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Zhu L, Zheng D, Li R, Shen CJ, Cai R, Lyu C, Tang B, Sun H, Wang X, Ding Y, Xu B, Jia G, Li X, Gao L, Li XM. Induction of Anxiety-Like Phenotypes by Knockdown of Cannabinoid Type-1 Receptors in the Amygdala of Marmosets. Neurosci Bull 2023; 39:1669-1682. [PMID: 37368194 PMCID: PMC10603018 DOI: 10.1007/s12264-023-01081-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 03/08/2023] [Indexed: 06/28/2023] Open
Abstract
The amygdala is an important hub for regulating emotions and is involved in the pathophysiology of many mental diseases, such as depression and anxiety. Meanwhile, the endocannabinoid system plays a crucial role in regulating emotions and mainly functions through the cannabinoid type-1 receptor (CB1R), which is strongly expressed in the amygdala of non-human primates (NHPs). However, it remains largely unknown how the CB1Rs in the amygdala of NHPs regulate mental diseases. Here, we investigated the role of CB1R by knocking down the cannabinoid receptor 1 (CNR1) gene encoding CB1R in the amygdala of adult marmosets through regional delivery of AAV-SaCas9-gRNA. We found that CB1R knockdown in the amygdala induced anxiety-like behaviors, including disrupted night sleep, agitated psychomotor activity in new environments, and reduced social desire. Moreover, marmosets with CB1R-knockdown had up-regulated plasma cortisol levels. These results indicate that the knockdown of CB1Rs in the amygdala induces anxiety-like behaviors in marmosets, and this may be the mechanism underlying the regulation of anxiety by CB1Rs in the amygdala of NHPs.
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Affiliation(s)
- Lin Zhu
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Di Zheng
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Rui Li
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Chen-Jie Shen
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Ruolan Cai
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Chenfei Lyu
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Binliang Tang
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
- Rehabilitation Medicine Center, Rehabilitation & Sports Medicine Research Institute of Zhejiang Province, Department of Rehabilitation Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, 311399, China
| | - Hao Sun
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Xiaohui Wang
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Yu Ding
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Bin Xu
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Guoqiang Jia
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Xinjian Li
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China
| | - Lixia Gao
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China.
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, 310029, China.
| | - Xiao-Ming Li
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brian Medicine, Zhejiang University, Hangzhou, 310058, China.
- Center for Brain Science and Brain-Inspired Intelligence, Research Units for Emotion and Emotion Disorders, Chinese Academy of Medical Sciences, China/Guangdong-Hong Kong-Macao Greater Bay Area, Joint Institute for Genetics and Genome Medicine Between Zhejiang University and University of Toronto, Hangzhou, 310058, China.
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Pereira V, Arias JA, Llebaria A, Goudet C. Photopharmacological manipulation of amygdala metabotropic glutamate receptor mGlu4 alleviates neuropathic pain. Pharmacol Res 2023; 187:106602. [PMID: 36529205 DOI: 10.1016/j.phrs.2022.106602] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022]
Abstract
Neuropathic pain is a common health problem resulting in exacerbated response to noxious and non noxious stimuli, as well as impaired emotional and cognitive responses. Unfortunately, neuropathic pain is also one of the most difficult pain syndromes to manage, highlighting the importance of better understanding the brain regions and neuromodulatory mechanisms involved in its regulation. Among the many interconnected brain areas which process pain, the amygdala is known to play an important role in the integration of sensory and emotional pain signals. Here we questioned the ability of a recently identified neuromodulatory mechanism associated with the metabotropic glutamate receptors mGlu4 in the amygdala to modulate neuropathic pain. In a murine model of peripheral mononeuropathy, we demonstrate that pharmacological activation of amygdala mGlu4 efficiently alleviates sensory and depressive-like symptoms in both male and female mice. Moreover, we reveal a differential modulation of these symptoms. Activating mGlu4 in the contralateral amygdala relative to the side of the mononeuropathy, is necessary and sufficient to relieve both sensory and depressive-like symptoms, while ipsilateral activation solely reduces depressive-like symptoms. Furthermore, using photopharmacology, a recent strategy allowing precise photocontrol of endogenous proteins, we further demonstrate the dynamic alleviation of neuropathic pain through light-dependent facilitation of mGlu4 by a photoswitchable positive allosteric modulator. Finally, coupling photopharmacology and analgesic conditioned place preference, we show a significant pain-reducing effect of mGlu4 activation. Taken together, these data highlight the analgesic potential of enhancing amygdala mGlu4 activity to counteract neuropathy reinforcing its therapeutic interest for the treatment of pathological pain.
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Affiliation(s)
| | | | - Amadeu Llebaria
- MCS, Laboratory of Medicinal Chemistry & Synthesis, Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Cyril Goudet
- IGF, Univ. Montpellier, CNRS, INSERM, Montpellier, France.
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Green DGJ, Westwood DJ, Kim J, Best LM, Kish SJ, Tyndale RF, McCluskey T, Lobaugh NJ, Boileau I. Fatty acid amide hydrolase levels in brain linked with threat-related amygdala activation. NEUROIMAGE. REPORTS 2022; 2:100094. [PMID: 37235067 PMCID: PMC10206405 DOI: 10.1016/j.ynirp.2022.100094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/08/2022] [Accepted: 04/13/2022] [Indexed: 05/28/2023]
Abstract
Background Preclinical evidence suggests that increasing levels of the major endocannabinoid anandamide decreases anxiety and fear responses potentially through its effects in the amygdala. Here we used neuroimaging to test the hypothesis that lower fatty acid amide hydrolase (FAAH), the main catabolic enzyme for anandamide, is associated with a blunted amygdala response to threat. Methods Twenty-eight healthy participants completed a positron emission tomography (PET) scan with the radiotracer for FAAH, [11C]CURB, as well as a block-design functional magnetic resonance imaging session during which angry and fearful faces meant to activate the amygdala were presented. Results [11C]CURB binding in the amygdala as well as in the medial prefrontal cortex, cingulate and hippocampus correlated positively with blood-oxygen-level-dependent (BOLD) signal during processing of angry and fearful faces (pFWE < 0.05). Conclusion Our finding that lower levels of FAAH in amygdala, medial prefrontal cortex, cingulate and hippocampus was associated with a dampened amygdala response to a threatening social cue aligns with preclinical and neuroimaging studies in humans and suggests the involvement of FAAH in modulating stress and anxiety in humans. The current neuroimaging study also lends support for the potential use of FAAH inhibitors to control amygdala hyperactivity, which is known to be involved in the pathophysiology of anxiety and trauma-related disorders.
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Affiliation(s)
- Duncan GJ. Green
- Addiction Imaging Research Group, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | | | - Jinhee Kim
- Departments of Psychiatry, Canada
- Department of Psychology, Korea University, Republic of Korea
| | - Laura M. Best
- Addiction Imaging Research Group, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Stephen J. Kish
- Human Brain Lab, Canada
- Campbell Family Mental Health Research Institute, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada
- Departments of Psychiatry, Canada
- Pharmacology & Toxicology, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Rachel F. Tyndale
- Campbell Family Mental Health Research Institute, Canada
- Departments of Psychiatry, Canada
- Pharmacology & Toxicology, Canada
| | - Tina McCluskey
- Human Brain Lab, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada
| | - Nancy J. Lobaugh
- Campbell Family Mental Health Research Institute, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Isabelle Boileau
- Addiction Imaging Research Group, Canada
- Campbell Family Mental Health Research Institute, Canada
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada
- Departments of Psychiatry, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
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Effects of Intra-BLA Administration of PPAR Antagonists on Formalin-Evoked Nociceptive Behaviour, Fear-Conditioned Analgesia, and Conditioned Fear in the Presence or Absence of Nociceptive Tone in Rats. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27062021. [PMID: 35335382 PMCID: PMC8949000 DOI: 10.3390/molecules27062021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 11/16/2022]
Abstract
There is evidence for the involvement of peroxisome proliferator-activated receptors (PPARs) in pain, cognition, and anxiety. However, their role in pain–fear interactions is unknown. The amygdala plays a key role in pain, conditioned fear, and fear-conditioned analgesia (FCA). We investigated the effects of intra-basolateral amygdala (BLA) administration of PPARα, PPARβ/δ, and PPARγ antagonists on nociceptive behaviour, FCA, and conditioned fear in the presence or absence of nociceptive tone. Male Sprague-Dawley (SD) rats received footshock (FC) or no footshock (NFC) in a conditioning arena. Twenty-three and a half hours later, rats received an intraplantar injection of formalin or saline and, 15 min later, intra-BLA microinjections of vehicle, PPARα (GW6471) PPARβ/δ (GSK0660), or PPARγ (GW9662) antagonists before arena re-exposure. Pain and fear-related behaviour were assessed, and neurotransmitters/endocannabinoids measured post-mortem. Intra-BLA administration of PPARα or PPARγ antagonists potentiated freezing in the presence of nociceptive tone. Blockade of all PPAR subtypes in the BLA increased freezing and BLA dopamine levels in NFC rats in the absence of nociceptive tone. Administration of intra-BLA PPARα and PPARγ antagonists increased levels of dopamine in the BLA compared with the vehicle-treated counterparts. In conclusion, PPARα and PPARγ in the BLA play a role in the expression or extinction of conditioned fear in the presence or absence of nociceptive tone.
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Warren WG, Papagianni EP, Stevenson CW, Stubbendorff C. In it together? The case for endocannabinoid-noradrenergic interactions in fear extinction. Eur J Neurosci 2021; 55:952-970. [PMID: 33759226 DOI: 10.1111/ejn.15200] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/26/2021] [Accepted: 03/17/2021] [Indexed: 12/18/2022]
Abstract
Anxiety and trauma-related disorders, such as post-traumatic stress disorder (PTSD), are debilitating mental illnesses with great personal and socioeconomic costs. Examining memory formation and relevant behavioural responding associated with aversive stimuli may improve our understanding of the neurobiology underlying fear memory processing and PTSD treatment. The neurocircuitry underpinning learned fear and its inhibition through extinction is complex, involving synergistic interactions between different neurotransmitter systems in inter-connected brain areas. Endocannabinoid and noradrenergic transmission have both been implicated separately in fear memory processing and PTSD, but potential interactions between these systems in relation to fear extinction have received little attention to date. Their receptors are expressed together in brain areas crucial for fear extinction, which is enhanced by both cannabinoid and noradrenergic receptor activation in these areas. Moreover, cannabinoid signalling modulates the activity of locus coeruleus noradrenaline (NA) neurons and the release of NA in the medial prefrontal cortex, a brain area that is crucial for fear extinction. Interestingly, endocannabinoid-noradrenergic system interactions have been shown to regulate the encoding and retrieval of fear memory. Thus, noradrenergic regulation of fear extinction may also be driven indirectly in part via cannabinoid receptor signalling. In this perspective paper, we collate the available relevant literature and propose a synergistic role for the endocannabinoid and noradrenergic systems in regulating fear extinction, the study of which may further our understanding of the neurobiological substrates of PTSD and its treatment.
