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Simone JJ, Green MR, McCormick CM. Endocannabinoid system contributions to sex-specific adolescent neurodevelopment. Prog Neuropsychopharmacol Biol Psychiatry 2022; 113:110438. [PMID: 34534603 DOI: 10.1016/j.pnpbp.2021.110438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 08/13/2021] [Accepted: 09/08/2021] [Indexed: 01/08/2023]
Abstract
With an increasing number of countries and states adopting legislation permitting the use of cannabis for medical purposes, there is a growing interest among health and research professionals into the system through which cannabinoids principally act, the endocannabinoid system (ECS). Much of the seminal research into the ECS dates back only 30 years and, although there has been tremendous development within the field during this time, many questions remain. More recently, investigations have emerged examining the contributions of the ECS to normative development and the effect of altering this system during important critical periods. One such period is adolescence, a unique period during which brain and behaviours are maturing and reorganizing in preparation for adulthood, including shifts in endocannabinoid biology. The purpose of this review is to discuss findings to date regarding the maturation of the ECS during adolescence and the consequences of manipulations of the ECS during this period to normative neurodevelopmental processes, as well as highlight sex differences in ECS function, important technical considerations, and future directions. Because most of what we know is derived from preclinical studies on rodents, we provide relevant background of this model and some commentary on the translational relevance of the research in this area.
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Affiliation(s)
- Jonathan J Simone
- Department of Biological Sciences, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, ON L2S 3A1, Canada; Centre for Neuroscience, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, ON L2S 3A1, Canada; Huxley Health Inc., 8820 Jane St., Concord, ON, L4K 2M9, Canada; eCB Consulting Inc., PO Box 652, 3 Cameron St. W., Cannington, ON L0E 1E0, Canada; Medical Cannabis Canada, 601-3500 Lakeshore Rd. W., Oakville, ON L6L 0B4, Canada.
| | - Matthew R Green
- eCB Consulting Inc., PO Box 652, 3 Cameron St. W., Cannington, ON L0E 1E0, Canada; Medical Cannabis Canada, 601-3500 Lakeshore Rd. W., Oakville, ON L6L 0B4, Canada.
| | - Cheryl M McCormick
- Department of Biological Sciences, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, ON L2S 3A1, Canada; Centre for Neuroscience, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, ON L2S 3A1, Canada; Department of Psychology, 1812 Sir Isaac Brock Way, Brock University, St. Catharines, ON L2S 3A1, Canada.
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Boczek T, Zylinska L. Receptor-Dependent and Independent Regulation of Voltage-Gated Ca 2+ Channels and Ca 2+-Permeable Channels by Endocannabinoids in the Brain. Int J Mol Sci 2021; 22:ijms22158168. [PMID: 34360934 PMCID: PMC8348342 DOI: 10.3390/ijms22158168] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/27/2022] Open
Abstract
The activity of specific populations of neurons in different brain areas makes decisions regarding proper synaptic transmission, the ability to make adaptations in response to different external signals, as well as the triggering of specific regulatory pathways to sustain neural function. The endocannabinoid system (ECS) appears to be a very important, highly expressed, and active system of control in the central nervous system (CNS). Functionally, it allows the cells to respond quickly to processes that occur during synaptic transmission, but can also induce long-term changes. The endocannabinoids (eCBs) belong to a large family of bioactive lipid mediators that includes amides, esters, and ethers of long-chain polyunsaturated fatty acids. They are produced “on demand” from the precursors located in the membranes, exhibit a short half-life, and play a key role as retrograde messengers. eCBs act mainly through two receptors, CB1R and CB2R, which belong to the G-protein coupled receptor superfamily (GPCRs), but can also exert their action via multiple non-receptor pathways. The action of eCBs depends on Ca2+, but eCBs can also regulate downstream Ca2+ signaling. In this short review, we focus on the regulation of neuronal calcium channels by the most effective members of eCBs-2-arachidonoylglycerol (2-AG), anandamide (AEA) and originating from AEA-N-arachidonoylglycine (NAGly), to better understand the contribution of ECS to brain function under physiological conditions.
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Patricio-Martínez A, Sánchez-Zavaleta R, Angulo-Cruz I, Gutierrez-Praxedis L, Ramírez E, Martínez-García I, Limón ID. The Acute Activation of the CB1 Receptor in the Hippocampus Decreases Neurotoxicity and Prevents Spatial Memory Impairment in Rats Lesioned with β-Amyloid 25-35. Neuroscience 2019; 416:239-254. [PMID: 31400487 DOI: 10.1016/j.neuroscience.2019.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/23/2022]
Abstract
Given their anti-inflammatory properties, cannabinoids have been shown to be neuroprotective agents and to reduce excitotoxicity, through the activation of the Cannabinoid receptor type 1 (CB1r). These properties have led to CB1r being proposed as pharmacological targets for the treatment of various neurodegenerative diseases. Amyloid-β 25-35 (Aβ25-35) induces the expression of inducible nitric oxide synthase (iNOS) and increases nitric oxide (NO●) levels. It has been observed that increased NO● concentrations trigger biochemical pathways that contribute to neuronal death and cognitive damage. This study aimed to evaluate the neuroprotective effect of an acute activation of CB1r on spatial memory and its impact on iNOS protein expression, NO● levels, gliosis and the neurodegenerative process induced by the injection of Aβ(25-35) into the CA1 subfield of the hippocampus. ACEA [1 μM/1 μL] and Aβ(25-35) [100 μM/1 μL] and their respective vehicle groups were injected into the CA1 subfield of the hippocampus. The animals were tested for spatial learning and memory in the eight-arm radial maze, with the results revealing that the administration of ACEA plus Aβ(25-35) improves learning and memory processes, in contrast with the Aβ(25-35) group. Moreover, ACEA plus Aβ(25-35) prevented both the increase in iNOS protein and NO● levels and the reactive gliosis induced by Aβ(25-35). Importantly, neurodegeneration was significantly reduced by the administration of ACEA plus Aβ(25-35) in the CA1 subfield of the hippocampus. The data obtained in the present research suggest that the acute early activation of CB1r is crucial for neuroprotection.
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Affiliation(s)
- Aleidy Patricio-Martínez
- Laboratorio de Neurofarmacología, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico; Facultad de Ciencias Biológicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Rodolfo Sánchez-Zavaleta
- Laboratorio de Neurofarmacología, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Isael Angulo-Cruz
- Laboratorio de Neurofarmacología, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Liliana Gutierrez-Praxedis
- Laboratorio de Neurofarmacología, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Eleazar Ramírez
- Laboratorio de Neurofarmacología, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Isabel Martínez-García
- Laboratorio de Neuroquímica, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Ilhuicamina Daniel Limón
- Laboratorio de Neurofarmacología, Facultad de Ciencias Químicas-Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
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Costain WJ, Rasquinha I, Comas T, Hewitt M, Aylsworth A, Rouleau Y, Marleau V, Soo EC, Tauskela JS. Analysis of the pharmacological properties of JWH-122 isomers and THJ-2201, RCS-4 and AB-CHMINACA in HEK293T cells and hippocampal neurons. Eur J Pharmacol 2018; 823:96-104. [PMID: 29408093 DOI: 10.1016/j.ejphar.2018.01.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 01/04/2018] [Accepted: 01/25/2018] [Indexed: 11/15/2022]
Abstract
Synthetic cannabinoids are marketed as legal alternatives to Δ9-THC, and are a growing worldwide concern as these drugs are associated with severe adverse effects. Unfortunately, insufficient information regarding the physiological and pharmacological effects of emerging synthetic cannabinoids (ESCs) makes their regulation by government authorities difficult. One strategy used to evade regulation is to distribute isomers of regulated synthetic cannabinoids. This study characterized the pharmacological properties of a panel of ESCs in comparison to Δ9-THC, as well as six JWH-122 isomers relative to its parent compound (JWH-122-4). Two cell-based assays were used to determine the potency and efficacy of ESCs and a panel of reference cannabinoids. HEK293T cells were transfected with human cannabinoid receptor 1 (CB1) and pGloSensor-22F, and the inhibition of forskolin-stimulated cyclic adenosine monophosphate (cAMP) levels was monitored in live cells. All ESCs examined were classified as agonists, with the following rank order of potency: Win 55,212-2 > CP 55,940 > JWH-122-4 > Δ9-THC ≈ RCS-4 ≈ THJ-2201 > JWH-122-5 > JWH-122-7 > JWH-122-2 ≈ AB-CHMINACA > JWH-122-8 > JWH-122-6 > JWH-122-3. Evaluation of ESC-stimulated Ca2+ transients in cultured rat primary hippocampal neurons confirmed the efficacy of four of the most potent ESCs (JWH-122-4, JWH-122-5, JWH-122-7 and AB-CHMINACA). This work helps regulatory agencies make informed decisions concerning these poorly characterized recreational drugs.
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Affiliation(s)
- Willard J Costain
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6.
| | - Ingrid Rasquinha
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6
| | - Tanya Comas
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6
| | - Melissa Hewitt
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6
| | - Amy Aylsworth
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6
| | - Yanouchka Rouleau
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6
| | - Vincent Marleau
- Analytical and Forensic Services Division, Contraband Drug Analysis, Canada Border Services Agency, 79 Bentley Avenue, 2nd Floor, Ottawa, Ontario, Canada K1A 0L8
| | - Evelyn C Soo
- Health Products and Food Branch, Biologics and Genetic Therapies Directorate, Health Canada, 150 Tunney's Pasture Driveway #1605-676, Ottawa, Ontario, Canada K1A 0K9
| | - Joseph S Tauskela
- Department of Translational Bioscience, Human Health Therapeutics, National Research Council, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6
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Cannabinoid CB1 and CB2 receptors differentially modulate L- and T-type Ca 2+ channels in rat retinal ganglion cells. Neuropharmacology 2017; 124:143-156. [PMID: 28431968 DOI: 10.1016/j.neuropharm.2017.04.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/15/2017] [Accepted: 04/17/2017] [Indexed: 01/09/2023]
Abstract
Endocannabinoid signaling system is involved in regulating multiple neuronal functions in the central nervous system by activating G-protein coupled cannabinoid CB1 and CB2 receptors (CB1Rs and CB2Rs). Growing evidence has shown that CB1Rs and CB2Rs are extensively expressed in retinal ganglion cells (RGCs). Here, modulation of L- and T-types Ca2+ channels by activating CB1Rs and CB2Rs in RGCs was investigated. Triple immunofluorescent staining showed that L-type subunit CaV1.2 was co-localized with T-type subunits (CaV3.1, CaV3.2 and CaV3.3) in rat RGCs. In acutely isolated rat RGCs, the CB1R agonist WIN55212-2 suppressed both peak and steady-state Ca2+ currents in a dose-dependent manner, with IC50 being 9.6 μM and 8.4 μM, respectively. It was further shown that activation of CB1Rs by WIN55212-2 or ACEA, another CB1R agonist, significantly suppressed both L- and T-type Ca2+ currents, and shifted inactivation curve of T-type one toward hyperpolarization direction. While the effect on L-type Ca2+ channels was mediated by intracellular cAMP/protein kinase A (PKA), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and calcium/calmodulin-dependent protein kinase II (CaMKII) signaling pathways, only CaMKII signaling pathway was involved in the effect on T-type Ca2+ channels. Furthermore, CB65 and HU308, two specific CB2R agonists, significantly suppressed T-type Ca2+ channels, which was mediated by intracellular cAMP/PKA and CaMKII signaling pathways, but had no effect on L-type channels. These results imply that endogenous cannabinoids may modulate the excitability and the output of RGCs by differentially suppressing the activity of L- and T-type Ca2+ channels through activation of CB1Rs and CB2Rs. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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Abstract
Cannabis sativa has long been used for medicinal purposes. To improve safety and efficacy, compounds from C. sativa were purified or synthesized and named under an umbrella group as cannabinoids. Currently, several cannabinoids may be prescribed in Canada for a variety of indications such as nausea and pain. More recently, an increasing number of reports suggest other salutary effects associated with endogenous cannabinoid signaling including cardioprotection. The therapeutic potential of cannabinoids is therefore extended; however, evidence is limited and mechanisms remain unclear. In addition, the use of cannabinoids clinically has been hindered due to pronounced psychoactive side effects. This review provides an overview on the endocannabinoid system, including known physiological roles, and conditions in which cannabinoid receptor signaling has been implicated.
