201
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Histamine H3 receptors and their role in basal ganglia physiology and pathophysiology. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/sita.200700139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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202
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Herwig A, Ivanova EA, Lydon H, Barrett P, Steinlechner S, Loudon AS. Histamine H3 receptor and orexin A expression during daily torpor in the Djungarian hamster (Phodopus sungorus). J Neuroendocrinol 2007; 19:1001-7. [PMID: 18001330 DOI: 10.1111/j.1365-2826.2007.01620.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Seasonal animals use different strategies to reduce energy expenditure in the face of reduced seasonal food availability. For example, the ground squirrel enters a hibernation state with reduced metabolism, hypothermia and suppressed central nervous system activity, whereas the Djungarian hamster (Phodopus sungorus) employs daily bouts of torpor associated with reduced body temperature and energy expenditure. Studies in the hibernating ground squirrel implicate an increase in histamine synthesis and histamine H(3) receptor expression in the brain as a central mechanism governing hibernation. In the present study, we demonstrate an up-regulation of H(3) receptors in several brain nuclei in the Djungarian hamster during bouts of daily torpor, a shallow form of hypothermia, suggesting that histaminergic pathways may play a general role in maintaining low body temperature and torpor state in mammals. These regions include the arcuate nucleus, dorsomedial hypothalamus, suprachiasmatic nucleus, dorsal lateral geniculate nucleus and tuberomammillary nucleus. Interestingly, expression of the mRNA for orexins, a group of neuropeptides that increase wakefulness, remains unchanged during the arousal from daily torpor, suggesting that this classic 'arousal' pathway is not involved in the transition from a hypothermic to the euthermic state.
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Affiliation(s)
- A Herwig
- Institute of Zoology, University of Veterinary Medicine, Hannover, Germany
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203
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Altenbach RJ, Liu H, Banfor PN, Browman KE, Fox GB, Fryer RM, Komater VA, Krueger KM, Marsh K, Miller TR, Pan JB, Pan L, Sun M, Thiffault C, Wetter J, Zhao C, Zhou D, Esbenshade TA, Hancock AA, Cowart MD. Synthesis, Potency, and In Vivo Profiles of Quinoline Containing Histamine H3 Receptor Inverse Agonists. J Med Chem 2007; 50:5439-48. [DOI: 10.1021/jm0705051] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Robert J. Altenbach
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Huaqing Liu
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Patricia N. Banfor
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Kaitlin E. Browman
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Gerard B. Fox
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Ryan M. Fryer
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Victoria A. Komater
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Kathleen M. Krueger
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Kennan Marsh
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Thomas R. Miller
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Jia Bao Pan
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Liping Pan
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Minghua Sun
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Christine Thiffault
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Jill Wetter
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Chen Zhao
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Deliang Zhou
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Timothy A. Esbenshade
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Arthur A. Hancock
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
| | - Marlon D. Cowart
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6123
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204
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Bongers G, Krueger KM, Miller TR, Baranowski JL, Estvander BR, Witte DG, Strakhova MI, van Meer P, Bakker RA, Cowart MD, Hancock AA, Esbenshade TA, Leurs R. An 80-amino acid deletion in the third intracellular loop of a naturally occurring human histamine H3 isoform confers pharmacological differences and constitutive activity. J Pharmacol Exp Ther 2007; 323:888-98. [PMID: 17855474 DOI: 10.1124/jpet.107.127639] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this article, we pharmacologically characterized two naturally occurring human histamine H3 receptor (hH3R) isoforms, hH3R(445) and hH3R(365). These abundantly expressed splice variants differ by a deletion of 80 amino acids in the intracellular loop 3. In this report, we show that the hH3R(365) is differentially expressed compared with the hH3R(445) and has a higher affinity and potency for H3R agonists and conversely a lower potency and affinity for H3R inverse agonists. Furthermore, we show a higher constitutive signaling of the hH3R(365) compared with the hH3R(445) in both guanosine-5'-O-(3-[35S]thio) triphosphate binding and cAMP assays, likely explaining the observed differences in hH3R pharmacology of the two isoforms. Because H3R ligands are beneficial in animal models of obesity, epilepsy, and cognitive diseases such as Alzheimer's disease and attention deficit hyperactivity disorder and currently entered clinical trails, these differences in H3R pharmacology of these two isoforms are of great importance for a detailed understanding of the action of H3R ligands.
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Affiliation(s)
- Gerold Bongers
- Leiden/Amsterdam Center for Drug Research, Department of Medicinal Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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205
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Wijtmans M, Leurs R, de Esch I. Histamine H3 receptor ligands break ground in a remarkable plethora of therapeutic areas. Expert Opin Investig Drugs 2007; 16:967-85. [PMID: 17594183 DOI: 10.1517/13543784.16.7.967] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The neurotransmitter histamine exerts its action through four distinct histamine receptors. The histamine H(1) and H(2) receptor are well established drug targets, whereas the histamine H(4) receptor is undergoing rigorous characterisation at present. The histamine H(3) receptor (H(3)R) is a G(i/o)-protein coupled receptor and is mostly expressed in the CNS. A remarkably large and different array of therapeutic areas, in which ligands for the H(3)R may prove useful, has been identified and a massive research undertaking is underway to substantiate the high expectations for H(3)R ligands. At present, several ligands for the H(3)R are being evaluated in clinical studies. In this review, the many potential therapeutic areas for H(3)R antagonists, inverse agonists and agonists is discussed. Promising medicinal chemistry and toxicological developments, as well as the advancement of several H(3)R ligands into the clinic, will be highlighted. This review also describes the problems that have been overcome and the questions that remain in developing H(3)R-related drugs. Considering the tremendous efforts by industry, it can be expected that the first H(3)R drugs will reach the market soon.
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Affiliation(s)
- Maikel Wijtmans
- Vrije Universiteit Amsterdam, Leiden/Amsterdam Center of Drug Research, Division of Medicinal Chemistry, Faculty of Sciences, De Boelelaan 1083, Amsterdam, The Netherlands
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206
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Bosier B, Hermans E. Versatility of GPCR recognition by drugs: from biological implications to therapeutic relevance. Trends Pharmacol Sci 2007; 28:438-46. [PMID: 17629964 DOI: 10.1016/j.tips.2007.06.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 05/22/2007] [Accepted: 06/26/2007] [Indexed: 01/13/2023]
Abstract
Most drugs acting on G-protein-coupled receptors (GPCRs) are classically defined as agonists, partial agonists or antagonists. This simplified classification seems sufficient to explain most of their therapeutic properties. The more recent description of inverse agonism has helped to revise theoretical models of GPCR function, but the therapeutic implications of the new concepts remain clearly restricted. Further complexity has arisen with demonstrations that a given receptor can adopt various conformations that support coupling with distinct G proteins. Because the related signaling pathways seem to be differentially affected by some ligands, the concept of 'functional selectivity' has been proposed, calling for a revision of the definitions of agonism and intrinsic efficacy. Evidence of complexity in G-protein coupling and examples of functional selectivity are accumulating, opening perspectives for drug development. Although such complexity should be regarded as an opportunity to gain pharmacological specificity, unraveling the physiological implications of these concepts is essential before their therapeutic relevance can be defined.
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Affiliation(s)
- Barbara Bosier
- Unité de Chimie Pharmaceutique et de Radiopharmacie (UCL 7340), Université Catholique de Louvain, B-1200 Brussels, Belgium
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207
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Bongers G, Sallmen T, Passani MB, Mariottini C, Wendelin D, Lozada A, Marle AV, Navis M, Blandina P, Bakker RA, Panula P, Leurs R. The Akt/GSK-3beta axis as a new signaling pathway of the histamine H(3) receptor. J Neurochem 2007; 103:248-58. [PMID: 17623045 DOI: 10.1111/j.1471-4159.2007.04752.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Drugs targeting the histamine H(3) receptor (H(3)R) are suggested to be beneficial for the treatment of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease. The H(3)R activates G(i/o)-proteins to inhibit adenylyl cyclase activity and modulates phospholipase A(2) and MAPK activity. Herein we show that, in transfected SK-N-MC cells, the H(3)R modulates the activity of the Akt/Glycogen synthase kinase 3beta (GSK-3beta) axis both in a constitutive and agonist-dependent fashion. H(3)R stimulation with the H(3)R agonist immepip induces the phosphorylation of both Ser473 and Thr308 on Akt, a serine/threonine kinase that is important for neuronal development and function. The H(3)R-mediated activation of Akt can be inhibited by the H(3)R inverse agonist thioperamide, and by Wortmannin, LY294002 and PTX, suggesting the observed Akt activation occurs via a G(i/o)-mediated activation of phosphoinositide-3-kinase. H(3)R activation also results in the phosphorylation of Ser9 on GSK-3beta, which acts downstream of Akt and has a prominent role in brain function. In addition, we show the H(3)R-mediated phosphorylation of Akt at Ser473 to occur in primary rat cortical neurons and in rat brain slices. The discovery of this signaling property of the H(3)R adds new understanding to the roles of histamine and the H(3)R in brain function and pathology.
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Affiliation(s)
- Gerold Bongers
- Leiden/Amsterdam Center for Drug Research, Department of Medicinal Chemistry, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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208
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Arrang JM. Le récepteur H3 de l’histamine : une cible pour de nouveaux traitements des troubles de l’éveil et de la cognition. ANNALES PHARMACEUTIQUES FRANÇAISES 2007; 65:275-84. [PMID: 17652997 DOI: 10.1016/s0003-4509(07)90047-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The histamine H3 receptor was identified in the 80's by our group as a presynaptic autoreceptor inhibiting histamine synthesis and release in the rat brain. Sixteen years later, cloning of the related human H3 receptor revealed the existence of isoforms, species pharmacological differences and a high constitutive (spontaneous) activity of the receptor. All these molecular findings have to be taken into account for optimizing aimed at clinical applications ligands. H3 receptor inverse agonists, by increasing histamine neuron activity, promote arousal and enhance cognitive performances. Pharmaceutical firms have shown considerable interest for this new class of drugs and many programmes of clinical development of H3 receptor inverse agonists for the treatment of arousal and cognitive disorders are presently being conducted.
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Affiliation(s)
- J-M Arrang
- Inserm, Unité de neurobiologie et pharmacologie moléculaire (U 573), Centre Paul Broca, 2 ter, rue d'Alésia F 75014 Paris.
