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Sample records for weak agonist activity

  1. ?-galactosylceramide analogs with weak agonist activity for human iNKT cells define new candidate anti-inflammatory agents.

    PubMed

    Bricard, Gabriel; Venkataswamy, Manjunatha M; Yu, Karl O A; Im, Jin S; Ndonye, Rachel M; Howell, Amy R; Veerapen, Natacha; Illarionov, Petr A; Besra, Gurdyal S; Li, Qian; Chang, Young-Tae; Porcelli, Steven A

    2010-01-01

    CD1d-restricted natural killer T cells with invariant T cell receptor ? chains (iNKT cells) are a unique lymphocyte subset that responds to recognition of specific lipid and glycolipid antigens. They are conserved between mice and humans and exert various immunoregulatory functions through their rapid secretion of a variety of cytokines and secondary activation of dendritic cells, B cells and NK cells. In the current study, we analyzed the range of functional activation states of human iNKT cells using a library of novel analogs of ?-galactosylceramide (?GalCer), the prototypical iNKT cell antigen. Measurement of cytokines secreted by human iNKT cell clones over a wide range of glycolipid concentrations revealed that iNKT cell ligands could be classified into functional groups, correlating with weak versus strong agonistic activity. The findings established a hierarchy for induction of different cytokines, with thresholds for secretion being consistently lowest for IL-13, higher for interferon-? (IFN?), and even higher for IL-4. These findings suggested that human iNKT cells can be intrinsically polarized to selective production of IL-13 by maintaining a low level of activation using weak agonists, whereas selective polarization to IL-4 production cannot be achieved through modulating the strength of the activating ligand. In addition, using a newly designed in vitro system to assess the ability of human iNKT cells to transactivate NK cells, we found that robust secondary induction of interferon-? secretion by NK cells was associated with strong but not weak agonist ligands of iNKT cells. These results indicate that polarization of human iNKT cell responses to Th2-like or anti-inflammatory effects may best be achieved through selective induction of IL-13 and suggest potential discrepancies with findings from mouse models that may be important in designing iNKT cell-based therapies in humans. PMID:21179412

  2. ?-Galactosylceramide Analogs with Weak Agonist Activity for Human iNKT Cells Define New Candidate Anti-Inflammatory Agents

    PubMed Central

    Bricard, Gabriel; Venkataswamy, Manjunatha M.; Yu, Karl O. A.; Im, Jin S.; Ndonye, Rachel M.; Howell, Amy R.; Veerapen, Natacha; Illarionov, Petr A.; Besra, Gurdyal S.; Li, Qian; Chang, Young-Tae; Porcelli, Steven A.

    2010-01-01

    CD1d-restricted natural killer T cells with invariant T cell receptor ? chains (iNKT cells) are a unique lymphocyte subset that responds to recognition of specific lipid and glycolipid antigens. They are conserved between mice and humans and exert various immunoregulatory functions through their rapid secretion of a variety of cytokines and secondary activation of dendritic cells, B cells and NK cells. In the current study, we analyzed the range of functional activation states of human iNKT cells using a library of novel analogs of ?-galactosylceramide (?GalCer), the prototypical iNKT cell antigen. Measurement of cytokines secreted by human iNKT cell clones over a wide range of glycolipid concentrations revealed that iNKT cell ligands could be classified into functional groups, correlating with weak versus strong agonistic activity. The findings established a hierarchy for induction of different cytokines, with thresholds for secretion being consistently lowest for IL-13, higher for interferon-? (IFN?), and even higher for IL-4. These findings suggested that human iNKT cells can be intrinsically polarized to selective production of IL-13 by maintaining a low level of activation using weak agonists, whereas selective polarization to IL-4 production cannot be achieved through modulating the strength of the activating ligand. In addition, using a newly designed in vitro system to assess the ability of human iNKT cells to transactivate NK cells, we found that robust secondary induction of interferon-? secretion by NK cells was associated with strong but not weak agonist ligands of iNKT cells. These results indicate that polarization of human iNKT cell responses to Th2-like or anti-inflammatory effects may best be achieved through selective induction of IL-13 and suggest potential discrepancies with findings from mouse models that may be important in designing iNKT cell-based therapies in humans. PMID:21179412

  3. Weak rappers rock more: hermit crabs assess their own agonistic behaviour.

    PubMed

    Edmonds, Elizabeth; Briffa, Mark

    2016-01-01

    Fighting animals use a variety of information sources to make strategic decisions. A neglected potential source of information is an individual's own performance during a fight. Surprisingly, this possibility has yet to be incorporated into the large body of theory concerning the evolution of aggressive behaviour. Here, by experimentally dampening the impact of their shell rapping behaviour, we test for the possibility that attacking hermit crabs monitor their own fight performance. Attackers with dampened raps did not show a reduction in the number of raps used. By contrast, they showed an increased frequency of a less intense agonistic behaviour, shell rocking. This change in behaviour, in attackers that are forced to rap weakly, indicates that they assess their own agonistic behaviour. PMID:26740563

  4. μ-opioid receptors: correlation of agonist efficacy for signalling with ability to activate internalization.

    PubMed

    McPherson, Jamie; Rivero, Guadalupe; Baptist, Myma; Llorente, Javier; Al-Sabah, Suleiman; Krasel, Cornelius; Dewey, William L; Bailey, Chris P; Rosethorne, Elizabeth M; Charlton, Steven J; Henderson, Graeme; Kelly, Eamonn

    2010-10-01

    We have compared the ability of a number of μ-opioid receptor (MOPr) ligands to activate G proteins with their abilities to induce MOPr phosphorylation, to promote association of arrestin-3 and to cause MOPr internalization. For a model of G protein-coupled receptor (GPCR) activation where all agonists stabilize a single active conformation of the receptor, a close correlation between signaling outputs might be expected. Our results show that overall there is a very good correlation between efficacy for G protein activation and arrestin-3 recruitment, whereas a few agonists, in particular endomorphins 1 and 2, display apparent bias toward arrestin recruitment. The agonist-induced phosphorylation of MOPr at Ser(375), considered a key step in MOPr regulation, and agonist-induced internalization of MOPr were each found to correlate well with arrestin-3 recruitment. These data indicate that for the majority of MOPr agonists the ability to induce receptor phosphorylation, arrestin-3 recruitment, and internalization can be predicted from their ability as agonists to activate G proteins. For the prototypic MOPr agonist morphine, its relatively weak ability to induce MOPr internalization can be explained by its low agonist efficacy. PMID:20647394

  5. Efficient help for autoreactive B cell activation requires CD4+ T cell recognition of an agonist peptide at the effector stage

    PubMed Central

    Hondowicz, Brian D.; Batheja, Amrita O.; Metzgar, Michele H.; Pagán, Antonio J.; Perng, Olivia A.; Willms, Simone; Caton, Andrew J.; Erikson, Jan

    2010-01-01

    T cell recognition of peptide/MHC complexes is flexible and can lead to differential activation, but how interactions with agonist (full activation) or partial agonist (suboptimal activation) peptides can shape immune responses in vivo is not well characterized. We investigated the effect of stimulation by agonist or partial agonist ligands during initial CD4+ T cell priming, and subsequent T-B cell cognate interactions, on antibody production by anti-chromatin B cells. We found that autoantibody production required TCR recognition of an agonist peptide at the effector stage of B cell activation. However, interaction with a weak agonist ligand at this effector stage failed to promote efficient autoantibody production, even if the CD4+ T cells were fully primed by an agonist peptide. These studies suggest that the reactivity of the TCR for a target self-peptide during CD4+ T-B cell interaction can be a critical determinant in restraining anti-chromatin autoantibody production. PMID:19662636

  6. μ-Opioid Receptors: Correlation of Agonist Efficacy for Signalling with Ability to Activate InternalizationS⃞

    PubMed Central

    McPherson, Jamie; Rivero, Guadalupe; Baptist, Myma; Llorente, Javier; Al-Sabah, Suleiman; Krasel, Cornelius; Dewey, William L.; Bailey, Chris P.; Rosethorne, Elizabeth M.; Charlton, Steven J.; Henderson, Graeme

    2010-01-01

    We have compared the ability of a number of μ-opioid receptor (MOPr) ligands to activate G proteins with their abilities to induce MOPr phosphorylation, to promote association of arrestin-3 and to cause MOPr internalization. For a model of G protein-coupled receptor (GPCR) activation where all agonists stabilize a single active conformation of the receptor, a close correlation between signaling outputs might be expected. Our results show that overall there is a very good correlation between efficacy for G protein activation and arrestin-3 recruitment, whereas a few agonists, in particular endomorphins 1 and 2, display apparent bias toward arrestin recruitment. The agonist-induced phosphorylation of MOPr at Ser375, considered a key step in MOPr regulation, and agonist-induced internalization of MOPr were each found to correlate well with arrestin-3 recruitment. These data indicate that for the majority of MOPr agonists the ability to induce receptor phosphorylation, arrestin-3 recruitment, and internalization can be predicted from their ability as agonists to activate G proteins. For the prototypic MOPr agonist morphine, its relatively weak ability to induce MOPr internalization can be explained by its low agonist efficacy. PMID:20647394

  7. Acetylcholine Receptor Channels Activated by a Single Agonist Molecule

    PubMed Central

    Jha, Archana; Auerbach, Anthony

    2010-01-01

    Abstract The neuromuscular acetylcholine receptor (AChR) is an allosteric protein that alternatively adopts inactive versus active conformations (R↔R∗). The R∗ shape has a higher agonist affinity and ionic conductance than R. To understand how agonists trigger this gating isomerization, we examined single-channel currents from adult mouse muscle AChRs that isomerize normally without agonists but have only a single site able to use agonist binding energy to motivate gating. We estimated the monoliganded gating equilibrium constant E1 and the energy change associated with the R versus R∗ change in affinity for agonists. AChRs with only one operational binding site gave rise to a single population of currents, indicating that the two transmitter binding sites have approximately the same affinity for the transmitter ACh. The results indicated that E1 ≈ 4.3 × 10−3 with ACh, and ≈1.7 × 10−4 with the partial-agonist choline. From these values and the diliganded gating equilibrium constants, we estimate that the unliganded AChR gating constant is E0 ≈ 6.5 × 10−7. Gating changes the stability of the ligand-protein complex by ∼5.2 kcal/mol for ACh and ∼3.3 kcal/mol for choline. PMID:20441747

  8. Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate CAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of CAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of CAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of CAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of CAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of CAMP by either epinephrine or isoproterenol.

  9. Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.; Cureri, Peter A. (Technical Monitor)

    2002-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of cAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of cAMP by either epinephrine or isoproterenol.

  10. Galectins: new agonists of platelet activation.

    PubMed

    Schattner, Mirta; Rabinovich, Gabriel A

    2013-07-01

    Platelet activation at sites of vascular injury leads to the formation of a hemostatic plug and is crucial for hemostasis. However, uncontrolled platelet activation may lead to the formation of occlusive thrombi. Several soluble or matricellular proteins can activate platelets. In this article, we review recent advances in knowledge of the role of galectins in platelet physiology. In soluble or immobilized form, these endogenous glycan-binding proteins trigger platelet activation through the modulation of discrete signaling pathways. We discuss the role of platelet-galectin interactions not only in hemostasis, but also in chronic inflammation, atherosclerosis and cancer. PMID:23509216

  11. Activation of endplate nicotinic acetylcholine receptors by agonists.

    PubMed

    Auerbach, Anthony

    2015-10-15

    The interaction of a small molecule made in one cell with a large receptor made in another is the signature event of cell signaling. Understanding the structure and energy changes associated with agonist activation is important for engineering drugs, receptors and synapses. The nicotinic acetylcholine receptor (AChR) is a ∼300kD ion channel that binds the neurotransmitter acetylcholine (ACh) and other cholinergic agonists to elicit electrical responses in the central and peripheral nervous systems. This mini-review is in two sections. First, general concepts of skeletal muscle AChR operation are discussed in terms of energy landscapes for conformational change. Second, adult vs. fetal AChRs are compared with regard to interaction energies between ACh and agonist-site side chains, measured by single-channel electrophysiology and molecular dynamics simulations. The five aromatic residues that form the core of each agonist binding site can be divided into two working groups, a triad (led by αY190) that behaves similarly at all sites and a coupled pair (led by γW55) that has a large influence on affinity only in fetal AChRs. Each endplate AChR has 5 homologous subunits, two of α(1) and one each of β, δ, and either γ (fetal) or ϵ (adult). These nicotinic AChRs have only 2 functional agonist binding sites located in the extracellular domain, at αδ and either αγ or αϵ subunit interfaces. The receptor undergoes a reversible, global isomerization between structures called C and O. The C shape does not conduct ions and has a relatively low affinity for ACh, whereas O conducts cations and has a higher affinity. When both agonist sites are empty (filled only with water) the probability of taking on the O conformation (PO) is low, <10(-6). When ACh molecules occupy the agonist sites the C→O opening rate constant and C↔O gating equilibrium constant increase dramatically. Following a pulse of ACh at the nerve-muscle synapse, the endplate current rises rapidly to reach a peak that corresponds to PO ∼0.96. PMID:26206191

  12. Weak value amplified optical activity measurements.

    PubMed

    Pfeifer, Marcel; Fischer, Peer

    2011-08-15

    We present a new form of optical activity measurement based on a modified weak value amplification scheme. It has recently been shown experimentally that the left- and right-circular polarization components refract with slightly different angles of refraction at a chiral interface causing a linearly polarized light beam to split into two. By introducing a polarization modulation that does not give rise to a change in the optical rotation it is possible to differentiate between the two circular polarization components even after post-selection with a linear polarizer. We show that such a modified weak value amplification measurement permits the sign of the splitting and thus the handedness of the optically active medium to be determined. Angular beam separations of Δθ ∼ 1 nanoradian, which corresponds to a circular birefringence of Δn ∼ 1 × 10(-9), could be measured with a relative error of less than 1%. PMID:21935015

  13. Activity-Directed Synthesis with Intermolecular Reactions: Development of a Fragment into a Range of Androgen Receptor Agonists.

    PubMed

    Karageorgis, George; Dow, Mark; Aimon, Anthony; Warriner, Stuart; Nelson, Adam

    2015-11-01

    Activity-directed synthesis (ADS), a novel discovery approach in which bioactive molecules emerge in parallel with associated syntheses, was exploited to develop a weakly binding fragment into novel androgen receptor agonists. Harnessing promiscuous intermolecular reactions of carbenoid compounds enabled highly efficient exploration of chemical space. Four substrates were prepared, yet exploited in 326 reactions to explore diverse chemical space; guided by bioactivity alone, the products of just nine of the reactions were purified to reveal diverse novel agonists with up to 125-fold improved activity. Remarkably, one agonist stemmed from a novel enantioselective transformation; this is the first time that an asymmetric reaction has been discovered solely on the basis of the biological activity of the product. It was shown that ADS is a significant addition to the lead generation toolkit, enabling the efficient and rapid discovery of novel, yet synthetically accessible, bioactive chemotypes. PMID:26358926

  14. Medium chain fatty acids are selective peroxisome proliferator activated receptor (PPAR) γ activators and pan-PPAR partial agonists.

    PubMed

    Liberato, Marcelo Vizoná; Nascimento, Alessandro S; Ayers, Steven D; Lin, Jean Z; Cvoro, Aleksandra; Silveira, Rodrigo L; Martínez, Leandro; Souza, Paulo C T; Saidemberg, Daniel; Deng, Tuo; Amato, Angela Angelica; Togashi, Marie; Hsueh, Willa A; Phillips, Kevin; Palma, Mário Sérgio; Neves, Francisco A R; Skaf, Munir S; Webb, Paul; Polikarpov, Igor

    2012-01-01

    Thiazolidinediones (TZDs) act through peroxisome proliferator activated receptor (PPAR) γ to increase insulin sensitivity in type 2 diabetes (T2DM), but deleterious effects of these ligands mean that selective modulators with improved clinical profiles are needed. We obtained a crystal structure of PPARγ ligand binding domain (LBD) and found that the ligand binding pocket (LBP) is occupied by bacterial medium chain fatty acids (MCFAs). We verified that MCFAs (C8-C10) bind the PPARγ LBD in vitro and showed that they are low-potency partial agonists that display assay-specific actions relative to TZDs; they act as very weak partial agonists in transfections with PPARγ LBD, stronger partial agonists with full length PPARγ and exhibit full blockade of PPARγ phosphorylation by cyclin-dependent kinase 5 (cdk5), linked to reversal of adipose tissue insulin resistance. MCFAs that bind PPARγ also antagonize TZD-dependent adipogenesis in vitro. X-ray structure B-factor analysis and molecular dynamics (MD) simulations suggest that MCFAs weakly stabilize C-terminal activation helix (H) 12 relative to TZDs and this effect is highly dependent on chain length. By contrast, MCFAs preferentially stabilize the H2-H3/β-sheet region and the helix (H) 11-H12 loop relative to TZDs and we propose that MCFA assay-specific actions are linked to their unique binding mode and suggest that it may be possible to identify selective PPARγ modulators with useful clinical profiles among natural products. PMID:22649490

  15. Weakness

    MedlinePlus

    Lack of strength; Muscle weakness ... feel weak but have no real loss of strength. This is called subjective weakness. It may be ... flu. Or, you may have a loss of strength that can be noted on a physical exam. ...

  16. FXR agonist activity of conformationally constrained analogs of GW 4064

    SciTech Connect

    Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y.; Caldwell, Richard D.; Caravella, Justin A.; Chen, Lihong; Creech, Katrina L.; Deaton, David N.; Madauss, Kevin P.; Marr, Harry B.; McFadyen, Robert B.; Miller, Aaron B.; Navas, III, Frank; Parks, Derek J.; Spearing, Paul K.; Todd, Dan; Williams, Shawn P.; Wisely, G. Bruce

    2010-09-27

    Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

  17. Cold Suppresses Agonist-induced Activation of TRPV1

    PubMed Central

    Chung, M.-K.; Wang, S.

    2011-01-01

    Cold therapy is frequently used to reduce pain and edema following acute injury or surgery such as tooth extraction. However, the neurobiological mechanisms of cold therapy are not completely understood. Transient receptor potential vanilloid 1 (TRPV1) is a capsaicin- and heat-gated nociceptive ion channel implicated in thermosensation and pathological pain under conditions of inflammation or injury. Although capsaicin-induced nociception, neuropeptide release, and ionic currents are suppressed by cold, it is not known if cold suppresses agonist-induced activation of recombinant TRPV1. We demonstrate that cold strongly suppressed the activation of recombinant TRPV1 by multiple agonists and capsaicin-evoked currents in trigeminal ganglia neurons under normal and phosphorylated conditions. Cold-induced suppression was partially impaired in a TRPV1 mutant that lacked heat-mediated activation and potentiation. These results suggest that cold-induced suppression of TRPV1 may share a common molecular basis with heat-induced potentiation, and that allosteric inhibition may contribute, in part, to the cold-induced suppression. We also show that combination of cold and a specific antagonist of TRPV1 can produce an additive suppression. Our results provide a mechanistic basis for cold therapy and may enhance anti-nociceptive approaches that target TRPV1 for managing pain under inflammation and tissue injury, including that from tooth extraction. PMID:21666106

  18. Synthesis and biological activities of indolizine derivatives as alpha-7 nAChR agonists.

    PubMed

    Xue, Yu; Tang, Jingshu; Ma, Xiaozhuo; Li, Qing; Xie, Bingxue; Hao, Yuchen; Jin, Hongwei; Wang, Kewei; Zhang, Guisen; Zhang, Liangren; Zhang, Lihe

    2016-06-10

    Human α7 nicotinic acetylcholine receptor (nAChR) is a promising therapeutic target for the treatment of schizophrenia accompanied with cognitive impairment. Herein, we report the synthesis and agonistic activities of a series of indolizine derivatives targeting to α7 nAChR. The results show that all synthesized compounds have affinity to α7 nAChR and some give strong agonistic activity, particularly most active agonists show higher potency than control EVP-6124. The docking and structure-activity relationship studies provide insights to develop more potent novel α7 nAChR agonists. PMID:26994846

  19. Fine tuning of agonistic/antagonistic activity for vitamin D receptor by 22-alkyl chain length of ligands: 22S-Hexyl compound unexpectedly restored agonistic activity.

    PubMed

    Anami, Yasuaki; Sakamaki, Yuta; Itoh, Toshimasa; Inaba, Yuka; Nakabayashi, Makoto; Ikura, Teikichi; Ito, Nobutoshi; Yamamoto, Keiko

    2015-11-15

    1?,25-Dihydroxyvitamin D3 exerts its actions by binding to vitamin D receptor (VDR). We are continuing the study related to the alteration of pocket structure of VDR by 22-alkyl substituent of ligands and the relationships between the alteration and agonistic/antagonistic activity. Previously we reported that compounds 2 (22-H), 3 (22S-Et), and 4 (22S-Bu) are VDR agonist, partial agonist and antagonist, respectively. Here, we describe the synthesis and biological evaluation of 22S-hexyl analog 5 (22S-Hex), which was designed to be a stronger VDR antagonist than 4. Unexpectedly, 5 showed partial agonistic but not antagonistic activity when bound to VDR, indicating that it is not necessarily true that the bulkier the side chain is, the stronger the antagonistic activity will be. X-ray crystallographic analysis of the VDR-ligand-binding domain (VDR-LBD) accommodating compound 5 indicated that the partial agonist activity of 5 is dependent on the mixed population of the agonistic and antagonistic conformations. Binding of compound 5 may not bring the complex into the only antagonistic conformation due to the large conformational change of the VDR-LBD. From this study it was found that fine tuning of agonistic/antagonistic activity for VDR is possible by 22-alkyl chain length of ligands. PMID:26515040

  20. Theory of partial agonist activity of steroid hormones

    PubMed Central

    Chow, Carson C.; Ong, Karen M.; Kagan, Benjamin; Simons, S. Stoney

    2015-01-01

    The different amounts of residual partial agonist activity (PAA) of antisteroids under assorted conditions have long been useful in clinical applications but remain largely unexplained. Not only does a given antagonist often afford unequal induction for multiple genes in the same cell but also the activity of the same antisteroid with the same gene changes with variations in concentration of numerous cofactors. Using glucocorticoid receptors as a model system, we have recently succeeded in constructing from first principles a theory that accurately describes how cofactors can modulate the ability of agonist steroids to regulate both gene induction and gene repression. We now extend this framework to the actions of antisteroids in gene induction. The theory shows why changes in PAA cannot be explained simply by differences in ligand affinity for receptor and requires action at a second step or site in the overall sequence of reactions. The theory also provides a method for locating the position of this second site, relative to a concentration limited step (CLS), which is a previously identified step in glucocorticoid-regulated transactivation that always occurs at the same position in the overall sequence of events of gene induction. Finally, the theory predicts that classes of antagonist ligands may be grouped on the basis of their maximal PAA with excess added cofactor and that the members of each class differ by how they act at the same step in the overall gene induction process. Thus, this theory now makes it possible to predict how different cofactors modulate antisteroid PAA, which should be invaluable in developing more selective antagonists. PMID:25984562

  1. The murine neutrophil NLRP3 inflammasome is activated by soluble but not particulate or crystalline agonists.

    PubMed

    Chen, Kaiwen W; Bezbradica, Jelena S; Groß, Christina J; Wall, Adam A; Sweet, Matthew J; Stow, Jennifer L; Schroder, Kate

    2016-04-01

    Neutrophils express pattern recognition receptors (PRRs) and regulate immune responses via PRR-dependent cytokine production. An emerging theme is that neutrophil PRRs often exhibit cell type-specific adaptations in their signalling pathways. This prompted us to examine inflammasome signalling by the PRR NLRP3 in murine neutrophils, in comparison to well-established NLRP3 signalling pathways in macrophages. Here, we demonstrate that while murine neutrophils can indeed signal via the NLRP3 inflammasome, neutrophil NLRP3 selectively responds to soluble agonists but not to the particulate/crystalline agonists that trigger NLRP3 activation in macrophages via phagolysosomal rupture. In keeping with this, alum did not trigger IL-1β production from human PMN, and the lysosomotropic peptide Leu-Leu-OMe stimulated only weak NLRP3-dependent IL-1β production from murine neutrophils, suggesting that lysosomal rupture is not a strong stimulus for NLRP3 activation in neutrophils. We validated our in vitro findings for poor neutrophil NLRP3 responses to particles in vivo, where we demonstrated that neutrophils do not significantly contribute to alum-induced IL-1β production in mice. In all, our studies highlight that myeloid cell identity and the nature of the danger signal can strongly influence signalling by a single PRR, thus shaping the nature of the resultant immune response. PMID:27062120

  2. Sustained wash-resistant receptor activation responses of GPR119 agonists.

    PubMed

    Hothersall, J Daniel; Bussey, Charlotte E; Brown, Alastair J; Scott, James S; Dale, Ian; Rawlins, Philip

    2015-09-01

    G protein-coupled receptor 119 (GPR119) is involved in regulating metabolic homoeostasis, with GPR119 agonists targeted for the treatment of type-2 diabetes and obesity. Using the endogenous agonist oleoylethanolamide and a number of small molecule synthetic agonists we have investigated the temporal dynamics of receptor signalling. Using both a dynamic luminescence biosensor-based assay and an endpoint cAMP accumulation assay we show that agonist-driven desensitization is not a major regulatory mechanism for GPR119 despite robust activation responses, regardless of the agonist used. Temporal analysis of the cAMP responses demonstrated sustained signalling resistant to washout for some, but not all of the agonists tested. Further analysis indicated that the sustained effects of one synthetic agonist AR-231,453 were consistent with a role for slow dissociation kinetics. In contrast, the sustained responses to MBX-2982 and AZ1 appeared to involve membrane deposition. We also detect wash-resistant responses to AR-231,453 at the level of physiologically relevant responses in an endogenous expression system (GLP-1 secretion in GLUTag cells). In conclusion, our findings indicate that in a recombinant expression system GPR119 activation is sustained, with little evidence of pronounced receptor desensitization, and for some ligands persistent agonist responses continue despite removal of excess agonist. This provides novel understanding of the temporal responses profiles of potential drug candidates targetting GPR119, and highlights the importance of carefully examining the the mechanisms through which GPCRs generate sustained responses. PMID:26101059

  3. Agonist-induced platelet procoagulant activity requires shear and a Rac1-dependent signaling mechanism

    PubMed Central

    Delaney, Michael Keegan; Liu, Junling; Kim, Kyungho; Shen, Bo; Stojanovic-Terpo, Aleksandra; Zheng, Yi; Cho, Jaehyung

    2014-01-01

    Activated platelets facilitate blood coagulation by exposing phosphatidylserine (PS) and releasing microvesicles (MVs). However, the potent physiological agonists thrombin and collagen poorly induce PS exposure when a single agonist is used. To obtain a greater procoagulant response, thrombin is commonly used in combination with glycoprotein VI agonists. However, even under these conditions, only a percentage of platelets express procoagulant activity. To date, it remains unclear why platelets poorly expose PS even when stimulated with multiple agonists and what the signaling pathways are of soluble agonist-induced platelet procoagulant activity. Here we show that physiological levels of shear present in blood significantly enhance agonist-induced platelet PS exposure and MV release, enabling low doses of a single agonist to induce full-scale platelet procoagulant activity. PS exposed on the platelet surface was immediately released as MVs, revealing a tight coupling between the 2 processes under shear. Using platelet-specific Rac1−/− mice, we discovered that Rac1 plays a common role in mediating the low-dose agonist-induced procoagulant response independent of platelet aggregation, secretion, and the apoptosis pathway. Platelet-specific Rac1 function was not only important for coagulation in vitro but also for fibrin accumulation in vivo following laser-induced arteriolar injury. PMID:25079357

  4. Peroxisome proliferator-activated receptor-delta agonist ameliorated inflammasome activation in nonalcoholic fatty liver disease

    PubMed Central

    Lee, Hyun Jung; Yeon, Jong Eun; Ko, Eun Jung; Yoon, Eileen L; Suh, Sang Jun; Kang, Keunhee; Kim, Hae Rim; Kang, Seoung Hee; Yoo, Yang Jae; Je, Jihye; Lee, Beom Jae; Kim, Ji Hoon; Seo, Yeon Seok; Yim, Hyung Joon; Byun, Kwan Soo

    2015-01-01

    AIM: To evaluate the inflammasome activation and the effect of peroxisome proliferator-activated receptors (PPAR)-δ agonist treatment in nonalcoholic fatty liver disease (NAFLD) models. METHODS: Male C57BL/6J mice were classified according to control or high fat diet (HFD) with or without PPAR-δ agonist (GW) over period of 12 wk [control, HFD, HFD + lipopolysaccharide (LPS), HFD + LPS + GW group]. HepG2 cells were exposed to palmitic acid (PA) and/or LPS in the absence or presence of GW. RESULTS: HFD caused glucose intolerance and hepatic steatosis. In mice fed an HFD with LPS, caspase-1 and interleukin (IL)-1β in the liver were significantly increased. Treatment with GW ameliorated the steatosis and inhibited overexpression of pro-inflammatory cytokines. In HepG2 cells, PA and LPS treatment markedly increased mRNA of several nucleotide-binding and oligomerization domain-like receptor family members (NLRP3, NLRP6, and NLRP10), caspase-1 and IL-1β. PA and LPS also exaggerated reactive oxygen species production. All of the above effects of PA and LPS were reduced by GW. GW also enhanced the phosphorylation of AMPK-α. CONCLUSION: PPAR-δ agonist reduces fatty acid-induced inflammation and steatosis by suppressing inflammasome activation. Targeting the inflammasome by the PPAR-δ agonist may have therapeutic implication for NAFLD. PMID:26668503

  5. Selective peroxisome proliferator-activated receptor α modulators (SPPARMα): the next generation of peroxisome proliferator-activated receptor α-agonists.

    PubMed

    Fruchart, Jean-Charles

    2013-01-01

    Dyslipidemia is a major risk factor for cardiovascular (CV) disease - the primary cause of death, worldwide. Although reducing levels of low-density lipoprotein-cholesterol can significantly reduce CV risk, a high level of residual risk persists, especially in people with obesity-related conditions, such as metabolic syndrome and type 2 diabetes mellitus. Peroxisome proliferator-activated receptor alpha- (PPARα-) agonists (e.g. fibrates), play a central role in the reduction of macro- and microvascular risk in these patients. However, the currently available fibrates are weak (PPARα-agonists) with limited efficacy due to dose-related adverse effects. To address this problem, a new generation of highly potent and selective PPARα-modulators (SPPARMα) is being developed that separate the benefits of the PPARα-agonists from their unwanted side effects. Among these, aleglitazar (a dual PPARα/γ agonist) and GFT505 (a dual PPAR α/δ agonist) have recently entered late-phase development. Although both compounds are more potent PPARα-activators than fenofibrate in vitro, only aleglitezar is more effective in lowering triglycerides and raising high-density lipoprotein-cholesterol (HDL-C) in humans. However, it is also associated with a potential risk of adverse effects. More recently, a highly potent, specific PPARα-agonist (K-877) has emerged with SPPARMα characteristics. Compared to fenofibrate, K-877 has more potent PPARα-activating efficacy in vitro, greater effects on triglycerides- and HDL-C levels in humans, and a reduced risk of adverse effects. If successful, K-877 has the potential to supersede the fibrates as the treatment of choice for patients with residual CV risk associated with metabolic syndrome and type 2 diabetes. PMID:23721199

  6. Access to 7?-analogs of codeine with mixed ?/? agonist activity via 6,7-?-epoxide opening.

    PubMed

    Magnus, Philip; Ghavimi, Bahman; Coe, Jotham W

    2013-09-01

    (-)-Codeine 1 was converted into previously unknown 7?-methyl-7,8-dihydrocodeine/morphine derivatives such as 13 via classical diaxial opening of ?-epoxide 3. Several analogs exhibited dual ?/?-agonist activity. PMID:23880538

  7. Antidepressant-like activity of 5-HT1A agonists measured with the forced swim test.

    PubMed

    Wieland, S; Lucki, I

    1990-01-01

    This study examined the abilities of 5-hydroxytryptamine (5-HT) agonists with varying selectivity for different subtypes of 5-HT receptors to produce antidepressant-like behavioral effects in the forced swim test in rats. The 5-HT1A agonists 8-OH-DPAT (0.125-1.0 mg/kg, SC) and tandospirone (SM-3997) (5-20 mg/kg, SC) both produced dose-related decreases in immobility time following subchronic treatment in rats. These effects were similar to those of the tricyclic antidepressants imipramine (5-15 mg/kg) and desipramine (5-15 mg/kg). In addition, the 5-HT1A agonists, buspirone (20 mg/kg), gepirone (20 mg/kg) and ipsapirone (10 and 20 mg/kg) demonstrated antidepressant-like effects. Other groups of rats treated subchronically with each of the 5-HT1A agonists or antidepressants showed no increase in locomotor activity, so that general changes in activity could not account for the reduction of immobility time in the forced swim test. 5-HT agonists selective for other receptor subtypes, such as the 5-HT1B/1C agonist m-CPP (5 mg/kg) and the 5-HT2/1C agonist DOB (1 mg/kg), were not effective in this behavioral test. The benzodiazepine diazepam (5 mg/kg) also failed to reduce immobility time, suggesting that anxiolytic properties of 5-HT1A agonists did not mediate this behavioral effect. A common metabolite of some of the 5-HT1A agonists, 1-PP, was ineffective in reducing immobility time. The stimulant d-amphetamine (2 mg/kg) significantly reduced immobility time but also significantly increased locomotor activity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1975107

  8. Activation of Protease Activated Receptor 2 by Exogenous Agonist Exacerbates Early Radiation Injury in Rat Intestine

    SciTech Connect

    Wang Junru; Boerma, Marjan; Kulkarni, Ashwini; Hollenberg, Morley D.; Hauer-Jensen, Martin

    2010-07-15

    Purpose: Protease-activated receptor-2 (PAR{sub 2}) is highly expressed throughout the gut and regulates the inflammatory, mitogenic, fibroproliferative, and nociceptive responses to injury. PAR{sub 2} is strikingly upregulated and exhibits increased activation in response to intestinal irradiation. We examined the mechanistic significance of radiation enteropathy development by assessing the effect of exogenous PAR{sub 2} activation. Methods and Materials: Rat small bowel was exposed to localized single-dose radiation (16.5 Gy). The PAR{sub 2} agonist (2-furoyl-LIGRLO-NH{sub 2}) or vehicle was injected intraperitoneally daily for 3 days before irradiation (before), for 7 days after irradiation (after), or both 3 days before and 7 days after irradiation (before-after). Early and delayed radiation enteropathy was assessed at 2 and 26 weeks after irradiation using quantitative histologic examination, morphometry, and immunohistochemical analysis. Results: The PAR{sub 2} agonist did not elicit changes in the unirradiated (shielded) intestine. In contrast, in the irradiated intestine procured 2 weeks after irradiation, administration of the PAR{sub 2} agonist was associated with more severe mucosal injury and increased intestinal wall thickness in all three treatment groups (p <.05) compared with the vehicle-treated controls. The PAR{sub 2} agonist also exacerbated the radiation injury score, serosal thickening, and mucosal inflammation (p <.05) in the before and before-after groups. The short-term exogenous activation of PAR{sub 2} did not affect radiation-induced intestinal injury at 26 weeks. Conclusion: The results of the present study support a role for PAR{sub 2} activation in the pathogenesis of early radiation-induced intestinal injury. Pharmacologic PAR{sub 2} antagonists might have the potential to reduce the intestinal side effects of radiotherapy and/or as countermeasures in radiologic accidents or terrorism scenarios.

  9. The Renoprotective Actions of Peroxisome Proliferator-Activated Receptors Agonists in Diabetes

    PubMed Central

    Thomas, M. C.; Jandeleit-Dahm, K. A.; Tikellis, C.

    2012-01-01

    Pharmaceutical agonists of peroxisome proliferator-activated receptors (PPARs) are widely used in the management of type 2 diabetes, chiefly as lipid-lowering agents and oral hypoglycaemic agents. Although most of the focus has been placed on their cardiovascular effects, both positive and negative, these agents also have significant renoprotective actions in the diabetic kidney. Over and above action on metabolic control and effects on blood pressure, PPAR agonists also appear to have independent effects on a number of critical pathways that are implicated in the development and progression of diabetic kidney disease, including oxidative stress, inflammation, hypertrophy, and podocyte function. This review will examine these direct and indirect actions of PPAR agonists in the diabetic kidney and explore recent findings of clinical trials of PPAR agonists in patients with diabetes. PMID:22448165

  10. Functional activation of beta-adrenergic receptors by thiols in the presence or absence of agonists.

    PubMed

    Pedersen, S E; Ross, E M

    1985-11-15

    Treatment of beta-adrenergic receptor with dithiothreitol (DTT) or other thiol compounds caused its functional activation in the presence or absence of agonist ligands. Such activation was observed in reconstituted unilamellar phospholipid vesicles that contained beta-adrenergic receptors, purified to greater than or equal to 95% homogeneity from turkey erythrocyte plasma membranes, and the stimulatory GTP-binding protein of the adenylate cyclase system (Gs) purified from rabbit liver. Incubation of the vesicles with 2-10 mM DTT at 0 degrees C for 1 h increased the rate (4-5-fold) and the extent (3-4-fold) of activation of Gs by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) binding, an effect about equivalent to the addition of beta-adrenergic agonists. Treatment with DTT also markedly potentiated the ability of agonists to stimulate GTP gamma S binding, increasing the initial rate about 10-fold. DTT treatment was as effective as agonist in stimulating GTPase activity, and maximal stimulation was obtained when DTT-treated vesicles were assayed in the presence of agonist. Other thiol compounds produced effects similar to those of DTT but were at least 10-fold less potent. Stimulation of GTP gamma S binding or GTPase activity required active receptor, and treatment of the receptor with DTT prior to reconstitution also increased its efficacy. There was no effect of DTT on Gs alone. Thus, the site of action of DTT appears to be on the beta-adrenergic receptor itself, and the reduction of disulfides and the binding of agonist act synergistically to activate the receptor. DTT treatment made the receptor more labile to thermal denaturation. Inclusion of cholesterol or cholesteryl-hemisuccinate (5-25%) in the vesicles protected the reduced receptor against such denaturation and enhanced its recovery during reconstitution. No effect of cholesterol or cholesteryl-hemisuccinate was observed on the stability of the nonreduced receptor, which was comparable to that observed in native membranes. PMID:2997196

  11. The atypical antidepressant mianserin exhibits agonist activity at κ-opioid receptors

    PubMed Central

    Olianas, Maria C; Dedoni, Simona; Onali, Pierluigi

    2012-01-01

    BACKGROUND AND PURPOSE Antidepressants are known to interact with the opioid system through mechanisms not completely understood. We previously reported that tricyclic antidepressants act as agonists at distinct opioid receptors. Here, we investigated the effect of the atypical antidepressant mianserin at cloned and native opioid receptors. EXPERIMENTAL APPROACH Effects of mianserin were examined in CHO cells transfected with human opioid receptors, C6 glioma cells and rat brain membranes by the use of radioligand binding and functional assays including the stimulation of [35S]GTPγS binding and MAPK phosphorylation. KEY RESULTS Mianserin displayed 12- and 18-fold higher affinity for κ- than µ- and δ-opioid receptors respectively. In [35S]GTPγS assays, mianserin selectively activated κ-opioid receptors. The agonist activity was antagonized by the selective κ-opioid blocker nor-binaltorphimine (nor-BNI). The mianserin analogue mirtazapine also displayed κ-opioid agonist activity. Mianserin and mirtazapine increased ERK1/2 phosphorylation in CHO cells expressing κ-opioid receptors and C6 cells, and these effects were antagonized by nor-BNI. In rat striatum and nucleus accumbens, mianserin stimulated [35S]GTPγS binding in a nor-BNI-sensitive manner with maximal effects lower than those of the full κ-opioid agonists (–)-U50,488 and dynorphin A. When combined, mianserin antagonized the effects of the full κ-opioid receptor agonists in [35S]GTPγS assays and reduced the stimulation of p38 MAPK and ERK1/2 phosphorylation by dynorphin A. CONCLUSIONS AND IMPLICATIONS In different cell systems, mianserin directly activates κ-opioid receptors, displaying partial agonist activity at brain receptors. Thus, this property appears to be a common feature of different classes of antidepressants. PMID:22708686

  12. Design and synthesis of silicon-containing fatty acid amide derivatives as novel peroxisome proliferator-activated receptor (PPAR) agonists.

    PubMed

    Kajita, Daisuke; Nakamura, Masaharu; Matsumoto, Yotaro; Ishikawa, Minoru; Hashimoto, Yuichi; Fujii, Shinya

    2015-08-15

    We recently reported that diphenylsilane structure can function as a cis-stilbene mimetic. Here, we investigate whether silyl functionality can also serve as a mimetic of aliphatic cis-olefin. We designed and synthesized various silyl derivatives of oleoylethanolamide (OEA: 8), an endogenous cis-olefin-containing PPARα agonist, and evaluated their PPARα/δ/γ agonistic activity. We found that diethylsilyl derivative 20 exhibited PPARα/δ agonistic activity, and we also obtained a PPARδ-selective agonist, 32. Our results suggest that incorporation of silyl functionality is a useful option for structural development of biologically active compounds. PMID:26071639

  13. Melanocortin 1 receptor agonist protects podocytes through catalase and RhoA activation.

    PubMed

    Elvin, Johannes; Buvall, Lisa; Lindskog Jonsson, Annika; Granqvist, Anna; Lassén, Emelie; Bergwall, Lovisa; Nyström, Jenny; Haraldsson, Börje

    2016-05-01

    Drugs containing adrenocorticotropic hormone have been used as therapy for patients with nephrotic syndrome. We have previously shown that adrenocorticotropic hormone and a selective agonist for the melanocortin 1 receptor (MC1R) exert beneficial actions in experimental membranous nephropathy with reduced proteinuria, reduced oxidative stress, and improved glomerular morphology and function. Our hypothesis is that MC1R activation in podocytes elicits beneficial effects by promoting stress fibers and maintaining podocyte viability. To test the hypothesis, we cultured podocytes and used highly specific agonists for MC1R. Podocytes were subjected to the nephrotic-inducing agent puromycin aminonucleoside, and downstream effects of MC1R activation on podocyte survival, antioxidant defense, and cytoskeleton dynamics were studied. To increase the response and enhance intracellular signals, podocytes were transduced to overexpress MC1R. We showed that puromycin promotes MC1R expression in podocytes and that activation of MC1R promotes an increase of catalase activity and reduces oxidative stress, which results in the dephosphorylation of p190RhoGAP and formation of stress fibers through RhoA. In addition, MC1R agonists protect against apoptosis. Together, these mechanisms protect the podocyte against puromycin. Our findings strongly support the hypothesis that selective MC1R-activating agonists protect podocytes and may therefore be useful to treat patients with nephrotic syndromes commonly considered as podocytopathies. PMID:26887829

  14. Characterization of active and inactive states of CB1 receptor and the differential binding state modulation by cannabinoid agonists, antagonists and inverse agonists.

    PubMed

    Gullapalli, Srinivas; Amrutkar, Dipak; Gupta, Sangeetha; Kandadi, Machender R; Kumar, Hemant; Gandhi, Maulik; Karande, Vikas; Narayanan, Shridhar

    2010-06-01

    Cannabinoid 1 (CB1) receptors have the ability to change conformation between active (R*) and inactive (R) receptor states. Herein, we further characterize these receptor states using series of saturation radioligand binding studies and their differential displacement binding by various CB1 receptor ligands. Binding experiments were carried out in naïve rat/dog whole brain membranes using radioligands [(3)H]CP55,940 (for R* state) & [(3)H]SR141716A (both R* and R states) and various agonist, antagonist & inverse agonist ligands at CB1 receptors. In the saturation binding experiments, of the total number of CB1 receptor binding sites (R* + R) in the rat and dog whole brain membranes, only about 18.3 and 11.6% were in the active (R*) state recognized by [(3)H]CP55,940, respectively. In the competitive binding studies, all the CB1 receptor agonists investigated had significantly very high affinity for the active R* state recognized by [(3)H]CP55,940 and lower affinity for the inactive R state mainly recognized by [(3)H]SR141716A in the presence of a non-hydrolyzable analogue of GTP [Gpp(NH)p]. In contrast, various CB1 receptor antagonists/inverse agonists had similar nanomolar affinities at both [(3)H]CP55,940 and [(3)H]SR141716A recognized binding states. These results clearly characterize the significant differences between the active R* and inactive R binding states of CB1 receptors in naive rat and dog brain. In addition, these results also demonstrates that the CB1 agonists and antagonists/inverse agonists can be differentiated by their relative affinities at active (R*) and inactive (R) binding states of the CB1 receptor. PMID:20214912

  15. Modulation Effect of Peroxisome Proliferator-Activated Receptor Agonists on Lipid Droplet Proteins in Liver

    PubMed Central

    Zhu, Yun-Xia; Zhang, Ming-Liang; Zhong, Yuan; Wang, Chen; Jia, Wei-Ping

    2016-01-01

    Peroxisome proliferator-activated receptor (PPAR) agonists are used for treating hyperglycemia and type 2 diabetes. However, the mechanism of action of these agonists is still under investigation. The lipid droplet-associated proteins FSP27/CIDEC and LSDP5, regulated directly by PPARγ and PPARα, are associated with hepatic steatosis and insulin sensitivity. Here, we evaluated the expression levels of FSP27/CIDEC and LSDP5 and the regulation of these proteins by consumption of a high-fat diet (HFD) or administration of PPAR agonists. Mice with diet-induced obesity were treated with the PPARγ or PPARα agonist, pioglitazone or fenofibrate, respectively. Liver tissues from db/db diabetic mice and human were also collected. Interestingly, FSP27/CIEDC was expressed in mouse and human livers and was upregulated in obese C57BL/6J mice. Fenofibrate treatment decreased hepatic triglyceride (TG) content and FSP27/CIDEC protein expression in mice fed an HFD diet. In mice, LSDP5 was not detected, even in the context of insulin resistance or treatment with PPAR agonists. However, LSDP5 was highly expressed in humans, with elevated expression observed in the fatty liver. We concluded that fenofibrate greatly decreased hepatic TG content and FSP27/CIDEC protein expression in mice fed an HFD, suggesting a potential regulatory role for fenofibrate in the amelioration of hepatic steatosis. PMID:26770990

  16. Orally active ghrelin receptor inverse agonists and their actions on a rat obesity model.

    PubMed

    Takahashi, Bitoku; Funami, Hideaki; Iwaki, Takehiko; Maruoka, Hiroshi; Shibata, Makoto; Koyama, Makoto; Nagahira, Asako; Kamiide, Yoshiyuki; Kanki, Satomi; Igawa, Yoshiyuki; Muto, Tsuyoshi

    2015-08-01

    A series of 2-alkylamino nicotinamide analogs was prepared as orally active ghrelin receptor (ghrelinR) inverse agonists. Starting from compound 1, oral bioavailability was improved by modifying metabolically unstable sites and reducing molecular weight. Brain-permeable compound 33 and compound 24 with low brain permeability were tested in rat models of obesity; 30 mg/kg of compound 33 suppressed weight gain. PK/PD analysis revealed that the anti-obesity effect of ghrelinR inverse agonists depends on their brain concentrations. PMID:26100441

  17. NICOTINE EFFECTS ON THE ACTIVITY OF MICE EXPOSED PRENATALLY TO THE NICOTINIC AGONIST ANATOXIN-A.

    EPA Science Inventory

    Considerable research has shown long-lasting effects of early exposure in experimental animals to nicotine. Anatoxin-a is produced by cyanobacteria and has been shown to be a potent nicotinic agonist. This experiment evaluated the motor activity of adult mice, and their respons...

  18. Accessory Cell Mediated Activation of Porcine NK Cells by TLR7 and TLR8 Agonists

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The induction of innate immune responses by toll-like receptor (TLR) agonists is the subject of intense investigation in many different species. In large part, this reflects the potential of such compounds to be effective vaccine adjuvants. For that reason, we analyzed the activation of innate cells...

  19. Activation of muscle nicotinic acetylcholine receptor channels by nicotinic and muscarinic agonists

    PubMed Central

    Akk, Gustav; Auerbach, Anthony

    1999-01-01

    The dose-response parameters of recombinant mouse adult neuromuscular acetylcholine receptor channels (nAChR) activated by carbamylcholine, nicotine, muscarine and oxotremorine were measured. Rate constants for agonist association and dissociation, and channel opening and closing, were estimated from single-channel kinetic analysis.The dissociation equilibrium constants were (mM): ACh (0.16)carbamylcholine (5.1)>oxotremorine M (0.6)>nicotine (0.5)>muscarine (0.15).Rat neuronal α4β2 nAChR can be activated by all of the agonists. However, detailed kinetic analysis was impossible because the recordings lacked clusters representing the activity of a single receptor complex. Thus, the number of channels in the patch was unknown and the activation rate constants could not be determined.Considering both receptor affinity and agonist efficacy, muscarine and oxotremorine are significant agonists of muscle-type nAChR. The results are discussed in terms of structure-function relationships at the nAChR transmitter binding site. PMID:10602325

  20. Distinct activities of GABA agonists at synaptic- and extrasynaptic-type GABAA receptors.

    PubMed

    Mortensen, Martin; Ebert, Bjarke; Wafford, Keith; Smart, Trevor G

    2010-04-15

    The activation characteristics of synaptic and extrasynaptic GABA(A) receptors are important for shaping the profile of phasic and tonic inhibition in the central nervous system, which will critically impact on the activity of neuronal networks. Here, we study in isolation the activity of three agonists, GABA, muscimol and 4,5,6,7-tetrahydoisoxazolo[5,4-c]pyridin-3(2H)-one (THIP), to further understand the activation profiles of alpha 1 beta 3 gamma 2, alpha 4 beta 3 gamma 2 and alpha 4 beta 3 delta receptors that typify synaptic- and extrasynaptic-type receptors expressed in the hippocampus and thalamus. The agonists display an order of potency that is invariant between the three receptors, which is reliant mostly on the agonist dissociation constant. At delta subunit-containing extrasynaptic-type GABA(A) receptors, both THIP and muscimol additionally exhibited, to different degrees, superagonist behaviour. By comparing whole-cell and single channel currents induced by the agonists, we provide a molecular explanation for their different activation profiles. For THIP at high concentrations, the unusual superagonist behaviour on alpha 4 beta 3 delta receptors is a consequence of its ability to increase the duration of longer channel openings and their frequency, resulting in longer burst durations. By contrast, for muscimol, moderate superagonist behaviour was caused by reduced desensitisation of the extrasynaptic-type receptors. The ability to specifically increase the efficacy of receptor activation, by selected exogenous agonists over that obtained with the natural transmitter, may prove to be of therapeutic benefit under circumstances when synaptic inhibition is compromised or dysfunctional. PMID:20176630

  1. K+ efflux agonists induce NLRP3 inflammasome activation independently of Ca2+ signaling1

    PubMed Central

    Katsnelson, Michael A.; Rucker, L. Graham; Russo, Hana M.; Dubyak, George R.

    2015-01-01

    Perturbation of intracellular ion homeostasis is a major cellular stress signal for activation of NLRP3 inflammasome signaling that results in caspase-1 mediated production of IL-1β and pyroptosis. However, the relative contributions of decreased cytosolic [K+] versus increased cytosolic [Ca2+] remain disputed and incompletely defined. We investigated roles for elevated cytosolic [Ca2+] in NLRP3 activation and downstream inflammasome signaling responses in primary murine dendritic cells and macrophages in response to two canonical NLRP3 agonists (ATP and nigericin) that facilitate primary K+ efflux by mechanistically distinct pathways or the lysosome-destabilizing agonist Leu-Leu-O-methyl ester (LLME). The study provides three major findings relevant to this unresolved area of NLRP3 regulation. First, increased cytosolic [Ca2+] was neither a necessary nor sufficient signal for the NLRP3 inflammasome cascade during activation by endogenous ATP-gated P2X7 receptor channels, the exogenous bacterial ionophore nigericin, or the lysosomotropic agent LLME. Second, agonists for three Ca2+-mobilizing G protein-coupled receptors (formyl peptide receptor/FPR; P2Y2 purinergic receptor/P2Y2R; calcium-sensing receptor/CaSR) expressed in murine dendritic cells were ineffective as activators of rapidly induced NLRP3 signaling when directly compared to the K+ efflux agonists. Third, the intracellular Ca2+ buffer, BAPTA, and the channel blocker, 2-aminoethoxydiphenyl borate (2-APB), widely used reagents for disruption of Ca2+-dependent signaling pathways, strongly suppressed nigericin-induced NLRP3 inflammasome signaling via mechanisms dissociated from their canonical or expected effects on Ca2+ homeostasis. The results indicate that the ability of K+ efflux agonists to activate NLRP3 inflammasome signaling can be dissociated from changes in cytosolic [Ca2+] as a necessary or sufficient signal. PMID:25762778

  2. Natural product agonists of peroxisome proliferator-activated receptor gamma (PPARγ): a review

    PubMed Central

    Wang, Limei; Waltenberger, Birgit; Pferschy-Wenzig, Eva-Maria; Blunder, Martina; Liu, Xin; Malainer, Clemens; Blazevic, Tina; Schwaiger, Stefan; Rollinger, Judith M.; Heiss, Elke H.; Schuster, Daniela; Kopp, Brigitte; Bauer, Rudolf; Stuppner, Hermann; Dirsch, Verena M.; Atanasov, Atanas G.

    2014-01-01

    Agonists of the nuclear receptor PPARγ are therapeutically used to combat hyperglycaemia associated with the metabolic syndrome and type 2 diabetes. In spite of being effective in normalization of blood glucose levels, the currently used PPARγ agonists from the thiazolidinedione type have serious side effects, making the discovery of novel ligands highly relevant. Natural products have proven historically to be a promising pool of structures for drug discovery, and a significant research effort has recently been undertaken to explore the PPARγ-activating potential of a wide range of natural products originating from traditionally used medicinal plants or dietary sources. The majority of identified compounds are selective PPARγ modulators (SPPARMs), transactivating the expression of PPARγ-dependent reporter genes as partial agonists. Those natural PPARγ ligands have different binding modes to the receptor in comparison to the full thiazolidinedione agonists, and on some occasions activate in addition PPARα (e.g. genistein, biochanin A, sargaquinoic acid, sargahydroquinoic acid, resveratrol, amorphastilbol) or the PPARγ-dimer partner retinoid X receptor (RXR; e.g. the neolignans magnolol and honokiol). A number of in vivo studies suggest that some of the natural product activators of PPARγ (e.g. honokiol, amorfrutin 1, amorfrutin B, amorphastilbol) improve metabolic parameters in diabetic animal models, partly with reduced side effects in comparison to full thiazolidinedione agonists. The bioactivity pattern as well as the dietary use of several of the identified active compounds and plant extracts warrants future research regarding their therapeutic potential and the possibility to modulate PPARγ activation by dietary interventions or food supplements. PMID:25083916

  3. Inverse agonist activity of selected ligands of the cysteinyl-leukotriene receptor 1.

    PubMed

    Dupré, Denis J; Le Gouill, Christian; Gingras, Denis; Rola-Pleszczynski, Marek; Stanková, Jana

    2004-04-01

    Cysteinyl leukotrienes (CysLTs) are associated with several inflammatory processes, including asthma. Due to this association, considerable effort has been invested in the development of antagonists to the CysLT receptors (CysLT(1)R). Many of these molecules have been shown to specifically interact with CysLT(1)R, but little is known about their impact on the conformation of the receptor and its activity. We were especially interested in possible inverse agonist activity of the antagonists. Using a constitutively active mutant (N106A) of the human CysLT(1)R and the wild-type (WT) receptor coexpressed with the G(alphaq) subunit of the trimeric G protein, we were able to address this issue with ligands commonly used in therapy. We demonstrated that some of these molecules are inverse agonists, whereas others act as partial agonists. In cells expressing the CysLT(1)R mutant N106A exposed to Montelukast, Zafirlukast, or 3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid (MK571), the basal inositol phosphate production was reduced by 53 +/- 6, 44 +/- 3, and 54 +/- 4%, respectively. On the other hand, 6(R)-(4-carboxyphenylthio)-5(S)-hydroxy-7(E),9(E),11(Z),14(Z)-eicosatetraenoic acid (BayU9773) and 1-[2-hydroxy-3-propyl-4-[4-(1H-tetrazole-5-YL)-butoxy]-phenyl ethanone] (LY171883) acted as partial agonists and alpha-pentyl-3-[2-quinolinylmethoxy] benzyl alcohol (REV 5901) as a neutral antagonist. However, in cells expressing CysLT(1)R and G(alphaq), all antagonists used had inverse agonist activity. The decrease in basal inositol phosphate production by ligands with inverse agonist activity could be inhibited by a more neutral antagonist, confirming the specificity of the reaction. We demonstrate here that Montelukast, MK571, and Zafirlukast can act as inverse agonists on the human CysLT(1) receptor. PMID:14718577

  4. Recovery of brain biomarkers following peroxisome proliferator-activated receptor agonist neuroprotective treatment before ischemic stroke

    PubMed Central

    2014-01-01

    Background Lipid lowering agent such as agonists of peroxisome proliferator-activated receptors (PPAR) are suggested as neuroprotective agents and may protect from the sequelae of brain ischemic stroke. Although the demonstration is not clearly established in human, the underlying molecular mechanism may be of interest for future therapeutic purposes. To this end, we have used our well established rodent model of ischemia-reperfusion pre-treated or not with fenofibrate or atorvastatin and performed a differential proteomics analyses of the brain and analysed the protein markers which levels returned to “normal” following pre-treatments with PPARα agonists. Results In order to identify potential therapeutic targets positively modulated by pre-treatment with the PPARα agonists, two-dimensional gel electrophoresis proteome profiles between control, ischemia-reperfusion and pre-treated or not, were compared. The polypeptide which expression was altered following ischemia – reperfusion but whose levels remain unchanged after pre-treatment were characterized by mass spectrometry and further investigated by Western-blotting and immunohistochemistry. A series of 28 polypeptides were characterized among which the protein disulfide isomerase reduction – a protein instrumental to the unfolded protein response system - was shown to be reduced following PPARα agonists treatment while it was strongly increased in ischemia-reperfusion. Conclusions Pre-treatment with PPARα agonist or atorvastatin show potential neuroprotective effects by inhibiting the PDI overexpression in conjunction with the preservation of other neuronal markers, several of which are associated with the regulation of protein homeostasis, signal transduction and maintenance of synaptic plasticity. This proteomic study therefore suggests that neuroprotective effect of PPARα agonists supposes the preservation of the expression of several proteins essential for the maintenance of protein homeostasis not necessarily directly linked to PPARα known-regulated targets. PMID:24944524

  5. Mechanisms of action of proteinase-activated receptor agonists on human platelets

    PubMed Central

    Chung, Ada W Y; Jurasz, Paul; Hollenberg, Morley D; Radomski, Marek W

    2002-01-01

    We studied the activation of human platelets by thrombin and proteinase activated receptor (PAR)-activating peptides (PAR-APs) [SFLLRNPNDKYEPF-amide (TRAP), TFLLR-amide (PAR1AP) and AYPGKF-amide (PAR4AP)]. PAR agonist-induced platelet aggregation, glycoprotein (GP) Ib and GPIIb/IIIa surface expression and ADP release were measured by light aggregometry, flow cytometry and chemiluminescence. Aggregation inhibitors, including prostacyclin (PGI2), nitric oxide-releasing agent (S-nitroso-glutathione, GSNO), aspirin, apyrase, and phenanthroline were used to study the susceptibility of PAR agonist-induced aggregation to pharmacological inhibition. Thrombin was the most potent platelet agonist, followed by PAR1AP, TRAP and PAR4AP. The aggregatory potencies of PAR-APs were not modified by the aminopeptidase inhibitor, amastatin. Subthreshold concentrations of PAR1AP potentiated the effects of PAR4AP to stimulate maximal aggregation. Both PGI2 and GSNO reduced PAR agonist-induced aggregation and diminished GPIIb/IIIa up-regulation. PAR agonist-induced aggregation was aspirin-insensitive indicating a minor role for TXA2. In contrast, phenanthroline and apyrase significantly enhanced the anti-aggregatory effects of aspirin against thrombin-, PAR1AP- and TRAP-induced aggregation suggesting the involvement of ADP- and MMP-2-dependent pathways. PAR4AP-induced aggregation (but not PAR1AP-induced aggregation) was entirely ADP-dependent (abolished by apyrase) and resistant to phenanthroline (MMP-2-independent). Thus, the mechanisms of PAR1 and 4-induced platelet aggregation are distinct and depend differentially on their ability to interact with pathways of aggregation, along with the subsequent activation of GPIIb/IIIa receptors. PMID:11877318

  6. Structural basis for the improved potency of peroxisome proliferator-activated receptor (PPAR) agonists.

    PubMed

    Peng, Yi-Hui; Coumar, Mohane Selvaraj; Leou, Jiun-Shyang; Wu, Jian-Sung; Shiao, Hui-Yi; Lin, Chia-Hui; Lin, Wen-Hsing; Lien, Tzu Wen; Chen, Xin; Hsu, John T-A; Chao, Yu-Sheng; Huang, Chien-Fu; Lyu, Ping-Chiang; Hsieh, Hsing-Pang; Wu, Su-Ying

    2010-10-01

    The need to develop safer and more effective antidiabetic drugs is essential owing to the growth worldwide of the diabetic population. Targeting the PPAR receptor is one strategy for the treatment of diabetes; the PPAR agonists rosiglitazone and pioglitazone are already on the market. Here we report the identification of a potent PPAR agonist, 15, whose PPARγ activation was more than 20 times better than that of rosiglitazone. Compound 15 was designed to incorporate an indole head with a carboxylic acid group, and 4-phenylbenzophenone tail to achieve a PPARγ EC(50) of 10 nM. Compound 15 showed the most potent PPARγ agonist activity among the compounds we investigated. To gain molecular insight into the improved potency of 15, a structural biology study and binding energy calculations were carried out. Superimposition of the X-ray structures of 15 and agonist 10 revealed that, even though they have the same indole head part, they adopt different conformations. The head part of 15 showed stronger interactions toward PPARγ; this could be due to the presence of the novel tail part 4-phenylbenzophenone, which could enhance the binding efficiency of 15 to PPARγ. PMID:20734309

  7. Recent Updates on Peroxisome Proliferator-Activated Receptor δ Agonists for the Treatment of Metabolic Syndrome.

    PubMed

    Grewal, Ajmer S; Beniwal, Meenu; Pandita, Deepti; Sekhon, Bhupinder S; Lather, Viney

    2016-01-01

    Metabolic syndrome is a disorder described by reduced insulin sensitivity, overweight, hyperlipidaemia, high blood pressure and myocardial disorders, mainly due to high fat diet and lack of physical activity. The peroxisome proliferator activated receptors (PPARs) are type II nuclear hormone receptors that regulate a number of processes in living systems, such as metabolism of carbohydrates and fatty acids, growth and differentiation of cell, and inflammatory reactions. Alpha, gamma and delta are the three distinct isoforms of PPAR. The stimulation of PPARδ alters body's energy fuel preference from glucose to fat. The PPARδ isoform is expressed ubiquitously in all tissues, especially in those tissues which involved in metabolism of lipids like adipose tissue, liver, kidney, and muscle. Currently, PPARδ is an emerging therapeutic target for the pharmacological therapy of disorders associated with metabolic syndrome. Several PPARδ selective agonists had been reported in last ten years, many of them had been advanced into the late phase of clinical trials such as Endurobol (GW501516). However, no PPARδ agonists are yet approved for human use. The present work had been planned to cover wide variety of PPARδ agonists reported till now along with their potential role to tackle various metabolic disorders. The present review has been planned to focus mainly the most popular PPARδ agonists. PMID:26004782

  8. In vitro study on the agonistic and antagonistic activities of bisphenol-S and other bisphenol-A congeners and derivatives via nuclear receptors

    SciTech Connect

    Molina-Molina, José-Manuel; Amaya, Esperanza; Grimaldi, Marina; Sáenz, José-María; Real, Macarena; Fernández, Mariana F.; Balaguer, Patrick; Olea, Nicolás

    2013-10-01

    Bisphenols are a group of chemicals structurally similar to bisphenol-A (BPA) in current use as the primary raw material in the production of polycarbonate and epoxy resins. Some bisphenols are intended to replace BPA in several industrial applications. This is the case of bisphenol-S (BPS), which has an excellent stability at high temperature and resistance to sunlight. Studies on the endocrine properties of BPS have focused on its interaction with human estrogen receptor alpha (hERα), but information on its interaction with other nuclear receptors is scarce. The aim of this study was to investigate interactions of BPS, BPF, BPA and its halogenated derivatives, tetrachlorobisphenol A (TCBPA), and tetrabromobisphenol A (TBBPA), with human estrogen receptors (hERα and hERβ), androgen receptor (hAR), and pregnane X receptor (hPXR), using a panel of in vitro bioassays based on competitive binding to nuclear receptors (NRs), reporter gene expression, and cell proliferation assessment. BPS, BPF, and BPA efficiently activated both ERs, while TCBPA behaved as weak hERα agonist. Unlike BPF and BPA, BPS was more active in the hERβ versus hERα assay. BPF and BPA were full hAR antagonists (BPA > BPF), whereas BPA and BPS were weak hAR agonists. Only BPA, TCBPA, and TBBPA, were hPXR agonists (TCBPA > TBBPA > BPA). These findings provide evidence that BPA congeners and derivatives disrupt multiple NRs and may therefore interfere with the endocrine system. Hence, further research is needed to evaluate the potential endocrine-disrupting activity of putative BPA substitutes. - Highlights: • We investigated the agonist/antagonist activities of BPS, BPF, BPA, TCBPA and TBBPA. • The direct interaction of these compounds with hERα, hERβ, hAR and hPXR was studied. • BPA congeners and derivatives were found to disrupt multiple NRs. • Further evaluation of their role as endocrine-disrupting chemicals is needed.

  9. Marked behavioral activation from inhibitory stimulation of locus coeruleus α1-adrenoceptors by a full agonist

    PubMed Central

    Stone, Eric A.; Lin, Yan; Sarfraz, Yasmeen; Quartermain, David

    2009-01-01

    α1-Adrenoceptors are concentrated in the locus coeruleus (LC) where they appear to regulate various active behaviors but have been difficult to stimulate effectively. The present study examined the behavioral, pharmacological and neural effects of possible stimulation of these receptors with 6-fluoronorepinephrine (6FNE), the only known selective α-agonist that has full efficacy at all brain α-receptors. Infusion of this compound in the mouse LC was found to produce extreme activation of diverse motivated behaviors of exploration, wheel running and operant approach responding in different environments consistent with a global behavioral function of the dorsal noradrenergic system. Infusion of selective antagonists of α1- (terazosin) or α2-(atipamezole) receptors or of either the partial α1-agonist, phenylephrine, or full α2-agonist, dexmedetomidine, indicated that the behavioral effects of 6FNE were due largely due to activation of LC α1-receptors consistent with the known greater density of α1-than α2-adrenoreceptors in the mouse nucleus. Immunohistochemistry of fos in tyrosine hydroxylase-positive LC neurons following IV ventricular infusions indicated that 6FNE markedly depressed whereas terazosin strongly enhanced the apparent functional activity of the nucleus. The changes in fos expression following 6FNE and terazosin were significantly greater than those following dexmedetomidine and atipamezole. It is hypothesized that the α1-receptors of the mouse LC are strongly activated by 6FNE and serve to potently inhibit its tonic or stress-induced activity which in turn disinhibits prepotent motivated behaviors. PMID:19632210

  10. Zinc is a transmembrane agonist that induces platelet activation in a tyrosine phosphorylation-dependent manner.

    PubMed

    Watson, Ben R; White, Nathan A; Taylor, Kirk A; Howes, Joanna-Marie; Malcor, Jean-Daniel M; Bihan, Dominique; Sage, Stewart O; Farndale, Richard W; Pugh, Nicholas

    2016-01-20

    Following platelet adhesion and primary activation at sites of vascular injury, secondary platelet activation is induced by soluble platelet agonists, such as ADP, ATP, thrombin and thromboxane. Zinc ions are also released from platelets and damaged cells and have been shown to act as a platelet agonist. However, the mechanism of zinc-induced platelet activation is not well understood. Here we show that exogenous zinc gains access to the platelet cytosol and induces full platelet aggregation that is dependent on platelet protein tyrosine phosphorylation, PKC and integrin αIIbβ3 activity and is mediated by granule release and secondary signalling. ZnSO4 increased the binding affinity of GpVI, but not integrin α2β1. Low concentrations of ZnSO4 potentiated platelet aggregation by collagen-related peptide (CRP-XL), thrombin and adrenaline. Chelation of intracellular zinc reduced platelet aggregation induced by a number of different agonists, inhibited zinc-induced tyrosine phosphorylation and inhibited platelet activation in whole blood under physiologically relevant flow conditions. Our data are consistent with a transmembrane signalling role for zinc in platelet activation during thrombus formation. PMID:26434726

  11. Pharmacophore elucidation of phosphoiodyn A - Potent and selective peroxisome proliferator-activated receptor β/δ agonists with neuroprotective activity.

    PubMed

    Kinarivala, Nihar; Suh, Ji Ho; Botros, Mina; Webb, Paul; Trippier, Paul C

    2016-04-15

    We report the pharmacophore of the peroxisome proliferator-activated receptor δ (PPARδ) agonist natural product phosphoiodyn A is the phosphonate core. Synthesis of simplified phosphonate esters 13 and 15 provide structurally novel, highly selective and potent PPARδ agonists (EC50=78 and 112nM, respectively). Further, both compounds demonstrate significant neuroprotective activity in an in vitro cellular model indicating that phosphonates may be an effective novel scaffold for the design of therapeutics for the treatment of neurodegenerative disorders. PMID:26988304

  12. Peroxisome proliferator-activated receptor agonists modulate neuropathic pain: a link to chemokines?

    PubMed Central

    Freitag, Caroline M.; Miller, Richard J.

    2014-01-01

    Chronic pain presents a widespread and intractable medical problem. While numerous pharmaceuticals are used to treat chronic pain, drugs that are safe for extended use and highly effective at treating the most severe pain do not yet exist. Chronic pain resulting from nervous system injury (neuropathic pain) is common in conditions ranging from multiple sclerosis to HIV-1 infection to type II diabetes. Inflammation caused by neuropathy is believed to contribute to the generation and maintenance of neuropathic pain. Chemokines are key inflammatory mediators, several of which (MCP-1, RANTES, MIP-1α, fractalkine, SDF-1 among others) have been linked to chronic, neuropathic pain in both human conditions and animal models. The important roles chemokines play in inflammation and pain make them an attractive therapeutic target. Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear receptors known for their roles in metabolism. Recent research has revealed that PPARs also play a role in inflammatory gene repression. PPAR agonists have wide-ranging effects including inhibition of chemokine expression and pain behavior reduction in animal models. Experimental evidence suggests a connection between the pain ameliorating effects of PPAR agonists and suppression of inflammatory gene expression, including chemokines. In early clinical research, one PPARα agonist, palmitoylethanolamide (PEA), shows promise in relieving chronic pain. If this link can be better established, PPAR agonists may represent a new drug therapy for neuropathic pain. PMID:25191225

  13. Agonist-induced activation of rat mesenteric resistance vessels: comparison between noradrenaline and vasopressin

    SciTech Connect

    Cauvin, C.; Weir, S.W.; Wallnoefer, A.R.; Rueegg, U.P.

    1988-01-01

    The effects of noradrenaline (NA, 10(-5) M) and (arginine8)vasopressin (AVP, 10(-7) M) on tension in Ca2+-free medium and on membrane potential, and the inhibition of NA- and AVP-induced contractions by isradipine, have been compared in mesenteric resistance vessels (MRVs) from Wistar-Kyoto (WKY) rats. The release of intracellular Ca2+ by AVP contributed significantly less to its tension development than does that by NA. Nonetheless, the concentration-response curves for inhibition by isradipine of NA- and AVP-induced tonic tension were nearly identical. Similarly, these two agonists produced the same degree of membrane depolarization. In addition, both agonists were able to stimulate large contractions in vessels previously depolarized by 80 mM K+. AVP also stimulated /sup 45/Ca influx into rat cultured aortic smooth muscle cells. In contrast to the stimulation of /sup 45/Ca influx by KCl depolarization, the agonist-stimulated /sup 45/Ca influx was insensitive to inhibition by organic Ca2+ antagonists. It is concluded that Ca2+ entry through receptor-operated Ca2+-permeable channels (ROCs) may contribute to agonist-induced activation of rat aortic and MRV smooth muscle.

  14. Activation of phosphatidylinositol 4,5-bisphosphate supply by agonists and non-hydrolysable GTP analogues.

    PubMed Central

    Stephens, L; Jackson, T R; Hawkins, P T

    1993-01-01

    PtdIns(4,5)P2 serves as a precursor of a diverse family of signalling molecules, including diacylglycerol (and hence phosphatidic acid), Ins(1,4,5)P3 [and hence Ins(1,3,4,5)P4] and PtdIns(3,4,5)P3. The production of these messengers can be activated by agonists, and therefore the rate of utilization of PtdIns(4,5)P2 can vary dramatically. Although cells can only meet these large changes in demand for PtdIns(4,5)P2 by increasing its synthesis and/or by continuously cycling it at a rate that exceeds its potential consumption (avoiding the need for a co-ordinated activation mechanism), no satisfactory explanation for how this is achieved in agonist-stimulated cells has yet been provided. We show here that, in streptolysin-O-permeabilized neutrophils, N-formylmethionyl-leucyl-phenylalanine (FMLP), platelet-activating factor (PAF) and non-hydrolysable GTP analogues can cause large activations of PtdIns4P 5-kinase, suggesting that cells can accommodate agonist-activated rates of consumption of PtdIns(4,5)P2 without having to sustain continuous, comparably rapid and energetically expensive 'futile cycling' reactions. PMID:8257441

  15. Weakly sheared active suspensions: hydrodynamics, stability, and rheology.

    PubMed

    Cui, Zhenlu

    2011-03-01

    We present a kinetic model for flowing active suspensions and analyze the behavior of a suspension subjected to a weak steady shear. Asymptotic solutions are sought in Deborah number expansions. At the leading order, we explore the steady states and perform their stability analysis. We predict the rheology of active systems including an activity thickening or thinning behavior of the apparent viscosity and a negative apparent viscosity depending on the particle type, flow alignment, and the anchoring conditions, which can be tested on bacterial suspensions. We find remarkable dualities that show that flow-aligning rodlike contractile (extensile) particles are dynamically and rheologically equivalent to flow-aligning discoid extensile (contractile) particles for both tangential and homeotropic anchoring conditions. Another key prediction of this work is the role of the concentration of active suspensions in controlling the rheological behavior: the apparent viscosity may decrease with the increase of the concentration. PMID:21517529

  16. Differential activation of catalase expression and activity by PPAR agonists: implications for astrocyte protection in anti-glioma therapy.

    PubMed

    Khoo, Nicholas K H; Hebbar, Sachin; Zhao, Weiling; Moore, Steven A; Domann, Frederick E; Robbins, Mike E

    2013-01-01

    Glioma survival is dismal, in part, due to an imbalance in antioxidant expression and activity. Peroxisome proliferator-activated receptor (PPAR) agonists have antineoplastic properties which present new redox-dependent targets for glioma anticancer therapies. Herein, we demonstrate that treatment of primary cultures of normal rat astrocytes with PPAR agonists increased the expression of catalase mRNA protein, and enzymatic activity. In contrast, these same agonists had no effect on catalase expression and activity in malignant rat glioma cells. The increase in steady-state catalase mRNA observed in normal rat astrocytes was due, in part, to de novo mRNA synthesis as opposed to increased catalase mRNA stability. Moreover, pioglitazone-mediated induction of catalase activity in normal rat astrocytes was completely blocked by transfection with a PPAR?-dominant negative plasmid. These data suggest that defects in PPAR-mediated signaling and gene expression may represent a block to normal catalase expression and induction in malignant glioma. The ability of PPAR agonists to differentially increase catalase expression and activity in normal astrocytes but not glioma cells suggests that these compounds might represent novel adjuvant therapeutic agents for the treatment of gliomas. PMID:24024139

  17. Differential activation of catalase expression and activity by PPAR agonists: Implications for astrocyte protection in anti-glioma therapy?

    PubMed Central

    Khoo, Nicholas K.H.; Hebbar, Sachin; Zhao, Weiling; Moore, Steven A.; Domann, Frederick E.; Robbins, Mike E.

    2013-01-01

    Glioma survival is dismal, in part, due to an imbalance in antioxidant expression and activity. Peroxisome proliferator-activated receptor (PPAR) agonists have antineoplastic properties which present new redox-dependent targets for glioma anticancer therapies. Herein, we demonstrate that treatment of primary cultures of normal rat astrocytes with PPAR agonists increased the expression of catalase mRNA protein, and enzymatic activity. In contrast, these same agonists had no effect on catalase expression and activity in malignant rat glioma cells. The increase in steady-state catalase mRNA observed in normal rat astrocytes was due, in part, to de novo mRNA synthesis as opposed to increased catalase mRNA stability. Moreover, pioglitazone-mediated induction of catalase activity in normal rat astrocytes was completely blocked by transfection with a PPAR?-dominant negative plasmid. These data suggest that defects in PPAR-mediated signaling and gene expression may represent a block to normal catalase expression and induction in malignant glioma. The ability of PPAR agonists to differentially increase catalase expression and activity in normal astrocytes but not glioma cells suggests that these compounds might represent novel adjuvant therapeutic agents for the treatment of gliomas. PMID:24024139

  18. Collybolide is a novel biased agonist of κ-opioid receptors with potent antipruritic activity.

    PubMed

    Gupta, Achla; Gomes, Ivone; Bobeck, Erin N; Fakira, Amanda K; Massaro, Nicholas P; Sharma, Indrajeet; Cavé, Adrien; Hamm, Heidi E; Parello, Joseph; Devi, Lakshmi A

    2016-05-24

    Among the opioid receptors, the κ-opioid receptor (κOR) has been gaining considerable attention as a potential therapeutic target for the treatment of complex CNS disorders including depression, visceral pain, and cocaine addiction. With an interest in discovering novel ligands targeting κOR, we searched natural products for unusual scaffolds and identified collybolide (Colly), a nonnitrogenous sesquiterpene from the mushroom Collybia maculata. This compound has a furyl-δ-lactone core similar to that of Salvinorin A (Sal A), another natural product from the plant Salvia divinorum Characterization of the molecular pharmacological properties reveals that Colly, like Sal A, is a highly potent and selective κOR agonist. However, the two compounds differ in certain signaling and behavioral properties. Colly exhibits 10- to 50-fold higher potency in activating the mitogen-activated protein kinase pathway compared with Sal A. Taken with the fact that the two compounds are equipotent for inhibiting adenylyl cyclase activity, these results suggest that Colly behaves as a biased agonist of κOR. Behavioral studies also support the biased agonistic activity of Colly in that it exhibits ∼10-fold higher potency in blocking non-histamine-mediated itch compared with Sal A, and this difference is not seen in pain attenuation by these two compounds. These results represent a rare example of functional selectivity by two natural products that act on the same receptor. The biased agonistic activity, along with an easily modifiable structure compared with Sal A, makes Colly an ideal candidate for the development of novel therapeutics targeting κOR with reduced side effects. PMID:27162327

  19. FRET-Based Detection of M1 Muscarinic Acetylcholine Receptor Activation by Orthosteric and Allosteric Agonists

    PubMed Central

    Markovic, Danijela; Holdich, Jonathan; Al-Sabah, Suleiman; Mistry, Rajendra; Krasel, Cornelius; Mahaut-Smith, Martyn P.; Challiss, R. A. John

    2012-01-01

    Background and Objective Muscarinic acetylcholine receptors (mAChRs) are 7-transmembrane, G protein-coupled receptors that regulate a variety of physiological processes and represent potentially important targets for therapeutic intervention. mAChRs can be stimulated by full and partial orthosteric and allosteric agonists, however the relative abilities of such ligands to induce conformational changes in the receptor remain unclear. To gain further insight into the actions of mAChR agonists, we have developed a fluorescently tagged M1 mAChR that reports ligand-induced conformational changes in real-time by changes in Frster resonance energy transfer (FRET). Methods Variants of CFP and YFP were inserted into the third intracellular loop and at the end of the C-terminus of the mouse M1 mAChR, respectively. The optimized FRET receptor construct (M1-cam5) was expressed stably in HEK293 cells. Results The variant CFP/YFP-receptor chimera expressed predominantly at the plasma membrane of HEK293 cells and displayed ligand-binding affinities comparable with those of the wild-type receptor. It also retained an ability to interact with G?q/11 proteins and to stimulate phosphoinositide turnover, ERK1/2 phosphorylation and undergo agonist-dependent internalization. Addition of the full agonist methacholine caused a reversible decrease in M1 FRET (FEYFP/FECFP) that was prevented by atropine pre-addition and showed concentration-dependent amplitude and kinetics. Partial orthosteric agonists, arecoline and pilocarpine, as well as allosteric agonists, AC-42 and 77-LH-28-1, also caused atropine-sensitive decreases in the FRET signal, which were smaller in amplitude and significantly slower in onset compared to those evoked by methacholine. Conclusion The M1 FRET-based receptor chimera reports that allosteric and orthosteric agonists induce similar conformational changes in the third intracellular loop and/or C-terminus, and should prove to be a valuable molecular reagent for pharmacological and structural investigations of M1 mAChR activation. PMID:22272263

  20. In vitro activity of RO363, a beta1-adrenoceptor selective agonist.

    PubMed Central

    Iakovidis, D.; Malta, E.; McPherson, G. A.; Raper, C.

    1980-01-01

    1 The beta-adrenoceptor stimulant effects of RO363 and (--)-isoprenaline have been compared in a variety of isolated tissue preparations. 2 RO363 is approximately half as potent as (--)-isoprenaline in tissues where actions are due to beta1-receptor activation (guinea-pig atrial and ileal preparations and ventricular strips from the rabbit, rat and guinea-pig. 3 In uterine and lung strip preparations from the guinea-pig, where responses are due to beta2-receptor stimulation. RO363 is 100 to 350 times less active than (--)-isoprenaline and has a low intrinsic activity. 4 In spontaneously contracted tracheal preparations from the guinea-pig, RO363 is a full agonist and is approximately half as potent as (--)-isoprenaline. These effects of RO363 are due to the activation of a population of beta1-receptors in the tissue since RO363 and (--)-isoprenaline have the same relative potencies in trachea, cardiac and ileal preparations. In addition the Kb values for practolol are similar in all these preparations when RO363 is used as the agonist. 5 The results show that RO363 is a potent and highly selective beta1-receptor agonist. PMID:6103722

  1. E17110 promotes reverse cholesterol transport with liver X receptor β agonist activity in vitro

    PubMed Central

    Li, Ni; Wang, Xiao; Liu, Peng; Lu, Duo; Jiang, Wei; Xu, Yanni; Si, Shuyi

    2016-01-01

    Liver X receptor (LXR) plays an important role in reverse cholesterol transport (RCT), and activation of LXR could reduce atherosclerosis. In the present study we used a cell-based screening method to identify new potential LXRβ agonists. A novel benzofuran-2-carboxylate derivative was identified with LXRβ agonist activity: E17110 showed a significant activation effect on LXRβ with an EC50 value of 0.72 μmol/L. E17110 also increased the expression of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1) in RAW264.7 macrophages. Moreover, E17110 significantly reduced cellular lipid accumulation and promoted cholesterol efflux in RAW264.7 macrophages. Interestingly, we found that the key amino acids in the LXRβ ligand-binding domain had distinct interactions with E17110 as compared to TO901317. These results suggest that E17110 was identified as a novel compound with LXRβ agonist activity in vitro via screening, and could be developed as a potential anti-atherosclerotic lead compound. PMID:27175330

  2. Less precise motor control leads to increased agonist-antagonist muscle activation during stick balancing.

    PubMed

    Reeves, N Peter; Popovich, John M; Vijayanagar, Vilok; Pathak, Pramod K

    2016-06-01

    Human motor control has constraints in terms of its responsiveness, which limit its ability to successfully perform tasks. In a previous study, it was shown that the ability to balance an upright stick became progressively more challenging as the natural frequency (angular velocity without control) of the stick increased. Furthermore, forearm and trunk agonist and antagonist muscle activation increased as the natural frequency of the stick increased, providing evidence that the central nervous system produces agonist-antagonist muscle activation to match task dynamics. In the present study, visual feedback of the stick position was influenced by changing where subject focused on the stick during stick balancing. It was hypothesized that a lower focal height would degrade motor control (more uncertainty in tracking stick position), thus making balancing more challenging. The probability of successfully balancing the stick at four different focal heights was determined along with the average angular velocity of the stick. Electromyographic signals from forearm and trunk muscles were also recorded. As expected, the probability of successfully balancing the stick decreased and the average angular velocity of the stick increased as subjects focused lower on the stick. In addition, changes in the level of agonist and antagonist muscle activation in the forearm and trunk was linearly related to changes in the angular velocity of the stick during balancing. One possible explanation for this is that the central nervous system increases muscle activation to account for less precise motor control, possibly to improve the responsiveness of human motor control. PMID:27010497

  3. Activation of Human Brown Adipose Tissue by a β3-Adrenergic Receptor Agonist

    PubMed Central

    Cypess, Aaron M.; Weiner, Lauren S.; Roberts-Toler, Carla; Elía, Elisa Franquet; Kessler, Skyler H.; Kahn, Peter A.; English, Jeffrey; Chatman, Kelly; Trauger, Sunia A.; Doria, Alessandro; Kolodny, Gerald M.

