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Schmitt A, Malchow B, Hasan A, Falkai P. The impact of environmental factors in severe psychiatric disorders. Front Neurosci 2014; 8:19. [PMID: 24574956 PMCID: PMC3920481 DOI: 10.3389/fnins.2014.00019] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 01/23/2014] [Indexed: 01/08/2023] Open
Abstract
During the last decades, schizophrenia has been regarded as a developmental disorder. The neurodevelopmental hypothesis proposes schizophrenia to be related to genetic and environmental factors leading to abnormal brain development during the pre- or postnatal period. First disease symptoms appear in early adulthood during the synaptic pruning and myelination process. Meta-analyses of structural MRI studies revealing hippocampal volume deficits in first-episode patients and in the longitudinal disease course confirm this hypothesis. Apart from the influence of risk genes in severe psychiatric disorders, environmental factors may also impact brain development during the perinatal period. Several environmental factors such as antenatal maternal virus infections, obstetric complications entailing hypoxia as common factor or stress during neurodevelopment have been identified to play a role in schizophrenia and bipolar disorder, possibly contributing to smaller hippocampal volumes. In major depression, psychosocial stress during the perinatal period or in adulthood is an important trigger. In animal studies, chronic stress or repeated administration of glucocorticoids have been shown to induce degeneration of glucocorticoid-sensitive hippocampal neurons and may contribute to the pathophysiology of affective disorders. Epigenetic mechanisms altering the chromatin structure such as histone acetylation and DNA methylation may mediate effects of environmental factors to transcriptional regulation of specific genes and be a prominent factor in gene-environmental interaction. In animal models, gene-environmental interaction should be investigated more intensely to unravel pathophysiological mechanisms. These findings may lead to new therapeutic strategies influencing epigenetic targets in severe psychiatric disorders.
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Affiliation(s)
- Andrea Schmitt
- Department of Psychiatry and Psychotherapy, LMU Munich Munich, Germany ; Laboratory of Neuroscience (LIM27), Institute of Psychiatry, University of Sao Paulo São Paulo, Brazil
| | - Berend Malchow
- Department of Psychiatry and Psychotherapy, LMU Munich Munich, Germany
| | - Alkomiet Hasan
- Department of Psychiatry and Psychotherapy, LMU Munich Munich, Germany
| | - Peter Falkai
- Department of Psychiatry and Psychotherapy, LMU Munich Munich, Germany
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Babic S, Jezova D. Effect of phenytoin treatment on cell proliferation in the hippocampus and the heart and related neuroendocrine changes under non-stress and stress conditions. Neurol Res 2013; 36:112-7. [DOI: 10.1179/1743132813y.0000000278] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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53
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Shih PC, Yang YR, Wang RY. Effects of exercise intensity on spatial memory performance and hippocampal synaptic plasticity in transient brain ischemic rats. PLoS One 2013; 8:e78163. [PMID: 24205142 PMCID: PMC3808358 DOI: 10.1371/journal.pone.0078163] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 09/17/2013] [Indexed: 12/17/2022] Open
Abstract
Memory impairment is commonly noted in stroke survivors, and can lead to delay of functional recovery. Exercise has been proved to improve memory in adult healthy subjects. Such beneficial effects are often suggested to relate to hippocampal synaptic plasticity, which is important for memory processing. Previous evidence showed that in normal rats, low intensity exercise can improve synaptic plasticity better than high intensity exercise. However, the effects of exercise intensities on hippocampal synaptic plasticity and spatial memory after brain ischemia remain unclear. In this study, we investigated such effects in brain ischemic rats. The middle cerebral artery occlusion (MCAO) procedure was used to induce brain ischemia. After the MCAO procedure, rats were randomly assigned to sedentary (Sed), low-intensity exercise (Low-Ex), or high-intensity exercise (High-Ex) group. Treadmill training began from the second day post MCAO procedure, 30 min/day for 14 consecutive days for the exercise groups. The Low-Ex group was trained at the speed of 8 m/min, while the High-Ex group at the speed of 20 m/min. The spatial memory, hippocampal brain-derived neurotrophic factor (BDNF), synapsin-I, postsynaptic density protein 95 (PSD-95), and dendritic structures were examined to document the effects. Serum corticosterone level was also quantified as stress marker. Our results showed the Low-Ex group, but not the High-Ex group, demonstrated better spatial memory performance than the Sed group. Dendritic complexity and the levels of BDNF and PSD-95 increased significantly only in the Low-Ex group as compared with the Sed group in bilateral hippocampus. Notably, increased level of corticosterone was found in the High-Ex group, implicating higher stress response. In conclusion, after brain ischemia, low intensity exercise may result in better synaptic plasticity and spatial memory performance than high intensity exercise; therefore, the intensity is suggested to be considered during exercise training.
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Affiliation(s)
- Pei-Cheng Shih
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
- Department of Physical Therapy, Mackay Memorial Hospital, Taipei, Taiwan
| | - Yea-Ru Yang
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
| | - Ray-Yau Wang
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
- * E-mail:
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Karabeg MM, Grauthoff S, Kollert SY, Weidner M, Heiming RS, Jansen F, Popp S, Kaiser S, Lesch KP, Sachser N, Schmitt AG, Lewejohann L. 5-HTT deficiency affects neuroplasticity and increases stress sensitivity resulting in altered spatial learning performance in the Morris water maze but not in the Barnes maze. PLoS One 2013; 8:e78238. [PMID: 24167611 PMCID: PMC3805519 DOI: 10.1371/journal.pone.0078238] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/11/2013] [Indexed: 12/20/2022] Open
Abstract
The purpose of this study was to evaluate whether spatial hippocampus-dependent learning is affected by the serotonergic system and stress. Therefore, 5-HTT knockout (-/-), heterozygous (+/-) and wildtype (+/+) mice were subjected to the Barnes maze (BM) and the Morris water maze (WM), the latter being discussed as more aversive. Additionally, immediate early gene (IEG) expression, hippocampal adult neurogenesis (aN), and blood plasma corticosterone were analyzed. While the performance of 5-HTT-/- mice in the BM was undistinguishable from both other genotypes, they performed worse in the WM. However, in the course of the repeated WM trials 5-HTT-/- mice advanced to wildtype level. The experience of a single trial of either the WM or the BM resulted in increased plasma corticosterone levels in all genotypes. After several trials 5-HTT-/- mice exhibited higher corticosterone concentrations compared with both other genotypes in both tests. Corticosterone levels were highest in 5-HTT-/- mice tested in the WM indicating greater aversiveness of the WM and a greater stress sensitivity of 5-HTT deficient mice. Quantitative immunohistochemistry in the hippocampus revealed increased cell counts positive for the IEG products cFos and Arc as well as for proliferation marker Ki67 and immature neuron marker NeuroD in 5-HTT-/- mice compared to 5-HTT+/+ mice, irrespective of the test. Most differences were found in the suprapyramidal blade of the dentate gyrus of the septal hippocampus. Ki67-immunohistochemistry revealed a genotype x environment interaction with 5-HTT genotype differences in naïve controls and WM experience exclusively yielding more Ki67-positive cells in 5-HTT+/+ mice. Moreover, in 5-HTT-/- mice we demonstrate that learning performance correlates with the extent of aN. Overall, higher baseline IEG expression and increased an in the hippocampus of 5-HTT-/- mice together with increased stress sensitivity may constitute the neurobiological correlate of raised alertness, possibly impeding optimal learning performance in the more stressful WM.
