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Wei N, Guo Z, Qiu M, Ye R, Shao X, Liang Y, Liu B, Fang J, Fang J, Du J. Astrocyte Activation in the ACC Contributes to Comorbid Anxiety in Chronic Inflammatory Pain and Involves in The Excitation-Inhibition Imbalance. Mol Neurobiol 2024; 61:6934-6949. [PMID: 38363535 DOI: 10.1007/s12035-024-04027-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 02/06/2024] [Indexed: 02/17/2024]
Abstract
Neurons within the anterior cingulate cortex (ACC) orchestrate the co-occurrence of chronic pain and anxiety. The ACC hyperactivity plays a crucial role in the emotional impact of neuropathic pain. Astrocyte-mediated neuroinflammatory is responsible for regulating the balance between excitation-inhibition (E/I) in the brain. However, there is limited understanding of the possible contributions of astrocytes in the ACC to comorbidity of anxiety and chronic inflammatory pain. This paper aims to investigate the possible contribution of astrocytes in the ACC to the comorbidity between anxiety and chronic inflammatory pain, as well as their involvement in the E/I imbalance of pyramidal cells. Our results show that CFA rats displayed allodynia and anxiety-like behaviors. The E/I balance in the ACC shifts to excitement in comorbidity of chronic pain and anxiety by western blotting, and electrophysiological recording. Result of RNA-Seq also indicated that E/I imbalance and neuroinflammation of ACC were involved in pain-anxiety comorbidity. Then, positive cells of GFAP but not Iba1 in the contralateral ACC were increased; the mRNA expression of GFAP and its activation-related proinflammatory cytokines (TNF-α, IL-6, and IL-1β) in the contralateral ACC were also elevated. Furthermore, specific chemogenic inhibition of ACC astrocytes reversed comorbid pain and anxiety and suppressed high ACC excitability. Our data suggest that astrocytes participate in comorbid pain and anxiety and excitation-inhibition imbalance in ACC. Inhibition astrocyte activation can reduce anxiety related to pain and restore the imbalance in the ACC. These findings shed light on the involvement of astrocytes in comorbid conditions, offering valuable insights into a potential therapeutic approach for the co-occurrence of chronic pain and anxiety.
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Affiliation(s)
- Naixuan Wei
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
| | - Zi Guo
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
| | - Mengting Qiu
- Fuchun Community Health Service Center of Fuyang District, Hangzhou, 311400, China
| | - Ru Ye
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
| | - Xiaomei Shao
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
| | - Yi Liang
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
| | - Boyi Liu
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China
| | - Jianqiao Fang
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
| | - Junfan Fang
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
| | - Junying Du
- Department of Neurobiology and Acupuncture Research, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
- Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
- Key Laboratory for Research of Acupuncture Treatment and Transformation of Emotional Diseases, The Third School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
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Soto JS, Neupane C, Kaur M, Pandey V, Wohlschlegel JA, Khakh BS. Astrocyte Gi-GPCR signaling corrects compulsive-like grooming and anxiety-related behaviors in Sapap3 knockout mice. Neuron 2024:S0896-6273(24)00541-5. [PMID: 39163865 DOI: 10.1016/j.neuron.2024.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 05/06/2024] [Accepted: 07/23/2024] [Indexed: 08/22/2024]
Abstract
Astrocytes are morphologically complex cells that serve essential roles. They are widely implicated in central nervous system (CNS) disorders, with changes in astrocyte morphology and gene expression accompanying disease. In the Sapap3 knockout (KO) mouse model of compulsive and anxiety-related behaviors related to obsessive-compulsive disorder (OCD), striatal astrocytes display reduced morphology and altered actin cytoskeleton and Gi-G-protein-coupled receptor (Gi-GPCR) signaling proteins. Here, we show that normalizing striatal astrocyte morphology, actin cytoskeleton, and essential homeostatic support functions by targeting the astrocyte Gi-GPCR pathway using chemogenetics corrected phenotypes in Sapap3 KO mice, including anxiety-related and compulsive behaviors. Our data portend an astrocytic pharmacological strategy for rescuing phenotypes in brain disorders that include compromised astrocyte morphology and tissue support.
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Affiliation(s)
- Joselyn S Soto
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA.
| | - Chiranjivi Neupane
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Muskan Kaur
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Vijaya Pandey
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA.
