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Malar DS, Thitilertdecha P, Ruckvongacheep KS, Brimson S, Tencomnao T, Brimson JM. Targeting Sigma Receptors for the Treatment of Neurodegenerative and Neurodevelopmental Disorders. CNS Drugs 2023; 37:399-440. [PMID: 37166702 PMCID: PMC10173947 DOI: 10.1007/s40263-023-01007-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/18/2023] [Indexed: 05/12/2023]
Abstract
The sigma-1 receptor is a 223 amino acid-long protein with a recently identified structure. The sigma-2 receptor is a genetically unrelated protein with a similarly shaped binding pocket and acts to influence cellular activities similar to the sigma-1 receptor. Both proteins are highly expressed in neuronal tissues. As such, they have become targets for treating neurological diseases, including Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), multiple sclerosis (MS), Rett syndrome (RS), developmental and epileptic encephalopathies (DEE), and motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). In recent years, there have been many pre-clinical and clinical studies of sigma receptor (1 and 2) ligands for treating neurological disease. Drugs such as blarcamesine, dextromethorphan and pridopidine, which have sigma-1 receptor activity as part of their pharmacological profile, are effective in treating multiple aspects of several neurological diseases. Furthermore, several sigma-2 receptor ligands are under investigation, including CT1812, rivastigmine and SAS0132. This review aims to provide a current and up-to-date analysis of the current clinical and pre-clinical data of drugs with sigma receptor activities for treating neurological disease.
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Affiliation(s)
- Dicson S Malar
- Natural Products for Neuroprotection and Anti-ageing Research Unit, Chulalongkorn University, Bangkok, Thailand
| | - Premrutai Thitilertdecha
- Siriraj Research Group in Immunobiology and Therapeutic Sciences, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Kanokphorn S Ruckvongacheep
- Department of Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Sirikalaya Brimson
- Department of Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Tewin Tencomnao
- Natural Products for Neuroprotection and Anti-ageing Research Unit, Chulalongkorn University, Bangkok, Thailand
| | - James M Brimson
- Natural Products for Neuroprotection and Anti-ageing Research Unit, Chulalongkorn University, Bangkok, Thailand.
- Research, Innovation and International Affairs, Faculty of Allied Health Sciences, Chulalongkorn University, Room 409, ChulaPat-1 Building, 154 Rama 1 Road, Bangkok, 10330, Thailand.
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Chen J, Li G, Qin P, Chen J, Ye N, Waddington JL, Zhen X. Allosteric Modulation of the Sigma-1 Receptor Elicits Antipsychotic-like Effects. Schizophr Bull 2022; 48:474-484. [PMID: 34865170 PMCID: PMC8886599 DOI: 10.1093/schbul/sbab137] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Allosteric modulation represents an important approach in drug discovery because of its advantages in safety and selectivity. SOMCL-668 is the first selective and potent sigma-1 receptor allosteric modulator, discovered in our laboratory. The present work investigates the potential therapeutic effects of SOMCL-668 on phencyclidine (PCP)-induced schizophrenia-related behavior in mice and further elucidates underlying mechanisms for its antipsychotic-like effects. SOMCL-668 not only attenuated acute PCP-induced hyperactivity and PPI disruption, but also ameliorated social deficits and cognitive impairment induced by chronic PCP treatment. Pretreatment with the selective sigma-1 receptor antagonist BD1047 blocked the effects of SOMCL-668, indicating sigma-1 receptor-mediated responses. This was confirmed using sigma-1 receptor knockout mice, in which SOMCL-668 failed to ameliorate PPI disruption and hyperactivity induced by acute PCP and social deficits and cognitive impairment induced by chronic PCP treatment. Additionally, in vitro SOMCL-668 exerted positive modulation of sigma-1 receptor agonist-induced intrinsic plasticity in brain slices recorded by patch-clamp. Furthermore, in vivo lower dose of SOMCL-668 exerted positive modulation of improvement in social deficits and cognitive impairment induced by the selective sigma-1 agonist PRE084. Also, SOMCL-668 reversed chronic PCP-induced down-regulation in expression of frontal cortical p-AKT/AKT, p-CREB/CREB and BDNF in wide-type but not sigma-1 knockout mice. Moreover, administration of the PI3K/AKT inhibitor LY294002 abolished amelioration by SOMCL-668 of chronic PCP-induced schizophrenia-related behaviors by inhibition of BDNF expression. The present data provide initial, proof-of-concept evidence that allosteric modulation of the sigma-1 receptor may be a novel approach for the treatment of psychotic illness.
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Affiliation(s)
- Jiali Chen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Guangying Li
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Pingping Qin
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Jiaojiao Chen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Na Ye
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - John L Waddington
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland
| | - Xuechu Zhen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
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Martin P, Reeder T, Sourbron J, de Witte PAM, Gammaitoni AR, Galer BS. An Emerging Role for Sigma-1 Receptors in the Treatment of Developmental and Epileptic Encephalopathies. Int J Mol Sci 2021; 22:8416. [PMID: 34445144 PMCID: PMC8395113 DOI: 10.3390/ijms22168416] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 12/14/2022] Open
Abstract
Developmental and epileptic encephalopathies (DEEs) are complex conditions characterized primarily by seizures associated with neurodevelopmental and motor deficits. Recent evidence supports sigma-1 receptor modulation in both neuroprotection and antiseizure activity, suggesting that sigma-1 receptors may play a role in the pathogenesis of DEEs, and that targeting this receptor has the potential to positively impact both seizures and non-seizure outcomes in these disorders. Recent studies have demonstrated that the antiseizure medication fenfluramine, a serotonin-releasing drug that also acts as a positive modulator of sigma-1 receptors, reduces seizures and improves everyday executive functions (behavior, emotions, cognition) in patients with Dravet syndrome and Lennox-Gastaut syndrome. Here, we review the evidence for sigma-1 activity in reducing seizure frequency and promoting neuroprotection in the context of DEE pathophysiology and clinical presentation, using fenfluramine as a case example. Challenges and opportunities for future research include developing appropriate models for evaluating sigma-1 receptors in these syndromic epileptic conditions with multisystem involvement and complex clinical presentation.
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Affiliation(s)
- Parthena Martin
- Zogenix, Inc., Emeryville, CA 94608, USA; (P.M.); (T.R.); (A.R.G.)
| | - Thadd Reeder
- Zogenix, Inc., Emeryville, CA 94608, USA; (P.M.); (T.R.); (A.R.G.)
| | - Jo Sourbron
- University Hospital KU Leuven, 3000 Leuven, Belgium;
| | - Peter A. M. de Witte
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences at KU Leuven, 3000 Leuven, Belgium;
| | | | - Bradley S. Galer
- Zogenix, Inc., Emeryville, CA 94608, USA; (P.M.); (T.R.); (A.R.G.)
