports Server (NTRS)

Clark, W. A.; Decker, M. L.; Behnke-Barclay, M.; Janes, D. M.; Decker, R. S.

1998-01-01

Cardiac myocytes maintained in cell culture develop hypertrophy both in response to mechanical loading as well as to receptor-mediated signaling mechanisms. However, it has been shown that the hypertrophic response to these stimuli may be modulated through effects of intercellular contact achieved by maintaining cells at different plating densities. In this study, we show that the myocyte plating density affects not only the hypertrophic response and features of the differentiated phenotype of isolated adult myocytes, but also plays a significant role influencing myocyte survival in vitro. The native rod-shaped phenotype of freshly isolated adult myocytes persists in an environment which minimizes myocyte attachment and spreading on the substratum. However, these conditions are not optimal for long-term maintenance of cultured adult cardiac myocytes. Conditions which promote myocyte attachment and spreading on the substratum, on the other hand, also promote the re-establishment of new intercellular contacts between myocytes. These contacts appear to play a significant role in the development of spontaneous activity, which enhances the redevelopment of highly differentiated contractile, junctional, and sarcoplasmic reticulum structures in the cultured adult cardiomyocyte. Although it has previously been shown that adult cardiac myocytes are typically quiescent in culture, the addition of beta-adrenergic agonists stimulates beating and myocyte hypertrophy, and thereby serves to increase the level of intercellular contact as well. However, in densely-plated cultures with intrinsically high levels of intercellular contact, spontaneous contractile activity develops without the addition of beta-adrenergic agonists. In this study, we compare the function, morphology, and natural history of adult feline cardiomyocytes which have been maintained in cultures with different levels of intercellular contact, with and without the addition of beta-adrenergic agonists. Intercellular contact, communication, and transmission of contractile forces between myocytes appears to play a primary role in remodeling the 2-dimensional cell layer into a parallel alignment of elongated myocytes with highly developed intercalated disk-like junctions. This highly differentiated state is very stable, and cultures which achieve this state exhibit significantly greater longevity than more sparsely plated myocytes. These myocytes typically continue beating, and survive from 6 to more than 12 weeks in culture. When this level of contact and differentiation are not achieved, even among beta-adrenergic stimulated myocytes, contractile activity is not sustained, myofibrils atrophy, there is little or no development of junctional complexes, and the period of myocyte viability is typically no more than 5 weeks in vitro.

2D-QSAR and 3D-QSAR/CoMSIA Studies on a Series of (R)-2-((2-(1H-Indol-2-yl)ethyl)amino)-1-Phenylethan-1-ol with Human β₃-Adrenergic Activity.

PubMed

Apablaza, Gastón; Montoya, Luisa; Morales-Verdejo, Cesar; Mellado, Marco; Cuellar, Mauricio; Lagos, Carlos F; Soto-Delgado, Jorge; Chung, Hery; Pessoa-Mahana, Carlos David; Mella, Jaime

2017-03-05

The β₃ adrenergic receptor is raising as an important drug target for the treatment of pathologies such as diabetes, obesity, depression, and cardiac diseases among others. Several attempts to obtain selective and high affinity ligands have been made. Currently, Mirabegron is the only available drug on the market that targets this receptor approved for the treatment of overactive bladder. However, the FDA (Food and Drug Administration) in USA and the MHRA (Medicines and Healthcare products Regulatory Agency) in UK have made reports of potentially life-threatening side effects associated with the administration of Mirabegron, casting doubts on the continuity of this compound. Therefore, it is of utmost importance to gather information for the rational design and synthesis of new β₃ adrenergic ligands. Herein, we present the first combined 2D-QSAR (two-dimensional Quantitative Structure-Activity Relationship) and 3D-QSAR/CoMSIA (three-dimensional Quantitative Structure-Activity Relationship/Comparative Molecular Similarity Index Analysis) study on a series of potent β₃ adrenergic agonists of indole-alkylamine structure. We found a series of changes that can be made in the steric, hydrogen-bond donor and acceptor, lipophilicity and molar refractivity properties of the compounds to generate new promising molecules. Finally, based on our analysis, a summary and a regiospecific description of the requirements for improving β₃ adrenergic activity is given.

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.

Osmotic versus adrenergic control of ion transport by ionocytes of Fundulus heteroclitus in the cold.

PubMed

Tait, Janet C; Mercer, Evan W; Gerber, Lucie; Robertson, George N; Marshall, William S

2017-01-01

In eurythermic vertebrates, acclimation to the cold may produce changes in physiological control systems. We hypothesize that relatively direct osmosensitive control will operate better than adrenergic receptor mediated control of ion transport in cold vs. warm conditions. Fish were acclimated to full strength seawater (SW) at 21°C and 5°C for four weeks, gill samples and blood were taken and opercular epithelia mounted in Ussing style chambers. Short-circuit current (I sc ) at 21°C and 5°C (measured at acclimation temperature), was significantly inhibited by the α 2 -adrenergic agonist clonidine but the ED 50 dose was significantly higher in cold conditions (93.8±16.4nM) than in warm epithelia (47.8±8.1nM) and the maximum inhibition was significantly lower in cold (-66.1±2.2%) vs. warm conditions (-85.6±1.3%), indicating lower sensitivity in the cold. β-Adrenergic responses were unchanged. Hypotonic inhibition of I sc , was higher in warm acclimated (-95%), compared to cold acclimated fish (-75%), while hypertonic stimulations were the same, indicating equal responsiveness to hyperosmotic stimuli. Plasma osmolality was significantly elevated in cold acclimated fish and, by TEM, gill ionocytes from cold acclimated fish had significantly shorter mitochondria. These data are consistent with a shift in these eurythermic animals from complex adrenergic control to relatively simple biomechanical osmotic control of ion secretion in the cold. Copyright © 2016. Published by Elsevier Inc.

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.

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

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

α1A-Subtype adrenergic agonist therapy for the failing right ventricle.

PubMed

Cowley, Patrick M; Wang, Guanying; Joshi, Sunil; Swigart, Philip M; Lovett, David H; Simpson, Paul C; Baker, Anthony J

2017-12-01

Failure of the right ventricle (RV) is a serious disease with a poor prognosis and limited treatment options. Signaling by α 1 -adrenergic receptors (α 1 -ARs), in particular the α 1A -subtype, mediate cardioprotective effects in multiple heart failure models. Recent studies have shown that chronic treatment with the α 1A -subtype agonist A61603 improves function and survival in a model of left ventricular failure. The goal of the present study was to determine if chronic A61603 treatment is beneficial in a RV failure model. We used tracheal instillation of the fibrogenic antibiotic bleomycin in mice to induce pulmonary fibrosis, pulmonary hypertension, and RV failure within 2 wk. Some mice were chronically treated with a low dose of A61603 (10 ng·kg -1 ·day -1 ). In the bleomycin model of RV failure, chronic A61603 treatment was associated with improved RV fractional shortening and greater in vitro force development by RV muscle preparations. Cell injury markers were reduced with A61603 treatment (serum cardiac troponin I, RV fibrosis, and expression of matrix metalloproteinase-2). RV oxidative stress was reduced (using the probes dihydroethidium and 4-hydroxynonenal). Consistent with lowered RV oxidative stress, A61603 was associated with an increased level of the cellular antioxidant superoxide dismutase 1 and a lower level of the prooxidant NAD(P)H oxidase isoform NOX4. In summary, in the bleomycin model of RV failure, chronic A61603 treatment reduced RV oxidative stress, RV myocyte necrosis, and RV fibrosis and increased both RV function and in vitro force development. These findings suggest that in the context of pulmonary fibrosis, the α 1A -subtype is a potential therapeutic target to treat the failing RV. NEW & NOTEWORTHY Right ventricular (RV) failure is a serious disease with a poor prognosis and no effective treatments. In the mouse bleomycin model of RV failure, we tested the efficacy of a treatment using the α 1A -adrenergic receptor subtype agonist A61603. Chronic A61603 treatment improved RV contraction and reduced multiple indexes of RV injury, suggesting that the α 1A -subtype is a therapeutic target to treat RV failure.

The effect of polymorphisms of the beta(2)-adrenergic receptor on the response to regular use of albuterol in asthma.

PubMed

Israel, E; Drazen, J M; Liggett, S B; Boushey, H A; Cherniack, R M; Chinchilli, V M; Cooper, D M; Fahy, J V; Fish, J E; Ford, J G; Kraft, M; Kunselman, S; Lazarus, S C; Lemanske, R F; Martin, R J; McLean, D E; Peters, S P; Silverman, E K; Sorkness, C A; Szefler, S J; Weiss, S T; Yandava, C N

2000-07-01

Inhaled beta-adrenergic agonists are the most commonly used medications for the treatment of asthma although there is evidence that regular use may produce adverse effects in some patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect regulation of the receptor. Smaller studies examining the effects of such polymorphisms on the response to beta-agonist therapy have produced inconsistent results. We examined whether polymorphisms at codon 16 (beta(2)-AR-16) and codon 27 (beta(2)-AR-27) of the beta(2)-AR might affect the response to regular versus as-needed use of albuterol by genotyping the 190 asthmatics who had participated in a trial examining the effects of regular versus as needed albuterol use. During the 16-wk treatment period there was a small decline in morning peak expiratory flow in patients homozygous for arginine at B(2)-AR-16 (Arg/Arg) who used albuterol regularly. This effect was magnified during a 4-wk run out period, during which all patients returned to using as-needed albuterol, so that by the end of the study Arg Arg patients who had regularly used albuterol had a morning peak expiratory flow 30. 5 +/- 12.1 L/min lower (p = 0.012) than Arg/Arg patients who had used albuterol on an as needed basis. There was no decline in peak flow with regular use of albuterol in patients who were homozygous for glycine at beta(2)-AR-16. Evening peak expiratory flow also declined in the Arg/Arg patients who used albuterol regularly but not in those who used albuterol on an as-needed basis. No significant differences in outcomes between regular and as-needed treatment were associated with polymorphisms at position 27 of the beta(2)-AR. No other differences in asthma outcomes that we investigated occurred in relation to these beta(2)-AR polymorphisms. Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

Appropriate use of inhaled corticosteroid and long-acting beta(2)-adrenergic agonist combination therapy among asthma patients in a US commercially insured population.

PubMed

Ye, Xin; Gutierrez, Benjamin; Zarotsky, Victoria; Nelson, Michael; Blanchette, Christopher M

2009-09-01

To examine health care utilization measures indicating which asthma patients are appropriate for inhaled corticosteroid and long-acting beta(2)-adrenergic agonist (ICS/LABA) therapy and determine whether two ICS/LABA therapies were initiated in accordance with guidelines. A retrospective cohort study of commercially insured asthma patients aged > or =12 years that initiated fluticasone propionate/salmeterol (FSC) or budesonide/formoterol fumarate dihydrate (BFC) combination therapy in 2007 was conducted. Use was considered appropriate if patients met any of the following during a 1-year period before ICS/LABA initiation: ICS or leukotriene receptor antagonist (LTRA) use; an asthma-related emergency department (ED) visit or hospitalization; > or =2 oral corticosteroids (OCS) courses; or > or =6 short-acting beta(2)-adrenergic agonist (SABA) canisters. Multivariate logistic regression was used to assess factors associated with appropriate ICS/LABA use. Certain limitations inherent to the use of claims data for research apply to this study. Of 24,231 patients who initiated ICS/LABA therapy, 993 received BFC and 23,238 received FSC. Among all patients, 37.6% met > or =1 criteria for appropriate use. However, compared with FSC users, BFC users had a significantly higher likelihood of meeting > or =1 of these criteria (odds ratio, 2.01; 95% CI, 1.76-2.30; p < 0.001), and a higher proportion of BFC than FSC patients met 4 of the 5 appropriate use criteria. In total, 58.4% of BFC patients versus 36.7% of FSC patients met > or =1 criteria for appropriate use. Other factors associated with appropriate use included age, region, Charlson comorbidity score, number of medications, and prescriber specialty. Fewer than half of all patients fulfilled the specified criteria for being appropriate for ICS/LABA therapy. However, a significantly higher proportion of BFC than FSC users met the criteria for appropriate use of ICS/LABA therapy. These results may suggest a need for improved physician awareness of consensus guidelines for the initiation of ICS/LABA therapy.

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.

Effect of skin temperature on cutaneous vasodilator response to the β-adrenergic agonist isoproterenol

PubMed Central

Hodges, Gary J.; Johnson, John M.

2015-01-01

The vascular response to local skin cooling is dependent in part on a cold-induced translocation of α2C-receptors and an increased α-adrenoreceptor function. To discover whether β-adrenergic function might contribute, we examined whether β-receptor sensitivity to the β-agonist isoproterenol was affected by local skin temperature. In seven healthy volunteers, skin blood flow was measured from the forearm by laser-Doppler flowmetry and blood pressure was measured by finger photoplethysmography. Data were expressed as cutaneous vascular conductance (CVC; laser-Doppler flux/mean arterial blood pressure). Pharmacological agents were administered via intradermal microdialysis. We prepared four skin sites: one site was maintained at a thermoneutral temperature of 34°C (32 ± 10%CVCmax) one site was heated to 39°C (38 ± 11%CVCmax); and two sites were cooled, one to 29°C (22 ± 7%CVCmax) and the other 24°C (16 ± 4%CVCmax). After 20 min at these temperatures to allow stabilization of skin blood flow, isoproterenol was perfused in concentrations of 10, 30, 100, and 300 μM. Each concentration was perfused for 15 min. Relative to the CVC responses to isoproterenol at the thermoneutral skin temperature (34°C) (+21 ± 10%max), low skin temperatures reduced (at 29°C) (+17 ± 6%max) or abolished (at 24°C) (+1 ± 5%max) the vasodilator response, and warm (39°C) skin temperatures enhanced the vasodilator response (+40 ± 9%max) to isoproterenol. These data indicate that β-adrenergic function was influenced by local skin temperature. This finding raises the possibility that a part of the vasoconstrictor response to direct skin cooling could include reduced background β-receptor mediated vasodilation. PMID:25701007

Abnormal norepinephrine clearance and adrenergic receptor sensitivity in idiopathic orthostatic intolerance

NASA Technical Reports Server (NTRS)

Jacob, G.; Shannon, J. R.; Costa, F.; Furlan, R.; Biaggioni, I.; Mosqueda-Garcia, R.; Robertson, R. M.; Robertson, D.

1999-01-01

BACKGROUND: Chronic orthostatic intolerance (OI) is characterized by symptoms of inadequate cerebral perfusion with standing, in the absence of significant orthostatic hypotension. A heart rate increase of >/=30 bpm is typical. Possible underlying pathophysiologies include hypovolemia, partial dysautonomia, or a primary hyperadrenergic state. We tested the hypothesis that patients with OI have functional abnormalities in autonomic neurons regulating cardiovascular responses. METHODS AND RESULTS: Thirteen patients with chronic OI and 10 control subjects underwent a battery of autonomic tests. Systemic norepinephrine (NE) kinetics were determined with the patients supine and standing before and after tyramine administration. In addition, baroreflex sensitivity, hemodynamic responses to bolus injections of adrenergic agonists, and intrinsic heart rate were determined. Resting supine NE spillover and clearance were similar in both groups. With standing, patients had a greater decrease in NE clearance than control subjects (55+/-5% versus 30+/-7%, P<0.02). After tyramine, NE spillover did not change significantly in patients but increased 50+/-10% in control subjects (P<0.001). The dose of isoproterenol required to increase heart rate 25 bpm was lower in patients than in control subjects (0.5+/-0.05 versus 1.0+/-0.1 microg, P<0.005), and the dose of phenylephrine required to increase systolic blood pressure 25 mm Hg was lower in patients than control subjects (105+/-11 versus 210+/-12 microg, P<0.001). Baroreflex sensitivity was lower in patients (12+/-1 versus 18+/-2 ms/mm Hg, P<0.02), but the intrinsic heart rate was similar in both groups. CONCLUSIONS: The decreased NE clearance with standing, resistance to the NE-releasing effect of tyramine, and increased sensitivity to adrenergic agonists demonstrate dramatically disordered sympathetic cardiovascular regulation in patients with chronic OI.

Effect of skin temperature on cutaneous vasodilator response to the β-adrenergic agonist isoproterenol.

PubMed

Hodges, Gary J; Kellogg, Dean L; Johnson, John M

2015-04-01

The vascular response to local skin cooling is dependent in part on a cold-induced translocation of α2C-receptors and an increased α-adrenoreceptor function. To discover whether β-adrenergic function might contribute, we examined whether β-receptor sensitivity to the β-agonist isoproterenol was affected by local skin temperature. In seven healthy volunteers, skin blood flow was measured from the forearm by laser-Doppler flowmetry and blood pressure was measured by finger photoplethysmography. Data were expressed as cutaneous vascular conductance (CVC; laser-Doppler flux/mean arterial blood pressure). Pharmacological agents were administered via intradermal microdialysis. We prepared four skin sites: one site was maintained at a thermoneutral temperature of 34°C (32 ± 10%CVCmax) one site was heated to 39°C (38 ± 11%CVCmax); and two sites were cooled, one to 29°C (22 ± 7%CVCmax) and the other 24°C (16 ± 4%CVCmax). After 20 min at these temperatures to allow stabilization of skin blood flow, isoproterenol was perfused in concentrations of 10, 30, 100, and 300 μM. Each concentration was perfused for 15 min. Relative to the CVC responses to isoproterenol at the thermoneutral skin temperature (34°C) (+21 ± 10%max), low skin temperatures reduced (at 29°C) (+17 ± 6%max) or abolished (at 24°C) (+1 ± 5%max) the vasodilator response, and warm (39°C) skin temperatures enhanced the vasodilator response (+40 ± 9%max) to isoproterenol. These data indicate that β-adrenergic function was influenced by local skin temperature. This finding raises the possibility that a part of the vasoconstrictor response to direct skin cooling could include reduced background β-receptor mediated vasodilation. Copyright © 2015 the American Physiological Society.

Epinephrine and the metabolic syndrome.

PubMed

Ziegler, Michael G; Elayan, Hamzeh; Milic, Milos; Sun, Ping; Gharaibeh, Munir

2012-02-01

Epinephrine is the prototypical stress hormone. Its stimulation of all α and β adrenergic receptors elicits short-term systolic hypertension, hyperglycemia, and other aspects of the metabolic syndrome. Acute epinephrine infusion increases cardiac output and induces insulin resistance, but removal of the adrenal medulla has no consistent effect on blood pressure. Epinephrine is the most effective endogenous agonist at the β2 receptor. Transgenic mice that cannot make epinephrine and mice that lack the β2 receptor become hypertensive during exercise, presumably owing to the absence of β2-mediated vasodilatation. Epinephrine-deficient mice also have cardiac remodeling and poor cardiac responses to stress, but do not develop resting hypertension. Mice that cannot make epinephrine have a normal metabolism on a regular 14% fat diet but become hyperglycemic and insulin resistant when they eat a high fat diet. Vigorous exercise prevents diabetes in young mice and humans that overeat. However, exercise is a less effective treatment in older type 2 human diabetics and had no effect on glucose or insulin responses in older, diabetic mice. Sensitivity of the β2 receptor falls sharply with advancing age, and adrenal epinephrine release also decreases. However, treatment of older diabetic mice with a β2 adrenergic agonist improved insulin sensitivity, indicating that β2 subsensitivity can be overcome pharmacologically. Recent studies show that over the long term, epinephrine prevents hypertension during stress and improves glucose tolerance. The hyperglycemic influence of epinephrine is short-lived. Chronic administration of epinephrine and other β2 agonists improves cellular glucose uptake and metabolism. Overall, epinephrine counteracts the metabolic syndrome.

Segmental arterial mediolysis--an iatrogenic vascular disorder induced by ractopamine.

PubMed

Slavin, Richard E; Yaeger, Micheal J

2012-01-01

Segmental arterial mediolysis, an uncommon arterial disorder most often occurring in the splanchnic muscular arteries of the abdomen, is a cause of catastrophic hemorrhages. Its histology and initial clinical presentations suggested that it represented a localized norepinephrine-induced vasospastic response to perturbations in vascular tone and blood volume distribution caused by coexisting vasoconstrictor conditions. However, later presentations were at odds with some aspects of this hypothesis. Nine greyhound dogs were administered a single dose of ractopamine. Two dogs developing persistent conduction abnormalities with biochemical evidence of heart injury were euthanized and necropsied--one 4 days and the other 17 days after dosage This report is based on findings and comparisons of the canine abdominal and coronary arteries to segmental arterial mediolysis. Lesions having features of early-injurious-stage segmental arterial mediolysis were identified in the canine arteries 4 days postractopamine, and arteries examined after 17 days showed alterations typically occurring in reparative-stage segmental arterial mediolysis. It is suspected that ractopamine, a Beta-2 adrenergic agonist, created segmental arterial mediolysis by neuromodulating the peripheral sympathetic nervous system to release norepinephrine from varicosities of efferent nerves serving splanchnic arteries that stimulate alpha-1 receptors to induce injury at the adventitial medial junction and medial muscle apoptosis. This finding and other cited examples suggest that segmental arterial mediolysis may be a disorder principally caused by iatrogenic or accidental exposure to alpha-1 adrenergic receptor agonists or Beta-2 agonists able to release norepinephrine from the peripheral nervous system. Copyright © 2012 Elsevier Inc. All rights reserved.

β2-adrenergic receptor-mediated negative regulation of group 2 innate lymphoid cell responses.

PubMed

Moriyama, Saya; Brestoff, Jonathan R; Flamar, Anne-Laure; Moeller, Jesper B; Klose, Christoph S N; Rankin, Lucille C; Yudanin, Naomi A; Monticelli, Laurel A; Putzel, Gregory Garbès; Rodewald, Hans-Reimer; Artis, David

2018-03-02

The type 2 inflammatory response is induced by various environmental and infectious stimuli. Although recent studies identified group 2 innate lymphoid cells (ILC2s) as potent sources of type 2 cytokines, the molecular pathways controlling ILC2 responses are incompletely defined. Here we demonstrate that murine ILC2s express the β 2 -adrenergic receptor (β 2 AR) and colocalize with adrenergic neurons in the intestine. β 2 AR deficiency resulted in exaggerated ILC2 responses and type 2 inflammation in intestinal and lung tissues. Conversely, β 2 AR agonist treatment was associated with impaired ILC2 responses and reduced inflammation in vivo. Mechanistically, we demonstrate that the β 2 AR pathway is a cell-intrinsic negative regulator of ILC2 responses through inhibition of cell proliferation and effector function. Collectively, these data provide the first evidence of a neuronal-derived regulatory circuit that limits ILC2-dependent type 2 inflammation. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

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.

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

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

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.

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.

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

Final report of APMP.QM-S6: clenbuterol in porcine meat

NASA Astrophysics Data System (ADS)

Sin, D. W.-M.; Ho, C.; Yip, Y.-C.

2016-01-01

At the CCQM Organic Analysis Working Group (OAWG) Meeting held in April 2012 and the APMP TCQM Meeting held in November 2012, an APMP supplementary comparison (APMP.QM-S6) on the determination of clenbuterol in porcine meat was supported by the OAWG and APMP TCQM. This comparison was organized by the Government Laboratory, Hong Kong. In order to accommodate a wider participation, a pilot study (APMP.QM-P22) was run in parallel to APMP.QM-S6. This study provided the means for assessing the measurement capabilities for determination of low-polarity measurands in a procedure that requires extraction, clean-up, analytical separation, and selective detection in a food matrix. A total of 7 institutes registered for the supplementary comparison and 6 of them submitted their results. 4 results were included for SCRV calculation. All participating laboratories applied Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry (ID-LCMS/MS) technique with clenbuterol-d9 as internal standard spiked for quantitation in this programme. KEY WORDS FOR SEARCH APMP.QM-S6 and Clenbuterol Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The Use of Modafinil in Operational Settings: Individual Difference Implications

DTIC Science & Technology

2000-03-01

them "skylark". On another treatment of narcolepsia and idiopathic hypersomnia . hand, some people are eveningness type, they have the The wakening...showed that modafinil acts as idiopathic hypersomnia and narcolepsy with modafinil. an agonist of ct1-adrenergic post-synaptic receptors (4). Prog...of During sustained operations (SUSOPS) it is impossible narcolepsia and idiopatic hypersomnia . It is synthetized for the soldier to sleep, sometimes

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

PubMed

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

2016-11-22

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

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.

Computational Study on the Different Ligands Induced Conformation Change of β2 Adrenergic Receptor-Gs Protein Complex

PubMed Central

Bai, Qifeng; Zhang, Yang; Ban, Yihe; Liu, Huanxiang; Yao, Xiaojun

2013-01-01

β2 adrenergic receptor (β2AR) regulated many key physiological processes by activation of a heterotrimeric GTP binding protein (Gs protein). This process could be modulated by different types of ligands. But the details about this modulation process were still not depicted. Here, we performed molecular dynamics (MD) simulations on the structures of β2AR-Gs protein in complex with different types of ligands. The simulation results demonstrated that the agonist BI-167107 could form hydrogen bonds with Ser2035.42, Ser2075.46 and Asn2936.55 more than the inverse agonist ICI 118,551. The different binding modes of ligands further affected the conformation of β2AR. The energy landscape profiled the energy contour map of the stable and dissociated conformation of Gαs and Gβγ when different types of ligands bound to β2AR. It also showed the minimum energy pathway about the conformational change of Gαs and Gβγ along the reaction coordinates. By using interactive essential dynamics analysis, we found that Gαs and Gβγ domain of Gs protein had the tendency to separate when the inverse agonist ICI 118,551 bound to β2AR. The α5-helix had a relatively quick movement with respect to transmembrane segments of β2AR when the inverse agonist ICI 118,551 bound to β2AR. Besides, the analysis of the centroid distance of Gαs and Gβγ showed that the Gαs was separated from Gβγ during the MD simulations. Our results not only could provide details about the different types of ligands that induced conformational change of β2AR and Gs protein, but also supplied more information for different efficacies of drug design of β2AR. PMID:23922653

Molecular interactions between fenoterol stereoisomers and derivatives and the β₂-adrenergic receptor binding site studied by docking and molecular dynamics simulations.

PubMed

Plazinska, Anita; Kolinski, Michal; Wainer, Irving W; Jozwiak, Krzysztof

2013-11-01

The β2 adrenergic receptor (β2-AR) has become a model system for studying the ligand recognition process and mechanism of the G protein coupled receptors activation. In the present study stereoisomers of fenoterol and some of its derivatives (N = 94 molecules) were used as molecular probes to identify differences in stereo-recognition interactions between β2-AR and structurally similar agonists. The present study aimed at determining the 3D molecular models of the fenoterol derivative-β2-AR complexes. Molecular models of β2-AR have been developed by using the crystal structure of the human β2-AR T4 lysozyme fusion protein with bound (S)-carazolol (PDB ID: 2RH1) and more recently reported structure of a nanobody-stabilized active state of the β2-AR with the bound full agonist BI-167107 (PDB ID: 3P0G). The docking procedure allowed us to study the similarities and differences in the recognition binding site(s) for tested ligands. The agonist molecules occupied the same binding region, between TM III, TM V, TM VI and TM VII. The residues identified by us during docking procedure (Ser203, Ser207, Asp113, Lys305, Asn312, Tyr308, Asp192) were experimentally indicated in functional and biophysical studies as being very important for the agonist-receptor interactions. Moreover, the additional space, an extension of the orthosteric pocket, was identified and described. Furthermore, the molecular dynamics simulations were used to study the molecular mechanism of interaction between ligands ((R,R')- and (S,S')-fenoterol) and β2-AR. Our research offers new insights into the ligand stereoselective interaction with one of the most important GPCR member. This study may also facilitate the design of improved selective medications, which can be used to treat, prevent and control heart failure symptoms.

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.

Alpha-2 adrenergic activity of bromocriptine and quinpirole in chicken pineal gland. Effects on melatonin synthesis and ( sup 3 H)rauwolscine binding

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

Zawilska, J.; Iuvone, P.M.

In the pineal gland and retina of chickens, serotonin N-acetyl-transferase (NAT) activity and melatonin content are modulated by different receptors, alpha-2 adrenergic receptors in pineal gland and D2-dopamine receptors in retina. The effect of two D2-dopamine receptor agonists, bromocriptine and quinpirole (LY 171555), on melatonin synthesis in these tissues was investigated. Systemic administrations of bromocriptine and quinpirole decreased nocturnal NAT activity and melatonin content of both pineal gland and retina. Bromocriptine was equipotent in the two tissues, whereas quinpirole was approximately 100-fold more potent in retina than in pineal gland. In pineal gland, the suppressive effects of bromocriptine and quinpirolemore » on NAT activity were blocked by yohimbine, a selective alpha-2 adrenergic receptor antagonist, but not by spiperone, a D2-dopamine receptor antagonist. In contrast, bromocriptine- and quinpirole-induced decreases of the enzyme activity in retina were antagonized by spiperone, and not affected by yohimbine. The nocturnal increase of NAT activity of pineal glands in vitro was inhibited with an order of potency clonidine greater than bromocriptine greater than quinpirole. Additionally, bromocriptine and quinpirole displaced the specific binding of (3H)rauwolscine, an alpha-2 adrenergic receptor antagonist, to membranes from chicken pineal gland, with potencies comparable to those observed for inhibition of NAT activity in vitro. It is suggested that bromocriptine and quinpirole, in addition to their D2-dopaminergic activity, can stimulate alpha-2 adrenergic receptors in pineal gland of chicken.« less

Neural control of blood flow during exercise in human metabolic syndrome.

PubMed

Limberg, Jacqueline K; Morgan, Barbara J; Sebranek, Joshua J; Proctor, Lester T; Eldridge, Marlowe W; Schrage, William G

2014-09-01

α-Adrenergic-mediated vasoconstriction is greater during simulated exercise in animal models of metabolic syndrome (MetSyn) when compared with control animals. In an attempt to translate such findings to humans, we hypothesized that adults with MetSyn (n = 14, 35 ± 3 years old) would exhibit greater α-adrenergic responsiveness during exercise when compared with age-matched healthy control subjects (n = 16, 31 ± 3 years old). We measured muscle sympathetic nerve activity (MSNA; microneurography) and forearm blood flow (Doppler ultrasound) during dynamic forearm exercise (15% of maximal voluntary contraction). α-Adrenergic agonists (phenylephrine and clonidine) and an antagonist (phentolamine) were infused intra-arterially to assess α-adrenergic receptor responsiveness and restraint, respectively. Resting MSNA was ∼35% higher in adults with MetSyn (P < 0.05), but did not change in either group with dynamic exercise. Clonidine-mediated vasoconstriction was greater in adults with MetSyn (P < 0.01). Group differences in vascular responses to phenylephrine and phentolamine were not detected (P > 0.05). Interestingly, exercise-mediated vasodilatation was greater in MetSyn (P < 0.05). Adults with MetSyn exhibit greater resting MSNA and clonidine-mediated vasoconstriction, yet preserved functional sympatholysis and higher exercise blood flow during low-intensity hand-grip exercise when compared with age-matched healthy control subjects. These results suggest that adults with MetSyn exhibit compensatory vascular control mechanisms capable of preserving blood flow responses to exercise in the face of augmented sympathetic adrenergic activity. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

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

Provocative tests of parathyroid and C cell function in adrenalectomized and chemically sympathectomized rats.

PubMed

Heath, H

1980-10-01

Recent in vitro and in vivo evidence shows that secretion of parathyroid hormone (PTH) and calcitonin (CT) is stimulated by beta-adrenergic agonists and inhibited by beta-adrenergic antagonists. To assess the possible roles of adrenal medullary or adrenergic nerve terminal catecholamines in calcium homeostasis, we have examined serum calcium (Ca), immunoreactive PTH (iPTH), and immunoreactive CT (iCT) in control, adrenalectomized (ADRX), and chemically sympathectomized [6-hydroxydopamine (6-OHDA)] rats. Animals were studied in the fed and fasted states, after ip injection of CA and after ip injection of EDTA. In comparison with fasted rats, fed control rats tended to have increased serum Ca and iCT, but decreased or unchanged iPTH. Neither adrenalectomy nor 6-OHDA treatment notably altered this pattern. Serum iCT concentrations rose markedly after ip Ca, and peak iCT responses remained normal in ADRX and 6-OHDA-treated rats. Similarly, rises of iPTH levels after EDTA-induced hypocalcemia were normal in ADRX and 6-OHDA-treated rats. The only possible abnormality concerned basal serum iCT levels after 6-OHDA treatment, which were lower than control in five of six experiments, albeit not always significantly. We conclude that deprivation of either adrenal medullary or adrenergic nerve terminal catecholamines does not interfere with plasma Ca regulation or the homeostatic responses of PTH and CT in the rat.

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.

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

An improved clenbuterol detection by immunochromatographic assay with bacteria@Au composite as signal amplifier.

PubMed

Huang, Qiong; Bu, Tong; Zhang, Wentao; Yan, Lingzhi; Zhang, Mengyue; Yang, Qingfeng; Huang, Lunjie; Yang, Baowei; Hu, Na; Suo, Yourui; Wang, Jianlong; Zhang, Daohong

2018-10-01

Immunochromatographic assays (ICAs) are most frequently used for on-site rapid screening of clenbuterol. To improve sensitivity, a novel probe with bacteria as signal carriers was developed. Bacteria can load a great deal of gold nanoparticles (AuNPs) on their surface, meaning much fewer antibodies are needed to produce clearly visible results, although low concentrations of antibody could also trigger fierce competition between free analyte and the immobilized antigen. Thus, a limited number of antibodies was key to significantly improved sensitivity. Analytical conditions, including bacterial species, coupling method, and concentration, were optimized. The visual detection limit (VDL) for clenbuterol was 0.1 ng/mL, a 20-fold improvement in sensitivity compared with traditional strips. This work has opened up a new route for signal amplification and improved performance of ICAs. Furthermore, inactivated bacteria could also be environment-friendly and robust signal carriers for other biosensors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Beta agonists in livestock feed: status, health concerns, and international trade.