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Affiliation(s)
- William G Warren
- School of Biosciences, University of Nottingham, Loughborough, UK
| | | | - Carl W Stevenson
- School of Biosciences, University of Nottingham, Loughborough, UK
| | - Christine Stubbendorff
- School of Biosciences, University of Nottingham, Loughborough, UK.,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
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Gunduz-Cinar O. The endocannabinoid system in the amygdala and modulation of fear. Prog Neuropsychopharmacol Biol Psychiatry 2021; 105:110116. [PMID: 32976951 PMCID: PMC7511205 DOI: 10.1016/j.pnpbp.2020.110116] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/07/2020] [Accepted: 09/20/2020] [Indexed: 01/01/2023]
Abstract
Posttraumatic stress disorder (PTSD) is a persistent, trauma induced psychiatric condition characterized by lifelong complex cognitive, emotional and behavioral phenotype. Although many individuals that experience trauma are able to gradually diminish their emotional responding to trauma-related stimuli over time, known as extinction learning, individuals suffering from PTSD are impaired in this capacity. An inability to decline this initially normal and adaptive fear response, can be confronted with exposure-based therapies, often in combination with pharmacological treatments. Due to the complexity of PTSD, currently available pharmacotherapeutics are inadequate in treating the deficient extinction observed in many PTSD patients. To develop novel therapeutics, researchers have exploited the conserved nature of fear and stress-associated behavioral responses and neurocircuits across species in an attempt to translate knowledge gained from preclinical studies into the clinic. There is growing evidence on the endocannabinoid modulation of fear and stress due to their 'on demand' synthesis and degradation. Involvement of the endocannabinoids in fear extinction makes the endocannabinoid system very attractive for finding effective therapeutics for trauma and stress related disorders. In this review, a brief introduction on neuroanatomy and circuitry of fear extinction will be provided as a model to study PTSD. Then, the endocannabinoid system will be discussed as an important component of extinction modulation. In this regard, anandamide degrading enzyme, fatty acid amide hydrolase (FAAH) will be exemplified as a target identified and validated strongly from preclinical to clinical translational studies of enhancing extinction.
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Affiliation(s)
- Ozge Gunduz-Cinar
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcoholism and Alcohol Abuse, NIH, Bethesda, MD, USA.
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The influence of rat strain on the development of neuropathic pain and comorbid anxio-depressive behaviour after nerve injury. Sci Rep 2020; 10:20981. [PMID: 33262364 PMCID: PMC7708988 DOI: 10.1038/s41598-020-77640-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 11/13/2020] [Indexed: 12/16/2022] Open
Abstract
Back-translating the clinical manifestations of human disease burden into animal models is increasingly recognized as an important facet of preclinical drug discovery. We hypothesized that inbred rat strains possessing stress hyper-reactive-, depressive- or anxiety-like phenotypes may possess more translational value than common outbred strains for modeling neuropathic pain. Rats (inbred: LEW, WKY, F344/ICO and F344/DU, outbred: Crl:SD) were exposed to Spared Nerve Injury (SNI) and evaluated routinely for 6 months on behaviours related to pain (von Frey stimulation and CatWalk-gait analysis), anxiety (elevated plus maze, EPM) and depression (sucrose preference test, SPT). Markers of stress reactivity together with spinal/brain opioid receptor expression were also measured. All strains variously developed mechanical allodynia after SNI with the exception of stress-hyporesponsive LEW rats, despite all strains displaying similar functional gait-deficits after injury. However, affective changes reflective of anxiety- and depressive-like behaviour were only observed for F344/DU in the EPM, and for Crl:SD in SPT. Although differences in stress reactivity and opioid receptor expression occurred, overall they were relatively unaffected by SNI. Thus, anxio-depressive behaviours did not develop in all strains after nerve injury, and correlated only modestly with degree of pain sensitivity or with genetic predisposition to stress and/or affective disturbances.
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Okine BN, Mc Laughlin G, Gaspar JC, Harhen B, Roche M, Finn DP. Antinociceptive Effects of the GPR55 Antagonist CID16020046 Injected into the Rat Anterior Cingulate Cortex. Neuroscience 2020; 443:19-29. [PMID: 32673629 DOI: 10.1016/j.neuroscience.2020.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 07/04/2020] [Accepted: 07/07/2020] [Indexed: 10/23/2022]
Abstract
The G-protein coupled receptor, GPR55, modulates nociceptive processing. Given the expression of GPR55 in the anterior cingulate cortex (ACC), a key brain region involved in the cognitive and affective dimensions of pain, the present study tested the hypothesis that GPR55 signalling in the ACC facilitates inflammatory pain behaviour in rats. The expression of GPR55 in the ACC was confirmed by both western blotting and immunostaining, with evidence for neuronal localisation. Microinjection of the selective GPR55 antagonist CID16020046 into the ACC of adult male Sprague-Dawley rats significantly reduced second phase formalin-evoked nociceptive behaviour compared with vehicle-treated controls. CID16020046 administration was associated with a reduction in phosphorylation of extracellular signal-regulated kinase (ERK), a downstream target of GPR55 activation, in the ACC. Intra-ACC administration of CID16020046 prevented the formalin-induced increases in expression of mRNA coding for the immediate early gene and marker of neuronal activity, c-Fos, in the ipsilateral dorsal horn of the spinal cord. Intra-plantar injection of formalin reduced tissue levels of the endogenous GPR55 ligand 2-arachidonoyl-sn-glycero-3-phosphoinositol (2-AGPI) in the ACC, likely reflecting its increased release/utilisation. These data suggest that endogenous activation of GPR55 signalling and increased ERK phosphorylation in the ACC facilitates inflammatory pain via top-down modulation of descending pain control.
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Affiliation(s)
- Bright N Okine
- Pharmacology and Therapeutics, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland; Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland
| | - Gemma Mc Laughlin
- Pharmacology and Therapeutics, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland
| | - Jessica C Gaspar
- Pharmacology and Therapeutics, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland; Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland
| | - Brendan Harhen
- Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland
| | - Michelle Roche
- Physiology, School of Medicine, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland; Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland; Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, University Road, Galway, Ireland.
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Corcoran L, Mattimoe D, Roche M, Finn DP. Attenuation of fear-conditioned analgesia in rats by monoacylglycerol lipase inhibition in the anterior cingulate cortex: Potential role for CB 2 receptors. Br J Pharmacol 2020; 177:2240-2255. [PMID: 31967664 PMCID: PMC7174879 DOI: 10.1111/bph.14976] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 12/01/2019] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Improved understanding of brain mechanisms regulating endogenous analgesia is important from a fundamental physiological perspective and for identification of novel therapeutic strategies for pain. The endocannabinoid system plays a key role in stress-induced analgesia, including fear-conditioned analgesia (FCA), a potent form of endogenous analgesia. Here, we studied the role of the endocannabinoid 2-arachidonoyl glycerol (2-AG) within the anterior cingulate cortex (ACC; a brain region implicated in the affective component of pain) in FCA in rats. EXPERIMENTAL APPROACH FCA was modelled in male Lister-hooded rats by assessing formalin-evoked nociceptive behaviour in an arena previously paired with footshock. The effects of intra-ACC administration of MJN110 (inhibitor of monoacylglycerol lipase [MGL], the primary enzyme catabolizing 2-AG), AM630 (CB2 receptor antagonist), AM251 (CB1 receptor antagonist) or MJN110 + AM630 on FCA were assessed. KEY RESULTS MJN110 attenuated FCA when microinjected into the ACC, an effect associated with increased levels of 2-AG in the ACC. This effect of MJN110 on FCA was unaltered by co-administration of AM251 but was blocked by AM630, which alone reduced nociceptive behaviour in non-fear-conditioned rats. RT-qPCR confirmed that mRNA encoding CB1 and CB2 receptors was detectable in the ACC of formalin-injected rats and unchanged in those expressing FCA. CONCLUSION AND IMPLICATIONS These results suggest that an MGL substrate in the ACC, likely 2-AG, modulates FCA and that within the ACC, 2-AG-CB2 receptor signalling may suppress this form of endogenous analgesia. These results may facilitate increased understanding and improved treatment of pain- and fear-related disorders and their co-morbidity.
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Affiliation(s)
- Louise Corcoran
- Pharmacology and Therapeutics, School of MedicineNational University of Ireland GalwayGalwayIreland
- Galway Neuroscience Centre and Centre for Pain ResearchNational University of Ireland GalwayGalwayIreland
| | - Darragh Mattimoe
- Pharmacology and Therapeutics, School of MedicineNational University of Ireland GalwayGalwayIreland
- Galway Neuroscience Centre and Centre for Pain ResearchNational University of Ireland GalwayGalwayIreland
| | - Michelle Roche
- Physiology, School of MedicineNational University of Ireland GalwayGalwayIreland
- Galway Neuroscience Centre and Centre for Pain ResearchNational University of Ireland GalwayGalwayIreland
| | - David P. Finn
- Pharmacology and Therapeutics, School of MedicineNational University of Ireland GalwayGalwayIreland
- Galway Neuroscience Centre and Centre for Pain ResearchNational University of Ireland GalwayGalwayIreland
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10
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Khan AU, Falconi-Sobrinho LL, Dos Anjos-Garcia T, de Fátima Dos Santos Sampaio M, de Souza Crippa JA, Menescal-de-Oliveira L, Coimbra NC. Cannabidiol-induced panicolytic-like effects and fear-induced antinociception impairment: the role of the CB 1 receptor in the ventromedial hypothalamus. Psychopharmacology (Berl) 2020; 237:1063-1079. [PMID: 31919563 DOI: 10.1007/s00213-019-05435-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 12/11/2019] [Indexed: 12/19/2022]
Abstract
RATIONALE The behavioural effects elicited by chemical constituents of Cannabis sativa, such as cannabidiol (CBD), on the ventromedial hypothalamus (VMH) are not well understood. There is evidence that VMH neurons play a relevant role in the modulation of unconditioned fear-related defensive behavioural reactions displayed by laboratory animals. OBJECTIVES This study was designed to explore the specific pattern of distribution of the CB1 receptors in the VMH and to investigate the role played by this cannabinoid receptor in the effect of CBD on the control of defensive behaviours and unconditioned fear-induced antinociception. METHODS A panic attack-like state was triggered in Wistar rats by intra-VMH microinjections of N-methyl-D-aspartate (NMDA). One of three different doses of CBD was microinjected into the VMH prior to local administration of NMDA. In addition, the most effective dose of CBD was used after pre-treatment with the CB1 receptor selective antagonist AM251, followed by NMDA microinjections in the VMH. RESULTS The morphological procedures demonstrated distribution of labelled CB1 receptors on neuronal perikarya situated in dorsomedial, central and ventrolateral divisions of the VMH. The neuropharmacological approaches showed that both panic attack-like behaviours and unconditioned fear-induced antinociception decreased after intra-hypothalamic microinjections of CBD at the highest dose (100 nmol). These effects, however, were blocked by the administration of the CB1 receptor antagonist AM251 (100 pmol) in the VMH. CONCLUSION These findings suggest that CBD causes panicolytic-like effects and reduces unconditioned fear-induced antinociception when administered in the VMH, and these effects are mediated by the CB1 receptor-endocannabinoid signalling mechanism in VMH.