    2015-01-01

    SUMMARY Increasing energy expenditure through activation of endogenous brown adipose tissue (BAT) is a potential approach to treat obesity and diabetes. The class of β3-adrenergic receptor (AR) agonists stimulates rodent BAT, but this activity has never been demonstrated in humans. Here we determined the ability of 200 mg oral mirabegron (Myrbetriq, Astellas Pharma, Inc.), a β3-AR agonist currently approved to treat overactive bladder, to stimulate BAT as compared to placebo. Mirabegron led to higher BAT metabolic activity as measured via 18F-fluorodeoxyglucose (18F-FDG) using positron emission tomography (PET) combined with computed tomography (CT) in all twelve healthy male subjects (p = 0.001), and it increased resting metabolic rate (RMR) by 203 ± 40 kcal/day (+13%; p = 0.001). BAT metabolic activity was also a significant predictor of the changes in RMR (p = 0.006). Therefore, a β3-AR agonist can stimulate human BAT thermogenesis and may be a promising treatment for metabolic disease. PMID:25565203

  4. Synthesis and activity of 4,5-diarylimidazoles as human CB1 receptor inverse agonists.

    PubMed

    Plummer, Christopher W; Finke, Paul E; Mills, Sander G; Wang, Junying; Tong, Xinchun; Doss, George A; Fong, Tung M; Lao, Julie Z; Schaeffer, Marie-Therese; Chen, Jing; Shen, Chun-Pyn; Stribling, D Sloan; Shearman, Lauren P; Strack, Alison M; Van der Ploeg, Lex H T

    2005-03-01

    Structure-activity relationship studies directed toward the optimization of 4,5-diarylimidazole-2-carboxamide analogs as human CB1 receptor inverse agonists resulted in the discovery of the two amide derivatives 24a and b (hCB1 IC50 = 6.1 and 4.0 nM) which also demonstrated efficacy in overnight feeding studies in the rat for reduction in both food intake and overall body weight. PMID:15713403

  5. A Light-Controlled TLR4 Agonist and Selectable Activation of Cell Subpopulations.

    PubMed

    Stutts, Lalisa; Esser-Kahn, Aaron P

    2015-08-17

    The spatial and temporal aspects of immune cell signaling are key parameters in defining the magnitude of an immune response. Toll-like receptors (TLRs) on innate immune cells are important in the early detection of pathogens and initiation of an immune response. Controlling the spatial and temporal signaling of TLRs would enable further study of immune synergies and assist in the development of new vaccines. Here, we show a light-based method for the spatial control of TLR4 signaling. A TLR4 agonist, pyrimido[5,4-b]indole, was protected with a cage at a position critical for receptor binding. This afforded a photocontrollable agonist that was inactive while caged, yet effected NF-?B activity in cells following UV photocontrolled deprotection. We demonstrated spatial control of NF-?B activation within a population of cells by treating all cells with the caged TLR4 agonist and constraining light exposure and consequent activation to a region of interest. PMID:26097006

  6. Agonists and protein kinase C-activation induce phosphorylation and internalization of FFA1 receptors.

    PubMed

    Sosa-Alvarado, Carla; Hernández-Méndez, Aurelio; Romero-Ávila, M Teresa; Sánchez-Reyes, Omar B; Takei, Yoshinori; Tsujimoto, Gozoh; Hirasawa, Akira; García-Sáinz, J Adolfo

    2015-12-01

    FFA1 (previously known as GPR40) is a free fatty acid receptor involved in the regulation of inflammatory processes and insulin secretion. The cellular actions resulting from FFA1 activation have received considerable attention. However, little is known on the regulation of the receptor function. In the present work, using cells transfected with this receptor, docosahexaenoic acid and α-linolenic acid increased intracellular calcium concentration and ERK 1/2 phosphorylation. It was also observed that FFA1 is a phosphoprotein whose phosphorylation state was increased (2- to 3-fold) by agonists (i.e., free fatty acids) and also by phorbol myristate acetate. Agonist- and phorbol ester-mediated FFA1 phosphorylation was markedly reduced by inhibitors of protein kinase C. Receptor stimulation by free fatty acids and protein kinase C activation also induced receptor internalization as evidenced by confocal microscopy. In summary, our data show that FFA1 is a phosphoprotein whose phosphorylation state is modulated by agonists and protein kinase C activation; such covalent modification is associated with receptor internalization. PMID:26526350

  7. Did Weak-line Quasars Just Begin an Active Phase?

    NASA Astrophysics Data System (ADS)

    Plotkin, Richard M.; Anderson, S. F.; Brandt, W. N.; Diamond-Stanic, A. M.; Fan, X.; MacLeod, C. L.; Markoff, S.; Schneider, D. P.; Shemmer, O.

    2011-01-01

    Active Galactic Nuclei (AGN) are often defined by their prominent emission lines, and rare instances of AGN lacking strong emission features are often explained by the presence of a relativistically boosted radio jet (i.e., as for BL Lac objects). However, the SDSS has discovered a population of 80 high-redshift (z>2.2) radio-quiet quasars with weak emission lines (WLQs) not predicted by the standard orientation based model. Inclusive AGN selection approaches are now also revealing lower-redshift radio-quiet AGN lacking strong emission lines (around 100 objects to date), which are potential analogs to WLQs. Here, we describe our sample of low-redshift WLQ candidates, and we present follow-up multiwavelength observations for 26 objects. Our conclusion is WLQs likely have intrinsically weak broad emission line regions. Finally, we compare WLQs to accreting stellar mass black holes to explore the possibility that WLQs are in a short-lived evolutionary stage where quasar activity has only recently begun. Studying extreme examples of AGN like WLQs may lead to new insight into the formation of broad emission line regions in AGN. Support for this work was provided by a Netherlands Organization for Scientific Research (NWO) Vidi Fellowship.

  8. Highly Selective Salicylketoxime-Based Estrogen Receptor β Agonists Display Antiproliferative Activities in a Glioma Model

    PubMed Central

    2016-01-01

    Estrogen receptor β (ERβ) selective agonists are considered potential therapeutic agents for a variety of pathological conditions, including several types of cancer. Their development is particularly challenging, since differences in the ligand binding cavities of the two ER subtypes α and β are minimal. We have carried out a rational design of new salicylketoxime derivatives which display unprecedentedly high levels of ERβ selectivity for this class of compounds, both in binding affinity and in cell-based functional assays. An endogenous gene expression assay was used to further characterize the pharmacological action of these compounds. Finally, these ERβ-selective agonists were found to inhibit proliferation of a glioma cell line in vitro. Most importantly, one of these compounds also proved to be active in an in vivo xenograft model of human glioma, thus demonstrating the high potential of this type of compounds against this devastating disease. PMID:25559213

  9. Peroxisome proliferator-activated receptors (PPARs) and PPAR agonists: the 'future' in dermatology therapeutics?

    PubMed

    Gupta, Mrinal; Mahajan, Vikram K; Mehta, Karaninder S; Chauhan, Pushpinder S; Rawat, Ritu

    2015-11-01

    Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors and comprise three different isoforms namely PPARα, PPARγ, and PPARβ/δ with PPARβ/δ being the predominant subtype in human keratinocytes. After binding with specific ligands, PPARs regulate gene expression, cell growth and differentiation, apoptosis, inflammatory responses, and tumorogenesis. PPARs also modulate a wide variety of skin functions including keratinocyte proliferation, epidermal barrier formation, wound healing, melanocyte proliferation, and sebum production. Recent studies have shown the importance of PPARs in the pathogenesis of many dermatological disorders. Clinical trials have suggested possible role of PPAR agonists in the management of various dermatoses ranging from acne vulgaris, psoriasis, hirsutism, and lipodystrophy to cutaneous malignancies including melanoma. This article is intended to be a primer for dermatologists in their understanding of clinical relevance of PPARs and PPAR agonists in dermatology therapeutics. PMID:25986745

  10. AGONISTIC ENCOUNTERS AND BRAIN ACTIVATION IN DOMINANT AND SUBORDINATE MALE GREATER LONG-TAILED HAMSTERS

    PubMed Central

    Pan, Yongliang; Xu, Linxi; Young, Kimberly A.; Wang, Zuoxin; Zhang, Zhibin

    2010-01-01

    During an agonistic encounter test, dominant male greater long-tailed hamsters (Tscheskia triton) initiated attacks sooner and displayed higher levels of aggression and flank marking behavior than their subordinate counterparts. Accordingly, subordinate males exhibited more defensive behavior than dominant ones. Specific patterns of neuronal activation, measured by Fos-immunoreactive staining (Fos-ir), were found in the hamster brain following agonistic interactions. Increased Fos-ir was observed in the bed nucleus of the stria terminalis (BST), ventromedial hypothalamus (VMH), and medial (MeA) and anterior cortical (ACo) nuclei of the amygdala (AMYG) in both dominant and subordinate males. In contrast, dominant males had significantly higher Fos-ir densities in the medial preoptic area (MPOA) than subordinate males, whereas subordinate males expressed higher densities of Fos-ir in the anterior hypothalamus (AH) and central nucleus of the amygdala (CeA). Additionally, Fos-ir levels in the MPOA were significantly correlated with aggression and Fos-ir levels in the AH and CeA were correlated with defensive behavior. Together, our data indicate distinct patterns of neuronal activation associated with agonistic encounters in a behavior-specific manner in male greater long-tailed hamsters. PMID:20471386

  11. β-Agonist-induced constitutive β2-adrenergic receptor activity in bovine tracheal smooth muscle

    PubMed Central

    de Vries, Berber; Meurs, Herman; Roffel, Ad F; Elzinga, Carolina R S; Hoiting, Ben H; de Vries, Marleen M L; Zaagsma, Johan

    2000-01-01

    According to the two state receptor model, the β2-adrenergic receptor (β2-AR) isomerizes between an inactive state and a constitutively active state, which couples to the stimulatory G-protein in the absence of agonist. In bovine tracheal smooth muscle (BTSM), we investigated the effect of short and long term β2-AR activation by fenoterol on constitutive receptor activity. Preincubation of the BTSM strips for 5 min, 30 min and 18 h with 10 μM fenoterol, followed by extensive washout (3 h, 37°C), caused a rapid and time-dependent inhibition of KCl-induced contraction, reaching 68±10, 51±6 and 46±4% of control, respectively, at 40 mM KCl (P<0.05 all). At all time points, the EC50 values to KCl were significantly reduced as well. Preincubation of BTSM with 0.1, 1.0 and 10 μM fenoterol during 18 h caused a concentration-dependent decrease of the 40 mM KCl response to 70±5, 47±12 and 43±9% of control, respectively (P<0.05 all). The reduced KCl contractions were reversed in the presence of 1 μM timolol. Moreover, the sensitivity to KCl in the presence of timolol was enhanced after fenoterol incubation. Inverse agonism was also found for other β-blockers, with a rank order of efficacy of pindolol ⩾timolol=propranolol>alprenolol⩾sotalol>labetalol. At 25 mM KCl-induced tone, the contraction induced by cumulative timolol administration was competitively antagonized by the less efficacious inverse agonist labetalol, indicating that the fenoterol-induced effects cannot be explained by residual β-agonist binding. In conclusion, fenoterol treatment of BTSM causes a time- and concentration-dependent development of constitutive β2-AR activity, which can be reversed by various inverse agonists. The β-agonist-induced changes could represent a novel regulation mechanism of β2-AR activity. PMID:11053211

  12. Discovery of the oxazabicyclo[3.3.1]nonane derivatives as potent and orally active GPR119 agonists.

    PubMed

    Dai, Xing; Stamford, Andrew; Liu, Hong; Neustadt, Bernard; Hao, Jingsong; Kowalski, Tim; Hawes, Brian; Xu, Xiaoying; Baker, Hana; O'Neill, Kim; Woods, Morgan; Tang, Huadong; Greenlee, William

    2015-11-15

    The design and synthesis of two conformationally restricted oxazabicyclo octane derivatives as GRP119 agonists is described. Derivatives of scaffold C, with syn configuration, have the best overall profiles with respect to solubility and in vivo efficacy. Compound 25a was found to have extremely potent agonistic activity and was orally active in lowering blood glucose levels in a mouse oral glucose tolerance test at a dose of 0.1 mg/kg. PMID:26433449

  13. A potential antidepressant activity of SA4503, a selective sigma 1 receptor agonist.

    PubMed

    Skuza, G; Rogóz, Z

    2002-11-01

    The aim of the present study was to examine SA4503 [1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride], a novel selective receptor agonist, in respect of its potential antidepressant action. To this end we used a forced swimming test in rats to study SA4503 alone, as well as its interaction with imipramine, a classic tricyclic antidepressant. SA4503 decreased the immobility time in the forced swimming test in rats (although only at one of the three doses used); at the same time it did not change the locomotor activity recorded under the same experimental conditions. Moreover, SA4503 showed a synergistic effect with imipramine in the forced swimming test (both those compounds given jointly decreased the immobility time, but were ineffective when administered separately). It had previously been shown that repeated administration of antidepressants with different pharmacological profiles enhanced the action of D-amphetamine, quinpirole and other dopamine stimulants. SA4503 administered repeatedly increased the locomotor hyperactivity induced by D-amphetamine and quinpirole (a dopamine D /D receptor agonist), but not by (+/-)-7-hydroxy-dipropyloamino-tetralin hydrobromide [(+/-)-7-OH-DPAT; a dopamine D receptor agonist]. The results presented in this paper support the suggestion that SA4503 may have potential antidepressive properties. PMID:12409992

  14. Airway peroxidases catalyze nitration of the {beta}2-agonist salbutamol and decrease its pharmacological activity.

    PubMed

    Reszka, Krzysztof J; Sallans, Larry; Macha, Stephen; Brown, Kari; McGraw, Dennis W; Kovacic, Melinda Butsch; Britigan, Bradley E

    2011-02-01

    β(2)-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 β(2)-agonist, is subject to potentially inactivating nitration. When salbutamol was exposed to myeloperoxidase, eosinophil peroxidase or lactoperoxidase in the presence of hydrogen peroxide (H(2)O(2)) and nitrite (NO(2)(-)), 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 pK(a) 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 β(2)-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/H(2)O(2)/NO(2)(-) being the most affected. Functionally, nitrated salbutamol showed decreased affinity for β(2)-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 β(2)-agonists may be subject to peroxidase-catalyzed nitration that could potentially diminish their therapeutic efficacy. PMID:20974700

  15. Structure-activity relationship studies toward the discovery of selective apelin receptor agonists.

    PubMed

    Margathe, Jean-Franois; Iturrioz, Xavier; Alvear-Perez, Rodrigo; Marsol, Claire; Rich, Stphanie; Chabane, Hadjila; Tounsi, Nassera; Kuhry, Maxime; Heissler, Denis; Hibert, Marcel; Llorens-Cortes, Catherine; Bonnet, Dominique

    2014-04-10

    Apelin is the endogenous ligand for the previously orphaned G protein-coupled receptor APJ. Apelin and its receptor are widely distributed in the brain, heart, and vasculature, and are emerging as an important regulator of body fluid homeostasis and cardiovascular functions. To further progress in the pharmacology and the physiological role of the apelin receptor, the development of small, bioavailable agonists and antagonists of the apelin receptor, is crucial. In this context, E339-3D6 (1) was described as the first nonpeptidic apelin receptor agonist. We show here that 1 is actually a mixture of polymethylated species, and we describe an alternative and versatile solid-phase approach that allows access to highly pure 27, the major component of 1. This approach was also applied to prepare a series of derivatives in order to identify the crucial structural determinants required for the ligand to maintain its affinity for the apelin receptor as well as its capacity to promote apelin receptor signaling and internalization. The study of the structure-activity relationships led to the identification of ligands 19, 21, and 38, which display an increased affinity compared to that of 27. The latter and 19 behave as full agonists with regard to cAMP production and apelin receptor internalization, whereas 21 is a biased agonist toward cAMP production. Interestingly, the three ligands display a much higher stability in mouse plasma (T1/2 > 10 h) than the endogenous apelin-17 peptide 2 (T1/2 < 4 min). PMID:24625069

  16. Antimicrobial activity and stability of weakly acidified chlorous acid water.

    PubMed

    Horiuchi, Isanori; Kawata, Hiroyuki; Nagao, Tamiko; Imaohji, Haruyuki; Murakami, Kazuya; Kino, Yasuhiro; Yamasaki, Hisashi; Koyama, A Hajime; Fujita, Yatsuka; Goda, Hisataka; Kuwahara, Tomomi

    2015-01-01

    The antimicrobial activity of weakly acidified chlorous acid water (WACAW) against Staphylococcus aureus, non-pathogenic Escherichia coli, enterohemorrhagic E. coli (EHEC O157:H7), Candida albicans, and spore-forming Bacillus and Paenibacillus species was evaluated in vitro. The antiviral activity was also examined using feline calicivirus (FCV). Diluted WACAW (>100 ppm) effectively reduced the number of non-spore-forming bacteria (>4 log10 CFU reductions) within 5 min. Treatment with this sanitizer at 400 ppm for 30 min achieved>5 log10 CFU reductions in spore-forming Bacillus and Paenibacillus species while an equivalent concentration of sodium hypochlorite (NaClO) resulted in only a 0.98 and 2.72 log10 CFU reduction, respectively. The effect of this sanitizer against FCV was equivalent to that of NaClO. Immersion in WACAW (400 ppm) achieved >4 and 2.26 log10 CFU reductions in Campylobacter jejuni and EHEC, respectively, on artificially contaminated broiler carcass pieces. Finally, theantimicrobial activity of this sanitizer was shown to be maintained for at least 28 d when in contact with nonwoven fabric (100% cotton). This study showed that pH control of chlorous acid is expected to modify its antimicrobial activity and stability. WACAW is expected to have applications in various settings such as the food processing and healthcare industries. PMID:25817812

  17. Assessment of a novel β2-adrenoceptor agonist, trantinterol, for interference with human liver cytochrome P450 enzymes activities.

    TOXLINE Toxicology Bibliographic Information

    Jiang K; Li K; Qin F; Lu X; Li F

    2011-08-01

    The effect of a novel β(2)-adrenoceptor agonist, trantinterol on the activities of cytochrome P450 (CYP450) was investigated with human liver microsomes and human cryohepatocytes in order to assess the potential for drug-drug interactions. The ability of trantinterol to inhibit CYP450 activities was evaluated in vitro in human liver microsomes. Trantinterol did not inhibit CYP2C19, CYP2D6, and CYP3A4/5 (IC(50)>100 μM). It acted as a weak inhibitor of CYP1A2 and CYP2C9 with IC(50) of 70.8 and 81.9 μM, respectively. No time-dependent inhibitions were observed in the present research. To evaluate CYP450 induction, human cryohepatocytes (n=3) were used and treated once daily for 3 days with trantinterol (0.01, 0.1, and 1 ng/ml), after which CYP450 activities were measured. At concentration of 0.01 ng/ml, which is close to the C(max) at maximal recommended doses (50 μg), trantinterol was about 8% as effective as omeprazole (CYP1A2 inducer) only with donor 2. At concentration of 1 ng/ml, trantinterol was about 3.6 ± 3.1% as effective as rifampin (CYP3A4/5 inducer). These in vitro results indicated that, at pharmacological relevant concentrations, trantinterol will not produce clinically significant CYP450 inhibition or induction.

  18. Structural insights for the design of new PPARgamma partial agonists with high binding affinity and low transactivation activity.

    PubMed

    Guasch, Laura; Sala, Esther; Valls, Cristina; Blay, Mayte; Mulero, Miquel; Arola, Lluís; Pujadas, Gerard; Garcia-Vallvé, Santiago

    2011-08-01

    Peroxisome Proliferator-Activated Receptor γ (PPARγ) full agonists are molecules with powerful insulin-sensitizing action that are used as antidiabetic drugs. Unfortunately, these compounds also present various side effects. Recent results suggest that effective PPARγ agonists should show a low transactivation activity but a high binding affinity to inhibit phosphorylation at Ser273. We use several structure activity relationship studies of synthetic PPARγ agonists to explore the different binding features of full and partial PPARγ agonists with the aim of differentiating the features needed for binding and those needed for the transactivation activity of PPARγ. Our results suggest that effective partial agonists should have a hydrophobic moiety and an acceptor site with an appropriate conformation to interact with arm II and establish a hydrogen bond with Ser342 or an equivalent residue at arm III. Despite the fact that interactions with arm I increase the binding affinity, this region should be avoided in order to not increase the transactivation activity of potential PPARγ partial agonists. PMID:21691811

  19. Bis(ammonio)alkane-type agonists of muscarinic acetylcholine receptors: synthesis, in vitro functional characterization, and in vivo evaluation of their analgesic activity.

    PubMed

    Matera, Carlo; Flammini, Lisa; Quadri, Marta; Vivo, Valentina; Ballabeni, Vigilio; Holzgrabe, Ulrike; Mohr, Klaus; De Amici, Marco; Barocelli, Elisabetta; Bertoni, Simona; Dallanoce, Clelia

    2014-03-21

    In this study, we synthesized and tested in vitro and in vivo two groups of bis(ammonio)alkane-type compounds, 6a-9a and 6b-9b, which incorporate the orthosteric muscarinic agonist iperoxo into a molecular fragment of the M2-selective allosteric modulators W84 and naphmethonium. The agonist potency and efficacy of these hybrid derivatives at M1, M2 and M3 muscarinic receptor subtypes and their anticholinesterase activity were evaluated on isolated tissue preparations. Their analgesic action was then assayed in vivo in the acetic acid writhing test and the occurrence of peripheral and central cholinergic side effects was also determined. The investigated hybrids behaved as potent muscarinic agonists and weak cholinesterase inhibitors. These effects were more pronounced for bisquaternary salts bearing the naphmethonium moiety than for the W84-containing analogs, and resulted in a significant analgesic activity in vivo. A promising profile was displayed by the naphmethonium-related compound 8b, which combined the most potent antinociception among the test compounds with the absence of relevant cholinergic side effects. PMID:24534538

  20. Cannabinoid agonists rearrange synaptic vesicles at excitatory synapses and depress motoneuron activity in vivo.

    PubMed

    García-Morales, Victoria; Montero, Fernando; Moreno-López, Bernardo

    2015-05-01

    Impairment of motor skills is one of the most common acute adverse effects of cannabis. Related studies have focused mainly on psychomotor alterations, and little is known about the direct impact of cannabinoids (CBs) on motoneuron physiology. As key modulators of synaptic function, CBs regulate multiple neuronal functions and behaviors. Presynaptic CB1 mediates synaptic strength depression by inhibiting neurotransmitter release, via a poorly understood mechanism. The present study examined the effect of CB agonists on excitatory synaptic inputs incoming to hypoglossal motoneurons (HMNs) in vitro and in vivo. The endocannabinoid anandamide (AEA) and the synthetic CB agonist WIN 55,212-2 rapidly and reversibly induced short-term depression (STD) of glutamatergic synapses on motoneurons by a presynaptic mechanism. Presynaptic effects were fully reversed by the CB1-selective antagonist AM281. Electrophysiological and electron microscopy analysis showed that WIN 55,212-2 reduced the number of synaptic vesicles (SVs) docked to active zones in excitatory boutons. Given that AM281 fully abolished depolarization-induced depression of excitation, motoneurons can be feasible sources of CBs, which in turn act as retrograde messengers regulating synaptic function. Finally, microiontophoretic application of the CB agonist O-2545 reversibly depressed, presumably via CB1, glutamatergic inspiratory-related activity of HMNs in vivo. Therefore, evidence support that CBs, via presynaptic CB1, induce excitatory STD by reducing the readily releasable pool of SVs at excitatory synapses, then attenuating motoneuron activity. These outcomes contribute a possible mechanistic basis for cannabis-associated motor performance disturbances such as ataxia, dysarthria and dyscoordination. PMID:25595101

  1. PPARα Agonist WY-14643 Induces SIRT1 Activity in Rat Fatty Liver Ischemia-Reperfusion Injury

    PubMed Central

    Pantazi, Eirini; Folch-Puy, Emma; Bejaoui, Mohamed; Panisello, Arnau; Varela, Ana Teresa; Rolo, Anabela Pinto; Palmeira, Carlos Marques; Roselló-Catafau, Joan

    2015-01-01

    Ischemia-reperfusion injury (IRI) remains a frequent complication in surgery, especially in case of steatotic livers that present decreased tolerance towards IRI. Apart from its major role in metabolism, activation of peroxisome proliferator-activated receptor α (PPARα) has been related with positive effects on IRI. In addition, the deacetylase enzyme sirtuin 1 (SIRT1) has recently emerged as a promising target for preventing IRI, through its interaction with stress-related mechanisms, such as endoplasmic reticulum stress (ERS). Taking this into account, this study aims to explore whether PPARα agonist WY-14643 could protect steatotic livers against IRI through sirtuins and ERS signaling pathway. Obese Zucker rats were pretreated or not pretreated with WY-14643 (10 mg/kg intravenously) and then submitted to partial (70%) hepatic ischemia (1 hour) followed by 24 hours of reperfusion. Liver injury (ALT levels), lipid peroxidation (MDA), SIRT1 activity, and the protein expression of SIRT1 and SIRT3 and ERS parameters (IRE1α, peIF2, caspase 12, and CHOP) were evaluated. Treatment with WY-14643 reduced liver injury in fatty livers, enhanced SIRT1 activity, and prevented ERS. Together, our results indicated that PPARα agonist WY-14643 may exert its protective effect in fatty livers, at least in part, via SIRT1 induction and ERS prevention. PMID:26539534

  2. Microbiome-Derived Tryptophan Metabolites and Their Aryl Hydrocarbon Receptor-Dependent Agonist and Antagonist Activities

    PubMed Central

    Jin, Un-Ho; Lee, Syng-Ook; Sridharan, Gautham; Lee, Kyongbum; Davidson, Laurie A.; Jayaraman, Arul; Chapkin, Robert S.; Alaniz, Robert

    2014-01-01

    The tryptophan metabolites indole, indole-3-acetate, and tryptamine were identified in mouse cecal extracts and fecal pellets by mass spectrometry. The aryl hydrocarbon receptor (AHR) agonist and antagonist activities of these microbiota-derived compounds were investigated in CaCo-2 intestinal cells as a model for understanding their interactions with colonic tissue, which is highly aryl hydrocarbon (Ah)–responsive. Activation of Ah-responsive genes demonstrated that tryptamine and indole 3-acetate were AHR agonists, whereas indole was an AHR antagonist that inhibited TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin)–induced CYP1A1 expression. In contrast, the tryptophan metabolites exhibited minimal anti-inflammatory activities, whereas TCDD decreased phorbol ester-induced CXCR4 [chemokine (C-X-C motif) receptor 4] gene expression, and this response was AHR dependent. These results demonstrate that the tryptophan metabolites indole, tryptamine, and indole-3-acetate modulate AHR-mediated responses in CaCo-2 cells, and concentrations of indole that exhibit AHR antagonist activity (100–250 μM) are detected in the intestinal microbiome. PMID:24563545

  3. Pindolol--a beta-adrenoceptor blocking drug with partial agonist activity: clinical pharmacological considerations.

    PubMed Central

    Aellig, W H

    1982-01-01

    1 Pindolol is a beta-adrenoceptor antagonist equally effective on beta 1- and beta 2-adrenoceptors which has a relatively long duration of action. It is practically completely absorbed and, unlike most other beta-adrenoceptor blockers, is only metabolized to a small extent during the first passage through the liver. 2 Pindolol possesses partial agonist activity (intrinsic sympathomimetic activity, ISA). This means that apart from blocking beta-adrenoceptors it produces some stimulation. Pindolol therefore only slightly influences normal sympathetic drive at rest but effectively reduces the effects of elevated sympathetic activity. 3 Various therapeutic advantages have been attributed to the partial agonist activity of pindolol: no or only slight alterations in normal cardiac output, heart rate and peripheral blood flow occur. Peripheral resistance is reduced during chronic oral therapy. No alteration of HDL/LDL cholesterol ratio has been observed. Rebound phenomena on sudden withdrawal of therapy and bronchoconstriction in susceptible patients are less likely than with drugs devoid of ISA. PMID:6125169

  4. Polyyne Hybrid Compounds from Notopterygium incisum with Peroxisome Proliferator-Activated Receptor Gamma Agonistic Effects

    PubMed Central

    2014-01-01

    In the search for peroxisome proliferator-activated receptor gamma (PPARγ) active constituents from the roots and rhizomes of Notopterygium incisum, 11 new polyacetylene derivatives (1–11) were isolated. Their structures were elucidated by NMR and HRESIMS as new polyyne hybrid molecules of falcarindiol with sesquiterpenoid or phenylpropanoid moieties, named notoethers A–H (1–8) and notoincisols A–C (9–11), respectively. Notoincisol B (10) and notoincisol C (11) represent two new carbon skeletons. When tested for PPARγ activation in a luciferase reporter assay with HEK-293 cells, notoethers A–C (1–3), notoincisol A (9), and notoincisol B (10) showed promising agonistic activity (EC50 values of 1.7 to 2.3 μM). In addition, notoincisol A (9) exhibited inhibitory activity on NO production of stimulated RAW 264.7 macrophages. PMID:25333853

  5. Identity of Endogenous NMDAR Glycine Site Agonist in Amygdala Is Determined by Synaptic Activity Level

    PubMed Central

    Li, Yan; Sacchi, Silvia; Pollegioni, Loredano; Basu, Alo C.; Coyle, Joseph T.; Bolshakov, Vadim Y.

    2013-01-01

    Mechanisms of NMDA receptor-dependent synaptic plasticity contribute to the acquisition and retention of conditioned fear memory. However, synaptic rules which may determine the extent of NMDA receptor activation in the amygdala, a key structure implicated in fear learning, remain unknown. Here we show that the identity of the NMDAR glycine site agonist at synapses in the lateral nucleus of the amygdala may depend on the level of synaptic activation. Tonic activation of NMDARs at synapses in the amygdala under low-activity conditions is supported by ambient D-serine, whereas glycine may be released from astrocytes in response to afferent impulses. The release of glycine may decode the increases in afferent activity levels into enhanced NMDAR-mediated synaptic events, serving an essential function in the induction of NMDAR-dependent long-term potentiation in fear conditioning pathways. PMID:23612301

  6. Design and Synthesis of Highly Active Peroxisome Proliferator-Activated Receptor (PPAR) ?/? Inverse Agonists with Prolonged Cellular Activity.

    PubMed

    Toth, Philipp M; Lieber, Sonja; Scheer, Frithjof M; Schumann, Tim; Schober, Yvonne; Nockher, Wolfgang A; Adhikary, Till; Mller-Brsselbach, Sabine; Mller, Rolf; Diederich, Wibke E

    2016-03-01

    Based on 3-(((4-(hexylamino)-2-methoxyphenyl)amino)sulfonyl)-2-thiophenecarboxylic acid methyl ester (ST247, compound 2), a recently described peroxisome proliferator-activated receptor (PPAR)?/?-selective inverse agonist, we designed and synthesized a series of structurally related ligands. The structural modifications presented herein ultimately resulted in a series of ligands that display increased cellular activity relative to 2. Moreover, with methyl 3-(N-(2-(2-ethoxyethoxy)-4-(hexylamino)phenyl)sulfamoyl)thiophene-2-carboxylate (PT-S264, compound 9?u), biologically relevant plasma concentrations in mice were achieved. The compounds presented in this study will provide useful novel tools for future investigations addressing the role of PPAR?/? in physiological and pathophysiological processes. PMID:26864558

  7. Synthesis, identification, and biological activity of metabolites of two novel selective S1P1 agonists.

    PubMed

    Xiao, Qiong; Jin, Jing; Wang, Xiaojian; Hu, Jinping; Xi, Meiyang; Tian, Yulin; Yin, Dali

    2016-05-15

    SYL927 and SYL930 are selective S1P1 agonists under preclinical development. However, during their pharmacokinetic studies we detected two metabolites in rat blood that were tentatively identified as monohydroxylated metabolites of SYL927 and SYL930 based on LC-MS/MS data. In this study, we designed and synthesized possible monohydroxylated products 6a-e and used them as references to confirm the structures of the two metabolites detected by LC-MS/MS. We also evaluated the in vitro and in vivo biological activities of these two metabolites. PMID:27068143

  8. Lignans from the Fruits of Melia toosendan and Their Agonistic Activities on Melatonin Receptor MT1.

    PubMed

    Wang, Hao; Geng, Chang-An; Xu, Hong-Bo; Huang, Xiao-Yan; Ma, Yun-Bao; Yang, Cai-Yan; Zhang, Xue-Mei; Chen, Ji-Jun

    2015-07-01

    Investigation on the fruits of Melia toosendan afforded seven new lignans (1-7), along with seventeen known compounds (8-24). The structures of the new compounds, involving four neo-lignans (1-4), two sesquilignans (5-6), and a nor-lignan (7), were elucidated based on extensive spectroscopic analyses (high-resolution electrospray ionization mass spectra, ultraviolet, infrared, one-dimensional and two-dimensional nuclear magnetic resonance). Compound 24 exhibited activity on melatonin receptor type 1 with an agonistic rate of 57.77% at 1.02 mM according to the assay on HEK293 cell lines in vitro. PMID:26085048

  9. Quantitative structure-activity relationship modeling of growth hormone secretagogues agonist activity of some tetrahydroisoquinoline 1-carboxamides.

    PubMed

    Caballero, Julio; Zampini, Fabio M; Collina, Simona; Fernández, Michael

    2007-01-01

    Growth hormone secretagogue agonist activities for a data set of 45 tetrahydroisoquinoline 1-carboxamides were modeled using several kinds of molecular descriptors from dragon software. A linear model with six variables selected from a large pool of two-dimensional descriptors described 80% of cross-validation data variance. Similar results were found for a model obtained from a pool of three-dimensional descriptors. Size and hydrophilicity-related atomic properties such as mass, polarizability, and van der Waals volume were determined to be the most relevant for the differential growth hormone secretagogue agonist activities of the compounds studied. In addition, Artificial Neural Networks were trained using optimum variables from the linear models; however, they were found to overfit the data and resulted in similar or lower predictive power. PMID:17313457

  10. The pain receptor TRPV1 displays agonist-dependent activation stoichiometry

    PubMed Central

    Hazan, Adina; Kumar, Rakesh; Matzner, Henry; Priel, Avi

    2015-01-01

    The receptor channel TRPV1 (Transient Receptor Potential Vanilloid 1) is expressed by primary afferent sensory neurons of the pain pathway, where it functions as a sensor of noxious heat and various chemicals, including eicosanoids, capsaicin, protons and peptide toxins. Comprised of four identical subunits that organize into a non-selective cationic permeable channel, this receptor has a variety of binding sites responsible for detecting their respective agonists. Although its physiological role as a chemosensor has been described in detail, the stoichiometry of TRPV1 activation by its different ligands remains unknown. Here, we combined the use of concatemeric constructs harboring mutated binding sites with patch-clamp recordings in order to determine the stoichiometry for TRPV1 activation through the vanilloid binding site and the outer-pore domain by capsaicin and protons, respectively. We show that, while a single capsaicin-bound subunit was sufficient to achieve a maximal open-channel lifetime, all four proton-binding sites were required. Thus, our results demonstrate a distinct stoichiometry of TRPV1 activation through two of its different agonist-binding domains. PMID:26194846

  11. The pain receptor TRPV1 displays agonist-dependent activation stoichiometry.

    PubMed

    Hazan, Adina; Kumar, Rakesh; Matzner, Henry; Priel, Avi

    2015-01-01

    The receptor channel TRPV1 (Transient Receptor Potential Vanilloid 1) is expressed by primary afferent sensory neurons of the pain pathway, where it functions as a sensor of noxious heat and various chemicals, including eicosanoids, capsaicin, protons and peptide toxins. Comprised of four identical subunits that organize into a non-selective cationic permeable channel, this receptor has a variety of binding sites responsible for detecting their respective agonists. Although its physiological role as a chemosensor has been described in detail, the stoichiometry of TRPV1 activation by its different ligands remains unknown. Here, we combined the use of concatemeric constructs harboring mutated binding sites with patch-clamp recordings in order to determine the stoichiometry for TRPV1 activation through the vanilloid binding site and the outer-pore domain by capsaicin and protons, respectively. We show that, while a single capsaicin-bound subunit was sufficient to achieve a maximal open-channel lifetime, all four proton-binding sites were required. Thus, our results demonstrate a distinct stoichiometry of TRPV1 activation through two of its different agonist-binding domains. PMID:26194846

  12. Assessing the agonist profiles of the prostacyclin analogues treprostinil and naxaprostene, particularly their DP₁ activity.

    PubMed

    Syed, Nawazish-i-Husain; Jones, Robert L

    2015-04-01

    In this study, the inhibitory profiles of the prostacyclin analogues treprostinil and naxaprostene on several isolated smooth muscle preparations have been investigated. Treprostinil was an agonist for prostanoid DP1, EP2 and IP receptors, but not EP4 receptors; its DP1 potency was only 3-4 times less than PGD2 itself. Naxaprostene was much more selective for IP receptors and tended towards partial agonism. Treprostinil is a 13,14-dihydro analogue and the role of conformation around C12-15 in controlling agonist specificity is debated; the synthesis of new analogues is proposed and possible clinical usage discussed. In terms of selective prostanoid antagonists employed, BW-A868C/MK-0524 (DP1), ACA-23 (EP2) and GW-627368 (EP4) were found fit for purpose. However, the IP antagonist RO-1138452 was compromised by α1 and α2-adrenoceptor-mediated contractile activity on rat tail artery and anti-muscarinic activity on mouse trachea. There is a need for IP receptor antagonists with better selectivity and higher affinity. PMID:25542069

  13. Agonist-activated Ca2+ influx occurs at stable plasma membrane and endoplasmic reticulum junctions

    PubMed Central

    Treves, Susan; Vukcevic, Mirko; Griesser, Johanna; Armstrong, Clara-Franzini; Zhu, Michael X.; Zorzato, Fancesco

    2010-01-01

    Junctate is a 33 kDa integral protein of sarco(endo)plasmic reticulum membranes that forms a macromolecular complex with inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptors and TRPC3 channels. TIRF microscopy shows that junctate enhances the number of fluorescent puncta on the plasma membrane. The size and distribution of these puncta are not affected by the addition of agonists that mobilize Ca2+ from Ins(1,4,5)P3-sensitive stores. Puncta are associated with a significantly larger number of peripheral junctions between endoplasmic reticulum and plasma membrane, which are further enhanced upon stable co-expression of junctate and TRPC3. The gap between the membranes of peripheral junctions is bridged by regularly spaced electron-dense structures of 10 nm. Ins(1,4,5)P3 inhibits the interaction of the cytoplasmic N-terminus of junctate with the ligand-binding domain of the Ins(1,4,5)P3 receptor. Furthermore, Ca2+ influx evoked by activation of Ins(1,4,5)P3 receptors is increased where puncta are located. We conclude that stable peripheral junctions between the plasma membrane and endoplasmic reticulum are the anatomical sites of agonist-activated Ca2+ entry. PMID:21062895

  14. Small-molecule nociceptin receptor agonist ameliorates mast cell activation and pain in sickle mice.

    PubMed

    Vang, Derek; Paul, Jinny A; Nguyen, Julia; Tran, Huy; Vincent, Lucile; Yasuda, Dennis; Zaveri, Nurulain T; Gupta, Kalpna

    2015-12-01

    Treatment of pain with morphine and its congeners in sickle cell anemia is suboptimal, warranting the need for analgesics devoid of side effects, addiction and tolerance liability. Small-molecule nociceptin opioid receptor ligands show analgesic efficacy in acute and chronic pain models. We show that AT-200, a high affinity nociceptin opioid receptor agonist with low efficacy at the mu opioid receptor, ameliorated chronic and hypoxia/reoxygenation-induced mechanical, thermal and deep tissue/musculoskeletal hyperalgesia in HbSS-BERK sickle mice. The antinociceptive effect of AT-200 was antagonized by SB-612111, a nociceptin opioid receptor antagonist, but not naloxone, a non-selective mu opioid receptor antagonist. Daily 7-day treatment with AT-200 did not develop tolerance and showed a sustained anti-nociceptive effect, which improved over time and led to reduced plasma serum amyloid protein, neuropeptides, inflammatory cytokines and mast cell activation in the periphery. These data suggest that AT-200 ameliorates pain in sickle mice via the nociceptin opioid receptor by reducing inflammation and mast cell activation without causing tolerance. Thus, nociceptin opioid receptor agonists are promising drugs for treating pain in sickle cell anemia. PMID:26294734

  15. Small-molecule nociceptin receptor agonist ameliorates mast cell activation and pain in sickle mice

    PubMed Central

    Vang, Derek; Paul, Jinny A.; Nguyen, Julia; Tran, Huy; Vincent, Lucile; Yasuda, Dennis; Zaveri, Nurulain T.; Gupta, Kalpna

    2015-01-01

    Treatment of pain with morphine and its congeners in sickle cell anemia is suboptimal, warranting the need for analgesics devoid of side effects, addiction and tolerance liability. Small-molecule nociceptin opioid receptor ligands show analgesic efficacy in acute and chronic pain models. We show that AT-200, a high affinity nociceptin opioid receptor agonist with low efficacy at the mu opioid receptor, ameliorated chronic and hypoxia/reoxygenation-induced mechanical, thermal and deep tissue/musculoskeletal hyperalgesia in HbSS-BERK sickle mice. The antinociceptive effect of AT-200 was antagonized by SB-612111, a nociceptin opioid receptor antagonist, but not naloxone, a non-selective mu opioid receptor antagonist. Daily 7-day treatment with AT-200 did not develop tolerance and showed a sustained anti-nociceptive effect, which improved over time and led to reduced plasma serum amyloid protein, neuropeptides, inflammatory cytokines and mast cell activation in the periphery. These data suggest that AT-200 ameliorates pain in sickle mice via the nociceptin opioid receptor by reducing inflammation and mast cell activation without causing tolerance. Thus, nociceptin opioid receptor agonists are promising drugs for treating pain in sickle cell anemia. PMID:26294734

  16. Berberine is a potent agonist of peroxisome proliferator activated receptor alpha.

    PubMed

    Yu, Huarong; Li, Changqing; Yang, Junqing; Zhang, Tao; Zhou, Qixin

    2016-01-01

    Although berberine has hypolipidemic effects with a high affinity to nuclear proteins, the underlying molecular mechanism for this effect remains unclear. Here, we determine whether berberine is an agonist of peroxisome proliferator-activated receptor alpha (PPARalpha), with a lipid-lowering effect. The cell-based reporter gene analysis showed that berberine selectively activates PPARalpha (EC50 =0.58 mM, Emax =102.4). The radioligand binding assay shows that berberine binds directly to the ligand-binding domain of PPARalpha (Ki=0.73 mM) with similar affinity to fenofibrate. The mRNA and protein levels of CPT-Ialpha gene from HepG2 cells and hyperlipidemic rat liver are remarkably up-regulated by berberine, and this effect can be blocked by MK886, a non-competitive antagonist of PPARalpha. A comparison assay in which berberine and fenofibrate were used to treat hyperlipidaemic rats for three months shows that these drugs produce similar lipid-lowering effects, except that berberine increases high-density lipoprotein cholesterol more effectively than fenofibrate. These findings provide the first evidence that berberine is a potent agonist of PPARalpha and seems to be superior to fenofibrate for treating hyperlipidemia. PMID:27100490

  17. Effects of Peroxisome Proliferator-Activated Receptor-δ Agonist on Cardiac Healing after Myocardial Infarction

    PubMed Central

    Park, Jeong Rang; Ahn, Jong Hwa; Jung, Myeong Hee; Koh, Jin-Sin; Park, Yongwhi; Hwang, Seok-Jae; Jeong, Young-Hoon; Kwak, Choong Hwan; Lee, Young Soo; Seo, Han Geuk; Kim, Jin Hyun; Hwang, Jin-Yong

    2016-01-01

    Peroxisome proliferator-activated receptor-delta (PPAR-δ)-dependent signaling is associated with rapid wound healing in the skin. Here, we investigated the therapeutic effects of PPAR-δ-agonist treatment on cardiac healing in post-myocardial infarction (MI) rats. Animals were assigned to the following groups: sham-operated control group, left anterior descending coronary artery ligation (MI) group, or MI with administration of the PPAR-δ agonist GW610742 group. GW610742 (1 mg/kg) was administrated intraperitoneally after the operation and repeated every 3 days. Echocardiographic data showed no differences between the two groups in terms of cardiac function and remodeling until 4 weeks. However, the degrees of angiogenesis and fibrosis after MI were significantly higher in the GW610742-treated rats than in the untreated MI rats at 1 week following MI, which changes were not different at 2 weeks after MI. Naturally, PPAR-δ expression in infarcted myocardium was highest increased in 3 day after MI and then disappeared in 14 day after MI. GW610742 increased myofibroblast differentiation and transforming growth factor-beta 2 expression in the infarct zone at 7 days after MI. GW610742 also increased bone marrow-derived mesenchymal stem cell (MSC) recruitment in whole myocardium, and increased serum platelet-derived growth factor B, stromal-derived factor-1 alpha, and matrix metallopeptidase 9 levels at day 3 after MI. PPAR-δ agonists treatment have the temporal effect on early fibrosis of infarcted myocardium, which might not sustain the functional and structural beneficial effect. PMID:26862756

  18. Long Receptor Residence Time of C26 Contributes to Super Agonist Activity at the Human β2 Adrenoceptor.

    PubMed

    Rosethorne, Elizabeth M; Bradley, Michelle E; Gherbi, Karolina; Sykes, David A; Sattikar, Afrah; Wright, John D; Renard, Emilie; Trifilieff, Alex; Fairhurst, Robin A; Charlton, Steven J

    2016-04-01

    Super agonists produce greater functional responses than endogenous agonists in the same assay, and their unique pharmacology is the subject of increasing interest and debate. We propose that receptor residence time and the duration of receptor signaling contribute to the pharmacology of super agonism. We have further characterized the novel β2 adrenoceptor agonist C26 (7-[(R)-2-((1R,2R)-2-benzyloxycyclopentylamino)-1-hydroxyethyl]-4-hydroxybenzothiazolone), which displays higher intrinsic activity than the endogenous ligand adrenaline in cAMP accumulation, β-arrestin-2 recruitment, and receptor internalization assays. C26 recruited β-arrestin-2, and internalized the Green Fluorescent Protein (GFP)-taggedβ2 adrenoceptor at a slow rate, with half-life (t1/2) values of 0.78 ± 0.1 and 0.78 ± 0.04 hours, respectively. This was compared with 0.31 ± 0.04 and 0.34 ± 0.01 hours for adrenaline-mediated β-arrestin-2 recruitment and GFP-β2 internalization, respectively. The slower rate for C26 resulted in levels of β-arrestin-2 recruitment increasing up to 4-hour agonist incubation, at which point the intrinsic activity was determined to be 124.3 ± 0.77% of the adrenaline response. In addition to slow functional kinetics, C26 displayed high affinity with extremely slow receptor dissociation kinetics, giving a receptor residence half-life of 32.7 minutes at 37°C, which represents the slowest dissociation rate we have observed for any β2 adrenoceptor agonist tested to date. In conclusion, we propose that the gradual accumulation of long-lived active receptor complexes contributes to the increased intrinsic activity of C26 over time. This highlights the need to consider the temporal aspects of agonist binding and signaling when characterizing ligands as super agonists. PMID:26772612

  19. Evaluation of the beta 2 adrenoceptor agonist/antagonist activity of formoterol and salmeterol.

    PubMed Central

    Grove, A.; Lipworth, B. J.

    1996-01-01

    BACKGROUND: Salmeterol and formoterol have a lower intrinsic activity at beta 2 receptors than isoprenaline in human bronchus in vitro. The aim of the present study was to evaluate in vivo the beta 2 agonist/antagonist activity of salmeterol and formoterol at rest with low endogenous adrenergic tone, on exercise with raised endogenous adrenergic tone, and in the presence of fenoterol, an exogenous full beta 2 receptor agonist. METHODS: Eight normal subjects were randomised to receive single doses of placebo, salmeterol 300 micrograms, formoterol 72 micrograms, or propranolol 80 mg at weekly intervals. beta 2 adrenoceptor responses were evaluated at rest, at peak exercise, and after treatment with fenoterol 2.4 mg. RESULTS: At rest salmeterol and formoterol exhibited equivalent beta 2 agonist activity with regard to decrease in serum potassium levels and increase in finger tremor, with propranolol having no effect. Salmeterol and formoterol, like propranolol, potentiated the hyperkalaemic delta response to exercise compared with placebo, consistent with beta 2 antagonism: (mean difference and 95% confidence interval (CI) compared with placebo) salmeterol 0.20 (0.02 to 0.38) mmol/l, formoterol 0.17 (0.00 to 0.34) mmol/l, propranolol 0.45 (0.08 to 0.82) mmol/l. Propranolol blunted the heart rate delta response to exercise, consistent with beta 1 blockade, whilst salmeterol and formoterol had no effect. Salmeterol and formoterol, like propranolol, attenuated the hypokalaemic, tremor, and heart rate delta responses to fenoterol compared with placebo, in keeping with beta 2 blockade: potassium, salmeterol 0.18 (0.0 to 0.36) mmol/l, formoterol 0.17 (-0.03 to 0.37) mmol/l, propranolol 0.80 (0.54 to 1.06) mmol/l; tremor, salmeterol -0.69 (-1.26 to -0.12) log units, formoterol -0.71 (-1.53 to 0.11) log units, propranolol -0.85 (-1.66 to -0.04) log units; heart rate, salmeterol -6 (-13 to 1) beats/min, formoterol -10 (-19 to -1) beats/min, propranolol -18 (-29 to -7) beats/min. CONCLUSIONS: At rest with low endogenous adrenergic tone salmeterol and formoterol showed equivalent beta 2 mediated agonist activity in terms of serum potassium and finger tremor responses. In the presence of raised endogenous adrenergic tone at peak exercise and in the presence of fenoterol (an exogenous full beta 2 receptor agonist), salmeterol and formoterol, like propranolol, exhibited beta 2 receptor antagonism as evidenced by their attenuation of beta 2 receptor mediated responses. The degree of beta 2 blockade with formoterol and salmeterol was comparable but less than with propranolol. The relevance of these findings at extrapulmonary beta 2 receptors with regard to airway beta 2 responses remains unclear and warrants further investigation. PMID:8658370

  20. 5-HT4 receptor agonists enhance both cholinergic and nitrergic activities in human isolated colon circular muscle.

    PubMed

    Cellek, S; John, A K; Thangiah, R; Dass, N B; Bassil, A K; Jarvie, E M; Lalude, O; Vivekanandan, S; Sanger, G J

    2006-09-01

    Previous studies have demonstrated mixed inhibitory and facilitatory effects of 5-hydroxytryptamine-4 (5-HT(4)) receptor agonists on electrical field stimulation (EFS)-induced responses in human isolated colon. Here we report three types of responses to EFS in human isolated colon circular muscle: monophasic cholinergic contraction during EFS, biphasic response (nitrergic relaxation during EFS followed by cholinergic contraction after termination of EFS) and triphasic response (cholinergic contraction followed by nitrergic relaxation during EFS and a tachykininergic contraction after EFS). The effects of two 5-HT(4) receptor agonists, prucalopride and tegaserod were then investigated on monophasic responses only. Each compound inhibited contractions during EFS in a concentration-dependent manner. In the presence of N(omega)-nitro-l-arginine methyl ester (l-NAME) however, prucalopride and tegaserod enhanced the contractions in a concentration-dependent manner. In strips where the tone was elevated with substance-P and treated with scopolamine, EFS-induced relaxations were enhanced by the two agonists. The above observed effects by the two agonists were abolished by 5-HT(4) receptor antagonist SB-204070. The two agonists did not alter the tone raised by substance-P in the presence of scopolamine and l-NAME and did not affect carbachol-induced contractions in the presence of tetrodotoxin. These results suggest that in the circular muscle of human colon, 5-HT(4) receptor agonists simultaneously facilitate the activity of neurones which release the inhibitory and excitatory neurotransmitters, nitric oxide and acetylcholine respectively. PMID:16918765

  1. Replacement of the hydrophobic part of 9-cis-retinoic acid with cyclic terpenoid moiety results in RXR-selective agonistic activity.

    PubMed

    Okitsu, Takashi; Sato, Kana; Iwatsuka, Kinya; Sawada, Natsumi; Nakagawa, Kimie; Okano, Toshio; Yamada, Shoya; Kakuta, Hiroki; Wada, Akimori

    2011-05-01

    Retinoid X receptor (RXR) agonists are interesting candidates for the treatment of metabolic syndrome. 9-Cis-retinoic acid (9cRA: 1) is a natural RXR agonist, that also works as a retinoic acid receptor (RAR) agonist. This fact prompted us to study the structure-activity relationship (SAR) of RXR agonists derived from 1. Though 3 and 4, in which the cyclohexene part of 1 is replaced with bulkier hydrophobic moieties, show RXR-selective agonistic activity, some analogs containing other ring structures show RAR agonistic activity. Thus, we were interested in establishing what kind of ring skeleton is required for RXR-selective agonistic activity. In this study, we systematically prepared 5 and 6, in which the cyclohexene ring of 1 is replaced with various cyclic terpenoid moieties, and evaluated their RXR and RAR agonistic activities. Our previously reported CsF-promoted Stille coupling reaction was employed as a key step for the comprehensive synthesis of 5 and 6. The results of transcriptional assay showed that compounds 5b-f, which possess a menthane skeleton, exhibit RXR-selective agonistic activity. These results should be helpful for the design of superior RXR-selective agonists based on the structure of 1. PMID:21489804

  2. Structural basis for constitutive activity and agonist-induced activation of the enteroendocrine fat sensor GPR119

    PubMed Central

    Engelstoft, M S; Norn, C; Hauge, M; Holliday, N D; Elster, L; Lehmann, J; Jones, R M; Frimurer, T M; Schwartz, T W

    2014-01-01

    Background and Purpose GPR119 is a Gαs-coupled 7TM receptor activated by endogenous lipids such as oleoylethanolamide (OEA) and by the dietary triglyceride metabolite 2-monoacylglycerol. GPR119 stimulates enteroendocrine hormone and insulin secretion. But despite massive drug discovery efforts in the field, very little is known about the basic molecular pharmacology of GPR119. Experimental Approach GPR119 receptor signalling was studied in transfected cells. Mutational mapping (30 mutations in 23 positions) was performed on residues required for ligand-independent and agonist-induced GPR119 activation (AR231453 and OEA). Novel Rosetta-based receptor modelling was applied, using a composite template approach with segments from different X-ray structures and fully flexible ligand docking. Key Results The increased signalling induced by increasing the cell surface expression of GPR119 in the absence of agonist and the inhibitory effect of two synthetic inverse agonists demonstrated that GRP119 signals with a high degree of constitutive activity through the Gαs pathway. The mutational maps for AR231453 and OEA were very similar and, surprisingly, also similar to the mutational map for residues affecting the constitutive signalling – albeit with key differences. Surprisingly, almost all residues in extracellular loop-2b were important for the constitutive activity. The molecular modelling and docking demonstrated that AR231453 binds in a ‘vertical’ pocket in between mutational hits reaching from the centre of the receptor out to extracellular loop-2b. Conclusions and Implications The high constitutive activity of GPR119 should be taken into account in future drug discovery efforts, which can now be guided by the detailed knowledge of the physiochemical properties of the extended ligand-binding pocket. PMID:25117266

  3. The Toll-Like Receptor Agonist Imiquimod Is Active against Prions

    PubMed Central

    Beringue, Vincent; Soubigou, Flavie; Pang, Yanhong; Desban, Nathalie; Massacrier, Catherine; Morel, Yannis; Paturel, Carine; Contesse, Marie-Astrid; Bouaziz, Serge; Sanyal, Suparna; Galons, Hervé; Blondel, Marc; Voisset, Cécile

    2013-01-01

    Using a yeast-based assay, a previously unsuspected antiprion activity was found for imiquimod (IQ), a potent Toll-like receptor 7 (TLR7) agonist already used for clinical applications. The antiprion activity of IQ was first detected against yeast prions [PSI+] and [URE3], and then against mammalian prion both ex vivo in a cell-based assay and in vivo in a transgenic mouse model for prion diseases. In order to facilitate structure-activity relationship studies, we conducted a new synthetic pathway which provides a more efficient means of producing new IQ chemical derivatives, the activity of which was tested against both yeast and mammalian prions. The comparable antiprion activity of IQ and its chemical derivatives in the above life forms further emphasizes the conservation of prion controlling mechanisms throughout evolution. Interestingly, this study also demonstrated that the antiprion activity of IQ and IQ-derived compounds is independent from their ability to stimulate TLRs. Furthermore, we found that IQ and its active chemical derivatives inhibit the protein folding activity of the ribosome (PFAR) in vitro. PMID:23977222

  4. Catalposide is a natural agonistic ligand of peroxisome proliferator-activated receptor-{alpha}

    SciTech Connect

    Lee, Ji Hae; Jun, Hee-jin; Hoang, Minh-Hien; Jia, Yaoyao; Department of Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 ; Han, Xiang Hua; Lee, Dong-Ho; Lee, Hak-Ju; Hwang, Bang Yeon; Lee, Sung-Joon; Department of Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-713

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Catalposide is a novel ligand for PPAR{alpha}. Black-Right-Pointing-Pointer Cell stimulated with catalposide improved fatty acid uptake, regulated target genes in fatty acid {beta}-oxidation and synthesis. Black-Right-Pointing-Pointer Catalposdie reduces hepatic triacylglycerides. Black-Right-Pointing-Pointer Theses demonstrate catalposide could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: Peroxisome proliferator-activated receptor-alpha (PPAR{alpha}) is a nuclear receptor that regulates the expression of genes related to cellular lipid uptake and oxidation. Thus, PPAR{alpha} agonists may be important in the treatment of hypertriglyceridemia and hepatic steatosis. In this study, we demonstrated that catalposide is a novel natural PPAR{alpha} agonist, identified from reporter gene assay-based activity screening with approximately 900 natural plant and seaweed extracts. Results of time-resolved fluorescence resonance energy transfer analyses suggested that the compound interacted directly with the ligand-binding domain of PPAR{alpha}. Cultured hepatocytes stimulated with catalposide exhibited significantly reduced cellular triglyceride concentrations, by 21%, while cellular uptake of fatty acids was increased, by 70% (P < 0.05). Quantitative PCR analysis revealed that the increase in cellular fatty acid uptake was due to upregulation of fatty acid transporter protein-4 (+19% vs. the control) in cells stimulated with catalposide. Additionally, expression of genes related to fatty acid oxidation and high-density lipoprotein metabolism were upregulated, while that of genes related to fatty acid synthesis were suppressed. In conclusion, catalposide is hypolipidemic by activation of PPAR{alpha} via a ligand-mediated mechanism that modulates the expression of in lipid metabolism genes in hepatocytes.

  5. Specific activation of the TLR1-TLR2 heterodimer by small-molecule agonists

    PubMed Central

    Cheng, Kui; Gao, Meng; Godfroy, James I.; Brown, Peter N.; Kastelowitz, Noah; Yin, Hang

    2015-01-01

    Toll-like receptor (TLR) agonists activate both the innate and the adaptive immune systems. These TLR agonists have been exploited as potent vaccine adjuvants and antitumor agents. We describe the identification and characterization of a small molecule, N-methyl-4-nitro-2-(4-(4-(trifluoromethyl)phenyl)-1H-imidazol-1-yl)aniline (CU-T12-9), that directly targets TLR1/2 to initiate downstream signaling. CU-T12-9 specifically induces TLR1/2 activation, which can be blocked by either the anti-hTLR1 or the anti-hTLR2 antibody, but not the anti-hTLR6 antibody. Using a variety of different biophysical assays, we have demonstrated the binding mode of CU-T12-9. By binding to both TLR1 and TLR2, CU-T12-9 facilitates the TLR1/2 heterodimeric complex formation, which in turn activates the downstream signaling. Fluorescence anisotropy assays revealed competitive binding to the TLR1/2 complex between CU-T12-9 and Pam3CSK4 with a half-maximal inhibitory concentration (IC50) of 54.4 nM. Finally, we showed that CU-T12-9 signals through nuclear factor κB (NF-κB) and invokes an elevation of the downstream effectors tumor necrosis factor–α (TNF-α), interleukin-10 (IL-10), and inducible nitric oxide synthase (iNOS). Thus, our studies not only provide compelling new insights into the regulation of TLR1/2 signaling transduction but also may facilitate future therapeutic developments. PMID:26101787

  6. Adhesion G protein-coupled receptors are activated by exposure of a cryptic tethered agonist

    PubMed Central

    Stoveken, Hannah M.; Hajduczok, Alexander G.; Xu, Lei; Tall, Gregory G.

    2015-01-01

    The large class of adhesion G protein-coupled receptors (aGPCRs) bind extracellular matrix or neighboring cell-surface ligands to regulate organ and tissue development through an unknown activation mechanism. We examined aGPCR activation using two prototypical aGPCRs, GPR56 and GPR110. Active dissociation of the noncovalently bound GPR56 or GPR110 extracellular domains (ECDs) from the respective seven-transmembrane (7TM) domains relieved an inhibitory influence and permitted both receptors to activate defined G protein subtypes. After ECD displacement, the newly revealed short N-terminal stalk regions of the 7TM domains were found to be essential for G protein activation. Synthetic peptides comprising these stalks potently activated GPR56 or GPR110 in vitro or in cells, demonstrating that the stalks comprise a tethered agonist that was encrypted within the ECD. Establishment of an aGPCR activation mechanism provides a rational platform for the development of aGPCR synthetic modulators that could find clinical utility toward aGPCR-directed disease. PMID:25918380

  7. Imidazoquinoline TLR8 agonists activate human newborn monocytes and dendritic cells via adenosine-refractory and caspase-1-dependent pathways

    PubMed Central

    Philbin, Victoria J.; Dowling, David J.; Gallington, Leighanne C.; Corts, Guadalupe; Tan, Zhen; Suter, Eugnie E.; Chi, Kevin W.; Shuckett, Ariel; Stoler-Barak, Liat; Tomai, Mark; Miller, Richard L.; Mansfield, Keith; Levy, Ofer

    2012-01-01

    Background Newborns suffer frequent infection and manifest impaired vaccine responses, motivating a search for neonatal vaccine adjuvants. Alum is a neonatal adjuvant, but may confer a Th2 bias. Toll-like receptor (TLR) agonists are candidate adjuvants, but human neonatal cord blood monocytes (Mos) demonstrate impaired Th1-polarizing responses to many TLR agonists due to plasma adenosine acting via cAMP. TLR8 agonists, including imidazoquinolines (IMQs) such as the small synthetic 3M-002, induce adult-level TNF from neonatal Mos, but the scope and mechanisms of IMQ-induced activation of neonatal Mos and Mo-derived dendritic cells (MoDCs) have not been reported. Objectives To characterize IMQ-induced activation of neonatal Mos and MoDCs. Methods Neonatal cord and adult peripheral blood Mos and MoDCs were cultured in autologous plasma; Alum- and TLR agonist-induced cytokines and co-stimulatory molecules were measured. TLR8 and inflammasome function were assayed using siRNA and western blotting/caspase-1 inhibitory peptide, respectively. The ontogeny of TLR8 agonistinduced cytokine responses was defined in Rhesus macaque whole blood ex vivo. Results IMQs were more potent and effective than Alum at inducing TNF and IL-1? from Mos. 3M-002 induced robust TLR pathway transcriptome activation and Th1-polarizing cytokine production in neonatal and adult Mos and MoDCs, signaling via TLR8 in an adenosine/cAMP- refractory manner. Newborn MoDCs displayed impaired LPS/ATP-induced caspase-1-mediated IL-1? production, but robust 3M-002-induced caspase-1-mediated inflammasome activation independent of exogenous ATP. TLR8-IMQs induced robust TNF and IL-1? in whole blood of Rhesus macaques at birth and infancy. Conclusions IMQ TLR8 agonists engage adenosine-refractory TLR8 and inflammasome pathways to induce robust Mo and MoDC activation and represent promising neonatal adjuvants. PMID:22521247

  8. Autoantibodies to the δ-Opioid Receptor Function as Opioid Agonists and Display Immunomodulatory Activity

    PubMed Central

    Ranganathan, Parvathi; Chen, Hao; Adelman, Miranda K.; Schluter, Samuel F.

    2010-01-01

    In this report, we show that affinity purified human anti-Delta Opioid Receptor (DOR) autoantibodies from IVIG are specific to DOR and possess agonistic properties displayed by their ability to dramatically decrease forskolin stimulated cAMP accumulation. Anti-DOR autoantibody also caused phosphorylation of the opioid receptor. Anti-DOR autoantibody treatment showed a significant reduction in CXCR4 gene expression as well as surface protein expression. In contrast, anti-DOR autoantibody treatment significantly upregulated CCR5 gene and protein expression. The presence of anti-DOR autoantibodies in IVIG and their potent immunomodulatory activity is further evidence to support the crosstalk between the neuroendocrine and immune system. PMID:19879656

  9. Identification of a potent synthetic FXR agonist with an unexpected mode of binding and activation

    SciTech Connect

    Soisson, Stephen M.; Parthasarathy, Gopalakrishnan; Adams, Alan D.; Sahoo, Soumya; Sitlani, Ayesha; Sparrow, Carl; Cui, Jisong; Becker, Joseph W.

    2008-07-08

    The farnesoid X receptor (FXR), a member of the nuclear hormone receptor family, plays important roles in the regulation of bile acid and cholesterol homeostasis, glucose metabolism, and insulin sensitivity. There is intense interest in understanding the mechanisms of FXR regulation and in developing pharmaceutically suitable synthetic FXR ligands that might be used to treat metabolic syndrome. We report here the identification of a potent FXR agonist (MFA-1) and the elucidation of the structure of this ligand in ternary complex with the human receptor and a coactivator peptide fragment using x-ray crystallography at 1.9-{angstrom} resolution. The steroid ring system of MFA-1 binds with its D ring-facing helix 12 (AF-2) in a manner reminiscent of hormone binding to classical steroid hormone receptors and the reverse of the pose adopted by naturally occurring bile acids when bound to FXR. This binding mode appears to be driven by the presence of a carboxylate on MFA-1 that is situated to make a salt-bridge interaction with an arginine residue in the FXR-binding pocket that is normally used to neutralize bound bile acids. Receptor activation by MFA-1 differs from that by bile acids in that it relies on direct interactions between the ligand and residues in helices 11 and 12 and only indirectly involves a protonated histidine that is part of the activation trigger. The structure of the FXR:MFA-1 complex differs significantly from that of the complex with a structurally distinct agonist, fexaramine, highlighting the inherent plasticity of the receptor.

  10. Concomitant activation of adenylyl cyclase suppresses the opposite influences of CB(1) cannabinoid receptor agonists on tyrosine hydroxylase expression.

    PubMed

    Bosier, Barbara; Hermans, Emmanuel; Lambert, Didier M

    2009-01-15

    The CB(1) cannabinoid receptor shows complex interactions with intracellular signalling partners, and responses to cannabinoid ligands are likely to be influenced by concomitant inputs modifying the overall tone of signalling cascades. This appears even more relevant as we previously evidenced opposite regulations of tyrosine hydroxylase (TH) expression by the two common cannabinoid agonists HU 210 and CP 55,940. Therefore, we studied the consequences of manipulating adenylyl cyclase activity with forskolin on the regulation of TH gene transcription in neuroblastoma cells (N1E-115). Reporter gene experiments performed with the luciferase sequence cloned under the control of modified fragments of the TH gene promoter revealed that the AP-1 consensus sequence is essential for cannabinoid-mediated regulation of TH expression. Consistently, inhibition of PKC totally blocked the responses mediated by both HU 210 and CP 55,940. In addition, forskolin which boosts adenylyl cyclase activity remarkably modified the responses to the cannabinoid agonists. Thus, in these conditions, both agonists efficiently reduced TH gene promoter activity, a response requiring functional PKA/CRE-dependent signallings. Finally, the modulations of the promoter were inhibited in pertussis toxin treated cells, suggesting that responses to both agonists are mediated through G(i/o)-dependent mechanisms. Emphasising on the importance of functional selectivity at GPCRs, these data demonstrate that the concomitant activation of adenylyl cyclase by forskolin strongly influences the biochemical responses triggered by distinct cannabinoid agonists. Together our results suggest that the physiological modulation of TH expression by cannabinoid agonists in dopaminergic neurons would be influenced by additional endogenous inputs. PMID:18992715

  11. Selective Cannabinoid Receptor-1 Agonists Regulate Mast Cell Activation in an Oxazolone-Induced Atopic Dermatitis Model

    PubMed Central

    Nam, Gaewon; Jeong, Se Kyoo; Park, Bu Man; Lee, Sin Hee; Kim, Hyun Jong; Hong, Seung-Phil; Kim, Beomjoon

    2016-01-01

    Background Many inflammatory mediators, including various cytokines (e.g. interleukins and tumor necrosis factor [TNF]), inflammatory proteases, and histamine are released following mast cell activation. However, the endogenous modulators for mast cell activation and the underlying mechanism have yet to be elucidated. Endogenous cannabinoids such as palmitoylethanolamide (PEA) and N-arachidonoylethanolamine (anandamide or AEA), were found in peripheral tissues and have been proposed to possess autacoid activity, implying that cannabinoids may downregulate mast cell activation and local inflammation. Objective In order to investigate the effect of cannabinoid receptor-1 (CB1R) agonists on mast cell activation, AEA-derived compounds were newly synthesized and evaluated for their effect on mast cell activation. Methods The effects of selected compounds on FcεRI-induced histamine and β-hexosaminidase release were evaluated in a rat basophilic leukemia cell line (RBL-2H3). To further investigate the inhibitory effects of CB1R agonist in vivo, an oxazolone-induced atopic dermatitis mouse model was exploited. Results We found that CB1R inhibited the release of inflammatory mediators without causing cytotoxicity in RBL-2H3 cells and that CB1R agonists markedly and dose-dependently suppressed mast cell proliferation indicating that CB1R plays an important role in modulating antigen-dependent immunoglobulin E (IgE)-mediated mast cell activation. We also found that topical application of CB1R agonists suppressed the recruitment of mast cells into the skin and reduced the level of blood histamine. Conclusion Our results indicate that CB1R agonists down-regulate mast cell activation and may be used for relieving inflammatory symptoms mediated by mast cell activation, such as atopic dermatitis, psoriasis, and contact dermatitis. PMID:26848215

  12. The effects of agonist and antagonist muscle activation on the knee extension moment-angle relationship in adults and children.

    PubMed

    O'Brien, Thomas D; Reeves, Neil D; Baltzopoulos, Vasilios; Jones, David A; Maganaris, Constantinos N

    2009-08-01

    The present study examined the effect of agonist activation and antagonist co-activation on the shape of the knee extension moment-angle relationship in adults and children. Isometric knee extension maximum voluntary contractions (MVCs) were performed at every 5 degrees of knee flexion between 55 degrees and 90 degrees (full extension = 0 degrees) by ten men, ten women, ten boys and ten girls. For each trial, the knee extensors' voluntary activation level was quantified using magnetic stimulation and the level of antagonist co-activation was quantified from their electromyographical activity. Peak MVC moment was greater for men (264 +/- 63 N m) than women (177 +/- 60 N m), and greater for adults than children (boys 78 +/- 17 N m, girls 91 +/- 28 N m) (p < 0.01). The agonistic activation level was greater for adults (approximately 85%) than children (approximately 70%). Similarly, antagonist co-activation was greater for adults than children, but relative to the agonist moment there were no differences between groups (all groups 7-8%). Correcting the peak moment for agonist and antagonist activation levels resulted in moments produced by fully activated agonist muscles of 334 +/- 83, 229 +/- 70, 114.2 +/- 32 and 147 +/- 46 N m, for men, women, boys and girls, respectively. Although correcting for shifts in joint angle during contraction altered the angle of peak moment by approximately 10 degrees (p < 0.01), the peak moment occurred at approximately 60 degrees for all groups. Changes in tendon stiffness, muscle size and architecture, and the pattern of the moment arm-angle relationship may in combination occur so that as children develop and mature into adults the shape of the moment-angle relationship is not altered. PMID:19471955

  13. Identification of potent and selective neuropeptide Y Y(1) receptor agonists with orexigenic activity in vivo.

    PubMed

    Mullins, D; Kirby, D; Hwa, J; Guzzi, M; Rivier, J; Parker, E

    2001-09-01

    Neuropeptide Y (NPY) binds to a family of G-protein coupled receptors termed Y(1), Y(2), Y(3), Y(4), Y(5), and y(6). The use of various receptor subtype-selective agonists and antagonists has facilitated identification of the receptor subtypes responsible for mediating many of the biological effects of NPY. For example, the potent orexigenic activity of NPY is believed to be mediated by both the Y(1) and Y(5) receptor subtypes. Several selective Y(5) receptor agonists that stimulate food intake in rodents are available, but no selective Y(1) receptor agonist has been reported. We have identified several NPY analogs that bind the NPY Y(1) receptor with high affinity and exhibit full agonist activity, measured as inhibition of forskolin-stimulated cAMP production in cells expressing the cloned NPY Y(1) receptor. [D-Arg(25)]-NPY, [D-His(26)]-NPY, Des-AA(10--17)[Cys(7,21),Pro(34)]-NPY, Des-AA(11--18)[Cys(7,21),D-Lys(9)(Ac)]-NPY, Des-AA(11--18)[Cys(7,21),D-Lys(9)(Ac),Pro(34)]-NPY, Des-AA(11--18)[Cys(7,21),D-Lys(9)(Ac),D-His(26)]-NPY and Des-AA(11--18)[Cys(7,21),D-Lys(9)(Ac),D-His(26), Pro(34)]-NPY bind the NPY Y(1) receptor with K(i) values of 0.9 +/- 0.2, 2.0 +/- 0.3, 0.2 +/- 0.05, 0.7 +/- 0.1, 0.2 +/- 0.01, 2.2 +/- 0.3, and 1.2 +/- 0.3 nM, respectively, and inhibit forskolin-stimulated cAMP production with EC(50) values of 0.2 +/- 0.02, 0.5 +/- 0.04, 0.3 +/- 0.03, 0.5 +/- 0.05, 0.4 +/- 0.16, 5.3 +/- 0.32, and 5.1 +/- 0.97 nM, respectively. These peptides are highly selective for the NPY Y(1) receptor relative to the NPY Y(2), Y(4), and Y(5) receptors. [D-Arg(25)]-NPY, [D-His(26)]-NPY and Des-AA(11--18)[Cys(7,21), D-Lys(9)(Ac),D-His(26),Pro(34)]-NPY stimulate food intake dose-responsively in Long-Evans rats for at least 4 h after intracerebroventricular administration. Although the involvement of Y(1) receptors in several physiological activities, such as vasoconstriction and anxiolysis, remains to be investigated, adequate tools are now available. PMID:11502885

  14. Potent interleukin 3 receptor agonist with selectively enhanced hematopoietic activity relative to recombinant human interleukin 3.

    PubMed Central

    Thomas, J W; Baum, C M; Hood, W F; Klein, B; Monahan, J B; Paik, K; Staten, N; Abrams, M; McKearn, J P

    1995-01-01

    A systematic evaluation of structure-activity information led to the construction of genetically engineered interleukin 3 (IL-3) receptor agonists (synthokines) with enhanced hematopoietic potency. SC-55494, the most extensively characterized member of this series, exhibits 10- to 20-fold greater biological activity than recombinant human IL-3 (rhIL-3) in human hematopoietic cell proliferation and marrow colony-forming-unit assays. In contrast, SC-55494 is only twice as active as rhIL-3 in priming the synthesis of inflammatory mediators such as leukotriene C4 and triggering the release of histamine from peripheral blood leukocytes. The enhanced hematopoietic activity of SC-55494 correlates with a 60-fold increase in IL-3 alpha-subunit binding affinity and a 20-fold greater affinity for binding to alpha/beta receptor complexes on intact cells relative to rhIL-3. SC-55494 demonstrates a 5- to 10-fold enhanced hematopoietic response relative to its ability to activate the priming and release of inflammatory mediators. Therefore, SC-55494 may ameliorate the myeloablation of cancer therapeutic regimens while minimizing dose-limiting inflammatory side effects. PMID:7537376

  15. The constitutive activity of the adhesion GPCR GPR114/ADGRG5 is mediated by its tethered agonist.

    PubMed

    Wilde, Caroline; Fischer, Liane; Lede, Vera; Kirchberger, Jrgen; Rothemund, Sven; Schneberg, Torsten; Liebscher, Ines

    2016-02-01

    Adhesion GPCRs (aGPCRs) form the second largest, yet most enigmatic class of the GPCR superfamily. Although the physiologic importance of aGPCRs was demonstrated in several studies, the majority of these receptors is still orphan with respect to their agonists and signal transduction. Recent studies reported that aGPCRs are activated through a tethered peptide agonist, coined the Stachel sequence. The Stachel sequence is the most C-terminal part of the highly conserved GPCR autoproteolysis-inducing domain. Here, we used cell culture-based assays to investigate 2 natural splice variants within the Stachel sequence of the orphan Gs coupling aGPCR GPR114/ADGRG5. There is 1 variant constitutively active in cAMP assays (?25-fold over empty vector) and sensitive to mechano-activation. The other variant has low basal activity in cAMP assays (6-fold over empty vector) and is insensitive to mechano-activation. In-depth mutagenesis studies of these functional differences revealed that the N-terminal half of the Stachel sequence confers the agonistic activity, whereas the C-terminal part orientates the agonistic core sequence to the transmembrane domain. Sequence comparison and functional testing suggest that the proposed mechanism of Stachel-mediated activation is relevant not only to GPR114 but to aGPCRs in general.-Wilde, C., Fischer, L., Lede, V., Kirchberger, J., Rothemund, S., Schneberg, T., Liebscher, I. The constitutive activity of the adhesion GPCR GPR114/ADGRG5 is mediated by its tethered agonist. PMID:26499266

  16. Identification of PPARgamma Partial Agonists of Natural Origin (II): In Silico Prediction in Natural Extracts with Known Antidiabetic Activity

    PubMed Central

    Guasch, Laura; Sala, Esther; Mulero, Miquel; Valls, Cristina; Salvadó, Maria Josepa; Pujadas, Gerard; Garcia-Vallvé, Santiago

    2013-01-01

    Background Natural extracts have played an important role in the prevention and treatment of diseases and are important sources for drug discovery. However, to be effectively used in these processes, natural extracts must be characterized through the identification of their active compounds and their modes of action. Methodology/Principal Findings From an initial set of 29,779 natural products that are annotated with their natural source and using a previously developed virtual screening procedure (carefully validated experimentally), we have predicted as potential peroxisome proliferators-activated receptor gamma (PPARγ) partial agonists 12 molecules from 11 extracts known to have antidiabetic activity. Six of these molecules are similar to molecules with described antidiabetic activity but whose mechanism of action is unknown. Therefore, it is plausible that these 12 molecules could be the bioactive molecules responsible, at least in part, for the antidiabetic activity of the extracts containing them. In addition, we have also identified as potential PPARγ partial agonists 10 molecules from 16 plants with undescribed antidiabetic activity but that are related (i.e., they are from the same genus) to plants with known antidiabetic properties. None of the 22 molecules that we predict as PPARγ partial agonists show chemical similarity with a group of 211 known PPARγ partial agonists obtained from the literature. Conclusions/Significance Our results provide a new hypothesis about the active molecules of natural extracts with antidiabetic properties and their mode of action. We also suggest plants with undescribed antidiabetic activity that may contain PPARγ partial agonists. These plants represent a new source of potential antidiabetic extracts. Consequently, our work opens the door to the discovery of new antidiabetic extracts and molecules that can be of use, for instance, in the design of new antidiabetic drugs or functional foods focused towards the prevention/treatment of type 2 Diabetes Mellitus. PMID:23405231

  17. Modulation of agonist-activated calcium influx by extracellular pH in rat pancreatic acini

    SciTech Connect

    Muallem, S.; Pandol, S.J.; Beeker, T.G. )

    1989-12-01

    The biochemical and Ca2+ transport pathways involved in generating the hormone-evoked Ca2+ signal are reported to be influenced by pH. The present study was designed to determine the effect of extracellular pH (pHo) and intracellular pH (pHi) on hormone-stimulated Ca2+ transport. We used rat pancreatic acini and measured free cytosolic Ca2+ concentration ((Ca2+)i) with fura-2, pHi with 2,7-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF), and Ca2+ fluxes with 45Ca2+. In the presence of external Ca2+, increasing pHo increased steady-state (Ca2+)i during sustained agonist stimulation; in the absence of external Ca2+, this increase in (Ca2+)i did not occur. The addition of an antagonist or blocking plasma membrane Ca2+ influx with La3+ in stimulated cells suspended at pHo 8.2 resulted in a reduction in (Ca2+)i. Increasing pHo increased the rate and extent of 45Ca2+ uptake into stimulated cells and the rate and extent of Ca2+ reloading of intracellular stores. The increased Ca2+ content of the intracellular stores with increased pHo indicated that at physiological pHo and pHi the agonist-mobilizable internal stores are not saturated with Ca2+. Changes in pHo affected pHi. However, changes in pHi at constant pHo had no effect on hormone-evoked (Ca2+)i increase, reduction in (Ca2+)i after hormone stimulation, or reloading of intracellular stores. We conclude that the hormone-activated plasma membrane Ca2+ entry pathway responsible for Ca2+ reloading is directly modulated by external H+.

  18. Treatment of experimental autoimmune uveoretinitis with peroxisome proliferator-activated receptor α agonist fenofibrate

    PubMed Central

    Osada, Miho; Kuroyanagi, Kana; Kohno, Hideo; Tsuneoka, Hiroshi

    2014-01-01

    Purpose The peroxisome proliferator-activated receptor α (PPARα) agonist has been approved for treating hypercholesterolemia and lipid abnormalities. Researchers have recently discovered that an anti-inflammatory effect of PPAR agonist may have the potential to treat autoimmune disease. This study aims to investigate the therapeutic effects of fenofibrate on experimental autoimmune uveoretinitis (EAU). Methods EAU was induced in Lewis rats using bovine S-antigen (S-Ag) peptide. Fenofibrate was suspended in 3% arabic gum and administered orally at a high dose of 100 mg/kg and at a low dose of 20 mg/kg every day. Fenofibrate treatment was initiated after the clinical onset once daily for 14 days. The rats were examined every other day for clinical signs of EAU. The histological scores and delayed-type hypersensitivity (DTH) were evaluated on day 28 post-immunization. Morphologic and immunohistochemical examinations were performed with light and confocal microscopy, respectively. Lymphocyte proliferation was measured with [3H] thymidine incorporation into antigen-stimulated T cells from inguinal lymph nodes. Results Clinical and histological scores of EAU were decreased in the fenofibrate-treated groups. The expression of inflammatory cytokines and Müller cell proliferation were inhibited in the fenofibrate-treated groups. DTH was significantly inhibited in the fenofibrate-treated groups, compared with the vehicle-treated groups (controls). Lymphocyte proliferation assay demonstrated decreased proliferation in the presence of 25 mg/ml S-Ag peptide in the fenofibrate-treated groups compared with controls. Conclusions The current results indicate that fenofibrate administered orally following clinical onset has therapeutic effect in EAU. Fenofibrate may be useful for treating intraocular inflammation. PMID:25489225

  19. Agonist activation of arachidonate-regulated Ca2+-selective (ARC) channels in murine parotid and pancreatic acinar cells

    PubMed Central

    Mignen, Olivier; Thompson, Jill L; Yule, David I; Shuttleworth, Trevor J

    2005-01-01

    ARC channels (arachidonate-regulated Ca2+-selective channels) are a novel type of highly Ca2+-selective channel that are specifically activated by low concentrations of agonist-induced arachidonic acid. This activation occurs in the absence of any depletion of internal Ca2+ stores (i.e. they are ‘non-capacitative’). Previous studies in HEK293 cells have shown that these channels provide the predominant pathway for the entry of Ca2+ seen at low agonist concentrations where oscillatory [Ca2+]i signals are typically produced. In contrast, activation of the more widely studied store-operated Ca2+ channels (e.g. CRAC channels) is only seen at higher agonist concentrations where sustained ‘plateau-type’[Ca2+]i responses are observed. We have now demonstrated the presence of ARC channels in both parotid and pancreatic acinar cells and shown that, again, they are specifically activated by the low concentrations of appropriate agonists (carbachol in the parotid, and both carbachol and cholecystokinin in the pancreas) that are associated with oscillatory [Ca2+]i signals in these cells. Uncoupling the receptor-mediated activation of cytosolic phospholipase A2 (cPLA2) with isotetrandrine reduces the activation of the ARC channels by carbachol and, correspondingly, markedly inhibits the [Ca2+]i signals induced by low carbachol concentrations, whilst those signals seen at high agonist concentrations are essentially unaffected. Interestingly, in the pancreatic acinar cells, activation by cholecystokinin induces a current through the ARC channels that is only approximately 60% of that seen with carbachol. This is consistent with previous reports indicating that carbachol-induced [Ca2+]i signals in these cells are much more dependent on Ca2+ entry than are the cholecystokinin-induced responses. PMID:15760932

  20. Identification of novel peroxisome proliferator-activated receptor-gamma (PPARγ) agonists using molecular modeling method.

