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Guerrin CGJ, Doorduin J, Sommer IE, de Vries EFJ. The dual hit hypothesis of schizophrenia: Evidence from animal models. Neurosci Biobehav Rev 2021; 131:1150-1168. [PMID: 34715148 DOI: 10.1016/j.neubiorev.2021.10.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/21/2021] [Accepted: 10/24/2021] [Indexed: 12/16/2022]
Abstract
Schizophrenia is a heterogeneous psychiatric disorder, which can severely impact social and professional functioning. Epidemiological and clinical studies show that schizophrenia has a multifactorial aetiology comprising genetic and environmental risk factors. Although several risk factors have been identified, it is still not clear how they result in schizophrenia. This knowledge gap, however, can be investigated in animal studies. In this review, we summarise animal studies regarding molecular and cellular mechanisms through which genetic and environmental factors may affect brain development, ultimately causing schizophrenia. Preclinical studies suggest that early environmental risk factors can affect the immune, GABAergic, glutamatergic, or dopaminergic system and thus increase the susceptibility to another risk factor later in life. A second insult, like social isolation, stress, or drug abuse, can further disrupt these systems and the interactions between them, leading to behavioural abnormalities. Surprisingly, first insults like maternal infection and early maternal separation can also have protective effects. Single gene mutations associated with schizophrenia did not have a major impact on the susceptibility to subsequent environmental hits.
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Affiliation(s)
- Cyprien G J Guerrin
- Department of Nuclear Medicine and Medical Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Janine Doorduin
- Department of Nuclear Medicine and Medical Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Iris E Sommer
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Erik F J de Vries
- Department of Nuclear Medicine and Medical Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands.
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Developmental stress has sex-specific effects on contextual and cued fear conditioning in adulthood. Physiol Behav 2021; 231:113314. [PMID: 33417904 DOI: 10.1016/j.physbeh.2021.113314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 12/29/2020] [Accepted: 01/04/2021] [Indexed: 11/22/2022]
Abstract
Stress-induced deviations in central nervous system development has long-term effects on adult mental health. Previous research in humans demonstrates that prenatal or adolescent stress increases the risk for psychiatric disorders. Animal models investigating the effects of stress during prenatal or adolescent development produces behavioral outcomes analogous to those observed in humans. However, whether adolescent stress exposure potentiates the effects of prenatal stress is currently unknown. Thus, the current study tested whether adolescent stress increases the impact of prenatal stress on contextual and cued fear memory in adulthood. Male and female Sprague Dawley rats were exposed to a chronic variable stress schedule during the last week of gestation, during adolescence, or during both developmental periods before undergoing fear conditioning training in adulthood. Our hypothesis predicted that the combined effects of prenatal and adolescent stress on contextual and cued fear memory would be greater than the effects of stress during either time period alone. In contrast to our hypothesis, however, we found independent effects of prenatal and adolescent stress on contextual and cued fear memory in both sexes, with no additional combined impact of stress exposure during both developmental phases. In males, developmental stress increased freezing behavior during contextual and cued testing regardless of whether stress exposure was prenatal, adolescent, or combined prenatal and adolescent stress exposure. In contrast, the effects of developmental stress in females were both test- and ovarian hormone status-dependent. During cued testing, nonstressed female freezing behavior depended on estrous cycle phase, whereas freezing behavior in stressed females did not, suggesting that developmental stress interferes with hormone-dependent cued fear memory. No effects of developmental stress or estrous cycle phase were observed for contextual fear memory in females. The results of the current study suggest that the effects of prenatal and adolescent stress on contextual and cued fear memory are not cumulative, but the effects of developmental stress on associative memory differ between males and females.
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Ketharanathan T, Pereira A, Reets U, Walker D, Sundram S. Brain changes in NF-κB1 and epidermal growth factor system markers at peri-pubescence in the spiny mouse following maternal immune activation. Psychiatry Res 2021; 295:113564. [PMID: 33229121 DOI: 10.1016/j.psychres.2020.113564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 11/05/2020] [Indexed: 10/23/2022]
Abstract
Environmental risk factors that operate at foetal or neonatal levels increase the vulnerability to schizophrenia, plausibly via stress-immune activation that perturbs the epidermal growth factor (EGF) system, a system critical for neurodevelopment. We investigated potential associations between environmental insults and immune and EGF system changes through a maternal immune activation (MIA) model, using the precocial spiny mice (Acomys cahirinus). After mid-gestation MIA prepubescent offspring showed elevated NF-κB1 protein in nucleus accumbens, decreased EGFR in caudate putamen and a trend for increased PI3K-110δ in ventral hippocampus. Thus, prenatal stress may cause a heightened NF-κB1-mediated immune attenuation of EGF system signalling.
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Affiliation(s)
- Tharini Ketharanathan
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia.
| | - Avril Pereira
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia; Department of Psychiatry, University of Melbourne, Parkville, VIC 3052, Australia
| | - Udani Reets
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3168, Australia
| | - David Walker
- School of Health & Biomedical Sciences, RMIT University, Melbourne, VIC 3083, Australia
| | - Suresh Sundram
- Department of Psychiatry, Monash University, Clayton, VIC 3168, Australia
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Golofast B, Vales K. The connection between microbiome and schizophrenia. Neurosci Biobehav Rev 2019; 108:712-731. [PMID: 31821833 DOI: 10.1016/j.neubiorev.2019.12.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/01/2019] [Accepted: 12/06/2019] [Indexed: 12/15/2022]
Abstract
There has been an accumulation of knowledge about the human microbiome, some detailed investigations of the gastrointestinal microbiota and its functions, and the highlighting of complex interactions between the gut, the gut microbiota, and the central nervous system. That assumes the involvement of the microbiome in the pathogenesis of various CNS diseases, including schizophrenia. Given this information and the fact, that the gut microbiota is sensitive to internal and environmental influences, we have speculated that among the factors that influence the formation and composition of gut microbiota during life, possible key elements in the schizophrenia development chain are hidden where gut microbiota is a linking component. This article aims to describe and understand the developmental relationships between intestinal microbiota and the risk of developing schizophrenia.
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Affiliation(s)
- Bogdana Golofast
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Prague East, Czech Republic; Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague 10, Czech Republic.
| | - Karel Vales
- National Institute of Mental Health, Topolova 748, 250 67 Klecany, Prague East, Czech Republic
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Banqueri M, Martínez JA, Prieto MJ, Cid-Duarte S, Méndez M, Arias JL. Photobiomodulation rescues cognitive flexibility in early stressed subjects. Brain Res 2019; 1720:146300. [PMID: 31226326 DOI: 10.1016/j.brainres.2019.146300] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/10/2019] [Accepted: 06/17/2019] [Indexed: 12/17/2022]
Abstract
Neglectful parenting is one of the most prevalent forms of child mistreatment. This early life stress leads to long-term alterations in all the psychological domains, as well as brain alterations. Animal models have been developed to emulate and further study this early life stress, and one of most widely used models is maternal separation. In both human and animal models, cognitive flexibility has been found to be altered. In this study, we performed maternal separation (10 days, 4 h per day) in rats, and in adulthood, we tested their spatial navigation and cognitive flexibility. In addition, we delivered photobiomodulation treatment (Low-level light therapy: 1064 nm, 30 mW, 60 cycles) on the rats' brains, and we tested energy oxidative metabolism using cytochrome c oxidase histochemistry. Early life stress delivered in the form of maternal separation on the first 10 postnatal days leads to cognitive flexibility impairment and a general increase in energy metabolism in adulthood. Low-level light therapy seems to be useful for treating these unwanted outcomes, because it rescued cognitive flexibility and returned the oxidative energy metabolism to balanced scores, without harming controls' brains or behavior. Photobiomodulation is a promising tool in the treatment of chronic stress-related consequences because it rescued cognitive flexibility.