PubMed

Centner, T J; Alvey, J C; Stelzleni, A M

2014-09-01

Since the U.S. Food and Drug Administration approved ractopamine hydrochloride and zilpaterol hydrochloride in animal feeds, usage of those compounds has been a topic of worldwide debate. Ractopamine and zilpaterol are β-adrenergic agonists used as veterinary drugs to increase weight gain in certain animals raised for food. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established maximum residue limits for ractopamine, which were adopted by the Codex Alimentarius Commission (Codex). No maximum residue limits for zilpaterol have been adopted by JECFA, and new reports of animal mobility issues confront the use of this feed additive. However, many countries disagree with the Codex standards and are restricting or banning meat products containing β agonists. The bans by major importers of U.S. meat products have prompted some to advocate that the United States use the World Trade Organization dispute settlement body. This paper looks at the developments to provide a fuller accounting of what the issues may mean to U.S. firms selling meat products containing residues of β agonists.

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

PEG-coated gold nanoparticles attenuate β-adrenergic receptor-mediated cardiac hypertrophy.

PubMed

Qiao, Yuhui; Zhu, Baoling; Tian, Aiju; Li, Zijian

2017-01-01

Gold nanoparticles (AuNPs) are widely used as a drug delivery vehicle, which can accumulate in the heart through blood circulation. Therefore, it is very important to understand the effect of AuNPs on the heart, especially under pathological conditions. In this study, we found that PEG-coated AuNPs attenuate β-adrenergic receptor (β-AR)-mediated acute cardiac hypertrophy and inflammation. However, both isoproterenol, a non-selective β-AR agonist, and AuNPs did not induce cardiac function change or cardiac fibrosis. AuNPs exerted an anti-cardiac hypertrophy effect by decreasing β 1 -AR expression and its downstream ERK1/2 hypertrophic pathway. Our results indicated that AuNPs might be safe and have the potential to be used as multi-functional materials (drug carrier systems and anti-cardiac hypertrophy agents).

Comparative molecular field analysis of fenoterol derivatives: A platform towards highly selective and effective beta(2)-adrenergic receptor agonists.

PubMed

Jozwiak, Krzysztof; Woo, Anthony Yiu-Ho; Tanga, Mary J; Toll, Lawrence; Jimenez, Lucita; Kozocas, Joseph A; Plazinska, Anita; Xiao, Rui-Ping; Wainer, Irving W

2010-01-15

To use a previously developed CoMFA model to design a series of new structures of high selectivity and efficacy towards the beta(2)-adrenergic receptor. Out of 21 computationally designed structures 6 compounds were synthesized and characterized for beta(2)-AR binding affinities, subtype selectivities and functional activities. the best compound is (R,R)-4-methoxy-1-naphthylfelnoterol with K(i)beta(2)-AR=0.28microm, K(i)beta(1)-AR/K(i)beta(2)-AR=573, EC(50cAMP)=3.9nm, EC(50cardio)=16nm. The CoMFA model appears to be an effective predictor of the cardiomocyte contractility of the studied compounds which are targeted for use in congestive heart failure. Copyright 2009 Elsevier Ltd. All rights reserved.

Effects of the new imidazopyridine CL 86-02-01 on isolated papillary muscle of guinea-pig hearts.

PubMed

Studenik, C; Lemmens-Gruber, R; Heistracher, P

1998-06-01

Inotropic activity and the effect of CL 86-02-01 (2-(3-methoxy-5-methylsulfinyl-2-thienyl)-1H-imidazo[4,5-c]pyridine hydrochloride, CAS 109 792-24-7) on membrane resting and action potentials were studied in isolated guinea-pig papillary muscles. Membrane resting potential and action potential parameters were not significantly changed, while CL 86-02-01 exerted a concentration-dependent inotropic effect by increasing the maximum rate of force development and maximum rate of force relaxation. Time to peak force, relaxation time and total contraction time were reduced. These effects are similar to those of beta-adrenergic drugs and phosphodiesterase inhibitors, but markedly differ from those described for other positive inotropic agents like cardiac glycosides, calcium agonists, alpha-adrenergic drugs or increased extracellular calcium concentration.

Protection against Acetylcholinesterase Inhibitor Toxicity by Alpha- Adrenergic Agonists

DTIC Science & Technology

1992-10-28

acetvlthiocholine iodide (substrate). and 6.9 mM Dithiosnitrobenzoic acid . The absorbance at 412 nm was recorded for 2 rain. 1~1 RESULTS PART I...however, the drug has been shown to be quite effective in limiting seizure production in the audiogenic 1261 and kainic acid [31 animal models of...acetyicholinesterase inhibitor soman. Neurosci.Ltt. 78: 107-112. 3. Baran, H., Hortnagi, H. and Homykiewicz, 0. (1989). Kainic acid -induced seizures

Thermoregulation: Research and Clinical Applications

DTIC Science & Technology

1989-08-01

phenylephrine (often used as a "selec- tive" a-agonist) show poor selectivity between al- and f-adrenergic receptors in brown fat cells, as judged by the...The fact that these inhibitors of prostaglandin synthesis block a large portion of the increase in body tem- perature due to stress has led us to...analysis was performed using the Mann-Whitney U-test to compare drug treated groups and the appropriate con- trol groups. RESULTS: LPS reduces temperature

Ligand induced change of β2 adrenergic receptor from active to inactive conformation and its implication for the closed/open state of the water channel: insight from molecular dynamics simulation, free energy calculation and Markov state model analysis.

PubMed

Bai, Qifeng; Pérez-Sánchez, Horacio; Zhang, Yang; Shao, Yonghua; Shi, Danfeng; Liu, Huanxiang; Yao, Xiaojun

2014-08-14

The reported crystal structures of β2 adrenergic receptor (β2AR) reveal that the open and closed states of the water channel are correlated with the inactive and active conformations of β2AR. However, more details about the process by which the water channel states are affected by the active to inactive conformational change of β2AR remain illusive. In this work, molecular dynamics simulations are performed to study the dynamical inactive and active conformational change of β2AR induced by inverse agonist ICI 118,551. Markov state model analysis and free energy calculation are employed to explore the open and close states of the water channel. The simulation results show that inverse agonist ICI 118,551 can induce water channel opening during the conformational transition of β2AR. Markov state model (MSM) analysis proves that the energy contour can be divided into seven states. States S1, S2 and S5, which represent the active conformation of β2AR, show that the water channel is in the closed state, while states S4 and S6, which correspond to the intermediate state conformation of β2AR, indicate the water channel opens gradually. State S7, which represents the inactive structure of β2AR, corresponds to the full open state of the water channel. The opening mechanism of the water channel is involved in the ligand-induced conformational change of β2AR. These results can provide useful information for understanding the opening mechanism of the water channel and will be useful for the rational design of potent inverse agonists of β2AR.

Inhibition of beta-adrenergic receptor trafficking in adult cardiocytes by MAP4 decoration of microtubules.

PubMed

Cheng, Guangmao; Qiao, Fei; Gallien, Thomas N; Kuppuswamy, Dhandapani; Cooper, George

2005-03-01

Decreased beta-adrenergic receptor (beta-AR) number occurs both in animal models of cardiac hypertrophy and failure and in patients. beta-AR recycling is an important mechanism for the beta-AR resensitization that maintains a normal complement of cell surface beta-ARs. We have shown that 1) in severe pressure overload cardiac hypertrophy, there is extensive microtubule-associated protein 4 (MAP4) decoration of a dense microtubule network; and 2) MAP4 microtubule decoration inhibits muscarinic acetylcholine receptor recycling in neuroblastoma cells. We asked here whether MAP4 microtubule decoration inhibits beta-AR recycling in adult cardiocytes. [(3)H]CGP-12177 was used as a beta-AR ligand, and feline cardiocytes were isolated and infected with adenovirus containing MAP4 (AdMAP4) or beta-galactosidase (Adbeta-gal) cDNA. MAP4 decorated the microtubules extensively only in AdMAP4 cardiocytes. beta-AR agonist exposure reduced cell surface beta-AR number comparably in AdMAP4 and Adbeta-gal cardiocytes; however, after agonist withdrawal, the cell surface beta-AR number recovered to 78.4 +/- 2.9% of the pretreatment value in Adbeta-gal cardiocytes but only to 56.8 +/- 1.4% in AdMAP4 cardiocytes (P < 0.01). This result was confirmed in cardiocytes isolated from transgenic mice having cardiac-restricted MAP4 overexpression. In functional terms of cAMP generation, beta-AR agonist responsiveness of AdMAP4 cells was 47% less than that of Adbeta-gal cells. We conclude that MAP4 microtubule decoration interferes with beta-AR recycling and that this may be one mechanism for beta-AR downregulation in heart failure.

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)

CNS β3-adrenergic receptor activation regulates feeding behavior, white fat browning, and body weight.

PubMed

Richard, Jennifer E; López-Ferreras, Lorena; Chanclón, Belén; Eerola, Kim; Micallef, Peter; Skibicka, Karolina P; Wernstedt Asterholm, Ingrid

2017-09-01

Pharmacological β 3 -adrenergic receptor (β 3 AR) activation leads to increased mitochondrial biogenesis and activity in white adipose tissue (WAT), a process commonly referred to as "browning", and transiently increased insulin release. These effects are associated with improved metabolic function and weight loss. It is assumed that this impact of β 3 AR agonists is mediated solely through activation of β 3 ARs in adipose tissue. However, β 3 ARs are also found in the brain, in areas such as the brain stem and the hypothalamus, which provide multisynaptic innervation to brown and white adipose depots. Thus, contrary to the current adipocentric view, the central nervous system (CNS) may also have the ability to regulate energy balance and metabolism through actions on central β 3 ARs. Therefore, this study aimed to elucidate whether CNS β 3 ARs can regulate browning of WAT and other aspects of metabolic regulation, such as food intake control and insulin release. We found that acute central injection of β 3 AR agonist potently reduced food intake, body weight, and increased hypothalamic neuronal activity in rats. Acute central β 3 AR stimulation was also accompanied by a transient increase in circulating insulin levels. Moreover, subchronic central β 3 AR agonist treatment led to a browning response in both inguinal (IWAT) and gonadal WAT (GWAT), along with reduced GWAT and increased BAT mass. In high-fat, high-sugar-fed rats, subchronic central β 3 AR stimulation reduced body weight, chow, lard, and sucrose water intake, in addition to increasing browning of IWAT and GWAT. Collectively, our results identify the brain as a new site of action for the anorexic and browning impact of β 3 AR activation. Copyright © 2017 the American Physiological Society.

Increased vascular sensitivity and connexin43 expression after sympathetic denervation.

PubMed

Slovut, David P; Mehta, Shyamal H; Dorrance, Anne M; Brosius, Frank C; Watts, Stephanie W; Webb, R Clinton

2004-05-01

Following denervation, arteries demonstrate a heightened sensitivity to alpha-adrenergic agonists and increased oscillatory contractions that may partly result from increased gap junction expression. Hence, we wanted to study the effect of sympathetic denervation on connexin43 (Cx43) expression and agonist-induced contractility in the vascular smooth muscle (VSM). Effects of denervation with reserpine (3 mg/kg/day, i.p.) or topical 5% phenol-glycerol on VSM contractions and expression of the gap junction Cx43 mRNA by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting for Cx43 protein were examined. Wistar-Kyoto (WKY) rat tail arteries were exposed to norepinephrine (NE) (10(-9)-10(-5) M). Reactivity was also examined in the carotid arteries and thoracic aortas from Cx43 heterozygote deficient (KO) mice. The concentration for NE-induced contraction was lower in reserpine- and phenol-treated vessels than controls (p<0.05). NE-induced oscillatory activity (OA) was seen in 5/5 reserpine- and 5/8 phenol-treated vessels vs. 0/12 controls (p<0.05). Spontaneous OA was observed more frequently in carotid and aortic rings from WT than Cx43 KO rings. Cumulative OA in response to alpha-adrenergic stimulation was significantly greater in WT carotid (429+/-101 vs. 128+/-7 mN s, p<0.05) and aortic rings (337+/-85 vs. 134+/-11 mN s, p<0.05) than in Cx43 KO rings. Following denervation, RT-PCR showed significantly increased levels of Cx43 mRNA (p<0.05). Western blot analysis revealed near doubling of Cx43 protein (p<0.05). We conclude that sympathetic denervation results in increased expression of Cx43, which in turn, contributes to increased spontaneous and agonist-induced OA in VSM.

Stereoselective binding of agonists to the β2-adrenergic receptor: insights into molecular details and thermodynamics from molecular dynamics simulations.

PubMed

Plazinska, Anita; Plazinski, Wojciech

2017-05-02

The β 2 -adrenergic receptor (β 2 -AR) is one of the most studied G-protein-coupled receptors. When interacting with ligand molecules, it exhibits a binding characteristic that is strongly dependent on ligand stereoconfiguration. In particular, many experimental and theoretical studies confirmed that stereoisomers of an important β 2 -AR agonist, fenoterol, are associated with diverse mechanisms of binding and activation of β 2 -AR. The objective of the present study was to explore the stereoselective binding of fenoterol to β 2 -AR through the application of an advanced computational methodology based on enhanced-sampling molecular dynamics simulations and potentials of interactions tailored to investigate the stereorecognition effects. The results remain in very good, quantitative agreement with the experimental data (measured in the context of ligand-receptor affinities and their dependence on the temperature), which provides an additional validation for the applied computational protocols. Additionally, our results contribute to the understanding of stereoselective agonist binding by β 2 -AR. Although the significant role of the N293 6.55 residue is confirmed, we additionally show that stereorecognition does not depend solely on the N293-ligand interactions; the stereoselective effects rely on the co-operation of several residues located on both the 6th and 7th transmembrane domains and on extracellular loops. The magnitude and character of the contributions of these residues may be very diverse and result in either enhancing or reducing the stereoselective effects. The same is true when considering the enthalpic and entropic contributions to the binding free energies, which also are dependent on the ligand stereoconfiguration.

The β3 Adrenergic Receptor Agonist BRL37344 Exacerbates Atrial Structural Remodeling Through iNOS Uncoupling in Canine Models of Atrial Fibrillation.

PubMed

Wang, Xiaobing; Wang, Ruifeng; Liu, Guangzhong; Dong, Jingmei; Zhao, Guanqi; Tian, Jingpu; Sun, Jiayu; Jia, Xiuyue; Wei, Lin; Wang, Yuping; Li, Weimin

2016-01-01

The role of the β3-adrenergic receptor (β3-AR) agonist BRL37344 in atrial fibrillation (AF) structural remodeling and the underlying mechanisms as a therapeutic target were investigated. Four groups of dogs were evaluated: sham, pacing, β3-AR agonist BRL37344 (β3-AGO), and β3-AR antagonist L748337 (β3-ANT) groups. Dogs in the pacing, β3-AGO and β3-ANT groups were subjected to rapid atrial pacing for four weeks. Atrial structure and function, AF inducibility and duration, atrial myocyte apoptosis and interstitial fibrosis were assessed. Atrial superoxide anions were evaluated by fluorescence microscopy and colorimetric assays. Cardiac nitrate+nitrite levels were used to assess nitric oxide (NO) production. Protein and mRNA expression of β3-AR, neuronal NO synthase (nNOS), inducible NO synthase (iNOS), endothelial NO synthase (eNOS) and guanosine triphosphate cyclohydrolase-1 (GCH-1) as well as tetrahydrobiopterin (BH4) levels were measured. β3-AR was up-regulated in AF. Stimulation of β3-AR significantly increased atrial myocyte apoptosis, fibrosis and atrial dilatation, resulting in increased AF induction and prolonged duration. These effects were attenuated by β3-ANT. Moreover, β3-AGO reduced BH4 and NO production and increased superoxide production, which was inhibited by the specific iNOS inhibitor, 1400w β3-AGO also increased iNOS but decreased eNOS and had no effect on nNOS expression in AF. β3-AR stimulation resulted in atrial structural remodeling by increasing iNOS uncoupling and related oxidative stress. β3-AR up-regulation and iNOS uncoupling might be underlying AF therapeutic targets. © 2016 The Author(s) Published by S. Karger AG, Basel.

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

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

Influence of thyroid status on hepatic alpha 1-adrenoreceptor responsiveness.

PubMed

Daza, F J; Parrilla, R; Martín-Requero, A

1997-12-01

The present work aimed to elucidate the influence of thyroid functional status on the alpha 1-adrenoreceptor-induced activation of hepatic metabolic functions. The experiments were performed in either a nonrecirculating liver perfusion system featuring continuous monitoring of portal pressure, PO2, pCa, and pH, or isolated hepatocytes from euthyroid, hyperthyroid, and hypothyroid rats. Hypothyroidism decreased the alpha 1-adrenergic stimulation of respiration, glycogen breakdown, and gluconeogenesis. These effects were accompanied by a decreased intracellular Ca2+ mobilization corroborating that those processes are regulated by the Ca(2+)-dependent branch of the alpha 1-adrenoreceptor signaling pathway. Moreover, in hyperthyroid rats the alpha 1-adrenergic-induced increase in cytosolic Ca2+ was enhanced, and glucose synthesis or mobilization was not altered. The thyroid status influenced neither the alpha 1-adrenergic stimulation of vascular smooth muscle contraction nor the alpha 1-agonist-induced intracellular alkalinization and protein kinase C (PKC) activation. Thus the distinct impairment of the Ca(2+)-dependent branch of the alpha 1-adrenoreceptor signaling pathway by thyroid status provides a useful tool to investigate the role played by each signaling pathway, Ca2+ or PKC, in controlling hepatic functions.

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.

Practitioner Review: Treatments for Tourette syndrome in children and young people - a systematic review.

PubMed

Whittington, Craig; Pennant, Mary; Kendall, Tim; Glazebrook, Cristine; Trayner, Penny; Groom, Madeleine; Hedderly, Tammy; Heyman, Isobel; Jackson, Georgina; Jackson, Stephen; Murphy, Tara; Rickards, Hugh; Robertson, Mary; Stern, Jeremy; Hollis, Chris

2016-09-01

Tourette syndrome (TS) and chronic tic disorder (CTD) affect 1-2% of children and young people, but the most effective treatment is unclear. To establish the current evidence base, we conducted a systematic review of interventions for children and young people. Databases were searched from inception to 1 October 2014 for placebo-controlled trials of pharmacological, behavioural, physical or alternative interventions for tics in children and young people with TS or CTD. Certainty in the evidence was assessed with the GRADE approach. Forty trials were included [pharmacological (32), behavioural (5), physical (2), dietary (1)]. For tics/global score there was evidence favouring the intervention from four trials of α2-adrenergic receptor agonists [clonidine and guanfacine, standardised mean difference (SMD) = -0.71; 95% CI -1.03, -0.40; N = 164] and two trials of habit reversal training (HRT)/comprehensive behavioural intervention (CBIT) (SMD = -0.64; 95% CI -0.99, -0.29; N = 133). Certainty in the effect estimates was moderate. A post hoc analysis combining oral clonidine/guanfacine trials with a clonidine patch trial continued to demonstrate benefit (SMD = -0.54; 95% CI -0.92, -0.16), but statistical heterogeneity was high. Evidence from four trials suggested that antipsychotic drugs improved tic scores (SMD = -0.74; 95% CI -1.08, -0.40; N = 76), but certainty in the effect estimate was low. The evidence for other interventions was categorised as low or very low quality, or showed no conclusive benefit. When medication is considered appropriate for the treatment of tics, the balance of clinical benefits to harm favours α2-adrenergic receptor agonists (clonidine and guanfacine) as first-line agents. Antipsychotics are likely to be useful but carry the risk of harm and so should be reserved for when α2-adrenergic receptor agonists are either ineffective or poorly tolerated. There is evidence that HRT/CBIT is effective, but there is no evidence for HRT/CBIT alone relative to combining medication and HRT/CBIT. There is currently no evidence to suggest that the physical and dietary interventions reviewed are sufficiently effective and safe to be considered as treatments. © 2016 Association for Child and Adolescent Mental Health.

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

Dissociation between cardiomyocyte function and remodeling with beta-adrenergic receptor blockade in isolated canine mitral regurgitation.

PubMed

Pat, Betty; Killingsworth, Cheryl; Denney, Thomas; Zheng, Junying; Powell, Pamela; Tillson, Michael; Dillon, A Ray; Dell'Italia, Louis J

2008-12-01

The low-pressure volume overload of isolated mitral regurgitation (MR) is associated with increased adrenergic drive, left ventricular (LV) dilatation, and loss of interstitial collagen. We tested the hypothesis that beta1-adrenergic receptor blockade (beta1-RB) would attenuate LV remodeling after 4 mo of MR in the dog. beta1-RB did not attenuate collagen loss or the increase in LV mass in MR dogs. Using MRI and three-dimensional (3-D) analysis, there was a 70% increase in the LV end-diastolic (LVED) volume-to-LV mass ratio, a 23% decrease in LVED midwall circumferential curvature, and a >50% increase in LVED 3-D radius/wall thickness in MR dogs that was not attenuated by beta1-RB. However, beta1-RB caused a significant increase in LVED length from the base to apex compared with untreated MR dogs. This was associated with an increase in isolated cardiomyocyte length (171+/-5 microm, P<0.05) compared with normal (156+/-3 microm) and MR (165+/-4 microm) dogs. Isolated cardiomyocyte fractional shortening was significantly depressed in MR dogs compared with normal dogs (3.73+/-0.31 vs. 5.02+/-0.26%, P<0.05) and normalized with beta1-RB (4.73+/-0.48%). In addition, stimulation with the beta-adrenergic receptor agonist isoproterenol (25 nM) increased cardiomyocyte fractional shortening by 215% (P<0.05) in beta1-RB dogs compared with normal (56%) and MR (50%) dogs. In summary, beta1-RB improved LV cardiomyocyte function and beta-adrenergic receptor responsiveness despite further cell elongation. The failure to attenuate LV remodeling associated with MR could be due to a failure to improve ultrastructural changes in extracellular matrix organization.

A meta-analysis of the effects of β-adrenergic blockers in chronic heart failure.

PubMed

Zhang, Xiaojian; Shen, Chengwu; Zhai, Shujun; Liu, Yukun; Yue, Wen-Wei; Han, Li

2016-10-01

Adrenergic β-blockers are drugs that bind to, but do not activate β-adrenergic receptors. Instead they block the actions of β-adrenergic agonists and are used for the treatment of various diseases such as cardiac arrhythmias, angina pectoris, myocardial infarction, hypertension, headache, migraines, stress, anxiety, prostate cancer, and heart failure. Several meta-analysis studies have shown that β-blockers improve the heart function and reduce the risks of cardiovascular events, rate of mortality, and sudden death through chronic heart failure (CHF) of patients. The present study identified results from recent meta-analyses of β-adrenergic blockers and their usefulness in CHF. Databases including Medline/Embase/Cochrane Central Register of Controlled Trials (CENTRAL), and PubMed were searched for the periods May, 1985 to March, 2011 and June, 2013 to August, 2015, and a number of studies identified. Results of those studies showed that use of β-blockers was associated with decreased sudden cardiac death in patients with heart failure. However, contradictory results have also been reported. The present meta-analysis aimed to determine the efficacy of β-blockers on mortality and morbidity in patients with heart failure. The results showed that mortality was significantly reduced by β-blocker treatment prior to the surgery of heart failure patients. The results from the meta-analysis studies showed that β-blocker treatment in heart failure patients correlated with a significant decrease in long-term mortality, even in patients that meet one or more exclusion criteria of the MERIT-HF study. In summary, the findings of the current meta-analysis revealed beneficial effects different β-blockers have on patients with heart failure or related heart disease.

A meta-analysis of the effects of β-adrenergic blockers in chronic heart failure

PubMed Central

Zhang, Xiaojian; Shen, Chengwu; Zhai, Shujun; Liu, Yukun; Yue, Wen-Wei; Han, Li

2016-01-01

Adrenergic β-blockers are drugs that bind to, but do not activate β-adrenergic receptors. Instead they block the actions of β-adrenergic agonists and are used for the treatment of various diseases such as cardiac arrhythmias, angina pectoris, myocardial infarction, hypertension, headache, migraines, stress, anxiety, prostate cancer, and heart failure. Several meta-analysis studies have shown that β-blockers improve the heart function and reduce the risks of cardiovascular events, rate of mortality, and sudden death through chronic heart failure (CHF) of patients. The present study identified results from recent meta-analyses of β-adrenergic blockers and their usefulness in CHF. Databases including Medline/Embase/Cochrane Central Register of Controlled Trials (CENTRAL), and PubMed were searched for the periods May, 1985 to March, 2011 and June, 2013 to August, 2015, and a number of studies identified. Results of those studies showed that use of β-blockers was associated with decreased sudden cardiac death in patients with heart failure. However, contradictory results have also been reported. The present meta-analysis aimed to determine the efficacy of β-blockers on mortality and morbidity in patients with heart failure. The results showed that mortality was significantly reduced by β-blocker treatment prior to the surgery of heart failure patients. The results from the meta-analysis studies showed that β-blocker treatment in heart failure patients correlated with a significant decrease in long-term mortality, even in patients that meet one or more exclusion criteria of the MERIT-HF study. In summary, the findings of the current meta-analysis revealed beneficial effects different β-blockers have on patients with heart failure or related heart disease. PMID:27703506

Structure of a nanobody-stabilized active state of the β(2) adrenoceptor.

PubMed

Rasmussen, Søren G F; Choi, Hee-Jung; Fung, Juan Jose; Pardon, Els; Casarosa, Paola; Chae, Pil Seok; Devree, Brian T; Rosenbaum, Daniel M; Thian, Foon Sun; Kobilka, Tong Sun; Schnapp, Andreas; Konetzki, Ingo; Sunahara, Roger K; Gellman, Samuel H; Pautsch, Alexander; Steyaert, Jan; Weis, William I; Kobilka, Brian K

2011-01-13

G protein coupled receptors (GPCRs) exhibit a spectrum of functional behaviours in response to natural and synthetic ligands. Recent crystal structures provide insights into inactive states of several GPCRs. Efforts to obtain an agonist-bound active-state GPCR structure have proven difficult due to the inherent instability of this state in the absence of a G protein. We generated a camelid antibody fragment (nanobody) to the human β(2) adrenergic receptor (β(2)AR) that exhibits G protein-like behaviour, and obtained an agonist-bound, active-state crystal structure of the receptor-nanobody complex. Comparison with the inactive β(2)AR structure reveals subtle changes in the binding pocket; however, these small changes are associated with an 11 Å outward movement of the cytoplasmic end of transmembrane segment 6, and rearrangements of transmembrane segments 5 and 7 that are remarkably similar to those observed in opsin, an active form of rhodopsin. This structure provides insights into the process of agonist binding and activation.

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.

Fetal nicotine exposure produces postnatal up-regulation of adenylate cyclase activity in peripheral tissues

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

Slotkin, T.A.; Navarro, H.A.; McCook, E.C.

1990-01-01

Gestational exposure to nicotine has been shown to affect development of noradrenergic activity in both the central and peripheral nervous systems. In the current study, pregnant rats received nicotine infusions of 6 mg/kg/day throughout gestation, administered by osmotic minipump implants. After birth, offspring of the nicotine-infused dams exhibited marked increases in basal adenylate cyclase activity in membranes prepared from kidney and heart, as well as supersensitivity to stimulation by either a {beta}-adrenergic agonist, isoproterenol, or by forskolin. The altered responses were not accompanied by up-regulation of {beta}-adrenergic receptors: in fact, ({sup 125}I)pindolol binding was significantly decreased in the nicotine group.more » These results indicate that fetal nicotine exposure affects enzymes involved in membrane receptor signal transduction, leading to altered responsiveness independently of changes at the receptor level.« less

CL 316, 243 mediated reductions in blood glucose are enhanced in RIP140{sup −/−} mice independent of alterations in lipolysis

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

Peppler, Willem T.; Miotto, Paula M.; Holloway, Graham P.

The β-3 adrenergic agonist CL 316, 243 acutely lowers blood glucose through a mechanism thought to involve fatty-acid induced insulin release. The purpose of this study was to determine if ablation of the nuclear receptor, receptor-inactivating protein 140 (RIP140), altered this response. Here, we used a single injection of CL 316, 243 (1 mg/kg) and found that whole body RIP140{sup −/−} mice had a greater decline in blood glucose over 2 h. This occurred alongside increased hexokinase II (HKII) protein content in adipose tissue and skeletal muscle, but independent of changes in circulating insulin or indices of lipolysis. These data indicate thatmore » RIP140 has a unique role in the acute effect of β-3 adrenergic receptor activation using CL 316, 243.« less

The management of the acute ischemic priapism: A state of the art review.

PubMed

Falcone, M; Gillo, A; Capece, M; Raheem, A; Ralph, D; Garaffa, G

2017-12-01

To review the current literature on early penile prosthesis implantation in patients with refractory ischemic priapism (IP). A systematic search for the terms "penile prosthesis", "priapism", "impotence", "fibrosis", "downsized prosthesis cylinders", and "patient satisfaction" has been carried out in PubMed, EMBASE, Cochrane, SCOPUS and Science Citation Index databases. Cavernosal tissue damage in IP is time related. Conservative measures and aspiration with or without intracorporeal instillation of α-adrenergic agonists are usually successful in the early stages. Shunt surgery in patients remains debatable, as the lack of response to aspiration and instillation of α-adrenergic agonists indicates that irreversible changes in the cavernosal smooth muscle are likely to have already occurred. Immediate penile prosthesis implantation in patients with refractory IP settles the priapic episode, maintains the long term rigidity necessary to engage in penetrative sexual intercourse and prevents the otherwise inevitable penile shortening. Although complication rates after penile prosthesis implantation in acute priapism are higher than in virgin cases, they are still lower than after implantation in patients with severe corporal fibrosis due to chronic priapism. Regardless of the complication rates, penile prosthesis implantation in refractory IP should be preferred as it allows the preservation of penile length, which is one of the main factors influencing postoperative patient's satisfaction following surgery. Copyright © 2017 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

Beta2-adrenergic agonist use and the risk of multiple sclerosis: a total population-based case-control study.

PubMed

Tsai, Ching-Piao; Lin, Feng-Cheng; Lee, Charles Tzu-Chi

2014-10-01

The aim of this study was to investigate whether the use of fenoterol, a beta2-adrenergic agonist, was associated with multiple sclerosis (MS) risk by conducting a total population-based case-control study in Taiwan. A total of 578 patients with newly diagnosed MS who had a severely disabling disease (SDD) certificate between January 1, 2002 and December 1, 2008 comprised the case group. These cases were compared with 2890 gender-, age-, residence-, and insurance premium-matched controls. Fenoterol use was analyzed using a conditional logistic regression model that controlled for asthma, chronic obstructive pulmonary disease (COPD), salbutamol and steroid use. Compared with the group of people who did not use fenoterol, the adjusted odds ratios were 0.67 (95% confidence interval (CI) = 0.48-0.93, p = 0.016) for the group prescribed fenoterol below 2.25 cumulative defined daily dose (cDDD) and 0.49 (95% CI = 0.33-0.71, p < 0.001) for the group with a cumulative fenoterol use of more than 2.25 cDDD. The dose-response relationship was similar within the non-asthma patients. The associations were similar between males and females, but differences between age groups were observed. The results of this study suggest that fenoterol use may reduce the risk of MS. © The Author(s), 2014.

β3-adrenergic receptor activation induces TGFβ1 expression in cardiomyocytes via the PKG/JNK/c-Jun pathway.

PubMed

Xu, Zhongcheng; Wu, Jimin; Xin, Junzhou; Feng, Yenan; Hu, Guomin; Shen, Jing; Li, Mingzhe; Zhang, Youyi; Xiao, Han; Wang, Li

2018-06-05

In heart failure, the expression of cardiac β 3 -adrenergic receptors (β 3 -ARs) increases. However, the precise role of β 3 -AR signaling within cardiomyocytes remains unclear. Transforming growth factor β1 (TGFβ1) is a crucial cytokine mediating the cardiac remodeling that plays a causal role in the progression of heart failure. Here, we set out to determine the effect of β 3 -AR activation on TGFβ1 expression in rat cardiomyocytes and examine the underlying mechanism. The selective β 3 -AR agonist BRL37344 induced an increase in TGFβ1 expression and the phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun in β 3 -AR-overexpressing cardiomyocytes. Those effects of BRL37344 were suppressed by a β 3 -AR antagonist. Moreover, the inhibition of JNK and c-Jun activity by a JNK inhibitor and c-Jun siRNA blocked the increase in TGFβ1 expression upon β 3 -AR activation. A protein kinase G (PKG) inhibitor also attenuated β 3 -AR-agonist-induced TGFβ1 expression and the phosphorylation of JNK and c-Jun. In conclusion, the β 3 -AR activation in cardiomyocytes increases the expression of TGFβ1 via the PKG/JNK/c-Jun pathway. These results help us further understand the role of β 3 -AR signaling in heart failure. Copyright © 2018 Elsevier Inc. All rights reserved.

β-Adrenergic modulation of cancer cell proliferation: available evidence and clinical perspectives.

PubMed

Coelho, Marisa; Soares-Silva, Cátia; Brandão, Daniela; Marino, Franca; Cosentino, Marco; Ribeiro, Laura

2017-02-01

In this review, we aimed to present and discuss the available preclinical and epidemiological evidences regarding the modulation of cancer cell proliferation by β-adrenoceptors (β-AR), with a specific focus on the putative effects of β-blockers according to their pharmacological properties. A comprehensive review of the published literature was conducted, and the evidences concerning the involvement of β-AR in cancer as well as the possible role of β-blockers were selected and discussed. The majority of reviewed studies show that: (1) All the cancer types express both β1- and β2-AR, with the exception of neuroblastoma only seeming to express β2-AR; (2) adrenergic agonists are able to increase proliferation of several types of cancers; (3) the proliferative effect seems to be mediated by both β1- and β2-AR; (4) binding to β-AR results in a cAMP transient flux which activates two major downstream effector systems: protein kinase A and EPAC and (5) β-blockers might be putative adjuvants for cancer treatment. Overall, the reviewed studies show strong evidences that β-AR activation, through several intracellular mechanisms, modulate tumor cell proliferation suggesting β-blockers can be a feasible therapeutic approach to antagonize β-adrenergic response or have a protective effect per se. This review highlight the need for intensifying the research not only on the molecular mechanisms underlying the β-adrenergic influence in cancer, but also on the implications of biased agonism of β-blockers as potential antitumor agents.

