101
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Zhang Y, Sheng H, Qi J, Ma B, Sun J, Li S, Ni X. Glucocorticoid acts on a putative G protein-coupled receptor to rapidly regulate the activity of NMDA receptors in hippocampal neurons. Am J Physiol Endocrinol Metab 2012; 302:E747-58. [PMID: 22146309 DOI: 10.1152/ajpendo.00302.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucocorticoids (GCs) have been demonstrated to act through both genomic and nongenomic mechanisms. The present study demonstrated that corticosterone rapidly suppressed the activity of N-methyl-D-aspartate (NMDA) receptors in cultured hippocampal neurons. The effect was maintained with corticosterone conjugated to bovine serum albumin and blocked by inhibition of G protein activity with intracellular GDP-β-S application. Corticosterone increased GTP-bound G(s) protein and cyclic AMP (cAMP) production, activated phospholipase Cβ(3) (PLC-β(3)), and induced inositol-1,4,5-triphosphate (IP(3)) production. Blocking PLC and the downstream cascades with PLC inhibitor, IP(3) receptor antagonist, Ca(2+) chelator, and protein kinase C (PKC) inhibitors prevented the actions of corticosterone. Blocking adenylate cyclase (AC) and protein kinase A (PKA) caused a decrease in NMDA-evoked currents. Application of corticosterone partly reversed the inhibition of NMDA currents caused by blockage of AC and PKA. Intracerebroventricular administration of corticosterone significantly suppressed long-term potentiation (LTP) in the CA1 region of the hippocampus within 30 min in vivo, implicating the possibly physiological significance of rapid effects of GC on NMDA receptors. Taken together, our results indicate that GCs act on a putative G protein-coupled receptor to activate multiple signaling pathways in hippocampal neurons, and the rapid suppression of NMDA activity by GCs is dependent on PLC and downstream signaling.
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MESH Headings
- Animals
- Blotting, Western
- CA1 Region, Hippocampal/cytology
- CA1 Region, Hippocampal/drug effects
- CA1 Region, Hippocampal/metabolism
- Cells, Cultured
- Cyclic AMP/metabolism
- Excitatory Postsynaptic Potentials
- Female
- Glucocorticoids/pharmacology
- Hippocampus/cytology
- Hippocampus/drug effects
- Hippocampus/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Long-Term Potentiation/drug effects
- Male
- Neurons/drug effects
- Neurons/metabolism
- Patch-Clamp Techniques
- Pregnancy
- Radioimmunoassay
- Rats
- Rats, Sprague-Dawley
- Receptors, G-Protein-Coupled/drug effects
- Receptors, Glucocorticoid/drug effects
- Receptors, N-Methyl-D-Aspartate/metabolism
- Signal Transduction/drug effects
- Synapses/drug effects
- Synapses/physiology
- Type C Phospholipases/metabolism
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Affiliation(s)
- Yanmin Zhang
- Department of Physiology, Second Military Medical University, Shanghai, China
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102
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Digby JE, Martinez F, Jefferson A, Ruparelia N, Chai J, Wamil M, Greaves DR, Choudhury RP. Anti-inflammatory effects of nicotinic acid in human monocytes are mediated by GPR109A dependent mechanisms. Arterioscler Thromb Vasc Biol 2012; 32:669-76. [PMID: 22267479 DOI: 10.1161/atvbaha.111.241836] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Nicotinic acid (NA) treatment has been associated with benefits in atherosclerosis that are usually attributed to effects on plasma lipoproteins. The NA receptor GPR109A is expressed in monocytes and macrophages, suggesting a possible additional role for NA in modulating function of these immune cells. We hypothesize that NA has the potential to act directly on monocytes to alter mediators of inflammation that may contribute to its antiatherogenic effects in vivo. METHODS AND RESULTS In human monocytes activated by Toll-like receptor (TLR)-4 agonist lipopolysaccharide, NA reduced secretion of proinflammatory mediators: TNF-α (by 49.2±4.5%); interleukin-6 (by 56.2±2.8%), and monocyte chemoattractant protein-1 (by 43.2±3.1%) (P<0.01). In TLR2 agonist, heat-killed Listeria monocytogenes-activated human monocytes, NA reduced secretion of TNF-α (by 48.6±7.1%), interleukin-6 (by 60.9±1.6%), and monocyte chemoattractant protein-1 (by 59.3±5.3%) (P<0.01; n=7). Knockdown of GPR109A by siRNA resulted in a loss of this anti-inflammatory effect in THP-1 monocytes. However, inhibition of prostaglandin D2 receptor by MK0524 or COX2 by NS398 did not alter the anti-inflammatory effects of NA observed in activated human monocytes. Preincubation of THP-1 monocytes with NA 0.1 mmol/L reduced phosphorylated IKKβ by 42±2% (P<0.001) IKB-α by 54±14% (P<0.01). Accumulation of nuclear p65 NF-κB in response to lipopolysaccharide treatment was also profoundly inhibited, by 89±1.3% (n=4; P<0.01). NA potently inhibited monocyte adhesion to activated HUVEC, and VCAM, mediated by the integrin, very late antigen 4. Monocyte chemotaxis was also significantly reduced (by 45.7±1.2%; P<0.001). CONCLUSION NA displays a range of effects that are lipoprotein-independent and potentially antiatherogenic. These effects are mediated by GPR109A and are independent of prostaglandin pathways. They suggest a rationale for treatment with NA that is not dependent on levels of plasma cholesterol and possible applications beyond the treatment of dyslipidemia.
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MESH Headings
- Anti-Inflammatory Agents/pharmacology
- Cell Adhesion/drug effects
- Cells, Cultured
- Chemokine CCL2/metabolism
- Chemotaxis, Leukocyte/drug effects
- Cyclooxygenase 2 Inhibitors/pharmacology
- Human Umbilical Vein Endothelial Cells/drug effects
- Human Umbilical Vein Endothelial Cells/immunology
- Human Umbilical Vein Endothelial Cells/metabolism
- Humans
- I-kappa B Kinase/metabolism
- Inflammation/genetics
- Inflammation/immunology
- Inflammation/metabolism
- Inflammation Mediators/metabolism
- Integrin alpha4beta1/metabolism
- Interleukin-6/metabolism
- Lipopolysaccharides/pharmacology
- Monocytes/drug effects
- Monocytes/immunology
- Monocytes/metabolism
- Niacin/pharmacology
- Phosphorylation
- Pyrazines/pharmacology
- RNA Interference
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Immunologic/antagonists & inhibitors
- Receptors, Immunologic/metabolism
- Receptors, Nicotinic/drug effects
- Receptors, Nicotinic/genetics
- Receptors, Nicotinic/metabolism
- Receptors, Prostaglandin/antagonists & inhibitors
- Receptors, Prostaglandin/metabolism
- Toll-Like Receptor 2/agonists
- Toll-Like Receptor 2/metabolism
- Toll-Like Receptor 4/agonists
- Toll-Like Receptor 4/metabolism
- Transcription Factor RelA/metabolism
- Transfection
- Tumor Necrosis Factor-alpha/metabolism
- Vascular Cell Adhesion Molecule-1/metabolism
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Affiliation(s)
- Janet E Digby
- Department of Cardiovascular Medicine, John Radcliffe Hospital, and Sir William Dunn School of Pathology, University of Oxford, Oxford, OX3 9DU, UK
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103
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Abstract
The receptor activity-modifying protein (RAMP) family of membrane proteins regulates G protein-coupled receptor (GPCR) function in several ways. RAMPs can alter their pharmacology and signalling as well as the trafficking of these receptors to and from the cell surface. Accordingly, RAMPs may be exploited as drug targets, offering new opportunities for regulating the function of therapeutically relevant RAMP-interacting GPCRs. For example, several small molecule antagonists of RAMP1/ calcitonin receptor-like receptor complexes, which block the actions of the neuropeptide calcitonin gene-related peptide are in development for the treatment of migraine headache.
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Affiliation(s)
- Patrick M Sexton
- Department of Pharmacology, Monash University, Victoria, Australia
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104
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Chorin E, Vinograd O, Fleidervish I, Gilad D, Herrmann S, Sekler I, Aizenman E, Hershfinkel M. Upregulation of KCC2 activity by zinc-mediated neurotransmission via the mZnR/GPR39 receptor. J Neurosci 2011; 31:12916-26. [PMID: 21900570 PMCID: PMC3227684 DOI: 10.1523/jneurosci.2205-11.2011] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/12/2011] [Accepted: 07/14/2011] [Indexed: 12/15/2022] Open
Abstract
Vesicular Zn(2+) regulates postsynaptic neuronal excitability upon its corelease with glutamate. We previously demonstrated that synaptic Zn(2+) acts via a distinct metabotropic zinc-sensing receptor (mZnR) in neurons to trigger Ca(2+) responses in the hippocampus. Here, we show that physiological activation of mZnR signaling induces enhanced K(+)/Cl(-) cotransporter 2 (KCC2) activity and surface expression. As KCC2 is the major Cl(-) outward transporter in neurons, Zn(2+) also triggers a pronounced hyperpolarizing shift in the GABA(A) reversal potential. Mossy fiber stimulation-dependent upregulation of KCC2 activity is eliminated in slices from Zn(2+) transporter 3-deficient animals, which lack synaptic Zn(2+). Importantly, activity-dependent ZnR signaling and subsequent enhancement of KCC2 activity are also absent in slices from mice lacking the G-protein-coupled receptor GPR39, identifying this protein as the functional neuronal mZnR. Our work elucidates a fundamentally important role for synaptically released Zn(2+) acting as a neurotransmitter signal via activation of a mZnR to increase Cl(-) transport, thereby enhancing inhibitory tone in postsynaptic cells.
