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Chen X, Zhou YN, Lu XZ, Li RJ, Xiong YF, Sheng X, Zhu WW. Cognitive dysfunction in schizophrenia patients caused by down-regulation of γ-aminobutyric acid receptor subunits. World J Psychiatry 2024; 14:784-793. [DOI: 10.5498/wjp.v14.i6.784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/25/2024] [Accepted: 05/10/2024] [Indexed: 06/19/2024] Open
Abstract
BACKGROUND The expression pattern of gamma aminobutyric acid (GABA) receptor subunits are commonly altered in patients with schizophrenia, which may lead to nerve excitation/inhibition problems, affecting cognition, emotion, and behavior.
AIM To explore GABA receptor expression and its relationship with schizophrenia and to provide insights into more effective treatments.
METHODS This case-control study enrolled 126 patients with schizophrenia treated at our hospital and 126 healthy volunteers who underwent physical examinations at our hospital during the same period. The expression levels of the GABA receptor subunits were detected using 1H-magnetic resonance spectroscopy. The recognized cognitive battery tool, the MATRICS Consensus Cognitive Battery, was used to evaluate the scores for various dimensions of cognitive function. The correlation between GABA receptor subunit downregulation and schizophrenia was also analyzed.
RESULTS Significant differences in GABA receptor subunit levels were found between the case and control groups (P < 0.05). A significant difference was also found between the case and control groups in terms of cognitive function measures, including attention/alertness and learning ability (P < 0.05). Specifically, as the expression levels of GABRA1 (α1 subunit gene), GABRB2 (β2 subunit gene), GABRD (δ subunit), and GABRE (ε subunit) decreased, the severity of the patients’ condition increased gradually, indicating a positive correlation between the downregulation of these 4 receptor subunits and schizophrenia (P < 0.05). However, the expression levels of GABRA5 (α5 subunit gene) and GABRA6 (α6 subunit gene) showed no significant correlation with schizophrenia (P > 0.05).
CONCLUSION Downregulation of the GABA receptor subunits is positively correlated with schizophrenia. In other words, when GABA receptor subunits are downregulated in patients, cognitive impairment becomes more severe.
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Affiliation(s)
- Xi Chen
- Department of Child and Adolescent Psychiatric, Brain Hospital of Hunan Province, The Second People’s Hospital of Hunan Province, Changsha 410007, Hunan Province, China
| | - Ya-Nan Zhou
- Department of Child and Adolescent Psychiatric, Brain Hospital of Hunan Province, The Second People’s Hospital of Hunan Province, Changsha 410007, Hunan Province, China
| | - Xiao-Zi Lu
- Department of Psychiatry, Qingdao Mental Health Center, Qingdao 266034, Shandong Province, China
| | - Ren-Jiao Li
- Department of Child and Adolescent Psychiatric, Brain Hospital of Hunan Province, The Second People’s Hospital of Hunan Province, Changsha 410007, Hunan Province, China
| | - Yi-Fan Xiong
- Department of Psychiatry, Brain Hospital of Hunan Province, The Second People’s Hospital of Hunan Province, Changsha 410007, Hunan Province, China
| | - Xia Sheng
- Department of Child and Adolescent Psychiatric, Brain Hospital of Hunan Province, The Second People’s Hospital of Hunan Province, Changsha 410007, Hunan Province, China
| | - Wei-Wei Zhu
- Department of Sleep Disorders and Neurosis, Brain Hospital of Hunan Province, The Second People’s Hospital of Hunan Province, Changsha 410007, Hunan Province, China
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Zhong Y, Tubbs JD, Leung PBM, Zhan N, Hui TCK, Ho KKY, Hung KSY, Cheung EFC, So HC, Lui SSY, Sham PC. Whole-exome sequencing in a Chinese sample provides preliminary evidence for the link between rare/low-frequency immune-related variants and early-onset schizophrenia. Asian J Psychiatr 2024; 96:104046. [PMID: 38663229 DOI: 10.1016/j.ajp.2024.104046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 04/06/2024] [Indexed: 06/01/2024]
Abstract
Rare and low-frequency variants contribute to schizophrenia (SCZ), and may influence its age-at-onset (AAO). We examined the association of rare or low-frequency deleterious coding variants in Chinese patients with SCZ. We collected DNA samples in 197 patients with SCZ spectrum disorder and 82 healthy controls (HC), and performed exome sequencing. The AAO variable was ascertained in the majority of SCZ participants for identify the early-onset (EOS, AAO<=18) and adult-onset (AOS, AAO>18) subgroups. We examined the overall association of rare/low-frequency, damaging variants in SCZ versus HC, EOS versus HC, and AOS versus HC at the gene and gene-set levels using Sequence Kernel Association Test. The quantitative rare-variant association test of AAO was conducted. Resampling was used to obtain empirical p-values and to control for family-wise error rate (FWER). In binary-trait association tests, we identified 5 potential candidate risk genes and 10 gene ontology biological processes (GOBP) terms, among which PADI2 reached FWER-adjusted significance. In quantitative rare-variant association tests, we found marginally significant correlations of AAO with alterations in 4 candidate risk genes, and 5 GOBP pathways. Together, the biological and functional profiles of these genes and gene sets supported the involvement of perturbations of neural systems in SCZ, and altered immune functions in EOS.
