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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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Poulie CBM, Liu N, Jensen AA, Bunch L. Design, Synthesis, and Pharmacological Characterization of Heterobivalent Ligands for the Putative 5-HT 2A/mGlu 2 Receptor Complex. J Med Chem 2020; 63:9928-9949. [PMID: 32815361 DOI: 10.1021/acs.jmedchem.0c01058] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report the synthesis of the first series of heterobivalent ligands targeting the putative heteromeric 5-HT2A/mGlu2 receptor complex, based on the 5-HT2A antagonist MDL-100,907 and the mGlu2 ago-PAM JNJ-42491293. The functional properties of monovalent and heterobivalent ligands were characterized in 5-HT2A-, mGlu2/Gqo5-, 5-HT2A/mGlu2-, and 5-HT2A/mGlu2/Gqo5-expressing HEK293 cells using a Ca2+ imaging assay and a [3H]ketanserin binding assay. Pronounced functional crosstalk was observed between the two receptors in 5-HT2A/mGlu2 and 5-HT2A/mGlu2/Gqo5 cells. While the synthesized monovalent ligands retained the 5-HT2A antagonist and mGlu2 ago-PAM functionalities, the seven bivalent ligands inhibited 5-HT-induced responses in 5-HT2A/mGlu2 cells and both 5-HT- and Glu-induced responses in 5-HT2A/mGlu2/Gqo5 cells. However, no definitive correlation between the functional potency and spacer length of the ligands was observed, an observation substantiated by the binding affinities exhibited by the compounds in 5-HT2A, 5-HT2A/mGlu2, and 5-HT2A/mGlu2/Gqo5 cells. In conclusion, while functional crosstalk between 5-HT2A and mGlu2 was demonstrated, it remains unclear how these heterobivalent ligands interact with the putative receptor complex.
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Affiliation(s)
- Christian B M Poulie
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen OE, Denmark
| | - Na Liu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen OE, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen OE, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen OE, Denmark
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Effects of the synthetic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) on ethanol consumption and place conditioning in male mice. Psychopharmacology (Berl) 2019; 236:3567-3578. [PMID: 31309240 PMCID: PMC6895420 DOI: 10.1007/s00213-019-05328-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 07/08/2019] [Indexed: 12/27/2022]
Abstract
RATIONALE Approximately 20 million adults in the USA have an alcohol use disorder (AUD). There are clinical and preclinical data suggesting that psychedelics may have benefits for AUD. OBJECTIVE To investigate the effects of the synthetic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) on the behavioral effects of ethanol. METHODS The effects of DOI were examined using ethanol-induced place conditioning (1.8 g/kg ethanol) and 2-bottle choice ethanol drinking (20% v/v), using a dose of DOI (3 mg/kg) that produced the maximal response in the serotonin 2A (5-HT2A) receptor-dependent head-twitch assay. Interactions between DOI and ethanol (3 g/kg) were examined using the ethanol-induced loss of righting reflex procedure and blood-ethanol analysis. To examine additional mechanisms by which psychedelics may interact with ethanol, we determined whether DOI reverses ethanol-induced nitric oxide release in macrophages, a marker of inflammation. RESULTS DOI significantly attenuated ethanol-induced place conditioning and ethanol drinking. DOI-induced suppression of alcohol drinking depended upon 5-HT2A receptors, was selective for alcohol over water, and was selective for high alcohol-preferring subjects. DOI had no apparent pharmacokinetic interactions with ethanol, and DOI reduced ethanol-induced nitric oxide release. CONCLUSIONS Our findings demonstrate that DOI blocks ethanol place conditioning and selectively reduces voluntary ethanol consumption. This may be related to modulation of the effects of ethanol in the reward circuitry of the brain, ethanol-induced neuroinflammation, or a combination of both. Additional studies to elucidate the mechanisms through which psychedelics attenuate the effects of ethanol would inform the pathophysiology of AUD and potentially provide new treatment options.
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Ray A, Canal CE, Ehlen JC, Rice KC, Murnane KS. M100907 and BD 1047 attenuate the acute toxic effects of methamphetamine. Neurotoxicology 2019; 74:91-99. [PMID: 31163210 PMCID: PMC6750996 DOI: 10.1016/j.neuro.2019.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 01/04/2023]
Abstract
There are no Food and Drug Administration approved pharmacotherapies for methamphetamine (METH) overdose, thus identifying novel drug targets to prevent this devastating adverse event is a public-health imperative. Previous research suggests that serotonin and sigma receptors may contribute to the adverse effects of METH. The present study assessed whether pretreatment with the 5-HT2A receptor antagonist M100907 or the sigma 1 (σ1) receptor antagonist BD 1047 attenuated METH-induced lethality, hyperthermia, convulsions, and seizures. Male, Swiss-Webster mice received intraperitoneal injections of M100907 (1 and 10 mg/kg), BD 1047 (10 mg/kg), or a combination of M100907 (1 mg/kg) and BD 1047 (10 mg/kg) prior to treatment with METH (78 mg/kg). Convulsions and lethality were assessed by observation, core body temperature was assessed by surgically implanted telemetric probes, and seizures were assessed by electroencephalography. M100907 reduced METH-elicited lethality from 67% to 33%, BD1047 reduced METH-elicited lethality from 67% to 50%, and combined administration of both agents eliminated lethality in all mice tested. Similarly, both agents and their combination reduced METH-elicited seizures and convulsions. None of the treatments decreased METH-induced hyperthermia. This research suggests that reducing METH-induced seizures is an important factor in reducing lethality associated with METH overdose. However, future studies should examine whether M100907 and BD 1047 modulate METH-induced hypertension and other adverse effects that may also contribute to METH overdose. Our data support the continued investigation of compounds that target 5-HT2A and σ1 receptors in METH-induced overdose, including their potential to yield emergency reversal agents.
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Affiliation(s)
- Azizi Ray
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, Mercer University Health Sciences Center, Atlanta, GA, USA
| | - Clinton E Canal
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, Mercer University Health Sciences Center, Atlanta, GA, USA
| | | | - Kenner C Rice
- Drug Design and Synthesis Section, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, USA
| | - Kevin Sean Murnane
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, Mercer University Health Sciences Center, Atlanta, GA, USA.
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Soto CA, Shashack MJ, Fox RG, Bubar MJ, Rice KC, Watson CS, Cunningham KA, Gilbertson SR, Anastasio NC. Novel Bivalent 5-HT 2A Receptor Antagonists Exhibit High Affinity and Potency in Vitro and Efficacy in Vivo. ACS Chem Neurosci 2018; 9:514-521. [PMID: 29111677 DOI: 10.1021/acschemneuro.7b00309] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The 5-HT2A receptor (5-HT2AR) plays an important role in various neuropsychiatric disorders, including substance use disorder and schizophrenia. Homodimerization of this receptor has been suggested, but tools that allow direct assessment of the relevance of the 5-HT2AR:5-HT2AR homodimer in these disorders are necessary. We chemically modified the selective 5-HT2AR antagonist M100907 to synthesize a series of homobivalent ligands connected by ethylene glycol linkers of varying lengths that may be useful tools for probing 5-HT2AR:5-HT2AR homodimer function. We tested these molecules for 5-HT2AR antagonist activity in a cell line stably expressing the functional 5-HT2AR and quantified a downstream signaling target, activation (phosphorylation) of extracellular regulated kinases 1/2 (ERK1/2), in comparison to in vivo efficacy of altering spontaneous or cocaine-evoked locomotor activity in rats. All of the synthetic compounds inhibited 5-HT-mediated phosphorylation of ERK1/2 in the cellular signaling assay; the potency of the bivalent ligands varied as a function of linker length, with the intermediate linker lengths being the most potent. The Ki values for the binding of bivalent ligands to 5-HT2AR were only slightly lower than the values for the parent (+)-M100907 compound, but significant selectivity for 5-HT2AR over 5-HT2BR or 5-HT2CR binding was retained. In addition, the 11-atom-linked bivalent 5-HT2AR antagonist (2 mg/kg, intraperitoneally) demonstrated efficacy on par with that of (+)-M100907 in inhibiting cocaine-evoked hyperactivity. As we develop further strategies for ligand-evoked receptor assembly and analyses of diverse signaling and functional roles, these novel homobivalent 5-HT2AR antagonist ligands will serve as useful in vitro and in vivo probes of 5-HT2AR structure and function.