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Affiliation(s)
- Yan Lu
- a College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, 750 McDermot Avenue, Winnipeg, MB R3E 0T5, Canada.,b Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, MB R2H 2A6, Canada
| | - Hope D Anderson
- a College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, 750 McDermot Avenue, Winnipeg, MB R3E 0T5, Canada.,b Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, MB R2H 2A6, Canada.,c Department of Pharmacology and Therapeutics, Max Rady College of Medicine, University of Manitoba, 753 McDermot Avenue, Winnipeg, MB R3E 0T6, Canada
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Ligresti A, De Petrocellis L, Di Marzo V. From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology. Physiol Rev 2016; 96:1593-659. [DOI: 10.1152/physrev.00002.2016] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Apart from having been used and misused for at least four millennia for, among others, recreational and medicinal purposes, the cannabis plant and its most peculiar chemical components, the plant cannabinoids (phytocannabinoids), have the merit to have led humanity to discover one of the most intriguing and pleiotropic endogenous signaling systems, the endocannabinoid system (ECS). This review article aims to describe and critically discuss, in the most comprehensive possible manner, the multifaceted aspects of 1) the pharmacology and potential impact on mammalian physiology of all major phytocannabinoids, and not only of the most famous one Δ9-tetrahydrocannabinol, and 2) the adaptive pro-homeostatic physiological, or maladaptive pathological, roles of the ECS in mammalian cells, tissues, and organs. In doing so, we have respected the chronological order of the milestones of the millennial route from medicinal/recreational cannabis to the ECS and beyond, as it is now clear that some of the early steps in this long path, which were originally neglected, are becoming important again. The emerging picture is rather complex, but still supports the belief that more important discoveries on human physiology, and new therapies, might come in the future from new knowledge in this field.
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Affiliation(s)
- Alessia Ligresti
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli, Italy
| | - Luciano De Petrocellis
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli, Italy
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli, Italy
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Effect of synthetic cannabinoids on spontaneous neuronal activity: Evaluation using Ca 2+ spiking and multi-electrode arrays. Eur J Pharmacol 2016; 786:148-160. [DOI: 10.1016/j.ejphar.2016.05.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/18/2016] [Accepted: 05/30/2016] [Indexed: 01/22/2023]
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Costain WJ, Tauskela JS, Rasquinha I, Comas T, Hewitt M, Marleau V, Soo EC. Pharmacological characterization of emerging synthetic cannabinoids in HEK293T cells and hippocampal neurons. Eur J Pharmacol 2016; 786:234-245. [DOI: 10.1016/j.ejphar.2016.05.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 10/21/2022]
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Gambi F, De Berardis D, Sepede G, Quartesan R, Calcagni E, Salerno RM, Conti CM, Ferro FM. Cannabinoid Receptors and Their Relationships with Neuropsychiatric Disorders. Int J Immunopathol Pharmacol 2016; 18:15-9. [PMID: 15698507 DOI: 10.1177/039463200501800103] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cannabinoids are the costituents of the marijuana plants. The central effects of exogenous cannabinoids are implicated in enhancing mood, altering emotional states, and interfering in the formation of short-term memory. Cannabinoid receptors are G protein-coupled receptors with seven transmembrane domains that are expressed on the cell surface with their binding domain exposed to the extracellular space. To date, two cannabinoid receptors have been cloned, CB1 and CB2. Recent evidence suggests that a third ‘CB3’ receptor may be cloned in the near future. The endocannabinoids may represent the first members of a new classes of neuromodulators, that are not stored in cell vesicles, but rather synthesised by the cell on demand. The endogenous cannabinoid system could play a central role in several neuropsychiatric disorders and is also involved in other conditions such as pain, spasticity and neuroprotection. Implication of cannabinoid system in the pathogenesis and development of schizophrenia is also discussed.
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Affiliation(s)
- F Gambi
- Psychiatry Division, University of Chieti, Italy.
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Ghosh B, Green MV, Krogh KA, Thayer SA. Interleukin-1β activates an Src family kinase to stimulate the plasma membrane Ca2+ pump in hippocampal neurons. J Neurophysiol 2016; 115:1875-85. [PMID: 26843596 PMCID: PMC4869483 DOI: 10.1152/jn.00541.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 01/23/2016] [Indexed: 01/09/2023] Open
Abstract
The plasma membrane Ca(2+) ATPase (PMCA) plays a major role in clearing Ca(2+) from the neuronal cytoplasm. The cytoplasmic Ca(2+) clearance rate affects neuronal excitability, synaptic plasticity, and neurotransmission. Here, we examined the modulation of PMCA activity by PTKs in hippocampal neurons. PMCA-mediated Ca(2+) clearance slowed in the presence of pyrazolopyrimidine 2, an inhibitor of Src family kinases (SFKs), and accelerated in the presence of C2-ceramide, an activator of PTKs. Ca(2+) clearance kinetics were attenuated in cells expressing a dominant-negative Src mutant, suggesting that the pump is tonically stimulated by a PTK. Tonic stimulation was reduced in hippocampal neurons expressing short hairpin (sh)RNA directed to mRNA for Yes. shRNA-mediated knockdown of PMCA isoform 1 (PMCA1) removed tonic stimulation of Ca(2+) clearance, indicating that the kinase stimulates PMCA1. IL-1β accelerated Ca(2+) clearance in a manner blocked by an IL-1β receptor antagonist or by an inhibitor of neutral sphingomyelinase, the enzyme that produces ceramide. Thus IL-1β activates an SFK to stimulate the plasma membrane Ca(2+) pump, decreasing the duration of Ca(2+) transients in hippocampal neurons.
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Affiliation(s)
- Biswarup Ghosh
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Matthew V Green
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Kelly A Krogh
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Stanley A Thayer
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
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Cannabinoid receptor 1 ligands revisited: Pharmacological assessment in the ACTOne system. Anal Biochem 2016; 498:8-28. [PMID: 26772161 DOI: 10.1016/j.ab.2015.12.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/22/2015] [Accepted: 12/29/2015] [Indexed: 11/23/2022]
Abstract
In vitro cannabinoid pharmacology has evolved over time from simple receptor binding to include [(35)S]GTPγ, β-arrestin, and cAMP assays. Each assay has benefits and drawbacks; however, no single functional system has been used for high-throughput evaluation of compounds from binding to pharmacological functionality and antagonist assessment in a well-characterized human cell line. In this study, we evaluated and validated one system-ACTOne human embryonic kidney cells transfected with a cyclic nucleotide gated channel and cannabinoid receptor 1 (CB1)-and compared human CB1 affinity, functional, and antagonistic effects on cAMP with previously published results. The study was conducted on a diverse group of CB1 ligands, including endocannabinoids and related compounds, 2-AG, AEA, MAEA, and ACEA, the phytocannabinoid Δ(9) THC, and synthetic cannabinoids CP 55,940, WIN 55,212-2, SR 141716A, CP 945,598, and WIN 55,212-3. Our results were compared with literature values where human CB1 was used for affinity determination and cAMP was used as a functional readout. Here we report the first detailed evaluation of the ACTOne assay for the pharmacological evaluation of CB1 ligands. The results from the study reveal some interesting deviations from previously reported functional activities of the aforementioned ligands.
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Yang W, Li Q, Wang SY, Gao F, Qian WJ, Li F, Ji M, Sun XH, Miao Y, Wang Z. Cannabinoid receptor agonists modulate calcium channels in rat retinal müller cells. Neuroscience 2016; 313:213-24. [DOI: 10.1016/j.neuroscience.2015.11.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 11/10/2015] [Accepted: 11/17/2015] [Indexed: 10/22/2022]
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Murataeva N, Li S, Oehler O, Miller S, Dhopeshwarkar A, Hu SSJ, Bonanno JA, Bradshaw H, Mackie K, McHugh D, Straiker A. Cannabinoid-induced chemotaxis in bovine corneal epithelial cells. Invest Ophthalmol Vis Sci 2015; 56:3304-13. [PMID: 26024113 DOI: 10.1167/iovs.14-15675] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Cannabinoid CB1 receptors are found in abundance in the vertebrate eye, with most tissue types expressing this receptor. However, the function of CB1 receptors in corneal epithelial cells (CECs) is poorly understood. Interestingly, the corneas of CB1 knockout mice heal more slowly after injury via a mechanism proposed to involve protein kinase B (Akt) activation, chemokinesis, and cell proliferation. The current study examined the role of cannabinoids in CEC migration in greater detail. METHODS We determined the role of CB1 receptors in corneal healing. We examined the consequences of their activation on migration and proliferation in bovine CECs (bCECs). We additionally examined the mRNA profile of cannabinoid-related genes and CB1 protein expression as well as CB1 signaling in bovine CECs. RESULTS We now report that activation of CB1 with physiologically relevant concentrations of the synthetic agonist WIN55212-2 (WIN) induces bCEC migration via chemotaxis, an effect fully blocked by the CB1 receptor antagonist SR141716. The endogenous agonist 2-arachidonoylglycerol (2-AG) also enhances migration. Separately, mRNA for most cannabinoid-related proteins are present in bovine corneal epithelium and cultured bCECs. Notably absent are CB2 receptors and the 2-AG synthesizing enzyme diglycerol lipase-α (DAGLα). The signaling profile of CB1 activation is complex, with inactivation of mitogen-activated protein kinase (MAPK). Lastly, CB1 activation does not induce bCEC proliferation, but may instead antagonize EGF-induced proliferation. CONCLUSIONS In summary, we find that CB1-based signaling machinery is present in bovine cornea and that activation of this system induces chemotaxis.