Effects of muscarinic, alpha-adrenergic, and substance P agonists and ionomycin on ion transport mechanisms in the rat parotid acinar cell. The dependence of ion transport on intracellular calcium

PubMed Central

1989-01-01

The relationship between receptor-mediated increases in the intracellular free calcium concentration [( Ca]i) and the stimulation of ion fluxes involved in fluid secretion was examined in the rat parotid acinar cell. Agonist-induced increases in [Ca]i caused the rapid net loss of up to 50-60% of the total content of intracellular chloride (Cli) and potassium (Ki), which is consistent with the activation of calcium-sensitive chloride and potassium channels. These ion movements were accompanied by a 25% reduction in the intracellular volume. The relative magnitudes of the losses of Ki and the net potassium fluxes promoted by carbachol (a muscarinic agonist), phenylephrine (an alpha-adrenergic agonist), and substance P were very similar to their characteristic effects on elevating [Ca]i. Carbachol stimulated the loss of Ki through multiple efflux pathways, including the large-conductance Ca-activated K channel. Carbachol and substance P increased the levels of intracellular sodium (Nai) to more than 2.5 times the normal level by stimulating the net uptake of sodium through multiple pathways; Na-K-2Cl cotransport accounted for greater than 50% of the influx, and approximately 20% was via Na-H exchange, which led to a net alkalinization of the cells. Ionomycin stimulated similar fluxes through these two pathways, but also promoted sodium influx through an additional pathway which was nearly equivalent in magnitude to the combined uptake through the other two pathways. The carbachol- induced increase in Nai and decrease in Ki stimulated the activity of the sodium pump, measured by the ouabain-sensitive rate of oxygen consumption, to nearly maximal levels. In the absence of extracellular calcium or in cells loaded with the calcium chelator BAPTA (bis[o- aminophenoxy]ethane-N,N,N',N'-tetraacetic acid) the magnitudes of agonist- or ionomycin-stimulated ion fluxes were greatly reduced. The parotid cells displayed a marked desensitization to substance P; within 10 min the elevation of [Ca]i and alterations in Ki, Nai, and cell volume spontaneously returned to near baseline levels. In addition to quantitating the activation of various ion flux pathways in the rat parotid acinar cell, these results demonstrate that the activation of ion transport systems responsible for fluid secretion in this tissue is closely linked to the elevation of [Ca]i. PMID:2467962

Mapping Genetic Variants Associated with Beta-Adrenergic Responses in Inbred Mice

PubMed Central

Hersch, Micha; Peter, Bastian; Kang, Hyun Min; Schüpfer, Fanny; Abriel, Hugues; Pedrazzini, Thierry; Eskin, Eleazar; Beckmann, Jacques S.

2012-01-01

β-blockers and β-agonists are primarily used to treat cardiovascular diseases. Inter-individual variability in response to both drug classes is well recognized, yet the identity and relative contribution of the genetic players involved are poorly understood. This work is the first genome-wide association study (GWAS) addressing the values and susceptibility of cardiovascular-related traits to a selective β 1-blocker, Atenolol (ate), and a β-agonist, Isoproterenol (iso). The phenotypic dataset consisted of 27 highly heritable traits, each measured across 22 inbred mouse strains and four pharmacological conditions. The genotypic panel comprised 79922 informative SNPs of the mouse HapMap resource. Associations were mapped by Efficient Mixed Model Association (EMMA), a method that corrects for the population structure and genetic relatedness of the various strains. A total of 205 separate genome-wide scans were analyzed. The most significant hits include three candidate loci related to cardiac and body weight, three loci for electrocardiographic (ECG) values, two loci for the susceptibility of atrial weight index to iso, four loci for the susceptibility of systolic blood pressure (SBP) to perturbations of the β-adrenergic system, and one locus for the responsiveness of QTc (p<10−8). An additional 60 loci were suggestive for one or the other of the 27 traits, while 46 others were suggestive for one or the other drug effects (p<10−6). Most hits tagged unexpected regions, yet at least two loci for the susceptibility of SBP to β-adrenergic drugs pointed at members of the hypothalamic-pituitary-thyroid axis. Loci for cardiac-related traits were preferentially enriched in genes expressed in the heart, while 23% of the testable loci were replicated with datasets of the Mouse Phenome Database (MPD). Altogether these data and validation tests indicate that the mapped loci are relevant to the traits and responses studied. PMID:22859963

Beta 2 adrenergic receptor gene restriction fragment length polymorphism and bronchial asthma.

PubMed Central

Ohe, M.; Munakata, M.; Hizawa, N.; Itoh, A.; Doi, I.; Yamaguchi, E.; Homma, Y.; Kawakami, Y.

1995-01-01

BACKGROUND--Beta 2 adrenergic dysfunction may be one of the underlying mechanisms responsible for atopy and bronchial asthma. The gene encoding the human beta 2 adrenergic receptor (beta 2ADR) has recently been isolated and sequenced. In addition, a two allele polymorphism of this receptor gene has been identified in white people. A study was carried out to determine whether this polymorphism is functionally important and has any relation to airways responsiveness, atopy, or asthma. METHODS--The subjects studied were 58 family members of four patients with atopic asthma. Restriction fragment length polymorphism (RFLP) with Ban-I digestion of the beta 2ADR gene was detected by a specific DNA probe with Southern blot analysis. Airways responses to inhaled methacholine and the beta 2 agonist salbutamol, the skin prick test, and serum IgE levels were also examined and correlated to the beta 2ADR gene RFLP. In addition, measurements of cAMP responses to isoproterenol in peripheral mononuclear cells were performed in 22 healthy subjects whose genotype for beta 2ADR was known. RESULTS--A two allele polymorphism (2.3 kb and 2.1 kb) of the beta 2ADR gene was detected in the Japanese population. Family members without allele 2.3 kb (homozygote of allele 2.1 kb) had lower airways responses to inhaled salbutamol than those with allele 2.3 kb. The incidence of asthma was higher in those without allele 2.3 kb than in those with allele 2.3 kb. The beta 2ADR gene RFLP had no relation to airways responses to methacholine and atopic status. cAMP responses in peripheral mononuclear cells of the subjects without allele 2.3 kb tended to be lower than those of the subjects with allele 2.3 kb. CONCLUSIONS--These results suggest that Ban-I RFLP of the beta 2ADR gene may have some association with the airways responses to beta 2 agonists and the incidence of bronchial asthma. Images PMID:7785006

miR-132 and miR-212 are increased in pancreatic cancer and target the retinoblastoma tumor suppressor

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

Park, Jong-Kook; Henry, Jon C.; Jiang, Jinmai

2011-03-25

Research highlights: {yields} The expression of miR-132 and miR-212 are significantly increased in pancreatic cancer. {yields} miR-132 and miR-212 target the tumor suppressor pRb, resulting in enhanced proliferation. {yields} miR-132 and miR-212 expression is increased by a {beta}2 adrenergic receptor agonist, suggesting a novel mechanism for pancreatic cancer progression. -- Abstract: Numerous microRNAs (miRNAs) are reported as differentially expressed in cancer, however the consequence of miRNA deregulation in cancer is unknown for many miRNAs. We report that two miRNAs located on chromosome 17p13, miR-132 and miR-212, are over-expressed in pancreatic adenocarcinoma (PDAC) tissues. Both miRNAs are predicted to target themore » retinoblastoma tumor suppressor, Rb1. Validation of this interaction was confirmed by luciferase reporter assay and western blot in a pancreatic cancer cell line transfected with pre-miR-212 and pre-miR-132 oligos. Cell proliferation was enhanced in Panc-1 cells transfected with pre-miR-132/-212 oligos. Conversely, antisense oligos to miR-132/-212 reduced cell proliferation and caused a G{sub 2}/M cell cycle arrest. The mRNA of a number of E2F transcriptional targets were increased in cells over expressing miR-132/-212. Exposing Panc-1 cells to the {beta}2 adrenergic receptor agonist, terbutaline, increased the miR-132 and miR-212 expression by 2- to 4-fold. We report that over-expression of miR-132 and miR-212 result in reduced pRb protein in pancreatic cancer cells and that the increase in cell proliferation from over-expression of these miRNAs is likely due to increased expression of several E2F target genes. The {beta}2 adrenergic pathway may play an important role in this novel mechanism.« less

Modulation of postjunctional α-adrenergic vasoconstriction during exercise and exogenous ATP infusions in ageing humans

PubMed Central

Kirby, Brett S; Crecelius, Anne R; Voyles, Wyatt F; Dinenno, Frank A

2011-01-01

Abstract The ability to modulate sympathetic α-adrenergic vasoconstriction in contracting muscle is impaired with age. In young adults, adenosine triphosphate (ATP) has been shown to blunt sympathetic vasoconstrictor responsiveness similar to exercise. Therefore, we tested the hypothesis that modulation of postjunctional α-adrenergic vasoconstriction to exogenous ATP is impaired in ageing humans. We measured forearm blood flow (FBF; Doppler ultrasound) and calculated vascular conductance (FVC) to intra-arterial infusions of phenylephrine (α1-agonist) and dexmedetomidine (α2-agonist) during rhythmic handgrip exercise (15% MVC), a control non-exercise vasodilator condition (adenosine), and ATP infusion in seven older (64 ± 3 years) and seven young (22 ± 1 years) healthy adults. Forearm hyperaemia was matched across all vasodilatating conditions. During adenosine, forearm vasoconstrictor responses to direct α1-stimulation were lower in older compared with young adults (ΔFVC =−25 ± 3%vs.−41 ± 5%; P < 0.05), whereas the responses to α2-stimulation were not different (−35 ± 6%vs.−44 ± 8%; NS). During exercise, α1-mediated vasoconstriction was significantly blunted compared with adenosine in both young (−9 ± 2%vs.−41 ± 5%) and older adults (−15 ± 2%vs.−25 ± 3%); however, the magnitude of sympatholysis was reduced in older adults (32 ± 13 vs. 74 ± 8%; P < 0.05). Similarly, α2-mediated vasoconstriction during exercise was significantly blunted in both young (−15 ± 4%vs.−44 ± 8%) and older adults (−26 ± 3%vs.−35 ± 6%), however the magnitude of sympatholysis was reduced in older adults (19 ± 8%vs. 60 ± 10%; P < 0.05). During ATP, both α1- and α2-mediated vasoconstriction was nearly abolished in young and older adults (ΔFVC ∼−5%), and the magnitude of sympatholysis was similar in both age groups (∼85–90%). Our findings indicate that the ability to modulate postjunctional α-adrenergic vasoconstriction during exercise is impaired with age, whereas the sympatholytic effect of exogenous ATP is preserved. Thus, if impairments in vascular control during exercise in older adults involve vasoactive ATP, we speculate that circulating ATP is reduced with advancing age. PMID:21486772

[Beta-1 adrenoceptor blockade decreases the firing rate to painful stimuli in spinal wide-dynamic range neurons in rats].

PubMed

Lamothe-Molina, Paul J; Lamothe-Molina, Pedro A; López-Ávila, Alberto

2014-01-01

It is known that epinephrine/norepinephrine inhibit acute pain transmission. However, the role of ß-adrenoceptors is not clear. Thus, we analyzed if beta-1 and/or beta-2 adrenoceptors can modulate acute pain transmission by performing in vivo single unit recordings during painful and non-painful peripheral stimulation in rats. Longitudinal study in which we analyzed seven groups of male rats Wistar: control group (n = 11): saline (0.9 %); EPI group (n = 8): epinephrine 100 mcg; beta-1 agonist group (n = 8): dobutamine 125 mcg; beta-1-antagonist group (n = 9): metoprolol 100 mcg; beta-2-agonist group (n = 7): clenbuterol 100 mcg; beta-2-antagonist group (n = 8): butoxamine 100 mcg; beta-1-antagonist + EPI group (n = 10): metoprolol 100 mcg + epinephrine 100 mcg. For the statistical analysis we used ANOVA. Epinephrine significantly reduced the basal firing rate (BFR) in 34.1 % (p < 0.05) and also the evoked response by painful stimulation in 56 % (p < 0.05). No change was observed in the evoked response by non-painful stimulation. ANTß1 was the only beta-adrenoceptor acting drug that significantly reduced the evoked response by painful stimulation in 41 % (p < 0.05). None of the other drugs alone affected either the BFR or the evoked response to non-painful or painful stimulation. It is the first time that a beta-1-adrenoceptor antagonist (metoprolol) probes to be effective in reducing the response to painful stimulation in WDR neurons.

Genetically encoded pH sensor for tracking surface proteins through endocytosis.

PubMed

Grover, Anmol; Schmidt, Brigitte F; Salter, Russell D; Watkins, Simon C; Waggoner, Alan S; Bruchez, Marcel P

2012-05-14

Traffic cam: a tandem dye prepared from a FRET acceptor and a fluorogenic donor functions as a cell surface ratiometric pH indicator, which upon internalization serves to follow protein trafficking during endocytosis. This sensor was used to analyze agonist-dependent internalization of β(2)-adrenergic receptors. It was also used as a surrogate antigen to reveal direct surface-to-endosome antigen transfer between dendritic cells (not shown). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Respiratory failure and lethal hypotension due to blue-ringed octopus and tetrodotoxin envenomation observed and counteracted in animal models.

PubMed

Flachsenberger, W A

The effects of crude blue-ringed octopus venom gland extract and tetrodotoxin (TTX) on anaesthetised rats and rabbits were studied. Paralysis of the respiratory musculature causing anoxia and cyanosis was overcome with positive, artificial respiration. The second lethal mechanism of the toxins: rapid and severe hypotension, had to be counteracted peripherally, since neural transmission had been drastically reduced by the toxins. Noradrenaline, d-amphetamine, phenylephrine and methoxamine, agonists acting on vascular adrenergic a-receptors, were tested.

Cannabinoid receptor activation correlates with the proapoptotic action of the β2-adrenergic agonist (R,R')-4-methoxy-1-naphthylfenoterol in HepG2 hepatocarcinoma cells.

PubMed

Paul, Rajib K; Ramamoorthy, Anuradha; Scheers, Jade; Wersto, Robert P; Toll, Lawrence; Jimenez, Lucita; Bernier, Michel; Wainer, Irving W

2012-10-01

Inhibition of cell proliferation by fenoterol and fenoterol derivatives in 1321N1 astrocytoma cells is consistent with β(2)-adrenergic receptor (β(2)-AR) stimulation. However, the events that result in fenoterol-mediated control of cell proliferation in other cell types are not clear. Here, we compare the effect of the β(2)-AR agonists (R,R')-fenoterol (Fen) and (R,R')-4-methoxy-1-naphthylfenoterol (MNF) on signaling and cell proliferation in HepG2 hepatocarcinoma cells by using Western blotting and [(3)H]thymidine incorporation assays. Despite the expression of β(2)-AR, no cAMP accumulation was observed when cells were stimulated with isoproterenol or Fen, although the treatment elicited both mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt activation. Unexpectedly, isoproterenol and Fen promoted HepG2 cell growth, but MNF reduced proliferation together with increased apoptosis. The mitogenic responses of Fen were attenuated by 3-(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol (ICI 118,551), a β(2)-AR antagonist, whereas those of MNF were unaffected. Because of the coexpression of β(2)-AR and cannabinoid receptors (CBRs) and their impact on HepG2 cell proliferation, these Gα(i)/Gα(o)-linked receptors may be implicated in MNF signaling. Cell treatment with (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-napthalenylmethanone (WIN 55,212-2), a synthetic agonist of CB(1)R and CB(2)R, led to growth inhibition, whereas inverse agonists of these receptors blocked MNF mitogenic responses without affecting Fen signaling. MNF responses were sensitive to pertussis toxin. The β(2)-AR-deficient U87MG cells were refractory to Fen, but responsive to the antiproliferative actions of MNF and WIN 55,212-2. The data indicate that the presence of the naphthyl moiety in MNF results in functional coupling to the CBR pathway, providing one of the first examples of a dually acting β(2)-AR-CBR ligand.

Cannabinoid Receptor Activation Correlates with the Proapoptotic Action of the β2-Adrenergic Agonist (R,R′)-4-Methoxy-1-Naphthylfenoterol in HepG2 Hepatocarcinoma CellsS⃞

PubMed Central

Paul, Rajib K.; Ramamoorthy, Anuradha; Scheers, Jade; Wersto, Robert P.; Toll, Lawrence; Jimenez, Lucita; Wainer, Irving W.

2012-01-01

Inhibition of cell proliferation by fenoterol and fenoterol derivatives in 1321N1 astrocytoma cells is consistent with β2-adrenergic receptor (β2-AR) stimulation. However, the events that result in fenoterol-mediated control of cell proliferation in other cell types are not clear. Here, we compare the effect of the β2-AR agonists (R,R′)-fenoterol (Fen) and (R,R′)-4-methoxy-1-naphthylfenoterol (MNF) on signaling and cell proliferation in HepG2 hepatocarcinoma cells by using Western blotting and [3H]thymidine incorporation assays. Despite the expression of β2-AR, no cAMP accumulation was observed when cells were stimulated with isoproterenol or Fen, although the treatment elicited both mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt activation. Unexpectedly, isoproterenol and Fen promoted HepG2 cell growth, but MNF reduced proliferation together with increased apoptosis. The mitogenic responses of Fen were attenuated by 3-(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol (ICI 118,551), a β2-AR antagonist, whereas those of MNF were unaffected. Because of the coexpression of β2-AR and cannabinoid receptors (CBRs) and their impact on HepG2 cell proliferation, these Gαi/Gαo-linked receptors may be implicated in MNF signaling. Cell treatment with (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-napthalenylmethanone (WIN 55,212-2), a synthetic agonist of CB1R and CB2R, led to growth inhibition, whereas inverse agonists of these receptors blocked MNF mitogenic responses without affecting Fen signaling. MNF responses were sensitive to pertussis toxin. The β2-AR-deficient U87MG cells were refractory to Fen, but responsive to the antiproliferative actions of MNF and WIN 55,212-2. The data indicate that the presence of the naphthyl moiety in MNF results in functional coupling to the CBR pathway, providing one of the first examples of a dually acting β2-AR-CBR ligand. PMID:22776956

The role of nitric oxide synthase in reduced vasocontractile responsiveness induced by prolonged α1-adrenergic receptor stimulation in rat thoracic aorta

PubMed Central

Gürdal, Hakan; Can, Alp; Uğur, Mehmet

2005-01-01

Prolonged exposure (6–12 h) of rat aorta to alpha1-adrenergic receptor (α1AR) agonist phenylephrine (Phe) leads to a decrease in α1AR-mediated vasoconstriction. This reduced responsiveness to α1AR stimulation was strongly dependent on the intactness of the endothelium. We examined the effect of Phe on nitric oxide synthase (NOS) activity by measuring the conversion of [3H]L-arginine to [3H]L-citrulline in rat aorta or in endothelial cells isolated from rat aorta. Phe stimulation increased NOS activity in control aortas. This response was antagonized by prazosin. However, Phe increased neither the activity of NOS nor intracellular Ca2+ in the isolated endothelial cells from the control aortas, whereas acetylcholine (Ach) was able to stimulate both responses in these cells. This result suggests that Phe stimulates α1AR on vascular smooth muscle cells and has an indirect influence on endothelial cells to increase NOS activity. In Phe-exposed aortic rings, basal NOS activity was found to have increased compared to vehicle-exposed control rings. Stimulation with Phe or Ach caused a small increase over basal NOS activity in these preparations. Prolonged exposure to Phe also caused an enhancement of Ach-mediated vasorelaxation in rat aorta. Immunoblot and reverse transcription–polymerase chain reaction experiments showed that prolonged exposure of rat aorta to Phe resulted in an increased expression of eNOS, but not iNOS. This increase was antagonized by nonselective antagonist prazosin. Immunohistochemical staining experiments also showed that expression of eNOS increased in endothelial cells after Phe exposure of the aortas. These results, all together, showed that prolonged exposure of rat aorta to α1AR agonist Phe enhanced the expression of eNOS and basal NOS activity, which probably causes a decreased vasocontractile response to Phe or to other agonists such as 5HT (5-hydroxytryptamine) in rat aorta. This phenomenon can be considered more as a functional antagonism of vasocontractile response to agonists mediated by endothelium than a specific desensitization of α1AR-mediated signalling in vascular smooth muscle cells. PMID:15753950

Acute orexigenic effect of agmatine involves interaction between central α2-adrenergic and GABAergic receptors.

PubMed

Taksande, Brijesh Gulabrao; Sharma, Omi; Aglawe, Manish Manohar; Kale, Mayur Bhimrao; Gawande, Dinesh Yugraj; Umekar, Milind Janraoji; Kotagale, Nandkishor Ramdas

2017-09-01

Agmatine and GABA have been abundantly expressed in brain nuclei involved in regulation of energy homeostasis and promoting stimulation of food intake in rodents. However, their mutual interaction, if any, in the elicitation of feeding behavior is largely remains unclear. The current study provides experimental evidence for the possible interaction of agmatine, adrenergic and GABAergic systems in stimulation of feeding in satiated rats. Satiated rats fitted with intracerebroventricular (i.c.v.) cannulae and were administered agmatine, alone or jointly with (a) GABA A receptor agonist, muscimol, diazepam or antagonist bicuculline and flumazenil, GABA A positive modulator, allopregnanolone or negative modulator of GABA A receptor, dehydroepiandrosterone (b) In view of the high affinity of agmatine for α 2 -adrenoceptors and the close association between α 2 -adrenoceptors and GABAergic system, the effect of their modulators on feeding elicited by agmatine/GABAergic agonists were also examined. I.c.v. administration of agmatine (40-80μg/rat) induces the significant orexigenic effect in satiated rats. The orexigenic effect of agmatine was potentiated by muscimol (25ng/rat, i.c.v.); diazepam (0.5mg/kg, i.p.); allopregnanolone (0.5mg/kg, s.c.) and blocked by bicuculline (1mg/kg, i.p.) and dehydroepiandrosterone (4mg/kg,s.c.). However, it remained unaffected in presence of flumazenil (25ng/rat, i.c.v.). The orexigenic effect of agmatine and GABAergic agonists was potentiated by a α 2 -adrenoceptors agonist, clonidine (10ng/rat, i.c.v.) and blocked by its antagonist, yohimbine (5μg/rat, i.c.v.). Yohimbine also blocked the hyperphagic effect elicited by ineffective dose combination of agmatine (5μg/rat, i.c.v.) with muscimol (25ng/rat, i.c.v.) or diazepam (0.5mg/kg, i.p.) or allopregnanolone (0.5mg/kg,s.c.). The results of the present study suggest that agmatine induced α 2 -adrenoceptors activation might facilitate GABAergic activity to stimulate food intake in satiated rats. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

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

Oil Exposure Impairs In Situ Cardiac Function in Response to β-Adrenergic Stimulation in Cobia (Rachycentron canadum).

PubMed

Cox, Georgina K; Crossley, Dane A; Stieglitz, John D; Heuer, Rachael M; Benetti, Daniel D; Grosell, Martin

2017-12-19

Aqueous crude oil spills expose fish to varying concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs), which can have lethal and sublethal effects. The heart is particularly vulnerable in early life stages, as PAH toxicity causes developmental cardiac abnormalities and impaired cardiovascular function. However, cardiac responses of juvenile and adult fish to acute oil exposure remain poorly understood. We sought to assess cardiac function in a pelagic fish species, the cobia (Rachycentron canadum), following acute (24 h) exposure to two ecologically relevant levels of dissolved PAHs. Cardiac power output (CPO) was used to quantify cardiovascular performance using an in situ heart preparation. Cardiovascular performance was varied using multiple concentrations of the β-adrenoceptor agonist isoproterenol (ISO) and by varying afterload pressures. Oil exposure adversely affected CPO with control fish achieving maximum CPO's (4 mW g -1 Mv) greater than that of oil-exposed fish (1 mW g -1 Mv) at ISO concentrations of 1 × 10 -6 M. However, the highest concentration of ISO (1 × 10 -5 M) rescued cardiac function. This indicates an interactive effect between oil-exposure and β-adrenergic stimulation and suggests if animals achieve very large increases in β-adrenergic stimulation it could play a compensatory role that may mitigate some adverse effects of oil-exposure in vivo.

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

NASA Technical Reports Server (NTRS)

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

1998-01-01

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

Berberine-induced pigment dispersion in Bufo melanostictus melanophores by stimulation of beta-2 adrenergic receptors.

PubMed

Ali, Sharique A; Naaz, Ishrat; Choudhary, Ram Kumar

2014-02-01

Reduced production of melanin by decreased or the absence of melanocytes leads to various hypopigmentation disorders, and the development of melanogenetic agents for photoprotection and hypopigmentation disorders is one of the top priority areas of research. Hence, the present study was carried out to elucidate the ability of berberine, a principal active ingredient present in the roots of the herb Berberis vulgaris to stimulate pigment dispersion in the isolated skin melanophores of the toad Bufo melanostictus. In the present study, mean melanophore size index of the isolated skin melanophores of B. melanostictus was assayed after treating with various concentrations of berberine. A marked melanin dispersion response leading to skin darkening was observed in the isolated melanophores of toad in response to berberine, which was found to be mediated through beta-2 adrenergic receptors. The physiologically significant dose-related melanin dispersion effects of berberine per se were found to be completely abolished by propranolol, which is a specific beta-2 adrenergic receptor blocker. These per se melanin dispersal effects were also found to be markedly potentiated by isoprenaline, which is a specific beta-adrenoceptor agonist. The results indicate that berberine causes a tremendous, dose-dependent, physiologically significant pigment dispersing in the isolated skin melanophores of B. melanostictus.

The surging role of Chromogranin A in cardiovascular homeostasis

NASA Astrophysics Data System (ADS)

Tota, Bruno; Angelone, Tommaso; Cerra, Maria

2014-08-01

Together with Chromogranin B and Secretogranins, Chromogranin A (CGA) is stored in secretory (chromaffin) granules of the diffuse neuroendocrine system and released with noradrenalin and adrenalin. Co-stored within the granule together with neuropeptideY, cardiac natriuretic peptide hormones, several prohormones and their proteolytic enzymes, CGA is a multifunctional protein and a major marker of the sympatho-adrenal neuroendocrine activity. Due to its partial processing to several biologically active peptides, CGA appears an important pro-hormone implicated in relevant modulatory actions on endocrine, cardiovascular, metabolic, and immune systems through both direct and indirect sympatho-adrenergic interactions. As a part of this scenario, we here illustrate the emerging role exerted by the full-length CGA and its three derived fragments, i.e. Vasostatin 1, catestatin and serpinin, in the control of circulatory homeostasis with particular emphasis on their cardio-vascular actions under both physiological and physio-pathological conditions. The Vasostatin 1- and catestatin-induced cardiodepressive influences are achieved through anti-beta-adrenergic-NO-cGMP signalling, while serpinin acts like beta1-adrenergic agonist through AD-cAMP-independent NO signalling. On the whole, these actions contribute to wide our knowledge regarding the sympatho-chromaffin control of the cardiovascular system and its highly integrated “whip-brake” networks.

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

Thermodynamics and docking of agonists to the β(2)-adrenoceptor determined using [(3)H](R,R')-4-methoxyfenoterol as the marker ligand.

PubMed

Toll, Lawrence; Pajak, Karolina; Plazinska, Anita; Jozwiak, Krzysztof; Jimenez, Lucita; Kozocas, Joseph A; Tanga, Mary J; Bupp, James E; Wainer, Irving W

2012-06-01

G protein-coupled receptors (GPCRs) are integral membrane proteins that change conformation after ligand binding so that they can transduce signals from an extracellular ligand to a variety of intracellular components. The detailed interaction of a molecule with a G protein-coupled receptor is a complicated process that is influenced by the receptor conformation, thermodynamics, and ligand conformation and stereoisomeric configuration. To better understand the molecular interactions of fenoterol analogs with the β(2)-adrenergic receptor, we developed a new agonist radioligand for binding assays. [(3)H](R,R')-methoxyfenoterol was used to probe the binding affinity for a series of fenoterol stereoisomers and derivatives. The results suggest that the radioligand binds with high affinity to an agonist conformation of the receptor, which represents approximately 25% of the total β(2)-adrenoceptor (AR) population as determined with the antagonist [(3)H]CGP-12177. The β(2)-AR agonists tested in this study have considerably higher affinity for the agonist conformation of the receptor, and K(i) values determined for fenoterol analogs model much better the cAMP activity of the β(2)-AR elicited by these ligands. The thermodynamics of binding are also different when interacting with an agonist conformation, being purely entropy-driven for each fenoterol isomer, rather than a mixture of entropy and enthalpy when the fenoterol isomers binding was determined using [(3)H]CGP-12177. Finally, computational modeling identified the molecular interactions involved in agonist binding and allow for the prediction of additional novel β(2)-AR agonists. The study underlines the possibility of using defined radioligand structure to probe a specific conformation of such shape-shifting system as the β(2)-adrenoceptor.

Thermodynamics and Docking of Agonists to the β2-Adrenoceptor Determined Using [3H](R,R′)-4-Methoxyfenoterol as the Marker Ligand

PubMed Central

Pajak, Karolina; Plazinska, Anita; Jozwiak, Krzysztof; Jimenez, Lucita; Kozocas, Joseph A.; Tanga, Mary J.; Bupp, James E.; Wainer, Irving W.

2012-01-01

G protein-coupled receptors (GPCRs) are integral membrane proteins that change conformation after ligand binding so that they can transduce signals from an extracellular ligand to a variety of intracellular components. The detailed interaction of a molecule with a G protein-coupled receptor is a complicated process that is influenced by the receptor conformation, thermodynamics, and ligand conformation and stereoisomeric configuration. To better understand the molecular interactions of fenoterol analogs with the β2-adrenergic receptor, we developed a new agonist radioligand for binding assays. [3H](R,R′)-methoxyfenoterol was used to probe the binding affinity for a series of fenoterol stereoisomers and derivatives. The results suggest that the radioligand binds with high affinity to an agonist conformation of the receptor, which represents approximately 25% of the total β2-adrenoceptor (AR) population as determined with the antagonist [3H]CGP-12177. The β2-AR agonists tested in this study have considerably higher affinity for the agonist conformation of the receptor, and Ki values determined for fenoterol analogs model much better the cAMP activity of the β2-AR elicited by these ligands. The thermodynamics of binding are also different when interacting with an agonist conformation, being purely entropy-driven for each fenoterol isomer, rather than a mixture of entropy and enthalpy when the fenoterol isomers binding was determined using [3H]CGP-12177. Finally, computational modeling identified the molecular interactions involved in agonist binding and allow for the prediction of additional novel β2-AR agonists. The study underlines the possibility of using defined radioligand structure to probe a specific conformation of such shape-shifting system as the β2-adrenoceptor. PMID:22434858

Rapid Determination of Clenbuterol in Pork by Direct Immersion Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry.

PubMed

Ye, Diru; Wu, Susu; Xu, Jianqiao; Jiang, Ruifen; Zhu, Fang; Ouyang, Gangfeng

2016-02-01

Direct immersion solid-phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was developed for rapid analysis of clenbuterol in pork for the first time. In this work, a low-cost homemade 44 µm polydimethylsiloxane (PDMS) SPME fiber was employed to extract clenbuterol in pork. After extraction, derivatization was performed by suspending the fiber in the headspace of the 2 mL sample vial saturated with a vapor of 100 µL hexamethyldisilazane. Lastly, the fiber was directly introduced to GC-MS for analysis. All parameters that influenced absorption (extraction time), derivatization (derivatization reagent, time and temperature) and desorption (desorption time) were optimized. Under optimized conditions, the method offered a wide linear range (10-1000 ng g(-1)) and a low detection limit (3.6 ng g(-1)). Finally, the method was successfully applied in the analysis of pork from the market, and recoveries of the method for spiked pork were 97.4-105.7%. Compared with the traditional solvent extraction method, the proposed method was much cheaper and fast. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Non-adrenergic vasoconstriction and vasodilatation of guinea-pig aorta by β-phenylethylamine and amphetamine - Role of nitric oxide determined with L-NAME and NO scavengers.

PubMed

Broadley, Kenneth J; Broadley, Harrison D

2018-01-05

Sympathomimetic and trace amines, including β-phenylethylamine (PEA) and amphetamine, increase blood pressure and constrict isolated blood vessels. By convention this is regarded as a sympathomimetic response, however, recent studies suggest trace amine-associated receptor (TAAR) involvement. There is also uncertainty whether these amines also release nitric oxide (NO) causing opposing vasodilatation. These questions were addressed in guinea-pig isolated aorta, a species not previously examined. Guinea-pig aortic rings were set up to measure contractile tension. Cumulative concentration-response curves were constructed for the reference α-adrenoceptor agonist, phenylephrine, PEA or d-amphetamine before and in the presence of vehicles, the α 1 -adrenoceptor antagonist, prazosin (1µM), the nitric oxide synthase inhibitor, N ω -nitro-L-arginine (L-NAME), or NO scavengers, curcumin and astaxanthin. Prazosin inhibited phenylephrine contractions with low affinity consistent with α 1L -adrenoceptors. However, PEA and amphetamine were not antagonised, indicating non-adrenergic responses probably via TAARs. L-NAME potentiated contractions to PEA both in the absence and presence of prazosin, indicating that PEA releases NO to cause underlying opposing vasodilatation, independent of α 1 -adrenoceptors. L-NAME also potentiated amphetamine and phenylephrine. PEA was potentiated by the NO scavenger astaxanthin but less effectively. Curcumin, an active component of turmeric, however, inhibited PEA. Trace amines therefore constrict blood vessels non-adrenergically with an underlying NO-mediated non-adrenergic vasodilatation. This has implications in the pressor actions of these amines when NO is compromised. Copyright © 2017 Elsevier B.V. All rights reserved.

Beta(3)-adrenergic signaling acutely down regulates adipose triglyceride lipase in brown adipocytes.

PubMed

Deiuliis, Jeffrey A; Liu, Li-Fen; Belury, Martha A; Rim, Jong S; Shin, Sangsu; Lee, Kichoon

2010-06-01

Mice exposed to cold rely upon brown adipose tissue (BAT)-mediated nonshivering thermogenesis to generate body heat using dietary glucose and lipids from the liver and white adipose tissue. In this report, we investigate how cold exposure affects the PI3 K/Akt signaling cascade and the expression of genes involved in lipid metabolism and trafficking in BAT. Cold exposure at an early time point led to the activation of the PI3 K/Akt, insulin-like signaling cascade followed by a transient decrease in adipose triglyceride lipase (ATGL) gene and protein expression in BAT. To further investigate how cold exposure-induced signaling altered ATGL expression, cultured primary brown adipocytes were treated with the beta(3)-adrenergic receptor (beta(3)AR) agonist CL 316,243 (CL) resulting in activation of PI3 K/Akt, ERK 1/2, and p38 signaling pathways and significantly decreased ATGL protein levels. ATGL protein levels decreased significantly 30 min post CL treatment suggesting protein degradation. Inhibition of PKA signaling by H89 rescued ATGL levels. The effects of PKA signaling on ATGL were shown to be independent of relevant pathways downstream of PKA such as PI3 K/Akt, ERK 1/2, and p38. However, CL treatment in 3T3-L1 adipocytes did not decrease ATGL protein and mRNA expression, suggesting a distinct response in WAT to beta3-adrenergic agonism. Transitory effects, possibly attributed to acute Akt activation during the early recruitment phase, were noted as well as stable changes in gene expression which may be attributed to beta3-adrenergic signaling in BAT.

