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Piscura MK, Henderson-Redmond AN, Barnes RC, Mitra S, Guindon J, Morgan DJ. Mechanisms of cannabinoid tolerance. Biochem Pharmacol 2023; 214:115665. [PMID: 37348821 PMCID: PMC10528043 DOI: 10.1016/j.bcp.2023.115665] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 06/24/2023]
Abstract
Cannabis has been used recreationally and medically for centuries, yet research into understanding the mechanisms of its therapeutic effects has only recently garnered more attention. There is evidence to support the use of cannabinoids for the treatment of chronic pain, muscle spasticity, nausea and vomiting due to chemotherapy, improving weight gain in HIV-related cachexia, emesis, sleep disorders, managing symptoms in Tourette syndrome, and patient-reported muscle spasticity from multiple sclerosis. However, tolerance and the risk for cannabis use disorder are two significant disadvantages for cannabinoid-based therapies in humans. Recent work has revealed prominent sex differences in the acute response and tolerance to cannabinoids in both humans and animal models. This review will discuss evidence demonstrating cannabinoid tolerance in rodents, non-human primates, and humans and our current understanding of the neuroadaptations occurring at the cannabinoid type 1 receptor (CB1R) that are responsible tolerance. CB1R expression is downregulated in tolerant animals and humans while there is strong evidence of CB1R desensitization in cannabinoid tolerant rodent models. Throughout the review, critical knowledge gaps are indicated and discussed, such as the lack of a neuroimaging probe to assess CB1R desensitization in humans. The review discusses the intracellular signaling pathways that are responsible for mediating CB1R desensitization and downregulation including the action of G protein-coupled receptor kinases, β-arrestin2 recruitment, c-Jun N-terminal kinases, protein kinase A, and the intracellular trafficking of CB1R. Finally, the review discusses approaches to reduce cannabinoid tolerance in humans based on our current understanding of the neuroadaptations and mechanisms responsible for this process.
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Affiliation(s)
- Mary K Piscura
- Department of Biomedical Sciences, Marshall University, Huntington, WV 25755, USA; Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Auburn, AL 36832, USA
| | | | - Robert C Barnes
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Swarup Mitra
- Department of Biomedical Sciences, Marshall University, Huntington, WV 25755, USA
| | - Josée Guindon
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Daniel J Morgan
- Department of Biomedical Sciences, Marshall University, Huntington, WV 25755, USA.
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2
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Leo LM, Abood ME. CB1 Cannabinoid Receptor Signaling and Biased Signaling. Molecules 2021; 26:molecules26175413. [PMID: 34500853 PMCID: PMC8433814 DOI: 10.3390/molecules26175413] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 12/11/2022] Open
Abstract
The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling—the preferential activation of a signaling transducer in detriment of another—have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.
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Haspula D, Clark MA. Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases. Int J Mol Sci 2020; 21:E7693. [PMID: 33080916 PMCID: PMC7590033 DOI: 10.3390/ijms21207693] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/16/2022] Open
Abstract
The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.
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Affiliation(s)
- Dhanush Haspula
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA;
| | - Michelle A. Clark
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33314, USA
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4
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Kesner AJ, Lovinger DM. Cannabinoids, Endocannabinoids and Sleep. Front Mol Neurosci 2020; 13:125. [PMID: 32774241 PMCID: PMC7388834 DOI: 10.3389/fnmol.2020.00125] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022] Open
Abstract
Sleep is a vital function of the nervous system that contributes to brain and bodily homeostasis, energy levels, cognitive ability, and other key functions of a variety of organisms. Dysfunctional sleep induces neural problems and is a key part of almost all human psychiatric disorders including substance abuse disorders. The hypnotic effects of cannabis have long been known and there is increasing use of phytocannabinoids and other formulations as sleep aids. Thus, it is crucial to gain a better understanding of the neurobiological basis of cannabis drug effects on sleep, as well as the role of the endogenous cannabinoid system in sleep physiology. In this review article, we summarize the current state of knowledge concerning sleep-related endogenous cannabinoid function derived from research on humans and rodent models. We also review information on acute and chronic cannabinoid drug effects on sleep in these organisms, and molecular mechanisms that may contribute to these effects. We point out the potential benefits of acute cannabinoids for sleep improvement, but also the potential sleep-disruptive effects of withdrawal following chronic cannabinoid drug use. Prescriptions for future research in this burgeoning field are also provided.