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Lever JR, Fergason-Cantrell EA. Allosteric modulation of sigma receptors by BH3 mimetics ABT-737, ABT-263 (Navitoclax) and ABT-199 (Venetoclax). Pharmacol Res 2019; 142:87-100. [PMID: 30721730 DOI: 10.1016/j.phrs.2019.01.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/12/2018] [Accepted: 01/21/2019] [Indexed: 11/21/2022]
Abstract
ABT-737, ABT-263 (Navitoclax) and ABT-199 (Venetoclax) are under intensive preclinical and clinical investigation as treatments for hematologic and other malignancies. These small molecules mimic pro-death B-cell lymphoma-2 (Bcl-2) Homology 3 (BH3) domain-only proteins. They also bear a structural resemblance to certain sigma (σ) receptor ligands. Moreover, the Bcl-2 and σ receptor protein families are both located primarily at the endoplasmic reticulum, mediate cell death and survival through protein-protein interactions, and physically associate. Accordingly, we examined the ability of the ABT series of BH3 mimetics to interact with σ receptors using radioligand-binding techniques. Negative allosteric modulation of [3H](+)-pentazocine, an agonist, binding to σ1 receptors in guinea pig brain membranes was observed for ABT-737, ABT-263 and ABT-199. Findings included reduction of specific binding to distinct plateaus in concentration-dependent fashion, significant slowing of radioligand dissociation kinetics, and decreases in radioligand affinity with no or modest changes in maximal receptor densities. Using a ternary complex model, dissociation constants (KX) for modulator binding to the σ1 receptor ranged from 1 to 2.5 μM, while negative cooperativity factors (α), representing the changes in affinity of ligand and modulator when bound as a ternary complex with the receptor, ranged from 0.15 to 0.42. These observations were extended and reinforced by studies using intact small cell (NCI-H69) and non-small cell (NCI-H23) lung cancer cells, and by using an antagonist σ1 receptor radioligand, E-N-1-(3'-[125I]iodoallyl)-N'-4-(3″,4″-dimethoxyphenethyl)piperazine, in mouse brain membranes. By contrast, exploratory studies indicate marked enhancement of the σ2 receptor binding of [3H]1,3-di-(o-tolyl)guanidine/(+)-pentazocine in NCI-H23 cells and guinea pig brain membranes. These findings raise intriguing questions regarding mechanism and potential functional outcomes.
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Affiliation(s)
- John R Lever
- Department of Radiology, University of Missouri, Columbia, MO 65211, USA; Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA.
| | - Emily A Fergason-Cantrell
- Department of Radiology, University of Missouri, Columbia, MO 65211, USA; Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA
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Vavers E, Zvejniece L, Maurice T, Dambrova M. Allosteric Modulators of Sigma-1 Receptor: A Review. Front Pharmacol 2019; 10:223. [PMID: 30941035 PMCID: PMC6433746 DOI: 10.3389/fphar.2019.00223] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/22/2019] [Indexed: 11/13/2022] Open
Abstract
Allosteric modulators of sigma-1 receptor (Sig1R) are described as compounds that can increase the activity of some Sig1R ligands that compete with (+)-pentazocine, one of the classic prototypical ligands that binds to the orthosteric Sig1R binding site. Sig1R is an endoplasmic reticulum membrane protein that, in addition to its promiscuous high-affinity ligand binding, has been shown to have chaperone activity. Different experimental approaches have been used to describe and validate the activity of allosteric modulators of Sig1R. Sig1R-modulatory activity was first found for phenytoin, an anticonvulsant drug that primarily acts by blocking the voltage-gated sodium channels. Accumulating evidence suggests that allosteric Sig1R modulators affect processes involved in the pathophysiology of depression, memory and cognition disorders as well as convulsions. This review will focus on the description of selective and non-selective allosteric modulators of Sig1R, including molecular structure properties and pharmacological activity both in vitro and in vivo, with the aim of providing the latest overview from compound discovery approaches to eventual clinical applications. In this review, the possible mechanisms of action will be discussed, and future challenges in the development of novel compounds will be addressed.
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Affiliation(s)
- Edijs Vavers
- Laboratory of Pharmaceutical Pharmacology, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Liga Zvejniece
- Laboratory of Pharmaceutical Pharmacology, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Tangui Maurice
- MMDN, University of Montpellier, INSERM, EPHE, UMR-S1198, Montpellier, France
| | - Maija Dambrova
- Laboratory of Pharmaceutical Pharmacology, Latvian Institute of Organic Synthesis, Riga, Latvia
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Remesic M, Hruby VJ, Porreca F, Lee YS. Recent Advances in the Realm of Allosteric Modulators for Opioid Receptors for Future Therapeutics. ACS Chem Neurosci 2017; 8:1147-1158. [PMID: 28368571 DOI: 10.1021/acschemneuro.7b00090] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Opioids, and more specifically μ-opioid receptor (MOR) agonists such as morphine, have long been clinically used as therapeutics for severe pain states but often come with serious side effects such as addiction and tolerance. Many studies have focused on bringing about analgesia from the MOR with attenuated side effects, but its underlying mechanism is not fully understood. Recently, focus has been geared toward the design and elucidation of the orthosteric site with ligands of various biological profiles and mixed subtype opioid activities and selectivities, but targeting the allosteric site is an area of increasing interest. It has been shown that allosteric modulators play key roles in influencing receptor function such as its tolerance to a ligand and affect downstream pathways. There has been a high variance of chemical structures that provide allosteric modulation at a given receptor, but recent studies and reviews tend to focus on the altered cellular mechanisms instead of providing a more rigorous description of the allosteric ligand's structure-function relationship. In this review, we aim to explore recent developments in the structural motifs that potentiate orthosteric binding and their influences on cellular pathways in an effort to present novel approaches to opioid therapeutic design.
