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Abstract
In this review, the state of the art for compounds affecting the endocannabinoid (eCB) system is described with a focus on the treatment of pain. Amongst directly acting CB receptor ligands, clinical experience with ∆9 -tetrahydracannabinol and medical cannabis in chronic non-cancer pain indicates that there are differences between the benefits perceived by patients and the at best modest effect seen in meta-analyses of randomized controlled trials. The reason for this difference is not known but may involve differences in the type of patients that are recruited, the study conditions that are chosen and the degree to which biases such as reporting bias are operative. Other directly acting CB receptor ligands such as biased agonists and allosteric receptor modulators have not yet reached the clinic. Amongst indirectly acting compounds targeting the enzymes responsible for the synthesis and catabolism of the eCBs anandamide and 2-arachidonoylglycerol, fatty acid amide hydrolase (FAAH) inhibitors have been investigated clinically but were per se not useful for the treatment of pain, although they may be useful for the treatment of post-traumatic stress disorder and cannabis use disorder. Dual-acting compounds targeting this enzyme and other targets such as cyclooxygenase-2 or transient potential vanilloid receptor 1 may be a way forward for the treatment of pain.
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Affiliation(s)
- C J Fowler
- From the, Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
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2
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Keegan BM, Dreitzler AL, Sexton T, Beveridge TJR, Smith HR, Miller MD, Blough BE, Porrino LJ, Childers SR, Howlett AC. Chronic phenmetrazine treatment promotes D 2 dopaminergic and α2-adrenergic receptor desensitization and alters phosphorylation of signaling proteins and local cerebral glucose metabolism in the rat brain. Brain Res 2021; 1761:147387. [PMID: 33631209 PMCID: PMC8552242 DOI: 10.1016/j.brainres.2021.147387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 11/21/2022]
Abstract
Phenmetrazine (PHEN) is a putative treatment for cocaine and psychostimulant recidivism; however, neurochemical changes underlying its activity have not been fully elucidated. We sought to characterize brain homeostatic adaptations to chronic PHEN, specifically on functional brain activity (local cerebral glucose utilization), G-Protein Coupled Receptor-stimulated G-protein activation, and phosphorylation of ERK1/2Thr202/Tyr204, GSK3βTyr216, and DARPP-32Thr34. Male Sprague-Dawley rats were implanted with sub-cutaneous minipumps delivering either saline (vehicle), acute (2-day) or chronic (14-day) low dose (25 mg/kg/day) or high dose (50 mg/kg/day) PHEN. Acute administration of high dose PHEN increased local cerebral glucose utilization measured by 2-[14C]-deoxyglucose uptake in basal ganglia and motor-related regions of the rat brain. However, chronically treated animals developed tolerance to these effects. To identify the neurochemical changes associated with PHEN's activity, we performed [35S]GTPγS binding assays on unfixed and immunohistochemistry on fixed coronal brain sections. Chronic PHEN treatment dose-dependently attenuated D2 dopamine and α2-adrenergic, but not 5-HT1A, receptor-mediated G-protein activation. Two distinct patterns of effects on pERK1/2 and pDARPP-32 were observed: 1) chronic low dose PHEN decreased pERK1/2, and also significantly increased pDARPP-32 levels in some regions; 2) acute and chronic PHEN increased pERK1/2, but chronic high dose PHEN treatment tended to decrease pDARPP-32. Chronic low dose, but not high dose, PHEN significantly reduced pGSK3β levels in several regions. Our study provides definitive evidence that extended length PHEN dosage schedules elicit distinct modes of neuronal acclimatization in cellular signaling. These pharmacodynamic modifications should be considered in drug development for chronic use.
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Affiliation(s)
- Bradley M Keegan
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Annie L Dreitzler
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Tammy Sexton
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Thomas J R Beveridge
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Hilary R Smith
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Mack D Miller
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Bruce E Blough
- Center for Drug Discovery, RTI International, Research Triangle Park, NC 27709, USA
| | - Linda J Porrino
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Steven R Childers
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Allyn C Howlett
- Center for the Neurobiology of Addiction Treatment, Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA.
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3
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Shum C, Dutan L, Annuario E, Warre-Cornish K, Taylor SE, Taylor RD, Andreae LC, Buckley NJ, Price J, Bhattacharyya S, Srivastava DP. Δ 9-tetrahydrocannabinol and 2-AG decreases neurite outgrowth and differentially affects ERK1/2 and Akt signaling in hiPSC-derived cortical neurons. Mol Cell Neurosci 2020; 103:103463. [PMID: 31917333 DOI: 10.1016/j.mcn.2019.103463] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 12/20/2019] [Accepted: 12/30/2019] [Indexed: 12/26/2022] Open
Abstract
Endocannabinoids regulate different aspects of neurodevelopment. In utero exposure to the exogenous psychoactive cannabinoid Δ9-tetrahydrocannabinol (Δ9-THC), has been linked with abnormal cortical development in animal models. However, much less is known about the actions of endocannabinoids in human neurons. Here we investigated the effect of the endocannabinoid 2-arachidonoyl glycerol (2AG) and Δ9-THC on the development of neuronal morphology and activation of signaling kinases, in cortical neurons derived from human induced pluripotent stem cells (hiPSCs). Our data indicate that the cannabinoid type 1 receptor (CB1R), but not the cannabinoid 2 receptor (CB2R), GPR55 or TRPV1 receptors, is expressed in young, immature hiPSC-derived cortical neurons. Consistent with previous reports, 2AG and Δ9-THC negatively regulated neurite outgrowth. Interestingly, acute exposure to both 2AG and Δ9-THC inhibited phosphorylation of serine/threonine kinase extracellular signal-regulated protein kinases (ERK1/2), whereas Δ9-THC also reduced phosphorylation of Akt (aka PKB). Moreover, the CB1R inverse agonist SR 141716A attenuated the decrease in neurite outgrowth and ERK1/2 phosphorylation induced by 2AG and Δ9-THC. Taken together, our data suggest that hiPSC-derived cortical neurons express CB1Rs and are responsive to exogenous cannabinoids. Thus, hiPSC-neurons may represent a good cellular model for investigating the role of the endocannabinoid system in regulating cellular processes in developing human neurons.
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Affiliation(s)
- Carole Shum
- Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry Psychology and Neuroscience, King's College London, London SE5 8AF, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| | - Lucia Dutan
- Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry Psychology and Neuroscience, King's College London, London SE5 8AF, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| | - Emily Annuario
- Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry Psychology and Neuroscience, King's College London, London SE5 8AF, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| | - Katherine Warre-Cornish
- Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry Psychology and Neuroscience, King's College London, London SE5 8AF, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| | - Samuel E Taylor
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK; Centre for Developmental Neurobiology, King's College London, London, UK
| | - Ruth D Taylor
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK; Centre for Developmental Neurobiology, King's College London, London, UK
| | - Laura C Andreae
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK; Centre for Developmental Neurobiology, King's College London, London, UK
| | | | - Jack Price
- Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry Psychology and Neuroscience, King's College London, London SE5 8AF, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK; National Institute for Biological Standards and Control, South Mimms, UK
| | | | - Deepak P Srivastava
- Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry Psychology and Neuroscience, King's College London, London SE5 8AF, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK.
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4
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Grim TW, Morales AJ, Gonek MM, Wiley JL, Thomas BF, Endres GW, Sim-Selley LJ, Selley DE, Negus SS, Lichtman AH. Stratification of Cannabinoid 1 Receptor (CB1R) Agonist Efficacy: Manipulation of CB1R Density through Use of Transgenic Mice Reveals Congruence between In Vivo and In Vitro Assays. J Pharmacol Exp Ther 2016; 359:329-339. [PMID: 27535976 DOI: 10.1124/jpet.116.233163] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 07/21/2016] [Indexed: 01/16/2023] Open
Abstract
Synthetic cannabinoids (SCs) are an emerging class of abused drugs that differ from each other and the phytocannabinoid ∆9-tetrahydrocannabinol (THC) in their safety and cannabinoid-1 receptor (CB1R) pharmacology. As efficacy represents a critical parameter to understanding drug action, the present study investigated this metric by assessing in vivo and in vitro actions of THC, two well-characterized SCs (WIN55,212-2 and CP55,940), and three abused SCs (JWH-073, CP47,497, and A-834,735-D) in CB1 (+/+), (+/-), and (-/-) mice. All drugs produced maximal cannabimimetic in vivo effects (catalepsy, hypothermia, antinociception) in CB1 (+/+) mice, but these actions were essentially eliminated in CB1 (-/-) mice, indicating a CB1R mechanism of action. CB1R efficacy was inferred by comparing potencies between CB1 (+/+) and (+/-) mice [+/+ ED50 /+/- ED50], the latter of which has a 50% reduction of CB1Rs (i.e., decreased receptor reserve). Notably, CB1 (+/-) mice displayed profound rightward and downward shifts in the antinociception and hypothermia dose-response curves of low-efficacy compared with high-efficacy cannabinoids. In vitro efficacy, quantified using agonist-stimulated [35S]GTPγS binding in spinal cord tissue, significantly correlated with the relative efficacies of antinociception (r = 0.87) and hypothermia (r = 0.94) in CB1 (+/-) mice relative to CB1 (+/+) mice. Conversely, drug potencies for cataleptic effects did not differ between these genotypes and did not correlate with the in vitro efficacy measure. These results suggest that evaluation of antinociception and hypothermia in CB1 transgenic mice offers a useful in vivo approach to determine CB1R selectivity and efficacy of emerging SCs, which shows strong congruence with in vitro efficacy.
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Affiliation(s)
- T W Grim
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - A J Morales
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - M M Gonek
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - J L Wiley
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - B F Thomas
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - G W Endres
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - L J Sim-Selley
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - D E Selley
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - S S Negus
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
| | - A H Lichtman
- Virginia Commonwealth University-Pharmacology and Toxicology, Richmond, Virginia (T.W.G., A.J.M., M.M.G., L.J.S.-S., D.E.S., S.S.N., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W., B.F.T.); Cayman Chemical, Ann Arbor, Michigan (G.W.E.)
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5
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Grim TW, Samano KL, Ignatowska-Jankowska B, Tao Q, Sim-Selly LJ, Selley DE, Wise LE, Poklis A, Lichtman AH. Pharmacological characterization of repeated administration of the first generation abused synthetic cannabinoid CP47,497. J Basic Clin Physiol Pharmacol 2016; 27:217-28. [PMID: 27149200 PMCID: PMC5644386 DOI: 10.1515/jbcpp-2015-0118] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/30/2015] [Indexed: 04/08/2023]
Abstract
A series of in vivo and in vitro assays were conducted to characterize the pharmacological effects of the first generation abused synthetic cannabinoid CP47,497, a racemic bicyclic cannabinoid that is similar in structure to the potent, high-efficacy synthetic cannabinoid CP55,940. CP47,497 was less efficacious than CP55,940 in activating G-proteins and dose-dependently produced common CB1 receptor-dependent pharmacological effects (i.e. catalepsy, hypothermia, antinociception, and hypolocomotion). CP47,497 also substituted for Δ9-tetrahydrocannabinol (THC) in the mouse drug discrimination, indicating that both drugs elicited a similar interceptive stimulus. The pharmacological effects of CP47,497 underwent tolerance following repeated administration and showed cross-tolerance following repeated THC administration, further suggesting a common cannabimimetic mechanism of action. Finally, the CB1 receptor antagonist rimonabant precipitated similar magnitudes of somatic withdrawal responses in mice treated repeatedly with THC or CP47,497. Taken together, these data verify the acute cannabimimetic effects of CP47,497, and indicate tolerance and dependence following repeated administration. The assays used here provide a straightforward approach to characterize the emerging next generation of abused synthetic cannabinoids.