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Affiliation(s)
- Andrew J Kesner
- Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institute of Health (NIH), Bethesda, MD, United States
- Center on Compulsive Behaviors, Intramural Research Program, National Institute of Health (NIH), Bethesda, MD, United States
| | - David M Lovinger
- Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institute of Health (NIH), Bethesda, MD, United States
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5
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Fletcher-Jones A, Hildick KL, Evans AJ, Nakamura Y, Henley JM, Wilkinson KA. Protein Interactors and Trafficking Pathways That Regulate the Cannabinoid Type 1 Receptor (CB1R). Front Mol Neurosci 2020; 13:108. [PMID: 32595453 PMCID: PMC7304349 DOI: 10.3389/fnmol.2020.00108] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 05/20/2020] [Indexed: 12/29/2022] Open
Abstract
The endocannabinoid system (ECS) acts as a negative feedback mechanism to suppress synaptic transmission and plays a major role in a diverse range of brain functions including, for example, the regulation of mood, energy balance, and learning and memory. The function and dysfunction of the ECS are strongly implicated in multiple psychiatric, neurological, and neurodegenerative diseases. Cannabinoid type 1 receptor (CB1R) is the most abundant G protein-coupled receptor (GPCR) expressed in the brain and, as for any synaptic receptor, CB1R needs to be in the right place at the right time to respond appropriately to changing synaptic circumstances. While CB1R is found intracellularly throughout neurons, its surface expression is highly polarized to the axonal membrane, consistent with its functional expression at presynaptic sites. Surprisingly, despite the importance of CB1R, the interacting proteins and molecular mechanisms that regulate the highly polarized distribution and function of CB1R remain relatively poorly understood. Here we set out what is currently known about the trafficking pathways and protein interactions that underpin the surface expression and axonal polarity of CB1R, and highlight key questions that still need to be addressed.
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Affiliation(s)
- Alexandra Fletcher-Jones
- Centre for Synaptic Plasticity, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Keri L Hildick
- Centre for Synaptic Plasticity, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Ashley J Evans
- Centre for Synaptic Plasticity, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Yasuko Nakamura
- Centre for Synaptic Plasticity, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Jeremy M Henley
- Centre for Synaptic Plasticity, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Kevin A Wilkinson
- Centre for Synaptic Plasticity, School of Biochemistry, University of Bristol, Bristol, United Kingdom
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Breivogel CS, Wells JR, Jonas A, Mistry AH, Gravley ML, Patel RM, Whithorn BE, Brenseke BM. Comparison of the Neurotoxic and Seizure-Inducing Effects of Synthetic and Endogenous Cannabinoids with Δ 9-Tetrahydrocannabinol. Cannabis Cannabinoid Res 2020; 5:32-41. [PMID: 32322674 PMCID: PMC7173680 DOI: 10.1089/can.2019.0003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Introduction: Synthetic cannabinoids (SCs) are commonly found in preparations used as recreational drugs. Although severe adverse health effects are not generally associated with cannabis use, a rising number of studies document seizures and even death after SC use. In this study, a mouse model is used to investigate the hypothesis that SCs are more toxic than Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis. Materials and Methods: Beginning with the SCs, JWH-073 and AM-2201, dose–response curves were generated to find the dose of each drug that was similarly efficacious to 50 mg/kg THC. Mice were given daily intraperitoneal (IP) injections of vehicle, 50 mg/kg THC, 30 mg/kg JWH-073, or 1 mg/kg AM-2201 until tolerance to the antinociceptive and hypothermic effects was complete, and then were assessed for spontaneous and antagonist-precipitated withdrawal and potential organ damage. No differences in tolerance were noted, but AM-2201 showed more rearing in the spontaneous and antagonist-precipitated withdrawal phases than either vehicle or the other two drug treatments. Histopathological examination of these mice revealed no drug-induced lesions. In a subsequent set of experiments, various doses of THC, methanandamide (mAEA), and of a variety of SCs (HU-210, CP55940, JWH-073, AM-2201, and PB-22) were given IP, and convulsions and change in body temperature were quantified. Discussion: The treatments yielded varying numbers of convulsions and a range of changes in body temperature. JWH-073 and AM-2201 produced significantly more convulsions than THC, HU-210, mAEA, or cannabidiol (CBD) (the latter two producing none). HU-210, CP55940, JWH-073, and mAEA produced greater hypothermia than THC or CBD. Convulsions and hypothermia induced by several agonists were prevented by pretreatment with a CB1 antagonist, but not a CB2 antagonist. Conclusions: In agreement with human studies and case reports, this study found that SCs generally produced more seizures than THC. Of particular significance was the finding that mAEA produced far greater hypothermia than THC (similar to most SCs), but unlike the SCs and THC, produced no seizures.
