1
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Ornelas LC, Besheer J. Predator odor stress reactivity, alcohol drinking and the endocannabinoid system. Neurobiol Stress 2024; 30:100634. [PMID: 38623398 PMCID: PMC11016807 DOI: 10.1016/j.ynstr.2024.100634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/26/2024] [Accepted: 03/30/2024] [Indexed: 04/17/2024] Open
Abstract
Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are highly comorbid and individual differences in response to stress suggest resilient and susceptible populations. Using animal models to target neurobiological mechanisms associated with individual variability in stress coping responses and the relationship with subsequent increases in alcohol consumption has important implications for the field of traumatic stress and alcohol disorders. The current review discusses the unique advantages of utilizing predator odor stressor exposure models, specifically using 2,5-dihydro-2,4,5-trimethylthiazoline (TMT) on better understanding PTSD pathophysiology and neurobiological mechanisms associated with stress reactivity and subsequent increases in alcohol drinking. Furthermore, there has been increasing interest regarding the role of the endocannabinoid system in modulating behavioral responses to stress with an emphasis on stress coping and individual differences in stress-susceptibility. Therefore, the current review focuses on the topic of endocannabinoid modulation of stress reactive behaviors during and after exposure to a predator odor stressor, with implications on modulating distinctly different behavioral coping strategies.
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Affiliation(s)
- Laura C. Ornelas
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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2
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Hill MN, Haney M, Hillard CJ, Karhson DS, Vecchiarelli HA. The endocannabinoid system as a putative target for the development of novel drugs for the treatment of psychiatric illnesses. Psychol Med 2023; 53:7006-7024. [PMID: 37671673 PMCID: PMC10719691 DOI: 10.1017/s0033291723002465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 07/25/2023] [Accepted: 07/28/2023] [Indexed: 09/07/2023]
Abstract
Cannabis is well established to impact affective states, emotion and perceptual processing, primarily through its interactions with the endocannabinoid system. While cannabis use is quite prevalent in many individuals afflicted with psychiatric illnesses, there is considerable controversy as to whether cannabis may worsen these conditions or provide some form of therapeutic benefit. The development of pharmacological agents which interact with components of the endocannabinoid system in more localized and discrete ways then via phytocannabinoids found in cannabis, has allowed the investigation if direct targeting of the endocannabinoid system itself may represent a novel approach to treat psychiatric illness without the potential untoward side effects associated with cannabis. Herein we review the current body of literature regarding the various pharmacological tools that have been developed to target the endocannabinoid system, their impact in preclinical models of psychiatric illness and the recent data emerging of their utilization in clinical trials for psychiatric illnesses, with a specific focus on substance use disorders, trauma-related disorders, and autism. We highlight several candidate drugs which target endocannabinoid function, particularly inhibitors of endocannabinoid metabolism or modulators of cannabinoid receptor signaling, which have emerged as potential candidates for the treatment of psychiatric conditions, particularly substance use disorder, anxiety and trauma-related disorders and autism spectrum disorders. Although there needs to be ongoing clinical work to establish the potential utility of endocannabinoid-based drugs for the treatment of psychiatric illnesses, the current data available is quite promising and shows indications of several potential candidate diseases which may benefit from this approach.
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Affiliation(s)
- Matthew N. Hill
- Departments of Cell Biology and Anatomy & Psychiatry, Cumming School of Medicine, Hotchkiss Brain Institute and The Mathison Centre for Mental Health Research and Education, University of Calgary, Calgary, Canada
| | - Margaret Haney
- Department of Psychiatry, New York State Psychiatric Institute and Columbia University Irving Medical Center, New York, USA
| | - Cecilia J. Hillard
- Department of Pharmacology and Toxicology, Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, USA
| | - Debra S. Karhson
- Department of Psychology, University of New Orleans, New Orleans, USA
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3
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Haller J. Anxiety Modulation by Cannabinoids-The Role of Stress Responses and Coping. Int J Mol Sci 2023; 24:15777. [PMID: 37958761 PMCID: PMC10650718 DOI: 10.3390/ijms242115777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
Endocannabinoids were implicated in a variety of pathological conditions including anxiety and are considered promising new targets for anxiolytic drug development. The optimism concerning the potentials of this system for anxiolysis is probably justified. However, the complexity of the mechanisms affected by endocannabinoids, and discrepant findings obtained with various experimental approaches makes the interpretation of research results difficult. Here, we review the anxiety-related effects of the three main interventions used to study the endocannabinoid system: pharmacological agents active at endocannabinoid-binding sites present on both the cell membrane and in the cytoplasm, genetic manipulations targeting cannabinoid receptors, and function-enhancers represented by inhibitors of endocannabinoid degradation and transport. Binding-site ligands provide inconsistent findings probably because they activate a multitude of mechanisms concomitantly. More robust findings were obtained with genetic manipulations and particularly with function enhancers, which heighten ongoing endocannabinoid activation rather than affecting all mechanisms indiscriminately. The enhancement of ongoing activity appears to ameliorate stress-induced anxiety without consistent effects on anxiety in general. Limited evidence suggests that this effect is achieved by promoting active coping styles in critical situations. These findings suggest that the functional enhancement of endocannabinoid signaling is a promising drug development target for stress-related anxiety disorders.
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Affiliation(s)
- József Haller
- Drug Research Institute, 1137 Budapest, Hungary;
- Department of Criminal Psychology, University of Public Service, 1082 Budapest, Hungary
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4
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Kruk-Slomka M, Adamski B, Slomka T, Biala G. Inhibitors of Endocannabinoids' Enzymatic Degradation as a Potential Target of the Memory Disturbances in an Acute N-Methyl-D-Aspartate (NMDA) Receptor Hypofunction Model of Schizophrenia in Mice. Int J Mol Sci 2023; 24:11400. [PMID: 37511157 PMCID: PMC10380236 DOI: 10.3390/ijms241411400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/08/2023] [Accepted: 07/11/2023] [Indexed: 07/30/2023] Open
Abstract
Treating schizophrenia with the available pharmacotherapy is difficult. One possible strategy is focused on the modulation of the function of the endocannabinoid system (ECS). The ECS is comprised of cannabinoid (CB) receptors, endocannabinoids and enzymes responsible for the metabolism of endocannabinoids (fatty acid hydrolase (FAAH) and monoacylglycerol lipase (MAGL)). Here, the aim of the experiments was to evaluate the impact of inhibitors of endocannabinoids' enzymatic degradation in the brain: KML-29 (MAGL inhibitor), JZL-195 (MAGL/FAAH inhibitor) and PF-3845 (FAAH inhibitor), on the memory disturbances typical for schizophrenia in an acute N-methyl-D-aspartate (NMDA) receptor hypofunction animal model of schizophrenia (i.e., injection of MK-801, an NMDA receptor antagonist). The memory-like responses were assessed in the passive avoidance (PA) test. A single administration of KML-29 or PF-3845 had a positive effect on the memory processes, but an acute administration of JZL-195 impaired cognition in mice in the PA test. Additionally, the combined administration of a PA-ineffective dose of KML-29 (5 mg/kg) or PF-3845 (3 mg/kg) attenuated the MK-801-induced cognitive impairment (0.6 mg/kg). Our results suggest that the indirect regulation of endocannabinoids' concentration in the brain through the use of selected inhibitors may positively affect memory disorders, and thus increase the effectiveness of modern pharmacotherapy of schizophrenia.