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Affiliation(s)
| | | | | | - Qing Tao
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Laura J. Sim-Selly
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Dana E. Selley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Laura E. Wise
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Alphonse Poklis
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA; Department of Pathology, Virginia Commonwealth University, Richmond, VA, USA; and Department of Forensic Science, Virginia Commonwealth University, Richmond, VA, USA
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6
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Howlett AC, Reggio PH, Childers SR, Hampson RE, Ulloa NM, Deutsch DG. Endocannabinoid tone versus constitutive activity of cannabinoid receptors. Br J Pharmacol 2012; 163:1329-43. [PMID: 21545414 DOI: 10.1111/j.1476-5381.2011.01364.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This review evaluates the cellular mechanisms of constitutive activity of the cannabinoid (CB) receptors, its reversal by inverse agonists, and discusses the pitfalls and problems in the interpretation of the research data. The notion is presented that endogenously produced anandamide (AEA) and 2-arachidonoylglycerol (2-AG) serve as autocrine or paracrine stimulators of the CB receptors, giving the appearance of constitutive activity. It is proposed that one cannot interpret inverse agonist studies without inference to the receptors' environment vis-à-vis the endocannabinoid agonists which themselves are highly lipophilic compounds with a preference for membranes. The endocannabinoid tone is governed by a combination of synthetic pathways and inactivation involving transport and degradation. The synthesis and degradation of 2-AG is well characterized, and 2-AG has been strongly implicated in retrograde signalling in neurons. Data implicating endocannabinoids in paracrine regulation have been described. Endocannabinoid ligands can traverse the cell's interior and potentially be stored on fatty acid-binding proteins (FABPs). Molecular modelling predicts that the endocannabinoids derived from membrane phospholipids can laterally diffuse to enter the CB receptor from the lipid bilayer. Considering that endocannabinoid signalling to CB receptors is a much more likely scenario than is receptor activation in the absence of agonist ligands, researchers are advised to refrain from assuming constitutive activity except for experimental models known to be devoid of endocannabinoid ligands.
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Affiliation(s)
- Allyn C Howlett
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA.
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7
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Wiley JL, Selley DE, Wang P, Kottani R, Gadthula S, Mahadeven A. 3-Substituted pyrazole analogs of the cannabinoid type 1 (CB₁) receptor antagonist rimonabant: cannabinoid agonist-like effects in mice via non-CB₁, non-CB₂ mechanism. J Pharmacol Exp Ther 2011; 340:433-44. [PMID: 22085649 DOI: 10.1124/jpet.111.187815] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The prototypic cannabinoid type 1 (CB₁) receptor antagonist/inverse agonist, rimonabant, is comprised of a pyrazole core surrounded by a carboxyamide with terminal piperidine group (3-substituent), a 2,4-dichlorophenyl group (1-substituent), a 4-chlorophenyl group (5-substituent), and a methyl group (4-substituent). Previous structure-activity relationship (SAR) analysis has suggested that the 3-position may be involved in receptor recognition and agonist activity. The goal of the present study was to develop CB₁-selective compounds and explore further the SAR of 3-substitution on the rimonabant template. 3-Substituted analogs with benzyl and alkyl amino, dihydrooxazole, and oxazole moieties were synthesized and evaluated in vitro and in vivo. Several notable patterns emerged. First, most of the analogs exhibited CB₁ selectivity, with many lacking affinity for the CB₂ receptor. Affinity tended to be better when [³H]5-(4-chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide (SR141716), rather than [³H](-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxy-propyl)cyclohexanol (CP55,940), was used as the binding radioligand. Second, many of the analogs produced an agonist-like profile of effects in mice (i.e., suppression of activity, antinociception, hypothermia, and immobility); however, their potencies were not well correlated with their CB₁ binding affinities. Further assessment of selected analogs showed that none were effective antagonists of the effects of Δ⁹-tetrahydrocannabinol in mice, their agonist-like effects were not blocked by rimonabant, they were active in vivo in CB₁⁻/⁻ mice, and they failed to stimulate guanosine-5'-O-(3-[³⁵S]thio)-triphosphate binding. Several analogs were inverse agonists in the latter assay. Together, these results suggest that this series of 3-substituted pyrazole analogs represent a novel class of CB₁-selective cannabinoids that produce agonist-like effects in mice through a non-CB₁, non-CB₂ mechanism.
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Affiliation(s)
- Jenny L Wiley
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA.
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8
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The G protein-coupled cannabinoid-1 (CB1) receptor of mammalian brain: inhibition by phthalate esters in vitro. Neurochem Int 2011; 59:706-13. [PMID: 21763743 DOI: 10.1016/j.neuint.2011.06.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/21/2011] [Accepted: 06/23/2011] [Indexed: 01/29/2023]
Abstract
This research examines the in vitro interaction of phthalate diesters and monoesters with the G protein-coupled cannabinoid 1 (CB(1)) receptor, a presynaptic complex involved in the regulation of synaptic activity in mammalian brain. The diesters, n-butylbenzylphthalate (nBBP), di-n-hexylphthalate (DnHP), di-n-butylphthalate (DnBP), di-2-ethylhexylphthalate (DEHP), di-isooctylphthalate (DiOP) and di-n-octylphthalate (DnOP) inhibited the specific binding of the CB(1) receptor agonist [(3)H]CP-55940 to mouse whole brain membranes at micromolar concentrations (IC(50)s: nBBP 27.4 μM; DnHP 33.9 μM; DnBP 45.9 μM; DEHP 47.4 μM; DiOP 55.4 μM; DnOP 75.2 μM). DnHP, DnBP and nBBP achieved full (or close to full) blockade of [(3)H]CP-55940 binding, whereas DEHP, DiOP and DnOP produced partial (55-70%) inhibition. Binding experiments with phenylmethane-sulfonylfluoride (PMSF) indicated that the ester linkages of nBBP and DnBP remain intact during assay. The monoesters mono-2-ethylhexylphthalate (M2EHP) and mono-isohexylphthalate (MiHP) failed to reach IC(50) at 150 μM and mono-n-butylphthalate (MnBP) was inactive. Inhibitory potencies in the [(3)H]CP-55940 binding assay were positively correlated with inhibition of CB(1) receptor agonist-stimulated binding of [(35)S]GTPγS to the G protein, demonstrating that phthalates cause functional impairment of this complex. DnBP, nBBP and DEHP also inhibited binding of [(3)H]SR141716A, whereas inhibition with MiHP was comparatively weak and MnBP had no effect. Equilibrium binding experiments with [(3)H]SR141716A showed that phthalates reduce the B(max) of radioligand without changing its K(d). DnBP and nBBP also rapidly enhanced the dissociation of [(3)H]SR141716A. Our data are consistent with an allosteric mechanism for inhibition, with phthalates acting as relatively low affinity antagonists of CB(1) receptors and cannabinoid agonist-dependent activation of the G-protein. Further studies are warranted, since some phthalate esters may have potential to modify CB(1) receptor-dependent behavioral and physiological outcomes in the whole animal.
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9
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The actions of benzophenanthridine alkaloids, piperonyl butoxide and (S)-methoprene at the G-protein coupled cannabinoid CB1 receptor in vitro. Eur J Pharmacol 2011; 654:26-32. [DOI: 10.1016/j.ejphar.2010.11.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Revised: 09/30/2010] [Accepted: 11/26/2010] [Indexed: 01/25/2023]
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10
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Structural and pharmacological analysis of O-2050, a putative neutral cannabinoid CB(1) receptor antagonist. Eur J Pharmacol 2010; 651:96-105. [PMID: 21114999 DOI: 10.1016/j.ejphar.2010.10.085] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 10/14/2010] [Accepted: 10/29/2010] [Indexed: 12/26/2022]
Abstract
Rimonabant, the prototypic antagonist of cannabinoid CB(1) receptors, has been reported to have inverse agonist properties at higher concentrations, which may complicate its use as a tool for mechanistic evaluation of cannabinoid pharmacology. Consequently, recent synthesis efforts have concentrated on discovery of a neutral antagonist using a variety of structural templates. The purpose of this study was to evaluate the pharmacological properties of the putative neutral cannabinoid CB(1) receptor antagonist O-2050, a sulfonamide side chain analog of Δ(8)-tetrahydrocannabinol. O-2050 and related sulfonamide cannabinoids exhibited good affinity for both cannabinoid CB(1) and CB(2) receptors. While the other sulfonamide analogs produced cannabinoid agonist effects in vivo (e.g., activity suppression, antinociception, and hypothermia), O-2050 stimulated activity and was inactive in the other two tests. O-2050 also decreased food intake in mice, an effect that was reminiscent of that produced by rimonabant. Unlike rimonabant, however, O-2050 did not block the effects of cannabinoid agonists in vivo, even when administered i.c.v. In contrast, O-2050 antagonized the in vitro effects of cannabinoid agonists in [(35)S]GTPγS and mouse vas deferens assays without having activity on its own in either assay. Further evaluation revealed that O-2050 fully and dose-dependently substituted for Δ(9)-tetrahydrocannabinol in a mouse drug discrimination procedure (a cannabinoid agonist effect) and that it inhibited forskolin-stimulated cyclic AMP signaling with a maximum efficacy of approximately half that of the full agonist CP55,940 [(-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxy-propyl)cyclohexanol]. Together, these results suggest that O-2050 is not a viable candidate for classification as a neutral cannabinoid CB(1) receptor antagonist.
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11
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Huffman JW, Hepburn SA, Lyutenko N, Thompson ALS, Wiley JL, Selley DE, Martin BR. 1-Bromo-3-(1',1'-dimethylalkyl)-1-deoxy-Δ(8)-tetrahydrocannabinols: New selective ligands for the cannabinoid CB(2) receptor. Bioorg Med Chem 2010; 18:7809-15. [PMID: 20943404 PMCID: PMC2978510 DOI: 10.1016/j.bmc.2010.09.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 09/16/2010] [Accepted: 09/22/2010] [Indexed: 10/19/2022]
Abstract
Δ(8)-Tetrahydrocannabinol (26), 3-(1',1'-dimethylbutyl)- (12), 3-(1',1'-dimethylpentyl)- (13), 3-(1',1'-dimethylhexyl)- (14) and 3-(1',1'-dimethylheptyl)-Δ(8)-tetrahydrocannabinol (15) have been converted into the corresponding 1-bromo-1-deoxy-Δ(8)-tetrahydrocannabinols (25, 8-11). This was accomplished using a protocol developed in our laboratory in which the trifluoromethanesulfonate of a phenol undergoes palladium mediated coupling with pinacolborane. Reaction of this dioxaborolane with aqueous-methanolic copper(II) bromide provides the aryl bromide. The affinities of these bromo cannabinoids for the cannabinoid CB(1) and CB(2) receptors were determined. All of these compounds showed selectivity for the CB(2) receptor and one of them, 1-bromo-1-deoxy-3-(1',1'-dimethylhexyl)-Δ(8)-tetrahydrocannabinol (10), exhibits 52-fold selectivity for this receptor with good (28nM) affinity.