    PubMed

    Gee, Veronica M W; Wong, Fiona S L; Ramachandran, Lalitha; Sethi, Gautam; Kumar, Alan Prem; Yap, Chun Wei

    2014-11-01

    Peroxisome proliferator-activated receptor-gamma (PPARγ) plays a critical role in lipid and glucose homeostasis. It is the target of many drug discovery studies, because of its role in various disease states including diabetes and cancer. Thiazolidinediones, a synthetic class of agents that work by activation of PPARγ, have been used extensively as insulin-sensitizers for the management of type 2 diabetes. In this study, a combination of QSAR and docking methods were utilised to perform virtual screening of more than 25 million compounds in the ZINC library. The QSAR model was developed using 1,517 compounds and it identified 42,378 potential PPARγ agonists from the ZINC library, and 10,000 of these were selected for docking with PPARγ based on their diversity. Several steps were used to refine the docking results, and finally 30 potentially highly active ligands were identified. Four compounds were subsequently tested for their in vitro activity, and one compound was found to have a K i values of <5 μM. PMID:25168706

  1. Nicotine effects on the activity of mice exposed prenatally to the nicotinic agonist anatoxin-a.

    PubMed

    Macphail, R C; Farmer, J D; Jarema, K A; Chernoff, N

    2005-01-01

    Anatoxin-a is a nicotinic agonist produced by several genera of cyanobacteria, and has caused numerous deaths of wildlife, livestock and domestic animals world-wide. Several studies in the literature have shown that exposure of mice and rats to nicotine early in development alters its effects when the rodents are subsequently challenged with nicotine. We therefore determined the effect of nicotine on the motor activity of adult mice that had been exposed prenatally to anatoxin-a. Pregnant CD-1 mice received either saline vehicle or one of two doses of (+/-) anatoxin-a (125, 200 microg/kg), i.p., on GD13-17. As adults (8 months), control mice of both genders were used to determine the effect of nicotine (0, 0.1, 0.3, 1.0 or 3.0 mg/kg, s.c.) on motor activity measured for 30-min in a photocell device. Under these conditions, nicotine produced dose-related decreases in both horizontal and vertical activity, with an ED50 estimated to be 0.65 mg/kg. Next, additional control mice and mice exposed prenatally to anatoxin-a received the nicotine ED50 and saline vehicle, in a counterbalanced fashion, with one week separating treatments. Nicotine decreased both horizontal and vertical activity in all mice, regardless of prenatal anatoxin-a treatment. Thus, no enduring effects of prenatal anatoxin-a were obtained in adult mice following nicotine challenge. PMID:15975764

  2. Differential pathway coupling efficiency of the activated insulin receptor drives signaling selectivity by xmeta, an allosteric partial agonist antibody

    Technology Transfer Automated Retrieval System (TEKTRAN)

    XMetA, an anti-insulin receptor (IR) monoclonal antibody, is an allosteric partial agonist of the IR. We have previously reported that XMetA activates the “metabolic-biased” Akt kinase signaling pathway while having little or no effect on the “mitogenic” MAPK signaling pathwayof ERK 1/2. To inves...

  3. Endocrine pharmacological characterization of progesterone antagonists and progesterone receptor modulators with respect to PR-agonistic and antagonistic activity.

    PubMed

    Elger, W; Bartley, J; Schneider, B; Kaufmann, G; Schubert, G; Chwalisz, K

    2000-01-01

    Studies were conducted to assess progesterone antagonists (PAs) and progesterone receptor modulators (PRMs) with respect to PR agonistic and antagonistic activities in vivo. These properties are not always adequately reflected in transactivation in vitro models. Studies were performed in pregnant rats, estrogen-primed rabbits (McPhail -Test), and cycling and pregnant guinea pigs. Tested compounds included mifepristone (RU486), onapristone, J867, J956, J1042, and ZK137316. J-compounds induced sub-maximum endometrial transformation and, paradoxically, inhibited effects of progesterone in rabbits. Mifepristone, onapristone, and ZK137316 behaved as 'pure' antagonists in this species. Inhibition of uterine PGF(2alpha) secretion and inhibition of luteolysis in cycling guinea pigs were more sensitive parameters of PR-agonistic and antagonistic properties. 'Pure' PAs inhibited uterine PGF(2alpha) secretion and luteal regression completely. The PR agonist R5020 reversed both effects which demonstrates a PR mediation. Agonistic PRMs (J-substances and mifepristone) showed no or blunted antiluteolytic effects compared to the 'pure' PR antagonist onapristone. When tested in pregnant guinea pigs for their labor-inducing potential, PR agonistic PRMs had much reduced or abolished abortifacient activity compared to mifepristone (mifepristone > J956 > J867/J912 > J1042). However, in cycling animals, superior antiovulatory and antiproliferative properties of the J-substances were seen. Antiovulatory effects of 'pure' and agonistic PRMs are probably due to different mechanisms. The relevance of rodent studies for antiovulatory and uterine antiproliferative effects for the human is still uncertain. The non-abortifacient PRM J1042 induced stromal compaction and inhibition of endometrial proliferation in monkeys, but this effect was not stronger than that of the 'purer' PAs. 'Pure' PAs are important pharmacological tools analogous to PRKO models to study the role of PR in the menstrual cycle and in pregnancy. PMID:11108882

  4. Modulating potency: Physicochemical characteristics are a determining factor of TLR4-agonist nanosuspension activity.

    PubMed

    Dowling, Quinton M; Sivananthan, Sandra J; Guderian, Jeff A; Moutaftsi, Magdalini; Chesko, James D; Fox, Christopher B; Vedvick, Thomas S; Kramer, Ryan M

    2014-03-01

    Activity of adjuvanted vaccines is difficult to predict in vitro and in vivo. The wide compositional and conformational range of formulated adjuvants, from aluminum salts to oil-in-water emulsions, makes comparisons between physicochemical and immunological properties difficult. Even within a formulated adjuvant class, excipient selection and concentration can alter potency and physicochemical properties of the mixture. Complete characterization of physicochemical properties of adjuvanted vaccine formulations and relationship to biological response is necessary to move beyond a guess-and-check paradigm toward directed development. Here we present a careful physicochemical characterization of a two-component nanosuspension containing synthetic TLR-4 agonist glucopyranosyl lipid adjuvant (GLA) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) at various molar ratios. Physicochemical properties were compared with potency, as measured by stimulation of cytokine production in human whole blood. We found a surprising, nonlinear relationship between physicochemical properties and GLA-DPPC ratios that corresponded well with changes in biological activity. We discuss these data in light of the current understanding of TLR4 activation and the conformation-potency relationship in development of adjuvanted vaccines. PMID:24464844

  5. Molecular Determinants of Species-Specific Agonist and Antagonist Activity of A Substituted Flavone towards the Aryl Hydrocarbon Receptor*

    PubMed Central

    Henry, E. C.; Gasiewicz, T. A.

    2008-01-01

    The aryl hydrocarbon receptor (AhR) mediates the toxicity of dioxins and related xenobiotics. Other chemicals also bind the AhR to elicit either agonist or antagonist responses. Here we used site-directed mutagenesis within the ligand binding domain of murine AhR to probe for specific residues that might interact differentially with the antagonist 3’-methoxy-4’-nitroflavone (MNF) compared with the prototypical agonist TCDD. Reduced 3 H-TCDD binding, dioxin-response element (DRE) binding, and transcriptional activity were observed for several point mutants. One mutation, R355I, changed the response to MNF from antagonist to agonist. Notably, Ile is the residue found in the guinea pig AhR, towards which MNF has partial agonist activity in contrast to its strong antagonist activity in mouse. A similar reversal of response to MNF was observed in chimeric AhRs in which the C-terminal region of mAhR was replaced with the guinea pig C-terminal region. These data demonstrate that different amino acids can be important in binding of different AhR ligands and can mediate distinct responses. The ultimate response of the AhR also depends on how other portions of the receptor protein are functionally coupled to the initial ligand binding event. PMID:18294953

  6. [Activity of motorcycle taxi driver: risks and weaknesses self referred].

    PubMed

    da Silva, Mariéli Brum; de Oliveira, Michele Braga; Fontana, Rosane Teresinha

    2011-01-01

    Descriptive research, with qualitative approach, that aimed to identify occupational hazards and weaknesses self-reported by motorcycle drivers. Data were collected in the first half of 2010 through interviews with twelve motorcycle drivers, invited to participate and work on two central points of a municipality in the state of Rio Grande do Sul, Brazil. Data were analyzed using thematic analysis, from which emerged five categories. According to subjects' perception, accidents and assaults represent the greatest risks of the profession. It can be inferred that the actions of health education and disease prevention should be governmental and no governmental strategies that would assign value to the health and safety of these workers. PMID:22664603

  7. Type I IFN-mediated synergistic activation of mouse and human DC subsets by TLR agonists.

    PubMed

    Kreutz, Martin; Bakdash, Ghaith; Dolen, Yusuf; Sköld, Annette E; van Hout-Kuijer, Maaike A; de Vries, I Jolanda M; Figdor, Carl G

    2015-10-01

    Novel approaches of dendritic cell (DC) based cancer immunotherapy aim at harnessing the unique attributes of different DC subsets. Classical monocyte-derived DC vaccines are currently being replaced by either applying primary DCs or specifically targeting antigens and adjuvants to these subsets in vivo. Appropriate DC activation in both strategies is essential for optimal effect. For this purpose TLR agonists are favorable adjuvant choices, with TLR7 triggering being essential for inducing strong Th1 responses. However, mouse CD8α(+) DCs, considered to be the major cross-presenting subset, lack TLR7 expression. Interestingly, this DC subset can respond to TLR7 ligand upon concurrent TLR3 triggering. Nevertheless, the mechanism underlying this synergy remains obscure. We now show that TLR3 ligation results in the production of IFN-α, which rapidly induces the expression of TLR7, resulting in synergistic activation. Moreover, we demonstrate that this mechanism conversely holds for plasmacytoid DCs that respond to TLR3 ligation when TLR7 pathway is mobilized. We further demonstrate that this mechanism of sharpening DC senses is also conserved in human BDCA1(+) DCs and plasmacytoid DCs. These findings have important implications for future clinical trials as it suggests that combinations of TLR ligands should be applied irrespective of initial TLR expression profiles on natural DC subsets for optimal stimulation. PMID:26255864

  8. Human Toll-Like Receptor 8-Selective Agonistic Activities in 1-Alkyl-1H-benzimidazol-2-amines

    PubMed Central

    2015-01-01

    Toll-like receptor (TLR)-8 agonists strongly induce the production of T helper 1-polarizing cytokines and may therefore serve as promising candidate vaccine adjuvants, especially for the very young and the elderly. Earlier structure-based ligand design led to the identification of 3-pentyl-quinoline-2-amine as a novel, human TLR8-specific agonist. Comprehensive structure–activity relationships in ring-contracted 1-alkyl-1H-benzimidazol-2-amines were undertaken, and the best-in-class compound, 4-methyl-1-pentyl-1H-benzo[d]imidazol-2-amine, was found to be a pure TLR8 agonist, evoking strong proinflammatory cytokine and Type II interferon responses in human PBMCs, with no attendant CD69 upregulation in natural lymphocytic subsets. The 1-alkyl-1H-benzimidazol-2-amines represent a novel, alternate chemotype with pure TLR8-agonistic activities and will likely prove useful not only in understanding TLR8 signaling but also perhaps as a candidate vaccine adjuvant. PMID:25102141

  9. The glucagon-like peptide 1 receptor agonist enhances intrinsic peroxisome proliferator-activated receptor γ activity in endothelial cells

    SciTech Connect

    Onuma, Hirohisa; Inukai, Kouichi Kitahara, Atsuko; Moriya, Rie; Nishida, Susumu; Tanaka, Toshiaki; Katsuta, Hidenori; Takahashi, Kazuto; Sumitani, Yoshikazu; Hosaka, Toshio; Ishida, Hitoshi

    2014-08-22

    Highlights: • PPARγ activation was involved in the GLP-1-mediated anti-inflammatory action. • Exendin-4 enhanced endogenous PPARγ transcriptional activity in HUVECs. • H89, a PKA inhibitor, abolished GLP-1-induced PPARγ enhancement. • The anti-inflammatory effects of GLP-1 may be explained by PPARγ activation. - Abstract: Recent studies have suggested glucagon-like peptide-1 (GLP-1) signaling to exert anti-inflammatory effects on endothelial cells, although the precise underlying mechanism remains to be elucidated. In the present study, we investigated whether PPARγ activation is involved in the GLP-1-mediated anti-inflammatory action on endothelial cells. When we treated HUVEC cells with 0.2 ng/ml exendin-4, a GLP-1 receptor agonist, endogenous PPARγ transcriptional activity was significantly elevated, by approximately 20%, as compared with control cells. The maximum PPARγ activity enhancing effect of exendin-4 was observed 12 h after the initiation of incubation with exendin-4. As H89, a PKA inhibitor, abolished GLP-1-induced PPARγ enhancement, the signaling downstream from GLP-1 cross-talk must have been involved in PPARγ activation. In conclusion, our results suggest that GLP-1 has the potential to induce PPARγ activity, partially explaining the anti-inflammatory effects of GLP-1 on endothelial cells. Cross-talk between GLP-1 signaling and PPARγ activation would have major impacts on treatments for patients at high risk for cardiovascular disease.

  10. Direct and Indirect 5-HT receptor agonists produce gender-specific effects on locomotor and vertical activity in C57 BL/6J mice

    PubMed Central

    Brookshire, Bethany R.; Jones, Sara R.

    2009-01-01

    It is well established that the dopamine (DA) and serotonin (5-HT) systems have extensive and complex interactions. However, the effects of specific 5-HT receptor agonists on traditionally DA-related behaviors remain unclear. Our goal in these studies was to characterize the effects of 5-HT receptor agonists on measures of locomotor activity and vertical rearing. The SSRIs fluoxetine and citalopram produced significant decreases in locomotor activity and vertical rearing at the highest doses used with females significant more sensitive to citalopram. The 5-HT1A agonist 8-OH-DPAT and the 5-HT2C agonist MK 212 significantly decreased activity in both male and female mice, with females more sensitive to 8-OH-DPAT. In contrast, the 5-HT1B agonist RU 24969 and the 5-HT2A agonist DOI both increased activity, with DOI exhibiting differential effects with regard to sex. Finally, the 5-HT3 agonist SR 57227 produced significant locomotor increases only in female mice at the lowest dose. The results of these experiments define locomotor profiles of several 5-HT agonists in male and female C57BL/6J mice, providing a foundation for further explorations of 5-HT receptor effects on activity. PMID:19698737

  11. Potential output pathways for agonistic-like responses resulting from the GABA(A) blockade of the torus semicircularis dorsalis in weakly electric fish, Gymnotus carapo.

    PubMed

    Teixeira Duarte, Terence; Hoffmann, Anette; de Souza Fim Pereira, Aparecida; Aparecida Lopes Corrêa, Sônia

    2006-05-30

    The purpose of this study is to examine the pathways involved in the electromotor (electric organ discharge interruptions) and skeletomotor responses (defense-like) observed by blockade of GABAergic control of the torus semicircularis dorsalis (TSd) of the awake weakly electric fish Gymnotus carapo, described in a former study. Microinjection of NMDA (5 mM) into the pacemaker nucleus (PM) through a guide cannula previously implanted caused a prolonged interruption of the electric organ discharge (EOD) intermingled with reduction in frequency, similar to that described for TSd GABA(A) blockade, but without noticeable skeletomotor effects. The EOD alterations elicited by bicuculline microinjections (0.245 mM) into the TSd could be blocked or attenuated by a previous microinjection of AP-5 (0.5 mM), an NMDA antagonist, into the PM. Labeled terminals are found in the nucleus electrosensorius (nE) after injection of the biotinylated dextran amine (BDA) tracer into the TSd and into the sublemniscal prepacemaker nucleus (SPPn) subsequent to the tracer injection into the nE. Defense-like responses but not EOD interruptions are observed after microinjections of NMDA (5 mM) into the rhombencephalic reticular formation (RF), where labeled terminals are seen after BDA injection into the TSd and somata are filled after injection of the tracer into the spinal cord. In this last structure, marked fibers are seen subsequent to injection of BDA into the RF. These results suggest that two distinct pathways originate from the torus: one for EOD control, reaching PM through nE and SPPn, and the other one for skeletomotor control reaching premotor reticular neurons. Both paths could be activated by toral GABA(A) blockade. PMID:16696952

  12. Rational design of orally-active, pyrrolidine-based progesterone receptor partial agonists

    SciTech Connect

    Thompson, Scott K.; Washburn, David G.; Frazee, James S.; Madauss, Kevin P.; Hoang, Tram H.; Lapinski, Leahann; Grygielko, Eugene T.; Glace, Lindsay E.; Trizna, Walter; Williams, Shawn P.; Duraiswami, Chaya; Bray, Jeffrey D.; Laping, Nicholas J.

    2010-09-03

    Using the X-ray crystal structure of an amide-based progesterone receptor (PR) partial agonist bound to the PR ligand binding domain, a novel PR partial agonist class containing a pyrrolidine ring was designed. Members of this class of N-alkylpyrrolidines demonstrate potent and highly selective partial agonism of the progesterone receptor, and one of these analogs was shown to be efficacious upon oral dosing in the OVX rat model of estrogen opposition.

  13. A novel natural Nrf2 activator with PPARγ-agonist (monascin) attenuates the toxicity of methylglyoxal and hyperglycemia

    SciTech Connect

    Hsu, Wei-Hsuan; Lee, Bao-Hong; Chang, Yu-Ying; Hsu, Ya-Wen; Pan, Tzu-Ming

    2013-11-01

    Methylglyoxal (MG) is a toxic-glucose metabolite and a major precursor of advanced glycation endproducts (AGEs). MG has been reported to result in inflammation by activating receptor for AGEs (RAGE). We recently found that Monascus-fermented metabolite monascin acts as a novel natural peroxisome proliferator-activated receptor-γ (PPARγ) agonist that improves insulin sensitivity. We investigated the metabolic, biochemical, and molecular abnormalities characteristic of type 2 diabetes in MG-treated Wistar rats treated with oral administration of monascin or rosiglitazone. Monascin (a novel PPARγ agonist) activated nuclear factor-erythroid 2-related factor 2 (Nrf2) and down-regulated hyperinsulinmia in oral glucose tolerance test (OGTT). Monascin was able to elevate glyoxalase-1 expression via activation of hepatic Nrf2, hence, resulting in MG metabolism to D-lactic acid and protected from AGEs production in MG-treated rats. Rosiglitazone did not activate Nrf2 nor glyoxalase expression to lower serum and hepatic AGEs levels. Monascin acts as a novel natural Nrf2 activator with PPARγ-agonist activity were confirmed by Nrf2 and PPARγ reporter assays in Hep G2 cells. These findings suggest that monascin acts as an anti-diabetic and anti-oxidative stress agent to a greater degree than rosiglitazone and thus may have therapeutic potential for the prevention of diabetes. - Highlights: • Monascin acts as a PPARgamma agonist. • Monascin activates Nrf2 and AMPK. • Monascin promotes MG metabolism into D-lactic acid. • Monascin attenuates inflammation and diabetes in vivo.

  14. Non-conventional synchronization of weakly coupled active oscillators

    NASA Astrophysics Data System (ADS)

    Manevitch, L. I.; Kovaleva, M. A.; Pilipchuk, V. N.

    2013-03-01

    We present a new type of self-sustained vibrations in the fundamental physical model covering a broad area of applications from wave generation in radiophysics and nonlinear optics to the heart muscle contraction and eyesight disorder in biophysics. Such a diversity of applications is due to the universal physical phenomenon of synchronization. Previous studies of this phenomenon, originating from Huygens famous observation, are based mainly on the model of two weakly coupled Van der Pol oscillators and usually deal with their synchronization in the regimes close to nonlinear normal modes (NNMs). In this work, we show for the first time that, in the important case of threshold excitation, an alternative synchronization mechanism can develop when the conventional synchronization becomes impossible. We identify this mechanism as an appearance of dynamic attractor with the complete periodic energy exchange between the oscillators, which is the dissipative analogue of highly intensive beats in a conservative system. This type of motion is therefore opposite to the NNM-type synchronization with no energy exchange by definition. The analytical description of these vibrations employs the concept of Limiting Phase Trajectories (LPTs) introduced by one of the authors earlier for conservative systems. Finally, within the LPT approach, we describe the transition from the complete energy exchange between the oscillators to the energy localization mostly on one of the two oscillators. The localized mode is an attractor in the range of model parameters wherein the LPT as well as the in-phase and out-of-phase NNMs become unstable.

  15. The PPARalpha Agonist Fenofibrate Preserves Hippocampal Neurogenesis and Inhibits Microglial Activation After Whole-Brain Irradiation

    SciTech Connect

    Ramanan, Sriram; Kooshki, Mitra; Zhao Weiling; Hsu, F.-C.; Riddle, David R.; Robbins, Mike E.

    2009-11-01

    Purpose: Whole-brain irradiation (WBI) leads to cognitive impairment months to years after radiation. Numerous studies suggest that decreased hippocampal neurogenesis and microglial activation are involved in the pathogenesis of WBI-induced brain injury. The goal of this study was to investigate whether administration of the peroxisomal proliferator-activated receptor (PPAR) alpha agonist fenofibrate would prevent the detrimental effect of WBI on hippocampal neurogenesis. Methods and Materials: For this study, 129S1/SvImJ wild-type and PPARalpha knockout mice that were fed either regular or 0.2% wt/wt fenofibrate-containing chow received either sham irradiation or WBI (10-Gy single dose of {sup 137}Cs gamma-rays). Mice were injected intraperitoneally with bromodeoxyuridine to label the surviving cells at 1 month after WBI, and the newborn neurons were counted at 2 months after WBI by use of bromodeoxyuridine/neuronal nuclei double immunofluorescence. Proliferation in the subgranular zone and microglial activation were measured at 1 week and 2 months after WBI by use of Ki-67 and CD68 immunohistochemistry, respectively. Results: Whole-brain irradiation led to a significant decrease in the number of newborn hippocampal neurons 2 months after it was performed. Fenofibrate prevented this decrease by promoting the survival of newborn cells in the dentate gyrus. In addition, fenofibrate treatment was associated with decreased microglial activation in the dentate gyrus after WBI. The neuroprotective effects of fenofibrate were abolished in the knockout mice, indicating a PPARalpha-dependent mechanism or mechanisms. Conclusions: These data highlight a novel role for PPARalpha ligands in improving neurogenesis after WBI and offer the promise of improving the quality of life for brain cancer patients receiving radiotherapy.

  16. Characterization of AhR agonists reveals antagonistic activity in European herring gull (Larus argentatus) eggs.

    PubMed

    Muusse, Martine; Christensen, Guttorm; Gomes, Tânia; Kočan, Anton; Langford, Katherine; Tollefsen, Knut Erik; Vaňková, Lenka; Thomas, Kevin V

    2015-05-01

    European herring gull (Larus argentatus) eggs from two Norwegian islands, Musvær in the south east and Reiaren in Northern Norway, were screened for dioxins, furans, and dioxin-like and selected non-dioxin-like polychlorinated biphenyls (PCBs), and subjected to non-target analysis to try to identify the aryl hydrocarbon receptor (AhR) agonists, responsible for elevated levels measured using the dioxin responsive chemically activated luciferase expression (DR-CALUX) assay. Eggs from Musvær contained chemically calculated toxic equivalent (WHO TEQ) levels of between 109 and 483 pg TEQ/g lw, and between 82 and 337 pg TEQ/g lw was determined in eggs from Reiaren. In particular PCB126 contributed highly to the total TEQ (69-82%). In 19 of the 23 samples the calculated WHO TEQ was higher than the TEQCALUX. Using CALUX specific relative effect potencies (REPs), the levels were lower at between 77 and 292 pg/g lw in eggs from Musvær and between 55 and 223 pg/g lw in eggs from Reiaren, which was higher than the TEQCALUX in 16 of the 23 samples. However, the means of the REP values and the TEQCALUX were not significantly different. This suggests the presence of compounds that can elicit antagonist effects, with a low binding affinity to the AhR. Non-target analysis identified the presence of hexachlorobenzene (HCB) (quantified at 9.6-185 pg/g lw) but neither this compound nor high concentrations of PCB126 and non-dioxin-like PCBs could explain the differences between the calculated TEQ or REP values and the TEQCALUX. Even though, for most AhR agonists, the sensitivity of herring gulls is not known, the reported levels can be considered to represent a risk for biological effects in the developing embryo, compared to LC50 values in chicken embryos. For human consumers of herring gull eggs, these eggs contain TEQ levels up to four times higher than the maximum tolerable weekly intake. PMID:25666281

  17. TLR3 agonist and Sorafenib combinatorial therapy promotes immune activation and controls hepatocellular carcinoma progression

    PubMed Central

    Ho, Victor; Lim, Tong Seng; Lee, Justin; Steinberg, Jeffrey; Szmyd, Radoslaw; Tham, Muly; Yaligar, Jadegoud; Kaldis, Philipp; Abastado, Jean-Pierre; Chew, Valerie

    2015-01-01

    Hepatocellular carcinoma (HCC) is associated with high mortality and the current therapy for advanced HCC, Sorafenib, offers limited survival benefits. Here we assessed whether combining the TLR3 agonist: lysine-stabilized polyinosinic-polycytidylic-acid (poly-ICLC) with Sorafenib could enhance tumor control in HCC. Combinatorial therapy with poly-ICLC and Sorafenib increased apoptosis and reduced proliferation of HCC cell lines in vitro, in association with impaired phosphorylation of AKT, MEK and ERK. In vivo, the combinatorial treatment enhanced control of tumor growth in two mouse models: one transplanted with Hepa 1-6 cells, and the other with liver tumors induced using the Sleeping beauty transposon. Tumor cell apoptosis and host immune responses in the tumor microenvironment were enhanced. Particularly, the activation of local NK cells, T cells, macrophages and dendritic cells was enhanced. Decreased expression of the inhibitory signaling molecules PD-1 and PD-L1 was observed in tumor-infiltrating CD8+ T cells and tumor cells, respectively. Tumor infiltration by monocytic-myeloid derived suppressor cells (Mo-MDSC) was also reduced indicating the reversion of the immunosuppressive tumor microenvironment. Our data demonstrated that the combinatorial therapy with poly-ICLC and Sorafenib enhances tumor control and local immune response hence providing a rationale for future clinical studies. PMID:26287667

  18. Selective serotonin 5-HT1A receptor biased agonists elicitdistinct brain activation patterns: a pharmacoMRI study.

    PubMed

    Becker, G; Bolbos, R; Costes, N; Redouté, J; Newman-Tancredi, A; Zimmer, L

    2016-01-01

    Serotonin 1A (5-HT1A) receptors are involved in several physiological and pathological processes and constitute therefore an important therapeutic target. The recent pharmacological concept of biased agonism asserts that highly selective agonists can preferentially direct receptor signaling to specific intracellular responses, opening the possibility of drugs targeting a receptor subtype in specific brain regions. The present study brings additional support to this concept thanks to functional magnetic resonance imaging (7 Tesla-fMRI) in anaesthetized rats. Three 5-HT1A receptor agonists (8-OH-DPAT, F13714 and F15599) and one 5-HT1A receptor antagonist (MPPF) were compared in terms of influence on the brain blood oxygen level-dependent (BOLD) signal. Our study revealed for the first time contrasting BOLD signal patterns of biased agonists in comparison to a classical agonist and a silent antagonist. By providing functional information on the influence of pharmacological activation of 5-HT1A receptors in specific brain regions, this neuroimaging approach, translatable to the clinic, promises to be useful in exploring the new concept of biased agonism in neuropsychopharmacology. PMID:27211078

  19. Peroxisome proliferator-activated receptor-γ agonists repress epithelial sodium channel expression in the kidney

    PubMed Central

    Borsting, Emily; Cheng, Vicki Pei-Chun; Glass, Chris K.; Vallon, Volker

    2012-01-01

    Thiazolidinediones (TZDs), known as peroxisome proliferator-activated receptor (PPAR) agonists, are used to treat type 2 diabetes. However, ∼5% of patients experience the treatment-limiting side effect of edema. Studies have implicated activation of the epithelial sodium channel (ENaC) as a cause of TZD-induced fluid retention, although there have been conflicting reports. The goal of this study was to resolve the role of PPARγ in control of ENaC isoforms in the kidney. Herein, we demonstrate in mice that rosiglitazone (RGZ), a PPARγ ligand, increases body weight and abdominal fat pad fluid content and reduces hematocrit. Seven days of RGZ decreases ENaCα and ENaCβ mRNA and ENaCγ protein expression in the kidney cortex, and acute treatment for 5 h with pioglitazone, another potent TZD, does not increase renal ENaC isoform mRNA or protein expression. Pioglitazone also decreases ENaCα and ENaCγ mRNA expression in a cortical collecting duct cell line. As no direct transcriptional studies had been conducted, we examined the PPARγ-dependent regulation of ENaC. Pioglitazone represses ENaCγ promoter activity, and this repression is partially relieved by inhibition of protein synthesis. Chromatin immunoprecipitation assays revealed that repression is associated with a decrease in histone H4K5 acetylation at the proximal ENaCγ promoter. In summary, TZDs do not increase ENaC mRNA expression in the kidney, and in fact repress the ENaCγ promoter via an indirect transcriptional mechanism. PMID:22169011

  20. Evidence for Noncanonical Neurotransmitter Activation: Norepinephrine as a Dopamine D2-Like Receptor Agonist.

    PubMed

    Sánchez-Soto, Marta; Bonifazi, Alessandro; Cai, Ning Sheng; Ellenberger, Michael P; Newman, Amy Hauck; Ferré, Sergi; Yano, Hideaki

    2016-04-01

    The Gαi/o-coupled dopamine D2-like receptor family comprises three subtypes: the D2 receptor (D2R), with short and long isoform variants (D2SR and D2LR), D3 receptor (D3R), and D4 receptor (D4R), with several polymorphic variants. The common overlap of norepinephrine innervation and D2-like receptor expression patterns prompts the question of a possible noncanonical action by norepinephrine. In fact, previous studies have suggested that norepinephrine can functionally interact with D4R. To our knowledge, significant interactions between norepinephrine and D2R or D3R receptors have not been demonstrated. By using radioligand binding and bioluminescent resonance energy transfer (BRET) assays in transfected cells, the present study attempted a careful comparison between dopamine and norepinephrine in their possible activation of all D2-like receptors, including the two D2R isoforms and the most common D4R polymorphic variants. Functional BRET assays included activation of G proteins with all Gαi/o subunits, adenylyl cyclase inhibition, and β arrestin recruitment. Norepinephrine acted as a potent agonist for all D2-like receptor subtypes, with the general rank order of potency of D3R > D4R ≥ D2SR ≥ D2L. However, for both dopamine and norepinephrine, differences depended on the Gαi/o protein subunit involved. The most striking differences were observed with Gαi2, where the rank order of potencies for both dopamine and norepinephrine were D4R > D2SR = D2LR > D3R. Furthermore the results do not support the existence of differences in the ability of dopamine and norepinephrine to activate different human D4R variants. The potency of norepinephrine for adrenergic α2A receptor was only about 20-fold higher compared with D3R and D4R across the three functional assays. PMID:26843180

  1. Evidence for Noncanonical Neurotransmitter Activation: Norepinephrine as a Dopamine D2-Like Receptor Agonist

    PubMed Central

    Sánchez-Soto, Marta; Bonifazi, Alessandro; Cai, Ning Sheng; Ellenberger, Michael P.; Newman, Amy Hauck

    2016-01-01

    The Gαi/o-coupled dopamine D2-like receptor family comprises three subtypes: the D2 receptor (D2R), with short and long isoform variants (D2SR and D2LR), D3 receptor (D3R), and D4 receptor (D4R), with several polymorphic variants. The common overlap of norepinephrine innervation and D2-like receptor expression patterns prompts the question of a possible noncanonical action by norepinephrine. In fact, previous studies have suggested that norepinephrine can functionally interact with D4R. To our knowledge, significant interactions between norepinephrine and D2R or D3R receptors have not been demonstrated. By using radioligand binding and bioluminescent resonance energy transfer (BRET) assays in transfected cells, the present study attempted a careful comparison between dopamine and norepinephrine in their possible activation of all D2-like receptors, including the two D2R isoforms and the most common D4R polymorphic variants. Functional BRET assays included activation of G proteins with all Gαi/o subunits, adenylyl cyclase inhibition, and β arrestin recruitment. Norepinephrine acted as a potent agonist for all D2-like receptor subtypes, with the general rank order of potency of D3R > D4R ≥ D2SR ≥ D2L. However, for both dopamine and norepinephrine, differences depended on the Gαi/o protein subunit involved. The most striking differences were observed with Gαi2, where the rank order of potencies for both dopamine and norepinephrine were D4R > D2SR = D2LR >> D3R. Furthermore the results do not support the existence of differences in the ability of dopamine and norepinephrine to activate different human D4R variants. The potency of norepinephrine for adrenergic α2A receptor was only about 20-fold higher compared with D3R and D4R across the three functional assays. PMID:26843180

  2. Polyacetylenes from Notopterygium incisum–New Selective Partial Agonists of Peroxisome Proliferator-Activated Receptor-Gamma

    PubMed Central

    Liu, Xin; Noha, Stefan M.; Malainer, Clemens; Kramer, Matthias P.; Cocic, Amina; Kunert, Olaf; Schinkovitz, Andreas; Heiss, Elke H.; Schuster, Daniela

    2013-01-01

    Peroxisome proliferator-activated receptor gamma (PPARγ) is a key regulator of glucose and lipid metabolism and therefore an important pharmacological target to combat metabolic diseases. Since the currently used full PPARγ agonists display serious side effects, identification of novel ligands, particularly partial agonists, is highly relevant. Searching for new active compounds, we investigated extracts of the underground parts of Notopterygium incisum, a medicinal plant used in traditional Chinese medicine, and observed significant PPARγ activation using a PPARγ-driven luciferase reporter model. Activity-guided fractionation of the dichloromethane extract led to the isolation of six polyacetylenes, which displayed properties of selective partial PPARγ agonists in the luciferase reporter model. Since PPARγ activation by this class of compounds has so far not been reported, we have chosen the prototypical polyacetylene falcarindiol for further investigation. The effect of falcarindiol (10 µM) in the luciferase reporter model was blocked upon co-treatment with the PPARγ antagonist T0070907 (1 µM). Falcarindiol bound to the purified human PPARγ receptor with a Ki of 3.07 µM. In silico docking studies suggested a binding mode within the ligand binding site, where hydrogen bonds to Cys285 and Glu295 are predicted to be formed in addition to extensive hydrophobic interactions. Furthermore, falcarindiol further induced 3T3-L1 preadipocyte differentiation and enhanced the insulin-induced glucose uptake in differentiated 3T3-L1 adipocytes confirming effectiveness in cell models with endogenous PPARγ expression. In conclusion, we identified falcarindiol-type polyacetylenes as a novel class of natural partial PPARγ agonists, having potential to be further explored as pharmaceutical leads or dietary supplements. PMID:23630612

  3. Development of a Peptide-Derived Orally-Active Kappa-Opioid Receptor Agonist Targeting Peripheral Pain

    PubMed Central

    Hughes, Jr, Francis M.; Shaner, Brooke E.; Brower, Justin O.; Woods, R. Jeremy; Dix, Thomas A.

    2013-01-01

    Kappa-opioid agonists are particularly efficacious in the treatment of peripheral pain but suffer from central nervous system (CNS)-mediated effects that limit their development. One promising kappa-agonist is the peptidic compound CR665. Although not orally available, CR665 given i.v. exhibits high peripheral to CNS selectivity and benefits patients with visceral and neuropathic pain. In this study we have generated a series of derivatives of CR665 and screened them for oral activity in the acetic acid-induced rat writhing assay for peripheral pain. Five compounds were further screened for specificity of activation of kappa receptors as well as agonism and antagonism at mu and delta receptors, which can lead to off-target effects. All active derivatives engaged the kappa receptor with EC50s in the low nM range while agonist selectivity for kappa over mu or delta was >11,000-200,000-fold. No antagonist activity was detected. One compound was chosen for further analysis (Compound 9). An oral dose response of 9 in rats yielded an EC50 of 4.7 mg/kg, approaching a druggable level for an oral analgesic. To assess the peripheral selectivity of this compound an i.v. dose response in rats was assessed in the writhing assay and hotplate assay (an assay of CNS-mediated pain). The EC50 in the writhing assay was 0.032 mg/kg while no activity was detectable in the hotplate assay at doses as high as 30 mg/kg, indicating a peripheral selectivity of >900-fold. We propose that compound 9 is a candidate for development as an orally-available peripherally-restricted kappa agonist. PMID:24222801

  4. Cerebral radioprotection by pentobarbital: Dose-response characteristics and association with GABA agonist activity

    SciTech Connect

    Olson, J.J.; Friedman, R.; Orr, K.; Delaney, T.; Oldfield, E.H. )

    1990-05-01

    Pentobarbital reduces cerebral radiation toxicity; however, the mechanism of this phenomenon remains unknown. As an anesthetic and depressant of cerebral metabolism, pentobarbital induces its effects on the central nervous system by stimulating the binding of gamma-aminobutyric acid (GABA) to its receptor and by inhibiting postsynaptic excitatory amino acid activity. The purpose of this study is to investigate the role of these actions as well as other aspects of the radioprotective activity of pentobarbital. Fischer 344 rats were separated into multiple groups and underwent two dose-response evaluations. In one set of experiments to examine the relationship of radioprotection to pentobarbital dose, a range of pentobarbital doses (0 to 75 mg/kg) were given intraperitoneally prior to a constant-level radiation dose (70 Gy). In a second series of experiments to determine the dose-response relationship of radiation protection to radiation dose, a range of radiation doses (10 to 90 Gy) were given with a single pentobarbital dose. Further groups of animals were used to evaluate the importance of the timing of pentobarbital administration, the function of the (+) and (-) isomers of pentobarbital, and the role of an alternative GABA agonist (diazepam). In addition, the potential protective effects of alternative methods of anesthesia (ketamine) and induction of cerebral hypometabolism (hypothermia) were examined. Enhancement of survival time from acute radiation injury due to high-dose single-fraction whole-brain irradiation was maximal with 60 mg/kg of pentobarbital, and occurred over the range of all doses examined between 30 to 90 Gy. Protection was seen only in animals that received the pentobarbital before irradiation. Administration of other compounds that enhance GABA binding (Saffan and diazepam) also significantly enhanced survival time.

  5. 6alpha-ethyl-chenodeoxycholic acid (6-ECDCA), a potent and selective FXR agonist endowed with anticholestatic activity.

    PubMed

    Pellicciari, Roberto; Fiorucci, Stefano; Camaioni, Emidio; Clerici, Carlo; Costantino, Gabriele; Maloney, Patrick R; Morelli, Antonio; Parks, Derek J; Willson, Timothy M

    2002-08-15

    A series of 6alpha-alkyl-substituted analogues of chenodeoxycholic acid (CDCA) were synthesized and evaluated as potential farnesoid X receptor (FXR) ligands. Among them, 6alpha-ethyl-chenodeoxycholic acid (6-ECDCA) was shown to be a very potent and selective FXR agonist (EC(50) = 99 nM) and to be endowed with anticholeretic activity in an in vivo rat model of cholestasis. PMID:12166927

  6. Design and Synthesis of Sulfamoyl Benzoic Acid Analogues with Subnanomolar Agonist Activity Specific to the LPA2 Receptor

    PubMed Central

    2015-01-01

    Lysophosphatidic acid (LPA) is a growth factor-like mediator and a ligand for multiple GPCR. The LPA2 GPCR mediates antiapoptotic and mucosal barrier-protective effects in the gut. We synthesized sulfamoyl benzoic acid (SBA) analogues that are the first specific agonists of LPA2, some with subnanomolar activity. We developed an experimental SAR that is supported and rationalized by computational docking analysis of the SBA compounds into the LPA2 ligand-binding pocket. PMID:25100502

  7. Active Region Filaments Might Harbor Weak Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Díaz Baso, C. J.; Martínez González, M. J.; Asensio Ramos, A.

    2016-05-01

    Recent spectropolarimetric observations of active region filaments have revealed polarization profiles with signatures typical of the strong field Zeeman regime. The conspicuous absence in those observations of scattering polarization and Hanle effect signatures was then pointed out by some authors. This was interpreted as either a signature of mixed “turbulent” field components or as a result of optical thickness. In this article, we present a natural scenario to explain these Zeeman-only spectropolarimetric observations of active region (AR) filaments. We propose a two-component model, one on top of the other. Both components have horizontal fields, with the azimuth difference between them being close to 90°. The component that lies lower in the atmosphere is permeated by a strong field of the order of 600 G, while the upper component has much weaker fields, of the order of 10 G. The ensuing scattering polarization signatures of the individual components have opposite signs, so its combination along the line of sight reduces—and even can cancel out—the Hanle signatures, giving rise to an apparent Zeeman-only profile. This model is also applicable to other chromospheric structures seen in absorption above ARs.

  8. GPR40 agonist ameliorates liver X receptor-induced lipid accumulation in liver by activating AMPK pathway

    PubMed Central

    Li, Meng; Meng, Xiangyu; Xu, Jie; Huang, Xiuqing; Li, Hongxia; Li, Guoping; Wang, Shu; Man, Yong; Tang, Weiqing; Li, Jian

    2016-01-01

    Hepatic steatosis is strongly linked to insulin resistance and type 2 diabetes. GPR40 is a G protein-coupled receptor mediating free fatty acid-induced insulin secretion and thus plays a beneficial role in the improvement of diabetes. However, the impact of GPR40 agonist on hepatic steatosis still remains to be elucidated. In the present study, we found that activation of GPR40 by its agonist GW9508 attenuated Liver X receptor (LXR)-induced hepatic lipid accumulation. Activation of LXR in the livers of C57BL/6 mice fed a high-cholesterol diet and in HepG2 cells stimulated by chemical agonist caused increased expression of its target lipogenic genes and subsequent lipid accumulation. All these effects of LXR were dramatically downregulated after GW9508 supplementation. Moreover, GPR40 activation was accompanied by upregulation of AMPK pathway, whereas the inhibitive effect of GPR40 on the lipogenic gene expression was largely abrogated by AMPK knockdown. Taken together, our results demonstrated that GW9508 exerts a beneficial effect to ameliorate LXR-induced hepatic steatosis through regulation of AMPK signaling pathway. PMID:27121981

  9. GPR40 agonist ameliorates liver X receptor-induced lipid accumulation in liver by activating AMPK pathway.

    PubMed

    Li, Meng; Meng, Xiangyu; Xu, Jie; Huang, Xiuqing; Li, Hongxia; Li, Guoping; Wang, Shu; Man, Yong; Tang, Weiqing; Li, Jian

    2016-01-01

    Hepatic steatosis is strongly linked to insulin resistance and type 2 diabetes. GPR40 is a G protein-coupled receptor mediating free fatty acid-induced insulin secretion and thus plays a beneficial role in the improvement of diabetes. However, the impact of GPR40 agonist on hepatic steatosis still remains to be elucidated. In the present study, we found that activation of GPR40 by its agonist GW9508 attenuated Liver X receptor (LXR)-induced hepatic lipid accumulation. Activation of LXR in the livers of C57BL/6 mice fed a high-cholesterol diet and in HepG2 cells stimulated by chemical agonist caused increased expression of its target lipogenic genes and subsequent lipid accumulation. All these effects of LXR were dramatically downregulated after GW9508 supplementation. Moreover, GPR40 activation was accompanied by upregulation of AMPK pathway, whereas the inhibitive effect of GPR40 on the lipogenic gene expression was largely abrogated by AMPK knockdown. Taken together, our results demonstrated that GW9508 exerts a beneficial effect to ameliorate LXR-induced hepatic steatosis through regulation of AMPK signaling pathway. PMID:27121981

  10. Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone attenuates postincisional pain by regulating macrophage polarization

    SciTech Connect

    Hasegawa-Moriyama, Maiko; Ohnou, Tetsuya; Godai, Kohei; Kurimoto, Tae; Nakama, Mayo; Kanmura, Yuichi

    2012-09-14

    Highlights: Black-Right-Pointing-Pointer Rosiglitazone attenuated postincisional pain. Black-Right-Pointing-Pointer Rosiglitazone alters macrophage polarization to F4/80{sup +}CD206{sup +} M2 macrophages at the incisional sites. Black-Right-Pointing-Pointer Transplantation of rosiglitazone-treated macrophages produced analgesic effects. -- Abstract: Acute inflammation triggered by macrophage infiltration to injured tissue promotes wound repair and may induce pain hypersensitivity. Peroxisome proliferator-activated receptor {gamma} (PPAR){gamma} signaling is known to regulate heterogeneity of macrophages, which are often referred to as classically activated (M1) and alternatively activated (M2) macrophages. M1 macrophages have considerable antimicrobial activity and produce a wide variety of proinflammatory cytokines. In contrast, M2 macrophages are involved in anti-inflammatory and homeostatic functions linked to wound healing and tissue repair. Although it has been suggested that PPAR{gamma} agonists attenuate pain hypersensitivity, the molecular mechanism of macrophage-mediated effects of PPAR{gamma} signaling on pain development has not been explored. In this study, we investigated the link between the phenotype switching of macrophage polarization induced by PPAR{gamma} signaling and the development of acute pain hypersensitivity. Local administration of rosiglitazone significantly ameliorated hypersensitivity to heat and mechanical stimuli, and paw swelling. Consistent with the down-regulation of nuclear factor {kappa}B (NF{kappa}B) phosphorylation by rosiglitazone at the incisional sites, the number of F4/80{sup +}iNOS{sup +} M1 macrophages was decreased whereas numbers of F4/80{sup +}CD206{sup +} M2 macrophages were increased in rosiglitazone-treated incisional sites 24 h after the procedure. In addition, gene induction of anti-inflammatory M2-macrophage-associated markers such as arginase1, FIZZ1 and interleukin (IL)-10 were significantly increased, whereas M1-macrophage-related molecules such as integrin {alpha}X, IL-1{beta}, MIP2{alpha} and leptin were decreased at rosiglitazone-treated incisional sites. Moreover, transplantation of rosiglitazone-treated peritoneal macrophages into the incisional sites significantly attenuated hyperalgesia. We speculate that local administration of rosiglitazone significantly alleviated the development of postincisional pain, possibly through regulating macrophage polarity at the inflamed site. PPAR{gamma} signaling in macrophages may be a potential therapeutic target for the treatment of acute pain development.

  11. The transcriptional PPARβ/δ network in human macrophages defines a unique agonist-induced activation state

    PubMed Central

    Adhikary, Till; Wortmann, Annika; Schumann, Tim; Finkernagel, Florian; Lieber, Sonja; Roth, Katrin; Toth, Philipp M.; Diederich, Wibke E.; Nist, Andrea; Stiewe, Thorsten; Kleinesudeik, Lara; Reinartz, Silke; Müller-Brüsselbach, Sabine; Müller, Rolf

    2015-01-01

    Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is a lipid ligand-inducible transcription factor with established metabolic functions, whereas its anti-inflammatory function is poorly understood. To address this issue, we determined the global PPARβ/δ-regulated signaling network in human monocyte-derived macrophages. Besides cell type-independent, canonical target genes with metabolic and immune regulatory functions we identified a large number of inflammation-associated NFκB and STAT1 target genes that are repressed by agonists. Accordingly, PPARβ/δ agonists inhibited the expression of multiple pro-inflammatory mediators and induced an anti-inflammatory, IL-4-like morphological phenotype. Surprisingly, bioinformatic analyses also identified immune stimulatory effects. Consistent with this prediction, PPARβ/δ agonists enhanced macrophage survival under hypoxic stress and stimulated CD8+ T cell activation, concomitantly with the repression of immune suppressive target genes and their encoded products CD274 (PD-1 ligand), CD32B (inhibitory Fcγ receptor IIB) and indoleamine 2,3-dioxygenase 1 (IDO-1), as well as a diminished release of the immune suppressive IDO-1 metabolite kynurenine. Comparison with published data revealed a significant overlap of the PPARβ/δ transcriptome with coexpression modules characteristic of both anti-inflammatory and pro-inflammatory cytokines. Our findings indicate that PPARβ/δ agonists induce a unique macrophage activation state with strong anti-inflammatory but also specific immune stimulatory components, pointing to a context-dependent function of PPARβ/δ in immune regulation. PMID:25934804

  12. Pharmacological characterization and therapeutic potential for the treatment of opioid abuse with ATPM-ET, an N-ethyl substituted aminothiazolomorphinan with κ agonist and μ agonist/antagonist activity.

    PubMed

    Sun, Jian-Feng; Wang, Yu-Hua; Chai, Jing-Rui; Li, Fu-Ying; Hang, Ai; Lu, Gang; Tao, Yi-Min; Cheng, Yun; Chi, Zhi-Qiang; Neumeyer, John L; Zhang, Ao; Liu, Jing-Gen; Wang, Yu-Jun

    2014-10-01

    We previously reported that the κ agonists with mixed μ activity could attenuate heroin self-administration with less potential to develop tolerance. The present study further investigated the effects of (-)-3-N-Ethylamino-thiazolo[5,4-b]-N-cyclopropylmethylmorphinan hydrochloride (ATPM-ET), a κ agonist and μ agonist/antagonist, on the acquisition and reinstatement of morphine-induced conditioned place preference (CPP), heroin self-administration and heroin-primed reinstatement of drug-seeking behavior. We found that ATPM-ET produced a longer duration of potent antinociceptive effects with less side effect of sedation. More importantly, ATPM-ET attenuated the acquisition of morphine-induced CPP, without affecting the reinstatement of morphine CPP. Furthermore, ATPM-ET significantly inhibited heroin self-administration and the reinstatement of heroin primed drug-seeking behavior. Taken together, ATPM-ET, a novel κ agonist and μ agonist/antagonist may have utility for the treatment of drug dependence. PMID:24998879

  13. Discovery and Structure-Activity Relationship Study of 4-Phenoxythiazol-5-carboxamides as Highly Potent TGR5 Agonists.

    PubMed

    Chen, Zhixiang; Ning, Mengmeng; Zou, Qingan; Cao, Hua; Ye, Yangliang; Leng, Ying; Shen, Jianhua

    2016-04-01

    A novel therapy that stimulates endogenous glucagon-like peptide-1 (GLP-1) secretion by Takeda G-protein-coupled receptor 5 (TGR5) agonists might be a superior alternative for the treatment of type 2 diabetes mellitus. A series of 4-phenoxythiazol-5-carboxamides were developed as highly potent TGR5 agonists using a bioisosteric replacement strategy based on the scaffold of 4-phenoxynicotinamides. The structure-activity relationship on the bottom phenyl ring and the thiazole ring was extensively studied, and the 2-methyl-thiazole derivatives 30c and e displayed the best in vitro potency toward human TGR5, with EC50 values of approximately 1 nM. While endowed with excellent in vitro potency, the 2-methyl-thiazoles were flawed with high microsomal clearance. PMID:26843013

  14. Correction for Inhibition Leads to an Allosteric Co-Agonist Model for Pentobarbital Modulation and Activation of α1β3γ2L GABAA Receptors

    PubMed Central

    Ziemba, Alexis M.; Forman, Stuart A.

    2016-01-01

    Background Pentobarbital, like propofol and etomidate, produces important general anesthetic effects through GABAA receptors. Photolabeling also indicates that pentobarbital binds to some of the same sites where propofol and etomidate act. Quantitative allosteric co-agonist models for propofol and etomidate account for modulatory and agonist effects in GABAA receptors and have proven valuable in establishing drug site characteristics and for functional analysis of mutants. We therefore sought to establish an allosteric co-agonist model for pentobarbital activation and modulation of α1β3γ2L receptors, using a novel approach to first correct pentobarbital activation data for inhibitory effects in the same concentration range. Methods Using oocyte-expressed α1β3γ2L GABAA receptors and two-microelectrode voltage-clamp, we quantified modulation of GABA responses by a low pentobarbital concentration and direct effects of high pentobarbital concentrations, the latter displaying mixed agonist and inhibitory effects. We then isolated and quantified pentobarbital inhibition in activated receptors using a novel single-sweep “notch” approach, and used these results to correct steady-state direct activation for inhibition. Results Combining results for GABA modulation and corrected direct activation, we estimated receptor open probability and optimized parameters for a Monod-Wyman-Changeux allosteric co-agonist model. Inhibition by pentobarbital was consistent with two sites with IC50s near 1 mM, while co-agonist model parameters suggest two allosteric pentobarbital agonist sites characterized by KPB ≈ 5 mM and high efficacy. The results also indicate that pentobarbital may be a more efficacious agonist than GABA. Conclusions Our novel approach to quantifying both inhibitory and co-agonist effects of pentobarbital provides a basis for future structure-function analyses of GABAA receptor mutations in putative pentobarbital binding sites. PMID:27110714

  15. Exploring pharmacological activities and signaling of morphinans substituted in position 6 as potent agonists interacting with the μ opioid receptor

    PubMed Central

    2014-01-01

    Background Opioid analgesics are the most effective drugs for the treatment of moderate to severe pain. However, they also produce several adverse effects that can complicate pain management. The μ opioid (MOP) receptor, a G protein-coupled receptor, is recognized as the opioid receptor type which primarily mediates the pharmacological actions of clinically used opioid agonists. The morphinan class of analgesics including morphine and oxycodone are of main importance as therapeutically valuable drugs. Though the natural alkaloid morphine contains a C-6-hydroxyl group and the semisynthetic derivative oxycodone has a 6-carbonyl function, chemical approaches have uncovered that functionalizing position 6 gives rise to a range of diverse activities. Hence, position 6 of N-methylmorphinans is one of the most manipulated sites, and is established to play a key role in ligand binding at the MOP receptor, efficacy, signaling, and analgesic potency. We have earlier reported on a chemically innovative modification in oxycodone resulting in novel morphinans with 6-acrylonitrile incorporated substructures. Results This study describes in vitro and in vivo pharmacological activities and signaling of new morphinans substituted in position 6 with acrylonitrile and amido functions as potent agonists and antinociceptive agents interacting with MOP receptors. We show that the presence of a 6-cyano group in N-methylmorphinans has a strong influence on the binding to the opioid receptors and post-receptor signaling. One 6-cyano-N-methylmorphinan of the series was identified as the highest affinity and most selective MOP agonist, and very potent in stimulating G protein coupling and intracellular calcium release through the MOP receptor. In vivo, this MOP agonist showed to be greatly effective against thermal and chemical nociception in mice with marked increased antinociceptive potency than the lead molecule oxycodone. Conclusion Development of such novel chemotypes by targeting position 6 provides valuable insights on ligand-receptor interaction and molecular mode of action, and may aid in identification of opioid therapeutics with enhanced analgesic properties and fewer undesirable effects. PMID:25059282

  16. Diabetes or peroxisome proliferator-activated receptor alpha agonist increases mitochondrial thioesterase I activity in heart

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peroxisome proliferator-activated receptor alpha (PPAR alpha) is a transcriptional regulator of the expression of mitochondrial thioesterase I (MTE-I) and uncoupling protein 3 (UCP3), which are induced in the heart at the mRNA level in response to diabetes. Little is known about the regulation of pr...

  17. The activation of Na+-dependent efflux of Ca2+ from liver mitochondria by glucagon and beta-adrenergic agonists.

    PubMed Central

    Goldstone, T P; Duddridge, R J; Crompton, M

    1983-01-01

    The Na+-induced efflux of Ca2+ from liver mitochondria was activated by tissue pretreatment with 1 microM-adrenaline, 1 microM-isoprenaline, 10 nM-glucagon and 100 microM-cyclic AMP when 10 mM-lactate plus 1 mM-pyruvate were present in the perfusion medium. Infusion of the alpha 1-adrenergic agonist, phenylephrine (10 microM), was ineffective. The activation induced by the beta-adrenergic agonist, isoprenaline, was maximal after infusion of agonist for 2 min. The isoprenaline-induced activation was very marked (120-220%), with about 7 nmol of intramitochondrial Ca2+/mg of protein, but was not evident with greater than 15 nmol of Ca2+/mg. Ca2+ efflux in the absence of Na+ and in the presence of the Ca2+ ionophore A23187 was not affected by isoprenaline pretreatment over the range 6-23 nmol of internal Ca2+/mg. With 10 mM-lactate plus 1 mM-pyruvate in the perfusion medium, glucagon and isoprenaline infusion increased tissue cyclic AMP content about 8-fold and 3-fold respectively. With 10 mM-pyruvate alone, neither glucagon nor isoprenaline caused a significant increase in cyclic AMP. Omission of lactate also abolished the ability of glucagon, but not of isoprenaline, to activate the Na+-induced efflux of Ca2+. The data indicate that cyclic AMP may mediate the activation caused by glucagon, but provide no evidence that cyclic AMP is an obligatory link in the beta-adrenergic-induced activation. PMID:6134523

  18. Promotion of Wound Healing by an Agonist of Adenosine A2A Receptor Is Dependent on Tissue Plasminogen Activator.

    PubMed

    Montesinos, M Carmen; Desai-Merchant, Avani; Cronstein, Bruce N

    2015-12-01

    Impaired wound healing, as it occurs in diabetes mellitus or long-term corticoid treatment, is commonly associated with disability, diminished quality of life, and high economic costs. Selective agonists of the A2A receptor subtype of adenosine, an endogenous regulator of inflammation, promote tissue repair in animal models, both healthy and with impaired healing. Plasmin-mediated proteolysis of fibrin and other matrix proteins is essential for cell migration at sites of injury. Since adenosine A2A receptor activation increases plasminogen activator release from macrophages and mast cells, we studied the effect of a selective agonist, CGS-21680, on full-thickness excisional wound closure in wild-type, urokinase plasminogen activator (uPA)-deficient, and tissue plasminogen activator (tPA)-deficient mice. Wound closure was impaired in tPA- and uPA-deficient mice as compared with wild-type mice, and topical application of CGS-21680 significantly increased the rate at which wounds closed in wild-type mice and uPA-deficient mice, but not in tPA-deficient mice. Immunostaining of tissue sections showed that tPA was present in endothelial cells and histiocytes by day 3 post-wound and also by day 6. In contrast, uPA was more prominent in these cell types only by day 6 post-wound. Our results confirm that plasminogen activation contributes to wound repair and are consistent with the hypothesis that adenosine A2A receptor activation promotes wound closure by a mechanism that depends upon tPA, but not uPA. Moreover, our results suggest that topical adenosine A2A receptor agonists may be useful in promotion of wound closure in patients with impaired wound healing. PMID:25991438

  19. Food flavonoid aryl hydrocarbon receptor-mediated agonistic/antagonistic/synergic activities in human and rat reporter gene assays.

    PubMed

    Van der Heiden, Edwige; Bechoux, Nathalie; Muller, Marc; Sergent, Thérèse; Schneider, Yves-Jacques; Larondelle, Yvan; Maghuin-Rogister, Guy; Scippo, Marie-Louise

    2009-04-01

    Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor mediating the adverse effects of dioxins and polycyclic aromatic hydrocarbons (PAHs). In this study, we investigated the genetic-, time-, dose-, species- and tissue-dependent AhR-mediated agonistic/antagonistic activities of three food flavonoids: quercetin, chrysin and genistein. To that end, four stably transfected cell lines were used in cell-based luciferase reporter gene assays: three lines were transformed with the ptKLuc vector harbouring four dioxin-responsive elements (DREs) upstream of the thymidine kinase promoter and the luciferase gene (HepG2-Luc, T-47D-Luc and H4IIE-ULg). The fourth is a patented cell line transformed with a different construct: H4IIE DR-CALUX((R)). Both H4IIE cells were compared for their genetic construction. Human hepatoma (HepG2-Luc) and human breast tumour (T-47D-Luc) cells were compared for tissue-dependent effects. Rat hepatoma (H4IIE-ULg) and human hepatoma (HepG2-Luc) cells were compared for species-dependent activities. We concluded that quercetin, chrysin and genistein act in a time-, dose-, species- and tissue-specific way. For example, genistein displayed agonistic activities when exposed to rat hepatoma cells during 6h but not after 24h. Flavonoids displayed agonistic/antagonistic activities in human breast tumour cells, depending on the exposure time, while in human hepatoma cells, only antagonistic activities of flavonoids were measured. In addition, we report, in all the cells, a synergy between an isoflavone and two food contaminants; the 2,3,7,8-tetrachlorodibenzo-p-dioxin and 3-methylcholanthrene, a PAH. In rat cells, this synergy occurred when cells were exposed to flavonoids and contaminant for 6h, while it was observed in human cells only after 24h. PMID:19286049

  20. Alpha 2-adrenergic, but not imidazole, agonists activate NaCl cotransport in rabbit tracheal epithelial cells.

    PubMed

    Liedtke, C M; Furin, J; Ernsberger, P

    1993-03-01

    The adrenergic agonist clonidine activates NaCl cotransport in rabbit tracheocytes. With the use of the high-affinity analogue p-[125I]iodoclonidine, binding of clonidine to cells was determined to fit a two-site model, with one site of high specificity for alpha 2-adrenergic (alpha 2-AR) and the other with a high affinity for I1-imidazol(in)e (I1) receptors. Total density of binding sites for both receptors was similar at 18 fmol/mg protein. Moxonidine displayed a 166-fold greater specificity for I1 receptors compared with cimetidine. Bumetanide-sensitive Na or Cl transport was stimulated by the alpha 2-AR agonists clonidine or guanabenz but not by the I1 agents cimetidine or moxonidine. I1 agonists-stimulated Na transport was detected only in the presence of bumetanide. Prazosin did not block clonidine-stimulated NaCl uptake or efflux, indicating the presence of an alpha 2A-AR subtype. Addition of clonidine either before or after incubation with l-isoproterenol or forskolin did not attenuate the time- and dose-dependent increase in adenosine 3',5'-cyclic monophosphate (cAMP) levels. Thus clonidine stimulates NaCl cotransport in rabbit tracheocytes through an alpha 2A-AR mechanism that does not require cAMP for signal transduction. In addition, I1-imidazol(in)e receptors stimulate Na transport in rabbit tracheocytes through an unidentified pathway. PMID:8096363

  1. Characterization of estrogenic receptor agonists and evaluation of estrogenic activity in the sediments of Liaohe River protected areas.

    PubMed

    Ke, Xin; Wang, Chunyong; Zhang, Haijun; Zhang, Yun; Gui, Shaofeng

    2015-11-15

    Estrogenic activity of 12 sediment samples from Liaohe River protected areas was evaluated by the recombinant yeast bioassays. The bioassay-derived 17β-estradiol equivalents of crude extracts (Bio-EEQcrudes) were between 52.2 and 207.6pg/g dry weight. The most concerned estrogenic receptor (ER) agonists including estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), 4-nonylphenols (4-NP), bisphenol A (BPA), and organochlorine pesticides (OCPs) were determined. The concentrations of E1, E2, E3, EE2, BPA, andΣ10OCPs ranged up to 203.3pg/g, 185.8pg/g, 237.7pg/g, 188.5pg/g, 51.0ng/g, and 3.6ng/g, respectively. Taken together with polarity-based fractionation, in vitro bioassay and chemical analysis, it indicated that E1, E2, and EE2 were the predominant ER agonists and were mainly from the discharge of domestic wastewater and breeding wastewater. Meanwhile, this study showed that the establishment of protected areas had not obviously reduced the ecological risk caused by ER agonists in Liaohe River protected areas sediments. PMID:26388445

  2. Parallel Functional Activity Profiling Reveals Valvulopathogens Are Potent 5-Hydroxytryptamine2B Receptor Agonists: Implications for Drug Safety Assessment

    PubMed Central

    Huang, Xi-Ping; Setola, Vincent; Yadav, Prem N.; Allen, John A.; Rogan, Sarah C.; Hanson, Bonnie J.; Revankar, Chetana; Robers, Matt; Doucette, Chris

    2009-01-01

    Drug-induced valvular heart disease (VHD) is a serious side effect of a few medications, including some that are on the market. Pharmacological studies of VHD-associated medications (e.g., fenfluramine, pergolide, methysergide, and cabergoline) have revealed that they and/or their metabolites are potent 5-hydroxytryptamine2B (5-HT2B) receptor agonists. We have shown that activation of 5-HT2B receptors on human heart valve interstitial cells in vitro induces a proliferative response reminiscent of the fibrosis that typifies VHD. To identify current or future drugs that might induce VHD, we screened approximately 2200 U.S. Food and Drug Administration (FDA)-approved or investigational medications to identify 5-HT2B receptor agonists, using calcium-based high-throughput screening. Of these 2200 compounds, 27 were 5-HT2B receptor agonists (hits); 14 of these had previously been identified as 5-HT2B receptor agonists, including seven bona fide valvulopathogens. Six of the hits (guanfacine, quinidine, xylometazoline, oxymetazoline, fenoldopam, and ropinirole) are approved medications. Twenty-three of the hits were then “functionally profiled” (i.e., assayed in parallel for 5-HT2B receptor agonism using multiple readouts to test for functional selectivity). In these assays, the known valvulopathogens were efficacious at concentrations as low as 30 nM, whereas the other compounds were less so. Hierarchical clustering analysis of the pEC50 data revealed that ropinirole (which is not associated with valvulopathy) was clearly segregated from known valvulopathogens. Taken together, our data demonstrate that patterns of 5-HT2B receptor functional selectivity might be useful for identifying compounds likely to induce valvular heart disease. PMID:19570945

  3. Functional selectivity of dopamine receptor agonists. I. Selective activation of postsynaptic dopamine D2 receptors linked to adenylate cyclase.

    PubMed

    Mottola, David M; Kilts, Jason D; Lewis, Mechelle M; Connery, Hilary S; Walker, Q David; Jones, Sara R; Booth, Raymond G; Hyslop, Deborah K; Piercey, Monford; Wightman, R Mark; Lawler, Cindy P; Nichols, David E; Mailman, Richard B

    2002-06-01

    Dihydrexidine (DHX), the first high-affinity D(1) dopamine receptor full agonist, is only 10-fold selective for D(1) versus D(2) receptors, having D(2) affinity similar to the prototypical agonist quinpirole. The D(2) functional properties of DHX and its more D(2) selective analog N-n-propyl-dihydrexidine (PrDHX) were explored in rat brain and pituitary. DHX and PrDHX had binding characteristics to D(2) receptors in rat striatum typical of D(2) agonists, binding to both high- and low-affinity sites and being sensitive to guanine-nucleotides. Consistent with these binding data, both DHX and PrDHX inhibited forskolin-stimulated cAMP synthesis in striatum with a potency and intrinsic activity equivalent to that of quinpirole. Unexpectedly, however, DHX and PrDHX had little functional effect at D(2) receptors expressed on dopaminergic neurons that mediate inhibition of cell firing, dopamine release, or dopamine synthesis. Quantitative receptor competition autoradiography demonstrated that DHX bound to D(2) receptors in striatum (predominantly postsynaptic receptor sites) with equal affinity as D(2) sites in the substantia nigra (autoreceptor sites). The data from these experiments, coupled with what is known about the location of specific dopamine receptor isoforms, lead to the hypothesis that DHX, after binding to D(2L) and D(2S) receptors, causes agonist-typical functional changes only at some of these receptors. This phenomenon (herein termed "functional selectivity") suggests that drugs may be targeted not only at specific receptor isoforms but also at separate functions mediated by a single isoform, yielding novel approaches to drug discovery. PMID:12023552

  4. Parallel functional activity profiling reveals valvulopathogens are potent 5-hydroxytryptamine(2B) receptor agonists: implications for drug safety assessment.

    PubMed

    Huang, Xi-Ping; Setola, Vincent; Yadav, Prem N; Allen, John A; Rogan, Sarah C; Hanson, Bonnie J; Revankar, Chetana; Robers, Matt; Doucette, Chris; Roth, Bryan L

    2009-10-01

    Drug-induced valvular heart disease (VHD) is a serious side effect of a few medications, including some that are on the market. Pharmacological studies of VHD-associated medications (e.g., fenfluramine, pergolide, methysergide, and cabergoline) have revealed that they and/or their metabolites are potent 5-hydroxytryptamine(2B) (5-HT(2B)) receptor agonists. We have shown that activation of 5-HT(2B) receptors on human heart valve interstitial cells in vitro induces a proliferative response reminiscent of the fibrosis that typifies VHD. To identify current or future drugs that might induce VHD, we screened approximately 2200 U.S. Food and Drug Administration (FDA)-approved or investigational medications to identify 5-HT(2B) receptor agonists, using calcium-based high-throughput screening. Of these 2200 compounds, 27 were 5-HT(2B) receptor agonists (hits); 14 of these had previously been identified as 5-HT(2B) receptor agonists, including seven bona fide valvulopathogens. Six of the hits (guanfacine, quinidine, xylometazoline, oxymetazoline, fenoldopam, and ropinirole) are approved medications. Twenty-three of the hits were then "functionally profiled" (i.e., assayed in parallel for 5-HT(2B) receptor agonism using multiple readouts to test for functional selectivity). In these assays, the known valvulopathogens were efficacious at concentrations as low as 30 nM, whereas the other compounds were less so. Hierarchical clustering analysis of the pEC(50) data revealed that ropinirole (which is not associated with valvulopathy) was clearly segregated from known valvulopathogens. Taken together, our data demonstrate that patterns of 5-HT(2B) receptor functional selectivity might be useful for identifying compounds likely to induce valvular heart disease. PMID:19570945

  5. In vitro autoradiography of receptor-activated G proteins in rat brain by agonist-stimulated guanylyl 5'-[gamma-[35S]thio]-triphosphate binding.

    PubMed Central

    Sim, L J; Selley, D E; Childers, S R

    1995-01-01

    Agonists stimulate guanylyl 5'-[gamma-[35S]thio]-triphosphate (GTP[gamma-35S]) binding to receptor-coupled guanine nucleotide binding protein (G proteins) in cell membranes as revealed in the presence of excess GDP. We now report that this reaction can be used to neuroanatomically localize receptor-activated G proteins in brain sections by in vitro autoradiography of GTP[gamma-35S] binding. Using the mu opioid-selective peptide [D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO) as an agonist in rat brain sections and isolated thalamic membranes, agonist stimulation of GTP[gamma-35S] binding required the presence of excess GDP (1-2 mM GDP in sections vs. 10-30 microM GDP in membranes) to decrease basal G-protein activity and reveal agonist-stimulated GTP[gamma-35S] binding. Similar concentrations of DAMGO were required to stimulate GTP[gamma-35S] binding in sections and membranes. To demonstrate the general applicability of the technique, agonist-stimulated GTP[gamma-35S] binding in tissue sections was assessed with agonists for the mu opioid (DAMGO), cannabinoid (WIN 55212-2), and gamma-aminobutyric acid type B (baclofen) receptors. For opioid and cannabinoid receptors, agonist stimulation of GTP[gamma-35S] binding was blocked by incubation with agonists in the presence of the appropriate antagonists (naloxone for mu opioid and SR-141716A for cannabinoid), thus demonstrating that the effect was specifically receptor mediated. The anatomical distribution of agonist-stimulated GTP[gamma-35S] binding qualitatively paralleled receptor distribution as determined by receptor binding autoradiography. However, quantitative differences suggest that variations in coupling efficiency may exist between different receptors in various brain regions. This technique provides a method of functional neuroanatomy that identifies changes in the activation of G proteins by specific receptors. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:7638174

  6. PPAR{gamma} agonist pioglitazone reduces matrix metalloproteinase-9 activity and neuronal damage after focal cerebral ischemia

    SciTech Connect

    Lee, Seong-Ryong; Kim, Hahn-Young; Hong, Jung-Suk; Baek, Won-Ki; Park, Jong-Wook

    2009-02-27

    Pioglitazone, a peroxisome proliferator-activated receptor gamma (PPAR{gamma}) agonist, has shown protective effects against ischemic insult in various tissues. Pioglitazone is also reported to reduce matrix metalloproteinase (MMP) activity. MMPs can remodel extracellular matrix components in many pathological conditions. The current study was designed to investigate whether the neuroprotection of pioglitazone is related to its MMP inhibition in focal cerebral ischemia. Mice were subjected to 90 min focal ischemia and reperfusion. In gel zymography, pioglitazone reduced the upregulation of active form of MMP-9 after ischemia. In in situ zymograms, pioglitazone also reduced the gelatinase activity induced by ischemia. After co-incubation with pioglitazone, in situ gelatinase activity was directly reduced. Pioglitazone reduced the infarct volume significantly compared with controls. These results demonstrate that pioglitazone may reduce MMP-9 activity and neuronal damage following focal ischemia. The reduction of MMP-9 activity may have a possible therapeutic effect for the management of brain injury after focal ischemia.

  7. Structure-activity relationship studies on cholecystokinin: Analogues with partial agonist activity

    SciTech Connect

    Galas, M.C.; Lignon, M.F.; Rodriguez, M.; Mendre, C.; Fulcrand, P.; Laur, J.; Martinez, J. )

    1988-02-01

    In the present study, hepta- and octapeptide analogues of the C-terminal part of cholecystokinin, modified on the C-terminal phenylalanine residue, were synthesized. CCK analogues were prepared in which the peptide bond between aspartic acid and phenylalanine had or had not been modified and were lacking the C-terminal primary amide function. These CCK derivatives were able to cause full stimulation of amylase release from rat pancreatic acini but without a decrease in amylase release at supramaximal concentrations. There was a close relationship between the abilities of these derivatives to stimulate amylase release and their abilities to inhibit binding of {sup 125}I-BH-CCK-9 to CCK receptors on rat and guinea pig pancreatic acini. These CCK analogues were also able to recognize the guinea pig brain CCK receptors, some of them being particularly potent. The findings indicate that the aromatic ring of phenylalanine is important for the binding to brain and pancreatic CCK receptors, whereas the C-terminal primary amide function is not essential for the binding to pancreatic CCK receptors but is crucial for biological activity of rat pancreatic acini.

  8. Synthetic partial agonists reveal key steps in IP3 receptor activation

    PubMed Central

    Rossi, Ana M.; Riley, Andrew M.; Tovey, Stephen C.; Taufiq-Ur-Rahman; Dellis, Olivier; Taylor, Emily J. A.; Veresov, Valery G.; Potter, Barry V. L.; Taylor, Colin W.

    2009-01-01

    Inositol 1,4,5-trisphosphate receptors (IP3R) are ubiquitous intracellular Ca2+ channels. IP3binding to the IP3-binding core (IBC) near the N-terminal initiates conformational changes that lead to opening of a pore. The mechanisms are unresolved. We synthesized 2-O-modified IP3 analogues that are partial agonists of IP3R. These are like IP3 in their interactions with the IBC, but they are less effective than IP3 in rearranging the relationship between the IBC and N-terminal suppressor domain (SD), and they open the channel at slower rates. IP3R with a mutation in the SD occupying a position similar to the 2-O-substituent of the partial agonists has a reduced open probability that is similar for full and partial agonists. Bulky or charged substituents from either the ligand or SD therefore block obligatory coupling of the IBC and SD. Analysis of ΔG for ligand binding shows that IP3 is recognised by the IBC and conformational changes then propagate entirely via the SD to the pore. PMID:19668195

  9. Acute fatigue impairs neuromuscular activity of anterior cruciate ligament-agonist muscles in female team handball players.

    PubMed

    Zebis, M K; Bencke, J; Andersen, L L; Alkjaer, T; Suetta, C; Mortensen, P; Kjaer, M; Aagaard, P

    2011-12-01

    In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury. Fourteen female team handball players were tested for neuromuscular activity [electromyography (EMG)] during a sidecutting maneuver on a force plate, pre and post a simulated handball match. MVC was obtained during maximal isometric quadriceps and hamstring contraction. The simulated handball match consisted of exercises mimicking handball match activity. Whereas the simulated handball match induced a decrease in MVC strength for both the quadriceps and hamstring muscles (P<0.05), a selective decrease in hamstring neuromuscular activity was seen during sidecutting (P<0.05). This study shows impaired ACL-agonist muscle (i.e. hamstring) activity during sidecutting in response to acute fatigue induced by handball match play. Thus, screening procedures should involve functional movements to reveal specific fatigue-induced deficits in ACL-agonist muscle activation during high-risk phases of match play. PMID:20500560

  10. Design, synthesis and structure-activity relationship studies of novel phenoxyacetamide-based free fatty acid receptor 1 agonists for the treatment of type 2 diabetes.

    PubMed

    Li, Zheng; Wang, Xuekun; Xu, Xue; Yang, Jianyong; Qiu, Qianqian; Qiang, Hao; Huang, Wenlong; Qian, Hai

    2015-10-15

    The free fatty acid receptor 1 (FFA1) has attracted extensive attention as a novel antidiabetic target in the last decade. Several FFA1 agonists reported in the literature have been suffered from relatively high molecular weight and lipophilicity. We have previously reported the FFA1 agonist 1. Based on the common amide structural characteristic of SAR1 and NIH screened compound, we here describe the continued structure-activity exploration to decrease the molecular weight and lipophilicity of the compound 1 series by converting various amide linkers. All of these efforts lead to the discovery of the preferable lead compound 18, a compound with considerable agonistic activity, high LE and LLE values, lower lipophilicity than previously reported agonists, and appreciable efficacy on glucose tolerance in both normal and type 2 diabetic mice. PMID:26420383

  11. (1R, 3S)-(−)-Trans-PAT: A novel full-efficacy serotonin 5-HT2C receptor agonist with 5-HT2A and 5-HT2B receptor inverse agonist/antagonist activity

    PubMed Central

    Booth, Raymond G.; Fang, Lijuan; Huang, Yingsu; Wilczynski, Andrzej; Sivendran, Sashikala

    2009-01-01

    The serotonin 5-HT2A, 5-HT2B, and 5-HT2C G protein-coupled receptors signal primarily through Gαq to activate phospholipase C (PLC) and formation of inositol phosphates (IP) and diacylglycerol. The human 5-HT2C receptor, expressed exclusively in the central nervous system, is involved in several physiological and psychological processes. Development of 5-HT2C agonists that do not also activate 5-HT2A or 5-HT2B receptors is challenging because transmembrane domain identity is about 75% among 5-HT2 subtypes. This paper reports 5-HT2 receptor affinity and function of (1R,3S)-(−)-trans-1-phenyl-3-dimethylamino-1,2,3,4-tetrahydronaphthalene (PAT), a small molecule that produces anorexia and weight-loss after peripheral administration to mice. (−)-Trans-PAT is a stereoselective full-efficacy agonist at human 5-HT2C receptors, plus, it is a 5-HT2A/5-HT2B inverse agonist and competitive antagonist. The Ki of (−)-trans-PAT at 5-HT2A, 5-HT2B, and 5-HT2C receptors is 410, 1200, and 37 nM, respectively. Functional studies measured activation of PLC/[3H]-IP formation in clonal cells expressing human 5-HT2 receptors. At 5-HT2C receptors, (−)-trans-PAT is an agonist (EC50 = 20 nM) comparable to serotonin in potency and efficacy. At 5-HT2A and 5-HT2B receptors, (−)-trans-PAT is an inverse agonist (IC50 = 490 and 1,000 nM, respectively) and competitive antagonist (KB = 460 and 1400 nM, respectively) of serotonin. Experimental results are interpreted in light of molecular modeling studies indicating the (−)-trans-PAT protonated amine can form an ionic bond with D3.32 of 5-HT2A and 5-HT2C receptors, but, not with 5-HT2B receptors. In addition to probing 5-HT2 receptor structure and function, (−)-trans-PAT is a novel lead regarding 5-HT2C agonist/5-HT2A inverse agonist drug development for obesity and neuropsychiatric disorders. PMID:19397907

  12. Differential regulation of the mitogen-activated protein and stress-activated protein kinase cascades by adrenergic agonists in quiescent and regenerating adult rat hepatocytes.

    PubMed Central

    Spector, M S; Auer, K L; Jarvis, W D; Ishac, E J; Gao, B; Kunos, G; Dent, P

    1997-01-01

    To study the mechanisms by which catecholamines regulate hepatocyte proliferation after partial hepatectomy (PHX), hepatocytes were isolated from adult male rats 24 h after sham operation or two-thirds PHX and treated with catecholamines and other agonists. In freshly isolated sham cells, p42 mitogen-activated protein (MAP) kinase activity was stimulated by the alpha1-adrenergic agonist phenylephrine (PHE). Activation of p42 MAP kinase by growth factors was blunted by pretreatment of sham hepatocytes with glucagon but not by that with the beta2-adrenergic agonist isoproterenol (ISO). In PHX cells, the ability of PHE to activate p42 MAP kinase was dramatically reduced, whereas ISO became competent to inhibit p42 MAP kinase activation. PHE treatment of sham but not PHX and ISO treatment of PHX but not sham hepatocytes also activated the stress-activated protein (SAP) kinases p46/54 SAP kinase and p38 SAP kinase. These data demonstrate that an alpha1- to beta2-adrenergic receptor switch occurs upon PHX and results in an increase in SAP kinase versus MAP kinase signaling by catecholamines. In primary cultures of hepatocytes, ISO treatment of PHX but not sham cells inhibited [3H]thymidine incorporation. In contrast, PHE treatment of sham but not PHX cells stimulated [3H]thymidine incorporation, which was reduced by approximately 25 and approximately 95% with specific inhibitors of p42 MAP kinase and p38 SAP kinase function, respectively. Inhibition of the p38 SAP kinase also dramatically reduced basal [3H]thymidine incorporation. These data suggest that p38 SAP kinase plays a permissive role in liver regeneration. Alterations in the abilities of catecholamines to modulate the activities of protein kinase A and the MAP and SAP kinase pathways may represent one physiological mechanism by which these agonists can regulate hepatocyte proliferation after PHX. PMID:9199291

  13. The peroxisome proliferator-activated receptor-γ agonist pioglitazone protects against cisplatin-induced renal damage in mice.

    PubMed

    Jesse, Cristiano R; Bortolatto, Cristiani F; Wilhelm, Ethel A; Roman, Silvane Souza; Prigol, Marina; Nogueira, Cristina W

    2014-01-01

    Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists not only improve metabolic abnormalities of diabetes and consequent diabetic nephropathy, but they also protect against non-diabetic kidney disease in experimental models. Here, we investigated the effect of PPAR-γ agonist pioglitazone against acute renal injury on a cisplatin model in mice. Nephrotoxicity was induced by a single intraperitoneal (i.p.) injection of cisplatin (10 mg kg(-1)). Pioglitazone was administered for six consecutive days in doses of 15 or 30 mg kg(-1)  day(-1), per os (p.o.), starting 3 days before cisplatin injection. Cisplatin treatment to mice induced a marked renal failure, characterized by a significant increase in serum urea and creatinine levels and alterations in renal tissue architecture. Cisplatin exposure induced oxidative stress as indicated by decreased levels of non-enzymatic antioxidant defenses [glutathione (GSH) and ascorbic acid levels] and components of the enzymatic antioxidant defenses [superoxide dismutase (SOD), catalase (CAT) glutathione peroxidase (GPx), glutathione reductase (GR) and and glutathione S-transferase(GST) activities)] in renal tissue. Administration of pioglitazone markedly protected against the increase in urea and creatinine levels and histological alterations in kidney induced by cisplatin treatment. Pioglitazone administration ameliorated GSH and ascorbic acid levels decreased by cisplatin exposure in mice. Pioglitazone protected against the inhibition of CAT, SOD, GPx, GR and GST activities induced by cisplatin in the kidneys of mice. These results indicated that pioglitazone has a protective effect against cisplatin-induced renal damage in mice. The protection is mediated by preventing the decline of antioxidant status. The results have implications in use of PPAR-γ agonists in human application for protecting against drugs-induced nephrotoxicity. PMID:22987311

  14. Identification of novel estrogen receptor (ER) agonists that have additional and complementary anti-cancer activities via ER-independent mechanism.

    PubMed

    Kim, Taelim; Kim, Hye-In; An, Ji-Young; Lee, Jun; Lee, Na-Rae; Heo, Jinyuk; Kim, Ji-Eun; Yu, Jihyun; Lee, Yong Sup; Inn, Kyung-Soo; Kim, Nam-Jung

    2016-04-01

    In this study, a series of bis(4-hydroxy)benzophenone oxime ether derivatives such as 12c, 12e and 12h were identified as novel estrogen receptor (ER) agonists that have additional and complementary anti-proliferative activities via ER-independent mechanism in cancer cells. These compounds are expected to overcome the therapeutic limitation of existing ER agonists such as estradiol and tamoxifen, which have been known to induce the proliferation of cancer cells. PMID:26905830

  15. PPAR-γ agonist stabilizes KLF4 protein via activating Akt signaling and reducing KLF4 ubiquitination

    SciTech Connect

    Sun, Yan; Zheng, Bin; Zhang, Xin-hua; He, Ming; Guo, Zong-wei; Wen, Jin-kun

    2014-01-10

    Highlights: •PPAR-γ increases KLF4 protein level but does not influence KLF4 gene transcription. •The increase of KLF4 protein levels induced by pioglitazone is PPAR-γ-dependent. •Pioglitazone stabilizes KLF4 protein via activating Akt signaling and reducing KLF4 ubiquitination. -- Abstract: Peroxisome proliferator activated receptor γ (PPAR-γ) plays important roles in cell cycle regulation, differentiation and apoptosis. Krüppel-like factor 4 (KLF4) modulates vascular smooth muscle cell (VSMC) phenotype. Both KLF4 and PPAR-γ are involved in VSMC proliferation and differentiation. However, the actual relationship between KLF4 and PPAR-γ in VSMCs is not clear. In this study, we found that PPAR-γ agonist pioglitazone increases KLF4 protein levels but does not influence KLF4 gene transcription. PPAR-γ overexpression increases, while PPAR-γ knockdown reduces KLF4 expression, suggesting that the increase in KLF4 protein levels induced by pioglitazone is PPAR-γ-dependent. Further study showed that pioglitazone enhances KLF4 protein stability through reducing KLF4 ubiquitination. Furthermore, we demonstrated that stabilization of KLF4 by pioglitazone was related to the activation of Akt signaling pathway. Taken together, we revealed that PPAR-γ agonist pioglitazone stabilizes KLF4 protein via activating Akt signaling and reducing KLF4 ubiquitination, providing further insights into PPAR-γ and KLF4 in regulating each other’s expression in VSMCs.

  16. Effect of sulphation on the oestrogen agonist activity of the phytoestrogens genistein and daidzein in MCF-7 human breast cancer cells.