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MESH Headings
- Animals
- Blotting, Western
- CA3 Region, Hippocampal/cytology
- CA3 Region, Hippocampal/physiology
- Electrophysiological Phenomena
- Excitatory Postsynaptic Potentials/physiology
- Female
- Genotype
- In Vitro Techniques
- Male
- Mice
- Mice, Knockout
- Microscopy, Fluorescence
- Mossy Fibers, Hippocampal/physiology
- Patch-Clamp Techniques
- Receptors, Cell Surface/metabolism
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/genetics
- Receptors, GABA-A/drug effects
- Reverse Transcriptase Polymerase Chain Reaction
- Symporters/biosynthesis
- Symporters/physiology
- Synapses/metabolism
- Synaptic Transmission/drug effects
- Up-Regulation/drug effects
- Zinc/metabolism
- Zinc/pharmacology
- K Cl- Cotransporters
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Affiliation(s)
| | | | - Ilya Fleidervish
- Physiology, Faculty of Health Sciences and The Zlotowski Center of Neuroscience, Ben-Gurion University, Beer-Sheva, 84015, Israel, and
| | | | - Sharon Herrmann
- Physiology, Faculty of Health Sciences and The Zlotowski Center of Neuroscience, Ben-Gurion University, Beer-Sheva, 84015, Israel, and
| | - Israel Sekler
- Physiology, Faculty of Health Sciences and The Zlotowski Center of Neuroscience, Ben-Gurion University, Beer-Sheva, 84015, Israel, and
| | - Elias Aizenman
- Departments of Morphology and
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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105
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Natividad GM, Broadley KJ, Kariuki B, Kidd EJ, Ford WR, Simons C. Actions of Artemisia vulgaris extracts and isolated sesquiterpene lactones against receptors mediating contraction of guinea pig ileum and trachea. J Ethnopharmacol 2011; 137:808-16. [PMID: 21762766 DOI: 10.1016/j.jep.2011.06.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/13/2011] [Accepted: 06/28/2011] [Indexed: 05/23/2023]
Abstract
AIM OF THE STUDY The present study evaluates the Philippine medicinal plant Artemisia vulgaris for antagonistic activity at selected biogenic amine receptors on smooth muscle of the airways and gastrointestinal tract in order to explain its traditional use in asthma and hyperactive gut. MATERIALS AND METHODS The antagonistic activity of chloroform crude extract (AV-CHCl(3)) and methanol crude extract (AV-MeOH) of Artemisia vulgaris was studied against concentration-response curves for contractions of the guinea pig ileum and trachea to 5-hydroxytrptamine (5-HT(2) receptors), methacholine (M(3) muscarinic receptors), histamine (H(1) receptors) and β-phenylethylamine (trace amine-associated receptors, TAAR1). RESULTS AND DISCUSSION The Artemisia vulgaris chloroform (AV-CHCl(3)) and methanol (AV-MeOH) extract showed histamine H1 antagonism in the ileum and trachea. Further analysis of AV-CHCl(3) isolated two major components, yomogin and 1,2,3,4-diepoxy-11(13)-eudesmen-12,8-olide. Yomogin, a sesquiterpene lactone, exhibited a novel histamine H1 receptor antagonism in the ileum. CONCLUSION The presence of a specific, competitive histamine receptor antagonist and smooth muscle relaxant activity in Artemisia vulgaris extracts on the smooth muscle in ileum and trachea explains its traditional use in the treatment of asthma and hyperactive gut.
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MESH Headings
- Animals
- Artemisia/chemistry
- Chloroform/chemistry
- Dose-Response Relationship, Drug
- Guinea Pigs
- Histamine H1 Antagonists/pharmacology
- Ileum/drug effects
- Ileum/metabolism
- In Vitro Techniques
- Lactones/pharmacology
- Male
- Methanol/chemistry
- Muscle Contraction/drug effects
- Muscle Relaxation/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Neurotransmitter Agents/chemistry
- Neurotransmitter Agents/isolation & purification
- Neurotransmitter Agents/pharmacology
- Plant Extracts/chemistry
- Plant Extracts/isolation & purification
- Plant Extracts/pharmacology
- Plants, Medicinal
- Receptor, Muscarinic M3/drug effects
- Receptor, Muscarinic M3/metabolism
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Histamine H1/drug effects
- Receptors, Histamine H1/metabolism
- Receptors, Serotonin, 5-HT2/drug effects
- Receptors, Serotonin, 5-HT2/metabolism
- Sesquiterpenes, Eudesmane/chemistry
- Sesquiterpenes, Eudesmane/isolation & purification
- Sesquiterpenes, Eudesmane/pharmacology
- Solvents/chemistry
- Trachea/drug effects
- Trachea/metabolism
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Affiliation(s)
- Gaudencio M Natividad
- Welsh School of Pharmacy, Cardiff University, King Edward VII Avenue, Cardiff CF10 3NB, UK
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106
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Festring D, Brockhoff A, Meyerhof W, Hofmann T. Stereoselective synthesis of amides sharing the guanosine 5'-monophosphate scaffold and Umami enhancement studies using human sensory and hT1R1/rT1R3 receptor assays. J Agric Food Chem 2011; 59:8875-8885. [PMID: 21770456 DOI: 10.1021/jf202202h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent studies led to the identification of umami-enhancing (S)-N(2)-(1-carboxyethyl)- and (S)-N(2)-(1-alkylamino)carbonylalkyl)guanosine 5'-monophosphates that, together with their sensorially inactive (R)-stereoisomers, were found to be formed upon Maillard-type glycation of guanosine 5'-monophosphate (5'-GMP) with 1,3-dihydroxyacetone or glyceraldehyde, respectively. As the efficiency of this Maillard-type procedure to generate the amidated derivatives is limited by the low solubility and reactivity of long-chain alkyl amines as well as by the tedious separation of the diastereomers formed, a versatile synthesis for the (R)- and (S)-configured amides of N(2)-carboxyalkylated guanosine 5'-monophosphate was developed. Sensory evaluation of a series of N(2)-(1-alkylamino)carbonylalkyl)guanosine 5'-monophosphates revealed β-values for umami enhancement between 0.1 and 7.7 and identified a strong influence of the stereochemistry as well as the chain length of the N(2)-substituent on the umami-enhancing activity. The observed sensory impact of the (S)-configured isomers was confirmed by recording the enhancing effect of these nucleotides on the l-glutamate-induced response of the functionally expressed T1R1/T1R3 umami receptor in a cell-based assay, thus underscoring the stereospecifity of the umami taste receptor binding site.
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Affiliation(s)
- Daniel Festring
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München, Freising-Weihenstephan, Germany
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107
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Pertz HH, Lehmann J, Roth-Ehrang R, Elz S. Effects of ginger constituents on the gastrointestinal tract: role of cholinergic M3 and serotonergic 5-HT3 and 5-HT4 receptors. Planta Med 2011; 77:973-8. [PMID: 21305447 DOI: 10.1055/s-0030-1270747] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The herbal drug ginger (Zingiber officinale Roscoe) may be effective for treating nausea, vomiting, and gastric hypomotility. In these conditions, cholinergic M (3) receptors and serotonergic 5-HT (3) and 5-HT (4) receptors are involved. The major chemical constituents of ginger are [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-shogaol. We studied the interaction of [6]-gingerol, [8]-gingerol, [10]-gingerol (racemates), and [6]-shogaol with guinea pig M (3) receptors, guinea pig 5-HT (3) receptors, and rat 5-HT (4) receptors. In whole segments of guinea pig ileum (bioassay for contractile M (3) receptors), [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-shogaol slightly but significantly depressed the maximal carbachol response at an antagonist concentration of 10 µM. In the guinea pig myenteric plexus preparation (bioassay for contractile 5-HT (3) receptors), 5-HT maximal responses were depressed by [10]-gingerol from 93 ± 3 % to 65 ± 6 % at an antagonist concentration of 3 µM and to 48 ± 3 % at an antagonist concentration of 5 µM following desensitization of 5-HT (4) receptors and blockade of 5-HT (1) and 5-HT (2) receptors. [6]-Shogaol (3 µM) induced depression to 61 ± 3 %. In rat esophageal tunica muscularis mucosae (bioassay for relaxant 5-HT (4) receptors), [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-shogaol (2-6.3 µM) showed no agonist effects. The maximal 5-HT response remained unaffected in the presence of the compounds. It is concluded that the efficiency of ginger in reducing nausea and vomiting may be based on a weak inhibitory effect of gingerols and shogaols at M (3) and 5-HT (3) receptors. 5-HT (4) receptors, which play a role in gastroduodenal motility, appear not to be involved in the action of these compounds.