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Affiliation(s)
- María Banqueri
- Laboratory of Neuroscience, Department of Psychology, University of Oviedo, Plaza Feijoo, s/n, E-33003 Oviedo, Spain; Instituto de Neurociencias del Principado de Asturias (INEUROPA), Spain.
| | - Juan A Martínez
- Instituto de Neurociencias del Principado de Asturias (INEUROPA), Spain; Electronic Technology Area, University of Oviedo, Torres Quevedo Building (West), 2, Gijón, Spain
| | - Miguel J Prieto
- Instituto de Neurociencias del Principado de Asturias (INEUROPA), Spain; Electronic Technology Area, University of Oviedo, Torres Quevedo Building (West), 2, Gijón, Spain
| | - Sandra Cid-Duarte
- Laboratory of Neuroscience, Department of Psychology, University of Oviedo, Plaza Feijoo, s/n, E-33003 Oviedo, Spain
| | - Marta Méndez
- Laboratory of Neuroscience, Department of Psychology, University of Oviedo, Plaza Feijoo, s/n, E-33003 Oviedo, Spain; Instituto de Neurociencias del Principado de Asturias (INEUROPA), Spain; Electronic Technology Area, University of Oviedo, Torres Quevedo Building (West), 2, Gijón, Spain
| | - Jorge L Arias
- Laboratory of Neuroscience, Department of Psychology, University of Oviedo, Plaza Feijoo, s/n, E-33003 Oviedo, Spain; Instituto de Neurociencias del Principado de Asturias (INEUROPA), Spain
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Effects of early life stress on biochemical indicators of the dopaminergic system: A 3 level meta-analysis of rodent studies. Neurosci Biobehav Rev 2018; 95:1-16. [DOI: 10.1016/j.neubiorev.2018.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 09/03/2018] [Accepted: 09/05/2018] [Indexed: 12/31/2022]
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Khan A, Powell SB. Sensorimotor gating deficits in "two-hit" models of schizophrenia risk factors. Schizophr Res 2018; 198:68-83. [PMID: 29070440 PMCID: PMC5911431 DOI: 10.1016/j.schres.2017.10.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 10/03/2017] [Accepted: 10/06/2017] [Indexed: 02/07/2023]
Abstract
Genetic and environmental models of neuropsychiatric disease have grown exponentially over the last 20years. One measure that is often used to evaluate the translational relevance of these models to human neuropsychiatric disease is prepulse inhibition of startle (PPI), an operational measure of sensorimotor gating. Deficient PPI characterizes several neuropsychiatric disorders but has been most extensively studied in schizophrenia. It has become a useful tool in translational neuropharmacological and molecular genetics studies because it can be measured across species using almost the same experimental parameters. Although initial studies of PPI in rodents were pharmacological because of the robust predictive validity of PPI for antipsychotic efficacy, more recently, PPI has become standard common behavioral measures used in genetic and neurodevelopmental models of schizophrenia. Here we review "two hit" models of schizophrenia and discuss the utility of PPI as a tool in phenotyping these models of relevant risk factors. In the review, we consider approaches to rodent models of genetic and neurodevelopmental risk factors and selectively review "two hit" models of gene×environment and environment×environment interactions in which PPI has been measured.
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Affiliation(s)
- Asma Khan
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093, United States; Research Service, VA San Diego Healthcare System, La Jolla, CA, United States
| | - Susan B Powell
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093, United States; Research Service, VA San Diego Healthcare System, La Jolla, CA, United States.
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8
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Banqueri M, Méndez M, Arias JL. Behavioral effects in adolescence and early adulthood in two length models of maternal separation in male rats. Behav Brain Res 2017; 324:77-86. [DOI: 10.1016/j.bbr.2017.02.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/30/2017] [Accepted: 02/04/2017] [Indexed: 12/11/2022]
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van Bodegom M, Homberg JR, Henckens MJAG. Modulation of the Hypothalamic-Pituitary-Adrenal Axis by Early Life Stress Exposure. Front Cell Neurosci 2017; 11:87. [PMID: 28469557 PMCID: PMC5395581 DOI: 10.3389/fncel.2017.00087] [Citation(s) in RCA: 315] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/13/2017] [Indexed: 12/20/2022] Open
Abstract
Exposure to stress during critical periods in development can have severe long-term consequences, increasing overall risk on psychopathology. One of the key stress response systems mediating these long-term effects of stress is the hypothalamic-pituitary-adrenal (HPA) axis; a cascade of central and peripheral events resulting in the release of corticosteroids from the adrenal glands. Activation of the HPA-axis affects brain functioning to ensure a proper behavioral response to the stressor, but stress-induced (mal)adaptation of the HPA-axis' functional maturation may provide a mechanistic basis for the altered stress susceptibility later in life. Development of the HPA-axis and the brain regions involved in its regulation starts prenatally and continues after birth, and is protected by several mechanisms preventing corticosteroid over-exposure to the maturing brain. Nevertheless, early life stress (ELS) exposure has been reported to have numerous consequences on HPA-axis function in adulthood, affecting both its basal and stress-induced activity. According to the match/mismatch theory, encountering ELS prepares an organism for similar ("matching") adversities during adulthood, while a mismatching environment results in an increased susceptibility to psychopathology, indicating that ELS can exert either beneficial or disadvantageous effects depending on the environmental context. Here, we review studies investigating the mechanistic underpinnings of the ELS-induced alterations in the structural and functional development of the HPA-axis and its key external regulators (amygdala, hippocampus, and prefrontal cortex). The effects of ELS appear highly dependent on the developmental time window affected, the sex of the offspring, and the developmental stage at which effects are assessed. Albeit by distinct mechanisms, ELS induced by prenatal stressors, maternal separation, or the limited nesting model inducing fragmented maternal care, typically results in HPA-axis hyper-reactivity in adulthood, as also found in major depression. This hyper-activity is related to increased corticotrophin-releasing hormone signaling and impaired glucocorticoid receptor-mediated negative feedback. In contrast, initial evidence for HPA-axis hypo-reactivity is observed for early social deprivation, potentially reflecting the abnormal HPA-axis function as observed in post-traumatic stress disorder, and future studies should investigate its neural/neuroendocrine foundation in further detail. Interestingly, experiencing additional (chronic) stress in adulthood seems to normalize these alterations in HPA-axis function, supporting the match/mismatch theory.
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Affiliation(s)
| | | | - Marloes J. A. G. Henckens
- Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition and BehaviourRadboudumc, Nijmegen, Netherlands
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Long-Term Effects of Maternal Deprivation on Redox Regulation in Rat Brain: Involvement of NADPH Oxidase. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:7390516. [PMID: 28408971 PMCID: PMC5376945 DOI: 10.1155/2017/7390516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 02/23/2017] [Accepted: 03/01/2017] [Indexed: 01/16/2023]
Abstract
Maternal deprivation (MD) causes perinatal stress, with subsequent behavioral changes which resemble the symptoms of schizophrenia. The NADPH oxidase is one of the major generators of reactive oxygen species, known to play a role in stress response in different tissues. The aim of this study was to elucidate the long-term effects of MD on the expression of NADPH oxidase subunits (gp91phox, p22phox, p67phox, p47phox, and p40phox). Activities of cytochrome C oxidase and respiratory chain Complex I, as well as the oxidative stress parameters using appropriate spectrophotometric techniques were analyzed. Nine-day-old Wistar rats were exposed to a 24 h maternal deprivation and sacrificed at young adult age. The structures affected by perinatal stress, cortex, hippocampus, thalamus, and caudate nuclei were investigated. The most prominent findings were increased expressions of gp91phox in the cortex and hippocampus, increased expression of p22phox and p40phox, and decreased expression of gp91phox, p22phox, and p47phox in the caudate nuclei. Complex I activity was increased in all structures except cortex. Content of reduced glutathione was decreased in all sections while region-specific changes of other oxidative stress parameters were found. Our results indicate the presence of long-term redox alterations in MD rats.
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Early life stress and chronic variable stress in adulthood interact to influence methamphetamine self-administration in male rats. Behav Pharmacol 2016; 27:182-4. [PMID: 26176409 DOI: 10.1097/fbp.0000000000000166] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Early life stress interacts with adult stress to differentially modulate neural systems and vulnerability to various psychiatric illnesses. However, the effects of early life stress and adult stress on addictive behaviors have not been sufficiently investigated. We examined the effects of early life stress in the form of prolonged maternal separation, followed in early adulthood by either 10 days of chronic variable stress or no stress, on methamphetamine self-administration, extinction, and cue-induced reinstatement. We observed that chronic variable stress in adulthood reduced methamphetamine self-administration in rats with a history of early life stress. These findings add to an emerging body of literature suggesting interactions between early life and early adulthood stressors on adult behavioral phenotypes.