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209
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Arrang JM, Morisset S, Gbahou F. Constitutive activity of the histamine H3 receptor. Trends Pharmacol Sci 2007; 28:350-7. [PMID: 17573125 DOI: 10.1016/j.tips.2007.05.002] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 04/12/2007] [Accepted: 05/25/2007] [Indexed: 11/27/2022]
Abstract
Constitutive activity has been mainly recorded for numerous overexpressed and/or mutated receptors. The histamine H(3) receptor (H(3)R) is a target of choice to study the physiological relevance of this process. In rodent brain, postsynaptic H(3)Rs show high constitutive activity, and presynaptic H(3) autoreceptors that show constitutive activity have a predominant role in inhibiting the activity of histamine neurons. H(3)R inverse agonists abrogate this constitutive brake and enhance histamine release in vivo. Some of these inverse agonists have entered clinical trials for the treatment of cognitive and food intake disorders. Studies performed in vitro and in vivo with proxyfan show that this H(3)R ligand is a 'protean agonist' - that is, a ligand with a spectrum of activity ranging from full agonism to full inverse agonism depending on the level of H(3)R constitutive activity. Consistent with its physiological and therapeutic relevance, the constitutive activity of H(3)R thus has a major function in the brain and regulates the activity of H(3)R-targeted drugs.
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Affiliation(s)
- Jean-Michel Arrang
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U 573), Centre Paul Broca, 75014 Paris, France.
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210
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Bonaventure P, Letavic M, Dugovic C, Wilson S, Aluisio L, Pudiak C, Lord B, Mazur C, Kamme F, Nishino S, Carruthers N, Lovenberg T. Histamine H3 receptor antagonists: From target identification to drug leads. Biochem Pharmacol 2007; 73:1084-96. [PMID: 17129577 DOI: 10.1016/j.bcp.2006.10.031] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 10/19/2006] [Accepted: 10/31/2006] [Indexed: 11/22/2022]
Abstract
The successful cloning and functional expression of the histamine H(3) receptor in the late 1990 s has greatly facilitated our efforts to identify small molecule, non-imidazole based compounds to permit the evaluation of H(3) antagonists in models of CNS disorders. High-throughput screening identified several series of lead compounds, including a series of imidazopyridines, which led to JNJ-6379490, a compound with high affinity for the human H(3) receptor. Analysis of structural features common to several series of non-imidazole H(3) receptor ligands resulted in a pharmacophore model. This model led to the design of JNJ-5207852, a diamine-based H(3) antagonist with good in vitro and in vivo efficacy but with an undesirable long half-life. However, further modifications of the template provided an understanding of the effect of structural modifications on pharmacokinetic properties, ultimately affording several additional series of compounds including JNJ-10181457, a compound with an improved pharmacokinetic profile. These compounds allowed in vivo pharmacological evaluation to show that H(3) antagonists promote wakefulness, but unlike modafinil and classical psychostimultants, they do not increase locomotor activity or produce any alteration of the EEG power spectral activity in rats. H(3) antagonists also increase extracellular acetylcholine and norepinephrine but not dopamine in rat frontal cortex and show efficacy in various models of learning-memory deficit. In addition, cFos immunoreactivity studies show H(3) antagonists activate neuronal cells in restricted rat brain regions in contrast to widespread activation after modafinil or amphetamine treatment. Therefore, H(3) antagonists are promising clinical candidates for the treatment of excessive day time sleepiness and/or cognitive disorders.
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Affiliation(s)
- P Bonaventure
- Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA.
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211
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Medhurst AD, Briggs MA, Bruton G, Calver AR, Chessell I, Crook B, Davis JB, Davis RP, Foley AG, Heslop T, Hirst WD, Medhurst SJ, Ociepka S, Ray A, Regan CM, Sargent B, Schogger J, Stean TO, Trail BK, Upton N, White T, Orlek B, Wilson DM. Structurally novel histamine H3 receptor antagonists GSK207040 and GSK334429 improve scopolamine-induced memory impairment and capsaicin-induced secondary allodynia in rats. Biochem Pharmacol 2007; 73:1182-94. [PMID: 17276409 DOI: 10.1016/j.bcp.2007.01.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 12/13/2006] [Accepted: 01/03/2007] [Indexed: 11/25/2022]
Abstract
GSK207040 (5-[(3-cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-N-methyl-2-pyrazinecarboxamide) and GSK334429 (1-(1-methylethyl)-4-({1-[6-(trifluoromethyl)-3-pyridinyl]-4-piperidinyl}carbonyl)hexahydro-1H-1,4-diazepine) are novel and selective non-imidazole histamine H(3) receptor antagonists from distinct chemical series with high affinity for human (pK(i)=9.67+/-0.06 and 9.49+/-0.09, respectively) and rat (pK(i)=9.08+/-0.16 and 9.12+/-0.14, respectively) H(3) receptors expressed in cerebral cortex. At the human recombinant H(3) receptor, GSK207040 and GSK334429 were potent functional antagonists (pA(2)=9.26+/-0.04 and 8.84+/-0.04, respectively versus H(3) agonist-induced changes in cAMP) and exhibited inverse agonist properties (pIC(50)=9.20+/-0.36 and 8.59+/-0.04 versus basal GTPgammaS binding). Following oral administration, GSK207040 and GSK334429 potently inhibited cortical ex vivo [(3)H]-R-alpha-methylhistamine binding (ED(50)=0.03 and 0.35 mg/kg, respectively). Functional antagonism of central H(3) receptors was demonstrated by blockade of R-alpha-methylhistamine-induced dipsogenia in rats (ID(50)=0.02 and 0.11 mg/kg p.o. for GSK207040 and GSK334429, respectively). In more pathophysiologically relevant pharmacodynamic models, GSK207040 (0.1, 0.3, 1 and 3mg/kg p.o.) and GSK334429 (0.3, 1 and 3mg/kg p.o.) significantly reversed amnesia induced by the cholinergic antagonist scopolamine in a passive avoidance paradigm. In addition, GSK207040 (0.1, 0.3 and 1mg/kg p.o.) and GSK334429 (3 and 10mg/kg p.o.) significantly reversed capsaicin-induced reductions in paw withdrawal threshold, suggesting for the first time that blockade of H(3) receptors may be able to reduce tactile allodynia. Novel H(3) receptor antagonists such as GSK207040 and GSK334429 may therefore have therapeutic potential not only in dementia but also in neuropathic pain.
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Affiliation(s)
- Andrew D Medhurst
- Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline, Third Avenue, Harlow, Essex CM19 5AW, UK.
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212
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Bongers G, Bakker RA, Leurs R. Molecular aspects of the histamine H3 receptor. Biochem Pharmacol 2007; 73:1195-204. [PMID: 17276412 DOI: 10.1016/j.bcp.2007.01.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 11/27/2006] [Accepted: 01/03/2007] [Indexed: 11/19/2022]
Abstract
The cloning of the histamine H(3) receptor (H(3)R) cDNA in 1999 by Lovenberg et al. [10] allowed detailed studies of its molecular aspects and indicated that the H(3)R can activate several signal transduction pathways including G(i/o)-dependent inhibition of adenylyl cyclase, activation of phospholipase A(2), Akt and the mitogen activated kinase as well as the inhibition of the Na(+)/H(+) exchanger and inhibition of K(+)-induced Ca(2+) mobilization. Moreover, cloning of the H(3)R has led to the discovery several H(3)R isoforms generated through alternative splicing of the H(3)R mRNA. The H(3)R has gained the interest of many pharmaceutical companies as a potential drug target for the treatment of various important disorders like obesity, myocardial ischemia, migraine, inflammatory diseases and several CNS disorders like Alzheimer's disease, attention-deficit hyperactivity disorder and schizophrenia. In this paper, we review various molecular aspects of the hH(3)R including its signal transduction, dimerization and the occurrence of different H(3)R isoforms.
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Affiliation(s)
- Gerold Bongers
- Leiden/Amsterdam Center for Drug Research, Department of Medicinal Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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213
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Peitsaro N, Sundvik M, Anichtchik OV, Kaslin J, Panula P. Identification of zebrafish histamine H1, H2 and H3 receptors and effects of histaminergic ligands on behavior. Biochem Pharmacol 2007; 73:1205-14. [PMID: 17266939 DOI: 10.1016/j.bcp.2007.01.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 12/07/2006] [Accepted: 01/08/2007] [Indexed: 01/28/2023]
Abstract
Neuronal histamine regulates several functions in the vertebrate brain. The zebrafish brain contains a widespread histaminergic system and H(3) receptor ligand binding has been reported. In this study we provide evidence for the existence of histamine H(1), H(2) and H(3) receptor genes in zebrafish. Single copies of putative histamine H(1), H(2) and H(3) receptors were identified and cloned from the zebrafish brain. Expression analysis suggested that they are expressed in the brain and a few other tissues. Widespread distribution of zebrafish H(2) receptor binding sites was detected with [(125)I]iodoaminopotentidine in brain sections. Zebrafish larvae were exposed to 1, 10 or 100 microM of the H(1) ligand pyrilamine, the H(2) ligand cimetidine and the H(3) ligands thioperamide and immepip for 5 days. Significant decreases in swimming distance were observed with the highest dose of all ligands, whereas cimetidine gave a significant decrease also with 1 and 10 microM doses. These results provide the first molecular biological evidence for the presence of histamine receptors in zebrafish. These histamine receptors resemble those of higher vertebrates and they provide a useful model for pharmacological and behavioral studies for characterizing the functions of histamine in more detail.