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MESH Headings
- Animals
- Antiemetics/pharmacology
- Catechols/pharmacology
- Dose-Response Relationship, Drug
- Drug Evaluation, Preclinical
- Esophagus/drug effects
- Fatty Alcohols/pharmacology
- Gastrointestinal Tract/drug effects
- Gastrointestinal Tract/physiology
- Zingiber officinale/chemistry
- Guinea Pigs
- Ileum/drug effects
- Ileum/physiology
- In Vitro Techniques
- Male
- Muscle Contraction/drug effects
- Muscle Relaxation/drug effects
- Myenteric Plexus/drug effects
- Nausea/drug therapy
- Phytotherapy
- Plants, Medicinal
- Rats
- Rats, Wistar
- Receptor, Muscarinic M3/antagonists & inhibitors
- Receptor, Muscarinic M3/physiology
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/physiology
- Receptors, Serotonin, 5-HT3/physiology
- Receptors, Serotonin, 5-HT4/drug effects
- Receptors, Serotonin, 5-HT4/physiology
- Serotonin Antagonists/pharmacology
- Vomiting/drug therapy
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Affiliation(s)
- Heinz H Pertz
- Institut für Pharmazie, Freie Universität Berlin, Berlin (Dahlem), Germany.
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108
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Maudsley S. New frontiers in G protein-coupled receptor regulation of neurological disorders. CNS Neurol Disord Drug Targets 2010; 9:525. [PMID: 20632974 DOI: 10.2174/187152710793361540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 02/25/2010] [Indexed: 05/29/2023]
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109
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Abstract
G protein-coupled receptors are the largest group of membrane proteins and are the targets for approximately 30% of drugs currently used therapeutically. These 7-transmembrane-spanning proteins continue to provide new opportunities to develop therapeutics based on emerging knowledge of their structure, signalling properties and interactions with other proteins. This themed issue of the British Journal of Pharmacology contains a series of papers that cover these issues and identify approaches that may determine future directions. Many of these papers contain material that was presented at the 5th International Molecular Pharmacology of G Protein-Coupled Receptors meeting held in Sydney Australia in late 2008.
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110
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Hipser C, Bushlin I, Gupta A, Gomes I, Devi LA. Role of antibodies in developing drugs that target G-protein-coupled receptor dimers. Mt Sinai J Med 2010; 77:374-80. [PMID: 20687183 PMCID: PMC2917817 DOI: 10.1002/msj.20199] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
G-protein-coupled receptors are important molecular targets in drug discovery. These receptors play a pivotal role in physiological signaling pathways and are targeted by nearly 50% of currently available drugs. Mounting evidence suggests that G-protein-coupled receptors form dimers, and various studies have shown that dimerization is necessary for receptor maturation, signaling, and trafficking. However, the physiological implications of dimerization in vivo have not been well explored because detection of GPCR dimers in endogenous systems has been a challenging task. One exciting new approach to this challenge is the generation of antibodies against specific G-protein-coupled receptor dimers. Such antibodies could be used as tools for characterization of heteromer-specific function; as reagents for their purification, tissue localization, and regulation in vivo; and as probes for mapping their functional domains. In addition, such antibodies could serve as alternative ligands for G-protein-coupled receptor heteromers. Thus, heteromer-specific antibodies represent novel tools for the exploration and manipulation of G-protein-coupled receptor-dimer pharmacology.
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Affiliation(s)
- Chris Hipser
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY, USA
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111
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Wang SS, Zeng YL, Zhang WW, Dong SL. A snake venom peptide with the contrary effects on rat stomach fundus and guinea pig ileum. Pharmazie 2010; 65:384-386. [PMID: 20503934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A bradykinin potentiating peptide (BPP), Thr-Pro-Pro-Ala-Gly-Pro-Asp-Val-Gly-Pro-Arg-OH, was isolated from the venoms of Crotalus viridis viridis (here named Cvv peptide). Compared with other BPP, Cvv peptide has special Thr at N-terminal and Arg at C-terminal. In order to clarify whether these two special amino acids lead to special bioactivities relative to other BPPs, we made bioassays on isolated guinea pig ileum (GPI) and rat stomach fundus. Cvv peptide can observably inhibit bradykinin's contractivity on GPI, but potentiate the bradykinin-induced contractivity on rat stomach fundus. The discrepant bioactivity of Cvv peptide may occur via binding different receptors, B2 receptor on GPI and anaphylatoxin C3a receptor on rat stomach fundus, respectively.
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Affiliation(s)
- Sha-Sha Wang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, China
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112
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Curtis AE, Cooke JH, Baxter JE, Parkinson JRC, Bataveljic A, Ghatei MA, Bloom SR, Murphy KG. A kisspeptin-10 analog with greater in vivo bioactivity than kisspeptin-10. Am J Physiol Endocrinol Metab 2010; 298:E296-303. [PMID: 19934405 PMCID: PMC2822479 DOI: 10.1152/ajpendo.00426.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The kisspeptins are neuropeptides that stimulate the hypothalamo-pituitary-gonadal (HPG) axis. The smallest endogenous kisspeptin, kisspeptin-10 (KP-10), binds to the receptor KISS1R with a similar affinity to the full-length peptide, kisspeptin-54 (KP-54), but is less effective in vivo, possibly because of increased enzymatic breakdown or clearance. The kisspeptin system may have therapeutic potential in the treatment of reproductive disorders and endocrine cancers. We have rationally modified the structure of KP-10 and tested the binding affinity of these analogs for the KISS1R. Those analogs that bound with relatively high affinity to KISS1R were tested for ability to stimulate ERK1/2 phosphorylation in vitro and for their ability to stimulate the HPG axis in vivo. One analog, [dY](1)KP-10, bound to KISS1R with lower affinity to KP-10 and exhibited similar bioactivity in vitro. However, in vivo peripheral administration of [dY](1)KP-10 increased plasma LH and testosterone more potently than KP-10 itself at 20 min postinjection in mice. In addition, 60 min postinjection, 0.15 nmol [dY](1)KP-10 significantly increased total testosterone levels in mice whereas the same dose of KP-10 had no significant effect. Should manipulation of the kisspeptin/KISS1R signaling system prove therapeutically useful, long-lasting analogs such as [dY](1)KP-10 may have greater therapeutic potential than endogenous forms of kisspeptin.
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Affiliation(s)
- Annette E Curtis
- Dept. of Investigative Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Rd., London W12 0NN, UK
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113
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Abstract
Drug discovery is an iterative process with high risks and low chance of success. New genomics technologies allow veterinary medicine and agrochemical companies to validate and functionally screen new receptor-based targets, including neuropeptide G-protein coupled receptors, which were previously not amenable to high throughput screening. However this is just the first step in a long process to translate a mechanistic assay hit into a drug on the market. In addition to effectively eradicating pests on crops and parasites on their host, the molecules must also be safe, cheap to synthesise, formulatable and patentable. This is a costly process in which early attrition of unsuitable molecules is key to any successful program. Although first principle discovery is risky the ultimate benefits are considerable and future genomics resources will help to generate higher quality hits to strengthen the discovery pipeline.
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Affiliation(s)
- Debra Woods
- Pfizer Animal Health, Pfizer Inc, 7000 Portage Road, Kalamazoo, MI, 49009, USA.
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114
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Ide N, Sato E, Ohta K, Masuda T, Kitabatake N. Interactions of the sweet-tasting proteins thaumatin and lysozyme with the human sweet-taste receptor. J Agric Food Chem 2009; 57:5884-5890. [PMID: 19489607 DOI: 10.1021/jf803956f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This study investigated the sweetness of the sweet-tasting protein thaumatin and lysozyme by both an in vitro cell-based assay and an in vivo sensory analysis to elucidate the differences between in vitro and in vivo response profiles. Hek293 cells were constructed that stably expressed the human T1R2+T1R3 sweet-taste receptor, and their responses to thaumatin and lysozyme were analyzed by monitoring the levels of intracellular cAMP. The results indicated that thaumatin and lysozyme as well as aspartame induced a decrease in the intracellular cAMP accumulation of the T1R2+T1R3-transfected cells and that EC(50) values of thaumatin and lysozyme determined by cell-based assay are well-consistent with the results of the sweetness threshold value determined by sensory analysis in the presence of 140 mM NaCl. The results of both in vitro and in vivo experiments confirmed that the sweetness inhibitor lactisole significantly suppressed the sweetness of thaumatin and lysozyme.
