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Khan AQ, Thielen L, Le Pen G, Krebs MO, Kebir O, Groh A, Deest M, Bleich S, Frieling H, Jahn K. Methylation pattern and mRNA expression of synapse-relevant genes in the MAM model of schizophrenia in the time-course of adolescence. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2022; 8:110. [PMID: 36481661 PMCID: PMC9732294 DOI: 10.1038/s41537-022-00319-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 11/16/2022] [Indexed: 12/13/2022]
Abstract
Schizophrenia is highly heritable and aggregating in families, but genetics alone does not exclusively explain the pathogenesis. Many risk factors, including childhood trauma, viral infections, migration, and the use of cannabis, are associated with schizophrenia. Adolescence seems to be the critical period where symptoms of the disease manifest. This work focuses on studying an epigenetic regulatory mechanism (the role of DNA methylation) and its interaction with mRNA expression during development, with a particular emphasis on adolescence. The presumptions regarding the role of aberrant neurodevelopment in schizophrenia were tested in the Methyl-Azoxy-Methanol (MAM) animal model. MAM treatment induces neurodevelopmental disruptions and behavioral deficits in off-springs of the treated animals reminiscent of those observed in schizophrenia and is thus considered a promising model for studying this pathology. On a gestational day-17, adult pregnant rats were treated with the antimitotic agent MAM. Experimental animals were divided into groups and subgroups according to substance treatment (MAM and vehicle agent [Sham]) and age of analysis (pre-adolescent and post-adolescent). Methylation and mRNA expression analysis of four candidate genes, which are often implicated in schizophrenia, with special emphasis on the Dopamine hypothesis i.e., Dopamine receptor D2 (Drd2), and the "co-factors" Disrupted in schizophrenia 1 (DISC1), Synaptophysin (Syp), and Dystrobrevin-binding protein 1 (Dtnbp1), was performed in the Gyrus cingulum (CING) and prefrontal cortex (PFC). Data were analyzed to observe the effect of substance treatment between groups and the impact of adolescence within-group. We found reduced pre-adolescent expression levels of Drd2 in both brain areas under the application of MAM. The "co-factor genes" did not show high deviations in mRNA expression levels but high alterations of methylation rates under the application of MAM (up to ~20%), which diminished in the further time course, reaching a comparable level like in Sham control animals after adolescence. The pre-adolescent reduction in DRD2 expression might be interpreted as downregulation of the receptor due to hyperdopaminergic signaling from the ventral tegmental area (VTA), eventually even to both investigated brain regions. The notable alterations of methylation rates in the three analyzed co-factor genes might be interpreted as attempt to compensate for the altered dopaminergic neurotransmission.
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Affiliation(s)
- Abdul Qayyum Khan
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany ,grid.444940.9University of Management and Technology—School of Pharmacy, 72-A Raiwind Rd, Dubai Town, Lahore Pakistan
| | - Lukas Thielen
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Gwenaëlle Le Pen
- grid.512035.0Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Pathophysiology of Psychiatric disorders: Development and Vulnerability, U1266, 102-108 Rue de la Santé, 75014 Paris, France
| | - Marie-Odile Krebs
- grid.512035.0Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Pathophysiology of Psychiatric disorders: Development and Vulnerability, U1266, 102-108 Rue de la Santé, 75014 Paris, France ,GHU Paris Psychiatrie et Neurosciences, 1 Rue Cabanis, 75014 Paris, France
| | - Oussama Kebir
- grid.512035.0Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM, Pathophysiology of Psychiatric disorders: Development and Vulnerability, U1266, 102-108 Rue de la Santé, 75014 Paris, France ,GHU Paris Psychiatrie et Neurosciences, 1 Rue Cabanis, 75014 Paris, France
| | - Adrian Groh
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Maximilian Deest
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Stefan Bleich
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Helge Frieling
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Kirsten Jahn
- grid.10423.340000 0000 9529 9877Laboratory for Molecular Neurosciences (LMN), Department of Psychiatry, Social Psychiatry and Psychotherapy, Medical School Hannover (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Hatzipantelis C, Langiu M, Vandekolk TH, Pierce TL, Nithianantharajah J, Stewart GD, Langmead CJ. Translation-Focused Approaches to GPCR Drug Discovery for Cognitive Impairments Associated with Schizophrenia. ACS Pharmacol Transl Sci 2020; 3:1042-1062. [PMID: 33344888 PMCID: PMC7737210 DOI: 10.1021/acsptsci.0c00117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Indexed: 01/07/2023]
Abstract
There are no effective therapeutics for cognitive impairments associated with schizophrenia (CIAS), which includes deficits in executive functions (working memory and cognitive flexibility) and episodic memory. Compounds that have entered clinical trials are inadequate in terms of efficacy and/or tolerability, highlighting a clear translational bottleneck and a need for a cohesive preclinical drug development strategy. In this review we propose hippocampal-prefrontal-cortical (HPC-PFC) circuitry underlying CIAS-relevant cognitive processes across mammalian species as a target source to guide the translation-focused discovery and development of novel, procognitive agents. We highlight several G protein-coupled receptors (GPCRs) enriched within HPC-PFC circuitry as therapeutic targets of interest, including noncanonical approaches (biased agonism and allosteric modulation) to conventional clinical targets, such as dopamine and muscarinic acetylcholine receptors, along with prospective novel targets, including the orphan receptors GPR52 and GPR139. We also describe the translational limitations of popular preclinical cognition tests and suggest touchscreen-based assays that probe cognitive functions reliant on HPC-PFC circuitry and reflect tests used in the clinic, as tests of greater translational relevance. Combining pharmacological and behavioral testing strategies based in HPC-PFC circuit function creates a cohesive, translation-focused approach to preclinical drug development that may improve the translational bottleneck currently hindering the development of treatments for CIAS.
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Affiliation(s)
- Cassandra
J. Hatzipantelis
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Monica Langiu
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Teresa H. Vandekolk
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Tracie L. Pierce
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Jess Nithianantharajah
- Florey
Institute of Neuroscience
and Mental Health, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Gregory D. Stewart
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Christopher J. Langmead
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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D'Angelo A, Ceccanti M, Petrella C, Greco A, Tirassa P, Rosso P, Ralli M, Ferraguti G, Fiore M, Messina MP. Role of neurotrophins in pregnancy, delivery and postpartum. Eur J Obstet Gynecol Reprod Biol 2020; 247:32-41. [PMID: 32058187 DOI: 10.1016/j.ejogrb.2020.01.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 01/24/2020] [Accepted: 01/29/2020] [Indexed: 01/09/2023]
Abstract
Neurotrophins (NTs) are a family of polypeptides whose functions have been extensively studied in the past two decades. In particular, Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF) play a major role in the development, nutrition and growth of the central and peripheral nervous system and in the pathogenesis of neurodegenerative, cardiometabolic and (auto)immune diseases. However, NGF and BDNF have subtle functions for follicular development, implantation, and placentation. This short narrative review summarizes the existing evidence, published between 2000 and 2019, about the role of NTs in many different conditions that might affect women during and after pregnancy such as preeclampsia, gestational diabetes, obesity, depression, anxiety, smoking and alcohol abuse. Literature suggests that the dysregulation of synthesis and release of NTs may lead to decisive effects on both maternal and fetal health. Some piece of evidences was found about a possible association between NGF/BDNF and breastfeeding. Additional studies on human models are necessary to further characterize the role of NTs in life-changing experiences like labor and delivery.
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Affiliation(s)
- Alessio D'Angelo
- Department of Gynecology, Obstetric, and Urology, Sapienza University of Rome, Italy
| | - Mauro Ceccanti
- Centro Riferimento Alcologico Regione Lazio, Sapienza University of Rome, Italy
| | - Carla Petrella
- Institute of Biochemistry and Cell Biology, IBBC-CNR, Rome, Italy
| | - Antonio Greco
- Department of Sense Organs, Sapienza University of Rome, Italy
| | - Paola Tirassa
- Institute of Biochemistry and Cell Biology, IBBC-CNR, Rome, Italy
| | - Pamela Rosso
- Institute of Biochemistry and Cell Biology, IBBC-CNR, Rome, Italy
| | - Massimo Ralli
- Department of Sense Organs, Sapienza University of Rome, Italy
| | | | - Marco Fiore
- Institute of Biochemistry and Cell Biology, IBBC-CNR, Rome, Italy.
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Huo C, Liu X, Zhao J, Zhao T, Huang H, Ye H. Abnormalities in behaviour, histology and prefrontal cortical gene expression profiles relevant to schizophrenia in embryonic day 17 MAM-Exposed C57BL/6 mice. Neuropharmacology 2018; 140:287-301. [PMID: 30056124 DOI: 10.1016/j.neuropharm.2018.07.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 06/20/2018] [Accepted: 07/25/2018] [Indexed: 01/05/2023]
Abstract
Gestational and perinatal disruption of neural development increases the risk of developing schizophrenia (SCZ) later in life. Embryonic day 17 (E17) methylazoxymethanol (MAM) treatment leads to histological, physiological and behavioural abnormalities in post-puberty rats that model the neuropathological and cognitive deficits reported in SCZ patients. However, the validity of E17 MAM-exposed mice to model SCZ has not been explored. Here we treated E17 C57BL/6 mouse dams with various dosages of MAM. We found that this mouse strain was more vulnerable to MAM treatment than rats and there were gender differences in behavioural abnormalities, histological changes and prefrontal cortical gene expression profiles in MAM (7.5 mg/kg)-exposed mice. Both male and female MAM-exposed mice had deficits in prepulse inhibition. Female MAM-exposed mice exhibited mildly increased spontaneous locomotion activity and social recognition deficits, while male mice were normal. Consistently, only female MAM-exposed mice exhibited reduced brain weight, decreased size of prefrontal cortex (PFC) and enlarged lateral ventricles. Transcriptome analysis of the PFC revealed that there were more differentially expressed genes in female MAM-exposed mice than those in male mice. Moreover, expression of Pvalb, Arc and genes in their association networks were downregulated in the PFC of female MAM-exposed mice. These results indicate that E17 MAM-exposure in C57BL/6 mice leads to behavioural changes that model certain deficits reported in SCZ patients. MAM-exposed female mice may be used to study gene expression changes, inhibitory neural circuit dysfunction and glutamatergic synaptic plasticity deficits with a possible relation to those in the brains of SCZ patients.
