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Bender AM, Parr LC, Livingston WB, Lindsley CW, Merryman WD. 2B Determined: The Future of the Serotonin Receptor 2B in Drug Discovery. J Med Chem 2023; 66:11027-11039. [PMID: 37584406 PMCID: PMC11073569 DOI: 10.1021/acs.jmedchem.3c01178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2023]
Abstract
The cardiotoxicity associated with des-ethyl-dexfenfluramine (norDF) and related agonists of the serotonin receptor 2B (5-HT2B) has solidified the receptor's place as an "antitarget" in drug discovery. Conversely, a growing body of evidence has highlighted the utility of 5-HT2B antagonists for the treatment of pulmonary arterial hypertension (PAH), valvular heart disease (VHD), and related cardiopathies. In this Perspective, we summarize the link between the clinical failure of fenfluramine-phentermine (fen-phen) and the subsequent research on the role of 5-HT2B in disease progression, as well as the development of drug-like and receptor subtype-selective 5-HT2B antagonists. Such agents represent a promising class for the treatment of PAH and VHD, but their utility has been historically understudied due to the clinical disasters associated with 5-HT2B. Herein, it is our aim to examine the current state of 5-HT2B drug discovery, with an emphasis on the receptor's role in the central nervous system (CNS) versus the periphery.
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Affiliation(s)
- Aaron M Bender
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Lauren C Parr
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - William B Livingston
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Craig W Lindsley
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - W David Merryman
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37240, United States
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De Deurwaerdère P, Chagraoui A, Di Giovanni G. Serotonin/dopamine interaction: Electrophysiological and neurochemical evidence. PROGRESS IN BRAIN RESEARCH 2021; 261:161-264. [PMID: 33785130 DOI: 10.1016/bs.pbr.2021.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interaction between serotonin (5-HT) and dopamine (DA) in the central nervous system (CNS) plays an important role in the adaptive properties of living animals to their environment. These are two modulatory, divergent systems shaping and regulating in a widespread manner the activity of neurobiological networks and their interaction. The concept of one interaction linking these two systems is rather elusive when looking at the mechanisms triggered by these two systems across the CNS. The great variety of their interacting mechanisms is in part due to the diversity of their neuronal origin, the density of their fibers in a given CNS region, the distinct expression of their numerous receptors in the CNS, the heterogeneity of their intracellular signaling pathway that depend on the cellular type expressing their receptors, and the state of activity of neurobiological networks, conditioning the outcome of their mutual influences. Thus, originally conceptualized as inhibition of 5-HT on DA neuron activity and DA neurotransmission, this interaction is nowadays considered as a multifaceted, mutual influence of these two systems in the regulation of CNS functions. These new ways of understanding this interaction are of utmost importance to envision the consequences of their dysfunctions underlined in several CNS diseases. It is also essential to conceive the mechanism of action of psychotropic drugs directly acting on their function including antipsychotic, antidepressant, antiparkinsonian, and drug of abuse together with the development of therapeutic strategies of Alzheimer's diseases, epilepsy, obsessional compulsive disorders. The 5-HT/DA interaction has a long history from the serendipitous discovery of antidepressants and antipsychotics to the future, rationalized treatments of CNS disorders.
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Affiliation(s)
- Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique, Institut des Neurosciences Intégratives et Cognitives d'Aquitaine, UMR 5287, Bordeaux, France.
| | - Abdeslam Chagraoui
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine of Normandy (IRIB), Normandie University, UNIROUEN, INSERM U1239, Rouen, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, United Kingdom.