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Affiliation(s)
- Natalia Murataeva
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
| | - Shimin Li
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Olivia Oehler
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
| | - Sally Miller
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
| | - Amey Dhopeshwarkar
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
| | - Sherry Shu-Jung Hu
- Department of Psychology, National Cheng Kung University, Tainan, Taiwan
| | - Joseph A Bonanno
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Heather Bradshaw
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
| | - Ken Mackie
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
| | - Douglas McHugh
- Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, Connecticut, United States
| | - Alex Straiker
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences Indiana University, Bloomington, Indiana, United States
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Kokona D, Thermos K. Synthetic and endogenous cannabinoids protect retinal neurons from AMPA excitotoxicity in vivo, via activation of CB1 receptors: Involvement of PI3K/Akt and MEK/ERK signaling pathways. Exp Eye Res 2015; 136:45-58. [DOI: 10.1016/j.exer.2015.05.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 05/14/2015] [Accepted: 05/15/2015] [Indexed: 11/29/2022]
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Moris D, Georgopoulos S, Felekouras E, Patsouris E, Theocharis S. The effect of endocannabinoid system in ischemia-reperfusion injury: a friend or a foe? Expert Opin Ther Targets 2015; 19:1261-75. [PMID: 25936364 DOI: 10.1517/14728222.2015.1043268] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION In recent years, the endocannabinoid system has emerged as a new therapeutic target in variety of disorders associated with inflammation and tissue injury, including those of the neuronal, liver, renal and cardiovascular system. The aim of the present review is to elucidate the effect of endocannabinoid system on ischemia reperfusion injury (IRI) in different organs and systems. AREAS COVERED The MEDLINE/PubMed database was searched for publications with the medical subject heading Cannabinoids* (CBs), CB receptors*, organ*, ischemia/reperfusion injury*, endocannabinoid* and system*. The initial relevant studies retrieved from the literature were 91 from PubMed. This number was initially limited to 35, after excluding the reviews and studies reporting data for receptors other than cannabinoid. EXPERT OPINION CB2 receptors may play an important compensatory role in controlling tissue inflammation and injury in cells of the neuronal, cardiovascular, liver and renal systems, as well as in infiltrating monocytes/macrophages and leukocytes during various pathological conditions of the systems (atherosclerosis, restenosis, stroke, myocardial infarction, heart, liver and renal failure). These receptors limit inflammation and associated tissue injury. On the basis of preclinical results, pharmacological modulation of CB2 receptors may hold a unique therapeutic potential in stroke, myocardial infarction, atherosclerosis, IRI and liver disease.
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Affiliation(s)
- Demetrios Moris
- National and Kapodistrian University of Athens , Anastasiou Gennadiou 56, 11474, Athens , Greece +30 210 6440590 ;
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Johnson BN, Palmer CP, Bourgeois EB, Elkind JA, Putnam BJ, Cohen AS. Augmented Inhibition from Cannabinoid-Sensitive Interneurons Diminishes CA1 Output after Traumatic Brain Injury. Front Cell Neurosci 2014; 8:435. [PMID: 25565968 PMCID: PMC4271495 DOI: 10.3389/fncel.2014.00435] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 12/02/2014] [Indexed: 11/15/2022] Open
Abstract
The neurological impairments associated with traumatic brain injury include learning and memory deficits and increased risk of seizures. The hippocampus is critically involved in both of these phenomena and highly susceptible to damage by traumatic brain injury. To examine network activity in the hippocampal CA1 region after lateral fluid percussion injury, we used a combination of voltage-sensitive dye, field potential, and patch clamp recording in mouse hippocampal brain slices. When the stratum radiatum (SR) was stimulated in slices from injured mice, we found decreased depolarization in SR and increased hyperpolarization in stratum oriens (SO), together with a decrease in the percentage of pyramidal neurons firing stimulus-evoked action potentials. Increased hyperpolarization in SO persisted when glutamatergic transmission was blocked. However, we found no changes in SO responses when the alveus was stimulated to directly activate SO. These results suggest that the increased SO hyperpolarization evoked by SR stimulation was mediated by interneurons that have cell bodies and/or axons in SR, and form synapses in stratum pyramidale and SO. A low concentration (100 nM) of the synthetic cannabinoid WIN55,212-2, restored CA1 output in slices from injured animals. These findings support the hypothesis that increased GABAergic signaling by cannabinoid-sensitive interneurons contributes to the reduced CA1 output following traumatic brain injury.
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Affiliation(s)
- Brian N Johnson
- Children's Hospital of Philadelphia Research Institute, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Chris P Palmer
- Department of Neuroscience, University of Pennsylvania School of Medicine , Philadelphia, PA , USA
| | - Elliot B Bourgeois
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School , Boston, MA , USA
| | - Jaclynn A Elkind
- Children's Hospital of Philadelphia Research Institute, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Brendan J Putnam
- Children's Hospital of Philadelphia Research Institute, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Akiva S Cohen
- Children's Hospital of Philadelphia Research Institute, Children's Hospital of Philadelphia , Philadelphia, PA , USA ; Department of Pediatrics, University of Pennsylvania School of Medicine , Philadelphia, PA , USA
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Abstract
The ECs (endocannabinoids) AEA (anandamide) and 2-AG (2-arachidonoylglycerol) and their lipid congeners OEA (N-oleoylethanolamide) and PEA (N-palmitoylethanolamide) are multifunctional lipophilic signalling molecules. The ECs, OEA and PEA have multiple physiological roles including involvement in learning and memory, neuroinflammation, oxidative stress, neuroprotection and neurogenesis. They have also been implicated in the pathology of, or perhaps protective responses to, neurodegenerative diseases. This is particularly the case with Alzheimer's disease, the most common age-related dementia associated with impairments in learning and memory accompanied by neuroinflammation, oxidative stress and neurodegeneration. The present mini-review examines the evidence supporting the roles that ECs appear to play in Alzheimer's disease and the potential for beneficial therapeutic manipulation of the EC signalling system.
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Permanent suppression of cortical oscillations in mice after adolescent exposure to cannabinoids: receptor mechanisms. Neuropharmacology 2014; 86:161-73. [PMID: 25036610 DOI: 10.1016/j.neuropharm.2014.07.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/12/2014] [Accepted: 07/02/2014] [Indexed: 12/19/2022]
Abstract
Marijuana use in adolescence, but not adulthood, may permanently impair cognitive functioning and increase the risk of developing schizophrenia. Cortical oscillations are patterns of neural network activity implicated in cognitive processing, and are abnormal in patients with schizophrenia. We have recently reported that cortical oscillations are suppressed in adult mice that were treated with the cannabinoids WIN55,212-2 (WIN) or Δ(9)tetrahydrocannabinol (THC) in adolescence, but not adulthood. WIN and THC are cannabinoid-1 (CB1R) and CB2R agonists, and also have activity at non-cannabinoid receptor targets. However, as acute WIN and THC administration can suppress oscillations through CB1Rs, we hypothesize that a similar mechanism underlies the permanent suppression of oscillations by repeated cannabinoid exposure in adolescence. Here we test the prediction that cannabinoid exposure in adolescence permanently suppresses cortical oscillations by acting through CB1Rs, and that these suppressive effects can be antagonized by a CB1R antagonist. We treated adolescent mice with various cannabinoid compounds, and pharmacologically-evoked oscillations in local field potentials (LFPs) in vitro in adults. We find that WIN exposure for six days in early adolescence suppresses oscillations preferentially in adult medial prefrontal cortex (mPFC) via CB1Rs, and that a similar CB1R mechanism accounts for the suppressive effects of long-term (20 day) adolescent THC in adult somatosensory cortex (SCx). Unexpectedly, we also find that CB2Rs may be involved in the suppression of oscillations in both mPFC and SCx by long-term adolescent cannabinoid exposure, and that non-cannabinoid receptors may also contribute to oscillation suppression in adult mPFC. These findings represent a novel attempt to antagonize the effects of adolescent cannabinoid exposure on neural network activity, and reveal the contribution of non-CB1R targets to the suppression of cortical oscillations.
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Lipina C, Irving AJ, Hundal HS. Mitochondria: a possible nexus for the regulation of energy homeostasis by the endocannabinoid system? Am J Physiol Endocrinol Metab 2014; 307:E1-13. [PMID: 24801388 DOI: 10.1152/ajpendo.00100.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The endocannabinoid system (ECS) regulates numerous cellular and physiological processes through the activation of receptors targeted by endogenously produced ligands called endocannabinoids. Importantly, this signaling system is known to play an important role in modulating energy balance and glucose homeostasis. For example, current evidence indicates that the ECS becomes overactive during obesity whereby its central and peripheral stimulation drives metabolic processes that mimic the metabolic syndrome. Herein, we examine the role of the ECS in modulating the function of mitochondria, which play a pivotal role in maintaining cellular and systemic energy homeostasis, in large part due to their ability to tightly coordinate glucose and lipid utilization. Because of this, mitochondrial dysfunction is often associated with peripheral insulin resistance and glucose intolerance as well as the manifestation of excess lipid accumulation in the obese state. This review aims to highlight the different ways through which the ECS may impact upon mitochondrial abundance and/or oxidative capacity and, where possible, relate these findings to obesity-induced perturbations in metabolic function. Furthermore, we explore the potential implications of these findings in terms of the pathogenesis of metabolic disorders and how these may be used to strategically develop therapies targeting the ECS.