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Affiliation(s)
| | | | | | | | - Kenner C. Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland 20892, United States
| | | | | | - Scott R. Gilbertson
- Department of Chemistry, University of Houston, Houston, Texas 77004, United States
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Gilbertson SR, Chen YC, Soto CA, Yang Y, Rice KC, Cunningham KA, Anastasio NC. Synthesis and activity of functionalizable derivatives of the serotonin (5-HT) 5-HT 2A receptor (5-HT 2AR) antagonist M100907. Bioorg Med Chem Lett 2018; 28:1381-1385. [PMID: 29555153 DOI: 10.1016/j.bmcl.2018.02.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 02/28/2018] [Indexed: 01/19/2023]
Abstract
The approach of tethering together two known receptor ligands, to be used as molecular probes for the study of G protein-coupled receptor (GPCR) systems, has proven to be a valuable approach. Selective ligands that possess functionality that can be used to link to other ligands, are useful in the development of novel antagonists and agonists. Such molecules can also be attached to reporter molecules, such as fluorophores, for the study of GPCR dimerization and its role in signaling. The highly selective serotonin (5-HT) 5-HT2A receptor (5-HT2AR) antagonist M100907 (volinanserin) is of clinical interest in the treatment of neurological and mental health disorders. Here, we synthesized the most active (+)-M100907 enantiomer as well as a series of derivatives that possessed either an alkyne or an azide. The triazole resulting from the dipolar cycloaddition of these groups did not interfere with the ability of the bivalent ligand to act as an antagonist. Thus, we have synthesized a number of compounds which will prove useful in elucidating the role of the 5-HT2AR in the central nervous system.
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Affiliation(s)
- Scott R Gilbertson
- Department of Chemistry, University of Houston, Houston, TX, United States; Center for Addiction Research, United States.
| | - Ying-Chu Chen
- Department of Chemistry, University of Houston, Houston, TX, United States
| | | | - Yaxing Yang
- Department of Chemistry, University of Houston, Houston, TX, United States
| | - Kenner C Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, MD, United States
| | - Kathryn A Cunningham
- Center for Addiction Research, United States; Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Noelle C Anastasio
- Center for Addiction Research, United States; Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
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Javid FA, Afshin-Javid S, Horn CC. Further investigation of the effects of 5-hydroxytryptamine, 8-OH-DPAT and DOI to mediate contraction and relaxation responses in the intestine and emesis in Suncus murinus. Eur J Pharmacol 2018; 821:79-87. [PMID: 29277716 DOI: 10.1016/j.ejphar.2017.12.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/20/2017] [Accepted: 12/21/2017] [Indexed: 11/29/2022]
Abstract
5-HT receptors are implicated in many gastrointestinal disorders. However, the precise role of 5-HT in mediating GI responses in Suncus murnius is still unclear. Therefore in this study, the effects of 5-HT and its agonists were investigated in Suncus. The involvement of 5-HT2C receptors in mediating emesis was also investigated. The ability of 5-HT and its agonists/antagonists at 5-HT1A and 5-HT2 to modify GI motility was investigated in vitro and in vivo. WAY100635 (a 5-HT1A antagonist) inhibited the contraction response to 5-HT in the proximal segments without affecting the maximum response; whilst enhancing the contraction to 5-HT (>30.0nM) in the distal intestine. The selective 5-HT2A and 5-HT2B receptor antagonists MDL-100907 and RS-127445 attenuated 5-HT-induced contractions (<10.0µM) in the distal segments. RS-127445 also attenuated 5-HT-induced contractions in the central segments. The selective 5-HT2C receptor antagonist SB-242084, attenuated the responses to 5-HT (> 3.0nM) in the proximal and central but not the distal regions. 8-OH-DPAT-induced relaxation was resistant to the antagonism by 5-HT1A/7 antagonists. DOI in the presence of 5-HT1A/2A/2B/2C antagonists induced greater contraction responses (>1.0µM) in most tissues, whilst RS-127445, or SB-242084, reduced the responses to DOI (< 1.0µM) in some tissues. SB-242084 also suppressed emesis-induced by motion and intragastric CuSO4. In conclusion, within different regions of intestine, 5-HT2 receptors are differently involved in contraction and emetic responses and that 8-OH-DPAT induces relaxation via non-5-HT1A/7 receptors. Suncus could provide a model to investigate these diverse actions of 5-HT.
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Affiliation(s)
- Farideh A Javid
- Division of Pharmacy and Pharmaceutical Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK.
| | - Saeed Afshin-Javid
- College of Engineering Design and Physical Sciences Tower D -203, Brunel University London, Uxbridge UB8 3PH, UK
| | - Charles C Horn
- Biobehavioral Oncology Program, University of Pittsburgh Cancer Institute, United States; Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, University of Pittsburgh School of Medicine, United States; Department of Anesthesiology, University of Pittsburgh School of Medicine, United States; Center for Neuroscience, University of Pittsburgh, United States
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Serafine KM, Rice KC, France CP. Directly Observable Behavioral Effects of Lorcaserin in Rats. J Pharmacol Exp Ther 2015; 355:381-5. [PMID: 26384326 PMCID: PMC4658489 DOI: 10.1124/jpet.115.228148] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/10/2015] [Indexed: 11/22/2022] Open
Abstract
(1R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine (lorcaserin) is approved by the United States Food and Drug Administration for treating obesity, and its therapeutic effects are thought to result from agonist activity at serotonin (5-HT)2C receptors. Lorcaserin has affinity for other 5-HT receptor subtypes, although its activity at those subtypes is not fully described. The current study compared the behavioral effects of lorcaserin (0.0032-32.0 mg/kg) to the effects of other 5-HT receptor selective agonists in rats (n = 8). The 5-HT2C receptor selective agonist 1-(3-chlorophenyl)piperazine (mCPP, 0.032-1.0 mg/kg) and lorcaserin induced yawning which was attenuated by the 5-HT2C receptor selective antagonist 6-chloro-5-methyl-N-(6-[(2-methylpyridin-3-yl)oxy]pydidin-3-yl)indoline-1-carboxamide (1.0 mg/kg). The 5-HT2A receptor selective agonist 2,5-dimethoxy-4-methylamphetamine (0.1-3.2 mg/kg) induced head twitching, which was attenuated by the 5-HT2A receptor selective antagonist R-(+)-2,3-dimethoxyphenyl-1-[2-(4-piperidine)-methanol] (MDL 100907, 0.01 mg/kg), lorcaserin (3.2 mg/kg), and mCPP (3.2 mg/kg). In rats pretreated with MDL 100907 (1.0 mg/kg), lorcaserin also induced head twitching. At larger doses, lorcaserin produced forepaw treading, which was attenuated by the 5-HT1A receptor selective antagonist N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-(2-pyridyl)cyclohexanecarboxamide (0.178 mg/kg). While the behavioral effects of lorcaserin in rats are consistent with it having agonist activity at 5-HT2C receptors, these data suggest that at larger doses it also has agonist activity at 5-HT2A and possibly 5-HT1A receptors. Mounting evidence suggests that 5-HT2C receptor agonists might be effective for treating drug abuse. A more complete description of the activity of lorcaserin at 5-HT receptor subtypes will facilitate a better understanding of the mechanisms that mediate its therapeutic effects.