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Affiliation(s)
- Margherita M. Karabeg
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Sandra Grauthoff
- Department of Behavioral Biology, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Sina Y. Kollert
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Magdalena Weidner
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Rebecca S. Heiming
- Department of Behavioral Biology, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Friederike Jansen
- Department of Behavioral Biology, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Sandy Popp
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Sylvia Kaiser
- Department of Behavioral Biology, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Norbert Sachser
- Department of Behavioral Biology, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Angelika G. Schmitt
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
- * E-mail:
| | - Lars Lewejohann
- Department of Behavioral Biology, University of Münster, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
- Behavioural Biology, University of Osnabrück, Osnabrück, Germany
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55
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Osborn M, Rustom N, Clarke M, Litteljohn D, Rudyk C, Anisman H, Hayley S. Antidepressant-like effects of erythropoietin: a focus on behavioural and hippocampal processes. PLoS One 2013; 8:e72813. [PMID: 24019878 PMCID: PMC3760922 DOI: 10.1371/journal.pone.0072813] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 07/19/2013] [Indexed: 12/11/2022] Open
Abstract
Depression is a chronic and debilitating condition with a significant degree of relapse and treatment resistance that could stem, at least in part, from disturbances of neuroplasticity. This has led to an increased focus on treatment strategies that target brain derived neurotrophic factor (BDNF), synaptic plasticity and adult neurogenesis. In the current study we aimed to assess whether erythropoietin (EPO) would have antidepressant-like effects given its already established pro-trophic actions. In particular, we assessed whether EPO would diminish the deleterious effects of a social stressor in mice. Indeed, EPO induced anxiolytic and antidepressant-like responses in a forced swim test, open field, elevated-plus maze, and a novelty test, and appeared to blunt some of the negative behavioural effects of a social stressor. Furthermore, EPO promoted adult hippocampal neurogenesis, an important feature of effective antidepressants. Finally, a separate study using the mTOR inhibitor rapamycin revealed that antagonizing this pathway prevented the impact of EPO upon forced swim performance. These data are consistent with previous findings showing that the mTOR pathway and its neurogenic and synaptogenic effects might mediate the behavioral consequences of antidepressant agents. Our findings further highlight EPO as a possible adjunct treatment for affective disorders, as well as other stressor associated disorders of impaired neuroplasticity.
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Affiliation(s)
- Meagan Osborn
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Nazneen Rustom
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Melanie Clarke
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Darcy Litteljohn
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Chris Rudyk
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Hymie Anisman
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Shawn Hayley
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
- * E-mail:
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56
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Ikeno T, Weil ZM, Nelson RJ. Photoperiod affects the diurnal rhythm of hippocampal neuronal morphology of siberian hamsters. Chronobiol Int 2013; 30:1089-100. [DOI: 10.3109/07420528.2013.800090] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Zoladz PR, Fleshner M, Diamond DM. Differential effectiveness of tianeptine, clonidine and amitriptyline in blocking traumatic memory expression, anxiety and hypertension in an animal model of PTSD. Prog Neuropsychopharmacol Biol Psychiatry 2013; 44:1-16. [PMID: 23318688 DOI: 10.1016/j.pnpbp.2013.01.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 12/22/2012] [Accepted: 01/04/2013] [Indexed: 12/21/2022]
Abstract
Individuals exposed to life-threatening trauma are at risk for developing post-traumatic stress disorder (PTSD), a debilitating condition that involves persistent anxiety, intrusive memories and several physiological disturbances. Current pharmacotherapies for PTSD manage only a subset of these symptoms and typically have adverse side effects which limit their overall effectiveness. We evaluated the effectiveness of three different pharmacological agents to ameliorate a broad range of PTSD-like symptoms in our established predator-based animal model of PTSD. Adult male Sprague-Dawley rats were given 1-h cat exposures on two occasions that were separated by 10 days, in conjunction with chronic social instability. Beginning 24 h after the first cat exposure, rats received daily injections of amitriptyline, clonidine, tianeptine or vehicle. Three weeks after the second cat exposure, all rats underwent a battery of behavioral and physiological tests. The vehicle-treated, psychosocially stressed rats demonstrated a robust fear memory for the two cat exposures, as well as increased anxiety expressed on the elevated plus maze, an exaggerated startle response, elevated heart rate and blood pressure, reduced growth rate and increased adrenal gland weight, relative to the vehicle-treated, non-stressed (control) rats. Neither amitriptyline nor clonidine was effective at blocking the entire cluster of stress-induced sequelae, and each agent produced adverse side effects in control subjects. Only the antidepressant tianeptine completely blocked the effects of psychosocial stress on all of the physiological and behavioral measures that were examined. These findings illustrate the differential effectiveness of these three treatments to block components of PTSD-like symptoms in rats, and in particular, reveal the profile of tianeptine as the most effective of all three agents.
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Affiliation(s)
- Phillip R Zoladz
- Department of Psychology, Sociology & Criminal Justice, Ohio Northern University, Ada, OH, USA
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58
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Pérez MÁ, Terreros G, Dagnino-Subiabre A. Long-term ω-3 fatty acid supplementation induces anti-stress effects and improves learning in rats. BEHAVIORAL AND BRAIN FUNCTIONS : BBF 2013; 9:25. [PMID: 23768007 PMCID: PMC3687561 DOI: 10.1186/1744-9081-9-25] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 06/07/2013] [Indexed: 01/18/2023]
Abstract
Chronic stress leads to secretion of the adrenal steroid hormone corticosterone, inducing hippocampal atrophy and dendritic hypertrophy in the rat amygdala. Both alterations have been correlated with memory impairment and increased anxiety. Supplementation with ω-3 fatty acids improves memory and learning in rats. The aim of this study was to evaluate the effects of ω-3 supplementation on learning and major biological and behavioral stress markers. Male Sprague-Dawley rats were randomly assigned to three experimental groups: 1) Control, 2) Vehicle, animals supplemented with water, and 3) ω-3, rats supplemented with ω-3 (100 mg of DHA+25 mg of EPA). Each experimental group was divided into two subgroups: one of which was not subjected to stress while the other was subjected to a restraint stress paradigm. Afterwards, learning was analyzed by avoidance conditioning. As well, plasma corticosterone levels and anxiety were evaluated as stress markers, respectively by ELISA and the plus-maze test. Restraint stress impaired learning and increased both corticosterone levels and the number of entries into the open-arm (elevated plus-maze). These alterations were prevented by ω-3 supplementation. Thus, our results demonstrate that ω-3 supplementation had two beneficial effects on the stressed rats, a strong anti-stress effect and improved learning.