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Affiliation(s)
- Asmat Ullah Khan
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.,Department of Eastern Medicine and Surgery, School of Medical and Health Sciences, The University of Poonch Rawalakot, Hajira Road, Shamsabad, Rawalakot, Azad Jammu & Kashmir, 12350, Pakistan.,Neurobiology of Emotions (NAP-USP-NuPNE) Research Centre, Ribeirão Preto School of Medicine of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Luiz Luciano Falconi-Sobrinho
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.,Neurobiology of Emotions (NAP-USP-NuPNE) Research Centre, Ribeirão Preto School of Medicine of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.,Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto, São Paulo, 4220-030, Brazil
| | - Tayllon Dos Anjos-Garcia
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.,Neurobiology of Emotions (NAP-USP-NuPNE) Research Centre, Ribeirão Preto School of Medicine of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Maria de Fátima Dos Santos Sampaio
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - José Alexandre de Souza Crippa
- Department of Neuroscience and Behavioural Sciences, Division of Psychiatry, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Leda Menescal-de-Oliveira
- Neurobiology of Emotions (NAP-USP-NuPNE) Research Centre, Ribeirão Preto School of Medicine of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.,Laboratory of Neurophysiology, Department of Physiology, Ribeirão Preto Medical School of the University of São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Norberto Cysne Coimbra
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil. .,Neurobiology of Emotions (NAP-USP-NuPNE) Research Centre, Ribeirão Preto School of Medicine of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil. .,Behavioural Neurosciences Institute (INeC), Avenida do Café, 2450, Ribeirão Preto, São Paulo, 4220-030, Brazil.
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11
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Gaspar JC, Okine BN, Llorente-Berzal A, Roche M, Finn DP. Pharmacological Blockade of PPAR Isoforms Increases Conditioned Fear Responding in the Presence of Nociceptive Tone. Molecules 2020; 25:molecules25041007. [PMID: 32102354 PMCID: PMC7070536 DOI: 10.3390/molecules25041007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 12/29/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors with three isoforms (PPARα, PPARβ/δ, PPARγ) and can regulate pain, anxiety, and cognition. However, their role in conditioned fear and pain-fear interactions has not yet been investigated. Here, we investigated the effects of systemically administered PPAR antagonists on formalin-evoked nociceptive behaviour, fear-conditioned analgesia (FCA), and conditioned fear in the presence of nociceptive tone in rats. Twenty-three and a half hours following fear conditioning to context, male Sprague-Dawley rats received an intraplantar injection of formalin and intraperitoneal administration of vehicle, PPARα (GW6471), PPARβ/δ (GSK0660) or PPARγ (GW9662) antagonists, and 30 min later were re-exposed to the conditioning arena for 15 min. The PPAR antagonists did not alter nociceptive behaviour or fear-conditioned analgesia. The PPARα and PPARβ/δ antagonists prolonged context-induced freezing in the presence of nociceptive tone without affecting its initial expression. The PPARγ antagonist potentiated freezing over the entire trial. In conclusion, pharmacological blockade of PPARα and PPARβ/δ in the presence of formalin-evoked nociceptive tone, impaired short-term, within-trial fear-extinction in rats without affecting pain response, while blockade of PPARγ potentiated conditioned fear responding. These results suggest that endogenous signalling through these three PPAR isoforms may reduce the expression of conditioned fear in the presence of nociceptive tone.
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Affiliation(s)
- Jessica C. Gaspar
- Pharmacology and Therapeutics Department, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland; (J.C.G.); (B.N.O.); (A.L.-B.)
- Galway Neuroscience Centre, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland
| | - Bright N. Okine
- Pharmacology and Therapeutics Department, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland; (J.C.G.); (B.N.O.); (A.L.-B.)
- Galway Neuroscience Centre, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland
| | - Alvaro Llorente-Berzal
- Pharmacology and Therapeutics Department, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland; (J.C.G.); (B.N.O.); (A.L.-B.)
- Galway Neuroscience Centre, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland
| | - Michelle Roche
- Galway Neuroscience Centre, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland
- Physiology Department, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland
| | - David P. Finn
- Pharmacology and Therapeutics Department, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland; (J.C.G.); (B.N.O.); (A.L.-B.)
- Galway Neuroscience Centre, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland;
- Physiology Department, National University of Ireland Galway, University Road, H91 W5P7 Galway, Ireland
- Correspondence: ; Tel.: +353-(0)91-495-280; Fax: +353-(0)91-495-586
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12
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González de San Román E, Manuel I, Ledent C, Chun J, Rodríguez de Fonseca F, Estivill-Torrús G, Santín LJ, Rodríguez Puertas R. CB 1 and LPA 1 Receptors Relationship in the Mouse Central Nervous System. Front Mol Neurosci 2019; 12:223. [PMID: 31607860 PMCID: PMC6761275 DOI: 10.3389/fnmol.2019.00223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 09/03/2019] [Indexed: 01/29/2023] Open
Abstract
Neurolipids are a class of bioactive lipids that are produced locally through specific biosynthetic pathways in response to extracellular stimuli. Neurolipids are important endogenous regulators of neural cell proliferation, differentiation, oxidative stress, inflammation and apoptosis. Endocannabinoids (eCBs) and lysophosphatidic acid (LPA) are examples of this type of molecule and are involved in neuroprotection. The present study analyzes a possible relationship of the main receptor subtypes for both neurolipid systems that are present in the central nervous system, the CB1 and LPA1 receptors, by using brain slices from CB1 KO mice and LPA1-null mice. Receptor-mediated G protein activation and glycerophospholipid regulation of potential precursors of their endogenous neurotransmitters were measured by two different in vitro imaging techniques, functional autoradiography and imaging mass spectrometry (IMS), respectively. Possible crosstalk between CB1 and LPA1 receptors was identified in specific areas of the brain, such as the amygdala, where LPA1 receptor activity is upregulated in CB1 KO mice. More evidence of an interaction between both systems was that the CB1-mediated activity was clearly increased in the prefrontal cortex and cerebellum of LPA1-null mice. The eCB system was specifically over-activated in regions where LPA1 has an important signaling role during embryonic development. The modifications on phospholipids (PLs) observed in these genetically modified mice by using the IMS technique indicated the regulation of some of the PL precursors of both LPA and eCBs in specific brain areas. For example, phosphatidylcholine (PC) (36:1) was detected as a potential LPA precursor, and phosphatidylethanolamine (PE) (40:6) and PE (p18:0/22:6) as potential eCB precursors. The absence of the main cerebral receptors for LPA or eCB systems is able to induce modulation on the other at the levels of both signaling and synthesis of endogenous neurotransmitters, indicating adaptive responses between both systems during prenatal and/or postnatal development.
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Affiliation(s)
| | - Iván Manuel
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Catherine Ledent
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Jerold Chun
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, United States
| | - Fernando Rodríguez de Fonseca
- Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain, 5 Unidad de Gestión Clínica de Salud Mental, Málaga, Spain.,Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Universidad de Málaga, Málaga, Spain
| | - Guillermo Estivill-Torrús
- Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain, 5 Unidad de Gestión Clínica de Salud Mental, Málaga, Spain.,Unidad de Gestión Clínica de Neurociencias, Hospital Regional Universitario de Málaga, Málaga, Spain
| | - Luis Javier Santín
- Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain, 5 Unidad de Gestión Clínica de Salud Mental, Málaga, Spain.,Departamento de Psicobiología y Metodología de las Ciencias del Comportamiento, Universidad de Málaga, Málaga, Spain
| | - Rafael Rodríguez Puertas
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain.,Neurodegenerative Diseases, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
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13
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Lee JLC, Amorim FE, Cassini LF, Amaral OB. Different temporal windows for CB1 receptor involvement in contextual fear memory destabilisation in the amygdala and hippocampus. PLoS One 2019; 14:e0205781. [PMID: 30645588 PMCID: PMC6333379 DOI: 10.1371/journal.pone.0205781] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 12/26/2018] [Indexed: 12/24/2022] Open
Abstract
Reconsolidation is a process in which re-exposure to a reminder causes a previously acquired memory to undergo a process of destabilisation followed by subsequent restabilisation. Different molecular mechanisms have been postulated for destabilisation in the amygdala and hippocampus, including CB1 receptor activation, protein degradation and AMPA receptor exchange; however, most of the amygdala studies have used pre-reexposure interventions, while those in the hippocampus have usually performed them after reexposure. To test whether the temporal window for destabilisation is similar across both structures, we trained Lister Hooded rats in a contextual fear conditioning task, and 1 day later performed memory reexposure followed by injection of either the NMDA antagonist MK-801 (0.1 mg/kg) or saline in order to block reconsolidation. In parallel, we also performed local injections of either the CB1 antagonist SR141716A or its vehicle in the hippocampus or in the amygdala, either immediately before or immediately after reactivation. Infusion of SR141716A in the hippocampus prevented the reconsolidation-blocking effect of MK-801 when performed after reexposure, but not before it. In the amygdala, meanwhile, pre-reexposure infusions of SR141716A impaired reconsolidation blockade by MK-801, although the time-dependency of this effect was not as clear as in the hippocampus. Our results suggest the temporal windows for CB1-receptor-mediated memory destabilisation during reconsolidation vary between brain structures. Whether this reflects different time windows for engagement of these structures or different roles played by CB1 receptors in destabilisation across structures remains an open question for future studies.
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MESH Headings
- Amygdala/drug effects
- Amygdala/physiology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Cannabinoid Receptor Antagonists/administration & dosage
- Conditioning, Classical/drug effects
- Dizocilpine Maleate/administration & dosage
- Excitatory Amino Acid Antagonists/administration & dosage
- Fear/drug effects
- Fear/physiology
- Hippocampus/drug effects
- Hippocampus/physiology
- Male
- Memory/drug effects
- Memory/physiology
- Models, Animal
- Rats
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/metabolism
- Rimonabant/administration & dosage
- Time Factors
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Affiliation(s)
- Jonathan L. C. Lee
- University of Birmingham, School of Psychology, Edgbaston, Birmingham, United Kingdom
- * E-mail:
| | - Felippe E. Amorim
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lindsey F. Cassini
- University of Birmingham, School of Psychology, Edgbaston, Birmingham, United Kingdom
| | - Olavo B. Amaral
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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14
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Lisboa SF, Vila-Verde C, Rosa J, Uliana DL, Stern CAJ, Bertoglio LJ, Resstel LB, Guimaraes FS. Tempering aversive/traumatic memories with cannabinoids: a review of evidence from animal and human studies. Psychopharmacology (Berl) 2019; 236:201-226. [PMID: 30604182 DOI: 10.1007/s00213-018-5127-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 11/14/2018] [Indexed: 01/08/2023]
Abstract
RATIONALE Aversive learning and memory are essential to cope with dangerous and stressful stimuli present in an ever-changing environment. When this process is dysfunctional, however, it is associated with posttraumatic stress disorder (PTSD). The endocannabinoid (eCB) system has been implicated in synaptic plasticity associated with physiological and pathological aversive learning and memory. OBJECTIVE AND METHODS The objective of this study was to review and discuss evidence on how and where in the brain genetic or pharmacological interventions targeting the eCB system would attenuate aversive/traumatic memories through extinction facilitation in laboratory animals and humans. The effect size of the experimental intervention under investigation was also calculated. RESULTS Currently available data indicate that direct or indirect activation of cannabinoid type-1 (CB1) receptor facilitates the extinction of aversive/traumatic memories. Activating CB1 receptors around the formation of aversive/traumatic memories or their reminders can potentiate their subsequent extinction. In most cases, the effect size has been large (Cohen's d ≥ 1.0). The brain areas responsible for the abovementioned effects include the medial prefrontal cortex, amygdala, and/or hippocampus. The potential role of cannabinoid type-2 (CB2) receptors in extinction learning is now under investigation. CONCLUSION Drugs augmenting the brain eCB activity can temper the impact of aversive/traumatic experiences by diverse mechanisms depending on the moment of their administration. Considering the pivotal role the extinction process plays in PTSD, the therapeutic potential of these drugs is evident. The sparse number of clinical trials testing these compounds in stress-related disorders is a gap in the literature that needs to be addressed.