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Idrizi R, Malcolm P, Weickert CS, Zavitsanou K, Suresh Sundram. Striatal but not frontal cortical up-regulation of the epidermal growth factor receptor in rats exposed to immune activation in utero and cannabinoid treatment in adolescence. Psychiatry Res 2016; 240:260-264. [PMID: 27138815 DOI: 10.1016/j.psychres.2016.04.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 04/07/2016] [Accepted: 04/10/2016] [Indexed: 11/30/2022]
Abstract
In utero maternal immune activation (MIA) and cannabinoid exposure during adolescence constitute environmental risk factors for schizophrenia. We investigated these risk factors alone and in combination ("two-hit") on epidermal growth factor receptor (EGFR) and neuregulin-1 receptor (ErbB4) levels in the rat brain. EGFR but not ErbB4 receptor protein levels were significantly increased in the nucleus accumbens and striatum of "two-hit" rats only, with no changes seen at the mRNA level. These findings support region specific EGF-system dysregulation as a plausible mechanism in this animal model of schizophrenia pathogenesis.
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Affiliation(s)
- Rejhan Idrizi
- Molecular Psychopharmacology Laboratory, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.
| | - Peter Malcolm
- Molecular Psychopharmacology Laboratory, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.
| | - Cynthia Shannon Weickert
- NeuRA, Schizophrenia Research Institute, Randwick, New South Wales, Australia; School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia; Neuroscience Research Australia, Randwick, New South Wales, Australia.
| | - Katerina Zavitsanou
- NeuRA, Schizophrenia Research Institute, Randwick, New South Wales, Australia.
| | - Suresh Sundram
- Molecular Psychopharmacology Laboratory, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia; Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia; Northern Psychiatry Research Centre, Northern Area Mental Health Servic(f)e, Epping, Victoria, Australia.
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Impact of prenatal nicotine on the structure of midbrain dopamine regions in the rat. Brain Struct Funct 2015; 221:1939-53. [PMID: 25716298 DOI: 10.1007/s00429-015-1014-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 02/15/2015] [Indexed: 10/23/2022]
Abstract
In utero exposure of rats to nicotine (NIC) provides a useful animal model for studying the impact of smoking during pregnancy on human offspring. Certain sequelae of prenatal NIC exposure suggest an impact on the development of the midbrain dopamine (DA) system, which receives a robust cholinergic innervation from the mesopontine tegmentum. We therefore investigated whether prenatal NIC induced structural changes in cells and synapses within the midbrain that persisted into adulthood. Osmotic minipumps delivering either sodium bitartrate (vehicle; VEH) or NIC bitartrate at 2 mg/kg/day were implanted into nine timed-pregnant dams at E4. At birth, rat pups were culled to litters of six males each, and the litters were cross-fostered. Plasma levels of NIC and cotinine from killed pups provided evidence of NIC exposure in utero. Pups separated from dams at weaning showed a trend toward reduced locomotor activity at this time point but not when tested again in adulthood. Adult rats were killed for anatomical studies. Estimates of brain size and volume did not vary with NIC treatment. Midbrain sections stained for Nissl or by immunoperoxidase for tyrosine hydroxylase and analyzed using unbiased stereology revealed no changes in volume or cell number in the substantia nigra compacta or ventral tegmental area as a result of NIC exposure. Within the ventral tegmental area, electron microscopic physical disector analysis showed no significant differences in the number of axon terminals or the number of asymmetric (putative excitatory) or symmetric (putative inhibitory) synapses. Although too infrequent to estimate by unbiased stereology, no obvious difference in the proportion of cholinergic axons was noted in NIC- versus VEH-treated animals. These data suggest that activation of nicotinic receptors during prenatal development induces no significant modifications in the structure of cells in the ventral midbrain when assessed in adulthood.
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The maternal deprivation animal model revisited. Neurosci Biobehav Rev 2015; 51:151-63. [PMID: 25616179 DOI: 10.1016/j.neubiorev.2015.01.015] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 12/23/2014] [Accepted: 01/12/2015] [Indexed: 12/17/2022]
Abstract
Early life stress, in the form of MD (24h at pnd 9), interferes with brain developmental trajectories modifying both behavioral and neurobiochemical parameters. MD has been reported to enhance neuroendocrine responses to stress, to affect emotional behavior and to impair cognitive function. More recently, changes in body weight gain, metabolic parameters and immunological responding have also been described. Present data give support to the fact that neuronal degeneration and/or astrocyte proliferation are present in specific brain regions, mainly hippocampus, prefrontal cortex and hypothalamus, which are particularly vulnerable to the effects of neonatal stress. The MD animal model arises as a valuable tool for the investigation of the brain processes occurring at the narrow time window comprised between pnd 9 and 10 that are critical for the establishment of brain circuitries critical for the regulation of behavior, metabolism and energy homeostasis. In the present review we will discuss three possible mechanisms that might be crucial for the effects of MD, namely, the rapid increase in glucocorticoids, the lack of the neonatal leptin surge, and the enhanced endocannabinoid signaling during the specific critical period of MD. A better understanding of the mechanisms underlying the detrimental consequences of MD is a concern for public health and may provide new insights into mental health prevention strategies and into novel therapeutic approaches in neuropsychiatry.
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Abstract
Emerging literature implicates abnormalities in gamma frequency oscillations in the pathophysiology of schizophrenia, with hypofunction of N-methyl-D-aspartate (NMDA) receptors implicated as a key factor. Prepulse inhibition (PPI) is a behavioural measure of sensorimotor gating, which is disrupted in schizophrenia. We studied relationships between ongoing and sensory-evoked gamma oscillations and PPI using pharmacological interventions designed to increase gamma oscillations (ketamine, MK-801); reduce gamma oscillations (LY379268); or disrupt PPI (amphetamine). We predicted that elevating ongoing gamma power would lead to increased 'neural noise' in cortical circuits, dampened sensory-evoked gamma responses and disrupted behaviour. Wistar rats were implanted with EEG recording electrodes. They received ketamine (5 mg/kg), MK-801 (0.16 mg/kg), amphetamine (0.5 mg/kg), LY379268 (3 mg/kg) or vehicle and underwent PPI sessions with concurrent EEG recording. Ketamine and MK-801 increased the power of ongoing gamma oscillations and caused time-matched disruptions of PPI, while amphetamine marginally affected ongoing gamma power. In contrast, LY379268 reduced ongoing gamma power, but had no effect on PPI. The sensory gamma response evoked by the prepulse was reduced following treatment with all psychotomimetics, associating with disruptions in PPI. This was most noticeable following treatment with NMDA receptor antagonists. We found that ketamine and MK-801 increase ongoing gamma power and reduce evoked gamma power, both of which are related to disruptions in sensorimotor gating. This appears to be due to antagonism of NMDA receptors, since amphetamine and LY379268 differentially impacted these outcomes and possess different neuropharmacological substrates. Aberrant gamma frequency oscillations caused by NMDA receptor hypofunction may mediate the sensory processing deficits observed in schizophrenia.
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Comeau WL, Winstanley CA, Weinberg J. Prenatal alcohol exposure and adolescent stress - unmasking persistent attentional deficits in rats. Eur J Neurosci 2014; 40:3078-95. [PMID: 25059261 PMCID: PMC4189965 DOI: 10.1111/ejn.12671] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 06/13/2014] [Indexed: 02/07/2023]
Abstract
Prenatal alcohol exposure (PAE) can produce a myriad of deficits. Unfortunately, affected individuals may also be exposed to the stress of an adverse home environment, contributing to deficits of attentional processes that are the hallmark of optimal executive function. Male offspring of ad-libitum-fed Control (Con), Pairfed (PF), and PAE dams were randomly assigned to either a 5-day period of variable chronic mild stress (CMS) or no CMS in adolescence. In adulthood, rats were trained in a non-match to sample task (T-maze), followed by extensive assessment in the five-choice serial reaction time task. Once rats acquired the five-choice serial reaction time task (stable accuracy), they were tested in three challenge conditions: (i) increased sustained attention, (ii) selective attention and, (iii) varying doses of d-amphetamine, an indirect dopamine and norepinephrine agonist. At birth and throughout the study, PAE offspring showed reduced body weight. Moreover, although PAE animals were similar to Con animals in task acquisition, they were progressively less proficient with transitions to shorter stimulus durations (decreased accuracy and increased omissions). Five days of adolescent CMS increased basal corticosterone levels in adolescence and disrupted cognitive performance in adulthood. Further, CMS augmented PAE-related disturbances in acquisition and, to a lesser extent, also disrupted attentional processes in Con and PF animals. Following task acquisition, challenges unmasked persistent attentional difficulties resulting from both PAE and adolescent CMS. In conclusion, PAE, adolescent CMS, and their interaction produced unique behavioural profiles that suggest vulnerability in select neurobiological processes at different stages of development.