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Affiliation(s)
- Marta Kruk-Slomka
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, 4a Chodzki Street, 20-093 Lublin, Poland
| | - Bartlomiej Adamski
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, 4a Chodzki Street, 20-093 Lublin, Poland
| | - Tomasz Slomka
- Department of Medical Informatics and Statistics with E-Health Lab, Medical University of Lublin, Jaczewskiego 4 Street, 20-954 Lublin, Poland
| | - Grazyna Biala
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, 4a Chodzki Street, 20-093 Lublin, Poland
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5
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Ahluwalia M, Mcmichael H, Kumar M, Espinosa MP, Bosomtwi A, Lu Y, Khodadadi H, Jarrahi A, Khan MB, Hess DC, Rahimi SY, Vender JR, Vale FL, Braun M, Baban B, Dhandapani KM, Vaibhav K. Altered endocannabinoid metabolism compromises the brain-CSF barrier and exacerbates chronic deficits after traumatic brain injury in mice. Exp Neurol 2023; 361:114320. [PMID: 36627040 PMCID: PMC9904276 DOI: 10.1016/j.expneurol.2023.114320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/07/2022] [Accepted: 01/06/2023] [Indexed: 01/09/2023]
Abstract
Endocannabinoids [2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA)], endogenously produced arachidonate-based lipids, are anti-inflammatory physiological ligands for two known cannabinoid receptors, CB1 and CB2, yet the molecular and cellular mechanisms underlying their effects after brain injury are poorly defined. In the present study, we hypothesize that traumatic brain injury (TBI)-induced loss of endocannabinoids exaggerates neurovascular injury, compromises brain-cerebrospinal fluid (CSF) barriers (BCB) and causes behavioral dysfunction. Preliminary analysis in human CSF and plasma indicates changes in endocannabinoid levels. This encouraged us to investigate the levels of endocannabinoid-metabolizing enzymes in a mouse model of controlled cortical impact (CCI). Reductions in endocannabinoid (2-AG and AEA) levels in plasma were supported by higher expression of their respective metabolizing enzymes, monoacylglycerol lipase (MAGL), fatty acid amide hydrolase (FAAH), and cyclooxygenase 2 (Cox-2) in the post-TBI mouse brain. Following increased metabolism of endocannabinoids post-TBI, we observed increased expression of CB2, non-cannabinoid receptor Transient receptor potential vanilloid-1 (TRPV1), aquaporin 4 (AQP4), ionized calcium binding adaptor molecule 1 (IBA1), glial fibrillary acidic protein (GFAP), and acute reduction in cerebral blood flow (CBF). The BCB and pericontusional cortex showed altered endocannabinoid expressions and reduction in ventricular volume. Finally, loss of motor functions and induced anxiety behaviors were observed in these TBI mice. Taken together, our findings suggest endocannabinoids and their metabolizing enzymes play an important role in the brain and BCB integrity and highlight the need for more extensive studies on these mechanisms.
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Affiliation(s)
- Meenakshi Ahluwalia
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Hannah Mcmichael
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Manish Kumar
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Mario P Espinosa
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Asamoah Bosomtwi
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Yujiao Lu
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Hesam Khodadadi
- Department of Oral Biology and Diagnostic Sciences, Center for Excellence in Research, Scholarship and Innovation, Dental College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Abbas Jarrahi
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Mohammad Badruzzaman Khan
- Department of Neurology, Neuroscience Center of Excellence, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - David C Hess
- Department of Neurology, Neuroscience Center of Excellence, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Scott Y Rahimi
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - John R Vender
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Fernando L Vale
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Molly Braun
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America; Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA, United States of America; VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, Seattle, WA, United States of America
| | - Babak Baban
- Department of Oral Biology and Diagnostic Sciences, Center for Excellence in Research, Scholarship and Innovation, Dental College of Georgia, Augusta University, Augusta, GA, United States of America; Department of Neurology, Neuroscience Center of Excellence, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Krishnan M Dhandapani
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America
| | - Kumar Vaibhav
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, United States of America; Department of Oral Biology and Diagnostic Sciences, Center for Excellence in Research, Scholarship and Innovation, Dental College of Georgia, Augusta University, Augusta, GA, United States of America.
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6
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Crombie KM, Privratsky AA, Schomaker CM, Heilicher M, Ross MC, Sartin-Tarm A, Sellnow K, Binder EB, Andrew James G, Cisler JM. The influence of FAAH genetic variation on physiological, cognitive, and neural signatures of fear acquisition and extinction learning in women with PTSD. Neuroimage Clin 2022; 33:102922. [PMID: 34952353 PMCID: PMC8715233 DOI: 10.1016/j.nicl.2021.102922] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 12/14/2022]
Abstract
PTSD is often treated with psychotherapies based on principles of fear acquisition and extinction. Increased AEA has resulted in enhanced extinction learning and recall among healthy adults. These effects have not yet been comprehensively examined in a PTSD population. Results suggest that genetic variation within the FAAH gene affects how fear learning is tuned in women with PTSD.
Background Posttraumatic Stress Disorder (PTSD) is commonly treated with exposure-based cognitive therapies that are based on the principles of fear acquisition and extinction learning. Elevations in one of the major endocannabinoids (anandamide) either via inhibition of the primary degrading enzyme (fatty acid amide hydrolase; FAAH) or via a genetic variation in the FAAH gene (C385A; rs324420) has resulted in accelerated extinction learning and enhanced extinction recall among healthy adults. These results suggest that targeting FAAH may be a promising therapeutic approach for PTSD. However, these effects have not yet been comprehensively examined in a PTSD population. Methods The current study examined whether genetic variation in the FAAH gene (CC [n = 49] vs AA/AC [n = 36] allele carriers) influences physiological (skin conductance), cognitive (threat expectancy), and neural (network and voxel-wise activation) indices of fear acquisition and extinction learning among a sample of adult women with PTSD (N = 85). Results The physiological, cognitive, and neural signatures of fear acquisition and extinction learning varied as a function of whether or not individuals possess the FAAH C385A polymorphism. For instance, we report divergent responding between CC and AA/AC allele carriers to CS + vs CS- in limbic and striatum networks and overall greater activation throughout the task among AA/AC allele carriers in several regions [e.g., inferior frontal, middle frontal, parietal] that are highly consistent with a frontoparietal network involved in higher-order executive functions. Conclusions These results suggest that genetic variation within the FAAH gene influences physiological, cognitive, and neural signatures of fear learning in women with PTSD. In order to advance our understanding of the efficacy of FAAH inhibition as a treatment for PTSD, future clinical trials in this area should assess genetic variation in the FAAH gene in order to fully depict and differentiate the acute effects of a drug manipulation (FAAH inhibition) from more chronic (genetic) influences on fear extinction processes.