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Affiliation(s)
- Nina Peitsaro
- Neuroscience Center, Institute of Biomedicine/Anatomy, Haartmaninkatu 8, 00014 University of Helsinki, Finland
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214
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Nelson CP, Challiss RAJ. “Phenotypic” pharmacology: The influence of cellular environment on G protein-coupled receptor antagonist and inverse agonist pharmacology. Biochem Pharmacol 2007; 73:737-51. [PMID: 17046719 DOI: 10.1016/j.bcp.2006.09.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 08/31/2006] [Accepted: 09/06/2006] [Indexed: 11/25/2022]
Abstract
A central dogma of G protein-coupled receptor (GPCR) pharmacology has been the concept that unlike agonists, antagonist ligands display equivalent affinities for a given receptor, regardless of the cellular environment in which the affinity is assayed. Indeed, the widespread use of antagonist pharmacology in the classification of receptor expression profiles in vivo has relied upon this 'antagonist assumption'. However, emerging evidence suggests that the same gene-product may exhibit different antagonist pharmacological profiles, depending upon the cellular context in which it is expressed-so-called 'phenotypic' profiles. In this commentary, we review the evidence relating to some specific examples, focusing on adrenergic and muscarinic acetylcholine receptor systems, where GPCR antagonist/inverse agonist pharmacology has been demonstrated to be cell- or tissue-dependent, before going on to examine some of the ways in which the cellular environment might modulate receptor pharmacology. In the majority of cases, the cellular factors responsible for generating phenotypic profiles are unknown, but there is substantial evidence that factors, including post-transcriptional modifications, receptor oligomerization and constitutive receptor activity, can influence GPCR pharmacology and these concepts are discussed in relation to antagonist phenotypic profiles. A better molecular understanding of the impact of cell background on GPCR antagonist pharmacology is likely to provide previously unrealized opportunities to achieve greater specificity in new drug discovery candidates.
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Affiliation(s)
- Carl P Nelson
- Department of Cell Physiology & Pharmacology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK.
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215
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Acevedo SF, de Esch IJP, Raber J. Sex- and histamine-dependent long-term cognitive effects of methamphetamine exposure. Neuropsychopharmacology 2007; 32:665-72. [PMID: 16710318 DOI: 10.1038/sj.npp.1301091] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
As prenatal methamphetamine (MA) exposure results in long-term hippocampus-dependent cognitive deficits, the increased MA use in women of childbearing age is of great concern. As mice are most commonly used in genetic models, we started to study the potential effects of neonatal MA exposure in female and male mice on brain function 3 months later. As histamine (HA) might mediate some effects of MA in adulthood, we also tested whether in neonates HA might mediate the long-term effects of MA using HA H(3) receptor agonists and antagonists. Stimulation of HA H(3) receptors by H(3) agonists inhibits HA synthesis and release, whereas inhibition of H(3) receptors by H(3) receptor antagonists increases HA release. MA (5 mg/kg), the H(3) receptor antagonist thioperamide (5 mg/kg), and the H(3) receptor agonist immepip (5 mg/kg) alone or in the presence of MA (5 mg/kg) were administered once daily from postnatal days 11 to 20 and the mice were tested at 3 months of age. Here we show that in mice exposure to MA early in life causes sex-dependent impairments in object recognition, spatial learning, and memory in the water maze, and pre-pulse inhibition in adulthood. HA mediates these impairments. Increasing HA release mimicked, whereas inhibiting HA release blocked the long-term detrimental MA effects. This model could be used to determine the role of genetic and environmental factors in MA-dependent cognitive impairments and to develop therapeutic strategies to inhibit them.
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Affiliation(s)
- Summer F Acevedo
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR 97239, USA
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216
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Black LA, Nersesian DL, Sharma P, Ku YY, Bennani YL, Marsh KC, Miller TR, Esbenshade TA, Hancock AA, Cowart M. 4-[6-(2-Aminoethyl)naphthalen-2-yl]benzonitriles are potent histamine H3 receptor antagonists with high CNS penetration. Bioorg Med Chem Lett 2007; 17:1443-6. [PMID: 17169555 DOI: 10.1016/j.bmcl.2006.11.073] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 11/16/2006] [Accepted: 11/29/2006] [Indexed: 10/23/2022]
Abstract
4-[6-(2-Tertiaryaminoethyl)naphthalen-2-yl]benzonitriles are conformationally constrained histamine H3 receptor antagonists with high potency and selectivity. The analogs were designed around a naphthalene core, with the goal of enhancing lipophilicity and CNS penetration, as compared to a previously reported benzofuran series. The SAR of the tertiary amine moiety is similar to that reported for the benzofuran series, with analogs bearing a 2-methylpyrrolidine substituent possessing the greatest rat and human H3 receptor binding affinities.
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Affiliation(s)
- Lawrence A Black
- Neuroscience Research, GPRD, Abbott Laboratories, Abbott Park, IL 60064, USA.
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217
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Medhurst AD, Atkins AR, Beresford IJ, Brackenborough K, Briggs MA, Calver AR, Cilia J, Cluderay JE, Crook B, Davis JB, Davis RK, Davis RP, Dawson LA, Foley AG, Gartlon J, Gonzalez MI, Heslop T, Hirst WD, Jennings C, Jones DNC, Lacroix LP, Martyn A, Ociepka S, Ray A, Regan CM, Roberts JC, Schogger J, Southam E, Stean TO, Trail BK, Upton N, Wadsworth G, Wald JA, White T, Witherington J, Woolley ML, Worby A, Wilson DM. GSK189254, a Novel H3 Receptor Antagonist That Binds to Histamine H3 Receptors in Alzheimer's Disease Brain and Improves Cognitive Performance in Preclinical Models. J Pharmacol Exp Ther 2007; 321:1032-45. [PMID: 17327487 DOI: 10.1124/jpet.107.120311] [Citation(s) in RCA: 238] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
6-[(3-Cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-N-methyl-3-pyridinecarboxamide hydrochloride (GSK189254) is a novel histamine H(3) receptor antagonist with high affinity for human (pK(i) = 9.59 -9.90) and rat (pK(i) = 8.51-9.17) H(3) receptors. GSK189254 is >10,000-fold selective for human H(3) receptors versus other targets tested, and it exhibited potent functional antagonism (pA(2) = 9.06 versus agonist-induced changes in cAMP) and inverse agonism [pIC(50) = 8.20 versus basal guanosine 5'-O-(3-[(35)S]thio)triphosphate binding] at the human recombinant H(3) receptor. In vitro autoradiography demonstrated specific [(3)H]GSK189254 binding in rat and human brain areas, including cortex and hippocampus. In addition, dense H(3) binding was detected in medial temporal cortex samples from severe cases of Alzheimer's disease, suggesting for the first time that H(3) receptors are preserved in late-stage disease. After oral administration, GSK189254 inhibited cortical ex vivo R-(-)-alpha-methyl[imidazole-2,5(n)-(3)H]histamine dihydrochloride ([(3)H]R-alpha-methylhistamine) binding (ED(50) = 0.17 mg/kg) and increased c-Fos immunoreactivity in prefrontal and somatosensory cortex (3 mg/kg). Microdialysis studies demonstrated that GSK189254 (0.3-3 mg/kg p.o.) increased the release of acetylcholine, noradrenaline, and dopamine in the anterior cingulate cortex and acetylcholine in the dorsal hippocampus. Functional antagonism of central H(3) receptors was demonstrated by blockade of R-alpha-methylhistamine-induced dipsogenia in rats (ID(50) = 0.03 mg/kg p.o.). GSK189254 significantly improved performance of rats in diverse cognition paradigms, including passive avoidance (1 and 3 mg/kg p.o.), water maze (1 and 3 mg/kg p.o.), object recognition (0.3 and 1 mg/kg p.o.), and attentional set shift (1 mg/kg p.o.). These data suggest that GSK189254 may have therapeutic potential for the symptomatic treatment of dementia in Alzheimer's disease and other cognitive disorders.
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Affiliation(s)
- Andrew D Medhurst
- Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline, Third Ave., Harlow, Essex, CM19 5AW, UK.
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218
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Smit MJ, Vischer HF, Bakker RA, Jongejan A, Timmerman H, Pardo L, Leurs R. Pharmacogenomic and Structural Analysis of Constitutive G Protein–Coupled Receptor Activity. Annu Rev Pharmacol Toxicol 2007; 47:53-87. [PMID: 17029567 DOI: 10.1146/annurev.pharmtox.47.120505.105126] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) respond to a chemically diverse plethora of signal transduction molecules. The notion that GPCRs also signal without an external chemical trigger, i.e., in a constitutive or spontaneous manner, resulted in a paradigm shift in the field of GPCR pharmacology. The discovery of constitutive GPCR activity and the fact that GPCR binding and signaling can be strongly affected by a single point mutation drew attention to the evolving area of GPCR pharmacogenomics. For a variety of GPCRs, point mutations have been convincingly linked to human disease. Mutations within conserved motifs, known to be involved in GPCR activation, might explain the properties of some naturally occurring, constitutively active GPCR variants linked to disease. In this review, we provide a brief historical introduction to the concept of constitutive receptor activity and the pharmacogenomic and structural aspects of constitutive receptor activity.
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Affiliation(s)
- Martine J Smit
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Vrije Universiteit, Faculty of Sciences, Department of Chemistry, 1081 HV Amsterdam, The Netherlands.
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219
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Levi R, Seyedi N, Schaefer U, Estephan R, Mackins CJ, Tyler E, Silver RB. Histamine H3-receptor signaling in cardiac sympathetic nerves: Identification of a novel MAPK-PLA2-COX-PGE2-EP3R pathway. Biochem Pharmacol 2007; 73:1146-56. [PMID: 17266940 PMCID: PMC1893009 DOI: 10.1016/j.bcp.2007.01.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 12/12/2006] [Accepted: 01/03/2007] [Indexed: 01/08/2023]
Abstract
We hypothesized that the histamine H(3)-receptor (H(3)R)-mediated attenuation of norepinephrine (NE) exocytosis from cardiac sympathetic nerves results not only from a Galpha(i)-mediated inhibition of the adenylyl cyclase-cAMP-PKA pathway, but also from a Gbetagamma(i)-mediated activation of the MAPK-PLA(2) cascade, culminating in the formation of an arachidonate metabolite with anti-exocytotic characteristics (e.g., PGE(2)). We report that in Langendorff-perfused guinea-pig hearts and isolated sympathetic nerve endings (cardiac synaptosomes), H(3)R-mediated attenuation of K(+)-induced NE exocytosis was prevented by MAPK and PLA(2) inhibitors, and by cyclooxygenase and EP(3)-receptor (EP(3)R) antagonists. Moreover, H(3)R activation resulted in MAPK phosphorylation in H(3)R-transfected SH-SY5Y neuroblastoma cells, and in PLA(2) activation and PGE(2) production in cardiac synaptosomes; H(3)R-induced MAPK phosphorylation was prevented by an anti-betagamma peptide. Synergism between H(3)R and EP(3)R agonists (i.e., imetit and sulprostone, respectively) suggested that PGE(2) may be a downstream effector of the anti-exocytotic effect of H(3)R activation. Furthermore, the anti-exocytotic effect of imetit and sulprostone was potentiated by the N-type Ca(2+)-channel antagonist omega-conotoxin GVIA, and prevented by an anti-Gbetagamma peptide. Our findings imply that an EP(3)R Gbetagamma(i)-induced decrease in Ca(2+) influx through N-type Ca(2+)-channels is involved in the PGE(2)/EP(3)R-mediated attenuation of NE exocytosis elicited by H(3)R activation. Conceivably, activation of the Gbetagamma(i) subunit of H(3)R and EP(3)R may also inhibit Ca(2+) entry directly, independent of MAPK intervention. As heart failure, myocardial ischemia and arrhythmic dysfunction are associated with excessive local NE release, attenuation of NE release by H(3)R activation is cardioprotective. Accordingly, this novel H(3)R signaling pathway may ultimately bear therapeutic significance in hyper-adrenergic states.