    PubMed

    Pugazhendhi, D; Watson, K A; Mills, S; Botting, N; Pope, G S; Darbre, P D

    2008-06-01

    The phytoestrogens genistein, daidzein and the daidzein metabolite equol have been shown previously to possess oestrogen agonist activity. However, following consumption of soya diets, they are found in the body not only as aglycones but also as metabolites conjugated at their 4'- and 7-hydroxyl groups with sulphate. This paper describes the effects of monosulphation on the oestrogen agonist properties of these three phytoestrogens in MCF-7 human breast cancer cells in terms of their relative ability to compete with [(3)H]oestradiol for binding to oestrogen receptor (ER), to induce a stably transfected oestrogen-responsive reporter gene (ERE-CAT) and to stimulate cell growth. In no case did sulphation abolish activity. The 4'-sulphation of genistein reduced oestrogen agonist activity to a small extent in whole-cell assays but increased the relative binding affinity to ER. The 7-sulphation of genistein, and also of equol, reduced oestrogen agonist activity substantially in all assays. By contrast, the position of monosulphation of daidzein acted in an opposing manner on oestrogen agonist activity. Sulphation at the 4'-position of daidzein resulted in a modest reduction in oestrogen agonist activity but sulphation of daidzein at the 7-position resulted in an increase in oestrogen agonist activity. Molecular modelling and docking studies suggested that the inverse effects of sulphation could be explained by the binding of daidzein into the ligand-binding domain of the ER in the opposite orientation compared with genistein and equol. This is the first report of sulphation enhancing activity of an isoflavone and inverse effects of sulphation between individual phytoestrogens. PMID:18492816

  17. Effect of sulphation on the oestrogen agonist activity of the phytoestrogens genistein and daidzein in MCF-7 human breast cancer cells

    PubMed Central

    Pugazhendhi, D; Watson, K A; Mills, S; Botting, N; Pope, G S; Darbre, P D

    2008-01-01

    The phytoestrogens genistein, daidzein and the daidzein metabolite equol have been shown previously to possess oestrogen agonist activity. However, following consumption of soya diets, they are found in the body not only as aglycones but also as metabolites conjugated at their 4′- and 7-hydroxyl groups with sulphate. This paper describes the effects of monosulphation on the oestrogen agonist properties of these three phytoestrogens in MCF-7 human breast cancer cells in terms of their relative ability to compete with [3H]oestradiol for binding to oestrogen receptor (ER), to induce a stably transfected oestrogen-responsive reporter gene (ERE-CAT) and to stimulate cell growth. In no case did sulphation abolish activity. The 4′-sulphation of genistein reduced oestrogen agonist activity to a small extent in whole-cell assays but increased the relative binding affinity to ER. The 7-sulphation of genistein, and also of equol, reduced oestrogen agonist activity substantially in all assays. By contrast, the position of monosulphation of daidzein acted in an opposing manner on oestrogen agonist activity. Sulphation at the 4′-position of daidzein resulted in a modest reduction in oestrogen agonist activity but sulphation of daidzein at the 7-position resulted in an increase in oestrogen agonist activity. Molecular modelling and docking studies suggested that the inverse effects of sulphation could be explained by the binding of daidzein into the ligand-binding domain of the ER in the opposite orientation compared with genistein and equol. This is the first report of sulphation enhancing activity of an isoflavone and inverse effects of sulphation between individual phytoestrogens. PMID:18492816

  18. Inhibition of indoleamine 2,3-dioxygenase activity enhances the anti-tumour effects of a Toll-like receptor 7 agonist in an established cancer model

    PubMed Central

    Ito, Hiroyasu; Ando, Tatsuya; Arioka, Yuko; Saito, Kuniaki; Seishima, Mitsuru

    2015-01-01

    Toll-like receptor (TLR) agonists have been shown to have anti-tumour activity in basic research and clinical studies. However, TLR agonist monotherapy does not sufficiently eliminate tumours. Activation of the innate immune response by TLR agonists is effective at driving adaptive immunity via interleukin-12 (IL-12) or IL-1, but is counteracted by the simultaneous induction of immunosuppressive cytokines and other molecules, including IL-10, transforming growth factor-β, and indoleamine 2,3-dioxygenase (IDO). In the present study, we evaluated the anti-cancer effect of the TLR7 agonist, imiquimod (IMQ), in the absence of IDO activity. The administration of IMQ in IDO knockout (KO) mice inoculated with tumour cells significantly suppressed tumour progression compared with that in wild-type (WT) mice, and improved the survival rate. Moreover, injection with IMQ enhanced the tumour antigen-specific T helper type 1 response in IDO-KO mice with tumours. Combination therapy with IMQ and an IDO inhibitor also significantly inhibited tumour growth. Our results indicated that the enhancement of IDO expression with TLR agonists in cancer treatment might impair host anti-tumour immunity while the inhibition of IDO could enhance the therapeutic efficacy of TLR agonists via the increase of T helper type 1 immune response. PMID:25322876

  19. An Orally Active Allosteric GLP-1 Receptor Agonist Is Neuroprotective in Cellular and Rodent Models of Stroke

    PubMed Central

    Qu, Di; Wang, Ling; Wang, Xinshang; Li, Xubo; Zhou, Shimeng; Zhou, Ying; Wang, Ning; Meng, Jingru; Ma, Xue

    2016-01-01

    Diabetes is a major risk factor for the development of stroke. Glucagon-like peptide-1 receptor (GLP-1R) agonists have been in clinical use for the treatment of diabetes and also been reported to be neuroprotective in ischemic stroke. The quinoxaline 6,7-dichloro-2-methylsulfonyl-3-N-tert- butylaminoquinoxaline (DMB) is an agonist and allosteric modulator of the GLP-1R with the potential to increase the affinity of GLP-1 for its receptor. The aim of this study was to evaluate the neuroprotective effects of DMB on transient focal cerebral ischemia. In cultured cortical neurons, DMB activated the GLP-1R, leading to increased intracellular cAMP levels with an EC50 value about 100 fold that of exendin-4. Pretreatment of neurons with DMB protected against necrotic and apoptotic cell death was induced by oxygen-glucose deprivation (OGD). The neuroprotective effects of DMB were blocked by GLP-1R knockdown with shRNA but not by GLP-1R antagonism. In C57BL/6 mice, DMB was orally administered 30 min prior to middle cerebral artery occlusion (MCAO) surgery. DMB markedly reduced the cerebral infarct size and neurological deficits caused by MCAO and reperfusion. The neuroprotective effects were mediated by activation of the GLP-1R through the cAMP-PKA-CREB signaling pathway. DMB exhibited anti-apoptotic effects by modulating Bcl-2 family members. These results provide evidence that DMB, a small molecular GLP-1R agonist, attenuates transient focal cerebral ischemia injury and inhibits neuronal apoptosis induced by MCAO. Taken together, these data suggest that DMB is a potential neuroprotective agent against cerebral ischemia. PMID:26863436

  20. Antitumor activity of a novel small molecule TLR7 agonist via immune response induction and tumor microenvironment modulation.

    PubMed

    Diao, Yuwen; Wang, Xiaodong; Wan, Yanyan; Zhong, Jingjing; Gao, Dong; Liu, Yu; Gao, Ningning; Li, Wang; Liu, Bing; Huang, Xinping; Jin, Zhenchao; Peng, Boya; Wang, Zhulin; Fu, Li; Chen, Siping; Jin, Guangyi

    2016-02-01

    Immunotherapy is emerging as a powerful and active tumor-specific approach against cancer via triggering the immune system. Toll-like receptors (TLRs) are fundamental elements of the immune system, which facilitate our understanding of the innate and adaptive immune pathways. TLR agonists used as single agents can effectively eradicate tumors due to their potent stimulation of innate and adaptive immunity. We examined the effects of a novel adenine type of TLR7 agonists on both innate and adaptive immune activation in vitro and in vivo. We established the local and distant tumor‑bearing mice derived from murine mammary carcinoma cell line (4T1) to model metastatic disease. Our data demonstrated that SZU101 was able to stimulate innate immune cells to release cytokines at the very high level compared with LPS at the same or lower concentration. Locally intratumoral SZU101 injection can elicit a systemic antitumor effect on murine breast tumor model. SZU101 affected the frequency of intratumoral immune cell infiltration, including the percentage of CD4+ and CD8+ increase, and the ratio of Tregs decrease. Our data reveal that the antitumor effect of SZU101 is associated with multiple mechanisms, inducing tumor‑specific immune response, activation of innate immune cells and modulation of the tumor microenvironment. PMID:26718332

  1. 4-Hydroxydocosahexaenoic acid, a potent peroxisome proliferator-activated receptor {gamma} agonist alleviates the symptoms of DSS-induced colitis

    SciTech Connect

    Yamamoto, Keiko; Ninomiya, Yuichi; Iseki, Mioko; Nakachi, Yutaka; Kanesaki-Yatsuka, Yukiko; Yamanoue, Yu; Itoh, Toshimasa; Nishii, Yasuho; Petrovsky, Nikolai; Okazaki, Yasushi

    2008-03-14

    (5E,7Z,10Z,13Z,16Z,19Z)-4-Hydroxy-5,7,10,13,16,19-docosahexaenoic acid (4-OHDHA) is a potential agonist of peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}) and antidiabetic agent as has been previously reported. As PPAR{gamma} agonists may also have anti-inflammatory functions, in this study, we investigated whether 4-OHDHA has an inhibitory effect on expression of inflammatory genes in vitro and whether 4-OHDHA could relieve the symptoms of dextran sodium sulfate (DSS)-induced colitis in a murine model of inflammatory bowel disease. 4-OHDHA inhibited production of nitric oxide and expression of a subset of inflammatory genes including inducible nitric oxide synthase (Nos2/iNOS) and interleukin 6 (Il6) by lipopolysaccharide (LPS)-activated macrophages. In addition, 4-OHDHA-treated mice when compared to control mice not receiving treatment recovered better from the weight loss caused by DSS-induced colitis. Changes in disease activity index (DAI) of 4-OHDHA-treated mice were also more favorable than for control mice and were comparable with mice treated with a typical anti-inflammatory-drug, 5-aminosalichylic acid (5-ASA). These results suggest that 4-OHDHA has potentially clinically useful anti-inflammatory effects mediated by suppression of inflammatory gene expression.

  2. Salicylic acid potentiates an agonist-dependent gain control that amplifies pathogen signals in the activation of defense mechanisms.

    PubMed Central

    Shirasu, K; Nakajima, H; Rajasekhar, V K; Dixon, R A; Lamb, C

    1997-01-01

    The phenylpropanoid-derived natural product salicylic acid (SA) plays a key role in disease resistance. However, SA administered in the absence of a pathogen is a paradoxically weak inductive signal, often requiring concentrations of 0.5 to 5 mM to induce acquired resistance or related defense mechanisms or to precondition signal systems. In contrast, endogenous SA accumulates to concentrations of < 70 microM at the site of attempted infection. Here, we show that although 10 to 100 microM SA had negligible effects when administered to soybean cell suspensions in the absence of a pathogen, physiological concentrations of SA markedly enhanced the induction of defense gene transcripts, H2O2 accumulation, and hypersensitive cell death by an avirulent strain of Pseudomonas syringae pv glycinea, with optimal effects being at approximately 50 microM. SA also synergistically enhanced H2O2 accumulation in response to the protein phosphatase type 2A inhibitor cantharidin in the absence of a pathogen. The synergistic effect of SA was potent, rapid, and insensitive to the protein synthesis inhibitor cycloheximide, and we conclude that SA stimulates an agonist-dependent gain control operating at an early step in the signal pathway for induction of the hypersensitive response. This fine control mechanism differs from previously described time-dependent, inductive coarse control mechanisms for SA action in the absence of a pathogen. Induction of H2O2 accumulation and hypersensitive cell death by avirulent P. s. glycinea was blocked by the phenylpropanoid synthesis inhibitor alpha-aminooxy-beta-phenylpropionic acid, and these responses could be rescued by exogenous SA. Because the agonist-dependent gain control operates at physiological levels of SA, we propose that rapid fine control signal amplification makes an important contribution to SA function in the induction of disease resistance mechanisms. PMID:9061956

  3. Discovery of tripeptide-derived multifunctional ligands possessing delta/mu opioid receptor agonist and neurokinin 1 receptor antagonist activities.

    PubMed

    Nair, Padma; Yamamoto, Takashi; Cowell, Scott; Kulkarni, Vinod; Moye, Sharif; Navratilova, Edita; Davis, Peg; Ma, Shou-Wu; Vanderah, Todd W; Lai, Josephine; Porreca, Frank; Hruby, Victor J

    2015-09-01

    Several bifunctional peptides were synthesized and characterized based on the pentapeptide-derived ligand NP30 (1: Tyr-DAla-Gly-Phe-Gly-Trp-O-[3',5'-Bzl(CF3)2]). Modification and truncation of amino acid residues were performed, and the tripeptide-derived ligand NP66 (11: Dmt-DAla-Trp-NH-[3',5'-(CF3)2-Bzl]) was obtained based on the overlapping pharmacophore concept. The Trp(3) residue of ligand 11 works as a message residue for both opioid and NK1 activities. The significance lies in the observation that the approach of appropriate truncation of peptide sequence could lead to a tripeptide-derived chimeric ligand with effective binding and functional activities for both mu and delta opioid and NK1 receptors with agonist activities at mu and delta opioid and antagonist activity at NK1 receptors, respectively. PMID:26212775

  4. Conicasterol E, a small heterodimer partner sparing farnesoid X receptor modulator endowed with a pregnane X receptor agonistic activity, from the marine sponge Theonella swinhoei.

    PubMed

    Sepe, Valentina; Ummarino, Raffaella; D'Auria, Maria Valeria; Chini, Maria Giovanna; Bifulco, Giuseppe; Renga, Barbara; D'Amore, Claudio; Debitus, Cécile; Fiorucci, Stefano; Zampella, Angela

    2012-01-12

    We report the isolation and pharmacological characterization of conicasterol E isolated from the marine sponge Theonella swinhoei. Pharmacological characterization of this steroid in comparison to CDCA, a natural FXR ligand, and 6-ECDCA, a synthetic FXR agonist generated by an improved synthetic strategy, and rifaximin, a potent PXR agonist, demonstrated that conicasterol E is an FXR modulator endowed with PXR agonistic activity. Conicasterol E induces the expression of genes involved in bile acids detoxification without effect on the expression of small heterodimer partner (SHP), thus sparing the expression of genes involved in bile acids biosynthesis. The relative positioning in the ligand binding domain of FXR, explored through docking calculations, demonstrated a different spatial arrangement for conicasterol E and pointed to the presence of simultaneous and efficient interactions with the receptor. In summary, conicasterol E represents a FXR modulator and PXR agonist that might hold utility in treatment of liver disorders. PMID:22126372

  5. Fish somatostatin sst3 receptor: comparison of radioligand and GTPgammaS binding, adenylate cyclase and phospholipase C activities reveals different agonist-dependent pharmacological signatures.

    PubMed

    Siehler, S; Nunn, C; Zupanc, G K H; Hoyer, D

    2005-01-01

    1 The fish somatostatin receptor 3 (fsst3) is one of the few somatostatin (SRIF) receptors cloned from a non-mammalian species so far. Here we extended our earlier characterization of this receptor by investigating the guanine nucleotide sensitivity of agonist radioligand binding at the fsst3 receptor recombinantly expressed in CCL39 (Chinese hamster lung fibroblast) cells. Further, we measured somatostatin (SRIF) and cortistatin (CST) analogues stimulated GTPgammaS binding, inhibition of forskolin-stimulated adenylate cyclase (FSAC) and stimulation of phospholipase C (PLC) activities. The present transductional data were then compared with previous radioligand binding and/or second messenger features determined for fsst3 and/or human SRIF receptors (hsst2, hsst3 and hsst5). 2 The GTP analogue guanylylimidodiphosphate (GppNHp) inhibited binding of [125I]CGP 23996 and [125I][Tyr3octreotide by 72 and 83% suggesting preferential labelling of G-protein-coupled fsst3 receptors. By contrast, [125I]LTT-SRIF28 and [125I][Tyr10]CST14 binding was rather GppNHp insensitive (42 and 35% inhibition) suggesting labelling of both coupled and non-coupled receptor states. These results might explain the apparent higher receptor densities determined in saturation experiments with [125I]LTT-SRIF28 and [125I][Tyr10]CST14 (4470 and 4030 fmol mg(-1)) compared with [125I]CGP 23996 and [125I][Tyr3]octreotide (3420 and 1520 fmol mg(-1)). 3 SRIF14 (10 microm)-stimulated specific [35S]GTPgammaS binding by three-fold; SRIF28 and octreotide displayed full agonism, whereas most other ligands displayed 60-80% intrinsic activity compared with SRIF14. SRIF14 and SRIF28 inhibited forskolin-stimulated AC (FSAC) activity by 60%; all tested ligands except BIM 23056 inhibited FSAC with comparable high intrinsic activities. SRIF14 stimulated PLC activity five- to six-fold, as determined by measuring total [3H] IP(x) accumulation; it was rather insensitive to pertussis toxin (PTX, 100 ng ml(-1), 21% inhibition), which suggests the G(q)-family proteins couple to PLC activity. SRIF14, SRIF28 and [Tyr10]CST14 showed full agonism at PLC, whereas all other ligands behaved as partial agonists (20-70% intrinsic activity). BIM 23056, which showed weak partial or no agonism, antagonized SRIF14-induced total [3H]-IP(x) production (pK(B) = 6.83), but failed to block competitively agonist-stimulated [35S]GTPgammaS binding or agonist-induced inhibition of FSAC activity. 4 Comparison of the pharmacological profiles of fsst3 receptors established in GTPgammaS binding, FSAC inhibition and PLC stimulation resulted in low correlations (r = 0.410-0.594). Both rank orders of potency and rank orders of relative efficacy varied in the three second messenger experiments. Significant, although variable correlations were obtained comparing GTPgammaS binding and inhibition of FSAC activity with previously reported affinity profiles of [125I]LTT-SRIF28, [125I][Tyr10]CST14, [125I]CGP 23996, [125I][Tyr3]octreotide (r = 0.75-0.83; 0.68-0.89). By contrast, the PLC stimulation and radioligand-binding profiles did not correlate. 5 Comparison of the functional data (GTPgammaS binding, FSAC inhibition, PLC stimulation) of fsst3 receptors with those of human sst2, sst3, sst5 receptors expressed in CCL39 cells resulted in highest correlation with the hsst5 receptor (r = 0.94, 0.97, 0.49) > hsst2 (0.80, 0.50, n.d.) > hsst3 (0.25, 0.19, 0.17). 6 In summary, fsst3 receptors expressed in CCL39 cells are involved in signalling cascades similar to those reported for mammalian SRIF receptors, suggesting SRIF receptors to be highly conserved in evolution. Binding and functional data showed highest similarity of fsst3 receptors with the human sst5 receptor subtype. Different affinities, receptor densities and GppNHp-sensitivities determined with the four radioligands (agonists) are assumed to results from ligand-specific states of the fsst3-ligand complex. The differences in the rank orders of potency and relative efficacy in the various signalling cascades may be explained by agonist-induced receptor trafficking. PMID:15659149

  6. Toll-like Receptor-8 Agonistic Activities in C2, C4, and C8 Modified Thiazolo[4,5-c]quinolines

    PubMed Central

    Kokatla, Hari Prasad; Yoo, Euna; Salunke, Deepak B.; Sil, Diptesh; Ng, Cameron F.; Balakrishna, Rajalakshmi; Malladi, Subbalakshmi S.; Fox, Lauren M.; David, Sunil A.

    2013-01-01

    Toll-like receptor (TLR)-8 agonists typified by the 2-alkylthiazolo[4,5-c]quinolin-4-amine (CL075) chemotype are uniquely potent in activating adaptive immune responses by inducing robust production of T helper 1-polarizing cytokines, suggesting that TLR8-active compounds could be promising candidate vaccine adjuvants, especially for neonatal vaccines. Alkylthiazoloquinolines with methyl, ethyl, propyl and butyl groups at C2 displayed comparable TLR8-agonistic potencies; activity diminished precipitously in the C2-pentyl compound, and higher homologues were inactive. The C2-butyl compound was unique in possessing substantial TLR7-agonistic activity. Analogues with branched alkyl groups at C2 displayed poor tolerance of terminal steric bulk. Virtually all modifications at C8 led to abrogation of agonistic activity. Alkylation on the C4-amine was not tolerated, whereas N-acyl analogues with short acyl groups (other than acetyl) retained TLR8 agonistic activity, but were substantially less water-soluble. Immunization in rabbits with a model subunit antigen adjuvanted with the lead C2-butyl thiazoloquinoline showed enhancements of antigen-specific antibody titers. PMID:23314908

  7. Activation of the gut calcium-sensing receptor by peptide agonists reduces rapid elevation of plasma glucose in response to oral glucose load in rats.

    PubMed

    Muramatsu, Maya; Hira, Tohru; Mitsunaga, Arimi; Sato, Eri; Nakajima, Shingo; Kitahara, Yoshiro; Eto, Yuzuru; Hara, Hiroshi

    2014-06-15

    The calcium-sensing receptor (CaSR) is expressed in various tissues, including the gastrointestinal tract. To investigate the role of gut CaSR on glycemic control, we examined whether single oral administration of CaSR agonist peptides affected the glycemic response in rats. Glucose tolerance tests were performed under oral or duodenal administration of various CaSR agonist peptides (?Glu-Cys, protamine, and poly-d-lysine hydrobromide) in conscious rats. Involvement of CaSR was determined by using a CaSR antagonist. Signaling pathways underlying CaSR agonist-modified glycemia were investigated using gut hormone receptor antagonists. The gastric emptying rate after the administration of CaSR agonist peptides was measured by the phenol red recovery method. Oral and duodenal administration of CaSR agonist peptides attenuated glycemic responses under the oral glucose tolerance test, but the administration of casein did not. The promotive effect on glucose tolerance was weakened by luminal pretreatment with a CaSR antagonist. Treatment with a 5-HT3 receptor antagonist partially diminished the glucose-lowering effect of peptides. Furthermore, the gastric emptying rate was decreased by duodenal administration of CaSR agonist peptides. These results demonstrate that activation of the gut CaSR by peptide agonists promotes glucose tolerance in conscious rats. 5-HT3 receptor and the delayed gastric emptying rate appear to be involved in the glucose-lowering effect of CaSR agonist peptides. Thus, activation of gut CaSR by dietary peptides reduces glycemic responses so that gut CaSR may be a potential target for the improvement of postprandial glycemia. PMID:24812056

  8. Potentiation of GABAA receptor activity by volatile anaesthetics is reduced by α5GABAA receptor-preferring inverse agonists

    PubMed Central

    Lecker, I.; Yin, Y.; Wang, D. S.; Orser, B. A.

    2013-01-01

    Background Animal studies have shown that memory deficits in the early post-anaesthetic period can be prevented by pre-treatment with an inverse agonist that preferentially inhibits α5 subunit-containing γ-aminobutyric acid type A (α5GABAA) receptors. The goal of this in vitro study was to determine whether inverse agonists that inhibit α5GABAA receptors reduce anaesthetic potentiation of GABAA receptor activity. Methods Cultures of hippocampal neurones were prepared from Swiss white mice, wild-type mice (genetic background C57BL/6J and Sv129Ev) and α5GABAA receptor null mutant (Gabra5−/−) mice. Whole-cell voltage clamp techniques were used to study the effects of the α5GABAA receptor-preferring inverse agonists L-655,708 and MRK-016 on anaesthetic potentiation of GABA-evoked currents. Results L-655,708 (50 nM) reduced sevoflurane potentiation of GABA-evoked current in wild-type neurones but not Gabra5−/− neurones, and produced a rightward shift in the sevoflurane concentration–response plot [sevoflurane EC50: 1.9 (0.1) mM; sevoflurane+L-655,708 EC50: 2.4 (0.2) mM, P<0.05]. Similarly, L-655,708 (50 nM) reduced isoflurane potentiation of GABA-evoked current [isoflurane: 4.0 (0.6) pA pF−1; isoflurane+L-655,708: 3.1 (0.5) pA pF−1, P<0.01]. MRK-016 also reduced sevoflurane and isoflurane enhancement of GABA-evoked current [sevoflurane: 1.5 (0.1) pA pF−1; sevoflurane+MRK-016 (10 nM): 1.2 (0.1) pA pF−1, P<0.05; isoflurane: 3.5 (0.3) pA pF−1; isoflurane+MRK-016 (1 nM): 2.9 (0.2) pA pF−1, P<0.05]. Conclusions L-655,708 and MRK-016 reduced the potentiation by inhaled anaesthetics of GABAA receptor activated by a low concentration of GABA. Future studies are required to determine whether this effect contributes to the memory preserving properties of inverse agonists after anaesthesia. PMID:23535829

  9. Identification of Isosilybin A from Milk Thistle Seeds as an Agonist of Peroxisome Proliferator-Activated Receptor Gamma

    PubMed Central

    2014-01-01

    Peroxisome proliferator-activated receptor gamma (PPARγ) is a key regulator of glucose and lipid metabolism. Agonists of this nuclear receptor are used in the treatment of type 2 diabetes and are also studied as a potential treatment of other metabolic diseases, including nonalcoholic fatty liver disease. Silymarin, a concentrated phenolic mixture from milk thistle (Silybum marianum) seeds, is used widely as a supportive agent in the treatment of a variety of liver diseases. In this study, the PPARγ activation potential of silymarin and its main constituents was investigated. Isosilybin A (3) caused transactivation of a PPARγ-dependent luciferase reporter in a concentration-dependent manner. This effect could be reversed upon co-treatment with the PPARγ antagonist T0070907. In silico docking studies suggested a binding mode for 3 distinct from that of the inactive silymarin constituents, with one additional hydrogen bond to Ser342 in the entrance region of the ligand-binding domain of the receptor. Hence, isosilybin A (3) has been identified as the first flavonolignan PPARγ agonist, suggesting its further investigation as a modulator of this nuclear receptor. PMID:24597776

  10. [Dmt1]DALDA analogues with enhanced μ opioid agonist potency and with a mixed μ/κ opioid activity profile

    PubMed Central

    Bai, Longxiang; Li, Ziyuan; Chen, Jiajia; Chung, Nga N.; Wilkes, Brian C.; Li, Tingyou; Schiller, Peter W.

    2014-01-01

    Analogues of [Dmt1]DALDA (H-Dmt-D-Arg-Phe-Lys-NH2; Dmt = 2′,6′-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity, were prepared by replacing Phe3 with various 2′,6′-dialkylated Phe analogues, including 2′,6′-dimethylphenylalanine (Dmp), 2′4′,6′-trimethylphenylalanine (Tmp), 2′-isopropyl-6′-methylphenylalanine (Imp) and 2′-ethyl-6′-methylphenylalanine (Emp), or with the bulky amino acids 3′-(1-naphthyl)alanine (1-Nal), 3′-(2-naphthyl)alanine (2-Nal) or Trp. Several compounds showed significantly increased μ agonist potency, retained μ receptor selectivity and are of interest as drug candidates for neuropathic pain treatment. Surprisingly, the Dmp3-, Imp3-, Emp3- and 1-Nal3-containing analogues showed much increased κ receptor binding affinity and had mixed μ/κ properties. In these cases, molecular dynamics studies indicated conformational preorganization of the unbound peptide ligands due to rotational restriction around the Cβ-Cγ bond of the Xxx3 residue, in correlation with the observed κ receptor binding enhancement. Compounds with a mixed μ/κ opioid activity profile are known to have therapeutic potential for treatment of cocaine abuse. PMID:24602401

  11. Peroxisome proliferator-activated receptor alpha-retinoid X receptor agonists induce beta-cell protection against palmitate toxicity.

    PubMed

    Hellemans, Karine; Kerckhofs, Karen; Hannaert, Jean-Claude; Martens, Geert; Van Veldhoven, Paul; Pipeleers, Daniel

    2007-12-01

    Fatty acids can stimulate the secretory activity of insulin-producing beta-cells. At elevated concentrations, they can also be toxic to isolated beta-cells. This toxicity varies inversely with the cellular ability to accumulate neutral lipids in the cytoplasm. To further examine whether cytoprotection can be achieved by decreasing cytoplasmic levels of free acyl moieties, we investigated whether palmitate toxicity is also lowered by stimulating its beta-oxidation. Lower rates of palmitate-induced beta-cell death were measured in the presence of L-carnitine as well as after addition of peroxisome proliferator-activated receptor alpha (PPARalpha) agonists, conditions leading to increased palmitate oxidation. In contrast, inhibition of mitochondrial beta-oxidation by etomoxir increased palmitate toxicity. A combination of PPARalpha and retinoid X receptor (RXR) agonists acted synergistically and led to complete protection; this was associated with enhanced expression levels of genes involved in mitochondrial and peroxisomal beta-oxidation, lipid metabolism, and peroxisome proliferation. PPARalpha-RXR protection was abolished by the carnitine palmitoyl transferase 1 inhibitor etomoxir. These observations indicate that PPARalpha and RXR regulate beta-cell susceptibility to long-chain fatty acid toxicity by increasing the rates of beta-oxidation and by involving peroxisomes in fatty acid metabolism. PMID:17970749

  12. Synthesis, Pharmacological Characterization, and Structure–Activity Relationship Studies of Small Molecular Agonists for the Orphan GPR88 Receptor

    PubMed Central

    2014-01-01

    GPR88 is an orphan G-protein-coupled receptor (GPCR) enriched in the striatum. Genetic deletion and gene expression studies have suggested that GPR88 plays an important role in the regulation of striatal functions and is implicated in psychiatric disorders. The signal transduction pathway and receptor functions of GPR88, however, are still largely unknown due to the lack of endogenous and synthetic ligands. In this paper, we report the synthesis of a GPR88 agonist 2-PCCA and its pure diastereomers, which were functionally characterized in both transiently and stably expressing GPR88 HEK293 cells. 2-PCCA inhibited isoproterenol-stimulated cAMP accumulation in a concentration-dependent manner in cells expressing GPR88 but not in the control cells, suggesting that the observed cAMP inhibition is mediated through GPR88 and that GPR88 is coupled to Gαi. 2-PCCA did not induce calcium mobilization in GPR88 cells, indicating no Gαq-mediated response. A structure–activity relationship (SAR) study of 2-PCCA was also conducted to explore the key structural features for GPR88 agonist activity. PMID:24793972

  13. Anticonvulsant activity of melatonin, but not melatonin receptor agonists Neu-P11 and Neu-P67, in mice.

    PubMed

    Mosińska, Paula; Socała, Katarzyna; Nieoczym, Dorota; Laudon, Moshe; Storr, Martin; Fichna, Jakub; Wlaź, Piotr

    2016-07-01

    The anticonvulsant activity of melatonin (MLT) have been tested in several in vivo models and against different convulsive stimuli. Although MLT exerts high affinity towards melatonin receptors (MTs), the potential usefulness in the treatment of epilepsy is limited mainly due to its short half-life. Therefore, the purpose of the present study was to compare the anticonvulsant properties of novel MT agonists Neu-P11 and Neu-P67 with MLT in mice. The anticonvulsant activity of tested compounds was evaluated in pentylenetetrazole-(PTZ) and electrically-induced convulsions. The effect of studied compounds on motor coordination and skeletal muscular strength in mice was assessed in the chimney test and grip test, respectively. The locomotor activity after administration of the tested compounds was also evaluated. In the MEST and 6Hz tests, only MLT (50 and 100mg/kg, i.p.) significantly increased the seizure threshold. The i.p. administration of MLT (100mg/kg) and Neu-P67 (200mg/kg) resulted in a significantly elevated PTZ seizure threshold for forelimbs tonus. The compounds did not affect muscle strength. No alterations in motor coordination were noted. However, the locomotor activity was significantly decreased after administration of all tested compounds. Our study confirms the anticonvulsant potency of MLT and shows that novel synthetic MT agonists Neu-P11 and Neu-P67 have no effect on epileptic seizures in mice. Our data suggest that the activation of MT can be used in the treatment of seizures, but further pharmacological characterization is needed to understand the anticonvulsant activity of MLT and to design efficient MT-targeting antiepileptic drugs. PMID:27016427

  14. The QBO and weak external forcing by solar activity: A three dimensional model study

    NASA Technical Reports Server (NTRS)

    Dameris, M.; Ebel, A.

    1989-01-01

    A better understanding is attempted of the physical mechanisms leading to significant correlations between oscillations in the lower and middle stratosphere and solar variability associated with the sun's rotation. A global 3-d mechanistic model of the middle atmosphere is employed to investigate the effects of minor artificially induced perturbations. The aim is to explore the physical mechanisms of the dynamical response especially of the stratosphere to weak external forcing as it may result from UV flux changes due to solar rotation. First results of numerical experiments dealing about the external forcing of the middle atmosphere by solar activity were presented elsewhere. Different numerical studies regarding the excitation and propagation of weak perturbations have been continued since then. The model calculations presented are made to investigate the influence of the quasi-biennial oscillation (QBO) on the dynamical response of the middle atmosphere to weak perturbations by employing different initial wind fields which represent the west and east phase of the QBO.

  15. Functional Impact of Allosteric Agonist Activity of Selective Positive Allosteric Modulators of Metabotropic Glutamate Receptor Subtype 5 in Regulating Central Nervous System Function

    PubMed Central

    Noetzel, Meredith J.; Rook, Jerri M.; Vinson, Paige N.; Cho, Hyekyung P.; Days, Emily; Zhou, Y.; Rodriguez, Alice L.; Lavreysen, Hilde; Stauffer, Shaun R.; Niswender, Colleen M.; Xiang, Zixiu; Daniels, J. Scott; Jones, Carrie K.; Lindsley, Craig W.; Weaver, C. David

    2012-01-01

    Positive allosteric modulators (PAMs) of metabotropic glutamate receptor subtype 5 (mGlu5) have emerged as an exciting new approach for the treatment of schizophrenia and other central nervous system (CNS) disorders. Of interest, some mGlu5 PAMs act as pure PAMs, only potentiating mGlu5 responses to glutamate whereas others [allosteric agonists coupled with PAM activity (ago-PAMs)] potentiate responses to glutamate and have intrinsic allosteric agonist activity in mGlu5-expressing cell lines. All mGlu5 PAMs previously shown to have efficacy in animal models act as ago-PAMs in cell lines, raising the possibility that allosteric agonist activity is critical for in vivo efficacy. We have now optimized novel mGlu5 pure PAMs that are devoid of detectable agonist activity and structurally related mGlu5 ago-PAMs that activate mGlu5 alone in cell lines. Studies of mGlu5 PAMs in cell lines revealed that ago-PAM activity is dependent on levels of mGlu5 receptor expression in human embryonic kidney 293 cells, whereas PAM potency is relatively unaffected by levels of receptor expression. Furthermore, ago-PAMs have no agonist activity in the native systems tested, including cortical astrocytes and subthalamic nucleus neurons and in measures of long-term depression at the hippocampal Schaffer collateral-CA1 synapse. Finally, studies with pure PAMs and ago-PAMs chemically optimized to provide comparable CNS exposure revealed that both classes of mGlu5 PAMs have similar efficacy in a rodent model predictive of antipsychotic activity. These data suggest that the level of receptor expression influences the ability of mGlu5 PAMs to act as allosteric agonists in vitro and that ago-PAM activity observed in cell-based assays may not be important for in vivo efficacy. PMID:22021324

  16. Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist inhibits collagen synthesis in human hypertrophic scar fibroblasts by targeting Smad3 via miR-145

    SciTech Connect

    Zhu, Hua-Yu; Li, Chao; Zheng, Zhao; Zhou, Qin; Guan, Hao; Su, Lin-Lin; Han, Jun-Tao; Zhu, Xiong-Xiang; Wang, Shu-yue; Li, Jun Hu, Da-Hai

    2015-03-27

    The transcription factor peroxisome proliferator-activated receptor-γ (PPAR-γ) functions to regulate cell differentiation and lipid metabolism. Recently, its agonist has been documented to regulate extracellular matrix production in human dermal fibroblasts. This study explored the underlying molecular mechanisms and gene interactions in hypertrophic scar fibroblasts (HSFBs) in vitro. HSFBs were cultured and treated with or without PPAR-γ agonist or antagonist for gene expression. Bioinformatical analysis predicted that miR-145 could target Smad3 expression. Luciferase assay was used to confirm such an interaction. The data showed that PPAR-γ agonist troglitazone suppressed expression of Smad3 and Col1 in HSFBs. PPAR-γ agonist induced miR-145 at the gene transcriptional level, which in turn inhibited Smad3 expression and Col1 level in HSFBs. Furthermore, ELISA data showed that Col1 level in HSFBs was controlled by a feedback regulation mechanism involved in PPAR-γ agonist and antagonist-regulated expression of miR-145 and Smad3 in HSFBs. These findings indicate that PPAR-γ-miR-145-Smad3 axis plays a role in regulation of collagen synthesis in HSFBs. - Highlights: • PPAR-γ agonist inhibits collagen synthesis in HSFBs. • Smad3 and type I collagen expression are decreased by PPAR-γ agonist. • miR-145 expression is increased by PPAR-γ agonist in HSFBs. • Increased miR-145 inhibits collagen synthesis by targeting Smad3. • miR-145 regulates collagen synthesis.

  17. A new perspective for schizophrenia: TAAR1 agonists reveal antipsychotic- and antidepressant-like activity, improve cognition and control body weight.

    PubMed

    Revel, F G; Moreau, J-L; Pouzet, B; Mory, R; Bradaia, A; Buchy, D; Metzler, V; Chaboz, S; Groebke Zbinden, K; Galley, G; Norcross, R D; Tuerck, D; Bruns, A; Morairty, S R; Kilduff, T S; Wallace, T L; Risterucci, C; Wettstein, J G; Hoener, M C

    2013-05-01

    Schizophrenia is a chronic, severe and highly complex mental illness. Current treatments manage the positive symptoms, yet have minimal effects on the negative and cognitive symptoms, two prominent features of the disease with critical impact on the long-term morbidity. In addition, antipsychotic treatments trigger serious side effects that precipitate treatment discontinuation. Here, we show that activation of the trace amine-associated receptor 1 (TAAR1), a modulator of monoaminergic neurotransmission, represents a novel therapeutic option. In rodents, activation of TAAR1 by two novel and pharmacologically distinct compounds, the full agonist RO5256390 and the partial agonist RO5263397, blocks psychostimulant-induced hyperactivity and produces a brain activation pattern reminiscent of the antipsychotic drug olanzapine, suggesting antipsychotic-like properties. TAAR1 agonists do not induce catalepsy or weight gain; RO5263397 even reduced haloperidol-induced catalepsy and prevented olanzapine from increasing body weight and fat accumulation. Finally, TAAR1 activation promotes vigilance in rats and shows pro-cognitive and antidepressant-like properties in rodent and primate models. These data suggest that TAAR1 agonists may provide a novel and differentiated treatment of schizophrenia as compared with current medication standards: TAAR1 agonists may improve not only the positive symptoms but also the negative symptoms and cognitive deficits, without causing adverse effects such as motor impairments or weight gain. PMID:22641180

  18. Involvement of Nitric Oxide on Calcium Mobilization and Arachidonic Acid Pathway Activation during Platelet Aggregation with different aggregating agonists

    PubMed Central

    Banerjee, Debipriya; Mazumder, Sahana; Kumar Sinha, Asru

    2016-01-01

    Platelet aggregation by different aggregating agonists is essential in the normal blood coagulation process, the excess of which caused acute coronary syndrome (ACS). In all cases, the activation of arachidonic acid by cycloxygenase was needed for the synthesis of thromboxane A2 (TXA2) but the mechanism of arachidonic acid release in platelets remains obscure. Studies were conducted to determine the role of nitric oxide (NO), if any, on the release of arachidonic acid in platelets. The cytosolic Ca2+ was visualized and quantitated by fluorescent spectroscopy by using QUIN-2. NO was measured by methemoglobin method. Arachidonic acid was determined by HPLC. TXA2 was measured as ThromboxaneB2 (TXB2) by ELISA. Treatment of platelets in platelet-rich plasma (PRP) with different aggregating agents resulted in the inhibition of nitric oxide synthase (NOS) which inhibited the production of NO synthesis and increased TXA2 synthesis. Furthermore, the treatment of washed PRP with different platelet aggregating agents resulted in the increase of [Ca2+] in nM ranges. In contrast, the pre-treatment of washed PRP with aspirin increased platelet NO level and inhibited the Ca2+ mobilization and TXA2 synthesis. These results indicated that the aggregation of platelets by different aggregating agonists was caused by the cytosolic Ca2+ mobilization due to the inhibition of NOS.

  19. An A2B Adenosine Receptor Agonist Promotes Th17 Autoimmune Responses in Experimental Autoimmune Uveitis (EAU) via Dendritic Cell Activation

    PubMed Central

    Chen, Mingjiazi; Liang, Dongchun; Zuo, Aijun; Shao, Hui; Kaplan, Henry J.; Sun, Deming

    2015-01-01

    We have recently reported that, although adenosine receptor (AR) agonists have a suppressive effect on Th1 autoreactive T cells, their effect on Th17 autoreactive T cells and ?? T cells is stimulatory and this effect is mainly mediated via A2A adenosine receptors (A2ARs). In this study, we further demonstrate that treatment of C57BL/6 (B6) mice with a selective A2B adenosine receptor (A2BR) agonist greatly enhanced the development of experimental autoimmune uveitis (EAU), whereas treatment with an A2BR antagonist significantly ameliorated severity of EAU. The A2BR agonist-treated mice showed augmented Th17, but not Th1, responses. Mechanistic studies showed that the A2BR agonist-induced enhancement of the Th17 response was significantly lower when TCR-?-/- mice received the same treatment and that transfer of ?? T cells into TCR-?-/- mice partially restored this effect. We also showed that dendritic cells (DCs) from A2BR agonist-treated mice showed a significantly increased ability to activate ?? T cells and Th17 autoreactive T cells. Thus, our previous studies have shown that, in EAU, activated ?? T cells possess greatly increased ability to enhance Th17 autoimmune responses. In the present study, we showed that exposure of DCs to A2BR agonist facilitated ?? T cell activation, leading to augmented Th17 responses and progressive EAU development. Our results further support our previous finding that AR agonists have distinct effects on Th1 and Th17 autoimmune responses. PMID:26147733

  20. Pharmacological profile of the abeorphine 201-678, a potent orally active and long lasting dopamine agonist

    SciTech Connect

    Jaton, A.L.; Giger, R.K.A.; Vigouret, J.M.; Enz, A.; Frick, W.; Closse, A.; Markstein, R.

    1986-01-13

    The central dopaminergic effects of an abeorphine derivative 201-678 were compared to those of apomorphine and bromocriptine in different model systems. After oral administration, this compound induced contralateral turning in rats with 6-hydroxydopamine induced nigral lesions and exhibited strong anti-akinetic properties in rats with 6-hydroxydopamine induced hypothalamic lesions. It decreased dopamine metabolism in striatum and cortex, but did not modify noradrenaline and serotonin metabolism in the rat brain. 201-678 counteracted the in vivo increase of tyrosine hydroxylase activity induced by ..gamma..-butyrolactone. In vitro it stimulated DA-sensitive adenylate cyclase and inhibited acetylcholine release from rat striatal slices. This compound had high affinity for /sup 3/H-dopamine and /sup 3/H-clonidine binding sites. These results indicate that 201-678 is a potent, orally active dopamine agonist with a long duration of action. Furthermore it appears more selective than other dopaminergic drugs. 29 references, 5 figures, 3 tables.

  1. Effect of peroxisome proliferator-activated receptor-alpha agonist (bezafibrate) on gastric secretion and gastric cytoprotection in rats.

    PubMed

    Pathak, Rahul; Asad, Mohammed; Hrishikeshavan, H Jagannath; Prasad, Satya

    2007-06-01

    The effect of peroxisome proliferator-activated receptor-alpha (PPAR-alpha) on gastric secretion and gastric cytoprotection was evaluated using five different models of gastric ulcers: acetic acid-induced chronic gastric ulcers, pylorus ligation, ethanol-induced, indomethacin-induced and ischemia-reperfusion-induced gastric ulcers. Bezafibrate, a PPAR-alpha agonist was administered at two different doses of 10 and 100 mg/kg body weight intraperitoneanally. Both doses of bezafibrate showed significant antiulcer effect in ethanol-induced, indomethacin-induced and pylorus ligation-induced gastric ulcers. Bezafibrate increased healing of ulcer in acetic acid-induced chronic gastric ulcer model. Both doses were also effective in preventing gastric lesions induced by ischemia-reperfusion. It was concluded that PPAR-alpha activation increases healing of gastric ulcers and also prevents development of gastric ulcers in rats. PMID:17521298

  2. Weak activity of UDP-glucuronosyltransferase toward Bisphenol analogs in mouse perinatal development

    PubMed Central

    YABUSAKI, Risa; IWANO, Hidetomo; TSUSHIMA, Sumito; KOIKE, Nanako; OHTANI, Naoko; TANEMURA, Kentaro; INOUE, Hiroki; YOKOTA, Hiroshi

    2015-01-01

    Bisphenol A (BPA) is a widely used industrial chemical that disrupts endocrine function. BPA is an endocrine disrupting chemical (EDC) that has been demonstrated to affect reproductive organ development, brain development, metabolic disease and post-natal behavior. Accordingly, Bisphenol analogs, Bisphenol F (BPF, bis (4-hydroxyphenyl) methane) and Bisphenol AF (BPAF, 4,4-hexafluoroisopropylidene) diphenol) are used as replacements for BPA. BPA is mainly metabolized by UDP-glucuronosyltransferase (UGT), UGT2B1, but this effective metabolizing system is weak in the fetus. In the present study, we demonstrated that hepatic UGT activity toward BPAF was very weak, in comparison with BPA and BPF, in the fetus, pups and dams. Conversely, hepatic UGT activity toward BPF was very weak in the fetus and newborn pups, and was increased to the same level as BPA post-partum. In conclusion, BPAF possibly tends to accumulate in the fetus, because of weak metabolism during the perinatal period, suggesting that the metabolism of individual Bisphenol analogs requires assessment to properly gauge their risks. PMID:26074487

  3. Nicotine enhances murine airway contractile responses to kinin receptor agonists via activation of JNK- and PDE4-related intracellular pathways

    PubMed Central

    2010-01-01

    Background Nicotine plays an important role in cigarette-smoke-associated airway disease. The present study was designed to examine if nicotine could induce airway hyperresponsiveness through kinin receptors, and if so, explore the underlying mechanisms involved. Methods Murine tracheal segments were cultured for 1, 2 or 4 days in serum-free DMEM medium in presence of nicotine (1 and 10 μM) or vehicle (DMSO). Contractile responses induced by kinin B1 receptor agonist, des-Arg9-bradykinin, and B2 receptor agonist, bradykinin, were monitored with myographs. The B1 and B2 receptor mRNA expressions were semi-quantified using real-time PCR and their corresponding protein expressions assessed with confocal-microscopy-based immunohistochemistry. Various pharmacological inhibitors were used for studying intracellular signaling pathways. Results Four days of organ culture with nicotine concentration-dependently increased kinin B1 and B2 receptor-mediated airway contractions, without altering the kinin receptor-mediated relaxations. No such increase was seen at day 1 or day 2. The airway contractile responses to 5-HT, acetylcholine and endothelin receptor agonists remained unaffected by nicotine. Two different neuronal nicotinic receptor antagonists MG624 and hexamethonium blocked the nicotine-induced effects. The enhanced contractile responses were accompanied by increased mRNA and protein expression for both kinin receptors, suggesting the involvement of transcriptional mechanisms. Confocal-microscopy-based immunohistochemistry showed that 4 days of nicotine treatment induced activation (phosphorylation) of c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase 1 and 2 (ERK1/2) and p38. Inhibition of JNK with its specific inhibitor SP600125 abolished the nicotine-induced effects on kinin receptor-mediated contractions and reverted the enhanced receptor mRNA expression. Administration of phosphodiesterase inhibitors (YM976 and theophylline), glucocorticoid (dexamethasone) or adenylcyclase activator (forskolin) suppressed the nicotine-enhanced airway contractile response to des-Arg9-bradykinin and bradykinin. Conclusions Nicotine induces airway hyperresponsiveness via transcriptional up-regulation of airway kinin B1 and B2 receptors, an effect mediated via neuronal nicotinic receptors. The underlying molecular mechanisms involve activation of JNK- and PDE4-mediated intracellular inflammatory signal pathways. Our results might be relevant to active and passive smokers suffering from airway hyperresponsiveness, and suggest new therapeutic targets for the treatment of smoke-associated airway disease. PMID:20113502

  4. Effects of nicotinic receptor agonists on bladder afferent nerve activity in an in vitro bladder-pelvic nerve preparation.

    PubMed

    Yu, Yongbei; Daugherty, Stephanie L; de Groat, William C

    2016-04-15

    Effects of nicotinic receptor agonists (epibatidine and nicotine) on mechano-sensitive bladder afferent nerve (MS-BAN) activity were studied in an in vitro bladder-pelvic afferent nerve preparation. MS-BAN activity was induced by isotonic distention of the bladder at pressures of 10-40cmH2O. The effect of epibatidine varied according to the concentration, route of administration and the intravesical pressure stimulus. Epibatidine (300-500nM) administered in the perfusate to the serosal surface of the bladder decreased distension evoked afferent firing by 30-50% depending on the bladder pressure. However these concentrations also produced an immediate increase in tonic afferent firing in the empty bladder. Lower concentrations (50-100nM) elicited weaker and more variable effects. The inhibitory effects were blocked by bath application of mecamylamine (150µM) a nicotinic receptor antagonist. Bath application of nicotine (20µM) elicited similar effects. Intravesical administration of epibatidine (500nM) significantly increased MS-BAN firing by 15-30%; while lower concentrations (200-300nM) were ineffective. This facilitatory effect of epibatidine was blocked by intravesical administration of mecamylamine (250µM). Electrical stimulation on the surface of the bladder elicited action potentials (AP) in BAN. Bath application of epibatidine (300nM) or nicotine (20µM) did not change either the voltage threshold or the area of evoked AP. These results indicate that nicotinic agonists: (1) enhance MS-BAN activity originating at afferent receptors near the urothelium, (2) inhibit MS-BAN activity originating at afferent receptors located at other sites in the bladder, (3) directly excite unidentified afferents, (4) do not alter afferent axonal excitability. PMID:26876739

  5. The hydrophobic tryptic core of the beta-adrenergic receptor retains Gs regulatory activity in response to agonists and thiols.

    PubMed

    Rubenstein, R C; Wong, S K; Ross, E M

    1987-12-01

    The function of structural domains of the beta-adrenergic receptor were probed by studying the ability of tryptic fragments of the receptor to catalyze the binding of guanosine-5'-O-(3-thiotriphosphate (GTP gamma S) to the GTP-binding regulatory protein, Gs. beta-Adrenergic receptor purified from turkey erythrocytes was treated with trypsin under nondenaturing conditions. Such treatment decreased beta-adrenergic ligand binding activity by only 15-25%. Active components of the limit digest were repurified by affinity chromatography on alprenolol-agarose and then reconstituted with purified Gs into unilamellar phospholipid vesicles. After reconstitution, the proteolyzed receptor was able to catalyze agonist-stimulated binding of GTP gamma S to Gs at a rate and extent equivalent to that of the nonproteolyzed receptor. The proteolyzed receptor was also partially activated upon reduction by dithiothreitol, as previously reported for the intact receptor (Pedersen, S.E., and Ross, E.M. (1985) J. Biol. Chem. 260, 14150-14157). The repurified, active tryptic digest contained two detectable peptides. One, of approximately 2 X 10(4) Da, contained either four or five of the amino-terminal membrane-spanning domains plus the intervening hydrophilic loops but not the amino-terminal extracellular, glycosylated peptide. The second, of 9,000-10,000 Da, was composed essentially of the two carboxyl-terminal membrane-spanning domains and the intervening extracellular, hydrophilic loop. These data indicate that most of the large intracellular hydrophilic loop and the hydrophilic, carboxyl-terminal region of the receptor are not necessary for the agonist-stimulated regulation of Gs. PMID:2890639

  6. Significant Correlation between TLR2 Agonist Activity and TNF-α Induction in J774.A1 Macrophage Cells by Different Medicinal Mushroom Products.

    PubMed

    Coy, Catherine; Standish, Leanna J; Bender, Geoff; Lu, Hailing

    2015-01-01

    In the US market, there is a variety of mushroom preparations available, even within the same species of mushroom. Nonetheless, little is known about whether species or the various extraction methods affect biological activity and potency of the immune modulatory activity of mushroom extracts. After discovering that protein-bound polysaccharide-K, a hot water extract from Trametes versicolor, was a potent Toll-like receptor (TLR)-2 agonist that stimulates both innate and adaptive immunity, this study was initiated to evaluate whether other medicinal mushroom products also have TLR2 agonist activity and immune-enhancing potential as measured by the induction of tumor necrosis factor (TNF)-α in J774.A1 murine macrophage cells. Furthermore, the products were divided by extraction method and species to determine whether these factors affect their immunomodulatory activity. The results showed that the majority (75%) of mushroom products tested had TLR2 agonist activity and that there was a significant correlation between TLR2 agonist activity and TNF-α induction potential in the mushroom products analyzed. In addition, the data demonstrated that hot water mushroom extracts are more potent than ground mushroom products in activating TLR2 and inducing TNF-α. These data provide evidence that extraction methods may affect the biological activity of mushroom products; thus, further studies are warranted to investigate the structural differences between various mushroom products. PMID:26559858

  7. Antagonizing effect of protein kinase C activation on the mu-opioid agonist-induced inhibition of high voltage-activated calcium current in rat periaqueductal gray neuron.

    PubMed

    Cho, Y W; Han, S H; Min, B I; Rhee, J S; Akaike, N

    2001-10-19

    Opioids have been thought to induce analgesia by activating the descending pain control system, especially at the level of periaqueductal gray, and regulate the neurotransmitter release through the inhibition of calcium channel. In the present study, the modulatory effects of protein kinase C and protein kinase A on the mu-opioid agonist-induced inhibition of the high-voltage activated calcium current were examined in the acutely dissociated rat periaqueductal gray neurons with the nystatin-perforated patch-clamp technique. Among 505 neurons tested, the barium current passing through the high-voltage activated calcium channels of 172 neurons (34%) were inhibited by 32+/-3% with the application of an mu-opioid agonist, [D-Ala(2),N-MePhe(4),Gly(5)-ol]-enkephalin (DAMGO, 1 microM). The barium currents itself and the DAMGO-induced inhibitory effects were not affected by the application of either an adenylate cyclase activator (forskolin, 1 microM) or a protein kinase inhibitor (staurosporin, 10 nM) for 2 min. The DAMGO inhibition was completely and irreversibly antagonized by the application of a protein kinase C activator, phorbol-12-myristate-13-acetate (PMA, 1 microM) for 2 min without any alteration of the barium current itself. However, the antagonizing effect of PMA was completely abolished by the application of 10 nM staurosporin for 2 min. After then, PMA did not show the antagonizing effect any more. Inversely, when staurosporin was applied before PMA, the antagonizing effect of PMA was also not shown. These results demonstrate that the mu-opioid agonist-induced inhibition of the periaqueductal gray neuronal high-voltage activated calcium current can be antagonized by protein kinase C activation. This finding may provide us a significant clue to understand the action mechanism of opioid-induced analgesia in the periaqueductal gray. PMID:11597591

  8. Anti-kindling Effect of Bezafibrate, a Peroxisome Proliferator-activated Receptors Alpha Agonist, in Pentylenetetrazole Induced Kindling Seizure Model

    PubMed Central

    Saha, Lekha; Bhandari, Swati; Bhatia, Alka; Banerjee, Dibyajyoti; Chakrabarti, Amitava

    2014-01-01

    Background and Purpose: Studies in the animals suggested that Peroxisome proliferators activated receptors (PPARs) may be involved in seizure control and selective agonists of PPAR α or PPAR γ raise seizure thresholds. The present study was contemplated with the aim of evaluating the anti kindling effects and the mechanism of bezafibrate, a Peroxisome proliferator-activated receptors α (PPAR-α) agonist in pentylenetetrazole (PTZ) induced kindling model of seizures in rats. Methods: In a PTZ kindled Wistar rat model, different doses of bezafibrate (100 mg/kg, 200 mg/kg and 300 mg/kg) were administered intraperitoneally 30 minutes before the PTZ injection. The PTZ injection was given on alternate day till the animal became fully kindled or till 10 weeks. The parameters measured were the latency to develop kindling and incidence of kindling, histopathological study of hippocampus, hippocampal lipid peroxidation studies, serum neuron specific enolase, and hippocampal DNA fragmentation study. Results: In this study, bezafibrate significantly reduced the incidence of kindling in PTZ treated rats and exhibited a marked prolongation in the latencies to seizures. In the present study bezafibrate decreased the thiobarbituric acid-reactive substance i.e. Malondialdehyde levels, increased the reduced glutathione levels, catalase and superoxide dismutase activity in the brain. This added to its additional neuroprotective effects. Bezafibrate also reduced the neuronal damage and apoptosis in hippocampal area of the brain. Therefore bezafibrate exerted anticonvulsant properties in PTZ induced kindling model in rats. Conclusions: These findings may provide insights into the understanding of the mechanism of bezafibrate as an anti kindling agent and could offer a useful support to the basic antiepileptic therapy in preventing the development of PTZ induced seizures, suggesting its potential for therapeutic applications in temporal lobe epilepsy. PMID:25625088

  9. Metabolic Profiling of Chicken Embryos Exposed to Perfluorooctanoic Acid (PFOA) and Agonists to Peroxisome Proliferator-Activated Receptors

    PubMed Central

    Mattsson, Anna; Kärrman, Anna; Pinto, Rui; Brunström, Björn

    2015-01-01

    Untargeted metabolic profiling of body fluids in experimental animals and humans exposed to chemicals may reveal early signs of toxicity and indicate toxicity pathways. Avian embryos develop separately from their mothers, which gives unique possibilities to study effects of chemicals during embryo development with minimal confounding factors from the mother. In this study we explored blood plasma and allantoic fluid from chicken embryos as matrices for revealing metabolic changes caused by exposure to chemicals during embryonic development. Embryos were exposed via egg injection on day 7 to the environmental pollutant perfluorooctanoic acid (PFOA), and effects on the metabolic profile on day 12 were compared with those caused by GW7647 and rosiglitazone, which are selective agonists to peroxisome-proliferator activated receptor α (PPARα) and PPARγ, respectively. Analysis of the metabolite concentrations from allantoic fluid by Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) showed clear separation between the embryos exposed to GW7647, rosiglitazone, and vehicle control, respectively. In blood plasma only GW7647 caused a significant effect on the metabolic profile. PFOA induced embryo mortality and increased relative liver weight at the highest dose. Sublethal doses of PFOA did not significantly affect the metabolic profile in either matrix, although single metabolites appeared to be altered. Neonatal mortality by PFOA in the mouse has been suggested to be mediated via activation of PPARα. However, we found no similarity in the metabolite profile of chicken embryos exposed to PFOA with those of embryos exposed to PPAR agonists. This indicates that PFOA does not activate PPAR pathways in our model at concentrations in eggs and embryos well above those found in wild birds. The present study suggests that allantoic fluid and plasma from chicken embryos are useful and complementary matrices for exploring effects on the metabolic profile resulting from chemical exposure during embryonic development. PMID:26624992

  10. Contrasting effects of phorbol ester and agonist-mediated activation of protein kinase C on phosphoinositide and Ca2+ signalling in a human neuroblastoma.

    PubMed Central

    Willars, G B; Challiss, R A; Stuart, J A; Nahorski, S R

    1996-01-01

    The effects of protein kinase C (PKC) activation on muscarinic receptor-mediated phosphoinositide and Ca2+ signalling were examined in the human neuroblastoma, SH-SY5Y. Carbachol evoked rapid transient elevations of Ins(1,4,5)P3 and intracellular [Ca2+] followed by lower sustained elevations. Phorbol 12,13-dibutyrate (PDBu) preferentially attenuated transient phases. Removal of the transplasmalemmal Ca2+ gradient coupled with depletion of intracellular Ca2+ stores with thapsigargin also reduced carbachol-mediated Ins(1,4,5)P3 accumulation. Under these conditions, PDBu virtually abolished Ins(1,4,5)P3 responses to carbachol thereby implicating both Ca(2+)- and PKC-sensitive components. PDBu also reduced agonist-mediated accumulation of inositol phosphates and depletion of lipids, thereby eliminating an effect of PKC on Ins(1,4,5)P3 metabolism or phosphoinositide synthesis. In electroporated cells, PDBu inhibited Ins(1,4,5)P3 accumulation mediated by carbachol or guanosine 5'-[gamma-thio]-triphosphate, the latter indicating that some PDBu-sensitive elements were downstream of the receptor. The PKC inhibitor, Ro-318220, protected against PDBu but did not enhance responses to maximal concentrations of carbachol, indicating no feedback inhibition by agonist-activated PKC. Muscarinic antagonist activity of Ro-318220 complicated such assessment at low agonist concentrations. Carbachol or PDBu induced cytosol to membrane translocation of PKC alpha. This was faster and possibly greater with PDBu, which may explain the lack of feedback by agonist-activated PKC. These results indicate that, in SH-SY5Y cells, PDBu activation of PKC preferentially inhibits rapid muscarinic receptor-mediated phosphoinositide and Ca2+ responses via suppression of PtdIns(4,5)P2 hydrolysis. This is at least partially through inhibition of Gq-protein/phosphoinositidase C coupling. However, at least at high agonist concentrations, a major agonist-mediated PKC feedback is not present in these cells. PMID:8670170

  11. The inverse agonist propranolol confers no corticosteroid-sparing activity in mild-to-moderate persistent asthma.

    PubMed

    Anderson, William J; Short, Philip M; Williamson, Peter A; Manoharan, Arvind; Lipworth, Brian J

    2014-12-01

    The murine asthma model shows that switching off airway β2 receptors with an inverse agonist may confer anti-inflammatory effects as well as corticosteroid-sparing activity. We have assessed for any corticosteroid-sparing effects of propranolol, an inverse agonist, added to low-dose inhaled corticosteroid (ICS) compared with higher dose ICS. A randomized double-blind placebo-controlled cross-over trial in mild-to-moderate persistent asthmatic patients was performed. After a run-in (2 weeks) on hydrofluoroalkane-beclometasone dipropionate (HFA-BDP) at 100 μg/day (HFA-BDP100), patients received randomized treatments (4 weeks) with propranolol at 80 mg/day plus HFA-BDP at 100 μg/day compared with placebo plus HFA-BDP at 400 μg/day (HFA-BDP400). Propranolol was up-titrated to 80 mg/day over the initial 2 weeks. Tiotropium was co-administered until 5 days before each histamine challenge (the primary outcome). Sixteen patients completed the study [mean age, 38 years; forced expiratory volume in 1 s (FEV1), 86.4%; histamine provocative concentration causing a 20% fall in FEV1 (PC20), 1.39 mg/ml; ICS dose, 406 μg/day]. Histamine PC20 was unchanged by adding propranolol to HFA-BDP100 compared with baseline (HFA-BDP100) {0.17 doubling dilution (dd) difference [95% confidence interval (CI): -0.58 to 0.92]}, but there was a significant improvement with HFA-BDP400 compared with both baseline [1.05 dd (95% CI: 0.43-1.66); P=0.02], and propranolol+HFA-BDP100 [0.88 dd (95% CI: 0.45-1.30); P=0.006]. Significant improvements were also observed with HFA-BDP400 for exhaled nitric oxide, blood eosinophils, serum eosinophilic cationic protein and asthma quality-of-life questionnaire symptoms compared with propranolol+HFA-BDP100. Salbutamol recovery post-challenge was partially blunted by propranolol (median prolongation 5 min; P=0.002). Domiciliary evening FEV1 also fell with propranolol+HFA-BDP100 [mean reduction from baseline 0.22 litres (95% CI: 0.10-0.34); P=0.012], whereas Asthma Control Questionnaire remained unchanged. In conclusion, the inverse agonist propranolol produced no improvements when given with low-dose ICS, whereas further significant improvements in airway hyper-responsiveness and inflammation were demonstrated with higher dose ICS. Thus, propranolol does not confer corticosteroid-sparing activity in persistent asthma. PMID:24938324

  12. Active-state model of a dopamine D2 receptor-Gαi complex stabilized by aripiprazole-type partial agonists.

    PubMed

    Kling, Ralf C; Tschammer, Nuska; Lanig, Harald; Clark, Timothy; Gmeiner, Peter

    2014-01-01

    Partial agonists exhibit a submaximal capacity to enhance the coupling of one receptor to an intracellular binding partner. Although a multitude of studies have reported different ligand-specific conformations for a given receptor, little is known about the mechanism by which different receptor conformations are connected to the capacity to activate the coupling to G-proteins. We have now performed molecular-dynamics simulations employing our recently described active-state homology model of the dopamine D2 receptor-Gαi protein-complex coupled to the partial agonists aripiprazole and FAUC350, in order to understand the structural determinants of partial agonism better. We have compared our findings with our model of the D2R-Gαi-complex in the presence of the full agonist dopamine. The two partial agonists are capable of inducing different conformations of important structural motifs, including the extracellular loop regions, the binding pocket and, in particular, intracellular G-protein-binding domains. As G-protein-coupling to certain intracellular epitopes of the receptor is considered the key step of allosterically triggered nucleotide-exchange, it is tempting to assume that impaired coupling between the receptor and the G-protein caused by distinct ligand-specific conformations is a major determinant of partial agonist efficacy. PMID:24932547

  13. Active-State Model of a Dopamine D2 Receptor - Gαi Complex Stabilized by Aripiprazole-Type Partial Agonists

    PubMed Central

    Kling, Ralf C.; Tschammer, Nuska; Lanig, Harald; Clark, Timothy; Gmeiner, Peter

    2014-01-01

    Partial agonists exhibit a submaximal capacity to enhance the coupling of one receptor to an intracellular binding partner. Although a multitude of studies have reported different ligand-specific conformations for a given receptor, little is known about the mechanism by which different receptor conformations are connected to the capacity to activate the coupling to G-proteins. We have now performed molecular-dynamics simulations employing our recently described active-state homology model of the dopamine D2 receptor-Gαi protein-complex coupled to the partial agonists aripiprazole and FAUC350, in order to understand the structural determinants of partial agonism better. We have compared our findings with our model of the D2R-Gαi-complex in the presence of the full agonist dopamine. The two partial agonists are capable of inducing different conformations of important structural motifs, including the extracellular loop regions, the binding pocket and, in particular, intracellular G-protein-binding domains. As G-protein-coupling to certain intracellular epitopes of the receptor is considered the key step of allosterically triggered nucleotide-exchange, it is tempting to assume that impaired coupling between the receptor and the G-protein caused by distinct ligand-specific conformations is a major determinant of partial agonist efficacy. PMID:24932547

  14. Peroxisome proliferator-activated receptor delta agonists inhibit T helper type 1 (Th1) and Th17 responses in experimental allergic encephalomyelitis.

    PubMed

    Kanakasabai, Saravanan; Chearwae, Wanida; Walline, Crystal C; Iams, Wade; Adams, Suzanne M; Bright, John J

    2010-08-01

    Multiple sclerosis (MS) is a neurological disorder that affects more than a million people world-wide. The aetiology of MS is not known and there is no medical treatment available that can cure MS. Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune disease model of MS. The pathogenesis of EAE/MS is a complex process involving activation of immune cells, secretion of inflammatory cytokines and destruction of myelin sheath in the central nervous system (CNS). Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptor transcription factors that regulate cell growth, differentiation and homeostasis. PPAR agonists have been used in the treatment of obesity, diabetes, cancer and inflammation. We and others have shown that PPARgamma, alpha and delta agonists inhibit CNS inflammation and demyelination in the EAE model of MS. In this study we show that the PPARdelta agonists GW501516 and L165041 ameliorate MOGp35-55-induced EAE in C57BL/6 mice by blocking interferon (IFN)-gamma and interleukin (IL)-17 production by T helper type 1 (Th1) and Th17 cells. The inhibition of EAE by PPARdelta agonists was also associated with a decrease in IL-12 and IL-23 and an increase in IL-4 and IL-10 expression in the CNS and lymphoid organs. These findings indicate that PPARdelta agonists modulate Th1 and Th17 responses in EAE and suggest their use in the treatment of MS and other autoimmune diseases. PMID:20406305

  15. Discovery of Tetrahydropyrazolopyridine as Sphingosine 1-Phosphate Receptor 3 (S1P3)-Sparing S1P1 Agonists Active at Low Oral Doses.

    PubMed

    Demont, Emmanuel H; Bailey, James M; Bit, Rino A; Brown, Jack A; Campbell, Colin A; Deeks, Nigel; Dowell, Simon J; Eldred, Colin; Gaskin, Pam; Gray, James R J; Haynes, Andrea; Hirst, David J; Holmes, Duncan S; Kumar, Umesh; Morse, Mary A; Osborne, Greg J; Renaux, Jessica F; Seal, Gail A L; Smethurst, Chris A; Taylor, Simon; Watson, Robert; Willis, Robert; Witherington, Jason

    2016-02-11

    FTY720 is the first oral small molecule approved for the treatment of people suffering from relapsing-remitting multiple sclerosis. It is a potent agonist of the S1P1 receptor, but its lack of selectivity against the S1P3 receptor has been linked to most of the cardiovascular side effects observed in the clinic. These findings have triggered intensive efforts toward the identification of a second generation of S1P3-sparing S1P1 agonists. We have recently disclosed a series of orally active tetrahydroisoquinoline (THIQ) compounds matching these criteria. In this paper we describe how we defined and implemented a strategy aiming at the discovery of selective structurally distinct follow-up agonists. This effort culminated with the identification of a series of orally active tetrahydropyrazolopyridines. PMID:26751273

  16. Dual Peroxisome ProliferatorActivated Receptor ?/? Agonist GFT505 Improves Hepatic and Peripheral Insulin Sensitivity in Abdominally Obese Subjects

    PubMed Central

    Cariou, Bertrand; Hanf, Rmy; Lambert-Porcheron, Stphanie; Zar, Yassine; Sauvinet, Valrie; Nol, Benoit; Flet, Laurent; Vidal, Hubert; Staels, Bart; Laville, Martine

    2013-01-01

    OBJECTIVE The development of new insulin sensitizers is an unmet need for the treatment of type 2 diabetes. We investigated the effect of GFT505, a dual peroxisome proliferatoractivated receptor (PPAR)-?/? agonist, on peripheral and hepatic insulin sensitivity. RESEARCH DESIGN AND METHODS Twenty-two abdominally obese insulin-resistant males (homeostasis model assessment of insulin resistance >3) were randomly assigned in a randomized crossover study to subsequent 8-week treatment periods with GFT505 (80 mg/day) or placebo, followed by a two-step hyperinsulinemic-euglycemic insulin clamp with a glucose tracer to calculate endogenous glucose production (EGP). The primary end point was the improvement in glucose infusion rate (GIR). Gene expression analysis was performed on skeletal muscle biopsy specimens. RESULTS GFT505 improved peripheral insulin sensitivity, with a 21% (P = 0.048) increase of the GIR at the second insulin infusion period. GFT505 also enhanced hepatic insulin sensitivity, with a 44% (P = 0.006) increase of insulin suppression of EGP at the first insulin infusion period. Insulin-suppressed plasma free fatty acid concentrations were significantly reduced on GFT505 treatment (0.21 0.07 vs. 0.27 0.11 mmol/L; P = 0.006). Neither PPAR? nor PPAR? target genes were induced in skeletal muscle, suggesting a liver-targeted action of GFT505. GFT505 significantly reduced fasting plasma triglycerides (?21%; P = 0.003) and LDL cholesterol (?13%; P = 0.0006), as well as liver enzyme concentrations (?-glutamyltranspeptidase: ?30.4%, P = 0.003; alanine aminotransferase: ?20.5%, P = 0.004). There was no safety concern or any indication of PPAR? activation with GFT505. CONCLUSIONS The dual PPAR?/? agonist GFT505 is a liver-targeted insulin-sensitizer that is a promising drug candidate for the treatment of type 2 diabetes and nonalcoholic fatty liver disease. PMID:23715754

  17. p38 mitogen-activated protein kinase activation in amygdala mediates κ opioid receptor agonist U50,488H-induced conditioned place aversion.

    PubMed

    Zan, G-Y; Wang, Q; Wang, Y-J; Chen, J-C; Wu, X; Yang, C-H; Chai, J-R; Li, M; Liu, Y; Hu, X-W; Shu, X-H; Liu, J-G

    2016-04-21

    κ opioid receptor agonists produce aversive effects in rodents, however the underlying mechanisms remain unclear. Activation of p38 mitogen-activated protein kinase (MAPK) has been discovered to play a critical role in the modulation of affective behaviors. The present study was undertaken to detect the possible involvement of p38 MAPK in the aversive effects induced by κ opioid receptor activation. We found that the κ opioid receptor agonist trans-(±)-3,4-Dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzenacetamide methanesulfonate salt (U50,488H) produced significant place aversion in mice as measured by the conditioned place preference procedure, accompanied with significant p38 MAPK activation in the amygdala, but not in the nucleus accumbens and hippocampus. Stereotaxic microinjection of the p38 MAPK inhibitor 4-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-5-(4-pyridy-l)-1H-imidazole (SB203580) into amygdala significantly inhibited p38 MAPK activation and completely blocked the conditioned place aversion in mice. Thus, these results suggested that activation of p38 MAPK in the amygdala was required to mediate κ opioid receptor-induced aversive behavior. PMID:26826330

  18. Vanidilol: a vanilloid-type vasorelaxant and ocular hypotensive beta-adrenoceptor blocker with partial beta-2-agonist activity.

    PubMed

    Sheu, M M; Wu, B N; Ho, W C; Hong, S J; Chen, S J; Lin, Y T; Chen, I J

    1997-04-01

    Vanidilol, [4'-(2-hydroxy-3-(tert-butylamino)propoxy)-3'-methoxyphenyl] -benzaldehyde, newly synthesized from vanillin, is a vanilloid-type beta-adrenoceptor blocker. The beta-adrenoceptor-blocking properties of vanidilol were studied both in vivo and in vitro. Intravenous injection of vanidilol (1.0, 3.0, 5.0 mg/kg) in anesthetized Wistar rats produced a decrease in blood pressure and a dose-dependent bradycardia response. Vanidilol inhibited the tachycardia effects induced by (-)isoproterenol, but had no blocking effect on the arterial pressor responses induced by phenylephrine. In isolated guinea-pig tissues, vanidilol attenuated the (-)isoproterenol-induced positive chronotropic and inotropic effects of the atria and trachea relaxation responses in a concentration-dependent manner. The parallel shift to the right of the concentration-response curve of (-)isoproterenol suggested that the agent was a beta-adrenoceptor competitive antagonist. The apparent pA2 values for vanidilol on the right atria, left atria and trachea were 7.67 +/- 0.03, 7.89 +/- 1.02 and 7.66 +/- 0.15, respectively, denoting that vanidilol was a nonselective beta-blocker. The intrinsic sympathomimetic activity of vanidilol and propranolol was determined on isolated atria and trachea from reserpinized guinea pigs. Propranolol caused significantly negative inotropic and chronotropic effects at 10(-6) mol/l or above, whereas vanidilol possessed less cardiodepressant activities than propranolol. In reserpinized tracheal strips, vanidilol produced dose-dependent relaxant responses, but propranolol was ineffective. Preincubating the preparations with ICI 118,551 (0.1-10 nmol/l), a beta 2-adrenoceptor antagonist, significantly shifted the concentration-relaxation curves of vanidilol to a region of higher concentrations. In isolated guinea-pig thoracic aorta, vanidilol (0.1-10 mumol/l) inhibited the phenylephrine (10(-5) mol/l)-induced tonic contraction in vascular smooth muscle which was related to the block of calcium influx. In 20% saline-perfused rabbits, vanidilol showed a marked delay in intraocular pressure recovery, demonstrating an ocular hypotensive action. Binding characteristics of vanidilol and propranolol were evaluated in [3H]dihydroalprenolol binding to porcine ventricular membranes. Vanidilol was less potent than propranolol in competing for the beta-adrenoceptor-binding sites. On the other hand, vanidilol had a high hydrophilicity in comparison with propranolol. In conclusion, vanidilol exhibited nonselective beta-adrenoceptor blocking, vasorelaxant and ocular hypotensive activities, but was devoid of alpha-adrenoceptor blocking and beta 1-agonist activity. Partial beta 2-adrenoceptor agonist activity and inhibitory activity on calcium influx may share in the vasorelaxant activity. PMID:9211567

  19. Agonist activation of cytosolic Ca2+ in subfornical organ cells projecting to the supraoptic nucleus

    NASA Technical Reports Server (NTRS)

    Johnson, R. F.; Beltz, T. G.; Sharma, R. V.; Xu, Z.; Bhatty, R. A.; Johnson, A. K.

    2001-01-01

    The subfornical organ (SFO) is sensitive to both ANG II and ACh, and local application of these agents produces dipsogenic responses and vasopressin release. The present study examined the effects of cholinergic drugs, ANG II, and increased extracellular osmolarity on dissociated, cultured cells of the SFO that were retrogradely labeled from the supraoptic nucleus. The effects were measured as changes in cytosolic calcium in fura 2-loaded cells by using a calcium imaging system. Both ACh and carbachol increased intracellular ionic calcium concentration ([Ca2+]i). However, in contrast to the effects of muscarinic receptor agonists on SFO neurons, manipulation of the extracellular osmolality produced no effects, and application of ANG II produced only moderate effects on [Ca2+]i in a few retrogradely labeled cells. The cholinergic effects on [Ca2+]i could be blocked with the muscarinic receptor antagonist atropine and with the more selective muscarinic receptor antagonists pirenzepine and 4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP). In addition, the calcium in the extracellular fluid was required for the cholinergic-induced increase in [Ca2+]i. These findings indicate that ACh acts to induce a functional cellular response in SFO neurons through action on a muscarinic receptor, probably of the M1 subtype and that the increase of [Ca2+]i, at least initially, requires the entry of extracellular Ca2+. Also, consistent with a functional role of M1 receptors in the SFO are the results of immunohistochemical preparations demonstrating M1 muscarinic receptor-like protein present within this forebrain circumventricular organ.

  20. The adenosine A2A receptor antagonist, istradefylline enhances the anti-parkinsonian activity of low doses of dopamine agonists in MPTP-treated common marmosets.

    PubMed

    Uchida, Shin-ichi; Soshiroda, Kazuhiro; Okita, Eri; Kawai-Uchida, Mika; Mori, Akihisa; Jenner, Peter; Kanda, Tomoyuki

    2015-01-15

    The adenosine A2A receptor antagonist, istradefylline, enhances anti-parkinsonian activity in patients with advanced Parkinson׳s disease (PD) already treated with combinations of L-DOPA and dopamine agonist drugs but who are still exhibiting prolonged 'OFF' periods. In contrast, the effects of istradefylline on motor function when administered in combination with low dose dopamine agonist therapy in early PD are unknown. We now investigate whether istradefylline administered with a threshold dose of either the non-ergot dopamine agonist, ropinirole or the ergot dopamine agonist, pergolide enhances anti-parkinsonian activity in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated common marmoset. Both ropinirole (0.01-0.1mg/kg p.o.) and pergolide (0.003-0.1mg/kg p.o.) administered alone produced dose dependent increases in locomotor activity, a reduction in motor disability. Threshold doses of ropinirole (0.025-0.075mg/kg p.o.) and pergolide (0.01-0.075mg/kg p.o.) were then selected that in individual animals caused a small but non-significant anti-parkinsonian effect. Administration of istradefylline (10mg/kg p.o.) alone resulted in a decrease in motor disability and increase in 'ON' time but dyskinesia was not observed. Combined administration of pergolide or ropinirole with istradefylline resulted in an increase in the reversal of motor disability and increase in 'ON' time compared to that produced by either treatment alone but dyskinesia was still not observed. These results show that istradefylline is effective in improving motor function when combined with low dose dopamine agonist treatment. In early PD, this may avoid dose escalation or allow a reduction in dopamine agonist dosage without a loss of efficacy and prevent dopaminergic side-effects from becoming treatment limiting. PMID:25499739

  1. Effect of beta-ADrenergic Agonist on Cyclic AMP Synthesis in Chicken Skeletal Muscle Cells in Culture

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Because it seems logical that these agonists exert their action on muscle through stimulation of cAMP synthesis, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax levels were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. In addition, the EC50 values for isoproterenol, cimaterol, clenbuterol, epinephrine, and albuterol were 360 nM, 630 nM, 900 nM, 2,470 nM, and 3,650 nM, respectively. Finally, dose response curves show that the concentrations of cimaterol and clenbuterol in culture media at concentrations known to cause significant muscle hypertrophy in animals had no detectable effect on stimulation of CAMP accumulation in chicken skeletal muscle cells.

  2. Design, synthesis and Structure-activity relationship studies of new thiazole-based free fatty acid receptor 1 agonists for the treatment of type 2 diabetes.

    PubMed

    Li, Zheng; Qiu, Qianqian; Xu, Xue; Wang, Xuekun; Jiao, Lei; Su, Xin; Pan, Miaobo; Huang, Wenlong; Qian, Hai

    2016-05-01

    The free fatty acid receptor 1 (FFA1/GPR40) has attracted interest as a novel target for the treatment of type 2 diabetes. Several series of FFA1 agonists including TAK-875, the most advanced compound terminated in phase III studies due to concerns about liver toxicity, have been hampered by relatively high molecular weight and lipophilicity. Aiming to develop potent FFA1 agonists with low risk of liver toxicity by decreasing the lipophilicity, the middle phenyl of TAK-875 was replaced by 11 polar five-membered heteroaromatics. Subsequently, systematic exploration of SAR and application of molecular modeling, leads to the identification of compound 44, which was an excellent FFA1 agonist with robustly hypoglycemic effect both in normal and type 2 diabetic mice, low risks of hypoglycemia and liver toxicity even at the twice molar dose of TAK-875. Meanwhile, two important findings were noted. First, the methyl group in our thiazole series occupied a small hydrophobic subpocket which had no interactions with TAK-875. Furthermore, the agonistic activity revealed a good correlation with the dihedral angle between thiazole core and the terminal benzene ring. These results promote the understanding of ligand-binding pocket and might help to design more promising FFA1 agonists. PMID:26945112

  3. Peroxisome proliferator-activated receptor-{gamma} agonists inhibit the replication of respiratory syncytial virus (RSV) in human lung epithelial cells

    SciTech Connect

    Arnold, Ralf . E-mail: ralf.arnold@medizin.uni-magdeburg.de; Koenig, Wolfgang

    2006-07-05

    We have previously shown that peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}) agonists inhibited the inflammatory response of RSV-infected human lung epithelial cells. In this study, we supply evidence that specific PPAR{gamma} agonists (15d-PGJ{sub 2}, ciglitazone, troglitazone, Fmoc-Leu) efficiently blocked the RSV-induced cytotoxicity and development of syncytia in tissue culture (A549, HEp-2). All PPAR{gamma} agonists under study markedly inhibited the cell surface expression of the viral G and F protein on RSV-infected A549 cells. This was paralleled by a reduced cellular amount of N protein-encoding mRNA determined by real-time RT-PCR. Concomitantly, a reduced release of infectious progeny virus into the cell supernatants of human lung epithelial cells (A549, normal human bronchial epithelial cells (NHBE)) was observed. Similar results were obtained regardless whether PPAR{gamma} agonists were added prior to RSV infection or thereafter, suggesting that the agonists inhibited viral gene expression and not the primary adhesion or fusion process.

  4. Autaptic pacemaker mediated propagation of weak rhythmic activity across small-world neuronal networks

    NASA Astrophysics Data System (ADS)

    Yilmaz, Ergin; Baysal, Veli; Ozer, Mahmut; Perc, Matjaž

    2016-02-01

    We study the effects of an autapse, which is mathematically described as a self-feedback loop, on the propagation of weak, localized pacemaker activity across a Newman-Watts small-world network consisting of stochastic Hodgkin-Huxley neurons. We consider that only the pacemaker neuron, which is stimulated by a subthreshold periodic signal, has an electrical autapse that is characterized by a coupling strength and a delay time. We focus on the impact of the coupling strength, the network structure, the properties of the weak periodic stimulus, and the properties of the autapse on the transmission of localized pacemaker activity. Obtained results indicate the existence of optimal channel noise intensity for the propagation of the localized rhythm. Under optimal conditions, the autapse can significantly improve the propagation of pacemaker activity, but only for a specific range of the autaptic coupling strength. Moreover, the autaptic delay time has to be equal to the intrinsic oscillation period of the Hodgkin-Huxley neuron or its integer multiples. We analyze the inter-spike interval histogram and show that the autapse enhances or suppresses the propagation of the localized rhythm by increasing or decreasing the phase locking between the spiking of the pacemaker neuron and the weak periodic signal. In particular, when the autaptic delay time is equal to the intrinsic period of oscillations an optimal phase locking takes place, resulting in a dominant time scale of the spiking activity. We also investigate the effects of the network structure and the coupling strength on the propagation of pacemaker activity. We find that there exist an optimal coupling strength and an optimal network structure that together warrant an optimal propagation of the localized rhythm.

  5. Differential effects of peroxisome proliferator-activated receptor agonists on doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells.

    PubMed

    Yousefi, B; Samadi, N; Baradaran, B; Rameshknia, V; Shafiei-Irannejad, V; Majidinia, M; Targhaze, N; Zarghami, N

    2015-01-01

    P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in tumor cells is still a main obstacle for the chemotherapeutic treatment of cancers. Therefore, identification of safe and effective MDR reversing compounds with minimal adverse side effects is an important approach in the cancer treatment. Studies show that peroxisome proliferator-activated receptor (PPARs) ligands can inhibit cell growth in many cancers. Here, we investigated the effect of different PPAR agonists include fenofibrate, troglitazone and aleglitazar on doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. The effects of doxorubicin (DOX) following treatment with PPAR agonists on cell viability were evaluated using MTT assay and the reversal fold (RF) values. Rhodamine123 (Rh123) assays were used to determine P-gp functioning. P-gp mRNA/protein expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis after incubation with troglitazone and aleglitazar. Our results showed that troglitazone and aleglitazar significantly enhanced the cytotoxicity of DOX and decreased the RF values in K562/DOX cells, however, no such results were found for fenofibrate. Troglitazone and aleglitazar significantly down regulated P-gp expression in K562/DOX cells; in addition, the present study revealed that aleglitazar elevated intracellular accumulation of Rh123in K562/DOX cells as short-term effects, which also contribute to the reversal of MDR. These findings show that troglitazone and especially aleglitazar exhibited potent effects in the reversal of P-gp-mediated MDR, suggesting that these compounds may be effective for combination therapy strategies and circumventing MDR in K562/DOX cells to other conventional chemotherapeutic drugs. PMID:26718439

  6. Glucagon-like peptide-1 receptor agonist activation ameliorates venous thrombosis-induced arteriovenous fistula failure in chronic kidney disease.