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Affiliation(s)
- Kevin M Crombie
- The University of Texas at Austin, Department of Psychiatry and Behavioral Sciences, Health Discovery Building, 1601 Trinity St., Building B, Austin, TX 78712, USA.
| | - Anthony A Privratsky
- University of Arkansas for Medical Sciences, Brain Imaging Research Center, 4301 W. Markham Street #554, Little Rock, AR 72205, USA
| | - Chloe M Schomaker
- The University of Texas at Austin, Department of Psychiatry and Behavioral Sciences, Health Discovery Building, 1601 Trinity St., Building B, Austin, TX 78712, USA
| | - Mickela Heilicher
- University of Wisconsin - Madison, Department of Psychiatry, 6001 Research Park Boulevard, Madison, WI 53719-1176608-262-6375, USA
| | - Marisa C Ross
- University of Wisconsin - Madison, Department of Psychiatry, 6001 Research Park Boulevard, Madison, WI 53719-1176608-262-6375, USA
| | - Anneliis Sartin-Tarm
- University of Wisconsin - Madison, Department of Psychiatry, 6001 Research Park Boulevard, Madison, WI 53719-1176608-262-6375, USA
| | - Kyrie Sellnow
- University of Wisconsin - Madison, Department of Psychiatry, 6001 Research Park Boulevard, Madison, WI 53719-1176608-262-6375, USA
| | - Elisabeth B Binder
- Max Planck Institute of Psychiatry, Department of Translational Psychiatry, Kraepelinstr. 2-10, 80804, Munchen, Germany; Emory University, Department of Psychiatry and Behavioral Sciences, 12 Executive Park Dr NE #200, Atlanta, GA 30329, USA
| | - G Andrew James
- University of Arkansas for Medical Sciences, Brain Imaging Research Center, 4301 W. Markham Street #554, Little Rock, AR 72205, USA
| | - Josh M Cisler
- The University of Texas at Austin, Department of Psychiatry and Behavioral Sciences, Health Discovery Building, 1601 Trinity St., Building B, Austin, TX 78712, USA
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7
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Kolla NJ, Boileau I, Bagby RM. Higher trait neuroticism is associated with greater fatty acid amide hydrolase binding in borderline and antisocial personality disorders. Sci Rep 2022; 12:1126. [PMID: 35064143 PMCID: PMC8782862 DOI: 10.1038/s41598-022-04789-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 12/31/2021] [Indexed: 11/20/2022] Open
Abstract
Borderline personality disorder (BPD) and antisocial personality disorder (ASPD) are the two most frequently diagnosed and researched DSM-5 personality disorders, and both are characterized by high levels of trait neuroticism. Fatty acid amide hydrolase (FAAH), an enzyme of the endocannabinoid system (ECS), has been linked to regulation of mood through modulation of anandamide, an endocannabinoid. We hypothesized that prefrontal cortex (PFC) FAAH binding would relate to trait neuroticism in personality disorders. Thirty-one individuals with personality disorders (20 with BPD and 11 with ASPD) completed the investigation. All participants completed the revised NEO Personality Inventory, which yields standardized scores (e.g., T scores) for the traits of neuroticism, openness, conscientiousness, agreeableness, and extraversion. All participants were medication free and were not utilizing illicit substances as determined by drug urinalysis. Additionally, none of the participants had a comorbid major depressive episode, bipolar disorder, psychotic disorder, or substance use disorder. Each participant underwent one [11C]CURB PET scan. Consistent with our hypothesis, neuroticism was positively correlated with PFC FAAH binding (r = 0.42, p = 0.021), controlling for genotype. Neuroticism was also positively correlated with dorsal putamen FAAH binding (r = 0.53, p = 0.0024), controlling for genotype. Elevated brain FAAH is an endophenotype for high neuroticism in BPD and ASPD. Novel pharmacological therapeutics that inhibit FAAH could emerge as potential new treatments for BPD and ASPD with high neuroticism.
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Affiliation(s)
- Nathan J Kolla
- Centre for Addiction and Mental Health (CAMH), 250 College Street, Room 626, Toronto, ON, M5T 1R8, Canada. .,Department of Psychiatry, University of Toronto, Toronto, ON, Canada. .,Violence Prevention Neurobiological Research Unit, CAMH, Toronto, ON, Canada. .,Waypoint Centre for Mental Health Care, Penetanguishene, ON, Canada. .,Waypoint/University of Toronto Research Chair in Forensic Mental Health Science, Penetanguishene, ON, Canada.
| | - Isabelle Boileau
- Centre for Addiction and Mental Health (CAMH), 250 College Street, Room 626, Toronto, ON, M5T 1R8, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - R Michael Bagby
- Centre for Addiction and Mental Health (CAMH), 250 College Street, Room 626, Toronto, ON, M5T 1R8, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada
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8
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Zanfirescu A, Nitulescu G, Mihai DP, Nitulescu GM. Identifying FAAH Inhibitors as New Therapeutic Options for the Treatment of Chronic Pain through Drug Repurposing. Pharmaceuticals (Basel) 2021; 15:38. [PMID: 35056095 PMCID: PMC8781999 DOI: 10.3390/ph15010038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/16/2021] [Accepted: 12/23/2021] [Indexed: 01/29/2023] Open
Abstract
Chronic pain determines a substantial burden on individuals, employers, healthcare systems, and society. Most of the affected patients report dissatisfaction with currently available treatments. There are only a few and poor therapeutic options-some therapeutic agents are an outgrowth of drugs targeting acute pain, while others have several serious side effects. One of the primary degradative enzymes for endocannabinoids, fatty acid amide hydrolase (FAAH) attracted attention as a significant molecular target for developing new therapies for neuropsychiatric and neurological diseases, including chronic pain. Using chemical graph mining, quantitative structure-activity relationship (QSAR) modeling, and molecular docking techniques we developed a multi-step screening protocol to identify repurposable drugs as FAAH inhibitors. After screening the DrugBank database using our protocol, 273 structures were selected, with five already approved drugs, montelukast, repaglinide, revefenacin, raloxifene, and buclizine emerging as the most promising repurposable agents for treating chronic pain. Molecular docking studies indicated that the selected compounds interact with the enzyme mostly non-covalently (except for revefenacin) through shape complementarity to the large substrate-binding pocket in the active site. A molecular dynamics simulation was employed for montelukast and revealed stable interactions with the enzyme. The biological activity of the selected compounds should be further confirmed by employing in vitro and in vivo studies.
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Affiliation(s)
- Anca Zanfirescu
- Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania
| | - Georgiana Nitulescu
- Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania
| | - Dragos Paul Mihai
- Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania
| | - George Mihai Nitulescu
- Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania
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Karimi SA, Kazemi F, Komaki H, Kourosh Arami M, Shahidi S, Komaki A. Electrophysiological study of the interactive role of the cannabinoid breakdown inhibitors and L-type calcium channels on granular neurons in the hippocampal dentate gyrus in rats. Neurol Res 2021; 44:446-454. [PMID: 34781846 DOI: 10.1080/01616412.2021.2004364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The interaction between L-type voltage-dependent Ca2+ channels and the endocannabinoid system (eCs) in synaptic plasticity is controversial. In the present research, the impact of acute administration of URB597, as an endocannabinoid breakdown inhibitor, was evaluated after chronic injection of verapamil, as a Ca2+ channels blocker, on inducing long-term potentiation (LTP) in the rat's hippocampal dentate gyrus (DG). Treatment of male Wistar rats was done using intraperitoneal(i.p) injection of verapamil hydrochloride (n = 8) and saline (n = 10), as the solvent of verapamil once a day within 13 days. Anesthetization was done by i.p injection of urethane and the rats were located in the stereotaxic apparatus for surgery, electrode implantation, and field potential recording. After observing a steady-state baseline response, saline or URB597 were injected (n = 9). Measurement of the population spike (PS) amplitude and slope of field excitatory postsynaptic potentials (fEPSPs) in the DG region was performed as a result of perforant pathway (PP) stimulation. Our treatments could inhibit LTP. Our results indicated that the chronic administration of verapamil produced a significant decrease in the slope of fEPSP and PS amplitude. Also, acute URB597 administration decreased the slope of fEPSP and PS amplitude compared to the saline group. Moreover, URB597 administration in combination with chronic administration of verapamil produced a greater decrease in fEPSP slope and PS amplitude than the saline group. These findings indicated that verapamil and URB597 disrupted LTP induction in the DG. Moreover, an interaction was observed between Ca2+ channels and eCs. Therefore, the eCs possibly play a selective role in synaptic plasticity.