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Affiliation(s)
- John W Huffman
- Howard L. Hunter Laboratory, Clemson University, Clemson, SC 29634-0973, United States.
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12
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Walentiny DM, Vann RE, Warner JA, King LS, Seltzman HH, Navarro HA, Twine CE, Thomas BF, Gilliam AF, Gilmour BP, Carroll FI, Wiley JL. Kappa opioid mediation of cannabinoid effects of the potent hallucinogen, salvinorin A, in rodents. Psychopharmacology (Berl) 2010; 210:275-84. [PMID: 20354680 PMCID: PMC3013230 DOI: 10.1007/s00213-010-1827-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 03/06/2010] [Indexed: 12/21/2022]
Abstract
RATIONALE Salvinorin A, the primary psychoactive derivative of the hallucinogenic herb Salvia divinorum, is a potent and highly selective kappa-opioid receptor (KOR) agonist. Several recent studies, however, have suggested endocannabinoid system mediation of some of its effects. OBJECTIVES This study represents a systematic examination of this hypothesis. METHODS Salvinorin A was isolated from S. divinorum and was evaluated in a battery of in vitro and in vivo procedures designed to detect cannabinoid activity, including CB(1) receptor radioligand and [(35)S]GTPgammaS binding, calcium flux assay, in vivo cannabinoid screening tests, and drug discrimination. RESULTS Salvinorin A did not bind to nor activate CB(1) receptors. In vivo salvinorin A produced pronounced hypolocomotion and antinociception (and to a lesser extent, hypothermia). These effects were blocked by the selective KOR antagonist, JDTic, but not by the CB(1) receptor antagonist rimonabant. Interestingly, however, rimonabant attenuated KOR activation stimulated by U69,593 in a [(35)S]GTPgammaS assay. Salvinorin A did not substitute for Delta(9)-tetrahydrocannabinol (THC) in mice trained to discriminate THC. CONCLUSIONS These findings suggest that similarities in the pharmacological effects of salvinorin A and those of cannabinoids are mediated by its activation of KOR rather than by any direct action of salvinorin A on the endocannabinoid system. Further, the results suggest that rimonabant reversal of salvinorin A effects in previous studies may be explained in part by rimonabant attenuation of KOR activation.
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Affiliation(s)
- D. Matthew Walentiny
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, P.O. Box 980613, Richmond, VA 23298-0613, USA
| | - Robert E. Vann
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, P.O. Box 980613, Richmond, VA 23298-0613, USA
| | - Jonathan A. Warner
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, P.O. Box 980613, Richmond, VA 23298-0613, USA
| | - Lindsey S. King
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, P.O. Box 980613, Richmond, VA 23298-0613, USA
| | - Herbert H. Seltzman
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC 27709-2194, USA
| | - Hernán A. Navarro
- Center for Pharmacology and Toxicology, Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Charles E. Twine
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC 27709-2194, USA
| | - Brian F. Thomas
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC 27709-2194, USA
| | - Anne F. Gilliam
- Center for Pharmacology and Toxicology, Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Brian P. Gilmour
- Center for Pharmacology and Toxicology, Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - F. Ivy Carroll
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC 27709-2194, USA
| | - Jenny L. Wiley
- Center for Pharmacology and Toxicology, Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
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13
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Novel sulfamoyl benzamides as selective CB2 agonists with improved in vitro metabolic stability. Bioorg Med Chem Lett 2010; 20:387-91. [DOI: 10.1016/j.bmcl.2009.10.062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/13/2009] [Accepted: 10/14/2009] [Indexed: 01/18/2023]
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14
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Capasso A, Gallo C. Molecules Acting on CB1 Receptor and their Effects on Morphine Withdrawal In Vitro. Open Biochem J 2009; 3:78-84. [PMID: 20111725 PMCID: PMC2811858 DOI: 10.2174/1874091x00903010078] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 11/22/2022] Open
Abstract
Several pharmacological studies indicate that CB1 cannabinoid receptors (CB1Rs) are present in guinea pig ileum (GPI) and their activation reduce the acetylcholine (Ach) release. Dependence can be induced and measured in vitro by using GPI and the contraction due to opioid withdrawal is caused by acetylcholine release. Design of molecules acting on the CB1Rs are widely studied and the large availaibility of CB1Rs agonists and antagonists provides powerful tools to determine the role of these receptors in mediating some of physiological and pharmacological effects in the myenteric neurones. Given the relationship between CB1Rs/Opioid Withdrawal/Ach system, in the present paper we have designed six new CB1Rs agonists named A-F and evaluated their role in mediating morphine withdrawal in GPI. Also, a comparative study was performed by using the CB1Rs synthetic cannabinoid WIN 55,212-2 and CP 55,940. The results of our experiments indicate that both WIN 55,212-2 and CP 55,940 (1x10-8-5x10-8-1x10-7 M) were able to reduce morphine withdrawal in a concentration-dependent manner. Very similar results were obtained with the new CB1Rs agonists (A-F) used at same concentrations. The results of our experiments indicate that CB1Rs are involved in the control of morphine withdrawal in vitro thus confirming an important functional interaction between the cannabinoid and opioid system.
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Affiliation(s)
- Anna Capasso
- Department of Pharmaceutical Sciences, University of Salerno, Via Ponte Don Melillo (84084) Fisciano, Salerno, Italy
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15
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Chu GH, Saeui CT, Worm K, Weaver DG, Goodman AJ, Broadrup RL, Cassel JA, DeHaven RN, LaBuda CJ, Koblish M, Brogdon B, Smith S, Bourdonnec BL, Dolle RE. Novel pyridine derivatives as potent and selective CB2 cannabinoid receptor agonists. Bioorg Med Chem Lett 2009; 19:5931-5. [DOI: 10.1016/j.bmcl.2009.08.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 08/13/2009] [Accepted: 08/13/2009] [Indexed: 11/24/2022]
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16
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Worm K, Weaver DG, Green RC, Saeui CT, Dulay DMS, Barker WM, Cassel JA, Stabley GJ, DeHaven RN, LaBuda CJ, Koblish M, Brogdon BL, Smith SA, Dolle RE. Discovery of N-(3-(morpholinomethyl)-phenyl)-amides as potent and selective CB2 agonists. Bioorg Med Chem Lett 2009; 19:5004-8. [DOI: 10.1016/j.bmcl.2009.07.057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 07/08/2009] [Accepted: 07/09/2009] [Indexed: 01/27/2023]
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17
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Kreitzer FR, Stella N. The therapeutic potential of novel cannabinoid receptors. Pharmacol Ther 2009; 122:83-96. [PMID: 19248809 DOI: 10.1016/j.pharmthera.2009.01.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 01/21/2009] [Indexed: 12/20/2022]
Abstract
Cannabinoids produce a plethora of biological effects, including the modulation of neuronal activity through the activation of CB(1) receptors and of immune responses through the activation of CB(2) receptors. The selective targeting of either of these two receptor subtypes has clear therapeutic value. Recent evidence indicates that some of the cannabinomimetic effects previously thought to be produced through CB(1) and/or CB(2) receptors, be they on neuronal activity, on the vasculature tone or immune responses, still persist despite the pharmacological blockade or genetic ablation of CB(1) and/or CB(2) receptors. This suggests that additional cannabinoid and cannabinoid-like receptors exist. Here we will review this evidence in the context of their therapeutic value and discuss their true belonging to the endocannabinoid signaling system.
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Affiliation(s)
- Faith R Kreitzer
- Department of Pharmacology, University of Washington, Seattle, WA 98115-7280, USA
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18
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Huffman JW, Thompson ALS, Wiley JL, Martin BR. Synthesis and pharmacology of 1-deoxy analogs of CP-47,497 and CP-55,940. Bioorg Med Chem 2008; 16:322-35. [PMID: 17919913 PMCID: PMC2262798 DOI: 10.1016/j.bmc.2007.09.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 09/14/2007] [Accepted: 09/19/2007] [Indexed: 10/22/2022]
Abstract
A series of 1-deoxy analogs of CP-47,497 (8 and 13, n=0-7) and 1-deoxy analogs of CP-55,940 (9, n=0-7) have been synthesized and their affinities for the cannabinoid CB(1) and CB(2) receptors have been determined. Although the majority of these compounds exhibit selectivity for the CB(2) receptor, none have greater than modest affinity for either receptor. The interactions of these 1-deoxy nontraditional cannabinoids with the CB(2) receptor are discussed.
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Affiliation(s)
- John W Huffman
- Howard L. Hunter Laboratory, Clemson University, Clemson, SC 29634-0973, USA.
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19
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Castelli MP, Paola Piras A, D'Agostino A, Pibiri F, Perra S, Gessa GL, Maccarrone M, Pistis M. Dysregulation of the endogenous cannabinoid system in adult rats prenatally treated with the cannabinoid agonist WIN 55,212-2. Eur J Pharmacol 2007; 573:11-9. [PMID: 17644084 DOI: 10.1016/j.ejphar.2007.06.047] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 06/21/2007] [Accepted: 06/26/2007] [Indexed: 12/20/2022]
Abstract
Cannabis is widely abused by women at reproductive age and during pregnancy. Animal studies showed a particular vulnerability of the developing brain to prenatal chronic cannabinoid administration. We determined whether prenatal exposure to WIN 55,212-2, a potent cannabinoid receptor agonist, affected (1) density, affinity and/or function of cannabinoid CB(1) receptors, (2) endogenous levels of the endocannabinoid anandamide, (3) activities of the major anandamide synthesising and hydrolysing enzymes, N-acyl-phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH), respectively, in brain areas of adult male offspring rats. Furthermore, the effect of prenatal WIN 55,212-2 on spontaneous motility was analyzed. Pregnant rats were treated daily with WIN 55,212-2 (0.5 mg/kg, gestation day 5-20) or vehicle. [(3)H]CP 55,940 and WIN 55,212-2-stimulated [(35)S] GTPgammaS binding were carried out in cerebellum, cerebral cortex, hippocampus, striatum and limbic areas of male adult offspring. Levels of anandamide, FAAH and NAPE-PLD activity were also determined. EC(50) values for WIN 55,212-2-stimulated [(35)S]GTPgammaS binding were significantly different in hippocampus (-26%) and striatum (+27%) in WIN 55,212-2-treated rats. Cannabinoid CB(1) receptor density and affinity were not affected in any analyzed region. In the striatum, increased anandamide levels were associated with reduced FAAH and enhanced NAPE-PLD activities. Opposite changes in anandamide levels and enzymatic activities were detected in limbic areas of WIN 55,212-2-treated rats. Ambulatory activity between WIN 55,212-2- and vehicle-treated adult offspring did not vary. Our results show that prenatal exposure to cannabinoid agonist induces a long-term alteration of endocannabinoid system in brain areas involved in learning-memory, motor activity and emotional behavior.
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Affiliation(s)
- M Paola Castelli
- Bernard B. Brodie Department of Neuroscience, University of Cagliari, 09042 Monserrato, Italy.