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Affiliation(s)
- Chunyue Huo
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China; Yanjing Medical College, Capital Medical University, Beijing 100069, China
| | - Xu Liu
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China; Beijing Institute for Brain Disorders, Center of Schizophrenia, Capital Medical University, Beijing 100069, China
| | - Jialu Zhao
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China; Beijing Institute for Brain Disorders, Center of Schizophrenia, Capital Medical University, Beijing 100069, China
| | - Tian Zhao
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China; Beijing Institute for Brain Disorders, Center of Schizophrenia, Capital Medical University, Beijing 100069, China
| | - Huiling Huang
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China; Beijing Institute for Brain Disorders, Center of Schizophrenia, Capital Medical University, Beijing 100069, China
| | - Haihong Ye
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China; Beijing Institute for Brain Disorders, Center of Schizophrenia, Capital Medical University, Beijing 100069, China.
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5
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Kleven GA, Bellinger SA. Developmental pathways of motor dysfunction. Dev Psychobiol 2015; 57:435-46. [DOI: 10.1002/dev.21304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 02/24/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Gale A. Kleven
- Department of Psychology; Wright State University; Dayton OH 45435
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6
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Keeley RJ, Burger DK, Saucier DM, Iwaniuk AN. The size of non-hippocampal brain regions varies by season and sex in Richardson's ground squirrel. Neuroscience 2015; 289:194-206. [PMID: 25595988 DOI: 10.1016/j.neuroscience.2014.12.077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/29/2014] [Accepted: 12/18/2014] [Indexed: 11/19/2022]
Abstract
Sex- and season-specific modulation of hippocampal size and function is observed across multiple species, including rodents. Other non-hippocampal-dependent behaviors exhibit season and sex differences, and whether the associated brain regions exhibit similar variation with sex and season remains to be fully characterized. As such, we examined the brains of wild-caught Richardson's ground squirrels (RGS; Urocitellus richardsonii) for seasonal (breeding, non-breeding) and sex differences in the volumes of specific brain areas, including: total brain volume, corpus callosum (CC), anterior commissure (AC), medial prefrontal cortex (mPFC), total neocortex (NC), entorhinal cortex (EC), and superior colliculus (SC). Analyses of variance and covariance revealed significant interactions between season and sex for almost all areas studied, primarily resulting from females captured during the breeding season exhibiting larger volumes than females captured during the non-breeding season. This was observed for volumes of the AC, mPFC, NC, EC, and SC. Where simple main effects of season were observed for males (the NC and the SC), the volume advantage favoured males captured during the NBr season. Only two simple main effects of sex were observed: males captured in the non-breeding season had significantly larger total brain volume than females captured in the non-breeding season, and females captured during the breeding season had larger volumes of the mPFC and EC than males captured in the breeding season. These results indicate that females have more pronounced seasonal differences in brain and brain region sizes. The extent to which seasonal differences in brain region volumes vary with behaviour is unclear, but our data do suggest that seasonal plasticity is not limited to the hippocampus and that RGS is a useful mammalian species for understanding seasonal plasticity in an ecologically relevant context.
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Affiliation(s)
- R J Keeley
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada.
| | - D K Burger
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - D M Saucier
- Faculty of Science, University of Ontario Institute of Technology, Oshawa, ON L1H 7K4, Canada
| | - A N Iwaniuk
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
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Moser P. Evaluating negative-symptom-like behavioural changes in developmental models of schizophrenia. Eur Neuropsychopharmacol 2014; 24:774-87. [PMID: 24332891 DOI: 10.1016/j.euroneuro.2013.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 10/18/2013] [Accepted: 11/17/2013] [Indexed: 01/22/2023]
Abstract
Many lines of evidence suggest that schizophrenia has a major developmental component and that environmental factors that disrupt key stages of development, such as maternal stress during pregnancy as a result of infection or malnutrition, can increase the risk of developing schizophrenia in later life. This review examines how non-clinical neurodevelopmental models pertinent to schizophrenia have been evaluated for their ability to reproduce behavioural deficits related to the negative symptoms of schizophrenia. The more frequently used are the prenatal application of the mitotoxic agent methylazoxymethanol, prenatal immune challenge and the neonatal ventral hippocampus lesion model. In general they have been extensively evaluated in models considered relevant to positive symptoms of schizophrenia. In contrast, very few studies have examined tests related to negative symptoms and, when they have, it has almost exclusively been a social interaction model. Other aspects related to negative symptoms such as anhedonia, affective flattening and avolition have almost never been studied. Further studies examining other components of negative symptomatology are needed to more clearly associate these deficits with a schizophrenia-like profile as social withdrawal is a hallmark of many disorders. Although there are no truly effective treatments for negative symptoms, better characterisation with a broader range of drugs used in schizophrenia will be necessary to better evaluate the utility of these models. In summary, developmental models of schizophrenia have been extensively studied as models of positive symptoms but, given the unmet need in the clinic, the same effort now needs to be made with regard to negative symptoms.
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Affiliation(s)
- Paul Moser
- Centre de Recherche Pierre Fabre 17, Avenue Jean Moulin, 81106 Castres Cédex, France.
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8
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Abstract
Psychosis is an abnormal mental state characterized by disorganization, delusions and hallucinations. Animal models have become an increasingly important research tool in the effort to understand both the underlying pathophysiology and treatment of psychosis. There are multiple animal models for psychosis, with each formed by the coupling of a manipulation and a measurement. In this manuscript we do not address the diseases of which psychosis is a prominent comorbidity. Instead, we summarize the current state of affairs and future directions for animal models of psychosis. To accomplish this, our manuscript will first discuss relevant behavioral and electrophysiological measurements. We then provide an overview of the different manipulations that are combined with these measurements to produce animal models. The strengths and limitations of each model will be addressed in order to evaluate its cross-species comparability.
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Bellon A, Le Pen G, Matricon J, Jay TM, Krebs MO. Potential application as screening and drug designing tools of cytoarchitectural deficiencies present in three animal models of schizophrenia. Expert Opin Drug Discov 2013; 4:257-78. [PMID: 23489125 DOI: 10.1517/17460440902762794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND The development of new treatment alternatives for schizophrenia has been prevented by the unknown etiology of the illness and the divergence of results in the field. However, consistent neuropathological findings are emerging from anatomical areas known to be at the core of schizophrenia. If these deficiencies are replicated in animal models then such anomalies could become the target for a new generation of drugs. OBJECTIVE To determine if the methylazoxymethanol acetate (MAM) model, the heterozygote reeler mouse (HRM) and NMDA-antagonists treated rats replicate neuropathological deficits encountered in patients with schizophrenia and to establish if such changes could lead the search for developing novel treatment alternatives. METHODS Databases including MEDLINE, Cochrane and Ovid were searched; search terms included neuropathology, schizophrenia and animal models. RESULTS/CONCLUSIONS NMDA-antagonist treated animals partially replicate schizophrenia anomalies in parvalbumin positive interneurons. In contrast, neuroanatomical deficiencies replicated by the MAM model and the HRM in the hippocampus and the prefrontal cortex seem promising targets for future pharmacological research in schizophrenia. Such neuroanatomical findings along with evidence from molecules and genes associated with schizophrenia suggest new drugs should aim to correct deficits in the formation of dendrites and axons that seems to be implicated in this illness pathophysiology.
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Affiliation(s)
- Alfredo Bellon
- INSERM, Hôpital Sainte-Anne, Centre de Psychiatrie et Neurosciences, Laboratoire de Physiopathologie des Maladies Psychiatriques, U894, 2 ter rue d'Alésia, 75014 Paris, France +33 1 40788634 ; +33 1 45807293 ;
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10
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Palha JA, Santos NC, Marques F, Sousa J, Bessa J, Miguelote R, Sousa N, Belmonte-de-Abreu P. Do genes and environment meet to regulate cerebrospinal fluid dynamics? Relevance for schizophrenia. Front Cell Neurosci 2012; 6:31. [PMID: 22891052 PMCID: PMC3413907 DOI: 10.3389/fncel.2012.00031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 07/15/2012] [Indexed: 12/17/2022] Open
Abstract
Schizophrenia is a neurodevelopment disorder in which the interplay of genes and environment contributes to disease onset and establishment. The most consistent pathological feature in schizophrenic patients is an enlargement of the brain ventricles. Yet, so far, no study has related this finding with dysfunction of the choroid plexus (CP), the epithelial cell monolayer located within the brain ventricles that is responsible for the production of most of the cerebrospinal fluid (CSF). Enlarged brain ventricles are already present at the time of disease onset (young adulthood) and, of notice, isolated mild ventriculomegaly detected in utero is associated with subsequent mild neurodevelopmental abnormalities similar to those observed in children at high risk of developing schizophrenia. Here we propose that altered CP/CSF dynamics during neurodevelopment may be considered a risk, causative and/or participating factor for development of schizophrenia.
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Affiliation(s)
- Joana A Palha
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho Braga, Portugal
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11
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Brown PL, Shepard PD, Elmer GI, Stockman S, McFarland R, Mayo CL, Cadet JL, Krasnova IN, Greenwald M, Schoonover C, Vogel MW. Altered spatial learning, cortical plasticity and hippocampal anatomy in a neurodevelopmental model of schizophrenia-related endophenotypes. Eur J Neurosci 2012; 36:2773-81. [PMID: 22762562 DOI: 10.1111/j.1460-9568.2012.08204.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adult rats exposed to the DNA-methylating agent methylazoxymethanol on embryonic day 17 show a pattern of neurobiological deficits that model some of the neuropathological and behavioral changes observed in schizophrenia. Although it is generally assumed that these changes reflect targeted disruption of embryonic neurogenesis, it is unknown whether these effects generalise to other antimitotic agents administered at different stages of development. In the present study, neurochemical, behavioral and electrophysiological techniques were used to determine whether exposure to the antimitotic agent Ara-C later in development recapitulates some of the changes observed in methylazoxymethanol (MAM)-treated animals and in patients with schizophrenia. Male rats exposed to Ara-C (30 mg/kg/day) at embryonic days 19.5 and 20.5 show reduced cell numbers and heterotopias in hippocampal CA1 and CA2/3 regions, respectively, as well as cell loss in the superficial layers of the pre- and infralimbic cortex. Birth date labeling with bromodeoxyuridine reveals that the cytoarchitectural changes in CA2/3 are a consequence rather that a direct result of disrupted cortical neurogenesis. Ara-C-treated rats possess elevated levels of cortical dopamine and DOPAC (3,4-didyhydroxypheylacetic acid) but no change in norepinephrine or serotonin. Ara-C-treated rats are impaired in their ability to learn the Morris water maze task and showed diminished synaptic plasticity in the hippocampocortical pathway. These data indicate that disruption of neurogenesis at embryonic days 19.5 and 20.5 constitutes a useful model for the comparative study of deficits observed in other gestational models and their relationship to cognitive changes observed in schizophrenia.