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Affiliation(s)
- Yuanxin Zhong
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Justin D Tubbs
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China; Psychiatric and Neurodevelopmental Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Perry B M Leung
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China; Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Na Zhan
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Tomy C K Hui
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Karen K Y Ho
- Department of General Adult Psychiatry, Castle Peak Hospital, Hong Kong Special Administrative Region of China
| | - Karen S Y Hung
- Department of General Adult Psychiatry, Castle Peak Hospital, Hong Kong Special Administrative Region of China
| | - Eric F C Cheung
- Department of General Adult Psychiatry, Castle Peak Hospital, Hong Kong Special Administrative Region of China
| | - Hon-Cheong So
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region of China; Department of Psychiatry, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region of China.
| | - Simon S Y Lui
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China.
| | - Pak C Sham
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China; Centre for PanorOmic Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region of China; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region of China.
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3
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Howes OD, Bukala BR, Beck K. Schizophrenia: from neurochemistry to circuits, symptoms and treatments. Nat Rev Neurol 2024; 20:22-35. [PMID: 38110704 DOI: 10.1038/s41582-023-00904-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2023] [Indexed: 12/20/2023]
Abstract
Schizophrenia is a leading cause of global disability. Current pharmacotherapy for the disease predominantly uses one mechanism - dopamine D2 receptor blockade - but often shows limited efficacy and poor tolerability. These limitations highlight the need to better understand the aetiology of the disease to aid the development of alternative therapeutic approaches. Here, we review the latest meta-analyses and other findings on the neurobiology of prodromal, first-episode and chronic schizophrenia, and the link to psychotic symptoms, focusing on imaging evidence from people with the disorder. This evidence demonstrates regionally specific neurotransmitter alterations, including higher glutamate and dopamine measures in the basal ganglia, and lower glutamate, dopamine and γ-aminobutyric acid (GABA) levels in cortical regions, particularly the frontal cortex, relative to healthy individuals. We consider how dysfunction in cortico-thalamo-striatal-midbrain circuits might alter brain information processing to underlie psychotic symptoms. Finally, we discuss the implications of these findings for developing new, mechanistically based treatments and precision medicine for psychotic symptoms, as well as negative and cognitive symptoms.
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Affiliation(s)
- Oliver D Howes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
- Faculty of Medicine, Institute of Clinical Sciences, Imperial College London, London, UK.
| | - Bernard R Bukala
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Katherine Beck
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
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Petty A, Garcia-Hidalgo A, Halff EF, Natesan S, Withers DJ, Irvine EE, Kokkinou M, Wells LA, Bonsall DR, Tang SP, Veronese M, Howes OD. Sub-Chronic Ketamine Administration Increases Dopamine Synthesis Capacity in the Mouse Midbrain: a Preclinical In Vivo PET Study. Mol Imaging Biol 2023; 25:1054-1062. [PMID: 37872462 PMCID: PMC10728236 DOI: 10.1007/s11307-023-01865-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/26/2023] [Accepted: 10/05/2023] [Indexed: 10/25/2023]
Abstract
PURPOSE There is robust evidence that people with schizophrenia show elevated dopamine (DA) synthesis capacity in the striatum. This finding comes from positron emission tomography (PET) studies using radiolabelled l-3,4-dihydroxyphenylalanine (18F-DOPA). DA synthesis capacity also appears to be elevated in the midbrain of people with schizophrenia compared to healthy controls. We therefore aimed to optimise a method to quantify 18F-DOPA uptake in the midbrain of mice, and to utilise this method to quantify DA synthesis capacity in the midbrain of the sub-chronic ketamine model of schizophrenia-relevant hyperdopaminergia. PROCEDURES Adult male C57Bl6 mice were treated daily with either ketamine (30 mg/kg, i.p.) or vehicle (saline) for 5 days. On day 7, animals were administered 18F-DOPA (i.p.) and scanned in an Inveon PET/CT scanner. Data from the saline-treated group were used to optimise an atlas-based template to position the midbrain region of interest and to determine the analysis parameters which resulted in the greatest intra-group consistency. These parameters were then used to compare midbrain DA synthesis capacity (KiMod) between ketamine- and saline-treated animals. RESULTS Using an atlas-based template to position the 3.7 mm3 midbrain ROI with a T*-Tend window of 15-140 min to estimate KiMod resulted in the lowest intra-group variability and moderate test-retest agreement. Using these parameters, we found that KiMod was elevated in the midbrain of ketamine-treated animals in comparison to saline-treated animals (t(22) = 2.19, p = 0.048). A positive correlation between DA synthesis capacity in the striatum and the midbrain was also evident in the saline-treated animals (r2 = 0.59, p = 0.005) but was absent in ketamine-treated animals (r2 = 0.004, p = 0.83). CONCLUSIONS Using this optimised method for quantifying 18F-DOPA uptake in the midbrain, we found that elevated striatal DA synthesis capacity in the sub-chronic ketamine model extends to the midbrain. Interestingly, the dysconnectivity between the midbrain and striatum seen in this model is also evident in the clinical population. This model may therefore be ideal for assessing novel compounds which are designed to modulate pre-synaptic DA synthesis capacity.