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Affiliation(s)
- Christopher Lipina
- Division of Cell Signalling and Immunology, Sir James Black Centre, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Andrew J Irving
- Division of Cell Signalling and Immunology, Sir James Black Centre, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
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Human immunodeficiency virus-1 Tat protein increases the number of inhibitory synapses between hippocampal neurons in culture. J Neurosci 2013; 33:17908-20. [PMID: 24198379 DOI: 10.1523/jneurosci.1312-13.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synaptodendritic damage correlates with cognitive decline in many neurodegenerative diseases, including human immunodeficiency virus-1 (HIV-1)-associated neurocognitive disorders (HAND). Because HIV-1 does not infect neurons, viral-mediated toxicity is indirect, resulting from released neurotoxins such as the HIV-1 protein transactivator of transcription (Tat). We compared the effects of Tat on inhibitory and excitatory synaptic connections between rat hippocampal neurons using an imaging-based assay that quantified clusters of the scaffolding proteins gephyrin or PSD95 fused to GFP. Tat (24 h) increased the number of GFP-gephyrin puncta and decreased the number of PSD95-GFP puncta. The effects of Tat on inhibitory and excitatory synapse number were mediated via the low-density lipoprotein receptor-related protein and subsequent Ca(2+) influx through GluN2A-containing NMDA receptors (NMDARs). The effects of Tat on synapse number required cell-autonomous activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Ca(2+) buffering experiments suggested that loss of excitatory synapses required activation of CaMKII in close apposition to the NMDAR, whereas the increase in inhibitory synapses required Ca(2+) diffusion to a more distal site. The increase in inhibitory synapses was prevented by inhibiting the insertion of GABAA receptors into the membrane. Synaptic changes induced by Tat (16 h) were reversed by blocking either GluN2B-containing NMDARs or neuronal nitric oxide synthase, indicating changing roles for pathways activated by NMDAR subtypes during the neurotoxic process. Compensatory changes in the number of inhibitory and excitatory synapses may serve as a novel mechanism to reduce network excitability in the presence of HIV-1 neurotoxins; these changes may inform the development of treatments for HAND.
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Effects of WIN 55,212-2 mesylate on the anticonvulsant action of lamotrigine, oxcarbazepine, pregabalin and topiramate against maximal electroshock-induced seizures in mice. Eur J Pharmacol 2013; 720:247-54. [PMID: 24161913 DOI: 10.1016/j.ejphar.2013.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/09/2013] [Accepted: 10/16/2013] [Indexed: 10/26/2022]
Abstract
The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN - a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four second-generation antiepileptic drugs (lamotrigine, oxcarbazepine, pregabalin and topiramate) in the mouse maximal electroshock seizure model. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2s stimulus duration) delivered via auricular electrodes. Drug-related adverse effects were ascertained by use of the chimney test (evaluating motor performance), the step-through passive avoidance task (assessing long-term memory) and the grip-strength test (evaluating skeletal muscular strength). Total brain concentrations of antiepileptic drugs were measured by high-pressure liquid chromatography to ascertain any pharmacokinetic contribution to the observed antiseizure effect. Results indicate that WIN (5mg/kg, i.p.) significantly enhanced the anticonvulsant action of lamotrigine (P<0.05), pregabalin (P<0.001) and topiramate (P<0.05), but not that of oxcarbazepine in the maximal electroshock-induced tonic seizure test in mice. Furthermore, none of the investigated combinations of WIN with antiepileptic drugs were associated with any concurrent adverse effects with regards to motor performance, long-term memory or muscular strength. Pharmacokinetic characterization revealed that WIN had no impact on total brain concentrations of lamotrigine, oxcarbazepine, pregabalin and topiramate in mice. These preclinical data would suggest that WIN in combination with lamotrigine, pregabalin and topiramate is associated with beneficial anticonvulsant pharmacodynamic interactions in the maximal electroshock-induced tonic seizure test.
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Citraro R, Russo E, Ngomba RT, Nicoletti F, Scicchitano F, Whalley BJ, Calignano A, De Sarro G. CB1 agonists, locally applied to the cortico-thalamic circuit of rats with genetic absence epilepsy, reduce epileptic manifestations. Epilepsy Res 2013; 106:74-82. [PMID: 23860329 DOI: 10.1016/j.eplepsyres.2013.06.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 06/04/2013] [Accepted: 06/18/2013] [Indexed: 12/22/2022]
Abstract
Drugs that modulate the endocannabinoid system and endocannabinoids typically play an anticonvulsant role although some proconvulsant effects have been reported both in humans and animal models. Moreover, no evidence for a role of the cannabinoid system in human absence epilepsy has been found although limited evidence of efficacy in relevant experimental animal models has been documented. This study aims to characterize the role of cannabinoids in specific areas of the cortico-thalamic network involved in oscillations that underlie seizures in a genetic animal model of absence epilepsy, the WAG/Rij rat. We assessed the effects of focal injection of the endogenous cannabinoid, anandamide (AEA), a non-selective CB receptor agonist (WIN55,212) and a selective CB1 receptor antagonist/inverse agonist (SR141716A) into thalamic nuclei and primary somatosensory cortex (S1po) of the cortico-thalamic network. AEA and WIN both reduced absence seizures independently from the brain focal site of infusion while, conversely, rimonabant increased absence seizures but only when focally administered to the ventroposteromedial thalamic nucleus (VPM). These results, together with previous reports, support therapeutic potential for endocannabinoid system modulators in absence epilepsy and highlight that attenuated endocannabinergic function may contribute to the generation and maintenance of seizures. Furthermore, the entire cortico-thalamic network responds to cannabinoid treatment, indicating that in all areas considered, CB receptor activation inhibits the pathological synchronization that subserves absence seizures. In conclusion, our result might be useful for the identification of future drug therapies in absence epilepsy.
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Affiliation(s)
- Rita Citraro
- Chair of Pharmacology, Department of Health Science, School of Medicine and Surgery, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
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Zogopoulos P, Vasileiou I, Patsouris E, Theocharis S. The neuroprotective role of endocannabinoids against chemical-induced injury and other adverse effects. J Appl Toxicol 2013; 33:246-64. [DOI: 10.1002/jat.2828] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/31/2012] [Accepted: 09/01/2012] [Indexed: 12/21/2022]
Affiliation(s)
- Panagiotis Zogopoulos
- 1st Department of Pathology, Medical School; National and Kapodistrian University of Athens; Athens; Greece
| | - Ioanna Vasileiou
- 1st Department of Pathology, Medical School; National and Kapodistrian University of Athens; Athens; Greece
| | - Efstratios Patsouris
- 1st Department of Pathology, Medical School; National and Kapodistrian University of Athens; Athens; Greece
| | - Stamatios Theocharis
- 1st Department of Pathology, Medical School; National and Kapodistrian University of Athens; Athens; Greece
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Li Y, Popko J, Krogh KA, Thayer SA. Epileptiform stimulus increases Homer 1a expression to modulate synapse number and activity in hippocampal cultures. J Neurophysiol 2012; 109:1494-504. [PMID: 23274309 DOI: 10.1152/jn.00580.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons adapt to seizure activity structurally and functionally to attenuate hyperactive neural circuits. Homer proteins provide a scaffold in the postsynaptic density (PSD) by binding to ligands through an EVH1 domain and to other Homer proteins by a coiled-coil domain. The short Homer isoform 1a (H1a) has a ligand-binding domain but lacks a coiled-coil domain and thus acts in a dominant-negative manner to uncouple Homer scaffolds. Here, we show that treating rat hippocampal cultures with bicuculline and 4-aminopyridine (Bic+4-AP) evoked epileptiform activity and synchronized Ca(2+) spiking, measured with whole cell current-clamp and fura-2-based digital imaging; Bic+4-AP increased H1a mRNA through the activation of metabotropic glutamate receptor 5 (mGluR5). Treatment with Bic+4-AP for 4 h attenuated burst firing and induced synapse loss. Synaptic changes were measured using a confocal imaging-based assay that quantified clusters of PSD-95 fused to green fluorescent protein. Treatment with an mGluR5 antagonist blocked H1a expression, synapse loss, and burst attenuation. Overexpression of H1a inhibited burst firing similar to Bic+4-AP treatment. Furthermore, knockdown of H1a using a short hairpin RNA (shRNA) strategy reduced synapse loss and burst attenuation induced by Bic+4-AP treatment. Thus an epileptiform stimulus applied to hippocampal neurons in culture induced burst firing and H1a expression through the activation of mGluR5; a 4-h exposure to this stimulus resulted in synapse loss and burst attenuation. These results suggest that H1a expression functions in a negative-feedback manner to reduce network excitability by regulating the number of synapses.
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Affiliation(s)
- Yan Li
- Dept. of Pharmacology, Univ. of Minnesota, 6-120 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA
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26
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Shin AH, Thayer SA. Human immunodeficiency virus-1 protein Tat induces excitotoxic loss of presynaptic terminals in hippocampal cultures. Mol Cell Neurosci 2012; 54:22-9. [PMID: 23267846 DOI: 10.1016/j.mcn.2012.12.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 12/07/2012] [Accepted: 12/14/2012] [Indexed: 11/15/2022] Open
Abstract
Human immunodeficiency virus (HIV) infection of the CNS produces dendritic damage that correlates with cognitive decline in patients with HIV-associated neurocognitive disorders (HAND). HIV-induced neurotoxicity results in part from viral proteins shed from infected cells, including the HIV transactivator of transcription (Tat). We previously showed that Tat binds to the low density lipoprotein receptor-related protein (LRP), resulting in overactivation of NMDA receptors, activation of the ubiquitin-proteasome pathway, and subsequent loss of postsynaptic densities. Here, we show that Tat also induces a loss of presynaptic terminals. The number of presynaptic terminals was quantified using confocal imaging of synaptophysin fused to green fluorescent protein (Syn-GFP). Tat-induced loss of presynaptic terminals was secondary to excitatory postsynaptic mechanisms because treatment with an LRP antagonist or an NMDA receptor antagonist inhibited this loss. Treatment with nutlin-3, an E3 ligase inhibitor, prevented Tat-induced loss of presynaptic terminals. These data suggest that Tat-induced loss of presynaptic terminals is a consequence of excitotoxic postsynaptic activity. We previously found that ifenprodil, an NR2B subunit-selective NMDA receptor antagonist, induced recovery of postsynaptic densities. Here we show that Tat-induced loss of presynaptic terminals was reversed by ifenprodil treatment. Thus, Tat-induced loss of presynaptic terminals is reversible, and this recovery can be initiated by inhibiting a subset of postsynaptic NMDA receptors. Understanding the dynamics of synaptic changes in response to HIV infection of the CNS may lead to the design of improved pharmacotherapies for HAND patients.