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

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.

Cyclic Adenosine Monophosphate Accumulation and beta-Adrenergic Binding in Unweighted and Denervated Rat Soleus Muscle

NASA Technical Reports Server (NTRS)

Kirby, Christopher R.; Woodman, Christopher R.; Woolridge, Dale; Tischler, Marc E.

1992-01-01

Unweighting, but not denervation, of muscle reportedly "spares" insulin receptors, increasing insulin sensitivity. Unweighting also increases beta-adrenergic responses of carbohydrate metabolism. These differential characteristics were studied further by comparing cyclic adenosine monophosphate (cAMP) accumulation and beta-adrenergic binding in normal and 3-day unweighted or denervated soleus muscle. Submaximal amounts of isoproterenol, a p-agonist, increased cAMP accumulation in vitro and in vivo (by intramuscular (IM) injection) to a greater degree (P less than .05) in unweighted muscles. Forskolin or maximal isoproterenol had similar in vitro effects in all muscles, suggesting increased beta-adrenergic sensitivity following unweighting. Increased sensitivity was confirmed by a greater receptor density (B(sub max)) for iodo-125(-)-pindolol in particulate preparations of unweighted (420 x 10(exp -18) mol/mg muscle) than of control or denervated muscles (285 x 10(exp-18) mol/mg muscle). The three dissociation constant (Kd) values were similar (20.3 to 25.8 pmol/L). Total binding capacity (11.4 fmol/muscle) did not change during 3 days of unweighting, but diminished by 30% with denervation. This result illustrates the "sparing" and loss of receptors, respectively, in these two atrophy models. In diabetic animals, IM injection of insulin diminished CAMP accumulation in the presence of theophylline in unweighted muscle (-66% +/- 2%) more than in controls (-42% +'- 6%, P less than .001). These results show that insulin affects CAMP formation in muscle, and support a greater in vivo insulin response following unweighting atrophy. These various data support a role for lysosomal proteolysis in denervation, but not in unweighting, atrophy.

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.

Developmental Changes is Expression of Beta-Adrenergic Receptors in Cultures of C2C12 Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

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

2000-01-01

beta-Adrenergic receptor (bAR) agonists have been reported to modulate growth in several mammalian and avian species, and bAR agonists presumably exert their physiological action on skeletal muscle cells through this receptor. Because of the importance of bAR regulation on muscle protein metabolism in muscle cells, the objectives of this study were to determine the developmental expression pattern of the bAR population in C2C12 skeletal muscle cells, and to analyze changes in both the quantity and isoform expression of the major muscle protein, myosin. The number of bAR in mononucleated C2C12 cells was approximately 8,000 bAR per cell, which is comparable with the population reported in several other nonmuscle cell types. However, the bar population increased after myoblast fusion to greater than 50,000 bAR per muscle cell equivalent. The reasons for this apparent over-expression of bAR in C2C12 cells is not known. The quantity of myosin also increased after C2C12 myoblast fusion, but the quantity of myosin was less than that reported in primary muscle cell cultures. Finally, at least five different isoforms of myosin heavy chain could be resolved in C2C12 cells, and three of these exhibited either increased or decreased developmental regulation relative to the others. Thus, C2C12 myoblasts undergo developmental regulation of bAR population and myosin heavy chain isoform expression.

Terbutaline causes immobilization of single β2-adrenergic receptor-ligand complexes in the plasma membrane of living A549 cells as revealed by single-molecule microscopy

NASA Astrophysics Data System (ADS)

Sieben, Anne; Kaminski, Tim; Kubitscheck, Ulrich; Häberlein, Hanns

2011-02-01

G-protein-coupled receptors are important targets for various drugs. After signal transduction, regulatory processes, such as receptor desensitization and internalization, change the lateral receptor mobility. In order to study the lateral diffusion of β2-adrenergic receptors (β2AR) complexed with fluorescently labeled noradrenaline (Alexa-NA) in plasma membranes of A549 cells, trajectories of single receptor-ligand complexes were monitored using single-particle tracking. We found that a fraction of 18% of all β2ARs are constitutively immobile. About 2/3 of the β2ARs moved with a diffusion constant of D2 = 0.03+/-0.001 μm2/s and about 17% were diffusing five-fold faster (D3 = 0.15+/-0.02 μm2/s). The mobile receptors moved within restricted domains and also showed a discontinuous diffusion behavior. Analysis of the trajectory lengths revealed two different binding durations with τ1 = 77+/-1 ms and τ2 = 388+/-11 ms. Agonistic stimulation of the β2AR-Alexa-NA complexes with 1 μM terbutaline caused immobilization of almost 50% of the receptors within 35 min. Simultaneously, the mean area covered by the mobile receptors decreased significantly. Thus, we demonstrated that agonistic stimulation followed by cell regulatory processes results in a change in β2AR mobility suggesting that different receptor dynamics characterize different receptor states.

Antinociceptive interaction between spinal clonidine and lidocaine in the rat formalin test: an isobolographic analysis.

PubMed

Hao, S; Takahata, O; Iwasaki, H

2001-03-01

Clinical and basic science studies suggest that spinal alpha-2-adrenergic receptor agonists and local anesthetics produce analgesia, but interaction between alpha-2-adrenergic receptor agonists and local anesthetics in the persistent pain model has not been examined. In the present study, using isobolographic analysis, we investigated the antinociceptive interaction of intrathecal clonidine and lidocaine in the rat formalin test. Sprague-Dawley rats were implanted with chronic lumbar intrathecal catheters, and were tested for paw flinch by formalin injection. Biphasic painful behavior was counted. Intrathecal clonidine (3-12 nmol) was administered 15 min before formalin, and intrathecal lidocaine (375-1850 nmol) was administered 5 min before formalin. To examine the interaction of intrathecal clonidine and lidocaine, an isobolographic design was used. Spinal administration of clonidine produced dose-dependent suppression of the biphasic responses in the formalin test. Spinal lidocaine resulted in dose-dependent transient motor dysfunction and the motor dysfunction recovered to normal at 10-15 min after administration. Spinal lidocaine produced dose-dependent suppression of phase-2 activity in the formalin test. Isobolographic analysis showed that the combination of intrathecal clonidine and lidocaine synergistically reduced Phase-2 activity. We conclude that intrathecal clonidine synergistically interacts with lidocaine in reducing the nociceptive response in the formalin test. Preformalin administration of intrathecal clonidine and lidocaine dose-dependently produced antinociception in the formalin test. The combination of clonidine and lidocaine, synergistically produced suppression of nociceptive response in the persistent pain model.

Effects of long-acting beta adrenergic agonists on vocal fold ion transport.

PubMed

Sivasankar, Mahalakshmi; Blazer-Yost, Bonnie

2009-03-01

Inhaled medications prescribed for the hypersensitive airway typically combine corticosteroids and long-acting beta2 adrenergic agonists (LABAs). The phonatory side effects of these combination treatments are widely recognized. However, there is limited understanding of the physiological changes induced by these medications that underlie the phonatory side effects. The objective of this study was to investigate the distinct effects of corticosteroids and LABAs on vocal fold mucosal physiology. Understanding the physiological changes to the vocal folds after corticosteroid and LABA treatments is necessary to prevent the prevalent vocal decrement associated with these medications. Experimental in vitro design with treatment and control groups. Native porcine vocal fold mucosae (N = 38) were exposed to corticosteroid or LABA treatments. Ion transport was measured continuously at baseline and after treatment. To quantify the nature of ion transport, vocal folds were also treated with chloride and sodium channel inhibitors. Corticosteroid treatment did not alter ion transport. Conversely, exposure to LABAs significantly increased ion transport. This increase in ion transport was transient, observed immediately after treatment in all tissue and associated with increased chloride secretion. The distinct effects of corticosteroids and LABAs on vocal fold physiology have not been examined to date. This study demonstrates that short-term treatment with LABAs, but not corticosteroids, significantly increases ion transport. These findings suggest that one underlying physiological mechanism for phonatory changes associated with inhaled treatments may be related to acute alterations in vocal fold ion transport and surface hydration.

Epidural anesthesia and postoperatory analgesia with alpha-2 adrenergic agonists and lidocaine for ovariohysterectomy in bitches

PubMed Central

Pohl, Virgínia H.; Carregaro, Adriano B.; Lopes, Carlize; Gehrcke, Martielo I.; Muller, Daniel C.M.; Garlet, Clarissa D.

2012-01-01

The aim of this study was to determine the viability and cardiorespiratory effects of the association of epidural alpha-2 adrenergic agonists and lidocaine for ovariohysterectomy (OH) in bitches. Forty-two bitches were spayed under epidural anesthesia with 2.5 mg/kg body weight (BW) of 1% lidocaine with adrenaline (CON) or in association with 0.25 mg/kg BW of xylazine (XYL), 10 μg/kg BW of romifidine (ROM), 30 μg/kg BW of detomidine (DET), 2 μg/kg BW of dexmedetomidine (DEX), or 5 μg/kg BW of clonidine (CLO). Heart rate (HR), respiratory rate (fR) and arterial pressures were monitored immediately before and every 10 min after the epidural procedure. Blood gas and pH analysis were done before, and at 30 and 60 min after the epidural procedure. Animals were submitted to isoflurane anesthesia if they presented a slightest sign of discomfort during the procedure. Time of sensory epidural block and postoperative analgesia were evaluated. All animals in CON and DEX, 5 animals in ROM and CLO, 4 animals in XYL, and 3 in DET required supplementary isoflurane. All groups, except CLO, showed a decrease in HR. There was an increase in arterial pressures in all groups. Postoperative analgesia lasted the longest in XYL. None of the protocols were totally efficient to perform the complete procedure of OH; however, xylazine provided longer postoperative analgesia than the others. PMID:23277701

Clonidine blocks stress-induced craving in cocaine users.

PubMed

Jobes, Michelle L; Ghitza, Udi E; Epstein, David H; Phillips, Karran A; Heishman, Stephen J; Preston, Kenzie L

2011-11-01

Reactivity to stressors and environmental cues, a putative cause of relapse in addiction, may be a useful target for relapse-prevention medication. In rodents, alpha-2 adrenergic agonists such as clonidine block stress-induced reinstatement of drug seeking, but not drug cue-induced reinstatement. The objective of this study is to test the effect of clonidine on stress- and cue-induced craving in human cocaine users. Healthy, non-treatment-seeking cocaine users (n = 59) were randomly assigned to three groups receiving clonidine 0, 0.1, or 0.2 mg orally under double-blind conditions. In a single test session, each participant received clonidine or placebo followed 3 h later by exposure to two pairs of standardized auditory-imagery scripts (neutral/stress and neutral/drug). Subjective measures of craving were collected. Subjective responsivity ("crave cocaine" Visual Analog Scale) to stress scripts was significantly attenuated in the 0.1- and 0.2-mg clonidine groups; for drug-cue scripts, this attenuation occurred only in the 0.2-mg group. Other subjective measures of craving showed similar patterns of effects but Dose × Script interactions were not significant. Clonidine was effective in reducing stress-induced (and, at a higher dose, cue-induced) craving in a pattern consistent with preclinical findings, although this was significant on only one of several measures. Our results, though modest and preliminary, converge with other evidence to suggest that alpha-2 adrenergic agonists may help prevent relapse in drug abusers experiencing stress or situations that remind them of drug use.

Cargo-mediated regulation of a rapid Rab4-dependent recycling pathway.

PubMed

Yudowski, Guillermo A; Puthenveedu, Manojkumar A; Henry, Anastasia G; von Zastrow, Mark

2009-06-01

Membrane trafficking is well known to regulate receptor-mediated signaling processes, but less is known about whether signaling receptors conversely regulate the membrane trafficking machinery. We investigated this question by focusing on the beta-2 adrenergic receptor (B2AR), a G protein-coupled receptor whose cellular signaling activity is controlled by ligand-induced endocytosis followed by recycling. We used total internal reflection fluorescence microscopy (TIR-FM) and tagging with a pH-sensitive GFP variant to image discrete membrane trafficking events mediating B2AR endo- and exocytosis. Within several minutes after initiating rapid endocytosis of B2ARs by the adrenergic agonist isoproterenol, we observed bright "puffs" of locally increased surface fluorescence intensity representing discrete Rab4-dependent recycling events. These events reached a constant frequency in the continuous presence of isoproterenol, and agonist removal produced a rapid (observed within 1 min) and pronounced (approximately twofold) increase in recycling event frequency. This regulation required receptor signaling via the cAMP-dependent protein kinase (PKA) and a specific PKA consensus site located in the carboxyl-terminal cytoplasmic tail of the B2AR itself. B2AR-mediated regulation was not restricted to this membrane cargo, however, as transferrin receptors packaged in the same population of recycling vesicles were similarly affected. In contrast, net recycling measured over a longer time interval (10 to 30 min) was not detectably regulated by B2AR signaling. These results identify rapid regulation of a specific recycling pathway by a signaling receptor cargo.

The role of the brown adipose tissue in β3-adrenergic receptor activation-induced sleep, metabolic and feeding responses.

PubMed

Szentirmai, Éva; Kapás, Levente

2017-04-19

Brown adipose tissue (BAT) is regulated by the sympathetic nervous system via β3-adrenergic receptors (β3-AR). Here we tested the hypothesis that pharmacological stimulation of β3-ARs leads to increased sleep in mice and if this change is BAT dependent. In wild-type (WT) animals, administration of CL-316,243, a selective β3-AR agonist, induced significant increases in non-rapid-eye movement sleep (NREMS) lasting for 4-10 h. Simultaneously, electroencephalographic slow-wave activity (SWA) was significantly decreased and body temperature was increased with a delay of 5-6 h. In uncoupling protein 1 (UCP-1) knockout mice, the middle and highest doses of the β3-AR agonist increased sleep and suppressed SWA, however, these effects were significantly attenuated and shorter-lasting as compared to WT animals. To determine if somnogenic signals arising from BAT in response to β3-AR stimulation are mediated by the sensory afferents of BAT, we tested the effects of CL-316,243 in mice with the chemical deafferentation of the intra-scapular BAT pads. Sleep responses to CL-316,243 were attenuated by ~50% in intra-BAT capsaicin-treated mice. Present findings indicate that the activation of BAT via β3-AR leads to increased sleep in mice and that this effect is dependent on the presence of UCP-1 protein and sleep responses require the intact sensory innervation of BAT.

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.

Ligand-Induced Modulation of the Free-Energy Landscape of G Protein-Coupled Receptors Explored by Adaptive Biasing Techniques

PubMed Central

Provasi, Davide; Artacho, Marta Camacho; Negri, Ana; Mobarec, Juan Carlos; Filizola, Marta

2011-01-01

Extensive experimental information supports the formation of ligand-specific conformations of G protein-coupled receptors (GPCRs) as a possible molecular basis for their functional selectivity for signaling pathways. Taking advantage of the recently published inactive and active crystal structures of GPCRs, we have implemented an all-atom computational strategy that combines different adaptive biasing techniques to identify ligand-specific conformations along pre-determined activation pathways. Using the prototypic GPCR β2-adrenergic receptor as a suitable test case for validation, we show that ligands with different efficacies (either inverse agonists, neutral antagonists, or agonists) modulate the free-energy landscape of the receptor by shifting the conformational equilibrium towards active or inactive conformations depending on their elicited physiological response. Notably, we provide for the first time a quantitative description of the thermodynamics of the receptor in an explicit atomistic environment, which accounts for the receptor basal activity and the stabilization of different active-like states by differently potent agonists. Structural inspection of these metastable states reveals unique conformations of the receptor that may have been difficult to retrieve experimentally. PMID:22022248

Ability of higenamine and related compounds to enhance glucose uptake in L6 cells.

PubMed

Kato, Eisuke; Kimura, Shunsuke; Kawabata, Jun

2017-12-15

β2-Adrenergic receptor (β2AR) agonists are employed as bronchodilators to treat pulmonary disorders, but are attracting attention for their modulation of glucose handling and energy expenditure. Higenamine is a tetrahydroisoquinoline present in several plant species and has β2AR agonist activity, but the involvement of each functional groups in β2AR agonist activity and its effectiveness compared with endogenous catecholamines (dopamine, epinephrine, and norepinephrine) has rarely been studied. Glucose uptake of muscle cells are known to be induced through β2AR activation. Here, the ability to enhance glucose uptake of higenamine was compared with that of several methylated derivatives of higenamine or endogenous catecholamines. We found that: (i) the functional groups of higenamine except for the 4'-hydroxy group are required to enhance glucose uptake; (ii) higenamine shows a comparable ability to enhance glucose uptake with that of epinephrine and norepinephrine; (iii) the S-isomer shows a greater ability to enhance glucose uptake compared with that of the R-isomer. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

GSNO Reductase and β2 Adrenergic Receptor Gene-gene Interaction: Bronchodilator Responsiveness to Albuterol

PubMed Central

Choudhry, Shweta; Que, Loretta G.; Yang, Zhonghui; Liu, Limin; Eng, Celeste; Kim, Sung O.; Kumar, Gunjan; Thyne, Shannon; Chapela, Rocio; Rodriguez-Santana, Jose R.; Rodriguez-Cintron, William; Avila, Pedro C.; Stamler, Jonathan S.; Burchard, Esteban G.

2010-01-01

Background Short-acting inhaled β2-agonists such as albuterol are used for bronchodilation and are the mainstay of asthma treatment worldwide. There is significant variation in bronchodilator responsiveness to albuterol not only between individuals but also across racial/ethnic groups. The β2-adrenergic receptor (β2AR) is the target for β2-agonist drugs. The enzyme S-nitrosoglutathione reductase (GSNOR), which regulates levels of the endogenous bronchodilator S-nitrosoglutathione, has been shown to modulate the response to β2-agonists. Objective We hypothesized that there are pharmacogenetic interactions between GSNOR and β2AR gene variants which are associated with variable response to albuterol. Methods We performed family-based analyses to test for association between GSNOR gene variants and asthma and related phenotypes in 609 Puerto Rican and Mexican families with asthma. In addition, we tested these subjects for pharmacogenetic interaction between GSNOR and β2AR gene variants and responsiveness to albuterol using linear regression. Cell transfection experiments were performed to test the potential effect of the GSNOR gene variants. Results Among Puerto Ricans, several GSNOR SNPs and a haplotype in the 3′UTR were significantly associated with increased risk for asthma and lower bronchodilator responsiveness (p = 0.04 to 0.007). The GSNOR risk haplotype affects expression of GSNOR mRNA and protein, suggesting a gain of function. Furthermore, gene-gene interaction analysis provided evidence of pharmacogenetic interaction between GSNOR and β2AR gene variants and the response to albuterol in Puerto Rican (p = 0.03), Mexican (p = 0.15) and combined Puerto Rican and Mexican asthmatics (p = 0.003). Specifically, GSNOR+17059*β2AR+46 genotype combinations (TG+GG*AG and TG+GG*GG) were associated with lower bronchodilator response. Conclusion Genotyping of GSNOR and β2AR genes may be a useful in identifying Latino subjects, who might benefit from adjuvant therapy for refractory asthma. PMID:20335826

Low STAT3 expression sensitizes to toxic effects of β-adrenergic receptor stimulation in peripartum cardiomyopathy

PubMed Central

Stapel, Britta; Kohlhaas, Michael; Ricke-Hoch, Melanie; Haghikia, Arash; Erschow, Sergej; Knuuti, Juhani; Silvola, Johanna M. U.; Roivainen, Anne; Saraste, Antti; Nickel, Alexander G.; Saar, Jasmin A.; Sieve, Irina; Pietzsch, Stefan; Müller, Mirco; Bogeski, Ivan; Kappl, Reinhard; Jauhiainen, Matti; Thackeray, James T.; Scherr, Michaela; Bengel, Frank M.; Hagl, Christian; Tudorache, Igor; Bauersachs, Johann; Maack, Christoph; Hilfiker-Kleiner, Denise

2017-01-01

Abstract Aims The benefit of the β1-adrenergic receptor (β1-AR) agonist dobutamine for treatment of acute heart failure in peripartum cardiomyopathy (PPCM) is controversial. Cardiac STAT3 expression is reduced in PPCM patients. Mice carrying a cardiomyocyte-restricted deletion of STAT3 (CKO) develop PPCM. We hypothesized that STAT3-dependent signalling networks may influence the response to β-AR agonist treatment in PPCM patients and analysed this hypothesis in CKO mice. Methods and results Follow-up analyses in 27 patients with severe PPCM (left ventricular ejection fraction ≤25%) revealed that 19 of 20 patients not obtaining dobutamine improved cardiac function. All seven patients obtaining dobutamine received heart transplantation (n = 4) or left ventricular assist devices (n = 3). They displayed diminished myocardial triglyceride, pyruvate, and lactate content compared with non-failing controls. The β-AR agonist isoproterenol (Iso) induced heart failure with high mortality in postpartum female, in non-pregnant female and in male CKO, but not in wild-type mice. Iso induced heart failure and high mortality in CKO mice by impairing fatty acid and glucose uptake, thereby generating a metabolic deficit. The latter was governed by disturbed STAT3-dependent signalling networks, microRNA-199a-5p, microRNA-7a-5p, insulin/glucose transporter-4, and neuregulin/ErbB signalling. The resulting cardiac energy depletion and oxidative stress promoted dysfunction and cardiomyocyte loss inducing irreversible heart failure, which could be attenuated by the β1-AR blocker metoprolol or glucose-uptake-promoting drugs perhexiline and etomoxir. Conclusions Iso impairs glucose uptake, induces energy depletion, oxidative stress, dysfunction, and death in STAT3-deficient cardiomyocytes mainly via β1-AR stimulation. These cellular alterations may underlie the dobutamine-induced irreversible heart failure progression in PPCM patients who frequently display reduced cardiac STAT3 expression. PMID:28201733

The changing face of malignant hyperthermia: less fulminant, more insidious..

PubMed

Heytens, L; Forget, P; Scholtès, J L; Veyckemans, F

2015-07-01

Modern anaesthetic techniques have resulted in the clinical presentation of malignant hyperthermia to be more often indolent and/or insidious than truly fulminant, as previously known in the anaesthetic community. We present four recently referred cases to illustrate this point: one late-onset case, two patients with slowly progressive hypercapnia as the sole sign and a fourth patient with postoperative myalgias and elevated creatine kinase. We also discuss the reasons for the shift in typical clinical presentation. The more insidious character of malignant hyperthermia is most likely due to the lower triggering potency of modern volatile anaesthetics, the mitigating effects of several intravenous drugs (neuromuscular blocking agents, alpha 2 adrenergic receptor agonists, beta adrenergic blockade) or techniques (neuraxial anaesthesia) and the routine use of end-tidal CO2 monitoring leading to the early withdrawal of triggering drugs. Awareness among anaesthetists of this change in presentation is important since the clinical diagnosis is often more doubtful and, if corroborative evidence is not sought, the diagnosis may be delayed or missed altogether.

Noradrenergic System in Down Syndrome and Alzheimer's Disease A Target for Therapy.

PubMed

Phillips, Cristy; Fahimi, Atoossa; Das, Devsmita; Mojabi, Fatemeh S; Ponnusamy, Ravikumar; Salehi, Ahmad

2016-01-01

Locus coeruleus (LC) neurons in the brainstem send extensive noradrenergic (NE)-ergic terminals to the majority of brain regions, particularly those involved in cognitive function. Both Alzheimer's disease (AD) and Down syndrome (DS) are characterized by similar pathology including significant LC degeneration and dysfunction of the NE-ergic system. Extensive loss of NE-ergic terminals has been linked to alterations in brain regions vital for cognition, mood, and executive function. While the mechanisms by which NE-ergic abnormalities contribute to cognitive dysfunction are not fully understood, emergent evidence suggests that rescue of NE-ergic system can attenuate neuropathology and cognitive decline in both AD and DS. Therapeutic strategies to enhance NE neurotransmission have undergone limited testing. Among those deployed to date are NE reuptake inhibitors, presynaptic α-adrenergic receptor antagonists, NE prodrugs, and β-adrenergic agonists. Here we examine alterations in the NE-ergic system in AD and DS and suggest that NE-ergic system rescue is a plausible treatment strategy for targeting cognitive decline in both disorders.

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

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

Hemodynamic Effects of Midodrine After Space Flight in Astronauts Without Orthostatic Hypotension

NASA Technical Reports Server (NTRS)

Platts, Steven H.; Ziegler, Michael G.; Waters, Wendy W.; Meck, Janice V.

2006-01-01

Orthostatic hypotension and presyncope are common and potentially serious risks for astronauts returning from space. Susceptible subjects fail to generate an adequate adrenergic response to upright posture. The -1 adrenergic agonist, midodrine, may be an effective countermeasure. We tested the hypothesis that midodrine would have no negative hemodynamic effect on healthy astronauts returning from space. Five male astronauts participated in preflight and postflight tilt testing on a control flight as well as on the test flights, where midodrine (10 mg, orally) was administered after landing, approximately 1 hour before testing. None of these astronauts exhibited orthostatic hypotension or presyncope before or after either flight. Midodrine did not cause any untoward reactions in these subjects before or after flight, in fact a modest beneficial effect was seen on postflight tachycardia (p=0.036). These data show that midodrine protected against post-spaceflight increases in heart rate, without having any adverse hemodynamic effects on non-presyncopal, male astronauts. Among these subjects, midodrine was a safe cardiovascular countermeasure.

The effect of ligand efficacy on the formation and stability of a GPCR-G protein complex

PubMed Central

Yao, Xiao Jie; Vélez Ruiz, Gisselle; Whorton, Matthew R.; Rasmussen, Søren G. F.; DeVree, Brian T.; Deupi, Xavier; Sunahara, Roger K.; Kobilka, Brian

2009-01-01

G protein-coupled receptors (GPCRs) mediate the majority of physiologic responses to hormones and neurotransmitters. However, many GPCRs exhibit varying degrees of agonist-independent G protein activation. This phenomenon is referred to as basal or constitutive activity. For many of these GPCRs, drugs classified as inverse agonists can suppress basal activity. There is a growing body of evidence that basal activity is physiologically relevant, and the ability of a drug to inhibit basal activity may influence its therapeutic properties. However, the molecular mechanism for basal activation and inhibition of basal activity by inverse agonists is poorly understood and difficult to study, because the basally active state is short-lived and represents a minor fraction of receptor conformations. Here, we investigate basal activation of the G protein Gs by the β2 adrenergic receptor (β2AR) by using purified receptor reconstituted into recombinant HDL particles with a stoichiometric excess of Gs. The β2AR is site-specifically labeled with a small, environmentally sensitive fluorophore enabling direct monitoring of agonist- and Gs-induced conformational changes. In the absence of an agonist, the β2AR and Gs can be trapped in a complex by enzymatic depletion of guanine nucleotides. Formation of the complex is enhanced by the agonist isoproterenol, and it rapidly dissociates on exposure to concentrations of GTP and GDP found in the cytoplasm. The inverse agonist ICI prevents formation of the β2AR-Gs complex, but has little effect on preformed complexes. These results provide insights into G protein-induced conformational changes in the β2AR and the structural basis for ligand efficacy. PMID:19470481

β2-Agonist Induced cAMP Is Decreased in Asthmatic Airway Smooth Muscle Due to Increased PDE4D

PubMed Central

Trian, Thomas; Burgess, Janette K.; Niimi, Kyoko; Moir, Lyn M.; Ge, Qi; Berger, Patrick; Liggett, Stephen B.; Black, Judith L.; Oliver, Brian G.

2011-01-01

Background and Objective Asthma is associated with airway narrowing in response to bronchoconstricting stimuli and increased airway smooth muscle (ASM) mass. In addition, some studies have suggested impaired β-agonist induced ASM relaxation in asthmatics, but the mechanism is not known. Objective To characterize the potential defect in β-agonist induced cAMP in ASM derived from asthmatic in comparison to non-asthmatic subjects and to investigate its mechanism. Methods We examined β2-adrenergic (β2AR) receptor expression and basal β-agonist and forskolin (direct activator of adenylyl cyclase) stimulated cAMP production in asthmatic cultured ASM (n = 15) and non-asthmatic ASM (n = 22). Based on these results, PDE activity, PDE4D expression and cell proliferation were determined. Results In the presence of IBMX, a pan PDE inhibitor, asthmatic ASM had ∼50% lower cAMP production in response to isoproterenol, albuterol, formoterol, and forskolin compared to non-asthmatic ASM. However when PDE4 was specifically inhibited, cAMP production by the agonists and forskolin was normalized in asthmatic ASM. We then measured the amount and activity of PDE4, and found ∼2-fold greater expression and activity in asthmatic ASM compared to non-asthmatic ASM. Furthermore, inhibition of PDE4 reduced asthmatic ASM proliferation but not that of non-asthmatic ASM. Conclusion Decreased β-agonist induced cAMP in ASM from asthmatics results from enhanced degradation due to increased PDE4D expression. Clinical manifestations of this dysregulation would be suboptimal β-agonist-mediated bronchodilation and possibly reduced control over increasing ASM mass. These phenotypes appear to be “hard-wired” into ASM from asthmatics, as they do not require an inflammatory environment in culture to be observed. PMID:21611147

[Effect of (+/-)-pindolol on the central 5-HT1A receptor by the use of in vivo microdialysis and hippocampal slice preparations].

PubMed

Tsuji, Keiichiro

2002-06-01

Although it is suggested that (+/-)-pindolol, a beta-adrenergic/5-HT1A receptor antagonist, may enhance the efficacy of selective serotonin reuptake inhibitors (SSRI), the results of double-blind studies are contradictory and recent animal studies suggest that (+/-)-pindolol may act as a partial agonist to the 5-HT1A receptor. In this study we have investigated the effect of (+/-)-pindolol on both pre- and postsynaptic 5-HT1A receptors using in vivo microdialysis and hippocampal slice preparations. (+/-)-pindolol and flesinoxan, a 5-HT1A receptor full agonist, significantly decreased the extracellular levels of 5-HT in the raphe and prefrontal cortex. The 5-HT and other 5-HT1A receptor agonists, flesinoxan and 8-hydroxy-2- (di-n-propylamino)tetralon (8-OH-DPAT), significantly decreased the population excitatory postsynaptic potential (EPSP) in the CA3-CA1 excitatory synapse in a dose-dependent manner. The effect of 5-HT and other 5-HT1A receptor agonists accompanied the increase in paired-pulse facilitation (ppf) induced by short-interval two stimuli and were reversed by the coadministration of the 5-HT1A receptor agonist, NAN-190, but not by (+/-)-pindolol. (+/-)-pindolol also suppressed the EPSP, but this effect was not reversed by NAN-190. These results suggest that (+/-)-pindolol acts as a partial agonist to the somatodendritic 5-HT1A receptor in the raphe, whereas it may have no action on the postsynaptic 5-HT1A receptor in the hippocampus.

Effect of beta-agonists on LAM progression and treatment.

PubMed

Le, Kang; Steagall, Wendy K; Stylianou, Mario; Pacheco-Rodriguez, Gustavo; Darling, Thomas N; Vaughan, Martha; Moss, Joel

2018-01-30

Lymphangioleiomyomatosis (LAM), a rare disease of women, is associated with cystic lung destruction resulting from the proliferation of abnormal smooth muscle-like LAM cells with mutations in the tuberous sclerosis complex (TSC) genes TSC1 and/or TSC2 The mutant genes and encoded proteins are responsible for activation of the mechanistic target of rapamycin (mTOR), which is inhibited by sirolimus (rapamycin), a drug used to treat LAM. Patients who have LAM may also be treated with bronchodilators for asthma-like symptoms due to LAM. We observed stabilization of forced expiratory volume in 1 s over time in patients receiving sirolimus and long-acting beta-agonists with short-acting rescue inhalers compared with patients receiving only sirolimus. Because beta-agonists increase cAMP and PKA activity, we investigated effects of PKA activation on the mTOR pathway. Human skin TSC2 +/- fibroblasts or LAM lung cells incubated short-term with isoproterenol (beta-agonist) showed a sirolimus-independent increase in phosphorylation of S6, a downstream effector of the mTOR pathway, and increased cell growth. Cells incubated long-term with isoproterenol, which may lead to beta-adrenergic receptor desensitization, did not show increased S6 phosphorylation. Inhibition of PKA blocked the isoproterenol effect on S6 phosphorylation. Thus, activation of PKA by beta-agonists increased phospho-S6 independent of mTOR, an effect abrogated by beta-agonist-driven receptor desensitization. In agreement, retrospective clinical data from patients with LAM suggested that a combination of bronchodilators in conjunction with sirolimus may be preferable to sirolimus alone for stabilization of pulmonary function.

Enhanced noradrenergic activity in the amygdala contributes to hyperarousal in an animal model of PTSD.

PubMed

Ronzoni, Giacomo; Del Arco, Alberto; Mora, Francisco; Segovia, Gregorio

2016-08-01

Increased activity of the noradrenergic system in the amygdala has been suggested to contribute to the hyperarousal symptoms associated with post-traumatic stress disorder (PTSD). However, only two studies have examined the content of noradrenaline or its metabolites in the amygdala of rats previously exposed to traumatic stress showing inconsistent results. The aim of this study was to investigate the effects of an inescapable foot shock (IFS) procedure (1) on reactivity to novelty in an open-field (as an index of hyperarousal), and (2) on noradrenaline release in the amygdala during an acute stress. To test the role of noradrenaline in amygdala, we also investigated the effects of microinjections of propranolol, a β-adrenoreceptor antagonist, and clenbuterol, a β-adrenoreceptor agonist, into the amygdala of IFS and control animals. Finally, we evaluated the expression of mRNA levels of β-adrenoreceptors (β1 and β2) in the amygdala, the hippocampus and the prefrontal cortex. Male Wistar rats (3 months) were stereotaxically implanted with bilateral guide cannulae. After recovering from surgery, animals were exposed to IFS (10 shocks, 0.86mA, and 6s per shock) and seven days later either microdialysis or microinjections were performed in amygdala. Animals exposed to IFS showed a reduced locomotion compared to non-shocked animals during the first 5min in the open-field. In the amygdala, IFS animals showed an enhanced increase of noradrenaline induced by stress compared to control animals. Bilateral microinjections of propranolol (0.5μg) into the amygdala one hour before testing in the open-field normalized the decreased locomotion observed in IFS animals. On the other hand, bilateral microinjections of clenbuterol (30ng) into the amygdala of control animals did not change the exploratory activity induced by novelty in the open field. IFS modified the mRNA expression of β1 and β2 adrenoreceptors in the prefrontal cortex and the hippocampus. These results suggest that an increased noradrenergic activity in the amygdala contributes to the expression of hyperarousal in an animal model of PTSD. Copyright © 2016 Elsevier Ltd. All rights reserved.