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Affiliation(s)
- Miguel Á Pérez
- Laboratory of Behavioral Neurobiology, Centro de Neurobiología y Plasticidad Cerebral, Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
- Graduate Program in Biology and Ecology Applied, Universidad Católica del Norte, Coquimbo, Chile
| | - Gonzalo Terreros
- Laboratory of Behavioral Neurobiology, Centro de Neurobiología y Plasticidad Cerebral, Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
| | - Alexies Dagnino-Subiabre
- Laboratory of Behavioral Neurobiology, Centro de Neurobiología y Plasticidad Cerebral, Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
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59
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Talip SB, Asari MA, Khan AA, Sirajudeen KNS. Evaluation of the protective effects of tocotrienol-rich fraction from palm oil on the dentate gyrus following chronic restraint stress in rats. BRAZ J PHARM SCI 2013. [DOI: 10.1590/s1984-82502013000200020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Exposure to chronic restraint stress has been shown to cause a number of morphological changes in the hippocampal formation of rats. Tocotrienol, an isoform of vitamin E, exhibits numerous health benefits, different from those of tocopherol. Recent studies have demonstrated that tocotrienol prevents stress-induced changes in the gastric mucosa, thus indicating that it may also protect other organs such as the brain from the damaging effects of stress. Therefore, the aim of the present study was to investigate the protective effect of tocotrienol-rich fraction (TRF) extracted from palm oil on the dentate gyrus of rats following exposure to chronic restraint stress. Thirty-six male Sprague Dawley rats were divided into four groups: control, stress, tocotrienol and combination of stress and tocotrienol. Animals were stressed by restraining them for 5 hours every day for 21 consecutive days. TRF was administered via oral gavage at a dose of 200 mg/kg body weight. Our results showed that the plasma corticosterone level was significantly increased in response to stress, compared to the control. The results confirmed previous findings that chronic restraint stress suppresses cellular proliferation and reduces granule cell number in the dentate gyrus. However, TRF supplementation failed to prevent or minimize these stress-induced changes. Therefore, we conclude that TRF at the current dosage is not effective in preventing the morphological changes in the dentate gyrus induced by chronic restraint stress.
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Repeated restraint stress impairs auditory attention and GABAergic synaptic efficacy in the rat auditory cortex. Neuroscience 2013; 246:94-107. [PMID: 23639878 DOI: 10.1016/j.neuroscience.2013.04.044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 04/01/2013] [Accepted: 04/21/2013] [Indexed: 11/22/2022]
Abstract
Chronic stress induces dendritic atrophy in the rat primary auditory cortex (A1), a key brain area for auditory attention. The aim of this study was to determine whether repeated restraint stress affects auditory attention and synaptic transmission in A1. Male Sprague-Dawley rats were trained in a two-alternative choice task (2-ACT), a behavioral paradigm to study auditory attention in rats. Trained animals that reached a performance over 80% of correct trials in the 2-ACT were randomly assigned to control and restraint stress experimental groups. To analyze the effects of restraint stress on the auditory attention, trained rats of both groups were subjected to 50 2-ACT trials one day before and one day after of the stress period. A difference score was determined by subtracting the number of correct trials after from those before the stress protocol. Another set of rats was used to study the synaptic transmission in A1. Restraint stress decreased the number of correct trials by 28% compared to the performance of control animals (p < 0.001). Furthermore, stress reduced the frequency of spontaneous inhibitory postsynaptic currents (sIPSC) and miniature IPSC in A1, whereas glutamatergic efficacy was not affected. Our results demonstrate that restraint stress decreased auditory attention and GABAergic synaptic efficacy in A1.
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61
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Cholesterol and perhaps estradiol protect against corticosterone-induced hippocampal CA3 dendritic retraction in gonadectomized female and male rats. Neuroscience 2013; 246:409-21. [PMID: 23618757 DOI: 10.1016/j.neuroscience.2013.04.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 11/23/2022]
Abstract
Chronic stress or glucocorticoid exposure simplifies hippocampal Cornu Ammonis region 3 (CA3) apical dendritic arbors in male rats. In contrast to males, chronic stress either reduces CA3 basal branching or exerts no observable morphological effects in gonadally intact female rats. Under conditions that females display stress-induced CA3 dendritic retraction, such as that following ovariectomy, chronic exposure to 17β-estradiol or cholesterol can negate these changes. Whether glucocorticoids produce CA3 dendritic retraction in ovariectomized females and whether neuroprotection from 17β-estradiol or cholesterol is sex-specific remains unknown. The current study examined the effects of chronic glucocorticoid exposure, in conjunction with 17β-estradiol or cholesterol administration, on hippocampal CA3 dendritic complexity. Adult male and female Sprague-Dawley rats were gonadectomized and implanted with 25% 17β-estradiol in cholesterol, 100% cholesterol, or blank Silastic capsules. Rats were then assigned to either a 21-day corticosterone (CORT) drink (400μg/ml CORT, 2.4% ethanol in tap water) or tap water (Tap, 2.4% ethanol in tap water) treatment. Brains were processed for Golgi staining, and hippocampal CA3 dendritic architecture was quantified. Results showed 21-day CORT administration reduced hippocampal CA3 apical dendritic branch points, CA3 apical dendritic length, body weight gain, and adrenal weights compared to male and female control counterparts. Furthermore, male and female rats implanted with Silastic capsules containing cholesterol or 25% 17β-estradiol in cholesterol were protected from CORT-induced CA3 apical dendritic branch reduction. No effects were observed in the CA3 basal dendritic arbors. The present results demonstrate that CORT produces hippocampal CA3 dendritic retraction in gonadectomized male and female rats and that cholesterol and 25% 17β-estradiol in cholesterol prevent this dendritic simplification.
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62
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Bisaz R, Boadas-Vaello P, Genoux D, Sandi C. Age-related cognitive impairments in mice with a conditional ablation of the neural cell adhesion molecule. Learn Mem 2013; 20:183-93. [PMID: 23504516 DOI: 10.1101/lm.030064.112] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Most of the mechanisms involved in neural plasticity support cognition, and aging has a considerable effect on some of these processes. The neural cell adhesion molecule (NCAM) of the immunoglobulin superfamily plays a pivotal role in structural and functional plasticity and is required to modulate cognitive and emotional behaviors. However, whether aging is associated with NCAM alterations that might contribute to age-related cognitive decline is not currently known. In this study, we determined whether conditional NCAM-deficient mice display increased vulnerability to age-related cognitive and emotional alterations. We assessed the NCAM expression levels in the hippocampus and medial prefrontal cortex (mPFC) and characterized the performance of adult and aged conditional NCAM-deficient mice and their age-matched wild-type littermates in a delayed matching-to-place test in the Morris water maze and a delayed reinforced alternation test in the T-maze. Although aging in wild-type mice is associated with an isoform-specific reduction of NCAM expression levels in the hippocampus and mPFC, these mice exhibited only mild impairments in working/episodic-like memory performance. However, aged conditional NCAM-deficient mice displayed pronounced impairments in both the delayed matching-to-place and the delayed reinforced alternation tests. Importantly, the deficits of aged NCAM-deficient mice in these working/episodic-like memory tasks could not be attributed to increased anxiety-like behaviors or to differences in locomotor activity. Taken together, these data indicate that reduced NCAM expression in the forebrain might be a critical factor for the occurrence of cognitive impairments during aging.