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Affiliation(s)
- Roberto Levi
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA.
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220
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Humbert-Claude M, Morisset S, Gbahou F, Arrang JM. Histamine H3 and dopamine D2 receptor-mediated [35S]GTPgamma[S] binding in rat striatum: evidence for additive effects but lack of interactions. Biochem Pharmacol 2007; 73:1172-81. [PMID: 17306767 DOI: 10.1016/j.bcp.2007.01.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 12/19/2006] [Accepted: 01/03/2007] [Indexed: 11/28/2022]
Abstract
The interactions in the rat striatum between H(3) receptors (H(3)Rs) and D(2) receptors (D(2)Rs) were investigated with the [(35)S]GTPgamma[S] binding assay. The H(3)R agonist (R)alpha-methylhistamine increased [(35)S]GTPgamma[S] binding to striatal membranes with an EC(50)=14+/-5 nM and a maximal effect of +19+/-1%. This effect was inhibited by the H(3)R antagonist ciproxifan with a K(i)=1.0+/-0.3 nM. The D(2)R agonist quinpirole increased [(35)S]GTPgamma[S] binding to the same membranes with an EC(50)=1.5+/-0.5 microM and a maximal effect of +28+/-2%. Its effect was blocked by haloperidol with a K(i)=0.3+/-0.1 nM. The maximal effects of the H(3)R and D(2)R agonists were additive (+46+/-3%). However, D(2)R ligands did not modify the effects of H(3)R ligands and vice versa. Ciproxifan behaved as an H(3)R inverse agonist and decreased [(35)S]GTPgamma[S] binding. Haloperidol had no effect and did not change the inverse agonist effect of ciproxifan. Administrations for 10 days of ciproxifan (1.5mg/kg/day) or haloperidol (0.5mg/kg/day) did not change the effects of quinpirole and (R)alpha-methylhistamine, respectively. These data suggest that striatal H(3)Rs and D(2)Rs do not interact through their coupling to G-proteins. However, a hyperactivity of histaminergic and dopaminergic neurons being observed in schizophrenia, the additive activations of H(3)Rs and D(2)Rs suggest that they cooperate to generate some schizophrenic symptoms. Such a postsynaptic mechanism may underlie the antipsychotic-like effects of H(3)R inverse agonists and supports their therapeutic interest, alone or as adjunctive treatment with neuroleptics.
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Affiliation(s)
- Marie Humbert-Claude
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 75014 Paris, France
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221
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Harusawa S, Kawamura M, Araki L, Taniguchi R, Yoneyama H, Sakamoto Y, Kaneko N, Nakao Y, Hatano K, Fujita T, Yamamoto R, Kurihara T, Yamatodani A. Synthesis of Novel 4(5)-(5-Aminotetrahydropyran-2-yl)imidazole Derivatives and Their in Vivo Release of Neuronal Histamine Measured by Brain Microdialysis. Chem Pharm Bull (Tokyo) 2007; 55:1245-53. [PMID: 17666853 DOI: 10.1248/cpb.55.1245] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The (2R,5S)-trans- and (2S,5S)-cis-stereoisomers 1a and 1b of 4(5)-(5-aminotetrahydropyran-2-yl)imidazole, which have two chiral centers and adopt a stable chair conformation, were synthesized via cyclization of diol intermediates 7 using L-glutamine as the starting material. Their enantiomers, (2S,5R)-trans-1c and (2R,5R)-cis-1d, were synthesized by the same methodology from D-glutamine. Stereo isomers 1a-d were converted into cyanoguanidines 11a-d, and into N-isopropyl and N-3,3-dimethylbutyl derivatives 12a-d and 13a-d, respectively. The results of in vivo brain microdialysis of the derivatives apparently indicated that only (2S,5R)-isomers increased the release of neuronal histamine. Among the many (2S,5R)-N-alkyl derivatives, 13c (OUP-133) and 18 (OUP-153) increased histamine release to 180-190% and 180-200% of basal levels, respectively, and were found to be novel histamine H(3) antagonists.
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Affiliation(s)
- Shinya Harusawa
- Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka, Japan.
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222
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Abstract
With the availability of an increased number of experimental tools, for example potent and brain-penetrating H1-, H2-, and H3-receptor ligands and mutant mice lacking the histamine synthesis enzyme or the histamine receptors, the functional roles of histaminergic neurons in the brain have been considerably clarified during the recent years, particularly their major role in the control of arousal, cognition, and energy balance. Various approaches tend to establish the implication of histaminergic neurons in schizophrenia. A strong hyperactivity of histamine neurons is induced in rodent brain by administration of methamphetamine or NMDA-receptor antagonists. Histamine neuron activity is modulated by typical and atypical neuroleptics. H3-receptor antagonists/inverse agonists display antipsychotic-like properties in animal models of the disease. Because of the limited predictability value of most animal models and the paucity of drugs affecting histaminergic transmission that were tried so far in human, the evidence remains therefore largely indirect, but supports a role of histamine neurons in schizophrenia.
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Affiliation(s)
- Jean-Michel Arrang
- INSERM, U573, Unité de Neurobiologie et Pharmacologie Moléculaire, Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
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223
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Abstract
The G-protein-coupled receptor (GPCR) family represents the largest and most versatile group of cell surface receptors. Drugs active at these receptors have therapeutic actions across a wide range of human diseases ranging from allergic rhinitis to pain, hypertension and schizophrenia. This review provides a brief historical overview of the properties and signalling characteristics of this important family of receptors.
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Affiliation(s)
- Stephen J Hill
- Institute of Cell Signalling, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham NG7 2UH.
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224
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Abstract
This article reviews the development of our knowledge of the actions of histamine which have taken place during the course of the 20th century. Histamine has been shown to have a key physiological role in the control of gastric acid secretion and a pathophysiological role in a range of allergic disorders. The synthesis of, and pharmacological studies on, selective agonists and antagonists has established the existence of four types of histamine receptor and histamine receptor antagonists have found very important therapeutic applications. Thus, in the 1940s, H(1)-receptor antagonists ('the antihistamines') yielded and still provide valuable treatment for allergic conditions such as hay fever and rhinitis. In the late 1970s and 1980s, H(2)-receptor antagonists (in the discovery of which the two authors were personally involved) revolutionised the treatment of peptic ulcer and other gastric acid-related diseases. The H(3)-receptor antagonists, although available since 1987, have been slower to find a therapeutic role. However, the discovery of nonimidazole derivatives such as brain-penetrating H(3) antagonists has provided drugs that are in early-phase clinical trials, possibly for application in obesity, and a variety of central nervous system disorders, such as memory, learning deficits and epilepsy. Finally, the most recently (1999) discovered H(4) receptor promises the potential to provide drugs acting on the immunological system with possible applications in asthma and inflammation.
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Affiliation(s)
- Mike E Parsons
- Department of Life Sciences, University of Hertfordshire, Hatfield, Hertfordshire AL10 9AB.
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225
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Moreno-Delgado D, Torrent A, Gómez-Ramírez J, de Esch I, Blanco I, Ortiz J. Constitutive activity of H3 autoreceptors modulates histamine synthesis in rat brain through the cAMP/PKA pathway. Neuropharmacology 2006; 51:517-23. [PMID: 16769092 DOI: 10.1016/j.neuropharm.2006.04.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 03/16/2006] [Accepted: 04/18/2006] [Indexed: 11/23/2022]
Abstract
We previously described that agonist-activated histamine H3 autoreceptors inhibit the stimulation of histamine synthesis mediated by calcium/calmodulin- and cAMP-dependent protein kinases (CaMKII and PKA respectively) in histaminergic nerve endings. In the absence of an agonist H3 receptors show partial constitutive activity, so we hypothesized that suppression of constitutive activity by an inverse agonist could stimulate these transduction pathways. We show here that the H3 inverse agonist thioperamide increases histamine synthesis in rat brain cortical slices independently from the amounts of extracellular histamine. Thioperamide effects were mimicked by the inverse agonists clobenpropit and A-331440, but not by the neutral antagonist VUF-5681. In contrast, coincubation with VUF-5681 suppressed thioperamide effects. The effects of thioperamide were completely blocked by the PKA inhibitor peptide myristoyl-PKI14-22, a peptide that did not block depolarization stimulation of histamine synthesis. In addition, thioperamide effects required depolarization and were impaired by blockade of N-type calcium channels (mediating depolarization), but not by CaMKII inhibition. These results indicate that constitutive activity of H3 receptors in rat brain cortex inhibits the adenylate cyclase/PKA pathway, and perhaps also the opening of N-type voltage sensitive calcium channels, but apparently not CaMKII.