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Lo CH, Huber EC, Sachs JN. Conformational states of TNFR1 as a molecular switch for receptor function. Protein Sci 2020; 29:1401-1415. [PMID: 31960514 DOI: 10.1002/pro.3829] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 12/14/2022]
Abstract
Tumor necrosis factor receptor 1 (TNFR1) is a transmembrane receptor that plays a key role in the regulation of the inflammatory pathway. While inhibition of TNFR1 has been the focus of many studies for the treatment of autoimmune diseases such as rheumatoid arthritis, activation of the receptor is important for the treatment of immunodeficiency diseases such as HIV and neurodegenerative diseases such as Alzheimer's disease where a boost in immune signaling is required. In addition, activation of other TNF receptors such as death receptor 5 or FAS receptor is important for cancer therapy. Here, we used a previously established TNFR1 fluorescence resonance energy transfer (FRET) biosensor together with a fluorescence lifetime technology as a high-throughput screening platform to identify a novel small molecule that activates TNFR1 by increasing inter-monomeric spacing in a ligand-independent manner. This shows that the conformational rearrangement of pre-ligand assembled receptor dimers can determine the activity of the receptor. By probing the interaction between the receptor and its downstream signaling molecule (TRADD) our findings support a new model of TNFR1 activation in which varying conformational states of the receptor act as a molecular switch in determining receptor function.
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Affiliation(s)
- Chih Hung Lo
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Evan C Huber
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Jonathan N Sachs
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
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Cartolano MC, Gancel HN, Lonthair J, Wood CM, McDonald MD. Pulsatile urea excretion in Gulf toadfish: the role of circulating serotonin and additional 5-HT receptor subtypes. J Comp Physiol B 2019; 189:537-548. [DOI: 10.1007/s00360-019-01223-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 04/28/2019] [Accepted: 06/24/2019] [Indexed: 11/28/2022]
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De Deurwaerdère P, Di Giovanni G. Serotonergic modulation of the activity of mesencephalic dopaminergic systems: Therapeutic implications. Prog Neurobiol 2016; 151:175-236. [PMID: 27013075 DOI: 10.1016/j.pneurobio.2016.03.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/13/2016] [Accepted: 03/14/2016] [Indexed: 12/14/2022]
Abstract
Since their discovery in the mammalian brain, it has been apparent that serotonin (5-HT) and dopamine (DA) interactions play a key role in normal and abnormal behavior. Therefore, disclosure of this interaction could reveal important insights into the pathogenesis of various neuropsychiatric diseases including schizophrenia, depression and drug addiction or neurological conditions such as Parkinson's disease and Tourette's syndrome. Unfortunately, this interaction remains difficult to study for many reasons, including the rich and widespread innervations of 5-HT and DA in the brain, the plethora of 5-HT receptors and the release of co-transmitters by 5-HT and DA neurons. The purpose of this review is to present electrophysiological and biochemical data showing that endogenous 5-HT and pharmacological 5-HT ligands modify the mesencephalic DA systems' activity. 5-HT receptors may control DA neuron activity in a state-dependent and region-dependent manner. 5-HT controls the activity of DA neurons in a phasic and excitatory manner, except for the control exerted by 5-HT2C receptors which appears to also be tonically and/or constitutively inhibitory. The functional interaction between the two monoamines will also be discussed in view of the mechanism of action of antidepressants, antipsychotics, anti-Parkinsonians and drugs of abuse.
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Affiliation(s)
- Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5293, 33076 Bordeaux Cedex, France.
| | - Giuseppe Di Giovanni
- Department of Physiology & Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, UK.
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Serum and ascitic fluid serotonin levels and 5-hydroxyindoleacetic acid urine excretion in the liver of cirrhotic patients with encephalopathy. Adv Med Sci 2014; 58:251-6. [PMID: 24384770 DOI: 10.2478/ams-2013-0010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE The excess and deficit of serotonin can be the cause of somatic and mental disorders. The aim of this study was to evaluate serotonin levels in blood and ascitic fluid as well as excretion of 5-hydroxyindoleacetic acid (5-HIAA) in urine in patients with hepatic encephalopathy (HE). MATERIAL AND METHODS The study included 75 alcoholic cirrhotic patients divided into 3 groups (HE1, HE2, HE3), 25 patients each, with grade 1, 2 and 3 of hepatic encephalopathy according to West-Haven classification. The control group (C) included 25 clinically healthy volunteers. Venous blood and ascitic fluid were collected in fasting. On the same day a 24-hour urine collection was performed. Immunoenzymatic method was used to determine the serotonin level in serum and ascitic fluid, and 5-HIAA in urine (IBL-RE-59121, RE-59131). RESULTS In the control group, mean serum serotonin level (ng/ml) was 155.5 ± 38.1 and in the 3 study groups: HE1 - 175.2 ± 32.4 (NS), HE2 - 137.2 ± 28.6 (NS), HE3 - 108.3 ± 46.3 (p<0.001). Serotonin concentration in ascitic fluid was on the average about 25% of its level in serum. The excretion of 5-HIAA in urine (mg/24h) in all groups, was: C - 5.9 ± 2.1, HE1 - 5.8 ± 1.8 (NS), HE2 - 4.8 ± 1.2(NS), HE3 - 4.3 ± 1.3 (p<0.05). CONCLUSION The results of our study indicate that serum and ascitic fluid level of serotonin and urine excretion of 5-HIAA depends on the grade of hepatic encephalopathy. In patients with severe hepatic encephalopathy serotonin concentration in blood is decreased which can affect some clinical manifestation of this disease.