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Affiliation(s)
- Angela H Shin
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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Andres-Mach M, Zolkowska D, Barcicka-Klosowska B, Haratym-Maj A, Florek-Luszczki M, Luszczki JJ. Effect of ACEA--a selective cannabinoid CB1 receptor agonist on the protective action of different antiepileptic drugs in the mouse pentylenetetrazole-induced seizure model. Prog Neuropsychopharmacol Biol Psychiatry 2012; 39:301-9. [PMID: 22789660 DOI: 10.1016/j.pnpbp.2012.07.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 06/30/2012] [Accepted: 07/02/2012] [Indexed: 11/24/2022]
Abstract
Endogenous cannabinoid ligands and cannabinoid CB1 receptor agonists have been shown to exert anticonvulsant effects in various experimental models of epilepsy. The purpose of this study was to determine the effects of arachidonyl-2'-chloroethylamide (ACEA-a highly selective cannabinoid CB1 receptor agonist) on the protective action of clonazepam, ethosuximide, phenobarbital, and valproate against pentylenetetrazole (PTZ)-induced clonic seizures in mice. To ascertain any pharmacokinetic contribution of ACEA to the observed interactions between tested drugs, free (non-protein bound) plasma and total brain concentrations of the antiepileptic drugs were estimated. Additionally, acute adverse-effect profiles of the combination of ACEA and different classical antiepileptic drugs (clonazepam, ethosuximide, phenobarbital and valproate) with respect to motor performance, long-term memory and skeletal muscular strength were measured. Results indicated that ACEA (10mg/kg, i.p.) co-administered with phenylmethylsulfonyl fluoride (PMSF-a substance protecting ACEA against degradation by the fatty-acid hydrolase; 30mg/kg, i.p.) significantly potentiated the anticonvulsant activity of ethosuximide, phenobarbital and valproate in the mouse PTZ-induced clonic seizure model by reducing their median effective doses (ED(50) values) from 122.8mg/kg to 71.7mg/kg (P<0.01; for ethosuximide), from 13.77mg/kg to 5.26mg/kg (P<0.05; for phenobarbital), and from 142.7mg/kg to 87.3mg/kg (P<0.05; for valproate), respectively. In contrast, ACEA (10mg/kg, i.p.) in combination with PMSF (30mg/kg, i.p.) had no impact on the protective action of clonazepam against PTZ-induced seizures in mice. However, ACEA (10mg/kg)+PMSF (30mg/kg) considerably increased free plasma and total brain concentrations of ethosuximide and valproate in mice suggesting a pharmacokinetic nature of interaction between drugs. In contrast, free plasma and total brain concentrations of clonazepam and phenobarbital remained unchanged after ACEA+PMSF administration and thus, indicating pharmacodynamic interactions. Moreover, none of the examined combinations of ACEA (10mg/kg, i.p.)+PMSF (30mg/kg, i.p.) with clonazepam, ethosuximide, phenobarbital, and valproate (at their ED(50) values from the PTZ-induced seizure test) affected motor coordination in the chimney test, long-term memory in the passive avoidance task, and muscular strength in the grip-strength test in mice, indicating no possible acute adverse effects in animals. In conclusion, pharmacodynamic enhancement of the anticonvulsant potency of phenobarbital by ACEA+PMSF is worthy of recommendation for further clinical settings. Pharmacokinetic interactions of ACEA+PMSF with ethosuximide and valproate seem to be responsible for a significant suppression of PTZ-induced seizures in mice. The combination of ACEA+PMSF with clonazepam seems to be neutral from a preclinical viewpoint.
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Affiliation(s)
- Marta Andres-Mach
- Isobolographic Analysis Laboratory, Institute of Rural Health, Jaczewskiego 2, PL 20-950 Lublin, Poland
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Shin AH, Kim HJ, Thayer SA. Subtype selective NMDA receptor antagonists induce recovery of synapses lost following exposure to HIV-1 Tat. Br J Pharmacol 2012; 166:1002-17. [PMID: 22142193 DOI: 10.1111/j.1476-5381.2011.01805.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
Abstract
BACKGROUND AND PURPOSE Neurocognitive disorders afflict approximately 20% of HIV-infected patients. HIV-1-infected cells in the brain shed viral proteins such as transactivator of transcription (Tat). Tat elicits cell death and synapse loss via processes initiated by NMDA receptor activation but mediated by separate downstream signalling pathways. Subunit selective NMDA receptor antagonists may differentially modulate survival relative to synaptic changes. EXPERIMENTAL APPROACH Tat-evoked cell death was quantified by measuring propidium iodide uptake into rat hippocampal neurons in culture. The effects of Tat on synaptic changes were measured using an imaging-based assay that quantified clusters of the scaffolding protein postsynaptic density 95 fused to green fluorescent protein. KEY RESULTS Dizocilpine, a non-competitive NMDA receptor antagonist, inhibited Tat-induced synapse loss, subsequent synapse recovery and Tat-induced cell death with comparable potencies. Memantine (10 µM) and ifenprodil (10 µM), which preferentially inhibit GluN2B-containing NMDA receptors, protected from Tat-induced cell death with no effect on synapse loss. Surprisingly, memantine and ifenprodil induced synapse recovery in the presence of Tat. In contrast, the GluN2A-prefering antagonist TCN201 prevented synapse loss and recovery with no effect on cell death. CONCLUSIONS AND IMPLICATIONS Synapse loss is a protective mechanism that enables the cell to cope with excess excitatory input. Thus, memantine and ifenprodil are promising neuroprotective drugs because they spare synaptic changes and promote survival. These GluN2B-preferring drugs induced recovery from Tat-evoked synapse loss, suggesting that synaptic pharmacology changed during the neurotoxic process. NMDA receptor subtypes differentially participate in the adaptation and death induced by excitotoxic insult.
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Affiliation(s)
- A H Shin
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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29
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Sánchez A, García-Merino A. Neuroprotective agents: Cannabinoids. Clin Immunol 2012; 142:57-67. [DOI: 10.1016/j.clim.2011.02.010] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 02/03/2011] [Accepted: 02/03/2011] [Indexed: 10/18/2022]
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Luszczki JJ, Andres-Mach M, Barcicka-Klosowska B, Florek-Luszczki M, Haratym-Maj A, Czuczwar SJ. Effects of WIN 55,212-2 mesylate (a synthetic cannabinoid) on the protective action of clonazepam, ethosuximide, phenobarbital and valproate against pentylenetetrazole-induced clonic seizures in mice. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:1870-6. [PMID: 21777642 DOI: 10.1016/j.pnpbp.2011.07.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/23/2011] [Accepted: 07/06/2011] [Indexed: 11/18/2022]
Abstract
The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN - a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four classical antiepileptic drugs (AEDs: clonazepam [CZP], ethosuximide [ETS], phenobarbital [PB], and valproate [VPA]) in the mouse pentylenetetrazole (PTZ)-induced clonic seizure model. WIN (15 mg/kg, i.p.) significantly enhanced the anticonvulsant action of ETS, PB and VPA, but not that of CZP against PTZ-induced clonic seizures. The ED(50) values of ETS, PB and VPA were reduced from 148.0, 13.9 and 137.1mg/kg to 104.0, 8.3 and 85.6 mg/kg, respectively (P<0.05). WIN (5 and 10mg/kg, i.p.) had no impact on the anticonvulsant action of all studied AEDs against PTZ-induced clonic seizures. WIN (15 mg/kg, i.p.) significantly elevated total brain concentrations of ETS and VPA, but not those of CZP and PB in mice. Moreover, WIN combined with CZP, ETS, PB and VPA significantly impaired motor performance, long-term memory and muscular strength in mice subjected to the chimney, passive avoidance and grip-strength tests, respectively. Pharmacodynamic enhancement of the anticonvulsant action of PB by WIN against PTZ-induced clonic seizures is favorable from a preclinical viewpoint. Advantageous effects of WIN in combination with ETS and VPA against PTZ-induced seizures were pharmacokinetic in nature. However, WIN combined with CZP, ETS, PB and VPA impaired motor coordination and long-term memory as well as reduced skeletal muscular strength in the experimental animals.
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Affiliation(s)
- Jarogniew J Luszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland.
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Madronal N, Gruart A, Valverde O, Espadas I, Moratalla R, Delgado-Garcia JM. Involvement of Cannabinoid CB1 Receptor in Associative Learning and in Hippocampal CA3-CA1 Synaptic Plasticity. Cereb Cortex 2011; 22:550-66. [DOI: 10.1093/cercor/bhr103] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Hofmann ME, Bhatia C, Frazier CJ. Cannabinoid receptor agonists potentiate action potential-independent release of GABA in the dentate gyrus through a CB1 receptor-independent mechanism. J Physiol 2011; 589:3801-21. [PMID: 21646412 DOI: 10.1113/jphysiol.2011.211482] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We report a novel excitatory effect of cannabinoid agonists on action potential-independent GABAergic transmission in the rat dentate gyrus. Specifically, we find that both WIN55,212-2 and anandamide increase the frequency of miniature IPSCs (mIPSCs)recorded from hilar mossy cells without altering event amplitude, area, rise time, or decay. The effect of WIN55,212-2 on mIPSCs is insensitive to AM251 and preserved in CB1 −/− animals,indicating that it does not depend on activation of CB1 receptors. It is also insensitive to AM630 and unaffected by capsazepine suggesting that neither CB2 nor TRPV1 receptors are involved. Further, it is blocked by pre-incubation in suramin and by a selective protein kinase A inhibitor (H-89), and is mimicked (and occluded) by bath application of forskolin. Similar CB1 receptor-independent facilitation of exocytosis is not apparent when recording evoked IPSCs in the presence of AM251, suggesting that the exocytotic mechanism that produces WIN55,212-2 sensitive mIPSCs is distinct from that which produces CB1 sensitive and action potential-dependent release. Despite clear independence from action potentials, WIN55,212-2 mediated facilitation of mIPSCs requires calcium, and yet is insensitive to chelation of calcium in the postsynaptic cell. Finally, we demonstrate that both bath application of 2-arachidonoylglycerol(2-AG) and depolarization-induced release of endogenous cannabinoids have minimal effect on mIPSC frequency. Cumulatively, our results indicate that cannabinoid ligands can selectively facilitate action potential-independent exocytosis of GABA in the rat dentate gyrus, and further emphasize that this new cannabinoid sensitive signalling system is distinct from previously described CB1 receptor-dependent systems in numerous respects.
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Affiliation(s)
- Mackenzie E Hofmann
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
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Pertwee RG, Howlett AC, Abood ME, Alexander SPH, Di Marzo V, Elphick MR, Greasley PJ, Hansen HS, Kunos G, Mackie K, Mechoulam R, Ross RA. International Union of Basic and Clinical Pharmacology. LXXIX. Cannabinoid receptors and their ligands: beyond CB₁ and CB₂. Pharmacol Rev 2011; 62:588-631. [PMID: 21079038 DOI: 10.1124/pr.110.003004] [Citation(s) in RCA: 1188] [Impact Index Per Article: 91.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There are at least two types of cannabinoid receptors (CB(1) and CB(2)). Ligands activating these G protein-coupled receptors (GPCRs) include the phytocannabinoid Δ(9)-tetrahydrocannabinol, numerous synthetic compounds, and endogenous compounds known as endocannabinoids. Cannabinoid receptor antagonists have also been developed. Some of these ligands activate or block one type of cannabinoid receptor more potently than the other type. This review summarizes current data indicating the extent to which cannabinoid receptor ligands undergo orthosteric or allosteric interactions with non-CB(1), non-CB(2) established GPCRs, deorphanized receptors such as GPR55, ligand-gated ion channels, transient receptor potential (TRP) channels, and other ion channels or peroxisome proliferator-activated nuclear receptors. From these data, it is clear that some ligands that interact similarly with CB(1) and/or CB(2) receptors are likely to display significantly different pharmacological profiles. The review also lists some criteria that any novel "CB(3)" cannabinoid receptor or channel should fulfil and concludes that these criteria are not currently met by any non-CB(1), non-CB(2) pharmacological receptor or channel. However, it does identify certain pharmacological targets that should be investigated further as potential CB(3) receptors or channels. These include TRP vanilloid 1, which possibly functions as an ionotropic cannabinoid receptor under physiological and/or pathological conditions, and some deorphanized GPCRs. Also discussed are 1) the ability of CB(1) receptors to form heteromeric complexes with certain other GPCRs, 2) phylogenetic relationships that exist between CB(1)/CB(2) receptors and other GPCRs, 3) evidence for the existence of several as-yet-uncharacterized non-CB(1), non-CB(2) cannabinoid receptors; and 4) current cannabinoid receptor nomenclature.
