101
|
The NMDA Receptor and Schizophrenia: From Pathophysiology to Treatment. ADVANCES IN PHARMACOLOGY 2016; 76:351-82. [PMID: 27288082 DOI: 10.1016/bs.apha.2016.01.006] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Schizophrenia is a severe mental illness that affects almost 1% of the population worldwide. Even though the etiology of schizophrenia is uncertain, it is believed to be a neurodevelopmental disorder that results from a combination of environmental insults and genetic vulnerabilities. Over the past 20 years, there has been a confluence of evidence from many research disciplines pointing to alterations in excitatory signaling, particularly involving hypofunction of the N-methyl-d-aspartate receptor (NMDAR), as a key contributor to the schizophrenia disease process. This review describes the structure-function relationship of the NMDAR channel and how the glycine modulatory site acts as an important regulator of its activity. In addition, this review highlights the genetic, pharmacologic, and biochemical evidence supporting the hypothesis that NMDAR hypofunction contributes to the pathophysiology of schizophrenia. Finally, this chapter highlights some of the most recent and promising pharmacological strategies that are designed to either, directly or indirectly, augment NMDAR function in an effort to treat the cognitive and negative symptoms of schizophrenia that are not helped by currently available medications.
Collapse
|
102
|
Abstract
Despite a lack of recent progress in the treatment of schizophrenia, our understanding of its genetic and environmental causes has considerably improved, and their relationship to aberrant patterns of neurodevelopment has become clearer. This raises the possibility that 'disease-modifying' strategies could alter the course to - and of - this debilitating disorder, rather than simply alleviating symptoms. A promising window for course-altering intervention is around the time of the first episode of psychosis, especially in young people at risk of transition to schizophrenia. Indeed, studies performed in both individuals at risk of developing schizophrenia and rodent models for schizophrenia suggest that pre-diagnostic pharmacotherapy and psychosocial or cognitive-behavioural interventions can delay or moderate the emergence of psychosis. Of particular interest are 'hybrid' strategies that both relieve presenting symptoms and reduce the risk of transition to schizophrenia or another psychiatric disorder. This Review aims to provide a broad-based consideration of the challenges and opportunities inherent in efforts to alter the course of schizophrenia.
Collapse
|
103
|
Woodberry KA, Shapiro DI, Bryant C, Seidman LJ. Progress and Future Directions in Research on the Psychosis Prodrome: A Review for Clinicians. Harv Rev Psychiatry 2016; 24:87-103. [PMID: 26954594 PMCID: PMC4870599 DOI: 10.1097/hrp.0000000000000109] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
LEARNING OBJECTIVES After participating in this activity, learners should be better able to: ABSTRACT The psychosis prodrome, or period of clinical and functional decline leading up to acute psychosis, offers a unique opportunity for identifying mechanisms of psychosis onset and for testing early-intervention strategies. We summarize major findings and emerging directions in prodromal research and provide recommendations for clinicians working with individuals suspected to be at high risk for psychosis. The past two decades of research have led to three major advances. First, tools and criteria have been developed that can reliably identify imminent risk for a psychotic disorder. Second, longitudinal clinical and psychobiological data from large multisite studies are strengthening individual risk assessment and offering insights into potential mechanisms of illness onset. Third, psychosocial and pharmacological interventions are demonstrating promise for delaying or preventing the onset of psychosis in help-seeking, high-risk individuals. The dynamic psychobiological processes implicated in both risk and onset of psychosis, including altered gene expression, cognitive dysfunction, inflammation, gray and white matter brain changes, and vulnerability-stress interactions suggest a wide range of potential treatment targets and strategies. The expansion of resources devoted to early intervention and prodromal research worldwide raises hope for investigating them. Future directions include identifying psychosis-specific risk and resilience factors in children, adolescents, and non-help-seeking community samples, improving study designs to test hypothesized mechanisms of change, and intervening with strategies that, in order to improve functional outcomes, better engage youth, address their environmental contexts, and focus on evidence-based neurodevelopmental targets. Prospective research on putatively prodromal samples has the potential to substantially reshape our understanding of mental illness and our efforts to combat it.