    PubMed

    Chien, Chiang-Ting; Fan, Shih-Chen; Lin, Shao-Chieh; Kuo, Chang-Chih; Yang, Chih-Hui; Yu, Tzu-Ying; Lee, Shih-Pin; Cheng, Dai-Yu; Li, Ping-Chia

    2014-11-01

    High shear stress that develops in the arteriovenous fistula of chronic kidney diseases (CKD) may increase H2O2 and thromboxane A2 (TXA2) release, thereby exacerbating endothelial dysfunction, thrombosis, and neointimal hyperplasia. We investigated whether glucagon-like peptide-1 receptor agonist/exendin-4, a potentially cardiovascular protective agent, could improve TXA2-induced arteriovenous fistula injury in CKD. TXA2 administration to H2O2-exposed human umbilical vein endothelial cells increased apoptosis, senescence, and detachment; these phenotypes were associated with the downregulation of phosphorylated endothelial nitric oxide synthase/heme oxygenase-1 (eNOS/HO-1) signalling. Exendin-4 reduced H2O2/TXA2-induced endothelial injury via inhibition of apoptosis-related mechanisms and restoration of phosphorylated eNOS/HO-1 signalling. Male Wistar rats subjected to right common carotid artery-external jugular vein anastomosis were treated with exendin-4 via cervical implant osmotic pumps for 16-42 days. High shear stress induced by the arteriovenous fistula significantly increased venous haemodynamics, blood and tissue H2O2 and TXB2 levels, macrophage/monocyte infiltration, fibrosis, proliferation, and adhesion molecule-1 expression. Apoptosis was also increased due to NADPH oxidase gp91 activation and mitochondrial Bax translocation in the proximal end of the jugular vein of CKD rats. Exendin-4-treatment of rats with CKD led to the restoration of normal endothelial morphology and correction of arteriovenous fistula function. Exendin-4 treatment or thromboxane synthase gene deletion in CKD mice markedly reduced ADP-stimulated platelet adhesion to venous endothelium, and prevented venous occlusion in FeCl3-injured vessels by upregulation of HO-1. Together, these data reveal that the use of glucagon-like peptide-1 receptor agonists is an effective strategy for treatment of CKD-induced arteriovenous fistula failure. PMID:25030617

  7. Differential pathway coupling efficiency of the activated insulin receptor drives signaling selectivity by XMetA, an allosteric partial agonist antibody

    Technology Transfer Automated Retrieval System (TEKTRAN)

    XMetA, an anti-insulin receptor (IR) monoclonal antibody, is an allosteric partial agonist of the IR. We have previously reported that XMetA activates the “metabolic-biased” Akt kinase signaling pathway while having little or no effect on the “mitogenic” MAPK signaling pathwayof ERK 1/2. To inves...

  8. CORRELATION OF THE ANTICHOLINESTERASE ACTIVITY OF A SERIES OF ORGANOPHOSPHATES WITH THEIR ABILITY TO COMPETE WITH AGONIST BINDING TO MUSCARINIC RECEPTORS

    EPA Science Inventory

    Some compounds that inhibit acetylcholinesterase (ACHE) activity compete directly with quinuclidinyl benzilate (QNB) binding, a muscarinic antagonist which binds to all subtypes equally, and with cis-methyldioxolane (CD), an agonist that binds with high affinity to the M2 subtype...

  9. A GPBAR1 (TGR5) small molecule agonist shows specific inhibitory effects on myeloid cell activation in vitro and reduces experimental autoimmune encephalitis (EAE) in vivo.

    PubMed

    Lewis, Nuruddeen D; Patnaude, Lori A; Pelletier, Josephine; Souza, Donald J; Lukas, Susan M; King, F James; Hill, Jonathan D; Stefanopoulos, Dimitria E; Ryan, Kelli; Desai, Sudha; Skow, Donna; Kauschke, Stefan G; Broermann, Andre; Kuzmich, Daniel; Harcken, Christian; Hickey, Eugene R; Modis, Louise K

    2014-01-01

    GPBAR1 is a G protein-coupled receptor that is activated by certain bile acids and plays an important role in the regulation of bile acid synthesis, lipid metabolism, and energy homeostasis. Recent evidence suggests that GPBAR1 may also have important effects in reducing the inflammatory response through its expression on monocytes and macrophages. To further understand the role of GPBAR1 in inflammation, we generated a novel, selective, proprietary GPBAR1 agonist and tested its effectiveness at reducing monocyte and macrophage activation in vitro and in vivo. We have used this agonist, together with previously described agonists to study agonism of GPBAR1, and shown that they can all induce cAMP and reduce TLR activation-induced cytokine production in human monocytes and monocyte-derived macrophages in vitro. Additionally, through the usage of RNA sequencing (RNA-Seq), we identified a select set of genes that are regulated by GPBAR1 agonism during LPS activation. To further define the in vivo role of GPBAR1 in inflammation, we assessed GPBAR1 expression and found high levels on circulating mouse monocytes. Agonism of GPBAR1 reduced LPS-induced cytokine production in mouse monocytes ex vivo and serum cytokine levels in vivo. Agonism of GPBAR1 also had profound effects in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis, where monocytes play an important role. Mice treated with the GPBAR1 agonist exhibited a significant reduction in the EAE clinical score which correlated with reduced monocyte and microglial activation and reduced trafficking of monocytes and T cells into the CNS. These data confirm the importance of GPBAR1 in controlling monocyte and macrophage activation in vivo and support the rationale for selective agonists of GPBAR1 in the treatment of inflammatory diseases. PMID:24967665

  10. Identification of 6-octadecynoic acid from a methanol extract of Marrubium vulgare L. as a peroxisome proliferator-activated receptor γ agonist

    SciTech Connect

    Ohtera, Anna; Miyamae, Yusaku; Nakai, Naomi; Kawachi, Atsushi; Kawada, Kiyokazu; Han, Junkyu; Isoda, Hiroko; Faculty of Life and Environment, University of Tsukuba, Ibaraki 305-8572 ; Neffati, Mohamed; Akita, Toru; Maejima, Kazuhiro; Masuda, Seiji; Kambe, Taiho; Mori, Naoki; Irie, Kazuhiro; Nagao, Masaya

    2013-10-18

    Highlights: •6-ODA, a rare fatty acid with a triple bond, was identified from Marrubium vulgare. •6-ODA was synthesized from petroselinic acid as a starting material. •6-ODA stimulated lipid accumulation in HSC-T6 and 3T3-L1 cells. •The first report of a fatty acid with a triple bond functioning as a PPARγ agonist. •This study sheds light on novel functions of a fatty acid with a triple bond. -- Abstract: 6-Octadecynoic acid (6-ODA), a fatty acid with a triple bond, was identified in the methanol extract of Marrubium vulgare L. as an agonist of peroxisome proliferator-activated receptor γ (PPARγ). Fibrogenesis caused by hepatic stellate cells is inhibited by PPARγ whose ligands are clinically used for the treatment of diabetes. Plant extracts of Marrubium vulgare L., were screened for activity to inhibit fibrosis in the hepatic stellate cell line HSC-T6 using Oil Red-O staining, which detects lipids that typically accumulate in quiescent hepatic stellate cells. A methanol extract with activity to stimulate accumulation of lipids was obtained. This extract was found to have PPARγ agonist activity using a luciferase reporter assay. After purification using several chromatographic methods, 6-ODA, a fatty acid with a triple bond, was identified as a candidate of PPARγ agonist. Synthesized 6-ODA and its derivative 9-octadecynoic acid (9-ODA), which both have a triple bond but in different positions, activated PPARγ in a luciferase reporter assay and increased lipid accumulation in 3T3-L1 adipocytes in a PPARγ-dependent manner. There is little information about the biological activity of fatty acids with a triple bond, and to our knowledge, this is the first report that 6-ODA and 9-ODA function as PPARγ agonists.

  11. Quantitative structure-activity relationships for weak acid respiratory uncouplers to Vibrio fisheri

    SciTech Connect

    Schultz, T.W.; Cronin, M.T.D.

    1997-02-01

    Acute toxicity values of 16 organic compounds thought to elicit their response via the weak acid respiratory uncoupling mechanism of toxic action were secured from the literature. Regression analysis of toxicities revealed that a measured 5-min V. fisheri potency value can be used as a surrogate for the 30-min value. Regression analysis of toxicity versus hydrophobicity, measured as the 1-octanol/water partition coefficient (log K{sub ow}), was used to formulate a quantitative structure-activity relationship (QSAR). The equation log pT{sub 30}{sup {minus}1} = 0.489(log K{sub ow}) + 0.126 was found to be a highly predictive model. This V. fisheri QSAR is statistically similar to QSARs generated from weak acid uncoupler potency data for Pimephales promelas survivability and Tetrahymena pyriformis population growth impairment. This work, therefore, suggests that the weak acid respiratory uncoupling mechanism of toxic action is present in V. fisheri, and as such is not restricted to mitochondria-containing organisms.

  12. Synthesis and Structure–Activity Relationships of N-Benzyl Phenethylamines as 5-HT2A/2C Agonists

    PubMed Central

    2014-01-01

    N-Benzyl substitution of 5-HT2A receptor agonists of the phenethylamine structural class of psychedelics (such as 4-bromo-2,5-dimethoxyphenethylamine, often referred to as 2C-B) confer a significant increase in binding affinity as well as functional activity of the receptor. We have prepared a series of 48 compounds with structural variations in both the phenethylamine and N-benzyl part of the molecule to determine the effects on receptor binding affinity and functional activity at 5-HT2A and 5-HT2C receptors. The compounds generally had high affinity for the 5-HT2A receptor with 8b having the highest affinity at 0.29 nM but with several other compounds also exhibiting subnanomolar binding affinities. The functional activity of the compounds was distributed over a wider range with 1b being the most potent at 0.074 nM. Most of the compounds exhibited low to moderate selectivity (1- to 40-fold) for the 5-HT2A receptor in the binding assays, although one compound 6b showed an impressive 100-fold selectivity for the 5-HT2A receptor. In the functional assay, selectivity was generally higher with 1b being more than 400-fold selective for the 5-HT2A receptor. PMID:24397362

  13. Peroxisome Proliferator-Activated Receptor (PPAR) γ and PPARα Agonists Modulate Mitochondrial Fusion-Fission Dynamics: Relevance to Reactive Oxygen Species (ROS)-Related Neurodegenerative Disorders?

    PubMed Central

    Zolezzi, Juan M.; Silva-Alvarez, Carmen; Ordenes, Daniela; Godoy, Juan A.; Carvajal, Francisco J.; Santos, Manuel J.; Inestrosa, Nibaldo C.

    2013-01-01

    Recent studies showed that the activation of the retinoid X receptor, which dimerizes with peroxisome proliferator-activated receptors (PPARs), leads to an enhanced clearance of Aβ from the brain of transgenic mice model of Alzheimer’s disease (AD), because an increased expression of apolipoprotein E and it main transporters. However, the effects observed must involve additional underlying mechanisms that have not been yet explored. Several studies conducted in our laboratory suggest that part of the effects observed for the PPARs agonist might involves mitochondrial function and, particularly, mitochondrial dynamics. In the present study we assessed the effects of oxidative stress challenge on mitochondrial morphology and mitochondrial dynamics-related proteins in hippocampal neurons. Using immunofluorescence, we evaluated the PPARγ co-activator 1α (PGC-1α), dynamin related protein 1 (DRP1), mitochondrial fission protein 1 (FIS1), and mitochondrial length, in order to determine if PPARs agonist pre-treatment is able to protect mitochondrial population from hippocampal neurons through modulation of the mitochondrial fusion-fission events. Our results suggest that both a PPARγ agonist (ciglitazone) and a PPARα agonist (WY 14.643) are able to protect neurons by modulating mitochondrial fusion and fission, leading to a better response of neurons to oxidative stress, suggesting that a PPAR based therapy could acts simultaneously in different cellular components. Additionally, our results suggest that PGC-1α and mitochondrial dynamics should be further studied in future therapy research oriented to ameliorate neurodegenerative disorders, such as AD. PMID:23675519

  14. Preparation and Characterizations of Dispersible Fluorinated Hydroxyapatite Nanoparticles with Weak Antibacterial Activity.

    PubMed

    Furuzono, Tsutomu; Azuma, Yoshinao; Niigawa, Yuichi; Kogai, Yasumichi; Sawa, Yoshiki

    2016-01-01

    To develop a nanoscaled coating material for medical devices possessing weak antibacterial activity, dispersible and crystalline fluorinated hydroxyapatite (F-HAp) nanoparticles were prepared using antisintering agent to avoid calcination-induced sintering. The product was identical to fluorapatite, as determined by X-ray diffraction and Fourier transform infrared spectroscopy. The primary particles generally showed rod-shaped morphology with a length of 367 ± 67 nm and a width of 223 ± 21 nm measured by scanning electron microscopy (SEM). The dispersed average particle size (313 ± 51 nm) in ethanol analyzed by dynamic light scattering was almost the same as that obtained from the SEM images. In the evaluation of solubility in acidic aqueous solution, F-HAp and original hydroxyapatite (HAp) nanoparticles started to dissolve at around pH 3.4 and 4.2, respectively. Thus, the stability of F-HAp in a living body increased compared with original HAp. The antibacterial activity of F-HAp nanoparticles was higher than that of fluoride in sodium fluoride alone or the original HAp nanoparticles. However, it was estimated that the effect of F-HAp was much lower compared with that of silver, one of the popular antibacterial materials. Thus, the dispersed F-HAp nanoparticles possessing weak antimicrobial activity can be useful without severe damage to the living tissue. PMID:26720738

  15. Prp4 Kinase Grants the License to Splice: Control of Weak Splice Sites during Spliceosome Activation

    PubMed Central

    Razanau, Aleh; Zock-Emmenthal, Susanne; Lützelberger, Martin; Plath, Susann; Schmidt, Henning; Guerra-Moreno, Angel; Cozzuto, Luca; Ayté, José; Käufer, Norbert F.

    2016-01-01

    The genome of the fission yeast Schizosaccharomyces pombe encodes 17 kinases that are essential for cell growth. These include the cell-cycle regulator Cdc2, as well as several kinases that coordinate cell growth, polarity, and morphogenesis during the cell cycle. In this study, we further characterized another of these essential kinases, Prp4, and showed that the splicing of many introns is dependent on Prp4 kinase activity. For detailed characterization, we chose the genes res1 and ppk8, each of which contains one intron of typical size and position. Splicing of the res1 intron was dependent on Prp4 kinase activity, whereas splicing of the ppk8 intron was not. Extensive mutational analyses of the 5’ splice site of both genes revealed that proper transient interaction with the 5’ end of snRNA U1 governs the dependence of splicing on Prp4 kinase activity. Proper transient interaction between the branch sequence and snRNA U2 was also important. Therefore, the Prp4 kinase is required for recognition and efficient splicing of introns displaying weak exon1/5’ splice sites and weak branch sequences. PMID:26730850

  16. The FomA Porin from Fusobacterium nucleatum Is a Toll-Like Receptor 2 Agonist with Immune Adjuvant Activity

    PubMed Central

    Toussi, Deana N.; Liu, Xiuping

    2012-01-01

    Many bacterial components selectively activate immune and nonhematopoietic target cells via Toll-like receptor (TLR) signaling; modulation of such host responses defines the immune adjuvant properties of these bacterial products. For example, the outer membrane protein porins from Neisseria, Salmonella, and Shigella are known TLR2 agonists with established systemic and mucosal immune adjuvanticity. Early work indicated that the FomA porin from Fusobacterium nucleatum has immune adjuvant activity in mice. Using a purified recombinant FomA, we have verified its immune stimulatory properties and have defined a role for TLR2 signaling in its in vitro and in vivo activity. FomA induces interleukin 8 (IL-8) secretion and NF-κB-dependent luciferase activity in HEK cells expressing TLR2, IL-6 secretion, and cell surface upregulation of CD86 and major histocompatibility complex (MHC) II in primary B cells from wild-type mice, but it fails to activate cells from TLR2 knockout mice. Accordingly, the immune adjuvant activity of FomA is also TLR2 dependent. In a mouse model of immunization with ovalbumin (OVA), FomA induces enhanced production of OVA-specific IgM and IgG, including IgG1 and IgG2b antibodies, as well as enhanced secretion of IL-10 and IL-6, consistent with a Th2-type adjuvant effect. We also observe a moderate production of anti-FomA antibodies, suggesting that FomA is also immunogenic, a quality that is also TLR2 dependent. Therefore, modulation of host immune responses by FomA may be effective for targeting general host immunity not only to pathogens (as a novel TLR2 adjuvant) but also to F. nucleatum itself (as an antigen), expanding its use as a self-adjuvanted antigen in an immunization strategy against polymicrobial infections, including those by F. nucleatum. PMID:22623652

  17. Peroxisome-proliferator-activated receptor-{gamma} agonists inhibit the release of proinflammatory cytokines from RSV-infected epithelial cells

    SciTech Connect

    Arnold, Ralf . E-mail: ralf.arnold@medizin.uni-magdeburg.de; Koenig, Wolfgang

    2006-03-15

    The epithelial cells of the airways are the target cells for respiratory syncytial virus (RSV) infection and the site of the majority of the inflammation associated with the disease. Recently, peroxisome-proliferator-activated receptor {gamma} (PPAR{gamma}), a member of the nuclear hormone receptor superfamily, has been shown to possess anti-inflammatory properties. Therefore, we investigated the role of PPAR{gamma} agonists (15d-PGJ{sub 2}, ciglitazone and troglitazone) on the synthesis of RSV-induced cytokine release from RSV-infected human lung epithelial cells (A549). We observed that all PPAR{gamma} ligands inhibited dose-dependently the release of TNF-{alpha}, GM-CSF, IL-1{alpha}, IL-6 and the chemokines CXCL8 (IL-8) and CCL5 (RANTES) from RSV-infected A549 cells. Concomitantly, the PPAR{gamma} ligands diminished the cellular amount of mRNA encoding for IL-6, CXCL8 and CCL5 and the RSV-induced binding activity of the transcription factors NF-{kappa}B (p65/p50) and AP-1 (c-fos), respectively. Our data presented herein suggest a potential application of PPAR{gamma} ligands in the anti-inflammatory treatment of RSV infection.

  18. A synergistic interaction of 17-β-estradiol with specific cannabinoid receptor type 2 antagonist/inverse agonist on proliferation activity in primary human osteoblasts

    PubMed Central

    HOJNIK, MARKO; DOBOVIŠEK, LUKA; KNEZ, ŽELJKO; FERK, POLONCA

    2015-01-01

    The bone remodeling process is influenced by various factors, including estrogens and transmitters of the endocannabinoid system. In osteoblasts, cannabinoid receptors 2 (CB-2) are expressed at a much higher level compared to CB-1 receptors. Previous studies have shown that estrogens could influence CB-2 receptor expression. In the present study, the possible interactions of a specific CB-2 agonist and a specific CB-2 antagonist/inverse agonist with 17-β-estradiol were investigated in primary human osteoblasts (HOB). HOB cells were cultured in phenol red-free osteoblast growth medium (37°C, 5% CO2). In their 5th passage, HOB were exposed to different concentrations of i) 17-β-estradiol (1, 10 and 100 nM); ii) a specific CB-2 agonist (R,S)-AM1241 (1 and 7.5 µM); and iii) a specific CB-2 antagonist/inverse agonist AM630 (10 µM) and to selected combinations of the substances. After 24 and 48 h of incubation, HOB proliferation activity was measured using a WST-8 assay. Alkaline phosphatase activity was also evaluated using spectrophotometry. Concomitant exposure of HOB to 17-β-estradiol (10 nM) and to specific CB-2 antagonist/inverse agonist (10 µM) showed similar HOB proliferation activity to HOB incubated with 17-β-estradiol only at a 100 nM concentration. By contrast, concomitant incubation of HOB with 17-β-estradiol (10 nM) and specific CB-2 agonist (7.5 µM) resulted in decreased HOB proliferation activity as compared to HOB incubated with 17-β-estradiol only (10 nM). Similar findings were observed after 24 and 48 h of incubation. In all the experiments, HOB successfully passed the alkaline phosphatase differentiation test. In conclusion, for the first time a synergistic interaction between 17-β-estradiol and specific CB-2 antagonist/inverse agonist was observed in HOB. Understanding the molecular pathways of this interaction would be of great importance in developing more efficient and safer drugs for treating or preventing bone diseases. PMID:26171165

  19. Treatment with PPARα Agonist Clofibrate Inhibits the Transcription and Activation of SREBPs and Reduces Triglyceride and Cholesterol Levels in Liver of Broiler Chickens

    PubMed Central

    Zhang, Lijun; Li, Chunyan; Wang, Fang; Zhou, Shenghua; Shangguan, Mingjun; Xue, Lina; Zhang, Bianying; Ding, Fuxiang; Hui, Dequan; Liang, Aihua; He, Dongchang

    2015-01-01

    PPARα agonist clofibrate reduces cholesterol and fatty acid concentrations in rodent liver by an inhibition of SREBP-dependent gene expression. In present study we investigated the regulation mechanisms of the triglyceride- and cholesterol-lowering effect of the PPARα agonist clofibrate in broiler chickens. We observed that PPARα agonist clofibrate decreases the mRNA and protein levels of LXRα and the mRNA and both precursor and nuclear protein levels of SREBP1 and SREBP2 as well as the mRNA levels of the SREBP1 (FASN and GPAM) and SREBP2 (HMGCR and LDLR) target genes in the liver of treated broiler chickens compared to control group, whereas the mRNA level of INSIG2, which inhibits SREBP activation, was increased in the liver of treated broiler chickens compared to control group. Taken together, the effects of PPARα agonist clofibrate on lipid metabolism in liver of broiler chickens involve inhibiting transcription and activation of SREBPs and SREBP-dependent lipogenic and cholesterologenic gene expression, thereby resulting in a reduction of the triglyceride and cholesterol levels in liver of broiler chickens. PMID:26693219

  20. Capsaicin-like anti-obese activities of evodiamine from fruits of Evodia rutaecarpa, a vanilloid receptor agonist.

    PubMed

    Kobayashi, Y; Nakano, Y; Kizaki, M; Hoshikuma, K; Yokoo, Y; Kamiya, T

    2001-10-01

    Evodiamine, a major alkaloidal principle of Evodia fruits (Evodia rutaecarpa, Rutaceae), showed vanilloid receptor agonistic activities comparable to capsaicin. The Chinese literature refers to Evodia fruits as a "hot nature" herb. In spite of the similarities in the actions of evodiamine and capsaicin in vitro, evodiamine has no perceptible taste, including a peppery hot taste. Therefore, the effectiveness of evodiamine and the extract of Evodia fruits in preventing obesity on male C3H mice, or male SD rats were examined. When evodiamine was supplemented at 0.03% of the diet and fed to mice for 12 days, the perirenal fat weight became significantly lower than in the control group. The epididymal fat mass was also decreased in the evodiamine diet group. When evodiamine was supplemented at 0.02% in the form of ethanol extract of Evodia fruits to the high-fat diet and fed to rats for 21 days, the body weight, the perirenal fat weight, epididymal fat weight, the levels of serum free fatty acid, total lipids in the liver, triglyceride in the liver, and cholesterol level in the liver were significantly reduced as compared with the control diet group. Furthermore, both lipolytic activity in the perirenal fat tissue and specific GDP binding in brown adipose tissue mitochondria, as the biological index of enhanced heat production, were significantly increased in the evodiamine fed rats. Fasting mice subcutaneously administered 1-3 mg/kg evodiamine showed decreased core body temperature by 1-2 degrees C. This hypothermic effect was prevented by the pretreatment of intraperitoneally administered 10 mg/kg capsazepine, a vanilloid receptor antagonist. On the other hand, food-sated mice subcutaneously administered 1-3 mg/kg evodiamine showed unchanged core body temperature and increased tail skin temperature by more than 5 degrees C, suggesting the increased energy expenditure by enhanced heat dissipation. In conclusion, we have demonstrated that a novel non-pungent vanilloid receptor agonist, evodiamine, mimics the characteristic anti-obese effects induced by capsaicin. Evodiamine would induce heat loss and heat production at the same time and dissipate food energy, preventing the accumulation of perivisceral fat and the body weight increase. PMID:11582540

  1. Activation of small conductance Ca(2+)-dependent K+ channels by purinergic agonists in smooth muscle cells of the mouse ileum.

    PubMed

    Vogalis, F; Goyal, R K

    1997-08-01

    1. Whole-cell and single-channel K+ currents were recorded at room temperature (22-24 degrees C), from smooth muscle cells enzymatically dispersed from the mouse ileum, using variations of the patch-clamp technique. 2. Net outward K+ currents recorded through amphotericin-B-perforated patches in response to step depolarizations positive to -50 mV from a holding potential of -80 mV were decreased by up to 70% by external apamin (0.5 microM). Apamin-sensitive whole-cell currents were also recorded from cells perfused internally with 150 nM Ca2+ but not from cells perfused internally with 85 nM Ca2+. 3. Three types of non-inactivating Ca(2+)-sensitive K+ channels were identified in cell-attached and excised patches under an asymmetrical K+ gradient: (i) large conductance (BKCa; approximately 200 pS) channels blocked by 2 mM external TEA; (ii) intermediate conductance (IKCa; approximately 39 pS) channels blocked by 2 mM external TEA and inhibited by external apamin (0.5 microM); and (iii) small conductance (SKCa; approximately 10 pS) channels that were not blocked by 5 mM external TEA but were sensitive to extracellular apamin (0.5 microM). 4. The TEA-resistant SKCa channels were activated by an increase in [Ca2+]i with an EC50 of 1.5 microM and a Hill coefficient of 1.3. 5. P2 purinoceptor agonists 2-methylthioATP (2-MeSATP), 2-chloroATP and ATP (10-50 microM) increased an apamin-sensitive whole-cell outward K+ current. Extrapatch application of 2-MeSATP (20-100 microM) stimulated the apamin-sensitive IKCa and SKCa channels and activated an apamin-sensitive steady outward current at 0 mV. 6. Smooth muscle cells from the mouse ileum possess two apamin-sensitive K+ channels (IKCa and SKCa); of these, the IKCa channels are TEA sensitive while the SKCa channels are TEA resistant. These channels, along with an apamin-sensitive but TEA-resistant steady outward current, may mediate membrane hyperpolarization elicited by purinergic agonists. PMID:9279803

  2. Role of leukotrienes in the regulation of human granulocyte behaviour: dissociation between agonist-induced activation and retardation of apoptosis

    PubMed Central

    Murray, Joanna; Ward, Carol; O'Flaherty, Joseph T; Dransfield, Ian; Haslett, Christopher; Chilvers, Edwin R; Rossi, Adriano G

    2003-01-01

    Since most inflammatory mediators that stimulate granulocyte responsiveness also delay apoptosis, it is often assumed that activation and longevity are causally related. Using isolated human peripheral blood neutrophils and eosinophils, we examined this association by exploiting the proinflammatory lipid mediators, the leukotrienes (LTs), and investigated granulocyte function and apoptosis. LTB4 induced elevation of intracellular free Ca2+ concentration ([Ca2+]i), cell polarisation and retardation of neutrophil apoptosis, although the antiapoptotic effect occurred only at concentrations ⩾300 nM. LTB4-induced activation was attenuated by CP-105,696, a BLT1-specific antagonist suggesting classical LTB4 receptor BLT1 involvement. Despite demonstrating the presence of the neutrophil intracellular LTB4 receptor peroxisome-proliferator activator receptor-α (PPARα) in neutrophils, the selective PPARα agonist WY-14,643 did not mimic LTB4-induced prosurvival effects. LTB4-induced survival, however, also appeared to be mediated by BLT1 since CP-105,696 inhibited the LTB4-mediated antiapoptotic effect. Furthermore, based on studies with CP-105,696 and 5-lipoxygenase inhibitors, lipopolysaccharide (LPS)-, granulocyte–macrophage colony-stimulating factor (GM-CSF)-, dexamethasone- and dibutyryl-cAMP (db-cAMP)-induced delay of neutrophil apoptosis did not involve autocrine production of LTB4. Although LTB4 and LTD4 induced human eosinophil [Ca2+]i elevation and polarization, these LTs did not influence eosinophil apoptosis. Furthermore, LTB4- and LTD4-induced eosinophil activation was attenuated by CP-105,696 and the Cys-LT1 receptor antagonist montelukast, respectively, highlighting specific receptor dependency. Thus, mediator-triggered granulocyte activation and antiapoptotic pathways are distinct events that can be differentially regulated. PMID:12770944

  3. Benzydamine inhibits monocyte migration and MAPK activation induced by chemotactic agonists

    PubMed Central

    Riboldi, Elena; Frascaroli, Giada; Transidico, Pietro; Luini, Walter; Bernasconi, Sergio; Mancini, Francesca; Guglielmotti, Angelo; Milanese, Claudio; Pinza, Mario; Sozzani, Silvano; Mantovani, Alberto

    2003-01-01

    The present study was aimed to investigate the effect of benzydamine, an anti-inflammatory drug devoid of activity on arachidonic acid metabolism, on monocyte chemotaxis and to define the possible biochemical correlates of activity. Benzydamine inhibited monocyte chemotaxis in response to three classes of chemoattractants: the prototypic CC-chemokine CCL2 (MCP-1), the microbial product fMLP and the complement cascade component C5a. The effect was dose-dependent with IC50's of 100, 50 and 45 μM for MCP-1/CCL2, fMLP and C5a, respectively. At the dose of 100 μM, the effect resulted in a 50±10% inhibition of MCP-1/CCL2-induced chemotaxis and 53±6 and 54±5% inhibitions of chemotaxis in response of fMLP and C5a, respectively (n=3). Receptor expression as well as calcium fluxes in response to chemoattractants were not affected by benzydamine. Benzydamine strongly inhibited chemoattractant-induced activation of the mitogen-activated protein kinase (MAPK) ERK1/2, and of its upstream activator kinase MEK1/2. ERK1/12 activation in response to chemoattractants was 89–98% inhibited by a 100 μM concentration of benzydamine with an IC50 of 30 μM. Under the same experimental conditions, pretreatment with 100 μM benzydamine caused a 75–89% inhibition of p38 activation (IC50 25 μM). These results indicate that the anti-inflammatory activity of benzydamine is exerted at multiple levels, including monocyte migration to chemotactic factors associated to a blockage of ERK and p38 MAPK pathways. PMID:12970098

  4. Potent and metabolically stable agonists for protease-activated receptor-2: evaluation of activity in multiple assay systems in vitro and in vivo.

    PubMed

    Kawabata, Atsufumi; Kanke, Toru; Yonezawa, Daiki; Ishiki, Tsuyoshi; Saka, Masako; Kabeya, Mototsugu; Sekiguchi, Fumiko; Kubo, Satoko; Kuroda, Ryotaro; Iwaki, Masahiro; Katsura, Kousaku; Plevin, Robin

    2004-06-01

    To develop potent and metabolically stable agonists for protease-activated receptor-2 (PAR-2), we prepared 2-furoylated (2f) derivatives of native PAR-2-activating peptides, 2f-LIGKV-OH, 2f-LIGRL-OH, 2f-LIGKV-NH(2), and 2f-LIGRL-NH(2), and systematically evaluated their activity in PAR-2-responsive cell lines and tissues. In both HCT-15 cells and NCTC2544 cells overexpressing PAR-2, all furoylated peptides increased cytosolic Ca(2+) levels with a greater potency than the corresponding native peptides, although a similar maximum response was recorded. The absolute potency of each peptide was greater in NCTC2544, possibly due to a higher level of receptor expression. Furthermore, the difference in potency between the 2-furoylated peptides and the native peptides was enhanced when evaluated in the rat superior mesenteric artery and further increased when measuring PAR-2-mediated salivation in ddY mice in vivo. The potency of 2f-LIGRL-NH(2), the most powerful peptide, relative to SLIGKV-OH, was about 100 in the cultured cell Ca(2+) signaling assays, 517 in the vasorelaxation assay, and 1100 in the salivation assay. Amastatin, an aminopeptidase inhibitor, augmented salivation caused by native peptides, but not furoylated peptides. The PAR-2-activating peptides, including the furoylated derivatives, also produced salivation in the wild-type C57BL/6 mice, but not the PAR-2-deficient mice. Our data thus demonstrate that substitution of the N-terminal serine with a furoyl group in native PAR-2-activating peptides dramatically enhances the agonistic activity and decreases degradation by aminopeptidase, leading to development of 2f-LIGRL-NH(2), the most potent peptide. Furthermore, the data from PAR-2-deficient mice provide ultimate evidence for involvement of PAR-2 in salivation and the selective nature of the 2-furoylated peptides. PMID:14976227

  5. Effects of peroxisome proliferator-activated receptor γ agonists on Na+ transport and activity of the kinase SGK1 in epithelial cells from lung and kidney

    PubMed Central

    Wilson, Stuart M; Mansley, Morag K; Getty, Jennet; Husband, Elaine M; Inglis, Sarah K; Hansen, Michael K

    2010-01-01

    Background and purpose: Peroxisome proliferator-activated receptor γ (PPARγ) agonists, such as rosiglitazone and pioglitazone, sensitize cells to insulin, and are therefore used to treat type 2 diabetes. However, in some patients, these drugs induce oedema, and the present study tests the hypothesis that this side effect reflects serum and glucocorticoid-inducible kinase 1 (SGK1)-dependent enhancement of epithelia Na+ absorption. Experimental approach: Na+ absorbing epithelial cells (H441 cells, mpkCCD cells) on permeable membranes were mounted in Ussing chambers, and the effects of rosiglitazone (2 µM) and pioglitazone (10 µM) on transepithelial Na+ absorption were quantified electrometrically. Changes in SGK1 activity were assessed by monitoring phosphorylation of residues within an endogenous protein. Key results: Both cell types absorbed Na+ via an electrogenic process that was enhanced by insulin. In mpkCCD cells, this stimulation of Na+ transport was associated with increased activity of SGK1, whereas insulin regulated Na+ transport in H441 cells through a mechanism that did not involve activation of this kinase. Rosiglitazone and pioglitazone had no discernible effect on transepithelial Na+ absorption in unstimulated or insulin-stimulated cells and failed to alter cellular SGK1 activity. Conclusions and implications: Our results do not support the view that PPARγ agonists stimulate epithelial Na+ absorption or alter the control of cellular SGK1 activity. It is therefore likely that other mechanisms are involved in PPARγ-mediated fluid retention, and a better understanding of these mechanisms may help with the identification of patients likely to develop oedema or heart failure when treated with these drugs. PMID:20105179

  6. Truncation of the peptide sequence in bifunctional ligands with mu and delta opioid receptor agonist and neurokinin 1 receptor antagonist activities

    PubMed Central

    Nair, Padma; Yamamoto, Takashi; Largent-Milnes, Tally M.; Cowell, Scott; Kulkarni, Vinod; Moye, Sharif; Navratilova, Edita; Davis, Peg; Ma, Shou-Wu; Vanderah, Todd W.; Lai, Josephine; Porreca, Frank; Hruby, Victor J.

    2013-01-01

    The optimization and truncation of our lead peptide-derived ligand TY005 possessing eight amino-acid residues was performed. Among the synthesized derivatives, NP30 (Tyr1-DAla2-Gly3-Phe4-Gly5-Trp6-O-[3′,5′-Bzl(CF3)2]) showed balanced and potent opioid agonist as well as substance P antagonist activities in isolated tissue-based assays, together with significant antinociceptive and antiallodynic activities in vivo. PMID:23899615

  7. The Peroxisomal Proliferator-Activated Receptor (PPAR) α Agonist, Fenofibrate, Prevents Fractionated Whole-Brain Irradiation-Induced Cognitive Impairment

    PubMed Central

    Greene-Schloesser, Dana; Payne, Valerie; Peiffer, Ann M.; Hsu, Fang-Chi; Riddle, David R.; Zhao, Weiling; Chan, Michael D.; Metheny-Barlow, Linda; Robbins, Mike E.

    2014-01-01

    We hypothesized that dietary administration of the peroxisomal proliferator-activated receptor α agonist, fenofibrate, to young adult male rats would prevent the fractionated whole-brain irradiation (fWBI)-induced reduction in cognitive function and neurogenesis and prevent the fWBI-induced increase in the total number of activated microglia. Eighty 12–14-week-old young adult male Fischer 344 × Brown Norway rats received either: (1) sham irradiation, (2) 40 Gy of fWBI delivered as two 5 Gy fractions/week for 4 weeks, (3) sham irradiation + dietary fenofibrate (0.2% w/w) starting 7 days prior to irradiation, or (4) fWBI + fenofibrate. Cognitive function was measured 26–29 weeks after irradiation using: (1) the perirhinal cortex (PRh)-dependent novel object recognition task; (2) the hippocampal-dependent standard Morris water maze (MWM) task; (3) the hippocampal-dependent delayed match-to-place version of the MWM task; and (4) a cue strategy preference version of the MWM to distinguish hippocampal from striatal task performance. Neurogenesis was assessed 29 weeks after fWBI in the granular cell layer and subgranular zone of the dentate gyrus using a doublecortin antibody. Microglial activation was assessed using an ED1 antibody in the dentate gyrus and hilus of the hippocampus. A significant impairment in perirhinal cortex-dependent cognitive function was measured after fWBI. In contrast, fWBI failed to alter hippocampal-dependent cognitive function, despite a significant reduction in hippocampal neurogenesis. Continuous administration of fenofibrate prevented the fWBI-induced reduction in perirhinal cortex-dependent cognitive function, but did not prevent the radiation-induced reduction in neurogenesis or the radiation-induced increase in activated microglia. These data suggest that fenofibrate may be a promising therapeutic for the prevention of some modalities of radiation-induced cognitive impairment in brain cancer patients. PMID:24397438

  8. CMHX008, a Novel Peroxisome Proliferator-Activated Receptor γ Partial Agonist, Enhances Insulin Sensitivity In Vitro and In Vivo

    PubMed Central

    Song, Ying; Liu, Zhiguo; Li, Jibin; Gao, Rufei; Zhang, Yuyao; Mei, Hu; Guo, Tingwang; Xiao, Ling; Wang, Bochu; Wu, Chaodong; Xiao, Xiaoqiu

    2014-01-01

    The peroxisome proliferator-activated receptor γ (PPARγ) plays an important role in adipocyte differentiation and insulin sensitivity. Its ligand rosiglitazone has anti-diabetic effect but is frequently accompanied with some severe unwanted effects. The aim of the current study was to compare the anti-diabetic effect of CMHX008, a novel thiazolidinedione-derivative, with rosiglitazone. A luciferase assay was used to evaluate in vitro PPARγ activation. 3T3-L1 cells were used to examine adipocyte differentiation. High fat diet (HFD) mice were used to examine in vivo insulin sensitivity. The mRNA levels were evaluated by real-time RT-PCR. Serum biochemical and hormonal variables were assessed using a clinical chemistry analyser. CMHX008 displayed a moderate PPARγ agonist activity, and promoted 3T3-L1 preadipocyte differentiation with lower activity than rosiglitazone. CMHX008 regulated the expression of PPARγ target genes in a different manner from rosiglitazone. CMHX008 increased the expression and secretion of adiponectin with the similar efficacy as rosiglitazone, but only 25% as potent as rosiglitazone for the induction of adipocyte fatty acid binding protein. Treatment of CMHX008 and rosiglitazone protected mice from high fat diet (HFD)-induced glucose intolerance, hyperinsulinemia and inflammation. CMHX008 reduced the mRNA expression of M1 macrophage markers, and significantly increased the expressions of M2 markers. In conclusion, CMHX008 shared the comparable insulin-sensitizing effects as rosiglitazone with lower adipogenic capacity and might potentially be developed into an effective agent for the treatment of diabetes and metabolic disorders. PMID:25004107

  9. The G Protein-Coupled Estrogen Receptor Agonist G-1 Inhibits Nuclear Estrogen Receptor Activity and Stimulates Novel Phosphoproteomic Signatures.

    PubMed

    Smith, L Cody; Ralston-Hooper, Kimberly J; Ferguson, P Lee; Sabo-Attwood, Tara

    2016-06-01

    Estrogen exerts cellular effects through both nuclear (ESR1 and ESR2) and membrane-bound estrogen receptors (G-protein coupled estrogen receptor, GPER); however, it is unclear if they act independently or engage in crosstalk to influence hormonal responses. To investigate each receptor's role in proliferation, transcriptional activation, and protein phosphorylation in breast cancer cells (MCF-7), we employed selective agonists for ESR1 propyl-pyrazole-triol (PPT), ESR2 diarylpropionitrile (DPN), and GPER (G-1) and also determined the impact of xenoestrogens bisphenol-A (BPA) and genistein on these effects. As anticipated, 17β-estradiol (E2), PPT, DPN, BPA, and genistein each enhanced proliferation and activation of an ERE-driven reporter gene whereas G-1 had no significant impact. However, G-1 significantly reduced E2-, PPT-, DPN-, BPA-, and genistein-induced proliferation and ERE activation at doses greater than 500 nM indicating that G-1 mediated inhibition is not ESR isotype specific. As membrane receptors initiate cascades of phosphorylation events, we performed a global phosphoproteomic analysis on cells exposed to E2 or G-1 to identify potential targets of receptor crosstalk via downstream protein phosphorylation targets. Of the 211 phosphorylated proteins identified, 40 and 13 phosphoproteins were specifically modified by E2 and G-1, respectively. Subnetwork enrichment analysis revealed several processes related to cell cycle were specifically enriched by G-1 compared with E2. Further there existed a number of newly identified proteins that were specifically phosphorylated by G-1. These phosphorylation networks highlight specific proteins that may modulate the inhibitory effects of G-1 and suggest a novel role for interference with nuclear receptor activity driven by E2 and xenoestrogens. PMID:27026707

  10. Inhibition of Doxorubicin-Induced Senescence by PPARδ Activation Agonists in Cardiac Muscle Cells: Cooperation between PPARδ and Bcl6

    PubMed Central

    Barisione, Chiara; Garibaldi, Silvano; Garuti, Anna; Fabbi, Patrizia; Ghigliotti, Giorgio; Brunelli, Claudio

    2012-01-01

    Senescence and apoptosis are two distinct cellular programs that are activated in response to a variety of stresses. Low or high doses of the same stressor, i.e., the anticancer drug doxorubicin, may either induce apoptosis or senescence, respectively, in cardiac muscle cells. We have demonstrated that PPARδ, a ligand-activated transcriptional factor that controls lipid metabolism, insulin sensitivity and inflammation, is also involved in the doxorubicin-induced senescence program. This occurs through its interference with the transcriptional repressor protein B cell lymphoma-6 (Bcl6). Low doses of doxorubicin increase the expression of PPARδ that sequesters Bcl6, thus preventing it from exerting its anti-senescent effects. We also found that L-165041, a specific PPARδ activator, is highly effective in protecting cardiomyocytes from doxorubicin-induced senescence through a Bcl6 related mechanism. In fact, L-165041 increases Bcl6 expression via p38, JNK and Akt activation, and at the same time it induces the release of Bcl6 from PPARδ, thereby enabling Bcl6 to bind to its target genes. L-165041 also prevented apoptosis induced by higher doses of doxorubicin. However, while experiments performed with siRNA analysis techniques very clearly showed the weight of Bcl6 in the cellular senescence program, no role was found for Bcl6 in the anti-apoptotic effects of L-165041, thus confirming that senescence and apoptosis are two very distinct stress response cellular programs. This study increases our understanding of the molecular mechanism of anthracycline cardiotoxicity and suggests a potential role for PPARδ agonists as cardioprotective agents. PMID:23049957

  11. Isoproterenol Acts as a Biased Agonist of the Alpha-1A-Adrenoceptor that Selectively Activates the MAPK/ERK Pathway

    PubMed Central

    Copik, Alicja. J.; Baldys, Aleksander; Nguyen, Khanh; Sahdeo, Sunil; Ho, Hoangdung; Kosaka, Alan; Dietrich, Paul J.; Fitch, Bill; Raymond, John R.; Ford, Anthony P. D. W.; Button, Donald; Milla, Marcos E.

    2015-01-01

    The α1A-AR is thought to couple predominantly to the Gαq/PLC pathway and lead to phosphoinositide hydrolysis and calcium mobilization, although certain agonists acting at this receptor have been reported to trigger activation of arachidonic acid formation and MAPK pathways. For several G protein-coupled receptors (GPCRs) agonists can manifest a bias for activation of particular effector signaling output, i.e. not all agonists of a given GPCR generate responses through utilization of the same signaling cascade(s). Previous work with Gαq coupling-defective variants of α1A-AR, as well as a combination of Ca2+ channel blockers, uncovered cross-talk between α1A-AR and β2-AR that leads to potentiation of a Gαq-independent signaling cascade in response to α1A-AR activation. We hypothesized that molecules exist that act as biased agonists to selectively activate this pathway. In this report, isoproterenol (Iso), typically viewed as β-AR-selective agonist, was examined with respect to activation of α1A-AR. α1A-AR selective antagonists were used to specifically block Iso evoked signaling in different cellular backgrounds and confirm its action at α1A-AR. Iso induced signaling at α1A-AR was further interrogated by probing steps along the Gαq /PLC, Gαs and MAPK/ERK pathways. In HEK-293/EBNA cells transiently transduced with α1A-AR, and CHO_α1A-AR stable cells, Iso evoked low potency ERK activity as well as Ca2+ mobilization that could be blocked by α1A-AR selective antagonists. The kinetics of Iso induced Ca2+ transients differed from typical Gαq- mediated Ca2+ mobilization, lacking both the fast IP3R mediated response and the sustained phase of Ca2+ re-entry. Moreover, no inositol phosphate (IP) accumulation could be detected in either cell line after stimulation with Iso, but activation was accompanied by receptor internalization. Data are presented that indicate that Iso represents a novel type of α1A-AR partial agonist with signaling bias toward MAPK/ERK signaling cascade that is likely independent of coupling to Gαq. PMID:25606852

  12. Characterization of a Novel Human-Specific STING Agonist that Elicits Antiviral Activity Against Emerging Alphaviruses

    PubMed Central

    Sali, Tina M.; Pryke, Kara M.; Abraham, Jinu; Liu, Andrew; Archer, Iris; Broeckel, Rebecca; Staverosky, Julia A.; Smith, Jessica L.; Al-Shammari, Ahmed; Amsler, Lisi; Sheridan, Kayla; Nilsen, Aaron; Streblow, Daniel N.; DeFilippis, Victor R.

    2015-01-01

    Pharmacologic stimulation of innate immune processes represents an attractive strategy to achieve multiple therapeutic outcomes including inhibition of virus replication, boosting antitumor immunity, and enhancing vaccine immunogenicity. In light of this we sought to identify small molecules capable of activating the type I interferon (IFN) response by way of the transcription factor IFN regulatory factor 3 (IRF3). A high throughput in vitro screen yielded 4-(2-chloro-6-fluorobenzyl)-N-(furan-2-ylmethyl)-3-oxo-3,4-dihydro-2H-benzo[b][1,4]thiazine-6-carboxamide (referred to herein as G10), which was found to trigger IRF3/IFN-associated transcription in human fibroblasts. Further examination of the cellular response to this molecule revealed expression of multiple IRF3-dependent antiviral effector genes as well as type I and III IFN subtypes. This led to the establishment of a cellular state that prevented replication of emerging Alphavirus species including Chikungunya virus, Venezuelan Equine Encephalitis virus, and Sindbis virus. To define cellular proteins essential to elicitation of the antiviral activity by the compound we employed a reverse genetics approach that utilized genome editing via CRISPR/Cas9 technology. This allowed the identification of IRF3, the IRF3-activating adaptor molecule STING, and the IFN-associated transcription factor STAT1 as required for observed gene induction and antiviral effects. Biochemical analysis indicates that G10 does not bind to STING directly, however. Thus the compound may represent the first synthetic small molecule characterized as an indirect activator of human STING-dependent phenotypes. In vivo stimulation of STING-dependent activity by an unrelated small molecule in a mouse model of Chikungunya virus infection blocked viremia demonstrating that pharmacologic activation of this signaling pathway may represent a feasible strategy for combating emerging Alphaviruses. PMID:26646986

  13. Characterization of a Novel Human-Specific STING Agonist that Elicits Antiviral Activity Against Emerging Alphaviruses.

    PubMed

    Sali, Tina M; Pryke, Kara M; Abraham, Jinu; Liu, Andrew; Archer, Iris; Broeckel, Rebecca; Staverosky, Julia A; Smith, Jessica L; Al-Shammari, Ahmed; Amsler, Lisi; Sheridan, Kayla; Nilsen, Aaron; Streblow, Daniel N; DeFilippis, Victor R

    2015-12-01

    Pharmacologic stimulation of innate immune processes represents an attractive strategy to achieve multiple therapeutic outcomes including inhibition of virus replication, boosting antitumor immunity, and enhancing vaccine immunogenicity. In light of this we sought to identify small molecules capable of activating the type I interferon (IFN) response by way of the transcription factor IFN regulatory factor 3 (IRF3). A high throughput in vitro screen yielded 4-(2-chloro-6-fluorobenzyl)-N-(furan-2-ylmethyl)-3-oxo-3,4-dihydro-2H-benzo[b][1,4]thiazine-6-carboxamide (referred to herein as G10), which was found to trigger IRF3/IFN-associated transcription in human fibroblasts. Further examination of the cellular response to this molecule revealed expression of multiple IRF3-dependent antiviral effector genes as well as type I and III IFN subtypes. This led to the establishment of a cellular state that prevented replication of emerging Alphavirus species including Chikungunya virus, Venezuelan Equine Encephalitis virus, and Sindbis virus. To define cellular proteins essential to elicitation of the antiviral activity by the compound we employed a reverse genetics approach that utilized genome editing via CRISPR/Cas9 technology. This allowed the identification of IRF3, the IRF3-activating adaptor molecule STING, and the IFN-associated transcription factor STAT1 as required for observed gene induction and antiviral effects. Biochemical analysis indicates that G10 does not bind to STING directly, however. Thus the compound may represent the first synthetic small molecule characterized as an indirect activator of human STING-dependent phenotypes. In vivo stimulation of STING-dependent activity by an unrelated small molecule in a mouse model of Chikungunya virus infection blocked viremia demonstrating that pharmacologic activation of this signaling pathway may represent a feasible strategy for combating emerging Alphaviruses. PMID:26646986

  14. Antitumor action of the peroxisome proliferator-activated receptor-γ agonist rosiglitazone in hepatocellular carcinoma

    PubMed Central

    BO, QI-FU; SUN, XIU-MEI; LIU, JIN; SUI, XIAO-MEI; LI, GUI-XIN

    2015-01-01

    The inhibition of apoptosis in cancer cells is the major pathological feature of hepatic carcinoma. Rosiglitazone (RGZ), a ligand for peroxisome proliferator-activated receptor γ (PPAR-γ), has been shown to induce apoptosis in hepatic carcinoma cells. However, the mechanism underlying this effect remains to be elucidated. The present study aimed to investigate the effect of RGZ on cell viability and apoptosis, and its mechanisms in cultured HepG2 cells using MTT assay, flow cytometry and western blotting. The results revealed that treatment with RGZ may attenuate HepG2 cell viability and induce the apoptosis of the cells. The mechanism of RGZ-induced apoptosis involves an increase in the level of activated PPAR-γ (p-PPAR-γ) and a decrease in p85 and Akt expression. In addition, the PPAR-γ antagonist GW9662 suppressed the effect of RGZ in the HepG2 cells. Taken together, the results suggest that RGZ induces the apoptosis of HepG2 cells through the activation of PPAR-γ, suppressing the activation of the PI3K/Akt signaling pathway. Such mechanisms may contribute to the favorable effects of treatment using RGZ in HepG2 cells. PMID:26622783

  15. Agonist and Antagonist Muscle EMG Activity Pattern Changes with Skill Acquisition.

    ERIC Educational Resources Information Center

    Engelhorn, Richard

    1983-01-01

    Using electromyography (EMG), researchers studied changes in the control of biceps and triceps brachii muscles that occurred as women college students learned two elbow flexion tasks. Data on EMG activity, angular kinematics, training, and angular displacement were analyzed. (Author/PP)

  16. Biostable agonists that match or exceed activity of native insect kinins on recombinant arthropod GPCRs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The multifunctional arthropod insect kinins share the evolutionarily conserved C-terminal pentapeptide motif Phe-X1-X2-Trp-Gly-NH2, where X1 = His, Asn, Ser, or Tyr and X2 = Ser, Pro, or Ala. Insect kinins regulate diuresis in many species of insects. Compounds with similar biological activity cou...

  17. Platelet activation by a novel solid-phase agonist: effects of VWF immobilized on polystyrene beads.

    PubMed

    Stewart, M W; Etches, W S; Boshkov, L K; Mant, M J; Gordon, P A; Shaw, A R

    1997-05-01

    The interaction between platelets stirred in suspension and VWF immobilized on polystyrene beads was studied. Platelets aggregated and released ATP in response to stirring with VWF beads. Closer examination of the interaction using transmission electron microscopy revealed that the platelets did not simply aggregate with one another but initially adhered to the beads and spread. Platelets in suspension then bound to the bead-adherent platelets forming layers of platelets associated with each bead. The VWF bead-induced platelet activation was completely inhibited by addition of monoclonal antibody (mAb) to GPIb or GPIIb/IIIa. In addition, the activation response was inhibited in the presence of aspirin, indomethacin or the thromboxane receptor antagonist BM13.177, demonstrating a dependence on an intact cyclo-oxygenase pathway. Platelet function studies were carried out on 30 patients with a history of mild bleeding using conventional optical aggregation and VWF bead-induced platelet activation. 12 patients were abnormal by conventional optical aggregometry, whereas 27 patients showed depressed ATP release in response to VWF beads. The results suggest that easily-bruised patients may have a platelet function defect rather than a vascular-based abnormality and that VWF bead-induced platelet activation is a more sensitive test for detecting platelet dysfunction. PMID:9163596

  18. Normal-phase automated mass-directed HPLC purification of a pyrrolobenzodiazepine library with vasopressin agonist activity.

    PubMed

    Kagan, Michael; Chlenov, Michael; Melnikov, Sergey; McConnell, Oliver; Bach, Alvin C; Carter, Guy; Failli, Amedeo; Caggiano, Thomas J; Shumsky, Jay S; Lubda, Dieter

    2009-01-01

    A 23-member library of pyrrolobenzodiazepine derivatives with vasopressin agonist activity was purified on a 100-mg per injection scale using normal-phase (NP) automated mass-directed HPLC. Analytical NP APCI-LC/MS on an experimental monolith silica CN column utilizing gradients of methanol in ethoxynonafluorobutane (hexane-like solvent) was used to provide data on chromatographic purity and ionization of the solutes. The analytical data collected were used to program a preparative LC/MS instrument for "smart" fraction collection based on the protonated molecular ion of the component of interest. Preparative HPLC was carried out on a preparative cyano column with gradients of polar organic solvents in heptane containing n-propylamine as a basic additive. Flow rates twice as high as conventional ones were used for purification of library compounds. Small aliquots of the preparative flow were mixed with makeup solvent and introduced into an APCI source of a quadrupole mass spectrometer, which triggered collection of solutes. Two methods with fixed instrument parameters were used for purification. The system utilized commercially available instrumentation and software, which provided excellent recovery and purity of the library components and appeared to be useful as a fast and efficient alternative to traditional purification technologies based on reversed-phase LC/MS. PMID:19459687

  19. New CD1d agonists: Synthesis and biological activity of 6″-triazole-substituted α-galactosyl ceramides

    PubMed Central

    Jervis, Peter J.; Graham, Lisa M.; Foster, Erin L.; Cox, Liam R.; Porcelli, Steven A.; Besra, Gurdyal S.

    2012-01-01

    Huisgen [3+2] dipolar cycloaddition of 6″-azido-6″-deoxy-α-galactosyl ceramide 11 with a range of alkynes (or a benzyne precursor) yielded a series of triazole-containing α-galactosyl ceramide (α-GalCer) analogues in high yield. These α-GalCer analogues and the precursor azide 11 were tested for their ability to activate iNKT cells and stimulate IL-2 cytokine secretion in vitro, and IFN-γ and IL-4 cytokine secretion in vivo. Some of these analogues, specifically 11, 12b, 12f and 13, were more potent IL-2 stimulators than the prototypical CD1d agonist, α-GalCer 1. In terms of any cytokine bias, most of the triazole-containing analogues exhibited a small Th2 cytokine-biasing response relative to that shown by α-GalCer 1. In contrast, the cycloaddition precursor, namely azide 11, provided a small Th1 cytokine-biasing response. PMID:22652050

  20. Epigenetic Activity of Peroxisome Proliferator-Activated Receptor Gamma Agonists Increases the Anticancer Effect of Histone Deacetylase Inhibitors on Multiple Myeloma Cells

    PubMed Central

    Aouali, Nassera; Broukou, Angeliki; Bosseler, Manon; Keunen, Olivier; Schlesser, Vincent; Janji, Bassam; Palissot, Valerie; Stordeur, Philippe; Berchem, Guy

    2015-01-01

    Epigenetic modifications play a major role in the development of multiple myeloma. We have previously reported that the PPARγ agonist pioglitazone (PIO) enhances, in-vitro, the cytotoxic effect of the Histone deacetylase inhibitor (HDACi), valproic acid (VPA), on multiple myeloma cells. Here, we described the development of a new multiple myeloma mouse model using MOLP8 cells, in order to evaluate the effect of VPA/PIO combination on the progression of myeloma cells, by analyzing the proliferation of bone marrow plasma cells. We showed that VPA/PIO delays the progression of the disease and the invasion of myeloma cells in the bone marrow. Mechanistically, we demonstrated that VPA/PIO increases the cleavage of caspase 3 and PARP, and induces the acetylation of Histone 3 (H3). Furthermore, we provided evidence that PPARγ agonist is able to enhance the action of other HDACi such as Vorinostat or Mocetinostat. Using PPARγ antagonist or siPPARγ, we strongly suggest that, as described during adipogenesis, PIO behaves as an epigenetic regulator by improving the activity of HDACi. This study highlights the therapeutic benefit of PIO/VPA combination, compared to VPA treatment as a single-arm therapy on multiple myeloma and further highlights that such combination may constitute a new promising treatment strategy which should be supported by clinical trials. PMID:26091518

  1. The peroxisome proliferators activated receptor-gamma agonists as therapeutics for the treatment of Alzheimer's disease and mild-to-moderate Alzheimer's disease: a meta-analysis.

    PubMed

    Cheng, Huawei; Shang, Yuping; Jiang, Ling; Shi, Tian-Lu; Wang, Lin

    2016-04-01

    Alzheimer's disease (AD) is a devastating neurodegenerative disease and there is no effective therapy for it. Peroxisome proliferators activated receptor-gamma (PPAR-γ) agonists is a promising therapeutic approach for AD and has been widely studied recently, but no consensus was available up to now. To clarify this point, a meta-analysis was performed. We searched MEDLINE, EMBASE, Cochrane Central database, PUBMED, Springer Link database, SDOS database, CBM, CNKI and Wan fang database by December 2014. Standardized mean difference (SMD), relative risk (RR) and 95% confidence interval (CI) were calculated to assess the strength of the novel therapeutics for AD and mild-to-moderate AD. A total of nine studies comprising 1314 patients and 1311 controls were included in the final meta-analysis. We found the effect of PPAR-γ agonists on Alzheimer's Disease Assessment Scale - Cognitive Subscale (ADAS-cog) scores by using STATA software. There was no evidence for obvious publication bias in the overall meta-analysis. There is insufficient evidence of statistically incognition of AD and mild-to-moderate AD patients have been improved who were treated with PPAR-γ agonists in our research. However, PPAR-γ agonists may be a promising therapeutic approach in future, especially pioglitazone, with large-scale randomized controlled trials to confirm. PMID:26001206

  2. Structure-activity relationship studies of functionally selective kappa opioid receptor agonists that modulate ERK 1/2 phosphorylation while preserving G protein over ?arrestin2 signaling bias.

    PubMed

    Lovell, Kimberly M; Frankowski, Kevin J; Stahl, Edward L; Slauson, Stephen R; Yoo, Euna; Prisinzano, Thomas E; Aub, Jeffrey; Bohn, Laura M

    2015-08-19

    Kappa opioid receptor (KOR) modulation is a promising target for drug discovery efforts due to KOR involvement in pain, depression, and addiction behaviors. We recently reported a new class of triazole KOR agonists that displays significant bias toward G protein signaling over ?arrestin2 recruitment; interestingly, these compounds also induce less activation of ERK1/2 map kinases than the balanced agonist, U69,593. We have identified structure-activity relationships around the triazole scaffold that allows for decreasing the bias for G protein signaling over ERK1/2 activation while maintaining the bias for G protein signaling over ?arrestin2 recruitment. The development of novel compounds, with different downstream signaling outcomes, independent of G protein/?arrestin2 bias, provides a more diverse pharmacological toolset for use in defining complex KOR signaling and elucidating the significance of KOR-mediated signaling. PMID:25891774

  3. The CYP17A1 inhibitor abiraterone exhibits estrogen receptor agonist activity in breast cancer.

    PubMed

    Capper, Cameron P; Larios, José M; Sikora, Matthew J; Johnson, Michael D; Rae, James M

    2016-05-01

    Cytochrome P450 17A1 (CYP17A1) is the requisite enzyme for synthesis of sex steroids, including estrogens and androgens. As such, inhibition of CYP17A1 is a target for inhibiting the growth of hormone-dependent cancers including prostate and breast cancer. Abiraterone, is a first in class potent and selective CYP17A1 inhibitor that has been approved for the treatment of castration-resistant prostate cancer. Given that, androgens are the precursors for estrogen production, it has been proposed that abiraterone could be an effective form of treatment for estrogen receptor (ER)-positive breast cancer, though its utility in this context has yet to be established. Abiraterone has a core steroid-like chemical structure, and so we hypothesized that it may bind to nuclear steroid receptors including ER and have estrogenic activity. We tested this hypothesis by investigating abiraterone's ability to directly modulate ER signaling in breast cancer cell line models. We show that abiraterone directly activates ER, induces ER-target gene expression, and elicits estrogen-response-element reporter activity in the ER-positive cell lines MCF-7 and T47D. Abiraterone also induced cell proliferation by ~2.5-fold over vehicle in both MCF-7 and T47D cells. Importantly, abiraterone-induced cell proliferation and ER-activity was blocked by the selective estrogen receptor downregulator (SERD) fulvestrant, confirming that abiraterone directly acts at the ER. These data suggest that abiraterone should be combined with other ER antagonists when used for the clinical management of ER-positive breast cancer. PMID:27083183

  4. Phospholipid-esterified eicosanoids are generated in agonist-activated human platelets and enhance tissue factor-dependent thrombin generation.

    PubMed

    Thomas, Christopher P; Morgan, Lloyd T; Maskrey, Benjamin H; Murphy, Robert C; Kühn, Hartmut; Hazen, Stanley L; Goodall, Alison H; Hamali, Hassan A; Collins, Peter W; O'Donnell, Valerie B

    2010-03-01

    Here, a group of specific lipids, comprising phosphatidylethanolamine (PE)- or phosphatidylcholine (PC)-esterified 12S-hydroxyeicosatetraenoic acid (12S-HETE), generated by 12-lipoxygenase was identified and characterized. 12S-HETE-PE/PCs were formed within 5 min of activation by thrombin, ionophore, or collagen. Esterified HETE levels generated in response to thrombin were 5.85 +/- 1.42 (PE) or 18.35 +/- 4.61 (PC), whereas free was 65.5 +/- 17.6 ng/4 x 10(7) cells (n = 5 separate donors, mean +/- S.E.). Their generation was stimulated by triggering protease-activated receptors-1 and -4 and signaling via Ca(2+) mobilization secretory phospholipase A2, platelet-activating factor-acetylhydrolase, src tyrosine kinases, and protein kinase C. Stable isotope labeling showed that they form predominantly by esterification that occurs on the same time scale as free acid generation. Unlike free 12S-HETE that is secreted, esterified HETEs remain cell-associated, with HETE-PEs migrating to the outside of the plasma membrane. 12-Lipoxygenase inhibition attenuated externalization of native PE and phosphatidylserine and HETE-PEs. Platelets from a patient with the bleeding disorder, Scott syndrome, did not externalize HETE-PEs, and liposomes supplemented with HETE-PC dose-dependently enhanced tissue factor-dependent thrombin generation in vitro. This suggests a role for these novel lipids in promoting coagulation. Thus, oxidized phospholipids form by receptor/agonist mechanisms, not merely as an undesirable consequence of vascular and inflammatory disease. PMID:20061396

  5. Differential Adjuvant Activities of TLR7 and TLR9 Agonists Inversely Correlate with Nitric Oxide and PGE2 Production

    PubMed Central

    Lee, Jinhee; Martinez, Nuria; West, Kim; Kornfeld, Hardy

    2015-01-01

    Activation of different pattern recognition receptors causes distinct profiles of innate immune responses, which in turn dictate the adaptive immune response. We found that mice had higher CD4+ T cell expansion to an immunogen, ovalbumin, when coadministered with CpG than with CL097 in vivo. To account for this differential adjuvanticity, we assessed the activities of CpG and CL097 on antigen-specific CD4+ T cell expansion in vitro using an OT-II CD4+ T cell/bone marrow-derived dendritic cell (DC) co-culture system. Unexpectedly, ovalbumin-stimulated expansion of OT-II CD4+ T cells in vitro was potently suppressed by both TLR agonists, with CL097 being stronger than CpG. The suppression was synergistically reversed by co-inhibition of cyclooxygenases 1 and 2, and inducible nitric oxide (NO) synthase. In addition, stimulation of OT-II CD4+ T cell/DC cultures with CL097 induced higher levels of CD4+ T cell death than stimulation with CpG, and this CD4+ T cell turnover was reversed by NO and PGE2 inhibition. Consistently, the co-cultures stimulated with CL097 produced higher levels of prostaglandin E2 (PGE2) and NO than stimulation with CpG. CL097 induced higher PGE2 production in DC cultures and higher IFN-γ in the OT-II CD4+ T cell/DC cultures, accounting for the high levels of PGE2 and NO. This study demonstrates that the adjuvant activities of immunostimulatory molecules may be determined by differential induction of negative regulators, including NO and PGE2 suppressing clonal expansion and promoting cell death of CD4+ T cells. PMID:25875128

  6. F15063, a compound with D2/D3 antagonist, 5-HT1A agonist and D4 partial agonist properties: (III) Activity in models of cognition and negative symptoms

    PubMed Central

    Depoortère, R; Auclair, A L; Bardin, L; Slot, L Bruins; Kleven, M S; Colpaert, F; Vacher, B; Newman-Tancredi, A

    2007-01-01

    Background and purpose: The D2/D3 receptor antagonist, D4 receptor partial agonist, and high efficacy 5-HT1A receptor agonist F15063 was shown to be highly efficacious and potent in rodent models of activity against positive symptoms of schizophrenia. However F15063 induced neither catalepsy nor the ‘serotonin syndrome'. Here, we evaluated its profile in rat models predictive of efficacy against negative symptoms/cognitive deficits of schizophrenia. Experimental approach: F15063, given i.p., was assessed in models of behavioural deficits induced by interference with the NMDA/glutamatergic (phencyclidine: PCP) or cholinergic (scopolamine) systems. Key results: Through 5-HT1A activation, F15063 partially alleviated (MED: 0.04 mg kg−1) PCP-induced social interaction deficit between two adult rats, without effect by itself, underlining its potential to combat negative symptoms. At doses above 0.16 mg kg−1, F15063 reduced interaction by itself. F15063 (0.16 mg kg−1) selectively re-established PCP-impaired ‘cognitive flexibility' in a reversal learning task, suggesting potential against adaptability deficits. F15063 (0.04–0.63 mg kg−1) also reversed scopolamine-induced amnesia in a juvenile-adult rat social recognition test, indicative of a pro-cholinergic influence. Activity in this latter test is consistent with its D4 partial agonism, as it was blocked by the D4 antagonist L745,870. Finally, F15063 up to 40 mg kg−1 did not disrupt basal prepulse inhibition of startle reflex in rats, a marker of sensorimotor gating. Conclusions and implications: The balance of D2/D3, D4 and 5-HT1A receptor interactions of F15063 yields a promising profile of activity in models of cognitive deficits and negative symptoms of schizophrenia. PMID:17375085

  7. The spinal antinociceptive activity of the alpha 2-adrenoceptor agonist, xylazine in sheep.

    PubMed Central

    Kyles, A. E.; Waterman, A. E.; Livingston, A.

    1993-01-01

    1. The intrathecal administration of xylazine (100 micrograms), via a chronic indwelling, cervical intrathecal catheter, produced a marked elevation of the mechanical nociceptive thresholds in the sheep. This antinociceptive effect was abolished by the prior intrathecal administration of the alpha 2-adrenoceptor antagonist, idazoxan. 2. The intrathecal administration of the selective alpha 2-antagonists, idazoxan (100 micrograms) and RX811059 (33 micrograms), significantly attenuated the antinociceptive activity of intravenous xylazine, with a 60-65% reduction in the area under the antinociceptive curve. The intrathecal administration of the antagonists alone had no significant effect on nociceptive thresholds. 3. Examination of the distribution of tritiated idazoxan (25 microCi in 100 microliters) indicated that the site of action of the drug was limited to the cervical spinal cord after intrathecal administration. 4. These studies demonstrate that a significant proportion of the antinociceptive effect of systemically administered xylazine is mediated by spinal alpha 2-adrenoceptors. PMID:8097956

  8. Circumventing seizure activity in a series of G protein coupled receptor 119 (GPR119) agonists.

    PubMed

    Scott, James S; Bowker, Suzanne S; Brocklehurst, Katy J; Brown, Hayley S; Clarke, David S; Easter, Alison; Ertan, Anne; Goldberg, Kristin; Hudson, Julian A; Kavanagh, Stefan; Laber, David; Leach, Andrew G; MacFaul, Philip A; Martin, Elizabeth A; McKerrecher, Darren; Schofield, Paul; Svensson, Per H; Teague, Joanne

    2014-11-13

    Agonism of GPR119 is viewed as a potential therapeutic approach for the treatment of type II diabetes and other elements of metabolic syndrome. During progression of a previously disclosed candidate 1 through mice toxicity studies, we observed tonic-clonic convulsions in several mice at high doses. An in vitro hippocampal brain slice assay was used to assess the seizure liability of subsequent compounds, leading to the identification of an aryl sulfone as a replacement for the 3-cyano pyridyl group. Subsequent optimization to improve the overall profile, specifically with regard to hERG activity, led to alkyl sulfone 16. This compound did not cause tonic-clonic convulsions in mice, had a good pharmacokinetic profile, and displayed in vivo efficacy in murine models. Importantly, it was shown to be effective in wild-type (WT) but not GPR119 knockout (KO) animals, consistent with the pharmacology observed being due to agonism of GPR119. PMID:25286150

  9. Conformational Restriction Leading to a Selective CB2 Cannabinoid Receptor Agonist Orally Active Against Colitis

    PubMed Central

    2014-01-01

    The CB2 cannabinoid receptor has been implicated in the regulation of intestinal inflammation. Following on from the promising activity of a series of 4-oxo-1,4-dihydroquinoline-3-carboxamide, we developed constrained analogues based on a 2H-pyrazolo[4,3-c]quinolin-3(5H)-one scaffold, with improved affinity for the hCB2 receptor and had very high selectivity over the hCB1 receptor. Importantly, the lead of this series (26, hCB2: Ki = 0.39 nM, hCB1: Ki > 3000 nM) was found to protect mice against experimental colitis after oral administration. PMID:25699149

  10. Protein Kinase D and Gβγ Subunits Mediate Agonist-evoked Translocation of Protease-activated Receptor-2 from the Golgi Apparatus to the Plasma Membrane.

    PubMed

    Jensen, Dane D; Zhao, Peishen; Jimenez-Vargas, Nestor N; Lieu, TinaMarie; Gerges, Marina; Yeatman, Holly R; Canals, Meritxell; Vanner, Stephen J; Poole, Daniel P; Bunnett, Nigel W

    2016-05-20

    Agonist-evoked endocytosis of G protein-coupled receptors has been extensively studied. The mechanisms by which agonists stimulate mobilization and plasma membrane translocation of G protein-coupled receptors from intracellular stores are unexplored. Protease-activated receptor-2 (PAR2) traffics to lysosomes, and sustained protease signaling requires mobilization and plasma membrane trafficking of PAR2 from Golgi stores. We evaluated the contribution of protein kinase D (PKD) and Gβγ to this process. In HEK293 and KNRK cells, the PAR2 agonists trypsin and 2-furoyl-LIGRLO-NH2 activated PKD in the Golgi apparatus, where PKD regulates protein trafficking. PAR2 activation induced translocation of Gβγ, a PKD activator, to the Golgi apparatus, determined by bioluminescence resonance energy transfer between Gγ-Venus and giantin-Rluc8. Inhibitors of PKD (CRT0066101) and Gβγ (gallein) prevented PAR2-stimulated activation of PKD. CRT0066101, PKD1 siRNA, and gallein all inhibited recovery of PAR2-evoked Ca(2+) signaling. PAR2 with a photoconvertible Kaede tag was expressed in KNRK cells to examine receptor translocation from the Golgi apparatus to the plasma membrane. Irradiation of the Golgi region (405 nm) induced green-red photo-conversion of PAR2-Kaede. Trypsin depleted PAR2-Kaede from the Golgi apparatus and repleted PAR2-Kaede at the plasma membrane. CRT0066101 inhibited PAR2-Kaede translocation to the plasma membrane. CRT0066101 also inhibited sustained protease signaling to colonocytes and nociceptive neurons that naturally express PAR2 and mediate protease-evoked inflammation and nociception. Our results reveal a major role for PKD and Gβγ in agonist-evoked mobilization of intracellular PAR2 stores that is required for sustained signaling by extracellular proteases. PMID:27030010

  11. In vitro and in vivo characterization of A-796260: a selective cannabinoid CB2 receptor agonist exhibiting analgesic activity in rodent pain models

    PubMed Central

    Yao, B B; Hsieh, G C; Frost, J M; Fan, Y; Garrison, T R; Daza, A V; Grayson, G K; Zhu, C Z; Pai, M; Chandran, P; Salyers, A K; Wensink, E J; Honore, P; Sullivan, J P; Dart, M J; Meyer, M D

    2007-01-01

    Background and purpose: Selective cannabinoid CB2 receptor agonists have demonstrated analgesic activity across multiple preclinical pain models. AM1241 is an indole derivative that exhibits high affinity and selectivity for the CB2 binding site and broad spectrum analgesic activity in rodent models, but is not an antagonist of CB2 in vitro functional assays. Additionally, its analgesic effects are μ-opioid receptor-dependent. Herein, we describe the in vitro and in vivo pharmacological properties of A-796260, a novel CB2 agonist. Experimental approach: A-796260 was characterized in radioligand binding and in vitro functional assays at rat and human CB1 and CB2 receptors. The behavioural profile of A-796260 was assessed in models of inflammatory, post-operative, neuropathic, and osteoarthritic (OA) pain, as well as its effects on motor activity. The receptor specificity was confirmed using selective CB1, CB2 and μ-opioid receptor antagonists. Key results: A-796260 exhibited high affinity and agonist efficacy at human and rat CB2 receptors, and was selective for the CB2 vs CB1 subtype. Efficacy in models of inflammatory, post-operative, neuropathic and OA pain was demonstrated, and these activities were selectively blocked by CB2, but not CB1 or μ-opioid receptor-selective antagonists. Efficacy was achieved at doses that had no significant effects on motor activity. Conclusions and implications: These results further confirm the therapeutic potential of CB2 receptor-selective agonists for the treatment of pain. In addition, they demonstrate that A-796260 may be a useful new pharmacological compound for further studying CB2 receptor pharmacology and for evaluating its role in the modulation of pain. PMID:17994110

  12. Therapeutic potential of the dual peroxisome proliferator activated receptor (PPAR)α/γ agonist aleglitazar in attenuating TNF-α-mediated inflammation and insulin resistance in human adipocytes.

    PubMed

    Massaro, Marika; Scoditti, Egeria; Pellegrino, Mariangela; Carluccio, Maria Annunziata; Calabriso, Nadia; Wabitsch, Martin; Storelli, Carlo; Wright, Matthew; De Caterina, Raffaele

    2016-05-01

    Adipose tissue inflammation is a mechanistic link between obesity and its related sequelae, including insulin resistance and type 2 diabetes. Dual ligands of peroxisome proliferator activated receptor (PPAR)α and γ, combining in a single molecule the metabolic and inflammatory-regulatory properties of α and γ agonists, have been proposed as a promising therapeutic strategy to antagonize adipose tissue inflammation. Here we investigated the effects of the dual PPARα/γ agonist aleglitazar on human adipocytes challenged with inflammatory stimuli. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were treated with aleglitazar or - for comparison - the selective agonists for PPARα or γ fenofibrate or rosiglitazone, respectively, for 24h before stimulation with TNF-α. Aleglitazar, at concentrations as low as 10nmol/L, providing the half-maximal transcriptional activation of both PPARα and PPARγ, reduced the stimulated expression of several pro-inflammatory mediators including interleukin (IL)-6, the chemokine CXC-L10, and monocyte chemoattractant protein (MCP)-1. Correspondingly, media from adipocytes treated with aleglitazar reduced monocyte migration, consistent with suppression of MCP-1 secretion. Under the same conditions, aleglitazar also reversed the TNF-α-mediated suppression of insulin-stimulated ser473 Akt phosphorylation and decreased the TNF-α-induced ser312 IRS1 phosphorylation, two major switches in insulin-mediated metabolic activities, restoring glucose uptake in insulin-resistant adipocytes. Such effects were similar to those obtainable with a combination of single PPARα and γ agonists. In conclusion, aleglitazar reduces inflammatory activation and dysfunction in insulin signaling in activated adipocytes, properties that may benefit diabetic and obese patients. The effect of aleglitazar was consistent with dual PPARα and γ agonism, but with no evidence of synergism. PMID:26976796

  13. Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles

    SciTech Connect

    Sakar, M.; Balakumar, S.; Saravanan, P.; Jaisankar, S. N.

    2013-02-05

    Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite. When this composite was annealed to 650 Degree-Sign C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and {gamma}-Fe{sub 2}O{sub 3} phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

  14. Molecular Engineering of Organophosphate Hydrolysis Activity from a Weak Promiscuous Lactonase Template

    PubMed Central

    Meier, Monika M; Rajendran, Chitra; Malisi, Christoph; Fox, Nicholas G; Xu, Chengfu; Schlee, Sandra; Barondeau, David P; Höcker, Birte; Sterner, Reinhard; Raushel, Frank M

    2013-01-01

    Rapid evolution of enzymes provides unique molecular insights into the remarkable adaptability of proteins and helps to elucidate the relationship between amino acid sequence, structure and function. We interrogated the evolution of the phosphotriesterase from Pseudomonas diminuta (PdPTE), which hydrolyzes synthetic organophosphates with remarkable catalytic efficiency. PTE is thought to be an evolutionarily “young” enzyme and it has been postulated that it has evolved from members of the phosphotriesterase-like lactonase (PLL) family that show promiscuous organophosphate degrading activity. Starting from a weakly promiscuous PLL scaffold (Dr0930 from Deinococcus radiodurans), we designed an extremely efficient organophosphate hydrolase (OPH) with broad substrate specificity using rational and random mutagenesis in combination with in vitro activity screening. The OPH activity for seven organophosphate substrates was simultaneously enhanced by up to five orders of magnitude, achieving absolute values of catalytic efficiencies up to 106 M−1 s−1. Structural and computational analyses identified the molecular basis for the enhanced OPH activity of the engineered PLL variants and demonstrated that OPH catalysis in PdPTE and the engineered PLL differ significantly in the mode of substrate binding. PMID:23837603

  15. Investigation of a Bubble Detector based on Active Electrolocation of Weakly Electric Fish

    NASA Astrophysics Data System (ADS)

    Mohan, M.; Mayekar, K.; Zhou, R.; von der Emde, G.; Bousack, H.

    2013-04-01

    Weakly electric fish employ active electrolocation for navigation and object detection. They emit an electric signal with their electric organ in the tail and sense the electric field with electroreceptors that are distributed over their skin. We adopted this principle to design a bubble detector that can detect gas bubbles in a fluid or, in principle, objects with different electric conductivity than the surrounding fluid. The evaluation of the influence of electrode diameter on detecting a given bubble size showed that the signal increases with electrode diameter. Therefore it appears that this detector will be more appropriate for large sized applications such as bubble columns than small sized applications such as bubble detectors in dialysis.

  16. Development of a potent and selective GPR7 (NPBW1) agonist: a systematic structure-activity study of neuropeptide B.

    PubMed

    Kanesaka, Maki; Matsuda, Masao; Hirano, Atsushi; Tanaka, Kenichi; Kanatani, Akio; Tokita, Shigeru

    2007-06-01

    Neuropeptide B (NPB) has been recently identified as an endogenous ligand for GPR7 (NPBW1) and GPR8 (NPBW2) and has been shown to possess a relatively high selectivity for GPR7. In order to identify useful experimental tools to address physiological roles of GPR7, we synthesized a series of NPB analogs based on modification of an unbrominated form of 23 amino acids with amidated C-terminal, Br(-)NPB-23-NH(2). We confirmed that truncation of the N-terminal Trp residue resulted in almost complete loss of the binding affinity of NPB for GPR7 and GPR8, supporting the special importance of this residue for binding. Br(-)NPB-23-NH2 analogs in which each amino acid in positions 4, 5, 7, 8, 9, 10, 12 and 21 was replaced with alanine or glycine exhibited potent binding affinity comparable to the parent peptide. In contrast, replacement of Tyr(11) with alanine reduced the binding affinity for both GPR7 and GPR8 four fold. Of particular interest, several NPB analogs in which the consecutive amino acids from Pro4 to Val(13) were replaced with several units of 5-aminovaleric acid (Ava) linkers retained their potent affinity for GPR7. Furthermore, these Ava-substituted NPB analogs exhibited potent agonistic activities for GPR7 expressed in HEK293 cells. Among the Ava-substituted NPB analogs, analog 15 (Ava-5) and 17 (Ava-3) exhibited potency comparable to the parent peptide for GPR7 with significantly reduced activity for GPR8, resulting in high selectivity for GPR7. These highly potent and selective NPB analogs may be useful pharmacological tools to investigate the physiological and pharmacological roles of GPR7. PMID:17486669

  17. GLP-1 Receptor Agonists and the Thyroid: C-Cell Effects in Mice Are Mediated via the GLP-1 Receptor and not Associated with RET Activation

    PubMed Central

    Knauf, Jeffrey A.; Gotfredsen, Carsten; Pilling, Andrew; Sjögren, Ingrid; Andersen, Søren; Andersen, Lene; Sietske de Boer, Anne; Manova, Katia; Barlas, Afsar; Vundavalli, Sushil; Nyborg, Niels C. Berg; Bjerre Knudsen, Lotte; Moelck, Anne Marie

    2012-01-01

    Liraglutide and exenatide are glucagon-like peptide receptor (GLP-1R) agonists used in the treatment of type 2 diabetes. Both molecules have been associated with the development of thyroid C-cell tumors after lifetime exposure in rodents. Previously, it has been reported that these tumors are preceded by increased plasma calcitonin and C-cell hyperplasia. We can now document that the murine C-cell effects are mediated via GLP-1R. Thus, 13 wk of continuous exposure to GLP-1R agonists was associated with marked increases in plasma calcitonin and in the incidence of C-cell hyperplasia in wild-type mice. In contrast, similar effects were not seen in GLP-1R knockout mice. Human C-cell cancer is often caused by activating mutations in the rearranged-during-transfection (RET) protooncogene. We developed an immunohistochemical method to assess RET activation in tissues. Liraglutide dosing to mice was not found to activate RET. Further evaluation of the signaling pathways demonstrated that liraglutide increased ribosomal S6, but not MAPK kinase, phosphorylation. These observations are consistent with effects of GLP-1R agonists on rodent C cells being mediated via mammalian target of rapamycin activation in a RET- and MAPK-independent manner. PMID:22234463

  18. Dendritic cells and NK cells stimulate bystander T cell activation in response to TLR agonists through secretion of IFN-alpha beta and IFN-gamma.

    PubMed

    Kamath, Arun T; Sheasby, Christopher E; Tough, David F

    2005-01-15

    Recognition of conserved features of infectious agents by innate pathogen receptors plays an important role in initiating the adaptive immune response. We have investigated early changes occurring among T cells after injection of TLR agonists into mice. Widespread, transient phenotypic activation of both naive and memory T cells was observed rapidly after injection of molecules acting through TLR3, -4, -7, and -9, but not TLR2. T cell activation was shown to be mediated by a combination of IFN-alphabeta, secreted by dendritic cells (DCs), and IFN-gamma, secreted by NK cells; notably, IFN-gamma-secreting NK cells expressed CD11c and copurified with DCs. Production of IFN-gamma by NK cells could be stimulated by DCs from TLR agonist-injected mice, and although soluble factors secreted by LPS-stimulated DCs were sufficient to induce IFN-gamma, maximal IFN-gamma production required both direct contact of NK cells with DCs and DC-secreted cytokines. In vitro, IFN-alphabeta, IL-18, and IL-12 all contributed to DC stimulation of NK cell IFN-gamma, whereas IFN-alphabeta was shown to be important for induction of T cell bystander activation and NK cell IFN-gamma production in vivo. The results delineate a pathway involving innate immune mediators through which TLR agonists trigger bystander activation of T cells. PMID:15634897

  19. Distinct properties of telmisartan on agonistic activities for peroxisome proliferator-activated receptor γ among clinically used angiotensin II receptor blockers: drug-target interaction analyses.