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20
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Araya KA, David Pessoa Mahana C, González LG. Role of cannabinoid CB1 receptors and Gi/o protein activation in the modulation of synaptosomal Na+,K+-ATPase activity by WIN55,212-2 and delta(9)-THC. Eur J Pharmacol 2007; 572:32-9. [PMID: 17644088 DOI: 10.1016/j.ejphar.2007.06.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 05/29/2007] [Accepted: 06/07/2007] [Indexed: 11/21/2022]
Abstract
In the present study, we evaluated the effects of the synthetic cannabinoid receptor agonist (R)-(+)-[2,3-Dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone mesylate (WIN55,212-2) and the active component of Cannabis delta-9-tetrahydrocannabinol (triangle up(9)-THC) on Na(+),K(+)-ATPase activity in synaptosomal mice brain preparation. Additionally, the potential exogenous cannabinoids and endogenous opioid peptides interaction as well as the role of G(i/o) proteins in mediating Na(+),K(+)-ATPase activation were also explored. The ouabain-sensitive Na(+),K(+)-ATPase activity was measured in whole-brain pure intact synaptosomes (obtained by Percoll gradient method) of female CF-1 mice and was calculated as the difference between the total and the ouabain (1 mM)-insensitive Na(+),K(+)-ATPase activities. Incubation in vitro of the synaptosomes with WIN55,212-2 (0.1 pM-10 microM) or triangle up(9)-THC (0.1 pM-0.1 microM), in a concentration-dependent manner, stimulated ouabain-sensitive Na(+),K(+)-ATPase activity. WIN55,212-2 was less potent but more efficacious than triangle up(9)-THC. N-(Piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM-251) (10 nM), a CB(1) cannabinoid receptor selective antagonist, had not effect per se but antagonized the enhancement of Na(+),K(+)-ATPase activity induced by both, WIN55,212-2 and triangle up(9)-THC. AM-251 produced a significant reduction in the E(max) of cannabinoid-induced increase in Na(+),K(+)-ATPase activity, but did not significantly modify their EC(50). On the other hand, co-incubation with naloxone (1 microM), an opioid receptor antagonist, did not significantly modify the effect of WIN55,212-2 and completely failed to modify the effect of triangle up(9)-THC on synaptosomal Na(+),K(+)-ATPase. Finally, pre-incubation with 0.5 microg of pertussis toxin (G(i/o) protein blocker) completely abolished the enhancement of ouabain-sensitive Na(+),K(+)-ATPase activity induced by WIN55,212-2. A lower dose, 0.25 microg, decreased the E(max) of WIN55,212-2 by 70% but did not significantly affect its EC(50). These results suggest that WIN55212-2 and triangle up(9)-THC indirectly enhance Na(+),K(+)-ATPase activity in the brain by activating cannabinoid CB(1) receptors in a naloxone-insensitive manner. In addition, the effect of WIN55,212-2 on neuronal Na(+),K(+)-ATPase is apparently due to activation of G(i/o) proteins.
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Affiliation(s)
- Katherine A Araya
- Department of Pharmacy (Division of Molecular Pharmacology), Faculty of Chemistry, Pontificia Universidad Católica de Chile, Casilla 306, Santiago, 6094411, Chile
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21
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Biaryl cannabinoid mimetics--synthesis and structure-activity relationship. Bioorg Med Chem Lett 2007; 17:3652-6. [PMID: 17507224 DOI: 10.1016/j.bmcl.2007.04.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 04/10/2007] [Accepted: 04/16/2007] [Indexed: 10/23/2022]
Abstract
Synthesis, in vitro biological evaluation, and structure-activity relationships of a biaryl cannabinoid mimetic 2 are reported. Variations in the substitution pattern yielded a number of agonists with low nanomolar affinity. Replacing the phenol group by a methyl morpholino acetate group led to compound 28, a 500-fold selective CB(2) receptor agonist.
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22
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Manera C, Benetti V, Castelli MP, Cavallini T, Lazzarotti S, Pibiri F, Saccomanni G, Tuccinardi T, Vannacci A, Martinelli A, Ferrarini PL. Design, synthesis, and biological evaluation of new 1,8-naphthyridin-4(1H)-on-3-carboxamide and quinolin-4(1H)-on-3-carboxamide derivatives as CB2 selective agonists. J Med Chem 2006; 49:5947-57. [PMID: 17004710 DOI: 10.1021/jm0603466] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
On the basis of docking studies carried out using the recently published cannabinoid receptor models,35 new 1,8-naphthyridin-4(1H)-on-3-carboxamide and quinolin-4(1H)-on-3-carboxamide derivatives were designed, synthesized, and tested for their affinities toward the cannabinoid CB1 and CB2 receptors. Compound 10, which presented p-fluorobenzyl and carboxycycloheptylamide substituents bound in the 1 and 3 positions of the 1,8-naphthyiridine-4-one nucleus, showed a high CB2 affinity with a Ki of 1.0 nM. The substitution of the naphthyridine-4-one nucleus with the quinoline-4-one system determined a general increase in CB2 affinity. In particular, the N-cyclohexyl-7-chloro-1-(2-morpholin-4-ylethyl)quinolin-4(1H)-on-3-carboxamide (40) possessed a remarkable affinity, with Ki of 3.3 nM, which was also accompanied by a high selectivity for the CB2 receptor (Ki(CB1)/Ki(CB2) ratio greater than 303). Moreover, the [35S]GTPgamma binding assay and functional studies on human basophils indicated that the 1,8-naphthyridin-4(1H)-on-3-carboxamide derivatives behaved as CB1 and CB2 receptor agonists.
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Affiliation(s)
- Clementina Manera
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy.
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23
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Nakamura-Palacios EM, Moerschbaecher JM, Barker LA. The Pharmacology of SR 141716A: A Review. CNS DRUG REVIEWS 2006. [DOI: 10.1111/j.1527-3458.1999.tb00085.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Childers SR. Activation of G-proteins in brain by endogenous and exogenous cannabinoids. AAPS JOURNAL 2006; 8:E112-7. [PMID: 16584117 PMCID: PMC2751429 DOI: 10.1208/aapsj080113] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biological response to cannabinoid agonist begins when the agonist-bound receptor activates G-protein G(alpha) subunits, thus initiating a cascade of signal transduction pathways. For this reason, information about cannabinoid receptors/G-protein coupling is critical to understand both the acute and chronic actions of cannabinoids. This review focuses on these mechanisms, predominantly examining the ability of cannabinoid agonists to activate G-proteins in brain with agonist-stimulated [(35)S]guanylyl-5'-O-(gamma-thio)-triphosphate ([(35)S]GTPgammaS) binding. Acute efficacies of cannabinoid agonists at the level of G-protein activation depend not only on the ability of the agonist to induce a high affinity state in G(alpha) for GTP, but also to induce a low affinity for GDP. When several agonists are compared, it is clear that cannabinoid agonists differ considerably in their efficacy. Both WIN 55212-2 and levonantradol are full agonists, while Delta(9)-tetrahydrocannabinol is a weak partial agonist. Of interest, anandamide and its stable analog methanandamide are partial agonists. Chronic treatment in vivo with cannabinoids produces significant tolerance to the physiological and behavioral effects of these drugs, and several studies have shown that this is accompanied by a significant loss in the ability of cannabinoid receptors to couple to G-proteins in brain. These effects vary across different brain regions and are usually (but not always) accompanied by loss of cannabinoid receptor binding. Although the relationship between cannabinoid receptor desensitization and tolerance has not yet been established, these mechanisms may represent events that lead to a loss of cannabinoid agonist response and development of tolerance.
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Affiliation(s)
- Steven R Childers
- Department of Physiology and Pharmacology, Center for the Neurobiological Investigation of Drug Abuse, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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25
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Egerton A, Allison C, Brett RR, Pratt JA. Cannabinoids and prefrontal cortical function: Insights from preclinical studies. Neurosci Biobehav Rev 2006; 30:680-95. [PMID: 16574226 DOI: 10.1016/j.neubiorev.2005.12.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Revised: 11/18/2005] [Accepted: 12/19/2005] [Indexed: 10/24/2022]
Abstract
Marijuana use has been associated with disordered cognition across several domains influenced by the prefrontal cortex (PFC). Here, we review the contribution of preclinical research to understanding the effects of cannabinoids on cognitive ability, and the mechanisms by which cannabinoids may affect the neurochemical processes in the PFC that are associated with these impairments. In rodents, acute administration of cannabinoid agonists produces deficits in working memory, attentional function and reversal learning. These effects appear to be largely dependent on CB1 cannabinoid receptor activation. Preclinical studies also indicate that the endogenous cannabinoid system may tonically regulate some mnemonic processes. Effects of cannabinoids on cognition may be mediated via interaction with neurochemical processes in the PFC and hippocampus. In the PFC, cannabinoids may alter dopaminergic, cholinergic and serotonergic transmission. These mechanisms may underlie cognitive impairments observed following marijuana intake in humans, and may also be relevant to other disorders of cognition. Preclinical research will further enhance our understanding of the interactions between the cannabinoid system and cognitive functioning.
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Affiliation(s)
- Alice Egerton
- Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, Glasgow G4 0NR, UK
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26
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Abstract
Mammalian tissues express at least two types of cannabinoid receptor, CB1 and CB2, both G protein coupled. CB1 receptors are expressed predominantly at nerve terminals where they mediate inhibition of transmitter release. CB2 receptors are found mainly on immune cells, one of their roles being to modulate cytokine release. Endogenous ligands for these receptors (endocannabinoids) also exist. These are all eicosanoids; prominent examples include arachidonoylethanolamide (anandamide) and 2-arachidonoyl glycerol. These discoveries have led to the development of CB1- and CB2-selective agonists and antagonists and of bioassays for characterizing such ligands. Cannabinoid receptor antagonists include the CB1-selective SR141716A, AM251, AM281 and LY320135, and the CB2-selective SR144528 and AM630. These all behave as inverse agonists, one indication that CB1 and CB2 receptors can exist in a constitutively active state. Neutral cannabinoid receptor antagonists that seem to lack inverse agonist properties have recently also been developed. As well as acting on CB1 and CB2 receptors, there is convincing evidence that anandamide can activate transient receptor potential vanilloid type 1 (TRPV1) receptors. Certain cannabinoids also appear to have non-CB1, non-CB2, non-TRPV1 targets, for example CB2-like receptors that can mediate antinociception and "abnormal-cannabidiol" receptors that mediate vasorelaxation and promote microglial cell migration. There is evidence too for TRPV1-like receptors on glutamatergic neurons, for alpha2-adrenoceptor-like (imidazoline) receptors at sympathetic nerve terminals, for novel G protein-coupled receptors for R-(+)-WIN55212 and anandamide in the brain and spinal cord, for novel receptors for delta9-tetrahydrocannabinol and cannabinol on perivascular sensory nerves and for novel anandamide receptors in the gastro-intestinal tract. The presence of allosteric sites for cannabinoids on various ion channels and non-cannabinoid receptors has also been proposed. In addition, more information is beginning to emerge about the pharmacological actions of the non-psychoactive plant cannabinoid, cannabidiol. These recent advances in cannabinoid pharmacology are all discussed in this review.
