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Santos EJ, Akbarali HI, Bow EW, Chambers DR, Gutman ES, Jacobson AE, Kang M, Lee YK, Lutz JA, Rice KC, Sulima A, Negus SS. Low-Efficacy Mu Opioid Agonists as Candidate Analgesics: Effects of Novel C-9 Substituted Phenylmorphans on Pain-Depressed Behavior in Mice. J Pharmacol Exp Ther 2024:JPET-AR-2024-002153. [PMID: 38637015 DOI: 10.1124/jpet.124.002153] [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] [Received: 02/06/2024] [Revised: 03/11/2024] [Accepted: 03/27/2024] [Indexed: 04/20/2024] Open
Abstract
Low efficacy mu opioid receptor (MOR) agonists may serve as novel candidate analgesics with improved safety relative to high-efficacy opioids. This study used a recently validated assay of pain-depressed behavior in mice to evaluate a novel series of MOR-selective C9-substituted phenylmorphan opioids with graded MOR efficacies. Intraperitoneal injection of dilute lactic acid (IP acid) served as a noxious stimulus to depress locomotor activity by mice in an activity chamber composed of two compartments connected by an obstructed door. Behavioral measures included (1) crosses between compartments (vertical activity over the obstruction) and (2) movement counts quantified as photobeam breaks summed across compartments (horizontal activity). Each drug was tested alone and as a pretreatment to IP acid. A charcoal-meal test and whole-body-plethysmography assessment of breathing in 5% CO2 were also used to assess gastrointestinal (GI) inhibition and respiratory depression, respectively. IP acid produced a concentration-dependent depression in crosses and movement that was optimally alleviated by intermediate- to low-efficacy phenylmorphans with sufficient efficacy to produce analgesia with minimal locomotor disruption. Follow-up studies with two low-efficacy phenylmorphans (JL-2-39 and DC-1-76.1) indicated that both drugs produced naltrexone-reversible antinociception with a rapid onset and a duration of ~1hr. Potency of both drugs increased when behavior was depressed by a lower IP-acid concentration, and neither drug alleviated behavioral depression by a non-pain stimulus (IP lithium chloride). Both drugs produced weaker GI inhibition and respiratory depression than fentanyl and attenuated fentanyl-induced GI inhibition and respiratory depression. Results support further consideration of selective, low-efficacy MOR agonists as candidate analgesics. Significance Statement This study used a novel set of mu opioid receptor (MOR)-selective opioids with graded MOR efficacies to examine the lower boundary of MOR efficacy sufficient to relieve pain-related behavioral depression in mice. Two novel low-efficacy opioids (JL-2-39, DC-1-76.1) produced effective antinociception with improved safety relative to higher- or lower-efficacy opioids, and results support further consideration of these and other low-efficacy opioids as candidate analgesics.
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Affiliation(s)
- Edna J Santos
- Pharmacology & Toxicology, Virginia Commonwealth University, United States
| | - Hamid I Akbarali
- Pharmacology and Toxicology, Virginia Commonwealth University, United States
| | | | | | | | | | - Minho Kang
- Pharm & Tox, Virginia Commonwealth University, United States
| | - Young K Lee
- Pharmacology and Toxicology, Virginia Commonwealth University, United States
| | | | | | - Agnieszka Sulima
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, United States
| | - S Stevens Negus
- Pharmacology and Toxicology, Virginia Commonwealth University, United States
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Santos EJ, Nassehi N, Bow EW, Chambers DR, Gutman ES, Jacobson AE, Lutz JA, Marsh SA, Rice KC, Sulima A, Selley DE, Negus SS. Role of efficacy as a determinant of locomotor activation by mu-opioid receptor (MOR) ligands in female and male mice. II. Effects of novel MOR-selective phenylmorphans with high-to-low MOR efficacy. Pharmacol Res Perspect 2023; 11:e01111. [PMID: 37381112 DOI: 10.1002/prp2.1111] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 06/05/2023] [Indexed: 06/30/2023] Open
Abstract
