1
|
Hou L, Rong J, Haider A, Ogasawara D, Varlow C, Schafroth MA, Mu L, Gan J, Xu H, Fowler CJ, Zhang MR, Vasdev N, Ametamey S, Cravatt BF, Wang L, Liang SH. Positron Emission Tomography Imaging of the Endocannabinoid System: Opportunities and Challenges in Radiotracer Development. J Med Chem 2020; 64:123-149. [PMID: 33379862 DOI: 10.1021/acs.jmedchem.0c01459] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The endocannabinoid system (ECS) is involved in a wide range of biological functions and comprises cannabinoid receptors and enzymes responsible for endocannabinoid synthesis and degradation. Over the past 2 decades, significant advances toward developing drugs and positron emission tomography (PET) tracers targeting different components of the ECS have been made. Herein, we summarized the recent development of PET tracers for imaging cannabinoid receptors 1 (CB1R) and 2 (CB2R) as well as the key enzymes monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), particularly focusing on PET neuroimaging applications. State-of-the-art PET tracers for the ECS will be reviewed including their chemical design, pharmacological properties, radiolabeling, as well as preclinical and human PET imaging. In addition, this review addresses the current challenges for ECS PET biomarker development and highlights the important role of PET ligands to study disease pathophysiology as well as to facilitate drug discovery.
Collapse
Affiliation(s)
- Lu Hou
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Daisuke Ogasawara
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, SR107, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Department of Psychiatry/Institute of Medical Science, University of Toronto, 250 College Street, Toronto, M5T 1R8 ON, Canada
| | - Michael A Schafroth
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, SR107, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Linjing Mu
- Center for Radiopharmaceutical Sciences of ETH, PSI, and USZ, and Institute of Pharmaceutical Sciences, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Jiefeng Gan
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Hao Xu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Christopher J Fowler
- Department of Pharmacology and Clinical Neuroscience, Umeå University, SE-901 87 Umeå, Sweden
| | - Ming-Rong Zhang
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States.,Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Department of Psychiatry/Institute of Medical Science, University of Toronto, 250 College Street, Toronto, M5T 1R8 ON, Canada
| | - Simon Ametamey
- Center for Radiopharmaceutical Sciences of ETH, PSI, and USZ, and Institute of Pharmaceutical Sciences, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Benjamin F Cravatt
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, SR107, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lu Wang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China.,Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| |
Collapse
|
2
|
Vlot AHC, de Witte WEA, Danhof M, van der Graaf PH, van Westen GJP, de Lange ECM. Target and Tissue Selectivity Prediction by Integrated Mechanistic Pharmacokinetic-Target Binding and Quantitative Structure Activity Modeling. AAPS JOURNAL 2017; 20:11. [PMID: 29204742 DOI: 10.1208/s12248-017-0172-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/20/2017] [Indexed: 12/31/2022]
Abstract
Selectivity is an important attribute of effective and safe drugs, and prediction of in vivo target and tissue selectivity would likely improve drug development success rates. However, a lack of understanding of the underlying (pharmacological) mechanisms and availability of directly applicable predictive methods complicates the prediction of selectivity. We explore the value of combining physiologically based pharmacokinetic (PBPK) modeling with quantitative structure-activity relationship (QSAR) modeling to predict the influence of the target dissociation constant (K D) and the target dissociation rate constant on target and tissue selectivity. The K D values of CB1 ligands in the ChEMBL database are predicted by QSAR random forest (RF) modeling for the CB1 receptor and known off-targets (TRPV1, mGlu5, 5-HT1a). Of these CB1 ligands, rimonabant, CP-55940, and Δ8-tetrahydrocanabinol, one of the active ingredients of cannabis, were selected for simulations of target occupancy for CB1, TRPV1, mGlu5, and 5-HT1a in three brain regions, to illustrate the principles of the combined PBPK-QSAR modeling. Our combined PBPK and target binding modeling demonstrated that the optimal values of the K D and k off for target and tissue selectivity were dependent on target concentration and tissue distribution kinetics. Interestingly, if the target concentration is high and the perfusion of the target site is low, the optimal K D value is often not the lowest K D value, suggesting that optimization towards high drug-target affinity can decrease the benefit-risk ratio. The presented integrative structure-pharmacokinetic-pharmacodynamic modeling provides an improved understanding of tissue and target selectivity.