β3-Adrenergic Regulation of EPC Features Through Manipulation of the Bone Marrow MSC Niche.

PubMed

Vafaei, Rana; Nassiri, Seyed Mahdi; Siavashi, Vahid

2017-12-01

Mesenchymal stem cells (MSCs) reside in a specific niche in the bone marrow, however, biological features of this niche are still not fully understood. Given the interactions of MSCs with endothelial cells in different tissues, bone marrow MSC niche may influence the biological features of endothelial progenitor cells (EPCs). To understand the role of the sympathetic nervous system in regulation of the MSC niche, we examined whether the manipulation of the MSC niche via β3-adrenergic signals will affect EPC features. A selective β3 agonist (BRL37344) or a β3 antagonist (SR59230A) was administered in mice for 2 weeks to determine the potential effects of these regimens on the population of CD133 + stem cells in the bone marrow. Then, bone marrow-derived MSCs and EPCs were harvested and expanded from the mice to examine the effect of changes in the MSC niche on EPC features. Improved MSC colony forming potency with increased bone marrow stromal cell-derived factor 1 (SDF-1) (also known as C-X-C motif chemokine 12 [CXCL12]) expression was shown as a result of intensification of the bone marrow adrenergic signals through BRL37344 injection. On the other hand, the blockage of these signals limited the expression level of SDF-1 and resulted in bone marrow enrichment of CD133 + cells. Manipulation of the MSC niche and decreased SDF-1 expression via SR59230A injection also prompted EPCs to form more colonies with augmented proliferation and differentiation capacity. Overall, our results indicate that the β3-adrenergic signals regulate the MSC niche, thereby resulting in modulation of EPC biological features. J. Cell. Biochem. 118: 4753-4761, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Ca2+-associated triphasic pH changes in mitochondria during brown adipocyte activation.

PubMed

Hou, Yanyan; Kitaguchi, Tetsuya; Kriszt, Rókus; Tseng, Yu-Hua; Raghunath, Michael; Suzuki, Madoka

2017-08-01

Brown adipocytes (BAs) are endowed with a high metabolic capacity for energy expenditure due to their high mitochondria content. While mitochondrial pH is dynamically regulated in response to stimulation and, in return, affects various metabolic processes, how mitochondrial pH is regulated during adrenergic stimulation-induced thermogenesis is unknown. We aimed to reveal the spatial and temporal dynamics of mitochondrial pH in stimulated BAs and the mechanisms behind the dynamic pH changes. A mitochondrial targeted pH-sensitive protein, mito-pHluorin, was constructed and transfected to BAs. Transfected BAs were stimulated by an adrenergic agonist, isoproterenol. The pH changes in mitochondria were characterized by dual-color imaging with indicators that monitor mitochondrial membrane potential and heat production. The mechanisms of pH changes were studied by examining the involvement of electron transport chain (ETC) activity and Ca 2+ profiles in mitochondria and the intracellular Ca 2+ store, the endoplasmic reticulum (ER). A triphasic mitochondrial pH change in BAs upon adrenergic stimulation was revealed. In comparison to a thermosensitive dye, we reveal that phases 1 and 2 of the pH increase precede thermogenesis, while phase 3, characterized by a pH decrease, occurs during thermogenesis. The mechanism of pH increase is partially related to ETC. In addition, the pH increase occurs concurrently with an increase in mitochondrial Ca 2+ . This Ca 2+ increase is contributed to by an influx from the ER, and it is further involved in mitochondrial pH regulation. We demonstrate that an increase in mitochondrial pH is implicated as an early event in adrenergically stimulated BAs. We further suggest that this pH increase may play a role in the potentiation of thermogenesis.

Renal and femoral venous blood flows are regulated by different mechanisms dependent on α-adrenergic receptor subtypes and nitric oxide in anesthetized rats.

PubMed

Fioretti, Alexandre C; Ogihara, Cristiana A; Cafarchio, Eduardo M; Venancio, Daniel P; de Almeida, Roberto Lopes; Antonio, Bruno B; Sato, Monica A

2017-12-01

Venous and arterial walls are responsive to sympathetic system and circulating substances, nevertheless, very few is known about the venous blood flow regulation simultaneously to arterial vascular beds. In this study, we compared the venous and arterial blood flow regulation in visceral and muscular beds upon injection of different doses of vasoactive drugs which act in arterial vascular beds. Anesthetized adult male Wistar rats underwent to right femoral artery and vein cannulation for hemodynamic recordings and infusion of drugs. Doppler flow probes were placed around the left renal artery and vein, and left femoral artery and vein to evaluate the changes in flood flow. Phenylephrine (PHE) injection (α 1 -adrenergic receptor agonist) elicited vasoconstriction in all arteries and veins. Intravenous prazosin (PZS) (1mg/kg, α 1 -adrenergic receptor blocker) caused renal artery vasodilation, but not in the other beds. Vasoconstrictor effect of PHE was abolished by PZS in all vascular beds, except in femoral vein. Phentolamine (PTL) injection (1mg/kg, α 1 /α 2 -adrenergic receptor blocker) produced renal artery vasodilation with no change in other beds. After PTL, the vasoconstriction evoked by PHE was abolished in all vascular beds. Sodium Nitroprusside (SNP), a nitric oxide donor, elicited vasodilation in all beds, and after PTL but not post PZS injection, SNP enhanced the vasodilatory effect in femoral vein. Our findings suggest that the vasoconstriction in renal and femoral veins is mediated by different subtypes of α-adrenoceptors. The nitric oxide-dependent vasodilation in femoral vein enhances when α 2 -adrenoceptors are not under stimulation, but not in the other vascular beds investigated. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

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

β-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase

PubMed Central

Limberg, Jacqueline K.; Johansson, Rebecca E.; Peltonen, Garrett L.; Harrell, John W.; Kellawan, J. Mikhail; Eldridge, Marlowe W.; Sebranek, Joshua J.

2016-01-01

We tested the hypothesis that women exhibit greater vasodilator responses to β-adrenoceptor stimulation compared with men. We further hypothesized women exhibit a greater contribution of nitric oxide synthase and cyclooxygenase to β-adrenergic-mediated vasodilation compared with men. Forearm blood flow (Doppler ultrasound) was measured in young men (n = 29, 26 ± 1 yr) and women (n = 33, 25 ± 1 yr) during intra-arterial infusion of isoproterenol (β-adrenergic agonist). In subset of subjects, isoproterenol responses were examined before and after local inhibition of nitric oxide synthase [NG-monomethyl-l-arginine (l-NMMA); 6 male/10 female] and/or cyclooxygenase (ketorolac; 5 male/5 female). Vascular conductance (blood flow ÷ mean arterial pressure) was calculated to assess vasodilation. Vascular conductance increased with isoproterenol infusion (P < 0.01), and this effect was not different between men and women (P = 0.41). l-NMMA infusion had no effect on isoproterenol-mediated dilation in men (P > 0.99) or women (P = 0.21). In contrast, ketorolac infusion markedly increased isoproterenol-mediated responses in both men (P < 0.01) and women (P = 0.04) and this rise was lost with subsequent l-NMMA infusion (men, P < 0.01; women, P < 0.05). β-Adrenergic vasodilation is not different between men and women and sex differences in the independent contribution of nitric oxide synthase and cyclooxygenase to β-mediated vasodilation are not present. However, these data are the first to demonstrate β-adrenoceptor activation of cyclooxygenase suppresses nitric oxide synthase signaling in human forearm microcirculation and may have important implications for neurovascular control in both health and disease. PMID:26747505

Inhibition of Adrenergic and Non-Adrenergic Smooth Muscle Contraction in the Human Prostate by the Phosphodiesterase 10-Selective Inhibitor TC-E 5005.

PubMed

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

2016-11-01

The phosphodiesterase (PDE) 5 inhibitor tadalafil is available for treatment of male lower urinary tract symptoms (LUTS), while the role of other PDE isoforms for prostate smooth muscle tone is still unknown. Here, we examined effects of the PDE10-selective inhibitor TC-E 5005 on smooth muscle contraction in human prostate tissue. Prostate samples were obtained from patients undergoing radical prostatectomy. Expression of PDE10 was addressed by RT-PCR, Western blot, and fluorescence staining with different markers. Effects of TC-E 5005 and tadalafil on contraction, and relaxation of prostate strips were studied via organ bath. PDE10A was detectable by RT-PCR, Western blot, and fluorescence staining in prostate tissues. Colocalization with markers suggested expression of PDE10A in smooth muscle cells and catecholaminergic nerves. Norepinephrine, the α1 -adrenergic agonist phenylephrine, the thromboxane A2 analogue U46619, and endothelins 1-3 induced concentration-dependent contractions of prostate strips, while electric field stimulation (EFS) induced frequence-dependent contractions. Application of TC-E 5005 (500 nM) caused significant inhibition of norepinephrine-, phenylephrine-, and endothelin-3-induced contractions. Inhibition of EFS-induced contractions by TC-E 5005 ranged around 50%, resembling inhibition of EFS-induced contractions by tadalafil (10 μM). The prostacyclin analog treprostinil and the nitric oxide donor DEA NONOate induced relaxations of precontracted prostate strips, which were significantly amplified by TCE 5005. The PDE10-selective inhibitor TC-E 5005 inhibits adrenergic and neurogenic smooth muscle contractions in the human prostate. TC-E 5005 inhibits neurogenic contractions with similar efficacy than tadalafil, so that urodynamic effects in vivo appear possible. Prostate 76:1364-1374, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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.

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.

Opioid, calcium, and adrenergic receptor involvement in protopine analgesia.

PubMed

Xu, Q; Jin, R L; Wu, Y Y

1993-11-01

The analgesic effect of protopine (Pro), an alkaloid isolated from Papaveraceae, was confirmed by tail-pinch and hot-plate tests when given sc 10-40 mg.kg-1, and 20-40 mg.kg-1 inhibited the spontaneous movements of mice. Pro 40 mg.kg-1 increased the sleeping rate, prolonged the sleeping duration, and shortened the sleeping latency in mice hypnotized by ip pentobarbital sodium 30 mg.kg-1. Pro 10-40 mg.kg-1 did not affect the inflammatory reaction induced by xylene and egg white. An icv injection of Pro 20-200 micrograms/mouse showed a remarkable analgesic effect in mice. The icv pretreatment of naloxone 2 micrograms blocked the analgesic effect completely. CaCl2 40 micrograms/mouse (ICV) or methotrexate 10 mg.kg-1 (ip), an agonist of Ca2+ channel, showed a complete blockade of the analgesia, while nifedipine 100 mg.kg-1(po), a blocker of Ca2+ channel, enhanced the analgesic effect. The ip pretreatment of reserpine 4 mg.kg-1 reduced the Pro analgesia. Phentolamine 10 mg.kg-1(ip), an alpha-adrenergic blocker, tended to weaken the analgesia, but propranolol 10 mg.kg-1(ip), a beta-blocker, did not affect it. These results suggest that Pro displays its analgesic effect mainly through the opioid and calcium systems and partly through the adrenergic mechanism.

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.

Contrasting metabolic effects of antihypertensive agents.

PubMed

Velliquette, Rodney A; Ernsberger, Paul

2003-12-01

Hypertension often coexists with hyperlipidemia, insulin resistance, and glucose intolerance, a comorbidity known as metabolic syndrome X. Different antihypertensives have mixed effects on these associated abnormalities. We compared three antihypertensives in the spontaneously hypertensive obese rat model of syndrome X. Moxonidine (4 mg/kg), an imidazoline and alpha2-adrenergic agonist, alpha-methyldopa (200 mg/kg), an alpha2-adrenergic agonist, or the vasodilator hydralazine (10 mg/kg) was given orally for 15 d. All three agents lowered blood pressure equally. Moxonidine significantly reduced fasting plasma insulin, glucagon, cholesterol, triglycerides, and free fatty acids (FFA) compared with untreated controls. In contrast, syndrome X markers were not affected by alpha-methyldopa treatment, and hydralazine reduced only glucagon and FFA. Relative to untreated controls, moxonidine improved glucose tolerance as shown by reduced glucose area under the curve (AUC) (13.6 +/- 2.4 versus 42.5 +/- 9.9 g x min/dl). Insulin AUC was increased (7.4 +/- 0.9 versus 3.9 +/- 1.8 microg x min/ml) as was the plasma C-peptide response to the glucose load. In contrast, alpha-methyldopa and hydralazine worsened glucose tolerance (68 +/- 26 and 110 +/- 21 g x min/ml, respectively) and significantly reduced insulin AUC (2.5 +/- 0.8 and -2.3 +/- 1.0 microg x min/ml, respectively) compared with controls. Moxonidine reduced but alpha-methyldopa and hydralazine elevated glucagon levels after the glucose load. Contrary to the "hemodynamic hypothesis" for the metabolic actions of antihypertensives, which predicts roughly equal benefits, only moxonidine had a positive impact on comorbidities. This unique action suggests a role for direct stimulation of imidazoline receptors.

Thymol, a dietary monoterpene phenol abrogates mitochondrial dysfunction in β-adrenergic agonist induced myocardial infarcted rats by inhibiting oxidative stress.

PubMed

Nagoor Meeran, M F; Jagadeesh, G S; Selvaraj, P

2016-01-25

Mitochondrial dysfunction has been suggested to be one of the important pathological events in isoproterenol (ISO), a synthetic catecholamine and β-adrenergic agonist induced myocardial infarction (MI). In this context, we have evaluated the impact of thymol against ISO induced oxidative stress and calcium uniporter malfunction involved in the pathology of mitochondrial dysfunction in rats. Male albino Wistar rats were pre and co-treated with thymol (7.5 mg/kg body weight) daily for 7 days. Isoproterenol (100 mg/kg body weight) was subcutaneously injected into rats on 6th and 7th day to induce MI. To explore the extent of cardiac mitochondrial damage, the activities/levels of cardiac marker enzymes, mitochondrial lipid peroxidation products, antioxidants, lipids, calcium, adenosine triphosphate and multi marker enzymes were evaluated. Isoproterenol induced myocardial infarcted rats showed a significant increase in the activities of cardiac diagnostic markers, heart mitochondrial lipid peroxidation, lipids, calcium, and a significant decrease in the activities/levels of heart mitochondrial superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, isocitrate, malate, α-ketoglutarate and NADH-dehydrogenases, cytochrome-C-oxidase, and adenosine triphosphate. Thymol pre and co-treatment showed near normalized effects on all the biochemical parameters studied. Transmission electron microscopic findings and mitochondrial swelling studies confirmed our biochemical findings. The in vitro study also revealed the potent free-radical scavenging activity of thymol. Thus, thymol attenuates the involvement of ISO against oxidative stress and calcium uniporter malfunction associated with mitochondrial dysfunction in rats. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Differentiation of human pluripotent stem cells into highly functional classical brown adipocytes.

PubMed

Nishio, Miwako; Saeki, Kumiko

2014-01-01

We describe a detailed method for directed differentiation of human pluripotent stem cells, including human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), into functional classical brown adipocytes (BAs) under serum-free and feeder-free conditions. It is a two-tiered culture system, based on very simple techniques, a floating culture and a subsequent adherent culture. It does not require gene transfer. The entire process can be carried out in about 10 days. The key point is the usage of our special hematopoietic cytokine cocktail. Almost all the differentiated cells express uncoupling protein 1, a BA-selective marker, as determined by immunostaining. The differentiated cells show characteristics of classical BA as assessed by morphology and gene/protein expression. Moreover, the expression of myoblast marker genes is transiently induced during the floating culture step. hESC/hiPSC-derived BAs show significantly higher oxygen consumption rates (OCRs) than white adipocytes generated from human mesenchymal stem cell. They also show responsiveness to adrenergic stimuli, with about twofold upregulation in OCR by β-adrenergic receptor (β-AR) agonist treatments. hESC/hiPSC-derived BAs exert in vivo calorigenic activities in response to β-AR agonist treatments as assessed by thermography. Finally, lipid and glucose metabolisms are significantly improved in hESC/hiPSC-derived BA-transplanted mice. Our system provides a highly feasible way to produce functional classical BA bearing metabolism-improving capacities from hESC/hiPSC under a feeder-free and serum-free condition without gene transfer. © 2014 Elsevier Inc. All rights reserved.

Inhibition of tracheal vascular extravasation by liposome-encapsulated albuterol in rats.

PubMed

Zhang, W; Guo, L; Nadel, J A; Papahadjopoulos, D

1998-03-01

To develop a liposome-based system for systemic delivery of anti-inflammatory drugs to airways and other inflamed tissues. Postcapillary venular gap junctions open during airway inflammation and allow fluid accumulation and permit molecules (e.g. complement, kininogen) to enter tissues, initiating inflammatory cascades. Beta-adrenergic agonists prevent inflammatory plasma extravasation, but because of their deleterious side effects, they are not used intravenously. When sterically stabilized "stealth" liposomes are injected i.v., they remain in the circulation for long periods. Inflammatory mediators [e.g., substance P(SP)] open postcapillary venular gaps and allow liposomes and their contents to be deposited selectively in the inflamed tissue. We hypothesized that liposomes encapsulating a beta-adrenergic agonist, such as albuterol, would deposit selectively in inflamed airway tissue, where the drug would slowly leak out of the liposomes, resulting in closure of the gaps, thus preventing subsequent inflammatory extravasation. To test this hypothesis, we delivered albuterol-loaded liposomes i.v. in rats. Then we injected SP to open the venular gaps and allow accumulation of the drug-loaded liposomes in airway tissue. We examined whether this treatment resulted in inhibition of subsequent plasma extravasation induced by SP. The results indicate that liposome-encapsulated albuterol inhibits subsequent extravasation, presumably by leaking out of liposomes in airway tissue. This inhibition occurs for prolonged periods of time and with limited side effects compared to the effect of free albuterol. We conclude that liposomes loaded with appropriate drugs, by migrating to inflamed tissue and subsequently inhibiting inflammatory cascades, may be of therapeutic value in inflammatory diseases.

Interaction with beta-arrestin determines the difference in internalization behavor between beta1- and beta2-adrenergic receptors.

PubMed

Shiina, T; Kawasaki, A; Nagao, T; Kurose, H

2000-09-15

The beta(1)-adrenergic receptor (beta(1)AR) shows the resistance to agonist-induced internalization. As beta-arrestin is important for internalization, we examine the interaction of beta-arrestin with beta(1)AR with three different methods: intracellular trafficking of beta-arrestin, binding of in vitro translated beta-arrestin to intracellular domains of beta(1)- and beta(2)ARs, and inhibition of betaAR-stimulated adenylyl cyclase activities by beta-arrestin. The green fluorescent protein-tagged beta-arrestin 2 translocates to and stays at the plasma membrane by beta(2)AR stimulation. Although green fluorescent protein-tagged beta-arrestin 2 also translocates to the plasma membrane, it returns to the cytoplasm 10-30 min after beta(1)AR stimulation. The binding of in vitro translated beta-arrestin 1 and beta-arrestin 2 to the third intracellular loop and the carboxyl tail of beta(1)AR is lower than that of beta(2)AR. The fusion protein of beta-arrestin 1 with glutathione S-transferase inhibits the beta(1)- and beta(2)AR-stimulated adenylyl cyclase activities, although inhibition of the beta(1)AR-stimulated activity requires a higher concentration of the fusion protein than that of the beta(2)AR-stimulated activity. These results suggest that weak interaction of beta(1)AR with beta-arrestins explains the resistance to agonist-induced internalization. This is further supported by the finding that beta-arrestin can induce internalization of beta(1)AR when beta-arrestin 1 does not dissociate from beta(1)AR by fusing to the carboxyl tail of beta(1)AR.

Altered Sympathetic-to-Immune Cell Signaling via β 2-Adrenergic Receptors in Adjuvant Arthritis

PubMed Central

Bellinger, Denise L.; Schaller, Jill A.; Osredkar, Tracy

2013-01-01

Adjuvant-induced arthritic (AA) differentially affects norepinephrine concentrations in immune organs, and in vivo β-adrenergic receptor (β-AR) agonist treatment distinctly regulates ex vivo cytokine profiles in different immune organs. We examined the contribution of altered β-AR functioning in AA to understand these disparate findings. Twenty-one or 28 days after disease induction, we examined β 2-AR expression in spleen and draining lymph nodes (DLNs) for the arthritic limbs using radioligand binding and western blots and splenocyte β-AR-stimulated cAMP production using enzyme-linked immunoassay (EIA). During severe disease, β-AR agonists failed to induce splenocyte cAMP production, and β-AR affinity and density declined, indicating receptor desensitization and downregulation. Splenocyte β 2-AR phosphorylation (pβ 2-AR) by protein kinase A (pβ 2-ARPKA) decreased in severe disease, and pβ 2-AR by G protein-coupled receptor kinases (pβ 2-ARGRK) increased in chronic disease. Conversely, in DLN cells, pβ 2-ARPKA rose during severe disease, but fell during chronic disease, and pβ 2-ARGRK increased during both disease stages. A similar pβ 2-AR pattern in DLN cells with the mycobacterial cell wall component of complete Freund's adjuvant suggests that pattern recognition receptors (i.e., toll-like receptors) are important for DLN pβ 2-AR patterns. Collectively, our findings indicate lymphoid organ- and disease stage-specific sympathetic dysregulation, possibly explaining immune compartment-specific differences in β 2-AR-mediated regulation of cytokine production in AA and rheumatoid arthritis. PMID:24194774

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

Permanent effects of postnatal administration of beta-adrenergic ligands on the volume of sexually dimorphic nucleus of the preoptic area (SDN-POA) in rats.

PubMed

Izdebska-Straszak, Grazyna; Gubala, Elzbieta; Jedrzejowska-Szypulka, Halina; Klencki, Mariusz; Wiczkowski, Andrzej; Jarzab, Barbara

2006-01-01

beta-adrenergic ligands have been shown to influence sexual differentiation of the brain. In the present study we document that short postnatal treatment with beta-adrenergic agonists or antagonists may permanently reverse the morphological sex of the brain, as judged by the volume of sexually dimorphic nucleus of the preoptic area (SDN-POA). Female rats treated by beta(2)-adrenergic stimulating ligands exhibit an increased, male type SDN-POA volume while male rats treated by beta1-adrenergic antagonists show a decreased, female type of SDN-POA volume. To analyze the volume of SDN-POA of adult rats after postnatal administration of betaadrenergic ligands. From the second day of life, over 5 consecutive days, all the neonates were injected subcutaneously with the following drugs: isoproterenol, salbutamol, metoprolol alprenolol or saline. SDN-POA volumes were estimated planimetrically on serial brain slides. In male rats the mean volume of SDN-POA was 9.97 +/- 1.66 x 10(-3) mm(3), in female rats the respective volume reached 4.02 +/- 1.26 x 10(-3) mm(3) only and was 2.5 times lower, the difference being highly statistically significant. Postnatal administration of isoproterenol remained without effect in male rats but diminished the SDN-POA volume in female rats, thus increasing the sexual dimorphism. The disappearance of sexual dimorphism was noted in rats treated postnatally with salbutamol. This effect was due to the increase in SDN-POA volumes in female rats, up to 9.81 +/- 2.64 x 10(-3) mm(3), the levels approaching the male type of POA differentiation. Postnatal alprenolol treatment influenced the sexual dimorphism of the brain by decreasing the SDN-POA volume reached by adult males. In fact, in rats treated postnatally with alprenolol, the volume of the nucleus reached only 4,44 +/- 1,61 x 10(-3) mm(3), being not statistically different from female nuclei. The effect of metoprolol pretreatment was similar to alprenolol. Male volumes of SDN-POA were restored both by isoproterenol and salbutamol in metoprolol pretreated rats and by isoproterenol only in alprenolol treated rats. It appears that inhibition of beta(1)-adrenergic pathway is able to shut off the physiologic mechanisms of male differentiation of SDN-POA, and the subsequent beta(2)-adrenergic stimulation activates an alternative mechanism of masculinization. beta(2)-adrenergic signal is able to masculinize rat preoptic area in females as well. From the presented data it may be concluded that beta adrenoreceptors participate in sexual differentiation of preoptic area in rats and the modulation of their activity in postnatal period permanently influences the morphology of the sexually differentiated nucleus of the preoptic area.

Histaminergic H3-Heteroreceptors as a Potential Mediator of Betahistine-Induced Increase in Cochlear Blood Flow.

PubMed

Bertlich, Mattis; Ihler, Friedrich; Freytag, Saskia; Weiss, Bernhard G; Strupp, Michael; Canis, Martin

2015-01-01

Betahistine is a histamine-like drug that is considered beneficial in Ménière's disease by increasing cochlear blood flow. Acting as an agonist at the histamine H1-receptor and as an inverse agonist at the H3-receptor, these receptors as well as the adrenergic α2-receptor were investigated for betahistine effects on cochlear blood flow. A total of 54 Dunkin-Hartley guinea pigs were randomly assigned to one of nine groups treated with a selection of H1-, H3- or α2-selective agonists and antagonists together with betahistine. Cochlear blood flow and mean arterial pressure were recorded for 3 min before and 15 min after infusion. Blockage of the H3- or α2-receptors caused a suppression of betahistine-mediated typical changes in cochlear blood flow or blood pressure. Activation of H3-receptors caused a drop in cochlear blood flow and blood pressure. H1-receptors showed no involvement in betahistine-mediated changes of cochlear blood flow. Betahistine most likely affects cochlear blood flow through histaminergic H3-heteroreceptors. © 2015 S. Karger AG, Basel.

Profound and Rapid Reduction in Body Temperature Induced by the Melanocortin Receptor Agonists

PubMed Central

Xu, Yuanzhong; Kim, Eun Ran; Fan, Shengjie; Xia, Yan; Xu, Yong; Huang, Cheng; Tong, Qingchun

2014-01-01

The melanocortin receptor 4 (MC4R) plays a major role in body weight regulation and its agonist MTII has been widely used to study the role of MC4Rs in energy expenditure promotion and feeding reduction. Unexpectedly, we observed that intraperitoneal (i.p.) administration of MTII induced a rapid reduction in both body temperature and energy expenditure, which was independent of its effect on feeding and followed by a prolonged increase in energy expenditure. The rapid reduction was at least partly mediated by brain neurons since intracerebroventricular (icv) administration of alpha melanocyte-stimulating hormone, an endogenous melanocortin receptor agonist, produced a similar response. In addition, the body temperature-lowering effect of MTII was independent of the presence of MC4Rs, but in a similar fashion to the previously shown effect on body temperature by 5′AMP. Moreover, β-adrenergic receptors (β-ARs) were required for the recovery from low body temperature induced by MTII and further pharmacological studies showed that the MTII’s effect on body temperature may be partially mediated by the vasopressin V1a receptors. Collectively, our results reveal a previously unappreciated role for the melanocortin pathway in rapidly lowering body temperature. PMID:25065745

Osteoprotegerin and β2-Agonists Mitigate Muscular Dystrophy in Slow- and Fast-Twitch Skeletal Muscles.

PubMed

Dufresne, Sébastien S; Boulanger-Piette, Antoine; Frenette, Jérôme

2017-03-01

Our recent work showed that daily injections of osteoprotegerin (OPG)-immunoglobulin fragment complex (OPG-Fc) completely restore the function of fast-twitch extensor digitorum longus muscles in dystrophic mdx mice, a murine model of Duchenne muscular dystrophy. However, despite marked improvements, OPG-Fc was not as effective in preventing the loss of function of slow-twitch soleus and diaphragm muscles. Because β 2 -agonists enhance the function of slow- and fast-twitch dystrophic muscles and because their use is limited by their adverse effects on bone and cardiac tissues, we hypothesized that OPG-Fc, a bone and skeletal muscle protector, acts synergistically with β 2 -agonists and potentiates their positive effects on skeletal muscles. We observed that the content of β 2 -adrenergic receptors, which are mainly expressed in skeletal muscle, is significantly reduced in dystrophic muscles but is rescued by the injection of OPG-Fc. Most important, OPG-Fc combined with a low dose of formoterol, a member of a new generation of β 2 -agonists, histologically and functionally rescued slow-twitch dystrophic muscles. This combination of therapeutic agents, which have already been tested and approved for human use, may open up new therapeutic avenues for Duchenne muscular dystrophy and possibly other neuromuscular diseases. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Dietary supplement for energy and reduced appetite containing the β-agonist isopropyloctopamine leads to heart problems and hospitalisations.

PubMed

Bovee, Toine F H; Mol, Hans G J; Bienenmann-Ploum, Monique E; Heskamp, Henri H; Van Bruchem, Gerard D; Van Ginkel, Leendert A; Kooijman, Martin; Lasaroms, Johan J P; Van Dam, Ruud; Hoogenboom, Ron L A P

2016-05-01

In 2013 the Dutch authorities issued a warning against a dietary supplement that was linked to 11 reported adverse reactions, including heart problems and in one case even a cardiac arrest. In the UK a 20-year-old woman, said to have overdosed on this supplement, died. Since according to the label the product was a herbal mixture, initial LC-MS/MS analysis focused on the detection of plant toxins. Yohimbe alkaloids, which are not allowed to be present in herbal preparations according to Dutch legislation, were found at relatively high levels (400-900 mg kg(-1)). However, their presence did not explain the adverse health effects reported. Based on these effects the supplement was screened for the presence of a β-agonist, using three different biosensor assays, i.e. the validated competitive radioligand β2-adrenergic receptor binding assay, a validated β-agonists ELISA and a newly developed multiplex microsphere (bead)-based β-agonist assay with imaging detection (MAGPIX(®)). The high responses obtained in these three biosensors suggested strongly the presence of a β-agonist. Inspection of the label indicated the presence of N-isopropyloctopamine. A pure standard of this compound was bought and shown to have a strong activity in the three biosensor assays. Analysis by LC-full-scan high-resolution MS confirmed the presence of this 'unknown known' β3-agonist N-isopropyloctopamine, reported to lead to heart problems at high doses. A confirmatory quantitative analysis revealed that one dose of the preparation resulted in an intake of 40-60 mg, which is within the therapeutic range of this compound. The case shows the strength of combining bioassays with chemical analytical techniques for identification of illegal pharmacologically active substances in food supplements.

The cellular distribution of fluorescently labeled arrestins provides a robust, sensitive, and universal assay for screening G protein-coupled receptors.

PubMed

Oakley, Robert H; Hudson, Christine C; Cruickshank, Rachael D; Meyers, Diane M; Payne, Richard E; Rhem, Shay M; Loomis, Carson R

2002-11-01

G protein-coupled receptors (GPCRs) have proven to be a rich source of therapeutic targets; therefore, finding compounds that regulate these receptors is a critical goal in drug discovery. The Transfluor technology utilizes the redistribution of fluorescently labeled arrestins from the cytoplasm to agonist-occupied receptors at the plasma membrane to monitor quantitatively the activation or inactivation of GPCRs. Here, we show that the Transfluor technology can be quantitated on the INCell Analyzer system (INCAS) using the vasopressin V(2) receptor (V(2)R), which binds arrestin with high affinity, and the beta(2)-adrenergic receptor (beta(2)AR), which binds arrestin with low affinity. U2OS cells stably expressing an arrestin-green fluorescent protein conjugate and either the V(2)R or the beta(2)AR were plated in 96-well plastic plates and analyzed by the INCAS at a screening rate of 5 min per plate. Agonist dose-response and antagonist dose-inhibition curves revealed signal-to-background ratios of approximately 25:1 and 8:1 for the V(2)R and beta(2)AR, respectively. EC(50) values agreed closely with K(d) values reported in the literature for the different receptor agonists. In addition, small amounts of arrestin translocation induced by sub-EC(50) doses of agonist were distinguished from the background noise of untreated cells. Furthermore, differences in the magnitude of arrestin translocation distinguished partial agonists from full agonists, and Z' values for these ligands were >0.5. These data show that the Transfluor technology, combined with an automated image analysis system, provides a direct, robust, and universal assay for high throughput screening of known and orphan GPCRs.

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.

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.

Therapeutic potential of functional selectivity in the treatment of heart failure.

PubMed

Christensen, Gitte Lund; Aplin, Mark; Hansen, Jakob Lerche

2010-10-01

Adrenergic and angiotensin receptors are prominent targets in pharmacological alleviation of cardiac remodeling and heart failure, but their use is associated with cardiodepressant side effects. Recent advances in our understanding of seven transmembrane receptor signaling show that it is possible to design ligands with "functional selectivity," acting as agonists on certain signaling pathways while antagonizing others. This represents a major pharmaceutical opportunity to separate desired from adverse effects governed by the same receptor. Accordingly, functionally selective ligands are currently pursued as next-generation drugs for superior treatment of heart failure. Copyright © 2010 Elsevier Inc. All rights reserved.

Acute Myocardial Infarction from Coronary Vasospasm Precipitated by Pseudoephedrine and Metoprolol Use.

PubMed

Meoli, Elise M; Goldsweig, Andrew M; Malm, Brian J

2017-05-01

Pseudoephedrine is a sympathomimetic α- and β-adrenergic receptor agonist that causes vasoconstriction and reduction in edema throughout the nasal passages. Coronary vasospasm associated with pseudoephedrine has been reported in the literature. We discuss the case of a patient with new-onset atrial fibrillation receiving metoprolol for rate control on a background of pseudoephedrine use for allergic rhinitis leading to acute myocardial infarction from multivessel coronary vasospasm. This case illustrates the importance of understanding the pharmacology of potential drug-drug interactions when managing patients with acute cardiovascular syndromes. Published by Elsevier Inc.