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Ljungvall I, Höglund K, Lilliehöök I, Oyama MA, Tidholm A, Tvedten H, Häggström J. Serum serotonin concentration is associated with severity of myxomatous mitral valve disease in dogs. J Vet Intern Med 2013; 27:1105-12. [PMID: 23865457 DOI: 10.1111/jvim.12137] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 04/26/2013] [Accepted: 05/28/2013] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) has recently been suggested to play a role in the development of naturally acquired myxomatous mitral valve disease (MMVD) in dogs. AIM To investigate the association between serum 5-HT concentration and MMVD severity in dogs, and to assess potential associations between serum 5-HT concentrations and dog characteristics, echocardiographic variables, heart rate, systolic blood pressure, presence of macrothrombocytosis, and plateletcrit. ANIMALS A total of 120 client-owned dogs. MATERIAL AND METHODS Dogs were prospectively recruited and were classified by standard echocardiography into healthy (dogs of breeds predisposed to MMVD, but without echocardiographic evidence of the disease), mild, moderate, or severe MMVD groups. Serum 5-HT concentrations were analyzed using an ELISA. RESULTS Dogs with severe MMVD had lower serum 5-HT concentrations than healthy dogs (P = .0025) and dogs with mild MMVD (P = .0011). Unilinear and multiple regression analyses showed that serum 5-HT concentrations decreased with increasing left atrial to aortic root ratio (LA/Ao), were higher in Cavalier King Charles Spaniel (CKCS) dogs compared to dogs of other breeds, and were higher in female dogs than in male dogs. The LA/Ao was the variable most strongly associated with serum 5-HT concentration. CONCLUSIONS AND CLINICAL IMPORTANCE The finding of higher serum 5-HT concentrations in dogs of breeds predisposed to the early onset of MMVD (CKCS) and dogs with mild MMVD suggests that alterations in 5-HT signaling might play a role in progression of early stages of MMVD.
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Affiliation(s)
- I Ljungvall
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Frere AW, McDonald MD. The effect of stress on gill basolateral membrane binding kinetics of 5-ht2 receptor ligands: potential implications for urea excretion mechanisms. ACTA ACUST UNITED AC 2013; 319:237-48. [PMID: 23495168 DOI: 10.1002/jez.1788] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 11/13/2012] [Accepted: 02/06/2013] [Indexed: 11/07/2022]
Abstract
The goal of this study was to determine the relationship between cortisol and the toadfish serotonin 2A (5-HT2A ) receptor, which is believed to be responsible for the activation of the toadfish urea transporter, tUT. We hypothesize that elevations in cortisol would play a role in the regulation of the 5-HT2A receptor at the level of mRNA expression, ligand binding, and/or function. To test this idea, cortisol levels were manipulated by either crowding or through treatment with the cortisol synthesis blocker, metyrapone. Crowded fish had significantly higher circulating cortisol levels compared to uncrowded fish and cortisol levels in metyrapone-treated fish were significantly lower than saline-treated controls. No significant difference was measured in gill 5-HT2A mRNA expression levels between uncrowded and crowded, control- or metyrapone-treated fish. Furthermore, no significant difference was measured in [(3) H]-5-HT binding kinetics or in the competitive binding of the 5-HT2 agonist, α-methyl 5-HT, to isolated gill basolateral membranes of uncrowded or crowded toadfish. However, the binding maximum (Bmax ) of the 5-HT2A receptor antagonist, [(3) H]-ketanserin, was significantly different between all four groups of fish (metyrapone > control > crowded > uncrowded). Furthermore, metyrapone-treated fish excreted approximately twofold more urea compared to controls when injected with α-methyl 5-HT, a 5-HT2 receptor agonist shown to stimulate urea excretion. Our results suggest that cortisol may have differential effects on 5-HT receptor binding, which could have potential implications on the control of pulsatile urea excretion in toadfish.