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Affiliation(s)
- Chris S Breivogel
- Department of Pharmaceutical Sciences, Campbell University College of Pharmacy & Health Sciences, Buies Creek, North Carolina
| | - Jacob R Wells
- Department of Pharmaceutical Sciences, Campbell University College of Pharmacy & Health Sciences, Buies Creek, North Carolina
| | - Amreen Jonas
- Department of Pharmaceutical Sciences, Campbell University College of Pharmacy & Health Sciences, Buies Creek, North Carolina
| | - Artik H Mistry
- Department of Pharmaceutical Sciences, Campbell University College of Pharmacy & Health Sciences, Buies Creek, North Carolina
| | - Morgan L Gravley
- Department of Pharmaceutical Sciences, Campbell University College of Pharmacy & Health Sciences, Buies Creek, North Carolina
| | - Rajul M Patel
- School of Osteopathic Medicine, Campbell University, Buies Creek, North Carolina
| | - Brianna E Whithorn
- School of Osteopathic Medicine, Campbell University, Buies Creek, North Carolina
| | - Bonnie M Brenseke
- School of Osteopathic Medicine, Campbell University, Buies Creek, North Carolina
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7
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Al-Zoubi R, Morales P, Reggio PH. Structural Insights into CB1 Receptor Biased Signaling. Int J Mol Sci 2019; 20:E1837. [PMID: 31013934 PMCID: PMC6515405 DOI: 10.3390/ijms20081837] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/21/2022] Open
Abstract
The endocannabinoid system has emerged as a promising target for the treatment of numerous diseases, including cancer, neurodegenerative disorders, and metabolic syndromes. Thus far, two cannabinoid receptors, CB1 and CB2, have been discovered, which are found predominantly in the central nervous system (CB1) or the immune system (CB2), among other organs and tissues. CB1 receptor ligands have been shown to induce a complex pattern of intracellular effects. The binding of a ligand induces distinct conformational changes in the receptor, which will eventually translate into distinct intracellular signaling pathways through coupling to specific intracellular effector proteins. These proteins can mediate receptor desensitization, trafficking, or signaling. Ligand specificity and selectivity, complex cellular components, and the concomitant expression of other proteins (which either regulate the CB1 receptor or are regulated by the CB1 receptor) will affect the therapeutic outcome of its targeting. With an increased interest in G protein-coupled receptors (GPCR) research, in-depth studies using mutations, biological assays, and spectroscopic techniques (such as NMR, EPR, MS, FRET, and X-ray crystallography), as well as computational modelling, have begun to reveal a set of concerted structural features in Class A GPCRs which relate to signaling pathways and the mechanisms of ligand-induced activation, deactivation, or activity modulation. This review will focus on the structural features of the CB1 receptor, mutations known to bias its signaling, and reported studies of CB1 receptor ligands to control its specific signaling.
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Affiliation(s)
- Rufaida Al-Zoubi
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science & Technology, P.O.BOX 3030, Irbid 22110, Jordan.
| | - Paula Morales
- Departamento de Química-Física Biológica, Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain.
| | - Patricia H Reggio
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, NC 27412, USA.
