1
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Varty GB, Canal CE, Mueller TA, Hartsel JA, Tyagi R, Avery K, Morgan ME, Reichelt AC, Pathare P, Stang E, Palfreyman MG, Nivorozhkin A. Synthesis and Structure-Activity Relationships of 2,5-Dimethoxy-4-Substituted Phenethylamines and the Discovery of CYB210010: A Potent, Orally Bioavailable and Long-Acting Serotonin 5-HT 2 Receptor Agonist. J Med Chem 2024; 67:6144-6188. [PMID: 38593423 DOI: 10.1021/acs.jmedchem.3c01961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Structure-activity studies of 4-substituted-2,5-dimethoxyphenethylamines led to the discovery of 2,5-dimethoxy-4-thiotrifluoromethylphenethylamines, including CYB210010, a potent and long-acting serotonin 5-HT2 receptor agonist. CYB210010 exhibited high agonist potency at 5-HT2A and 5-HT2C receptors, modest selectivity over 5-HT2B, 5-HT1A, 5-HT6, and adrenergic α2A receptors, and lacked activity at monoamine transporters and over 70 other proteins. CYB210010 (0.1-3 mg/kg) elicited a head-twitch response (HTR) and could be administered subchronically at threshold doses without behavioral tolerance. CYB210010 was orally bioavailable in three species, readily and preferentially crossed into the CNS, engaged frontal cortex 5-HT2A receptors, and increased the expression of genes involved in neuroplasticity in the frontal cortex. CYB210010 represents a new tool molecule for investigating the therapeutic potential of 5-HT2 receptor activation. In addition, several other compounds with high 5-HT2A receptor potency, yet with little or no HTR activity, were discovered, providing the groundwork for the development of nonpsychedelic 5-HT2A receptor ligands.
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Affiliation(s)
- Geoffrey B Varty
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
| | - Clinton E Canal
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
- College of Pharmacy, Department of Pharmaceutical Sciences, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Tina A Mueller
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
- BioIVT, Hicksville, New York 11803, United States
| | - Joshua A Hartsel
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
- Consultant, UPS PO Box #105-650, 25422 Trabuco Road, Lake Forest, California 92630, United States
| | - Richa Tyagi
- College of Pharmacy, Department of Pharmaceutical Sciences, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Ken Avery
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
| | - Michael E Morgan
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
| | - Amy C Reichelt
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
- Faculty of Biomedicine, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Pradip Pathare
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
| | - Erik Stang
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
| | | | - Alex Nivorozhkin
- Cybin IRL Limited, North Wall Quay, 1 Spencer Dock, Dublin 1 DO1 X9R7, Ireland
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2
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Saraf TS, Chen Y, Tyagi R, Canal CE. Altered brain serotonin 5-HT 1A receptor expression and function in juvenile Fmr1 knockout mice. Neuropharmacology 2024; 245:109774. [PMID: 37923121 DOI: 10.1016/j.neuropharm.2023.109774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 10/01/2023] [Accepted: 10/21/2023] [Indexed: 11/07/2023]
Abstract
There are no approved pharmacotherapies for fragile X syndrome (FXS), a rare neurodevelopmental disorder caused by a mutation in the FMR1 promoter region that leads to various symptoms, including intellectual disability and auditory hypersensitivity. The gene that encodes inhibitory serotonin 1A receptors (5-HT1ARs) is differentially expressed in embryonic brain tissue from individuals with FXS, and 5-HT1ARs are highly expressed in neural systems that are disordered in FXS, providing a rationale to focus on 5-HT1ARs as targets to treat symptoms of FXS. We examined agonist-labeled 5-HT1AR densities in male and female Fmr1 knockout mice and found no differences in whole-brain 5-HT1AR expression in adult control compared to Fmr1 knockout mice. However, juvenile Fmr1 knockout mice had lower whole-brain 5-HT1AR expression than age-matched controls. Consistent with these results, juvenile Fmr1 knockout mice showed reduced behavioral responses elicited by the 5-HT1AR agonist (R)-8-OH-DPAT, effects blocked by the selective 5-HT1AR antagonist, WAY-100635. Also, treatment with the selective 5-HT1AR agonist, NLX-112, dose-dependently prevented audiogenic seizures (AGS) in juvenile Fmr1 knockout mice, an effect reversed by WAY-100635. Suggestive of a potential role for 5-HT1ARs in regulating AGS, compared to males, female Fmr1 knockout mice had a lower prevalence of AGS and higher expression of antagonist-labeled 5-HT1ARs in the inferior colliculus and auditory cortex. These results provide preclinical support that 5-HT1AR agonists may be therapeutic for young individuals with FXS hypersensitive to auditory stimuli.
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Affiliation(s)
- Tanishka S Saraf
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA, 30341, USA
| | - Yiming Chen
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA, 30341, USA
| | - Richa Tyagi
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA, 30341, USA
| | - Clinton E Canal
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA, 30341, USA.
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3
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Tyagi R, Saraf TS, Canal CE. The Psychedelic N, N-Dipropyltryptamine Prevents Seizures in a Mouse Model of Fragile X Syndrome via a Mechanism that Appears Independent of Serotonin and Sigma1 Receptors. ACS Pharmacol Transl Sci 2023; 6:1480-1491. [PMID: 37854624 PMCID: PMC10580393 DOI: 10.1021/acsptsci.3c00137] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Indexed: 10/20/2023]
Abstract
The serotonergic psychedelic psilocybin shows efficacy in treating neuropsychiatric disorders, though the mechanism(s) underlying its therapeutic effects remain unclear. We show that a similar psychedelic tryptamine, N,N-dipropyltryptamine (DPT), completely prevents audiogenic seizures (AGS) in an Fmr1 knockout mouse model of fragile X syndrome at a 10 mg/kg dose but not at lower doses (3 or 5.6 mg/kg). Despite showing in vitro that DPT is a serotonin 5-HT2A, 5-HT1B, and 5-HT1A receptor agonist (with that rank order of functional potency, determined with TRUPATH Gα/βγ biosensors), pretreatment with selective inhibitors of 5-HT2A/2C, 5-HT1B, or 5-HT1A receptors did not block DPT's antiepileptic effects; a pan-serotonin receptor antagonist was also ineffective. Because 5-HT1A receptor activation blocks AGS in Fmr1 knockout mice, we performed a dose-response experiment to evaluate DPT's engagement of 5-HT1A receptors in vivo. DPT elicited 5-HT1A-dependent effects only at doses greater than 10 mg/kg, further supporting that DPT's antiepileptic effects were not 5-HT1A-mediated. We also observed that the selective sigma1 receptor antagonist, NE-100, did not impact DPT's antiepileptic effects, suggesting DPT engagement of sigma1 receptors was not a crucial mechanism. Separately, we observed that DPT and NE-100 at high doses caused convulsions on their own that were qualitatively distinct from AGS. In conclusion, DPT dose-dependently blocked AGS in Fmr1 knockout mice, but neither serotonin nor sigma1 receptor antagonists prevented this action. Thus, DPT might have neurotherapeutic effects independent of its serotonergic psychedelic properties. However, DPT also caused seizures at high doses, showing that DPT has complex dose-dependent in vivo polypharmacology.
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Affiliation(s)
- Richa Tyagi
- Department of Pharmaceutical
Sciences, College of Pharmacy, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Tanishka S. Saraf
- Department of Pharmaceutical
Sciences, College of Pharmacy, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Clinton E. Canal
- Department of Pharmaceutical
Sciences, College of Pharmacy, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
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4
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Saraf TS, McGlynn RP, Bhatavdekar OM, Booth RG, Canal CE. FPT, a 2-Aminotetralin, Is a Potent Serotonin 5-HT 1A, 5-HT 1B, and 5-HT 1D Receptor Agonist That Modulates Cortical Electroencephalogram Activity in Adult Fmr1 Knockout Mice. ACS Chem Neurosci 2022; 13:3629-3640. [PMID: 36473166 PMCID: PMC10364582 DOI: 10.1021/acschemneuro.2c00574] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
There are no approved medicines for fragile X syndrome (FXS), a monogenic, neurodevelopmental disorder. Electroencephalogram (EEG) studies show alterations in resting-state cortical EEG spectra, such as increased gamma-band power, in patients with FXS that are also observed in Fmr1 knockout models of FXS, offering putative biomarkers for drug discovery. Genes encoding serotonin receptors (5-HTRs), including 5-HT1A, 5-HT1B, and 5-HT1DRs, are differentially expressed in FXS, providing a rationale for investigating them as pharmacotherapeutic targets. Previously we reported pharmacological activity and preclinical neurotherapeutic effects in Fmr1 knockout mice of an orally active 2-aminotetralin, (S)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (FPT). FPT is a potent (low nM), high-efficacy partial agonist at 5-HT1ARs and a potent, low-efficacy partial agonist at 5-HT7Rs. Here we report new observations that FPT also has potent and efficacious agonist activity at human 5-HT1B and 5-HT1DRs. FPT's Ki values at 5-HT1B and 5-HT1DRs were <5 nM, but it had nil activity (>10 μM Ki) at 5-HT1FRs. We tested the effects of FPT (5.6 mg/kg, subcutaneous) on EEG recorded above the somatosensory and auditory cortices in freely moving, adult Fmr1 knockout and control mice. Consistent with previous reports, we observed significantly increased relative gamma power in untreated or vehicle-treated male and female Fmr1 knockout mice from recordings above the left somatosensory cortex (LSSC). In addition, we observed sex effects on EEG power. FPT did not eliminate the genotype difference in relative gamma power from the LSSC. FPT, however, robustly decreased relative alpha power in the LSSC and auditory cortex, with more pronounced effects in Fmr1 KO mice. Similarly, FPT decreased relative alpha power in the right SSC but only in Fmr1 knockout mice. FPT also increased relative delta power, with more pronounced effects in Fmr1 KO mice and caused small but significant increases in relative beta power. Distinct impacts of FPT on cortical EEG were like effects caused by certain FDA-approved psychotropic medications (including baclofen, allopregnanolone, and clozapine). These results advance the understanding of FPT's pharmacological and neurophysiological effects.