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Affiliation(s)
- R G Pertwee
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK.
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Luszczki JJ, Misiuta-Krzesinska M, Florek M, Tutka P, Czuczwar SJ. Synthetic cannabinoid WIN 55,212-2 mesylate enhances the protective action of four classical antiepileptic drugs against maximal electroshock-induced seizures in mice. Pharmacol Biochem Behav 2011; 98:261-7. [PMID: 21238473 DOI: 10.1016/j.pbb.2011.01.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 12/31/2010] [Accepted: 01/08/2011] [Indexed: 11/18/2022]
Abstract
The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN--a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four classical antiepileptic drugs (carbamazepine, phenytoin, phenobarbital, and valproate) in the mouse maximal electroshock seizure (MES) model. The results indicate that WIN (10 mg/kg, i.p.) significantly enhanced the anticonvulsant action of carbamazepine, phenytoin, phenobarbital and valproate in the MES test in mice. WIN (5 mg/kg) potentiated the anticonvulsant action of carbamazepine and valproate, but not that of phenytoin or phenobarbital in the MES test in mice. However, WIN administered alone and in combination with carbamazepine, phenytoin, phenobarbital and valproate significantly reduced muscular strength in mice in the grip-strength test. In the passive avoidance task, WIN in combination with phenobarbital, phenytoin and valproate significantly impaired long-term memory in mice. In the chimney test, only the combinations of WIN with phenobarbital and valproate significantly impaired motor coordination in mice. In conclusion, WIN enhanced the anticonvulsant action of carbamazepine, phenytoin, phenobarbital and valproate in the MES test. However, the utmost caution is advised when combining WIN with classical antiepileptic drugs due to impairment of motor coordination and long-term memory and/or reduction of skeletal muscular strength that might appear during combined treatment.
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Affiliation(s)
- Jarogniew J Luszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland.
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Baek JH, Zheng Y, Darlington CL, Smith PF. Cannabinoid CB(1) receptor expression and affinity in the rat hippocampus following bilateral vestibular deafferentation. Neurosci Lett 2011; 487:330-4. [PMID: 20974221 DOI: 10.1016/j.neulet.2010.10.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 10/09/2010] [Accepted: 10/19/2010] [Indexed: 01/09/2023]
Abstract
Numerous studies have shown that bilateral vestibular deafferentation (BVD) results in spatial memory deficits and hippocampal dysfunction in rats and humans. Since cannabinoid CB(1) receptors are well known to regulate synaptic plasticity in the hippocampus, we investigated whether BVD resulted in changes in CB(1) receptor expression and affinity in the rat hippocampus at 1, 3 and 7 days post-surgery, using a combination of Western blotting and radioligand binding. Using Western blotting, we found that CB(1) receptor expression was significantly lower in BVD animals compared to sham controls only in the CA3 area across the 3 time points (P=0.03). CB(1) receptor expression decreased significantly over time for both the BVD and sham animals (P=0.000). The radioligand binding assays showed no significant change in the IC(50) of the CB(1) receptor for the cannabinoid CB(1)/CB(2) receptor agonist, WIN55,212-2. These results suggest that the CB(1) receptor down-regulates in the CA3 region of the hippocampus following BVD, but with no changes in the affinity of the CB(1) receptor for WIN55,212-2.
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Affiliation(s)
- Jean Ha Baek
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, P.O. Box 913, Dunedin, New Zealand
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Sousa VC, Assaife-Lopes N, Ribeiro JA, Pratt JA, Brett RR, Sebastião AM. Regulation of hippocampal cannabinoid CB1 receptor actions by adenosine A1 receptors and chronic caffeine administration: implications for the effects of Δ9-tetrahydrocannabinol on spatial memory. Neuropsychopharmacology 2011; 36:472-87. [PMID: 20927050 PMCID: PMC3055664 DOI: 10.1038/npp.2010.179] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The cannabinoid CB(1) receptor-mediated modulation of γ-aminobutyric acid (GABA) release from inhibitory interneurons is important for the integrity of hippocampal-dependent spatial memory. Although adenosine A(1) receptors have a central role in fine-tuning excitatory transmission in the hippocampus, A(1) receptors localized in GABAergic cells do not directly influence GABA release. CB(1) and A(1) receptors are the main targets for the effects of two of the most heavily consumed psychoactive substances worldwide: Δ(9)-tetrahydrocannabinol (THC, a CB(1) receptor agonist) and caffeine (an adenosine receptor antagonist). We first tested the hypothesis that an A(1)-CB(1) interaction influences GABA and glutamate release in the hippocampus. We found that A(1) receptor activation attenuated the CB(1)-mediated inhibition of GABA and glutamate release and this interaction was manifested at the level of G-protein activation. Using in vivo and in vitro approaches, we then investigated the functional implications of the adenosine-cannabinoid interplay that may arise following chronic caffeine consumption. Chronic administration of caffeine in mice (intraperitoneally, 3 mg/kg/day, for 15 days, >12 h before trials) led to an A(1)-mediated enhancement of the CB(1)-dependent acute disruptive effects of THC on a short-term spatial memory task, despite inducing a reduction in cortical and hippocampal CB(1) receptor number and an attenuation of CB(1) coupling with G protein. A(1) receptor levels were increased following chronic caffeine administration. This study shows that A(1) receptors exert a negative modulatory effect on CB(1)-mediated inhibition of GABA and glutamate release, and provides the first evidence of chronic caffeine-induced alterations on the cannabinoid system in the cortex and hippocampus, with functional implications in spatial memory.
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Affiliation(s)
- Vasco C Sousa
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, University of Lisbon, Lisbon, Portugal,Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Natália Assaife-Lopes
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, University of Lisbon, Lisbon, Portugal,Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Joaquim A Ribeiro
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, University of Lisbon, Lisbon, Portugal,Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Judith A Pratt
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Ros R Brett
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Ana M Sebastião
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, University of Lisbon, Lisbon, Portugal,Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal,Fac. Medicina, Inst. Farmacol. e Neurociências and Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Av. Prof. Egas Moniz, Lisbon 1649-028, Portugal. Tel: +35 121 798 5183, Fax: +35 121 799 9454, E-mail:
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Hu SSJ, Arnold A, Hutchens JM, Radicke J, Cravatt BF, Wager-Miller J, Mackie K, Straiker A. Architecture of cannabinoid signaling in mouse retina. J Comp Neurol 2010; 518:3848-66. [PMID: 20653038 DOI: 10.1002/cne.22429] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cannabinoid receptors and their ligands constitute an endogenous signaling system that is found throughout the body, including the eye. This system can be activated by Delta(9)-tetrahydrocannabinol, a major drug of abuse. Cannabinoids offer considerable therapeutic potential in modulating ocular immune and inflammatory responses and in regulating intraocular pressure. The location of cannabinoid receptor 1 (CB(1)) in the retina is known, but recently a constellation of proteins has been identified that produce and break down endocannabinoids (eCBs) and modulate CB(1) function. Localization of these proteins is critical to defining specific cannabinoid signaling circuitry in the retina. Here we show the localization of diacylglycerol lipase-alpha and -beta (DGLalpha/beta), implicated in the production of the eCB 2-arachidonoyl glycerol (2-AG); monoacylglycerol lipase (MGL) and alpha/beta-hydrolase domain 6 (ABHD6), both implicated in the breakdown of 2-AG; cannabinoid receptor-interacting protein 1a (CRIP1a), a protein that may modulate CB(1) function; and fatty acid amide hydrolase (FAAH) and N-acylethanolamine-hydrolyzing acid amidase (NAAA), which have been shown to break down the eCB anandamide and related acyl amides. Our most prominent finding was that DGLalpha is present in postsynaptic type 1 OFF cone bipolar cells juxtaposed to CB(1)-containing cone photoreceptor terminals. CRIP1a is reliably presynaptic to DGLalpha, consistent with a possible role in cannabinoid signaling, and NAAA is restricted to retinal pigment epithelium, whereas DGLbeta is limited to retinal blood vessels. These results taken together with previous anatomical and functional studies define specific cannabinoid circuitry likely to modulate eCB signaling at the first synapse of the retina as well as in the inner plexiform layer.
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Affiliation(s)
- Sherry Shu-Jung Hu
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana 47405, USA
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Straiker A, Hu SSJ, Long JZ, Arnold A, Wager-Miller J, Cravatt BF, Mackie K. Monoacylglycerol lipase limits the duration of endocannabinoid-mediated depolarization-induced suppression of excitation in autaptic hippocampal neurons. Mol Pharmacol 2009; 76:1220-7. [PMID: 19767452 DOI: 10.1124/mol.109.059030] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Depolarization-induced suppression of excitation (DSE) is a major form of cannabinoid-mediated short-term retrograde neuronal plasticity and is found in numerous brain regions. Autaptically cultured murine hippocampal neurons are an architecturally simple model for the study of cannabinoid signaling, including DSE. The transient nature of DSE--tens of seconds--is probably determined by the regulated hydrolysis of the endocannabinoid 2-arachidonoyl glycerol (2-AG). No less than five candidate enzymes have been considered to serve this role: fatty acid amide hydrolase (FAAH), cyclooxygenase-2 (COX-2), monoacylglycerol lipase (MGL), and alpha/beta-hydrolase domain (ABHD) 6 and 12. We previously found that FAAH and COX-2 do not have a role in determining the duration of autaptic DSE. In the current study, we found that two structurally distinct inhibitors of MGL [N-arachidonoyl maleimide and 4-nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate (JZL184)] prolong DSE in autaptic hippocampal neurons, whereas inhibition of ABHD6 by N-methyl-N-[[3-(4-pyridinyl)phenyl]methyl]-4'-(aminocarbonyl)[1,1'-biphenyl]-4-yl ester, carbamic acid (WWL70) had no effect. In addition, we developed antibodies against MGL and ABHD6 and determined their expression in autaptic cultures. MGL is chiefly expressed at presynaptic terminals, optimally positioned to break down 2-AG that has engaged presynaptic CB(1) receptors. ABHD6 is expressed in two distinct locations on autaptic islands, including a prominent localization in some dendrites. In summary, we provide strong pharmacological and anatomical evidence that MGL regulates DSE in autaptic hippocampal neurons and, taken together with other studies, emphasizes that endocannabinoid signaling is terminated in temporally diverse ways.