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Affiliation(s)
- Alice Petty
- Faculty of Medicine, Imperial College London, Institute of Clinical Sciences, London, UK.
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, London, UK.
| | - Anna Garcia-Hidalgo
- Faculty of Medicine, Imperial College London, Institute of Clinical Sciences, London, UK
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, London, UK
| | - Els F Halff
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, London, UK
- King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK
| | - Sridhar Natesan
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, London, UK
- King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK
| | - Dominic J Withers
- Faculty of Medicine, Imperial College London, Institute of Clinical Sciences, London, UK
- Metabolic Signalling Group, MRC London Institute of Medical Sciences, London, UK
| | - Elaine E Irvine
- Faculty of Medicine, Imperial College London, Institute of Clinical Sciences, London, UK
- Metabolic Signalling Group, MRC London Institute of Medical Sciences, London, UK
| | - Michelle Kokkinou
- Faculty of Medicine, Imperial College London, Institute of Clinical Sciences, London, UK
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, London, UK
| | - Lisa A Wells
- Invicro, Burlington Danes, Hammersmith Hospital, London, UK
| | | | - Sac-Pham Tang
- Invicro, Burlington Danes, Hammersmith Hospital, London, UK
| | - Mattia Veronese
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- Department of Information Engineering, University of Padua, Padua, Italy
| | - Oliver D Howes
- Faculty of Medicine, Imperial College London, Institute of Clinical Sciences, London, UK
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, London, UK
- King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK
- South London and Maudsley NHS Foundation Trust, Camberwell, London, UK
- H. Lundbeck A/S, St Albans, AL1 2PS, UK
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Blaess S, Krabbe S. Cell type specificity for circuit output in the midbrain dopaminergic system. Curr Opin Neurobiol 2023; 83:102811. [PMID: 37972537 DOI: 10.1016/j.conb.2023.102811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 09/14/2023] [Accepted: 10/19/2023] [Indexed: 11/19/2023]
Abstract
Midbrain dopaminergic neurons are a relatively small group of neurons in the mammalian brain controlling a wide range of behaviors. In recent years, increasingly sophisticated tracing, imaging, transcriptomic, and machine learning approaches have provided substantial insights into the anatomical, molecular, and functional heterogeneity of dopaminergic neurons. Despite this wealth of new knowledge, it remains unclear whether and how the diverse features defining dopaminergic subclasses converge to delineate functional ensembles within the dopaminergic system. Here, we review recent studies investigating various aspects of dopaminergic heterogeneity and discuss how development, behavior, and disease influence subtype characteristics. We then outline what further approaches could be pursued to gain a more inclusive picture of dopaminergic diversity, which could be crucial to understanding the functional architecture of this system.
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Affiliation(s)
- Sandra Blaess
- Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
| | - Sabine Krabbe
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany.