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Affiliation(s)
- Tanishka S Saraf
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Ryan P McGlynn
- Center for Drug Discovery, Department of Pharmaceutical Sciences, and Department of Chemistry and Chemical Biology, Northeastern University, 300 Huntington Street, Boston, Massachusetts 02115, United States
| | - Omkar M Bhatavdekar
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, 3400 North Charles Street, Croft Hall B27, Baltimore, Maryland 21218, United States
| | - Raymond G Booth
- Center for Drug Discovery, Department of Pharmaceutical Sciences, and Department of Chemistry and Chemical Biology, Northeastern University, 300 Huntington Street, Boston, Massachusetts 02115, United States
| | - Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
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5
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Saraf TS, Yang B, McGlynn RP, Booth RG, Canal CE. Targeting 5‐HT1A Receptors to Correct Neuronal Hyperexcitability in Fmr1 Knockout Mice. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r4662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Tanishka S. Saraf
- Pharmaceutical ScienceMercer University College of PharmacyAtlantaGA
| | - Bo Yang
- Georgia Institute of TechnologyAtlantaGA
| | | | | | - Clinton E. Canal
- Pharmaceutical ScienceMercer University College of PharmacyAtlantaGA
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6
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Armstrong JL, Canal CE. Targeting 5‐HT
1A
Receptors to Correct Perineuronal Net and Social Behavioral Deficits in
Fmr1
Knockout Mice, a Model of Fragile X Syndrome. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r2453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Armstrong JL, Saraf TS, Bhatavdekar O, Canal CE. Spontaneous seizures in adult Fmr1 knockout mice: FVB.129P2-Pde6b+ Tyr Fmr1/J. Epilepsy Res 2022; 182:106891. [PMID: 35290907 PMCID: PMC9050957 DOI: 10.1016/j.eplepsyres.2022.106891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 01/26/2023]
Abstract
The prevalence of seizures in individuals with fragile X syndrome (FXS) is ~25%; however, there are no reports of spontaneous seizures in the Fmr1 knockout mouse model of FXS. Herein, we report that 48% of adult (median age P96), Fmr1 knockout mice from our colony were found expired in their home cages. We observed and recorded adult Fmr1 knockout mice having spontaneous convulsions in their home cages. In addition, we captured by electroencephalography an adult Fmr1 knockout mouse having a spontaneous seizure-during preictal, ictal, and postictal phases-which confirmed the presence of a generalized seizure. We did not observe this phenotype in control conspecifics or in juvenile (age <P35) Fmr1 knockout mice. We hypothesized that chronic, random, noise perturbations during development caused the phenotype. We recorded decibels (dB) in our vivarium. The average was 61 dB, but operating the automatic door to the vivarium caused spikes to 95 dB. We modified the door to eliminate noise spikes, which reduced unexpected deaths to 33% in Fmr1 knockout mice raised from birth in this environment (P = 0.07). As the modifications did not eliminate unexpected deaths, we further hypothesized that building vibrations may also be a contributing factor. After installing anti-vibration pads underneath housing carts, unexpected deaths of Fmr1 knockout mice born and raised in this environment decreased to 29% (P < 0.01 compared to the original environment). We also observed significant sex effects, for example, after interventions to reduce sound and vibration, significantly fewer male, but not female, Fmr1 knockout mice died unexpectedly (P < 0.001). The spontaneous seizure phenotype in our Fmr1 knockout mice could serve as a model of seizures observed in individuals with FXS, potentially offering a new translationally-valid phenotype for FXS research. Finally, these observations, although anomalous, serve as a reminder to consider gene-environment interactions when interpreting data derived from Fmr1 knockout mice.
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Affiliation(s)
- Jessica L Armstrong
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA 30341, USA
| | - Tanishka S Saraf
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA 30341, USA
| | - Omkar Bhatavdekar
- Johns Hopkins University, Department of Chemical and Biomolecular Engineering, 3400 North Charles Street, Croft Hall B27, Baltimore, MD 21218, USA
| | - Clinton E Canal
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA 30341, USA.
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8
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Casey AB, Cui M, Booth RG, Canal CE. "Selective" serotonin 5-HT 2A receptor antagonists. Biochem Pharmacol 2022; 200:115028. [PMID: 35381208 DOI: 10.1016/j.bcp.2022.115028] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 01/29/2023]
Abstract
Blockade of the serotonin 5-HT2A G protein-coupled receptor (5-HT2AR) is a fundamental pharmacological characteristic of numerous antipsychotic medications, which are FDA-approved to treat schizophrenia, bipolar disorder, and as adjunctive therapies in major depressive disorder. Meanwhile, activation of the 5-HT2AR by serotonergic psychedelics may be useful in treating neuropsychiatric indications, including major depressive and substance use disorders. Serotonergic psychedelics and other 5-HT2AR agonists, however, often bind other receptors, and standard 5-HT2AR antagonists lack sufficient selectivity to make well-founded mechanistic conclusions about the 5-HT2AR-dependent effects of these compounds and the general neurobiological function of 5-HT2ARs. This review discusses the limitations and strengths of currently available "selective" 5-HT2AR antagonists, the molecular determinants of antagonist selectivity at 5-HT2ARs, and the utility of molecular pharmacological and computational methods in guiding the discovery of novel unambiguously selective 5-HT2AR antagonists.
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Affiliation(s)
- Austen B Casey
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Boston, Massachusetts 02115, USA; Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115, USA
| | - Raymond G Booth
- Department of Pharmaceutical Sciences, Boston, Massachusetts 02115, USA; Department of Chemistry and Chemical Biology, Boston, Massachusetts 02115, USA; Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115, USA
| | - Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University Health Sciences Center, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, USA
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9
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Canal CE, Leopoldo M. The Need To Improve Reporting of the Pharmacological Action of New Molecules. ACS Chem Neurosci 2022; 13:185-186. [PMID: 34989567 DOI: 10.1021/acschemneuro.1c00829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The molecular characterization of bioactive molecules, for example, small molecules targeting G-protein-coupled receptors, is evolving in complexity, impacting the meaning of terms like "agonist", "antagonist", and "selective", which, in the absence of detailed definitions and scientific consensus, can be sources of confusion in the literature. We discuss this issue and offer straightforward solutions to it.
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Affiliation(s)
- Clinton E. Canal
- College of Pharmacy, Department of Pharmaceutical Sciences, Mercer University, Atlanta, Georgia 30341, United States
| | - Marcello Leopoldo
- Dipartimento di Farmacia, Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy
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10
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León F, Obeng S, Mottinelli M, Chen Y, King TI, Berthold EC, Kamble SH, Restrepo LF, Patel A, Gamez-Jimenez LR, Lopera-Londoño C, Hiranita T, Sharma A, Hampson AJ, Canal CE, McMahon LR, McCurdy CR. Activity of Mitragyna speciosa ("Kratom") Alkaloids at Serotonin Receptors. J Med Chem 2021; 64:13510-13523. [PMID: 34467758 PMCID: PMC9235362 DOI: 10.1021/acs.jmedchem.1c00726] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Kratom alkaloids have mostly been evaluated for their opioid activity but less at other targets that could contribute to their physiological effects. Here, we investigated the in vitro and in vivo activity of kratom alkaloids at serotonin receptors (5-HTRs). Paynantheine and speciogynine exhibited high affinity for 5-HT1ARs and 5-HT2BRs, unlike the principal kratom alkaloid mitragynine. Both alkaloids produced antinociceptive properties in rats via an opioid receptor-independent mechanism, and neither activated 5-HT2BRs in vitro. Paynantheine, speciogynine, and mitragynine induced lower lip retraction and antinociception in rats, effects blocked by a selective 5-HT1AR antagonist. In vitro functional assays revealed that the in vivo 5-HT1AR agonistic effects may be due to the metabolites 9-O-desmethylspeciogynine and 9-O-desmethylpaynantheine and not the parent compounds. Both metabolites did not activate 5-HT2BR, suggesting low inherent risk of causing valvulopathy. The 5-HT1AR agonism by kratom alkaloids may contribute to the mood-enhancing effects associated with kratom use.