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Affiliation(s)
- David Moreno-Delgado
- Universitat Autonoma de Barcelona, Neuroscience Institute and Department of Biochemistry and Molecular Biology, Bellaterra, Spain
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226
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Martel JC, Ormière AM, Leduc N, Assié MB, Cussac D, Newman-Tancredi A. Native rat hippocampal 5-HT1A receptors show constitutive activity. Mol Pharmacol 2006; 71:638-43. [PMID: 17167032 DOI: 10.1124/mol.106.029769] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies have shown that human 5-hydroxytryptamine (5-HT)1A receptors stably expressed in transfected cell lines show constitutive G-protein activity, as revealed by the inhibitory effect of inverse agonists, such as spiperone, on basal guanosine-5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS) binding. In the present study, we evaluated the constitutive activity of native rat 5-HT1A receptors in hippocampal membranes. Using anti-Galphao-antibody capture coupled to scintillation proximity assay under low sodium (30 mM) conditions, we observed high basal [35S]GTPgammaS binding to Galphao subunits (defined as 100%). Under these conditions, 5-HT and the prototypic selective 5-HT1A agonist (+)8-hydroxy-2-(di-n-propylamino)tetralin [(+)-8-OH-DPAT] both stimulated [35S]GTPgammaS binding to Galphao to a similar extent, raising binding to approximately 130% of basal with pEC50 values of 7.91 and 7.87, respectively. The 5-HT1A-selective neutral antagonist [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride (WAY100,635) could block these effects in a competitive manner with pKb values (5-HT, 9.57; (+)-8-OH-DPAT, 9.52) that are consistent with its pKi value at r5-HT1A receptors (9.33). In this native receptor system, spiperone and methiothepin reduced basal [35S]GTPgammaS binding to Galphao in a concentration-dependent manner to 90% of basal with pIC50 values of 7.37 and 7.98, respectively. The inhibition of basal [35S]GTPgammaS binding induced by maximally effective concentrations of spiperone (10 microM) or methiothepin (1 microM) was antagonized by WAY100,635 in a concentration-dependent manner (pKb, 9.52 and 8.87, respectively), thus indicating that this inverse agonism was mediated by 5-HT1A receptors. These data provide the first demonstration that native rat serotonin 5-HT1A receptors can exhibit constitutive activity in vitro.
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Affiliation(s)
- Jean-Claude Martel
- Department of Neurobiology 2, Institut de Recherche Pierre Fabre, France.
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227
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Greasley PJ, Clapham JC. Inverse agonism or neutral antagonism at G-protein coupled receptors: A medicinal chemistry challenge worth pursuing? Eur J Pharmacol 2006; 553:1-9. [PMID: 17081515 DOI: 10.1016/j.ejphar.2006.09.032] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 09/08/2006] [Accepted: 09/11/2006] [Indexed: 11/15/2022]
Abstract
The identification of constitutive, or intrinsic, activity of G-protein coupled receptors has had major impact on receptor theory, the identification of agents that inhibit this ligand-independent receptor activity has led, in turn, to the concept of inverse agonism. It has subsequently emerged that the majority, around 85%, of all known G-protein coupled receptor antagonists are, in fact, inverse agonists. Agents that affect only ligand-dependent receptor activation, i.e. have no effect on constitutive receptor signalling, are termed neutral antagonists and turn out to be relatively rare in pharmacology. Is this relevant for medicinal chemistry? That question is difficult to answer with certainty because there has been little or no effort to understand the structure activity relationships of neutral antagonist vs. inverse agonist molecules. In this review, we suggest that these pharmacological differences may well be translated to differential effects in the whole animal and in medicine. We argue that having either option to inhibit a particular receptor may reveal differences in efficacy and tolerability thus increasing the potential value of a G-protein coupled receptor inhibitor programme. However, since inverse agonists appear to constitute a default inhibitor mode, a systematic survey of the structure activity relationships around what makes a neutral antagonist will be an essential first step towards this goal.
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Affiliation(s)
- Peter J Greasley
- Department of Molecular Pharmacology, AstraZeneca R&D Mölndal, Sweden
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228
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Schlenstedt J, Balfanz S, Baumann A, Blenau W. Am5-HT7: molecular and pharmacological characterization of the first serotonin receptor of the honeybee (Apis mellifera). J Neurochem 2006; 98:1985-98. [PMID: 16945110 DOI: 10.1111/j.1471-4159.2006.04012.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biogenic amine serotonin (5-HT) plays a key role in the regulation and modulation of many physiological and behavioural processes in both vertebrates and invertebrates. These functions are mediated through the binding of serotonin to its receptors, of which 13 subtypes have been characterized in vertebrates. We have isolated a cDNA from the honeybee Apis mellifera (Am5-ht7) sharing high similarity to members of the 5-HT(7) receptor family. Expression of the Am5-HT(7) receptor in HEK293 cells results in an increase in basal cAMP levels, suggesting that Am5-HT(7) is expressed as a constitutively active receptor. Serotonin application to Am5-ht7-transfected cells elevates cyclic adenosine 3',5'-monophosphate (cAMP) levels in a dose-dependent manner (EC(50) = 1.1-1.8 nm). The Am5-HT(7) receptor is also activated by 5-carboxamidotryptamine, whereas methiothepin acts as an inverse agonist. Receptor expression has been investigated by RT-PCR, in situ hybridization, and western blotting experiments. Receptor mRNA is expressed in the perikarya of various brain neuropils, including intrinsic mushroom body neurons, and in peripheral organs. This study marks the first comprehensive characterization of a serotonin receptor in the honeybee and should facilitate further analysis of the role(s) of the receptor in mediating the various central and peripheral effects of 5-HT.
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Affiliation(s)
- Jana Schlenstedt
- Institute of Biochemistry and Biology, University of Potsdam, Golm, Germany
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229
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Affiliation(s)
- Patrizio Blandina
- Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Italy.
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230
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Masdeu C, Faure H, Coulombe J, Schoenfelder A, Mann A, Brabet I, Pin JP, Traiffort E, Ruat M. Identification and characterization of Hedgehog modulator properties after functional coupling of Smoothened to G15. Biochem Biophys Res Commun 2006; 349:471-9. [PMID: 16945339 DOI: 10.1016/j.bbrc.2006.07.216] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Accepted: 07/28/2006] [Indexed: 11/17/2022]
Abstract
The seven-transmembrane receptor Smoothened (Smo) transduces the signal initiated by Hedgehog (Hh) morphogen binding to the receptor Patched (Ptc). We have reinvestigated the pharmacological properties of reference molecules acting on the Hh pathway using various Hh responses and a novel functional assay based on the coexpression of Smo with the alpha subunit of the G15 protein in HEK293 cells. The measurement of inositol phosphate (IP) accumulation shows that Smo has constitutive activity, a response blocked by Ptc which indicates a functional Hh receptor complex. Interestingly, the antagonists cyclopamine, Cur61414, and SANT-1 display inverse agonist properties and the agonist SAG has no effect at the Smo-induced IP response, but converts Ptc-mediated inactive forms of Smo into active ones. An oncogenic Smo mutant does not mediate an increase in IP response, presumably reflecting its inability to reach the cell membrane. These studies identify novel properties of molecules displaying potential interest in the treatment of various cancers and brain diseases, and demonstrate that Smo is capable of signaling through G15.
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Affiliation(s)
- Christelle Masdeu
- CNRS, Institut de Neurobiologie Alfred Fessard-IFR 2118, UPR9040, Laboratoire de Neurobiologie Cellulaire et Moléculaire, Signal Transduction and Developmental Neuropharmacology team, 1 avenue de la Terrasse, Gif-sur-Yvette F-91198, France
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Ligneau X, Perrin D, Landais L, Camelin JC, Calmels TPG, Berrebi-Bertrand I, Lecomte JM, Parmentier R, Anaclet C, Lin JS, Bertaina-Anglade V, la Rochelle CD, d'Aniello F, Rouleau A, Gbahou F, Arrang JM, Ganellin CR, Stark H, Schunack W, Schwartz JC. BF2.649 [1-{3-[3-(4-Chlorophenyl)propoxy]propyl}piperidine, Hydrochloride], a Nonimidazole Inverse Agonist/Antagonist at the Human Histamine H3 Receptor: Preclinical Pharmacology. J Pharmacol Exp Ther 2006; 320:365-75. [PMID: 17005916 DOI: 10.1124/jpet.106.111039] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Histamine H3 receptor inverse agonists are known to enhance the activity of histaminergic neurons in brain and thereby promote vigilance and cognition. 1-{3-[3-(4-Chlorophenyl)propoxy]propyl}piperidine, hydrochloride (BF2.649) is a novel, potent, and selective nonimidazole inverse agonist at the recombinant human H3 receptor. On the stimulation of guanosine 5'-O-(3-[35S]thio)triphosphate binding to this receptor, BF2.649 behaved as a competitive antagonist with a Ki value of 0.16 nM and as an inverse agonist with an EC50 value of 1.5 nM and an intrinsic activity approximately 50% higher than that of ciproxifan. Its in vitro potency was approximately 6 times lower at the rodent receptor. In mice, the oral bioavailability coefficient, i.e., the ratio of plasma areas under the curve after oral and i.v. administrations, respectively, was 84%. BF2.649 dose dependently enhanced tele-methylhistamine levels in mouse brain, an index of histaminergic neuron activity, with an ED50 value of 1.6 mg/kg p.o., a response that persisted after repeated administrations for 17 days. In rats, the drug enhanced dopamine and acetylcholine levels in microdialysates of the prefrontal cortex. In cats, it markedly enhanced wakefulness at the expense of sleep states and also enhanced fast cortical rhythms of the electroencephalogram, known to be associated with improved vigilance. On the two-trial object recognition test in mice, a promnesiant effect was shown regarding either scopolamine-induced or natural forgetting. These preclinical data suggest that BF2.649 is a valuable drug candidate to be developed in wakefulness or memory deficits and other cognitive disorders.