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Affiliation(s)
- P Leon Brown
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
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Jones CA, Watson DJG, Fone KCF. Animal models of schizophrenia. Br J Pharmacol 2011; 164:1162-94. [PMID: 21449915 PMCID: PMC3229756 DOI: 10.1111/j.1476-5381.2011.01386.x] [Citation(s) in RCA: 527] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 03/09/2011] [Accepted: 03/12/2011] [Indexed: 12/27/2022] Open
Abstract
Developing reliable, predictive animal models for complex psychiatric disorders, such as schizophrenia, is essential to increase our understanding of the neurobiological basis of the disorder and for the development of novel drugs with improved therapeutic efficacy. All available animal models of schizophrenia fit into four different induction categories: developmental, drug-induced, lesion or genetic manipulation, and the best characterized examples of each type are reviewed herein. Most rodent models have behavioural phenotype changes that resemble 'positive-like' symptoms of schizophrenia, probably reflecting altered mesolimbic dopamine function, but fewer models also show altered social interaction, and learning and memory impairment, analogous to negative and cognitive symptoms of schizophrenia respectively. The negative and cognitive impairments in schizophrenia are resistant to treatment with current antipsychotics, even after remission of the psychosis, which limits their therapeutic efficacy. The MATRICS initiative developed a consensus on the core cognitive deficits of schizophrenic patients, and recommended a standardized test battery to evaluate them. More recently, work has begun to identify specific rodent behavioural tasks with translational relevance to specific cognitive domains affected in schizophrenia, and where available this review focuses on reporting the effect of current and potential antipsychotics on these tasks. The review also highlights the need to develop more comprehensive animal models that more adequately replicate deficits in negative and cognitive symptoms. Increasing information on the neurochemical and structural CNS changes accompanying each model will also help assess treatments that prevent the development of schizophrenia rather than treating the symptoms, another pivotal change required to enable new more effective therapeutic strategies to be developed.
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Affiliation(s)
- C A Jones
- School of Biomedical Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, UK
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Lazar NL, Neufeld RWJ, Cain DP. Contribution of nonprimate animal models in understanding the etiology of schizophrenia. J Psychiatry Neurosci 2011; 36:E5-29. [PMID: 21247514 PMCID: PMC3120891 DOI: 10.1503/jpn.100054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Schizophrenia is a severe psychiatric disorder that is characterized by positive and negative symptoms and cognitive impairments. The etiology of the disorder is complex, and it is thought to follow a multifactorial threshold model of inheritance with genetic and neurodevelop mental contributions to risk. Human studies are particularly useful in capturing the richness of the phenotype, but they are often limited to the use of correlational approaches. By assessing behavioural abnormalities in both humans and rodents, nonprimate animal models of schizophrenia provide unique insight into the etiology and mechanisms of the disorder. This review discusses the phenomenology and etiology of schizophrenia and the contribution of current nonprimate animal models with an emphasis on how research with models of neuro transmitter dysregulation, environmental risk factors, neurodevelopmental disruption and genetic risk factors can complement the literature on schizophrenia in humans.
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Affiliation(s)
- Noah L Lazar
- Department of Psychology, University of Western Ontario, London, Ont.
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14
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Abstract
The neurodegenerative aspect of schizophrenia presupposes gene-environmental interactions involving chromosomal abnormalities and obstetric/perinatal complications that culminate in predispositions that impart a particular vulnerability for drastic and unpredictable precipitating factors, such as stress or chemical agents. The notion of a neurodevelopmental progression to the disease state implies that early developmental insults, with neurodegenerative proclivities, evolve into structural brain abnormalities involving specific regional circuits and neurohumoral agents. This neurophysiological orchestration is expressed in the dysfunctionality observed in premorbid signs and symptoms arising in the eventual diagnosis, as well as the neurobehavioral deficits reported from animal models of the disorder. The relative contributions of perinatal insults, neonatal ventral hippocampus lesion, prenatal methylazoxymethanol acetate and early traumatic experience, as well as epigenetic contributions, are discussed from a neurodegenerative view of the essential neuropathology. It is implied that these considerations of factors that exert disruptive influences upon brain development, or normal aging, operationalize the central hub of developmental neuropathology around which the disease process may gain momentum. Nonetheless, the status of neurodegeneration in schizophrenia is somewhat tenuous and it is possible that brain imaging studies on animal models of the disorder, which may describe progressive alterations to cortical, limbic and ventricular structures similar to those of schizophrenic patients, are necessary to resolve the issue.
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Affiliation(s)
- Trevor Archer
- University of Gothenburg, Department of Psychology, Box 500, SE-40530, Gothenburg, Sweden.
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15
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Matricon J, Bellon A, Frieling H, Kebir O, Le Pen G, Beuvon F, Daumas-Duport C, Jay TM, Krebs MO. Neuropathological and Reelin deficiencies in the hippocampal formation of rats exposed to MAM; differences and similarities with schizophrenia. PLoS One 2010; 5:e10291. [PMID: 20421980 PMCID: PMC2858661 DOI: 10.1371/journal.pone.0010291] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 03/15/2010] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Adult rats exposed to methylazoxymethanol (MAM) at embryonic day 17 (E17) consistently display behavioral characteristics similar to that observed in patients with schizophrenia and replicate neuropathological findings from the prefrontal cortex of psychotic individuals. However, a systematic neuropathological analysis of the hippocampal formation and the thalamus in these rats is lacking. It is also unclear if reelin, a protein consistently associated with schizophrenia and potentially involved in the mechanism of action of MAM, participates in the neuropathological effects of this compound. Therefore, a thorough assessment including cytoarchitectural and neuromorphometric measurements of eleven brain regions was conducted. Numbers of reelin positive cells and reelin expression and methylation levels were also studied. PRINCIPAL FINDINGS Compared to untreated rats, MAM-exposed animals showed a reduction in the volume of entorhinal cortex, hippocampus and mediodorsal thalamus associated with decreased neuronal soma. The entorhinal cortex also showed laminar disorganization and neuronal clusters. Reelin methylation in the hippocampus was decreased whereas reelin positive neurons and reelin expression were unchanged. CONCLUSIONS Our results indicate that E17-MAM exposure reproduces findings from the hippocampal formation and the mediodorsal thalamus of patients with schizophrenia while providing little support for reelin's involvement. Moreover, these results strongly suggest MAM-treated animals have a diminished neuropil, which likely arises from abnormal neurite formation; this supports a recently proposed pathophysiological hypothesis for schizophrenia.
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Affiliation(s)
- Julien Matricon
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
| | - Alfredo Bellon
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
- * E-mail: (AB); (MOK)
| | - Helge Frieling
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Department of Psychiatry, Socialpsychiatry and Psychotherapy, Hannover Medical School, Hannover, Germany
| | - Oussama Kebir
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
| | - Gwenaëlle Le Pen
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
| | - Frédéric Beuvon
- Neuropathology unit, Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
- INSERM U894, Laboratoire de Plasticité gliale et tumeurs cérébrales, Centre de Psychiatrie et Neurosciences, Paris, France
| | - Catherine Daumas-Duport
- Neuropathology unit, Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
- INSERM U894, Laboratoire de Plasticité gliale et tumeurs cérébrales, Centre de Psychiatrie et Neurosciences, Paris, France
| | - Thérèse M. Jay
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
| | - Marie-Odile Krebs
- INSERM U894, Laboratoire de Physiopathologie des Maladies Psychiatriques, Centre de Psychiatrie et Neurosciences, Paris, France
- Université Paris Descartes, Faculté de Médecine Paris Descartes, Hôpital Sainte-Anne, Paris, France
- * E-mail: (AB); (MOK)
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16
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Jaaro-Peled H, Ayhan Y, Pletnikov MV, Sawa A. Review of pathological hallmarks of schizophrenia: comparison of genetic models with patients and nongenetic models. Schizophr Bull 2010; 36:301-13. [PMID: 19903746 PMCID: PMC2833125 DOI: 10.1093/schbul/sbp133] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Schizophrenia is a condition that impairs higher brain functions, some of which are specific to humans. After identification of susceptibility genes for schizophrenia, many efforts have been made to generate genetics-based models for the disease. It is under debate whether behavioral deficits observed in rodents are sufficient to characterize these models. Alternatively, anatomical and neuropathological changes identified in brains of patients with schizophrenia may be utilized as translatable characteristics between humans and rodents, which are important for validation of the models. Here, we overview such anatomical and neuropathological changes in humans: enlarged ventricles, dendritic changes in the pyramidal neurons, and alteration of specific subtypes of interneurons. In this review, we will overview such morphological changes in brains from patients with schizophrenia. Then, we will describe that some of these alterations are already recapitulated even in classic nongenetic models for schizophrenia. Finally, in comparison with the changes in patients and nongenetic models, we will discuss the anatomical and neuropathological manifestation in genetic models for schizophrenia.