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Affiliation(s)
- Sabrina F Lisboa
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Av Bandeirantes 3900, Monte Alegre, 14049900, Ribeirão Preto, São Paulo, Brazil. .,Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), Medical School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.
| | - C Vila-Verde
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Av Bandeirantes 3900, Monte Alegre, 14049900, Ribeirão Preto, São Paulo, Brazil.,Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), Medical School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - J Rosa
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Av Bandeirantes 3900, Monte Alegre, 14049900, Ribeirão Preto, São Paulo, Brazil.,Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), Medical School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - D L Uliana
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Av Bandeirantes 3900, Monte Alegre, 14049900, Ribeirão Preto, São Paulo, Brazil.,Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), Medical School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - C A J Stern
- Department of Pharmacology, Federal University of Parana, Curitiba, PR, Brazil
| | - L J Bertoglio
- Department of Pharmacology, Federal University of Santa Catarina, Florianopolis, SC, Brazil
| | - L B Resstel
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Av Bandeirantes 3900, Monte Alegre, 14049900, Ribeirão Preto, São Paulo, Brazil.,Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), Medical School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - F S Guimaraes
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Av Bandeirantes 3900, Monte Alegre, 14049900, Ribeirão Preto, São Paulo, Brazil.,Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), Medical School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
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15
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Rea K, McGowan F, Corcoran L, Roche M, Finn DP. The prefrontal cortical endocannabinoid system modulates fear-pain interactions in a subregion-specific manner. Br J Pharmacol 2018; 176:1492-1505. [PMID: 29847859 DOI: 10.1111/bph.14376] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 05/11/2018] [Accepted: 05/15/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE The emotional processing and coordination of top-down responses to noxious and conditioned aversive stimuli involves the medial prefrontal cortex (mPFC). Evidence suggests that subregions of the mPFC [infralimbic (IfL), prelimbic (PrL) and anterior cingulate (ACC) cortices] differentially alter the expression of contextually induced fear and nociceptive behaviour. We investigated the role of the endocannabinoid system in the IfL, PrL and ACC in formalin-evoked nociceptive behaviour, fear-conditioned analgesia (FCA) and conditioned fear in the presence of nociceptive tone. EXPERIMENTAL APPROACH FCA was modelled in male Lister-hooded rats by assessing formalin-evoked nociceptive behaviour in an arena previously paired with footshock. The effects of intra-mPFC administration of AM251 [cannabinoid type 1 (CB1 ) receptor antagonist/inverse agonist], URB597 [fatty acid amide hydrolase (FAAH) inhibitor] or URB597 + AM251 on FCA and freezing behaviour were assessed. KEY RESULTS AM251 attenuated FCA when injected into the IfL or PrL and reduced contextually induced freezing behaviour when injected intra-IfL but not intra-PrL or intra-ACC. Intra-ACC administration of AM251 alone or in combination with URB597 had no effect on FCA or freezing. URB597 attenuated FCA and freezing behaviour when injected intra-IfL, prolonged the expression of FCA when injected intra-PrL and had no effect on these behaviours when injected intra-ACC. CONCLUSIONS AND IMPLICATIONS These results suggest important and differing roles for FAAH substrates or CB1 receptors in the PrL, IfL and ACC in the expression of FCA and conditioned fear in the presence of nociceptive tone. LINKED ARTICLES This article is part of a themed section on 8th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc.
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Affiliation(s)
- Kieran Rea
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, Galway, Ireland
| | - Fiona McGowan
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, Galway, Ireland
| | - Louise Corcoran
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, Galway, Ireland
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland Galway, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, Galway, Ireland
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16
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Krabbe S, Gründemann J, Lüthi A. Amygdala Inhibitory Circuits Regulate Associative Fear Conditioning. Biol Psychiatry 2018; 83:800-809. [PMID: 29174478 DOI: 10.1016/j.biopsych.2017.10.006] [Citation(s) in RCA: 162] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/28/2017] [Accepted: 10/04/2017] [Indexed: 11/16/2022]
Abstract
Associative memory formation is essential for an animal's survival by ensuring adaptive behavioral responses in an ever-changing environment. This is particularly important under conditions of immediate threats such as in fear learning. One of the key brain regions involved in associative fear learning is the amygdala. The basolateral amygdala is the main entry site for sensory information to the amygdala complex, and local plasticity in excitatory basolateral amygdala principal neurons is considered to be crucial for learning of conditioned fear responses. However, activity and plasticity of excitatory circuits are tightly controlled by local inhibitory interneurons in a spatially and temporally defined manner. In this review, we provide an updated view on how distinct interneuron subtypes in the basolateral amygdala contribute to the acquisition and extinction of conditioned fear memories.
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Affiliation(s)
- Sabine Krabbe
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jan Gründemann
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Lüthi
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
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17
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Stern CA, de Carvalho CR, Bertoglio LJ, Takahashi RN. Effects of Cannabinoid Drugs on Aversive or Rewarding Drug-Associated Memory Extinction and Reconsolidation. Neuroscience 2018; 370:62-80. [DOI: 10.1016/j.neuroscience.2017.07.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/23/2017] [Accepted: 07/09/2017] [Indexed: 12/22/2022]
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18
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Schafer SM, Geuter S, Wager TD. Mechanisms of placebo analgesia: A dual-process model informed by insights from cross-species comparisons. Prog Neurobiol 2018; 160:101-122. [PMID: 29108801 PMCID: PMC5747994 DOI: 10.1016/j.pneurobio.2017.10.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 10/24/2017] [Accepted: 10/28/2017] [Indexed: 12/19/2022]
Abstract
Placebo treatments are pharmacologically inert, but are known to alleviate symptoms across a variety of clinical conditions. Associative learning and cognitive expectations both play important roles in placebo responses, however we are just beginning to understand how interactions between these processes lead to powerful effects. Here, we review the psychological principles underlying placebo effects and our current understanding of their brain bases, focusing on studies demonstrating both the importance of cognitive expectations and those that demonstrate expectancy-independent associative learning. To account for both forms of placebo analgesia, we propose a dual-process model in which flexible, contextually driven cognitive schemas and attributions guide associative learning processes that produce stable, long-term placebo effects. According to this model, the placebo-induction paradigms with the most powerful effects are those that combine reinforcement (e.g., the experience of reduced pain after placebo treatment) with suggestions and context cues that disambiguate learning by attributing perceived benefit to the placebo. Using this model as a conceptual scaffold, we review and compare neurobiological systems identified in both human studies of placebo analgesia and behavioral pain modulation in rodents. We identify substantial overlap between the circuits involved in human placebo analgesia and those that mediate multiple forms of context-based modulation of pain behavior in rodents, including forebrain-brainstem pathways and opioid and cannabinoid systems in particular. This overlap suggests that placebo effects are part of a set of adaptive mechanisms for shaping nociceptive signaling based on its information value and anticipated optimal response in a given behavioral context.
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Affiliation(s)
- Scott M Schafer
- Department of Psychology and Neuroscience, University of Colorado, 345 UCB, Boulder, CO 80309, USA
| | - Stephan Geuter
- Department of Psychology and Neuroscience, University of Colorado, 345 UCB, Boulder, CO 80309, USA; Institute of Cognitive Science, University of Colorado Boulder, 344 UCB, Boulder, CO 80309, USA; Department of Biostatistics, Johns Hopkins University, 615 N Wolfe St, Baltimore, MD 21205, USA
| | - Tor D Wager
- Department of Psychology and Neuroscience, University of Colorado, 345 UCB, Boulder, CO 80309, USA; Institute of Cognitive Science, University of Colorado Boulder, 344 UCB, Boulder, CO 80309, USA.
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N-palmitoylethanolamide in the anterior cingulate cortex attenuates inflammatory pain behaviour indirectly via a CB1 receptor-mediated mechanism. Pain 2017; 157:2687-2696. [PMID: 27649266 DOI: 10.1097/j.pain.0000000000000687] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The neural substrates and mechanisms mediating the antinociceptive effects of the endogenous bioactive lipid, N-palmitoylethanolamide (PEA), require further investigation. We investigated the effects of exogenous PEA administration into the anterior cingulate cortex (ACC), an important brain region linked with cognitive and affective modulation of pain, on formalin-evoked nociceptive behaviour in rats. Potential involvement of peroxisome proliferator-activated receptor isoforms (PPAR) α and γ or endocannabinoid-mediated entourage effects at cannabinoid1 (CB1) receptors or transient receptor potential subfamily V member 1 (TRPV1) in mediating the effects of PEA was also investigated. Intra-ACC administration of PEA significantly attenuated the first and early second phases of formalin-evoked nociceptive behaviour. This effect was attenuated by the CB1 receptor antagonist AM251, but not by the PPARα antagonist GW6471, the PPARγ antagonist GW9662, or the TRPV1 antagonist 5'-iodo resiniferatoxin. All antagonists, administered alone, significantly reduced formalin-evoked nociceptive behaviour, suggesting facilitatory/permissive roles for these receptors in the ACC in inflammatory pain. Post-mortem tissue analysis revealed a strong trend for increased levels of the endocannabinoid anandamide in the ACC of rats that received intra-ACC PEA. Expression of c-Fos, a marker of neuronal activity, was significantly reduced in the basolateral nucleus of the amygdala, but not in the central nucleus of the amygdala, the rostral ventromedial medulla or the dorsal horn of the spinal cord. In conclusion, these data indicate that PEA in the ACC can reduce inflammatory pain-related behaviour, possibly via AEA-induced activation of CB1 receptors and associated modulation of neuronal activity in the basolateral amygdala.