Collapse
Affiliation(s)
- Anna H C Vlot
- Division of Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands
| | - Wilhelmus E A de Witte
- Division of Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands
| | - Meindert Danhof
- Division of Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands
| | - Piet H van der Graaf
- Division of Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands.,Certara Quantitative Systems Pharmacology, Canterbury Innovation Centre, Canterbury, CT2 7FG, UK
| | - Gerard J P van Westen
- Division of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands
| | - Elizabeth C M de Lange
- Division of Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333, CC, Leiden, The Netherlands.
| |
Collapse
|
3
|
Xia L, de Vries H, Lenselink EB, Louvel J, Waring MJ, Cheng L, Pahlén S, Petersson MJ, Schell P, Olsson RI, Heitman LH, Sheppard RJ, IJzerman AP. Structure-Affinity Relationships and Structure-Kinetic Relationships of 1,2-Diarylimidazol-4-carboxamide Derivatives as Human Cannabinoid 1 Receptor Antagonists. J Med Chem 2017; 60:9545-9564. [PMID: 29111736 PMCID: PMC5734604 DOI: 10.1021/acs.jmedchem.7b00861] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
We
report on the synthesis and biological evaluation of a series of 1,2-diarylimidazol-4-carboxamide
derivatives developed as CB1 receptor antagonists. These
were evaluated in a radioligand displacement binding assay, a [35S]GTPγS binding assay, and in a competition association
assay that enables the relatively fast kinetic screening of multiple
compounds. The compounds show high affinities and a diverse range
of kinetic profiles at the CB1 receptor and their structure–kinetic
relationships (SKRs) were established. Using the recently resolved
hCB1 receptor crystal structures, we also performed a modeling
study that sheds light on the crucial interactions for both the affinity
and dissociation kinetics of this family of ligands. We provide evidence
that, next to affinity, additional knowledge of binding kinetics is
useful for selecting new hCB1 receptor antagonists in the
early phases of drug discovery.
Collapse
Affiliation(s)
- Lizi Xia
- Division of Medicinal Chemistry, LACDR, Leiden University , 2300RA Leiden, The Netherlands
| | - Henk de Vries
- Division of Medicinal Chemistry, LACDR, Leiden University , 2300RA Leiden, The Netherlands
| | - Eelke B Lenselink
- Division of Medicinal Chemistry, LACDR, Leiden University , 2300RA Leiden, The Netherlands
| | - Julien Louvel
- Division of Medicinal Chemistry, LACDR, Leiden University , 2300RA Leiden, The Netherlands
| | | | | | - Sara Pahlén
- Medicinal Chemistry, Cardiovascular and Metabolic Diseases, IMED Biotech Unit, AstraZeneca , Gothenburg SE-431 83, Sweden
| | - Maria J Petersson
- Medicinal Chemistry, Cardiovascular and Metabolic Diseases, IMED Biotech Unit, AstraZeneca , Gothenburg SE-431 83, Sweden
| | | | | | - Laura H Heitman
- Division of Medicinal Chemistry, LACDR, Leiden University , 2300RA Leiden, The Netherlands
| | - Robert J Sheppard
- Medicinal Chemistry, Oncology, IMED Biotech Unit, AstraZeneca , Cambridge SK10 2NA, United Kingdom
| | - Adriaan P IJzerman
- Division of Medicinal Chemistry, LACDR, Leiden University , 2300RA Leiden, The Netherlands
| |
Collapse
|
4
|
Khajehali E, Malone DT, Glass M, Sexton PM, Christopoulos A, Leach K. Biased Agonism and Biased Allosteric Modulation at the CB1 Cannabinoid Receptor. Mol Pharmacol 2015; 88:368-79. [PMID: 26044547 DOI: 10.1124/mol.115.099192] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/04/2015] [Indexed: 12/12/2022] Open
Abstract
CB1 cannabinoid receptors (CB1Rs) are attractive therapeutic targets for numerous central nervous system disorders. However, clinical application of cannabinoid ligands has been hampered owing to their adverse on-target effects. Ligand-biased signaling from, and allosteric modulation of, CB1Rs offer pharmacological approaches that may enable the development of improved CB1R drugs, through modulation of only therapeutically desirable CB1R signaling pathways. There is growing evidence that CB1Rs are subject to ligand-biased signaling and allosterism. Therefore, in the present study, we quantified ligand-biased signaling and allosteric modulation at CB1Rs. Cannabinoid agonists displayed distinct biased signaling profiles at CB1Rs. For instance, whereas 2-arachidonylglycerol and WIN55,212-2 [(R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-napthalenylmethanone] showed little preference for inhibition of cAMP and phosphorylation of extracellular signal-regulated kinase 1/2 (pERK1/2), N-arachidonoylethanolamine (anandamide), methanandamide, CP55940 [2-[(1R,2R,5R)-5-hydroxy-2-(3-hydroxypropyl)cyclohexyl]-5-(2-methyloctan-2-yl)phenol], and HU-210 [11-hydroxy-Δ(8)-THC-dimethylheptyl] were biased toward cAMP inhibition. The small-molecule allosteric modulator Org27569 [5-chloro-3-ethyl-1H-indole-2-carboxylic acid [2-(4-piperidin-1-yl-phenyl)ethyl]amide] displayed biased allosteric effects by blocking cAMP inhibition mediated by all cannabinoid ligands tested, at the same time having little or no effect on ERK1/2 phosphorylation mediated by a subset of these ligands. Org27569 also displayed negative binding cooperativity with [(3)H]SR141716A [5-(4-chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide]; however, it had minimal effects on binding of cannabinoid agonists. Furthermore, we highlight the need to validate the reported allosteric effects of the endogenous ligands lipoxin A4 and pregnenolone at CB1Rs. Pregnenolone but not lipoxin A4 displaced [(3)H]SR141716A, but there was no functional interaction between either of these ligands and cannabinoid agonists. This study demonstrates an approach to validating and quantifying ligand-biased signaling and allosteric modulation at CB1Rs, revealing ligand-biased "fingerprints" that may ultimately allow the development of improved CB1R-targeted therapies.
Collapse
Affiliation(s)
- Elham Khajehali
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Melbourne, Australia (E.K., D.T.M., P.M.S., A.C., K.L.); and Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (M.G.)
| | - Daniel T Malone
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Melbourne, Australia (E.K., D.T.M., P.M.S., A.C., K.L.); and Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (M.G.)
| | - Michelle Glass
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Melbourne, Australia (E.K., D.T.M., P.M.S., A.C., K.L.); and Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (M.G.)
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Melbourne, Australia (E.K., D.T.M., P.M.S., A.C., K.L.); and Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (M.G.)
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Melbourne, Australia (E.K., D.T.M., P.M.S., A.C., K.L.); and Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (M.G.)
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Melbourne, Australia (E.K., D.T.M., P.M.S., A.C., K.L.); and Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (M.G.)
| |
Collapse
|
5
|
Hjorth S, Karlsson C, Jucaite A, Varnäs K, Wählby Hamrén U, Johnström P, Gulyás B, Donohue SR, Pike VW, Halldin C, Farde L. A PET study comparing receptor occupancy by five selective cannabinoid 1 receptor antagonists in non-human primates. Neuropharmacology 2015; 101:519-30. [PMID: 25791528 DOI: 10.1016/j.neuropharm.2015.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/05/2015] [Accepted: 03/07/2015] [Indexed: 01/14/2023]
Abstract
There is a medical need for safe and efficacious anti-obesity drugs with acceptable side effect profiles. To mitigate the challenge posed by translating target interaction across species and balancing beneficial vs. adverse effects, a positron emission tomography (PET) approach could help guide clinical dose optimization. Thus, as part of a compound differentiation effort, three novel selective CB1 receptor (CB1R) antagonists, developed by AstraZeneca (AZ) for the treatment of obesity, were compared with two clinically tested reference compounds, rimonabant and taranabant, with regard to receptor occupancy relative to dose and exposure. A total of 42 PET measurements were performed in 6 non-human primates using the novel CB1R antagonist radioligand [(11)C]SD5024. The AZ CB1R antagonists bound in a saturable manner to brain CB1R with in vivo affinities similar to that of rimonabant and taranabant, compounds with proven weight loss efficacy in clinical trials. Interestingly, it was found that exposures corresponding to those needed for optimal clinical efficacy of rimonabant and taranabant resulted in a CB1R occupancy typically around ∼20-30%, thus much lower than what would be expected for classical G-protein coupled receptor (GPCR) antagonists in other therapeutic contexts. These findings are also discussed in relation to emerging literature on the potential usefulness of 'neutral' vs. 'classical' CB1R (inverse agonist) antagonists. The study additionally highlighted the usefulness of the radioligand [(11)C]SD5024 as a specific tracer for CB1R in the primate brain, though an arterial input function would ideally be required in future studies to further assure accurate quantitative analysis of specific binding.