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Affiliation(s)
- Seyed Asaad Karimi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.,Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Fatemeh Kazemi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Hamidreza Komaki
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Masoumeh Kourosh Arami
- Department of Basic Sciences, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Siamak Shahidi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.,Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Alireza Komaki
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.,Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
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10
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Elevated Brain Fatty Acid Amide Hydrolase Induces Depressive-Like Phenotypes in Rodent Models: A Review. Int J Mol Sci 2021; 22:ijms22031047. [PMID: 33494322 PMCID: PMC7864498 DOI: 10.3390/ijms22031047] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/15/2021] [Accepted: 01/18/2021] [Indexed: 12/17/2022] Open
Abstract
Altered activity of fatty acid amide hydrolase (FAAH), an enzyme of the endocannabinoid system, has been implicated in several neuropsychiatric disorders, including major depressive disorder (MDD). It is speculated that increased brain FAAH expression is correlated with increased depressive symptoms. The aim of this scoping review was to establish the role of FAAH expression in animal models of depression to determine the translational potential of targeting FAAH in clinical studies. A literature search employing multiple databases was performed; all original articles that assessed FAAH expression in animal models of depression were considered. Of the 216 articles that were screened for eligibility, 24 articles met inclusion criteria and were included in this review. Three key findings emerged: (1) FAAH expression is significantly increased in depressive-like phenotypes; (2) genetic knockout or pharmacological inhibition of FAAH effectively reduces depressive-like behavior, with a dose-dependent effect; and (3) differences in FAAH expression in depressive-like phenotypes were largely localized to animal prefrontal cortex, hippocampus and striatum. We conclude, based on the animal literature, that a positive relationship can be established between brain FAAH level and expression of depressive symptoms. In summary, we suggest that FAAH is a tractable target for developing novel pharmacotherapies for MDD.
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11
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N-docosahexaenoylethanolamine reduces neuroinflammation and cognitive impairment after mild traumatic brain injury in rats. Sci Rep 2021; 11:756. [PMID: 33436960 PMCID: PMC7804312 DOI: 10.1038/s41598-020-80818-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/28/2020] [Indexed: 12/14/2022] Open
Abstract
At present, there is a growing interest in the study of the neurotropic activity of polyunsaturated fatty acids ethanolamides (N-acylethanolamines). N-docosahexaenoylethanolamine (DHEA, synaptamide) is an endogenous metabolite and structural analogue of anandamide, a widely studied endocannabinoid derived from arachidonic acid. The results of this study demonstrate that DHEA, when administered subcutaneously (10 mg/kg/day, 7 days), promotes cognitive recovery in rats subjected to mild traumatic brain injury (mTBI). In the cerebral cortex of experimental animals, we analyzed the dynamics of Iba-1-positive microglia activity changes and the expression of pro-inflammatory markers (IL1β, IL6, CD86). We used immortalized mouse microglial cells (SIM-A9) to assess the effects of DHEA on LPS-induced cytokines/ROS/NO/nitrite, as well as on CD206 (anti-inflammatory microglia) and the antioxidant enzyme superoxide dismutase (SOD) production. In vivo and in vitro experiments showed that DHEA: (1) improves indicators of anxiety and long-term memory; (2) inhibits the pro-inflammatory microglial cells activity; (3) decrease the level of pro-inflammatory cytokines/ROS/NO/nitrites; (4) increase CD206 and SOD production. In general, the results of this study indicate that DHEA has a complex effect on the neuroinflammation processes, which indicates its high therapeutic potential.
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Ahmad H, Rauf K, Zada W, McCarthy M, Abbas G, Anwar F, Shah AJ. Kaempferol Facilitated Extinction Learning in Contextual Fear Conditioned Rats via Inhibition of Fatty-Acid Amide Hydrolase. Molecules 2020; 25:molecules25204683. [PMID: 33066366 PMCID: PMC7587337 DOI: 10.3390/molecules25204683] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/11/2020] [Accepted: 10/12/2020] [Indexed: 12/18/2022] Open
Abstract
Background: Fear, stress, and anxiety-like behaviors originate from traumatic events in life. Stress response is managed by endocannabinoids in the body by limiting the uncontrolled retrieval of aversive memories. Pharmacotherapy-modulating endocannabinoids, especially anandamide, presents a promising tool for treating anxiety disorders. Here, we investigated the effect of kaempferol, a flavonoid, in the extinction of fear related memories and associated anxiety-like behavior. Methods: The ability of kaempferol to inhibit fatty-acid amide hydrolase (FAAH, the enzyme that catabolizes anandamide) was assessed in vitro using an enzyme-linked immunosorbent assay (ELISA) kit. For animal studies (in vivo), the extinction learning was evaluated using contextual fear conditioning (CFC, a behavioral paradigm based on ability to learn and remember aversive stimuli). Furthermore, an elevated plus-maze (EPM) model was used for measuring anxiety-like behavior, while serum corticosterone served as a biochemical indicator of anxiety. Lastly, the interaction of kaempferol with FAAH enzyme was also assessed in silico (computational study). Results: Our data showed that kaempferol inhibited the FAAH enzyme with an IC50 value of 1 µM. In CFC, it reduced freezing behavior in rats. EPM data demonstrated anxiolytic activity as exhibited by enhanced number of entries and time spent in the open arm. No change in blood corticosterone levels was noted. Our computational study showed that Kaempferol interacted with the catalytic amino acids (SER241, PHE192, PHE381, and THR377) of FAAH enzyme Conclusion: Our study demonstrate that kaempferol facilitated the extinction of aversive memories along with a reduction of anxiety. The effect is mediated through the augmentation of endocannabinoids via the inhibition of FAAH enzyme.
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Affiliation(s)
- Hammad Ahmad
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, Khyber Pakhtunkhwa 22060, Pakistan; (H.A.); (K.R.); (W.Z.)
| | - Khalid Rauf
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, Khyber Pakhtunkhwa 22060, Pakistan; (H.A.); (K.R.); (W.Z.)
| | - Wahid Zada
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, Khyber Pakhtunkhwa 22060, Pakistan; (H.A.); (K.R.); (W.Z.)
| | - Margaret McCarthy
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Ghulam Abbas
- Department of Pharmacology, Faculty of Pharmacy, Ziauddin University, Karachi 75000, Pakistan;
| | - Fareeha Anwar
- Riphah Institute of Pharmaceutical Sciences, Riphah International University, Lahore Campus, Lahore 54000, Pakistan;
| | - Abdul Jabbar Shah
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, Khyber Pakhtunkhwa 22060, Pakistan; (H.A.); (K.R.); (W.Z.)
- Correspondence: ; Tel.: +(92)992-383591-6
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Low brain endocannabinoids associated with persistent non-goal directed nighttime hyperactivity after traumatic brain injury in mice. Sci Rep 2020; 10:14929. [PMID: 32913220 PMCID: PMC7483739 DOI: 10.1038/s41598-020-71879-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/13/2020] [Indexed: 02/06/2023] Open
Abstract
Traumatic brain injury (TBI) is a frequent cause of chronic headache, fatigue, insomnia, hyperactivity, memory deficits, irritability and posttraumatic stress disorder. Recent evidence suggests beneficial effects of pro-cannabinoid treatments. We assessed in mice levels of endocannabinoids in association with the occurrence and persistence of comparable sequelae after controlled cortical impact in mice using a set of long-term behavioral observations in IntelliCages, motor and nociception tests in two sequential cohorts of TBI/sham mice. TBI mice maintained lower body weights, and they had persistent low levels of brain ethanolamide endocannabinoids (eCBs: AEA, OEA, PEA) in perilesional and subcortical ipsilateral brain tissue (6 months), but rapidly recovered motor functions (within days), and average nociceptive responses were within normal limits, albeit with high variability, ranging from loss of thermal sensation to hypersensitivity. TBI mice showed persistent non-goal directed nighttime hyperactivity, i.e. they visited rewarding and non-rewarding operant corners with high frequency and random success. On successful visits, they made more licks than sham mice resulting in net over-licking. The lower the eCBs the stronger was the hyperactivity. In reward-based learning and reversal learning tasks, TBI mice were not inferior to sham mice, but avoidance memory was less stable. Hence, the major late behavioral TBI phenotype was non-goal directed nighttime hyperactivity and "over-licking" in association with low ipsilateral brain eCBs. The behavioral phenotype would agree with a "post-TBI hyperactivity disorder". The association with persistently low eCBs in perilesional and subcortical regions suggests that eCB deficiency contribute to the post-TBI psychopathology.