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Affiliation(s)
- Wendy L Comeau
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
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Gröger N, Bock J, Goehler D, Blume N, Lisson N, Poeggel G, Braun K. Stress in utero alters neonatal stress-induced regulation of the synaptic plasticity proteins Arc and Egr1 in a sex-specific manner. Brain Struct Funct 2014; 221:679-85. [PMID: 25239865 DOI: 10.1007/s00429-014-0889-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/09/2014] [Indexed: 12/23/2022]
Abstract
The present study in juvenile rats investigated a "two-hit model" to test the impact of prenatal stress exposure ("first hit") on the regulation of the synaptic plasticity immediate early genes Arc and Egr1 in response to a second neonatal stressor ("second hit") in a sex-specific manner. Three stress-exposed animal groups were compared at the age of 21 days in relation to unstressed controls (CON): preS animals were exposed to various unpredictable stressors during the last gestational trimester; postS animals were exposed to 45 min restraint stress at postnatal day 21, pre/postS animals were exposed to a combination of pre- and postnatal stress as described for the two previous groups. The postS and pre/postS groups were killed 2 h after exposure to the postnatal stressor, males and females were separately analyzed. In line with our hypothesis we detected sex-specific stress sensitivity for both analyzed proteins. Males did not show any significant changes in Arc expression irrespective of the stress condition. In contrast, females, which had been pre-exposed to prenatal stress, displayed an "amplified" Arc upregulation in response to postnatal stress (pre/postS group) compared to unstressed controls, which may reflect a "sensitization" effect of prenatal stress. For Egr1, the females did not show any stress-induced regulation irrespective of the stress condition, whereas in males, which were pre-exposed to prenatal stress, we observed a "protective" effect of prenatal stress on postnatal stress-induced downregulation of Egr1 expression (pre/postS group), which may indicate that prenatal stress exposure may induce "resilience".
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Affiliation(s)
- Nicole Gröger
- Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto von Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany.
| | - Joerg Bock
- Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto von Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Daniela Goehler
- Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto von Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Nicole Blume
- Institute for Biology, Human Biology, University of Leipzig, Talstraße 33, 04103, Leipzig, Germany
| | - Nicole Lisson
- Institute for Biology, Human Biology, University of Leipzig, Talstraße 33, 04103, Leipzig, Germany
| | - Gerd Poeggel
- Institute for Biology, Human Biology, University of Leipzig, Talstraße 33, 04103, Leipzig, Germany
| | - Katharina Braun
- Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto von Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
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Hill RA, Kiss Von Soly S, Ratnayake U, Klug M, Binder MD, Hannan AJ, van den Buuse M. Long-term effects of combined neonatal and adolescent stress on brain-derived neurotrophic factor and dopamine receptor expression in the rat forebrain. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2126-35. [PMID: 25159716 DOI: 10.1016/j.bbadis.2014.08.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 08/08/2014] [Accepted: 08/18/2014] [Indexed: 11/25/2022]
Abstract
Altered brain-derived neurotrophic factor (BDNF) signalling and dopaminergic neurotransmission have been shown in the forebrain in schizophrenia. The 'two hit' hypothesis proposes that two major disruptions during development are involved in the pathophysiology of this illness. We therefore used a 'two hit' rat model of combined neonatal and young-adult stress to assess effects on BDNF signalling and dopamine receptor expression. Wistar rats were exposed to neonatal maternal separation (MS) stress and/or adolescent/young-adult corticosterone (CORT) treatment. At adulthood the medial prefrontal cortex (mPFC), caudate putamen (CPu) and nucleus accumbens (NAc) were analysed by qPCR and Western blot. The 'two hit' combination of MS and CORT treatment caused significant increases in BDNF mRNA and protein levels in the mPFC of male, but not female rats. BDNF mRNA expression was unchanged in the CPu but was significantly reduced by CORT in the NAc. DR3 and DR2 mRNA were significantly up-regulated in the mPFC of two-hit rats and a positive correlation was found between BDNF and DR3 expression in male, but not female rats. DR2 and DR3 expression were significantly increased following CORT treatment in the NAc and a significant negative correlation between BDNF and DR3 and DR2 mRNA levels was found. Our data demonstrate male-specific two-hit effects of developmental stress on BDNF and DR3 expression in the mPFC. Furthermore, following chronic adolescent CORT treatment, the relationship between BDNF and dopamine receptor expression was significantly altered in the NAc. These results elucidate the long-term effects of 'two hit' developmental stress on behaviour.
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Affiliation(s)
- Rachel A Hill
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Szerenke Kiss Von Soly
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Udani Ratnayake
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Maren Klug
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; Department of Psychology, Swinburne University, Hawthorn, Australia
| | - Michele D Binder
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Maarten van den Buuse
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Australia; School of Psychological Science, La Trobe University, Melbourne, Australia.
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19
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Oswald LM, Wand GS, Kuwabara H, Wong DF, Zhu S, Brasic JR. History of childhood adversity is positively associated with ventral striatal dopamine responses to amphetamine. Psychopharmacology (Berl) 2014; 231:2417-33. [PMID: 24448898 PMCID: PMC4040334 DOI: 10.1007/s00213-013-3407-z] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 12/11/2013] [Indexed: 12/17/2022]
Abstract
RATIONALE Childhood exposure to severe or chronic trauma is an important risk factor for the later development of adult mental health problems, such as substance abuse. Even in nonclinical samples of healthy adults, persons with a history of significant childhood adversity seem to experience greater psychological distress than those without this history. Evidence from rodent studies suggests that early life stress may impair dopamine function in ways that increase risks for drug abuse. However, the degree to which these findings translate to other species remains unclear. OBJECTIVES This study was conducted to examine associations between childhood adversity and dopamine and subjective responses to amphetamine in humans. METHODS Following intake assessment, 28 healthy male and female adults, aged 18-29 years, underwent two consecutive 90-min positron emission tomography studies with high specific activity [(11)C]raclopride. The first scan was preceded by intravenous saline; the second by amphetamine (AMPH 0.3 mg/kg). RESULTS Consistent with prior literature, findings showed positive associations between childhood trauma and current levels of perceived stress. Moreover, greater number of traumatic events and higher levels of perceived stress were each associated with higher ventral striatal dopamine responses to AMPH. Findings of mediation analyses further showed that a portion of the relationship between childhood trauma and dopamine release may be mediated by perceived stress. CONCLUSIONS Overall, results are consistent with preclinical findings suggesting that early trauma may lead to enhanced sensitivity to psychostimulants and that this mechanism may underlie increased vulnerability for drug abuse.