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Affiliation(s)
- Alexander W Frere
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA
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Astrocytic transactivation by α2A-adrenergic and 5-HT2B serotonergic signaling. Neurochem Int 2010; 57:421-31. [DOI: 10.1016/j.neuint.2010.04.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 03/24/2010] [Accepted: 04/28/2010] [Indexed: 12/11/2022]
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Li B, Zhang S, Li M, Hertz L, Peng L. Serotonin increases ERK1/2 phosphorylation in astrocytes by stimulation of 5-HT2B and 5-HT2C receptors. Neurochem Int 2010; 57:432-9. [PMID: 20450948 DOI: 10.1016/j.neuint.2010.04.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 03/24/2010] [Accepted: 04/26/2010] [Indexed: 11/29/2022]
Abstract
We have previously shown that fluoxetine causes ERK(1/2) phosphorylation in cultured mouse astrocytes mediated exclusively by stimulation of 5-HT(2B) receptors (Li et al., 2008b). This raises the question whether this is also the case for serotonin (5-HT) itself. In the present study serotonin was found to induce ERK(1/2) phosphorylation by stimulation of 5-HT(2B) receptors with high affinity (EC(50): 20-30 pM), and by stimulation of 5-HT(2C) receptor with low affinity (EC(50): 1 microM or higher). ERK(1/2) phosphorylation induced by stimulation of either 5-HT(2B) or 5-HT(2C) receptors was mediated by epidermal growth factor (EGF) receptor transactivation (Peng et al., this issue), shown by the inhibitory effect of AG1478, an inhibitor of the EGF receptor tyrosine kinase, and GM6001, an inhibitor of Zn-dependent metalloproteinases, and thus of 5-HT(2B) receptor-mediated EGF receptor agonist release. It is discussed that the high potency of the 5-HT(2B)-mediated effect is consistent with literature data for binding affinity of serotonin to cloned human 5-HT(2B) receptors and with observations of low extracellular concentrations of serotonin in brain, which would allow a demonstrated moderate and modality-dependent increase in specific brain areas to activate 5-HT(2B) receptors. In contrast the relevance of the observed 5-HT(2C) receptors on astrocytes is questioned.
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Affiliation(s)
- Baoman Li
- Department of Clinical Pharmacology, China Medical University, Heping District, Shenyang, PR China
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Arndt JW, Reynolds CA, Singletary GE, Connolly JM, Levy RJ, Oyama MA. Serum serotonin concentrations in dogs with degenerative mitral valve disease. J Vet Intern Med 2009; 23:1208-13. [PMID: 19709352 DOI: 10.1111/j.1939-1676.2009.0378.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Increased serotonin (5HT) signaling has been implicated in valvular disease of humans and animals, including canine degenerative mitral valve disease (DMVD). High circulating 5HT concentration is a potential source of increased signaling, and serum 5HT concentrations have not been previously reported in dogs with DMVD. HYPOTHESIS Dogs with DMVD and small breed dogs predisposed to DMVD have higher serum 5HT concentrations than large breed controls. ANIMALS Fifty dogs affected with DMVD, 34 dogs predisposed to DMVD but without cardiac murmur or echocardiographic evidence of DMVD, and 36 healthy large breed control dogs. METHODS Prospective analysis. Serum 5HT concentration was measured by an ELISA test. RESULTS Median serum 5HT concentration was significantly higher in dogs with DMVD and in dogs predisposed to DMVD as compared with controls (DMVD, 765.5 ng/mL [interquartile range, 561.3-944.4]; predisposed, 774.9 ng/mL [528.3-1,026]; control, 509.8 ng/mL [320.8-708.8]; P= .0001). Subgroup analysis of predisposed dogs indicated significantly higher serum 5HT concentrations in Cavalier King Charles Spaniel (CKCS) dogs than in other breeds (CKCS, 855.0 ng/mL [635.8-1,088]; non-CKCS, 554.2 ng/mL [380.6-648.4]; P= .0023). Age, platelet count, and platelet morphology were not correlated with 5HT concentration in any group. CONCLUSIONS AND CLINICAL IMPORTANCE Dogs with DMVD had significantly higher serum 5HT concentrations when compared with large breed control dogs. Healthy CKCS dogs had significantly higher serum 5HT concentrations than other healthy dogs predisposed to DMVD. Additional investigation into a possible role of 5HT in the pathogenesis of DMVD is warranted.