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

Raf kinase inhibitor protein: lessons of a better way for β‐adrenergic receptor activation in the heart

PubMed Central

Rosner, Marsha Rich; Brand, Theresa; Schmitt, Joachim P

2017-01-01

Abstract Stimulation of β‐adrenergic receptors (βARs) provides the most efficient physiological mechanism to enhance contraction and relaxation of the heart. Activation of βARs allows rapid enhancement of myocardial function in order to fuel the muscles for running and fighting in a fight‐or‐flight response. Likewise, βARs become activated during cardiovascular disease in an attempt to counteract the restrictions of cardiac output. However, long‐term stimulation of βARs increases the likelihood of cardiac arrhythmias, adverse ventricular remodelling, decline of cardiac performance and premature death, thereby limiting the use of βAR agonists in the treatment of heart failure. Recently the endogenous Raf kinase inhibitor protein (RKIP) was found to activate βAR signalling of the heart without adverse effects. This review will summarize the current knowledge on RKIP‐driven compared to receptor‐mediated signalling in cardiomyocytes. Emphasis is given to the differential effects of RKIP on β1‐ and β2‐ARs and their downstream targets, the regulation of myocyte calcium cycling and myofilament activity. PMID:28444807

Norepinephrine and Stimulant Addiction

PubMed Central

Sofuoglu, Mehmet; Sewell, R. Andrew

2008-01-01

No pharmacotherapies are approved for stimulant use disorders, which are an important public health problem. Stimulants increase synaptic levels of the monoamines dopamine (DA), serotonin (5-HT), and norepinephrine (NE). Stimulant reward is attributable mostly to increased DA in the reward circuitry, although DA stimulation alone cannot explain the rewarding effects of stimulants. The noradrenergic system, which uses NE as the main chemical messenger, serves multiple brain functions including arousal, attention, mood, learning, memory, and stress response. In preclinical models of addiction, NE is critically involved in mediating stimulant effects including sensitization, drug discrimination, and reinstatement of drug seeking. In clinical studies, adrenergic blockers have shown promise as treatments for cocaine abuse and dependence, especially in patients experiencing severe withdrawal symptoms. Disulfiram, which blocks NE synthesis, increased the number of cocaine-negative urines in five randomized clinical trials. Lofexidine, an α2-adrenergic agonist, reduces the craving induced by stress and drug cues in drug users. In addition, the norepinephrine transporter (NET) inhibitor atomoxetine attenuates some of d-amphetamine’s subjective and physiological effects in humans. These findings warrant further studies evaluating noradrenergic medications as treatments for stimulant addiction. PMID:18811678

Conformational entropic maps of functional coupling domains in GPCR activation: A case study with beta2 adrenergic receptor

NASA Astrophysics Data System (ADS)

Liu, Fan; Abrol, Ravinder; Goddard, William, III; Dougherty, Dennis

2014-03-01

Entropic effect in GPCR activation is poorly understood. Based on the recent solved structures, researchers in the GPCR structural biology field have proposed several ``local activating switches'' that consisted of a few number of conserved residues, but have long ignored the collective dynamical effect (conformational entropy) of a domain comprised of an ensemble of residues. A new paradigm has been proposed recently that a GPCR can be viewed as a composition of several functional coupling domains, each of which undergoes order-to-disorder or disorder-to-order transitions upon activation. Here we identified and studied these functional coupling domains by comparing the local entropy changes of each residue between the inactive and active states of the β2 adrenergic receptor from computational simulation. We found that agonist and G-protein binding increases the heterogeneity of the entropy distribution in the receptor. This new activation paradigm and computational entropy analysis scheme provides novel ways to design functionally modified mutant and identify new allosteric sites for GPCRs. The authors thank NIH and Sanofi for funding this project.

Crystal Structures of the β2-Adrenergic Receptor

NASA Astrophysics Data System (ADS)

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

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

Enhanced down regulation of cortical +-propranolol sensitive ( sup 3 H)-DHA binding sites by co-administration of DMI and 5-HT sub 1A partial agonist gepirone

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

Geissler, M.A.; Yocca, F.D.

1990-02-26

The putative interrelationship between the noradrenergic and serotonergic systems has been supported by numerous studies. Recently, Dudley et al. (1989) demonstrated significant down regulation of cortical {beta}-adrenergic receptors by co-administration of desipramine (DMI), a norepinephrine uptake inhibitor, and the full 5-HT{sub 1A} agonist 8-OH-DPAT. To this end, the effects of acute and chronic (4 and 14 day) administration of DMI, gepirone, a selective 5-HT{sub 1A} post-synaptic partial agonist, as well as a combination of the two, on cortical ({plus minus})-propranolol sensitive ({sup 3}H)-DHA binding sites were examined in rats. Down regulation was apparent after 4 and 14 day treatment withmore » DMI. However, this was not the case with gepirone. Of particular importance is the demonstration of a greater magnitude of down regulation with co-administration of a greater magnitude of down regulation with co-administration of DMI and gepirone. These results suggests that alteration in rat cortical ({plus minus})-propranolol sensitive ({sup 3}H)-DHA binding sites by noradrenergic uptake inhibitors can be further modulated by selective partial agonist activity at central 5-HT{sub 1A} postsynaptic receptors. Further data on the co-administration of DMI and BMY 7378 (7,9-dioxo-8-(2-(4-{und o}-methoxyphenylpiperazinyl)ethyl)-8-azaspiro(4,5)decane dihydrochloride), a weak partial agonist at postsynaptic 5-HT{sub 1A} receptors, are also presented.« less

Candida glabrata binds to glycosylated and lectinic receptors on the coronary endothelial luminal membrane and inhibits flow sense and cardiac responses to agonists.

PubMed

Torres-Tirado, David; Knabb, Maureen; Castaño, Irene; Patrón-Soberano, Araceli; De Las Peñas, Alejandro; Rubio, Rafael

2016-01-01

Candida glabrata (CG) is an opportunistic fungal pathogen that initiates infection by binding to host cells via specific lectin-like adhesin proteins. We have previously shown the importance of lectin-oligosaccharide binding in cardiac responses to flow and agonists. Because of the lectinic-oligosaccharide nature of CG binding, we tested the ability of CG to alter the agonist- and flow-induced changes in cardiac function in isolated perfused guinea pig hearts. Both transmission and scanning electron microscopy showed strong attachment of CG to the coronary endothelium, even after extensive washing. CG shifted the coronary flow vs. auricular-ventricular (AV) delay relationship upward, indicating that greater flow was required to achieve the same AV delay. This effect was completely reversed with mannose, partially reversed with galactose and N-acetylgalactosamine, but hyaluronan had no effect. Western blot analysis was used to determine binding of CG to isolated coronary endothelial luminal membrane (CELM) receptors, and the results indicate that flow-sensitive CELM receptors, ANG II type I, α-adrenergic 1A receptor, endothelin-2, and VCAM-1 bind to CG. In addition, CG inhibited agonist-induced effects of bradykinin, angiotensin, and phenylephrine on AV delay, coronary perfusion pressure, and left ventricular pressure. Mannose reversed the inhibitory effects of CG on the agonist responses. These results suggest that CG directly binds to flow-sensitive CELM receptors via lectinic-oligosaccharide interactions with mannose and disrupts the lectin-oligosaccharide binding necessary for flow-induced cardiac responses. Copyright © 2016 the American Physiological Society.

The efficacy of mirabegron additional therapy for lower urinary tract symptoms after treatment with α1-adrenergic receptor blocker monotherapy: prospective analysis of elderly men.

PubMed

Matsuo, Tomohiro; Miyata, Yasuyoshi; Kakoki, Katsura; Yuzuriha, Miki; Asai, Akihiro; Ohba, Kojiro; Sakai, Hideki

2016-07-29

Mirabegron is a β3-adrenoreceptor agonist developed for treatment of overactive bladder (OAB). α1-Adrenergic receptor blockers are effective for lower urinary tract symptoms (LUTS) in male patients. However, the efficacy of mirabegron additional treatment in elderly male patients with persistent male LUTS, especially in OAB after monotherapy with α1-adrenergic blockers, is not fully understood. This study was conducted in male LUTS patients who were ≥ 65 years of age and had persistent OAB symptoms, regardless of whether they took an α1-adrenergic receptor blocker orally. Before and 12 weeks after mirabegron additional therapy (50 mg once daily), we evaluated the efficacy of this treatment using the Overactive Bladder Symptom Score (OABSS) and International Prostate Symptom Score (IPSS), and changes in the maximum flow rate (Qmax) and post-void residual urine volume (PVR). We evaluated patients overall and divided into two groups by age: young-old (from 65 to 74 years old) and old-old (from 75 to 84 years old). Fifty men were enrolled in this study. Mirabegron additional therapy improved the total OABSS, total IPSS, and IPSS-quality of life (QOL) score. The voided volume (VV) and Qmax improved after treatment in patients overall. However, there was no significant change in PVR. The total OABSS, total IPSS, and IPSS-QOL score significantly improved in both of the young-old and old-old groups. However, a significant increasing of VV was detected in the young-old group. There were no significant differences in the Qmax or PVR in either group. Mirabegron additional therapy was effective for male patients whose persistent LUTS and particularly OAB was not controlled with α1-adrenergic receptor blocker monotherapy, and mirabegron did not have negative effects on voiding function. Additionally, mirabegron additional therapy was considered effective regardless of patient age. Trial registration number (TRN) trial registration number (TRN) and date of registration: ISRCTN16759097 in July 8, 2016.

Maternal separation diminishes α-adrenergic receptor density and function in renal vasculature from male Wistar-Kyoto rats.

PubMed

Loria, Analia S; Osborn, Jeffrey L

2017-07-01

Adult rats exposed to maternal separation (MatSep) are normotensive but display lower glomerular filtration rate and increased renal neuroadrenergic drive. The aim of this study was to determine the renal α-adrenergic receptor density and the renal vascular responsiveness to adrenergic stimulation in male rats exposed to MatSep. In addition, baroreflex sensitivity was assessed to determine a component of neural control of the vasculature. Using tissue collected from 4-mo-old MatSep and control rats, α 1 -adrenergic receptors (α 1 -ARs) were measured in renal cortex and isolated renal vasculature using receptor binding assay, and the α-AR subtype gene expression was determined by RT-PCR. Renal cortical α 1 -AR density was similar between MatSep and control tissues (B max = 44 ± 1 vs. 42 ± 2 fmol/mg protein, respectively); however, MatSep reduced α 1 -AR density in renal vasculature (B max = 47 ± 4 vs. 62 ± 4 fmol/mg protein, P < 0.05, respectively). In a separate group of rats, the pressor, bradycardic, and renal vascular constrictor responses to acute norepinephrine injection (NE, 0.03-0.25 μg/μl) were determined under anesthesia. Attenuated NE-induced renal vasoconstriction was observed in rats exposed to MatSep compared with control ( P < 0.05). A third group of rats was infused at steady state with the α 1 agonist phenylephrine (10 μg/min iv) and vasodilator sodium nitroprusside (5 μg/min iv). The difference between the change in heart rate/mean arterial pressure slopes was indicative of reduced baroreflex sensitivity in MatSep vs. control rats (-0.45 ± 0.04 vs. -0.95 ± 0.07 beats·min -1 ·mmHg -1 , P < 0.05). These data support the notion that reduced α-adrenergic receptor expression and function in the renal vasculature could develop secondary to MatSep-induced overactivation of the renal neuroadrenergic tone. Copyright © 2017 the American Physiological Society.

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.

Acute regulation of plasma leptin by isoprenaline in lean and obese fasted subjects.

PubMed

Baynes, K C R; Nicholas, M D; Shojaee-Moradie, F; Umpleby, A M; Giannoulis, M G

2006-07-01

In human obesity, there is some evidence for impaired adrenergic sensitivity with respect to catecholamine-induced lipolysis. The beta-adrenoceptor agonist isoprenaline has been shown to suppress plasma leptin levels in lean humans in vivo. We hypothesized that a reduced adrenergic sensitivity in obese humans would result in impaired suppression of leptin secretion. Eight obese [Ob, body mass index (BMI) = 33.3 kg/m2] and seven lean (Ln, BMI = 21.8 kg/m2) men were studied after an overnight fast. Intravenous isoprenaline infusion was initiated at a rate of 8 ng/kg/min, titrated up to 24 ng/kg/min over 30 min and continued at this rate for a further 120 min with continuous electrocardiogram monitoring. Baseline fasting plasma leptin was higher in obese compared with lean subjects (Ob 12.2 +/- 1.8, Ln 2.6 +/- 0.6 ng/ml, p < 0.05 unpaired t-test). Baseline fasting glycerol as a measure of lipolysis was similar in both groups (Ob 62.9 +/- 7.6, Ln 42.4 +/- 8.9 micromol/l) and increased from baseline to 150 min by equivalent amounts (Ob +66.9%, Ln +81.2%, p = NS). Plasma leptin decreased from baseline to 150 min with similar relative changes in both groups (Ob -29.2%, Ln -27.8%). Obese subjects show a similar lipolytic and leptin response to acute isoprenaline infusion compared with lean subjects. Impaired beta-adrenergic-induced inhibition of leptin secretion does not appear to contribute to hyperleptinaemia in obese human subjects.

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.

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.

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.

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

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

Functional distribution of Ca2+-coupled P2 purinergic receptors among adrenergic and noradrenergic bovine adrenal chromaffin cells.

PubMed

Tomé, Angelo R; Castro, Enrique; Santos, Rosa M; Rosário, Luís M

2007-06-14

Adrenal chromaffin cells mediate acute responses to stress through the release of epinephrine. Chromaffin cell function is regulated by several receptors, present both in adrenergic (AD) and noradrenergic (NA) cells. Extracellular ATP exerts excitatory and inhibitory actions on chromaffin cells via ionotropic (P2X) and metabotropic (P2Y) receptors. We have taken advantage of the actions of the purinergic agonists ATP and UTP on cytosolic free Ca2+ concentration ([Ca2+]i) to determine whether P2X and P2Y receptors might be asymmetrically distributed among AD and NA chromaffin cells. The [Ca2+]i and the [Na+]i were recorded from immunolabeled bovine chromaffin cells by single-cell fluorescence imaging. Among the ATP-sensitive cells ~40% did not yield [Ca2+]i responses to ATP in the absence of extracellular Ca2+ (Ca2+o), indicating that they expressed P2X receptors and did not express Ca2+- mobilizing P2Y receptors; the remainder expressed Ca2+-mobilizing P2Y receptors. Relative to AD-cells approximately twice as many NA-cells expressed P2X receptors while not expressing Ca2+- mobilizing P2Y receptors, as indicated by the proportion of cells lacking [Ca2+]i responses and exhibiting [Na+]i responses to ATP in the absence and presence of Ca2+o, respectively. The density of P2X receptors in NA-cells appeared to be 30-50% larger, as suggested by comparing the average size of the [Na+]i and [Ca2+]i responses to ATP. Conversely, approximately twice as many AD-cells expressed Ca2+-mobilizing P2Y receptors, and they appeared to exhibit a higher (~20%) receptor density. UTP raised the [Ca2+]i in a fraction of the cells and did not raise the [Na+]i in any of the cells tested, confirming its specificity as a P2Y agonist. The cell density of UTP-sensitive P2Y receptors did not appear to vary among AD- and NA-cells. Although neither of the major purinoceptor types can be ascribed to a particular cell phenotype, P2X and Ca2+-mobilizing P2Y receptors are preferentially located to noradrenergic and adrenergic chromaffin cells, respectively. ATP might, in addition to an UTP-sensitive P2Y receptor, activate an UTP-insensitive P2Y receptor subtype. A model for a short-loop feedback interaction is presented whereby locally released ATP acts upon P2Y receptors in adrenergic cells, inhibiting Ca2+ influx and contributing to terminate evoked epinephrine secretion.

Fatty acid oxidation is required for active and quiescent brown adipose tissue maintenance and thermogenic programing.

PubMed

Gonzalez-Hurtado, Elsie; Lee, Jieun; Choi, Joseph; Wolfgang, Michael J

2018-01-01

To determine the role of fatty acid oxidation on the cellular, molecular, and physiologic response of brown adipose tissue to disparate paradigms of chronic thermogenic stimulation. Mice with an adipose-specific loss of Carnitine Palmitoyltransferase 2 (Cpt2 A-/- ), that lack mitochondrial long chain fatty acid β-oxidation, were subjected to environmental and pharmacologic interventions known to promote thermogenic programming in adipose tissue. Chronic administration of β3-adrenergic (CL-316243) or thyroid hormone (GC-1) agonists induced a loss of BAT morphology and UCP1 expression in Cpt2 A-/- mice. Fatty acid oxidation was also required for the browning of white adipose tissue (WAT) and the induction of UCP1 in WAT. In contrast, chronic cold (15 °C) stimulation induced UCP1 and thermogenic programming in both control and Cpt2 A-/- adipose tissue albeit to a lesser extent in Cpt2 A-/- mice. However, thermoneutral housing also induced the loss of UCP1 and BAT morphology in Cpt2 A-/- mice. Therefore, adipose fatty acid oxidation is required for both the acute agonist-induced activation of BAT and the maintenance of quiescent BAT. Consistent with this data, Cpt2 A-/- BAT exhibited increased macrophage infiltration, inflammation and fibrosis irrespective of BAT activation. Finally, obese Cpt2 A-/- mice housed at thermoneutrality exhibited a loss of interscapular BAT and were refractory to β3-adrenergic-induced energy expenditure and weight loss. Mitochondrial long chain fatty acid β-oxidation is critical for the maintenance of the brown adipocyte phenotype both during times of activation and quiescence. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

Function of beta 2-adrenergic receptors in chronic localized myalgia.

PubMed

Maekawa, Kenji; Kuboki, Takuo; Inoue, Eitoku; Inoue-Minakuchi, Mami; Suzuki, Koji; Yatani, Hirofumi; Clark, Glenn T

2003-01-01

To investigate alteration of beta 2-adrenergic receptor (beta 2 AR) function in chronic localized myalgia subjects by evaluating levels of the beta 2 AR second messenger, cyclic adenosine monophosphate (cAMP), in mononuclear cells after beta AR-agonist stimulation. Eleven chronic localized myalgia subjects and 21 matched healthy controls participated in this study. Peripheral blood (30 cc) was drawn from the subjects' anterocubital vein. Mononuclear cells were isolated from the total blood by using the Ficoll-Hypaque gradient technique. Basal and stimulated intracellular cAMP levels were determined by enzyme immunoassay using a commercially available kit. Aliquots of 5 x 10(6) cells were incubated with or without stimulation of the beta AR-agonist isoproterenol for 5 minutes. Five different concentrations of isoproterenol (10(-3) M to 10(-7) M) were utilized. cAMP levels in both groups were tested statistically by a 2-way repeated-measures ANOVA with 2 predictors, group difference and isoproterenol concentration difference. As with isoproterenol stimulation, the cAMP responses to forskolin, which activates adenylyl cyclase directly and produces cAMP, bypassing the cell surface receptors were also measured. The basal cAMP levels in both groups (myalgia: 0.33 +/- 0.02 pmol/5 x 10(6) cells; control: 0.43 +/- 0.10 pmol/5 x 10(6) cells) were almost identical, and isoproterenol-produced cAMP levels increased dose-dependently in both groups. No significant differences in the mean cAMP levels were observed between the groups (P = .909). Significant increases were observed according to the isoproterenol concentration increase (P < .0001). The cAMP responses to forskolin stimulation also showed no significant group difference (P = .971). These results suggest that beta 2 AR function is not different between localized myalgia subjects and healthy individuals.

α-adrenergic agonist brimonidine control of experimentally induced myopia in guinea pigs: A pilot study.

PubMed

Liu, Yan; Wang, Yuexin; Lv, Huibin; Jiang, Xiaodan; Zhang, Mingzhou; Li, Xuemin

2017-01-01

To investigate the efficacy of α-adrenergic agonist brimonidine either alone or combined with pirenzepine for inhibiting progressing myopia in guinea pig lens-myopia-induced models. Thirty-six guinea pigs were randomly divided into six groups: Group A received 2% pirenzepine, Group B received 0.2% brimonidine, Group C received 0.1% brimonidine, Group D received 2% pirenzepine + 0.2% brimonidine, Group E received 2% pirenzepine + 0.1% brimonidine, and Group F received the medium. Myopia was induced in the right eyes of all guinea pigs using polymethyl methacrylate (PMMA) lenses for 3 weeks. Eye drops were administered accordingly. Intraocular pressure was measured every day. Refractive error and axial length measurements were performed once a week. The enucleated eyeballs were removed for hematoxylin and eosin (H&E) and Van Gieson (VG) staining at the end of the study. The lens-induced myopia model was established after 3 weeks. Treatment with 0.1% brimonidine alone and 0.2% brimonidine alone was capable of inhibiting progressing myopia, as shown by the better refractive error (p=0.024; p=0.006) and shorter axial length (p=0.005; p=0.0017). Treatment with 0.1% brimonidine and 0.2% brimonidine combined with 2% pirenzepine was also effective in suppressing progressing refractive error (p=0.016; p=0.0006) and axial length (p=0.017; p=0.0004). The thickness of the sclera was kept stable in all groups except group F; the sclera was much thinner in the lens-induced myopia eyes compared to the control eyes. Treatment with 0.1% brimonidine alone and 0.2% brimonidine alone, as well as combined with 2% pirenzepine, was effective in inhibiting progressing myopia. The result indicates that intraocular pressure elevation is possibly a promising mechanism and potential treatment for progressing myopia.

Reciprocal modulation of helper Th1 and Th17 cells by the β2-adrenergic receptor agonist drug terbutaline.

PubMed

Carvajal Gonczi, Catalina M; Tabatabaei Shafiei, Mahdieh; East, Ashley; Martire, Erika; Maurice-Ventouris, Meagane H I; Darlington, Peter J

2017-09-01

Catecholamine hormones are powerful regulators of the immune system produced by the sympathetic nervous system (SNS). They regulate the adaptive immune system by altering T-cell differentiation into T helper (Th) 1 and Th2 cell subsets, but the effect on Th17 cells is not known. Th17 cells, defined, in part, by chemokine receptor CCR6 and cytokine interleukin (IL)-17A, are crucial for mediating certain pathogen-specific responses and are linked with several autoimmune diseases. We demonstrated that a proportion of human Th17 cells express beta 2-adrenergic receptor (β2AR), a G protein-coupled receptor that responds to catecholamines. Activation of peripheral blood mononuclear cells, which were obtained from venous blood drawn from healthy volunteers, with anti-cluster of differentiation 3 (CD3) and anti-CD28 and with a β2-agonist drug, terbutaline (TERB), augmented IL-17A levels (P < 0.01) in the majority of samples. TERB reduced interferon gamma (IFNγ) indicating that IL-17A and IFNγ are reciprocally regulated. Similar reciprocal regulation was observed with dbcAMP. Proliferation of Th cells was monitored by carboxyfluorescein diacetate N-succinimidyl ester labeling and flow cytometry with antibody staining for CD3 and CD4. TERB increased proliferation by a small but significant margin (P < 0.001). Next, Th17 cells (CD4 + CXCR3 - CCR6 + ) were purified using an immunomagnetic positive selection kit, which removes all other mononuclear cells. TERB increased IL-17A from purified Th17 cells, which argues that TERB acts directly on Th17 cells. Thus, hormone signals from the SNS maintain a balance of Th cells subtypes through the β2AR. © 2017 Federation of European Biochemical Societies.

Systematic literature review of clinical trials evaluating pharmacotherapy for overactive bladder in elderly patients: An assessment of trial quality.

PubMed

Kistler, Kristin D; Xu, Yingxin; Zou, Kelly H; Ntanios, Fady; Chapman, Douglass S; Luo, Xuemei

2018-01-01

Overactive bladder (OAB) disproportionately affects older-aged adults, yet most randomized controlled trials (RCTs) underrepresent patients ≥65. This systematic literature review (SLR) identified RCTs evaluating β-3 adrenergic agonists or muscarinic antagonists in elderly patients with OAB, and compared study quality across trials. MEDLINE ® , Embase ® , and Cochrane Collaboration Central Register of Clinical Trials databases were searched from inception through April 28, 2015 to identify published, peer-reviewed RCT reports evaluating β-3 adrenergic agonists or muscarinic antagonists in elderly OAB patients (either ≥65 years or study-described as "elderly"). To assess study quality of RCT reports, we focused on internal/external validity, assessed via two scales: the validated Effective Public Health Practice Project [EPHPP]): Quality Assessment Tool for Quantitative Studies, and a tool commissioned by the Agency for Healthcare Research and Quality (AHRQ). Database searches yielded 1380 records that were then screened according to predefined inclusion/exclusion criteria. We included eight papers meeting study criteria. Despite scientific community efforts to improve RCT reporting standards, published reports still include incomplete and inconsistent reporting-of subject attrition, baseline patient characteristics, inclusion/exclusion criteria, and other important details. Only three of the eight OAB RCTs in this review received quality ratings of Strong (EPHPP) or Fair (AHRQ) and were multicenter with large samples. Despite the prevalence of OAB among older age individuals, relatively few RCTs evaluate OAB treatments explicitly among elderly subjects. The findings from this quality assessment suggest some areas for improvement in both conduct and reporting of future RCTs assessing OAB treatment in elderly. © 2017 Wiley Periodicals, Inc.

Role of alpha- and beta-adrenergic receptors in cardiomyocyte differentiation from murine-induced pluripotent stem cells.

PubMed

Li, Xiao-Li; Zeng, Di; Chen, Yan; Ding, Lu; Li, Wen-Ju; Wei, Ting; Ou, Dong-Bo; Yan, Song; Wang, Bin; Zheng, Qiang-Sun

2017-02-01

Induced pluripotent stem cell (iPSC)-derived cardiomyocytes are a promising source of cells for regenerative heart disease therapies, but progress towards their use has been limited by their low differentiation efficiency and high cellular heterogeneity. Previous studies have demonstrated expression of adrenergic receptors (ARs) in stem cells after differentiation; however, roles of ARs in fate specification of stem cells, particularly in cardiomyocyte differentiation and development, have not been characterized. Murine-induced pluripotent stem cells (miPSCs) were cultured in hanging drops to form embryoid bodies, cells of which were then differentiated into cardiomyocytes. To determine whether ARs regulated miPSC differentiation into cardiac lineages, effects of the AR agonist, epinephrine (EPI), on miPSC differentiation and underlying signalling mechanisms, were evaluated. Treatment with EPI, robustly enhanced miPSC cardiac differentiation, as indicated by increased expression levels of cardiac-specific markers, GATA4, Nkx2.5 and Tnnt2. Although β-AR signalling is the foremost signalling pathway in cardiomyocytes, EPI-enhanced cardiac differentiation depended more on α-AR signalling than β-AR signalling. In addition, selective activation of α 1 -AR signalling with specific agonists induced vigorous cardiomyocyte differentiation, whereas selective activation of α 2 - or β-AR signalling induced no or less differentiation, respectively. EPI- and α 1 -AR-dependent cardiomyocyte differentiation from miPSCs occurred through specific promotion of CPC proliferation via the MEK-ERK1/2 pathway and regulation of miPS cell-cycle progression. These results demonstrate that activation of ARs, particularly of α 1 -ARs, promoted miPSC differentiation into cardiac lineages via MEK-ERK1/2 signalling. © 2016 John Wiley & Sons Ltd.

Effects of fenoterol on ventilatory responses to hypoxia and hypercapnia in normal subjects.

PubMed Central

Yoshiike, Y.; Suzuki, S.; Watanuki, Y.; Okubo, T.

1995-01-01

BACKGROUND--The effects of beta 2 adrenergic agonists on chemoreceptors remain controversial. This study was designed to examine whether fenoterol, a beta 2 adrenergic agonist, increases the ventilatory responses to hypercapnia (HCVR) and hypoxia (HVR) in normal subjects. METHODS--HCVR was tested with a rebreathing method and HVR was examined with a progressive isocapnic hypoxic method in 11 normal subjects. Both HCVR and HVR were assessed by the slope of occlusion pressure (P0.1) or ventilation (VE) plotted against end tidal carbon dioxide pressure and arterial oxygen saturation, respectively. Respiratory muscle strength, spirometric values and lung volume were measured. After a single oral administration of 5 mg fenoterol or placebo HCVR and HVR were evaluated. RESULTS--Fenoterol treatment did not change the specific airway conductance or forced expiratory volume in one second. Respiratory muscle strength did not change. Fenoterol increased the slope of the HCVR of both P0.1 (from 0.251 (0.116) to 0.386 (0.206) kPa/kPa, average increase 71%) and VE (from 10.7 (3.4) to 15.1 (4.2) l/min/kPa, average increase 52%), and shifted the response curves to higher values. For the HVR fenoterol increased the slopes of both P0.1 and VE (from -4.06 (2.00) x 10(-3) to -7.99 (4.29) x 10(-3) kPa/%, an average increase of 83%, and from -0.221 (0.070) to -0.313 (0.112) l/min/%, a 44.5% increase, respectively), and shifted the response curves to higher values. CONCLUSION--Acute administration of fenoterol increases the ventilatory responses to both hypercapnia and hypoxia in normal subjects. PMID:7701451

Differential acute and chronic response of protein kinase C in cultured neonatal rat heart myocytes to alpha 1-adrenergic and phorbol ester stimulation.

PubMed

Henrich, C J; Simpson, P C

1988-12-01

Both alpha 1-adrenergic agonists (e.g. norepinephrine, NE*) and tumor-promoting phorbol esters (e.g. phorbol myristate acetate, PMA) are known to activate protein kinase C (PKC) (Abdel-Latif, 1986, Niedel and Blackshear, 1986). However, alpha 1 agonists and PMA produce very different effects on cardiac function (see Simpson, 1985; Benfey, 1987; Meidell et al., 1986; Leatherman et al., 1987; Yuan et al., 1987; for examples). PKC activation in heart cells has been studied only for PMA treated perfused heart (Yuan et al., 1987). Therefore, acute activation and chronic regulation of PKC by NE and PMA were compared in cultured neonatal rat heart myocytes. NE acutely and transiently activated PKC, as measured by translocation of PKC activity to the cell particulate fraction (Niedel and Blackshear, 1986). Particulate PKC activity peaked at 23% of total after NE for 30 s, as compared with 8% for control (P less than 0.001). By contrast, acute PKC activation by PMA was more pronounced and persistent, with particulate PKC activity 62% of total at 5 min (P less than 0.001). Calcium/lipid-independent kinase activity increased acutely with PMA, but not with NE. Chronic treatment with NE (24 to 48 h) increased total per cell PKC activity and 3H-phorbol dibutyrate (PDB) binding sites, an index of the number of PKC molecules (Niedel and Blackshear, 1986), by 30 to 60% over control (all P less than 0.05 to 0.01). In contrast with NE, chronic treatment with PMA down-regulated PKC, reducing total per cell PKC activity and 3H-PDB binding sites to 3% and 12% of control, respectively (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Neural correlate of resting-state functional connectivity under α2 adrenergic receptor agonist, medetomidine.

PubMed

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

2014-01-01

Correlative fluctuations in functional MRI (fMRI) signals across the brain at rest have been taken as a measure of functional connectivity, but the neural basis of this resting-state MRI (rsMRI) signal is not clear. Previously, we found that the α2 adrenergic agonist, medetomidine, suppressed the rsMRI correlation dose-dependently but not the stimulus evoked activation. To understand the underlying electrophysiology and neurovascular coupling, which might be altered due to the vasoconstrictive nature of medetomidine, somatosensory evoked potential (SEP) and resting electroencephalography (EEG) were measured and correlated with corresponding BOLD signals in rat brains under three dosages of medetomidine. The SEP elicited by electrical stimulation to both forepaws was unchanged regardless of medetomidine dosage, which was consistent with the BOLD activation. Identical relationship between the SEP and BOLD signal under different medetomidine dosages indicates that the neurovascular coupling was not affected. Under resting state, EEG power was the same but a depression of inter-hemispheric EEG coherence in the gamma band was observed at higher medetomidine dosage. Different from medetomidine, both resting EEG power and BOLD power and coherence were significantly suppressed with increased isoflurane level. Such reduction was likely due to suppressed neural activity as shown by diminished SEP and BOLD activation under isoflurane, suggesting different mechanisms of losing synchrony at resting-state. Even though, similarity between electrophysiology and BOLD under stimulation and resting-state implicates a tight neurovascular coupling in both medetomidine and isoflurane. Our results confirm that medetomidine does not suppress neural activity but dissociates connectivity in the somatosensory cortex. The differential effect of medetomidine and its receptor specific action supports the neuronal origin of functional connectivity and implicates the mechanism of its sedative effect. © 2013. Published by Elsevier Inc. All rights reserved.

Increased Mortality in Groups of Cattle Administered the β-Adrenergic Agonists Ractopamine Hydrochloride and Zilpaterol Hydrochloride

PubMed Central

Loneragan, Guy H.; Thomson, Daniel U.; Scott, H. Morgan

2014-01-01

The United States Food and Drug Administration (FDA) approved two β-adrenergic agonists (βAA) for in-feed administration to cattle fed in confinement for human consumption. Anecdotal reports have generated concern that administration of βAA might be associated with an increased incidence of cattle deaths. Our objectives, therefore, were to a) quantify the association between βAA administration and mortality in feedlot cattle, and b) explore those variables that may confound or modify this association. Three datasets were acquired for analysis: one included information from randomized and controlled clinical trials of the βAA ractopamine hydrochloride, while the other two were observational data on zilpaterol hydrochloride administration to large numbers of cattle housed, fed, and cared for using routine commercial production practices in the U.S. Various population and time at-risk models were developed to explore potential βAA relationships with mortality, as well as the extent of confounding and effect modification. Measures of effect were relatively consistent across datasets and models in that the cumulative risk and incidence rate of death was 75 to 90% greater in animals administered the βAA compared to contemporaneous controls. During the exposure period, 40 to 50% of deaths among groups administered the βAA were attributed to administration of the drug. None of the available covariates meaningfully confounded the relationship between βAA and increased mortality. Only month of slaughter, presumably a proxy for climate, consistently modified the effect in that the biological association was generally greatest during the warmer months of the year. While death is a rare event in feedlot cattle, the data reported herein provide compelling evidence that mortality is nevertheless increased in response to administration of FDA-approved βAA and represents a heretofore unquantified adverse drug event. PMID:24621596

p38 Mitogen-Activated Protein Kinase-γ Inhibition by Long-Acting β2 Adrenergic Agonists Reversed Steroid Insensitivity in Severe Asthma

PubMed Central

Mercado, Nicholas; To, Yasuo; Kobayashi, Yoshiki; Adcock, Ian M.; Barnes, Peter J.