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Affiliation(s)
- Lynn M. Oswald
- Department of Family and Community Health, University of Maryland School of Nursing, Baltimore, MD 21201, USA,Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Gary S. Wand
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hiroto Kuwabara
- Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Dean F. Wong
- Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Environmental Health Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shijun Zhu
- Department of Family and Community Health, University of Maryland School of Nursing, Baltimore, MD 21201, USA
| | - James R. Brasic
- Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Fuentes S, Daviu N, Gagliano H, Garrido P, Zelena D, Monasterio N, Armario A, Nadal R. Sex-dependent effects of an early life treatment in rats that increases maternal care: vulnerability or resilience? Front Behav Neurosci 2014; 8:56. [PMID: 24616673 PMCID: PMC3934416 DOI: 10.3389/fnbeh.2014.00056] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 02/05/2014] [Indexed: 11/13/2022] Open
Abstract
Early life stress (ELS) in rodents has profound long-term effects that are partially mediated by changes in maternal care. ELS not only induces “detrimental” effects in adulthood, increasing psychopathology, but also promotes resilience to further stressors. In Long-Evans rats, we evaluated a combination of two procedures as a model of ELS: restriction of bedding during the first post-natal days and exposure to a “substitute” mother. The maternal care of biological and “substitute” mothers was measured. The male and female offspring were evaluated during adulthood in several contexts. Anxiety was measured by the elevated plus-maze (EPM), acoustic startle response (ASR) and forced swim test (FST). In other group of animals, novelty-seeking was measured (activity in an inescapable novel environment, preference for novel environments and exploration of novel objects). Plasmatic ACTH and corticosterone in basal conditions and in response to stress were also measured. Cognitive impulsivity was assessed by a delay-discounting paradigm, and impulsive action, attention and compulsive-like behavior by a five choice serial reaction time task (5CSRTT). ELS decreased pup body weight and increased the care of the biological mother; however, the “substitute” mother did not exhibit overt maltreatment. A mixture of “detrimental” and “beneficial” effects was shown. In the 5CSRTT, attention was impaired in both genders, and in females, ELS increased compulsive-like behavior. Novel object exploration was only increased by ELS in males, but the preference for novel spaces decreased in both genders. Baseline anxiety (EPM and ASR) and recognition memory were not affected. Unexpectedly, ELS decreased the ACTH response to novelty and swim stress and increased active coping in the FST in both genders. Cognitive impulsivity was decreased only in females, but impulsive action was not affected. The enhancement in maternal care may “buffer” the effects of ELS in a context-dependent manner.
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Affiliation(s)
- Sílvia Fuentes
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Núria Daviu
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain ; Animal Physiology Unit, School of Biosciences, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Humberto Gagliano
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain ; Animal Physiology Unit, School of Biosciences, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Pedro Garrido
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Dóra Zelena
- Institute of Experimental Medicine, Hungarian Academy of Science Budapest, Hungary
| | - Nela Monasterio
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain ; Psychobiology Unit, School of Psychology, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Antonio Armario
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain ; Animal Physiology Unit, School of Biosciences, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Roser Nadal
- Institut de Neurociències, Universitat Autònoma de Barcelona Barcelona, Spain ; Psychobiology Unit, School of Psychology, Universitat Autònoma de Barcelona Barcelona, Spain
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21
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Lejeune S, Dourmap N, Martres MP, Giros B, Daugé V, Naudon L. The dopamine D1 receptor agonist SKF 38393 improves temporal order memory performance in maternally deprived rats. Neurobiol Learn Mem 2013; 106:268-73. [DOI: 10.1016/j.nlm.2013.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 10/11/2013] [Indexed: 10/26/2022]
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22
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Converse AK, Moore CF, Moirano JM, Ahlers EO, Larson JA, Engle JW, Barnhart TE, Murali D, Christian BT, DeJesus OT, Holden JE, Nickles RJ, Schneider ML. Prenatal stress induces increased striatal dopamine transporter binding in adult nonhuman primates. Biol Psychiatry 2013; 74:502-10. [PMID: 23726316 PMCID: PMC3775901 DOI: 10.1016/j.biopsych.2013.04.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 04/22/2013] [Accepted: 04/25/2013] [Indexed: 11/15/2022]
Abstract
BACKGROUND To determine the effects in adult offspring of maternal exposure to stress and alcohol during pregnancy, we imaged striatal and midbrain dopamine transporter (DAT) binding by positron emission tomography in rhesus monkeys (Macaca mulatta). We also evaluated the relationship between DAT binding and behavioral responses previously found to relate to dopamine D2 receptor density (responsivity to tactile stimuli, performance on a learning task, and behavior during a learning task). METHODS Subjects were adult offspring derived from a 2 × 2 experiment in which pregnant monkeys were randomly assigned to control, daily mild stress exposure (acoustic startle), voluntary consumption of moderate-level alcohol, or both daily stress and alcohol. Adult offspring (n = 38) were imaged by positron emission tomography with the DAT ligand [(18)F]2β-carbomethoxy-3β-(4-chlorophenyl)-8-(2-fluoroethyl)-nortropane ([(18)F]FECNT). RESULTS Results showed that prenatal stress yielded an overall increase of 15% in [(18)F]FECNT binding in the striatum (p = .016), 17% greater binding in the putamen (p = .012), and 13% greater binding in the head of the caudate (p = .028) relative to animals not exposed to prenatal stress. Striatal [(18)F]FECNT binding correlated negatively with habituation to repeated tactile stimulation and positively with tactile responsivity. There were no significant effects of prenatal alcohol exposure on [(18)F]FECNT binding. CONCLUSIONS Maternal exposure to mild daily stress during pregnancy yielded increases in striatal DAT availability that were apparent in adult offspring and were associated with behavioral characteristics reflecting tactile hyperresponsivity, a condition associated with problem behaviors in children.
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Affiliation(s)
- Alexander K. Converse
- Waisman Center, University of Wisconsin-Madison,Corresponding author: , tel. 001/608/265.6604, T123 Waisman Center, University of Wisconsin-Madison, Madison, WI 53704
| | | | | | | | - Julie A. Larson
- Harlow Center for Biological Psychology, University of Wisconsin-Madison,Department of Kinesiology, University of Wisconsin-Madison
| | | | | | | | | | | | - James E. Holden
- Department of Medical Physics, University of Wisconsin-Madison
| | | | - Mary L. Schneider
- Harlow Center for Biological Psychology, University of Wisconsin-Madison,Department of Psychology, University of Wisconsin-Madison,Department of Kinesiology, University of Wisconsin-Madison
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23
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Early maternal deprivation-induced modifications in the neurobiological, neurochemical and behavioral profile of adult rats. Behav Brain Res 2013; 244:29-37. [DOI: 10.1016/j.bbr.2013.01.040] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 01/11/2013] [Accepted: 01/15/2013] [Indexed: 01/14/2023]
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Ng E, McGirr A, Wong AHC, Roder JC. Using rodents to model schizophrenia and substance use comorbidity. Neurosci Biobehav Rev 2013; 37:896-910. [PMID: 23567519 DOI: 10.1016/j.neubiorev.2013.03.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/28/2013] [Accepted: 03/29/2013] [Indexed: 12/13/2022]
Abstract
Schizophrenia and substance use disorders (SUD) often occur together, yet it is unclear why this is the case or how best to manage dual diagnosis. Rodent models are well suited to study how genes and environment interact to impact neurodevelopment, brain function and behaviors relevant to dual diagnosis. Indeed a variety of rodent models for schizophrenia display behavioral and physiological features relevant to SUD including: neurodevelopmental models, models of a rare variant (Disc1), to models of common variants (neurexin, dysbindin and neuregulin), and models of various gene-drug interactions. Thus it may be worthwhile to probe models of schizophrenia for insights relevant to SUD and dual diagnosis. However, future studies on dual diagnosis should involve characterization beyond measuring locomotor responses to self-administration tasks, include drug classes other than psychostimulants, and dissect the neuroadaptations that underlie risk for dual diagnosis.
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Affiliation(s)
- Enoch Ng
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Room 860, Toronto, Ontario M5G 1X5, Canada.
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25
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Novak G, Fan T, O'Dowd BF, George SR. Postnatal maternal deprivation and pubertal stress have additive effects on dopamine D2 receptor and CaMKII beta expression in the striatum. Int J Dev Neurosci 2013; 31:189-95. [DOI: 10.1016/j.ijdevneu.2013.01.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/31/2012] [Accepted: 01/01/2013] [Indexed: 01/05/2023] Open
Affiliation(s)
- Gabriela Novak
- Centre for Addiction and Mental HealthTorontoOntarioCanada
- Department of PharmacologyUniversity of TorontoTorontoOntarioCanada
| | - Theresa Fan
- Centre for Addiction and Mental HealthTorontoOntarioCanada
| | - Brian F. O'Dowd
- Centre for Addiction and Mental HealthTorontoOntarioCanada
- Department of PharmacologyUniversity of TorontoTorontoOntarioCanada
| | - Susan R. George
- Centre for Addiction and Mental HealthTorontoOntarioCanada
- Department of PharmacologyUniversity of TorontoTorontoOntarioCanada
- Department of MedicineUniversity of TorontoTorontoOntarioCanada
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26
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Bilbo SD, Schwarz JM. The immune system and developmental programming of brain and behavior. Front Neuroendocrinol 2012; 33:267-86. [PMID: 22982535 PMCID: PMC3484177 DOI: 10.1016/j.yfrne.2012.08.006] [Citation(s) in RCA: 389] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 12/16/2022]
Abstract
The brain, endocrine, and immune systems are inextricably linked. Immune molecules have a powerful impact on neuroendocrine function, including hormone-behavior interactions, during health as well as sickness. Similarly, alterations in hormones, such as during stress, can powerfully impact immune function or reactivity. These functional shifts are evolved, adaptive responses that organize changes in behavior and mobilize immune resources, but can also lead to pathology or exacerbate disease if prolonged or exaggerated. The developing brain in particular is exquisitely sensitive to both endogenous and exogenous signals, and increasing evidence suggests the immune system has a critical role in brain development and associated behavioral outcomes for the life of the individual. Indeed, there are associations between many neuropsychiatric disorders and immune dysfunction, with a distinct etiology in neurodevelopment. The goal of this review is to describe the important role of the immune system during brain development, and to discuss some of the many ways in which immune activation during early brain development can affect the later-life outcomes of neural function, immune function, mood and cognition.