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Affiliation(s)
- Michael Remesic
- Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Victor J. Hruby
- Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Frank Porreca
- Department
of Pharmacology, University of Arizona, Tucson, Arizona 85719, United States
| | - Yeon Sun Lee
- Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
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Abstract
This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ1R) and sigma receptor two (σ2R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a subtype of opioid receptors and was suggested to contribute to the delusions and psychoses induced by benzomorphans such as SKF-10047 and pentazocine. Later studies confirmed that σRs are non-opioid receptors (not an µ opioid receptor) and play a more diverse role in intracellular signaling, apoptosis and metabolic regulation. σ1Rs are intracellular receptors acting as chaperone proteins that modulate Ca2+ signaling through the IP3 receptor. They dynamically translocate inside cells, hence are transmembrane proteins. The σ1R receptor, at the mitochondrial-associated endoplasmic reticulum membrane, is responsible for mitochondrial metabolic regulation and promotes mitochondrial energy depletion and apoptosis. Studies have demonstrated that they play a role as a modulator of ion channels (K+ channels; N-methyl-d-aspartate receptors [NMDAR]; inositol 1,3,5 triphosphate receptors) and regulate lipid transport and metabolism, neuritogenesis, cellular differentiation and myelination in the brain. σ1R modulation of Ca2+ release, modulation of cardiac myocyte contractility and may have links to G-proteins. It has been proposed that σ1Rs are intracellular signal transduction amplifiers. This review of the literature examines the mechanism of action of the σRs, their interaction with neurotransmitters, pharmacology, location and adverse effects mediated through them.
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Affiliation(s)
- Colin G Rousseaux
- a Department of Pathology and Laboratory Medicine , University of Ottawa , Ottawa , ON , Canada and
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Abstract
INTRODUCTION Neuropathic pain is difficult to relieve with standard analgesics and tends to be resistant to opioid therapy. Sigma-1 receptors activated during neuropathic injury may sustain pain. Neuropathic injury activates sigma-1 receptors, which results in activation of various kinases, modulates the activity of multiple ion channels, ligand activated ion channels and voltage-gated ion channels; alters monoamine neurotransmission and dampens opioid receptors G-protein activation. Activation of sigma-1 receptors tonically inhibits opioid receptor G-protein activation and thus dampens analgesic responses. Therefore, sigma-1 receptor antagonists are potential analgesics for neuropathic and adjuvants to opioid therapy. AREAS COVERED This article reviews the importance of sigma-1 receptors as pain generators in multiple animal models in order to illustrate both the importance of these unique receptors in pathologic pain and the potential benefits to sigma-1 receptor antagonists as analgesics. EXPERT OPINION Sigma-1 receptor antagonists have a great potential as analgesics for acute neuropathic injury (herpes zoster, acute postoperative pain and chemotherapy induced neuropathy) and may, as an additional benefit, prevent the development of chronic neuropathic pain. Antagonists are potentially effective as adjuvants to opioid therapy when used early to prevent analgesic tolerance. Drug development is complicated by the complexity of sigma-1 receptor pharmacodynamics and its multiple targets, the lack of a specific sigma-1 receptor antagonist, and potential side effects due to on-target toxicities (cognitive impairment, depression).
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Affiliation(s)
- Mellar P Davis
- Case Western Reserve University, Taussig Cancer Institute, Cleveland Clinic Lerner School of Medicine, Palliative Medicine and Supportive Oncology Services, Division of Solid Tumor, The Cleveland Clinic , 9500 Euclid Ave, Cleveland, OH 44195 , USA
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Characterization of pulmonary sigma receptors by radioligand binding. Eur J Pharmacol 2015; 762:118-26. [PMID: 26004528 DOI: 10.1016/j.ejphar.2015.05.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 05/11/2015] [Accepted: 05/18/2015] [Indexed: 11/20/2022]
Abstract
This study establishes the expression of appreciable populations of sites on mouse lung membranes that exhibit radioligand binding properties and pharmacology consistent with assignment as sigma1 and sigma2 receptors. Specific binding of the sigma1 receptor radioligand [(3)H](+)-pentazocine reached steady state within 6h at 37°C. Saturation studies revealed high affinity binding to a single class of sites (Kd 1.36±0.04nM; Bmax 967±11fmol/mg protein). Inhibition studies showed appropriate sigma1 receptor pharmacology, including higher affinity for (+)-N-allylnormetazocine with respect to the (-)-enantiomer, and positive allosteric modulation of dextromethorphan binding by phenytoin. Using [(3)H]1,3-di(2-tolyl)guanidine in the presence of (+)-pentazocine to assess sigma2 receptor binding, steady state was achieved within 2min at 25°C. Cold saturation studies revealed one high affinity, low capacity binding site (Kd 31.8±8.3nM; Bmax 921±228fmol/mg protein) that displayed sigma2 receptor pharmacology. A very low affinity, high capacity interaction also was observed that represents saturable, but not sigma receptor specific, binding. A panel of ligands showed rank order inhibition of radioligand binding appropriate for the sigma2 receptor, with ifenprodil displaying the highest apparent affinity. In vivo, dextromethorphan inhibited the specific binding of a radioiodinated sigma1 receptor ligand in lung with an ED50 of 1.2μmol/kg, a value near the recommended dosage for the drug as a cough suppressant. Overall, the present work provides a foundation for studies of drug interactions with pulmonary sigma1 and sigma2 receptors in vitro and in vivo.
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Nguyen VH, Pham T, Fookes C, Berghofer P, Greguric I, Arthur A, Mattner F, Rahardjo G, Davis E, Howell N, Gregoire MC, Katsifis A, Shepherd R. Synthesis and biological characterisation of 18F-SIG343 and 18F-SIG353, novel and high selectivity σ2 radiotracers, for tumour imaging properties. EJNMMI Res 2013; 3:80. [PMID: 24330526 PMCID: PMC3878827 DOI: 10.1186/2191-219x-3-80] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 11/21/2013] [Indexed: 12/13/2022] Open
Abstract
Background Sigma2 (σ2) receptors are highly expressed in cancer cell lines and in tumours. Two novel selective 18F-phthalimido σ2 ligands, 18F-SIG343 and 18F-SIG353, were prepared and characterised for their potential tumour imaging properties. Methods Preparation of 18F-SIG343 and 18F-SIG353 was achieved via nucleophilic substitution of their respective nitro precursors. In vitro studies including radioreceptor binding assays in the rat brain membrane and cell uptake studies in the A375 cell line were performed. In vivo studies were carried out in mice bearing A375 tumours including positron emission tomography (PET) imaging, biodistribution, blocking and metabolite studies. Results In vitro studies showed that SIG343 and SIG353 displayed excellent affinity and selectivity for σ2 receptors (Ki(σ2) = 8 and 3 nM, σ2:σ1 = 200- and 110-fold, respectively). The σ2 selectivity of 18F-SIG343 was further confirmed by blocking studies in A375 cells, however, not noted for 18F-SIG353. Biodistribution studies showed that both radiotracers had similar characteristics including moderately high tumour uptake (4%ID/g to 5%ID/g); low bone uptake (3%ID/g to 4%ID/g); and high tumour-to-muscle uptake ratios (four- to sevenfold) up to 120 min. Although radiotracer uptake in organs known to express σ receptors was significantly blocked by pre-injection of competing σ ligands, the blocking effect was not observed in the tumour. PET imaging studies indicated major radioactive localisation in the chest cavity for both ligands, with approximately 1%ID/g uptake in the tumour at 120 min. Metabolite studies showed that the original radiotracers remained unchanged 65% to 80% in the tumour up to 120 min. Conclusions The lead ligands showed promising in vitro and in vivo characteristics. However, PET imaging indicated low tumour-to-background ratios. Furthermore, we were unable to demonstrate that uptake in the A375 tumour was σ2-specific. 18F-SIG343 and 18F-SIG343 do not display ideal properties for imaging the σ2 receptor in the A375 tumour model. However, since the radiotracers show promising in vitro and in vivo characteristics, longer scans using appropriate half-life isotopes and alternative tumour models will be carried out in future studies to fully validate the imaging characteristics of these radiotracers.