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8
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Nealon CM, Henderson-Redmond AN, Hale DE, Morgan DJ. Tolerance to WIN55,212-2 is delayed in desensitization-resistant S426A/S430A mice. Neuropharmacology 2019; 148:151-159. [PMID: 30629988 PMCID: PMC6535342 DOI: 10.1016/j.neuropharm.2018.12.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 12/05/2018] [Accepted: 12/21/2018] [Indexed: 02/08/2023]
Abstract
Tolerance to cannabinoid agonists can develop through desensitization of the cannabinoid receptor 1 (CB1) following prolonged administration. Desensitization results from phosphorylation of CB1 by a G protein-coupled receptor kinase (GRK), and subsequent association of the receptor with arrestin. Mice expressing a mutant form of CB1, in which the serine residues at two putative phosphorylation sites necessary for desensitization have been replaced by non-phosphorylatable alanines (S426A/S430A), display reduced tolerance to Δ9-tetrahydrocannabinol (Δ9-THC). Tolerance to the antinociceptive effects of WIN55,212-2 was delayed in S426A/S430A mutants using the tail-flick and formalin tests. However, tolerance to the antinociceptive effects of once daily CP55,940 injections was not significantly delayed in S426A/S430A mutant mice using either of these tests. Interestingly, the dose response curve shifts for the hypothermic and antinociceptive effects of CP55,940 that were induced by chronic treatment with this agonist in wild-type mice were blocked in S426A/S430A mutant mice. Assessment of mechanical allodynia in mice exhibiting chronic cisplatin-evoked neuropathic pain found that tolerance to the anti-allodynic effects WIN55,212-2 but not CP55,940 was delayed in S426A/S430A mice compared to wild-type littermates. Despite these deficits in tolerance, S426A/S430A mutant mice eventually developed tolerance to both WIN55,212-2 and CP55,940 for all pain assays that were examined, suggesting that other mechanisms likely contribute to tolerance for these cannabinoid agonists. These findings suggest that GRK- and βarrestin2-mediated desensitization of CB1 may strongly contribute to the rate of tolerance to the antinociceptive effects of WIN55,212-2, and raises the possibility of agonist-specific mechanisms of cannabinoid tolerance.
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Affiliation(s)
- Caitlin M Nealon
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Angela N Henderson-Redmond
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - David E Hale
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Daniel J Morgan
- Department of Anesthesiology and Perioperative Medicine, Penn State University College of Medicine, Hershey, PA, 17033, USA; Department of Pharmacology, Penn State University College of Medicine, Hershey, PA, 17033, USA; Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA.
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9
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Wilson CD, Tai S, Ewing L, Crane J, Lockhart T, Fujiwara R, Radominska-Pandya A, Fantegrossi WE. Convulsant Effects of Abused Synthetic Cannabinoids JWH-018 and 5F-AB-PINACA Are Mediated by Agonist Actions at CB1 Receptors in Mice. J Pharmacol Exp Ther 2019; 368:146-156. [PMID: 30420360 PMCID: PMC6323622 DOI: 10.1124/jpet.118.251157] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 11/07/2018] [Indexed: 01/29/2023] Open
Abstract
Convulsant effects of abused synthetic cannabinoid (SCB) drugs have been reported in humans and laboratory animals, but the mechanism of these effects is not known. We compared convulsant effects of partial CB1R agonist ∆9-tetrahydrocannabinol (THC), full CB1R agonist SCBs JWH-018 and 5F-AB-PINACA, and classic chemical convulsant pentylenetetrazol (PTZ) using an observational rating scale in mice. THC did not elicit convulsions, but both SCBs did so as effectively as and more potently than PTZ. SCB-elicited convulsions were attenuated by the CB1R antagonist rimonabant or by THC, or by dose regimens of THC and JWH-018, which downregulate and desensitize CB1Rs. None of these treatments altered the convulsant effects of PTZ, although diazepam attenuated PTZ-elicited convulsions without altering SCB-induced convulsant effects. Repeated administration of a subthreshold dose of PTZ kindled convulsant effects, but this was not observed with the SCBs, and no cross-kindling was observed. Repeated administration of the SCBs resulted in tolerance to convulsant effects, but no cross-tolerance to PTZ was observed. Inhibition on Phase I metabolism via nonselective inhibition of CYP450s with 1-aminobenzotriazole potentiated the hypothermic effects of the SCBs and protected against the convulsant effects of JWH-018, but not those of 5F-AB-PINACA or PTZ. Incubation of human liver microsomes with the SCBs showed that JWH-018 is eliminated via oxidation, whereas 5F-AB-PINACA is not. These studies suggest that SCB-elicited convulsions are mediated by high intrinsic efficacy at CB1Rs and that benzodiazepines may not be effective treatments. Finally, drug metabolism may dramatically modulate the convulsant effects of some, but not all, SCBs.