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Affiliation(s)
- J W Arndt
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Shen L, Ji HF. Molecular basis for cis-urocanic acid as a 5-HT(2A) receptor agonist. Bioorg Med Chem Lett 2009; 19:5307-9. [PMID: 19683920 DOI: 10.1016/j.bmcl.2009.07.143] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 07/13/2009] [Accepted: 07/30/2009] [Indexed: 11/16/2022]
Abstract
The underlying mechanisms of urocanic acid (UA) to induce immune suppression remain elusive until the recent finding that cis-UA acts via the serotonin, 5-hydroxytryptamine (5-HT) receptor subtype 5-HT(2A). In the present study, the interactions of cis-UA to 5-HT(2A) receptor were explored and compared with those of 5-HT to the same receptor using computational docking. Similar binding modes were observed for cis-UA and 5-HT with 5-HT(2A) receptor and the former possessed relatively higher binding affinity, which may account for cis-UA being a serotonin receptor agonist. Moreover, the molecular basis for the distinct binding affinities between the trans- and cis-UA with 5-HT(2A) receptor was also provided.
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Affiliation(s)
- Liang Shen
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study, Shandong University of Technology, Zibo 255049, PR China
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Herth MM, Piel M, Debus F, Schmitt U, Lüddens H, Rösch F. Preliminary in vivo and ex vivo evaluation of the 5-HT2A imaging probe [(18)F]MH.MZ. Nucl Med Biol 2009; 36:447-54. [PMID: 19423013 DOI: 10.1016/j.nucmedbio.2009.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 01/16/2009] [Accepted: 01/25/2009] [Indexed: 11/30/2022]
Abstract
INTRODUCTION The 5-HT(2A) receptor is one of the most interesting targets within the serotonergic system because it is involved in a number of important physiological processes and diseases. METHODS [(18)F]MH.MZ, a 5-HT(2A) antagonistic receptor ligand, is labeled by (18)F-fluoroalkylation of the corresponding desmethyl analogue MDL 105725 with 2-[(18)F]fluoroethyltosylate ([(18)F]FETos). In vitro binding experiments were performed to test selectivity toward a broad spectrum of neuroreceptors by radioligand binding assays. Moreover, first micro-positron emission tomography (microPET) experiments, ex vivo organ biodistribution, blood cell and protein binding and brain metabolism studies of [(18)F]MH.MZ were carried out in rats. RESULTS [(18)F]MH.MZ showed a K(i) of 3 nM toward the 5-HT(2A) receptor and no appreciable affinity for a variety of receptors and transporters. Ex vivo biodistribution as well as microPET showed highest brain uptake at approximately 5 min p.i. and steady state after approximately 30 min p.i. While [(18)F]MH.MZ undergoes extensive first-pass metabolism which significantly reduces its bioavailability, it is insignificantly metabolized within the brain. The binding potential in the rat frontal cortex is 1.45, whereas the cortex to cerebellum ratio was determined to be 2.7 after approximately 30 min. CONCLUSION Results from microPET measurements of [(18)F]MH.MZ are in no way inferior to data known for [(11)C]MDL 100907 at least in rats. [(18)F]MH.MZ appears to be a highly potent and selective serotonergic PET ligand in small animals.