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Woodhams SG, Chapman V, Finn DP, Hohmann AG, Neugebauer V. The cannabinoid system and pain. Neuropharmacology 2017; 124:105-120. [PMID: 28625720 PMCID: PMC5785108 DOI: 10.1016/j.neuropharm.2017.06.015] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/31/2017] [Accepted: 06/14/2017] [Indexed: 01/20/2023]
Abstract
Chronic pain states are highly prevalent and yet poorly controlled by currently available analgesics, representing an enormous clinical, societal, and economic burden. Existing pain medications have significant limitations and adverse effects including tolerance, dependence, gastrointestinal dysfunction, cognitive impairment, and a narrow therapeutic window, making the search for novel analgesics ever more important. In this article, we review the role of an important endogenous pain control system, the endocannabinoid (EC) system, in the sensory, emotional, and cognitive aspects of pain. Herein, we briefly cover the discovery of the EC system and its role in pain processing pathways, before concentrating on three areas of current major interest in EC pain research; 1. Pharmacological enhancement of endocannabinoid activity (via blockade of EC metabolism or allosteric modulation of CB1receptors); 2. The EC System and stress-induced modulation of pain; and 3. The EC system & medial prefrontal cortex (mPFC) dysfunction in pain states. Whilst we focus predominantly on the preclinical data, we also include extensive discussion of recent clinical failures of endocannabinoid-related therapies, the future potential of these approaches, and important directions for future research on the EC system and pain. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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Affiliation(s)
- Stephen G Woodhams
- Arthritis UK Pain Centre, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom.
| | - Victoria Chapman
- Arthritis UK Pain Centre, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - David P Finn
- Pharmacology & Therapeutics, School of Medicine, Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, University Road, Galway, Ireland
| | - Andrea G Hohmann
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Program in Neuroscience, Indiana University, Bloomington, IN, USA; Interdisciplinary Biochemistry Graduate Program, Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA; Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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Varga B, Kassai F, Szabó G, Kovács P, Fischer J, Gyertyán I. Pharmacological comparison of traditional and non-traditional cannabinoid receptor 1 blockers in rodent models in vivo. Pharmacol Biochem Behav 2017; 159:24-35. [PMID: 28666894 DOI: 10.1016/j.pbb.2017.06.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Revised: 04/29/2017] [Accepted: 06/26/2017] [Indexed: 01/07/2023]
Abstract
Cannabinoid receptor 1 (CB1R) antagonists have been proven to be effective anti-obesity drugs; however, psychiatric side effects have halted their pharmaceutical development worldwide. Despite the emergence of next generation CB1R blockers, a preclinical head to head comparison of the anti-obesity and psychiatric side effect profiles of the key compounds has not been performed. Here, we compared classical CB1R antagonists (rimonabant, taranabant, otenabant, ibipinabant, and surinabant) and non-traditional CB1R blockers (the partial agonist O-1269, the neutral antagonists VCHSR and LH-21 and the peripherally acting inverse agonist JD-5037) using an in vivo screening cascade. First, the potencies of these compounds to reduce CB1R agonist-induced hypothermia and decrease fasting-induced food intake were determined. Then, equipotent doses of the non-toxic compounds were compared in a diet-induced obesity (DIO) test, which includes measurements of metabolic syndrome markers. Psychiatric side effects were assessed by measuring anxiogenicity in an ultrasonic vocalization test. All classical CB1R blockers were centrally acting appetite suppressants and decreased body weight and food intake in an obesity-dependent manner, with only slight effects on metabolic syndrome markers. In addition, all classical CB1R blockers increased ultrasonic vocalization. Surprisingly, none of the non-classical CB1R blockers was eligible for the DIO comparison and side effect profiling. O-1269 and LH-21 induced convulsive behavior, whereas VCHSR and JD-5037 were devoid of any in vivo activity. The classical CB1R blockers displayed similar therapeutic and side effect profiles in vivo, whereas the available non-traditional CB1R blockers were not appropriate tools for testing the therapeutic potential of alternative CB1R inhibitors.
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Affiliation(s)
- Balázs Varga
- Gedeon Richter Plc, 10, PO Box 27, H-1475 Budapest, , Hungary.
| | - Ferenc Kassai
- MTA-SE NAP B Cognitive Translational Behavioural Pharmacology Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Nagyvárad tér 4, H-1089, Budapest, Hungary; Hungarian Academy of Sciences, Research Centre of Natural Science, Institute of Cognitive Neuroscience and Psychology, Magyar tudósok körútja 2, H-1117 Budapset, Hungary
| | - György Szabó
- Gedeon Richter Plc, 10, PO Box 27, H-1475 Budapest, , Hungary
| | - Péter Kovács
- Berlin-Chemie/A. Menarini Magyarország Kft., Neumann János u. 1. H-2040 Budaörs, Hungary
| | - János Fischer
- Gedeon Richter Plc, 10, PO Box 27, H-1475 Budapest, , Hungary
| | - István Gyertyán
- MTA-SE NAP B Cognitive Translational Behavioural Pharmacology Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Nagyvárad tér 4, H-1089, Budapest, Hungary; Hungarian Academy of Sciences, Research Centre of Natural Science, Institute of Cognitive Neuroscience and Psychology, Magyar tudósok körútja 2, H-1117 Budapset, Hungary
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Starowicz K, Finn DP. Cannabinoids and Pain: Sites and Mechanisms of Action. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 80:437-475. [PMID: 28826543 DOI: 10.1016/bs.apha.2017.05.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The endocannabinoid system, consisting of the cannabinoid1 receptor (CB1R) and cannabinoid2 receptor (CB2R), endogenous cannabinoid ligands (endocannabinoids), and metabolizing enzymes, is present throughout the pain pathways. Endocannabinoids, phytocannabinoids, and synthetic cannabinoid receptor agonists have antinociceptive effects in animal models of acute, inflammatory, and neuropathic pain. CB1R and CB2R located at peripheral, spinal, or supraspinal sites are important targets mediating these antinociceptive effects. The mechanisms underlying the analgesic effects of cannabinoids likely include inhibition of presynaptic neurotransmitter and neuropeptide release, modulation of postsynaptic neuronal excitability, activation of the descending inhibitory pain pathway, and reductions in neuroinflammatory signaling. Strategies to dissociate the psychoactive effects of cannabinoids from their analgesic effects have focused on peripherally restricted CB1R agonists, CB2R agonists, inhibitors of endocannabinoid catabolism or uptake, and modulation of other non-CB1R/non-CB2R targets of cannabinoids including TRPV1, GPR55, and PPARs. The large body of preclinical evidence in support of cannabinoids as potential analgesic agents is supported by clinical studies demonstrating their efficacy across a variety of pain disorders.
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Affiliation(s)
- Katarzyna Starowicz
- Institute of Pharmacology, Polish Academy of Sciences, Laboratory of Pain Pathophysiology, Krakow, Poland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland.
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Endocannabinoid System: the Direct and Indirect Involvement in the Memory and Learning Processes-a Short Review. Mol Neurobiol 2016; 54:8332-8347. [PMID: 27924524 PMCID: PMC5684264 DOI: 10.1007/s12035-016-0313-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 11/21/2016] [Indexed: 11/24/2022]
Abstract
The endocannabinoid system via cannabinoid (CB: CB1 and CB2) receptors and their endogenous ligands is directly and indirectly involved in many physiological functions, especially in memory and learning processes. Extensive studies reported that this system strictly modulates cognition-related processes evaluated in various animal models. However, the effects of cannabinoids on the cognition have been contradictory. The cannabinoid compounds were able to both impair or improve different phases of memory processes through direct (receptor related) or indirect (non-receptor related) mechanism. The memory-related effects induced by the cannabinoids can be depended on the kind of cannabinoid compound used, dosage, and route of administration as well as on the memory task chosen. Therefore, the objectives of this paper are to review and summarize the results describing the role of endocannabinoid system in cognition, including various stages of memory.
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Repeated forced swim stress differentially affects formalin-evoked nociceptive behaviour and the endocannabinoid system in stress normo-responsive and stress hyper-responsive rat strains. Prog Neuropsychopharmacol Biol Psychiatry 2016; 64:181-9. [PMID: 25988529 DOI: 10.1016/j.pnpbp.2015.05.008] [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: 01/23/2015] [Revised: 05/09/2015] [Accepted: 05/11/2015] [Indexed: 01/18/2023]
Abstract
Repeated exposure to a homotypic stressor such as forced swimming enhances nociceptive responding in rats. However, the influence of genetic background on this stress-induced hyperalgesia is poorly understood. The aim of the present study was to compare the effects of repeated forced swim stress on nociceptive responding in Sprague-Dawley (SD) rats versus the Wistar Kyoto (WKY) rat strain, a genetic background that is susceptible to stress, negative affect and hyperalgesia. Given the well-documented role of the endocannabinoid system in stress and pain, we investigated associated alterations in endocannabinoid signalling in the dorsal horn of the spinal cord and amygdala. In SD rats, repeated forced swim stress for 10 days was associated with enhanced late phase formalin-evoked nociceptive behaviour, compared with naive, non-stressed SD controls. In contrast, WKY rats exposed to 10 days of swim stress displayed reduced late phase formalin-evoked nociceptive behaviour. Swim stress increased levels of monoacylglycerol lipase (MAGL) mRNA in the ipsilateral side of the dorsal spinal cord of SD rats, an effect not observed in WKY rats. In the amygdala, swim stress reduced anandamide (AEA) levels in the contralateral amygdala of SD rats, but not WKY rats. Additional within-strain differences in levels of CB1 receptor and fatty acid amide hydrolase (FAAH) mRNA and levels of 2-arachidonylglycerol (2-AG) were observed between the ipsilateral and contralateral sides of the dorsal horn and/or amygdala. These data indicate that the effects of repeated stress on inflammatory pain-related behaviour are different in two rat strains that differ with respect to stress responsivity and affective state and implicate the endocannabinoid system in the spinal cord and amygdala in these differences.
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Rabinak CA, Phan KL. Cannabinoid modulation of fear extinction brain circuits: a novel target to advance anxiety treatment. Curr Pharm Des 2015; 20:2212-7. [PMID: 23829364 DOI: 10.2174/13816128113199990437] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 06/10/2013] [Indexed: 12/26/2022]
Abstract
Anxiety disorders, such as post-traumatic stress (PTSD), panic, and phobic disorders, can be conceptualized as a failure to inhibit inappropriate fear responses. A common, effective treatment strategy involves repeated presentations to the feared cue without any danger (extinction). However, extinction learning has a number of important limitations, and enhancing its effects, generalizability and durability via cognitive enhancers may improve its therapeutic impact. In this review we focus specifically on the role of the cannabinoid system in fear extinction learning and its retention. We address the following questions: What are the neural circuits mediating fear extinction?; Can we make fear extinction more effective?; Can cannabinoids facilitate fear extinction in humans?; How might the cannabinoid system effect fear extinction? Collectively, translational evidence suggest that enhancing cannabinoid transmission may facilitate extinction learning and its recall, and that the cannabinoid system is a potential pharmacological target for improving the active learning that occurs during exposure-based behavioral treatments prompting future research in terms of mechanisms research, novel treatment approaches ('cognitive enhancers'), and pharmacotherapeutic drug discovery.
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Affiliation(s)
| | - K Luan Phan
- Department of Psychiatry, University of Michigan, Rachel Upjohn Building, 4250 Plymouth Road, Ann Arbor, MI 48109-2700.