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Zhong Y, Tubbs JD, Leung PBM, Zhan N, Hui TCK, Ho KKY, Hung KSY, Cheung EFC, So HC, Lui SSY, Sham PC. Early-onset schizophrenia is associated with immune-related rare variants in a Chinese sample. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.11.21.23298115. [PMID: 38045317 PMCID: PMC10690336 DOI: 10.1101/2023.11.21.23298115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Background Rare variants are likely to contribute to schizophrenia (SCZ), given the large discrepancy between the heritability estimated from twin and GWAS studies. Furthermore, the nature of the rare-variant contribution to SCZ may vary with the "age-at-onset" (AAO), since early-onset has been suggested as being indicative of neurodevelopment deviance. Objective To examine the association of rare deleterious coding variants in early- and adult-onset SCZ in a Chinese sample. Method Exome sequencing was performed on DNA from 197 patients with SCZ spectrum disorder and 82 healthy controls (HC) of Chinese ancestry recruited in Hong Kong. We also gathered AAO information in the majority of SCZ samples. Patients were classified into early-onset (EOS, AAO<18) and adult-onset (AOS, AAO>18). We collapsed the rare variants to improve statistical power and examined the overall association of rare variants in SCZ versus HC, EOS versus HC, and AOS versus HC at the gene and gene-set levels by Sequence Kernel Association Test. The quantitative rare-variant association test of AAO was also conducted. We focused on variants which were predicted to have a medium or high impact on the protein-encoding process as defined by Ensembl. We applied a 100000-time permutation test to obtain empirical p-values, with significance threshold set at p < 1e -3 to control family-wise error rates. Moreover, we compared the burden of targeted rare variants in significant risk genes and gene sets in cases and controls. Results Based on several binary-trait association tests (i.e., SCZ vs HC, EOS vs HC and AOS vs HC), we identified 7 candidate risk genes and 20 gene ontology biological processes (GOBP) terms, which exhibited higher burdens in SCZ than in controls. Based on quantitative rare-variant association tests, we found that alterations in 5 candidate risk genes and 7 GOBP pathways were significantly correlated with AAO. Based on biological and functional profiles of the candidate risk genes and gene sets, our findings suggested that, in addition to the involvement of perturbations in neural systems in SCZ in general, altered immune responses may be specifically implicated in EOS. Conclusion Disrupted immune responses may exacerbate abnormal perturbations during neurodevelopment and trigger the early onset of SCZ. We provided evidence of rare variants increasing SCZ risk in the Chinese population.
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Vinnakota C, Hudson MR, Jones NC, Sundram S, Hill RA. Potential Roles for the GluN2D NMDA Receptor Subunit in Schizophrenia. Int J Mol Sci 2023; 24:11835. [PMID: 37511595 PMCID: PMC10380280 DOI: 10.3390/ijms241411835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/19/2023] [Accepted: 07/22/2023] [Indexed: 07/30/2023] Open
Abstract
Glutamate N-methyl-D-aspartate receptor (NMDAR) hypofunction has been proposed to underlie schizophrenia symptoms. This theory arose from the observation that administration of NMDAR antagonists, which are compounds that inhibit NMDAR activity, reproduces behavioural and molecular schizophrenia-like phenotypes, including hallucinations, delusions and cognitive impairments in healthy humans and animal models. However, the role of specific NMDAR subunits in these schizophrenia-relevant phenotypes is largely unknown. Mounting evidence implicates the GluN2D subunit of NMDAR in some of these symptoms and pathology. Firstly, genetic and post-mortem studies show changes in the GluN2D subunit in people with schizophrenia. Secondly, the psychosis-inducing effects of NMDAR antagonists are blunted in GluN2D-knockout mice, suggesting that the GluN2D subunit mediates NMDAR-antagonist-induced psychotomimetic effects. Thirdly, in the mature brain, the GluN2D subunit is relatively enriched in parvalbumin (PV)-containing interneurons, a cell type hypothesized to underlie the cognitive symptoms of schizophrenia. Lastly, the GluN2D subunit is widely and abundantly expressed early in development, which could be of importance considering schizophrenia is a disorder that has its origins in early neurodevelopment. The limitations of currently available therapies warrant further research into novel therapeutic targets such as the GluN2D subunit, which may help us better understand underlying disease mechanisms and develop novel and more effective treatment options.
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Affiliation(s)
- Chitra Vinnakota
- Department of Psychiatry, School of Clinical Sciences, Faculty of Medical, Nursing and Health Sciences, Monash University, Clayton, VIC 3168, Australia
| | - Matthew R Hudson
- Department of Neuroscience, Faculty of Medical, Nursing and Health Sciences, Monash University, Melbourne, VIC 3004, Australia
| | - Nigel C Jones
- Department of Neuroscience, Faculty of Medical, Nursing and Health Sciences, Monash University, Melbourne, VIC 3004, Australia
| | - Suresh Sundram
- Department of Psychiatry, School of Clinical Sciences, Faculty of Medical, Nursing and Health Sciences, Monash University, Clayton, VIC 3168, Australia
- Mental Health Program, Monash Health, Clayton, VIC 3168, Australia
| | - Rachel A Hill
- Department of Psychiatry, School of Clinical Sciences, Faculty of Medical, Nursing and Health Sciences, Monash University, Clayton, VIC 3168, Australia
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