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MESH Headings
- DOM 2,5-Dimethoxy-4-Methylamphetamine/pharmacology
- 8-Hydroxy-2-(di-n-propylamino)tetralin/pharmacology
- Amphetamines/pharmacology
- Animals
- Anti-Obesity Agents/pharmacology
- Behavior, Animal/drug effects
- Benzazepines/pharmacology
- Dose-Response Relationship, Drug
- Head Movements/drug effects
- Male
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT1A/drug effects
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2C/drug effects
- Serotonin 5-HT2 Receptor Agonists/pharmacology
- Serotonin 5-HT2 Receptor Antagonists/pharmacology
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Yawning/drug effects
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Affiliation(s)
- Katherine M Serafine
- Departments of Pharmacology (K.M.S., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, San Antonio, Texas and Chemical Biology Research Laboratory, Department of Health and Human Services, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland (K.C.R.)
| | - Kenner C Rice
- Departments of Pharmacology (K.M.S., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, San Antonio, Texas and Chemical Biology Research Laboratory, Department of Health and Human Services, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland (K.C.R.)
| | - Charles P France
- Departments of Pharmacology (K.M.S., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, San Antonio, Texas and Chemical Biology Research Laboratory, Department of Health and Human Services, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland (K.C.R.)
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Herth MM, Knudsen GM. Current radiosynthesis strategies for 5-HT2Areceptor PET tracers. J Labelled Comp Radiopharm 2015; 58:265-73. [DOI: 10.1002/jlcr.3288] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Matthias M. Herth
- Center for Integrated Molecular Brain Imaging; Rigshospitalet and University of Copenhagen; Blegdamsvej 9 Copenhagen DK-2100 Denmark
- Department of Drug Design and Pharmacology; University of Copenhagen; Jagtvej 160 Copenhagen DK-2100 Denmark
| | - Gitte M. Knudsen
- Center for Integrated Molecular Brain Imaging; Rigshospitalet and University of Copenhagen; Blegdamsvej 9 Copenhagen DK-2100 Denmark
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Cardinale J, Ermert J, Humpert S, Coenen HH. Iodonium ylides for one-step, no-carrier-added radiofluorination of electron rich arenes, exemplified with 4-(([18F]fluorophenoxy)-phenylmethyl)piperidine NET and SERT ligands. RSC Adv 2014. [DOI: 10.1039/c4ra00674g] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Iodonium ylide precursors of electron rich arenes, i.e. the NET and SERT ligands 4-((3- and 4-fluorophenoxy)phenylmethyl)piperidine, served as model compounds for the direct substitution with n.c.a. [18F]fluoride.
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Affiliation(s)
- Jens Cardinale
- Institut für Neurowissenschaften und Medizin
- INM-5: Nuklearchemie
- Forschungszentrum Jülich GmbH
- 52425 Jülich, Germany
- Department of Medical Physics in Radiology
| | - Johannes Ermert
- Institut für Neurowissenschaften und Medizin
- INM-5: Nuklearchemie
- Forschungszentrum Jülich GmbH
- 52425 Jülich, Germany
| | - Sven Humpert
- Institut für Neurowissenschaften und Medizin
- INM-5: Nuklearchemie
- Forschungszentrum Jülich GmbH
- 52425 Jülich, Germany
| | - Heinz H. Coenen
- Institut für Neurowissenschaften und Medizin
- INM-5: Nuklearchemie
- Forschungszentrum Jülich GmbH
- 52425 Jülich, Germany
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Development of novel chiral capillary electrophoresis methods for the serotonin receptor (5-HT2A) antagonist MDL 100,907 (volinanserin) and for its key intermediate compound. J Pharm Biomed Anal 2013; 88:579-83. [PMID: 24216279 DOI: 10.1016/j.jpba.2013.10.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/01/2013] [Accepted: 10/06/2013] [Indexed: 11/21/2022]
Abstract
Enantioselective capillary electrophoretic methods were elaborated for the determination of the enantiomeric purity of (R)-MDL 100,907 and its preparatively resolved key intermediate compound during the synthesis route. The pKa values of the intermediate compound and the end product determined by CE were 10.5±0.1 and 9.0±0.1, respectively. The enantiopurity of the intermediate compound can be monitored in fully protonated state by applying 15mM sulfobutylether-β-cyclodextrin at pH 5 when the peak belonging to the impurity migrates before the main component. The fact that the consecutive steps of the synthesis do not affect the enantiomeric purity was verified by the other, newly developed CE method. The enantiomers of rac-MDL 100,907 were resolved by 15mM carboxymethyl-γ-cyclodextrin at pH 3. The applicability (selectivity, LOD, LOQ, repeatability, precision and accuracy) of the methods was studied as well.
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12
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Li JX, Shah AP, Patel SK, Rice KC, France CP. Modification of the behavioral effects of morphine in rats by serotonin 5-HT₁A and 5-HT₂A receptor agonists: antinociception, drug discrimination, and locomotor activity. Psychopharmacology (Berl) 2013; 225:791-801. [PMID: 22993050 PMCID: PMC3549012 DOI: 10.1007/s00213-012-2870-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 08/28/2012] [Indexed: 11/29/2022]
Abstract
RATIONALE Indirect-acting serotonin (5-HT) receptor agonists can enhance the antinociceptive effects of morphine; however, the specific 5-HT receptor subtype(s) mediating this enhancement is not established. OBJECTIVE This study examined interactions between morphine and both 5-HT(1A) and 5-HT(2A) receptor agonists in rats using measures of antinociception (radiant heat tail flick and warm water tail withdrawal), drug discrimination (3.2 mg/kg morphine versus saline), and locomotion. METHODS Male Sprague-Dawley rats (n = 7-8 per group) were used to examine the effects of morphine alone and in combination with DOM (5-HT(2A) agonist) and 8-OH-DPAT (5-HT(1A) agonist). RESULTS DOM did not modify antinociceptive or discriminative stimulus effects while modestly attenuating locomotor-stimulating effects of morphine; the effect of DOM (0.32 mg/kg) on morphine-induced locomotion was prevented by the 5-HT(2A) receptor-selective antagonist MDL 100907. In contrast, 8-OH-DPAT (0.032-0.32 mg/kg) fully attenuated the antinociceptive effects (both procedures), did not modify the discriminative stimulus effects, and enhanced (0.32 mg/kg) the locomotor-stimulating effects of morphine. These effects of 8-OH-DPAT were prevented by the 5-HT(1A) receptor-selective antagonist WAY100635. CONCLUSION Agonists acting at 5-HT(1A) or 5-HT(2A) receptors do not modify all effects of mu opioid receptor agonists in a similar manner. Moreover, interactions between 5-HT and opioid receptor agonists vary significantly between rats and nonhuman primates, underscoring the value of comparing drug interactions across a broad range of conditions and in multiple species.
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Affiliation(s)
- Jun-Xu Li
- Corresponding author: Charles P France, Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900,
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Cunningham KA, Anastasio NC, Fox RG, Stutz SJ, Bubar MJ, Swinford SE, Watson CS, Gilbertson SR, Rice KC, Rosenzweig-Lipson S, Moeller FG. Synergism between a serotonin 5-HT2A receptor (5-HT2AR) antagonist and 5-HT2CR agonist suggests new pharmacotherapeutics for cocaine addiction. ACS Chem Neurosci 2013; 4:110-21. [PMID: 23336050 DOI: 10.1021/cn300072u] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 08/11/2012] [Indexed: 11/30/2022] Open
Abstract
Relapse to cocaine dependence, even after extended abstinence, involves a number of liability factors including impulsivity (predisposition toward rapid, unplanned reactions to stimuli without regard to negative consequences) and cue reactivity (sensitivity to cues associated with cocaine-taking which can promote cocaine-seeking). These factors have been mechanistically linked to serotonin (5-hydroxytryptamine, 5-HT) signaling through the 5-HT(2A) receptor (5-HT(2A)R) and 5-HT(2C)R; either a selective 5-HT(2A)R antagonist or a 5-HT(2C)R agonist suppresses impulsivity and cocaine-seeking in preclinical models. We conducted proof-of-concept analyses to evaluate whether a combination of 5-HT(2A)R antagonist plus 5-HT(2C)R agonist would have synergistic effects over these liability factors for relapse as measured in a 1-choice serial reaction time task and cocaine self-administration/reinstatement assay. Combined administration of a dose of the selective 5-HT(2A)R antagonist M100907 plus the 5-HT(2C)R agonist WAY163909, each ineffective alone, synergistically suppressed cocaine-induced hyperactivity, inherent and cocaine-evoked impulsive action, as well as cue- and cocaine-primed reinstatement of cocaine-seeking behavior. The identification of synergism between a 5-HT(2A)R antagonist plus a 5-HT(2C)R agonist to attenuate these factors important in relapse indicates the promise of a bifunctional ligand as an anti-addiction pharmacotherapeutic, setting the stage to develop new ligands with improved efficacy, potency, selectivity, and in vivo profiles over the individual molecules.