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Affiliation(s)
- Staci D Bilbo
- Department of Psychology and Neuroscience, Duke University, 572 Research Drive, Box 91050, Durham, NC 27708, USA.
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27
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Klug M, van den Buuse M. Chronic cannabinoid treatment during young adulthood induces sex-specific behavioural deficits in maternally separated rats. Behav Brain Res 2012; 233:305-13. [DOI: 10.1016/j.bbr.2012.05.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 05/04/2012] [Accepted: 05/08/2012] [Indexed: 01/07/2023]
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28
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Long-term behavioral and NMDA receptor effects of young-adult corticosterone treatment in BDNF heterozygous mice. Neurobiol Dis 2012; 46:722-31. [PMID: 22426399 DOI: 10.1016/j.nbd.2012.03.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/07/2012] [Accepted: 03/01/2012] [Indexed: 12/27/2022] Open
Abstract
Psychiatric illnesses, such as schizophrenia, are most likely caused by an interaction between genetic predisposition and environmental factors, including stress during development. The neurotrophin, brain-derived neurotrophic factor (BDNF) has been implicated in this illness as BDNF levels are decreased in the brain of patients with schizophrenia. The aim of the present study was to assess the combined effect of reduced BDNF levels and postnatal stress, simulated by chronic young-adult treatment with the stress hormone, corticosterone. From 6 weeks of age, female and male BDNF heterozygous mice and their wild-type controls were chronically treated with corticosterone in their drinking water for 3 weeks. At 11 weeks of age, male, but not female BDNF heterozygous mice treated with corticosterone exhibited a profound memory deficit in the Y-maze. There were no differences between the groups in baseline prepulse inhibition (PPI), a measure of sensorimotor gating, or its disruption by treatment with MK-801. However, an increase in startle caused by MK-801 treatment was absent in male, but not female BDNF heterozygous mice, irrespective of corticosterone treatment. Analysis of protein levels of the NMDA receptor subunits NR1, NR2A, NR2B and NR2C, showed a marked increase of NR2B levels in the dorsal hippocampus of male BDNF heterozygous mice treated with corticosterone. In the ventral hippocampus, significantly reduced levels of NR2A, NR2B and NR2C were observed in male BDNF heterozygous mice. The NMDA receptor effects in hippocampal sub-regions could be related to the spatial memory deficits and the loss of the effect of MK-801 on startle in these mice, respectively. No significant changes in NMDA receptor subunit levels were observed in any of the female groups. Similarly, no significant changes in levels of BDNF or its receptor, TrkB, were found other than the expected reduced levels of BDNF in heterozygous mice. In conclusion, the data show differential interactive effects of reduced levels of BDNF expression and corticosterone treatment on spatial memory and startle in male and female mice, accompanied by significant, but region-specific changes in NMDA receptor subunit levels in the dorsal and ventral hippocampus. These results could be important for our understanding of the interaction of neurodevelopmental stress and BDNF deficiency in cognitive and anxiety-related symptoms of psychiatric illnesses, such as schizophrenia.
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Daskalakis NP, Oitzl MS, Schächinger H, Champagne DL, de Kloet ER. Testing the cumulative stress and mismatch hypotheses of psychopathology in a rat model of early-life adversity. Physiol Behav 2012; 106:707-21. [PMID: 22306534 DOI: 10.1016/j.physbeh.2012.01.015] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/27/2011] [Accepted: 01/20/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND In the present study, we tested both the cumulative stress and the mismatch hypothesis of psychopathology. For this purpose the combined effects of early-life adversity and later-life stress exposure on behavioral markers of psychosis susceptibility were studied in male Wistar rats. METHOD Experiment I: rat pups divided on the basis of the levels of their maternal care experience in low, medium or high maternal care groups, were reared post-weaning in groups (Exp. IA) or in social isolation (Exp. IB) and tested at adulthood under basal conditions or after an acute corticosterone (CORT) administration. Maternal care levels were assessed by measuring the dam's licking and grooming (LG) the first postnatal week of life. Experiment II: rat pups exposed as neonates to daily sessions of 8h of maternal separation (MS) on postnatal days 3, 4 and 5 either altogether in their home cage (HOME SEP) or alone in a novel environment (NOVEL SEP), were reared post-weaning in groups and tested at adulthood under basal conditions. Adult testing included behaviors marking psychosis susceptibility: apomorphine-induced gnawing (APO-gnawing), acoustic startle response and its modulation by a prepulse stimulus (PPI). The behavior of the Medium LG offspring was used as baseline reference for all the three experiments. RESULTS Experiment I: Low maternal LG history alone had limited effects on the behavior of Wistar offspring, although increased acoustic startle and increased PPI, at high prepulse intensity levels, were observed. When low maternal LG history was combined with post-weaning social isolation, basal APO-gnawing was decreased and PPI increased, compared to High LG and Med LG offspring. This reflects attenuated psychosis susceptibility. High LG offspring reared in isolation displayed, however, the highest APO-gnawing and the lowest PPI levels among rats reared in social isolation, which is indicative for increased psychosis susceptibility. These findings support the mismatch hypothesis. For demonstration of the cumulative stress hypothesis an injection of CORT in the adult Low LG offspring was required that increased APO-gnawing and reduced PPI. This CORT-induced PPI disruption was greatly enhanced after additional isolation rearing. The High LG group, either socially housed or reared in isolation, was resistant to the acute effects of CORT at adulthood. Experiment II: MS increased psychosis susceptibility only in NOVEL SEP rats that had experienced MS in the context of early social isolation. These individuals displayed increased adult APO-gnawing and reduced PPI, if reared post-weaning in a condition that does not match with their early life social environment (i.e. group housing). This finding supports the mismatch hypothesis. CONCLUSION The outcome of environmental manipulations on developmental programming of psychosis susceptibility depends on the interplay of early-life adversity and later-life stressors in a manner that supports the mismatch hypothesis. However, evidence for the cumulative stress hypothesis arises if vulnerable individuals are exposed in later life additionally to excess of the stress hormone CORT.
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Affiliation(s)
- Nikolaos P Daskalakis
- Division of Medical Pharmacology, Leiden/Amsterdam Center for Drug Research, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
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30
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Nederhof E, Schmidt MV. Mismatch or cumulative stress: toward an integrated hypothesis of programming effects. Physiol Behav 2011; 106:691-700. [PMID: 22210393 DOI: 10.1016/j.physbeh.2011.12.008] [Citation(s) in RCA: 234] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 11/10/2011] [Accepted: 12/13/2011] [Indexed: 01/17/2023]
Abstract
This paper integrates the cumulative stress hypothesis with the mismatch hypothesis, taking into account individual differences in sensitivity to programming. According to the cumulative stress hypothesis, individuals are more likely to suffer from disease as adversity accumulates. According to the mismatch hypothesis, individuals are more likely to suffer from disease if a mismatch occurs between the early programming environment and the later adult environment. These seemingly contradicting hypotheses are integrated into a new model proposing that the cumulative stress hypothesis applies to individuals who were not or only to a small extent programmed by their early environment, while the mismatch hypothesis applies to individuals who experienced strong programming effects. Evidence for the main effects of adversity as well as evidence for the interaction between adversity in early and later life is presented from human observational studies and animal models. Next, convincing evidence for individual differences in sensitivity to programming is presented. We extensively discuss how our integrated model can be tested empirically in animal models and human studies, inviting researchers to test this model. Furthermore, this integrated model should tempt clinicians and other intervenors to interpret symptoms as possible adaptations from an evolutionary biology perspective.