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Affiliation(s)
- Nobuyuki Ide
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
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115
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Chang M, Li W, Peng YL, Gao YH, Yao J, Han RW, Wang R. Involvement of NMDA receptor in nociceptive effects elicited by intrathecal [Tyr6] gamma2-MSH(6-12), and the interaction with nociceptin/orphanin FQ in pain modulation in mice. Brain Res 2009; 1271:36-48. [PMID: 19332041 DOI: 10.1016/j.brainres.2009.03.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 03/17/2009] [Accepted: 03/18/2009] [Indexed: 01/21/2023]
Abstract
The mas-related genes (Mrgs, also known as sensory neuron-specific receptors, SNSRs) are specifically expressed in small diameter sensory neurons in the trigeminal and dorsal root ganglia, suggesting an important role of the receptors in pain transmission. The present study aimed to investigate the underlying mechanism of the nociceptive effects after activation of MrgC, and the interaction between MrgC and N/OFQ-NOP receptor system in modulation of nociception in mice. Intrathecal (i.t.) administration of [Tyr(6)] gamma2-MSH(6-12), the most potent agonist for MrgC receptor, produced a significant hyperalgesic response as assayed by tail withdrawal test and a series of characteristic nociceptive responses, including biting, licking and scratching, in a dose-dependent manner (0.01-10 pmol and 0.01-10 nmol, respectively) in mice. These pronociceptive effects induced by [Tyr(6)] gamma2-MSH(6-12) were inhibited dose-dependently by co-injection of competitive NMDA receptor antagonist D-APV, non-competitive NMDA receptor antagonist MK-801, and nitric oxide (NO) synthase inhibitor L-NAME. However, the tachykinin NK(1) receptor antagonist L-703,606, and tachykinin NK(2) receptor antagonist MEN-10,376, had no influence on pronociceptive effects elicited by [Tyr(6)] gamma2-MSH(6-12). In other groups, [Tyr(6)] gamma2-MSH(6-12)-induced nociceptive responses were bidirectionally regulated by the co-injection of N/OFQ. N/OFQ inhibited nociceptive responses at high doses (0.01-1 nmol), but potentiated the behaviors at low doses (1 fmol-3 pmol). Furthermore, both hyperalgesia and nociceptive responses were enhanced after the co-administration with NOP receptor antagonist [Nphe(1)]N/OFQ(1-13)-NH(2). These results suggest that intrathecal [Tyr(6)] gamma2-MSH(6-12)-induced pronociceptive effects may be mediated through NMDA receptor-NO system in the spinal cord, and demonstrate the interaction between MrgC and N/OFQ-NOP receptor system in pain transmission.
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Affiliation(s)
- Min Chang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China
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116
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117
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Sakurai T, Misaka T, Nagai T, Ishimaru Y, Matsuo S, Asakura T, Abe K. pH-Dependent inhibition of the human bitter taste receptor hTAS2R16 by a variety of acidic substances. J Agric Food Chem 2009; 57:2508-2514. [PMID: 19231899 DOI: 10.1021/jf8040148] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Some acidic peptides are known to reduce bitterness, but the detailed mechanism underlying this effect remains to be elucidated. In this study, we analyzed the effects of acidic dipeptides on the inhibition of the human bitter taste receptor hTAS2R16. Calcium imaging analysis of HEK293T cells expressing hTAS2R16 revealed that their response to the bitter tastant salicin was reduced in the presence of acidic dipeptides. A similar inhibitory effect was observed in a variety of other acids. The inhibition depended on the pH values resulting from the addition of acids but not on their concentrations. Our results suggest that the inhibition of the bitter taste receptors can be attributed to the bitterness-masking effect of the acidic dipeptides and that acidic pH may be one of the critical factors responsible for this sensory event.
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Affiliation(s)
- Takanobu Sakurai
- General Research Institute of Food Science and Technology, Nissin Foods Holdings Co, Ltd, Kusatsu-shi, Shiga, Japan
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118
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Nestler HP. Organizing bioactive compound discovery in target families. Methods Mol Biol 2009; 575:1-19. [PMID: 19727609 DOI: 10.1007/978-1-60761-274-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The sequencing of genomes gave access to the complete set of building blocks for organisms of various species. A plethora of "-omics"-technologies has been developed to investigate the dynamic interactions of the building blocks in order to understand the functioning of living organisms. This has given rise to the clustering of proteins into target families based on the phylogenetic and structural similarities. In this chapter we will discuss how the concept of target families enables to investigate and modulate biochemical function in the quest to chart Chemical and Biological Spaces.
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Affiliation(s)
- H Peter Nestler
- Sanofi-Aventis Combinatorial Technologies Center, Tucson, AZ, USA
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119
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Abstract
Acidosis is a noxious condition associated with inflammation, ischaemia or defective acid containment. As a consequence, acid sensing has evolved as an important property of afferent neurons with unmyelinated and thinly myelinated nerve fibres. Protons evoke multiple currents in primary afferent neurons, which are carried by several acid-sensitive ion channels. Among these, acid-sensing ion channels (ASICs) and transient receptor potential (TRP) vanilloid-1 (TRPV1) ion channels have been most thoroughly studied. ASICs survey moderate decreases in extracellular pH, whereas TRPV1 is activated only by severe acidosis resulting in pH values below 6. Two-pore-domain K(+) (K(2P)) channels are differentially regulated by small deviations of extra- or intracellular pH from physiological levels. Other acid-sensitive channels include TRPV4, TRPC4, TRPC5, TRPP2 (PKD2L1), ionotropic purinoceptors (P2X), inward rectifier K(+) channels, voltage-activated K(+) channels, L-type Ca(2+) channels, hyperpolarization-activated cyclic nucleotide gated channels, gap junction channels, and Cl(-) channels. In addition, acid-sensitive G protein coupled receptors have also been identified. Most of these molecular acid sensors are expressed by primary sensory neurons, although to different degrees and in various combinations. Emerging evidence indicates that many of the acid-sensitive ion channels and receptors play a role in acid sensing, acid-induced pain and acid-evoked feedback regulation of homeostatic reactions. The existence and apparent redundancy of multiple pH surveillance systems attests to the concept that acid-base regulation is a vital issue for cell and tissue homeostasis. Since upregulation and overactivity of acid sensors appear to contribute to various forms of chronic pain, acid-sensitive ion channels and receptors are considered as targets for novel analgesic drugs. This approach will only be successful if the pathological implications of acid sensors can be differentiated pharmacologically from their physiological function.
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Affiliation(s)
- Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010, Graz, Austria.
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120
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Abstract
Chemogenomics is a modern approach to analysis of the biological effect of a wide array of small molecule compounds on a large set of homologous receptors or other macromolecular drug targets. However, the relative productivity of the method and the extremely high-cost procedure jointly force the scientist to use additional computational tools for rational compound library design and selection. The present chapter will focus specifically on application of a predictive mapping computational technology in the context of the fundamental principles of chemogenomic approach to foster rational drug design and derive information from the simultaneous biological evaluation of multiple compounds on a set of coherent biological targets.
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121
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Abstract
This review examines our developing understanding of the families and activities of some of the best known sensory-nerve-derived inflammatory neuropeptides, namely substance P, calcitonin gene-related peptide and galanin. Evidence to date shows involvement of these transmitters in a wide range of systems that includes roles as inflammatory modulators. There is an increasing understanding of the mechanisms involved in the release of the peptides from sensory nerves and these are key in understanding the potential of neuropeptides in modulating inflammatory responses and may also provide novel targets for anti-inflammatory therapy. The neuropeptides released act via specific G protein coupled receptors, most of which have now been cloned. There is knowledge of selective agonists and antagonists for many subtypes within these families. The study of neuropeptides in animal models has additionally revealed pathophysiological roles that in turn have led to the development of new drugs, based on selective receptor antagonism.
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Affiliation(s)
- Elizabeth S Fernandes
- Cardiovascular Division, King's College London, Franklin-Wilkins Building, Waterloo Campus, London SE1 9NH, UK
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122
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Di Gennaro P, Sestini R, Bacci S, Pacini A, Pinzani P, Domenici L, Toscano A, Massi D, Carli P, Genuardi M, Romagnoli P. Tacrolimus causes reduced GLI1 expression and phenotypic changes in the TE 354.T basal cell carcinoma cell line. J Dermatol Sci 2008; 54:52-4. [PMID: 19081230 DOI: 10.1016/j.jdermsci.2008.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 10/06/2008] [Accepted: 10/25/2008] [Indexed: 12/31/2022]
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123
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Denonne F. GPCRs in medicinal chemistry. IDrugs 2008; 11:870-875. [PMID: 19051146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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124
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Abstract
Regulatory T (Treg) cells are emerging as key players in the regulation of different immune responses, thereby representing potential candidates for therapeutic interventions in a broad variety of immunological disorders. While the reduction or loss in function would be of benefit during the treatment of cancer, induction and/or expansion of Treg cell function might be helpful to interfere with unwanted immune responses in transplantation medicine, during autoimmunity, allergy and inflammation. However, a better understanding of Treg cell biology is a prerequisite to specifically modulate its function during immune responses in vivo. In the present review we will discuss current concepts on different cell types, components and some novel surface receptors expressed by Treg cells, namely Neuropilin-1, CD83 and G protein-coupled receptor 83 which might represent promising targets for the modulation of Treg cell function in human disease.
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Affiliation(s)
- Wiebke Hansen
- Immunregulation Group, Institute of Medical Microbiology, University Hospital Essen, Hufelandstrasse 55, Essen, Germany.
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125
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Bernard J. Free fatty acid receptor family: novel targets for the treatment of diabetes and dyslipidemia. Curr Opin Investig Drugs 2008; 9:1078-1083. [PMID: 18821469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Free fatty acids (FFAs) fuel physiological processes in various tissues, such as skeletal muscle, the heart, liver and pancreas. Malfunction of FFA-mediated signaling pathways, as well as FFA metabolism, has been correlated to pathologies such as type 2 diabetes and dyslipidemia. The recent deorphanization of the FFA receptor family has drawn attention to these G-protein-coupled receptors as potential therapeutic targets for the treatment of metabolic diseases.
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Affiliation(s)
- Jerome Bernard
- Euroscreen SA, Rue Adrienne Bolland 47, 6041 Gosselies, Belgium.