Collapse
Affiliation(s)
- Stephan Hjorth
- Biosciences, CVMD Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden
| | - Cecilia Karlsson
- CVMD Translational Medicine Unit, Early Clinical Development, Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden.
| | - Aurelija Jucaite
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Katarina Varnäs
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ulrika Wählby Hamrén
- Quantitative Clinical Pharmacology, Early Clinical Development, Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden
| | - Peter Johnström
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Balázs Gulyás
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sean R Donohue
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Christer Halldin
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Lars Farde
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
6
|
Vauquelin G, Charlton SJ. Exploring avidity: understanding the potential gains in functional affinity and target residence time of bivalent and heterobivalent ligands. Br J Pharmacol 2013; 168:1771-85. [PMID: 23330947 PMCID: PMC3623049 DOI: 10.1111/bph.12106] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 11/05/2012] [Accepted: 11/28/2012] [Indexed: 12/13/2022] Open
Abstract
Bivalent ligands are increasingly important therapeutic agents. Although the naturally occurring antibodies are predominant, it is becoming more common to combine different antibody fragments or even low molecular weight compounds to generate heterobivalent ligands. Such ligands exhibit markedly increased affinity (i.e. avidity) and target residence time when both pharmacophores can bind simultaneously to their target sites. This is because binding of one pharmacophore forces the second tethered one to stay close to its corresponding site. This 'forced proximity' favours its binding and rebinding (once dissociated) to that site. However, rebinding will also take place when the diffusion of freshly dissociated ligands is merely slowed down. The present differential equation-based simulations explore the way both situations affect ligand binding. Both delay the attainment of binding equilibrium (resulting in steep saturation curves) and also increase the target residence time. Competitive ligands are able to interfere in a concentration-dependent manner, although much higher concentrations are required in the 'forced proximity' situation. Also, it is only in that situation that the ligand shows increased affinity. These simulations shed light on two practical consequences. Depending on the pharmacokinetic half-life of the bivalent ligand in the body, it may not have sufficient time to achieve equilibrium with the target. This will result in lower potency than expected, although it would have significant advantages in terms of residence time. In in vitro experiments, the manifestation of steep saturation curves and of accelerated dissociation in the presence of competitive ligands could mistakenly be interpreted as evidence for non-competitive, allosteric interactions.
Collapse
Affiliation(s)
- Georges Vauquelin
- Department Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Brussels, Belgium.
| | | |
Collapse
|
7
|
Zogopoulos P, Vasileiou I, Patsouris E, Theocharis SE. The role of endocannabinoids in pain modulation. Fundam Clin Pharmacol 2013; 27:64-80. [PMID: 23278562 DOI: 10.1111/fcp.12008] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 09/03/2012] [Accepted: 09/21/2012] [Indexed: 12/16/2022]
Abstract
The endocannabinoid system (ES) is comprised of cannabinoid (CB) receptors, their endogenous ligands (endocannabinoids), and proteins responsible for their metabolism. Endocannabinoids serve as retrograde signaling messengers in GABAergic and glutamatergic synapses, as well as modulators of postsynaptic transmission, that interact with other neurotransmitters. Physiological stimuli and pathological conditions lead to differential increases in brain endocannabinoids that regulate distinct biological functions. Furthermore, endocannabinoids modulate neuronal, glial, and endothelial cell function and exert neuromodulatory, anti-excitotoxic, anti-inflammatory, and vasodilatory effects. Analgesia is one of the principal therapeutic targets of cannabinoids. Cannabinoid analgesia is based on the suppression of spinal and thalamic nociceptive neurons, but peripheral sites of action have also been identified. The chronic pain that occasionally follows peripheral nerve injury differs fundamentally from inflammatory pain and is an area of considerable unmet therapeutic need. Over the last years, considerable progress has been made in understanding the role of the ES in the modulation of pain. Endocannabinoids have been shown to behave as analgesics in models of both acute nociception and clinical pain such as inflammation and painful neuropathy. The framework for such analgesic effects exists in the CB receptors, which are found in areas of the nervous system important for pain processing and in immune cells that regulate the neuro-immune interactions that mediate the inflammatory hyperalgesia. The purpose of this review is to present the available research and clinical data, up to date, regarding the ES and its role in pain modulation, as well as its possible therapeutic perspectives.