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Affiliation(s)
- Francisco León
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Samuel Obeng
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Marco Mottinelli
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Yiming Chen
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, Georgia 30341, United States
| | - Tamara I King
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, Florida 32610, United States
| | - Erin C Berthold
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, Florida 32610, United States
| | - Shyam H Kamble
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, Florida 32610, United States
| | - Luis F Restrepo
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Avi Patel
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Lea R Gamez-Jimenez
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Carolina Lopera-Londoño
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Takato Hiranita
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Abhisheak Sharma
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, Florida 32610, United States
| | - Aidan J Hampson
- Division of Therapeutics and Medical Consequences, National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, Georgia 30341, United States
| | - Lance R McMahon
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Christopher R McCurdy
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, Florida 32610, United States
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11
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Lindsley CW, Canal CE. NeuroChat with Professor Clinton E. Canal. ACS Chem Neurosci 2020; 11:3485-3487. [PMID: 33143427 DOI: 10.1021/acschemneuro.0c00565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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12
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Armstrong JL, Chen Y, Saraf TS, Canal CE. Sex Differences in an
Fmr1
Knock‐out Mouse Model of Fragile X Syndrome. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Chen Y, Canal CE. Structure Activity Relationship Studies of Psychostimulant Synthetic Cathinones Reveal Nanomolar Antagonist Potency of α‐Pyrrolidinohexiophenone (α‐PHP) at Human Muscarinic M
2
Receptors. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Saraf TS, Chen Y, Canal CE. Exploring 5‐HT
2
Receptors as Targets for Treating Epilepsy in Fragile X Syndrome: A Preclinical Study of
Fmr1
Knock‐out Mice. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Chen Y, Canal CE. Structure-Activity Relationship Study of Psychostimulant Synthetic Cathinones Reveals Nanomolar Antagonist Potency of α-Pyrrolidinohexiophenone at Human Muscarinic M 2 Receptors. ACS Chem Neurosci 2020; 11:960-968. [PMID: 32073252 DOI: 10.1021/acschemneuro.0c00008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Synthetic cathinones (SCs) are designer, psychostimulant drugs of abuse that primarily act on monoamine transporters; little is known about their off-target liability. Abuse of pyrrolidine-containing SCs, such as α-PHP, has been linked to clinical features, including tachycardia and hypertension, and psychiatric events, including delusions and memory impairments-effects mimicking deliriant hallucinogens that are acetylcholine muscarinic receptor (MR) antagonists. α-PHP and nine analogs with modifications in the α-carbon side chain length and/or containing a methylenedioxy moiety were screened for activity at each of the five human MRs. Increasing the length of the α-carbon side chain of 1-phenyl-2-(pyrrolidin-1-yl)ethan-1-one analogs from a methyl (α-PPP) to a propyl (α-PVP) group caused a steep increase in affinity at all MR subtypes, and one extra carbon (α-PHP) further enhanced MR affinity; the presence of a methylenedioxy moiety generally hindered this effect. Highest MR affinity was observed with α-PHP at M2Rs-its M2R affinity (Ki = 251 nM) was 302-fold higher than α-PPP's. M2R-cAMP inhibition and β-arrestin recruitment assays showed that α-PHP is an M2R antagonist (Kb = 120 and 502 nM, respectively). Additional experiments showed α-PHP is also an antagonist of M1R-inositol phosphate production (Kb = 1.4 μM). Human toxicology studies report blood concentrations of pyrrolidine-containing SCs, including α-PHP, that reach micromolar levels during intoxication, indicating α-PHP's MR activity might have physiological relevance. As M2Rs and M1Rs are widely expressed in the autonomic and central nervous systems, α-PHP's anticholinergic activity might be relevant to adverse events associated with α-PHP intoxication.
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Affiliation(s)
- Yiming Chen
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Clinton E. Canal
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
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Armstrong JL, Casey AB, Saraf TS, Mukherjee M, Booth RG, Canal CE. ( S)-5-(2'-Fluorophenyl)- N, N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine, a Serotonin Receptor Modulator, Possesses Anticonvulsant, Prosocial, and Anxiolytic-like Properties in an Fmr1 Knockout Mouse Model of Fragile X Syndrome and Autism Spectrum Disorder. ACS Pharmacol Transl Sci 2020; 3:509-523. [PMID: 32566916 DOI: 10.1021/acsptsci.9b00101] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Indexed: 12/12/2022]
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder characterized by intellectual disabilities and a plethora of neuropsychiatric symptoms. FXS is the leading monogenic cause of autism spectrum disorder (ASD), which is defined clinically by repetitive and/or restrictive patterns of behavior and social communication deficits. Epilepsy and anxiety are also common in FXS and ASD. Serotonergic neurons directly innervate and modulate the activity of neurobiological circuits altered in both disorders, providing a rationale for investigating serotonin receptors (5-HTRs) as targets for FXS and ASD drug discovery. Previously we unveiled an orally active aminotetralin, (S)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (FPT), that exhibits partial agonist activity at 5-HT1ARs, 5-HT2CRs, and 5-HT7Rs and that reduces repetitive behaviors and increases social approach behavior in wild-type mice. Here we report that in an Fmr1 knockout mouse model of FXS and ASD, FPT is prophylactic for audiogenic seizures. No FPT-treated mice displayed audiogenic seizures, compared to 73% of vehicle-treated mice. FPT also exhibits anxiolytic-like effects in several assays and increases social interactions in both Fmr1 knockout and wild-type mice. Furthermore, FPT increases c-Fos expression in the basolateral amygdala, which is a preclinical effect produced by anxiolytic medications. Receptor pharmacology assays show that FPT binds competitively and possesses rapid association and dissociation kinetics at 5-HT1ARs and 5-HT7Rs, yet has slow association and rapid dissociation kinetics at 5-HT2CRs. Finally, we reassessed and report FPT's affinity and function at 5-HT1ARs, 5-HT2CRs, and 5-HT7Rs. Collectively, these observations provide mounting support for further development of FPT as a pharmacotherapy for common neuropsychiatric symptoms in FXS and ASD.
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Affiliation(s)
- Jessica L Armstrong
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University Health Sciences Center, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Austen B Casey
- Center for Drug Discovery, Department of Pharmaceutical Sciences, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02131, United States
| | - Tanishka S Saraf
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University Health Sciences Center, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
| | - Munmun Mukherjee
- Center for Drug Discovery, Department of Pharmaceutical Sciences, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02131, United States
| | - Raymond G Booth
- Center for Drug Discovery, Department of Pharmaceutical Sciences, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02131, United States
| | - Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University Health Sciences Center, Mercer University, 3001 Mercer University Drive, Atlanta, Georgia 30341, United States
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17
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Perry CK, Casey AB, Felsing DE, Vemula R, Zaka M, Herrington NB, Cui M, Kellogg GE, Canal CE, Booth RG. Synthesis of novel 5-substituted-2-aminotetralin analogs: 5-HT1A and 5-HT7 G protein-coupled receptor affinity, 3D-QSAR and molecular modeling. Bioorg Med Chem 2020; 28:115262. [DOI: 10.1016/j.bmc.2019.115262] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/21/2019] [Accepted: 12/09/2019] [Indexed: 11/30/2022]
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18
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 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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Abstract
Recent, well-controlled - albeit small-scale - clinical trials show that serotonergic psychedelics, including psilocybin and lysergic acid diethylamide, possess great promise for treating psychiatric disorders, including treatment-resistant depression. Additionally, fresh results from a deluge of clinical neuroimaging studies are unveiling the dynamic effects of serotonergic psychedelics on functional activity within, and connectivity across, discrete neural systems. These observations have led to testable hypotheses regarding neural processing mechanisms that contribute to psychedelic effects and therapeutic benefits. Despite these advances and a plethora of preclinical and clinical observations supporting a central role for brain serotonin 5-HT2A receptors in producing serotonergic psychedelic effects, lingering and new questions about mechanisms abound. These chiefly pertain to molecular neuropharmacology. This chapter is devoted to illuminating and discussing such questions in the context of preclinical experimental approaches for studying mechanisms of action of serotonergic psychedelics, classic and new.
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Affiliation(s)
- Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, GA, USA.