    PubMed

    Kakuta, Hirotoshi; Kurosaki, Eiji; Niimi, Tatsuya; Gato, Katsuhiko; Kawasaki, Yuko; Suwa, Akira; Honbou, Kazuya; Yamaguchi, Tomohiko; Okumura, Hiroyuki; Sanagi, Masanao; Tomura, Yuichi; Orita, Masaya; Yonemoto, Takako; Masuzaki, Hiroaki

    2014-04-01

    A proportion of angiotensin II type 1 receptor blockers (ARBs) improves glucose dyshomeostasis and insulin resistance in a clinical setting. Of these ARBs, telmisartan has the unique property of being a partial agonist for peroxisome proliferator-activated receptor γ (PPARγ). However, the detailed mechanism of how telmisartan acts on PPARγ and exerts its insulin-sensitizing effect is poorly understood. In this context, we investigated the agonistic activity of a variety of clinically available ARBs on PPARγ using isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) system. Based on physicochemical data, we then reevaluated the metabolically beneficial effects of telmisartan in cultured murine adipocytes. ITC and SPR assays demonstrated that telmisartan exhibited the highest affinity of the ARBs tested. Distribution coefficient and parallel artificial membrane permeability assays were used to assess lipophilicity and cell permeability, for which telmisartan exhibited the highest levels of both. We next examined the effect of each ARB on insulin-mediated glucose metabolism in 3T3-L1 preadipocytes. To investigate the impact on adipogenesis, 3T3-L1 preadipocytes were differentiated with each ARB in addition to standard inducers of differentiation for adipogenesis. Telmisartan dose-dependently facilitated adipogenesis and markedly augmented the mRNA expression of adipocyte fatty acid-binding protein (aP2), accompanied by an increase in the uptake of 2-deoxyglucose and protein expression of glucose transporter 4 (GLUT4). In contrast, other ARBs showed only marginal effects in these experiments. In accordance with its highest affinity of binding for PPARγ as well as the highest cell permeability, telmisartan superbly activates PPARγ among the ARBs tested, thereby providing a fresh avenue for treating hypertensive patients with metabolic derangement. PMID:24424487

  20. Activation of Relaxin Family Receptor 1 from Different Mammalian Species by Relaxin Peptide and Small-Molecule Agonist ML290

    PubMed Central

    Huang, Zaohua; Myhr, Courtney; Bathgate, Ross A. D.; Ho, Brian A.; Bueno, Amaya; Hu, Xin; Xiao, Jingbo; Southall, Noel; Barnaeva, Elena; Agoulnik, Irina U.; Marugan, Juan J.; Ferrer, Marc; Agoulnik, Alexander I.

    2015-01-01

    Relaxin peptide (RLN), which signals through the relaxin family peptide 1 (RXFP1) GPCR receptor, has shown therapeutic effects in an acute heart failure clinical trial. We have identified a small-molecule agonist of human RXFP1, ML290; however, it does not activate the mouse receptor. To find a suitable animal model for ML290 testing and to gain mechanistic insights into the interaction of various ligands with RXFP1, we have cloned rhesus macaque, pig, rabbit, and guinea pig RXFP1s and analyzed their activation by RLN and ML290. HEK293T cells expressing macaque or pig RXFP1 responded to relaxin and ML290 treatment as measured by an increase of cAMP production. Guinea pig RXFP1 responded to relaxin but had very low response to ML290 treatment only at highest concentrations used. The rabbit RXFP1 amino acid sequence was the most divergent, with a number of unique substitutions within the ectodomain and the seven-transmembrane domain (7TM). Two splice variants of rabbit RXFP1 derived through alternative splicing of the fourth exon were identified. In contrast to the other species, rabbit RXFP1s were activated by ML290, but not with human, pig, mouse, or rabbit RLNs. Using FLAG-tagged constructs, we have shown that both rabbit RXFP1 variants are expressed on the cell surface. No binding of human Eu-labeled RLN to rabbit RXFP1 was detected, suggesting that in this species, RXFP1 might be non-functional. We used chimeric rabbit–human and guinea pig–human constructs to identify regions important for RLN or ML290 receptor activation. Chimeras with the human ectodomain and rabbit 7TM domain were activated by RLN, whereas substitution of part of the guinea pig 7TM domain with the human sequence only partially restored ML290 activation, confirming the allosteric mode of action for the two ligands. Our data demonstrate that macaque and pig models can be used for ML290 testing. PMID:26347712

  1. Agonist-trafficking and hallucinogens.

    PubMed

    González-Maeso, Javier; Sealfon, Stuart C

    2009-01-01

    Seven transmembrane domain receptors, also termed G protein-coupled receptors (GPCRs), represent the most common molecular target for therapeutic drugs. The generally accepted pharmacological model for GPCR activation is the ternary complex model, in which GPCRs exist in a dynamic equilibrium between the active and inactive conformational states. However, the demonstration that different agonists sometimes elicit a different relative activation of two signaling pathways downstream of the same receptor has led to a revision of the ternary complex model. According to this agonist- trafficking model, agonists stabilize distinct activated receptor conformations that preferentially activate specific signaling pathways. Hallucinogenic drugs and non-hallucinogenic drugs represent an attractive experimental system with which to study agonist-trafficking of receptor signaling. Thus many of the behavioral responses induced by hallucinogenic drugs, such as lysergic acid diethylamide (LSD), psilocybin or mescaline, depend on activation of serotonin 5-HT(2A) receptors (5-HT2ARs). In contrast, this neuropsychological state in humans is not induced by closely related chemicals, such as lisuride or ergotamine, despite their similar in vitro activity at the 5-HT2AR. In this review, we summarize the current knowledge, as well as unresolved questions, regarding agonist-trafficking and the mechanism of action of hallucinogenic drugs. PMID:19275609

  2. Pharmacological activity of C10-substituted analogs of the high-affinity kainate receptor agonist dysiherbaine

    PubMed Central

    Lash-Van Wyhe, L. Leanne; Postila, Pekka A.; Tsubone, Koichi; Sasaki, Makoto; Pentikäinen, Olli T.; Sakai, Ryuichi; Swanson, Geoffrey T.

    2009-01-01

    Summary Kainate receptor antagonists have potential as therapeutic agents in a number of neuropathologies. Synthetic modification of the convulsant marine toxin neodysiherbaine A (NDH) previously yielded molecules with a diverse set of pharmacological actions on kainate receptors. Here we characterize three new synthetic analogs of NDH that contain substituents at the C10 position in the pyran ring of the marine toxin. The analogs exhibited high affinity binding to the GluK1 (GluR5) subunit and lower affinity binding to GluK2 (GluR6) and GluK3 (GluR7) subunits in radioligand displacement assays with recombinant kainate and AMPA receptors. As well, the natural toxin NDH exhibited ∼100-fold selectivity for GluK2 over GluK3 subunits, which was attributable to the C8 hydroxyl group in NDH. We used molecular dynamic simulations to determine the specific interactions between NDH and residues within the ligand-binding domains of these two kainate receptor subunits that contribute to the divergent apparent affinities for the compound. These data demonstrate that interactions with the GluK1 subunit are preserved in analogs with substitutions at C10 in NDH and further reveal the determinants of selectivity and pharmacological activity of molecules acting on kainate receptor subunits, which could aid in design of additional compounds that target these receptors. PMID:19962997

  3. Mitochondrial impairment by PPAR agonists and statins identified via immunocaptured OXPHOS complex activities and respiration

    SciTech Connect

    Nadanaciva, Sashi; Dykens, James A.; Bernal, Autumn; Capaldi, Roderick A.; Will, Yvonne

    2007-09-15

    Mitochondrial impairment is increasingly implicated in the etiology of toxicity caused by some thiazolidinediones, fibrates, and statins. We examined the effects of members of these drug classes on respiration of isolated rat liver mitochondria using a phosphorescent oxygen sensitive probe and on the activity of individual oxidative phosphorylation (OXPHOS) complexes using a recently developed immunocapture technique. Of the six thiazolidinediones examined, ciglitazone, troglitazone, and darglitazone potently disrupted mitochondrial respiration. In accord with these data, ciglitazone and troglitazone were also potent inhibitors of Complexes II + III, IV, and V, while darglitazone predominantly inhibited Complex IV. Of the six statins evaluated, lovastatin, simvastatin, and cerivastatin impaired mitochondrial respiration the most, with simvastatin and lovastatin impairing multiple OXPHOS Complexes. Within the class of fibrates, gemfibrozil more potently impaired respiration than fenofibrate, clofibrate, or ciprofibrate. Gemfibrozil only modestly inhibited Complex I, fenofibrate inhibited Complexes I, II + III, and V, and clofibrate inhibited Complex V. Our findings with the two complementary methods indicate that (1) some members of each class impair mitochondrial respiration, whereas others have little or no effect, and (2) the rank order of mitochondrial impairment accords with clinical adverse events observed with these drugs. Since the statins are frequently co-prescribed with the fibrates or thiazolidinediones, various combinations of these three drug classes were also analyzed for their mitochondrial effects. In several cases, the combination additively uncoupled or inhibited respiration, suggesting that some combinations are more likely to yield clinically relevant drug-induced mitochondrial side effects than others.

  4. A pivotal role of FOS-mediated BECN1/Beclin 1 upregulation in dopamine D2 and D3 receptor agonist-induced autophagy activation

    PubMed Central

    Wang, Jian-Da; Cao, Yu-Lan; Li, Qian; Yang, Ya-Ping; Jin, Mengmeng; Chen, Dong; Wang, Fen; Wang, Guang-Hui; Qin, Zheng-Hong; Hu, Li-Fang; Liu, Chun-Feng

    2015-01-01

    Autophagy dysfunction is implicated in the pathogenesis of Parkinson disease (PD). BECN1/Beclin 1 acts as a critical regulator of autophagy and other cellular processes; yet, little is known about the function and regulation of BECN1 in PD. In this study, we report that dopamine D2 and D3 receptor (DRD2 and DRD3) activation by pramipexole and quinpirole could enhance BECN1 transcription and promote autophagy activation in several cell lines, including PC12, MES23.5 and differentiated SH-SY5Y cells, and also in tyrosine hydroxylase positive primary midbrain neurons. Moreover, we identified a novel FOS (FBJ murine osteosarcoma viral oncogene homolog) binding sequence (5′-TGCCTCA-3′) in the rat and human Becn1/BECN1 promoter and uncovered an essential role of FOS binding in the enhancement of Becn1 transcription in PC12 cells in response to the dopamine agonist(s). In addition, we demonstrated a critical role of intracellular Ca2+ elevation, followed by the enhanced phosphorylation of CAMK4 (calcium/calmodulin-dependent protein kinase IV) and CREB (cAMP responsive element binding protein) in the increases of FOS expression and autophagy activity. More importantly, pramipexole treatment ameliorated the SNCA/α-synuclein accumulation in rotenone-treated PC12 cells that overexpress wild-type or A53T mutant SNCA by promoting autophagy flux. This effect was also demonstrated in the substantia nigra and the striatum of SNCAA53T transgenic mice. The inhibition of SNCA accumulation by pramipexole was attenuated by cotreatment with the DRD2 and DRD3 antagonists and Becn1 siRNAs. Thus, our findings suggest that DRD2 and DRD3 agonist(s) may induce autophagy activation via a BECN1-dependent pathway and have the potential to reduce SNCA accumulation in PD. PMID:26649942

  5. Classification of active and weakly active ST inhibitors of HIV-1 integrase using a support vector machine.

    PubMed

    Yan, Aixia; Xuan, Shouyi; Hu, Xiaoying

    2012-12-01

    Using a support vector machine (SVM), two computational models were built to predict whether a compound is an active or weakly active strand transfer (ST) inhibitor based on a dataset of 1257 ST inhibitors of HIV-1 integrase. The model built with MACCS fingerprints gave a prediction accuracy of 91.82% and a Matthews Correlation Coeffiient (MCC) of 0.73 on test set, and the model built with 40 MOE descriptors gave a prediction accuracy of 93.64% and an MCC of 0.79 on test set. Some molecular properties such as electrostatic properties, van der Waals surface area, hydrogen bond properties and the number of fluorine atoms are important factors influencing the interactions between the inhibitor and the integrase. Some scaffolds like β-diketo acid and its derivatives, naphthyridine carboxamide or the isosteric of it and pyrimidionones may play crucial rule to the activity of the HIV-1 integrase inhibitors. PMID:22934952

  6. Agonist and antagonist properties of antipsychotics at human dopamine D4.4 receptors: G-protein activation and K+ channel modulation in transfected cells.

    PubMed

    Newman-Tancredi, Adrian; Heusler, Peter; Martel, Jean-Claude; Ormière, Anne-Marie; Leduc, Nathalie; Cussac, Didier

    2008-05-01

    Interaction at dopamine D4 receptors may improve cognitive function, which is highly impaired in individuals with schizophrenia, but comparative studies of recent antipsychotics in cellular models of D4 receptor activation are lacking. Here, we report the in-vitro profile of over 30 ligands at recombinant hD4.4 receptors. In [35S]GTPgammaS binding experiments using membranes of CHO-hD4.4 cells, apomorphine, preclamol and the selective D4 agonists, ABT724, CP226269, Ro-10-5824 and PD168077, behaved as partial agonists (Emax 20-60% vs. dopamine), whereas L745870 and RBI257, displayed antagonist properties. The 'conventional' antipsychotic, haloperidol and the 'atypicals', clozapine and risperidone, exhibited antagonist properties, while 'third generation' compounds bifeprunox, SLV313 and F15063, acted as partial agonists (10-30%). Aripiprazole and SSR181507 slightly stimulated [35S]GTPgammaS binding at micromolar concentrations. In Xenopus laevis oocytes co-expressing hD4.4 receptors with G-protein-coupled inwardly rectifying potassium (GIRK) channels, apomorphine, preclamol, ABT724, CP226269, and PD168077 stimulated GIRK currents (Emax 70-80%). The 5-HT1A receptor ligands, WAY100635 and flibanserin, also exhibited partial agonist activity (30% and 15%, respectively). Haloperidol, clozapine, olanzapine and nemonapride did not stimulate GIRK currents, whereas aripiprazole, bifeprunox, SLV313 and F15063, but not SSR181507, exhibited partial agonism (Emax 20-35%). In-vitro responses depended on experimental conditions: increasing NaCl concentration (30 mm to 100 mm) reduced agonist efficacy in [35S]GTPgammaS binding, whereas decreasing the amount of hD4.4 cRNA injected into oocytes (from 2.0 to 0.5 ng/oocyte) reduced agonist efficacy of several compounds. These data indicate that, unlike conventional or 'atypical' antipsychotics, several 'third generation' agents display D4 receptor partial agonism that may be sufficient to influence physiological D4 receptor activity in vivo. PMID:17897483

  7. Clobetasol and Halcinonide Act as Smoothened Agonists to Promote Myelin Gene Expression and RxRγ Receptor Activation

    PubMed Central

    De Nardis, Velia; Di Giandomenico, Daniele; Lucisano, Giuseppe; Scardapane, Marco; Poma, Anna; Ragnini-Wilson, Antonella

    2015-01-01

    One of the causes of permanent disability in chronic multiple sclerosis patients is the inability of oligodendrocyte progenitor cells (OPCs) to terminate their maturation program at lesions. To identify key regulators of myelin gene expression acting at the last stages of OPC maturation we developed a drug repositioning strategy based on the mouse immortalized oligodendrocyte (OL) cell line Oli-neu brought to the premyelination stage by stably expressing a key factor regulating the last stages of OL maturation. The Prestwick Chemical Library® of 1,200 FDA-approved compound(s) was repositioned at three dosages based on the induction of Myelin Basic Protein (MBP) expression. Drug hits were further validated using dosage-dependent reproducibility tests and biochemical assays. The glucocorticoid class of compounds was the most highly represented and we found that they can be divided in three groups according to their efficacy on MBP up-regulation. Since target identification is crucial before bringing compounds to the clinic, we searched for common targets of the primary screen hits based on their known chemical-target interactomes, and the pathways predicted by top ranking compounds were validated using specific inhibitors. Two of the top ranking compounds, Halcinonide and Clobetasol, act as Smoothened (Smo) agonists to up-regulate myelin gene expression in the Oli-neuM cell line. Further, RxRγ activation is required for MBP expression upon Halcinonide and Clobetasol treatment. These data indicate Clobetasol and Halcinonide as potential promyelinating drugs and also provide a mechanistic understanding of their mode of action in the pathway leading to myelination in OPCs. Furthermore, our classification of glucocorticoids with respect to MBP expression provides important novel insights into their effects in the CNS and a rational criteria for their choice in combinatorial therapies in de-myelinating diseases. PMID:26658258

  8. Effects of intravenous administration of neurokinin receptor subtype-selective agonists on gonadotropin-releasing hormone pulse generator activity and luteinizing hormone secretion in goats.

    PubMed

    Yamamura, Takashi; Wakabayashi, Yoshihiro; Ohkura, Satoshi; Navarro, Victor M; Okamura, Hiroaki

    2015-01-01

    Recent evidence suggests that neurokinin B (NKB), a member of the neurokinin (tachykinin) peptide family, plays a pivotal role in gonadotropin-releasing hormone (GnRH) pulse generation. Three types of neurokinin receptors (NKRs), NK1R, NK2R and NK3R, are found in the brain. Although NKB preferentially binds to NK3R, other NKRs are possibly also involved in NKB action. The present study examined the effects of intravenous administration of the NKR subtype-selective agonists GR73632 (NK1R), GR64349 (NK2R), and senktide (NK3R) on GnRH pulse generator activity and luteinizing hormone (LH) secretion. Multiple-unit activity (MUA) was monitored in ovariectomized goats (n = 5) implanted with recording electrodes. Characteristic increases in MUA (MUA volleys) were considered GnRH pulse generator activity. Although three NKR agonists dose-dependently induced an MUA volley and an accompanying increase in LH secretion, the efficacy in inducing the volley markedly differed. As little as 10 nmol of senktide induced an MUA volley in all goats, whereas a dose of 1000 nmol was only effective for the NK1R and NK2R agonists in two and four goats, respectively. When the treatment failed to evoke an MUA volley, no apparent change was observed in the MUA or LH secretion. Similar effects of the NK2R and NK3R agonists were observed in the presence of estradiol. The results demonstrated that NK3R plays a predominant role in GnRH pulse generation and suggested that the contributions of NK1R and NK2R to this mechanism may be few, if any, in goats. PMID:25345909

  9. Neuroprotection and dopamine agonists.

    PubMed

    Schapira, Anthony H V

    2002-02-26

    Several factors are known to be capable of inducing relatively selective dopaminergic cell death in the substantia nigra and inducing the clinical features that characterize Parkinson's disease (PD). Neuronal toxins such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can induce parkinsonism in human and animal models, and rotenone, another specific mitochondrial complex I inhibitor, can induce similar effects in rodents to produce a model for PD. Studies in twins suggest a significant genetic component to young-onset PD, and several gene mutations have now been identified as causing familial autosomal dominant or autosomal recessive PD. Etiologic factors including free radical-mediated damage (including excitotoxicity), mitochondrial dysfunction, and inflammation-mediated cell damage can contribute to pathogenesis. In addition, the recent interest in protein misfolding, aggregation, and proteosomal activity has provided further insight into potential pathogenetic pathways in PD. Against this background there has been increasing interest in the development of drugs to modify these biochemical abnormalities and thus alter the course of PD, either by retarding the rate of cell death or by restoring function to neurons that are likely to be damaged but not dead. In this context, dopamine agonists have shown significant promise. Not only do these drugs provide symptomatic relief of PD but they also appear to be associated with a significant decrease in the rate of motor complications and to be capable of protecting against some of the adverse consequences of levodopa use. However, evidence is now emerging that dopamine agonists may have additional neuroprotective properties. As a group, they have antioxidant actions in vitro and in vivo. More specifically, the D(2)/D(3) dopamine agonist pramipexole may have neuroprotective activity that is, at least in part, unrelated to its dopamine agonist action. Protection in cell and animal models against a variety of toxins, including MPTP and 6-hydroxydopamine, confirms that this agonist has in vitro and in vivo neuroprotective action. Evidence is now emerging that some of this may be mediated by direct action on mitochondrial membrane potential and the inhibition of apoptosis. If the neuroprotective action of this drug is confirmed in patients with PD, this will have important implications for its early use in patients. PMID:11909981

  10. Interactions of chaperonin with a weakly active anthranilate synthase from the aphid endosymbiont Buchnera aphidicola.

    PubMed

    Huang, Chia-Ying; Lee, Chi-Ying; Wu, Hsiao-Chen; Kuo, Mei-Hwa; Lai, Chi-Yung

    2008-11-01

    The endosymbiotic bacterium Buchnera provides its aphid host with essential amino acids. Buchnera is typical of intracellular symbiotic and parasitic microorganisms in having a small effective population size, which is believed to accelerate genetic drift and reduce the stability of gene products. It is hypothesized that Buchnera mitigates protein instability with an increased production of the chaperonins GroESL. In this paper, we report the expression and functional analysis of trpE, a plasmid-borne fast-evolving gene encoding the tryptophan biosynthesis enzyme anthranilate synthase. We overcame the problem of low enzyme stability by using an anthranilate synthase-deficient mutant of E. coli as the expression host and the method of genetic complementation for detection of the enzyme activity. We showed that the Buchnera anthranilate synthase was only weakly active at the temperature of 26 degrees C but became inactive at the higher temperatures of 32 degrees C and 37 degrees C and that the coexpression with chaperonin genes groESL of E. coli enhanced the function of the Buchnera enzyme. These findings are consistent with the proposed role of groESL in the Buchnera-aphid symbiosis. PMID:18478288

  11. Pharmacological evidence of bradykinin regeneration from extended sequences that behave as peptidase–activated B2 receptor agonists

    PubMed Central

    Charest-Morin, Xavier; Roy, Caroline; Fortin, Émile-Jacques; Bouthillier, Johanne; Marceau, François

    2014-01-01

    While bradykinin (BK) is known to be degraded by angiotensin converting enzyme (ACE), we have recently discovered that Met-Lys-BK-Ser-Ser is paradoxically activated by ACE. We designed and evaluated additional “prodrug” peptides extended around the BK sequence as potential ligands that could be locally activated by vascular or blood plasma peptidases. BK regeneration was estimated using the contractility of the human umbilical vein as model of vascular functions mediated by endogenous B2 receptors (B2Rs) and the endocytosis of the fusion protein B2R-green fluorescent protein (B2R-GFP) expressed in Human Embryonic Kidney 293 cells. Of three BK sequences extended by a C-terminal dipeptide, BK-His-Leu had the most desirable profile, exhibiting little direct affinity for the receptor but a significant one for ACE (as shown by competition of [3H]BK binding to B2R-GFP or of [3H]enalaprilat to recombinant ACE, respectively). The potency of the contractile effect of this analog on the vein was reduced 18-fold by the ACE inhibitor enalaprilat, pharmacologically evidencing BK regeneration in situ. BK-Arg, a potential substrate of arginine carboxypeptidases, had a low affinity for B2Rs and its potency as a contractile agent was reduced 15-fold by tissue treatment with an inhibitor of these enzymes, Plummer’s inhibitor. B2R-GFP internalization in response to 100 nM of the extended peptides recapitulated these findings, as enalaprilat selectively inhibited the effect of BK-His-Leu and Plummer’s inhibitor, that of BK-Arg. The two peptidase inhibitors did not affect BK-induced effects in either assay. The novel C-terminally extended BKs had no or very little affinity for the kinin B1 receptor (competition of [3H]Lys-des-Arg9-BK binding). The feasibility of peptidase-activated B2R agonists is illustrated by C-terminal extensions of the BK sequence. PMID:24639651

  12. Agonist-induced changes in RalA activities allows the prediction of the endocytosis of G protein-coupled receptors.

    PubMed

    Zheng, Mei; Zhang, Xiaohan; Guo, Shuohan; Zhang, Xiaowei; Min, Chengchun; Cheon, Seung Hoon; Oak, Min-Ho; Kim, Young Ran; Kim, Kyeong-Man

    2016-01-01

    GTP binding proteins are classified into two families: heterotrimeric large G proteins which are composed of three subunits, and one subunit of small G proteins. Roles of small G proteins in the intracellular trafficking of G protein-coupled receptors (GPCRs) were studied. Among various small G proteins tested, GTP-bound form (G23V) of RalA inhibited the internalization of dopamine D2 receptor independently of the previously reported downstream effectors of RalA, such as Ral-binding protein 1 and PLD. With high affinity for GRK2, active RalA inhibited the GPCR endocytosis by sequestering the GRK2 from receptors. When it was tested for several GPCRs including an endogenous GPCR, lysophosphatidic acid receptor 1, agonist-induced conversion of GTP-bound to GDP-bound RalA, which presumably releases the sequestered GRK2, was observed selectively with the GPCRs which have tendency to undergo endocytosis. Conversion of RalA from active to inactive state occurred by translocation of RGL, a guanine nucleotide exchange factor, from the plasma membrane to cytosol as a complex with Gβγ. These results suggest that agonist-induced Gβγ-mediated conversion of RalA from the GTP-bound form to the GDP-bound form could be a mechanism to facilitate agonist-induced internalization of GPCRs. PMID:26477566

  13. NICOTINE EFFECTS ON THE MOTOR ACTIVITY OF MICE EXPOSED PRENATALLY TO THE NICOTINIC AGONIST ANATOXIN-A.

    EPA Science Inventory

    Several studies in the literature have shown that exposure of mice and rats to nicotine early in development alters its effects when the rodents are subsequently challenged with nicotine. Anatoxin-a is a nicotinic agonist produced by several genera of cyanobacteria, and has caus...

  14. A highly selective beta1-adrenergic blocker with partial beta2-agonist activity derived from ferulic acid, an active component of Ligusticum wallichii Franch.

    PubMed

    Wu, B N; Huang, Y C; Wu, H M; Hong, S J; Chiang, L C; Chen, I J

    1998-05-01

    Short-term injection of ferulinolol (0.1, 0.5, and 1.0 mg/kg, i.v.) produced dose-dependent bradycardia responses in pentobarbital-anesthetized Wistar rats, whereas it had no significant effects on the blood pressure. Ferulinolol markedly inhibited the tachycardia effects induced by (-)isoproterenol but did not show any blocking effect on the arterial pressor responses induced by (-)phenylephrine. These findings clearly suggested that ferulinolol had a beta-adrenergic blocking activity; nevertheless, it did not involve an alpha-adrenergic blocking action. In isolated guinea pig tissues, ferulinolol competitively antagonized (-)isoproterenol-induced positive inotropic and chronotropic effects of the atria and tracheal relaxation responses. The parallel shift to the right of the concentration-response curve of (-)isoproterenol suggested that ferulinolol was a beta-adrenoceptor-competitive antagonist. The apparent pA2 values for ferulinolol on right atria, left atria, and trachea were 7.62 +/- 0.05, 7.54 +/- 0.01, and 6.28 +/- 0.11, respectively. Ferulinolol was more potent on the atria than on tracheal tissues, demonstrating that it possessed beta1-adrenoceptor selectivity. The intrinsic sympathomimetic activity (ISA) of ferulinolol and propranolol were determined on isolated atria and trachea from reserpine-treated guinea pig. Propranolol caused significantly negative inotropic and chronotropic effects at > or =1 microM, whereas ferulinolol possessed fewer cardiodepressant activities than propranolol. In reserpine-treated tracheal strips, ferulinolol produced dose-dependent relaxant responses, but propranolol was without effectiveness. Preincubating the preparations with ICI 118,551 (0.1, 1.0, and 10 nM), a beta2-adrenoceptor antagonist, significantly shifted the concentration-relaxation curves of ferulinolol to a region of higher concentrations. These results implied that ferulinolol had a partial beta2-agonist activity. Further, binding characteristics of ferulinolol and various beta-adrenoceptor antagonists were evaluated in [3H]CGP-12177 binding to rat ventricular or lung membranes. The Ki values of ferulinolol, atenolol, metoprolol, and (-)propranolol were 103, 262, 123, and 0.23 nM, respectively, in ventricular membranes, and 2,412, 7,539, 2,186, and 0.72 nM, respectively, in lung membranes. In conclusion, ferulinolol was found to be a highly selective beta1-adrenoceptor antagonist with partial beta2-agonist activity but was devoid of alpha-adrenoceptor blocking action. PMID:9593075

  15. BU08073 a buprenorphine analogue with partial agonist activity at μ-receptors in vitro but long-lasting opioid antagonist activity in vivo in mice

    PubMed Central

    Khroyan, T V; Wu, J; Polgar, W E; Cami-Kobeci, G; Fotaki, N; Husbands, S M; Toll, L

    2015-01-01

    BACKGROUND AND PURPOSE Buprenorphine is a potent analgesic with high affinity at μ, δ and κ and moderate affinity at nociceptin opioid (NOP) receptors. Nevertheless, NOP receptor activation modulates the in vivo activity of buprenorphine. Structure activity studies were conducted to design buprenorphine analogues with high affinity at each of these receptors and to characterize them in in vitro and in vivo assays. EXPERIMENTAL APPROACH Compounds were tested for binding affinity and functional activity using [35S]GTPγS binding at each receptor and a whole-cell fluorescent assay at μ receptors. BU08073 was evaluated for antinociceptive agonist and antagonist activity and for its effects on anxiety in mice. KEY RESULTS BU08073 bound with high affinity to all opioid receptors. It had virtually no efficacy at δ, κ and NOP receptors, whereas at μ receptors, BU08073 has similar efficacy as buprenorphine in both functional assays. Alone, BU08073 has anxiogenic activity and produces very little antinociception. However, BU08073 blocks morphine and U50,488-mediated antinociception. This blockade was not evident at 1 h post-treatment, but is present at 6 h and remains for up to 3–6 days. CONCLUSIONS AND IMPLICATIONS These studies provide structural requirements for synthesis of ‘universal’ opioid ligands. BU08073 had high affinity for all the opioid receptors, with moderate efficacy at μ receptors and reduced efficacy at NOP receptors, a profile suggesting potential analgesic activity. However, in vivo, BU08073 had long-lasting antagonist activity, indicating that its pharmacokinetics determined both the time course of its effects and what receptor-mediated effects were observed. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24903063

  16. Propofol Modulation of α1 Glycine Receptors Does Not Require a Structural Transition at Adjacent Subunits That Is Crucial to Agonist-Induced Activation

    PubMed Central

    2013-01-01

    Pentameric glycine receptors (GlyRs) couple agonist binding to activation of an intrinsic ion channel. Substitution of the R271 residue impairs agonist-induced activation and is associated with the human disease hyperekplexia. On the basis of a homology model of the α1 GlyR, we substituted residues in the vicinity of R271 with cysteines, generating R271C, Q226C, and D284C single-mutant GlyRs and R271C/Q226C and R271C/D284C double-mutant GlyRs. We then examined the impact of interactions between these positions on receptor activation by glycine and modulation by the anesthetic propofol, as measured by electrophysiological experiments. Upon expression in Xenopus laevis oocytes, D284C-containing receptors were nonfunctional, despite biochemical evidence of successful cell surface expression. At R271C/Q226C GlyRs, glycine-activated whole-cell currents were increased 3-fold in the presence of the thiol reductant dithiothreitol, whereas the ability of propofol to enhance glycine-activated currents was not affected by dithiothreitol. Biochemical experiments showed that mutant R271C/Q226C subunits form covalently linked pentamers, showing that intersubunit disulfide cross-links are formed. These data indicate that intersubunit disulfide links in the transmembrane domain prevent a structural transition that is crucial to agonist-induced activation of GlyRs but not to modulation by the anesthetic propofol and implicate D284 in the functional integrity of GlyRs. PMID:23992940

  17. Detection and measurement of the agonistic activities of PCBs and mono-hydroxylated PCBs to the constitutive androstane receptor using a recombinant yeast assay.

    PubMed

    Kamata, Ryo; Shiraishi, Fujio; Kageyama, Shiho; Nakajima, Daisuke

    2015-10-01

    Polychlorinated biphenyls (PCBs) are thought to exert their toxicities mainly by binding to the aryl hydrocarbon receptor and by stimulating transcription of various genes, notably metabolizing enzymes including the cytochrome P450 (CYP) 1 family. However, PCBs and their metabolites could have potential to activate other nuclear receptors and subsequent events. We focused on the constitutive androstane receptor (CAR) inducing CYP2B and measured the agonistic activity of PCBs and mono-hydroxylated PCBs (OH-PCBs) to the CAR using yeast cells transduced with the human CAR and its response pathway. Twenty-nine of 34 tested PCBs and 72 of 91 OH-PCBs exhibited CAR agonistic effects. Of 41 OH-PCBs that had the same chlorination patterns as the tested PCBs, 9 had activities more than twice those of their non-hydroxylated analogs. In particular, 2',4',6'-trichlorobiphenyl-4-ol and 2,2',4',6'-tetrachlorobiphenyl-4-ol were 332- and 22-fold more potent than their analogs and were 15 times and 2.8 times, respectively, as active as a reference substance, 4-tert-octylphenol. The activities of 17 of the OH-PCBs were reduced to less than half those of their non-hydroxylated analogs. Four OH-PCBs derived from 3 active PCBs were inactive. However, a consistent relationship between hydroxyl substituent position and activity could not be discerned. Comprehensive evaluation of the toxic potential of PCBs and their hydroxylated metabolites and their concentrations in the environment are required. PMID:26231822

  18. Environmental, seasonal, and social modulations of basal activity in a weakly electric fish.

    PubMed

    Silva, Ana; Perrone, Rossana; Macadar, Omar

    2007-02-28

    The electric organ discharge (EOD) of weakly electric fish encodes information about species, sex, behavioral, and physiological states throughout the lifetime. Its central command is crucial for sensory-motor coordination, and is therefore the target of plastic mechanisms that adapt fish to environmental and social challenges. The EOD waveform of Brachyhypopomus pinnicaudatus is modulated by environmental factors and the neuroendocrine system. In this study we investigate the effects of water temperature and day-night cycle upon EOD rate in this species during the breeding and non-breeding seasons. During the non-breeding season, EOD rate is a linear function of water temperature and exhibits counterclockwise hysteresis. During breeding, a thermal resistance strategy prevents the decrease of EOD rate to cooling. A nocturnal increase of EOD basal rate independent of water temperature and locomotor activity was demonstrated in isolated non-breeding adults and in male-female dyads all year round. An additional increase of nocturnal EOD rate, probably acting as a social courtship signal, was found in breeding dyads. This additional increase of nocturnal EOD rate could not be fully explained by gonadal maturation and was modulated by social stimuli. This study provides novel data on the complex interactions between environment, reproductive cycle, social behavior, and electromotor output in an advantageous model of the vertebrate central nervous system. PMID:17178133

  19. PPARγ partial agonist GQ-16 strongly represses a subset of genes in 3T3-L1 adipocytes

    SciTech Connect

    Milton, Flora Aparecida; Cvoro, Aleksandra; Amato, Angelica A.; Sieglaff, Douglas H.; Filgueira, Carly S.; Arumanayagam, Anithachristy Sigamani; Caro Alves de Lima, Maria do; Rocha Pitta, Ivan; Assis Rocha Neves, Francisco de; Webb, Paul

    2015-08-28

    Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gamma (PPARγ) agonists that improve insulin resistance but trigger side effects such as weight gain, edema, congestive heart failure and bone loss. GQ-16 is a PPARγ partial agonist that improves glucose tolerance and insulin sensitivity in mouse models of obesity and diabetes without inducing weight gain or edema. It is not clear whether GQ-16 acts as a partial agonist at all PPARγ target genes, or whether it displays gene-selective actions. To determine how GQ-16 influences PPARγ activity on a gene by gene basis, we compared effects of rosiglitazone (Rosi) and GQ-16 in mature 3T3-L1 adipocytes using microarray and qRT-PCR. Rosi changed expression of 1156 genes in 3T3-L1, but GQ-16 only changed 89 genes. GQ-16 generally showed weak effects upon Rosi induced genes, consistent with partial agonist actions, but a subset of modestly Rosi induced and strongly repressed genes displayed disproportionately strong GQ-16 responses. PPARγ partial agonists MLR24 and SR1664 also exhibit disproportionately strong effects on transcriptional repression. We conclude that GQ-16 displays a continuum of weak partial agonist effects but efficiently represses some negatively regulated PPARγ responsive genes. Strong repressive effects could contribute to physiologic actions of GQ-16. - Highlights: • GQ-16 is an insulin sensitizing PPARγ ligand with reduced harmful side effects. • GQ-16 displays a continuum of weak partial agonist activities at PPARγ-induced genes. • GQ-16 exerts strong repressive effects at a subset of genes. • These inhibitor actions should be evaluated in models of adipose tissue inflammation.

  20. 3-Dimensional Scene Perception during Active Electrolocation in a Weakly Electric Pulse Fish

    PubMed Central

    von der Emde, Gerhard; Behr, Katharina; Bouton, Béatrice; Engelmann, Jacob; Fetz, Steffen; Folde, Caroline

    2010-01-01

    Weakly electric fish use active electrolocation for object detection and orientation in their environment even in complete darkness. The African mormyrid Gnathonemus petersii can detect object parameters, such as material, size, shape, and distance. Here, we tested whether individuals of this species can learn to identify 3-dimensional objects independently of the training conditions and independently of the object's position in space (rotation-invariance; size-constancy). Individual G. petersii were trained in a two-alternative forced-choice procedure to electrically discriminate between a 3-dimensional object (S+) and several alternative objects (S−). Fish were then tested whether they could identify the S+ among novel objects and whether single components of S+ were sufficient for recognition. Size-constancy was investigated by presenting the S+ together with a larger version at different distances. Rotation-invariance was tested by rotating S+ and/or S− in 3D. Our results show that electrolocating G. petersii could (1) recognize an object independently of the S− used during training. When only single components of a complex S+ were offered, recognition of S+ was more or less affected depending on which part was used. (2) Object-size was detected independently of object distance, i.e. fish showed size-constancy. (3) The majority of the fishes tested recognized their S+ even if it was rotated in space, i.e. these fishes showed rotation-invariance. (4) Object recognition was restricted to the near field around the fish and failed when objects were moved more than about 4 cm away from the animals. Our results indicate that even in complete darkness our G. petersii were capable of complex 3-dimensional scene perception using active electrolocation. PMID:20577635

  1. Kappa Opioid Receptor Agonist and Brain Ischemia

    PubMed Central

    Chunhua, Chen; Chunhua, Xi; Megumi, Sugita; Renyu, Liu

    2014-01-01

    Opioid receptors, especially Kappa opioid receptor (KOR) play an important role in the pathophysiological process of cerebral ischemia reperfusion injury. Previously accepted KOR agonists activity has included anti-nociception, cardiovascular, anti-pruritic, diuretic, and antitussive effects, while compelling evidence from various ischemic animal models indicate that KOR agonist have neuroprotective effects through various mechanisms. In this review, we aimed to demonstrate the property of KOR agonist and its role in global and focal cerebral ischemia. Based on current preclinical research, the KOR agonists may be useful as a neuroprotective agent. The recent discovery of salvinorin A, highly selective non-opioid KOR agonist, offers a new tool to study the role of KOR in brain HI injury and the protective effects of KOR agonist. The unique pharmacological profile of salvinorin A along with the long history of human usage provides its high candidacy as a potential alternative medication for brain HI injury. PMID:25574482

  2. Targeted Activation of Toll-Like Receptors: Conjugation of a Toll-Like Receptor 7 Agonist to a Monoclonal Antibody Maintains Antigen Binding and Specificity.

    PubMed

    Gadd, Adam J R; Greco, Francesca; Cobb, Alexander J A; Edwards, Alexander D

    2015-08-19

    Therapeutic activation of Toll-like receptors (TLR) has potential for cancer immunotherapy, for augmenting the activity of antitumor monoclonal antibodies (mAbs), and for improved vaccine adjuvants. A previous attempt to specifically target TLR agonists to dendritic cells (DC) using mAbs failed because conjugation led to nonspecific binding and mAbs lost specificity. We demonstrate here for the first time the successful conjugation of a small molecule TLR7 agonist to an antitumor mAb (the anti-hCD20 rituximab) without compromising antigen specificity. The TLR7 agonist UC-1V150 was conjugated to rituximab using two conjugation methods, and yield, molecular substitution ratio, retention of TLR7 activity, and specificity of antigen binding were compared. Both conjugation methods produced rituximab-UC-1V150 conjugates with UC-1V150: rituximab ratio ranging from 1:1 to 3:1 with drug loading quantified by UV spectroscopy and drug substitution ratio verified by MALDI TOF mass spectroscopy. The yield of purified conjugates varied with conjugation method and dropped as low as 31% using a method previously described for conjugating UC-1V150 to proteins, where a bifunctional cross-linker was first reacted with rituximab and second to the TLR7 agonist. We therefore developed a direct conjugation method by producing an amine-reactive UV active version of UC-1V150, termed NHS:UC-1V150. Direct conjugation with NHS:UC-1V150 was quick and simple and gave improved conjugate yields of 65-78%. Rituximab-UC-1V150 conjugates had the expected pro-inflammatory activity in vitro (EC50 28-53 nM) with a significantly increased activity over unconjugated UC-1V150 (EC50 547 nM). Antigen binding and specificity of the rituxuimab-UC-1V150 conjugates was retained, and after incubation with human peripheral blood leukocytes, all conjugates bound strongly only to CD20-expressing B cells while no nonspecific binding to CD20-negative cells was observed. Selective targeting of Toll-like receptor activation directly within tumors or to DC is now feasible. PMID:26133029

  3. The Novel PPAR α/γ Dual Agonist MHY 966 Modulates UVB–Induced Skin Inflammation by Inhibiting NF-κB Activity

    PubMed Central

    Park, Min Hi; Park, Ji Young; Lee, Hye Jin; Kim, Dae Hyun; Chung, Ki Wung; Park, Daeui; Jeong, Hyoung Oh; Kim, Hye Rim; Park, Chan Hum; Kim, So Ra; Chun, Pusoon; Byun, Youngjoo; Moon, Hyung Ryong; Chung, Hae Young

    2013-01-01

    Ultraviolet B (UVB; 290~320nm) irradiation-induced lipid peroxidation induces inflammatory responses that lead to skin wrinkle formation and epidermal thickening. Peroxisome proliferator-activated receptor (PPAR) α/γ dual agonists have the potential to be used as anti-wrinkle agents because they inhibit inflammatory response and lipid peroxidation. In this study, we evaluated the function of 2-bromo-4-(5-chloro-benzo[d]thiazol-2-yl) phenol (MHY 966), a novel synthetic PPAR α/γ dual agonist, and investigated its anti-inflammatory and anti-lipid peroxidation effects. The action of MHY 966 as a PPAR α/γ dual agonist was also determined in vitro by reporter gene assay. Additionally, 8-week-old melanin-possessing hairless mice 2 (HRM2) were exposed to 150 mJ/cm2 UVB every other day for 17 days and MHY 966 was simultaneously pre-treated every day for 17 days to investigate the molecular mechanisms involved. MHY 966 was found to stimulate the transcriptional activities of both PPAR α and γ. In HRM2 mice, we found that the skins of mice exposed to UVB showed significantly increased pro-inflammatory mediator levels (NF-κB, iNOS, and COX-2) and increased lipid peroxidation, whereas MHY 966 co-treatment down-regulated these effects of UVB by activating PPAR α and γ. Thus, the present study shows that MHY 966 exhibits beneficial effects on inflammatory responses and lipid peroxidation by simultaneously activating PPAR α and γ. The major finding of this study is that MHY 966 demonstrates potential as an agent against wrinkle formation associated with chronic UVB exposure. PMID:24130794

  4. Gonadotropin-releasing hormone type II (GnRH-II) agonist regulates the invasiveness of endometrial cancer cells through the GnRH-I receptor and mitogen-activated protein kinase (MAPK)-dependent activation of matrix metalloproteinase (MMP)-2

    PubMed Central

    2013-01-01

    Background More than 25% of patients diagnosed with endometrial carcinoma have an invasive primary cancer accompanied by metastases. Gonadotropin-releasing hormone (GnRH) plays an important role in reproduction. In mammals, expression of GnRH-II is higher than GnRH-I in reproductive tissues. Here, we examined the effect of a GnRH-II agonist on the motility of endometrial cancer cells and its mechanism of action in endometrial cancer therapy. Methods Immunoblotting and immunohistochemistry (IHC) were used to determine the expression of the GnRH-I receptor protein in human endometrial cancer. The activity of MMP-2 in the conditioned medium was determined by gelatin zymography. Cell motility was assessed by invasion and migration assay. GnRH-I receptor si-RNA was applied to knockdown GnRH-I receptor. Results The GnRH-I receptor was expressed in the endometrial cancer cells. The GnRH-II agonist promoted cell motility in a dose-dependent manner. The GnRH-II agonist induced the phosphorylation of ERK1/2 and JNK, and the phosphorylation was abolished by ERK1/2 inhibitor (U0126) and the JNK inhibitor (SP600125). Cell motility promoted by GnRH-II agonist was suppressed in cells that were pretreated with U0126 and SP600125. Moreover, U0126 and SP600125 abolished the GnRH-II agonist-induced activation of MMP-2. The inhibition of MMP-2 with MMP-2 inhibitor (OA-Hy) suppressed the increase in cell motility in response to the GnRH-II agonist. Enhanced cell motility mediated by GnRH-II agonist was also suppressed by the knockdown of the endogenous GnRH-I receptor using siRNA. Conclusion Our study indicates that GnRH-II agonist promoted cell motility of endometrial cancer cells through the GnRH-I receptor via the phosphorylation of ERK1/2 and JNK, and the subsequent, MAPK-dependent activation of MMP-2. Our findings represent a new concept regarding the mechanism of GnRH-II-induced cell motility in endometrial cancer cells and suggest the possibility of exploring GnRH-II as a potential therapeutic target for the treatment of human endometrial cancer. PMID:23786715

  5. Van Allen Probes observation and modeling of chorus excitation and propagation during weak geomagnetic activities

    NASA Astrophysics Data System (ADS)

    He, Yihua; Xiao, Fuliang; Zhou, Qinghua; Yang, Chang; Liu, Si; Baker, D. N.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.

    2015-08-01

    We report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst≈-45) and 14 January 2013 (Dst≈-18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8-6.3, with a lower frequency band 0.1-0.5fce and a peak spectral density ˜10-4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (˜10-300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a bi-Maxwellian distribution to model the observed electron distribution, we perform ray tracing simulations to show that nightside chorus waves are indeed produced by the observed electron distribution with a peak growth for a field-aligned propagation approximately between 0.3fce and 0.4fce, at latitude <7°. Moreover, chorus waves launched with initial normal angles either θ<90° or >90° propagate along the field either northward or southward and then bounce back either away from Earth for a lower frequency or toward Earth for higher frequencies. The current results indicate that nightside chorus waves can be excited even during weak geomagnetic activities in cases of continuous injection associated with negative Bz. Moreover, we examine a dayside event during a small storm C on 8 May 2014 (Dst≈-45) and find that the observed anisotropic energetic electron distributions potentially contribute to the generation of dayside chorus waves, but this requires more thorough studies in the future.

  6. Van Allen Probes observation and modeling of chorus excitation and propagation during weak geomagnetic activities

    DOE PAGESBeta

    He, Yihua; Xiao, Fuliang; Zhou, Qinghua; Yang, Chang; Liu, Si; Baker, D. N.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, H. E.; et al

    2015-08-20

    We report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst ≈ –45) and 14 January 2013 (Dst ≈ –18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8 – 6.3, with a lower frequency band 0.1–0.5fce and a peak spectral density ~10–4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (~10–300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a bi-Maxwellian distribution to model the observed electron distribution, we perform ray tracing simulations tomore » show that nightside chorus waves are indeed produced by the observed electron distribution with a peak growth for a field-aligned propagation approximately between 0.3fce and 0.4fce, at latitude <7°. Moreover, chorus waves launched with initial normal angles either θ < 90° or > 90° propagate along the field either northward or southward and then bounce back either away from Earth for a lower frequency or toward Earth for higher frequencies. The current results indicate that nightside chorus waves can be excited even during weak geomagnetic activities in cases of continuous injection associated with negative Bz. Furthermore, we examine a dayside event during a small storm C on 8 May 2014 (Dst ≈ –45) and find that the observed anisotropic energetic electron distributions potentially contribute to the generation of dayside chorus waves, but this requires more thorough studies in the future.« less

  7. Van Allen Probes observation and modeling of chorus excitation and propagation during weak geomagnetic activities

    SciTech Connect

    He, Yihua; Xiao, Fuliang; Zhou, Qinghua; Yang, Chang; Liu, Si; Baker, D. N.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.

    2015-08-20

    We report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst ≈ –45) and 14 January 2013 (Dst ≈ –18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8 – 6.3, with a lower frequency band 0.1–0.5fce and a peak spectral density ~10–4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (~10–300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a bi-Maxwellian distribution to model the observed electron distribution, we perform ray tracing simulations to show that nightside chorus waves are indeed produced by the observed electron distribution with a peak growth for a field-aligned propagation approximately between 0.3fce and 0.4fce, at latitude <7°. Moreover, chorus waves launched with initial normal angles either θ < 90° or > 90° propagate along the field either northward or southward and then bounce back either away from Earth for a lower frequency or toward Earth for higher frequencies. The current results indicate that nightside chorus waves can be excited even during weak geomagnetic activities in cases of continuous injection associated with negative Bz. Furthermore, we examine a dayside event during a small storm C on 8 May 2014 (Dst ≈ –45) and find that the observed anisotropic energetic electron distributions potentially contribute to the generation of dayside chorus waves, but this requires more thorough studies in the future.

  8. The adenosine A2A receptor antagonist, istradefylline enhances anti-parkinsonian activity induced by combined treatment with low doses of L-DOPA and dopamine agonists in MPTP-treated common marmosets.

    PubMed

    Uchida, Shin-ichi; Soshiroda, Kazuhiro; Okita, Eri; Kawai-Uchida, Mika; Mori, Akihisa; Jenner, Peter; Kanda, Tomoyuki

    2015-11-01

    The adenosine A2A receptor antagonist, istradefylline improves motor function in patients with advanced Parkinson's disease (PD) optimally treated with a combination of L-DOPA and a dopamine agonist without increasing the risk of troublesome dyskinesia. However, the effects of istradefylline on motor function when administered in combination with low dose of L-DOPA and dopamine agonists as occurs in early PD are unknown. We investigated whether istradefylline enhances the combined anti-parkinsonian effects of a suboptimal dose of L-DOPA and a threshold dose of either the non-ergot dopamine agonist, ropinirole or the ergot dopamine agonist, pergolide in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated common marmoset. Threshold doses of ropinirole (0.025-0.075 mg/kg p.o.) and pergolide (0.01 mg/kg p.o.) produced a weak anti-parkinsonian effect. Co-administration of a suboptimal dose of L-DOPA (2.5mg/kg p.o.) with threshold doses of the dopamine agonists enhanced their anti-parkinsonian effect that led to increased 'ON' time without dyskinesia appearing. Administering istradefylline (10mg/kg p.o.) with the threshold doses of dopamine agonists and the suboptimal dose of L-DOPA in a triple combination caused a further enhancement of the anti-parkinsonian response but dyskinesia was still absent. In early PD, dopamine agonists are often used as first-line monotherapy, but efficacy is usually lost within a few years, at which time L-DOPA is added but with the risk of dyskinesia appearance. These results show that istradefylline is effective in improving motor function in combination with low dose dopaminergic drug treatment without provoking dyskinesia. PMID:26415982

  9. Activation of developmental nuclear fibroblast growth factor receptor 1 signaling and neurogenesis in adult brain by α7 nicotinic receptor agonist.

    PubMed

    Narla, Sridhar T; Klejbor, Ilona; Birkaya, Barbara; Lee, Yu-Wei; Morys, Janusz; Stachowiak, Ewa K; Prokop, Dorota; Bencherif, Merouane; Stachowiak, Michal K

    2013-10-01

    Reactivation of endogenous neurogenesis in the adult brain or spinal cord holds the key for treatment of central nervous system injuries and neurodegenerative disorders, which are major health care issues for the world's aging population. We have previously shown that activation of developmental integrative nuclear fibroblast growth factor receptor 1 (FGFR1) signaling (INFS), via gene transfection, reactivates neurogenesis in the adult brain by promoting neuronal differentiation of brain neural stem/progenitor cells (NS/PCs). In the present study, we report that targeting the α7 nicotinic acetylcholine receptors (α7nAChRs) with a specific TC-7020 agonist led to a robust accumulation of endogenous FGFR1 in the cell nucleus. Nuclear FGFR1 accumulation was accompanied by an inhibition of proliferation of NS/PCs in the subventricular zone (SVZ) and by the generation of new neurons. Neuronal differentiation was observed in different regions of the adult mouse brain, including (a) βIII-Tubulin-expressing cortical neurons, (b) calretinin-expressing hippocampal neurons, and (c) cells in substantia nigra expressing the predopaminergic Nurr1+ phenotype. Furthermore, we showed that in vitro stimulation of neural stem/progenitor cells with α7nAChR agonist directly activated INFS and neuronal-like differentiation. TC-7020 stimulation of the βIII-Tubulin gene was accompanied by increased binding of FGFR1, CREB binding protein, and RNA polymerase II to a Nur77 targeted promoter region. TC-7020 augmented Nur77-dependent activation of nerve growth factor inducible-B protein responsive element, indicating that α7nAChR upregulation of βIII-Tubulin involves neurogenic FGFR1-Nur signaling. The reactivation of INFS and neurogenesis in adult brain by the α7nAChR agonist may offer a new strategy to treat brain injuries, neurodegenerative diseases, and neurodevelopmental diseases. PMID:24014683

  10. Activation of Developmental Nuclear Fibroblast Growth Factor Receptor 1 Signaling and Neurogenesis in Adult Brain by α7 Nicotinic Receptor Agonist

    PubMed Central

    Narla, Sridhar T.; Klejbor, Ilona; Birkaya, Barbara; Lee, Yu-Wei; Morys, Janusz; Stachowiak, Ewa K.; Prokop, Dorota; Bencherif, Merouane

    2013-01-01

    Reactivation of endogenous neurogenesis in the adult brain or spinal cord holds the key for treatment of central nervous system injuries and neurodegenerative disorders, which are major health care issues for the world's aging population. We have previously shown that activation of developmental integrative nuclear fibroblast growth factor receptor 1 (FGFR1) signaling (INFS), via gene transfection, reactivates neurogenesis in the adult brain by promoting neuronal differentiation of brain neural stem/progenitor cells (NS/PCs). In the present study, we report that targeting the α7 nicotinic acetylcholine receptors (α7nAChRs) with a specific TC-7020 agonist led to a robust accumulation of endogenous FGFR1 in the cell nucleus. Nuclear FGFR1 accumulation was accompanied by an inhibition of proliferation of NS/PCs in the subventricular zone (SVZ) and by the generation of new neurons. Neuronal differentiation was observed in different regions of the adult mouse brain, including (a) βIII-Tubulin-expressing cortical neurons, (b) calretinin-expressing hippocampal neurons, and (c) cells in substantia nigra expressing the predopaminergic Nurr1+ phenotype. Furthermore, we showed that in vitro stimulation of neural stem/progenitor cells with α7nAChR agonist directly activated INFS and neuronal-like differentiation. TC-7020 stimulation of the βIII-Tubulin gene was accompanied by increased binding of FGFR1, CREB binding protein, and RNA polymerase II to a Nur77 targeted promoter region. TC-7020 augmented Nur77-dependent activation of nerve growth factor inducible-B protein responsive element, indicating that α7nAChR upregulation of βIII-Tubulin involves neurogenic FGFR1-Nur signaling. The reactivation of INFS and neurogenesis in adult brain by the α7nAChR agonist may offer a new strategy to treat brain injuries, neurodegenerative diseases, and neurodevelopmental diseases. PMID:24014683

  11. A potential role for nuclear factor of activated T-cells in receptor tyrosine kinase and G-protein-coupled receptor agonist-induced cell proliferation.

    PubMed Central

    Yellaturu, Chandrahasa R; Ghosh, Salil K; Rao, R K; Jennings, Lisa K; Hassid, Aviv; Rao, Gadiparthi N

    2002-01-01

    We have studied the role of nuclear factor of activated T-cells (NFAT) transcription factors in the induction of vascular smooth muscle cell (VSMC) growth by platelet-derived growth factor-BB (PDGF-BB) and thrombin, the receptor tyrosine kinase (RTK) and G-protein-coupled receptor (GPCR) agonists, respectively. NFATc1 but not NFATc2 or NFATc3 was translocated from the cytoplasm to the nucleus upon treatment of VSMCs with PDGF-BB or thrombin. Translocation of NFATc1 was followed by an increase in NFAT-DNA binding activity and NFAT-dependent reporter gene expression. Cyclosporin A (CsA), a potent and specific inhibitor of calcineurin, a calcium/calmodulin-dependent serine phosphatase involved in the dephosphorylation and activation of NFATs, blocked NFAT-DNA binding activity and NFAT-dependent reporter gene expression induced by PDGF-BB and thrombin. CsA also completely inhibited PDGF-BB- and thrombin-induced VSMC growth, as measured by DNA synthesis and cell number. In addition, forced expression of the NFAT-competing peptide VIVIT for calcineurin binding significantly attenuated the DNA synthesis induced by PDGF-BB and thrombin in VSMCs. Together, these findings for the first time demonstrate a role for NFATs in RTK and GPCR agonist-induced growth in VSMCs. PMID:12188924

  12. Modulation of agonist stimulated adenylyl cyclase and GTPase activity by L-pro-L-leu-glycinamide and its peptidomimetic analogue in rat striatal membranes.

    PubMed

    Mishra, R K; Makman, M H; Costain, W J; Nair, V D; Johnson, R L

    1999-07-01

    L-prolyl-L-leucyl-glycinamide (PLG), also known as melanocyte-stimulating hormone release inhibiting factor (MIF-1), is an endogenous brain tripeptide. Previous studies have shown that PLG, and its peptidomimetic analogues, render dopamine D2 receptors more responsive to agonists by maintaining the high-affinity binding state of the receptors. In the present study, we examined the effect PLG and its analogue 3(R)-[(2(S)-pyrrolidylcarbonyl)amino]-2-oxo-1-pyrrolidineacetam ide (PAOPA) on dopamine-stimulated adenylyl cyclase and NPA-stimulated GTPase activity in rat striatal membranes. Dopamine-stimulated adenylyl cyclase activity was inhibited by both PLG and PAOPA in a dose-dependent manner, whereas R(-)-propylnorapomorphine (NPA)-stimulated low Km GTPase activity was significantly increased by 1 microM PLG or 1 nM PAOPA. These results suggest that PLG and PAOPA maintain the high affinity state of the D2 receptor by increasing GTP hydrolysis through stimulation of agonist-induced GTPase activity. PMID:10821635

  13. The selective mGlu2/3 receptor agonist LY354740 attenuates morphine-withdrawal-induced activation of locus coeruleus neurons and behavioral signs of morphine withdrawal.

    PubMed

    Vandergriff, J; Rasmussen, K

    1999-02-01

    Naltrexone-precipitated morphine withdrawal induces hyperactivity of locus coeruleus (LC) neurons, as well as a plethora of behavioral withdrawal signs. Previous research has demonstrated that an increased release of glutamate and activation of AMPA receptors, particularly in the LC, play an important role in opiate withdrawal. LY354740 is a novel Group II metabotropic glutamate mGlu2/3 receptor agonist that decreases the release of glutamate. Therefore, we investigated the effect of LY354740 on naltrexone-precipitated morphine-withdrawal-induced activation of LC neurons and behavioral signs of morphine withdrawal. In in vivo recordings from anesthetized rats, pretreatment with LY354740 (3-30 mg/kg, s.c.) dose-dependently attenuated the morphine-withdrawal-induced activation of LC neurons. In unanesthetized, morphine-dependent animals, pretreatment with LY354740 (3-30 mg/kg, s.c.) dose-dependently suppressed the severity and occurrence of many naltrexone-precipitated morphine-withdrawal signs. These results indicate mGlu2/3 receptor agonists: (1) can attenuate the morphine-withdrawal-induced activation of LC neurons and many behavioral signs of morphine withdrawal; and (2) may have therapeutic effects in man for the treatment of opiate withdrawal. PMID:10218862

  14. An Orally Active Phenylaminotetralin-Chemotype Serotonin 5-HT7 and 5-HT1A Receptor Partial Agonist that Corrects Motor Stereotypy in Mouse Models.

    PubMed

    Canal, Clinton E; Felsing, Daniel E; Liu, Yue; Zhu, Wanying; Wood, JodiAnne T; Perry, Charles K; Vemula, Rajender; Booth, Raymond G

    2015-07-15

    Stereotypy (e.g., repetitive hand waving) is a key phenotype of autism spectrum disorder, Fragile X and Rett syndromes, and other neuropsychiatric disorders, and its severity correlates with cognitive and attention deficits. There are no effective treatments, however, for stereotypy. Perturbation of serotonin (5-HT) neurotransmission contributes to stereotypy, suggesting that distinct 5-HT receptors may be pharmacotherapeutic targets to treat stereotypy and related neuropsychiatric symptoms. For example, preclinical studies indicate that 5-HT7 receptor activation corrects deficits in mouse models of Fragile X and Rett syndromes, and clinical trials for autism are underway with buspirone, a 5-HT1A partial agonist with relevant affinity at 5-HT7 receptors. Herein, we report the synthesis, in vitro molecular pharmacology, behavioral pharmacology, and pharmacokinetic parameters in mice after subcutaneous and oral administration of (+)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine ((+)-5-FPT), a new, dual partial agonist targeting both 5-HT7 (Ki = 5.8 nM, EC50 = 34 nM) and 5-HT1A (Ki = 22 nM, EC50 = 40 nM) receptors. Three unique, heterogeneous mouse models were used to assess the efficacy of (+)-5-FPT to reduce stereotypy: idiopathic jumping in C58/J mice, repetitive body rotations in C57BL/6J mice treated with the NMDA antagonist, MK-801, and repetitive head twitching in C57BL/6J mice treated with the 5-HT2 agonist, DOI. Systemic (+)-5-FPT potently and efficaciously reduced or eliminated stereotypy in each of the mouse models without altering locomotor behavior on its own, and additional tests showed that (+)-5-FPT, at the highest behaviorally active dose tested, enhanced social interaction and did not cause behaviors indicative of serotonin syndrome. These data suggest that (+)-5-FPT is a promising medication for treating stereotypy in psychiatric disorders. PMID:26011730

  15. Prostacyclin agonists reduce early atherosclerosis in hyperlipidemic hamsters. Octimibate and BMY 42393 suppress monocyte chemotaxis, macrophage cholesteryl ester accumulation, scavenger receptor activity, and tumor necrosis factor production.

    PubMed

    Kowala, M C; Mazzucco, C E; Hartl, K S; Seiler, S M; Warr, G A; Abid, S; Grove, R I

    1993-03-01

    We determined the effects of two prostacyclin agonists (octimibate and BMY 42393) on the progression of the fatty streak in vivo and on macrophage function in vitro. Hamsters were fed chow plus 0.05% cholesterol and 10% coconut oil. Control hamsters were compared with animals receiving either octimibate (10 or 30 mg/kg per day) or BMY 42393 (30 mg/kg per day). After 10 weeks of treatment, octimibate decreased plasma total cholesterol and triglycerides by 43% and 32%, respectively. Neither agonist affected blood pressure or heart rate. Lesion-prone aortic arches were stained with hematoxylin and oil red O and examined en face. Compared with controls, octimibate and BMY 42393 on average decreased mononuclear cells attached to the luminal surface by 44% and reduced subendothelial macrophage-foam cell number by 56%, foam cell size by 38%, and fatty streak area by 63%. Since octimibate is a putative inhibitor of acyl coenzyme A cholesterol acyltransferase, we studied the effect of both agents on cholesteryl ester metabolism in murine macrophages. At 10 microM, octimibate and BMY 42393 decreased cholesteryl ester accumulation in macrophages by 90% and 41%, respectively. Octimibate inhibited cholesteryl ester synthesis by 96% and increased the rate of cholesteryl ester degradation by 52%. Both prostacyclin agonists reduced macrophage scavenger receptor-mediated uptake of acetylated low density lipoprotein by 24-66% and increased cyclic adenosine monophosphate levels. Octimibate and BMY 42393 inhibited the secretion of tumor necrosis factor by 80-88% when macrophages were activated with lipopolysaccharide. At 10 microM, both agents decreased human monocyte chemotaxis to N-formyl-methionyl-leucyl-phenylalanine by 64-79%. The in vitro results with octimibate and BMY 42393 are consistent with the low number of small foam cells quantified in vivo. We suggest that octimibate and BMY 42393 suppress monocyte-macrophage atherogenic activity and cytokine production and thus inhibit the development of early atherosclerosis. PMID:8443148

  16. Bronchodilator activity of a new inhaled beta 2-adrenoceptor agonist, tulobuterol and its protective effect in exercise-induced asthma.

    PubMed Central

    Patel, K R

    1986-01-01

    In fifteen patients with asthma tulobuterol, a new beta 2-adrenoceptor agonist, given by inhalation in 100 micrograms increments up to a cumulative dose of 600 micrograms produced dose related increases in both the FEV1 and FVC. The bronchodilation was observed within 5 min of the first dose. In a further nine patients tulobuterol 200 micrograms and 400 micrograms aerosol inhibited exercise-induced asthma following 6-8 min treadmill exercise and the effect was comparable to 200 micrograms salbutamol aerosol. Minor muscle tremors were observed in two patients with 400 micrograms of tulobuterol but no significant changes in pulse rate or blood pressure were noted. PMID:3513811

  17. Modulation of Female Genital Tract-Derived Dendritic Cell Migration and Activation in Response to Inflammatory Cytokines and Toll-Like Receptor Agonists

    PubMed Central

    Shey, Muki S.; Maharaj, Niren; Archary, Derseree; Ngcapu, Sinaye; Garrett, Nigel; Abdool Karim, Salim; Passmore, Jo-Ann S.

    2016-01-01

    HIV transmission across the genital mucosa is a major mode of new HIV infections in women. The probability of infection may be influenced by several factors including recruitment and activation of HIV target cells, such as dendritic cells (DCs) and cytokine production, associated with genital inflammation. We evaluated the role of inflammatory cytokines and TLR signaling in migration and activation of genital tract DCs in the human cervical explant model. Hysterectomy tissues from 10 HIV-negative and 7 HIV-positive donor women were separated into ecto- and endocervical explants, and incubated with inflammatory cytokines (TNF-α, IL-1β, IL-8, MIP-1β) or agonists for TLR4 (LPS), TLR2/1 (PAM3) and TLR7/8 (R848). Migration (frequency) and activation (HLA-DR expression) of myeloid and plasmacytoid DCs and Langerhans cells were measured by flow cytometry. We observed that cytokines, LPS and PAM3 induced activation of migrating myeloid and plasmacytoid DCs. LPS induced a 3.6 fold lower levels of migration of plasmacytoid DCs from HIV-infected women compared with HIV-uninfected women (median activation indices of 2.932 vs 0.833). There was however a 4.5 fold increase in migration of Langerhans cells in HIV-infected compared with HIV-uninfected women in response to cytokines (median activation indices of 3.539 vs 0.77). Only TLR agonists induced migration and activation of DCs from endocervical explants. Hormonal contraception use was associated with an increase in activation of DC subsets in the endo and ectocervical explants. We conclude that inflammatory signals in the female genital tract induced DC migration and activation, with possible important implications for HIV susceptibility of cervical tissues. PMID:27171482

  18. Peroxisome proliferator-activated receptor-γ (PPARγ) agonist is neuroprotective and stimulates PGC-1α expression and CREB phosphorylation in human dopaminergic neurons.

    PubMed

    Mäkelä, Johanna; Tselykh, Timofey V; Kukkonen, Jyrki P; Eriksson, Ove; Korhonen, Laura T; Lindholm, Dan

    2016-03-01

    Mitochondrial dysfunction has been linked to several neurodegenerative diseases such as Parkinson's disease (PD). Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master gene for mitochondrial biogenesis and has been shown to be neuroprotective in models of PD. In this work we have studied the mechanisms by which peroxisome proliferator-activated receptor-γ (PPARγ) selective agonist N-(2-benzoylphenyl)-O-[2-(methyl-2-pyridinylamino)ethyl]-l-tyrosine hydrate (GW1929) acts on human dopaminergic neurons in culture. Data showed that GW1929 increased the viability of human dopaminergic neurons and protected them against oxidative stress induced by H2O2 and the mitochondrial toxin Rotenone. The enhanced resilience of the neurons was attributed to increased levels of mitochondrial antioxidants and of PGC-1α. GW1929 treatment further increased cell respiration, mitochondrial biogenesis and sirtuin-1 (SIRT1) expression in the human dopaminergic neurons. Phosphorylation of cAMP responsive element-binding protein (CREB) was also robustly increased in GW1929-treated cells. Together these results show that the PPARγ agonist GW1929 influences CREB signaling and PGC-1α activities in the human dopaminergic neurons contributing to an increased cell viability. This supports the view that drugs acting on the PPARγ-PGC-1α signaling in neurons may have beneficial effects in PD and possible also in other brain disorders. PMID:26631533

  19. Rat white adipocytes activate p85/p110 PI3K and induce PM GLUT4 in response to adrenoceptor agonists or aluminum fluoride.

    PubMed

    Ohsaka, Y; Nomura, Y

    2016-03-01

    Adipocyte responses to adrenergic and ß-adrenoceptor(-AR) (adrenoceptor) regulation are not sufficiently understood, and information helpful for elucidating the adrenoceptor-responsive machinery is insufficient. Here we show by using immunoprecipitated kinase analysis with a phosphatidylinositol 3-kinase (PI3K) p85 antibody that PI3K activation was induced by treatment with 10 or 100 µM norepinephrine (NE) for 15 min or with 10 mM aluminum fluoride (AF, a guanosine triphosphate (GTP)-binding (G) protein activator) for 20 min in white adipocytes (rat epididymal adipocytes) and that treatment with pertussis toxin (PTX, a G-protein inactivator) inhibited PI3K activation induced by the 20-min treatment with AF in the cells. In addition, western blot analysis revealed that glucose transporter 4 (GLUT4) level in the adipocyte plasma membrane (PM) fraction was increased by treatment with 10 µM NE, 100 µM dobutamine (DOB, a ß1-AR agonist), or 0.1 µM CL316243 (CL, a ß3-AR agonist) for 30 min or with 10 mM AF for 20 min. NE or AF treatment triggered 2-deoxyglucose (2-DG) uptake into adipocytes under the above conditions. Our results advance the understanding of responses to adrenoceptor regulation in white adipocytes and provide possible clues for clarifying the machinery involved in adrenergic and ß-AR responses in the cells. PMID:27030626

  20. Coordinated Activation of Toll-Like Receptor8 (TLR8) and NLRP3 by the TLR8 Agonist, VTX-2337, Ignites Tumoricidal Natural Killer Cell Activity

    PubMed Central

    Dietsch, Gregory N.; Lu, Hailing; Yang, Yi; Morishima, Chihiro; Chow, Laura Q.; Disis, Mary L.; Hershberg, Robert M.

    2016-01-01

    VTX-2337 (USAN: motolimod) is a selective toll-like receptor 8 (TLR8) agonist, which is in clinical development as an immunotherapy for multiple oncology indications, including squamous cell carcinoma of the head and neck (SCCHN). Activation of TLR8 enhances natural killer cell activation, increases antibody-dependent cell-mediated cytotoxicity, and induces Th1 polarizing cytokines. Here, we show that VTX-2337 stimulates the release of mature IL-1β and IL-18 from monocytic cells through coordinated actions on both TLR8 and the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome complex. In vitro, VTX-2337 primed monocytic cells to produce pro-IL-1β, pro-IL-18, and caspase-1, and also activated the NLRP3 inflammasome, thereby mediating the release of mature IL-1β family cytokines. Inhibition of caspase-1 blocked VTX-2337-mediated NLRP3 inflammasome activation, but had little impact on production of other TLR8-induced mediators such as TNFα. IL-18 activated natural killer cells and complemented other stimulatory pathways, including FcγRIII and NKG2D, resulting in IFNγ production and expression of CD107a. NLRP3 activation in vivo was confirmed by a dose-related increase in plasma IL-1β and IL-18 levels in cynomolgus monkeys administered VTX-2337. These results are highly relevant to clinical studies of combination VTX-2337/cetuximab treatment. Cetuximab, a clinically approved, epidermal growth factor receptor-specific monoclonal antibody, activates NK cells through interactions with FcγRIII and facilitates ADCC of tumor cells. Our preliminary findings from a Phase I open-label, dose-escalation, trial that enrolled 13 patients with recurrent or metastatic SCCHN show that patient NK cells become more responsive to stimulation by NKG2D or FcγRIII following VTX-2337 treatment. Together, these results indicate that TLR8 stimulation and inflammasome activation by VTX-2337 can complement FcγRIII engagement and may augment clinical responses in SCCHN patients treated with cetuximab. Trial Registration: ClinicalTrials.gov NCT01334177 PMID:26928328

  1. The Antidepressant Amitriptyline is a TrkA and TrkB Receptor Agonist that Promotes TrkA/TrkB Heterodimerization and Has Potent Neurotrophic Activity

    PubMed Central

    Jang, Sung-Wuk; Liu, Xia; Chan, Chi-Bun; Weinshenker, David; Hall, Randy A.; Xiao, Ge; Ye, Keqiang

    2009-01-01

    Neurotrophins, the cognate ligands for the Trk receptors, are homodimers and induce Trk dimerization through a symmetric bivalent mechanism. We report here that amitriptyline, an antidepressant drug, directly binds TrkA and TrkB and triggers their dimerization and activation. Amitriptyline, but not any other tricyclic or SSRI antidepressants, promotes TrkA autophosphorylation in primary neurons and induces neurite outgrowth in PC12 cells. Amitriptyline binds the extracellular domain of both TrkA and TrkB and promotes TrkA-TrkB receptor heterodimerization. Truncation of amitriptyline binding motif on TrkA abrogates the receptor dimerization by amitriptyline. Administration of amitriptyline to mice activates both receptors and significantly reduces kainic acid-triggered neuronal cell death. Inhibition of TrkA, but not TrkB, abolishes amitriptyline's neuroprotective effect without impairing its antidepressant activity. Thus, amitriptyline acts as a TrkA and TrkB agonist, and possesses marked neurotrophic activity. PMID:19549602

  2. Purine Receptors: GPCR Structure and Agonist Design

    PubMed Central

    Jacobson, Kenneth A.; Kim, Soo-Kyung; Costanzi, Stefano; Gao, Zhan-Guo

    2012-01-01

    An integrated approach to the study of drug-receptor interactions has been applied to adenosine receptors (ARs) and P2Y nucleotide receptors. This approach includes probing the receptor structure through site-directed mutagenesis and molecular modeling, in concert with altering the structure of the agonist ligands. Goals of this structural approach are to generate a testable hypothesis for location of the binding site and subsequently to enable the rational design of new agonists and antagonists. In this manner, receptor subtype selectivity has been increased, and agonists have been converted into partial agonists and antagonists. An approach to receptor engineering (neoceptors) has been explored, in which synthetic small molecule agonists (neoligands) are specifically tailored to activate only receptors in which the putative binding sites have been modified. This orthogonal approach to receptor activation, intended for eventual gene therapy, has been demonstrated for A3 and A2A ARs. PMID:15616163

  3. Peroxisome proliferator-activated receptor-γ agonist inhibits the mammalian target of rapamycin signaling pathway and has a protective effect in a rat model of status epilepticus

    PubMed Central

    SAN, YONG-ZHI; LIU, YU; ZHANG, YU; SHI, PING-PING; ZHU, YU-LAN

    2015-01-01

    Peroxisome proliferator-activated receptor γ (PPAR-γ) has a protective role in several neurological diseases. The present study investigated the effect of the PPAR-γ agonist, pioglitazone, on the mammalian target of rapamycin (mTOR) signaling pathway in a rat model of pentylenetetrazol (PTZ)-induced status epilepticus (SE). The investigation proceeded in two stages. First, the course of activation of the mTOR signaling pathway in PTZ-induced SE was examined to determine the time-point of peak activity, as reflected by phopshorylated (p)-mTOR/mTOR and p-S6/S6 ratios. Subsequently, pioglitazone was administrated intragastrically to investigate its effect on the mTOR signaling pathway, through western blot and immunochemical analyses. The levels of the interleukin (IL)-1β and IL-6 inflammatory cytokines were detected using ELISA, and neuronal loss was observed via Nissl staining. In the first stage of experimentation, the mTOR signaling pathway was activated, and the p-mTOR/mTOR and p-S6/S6 ratios peaked on the third day. Compared with the vehicle treated-SE group, pretreatment with pioglitazone was associated with the loss of fewer neurons, lower levels of IL-1β and IL-6, and inhibition of the activation of the mTOR signaling pathway. Therefore, the mTOR signaling pathway was activated in the PTZ-induced SE rat model, and the PPAR-γ agonist, pioglitazone, had a neuroprotective effect, by inhibiting activation of the mTOR pathway and preventing the increase in the levels of IL-1β and IL-6. PMID:25891824

  4. Effects of vision-restricting "polypeepers" on the behaviour of laying hens during adaptation, feeding, on general activity, agonistic behaviour and pecking damage.

    PubMed

    Arbi, A; Cumming, R B; Wodzicka-Tomaszewska, M

    1983-07-01

    Vision-restricting "polypeepers" have been reported to result in higher egg production with improved food utilisation in hens. In the present experiments behavioural explanations of these effects were sought. For detailed observations 128 White Leghorn X Black Australorp hens were used and for pecking damage comparisons a further 192 hens. Half were fitted with polypeepers. Birds were studied in individual cages, three-bird cages or deep litter pens by direct observation and cine-camera. Adjustment problems in feeding, stereotypic head shaking and protracted displacement neck preening occurred initially after fitting of polypeepers. Disappearance of these phenomena after about one month, however, indicated adaptation. The initial reduction of egg production associated with polypeepers, observed by others, coincided with the period of adaptation. Polypeepers resulted in less activity; birds in multiple cages and litter pens resting more, while in single cages body movement was reduced. Polypeepers caused faster eating and less wastage of both pellets and mash. In general, agonistic acts were greatly reduced in multiple cages, resulting in reduced feeding competition. Polypeepers reduced significantly the incidence of feather pecking, resulting in considerably less feather loss after three months, and more so after 14 months in lay. Over the study as a whole the reductions in activity, food spillage, agonistic behaviour and feather damage probably contribute to the lower food consumption and improved laying efficiency previously reported. PMID:6684495

  5. Comparative analyses of downstream signal transduction targets modulated after activation of the AT1 receptor by two β-arrestin-biased agonists.

    PubMed

    Santos, Geisa A; Duarte, Diego A; Parreiras-E-Silva, Lucas T; Teixeira, Felipe R; Silva-Rocha, Rafael; Oliveira, Eduardo B; Bouvier, Michel; Costa-Neto, Claudio M

    2015-01-01

    G protein-coupled receptors (GPCRs) are involved in essentially all physiological processes in mammals. The classical GPCR signal transduction mechanism occurs by coupling to G protein, but it has recently been demonstrated that interaction with β-arrestins leads to activation of pathways that are independent of the G protein pathway. Also, it has been reported that some ligands can preferentially activate one of these signaling pathways; being therefore called biased agonists for G protein or β-arrestin pathways. The angiotensin II (AngII) AT1 receptor is a prototype GPCR in the study of biased agonism due to the existence of well-known β-arrestin-biased agonists, such as [Sar(1), Ile(4), Ile(8)]-AngII (SII), and [Sar(1), D-Ala(8)]-AngII (TRV027). The aim of this study was to comparatively analyze the two above mentioned β-arrestin-biased agonists on downstream phosphorylation events and gene expression profiles. Our data reveal that activation of AT1 receptor by each ligand led to a diversity of activation profiles that is far broader than that expected from a simple dichotomy between "G protein-dependent" and "β-arrestin-dependent" signaling. We observed clusters of activation profiles common to AngII, SII, and TRV027, as well as downstream effector activation that are unique to AngII, SII, or TRV027. Analyses of β-arrestin conformational changes after AT1 receptor stimulation with SII or TRV027 suggests that the observed differences could account, at least partially, for the diversity of modulated targets observed. Our data reveal that, although the categorization "G protein-dependent" vs. "β-arrestin-dependent" signaling can be of pharmacological relevance, broader analyses of signaling pathways and downstream targets are necessary to generate an accurate activation profile for a given ligand. This may bring relevant information for drug development, as it may allow more refined comparison of drugs with similar mechanism of action and effects, but with distinct side effects. PMID:26191004

  6. Comparative analyses of downstream signal transduction targets modulated after activation of the AT1 receptor by two β-arrestin-biased agonists

    PubMed Central

    Santos, Geisa A.; Duarte, Diego A.; Parreiras-e-Silva, Lucas T.; Teixeira, Felipe R.; Silva-Rocha, Rafael; Oliveira, Eduardo B.; Bouvier, Michel; Costa-Neto, Claudio M.

    2015-01-01

    G protein-coupled receptors (GPCRs) are involved in essentially all physiological processes in mammals. The classical GPCR signal transduction mechanism occurs by coupling to G protein, but it has recently been demonstrated that interaction with β-arrestins leads to activation of pathways that are independent of the G protein pathway. Also, it has been reported that some ligands can preferentially activate one of these signaling pathways; being therefore called biased agonists for G protein or β-arrestin pathways. The angiotensin II (AngII) AT1 receptor is a prototype GPCR in the study of biased agonism due to the existence of well-known β-arrestin-biased agonists, such as [Sar1, Ile4, Ile8]-AngII (SII), and [Sar1, D-Ala8]-AngII (TRV027). The aim of this study was to comparatively analyze the two above mentioned β-arrestin-biased agonists on downstream phosphorylation events and gene expression profiles. Our data reveal that activation of AT1 receptor by each ligand led to a diversity of activation profiles that is far broader than that expected from a simple dichotomy between “G protein-dependent” and “β-arrestin-dependent” signaling. We observed clusters of activation profiles common to AngII, SII, and TRV027, as well as downstream effector activation that are unique to AngII, SII, or TRV027. Analyses of β-arrestin conformational changes after AT1 receptor stimulation with SII or TRV027 suggests that the observed differences could account, at least partially, for the diversity of modulated targets observed. Our data reveal that, although the categorization “G protein-dependent” vs. “β-arrestin-dependent” signaling can be of pharmacological relevance, broader analyses of signaling pathways and downstream targets are necessary to generate an accurate activation profile for a given ligand. This may bring relevant information for drug development, as it may allow more refined comparison of drugs with similar mechanism of action and effects, but with distinct side effects. PMID:26191004

  7. The novel antipsychotic aripiprazole is a partial agonist at short and long isoforms of D2 receptors linked to the regulation of adenylyl cyclase activity and prolactin release.

    PubMed

    Aihara, Koutoku; Shimada, Jun; Miwa, Takashi; Tottori, Katsura; Burris, Kevin D; Yocca, Frank D; Horie, Masato; Kikuchi, Tetsuro

    2004-04-01

    Aripiprazole is a novel antipsychotic with a unique mechanism of action, which differs from currently marketed typical and atypical antipsychotics. Aripiprazole has been shown to be a partial agonist at the D(2) family of dopamine (DA) receptors in biochemical and pharmacological studies. To demonstrate aripiprazole's action as a partial D(2) agonist in pituitary cells at the molecular level, we retrovirally transduced the short (D(2S)) and the long (D(2L)) form of the human DA D(2) receptor gene into a rat pituitary cell line, GH4C1. [(3)H]-raclopride saturation binding analyses revealed a B(max) value approximately four-fold higher at D(2S) receptor-expressing GH4C1 cells than at D(2L) receptor-expressing GH4C1 cells, while a K(d) value was similar. Aripiprazole inhibited forskolin-stimulated release of prolactin in both D(2S) and D(2L) receptor-expressing GH4C1 cells, whereas the maximal inhibition of prolactin release was less than that of DA. Similarly, aripiprazole partially inhibited forskolin-induced cAMP accumulation in both D(2) receptor-expressing cells. Aripiprazole antagonized the suppression attained by DA (10(-7) M) in both D(2) receptor-expressing cells and, at the maximal blockade of cAMP, yielded residual cAMP levels equal to those produced by aripiprazole alone. These results indicate that aripiprazole acts as a partial agonist at both D(2S) and D(2L) receptors expressed in GH4C1 cells. These data may explain, at least in part, the observations that aripiprazole shows a novel antipsychotic activity with minimal potential for adverse events including no significant increase of serum prolactin levels in clinical studies. PMID:15019558

  8. Activation of GPR119 by fatty acid agonists augments insulin release from clonal β-cells and isolated pancreatic islets and improves glucose tolerance in mice.

    PubMed

    Moran, Brian M; Abdel-Wahab, Yasser H A; Flatt, Peter R; McKillop, Aine M

    2014-04-01

    G-protein coupled receptor 119 (GPR119) is emerging as a potential target for the treatment of type 2 diabetes with beneficial effects on glucose homeostasis. This study assessed the insulin-secreting properties of various GPR119 agonists and the distribution of GPR119 in pancreatic islets. Endogenous ligands [oleoylethanolamide (OEA), palmitoylethanolamine (PEA)] and chemically synthetic analogues (AS-1269574, PSN-375963) were investigated in clonal BRIN-BD11 cells and mouse pancreatic islets. Secondary messenger assays such as intracellular Ca²⁺ and cAMP in response to agonists at normoglycaemic and hyperglycaemic conditions were assessed. Cytotoxicity was assessed by LDH release. AS-1269574 was the most potent and selective agonist tested in isolated islets, with an EC₅₀ value of 9.7×10⁻⁷ mol/l, enhancing insulin release maximally by 63.2%. Stimulation was also observed with GPR119 ligands; OEA (3.0×10⁻⁶ mol/l; 37.5%), PSN-375963 (2.4×10⁻⁶ mol/l; 28.7%) and PEA (1.2×10⁻⁶ mol/l; 22.2%). Results were corroborated by studies using BRIN-BD11 cells, which revealed augmentation of intracellular Ca²⁺ and cAMP. Both OEA and AS-1269574 enhanced insulin release and improved glucose tolerance in vivo in NIH Swiss mice. These results demonstrate the cellular localisation of GPR119 on islet cells (β and pancreatic polypeptide cells), its activation of the β-cell stimulus-secretion coupling pathway and glucose lowering effects in vivo. PMID:24323890

  9. Soluble epoxide hydrolase inhibition and peroxisome proliferator activated receptor γ agonist improve vascular function and decrease renal injury in hypertensive obese rats.