Collapse
Affiliation(s)
- Kristen A Woodberry
- From Harvard Medical School (Drs. Woodberry, Shapiro, and Seidman) and Beth Israel Deaconess Medical Center (Drs. Woodberry, Shapiro, and Seidman, and Ms. Bryant)
| | | | | | | |
Collapse
|
104
|
Sershen H, Hashim A, Dunlop DS, Suckow RF, Cooper TB, Javitt DC. Modulating NMDA Receptor Function with D-Amino Acid Oxidase Inhibitors: Understanding Functional Activity in PCP-Treated Mouse Model. Neurochem Res 2016; 41:398-408. [PMID: 26857796 DOI: 10.1007/s11064-016-1838-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 01/14/2016] [Accepted: 01/17/2016] [Indexed: 02/07/2023]
Abstract
Deficits in N-methyl-D-aspartate receptor (NMDAR) function are increasingly linked to persistent negative symptoms and cognitive deficits in schizophrenia. Accordingly, clinical studies have been targeting the modulatory site of the NMDA receptor, based on the decreased function of NMDA receptor, to see whether increasing NMDA function can potentially help treat the negative and cognitive deficits seen in the disease. Glycine and D-serine are endogenous ligands to the NMDA modulatory site, but since high doses are needed to affect brain levels, related compounds are being developed, for example glycine transport (GlyT) inhibitors to potentially elevate brain glycine or targeting enzymes, such as D-amino acid oxidase (DAAO) to slow the breakdown and increase the brain level of D-serine. In the present study we further evaluated the effect of DAAO inhibitors 5-chloro-benzo[d]isoxazol-3-ol (CBIO) and sodium benzoate (NaB) in a phencyclidine (PCP) rodent mouse model to see if the inhibitors affect PCP-induced locomotor activity, alter brain D-serine level, and thereby potentially enhance D-serine responses. D-Serine dose-dependently reduced the PCP-induced locomotor activity at doses above 1000 mg/kg. Acute CBIO (30 mg/kg) did not affect PCP-induced locomotor activity, but appeared to reduce locomotor activity when given with D-serine (600 mg/kg); a dose that by itself did not have an effect. However, the effect was also present when the vehicle (Trappsol(®)) was tested with D-serine, suggesting that the reduction in locomotor activity was not related to DAAO inhibition, but possibly reflected enhanced bioavailability of D-serine across the blood brain barrier related to the vehicle. With this acute dose of CBIO, D-serine level in brain and plasma were not increased. Another weaker DAAO inhibitor NaB (400 mg/kg), and NaB plus D-serine also significantly reduced PCP-induced locomotor activity, but without affecting plasma or brain D-serine level, arguing against a DAAO-mediated effect. However, NaB reduced plasma L-serine and based on reports that NaB also elevates various plasma metabolites, for example aminoisobutyric acid (AIB), a potential effect via the System A amino acid carrier may be involved in the regulation of synaptic glycine level to modulate NMDAR function needs to be investigated. Acute ascorbic acid (300 mg/kg) also inhibited PCP-induced locomotor activity, which was further attenuated in the presence of D-serine (600 mg/kg). Ascorbic acid may have an action at the dopamine membrane carrier and/or altering redox mechanisms that modulate NMDARs, but this needs to be further investigated. The findings support an effect of D-serine on PCP-induced hyperactivity. They also offer suggestions on an interaction of NaB via an unknown mechanism, other than DAAO inhibition, perhaps through metabolomic changes, and find unexpected synergy between D-serine and ascorbic acid that supports combined NMDA glycine- and redox-site intervention. Although mechanisms of these specific agents need to be determined, overall it supports continued glutamatergic drug development.