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Affiliation(s)
- Hanna Jaaro-Peled
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287
| | - Yavuz Ayhan
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287
| | - Mikhail V. Pletnikov
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287
| | - Akira Sawa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287,To whom correspondence should be addressed; tel: 1-410-9554726, fax: 410-6141792, e-mail:
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17
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Abstract
The neurodevelopmental hypothesis of schizophrenia asserts that the underlying pathology of schizophrenia has its roots in brain development and that these brain abnormalities do not manifest themselves until adolescence or early adulthood. Animal models based on developmental manipulations have provided insight into the vulnerability of the developing fetus and the importance of the early environment for normal maturation. These models have provided a wide range of validated approaches to answer questions regarding environmental influences on both neural and behavioral development. In an effort to better understand the developmental hypothesis of schizophrenia, animal models have been developed, which seek to model the etiology and/or the pathophysiology of schizophrenia or specific behaviors associated with the disease. Developmental models specific to schizophrenia have focused on epidemiological risk factors (e.g., prenatal viral insult, birth complications) or more heuristic models aimed at understanding the developmental neuropathology of the disease (e.g., ventral hippocampal lesions). The combined approach of behavioral and neuroanatomical evaluation of these models strengthens their utility in improving our understanding of the pathophysiology of schizophrenia and developing new treatment strategies.
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Affiliation(s)
- Susan B Powell
- University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0804, USA.
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18
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Sawa A. Genetic animal models for schizophrenia: advantages and limitations of genetic manipulation in drosophila, zebrafish, rodents, and primates. PROGRESS IN BRAIN RESEARCH 2009; 179:3-6. [PMID: 20302812 DOI: 10.1016/s0079-6123(09)17901-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Schizophrenia is a debilitating mental illness in which major initial risks of the disease during neurodevelopment may disturb postnatal brain maturation, which results in onset after puberty. Family, twin, and adoption studies have suggested an important role for genetic factors in the etiology of schizophrenia. To address the etiology-associated mechanisms and disease course, use of genetic models, that is, manipulation of genetic susceptibility factors, is currently considered to be a powerful tool for biological studies. In this manuscript, advantages and possible limitations in manipulating genetic susceptibility factors for schizophrenia toward modeling the disease are discussed. In addition to mouse models, the potential to use drosophila, zebrafish, and primates is underscored.
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Affiliation(s)
- Akira Sawa
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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19
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Hippocampal dysfunction and disruption of dopamine system regulation in an animal model of schizophrenia. Neurotox Res 2009; 14:97-104. [PMID: 19073417 DOI: 10.1007/bf03033801] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Studies into the pathophysiology of schizophrenia have consistently demonstrated a dysfunction of dopamine (DA) system regulation in this disorder. This includes hyper-responsivity to DA agonists, the therapeutic efficacy of DA antagonists, and augmented striatal DA release in response to amphetamine. Nonetheless, there is little evidence for a pathological alteration with the DA system itself in schizophrenia. Instead, it is suggested that the disturbance lies in the manner by which the DA system is regulated. Recently, rodent models of schizophrenia have been advanced based on developmental disruption that recapitulates many of the symptoms observed in human schizophrenia patients. We found that administration of the mitotoxin methylazoxymethanol acetate (MAM) to rats at gestational day 17 leads to adult rats that exhibit neuroanatomical, pharmacological, and behavioral characteristics consistent with schizophrenia. These rats also exhibit hyperactivity within the ventral subiculum of the hippocampus that corresponds to a loss of parvalbumin-containing interneurons. This hyperactivity causes an increase in the population activity of the DA neurons (i.e., more DA neurons are firing spontaneously), thus increasing the responsivity of the DA system to stimuli. When the ventral subiculum is inactivated, DA neuron population activity is restored to baseline, and the hyper-responsivity to amphetamine is normalized to that observed in control rats. These findings demonstrate a direct link between the hippocampal pathophysiology, interneuronal alterations, and hyperdopaminergic state observed in the schizophrenia patient. Moreover, this suggests an alternate pharmacotherapeutic approach based on the normalization of hippocampal activity in the treatment of schizophrenia in humans.
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20
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Hazane F, Krebs MO, Jay TM, Le Pen G. Behavioral perturbations after prenatal neurogenesis disturbance in female rat. Neurotox Res 2009; 15:311-20. [PMID: 19384565 DOI: 10.1007/s12640-009-9035-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 12/18/2008] [Accepted: 12/18/2008] [Indexed: 10/20/2022]
Abstract
The exposure to methylazoxymethanol (MAM) at embryonic day 17 (E17) results in behavioral anomalies in male rats that mimic several features of schizophrenia, including their emergence after puberty. Given that both men and women are likely to develop this illness and that currently no animal model is validated for females, we examined the behavioral consequences of E17 MAM exposure in female rats. We compared E17 MAM- and saline-exposed female rats before and/or after puberty for spontaneous activity, alternance and spatial recognition (Y-maze), spatial learning (Morris water maze), and sensory gating using the prepulse inhibition task. MAM-exposed female rats exhibited a significant increase in spontaneous locomotor activity in a novel environment, compared to sham animals, which emerged only after puberty. They also had deficits in spontaneous alternation performance and spatial recognition in a Y-maze as well as reference memory deficits in a Morris water maze task. Lastly, MAM-exposed female rats spent significantly less time in social interaction at both pre- and post-puberty and had a deficit in prepulse inhibition of the startle reflex (PPI) at adulthood. In conclusion, the present results show that, in female rat, exposure to MAM at E17 results in a pattern of behavioral changes that, on the whole, mimic positive, negative, and cognitive dimensions of schizophrenia. E17 MAM exposure thus appears to be a valid model for schizophrenia in both males and females.
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Affiliation(s)
- Franck Hazane
- Laboratory of Pathophysiology of Psychiatric Diseases, Center of Psychiatry and Neurosciences, INSERM U894, Sainte-Anne Hospital, 2ter rue d'Alésia, 75014, Paris, France
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21
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Schizopsychotic symptom-profiles and biomarkers: Beacons in diagnostic labyrinths. Neurotox Res 2008; 14:79-96. [DOI: 10.1007/bf03033800] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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22
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Burcham PC. Toxicology down under: past achievements, present realities, and future prospects. Chem Res Toxicol 2008; 21:967-70. [PMID: 18442270 DOI: 10.1021/tx8001252] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Aberrant hippocampal activity underlies the dopamine dysregulation in an animal model of schizophrenia. J Neurosci 2007; 27:11424-30. [PMID: 17942737 DOI: 10.1523/jneurosci.2847-07.2007] [Citation(s) in RCA: 328] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Evidence supports a dysregulation of subcortical dopamine (DA) system function as a common etiology of psychosis; however, the factors responsible for this aberrant DA system responsivity have not been delineated. Here, we demonstrate in an animal model of schizophrenia that a pathologically enhanced drive from the ventral hippocampus (vHipp) can result in aberrant dopamine neuron signaling. Adult rats in which development was disrupted by prenatal methylazoxymethanol acetate (MAM) administration display a significantly greater number of spontaneously firing ventral tegmental DA neurons. This appears to be a consequence of excessive hippocampal activity because, in MAM-treated rats, vHipp inactivation completely reversed the elevated DA neuron population activity and also normalized the augmented amphetamine-induced locomotor behavior. These data provide a direct link between hippocampal dysfunction and the hyper-responsivity of the DA system that is believed to underlie the augmented response to amphetamine in animal models and psychosis in schizophrenia patients.
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24
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Dawe GS, Ratty AK. Thechakragati mouse: A mouse model for rapidin vivo screening of antipsychotic drug candidates. Biotechnol J 2007; 2:1344-52. [PMID: 17886239 DOI: 10.1002/biot.200700145] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The chakragati (ckr) mouse is a serendipitously discovered insertional transgenic mutant that exhibits circling and hyperactivity. Studies of social behavior, sensorimotor gating and ventricular anatomy suggest that the ckr mouse models aspects of schizophrenia. The underlying genetic and neurodevelopmental mechanisms remain to be elucidated but appear to result in a hemispheric asymmetry in striatal D(2)-like dopamine receptors. The circling is inhibited by administration of antipsychotic drugs and so lends itself to in vivo prospective screening for novel molecules with antipsychotic-like activity. Using the ckr mouse we have applied an in vivo first approach to screening for antipsychotic drug candidates. This offers the advantage of early indication of central nervous system bioavailability and potential toxicological concerns. Additionally, in vivo first screening in the ckr mouse is not biased by any particular neurotransmitter hypothesis of the disease, and so has the potential to identify compounds modifying the behavioral output by novel mechanisms of interaction with the underlying brain circuitry. Thus, in contrast to the classical strategy of hypothesis-driven in vitro screening for drugs fitting a "receptor model" of the disease, the ckr mouse screen has greater potential to identify lead molecules for a new generation antipsychotics with novel mechanisms of action.
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Affiliation(s)
- Gavin S Dawe
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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25
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Di Fausto V, Fiore M, Aloe L. Exposure in fetus of methylazoxymethanol in the rat alters brain neurotrophins' levels and brain cells' proliferation. Neurotoxicol Teratol 2007; 29:273-81. [PMID: 17142008 DOI: 10.1016/j.ntt.2006.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Revised: 10/12/2006] [Accepted: 10/22/2006] [Indexed: 02/08/2023]
Abstract
Changes during gestation have been shown to induce brain maldevelopment associated with changes in neurotrophins as nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and neuropsychiatric disorders in humans. A rat model of altered prenatal brain development resembling the onset of schizophrenia has been obtained by administering in fetus methylazoxymethanol (MAM) at gestational day 12 which impairs the growth of limbic pathways between the entorhinal cortex and the hippocampus. Using the MAM model we studied in young rats the brain levels of both NGF/BDNF and their main receptors, TrkA/TrkB, to investigate whether or not changes in neurotrophins could affect the presence of brain BrdU positive cells. We found increased NGF and BDNF protein levels, associated with elevated TrkA and TrkB expression, in the hippocampus, entorhinal cortex, olfactory lobes and subventricular zone (SVZ), brain areas playing a key role in the production and migration of new dividing cells. We also found higher levels of BrdU positive cells in the SVZ and hippocampus but not a significant potentiation in the entorhinal cortex and olfactory lobes. All together the findings indicate that prenatal MAM exposure in young rats may elicit both neurotrophins' elevation and cell proliferation in limbic brain areas.