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20
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Chen Y, Blough BE, Murnane KS, Canal CE. The synthetic cathinone psychostimulant α-PPP antagonizes serotonin 5-HT 2A receptors: In vitro and in vivo evidence. Drug Test Anal 2019; 11:990-998. [PMID: 30845376 DOI: 10.1002/dta.2582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 01/08/2023]
Abstract
Synthetic cathinones (SCs) are β-keto analogs of amphetamines. Like amphetamines, SCs target monoamine transporters; however, unusual neuropsychiatric symptoms have been associated with abuse of some SCs, suggesting SCs might possess additional pharmacological properties. We performed radioligand competition binding assays to assess the affinities of nine SCs at human 5-HT2A receptors (5-HT2A R) and muscarinic M1 receptors (M1 R) transiently expressed in HEK293 cells. None of the SCs exhibited affinity at M1 R (minimal displacement of [~Kd ] [3 H]scopolamine up to 10 μM). However, two SCs, α-pyrrolidinopropiophenone (α-PPP) and 4-methyl-α-PPP, had low μM Ki values at 5-HT2A R. In 5-HT2A R-phosphoinositide hydrolysis assays, α-PPP and 4-methyl-α-PPP displayed inverse agonist activity. We further assessed the 5-HT2A R functional activity of α-PPP, and observed it competitively antagonized 5-HT2A R signaling stimulated by the 5-HT2 R agonist (±)-2,5-dimethoxy-4-iodoamphetamine (DOI; Kb = 851 nM). To assess in vivo 5-HT2A R activity, we examined the effects of α-PPP on the DOI-elicited head-twitch response (HTR) in mice. α-PPP dose-dependently blocked the HTR with maximal suppression at 10 mg/kg (P < 0.0001), which is a moderate dose used in studies investigating psychostimulant properties of α-PPP. To corroborate a 5-HT2A R mechanism, we also tested 3,4-methylenedioxy-α-PPP (MDPPP) and 3-bromomethcathinone (3-BMC), SCs that we observed had 5-HT2A R Ki s > 10 μM. Neither MDPPP nor 3-BMC, at 10 mg/kg doses, attenuated the DOI HTR. Our results suggest α-PPP has antagonist interactions at 5-HT2A R in vitro that may translate at physiologically-relevant doses in vivo. Considering 5-HT2A R antagonism has been shown to mitigate effects of psychostimulants, this property may contribute to α-PPPs unpopularity compared to other monoamine transporter inhibitors.
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Affiliation(s)
- Yiming Chen
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, GA, USA
| | - Bruce E Blough
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, USA
| | - Kevin S Murnane
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, GA, USA
| | - Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, GA, USA
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Felsing DE, Canal CE, Booth RG. Ligand-directed serotonin 5-HT 2C receptor desensitization and sensitization. Eur J Pharmacol 2019; 848:131-139. [PMID: 30689993 DOI: 10.1016/j.ejphar.2019.01.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/31/2022]
Abstract
Exposure of G protein-coupled receptors (GPCRs) to agonists can desensitize receptor signaling and lead to drug tolerance, whereas inverse agonists can sensitize signaling. For example, activation of serotonin 5-HT2C GPCRs is pharmacotherapeutic for obesity, but there is tolerance to the anorectic effect of the only approved 5-HT2C agonist, lorcaserin. We tested the hypothesis that different agonists or inverse agonists differentially desensitize or sensitize, respectively, canonical 5-HT2C-mediated activation of phospholipase C (PLC) signaling in vitro. Lorcaserin, which displays potency and efficacy equal to 5-HT, desensitized the 5-HT2C receptor significantly more than 5-HT (p<0.05). Agonist chemotypes such as 2-aminotetralins, with similar potency but lower efficacy than 5-HT, produced little 5-HT2C desensitization. The piperazine agonist 1-(3-chlorophenyl)piperazine (mCPP), with lower potency but similar efficacy as 5-HT, elicited desensitization indistinguishable from 5-HT, while the piperazine agonist aripiprazole, with lower potency and efficacy, did not desensitize 5-HT2C-PLC signaling. Several 5-HT2C agonists also were assessed for β-arrestin recruitment-lorcaserin was a 'super-agonist', but a 2-aminotetralin and aripiprazole had nil activity, suggesting they are biased towards 5-HT2C-PLC signaling. We observed robust positive correlations between the magnitude of 5-HT2C desensitization and agonist efficacy to stimulate PLC or to recruit β-arrestin. In contrast, different inverse agonists caused different magnitudes of 5-HT2C sensitization that did not correlate with efficacy (or potency) to inhibit constitutive 5-HT2C-PLC signaling. Assessment of the 5-HT2C-S407A point-mutated receptor indicated this residue's involvement in ligand-dependent desensitization, but we did not observe a role for protein kinase C.These data show that ligand structure uniquely impacts 5-HT2C desensitization and sensitization processes..
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Affiliation(s)
- Daniel E Felsing
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, United States.
| | - Clinton E Canal
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States.
| | - Raymond G Booth
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, United States; Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, United States.
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22
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Abstract
Aripiprazole was the first antipsychotic developed to possess agonist properties at dopamine D2 autoreceptors, a groundbreaking strategy that presented a new vista for schizophrenia drug discovery. The dopamine D2 receptor is the crucial target of all extant antipsychotics, and all developed prior to aripiprazole were D2 receptor antagonists. Extensive blockade of these receptors, however, typically produces extrapyramidal (movement) side effects, which plagued first-generation antipsychotics, such as haloperidol. Second-generation antipsychotics, such as clozapine, with unique polypharmacology and D2 receptor binding kinetics, have significantly lower risk of movement side effects but can cause myriad additional ones, such as severe weight gain and metabolic dysfunction. Aripiprazole's polypharmacology, characterized by its unique agonist activity at dopamine D2 and D3 and serotonin 5-HT1A receptors, as well as antagonist activity at serotonin 5-HT2A receptors, translates to successful reduction of positive, negative, and cognitive symptoms of schizophrenia, while also mitigating risk of weight gain and movement side effects. New observations, however, link aripiprazole to compulsive behaviors in a small group of patients, an unusual side effect for antipsychotics. In this review, we discuss the chemical synthesis, pharmacology, pharmacogenomics, drug metabolism, and adverse events of aripiprazole, and we present a current understanding of aripiprazole's neurotherapeutic mechanisms, as well as the history and importance of aripiprazole to neuroscience.
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Affiliation(s)
- Austen B. Casey
- Department of Pharmaceutical Sciences, Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115, United States
| | - Clinton E. Canal
- Department of Pharmaceutical Sciences, Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115, United States
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23
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Liu Y, Canal CE, Cordova-Sintjago TC, Zhu W, Booth RG. Mutagenesis Analysis Reveals Distinct Amino Acids of the Human Serotonin 5-HT 2C Receptor Underlying the Pharmacology of Distinct Ligands. ACS Chem Neurosci 2017; 8:28-39. [PMID: 27580242 DOI: 10.1021/acschemneuro.6b00124] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
While exploring the structure-activity relationship of 4-phenyl-2-dimethylaminotetralins (PATs) at serotonin 5-HT2C receptors, we discovered that relatively minor modification of PAT chemistry impacts function at 5-HT2C receptors. In HEK293 cells expressing human 5-HT2C-INI receptors, for example, (-)-trans-3'-Br-PAT and (-)-trans-3'-Cl-PAT are agonists regarding Gαq-inositol phosphate signaling, whereas (-)-trans-3'-CF3-PAT is an inverse agonist. To investigate the ligand-receptor interactions that govern this change in function, we performed site-directed mutagenesis of 14 amino acids of the 5-HT2C receptor based on molecular modeling and reported G protein-coupled receptor crystal structures, followed by molecular pharmacology studies. We found that S3.36, T3.37, and F5.47 in the orthosteric binding pocket are critical for affinity (Ki) of all PATs tested, we also found that F6.44, M6.47, C7.45, and S7.46 are primarily involved in regulating EC/IC50 functional potencies of PATs. We discovered that when residue S5.43, N6.55, or both are mutated to alanine, (-)-trans-3'-CF3-PAT switches from inverse agonist to agonist function, and when N6.55 is mutated to leucine, (-)-trans-3'-Br-PAT switches from agonist to inverse agonist function. Notably, most point-mutations that affected PAT pharmacology did not significantly alter affinity (KD) of the antagonist radioligand [3H]mesulergine, but every mutation tested negatively impacted serotonin binding. Also, amino acid mutations differentially affected the pharmacology of other commercially available 5-HT2C ligands tested. Collectively, the data show that functional outcomes shared by different ligands are mediated by different amino acids and that some 5-HT2C receptor residues important for pharmacology of one ligand are not necessarily important for another ligand.
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Affiliation(s)
- Yue Liu
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, and Department
of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Clinton E. Canal
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, and Department
of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Tania C. Cordova-Sintjago
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, and Department
of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Medicinal Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Wanying Zhu
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, and Department
of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Raymond G. Booth
- Center
for Drug Discovery, Department of Pharmaceutical Sciences, and Department
of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Medicinal Chemistry, University of Florida, Gainesville, Florida 32611, United States
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Abstract
Classic hallucinogens share pharmacology as serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptor agonists. Unique among most other Schedule 1 drugs, they are generally non-addictive and can be effective tools in the treatment of addiction. Mechanisms underlying these attributes are largely unknown. However, many preclinical studies show that 5-HT2C agonists counteract the addictive effects of drugs from several classes, suggesting this pharmacological property of classic hallucinogens may be significant. Drawing from a comprehensive analysis of preclinical behavior, neuroanatomy, and neurochemistry studies, this review builds rationale for this hypothesis, and also proposes a testable, neurobiological framework. 5-HT2C agonists work, in part, by modulating dopamine neuron activity in the ventral tegmental area-nucleus accumbens (NAc) reward pathway. We argue that activation of 5-HT2C receptors on NAc shell, GABAergic, medium spiny neurons inhibits potassium Kv1.x channels, thereby enhancing inhibitory activity via intrinsic mechanisms. Together with experiments that show that addictive drugs, such as cocaine, potentiate Kv1.x channels, thereby suppressing NAc shell GABAergic activity, this hypothesis provides a mechanism by which classic hallucinogen-mediated stimulation of 5-HT2C receptors could thwart addiction. It also provides a potential reason for the non-addictive nature of classic hallucinogens.