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Affiliation(s)
| | | | | | | | | | | | | | - Scott R. Gilbertson
- Department of Chemistry, University of Houston, Houston, Texas, , United States
| | - Kenner C. Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland, , United States
| | | | - F. Gerard Moeller
- Center for Neurobehavioral Research
on Addictions, Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center Houston,
Houston, Texas, , United States
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Hasegawa S, Fikre-Merid M, Diksic M. 5-HT2A receptor antagonist M100907 reduces serotonin synthesis: an autoradiographic study. Brain Res Bull 2012; 87:44-9. [PMID: 22056993 PMCID: PMC3653840 DOI: 10.1016/j.brainresbull.2011.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 10/19/2011] [Indexed: 11/16/2022]
Abstract
The effects of the administration of the serotonin (5-HT)(2A) antagonist, M100907, on 5-HT synthesis rates, were evaluated using the α-[(14)C]methyl-l-tryptophan (α-MTrp) autoradiographic method. In the treatment study, M100907 (10mg/kg) was injected intraperitoneally 30 min before the α-MTrp injection (30 μCi over 2 min). A single dose of M100907 caused a significant decrease in the synthesis in the anterior olfactory nucleus, accumbens nucleus, frontal cortex, sensory-motor cortex, cingulate cortex, medial caudate-putamen, dorsal thalamus, substantia nigra, inferior collicus, raphe magnus nucleus, superior olive, and raphe pallidus nucleus. These data suggest that the terminal 5-HT(2A) receptors are involved in the regulation of 5-HT synthesis in the entire brain. Further, 5-HT synthesis is likely regulated by the 5-HT(2A) antagonistic property of M100907 in the cortices, anterior olfactory nucleus, caudate putamen, and nucleus accumbens.
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Affiliation(s)
| | - Maraki Fikre-Merid
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
| | - Mirko Diksic
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
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15
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Shashack MJ, Cunningham KA, Seitz PK, McGinnis A, Smith TD, Watson CS, Gilbertson SR. Synthesis and evaluation of dimeric derivatives of 5-HT(2A) receptor (5-HT(2A)R) antagonist M-100907. ACS Chem Neurosci 2011; 2:640-644. [PMID: 22247793 DOI: 10.1021/cn200077q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
It is now well accepted that at least some serotonin receptors exist in dimeric and oligmeric forms. The linking of receptor ligands has been shown to have potential in the development of selective agonists and antagonists for traditionally refractive receptors. Here we report the development of a dimeric version of the known 5-HT(2A)R antagonist, M-100907. Derivatives of M-100907 were synthesized to determine an appropriate site for the linker connection. Then, homodimers with polyether linkers of different lengths were functionally tested in a bioassay to determine the optimal linker length. Attachment at the catechol of M-100907 with linkers between 12 and 18 atoms in length proved to be optimal.
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Affiliation(s)
- Matthew J. Shashack
- Department of Pharmacology and Toxicology, Center for Addiction Research, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0615, United States
| | - Kathryn A. Cunningham
- Department of Pharmacology and Toxicology, Center for Addiction Research, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0615, United States
| | - Patricia K. Seitz
- Department of Pharmacology and Toxicology, Center for Addiction Research, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0615, United States
| | - Andrew McGinnis
- Department of Pharmacology and Toxicology, Center for Addiction Research, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0615, United States
| | - Thressa D. Smith
- Department of Pharmacology and Toxicology, Center for Addiction Research, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0615, United States
| | - Cheryl S. Watson
- Department of Biochemistry and Molecular Biology, Center for Addiction Research, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0647, United States
| | - Scott R. Gilbertson
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States
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16
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Schmitt U, Lee DE, Herth MM, Piel M, Buchholz HG, Roesch F, Hiemke C, Lueddens H, Debus F. P-glycoprotein influence on the brain uptake of a 5-HT(2A) ligand: [(18)F]MH.MZ. Neuropsychobiology 2011; 63:183-90. [PMID: 21304228 DOI: 10.1159/000321594] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 09/27/2010] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS The serotonergic system, especially the 5-HT(2A) receptor, is involved in various diseases and conditions. We have recently developed a new [(18)F]-5-HT(2A) receptor ligand using an analogue, MDL 100907, as a basis for molecular imaging with positron emission tomography. This tracer, [(18)F]MH.MZ, has been shown to be an adequate tool to visualize the 5-HT(2A) receptors in vivo. However, [(18)F]altanserin, similar in chemical structure, is a substrate of efflux transporters, such as P-glycoprotein (P-gp), of the blood-brain barrier, thus limiting its availability in the central nervous system. The aim of this study was to determine whether transport by P-gp influences the distribution ratio of [(18)F]MH.MZ in the frontal cortex. METHODS The approach was based on P-gp knockout mice which were compared with wild-type mice under several conditions. In vivo pharmacokinetic and microPET investigations were carried out. RESULTS All analyses showed that [(18)F]MH.MZ entered the brain and was sensitive to P-gp transport. In P-gp knockout mice, brain concentrations of MH.MZ were about 5-fold higher than in wild-type animals which is reflected by a 2-fold increase in standardized uptake values of [(18)F]MH.MZ in the frontal cortex of P-gp knockout mice. CONCLUSION Our results give evidence for a functional role of transport mechanisms at the blood-brain barrier, specifically of P-gp, and its subregional distribution. Investigation of these mechanisms will benefit the development of more efficient radioligands and drugs for molecular imaging and pharmacotherapy of the mentally ill.
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Affiliation(s)
- Ulrich Schmitt
- Institute of Nuclear Chemistry, Johannes Gutenberg University Mainz, Mainz, Germany.
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17
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Effects of direct- and indirect-acting serotonin receptor agonists on the antinociceptive and discriminative stimulus effects of morphine in rhesus monkeys. Neuropsychopharmacology 2011; 36:940-9. [PMID: 21209613 PMCID: PMC3077263 DOI: 10.1038/npp.2010.232] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Serotonergic (5-HT) systems modulate pain, and drugs acting on 5-HT systems are used with opioids to treat pain. This study examined the effects of 5-HT receptor agonists on the antinociceptive and discriminative stimulus effects of morphine in monkeys. Morphine increased tail-withdrawal latency in a dose-related manner; 5-HT receptor agonists alone increased tail-withdrawal latency at 50 °C but not 55 °C water. The antinociceptive effects of morphine occurred with smaller doses when monkeys received an indirect-acting (fenfluramine) or direct acting (8-OH-DPAT, F13714, buspirone, quipazine, DOM, and 2C-T-7) agonist. The role of 5-HT receptor subtypes in these interactions was confirmed with selective 5-HT(1A) (WAY100635) and 5-HT(2A) (MDL100907) receptor antagonists. None of the 5-HT drugs had morphine-like discriminative stimulus effects; however, fenfluramine and 5-HT(2A) receptor agonists attenuated the discriminative stimulus effects of morphine and this attenuation was prevented by MDL100907. The 5-HT(1A) receptor agonists did not alter the discriminative stimulus effects of morphine. Thus, 5-HT receptor agonists increase the potency of morphine in an assay of antinociception, even under conditions where 5-HT agonists are themselves without effect (ie, 55 °C water), without increasing (and in some cases decreasing) the potency of morphine in a drug discrimination assay. Whereas 5-HT(2A) receptor agonists increase the potency of morphine for antinociception at doses that have no effect on the rate of operant responding, 5-HT(1A) receptor agonists increase the potency of morphine only at doses that eliminate operant responding. These data suggest that drugs acting selectively on 5-HT receptor subtypes could help to improve the use of opioids for treating pain.