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Affiliation(s)
- Veronica Di Fausto
- Institute of Neurobiology and Molecular Medicine, CNR-EBRI Via del Fosso di Fiorano, 64, 00143 Rome, Italy
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26
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Kisby GE, Olivas A, Standley M, Lu X, Pattee P, O’Malley J, Li X, Muniz J, Nagalla SR. Genotoxicants target distinct molecular networks in neonatal neurons. ENVIRONMENTAL HEALTH PERSPECTIVES 2006; 114:1703-12. [PMID: 17107856 PMCID: PMC1665395 DOI: 10.1289/ehp.9073] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
BACKGROUND Exposure of the brain to environmental agents during critical periods of neuronal development is considered a key factor underlying many neurologic disorders. OBJECTIVES In this study we examined the influence of genotoxicants on cerebellar function during early development by measuring global gene expression changes. METHODS We measured global gene expression in immature cerebellar neurons (i.e., granule cells) after treatment with two distinct alkylating agents, methylazoxymethanol (MAM) and nitrogen mustard (HN2). Granule cell cultures were treated for 24 hr with MAM (10-1,000 microM) or HN2 (0.1-20 microM) and examined for cell viability, DNA damage, and markers of apoptosis. RESULTS Neuronal viability was significantly reduced (p < 0.01) at concentrations > 500 microM for MAM and > 1.0 microM for HN2; this correlated with an increase in both DNA damage and markers of apoptosis. Neuronal cultures treated with sublethal concentrations of MAM (100 microM) or HN2 (1.0 microM) were then examined for gene expression using large-scale mouse cDNA microarrays (27,648). Gene expression results revealed that a) global gene expression was predominantly up-regulated by both genotoxicants; b) the number of down-regulated genes was approximately 3-fold greater for HN2 than for MAM; and c) distinct classes of molecules were influenced by MAM (i.e, neuronal differentiation, the stress and immune response, and signal transduction) and HN2 (i.e, protein synthesis and apoptosis). CONCLUSIONS These studies demonstrate that individual genotoxicants induce distinct gene expression signatures. Further study of these molecular networks may explain the variable response of the developing brain to different types of environmental genotoxicants.
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Affiliation(s)
- Glen E. Kisby
- Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, Portland, Oregon
| | - Antoinette Olivas
- Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, Portland, Oregon
| | - Melissa Standley
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Xinfang Lu
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Patrick Pattee
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Jean O’Malley
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Xiaorong Li
- Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, Portland, Oregon
| | - Juan Muniz
- Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, Portland, Oregon
| | - Srinavasa R. Nagalla
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, Oregon
- Address correspondence to S. Nagalla, Department of Pediatrics, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239 USA. Telephone: (503) 494-1928. Fax: (503) 494-4821. E-mail:
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27
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Powell CM, Miyakawa T. Schizophrenia-relevant behavioral testing in rodent models: a uniquely human disorder? Biol Psychiatry 2006; 59:1198-207. [PMID: 16797265 PMCID: PMC3928106 DOI: 10.1016/j.biopsych.2006.05.008] [Citation(s) in RCA: 274] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 05/08/2006] [Accepted: 05/15/2006] [Indexed: 11/26/2022]
Abstract
Animal models are extremely useful tools in defining pathogenesis and treatment of human disease. Creating adequate animal models of complex neuropsychiatric disorders such as schizophrenia represents a particularly difficult challenge. In the case of schizophrenia, little is certain regarding the etiology or pathophysiology of the human disease. In addition, many symptoms of the disorder are difficult to measure directly in rodents. These challenges have not daunted neuroscientists who are capitalizing on even subtle overlaps between this uniquely human disorder and rodent behavior. In this perspective, we detail the features of ideal animal models of schizophrenia, the potential utility of such models, and the rodent behaviors used to model certain aspects of schizophrenia. The development of such models will provide critical tools to understand the pathogenesis of schizophrenia and novel insights into therapeutic approaches to this complex disorder.
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Affiliation(s)
- Craig M Powell
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-8813, USA.
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28
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Abstract
1. An optimal intra-uterine environment is critical for normal development of the brain. It is now thought that abnormal development in a compromised prenatal and/or early postnatal environment may be a risk factor for several neurological disorders that manifest postnatally, such as cerebral palsy, schizophrenia and epilepsy. 2. The present review examines some of the effects of abnormal prenatal brain development and focuses on one disorder that has been hypothesized to have, at least in part, an early neurodevelopmental aetiology: schizophrenia. 3. The key neuropathological alterations and changes in some of the neurotransmitter systems observed in patients with schizophrenia are reviewed. Evidence in support of a neurodevelopmental hypothesis for schizophrenia is examined. 4. A summary of the animal models that have been used by researchers in an attempt to elucidate the origins of this disorder is presented. Although no animal model of a complex human disorder is ever likely to emulate deficits in all aspects of structure and function observed in patients with a neuropsychiatric illness, our findings and those of others give support to the early neurodevelopmental hypothesis. 5. Thus, it is possible that an adverse event in utero disrupts normal brain development and creates a vulnerability of the brain that predisposes an already at-risk individual (e.g. genetic inheritance) to develop the disorder later in life.
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Affiliation(s)
- Alexandra E Rehn
- Department of Anatomy and Cell Biology, The University of Melbourne, Parkville, Victoria, Australia
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29
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Kisby GE, Standley M, Lu X, O'Malley J, Lin B, Muniz J, Luo NL, Pattee P, Back SA, Nagalla SR. Molecular networks perturbed in a developmental animal model of brain injury. Neurobiol Dis 2005; 19:108-18. [PMID: 15837566 DOI: 10.1016/j.nbd.2004.11.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 11/16/2004] [Accepted: 11/23/2004] [Indexed: 11/29/2022] Open
Abstract
Methylazoxymethanol (MAM) is widely used as a developmental neurotoxin and exposure to its glucoside (i.e., cycasin) is associated with the prototypical neurological disorder western Pacific ALS/PDC. However, the specific molecular targets that play a key role in MAM-induced brain injury remain unclear. To reveal potential molecular networks targeted by MAM in the developing nervous system, we examined characteristic phenotypic changes (DNA damage, cytoarchitecture) induced by MAM and their correlation with gene expression differences using microarray assays (27,648 genes). Three day-old postnatal C57BL/6 mice (PND3) received a single injection of MAM and the cerebellum and cerebral cortex of PND4, 8, 15, and 22 mice were analyzed. DNA damage was detected in both the cerebellum (N7-mGua, TUNEL labeling) and cerebral cortex (N7-mGua) of PND4 mice, but progressive disruption of the cytoarchitecture was restricted to the cerebellum. A majority (>75%) of the genes affected (cerebellum 636 genes, cortex 1080 genes) by MAM were developmentally regulated, with a predominant response early (PND4) in the cerebellum and delayed (PND8 and 15) in the cerebral cortex. The genes and pathways (e.g., proteasome) affected by MAM in the cerebellum are distinct from cortex. The genes perturbed in the cerebellum reflect critical cellular processes such as development (17%), cell cycle (7%), protein metabolism (12%), and transcriptional regulation (9%) that could contribute to the observed cytoarchitectural disruption of the cerebellum. This study demonstrates for the first time that specific genes and molecular networks are affected by MAM during CNS development. Further investigation of these targets will help to understand how disruption of these developmental programs could contribute to chronic brain injury or neurodegenerative disease.
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Affiliation(s)
- G E Kisby
- Center for Research on Occupational and Environmental Toxicology (CROET), Portland, OR 97239, USA
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30
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Leng A, Jongen-Rêlo AL, Pothuizen HHJ, Feldon J. Effects of prenatal methylazoxymethanol acetate (MAM) treatment in rats on water maze performance. Behav Brain Res 2005; 161:291-8. [PMID: 15922056 DOI: 10.1016/j.bbr.2005.02.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 02/15/2005] [Accepted: 02/18/2005] [Indexed: 11/17/2022]
Abstract
Prenatal methylazoxymethanol acetate (MAM) treatment has been shown to induce morphological abnormalities in cortical areas of the offspring. Based on the neuroanatomical and behavioural abnormalities, this treatment has been suggested as a useful animal model for schizophrenia. In a previous study (Jongen-Relo AL, Leng A, Luber M, Pothuizen HHJ, Weber L, Feldon J. The prenatal methylazoxymethanol acetate treatment: a neurodevelopmental animal model for schizophrenia? Behav Brain Res 2004;149:159-81) we have studied MAM-treated animals in a series of behavioural tests related to schizophrenia, such as latent inhibition and pre-pulse inhibition of the acoustic startle response to establish the validity of prenatal MAM treatment (20mg/kg i.p. on gestational days 9-15; MAM 9-MAM 15). We found that, apart from a marginal effect of increased activity in the open field, the MAM treatment on gestational day 15 was behaviourally ineffective. Here, we extended our previous study to a water maze experiment conducted in the same batch of animals as presented previously (MAM 12-MAM 15). MAM-treated animals showed similar water maze performance compared with control animals during the acquisition phase and the probe tests. However, during the reversal phase, MAM 15 animals showed impaired acquisition of the new platform location. This might indicate some cognitive deficits in MAM 15 animals in terms of working memory or behavioural flexibility. However, in combination with the lack of behavioural abnormalities of MAM 12-MAM 15 animals in several other tests related to schizophrenia in the previously reported study, the use of MAM treatment (MAM 12-MAM 15) as a valid model for schizophrenia still remains debatable.
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Affiliation(s)
- Andreas Leng
- Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland
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31
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Abstract
Understanding the etiology and pathogenesis schizophrenia and depression is a major challenge facing psychiatry. One hypothesis is that these disorders are secondary to a malfunction of neurotrophic factors. Inappropriate neurotrophic support during brain development could lead to structural disorganisation in which neuronal networks are established in a nonoptimal manner. Inadequate neurotrophic support in adult individuals could ultimately be an underlying mechanism leading to decreased capacity of brain to adaptive changes and increased vulnerability to neurotoxic damage. Brain-derived neurotrophic factor (BDNF) is a mediator involved in neuronal survival and plasticity of dopaminergic, cholinergic, and serotonergic neurons in the central nervous system (CNS). In this review, we summarize findings regarding altered BDNF in schizophrenia and depression and animal models, as well as the effects of antipsychotic and antidepressive treatments on the expression of BDNF.