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Affiliation(s)
- Reto Bisaz
- Laboratory of Behavioral Genetics, Brain Mind Institute, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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63
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Schloesser RJ, Jimenez DV, Hardy NF, Paredes D, Catlow BJ, Manji HK, McKay RD, Martinowich K. Atrophy of pyramidal neurons and increased stress-induced glutamate levels in CA3 following chronic suppression of adult neurogenesis. Brain Struct Funct 2013; 219:1139-48. [PMID: 23483239 DOI: 10.1007/s00429-013-0532-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 02/21/2013] [Indexed: 01/12/2023]
Abstract
Following their birth in the adult hippocampal dentate gyrus, newborn progenitor cells migrate into the granule cell layer where they differentiate, mature, and functionally integrate into existing circuitry. The hypothesis that adult hippocampal neurogenesis is physiologically important has gained traction, but the precise role of newborn neurons in hippocampal function remains unclear. We investigated whether loss of new neurons impacts dendrite morphology and glutamate levels in area CA3 of the hippocampus by utilizing a human GFAP promoter-driven thymidine kinase genetic mouse model to conditionally suppress adult neurogenesis. We found that chronic ablation of new neurons induces remodeling in CA3 pyramidal cells and increases stress-induced release of the neurotransmitter glutamate. The ability of persistent impairment of adult neurogenesis to influence hippocampal dendrite morphology and excitatory amino acid neurotransmission has important implications for elucidating newborn neuron function, and in particular, understanding the role of these cells in stress-related excitoxicity.
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Affiliation(s)
- Robert J Schloesser
- Mood and Anxiety Disorders Program, National Institute of Mental Health (NIMH), National Institutes of Health (NIH), Bethesda, MD, 20892, USA
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Martínez-Claros M, Steinbusch H, van Selm A, van den Hove D, Prickaerts J, Pawluski J. Adrenalectomy and corticosterone replacement differentially alter CA3 dendritic morphology and new cell survival in the adult rat hippocampus. J Chem Neuroanat 2013; 48-49:23-8. [DOI: 10.1016/j.jchemneu.2013.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 01/08/2013] [Accepted: 01/08/2013] [Indexed: 12/28/2022]
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65
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Zhang E, Yau SY, Lau BWM, Ma H, Lee TMC, Chang RCC, So KF. Synaptic Plasticity, But not Hippocampal Neurogenesis, Mediated the Counteractive Effect of Wolfberry on Depression in Rats. Cell Transplant 2012; 21:2635-49. [DOI: 10.3727/096368912x655181] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Depression is a life-threatening psychiatric disorder characterized with a long-term hypercortisolemia in depressed patients. Based on this clinical feature, hypercortisolemia was mimicked in experimental animals to understand the neuropathogy of depression and to explore new therapeutic strategies. Wolfberry, also known as Lycium barbarum, is a type of common fruit produced in mainland China. Accumulated evidence has shown that the extracts from Lycium barbarum (LBP) had a wide range of neuroprotective effects in various neurogenerative models. However, the antidepressant effect of LBP on depression and its mechanism has not yet been explored. In the present study, we investigated the effects of LBP on counteracting depression using an animal model injected with moderate dose (40 mg/kg) or severe dose (50 mg/kg) of corticosterone (CORT) treatments for 14 days. The results showed that CORT significantly increased immobility time and decreased hippocampal cell proliferation. LBP treatment significantly decreased the immobility time in forced swimming test, a test for the intensity of depressive behaviors, both in 40 and 50 mg/kg CORT stressed rats. Moreover, LBP treatment restored the reduced proliferation of neuroprogentior cells in the hippocampus in 40 mg/kg CORT stressed rats and the neuronal differentiation but not the proliferation in 50 mg/kg CORT stressed rats. After ablation of adult neurogenesis with Ara-c infusion, the beneficial effect of LBP treatment in reducing immobility time was not affected in 40 and 50 mg/kg CORT stressed rats. Golgi staining and Western blotting detection showed that LBP treatment restored the reduced spine density and the decreased level of PSD-95 in the hippocampus caused by 40 and 50 mg/kg CORT, respectively, indicating enhanced synaptic plasticity in the hippocampus. The data showed a novel effect of LBP on reducing depression-like behavior and its antidepressant effect may be mediated by enhanced synaptic plasticity, but not hippocampal neurogenesis.
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Affiliation(s)
- Endong Zhang
- Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Suk Yu Yau
- Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Benson Wui Man Lau
- Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Henry Ma
- Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Tatia M. C. Lee
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
- Laboratory of Neuropsychology, The University of Hong Kong, Hong Kong, China
| | - Raymond Chuen-Chung Chang
- Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
- Research Centre of Heart, Brain, Hormone, and Healthy Aging, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Kwok Fai So
- Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
- Research Centre of Heart, Brain, Hormone, and Healthy Aging, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
- Joint Laboratory for Brain Function and Health (BFAH), Jinan University and The University of Hong Kong, Guangzhou, China
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The same antidepressant elicits contrasting patterns of synaptic changes in the amygdala vs hippocampus. Neuropsychopharmacology 2012; 37:2702-11. [PMID: 22828748 PMCID: PMC3473336 DOI: 10.1038/npp.2012.135] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
As depression-like symptoms are often precipitated by some form of stress, animal models of stress have been used extensively to investigate cellular mechanisms of depression. Despite being implicated in the emotional symptoms of depression, the amygdala has received little attention compared to the hippocampus in the past studies of antidepressant action. Further, these investigations have not taken into account the contrasting effects of chronic stress on the hippocampus vs amygdala. If an antidepressant is to be equally effective in countering the differential effects of stress on both brain areas, then it is faced with the challenge of eliciting contrasting effects in these two structures. We tested this prediction by examining the impact of tianeptine, an antidepressant with proven clinical efficacy, on neurons of the lateral amygdala (LA) and hippocampal area CA1. Tianeptine reduces N-methyl-D-aspartate (NMDA)-receptor-mediated synaptic currents, without affecting α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) currents, in LA neurons. By contrast, tianeptine enhances both NMDA and AMPA currents in area CA1. Tianeptine also lowers action potential firing in LA neurons. As tianeptine modulates cellular metrics that, in addition to mediating amygdalar behavioral output, are also affected by stress, we tested if tianeptine succeeds in countering stress effects in the intact animal. We find that tianeptine prevents two important functional consequences of chronic stress-induced plasticity in the amygdala--dendritic growth and enhanced anxiety-like behavior. These results provide evidence for antidepressant action on amygdalar neurons that are not only distinct from the hippocampus, but also protect against the debilitating impact of stress on amygdalar structure and function.
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Dagnino-Subiabre A, Pérez MÁ, Terreros G, Cheng MY, House P, Sapolsky R. Corticosterone treatment impairs auditory fear learning and the dendritic morphology of the rat inferior colliculus. Hear Res 2012; 294:104-13. [PMID: 23088831 DOI: 10.1016/j.heares.2012.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 09/27/2012] [Accepted: 09/30/2012] [Indexed: 12/18/2022]
Abstract
Stress leads to secretion of the adrenal steroid hormone corticosterone (CORT). The aim of this study was to determine the effects of chronic CORT administration on auditory and visual fear conditioning. Male Sprague-Dawley rats received CORT (400 mg/ml) in their drinking water for 10 consecutive days; this treatment induces stress levels of serum CORT. CORT impaired fear conditioning (F((1,28)) = 11.52, p < 0.01) and extinction (F((1,28)) = 4.86, p < 0.05) of auditory fear learning, but did not affect visual fear conditioning. In addition, we analyzed the CORT effects on the neuronal morphology of the inferior colliculus (flat neurons, auditory mesencephalon, a key brain area for auditory processing) and superior colliculus (wide-field neurons, related to visual processing) by Golgi stain. CORT decreased dendritic arborization of inferior colliculus neurons by approximately 50%, but did not affect superior colliculus neurons. Thus, CORT had more deleterious effects on the auditory fear processing than the visual system in the brain.