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MESH Headings
- Animals
- Biological Assay
- Cannabinoids/pharmacology
- Humans
- Ligands
- Receptor, Cannabinoid, CB1/classification
- Receptor, Cannabinoid, CB1/drug effects
- Receptor, Cannabinoid, CB1/physiology
- Receptor, Cannabinoid, CB2/drug effects
- Receptor, Cannabinoid, CB2/physiology
- TRPV Cation Channels/drug effects
- TRPV Cation Channels/physiology
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Affiliation(s)
- R G Pertwee
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
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Abstract
To date, two cannabinoid receptors have been isolated by molecular cloning. The CB1 and CB2 cannabinoid receptors are members of the G protein-coupled receptor family. There is also evidence for additional cannabinoid receptor subtypes. The CB1 and CB2 receptors recognize endogenous and exogenous cannabinoid compounds, which fall into five structurally diverse classes. Mutagenesis and molecular modeling studies have identified several key amino acid residues involved in the selective recognition of these ligands. Numerous residues involved in receptor activation have been elucidated. Regions of the CB1 receptor mediating desensitization and internalization have also been discovered. The known genetic structures of the CB1 and CB2 receptors indicate polymorphisms and multiple exons that maybe involved in tissue and species-specific regulation of these genes. The cannabinoid receptors are regulated during chronic agonist exposure, and gene expression is altered in disease states. There is a complex molecular architecture of the cannabinoid receptors that allows a single receptor to recognize multiple classes of compounds and produce an array of distinct downstream effects.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Drug Tolerance
- Humans
- Molecular Sequence Data
- Polymorphism, Genetic
- Protein Conformation
- Receptor, Cannabinoid, CB1/chemistry
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/physiology
- Receptor, Cannabinoid, CB2/chemistry
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/physiology
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Affiliation(s)
- M E Abood
- Forbes Norris MDA/ALS Research, California Pacific Medical Center, 2351 Clay St 416, San Francisco, CA 94115, USA.
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28
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Huffman JW, Szklennik PV, Almond A, Bushell K, Selley DE, He H, Cassidy MP, Wiley JL, Martin BR. 1-Pentyl-3-phenylacetylindoles, a new class of cannabimimetic indoles. Bioorg Med Chem Lett 2005; 15:4110-3. [PMID: 16005223 DOI: 10.1016/j.bmcl.2005.06.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 05/30/2005] [Accepted: 06/02/2005] [Indexed: 10/25/2022]
Abstract
A new class of cannabimimetic indoles, with 3-phenylacetyl or substituted 3-phenylacetyl substituents, has been prepared and their affinities for the cannabinoid CB1 and CB2 receptors have been determined. In general those compounds with a 2-substituted phenylacetyl group have good affinity for both receptors. The 4-substituted analogs have little affinity for either receptor, while the 3-substituted compounds are intermediate in their affinities. Two of these compounds, 1-pentyl-3-(2-methylphenylacetyl)indole (JWH-251) and 1-pentyl-3-(3-methoxyphenylacetyl)indole (JWH-302), have 5-fold selectivity for the CB1 receptor with modest affinity for the CB2 receptor. GTPgammaS determinations indicate that both compounds are highly efficacious agonists at the CB1 receptor and partial agonists at the CB2 receptor.
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Affiliation(s)
- John W Huffman
- Howard L. Hunter Laboratory, Clemson University, Clemson, SC 29634-0973, USA.
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29
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Abstract
After their discovery, the two known cannabinoid receptors, CB(1) and CB(2), have been the focus of research into the cellular signalling mechanisms of cannabinoids. The initial assessment, mainly derived from expression studies, was that cannabinoids, via G(i/o) proteins, negatively modulate cyclic AMP levels, and activate inward rectifying K(+) channels. Recent findings have complicated this assessment on different levels: (1) cannabinoids include a wide range of compounds with varying profiles of affinity and efficacy at the known CB receptors, and these profiles do not necessarily match their biological activity; (2) CB receptors appear to be intrinsically active and possibly coupled to more than one type of G protein; (3) CB receptor signalling mechanisms are diverse and dependent on the system studied; (4) cannabinoids have other targets than CB receptors. The aim of this mini review is to discuss the current literature regarding CB receptor signalling pathways. These include regulation of adenylyl cyclase, MAP kinase, intracellular Ca(2+), and ion channels. In addition, actions of cannabinoids that are not mediated by CB(1) or CB(2) receptors are discussed.
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Affiliation(s)
- Dirk G Demuth
- School of Life Sciences, University of Hertfordshire, CP Snow Building, Hatfield, Herts, UK
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30
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Abstract
Cannabinoid agonists such as Delta9-tetrahydrocannabinol (THC) produce a wide range of pharmacological effects both in the central nervous system and in the periphery. One of the most striking features of cannabinoids such as THC is the magnitude to tolerance that can be produced upon repetitive administration of this substance to animals. Relatively modest dosing regimens are capable of producing significant tolerance, whereas greater than 100-fold tolerance can be obtained with aggressive treatments. While cannabinoid tolerance has been studied quite extensively to establish its relevance to the health consequences of marijuana use, it has also proven to be a valuable strategy in understanding the mechanism of action of cannabinoids. The discovery of the endocannabinoid system that contains two receptor subtypes, CB1 and CB2, associated signaling pathways, endocannabinoids (anandamide and 2-arachidonoylglycerol) and their synthetic and degradative pathways has provided a means of systematically evaluating the mechanism of cannabinoid tolerance. It is well known that the CB1 cannabinoid receptor is down-regulated in states of cannabinoid tolerance along with uncoupling from its second messenger systems. Endocannabinoid levels are also altered in selected brain regions during the development of tolerance. While it is reasonable to speculate that a likely relationship exists between receptor and endocannabinoid levels, at present, little is known regarding the biological signal that leads to alterations in endocannabinoid levels. It is also unknown to what degree synthetic and degradative pathways for the endocannabinoids are altered in states of tolerance. The discovery that the brain is abundant in fatty acid amides and glycerols raises the question as to what roles these lipids contribute to the endocannabinoid system. Some of these lipids also utilize the endocannabinoid metabolic pathways, produce similar pharmacological effects, and are capable of modulating the actions of anandamide and 2-arachidonoylglycerol. In addition, there are dopamine, glycine, and serotonin conjugates of arachidonic acid that may also contribute to the actions of endocannabinoids. A systematic examination of these lipids in cannabinoid tolerance might shed light on their physiological relevance to the endocannabinoid system.
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Affiliation(s)
- Billy R Martin
- Louis and Ruth Harris Professor and Chair, Department of Pharmacology and Toxicology, P.O. Box 980613, Virginia Commonwealth University, Richmond, VA 23298, USA.
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31
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Govaerts SJ, Muccioli GG, Hermans E, Lambert DM. Characterization of the pharmacology of imidazolidinedione derivatives at cannabinoid CB1 and CB2 receptors. Eur J Pharmacol 2005; 495:43-53. [PMID: 15219819 DOI: 10.1016/j.ejphar.2004.05.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Accepted: 05/12/2004] [Indexed: 10/26/2022]
Abstract
The pharmacology of 3-(2-ethylmorpholino)-5,5'-di(p-bromophenyl)-imidazolidinedione (DML20), 3-(1-hydroxypropyl)-5,5'-di(p-bromophenyl)-imidazolidinedione (DML21) and 3-heptyl-5,5'-di(p-bromophenyl)-imidazolidinedione (DML23) was extended by studying affinity and GTP binding modulation on cannabinoid receptor subtypes (CB1 and CB2) from rat tissues and human cannabinoid receptors expressed in Chinese Hamster Ovary cells. Competitive binding studies indicated that DML20, DML21 and DML23 are selective ligands for cannabinoid CB1 receptors. In rat cerebellum homogenates, DML20, DML21 and DML23 were unable to influence [35S]GTPgammaS binding but competitively inhibit HU 210-induced [35S]GTPgammaS binding (pKB of 6.11 +/- 0.14, 6.25 +/- 0.06 and 5.74 +/- 0.09, respectively), indicating that they act as cannabinoid CB1 receptor neutral antagonists. However, in CHO cells homogenates expressing selectively either human cannabinoid CB1 or CB2 receptors, they behaved as inverse agonists decreasing the [35S]GTPgammaS binding, with similar efficacy. In conclusion, these derivatives exhibit different activities (neutral antagonism and inverse agonism) in the different models of cannabinoid receptors studied.
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MESH Headings
- Animals
- CHO Cells
- Cerebellum/drug effects
- Cerebellum/metabolism
- Cerebellum/pathology
- Cricetinae
- Cricetulus
- Drug Evaluation, Preclinical/methods
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
- Humans
- Imidazolidines/pharmacology
- Male
- Molecular Structure
- Morpholines/pharmacology
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB1/drug effects
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/drug effects
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/metabolism
- Species Specificity
- Spleen/drug effects
- Spleen/metabolism
- Spleen/pathology
- Structure-Activity Relationship
- Sulfur Radioisotopes
- Transfection/methods
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Affiliation(s)
- Sophie J Govaerts
- Unité de Chimie pharmaceutique et de Radiopharmacie (73.40) Ecole de Pharmacie, Université Catholique de Louvain, 73, Avenue E. Mounier, UCL-CMFA 7340, B-1200 Bruxelles, Belgium
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32
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Huffman JW, Zengin G, Wu MJ, Lu J, Hynd G, Bushell K, Thompson ALS, Bushell S, Tartal C, Hurst DP, Reggio PH, Selley DE, Cassidy MP, Wiley JL, Martin BR. Structure-activity relationships for 1-alkyl-3-(1-naphthoyl)indoles at the cannabinoid CB(1) and CB(2) receptors: steric and electronic effects of naphthoyl substituents. New highly selective CB(2) receptor agonists. Bioorg Med Chem 2005; 13:89-112. [PMID: 15582455 DOI: 10.1016/j.bmc.2004.09.050] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 09/28/2004] [Accepted: 09/29/2004] [Indexed: 11/21/2022]
Abstract
In an effort to improve indole-based CB(2) cannabinoid receptor ligands and also to develop SAR for both the CB(1) and CB(2) receptors, 47 indole derivatives were prepared and their CB(1) and CB(2) receptor affinities were determined. The indole derivatives include 1-propyl- and 1-pentyl-3-(1-naphthoyl)indoles both with and without a 2-methyl substituent. Naphthoyl substituents include 4- and 7-alkyl groups as well as 2-, 4-, 6-, 7-methoxy and 4-ethoxy groups. The effects of these substituents on receptor affinities are discussed and structure-activity relationships are presented. In the course of this work three new highly selective CB(2) receptor agonists were identified, 1-propyl-3-(4-methyl-1-naphthoylindole (JWH-120), 1-propyl-2-methyl-3-(6-methoxy-1-naphthoylindole (JWH-151), and 1-pentyl-3-(2-methoxy-1-naphthoylindole (JWH-267). GTPgammaS assays indicated that JWH-151 is a full agonist at CB(2), while JWH-120 and JWH-267 are partial agonists. Molecular modeling and receptor docking studies were carried out on a set of 3-(4-propyl-1-naphthoyl)indoles, a set of 3-(6-methoxy-1-naphthoyl)indoles and the pair of N-pentyl-3-(2-methoxy-1-naphthoyl)indoles. Docking studies indicated that the CB(1) receptor affinities of these compounds were consistent with their aromatic stacking interactions in the aromatic microdomain of the CB(1) receptor.