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Sadrzadeh‐Afshar M, Salari B, shobeiri A, HafeziMotlagh K. Investigating the effect of obsessive-compulsive disorder on clinical symptoms of temporomandibular joint disorders. Clin Exp Dent Res 2023; 9:1191-1199. [PMID: 37840225 PMCID: PMC10728531 DOI: 10.1002/cre2.798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 10/02/2023] [Accepted: 10/05/2023] [Indexed: 10/17/2023] Open
Abstract
OBJECTIVES Temporomandibular disorders (TMD) are a group of clinical conditions involving muscles of mastication, temporomandibular joint (TMJ), and related structures or both. TMD is characterized by facial pain in TMJ and muscles of mastication, limitation or deviation of jaw movement, and TMJ sounds during jaw movement and function. The highest risk of TMD prevalence is between 18 and 24 years, and a relationship is between chronic TMD and psychological disorders such as stress and depression. The knowledge of the function of this joint and those with TMD symptoms when visiting the dentist will help to provide an ideal treatment plan for the patient. Therefore, if the therapist is familiar with the various etiological factors of this disorder, he will provide better treatment, especially if the simultaneous effect of psychological factors such as stress and obsessive-compulsive disorder (OCD) along with occlusal factors such as posterior cross-bite, overjet, and overbite is measured, it can be a valuable guide for clinicians. METHODS AND MATERIALS In this study, 385 patients were examined by DASS42 and Maudsley's test and classified into normal, with stress, and stress plus OCD groups. TMJ was examined for each of them by the TMD-RDC test. The presence or absence of TMD was noted in their file. RESULTS The prevalence of TMD was 20.7% in the normal group, 30.70% in the stress group, and 44.68% in the stress and OCD group. After analyzing the data by SPSS 24 and performing analysis of variance and Duncan tests, no significant difference was found between the probability of TMD in normal and stressed groups, but the stress and OCD group has a higher chance of TMD. CONCLUSION Although the co-occurrence of stress and OCD is associated with the prevalence of TMD, it cannot be considered a cause of TMD.
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Affiliation(s)
| | - Behzad Salari
- Orthodontics Department, Faculty of Dentistry, Tehran Medical SciencesIslamic Azad UniversityTehranIran
| | - Ali shobeiri
- Department of Oral and Maxillofacial Medicine, Faculty of DentistryAJA University of Medical SciencesTehranIran
| | - Kimia HafeziMotlagh
- Department of Oral Medicine, School of DentistryTehran University of Medical SciencesTehranIran
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Verkhratsky A, Butt A, Li B, Illes P, Zorec R, Semyanov A, Tang Y, Sofroniew MV. Astrocytes in human central nervous system diseases: a frontier for new therapies. Signal Transduct Target Ther 2023; 8:396. [PMID: 37828019 PMCID: PMC10570367 DOI: 10.1038/s41392-023-01628-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 08/15/2023] [Accepted: 08/22/2023] [Indexed: 10/14/2023] Open
Abstract
Astroglia are a broad class of neural parenchymal cells primarily dedicated to homoeostasis and defence of the central nervous system (CNS). Astroglia contribute to the pathophysiology of all neurological and neuropsychiatric disorders in ways that can be either beneficial or detrimental to disorder outcome. Pathophysiological changes in astroglia can be primary or secondary and can result in gain or loss of functions. Astroglia respond to external, non-cell autonomous signals associated with any form of CNS pathology by undergoing complex and variable changes in their structure, molecular expression, and function. In addition, internally driven, cell autonomous changes of astroglial innate properties can lead to CNS pathologies. Astroglial pathophysiology is complex, with different pathophysiological cell states and cell phenotypes that are context-specific and vary with disorder, disorder-stage, comorbidities, age, and sex. Here, we classify astroglial pathophysiology into (i) reactive astrogliosis, (ii) astroglial atrophy with loss of function, (iii) astroglial degeneration and death, and (iv) astrocytopathies characterised by aberrant forms that drive disease. We review astroglial pathophysiology across the spectrum of human CNS diseases and disorders, including neurotrauma, stroke, neuroinfection, autoimmune attack and epilepsy, as well as neurodevelopmental, neurodegenerative, metabolic and neuropsychiatric disorders. Characterising cellular and molecular mechanisms of astroglial pathophysiology represents a new frontier to identify novel therapeutic strategies.
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Affiliation(s)
- Alexei Verkhratsky
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China.