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Affiliation(s)
- Clinton E Canal
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, USA
| | - Kevin S Murnane
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, Mercer University Health Sciences Center, Atlanta, USA
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Canal CE, Felsing DE, Liu Y, Zhu W, Wood JT, Perry CK, Vemula R, Booth RG. Correction to an orally active phenylaminotetralin-chemotype serotonin 5-HT7 and 5-HT1A receptor partial agonist that corrects motor stereotypy in mouse models. ACS Chem Neurosci 2015. [PMID: 26225542 DOI: 10.1021/acschemneuro.5b00197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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26
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Canal CE, Felsing DE, Liu Y, Zhu W, Wood JT, Perry CK, Vemula R, Booth RG. An Orally Active Phenylaminotetralin-Chemotype Serotonin 5-HT7 and 5-HT1A Receptor Partial Agonist that Corrects Motor Stereotypy in Mouse Models. ACS Chem Neurosci 2015; 6:1259-70. [PMID: 26011730 DOI: 10.1021/acschemneuro.5b00099] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Stereotypy (e.g., repetitive hand waving) is a key phenotype of autism spectrum disorder, Fragile X and Rett syndromes, and other neuropsychiatric disorders, and its severity correlates with cognitive and attention deficits. There are no effective treatments, however, for stereotypy. Perturbation of serotonin (5-HT) neurotransmission contributes to stereotypy, suggesting that distinct 5-HT receptors may be pharmacotherapeutic targets to treat stereotypy and related neuropsychiatric symptoms. For example, preclinical studies indicate that 5-HT7 receptor activation corrects deficits in mouse models of Fragile X and Rett syndromes, and clinical trials for autism are underway with buspirone, a 5-HT1A partial agonist with relevant affinity at 5-HT7 receptors. Herein, we report the synthesis, in vitro molecular pharmacology, behavioral pharmacology, and pharmacokinetic parameters in mice after subcutaneous and oral administration of (+)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine ((+)-5-FPT), a new, dual partial agonist targeting both 5-HT7 (Ki = 5.8 nM, EC50 = 34 nM) and 5-HT1A (Ki = 22 nM, EC50 = 40 nM) receptors. Three unique, heterogeneous mouse models were used to assess the efficacy of (+)-5-FPT to reduce stereotypy: idiopathic jumping in C58/J mice, repetitive body rotations in C57BL/6J mice treated with the NMDA antagonist, MK-801, and repetitive head twitching in C57BL/6J mice treated with the 5-HT2 agonist, DOI. Systemic (+)-5-FPT potently and efficaciously reduced or eliminated stereotypy in each of the mouse models without altering locomotor behavior on its own, and additional tests showed that (+)-5-FPT, at the highest behaviorally active dose tested, enhanced social interaction and did not cause behaviors indicative of serotonin syndrome. These data suggest that (+)-5-FPT is a promising medication for treating stereotypy in psychiatric disorders.
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Affiliation(s)
- Clinton E. Canal
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Daniel E. Felsing
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Yue Liu
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Wanying Zhu
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - JodiAnne T. Wood
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Charles K. Perry
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Rajender Vemula
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Raymond G. Booth
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
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27
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Sakhuja R, Kondabolu K, Córdova-Sintjago T, Travers S, Vincek AS, Kim MS, Abboud KA, Fang L, Sun Z, Canal CE, Booth RG. Novel 4-substituted-N,N-dimethyltetrahydronaphthalen-2-amines: synthesis, affinity, and in silico docking studies at serotonin 5-HT2-type and histamine H1 G protein-coupled receptors. Bioorg Med Chem 2015; 23:1588-600. [PMID: 25703249 PMCID: PMC4363177 DOI: 10.1016/j.bmc.2015.01.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/22/2015] [Accepted: 01/30/2015] [Indexed: 10/24/2022]
Abstract
Syntheses were undertaken of derivatives of (2S,4R)-(-)-trans-4-phenyl-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (4-phenyl-2-dimethylaminotetralin, PAT), a stereospecific agonist at the serotonin 5-HT2C G protein-coupled receptor (GPCR), with inverse agonist activity at 5-HT2A and 5-HT2B GPCRs. Molecular changes were made at the PAT C(4)-position, while preserving N,N-dimethyl substitution at the 2-position as well as trans-stereochemistry, structural features previously shown to be optimal for 5-HT2 binding. Affinities of analogs were determined at recombinant human 5-HT2 GPCRs in comparison to the phylogenetically closely-related histamine H1 GPCR, and in silico ligand docking studies were conducted at receptor molecular models to help interpret pharmacological results and guide future ligand design. In most cases, C(4)-substituted PAT analogs exhibited the same stereoselectivity ([-]-trans>[+]-trans) as the parent PAT across 5-HT2 and H1 GPCRs, albeit, with variable receptor selectivity. 4-(4'-substituted)-PAT analogs, however, demonstrated reversed stereoselectivity ([2S,4R]-[+]-trans>[2S,4R]-[-]-trans), with absolute configuration confirmed by single X-ray crystallographic data for the 4-(4'-Cl)-PAT analog. Pharmacological affinity results and computational results herein support further PAT drug development studies and provide a basis for predicting and interpreting translational results, including, for (+)-trans-4-(4'-Cl)-PAT and (-)-trans-4-(3'-Br)-PAT that were previously shown to be more potent and efficacious than their corresponding enantiomers in rodent models of psychoses, psychostimulant-induced behaviors, and compulsive feeding ('binge-eating').
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MESH Headings
- Binding Sites
- Binding, Competitive/physiology
- Computer Simulation
- Crystallography, X-Ray
- Humans
- Naphthalenes/chemical synthesis
- Naphthalenes/metabolism
- Protein Structure, Secondary
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Histamine H1/chemistry
- Receptors, Histamine H1/metabolism
- Receptors, Serotonin, 5-HT2/chemistry
- Receptors, Serotonin, 5-HT2/metabolism
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Affiliation(s)
- Rajeev Sakhuja
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Krishnakanth Kondabolu
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Tania Córdova-Sintjago
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States; Center for Drug Discovery, Department of Pharmaceutical Sciences and Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115-5000, United States
| | - Sean Travers
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Adam S Vincek
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Myong Sang Kim
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Khalil A Abboud
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Lijuan Fang
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Zhuming Sun
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Clinton E Canal
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States; Center for Drug Discovery, Department of Pharmaceutical Sciences and Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115-5000, United States
| | - Raymond G Booth
- Department of Medicinal Chemistry and Department of Chemistry, University of Florida, Gainesville, FL 32610-0485, United States; Center for Drug Discovery, Department of Pharmaceutical Sciences and Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115-5000, United States.
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Canal CE, Morgan D, Felsing D, Kondabolu K, Rowland NE, Robertson KL, Sakhuja R, Booth RG. A novel aminotetralin-type serotonin (5-HT) 2C receptor-specific agonist and 5-HT2A competitive antagonist/5-HT2B inverse agonist with preclinical efficacy for psychoses. J Pharmacol Exp Ther 2014; 349:310-8. [PMID: 24563531 DOI: 10.1124/jpet.113.212373] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Development of 5-HT2C agonists for treatment of neuropsychiatric disorders, including psychoses, substance abuse, and obesity, has been fraught with difficulties, because the vast majority of reported 5-HT2C selective agonists also activate 5-HT2A and/or 5-HT2B receptors, potentially causing hallucinations and/or cardiac valvulopathy. Herein is described a novel, potent, and efficacious human 5-HT2C receptor agonist, (-)-trans-(2S,4R)-4-(3'[meta]-bromophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (-)-MBP), that is a competitive antagonist and inverse agonist at human 5-HT2A and 5-HT2B receptors, respectively. (-)-MBP has efficacy comparable to the prototypical second-generation antipsychotic drug clozapine in three C57Bl/6 mouse models of drug-induced psychoses: the head-twitch response elicited by [2,5]-dimethoxy-4-iodoamphetamine; hyperlocomotion induced by MK-801 [(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (dizocilpine maleate)]; and hyperlocomotion induced by amphetamine. (-)-MBP, however, does not alter locomotion when administered alone, distinguishing it from clozapine, which suppresses locomotion. Finally, consumption of highly palatable food by mice was not increased by (-)-MBP at a dose that produced at least 50% maximal efficacy in the psychoses models. Compared with (-)-MBP, the enantiomer (+)-MBP was much less active across in vitro affinity and functional assays using mouse and human receptors and also translated in vivo with comparably lower potency and efficacy. Results indicate a 5-HT2C receptor-specific agonist, such as (-)-MBP, may be pharmacotherapeutic for psychoses, without liability for obesity, hallucinations, heart disease, sedation, or motoric disorders.