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Affiliation(s)
- Alexies Dagnino-Subiabre
- Laboratory of Behavioral Neurobiology, Center for Neurobiology and Brain Plasticity, Department of Physiology, Faculty of Sciences, Universidad de Valparaíso, Valparaíso, Chile.
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68
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Goodson M, Rust MB, Witke W, Bannerman D, Mott R, Ponting CP, Flint J. Cofilin-1: a modulator of anxiety in mice. PLoS Genet 2012; 8:e1002970. [PMID: 23055942 PMCID: PMC3464202 DOI: 10.1371/journal.pgen.1002970] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Accepted: 08/08/2012] [Indexed: 12/16/2022] Open
Abstract
The genes involved in conferring susceptibility to anxiety remain obscure. We developed a new method to identify genes at quantitative trait loci (QTLs) in a population of heterogeneous stock mice descended from known progenitor strains. QTLs were partitioned into intervals that can be summarized by a single phylogenetic tree among progenitors and intervals tested for consistency with alleles influencing anxiety at each QTL. By searching for common Gene Ontology functions in candidate genes positioned within those intervals, we identified actin depolymerizing factors (ADFs), including cofilin-1 (Cfl1), as genes involved in regulating anxiety in mice. There was no enrichment for function in the totality of genes under each QTL, indicating the importance of phylogenetic filtering. We confirmed experimentally that forebrain-specific inactivation of Cfl1 decreased anxiety in knockout mice. Our results indicate that similarity of function of mammalian genes can be used to recognize key genetic regulators of anxiety and potentially of other emotional behaviours.
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Affiliation(s)
- Martin Goodson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Marco B. Rust
- Neurobiology/Neurophysiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Walter Witke
- Institute of Genetics, University of Bonn, Bonn, Germany
| | - David Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Richard Mott
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Chris P. Ponting
- MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jonathan Flint
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
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Rao RP, Anilkumar S, McEwen BS, Chattarji S. Glucocorticoids protect against the delayed behavioral and cellular effects of acute stress on the amygdala. Biol Psychiatry 2012; 72:466-75. [PMID: 22572034 PMCID: PMC3753225 DOI: 10.1016/j.biopsych.2012.04.008] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 01/24/2023]
Abstract
BACKGROUND A single episode of acute immobilization stress has previously been shown to trigger a delayed onset of anxiety-like behavior and spinogenesis in the basolateral amygdala (BLA) of rats. Spurred on by a seemingly paradoxical observation in which even a modest increase in corticosterone (CORT), caused by a single vehicle injection before stress, could dampen the delayed effects of stress, we hypothesized a protective role for glucocorticoids against stress. METHODS We tested this hypothesis by analyzing how manipulations in CORT levels modulate delayed increase in anxiety-like behavior of rats on the elevated plus-maze 10 days after acute stress. We also investigated the cellular correlates of different levels of anxiety under different CORT conditions by quantifying spine density on Golgi-stained BLA principal neurons. RESULTS CORT in drinking water for 12 hours preceding acute stress prevented delayed increase in anxiety rather than exacerbating it. Conversely, vehicle injection failed to prevent the anxiogenic effect of stress in bilaterally adrenalectomized rats. However, when CORT was restored in adrenalectomized rats by injection, the delayed anxiogenic effect of stress was once again blocked. Finally, high and low anxiety states were accompanied by high and low levels of BLA spine density. CONCLUSIONS Our findings suggest that the presence of elevated levels of CORT at the time of acute stress confers protection against the delayed enhancing effect of stress on BLA synaptic connectivity and anxiety-like behavior. These observations are consistent with clinical reports on the protective effects of glucocorticoids against the development of posttraumatic symptoms triggered by traumatic stress.
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Affiliation(s)
- Rajnish P Rao
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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70
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McEwen BS. Structural plasticity of the adult brain: how animal models help us understand brain changes in depression and systemic disorders related to depression. DIALOGUES IN CLINICAL NEUROSCIENCE 2012. [PMID: 22034132 PMCID: PMC3181799 DOI: 10.31887/dcns.2004.6.2/bmcewen] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The brain interprets experiences and translates them into behavioral and physiological responses. Stressful events are those which are threatening or, at the very least, unexpected and surprising, and the physiological and behavioral responses are intended to promote adaptation via a process called “allostasis. ” Chemical mediators of allostasis include cortisol and adrenalin from the adrenal glands, other hormones, and neurotransmitters, the parasympathetic and sympathetic nervous systems, and cytokines and chemokines from the immune system. Two brain structures, the amygdala and hippocampus, play key roles in interpreting what is stressful and determining appropriate responses. The hippocampus, a key structure for memories of events and contexts, expresses receptors that enable it to respond to glucocorticoid hormones in the blood, it undergoes atrophy in a number of psychiatric disorders; it also responds to stressors with changes in excitability, decreased dendritic branching, and reduction in number of neurons in the dentate gyrus. The amygdala, which is important for “emotional memories, ” becomes hyperactive in posttraumatic stress disorder and depressive illness, in animal models of stress, there is evidence for growth and hypertrophy of nerve cells in the amygdala. Changes in the brain after acute and chronic stressors mirror the pattern seen in the metabolic, cardiovascular, and immune systems, that is, short-term adaptation (allostasis) followed by long-term damage (allostatic load), eg, atherosclerosis, fat deposition obesity, bone demineralization, and impaired immune function. Allostatic load of this kind is seen in major depressive illness and may also be expressed in other chronic anxiety and mood disorders.
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Affiliation(s)
- Bruce S McEwen
- Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY, USA
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71
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Mika A, Mazur GJ, Hoffman AN, Talboom JS, Bimonte-Nelson HA, Sanabria F, Conrad CD. Chronic stress impairs prefrontal cortex-dependent response inhibition and spatial working memory. Behav Neurosci 2012; 126:605-19. [PMID: 22905921 DOI: 10.1037/a0029642] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) that correspond to deficits in PFC-mediated behaviors. The present study examined the effects of chronic restraint stress on response inhibition (using a response-withholding task, the fixed-minimum interval schedule of reinforcement, or FMI), and working memory (using a radial arm water maze, RAWM). Adult male Sprague-Dawley rats were first trained on the RAWM and subsequently trained on FMI. After acquisition of FMI, rats were assigned to a restraint stress (6h/d/28d in wire mesh restrainers) or control condition. Immediately after chronic stress, rats were tested on FMI and subsequently on RAWM. FMI results suggest that chronic stress reduces response inhibition capacity and motivation to initiate the task on selective conditions when sucrose reward was not obtained on the preceding trial. RAWM results suggest that chronic stress produces transient deficits in working memory without altering previously consolidated reference memory. Behavioral measures from FMI failed to correlate with metrics from RAWM except for one in which changes in FMI timing imprecision negatively correlated with changes in RAWM working memory errors for the controls, a finding that was not observed following chronic stress. Fisher's r-to-z transformation revealed no significant differences between control and stress groups with correlation coefficients. These findings are the first to show that chronic stress impairs both response inhibition and working memory, two behaviors that have never been directly compared within the same animals after chronic stress, using FMI, an appetitive task, and RAWM, a nonappetitive task.