    PubMed

    Imig, John D; Walsh, Katie A; Hye Khan, Md Abdul; Nagasawa, Tasuku; Cherian-Shaw, Mary; Shaw, Sean M; Hammock, Bruce D

    2012-12-01

    Cardiometabolic syndrome occurs with obesity and consists of pathophysiological factors that increase the risk for cardiovascular events. Soluble epoxide hydrolase inhibition (sEHi) is a novel therapeutic approach that exerts renal and cardiovascular protection. Although sEHi as a therapeutic approach is promising, it could be more effective for the treatment of cardiometabolic syndrome when combined with peroxisome proliferator activated receptor γ (PPARγ) agonists. We hypothesized that the PPARγ agonist, rosiglitazone in combination with a sEHi (tAUCB) will provide synergistic actions to decrease blood pressure, improve vascular function, decrease inflammation, and prevent renal damage in spontaneously hypertensive obese rats (SHROB). SHROB were treated with rosiglitazone, tAUCB or the combination of tAUCB and rosiglitazone for four-weeks and compared with spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Blood pressure increased in SHROB (164 ± 7 mmHg) and decreased 10 mmHg when treated with rosiglitazone, tAUCB, or tAUCB and rosiglitazone. Mesenteric artery dilation to the K(ATP) channel opener pinacidil was attenuated in SHROB (E(Max) = 77 ± 7%), compared with WKY (E(Max) = 115 ± 19) and SHR (E(Max) = 93 ± 12%). Vasodilation to pinacidil was improved by rosiglitazone (E(Max) = 92 ± 14%) but not tAUCB. Renal macrophage infiltration increased in SHROB and significantly decreased with rosiglitazone or tAUCB and rosiglitazone treatment. Albuminuria was increased in SHROB (90 ± 20 mg/d) and was significantly decreased by the combination of tAUCB and rosiglitazone (37 ± 9 mg/d). Glomerular injury in SHROB was also significantly decreased by tAUCB and rosiglitazone. These results indicate that even though sEHi or PPARγ agonist have benefits when used individually, the combination is more beneficial for the multidisease features in cardiometabolic syndrome. PMID:23354399

  10. "Inverse" Frustrated Lewis Pairs - Activation of Dihydrogen with Organosuperbases and Moderate to Weak Lewis Acids.

    PubMed

    Mummadi, Suresh; Unruh, Daniel K; Zhao, Jiyang; Li, Shuhua; Krempner, Clemens

    2016-03-16

    A new approach to intermolecular frustrated Lewis pairs (FLPs) that combines readily available bulky organosuperbases with moderate to weak boron-containing Lewis acids is reported. These so-called "inverse" FLPs are demonstrated to heterolytically cleave dihydrogen, allowing for the isolation and structural characterization of various phosphonium borohydride salts; two FLPs proved to be efficient catalyst's in the metal-free hydrogenation of N-benzylidenaniline. PMID:26899711

  11. Discovery of Novel Multifunctional Ligands with μ/δ Opioid Agonist/Neurokinin-1 (NK1) Antagonist Activities for the Treatment of Pain.

    PubMed

    Giri, Aswini Kumar; Apostol, Christopher R; Wang, Yue; Forte, Brittany L; Largent-Milnes, Tally M; Davis, Peg; Rankin, David; Molnar, Gabriella; Olson, Keith M; Porreca, Frank; Vanderah, Todd W; Hruby, Victor J

    2015-11-12

    Multifunctional ligands with agonist bioactivities at μ/δ opioid receptors (MOR/DOR) and antagonist bioactivity at the neurokinin-1 receptor (NK1R) have been designed and synthesized. These peptide-based ligands are anticipated to produce better biological profiles (e.g., higher analgesic effect with significantly less adverse side effects) compared to those of existing drugs and to deliver better synergistic effects than coadministration of a mixture of multiple drugs. A systematic structure-activity relationship (SAR) study has been conducted to find multifunctional ligands with desired activities at three receptors. It has been found that introduction of Dmt (2,6-dimethyl-tyrosine) at the first position and NMePhe at the fourth position (ligand 3: H-Dmt-d-Ala-Gly-NMePhe-Pro-Leu-Trp-NH-Bn(3',5'-(CF3)2)) displays binding as well as functional selectivity for MOR over DOR while maintaining efficacy, potency, and antagonist activity at the NK1R. Dmt at the first position with Phe(4-F) at the fourth position (ligand 5: H-Dmt-d-Ala-Gly-Phe(4-F)-Pro-Leu-Trp-NH-Bn(3',5'-(CF3)2)) exhibits balanced binding affinities at MOR and DOR though it has higher agonist activity at DOR over MOR. This study has led to the discovery of several novel ligands including 3 and 5 with excellent in vitro biological activity profiles. Metabolic stability studies in rat plasma with ligands 3, 5, and 7 (H-Tyr-d-Ala-Gly-Phe(4-F)-Pro-Leu-Trp-NH-Bn(3',5'-(CF3)2)) showed that their stability depends on modifications at the first and fourth positions (3: T1/2 > 24 h; 5: T1/2 ≈ 6 h; 7: T1/2 > 2 h). Preliminary in vivo studies with these two ligands have shown promising antinociceptive activity. PMID:26465170

  12. Down-regulated Peroxisome Proliferator-activated Receptor ? (PPAR?) in Lung Epithelial Cells Promotes a PPAR? Agonist-reversible Proinflammatory Phenotype in Chronic Obstructive Pulmonary Disease (COPD)*

    PubMed Central

    Lakshmi, Sowmya P.; Reddy, Aravind T.; Zhang, Yingze; Sciurba, Frank C.; Mallampalli, Rama K.; Duncan, Steven R.; Reddy, Raju C.

    2014-01-01

    Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory condition and a leading cause of death, with no available cure. We assessed the actions in pulmonary epithelial cells of peroxisome proliferator-activated receptor ? (PPAR?), a nuclear hormone receptor with anti-inflammatory effects, whose role in COPD is largely unknown. We found that PPAR? was down-regulated in lung tissue and epithelial cells of COPD patients, via both reduced expression and phosphorylation-mediated inhibition, whereas pro-inflammatory nuclear factor-?B (NF-?B) activity was increased. Cigarette smoking is the main risk factor for COPD, and exposing airway epithelial cells to cigarette smoke extract (CSE) likewise down-regulated PPAR? and activated NF-?B. CSE also down-regulated and post-translationally inhibited the glucocorticoid receptor (GR-?) and histone deacetylase 2 (HDAC2), a corepressor important for glucocorticoid action and whose down-regulation is thought to cause glucocorticoid insensitivity in COPD. Treating epithelial cells with synthetic (rosiglitazone) or endogenous (10-nitro-oleic acid) PPAR? agonists strongly up-regulated PPAR? expression and activity, suppressed CSE-induced production and secretion of inflammatory cytokines, and reversed its activation of NF-?B by inhibiting the I?B kinase pathway and by promoting direct inhibitory binding of PPAR? to NF-?B. In contrast, PPAR? knockdown via siRNA augmented CSE-induced chemokine release and decreases in HDAC activity, suggesting a potential anti-inflammatory role of endogenous PPAR?. The results imply that down-regulation of pulmonary epithelial PPAR? by cigarette smoke promotes inflammatory pathways and diminishes glucocorticoid responsiveness, thereby contributing to COPD pathogenesis, and further suggest that PPAR? agonists may be useful for COPD treatment. PMID:24368768

  13. Emergence of hard X-rays at weak nonstationary processes in active regions

    NASA Astrophysics Data System (ADS)

    Vybornov, V. I.; Grigor'eva, I. Yu.; Livshits, M. A.; Ivanov, E. F.

    2015-12-01

    Using Suzaku and Reuven Ramaty High Energy Solar Spectroscopic Image (RHESSI) spacecraft data, we study the characteristics of X-ray emission of weak flares at energies when this emission is generated by fluxes of accelerated electrons. Of the 105 events recorded by a broadband monitor of the entire sky (WAM/Suzaku, with an effective area of ~800 cm2 in the energy range from 50 to 300 keV), we consider 64 B1to C3-class flares. The spectra of these events up to 30 keV are built from RHESSI data. We consider some examples of simultaneous recordings of weak flares occurring from 2005 to 2007. The radiation fluxes measured by WAM/Suzaku at 100 keV have been found to be consistent with those expected from the one-parameter approximation of spectra of the nonthermal radiation recorded by RHESSI at lower energies. The average spectral slope for all events under consideration is 4.30 ± 0.15; i.e., these rare events are significantly stricter than the majority of subflares. This can serve as proof of the fact that the particle acceleration in weak flares is more effective than was previously assumed. As in powerful events, these processes occur in the close vicinity of spots or in places where the neutral line separates hills with a large magnetic field strength.

  14. In vitro screening of 200 pesticides for agonistic activity via mouse peroxisome proliferator-activated receptor (PPAR){alpha} and PPAR{gamma} and quantitative analysis of in vivo induction pathway

    SciTech Connect

    Takeuchi, Shinji; Matsuda, Tadashi; Kobayashi, Satoshi; Takahashi, Tetsuo; Kojima, Hiroyuki . E-mail: kojima@iph.pref.hokkaido.jp

    2006-12-15

    Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors and key regulators of lipid metabolism and cell differentiation. However, there have been few studies reporting on a variety of environmental chemicals, which may interact with these receptors. In the present study, we characterized mouse PPAR{alpha} and PPAR{gamma} agonistic activities of 200 pesticides (29 organochlorines, 11 diphenyl ethers, 56 organophosphorus pesticides, 12 pyrethroids, 22 carbamates, 11 acid amides, 7 triazines, 8 ureas and 44 others) by in vitro reporter gene assays using CV-1 monkey kidney cells. Three of the 200 pesticides, diclofop-methyl, pyrethrins and imazalil, which have different chemical structures, showed PPAR{alpha}-mediated transcriptional activities in a dose-dependent manner. On the other hand, none of the 200 pesticides showed PPAR{gamma} agonistic activity at concentrations {<=} 10{sup -5} M. To investigate the in vivo effects of diclofop-methyl, pyrethrins and imazalil, we examined the gene expression of PPAR{alpha}-inducible cytochrome P450 4As (CYP4As) in the liver of female mice intraperitoneally injected with these compounds ({<=} 300 mg/kg). RT-PCR revealed significantly high induction levels of CYP4A10 and CYP4A14 mRNAs in diclofop-methyl- and pyrethrins-treated mice, whereas imazalil induced almost no gene expressions of CYP4As. In particular, diclofop-methyl induced as high levels of CYP4A mRNAs as WY-14643, a potent PPAR{alpha} agonist. Thus, most of the 200 pesticides tested do not activate PPAR{alpha} or PPAR{gamma} in in vitro assays, but only diclofop-methyl and pyrethrins induce PPAR{alpha} agonistic activity in vivo as well as in vitro.

  15. Synthesis and structure-activity relationship studies in serotonin 5-HT(1A) receptor agonists based on fused pyrrolidone scaffolds.

    PubMed

    Cappelli, Andrea; Manini, Monica; Valenti, Salvatore; Castriconi, Federica; Giuliani, Germano; Anzini, Maurizio; Brogi, Simone; Butini, Stefania; Gemma, Sandra; Campiani, Giuseppe; Giorgi, Gianluca; Mennuni, Laura; Lanza, Marco; Giordani, Antonio; Caselli, Gianfranco; Letari, Ornella; Makovec, Francesco

    2013-05-01

    A new class of serotonin 5-HT1A receptor ligands related to NAN-190, buspirone and aripiprazole has been designed using our potent 5-HT3 receptor ligands as templates. The designed pyrrolidone derivatives 10a-n were prepared by means of the straightforward chemistry consisting in the reaction of the appropriate γ-haloester derivatives with the suitable arylpiperazinylalkylamines. The nanomolar 5-HT1A receptor affinity and the agonist-like profile shown by fused pyrrolidone derivatives 10k,m stimulated the rationalization of the interaction with an homology model of the 5-HT1A receptor and the evaluation of their selectivity profiles and the pharmacokinetic properties. Interestingly, the results of the profiling assays suggested for close congeners 10k,m a significantly divergent binding pattern with compound 10m showing an appreciable selectivity for 5-HT1AR. PMID:23466604

  16. Peroxisome proliferator-activated receptor-γ agonist pioglitazone fails to attenuate renal fibrosis caused by unilateral ureteral obstruction in mice.

    PubMed

    Zhang, Ying; Wang, Jin; Zhou, Qiao-Dan; Zhang, Cong-Hui; Li, Qing; Huang, Shuai; Zhan, Juan; Wang, Kun; Liu, Yan-Yan; Xu, Gang

    2016-02-01

    Renal tubulointerstitial fibrosis is the common ending of progreβsive renal disease. It is worth developing new ways to stop the progreβs of renal fibrosis. Peroxisome proliferator-activated receptor-γ (PPARγ) agonists have been studied to treat diabetic nephropathy, cisplatin-induced acute renal injury, ischemia reperfusion injury and adriamycin nephropathy. In this study, unilateral ureteral obstruction (UUO) was used to establish a different renal fibrosis model. PPAR? agonist pioglitazone was administrated by oral gavage and saline was used as control. At 7th and 14th day after the operation, mice were sacrificed for fibrosis test and T lymphocytes subsets test. Unexpectedly, through MASSON staining, immunohistochemistry for α-SMA, and Western blotting for a-SMA and PDGFR-β, we found that pioglitazone failed to attenuate renal fibrosis in UUO mice. However, flow cytometry showed that pioglitazone down-regulated Th1 cells, and up-regulated Th2 cells, Th17 cells and Treg cells. But the Th17/Treg ratio had no significant change by pioglitazone. Real-time PCR results showed that TGF-β and MCP-1 had no significant changes, at the same time, CD4(+) T cells associated cytokines were partially regulated by pioglitazone pretreatment. Taken together, pioglitazone failed to suppress renal fibrosis progression caused by UUO. PMID:26838738

  17. Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10{sup −/−} mice by attenuating the activation of T cells and promoting their apoptosis

    SciTech Connect

    Singh, Udai P.; Singh, Narendra P.; Singh, Balwan; Price, Robert L.; Nagarkatti, Mitzi; Nagarkatti, Prakash S.

    2012-01-15

    Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10{sup −/−} mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10{sup −/−} mice. After JWH-133 treatment, the percentage of CD4{sup +} T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD. -- Highlights: ► JWH-133, a cannnabinoid receptor-2 agonist ameliorates experimental colitis. ► JWH-133 suppressed inflammation and toxicity to colon by inducing T cell apoptosis. ► JWH-133 decreased mast cells, macrophages, NK cells, IFN-γ{sup +} cells in the LPL. ► AM630, a cannnabinoid receptor-2 antagonist inverted the colitis defense of JWH-133. ► Cannnabinoid receptor-2 may serve as a novel therapeutic target for IBD.

  18. Analysis of the role of receptor number in defining the intrinsic activity and potency of partial agonists in neuroblastoma x glioma hybrid NG108-15 cells transfected to express differing levels of the human beta 2-adrenoceptor.

    PubMed

    MacEwan, D J; Kim, G D; Milligan, G

    1995-08-01

    Many agonist ligands are known experimentally to display a range of efficacies and potencies in different tissues and preparations. To analyze the role of the levels of receptor expression and availability in the intrinsic activities and potencies of agonists, the function of a number of beta-adrenoceptor ligands was examined in clones of neuroblastoma x glioma hybrid NG108-15 cells transfected to express differing levels of the human beta 2-adrenoceptor, as well as after treatment of these cell lines with the irreversible beta-adrenoceptor antagonist bromoacetyl alprenolol menthane (BAAM). Clone beta N22 expressed approximately 10-fold higher levels of the receptor than did clone beta N17. In measurements of agonist stimulation of adenylyl cyclase activity in membranes of these cells or agonist stimulation of the formation of the complex of Gs alpha and adenylyl cyclase, which acts as the high affinity binding site for [3H]forskolin in whole cells, a series of beta-adrenoceptor agonists, including dichloroisoprenaline, ephedrine, dobutamine, and salbutamol, displayed higher intrinsic activity and showed concentration-response curves that were substantially to the left (lower EC50 values) in clone beta N22, compared with clone beta N17. Treatment of clone beta N22 cells with varying concentrations of BAAM reduced the intrinsic activity of these ligands and shifted the concentration-response curves for these agents to the right. In clone beta N22 cells and membranes, reduction in the observed intrinsic activity for ephedrine required elimination of a smaller fraction of the beta 2-adrenoceptor reserve than for salbutamol and reduction in the effect of the full agonists isoprenaline and epinephrine was noted only with high fractional elimination of the receptor pool. The effect of isoprenaline was substantially reduced, however, by BAAM treatment of clone beta N17 cells, where the beta 2-adrenoceptor number approached extremely low levels. Analysis of the data using the formalisms of Whaley et al. [Mol. Pharmacol. 45:481-489 (1994)] showed that prediction of alterations in agonist potency with receptor number for full agonists can be adequately extended to partial agonists. PMID:7651365

  19. (+/-)-Pindolol acts as a partial agonist at atypical beta-adrenoceptors in the guinea pig duodenum.

    PubMed

    Horinouchi, T; Koike, K

    2001-01-01

    The agonistic and antagonistic effects of (+/-)-pindolol (1-(1H-indol-4-yloxy)-3-[(1-methylethyl)amino]-2-propanol) were estimated to clarify whether (+/-)-pindolol acts as a partial agonist on atypical beta-adrenoceptors in the guinea pig duodenum. (+/-)-Pindolol induced concentration-dependent relaxation with a pD2 value of 5.10 +/- 0.03 and an intrinsic activity of 0.83 +/- 0.03. However, the relaxations to (+/-)-pindolol were not antagonized by the non-selective beta1- and beta2-adrenoceptor antagonist (+/-)-propranolol (1 microM). In the presence of (+/-)-propranolol (1 microM), the non-selective beta1-, beta2- and beta3-adrenoceptor antagonist (+/-)-bupranolol (30 microM) induced a rightward shift of the concentration-response curves for (+/-)-pindolol (apparent pA2 = 5.41 +/- 0.06). In the presence of (+/-)-propranolol, (+/-)-pindolol (10 microM) weakly but significantly antagonized the relaxant effects to catecholamines ((-)-isoprenaline, (-)-noradrenaline and (-)-adrenaline), a selective beta3-adrenoceptor agonist BRL37344 ((R*,R*)-(+/-)-4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl) amino]propyl]phenoxyacetic acid sodium salt) and a non-conventional partial beta3-adrenoceptor agonist (+/-)-CGP12177A([4-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,3-dihydro-2H-benzimidazol-2-one] hydrochloride). These results demonstrate that (+/-)-pindolol possesses both agonistic and antagonistic effects on atypical beta-adrenoceptors in the guinea pig duodenum. PMID:11243572

  20. A novel PPAR{gamma} agonist, KR62776, suppresses RANKL-induced osteoclast differentiation and activity by inhibiting MAP kinase pathways

    SciTech Connect

    Park, Ju-Young; Bae, Myung-Ae; Cheon, Hyae Gyeong; Kim, Sung Soo; Hong, Jung-Min; Kim, Tae-Ho; Choi, Je-Yong; Kim, Sang-Hyun; Lim, Jiwon; Choi, Chang-Hyuk; Shin, Hong-In; Kim, Shin-Yoon Park, Eui Kyun

    2009-01-16

    We investigated the effects of a novel peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, KR62776, on osteoclast differentiation and function, and on the underlying signaling pathways. KR62776 markedly suppressed differentiation into osteoclasts in various osteoclast model systems, including bone marrow mononuclear (BMM) cells and a co-culture of calvarial osteoblasts and BMM cells. KR62776 suppressed the activation of tartrate-resistant acid phosphatase (TRAP) and the expression of genes associated with osteoclast differentiation, such as TRAP, dendritic cell-specific transmembrane protein (DC-STAMP), and osteoclast-associated receptor (OSCAR). Furthermore, KR62776 reduced resorption pit formation in osteoclasts, and down-regulated genes essential for osteoclast activity, such as Src and {alpha}v{beta}3 integrin. An analysis of a signaling pathway showed that KR62776 inhibited the receptor activator of nuclear factor-{kappa}B ligand (RANKL)-induced activation of p38 mitogen-activated protein kinase (p38MAPK), extracellular regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and nuclear factor-{kappa}B (NF-{kappa}B). Together, these results demonstrate that KR62776 negatively affects osteoclast differentiation and activity by inhibiting the RANKL-induced activation of MAP kinases and NF-{kappa}B.

  1. Suzaku Observes Weak Flares from IGRJ17391-3021 Representing a Common Low-Activity State in this SFXT

    NASA Technical Reports Server (NTRS)

    Bodaghee, A.; Tomsick, J. A.; Rodriquez, J.; Chaty, S.; Pottschmidt, K.; Walter, R.; Romano, P.

    2010-01-01

    We present an analysis of a 37-ks observation of the supergiant fast X-ray transient (SFXT) IGRJ17391 -3021 (=XTEJ1739-302) gathered with Suzaku. The source evolved from quiescence to a low-activity level culminating in three weak flares lasting approx.3 ks each in which the peak luminosity is only a factor of 5 times that of the pre-flare luminosity. The minimum observed luminosity was 1.3 x 10(exp 33) erg/s (d/2.7 kpc)(exp 2) in the 0.5-10 keV range. The weak flares are accompanied by significant changes in the spectral parameters including a column density (N(sub H) = (4.1(+0.4/-0.5)) x 10(exp 22)/sq cm) that is approx.2-9 times the absorption measured during quiescence. Accretion of obscuring clumps of stellar wind material can explain both the small flares and the increase in NH. Placing this observation in the context of the recent Swift monitoring campaign, we find that weak-flaring episodes, or at least epochs of enhanced activity just above the quiescent level but well below the moderately bright or high-luminosity outbursts, represent more than 60+/-5% of all observations in the 0.5-10keV energy range making this the most common state in the emission behavior of IGRJ17391 -3021.

  2. [New dopaminergic agonists].

    PubMed

    de Mattos, J P; Mattos, V M

    1999-06-01

    We present a brief review of the literature about dopaminergic agonists. We report the five known dopaminergic receptors, where they are located, the advantages and disadvantages of the employment in parkinsonian patients. The dopaminergic agonists were introduced to control the limitations of levodopa-increasing the therapeutic window. We analyse the pharmacocynetic efficacy and the side effects of cabergoline, ropinirole and pramipexole. PMID:10412541

  3. Intramolecular Fluorescence Resonance Energy Transfer (FRET) Sensors of the Orexin OX1 and OX2 Receptors Identify Slow Kinetics of Agonist Activation*

    PubMed Central

    Xu, Tian-Rui; Ward, Richard J.; Pediani, John D.; Milligan, Graeme

    2012-01-01

    Intramolecular fluorescence resonance energy transfer (FRET) sensors able to detect changes in distance or orientation between the 3rd intracellular loop and C-terminal tail of the human orexin OX1 and OX2 G protein-coupled receptors following binding of agonist ligands were produced and expressed stably. These were directed to the plasma membrane and, despite the substantial sequence alterations introduced, in each case were able to elevate [Ca2+]i, promote phosphorylation of the ERK1/2 MAP kinases and become internalized effectively upon addition of the native orexin peptides. Detailed characterization of the OX1 sensor demonstrated that it was activated with rank order of potency orexin A > orexin B > orexin A 16–33, that it bound antagonist ligands with affinity similar to the wild-type receptor, and that mutation of a single residue, D203A, greatly reduced the binding and function of orexin A but not antagonist ligands. Addition of orexin A to individual cells expressing an OX1 sensor resulted in a time- and concentration-dependent reduction in FRET signal consistent with mass-action and potency/affinity estimates for the peptide. Compared with the response kinetics of a muscarinic M3 acetylcholine receptor sensor upon addition of agonist, response of the OX1 and OX2 sensors to orexin A was slow, consistent with a multistep binding and activation process. Such sensors provide means to assess the kinetics of receptor activation and how this may be altered by mutation and sequence variation of the receptors. PMID:22389503

  4. Self-sustained firing activities of the cortical network with plastic rules in weak AC electrical fields

    NASA Astrophysics Data System (ADS)

    Qin, Ying-Mei; Wang, Jiang; Men, Cong; Zhao, Jia; Wei, Xi-Le; Deng, Bin

    2012-07-01

    Both external and endogenous electrical fields widely exist in the environment of cortical neurons. The effects of a weak alternating current (AC) field on a neural network model with synaptic plasticity are studied. It is found that self-sustained rhythmic firing patterns, which are closely correlated with the cognitive functions, are significantly modified due to the self-organizing of the network in the weak AC field. The activities of the neural networks are affected by the synaptic connection strength, the external stimuli, and so on. In the presence of learning rules, the synaptic connections can be modulated by the external stimuli, which will further enhance the sensitivity of the network to the external signal. The properties of the external AC stimuli can serve as control parameters in modulating the evolution of the neural network.

  5. Biphasic dissolution method for quality control and assurance of drugs containing active substances in the form of weak acid salts.

    PubMed

    Franc, Aleš; Muselłk, Jan; Goněc, Roman; Vetchý, David

    2016-03-01

    Substances in the form of weak acid salts have been found to be problematic for dissolution testing. Their absorption can start only after they are turned into the form of an acid following the gastric passage although they were administered in the form of a salt. Due to poor solubility, they cannot be tested in acidic gastric environment for a biased dissolution profile. The biphasic dissolution method is promising for overcoming this obstacle. Tablets with warfarin clathrate sodium salt in two concentrations and two different particle size distributions were tested as a suitable model for finding the medium and process conditions of dissolution. The dissolution method based on the use of the upper organic layer (1-octanol) and the lower aqueous layer 0.1 mol L-1 HCl) was found suitable and discriminatory for tablets containing active substances in the form of salts of weak acids. The method also reflects physical differences in the quality of used substances. PMID:26959550

  6. Agonist-induced activation of histamine H3 receptor signals to extracellular signal-regulated kinases 1 and 2 through PKC-, PLD-, and EGFR-dependent mechanisms.

    PubMed

    Lai, Xiangru; Ye, Lingyan; Liao, Yuan; Jin, Lili; Ma, Qiang; Lu, Bing; Sun, Yi; Shi, Ying; Zhou, Naiming

    2016-04-01

    The histamine H3 receptor (H3R), abundantly expressed in the central and the peripheral nervous system, has been recognized as a promising target for the treatment of various important CNS diseases including narcolepsy, Alzheimer's disease, and attention deficit hyperactivity disorder. The H3R acts via Gi/o -proteins to inhibit adenylate cyclase activity and modulate MAPK activity. However, the underlying molecular mechanisms for H3R mediation of the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) remain to be elucidated. In this study, using HEK293 cells stably expressing human H3R and mouse primary cortical neurons endogenously expressing mouse H3R, we found that the H3R-mediated activation of ERK1/2 was significantly blocked by both the pertussis toxin and the MEK1/2 inhibitor U0126. Upon stimulation by H3R agonist histamine or imetit, H3R was shown to rapidly induce ERK1/2 phosphorylation via PLC/PKC-, PLDs-, and epidermal growth factor receptor (EGFR) transactivation-dependent pathways. Furthermore, it was also indicated that while the βγ-subunits play a key role in H3R-activated ERK1/2 phosphorylation, β-arrestins were not required for ERK1/2 activation. In addition, when the cultured mouse cortical neurons were exposed to oxygen and glucose deprivation conditions (OGD), imetit exhibited neuroprotective properties through the H3R. Treatment of cells with the inhibitor UO126 abolished these protective effects. This suggests a possible neuroprotective role of the H3R-mediated ERK1/2 pathway under hypoxia conditions. These observations may provide new insights into the pharmacological effects and the physiological functions modulated by the H3R-mediated activation of ERK1/2. Histamine H3 receptors are abundantly expressed in the brain and play important roles in various CNS physiological functions. However, the underlying mechanisms for H3R-induced activation of extracellular signal-regulated kinase (ERK)1/2 remain largely unknown. Here, we provide evidence that upon activation by an agonist, H3Rs trigger ERK1/2 activation via phospholipase C/protein kinase C (PLC/PKC)-, phospholipase D (PLD)s-, and matrix metallopeptidase/epidermal growth factor receptor (MMP/EGFR) transactivation-dependent pathways. Moreover, we demonstrate that H3Rs exhibit a neuroprotective effect on the cultured mouse cortical neurons under hypoxia conditions through the ERK1/2 pathway. PMID:26826667

  7. Development of functionally selective, small molecule agonists at kappa opioid receptors.

    PubMed

    Zhou, Lei; Lovell, Kimberly M; Frankowski, Kevin J; Slauson, Stephen R; Phillips, Angela M; Streicher, John M; Stahl, Edward; Schmid, Cullen L; Hodder, Peter; Madoux, Franck; Cameron, Michael D; Prisinzano, Thomas E; Aubé, Jeffrey; Bohn, Laura M

    2013-12-20

    The kappa opioid receptor (KOR) is widely expressed in the CNS and can serve as a means to modulate pain perception, stress responses, and affective reward states. Therefore, the KOR has become a prominent drug discovery target toward treating pain, depression, and drug addiction. Agonists at KOR can promote G protein coupling and βarrestin2 recruitment as well as multiple downstream signaling pathways, including ERK1/2 MAPK activation. It has been suggested that the physiological effects of KOR activation result from different signaling cascades, with analgesia being G protein-mediated and dysphoria being mediated through βarrestin2 recruitment. Dysphoria associated with KOR activation limits the therapeutic potential in the use of KOR agonists as analgesics; therefore, it may be beneficial to develop KOR agonists that are biased toward G protein coupling and away from βarrestin2 recruitment. Here, we describe two classes of biased KOR agonists that potently activate G protein coupling but weakly recruit βarrestin2. These potent and functionally selective small molecule compounds may prove to be useful tools for refining the therapeutic potential of KOR-directed signaling in vivo. PMID:24187130

  8. Development of Functionally Selective, Small Molecule Agonists at Kappa Opioid Receptors*

    PubMed Central

    Zhou, Lei; Lovell, Kimberly M.; Frankowski, Kevin J.; Slauson, Stephen R.; Phillips, Angela M.; Streicher, John M.; Stahl, Edward; Schmid, Cullen L.; Hodder, Peter; Madoux, Franck; Cameron, Michael D.; Prisinzano, Thomas E.; Aubé, Jeffrey; Bohn, Laura M.

    2013-01-01

    The kappa opioid receptor (KOR) is widely expressed in the CNS and can serve as a means to modulate pain perception, stress responses, and affective reward states. Therefore, the KOR has become a prominent drug discovery target toward treating pain, depression, and drug addiction. Agonists at KOR can promote G protein coupling and βarrestin2 recruitment as well as multiple downstream signaling pathways, including ERK1/2 MAPK activation. It has been suggested that the physiological effects of KOR activation result from different signaling cascades, with analgesia being G protein-mediated and dysphoria being mediated through βarrestin2 recruitment. Dysphoria associated with KOR activation limits the therapeutic potential in the use of KOR agonists as analgesics; therefore, it may be beneficial to develop KOR agonists that are biased toward G protein coupling and away from βarrestin2 recruitment. Here, we describe two classes of biased KOR agonists that potently activate G protein coupling but weakly recruit βarrestin2. These potent and functionally selective small molecule compounds may prove to be useful tools for refining the therapeutic potential of KOR-directed signaling in vivo. PMID:24187130

  9. Discovery and Characterization of Biased Allosteric Agonists of the Chemokine Receptor CXCR3.

    PubMed

    Milanos, Lampros; Brox, Regine; Frank, Theresa; Poklukar, Gašper; Palmisano, Ralf; Waibel, Reiner; Einsiedel, Jürgen; Dürr, Maximilian; Ivanović-Burmazović, Ivana; Larsen, Olav; Hjortø, Gertrud Malene; Rosenkilde, Mette Marie; Tschammer, Nuska

    2016-03-10

    In this work we report a design, synthesis, and detailed functional characterization of unique strongly biased allosteric agonists of CXCR3 that contain tetrahydroisoquinoline carboxamide cores. Compound 11 (FAUC1036) is the first strongly biased allosteric agonist of CXCR3 that selectively induces weak chemotaxis and leads to receptor internalization and the β-arrestin 2 recruitment with potency comparable to that of the chemokine CXCL11 without any activation of G proteins. A subtle structural change (addition of a methoxy group, 14 (FAUC1104)) led to a contrasting biased allosteric partial agonist that activated solely G proteins, induced chemotaxis, but failed to induce receptor internalization or β-arrestin 2 recruitment. Concomitant structure-activity relationship studies indicated very steep structure-activity relationships, which steer the ligand bias between the β-arrestin 2 and G protein pathway. Overall, the information presented provides a powerful platform for further development and rational design of strongly biased allosteric agonists of CXCR3. PMID:26862767

  10. Effects of ST1936, a selective serotonin-6 agonist, on electrical activity of putative mesencephalic dopaminergic neurons in the rat brain.

    PubMed

    Borsini, Franco; Bordi, Fabio; Poggi, Andreina; Di Matteo, Vincenzo

    2015-07-01

    The serotonin-6 (5-HT6) receptor is the most recently discovered serotonin receptor, and it represents an increasingly promising target for improving cognition in both normal and disease states. Recently, a new selective 5-HT6 receptor agonist, 2-(5 chloro-2-methyl-1H-indol-3-yl)-N,N-dimethylethanamine (ST1936), with nanomolar affinity for 5-HT6 receptors was described. We performed in-vivo electrophysiological studies to investigate the physiological role of 5-HT6 receptors in the control of the function of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA). Extracellular single-unit recordings were performed from putative dopamine-containing neurons in the SNc and VTA of anesthetised rats. In the SNc, acute systemic administration of ST1936 had no effects on basal firing activity of these dopamine neurons; however, in the VTA, ST1936 induced either dose-related increases (45% of cells) or decreases in basal activity of these dopaminergic neurons. Local application of ST1936 into the VTA caused excitation in all of the dopamine neurons, but had no effects on non-dopamine VTA neurons. Both effects of systemic and microiontophoretic ST1936 were completely reversed by the potent and selective 5-HT6 receptor antagonist 5-chloro-N-(4-methoxy-3-piperazin-1-ylphenyl)-3-methyl-2- benzothiophene-sulfonamide (SB271046). Systemic application of another 5-HT6 agonist, 2-(1-{6-chloroimidazo[2,1-b] [1,3]thiazole-5-sulfonyl}-1H-indol-3-yl)ethan-1-amine (WAY-181187), induced dose-dependent inhibition of these VTA dopaminergic neurons. ST1936 and WAY-181187 appear to have different effects on these VTA dopaminergic neurons, potentially due to different mechanisms of action or to the complexity of 5-HT6 receptor functions. Our data demonstrate the need for further investigations into the use of 5-HT6 receptor agonists to control cognitive disfunction, such as in schizophrenia and depression. PMID:25735994

  11. Synthesis of new potent agonistic analogs of growth hormone-releasing hormone (GHRH) and evaluation of their endocrine and cardiac activities

    PubMed Central

    Cai, Renzhi; Schally, Andrew V.; Cui, Tengjiao; Szalontay, Luca; Halmos, Gabor; Sha, Wei; Kovacs, Magdolna; Jaszberenyi, Miklos; He, Jinlin; Rick, Ferenc G.; Popovics, Petra; Kanashiro-Takeuchi, Rosemeire; Hare, Joshua M.; Block, Norman L.; Zarandi, Marta

    2016-01-01

    In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on cardiomyocytes, pancreatic islets and wound healing, three series of new analogs of GHRH(1–29) have been synthesized and evaluated biologically in an endeavor to produce more potent compounds. “Agmatine analogs”, MR-356 (N-Me-Tyr1-JI-38), MR-361(N-Me-Tyr1, D-Ala2-JI-38) and MR-367(N-Me-Tyr1, D-Ala2, Asn8-JI-38), in which Dat in JI-38 is replaced by N-Me-Tyr1, showed improved relative potencies on GH release upon subcutaneous administration in vivo and binding in vitro. Modification with N-Me-Tyr1 and Arg29-NHCH3 as in MR-403 (N-Me-Tyr1, D-Ala2, Arg29 -NHCH3 -JI-38), MR-406 (N-Me-Tyr1, Arg29 -NHCH3 -JI-38) and MR-409 (N-Me-Tyr1, D-Ala2, Asn8, Arg29-NHCH3 -JI-38), and MR-410 (N-Me-Tyr1, D-Ala2, Thr8, Arg29-NHCH3 -JI-38) resulted in dramatically increased endocrine activities. These appear to be the most potent GHRH agonistic analogs so far developed. Analogs with Apa30-NH2 such as MR-326 (N-Me-Tyr1, D-Ala2, Arg29, Apa30-NH2 -JI-38), and with Gab30 -NH2, as MR-502 (D-Ala2, 5F-Phe6, Ser28, Arg29, Gab30 -NH2 -JI-38) also exhibited much higher potency than JI-38 upon i.v. administration. The relationship between the GH-releasing potency and the analog structure is discussed. Fourteen GHRH agonists with the highest endocrine potencies were subjected to cardiologic tests. MR-409 and MR-356 exhibited higher potency than JI-38 in activating myocardial repair in rats with induced myocardial infarction. As the previous class of analogs, exemplified by JI-38, had shown promising results in multiple fields including cardiology, diabetes and wound healing, our new, more potent, GHRH agonists should manifest additional efficacy for possible medical applications. PMID:24373935

  12. Discovery of CS-2100, a potent, orally active and S1P3-sparing S1P1 agonist.

    PubMed

    Nakamura, Tsuyoshi; Asano, Masayoshi; Sekiguchi, Yukiko; Mizuno, Yumiko; Tamaki, Kazuhiko; Kimura, Takako; Nara, Futoshi; Kawase, Yumi; Shimozato, Takaichi; Doi, Hiromi; Kagari, Takashi; Tomisato, Wataru; Inoue, Ryotaku; Nagasaki, Miyuki; Yuita, Hiroshi; Oguchi-Oshima, Keiko; Kaneko, Reina; Watanabe, Nobuaki; Abe, Yasuyuki; Nishi, Takahide

    2012-02-15

    S1P(3)-sparing S1P(1) agonists have attracted attention as a suppressant of autoimmunity with reduced side effects. Our synthetic efforts and extensive SAR studies led to the discovery of 10b named CS-2100 with the EC(50) value of 4.0 nM for human S1P(1) and over 5000-fold selectivity against S1P(3). The in vivo immunosuppressive efficacy was evaluated in rats on host versus graft reaction and the ID(50) value was determined at 0.407mg/kg. The docking studies of CS-2100 with the homology model of S1P(1) and S1P(3) showed that the ethyl group on the thiophene ring of CS-2100 was sterically hindered by Phe263 in S1P(3), not in the case of Leu276 in S1P(1). This observation gives an explanation for the excellent S1P(3)-sparing characteristic of CS-2100. PMID:22264485

  13. Synthesis and structure activity relationship investigation of triazolo[1,5-a]pyrimidines as CB2 cannabinoid receptor inverse agonists.

    PubMed

    Aghazadeh Tabrizi, Mojgan; Baraldi, Pier Giovanni; Ruggiero, Emanuela; Saponaro, Giulia; Baraldi, Stefania; Poli, Giulio; Tuccinardi, Tiziano; Ravani, Annalisa; Vincenzi, Fabrizio; Borea, Pier Andrea; Varani, Katia

    2016-05-01

    CB2 cannabinoid receptor ligands are known to be therapeutically important for the treatment of numerous diseases. Recently, we have identified the heteroaryl-4-oxopyridine/7-oxopyrimidine derivatives as highly potent and selective CB2 receptor ligands, showing that the pharmakodynamics of the new compounds was controlled by the nature of the heterocycle core. In this paper we describe the synthesis and biological evaluation of 7-oxo-4-pentyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxamide derivatives that led to the identification of novel CB2 receptor inverse agonists. Cyclic AMP experiments on CB2 receptors expressed in CHO cells revealed that introduction of structural modifications at position 2 of triazolopyrimidine template changes the functional activity from partial to inverse agonism. The molecular docking analysis of the novel structures is reported. PMID:26922225

  14. The peroxisome proliferator activated receptor gamma agonist pioglitazone increases functional expression of the glutamate transporter excitatory amino acid transporter 2 (EAAT2) in human glioblastoma cells

    PubMed Central

    Ching, Jared; Amiridis, Stephanie; Stylli, Stanley S.; Bjorksten, Andrew R.; Kountouri, Nicole; Zheng, Thomas; Paradiso, Lucy; Luwor, Rodney B.; Morokoff, Andrew P.; O'Brien, Terence J.; Kaye, Andrew H.

    2015-01-01

    Glioma cells release glutamate through expression of system xc−, which exchanges intracellular glutamate for extracellular cysteine. Lack of the excitatory amino acid transporter 2 (EAAT2) expression maintains high extracellular glutamate levels in the glioma microenvironment, causing excitotoxicity to surrounding parenchyma. Not only does this contribute to the survival and proliferation of glioma cells, but is involved in the pathophysiology of tumour-associated epilepsy (TAE). We investigated the role of the peroxisome proliferator activated receptor gamma (PPARγ) agonist pioglitazone in modulating EAAT2 expression in glioma cells. We found that EAAT2 expression was increased in a dose dependent manner in both U87MG and U251MG glioma cells. Extracellular glutamate levels were reduced with the addition of pioglitazone, where statistical significance was reached in both U87MG and U251MG cells at a concentration of ≥ 30 μM pioglitazone (p < 0.05). The PPARγ antagonist GW9662 inhibited the effect of pioglitazone on extracellular glutamate levels, indicating PPARγ dependence. In addition, pioglitazone significantly reduced cell viability of U87MG and U251MG cells at ≥ 30 μM and 100 μM (p < 0.05) respectively. GW9662 also significantly reduced viability of U87MG and U251MG cells with 10 μM and 30 μM (p < 0.05) respectively. The effect on viability was partially dependent on PPARγ activation in U87MG cells but not U251MG cells, whereby PPARγ blockade with GW9662 had a synergistic effect. We conclude that PPARγ agonists may be therapeutically beneficial in the treatment of gliomas and furthermore suggest a novel role for these agents in the treatment of tumour associated seizures through the reduction in extracellular glutamate. PMID:26046374

  15. The quetiapine active metabolite N-desalkylquetiapine and the neurotensin NTS₁ receptor agonist PD149163 exhibit antidepressant-like effects on operant responding in male rats.

    PubMed

    Hillhouse, Todd M; Shankland, Zachary; Matazel, Katelin S; Keiser, Ashley A; Prus, Adam J

    2014-12-01

    Major depressive disorder is the most common mood disorder in the United States and European Union; however, the limitations of clinically available antidepressant drugs have led researchers to pursue novel pharmacological treatments. Clinical studies have reported that monotherapy with the atypical antipsychotic drug quetiapine produces a rapid reduction in depressive symptoms that is apparent after 1 week of treatment, and it is possible that the active metabolite N-desalkylquetiapine, which structurally resembles an antidepressant drug, produces antidepressant effects. Neuropharmacological evaluations of the neurotensin NTS1 receptor agonist PD149163 suggest antidepressant efficacy, but the effects of a NTS₁ receptor agonist in an antidepressant animal model have yet to be reported. The present study examined the antidepressant-like effects of N-desalkylquetiapine, PD14916, quetiapine, the tricyclic antidepressant drug imipramine, the atypical antipsychotic drug risperidone, and the typical antipsychotic drug raclopride on responding in male Sprague-Dawley rats trained on a differential-reinforcement-of-low-rate 72-s operant schedule, a procedure used for screening antidepressant drugs. Quetiapine, PD149163, risperidone, and imipramine exhibited antidepressant-like effects by increasing the number of reinforcers earned, decreasing the number of responses emitted, and shifting the interresponse time (IRT) distributions to the right. N-Desalkylquetiapine produced a partial antidepressant-like effect by decreasing the number of responses emitted and producing a rightward shift in the IRT distributions, but it did not significantly alter the number of reinforcers earned. Raclopride decreased reinforcers and responses. These data suggest that N-desalkylquetiapine likely contributes to quetiapine's antidepressant efficacy and identify NTS₁ receptor activation as a potential novel pharmacologic strategy for antidepressant drugs. PMID:25285844

  16. Opiate-agonist Induced Taste Aversion Learning in the Fischer 344 and Lewis Inbred Rat Strains: Evidence for Differential Mu Opioid Receptor Activation

    PubMed Central

    Davis, Catherine M.; Rice, Kenner C.; Riley, Anthony L.

    2009-01-01

    The Fischer 344 (F344) and Lewis (LEW) inbred rat strains react differently to morphine in a number of behavioral and physiological preparations, including the acquisition of aversions induced by this compound. The present experiment tested the ability of various compounds with relative selectivity at kappa, delta and mu receptor subtypes to assess the relative roles of these subtypes in mediating the differential aversive effects of morphine in the two strains. In the assessment of the role of the kappa receptor in morphine-induced aversions, animals in both strains were given access to saccharin followed by varying doses of the kappa agonist (−)−U50,488H (0.0, 0.28, 0.90 and 1.60 mg/kg). Although (−)−U50,488H induced aversions in both strains, no strain differences emerged. A separate subset of subjects was trained with the selective delta opioid agonist, SNC80 (0.0, 5.6, 10.0 and 18.0 mg/kg), and again although SNC80 induced aversions, there were no strain differences. Finally, a third subset of subjects was trained with heroin (0.0, 3.2, 5.6 and 10.0 mg/kg), a compound with activity at all three opiate receptor subtypes. Although heroin induced aversions in both strains, the aversions were significantly greater in the F344 strain, suggesting that differential activation of the mu opioid receptor likely mediates the reported strain differences in morphine-induced aversion learning. These data were discussed in terms of strain differences in opioid system functioning and the implications of such differences for other morphine-induced behavioral effects reported in F344 and LEW rats. PMID:19508878

  17. Effects of weak transcranial alternating current stimulation on brain activity-a review of known mechanisms from animal studies.

    PubMed

    Reato, Davide; Rahman, Asif; Bikson, Marom; Parra, Lucas C

    2013-01-01

    Rhythmic neuronal activity is ubiquitous in the human brain. These rhythms originate from a variety of different network mechanisms, which give rise to a wide-ranging spectrum of oscillation frequencies. In the last few years an increasing number of clinical research studies have explored transcranial alternating current stimulation (tACS) with weak current as a tool for affecting brain function. The premise of these interventions is that tACS will interact with ongoing brain oscillations. However, the exact mechanisms by which weak currents could affect neuronal oscillations at different frequency bands are not well known and this, in turn, limits the rational optimization of human experiments. Here we review the available in vitro and in vivo animal studies that attempt to provide mechanistic explanations. The findings can be summarized into a few generic principles, such as periodic modulation of excitability, shifts in spike timing, modulation of firing rate, and shifts in the balance of excitation and inhibition. These effects result from weak but simultaneous polarization of a large number of neurons. Whether this can lead to an entrainment or a modulation of brain oscillations, or whether AC currents have no effect at all, depends entirely on the specific dynamic that gives rise to the different brain rhythms, as discussed here for slow wave oscillations (∼1 Hz) and gamma oscillations (∼30 Hz). We conclude with suggestions for further experiments to investigate the role of AC stimulation for other physiologically relevant brain rhythms. PMID:24167483

  18. CD47 Agonist Peptides Induce Programmed Cell Death in Refractory Chronic Lymphocytic Leukemia B Cells via PLCγ1 Activation: Evidence from Mice and Humans

    PubMed Central

    Attout, Tarik; Boullet, Heloïse; Herbi, Linda; Vela, Laura; Barbier, Sandrine; Chateau, Danielle; Chapiro, Elise; Nguyen-Khac, Florence; Davi, Frédéric; Le Garff-Tavernier, Magali; Moumné, Roba; Sarfati, Marika; Karoyan, Philippe; Merle-Béral, Hélène; Launay, Pierre; Susin, Santos A.

    2015-01-01

    Background Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia, is characterized by the accumulation of abnormal CD5+ B lymphocytes, which results in a progressive failure of the immune system. Despite intense research efforts, drug resistance remains a major cause of treatment failure in CLL, particularly in patients with dysfunctional TP53. The objective of our work was to identify potential approaches that might overcome CLL drug refractoriness by examining the pro-apoptotic potential of targeting the cell surface receptor CD47 with serum-stable agonist peptides. Methods and Findings In peripheral blood samples collected from 80 patients with CLL with positive and adverse prognostic features, we performed in vitro genetic and molecular analyses that demonstrate that the targeting of CD47 with peptides derived from the C-terminal domain of thrombospondin-1 efficiently kills the malignant CLL B cells, including those from high-risk individuals with a dysfunctional TP53 gene, while sparing the normal T and B lymphocytes from the CLL patients. Further studies reveal that the differential response of normal B lymphocytes, collected from 20 healthy donors, and leukemic B cells to CD47 peptide targeting results from the sustained activation in CLL B cells of phospholipase C gamma-1 (PLCγ1), a protein that is significantly over-expressed in CLL. Once phosphorylated at tyrosine 783, PLCγ1 enables a Ca2+-mediated, caspase-independent programmed cell death (PCD) pathway that is not down-modulated by the lymphocyte microenvironment. Accordingly, down-regulation of PLCγ1 or pharmacological inhibition of PLCγ1 phosphorylation abolishes CD47-mediated killing. Additionally, in a CLL-xenograft model developed in NOD/scid gamma mice, we demonstrate that the injection of CD47 agonist peptides reduces tumor burden without inducing anemia or toxicity in blood, liver, or kidney. The limitations of our study are mainly linked to the affinity of the peptides targeting CD47, which might be improved to reach the standard requirements in drug development, and the lack of a CLL animal model that fully mimics the human disease. Conclusions Our work provides substantial progress in (i) the development of serum-stable CD47 agonist peptides that are highly effective at inducing PCD in CLL, (ii) the understanding of the molecular events regulating a novel PCD pathway that overcomes CLL apoptotic avoidance, (iii) the identification of PLCγ1 as an over-expressed protein in CLL B cells, and (iv) the description of a novel peptide-based strategy against CLL. PMID:25734483

  19. The peroxisome proliferator-activated receptor-α (PPAR-α) agonist, AVE8134, attenuates the progression of heart failure and increases survival in rats

    PubMed Central

    Linz, Wolfgang; Wohlfart, Paulus; Baader, Manuel; Breitschopf, Kristin; Falk, Eugen; Schäfer, Hans-Ludwig; Gerl, Martin; Kramer, Werner; Rütten, Hartmut

    2009-01-01

    Aim: To investigate the efficacy of the peroxisome proliferator-activated receptor-α (PPARα) agonist, AVE8134, in cellular and experimental models of cardiac dysfunction and heart failure. Methods: In Sprague Dawley rats with permanent ligation of the left coronary artery (post-MI), AVE8134 was compared to the PPARγ agonist rosiglitazone and in a second study to the ACE inhibitor ramipril. In DOCA-salt sensitive rats, efficacy of AVE8134 on cardiac hypertrophy and fibrosis was investigated. Finally, AVE8134 was administered to old spontaneously hypertensive rats (SHR) at a non-blood pressure lowering dose with survival as endpoint. In cellular models, we studied AVE8134 on hypertrophy in rat cardiomyocytes, nitric oxide signaling in human endothelial cells (HUVEC) and LDL-uptake in human MonoMac-6 cells. Results: In post-MI rats, AVE8134 dose-dependently improved cardiac output, myocardial contractility and relaxation and reduced lung and left ventricular weight and fibrosis. In contrast, rosiglitazone exacerbated cardiac dysfunction. Treatment at AVE8134 decreased plasma proBNP and arginine and increased plasma citrulline and urinary NOx/creatinine ratio. In DOCA rats, AVE8134 prevented development of high blood pressure, myocardial hypertrophy and cardiac fibrosis, and ameliorated endothelial dysfunction. Compound treatment increased cardiac protein expression and phosphorylation of eNOS. In old SHR, treatment with a low dose of AVE8134 improved cardiac and vascular function and increased life expectancy without lowering blood pressure. AVE8134 reduced phenylephrine-induced hypertrophy in adult rat cardiomyocytes. In HUVEC, Ser-1177-eNOS phosphorylation but not eNOS expression was increased. In monocytes, AVE8134 increased the expression of CD36 and the macrophage scavenger receptor 1, resulting in enhanced uptake of oxidized LDL. Conclusion: The PPARα agonist AVE8134 prevents post-MI myocardial hypertrophy, fibrosis and cardiac dysfunction. AVE8134 has beneficial effects against hypertension-induced organ damages, resulting in decreased mortality. The compound exerts its protective properties by a direct effect on cardiomyocyte hypertrophy, but also indirectly via monocyte signaling and increased endothelial NO production. PMID:19503102

  20. Ruling out pyridine dinucleotides as true TRPM2 channel activators reveals novel direct agonist ADP-ribose-2′-phosphate

    PubMed Central

    Tóth, Balázs; Iordanov, Iordan

    2015-01-01

    Transient receptor potential melastatin 2 (TRPM2), a Ca2+-permeable cation channel implicated in postischemic neuronal cell death, leukocyte activation, and insulin secretion, is activated by intracellular ADP ribose (ADPR). In addition, the pyridine dinucleotides nicotinamide-adenine-dinucleotide (NAD), nicotinic acid–adenine-dinucleotide (NAAD), and NAAD-2′-phosphate (NAADP) have been shown to activate TRPM2, or to enhance its activation by ADPR, when dialyzed into cells. The precise subset of nucleotides that act directly on the TRPM2 protein, however, is unknown. Here, we use a heterologously expressed, affinity-purified–specific ADPR hydrolase to purify commercial preparations of pyridine dinucleotides from substantial contaminations by ADPR or ADPR-2′-phosphate (ADPRP). Direct application of purified NAD, NAAD, or NAADP to the cytosolic face of TRPM2 channels in inside-out patches demonstrated that none of them stimulates gating, or affects channel activation by ADPR, indicating that none of these dinucleotides directly binds to TRPM2. Instead, our experiments identify for the first time ADPRP as a true direct TRPM2 agonist of potential biological interest. PMID:25918360

  1. In vivo activity of the thyroid hormone receptor beta- and α-selective agonists GC-24 and CO23 on rat liver, heart, and brain.

    PubMed

    Grijota-Martínez, Carmen; Samarut, Eric; Scanlan, Thomas S; Morte, Beatriz; Bernal, Juan

    2011-03-01

    Thyroid hormone analogs with selective actions through specific thyroid hormone receptor (TR) subtypes are of great interest. They might offer the possibility of mimicking physiological actions of thyroid hormone with receptor subtype or tissue specificity with therapeutic aims. They are also pharmacological tools to dissect biochemical pathways mediated by specific receptor subtypes, in a complementary way to mouse genetic modifications. In this work, we studied the in vivo activity in developing rats of two thyroid hormone agonists, the TRβ-selective GC-24 and the TRα-selective CO23. Our principal goal was to check whether these compounds were active in the rat brain. Analog activity was assessed by measuring the expression of thyroid hormone target genes in liver, heart, and brain, after administration to hypothyroid rats. GC-24 was very selective for TRβ and lacked activity on the brain. On the other hand, CO23 was active in liver, heart, and brain on genes regulated by either TRα or TRβ. This compound, previously shown to be TRα-selective in tadpoles, displayed no selectivity in the rat in vivo. PMID:21239431

  2. Serotonin agonist quipazine induces photic-like phase shifts of the circadian activity rhythm and c-Fos expression in the rat suprachiasmatic nucleus.

    PubMed

    Kohler, M; Kalkowski, A; Wollnik, F

    1999-04-01

    Nonphotic stimuli can reset and entrain circadian activity rhythms in hamsters and mice, and serotonin is thought to be involved in the phase-resetting effects of these stimuli. In the present study, the authors examined the effect of the serotonin agonist quipazine on circadian activity rhythms in three inbred strains of rats (ACI, BH, and LEW). Furthermore, they investigated the effect of quipazine on the expression of c-Fos in the mammalian circadian pacemaker, the suprachiasmatic nucleus (SCN). Quipazine reduced the amount of running wheel activity for 3 h after treatment, however, no long-term changes in tau and in the activity level were observed. More important, quipazine induced significant phase advances of the activity rhythm and c-Fos production in the SCN at the end of the subjective night (Circadian Time [CT] 22), whereas neither phase shifts nor c-Fos induction were observed during the subjective day. Quipazine injections also resulted in moderate phase delays at the beginning of the subjective night (CT 14). A similar phase-response characteristic typically can be observed for photic stimuli. By contrast, nonphotic stimuli normally produce phase advances during the subjective day. The present results suggest species differences between the hamster and the rat with respect to the serotonergic action on circadian timekeeping and indicate that serotonergic pathways play a role in the transmission of photic information to the SCN of rats. PMID:10194650

  3. Secretome of fungus-infected aphids documents high pathogen activity and weak host response.

    PubMed

    Grell, Morten N; Jensen, Annette B; Olsen, Peter B; Eilenberg, Jørgen; Lange, Lene

    2011-04-01

    The discovery of novel secretome proteins can add to our understanding of host-pathogen interactions. Here we report a rich diversity of secreted proteins from the interaction between grain aphids (host, insect order Hemiptera) and fungi of the order Entomophthorales (insect pathogens). The proteins were identified using a unique method unbiased by known sequences or functions to screen a cDNA library constructed directly from field-sampled material. We show for the first time that fungi from the genera Pandora and Entomophthora are armed with a battery of hydrolytic enzymes for penetrating the host cuticle. This enables both access to the hemolymph and exit for sporulation. Further, they secrete enzymes, most notably a number of lipases, for digestion of easily accessible high-energy compounds in the hemolymph. In contrast, we identified only few host genes potentially involved in the interaction, indicating that aphids respond only weakly to the pathogens. These results support recent findings that aphids have a reduced immune repertoire. PMID:21156213

  4. Melanocortin Tetrapeptide Ac-His-DPhe-Arg-Trp-NH2 Modified at the Para Position of the Benzyl Side Chain (DPhe): Importance for Mouse Melanocortin-3 Receptor Agonist versus Antagonist Activity

    PubMed Central

    Proneth, Bettina; Pogozheva, Irina D.; Portillo, Federico P.; Mosberg, Henry I.; Haskell-Luevano, Carrie

    2010-01-01

    The melanocortin-3 and -4 receptors (MC3R, MC4R) have been implicated in energy homeostasis and obesity. Whereas the physiological role of the MC4R is extensively studied, little is known about the MC3R. One caveat is the limited availability of ligands that are selective for the MC3R. Previous studies identified Ac-His-DPhe(p-I)-Arg-Trp-NH2, which possessed partial agonist/antagonist pharmacology at the mMC3R while retaining full nanomolar agonist pharmacology at the mMC4R. These data allowed for the hypothesis that the DPhe position in melanocortin tetrapeptides can be used to examine ligand side-chain determinants important for differentiation of mMC3R agonist versus antagonist activity. A series of 15 DPhe7 modified Ac-His-DPhe7-Arg-Trp-NH2 tetrapeptides has been synthesized and pharmacologically characterized. Most notable results include the identification of modifications that resulted in potent antagonists/partial agonists at the mMC3R and full, potent agonists at the mMC4R. These SAR studies provide experimental evidence that the molecular mechanism of antagonism at the mMC3R differentiates this subtype from the mMC4R. PMID:18800761

  5. The G Protein–Biased κ-Opioid Receptor Agonist RB-64 Is Analgesic with a Unique Spectrum of Activities In Vivo

    PubMed Central

    White, Kate L.; Robinson, J. Elliott; Zhu, Hu; DiBerto, Jeffrey F.; Polepally, Prabhakar R.; Zjawiony, Jordan K.; Nichols, David E.; Malanga, C. J.

    2015-01-01

    The hypothesis that functionally selective G protein–coupled receptor (GPCR) agonists may have enhanced therapeutic benefits has revitalized interest for many GPCR targets. In particular, although κ-opioid receptor (KOR) agonists are analgesic with a low risk of dependence and abuse, their use is limited by a propensity to induce sedation, motor incoordination, hallucinations, and dysphoria-like states. Several laboratories have produced a body of work suggesting that G protein–biased KOR agonists might be analgesic with fewer side effects. Although that has been an intriguing hypothesis, suitable KOR-selective and G protein–biased agonists have not been available to test this idea. Here we provide data using a G protein–biased agonist, RB-64 (22-thiocyanatosalvinorin A), which suggests that KOR-mediated G protein signaling induces analgesia and aversion, whereas β-arrestin-2 signaling may be associated with motor incoordination. Additionally, unlike unbiased KOR agonists, the G protein–biased ligand RB-64 does not induce sedation and does not have anhedonia-like actions, suggesting that a mechanism other than G protein signaling mediates these effects. Our findings provide the first evidence for a highly selective and G protein–biased tool compound for which many, but not all, of the negative side effects of KOR agonists can be minimized by creating G protein–biased KOR agonists. PMID:25320048

  6. Reduced biceps femoris myoelectrical activity influences eccentric knee flexor weakness after repeat sprint running.

    PubMed

    Timmins, R G; Opar, D A; Williams, M D; Schache, A G; Dear, N M; Shield, A J

    2014-08-01

    The aim of this study was to determine whether declines in knee flexor strength following overground repeat sprints were related to changes in hamstrings myoelectrical activity. Seventeen recreationally active men completed maximal isokinetic concentric and eccentric knee flexor strength assessments at 180°/s before and after repeat sprint running. Myoelectrical activity of the biceps femoris (BF) and medial hamstrings (MHs) was measured during all isokinetic contractions. Repeated measures mixed model [fixed factors = time (pre- and post-repeat sprint) and leg (dominant and nondominant), random factor = participants] design was fitted with the restricted maximal likelihood method. Repeat sprint running resulted in significant declines in eccentric, and concentric, knee flexor strength (eccentric = 26 ± 4 Nm, 15% P < 0.001; concentric 11 ± 2 Nm, 10% P < 0.001). Eccentric BF myoelectrical activity was significantly reduced (10%; P = 0.035). Concentric BF and all MH myoelectrical activity were not altered. The declines in maximal eccentric torque were associated with the change in eccentric BF myoelectrical activity (P = 0.013). Following repeat sprint running, there were preferential declines in the myoelectrical activity of the BF, which explained declines in eccentric knee flexor strength. PMID:24422638

  7. The Role of Peroxisome Proliferator-Activated Receptor and Effects of Its Agonist, Pioglitazone, on a Rat Model of Optic Nerve Crush: PPARγ in Retinal Neuroprotection

    PubMed Central

    Zhu, Juming; Zhang, Junfang; Ji, Min; Gu, Hongwei; Xu, Yue; Chen, Chen; Hu, Nan

    2013-01-01

    It has been shown that peroxisome proliferators-activated receptor gamma (PPARγ) is beneficial for central nervous system injury. However its role on optic nerve injury remains unknown. In the present study, we examined the change of PPARγ expression in rat retina following optic nerve injury and investigated the effect of pioglitazone (Pio), a PPARγ agonist, on retinal ganglion cells (RGCs) neuroprotection using a rat optic nerve crush (ONC) model. Our results showed that PPARγ mRNA and protein levels were increased after ONC, and most of PPARγ-immunoreactive cells colocalized with Müller cells. Pio treatment significantly enhanced the number of surviving RGCs and inhibited RGCs apoptosis induced by ONC. However, when PPARγ antagonist GW9662 was used, these neuroprotective effects were abolished. In addition, pio attenuated Müller cell activation after ONC. These results indicate that PPARγ appears to protect RGCs from ONC possibly via the reduction of Müller glial activation. It provides evidence that activation of PPARγ may be a potential alternative treatment for RGCs neuroprotection. PMID:23874818

  8. Design, synthesis, and biological evaluation of a series of alkoxy-3-indolylacetic acids as peroxisome proliferator-activated receptor γ/δ agonists.

    PubMed

    Gim, Hyo Jin; Li, Hua; Jeong, Ji Hye; Lee, Su Jeong; Sung, Mi-Kyung; Song, Mi-Young; Park, Byung-Hyun; Oh, Soo Jin; Ryu, Jae-Ha; Jeon, Raok

    2015-07-01

    A series of alkoxy-3-indolylacetic acid analogs has been discovered as peroxisome proliferator-activated receptor (PPAR) agonists. Structure-activity relationship study indicated that PPARα/γ/δ activities were dependent on the nature of the hydrophobic group, the attachment position of the alkoxy linker to the indole ring, and N-alkylation of indole nitrogen. Some compounds presented significant PPARγ/δ activity and molecular modeling suggested their putative binding modes in the ligand binding domain of PPARγ. Of these, compound 51 was selected for in vivo study via an evaluation of microsomal stability in mouse and human liver. Compound 51 lowered the levels of fasting blood glucose, insulin, and HbA1c without gain in body weight in db/db mice. When compound 51 was treated, hepatic triglycerides level and the size of adipocytes in white adipose tissue of db/db mice were also reduced as opposed to treatment with rosiglitazone. Taken together, compound 51 shows high potential warranting further studies in models for diabetes and related metabolic disorders and may be in use as a chemical tool for the understanding of PPAR biology. PMID:25982078

  9. Norepinephrine and endothelin activate diacylglycerol kinases in caveolae/rafts of rat mesenteric arteries: agonist-specific role of PI3-kinase.

    PubMed

    Clarke, Christopher J; Ohanian, Vasken; Ohanian, Jacqueline

    2007-05-01

    The phosphatidylinositol (PI) signaling pathway mediates norepinephrine (NE)- and endothelin-1 (ET-1)-stimulated vascular smooth muscle contraction through an inositol-trisphosphate-induced rise in intracellular calcium and diacylglycerol (DG) activation of protein kinase C (PKC). Subsequent activation of DG kinases (DGKs) metabolizes DG to phosphatidic acid (PA), potentially regulating PKC activity. Because precise regulation and spatial restriction of the PI pathway is necessary for specificity, we have investigated whether this occurs within caveolae/rafts, specialized plasma membrane microdomains implicated in vascular smooth muscle contraction. We show that components of the PI signaling cascade-phosphatidylinositol 4,5-bisphosphate (PIP(2)), PA, and DGK-theta are present in caveolae/rafts prepared from rat mesenteric small arteries. Stimulation with NE or ET-1 induced [(33)P]PIP(2) hydrolysis solely within caveolae/rafts. NE stimulated an increase in DGK activity in caveolae/rafts alone, whereas ET-1 activated DGK in caveolae/rafts and noncaveolae/rafts; however, [(33)P]PA increased in all fractions with both agonists. Previously, we reported that NE activated DGK-theta in a phosphatidylinositol 3-kinase (PI3-kinase)-dependent manner; here, we describe PI3-kinase-dependent DGK activation and [(33)P]PA production in caveolae/rafts in response to NE but not ET-1. Additionally, PKB, a potential activator of DGK-theta, translocated to caveolae/rafts in response to NE but not ET-1, and PI3-kinase inhibition prevented this. Furthermore, PI3-kinase inhibition reduced the sensitivity of contraction to NE but not ET-1. Our study shows that caveolae/rafts are major sites of vasoconstrictor hormone activation of the PI pathway in intact small arteries and suggest a link between lipid signaling events within caveolae/rafts and contraction. PMID:17208990

  10. 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

  11. GPR119 agonists: a promising approach for T2DM treatment? A SWOT analysis of GPR119.

    PubMed

    Kang, Sang-Uk

    2013-12-01

    Ever since its advent as a promising therapeutic target for type 2 diabetes mellitus (T2DM), G-protein-coupled receptor 119 (GPR119) has received much interest from the pharmaceutical industry. This interest peaked in June 2010, when Sanofi-Aventis agreed to pay Metabolex (Cymabay Therapeutics) US$375 million for MBX-2982, which was a representative orally active GPR119 agonist. However, Sanofi-Aventis opted to terminate the deal in May 2011 and another leading GPR119 agonist, GSK1292263, had a loss of efficacy during its clinical trial. In this review, I discuss the pros and cons of GPR119 through a strengths, weaknesses, opportunities, and threats (SWOT) analysis and propose development strategies for the eventual success of a GPR119 agonist development program. PMID:24060477

  12. Physical activity: benefit or weakness in metabolic adaptations in a mouse model of chronic food restriction?

    PubMed

    Méquinion, Mathieu; Caron, Emilie; Zgheib, Sara; Stievenard, Aliçia; Zizzari, Philippe; Tolle, Virginie; Cortet, Bernard; Lucas, Stéphanie; Prévot, Vincent; Chauveau, Christophe; Viltart, Odile

    2015-02-01

    In restrictive-type anorexia nervosa (AN) patients, physical activity is usually associated with food restriction, but its physiological consequences remain poorly characterized. In female mice, we evaluated the impact of voluntary physical activity with/without chronic food restriction on metabolic and endocrine parameters that might contribute to AN. In this protocol, FRW mice (i.e., food restriction with running wheel) reached a crucial point of body weight loss (especially fat mass) faster than FR mice (i.e., food restriction only). However, in contrast to FR mice, their body weight stabilized, demonstrating a protective effect of a moderate, regular physical activity. Exercise delayed meal initiation and duration. FRW mice displayed food anticipatory activity compared with FR mice, which was strongly diminished with the prolongation of the protocol. The long-term nature of the protocol enabled assessment of bone parameters similar to those observed in AN patients. Both restricted groups adapted their energy metabolism differentially in the short and long term, with less fat oxidation in FRW mice and a preferential use of glucose to compensate for the chronic energy imbalance. Finally, like restrictive AN patients, FRW mice exhibited low leptin levels, high plasma concentrations of corticosterone and ghrelin, and a disruption of the estrous cycle. In conclusion, our model suggests that physical activity has beneficial effects on the adaptation to the severe condition of food restriction despite the absence of any protective effect on lean and bone mass. PMID:25465889

  13. Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, independently of PPAR{gamma} in human glioma cells

    SciTech Connect

    Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung; Kim, Hye Jin; Yang, Jin Mo; Ryu, Somi; Noh, Yoo Hun; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Yoo, Keon Hee; Koo, Hong Hoe; Sung, Ki Woong

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Greater than 30 {mu}M ciglitazone induces cell death in glioma cells. Black-Right-Pointing-Pointer Cell death by ciglitazone is independent of PPAR{gamma} in glioma cells. Black-Right-Pointing-Pointer CGZ induces cell death by the loss of MMP via decreased Akt. -- Abstract: Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPAR{gamma} in CGZ-induced cell death was examined. At concentrations of greater than 30 {mu}M, CGZ, a synthetic PPAR{gamma} agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 {mu}M CGZ effectively induced cell death after pretreatment with 30 {mu}M of the PPAR{gamma} antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPAR{gamma} was down-regulated cells by siRNA, lower concentrations of CGZ (<30 {mu}M) were sufficient to induce cell death, although higher concentrations of CGZ ( Greater-Than-Or-Slanted-Equal-To 30 {mu}M) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPAR{gamma}. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPAR{gamma} in glioma cells, by down-regulating Akt activity and inducing MMP collapse.

  14. Creatine Kinase Activity Weakly Correlates to Volume Completed Following Upper Body Resistance Exercise

    ERIC Educational Resources Information Center

    Machado, Marco; Willardson, Jeffrey M.; Silva, Dailson P.; Frigulha, Italo C.; Koch, Alexander J.; Souza, Sergio C.

    2012-01-01

    In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min…

  15. Creatine Kinase Activity Weakly Correlates to Volume Completed Following Upper Body Resistance Exercise

    ERIC Educational Resources Information Center

    Machado, Marco; Willardson, Jeffrey M.; Silva, Dailson P.; Frigulha, Italo C.; Koch, Alexander J.; Souza, Sergio C.

    2012-01-01

    In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min

  16. Synergistic activity between the delta-opioid agonist SNC80 and amphetamine occurs via a glutamatergic NMDA-receptor dependent mechanism

    PubMed Central

    Bosse, Kelly E.; Jutkiewicz, Emily M.; Schultz, Kristin N.; Mabrouk, Omar S.; Kennedy, Robert T.; Gnegy, Margaret E.; Traynor, John R.

    2014-01-01

    Glutamate is known to cause the release of dopamine through a Ca2+-sensitive mechanism that involves activation of NMDA ionotropic glutamate receptors. In the current study, we tested the hypothesis that the delta opioid agonist SNC80 acts indirectly, via the glutamatergic system, to enhance both amphetamine-stimulated dopamine efflux from striatal preparations and amphetamine-stimulated locomotor activity. SNC80 increased extracellular glutamate content, which was accompanied by a concurrent decrease in GABA levels. Inhibition of NMDA signaling with the selective antagonist MK801 blocked the enhancement of both amphetamine-induced dopamine efflux and hyperlocomotion observed with SNC80 pretreatment. Addition of exogenous glutamate also potentiated amphetamine-stimulated dopamine efflux in a Mg2+- and MK801-sensitive manner. After removal of Mg2+ to relieve the ion conductance inhibition of NMDA receptors, SNC80 both elicited dopamine release alone and produced a greater enhancement of amphetamine-evoked dopamine efflux. The action of SNC80 to enhance amphetamine-evoked dopamine efflux was mimicked by the GABAB antagonist 2-hydroxysaclofen. These cumulative findings suggest SNC80 modulates amphetamine-stimulated dopamine efflux through an intra-striatal mechanism involving inhibition of GABA transmission leading to the local release of glutamate followed by subsequent activation of NMDA receptors. PMID:24035916

  17. Agonist-like activity of antibodies directed against the second extracellular loop of the human cardiac serotonin 5-HT4(e) receptor in transfected COS-7 cells.

    PubMed

    Bozon, V; Di Scala, E; Eftekhari, P; Hoebeke, J; Lezoualc'h, F; Fischmeister, R; Argibay, J

    2002-01-01

    We have previously reported that antipeptide antibodies directed against the second extracellular loop of the cardiac h5-HT4 receptor could block the activation of the L-type Ca channel in human atrial cardiomyocytes. In this paper we investigate the immunological and physiological activity of these antibodies, in a cell system expressing a larger amount of receptors than the atrial cells. The recombinant receptor was expressed at the surface of COS-7 cells under an active form (serotonin, EC50 = 1.81 x 10(-7) M), at a high level (375 +/- 25 fmol receptor/mg total protein) and was able to bind a specific ligand (GR113808) with a high affinity (Kd = 0.28 +/- 0.05 nM). In this system, the same anti-peptide antibodies used for the cardiac cells induced an "agonist-like" effect on the recombinant h5-HT4 receptor. These results are in line with those shown for others G-protein coupled receptors, as adrenoreceptors. In addition, this work showed that the effect of the antibodies is not only dependent on the epitopic region recognised but also on the molecular density and/or the cellular environment of the target receptors. Finally, our results support the hypothesis that the h5-HT4 receptor could be a new target for autoantibodies in patients with atrial arrhythmia. PMID:12448792

  18. Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles

    SciTech Connect

    Speck, Thomas; Menzel, Andreas M.; Bialké, Julian; Löwen, Hartmut

    2015-06-14

    Recently, we have derived an effective Cahn-Hilliard equation for the phase separation dynamics of active Brownian particles by performing a weakly non-linear analysis of the effective hydrodynamic equations for density and polarization [Speck et al., Phys. Rev. Lett. 112, 218304 (2014)]. Here, we develop and explore this strategy in more detail and show explicitly how to get to such a large-scale, mean-field description starting from the microscopic dynamics. The effective free energy emerging from this approach has the form of a conventional Ginzburg-Landau function. On the coarsest scale, our results thus agree with the mapping of active phase separation onto that of passive fluids with attractive interactions through a global effective free energy (motility-induced phase transition). Particular attention is paid to the square-gradient term necessary for the phase separation kinetics. We finally discuss results from numerical simulations corroborating the analytical results.

  19. The E6 and E7 genes of human papillomavirus type 6 have weak immortalizing activity in human epithelial cells.

    PubMed Central

    Halbert, C L; Demers, G W; Galloway, D A

    1992-01-01

    Previous studies have shown that the E7 gene of human papillomavirus (HPV) type 16 or 18 alone was sufficient for immortalization of human foreskin epithelial cells (HFE) and that the efficiency was increased in cooperation with the respective E6 gene, whereas the HPV6 E6 or E7 gene was not active in HFE. To detect weak immortalizing activities of the HPV6 genes, cells were infected with recombinant retroviruses containing HPV genes, alone and in homologous and heterologous combinations. The HPV6 genes, alone or together (HPV6 E6 plus HPV6 E7), were not able to immortalize cells. However the HPV6 E6 gene, in concert with HPV16 E7, increased the frequency of immortalization threefold over that obtained with HPV16 E7 alone. Interestingly, 6 of 20 clones containing the HPV16 E6 gene and the HPV6 E7 gene were immortalized, whereas neither gene alone was sufficient. Thus, the HPV6 E6 and E7 genes have weak immortalizing activities which can be detected in cooperation with the more active transforming genes of HPV16. Acute expression of the HPV6 and HPV16 E6 and E7 genes revealed that only HPV16 E7 was able to stimulate the proliferation of cells in organotypic culture, resulting in increased expression of the proliferative cell nuclear antigen and the formation of a disorganized epithelial layer. Additionally, combinations of genes that immortalized HFE cells (HPV16 E6 plus HPV16 E7, HPV16 E6 plus HPV6 E7, and HPV6 E6 plus HPV16 E7) also stimulated proliferation. Images PMID:1312623

  20. Resveratrol dimers, nutritional components in grape wine, are selective ROS scavengers and weak Nrf2 activators.

    PubMed

    Li, Chang; Xu, Xiaofei; Tao, Zhihao; Wang, Xiu Jun; Pan, Yuanjiang

    2015-04-15

    Resveratrol monomer (Res) and its oligomers are considered as nutritional components distributed in edible plants. Three naturally occurring resveratrol dimers, namely parthenocissin A (Par), quadrangularin A (Qua) and pallidol (Pal), were synthesized and evaluated for their ability to scavenge reactive oxygen species (ROS) and to activate the transcription factor Nrf2, which regulates cellular antioxidant systems. In vitro studies with different ROS and radical assay models showed that all the three dimers are strong DPPH quenchers and selective singlet oxygen ((1)O2) scavengers (IC50=4.90, 1.05 and 5.50 μM, respectively). However, they were ineffective against hydroxyl radical (OH) or superoxide anion (O2(-)). Exposing the dimers to an antioxidant response element (ARE) reporter cell line revealed that only pallidol was able to activate Nrf2 at 30 μM, while parthenocissin A and quadrangularin A had no significant effect on Nrf2. Our data demonstrates the distinct difference between reservatrol monomer and its dimers in activating the Nrf2/ARE signalling pathway. PMID:25466015

  1. Eccentric exercise and delayed onset muscle soreness of the quadriceps induce adjustments in agonist-antagonist activity, which are dependent on the motor task.

    PubMed

    Vila-Chã, C; Hassanlouei, H; Farina, D; Falla, D

    2012-02-01

    This study investigates the effects of eccentric exercise and delayed onset muscle soreness (DOMS) of the quadriceps on agonist-antagonist activity during a range of motor tasks. Ten healthy volunteers (age, mean ± SD, 24.9 ± 3.2 years) performed maximum voluntary contractions (MVC) and explosive isometric contractions of the knee extensors followed by isometric contractions at 2.5, 5, 10, 15, 20, and 30% MVC at baseline, immediately after and 24 h after eccentric exercise of the quadriceps. During each task, force of the knee extensors and surface EMG of the vasti and hamstrings muscles were recorded concurrently. Rate of force development (RFD) was computed from the explosive isometric contraction, and the coefficient of variation of the force (CoV) signal was estimated from the submaximal contractions. Twenty-four hours after exercise, the subjects rated their perceived pain intensity as 4.1 ± 1.2 (score out of 10). The maximum RFD and MVC of the knee extensors was reduced immediately post- and 24 h after eccentric exercise compared to baseline (average across both time points: 19.1 ± 17.1% and 11.9 ± 9.8% lower, respectively, P < 0.05). The CoV for force during the submaximal contractions was greater immediately after eccentric exercise (up to 66% higher than baseline, P < 0.001) and remained higher 24 h post-exercise during the presence of DOMS (P < 0.01). For the explosive and MVC tasks, the EMG amplitude of the vasti muscles decreased immediately after exercise and was accompanied by increased antagonist EMG for the explosive contraction only. On the contrary, reduced force steadiness was accompanied by a general increase in EMG amplitude of the vasti muscles and was accompanied by increased antagonist activity, but only at higher force levels (>15% MVC). This study shows that eccentric exercise and subsequent DOMS of the quadriceps reduce the maximal force, rate of force development and force steadiness of the knee extensors, and is accompanied by different adjustments of agonist and antagonist muscle activities. PMID:22094715

  2. Modulation of Innate Immune Responses via Covalently Linked TLR Agonists

    PubMed Central

    2015-01-01

    We present the synthesis of novel adjuvants for vaccine development using multivalent scaffolds and bioconjugation chemistry to spatially manipulate Toll-like receptor (TLR) agonists. TLRs are primary receptors for activation of the innate immune system during vaccination. Vaccines that contain a combination of small and macromolecule TLR agonists elicit more directed immune responses and prolong responses against foreign pathogens. In addition, immune activation is enhanced upon stimulation of two distinct TLRs. Here, we synthesized combinations of TLR agonists as spatially defined tri- and di-agonists to understand how specific TLR agonist combinations contribute to the overall immune response. We covalently conjugated three TLR agonists (TLR4, 7, and 9) to a small molecule core to probe the spatial arrangement of the agonists. Treating immune cells with the linked agonists increased activation of the transcription factor NF-κB and enhanced and directed immune related cytokine production and gene expression beyond cells treated with an unconjugated mixture of the same three agonists. The use of TLR signaling inhibitors and knockout studies confirmed that the tri-agonist molecule activated multiple signaling pathways leading to the observed higher activity. To validate that the TLR4, 7, and 9 agonist combination would activate the immune response to a greater extent, we performed in vivo studies using a vaccinia vaccination model. Mice vaccinated with the linked TLR agonists showed an increase in antibody depth and breadth compared to mice vaccinated with the unconjugated mixture. These studies demonstrate how activation of multiple TLRs through chemically and spatially defined organization assists in guiding immune responses, providing the potential to use chemical tools to design and develop more effective vaccines. PMID:26640818

  3. AvrRpm1 Missense Mutations Weakly Activate RPS2-Mediated Immune Response in Arabidopsis thaliana

    PubMed Central

    Cherkis, Karen A.; Temple, Brenda R. S.; Chung, Eui-Hwan; Sondek, John; Dangl, Jeffery L.

    2012-01-01

    Plants recognize microbes via specific pattern recognition receptors that are activated by microbe-associated molecular patterns (MAMPs), resulting in MAMP-triggered immunity (MTI). Successful pathogens bypass MTI in genetically diverse hosts via deployment of effectors (virulence factors) that inhibit MTI responses, leading to pathogen proliferation. Plant pathogenic bacteria like Pseudomonas syringae utilize a type III secretion system to deliver effectors into cells. These effectors can contribute to pathogen virulence or elicit disease resistance, depending upon the host plant genotype. In disease resistant genotypes, intracellular immune receptors, typically belonging to the nucleotide binding leucine-rich repeat family of proteins, perceive bacterial effector(s) and initiate downstream defense responses (effector triggered immunity) that include the hypersensitive response, and transcriptional re-programming leading to various cellular outputs that collectively halt pathogen growth. Nucleotide binding leucine-rich repeat sensors can be indirectly activated via perturbation of a host protein acting as an effector target. AvrRpm1 is a P. syringae type III effector. Upon secretion into the host cell, AvrRpm1 is acylated by host enzymes and directed to the plasma membrane, where it contributes to virulence. This is correlated with phosphorylation of Arabidopsis RIN4 in vivo. RIN4 is a negative regulator of MAMP-triggered immunity, and its modification in the presence of four diverse type III effectors, including AvrRpm1, likely enhances this RIN4 regulatory function. The RPM1 nucleotide binding leucine-rich repeat sensor perceives RIN4 perturbation in disease resistant plants, leading to a successful immune response. Here, demonstrate that AvrRpm1 has a fold homologous to the catalytic domain of poly(ADP-ribosyl) polymerase. Site-directed mutagenesis of each residue in the putative catalytic triad, His63-Tyr122-Asp185 of AvrRpm1, results in loss of both AvrRpm1-dependent virulence and AvrRpm1-mediated activation of RPM1, but, surprisingly, causes a gain of function: the ability to activate the RPS2 nucleotide binding leucine-rich repeat sensor. PMID:22880057

  4. Cannabinoid Receptor Type 2 Agonist Attenuates Apoptosis by Activation of Phosphorylated CREB-Bcl-2 Pathway After Subarachnoid Hemorrhage in Rats

    PubMed Central

    Fujii, Mutsumi; Sherchan, Prativa; Soejima, Yoshiteru; Hasegawa, Yu; Flores, Jerry; Doycheva, Desislava; Zhang, John H.

