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Blest-Hopley G, Colizzi M, Giampietro V, Bhattacharyya S. Is the Adolescent Brain at Greater Vulnerability to the Effects of Cannabis? A Narrative Review of the Evidence. Front Psychiatry 2020; 11:859. [PMID: 33005157 PMCID: PMC7479242 DOI: 10.3389/fpsyt.2020.00859] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/06/2020] [Indexed: 01/01/2023] Open
Abstract
Cannabis use during the critical neurodevelopmental period of adolescence, may lead to brain structural, functional, and histological alterations that may underpin some of the longer-term behavioral and psychological harms associated with it. The endocannabinoid system performs a key regulatory and homeostatic role, that undergoes developmental changes during adolescence making it potentially more susceptible to the effects of exposure to cannabis during adolescence. Here, we synthesize evidence from human studies of adolescent cannabis users showing alterations in cognitive performance as well as in brain structure and function with relevant preclinical evidence to summarize the current state of knowledge. We also focus on the limited evidence that speaks to the hypothesis that cannabis use during adolescence, may pose a greater risk than use during adulthood, identify gaps in current evidence and suggest directions for new research. Existing literature is consistent with the association of cannabis use during adolescence and neurological changes. Adolescence cannabis users show altered functional connectivity within known functional circuits, that may underlie inefficient recruitment of brain regions, as largely increased functional activation has been observed compared to controls. This disruption in some cases may contribute to the development of adverse mental health conditions; increasing the chances or accelerating the onset, of their development. Preclinical evidence, further supports disruption from cannabis use being specific to the developmental period. Future studies are required to better investigate adolescent cannabis use with more accuracy using better defined groups or longitudinal studies and examine the permanency of these changes following caseation of use. Furthermore, research is required to identify heritable risk factors to cannabis use. There is a need for caution when considering the therapeutic potential of cannabis for adolescence and particularly in public discourse leading to potential trivialization of possible harm from cannabis use in adolescence. Current evidence indicates that adolescence is a sensitive period during which cannabis use may result in adverse neurocognitive effects that appear to show a level of permanency into adulthood.
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Affiliation(s)
- Grace Blest-Hopley
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, United Kingdom
| | - Marco Colizzi
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, United Kingdom.,Section of Psychiatry, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Italy
| | - Vincent Giampietro
- Department of Neuroimaging, Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom
| | - Sagnik Bhattacharyya
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, United Kingdom.,South London and Maudsley NHS Foundation Trust, London, United Kingdom
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Ketcherside A, Noble LJ, McIntyre CK, Filbey FM. Cannabinoid Receptor 1 Gene by Cannabis Use Interaction on CB1 Receptor Density. Cannabis Cannabinoid Res 2017; 2:202-209. [PMID: 29082317 PMCID: PMC5628563 DOI: 10.1089/can.2017.0007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Because delta-9-tetrahydrocannabinol (THC), the primary psychoactive ingredient in cannabis, binds to cannabinoid 1 (CB1) receptors, levels of CB1 protein could serve as a potential biomarker for response to THC. To date, available techniques to characterize CB1 expression and function in vivo are limited. In this study, we developed an assay to quantify CB1 in lymphocytes to determine how it relates to cannabis use in 58 daily cannabis users compared with 47 nonusers. Furthermore, we tested whether CB1 levels are associated with mutations in a single nucleotide polymorphism known to regulate CB1 functioning (i.e., rs2023239). Methods: Total protein concentration was analyzed through the Pierce BCA Protein assay kit. CB1 protein was quantified through CNR1 enzyme-linked immunosorbent assay (ELISA) kit from MyBioSource. CB1 concentration and total protein concentration were quantified and used to calculate a ratio of CB1 to total protein. Results: Inherent levels of peripheral lymphocyte CB1 were sufficient for quantification through ELISA without protein amplification. We found a group×genotype interaction such that users with the G allele had greater CB1 concentration than users with the A/A genotype, and a trend-level difference between genotypes in nonusers. Conclusions: This study demonstrates a minimally invasive technique of CB1 quantification that holds promise for the use of CB1 protein concentration, along with rs2023239 genotype, as a potential biomarker for susceptibility to cannabis use. These results suggest a gene (rs2023239 G)×environment (cannabis use) effect on CB1 density.