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania.
| | - Arthur Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Baoman Li
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
| | - Peter Illes
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04109, Leipzig, Germany
| | - Robert Zorec
- Celica Biomedical, Lab Cell Engineering, Technology Park, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Ljubljana, Slovenia
| | - Alexey Semyanov
- Department of Physiology, Jiaxing University College of Medicine, 314033, Jiaxing, China
| | - Yong Tang
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Key Laboratory of Acupuncture for Senile Disease (Chengdu University of TCM), Ministry of Education/Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China.
| | - Michael V Sofroniew
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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Wollina U, Fölster-Holst R, Karadağ AS. Miscellaneous annular diseases. Clin Dermatol 2023; 41:413-421. [PMID: 37453713 DOI: 10.1016/j.clindermatol.2023.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Annular lesions represent a unique macro-morphologic pattern in various skin disorders that may be found in pityriasis rotunda, elastosis perforans serpiginosa, subacute nodular migratory panniculitis, keratolysis exfoliativa, neutrophilic eccrine hidradenitis, hemophagocytic lymphohistiocytosis, and intentionally induced annular lesions. This group is highly heterogenous and variable in clinical presentation. Whereas some are benign self-limiting disorders like pityriasis rotunda, others such as hemophagocytic lymphohistiocytosis follow a chronic course or have a potential of being life-threatening. Epidemiology, pathogenesis, histopathology, clinical presentation and diagnosis, differential diagnosis, and treatment are discussed.
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Affiliation(s)
- Uwe Wollina
- Department of Dermatology and Allergology, Städtisches Klinikum Dresden, Academic Teaching Hospital, Dresden, Germany.
| | - Regina Fölster-Holst
- Department of Dermatology, Venereology and Allergology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Kruyer A, Kalivas PW, Scofield MD. Astrocyte regulation of synaptic signaling in psychiatric disorders. Neuropsychopharmacology 2023; 48:21-36. [PMID: 35577914 PMCID: PMC9700696 DOI: 10.1038/s41386-022-01338-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/27/2022] [Accepted: 05/01/2022] [Indexed: 02/07/2023]
Abstract
Over the last 15 years, the field of neuroscience has evolved toward recognizing the critical role of astroglia in shaping neuronal synaptic activity and along with the pre- and postsynapse is now considered an equal partner in tripartite synaptic transmission and plasticity. The relative youth of this recognition and a corresponding deficit in reagents and technologies for quantifying and manipulating astroglia relative to neurons continues to hamper advances in understanding tripartite synaptic physiology. Nonetheless, substantial advances have been made and are reviewed herein. We review the role of astroglia in synaptic function and regulation of behavior with an eye on how tripartite synapses figure into brain pathologies underlying behavioral impairments in psychiatric disorders, both from the perspective of measures in postmortem human brains and more subtle influences on tripartite synaptic regulation of behavior in animal models of psychiatric symptoms. Our goal is to provide the reader a well-referenced state-of-the-art understanding of current knowledge and predict what we may discover with deeper investigation of tripartite synapses using reagents and technologies not yet available.
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Affiliation(s)
- Anna Kruyer
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Peter W Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
- Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA.
| | - Michael D Scofield
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
- Department of Anesthesia & Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA.
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Kilb W, Kirischuk S. GABA Release from Astrocytes in Health and Disease. Int J Mol Sci 2022; 23:ijms232415859. [PMID: 36555501 PMCID: PMC9784789 DOI: 10.3390/ijms232415859] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/06/2022] [Accepted: 12/10/2022] [Indexed: 12/15/2022] Open
Abstract
Astrocytes are the most abundant glial cells in the central nervous system (CNS) mediating a variety of homeostatic functions, such as spatial K+ buffering or neurotransmitter reuptake. In addition, astrocytes are capable of releasing several biologically active substances, including glutamate and GABA. Astrocyte-mediated GABA release has been a matter of debate because the expression level of the main GABA synthesizing enzyme glutamate decarboxylase is quite low in astrocytes, suggesting that low intracellular GABA concentration ([GABA]i) might be insufficient to support a non-vesicular GABA release. However, recent studies demonstrated that, at least in some regions of the CNS, [GABA]i in astrocytes might reach several millimoles both under physiological and especially pathophysiological conditions, thereby enabling GABA release from astrocytes via GABA-permeable anion channels and/or via GABA transporters operating in reverse mode. In this review, we summarize experimental data supporting both forms of GABA release from astrocytes in health and disease, paying special attention to possible feedback mechanisms that might govern the fine-tuning of astrocytic GABA release and, in turn, the tonic GABAA receptor-mediated inhibition in the CNS.