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Affiliation(s)
- Agnieszka Mika
- Department of Psychology, Arizona State University, Tempe, AZ85287-1104, USA
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72
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Fear conditioning can contribute to behavioral changes observed in a repeated stress model. Behav Brain Res 2012; 233:536-44. [DOI: 10.1016/j.bbr.2012.05.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/30/2012] [Accepted: 05/22/2012] [Indexed: 02/06/2023]
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Abstract
Previous studies in rodents showed that chronic stress induces structural and functional alterations in several brain regions, including shrinkage of the hippocampus and the prefrontal cortex, which are accompanied by cognitive and emotional disturbances. Reduced expression of the neural cell adhesion molecule (NCAM) following chronic stress has been proposed to be crucially involved in neuronal retraction and behavioral alterations. Since NCAM gene polymorphisms and altered expression of alternatively spliced NCAM isoforms have been associated with bipolar depression and schizophrenia in humans, we hypothesized that reduced expression of NCAM renders individuals more vulnerable to the deleterious effects of stress on behavior. Here, we specifically questioned whether mice in which the NCAM gene is inactivated in the forebrain by cre-recombinase under the control of the calcium-calmodulin-dependent kinase II promoter (conditional NCAM-deficient mice), display increased vulnerability to stress. We assessed the evolving of depressive-like behaviors and spatial learning and memory impairments following a subchronic stress protocol (2 weeks) that does not result in behavioral dysfunction, nor in altered NCAM expression, in wild-type mice. Indeed, while no behavioral alterations were detected in wild-type littermates after subchronic stress, conditional NCAM-deficient mice showed increased immobility in the tail suspension test and deficits in reversal spatial learning in the water maze. These findings indicate that diminished NCAM expression might be a critical vulnerability factor for the development of behavioral alterations by stress and further support a functional involvement of NCAM in stress-induced cognitive and emotional disturbances.
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Affiliation(s)
- Reto Bisaz
- Brain Mind Institute, Ecole Polytechnique Federale de LausanneCH-1015 Lausanne, Switzerland
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74
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Graybeal C, Kiselycznyk C, Holmes A. Stress-induced impairments in prefrontal-mediated behaviors and the role of the N-methyl-D-aspartate receptor. Neuroscience 2012; 211:28-38. [PMID: 22414923 DOI: 10.1016/j.neuroscience.2012.02.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/20/2012] [Accepted: 02/22/2012] [Indexed: 12/31/2022]
Abstract
The prefrontal cortex (PFC) mediates higher-order cognitive and executive functions that subserve various complex, adaptable behaviors, such as cognitive flexibility, attention, and working memory. Deficits in these functions typify multiple neuropsychiatric disorders that are caused or exacerbated by exposure to psychological stress. Here we review recent evidence examining the effects of stress on executive and cognitive functions in rodents and discuss an emerging body of evidence that implicates the N-methyl-D-aspartate receptor (NMDAR) as a potentially critical molecular mechanism mediating these effects. Future work in this area could open up new avenues for developing pharmacotherapies for ameliorating cognitive dysfunction in neuropsychiatric disease.
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Affiliation(s)
- C Graybeal
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892-9304, USA.
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Hutchinson KM, McLaughlin KJ, Wright RL, Bryce Ortiz J, Anouti DP, Mika A, Diamond DM, Conrad CD. Environmental enrichment protects against the effects of chronic stress on cognitive and morphological measures of hippocampal integrity. Neurobiol Learn Mem 2012; 97:250-60. [PMID: 22266288 DOI: 10.1016/j.nlm.2012.01.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 12/31/2011] [Accepted: 01/05/2012] [Indexed: 12/12/2022]
Abstract
Chronic stress has detrimental effects on hippocampal integrity, while environmental enrichment (EE) has beneficial effects when initiated early in development. In this study, we investigated whether EE initiated in adulthood would mitigate chronic stress effects on cognitive function and hippocampal neuronal architecture, when EE started one week before chronic stress began, or two weeks after chronic stress onset. Adult male Sprague Dawley rats were chronically restrained (6h/d) or assigned as non-stressed controls and subdivided into EE or non-EE housing. After restraint ended, rats were tested on a radial arm water maze (RAWM) for 2-d to assess spatial learning and memory. The first study showed that when EE began prior to 3-weeks of chronic stress, EE attenuated chronic stress-induced impairments in acquisition, which corresponded with the prevention of chronic stress-induced reductions in CA3 apical dendritic length. A second study showed that when EE began 2-weeks after the onset of a 5-week stress regimen, EE blocked chronic stress-induced impairments in acquisition and retention at 1-h and 24-h delays. RAWM performance corresponded with CA3 apical dendritic complexity. Moreover, rats in EE housing (control or stress) exhibited similar corticosterone profiles across weeks, which differed from the muted corticosterone response to restraint by the chronically stressed pair-housed rats. These data support the interpretation that chronic stress and EE may act on similar mechanisms within the hippocampus, and that manipulation of these factors may yield new directions for optimizing brain integrity and resilience under chronic stress or stress related neuropsychological disorders in the adult.
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Affiliation(s)
- Katie M Hutchinson
- Department of Psychology, Arizona State University, Tempe, AZ 85287-1104, USA
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76
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Oztan O, Aydin C, Isgor C. Chronic variable physical stress during the peripubertal-juvenile period causes differential depressive and anxiogenic effects in the novelty-seeking phenotype: functional implications for hippocampal and amygdalar brain-derived neurotrophic factor and the mossy fibre plasticity. Neuroscience 2011; 192:334-44. [PMID: 21767611 PMCID: PMC3166372 DOI: 10.1016/j.neuroscience.2011.06.077] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 06/26/2011] [Accepted: 06/28/2011] [Indexed: 11/16/2022]
Abstract
Experimentally naive rats show variance in their locomotor reactivity to novelty, some displaying higher (HR) while others displaying lower (LR) reactivity, associated with vulnerability to stress. We employed a chronic variable physical stress regimen incorporating intermittent and random exposures of physical stressors or control handling during the peripubertal-juvenile period to assess interactions between stress and the LRHR phenotype in depressive- and anxiety-like behaviors on the forced swim and social interaction tests, respectively. A decrease in immobility in the forced swim test along with a decrease in social contact in the social interaction test were observed in the juvenile HRs, coupled with increases in brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus and in the basolateral amygdala with chronic variable physical stress. In contrast, an increase in immobility in the forced swim test and a decrease in social contact was observed in the LR counterparts coupled with an increase in the BDNF mRNA in the basolateral amygdala following chronic variable physical stress. Furthermore, chronic physical stress led to increased H3 and H4 acetylation at the P2 and P4 promoters of the hippocampal BDNF gene in the HR rats that is associated with increased suprapyramidal mossy fibre (SP-MF) terminal field volume. In contrast, chronic variable physical stress led to decreased H4 acetylation at the P4 promoter, associated with decreased SP-MF volume in the LR rats. These findings show dissociation in depressive- and anxiety-like behaviors following chronic variable physical stress in the juvenile HR animals that may be mediated by increased levels of BDNF in the hippocampus and in the amygdala, respectively. Moreover, chronic variable physical stress during the peripubertal-juvenile period results in opposite effects in depressive-like behavior in the LRHR rats by way of inducing differential epigenetic regulation of the hippocampal BDNF gene that, in turn, may mediate mossy fibre sprouting.