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Affiliation(s)
- Ariel Ketcherside
- Center for BrainHealth, University of Texas at Dallas, Dallas, Texas.,The School of Behavior and Brain Science, University of Texas at Dallas, Dallas, Texas
| | - Lindsey J Noble
- The School of Behavior and Brain Science, University of Texas at Dallas, Dallas, Texas
| | - Christa K McIntyre
- The School of Behavior and Brain Science, University of Texas at Dallas, Dallas, Texas
| | - Francesca M Filbey
- Center for BrainHealth, University of Texas at Dallas, Dallas, Texas.,The School of Behavior and Brain Science, University of Texas at Dallas, Dallas, Texas
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Ismail NIW, Jayabalan N, Mansor SM, Müller CP, Muzaimi M. Chronic mitragynine (kratom) enhances punishment resistance in natural reward seeking and impairs place learning in mice. Addict Biol 2017; 22:967-976. [PMID: 26990882 DOI: 10.1111/adb.12385] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 02/06/2016] [Accepted: 02/08/2016] [Indexed: 01/09/2023]
Abstract
Kratom (Mitragyna speciosa) is a widely abused herbal drug preparation in Southeast Asia. It is often consumed as a substitute for heroin, but imposing itself unknown harms and addictive burdens. Mitragynine is the major psychostimulant constituent of kratom that has recently been reported to induce morphine-like behavioural and cognitive effects in rodents. The effects of chronic consumption on non-drug related behaviours are still unclear. In the present study, we investigated the effects of chronic mitragynine treatment on spontaneous activity, reward-related behaviour and cognition in mice in an IntelliCage® system, and compared them with those of morphine and Δ-9-tetrahydrocannabinol (THC). We found that chronic mitragynine treatment significantly potentiated horizontal exploratory activity. It enhanced spontaneous sucrose preference and also its persistence when the preference had aversive consequences. Furthermore, mitragynine impaired place learning and its reversal. Thereby, mitragynine effects closely resembled that of morphine and THC sensitisation. These findings suggest that chronic mitragynine exposure enhances spontaneous locomotor activity and the preference for natural rewards, but impairs learning and memory. These findings confirm pleiotropic effects of mitragynine (kratom) on human lifestyle, but may also support the recognition of the drug's harm potential.
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Affiliation(s)
- Nurul Iman W. Ismail
- Department of Neurosciences, School of Medical Sciences; Universiti Sains Malaysia; Malaysia
- Centre for Neuroscience Services and Research; Universiti Sains Malaysia; Malaysia
| | - Nanthini Jayabalan
- Department of Neurosciences, School of Medical Sciences; Universiti Sains Malaysia; Malaysia
- Centre for Neuroscience Services and Research; Universiti Sains Malaysia; Malaysia
| | | | - Christian P. Müller
- Section of Addiction Medicine, Department of Psychiatry and Psychotherapy; Friedrich-Alexander-University Erlangen-Nuremberg; Germany
| | - Mustapha Muzaimi
- Department of Neurosciences, School of Medical Sciences; Universiti Sains Malaysia; Malaysia
- Centre for Neuroscience Services and Research; Universiti Sains Malaysia; Malaysia
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Panlilio LV, Justinova Z, Goldberg SR. Inhibition of FAAH and activation of PPAR: new approaches to the treatment of cognitive dysfunction and drug addiction. Pharmacol Ther 2013; 138:84-102. [PMID: 23333350 DOI: 10.1016/j.pharmthera.2013.01.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 12/21/2012] [Indexed: 12/16/2022]
Abstract
Enhancing the effects of endogenously-released cannabinoid ligands in the brain might provide therapeutic effects more safely and effectively than administering drugs that act directly at the cannabinoid receptor. Inhibitors of fatty acid amide hydrolase (FAAH) prevent the breakdown of endogenous ligands for cannabinoid receptors and peroxisome proliferator-activated receptors (PPAR), prolonging and enhancing the effects of these ligands when they are naturally released. This review considers recent research on the effects of FAAH inhibitors and PPAR activators in animal models of addiction and cognition (specifically learning and memory). These studies show that FAAH inhibitors can produce potentially therapeutic effects, some through cannabinoid receptors and some through PPAR. These effects include enhancing certain forms of learning, counteracting the rewarding effects of nicotine and alcohol, relieving symptoms of withdrawal from cannabis and other drugs, and protecting against relapse-like reinstatement of drug self-administration. Since FAAH inhibition might have a wide range of therapeutic actions but might also share some of the adverse effects of cannabis, it is noteworthy that at least one FAAH-inhibiting drug (URB597) has been found to have potentially beneficial effects but no indication of liability for abuse or dependence. Although these areas of research are new, the preliminary evidence indicates that they might lead to improved therapeutic interventions and a better understanding of the brain mechanisms underlying addiction and memory.