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31
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Llorente-Berzal A, Fuentes S, Gagliano H, López-Gallardo M, Armario A, Viveros MP, Nadal R. Sex-dependent effects of maternal deprivation and adolescent cannabinoid treatment on adult rat behaviour. Addict Biol 2011; 16:624-37. [PMID: 21521421 DOI: 10.1111/j.1369-1600.2011.00318.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Early life experiences such as maternal deprivation (MD) exert long-lasting changes in adult behaviour and reactivity to stressors. Adolescent exposure to cannabinoids is a predisposing factor in developing certain psychiatric disorders. Therefore, the combination of the two factors could exacerbate the negative consequences of each factor when evaluated at adulthood. The objective of this study was to investigate the long-term effects of early MD [24 hours at postnatal day (PND) 9] and/or an adolescent chronic treatment with the cannabinoid agonist CP-55,940 (0.4 mg/kg, PND 28-42) on diverse behavioural and physiological responses of adult male and female Wistar rats. We tested them in the prepulse inhibition (PPI) of the startle response and analysed their exploratory activity (holeboard) and anxiety (elevated plus maze, EPM). In addition, we evaluated their adrenocortical reactivity in response to stress and plasma leptin levels. Maternal behaviour was measured before and after deprivation. MD induced a transient increase of maternal behaviour on reuniting. In adulthood, maternally deprived males showed anxiolytic-like behaviour (or increased risk-taking behaviour) in the EPM. Adolescent exposure to the cannabinoid agonist induced an impairment of the PPI in females and increased adrenocortical responsiveness to the PPI test in males. Both, MD and adolescent cannabinoid exposure also induced sex-dependent changes in plasma leptin levels and body weights. The present results indicate that early MD and adolescent cannabinoid exposure exerted distinct sex-dependent long-term behavioural and physiological modifications that could predispose to the development of certain neuropsychiatric disorders, though no synergistic effects were found.
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Affiliation(s)
- Alvaro Llorente-Berzal
- Department of Physiology, School of Biological Sciences, Complutense University, Madrid, Spain
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Adams W, van den Buuse M. Hippocampal serotonin depletion facilitates the enhancement of prepulse inhibition by risperidone: Possible role of 5-HT2C receptors in the dorsal hippocampus. Neuropharmacology 2011; 61:458-67. [DOI: 10.1016/j.neuropharm.2011.03.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 03/16/2011] [Accepted: 03/21/2011] [Indexed: 11/30/2022]
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van den Buuse M, Ruimschotel E, Martin S, Risbrough VB, Halberstadt AL. Enhanced effects of amphetamine but reduced effects of the hallucinogen, 5-MeO-DMT, on locomotor activity in 5-HT(1A) receptor knockout mice: implications for schizophrenia. Neuropharmacology 2011; 61:209-16. [PMID: 21501627 DOI: 10.1016/j.neuropharm.2011.04.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 03/29/2011] [Accepted: 04/01/2011] [Indexed: 01/15/2023]
Abstract
Serotonin-1A (5-HT(1A)) receptors may play a role in schizophrenia and the effects of certain antipsychotic drugs. However, the mechanism of interaction of 5-HT(1A) receptors with brain systems involved in schizophrenia, remains unclear. Here we show that 5-HT(1A) receptor knockout mice display enhanced locomotor hyperactivity to acute treatment with amphetamine, a widely used animal model of hyperdopaminergic mechanisms in psychosis. In contrast, the effect of MK-801 on locomotor activity, modeling NMDA receptor hypoactivity, was unchanged in the knockouts. The effect of the hallucinogen 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) was markedly reduced in 5-HT(1A) receptor knockout mice. There were no changes in apomorphine-induced disruption of PPI, a model of sensory gating deficits seen in schizophrenia. Similarly, there were no major changes in density of dopamine transporters (DAT) or dopamine D(1) or D(2) receptors which could explain the behavioural changes observed in 5-HT(1A) receptor knockout mice. These results extend our insight into the possible role of these receptors in aspects of schizophrenia. As also suggested by previous studies using agonist and antagonist drugs, 5-HT(1A) receptors may play an important role in hallucinations and to modulate dopaminergic activity in the brain.
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Affiliation(s)
- Maarten van den Buuse
- Behavioural Neuroscience Laboratory, Mental Health Research Institute, Parkville, Melbourne, Australia.
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Chen J, Wang Z, Li M. Multiple 'hits' during postnatal and early adulthood periods disrupt the normal development of sensorimotor gating ability in rats. J Psychopharmacol 2011; 25:379-92. [PMID: 20093319 DOI: 10.1177/0269881109354929] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study, we evaluated a multiple-hit animal model of schizophrenia in an attempt to capture the complex interactions among various adverse developmental factors in schizophrenia. Sprague-Dawley rats were assigned to receive either repeated daily 3-h maternal separation for eight days (first 'hit') on postnatal days (PND) 3 to 10, and/or avoidance conditioning for six days (second 'hit') on PND 49-56, and/or repeated phencyclidine treatment (third 'hit', 3.0 mg/kg, sc) immediately after each daily avoidance conditioning. Prepulse inhibition (PPI) of acoustic startle reflex was assessed at late adolescence (PND 41-43) and early adulthood (PND 62-63). The change in %PPI from the adolescence phase to adulthood phase was used to index the maturation-related improvement of sensorimotor gating ability. Maternal separation, avoidance conditioning and PCP treatment had a complex three-way interaction on the functional improvement of sensorimotor gating. Maternal separation impaired PPI improvement preferentially in the saline rats that were not subjected to avoidance conditioning. Avoidance conditioning had no effect on PPI improvement in the non-maternally separated rats, but restored the maternal separation-induced disruption. However, this restoration effect was abolished by PCP treatment. The present study also identified a number of behavioral, emotional and learning abnormalities caused by these three developmental insults which may precede their interactive disruption of normal development of sensorimotor gating ability.
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Affiliation(s)
- Jing Chen
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, PR China
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Bakshi VP, Alsene KM, Roseboom PH, Connors EE. Enduring sensorimotor gating abnormalities following predator exposure or corticotropin-releasing factor in rats: a model for PTSD-like information-processing deficits? Neuropharmacology 2011; 62:737-48. [PMID: 21288473 DOI: 10.1016/j.neuropharm.2011.01.040] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Revised: 01/23/2011] [Accepted: 01/24/2011] [Indexed: 01/21/2023]
Abstract
A deficit in prepulse inhibition (PPI) can be one of the clinically observed features of post-traumatic stress disorder (PTSD) that is seen long after the acute traumatic episode has terminated. Thus, reduced PPI may represent an enduring psychophysiological marker of this illness in some patients. PPI is an operational measure of sensorimotor gating and refers to the phenomenon in which a weak stimulus presented immediately before an intense startling stimulus inhibits the magnitude of the subsequent startle response. The effects of stress on PPI have been relatively understudied, and in particular, there is very little information on PPI effects of ethologically relevant psychological stressors. We aimed to develop a paradigm for evaluating stress-induced sensorimotor gating abnormalities by comparing the effects of a purely psychological stressor (predator exposure) to those of a nociceptive physical stressor (footshock) on PPI and baseline startle responses in rats over an extended period of time following stressor presentation. Male Sprague-Dawley rats were exposed (within a protective cage) to ferrets for 5 min or left in their homecage and then tested for PPI immediately, 24 h, 48 h, and 9 days after the exposure. The effects of footshock were evaluated in a separate set of rats. The effects seen with stressor presentation were compared to those elicited by corticotropin-releasing factor (CRF; 0.5 and 3 μg/6 μl, intracerebroventricularly). Finally, the effects of these stressors and CRF administration on plasma corticosterone were measured. PPI was disrupted 24 h after ferret exposure; in contrast, footshock failed to affect PPI at any time. CRF mimicked the predator stress profile, with the lowdose producing a PPI deficit 24 h after infusion. Interestingly, the high dose also produced a PPI deficit 24 h after infusion, but with this dose, the PPI deficit was evident even 9d later. Plasma corticosterone levels were elevated acutely (before PPI deficits emerged) by both stressors and CRF, but returned to normal control levels 24 h later, when PPI deficits were present. Thus, predator exposure produces a delayed disruption of PPI, and stimulation of CRF receptors recapitulates these effects. Contemporaneous HPA axis activation is neither necessary nor sufficient for these PPI deficits. These results indicate that predator exposure, perhaps acting through CRF, may model the delayed-onset and persistent sensorimotor gating abnormalities that have been observed clinically in PTSD, and that further studies using this model may shed insight on the mechanisms of information-processing deficits in this disorder. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Vaishali P Bakshi
- Department of Psychiatry and Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53719, USA.