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Corcoran L, Roche M, Finn DP. The Role of the Brain's Endocannabinoid System in Pain and Its Modulation by Stress. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 125:203-55. [DOI: 10.1016/bs.irn.2015.10.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Okine BN, Rea K, Olango WM, Price J, Herdman S, Madasu MK, Roche M, Finn DP. A role for PPARα in the medial prefrontal cortex in formalin-evoked nociceptive responding in rats. Br J Pharmacol 2014; 171:1462-71. [PMID: 24303983 DOI: 10.1111/bph.12540] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 10/02/2013] [Accepted: 10/27/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE The nuclear hormone receptor, PPARα, and its endogenous ligands, are involved in pain modulation. PPARα is expressed in the medial prefrontal cortex (mPFC), a key brain region involved in both the cognitive-affective component of pain and in descending modulation of pain. However, the role of PPARα in the mPFC in pain responding has not been investigated. Here, we investigated the effects of pharmacological modulation of PPARα in the rat mPFC on formalin-evoked nociceptive behaviour and the impact of formalin-induced nociception on components of PPARα signalling in the mPFC. EXPERIMENTAL APPROACH The effects of intra-mPFC microinjection of a PPARα agonist (GW7647) or a PPARα antagonist (GW6471) on formalin-evoked nociceptive behaviour in rats were studied. Quantitative real-time PCR and LC-MS/MS were used to study the effects of intraplantar injection of formalin on PPARα mRNA expression and levels of endogenous ligands, respectively, in the mPFC. KEY RESULTS Intra-mPFC administration of GW6471, but not GW7647, resulted in delayed onset of the early second phase of formalin-evoked nociceptive behaviour. Furthermore, formalin-evoked nociceptive behaviour was associated with significant reductions in mPFC levels of endogenous PPARα ligands (N-palmitoylethanolamide and N-oleoylethanolamide) and a 70% reduction in PPARα mRNA but not protein expression. CONCLUSIONS AND IMPLICATIONS These data suggest that endogenous ligands may act at PPARα in the mPFC to play a facilitatory/permissive role in second phase formalin-evoked nociceptive behaviour in rats. LINKED ARTICLES This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.
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Affiliation(s)
- B N Okine
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Galway, Ireland; Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland Galway, Galway, Ireland
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Rea K, Ford GK, Olango WM, Harhen B, Roche M, Finn DP. Microinjection of 2-arachidonoyl glycerol into the rat ventral hippocampus differentially modulates contextually induced fear, depending on a persistent pain state. Eur J Neurosci 2014; 39:435-43. [PMID: 24494683 DOI: 10.1111/ejn.12452] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/09/2013] [Accepted: 11/11/2013] [Indexed: 12/19/2022]
Abstract
The endogenous cannabinoid (endocannabinoid) system plays a key role in the modulation of aversive and nociceptive behaviour. The components of the endocannabinoid system are expressed throughout the hippocampus, a brain region implicated in both conditioned fear and pain. In light of evidence that pain can impact on the expression of fear-related behaviour, and vice versa, we hypothesised that exogenous administration of the endocannabinoid 2-arachidonoyl glycerol (2-AG) into the ventral hippocampus (vHip) would differentially regulate fear responding in the absence vs. the presence of formalin-evoked nociceptive tone. Fear-conditioned rats showed significantly increased freezing and a reduction in formalin-evoked nociceptive behaviour upon re-exposure to a context previously paired with footshock. Bilateral microinjection of 2-AG into the vHip significantly reduced contextually induced freezing in non-formalin-treated rats, and reduced formalin-evoked nociceptive behaviour in non-fear-conditioned rats. In contrast, 2-AG microinjection had no effect on fear responding in formalin-treated rats, and no effect on nociceptive behaviour in fear-conditioned rats. The inhibitory effect of 2-AG on fear-related behaviour, but not pain-related behaviour, was blocked by co-administration of the cannabinoid receptor 1 (CB1) antagonist/inverse agonist rimonabant. Tissue levels of the endocannabinoids N-arachidonoylethanolamide (anandamide, AEA) and 2-AG were similar in the vHip of fear-conditioned rats receiving formalin injection and the vHip of fear-conditioned rats receiving saline injection. However, the levels of AEA and 2-AG were significantly lower in the contralateral ventrolateral periaqueductal grey of formalin-treated fear-conditioned rats than in that of their saline-treated counterparts. These data suggest that 2-AG-CB1 receptor signalling in the vHip has an anti-aversive effect, and that this effect is abolished in the presence of a persistent pain state.
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Affiliation(s)
- Kieran Rea
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, University Road, Galway, Ireland; Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland
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Xing G, Carlton J, Jiang X, Wen J, Jia M, Li H. Differential Expression of Brain Cannabinoid Receptors between Repeatedly Stressed Males and Females may Play a Role in Age and Gender-Related Difference in Traumatic Brain Injury: Implications from Animal Studies. Front Neurol 2014; 5:161. [PMID: 25221540 PMCID: PMC4147999 DOI: 10.3389/fneur.2014.00161] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 08/12/2014] [Indexed: 11/23/2022] Open
Abstract
Inconsistent gender differences in the outcome of TBI have been reported. The mechanism is unknown. In a recent male animal study, repeated stress followed by TBI had synergistic effects on brain gene expression and caused greater behavioral deficits. Because females are more likely to develop anxiety after stress and because anxiety is mediated by cannabinoid receptors (CBRs) (CB1 and CB2), there is a need to compare CB1 and CB2 expression in stressed males and females. CB1 and CB2 mRNA expression was determined in the amygdala, hippocampus, prefrontal cortex (PFC), and hypothalamus of adolescent male and female rats after 3 days of repeated tail-shock stress using qPCR. PFC CB1 and CB2 protein levels were determined using Western blot techniques. Both gender and stress had significant effects on brain CB1 mRNA expression levels. Overall, females showed significantly higher CB1 and CB2 mRNA levels in all brain regions than males (p < 0.01). Repeated stress reduced CB1 mRNA levels in the amygdala, hippocampus, and PFC (p < 0.01, each). A gender × stress interaction was found in CB1 mRNA level in the hippocampus (p < 0.05), hypothalamus (p < 0.01), and PFC (p < 0.01). Within-sex one-way ANOVA analysis showed decreased CB1 mRNA in the hippocampus, hypothalamus, and PFC of stressed females (p < 0.01, each) but increased CB1 mRNA levels in the hypothalamus of stressed males (p < 01). There was a gender and stress interaction in prefrontal CB1 receptor protein levels (p < 0.05), which were decreased in stressed females only (p < 0.05). Prefrontal CB2 protein levels were decreased in both male and female animals after repeated stress (p < 0.05, each). High basal levels of CBR expression in young naïve females could protect against TBI damage whereas stress-induced CBR deficits could predict a poor outcome of TBI in repeatedly stressed females. Further animal studies could help evaluate this possibility.
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Affiliation(s)
- Guoqiang Xing
- Department of Psychiatry, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - Janis Carlton
- Department of Psychiatry, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - Xiaolong Jiang
- Department of Psychiatry, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - Jillian Wen
- Department of Psychiatry, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - Min Jia
- Department of Psychiatry, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
| | - He Li
- Department of Psychiatry, Uniformed Services University of the Health Sciences , Bethesda, MD , USA
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Abstract
We review recent work on the role of intrinsic amygdala networks in the regulation of classically conditioned defensive behaviors, commonly known as conditioned fear. These new developments highlight how conditioned fear depends on far more complex networks than initially envisioned. Indeed, multiple parallel inhibitory and excitatory circuits are differentially recruited during the expression versus extinction of conditioned fear. Moreover, shifts between expression and extinction circuits involve coordinated interactions with different regions of the medial prefrontal cortex. However, key areas of uncertainty remain, particularly with respect to the connectivity of the different cell types. Filling these gaps in our knowledge is important because much evidence indicates that human anxiety disorders results from an abnormal regulation of the networks supporting fear learning.
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Rea K, Olango WM, Okine BN, Madasu MK, McGuire IC, Coyle K, Harhen B, Roche M, Finn DP. Impaired endocannabinoid signalling in the rostral ventromedial medulla underpins genotype-dependent hyper-responsivity to noxious stimuli. Pain 2014; 155:69-79. [DOI: 10.1016/j.pain.2013.09.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 08/18/2013] [Accepted: 09/09/2013] [Indexed: 12/20/2022]
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Rimonabant precipitates anxiety in rats withdrawn from palatable food: role of the central amygdala. Neuropsychopharmacology 2013; 38:2498-507. [PMID: 23793355 PMCID: PMC3799070 DOI: 10.1038/npp.2013.153] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 06/15/2013] [Accepted: 06/17/2013] [Indexed: 01/03/2023]
Abstract
The anti-obesity medication rimonabant, an antagonist of cannabinoid type-1 (CB(1)) receptor, was withdrawn from the market because of adverse psychiatric side effects, including a negative affective state. We investigated whether rimonabant precipitates a negative emotional state in rats withdrawn from palatable food cycling. The effects of systemic administration of rimonabant on anxiety-like behavior, food intake, body weight, and adrenocortical activation were assessed in female rats during withdrawal from chronic palatable diet cycling. The levels of the endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG), and the CB(1) receptor mRNA and the protein in the central nucleus of the amygdala (CeA) were also investigated. Finally, the effects of microinfusion of rimonabant in the CeA on anxiety-like behavior, and food intake were assessed. Systemic administration of rimonabant precipitated anxiety-like behavior and anorexia of the regular chow diet in rats withdrawn from palatable diet cycling, independently from the degree of adrenocortical activation. These behavioral observations were accompanied by increased 2-AG, CB(1) receptor mRNA, and protein levels selectively in the CeA. Finally, rimonabant, microinfused directly into the CeA, precipitated anxiety-like behavior and anorexia. Our data show that (i) the 2-AG-CB(1) receptor system within the CeA is recruited during abstinence from palatable diet cycling as a compensatory mechanism to dampen anxiety, and (ii) rimonabant precipitates a negative emotional state by blocking the beneficial heightened 2-AG-CB(1) receptor signaling in this brain area. These findings help elucidate the link between compulsive eating and anxiety, and it will be valuable to develop better pharmacological treatments for eating disorders and obesity.
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Amygdala FAAH and anandamide: mediating protection and recovery from stress. Trends Pharmacol Sci 2013; 34:637-44. [PMID: 24325918 DOI: 10.1016/j.tips.2013.08.008] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 08/27/2013] [Accepted: 08/29/2013] [Indexed: 11/23/2022]
Abstract
A long-standing literature linking endocannabinoids (ECBs) to stress, fear, and anxiety has led to growing interest in developing novel anxiolytics targeting the ECB system. Following rapid on-demand biosynthesis and degradation upon neuronal activation, the ECB N-arachidonoylethanolamide (anandamide, AEA) is actively degraded by the serine hydrolase enzyme, fatty acid amide hydrolase (FAAH). Exposure to stress rapidly mobilizes FAAH to deplete the signaling pool of AEA and increase neuronal excitability in a key anxiety-mediating region--the basolateral amygdala (BLA). Gene deletion or pharmacological inhibition of FAAH prevents stress-induced reductions in AEA and associated increases in BLA dendritic hypertrophy and anxiety-like behavior. Additionally, inhibition of FAAH facilitates long-term fear extinction and rescues deficient fear extinction in rodent models by enhancing AEA-CB1 (cannabinoid type 1) receptor signaling and synaptic plasticity in the BLA. These preclinical findings propose restoring deficient BLA AEA levels by pharmacologically inhibiting FAAH as a mechanism to therapeutically mitigate the effects of traumatic stress.