Low-efficacy mu-opioid receptor (MOR) agonists represent promising therapeutics, but existing compounds (e.g., buprenorphine, nalbuphine) span a limited range of low MOR efficacies and have poor MOR selectivity. Accordingly, new and selective low-efficacy MOR agonists are of interest. A novel set of chiral C9-substituted phenylmorphans has been reported to display improved MOR selectivity and a range of high-to-low MOR efficacies under other conditions; however, a full opioid receptor binding profile for these drugs has not been described. Additionally, studies in mice will be useful for preclinical characterization of these novel compounds, but the pharmacology of these drugs in mice has also not been examined. Accordingly, the present study characterized the binding selectivity and in vitro efficacy of these compounds using assays of opioid receptor binding and ligand-stimulated [35 S]GTPɣS binding. Additionally, locomotor effects were evaluated as a first step for in vivo behavioral assessment in mice. The high-efficacy MOR agonist and clinically effective antidepressant tianeptine was included as a comparator. In binding studies, all phenylmorphans showed improved MOR selectivity relative to existing lower-efficacy MOR agonists. In the ligand-stimulated [35 S]GTPɣS binding assay, seven phenylmorphans had graded levels of sub-buprenorphine MOR efficacy. In locomotor studies, the compounds again showed graded efficacy with a rapid onset and ≥1 h duration of effects, evidence for MOR mediation, and minor sex differences. Tianeptine functioned as a high-efficacy MOR agonist. Overall, these in vitro and in vivo studies support the characterization of these compounds as MOR-selective ligands with graded MOR efficacy and utility for further behavioral studies in mice.
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Affiliation(s)
- Edna J Santos
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Nima Nassehi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Eric W Bow
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Dana R Chambers
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Eugene S Gutman
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Arthur E Jacobson
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Joshua A Lutz
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Samuel A Marsh
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Kenner C Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Agnieszka Sulima
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, NIDA and NIAAA, Bethesda, Maryland, USA
| | - Dana E Selley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
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Chambers DR, Sulima A, Luo D, Prisinzano TE, Jacobson AE, Rice KC. A MOR Antagonist with High Potency and Antagonist Efficacy among Diastereomeric C9-Alkyl-Substituted N-Phenethyl-5-(3-hydroxy)phenylmorphans. Molecules 2023; 28:5411. [PMID: 37513283 PMCID: PMC10386414 DOI: 10.3390/molecules28145411] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/05/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
The 5-(3-hydroxy)phenylmorphan structural class of compounds are unlike the classical morphinans, 4,5-epoxymorphinans, and 6,7-benzomorphans, in that they have an equatorially oriented aromatic ring rather than the axial orientation of that ring found in the classical opioids. This modified and simplified opioid-like structure has been shown to retain antinociceptive activity, depending on its stereochemistry and substituents, and some of them have been found to be much more potent than morphine. A simple C9-hydroxy-5-(3-hydroxy)phenylmorphan enantiomer was found to be about 500 times more potent than morphine in vivo. We have previously examined C9-alkenyl and hydroxyalkyl substituents in the N-phenethyl-5-(3-hydroxy)phenylmorphan class of compounds. Comparable C9-alkyl (methyl through butyl) substituents, with their sets of diastereomers, have not been explored. All these compounds have now been synthesized to determine the effect chain-length and stereochemistry at the C9 position in the molecule might have on their interaction with opioid receptors. We now report the synthesis and in vitro activity of 16 compounds, the C9-methyl, ethyl, propyl, and butyl diastereomers, using the inhibition of forskolin-induced cAMP accumulation assay. Several potent (sub-nanomolar and nanomolar) MOR compounds were found to be selective agonists with varying efficacy. Of greatest interest, a selective MOR antagonist was discovered; it did not display any DOR or KOR agonist activity in vitro, was three times more potent than naltrexone, and was found to antagonize the EC90 of fentanyl at MOR to a greater extent than naltrexone.