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Affiliation(s)
- Catheryn D Wilson
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Sherrica Tai
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Laura Ewing
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Jasmine Crane
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Taylor Lockhart
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ryochi Fujiwara
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Anna Radominska-Pandya
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - William E Fantegrossi
- Departments of Pharmacology and Toxicology (C.D.W., S.T., L.E., J.C., T.L., W.E.F.) and Biochemistry and Molecular Biology (R.F., A.R.-P.), College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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10
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Kendall DA, Yudowski GA. Cannabinoid Receptors in the Central Nervous System: Their Signaling and Roles in Disease. Front Cell Neurosci 2017; 10:294. [PMID: 28101004 PMCID: PMC5209363 DOI: 10.3389/fncel.2016.00294] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 12/08/2016] [Indexed: 11/15/2022] Open
Abstract
The identification and cloning of the two major cannabinoid (CB1 and CB2) receptors together with the discovery of their endogenous ligands in the late 80s and early 90s, resulted in a major effort aimed at understanding the mechanisms and physiological roles of the endocannabinoid system (ECS). Due to its expression and localization in the central nervous system (CNS), the CB1 receptor together with its endogenous ligands (endocannabinoids (eCB)) and the enzymes involved in their synthesis and degradation, has been implicated in multiple pathophysiological events ranging from memory deficits to neurodegenerative disorders among others. In this review, we will provide a general overview of the ECS with emphasis on the CB1 receptor in health and disease. We will describe our current understanding of the complex aspects of receptor signaling and trafficking, including the non-canonical signaling pathways such as those mediated by β-arrestins within the context of functional selectivity and ligand bias. Finally, we will highlight some of the disorders in which CB1 receptors have been implicated. Significant knowledge has been achieved over the last 30 years. However, much more research is still needed to fully understand the complex roles of the ECS, particularly in vivo and to unlock its true potential as a source of therapeutic targets.
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Affiliation(s)
- Debra A Kendall
- Department of Pharmaceutical Sciences, University of Connecticut Storrs, CT, USA
| | - Guillermo A Yudowski
- Department of Anatomy and Neurobiology, University of Puerto Rico, Medical Sciences CampusSan Juan, Puerto Rico; Institute of Neurobiology, University of Puerto RicoSan Juan, Puerto Rico
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11
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Nogueras-Ortiz C, Yudowski GA. The Multiple Waves of Cannabinoid 1 Receptor Signaling. Mol Pharmacol 2016; 90:620-626. [PMID: 27338082 PMCID: PMC11037448 DOI: 10.1124/mol.116.104539] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/22/2016] [Indexed: 12/15/2022] Open
Abstract
The cannabinoid 1 receptor (CB1R) is one of the most abundant G protein-coupled receptors (GPCRs) in the central nervous system, with key roles during neurotransmitter release and synaptic plasticity. Upon ligand activation, CB1Rs may signal in three different spatiotemporal waves. The first wave, which is transient (<10 minutes) and initiated by heterotrimeric G proteins, is followed by a second wave (>5 minutes) that is mediated by β-arrestins. The third and final wave occurs at intracellular compartments and could be elicited by G proteins or β-arrestins. This complexity presents multiple challenges, including the correct classification of receptor ligands, the identification of the signaling pathways regulated by each wave, and the underlying molecular mechanisms and physiologic impacts of these waves. Simultaneously, it provides new opportunities to harness the therapeutic potential of the cannabinoid system and other GPCRs. Over the last several years, we have significantly expanded our understanding of the mechanisms and pathways downstream from the CB1R. The identification of receptor mutations that can bias signaling to specific pathways and the use of siRNA technology have been key tools to identifying which signaling cascades are controlled by G proteins or β-arrestins. Here, we review our current knowledge on CB1R signaling, with particular emphasis on the mechanisms and cascades mediated by β-arrestins downstream from the CB1R.
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Affiliation(s)
- Carlos Nogueras-Ortiz
- Institute of Neurobiology(C.N.-O., G.A.Y.) and Department of Anatomy and Neurobiology (G.A.Y.), University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Guillermo A Yudowski
- Institute of Neurobiology(C.N.-O., G.A.Y.) and Department of Anatomy and Neurobiology (G.A.Y.), University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
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