2011-01-01

Corticosteroid insensitivity (CI) is a major barrier to treating severe asthma. Despite intensive research, the molecular mechanism of CI remains uncertain. The aim of this study was to determine abnormality in corticosteroid action in severe asthma and to identify the molecular mechanism of the long-acting β2-adrenergic agonists (LABAs) formoterol and salmeterol on restoration of corticosteroid sensitivity in severe asthma in vitro. Peripheral blood mononuclear cells (PBMCs) were obtained from 16 subjects with severe corticosteroid-insensitive asthma, 6 subjects with mild corticosteroid-sensitive asthma, and 11 healthy volunteers. Corticosteroid (dexamethasone) sensitivity was determined on tumor necrosis factor-α (TNF-α)-induced interleukin (IL)-8 production. Glucocorticoid receptor (GR) phosphorylation and kinase phosphorylation were evaluated by immunoprecipitation-Western blotting analysis and kinase phosphorylation array in IL-2/IL-4-treated corticosteroid insensitive model in PBMCs. In vitro corticosteroid sensitivity on TNF-α-induced IL-8 production was significantly lower in patients with severe asthma than in healthy volunteers and patients with mild asthma. This CI seen in severe asthma was associated with reduced GR nuclear translocation and with hyperphosphorylation of GR, which were reversed by LABAs. In IL-2/IL-4-treated PBMCs, LABAs inhibited phosphorylation of Jun-NH2-terminal kinase and p38 mitogen-activated protein kinase-γ (p38MAPK-γ) as well as GR. In addition, cells with p38MAPK-γ knockdown by RNA interference did not develop CI in the presence of IL-2/IL-4. Furthermore, p38MAPK-γ protein expression was up-regulated in PBMCs from some patients with severe asthma. In conclusion, p38 MAPK-γ activation impairs corticosteroid action and p38 MAPK-γ inhibition by LABAs has potential for the treatment of severe asthma. PMID:21917909

Palmitoylation regulates intracellular trafficking of β2 adrenergic receptor/arrestin/phosphodiesterase 4D complexes in cardiomyocytes.

PubMed

Liu, Ruijie; Wang, Dayong; Shi, Qian; Fu, Qin; Hizon, Steven; Xiang, Yang K

2012-01-01

β(2) adrenergic receptor (β(2)AR) is a prototypical G-protein coupled receptor that stimulates the classic cAMP-protein kinase A (PKA) signaling pathway. Recent studies indicate that the cAMP-PKA activities are spatiotemporally regulated in part due to dynamic association of β(2)AR with phosphodiesterase 4D (PDE4D), a group of cAMP degradation enzymes. Here, we demonstrate that in cardiomyocytes, palmitoylation of β(2)AR, the covalent acylation of cysteine residue 341, plays a critical role in shaping subcellular cAMP-PKA activities in cardiomyocytes via regulating β(2)AR association with arrestin/PDE4D. Replacing cysteine 341 on β(2)AR with alanine (C341A) leads to an impaired binding to β arrestin 2. Surprisingly, the C341A mutant is able to internalize via an arrestin-independent pathway at saturated concentration of agonist stimulation; the internalization becomes caveolae-dependent and requires dynamin GTPase. However, the impaired binding to β arrestin 2 also leads to an impaired recruitment of PDE4D to the C341A mutant. Thus, the mutant C341A β(2)AR is transported alone from the plasma membrane to the endosome without recruiting PDE4D. This alteration leads to an enhanced cytoplasmic cAMP signal for PKA activation under β(2)AR stimulation. Functionally, Mutation of the C341 residue or inhibition of palmitoylation modification of β(2)AR enhances the receptor-induced PKA activities in the cytoplasm and increases in myocyte contraction rate. Our data reveal a novel function of palmitoylation in shaping subcellular cAMP-PKA signaling in cardiomyocytes via modulating the recruitment of β arrestin 2-PDE4D complexes to the agonist-stimulated β(2)AR.

Palmitoylation Regulates Intracellular Trafficking of β2 Adrenergic Receptor/Arrestin/Phosphodiesterase 4D Complexes in Cardiomyocytes

PubMed Central

Liu, Ruijie; Wang, Dayong; Shi, Qian; Fu, Qin; Hizon, Steven; Xiang, Yang K.

2012-01-01

β2 adrenergic receptor (β2AR) is a prototypical G-protein coupled receptor that stimulates the classic cAMP-protein kinase A (PKA) signaling pathway. Recent studies indicate that the cAMP-PKA activities are spatiotemporally regulated in part due to dynamic association of β2AR with phosphodiesterase 4D (PDE4D), a group of cAMP degradation enzymes. Here, we demonstrate that in cardiomyocytes, palmitoylation of β2AR, the covalent acylation of cysteine residue 341, plays a critical role in shaping subcellular cAMP-PKA activities in cardiomyocytes via regulating β2AR association with arrestin/PDE4D. Replacing cysteine 341 on β2AR with alanine (C341A) leads to an impaired binding to β arrestin 2. Surprisingly, the C341A mutant is able to internalize via an arrestin-independent pathway at saturated concentration of agonist stimulation; the internalization becomes caveolae-dependent and requires dynamin GTPase. However, the impaired binding to β arrestin 2 also leads to an impaired recruitment of PDE4D to the C341A mutant. Thus, the mutant C341A β2AR is transported alone from the plasma membrane to the endosome without recruiting PDE4D. This alteration leads to an enhanced cytoplasmic cAMP signal for PKA activation under β2AR stimulation. Functionally, Mutation of the C341 residue or inhibition of palmitoylation modification of β2AR enhances the receptor-induced PKA activities in the cytoplasm and increases in myocyte contraction rate. Our data reveal a novel function of palmitoylation in shaping subcellular cAMP-PKA signaling in cardiomyocytes via modulating the recruitment of β arrestin 2-PDE4D complexes to the agonist-stimulated β2AR. PMID:22912718

Activation of the Cystic Fibrosis Transmembrane Conductance Regulator by the Flavonoid Quercetin

PubMed Central

Pyle, Louise C.; Fulton, Jennifer C.; Sloane, Peter A.; Backer, Kyle; Mazur, Marina; Prasain, Jeevan; Barnes, Stephen; Clancy, J. P.; Rowe, Steven M.

2010-01-01

Therapies to correct the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) folding defect require sensitive methods to detect channel activity in vivo. The β2 adrenergic receptor agonists, which provide the CFTR stimuli commonly used in nasal potential difference assays, may not overcome the channel gating defects seen in ΔF508 CFTR after plasma membrane localization. In this study, we identify an agent, quercetin, that enhances the detection of surface ΔF508 CFTR, and is suitable for nasal perfusion. A screen of flavonoids in CFBE41o− cells stably transduced with ΔF508 CFTR, corrected to the cell surface with low temperature growth, revealed that quercetin stimulated an increase in the short-circuit current. This increase was dose-dependent in both Fisher rat thyroid and CFBE41o− cells. High concentrations inhibited Cl− conductance. In CFBE41o− airway cells, quercetin (20 μg/ml) activated ΔF508 CFTR, whereas the β2 adrenergic receptor agonist isoproterenol did not. Quercetin had limited effects on cAMP levels, but did not produce detectable phosphorylation of the isolated CFTR R-domain, suggesting an activation independent of channel phosphorylation. When perfused in the nares of Cftr+ mice, quercetin (20 μg/ml) produced a hyperpolarization of the potential difference that was absent in Cftr−/− mice. Finally, quercetin-induced, dose-dependent hyperpolarization of the nasal potential difference was also seen in normal human subjects. Quercetin activates CFTR-mediated anion transport in respiratory epithelia in vitro and in vivo, and may be useful in studies intended to detect the rescue of ΔF508 CFTR by nasal potential difference. PMID:20042712

Modulation of cannabinoid signaling by amygdala α2-adrenergic system in fear conditioning.

PubMed

Nasehi, Mohammad; Zamanparvar, Majid; Ebrahimi-Ghiri, Mohaddeseh; Zarrindast, Mohammad-Reza

2016-03-01

The noradrenergic system plays a critical role in the modulation of emotional state, primarily related to anxiety, arousal, and stress. Growing evidence suggests that the endocannabinoid system mediates stress responses and emotional homeostasis, in part, by targeting noradrenergic circuits. In addition, there is an interaction between the cannabinoid and noradrenergic system that has significant functional and behavioral implications. Considering the importance of these systems in forming memories for fearful events, we have investigated the involvement of basolateral amygdala (BLA) α2-adrenoceptors on ACPA (as selective cannabinoid CB1 agonist)-induced inhibition of the acquisition of contextual and auditory conditioned fear. A contextual and auditory fear conditioning apparatus for assess fear memory in adult male NMRI mice was used. Pre-training, intraperitoneal administration of ACPA decreased the percentage freezing time in contextual (at doses of 0.05 and 0.1mg/kg) and auditory (at dose of 0.1 mg/kg) in the fear conditioning task, indicating memory acquisition deficit. The same result was observed with intra-BLA microinjection of clonidine (0.001-0.5 μg/mouse, for both memories), as α2-adrenoceptor agonist and yohimbine (at doses of 0.005 and 0.05 for contextual and at dose of 0.05 μg/mouse for auditory fear memory), as α2-adrenoceptor antagonist. In addition, intra-BLA microinjection of clonidine (0.0005 μg/mouse) did not alter ACPA response in both conditions, while the same dose of yohimbine potentiated ACPA response at the lower dose on contextual fear memory. It is concluded that BLA α2-adrenergic receptors may be involved in context- but not tone-dependent fear memory impairment induced by activation of CB1 receptors. Copyright © 2015. Published by Elsevier B.V.

Time-dependent effect of clonidine on microvascular permeability during endotoxemia.

PubMed

Schmidt, Karsten; Hernekamp, Jochen Frederick; Philipsenburg, Christoph; Zivkovic, Aleksandar R; Brenner, Thorsten; Hofer, Stefan

2015-09-01

Endothelial leakage with accompanying tissue edema and increased leukocyte adhesion are characteristics of the vascular inflammatory response. Tissue edema formation is a key mechanism in sepsis pathophysiology contributing to impaired tissue oxygenation and the development of shock. Sepsis mortality is directly associated with the severity of these microcirculatory alterations. Dysfunction of the sympathetic nervous system can have deleterious effects in generalized inflammation. This study evaluated the effect of the adrenergic alpha 2 agonist clonidine on microvascular permeability and leukocyte adhesion during endotoxemia. Macromolecular leakage, leukocyte adhesion, and venular wall shear rate were examined in mesenteric postcapillary venules of rats by using intravital microscopy (IVM). Lipopolysaccharide (LPS) (4mg/kg/h) or equivalent volumes of saline were continuously infused following baseline IVM at 0min. IVM was repeated after 60 and 120min in endotoxemic and nonendotoxemic animals. Clonidine (10μg/kg) was applied as an i.v. bolus. Animals received either (i) saline alone, (ii) clonidine alone, (iii) clonidine 45min prior to LPS, (iv) clonidine 10min prior to LPS, (v) clonidine 30min after LPS, or (vi) LPS alone. Due to nonparametric data distribution, Wilcoxon test and Dunn's multiple comparisons test were used for data analysis. Data were considered statistically significant at p<0.05. LPS significantly increased microvascular permeability and leukocyte adhesion and decreased venular wall shear rate. Clonidine significantly reduced microvascular permeability when applied 45min before or 30min after LPS administration. Leukocyte adhesion and venular wall shear rate were not affected by clonidine during endotoxemia. Clonidine reduces microvascular permeability in endotoxemic animals in a time-dependent manner. Adrenergic alpha 2 agonists might prove beneficial in stabilizing capillary leakage during inflammation. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparative cost evaluation of brand name and generic ophthalmology medications in Ontario.

PubMed

Popovic, Marko; Chan, Clara; Lattanzio, Nisha; El-Defrawy, Sherif; Schlenker, Matthew B

2018-04-01

Medication cost for the same indication can vary considerably and can affect patient compliance. In this comparative cost analysis of commonly prescribed ophthalmology medications, the differences in cost between generic and brand name medications as well as different medications within an individual drug class were evaluated. Eye preparations from the Ontario Drug Benefit Formulary were identified, and further agents commonly prescribed by ophthalmologists were included. The standardized prescription drug cost, which includes the cost of the medication, mark-up, and dispensing cost, was provided by Ontario Shoppers Drug Mart stores in July 2016 for 103 common medications using typical dosages and durations. Based on medication class, the highest and lowest cost medications were antiallergy agents (Zaditor [ketotifen], Vasocon [naphazoline]), antibiotic ophthalmic solutions (Vigamox [moxifloxacin], generic ciprofloxacin), oral antibiotics (Cipro [ciprofloxacin], generic cephalexin), antibiotic ophthalmic ointments (generic erythromycin, Tobrex [tobramycin]), antiviral treatment (Valtrex [oral valacyclovir], Viroptic [topical trifluridine]), blepharitis treatment (Zithromax [oral azithromycin], generic oral tetracycline), beta-adrenergic inhibitors (Timoptic [topical timolol], generic topical timolol), topical prostaglandin analogues (Xalatan [latanoprost], generic travoprost), oral carbonic anhydrase inhibitors (methazolamide, acetazolamide), topical carbonic anhydrase solutions (Trusopt preservative-free [dorzolamide], Azopt [brinzolamide]), topical alpha-adrenergic agonists (Alphagan [brimonidine], generic brimonidine), topical muscarinic agonists (Isopto carpine [pilocarpine], Diocarpine [pilocarpine]), topical combination glaucoma agents (Cosopt [dorzolamide-timolol], generic dorzolamide-timolol), topical lubricants (Lacri-lube, Isopto tears), topical nonsteroidal anti-inflammatory drugs (Acuvail [ketorolac], Ilevro [nepafenac]), and steroids (Durezol [difluprednate], Pred mild [prednisolone]). Substantial cost differences exist between ophthalmology medications of the same class. We encourage ophthalmologists to be aware of the associated costs of the medications they prescribe and to use this information in their decision making. Copyright © 2018 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

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.

Dysfunction of Inflammation-Resolving Pathways Is Associated with Exaggerated Postoperative Cognitive Decline in a Rat Model of the Metabolic Syndrome

PubMed Central

Su, Xiao; Feng, Xiaomei; Terrando, Niccolo; Yan, Yan; Chawla, Ajay; Koch, Lauren G; Britton, Steven L; Matthay, Michael A; Maze, Mervyn

2012-01-01

The cholinergic antiinflammatory pathway (CAP), which terminates in the spleen, attenuates postoperative cognitive decline (PCD) in rodents. Surgical patients with metabolic syndrome exhibit exaggerated and persistent PCD that is reproduced in postoperative rats selectively bred for easy fatigability and that contain all features of metabolic syndrome (low-capacity runners [LCRs]). We compared the CAP and lipoxin A4 (LXA4), another inflammation-resolving pathway in LCR, with its counterpart high-capacity runner (HCR) rats. Isoflurane-anesthetized LCR and HCR rats either underwent aseptic trauma involving tibial fracture (surgery) or not (sham). At postoperative d 3 (POD3), compared with HCR, LCR rats exhibited significantly exaggerated PCD (trace fear conditioning freezing time 43% versus 57%). Separate cohorts were killed at POD3 to collect plasma for LXA4 and to isolate splenic mononuclear cells (MNCs) to analyze CAP signaling, regulatory T cells (Tregs) and M2 macrophages (M2 Mφ). Under lipopolysaccharide (LPS) stimulation, tumor necrosis factor (TNF)-α produced by splenic MNCs was 117% higher in LCR sham and 52% higher in LCR surgery compared with HCR sham and surgery rats; LPS-stimulated TNF-α production could not be inhibited by an α7 nicotinic acetylcholine receptor agonist, whereas inhibition by the β2 adrenergic agonist, salmeterol, was significantly less (−35%) than that obtained in HCR rats. Compared to HCR, sham and surgery LCR rats had reduced β2 adrenergic receptor–expressing T lymphocytes (59%, 44%), Tregs (47%, 54%) and M2 Mφ (45%, 39%); surgical LCR rats’ hippocampal M2 Mφ was 66% reduced, and plasma LXA4 was decreased by 120%. Rats with the metabolic syndrome have ineffective inflammation-resolving mechanisms that represent plausible reasons for the exaggerated and persistent PCD. PMID:23296426

Effects of immunocastration and a β-adrenergic agonist on retail cuts of feedlot finished Nellore cattle.

PubMed

Brigida, D J; Antonelo, D S; Mazon, M R; Nubiato, K E Z; Gómez, J F M; Netto, A S; Leme, P R; Cônsolo, N R B; Pesce, D M C; Silva, S L

2017-12-19

Immunocastration (ImC) has been proposed as an animal welfare-friendly alternative to reduce sexual and aggressive behavior and to increase carcass fat deposition with positive effects on meat quality. The β-adrenergic agonists (β-AA) are known as repartitioning agents that acts increasing lean tissue deposition. The combined use of these technologies can positively affect meat quality and increase retail cuts yield. Thus, this research was conducted to evaluate the combined effects of ImC and β-AA (zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RH)) on retail cuts, bones, and fat trim of feedlot finished Bos indicus (Nellore) cattle. No interaction was observed between sexual condition and diet for any trait. The ImC decreased cold carcass, hindquarter (HQ), forequarter (FQ) and combined brisket, short ribs and flank (BSF) weights. The ImC also showed smaller weights of retail cuts and bones on the HQ and on the FQ than non-castrated (NoC). Fat trim weights did not differ from ImC and NoC. The most of subprimal cuts were heavier in NoC than in ImC. Feeding β-AA did not affect cold carcass weight; however, animals fed ZH had higher weights of HQ and retail cuts in HQ when compared with RH and control (CO) group, with no differences between RH and CO for both traits. The weights of FQ, BSF, retail cuts in FQ, as well as bones and fat trimmings were not affected by β-AA. In summary, ImC decreases carcass and retail cut weights, whereas ZH supplementation leads to an improvement in carcass lean tissue and retail cuts.

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.

Differentiation of human bronchial epithelial cells: role of hydrocortisone in development of ion transport pathways involved in mucociliary clearance.

PubMed

Zaidman, Nathan A; Panoskaltsis-Mortari, Angela; O'Grady, Scott M

2016-08-01

Glucocorticoids strongly influence the mucosal-defense functions performed by the bronchial epithelium, and inhaled corticosteroids are critical in the treatment of patients with inflammatory airway diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis. A common pathology associated with these diseases is reduced mucociliary clearance, a defense mechanism involving the coordinated transport of salt, water, and mucus by the bronchial epithelium, ultimately leading to retention of pathogens and particles in the airways and to further disease progression. In the present study we investigated the role of hydrocortisone (HC) in differentiation and development of the ion transport phenotype of normal human bronchial epithelial cells under air-liquid interface conditions. Normal human bronchial epithelial cells differentiated in the absence of HC (HC0) showed significantly less benzamil-sensitive short-circuit current than controls, as well as a reduced response after stimulation with the selective β2-adrenergic receptor agonist salbutamol. Apical membrane localization of epithelial Na(+) channel α-subunits was similarly reduced in HC0 cells compared with controls, supporting a role of HC in the trafficking and density of Na(+) channels in the plasma membrane. Additionally, glucocorticoid exposure during differentiation regulated the transcription of cystic fibrosis transmembrane conductance regulator and β2-adrenergic receptor mRNAs and appeared to be necessary for the expression of cystic fibrosis transmembrane conductance regulator-dependent anion secretion in response to β2-agonists. HC had no significant effect on surface cell differentiation but did modulate the expression of mucin mRNAs. These findings indicate that glucocorticoids support mucosal defense by regulating critical transport pathways essential for effective mucociliary clearance. Copyright © 2016 the American Physiological Society.

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

Structural insights into μ-opioid receptor activation

PubMed Central

Huang, Weijiao; Manglik, Aashish; Venkatakrishnan, A. J.; Laeremans, Toon; Feinberg, Evan N.; Sanborn, Adrian L.; Kato, Hideaki E.; Livingston, Kathryn E.; Thorsen, Thor S.; Kling, Ralf; Granier, Sébastien; Gmeiner, Peter; Husbands, Stephen M.; Traynor, John R.; Weis, William I.; Steyaert, Jan; Dror, Ron O.; Kobilka, Brian K.

2015-01-01

Summary Activation of the μ-opioid receptor (μOR) is responsible for the efficacy of the most effective analgesics. To understand the structural basis for μOR activation, we obtained a 2.1 Å X-ray crystal structure of the μOR bound to the morphinan agonist BU72 and stabilized by a G protein-mimetic camelid-antibody fragment. The BU72-stabilized changes in the μOR binding pocket are subtle and differ from those observed for agonist-bound structures of the β2 adrenergic receptor (β2AR) and the M2 muscarinic receptor (M2R). Comparison with active β2AR reveals a common rearrangement in the packing of three conserved amino acids in the core of the μOR, and molecular dynamics simulations illustrate how the ligand-binding pocket is conformationally linked to this conserved triad. Additionally, an extensive polar network between the ligand-binding pocket and the cytoplasmic domains appears to play a similar role in signal propagation for all three GPCRs. PMID:26245379

Cardiac β-adrenergic responsiveness of obese Zucker rats: The role of AMPK.

PubMed

Bussey, Carol T; Thaung, Hp Aye; Hughes, Gillian; Bahn, Andrew; Lamberts, Regis R

2018-06-05

What is the central question of the study? What is the main finding and its importance? 1. Is the reduced signalling of AMPK, a key regulator of energy homeostasis in the heart, responsible for the reduced β-adrenergic responsiveness of the heart in obesity? 2. Inhibition of AMPK in isolated hearts prevented the reduced cardiac β-adrenergic responsiveness of obese rats, which was accompanied by reduced phosphorylation of AMPK, a proxy of AMPK activity. This suggests a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart, and that AMPK might be an important target to restore the β-adrenergic responsiveness in the heart in obesity. The obesity epidemic impacts heavily on cardiovascular health, in part due to changes in cardiac metabolism. AMP-activated protein kinase (AMPK) is a key regulator of energy homeostasis in the heart, and is regulated by β-adrenoceptors (AR) under normal conditions. In obesity, chronic sympathetic overactivation leads to impaired cardiac β-AR responsiveness, although it is unclear whether AMPK signalling, downstream of β-AR, contributes to this dysfunction. Therefore, we aimed to determine whether reduced AMPK signalling is responsible for the reduced β-AR responsiveness in obesity. In isolated hearts of lean and obese Zucker rats, we tested β-AR responsiveness to β 1 -AR agonist isoproterenol (ISO, 1 × 10 -10 - 5 × 10 -8  M) in the absence and presence of the AMPK inhibitor compound C (CC, 10 μM). β 1 -AR expression and AMPK phosphorylation were assessed by Western blot. β-Adrenergic responsiveness was reduced in the hearts of obese rats (LogEC50 of ISO-developed pressure dose-response curves: lean -8.53 ± 0.13 vs. obese -8.35 ± 0.10 10 x M; p < 0.05 lean vs. obese, n = 6 per group). This difference was not apparent after AMPK inhibition (LogEC50 of ISO-developed pressure curves: lean CC -8.19 ± 0.12 vs. obese CC 8.17 ± 0.13 10 x M, p > 0.05, n = 6 per group). β 1 -AR expression and AMPK phosphorylation were reduced in hearts of obese rats (AMPK at Thr 172 : lean 1.73 ± 0.17 vs. lean CC 0.81 ± 0.13, and obese 1.18 ± 0.09 vs. obese CC 0.81 ± 0.16 arbitrary units, p < 0.05, n = 6 per group). Thus, a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart exists, and AMPK might be an important target to restore the reduced cardiac β-adrenergic responsiveness in obesity. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Induction of Cardiac Fibrosis by β-Blocker in G Protein-independent and G Protein-coupled Receptor Kinase 5/β-Arrestin2-dependent Signaling Pathways*

PubMed Central

Nakaya, Michio; Chikura, Satsuki; Watari, Kenji; Mizuno, Natsumi; Mochinaga, Koji; Mangmool, Supachoke; Koyanagi, Satoru; Ohdo, Shigehiro; Sato, Yoji; Ide, Tomomi; Nishida, Motohiro; Kurose, Hitoshi

2012-01-01

G-protein coupled receptors (GPCRs) have long been known as receptors that activate G protein-dependent cellular signaling pathways. In addition to the G protein-dependent pathways, recent reports have revealed that several ligands called “biased ligands” elicit G protein-independent and β-arrestin-dependent signaling through GPCRs (biased agonism). Several β-blockers are known as biased ligands. All β-blockers inhibit the binding of agonists to the β-adrenergic receptors. In addition to β-blocking action, some β-blockers are reported to induce cellular responses through G protein-independent and β-arrestin-dependent signaling pathways. However, the physiological significance induced by the β-arrestin-dependent pathway remains much to be clarified in vivo. Here, we demonstrate that metoprolol, a β1-adrenergic receptor-selective blocker, could induce cardiac fibrosis through a G protein-independent and β-arrestin2-dependent pathway. Metoprolol, a β-blocker, increased the expression of fibrotic genes responsible for cardiac fibrosis in cardiomyocytes. Furthermore, metoprolol induced the interaction between β1-adrenergic receptor and β-arrestin2, but not β-arrestin1. The interaction between β1-adrenergic receptor and β-arrestin2 by metoprolol was impaired in the G protein-coupled receptor kinase 5 (GRK5)-knockdown cells. Metoprolol-induced cardiac fibrosis led to cardiac dysfunction. However, the metoprolol-induced fibrosis and cardiac dysfunction were not evoked in β-arrestin2- or GRK5-knock-out mice. Thus, metoprolol is a biased ligand that selectively activates a G protein-independent and GRK5/β-arrestin2-dependent pathway, and induces cardiac fibrosis. This study demonstrates the physiological importance of biased agonism, and suggests that G protein-independent and β-arrestin-dependent signaling is a reason for the diversity of the effectiveness of β-blockers. PMID:22888001

Contractile properties of early human embryonic stem cell-derived cardiomyocytes: beta-adrenergic stimulation induces positive chronotropy and lusitropy but not inotropy.

PubMed

Pillekamp, Frank; Haustein, Moritz; Khalil, Markus; Emmelheinz, Markus; Nazzal, Rewa; Adelmann, Roland; Nguemo, Filomain; Rubenchyk, Olga; Pfannkuche, Kurt; Matzkies, Matthias; Reppel, Michael; Bloch, Wilhelm; Brockmeier, Konrad; Hescheler, Juergen

2012-08-10

Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) provide the unique opportunity to study the very early development of the human heart. The aim of this study was to investigate the effect of calcium and beta-adrenergic stimulation on the contractile properties of early hESC-CMs. Beating clusters containing hESC-CMs were co-cultured in vitro with noncontractile slices of neonatal murine ventricles. After 5-7 days, when beating clusters had integrated morphologically into the damaged tissue, isometric force measurements were performed during spontaneous beating as well as during electrical field stimulation. Spontaneous beating stopped when extracellular calcium ([Ca²⁺](ec)) was removed or after administration of the Ca²⁺ channel blocker nifedipine. During field stimulation at a constant rate, the developed force increased with incremental concentrations of [Ca²⁺](ec). During spontaneous beating, rising [Ca²⁺](ec) increased beating rate and developed force up to a [Ca²⁺](ec) of 2.5 mM. When [Ca²⁺](ec) was increased further, spontaneous beating rate decreased, whereas the developed force continued to increase. The beta-adrenergic agonist isoproterenol induced a dose-dependent increase of the frequency of spontaneous beating; however, it did not significantly change the developed force during spontaneous contractions or during electrical stimulation at a constant rate. Force developed by early hESC-CMs depends on [Ca²⁺](ec) and on the L-type Ca²⁺ channel. The lack of an inotropic reaction despite a pronounced chronotropic response after beta-adrenergic stimulation most likely indicates immaturity of the sarcoplasmic reticulum. For cell-replacement strategies, further maturation of cardiac cells has to be achieved either in vitro before or in vivo after transplantation.

Acute Effect of Hookah Smoking on the Human Coronary Microcirculation

PubMed Central

Nelson, Michael D.; Rezk-Hanna, Mary; Rader, Florian; Mason, O’Neil R.; Tang, Xiu; Shidban, Sarah; Rosenberry, Ryan; Benowitz, Neal L.; Tashkin, Donald P.; Elashoff, Robert M.; Lindner, Jonathan R.; Victor, Ronald G.

2017-01-01

Hookah (water pipe) smoking is a major new understudied epidemic affecting youth. Because burning charcoal is used to heat the tobacco product, hookah smoke delivers not only nicotine but also large amounts of charcoal combustion products, including carbon-rich nanoparticles that constitute putative coronary vasoconstrictor stimuli and carbon monoxide, a known coronary vasodilator. We used myocardial contrast echocardiography perfusion imaging with intravenous lipid shelled microbubbles in young adult hookah smokers to determine the net effect of smoking hookah on myocardial blood flow. In 9 hookah smokers (age 27 – 5 years, mean – SD), we measured myocardial blood flow velocity (β), myocardial blood volume (A), myocardial blood flow (A × β) as well as myocardial oxygen consumption (MVO2) before and immediately after 30 minutes of ad lib hookah smoking. Myocardial blood flow did not decrease with hookah smoking but rather increased acutely (88 – 10 to 120 – 19 a.u./s, mean – SE, p = 0.02), matching a mild increase in MVO2 (6.5 – 0.3 to 7.6 – 0.4 ml·minute−1, p <0.001). This was manifested primarily by increased myocardial blood flow velocity (0.7 – 0.1 to 0.9 – 0.1 second−1, p = 0.01) with unchanged myocardial blood volume (133 – 7 to 137 – 7 a.u., p = ns), the same pattern of coronary microvascular response seen with a low-dose β-adrenergic agonist. Indeed, with hookah, the increased MVO2 was accompanied by decreased heart rate variability, an indirect index of adrenergic overactivity, and eliminated by β-adrenergic blockade (i.v. propranolol). In conclusion, nanoparticle-enriched hookah smoke either is not an acute coronary vasoconstrictor stimulus or its vasoconstrictor effect is too weak to overcome the physiologic dilation of coronary microvessels matching mild cardiac β-adrenergic stimulation. PMID:27067622

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.

Ion transport across the exocrine glands of the frog skin.

PubMed

Mills, J W

1985-01-01

Exposure of the intact frog skin to beta-adrenergic agonists stimulates chloride secretion by the exocrine glands. The secretory response is dependent on Na in the serosal bath and is inhibited by exposure to ouabain and furosemide. Thus the transport mechanism has properties similar to those described for other exocrine glands. Analysis of 3H-ouabain binding sites and determination of intracellular ions by energy dispersive x-ray microanalysis indicates that the transepithelial pathway for Cl flux may be via a distinct group of cells located at the ductal pole of the acinus of two of the gland types; termed mucous and seromucous.

Pharmacogenetics: Implications of Race and Ethnicity on Defining Genetic Profiles for Personalized Medicine

PubMed Central

Ortega, Victor E.; Meyers, Deborah A.

2014-01-01

Pharmacogenetics is being used to develop personalized therapies specific to individuals from different ethnic or racial groups. Pharmacogenetic studies to date have been primarily performed in trial cohorts consisting of non-Hispanic whites of European descent. A “bottleneck” or collapse of genetic diversity associated with the first human colonization of Europe during the Upper Paleolithic period, followed by the recent mixing of African, European, and Native American ancestries has resulted in different ethnic groups with varying degrees of genetic diversity. Differences in genetic ancestry may introduce genetic variation which has the potential to alter the therapeutic efficacy of commonly used asthma therapies, for example β2-adrenergic receptor agonists (beta agonists). Pharmacogenetic studies of admixed ethnic groups have been limited to small candidate gene association studies of which the best example is the gene coding for the receptor target of beta agonist therapy, ADRB2. Large consortium-based sequencing studies are using next-generation whole-genome sequencing to provide a diverse genome map of different admixed populations which can be used for future pharmacogenetic studies. These studies will include candidate gene studies, genome-wide association studies, and whole-genome admixture-based approaches which account for ancestral genetic structure, complex haplotypes, gene-gene interactions, and rare variants to detect and replicate novel pharmacogenetic loci. PMID:24369795

Amphetamine, 3,4-methylenedioxymethamphetamine, lysergic acid diethylamide, and metabolites of the catecholamine neurotransmitters are agonists of a rat trace amine receptor.

PubMed

Bunzow, J R; Sonders, M S; Arttamangkul, S; Harrison, L M; Zhang, G; Quigley, D I; Darland, T; Suchland, K L; Pasumamula, S; Kennedy, J L; Olson, S B; Magenis, R E; Amara, S G; Grandy, D K

2001-12-01

The trace amine para-tyramine is structurally and functionally related to the amphetamines and the biogenic amine neurotransmitters. It is currently thought that the biological activities elicited by trace amines such as p-tyramine and the psychostimulant amphetamines are manifestations of their ability to inhibit the clearance of extracellular transmitter and/or stimulate the efflux of transmitter from intracellular stores. Here we report the discovery and pharmacological characterization of a rat G protein-coupled receptor that stimulates the production of cAMP when exposed to the trace amines p-tyramine, beta-phenethylamine, tryptamine, and octopamine. An extensive pharmacological survey revealed that psychostimulant and hallucinogenic amphetamines, numerous ergoline derivatives, adrenergic ligands, and 3-methylated metabolites of the catecholamine neurotransmitters are also good agonists at the rat trace amine receptor 1 (rTAR1). These results suggest that the trace amines and catecholamine metabolites may serve as the endogenous ligands of a novel intercellular signaling system found widely throughout the vertebrate brain and periphery. Furthermore, the discovery that amphetamines, including 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy"), are potent rTAR1 agonists suggests that the effects of these widely used drugs may be mediated in part by this receptor as well as their previously characterized targets, the neurotransmitter transporter proteins.

Profound and rapid reduction in body temperature induced by the melanocortin receptor agonists.

PubMed

Xu, Yuanzhong; Kim, Eun Ran; Fan, Shengjie; Xia, Yan; Xu, Yong; Huang, Cheng; Tong, Qingchun

2014-08-22

The melanocortin receptor 4 (MC4R) plays a major role in body weight regulation and its agonist MTII has been widely used to study the role of MC4Rs in energy expenditure promotion and feeding reduction. Unexpectedly, we observed that intraperitoneal (i.p.) administration of MTII induced a rapid reduction in both body temperature and energy expenditure, which was independent of its effect on feeding and followed by a prolonged increase in energy expenditure. The rapid reduction was at least partly mediated by brain neurons since intracerebroventricular (icv) administration of alpha melanocyte-stimulating hormone, an endogenous melanocortin receptor agonist, produced a similar response. In addition, the body temperature-lowering effect of MTII was independent of the presence of MC4Rs, but in a similar fashion to the previously shown effect on body temperature by 5'AMP. Moreover, β-adrenergic receptors (β-ARs) were required for the recovery from low body temperature induced by MTII and further pharmacological studies showed that the MTII's effect on body temperature may be partially mediated by the vasopressin V1a receptors. Collectively, our results reveal a previously unappreciated role for the melanocortin pathway in rapidly lowering body temperature. Copyright © 2014 Elsevier Inc. All rights reserved.

