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Zhang Y, Wang S, Hei M. Maternal separation as early-life stress: Mechanisms of neuropsychiatric disorders and inspiration for neonatal care. Brain Res Bull 2024; 217:111058. [PMID: 39197670 DOI: 10.1016/j.brainresbull.2024.111058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 08/01/2024] [Accepted: 08/25/2024] [Indexed: 09/01/2024]
Abstract
The establishment of positive early parent-infant relationships provide essential nourishment and social stimulation for newborns. During the early stages of postnatal brain development, events such as synaptogenesis, neuronal maturation and glial differentiation occur in a highly coordinated manner. Maternal separation, as an early-life stress introducer, can disrupt the formation of parent-child bonds and exert long-term adverse effects throughout life. When offspring are exposed to maternal separation, the body regulates the stress of maternal separation through multiple mechanisms, including neuroinflammatory responses, neuroendocrinology, and neuronal electrical activity. In adulthood, early maternal separation has long-term effects, such as the induction of neuropsychiatric disorders such as anxiety, depression, and cognitive dysfunction. This review summarized the application of maternal separation models and the mechanisms of stress system response in neuropsychiatric disorders, serving as both a reminder and inspiration for approaches to improve neonatal care, "from bench to bedside".
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Affiliation(s)
- Yuan Zhang
- Neonatal Center, Beijing Children's Hospital Capital Medical University, National Center of Children's Health, Beijing 100045, China
| | - Shu Wang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
| | - Mingyan Hei
- Neonatal Center, Beijing Children's Hospital Capital Medical University, National Center of Children's Health, Beijing 100045, China.
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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: 32] [Impact Index Per Article: 10.7] [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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van Zyl PJ, Dimatelis JJ, Russell VA. Behavioural and biochemical changes in maternally separated Sprague-Dawley rats exposed to restraint stress. Metab Brain Dis 2016; 31:121-33. [PMID: 26555398 DOI: 10.1007/s11011-015-9757-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/27/2015] [Indexed: 01/26/2023]
Abstract
Early life adversity has been associated with the development of various neuropsychiatric disorders in adulthood such as depression and anxiety. The aim of this study was to determine if stress during adulthood can exaggerate the depression-/anxiety-like behaviour observed in the widely accepted maternally separated (MS) Sprague-Dawley (SD) rat model of depression. A further aim was to determine whether the behavioural changes were accompanied by changes in hippocampal brain-derived neurotrophic factor (BDNF) and the protein profile of the prefrontal cortex (PFC). Depression-/anxiety-like behaviour was measured in the elevated plus maze, open field and forced swim test (FST) in the MS SD rats exposed to chronic restraint stress in adulthood. As expected, MS increased immobility of SD rats in the FST but restraint stress did not enhance this effect of MS on SD rats. A proteomic analysis of the PFC revealed a decrease in actin-related proteins in MS and non-separated rats subjected to restraint stress as well as a decrease in mitochondrial energy-related proteins in the stressed rat groups. Since MS during early development causes a disruption in the hypothalamic-pituitary-adrenal axis and long-term changes in the response to subsequent stress, it may have prevented restraint stress from exerting its effects on behaviour. Moreover, the decrease in proteins related to mitochondrial energy metabolism in MS rats with or without subsequent restraint stress may be related to stress per se and not depression-like behaviour, because rats subjected to restraint stress displayed similar decreases in energy-related proteins and spent less time immobile in the FST than control rats.
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Affiliation(s)
- P J van Zyl
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, 7925, South Africa.
| | - J J Dimatelis
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, 7925, South Africa
| | - V A Russell
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, 7925, South Africa
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Möller M, Swanepoel T, Harvey BH. Neurodevelopmental Animal Models Reveal the Convergent Role of Neurotransmitter Systems, Inflammation, and Oxidative Stress as Biomarkers of Schizophrenia: Implications for Novel Drug Development. ACS Chem Neurosci 2015; 6:987-1016. [PMID: 25794269 DOI: 10.1021/cn5003368] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Schizophrenia is a life altering disease with a complex etiology and pathophysiology, and although antipsychotics are valuable in treating the disorder, certain symptoms and/or sufferers remain resistant to treatment. Our poor understanding of the underlying neuropathological mechanisms of schizophrenia hinders the discovery and development of improved pharmacological treatment, so that filling these gaps is of utmost importance for an improved outcome. A vast amount of clinical data has strongly implicated the role of inflammation and oxidative insults in the pathophysiology of schizophrenia. Preclinical studies using animal models are fundamental in our understanding of disease development and pathology as well as the discovery and development of novel treatment options. In particular, social isolation rearing (SIR) and pre- or postnatal inflammation (PPNI) have shown great promise in mimicking the biobehavioral manifestations of schizophrenia. Furthermore, the "dual-hit" hypothesis of schizophrenia states that a first adverse event such as genetic predisposition or a prenatal insult renders an individual susceptible to develop the disease, while a second insult (e.g., postnatal inflammation, environmental adversity, or drug abuse) may be necessary to precipitate the full-blown syndrome. Animal models that emphasize the "dual-hit" hypothesis therefore provide valuable insight into understanding disease progression. In this Review, we will discuss SIR, PPNI, as well as possible "dual-hit" animal models within the context of the redox-immune-inflammatory hypothesis of schizophrenia, correlating such changes with the recognized monoamine and behavioral alterations of schizophrenia. Finally, based on these models, we will review new therapeutic options, especially those targeting immune-inflammatory and redox pathways.