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Affiliation(s)
- F Angelucci
- Institute of Neurology, Catholic University, Largo Gemelli, Rome, Italy
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32
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Jelsing J, Olsen AK, Cumming P, Gjedde A, Hansen AK, Arnfred S, Hemmingsen R, Pakkenberg B. A volumetric screening procedure for the Göttingen minipig brain. Exp Brain Res 2005; 162:428-35. [PMID: 15668795 DOI: 10.1007/s00221-004-2026-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Accepted: 06/14/2004] [Indexed: 10/25/2022]
Abstract
A screening procedure was developed to provide quantitative estimates of structural parameters, regional volumes and neuron number, in a neurotoxicologic study of the Göttingen minipig brain. The study material consisted of normal controls and brains collected from young minipigs which had been exposed in utero to the mitotic inhibitor methylazoxymethanol acetate (MAM). Based on stereological principles and systematic sampling techniques, volumetric data from pre-selected regions of the pig brain was obtained using Cavalieri's principles and point-counting. Secondarily, estimates of total hemispheric neocortical cell numbers were obtained from pre-selected groups to test the potential effect of MAM on neuron number. No significant differences were observed in volume of the pre-selected regions of MAM intoxicated pigs nor in estimates of total neocortical neuron number.
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Affiliation(s)
- J Jelsing
- Research Laboratory for Stereology and Neuroscience, University Hospital Copenhagen, Bispebjerg, Denmark.
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33
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Meyer U, Feldon J, Schedlowski M, Yee BK. Towards an immuno-precipitated neurodevelopmental animal model of schizophrenia. Neurosci Biobehav Rev 2005; 29:913-47. [PMID: 15964075 DOI: 10.1016/j.neubiorev.2004.10.012] [Citation(s) in RCA: 370] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Revised: 10/19/2004] [Accepted: 10/19/2004] [Indexed: 01/18/2023]
Abstract
Epidemiological studies have indicated an association between maternal bacterial and viral infections during pregnancy and the higher incidence of schizophrenia in the resultant offspring post-puberty. One hypothesis asserts that the reported epidemiological link is mediated by prenatal activation of the foetal immune system in response to the elevation of maternal cytokine level due to infection. Here, we report that pregnant mouse dams receiving a single exposure to the cytokine-releasing agent, polyriboinosinic-polyribocytidilic acid (PolyI:C; at 2.5, 5.0, or 10.0 mg/kg) on gestation day 9 produced offspring that subsequently exhibited multiple schizophrenia-related behavioural deficits in adulthood, in comparison to offspring from vehicle injected or non-injected control dams. The efficacy of the PolyI:C challenge to induce cytokine responses in naïve non-pregnant adult female mice and in foetal brain tissue when injected to pregnant mice were further ascertained in separate subjects: (i) a dose-dependent elevation of interleukin-10 was detected in the adult female mice at 1 and 6h post-injection, (ii) 12 h following prenatal PolyI:C challenge, the foetal levels of interleukin-1beta were elevated. The spectrum of abnormalities included impairments in exploratory behaviour, prepulse inhibition, latent inhibition, the US-pre-exposure effect, spatial working memory; and enhancement in the locomotor response to systemic amphetamine (2.5 mg/kg, i.p.) as well as in discrimination reversal learning. The neuropsychological parallels between prenatal PolyI:C treatment in mice and psychosis in humans, demonstrated here, leads us to conclude that prenatal PolyI:C treatment represents one of the most powerful environmental-developmental models of schizophrenia to date. The uniqueness of this model lies in its epidemiological and immunological relevance. It is, sui generis, ideally suited for the investigation of the neuropsychoimmunological mechanisms implicated in the developmental aetiology and disease processes of schizophrenia.
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Affiliation(s)
- Urs Meyer
- Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, Schwerzenbach 8603, Switzerland
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34
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Flagstad P, Mørk A, Glenthøj BY, van Beek J, Michael-Titus AT, Didriksen M. Disruption of neurogenesis on gestational day 17 in the rat causes behavioral changes relevant to positive and negative schizophrenia symptoms and alters amphetamine-induced dopamine release in nucleus accumbens. Neuropsychopharmacology 2004; 29:2052-64. [PMID: 15199377 DOI: 10.1038/sj.npp.1300516] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gestational disruption of neurodevelopment has been proposed to lead to pathophysiological changes similar to those underlying schizophrenia. We induced such disruption by treating pregnant rat dams with methylazoxymethanol acetate (MAM) on gestational day 17 (GD17). Total brain size and that of the prefrontal cortex and hippocampus were reduced in adult rats exposed prenatally to MAM. When locomotor activity was assessed in an open field, MAM-exposed rats were hyper-responsive to a mild stress and to amphetamine (2 mg/kg, s.c.). They also engaged in less social interaction than controls. We studied, by microdialysis, the effect of amphetamine on extracellular dopamine in the nucleus accumbens and the medial prefrontal cortex of freely moving control and MAM-exposed rats. Amphetamine (2 mg/kg, s.c.) induced an increase in dopamine release that was larger in the nucleus accumbens of MAM-exposed rats than in controls, whereas no difference was seen in the medial prefrontal cortex. In controls, amphetamine infused into the medial prefrontal cortex (50 microM) led to a slight decrease in extracellular dopamine in the nucleus accumbens. This effect was absent in MAM-exposed rats, where a transient increase in nucleus accumbens dopamine levels was seen after amphetamine infusion. These results show that the late gestational disruption of neurogenesis in the rat leads to behavioral changes that mimic positive and negative schizophrenia symptoms, and also to a dysregulation of subcortical dopamine neurotransmission. This study contributes to the evaluation of the validity of the prenatal MAM GD17 treatment in rats as an animal model for schizophrenia.
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Affiliation(s)
- Peter Flagstad
- Department of Psychopharmacology, H Lundbeck A/S, Copenhagen-Valby, Denmark.
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35
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Fiore M, Grace AA, Korf J, Stampachiacchiere B, Aloe L. Impaired brain development in the rat following prenatal exposure to methylazoxymethanol acetate at gestational day 17 and neurotrophin distribution. Neuroreport 2004; 15:1791-5. [PMID: 15257149 DOI: 10.1097/01.wnr.0000135934.03635.6a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Several neuropsychiatric disorders, including schizophrenia, are the consequence of a disrupted development of the CNS. Accordingly, intrauterine exposure to toxins may increase the risk for psychopathology. We investigated whether prenatal exposure of rats to the neurotoxin methylazoxymethanol acetate led to long-term changes in cerebral neurotrophin levels. We measured the brain levels of nerve growth factor and brain derived neurotrophic factor in young adult and adult rats. Decreased nerve growth factor or brain derived neurotrophic factor were found in the parietal cortex accompanied by altered neurotrophin content in the hippocampus and entorhinal cortex. The present study is the first to show long-lasting effects of a single prenatal exposure to a neurotoxin on adult levels of neurotrophins in brain regions implicated in neuropsychiatric disorders.
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Affiliation(s)
- Marco Fiore
- Department of Biological Psychiatry, University of Groningen, Hanzeplein 1, 9713 EZ Groningen, The Netherlands.
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36
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Gourevitch R, Rocher C, Le Pen G, Krebs MO, Jay TM. Working memory deficits in adult rats after prenatal disruption of neurogenesis. Behav Pharmacol 2004; 15:287-92. [PMID: 15252279 DOI: 10.1097/01.fbp.0000135703.48799.71] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We investigated the cognitive consequences of a prenatal injection of the mitotic inhibitor methylazoxymethanol (MAM) into pregnant rats at embryonic day 15 (E15) or 17 (E17). The male offspring were tested when adult on a version of the radial-arm maze task that assesses spatial working memory with an extended delay, where performance is dependent, in part, on the hippocampal-prefrontal circuit. A major impairment of spatial learning was observed in E15 MAM rats. However, the E17 MAM rats did learn the rule but were impaired selectively in the 30-min delay-interposed task. Morphologically, the E15 MAM rats exhibited dramatic gross brain abnormalities, whereas the E17 MAM animals displayed aberrant cell migration in the hippocampus and a disrupted laminar pattern in the neocortex. These results suggest that late gestational MAM injection (E17) causes a cognitive impairment in a prefrontal cortex-hippocampus-dependent working memory task. This approach could provide a new developmental model of disorders associated with working memory deficits, such as schizophrenia.
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Affiliation(s)
- R Gourevitch
- INSERM E0117, Hôpital Sainte-Anne, 2 ter rue d'Alésia, Paris, France.
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37
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Jongen-Rêlo AL, Leng A, Lüber M, Pothuizen HHJ, Weber L, Feldon J. The prenatal methylazoxymethanol acetate treatment: a neurodevelopmental animal model for schizophrenia? Behav Brain Res 2004; 149:159-81. [PMID: 15129780 DOI: 10.1016/s0166-4328(03)00228-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The prenatal methylazoxymethanol acetate (MAM) treatment has been proposed as a suitable model for the neurodevelopmental aspects of schizophrenia since the morphological abnormalities it induces in the brain are subtle and in line with most reports of neuropathology in schizophrenic brains. However, the functional aspects of this treatment have not been investigated with behavioural paradigms that are relevant for the psychopathology of the symptoms of schizophrenia. In the present study, we investigated the validity of the prenatal MAM treatment as a developmental model for schizophrenia with a prepulse inhibition of the acoustic startle reflex, latent inhibition, locomotor activity, and cognition and emotionality with freezing in fear conditioning paradigms. We have conducted two studies: in Study I, MAM was injected from E09 to E12, and in Study II MAM was administered at later stages in the embryonic development, from E12 to E15. Morphologically, the prenatal MAM treatment induced mild to severe reduction in brain weights and in the entorhinal cortex, prefrontal cortex and striatum volumes, the severity of the effects depending on the timing of administration. However, despite the morphological abnormalities induced by the MAM treatments, no behavioural deficits were observed in the MAM-treated animals when compared to Controls in prepulse inhibition, latent inhibition with the two-way active avoidance, and in the freezing paradigms. Therefore, due to the consistent lack of treatment effect observed in the present investigation, we conclude that the prenatal MAM treatment has no validity as a behavioural model for schizophrenia.