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MESH Headings
- Alkylation
- Animals
- Binding, Competitive
- CHO Cells
- Cricetinae
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Indoles/chemistry
- Indoles/metabolism
- Indoles/pharmacology
- Magnetic Resonance Spectroscopy
- Mass Spectrometry
- Models, Molecular
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/metabolism
- Structure-Activity Relationship
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Affiliation(s)
- John W Huffman
- Howard L. Hunter Laboratory, Clemson University, Clemson, SC 29634-0973, USA.
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33
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Abstract
CB(1) receptor cellular signal transduction is dependent on the expression of G proteins to which the receptor couples, the potential for precoupling of particular G proteins to the receptors either by scaffolding mechanisms or colocalization in lipid raft domains, and the effector mechanisms that these transducer molecules regulate. This discourse will evaluate studies of efficacy for CB(1) receptor-Gi/o activation at the molecular level. Evidence for brain regional differences in CB(1) receptor signal transduction efficacy and agonist selectivity for G proteins will be summarized. The possibility that CB(1) receptors interact with Gs or Gq will be evaluated, and questions with regard to the constitutive activity and G protein sequestration will be posed.
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Affiliation(s)
- Allyn C Howlett
- Neuroscience of Drug Abuse Research Program, Biomedical/Biotechnology Research Institute, 700 George Street, North Carolina Central University, Durham, NC 27707, USA.
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34
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Howlett AC, Breivogel CS, Childers SR, Deadwyler SA, Hampson RE, Porrino LJ. Cannabinoid physiology and pharmacology: 30 years of progress. Neuropharmacology 2004; 47 Suppl 1:345-58. [PMID: 15464149 DOI: 10.1016/j.neuropharm.2004.07.030] [Citation(s) in RCA: 372] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 07/23/2004] [Accepted: 07/23/2004] [Indexed: 10/26/2022]
Abstract
Delta9-Tetrahydrocannabinol from Cannabis sativa is mimicked by cannabimimetic analogs such as CP55940 and WIN55212-2, and antagonized by rimonabant and SR144528, through G-protein-coupled receptors, CB1 in the brain, and CB2 in the immune system. Eicosanoids anandamide and 2-arachidonoylglycerol are the "endocannabinoid" agonists for these receptors. CB1 receptors are abundant in basal ganglia, hippocampus and cerebellum, and their functional activity can be mapped during behaviors using cerebral metabolism as the neuroimaging tool. CB1 receptors couple to G(i/o) to inhibit cAMP production, decrease Ca2+ conductance, increase K+ conductance, and increase mitogen-activated protein kinase activity. Functional activation of G-proteins can be imaged by [35S]GTPgammaS autoradiography. Post-synaptically generated endocannabinoids form the basis of a retrograde signaling mechanism referred to as depolarization-induced suppression of inhibition (DSI) or excitation (DSE). Under circumstances of sufficient intracellular Ca2+ (e.g., burst activity in seizures), synthesis of endocannabinoids releases a diffusible retrograde messenger to stimulate presynaptic CB1 receptors. This results in suppression of gamma-aminobutyric acid (GABA) release, thereby relieving the post-synaptic inhibition. Tolerance develops as neurons adjust both receptor number and cellular signal transduction to the chronic administration of cannabinoid drugs. Future therapeutic drug design can progress based upon our current understanding of the physiology and pharmacology of CB1, CB2 and related receptors. One very important role for CB1 antagonists will be in the treatment of craving in the disease of substance abuse.
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Affiliation(s)
- Allyn C Howlett
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA.
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35
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Odagaki Y, Yamauchi T. Gamma-hydroxybutyric acid, unlike gamma-aminobutyric acid, does not stimulate Gi/Go proteins in rat brain membranes. Basic Clin Pharmacol Toxicol 2004; 94:89-98. [PMID: 14748852 DOI: 10.1111/j.1742-7843.2004.pto940206.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
gamma-Hydroxybutyric acid is a naturally occurring substance that may act as a neurotransmitter or neuromodulator to elicit several biological effects. Although the existence of a specific gamma-hydroxybutyric acid receptor has been postulated, the receptor protein itself has not been cloned yet. The current study was designed to elucidate whether gamma-hydroxybutyric acid receptors are functionally coupled with heterotrimeric G-proteins, especially Gi/Go family, by means of high-affinity GTPase activity and guanosine 5'-O-(3-[35S]thiotriphosphate) ([35S]GTPgammaS) binding assays in rat brain membranes. The stimulatory effects of GABAB receptor activation were always determined in parallel as a positive control. The selective GABAB receptor agonist (+/-)-baclofen stimulated the high-affinity GTPase activity in cerebral cortical, hippocampal, and striatal membranes, whereas gamma-hydroxybutyric acid was inactive up to 1 mM in these brain regions. The optimum assay conditions for [35S]GTPgammaS binding to detect a receptor-mediated activation of G-proteins at the greatest signal to noise ratio were then probed as to the concentrations of constituents in the assay mixture (GDP, MgCl2, and NaCl) and incubation period. Even under such an optimized experimental condition, [35S]GTPgammaS binding was not altered by gamma-hydroxybutyric acid in the membranes prepared from cerebral cortex or hippocampus. On the other hand, the specific [35S]GTPgammaS binding was increased by GABAB receptor agonists in a concentration-dependent manner, which was competitively inhibited by CGP54626, a selective GABAB receptor antagonist. These results indicate that gamma-hydroxybutyric acid receptors, if any, are not associated with G-proteins, at least Gi/Go family.
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Affiliation(s)
- Yuji Odagaki
- Department of Psychiatry, Saitama Medical School, Saitama, Japan.
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36
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Hampson RE, Simeral JD, Kelly EJ, Deadwyler SA. Tolerance to the memory disruptive effects of cannabinoids involves adaptation by hippocampal neurons. Hippocampus 2003; 13:543-56. [PMID: 12921345 DOI: 10.1002/hipo.10081] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effects of chronic exposure to cannabinoids on short-term memory in rats were assessed during repeated daily injections of an initially debilitating dose (3.75 mg/kg) of the potent CB1 cannabinoid receptor ligand, WIN 55,212-2. Delayed nonmatch to sample (DNMS) performance was assessed over a 35-day exposure period in which performance was initially disrupted during the first 21 days of exposure but recovered by day 30 and was stable at pre-drug levels for 5 days thereafter. Withdrawal was precipitated by injections of the CB1 receptor antagonist SR141716A and transiently reduced performance for 2 days but was restabilized to pre-drug levels within 3-4 days. Concomitant recording from identified CA1 and CA3 hippocampal neurons demonstrated a marked correspondence in the time course of suppression of peak firing in the sample and delay phases of the task to the drug-induced performance deficits over the same days of exposure. Hippocampal encoding of task-relevant events and performance levels "tracked" each other on a daily basis throughout the chronic cannabinoid treatment and withdrawal regimen. However, hippocampal neuronal activity in the nonmatch phase of the task was unaffected by the chronic cannabinoid treatment or withdrawal, suggesting that only a select population of hippocampal neurons and synapses are involved in cannabinoid-sensitive short-term memory processes.
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Affiliation(s)
- Robert E Hampson
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1083, USA.
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37
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Ruiu S, Pinna GA, Marchese G, Mussinu JM, Saba P, Tambaro S, Casti P, Vargiu R, Pani L. Synthesis and characterization of NESS 0327: a novel putative antagonist of the CB1 cannabinoid receptor. J Pharmacol Exp Ther 2003; 306:363-70. [PMID: 12663689 DOI: 10.1124/jpet.103.049924] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The compound N-piperidinyl-[8-chloro-1-(2,4-dichlorophenyl)-1,4,5,6-tetrahydrobenzo [6,7]cyclohepta[1,2-c]pyrazole-3-carboxamide] (NESS 0327) was synthesized and evaluated for binding affinity toward cannabinoid CB1 and CB2 receptor. NESS 0327 exhibited a stronger selectivity for CB1 receptor compared with N-piperidinyl-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR 141716A), showing a much higher affinity for CB1 receptor (Ki = 350 +/- 5 fM and 1.8 +/- 0.075 nM, respectively) and a higher affinity for the CB2 receptor (Ki = 21 +/- 0.5 nM and 514 +/- 30 nM, respectively). Affinity ratios demonstrated that NESS 0327 was more than 60,000-fold selective for the CB1 receptor, whereas SR 141716A only 285-fold. NESS 0327 alone did not produce concentration-dependent stimulation of guanosine 5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS) binding in rat cerebella membranes. Conversely, NESS 0327 antagonized [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrolol [1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate] (WIN 55,212-2)-stimulated [35S]GTPgammaS binding. In functional assay, NESS 0327 antagonized the inhibitory effects of WIN 55,212-2 on electrically evoked contractions in mouse isolated vas deferens preparations with pA2 value of 12.46 +/- 0.23. In vivo studies indicated that NESS 0327 antagonized the antinociceptive effect produced by WIN 55,212-2 (2 mg/kg s.c.) in both tail-flick (ID50 = 0.042 +/- 0.01 mg/kg i.p.) and hot-plate test (ID50 = 0.018 +/- 0.006 mg/kg i.p.). These results indicated that NESS 0327 is a novel cannabinoid antagonist with high selectivity for the cannabinoid CB1 receptor.
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Affiliation(s)
- Stefania Ruiu
- Institute of Neurogenetic and Neuropharmacology, Via Boccaccio 8, 09047 Selargius, Italy.
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38
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Abstract
Research of cannabinoid actions was boosted in the 1990s by remarkable discoveries including identification of endogenous compounds with cannabimimetic activity (endocannabinoids) and the cloning of their molecular targets, the CB1 and CB2 receptors. Although the existence of an endogenous cannabinoid signaling system has been established for a decade, its physiological roles have just begun to unfold. In addition, the behavioral effects of exogenous cannabinoids such as delta-9-tetrahydrocannabinol, the major active compound of hashish and marijuana, await explanation at the cellular and network levels. Recent physiological, pharmacological, and high-resolution anatomical studies provided evidence that the major physiological effect of cannabinoids is the regulation of neurotransmitter release via activation of presynaptic CB1 receptors located on distinct types of axon terminals throughout the brain. Subsequent discoveries shed light on the functional consequences of this localization by demonstrating the involvement of endocannabinoids in retrograde signaling at GABAergic and glutamatergic synapses. In this review, we aim to synthesize recent progress in our understanding of the physiological roles of endocannabinoids in the brain. First, the synthetic pathways of endocannabinoids are discussed, along with the putative mechanisms of their release, uptake, and degradation. The fine-grain anatomical distribution of the neuronal cannabinoid receptor CB1 is described in most brain areas, emphasizing its general presynaptic localization and role in controlling neurotransmitter release. Finally, the possible functions of endocannabinoids as retrograde synaptic signal molecules are discussed in relation to synaptic plasticity and network activity patterns.
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Affiliation(s)
- Tamas F Freund
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest 8, Szigony u.43, H-1083 Hungary.