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Affiliation(s)
- Dana R Chambers
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Department of Health and Human Services, 9800 Medical Center Drive, Bethesda, MD 20892, USA
| | - Agnieszka Sulima
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Department of Health and Human Services, 9800 Medical Center Drive, Bethesda, MD 20892, USA
| | - Dan Luo
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 S. Limestone Street, Lexington, KY 40536, USA
| | - Thomas E Prisinzano
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 S. Limestone Street, Lexington, KY 40536, USA
| | - Arthur E Jacobson
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Department of Health and Human Services, 9800 Medical Center Drive, Bethesda, MD 20892, USA
| | - Kenner C Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Department of Health and Human Services, 9800 Medical Center Drive, Bethesda, MD 20892, USA
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Affiliation(s)
- Dana R. Chambers
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - Antoine Juneau
- Département de Chimie, Université du Québec à Montréal, Case Postale
8888, Succursale Centre-Ville, Montréal, Quebec H3C 3P8, Canada
| | - Cory T. Ludwig
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - Mathieu Frenette
- Département de Chimie, Université du Québec à Montréal, Case Postale
8888, Succursale Centre-Ville, Montréal, Quebec H3C 3P8, Canada
| | - David B. C. Martin
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
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Affiliation(s)
- Dana R. Chambers
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - Raymond E. Sullivan
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - David B. C. Martin
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
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Deans RM, Taniguchi M, Chandrashaker V, Ptaszek M, Chambers DR, Soares ARM, Lindsey JS. Complexity in structure-directed prebiotic chemistry. Unexpected compositional richness from competing reactants in tetrapyrrole formation. NEW J CHEM 2016. [DOI: 10.1039/c6nj00543h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acyclic reactants afford “partially defective” pyrroles that interfere with chain growth of “normal” pyrroles on the path to tetrapyrrole macrocycles.
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Affiliation(s)
- Richard M. Deans
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
| | | | | | - Marcin Ptaszek
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
| | - Dana R. Chambers
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
| | - Ana R. M. Soares
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
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Bowker TJ, Wood DA, Davies MJ, Sheppard MN, Cary NRB, Burton JDK, Chambers DR, Dawling S, Hobson HL, Pyke SDM, Riemersma RA, Thompson SG. Sudden, unexpected cardiac or unexplained death in England: a national survey. QJM 2003; 96:269-79. [PMID: 12651971 DOI: 10.1093/qjmed/hcg038] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Post-mortem examinations of adults who were apparently healthy but died suddenly and unexpectedly sometimes reveal no morphological abnormalities to explain their deaths. The frequency of such unexplained deaths in relation to other causes of sudden cardiac death is not known. AIM To estimate the frequency of sudden unexpected cardiac or unexplained death in England. DESIGN Prospective survey using a stratified random sample of 83 of the 132 H.M. Coroner's jurisdictions in England. METHODS Consecutive White Caucasians, aged 16-64 years, with no medical history of cardiac disease, seen alive within 12 h of death, on whom autopsy found either a cardiac or no identifiable cause of death, were included. The coroner's officer sent a copy of the post-mortem report and a completed case registration form to the investigators, with tissue samples. RESULTS Sixty-seven (81%) coroners participated, each maintaining prospective surveillance for 4 months. Of 692 ascertained cases, case registration forms were received for 650 (94%), post-mortem reports for 682 (99%), blood samples for 569 (82%), myocardial slices for 517 (75%) and whole hearts for 47 (7%). In cases with myocardial tissue, death was ascribed to ischaemic heart disease in 465 (82.4%). In 43.1% the ischaemia was acute, in 19.1% there was myocardial scarring but no acute ischaemia, and 20.2% had coronary atheroma only. Death was due to left ventricular hypertrophy in 32 (5.7%), to other cardiac causes in 30 (5.3%) and in 23 (4.1%) there was no clear cause. Those with cardiac causes were 81% male, median ages 55.9 (male) and 56.6 (female) years. The 23 unexplained deaths were 57% female, median ages 40.5 (male) and 54.9 (female) years. The estimated annual frequency of sudden unexpected death due to cardiac or unidentified causes, in English adults of employment age, was 11/100,000 (3481 annual deaths). DISCUSSION In 4.1% of sudden unexpected deaths under 65 years, no cause was found. Until it becomes accepted practice to identify these cases by a name, such as Sudden Adult Death Syndrome (SADS), it will not be possible to study their aetiology systematically.