    2014-01-01

    Early brain injury (EBI) which comprises of vasogenic edema and apoptotic cell death is an important component of subarachnoid hemorrhage (SAH) pathophysiology. This study evaluated whether Cannabinoid receptor type 2 (CB2R) agonist, JWH133, attenuates EBI after SAH and whether CB2R stimulation reduces pro-apoptotic caspase-3 via up-regulation of cAMP response element-binding protein (CREB)-Bcl-2 signaling pathway. Male Sprague Dawley rats (n=123) were subjected to SAH by endovascular perforation. Rats received vehicle or JWH133 at 1 hour after SAH. Neurological deficits and brain water content were evaluated at 24 hours after SAH. Western blot was performed to quantify phosphorylated CREB (pCREB), Bcl-2, and cleaved caspase-3 levels. Neuronal cell death was evaluated with terminal deoxynucleotidyl transferase-mediated uridine 5′-triphosphate-biotin nick end-labeling staining. Additionally, CREB siRNA was administered to manipulate the proposed pathway. JWH133 (1.0 mg/kg) improved neurological deficits and reduced brain water content in left hemisphere 24 hours after SAH. JWH133 significantly increased activated CREB (pCREB) and Bcl-2 levels and significantly decreased cleaved caspase-3 levels in left hemisphere 24 hours after SAH. CREB siRNA reversed the effects of treatment. TUNEL positive neurons in the cortex were reduced with JWH133 treatment. Thus, CB2R stimulation attenuated EBI after SAH possibly through activation of pCREB-Bcl-2 pathway. PMID:25058046

  5. The evolution from weak to strong geomagnetic activity - An interpretation in terms of deterministic chaos

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Klimas, A. J.; Mcpherron, R. L.; Buechner, J.

    1990-01-01

    An analogue of the magnetosphere developed on the basis of Shaw's (1984) dripping faucet model was used to model the mechanisms of the magnetospheric response to energy transfer from the solar wind. It is demonstrated that geomagnetic activity results from nonlinearly coupled physical processes and that the strength and the nature of the coupling changes dramatically as the magnetosphere is driven harder and harder by increasing energy input. Based on initial results obtained from the model, is is suggested that a chaotic transition takes place in the analogue system as the loading rate is increased beyond a critical value. This model is able to explain many of the features in the results of linear prediction filtering techniques.

  6. Peroxisome proliferator-activated receptor {alpha} agonists modulate Th1 and Th2 chemokine secretion in normal thyrocytes and Graves' disease

    SciTech Connect

    Antonelli, Alessandro; Ferrari, Silvia Martina; Frascerra, Silvia; Corrado, Alda; Pupilli, Cinzia; Bernini, Giampaolo; Benvenga, Salvatore; Ferrannini, Ele; Fallahi, Poupak

    2011-07-01

    Until now, no data are present about the effect of peroxisome proliferator-activated receptor (PPAR){alpha} activation on the prototype Th1 [chemokine (C-X-C motif) ligand (CXCL)10] (CXCL10) and Th2 [chemokine (C-C motif) ligand 2] (CCL2) chemokines secretion in thyroid cells. The role of PPAR{alpha} and PPAR{gamma} activation on CXCL10 and CCL2 secretion was tested in Graves' disease (GD) and control primary thyrocytes stimulated with interferon (IFN){gamma} and tumor necrosis factor (TNF){alpha}. IFN{gamma} stimulated both CXCL10 and CCL2 secretion in primary GD and control thyrocytes. TNF{alpha} alone stimulated CCL2 secretion, while had no effect on CXCL10. The combination of IFN{gamma} and TNF{alpha} had a synergistic effect both on CXCL10 and CCL2 chemokines in GD thyrocytes at levels comparable to those of controls. PPAR{alpha} activators inhibited the secretion of both chemokines (stimulated with IFN{gamma} and TNF{alpha}) at a level higher (for CXCL10, about 60-72%) than PPAR{gamma} agonists (about 25-35%), which were confirmed to inhibit CXCL10, but not CCL2. Our data show that CCL2 is modulated by IFN{gamma} and TNF{alpha} in GD and normal thyrocytes. Furthermore we first show that PPAR{alpha} activators inhibit the secretion of CXCL10 and CCL2 in thyrocytes, suggesting that PPAR{alpha} may be involved in the modulation of the immune response in the thyroid.

  7. The cAMP-producing agonist beraprost inhibits human vascular smooth muscle cell migration via exchange protein directly activated by cAMP

    PubMed Central

    McKean, Jenny S.; Murray, Fiona; Gibson, George; Shewan, Derryck A.; Tucker, Steven J.; Nixon, Graeme F.

    2015-01-01

    Aims During restenosis, vascular smooth muscle cells (VSMCs) migrate from the vascular media to the developing neointima. Preventing VSMC migration is therefore a therapeutic target for restenosis. Drugs, such as prostacyclin analogues, that increase the intracellular concentration of cyclic adenosine monophosphate (cAMP) can inhibit VSMC migration, but the mechanisms via which this occurs are unknown. Two main downstream mediators of cAMP are protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). This study has examined the effects of the prostacyclin analogue beraprost on VSMC migration and investigated the intracellular pathways involved. Methods and results In a chemotaxis chamber, human saphenous vein VSMC migrated towards a platelet-derived growth-factor-BB (PDGF) chemogradient. Incubation with therapeutically relevant concentrations of cAMP-producing agonist beraprost significantly decreased PDGF-induced migration. Direct activation of either PKA or Epac inhibited migration whereas inhibition of PKA did not prevent the anti-migratory effect of beraprost. Direct activation of Epac also prevented hyperplasia in ex vivo serum-treated human veins. Using fluorescence resonance energy transfer, we demonstrated that beraprost activated Epac but not PKA. The mechanisms of this Epac-mediated effect involved activation of Rap1 with subsequent inhibition of RhoA. Cytoskeletal rearrangement at the leading edge of the cell was consequently inhibited. Interestingly, Epac1 was localized to the leading edge of migrating VSMC. Conclusions These results indicate that therapeutically relevant concentrations of beraprost can inhibit VSMC migration via a previously unknown mechanism involving the cAMP mediator Epac. This may provide a novel target that could blunt neointimal formation. PMID:26092100

  8. Activation of the Liver X Receptor by Agonist TO901317 Improves Hepatic Insulin Resistance via Suppressing Reactive Oxygen Species and JNK Pathway

    PubMed Central

    Dong, Ying; Gao, Guirong; Fan, Hongyan; Li, Shengxian; Li, Xuhang; Liu, Wei

    2015-01-01

    Activation of Liver X receptors (LXRs), key transcriptional regulators of glucose metabolism, normalizes glycemia and improves insulin sensitivity in rodent models with insulin resistance. However, the molecular mechanism is unclear. This study is aimed to elucidate the mechanism of LXRs-mediated liver glucose metabolic regulation in vitro and in vivo. Db/db mice were used as an in vivo model of diabetes; palmitate (PA)-stimulated HepG2 cells were used as an in vitro cell model with impairment of insulin signaling. TO901317 (TO) was chosen as the LXRs agonist. We demonstrated that TO treatment for 14 days potently improved the hepatic glucose metabolism in db/db mice, including fasting blood glucose, fasting insulin level, and HOMA-IR. TO had no effect on the glucose metabolism in normal WT mice. TO-mediated activation of hepatic LXRs led to strong inhibition of ROS production accompanied by inactivation of JNK pathway and re-activation of Akt pathway. TO also suppressed the expression of gluconeogenic genes such as PEPCK and G-6-pase in db/db mice, but not in WT mice. In HepG2 cells, TO almost completely restored PA-induced Akt inactivation, and suppressed PA-stimulated ROS production and JNK activation. Interestingly, basal level of ROS was also inhibited by TO in HepG2 cells. TO significantly inhibited PA-stimulated expressions of gluconeogenic genes. Finally, we found that anti-oxidative genes, such as Nrf2, were up-regulated after LXRs activation by TO. These results strongly support the notion that activation of LXRs is critical in suppression of liver gluconeogenesis and improvement of insulin sensitivity in diabetic individuals. At molecular levels, the mode of action appears to be as fellows: under diabetic condition, ROS production is increased, JNK is activated, and Akt activity is inhibited; TO-mediated LXR activation potently inhibits ROS production, increases anti-oxidative gene expressions, suppresses JNK activation, and restores Akt activity. Our data provide new evidence to support LXRs as promising therapeutic targets for anti-diabetic drug development. PMID:25909991

  9. Discovery of G Protein-Biased EP2 Receptor Agonists.

    PubMed

    Ogawa, Seiji; Watanabe, Toshihide; Sugimoto, Isamu; Moriyuki, Kazumi; Goto, Yoshikazu; Yamane, Shinsaku; Watanabe, Akio; Tsuboi, Kazuma; Kinoshita, Atsushi; Kigoshi, Hideo; Tani, Kousuke; Maruyama, Toru

    2016-03-10

    To identify G protein-biased and highly subtype-selective EP2 receptor agonists, a series of bicyclic prostaglandin analogues were designed and synthesized. Structural hybridization of EP2/4 dual agonist 5 and prostacyclin analogue 6, followed by simplification of the ω chain enabled us to discover novel EP2 agonists with a unique prostacyclin-like scaffold. Further optimization of the ω chain was performed to improve EP2 agonist activity and subtype selectivity. Phenoxy derivative 18a showed potent agonist activity and excellent subtype selectivity. Furthermore, a series of compounds were identified as G protein-biased EP2 receptor agonists. These are the first examples of biased ligands of prostanoid receptors. PMID:26985320

  10. Negative regulation of human fibrinogen gene expression by peroxisome proliferator-activated receptor alpha agonists via inhibition of CCAAT box/enhancer-binding protein beta.

    PubMed

    Gervois, P; Vu-Dac, N; Kleemann, R; Kockx, M; Dubois, G; Laine, B; Kosykh, V; Fruchart, J C; Kooistra, T; Staels, B

    2001-09-01

    Fibrinogen is a coagulation factor and an acute phase reactant up-regulated by inflammatory cytokines, such as interleukin 6 (IL-6). Elevated plasma fibrinogen levels are associated with coronary heart diseases. Fibrates are clinically used hypolipidemic drugs that act via the nuclear receptor peroxisome proliferator-activated receptor alpha (PPAR alpha). In addition, most fibrates also reduce plasma fibrinogen levels, but the molecular mechanism is unknown. In this study, we demonstrate that fibrates decrease basal and IL-6-stimulated expression of the human fibrinogen-beta gene in human primary hepatocytes and hepatoma HepG2 cells. Fibrates diminish basal and IL-6-induced fibrinogen-beta promoter activity, and this effect is enhanced in the presence of co-transfected PPAR alpha. Site-directed mutagenesis experiments demonstrate that PPAR alpha activators decrease human fibrinogen-beta promoter activity via the CCAAT box/enhancer-binding protein (C/EBP) response element. Co-transfection of the transcriptional intermediary factor glucocorticoid receptor-interacting protein 1/transcriptional intermediary factor 2 (GRIP1/TIF2) enhances fibrinogen-beta gene transcription and alleviates the repressive effect of PPAR alpha. Co-immunoprecipitation experiments demonstrate that PPAR alpha and GRIP1/TIF2 physically interact in vivo in human liver. These data demonstrate that PPAR alpha agonists repress human fibrinogen gene expression by interference with the C/EBP beta pathway through titration of the coactivator GRIP1/TIF2. We observed that the anti-inflammatory action of PPAR alpha is not restricted to fibrinogen but also applies to other acute phase genes containing a C/EBP response element; it also occurs under conditions in which the stimulating action of IL-6 is potentiated by dexamethasone. These findings identify a novel molecular mechanism of negative gene regulation by PPAR alpha and reveal the direct implication of PPAR alpha in the modulation of the inflammatory gene response in the liver. PMID:11418615

  11. Ombuin-3-O-β-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors α and δ/β

    SciTech Connect

    Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao; Lee, Ji Hae; Jun, Hee Jin; Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 ; Lee, Dong-Ho; Lee, Hak Ju; Lee, Chul; Lee, Myung Koo; Hwang, Bang Yeon; Lee, Sung-Joon; Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713

    2013-01-25

    Highlights: ► Ombuin-3-O-β-D-glucopyranoside is a dual ligand for PPARα and δ/β. ► Ombuin-3-O-β-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ► Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ► Cells stimulated with ombuine regulated target fatty acid β-oxidation and synthesis. ► Ombuin-3-O-β-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-β-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) α and δ/β. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPARα and δ/β but not to PPARγ or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPARα and δ/β. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPARα stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPARα and δ/β with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages.

  12. Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone reverses the adverse effects of diet-induced obesity on oocyte quality.

    PubMed

    Minge, Cadence E; Bennett, Brenton D; Norman, Robert J; Robker, Rebecca L

    2008-05-01

    Obesity and its physiological consequences are increasingly prevalent among women of reproductive age and are associated with infertility. To investigate, female mice were fed a high-fat diet until the onset of insulin resistance, followed by assessments of ovarian gene expression, ovulation, fertilization, and oocyte developmental competence. We report defects to ovarian function associated with diet-induced obesity (DIO) that result in poor oocyte quality, subsequently reduced blastocyst survival rates, and abnormal embryonic cellular differentiation. To identify critical cellular mediators of ovarian responses to obesity induced insulin resistance, DIO females were treated for 4 d before mating with an insulin-sensitizing pharmaceutical: glucose and lipid-lowering AMP kinase activator, 5-aminoimidazole 4-carboxamide-riboside, 30 mg/kg.d; sodium salicylate, IkappaK inhibitor that reverses insulin resistance, 50 mg/kg.d; or peroxisome proliferator activated receptor-gamma agonist rosiglitazone, 10 mg/kg.d. 5-aminoimidazole 4-carboxamide-riboside or sodium salicylate treatment did not have significant effects on the reproductive parameters examined. However, embryonic development to the blastocyst stage was significantly improved when DIO mice were treated with rosiglitazone, effectively repairing development rates. Rosiglitazone also normalized DIO-associated abnormal blastomere allocation to the inner cell mass. Such improvements to oocyte quality were coupled with weight loss, improved glucose metabolism, and changes in ovarian mRNA expression of peroxisome proliferator activated receptor-regulated genes, Cd36, Scarb1, and Fabp4 cholesterol transporters. These studies demonstrate that peri-conception treatment with select insulin-sensitizing pharmaceuticals can directly influence ovarian functions and ultimately exert positive effects on oocyte developmental competence. Improved blastocyst quality in obese females treated with rosiglitazone before mating indicates that peroxisome proliferator activated receptor-gamma is a key target for metabolic regulation of ovarian function and oocyte quality. PMID:18276752

  13. Orally active opioid μ/δ dual agonist MGM-16, a derivative of the indole alkaloid mitragynine, exhibits potent antiallodynic effect on neuropathic pain in mice.

    PubMed

    Matsumoto, Kenjiro; Narita, Minoru; Muramatsu, Naotaka; Nakayama, Terumi; Misawa, Kaori; Kitajima, Mariko; Tashima, Kimihito; Devi, Lakshmi A; Suzuki, Tsutomu; Takayama, Hiromitsu; Horie, Syunji

    2014-03-01

    (E)-Methyl 2-((2S,3S,7aS,12bS)-3-ethyl-7a-hydroxy-8-methoxy-1,2,3,4,6,7,7a,12b-octahydroindolo[2,3-a]quinolizin-2-yl)-3-methoxyacrylate (7-hydroxymitragynine), a main active constituent of the traditional herbal medicine Mitragyna speciosa, is an indole alkaloid that is structurally different from morphine. 7-Hydroxymitragynine induces a potent antinociceptive effect on mouse acute pain through μ-opioid receptors. In this study, we developed dual-acting μ- and δ-opioid agonists MGM-15 and MGM-16 from 7-hydroxymitragynine for the treatment of acute and chronic pain. MGM-16 showed a higher potency than that of 7-hydroxymitragynine and MGM-15 in in vitro and in vivo assays. MGM-16 exhibited a high affinity for μ- and δ-opioid receptors, with K(i) values of 2.1 and 7.0 nM, respectively. MGM-16 showed μ- and δ-opioid full agonistic effects in a guanosine 5'-O-(3-[(35)S]thiotriphosphate) binding assay and in a functional test using electrically elicited guinea pig ileum and mouse vas deferens contractions. Systemic administration of MGM-16 produced antinociceptive effects in a mouse acute pain model and antiallodynic effects in a chronic pain model. The antinociceptive effect of MGM-16 was approximately 240 times more potent than that of morphine in a mouse tail-flick test, and its antiallodynic effect was approximately 100 times more potent than that of gabapentin in partial sciatic nerve-ligated mice, especially with oral administration. The antinociceptive effect of MGM-16 was completely and partially blocked by the μ-selective antagonist β-funaltrexamine hydrochloride (β-FNA) and by the δ-selective antagonist naltrindole, respectively, in a tail-flick test. The antiallodynic effect of MGM-16 was completely blocked by β-FNA and naltrindole in a neuropathic pain model. These findings suggest that MGM-16 could become a class of a compound with potential therapeutic utility for treating neuropathic pain. PMID:24345467

  14. Effect of combination treatment of S–amlodipine with peroxisome proliferator-activated receptor agonists on metabolic and cardiovascular parameters in Zucker fa/fa rats

    PubMed Central

    2014-01-01

    Background Type 2 diabetes is a complex metabolic disorder characterized by hyperglycemia, impaired glucose tolerance and insulin resistance associated with dyslipidemia and hypertension. The available drugs are not sufficiently efficacious in reducing cardiovascular risk and restoring normal glucose metabolism associated with type 2 diabetes as a mono- or a combination therapy. The present study examined the combined effects of an antihypertensive (S-Amlodipine) and an insulin-sensitizing agent, peroxisome proliferator-activated receptor (PPAR) agonists (Pioglitazone and Ragaglitazar), on cardiovascular risk factors in aged diabetic and insulin-resistant Zucker fa/fa rats. Methods Following combination treatment for 14 days, blood pressure (BP), serum glucose, total cholesterol and triglycerides were measured. Aortic ring study was conducted to determine the effect of combination treatments on phenylephrine-induced vasoconstriction and acetylcholine (Ach)-induced vasorelaxation. Results In combination, S-Amlodipine and Pioglitazone significantly reduced blood glucose (115.1 ± 6.6 vs. 81.7 ± 4.2), BP (184.4 ± 5.0 vs. 155.1 ± 5.0), serum triglycerides (362.5 ± 47.5 vs. 211.1 ± 23.7) and glucose intolerance when compared with vehicle treated Zucker fa/fa rats. Similar results were observed with the combination of S-Amlodipine and Ragaglitazar (Triglycerides, 362.5 ± 47.5 vs. 252.34 ± 27.86; BP, 184.4 ± 5.0 vs. 159.0 ± 8.0) except for serum glucose. ACh-induced vasorelaxation in aortic rings was also superior with both of the combinations compared to individual treatment. Furthermore, there was less body weight gain and food intake with S-Amlodipine and Pioglitazone combination in Zucker fa/fa rats. S-Amlodipine itself caused significant reduction in glucose (115.1 ± 6.6 vs. 89.7 ± 2.7) and BP (184.4 ± 5.0 vs. 156.1 ± 4.0) with improvement in insulin sensitivity observed through oral glucose tolerance test. Conclusions The results suggest that a combination of PPAR agonists and S-Amlodipine has partial benefits in improving the cardiovascular risk factors such as reduction in triglyceride levels, associated with chronic type 2 diabetes, and therefore may be utilized as an approach for addressing some of these devastating metabolic syndrome complications. PMID:24673913

  15. Novel antipsychotic agents with 5-HT(1A) agonist properties: role of 5-HT(1A) receptor activation in attenuation of catalepsy induction in rats.

    PubMed

    Kleven, Mark S; Barret-Grévoz, Catherine; Bruins Slot, Liesbeth; Newman-Tancredi, Adrian

    2005-08-01

    Compounds possessing 5-HT(1A) agonist properties attenuate catalepsy induced by D(2) receptor blockade. Here we examined the role of 5-HT(1A) receptor agonism in the reduced cataleptogenic potential of several novel antipsychotic agents in the crossed leg position (CLP) and the bar catalepsy tests in rats. When administered alone, ziprasidone produced marked catalepsy, whereas aripiprazole, bifeprunox, SLV313, SSR181507 and sarizotan did not. However, when 5-HT(1A) receptors were blocked with the selective antagonist, WAY100635 (0.63 mg/kg, SC), robust cataleptogenic properties of SLV313, bifeprunox and sarizotan were unmasked and the catalepsy induced by ziprasidone was accentuated. In contrast, only modest catalepsy was induced by aripiprazole and SSR181507, even following a higher dose of WAY100635 (2.5 mg/kg). This suggests that these compounds possess other anti-cataleptic properties, such as partial agonism at dopamine D(2) receptors. The capacity to reverse neuroleptic-induced catalepsy was investigated in interaction studies with haloperidol (2.5 mg/kg, SC). Whereas ziprasidone and aripiprazole did not markedly reduce the effects of haloperidol, SLV313 and sarizotan attenuated CLP catalepsy. In contrast, SSR181507 and bifeprunox potently inhibited both CLP and bar catalepsy. Taken together, these data show that 5-HT(1A) receptor activation reduces the cataleptogenic potential of novel antipsychotic agents but indicate marked diversity in the contribution of 5-HT(1A) and/or other mechanisms to the profiles of the drugs. PMID:15996562

  16. Self-Assembly of the Toll-Like Receptor Agonist Macrophage-Activating Lipopeptide MALP-2 and of Its Constituent Peptide.

    PubMed

    Castelletto, Valeria; Kirkham, Steven; Hamley, Ian W; Kowalczyk, Radoslaw; Rabe, Martin; Reza, Mehedi; Ruokolainen, Janne

    2016-02-01

    The self-assembly of the macrophage-activating lipopeptide MALP-2 in aqueous solution has been investigated and is compared to that of the constituent peptide GNNDESNISFKEK. MALP-2 is a toll-like receptor agonist lipopeptide with diverse potential biomedical applications and its self-assembly has not previously been examined. It is found to self-assemble, above a critical aggregation concentration (cac), into remarkable "fibre raft" structures, based on lateral aggregation of β-sheet based bilayer tapes. Peptide GNNDESNISFKEK also forms β-sheet structures above a cac, although the morphology is distinct, comprising highly extended and twisted tape structures. A detailed insight into the molecular packing within the MALP-2 raft and GNNDESNISFKEK nanotape structures is obtained through X-ray diffraction and small-angle X-ray scattering. These results point to the significant influence of the attached lipid chains on the self-assembly motif, which lead to the raft structure for the lipopeptide assemblies. PMID:26752598

  17. Administration of the peroxisomal proliferator-activated receptor {gamma} agonist pioglitazone during fractionated brain irradiation prevents radiation-induced cognitive impairment

    SciTech Connect

    Zhao Weiling; Payne, Valerie; Tommasi, Ellen; Diz, Debra I.; Hsu, F.-C.; Robbins, Mike E. . E-mail: mrobbins@wfubmc.edu

    2007-01-01

    Purpose: We hypothesized that administration of the anti-inflammatory peroxisomal proliferator-activated receptor {gamma} (PPAR{gamma}) agonist pioglitazone (Pio) to adult male rats would inhibit radiation-induced cognitive impairment. Methods and Materials: Young adult male F344 rats received one of the following: (1) fractionated whole brain irradiation (WBI); 40 or 45 Gy {gamma}-rays in 4 or 4.5 weeks, respectively, two fractions per week and normal diet; (2) sham-irradiation and normal diet; (3) WBI plus Pio (120 ppm) before, during, and for 4 or 54 weeks postirradiation; (4) sham-irradiation plus Pio; or (5) WBI plus Pio starting 24h after completion of WBI. Results: Administration of Pio before, during, and for 4 or 54 weeks after WBI prevented Radiation-induced cognitive impairment. Administration of Pio for 54 weeks starting after completion of fractionated WBI substantially but not significantly reduced Radiation-induced cognitive impairment. Conclusions: These findings offer the promise of improving the quality of life and increasing the therapeutic window for brain tumor patients.

  18. Rosiglitazone, a Peroxisome Proliferator-Activated Receptor-γ Agonist, Restores Alveolar and Pulmonary Vascular Development in a Rat Model of Bronchopulmonary Dysplasia

    PubMed Central

    Lee, Hyun Ju; Lee, Youn Jin; Lee, Jin-A; Kim, Ee-Kyung; Kim, Han-Suk; Kim, Beyong Il; Choi, Jung-Hwan

    2014-01-01

    Purpose We tested whether rosiglitazone (RGZ), a peroxisome proliferator-activated receptor-γ agonist, can restore alveolar development and vascular growth in a rat model of bronchopulmonary dysplasia (BPD). Materials and Methods A rat model of BPD was induced through intra-amniotic delivery of lipopolysaccharide (LPS) and postnatal hyperoxia (80% for 7 days). RGZ (3 mg/kg/d, i.p.) or vehicle was given daily to rat pups for 14 days. This model included four experimental groups: No BPD+vehicle (V), No BPD+RGZ, BPD+V, and BPD+RGZ. On D14, alveolarization, lung vascular density, and right ventricular hypertrophy (RVH) were evaluated. Results Morphometric analysis revealed that the BPD+RGZ group had significantly smaller and more complex airspaces and larger alveolar surface area than the BPD+V group. The BPD+RGZ group had significantly greater pulmonary vascular density than the BPD+V group. Western blot analysis revealed that significantly decreased levels of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 by the combined exposure to intra-amniotic LPS and postnatal hyperoxia were restored by the RGZ treatment. RVH was significantly lesser in the BPD+RGZ group than in the BPD+V group. Conclusion These results suggest that RGZ can restore alveolar and pulmonary vascular development and lessen pulmonary hypertension in a rat model of BPD. PMID:24339293

  19. [Melatonin receptor agonist].

    PubMed

    Uchiyama, Makoto

    2015-06-01

    Melatonin is a hormone secreted by the pineal gland and is involved in the regulation of human sleep-wake cycle and circadian rhythms. The melatonin MT1 and MT2 receptors located in the suprachiasmatic nucleus in the hypothalamus play a pivotal role in the sleep-wake regulation. Based on the fact that MT1 receptors are involved in human sleep onset process, melatonin receptor agonists have been developed to treat insomnia. In this article, we first reviewed functions of melatonin receptors with special reference to MT1 and MT2, and properties and clinical application of melatonin receptor agonists as hypnotics. PMID:26065135

  20. Methyl substitution of 2-aminobicyclo[3.1.0]hexane 2,6-dicarboxylate (LY354740) determines functional activity at metabotropic glutamate receptors: identification of a subtype selective mGlu2 receptor agonist.

    PubMed

    Dominguez, Carmen; Prieto, Lourdes; Valli, Matthew J; Massey, Steven M; Bures, Mark; Wright, Rebecca A; Johnson, Bryan G; Andis, Sherri L; Kingston, Ann; Schoepp, Darryle D; Monn, James A

    2005-05-19

    LY354740 (1) is a highly potent and selective agonist of metabotropic glutamate (mGlu) receptors 2 and 3. In the present study, we have prepared C3- and C4-methyl-substituted variants of rac-1, compounds 5, 9, and 13. Each of these racemic methyl-substituted analogues displaced specific binding of the mGlu2/3 receptor antagonist (3)H-2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3-(xanth-9-yl)propanoic acid ((3)H-LY341495) from membranes expressing mGlu2 or mGlu3 receptor subtypes. Evaluation of the functional effects of this series on second messenger responses in cells expressing human mGlu2 or mGlu3 receptors revealed C3beta-methyl analogue 5 to possess antagonist properties at both mGlu2 and mGlu3 receptors while C4beta-methyl analogue 9 acts as a full agonist at each of these targets. Unexpectedly, we found that incorporation of a methyl substituent at the C4alpha-position as in analogue 13 results in a mixed mGlu2 agonist/mGlu3 antagonist pharmacological profile. All of the mGlu2 agonist and mGlu3 antagonist activity of rac-13 was found to reside in its resolved (+)-isomer. PMID:15887967

  1. Total Synthesis and Structure-Activity Relationship Study of the Potent cAMP Signaling Agonist (-)-Alotaketal A

    PubMed Central

    Huang, Jinhua; Yang, Jessica R.

    2013-01-01

    A detailed account of the first total synthesis of alotaketal A, a tricyclic spiroketal sesterterpenoid that potently activates the cAMP signaling pathway, is provided. The synthesis employs both intra- and intermolecular reductive allylation of esters for assembling one of the fragments and their coupling. A Hg(OAc)2-mediated allylic mercuration is used to introduce the C22-hydroxyl group. The subtle influence of substituents over the course of the spiroketalization process is revealed. The synthesis confirms the relative and absolute stereochemistry of (-)-alotaketal A and allows verification of alotaketal A’s effect over cAMP signaling using reporter-based FRET imaging assays with HEK 293T cells. Our studies also revealed alotaketal A’s unique activity in selectively targeting nuclear PKA signaling in living cells. PMID:23584129

  2. Indole Glucocorticoid Receptor Antagonists Active in a Model of Dyslipidemia Act via a Unique Association with an Agonist Binding Site.

    PubMed

    Luz, John G; Carson, Matthew W; Condon, Bradley; Clawson, David; Pustilnik, Anna; Kohlman, Daniel T; Barr, Robert J; Bean, James S; Dill, M Joelle; Sindelar, Dana K; Maletic, Milan; Coghlan, Michael J

    2015-08-27

    To further elucidate the structural activity correlation of glucocorticoid receptor (GR) antagonism, the crystal structure of the GR ligand-binding domain (GR LBD) complex with a nonsteroidal antagonist, compound 8, was determined. This novel indole sulfonamide shows in vitro activity comparable to known GR antagonists such as mifepristone, and notably, this molecule lowers LDL (-74%) and raises HDL (+73%) in a hamster model of dyslipidemia. This is the first reported crystal structure of the GR LBD bound to a nonsteroidal antagonist, and this article provides additional elements for the design and pharmacology of clinically relevant nonsteroidal GR antagonists that may have greater selectivity and fewer side effects than their steroidal counterparts. PMID:26218343

  3. Design and evaluation of novel biphenyl sulfonamide derivatives with potent histamine H(3) receptor inverse agonist activity.

    PubMed

    Covel, Jonathan A; Santora, Vincent J; Smith, Jeffrey M; Hayashi, Rena; Gallardo, Charlemagne; Weinhouse, Michael I; Ibarra, Jason B; Schultz, Jeffrey A; Park, Douglas M; Estrada, Scott A; Hofilena, Brian J; Pulley, Michelle D; Smith, Brian M; Ren, Albert; Suarez, Marissa; Frazer, John; Edwards, Jeffrey; Hauser, Erin K; Lorea, Jodie; Semple, Graeme; Grottick, Andrew J

    2009-09-24

    Antagonism of the histamine-H(3) receptor is one tactic being explored to increase wakefulness for the treatment of disorders such as excessive daytime sleepiness (EDS) as well as other sleep or cognitive disorders. Phenethyl-R-2-methylpyrrolidine containing biphenylsulfonamide compounds were shown to be potent and selective antagonists of the H(3) receptor. Several of these compounds demonstrated in vivo activity in a rat model of (R)-alpha-methyl histamine (RAMH) induced dipsogenia, and one compound (4e) provided an increase in wakefulness in rats as measured by polysomnographic methods. However, more detailed analysis of the PK/PD relationship suggested the presence of a common active metabolite which may preclude this series of compounds from further development. PMID:19722526

  4. Lesions of area postrema and subfornical organ alter exendin-4-induced brain activation without preventing the hypophagic effect of the GLP-1 receptor agonist.

    PubMed

    Baraboi, Elena-Dana; Smith, Pauline; Ferguson, Alastair V; Richard, Denis

    2010-04-01

    The mechanism and route whereby glucagon-like peptide 1 (GLP-1) receptor agonists, such as GLP-1 and exendin-4 (Ex-4), access the central nervous system (CNS) to exert their metabolic effects have yet to be clarified. The primary objective of the present study was to investigate the potential role of two circumventricular organs (CVOs), the area postrema (AP) and the subfornical organ (SFO), in mediating the metabolic and CNS-stimulating effects of Ex-4. We demonstrated that electrolytic ablation of the AP, SFO, or AP + SFO does not acutely prevent the anorectic effects of Ex-4. AP + SFO lesion chronically decreased food intake and body weight and also modulated the effect of Ex-4 on the neuronal activation of brain structures involved in the hypothalamic-pituitary-adrenal axis and glucose metabolism. The results of the study also showed that CVO lesions blunted Ex-4-induced expression of c-fos mRNA (a widely used neuronal activity marker) in 1) limbic structures (bed nucleus of the stria terminalis and central amygdala), 2) hypothalamus (paraventricular hypothalamic nucleus, supraoptic nucleus, and arcuate nucleus), and 3) hindbrain (lateral and lateral-external parabrachial nucleus, medial nucleus of the solitary tract, and ventrolateral medulla). In conclusion, although the present results do not support a role for the CVOs in the anorectic effect induced by a single injection of Ex-4, they suggest that the CVOs play important roles in mediating the actions of Ex-4 in the activation of CNS structures involved in homeostatic control. PMID:20106992

  5. Immunosuppressive activity of FTY720, sphingosine 1-phosphate receptor agonist: I. Prevention of allograft rejection in rats and dogs by FTY720 and FTY720-phosphate.

    PubMed

    Chiba, K; Hoshino, Y; Ohtsuki, M; Kataoka, H; Maeda, Y; Matsuyuki, H; Sugahara, K; Kiuchi, M; Hirose, R; Adachi, K

    2005-01-01

    FTY720, a new class of immunomodulator, induces lymphopenia by sequestration of circulating lymphocytes into secondary lymphoid tissues. FTY720 at 0.1 to 1 mg/kg significantly prolonged the allograft survival in a dose-dependent manner and showed a marked synergistic effect in combination with cyclosporine (CsA) in rat skin and cardiac allograft models. In addition, the canine renal allograft survival was significantly prolonged by combination therapy with FTY720 at 0.03 to 1 mg/kg and CsA at 10 mg/kg as compared with monotherapy of FTY720 or CsA. By contrast, the combination therapy with CsA and azathioprine or CsA and mycophenolate mofetil resulted in only an additive effect in rat skin allograft. When FTY720 was administered to rats, FTY720 was metabolized by omega-oxidation of the octyl side chain, and beta-oxidation subsequently, or phosphorylated by sphingosine kinase. Omega- and beta-oxidized 4 metabolities of FTY720 at 10 mg/kg i.v. showed neither lymphopenia nor immunosuppressive activity in rat skin allograft. On the other hand, (S)-enantiomer of FTY720-phosphate at 0.1 and 1 mg/kg intravenously induced a marked lymphopenia and significantly prolonged the allograft survival in the rat allotransplantation. From these results, it is suggested the lymphopenia and the immunosuppression induced by FTY720 administration is due to the agonistic activity against SIP receptors of the active metabolite, (S)-FTY720-phosphate. PMID:15808561

  6. The Dectin 1 Agonist Curdlan Regulates Osteoclastogenesis by Inhibiting Nuclear Factor of Activated T cells Cytoplasmic 1 (NFATc1) through Syk Kinase

    PubMed Central

    Yamasaki, Toru; Ariyoshi, Wataru; Okinaga, Toshinori; Adachi, Yoshiyuki; Hosokawa, Ryuji; Mochizuki, Shinichi; Sakurai, Kazuo; Nishihara, Tatsuji

    2014-01-01

    Several immune system cell surface receptors are reported to be associated with osteoclastogenesis. Dectin 1, a lectin receptor for β-glucan, is found predominantly on cells of the myeloid lineage. In this study, we examined the effect of the dectin 1 agonist curdlan on osteoclastogenesis. In mouse bone marrow cells and dectin 1-overexpressing RAW 264.7 cells (d-RAWs), curdlan suppressed receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation, bone resorption, and actin ring formation in a dose-dependent manner. This was achieved within non-growth inhibitory concentrations at the early stage. Conversely, curdlan had no effect on macrophage colony-stimulating factor-induced differentiation. Furthermore, curdlan inhibited RANKL-induced nuclear factor of activated T cell cytoplasmic 1 (NFATc1) expression, thereby decreasing osteoclastogenesis-related marker gene expression, including tartrate-resistant acid phosphatase, osteoclast stimulatory transmembrane protein, cathepsin K, and matrix metallopeptidase 9. Curdlan inhibited RANKL-induced c-fos expression, followed by suppression of NFATc1 autoamplification, without significantly affecting the NF-κB signaling pathway. We also observed that curdlan treatment decreased Syk protein in d-RAWs. Inhibition of the dectin 1-Syk kinase pathway by Syk-specific siRNA or chemical inhibitors suppressed osteoclast formation and NFATc1 expression stimulated by RANKL. In conclusion, our results demonstrate that curdlan potentially inhibits osteoclast differentiation, especially NFATc1 expression, and that Syk kinase plays a crucial role in the transcriptional pathways. This suggests that the activation of dectin 1-Syk kinase interaction critically regulates the genes required for osteoclastogenesis. PMID:24821724

  7. DSP-1053, a novel serotonin reuptake inhibitor with 5-HT1A partial agonistic activity, displays fast antidepressant effect with minimal undesirable effects in juvenile rats

    PubMed Central

    Kato, Taro; Matsumoto, Yuji; Yamamoto, Masanori; Matsumoto, Kenji; Baba, Satoko; Nakamichi, Keiko; Matsuda, Harumi; Nishimuta, Haruka; Yabuuchi, Kazuki

    2015-01-01

    Enhancement of serotonergic neurotransmission has been the main stream of treatment for patients with depression. However, delayed therapeutic onset and undesirable side effects are major drawbacks for conventional serotonin reuptake inhibitors. Here, we show that DSP-1053, a novel serotonin reuptake inhibitor with 5-HT1A partial agonistic activity, displays fast antidepressant efficacy with minimal undesirable effects, especially nausea and emesis in animal models. DSP-1053 bound human serotonin transporter and 5-HT1A receptor with the Ki values of 1.02 ± 0.06 and 5.05 ± 1.07 nmol/L, respectively. This compound inhibited the serotonin transporter with an IC50 value of 2.74 ± 0.41 nmol/L and had an intrinsic activity for 5-HT1A receptors of 70.0 ± 6.3%. In rat microdialysis, DSP-1053, given once at 3 and 10 mg kg−1, dose-dependently increased extracellular 5-HT levels. In the rat forced swimming test, 2-week administration of DSR-1053 (1 mg kg−1) significantly reduced rats immobility time after treatment, whereas paroxetine (3 and 10 mg kg−1) required 3-week administration to reduce rats immobility time. In olfactory bulbectomy model, 1- and 2-week administration of DSP-1053 reduced both of emotional scores and activity in the open field, whereas paroxetine required 2 weeks to show similar beneficial effects. Although single administration of DSP-1053-induced emesis and vomiting in the rat and Suncus murinus, multiple treatment with this compound, but not with paroxetine, decreased the number of vomiting episodes. These results highlight the important role of 5-HT1A receptors in both the efficacy and tolerability of DSP-1053 as a new therapeutic option for the treatment of depression. PMID:26171224

  8. Analgesic activity and pharmacological characterization of N-[1-phenylpyrazol-3-yl]-N-[1-(2-phenethyl)-4-piperidyl] propenamide, a new opioid agonist acting peripherally.

    PubMed

    Goicoechea, Carlos; Sánchez, Eva; Cano, Carolina; Jagerovic, Nadine; Martín, Maria Isabel

    2008-10-24

    We previously reported the synthesis of three new opioid agonists as well as their in vitro and in vivo activity [Girón, R., Abalo, R., Goicoechea, C., Martín, M.I., Callado, L.F., Cano, C., Goya, P., Jagerovic, N. 2002. Synthesis and opioid activity of new fentanyl analogs. Life Sci. 71, 1023-1034]. One of them, N-[1-phenylpyrazol-3-yl]-N-[1-(2-phenethyl)-4-piperidyl)] propenamide (IQMF-4), showed an interesting antinociceptive activity. Intraperitoneally (i.p.) administered, it was as effective as fentanyl or morphine, being less potent than fentanyl but more so than morphine. The aim of the present work was to evaluate its antinociceptive effect by different routes of administration, using the hot plate test, and to investigate possible side effects, such as tolerance and withdrawal, in vitro, using the myenteric plexus-longitudinal muscle strip preparation from guinea pig ileum, and in vivo, using the hot plate test. IQMF-4 was more potent than morphine when administered per os (p.o.), but less potent when administered intracerebroventricularly (i.c.v.). By both routes, fentanyl is more potent that IQMF-4. When IQMF-4 was administered i.p., naloxone methiodide, a peripherally acting antagonist, was able to completely block its antinociceptive effect, whereas, after i.c.v. administration, the blockade was only partial. An interesting feature of the new compound is that it induces tolerance in vitro but not in vivo. Moreover, though in vitro withdrawal was not different from fentanyl or morphine, in vivo withdrawal symptoms were significantly less frequent in mice treated with IQMF-4 than in those treated with morphine or fentanyl. Although more assays are required, these results show that IQMF-4 appears to be a potent analgesic compound with an interesting peripheral component, and reduced ability to induce dependence. PMID:18706410

  9. TLR2 agonist PSK activates human NK cells and enhances the anti-tumor effect of HER2-targeted monoclonal antibody therapy

    PubMed Central

    Lu, Hailing; Yang, Yi; Gad, Ekram; Inatsuka, Carol; Wenner, Cynthia A.; Disis, Mary L.; Standish, Leanna J.

    2011-01-01

    Purpose The therapeutic effect of trastuzumab monoclonal antibody (mAb) therapy has been shown to be partially dependent on functional NK cells. Novel agents that enhance NK cell function could potentially improve the anti-tumor effect of trastuzumab. We recently identified polysaccharide krestin (PSK), a natural product extracted from medicinal mushroom Trametes Versicolor, as a potent TLR2 agonist. The current study was undertaken to evaluate the effect of PSK on human NK cells and the potential of using PSK to enhance HER2-targeted mAb therapy. Experimental Design Human PBMC were stimulated with PSK to evaluate the effect of PSK on NK cell activation, IFN-? production, cytotoxicity, and trastuzumab-mediated ADCC. Whether the effect of PSK on NK cells is direct or indirect was also investigated. Then in vivo experiment in neu transgenic mice was carried out to determine the potential of using PSK to augment the anti-tumor effect of HER2-targeted mAb therapy. Results PSK activated human NK cells to produce IFN-? and to lyse K562 target cells. PSK also enhanced trastuzumab-mediated ADCC against SKBR3 and MDA-MB-231 breast cancer cells. Both direct and IL-12-dependent indirect effects seem to be involved in the effect of PSK on NK cells. Oral administration of PSK significantly potentiated the anti-tumor effect of anti-HER2/neu mAb therapy in neu-transgenic mice. Conclusion These results demonstrated that PSK activates human NK cells and potentiates trastuzumab-mediated ADCC. Concurrent treatment of PSK and trastuzumab may be a novel way to augment the anti-tumor effect of trastuzumab. PMID:21918170

  10. Immunization of male rabbits with sheep luteal receptor to LH results in production of antibodies exhibiting hormone-agonistic and -antagonistic activities.

    PubMed

    Jeyakumar, M; Moudgal, N R

    1996-09-01

    Antibodies to LH/chorionic gonadotrophin receptor (LH/CG-R; molecular weight 67 000), isolated in a homogenous state (established by SDS-PAGE and ligand blotting) from sheep luteal membrane using human CG (hCG)-Sepharose affinity chromatography, were raised in three adult male rabbits (R-I, R-II and R-III). Each of the rabbits received 20-30 micrograms of the purified receptor in Freund's complete adjuvant at a time. Primary immunization was followed by booster injection at intervals. Production of receptor antibodies was monitored by (1) determining the dilution of the serum (IgG fraction) that could specifically bind 50% of 125I-LH/CG-R added and (2) analysing sera for any change in testosterone levels. Following primary immunization and the first booster, all three rabbits exhibited a 2.5- to 6.0-fold increase in serum testosterone over basal levels and this effect was spread over a period of time (approximately 40 days) coinciding with the rise and fall of receptor antibodies. The maximal antibody titre (ED50) produced at this time ranged from 1:350 to 1:100 to below detectable limits for R-I, R-II and R-III respectively. Subsequent immunizations followed by the second booster resulted in a substantial increase in antibody titre (ED50 of 1:5000) in R-I, but this was not accompanied by any change in serum testosterone over preimmune levels, suggesting that with the progress of immunization the character of the antibody produced had also changed. Two pools of antisera from R-I collected 10 days following the booster (at day 70 (bleed I) and day 290 (bleed II)) were used in further experiments. IgG isolated from bleed I but not from bleed II antiserum showed a dose-dependent stimulation of testosterone production by mouse Leydig cells in vitro, thus confirming the in vivo hormone-mimicking activity of antibodies generated during the early immunization phase. The IgG fractions from both bleeds were, however, capable of inhibiting (1) 125I-hCG binding to crude sheep luteal membrane (EC50 of 1:70 and 1:350 for bleed I and II antisera respectively) and (2) ovine LH-stimulated testosterone production by mouse Leydig cells in vitro, indicating the presence of antagonistic antibodies irrespective of the period of time during which the rabbits were immunized. The fact that bleed I-stimulated testosterone production could be inhibited in a dose-dependent manner by the addition of IgG from bleed II to the mouse Leydig cell in vitro assay system showed that the agonistic activity is intrinsic to the bleed I antibody. The receptor antibody (bleed II) was also capable of blocking LH action in vivo, as rabbits passively (for 24 h with LH/CG-R antiserum) as well as actively (for 430 days) immunized against LH/CG-R failed to respond to a bolus injection of LH (50 micrograms). At no time, however, was the serum testosterone reduced below the basal level. This study clearly shows that, unlike with LH antibody, attempts to achieve an LH deficiency effect in vivo by resorting to immunization with holo LH receptor is difficult, as receptor antibodies exhibit both hormone-mimicking (agonistic) as well as hormone-blocking (antagonistic) activities. PMID:8882162

  11. The cannabinoid receptor agonist THC attenuates weight loss in a rodent model of activity-based anorexia.

    PubMed

    Verty, Aaron N A; Evetts, Megan J; Crouch, Geraldine J; McGregor, Iain S; Stefanidis, Aneta; Oldfield, Brian J

    2011-06-01

    Anorexia nervosa (AN) is characterized by anhedonia whereby patients experience little pleasure or reward in many aspects of their lives. Reward pathways and the endocannabionid system have been implicated in the mediation of food intake. The potential to exploit these systems to reverse weight loss is investigated in a rodent model of activity-based anorexia (ABA). The effect of subchronic (6 days) Δ(9)-tetrahydrocannabinol (THC) treatment (0.1, 0.5, or 2.0 mg/kg/day) was assessed on chow and high-fat diet (HFD) intake, body weight, running wheel activity (RWA) as well as thermogenesis in brown adipose tissue (BAT) and lipid metabolism in white adipose tissue (WAT). Limited time availability of food and continuous access to running wheels led to anorexia and significantly reduced body weight. THC treatment (0.5 and 2.0 mg/kg/day) transiently stimulated chow intake with a moderate effect on RWA. THC (2.0 mg/kg/day) significantly reduced body weight loss and shifted markers of thermogenesis in BAT and lipid metabolism in WAT in directions consistent with reduced energy expenditure and lipolysis. THC (2.0 mg/kg/day) combined with HFD, produced a transient increase in food intake, reduction in RWA, attenuation of body weight loss, and changes in markers of thermogensis in BAT and lipolysis in the WAT. These changes were significantly greater than those seen in vehicle (HFD), vehicle (chow), and THC (chow)-treated animals. These data show for the first time the effectiveness of the endocannabinoid system in attenuating the weight loss associated with the development of ABA via a mechanism involving reduced energy expenditure. PMID:21412227

  12. On the Origin of Muscle Synergies: Invariant Balance in the Co-activation of Agonist and Antagonist Muscle Pairs

    PubMed Central

    Hirai, Hiroaki; Miyazaki, Fumio; Naritomi, Hiroaki; Koba, Keitaro; Oku, Takanori; Uno, Kanna; Uemura, Mitsunori; Nishi, Tomoki; Kageyama, Masayuki; Krebs, Hermano Igo

    2015-01-01

    Investigation of neural representation of movement planning has attracted the attention of neuroscientists, as it may reveal the sensorimotor transformation essential to motor control. The analysis of muscle synergies based on the activity of agonist–antagonist (AA) muscle pairs may provide insight into such transformations, especially for a reference frame in the muscle space. In this study, we examined the AA concept using the following explanatory variables: the AA ratio, which is related to the equilibrium-joint angle, and the AA sum, which is associated with joint stiffness. We formulated muscle synergies as a function of AA sums, positing that muscle synergies are composite units of mechanical impedance. The AA concept can be regarded as another form of the equilibrium-point (EP) hypothesis, and it can be extended to the concept of EP-based synergies. We introduce, here, a novel tool for analyzing the neurological and motor functions underlying human movements and review some initial insights from our results about the relationships between muscle synergies, endpoint stiffness, and virtual trajectories (time series of EP). Our results suggest that (1) muscle synergies reflect an invariant balance in the co-activation of AA muscle pairs; (2) each synergy represents the basis for the radial, tangential, and null movements of the virtual trajectory in the polar coordinates centered on the specific joint at the base of the body; and (3) the alteration of muscle synergies (for example, due to spasticity or rigidity following neurological injury) results in significant distortion of endpoint stiffness and concomitant virtual trajectories. These results indicate that muscle synergies (i.e., the balance of muscle mechanical impedance) are essential for motor control. PMID:26636079

  13. Detection of differentially regulated subsarcolemmal calcium signals activated by vasoactive agonists in rat pulmonary artery smooth muscle cells

    PubMed Central

    Subedi, Krishna P.; Paudel, Omkar

    2013-01-01

    Intracellular calcium (Ca2+) plays pivotal roles in distinct cellular functions through global and local signaling in various subcellular compartments, and subcellular Ca2+ signal is the key factor for independent regulation of different cellular functions. In vascular smooth muscle cells, subsarcolemmal Ca2+ is an important regulator of excitation-contraction coupling, and nucleoplasmic Ca2+ is crucial for excitation-transcription coupling. However, information on Ca2+ signals in these subcellular compartments is limited. To study the regulation of the subcellular Ca2+ signals, genetically encoded Ca2+ indicators (cameleon), D3cpv, targeting the plasma membrane (PM), cytoplasm, and nucleoplasm were transfected into rat pulmonary arterial smooth muscle cells (PASMCs) and Ca2+ signals were monitored using laser scanning confocal microscopy. In situ calibration showed that the Kd for Ca2+ of D3cpv was comparable in the cytoplasm and nucleoplasm, but it was slightly higher in the PM. Stimulation of digitonin-permeabilized cells with 1,4,5-trisphosphate (IP3) elicited a transient elevation of Ca2+ concentration with similar amplitude and kinetics in the nucleoplasm and cytoplasm. Activation of G protein-coupled receptors by endothelin-1 and angiotensin II preferentially elevated the subsarcolemmal Ca2+ signal with higher amplitude in the PM region than the nucleoplasm and cytoplasm. In contrast, the receptor tyrosine kinase activator, platelet-derived growth factor, elicited Ca2+ signals with similar amplitudes in all three regions, except that the rise-time and decay-time were slightly slower in the PM region. These data clearly revealed compartmentalization of Ca2+ signals in the subsarcolemmal regions and provide the basis for further investigations of differential regulation of subcellular Ca2+ signals in PASMCs. PMID:24352334

  14. Neuroprotective effects of peroxisome proliferator-activated receptor alpha and gamma agonists in model of parkinsonism induced by intranigral 1-methyl-4-phenyl-1,2,3,6-tetrahyropyridine.

    PubMed

    Barbiero, Janaína K; Santiago, Ronise M; Persike, Daniele Suzete; da Silva Fernandes, Maria José; Tonin, Fernanda S; da Cunha, Claudio; Lucio Boschen, Suelen; Lima, Marcelo M S; Vital, Maria A B F

    2014-11-01

    A large body of evidence suggests that peroxisome proliferator-activated receptor (PPAR) agonists may improve some of the pathological features of Parkinson's disease (PD). In the present study, we evaluated the effects of the PPAR-α agonist fenofibrate (100mg/kg) and PPAR-γ agonist pioglitazone (30mg/kg) in a rat model of parkinsonism induced by intranigral 1-methyl-4-phenyl-1,2,3,6-tetrahyropyridine (MPTP). Male Wistar rats were pretreated with both drugs for 5 days and received an infusion of MPTP. The experiments were divided into two parts. First, 1, 7, 14, and 21 days after surgery, the animals were submitted to the open field test. On days 21 and 22, the rats were subjected to the forced swim test and two-way active avoidance task. In the second part of the study, 24h after neurotoxin administration, immunohistochemistry was performed to assess tyrosine hydroxylase activity. The levels of dopamine and its metabolites in the striatum were determined using high-performance liquid chromatography, and fluorescence detection was used to assess caspase-3 activation in the substantia nigra pars compacta (SNpc). Both fenofibrate as pioglitazone protected against hypolocomotion, depressive-like behavior, impairment of learning and memory, and dopaminergic neurodegeneration caused by MPTP, with dopaminergic neuron loss of approximately 33%. Fenofibrate and pioglitazone also protected against the increased activation of caspase-3, an effector enzyme of the apoptosis cascade that is considered one of the pathological features of PD. Thus, PPAR agonists may contribute to therapeutic strategies in PD. PMID:25127682

  15. Anticancer activity of the type I insulin-like growth factor receptor antagonist, ganitumab, in combination with the death receptor 5 agonist, conatumumab

    PubMed Central

    Chawla, Sant P.; Kindler, Hedy; Reckamp, Karen; Chiorean, E. Gabriela; Azad, Nilofer S.; Lockhart, A. Craig; Hsu, Cheng-Pang; Baker, Nigel F.; Galimi, Francesco; Beltran, Pedro; Baselga, José

    2015-01-01

    Agents targeting the insulin-like growth factor receptor type 1 (IGF1R) have shown antitumor activity. Based on the evidence for interaction between the IGF-1 and TRAIL pathways, we hypothesized that the combination of ganitumab (monoclonal antibody to IGF1R) with the pro-apoptotic death receptor 5 agonist, conatumumab, might increase antitumor response. Ganitumab and conatumumab were tested in combination in a Colo-205 xenograft model. Part 1 of the clinical study was a phase Ib program of three doses of conatumumab (1, 3, 15 mg/kg) in combination with 18 mg/kg ganitumab to determine the maximum tolerated dose (MTD) in patients with advanced solid tumors. Part 2 was conducted in six cohorts with advanced non-small cell lung cancer (squamous or nonsquamous histology), colorectal cancer, sarcoma, pancreatic cancer, or ovarian cancer, treated at the recommended doses of the combination. The combination was significantly more active in the Colo-205 xenograft model than either single agent alone (p<0.0015). In part 1 of the clinical study, no dose-limiting toxicities were observed and the MTD of conatumumab was 15 mg/kg in combination with 18 mg/kg ganitumab. In part 2, 78 patients were treated and there were no objective responses but 28 patients (36 %) had stable disease (median 46 days, range 0–261). The combination was well-tolerated with no new toxicities. In conclusion, the combination of ganitumab and conatumumab was well-tolerated but had no objective responses in the population tested. The successful future application of this combination of antitumor mechanisms may rely on the identification of predictive biomarkers. PMID:24816908

  16. Anticancer activity of the type I insulin-like growth factor receptor antagonist, ganitumab, in combination with the death receptor 5 agonist, conatumumab.

    PubMed

    Tabernero, Josep; Chawla, Sant P; Kindler, Hedy; Reckamp, Karen; Chiorean, E Gabriela; Azad, Nilofer S; Lockhart, A Craig; Hsu, Cheng-Pang; Baker, Nigel F; Galimi, Francesco; Beltran, Pedro; Baselga, José

    2015-03-01

    Agents targeting the insulin-like growth factor receptor type 1 (IGF1R) have shown antitumor activity. Based on the evidence for interaction between the IGF-1 and TRAIL pathways, we hypothesized that the combination of ganitumab (monoclonal antibody to IGF1R) with the pro-apoptotic death receptor 5 agonist, conatumumab, might increase antitumor response. Ganitumab and conatumumab were tested in combination in a Colo-205 xenograft model. Part 1 of the clinical study was a phase Ib program of three doses of conatumumab (1, 3, 15 mg/kg) in combination with 18 mg/kg ganitumab to determine the maximum tolerated dose (MTD) in patients with advanced solid tumors. Part 2 was conducted in six cohorts with advanced non-small cell lung cancer (squamous or non-squamous histology), colorectal cancer, sarcoma, pancreatic cancer, or ovarian cancer, treated at the recommended doses of the combination. The combination was significantly more active in the Colo-205 xenograft model than either single agent alone (p < 0.0015). In part 1 of the clinical study, no dose-limiting toxicities were observed and the MTD of conatumumab was 15 mg/kg in combination with 18 mg/kg ganitumab. In part 2, 78 patients were treated and there were no objective responses but 28 patients (36 %) had stable disease (median 46 days, range 0-261). The combination was well-tolerated with no new toxicities. In conclusion, the combination of ganitumab and conatumumab was well-tolerated but had no objective responses in the population tested. The successful future application of this combination of antitumor mechanisms may rely on the identification of predictive biomarkers. PMID:24816908

  17. Clozapine Acts as an Agonist at Serotonin 2A Receptors to Counter MK-801-Induced Behaviors through a βArrestin2-Independent Activation of Akt

    PubMed Central

    Schmid, Cullen L; Streicher, John M; Meltzer, Herbert Y; Bohn, Laura M

    2014-01-01

    The G protein-coupled serotonin 2A receptor (5-HT2AR) is a prominent target for atypical antipsychotic drugs, such as clozapine. Although clozapine is known to inhibit 5-HT2AR signaling through G protein-dependent mechanisms, it differs from classic GPCR antagonists, in that it also induces 5-HT2AR internalization and activates Akt signaling via a 5-HT2AR-mediated event. In this regard, clozapine may also be considered a functionally selective agonist. The cognate neurotransmitter at the 5-HT2AR, serotonin, also induces 5-HT2AR internalization and Akt phosphorylation. Serotonin promotes interactions with the scaffolding and regulatory protein, βarrestin2, which results in the recruitment and activation of Akt. These interactions prove to be critical for serotonin-induced, 5-HT2AR-mediated behavioral responses in mice. Herein, we sought to determine whether clozapine also utilizes βarrestin2-mediated mechanisms to induce 5-HT2AR signaling, and whether this interaction contributes to its behavioral effects in mice. We demonstrate that unlike serotonin, clozapine-mediated 5-HT2AR internalization and Akt phosphorylation is independent of receptor interactions with βarrestin2. Moreover, clozapine-mediated suppression of MK-801 and phencyclidine (PCP)-induced hyperlocomotion is βarrestin2 independent, although it is dependent upon Akt. These results demonstrate that pharmacologically oppositional ligands, serotonin and clozapine, utilize differential mechanisms to achieve the same 5-HT2AR-meadiated downstream events: Akt phosphorylation and receptor internalization. Although βarrestin2 has no effect on clozapine's actions in vivo, Akt phosphorylation is required for clozapine's efficacy in blocking MK-801- and PCP-induced models of schizophrenic behaviors in mice. PMID:24531562

  18. Active-to-absorbing-state phase transition in the presence of fluctuating environments: weak and strong dynamic scaling.

    PubMed

    Sarkar, Niladri; Basu, Abhik

    2012-08-01

    We investigate the scaling properties of phase transitions between survival and extinction (active-to-absorbing-state phase transition, AAPT) in a model that by itself belongs to the directed percolation (DP) universality class, interacting with a spatiotemporally fluctuating environment having its own nontrivial dynamics. We model the environment by (i) a randomly stirred fluid, governed by the Navier-Stokes (NS) equation, and (ii) a fluctuating surface, described either by the Kardar-Parisi-Zhang (KPZ) or the Edward-Wilkinson (EW) equations. We show, by using a one-loop perturbative field theoretic setup that, depending upon the spatial scaling of the variance of the external forces that drive the environment (i.e., the NS, KPZ, or EW equations), the system may show weak or strong dynamic scaling at the critical point of active-to-absorbing-state phase transitions. In the former case AAPT displays scaling belonging to the DP universality class, whereas in the latter case the universal behavior is different. PMID:23005737

  19. Identification of Darmstoff analogs as selective agonists and antagonists of lysophosphatidic acid receptors.

    PubMed

    Gududuru, Veeresa; Zeng, Kui; Tsukahara, Ryoko; Makarova, Natalia; Fujiwara, Yuko; Pigg, Kathryn R; Baker, Daniel L; Tigyi, Gabor; Miller, Duane D

    2006-01-15

    Darmstoff describes a family of gut smooth muscle-stimulating acetal phosphatidic acids initially isolated and characterized from the bath fluid of stimulated gut over 50 years ago. Despite similar structural and biological profiles, Darmstoff analogs have not previously been examined as potential LPA mimetics. Here, we report a facile method for the synthesis of potassium salts of Darmstoff analogs. To understand the effect of stereochemistry on lysophosphatidic acid mimetic activity, synthesis of optically pure stereoisomers of selected Darmstoff analogs was achieved starting with chiral methyl glycerates. Each Darmstoff analog was evaluated for subtype-specific LPA receptor agonist/antagonist activity, PPARgamma activation, and autotaxin inhibition. From this study we identified compound 12 as a pan-antagonist and several pan-agonists for the LPA(1-3) receptors. Introduction of an aromatic ring in the lipid chain such as analog 22 produced a subtype-specific LPA(3) agonist with an EC(50) of 692 nM. Interestingly, regardless of their LPA(1/2/3) ligand properties all of the Darmstoff analogs tested activated PPARgamma. However, these compounds are weak inhibitors of autotaxin. The results indicate that Darmstoff analogs constitute a novel class of lysophosphatidic acid mimetics. PMID:16290140

  20. Vasculotide reduces endothelial permeability and tumor cell extravasation in the absence of binding to or agonistic activation of Tie2

    PubMed Central

    Wu, Florence TH; Lee, Christina R; Bogdanovic, Elena; Prodeus, Aaron; Gariépy, Jean; Kerbel, Robert S

    2015-01-01

    Angiopoietin-1 (Ang1) activation of Tie2 receptors on endothelial cells (ECs) reduces adhesion by tumor cells (TCs) and limits junctional permeability to TC diapedesis. We hypothesized that systemic therapy with Vasculotide (VT)—a purported Ang1 mimetic, Tie2 agonist—can reduce the extravasation of potentially metastatic circulating TCs by similarly stabilizing the host vasculature. In vitro, VT and Ang1 treatments impeded endothelial hypermeability and the transendothelial migration of MDA-MB-231•LM2-4 (breast), HT29 (colon), or SN12 (renal) cancer cells to varying degrees. In mice, VT treatment inhibited the transit of TCs through the pulmonary endothelium, but not the hepatic or lymphatic endothelium. In the in vivo LM2-4 model, VT monotherapy had no effect on primary tumors, but significantly delayed distant metastatic dissemination to the lungs. In the post-surgical adjuvant treatment setting, VT therapeutically complemented sunitinib therapy, an anti-angiogenic tyrosine kinase inhibitor which limited the local growth of residual disease. Unexpectedly, detailed investigations into the putative mechanism of action of VT revealed no evidence of Tie2 agonism or Tie2 binding; alternative mechanisms have yet to be determined. PMID:25851538

  1. Estrogen receptor agonists for attenuation of neuroinflammation and neurodegeneration

    PubMed Central

    Chakrabarti, Mrinmay; Haque, Azizul; Banik, Naren L.; Nagarkatti, Prakash; Nagarkatti, Mitzi; Ray, Swapan K.

    2014-01-01

    Recent results from laboratory investigations and clinical trials indicate important roles for estrogen receptor (ER) agonists in protecting the central nervous system (CNS) from noxious consequences of neuroinflammation and neurodegeneration. Neurodegenerative processes in several CNS disorders including spinal cord injury (SCI), multiple sclerosis (MS), Parkinson's disease (PD), and Alzheimer's disease (AD) are associated with activation of microglia and astrocytes, which drive the resident neuroinflammatory response. During neurodegenerative processes, activated microglia and astrocytes cause deleterious effects on surrounding neurons. The inhibitory activity of ER agonists on microglia activation might be a beneficial therapeutic option for delaying the onset or progression of neurodegenerative injuries and diseases. Recent studies suggest that ER agonists can provide neuroprotection by modulation of cell survival mechanisms, synaptic reorganization, regenerative responses to axonal injury, and neurogenesis process. The anti-inflammatory and neuroprotective actions of ER agonists are mediated mainly via two ERs known as ERα and ERβ. Although some studies have suggested that ER agonists may be deleterious to some neuronal populations, the potential clinical benefits of ER agonists for augmenting cognitive function may triumph over the associated side effects. Also, understanding the modulatory activities of ER agonists on inflammatory pathways will possibly lead to the development of selective anti-inflammatory molecules with neuroprotective roles in different CNS disorders such as SCI, MS, PD, and AD in humans. Future studies should be concentrated on finding the most plausible molecular pathways for enhancing protective functions of ER agonists in treating neuroinflammatory and neurodegenerative injuries and diseases in the CNS. PMID:25245209

  2. Rational Drug Design Leading to the Identification of a Potent 5-HT2C Agonist Lacking 5-HT2B Activity

    PubMed Central

    2011-01-01

    The 5-HT2C receptor is an attractive drug target in the quest for new therapeutics to treat a variety of human disorders. We have previously undertaken a structural optimization campaign that has led to some potent and moderately selective 5-HT2C receptor agonists. After expanding our structure–function library, we were able to combine our data sets so as to allow the design of compounds of improved selectivity and potency. We disclose herein the structural optimization of our previously reported 5-HT2B/5-HT2C agonists, which has led to the identification of a highly selective 5-HT2C agonist, (+)-trans-[2-(2-cyclopropylmethoxyphenyl)cyclopropyl]methylamine hydrochloride, with an EC50 of 55 nM and no detectable agonism at the 5-HT2B receptor. PMID:22778800

  3. Activation of estrogen receptor signaling by the dioxin-like aryl hydrocarbon receptor agonist, 3,3',4,4',5-Pentachlorobiphenyl (PCB126) in salmon in vitro system

    SciTech Connect

    Mortensen, Anne Skjetne; Arukwe, Augustine

    2008-03-01

    Available toxicological evidence indicates that environmental contaminants with strong affinity to the aryl hydrocarbon receptor (AhR) have anti-estrogenic properties in both mammalian and non-mammalian in vivo and in vitro studies. The primary objective of the present study was to investigate the interactions between the AhR and estrogen receptor (ER) in salmon in vitro system. Two separate experiments were performed and gene expression patterns were analyzed using real-time PCR, while protein analysis was done by immunoblotting. Firstly, salmon primary hepatocytes were exposed to the dioxin-like PCB126 at 1, 10 and 50 pM and ER agonist nonylphenol (NP) at 5 and 10 {mu}M, singly or in combination. Our data showed increased levels of ER-mediated gene expression (vitellogenin: Vtg, zona radiata protein: Zr-protein, ER{alpha}, ER{beta} and vigilin) as well as increased cellular ER{alpha} protein levels after treatment with NP and PCB126, singly or in combination. PCB126 treatment alone produced, as expected, increased transcription of AhR nuclear translocator (Arnt), CYP1A1 and AhR repressor (AhRR) mRNA, and these responses were reduced in the presence of NP concentrations. PCB126 exposure alone did not produce significant effect on AhR2{alpha} mRNA but increased (at 1 and 50 pM) and decreased (at 10 pM) AhR2{beta} mRNA below control level. For AhR2{delta} and AhR2{gamma} isotypes, PCB126 (at 1 pM) produced significant decreases (total inhibition for AhR2{gamma}) of mRNA levels but was indifferent at 10 and 50 pM, compared to control. NP exposure alone produced concentration-dependent significant decrease of AhR2{beta} mRNA. In contrast, while 5 {mu}M NP produced an indifferent effect on AhR2{delta} and AhR2{gamma}, 10 {mu}M NP produced significant decrease (total inhibition for AhR2{gamma}) and the presence of NP produced apparent PCB126 concentration-specific modulation of all AhR isotypes. A second experiment was performed to evaluate the involvement of ER isoforms in PCB126 mediated estrogenicity. Here, cells were treated with the different concentrations of PCB126, alone or in combination with ICI182,780 (ICI) and sampled at 12, 24 and 48 h post-exposure. Our data showed that PCB126 produced a time- and concentration-specific increase of ER{alpha} and Vtg expressions and these responses were decreased in the presence of ICI. In general, these responses show a direct PCB126 induced transcriptional activation of ER{alpha} and estrogenic responses in the absence of ER agonists. Although not conclusive, our findings represent the first study showing the activation of estrogenic responses by a dioxin-like PCB in fish in vitro system and resemble the 'ER-hijacking' hypothesis that was recently proposed. Thus, the direct estrogenic actions of PCB126 observed in the present study add new insight on the mechanisms of ER-AhR cross-talk, prompting a new wave of discussion on whether AhR-mediated anti-estrogenicity is an exception rather than rule of action.

  4. TRPV4 agonists and antagonists.

    PubMed

    Vincent, Fabien; Duncton, Matthew A J

    2011-01-01

    TRPV4 belongs to the TRPV subfamily of Transient Receptor Potential (TRP) ion channels. This year marks the 10 year anniversary of the discovery of this polymodal ion channel which is activated by a variety of stimuli including warm temperatures, hypotonicity and endogenous lipids. Coupled with a widespread tissue distribution, this activation profile has resulted in a large number of disparate physiological functions for TRPV4. These range from temperature monitoring in skin keratinocytes to osmolarity sensing in kidneys, sheer stress detection in blood vessels and osteoclast differentiation control in bone. As knowledge of its physiological roles has expanded, interest in targeting TRPV4 modulation for therapeutic purposes has arisen and is now focused on several areas. First, as with related TRP channels TRPV1, TRPV3, TRPM8 and TRPA1, TRPV4 antagonism is being considered for inflammatory and neuropathic pain treatment. Recent work conducted using KO mice and agonists 4?PDD and GSK1016790A suggests bladder dysfunctions may also be targeted. Additionally, ventilator-induced lung injury has emerged as another potential indication for TRPV4 antagonists. Herein we review the known small molecule modulators of TRPV4 and relate progress made in identifying potent, selective and bioavailable agonists and antagonists to interrogate this ion channel in vivo. PMID:21671873

  5. Induction of ovarian activity and ovulation in an induced ovulator, the maned wolf (Chrysocyon brachyurus), using GnRH agonist and recombinant LH.

    PubMed

    Johnson, Amy E M; Freeman, Elizabeth W; Colgin, Mark; McDonough, Caitlin; Songsasen, Nucharin

    2014-07-01

    Assisted reproductive techniques, such as ovarian manipulation and artificial insemination, are useful for enhancing genetic management of threatened wildlife maintained ex situ. In this study, we used noninvasive fecal hormone monitoring to investigate (1) the influence of pairing with a male on endocrine responses of female maned wolves (Chrysocyon brachyurus) to a GnRH agonist (deslorelin) and (2) the efficiency of recombinant LH (reLH) on ovulation induction in females housed alone. Deslorelin (2.1 mg Ovuplant) was given to females that were either paired with a male (n = 4) or housed alone (n = 7); the implant was removed 7 to 11 days postimplantation. Three of seven singleton females were injected with reLH (0.0375 mg) on the day of implant removal, whereas the remaining females (n = 4) did not receive the additional treatment. Fecal samples were collected 5 to 7 days/wk from all females starting 11 days prior to hormone insertion until at least 70 days post implant removal for a total of 11 hormone treatment cycles. Fecal estrogen and progestagen metabolites were extracted and analyzed by enzyme immunoassay. Evidence of ovulation, demonstrated by a surge of estrogen followed by a significant rise in progestagen, occurred in all paired females. Three of the four singleton females that did not receive reLH treatment exhibited no rise in progestagen after an estrogen surge. All singleton females treated with reLH exhibited a rise in fecal progestagen after injection, indicating ovulation. In conclusion, deslorelin is effective at inducing ovarian activity and ovulation in paired female maned wolves; however, exogenous reLH is needed to induce ovulation in females housed alone. The findings obtained from this study serve as a foundation for future application of artificial insemination to enhance genetic management of this threatened species ex situ. PMID:24742964

  6. The peroxisome-proliferator-activated receptor alpha agonist ciprofibrate severely aggravates hypercholesterolaemia and accelerates the development of atherosclerosis in mice lacking apolipoprotein E.

    PubMed Central

    Fu, Tao; Kashireddy, Papreddy; Borensztajn, Jayme

    2003-01-01

    Mice lacking apolipoprotein E (apoE) are characterized by severe hypercholesterolaemia, caused by an abnormal accumulation of apolipoprotein B-48 (apoB-48)-carrying remnants of chylomicrons and very-low-density lipoproteins (VLDL) in the plasma, and by the spontaneous development of atherosclerotic lesions. Ciprofibrate is a hypolipidaemic compound that acts primarily by enhancing the oxidation of fatty acids in the liver and, consequently, decreasing the production of hepatic VLDL. In the present study, homozygous apoE-deficient mice were fed with a normal chow diet, supplemented with ciprofibrate. We report that, as anticipated, ciprofibrate treatment (a) stimulated hepatic fatty acid oxidation, as indicated by an increase in the mRNA levels of peroxisomal fatty acyl-CoA oxidase (AOX) and peroxisomal bifunctional enzyme, and (b) decreased the hepatic secretion of VLDL into the plasma, as determined by treating the animals with Triton WR-1339. Paradoxically, the apoE-deficient mice developed a 3-4-fold increase in their plasma cholesterol levels. A similar effect was observed in apoE-deficient mice treated with other peroxisome-proliferator-activated receptor alpha agonists (fenofibrate, bezafibrate and WY14,643). By FPLC of the plasma and Western-blot analysis, we determined that the enhanced hypercholesterolaemia was due to an increased accumulation of apoB-48-carrying lipoprotein remnants in the plasma. Consistent with this finding, atherosclerotic lesions in animals treated with ciprofibrate for 90 days were considerably more advanced than in untreated animals. These results indicate that the ciprofibrate-induced accumulation of apoB-48-carrying remnants in apoE-deficient mice is caused by the inhibition of an as yet uncharacterized apoE-independent mechanism of removal of remnant from the circulation by the liver. PMID:12713444

  7. Mechanisms underlying activation of transient BK current in rabbit urethral smooth muscle cells and its modulation by IP3-generating agonists.

    PubMed

    Kyle, Barry D; Bradley, Eamonn; Large, Roddy; Sergeant, Gerard P; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

    2013-09-15

    We used the perforated patch-clamp technique at 37°C to investigate the mechanisms underlying the activation of a transient large-conductance K(+) (tBK) current in rabbit urethral smooth muscle cells. The tBK current required an elevation of intracellular Ca(2+), resulting from ryanodine receptor (RyR) activation via Ca(2+)-induced Ca(2+) release, triggered by Ca(2+) influx through L-type Ca(2+) (CaV) channels. Carbachol inhibited tBK current by reducing Ca(2+) influx and Ca(2+) release and altered the shape of spike complexes recorded under current-clamp conditions. The tBK currents were blocked by iberiotoxin and penitrem A (300 and 100 nM, respectively) and were also inhibited when external Ca(2+) was removed or the CaV channel inhibitors nifedipine (10 μM) and Cd(2+) (100 μM) were applied. The tBK current was inhibited by caffeine (10 mM), ryanodine (30 μM), and tetracaine (100 μM), suggesting that RyR-mediated Ca(2+) release contributed to the activation of the tBK current. When IP3 receptors (IP3Rs) were blocked with 2-aminoethoxydiphenyl borate (2-APB, 100 μM), the amplitude of the tBK current was not reduced. However, when Ca(2+) release via IP3Rs was evoked with phenylephrine (1 μM) or carbachol (1 μM), the tBK current was inhibited. The effect of carbachol was abolished when IP3Rs were blocked with 2-APB or by inhibition of muscarinic receptors with the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (1 μM). Under current-clamp conditions, bursts of action potentials could be evoked with depolarizing current injection. Carbachol reduced the number and amplitude of spikes in each burst, and these effects were reduced in the presence of 2-APB. In the presence of ryanodine, the number and amplitude of spikes were also reduced, and carbachol was without further effect. These data suggest that IP3-generating agonists can modulate the electrical activity of rabbit urethral smooth muscle cells and may contribute to the effects of neurotransmitters on urethral tone. PMID:23804200

  8. Mechanisms underlying activation of transient BK current in rabbit urethral smooth muscle cells and its modulation by IP3-generating agonists

    PubMed Central

    Kyle, Barry D.; Bradley, Eamonn; Large, Roddy; Sergeant, Gerard P.; McHale, Noel G.; Thornbury, Keith D.

    2013-01-01

    We used the perforated patch-clamp technique at 37°C to investigate the mechanisms underlying the activation of a transient large-conductance K+ (tBK) current in rabbit urethral smooth muscle cells. The tBK current required an elevation of intracellular Ca2+, resulting from ryanodine receptor (RyR) activation via Ca2+-induced Ca2+ release, triggered by Ca2+ influx through L-type Ca2+ (CaV) channels. Carbachol inhibited tBK current by reducing Ca2+ influx and Ca2+ release and altered the shape of spike complexes recorded under current-clamp conditions. The tBK currents were blocked by iberiotoxin and penitrem A (300 and 100 nM, respectively) and were also inhibited when external Ca2+ was removed or the CaV channel inhibitors nifedipine (10 μM) and Cd2+ (100 μM) were applied. The tBK current was inhibited by caffeine (10 mM), ryanodine (30 μM), and tetracaine (100 μM), suggesting that RyR-mediated Ca2+ release contributed to the activation of the tBK current. When IP3 receptors (IP3Rs) were blocked with 2-aminoethoxydiphenyl borate (2-APB, 100 μM), the amplitude of the tBK current was not reduced. However, when Ca2+ release via IP3Rs was evoked with phenylephrine (1 μM) or carbachol (1 μM), the tBK current was inhibited. The effect of carbachol was abolished when IP3Rs were blocked with 2-APB or by inhibition of muscarinic receptors with the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (1 μM). Under current-clamp conditions, bursts of action potentials could be evoked with depolarizing current injection. Carbachol reduced the number and amplitude of spikes in each burst, and these effects were reduced in the presence of 2-APB. In the presence of ryanodine, the number and amplitude of spikes were also reduced, and carbachol was without further effect. These data suggest that IP3-generating agonists can modulate the electrical activity of rabbit urethral smooth muscle cells and may contribute to the effects of neurotransmitters on urethral tone. PMID:23804200

  9. The peptidic urotensin-II receptor ligand GSK248451 possesses less intrinsic activity than the low-efficacy partial agonists SB-710411 and urantide in native mammalian tissues and recombinant cell systems

    PubMed Central

    Behm, David J; Stankus, Gerald; Doe, Christopher P A; Willette, Robert N; Sarau, Henry M; Foley, James J; Schmidt, Dulcie B; Nuthulaganti, Parvathi; Fornwald, James A; Ames, Robert S; Lambert, David G; Calo', Girolamo; Camarda, Valeria; Aiyar, Nambi V; Douglas, Stephen A

    2006-01-01

    Several peptidic urotensin-II (UT) receptor antagonists exert ‘paradoxical' agonist activity in recombinant cell- and tissue-based bioassay systems, likely the result of differential urotensin-II receptor (UT receptor) signal transduction/coupling efficiency between assays. The present study has examined this phenomenon in mammalian arteries and recombinant UT-HEK (human embryonic kidney) cells. BacMam-mediated recombinant UT receptor upregulation in HEK cells augmented agonist activity for all four peptidic UT ligands studied. The nominal rank order of relative intrinsic efficacy was U-II>urantide ([Pen5-DTrp7-Orn8]hU-II4–11)>SB-710411 (Cpa-c[DCys-Pal-DTrp-Lys-Val-Cys]-Cpa-amide)≫GSK248451 (Cin-c[DCys-Pal-DTrp-Orn-Val-Cys]-His-amide) (the relative coupling efficiency of recombinant HEK cells was cat>human≫rat UT receptor). The present study further demonstrated that the use of high signal transduction/coupling efficiency isolated blood vessel assays (primate>cat arteries) is required in order to characterize UT receptor antagonism thoroughly. This cannot be attained simply by using the rat isolated aorta, an artery with low signal transduction/coupling efficiency in which low-efficacy agonists appear to function as antagonists. In contrast to the ‘low-efficacy agonists' urantide and SB-710411, GSK248451 functioned as a potent UT receptor antagonist in all native isolated tissues studied (UT receptor selectivity was confirmed in the rat aorta). Further, GSK248451 exhibited an extremely low level of relative intrinsic activity in recombinant HEK cells (4–5-fold less than seen with urantide). Since GSK248451 (1 mg kg−1, i.v.) blocked the systemic pressor actions of exogenous U-II in the anaesthetized cat, it represents a suitable peptidic tool antagonist for delineating the role of U-II in the aetiology of mammalian cardiometabolic diseases. PMID:16547525

  10. Discovery of the First Selective, Nonpeptidic Orexin 2 Receptor Agonists.

    PubMed

    Heifetz, Alexander; Bodkin, Mike J; Biggin, Philip C

    2015-10-22

    In this issue, Nagase and colleagues report the discovery of the first selective nonpeptidic orexin 2 receptor (OX2R) agonists. The discovery of these OX2R selective agonists opens up new avenues for therapies related to the activation of the orexin system, especially with respect to the treatment of sleep disorders such as narcolepsy. PMID:26375584

  11. Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1957-06-01

    Experimental results on the non-conservation of parity and charge conservation in weak interactions are reviewed. The two-component theory of the neutrino is discussed. Lepton reactions are examined under the assumption of the law of conservation of leptons and that the neutrino is described by a two- component theory. From the results of this examination, the universal Fermi interactions are analyzed. Although reactions involving the neutrino can be described, the same is not true of reactions which do not involve the lepton, as the discussion of the decay of K mesons and hyperons shows. The question of the invariance of time reversal is next examined. (J.S.R.)

  12. Development of a Highly Potent D2/D3 Agonist and a Partial Agonist from Structure-Activity Relationship Study of N(6)-(2-(4-(1H-Indol-5-yl)piperazin-1-yl)ethyl)-N(6)-propyl-4,5,6,7-tetrahydrobenzo[d]thiazole-2,6-diamine Analogues: Implication in the Treatment of Parkinson's Disease.

    PubMed

    Das, Banibrata; Vedachalam, Seenuvasan; Luo, Dan; Antonio, Tamara; Reith, Maarten E A; Dutta, Aloke K

    2015-12-10

    Our structure-activity relationship studies with N(6)-(2-(4-(1H-indol-5-yl)piperazin-1-yl)ethyl)-N(6)-propyl-4,5,6,7-tetrahydrobenzo[d]thiazole-2,6-diamine derivatives led to development of a lead compound (-)-21a which exhibited very high affinity (Ki, D2 = 16.4 nM, D3 = 1.15 nM) and full agonist activity (EC50 (GTPγS); D2 = 3.23 and D3 = 1.41 nM) at both D2 and D3 receptors. A partial agonist molecule (-)-34 (EC50 (GTPγS); D2 = 21.6 (Emax = 27%) and D3 = 10.9 nM) was also identified. In a Parkinson's disease (PD) animal model, (-)-21a was highly efficacious in reversing hypolocomotion in reserpinized rats with a long duration of action, indicating its potential as an anti-PD drug. Compound (-)-34 was also able to elevate locomotor activity in the above PD animal model significantly, implying its potential application in PD therapy. Furthermore, (-)-21a was shown to be neuroprotective in protecting neuronal PC12 from toxicity of 6-OHDA. This report, therefore, underpins the notion that a multifunctional drug like (-)-21a might have the potential not only to ameliorate motor dysfunction in PD patients but also to modify disease progression by protecting DA neurons from progressive degeneration. PMID:26555041

  13. Phosphodiesterase inhibitor KMUP-3 displays cardioprotection via protein kinase G and increases cardiac output via G-protein-coupled receptor agonist activity and Ca(2+) sensitization.

    PubMed

    Liu, Chung-Pin; Yeh, Jwu-Lai; Liou, Shu-Fen; Wu, Bin-Nan; Chen, Ing-Jun

    2016-02-01

    KMUP-3 (7-{2-[4-(4-nitrobenzene) piperazinyl]ethyl}-1, 3-dimethylxanthine) displays cardioprotection and increases cardiac output, and is suggested to increase cardiac performance and improve myocardial infarction. To determine whether KMUP-3 improves outcomes in hypoperfused myocardium by inducing Ca(2+) sensitization to oppose protein kinase (PK)G-mediated Ca(2+) blockade, we measured left ventricular systolic blood pressure, maximal rates of pressure development, mean arterial pressure and heart rate in rats, and measured contractility and expression of PKs/RhoA/Rho kinase (ROCK)II in beating guinea pig left atria. Hemodynamic changes induced by KMUP-3 (0.5-3.0 mg/kg, intravenously) were inhibited by Y27632 [(R)-(+)-trans-4-1-aminoethyl)-N-(4-Pyridyl) cyclohexane carboxamide] and ketanserin (1 mg/kg, intravenously). In electrically stimulated left guinea pig atria, positive inotropy induced by KMUP-3 (0.1-100μM) was inhibited by the endothelial NO synthase (eNOS) inhibitors N-nitro-l-arginine methyl ester (L-NAME) and 7-nitroindazole, cyclic AMP antagonist SQ22536 [9-(terahydro-2-furanyl)-9H-purin-6-amine], soluble guanylyl cyclase (sGC) antagonist ODQ (1H-[1,2,4] oxadiazolo[4,3-a] quinoxalin-1-one), RhoA inhibitor C3 exoenzyme, β-blocker propranolol, 5-hydroxytryptamine 2A antagonist ketanserin, ROCK inhibitor Y27632 and KMUP-1 (7-{2-[4-(2-chlorobenzene) piperazinyl]ethyl}-1, 3-dimethylxanthine) at 10μM. Western blotting assays indicated that KMUP-3 (0.1-10μM) increased PKA, RhoA/ROCKII, and PKC translocation and CIP-17 (an endogenous 17-kDa inhibitory protein) activation. In spontaneous right atria, KMUP-3 induced negative chronotropy that was blunted by 7-nitroindazole and atropine. In neonatal myocytes, L-NAME inhibited KMUP-3-induced eNOS phosphorylation and RhoA/ROCK activation. In H9c2 cells, Y-27632 (50μM) and PKG antagonist KT5823 [2,3,9,10,11,12-hexahydro-10R- methoxy-2,9-dimethyl-1-oxo-9S,12R-epoxy-1H-diindolo(1,2,3-fg:3',2',1'-kl) pyrrolo(3,4-i)(1,6)benzodiazocine-10-carboxylic acid, methyl e