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39
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Feng W, Song ZH. Effects of D3.49A, R3.50A, and A6.34E mutations on ligand binding and activation of the cannabinoid-2 (CB2) receptor. Biochem Pharmacol 2003; 65:1077-85. [PMID: 12663043 DOI: 10.1016/s0006-2952(03)00005-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In several G protein-coupled receptors (GPCRs), the Asp-Arg-Tyr (DRY) motif at the bottom of third transmembrane domain and the amino acid at position 6.34 in the sixth transmembrane domain have been shown to play important roles in signal transduction. In this study, we propose that in the cannabinoid-2 (CB2) receptor, R3.50 in the DRY motif may be crucial for interacting with G proteins, and D3.49 and A6.34 may be important for constraining the receptor in an inactive conformation. To test our hypothesis, R3.50A, D3.49A, and A6.34E mutations of the human CB2 receptor were made by site-directed mutagenesis. These mutant receptors were stably transfected into human embryonic 293 cells, and their ligand binding and signal transduction properties were analyzed. Similar to other GPCRs, R3.50 of the CB2 receptor is crucial for signal transduction. Unlike other GPCRs, D3.49 and A6.34 of the CB2 receptor do not seem to be important for keeping the receptor in an inactive state. Furthermore, D3.49A and A6.34E mutations abolished ligand binding, and all three mutations abolished constitutive activity of the wild-type CB2 receptor.
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Affiliation(s)
- Wenke Feng
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40292, USA
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40
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Sim-Selley LJ, Vogt LJ, Vogt BA, Childers SR. Cellular localization of cannabinoid receptors and activated G-proteins in rat anterior cingulate cortex. Life Sci 2002; 71:2217-26. [PMID: 12215369 DOI: 10.1016/s0024-3205(02)02017-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cannabinoid receptors are found in moderate density throughout the cerebral cortex. The anterior cingulate cortex (ACC) is of particular interest due its high level of cannabinoid receptors and role in behaviors known to be modulated by cannabinoids. These studies were conducted to determine the cellular localization of cannabinoid receptors and to compare the level of cannabinoid receptor binding with receptor-mediated G-protein activity in the rat ACC. Either ibotenic acid or undercut lesions were made in ACC, and brains were processed for [3H]WIN 55,212-2 and WIN 55,212-2-stimulated [35S]GTPgammaS autoradiography. Both cannabinoid receptors and receptor-activated G-proteins were highest in laminae I and VI of ACC in control tissue. Although similar levels of receptor binding were found in these laminae, significantly higher levels of receptor-activated G-proteins were found in lamina VI. Ibotenic acid lesions that destroyed ACC neurons decreased [3H]WIN 55,212-2 binding by 60-70% and eliminated WIN 55,212-2-stimulated [35S]GTPgammaS binding. In contrast, deafferentation of the ACC with undercut lesions had no significant effect on cannabinoid receptor binding or G-protein activation. These results indicate that cannabinoid receptors in laminae I and VI of the ACC are located on somatodendritic elements or axons intrinsic to the ACC. In addition, differences in the relative levels of cannabinoid binding sites and activated G-proteins between cortical laminae indicate that the efficiency of cannabinoid receptors for G-protein activation may vary within a specific brain region.
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Affiliation(s)
- Laura J Sim-Selley
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies, Box 980524, Virginia Commonwealth University Medical College of Virginia, Richmond, VA 23298, USA.
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41
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McAllister SD, Glass M. CB(1) and CB(2) receptor-mediated signalling: a focus on endocannabinoids. Prostaglandins Leukot Essent Fatty Acids 2002; 66:161-71. [PMID: 12052033 DOI: 10.1054/plef.2001.0344] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The discovery that the major psychoactive component of marijuana activated two G-protein coupled receptors prompted the search for the endogenous cannabinoid ligands now termed endocannabinoids. To date three putative ligands have been isolated, all consisting of arachidonic acid linked to a polar head group. Both synthetic and endogenous cannabinoids have been the focus of extensive study over the past few years. The signalling events produced by endocannabinoids as compared with Delta(9) -THC and synthetic cannabinoids contain many similarities. However, as research focuses more on endogenous ligands the divergence between these classes of compounds grows. This review focuses upon the developments in endocannabinoid signal transduction from receptor-mediated activation of common G-protein linked effector pathways through downstream regulation of gene transcription.
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Affiliation(s)
- Sean D McAllister
- Forbes Norris ALS Research Center, California Pacific Medical Centre, 2351 Clay Street, Suite 416, San Francisco, CA 94115, USA
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Savinainen JR, Järvinen T, Laine K, Laitinen JT. Despite substantial degradation, 2-arachidonoylglycerol is a potent full efficacy agonist mediating CB(1) receptor-dependent G-protein activation in rat cerebellar membranes. Br J Pharmacol 2001; 134:664-72. [PMID: 11588122 PMCID: PMC1572991 DOI: 10.1038/sj.bjp.0704297] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. Two endocannabinoids, arachidonoyl ethanolamide (AEA) and 2-arachidonoylglycerol (2-AG) bind and activate G-protein-coupled cannabinoid receptors, but limited data exist on their relative ability to activate G-proteins. 2. Here we assess agonist potency and efficacy of various cannabinoids, including 2-AG, HU-310 (2-arachidonoyl glyceryl ether, a third putative endocannabinoid), HU-313 (another ether analogue of 2-AG), AEA, R-methanandamide (an enzymatically stable analogue of AEA), and CP-55,940 at rat brain CB(1) receptors using agonist-stimulated [(35)S]-GTPgammaS binding to cerebellar membranes and whole brain sections. Degradation of endocannabinoids under experimental conditions was monitored by HPLC. 3. To enhance efficacy differences, agonist dose-response curves were generated using increasing GDP concentrations. At 10(-6) M GDP, all compounds, except HU-313, produced full agonists responses approximately 2.5 fold over basal. The superior efficacy of 2-AG over all other compounds became evident by increasing GDP (10(-5) and 10(-4) M). 4. In membrane incubations, 2-AG was degraded by 85% whereas AEA and HU-310 were stable. Pretreatment of membranes with phenylmethylsulphonyl fluoride inhibited 2-AG degradation, resulting in 2 fold increase in agonist potency. Such pretreatment had no effect on AEA potency. 5. Responses in brain sections were otherwise consistent with membrane binding data, but 2-AG evoked only a weak signal in brain sections, apparently due to more extensive degradation. 6. These data establish that even under conditions of substantial degradation, 2-AG is a full efficacy agonist, clearly more potent than AEA, in mediating CB(1) receptor-dependent G-protein activity in native membranes.
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Selley DE, Rorrer WK, Breivogel CS, Zimmer AM, Zimmer A, Martin BR, Sim-Selley LJ. Agonist efficacy and receptor efficiency in heterozygous CB1 knockout mice: relationship of reduced CB1 receptor density to G-protein activation. J Neurochem 2001; 77:1048-57. [PMID: 11359870 DOI: 10.1046/j.1471-4159.2001.00308.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Heterozygous CB1 receptor knockout mice were used to examine the effect of reduced CB1 receptor density on G-protein activation in membranes prepared from four brain regions: cerebellum, hippocampus, striatum/globus pallidus (striatum/GP) and cingulate cortex. Results showed that CB1 receptor levels were approximately 50% lower in heterozygous mice in all regions examined. However, maximal stimulation of [(35)S]guanosine-5'-(gamma-O-thio) triphosphate ([(35)S]GTPgammaS) binding by the high efficacy agonist WIN 55,212-2 was reduced by only 20-25% in most brain regions, with the exception of striatum/GP where the decrease in stimulation was as predicted (approximately 50%). Furthermore, although the efficacies of the cannabinoid partial agonists, methanandamide and (9)-tetrahydrocannabinol, were similarly lower in heterozygous mice, their relative efficacies compared with WIN 55,212-2 were generally unchanged. Saturation analysis of net WIN 55,212-2-stimulated [(35)S]GTPgammaS binding showed that decreased stimulation by WIN 55,212-2 in striatum/GP of heterozygous mice was caused by a decrease in the apparent affinity of net-stimulated [(35)S]GTPgammaS binding. The apparent maximal number of binding sites (B(max)) values of net WIN 55,212-2-stimulated [(35)S]GTPgammaS binding were unchanged in cerebellum and striatum/GP of heterozygous mice, but decreased in cingulate cortex, with a similar trend in hippocampus. Moreover, in every region except cingulate cortex, the maximal number of net-stimulated [(35)S]GTPgammaS binding sites per receptor was significantly increased in heterozygous mice. These results indicate region-dependent increases in the apparent efficiency of CB1 receptor-mediated G-protein activation in heterozygous CB1 knockout mice.
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Affiliation(s)
- D E Selley
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia, USA.
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Basavarajappa BS, Hungund BL. Cannabinoid receptor agonist-stimulated [35S]guanosine triphosphate gammaS binding in the brain of C57BL/6 and DBA/2 mice. J Neurosci Res 2001; 64:429-36. [PMID: 11340650 DOI: 10.1002/jnr.1094] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The two inbred strains of mice C57BL/6 (alcohol-preferring) and DBA/2 (alcohol-avoiding) mice have been shown to differ significantly in their preference for alcohol (EtOH). We have previously demonstrated the differences in the density and the affinity of cannabinoid (CB1) receptors in the brains of the two inbred C57BL/6 and DBA/2 mouse strains. In the present study, we investigated the CB1 receptor agonist-stimulated guanosine-5'-O-(3-[(35)S]thio)-triphosphate ([(35)S]GTPgammaS) binding in plasma membranes (PM) from C57BL/6 and DBA/2 mice. The results indicate that the net CP55,940-stimulated [(35)S]GTPgammaS binding was increased with increasing concentrations of CB1 receptor agonists and GDP. The net CB1 receptor agonist (WIN55,212-2 or HU-210 or CP55,940)-stimulated [(35)S]GTPgammaS binding was reduced significantly (-10% to -12%, P < 0.05) in PM from DBA/2 mice; no significant differences were observed in basal [(35)S]GTPgammaS binding among these strains. Nonlinear regression analysis of net CP55,940-stimulated [(35)S]GTPgammaS binding showed that the B(max) of cannabinoid agonist-stimulated binding was significantly reduced (-24%) in DBA/2 mice (B(max) = 12.43 +/- 0.64 for C57BL/6 and 9.46 +/- 0.98 pmol/mg protein for DBA/2; P < 0.05) without any significant changes in the G protein affinity. The pharmacological specificity of CP55,940-stimulated [(35)S]GTPgammaS binding was examined with CB1 receptor antagonist SR141716A, and these studies indicated that CP55,940-stimulated [(35)S]GTPgammaS binding was blocked by SR141716A, with a decrease in the IC(50) values in the PM from the DBA/2 mouse strain. These results suggest that a signal transduction pathway(s) downstream from the CB1 receptor system may play an important role in controlling the voluntary EtOH consumption by these strains of mice.