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Affiliation(s)
- Vu H Nguyen
- LifeSciences, ANSTO, Locked Bag 2001, Kirrawee, New South Wales 2232, Australia.
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Guo L, Zhao J, Jin G, Zhao B, Wang G, Zhang A, Zhen X. SKF83959 is a potent allosteric modulator of sigma-1 receptor. Mol Pharmacol 2013; 83:577-86. [PMID: 23295385 DOI: 10.1124/mol.112.083840] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
SKF83959 (3-methyl-6-chloro-7,8-hydroxy-1-[3-methylphenyl]-2,3,4,5-tetrahydro-1H-3-benzazepine), an atypical dopamine receptor-1 (D(1) receptor) agonist, has shown many D(1) receptor-independent effects, such as neuroprotection, blockade of Na(+) channel, and promotion of spontaneous glutamate release, which resemble the effects of the sigma-1 receptor activation. In the present work, we explored the potential modulation of SKF83959 on the sigma-1 receptor. The results indicated that SKF83959 dramatically promoted the binding of (3)H(+)-pentazocine (a selective sigma-1 receptor agonist) to the sigma-1 receptor in brain and liver tissues but produced no effect on (3)H-progesterone binding (a sigma-1 receptor antagonist). The saturation assay and the dissociation kinetics assay confirmed the allosteric effect. We further demonstrated that the SKF83959 analogs, such as SCH22390 [(R)-(1)-7-chloro-8- hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride] and SKF38393 [(+/-)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrobromide], also showed the similar allosteric effect on the sigma-1 receptor in the liver tissue but not in the brain tissue. Moreover, all three tested chemicals elicited no significant effect on (3)H-1,3-di(2-tolyl)-guanidine ((3)H-DTG) binding to the sigma-2 receptor. The present data uncovered a new role of SKF83959 and its analogs on the sigma-1 receptor, which, in turn, may reveal the underlying mechanism for the D(1) receptor-independent effect of the drug.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/analogs & derivatives
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Allosteric Regulation/drug effects
- Animals
- Brain/drug effects
- Brain/metabolism
- Cell Line
- Drug Synergism
- HEK293 Cells
- Humans
- Liver/drug effects
- Liver/metabolism
- Male
- Pentazocine/pharmacology
- Progesterone/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/metabolism
- Receptors, sigma/agonists
- Receptors, sigma/antagonists & inhibitors
- Receptors, sigma/metabolism
- Sigma-1 Receptor
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Affiliation(s)
- Lin Guo
- Department of Pharmacology II, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
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Cobos EJ, Lucena G, Baeyens JM, Del Pozo E. Differences in the allosteric modulation by phenytoin of the binding properties of the σ1 ligands [3H](+)-pentazocine and [3H]NE-100. Synapse 2005; 59:152-61. [PMID: 16342057 DOI: 10.1002/syn.20230] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The present study evaluated the effects of phenytoin (DPH) on the binding to synaptosomal fraction membranes from guinea pig brain of the prototypic sigma1 (sigma1) receptor agonist [3H](+)-pentazocine and the putative sigma1 antagonist [3H]NE-100. Equilibrium and binding kinetics studies were done. The order of affinity of 12 sigma1 ligands for binding sites labeled with [3H](+)-pentazocine correlated well with their order of affinity for sites labeled with [3H]NE-100, suggesting that both radioligands label the same receptor. Phenytoin increased the binding of [3H](+)-pentazocine, enhancing its affinity (K(D) value) for sigma1 receptors and decreasing its dissociation rate from these receptors. The maximal number of receptors (B(max) value) labeled with [3H](+)-pentazocine was not changed. In contrast, phenytoin decreased the specific binding and maximal number of receptors labeled with [3H]NE-100, and increased its dissociation rate from sigma1 receptors. The affinity of this radioligand for sigma1 receptors was not modified. In conclusion, phenytoin behaved as a positive allosteric modulator on the binding of [3H](+)-pentazocine, whereas it negatively modulated the binding of [3H]NE-100. These results add evidence in favor of the use of phenytoin in vitro to distinguish between agonists and antagonists of sigma1 receptors.
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Affiliation(s)
- Enrique J Cobos
- Department of Pharmacology and Institute of Neuroscience, School of Medicine,University of Granada, 18012 Granada, Spain
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Jahng JW, Zhang TY, Lee S, Kim DG. Effects of dextromethorphan on nocturnal behavior and brain c-Fos expression in adolescent rats. Eur J Pharmacol 2001; 431:47-52. [PMID: 11716842 DOI: 10.1016/s0014-2999(01)01409-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dextromethorphan, an antitussive widely available over-the-counter, is abused, mostly by teenagers at high doses. In our previous report, a high dose of dextromethorphan activated the midbrain dopamine neurons of adolescent rats. In the present study, we performed c-Fos immunohistochemistry in the dopaminergic terminal regions of adolescent rat brain after the intraperitoneal administration of dextromethorphan at different doses (0, 10, 20, and 40 mg/kg), and also examined the effects on nocturnal behavior. The results showed that dextromethorphan increased c-Fos expression dose dependently in the anterior cingulate cortex, caudate putamen, nucleus accumbens, and central amygdala. Significant ataxia occurred and both locomotor and rearing activity decreased immediately after the dextromethorphan injection. We conclude that the neurons in the reward pathway of the adolescent rat brain appear to be activated by a single injection of dextromethorphan, and that activation of this pathway by dextromethorphan may correlate with the behavioral effects and abuse potential of the drug.