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Affiliation(s)
- Ana L Jongen-Rêlo
- Behavioural Neurobiology Laboratory, Swiss Federal Institute of Technology, Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland
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Angelucci F, Mathé AA, Aloe L. Neurotrophic factors and CNS disorders: findings in rodent models of depression and schizophrenia. PROGRESS IN BRAIN RESEARCH 2004; 146:151-65. [PMID: 14699963 DOI: 10.1016/s0079-6123(03)46011-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are proteins involved in neuronal survival and plasticity of dopaminergic, cholinergic and serotonergic neurons in the central nervous system (CNS). Loss of neurons in specific brain regions has been found in depression and schizophrenia, and this chapter summarizes the findings of altered neurotrophins in animal models of those two disorders under baseline condition and following antidepressive and antipsychotic treatments. In a model of depression (Flinders sensitive line/Flinders resistant line; FSL/FRL rats), increased NGF and BDNF concentrations were found in frontal cortex of female, and in occipital cortex of male 'depressed' FSL compared to FRL control rats. Using the same model, the effects of electroconvulsive stimuli (ECS) and chronic lithium treatment on brain NGF, BDNF and glial cell line-derived neurotrophic factors were investigated. ECS and lithium altered the brain concentrations of neurotrophic factors in the hippocampus, frontal cortex, occipital cortex and striatum. ECS mimic the effects of electroconvulsive therapy (ECT) that is an effective treatment for depression and also schizophrenia. Since NGF and BDNF may also be changed in the CNS of animal models of schizophrenia, we investigated whether treatment with antipsychotic drugs (haloperidol, risperidone, and olanzapine) affects the constitutive levels of NGF and BDNF in the CNS. Both typical and atypical antipsychotic drugs altered the regional brain levels of NGF and BDNF. Other studies also demonstrated that these drugs differentially altered neurotrophin mRNAs. Overall, these studies indicate that alteration of brain level of NGF and BDNF could constitute part of the biochemical alterations induced by antipsychotic drugs.
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Affiliation(s)
- Francesco Angelucci
- Institute of Neurology, Catholic University, Largo Gemelli 8, I-00168, Rome, Italy.
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Zuckerman L, Rehavi M, Nachman R, Weiner I. Immune activation during pregnancy in rats leads to a postpubertal emergence of disrupted latent inhibition, dopaminergic hyperfunction, and altered limbic morphology in the offspring: a novel neurodevelopmental model of schizophrenia. Neuropsychopharmacology 2003; 28:1778-89. [PMID: 12865897 DOI: 10.1038/sj.npp.1300248] [Citation(s) in RCA: 370] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prenatal exposure to infection is associated with increased liability to schizophrenia, and it is believed that such an association is mediated by the maternal immune response, in particular, the proinflammatory cytokines released by the maternal immune system, which may disrupt fetal brain development. Impaired capacity to ignore irrelevant stimuli is one of the central deficits in schizophrenia, and is manifested, among others, in loss of latent inhibition (LI), a phenomenon whereby repeated inconsequential pre-exposure to a stimulus impairs its subsequent capacity to signal significant consequences. We tested the effects of prenatal immune activation induced by peripheral administration of the synthetic cytokine releaser polyriboinosinic-polyribocytidilic acid (poly I : C) to pregnant dams, on LI in juvenile and adult offspring. Consistent with the characteristic maturational delay of schizophrenia, prenatal immune activation did not affect LI in the juvenile offspring, but led to LI disruption in adulthood. Both haloperidol (0.1 mg/kg) and clozapine (5 mg/kg) reinstated LI in the adult offspring. In addition, prenatal immune activation led to a postpubertal emergence of increased sensitivity to the locomotor-stimulating effects of amphetamine and increased in vitro striatal dopamine release, as well as to morphological alterations in the hippocampus and the entorhinal cortex in the adult offspring, consistent with the well-documented mesolimbic dopaminergic and temporolimbic pathology in schizophrenia. These results suggest that prenatal poly I : C administration may provide a neurodevelopmental model of schizophrenia that reproduces a putative inducing factor; mimics the temporal course as well as some central abnormalities of the disorder; and predicts responsiveness to antipsychotic drugs. Neuropsychopharmacology (2003) 28, 1778-1789. advance online publication, 16 July 2003; doi:10.1038/sj.npp.1300248
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Affiliation(s)
- Lee Zuckerman
- Department of Psychology, Tel Aviv University, Tel Aviv, Israel
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40
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Weiner I. The "two-headed" latent inhibition model of schizophrenia: modeling positive and negative symptoms and their treatment. Psychopharmacology (Berl) 2003; 169:257-97. [PMID: 12601500 DOI: 10.1007/s00213-002-1313-x] [Citation(s) in RCA: 321] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2002] [Accepted: 10/16/2002] [Indexed: 01/24/2023]
Abstract
RATIONALE Latent inhibition (LI), namely, poorer performance on a learning task involving a previously pre-exposed non-reinforced stimulus, is disrupted in the rat by the dopamine (DA) releaser amphetamine which produces and exacerbates psychotic (positive) symptoms, and this is reversed by treatment with typical and atypical antipsychotic drugs (APDs) which on their own potentiate LI. These phenomena are paralleled by disrupted LI in normal amphetamine-treated humans, in high schizotypal humans, and in schizophrenia patients in the acute stages of the disorder, as well as by potentiated LI in normal humans treated with APDs. Consequently, disrupted LI is considered to provide an animal model of positive symptoms of schizophrenia with face, construct and predictive validity. OBJECTIVES To review most of the rodent data on the neural substrates of LI as well as on the effects of APDs on this phenomenon with an attempt to interpret and integrate these data within the framework of the switching model of LI; to show that there are two distinct LI models, disrupted and abnormally persistent LI; to relate these findings to the clinical condition. RESULTS The nucleus accumbens (NAC) and its DA innervation form a crucial component of the neural circuitry of LI, and are involved at the conditioning stage. There is a clear functional differentiation between the NAC shell and core subregions whereby damage to the shell disrupts LI and damage to the core renders LI abnormally persistent under conditions that disrupt LI in normal rats. The effects of shell and core lesions parallel those produced by lesions to the major sources of input to the NAC: entorhinal cortex lesion, like shell lesion, disrupts LI, whereas hippocampal lesion, like core lesion, produces persistent LI with changes in context, and basolateral amygdala (BLA) lesion, like core lesion, produces persistent LI with extended conditioning. Systemically induced blockade of glutamatergic as well as DA transmission produce persistent LI via effects exerted at the conditioning stage, whereas enhancement of DA transmission disrupts LI via effects at the conditioning stage. Serotonergic manipulations can disrupt or potentiate LI via effects at the pre-exposure stage. Both typical and atypical APDs potentiate LI via effects at conditioning whereas atypical APDs in addition disrupt LI via effects at pre-exposure. Schizophrenia patients can exhibit disrupted or normal LI as a function of the state of the disorder (acute versus chronic), as well as persistent LI. CONCLUSIONS Different drug and lesion manipulations produce two poles of abnormality in LI, namely, disrupted LI under conditions which lead to LI in normal rats, and abnormally persistent LI under conditions which disrupt it in normal rats. Disrupted and persistent LI are differentially responsive to APDs, with the former reversed by both typical and atypical APDs and the latter selectively reversed by atypical APDs. It is suggested that this "two-headed LI model" mimics two extremes of deficient cognitive switching seen in schizophrenia, excessive and retarded switching between associations, mediated by dysfunction of different brain circuitries, and can serve to model positive symptoms of schizophrenia and typical antipsychotic action, as well as negative symptoms of schizophrenia and atypical antipsychotic action.
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Affiliation(s)
- Ina Weiner
- Department of Psychology, Tel-Aviv University, Tel-Aviv, Israel.
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41
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Powell SB, Geyer MA. Developmental markers of psychiatric disorders as identified by sensorimotor gating. Neurotox Res 2002; 4:489-502. [PMID: 12754162 DOI: 10.1080/10298420290030578] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Prepulse inhibition (PPI) of the acoustic startle reflex is an operational measure of sensorimotor gating that is amenable to cross-species comparisons. Deficits in PPI have been repeatedly reported in patients with schizophrenia or other psychiatric disorders characterized by abnormalities in sensory, cognitive, or motor gating. Because some forms of schizophrenia appear to be attributable to early developmental perturbations, many animal studies have examined the influences of various developmental manipulations on PPI in adulthood. For example, isolation rearing of rats from weaning into adulthood leads to a reorganization of brain circuitry including changes in monoamine systems that modulate PPI. Isolation rearing of rats leads to deficits in PPI that are not evident pre-puberty, are enduring in adulthood, and are developmentally specific, in that isolation of adult rats does not affect PPI. The PPI deficits in isolation-reared rats are reversed by typical or atypical antipsychotic treatments, including raclopride, haloperidol, clozapine, olanzapine, quetiapine, and even the putative antipsychotic M100907. In contrast, other psychoactive drugs, such as chlordiazepoxide, diazepam, prazosin, or amitriptyline, do not normalize PPI in isolation-reared rats. Hence, the isolation-rearing model may help identify novel antipsychotics. Thus, social isolation rearing of rats provides a developmentally specific, non-pharmacological manipulation that leads to deficits in sensorimotor gating that mimic those observed in schizophrenia patients and are responsive to antipsychotic medications.
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Affiliation(s)
- Susan B. Powell
- Department of Psychiatry, University of California, 9500 Gilman Drive, 0804, La Jolla, San Diego, CA 92093, USA
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42
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Fiore M, Korf J, Antonelli A, Talamini L, Aloe L. Long-lasting effects of prenatal MAM treatment on water maze performance in rats: associations with altered brain development and neurotrophin levels. Neurotoxicol Teratol 2002; 24:179-91. [PMID: 11943506 DOI: 10.1016/s0892-0362(01)00214-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We previously reported that prenatal methylazoxymethanol (MAM) administered on days 11 and 12 of rat pregnancy induces structural changes in the cytoarchitecture of the hippocampal-entorhinal axis. We also showed that young and middle-aged prenatally treated MAM animals displayed changes in brain neurotrophin levels [Neurosci. Lett. 309 (2001) 113; Physiol. Behav. 71 (2000) 57.]. To continue this line of investigation, the working hypothesis adopted was that prenatal MAM administration, by interfering with limbic neurogenesis, could impair learning and memory ability of aged animals in the water maze. It was found that injection of MAM during early rat brain development induced deficits in both the acquisition and retention phases of the Morris maze. These behavioral changes were associated with significant changes in brain nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), reduced choline acetyltransferase (ChAT) immunoreactivity in forebrain cholinergic neurons and loss of neuropeptide Y (NPY) immunodistribution in cells of the entorhinal cortex. This finding, as well as confirming previous studies showing that injection of prenatal MAM administration induces significant changes in hippocampal-entorhinal axis neurogenesis and marked behavioral deficits in adult life, provides additional experimental evidence supporting the hypothesis that loss of NGF and/or BDNF-receptive or producing cells can co-occur at the onset of neurodevelopmental disorders.