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Olango W, Géranton S, Roche M, Hunt S, Finn D. Novel molecular correlates of endocannabinoid-mediated fear-conditioned analgesia in rats. Eur J Pain 2013; 18:182-91. [DOI: 10.1002/j.1532-2149.2013.00369.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2013] [Indexed: 11/12/2022]
Affiliation(s)
- W.M. Olango
- Pharmacology and Therapeutics; School of Medicine; National University of Ireland Galway; Ireland
- NCBES Neuroscience Cluster; National University of Ireland Galway; Ireland
- Centre for Pain Research; National University of Ireland Galway; Ireland
| | - S.M. Géranton
- Department of Cell and Developmental Biology; University College London; UK
| | - M. Roche
- Physiology; School of Medicine; National University of Ireland Galway; Ireland
- NCBES Neuroscience Cluster; National University of Ireland Galway; Ireland
- Centre for Pain Research; National University of Ireland Galway; Ireland
| | - S.P. Hunt
- Department of Cell and Developmental Biology; University College London; UK
| | - D.P. Finn
- Pharmacology and Therapeutics; School of Medicine; National University of Ireland Galway; Ireland
- NCBES Neuroscience Cluster; National University of Ireland Galway; Ireland
- Centre for Pain Research; National University of Ireland Galway; Ireland
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Involvement of cannabinoid receptors in the amygdala and prefrontal cortex of rats in fear learning, consolidation, retrieval and extinction. Behav Brain Res 2013; 250:274-84. [PMID: 23702112 DOI: 10.1016/j.bbr.2013.05.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 04/29/2013] [Accepted: 05/03/2013] [Indexed: 11/21/2022]
Abstract
Cannabinoid receptors 1 (CB1R) have been shown to be a crucial part of the neuromodulatory endocannabinoid system which is involved in emotional learning and memory. We here investigated in rats the role of CB1R in the basolateral amygdala (BLA) and medial prefrontal cortex (mPFC) in different phases of fear learning, memory and extinction. We used the fear potentiated startle paradigm to measure the effects of local microinfusion of the CB1R agonist WIN 55,212-2 (WIN) or the CB1R antagonist AM251 on acquisition, consolidation, retrieval and extinction of fear. No effects on fear acquisition of WIN or AM251 were found in the BLA or mPFC. WIN impaired fear retrieval in the BLA and in mPFC. Also, WIN reduced fear consolidation in the BLA but not in the mPFC. AM251 decreased fear consolidation after mPFC infusion. Likewise, fear extinction was impaired by AM251 infused into the mPFC. Our data indicate that fear memory consolidation and retrieval, as well as extinction are regulated differentially by amygdaloid and cortical CB1R.
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Evidence for a role of GABAergic and glutamatergic signalling in the basolateral amygdala in endocannabinoid-mediated fear-conditioned analgesia in rats. Pain 2013; 154:576-585. [DOI: 10.1016/j.pain.2012.12.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 08/25/2012] [Accepted: 12/20/2012] [Indexed: 12/17/2022]
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Smith KL, Ford GK, Jessop DS, Finn DP. Behavioural, neurochemical and neuroendocrine effects of the endogenous β-carboline harmane in fear-conditioned rats. J Psychopharmacol 2013; 27:162-70. [PMID: 23015542 DOI: 10.1177/0269881112460108] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The putative endogenous imidazoline binding site ligand harmane enhances neuronal activation in response to psychological stress and alters behaviour in animal models of anxiety and antidepressant efficacy. However, the neurobiological mechanisms underlying harmane's psychotropic effects are poorly understood. We investigated the effects of intraperitoneal injection of harmane (2.5 and 10 mg/kg) on fear-conditioned behaviour, hypothalamo-pituitary-adrenal axis activity, and monoaminergic activity within specific fear-associated areas of the rat brain. Harmane had no significant effect on the duration of contextually induced freezing or 22 kHz ultrasonic vocalisations and did not alter the contextually induced suppression of motor activity, including rearing. Harmane reduced the duration of rearing and tended to increase freezing in non-fear-conditioned controls, suggesting potential sedative effects. Harmane increased plasma ACTH and corticosterone concentrations, and serotonin (in hypothalamus, amygdaloid cortex, prefrontal cortex and hippocampus) and noradrenaline (prefrontal cortex) content, irrespective of fear-conditioning. Furthermore, harmane reduced dopamine and serotonin turnover in the PFC and hypothalamus, and serotonin turnover in the amygdaloid cortex in both fear-conditioned and non-fear-conditioned rats. In contrast, harmane increased dopamine and noradrenaline content and reduced dopamine turnover in the amygdala of fear-conditioned rats only, suggesting differential effects on catecholaminergic transmission in the presence and absence of fear. The precise mechanism(s) mediating these effects of harmane remain to be determined but may involve its inhibitory action on monoamine oxidases. These findings support a role for harmane as a neuromodulator, altering behaviour, brain neurochemistry and neuroendocrine function.
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Affiliation(s)
- Karen L Smith
- Pharmacology and Therapeutics, School of Medicine and NCBES Neuroscience Cluster, National University of Ireland, Galway, Ireland
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Varga B, Kassai F, Gyertyán I. Interactions of CB1 and mGlu5 receptor antagonists in food intake, anxiety and memory models in rats. Pharmacol Biochem Behav 2012; 103:425-30. [PMID: 23026059 DOI: 10.1016/j.pbb.2012.09.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 09/19/2012] [Accepted: 09/23/2012] [Indexed: 11/17/2022]
Abstract
CB(1) receptor antagonists proved to be effective anti-obesity drugs, however, their depressive and anxiogenic effects became also evident. Finding solution to overcome these psychiatric side effects is still in focus of research. Based on the available clinical and preclinical results we hypothesized that the combination of CB(1) and mGlu(5) receptor antagonisms may result in a pharmacological intervention, where the anxiolytic mGlu(5) receptor inhibition may counteract the anxiogenic psychiatric side effects of CB(1) antagonism, while CB(1) antagonism may ameliorate the memory impairing effect of mGlu(5) receptor antagonism. Further, the two components will synergistically interact in blocking food-intake and reducing obesity. For testing the interaction of mGlu(5) and CB(1) receptor antagonism MTEP [3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pridine; SIB-1757, 6-methyl-2-(phenylazo)-3-pyridinol)] (mGlu(5) antagonist) and rimonabant [(5-(4-Chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide)hydrochloride] (CB(1) antagonist) were used. All experiments were carried out in rats. Effects of the compounds on anxiety were tested in two foot shock induced ultrasonic vocalization paradigms, appetite suppression was assessed in the food intake test, while memory effects were tested in a context conditioned ultrasonic vocalization setup. MTEP abolished the anxiogenic effect of rimonabant, while there was an additive cooperation in suppressing appetite. However, rimonabant did not ameliorate the memory impairing effect of MTEP. By combination of CB(1) and mGluR5 antagonism, anxiety related side effects might be attenuated, appetite suppression maintained, nevertheless, the possible emergence of unwanted memory impairments can overshadow its therapeutic success.
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Affiliation(s)
- Balázs Varga
- Department of Behavioral Pharmacology, Gedeon Richter Plc., 1103 Budapest Gyömrői út 19-21, Hungary
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Huang ACW, Shyu BC, Hsiao S, Chen TC, He ABH. Neural substrates of fear conditioning, extinction, and spontaneous recovery in passive avoidance learning: a c-fos study in rats. Behav Brain Res 2012; 237:23-31. [PMID: 23018123 DOI: 10.1016/j.bbr.2012.09.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/10/2012] [Accepted: 09/14/2012] [Indexed: 10/27/2022]
Abstract
Extinguishing fear conditioning and preventing the return of fear are the goal in the treatment of anxiety disorders. However, the neural substrates that mediate fear conditioning, extinction, and spontaneous recovery (i.e., the return of fear) remain uncertain. We utilized the aversive passive avoidance learning paradigm and Fos-like immunoreactivity to elucidate this issue. Exception for naïve rats that did not receive any treatment served as the control group, the other rats were subjected to three sessions of context/footshock (0.5 mA, 2s) pairings followed by 12 extinction sessions (context-no footshock). After the last extinction test, these rats were assigned to one of three groups reflecting the number of resting days before the test session (context-no footshock): Day 8, Day 9, and Day 10 groups. Only the Day 10 group exhibited spontaneous recovery during the test session. Fos-like immunoreactivity associated with fear conditioning was seen in the amygdala and cingulate cortex area 1 (Cg1). The extinction of fear was seen to be related to Cg1, cingulate cortex area 2 (Cg2), piriform cortex (Pir), and entorhinal cortex (Ect). Spontaneous recovery was seen to be related to amygdala, Pir, and Ect. The present findings indicate that the brain substrates of fear acquisition, extinction and spontaneous recovery have different ensembles of brain activations. These differences suggest that different brain targets may be considered for fear extinction and for avoiding the return of fear in anxiety disorders.
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Haghparast A, Ghalandari-Shamami M, Hassanpour-Ezatti M. Blockade of D1/D2 dopamine receptors within the nucleus accumbens attenuated the antinociceptive effect of cannabinoid receptor agonist in the basolateral amygdala. Brain Res 2012; 1471:23-32. [DOI: 10.1016/j.brainres.2012.06.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/17/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
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Orsini CA, Maren S. Neural and cellular mechanisms of fear and extinction memory formation. Neurosci Biobehav Rev 2012; 36:1773-802. [PMID: 22230704 PMCID: PMC3345303 DOI: 10.1016/j.neubiorev.2011.12.014] [Citation(s) in RCA: 321] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Revised: 12/16/2011] [Accepted: 12/23/2011] [Indexed: 02/08/2023]
Abstract
Over the course of natural history, countless animal species have evolved adaptive behavioral systems to cope with dangerous situations and promote survival. Emotional memories are central to these defense systems because they are rapidly acquired and prepare organisms for future threat. Unfortunately, the persistence and intrusion of memories of fearful experiences are quite common and can lead to pathogenic conditions, such as anxiety and phobias. Over the course of the last 30 years, neuroscientists and psychologists alike have attempted to understand the mechanisms by which the brain encodes and maintains these aversive memories. Of equal interest, though, is the neurobiology of extinction memory formation as this may shape current therapeutic techniques. Here we review the extant literature on the neurobiology of fear and extinction memory formation, with a strong focus on the cellular and molecular mechanisms underlying these processes.
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Affiliation(s)
- Caitlin A. Orsini
- Department of Psychology, University of Michigan, Ann Arbor, MI, 48109-1043, USA
| | - Stephen Maren
- Department of Psychology, University of Michigan, Ann Arbor, MI, 48109-1043, USA
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, 48109-1043, USA
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Olango WM, Roche M, Ford GK, Harhen B, Finn DP. The endocannabinoid system in the rat dorsolateral periaqueductal grey mediates fear-conditioned analgesia and controls fear expression in the presence of nociceptive tone. Br J Pharmacol 2012; 165:2549-60. [PMID: 21564082 DOI: 10.1111/j.1476-5381.2011.01478.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Endocannabinoids in the midbrain periaqueductal grey (PAG) modulate nociception and unconditioned stress-induced analgesia; however, their role in fear-conditioned analgesia (FCA) has not been examined. The present study examined the role of the endocannabinoid system in the dorsolateral (dl) PAG in formalin-evoked nociceptive behaviour, conditioned fear and FCA in rats. EXPERIMENTAL APPROACH Rats received intra-dlPAG administration of the CB(1) receptor antagonist/inverse agonist rimonabant, or vehicle, before re-exposure to a context paired 24 h previously with foot shock. Formalin-evoked nociceptive behaviour and fear-related behaviours (freezing and 22 kHz ultrasonic vocalization) were assessed. In a separate cohort, levels of endocannabinoids [2-arachidonoyl glycerol (2-AG) and N-arachidonoyl ethanolamide (anandamide; AEA)] and the related N-acylethanolamines (NAEs) [N-palmitoyl ethanolamide (PEA) and N-oleoyl ethanolamide (OEA)] were measured in dlPAG tissue following re-exposure to conditioned context in the presence or absence of formalin-evoked nociceptive tone. KEY RESULTS Re-exposure of rats to the context previously associated with foot shock resulted in FCA. Intra-dlPAG administration of rimonabant significantly attenuated FCA and fear-related behaviours expressed in the presence of nociceptive tone. Conditioned fear without formalin-evoked nociceptive tone was associated with increased levels of 2-AG, AEA, PEA and OEA in the dlPAG. FCA was specifically associated with an increase in AEA levels in the dlPAG. CONCLUSIONS AND IMPLICATIONS Conditioned fear to context mobilises endocannabinoids and NAEs in the dlPAG. These data support a role for endocannabinoids in the dlPAG in mediating the potent suppression of pain responding which occurs during exposure to conditioned aversive contexts. LINKED ARTICLES This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7.