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Carnevali L, Statello R, Vacondio F, Ferlenghi F, Spadoni G, Rivara S, Mor M, Sgoifo A. Antidepressant-like effects of pharmacological inhibition of FAAH activity in socially isolated female rats. Eur Neuropsychopharmacol 2020; 32:77-87. [PMID: 31948828 DOI: 10.1016/j.euroneuro.2019.12.119] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/18/2019] [Accepted: 12/24/2019] [Indexed: 12/24/2022]
Abstract
Pharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid N-arachidonoylethanolamine (or anandamide, AEA), exerts favourable effects in rodent models of stress-related depression. Yet although depression seems to be more common among women than men and in spite of some evidence of sex differences in treatment efficacy, preclinical development of FAAH inhibitors for the pharmacotherapy of stress-related depression has been predominantly conducted in male animals. Here, adult female rats were exposed to six weeks of social isolation and, starting from the second week, treated with the FAAH inhibitor URB694 (0.3 mg/kg/day, i.p.) or vehicle. Compared to pair-housed females, socially isolated female rats treated with vehicle developed behavioral (mild anhedonia, passive stress coping) and physiological (reduced body weight gain, elevated plasma corticosterone levels) alterations. Moreover, prolonged social isolation provoked a reduction in brain-derived neurotrophic factor (BDNF) and AEA levels within the hippocampus. Together, these changes are indicative of an increased risk of developing a depressive-like state. Conversely, pharmacological inhibition of FAAH activity with URB694 restored both AEA and BDNF levels within the hippocampus of socially isolated rats and prevented the development of behavioral and physiological alterations. These results suggest a potential interplay between AEA-mediated signaling and hippocampal BDNF in the pathogenesis of depression-relevant behaviors and physiological alterations and antidepressant action of FAAH inhibition in socially isolated female rats.
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Affiliation(s)
- Luca Carnevali
- Stress Physiology Lab, Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
| | - Rosario Statello
- Stress Physiology Lab, Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | | | | | - Gilberto Spadoni
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Silvia Rivara
- Department of Food and Drug, University of Parma, Parma, Italy
| | - Marco Mor
- Department of Food and Drug, University of Parma, Parma, Italy
| | - Andrea Sgoifo
- Stress Physiology Lab, Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
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Kruk-Slomka M, Banaszkiewicz I, Slomka T, Biala G. Effects of Fatty Acid Amide Hydrolase Inhibitors Acute Administration on the Positive and Cognitive Symptoms of Schizophrenia in Mice. Mol Neurobiol 2019; 56:7251-7266. [PMID: 31004320 PMCID: PMC6815283 DOI: 10.1007/s12035-019-1596-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/02/2019] [Indexed: 12/31/2022]
Abstract
The connection between the endocannabinoid system (ECS) and schizophrenia is supported by a large body of research. The ECS is composed of two types cannabinoid (CB: CB1 and CB2) receptors and their endogenous ligands, endocannabinoids. The best-known endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are intracellularly degraded by fatty acid hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively. Thus, the function of ECS might be modulated in a direct way, through CB receptor ligands or indirectly by FAAH and MAGL inhibitors. We evaluated that the direct influence of ECS, using FAAH (URB 597) and MAGL (JZL 184) inhibitors, on the schizophrenia-like effects in mice. The behavioral schizophrenia-like symptoms were obtained in animals by using N-methyl D-aspartate (NMDA) receptor antagonists, MK-801. An acute administration of MK-801 (0.3 and 0.6 mg/kg) induced psychotic symptoms in rodents, manifested as the increase in locomotor activity, measured in actimeters, as well as the memory impairment, assessed in the passive avoidance (PA) task. We revealed that an acute administration of URB 597, at the dose of 0.3 mg/kg, attenuated MK-801 (0.6 mg/kg)-induced memory impairment. In turn, an acute administration of URB 597 at a higher dose (1 mg/kg) potentiated MK-801 (0.3 mg/kg)-induced memory impairment. Similarly, an acute administration of JZL 184 (20 and 40 mg/kg) intensified an amnestic effect of MK-801 (0.3 mg/kg). Moreover, an acute injection of JZL 184 (1 mg/kg) potentiated hyperlocomotion is provoked by MK-801 (0.3 and 0.6 mg/kg) administration. The present findings clearly indicate that ECS, through an indirect manner, modulates a variety of schizophrenia-like responses in mice.
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Affiliation(s)
- Marta Kruk-Slomka
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Chodzki 4a Street, 20-093, Lublin, Poland.
| | - Izabela Banaszkiewicz
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Chodzki 4a Street, 20-093, Lublin, Poland
| | - Tomasz Slomka
- Department of Mathematics and Medical Biostatistics, Medical University of Lublin, Jaczewskiego 4 Street, 20-954, Lublin, Poland
| | - Grazyna Biala
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Chodzki 4a Street, 20-093, Lublin, Poland
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Endocannabinoid interactions in the regulation of acquisition of contextual conditioned fear. Prog Neuropsychopharmacol Biol Psychiatry 2019; 90:84-91. [PMID: 30458201 DOI: 10.1016/j.pnpbp.2018.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 11/23/2022]
Abstract
Endocannabinoids (eCBs) anandamide (AEA) and 2-arachidonoylglycerol (2-AG) were shown to be involved in the basis of trauma-induced behavioral changes, particularly contextual conditioned fear, however, their ligand-specific effects and possible interactions are poorly understood. Here we assessed specific eCB effects and interactions on acquisition of contextual conditioned fear employing electric footshocks in a rat model. We selectively increased eCB levels by pharmacological blockade of the degrading enzymes of AEA by URB597 and 2-AG by JZL184 before traumatization either systemically or locally in relevant brain areas, the prelimbic cortex (PrL), ventral hippocampus (vHC) and basolateral amygdala (BLA). Following traumatization, a series of contextual reminders were conducted during which conditioned fear was assessed. While systemic URB597-treatment during traumatization only slightly enhanced the acquisition of contextual conditioned fear, administration of the compound in the PrL and vHC led to the acquisition of stable, lasting conditioned fear, resistant to extinction. These effects of URB597 were blocked by simultaneous administration of JZL184. Similar treatment effects did not occur in the BLA. Treatment effects were not secondary to alterations in locomotor activity or nociception. Our findings suggest that AEA and 2-AG functionally interact in the regulation of acquisition of contextual conditioned fear. AEA signaling in the PrL and vHC is a crucial promoter of fear acquisition while 2-AG potentially modulates this effect. The lack of eCB effects in the BLA suggests functional specificity of eCBs at distinct brain sites.