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Affiliation(s)
- Marco Fiore
- Istituto di Neurobiologia e Medicina Molecolare, CNR, Viale Marx, 43/15, 00137 Rome, Italy
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43
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Fiore M, Aloe L, Westenbroek C, Amendola T, Antonelli A, Korf J. Bromodeoxyuridine and methylazoxymethanol exposure during brain development affects behavior in rats: consideration for a role of nerve growth factor and brain derived neurotrophic factor. Neurosci Lett 2001; 309:113-6. [PMID: 11502358 DOI: 10.1016/s0304-3940(01)02045-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rats prenatally exposed to the neurotoxins methylazoxymethanol (MAM) or 5-Bromo-2'-deoxyuridine (BrdU) are used as animal models of brain maldevelopment. We administered in rats MAM (20 mg/kg), or BrdU (100 mg/kg) or both at gestational day 11. Locomotion was not affected by any prenatal treatment whereas learning was delayed in the Morris maze in MAM animals. BrdU induced decreased NGF and BDNF levels in the hippocampus. In the parietal cortex prenatal BrdU administration induced NGF potentation associated with decreased BDNF. Animals treated with both MAM and BrdU showed also an increased immunopositivity for choline acetyltransferase (ChAT) and low affinity neurotrophins' receptor (p75) in the septum and Meynert's nuclei. These findings suggest that embryonic exposure to MAM and/or BrdU may be useful for studying mechanisms associated with neurodegenerative diseases affecting brain morphology and behavior.
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Affiliation(s)
- M Fiore
- Department of Biological Psychiatry, University of Groningen, Hanzeplein 1, 9713 EZ Groningen, The Netherlands
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44
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Rowley M, Bristow LJ, Hutson PH. Current and novel approaches to the drug treatment of schizophrenia. J Med Chem 2001; 44:477-501. [PMID: 11170639 DOI: 10.1021/jm0002432] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
MESH Headings
- Animals
- Antipsychotic Agents/adverse effects
- Antipsychotic Agents/pharmacology
- Antipsychotic Agents/therapeutic use
- Cholinergic Agonists/adverse effects
- Cholinergic Agonists/pharmacology
- Cholinergic Agonists/therapeutic use
- Disease Models, Animal
- Dopamine Antagonists/adverse effects
- Dopamine Antagonists/pharmacology
- Dopamine Antagonists/therapeutic use
- Enzyme Inhibitors/adverse effects
- Enzyme Inhibitors/pharmacology
- Enzyme Inhibitors/therapeutic use
- Excitatory Amino Acid Antagonists/adverse effects
- Excitatory Amino Acid Antagonists/pharmacology
- Excitatory Amino Acid Antagonists/therapeutic use
- Humans
- Mice
- Mice, Transgenic
- Nitric Oxide Synthase/antagonists & inhibitors
- Receptor, Serotonin, 5-HT2A
- Receptors, AMPA/antagonists & inhibitors
- Receptors, Dopamine D2/drug effects
- Receptors, Dopamine D4
- Receptors, Metabotropic Glutamate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, Neurotensin/agonists
- Receptors, Serotonin/drug effects
- Schizophrenia/drug therapy
- Schizophrenia/etiology
- Schizophrenia/metabolism
- Serotonin Antagonists/adverse effects
- Serotonin Antagonists/pharmacology
- Serotonin Antagonists/therapeutic use
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Affiliation(s)
- M Rowley
- Merck Sharp and Dohme, The Neuroscience Research Centre, Terlings Park, Eastwick Road, Harlow, Essex CM20 2QR, UK.
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Fiore M, Korf J, Angelucci F, Talamini L, Aloe L. Prenatal exposure to methylazoxymethanol acetate in the rat alters neurotrophin levels and behavior: considerations for neurodevelopmental diseases. Physiol Behav 2000; 71:57-67. [PMID: 11134686 DOI: 10.1016/s0031-9384(00)00310-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We did a single injection of methylazoxymethanol acetate (MAM) in pregnant rats on gestational day (GD) 11 or 12 to investigate the long-lasting effects of early entorhinal cortex (EC) and hippocampus maldevelopment on behavior, brain nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) levels, and the neurotrophin receptor p75 and choline acetyltransferase (ChAT) immunoreactivity. Adult animals treated with MAM had compromised EC development and showed changes in locomotion and displacement activities. In addition, rats treated on GD 12 had increased concentration of NGF and BDNF in the EC and hippocampus if compared to control rats. Prenatal MAM administration did not affect significantly p75 and ChAT distribution in the EC and septum. Results are discussed in reference to the neurodevelopmental hypothesis of psychiatric disorders.
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Affiliation(s)
- M Fiore
- Institute of Neurobiology, CNR, viale Marx, 43/15, 00137, Rome, Italy
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Bersani G, Iannitelli A, Fiore M, Angelucci F, Aloe L. Data and hypotheses on the role of nerve growth factor and other neurotrophins in psychiatric disorders. Med Hypotheses 2000; 55:199-207. [PMID: 10985909 DOI: 10.1054/mehy.1999.1044] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Nerve growth factor (NGF) was discovered and characterized for its role on the growth, differentiation and maintenance of specific neurons of the peripheral nervous system. Subsequent studies revealed that NGF is synthesized and released within the central nervous system and exerts a trophic and functional role on basal forebrain cholinergic neurons; it is involved in a protective role following brain insults induced by an epileptic status, seizure, as well as surgical and chemical lesions.More recently our collaborative studies provided evidence that NGF is implicated in neurobehavioral response including cerebral alterations associated with psychiatric disorders. In this brief review, ongoing and emerging data are presented and discussed.
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Affiliation(s)
- G Bersani
- 3rd Psychiatric Clinic, 'La Sapienza' University of Rome, Italy
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Aloe L, Iannitelli A, Angelucci F, Bersani G, Fiore M. Studies in animal models and humans suggesting a role of nerve growth factor in schizophrenia-like disorders. Behav Pharmacol 2000; 11:235-42. [PMID: 11103878 DOI: 10.1097/00008877-200006000-00007] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Neurotrophic factors, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), are known to play a crucial role in growth, differentiation and function in a variety of brain neurons during development and in adult life. We have recently shown that environmental changes, aggressive behavior and anxiety-like responses alter both circulating and brain basal NGF levels. In the present review, we present data obtained using animal models which suggest that neurotrophic factors, particularly NGF and BDNF, might be implicated in mechanism(s) leading to a condition associated with schizophrenic-like behaviors. The hypothesis that neurotrophins of the NGF family can be implicated in some maldevelopmental aspects of schizophrenia is supported by findings indicating that the constitutive levels of NGF and BDNF are affected in schizophrenic patients.
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Affiliation(s)
- L Aloe
- Institute of Neurobiology, CNR, Rome, Italy.
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Talamini LM, Ellenbroek B, Koch T, Korf J. Impaired sensory gating and attention in rats with developmental abnormalities of the mesocortex. Implications for schizophrenia. Ann N Y Acad Sci 2000; 911:486-94. [PMID: 10911899 DOI: 10.1111/j.1749-6632.2000.tb06751.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- L M Talamini
- Department of Psychiatry, University Hospital of Groningen, The Netherlands.
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Abstract
The entorhinal cortex, subiculum, and hippocampus have been regions of great interest in both clinical and neuropathological investigations of schizophrenia. Postmortem studies have identified numerous abnormalities, although many remain controversial or unconfirmed. Among the cellular and molecular neuropathological findings are (1) abnormal cytoarchitecture of the entorhinal cortex characterized by poorly formed layer II neuron clusters and laminar disorganization; (2) normal neuron density but smaller neuron size in the superficial lamina of the entorhinal cortex and subiculum; (3) abnormal expression of the microtubule-associated protein MAP2 in the entorhinal cortex and subiculum; (4) aberrant glutamatergic and catecholaminergic innervation of the entorhinal cortex; (5) abnormal mRNA expression of various transcription factors, ion channels, and neurosecretory pathway-related proteins in entorhinal stellate neurons; and (6) an absence of any neurodegeneration. Altogether, these findings suggest that aberrant neurodevelopmental processes play a key role in the pathobiology of schizophrenia and provide a neuroanatomic basis for understanding many of the clinical and neuropsychological abnormalities in the disorder.
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Affiliation(s)
- S E Arnold
- Department of Psychiatry, University of Pennsylvania, Philadelphia 19104, USA.
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Abstract
Negative or defect symptoms refer to a reduction in normal functioning. In schizophrenia, negative symptoms encompass, among others, anhedonia, flat affect, avolition and social withdrawal. These symptoms have been found to be particularly prominent in the more chronic phase of the illness and seem to be virtually insensitive to current antipsychotic treatment. This review focuses on the possibilities and limitations of animal models for the negative symptoms of schizophrenia. Following a review of the negative symptoms in schizophrenia, attention is focused on the two symptoms most often modelled in animals - anhedonia and social withdrawal. We then look at the important question of how to model schizophrenic pathology in animals. Since the exact pathology is still far from clear, most efforts have in the past concentrated on using psychotomimetic drugs such as amphetamine or phencyclidine. The recently accumulated knowledge that schizophrenia probably results from disturbances in the normal development of the brain has led to a surge of new animal models in which the long-term consequences of early manipulations are investigated. However, so far these models have predominantly concentrated on the positive rather than the negative symptoms of schizophrenia. The last part of this review is dedicated to the question of validation of animal models for anhedonia and social withdrawal. The general conclusion is that very few models have so far been adequately tested. The lack of currently effective treatment further hampers the study of such validation.
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Affiliation(s)
- B A Ellenbroek
- Department of Psychoneuropharmacology, University of Nijmegen, The Netherlands.
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