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Affiliation(s)
- Matthias M Herth
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, D-55128 Mainz, Germany.
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Fluoxetine-mediated 5-HT2B receptor stimulation in astrocytes causes EGF receptor transactivation and ERK phosphorylation. Psychopharmacology (Berl) 2008; 201:443-58. [PMID: 18758753 DOI: 10.1007/s00213-008-1306-5] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Accepted: 08/12/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE Fluoxetine has relatively high affinity for Gq/11 protein-coupled 5-HT(2) receptors. Part of these receptors in brain are on astrocytes, where fluoxetine causes an increase in free cytosolic calcium concentration ([Ca(2+)](i)) and phosphorylation of extracellular regulated kinase 1 and 2 (ERK(1/2)). OBJECTIVE The objectives of the study are to identify subtype of the 5-HT(2) receptor involved, to establish whether ERK(1/2) phosphorylation is a result of 5-HT(2)-mediated transactivation of epidermal growth factor (EGF) receptors (EGFRs), and to determine signaling pathways up- and downstream of ERK(1/2). MATERIALS AND METHODS Primary cultures of mouse astrocytes, which express all three subtypes of the 5-HT(2) receptor but no 5-HT(2) transporter, were used. ERK(1/2) phosphorylation and c-Fos and FosB protein expression were determined with Western blotting, and c-fos and fosB mRNA expression with reverse transcription polymerase chain reaction. Receptor subtype was investigated with subtype-specific 5-HT antagonists and 5-HT(2B) receptor depletion and signaling pathways by EGFR phosphorylation, using immunoprecipitation and Western blotting, inhibition of protein kinase C (PKC), and [Ca(2+)](i) chelation by BAPTA/AM. RESULTS ERK(1/2) phosphorylation was abolished by SB204741, a universal 5-HT(2) receptor antagonist, and in 5-HT(2B) receptor-depleted cells, but unaffected by 5-HT(2A) or 5-HT(2C) receptor antagonists (M100907 and SB242084). Phosphorylation of ERK(1/2) and EGFRs was abolished by AG 1478, an inhibitor of EGFR tyrosine kinases, and GM 6001, an inhibitor of Zn-dependent metalloproteinases, suggesting growth factor "shedding" and transactivation of EGFRs. Chelation of [Ca(2+)](i) or PKC inhibition with GF 109203X abrogated ERK(1/2) phosphorylation. Up-regulated mRNA and protein expression of c-fos and fosB was abolished by SB204741, AG1478, and by U0126, an inhibitor of ERK phosphorylation by MAP kinase/ERK kinase.
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Blaazer A, Smid P, Kruse C. Structure-Activity Relationships of Phenylalkylamines as Agonist Ligands for 5-HT2AReceptors. ChemMedChem 2008; 3:1299-309. [DOI: 10.1002/cmdc.200800133] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Serotonin pharmacology in the gastrointestinal tract: a review. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:181-203. [PMID: 18398601 DOI: 10.1007/s00210-008-0276-9] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Accepted: 02/15/2008] [Indexed: 12/17/2022]
Abstract
Serotonin (5-hydroxytryptamine or 5-HT) plays a critical physiological role in the regulation of gastrointestinal (GI) function. 5-HT dysfunction may also be involved in the pathophysiology of a number of functional GI disorders, such as chronic constipation, irritable bowel syndrome and functional dyspepsia. This article describes the role of 5-HT in the enteric nervous system (ENS) of the mammalian GI tract and the receptors with which it interacts. Existing serotonergic therapies that have proven effective in the treatment of GI functional disorders and the potential of drugs currently in development are also highlighted. Advances in our understanding of the physiological and pathophysiological roles of 5-HT in the ENS and the identification of selective receptor ligands bodes well for the future development of more efficacious therapies for patients with functional GI disorders.