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Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA
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Kopczyńska B. Midcervical vagotomy precludes respiratory response to novel anti-inflammatory and anti-tumour drug arvanil in rats. Eur J Pharmacol 2010; 643:101-6. [PMID: 20599930 DOI: 10.1016/j.ejphar.2010.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 05/13/2010] [Accepted: 06/07/2010] [Indexed: 10/19/2022]
Abstract
Arvanil is a metabolically stable hybrid between anandamide and capsaicin. The present study was designed to test the role of the vagal pathway in post-arvanil respiratory and blood pressure responses. Respiratory and pressure changes evoked by an intravenous injection of arvanil were investigated in 21 urethane-chloralose anaesthetised and spontaneously breathing rats. In control neurally intact rats the effects of arvanil were checked to establish the appropriate dose of the drug. In the experimental group rats were challenged with arvanil while intact, following bilateral midcervical vagotomy and after subsequent supranodose vagotomy. In all neurally intact animals bolus injection of 0.8 mg/kg of arvanil into the right femoral vein induced a significant increase of tidal volume (+1+/-0.11 ml; P<0.01) and diaphragm activity (+1.72+/-0.1 arbitrary units; P<0.01) as well as hypertension (+31.9+/-2.9 mm Hg; P<0.001) and a fall in respiratory rate (-24.7+/-0.4 breath/min; P<0.001). Bilateral midcervical vagotomy precluded the alteration of respiratory parameters but did not eliminate blood pressure response. Arvanil-induced increase in mean arterial blood pressure still persisted after supranodose vagotomy. Results indicated that the respiratory effects evoked by arvanil administered via the peripheral circulation require intact midcervical vagi. Supranodose vagotomy failed to eliminate the hypertension evoked by arvanil.
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Affiliation(s)
- Beata Kopczyńska
- Laboratory of Respiratory Reflexes, PAS Medical Research Centre, 5 Pawińskiego St., 02-106 Warsaw, Poland.
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Bossong MG, Niesink RJM. Adolescent brain maturation, the endogenous cannabinoid system and the neurobiology of cannabis-induced schizophrenia. Prog Neurobiol 2010; 92:370-85. [PMID: 20624444 DOI: 10.1016/j.pneurobio.2010.06.010] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 05/15/2010] [Accepted: 06/30/2010] [Indexed: 12/13/2022]
Abstract
Cannabis use during adolescence increases the risk of developing psychotic disorders later in life. However, the neurobiological processes underlying this relationship are unknown. This review reports the results of a literature search comprising various neurobiological disciplines, ultimately converging into a model that might explain the neurobiology of cannabis-induced schizophrenia. The article briefly reviews current insights into brain development during adolescence. In particular, the role of the excitatory neurotransmitter glutamate in experience-dependent maturation of specific cortical circuitries is examined. The review also covers recent hypotheses regarding disturbances in strengthening and pruning of synaptic connections in the prefrontal cortex, and the link with latent psychotic disorders. In the present model, cannabis-induced schizophrenia is considered to be a distortion of normal late postnatal brain maturation. Distortion of glutamatergic transmission during critical periods may disturb prefrontal neurocircuitry in specific brain areas. Our model postulates that adolescent exposure to Δ9-tetrahydrocannabinol (THC), the primary psychoactive substance in cannabis, transiently disturbs physiological control of the endogenous cannabinoid system over glutamate and GABA release. As a result, THC may adversely affect adolescent experience-dependent maturation of neural circuitries within prefrontal cortical areas. Depending on dose, exact time window and duration of exposure, this may ultimately lead to the development of psychosis or schizophrenia. The proposed model provides testable hypotheses which can be addressed in future studies, including animal experiments, reanalysis of existing epidemiological data, and prospective epidemiological studies in which the role of the dose-time-effect relationship should be central.