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126
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Abstract
The G-protein-coupled receptors (GPCRs) are the largest known group of integral membrane receptor proteins and are the most common targets of pharmacotherapy. Mast cells (MCs) have been reported to play an important role in allergic diseases, such as urticaria and bronchial asthma. There is an increasing body of clinical evidence that MCs are recruited into allergic reactions by non-IgE-dependent mechanisms. Human MCs are activated and secrete histamine in response to neuropeptides, such as substance P and somatostatin, mediated by a GPCR, MRGX2. The microenvironment surrounding MCs in their resident tissues is likely to contain multiple factors that modify antigen-dependent MC activation. MCs express various GPCRs, and since the function of human MCs is modulated by various GPCR ligands, such as adenosine and sphingosine-1-phosphate, which are present in high levels in the bronchial alveolar lavage fluid of asthmatic patients, the GPCRs expressed on MCs may play an important role in human allergic diseases. The GPCRs expressed on MCs may serve as drug targets for the treatment of allergic diseases.
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Affiliation(s)
- Yoshimichi Okayama
- Division of Molecular Cell Immunology and Allergology, Advanced Medical Research Center, Nihon University Graduate School of Medical Science, Tokyo, Japan.
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127
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Snead AN, Miyakawa M, Tan ES, Scanlan TS. Trace amine-associated receptor 1 (TAAR1) is activated by amiodarone metabolites. Bioorg Med Chem Lett 2008; 18:5920-2. [PMID: 18752950 DOI: 10.1016/j.bmcl.2008.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 11/18/2022]
Abstract
Amiodarone (Cordarone, Wyeth-Ayerst Pharmaceuticals) is a clinically available drug used to treat a wide variety of cardiac arrhythmias. We report here the synthesis and characterization of a panel of potential amiodarone metabolites that have significant structural similarity to thyroid hormone and its metabolites the iodothyronamines. Several of these amiodarone derivatives act as specific agonists of the G protein-coupled receptor (GPCR) trace amine-associated receptor 1 (TAAR(1)). This result demonstrates a novel molecular target for amiodarone derivatives with potential clinical significance.
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Affiliation(s)
- Aaron N Snead
- Graduate Program in Chemistry and Chemical Biology, University of California at San Francisco, 600 16th Street, San Francisco, CA 94143, USA
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128
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Abstract
Obestatin is purported to be a peptide hormone encoded in preproghrelin. We studied the metabolic effects of continuous infusion of obestatin via subcutaneously implanted osmotic mini-pumps. Administration of up to 500nmol/kg body weight/day obestatin did not change 24h cumulative food intake or body weight in rats. Similarly, no effects were observed when obestatin was infused at 1000nmol/kg body weight/day for seven days. This dose of obestatin infused during a 24h fast did not alter weight loss, suggesting that obestatin has no effect on energy expenditure, and this dose did not alter glucose or insulin responses during an IPGTT. Obestatin was originally proposed to interact with GPR39 and subsequently the receptor for GLP-1. While both receptors are expressed in pancreatic islets, incubation with obestatin did not alter insulin release from islets in vitro. Moreover, obestatin did not bind to INS-1 beta-cells or HEK cells overexpressing GLP-1 receptors or displace GLP-1 binding to these cells. Our findings do not support the concept that obestatin is a hormone with metabolic actions.
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Affiliation(s)
- Suraj Unniappan
- Department of Cellular, Life Sciences Centre, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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129
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Nyan DC, Anbazhagan R, Hughes-Darden CA, Wachira SJM. Endosomal colocalization of melanocortin-3 receptor and beta-arrestins in CAD cells with altered modification of AKT/PKB. Neuropeptides 2008; 42:355-66. [PMID: 18291523 DOI: 10.1016/j.npep.2007.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 01/14/2023]
Abstract
The melanocortin 3-receptor is involved in regulating energy metabolism, body fluid composition and inflammatory responses. Melanocortin receptors function by activating membrane bound adenylate cyclase. However, the literature reports indicate that some G protein coupled receptors (GPCRs) can also activate mitogen activated protein kinase (MAPK) or phosphoinositide 3 kinase (PI3K) signaling pathways consequent to their endocytosis. These studies were undertaken to evaluate the role of these pathways in MC3R signaling in brain-stem neuronal cells. Recruitment of arrestins is implicated in the activation of secondary pathways by GPCRs and our data shows the colocalization of either arrestin B1 or B2 with MC3R in endosomes. An alteration in PKB phosphorylation pattern was observed in MC3R expressing cells independent of agonist stimulation. MC3R transfectants exhibited increased proliferation rates and inhibition of PKB pathway with triciribine abrogated cell proliferation in both vector control and MC3R transfectants. PKB is constitutively active in proliferating CAD cells but could be further activated by culturing the cells in differentiation medium. These studies suggest that the AKT/PKB pathway plays an important role in the proliferation of CAD cells and suggest a link between MC3R and cell growth pathways that may involve the alteration of AKT/PKB signaling pathway.
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Affiliation(s)
- D C Nyan
- Department of Biology, Morgan State University, Baltimore, MD 21251, USA
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130
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Cell-based assays in GPCR drug discovery. In this issue. Biotechnol J 2008; 3:430. [PMID: 18412181 DOI: 10.1002/biot.200890036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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131
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Hendriks-Balk MC, Peters SLM, Michel MC, Alewijnse AE. Regulation of G protein-coupled receptor signalling: focus on the cardiovascular system and regulator of G protein signalling proteins. Eur J Pharmacol 2008; 585:278-91. [PMID: 18410914 DOI: 10.1016/j.ejphar.2008.02.088] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 01/18/2008] [Accepted: 02/06/2008] [Indexed: 11/17/2022]
Abstract
G protein-coupled receptors (GPCRs) are involved in many biological processes. Therefore, GPCR function is tightly controlled both at receptor level and at the level of signalling components. Well-known mechanisms by which GPCR function can be regulated comprise desensitization/resensitization processes and GPCR up- and downregulation. GPCR function can also be regulated by several proteins that directly interact with the receptor and thereby modulate receptor activity. An additional mechanism by which receptor signalling is regulated involves an emerging class of proteins, the so-called regulators of G protein signalling (RGS). In this review we will describe some of these control mechanisms in more detail with some specific examples in the cardiovascular system. In addition, we will provide an overview on RGS proteins and the involvement of RGS proteins in cardiovascular function.
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Affiliation(s)
- Mariëlle C Hendriks-Balk
- Department Pharmacology and Pharmacotherapy, Academic Medical Center, Amsterdam, The Netherlands
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132
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Tanaka T, Yano T, Adachi T, Koshimizu TA, Hirasawa A, Tsujimoto G. Cloning and characterization of the rat free fatty acid receptor GPR120: in vivo effect of the natural ligand on GLP-1 secretion and proliferation of pancreatic beta cells. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:515-22. [PMID: 18320172 DOI: 10.1007/s00210-007-0250-y] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 12/12/2007] [Indexed: 02/06/2023]
Abstract
We have recently found that GPR120, which is abundantly expressed in intestine, functions as a receptor for unsaturated long-chain free fatty acids (FFAs) and that GPR120 stimulation promotes the secretion of glucagons-like peptide-1 (GLP-1) in the mouse (Hirasawa et al., Nat Med 11:90-94, 2005). In this study, we cloned and characterized rat GPR120 (rGPR120), and then we examined the in vivo effects of acute and long-term administration of the natural ligand alpha-linolenic acid (alpha-LA). The cloned rat GPR120 complimentary DNA had a seven transmembrane structure, and a homology comparison of human, mouse, and rat GPR120 revealed that the rat GPR120 (rGPR120) shares 85 and 98% sequence identity with the human and mouse GPR120 proteins, respectively. The tissue distribution and ligand properties of rGPR120 were similar to those of mouse GPR120. In addition, alpha-LA provoked a transient increase in [Ca2+]i levels in HEK293 cells expressing rGPR120. Furthermore, administration of alpha-LA to the rat increased plasma GLP-1 levels, and long-term administration of alpha-LA led to proliferation of pancreatic beta cells, probably because of the enhanced GLP-1 secretion. These results show that rat GPR120 is a G-protein-coupled receptor whose ligand is a free fatty acid, and it may play an important role in the FFA-associated physiological responses.
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Affiliation(s)
- Toshiki Tanaka
- Department of Genomic Drug Discovery Science, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
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133
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Milligan G. A day in the life of a G protein-coupled receptor: the contribution to function of G protein-coupled receptor dimerization. Br J Pharmacol 2008; 153 Suppl 1:S216-29. [PMID: 17965750 PMCID: PMC2268067 DOI: 10.1038/sj.bjp.0707490] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 08/21/2007] [Accepted: 09/06/2007] [Indexed: 02/07/2023] Open
Abstract
G protein-coupled receptors are one of the most actively studied families of proteins. However, despite the ubiquity of protein dimerization and oligomerization as a structural and functional motif in biology, until the last decade they were generally considered as monomeric, non-interacting polypeptides. For the metabotropic glutamate-like group of G protein-coupled receptors, it is now firmly established that they exist and function as dimers or, potentially, even within higher-order structures. Despite some evidence continuing to support the view that rhodopsin-like G protein-coupled receptors are predominantly monomers, many recent studies are consistent with the dimerization/oligomerization of such receptors. Key roles suggested for dimerization of G protein-coupled receptors include control of protein maturation and cell surface delivery and providing the correct framework for interactions with both hetero-trimeric G proteins and arrestins to allow signal generation and its termination. As G protein-coupled receptors are the most targeted group of proteins for the development of therapeutic small molecule medicines, recent indications that hetero-dimerization between co-expressed G protein-coupled receptors may be a common process offers the potential for the development of more selective and tissue restricted medicines. However, many of the key experiments have, so far, been limited to model cell systems. Priorities for the future include the generation of tools and reagents able to identify unequivocally potential G protein-coupled receptor hetero-dimers in native tissues and detailed analyses of the influence of hetero-dimerization on receptor function and pharmacology.