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Affiliation(s)
- J W Jahng
- Department of Pharmacology and Yonsei Brain Research Institute, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, 120-752, Seoul, South Korea
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14
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Abstract
Recently, in an attempt to isolate the nonopioid sigma receptor, Su and colleagues purified a protein from rat liver and brain which appeared to resemble the original sigma opioid receptor as proposed by Martin in 1976, and for which the nonopiate sigma-1 ligand (+)pentazocine presents a high affinity. Previous in vivo electrophysiological studies from our laboratory have demonstrated that several selective sigma-1 ligands potentiate the neuronal response to NMDA. The goal of the present series of experiments was to assess the effects of some selective sigma-1 ligands on the potentiation of the NMDA response and to determine if this potentiation was mediated by the naloxone-sensitive sigma receptor. Extracellular unitary recordings from pyramidal neurons of the CA3 region of the rat dorsal hippocampus were obtained. The sigma-1 ligands BD 737, L 687-384, and JO-1784 (igmesine), administered intravenously at low doses, potentiated the NMDA response but the opiate antagonist naloxone failed to reverse this potentiation. However, the potentiation of the NMDA response induced by the sigma-1 ligand (+)pentazocine was suppressed by naloxone but not by the mu antagonist cyprodime hydrobomide, the kappa antagonist DIPPA nor by the delta antagonist naltrindole. (+/-) Cyclazocine, which presents a high affinity for the above-mentioned sigma-opiate receptor acted as an antagonist by suppressing the potentiation of the NMDA response induced by both JO-1784 and (+)pentazocine. These results suggest that the effects induced by some sigma-1 ligands may, in fact, be sensitive to naloxone while others may not. The original classification of sigma receptors as opiates might have been partly accurate.
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Affiliation(s)
- S Couture
- University of Ottawa, Ottawa, Ontario, Canada
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15
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Ronsisvalle G, Marrazzo A, Prezzavento O, Pasquinucci L, Falcucci B, Di Toro RD, Spampinato S. Substituted 1-phenyl-2-cyclopropylmethylamines with high affinity and selectivity for sigma sites. Bioorg Med Chem 2000; 8:1503-13. [PMID: 10896126 DOI: 10.1016/s0968-0896(00)00072-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A series of 1-phenyl-2-cyclopropylmethylamines structurally related to (+)- and (-)-MPCB were synthesized and their binding affinities for sigma1, sigma2, opioid and dopamine (D2) receptors were evaluated. Substitution of the cis-N-normetazocine with different aminic moieties provided compounds with high affinity and selectivity for sigma binding sites with respect to opioid and dopamine (D2) receptors. The observed increase in sigma2 affinity as compared to the parent (+)-MPCB, supports the idea that the particular stereochemistry of (+)-cis-N-normetazocine affects sigma1 selectivity but does not affect sigma1 affinity. The (+/-)-cis isomers of methyl 2-[(1-adamantylamino)methyl]-1-phenylcyclopropane-1-carboxyl ate (18) displayed a higher affinity and selectivity for the sigma1 and sigma2 receptor subtypes compared to the (+/-)-trans 19. Interestingly, the enantiomer (-)-cis 18 displayed a preference for sigma1 receptor subtype whereas the (+)-cis 18 did for sigma2. These results prompt us to synthesize compounds with modification of nitrogen and carboxyl groups. The compounds obtained showed high affinities and selectivity for sigma sites. Moreover, modifications of carboxyl groups provided compounds with the highest affinities in the series. In particular, compound 25 with reverse-type ester showed a Ki of 0.6 and 4.05 nM for sigma1 and sigma2 binding sites, respectively.
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Affiliation(s)
- G Ronsisvalle
- Department of Pharmaceutical Sciences, University of Catania, Italy.
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16
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Nguyen VH, Mardon K, Kassiou M, Christie MD. In vitro and in vivo characterisation of [3H]ANSTO-14 binding to the sigma 1 binding sites. Nucl Med Biol 1999; 26:209-15. [PMID: 10100221 DOI: 10.1016/s0969-8051(98)00095-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
N-(4-phenylbutyl)-3-hydroxy-4-azahexacyclo[5.4.1.0(2,6).0(3, 10).0(5,9) .0(8,11)]dodecane (ANSTO-14) showed the highest activity for the sigma 1 site (Ki = 9.4 nM) and 19-fold sigma 1/sigma 2 selectivity. The present study showed that [3H]ANSTO-14 binds to a single high-affinity site in guinea pig brain membranes with an equilibrium Ki of 8.0 +/- 0.3 nM, in good agreement with the kinetic studies (Kd = 13.3 +/- 5.4 nM, n = 4), and a Bmax of 3.199 +/- 105 fmol/mg protein (n = 4). The in vivo biodistribution of [3H]ANSTO-14 showed a high uptake in the diencephalon. Pretreatment of rats with sigma ligands including (+)-pentazocine (sigma 1), ANSTO-14 (sigma 1), and DTG (sigma 1 and sigma 2) did not significantly reduce radiotracer uptake in the brain, but did in the spleen. A labelled metabolite was found in the liver and brain. Due to its insensitivity to sigma ligands, the accumulation of [3H]ANSTO-14 in the brain indicates high nonspecific binding. Therefore, [3H]ANSTO-14 is a suitable ligand for labelling sigma 1 sites in vitro but is not suitable for brain imaging of sigma binding sites in vivo.
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Affiliation(s)
- V H Nguyen
- Department of Pharmacology, The University of Sydney, NSW, Australia.
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17
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Ucar H, Cacciaguerra S, Spampinato S, Van derpoorten K, Isa M, Kanyonyo M, Poupaert JH. 2(3H)-benzoxazolone and 2(3H)-benzothiazolone derivatives: novel, potent and selective sigma1 receptor ligands. Eur J Pharmacol 1997; 335:267-73. [PMID: 9369382 DOI: 10.1016/s0014-2999(97)01248-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A series of original 2(3H)-benzoxazolone and 2(3H)-benzothiazolone derivatives were evaluated for their affinity at sigma1 and sigma2 receptor subtypes in competition binding experiments, using [3H](+)-pentazocine or [3H]1,3-di-o-tolyl-guanidine (DTG) in the presence of 100 nM (+)-N-allylnormetazocine (NANM) in guinea-pig brain membranes. Several of these derivatives showed preferential selectivity for sigma1 binding sites. Compound 1 [3-(1-piperidinoethyl)-6-propylbenzothiazolin-2-one] emerged as a potent sigma1 receptor ligand (Ki = 0.6 nM) and displayed a moderate selectivity over the sigma2 receptor subtype (Ki for sigma2/Ki for sigma1 = 29). Compounds 2 [3-(1-piperidinopropyl)-6-propanoylbenzothiazolin-2-one] and 3 [3-(1-piperidinopropyl)-6-propanoylbenzoxazolin-2-one] still showed rather high affinities for sigma1 binding sites with Ki values of 2.3 and 8.5 nM, respectively. On the contrary, they had 87- and 58-fold less affinity at sigma2 receptors, respectively. Unlike their potent affinity for sigma binding sites, these compounds had negligible affinity for mu-, delta- and kappa-opioid receptors, 5-HT2, dopamine D2, and muscarinic M2 receptors. Sigma receptor ligands may affect neuronal transmission and display, in animal models, antipsychotic, cognitive, motor, neuroprotective and anticonvulsant activity. Therefore, on the basis of these findings, these novel sigma receptor ligands were assayed, in mice, in three tests: maximal electroshock, subcutaneous pentylenetetrazol and rotarod neurotoxicity. Compound 1, administered intraperitoneally, was the most effective against maximal electroshock-induced seizures and was devoid of significant neurotoxic effects.