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Affiliation(s)
- Matthijs G Bossong
- Rudolf Magnus Institute of Neuroscience, Department of Neurology and Neurosurgery, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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Fan N, Yang H, Zhang J, Chen C. Reduced expression of glutamate receptors and phosphorylation of CREB are responsible for in vivo Delta9-THC exposure-impaired hippocampal synaptic plasticity. J Neurochem 2009; 112:691-702. [PMID: 19912468 DOI: 10.1111/j.1471-4159.2009.06489.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chronic use of marijuana impairs synaptic plasticity and cognitive function. However, the molecular mechanisms by which marijuana alters long-term synaptic plasticity are largely unknown. Here, we show that repeated in vivo exposures to Delta9-THC for 7 consecutive days significantly impaired hippocampal long-term potentiation (LTP) of excitatory glutamatergic synaptic transmission. The Delta9-THC exposure-induced decrease in LTP was prevented by pharmacological inhibition or deletion of the cannabinoid 1 receptor (CB1R). To determine the molecular mechanisms underlying Delta9-THC-altered LTP, we targeted expression and function of the glutamate receptors (GluR) and phosphorylation status of cAMP-response element-binding protein (CREB). Chronic in vivo exposure to Delta9-THC produced CB1R-dependent decreases in expression of hippocampal GluR1, NR2A, and NR2B, the ratio of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/NMDA receptor-gated currents, and phosphorylation of CREB. Our results suggest that reduced expression and function of the GluR subunits and phosphorylation of CREB may underlie the impaired long-term synaptic plasticity induced by repeated in vivo exposure to Delta9-THC.
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Affiliation(s)
- Ni Fan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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8
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Grimwood S, Hartig PR. Target site occupancy: Emerging generalizations from clinical and preclinical studies. Pharmacol Ther 2009; 122:281-301. [DOI: 10.1016/j.pharmthera.2009.03.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 01/17/2023]
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9
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Giroud C, Bollmann M, Thomas A, Mangin P, Favrat B. Consommation de cannabis: quels sont les risques ? ACTA ACUST UNITED AC 2009. [DOI: 10.1051/ata/2009021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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10
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Abstract
Many drugs of abuse, including cannabinoids, opioids, alcohol and nicotine, can alter the levels of endocannabinoids in the brain. Recent studies show that release of endocannabinoids in the ventral tegmental area can modulate the reward-related effects of dopamine and might therefore be an important neurobiological mechanism underlying drug addiction. There is strong evidence that the endocannabinoid system is involved in drug-seeking behavior (especially behavior that is reinforced by drug-related cues), as well as in the mechanisms that underlie relapse to drug use. The cannabinoid CB(1) antagonist/inverse agonist rimonabant has been shown to reduce the behavioral effects of stimuli associated with drugs of abuse, including nicotine, alcohol, cocaine, and marijuana. Thus, the endocannabinoid system represents a promising target for development of new treatments for drug addiction.