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Effects of serotonin (5-HT)1A and 5-HT2A receptor agonists on schedule-controlled responding in rats: drug combination studies. Psychopharmacology (Berl) 2011; 213:489-97. [PMID: 21174080 PMCID: PMC4144073 DOI: 10.1007/s00213-010-2136-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 12/02/2010] [Indexed: 10/18/2022]
Abstract
RATIONALE Indirect-acting serotonin (5-HT) receptor agonists (e.g., selective 5-HT reuptake inhibitors [SSRI]) stimulate multiple 5-HT receptors, although the role of particular receptors as well as interaction(s) among different receptors in the therapeutic effects of SSRIs is not fully understood. OBJECTIVES Relatively few studies have systematically examined direct-acting agonists in combination. This study examined the 5-HT(1A) receptor agonists 8-hydroxy-2-(di-n-propylamino) tetralin hydrochloride (8-OH-DPAT; 0.01-10.0 mg/kg) and 3-chloro-4-fluorophenyl-4-fluoro-4-([(5-methyl-6-methylamino-pyridin-2-ylmethyl)-amino]-methyl)-piperidin-1-yl-methanone (F13714; 0.01-1.0 mg/kg) and the 5-HT(2A) receptor agonists 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM; 0.32-10.0 mg/kg) and dipropyltryptamine (DPT; 1.0-32.0 mg/kg), alone and in combination, in rats responding under a fixed ratio schedule of food presentation. RESULTS When administered alone, each drug decreased the rate of responding in a dose-related manner with the potency order being F13714 > 8-OH-DPAT > DOM > DPT. WAY100635 (5-HT(1A) receptor antagonist; 0.01-0.1 mg/kg) attenuated the rate-decreasing effects of 8-OH-DPAT and F13714 while MDL100907 (5-HT(2A) receptor antagonist; 0.01-0.1 mg/kg) attenuated the rate-decreasing effects of DOM and DPT. Dose addition analysis showed that the interaction between 8-OH-DPAT and F13714, as well as the interaction between DOM and DPT, was additive. In contrast, the interaction between 8-OH-DPAT and DOM, as well as the interaction between F13714 and DOM, was infra-additive. CONCLUSIONS This study shows that for some dose combinations, agonist actions at one 5-HT receptor subtype attenuate agonist actions at another 5-HT receptor subtype; thus, the combined neuropharmacological actions and therapeutic effects of indirect-acting agonists are not likely to be adequately characterized by examining in isolation activity at particular 5-HT receptor subtypes.
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Kramer V, Herth MM, Santini MA, Palner M, Knudsen GM, Rösch F. Research Letter: Structural Combination of Established 5-HT2A Receptor Ligands: New Aspects of the Binding Mode. Chem Biol Drug Des 2010; 76:361-6. [DOI: 10.1111/j.1747-0285.2010.01011.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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Li JX, Koek W, Rice KC, France CP. Differential effects of serotonin 5-HT1A receptor agonists on the discriminative stimulus effects of the 5-HT2A receptor agonist 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane in rats and rhesus monkeys. J Pharmacol Exp Ther 2010; 333:244-52. [PMID: 20053932 PMCID: PMC2846017 DOI: 10.1124/jpet.109.163451] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 01/05/2010] [Indexed: 11/22/2022] Open
Abstract
Although many drugs act by indirectly stimulating multiple receptors (e.g., reuptake inhibitors), relatively little is known about interactions between agonism at different receptors. This study compared the effect of serotonin (5-HT)(1A) receptor agonists with the discriminative stimulus effects of the 5-HT(2A) receptor agonist 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) in rats and rhesus monkeys. Eight rats discriminated 0.56 mg/kg i.p. DOM and responded under a fixed ratio (FR) 10 schedule of food presentation, whereas three rhesus monkeys discriminated 0.32 mg/kg s.c. DOM and responded under an FR 5 schedule of stimulus shock termination. DOM and the 5-HT(2A) receptor agonists 2,5-dimethoxy-4-n-propylthiophenethylamine (2C-T-7) and dipropyltryptamine (DPT), but not the 5-HT(1A) receptor agonists 8-hydroxy-2-(di-n-propylamino) tetralin hydrochloride (8-OH-DPAT) and 3-chloro-4-fluorophenyl-(4-fluoro-4-([(5-methyl-6-methylaminopyridin-2-ylmethyl) amino) methyl] piperidin-1-yl) methanone (F13714), occasioned responding on the DOM-associated lever in rats and monkeys. Both 8-OH-DPAT and F13714 attenuated the discriminative stimulus effects of DOM in monkeys but not in rats; these effects of 8-OH-DPAT and F13714 were prevented by the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (WAY 100635). DPT and 2C-T-7 enhanced the discriminative stimulus effects of DOM in rats and monkeys in an additive manner. Taken together, the results suggest that the DOM discriminative stimulus is pharmacologically similar and mediated by 5-HT(2A) receptors in rats and monkeys; however, the ability of 5-HT(1A) receptor agonists to modify the effects of DOM is markedly different between these species. These results indicate possible differences in the neurobiology of 5-HT systems that could be important for studying drugs that have multiple mechanisms of action (e.g., reuptake inhibitors that indirectly stimulate multiple receptors).
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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21
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Li JX, Unzeitig A, Javors MA, Rice KC, Koek W, France CP. Discriminative stimulus effects of 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM), ketanserin, and (R)-(+)-{alpha}-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-pipidinemethanol (MDL100907) in rats. J Pharmacol Exp Ther 2009; 331:671-9. [PMID: 19687292 PMCID: PMC2775261 DOI: 10.1124/jpet.109.157560] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 08/14/2009] [Indexed: 11/22/2022] Open
Abstract
Very little is known about constitutive activity in vivo. This study examined whether constitutive activity and inverse agonism contribute to discriminative stimulus effects of drugs acting at serotonin (5-HT)(2A) receptors. Rats were trained to discriminate between saline and either 0.56 mg/kg 5-HT(2) receptor agonist 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM), 1.0 mg/kg 5-HT(2A) receptor antagonist ketanserin, or 0.1 mg/kg purported 5-HT(2A) receptor inverse agonist (R)-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-pipidinemethanol (MDL100907). Discriminative control was established with each drug after 33 to 35 sessions. MDL100907 and ketanserin did not occasion DOM lever responding but attenuated the discriminative stimulus effects of DOM. DOM did not occasion responding on the drug-associated lever in rats discriminating MDL100907 or ketanserin, but attenuated the discriminative stimulus effects of both drugs. Ketanserin and ritanserin occasioned MDL100907-lever responding, whereas rats discriminating ketanserin responded only partially on the drug-associated lever after receiving MDL100907, ritanserin, or the alpha(1)-adrenergic antagonist prazosin. Combining prazosin with MDL100907 or ritanserin resulted in near-complete ketanserin-lever responding, indicating that the ketanserin stimulus involves both 5-HT(2A) and alpha(1)-adrenergic receptors. Administration of p-chlorophenylalanine methyl ester, then fenfluramine, significantly decreased cortical 5-HT, enhanced sensitivity to the discriminative stimulus effects of DOM, and occasioned partial MDL100907-lever responding. Collectively, these results show that DOM and MDL100907 discriminative stimulus effects are mediated by 5-HT(2A) receptors and that ketanserin discriminative stimulus effects involve both 5-HT(2A) and alpha(1)-adrenergic receptors. Results in 5-HT-depleted rats further suggest that the discriminative stimulus effects of MDL100907 might involve antagonism of endogenous 5-HT and/or inverse agonism at 5-HT(2A) receptors.