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2-Alkyl-4-aryl-pyrimidine fused heterocycles as selective 5-HT2A antagonists. Bioorg Med Chem Lett 2008; 18:2103-8. [PMID: 18282705 DOI: 10.1016/j.bmcl.2008.01.090] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 01/17/2008] [Accepted: 01/23/2008] [Indexed: 10/22/2022]
Abstract
The synthesis and SAR for a novel series of 2-alkyl-4-aryl-tetrahydro-pyrido-pyrimidines and 2-alkyl-4-aryl-tetrahydro-pyrimido-azepines is described. Representative compounds were shown to be subtype selective 5-HT(2A) antagonists. Optimal placement of a basic nitrogen relative to the pyrimidine and the presence of a 4-fluorophenyl group in the pyrimidine 4-position was found to have a profound effect on affinity and selectivity.
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Recent Advances on the 5-HT5A, 5-HT6 and 5-HT7 Receptors. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2008. [DOI: 10.1016/s0065-7743(08)00002-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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Walterscheid JP, Nghiem DX, Kazimi N, Nutt LK, McConkey DJ, Norval M, Ullrich SE. Cis-urocanic acid, a sunlight-induced immunosuppressive factor, activates immune suppression via the 5-HT2A receptor. Proc Natl Acad Sci U S A 2006; 103:17420-5. [PMID: 17085585 PMCID: PMC1859944 DOI: 10.1073/pnas.0603119103] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exposure to UV radiation induces skin cancer and suppresses the immune response. To induce immune suppression, the electromagnetic energy of UV radiation must be absorbed by an epidermal photoreceptor and converted into a biologically recognizable signal. Two photoreceptors have been recognized: DNA and trans-urocanic acid (UCA). Trans-UCA is normally found in the outermost layer of skin and isomerizes to the cis isomer upon exposure to UV radiation. Although UCA was identified as a UV photoreceptor years ago, and many have documented its ability to induce immune suppression, its exact mode of action remains elusive. Particularly vexing has been the identity of the molecular pathway by which cis-UCA mediates immune suppression. Here we provide evidence that cis-UCA binds to the serotonin [5-hydroxytryptamine (5-HT)] receptor with relatively high affinity (Kd = 4.6 nM). Anti-cis-UCA antibody precipitates radiolabeled 5-HT, and the binding is inhibited by excess 5-HT and/or excess cis-UCA. Similarly, anti-5-HT antibody precipitates radiolabeled cis-UCA, and the binding is inhibited by excess 5-HT or excess cis-UCA. Calcium mobilization was activated when a mouse fibroblast line, stably transfected with the human 5-HT2A receptor, was treated with cis-UCA. Cis-UCA-induced calcium mobilization was blocked with a selective 5-HT2A receptor antagonist. UV- and cis-UCA-induced immune suppression was blocked by antiserotonin antibodies or by treating the mice with 5-HT2A receptor antagonists. Our findings identify cis-UCA as a serotonin receptor ligand and indicate that the immunosuppressive effects of cis-UCA and UV radiation are mediated by activation of the 5-HT2A receptor.
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Affiliation(s)
- Jeffrey P. Walterscheid
- *Department of Immunology and Center for Cancer Immunology Research and
- Graduate School of Biomedical Sciences, University of Texas, Houston, TX 77030; and
| | - Dat X. Nghiem
- *Department of Immunology and Center for Cancer Immunology Research and
- Graduate School of Biomedical Sciences, University of Texas, Houston, TX 77030; and
| | - Nasser Kazimi
- *Department of Immunology and Center for Cancer Immunology Research and
| | - Leta K. Nutt
- Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030
- Graduate School of Biomedical Sciences, University of Texas, Houston, TX 77030; and
| | - David J. McConkey
- Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030
- Graduate School of Biomedical Sciences, University of Texas, Houston, TX 77030; and
| | - Mary Norval
- Medical Microbiology, University of Edinburgh Medical School, Edinburgh EH8 9AG, Scotland
| | - Stephen E. Ullrich
- *Department of Immunology and Center for Cancer Immunology Research and
- Graduate School of Biomedical Sciences, University of Texas, Houston, TX 77030; and
- To whom correspondence should be addressed at:
Department of Immunology/Unit 902, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030. E-mail:
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Oyama MA, Chittur SV. Genomic expression patterns of mitral valve tissues from dogs with degenerative mitral valve disease. Am J Vet Res 2006; 67:1307-18. [PMID: 16881841 DOI: 10.2460/ajvr.67.8.1307] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate global genome expression patterns of mitral valve tissues from dogs with degenerative mitral valve disease (DMVD). SAMPLE POPULATION Anterior mitral valve leaflets of 4 dogs with severe DMVD and 4 healthy control dogs. PROCEDURES Transcriptional activities of 23,851 canine DNA sequences were determined by use of an oligonucleotide microarray. Genome expression patterns of tissue from dogs with DMVD were evaluated by measuring the relative amount of complementary RNA hybridization to the microarray probes and by comparing it with gene expression from healthy control dogs. RESULTS 229 transcripts were differentially expressed (>or= 2-fold change). In dogs with DMVD, expression of 159 transcripts was upregulated and expression of 70 transcripts was downregulated. Of the 229 transcripts, 152 genes could be specifically identified. These genes were grouped into 1 of 9 categories on the basis of their primary physiologic function. Grouping revealed that pathways involving cell signaling, inflammation, extracellular matrix, immune function, cell defense, and metabolism were generally upregulated. Inflammatory cytokines and the serotonin-transforming growth factor-beta pathway were identified as contributory to the pathophysiologic aspects of DMVD. CONCLUSIONS AND CLINICAL RELEVANCE Evaluation of global expression patterns provides a molecular portrait of mitral valve disease, yields insight into the pathophysiologic aspects of DMVD, and identifies intriguing genes and pathways for further study.
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Affiliation(s)
- Mark A Oyama
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, 61802, USA
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Sutton SW, Bonaventure P, Kuei C, Nepomuceno D, Wu J, Zhu J, Lovenberg TW, Liu C. G-protein-coupled receptor (GPCR)-142 does not contribute to relaxin-3 binding in the mouse brain: further support that relaxin-3 is the physiological ligand for GPCR135. Neuroendocrinology 2005; 82:139-50. [PMID: 16679775 DOI: 10.1159/000091267] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Accepted: 12/13/2005] [Indexed: 11/19/2022]
Abstract
Relaxin-3 is a recently discovered member of the insulin/relaxin superfamily that has been shown to be the endogenous ligand for G-protein-coupled receptor (GPCR)135 (SALPR). In addition, relaxin-3 has demonstrated affinity and functional agonism for GPCR142 (GPR100) and LGR7 receptors in vitro. Recent evidence suggests GPCR142 is the insulin-like peptide 5 (INSL5) receptor and LGR7 is the actual relaxin receptor. We have recently described a chimeric R3/I5 peptide that selectively activates GPCR135 and GPCR142, but lacks affinity for LGR7. GPCR142 is a pseudogene in the rat, which allowed the use of [(125)I]-R3/I5 to show GPCR135-like binding sites in the rat central nervous system by autoradiography. However, mouse GPCR142 is a viable gene. In the present study we explore whether GPCR142 is expressed in the mouse brain and whether it is likely to contribute to or interfere with the pharmacological evaluation of relaxin-3 ligands. Competition binding studies confirmed mINSL5 and [(125)I]-mINSL5 bind to mGPCR142 with high affinity. However, no detectable specific [(125)I]-mINSL5 binding sites were detected throughout the mouse brain and unlabelled INSL5 did not displace [(125)I]-R3/I5 binding sites, indicating an absence of detectable GPCR142 binding sites. Consistent with these findings, neither GPCR142 nor INSL5 mRNA were detectable in mouse brain by in situ hybridization. Overall, the distribution of GPCR135 mRNA overlapped with the distribution of GPCR135 binding sites shown by autoradiography using [(125)I]-R3/I5. GPCR135 mRNA and GPCR135 receptor binding sites are most prominent in the mouse amygdala and hypothalamus. These data suggest that relaxin-3/GPCR135 is the receptor ligand pair with physiological relevance in mouse brain.
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Affiliation(s)
- Steven W Sutton
- Johnson & Johnson Pharmaceutical Research & Development, LLC, San Diego, CA 92121, USA.
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