Collapse
Affiliation(s)
- Henry Sershen
- Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY, 10962, USA. .,NYU Langone Medical Center, Department of Psychiatry, New York, NY, 10016, USA.
| | - Audrey Hashim
- Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY, 10962, USA
| | - David S Dunlop
- Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY, 10962, USA
| | - Raymond F Suckow
- Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY, 10962, USA.,New York State Psychiatric Institute, 1051 Riverside Dr., New York, NY, 10032, USA
| | - Tom B Cooper
- Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY, 10962, USA.,New York State Psychiatric Institute, 1051 Riverside Dr., New York, NY, 10032, USA
| | - Daniel C Javitt
- Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY, 10962, USA. .,Columbia University College of Physicians and Surgeons, New York, NY, 10032, USA.
| |
Collapse
|
105
|
Hardingham GE, Do KQ. Linking early-life NMDAR hypofunction and oxidative stress in schizophrenia pathogenesis. Nat Rev Neurosci 2016; 17:125-34. [PMID: 26763624 DOI: 10.1038/nrn.2015.19] [Citation(s) in RCA: 231] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Molecular, genetic and pathological evidence suggests that deficits in GABAergic parvalbumin-positive interneurons contribute to schizophrenia pathophysiology through alterations in the brain's excitation-inhibition balance that result in impaired behaviour and cognition. Although the factors that trigger these deficits are diverse, there is increasing evidence that they converge on a common pathological hub that involves NMDA receptor hypofunction and oxidative stress. These factors have been separately linked to schizophrenia pathogenesis, but evidence now suggests that they are mechanistically interdependent and contribute to a common schizophrenia-associated pathology.
Collapse
Affiliation(s)
- Giles E Hardingham
- School of Biomedical Sciences, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - Kim Q Do
- Department of Psychiatry, Center of Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne, CH-1008, Prilly-Lausanne, Switzerland
| |
Collapse
|
106
|
N100 Repetition Suppression Indexes Neuroplastic Defects in Clinical High Risk and Psychotic Youth. Neural Plast 2016; 2016:4209831. [PMID: 26881109 PMCID: PMC4737454 DOI: 10.1155/2016/4209831] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/21/2015] [Accepted: 10/01/2015] [Indexed: 02/06/2023] Open
Abstract
Highly penetrant mutations leading to schizophrenia are enriched for genes coding for N-methyl-D-aspartate receptor signaling complex (NMDAR-SC), implicating plasticity defects in the disease's pathogenesis. The importance of plasticity in neurodevelopment implies a role for therapies that target these mechanisms in early life to prevent schizophrenia. Testing such therapies requires noninvasive methods that can assess engagement of target mechanisms. The auditory N100 is an obligatory cortical response whose amplitude decreases with tone repetition. This adaptation may index the health of plasticity mechanisms required for normal development. We exposed participants aged 5 to 17 years with psychosis (n = 22), at clinical high risk (CHR) for psychosis (n = 29), and healthy controls (n = 17) to an auditory tone repeated 450 times and measured N100 adaptation (mean amplitude during first 150 tones − mean amplitude during last 150 tones). N100 adaptation was reduced in CHR and psychosis, particularly among participants <13 years old. Initial N100 blunting partially accounted for differences. Decreased change in the N100 amplitude with tone repetition may be a useful marker of defects in neuroplastic mechanisms measurable early in life.