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MESH Headings
- DOM 2,5-Dimethoxy-4-Methylamphetamine/pharmacology
- Analgesics, Opioid/pharmacology
- Anesthetics, Dissociative/pharmacology
- Animals
- Conditioning, Operant/drug effects
- Discrimination, Psychological/drug effects
- Dose-Response Relationship, Drug
- Excitatory Amino Acid Antagonists/pharmacology
- Fluorobenzenes/pharmacology
- Ketamine/pharmacology
- Ketanserin/pharmacology
- Male
- Morphine/pharmacology
- Phencyclidine/pharmacology
- Piperidines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptors, Adrenergic, alpha-1/drug effects
- Ritanserin/pharmacology
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, TX 78229, USA
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22
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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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23
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Synthesis and in vitro affinities of various MDL 100907 derivatives as potential 18F-radioligands for 5-HT2A receptor imaging with PET. Bioorg Med Chem 2009; 17:2989-3002. [PMID: 19329329 DOI: 10.1016/j.bmc.2009.03.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 03/06/2009] [Accepted: 03/11/2009] [Indexed: 11/24/2022]
Abstract
Radiolabelled piperidine derivatives such as [(11)C]MDL 100907 and [(18)F]altanserin have played an important role in diagnosing malfunction in the serotonergic neurotransmission. A variety of novel piperidine MDL 100907 derivatives, possible to label with (18)F-fluorine, were synthesized to improve molecular imaging properties of [(11)C]MDL 100907. Their in vitro affinities to a broad spectrum of neuroreceptors and their lipophilicities were determined and compared to the clinically used reference compounds MDL 100907 and altanserin. The novel compounds MA-1 (53) and (R)-MH.MZ (56) show K(i)-values in the nanomolar range towards the 5-HT(2A) receptor and insignificant binding to other 5-HT receptor subtypes or receptors. Interestingly, compounds MA-1 (53), MH.MZ (55) and (R)-MH.MZ (56) provide a receptor selectivity profile similar to MDL 100907. These compounds could possibly be preferable antagonistic (18)F-tracers for visualization of the 5-HT(2A) receptor status. Medium affine compounds (VK-1 (32), (51), (52), (54)) were synthesized and have K(i) values between 30 and 120 nM. All promising compounds show logP values between 2 and 3, that is, within the range of those for the established radiotracers altanserin and MDL 100907. The novel compounds MA-1 (53) and (R)-MH.MZ (56) thus appear to be promising high affine and selective tracers of (18)F-labelled analogues for 5-HT(2A) imaging with PET.
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Li JX, Rice KC, France CP. Discriminative stimulus effects of 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane in rhesus monkeys: antagonism and apparent pA2 analyses. J Pharmacol Exp Ther 2009; 328:976-81. [PMID: 19098164 PMCID: PMC2682264 DOI: 10.1124/jpet.108.145458] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Accepted: 12/15/2008] [Indexed: 11/22/2022] Open
Abstract
Discriminative stimulus effects of the serotonin (5-HT) receptor agonist 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) have been studied in rats and, more recently, in rhesus monkeys. This study examined DOM, 2,5-dimethoxy-4-(n)-propylthiophenethylamine (2C-T-7), and dipropyltryptamine hydrochloride (DPT) alone and in combination with three antagonists, MDL100907 [(+/-)2,3-dimethoxyphenyl-1-[2-(4-piperidine)-methanol]], ketanserin [3-[2-[4-(4-fluorobenzoyl)piperidin-1-yl]ethyl]-1H-quinazoline-2,4-dione], and ritanserin [6-[2-[4-[bis(4-fluorophenyl)methylidene]piperidin-1-yl]ethyl]-7-methyl-[1,3]thiazolo[2,3-b]pyrimidin-5-one], to identify the 5-HT receptor subtype(s) that mediates the discriminative stimulus effects of these 5-HT receptor agonists. Four adult rhesus monkeys discriminated between 0.32 mg/kg s.c. DOM and vehicle while responding under a fixed ratio 5 schedule of stimulus shock termination. DOM, 2C-T-7, and DPT dose-dependently increased responding on the DOM-associated lever. MDL100907 (0.001-0.01 mg/kg), ketanserin (0.01-0.1 mg/kg), and ritanserin (0.01-0.1 mg/kg) each shifted the dose-response curves of DOM, 2C-T-7, and DPT rightward in a parallel manner. Schild analysis of each drug combination was consistent with a simple, competitive, and reversible interaction. Similar apparent affinity (pA(2)) values were obtained for MDL100907 in combination with DOM (8.61), 2C-T-7 (8.58), or DPT (8.50), for ketanserin with DOM (7.67), 2C-T-7 (7.75), or DPT (7.71), and for ritanserin with DOM (7.65), 2C-T-7 (7.75), or DPT (7.65). Potency of antagonists in this study was correlated with binding affinity at 5-HT(2A) receptors and not at 5-HT(2C) or alpha(1) adrenergic receptors. This study used Schild analysis to examine receptor mechanisms mediating the discriminative stimulus effects of hallucinogenic drugs acting at 5-HT receptors; results provide quantitative evidence for the predominant, if not exclusive, role of 5-HT(2A) receptors in the discriminative stimulus effects of DOM, 2C-T-7, and DPT in rhesus monkeys.
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
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May JA, Sharif NA, Chen HH, Liao JC, Kelly CR, Glennon RA, Young R, Li JX, Rice KC, France CP. Pharmacological properties and discriminative stimulus effects of a novel and selective 5-HT2 receptor agonist AL-38022A [(S)-2-(8,9-dihydro-7H-pyrano[2,3-g]indazol-1-yl)-1-methylethylamine]. Pharmacol Biochem Behav 2009; 91:307-14. [PMID: 18718483 PMCID: PMC3763814 DOI: 10.1016/j.pbb.2008.07.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Revised: 07/18/2008] [Accepted: 07/23/2008] [Indexed: 11/26/2022]
Abstract
AL-38022A is a novel synthetic serotonergic (5-HT) ligand that exhibited high affinity for each of the 5-HT2 receptor subtypes (Ki100-fold less) affinity for other 5-HT receptors. In addition, AL-38022A displayed a very low affinity for a broad array of other receptors, neurotransmitter transport sites, ion channels, and second messenger elements, making it a relatively selective agent. AL-38022A potently stimulated functional responses via native and cloned rat (EC50 range: 1.9-22.5 nM) and human (EC50 range: 0.5-2.2 nM) 5-HT2 receptor subtypes including [Ca2+]i mobilization and tissue contractions with apparently similar potencies and intrinsic activities and was a full agonist at all 5-HT2 receptor subtypes. The CNS activity of AL-38022A was assessed by evaluating its discriminative stimulus effects in both a rat and a monkey drug discrimination paradigm using DOM as the training drug. AL-38022A fully generalized to the DOM stimulus in each of these studies; in monkeys MDL 100907 antagonized both DOM and AL-38022A. The pharmacological profile of AL-38022A suggests that it could be a useful tool in defining 5-HT2 receptor signaling and receptor characterization where 5-HT may function as a neurotransmitter.