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Affiliation(s)
- X Ligneau
- Bioprojet-Biotech, Saint Grégoire, France
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232
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Nowak P, Dabrowska J, Bortel A, Biedka I, Szczerbak G, Słomian G, Kostrzewa RM, Brus R. Histamine H3 receptor agonist- and antagonist-evoked vacuous chewing movements in 6-OHDA-lesioned rats occurs in an absence of change in microdialysate dopamine levels. Eur J Pharmacol 2006; 552:46-54. [PMID: 17055481 DOI: 10.1016/j.ejphar.2006.08.092] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 07/20/2006] [Accepted: 08/04/2006] [Indexed: 10/24/2022]
Abstract
In rats lesioned neonatally with 6-hydroxydopamine (6-OHDA), repeated treatment with SKF 38393 (1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol), a dopamine D(1)/D(5) receptor agonist, produces robust stereotyped and locomotor activities. The gradual induction of dopamine D(1) receptor supersensitivity is known as a priming phenomenon, and this process is thought to underlie not only the appearance of vacuous chewing movements in humans with tardive dyskinesia, but also the onset of motor dyskinesias in L-dihydroxyphenylalanine (L-DOPA)-treated Parkinson's disease patients. The object of the present study was to determine the possible influence of the histaminergic system on dopamine D(1) agonist-induced activities. We found that neither imetit (5.0 mg/kg i.p.), a histamine H(3) receptor agonist, nor thioperamide (5.0 mg/kg i.p.), a histamine H(3) receptor antagonist/inverse agonist, altered the numbers of vacuous chewing movements in non-primed-lesioned rats. However, in dopamine D(1) agonist-primed rats, thioperamide alone produced a vacuous chewing movements response (i.e., P < 0.05 vs SKF 38393, 1.0 mg/kg i.p.), but did not modify the SKF 38393 effect. Notably, both imetit and thioperamide-induced catalepsy in both non-primed and primed 6-OHDA-lesioned rats, comparable in magnitude to the effect of the dopamine D(1)/D(5) receptor antagonist SCH 23390 (7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine; 0.5 mg/kg i.p.). Furthermore, in primed animals both imetit and thioperamide intensified SCH 23390-evoked catalepsy. In vivo microdialysis established that neither imetit nor thioperamide altered extraneuronal levels of dopamine and its metabolites in the striatum of 6-OHDA-lesioned rats. On the basis of the present study, we believe that histaminergic systems may augment dyskinesias induced by dopamine receptor agonists, independent of direct actions on dopaminergic neurons.
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Affiliation(s)
- Przemysław Nowak
- Department of Pharmacology, Medical University of Silesia, H. Jordana 38, 41-808 Zabrze, Poland.
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233
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Faucard R, Armand V, Héron A, Cochois V, Schwartz JC, Arrang JM. N-methyl-d-aspartate receptor antagonists enhance histamine neuron activity in rodent brain. J Neurochem 2006; 98:1487-96. [PMID: 16923161 DOI: 10.1111/j.1471-4159.2006.04002.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The modulation of histamine neuron activity by various non-competitive NMDA-receptor antagonists was evaluated by changes in tele-methylhistamine (t-MeHA) levels and histidine decarboxylase (hdc) mRNA expression induced in rodent brain. The NMDA open-channel blockers phencyclidine (PCP) and MK-801 enhanced t-MeHA levels in mouse brain by 50-60%. Ifenprodil, which interacts with polyamine sites of NR2B-containing NMDA receptors, had no effect. PCP also increased hdc mRNA expression in the rat tuberomammillary nucleus. The enhancement of t-MeHA levels elicited by MK-801 (ED50 of approximately 0.1 mg/kg) was observed in the hypothalamus, cerebral cortex, striatum and hippocampus. Control t-MeHA levels and the t-MeHA response to MK-801 were not different in male and female mice. Double immunostaining for HDC and NMDA receptor subunits showed that histamine neurons of the rat tuberomammillary nucleus express NMDA receptor subunit 1 (NR1) with NMDA receptor subunit 2A (NR2A) and NMDA receptor 2B subunit (NR2B). In addition, immunoreactivity for the neuronal glutamate transporter EAAC1 was observed near most histaminergic perikarya. Hence, these findings support the existence of histamine/glutamate functional interactions in the brain. The increase in histamine neuron activity induced by NMDA receptor antagonists further suggests a role of histamine neurons in psychotic disorders. In addition, the decrease in MK-801-induced hyperlocomotion observed in mice after administration of ciproxifan further strengthens the potential interest of H3-receptor antagonist/inverse agonists for the symptomatic treatment of schizophrenia.
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234
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Celanire S, Wijtmans M, Talaga P, Leurs R, de Esch IJP. Keynote review: histamine H3 receptor antagonists reach out for the clinic. Drug Discov Today 2006; 10:1613-27. [PMID: 16376822 DOI: 10.1016/s1359-6446(05)03625-1] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Antagonists of the histamine H(1) and H(2) receptors have been successful as blockbuster drugs for treating allergic conditions and gastric ulcers, respectively. As such, histamine receptors have made a significant contribution to establishing G-Protein-coupled receptors as the favored drug targets of the industry. In this light, it can easily be understood that the discovery of a third histamine receptor subtype (H(3)R) in 1983 was greeted with considerable excitement. However, characterization of the H(3)R turned out to be far from trivial. In the past five years, molecular biology approaches have given fresh impetus to the H(3)R research field. As a result, H(3)R ligands are where they were anticipated to be 20 years ago: at the center of attention and on the verge of an anticipated breakthrough as the next generation of histaminergic blockbuster drugs. Here, we assess the status of the H(3)R medicinal chemistry programs of the various players in the field, as far as can be deduced from patent applications and scientific literature.
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Affiliation(s)
- Sylvain Celanire
- Department of Chemical Research, Chemin du Foriest, B-1420 Braine-l'Alleud, Belgium
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235
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Gbahou F, Vincent L, Humbert-Claude M, Tardivel-Lacombe J, Chabret C, Arrang JM. Compared pharmacology of human histamine H3 and H4 receptors: structure-activity relationships of histamine derivatives. Br J Pharmacol 2006; 147:744-54. [PMID: 16432504 PMCID: PMC1751501 DOI: 10.1038/sj.bjp.0706666] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Various histamine derivatives were investigated at the human H3 receptor (H3R) and H4 receptor (H4R) stably expressed in human embryonic kidney (HEK)-293 cells using [125I]iodoproxyfan and [3H]histamine binding, respectively. In Tris buffer, [3H]histamine binding to membranes of HEK(hH4R) cells was monophasic (K(D) of 3.8+/-0.8 nM). In phosphate buffer, the Hill coefficient was decreased (n(H) = 0.5+/-0.1) and a large fraction of the binding was converted into a low-affinity component (K(D) = 67+/-27 nM). The inhibition of [3H]histamine binding by two agonists, a protean agonist and five antagonists/inverse agonists confirms that the potency of many H3R ligands is retained or only slightly reduced at the H4R. Histamine derivatives substituted with methyl groups in alpha, beta or N(alpha) position of the side chain retained a nanomolar potency at the H3R, but their affinity was dramatically decreased at the H4R. With relative potencies to histamine of 282 and 0.13% at the H3R and H4R, respectively, (+/-)-alpha,beta-dimethylhistamine is a potent and selective H3R agonist. Chiral alpha-branched analogues exhibited a marked stereoselectivity at the H3R and H4R, the enantiomers with a configuration equivalent to L-histidine being preferred at both receptors. The methylsubstitution of the imidazole ring was also studied. The relative potency to histamine of 4-methylhistamine (4-MeHA) at the H4R (67%) was similar to that reported at H2 receptors but, owing to its high affinity at the H4R (Ki = 7.0+/-1.2 nM) and very low potency at H1- and H3-receptors, it can be considered as a potent and selective H4R agonist. On inhibition of forskolin-induced cAMP formation, all the compounds tested, including 4-MeHA, behaved as full agonists at both receptors. However, the maximal inhibition achieved at the H4R (approximately -30%) was much lower than at the H3R (approximately -80%). Thioperamide behaved as an inverse agonist at both receptors and increased cAMP formation with the same maximal effect (approximately +25%). In conclusion, although the pharmacological profiles of the human H3R and H4R overlap, the structure-activity relationships of histamine derivatives at both receptors strongly differ and lead to the identification of selective compounds.
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Affiliation(s)
- Florence Gbahou
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
| | - Ludwig Vincent
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
| | - Marie Humbert-Claude
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
| | - Joel Tardivel-Lacombe
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
| | - Claude Chabret
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
| | - Jean-Michel Arrang
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
- Author for correspondence:
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236
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Witte DG, Yao BB, Miller TR, Carr TL, Cassar S, Sharma R, Faghih R, Surber BW, Esbenshade TA, Hancock AA, Krueger KM. Detection of multiple H3 receptor affinity states utilizing [3H]A-349821, a novel, selective, non-imidazole histamine H3 receptor inverse agonist radioligand. Br J Pharmacol 2006; 148:657-70. [PMID: 16715122 PMCID: PMC1751875 DOI: 10.1038/sj.bjp.0706752] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. A-349821 is a selective histamine H3 receptor antagonist/inverse agonist. Herein, binding of the novel non-imidazole H3 receptor radioligand [3H]A-349821 to membranes expressing native or recombinant H3 receptors from rat or human sources was characterized and compared with the binding of the agonist [3H]N--methylhistamine ([3H]NMH). 2. [3H]A-349821 bound with high affinity and specificity to an apparent single class of saturable sites and recognized human H3 receptors with 10-fold higher affinity compared to rat H3 receptors. [3H]A-349821 detected larger populations of receptors compared to [3H]NMH. 3. Displacement of [3H]A-349821 binding by H3 receptor antagonists/inverse agonists was monophasic, suggesting recognition of a single binding site, while that of H3 receptor agonists was biphasic, suggesting recognition of both high- and low-affinity H3 receptor sites. 4. pKi values of high-affinity binding sites for H3 receptor competitors utilizing [3H]A-349821 were highly correlated with pKi values obtained with [3H]NalphaMH, consistent with labelling of H3 receptors by [3H]A-349821. 5. Unlike assays utilizing [3H]NMH, addition of GDP had no effect on saturation parameters measured with [3H]A-349821, while displacement of [3H]A-349821 binding by the H3 receptor agonist histamine was sensitive to GDP. 6. In conclusion, [3H]A-349821 labels interconvertible high- and low-affinity states of the H3 receptor, and displays improved selectivity over imidazole-containing H3 receptor antagonist radioligands. [3H]A-349821 competition studies showed significant differences in the proportions and potencies of high- and low-affinity sites across species, providing new information about the fundamental pharmacological nature of H3 receptors.