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Affiliation(s)
- O Oztan
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Department of Biomedical Science, Boca Raton, FL 33431, USA
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Waters P, McCormick CM. Caveats of chronic exogenous corticosterone treatments in adolescent rats and effects on anxiety-like and depressive behavior and hypothalamic-pituitary-adrenal (HPA) axis function. BIOLOGY OF MOOD & ANXIETY DISORDERS 2011; 1:4. [PMID: 22738136 PMCID: PMC3377168 DOI: 10.1186/2045-5380-1-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 09/27/2011] [Indexed: 12/27/2022]
Abstract
BACKGROUND Administration of exogenous corticosterone is an effective preclinical model of depression, but its use has involved primarily adult rodents. Using two different procedures of administration drawn from the literature, we explored the possibility of exogenous corticosterone models in adolescence, a time of heightened risk for mood disorders in humans. METHODS In experiment 1, rats were injected with 40 mg/kg corticosterone or vehicle from postnatal days 30 to 45 and compared with no injection controls on behavior in the elevated plus maze (EPM) and the forced swim test (FST). Experiment 2 consisted of three treatments administered to rats from postnatal days 30 to 45 or as adults (days 70 to 85): either corticosterone (400 μg/ml) administered in the drinking water along with 2.5% ethanol, 2.5% ethanol or water only. In addition to testing on EPM, blood samples after the FST were obtained to measure plasma corticosterone. Analysis of variance (ANOVA) and alpha level of P < 0.05 were used to determine statistical significance. RESULTS In experiment 1, corticosterone treatment of adolescent rats increased anxiety in the EPM and decreased immobility in the FST compared to no injection control rats. However, vehicle injected rats were similar to corticosterone injected rats, suggesting that adolescent rats may be highly vulnerable to stress of injection. In experiment 2, the intake of treated water, and thus doses delivered, differed for adolescents and adults, but there were no effects of treatment on behavior in the EPM or FST. Rats that had ingested corticosterone had reduced corticosterone release after the FST. Ethanol vehicle also affected corticosterone release compared to those ingesting water only, but differently for adolescents than for adults. CONCLUSIONS The results indicate that several challenges must be overcome before the exogenous corticosterone model can be used effectively in adolescents.
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Affiliation(s)
- Patti Waters
- Department of Psychology and Centre for Neuroscience, Brock University, St Catharines, Ontario, Canada
| | - Cheryl M McCormick
- Department of Psychology and Centre for Neuroscience, Brock University, St Catharines, Ontario, Canada
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Veena J, Srikumar BN, Mahati K, Raju TR, Shankaranarayana Rao BS. Oxotremorine treatment restores hippocampal neurogenesis and ameliorates depression-like behaviour in chronically stressed rats. Psychopharmacology (Berl) 2011; 217:239-53. [PMID: 21494789 DOI: 10.1007/s00213-011-2279-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 03/22/2011] [Indexed: 12/21/2022]
Abstract
RATIONALE Chronic stress results in cognitive impairment, affects hippocampal neurogenesis and is known to precipitate affective disorders such as depression. In addition to stress, neurotransmitters such as acetylcholine (ACh) modulate adult neurogenesis. Earlier, we have shown that oxotremorine, a cholinergic muscarinic agonist, ameliorates stress-induced cognitive impairment and restores cholinergic function. OBJECTIVES In the current study, we have looked into the possible involvement of adult neurogenesis in cognitive restoration by oxotremorine. Further, we have assessed the effect of oxotremorine treatment on depression-like behaviour and hippocampal volumes in stressed animals. METHODS Chronic restraint stressed rats were treated with either vehicle or oxotremorine. For neurogenesis studies, proliferation, survival and differentiation of the progenitor cells in the hippocampus were examined using 5'-bromo-2-deoxyuridine immunohistochemistry. Depression-like behaviour was evaluated using forced swim test (FST) and sucrose consumption test (SCT). Volumes were estimated using Cavalieri's estimator. RESULTS Hippocampal neurogenesis was severely decreased in stressed rats. Ten days of oxotremorine treatment to stressed animals partially restored proliferation and survival, while it completely restored the differentiation of the newly formed cells. Stressed rats showed increased immobility and decreased sucrose preference in the FST and SCT, respectively, and oxotremorine ameliorated this depression-like behaviour. In addition, oxotremorine treatment recovered the stress-induced decrease in hippocampal volume. CONCLUSIONS These results indicate that the restoration of impaired neurogenesis and hippocampal volume could be associated with the behavioural recovery by oxotremorine. Our results imply the muscarinic regulation of adult neurogenesis and incite the potential utility of cholinomimetics in ameliorating cognitive dysfunction in stress-related disorders.
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Affiliation(s)
- J Veena
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Hosur Road, PB # 2900, Bangalore, 560 029, India
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79
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Dagytė G, Den Boer JA, Trentani A. The cholinergic system and depression. Behav Brain Res 2011; 221:574-82. [PMID: 20170685 DOI: 10.1016/j.bbr.2010.02.023] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 02/10/2010] [Indexed: 01/07/2023]
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80
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Bowirrat A, Chen TJH, Blum K, Madigan M, Bailey JA, Chuan Chen AL, Downs BW, Braverman ER, Radi S, Waite RL, Kerner M, Giordano J, Morse S, Oscar-Berman M, Gold M. Neuro-psychopharmacogenetics and Neurological Antecedents of Posttraumatic Stress Disorder: Unlocking the Mysteries of Resilience and Vulnerability. Curr Neuropharmacol 2011; 8:335-58. [PMID: 21629442 PMCID: PMC3080591 DOI: 10.2174/157015910793358123] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 02/17/2010] [Accepted: 02/22/2010] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND HYPOTHESIS Although the biological underpinnings of immediate and protracted trauma-related responses are extremely complex, 40 years of research on humans and other mammals have demonstrated that trauma (particularly trauma early in the life cycle) has long-term effects on neurochemical responses to stressful events. These effects include the magnitude of the catecholamine response and the duration and extent of the cortisol response. In addition, a number of other biological systems are involved, including mesolimbic brain structures and various neurotransmitters. An understanding of the many genetic and environmental interactions contributing to stress-related responses will provide a diagnostic and treatment map, which will illuminate the vulnerability and resilience of individuals to Posttraumatic Stress Disorder (PTSD). PROPOSAL AND CONCLUSIONS We propose that successful treatment of PTSD will involve preliminary genetic testing for specific polymorphisms. Early detection is especially important, because early treatment can improve outcome. When genetic testing reveals deficiencies, vulnerable individuals can be recommended for treatment with "body friendly" pharmacologic substances and/or nutrients. Results of our research suggest the following genes should be tested: serotoninergic, dopaminergic (DRD2, DAT, DBH), glucocorticoid, GABAergic (GABRB), apolipoprotein systems (APOE2), brain-derived neurotrophic factor, Monamine B, CNR1, Myo6, CRF-1 and CRF-2 receptors, and neuropeptide Y (NPY). Treatment in part should be developed that would up-regulate the expression of these genes to bring about a feeling of well being as well as a reduction in the frequency and intensity of the symptoms of PTSD.