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Affiliation(s)
- G Milligan
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland, UK.
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134
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Romano A, McAlpine J, Ecker D. Post genomics - from antibody production to small molecule discovery. Curr Opin Drug Discov Devel 2008; 11:166-167. [PMID: 18283603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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135
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Strange PG. Signaling mechanisms of GPCR ligands. Curr Opin Drug Discov Devel 2008; 11:196-202. [PMID: 18283607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
G protein-coupled receptors constitute one of the major classes of drug targets, so understanding the mechanisms of signaling through these receptors is of great importance. This review covers some of the recent advances in G protein-coupled receptor signaling. A high resolution structure of the beta 2-adrenergic receptor has been reported, as well as several molecular switches involved in receptor activation. It has also been realised that receptors and G proteins and their subunits may not always separate upon receptor activation. The definition of the ability of these receptors to signal has been expanded considerably with the realisation that some signaling may occur independently of G proteins, that some signaling events may differ in their pharmacological profiles and that formation of heterodimers of these receptors may provide new avenues for both signaling and drug design.
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Affiliation(s)
- Philip G Strange
- School of Pharmacy, University of Reading, PO Box 228, Whiteknights, Reading, RG6 6AJ, UK.
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136
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Abstract
Presynaptic receptors for four families of neuropeptides will be discussed: opioids, neuropeptide Y, adrenocorticotropic hormone (ACTH), and orexins. Presynaptic receptors for the opioids (micro, delta, kappa, and ORL(1)) and neuropeptide Y (Y(2)) inhibit transmitter release from a variety of neurones, both in the peripheral and central nervous systems. These receptors, which were also identified in human tissue, are coupled to G(i/o) proteins and block voltage-dependent Ca(2+) channels, activate voltage-dependent K(+) channels, and/or interfere with the vesicle release machinery. Presynaptic receptors for ACTH (MC(2) receptors) have so far been identified almost exclusively in cardiovascular tissues from rabbits, where they facilitate noradrenaline release; they are coupled to G(s) protein and act via stimulation of adenylyl cyclase. Presynaptic receptors for orexins (most probably OX(2) receptors) have so far almost exclusively been identified in the rat and mouse brain, where they facilitate the release of glutamate and gamma-aminobutyric acid (GABA); they are most probably linked to G(q) and directly activate the vesicle release machinery or act via a transduction mechanism upstream of the release process. Agonists and antagonists at opioid receptors owe at least part of their therapeutic effects to actions on presynaptic receptors. Therapeutic drugs targeting neuropeptide Y and orexin receptors and presynaptic ACTH receptors so far are not available.
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MESH Headings
- Animals
- Humans
- Neuropeptides/metabolism
- Orexin Receptors
- Receptors, Corticotropin/drug effects
- Receptors, Corticotropin/metabolism
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Neuropeptide/drug effects
- Receptors, Neuropeptide/metabolism
- Receptors, Neuropeptide Y/drug effects
- Receptors, Neuropeptide Y/metabolism
- Receptors, Opioid/drug effects
- Receptors, Opioid/metabolism
- Receptors, Presynaptic/drug effects
- Receptors, Presynaptic/metabolism
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Affiliation(s)
- E Schlicker
- Institut für Pharmakologie und Toxikologie, Rheinische Friedrich-Wilhelms-Universität, Reuterstrasse 2b, 53113 Bonn, Germany.
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137
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Abstract
The central and peripheral nervous systems express multiple types of ligand and voltage-gated calcium channels (VGCCs), each with specific physiological roles and pharmacological and electrophysiological properties. The members of the Ca(v)2 calcium channel family are located predominantly at presynaptic nerve terminals, where they are responsible for controlling evoked neurotransmitter release. The activity of these channels is subject to modulation by a number of different means, including alternate splicing, ancillary subunit associations, peptide and small organic blockers, G-protein-coupled receptors (GPCRs), protein kinases, synaptic proteins, and calcium-binding proteins. These multiple and complex modes of calcium channel regulation allow neurons to maintain the specific, physiological window of cytoplasmic calcium concentrations which is required for optimal neurotransmission and proper synaptic function. Moreover, these varying means of channel regulation provide insight into potential therapeutic targets for the treatment of pathological conditions that arise from disturbances in calcium channel signaling. Indeed, considerable efforts are presently underway to identify and develop specific presynaptic calcium channel blockers that can be used as analgesics.
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Affiliation(s)
- Alexandra E Kisilevsky
- Hotchkiss Brain Institute and Department of Physiology and Biophysics, University of Calgary, Calgary, Canada
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138
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Abstract
Common G protein-coupled receptor (GPCR) gene variants that encode receptor proteins with a distinct sequence may alter drug efficacy without always resulting in a disease phenotype. GPCR genetic loci harbor numerous variants, such as DNA insertions or deletions and single-nucleotide polymorphisms that alter GPCR expression and function, thereby contributing to interindividual differences in disease susceptibility/progression and drug responses. In this chapter, these pharmacogenetic phenomena are reviewed with respect to a limited sampling of GPCR systems, including the beta(2)-adrenergic receptors, the cysteinyl leukotriene receptors, and the calcium-sensing receptor. In each example, the nature of the disruption to receptor function that results from each variant is discussed with respect to the regulation of gene expression, expression on cell surface (affected by receptor trafficking, dimerization, desensitization/downregulation), or perturbation of receptor function (by altering ligand binding, G protein coupling, and receptor constitutive activity). Despite the breadth of pharmacogenetic knowledge available, assessment for genetic variants is only occasionally applied to drug development projects involving pharmacogenomics or to optimizing the clinical use of GPCR drugs. The continued effort by the basic science of pharmacogenetics may draw the attention of drug discovery projects and clinicians alike to the utility of personalized pharmacogenomics as a means to optimize novel GPCR drug targets.
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Affiliation(s)
- Miles D Thompson
- Department of Laboratory Medicine and Pathobiology, Banting Institute, University of Toronto, Toronto, Ontario, Canada
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139
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Abstract
Interest has recently been rekindled in receptors that are activated by low molecular weight, noncatecholic, biogenic amines that are typically found as trace constituents of various vertebrate and invertebrate tissues and fluids. The timing of this resurgent focus on receptors activated by the "trace amines" (TA) beta-phenylethylamine (PEA), tyramine (TYR), octopamine (OCT), synephrine (SYN), and tryptamine (TRYP) is the direct result of 2 publications that appeared in 2001 describing the cloning of a novel G protein-coupled receptor (GPCR) referred to by their discoverers Borowsky et al. as TA1 and Bunzow et al. as TA receptor 1 (TAR1). When heterologously expressed in Xenopus laevis oocytes and various eukaryotic cell lines, recombinant rodent and human TAR dose-dependently couple to the stimulation of adenosine 3',5'-monophosphate (cAMP) production. Structure-activity profiling based on this functional response has revealed that in addition to the TA, other biologically active compounds containing a 2-carbon aliphatic side chain linking an amino group to at least 1 benzene ring are potent and efficacious TA receptor agonists with amphetamine (AMPH), methamphetamine, 3-iodothyronamine, thyronamine, and dopamine (DA) among the most notable. Almost 100 years after the search for TAR began, numerous TA1/TAR1-related sequences, now called TA-associated receptors (TAAR), have been identified in the genome of every species of vertebrate examined to date. Consequently, even though heterologously expressed TAAR1 fits the pharmacological criteria established for a bona fide TAR, a major challenge for those working in the field is to discern the in vivo pharmacology and physiology of each purported member of this extended family of GPCR. Only then will it be possible to establish whether TAAR1 is the family archetype or an iconoclast.
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Affiliation(s)
- David K Grandy
- Department of Physiology and Pharmacology, L334, School of Medicine, Oregon Health and Science University, Portland, OR 97239, United States.
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140
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Briddon SJ, Hill SJ. Pharmacology under the microscope: the use of fluorescence correlation spectroscopy to determine the properties of ligand-receptor complexes. Trends Pharmacol Sci 2007; 28:637-45. [PMID: 18001848 PMCID: PMC2148440 DOI: 10.1016/j.tips.2007.09.008] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Revised: 09/05/2007] [Accepted: 09/07/2007] [Indexed: 02/04/2023]
Abstract
Recent years have revealed a high degree of structural organisation in the way in which cell-surface receptors and their associated signalling complexes interact at a molecular level. Fluorescence-based techniques have been at the forefront of methodologies used to investigate this organisation and dissect the pharmacology of drug–receptor interactions at the single-cell level. One such technique, fluorescence correlation spectroscopy (FCS), in conjunction with a fluorescent ligand or receptor, is capable of providing quantitative information about the number of receptors and their mobilities within small areas of the cell membrane that approach the size of some signalling domains. This article describes the use of FCS to perform subcellular quantitative pharmacology, with particular reference to G-protein-coupled receptors (GPCRs). In conjunction with other forms of fluctuation analysis, such as two-colour cross-correlation FCS and molecular brightness analysis, FCS provides the first opportunity to investigate the domain-specific nature of GPCR pharmacology.