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Affiliation(s)
- David G Witte
- Neuroscience Research, Dept. R4MN, Global Pharmaceutical Research Division, Abbott Laboratories, Bldg. AP9A-2, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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237
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Dai H, Zhang Z, Zhu Y, Shen Y, Hu W, Huang Y, Luo J, Timmerman H, Leurs R, Chen Z. Histamine protects against NMDA-induced necrosis in cultured cortical neurons through H receptor/cyclic AMP/protein kinase A and H receptor/GABA release pathways. J Neurochem 2006; 96:1390-400. [PMID: 16478529 DOI: 10.1111/j.1471-4159.2005.03633.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using histamine and the H3 receptor antagonist thioperamide, the roles of histamine receptors in NMDA-induced necrosis were investigated in rat cultured cortical neurons. Within 3 h of intense NMDA insult, most neurons died by necrosis. Histamine reversed the neurotoxicity in a concentration-dependent manner and showed peak protection at a concentration of 10(-7) m. This protection was antagonized by the H2 receptor antagonists cimetidine and zolantidine but not by the H1 receptor antagonists pyrilamine and diphenhydramine. In addition, the selective H2 receptor agonist amthamine mimicked the protection by histamine. This action was prevented by cimetidine but not by pyrilamine. 8-Bromo-cAMP also mimicked the effect of histamine. In contrast, both the adenylyl cyclase inhibitor 9-(tetrahydro-2-furanyl)-9H-purine-6-amine and the cAMP-dependent protein kinase inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinolinesulfonamide reversed the protection by histamine. Thioperamide also attenuated NMDA-induced excitotoxicity, which was reversed by the H3 receptor agonist (R)-alpha-methylhistamine but not by pyrilamine and cimetidine. In addition, the protection by thioperamide was inhibited by the GABA(A) receptor antagonists picrotoxin and bicuculline. Further study demonstrated that the protection by thioperamide was due to increased GABA release in NMDA-stimulated samples. These results indicate that not only the H2 receptor/cAMP/cAMP-dependent protein kinase pathway but also the H3 receptor/GABA release pathway can attenuate NMDA-induced neurotoxicity.
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Affiliation(s)
- Haibin Dai
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou, China 310031
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238
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 388] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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239
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Tokita S, Takahashi K, Kotani H. Recent advances in molecular pharmacology of the histamine systems: physiology and pharmacology of histamine H3 receptor: roles in feeding regulation and therapeutic potential for metabolic disorders. J Pharmacol Sci 2006; 101:12-8. [PMID: 16648667 DOI: 10.1254/jphs.fmj06001x4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Histamine H3 receptors (H3Rs) are autoreceptors that negatively regulate the release of histamine and other neurotransmitters such as norepinephrine, dopamine, and acetylcholine in the central nervous system (CNS). Consistent with the wide-spread projection of histaminergic neurons from the lateral hypothalamus, H3Rs are widely distributed in the CNS and are believed to play a variety of physiological roles, including regulation of feeding, arousal, cognition, pain, and endocrine systems. To further understand the physiological roles of H3Rs in vivo, we produced H3R knockout (H3R-/-) mice and found that H3R-/- mice displayed hyperphagia and late-onset obesity associated with hyperinsulinemia and leptinemia, the fundamental marks of metabolic syndromes. A series of non-imidazole H3R antagonists/inverse agonists with improved selectivity and potency have been developed and were found to regulate feeding and body weight gain in laboratory animals. Taken together, these observations suggest that H3Rs are involved in the regulation of feeding behavior and body weight. Several H3R inverse agonists targeting cognitive disorders and dementia have entered clinical trials. These trials will give critical information about the physiological functions of H3Rs in humans.
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Affiliation(s)
- Shigeru Tokita
- Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., Ibaraki, Japan
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240
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Leterrier C, Lainé J, Darmon M, Boudin H, Rossier J, Lenkei Z. Constitutive activation drives compartment-selective endocytosis and axonal targeting of type 1 cannabinoid receptors. J Neurosci 2006; 26:3141-53. [PMID: 16554465 PMCID: PMC6674101 DOI: 10.1523/jneurosci.5437-05.2006] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The type 1 cannabinoid receptor (CB1R) is one of the most abundant G-protein-coupled receptors (GPCRs) in the brain, predominantly localized to axons of GABAergic neurons. Like several other neuronal GPCRs, CB1R displays significant in vitro constitutive activity (i.e., spontaneous activation in the absence of ligand). However, a clear biological role for constitutive GPCR activity is still lacking. This question was addressed by studying the consequences of constitutive activation on the intracellular trafficking of endogenous or transfected CB1Rs in cultured hippocampal neurons using optical and electron microscopy. We found that constitutive activity results in a permanent cycle of endocytosis and recycling, which is restricted to the somatodendritic compartment. Thus, CB1Rs are continuously removed by endocytosis from the plasma membrane in the somatodendritic compartment but not in axons, where CB1Rs accumulate on surface. Blocking constitutive activity by short-term incubation with inverse agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide (AM281) results in sequestration of recycled CB1Rs on the somatodendritic plasma membrane. Long-term inhibition of endocytosis by cotransfection of dominant-negative proteins results in impaired axonal polarization of surface-bound CB1Rs. Kinetic analysis shows that the majority of newly synthesized CB1Rs arrive first to the somatodendritic plasma membrane, from where they are rapidly removed by AM281-sensitive constitutive endocytosis before being delivered to axons. Thus, constitutive-activity driven somatodendritic endocytosis is required for the proper axonal targeting of CB1R, representing a novel, conformation-dependent targeting mechanism for axonal GPCRs.
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241
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Pantel J, Legendre M, Cabrol S, Hilal L, Hajaji Y, Morisset S, Nivot S, Vie-Luton MP, Grouselle D, de Kerdanet M, Kadiri A, Epelbaum J, Le Bouc Y, Amselem S. Loss of constitutive activity of the growth hormone secretagogue receptor in familial short stature. J Clin Invest 2006; 116:760-8. [PMID: 16511605 PMCID: PMC1386106 DOI: 10.1172/jci25303] [Citation(s) in RCA: 240] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 12/06/2005] [Indexed: 11/17/2022] Open
Abstract
The growth hormone (GH) secretagogue receptor (GHSR) was cloned as the target of a family of synthetic molecules endowed with GH release properties. As shown recently through in vitro means, this receptor displays a constitutive activity whose clinical relevance is unknown. Although pharmacological studies have demonstrated that its endogenous ligand--ghrelin--stimulates, through the GHSR, GH secretion and appetite, the physiological importance of the GHSR-dependent pathways remains an open question that gives rise to much controversy. We report the identification of a GHSR missense mutation that segregates with short stature within 2 unrelated families. This mutation, which results in decreased cell-surface expression of the receptor, selectively impairs the constitutive activity of the GHSR, while preserving its ability to respond to ghrelin. This first description, to our knowledge, of a functionally significant GHSR mutation, which unveils the critical importance of the GHSR-associated constitutive activity, discloses an unusual pathogenic mechanism of growth failure in humans.
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Affiliation(s)
- Jacques Pantel
- INSERM, U654, Centre Hospitalier Universitaire Henri-Mondor, Créteil, France.
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242
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Hancock AA, Fox GB. Perspectives on cognitive domains, H3 receptor ligands and neurological disease. Expert Opin Investig Drugs 2006; 13:1237-48. [PMID: 15461554 DOI: 10.1517/13543784.13.10.1237] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Histamine H(3) receptor agonists and antagonists have been evaluated in numerous in vitro and in vivo animal models to better understand how H(3) receptors modulate neurotransmitter function in the central nervous system. Likewise, behavioural models have explored the hypothesis that changes in neurotransmitter release could enhance cognitive function in human diseases. This review examines the reported effects of H(3) receptor ligands and how they influence cognitive behaviour. These data are interpreted on the basis of different cognitive domains that are relevant to neuropsychiatric diseases. Because of the diversity of H(3) receptors, their function and their influence on neurotransmitter systems, considerable promise exists for H(3) ligands to treat diseases in which aspects of learning and memory are impaired. However, because of the complexities of the histaminergic system and H(3) receptors and the lack of clinical data so far, proof of principle for use in human disease remains to be established.
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Affiliation(s)
- Arthur A Hancock
- Abbott Laboratories, Department R4MN, Building AP9A/3, Neuroscience Division, 100 Abbott Park Road, Abbott Park, IL 60064-6125, USA.
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243
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Adan RAH. Constitutive Receptor Activity series Endogenous inverse agonists and constitutive receptor activity in the melanocortin system. Trends Pharmacol Sci 2006; 27:183-6. [PMID: 16500715 DOI: 10.1016/j.tips.2006.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 01/04/2006] [Accepted: 02/09/2006] [Indexed: 11/25/2022]
Abstract
The recent discovery of melanocortin receptor mutations that selectively decrease constitutive receptor activity in obese individuals supports the physiological relevance of constitutive melanocortin receptor activity and its control by an endogenous inverse agonist. Furthermore, studies using mice that lack endogenous melanocortin receptor agonists show that differences in coat color are caused by different degrees of constitutive melanocortin receptor signaling regulated by an endogenous inverse agonist. Thus, the regulation of constitutive activity of melanocortin receptors is important for the normal control of pigmentation and body-weight homeostasis.
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Affiliation(s)
- Roger A H Adan
- Rudolf Magnus Institute of Neuroscience, Department of Pharmacology and Anatomy, University Medical Center Utrecht, PO Box 85060, 3508 AB, Utrecht, The Netherlands.
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244
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Hancock AA. The challenge of drug discovery of a GPCR target: Analysis of preclinical pharmacology of histamine H3 antagonists/inverse agonists. Biochem Pharmacol 2006; 71:1103-13. [PMID: 16513092 DOI: 10.1016/j.bcp.2005.10.033] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 10/19/2005] [Accepted: 10/20/2005] [Indexed: 10/25/2022]
Abstract
Although the histamine H(3) receptor was identified pharmacologically in 1983, and despite widespread pharmaceutical interest in the target, no compound interacting specifically with this site has undergone successful clinical examination to develop the necessary proof-of-concept data. Therefore, clinical knowledge of the therapeutic potential of H(3) receptor antagonists in neuropsychiatric diseases, in metabolic diseases or in sleep disorders has yet to determine if the preclinical data that show broad efficacy in animal models of the aforementioned states are relevant to current unmet medical needs. H(3) receptors are complex, with species-related sequence differences that impact pharmacological responses. The receptors have a complex gene organization that provides opportunity for multiple slice isoforms, most of which remain poorly characterized even within a species. H(3) receptors are constitutively active, although the extent of this could vary either between species and/or receptor splice isoforms, both of which may provide opportunity for preferential coupling to different G-proteins. Thus, it is not surprising that the pharmacological effects of known H(3) ligands are complex and diverse, since these agents may act both as agonists and antagonists in different systems. Moreover, other compounds show inverse agonism in some models but neutral antagonist activity in others. Some of this diversity may be related to different ligand-dependent receptor activation states or to the effects of key amino acids important for ligand recognition. This commentary provides an overview of these complexities as applied to the H(3) receptor and the challenges these intricacies create for drug discovery.