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Affiliation(s)
- H Ucar
- Unité de Chimie Pharmaceutique et de Radiopharmacie, Ecole de Pharmacie, Université catholique de Louvain, Brussels, Belgium.
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18
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Kamei H, Noda Y, Kameyama T, Nabeshima T. Role of (+)-SKF-10,047-sensitive sub-population of sigma 1 receptors in amelioration of conditioned fear stress in rats: association with mesolimbic dopaminergic systems. Eur J Pharmacol 1997; 319:165-72. [PMID: 9042587 DOI: 10.1016/s0014-2999(96)00851-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Rats exhibited a marked suppression of motility when they were re-placed in the same environment as that in which they had previously received an electric footshock. We examined the behavioral and neurochemical effects of (+)-N-allylnormetazocine hydrochloride ((+)-SKF-10,047) and (+)-pentazocine, putative sigma 1 receptor ligands, on this psychological-stress-induced motor suppression, defined as a conditioned fear stress. (+)-SKF-10,047 (3 and 6 mg/kg) dose-dependently attenuated the conditioned fear stress, whereas (+)-pentazocine failed to do so even at a higher dose (32 mg/kg). In rats showing the conditioned fear stress, dopamine turnover (i.e., the ratio of dopamine metabolites/dopamine contents) was decreased in the nucleus accumbens and was increased in the medial prefrontal cortex, but remained unchanged in the striatum. (+)-SKF-10,047 (3 and 6 mg/kg) dose-dependently reversed the decreased dopamine turnover in the nucleus accumbens without changing the increased dopamine turnover in the medial prefrontal cortex. (+)-Pentazocine (32 mg/kg) did not affect the stress-induced changes in dopamine turnover in these brain regions. Thus, the decreased dopamine turnover in the nucleus accumbens appears to be involved in the conditioned fear stress. These results suggest that (+)-SKF-10,047 ameliorates the conditioned fear stress by reversing the psychological stress-induced dysfunction in the mesolimbic dopaminergic systems, and that the (+)-SKF-10,047-sensitive sub-population of sigma 1 receptors may play in important role in this stress response.
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Affiliation(s)
- H Kamei
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan
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19
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DeHaven-Hudkins DL, Daubert JD, Sawutz DG, Tiberio L, Baine Y. [3H]1,3-di(2-tolyl) guanidine binds to a sigma 2 receptor on Jurkat cell membranes, but sigma compounds fail to influence immunomodulatory events in human peripheral blood lymphocytes. IMMUNOPHARMACOLOGY 1996; 35:27-39. [PMID: 8913792 DOI: 10.1016/0162-3109(96)00107-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The binding characteristics of the sigma ligand [3H]1.3-di(2-tolyl)guanidine (DTG) were investigated in membranes prepared from the Jurkat T cell line. Binding was saturable with a KD of 56 +/- 3 nM and a Bmax of 11706 +/- 3173 fmol/mg protein (n = 3). The rank order of potency for sigma reference compounds to inhibit binding in the Jurkat cell line was ifenprodil > 1,3-di(2-tolyl)guanidine > haloperidol > carbetapentane > (+)3-(3-hydroxyphenyl)-N-propylpiperidine ((+)3-PPP) > (-)pentazocine > caramiphen > (+)pentazocine, and significantly correlated with potency at sigma 2 binding sites in guinea pig brain (r = 0.90, p < 0.01). The immunomodulatory activities of the sigma ligands 1,3-di(2-tolyl)guanidine, haloperidol. (-)pentazocine and (+)pentazocine on CD3-induced proliferation, IL-2 production and Ca2+ flux in human lymphocytes did not reveal any consistent pharmacology that could be ascribed to potency of these compounds at sigma binding sites. Collectively the data demonstrate that the [3H]1,3-di(2-tolyl)guanidine binding site on Jurkat cell membranes has a pharmacology consistent with sigma receptors, but no modulation of functional activity or intracellular events in human peripheral blood lymphocytes correlating with sigma receptors was found.
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Affiliation(s)
- D L DeHaven-Hudkins
- Department of Biochemistry, Sterling Winthrop Pharmaceuticals Research Division, Collegeville, PA 19426, USA
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20
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Nguyen VH, Kassiou M, Johnston GA, Christie MJ. Comparison of binding parameters of sigma 1 and sigma 2 binding sites in rat and guinea pig brain membranes: novel subtype-selective trishomocubanes. Eur J Pharmacol 1996; 311:233-40. [PMID: 8891604 DOI: 10.1016/0014-2999(96)00395-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Comparisons of binding parameters of [3H](+)-pentazocine and [3H]1,3-di-o-tolylguanidine (DTG) at sigma binding sites in guinea pig and rat brain membranes demonstrated that [3H](+)-pentazocine binds to a single high-affinity site, whereas [3H]DTG binds to two high-affinity sites in both species. The Kd values of the radioligands were similar in both types of membranes. However, the density of sigma 1 sites in guinea pig was significantly higher than that of rat. Novel trishomocubanes were tested for their affinities at sigma 1 and sigma 2 binding sites in guinea pig brain membranes using [3H](+)-pentazocine and [3H]DTG as the radioligands. N-(4-Phenylbutyl)-3-hydroxy-4- azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecane (ANSTO-14) showed the highest affinity for the sigma 1 site (Ki = 9.4 nM) and 19-fold sigma 1/sigma 2 selectivity, as a result of increasing the alkyl chain between the cubane moiety and the aromatic ring. N-(3'-Fluorophenyl)methyl- 3-hydroxy-4-azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11]dodeca ne (ANSTO-19), displayed the highest affinity for sigma 2 sites (Ki = 19.6 nM) and 8-fold sigma 2/sigma 1 selectivity due to a fluoro substitution in the meta position of the aromatic ring. These represent structurally novel lead compounds, especially for the development of selective sigma 2 receptor ligands.