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Affiliation(s)
- Alex Straiker
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, Bloomington, IN 47405, USA.
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Lozovaya N, Min R, Tsintsadze V, Burnashev N. Dual modulation of CNS voltage-gated calcium channels by cannabinoids: Focus on CB1 receptor-independent effects. Cell Calcium 2009; 46:154-62. [PMID: 19682741 DOI: 10.1016/j.ceca.2009.07.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 07/18/2009] [Indexed: 01/13/2023]
Abstract
The neuromodulatory effects of cannabinoids in the central nervous system have mainly been associated with G-protein coupled cannabinoid receptor (CB1R) mediated inhibition of voltage-gated calcium channels (VGCCs). Numerous studies show, however, that cannabinoids can also modulate VGCCs independent of CB1R activation. Nevertheless, despite the fact that endocannabinoids have a nearly equal efficacy for direct and CB1R-mediated effects on VGCC, the role of the direct cannabinoid-VGCC interaction has been largely underestimated. In this review, we summarize recent studies on the modulation of different types of VGCCs by cannabinoids, highlight the evidence for and implications of the CB1R-independent modulation, and put forward the concept, that direct interaction of cannabinoids and VGCCs is as important in regulation of VGCCs function as the CB1R-mediated effects.
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Affiliation(s)
- Natalia Lozovaya
- Institut de Neurobiologie de la Méditerranée INSERM U, Marseille, France
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Barna I, Till I, Haller J. Blood, adipose tissue and brain levels of the cannabinoid ligands WIN-55,212 and SR-141716A after their intraperitoneal injection in mice: compound-specific and area-specific distribution within the brain. Eur Neuropsychopharmacol 2009; 19:533-41. [PMID: 19303746 DOI: 10.1016/j.euroneuro.2009.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 01/23/2009] [Accepted: 02/10/2009] [Indexed: 02/06/2023]
Abstract
Cannabinoid ligands have wide ranging neural and behavioral effects; therefore, they are of substantial therapeutic interest. The levels of cannabinoids are tightly controlled in brain infusion and in vitro methodologies, although the studied dose-ranges are extremely wide (e.g. 0.4-470 nmol in brain infusion studies). The brain levels reached after systemic administration are virtually unknown. To investigate this issue, we injected intraperitoneally (3)H-labeled WIN-55,212 and SR141716A (0.3, 1 and 3 mg/kg) and estimated their accumulation in the blood, adipose tissue and brain. Accumulation was dose-dependent. The largest amounts were found in the adipose tissue, while the levels seen in the blood and brain were approximately similar. The accumulation of SR141716A was markedly more pronounced than that of WIN-55,212 in all three tissues. The brain distribution of WIN-55,212 showed large regional differences. Such differences were significant but much smaller with SR141716A. The largest brain levels noticed after intraperitoneal injections did not exceed 2.5 nmol/g. This is larger than the brain level of the endocannabinoid anandamide but smaller than that of 2-arachidonoyl glycerol. Yet, the CB1 receptor affinity of WIN-55,212 and SR-141716A is two orders of magnitude larger than that of 2-arachidonoyl glycerol, suggesting that the exogenously administered compounds were functionally more active. Our findings also suggest that brain infusion and in vitro techniques employing considerably larger doses than 2.5 nmol should be dealt with caution. It appears that measuring brain levels after systemic injections increases our understanding of cannabinoid effects, and provides important clues for the comparison of results obtained with different methodologies.
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Affiliation(s)
- I Barna
- Institute of Experimental Medicine, 1450 Budapest, P.O. Box 67, Hungary
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Hwang J, Adamson C, Butler D, Janero DR, Makriyannis A, Bahr BA. Enhancement of endocannabinoid signaling by fatty acid amide hydrolase inhibition: a neuroprotective therapeutic modality. Life Sci 2009; 86:615-23. [PMID: 19527737 DOI: 10.1016/j.lfs.2009.06.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 05/28/2009] [Accepted: 06/03/2009] [Indexed: 12/31/2022]
Abstract
AIMS This review posits that fatty acid amide hydrolase (FAAH) inhibition has therapeutic potential against neuropathological states including traumatic brain injury; Alzheimer's, Huntington's, and Parkinson's diseases; and stroke. MAIN METHODS This proposition is supported by data from numerous in vitro and in vivo experiments establishing metabolic and pharmacological contexts for the neuroprotective role of the endogenous cannabinoid ("endocannabinoid") system and selective FAAH inhibitors. KEY FINDINGS The systems biology of endocannabinoid signaling involves two main cannabinoid receptors, the principal endocannabinoid lipid mediators N-arachidonoylethanolamine ("anandamide") (AEA) and 2-arachidonoyl glycerol (2-AG), related metabolites, and the proteins involved in endocannabinoid biosynthesis, biotransformation, and transit. The endocannabinoid system is capable of activating distinct signaling pathways on-demand in response to pathogenic events or stimuli, thereby enhancing cell survival and promoting tissue repair. Accumulating data suggest that endocannabinoid system modulation at discrete targets is a promising pharmacotherapeutic strategy for treating various medical conditions. In particular, neuronal injury activates cannabinoid signaling in the central nervous system as an intrinsic neuroprotective response. Indirect potentiation of this salutary response through pharmacological inhibition of FAAH, an endocannabinoid-deactivating enzyme, and consequent activation of signaling pathways downstream from cannabinoid receptors have been shown to promote neuronal maintenance and function. SIGNIFICANCE This therapeutic modality has the potential to offer site- and event-specific neuroprotection under conditions where endocannabinoids are being produced as part of a physiological protective mechanism. In contrast, direct application of cannabinoid receptor agonists to the central nervous system may activate CB receptors indiscriminately and invite unwanted psychotrophic effects.
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Affiliation(s)
- Jeannie Hwang
- Department of Pharmaceutical Sciences and the Neurosciences Program, University of Connecticut, Storrs, Connecticut, USA
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Human immunodeficiency virus protein Tat induces synapse loss via a reversible process that is distinct from cell death. J Neurosci 2009; 28:12604-13. [PMID: 19036954 DOI: 10.1523/jneurosci.2958-08.2008] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Human immunodeficiency virus (HIV)-1 infection of the CNS produces changes in dendritic morphology that correlate with cognitive decline in patients with HIV-1 associated dementia (HAD). Here, we investigated the effects of HIV-1 transactivator of transcription (Tat), a protein released by virus-infected cells, on synapses between hippocampal neurons using an imaging-based assay that quantified clusters of the scaffolding protein postsynaptic density 95 fused to green fluorescent protein (PSD95-GFP). Tat (24 h) decreased the number of PSD95-GFP puncta by 50 +/- 7%. The decrease was concentration-dependent (EC(50) = 6 +/- 2 ng/ml) and preceded cell death. Tat acted via the low-density lipoprotein receptor-related protein (LRP) because the specific LRP blocker, receptor associated protein (RAP), prevented the Tat-induced decrease in the number of PSD95-GFP puncta. Ca(2+) influx through the NMDA receptor was necessary for Tat-induced synapse loss. Expression of an ubiquitin ligase inhibitor protected synapses, implicating the ubiquitin-proteasome pathway. In contrast to synapse loss, Tat induced cell death (48 h) required activation of nitric oxide synthase. The ubiquitin ligase-inhibitor nutlin-3 prevented synapse loss but not cell death induced by Tat. Thus, the pathways diverged, consistent with the hypothesis that synapse loss is a mechanism to reduce excess excitatory input rather than a symptom of the neuron's demise. Furthermore, application of RAP to cultures treated with Tat for 16 h reversed synapse loss. These results suggest that the impaired network function and decreased neuronal survival produced by Tat involve distinct mechanisms and that pharmacologic targets, such as LRP, might prove useful in restoring function in HAD patients.
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Basavarajappa BS, Ninan I, Arancio O. Acute ethanol suppresses glutamatergic neurotransmission through endocannabinoids in hippocampal neurons. J Neurochem 2008; 107:1001-13. [PMID: 18796007 DOI: 10.1111/j.1471-4159.2008.05685.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ethanol exposure during fetal development is a leading cause of long-term cognitive impairments. Studies suggest that ethanol exposure have deleterious effects on the hippocampus, a brain region that is important for learning and memory. Ethanol exerts its effects, in part, via alterations in glutamatergic neurotransmission, which is critical for the maturation of neuronal circuits during development. The current literature strongly supports the growing evidence that ethanol inhibits glutamate release in the neonatal CA1 hippocampal region. However, the exact molecular mechanism responsible for this effect is not well understood. In this study, we show that ethanol enhances endocannabinoid (EC) levels in cultured hippocampal neurons, possibly through calcium pathways. Acute ethanol depresses miniature post-synaptic current (mEPSC) frequencies without affecting their amplitude. This suggests that ethanol inhibits glutamate release. The CB1 receptors (CB1Rs) present on pre-synaptic neurons are not altered by acute ethanol. The CB1R antagonist SR 141716A reverses ethanol-induced depression of mEPSC frequency. Drugs that are known to enhance the in vivo function of ECs occlude ethanol effects on mEPSC frequency. Chelation of post-synaptic calcium by EGTA antagonizes ethanol-induced depression of mEPSC frequency. The activation of CB1R with the selective agonist WIN55,212-2 also suppresses the mEPSC frequency. This WIN55,212-2 effect is similar to the ethanol effects and is reversed by SR141716A. In addition, tetani-induced excitatory post-synaptic currents (EPSCs) are depressed by acute ethanol. SR141716A significantly reverses ethanol effects on evoked EPSC amplitude in a dual recording preparation. These observations, taken together, suggest the participation of ECs as retrograde messengers in the ethanol-induced depression of synaptic activities.
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Affiliation(s)
- Balapal S Basavarajappa
- Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York, USA.