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Jones NC, Martin S, Megatia I, Hakami T, Salzberg MR, Pinault D, Morris MJ, O'Brien TJ, van den Buuse M. A genetic epilepsy rat model displays endophenotypes of psychosis. Neurobiol Dis 2010; 39:116-25. [DOI: 10.1016/j.nbd.2010.02.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/21/2009] [Accepted: 02/03/2010] [Indexed: 12/22/2022] Open
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Coates JM, Gurnell M, Sarnyai Z. From molecule to market: steroid hormones and financial risk-taking. Philos Trans R Soc Lond B Biol Sci 2010; 365:331-43. [PMID: 20026470 DOI: 10.1098/rstb.2009.0193] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Little is known about the role of the endocrine system in financial decision-making. Here, we survey research on steroid hormones and their cognitive effects, and examine potential links to trader performance in the financial markets. Preliminary findings suggest that cortisol codes for risk and testosterone for reward. A key finding of this endocrine research is the different cognitive effects of acute versus chronic exposure to hormones: acutely elevated steroids may optimize performance on a range of tasks; but chronically elevated steroids may promote irrational risk-reward choices. We present a hypothesis suggesting that the irrational exuberance and pessimism observed during market bubbles and crashes may be mediated by steroid hormones. If hormones can exaggerate market moves, then perhaps the age and sex composition among traders and asset managers may affect the level of instability witnessed in the financial markets.
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Affiliation(s)
- John M Coates
- Judge Business School, University of Cambridge, Cambridge CB2 1AG, UK.
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Chavez C, Hollaus M, Scarr E, Pavey G, Gogos A, van den Buuse M. The effect of estrogen on dopamine and serotonin receptor and transporter levels in the brain: An autoradiography study. Brain Res 2010; 1321:51-9. [DOI: 10.1016/j.brainres.2009.12.093] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 12/15/2009] [Accepted: 12/16/2009] [Indexed: 11/15/2022]
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Meyer U, Feldon J. Epidemiology-driven neurodevelopmental animal models of schizophrenia. Prog Neurobiol 2010; 90:285-326. [DOI: 10.1016/j.pneurobio.2009.10.018] [Citation(s) in RCA: 261] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/30/2009] [Accepted: 10/14/2009] [Indexed: 12/17/2022]
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Neuregulin 1 hypomorphic mutant mice: enhanced baseline locomotor activity but normal psychotropic drug-induced hyperlocomotion and prepulse inhibition regulation. Int J Neuropsychopharmacol 2009; 12:1383-93. [PMID: 19400983 DOI: 10.1017/s1461145709000388] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuregulin 1 (Nrg1) has been widely recognized as a candidate gene for schizophrenia. This study therefore investigated mice heterozygous for a mutation in the transmembrane domain of this trophic factor (Nrg1+/- mice) in a number of behavioural test systems with relevance to schizophrenia, including psychotropic drug-induced locomotor hyperactivity and prepulse inhibition (PPI) of startle. Baseline locomotor activity in the open field or in photocell cages was slightly, but significantly enhanced in Nrg1+/- mice compared to wild-type littermate controls at age 12-16 wk, but not at age 6 months. The ability of amphetamine, phencyclidine (PCP) or MK-801 to induce locomotor hyperactivity was not significantly different between the genotypes. There was no difference in baseline PPI, startle or startle habituation and there was no difference in the effect of apomorphine, amphetamine or MK-801 on any of these parameters. Only treatment with the 5-HT1A receptor agonist 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) showed a differential effect between genotypes, with a disruption of PPI occurring in Nrg1+/- mice compared to no effect in wild-type controls. This treatment also induced a significant reduction of startle which could have influenced the result. The density of dopamine D2 receptors in the forebrain and of 5-HT1A receptors in the hippocampus and raphe nuclei was not different between Nrg1+/- mice and controls. These studies add to the knowledge about behavioural effects in this mouse model of impaired Nrg1 function and suggest that a number of the behavioural tests with relevance to schizophrenia are normal in these mice.
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Psychotropic drug-induced locomotor hyperactivity and prepulse inhibition regulation in male and female aromatase knockout (ArKO) mice: role of dopamine D1 and D2 receptors and dopamine transporters. Psychopharmacology (Berl) 2009; 206:267-79. [PMID: 19597801 DOI: 10.1007/s00213-009-1604-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 06/24/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE AND OBJECTIVES The aim of the present study was to investigate the possible role of oestrogen in schizophrenia by comparing aromatase knockout (ArKO) mice, which are unable to produce oestrogen, with wild-type controls using two behavioural animal models with relevance to the illness, psychotropic drug-induced locomotor hyperactivity and prepulse inhibition (PPI). RESULTS Baseline PPI was not different between ArKO and controls. Treatment with apomorphine, MK-801 and amphetamine caused disruption of PPI in all groups. However, in female but not male ArKO mice, the effect of both apomorphine and amphetamine was reduced. In female ArKO mice, amphetamine-induced hyperlocomotion was markedly reduced, but in male mice, the genotype difference was far smaller. Female but not male ArKO mice also showed a reduction of phencyclidine-induced locomotor hyperactivity. The density of dopamine transporters, but not D1 and D2 receptors, was significantly increased in the caudate putamen of male but not female ArKO mice compared to wild-type mice. This could represent a compensatory dopaminergic upregulation in male ArKO mice. CONCLUSION Because of their lack of oestrogen production, it was anticipated that ArKO mice would display enhanced effects of amphetamine on locomotor activity and PPI. Instead, in these animals, aromatase knockout appeared to be 'protective'. This may represent limitations in the ability to model a complex illness such as schizophrenia in a constitutive knockout model, such as ArKO mice. Moreover, the current results may point at the involvement of other sex steroids, which are also altered in ArKO mice, in dopaminergic control of behaviour.
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Bilbo SD, Schwarz JM. Early-life programming of later-life brain and behavior: a critical role for the immune system. Front Behav Neurosci 2009; 3:14. [PMID: 19738918 PMCID: PMC2737431 DOI: 10.3389/neuro.08.014.2009] [Citation(s) in RCA: 448] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 07/22/2009] [Indexed: 12/12/2022] Open
Abstract
The immune system is well characterized for its critical role in host defense. Far beyond this limited role however, there is mounting evidence for the vital role the immune system plays within the brain, in both normal, “homeostatic” processes (e.g., sleep, metabolism, memory), as well as in pathology, when the dysregulation of immune molecules may occur. This recognition is especially critical in the area of brain development. Microglia and astrocytes, the primary immunocompetent cells of the CNS, are involved in every major aspect of brain development and function, including synaptogenesis, apoptosis, and angiogenesis. Cytokines such as tumor necrosis factor (TNF)α, interleukin [IL]-1β, and IL-6 are produced by glia within the CNS, and are implicated in synaptic formation and scaling, long-term potentiation, and neurogenesis. Importantly, cytokines are involved in both injury and repair, and the conditions underlying these distinct outcomes are under intense investigation and debate. Evidence from both animal and human studies implicates the immune system in a number of disorders with known or suspected developmental origins, including schizophrenia, anxiety/depression, and cognitive dysfunction. We review the evidence that infection during the perinatal period of life acts as a vulnerability factor for later-life alterations in cytokine production, and marked changes in cognitive and affective behaviors throughout the remainder of the lifespan. We also discuss the hypothesis that long-term changes in brain glial cell function underlie this vulnerability.
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Affiliation(s)
- Staci D Bilbo
- Department of Psychology & Neuroscience, Duke University Durham, NC, USA.
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