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MESH Headings
- DOM 2,5-Dimethoxy-4-Methylamphetamine/pharmacology
- Adrenergic beta-2 Receptor Agonists
- Animals
- Benzopyrans/pharmacology
- Calcium Signaling/drug effects
- Chemistry, Physical
- Cloning, Molecular
- Cyclic AMP/biosynthesis
- Cyclic AMP/genetics
- Discrimination, Psychological/drug effects
- Dose-Response Relationship, Drug
- Drug Stability
- Fluorobenzenes/pharmacology
- Humans
- In Vitro Techniques
- Indazoles/pharmacology
- Macaca mulatta
- Male
- Piperidines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2C/drug effects
- Serotonin 5-HT2 Receptor Agonists
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/chemistry
- Serotonin Receptor Agonists/pharmacology
- Stomach/drug effects
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Affiliation(s)
- Jesse A May
- Ophthalmology Discovery Research, Alcon Research, Ltd., 6201 South Freeway, Fort Worth, Texas 76134, United States.
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26
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Mühlhausen U, Ermert J, Herth MM, Coenen HH. Synthesis, radiofluorination and first evaluation of (±)-[18F]MDL 100907 as serotonin 5-HT2Areceptor antagonist for PET. J Labelled Comp Radiopharm 2009. [DOI: 10.1002/jlcr.1563] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Total synthesis and evaluation of [18F]MHMZ. Bioorg Med Chem Lett 2007; 18:1515-9. [PMID: 18187324 DOI: 10.1016/j.bmcl.2007.12.054] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 11/27/2007] [Accepted: 12/20/2007] [Indexed: 11/22/2022]
Abstract
Radiochemical labeling of MDL 105725 using the secondary labeling precursor 2-[(18)F]fluoroethyltosylate ([(18)F]FETos) was carried out in yields of approximately 90% synthesizing [(18)F]MHMZ in a specific activity of approximately 50MBq/nmol with a starting activity of approximately 3GBq. Overall radiochemical yield including [(18)F]FETos synthon synthesis, [(18)F]fluoroalkylation and preparing the injectable [(18)F]MHMZ solution was 42% within a synthesis time of approximately 100 min. The novel compound showed excellent specific binding to the 5-HT(2A) receptor (K(i)=9.0 nM) in vitro and promising in vivo characteristics.
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Li JX, Rice KC, France CP. Behavioral effects of dipropyltryptamine in rats: evidence for 5-HT1A and 5-HT2A agonist activity. Behav Pharmacol 2007; 18:283-8. [PMID: 17551320 DOI: 10.1097/fbp.0b013e3281f19ca0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
These studies investigated the role of serotonin-1A (5-HT1A) and 5-HT2A receptors in the behavioral effects of dipropyltryptamine (DPT). Eight rats discriminated 0.56 mg/kg 2,5-dimethoxy-4-methylamphetamine (DOM) from saline and responded under a fixed ratio 5 schedule of food presentation; 12 other rats were used for observational studies. DOM and DPT increased responding on the DOM lever with 3.2 mg/kg DPT producing greater than 95% responding on the DOM lever; this effect of DPT was antagonized by the 5-HT2A receptor antagonist MDL100907. In another study, the 5-HT1A and 5-HT7 receptor agonist 8-OH-DPAT produced lower-lip retraction and, at larger doses, flat body posture; DPT alone produced flat body posture and not lower-lip retraction; MDL100907 alone did not produce either effect. Pretreatment with DPT blocked 8-OH-DPAT-elicited lower-lip retraction, suggesting antagonist activity of DPT at 5-HT1A receptors; however, in the presence of MDL100907 DPT produced not only flat body posture but also lower-lip retraction, suggesting that agonist activity of DPT at 5-HT2A receptors masked agonist activity at 5-HT1A receptors. Lower-lip retraction and flat body posture by DPT in the presence of MDL100907 were attenuated by the 5-HT1A receptor antagonist WAY100635. These findings suggest that DPT has agonist activity at 5-HT1A and 5-HT2A receptors and that effects at 5-HT2A receptors mask effects at 5-HT1A receptors.
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA
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29
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Morris DJ, Hayes AM, Wills M. The “Reverse-Tethered” Ruthenium (II) Catalyst for Asymmetric Transfer Hydrogenation: Further Applications. J Org Chem 2006; 71:7035-44. [PMID: 16930059 DOI: 10.1021/jo061154l] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The attachment of a tethering group from the basic nitrogen atom to the arene ligand of a ruthenium(II) catalyst greatly improves its ability to catalyze asymmetric transfer hydrogenation (ATH) reactions. In this paper, we describe further applications of this versatile system to an extended substrate range.
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Affiliation(s)
- David J Morris
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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30
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Taylor JL, Bishop C, Ullrich T, Rice KC, Walker PD. Serotonin 2A receptor antagonist treatment reduces dopamine D1 receptor-mediated rotational behavior but not L-DOPA-induced abnormal involuntary movements in the unilateral dopamine-depleted rat. Neuropharmacology 2006; 50:761-8. [PMID: 16434065 DOI: 10.1016/j.neuropharm.2005.12.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 11/09/2005] [Accepted: 12/06/2005] [Indexed: 10/25/2022]
Abstract
Previous experiments have demonstrated that serotonin (5-HT) 2A receptor antagonists suppress hyperkinetic behaviors associated with dopamine (DA) D1 receptor supersensitivity in rats with 6-hydroxydopamine (6-OHDA) lesions. Since l-DOPA induced dyskinesia (LID) may be mediated by over-sensitive D1-mediated signaling, the present study examined the effects of the selective 5-HT2A antagonist M100907 on LID behaviors in DA-depleted rats. Adult male Sprague-Dawley rats with unilateral 6-OHDA lesions received daily l-DOPA treatments to produce dyskinetic behaviors as measured by abnormal involuntary movements (AIMs) testing. In these animals, M100907 (0.01, 0.1 or 1.0mg/kg, ip) given 30 min before l-DOPA did not alter the appearance or intensity of AIMs behaviors. Because l-DOPA induced AIMs in rats are dependent upon D1 and D2 receptor activation, a second study was performed to determine if M100907 could suppress D1- or D2-mediated rotational behaviors. Contralateral rotations induced by the D1 agonist SKF82958 were significantly reduced by pre-treatment with M100907. However, M100907 was ineffective in reducing rotations induced by the D2 agonist quinpirole. The finding that M100907 suppresses rotations induced by D1, but not D2, agonists may provide a partial explanation for the lack of effect of a selective 5-HT2A antagonist on l-DOPA-induced AIMs behaviors.
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Affiliation(s)
- Jennifer L Taylor
- Cellular and Clinical Neurobiology Program, Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
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31
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Villalobos C, Beique JC, Gingrich JA, Andrade R. Serotonergic regulation of calcium-activated potassium currents in rodent prefrontal cortex. Eur J Neurosci 2006; 22:1120-6. [PMID: 16176353 DOI: 10.1111/j.1460-9568.2005.04307.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In spite of a growing understanding of the actions of 5-hydroxytryptamine (5-HT) in the prefrontal cortex, the specific cellular mechanism used by 5-HT in this region remains poorly understood. Previous studies have shown that 5-HT inhibits the after hyper-polarization that follows a burst of spikes in pyramidal neurons. In the present study, we have used whole cell recordings in rat and mouse brain slices to re-examine this phenomenon with special emphasis on identifying the 5-HT receptor subtypes mediating this effect. Layer V pyramidal neurons display complex after hyper-polarizations that are mediated predominantly by calcium-activated potassium channels and involve two distinct currents known as medium after hyper-polarizating current and slow after hyper-polarizating current (I(sAHP)). Administration of 5-HT reduced the current underlying these after hyper-polarizations by selectively inhibiting I(sAHP). Pharmacological analysis of this response indicates that the main receptor responsible for this inhibition belongs to the 5-HT(2A) subtype. Thus, alpha-methyl-5-HT and 2,5-dimethoxy-4-bromoamphetamine (DOB) mimic the effect of 5-HT and the effect of these agonists is blocked by MDL 100 907. Similarly, administration of alpha-methyl-5-HT is without effect in slices derived from 5-HT(2A) receptor knockout mice. However, 5-HT(2A) receptor blockade only partially suppressed the ability of 5-HT to inhibit I(sAHP). This suggests the involvement of at least one more receptor subtype in this response. Consistent with this idea, administration of 5-carboxyamido-tryptamine, an agonist exhibiting no detectable affinity for 5-HT(2A) receptors, was also capable of suppressing I(sAHP). These results identify 5-HT(2A) receptors as being primarily involved in mediating the 5-HT-induced inhibition of I(sAHP) in prefrontal cortex, while also recognizing a contribution by an additional 5-HT receptor subtype.