Collapse
Affiliation(s)
- Panagiotis Zogopoulos
- First Department of Pathology, Medical School, University of Athens, Goudi, Athens, Greece
| | | | | | | |
Collapse
|
8
|
Vauquelin G, Van Liefde I. Radioligand dissociation measurements: potential interference of rebinding and allosteric mechanisms and physiological relevance of the biological model systems. Expert Opin Drug Discov 2012; 7:583-95. [DOI: 10.1517/17460441.2012.687720] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
9
|
Vauquelin G. Determination of drug–receptor residence times by radioligand binding and functional assays: experimental strategies and physiological relevance. MEDCHEMCOMM 2012. [DOI: 10.1039/c2md20015e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
10
|
Direct injection of lipophilic compounds in the organic phase from liquid–liquid extracted plasma samples onto a reversed-phase column. Bioanalysis 2011; 3:1963-73. [DOI: 10.4155/bio.11.177] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: A high-throughput bioanalytical methodology for analysis and quantification of lipophilic pharmaceutical compounds in plasma using liquid–liquid extraction (LLE) was developed. Results: A fast and robust alternative to the widely used protein precipitation of plasma samples is sometimes required in order to avoid matrix effects in MS detection. LLE is known to produce clean extracts and hence reduce levels of matrix components that cause ion suppression. The proposed sample preparation was automated LLE using 96-well plates and a Tecan GenMate 96-tips liquid handling robot. With direct injection of the organic phase (methyl tert-butyl ether: iso-hexane 50:50 v/v) onto a reversed-phase column and without evaporation of the organic phase and reconstitution of the sample, the LLE was no more time consuming than standard protein precipitation, furthermore, matrix effects were minimized. The small injection volume (5 µl) when used with lipophilic compounds and a rapid gradient elution made it possible to inject the organic phase with maintained chromatographic performance. Good chromatographic behavior was confirmed for eight commercially available lipophilic compounds. Conclusions: The proposed method of LLE with injection of the organic phase onto a reversed-phase column in LC–MS/MS is no more time consuming than standard protein precipitation, and matrix effects were minimized, thus making it suitable as a high-throughput bioanalytical methodology for use in drug discovery.
Collapse
|
11
|
Demaegdt H, Gard P, De Backer JP, Lukaszuk A, Szemenyei E, Tóth G, Tourwé D, Vauquelin G. Binding of "AT4 receptor" ligands to insulin regulated aminopeptidase (IRAP) in intact Chinese hamster ovary cells. Mol Cell Endocrinol 2011; 339:34-44. [PMID: 21457753 DOI: 10.1016/j.mce.2011.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/17/2011] [Accepted: 03/22/2011] [Indexed: 01/03/2023]
Abstract
Insulin regulated aminopeptidase (IRAP) recognises "AT(4)-receptor" ligands like angiotensin IV (Ang IV) and peptidomimetics like AL-11. The metabolic stability and high affinity of [(3)H]AL-11 for catalytically active IRAP allowed its detection in Chinese hamster ovary (CHO-K1) cell membranes in the absence of chelators (Demaegdt et al., 2009). Here, we show that, contrary to [(3)H]Ang IV, [(3)H]AL-11 displays high affinity and specificity for IRAP in intact CHO-K1 cells as well. After binding to IRAP at the surface, [(3)H]AL-11 is effectively internalized by an endocytotic process. Unexpectedly, surface binding and internalization of [(3)H]AL-11 was not affected by pretreating the cells with Ang IV but declined with AL-11. In the latter case surface expression of IRAP even increased. After elimination of simpler explanations, it is proposed that metabolically stable "AT(4)-receptor" ligands undergo semi-continuous cycling between the cell surface and endosomal compartments. The in vivo efficacy of stable and unstable "AT(4)-receptor" ligands could therefore differ.
Collapse
Affiliation(s)
- Heidi Demaegdt
- Department of Molecular and Biochemical Pharmacology, Research Group of Experimental Pharmacology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Swinney DC. Molecular Mechanism of Action (MMoA) in Drug Discovery. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2011. [DOI: 10.1016/b978-0-12-386009-5.00009-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|