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Affiliation(s)
- Clinton E Canal
- Center for Drug Discovery (C.E.C., R.G.B.), Department of Pharmaceutical Sciences (C.E.C., R.G.B.), and Department of Chemistry and Chemical Biology (R.G.B.), Northeastern University, Boston, Massachusetts; Department of Psychiatry (D.M.), Medicinal Chemistry (D.F., R.S., K.K., R.G.B.), and Psychology (N.E.R., K.L.R.), University of Florida, Gainesville, Florida
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Canal CE, Cordova-Sintjago T, Liu Y, Kim MS, Morgan D, Booth RG. Molecular pharmacology and ligand docking studies reveal a single amino acid difference between mouse and human serotonin 5-HT2A receptors that impacts behavioral translation of novel 4-phenyl-2-dimethylaminotetralin ligands. J Pharmacol Exp Ther 2013; 347:705-16. [PMID: 24080681 DOI: 10.1124/jpet.113.208637] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
During translational studies to develop 4-phenyl-2-dimethylaminotetralin (PAT) compounds for neuropsychiatric disorders, the (2R,4S)-trans-(+)- and (2S,4R)-trans-(-)-enantiomers of the analog 6-hydroxy-7-chloro-PAT (6-OH-7-Cl-PAT) demonstrated unusual pharmacology at serotonin (5-HT) 5-HT2 G protein-coupled receptors (GPCRs). The enantiomers had similar affinities (Ki) at human (h) 5-HT2A receptors (≈ 70 nM). In an in vivo mouse model of 5-HT2A receptor activation [(±)-(2,5)-dimethoxy-4-iodoamphetamine (DOI)-elicited head twitch], however, (-)-6-OH-7-Cl-PAT was about 5-fold more potent than the (+)-enantiomer at attenuating the DOI-elicited response. It was discovered that (+)-6-OH-7-Cl-PAT (only) had ≈ 40-fold-lower affinity at mouse (m) compared with h5-HT2A receptors. Molecular modeling and computational ligand docking studies indicated that the 6-OH moiety of (+)- but not (-)-6-OH-7-Cl-PAT could form a hydrogen bond with serine residue 5.46 of the h5-HT2A receptor. The m5-HT2A as well as m5-HT2B, h5-HT2B, m5-HT2C, and h5-HT2C receptors have alanine at position 5.46, obviating this interaction; (+)-6-OH-7-Cl-PAT also showed ≈ 50-fold lower affinity than (-)-6-OH-7-Cl-PAT at m5-HT2C and h5-HT2C receptors. Mutagenesis studies confirmed that 5-HT2A S5.46 is critical for (+)- but not (-)-6-OH-7-Cl-PAT binding, as well as function. The (+)-6-OH-7-Cl-PAT enantiomer showed partial agonist effects at h5-HT2A wild-type (WT) and m5-HT2A A5.46S point-mutated receptors but did not activate m5-HT2A WT and h5-HT2A S5.46A point-mutated receptors, or h5-HT2B, h5-HT2C, and m5-HT2C receptors; (-)-6-OH-7-Cl-PAT did not activate any of the 5-HT2 receptors. Experiments also included the (2R,4S)-trans-(+)- and (2S,4R)-trans-(-)-enantiomers of 6-methoxy-7-chloro-PAT to validate hydrogen bonding interactions proposed for the corresponding 6-OH analogs. Results indicate that PAT ligand three-dimensional structure impacts target receptor binding and translational outcomes, supporting the hypothesis that GPCR ligand structure governs orthosteric binding pocket molecular determinants and resulting pharmacology.
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Affiliation(s)
- Clinton E Canal
- Center for Drug Discovery (C.E.C., T.C.-S., Y.L., R.G.B.), Department of Pharmaceutical Sciences (C.E.C., T.C.-S., Y.L., R.G.B.), and Department of Chemistry and Chemical Biology (R.G.B.), Northeastern University, Boston, Massachusetts; and Department of Medicinal Chemistry (M.S.K., T.C.-S.) and Department of Psychiatry (D.M.), University of Florida, Gainesville, Florida
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Córdova-Sintjago T, Sakhuja R, Kondabolu K, Canal CE, Booth RG. Molecular Determinants for Ligand Binding at Serotonin 5-HT 2A and 5-HT 2C GPCRs: Experimental Affinity Results Analyzed by Molecular Modeling and Ligand Docking Studies. Int J Quantum Chem 2012; 112:3807-3814. [PMID: 23913978 PMCID: PMC3729958 DOI: 10.1002/qua.24237] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ligands that activate the serotonin 5-HT2C G protein-coupled receptor (GPCR) may be therapeutic for psychoses, addiction, and other neuropsychiatric disorders. Ligands that are antagonists at the closely related 5-HT2A GPCR also may treat neuropsychiatric disorders; in contrast, 5-HT2A activation may cause hallucinations. 5-HT2C-specific agonist drug design is challenging because 5-HT2 GPCRs share 80% transmembrane (TM) homology, same second messenger signaling, and no crystal structures are reported. To help delineate molecular determinants underlying differential binding and activation of 5-HT2 GPCRs, 5-HT2A, and 5-HT2C homology models were built from the β2-adrenergic GPCR crystal structure and equilibrated in a lipid phosphatidyl choline bilayer performing molecular dynamics simulations. Ligand docking studies at the 5-HT2 receptor models were conducted with the (2R, 4S)- and (2S, 4R)-enantiomers of the novel 5-HT2C agonist/5-HT2A/2B antagonist trans-4-phenyl-N,N-dimethyl-2-aminotetralin (PAT) and its 4'-chlorophenyl congners. Results indicate PAT-5-HT2 molecular interactions especially in TM domain V are important for the (2R, 4S) enantiomer, whereas, TM domain VI and VII interactions are more important for the (2S, 4R) enantiomer.
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Canal CE, Cordova-Sintjago TC, Villa NY, Fang LJ, Booth RG. Drug discovery targeting human 5-HT(2C) receptors: residues S3.36 and Y7.43 impact ligand-binding pocket structure via hydrogen bond formation. Eur J Pharmacol 2011; 673:1-12. [PMID: 22020288 DOI: 10.1016/j.ejphar.2011.10.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 09/27/2011] [Accepted: 10/02/2011] [Indexed: 11/28/2022]
Abstract
Specific activation of serotonin (5-HT) 5-HT(2C) G protein-coupled receptors may be therapeutic for obesity and neuropsychiatric disorders. Mutagenesis coupled with computational and molecular modeling experiments based on the human β₂ adrenergic receptor structure was employed to delineate the interactions of different ligands at human 5-HT(2C) residues D3.32, S3.36 and Y7.43. No binding of the tertiary amine radioligand ([³H]-mesulergine) could be detected when the 5-HT(2C) D3.32 residue was mutated to alanine (D3.32A). The S3.36A point-mutation greatly reduced affinity of primary amine ligands, modestly reduced affinity of a secondary amine, and except for the 5-HT(2C)-specific agonist N(CH₃)₂-PAT, affinity of tertiary amines was unaffected. Molecular modeling results indicated that the primary amines form hydrogen bonds with the S3.36 residue, whereas, with the exception of N(CH₃)₂-PAT, tertiary amines do not interact considerably with this residue. The Y7.43A point-mutation greatly reduced affinity of 5-HT, yet reduced to a lesser extent the affinity of tryptamine that lacks the 5-hydroxy moiety present in 5-HT; modeling results indicated that the 5-HT 5-hydroxy moiety hydrogen bonds with Y7.43 at the 5-HT(2C) receptor. Additional modeling results showed that 5-HT induced a hydrogen bond between Y7.43 and D3.32. Finally, modeling results revealed two low-energy binding modes for 5-HT in the 5-HT(2C) binding pocket, supporting the concept that multiple agonist binding modes may stabilize different receptor active conformations to influence signaling. Ligand potencies for modulating WT and point-mutated 5-HT(2C) receptor-mediated phospholipase C activity were in accordance with the affinity data. Ligand efficacies, however, were altered considerably by the S3.36A mutation only.