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Affiliation(s)
- Claudio Villalobos
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
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32
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Winter JC, Kieres AK, Zimmerman MD, Reissig CJ, Eckler JR, Ullrich T, Rice KC, Rabin RA, Richards JB. The stimulus properties of LSD in C57BL/6 mice. Pharmacol Biochem Behav 2005; 81:830-7. [PMID: 16005500 PMCID: PMC1351004 DOI: 10.1016/j.pbb.2005.05.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 02/07/2005] [Accepted: 05/19/2005] [Indexed: 11/22/2022]
Abstract
RATIONALE Drug-induced stimulus control has proven to be a powerful tool for the assessment of a wide range of psychoactive drugs. Although a variety of species has been employed, the majority of studies have been in the rat. However, with the development of techniques which permit the genetic modification of mice, the latter species has taken on new importance. Lysergic acid diethylamide [LSD], the prototypic indoleamine hallucinogen, has not previously been trained as a discriminative stimulus in mice. OBJECTIVE To demonstrate the feasibility of LSD-induced stimulus control in the mouse and to provide a preliminary characterization of the stimulus properties of LSD in that species. METHODS Male C57BL/6 mice were trained using a left or right nose-poke operant on a fixed ratio 10, water reinforced task following the injection of lysergic acid diethylamide [LSD, 0.17 or 0.30 mg/kg, s.c.; 15 min pretreatment] or vehicle. RESULTS Stimulus control was established in 6 of 16 mice at a dose of LSD of 0.17 mg/kg after 39 sessions. An increase in dose to 0.30 mg/kg for the remaining mice resulted in stimulus control in an additional 5 subjects. In the low dose group, subsequent experiments demonstrated an orderly dose-effect relationship for LSD and a rapid offset of drug action with an absence of LSD effects 60 min after injection. When LSD [0.17 mg/kg] was administered in combination with the selective 5-HT2A antagonist, M100907, LSD-appropriate responding was significantly but incompletely reduced to approximately 50%; concurrently, response rates declined significantly. In mice trained with a dose of LSD of 0.30 mg/kg, full generalization to the phenethylamine hallucinogen, [-]-2,5-dimethoxy-4-methylamphetamine [DOM] was observed. CONCLUSIONS The present data demonstrate the feasibility of LSD-induced stimulus control in the mouse. The general features of stimulus control by LSD in the mouse closely resemble those observed in the rat but the present data suggest that there may be significant differences as well.
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Affiliation(s)
- J C Winter
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, 102 Farber Hall, Buffalo, NY 14214-3000, USA.
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33
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Bishop C, Tessmer JL, Ullrich T, Rice KC, Walker PD. Serotonin 5-HT2A Receptors Underlie Increased Motor Behaviors Induced in Dopamine-Depleted Rats by Intrastriatal 5-HT2A/2C Agonism. J Pharmacol Exp Ther 2004; 310:687-94. [PMID: 15044557 DOI: 10.1124/jpet.104.066365] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gene expression studies have suggested that dopamine (DA) depletion increases the sensitivity of striatal direct pathway neurons to the effects of serotonin (5-HT) via the 5-HT(2) receptor. The present study examined the possible influence(s) of 5-HT(2A) or 5-HT(2C) receptor-mediated signaling locally within the striatum on motor behavior triggered by 5-HT(2) receptor agonism in the neonatal DA-depleted rat. Male Sprague-Dawley rats were treated with 6-hydroxydopamine (6-OHDA; 60 microg in 5 microl per lateral ventricle) on postnatal day 3 to achieve near-total DA depletion bilaterally. Sixty days later, sham-operated (saline-injected) or 6-OHDA-treated rats were challenged with the 5-HT(2A/2C) agonist DOI [(+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane] or saline either by systemic treatment or bilateral intrastriatal infusion. Motor behavior was quantified for 60 min after agonist injection using computerized activity monitors. Systemic DOI treatment (0.2 or 2.0 mg/kg i.p.) was more effective in inducing motor activity in the DA-depleted group compared with intact controls. Intrastriatal DOI infusion (1.0 or 10.0 microg/side) also produced a significant rise in motor activity in the DA-depleted group during the 30- to 60-min period of behavioral analysis but did not influence behavior in intact animals. The effects of intrastriatal DOI infusion were blocked by intrastriatal coinfusion of the 5-HT(2) antagonist ketanserin (1.0 microg) and the 5-HT(2A)-preferring antagonist M100907 [(R)(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol; 1.0 microg] but not the 5-HT(2C)-preferring antagonist RS102221 [8-[5-(2,4-dimethoxy-5-(4-trifluoromethylsulfo-amido)phenyl-5-oxopentyl]-1,3,8-triazaspiro[4.5]decane-2,4-dione; 1.0 microg]. Such results support the hypothesis that 5-HT(2A) receptor-mediated signaling events are strengthened within the striatum under conditions of DA depletion to provide a more potent regulation of motor activity.
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Affiliation(s)
- Christopher Bishop
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, USA
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May JA, McLaughlin MA, Sharif NA, Hellberg MR, Dean TR. Evaluation of the ocular hypotensive response of serotonin 5-HT1A and 5-HT2 receptor ligands in conscious ocular hypertensive cynomolgus monkeys. J Pharmacol Exp Ther 2003; 306:301-9. [PMID: 12676887 DOI: 10.1124/jpet.103.049528] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Published investigations of serotonin-1A (5-hydroxytryptamine1A; 5-HT1A) receptor agonists and serotonin-2A (5-hydroxytryptamine2A; 5-HT2A) receptor antagonists in nonprimate species provide conflicting results with regard to their intraocular pressure-lowering efficacy. Thus, their therapeutic utility in the treatment of human glaucoma has been confusing. We evaluated the effect of selected 5-HT1A agonists and 5-HT2A receptor antagonists on intraocular pressure in a nonhuman primate model, the conscious cynomolgus monkey with laser-induced ocular hypertension. Neither selective 5-HT1A agonists [e.g., R-8-hydroxy-2-(di-n-propylamino)tetralin and flesinoxan] nor selective 5-HT2 receptor antagonists [e.g., R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol (M-100907) and 6-chloro-2,3-dihydro-5-methyl-N-[6-[(2-methyl-3-pyridinyl)oxy]-3-pyridinyl]-1H-indole-1-carboxamide (SB-242084)] lowered intraocular pressure in the primate model following topical ocular administration. However, compounds that function as agonists at both the 5-HT1A and 5-HT2 receptors were found to effectively lower intraocular pressure in the model: 5-hydroxy-alpha-methyltryptamine, 5-methoxy-alpha-methyltryptamine, 5-hydroxy-N,N-dimethyltryptamine (bufotenine), and 5-methoxy-N,N-dimethyltryptamine. Furthermore, the selective 5-HT2 receptor agonist R-(-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane lowered intraocular pressure in the primate model, demonstrating a pharmacological response associated with activation of the 5-HT2 receptor. These observations suggest that compounds that function as efficient agonists at 5-HT2 receptors should be considered as potential agents for the control of intraocular pressure in the treatment of ocular hypertension and glaucoma in humans.
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Affiliation(s)
- Jesse A May
- Ophthalmic Products Research, Alcon Research, Ltd., 6201 South Freeway, Ft. Worth, TX 76134, USA.
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