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141
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Ryan SD, Harris CS, Mo F, Lee H, Hou ST, Bazan NG, Haddad PS, Arnason JT, Bennett SAL. Platelet activating factor-induced neuronal apoptosis is initiated independently of its G-protein coupled PAF receptor and is inhibited by the benzoate orsellinic acid. J Neurochem 2007; 103:88-97. [PMID: 17877634 DOI: 10.1111/j.1471-4159.2007.04740.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bioactive lipid mediator platelet activating factor (PAF) is recognized as a key effecter of neuronal apoptosis, yet it is not clear whether its G-protein coupled receptor (PAFR) initiates or prevents PAF neurotoxicity. Using PAFR-/- and congenic wild-type mice, we show that PAF triggers caspase-3/7 activity and neuronal death in PAFR-/- but not PAFR+/+ cerebellar granule neurons. Restoring receptor expression by recombinant adenoviral infection protected cells from PAF challenge. Neuronal death was not mediated by nitric oxide or N-methyl-d-aspartate receptor signaling given that N-nitro-l-arginine methyl ester and MK-801 did not inhibit PAF-induced neuronal loss in PAFR-/- neurons. To intervene in PAFR-independent neurotoxicity, the anti-apoptotic actions of three structurally distinct PAF antagonists were compared to a panel of plant and fungal benzoic acid derivatives. We found that the PAF antagonist BN 52021 but not FR 49175 or CV 3988 inhibited PAFR-independent neurotoxicity. Orsellinic acid, a fungal-derived benzoic acid, blocked PAF-mediated neuronal apoptosis without affecting PAFR-mediated neuroprotection. These findings demonstrate that PAF can transduce apoptotic death in primary neurons independently of its G-protein coupled receptor, that PAFR activation is neuroprotective, and that orsellinic acid effectively attenuates PAFR-independent neuronal apoptosis.
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Affiliation(s)
- Scott D Ryan
- Department of Biochemistry, Microbiology, and Immunology, Neural Regeneration Laboratory and Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
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142
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O'Donnell LA, Agrawal A, Sabnekar P, Dichter MA, Lynch DR, Kolson DL. Apelin, an endogenous neuronal peptide, protects hippocampal neurons against excitotoxic injury. J Neurochem 2007; 102:1905-1917. [PMID: 17767704 DOI: 10.1111/j.1471-4159.2007.04645.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Several G protein-coupled receptors (GPCRs) mediate neuronal cell migration and survival upon activation by their native peptide ligands but activate death-signaling pathways when activated by certain non-native ligands. In cultured neurons, we recently described expression of the unique seven-transmembrane (7TM) -G protein-coupled receptor, APJ, which is also strongly expressed in neurons in the brain and various cell types in other tissues. We now demonstrate that the endogenous APJ peptide ligand apelin activates signaling pathways in rat hippocampal neurons and modulates neuronal survival. We found that (i) both APJ and apelin are expressed in hippocampal neurons; (ii) apelin peptides induce phosphorylation of the cell survival kinases AKT and Raf/ERK-1/2 in hippocampal neurons; and (iii) apelin peptides protect hippocampal neurons against NMDA receptor-mediated excitotoxicity, including that induced by human immunodeficiency virus type 1. Thus, apelin/APJ signaling likely represents an endogenous hippocampal neuronal survival response, and therefore apelin should be further investigated as a potential neuroprotectant against hippocampal injury.
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Affiliation(s)
- Lauren A O'Donnell
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USADivision of Pediatrics, University of Pennsylvania School of Medicine, and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Arpita Agrawal
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USADivision of Pediatrics, University of Pennsylvania School of Medicine, and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Praveena Sabnekar
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USADivision of Pediatrics, University of Pennsylvania School of Medicine, and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Marc A Dichter
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USADivision of Pediatrics, University of Pennsylvania School of Medicine, and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - David R Lynch
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USADivision of Pediatrics, University of Pennsylvania School of Medicine, and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Dennis L Kolson
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USADivision of Pediatrics, University of Pennsylvania School of Medicine, and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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143
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Abstract
Bioactive lysophospholipids (LPLs) are released by blood cells and can modulate many cellular activities such as angiogenesis and cell survival. In this study, the effects of sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) on excitability and exocytosis in bovine chromaffin cells were investigated using the whole-cell configuration of the patch-clamp. Voltage-gated Ca(2+) current was inhibited by S1P and LPA pre-treatment in a concentration-dependent manner with IC(50)s of 0.46 and 0.79 mumol/L, respectively. Inhibition was mostly reversible upon washout and prevented by suramin, an inhibitor of G-protein signaling. Na(+) current was inhibited by S1P, but not by LPA. However, recovery of Na(+) channels from inactivation was slowed by both LPLs. The outward K(+) current was also significantly reduced by both LPLs. Chromaffin cells fired repetitive action potentials in response to minimal injections of depolarizing current. Repetitive activity was dramatically reduced by LPLs. Consistent with the reduction in Ca(2+) current, exocytosis elicited by a train of depolarizations and the ensuing endocytosis were both inhibited by LPL pre-treatments. These data demonstrate the interaction between immune and endocrine systems mediated by the inhibitory effects of LPLs on the excitability of adrenal chromaffin cells.
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Affiliation(s)
- Chien-Yuan Pan
- Institute of Zoology, National Taiwan University, Taipei, Taiwan.
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144
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Chertkow Y, Weinreb O, Youdim MBH, Silver H. Gene expression changes in peripheral mononuclear cells from schizophrenic patients treated with a combination of antipsychotic with fluvoxamine. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:1356-62. [PMID: 17662512 DOI: 10.1016/j.pnpbp.2007.04.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 04/12/2007] [Accepted: 04/20/2007] [Indexed: 12/20/2022]
Abstract
Antipsychotic treatment combined with Selective Serotonin Reuptake Inhibitor (SSRI) antidepressant can improve negative symptoms in schizophrenic patients that are unresponsive to antipsychotic drugs alone. The mechanism of this therapeutic effect is not clear. The current study examined molecular changes induced by the combined treatment in human peripheral mononuclear cells (PMC) in order to get insight into its mechanism of action. Gene expression profile of PMC from antipsychotic-treated patients was examined before addition of the SSRI fluvoxamine, and 3 and 6 weeks after. Gene expression patterns screened with a cDNA array, comprising 1176 genes, revealed homologous changes in a range of transcripts related to G-protein coupled receptors (GPCR). Genes related to GPCR-family were assayed using customized cDNA array and the results verified by real-time RT-PCR. The mRNA expression of chemokine receptors, IL8RA and CCR1, and of RGS7 was significantly down-regulated following fluvoxamine augmentation. The clinical assessments showed improvement in negative symptoms following the combined treatment. The transcriptional analysis suggests that the therapeutic mechanism of the combined antipsychotic-fluvoxamine treatment may involve genes associated with G-protein coupled receptors (GPCR). Our findings suggest that gene expression changes in PMC may be useful in investigating the mechanism of drug action in schizophrenia.
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Affiliation(s)
- Yael Chertkow
- Molecular Neuropsychiatry Unit, Shaar Menashe Brain Behavior Laboratory, Shaar Menashe MHC, and Technion -- Faculty of Medicine, Haifa, Israel
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145
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Abstract
Neuroadaptations affecting dopamine transmission within the prefrontal cortex and striatum are thought to underlie relapse to cocaine seeking after extended periods of abstinence. Regulator of G-protein signaling 4 (RGS4) is a forebrain-enriched protein known to be dynamically regulated by dopamine receptors in response to acute psychostimulant administration. In this report, chronic noncontingent (cocaine binge) or response-contingent (self-administration) delivery of cocaine followed by 2-3 weeks of abstinence resulted in a decrease of RGS4 mRNA in the dorsal striatum and prefrontal cortex. Furthermore, re-exposure to the cocaine-associated context after abstinence renewed the drug seeking and restored the levels of RGS4 mRNA to control values. Changes in RGS4 mRNA levels might signal abnormal receptor G-protein coupling that impacts cocaine seeking.
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MESH Headings
- Animals
- Behavior, Addictive/genetics
- Behavior, Addictive/metabolism
- Behavior, Addictive/physiopathology
- Cocaine/pharmacology
- Cocaine-Related Disorders/genetics
- Cocaine-Related Disorders/metabolism
- Cocaine-Related Disorders/physiopathology
- Disease Models, Animal
- Dopamine/metabolism
- Dopamine Uptake Inhibitors/pharmacology
- Down-Regulation/drug effects
- Down-Regulation/physiology
- Drug Administration Schedule
- Male
- Neostriatum/drug effects
- Neostriatum/metabolism
- Neostriatum/physiopathology
- Prefrontal Cortex/drug effects
- Prefrontal Cortex/metabolism
- Prefrontal Cortex/physiopathology
- RGS Proteins/genetics
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine/metabolism
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/metabolism
- Recurrence
- Self Administration
- Substance Withdrawal Syndrome/genetics
- Substance Withdrawal Syndrome/metabolism
- Substance Withdrawal Syndrome/physiopathology
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Affiliation(s)
- Marek Schwendt
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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146
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Abstract
In this issue of the British Journal of Pharmacology, Ryberg et al. present convincing in vitro evidence that the orphan GPCR, GPR55, is a cannabinoid receptor. GPR55 was activated by a range of plant, synthetic and endogenous cannabinoids and blocked by the non-psychoactive phytocannabinoid, cannabidiol. Their experiments have revealed several differences between the pharmacology of GPR55 and the established cannabinoid CB1 and CB2 receptors. For example, the CB1 receptor antagonist, AM251, activated GPR55 and the main psychoactive constituent of cannabis, Delta9-tetrahydrocannabinol, displayed greater efficacy at GPR55 than at CB1 or CB2 receptors. They also compared the distribution of GPR55 and CB1 mRNA in mouse and report that GPR55 couples to Galpha13, that it is activated by virodhamine, palmitoylethanolamide and oleoylethanolamide, and that virodhamine displays relatively high efficacy as a GPR55 agonist. Still to be identified are the main roles played by GPR55 in health and disease and any potential therapeutic benefits of activating or blocking this receptor.