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Role of endocannabinoids in the hippocampus and amygdala in emotional memory and plasticity. Neuropsychopharmacology 2018; 43:2017-2027. [PMID: 29977073 PMCID: PMC6098035 DOI: 10.1038/s41386-018-0135-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 12/13/2022]
Abstract
Posttraumatic stress disorder (PTSD) is characterized by the reexperiencing of a traumatic event and is associated with slower extinction of fear responses. Impaired extinction of fearful associations to trauma-related cues may interfere with treatment response, and extinction deficits may be premorbid risk factors for the development of PTSD. We examined the effects of exposure to a severe footshock followed by situational reminders (SRs) on extinction, plasticity, and endocannabinoid (eCB) content and activity in the hippocampal CA1 area and basolateral amygdala (BLA). We also examined whether enhancing eCB signaling before extinction, using the fatty acid amide hydrolase (FAAH) inhibitor URB597, could prevent the shock/SRs-induced effects on fear response and plasticity. URB597 administered systemically (0.3 mg/kg) or locally into the CA1 or BLA (0.1 µg/side) prior to extinction decreased fear retrieval and this effect persisted throughout extinction training and did not recuperate during spontaneous recovery. A low dose of the CB1 receptor antagonist AM251 (0.3 mg/kg i.p. or 0.01 µg/0.5 µl intra-CA1 or intra-BLA) blocked these effects suggesting that the effects of URB597 were CB1 receptor-dependent. Exposure to shock and reminders induced behavioral metaplasticity with opposite effects on long-term potentiation (LTP) in the hippocampus (impairment) and the BLA (enhancement). URB597 was found to prevent the opposite shock/SR-induced metaplasticity in hippocampal and BLA-LTP. Exposure to shock and reminders might cause variation in endogenous cannabinoid levels that could affect fear-circuit function. Indeed, exposure to shock and SRs affected eCB content: increased 2-arachidonoyl-glycerol (2-AG) and N-arachidonylethanolamine (AEA) levels in the CA1, decreased serum and BLA AEA levels while shock exposure increased FAAH activity in the CA1 and BLA. FAAH inhibition before extinction abolished fear and modulated LTP in the hippocampus and amygdala, brain regions pertinent to emotional memory. The findings suggest that targeting the eCB system before extinction may be beneficial in fear memory attenuation and these effects may involve metaplasticity in the CA1 and BLA.
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Integrating Endocannabinoid Signaling and Cannabinoids into the Biology and Treatment of Posttraumatic Stress Disorder. Neuropsychopharmacology 2018; 43:80-102. [PMID: 28745306 PMCID: PMC5719095 DOI: 10.1038/npp.2017.162] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/17/2017] [Accepted: 07/20/2017] [Indexed: 01/21/2023]
Abstract
Exposure to stress is an undeniable, but in most cases surmountable, part of life. However, in certain individuals, exposure to severe or cumulative stressors can lead to an array of pathological conditions including posttraumatic stress disorder (PTSD), characterized by debilitating trauma-related intrusive thoughts, avoidance behaviors, hyperarousal, as well as depressed mood and anxiety. In the context of the rapidly changing political and legal landscape surrounding use of cannabis products in the USA, there has been a surge of public and research interest in the role of cannabinoids in the regulation of stress-related biological processes and in their potential therapeutic application for stress-related psychopathology. Here we review the current state of knowledge regarding the effects of cannabis and cannabinoids in PTSD and the preclinical and clinical literature on the effects of cannabinoids and endogenous cannabinoid signaling systems in the regulation of biological processes related to the pathogenesis of PTSD. Potential therapeutic implications of the reviewed literature are also discussed. Finally, we propose that a state of endocannabinoid deficiency could represent a stress susceptibility endophenotype predisposing to the development of trauma-related psychopathology and provide biologically plausible support for the self-medication hypotheses used to explain high rates of cannabis use in patients with trauma-related disorders.
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Effect of footshock stress on place conditioning produced by Δ 9-tetrahydrocannabinol and the fatty acid amide hydrolase (FAAH) inhibitor, URB597, in Sprague-Dawley rats. Psychopharmacology (Berl) 2017; 234:3229-3240. [PMID: 28803323 DOI: 10.1007/s00213-017-4714-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Accepted: 08/06/2017] [Indexed: 10/19/2022]
Abstract
RATIONALE Unlike other drugs of abuse, Δ9-tetrahydrocanabinol (THC) is generally aversive in rodent conditioned place preference models, but little is known about how stress may modify THC affective properties. OBJECTIVE We evaluate the potential of footshock stress to enhance the rewarding effects of THC and the fatty acid amide hydrolase inhibitor, URB597, as it has been shown to enhance their anxiolytic effects. MATERIALS AND METHODS The effect of footshock stress 24 h prior to each conditioning trial on the rewarding/aversive effects of THC (1, 0.1, 0.5 mg/kg, ip) and URB597 (0.3 mg/kg, ip) was evaluated in an unbiased place conditioning procedure in rats. Subsequently, the same stressor was given immediately prior to conditioning with THC (1 and 0.1 mg/kg). Locomotor activity was also measured during conditioning. RESULTS A dose of 1 mg/kg THC, but not 0.1-0.5 mg/kg, produced a conditioned place aversion (CPA) that was not modified by footshock delivered 24 h prior to conditioning trials; however, footshock delivered immediately prior to conditioning trials prevented that CPA. Lower doses of THC and URB597 produced no place conditioning regardless of footshock conditions. A dose of 1 mg/kg THC produced locomotor suppression during conditioning trials that was prevented by footshock delivered 24 h before and reversed to locomotor activation by footshock delivered immediately before conditioning. CONCLUSIONS Unlike the effect of footshock on THC- and URB597-induced anxiolytic effects, footshock does not promote THC or URB597-induced reward in a conditioned place preference paradigm. However, footshock stress reverses the sedative effects of 1 mg/kg THC.
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Natividad LA, Buczynski MW, Herman MA, Kirson D, Oleata CS, Irimia C, Polis I, Ciccocioppo R, Roberto M, Parsons LH. Constitutive Increases in Amygdalar Corticotropin-Releasing Factor and Fatty Acid Amide Hydrolase Drive an Anxious Phenotype. Biol Psychiatry 2017; 82:500-510. [PMID: 28209423 PMCID: PMC5509512 DOI: 10.1016/j.biopsych.2017.01.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/21/2016] [Accepted: 01/04/2017] [Indexed: 01/15/2023]
Abstract
BACKGROUND Corticotropin-releasing factor (CRF) mediates anxiogenic responses by activating CRF type 1 (CRF1) receptors in limbic brain regions. Anxiety is further modulated by the endogenous cannabinoid (eCB) system that attenuates the synaptic effects of stress. In the amygdala, acute stress activates the enzymatic clearance of the eCB N-arachidonoylethanolamine via fatty acid amide hydrolase (FAAH), although it is unclear whether chronic dysregulation of CRF systems induces maladaptive changes in amygdalar eCB signaling. Here, we used genetically selected Marchigian Sardinian P (msP) rats carrying an innate overexpression of CRF1 receptors to study the role of constitutive upregulation in CRF systems on amygdalar eCB function and persistent anxiety-like effects. METHODS We applied behavioral, pharmacological, and biochemical methods to broadly characterize anxiety-like behaviors and amygdalar eCB clearance enzymes in msP versus nonselected Wistar rats. Subsequent studies examined the influence of dysregulated CRF and FAAH systems in altering excitatory transmission in the central amygdala (CeA). RESULTS msPs display an anxious phenotype accompanied by elevations in amygdalar FAAH activity and reduced dialysate N-arachidonoylethanolamine levels in the CeA. Elevations in CRF-CRF1 signaling dysregulate FAAH activity, and this genotypic difference is normalized with pharmacological blockade of CRF1 receptors. msPs also exhibit elevated baseline glutamatergic transmission in the CeA, and dysregulated CRF-FAAH facilitates stress-induced increases in glutamatergic activity. Treatment with an FAAH inhibitor relieves sensitized glutamatergic responses in msPs and attenuates the anxiety-like phenotype. CONCLUSIONS Pathological anxiety and stress hypersensitivity are driven by constitutive increases in CRF1 signaling that dysregulate N-arachidonoylethanolamine signaling mechanisms and reduce neuronal inhibitory control of CeA glutamatergic synapses.