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Affiliation(s)
- Clinton E Canal
- Department of Medicinal Chemistry, University of Florida, P.O. Box 100485, 1600 SW Archer Road, Gainesville, FL 32610-0485, USA
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Canal CE, Olaghere da Silva UB, Gresch PJ, Watt EE, Sanders-Bush E, Airey DC. The serotonin 2C receptor potently modulates the head-twitch response in mice induced by a phenethylamine hallucinogen. Psychopharmacology (Berl) 2010; 209:163-74. [PMID: 20165943 PMCID: PMC2868321 DOI: 10.1007/s00213-010-1784-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 01/18/2010] [Indexed: 12/25/2022]
Abstract
RATIONALE Hallucinogenic serotonin 2A (5-HT(2A)) receptor partial agonists, such as (+ or -)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), induce a frontal cortex-dependent head-twitch response (HTR) in rodents, a behavioral proxy of a hallucinogenic response that is blocked by 5-HT(2A) receptor antagonists. In addition to 5-HT(2A) receptors, DOI and most other serotonin-like hallucinogens have high affinity and potency as partial agonists at 5-HT(2C) receptors. OBJECTIVES We tested for involvement of 5-HT(2C) receptors in the HTR induced by DOI. RESULTS Comparison of 5-HT(2C) receptor knockout and wild-type littermates revealed an approximately 50% reduction in DOI-induced HTR in knockout mice. Also, pretreatment with either the 5-HT(2C) receptor antagonist SB206553 or SB242084 eradicated a twofold difference in DOI-induced HTR between the standard inbred mouse strains C57BL/6J and DBA/2J, and decreased the DOI-induced HTR by at least 50% in both strains. None of several measures of 5-HT(2A) receptors in frontal cortex explained the strain difference, including 5-HT(2A) receptor density, Galpha(q) or Galpha(i/o) protein levels, phospholipase C activity, or DOI-induced expression of Egr1 and Egr2. 5-HT(2C) receptor density in the brains of C57BL/6J and DBA/2J was also equivalent, suggesting that 5-HT(2C) receptor-mediated intracellular signaling or other physiological modulators of the HTR may explain the strain difference in response to DOI. CONCLUSIONS We conclude that the HTR to DOI in mice is strongly modulated by 5-HT(2C) receptor activity. This novel finding invites reassessment of hallucinogenic mechanisms involving 5-HT(2) receptors.
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MESH Headings
- Aminopyridines/pharmacology
- Amphetamines/pharmacology
- Animals
- Autoradiography
- Behavior, Animal
- Binding Sites
- Blotting, Western
- Brain/drug effects
- Brain/metabolism
- Dose-Response Relationship, Drug
- Drug Partial Agonism
- Early Growth Response Protein 1/genetics
- Early Growth Response Protein 2/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- Hallucinogens/pharmacology
- Head Movements/drug effects
- Indoles/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Knockout
- Pyridines/pharmacology
- RNA, Messenger/metabolism
- Receptor, Serotonin, 5-HT2C/deficiency
- Receptor, Serotonin, 5-HT2C/drug effects
- Receptor, Serotonin, 5-HT2C/genetics
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Species Specificity
- Type C Phospholipases/metabolism
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Olaghere da Silva UB, Morabito MV, Canal CE, Airey DC, Emeson RB, Sanders-Bush E. Impact of RNA editing on functions of the serotonin 2C receptor in vivo. Front Neurosci 2010; 4:26. [PMID: 20582266 PMCID: PMC2858556 DOI: 10.3389/neuro.23.001.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Accepted: 01/20/2010] [Indexed: 01/07/2023] Open
Abstract
Transcripts encoding 5-HT(2C) receptors are modified posttranscriptionally by RNA editing, generating up to 24 protein isoforms. In recombinant cells, the fully edited isoform, 5-HT(2C-VGV), exhibits blunted G-protein coupling and reduced constitutive activity. The present studies examine the signal transduction properties of 5-HT(2C-VGV) receptors in brain to determine the in vivo consequences of altered editing. Using mice solely expressing the 5-HT(2C-VGV) receptor (VGV/Y), we demonstrate reduced G-protein coupling efficiency and high-affinity agonist binding of brain 5-HT(2C-VGV) receptors. However, enhanced behavioral sensitivity to a 5-HT(2C) receptor agonist was also seen in mice expressing 5-HT(2C-VGV) receptors, an unexpected finding given the blunted G-protein coupling. In addition, mice expressing 5-HT(2C-VGV) receptors had greater sensitivity to a 5-HT(2C) inverse agonist/antagonist enhancement of dopamine turnover relative to wild-type mice. These behavioral and biochemical results are most likely explained by increases in 5-HT(2C) receptor binding sites in the brains of mice solely expressing 5-HT(2C-VGV) receptors. We conclude that 5-HT(2C-VGV) receptor signaling in brain is blunted, but this deficiency is masked by a marked increase in 5-HT(2C) receptor binding site density in mice solely expressing the VGV isoform. These findings suggest that RNA editing may regulate the density of 5-HT(2C) receptor binding sites in brain. We further caution that the pattern of 5-HT(2C) receptor RNA isoforms may not reflect the pattern of protein isoforms, and hence the inferred overall function of the receptor.
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Affiliation(s)
| | - Michael V. Morabito
- Center for Molecular Neuroscience, Vanderbilt University School of MedicineNashville, TN, USA
| | - Clinton E. Canal
- Center for Molecular Neuroscience, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of MedicineNashville, TN, USA
| | - David C. Airey
- Center for Molecular Neuroscience, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of MedicineNashville, TN, USA
| | - Ronald B. Emeson
- Center for Molecular Neuroscience, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Psychiatry, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of MedicineNashville, TN, USA
| | - Elaine Sanders-Bush
- Center for Molecular Neuroscience, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Psychiatry, Vanderbilt University School of MedicineNashville, TN, USA
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Canal CE, Mahautmr KC, Cao C, Sanders-Bush E, Airey DC. RNA editing of the serotonin 2C receptor and expression of Galpha(q) protein: genetic mouse models do not support a role for regulation or compensation. J Neurochem 2009; 108:1136-42. [PMID: 19154337 PMCID: PMC2742694 DOI: 10.1111/j.1471-4159.2008.05852.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The serotonin 2C (5-HT(2C)) receptor undergoes RNA editing at five bases in a region of the pre-mRNA encoding the second intracellular loop, generating many unique 5-HT(2C) receptor isoforms. Mechanisms regulating in vivo expression of different edited 5-HT(2C) receptor isoforms are poorly understood, as are the adaptive consequences of variation in editing profiles. Recent findings suggest a putative relationship between expression levels of Galpha(q/11) protein and the degree of editing of 5-HT(2C) receptor transcripts. To elucidate the potential regulatory or adaptive role of Galpha(q/11) protein levels, we quantified editing of 5-HT(2C) receptor RNA transcripts in Galpha(q) null mice and protein levels of Galpha(q) and Galpha(11) in transgenic male mice solely expressing either the non-edited (INI) or the fully edited (VGV) isoforms of the 5-HT(2C) receptor. Pyrosequencing of RNA isolated from amygdaloid cortex in Galpha(q) null and wild-type mice revealed no significant differences in 5-HT(2C) receptor mRNA editing profiles. Cortical tissue from INI/y, VGV/y, and wild-type mice was assayed for expression of Galpha(q) and Galpha(11) subunits by Western blotting. No differences in signal density between wild-type and INI/y or VGV/y groups were found, indicating equivalent levels of Galpha(q) and Galpha(11) protein. Together, these data do not support a causal or compensatory relationship between 5-HT(2C) receptor RNA editing and G(q) protein levels.
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Affiliation(s)
- Clinton E. Canal
- Department of Pharmacology, Vanderbilt University, USA
- Center for Molecular Neuroscience, Vanderbilt University, USA
| | | | - Chike Cao
- Department of Pharmacology, Vanderbilt University, USA
| | - Elaine Sanders-Bush
- Department of Pharmacology, Vanderbilt University, USA
- Center for Molecular Neuroscience, Vanderbilt University, USA
- Department of Psychiatry, Vanderbilt University, USA
| | - David C. Airey
- Department of Pharmacology, Vanderbilt University, USA
- Center for Molecular Neuroscience, Vanderbilt University, USA
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Canal CE, Chang Q, Gold PE. Intra-amygdala injections of CREB antisense impair inhibitory avoidance memory: role of norepinephrine and acetylcholine. Learn Mem 2008; 15:677-86. [PMID: 18772255 PMCID: PMC2632786 DOI: 10.1101/lm.904308] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2008] [Accepted: 07/05/2008] [Indexed: 01/12/2023]
Abstract
Infusions of CREB antisense into the amygdala prior to training impair memory for aversive tasks, suggesting that the antisense may interfere with CRE-mediated gene transcription and protein synthesis important for the formation of new memories within the amygdala. However, the amygdala also appears to modulate memory formation in distributed brain sites, through mechanisms that include the release of norepinephrine and acetylcholine within the amygdala. Thus, CREB antisense injections may affect memory by interfering with mechanisms of modulation, rather than storage, of memory. In the present experiment, rats received bilateral intra-amygdala infusions of CREB antisense (2 nmol/1 microL) 6 h prior to inhibitory avoidance training. In vivo microdialysis samples were collected from the right amygdala before, during, and following training. CREB antisense produced amnesia tested at 48 h after training. In addition, CREB antisense infusions dampened the training-related release of norepinephrine, and to a lesser extent of acetylcholine, in the amygdala. Furthermore, intra-amygdala infusions of the beta-adrenergic receptor agonist clenbuterol administered immediately after training attenuated memory impairments induced by intra-amygdala injections of CREB antisense. These findings suggest that intra-amygdala treatment with CREB antisense may affect processes involved in modulation of memory in part through interference with norepinephrine and acetylcholine neurotransmission in the amygdala.