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Affiliation(s)
- A A Hancock
- Abbott Laboratories, Global Pharmaceutical Research and Development, Department R4MN, Abbott Park, IL 60064-6125, USA.
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Govoni M, Lim HD, El-Atmioui D, Menge WMPB, Timmerman H, Bakker RA, Leurs R, De Esch IJP. A Chemical Switch for the Modulation of the Functional Activity of Higher Homologues of Histamine on the Human Histamine H3 Receptor: Effect of Various Substitutions at the Primary Amino Function. J Med Chem 2006; 49:2549-57. [PMID: 16610798 DOI: 10.1021/jm0504353] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In an effort to establish the structural requirements for agonism, neutral antagonism, and inverse agonism at the human histamine H(3) receptor (H(3)R) we have prepared a series of higher homologues of histamine in which the terminal nitrogen of the side chain has been either mono- or disubstituted with several aliphatic, alicyclic, and aromatic moieties or incorporated in cyclic systems. The novel ligands have been pharmacologically investigated in vitro for their affinities on the human H(3)R and H(4)R subtypes by radioligand displacement experiments and for their intrinsic H(3)R activities via a CRE-mediated beta-galactosidase reporter gene assay. Subtle changes of the substitution pattern at the side chain nitrogen alter enormously the pharmacological activity of the ligands, resulting in a series of compounds with a wide spectrum of pharmacological activities. Among the several neutral H(3)R antagonists identified within this series, compounds 2b and 2h display an H(3)R affinity in the low nanomolar concentration range (pK(i) values of 8.1 and 8.4, respectively). A very potent and selective H(3)R agonist (1l, pEC(50) = 8.9, alpha = 0.94) and a very potent, though not highly selective, H(3)R inverse agonist (2k, pIC(50) = 8.9, alpha = -0.97) have been identified as well.
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Affiliation(s)
- Marinella Govoni
- Leiden/Amsterdam Center for Drug Research, Department of Pharmacochemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Huang ZL, Mochizuki T, Qu WM, Hong ZY, Watanabe T, Urade Y, Hayaishi O. Altered sleep-wake characteristics and lack of arousal response to H3 receptor antagonist in histamine H1 receptor knockout mice. Proc Natl Acad Sci U S A 2006; 103:4687-92. [PMID: 16537376 PMCID: PMC1450232 DOI: 10.1073/pnas.0600451103] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Histaminergic neurons play an important role in the regulation of sleep-wake behavior through histamine H(1) receptors (H(1)R). Blockade of the histamine H(3) receptor (H(3)R) is proposed to induce wakefulness by regulating the release of various wake-related transmitters, not only histamine. In the present study, we characterized sleep-wake cycles of H(1)R knockout (KO) mice and their arousal responses to an H(3)R antagonist. Under baseline conditions, H(1)R KO mice showed sleep-wake cycles essentially identical to those of WT mice but with fewer incidents of brief awakening (<16-sec epoch), prolonged durations of non-rapid eye movement (NREM) sleep episodes, a decreased number of state transitions between NREM sleep and wakefulness, and a shorter latency for initiating NREM sleep after an i.p. injection of saline. The H(1)R antagonist pyrilamine mimicked these effects in WT mice. When an H(3)R antagonist, ciproxifan, was administered i.p., wakefulness increased in WT mice in a dose-dependent manner but did not increase at all in H(1)R KO mice. In vivo microdialysis revealed that the i.p. application of ciproxifan increased histamine release from the frontal cortex in both genotypes of mice. These results indicate that H(1)R is involved in the regulation of behavioral state transitions from NREM sleep to wakefulness and that the arousal effect of the H(3)R antagonist completely depends on the activation of histaminergic systems through H(1)R.
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Affiliation(s)
- Zhi-Li Huang
- *Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
- National Key Laboratory of Medical Neurobiology, Shanghai Medical College of Fudan University, Shanghai 200032, People's Republic of China
| | - Takatoshi Mochizuki
- *Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02115; and
| | - Wei-Min Qu
- *Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
| | - Zong-Yuan Hong
- *Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
| | - Takeshi Watanabe
- Unit for Immune Surveillance Research, Research Center for Allergy and Immunology, RIKEN Institute, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Yoshihiro Urade
- *Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
| | - Osamu Hayaishi
- *Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
- To whom correspondence should be addressed at:
Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan.
E-mail:
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247
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Bond RA, Ijzerman AP. Recent developments in constitutive receptor activity and inverse agonism, and their potential for GPCR drug discovery. Trends Pharmacol Sci 2006; 27:92-6. [PMID: 16406086 DOI: 10.1016/j.tips.2005.12.007] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 11/21/2005] [Accepted: 12/15/2005] [Indexed: 11/18/2022]
Abstract
The concept of constitutively active G-protein-coupled receptors is now firmly rooted in receptor pharmacology. Many independent research groups have contributed to its acceptance since its introduction by Costa and Herz in 1989. This concept necessitated a revised ligand classification, and a new category of inverse agonists was introduced alongside existing agonist and antagonist ligands. Initially, it was hoped that new therapeutic modalities would become available. However, the drug industry has not adopted inverse agonism as a design criterion and instead accepted that some compounds emerge as (neutral) antagonists in compound screening, whereas other compounds possess inverse agonistic activity. In this article, we summarize aspects of the impact of constitutive activity on the drug-discovery process: for example, its use in orphan receptor assays, its link with pharmacogenetics and genomics, and its relevance for currently marketed drugs.
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Affiliation(s)
- Richard A Bond
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun, Houston, TX 77204-5037, USA
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Letavic MA, Barbier AJ, Dvorak CA, Carruthers NI. Recent medicinal chemistry of the histamine H3 receptor. PROGRESS IN MEDICINAL CHEMISTRY 2006; 44:181-206. [PMID: 16697898 DOI: 10.1016/s0079-6468(05)44405-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Affiliation(s)
- Michael A Letavic
- Johnson and Johnson Pharmaceutical Research and Development LLC, San Diego, CA 92121, USA
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Ito S, Yoshimoto R, Miyamoto Y, Mitobe Y, Nakamura T, Ishihara A, MacNeil DJ, Kanatani A, Tokita S. Detailed pharmacological characterization of GT-2331 for the rat histamine H3 receptor. Eur J Pharmacol 2006; 529:40-6. [PMID: 16316645 DOI: 10.1016/j.ejphar.2005.10.066] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 10/21/2005] [Accepted: 10/26/2005] [Indexed: 11/23/2022]
Abstract
Histamine H(3) receptor antagonists are potential therapeutic agents for cognitive dysfunction, epilepsy, hypersomnia and obesity. GT-2331 (4-[(R,R)-2-(5,5-dimethyl-1-hexynyl)cyclopropyl]-1H-imidazole) was originally identified as a potent histamine H(3) receptor antagonist. However, recent reports demonstrated a complex pharmacology for GT-2331. To further understand the pharmacological profile of GT-2331, we characterized GT-2331 using various in vitro and in vivo assays. In vitro, GT-2331 behaved as a full agonist on adenylyl cyclase inhibition and as a partial agonist on [(35)S]GTPgammaS binding at the recombinant rat histamine H(3) receptor. In contrast, in vivo, GT-2331 had no effect on brain histamine turnover while the histamine H(3) receptor agonist R-alpha-methylhistamine significantly decreased histamine turnover. Furthermore, GT-2331 completely blocked R-alpha-methylhistamine-induced water intake, suggesting that GT-2331 behaves as a full antagonist. Thus, GT-2331 displayed the spectrum of pharmacological activities from full agonism to full antagonism, these observations suggest that histamine H(3) receptor ligands need to be carefully evaluated in various paradigms.
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Affiliation(s)
- Sayaka Ito
- Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan
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250
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Morgan PJ, Ross AW, Mercer JG, Barrett P. What can we learn from seasonal animals about the regulation of energy balance? PROGRESS IN BRAIN RESEARCH 2006; 153:325-37. [PMID: 16876584 DOI: 10.1016/s0079-6123(06)53019-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Weight loss in humans requires, except during an illness, some form of imposed restriction on food intake or increase in energy expenditure. This necessitates overcoming powerful peripheral and central signals that serve to protect against negative energy balance. The identification of the systems and pathways involved has come from mouse models with genetic and targeted mutations, e.g., ob/ob and MC4 R(-/-) as well as rat models of obesity. Study of seasonal animals has shown that they undergo annual cycles of body fattening and adipose tissue loss as important adaptations to environmental change, yet these changes appear to involve mechanisms distinct from those known already. One animal model, the Siberian hamster, exhibits marked, but reversible, weight loss in response to shortening day length. The body weight is driven by a decrease in food intake with the magnitude of the loss of body weight being directly related to the length of time of exposure to short photoperiod. The most important facet of this response is that the point of energy balance is continuously re-adjusted during the transition in body weight reflecting an apparent 'sliding set point'. Studies have focused on identifying the neural basis of this mechanism. Initial studies of known genes (e.g., NPY, POMC, and AgRP) both through the measurement of gene expression in the arcuate nucleus as well as following intracerebroventricular (i.c.v.) injection indicated that the systems involved are not those involved in restoring energy balance following energy deficits. Instead, a novel mechanism of regulation is implied. Recent studies have begun to explore the neural basis of the seasonal body weight response. A discrete and novel region of the posterior arcuate nucleus, the dorsal medial posterior arcuate nucleus (dmpARC) has been identified, where a battery of gene expression changes for signalling molecules (vgf and histamine H3 receptor) and transcription factors (RXRgamma and RAR) occur in association with seasonal changes in body weight. This work provides the basis of a potentially novel mechanism of energy balance regulation.
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Affiliation(s)
- Peter J Morgan
- Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen, AB21 9SB, UK.
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