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Affiliation(s)
- Zuzana Justinova
- Department of Health and Human Services, Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Kopczyńska B. Role of VR1 and CB1 receptors in modelling of cardio-respiratory response to arvanil, an endocannabinoid and vanilloid hybrid, in rats. Life Sci 2008; 83:85-91. [DOI: 10.1016/j.lfs.2008.04.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 04/04/2008] [Accepted: 04/04/2008] [Indexed: 10/22/2022]
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12
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Rawls SM, Schroeder JA, Ding Z, Rodriguez T, Zaveri N. NOP receptor antagonist, JTC-801, blocks cannabinoid-evoked hypothermia in rats. Neuropeptides 2007; 41:239-47. [PMID: 17512052 DOI: 10.1016/j.npep.2007.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 03/14/2007] [Accepted: 03/19/2007] [Indexed: 11/15/2022]
Abstract
The present study used the endpoint of hypothermia to investigate cannabinoid and nociceptin/orphanin FQ (N/OFQ) interactions in conscious animals. Prior work has established that cannabinoids produce hypothermia by activating central cannabinoid CB(1) receptors. The administration of N/OFQ into the brain also causes significant hypothermia. Those data suggest a link between cannabinoid CB(1) receptors and N/OFQ peptide (NOP) receptors in the production of hypothermia. Therefore, we determined if NOP receptor activation is required for cannabinoid-evoked hypothermia and if cannabinoid CB(1) receptor activation is necessary for N/OFQ-induced hypothermia. In actual experiments, a cannabinoid agonist, WIN 55212-2 (2.5, 5, and 10 mg/kg, i.p.), caused significant hypothermia in male Sprague-Dawley rats (200-225 g). A NOP receptor antagonist, JTC-801 (1 mg/kg, i.p.), did not affect body temperature. For combined administration, JTC-801 (1 mg/kg, i.p.) blocked a significant proportion of the hypothermia caused by each dose of WIN 55212-2 (2.5, 5, and 10 mg/kg, i.p.). JTC-801 (1 mg/kg, i.p.) also blocked the hypothermia caused by another cannabinoid agonist, CP-55, 940 (1 mg/kg, i.p.). In separate experiments, the direct administration of N/OFQ (9 microg/rat, i.c.v.) into the brain produced significant hypothermia. The hypothermic effect of N/OFQ was blocked by JTC-801 (1 mg/kg, i.p.) but not by a selective cannabinoid CB(1) antagonist, SR 141716A (5 mg/kg, i.m.). The finding that a NOP receptor antagonist abolishes a significant percentage of cannabinoid-induced hypothermia suggests that NOP receptor activation is required for cannabinoids to produce hypothermia. This interaction, quantitated in the present study, is the first evidence that NOP receptors mediate a cannabinoid-induced effect in conscious animals.
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Affiliation(s)
- Scott M Rawls
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy and Center for Substance Abuse Research, 3307 North Broad Street, Philadelphia, PA 19140, USA.
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Dagon Y, Avraham Y, Ilan Y, Mechoulam R, Berry EM. Cannabinoids ameliorate cerebral dysfunction following liver failure
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AMP‐activated protein kinase. FASEB J 2007; 21:2431-41. [PMID: 17431095 DOI: 10.1096/fj.06-7705com] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric disorder of complex pathogenesis caused by acute or chronic liver failure. We studied the etiology of cerebral dysfunction in a murine model of HE induced by either bile duct ligation or thioacetamide administration. We report that stimulation of cerebral AMP-activated protein kinase (AMPK), a major intracellular energy sensor, is a compensatory response to liver failure. This function of AMPK is regulated by endocannabinoids. The cannabinoid system controls systemic energy balance via the cannabinoid receptors CB-1 and CB-2. Under normal circumstances, AMPK activity is mediated by CB-1 while CB-2 is barely detected. However, CB-2 is strongly stimulated in response to liver failure. Administration of delta9-tetrahydrocannabinol (THC) augmented AMPK activity and restored brain function in WT mice but not in their CB-2 KO littermates. These results suggest that HE is a disease of energy flux. CB-2 signaling is a cerebral stress response mechanism and makes AMPK a promising target for its treatment by modulating the cannabinoid system.
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Affiliation(s)
- Yossi Dagon
- Department of Human Nutrition and Metabolism, Braun School of Public Health, Faculty of Medicine Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Villares J. Chronic use of marijuana decreases cannabinoid receptor binding and mRNA expression in the human brain. Neuroscience 2007; 145:323-34. [PMID: 17222515 DOI: 10.1016/j.neuroscience.2006.11.012] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 11/07/2006] [Accepted: 11/08/2006] [Indexed: 10/23/2022]
Abstract
Chronic exposure to Cannabis sativa (marijuana) produced a significant down-regulation of cannabinoid receptor in the postmortem human brain. The significant decrease in maximal binding capacity was not accompanied by changes in the affinity constant. [3H]SR141716A binding was reduced in the caudate nucleus, putamen and in the accumbens nucleus. A significant decrease of binding sites was seen in the globus pallidus. Also in the ventral tegmental area and substantia nigra pars reticulata quantitative analysis of the density of receptors shows a significant reduction in [3H]SR141716A binding. In Cannabis sativa user brains, compared with normal brains [3H]SR141716A binding was reduced only in the hippocampus. The density of cannabinoid receptor 1 mRNA-positive neurons was significantly lower in Cannabis sativa users than in control brains for the caudate nucleus, putamen, accumbens nucleus and hippocampal region (CA1-CA4, areas of Ammon's horn). No hybridization was seen in the mesencephalon and globus pallidus.