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Affiliation(s)
- M. Möller
- Department of Pharmacology and ‡Center of Excellence for Pharmaceutical Sciences,
School of Pharmacy, North-West University, Potchefstroom 2531, South Africa
| | - T. Swanepoel
- Department of Pharmacology and ‡Center of Excellence for Pharmaceutical Sciences,
School of Pharmacy, North-West University, Potchefstroom 2531, South Africa
| | - B. H. Harvey
- Department of Pharmacology and ‡Center of Excellence for Pharmaceutical Sciences,
School of Pharmacy, North-West University, Potchefstroom 2531, South Africa
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The effect of early environmental manipulation on locomotor sensitivity and methamphetamine conditioned place preference reward. Behav Brain Res 2014; 268:66-71. [PMID: 24713150 DOI: 10.1016/j.bbr.2014.03.045] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 03/25/2014] [Accepted: 03/29/2014] [Indexed: 11/20/2022]
Abstract
Early life stress leads to several effects on neurological development, affecting health and well-being later in life. Instances of child abuse and neglect are associated with higher rates of depression, risk taking behavior, and an increased risk of drug abuse later in life. This study used repeated neonatal separation of rat pups as a model of early life stress. Rat pups were either handled and weighed as controls or separated for 180 min per day during postnatal days 2-8. In adulthood, male and female rats were tested for methamphetamine conditioned place preference reward and methamphetamine induced locomotor activity. Tissue samples were collected and mRNA was quantified for the norepinephrine transporter in the prefrontal cortex and the dopamine transporter in the nucleus accumbens. Results indicated rats given methamphetamine formed a conditioned place preference, but there was no effect of early separation or sex. Separated males showed heightened methamphetamine-induced locomotor activity, but there was no effect of early separation for females. Overall females were more active than males in response to both saline and methamphetamine. No differences in mRNA levels were observed across any conditions. These results suggest early neonatal separation affects methamphetamine-induced locomotor activity in a sex-dependent manner but has no effects on methamphetamine conditioned place preference.
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Chronic Exposure to Light Reverses the Effect of Maternal Separation on Proteins in the Prefrontal Cortex. J Mol Neurosci 2013; 51:835-43. [DOI: 10.1007/s12031-013-0071-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
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Lewis CR, Staudinger K, Scheck L, Olive MF. The Effects of Maternal Separation on Adult Methamphetamine Self-Administration, Extinction, Reinstatement, and MeCP2 Immunoreactivity in the Nucleus Accumbens. Front Psychiatry 2013; 4:55. [PMID: 23785337 PMCID: PMC3683635 DOI: 10.3389/fpsyt.2013.00055] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 05/31/2013] [Indexed: 11/23/2022] Open
Abstract
The maternal separation (MS) paradigm is an animal model of early life stress. Animals subjected to MS during the first 2 weeks of life display altered behavioral and neuroendocrinological stress responses as adults. MS also produces altered responsiveness to and self-administration (SA) of various drugs of abuse including cocaine, ethanol, and amphetamine. However, no studies have yet examined the effects of MS on methamphetamine (METH) SA. This study was performed to examine the effects of MS on the acquisition of METH SA, extinction, and reinstatement of METH-seeking behavior in adulthood. Given the known influence of early life stress and drug exposure on epigenetic processes, we also investigated group differences in levels of the epigenetic marker methyl CpG binding protein 2 (MeCP2) in the nucleus accumbens (NAc) core. Long-Evans pups and dams were separated on postnatal days (PND) 2-14 for either 180 (MS180) or 15 min (MS15). Male offspring were allowed to acquire METH SA (0.05 mg/kg/infusion) in 15 2-h daily sessions starting at PND67, followed by extinction training and cue-induced reinstatement of METH-seeking behavior. Rats were then assessed for MeCP2 levels in the NAc core by immunohistochemistry. The MS180 group self-administered significantly more METH and acquired SA earlier than the MS15 group. No group differences in extinction or cue-induced reinstatement were observed. MS15 rats had significantly elevated MeCP2-immunoreactive cells in the NAc core as compared to MS180 rats. Together, these data suggest that MS has lasting influences on METH SA as well as epigenetic processes in the brain reward circuitry.
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Affiliation(s)
- Candace R Lewis
- Department of Psychology, Arizona State University Tempe, AZ, USA
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