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Affiliation(s)
- B S Basavarajappa
- New York State Psychiatric Institute at NKI, Orangeburg, New York 10962, USA
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45
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Ross RA, Coutts AA, McFarlane SM, Anavi-Goffer S, Irving AJ, Pertwee RG, MacEwan DJ, Scott RH. Actions of cannabinoid receptor ligands on rat cultured sensory neurones: implications for antinociception. Neuropharmacology 2001; 40:221-32. [PMID: 11114401 DOI: 10.1016/s0028-3908(00)00135-0] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cannabinoids modulate nociceptive processing in models of acute, inflammatory and neuropathic pain. We have investigated the location and function of cannabinoid receptors on cultured neonatal dorsal root ganglion (DRG) neurones and F-11 cells, a dorsal root ganglionxneuroblastoma hybridoma which displays several of the features of authentic DRG neurones. CB(1) receptor immunolabelling was observed on the cell bodies and as fine puncta on processes of both cultured DRG neurones and F-11 cells. Additionally, fluorescence-activated cell sorting (FACS) analysis provided evidence that both CB(1) and CB(2) receptors are expressed on populations of cells within the cultured DRG and F-11 cells. The cannabinoid receptor agonist (+)-WIN55212 (10 and 100 nM) inhibited the mean voltage-activated Ca(2+) current in DRG neurones by 21% and 30%, respectively. The isomer, (-)-WIN55212 (10 and 100 nM) produced significantly less inhibition of 6% and 10% respectively. The CB(1) selective receptor antagonist SR141716A (100 nM) enhanced the peak high voltage-activated Ca(2+) current by 24% and simultaneous application of SR141716A (100 nM) and (+)-WIN55212 (100 nM) resulted in a significant attenuation of the inhibition obtained with (+)-WIN55212 alone. These data give functional evidence for the hypothesis that the analgesic actions of cannabinoids may be mediated by presynaptic inhibition of transmitter release in sensory neurones.
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MESH Headings
- Animals
- Animals, Newborn
- Benzoxazines
- Calcium Channel Blockers/pharmacology
- Calcium Channels/physiology
- Cannabinoids/metabolism
- Cells, Cultured
- Colforsin/pharmacology
- Cyclic AMP/biosynthesis
- Fluorescence
- Ganglia, Spinal/cytology
- Immunohistochemistry
- Ion Channel Gating
- Ligands
- Morpholines/pharmacology
- Naphthalenes/pharmacology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Patch-Clamp Techniques
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB2
- Receptors, Cannabinoid
- Receptors, Drug/drug effects
- Receptors, Drug/metabolism
- Receptors, Drug/physiology
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Affiliation(s)
- R A Ross
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
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46
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Sim-Selley LJ, Brunk LK, Selley DE. Inhibitory effects of SR141716A on G-protein activation in rat brain. Eur J Pharmacol 2001; 414:135-43. [PMID: 11239913 DOI: 10.1016/s0014-2999(01)00784-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A), a cannabinoid CB(1) receptor antagonist, has inverse agonist effects in cannabinoid CB(1) receptor-expressing cell lines, brain and peripheral organs. These studies characterized SR141716A-inhibited G-protein activity by measuring [35S]GTPgammaS binding. Maximal inhibition of basal [35S]GTPgammaS binding in cerebellar membranes was 50%. The EC(50) value for inhibition of [35S]GTPgammaS binding was 4.4 microM, whereas the K(e) for inhibition of R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone mesylate (WIN 55,212-2)-stimulated [35S]GTPgammaS binding was 0.6 nM. [35S]GTPgammaS autoradiography was used to examine the regional specificity of SR141716A inhibition. SR141716A inhibited basal [35S]GTPgammaS binding in all regions examined, with inhibition ranging from approximately 20% in caudate-putamen to 40% in hippocampus. These studies demonstrate that SR141716A is a competitive antagonist at nanomolar concentrations, whereas it inhibits basal receptor-mediated G-protein activity at micromolar concentrations. These data suggest that the apparent inverse agonist effect is either not cannabinoid CB(1) receptor-specific or that SR141716A is binding to different sites on the cannabinoid CB(1) receptor to produce inverse agonist versus competitive antagonist effects.
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Affiliation(s)
- L J Sim-Selley
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies, Virginia Commonwealth University Medical College of Virginia, 1112 East Clay St., Box 980524, 23298, Richmond, VA, USA.
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47
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Cheer JF, Marsden CA, Kendall DA, Mason R. Lack of response suppression follows repeated ventral tegmental cannabinoid administration: an in vitro electrophysiological study. Neuroscience 2001; 99:661-7. [PMID: 10974429 DOI: 10.1016/s0306-4522(00)00241-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cannabinoid compounds have been reported to excite ventral tegmental neurons through activation of cannabinoid CB1 receptors. More recently, biochemical and whole-cell voltage-clamp studies carried out on CB1-transfected AtT20 cells have shown a rapid desensitization of these receptors following activation of protein kinase C by 4-alpha-phorbol. To investigate the possible physiological correlates of this phenomenon, we have studied the effects of repeated cannabinoid treatment on ventral tegmental area dopaminergic neuronal firing in vitro. Rat brain slices containing the ventral tegmental area were used for single-unit extracellular recordings. Only neurons meeting established electrophysiological and pharmacological criteria for dopaminergic neurons were used in the study (firing neurons were detected either using tungsten or glass microelectrodes). The high-affinity cannabinoid agonist HU210 produced a concentration-dependent increase in firing (1-15 microM; EC(50) approximately 7 microM). Initial HU210 exposure produced a significant increase in cell firing rate in the ventral tegmental area, with a maximum approximately 3.5-fold increase over pre-drug basal firing; a subsequent exposure to HU210 produced an approximately threefold increase over basal firing. Nevertheless, the duration and onset of excitation produced by the cannabinoid differed significantly between the first and second exposures; the first excitation lasted significantly longer than the second and required less time to reach a comparable change in firing rate. The increases in firing rate and the time to return to basal firing were not significantly different between exposures. Furthermore, the cannabinoid antagonist SR141716A completely prevented the HU210-induced excitation whilst having no effect on its own, thus indicating a CB1-receptor mediated mechanism for the observed increase in firing. Ventral tegmental area neurons are also excited by the GABA(A) receptor antagonist bicuculline. To assess the role of GABA in cannabinoid-mediated excitation, HU210 was added in the presence of bicuculline. HU210 did not affect the initial bicuculline-induced increase in firing, suggesting different sites of action for the two compounds. Our data fail to support previously reported findings using repeated cannabinoid administration and cell preparations. The maintained increase in DA drive elicited by the potent cannabinoid agonist HU210 in the in vitro ventral tegmental circuit could explain some of the behavioural properties of cannabinoids, such as the lack of tolerance for the psychotropic effects of marijuana seen in human users.
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Affiliation(s)
- J F Cheer
- School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, NG7 2UH, Nottingham, UK.
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Griffin G, Williams S, Aung MM, Razdan RK, Martin BR, Abood ME. Separation of cannabinoid receptor affinity and efficacy in delta-8-tetrahydrocannabinol side-chain analogues. Br J Pharmacol 2001; 132:525-35. [PMID: 11159703 PMCID: PMC1572574 DOI: 10.1038/sj.bjp.0703827] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The activities of a number of side-chain analogues of delta-8-tetrahydrocannabinol (Delta(8)-THC) in rat cerebellar membrane preparations were tested. 2. The affinities of each compound for the CB(1) receptor were compared by their respective abilities to displace [(3)H]-SR141716A and their efficacies compared by stimulation of [(35)S]-GTPgammaS binding. 3. It was found that the affinities varied from 0.19+/-0.03 nM for 3-norpentyl-3-[6'-cyano,1',1'-dimethyl]hexyl-Delta(8)-THC to 395+/-66.3 nM for 5'-[N-(4-chlorophenyl)]-1',1'-dimethyl-carboxamido-Delta(8)-THC. 4. The efficacies of these compounds varied greatly, ranging from the very low efficacy exhibited to acetylenic compounds such as 1'-heptyn-Delta(8)-THC and 4'-octyn-Delta(8)-THC to higher efficacy compounds such as 5'-(4-cyanophenoxy)-1',1'-dimethyl-Delta(8)-THC and 5'-[N-(4-aminosulphonylphenyl)]-1',1' dimethyl-carboxamido Delta(8)-THC. All agonist activities were antagonized by the CB(1)-selective antagonist SR141716A. 5. It was found that a ligand's CB(1) affinity and efficacy are differentially altered by modifications in the side-chain. Decreasing the flexibility of the side-chain reduced efficacy but largely did not alter affinity. Additionally, the positioning of electrostatic moieties, such as cyano groups, within the side-chain also has contrasting effects on these two properties. 6. In summary, this report details the characterization of a number of novel Delta(8)-THC analogues in rat cerebellar membranes. It provides the first detailed pharmacological analysis of how the inclusion of electrostatic moieties in the side-chain and also how alteration of the side-chain's flexibility may differentially affect a CB(1) cannabinoid receptor ligand's affinity and efficacy.
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Affiliation(s)
- G Griffin
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, VA 23298, USA
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49
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He L, Di Monte DA, Langston JW, Quik M. Autoradiographic analysis of dopamine receptor-stimulated [(35)S]GTPgammaS binding in rat striatum. Brain Res 2000; 885:133-6. [PMID: 11121540 DOI: 10.1016/s0006-8993(00)02981-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autoradiographic analysis of [(35)S]GTPgammaS binding was used to investigate functional activation of dopamine receptors in rat striatum. Dopamine-stimulated [(35)S]GTPgammaS binding was observed with a maximal increase of 38% over basal activity. A similar stimulatory response was obtained with the D(2) agonist quinpirole, but not SKF-238393, a D(1) agonist. The effect of dopamine was blocked by the D(2) antagonist raclopride, but was unaffected by SCH-23990, a D(1) antagonist. There appeared to be a differential distribution of dopamine-stimulated [(35)S]GTPgammaS binding, with the lowest activity obtained in the medial portion of the caudal striatum. These results demonstrate, using an autoradiographic approach, (i) that dopamine stimulated [(35)S]GTPgammaS binding in the rat striatum occurs through activation of D(2) receptors, and (ii) that the effects of dopamine activation vary in different areas of the rat striatum.
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Affiliation(s)
- L He
- The Parkinson's Institute, 1170 Morse Avenue, Sunnyvale, CA 94089, USA
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50
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Hillard CJ. Biochemistry and pharmacology of the endocannabinoids arachidonylethanolamide and 2-arachidonylglycerol. Prostaglandins Other Lipid Mediat 2000; 61:3-18. [PMID: 10785538 DOI: 10.1016/s0090-6980(00)00051-4] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The purpose of this review is to discuss the cellular synthesis and inactivation of two putative endogenous ligands of the cannabinoid receptor, N-arachidonylethanolamine (AEA) and 2-arachidonylglycerol (2-AG). Both ligands are synthesized by neurons and brain tissue in response to increased intracellular calcium concentrations. Both ligands are substrates for fatty acid amide hydrolase (FAAH). Both AEA and 2-AG bind to the neuronal form of the cannabinoid receptor (CB1). AEA binds the receptor with moderate affinity and has the characteristics of a partial agonist, whereas, 2-AG binds with low affinity but exhibits full efficacy. Two possible physiological roles of the endocannabinoids and the CB1 receptor are discussed: the regulation of gestation and the regulation of gastrointestinal motility.
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Affiliation(s)
- C J Hillard
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, USA.
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