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Affiliation(s)
- J Villares
- Universidade Federal de São Paulo, Aging and Neurodegenerative Diseases Brain Bank Laboratory, Department of Psychobiology, Rua Botucatu n. 862, Biological Science Building, São Paulo SP, Brazil, CEP 04023-062.
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Rawls SM, Tallarida RJ, Zisk J. Agmatine and a cannabinoid agonist, WIN 55212-2, interact to produce a hypothermic synergy. Eur J Pharmacol 2006; 553:89-98. [PMID: 17109846 DOI: 10.1016/j.ejphar.2006.08.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 08/03/2006] [Accepted: 08/14/2006] [Indexed: 10/24/2022]
Abstract
Agmatine blocks morphine withdrawal symptoms and enhances morphine analgesia in rats. Yet, the role of agmatine in the pharmacological effects of other abused drugs has not been investigated. The present study investigates the effect of agmatine administration on the hypothermic response to cannabinoids. Hypothermia is an effective endpoint because cannabinoid agonists produce a rapid, reproducible, and significant decrease in body temperature that is abolished by cannabinoid CB(1) receptor antagonists. WIN 55212-2, a cannabinoid agonist, was administered to rats by itself and with agmatine. WIN 55212-2 (1, 2.5, 5 and 10 mg/kg, i.m.) caused a significant hypothermia. Agmatine (10, 25 and 50 mg/kg, i.p.) was ineffective. For combined administration, agmatine (50 mg/kg, i.p.) enhanced the hypothermic effect of WIN 55212-2 (1, 2.5, 5 and 10 mg/kg, i.m.). The enhancement was strongly synergistic, indicated by a 2.7-fold increase in the relative potency of WIN 55212-2. The central administration of agmatine (25 and 50 mug/rat, i.c.v.) significantly increased the hypothermic effect of WIN 55212-2 (2.5 mg/kg, i.m.). This indicates that agmatine acts through a central mechanism to augment cannabinoid-evoked hypothermia. Idazoxan (2 mg/kg, i.p.), an imidazoline antagonist, blocked the enhancement by agmatine, thus suggesting that imidazoline receptor activation is required for agmatine to enhance cannabinoid-evoked hypothermia. The present data reveal that agmatine and a cannabinoid agonist interact to produce a hypothermic synergy in rats. These results show that agmatine acts in the brain and via imidazoline receptors to enhance cannabinoid-evoked hypothermia.
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Affiliation(s)
- Scott M Rawls
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, 3307 North Broad Street, Philadelphia, PA, 19140, USA.
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Nalwalk JW, Svokos K, Hough LB. Cannabinoid-improgan cross-tolerance: Improgan is a cannabinomimetic analgesic lacking affinity at the cannabinoid CB1 receptor. Eur J Pharmacol 2006; 549:79-83. [PMID: 16989809 DOI: 10.1016/j.ejphar.2006.08.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 08/04/2006] [Accepted: 08/14/2006] [Indexed: 10/24/2022]
Abstract
Improgan is a non-opioid analgesic which does not act at known histamine or cannabinoid receptors. Because improgan antinociception is blocked by low doses of a cannabinoid CB1 antagonist, the present experiments determined if development of cannabinoid tolerance in mice would alter improgan antinociception. Twice-daily injections of Delta9-tetrahydrocannabinol (THC, 10 mg/kg, s.c.) for 3.5 days induced 47-54% and 42-56% reductions in cannabinoid (WIN 55,212-2, 20 microg, i.c.v.) and improgan (30 microg, i.c.v.) antinociception, respectively, as compared with responses from vehicle-treated groups. Because improgan lacks cannabinoid-like side effects in rats, and does not act directly on cannabinoid CB1 receptors, the finding that development of cannabinoid tolerance reduces improgan antinociception suggests that this drug may release endocannabinoids, or activate novel cannabinoid sites. Either possibility offers the potential for developing new types of analgesics.
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Affiliation(s)
- Julia W Nalwalk
- Center for Neuropharmacology and Neuroscience, Albany Medical College MC-136, Albany, NY 12208, USA
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