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Affiliation(s)
- V H Nguyen
- Department of Pharmacology, University of Sydney, NSW, Australia
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21
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Kamei H, Kameyama T, Nabeshima T. (+)-SKF-10,047 and dextromethorphan ameliorate conditioned fear stress via dopaminergic systems linked to phenytoin-regulated sigma 1 sites. Eur J Pharmacol 1996; 309:149-58. [PMID: 8874133 DOI: 10.1016/0014-2999(96)00346-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Mice exhibited a marked suppression of motility when they were re-placed in the same environment in which they had previously received an electric footshock. (+)-SKF-10,047 ([2S-(2 alpha, 6 alpha, 11R*)]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-me tha no-3-benzazocin-8-ol hydrochloride; (+)-N-allylnormetazocine hydrochloride) and dextromethorphan, putative sigma receptor agonists, have been reported to reserve this psychological stress-induced motor suppression, defined as conditioned fear stress, through phenytoin-regulated type sigma 1, receptors. In the present study, we investigated the involvement of dopaminergic neurons in the ameliorating effects of (+)-SKF-10,047 and dextromethorphan on conditioned fear stress. (+)-SKF-10,047 and dextromethorphan attenuated conditioned fear stress at low doses (4 and 20 mg/kg, respectively) when they were co-administered with phenytoin (10 mg/kg), an anticonvulsant drug. The effects were antagonized by the sigma receptor antagonists. NE-100 (N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]-ethylamine monohydrochloride) and BMY-14802 (a-(4-fluoro-phenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine-butanol hydrochloride). Furthermore, the effects of (+)-SKF-10,047 or dextromethorphan in combination with phenytoin were blocked by the dopamine D1 receptor antagonist. SCH 23390 (R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine), and the dopamine D2 receptor antagonist, (-)-sulpiride, and they were also attenuated by 6-hydroxydopamine-induced lesions of dopaminergic neurons. The ameliorating effects of (+)-SKF-10,047 and dextromethorphan on conditioned fear stress at high doses (5 and 30 mg/kg, respectively) were also blocked by both the dopamine receptor antagonists. These results suggest that the stress-induced motor suppression is restored by the activation of dopaminergic neuronal systems as a result of the stimulation of phenytoin-regulated type sigma 1 receptors.
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Affiliation(s)
- H Kamei
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan
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22
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Kamei H, Kameyama T, Nabeshima T. (+)-SKF-10,047 and dextromethorphan ameliorate conditioned fear stress through the activation of phenytoin-regulated sigma 1 sites. Eur J Pharmacol 1996; 299:21-8. [PMID: 8901003 DOI: 10.1016/0014-2999(95)00830-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Mice exhibited a marked suppression of motility when they were replaced in the same environment in which they had previously received an electric footshock. This psychological stress-induced motor suppression, known as conditioned fear stress, was dose dependently attenuated by (+)-N-allylnormetazocine ((+)-SKF-10,047) and by dextromethorphan, putative sigma receptor agonists, but not by other sigma receptor ligands, (+)-pentazocine and 1,3-di-(2-tolyl)guanidine (DTG). Unlike (+)-SKF-10,047 and dextromethorphan, the non-competitive NMDA receptor antagonists, phencyclidine and dizocilpine, attenuated the conditioned fear stress only at high doses that induced marked hypermotility in non-stressed mice. The effects of (+)-SKF-10,047 and dextromethorphan, but not phencyclidine and dizocilpine, on the conditioned fear stress were antagonized by the sigma receptor antagonists, NE-100 (N,N-dipropyl-2-[4-methoxy-3-(2- phenylethoxy)phenyl]-ethylamine monohydrochloride) and BMY-14802 (alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine- butanol hydrochloride). Interestingly, the effects of (+)-SKF-10,047 and dextromethorphan on the stress response were enhanced by combination with phenytoin, an anticonvulsant drug, whereas those of (+)- pentazocine, DTG, phencyclidine, and dizocilpine were not. These results suggest that activation of phenytoin-regulated type sigma 1 receptors, but not of phencyclidine receptors, is involved in the ameliorating effects of (+)-SKF-10,047 and dextromethorphan on stress-induced motor suppression.
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Affiliation(s)
- H Kamei
- Department of Chemical Pharmacology, Meijo University, Nagoya, Japan
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23
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Gonzalez-Alvear GM, Werling LL. sigma1 Receptors in rat striatum regulate NMDA-stimulated [3H]dopamine release via a presynaptic mechanism. Eur J Pharmacol 1995; 294:713-9. [PMID: 8750737 DOI: 10.1016/0014-2999(95)00617-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The role of the sigma1 receptor in the regulation of N-methyl-D-aspartate (NMDA)-stimulated [3H]dopamine release from rat striatal slices was examined. The sigma receptor agonist 1S,2R-(--)-N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)cy clohexylamine (BD737) inhibited stimulated release in a concentration-dependent manner. The sigma1 receptor antagonist, 1-(cyclopropylmethyl)-4-(2'-(4"-fluorophenyl)-2'-oxoethyl)piperidi ne HBr (DuP 734), reversed inhibition of release by BD737. Haloperidol, di-o-tolylguanidine (DTG) and N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine (BD1008) reversed the BD737-mediated inhibition of release. Haloperidol and DTG also antagonized inhibition of stimulated release by (+)-pentazocine. Furthermore, BD737 and (+)-pentazocine inhibited stimulated release in the presence of tetrodotoxin, suggesting that sigma1 receptors regulating dopamine release are located on dopaminergic nerve terminals. These data suggest that sigma1 receptors may be important in the regulation of glutamate-stimulated dopamine release.
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Affiliation(s)
- G M Gonzalez-Alvear
- Department of Pharmacology, The George Washington University Medical Center, Washington DC 20037, USA
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24
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Abstract
In mice, activation of sigma1 receptors antagonizes opioid analgesia. Sigma antagonists potentiate opioid analgesia, implying that the anti-opioid sigma system is tonically active. Co-administration of haloperidol with the mu opioid morphine, the kappa 1 analgesic U50,488H or the kappa 3 agonist naloxone benzoylhydrazone enhances the analgesic activity of all agents. The effect results from sigma receptor blockade since (-)sulpiride, a selective D2 antagonist which does not block sigma receptors, is inactive.