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Affiliation(s)
- T J Bowker
- Clinical Epidemiology, The Royal Brompton and Harefield Campus, National Heart & Lung Institute, Imperial College School of Medicine, University of London.
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Chambers DR, Procter J, Muratova O, Byrne K, Keister D, Shanks D, Magill A, Stroncek D. In vitro RBC exposure to Plasmodium falciparum has no effect on RBC antigen expression. Transfus Med 2002; 12:213-9. [PMID: 12071878 DOI: 10.1046/j.1365-3148.2002.00375.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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: 11/20/2022]
Abstract
Severe malarial anaemia is a leading cause of death in African children younger than 3 years of age who are infected with Plasmodium falciparum. The pathogenesis of this anaemia is not understood. The purpose of this study was to determine if P. falciparum induces changes in RBC membranes that contribute to the immune destruction of RBCs. RBCs were collected from healthy subjects and tested using standard haemagglutination assays for 45 antigens representing 21 blood group systems/collections before and after exposure to P. falciparum, strain FVO. Lectins were used to determine whether crypt or neoantigens were expressed on the RBC membrane. Polybrene was used to detect changes in sialic acid. RBCs were cultured in vitro with and without the parasite, and blinded serologic studies were completed. CD35 (complement receptor 1), CD55 (decay-accelerating factor), CD59 (membrane inhibitor of reactive lysis) and CD47 (integrin-associated protein) flow cytometric assays were compared for infected and uninfected RBCs. The percentage of parasitaemia was determined using Giemsa-stained thin blood films. Two (Ch, Lub) of the 45 antigens had differing strengths of agglutination between infected and uninfected RBCs, but these differences were resolved with a second source of antisera. Forty-three antigens showed no significant differences in the strength of agglutination between the infected and uninfected RBCs. Lectin and polybrene testing showed no differences. CD35, CD55, CD59 and CD47 levels showed no significant differences. P. falciparum does not appear to alter the expression of classified immunogenic antigens on the RBC membrane in this in vitro system. The pathogenesis of the haemolytic episode that occurs in these children remains unclear.
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Affiliation(s)
- D R Chambers
- Department of Transfusion Medicine, Warren G. Magnuson Clinical Center, National Institute of Allergy and Infectious Diseases/NIH, Building 10, Room 1C711, 120 Center Drive, Bethesda, MD 20892, USA
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Chambers DR. A controversial inquest. Med Sci Law 1995; 35:185-186. [PMID: 7651093 DOI: 10.1177/002580249503500301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Chambers DR. Publicity and self-destruction. Med Sci Law 1994; 34:93-94. [PMID: 8028496 DOI: 10.1177/002580249403400201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Abstract
Serotonergic mechanisms have been investigated in postmortem brain samples from controls and suicide victims. The concentrations of 5-hydroxytryptamine (serotonin; 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were determined in occipital cortex and hippocampus and the high-affinity binding of ligands to the 5-HT1, 5-HT2 and imipramine-binding sites was assessed in frontal cortex, occipital cortex and hippocampus. The only significant difference between the two groups was a modest increase in 5-HIAA levels in the hippocampus of suicide victims. There was no evidence to suggest that those suicide victims with a clinical history of depression represented a subgroup with altered metabolite levels or binding values. The storage conditions of the samples were not related to the metabolite levels or binding values. There was, however, a significant positive correlation between [3H]imipramine binding and age in some brain regions. The results do not provide any evidence of gross alterations in 5-HT mechanisms in suicide or depression.
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Chambers DR. Ethics or medical ethics. Med Sci Law 1984; 24:17-25. [PMID: 6700397 DOI: 10.1177/002580248402400104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Chambers DR. The Inner North London Study into sudden death in infants--the role of the coroner. Med Sci Law 1981; 21:121-122. [PMID: 7231075 DOI: 10.1177/002580248102100209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Chambers DR. Accidental Death in Hospital. Med Chir Trans 1980; 73:87-9. [PMID: 7230195 PMCID: PMC1437312 DOI: 10.1177/014107688007300202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Chambers DR. Sudden and unexpected death in infancy. Health Visit 1973; 46:334-5. [PMID: 4493151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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