Collapse
|
107
|
Fan N, Luo Y, Xu K, Zhang M, Ke X, Huang X, Ding Y, Wang D, Ning Y, Deng X, He H. Relationship of serum levels of TNF-α, IL-6 and IL-18 and schizophrenia-like symptoms in chronic ketamine abusers. Schizophr Res 2015; 169:10-15. [PMID: 26589393 PMCID: PMC4888966 DOI: 10.1016/j.schres.2015.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 11/04/2015] [Accepted: 11/07/2015] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Exposing to NMDAR receptor antagonists, such as ketamine, produces schizophrenia-like symptoms in humans and deteriorates symptoms in schizophrenia patients. Meanwhile, schizophrenia is associated with alterations of cytokines in the immune system. This study aims to examine the serum TNF-α, IL-6 and IL-18 levels in chronic human ketamine users as compared to healthy subjects. The correlations between the serum cytokines levels with the demographic, ketamine use characteristics and psychiatric symptoms were also assessed. METHODS 155 subjects who fulfilled the criteria of ketamine dependence and 80 healthy control subjects were recruited. Serum TNF-α, IL-6 and IL-18 levels were measured using an enzyme-linked immunosorbent assay (ELISA). The psychiatric symptoms of the ketamine abusers were assessed using the Positive and Negative Syndrome Scale (PANSS). RESULTS Serum IL-6 and IL-18 levels were significantly higher, while serum TNF-α level was significantly lower among ketamine users than among healthy controls (p<0.05). Serum TNF-α levels showed a significant negative association with PANSS total score (r=-0.210, p<0.01) and negative subscore (r=-0.300, p<0.01). No significant association was found between PANSS score and serum levels of IL-6 and IL-18. CONCLUSIONS Serum levels of TNF-α, IL-6 and IL-18 were altered in chronic ketamine abusers which may play a role in schizophrenia-like symptoms in chronic ketamine abusers.
Collapse
Affiliation(s)
- Ni Fan
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China.
| | - Yayan Luo
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| | - Ke Xu
- Department of Psychiatry, Yale School of Medicine, 300 George St, New Haven, CT, USA
| | - Minling Zhang
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| | - Xiaoyin Ke
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China,Shenzhen Mental Health Center, 1080 Cuizhu Rd., Luohu District, Shenzhen, Guangdong 518020, China
| | - Xini Huang
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| | - Yi Ding
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| | - Daping Wang
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| | - Yuping Ning
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| | - Xuefeng Deng
- Guangzhou Baiyun Voluntary Drug Rehabilitation Hospital, 586 North of Baiyun Road, Baiyun District, Guangzhou, Guangdong 510440, China
| | - Hongbo He
- Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province 510370, China
| |
Collapse
|
108
|
Dong C, Hashimoto K. Early Intervention for Psychosis with N-Methyl-D-Aspartate Receptor Modulators. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE 2015; 13:328-9. [PMID: 26598597 PMCID: PMC4662175 DOI: 10.9758/cpn.2015.13.3.328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/07/2015] [Indexed: 11/18/2022]
Affiliation(s)
- Chao Dong
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| |
Collapse
|
109
|
Javitt DC, Sweet RA. Auditory dysfunction in schizophrenia: integrating clinical and basic features. Nat Rev Neurosci 2015; 16:535-50. [PMID: 26289573 PMCID: PMC4692466 DOI: 10.1038/nrn4002] [Citation(s) in RCA: 252] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Schizophrenia is a complex neuropsychiatric disorder that is associated with persistent psychosocial disability in affected individuals. Although studies of schizophrenia have traditionally focused on deficits in higher-order processes such as working memory and executive function, there is an increasing realization that, in this disorder, deficits can be found throughout the cortex and are manifest even at the level of early sensory processing. These deficits are highly amenable to translational investigation and represent potential novel targets for clinical intervention. Deficits, moreover, have been linked to specific structural abnormalities in post-mortem auditory cortex tissue from individuals with schizophrenia, providing unique insights into underlying pathophysiological mechanisms.
Collapse
Affiliation(s)
- Daniel C Javitt
- Division of Experimental Therapeutics, Departments of Psychiatry and Neuroscience, Columbia University College of Physicians and Surgeons, 1051 Riverside Drive, Unit 21, New York, New York 10032, USA
- Program in Cognitive Neuroscience and Schizophrenia, Nathan S. Kline Institute, 140 Old Orangeburg Rd, Orangeburg, New York 10962, USA
| | - Robert A Sweet
- Departments of Psychiatry and Neurology, University of Pittsburgh, 3811 O'Hara Street, Pittsburgh, Pennsylvania 15213, USA
- VISN 4 Mental Illness Research, Education and Clinical Center (MIRECC), VA Pittsburgh Healthcare System, Research Office Building (151R), University Drive C, Pittsburgh, Pennsylvania 15240, USA
| |
Collapse
|
110
|
|