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Affiliation(s)
- C C Chien
- Cotzias Laboratory of Neuro-Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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25
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DeHaven-Hudkins DL, Allen JT, Hudkins RL, Stubbins JF, Tortella FC. Anticonvulsant activity of caramiphen analogs. Life Sci 1995; 56:1571-6. [PMID: 7723585 DOI: 10.1016/0024-3205(95)00123-n] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Caramiphen potently blocks maximal electroshock (MES)-induced seizures in mice and rats. The anticonvulsant mechanism has been hypothesized to be due to high-affinity binding to sigma recognition sites in brain. To study the structure-activity relationship for anticonvulsant activity of caramiphen we evaluated 8 analogs in MES-induced seizures in rats and also determined whether a correlation exists between anticonvulsant potency and sigma binding affinity. Some of the analogs potently inhibited sigma binding but were devoid of anticonvulsant activity. Aminocaramiphen 2 (ED50 = 3.4 mg/kg) and N-methyl-4-piperidinyl 1-phenylcyclopentanecarboxylate 9 (ED50 = 4.8 mg/kg) showed anticonvulsant activity comparable to caramiphen (ED50 = 3.1 mg/kg), although in sigma binding assays the affinities were 3-and 30-fold less than caramiphen, respectively. In the presence of 250 microM of phenytoin, caramiphen and p-aminocaramiphen showed 3- to 5-fold increases in affinity for [3H](+)pentazocine binding, whereas piodocaramiphen, which was inactive as an anticonvulsant, showed no change in affinity for sigma binding. These results indicate that anticonvulsant activity of the caramiphen analogs is not due to interaction with sigma binding sites.
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Affiliation(s)
- D L DeHaven-Hudkins
- Department of Biochemistry, Sterling Winthrop Pharmaceuticals Research Division, Collegeville, PA 19426, USA
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26
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Hudkins RL, Mailman RB, DeHaven-Hudkins DL. RLH-033, a novel, potent and selective ligand for the sigma 1 recognition site. Eur J Pharmacol 1994; 271:235-6. [PMID: 7698207 DOI: 10.1016/0014-2999(94)90286-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
RLH-033 [2-(4-phenylpiperidinyl)ethyl 1-(4-nitrophenyl)cyclopentanecarboxylate HCl] is a rationally designed ligand that was synthesized and evaluated for its binding affinities at sigma 1 and sigma 2 sites in guinea pig brain. RLH-033 has high affinity (Ki = 50 pM) for sigma 1 sites labeled by [3H](+)-pentazocine, while it was over 2000-fold less affinity at sigma 2 sites labeled by [3H]1,3-di(2-tolyl)guanidine (DTG) in the presence of 500 nM (+)-pentazocine (Ki = 105 nM). Unlike its potent sigma activity, the compound has little affinity for dopamine D1 (Ki = 2.9 microM), D2 (Ki = 0.35 microM), muscarinic M1 (Ki = 0.88 microM) or M2 (Ki = 1.7 microM) receptors, and none at all for N-methyl-D-aspartate, phencyclidine and opioid receptors. Thus, RLH-033 is the most potent sigma 1 ligand reported to date, and its very high affinity suggests it may be a useful radioligand to characterize the pharmacology of sigma 1 recognition sites.
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27
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28
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Paul R, Lavastre S, Floutard D, Floutard R, Canat X, Casellas P, Le Fur G, Brelière JC. Allosteric modulation of peripheral sigma binding sites by a new selective ligand: SR 31747. J Neuroimmunol 1994; 52:183-92. [PMID: 7794416 DOI: 10.1016/0165-5728(94)90112-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The interactions of a new compound SR 31747 with sigma sites were examined in rat spleen membranes and in human peripheral blood leukocytes (PBL). Nanomolar concentrations of SR 31747 selectively inhibited in a non-competitive manner the binding of the prototypic sigma ligands [3H](+)-pentazocine, [3H](+)-3PPP and [3H]DTG on rat spleen membranes. Characterization of SR 31747 binding sites using [3H]SR 31747 as a ligand showed that this compound binds reversibly, with high affinity to one class of sites on rat spleen membranes (Kd 0.66 nM, Bmax 5646 fmol/mg protein). The pharmacological profile of [3H]SR 31747 binding sites was consistent with the presence of specific sites distinct from classical sigma 1 and sigma 2 receptor subtypes strongly suggesting an allosteric modulation of sigma sites by SR 31747. Similarly, [3H]SR 31747 binding sites were demonstrated on human PBL and also on purified subpopulations of human mononuclear cells (granulocytes, NK cells, T4, T8 and B lymphocytes). Administered to mice by i.p. or oral route 30 min before sacrifice, SR 31747 strongly inhibited the binding of [3H](+)-3PPP to mice spleen membranes with ED50 values of 0.18 and 1.43 mg/kg, respectively. Taken together these results could suggest a potential immunological activity of SR 31747 either directly or through allosteric modulation of peripheral sigma sites.
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Affiliation(s)
- R Paul
- Sanofi Recherche, Montpellier, France
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DeHaven-Hudkins DL, Lanyon LF, Ford-Rice FY, Ator MA. sigma recognition sites in brain and peripheral tissues. Characterization and effects of cytochrome P450 inhibitors. Biochem Pharmacol 1994; 47:1231-9. [PMID: 8161352 DOI: 10.1016/0006-2952(94)90395-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Binding to sigma sites in subcellular fractions of brain and in crude homogenates from peripheral tissues of the guinea pig was characterized with the [3H]ligands (+)pentazocine and di(2-tolyl)guanidine (DTG). The inhibitory effects of representative sigma compounds and cytochrome P450 inhibitors were evaluated in guinea pig tissues, and the effects of cytochrome P450 induction on sigma binding in the rat were investigated. For both ligands, the majority of sites were localized to the microsomal fractions. The KD values for [3H](+)pentazocine- or [3H]DTG-labeled sigma sites in guinea pig liver and testes were 2-fold lower than those in brain and heart. The number of sites labeled by [3H](+)pentazocine varied, with an order of liver > testes > brain > heart. In contrast, the Bmax values for [3H]DTG-defined sigma sites were greatest in testes, followed by liver, brain and heart. The rank order of potency for representative sigma and P450 compounds was similar in brain, liver and testes for both [3H]ligands, and the potency of selective compounds to displace sigma binding in guinea pig liver failed to correlate with their abilities to inhibit cytochrome P450IID1 activity in human liver. Following induction of cytochrome P450IIB1 with phenobarbital or cytochrome P450IA1 with beta-naphthoflavone, neither the affinity nor the number of sigma sites was altered in rat brain or liver. These results suggest that sigma sites in the periphery are similar to those in the brain, and that the sigma binding site is not identical with cytochrome P450IIB1, P450IA1 or P450IID1.
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Affiliation(s)
- D L DeHaven-Hudkins
- Department of Enzymology and Receptor Biochemistry, Sterling Winthrop Pharmaceuticals Research Division, Collegeville, PA 19426-0900
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