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Affiliation(s)
- Luis A Natividad
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
| | - Matthew W Buczynski
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California; Virginia Tech School of Neuroscience, Virginia Tech, Blacksburg, Virginia
| | - Melissa A Herman
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
| | - Dean Kirson
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
| | - Christopher S Oleata
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
| | - Cristina Irimia
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
| | - Ilham Polis
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
| | - Roberto Ciccocioppo
- School of Pharmacy, Pharmacology Unit, University of Camerino, Camerino, Italy
| | - Marisa Roberto
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California.
| | - Loren H Parsons
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California
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Carnevali L, Rivara S, Nalivaiko E, Thayer JF, Vacondio F, Mor M, Sgoifo A. Pharmacological inhibition of FAAH activity in rodents: A promising pharmacological approach for psychological—cardiac comorbidity? Neurosci Biobehav Rev 2017; 74:444-452. [DOI: 10.1016/j.neubiorev.2016.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/19/2016] [Accepted: 04/20/2016] [Indexed: 01/09/2023]
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Panlilio LV, Thorndike EB, Nikas SP, Alapafuja SO, Bandiera T, Cravatt BF, Makriyannis A, Piomelli D, Goldberg SR, Justinova Z. Effects of fatty acid amide hydrolase (FAAH) inhibitors on working memory in rats. Psychopharmacology (Berl) 2016; 233:1879-88. [PMID: 26558620 PMCID: PMC4846548 DOI: 10.1007/s00213-015-4140-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 10/29/2015] [Indexed: 11/24/2022]
Abstract
RATIONALE Manipulations of the endocannabinoid system could potentially produce therapeutic effects with minimal risk of adverse cannabis-like side effects. Inhibitors of fatty acid amide hydrolase (FAAH) increase endogenous levels of the cannabinoid-receptor agonist, anandamide, and show promise for treating a wide range of disorders. However, their effects on learning and memory have not been fully characterized. OBJECTIVES We determined the effects of five structurally different FAAH inhibitors in an animal model of working memory known to be sensitive to impairment by delta-9 tetrahydrocannabinol (THC). METHODS A delayed nonmatching-to-position procedure was used in rats. Illuminated nosepoke holes were used to provide sample cues (left versus right) and record responses (correct versus incorrect) after delays ranging from 0 to 28 s. Various test drugs were given acutely up to two times per week before daily sessions. RESULTS One FAAH inhibitor, AM3506 (3 mg/kg), decreased accuracy in the memory task. Four other FAAH inhibitors (URB597, URB694, PF-04457845, and ARN14633) and a monoacylglycerol lipase inhibitor (JZL184, which blocks the degradation of the endocannabinoid 2-arachidonoylglycerol) had no effect. Testing of AM3506 in combination with antagonists for receptors known to be affected by anandamide and other fatty acid amides indicated that the impairment induced by AM3506 was mediated by cannabinoid CB1 receptors, and not by alpha-type peroxisome proliferator-activated receptors (PPAR-alpha) or vanilloid transient receptor potential cation channels (TRPV1). CONCLUSIONS FAAH inhibitors differ with respect to their potential for memory impairment, abuse liability, and probably other cannabis-like effects, and they should be evaluated individually for specific therapeutic and adverse effects.
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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, Baltimore, MD, 21224, USA
| | - Eric B. Thorndike
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Spyros P. Nikas
- Center for Drug Discovery and Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | | | - Tiziano Bandiera
- Drug Discovery and Development, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Benjamin F. Cravatt
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, USA; Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Alexandros Makriyannis
- Center for Drug Discovery, Department of Pharmaceutical Sciences and Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA
| | - Daniele Piomelli
- Drug Discovery and Development, Istituto Italiano di Tecnologia, Genoa, Italy; Department of Anatomy and Neurobiology, University of California Irvine, Irvine, California, USA
| | - Steven R. Goldberg
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Zuzana Justinova
- 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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Aliczki M, Barna I, Till I, Baranyi M, Sperlagh B, Goldberg SR, Haller J. The effects anandamide signaling in the prelimbic cortex and basolateral amygdala on coping with environmental stimuli in rats. Psychopharmacology (Berl) 2016; 233:1889-99. [PMID: 26809457 DOI: 10.1007/s00213-016-4219-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/18/2016] [Indexed: 01/25/2023]
Abstract
RATIONALE Several lines of recent evidence suggest that endocannabinoids affect behavior by influencing the general patterns of challenge responding. OBJECTIVES Here, we investigated the brain mechanisms underlying this phenomenon in rats. METHODS The anandamide hydrolysis inhibitor URB597 was condensed into the tip of stainless steel cannulae, which were chronically implanted slightly above the prelimbic cortex (PRL) or the basolateral amygdala (BLA), two important regions of coping and endocannabinoid action. Thereafter, we investigated behavioral responsiveness to ambient light level in the elevated plus-maze and conditioned fear tests. RESULTS URB597 concentration was ~30 μg/mg protein in target areas; local brain anandamide levels increased threefold, without significant changes in 2-arachidonoylglycerol. High levels of illumination halved the time spent by controls in the open arms of the plus-maze. No similar decrease was observed in rats with URB597 implants in the PRL. High light decreased conditioned fear by 30 % in controls, but not in rats with prelimbic URB597 implants. Unresponsiveness to environmental challenges was not attributable to the anxiolytic effects of anandamide enhancement, as implants induced paradoxical anxiogenic-like effects under low light, which could be explained by effects on stimulus responsiveness rather than by effects on anxiety. URB597 implants targeting the BLA did not affect stimulus responsiveness. CONCLUSIONS Our findings show that elevated prelimbic anandamide signaling leads to less environment-dependent (more autonomous) behavioral responses to challenges, which is an attribute of active coping styles. These findings are discussed in light of two emerging concepts of endocannabinoid roles, particularly "emotional homeostasis" and "active coping."
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Affiliation(s)
- Mano Aliczki
- Department of Behavioural Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 1450, Budapest, P.O. Box 67, Hungary
| | - Istvan Barna
- Department of Behavioural Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 1450, Budapest, P.O. Box 67, Hungary
| | - Ibolya Till
- Department of Behavioural Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 1450, Budapest, P.O. Box 67, Hungary
| | - Maria Baranyi
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Beata Sperlagh
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Steven R Goldberg
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Jozsef Haller
- Department of Behavioural Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 1450, Budapest, P.O. Box 67, Hungary.