Highly sensitive electrochemiluminescent immunosensor based on gold nanoparticles-functionalized zinc oxide nanorod and poly(amidoamine)-graphene for detecting brombuterol.

PubMed

Zhu, Qing; Cai, Fudong; Zhang, Jing; Zhao, Kang; Deng, Anping; Li, Jianguo

2016-12-15

β-adrenergic agonists (β-agonists) recognized as a growth promoter will reflect the health of human. Sensitive detection of β-agonists in foodstuff is valuable for the health of animals and human. A novel ultrasensitive competition-type electrochemiluminescent (ECL) immunosensor was developed for detecting brombuterol (Brom) based on CdTe Quantum dot (QDs) and polyamidoamine dendrimer (PAMAM, G2) modified graphene oxide (GO) (CdTe QDs-PAMAM-GO composite) as bioprobe for the first time. The surface of glassy carbon electrode (GCE) was coated with AuNPs-ZnO NRs composite film as the platform, which facilitated the electronic transmission rate to enhance the ECL intensity and provide enough active sites for capturing antibody. The resulting ECL immunosensor enabled the real samples detection of Brom with a lower detection limit of 0.3pgmL(-1) (S/N=3) and a wider linear range from 0.001 to 500ngmL(-1). The proposed immunosensor coupled with the excellent advantages of CdTe QDs-PAMAM-GO and AuNPs-ZnO NRs composite displayed high sensitivity and long-term stability, and provided an approach for determining other important biomarkers. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Krall, J.F.; Morin, A.

Cells growing in culture with previously described properties of rat uterine smooth muscle accumulated /sup 45/Ca/sup 2 +/ from the medium. Ca/sup 2 +/ uptake by these cells was stimulated by the addition to the medium of 8-bromo-cGMP but not by 8-bromo-cAMP. Ca/sup 2 +/ uptake was also stimulated by carbachol and by the nitro-vasodilator nitroprusside. Although cholinergic agonists have been shown previously to stimulate contraction but not cGMP synthesis in the rat myometrium, both carbachol and nitroprusside stimulated cGMP production by the cultured cells. These results suggested the cells had cholinergic receptor-medicated functions that reflected some neurotransmitter-sensitive properties ofmore » uterine smooth muscle in situ. When determined by a specific radioligand binding assay, subcellular fractions of the cultured cells bound muscarinic cholinergic agonists and antagonists with affinities expected of the muscarinic receptor. The cells were also sensitive to the ..beta..-adrenergic catecholamine agonist isoproterenol, which stimulated cAMP production but not Ca/sup 2 +/ uptake. Carbachol failed to inhibit isoproterenol-dependent cAMP production, which is an important property of the cholinergic receptor in uterine smooth muscle in situ. These results suggest some but not all acetylcholine-sensitive properties of uterine smooth muscle may be retained in cell culture.« less

Molecular interactions of agonist and inverse agonist ligands at serotonin 5-HT2C G protein-coupled receptors: computational ligand docking and molecular dynamics studies validated by experimental mutagenesis results

NASA Astrophysics Data System (ADS)

Córdova-Sintjago, Tania C.; Liu, Yue; Booth, Raymond G.

2015-02-01

To understand molecular determinants for ligand activation of the serotonin 5-HT2C G protein-coupled receptor (GPCR), a drug target for obesity and neuropsychiatric disorders, a 5-HT2C homology model was built according to an adrenergic β2 GPCR (β2AR) structure and validated using a 5-HT2B GPCR crystal structure. The models were equilibrated in a simulated phosphatidyl choline membrane for ligand docking and molecular dynamics studies. Ligands included (2S, 4R)-(-)-trans-4-(3'-bromo- and trifluoro-phenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalene-2-amine (3'-Br-PAT and 3'-CF3-PAT), a 5-HT2C agonist and inverse agonist, respectively. Distinct interactions of 3'-Br-PAT and 3'-CF3-PAT at the wild-type (WT) 5-HT2C receptor model were observed and experimental 5-HT2C receptor mutagenesis studies were undertaken to validate the modelling results. For example, the inverse agonist 3'-CF3-PAT docked deeper in the WT 5-HT2C binding pocket and altered the orientation of transmembrane helices (TM) 6 in comparison to the agonist 3'-Br-PAT, suggesting that changes in TM orientation that result from ligand binding impact function. For both PATs, mutation of 5-HT2C residues S3.36, T3.37, and F5.47 to alanine resulted in significantly decreased affinity, as predicted from modelling results. It was concluded that upon PAT binding, 5-HT2C residues T3.37 and F5.47 in TMs 3 and 5, respectively, engage in inter-helical interactions with TMs 4 and 6, respectively. The movement of TMs 5 and 6 upon agonist and inverse agonist ligand binding observed in the 5-HT2C receptor modelling studies was similar to movements reported for the activation and deactivation of the β2AR, suggesting common mechanisms among aminergic neurotransmitter GPCRs.

Airway Peroxidases Catalyze Nitration of the β2-Agonist Salbutamol and Decrease Its Pharmacological Activity

PubMed Central

Sallans, Larry; Macha, Stephen; Brown, Kari; McGraw, Dennis W.; Kovacic, Melinda Butsch; Britigan, Bradley E.

2011-01-01

β2-Agonists are the most effective bronchodilators for the rapid relief of asthma symptoms, but for unclear reasons, their effectiveness may be decreased during severe exacerbations. Because peroxidase activity and nitrogen oxides are increased in the asthmatic airway, we examined whether salbutamol, a clinically important β2-agonist, is subject to potentially inactivating nitration. When salbutamol was exposed to myeloperoxidase, eosinophil peroxidase or lactoperoxidase in the presence of hydrogen peroxide (H2O2) and nitrite (NO2−), both absorption spectroscopy and mass spectrometry indicated formation of a new metabolite with features expected for the nitrated drug. The new metabolites showed an absorption maximum at 410 nm and pKa of 6.6 of the phenolic hydroxyl group. In addition to nitrosalbutamol (m/z 285.14), a salbutamol-derived nitrophenol, formed by elimination of the formaldehyde group, was detected (m/z 255.13) by mass spectrometry. It is noteworthy that the latter metabolite was detected in exhaled breath condensates of asthma patients receiving salbutamol but not in unexposed control subjects, indicating the potential for β2-agonist nitration to occur in the inflamed airway in vivo. Salbutamol nitration was inhibited in vitro by ascorbate, thiocyanate, and the pharmacological agents methimazole and dapsone. The efficacy of inhibition depended on the nitrating system, with the lactoperoxidase/H2O2/NO2− being the most affected. Functionally, nitrated salbutamol showed decreased affinity for β2-adrenergic receptors and impaired cAMP synthesis in airway smooth muscle cells compared with the native drug. These results suggest that under inflammatory conditions associated with asthma, phenolic β2-agonists may be subject to peroxidase-catalyzed nitration that could potentially diminish their therapeutic efficacy. PMID:20974700

alpha2-Adrenergic agonists antagonise the anxiolytic-like effect of antidepressants in the four-plate test in mice.

PubMed

Massé, Fabienne; Hascoët, Martine; Bourin, Michel

2005-10-14

Selective serotonin reuptake inhibitors (SSRIs) and serotonin/noradrenaline reuptake inhibitors (SNRIs) has been reported to be efficient in anxiety disorders. Some animal models have demonstrated an anxiolytic-like effect following acute administration, however, it is not yet known how noradrenergic receptors are implicated in the therapeutic effects of antidepressants (ADs) in anxiety. The effects of two alpha(2)-adrenoceptor agonists (clonidine, guanabenz) on anxiolytic-like effect of two SSRIs (paroxetine and citalopram) and two SNRIs (venlafaxine and milnacipran) were evaluated in the four-plate test (FPT) in mice. Paroxetine (4 mg/kg), citalopram (8 mg/kg), venlafaxine (8 mg/kg), and milnacipran (8 mg/kg) administered intraperitoneally (i.p.) increased the number of punishments accepted by mice in the FPT. Clonidine (0.0039-0.5 mg/kg) and guanabenz (0.03-0.5mg/kg) had no effect on the number of punishments accepted by mice. Clonidine (0.03 and 0.06 mg/kg) and guanabenz (0.125 and 0.5 mg/kg) (i.p. -45 min) reversed the anti-punishment effect of paroxetine, citalopram, venlafaxine and milnacipran (i.p. -30 min). But if the antidepressants are administered 45 min before the test and alpha(2)-adrenoceptor agonists 30 min before the test, alpha(2)-adrenoceptor agonists failed to alter the anti-punishment effect of antidepressants. The results of this present study indicate that alpha(2)-adrenoceptor agonists antagonise the anxiolytic-like effect of antidepressants in mice when they are administered 15 min before the administration of antidepressant suggesting a close inter-regulation between noradrenergic and serotoninergic system in the mechanism of SSRIs and SNRIs in anxiety-like behaviour.

Identification of Novel Transplantable GPCR Recycling Motif for Drug Discovery

PubMed Central

Nooh, Mohammed M.; Mancarella, Salvatore; Bahouth, Suleiman W.

2016-01-01

β1-adrenergic receptor (β1-AR) agonists and antagonists are widely used in the treatment of major cardiovascular diseases such as heart failure and hypertension. The β1-AR like other G protein-couple receptors (GPCR) is endocytosed in response to intense agonist activation. Recycling of the agonist-internalized β1-AR is dependent on its carboxy-terminal type-1 PSD-95/DLG/ZO1 (PDZ) and on phospho-serine312 in the third intracellular loop of the β1-AR. Progressive elongation of the β1-AR at its C-tail inactivated the PDZ-biding domain and inhibited the recycling of the β1-AR. However, fusing a twenty amino acid peptide derived from the multiple cloning region of the mammalian expression vector pCDNA3 to the C-tail of the β1-AR (β1-AR[+20]) produced a chimeric β1-AR that recycled rapidly and efficiently. The β1-AR[+20] recycled in a type-1 PDZ and phospho-Ser312-independent manner, indicating that this peptide provided a general GPCR recycling signal. Fusing the enhanced yellow fluorescent protein (EYFP) down-stream of β1-AR[+20] generated a β1-AR-EYFP chimera that was expressed on the membrane and recycled efficiently after agonist-induced internalization. This construct trafficked in a PDZ-SNX27/retromer-independent manner. We also fused EYFP to the N-terminus of the β1-AR to created EYFP-WT β1-AR. This construct recycled in PDZ and SNX27/retromer dependent manner. These β1-AR-EYFP constructs would be useful for high throughput screening (HTS) programs to identify new entities that would interfere with the recycling of agonist internalized GPCR that traffic in PDZ-dependent vs. PDZ-independent roadmaps. PMID:27645110

Constitutive glycogen synthase kinase-3α/β activity protects against chronic β-adrenergic remodelling of the heart

PubMed Central

Webb, Ian G.; Nishino, Yasuhiro; Clark, James E.; Murdoch, Colin; Walker, Simon J.; Makowski, Marcus R.; Botnar, Rene M.; Redwood, Simon R.; Shah, Ajay M.; Marber, Michael S.

2010-01-01

Aims Glycogen synthase kinase 3 (GSK-3) signalling is implicated in the growth of the heart during development and in response to stress. However, its precise role remains unclear. We set out to characterize developmental growth and response to chronic isoproterenol (ISO) stress in knockin (KI) mice lacking the critical N-terminal serines, 21 of GSK-3α and 9 of GSK-3β respectively, required for inactivation by upstream kinases. Methods and results Between 5 and 15 weeks, KI mice grew more rapidly, but normalized heart weight and contractile performance were similar to wild-type (WT) mice. Isolated hearts of both genotypes responded comparably to acute ISO infusion with increases in heart rate and contractility. In WT mice, chronic subcutaneous ISO infusion over 14 days resulted in cardiac hypertrophy, interstitial fibrosis, and impaired contractility, accompanied by foetal gene reactivation. These effects were all significantly attenuated in KI mice. Indeed, ISO-treated KI hearts demonstrated reversible physiological remodelling traits with increased stroke volume and a preserved contractile response to acute adrenergic stimulation. Furthermore, simultaneous pharmacological inhibition of GSK-3 in KI mice treated with chronic subcutaneous ISO recapitulated the adverse remodelling phenotype seen in WT hearts. Conclusion Expression of inactivation-resistant GSK-3α/β does not affect eutrophic myocardial growth but protects against pathological hypertrophy induced by chronic adrenergic stimulation, maintaining cardiac function and attenuating interstitial fibrosis. Accordingly, strategies to prevent phosphorylation of Ser-21/9, and consequent inactivation of GSK-3α/β, may enable a sustained cardiac response to chronic β-agonist stimulation while preventing pathological remodelling. PMID:20299330

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.

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

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.

Molecular Basis of Ligand Dissociation in β-Adrenergic Receptors

PubMed Central

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

2011-01-01

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

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.

The effects of spaceflight on adrenergic receptors and agonists and cell adhesion molecule expression

NASA Technical Reports Server (NTRS)

Mills, Paul J.; Perez, Christy J.; Adler, Karen A.; Ziegler, Michael G.; Meck, J. V. (Principal Investigator)

2002-01-01

Twenty-two astronauts who flew aboard 10 different US Space Shuttle flights were studied 10 days before launch, on landing day, and 2-4 days post-landing. After landing, plasma levels of norepinephrine (p<0.01) were elevated. Lymphocyte beta(2)-adrenergic receptors were desensitized 2-4 days post-landing (p<0.02). The density of CD62L on lymphocytes was unchanged but the densities of CD11a (p<0.01) and CD54 (p<0.001) were down-regulated. CD11a density was also down-regulated on monocytes (p<0.01). Neutrophils showed an up-regulation of CD11a (p<0.01) and a down-regulation of CD54 (p<0.01). CD11a density on neutrophils remained up-regulated (p<0.01) and CD54 density remained down-regulated (p<0.01) at 2-4 days post-landing. Circulating levels of soluble ICAM-1 (CD54) and soluble E-selectin (CD62E) were decreased after landing (p's<0.05). The data suggest that spaceflight leads to an environment that would support reduced leukocyte-endothelial adhesion. Sympathetic activation may contribute to this phenomenon.

Dissociation Between Brown Adipose Tissue 18F-FDG Uptake and Thermogenesis in Uncoupling Protein 1-Deficient Mice.

PubMed

Hankir, Mohammed K; Kranz, Mathias; Keipert, Susanne; Weiner, Juliane; Andreasen, Sille G; Kern, Matthias; Patt, Marianne; Klöting, Nora; Heiker, John T; Brust, Peter; Hesse, Swen; Jastroch, Martin; Fenske, Wiebke K

2017-07-01

18 F-FDG PET imaging is routinely used to investigate brown adipose tissue (BAT) thermogenesis, which requires mitochondrial uncoupling protein 1 (UCP1). It remains uncertain, however, whether BAT 18 F-FDG uptake is a reliable surrogate measure of UCP1-mediated heat production. Methods: UCP1 knockout (KO) and wild-type (WT) mice housed at thermoneutrality were treated with the selective β3 adrenergic receptor agonist CL 316, 243 and underwent metabolic cage, infrared thermal imaging and 18 F-FDG PET/MRI experiments. Primary brown adipocytes were additionally examined for their bioenergetics by extracellular flux analysis as well as their uptake of 2-deoxy- 3 H-glucose. Results: In response to CL 316, 243 treatments, oxygen consumption, and BAT thermogenesis were diminished in UCP1 KO mice, but BAT 18 F-FDG uptake was fully retained. Isolated UCP1 KO brown adipocytes exhibited defective induction of uncoupled respiration whereas their glycolytic flux and 2-deoxy- 3 H-glucose uptake rates were largely unaffected. Conclusion: Adrenergic stimulation can increase BAT 18 F-FDG uptake independently of UCP1 thermogenic function. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

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

Chromosome mapping of the human arrestin (SAG), {beta}-arrestin 2 (ARRB2), and {beta}-adrenergic receptor kinase 2 (ADRBK2) genes

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

Calabrese, G.; Sallese, M.; Stornaiuolo, A.

1994-09-01

Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {beta}-adrenergic receptor kinase ({beta}ARK), which phosphorylates the agonist-occupied receptor and its functional cofactor, {beta}-arrestin. Both {beta}ARK and {beta}-arrestin are members of multigene families. The family of G-protein-coupled receptor kinases includes rhodopsin kinase, {beta}ARK1, {beta}ARK2, IT11-A (GRK4), GRK5, and GRK6. The arrestin/{beta}-arrestin gene family includes arrestin (also known as S-antigen), {beta}-arrestin 1, and {beta}-arrestin 2. Here we report the chromosome mapping of the human genes for arrestin (SAG), {beta}arrestin 2 (ARRB2), and {beta}ARK2 (ADRBK2) by fluorescence in situ hybridization (FISH). FISH results confirmed the assignment ofmore » the gene coding for arrestin (SAG) to chromosome 2 and allowed us to refine its localization to band q37. The gene coding for {beta}-arrestin 2 (ARRB2) was mapped to chromosome 17p13 and that coding for {beta}ARK2 (ADRBK2) to chromosome 22q11. 17 refs., 1 fig.« less

Rapid analysis of clenbuterol, salbutamol, procaterol, and fenoterol in pharmaceuticals and human urine by capillary electrophoresis.

PubMed

Sirichai, Somsak; Khanatharana, Proespichaya

2008-09-15

Capillary electrophoresis (CE) with UV detection for the simultaneous and short-time analysis of clenbuterol, salbutamol, procaterol, fenoterol is described and validated. Optimized conditions were found to be a 10 mmoll(-1) borate buffer (pH 10.0), an separation voltage of 19 kV, and a separation temperature of 32 degrees C. Detection was set at 205 nm. Under the optimized conditions, analyses of the four analytes in pharmaceutical and human urine samples were carried out in approximately 1 min. The interference of the sample matrix was not observed. The LOD (limits of detection) defined at S/N of 3:1 was found between 0.5 and 2.0 mgl(-1) for the analytes. The linearity of the detector response was within the range from 2.0 to 30 mgl(-1) with correlation coefficient >0.996.

ASM-024, a Piperazinium Compound, Promotes the In Vitro Relaxation of β2-Adrenoreceptor Desensitized Tracheas

PubMed Central

Israël-Assayag, Evelyne; Beaulieu, Marie-Josée; Cormier, Yvon

2015-01-01

Inhaled β2-adrenoreceptor agonists are widely used in asthma and chronic obstructive pulmonary disease (COPD) for bronchoconstriction relief. β2-adrenoreceptor agonists relax airway smooth muscle cells via cyclic adenosine monophosphate (cAMP) mediated pathways. However, prolonged stimulation induces functional desensitization of the β2-adrenoreceptors (β2-AR), potentially leading to reduced clinical efficacy with chronic or prolonged administration. ASM-024, a small synthetic molecule in clinical stage development, has shown activity at the level of nicotinic receptors and possibly at the muscarinic level and presents anti-inflammatory and bronchodilator properties. Aerosolized ASM-024 reduces airway resistance in mice and promotes in-vitro relaxation of tracheal and bronchial preparations from animal and human tissues. ASM-024 increased in vitro relaxation response to maximally effective concentration of short—acting beta-2 agonists in dog and human bronchi. Although the precise mechanisms by which ASM-024 promotes airway smooth muscle (ASM) relaxation remain unclear, we hypothesized that ASM-024 will attenuate and/or abrogate agonist-induced contraction and remain effective despite β2-AR tachyphylaxis. β2-AR tachyphylaxis was induced with salbutamol, salmeterol and formoterol on guinea pig tracheas. The addition of ASM-024 relaxed concentration-dependently intact or β2-AR desensitized tracheal rings precontracted with methacholine. ASM-024 did not induce any elevation of intracellular cAMP in isolated smooth muscle cells; moreover, blockade of the cAMP pathway with an adenylate cyclase inhibitor had no significant effect on ASM-024-induced guinea pig trachea relaxation. Collectively, these findings show that ASM-024 elicits relaxation of β2-AR desensitized tracheal preparations and suggest that ASM-024 mediates smooth muscle relaxation through a different target and signaling pathway than β2-adrenergic receptor agonists. These findings suggest ASM-024 could potentially provide clinical benefit when used adjunctively with inhaled β2-adrenoreceptor agonists in those patients exhibiting a reduced response to their chronic use. PMID:25799096

ASM-024, a piperazinium compound, promotes the in vitro relaxation of β2-adrenoreceptor desensitized tracheas.

PubMed

Israël-Assayag, Evelyne; Beaulieu, Marie-Josée; Cormier, Yvon

2015-01-01

Inhaled β2-adrenoreceptor agonists are widely used in asthma and chronic obstructive pulmonary disease (COPD) for bronchoconstriction relief. β2-Adrenoreceptor agonists relax airway smooth muscle cells via cyclic adenosine monophosphate (cAMP) mediated pathways. However, prolonged stimulation induces functional desensitization of the β2-adrenoreceptors (β2-AR), potentially leading to reduced clinical efficacy with chronic or prolonged administration. ASM-024, a small synthetic molecule in clinical stage development, has shown activity at the level of nicotinic receptors and possibly at the muscarinic level and presents anti-inflammatory and bronchodilator properties. Aerosolized ASM-024 reduces airway resistance in mice and promotes in-vitro relaxation of tracheal and bronchial preparations from animal and human tissues. ASM-024 increased in vitro relaxation response to maximally effective concentration of short-acting beta-2 agonists in dog and human bronchi. Although the precise mechanisms by which ASM-024 promotes airway smooth muscle (ASM) relaxation remain unclear, we hypothesized that ASM-024 will attenuate and/or abrogate agonist-induced contraction and remain effective despite β2-AR tachyphylaxis. β2-AR tachyphylaxis was induced with salbutamol, salmeterol and formoterol on guinea pig tracheas. The addition of ASM-024 relaxed concentration-dependently intact or β2-AR desensitized tracheal rings precontracted with methacholine. ASM-024 did not induce any elevation of intracellular cAMP in isolated smooth muscle cells; moreover, blockade of the cAMP pathway with an adenylate cyclase inhibitor had no significant effect on ASM-024-induced guinea pig trachea relaxation. Collectively, these findings show that ASM-024 elicits relaxation of β2-AR desensitized tracheal preparations and suggest that ASM-024 mediates smooth muscle relaxation through a different target and signaling pathway than β2-adrenergic receptor agonists. These findings suggest ASM-024 could potentially provide clinical benefit when used adjunctively with inhaled β2-adrenoreceptor agonists in those patients exhibiting a reduced response to their chronic use.

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.

Fenoterol did not enhance glucocorticoid-induced skeletal changes in male rats.

PubMed

Folwarczna, Joanna; Nowińska, Barbara; Śliwiński, Leszek; Pytlik, Maria; Cegieła, Urszula; Betka, Anna

2011-01-01

Glucocorticoids and β(2)-adrenergic receptor agonists are the most commonly used drugs in the treatment of asthma. Both therapies are potentially dangerous to the skeletal system. The aim of the present study was to investigate the effects of fenoterol, a β(2)-receptor agonist, on the development of bone changes induced by glucocorticoid (prednisolone) administration in mature male rats. The experiments were carried out on 24-week-old male Wistar rats. The effects of prednisolone 21-hemisuccinate sodium salt (7 mg/kg s.c. daily) or/and fenoterol hydrobromide (1.4 mg/kg i.p. daily), administered for 4 weeks, on the skeletal system were studied. Bone turnover markers, geometric parameters, mass, mass of bone mineral in the tibia, femur and L-4 vertebra, bone histomorphometric parameters and mechanical properties of tibial metaphysis, femoral diaphysis and femoral neck were determined. Both prednisolone and fenoterol had damaging effects on the skeletal system of mature male rats. However, concurrent administration of fenoterol and prednisolone did not result in the intensification of the deleterious skeletal effect of either drug administered separately.

Dual agonist occupancy of AT1-R–α2C-AR heterodimers results in atypical Gs-PKA signaling

PubMed Central

Bellot, Morgane; Galandrin, Ségolène; Boularan, Cédric; Matthies, Heinrich J; Despas, Fabien; Denis, Colette; Javitch, Jonathan; Mazères, Serge; Sanni, Samra Joke; Pons, Véronique; Seguelas, Marie-Hélène; Hansen, Jakob L; Pathak, Atul; Galli, Aurelio; Sénard, Jean-Michel; Galés, Céline

2015-01-01

Hypersecretion of norepinephrine (NE) and angiotensin II (AngII) is a hallmark of major prevalent cardiovascular diseases that contribute to cardiac pathophysiology and morbidity. Herein, we explore whether heterodimerization of presynaptic AngII AT1 receptor (AT1-R) and NE α2C-adrenergic receptor (α2C-AR) could underlie their functional cross-talk to control NE secretion. Multiple bioluminescence resonance energy transfer and protein complementation assays allowed us to accurately probe the structures and functions of the α2C-AR–AT1-R dimer promoted by ligand binding to individual protomers. We found that dual agonist occupancy resulted in a conformation of the heterodimer different from that induced by active individual protomers and triggered atypical Gs-cAMP–PKA signaling. This specific pharmacological signaling unit was identified in vivo to promote not only NE hypersecretion in sympathetic neurons but also sympathetic hyperactivity in mice. Thus, we uncovered a new process by which GPCR heterodimerization creates an original functional pharmacological entity and that could constitute a promising new target in cardiovascular therapeutics. PMID:25706338

Modification of certain pharmacological effects of ethanol by lipophilic alpha-1 adrenergic agonists

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

Menon, M.K.; Dinovo, E.C.; Haddox, V.G.

The influence of four centrally-acting alpha-1 adrenoceptor agonists, namely, 2(2-chloro-5-trifluoromethylphenylimino) imidazolidine (St 587), cirazoline, (-) 1,2,3,4-tetrahydro-8-methoxy-5-methylthio-2-naphthalenamine ((-)SKF 89748A) and 2-(2-methylindazol-4-imino)imidazolidine (Sgd 101/75) on the pharmacological effects of ethanol was investigated. All four drugs reduced the duration of ethanol-induced hypnosis in C57B1/6 mice, this effect being proportional to their relative potencies to exert central alpha-1 agonism. In prazosin-pretreated mice, St 587 failed to reduce the hypnotic effect of ethanol, which provided strong evidence for the role of alpha-1 agonism for the hypnosis reducing effect of St 587. Hyperactivity induced in C57B1/6 mice by a subhypnotic dose of ethanol and St 587more » was reported earlier. In the present study, St 587, cirazoline and (-)SKF 89748A produced similar response, but no correlation between this effect and ethanol hypnosis blockade could be established. 19 references, 8 figures, 2 tables.« less

Preliminary UK experience of dexmedetomidine, a novel agent for postoperative sedation in the intensive care unit.

PubMed

Venn, R M; Bradshaw, C J; Spencer, R; Brealey, D; Caudwell, E; Naughton, C; Vedio, A; Singer, M; Feneck, R; Treacher, D; Willatts, S M; Grounds, R M

1999-12-01

Dexmedetomidine, a highly selective and potent alpha2-adrenergic agonist, has a potentially useful role as a sedative agent in patients requiring intensive care. As part of a larger European multicentre trial, a total of 119 postoperative cardiac and general surgical patients requiring ventilation and sedation in an intensive care unit were enrolled in four centres in the United Kingdom. One hundred and five patients were randomly allocated to receive either dexmedetomidine or placebo with rescue sedation and analgesia provided by midazolam and morphine, respectively. Compared with the control group, intubated patients receiving dexmedetomidine required 80% less midazolam [mean 4.9 (5.8) microg.kg-1.h-1 vs. 23.7 (27.5) microg.kg-1.h-1, p < 0.0001], and 50% less morphine [11.2 (13.4) microg.kg-1.h-1 vs. 21.5 (19.4) microg.kg-1.h-1,p = 0.0006]. Cardiovascular effects and adverse events could be predicted from the known properties of alpha-2 agonists. In conclusion, dexmedetomidine is a useful agent for the provision of postoperative analgesia and sedation.

Effects of immunocastration and β-adrenergic agonists on the performance and carcass traits of feedlot finished Nellore cattle.

PubMed

Antonelo, D S; Mazon, M R; Nubiato, K E Z; Gómez, J F M; Brigida, D J; Gomes, R C; Netto, A S; Leme, P R; Silva, S L

2017-11-01

β-Adrenergic agonists (β-AA) are non-hormonal growth promoters which promote muscle hypertrophy in supplemented animals. The effects of two β-AA in combination with the immunocastration technique on the performance and carcass traits were evaluated using 96 feedlot Nellore males in a randomized complete block design with two sex conditions (immunocastrated (IC) v. non-castrated (NC)) and three treatments: CON (no β-agonists added), RH (300 mg of ractopamine hydrochloride/day, for 33 days) or ZH (80 mg of zilpaterol·hydrochloride animal/day for 30 days, removed 3 days for required withdrawal period). The trial was carried for 100 days where in the first 70 days animals did not receive β-AA (phase 1) and during the last 30 days they were treated with β-AA (phase 2). The performance and ultrasound measurements of longissimus muscle area (LMA), backfat thickness (BFT) and rump fat thickness (RFT) were evaluated in both phases. No sex condition v. treatment interactions were observed for any trait. The NC animals had higher average daily gain (ADG) and final BW than the IC animals, but they did not differ in dry matter intake (DMI) and feed efficiency (gain to feed). The NC animals showed greater LMA (P=0.0001) and hot carcass weight (P=0.0006), and smaller BFT (P=0.0007), RFT (P=0.0039) and percentage of kidney, pelvic and heart fat (P<0.0001) when compared with IC animals. The animals fed ZH showed greater ADG (P=0.0002), G : F (P<0.0001) and dressing per cent (P=0.0136) than those fed RH and CON diets. No differences in BW and DMI were observed. A interaction between treatment and time on feed was observed for LMA and BFT, in which the animals fed ZH diet showed greater LMA (P<0.01) and lower BFT (P<0.01) at 100 days than the animals fed RH and CON diets, whereas RH and CON diets did not differ. Immunocastration decreases muscle development and increases carcass finishing. In contrast, β-AA increases muscle and decreases fat deposition. The ZH has a higher action on the muscle metabolism than animals fed RH diet. However, RH diet achieves a better balance because it has an intermediary performance between non-supplemented and ZH animals and does not decrease the carcass fat.

Differential regulation of the slow and rapid components of guinea-pig cardiac delayed rectifier K+ channels by hypoxia

PubMed Central

Hool, Livia C

2004-01-01

The aim of this study was to examine the effects of acute hypoxia on the slow (IKs) and rapid (IKr) components of the native delayed rectifier K+ channel in the absence and presence of the β-adrenergic receptor agonist isoproterenol (isoprenaline; Iso) using the whole-cell configuration of the patch-clamp technique. Hypoxia reversibly inhibited basal IKs. The effect could be mimicked by exposing the cells to the thiol-specific reducing agent dithiothreitol (DTT) and attenuated upon exposure of cells to the membrane-impermeant thiol-specific oxidizing compound 5,5′-dithio-bis[2-nitrobenzoic acid] (DTNB). In the presence of hypoxia, the K0.5 for activation of IKs by Iso was significantly decreased from 18.3 to 1.9 nm. DTT mimicked the effect of hypoxia on the sensitivity of IKs to Iso while DTNB had no effect. Hypoxia increased the sensitivity of IKs to histamine and forskolin suggesting that the effect of hypoxia is not occurring at the β-adrenergic receptor. The increase in sensitivity of IKs to Iso could be attenuated with addition of PKCβ peptide to the pipette solution. While hypoxia and DTT inhibited basal IKs they were without effect on IKr. In addition, Iso did not appear to alter the magnitude of IKr in the absence or presence of hypoxia. These data suggest that hypoxia regulates native IKs through two distinct mechanisms: direct inhibition of basal IKs and an increase in sensitivity to Iso that occurs downstream from the β-adrenergic receptor. Both mechanisms appear to involve redox modification of thiol groups. In contrast native IKr does not appear to be regulated by Iso, hypoxia or redox state. PMID:14634203

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.

β-Adrenergic induction of lipolysis in hepatocytes is inhibited by ethanol exposure.

PubMed

Schott, Micah B; Rasineni, Karuna; Weller, Shaun G; Schulze, Ryan J; Sletten, Arthur C; Casey, Carol A; McNiven, Mark A

2017-07-14

In liver steatosis ( i.e. fatty liver), hepatocytes accumulate many large neutral lipid storage organelles known as lipid droplets (LDs). LDs are important in the maintenance of energy homeostasis, but the signaling mechanisms that stimulate LD metabolism in hepatocytes are poorly defined. In adipocytes, catecholamines target the β-adrenergic (β-AR)/cAMP pathway to activate cytosolic lipases and induce their recruitment to the LD surface. Therefore, the goal of this study was to determine whether hepatocytes, like adipocytes, also undergo cAMP-mediated lipolysis in response to β-AR stimulation. Using primary rat hepatocytes and human hepatoma cells, we found that treatment with the β-AR agent isoproterenol caused substantial LD loss via activation of cytosolic lipases adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). β-Adrenergic stimulation rapidly activated PKA, which led to the phosphorylation of ATGL and HSL and their recruitment to the LD surface. To test whether this β-AR-dependent lipolysis pathway was altered in a model of alcoholic fatty liver, primary hepatocytes from rats fed a 6-week EtOH-containing Lieber-DeCarli diet were treated with cAMP agonists. Compared with controls, EtOH-exposed hepatocytes showed a drastic inhibition in β-AR/cAMP-induced LD breakdown and the phosphorylation of PKA substrates, including HSL. This observation was supported in VA-13 cells, an EtOH-metabolizing human hepatoma cell line, which displayed marked defects in both PKA activation and isoproterenol-induced ATGL translocation to the LD periphery. In summary, these findings suggest that β-AR stimulation mobilizes cytosolic lipases for LD breakdown in hepatocytes, and perturbation of this pathway could be a major consequence of chronic EtOH insult leading to fatty liver.

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.

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.

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.

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.