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The Potential of N-Acetylcysteine for Treatment of Trichotillomania, Excoriation Disorder, Onychophagia, and Onychotillomania: An Updated Literature Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116370. [PMID: 35681955 PMCID: PMC9180086 DOI: 10.3390/ijerph19116370] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/21/2022] [Accepted: 05/22/2022] [Indexed: 02/01/2023]
Abstract
BACKGROUND Trichotillomania (TTM), excoriation disorder, onychophagia, and onychotillomania are categorized as body focused repetitive behavior (BFRB) disorders, causing damage to the skin, hair, and/or nails with clinically significant psychosocial consequences. Currently, there are no standardized treatments for these compulsive, self-induced disorders. Studies on treatment of these disorders using psychotropic drugs (i.e., selective serotonin reuptake inhibitors, tricyclic antidepressants, anticonvulsants) have shown variable efficacy. Recently, there is a growing interest in N-acetylcysteine (NAC) for treating BFRBs. NAC is a glutamate modulator that has shown promise in successfully reducing the compulsive behaviors in BFRB disorders. This article provides an updated review of the literature on the use of NAC in TTM, excoriation disorder, onychophagia, and onychotillomania. METHODS Relevant articles were searched in the PubMed/MEDLINE database. RESULTS Twenty-four clinical trials, retrospective cohort studies, and case reports assessing the efficacy of NAC in TTM, excoriation disorder, and onychophagia were included. No studies for onychotillomania were found in our search. CONCLUSIONS Although NAC has proven successful for treatment of BFRB disorders, data is derived from few clinical trials and case reports assessing small numbers of patients. Larger studies with longer durations are needed to fully establish the efficacy of NAC in these disorders.
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McGrath T, Baskerville R, Rogero M, Castell L. Emerging Evidence for the Widespread Role of Glutamatergic Dysfunction in Neuropsychiatric Diseases. Nutrients 2022; 14:nu14050917. [PMID: 35267893 PMCID: PMC8912368 DOI: 10.3390/nu14050917] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/06/2022] [Accepted: 02/15/2022] [Indexed: 02/04/2023] Open
Abstract
The monoamine model of depression has long formed the basis of drug development but fails to explain treatment resistance or associations with stress or inflammation. Recent animal research, clinical trials of ketamine (a glutamate receptor antagonist), neuroimaging research, and microbiome studies provide increasing evidence of glutamatergic dysfunction in depression and other disorders. Glutamatergic involvement across diverse neuropathologies including psychoses, neurodevelopmental, neurodegenerative conditions, and brain injury forms the rationale for this review. Glutamate is the brain's principal excitatory neurotransmitter (NT), a metabolic and synthesis substrate, and an immune mediator. These overlapping roles and multiple glutamate NT receptor types complicate research into glutamate neurotransmission. The glutamate microcircuit comprises excitatory glutamatergic neurons, astrocytes controlling synaptic space levels, through glutamate reuptake, and inhibitory GABA interneurons. Astroglia generate and respond to inflammatory mediators. Glutamatergic microcircuits also act at the brain/body interface via the microbiome, kynurenine pathway, and hypothalamus-pituitary-adrenal axis. Disruption of excitatory/inhibitory homeostasis causing neuro-excitotoxicity, with neuronal impairment, causes depression and cognition symptoms via limbic and prefrontal regions, respectively. Persistent dysfunction reduces neuronal plasticity and growth causing neuronal death and tissue atrophy in neurodegenerative diseases. A conceptual overview of brain glutamatergic activity and peripheral interfacing is presented, including the common mechanisms that diverse diseases share when glutamate homeostasis is disrupted.
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Affiliation(s)
- Thomas McGrath
- Green Templeton College, University of Oxford, Oxford OX2 6HG, UK; (T.M.); (L.C.)
| | - Richard Baskerville
- Faculty of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
- Correspondence:
| | - Marcelo Rogero
- School of Public Health, University of Sao Paulo, Sao Paulo 01246-904, Brazil;
| | - Linda Castell
- Green Templeton College, University of Oxford, Oxford OX2 6HG, UK; (T.M.); (L.C.)
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