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Affiliation(s)
- Clinton E. Canal
- Neuroscience Program, University of Illinois, Urbana–Champaign, Illinois 61820, USA
| | - Qing Chang
- Department of Animal Sciences, Department of Psychology, Department of Psychiatry, Department of Biomedical Engineering, University of Illinois, Urbana–Champaign, Illinois 61820, USA
| | - Paul E. Gold
- Neuroscience Program, University of Illinois, Urbana–Champaign, Illinois 61820, USA
- The Institute for Genomic Biology, University of Illinois, Urbana–Champaign, Illinois 61820, USA
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Abstract
Systemic or intra-hippocampal administration of the protein synthesis inhibitor anisomycin generally leads to impairments in memory tested 24 hr or more after training but spares memory for a few hours after training. Thus, amnesia does not appear immediately after training but develops with time, findings most often interpreted as evidence for distinct short- and long-term memory processes. However, time courses for the onset of amnesia vary substantially after treatment with protein synthesis inhibitors. Some of the variability across experiments may reflect task-related differences or, perhaps relatedly, may reflect memory processing mediated by different neural systems. In the present experiments, anisomycin was infused into either the hippocampus or the amygdala 20 min before inhibitory avoidance training. Similar to previous findings, intra-hippocampus injections of anisomycin impaired memory tested 48 hr after training yet spared memory tested 4 hr after training. In contrast, intra-amygdala injections of anisomycin impaired memory tested at 0.5, 4, and 48 hr after training, revealing no evidence for spared memory at short times after training. The distinct temporal properties for amnesia following anisomycin injections into the hippocampus or amygdala may reflect different consequences for memory of perturbations of the neural system in which the manipulation is made.
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Affiliation(s)
- Clinton E Canal
- Neuroscience Program, University of Illinois, 603 East Daniel Street, Champaign, IL 61820, USA
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Canal CE, Chang Q, Gold PE. Amnesia produced by altered release of neurotransmitters after intraamygdala injections of a protein synthesis inhibitor. Proc Natl Acad Sci U S A 2007; 104:12500-5. [PMID: 17640910 PMCID: PMC1941498 DOI: 10.1073/pnas.0705195104] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Indexed: 12/18/2022] Open
Abstract
Amnesia produced by protein synthesis inhibitors such as anisomycin provides major support for the prevalent view that the formation of long-lasting memories requires de novo protein synthesis. However, inhibition of protein synthesis might disrupt other neural functions to interfere with memory formation. Intraamygdala injections of anisomycin before inhibitory avoidance training impaired memory in rats tested 48 h later. Release of norepinephrine (NE), dopamine (DA), and serotonin, measured at the site of anisomycin infusions, increased quickly by approximately 1,000-17,000%, far above the levels seen under normal conditions. NE and DA release later decreased far below baseline for several hours before recovering at 48 h. Intraamygdala injections of a beta-adrenergic receptor antagonist or agonist, each timed to blunt effects of increases and decreases in NE release after anisomycin, attenuated anisomycin-induced amnesia. In addition, similar to the effects on memory seen with anisomycin, intraamygdala injections of a high dose of NE before training impaired memory tested at 48 h after training. These findings suggest that altered release of neurotransmitters may mediate amnesia produced by anisomycin and, further, raise important questions about the empirical bases for many molecular theories of memory formation.
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Affiliation(s)
| | | | - Paul E. Gold
- *Neuroscience Program
- Psychology, and
- Psychiatry, and
- Institute for Genomic Biology, University of Illinois at Urbana–Champaign, Champaign, IL 61820
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McNay EC, Canal CE, Sherwin RS, Gold PE. Modulation of memory with septal injections of morphine and glucose: effects on extracellular glucose levels in the hippocampus. Physiol Behav 2005; 87:298-303. [PMID: 16343563 DOI: 10.1016/j.physbeh.2005.10.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Revised: 09/19/2005] [Accepted: 10/19/2005] [Indexed: 11/26/2022]
Abstract
The concentration of glucose in the extracellular fluid (ECF) of the hippocampus decreases substantially during memory testing on a hippocampus-dependent memory task. Administration of exogenous glucose, which enhances task performance, prevents this decrease, suggesting a relationship between hippocampal glucose availability and memory performance. In the present experiment, spontaneous alternation performance and task-related changes in hippocampal ECF glucose were assessed in rats after intraseptal administration of morphine, which impairs memory on a spontaneous alternation task, and after co-administration of intraseptal glucose, which attenuates that impairment. Consistent with previous findings, spontaneous alternation testing resulted in a decrease in hippocampal ECF glucose levels in control rats. However, rats that received intraseptal morphine prior to testing showed memory impairments and an absence of the task-related decrease in hippocampal ECF glucose levels. Intraseptal co-administration of glucose with morphine attenuated the memory impairment, and ECF glucose levels in the hippocampus decreased in a manner comparable to that seen in control rats. These data suggest that fluctuations in hippocampal ECF glucose levels may be a marker of mnemonic processing and support the view that decreases in extracellular glucose during memory testing reflect increased glucose demand during memory processing.
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Affiliation(s)
- Ewan C McNay
- Section of Endocrinology, Yale University School of Medicine, USA
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Canal CE, Stutz SJ, Gold PE. Glucose injections into the dorsal hippocampus or dorsolateral striatum of rats prior to T-maze training: modulation of learning rates and strategy selection. Learn Mem 2005; 12:367-74. [PMID: 16027177 PMCID: PMC1183254 DOI: 10.1101/lm.88205] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The present experiments examined the effects of injecting glucose into the dorsal hippocampus or dorsolateral striatum on learning rates and on strategy selection in rats trained on a T-maze that can be solved by using either a hippocampus-sensitive place or striatum-sensitive response strategy. Percentage strategy selection on a probe trial (P(crit)) administered after rats achieved criterion (nine of 10 correct choices) varied by group. All groups predominately exhibited a response strategy on a probe trial administered after overtraining, i.e., after 90 trials. In experiment 1, rats that received intrahippocampal glucose injections showed enhanced acquisition of the T-maze and showed increased use of response solutions at P(crit) compared with that of unimplanted and artificial cerebral spinal fluid (aCSF)-treated groups. These findings suggest that glucose enhanced hippocampal functions to accelerate the rate of learning and the early adoption of a response strategy. In experiment 2, rats that received intrastriatal glucose injections exhibited place solutions early in training and reached criterion more slowly than did aCSF controls, with learning rates comparable to those of unoperated and operated-uninjected controls. Relative to unoperated, operated-uninjected and glucose-injected rats, rats that received intrastriatal aCSF injections showed enhanced acquisition of the T-maze and increased use of response solutions at P(crit). The unexpected enhanced acquisition seen after striatal aCSF injections suggests at least two possible interpretations: (1) aCSF impaired striatal function, thereby releasing competition with the hippocampus and ceding control over learning to the hippocampus during early training trials; and (2) aCSF enhanced striatal functioning to facilitate striatal-sensitive learning. With either interpretation, the results indicate that intrastriatal glucose injections compensated for the aCSF-induced effect. Finally, enhanced acquisition regardless of treatment was accompanied by rapid adoption of a response solution for the T-maze.
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Affiliation(s)
- Clinton E Canal
- The Neuroscience Program,University of Illinois, Urbana-Champaign, IL 61820, USA
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Canal CE, McNay EC, Gold PE. Increases in extracellular fluid glucose levels in the rat hippocampus following an anesthetic dose of pentobarbital or ketamine-xylazine: an in vivo microdialysis study. Physiol Behav 2004; 84:245-50. [PMID: 15708776 DOI: 10.1016/j.physbeh.2004.11.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Revised: 11/22/2004] [Accepted: 11/30/2004] [Indexed: 10/26/2022]
Abstract
Using in vivo microdialysis, we examined glucose levels in the extracellular fluid (ECF) of the hippocampus and in the blood prior to and during pentobarbital (45 mg/kg) or ketamine-xylazine (66 mg/kg, 7 mg/kg) anesthesia. Anesthesia with either pentobarbital or ketamine-xylazine significantly increased hippocampal ECF glucose levels (mean peak increases of +71% and +85%, respectively). In addition, there were substantial increases in blood glucose levels (mean peak increases of +24% and +30%, respectively). The increased levels of hippocampal ECF glucose during anesthesia complement past evidence for decreases in ECF glucose in the hippocampus observed while rats perform a memory task sensitive to hippocampal damage, providing further support for the view that ECF glucose levels in the hippocampus are dynamically coupled to local neural activity.
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Affiliation(s)
- Clinton E Canal
- The Neuroscience Program, University of Illinois, Champaign, IL 61820, USA
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