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Accorsi-Mendonça D, Almado CE, Dagostin AL, Machado BH, Leão RM. Inhibition of spontaneous neurotransmission in the nucleus of solitary tract of the rat by the cannabinoid agonist WIN 55212-2 is not via CB1 or CB2 receptors. Brain Res 2008; 1200:1-9. [DOI: 10.1016/j.brainres.2008.01.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 01/02/2008] [Accepted: 01/04/2008] [Indexed: 01/20/2023]
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45
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Biala G, Budzynska B. Calcium-dependent mechanisms of the reinstatement of nicotine-conditioned place preference by drug priming in rats. Pharmacol Biochem Behav 2008; 89:116-25. [DOI: 10.1016/j.pbb.2007.12.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 11/28/2007] [Accepted: 12/03/2007] [Indexed: 11/15/2022]
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46
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Kim HJ, Waataja JJ, Thayer SA. Cannabinoids inhibit network-driven synapse loss between hippocampal neurons in culture. J Pharmacol Exp Ther 2008; 325:850-8. [PMID: 18310474 DOI: 10.1124/jpet.107.131607] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dendritic pruning and loss of synaptic contacts are early events in many neurodegenerative diseases. These effects are dynamic and seem to differ mechanistically from the cell death process. Cannabinoids modulate synaptic activity and afford protection in some neurotoxicity models. We investigated the effects of cannabinoids on activity-induced changes in the number of synapses between rat hippocampal neurons in culture. Morphology and synapses were visualized by confocal imaging of neurons expressing DsRed2 and postsynaptic density protein 95 (PSD95) fused to enhanced green fluorescent protein (GFP). Reducing the extracellular Mg2+ concentration to 0.1 mM for 4 h induced intense synaptic activity, which decreased the number of PSD95-GFP puncta by 45 +/- 13%. Synapse loss was an early event, required activation of N-methyl-D-aspartate receptors, and was mediated by the ubiquitin-proteasome pathway. The cannabinoid receptor full agonist WIN55,212-2 [(R)-(+)-[2,3-dihydro-5-methyl-3-[(4-morpholinyl)-methyl] pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl](1-napthalenyl)-methanone monomethanesulfonate] (EC(50) = 2.5 +/- 0.5 nM) and the partial agonist Delta(9)-tetrahydrocannabinol (THC; EC(50) = 9 +/- 3 nM) inhibited PSD loss in a manner reversed by the CB1 receptor antagonist rimonabant [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-carboxamide]. The protection was mimicked by inhibition of presynaptic Ca2+ channels, and WIN55,212-2 did not prevent PSD loss elicited by direct application of glutamate, suggesting a presynaptic mechanism. Prolonged exposure to WIN55,212-2, but not THC, desensitized the protective effect. Treating cells that had undergone PSD loss with WIN55,212-2 reversed the loss and enabled recovery of a full compliment of synapses. The modulation of synaptic number by acute and prolonged exposure to cannabinoids may account for some of the effects of these drugs on the plasticity, survival, and function of neural networks.
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Affiliation(s)
- Hee Jung Kim
- Department of Pharmacology, University of Minnesota Medical School, 321 Church Street, Minneapolis, MN 55455, USA
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Nucci C, Bari M, Spanò A, Corasaniti M, Bagetta G, Maccarrone M, Morrone LA. Potential roles of (endo)cannabinoids in the treatment of glaucoma: from intraocular pressure control to neuroprotection. PROGRESS IN BRAIN RESEARCH 2008; 173:451-64. [PMID: 18929127 DOI: 10.1016/s0079-6123(08)01131-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent evidence shows that the endocannabinoid system is involved in the pathogenesis of numerous neurodegenerative diseases of the central nervous system. Pharmacologic modulation of cannabinoid receptors or the enzymes involved in the synthesis, transport, or breakdown of endogenous cannabinoids has proved to be a valid alternative to conventional treatment of these diseases. In this review, we will examine recent findings that demonstrate the involvement of the endocannabinoid system in glaucoma, a major neurodegenerative disease of the eye that is a frequent cause of blindness. Experimental findings indicate that the endocannabinoid system contributes to the control of intraocular pressure (IOP), by modulating both production and drainage of aqueous humor. There is also a growing body of evidence of the involvement of this system in mechanisms leading to the death of retinal ganglion cells, which is the end result of glaucoma. Molecules capable of interfering with the ocular endocannabinoid system could offer valid alternatives to the treatment of this disease, based not only on the reduction of IOP but also on neuroprotection.
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Affiliation(s)
- Carlo Nucci
- Ophthalmological Unit, Department of Biopathology and Diagnostic Imaging, University of Rome Tor Vergata, Rome, Italy.
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48
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Campbell VA, Gowran A. Alzheimer's disease; taking the edge off with cannabinoids? Br J Pharmacol 2007; 152:655-62. [PMID: 17828287 PMCID: PMC2190031 DOI: 10.1038/sj.bjp.0707446] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 07/03/2007] [Accepted: 08/08/2007] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease is an age-related neurodegenerative condition associated with cognitive decline. The pathological hallmarks of the disease are the deposition of beta-amyloid protein and hyperphosphorylation of tau, which evoke neuronal cell death and impair inter-neuronal communication. The disease is also associated with neuroinflammation, excitotoxicity and oxidative stress. In recent years the proclivity of cannabinoids to exert a neuroprotective influence has received substantial interest as a means to mitigate the symptoms of neurodegenerative conditions. In brains obtained from Alzheimer's patients alterations in components of the cannabinoid system have been reported, suggesting that the cannabinoid system either contributes to, or is altered by, the pathophysiology of the disease. Certain cannabinoids can protect neurons from the deleterious effects of beta-amyloid and are capable of reducing tau phosphorylation. The propensity of cannabinoids to reduce beta-amyloid-evoked oxidative stress and neurodegeneration, whilst stimulating neurotrophin expression neurogenesis, are interesting properties that may be beneficial in the treatment of Alzheimer's disease. Delta 9-tetrahydrocannabinol can also inhibit acetylcholinesterase activity and limit amyloidogenesis which may improve cholinergic transmission and delay disease progression. Targeting cannabinoid receptors on microglia may reduce the neuroinflammation that is a feature of Alzheimer's disease, without causing psychoactive effects. Thus, cannabinoids offer a multi-faceted approach for the treatment of Alzheimer's disease by providing neuroprotection and reducing neuroinflammation, whilst simultaneously supporting the brain's intrinsic repair mechanisms by augmenting neurotrophin expression and enhancing neurogenesis. The evidence supporting a potential role for the cannabinoid system as a therapeutic target for the treatment of Alzheimer's disease will be reviewed herewith.
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Affiliation(s)
- V A Campbell
- Department of Physiology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.
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Wheal AJ, Bennett T, Randall MD, Gardiner SM. Cardiovascular effects of cannabinoids in conscious spontaneously hypertensive rats. Br J Pharmacol 2007; 152:717-24. [PMID: 17700721 PMCID: PMC2190006 DOI: 10.1038/sj.bjp.0707410] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Accepted: 07/18/2007] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE In anaesthetized spontaneously hypertensive rats (SHR), there is evidence for up-regulation of cannabinoid (CB1) receptors: antagonism of CB1 receptors causes a rise in blood pressure, and administration of the endocannabinoid, anandamide, or inhibition of anandamide degradation causes hypotension. These findings have led to the suggestion that the endocannabinoid system may be a therapeutic target in hypertension. However, since the cardiovascular responses to cannabinoids are substantially influenced by anaesthesia, the purpose of this study was to assess regional haemodynamic responses to cannabinoid receptor stimulation and inhibition in conscious SHR. EXPERIMENTAL APPROACH Cardiovascular responses to i.v. administration of anandamide, the cannabinoid receptor agonist, WIN 55212-2, and the CB(1) receptor antagonist, AM 251, were measured in male SHR, Wistar Kyoto rats and outbred Wistar rats, chronically instrumented for recording renal, mesenteric and hindquarters haemodynamics in the conscious, freely-moving state. KEY RESULTS Hypotensive responses to anandamide and WIN 55212-2 only occurred in SHR, but these were relatively modest and not associated with CB1 receptor-mediated vasodilatation. In SHR only, anandamide caused bradycardia, which was inhibited by AM 251. Furthermore, a pressor response to CB1 receptor antagonism occurred only in SHR, but was not associated with vasoconstriction. Moreover, there was some evidence for CB1 receptor-mediated vasoconstrictor actions of anandamide in SHR, which was not seen in the normotensive strains. CONCLUSIONS AND IMPLICATIONS The results are consistent with activation of CB1 receptors in SHR by endogenous ligands exerting an antihypertensive effect, but the findings do not indicate enhanced CB1 receptor-mediated vasodilator mechanisms in SHR.
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Affiliation(s)
- A J Wheal
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre Nottingham NG7 2UH, UK
| | - T Bennett
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre Nottingham NG7 2UH, UK
| | - M D Randall
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre Nottingham NG7 2UH, UK
| | - S M Gardiner
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre Nottingham NG7 2UH, UK
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Németh B, Ledent C, Freund TF, Hájos N. CB1 receptor-dependent and -independent inhibition of excitatory postsynaptic currents in the hippocampus by WIN 55,212-2. Neuropharmacology 2007; 54:51-7. [PMID: 17714744 PMCID: PMC2194164 DOI: 10.1016/j.neuropharm.2007.07.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 06/27/2007] [Accepted: 07/04/2007] [Indexed: 11/18/2022]
Abstract
We investigated the effect of a synthetic cannabinoid, WIN 55,212-2 on excitatory postsynaptic currents (EPSCs) evoked by stimulation of Schaffer collaterals in CA1 pyramidal cells. Bath application of WIN 55,212-2 reduced the amplitude of EPSCs in dose-dependent manner tested between 0.01 nM and 30 μM. In rats and mice, this cannabinoid ligand inhibited excitatory synapses in two steps at the nM and μM concentrations. When the function of CB1 cannabinoid receptors (CB1R) was impaired, either by the application of a CB1R antagonist AM251, or by using CB1R knockout mice, WIN 55,212-2 in μM concentrations could still significantly reduced the amplitude of EPSCs. WIN 55,212-2 likely affected the efficacy of excitatory transmission only at presynaptic sites, since both at low and high doses the paired pulse ratio of EPSC amplitude was significantly increased. The inactive enantiomer, WIN 55,212-3, mimicked the effect of WIN 55,212-2 applied in high doses. In further experiments we found that the CB1R-independent effect of 10 μM WIN 55,212-2 at glutamatergic synapses was fully abolished, when slices were pre-treated with ω-conotoxin GVIA, but not with ω-agatoxin IVA. These data suggest that, in the hippocampus, WIN 55,212-2 reduces glutamate release from Schaffer collaterals solely via CB1Rs in the nM concentration range, whereas in μM concentrations, WIN 55,212-2 suppresses excitatory transmission, in addition to activation of CB1Rs, by directly blocking N-type voltage-gated Ca2+ channels independent of CB1Rs.
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Affiliation(s)
- Beáta Németh
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, Budapest H-1450, Hungary
| | - Catherine Ledent
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moleculaire, Universite Libre de Bruxelles, 1070 Brussels, Belgium
| | - Tamás F. Freund
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, Budapest H-1450, Hungary
| | - Norbert Hájos
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, Budapest H-1450, Hungary
- Corresponding author. Tel.: +36 1 2109 400/387; fax: +36 1 210 9412.
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