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Affiliation(s)
- W M Olango
- Pharmacology and Therapeutics Physiology, School of Medicine NCBES Neuroscience Cluster Centre for Pain Research, National University of Ireland, Galway, Ireland
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Rabinak CA, Angstadt M, Sripada CS, Abelson JL, Liberzon I, Milad MR, Phan KL. Cannabinoid facilitation of fear extinction memory recall in humans. Neuropharmacology 2012; 64:396-402. [PMID: 22796109 DOI: 10.1016/j.neuropharm.2012.06.063] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/27/2012] [Accepted: 06/28/2012] [Indexed: 10/28/2022]
Abstract
A first-line approach to treat anxiety disorders is exposure-based therapy, which relies on extinction processes such as repeatedly exposing the patient to stimuli (conditioned stimuli; CS) associated with the traumatic, fear-related memory. However, a significant number of patients fail to maintain their gains, partly attributed to the fact that this inhibitory learning and its maintenance is temporary and conditioned fear responses can return. Animal studies have shown that activation of the cannabinoid system during extinction learning enhances fear extinction and its retention. Specifically, CB1 receptor agonists, such as Δ9-tetrahydrocannibinol (THC), can facilitate extinction recall by preventing recovery of extinguished fear in rats. However, this phenomenon has not been investigated in humans. We conducted a study using a randomized, double-blind, placebo-controlled, between-subjects design, coupling a standard Pavlovian fear extinction paradigm and simultaneous skin conductance response (SCR) recording with an acute pharmacological challenge with oral dronabinol (synthetic THC) or placebo (PBO) 2 h prior to extinction learning in 29 healthy adult volunteers (THC = 14; PBO = 15) and tested extinction retention 24 h after extinction learning. Compared to subjects that received PBO, subjects that received THC showed low SCR to a previously extinguished CS when extinction memory recall was tested 24 h after extinction learning, suggesting that THC prevented the recovery of fear. These results provide the first evidence that pharmacological enhancement of extinction learning is feasible in humans using cannabinoid system modulators, which may thus warrant further development and clinical testing. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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John CS, Currie PJ. N-arachidonoyl-serotonin in the basolateral amygdala increases anxiolytic behavior in the elevated plus maze. Behav Brain Res 2012; 233:382-8. [PMID: 22633963 DOI: 10.1016/j.bbr.2012.05.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 05/08/2012] [Accepted: 05/14/2012] [Indexed: 12/19/2022]
Abstract
CB(1) receptors in the amygdala have been shown to mediate learned and unlearned anxiety states, however, the role of amygdalar TRPV1 receptors remains unclear. In the present study we investigated the potential anxiolytic action of intra-basolateral amygdala (BLA) infusion of N-arachidonoyl-serotonin (AA-5-HT), a dual blocker of the endocannabinoid-inactivating enzyme, fatty acid amide hydrolase (FAAH), and a TRPV1 antagonist. Varying doses of AA-5-HT (0-0.5 nmol) were administered into the BLA prior to elevated plus maze testing. AA-5-HT significantly increased both time spent and number of entries into the open arms. Next, to determine whether the anxiolytic effects were the result of blocking FAAH, TRPV1, or whether a combined action was required, rats were given intra-BLA infusions of either 0.25 nmol AA-5-HT, 1.0 nmol capsazepine (CZP, a TRPV1 antagonist), 0.01 μg URB597 (a selective FAAH inhibitor), or vehicle. Again, AA-5-HT increased the time spent in the open arms as well as the number of open arm entries. In contrast, CZP and URB597 did not reliably alter plus maze performance. We then investigated the effects of co-administration of CZP (1.0 or 10.0 nmol) and URB597 (0.01 or 0.1 μg). At lower doses, co-injections significantly increased both open arm entries as well as the time spent in the open arms, compared to vehicle or either compound alone. While co-administration of the higher doses had no significant effect when compared to either vehicle or CZP treatment, we did observe that open arm activity was elevated in rats receiving combined CZP-URB597 treatment compared to URB597 alone. Overall, our findings indicate that simultaneous FAAH activity and TRPV1 activation are important with respect to the expression of unconditioned fear as mediated within the BLA.
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Roche M, Johnston P, Mhuircheartaigh ON, Olango WM, Mackie K, Finn DP. Effects of intra-basolateral amygdala administration of rimonabant on nociceptive behaviour and neuronal activity in the presence or absence of contextual fear. Eur J Pain 2012; 14:487-95. [DOI: 10.1016/j.ejpain.2009.08.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Revised: 07/16/2009] [Accepted: 08/26/2009] [Indexed: 01/10/2023]
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Abstract
Evidence for the involvement of the endocannabinoid system (ECS) in anxiety and fear has been accumulated, providing leads for novel therapeutic approaches. In anxiety, a bidirectional influence of the ECS has been reported, whereby anxiolytic and anxiogenic responses have been obtained after both increases and decreases of the endocannabinoid tone. The recently developed genetic tools have revealed different but complementary roles for the cannabinoid type 1 (CB1) receptor on GABAergic and glutamatergic neuronal populations. This dual functionality, together with the plasticity of CB1 receptor expression, particularly on GABAergic neurons, as induced by stressful and rewarding experiences, gives the ECS a unique regulatory capacity for maintaining emotional homeostasis. However, the promiscuity of the endogenous ligands of the CB1 receptor complicates the interpretation of experimental data concerning ECS and anxiety. In fear memory paradigms, the ECS is mostly involved in the two opposing processes of reconsolidation and extinction of the fear memory. Whereas ECS activation deteriorates reconsolidation, proper extinction depends on intact CB1 receptor signalling. Thus, both for anxiety and fear memory processing, endocannabinoid signalling may ensure an appropriate reaction to stressful events. Therefore, the ECS can be considered as a regulatory buffer system for emotional responses.
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Affiliation(s)
- S Ruehle
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
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Butler RK, Ford GK, Hogan M, Roche M, Doyle KM, Kelly JP, Kendall DA, Chapman V, Finn DP. Fear-induced suppression of nociceptive behaviour and activation of Akt signalling in the rat periaqueductal grey: role of fatty acid amide hydrolase. J Psychopharmacol 2012; 26:83-91. [PMID: 21926424 DOI: 10.1177/0269881111413823] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The endocannabinoid system regulates nociception and aversion and mediates fear-conditioned analgesia (FCA). We investigated the effects of the fatty acid amide hydrolase (FAAH) inhibitor URB597, which inhibits the catabolism of the endocannabinoid anandamide and related N-acylethanolamines, on expression of FCA and fear and pain related behaviour per se in rats. We also examined associated alterations in the expression of the signal transduction molecule phospho-Akt in the periaqueductal grey (PAG) by immunoblotting. FCA was modelled by assessing formalin-evoked nociceptive behaviour in an arena previously paired with footshock. URB597 (0.3 mg/kg, i.p.) enhanced FCA and increased fear-related behaviour in formalin-treated rats. Conditioned fear per se in non-formalin-treated rats was associated with increased expression of phospho-Akt in the PAG. URB597 reduced the expression of fear-related behaviour in the early part of the trial, an effect that was accompanied by attenuation of the fear-induced increase in phospho-Akt expression in the PAG. Intra-plantar injection of formalin also reduced the fear-induced increase in phospho-Akt expression. These data provide evidence for a role of FAAH in FCA, fear responding in the presence or absence of nociceptive tone, and fear-evoked increases in PAG phospho-Akt expression. In addition, the results suggest that fear-evoked activation of Akt signalling in the PAG is abolished in the presence of nociceptive tone.
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Affiliation(s)
- Ryan K Butler
- Department of Pharmacology and Therapeutics, School of Medicine, NCBES Neuroscience Cluster and Centre for Pain Research, National University of Ireland, Galway, Ireland
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Moreira FA, Aguiar DC, Resstel LB, Lisboa SF, Campos AC, Gomes FV, Guimarães FS. Neuroanatomical substrates involved in cannabinoid modulation of defensive responses. J Psychopharmacol 2012; 26:40-55. [PMID: 21616976 DOI: 10.1177/0269881111400651] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Administration of Cannabis sativa derivatives causes anxiolytic or anxiogenic effects in humans and laboratory animals, depending on the specific compound and dosage used. In agreement with these findings, several studies in the last decade have indicated that the endocannabinoid system modulates neuronal activity in areas involved in defensive responses. The mechanisms of these effects, however, are still not clear. The present review summarizes recent data suggesting that they involve modulation of glutamate and GABA-mediated neurotransmission in brain sites such as the medial prefrontal cortex, amygdaloid complex, bed nucleus of the stria terminalis, hippocampus and dorsal periaqueductal gray. Moreover, we also discuss results indicating that, in these regions, the endocannabinoid system could be particularly engaged by highly stressful situations.
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Affiliation(s)
- F A Moreira
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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50
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Neurokinin-1 receptor deletion modulates behavioural and neurochemical alterations in an animal model of depression. Behav Brain Res 2011; 228:91-8. [PMID: 22155476 DOI: 10.1016/j.bbr.2011.11.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 11/21/2011] [Accepted: 11/26/2011] [Indexed: 12/28/2022]
Abstract
The substance P/NK1 receptor system plays an important role in the regulation of stress and emotional responding and as such had been implicated in the pathophysiology of anxiety and depression. The present study investigated whether alterations in the substance P/NK1 receptor system in brain areas which regulate emotional responding accompany the depressive behavioural phenotype observed in the olfactory bulbectomised (OB) mouse. The effect of NK1 receptor deletion on behavioural responding and monoamine levels in discrete brain regions of the OB model, were also examined. Substance P levels in the frontal cortex and NK1 receptor expression in the amygdala and hippocampus were enhanced following olfactory bulbectomy. Although NK1 receptor knockout (NK1-/-) mice did not exhibit altered behavioural responding in the open field test, noradrenaline levels were enhanced in the frontal cortex, amygdala and hippocampus, as were serotonin levels in the frontal cortex. Locomotor activity and exploratory behaviour were enhanced in wild type OB mice, indicative of a depressive-like phenotype, an effect attenuated in NK1-/- mice. Bulbectomy induced a decrease in noradrenaline and 5-HIAA in the frontal cortex and an increase in serotonin in the amygdala, effects attenuated in OB NK1-/- mice. The present studies indicate that alterations in substance P/NK1 receptor system underlie, at least in part, the behavioural and monoaminergic changes in this animal model of depression.
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