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Morena M, Patel S, Bains JS, Hill MN. Neurobiological Interactions Between Stress and the Endocannabinoid System. Neuropsychopharmacology 2016; 41:80-102. [PMID: 26068727 PMCID: PMC4677118 DOI: 10.1038/npp.2015.166] [Citation(s) in RCA: 396] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/20/2015] [Accepted: 05/20/2015] [Indexed: 12/18/2022]
Abstract
Stress affects a constellation of physiological systems in the body and evokes a rapid shift in many neurobehavioral processes. A growing body of work indicates that the endocannabinoid (eCB) system is an integral regulator of the stress response. In the current review, we discuss the evidence to date that demonstrates stress-induced regulation of eCB signaling and the consequential role changes in eCB signaling have with respect to many of the effects of stress. Across a wide array of stress paradigms, studies have generally shown that stress evokes bidirectional changes in the two eCB molecules, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG), with stress exposure reducing AEA levels and increasing 2-AG levels. Additionally, in almost every brain region examined, exposure to chronic stress reliably causes a downregulation or loss of cannabinoid type 1 (CB1) receptors. With respect to the functional role of changes in eCB signaling during stress, studies have demonstrated that the decline in AEA appears to contribute to the manifestation of the stress response, including activation of the hypothalamic-pituitary-adrenal (HPA) axis and increases in anxiety behavior, while the increased 2-AG signaling contributes to termination and adaptation of the HPA axis, as well as potentially contributing to changes in pain perception, memory and synaptic plasticity. More so, translational studies have shown that eCB signaling in humans regulates many of the same domains and appears to be a critical component of stress regulation, and impairments in this system may be involved in the vulnerability to stress-related psychiatric conditions, such as depression and posttraumatic stress disorder. Collectively, these data create a compelling argument that eCB signaling is an important regulatory system in the brain that largely functions to buffer against many of the effects of stress and that dynamic changes in this system contribute to different aspects of the stress response.
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Affiliation(s)
- Maria Morena
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada,Mathison Centre for Mental Health Research and Education, University of Calgary, Calgary, AB, Canada
| | - Sachin Patel
- Department of Molecular Physiology and Biophysics and Psychiatry, Vanderbilt Brain Institute, Vanderbilt-Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jaideep S Bains
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada,Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Matthew N Hill
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada,Mathison Centre for Mental Health Research and Education, University of Calgary, Calgary, AB, Canada,Departments of Cell Biology and Anatomy and Psychiatry, University of Calgary, Calgary, AB, Canada,Departments of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N4N1, Canada, Tel: +1 403 220 8466, Fax: +1 403 283 2700, E-mail:
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25
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Abstract
Corticotropin-releasing hormone (CRH) is a central integrator in the brain of endocrine and behavioral stress responses, whereas activation of the endocannabinoid CB1 receptor suppresses these responses. Although these systems regulate overlapping functions, few studies have investigated whether these systems interact. Here we demonstrate a novel mechanism of CRH-induced anxiety that relies on modulation of endocannabinoids. Specifically, we found that CRH, through activation of the CRH receptor type 1 (CRHR1), evokes a rapid induction of the enzyme fatty acid amide hydrolase (FAAH), which causes a reduction in the endocannabinoid anandamide (AEA), within the amygdala. Similarly, the ability of acute stress to modulate amygdala FAAH and AEA in both rats and mice is also mediated through CRHR1 activation. This interaction occurs specifically in amygdala pyramidal neurons and represents a novel mechanism of endocannabinoid-CRH interactions in regulating amygdala output. Functionally, we found that CRH signaling in the amygdala promotes an anxious phenotype that is prevented by FAAH inhibition. Together, this work suggests that rapid reductions in amygdala AEA signaling following stress may prime the amygdala and facilitate the generation of downstream stress-linked behaviors. Given that endocannabinoid signaling is thought to exert "tonic" regulation on stress and anxiety responses, these data suggest that CRH signaling coordinates a disruption of tonic AEA activity to promote a state of anxiety, which in turn may represent an endogenous mechanism by which stress enhances anxiety. These data suggest that FAAH inhibitors may represent a novel class of anxiolytics that specifically target stress-induced anxiety.
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Batista LA, Bastos JR, Moreira FA. Role of endocannabinoid signalling in the dorsolateral periaqueductal grey in the modulation of distinct panic-like responses. J Psychopharmacol 2015; 29:335-43. [PMID: 25601395 DOI: 10.1177/0269881114566259] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Panic attacks, a major feature of panic disorder, can be modelled in rats by exposing animals to stimuli that induce escape reactions, such as the elevated T-maze or the activation of the dorsolateral periaqueductal grey. Since the cannabinoid CB1 receptor modulates various types of aversive responses, this study tested the hypothesis that enhancement of endocannabinoid signalling in the dorsolateral periaqueductal grey inhibits panic-like reactions in rats. Local injection of the CB1 agonist, arachidonoyl 2-Chloroethylamide (0.005-0.5 pmol), attenuated the escape response from the open arm of the elevated T-maze, a panicolytic effect. The anandamide hydrolysis inhibitor, URB597 (0.3-3 nmol), did not induce consistent results. In the test of dorsolateral periaqueductal grey stimulation with d,l-homocysteic acid, arachidonoyl 2-Chloroethylamide, at the lowest dose, attenuated the escape reaction. The highest dose of URB597 also inhibited this response, contrary to the result obtained in the elevated T-maze. This effect was reversed by the CB1 antagonist, AM251 (100 pmol). The present results confirm the anti-aversive property of direct CB1 receptor activation in the dorsolateral periaqueductal grey. The effect of the anandamide hydrolysis inhibitor, however, could be detected only in a model employing direct stimulation of this structure. Altogether, these results suggest that anandamide signalling is recruited only under certain types of aversive stimuli.
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Affiliation(s)
- Luara A Batista
- Graduate School in Neuroscience, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Brazil
| | - Juliana R Bastos
- Graduate School in Neuroscience, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Brazil
| | - Fabricio A Moreira
- Department of Pharmacology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Brazil
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27
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Haller J, Aliczki M, Pelczer KG, Spitzer K, Balogh Z, Kantor S. Effects of the fatty acid amide hydrolase inhibitor URB597 on coping behavior under challenging conditions in mice. Psychopharmacology (Berl) 2014; 231:593-601. [PMID: 24037493 DOI: 10.1007/s00213-013-3273-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 08/27/2013] [Indexed: 12/15/2022]
Abstract
RATIONALE Recent evidence suggests that in addition to controlling emotional behavior in general, endocannabinoid signaling is engaged in shaping behavioral responses to challenges. This important function of endocannabinoids is still poorly understood. OBJECTIVES Here we investigated the impact of blockade of fatty acid amide hydrolase (FAAH), the degrading enzyme of anandamide on behavioral responses induced by challenges of different intensity. METHODS Mice treated with FAAH inhibitor URB597 were either manually restrained on their backs (back test) or received foot-shocks. RESULTS The behavior of mice showed bimodal distribution in the back test: they either predominantly showed escape attempts or equally distributed time between passivity and escape. URB597 increased escapes in animals with low escape scores. No effects were noticed in mice showing high escape scores, which is likely due to a ceiling effect. We hypothesized that stronger stressors would wash out individual differences in coping; therefore, we exposed mice to foot-shocks that decreased locomotion and increased freezing in all mice. URB597 ameliorated both responses. The re-exposure of mice to the shock cage 14 days later without delivering shocks or treatment was followed by reduced and fragmented sleep as shown by electrophysiological recordings. Surprisingly, sleep was more disturbed after the reminder than after shocks in rats receiving vehicle before foot-shocks. These reminder-induced disturbances were abolished by URB597 administered before shocks. CONCLUSIONS These findings suggest that FAAH blockade has an important role in the selection of behavioral responses under challenging conditions and-judging from its long-term effects-that it influences the cognitive appraisal of the challenge.
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Affiliation(s)
- Jozsef Haller
- Department of Behavioural Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O. Box 67, 1450, Budapest, Hungary,
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