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Affiliation(s)
- R G Pertwee
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK.
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147
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Ryberg E, Larsson N, Sjögren S, Hjorth S, Hermansson NO, Leonova J, Elebring T, Nilsson K, Drmota T, Greasley PJ. The orphan receptor GPR55 is a novel cannabinoid receptor. Br J Pharmacol 2007; 152:1092-101. [PMID: 17876302 PMCID: PMC2095107 DOI: 10.1038/sj.bjp.0707460] [Citation(s) in RCA: 1101] [Impact Index Per Article: 64.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The endocannabinoid system functions through two well characterized receptor systems, the CB1 and CB2 receptors. Work by a number of groups in recent years has provided evidence that the system is more complicated and additional receptor types should exist to explain ligand activity in a number of physiological processes. EXPERIMENTAL APPROACH Cells transfected with the human cDNA for GPR55 were tested for their ability to bind and to mediate GTPgammaS binding by cannabinoid ligands. Using an antibody and peptide blocking approach, the nature of the G-protein coupling was determined and further demonstrated by measuring activity of downstream signalling pathways. KEY RESULTS We demonstrate that GPR55 binds to and is activated by the cannabinoid ligand CP55940. In addition endocannabinoids including anandamide and virodhamine activate GTPgammaS binding via GPR55 with nM potencies. Ligands such as cannabidiol and abnormal cannabidiol which exhibit no CB1 or CB2 activity and are believed to function at a novel cannabinoid receptor, also showed activity at GPR55. GPR55 couples to Galpha13 and can mediate activation of rhoA, cdc42 and rac1. CONCLUSIONS These data suggest that GPR55 is a novel cannabinoid receptor, and its ligand profile with respect to CB1 and CB2 described here will permit delineation of its physiological function(s).
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Affiliation(s)
- E Ryberg
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - N Larsson
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - S Sjögren
- Department of Medical Sciences, AstraZeneca R&D Mölndal, Sweden
| | - S Hjorth
- Department of Integrative PharmacologyAstraZeneca R&D Mölndal, Sweden
| | - N-O Hermansson
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - J Leonova
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - T Elebring
- Department of Medicinal Chemistry, AstraZeneca R&D Mölndal, Sweden
| | - K Nilsson
- Department of Medicinal Chemistry, AstraZeneca R&D Mölndal, Sweden
| | - T Drmota
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - P J Greasley
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
- Author for correspondence:
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148
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Deng BS, Nakamura A, Zhang W, Yanagisawa M, Fukuda Y, Kuwaki T. Contribution of orexin in hypercapnic chemoreflex: evidence from genetic and pharmacological disruption and supplementation studies in mice. J Appl Physiol (1985) 2007; 103:1772-9. [PMID: 17717124 DOI: 10.1152/japplphysiol.00075.2007] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously shown that hypercapnic chemoreflex in prepro-orexin knockout mice (ORX-KO) is attenuated during wake but not sleep periods. In that study, however, hypercapnic stimulation had been chronically applied for 6 h because of technical difficulty in changing the composition of the inspired gas mixture without distorting the animal's vigilance states. In the present study we examined possible involvement of orexin in acute respiratory chemoreflex during wake periods. Ventilation was recorded together with electroencephalography and electromyography before and after intracerebroventricular administration of orexin or an orexin receptor antagonist, SB-334867. A hypercapnic (5 or 10% CO(2)) or hypoxic (15 or 10% O(2)) gas mixture was introduced into the recording chamber for 5 min. Respiratory parameters were analyzed only for quiet wakefulness. When mice breathed normal room air, orexin-A and orexin-B but not vehicle or SB-334867 increased minute ventilation in both ORX-KO and wild-type (WT) mice. As expected, hypercapnic chemoreflex in vehicle-treated ORX- KO mice (0.22 +/- 0.03 mlxmin(-1)xg(-1)x% CO(2)(-1)) was significantly blunted compared with that in WT mice (0.51 +/- 0.05 mlxmin(-1)xg(-1)x% CO(2)(-1)). Supplementation of orexin-A or -B (3 nmol) partially restored the hypercapnic chemoreflex in ORX-KO mice (0.28 +/- 0.03 mlxmin(-1).g(-1)x% CO(2)(-1) for orexin-A and 0.32 +/- 0.04 mlxmin(-1)xg(-1)x% CO(2)(-1) for orexin-B). In addition, injection of SB-334867 (30 nmol) in WT mice decreased the hypercapnic chemoreflex (0.39 +/- 0.04 mlxmin(-1)xg(-1)x% CO(2)(-1)). On the other hand, hypoxic chemoreflex in vehicle-treated ORX-KO and SB-334867-treated WT mice was not different from that in corresponding controls. Our findings suggest that orexin plays a crucial role in CO(2) sensitivity at least during wake periods in mice.
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Affiliation(s)
- Ben-Shiang Deng
- Dept. of Molecular & Integrative Physiology, Chiba Univ. Graduate School of Medicine, 1-8-1 Chuo-ku, Chiba 260-8670, Japan
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149
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Eglen RM, Bosse R, Reisine T. Emerging concepts of guanine nucleotide-binding protein-coupled receptor (GPCR) function and implications for high throughput screening. Assay Drug Dev Technol 2007; 5:425-51. [PMID: 17638542 DOI: 10.1089/adt.2007.062] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Guanine nucleotide binding protein (G protein) coupled receptors (GPCRs) comprise one of the largest families of proteins in the human genome and are a target for 40% of all approved drugs. GPCRs have unique structural motifs that allow them to interact with a wide and diverse series of extracellular ligands, as well as intracellular proteins, G proteins, receptor activity-modifying proteins, arrestins, and indeed other receptors. This distinctive structure has led to numerous efforts to discover drugs against GPCRs with targeted therapeutic uses. Such "designer" drugs currently include allosteric regulators, inverse agonists, and drugs targeting hetero-oligomeric complexes. Moreover, the large family of orphan GPCRs provides a rich and novel field of targets to discover drugs with unique therapeutic properties. The numerous technologies to discover GPCR drugs have also greatly advanced over the years, facilitating compound screening against known and orphan GPCRs, as well as in the identification of unique designer GPCR drugs. Indeed, high throughput screening (HTS) technologies employing functional cell-based approaches are now widely used. These include measurement of second messenger accumulation such as cyclic AMP, calcium ions, and inositol phosphates, as well as mitogen-activated protein kinase activation, protein-protein interactions, and GPCR oligomerization. This review focuses on how the improved understanding of the molecular pharmacology of GPCRs, coupled with a plethora of novel HTS technologies, is leading to the discovery and development of an entirely new generation of GPCR-based therapeutics.
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Affiliation(s)
- Richard M Eglen
- Discovery and Research Reagents, PerkinElmer Life and Analytical Sciences, Waltham, MA 02451, USA.
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150
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Abstract
1 The rostral ventrolateral medulla (RVLM) is an essential vasomotor center in the brainstem which participates in maintaining resting levels of arterial pressure and for regulating baroreflex activity. We have demonstrated that microinjections of adrenomedullin (ADM), a vasoactive neuropeptide, into the RVLM cause increased resting mean arterial pressure (MAP) and heart rate (HR). However, the effect of ADM on baroreflex function remains unclear. 2 The purposes of the present study were to investigate the effect of ADM in the RVLM on the regulation of baroreflex activity and to identify the underlying mechanisms. Baroreflex curves were generated with intravenous injections of multiple doses of phenylephrine and nitroprusside. The upper and lower plateaus, reflex range, MAP at the midpoint of HR range (MAP(50)), and gain were evaluated before and after various microinjections were made into the RVLM of urethane-anesthetized rats. 3 Microinjections of ADM decreased the upper plateau, reflex range, and gain, and increased MAP(50), indicating that ADM in the RVLM impairs baroreflex function. 4 ADM(22-52), a putative ADM receptor antagonist, significantly increased the baroreflex gain and upper plateau, demonstrating that endogenous ADM tonically inhibits the baroreflex. Coinjections of ADM(22-52) with ADM blocked the ADM-induced baroreflex responses. 5 ADM's effect was abolished with H-89, a protein kinase A (PKA) inhibitor. 6 Our results show that ADM in the RVLM exerts an inhibitory effect on baroreflex activity via an ADM receptor-mediated mechanism, and that activation of PKA is involved in this event.
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Affiliation(s)
- Yong Xu
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada T6G 2H7.
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