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Affiliation(s)
- Abdalla Bowirrat
- Clinical Neuroscience & Population Genetics, and Department of Neurology, Ziv Medical Center, Safed, Israel
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Vestergaard-Poulsen P, Wegener G, Hansen B, Bjarkam CR, Blackband SJ, Nielsen NC, Jespersen SN. Diffusion-weighted MRI and quantitative biophysical modeling of hippocampal neurite loss in chronic stress. PLoS One 2011; 6:e20653. [PMID: 21747929 PMCID: PMC3128590 DOI: 10.1371/journal.pone.0020653] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 05/06/2011] [Indexed: 01/21/2023] Open
Abstract
Chronic stress has detrimental effects on physiology, learning and memory and is involved in the development of anxiety and depressive disorders. Besides changes in synaptic formation and neurogenesis, chronic stress also induces dendritic remodeling in the hippocampus, amygdala and the prefrontal cortex. Investigations of dendritic remodeling during development and treatment of stress are currently limited by the invasive nature of histological and stereological methods. Here we show that high field diffusion-weighted MRI combined with quantitative biophysical modeling of the hippocampal dendritic loss in 21 day restraint stressed rats highly correlates with former histological findings. Our study strongly indicates that diffusion-weighted MRI is sensitive to regional dendritic loss and thus a promising candidate for non-invasive studies of dendritic plasticity in chronic stress and stress-related disorders.
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82
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Matrisciano F, Busceti CL, Bucci D, Orlando R, Caruso A, Molinaro G, Cappuccio I, Riozzi B, Gradini R, Motolese M, Caraci F, Copani A, Scaccianoce S, Melchiorri D, Bruno V, Battaglia G, Nicoletti F. Induction of the Wnt antagonist Dickkopf-1 is involved in stress-induced hippocampal damage. PLoS One 2011; 6:e16447. [PMID: 21304589 PMCID: PMC3029367 DOI: 10.1371/journal.pone.0016447] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Accepted: 12/29/2010] [Indexed: 11/19/2022] Open
Abstract
The identification of mechanisms that mediate stress-induced hippocampal damage may shed new light into the pathophysiology of depressive disorders and provide new targets for therapeutic intervention. We focused on the secreted glycoprotein Dickkopf-1 (Dkk-1), an inhibitor of the canonical Wnt pathway, involved in neurodegeneration. Mice exposed to mild restraint stress showed increased hippocampal levels of Dkk-1 and reduced expression of β-catenin, an intracellular protein positively regulated by the canonical Wnt signalling pathway. In adrenalectomized mice, Dkk-1 was induced by corticosterone injection, but not by exposure to stress. Corticosterone also induced Dkk-1 in mouse organotypic hippocampal cultures and primary cultures of hippocampal neurons and, at least in the latter model, the action of corticosterone was reversed by the type-2 glucocorticoid receptor antagonist mifepristone. To examine whether induction of Dkk-1 was causally related to stress-induced hippocampal damage, we used doubleridge mice, which are characterized by a defective induction of Dkk-1. As compared to control mice, doubleridge mice showed a paradoxical increase in basal hippocampal Dkk-1 levels, but no Dkk-1 induction in response to stress. In contrast, stress reduced Dkk-1 levels in doubleridge mice. In control mice, chronic stress induced a reduction in hippocampal volume associated with neuronal loss and dendritic atrophy in the CA1 region, and a reduced neurogenesis in the dentate gyrus. Doubleridge mice were resistant to the detrimental effect of chronic stress and, instead, responded to stress with increases in dendritic arborisation and neurogenesis. Thus, the outcome of chronic stress was tightly related to changes in Dkk-1 expression in the hippocampus. These data indicate that induction of Dkk-1 is causally related to stress-induced hippocampal damage and provide the first evidence that Dkk-1 expression is regulated by corticosteroids in the central nervous system. Drugs that rescue the canonical Wnt pathway may attenuate hippocampal damage in major depression and other stress-related disorders.
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Affiliation(s)
| | | | - Domenico Bucci
- Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | - Rosamaria Orlando
- Department of Physiology and Pharmacology, University “Sapienza”, Roma, Italy
| | - Alessandra Caruso
- Department of Physiology and Pharmacology, University “Sapienza”, Roma, Italy
| | - Gemma Molinaro
- Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | | | - Barbara Riozzi
- Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | - Roberto Gradini
- Department of Experimental Medicine, University “Sapienza”, Roma, Italy
| | - Marta Motolese
- Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | - Filippo Caraci
- Department of Pharmaceutical Sciences, University of Catania, Catania, Italy
| | - Agata Copani
- Department of Pharmaceutical Sciences, University of Catania, Catania, Italy
| | - Sergio Scaccianoce
- Department of Physiology and Pharmacology, University “Sapienza”, Roma, Italy
| | - Daniela Melchiorri
- Department of Physiology and Pharmacology, University “Sapienza”, Roma, Italy
- Istituto San Raffaele Pisana, Roma, Italy
| | - Valeria Bruno
- Department of Physiology and Pharmacology, University “Sapienza”, Roma, Italy
- Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | | | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, University “Sapienza”, Roma, Italy
- Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
- * E-mail:
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83
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Crupi R, Mazzon E, Marino A, La Spada G, Bramanti P, Battaglia F, Cuzzocrea S, Spina E. Hypericum perforatum treatment: effect on behaviour and neurogenesis in a chronic stress model in mice. Altern Ther Health Med 2011; 11:7. [PMID: 21272291 PMCID: PMC3041724 DOI: 10.1186/1472-6882-11-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 01/27/2011] [Indexed: 01/19/2023]
Abstract
Background Extracts of Hypericum perforatum (St. John's wort) have been traditionally recommended for a wide range of medical conditions, in particular mild-to-moderate depression. The present study was designed to investigate the effect of Hypericum perforatum treatment in a mouse model of anxiety/depressive-like behavior, induced by chronic corticosterone administration. Methods CD1 mice were submitted to 7 weeks corticosterone administration and then behavioral tests as Open Field (OF), Novelty-Suppressed Feeding (NSF), Forced Swim Test (FST) were performed. Cell proliferation in hippocampal dentate gyrus (DG) was investigated by both 5-bromo-2'-deoxyuridine (BrdU) and doublecortin (DCX) immunohistochemistry techniques and stereological procedure was used to quantify labeled cells. Golgi-impregnation method was used to evaluate changes in dendritic spines in DG. Hypericum perforatum (30 mg/Kg) has been administered for 3 weeks and then neural development in the adult hippocampus and behavioral changes have been examined. Results The anxiety/depressive-like state due to chronic corticosterone treatment was reversed by exogenous administration of Hypericum perforatum; the proliferation of progenitor cells in mice hippocampus was significantly reduced under chronic corticosterone treatment, whereas a long term treatment with Hypericum perforatum prevented the corticosterone-induced decrease in hippocampal cell proliferation. Corticosterone-treated mice exhibited a reduced spine density that was ameliorated by Hypericum perforatum administration. Conclusion These results provide evidence of morphological adaptations occurring in mature hippocampal neurons that might underlie resilient responses to chronic stress and contribute to the therapeutic effects of chronic Hypericum perforatum treatment.
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84
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Wager-Smith K, Markou A. Depression: a repair response to stress-induced neuronal microdamage that can grade into a chronic neuroinflammatory condition? Neurosci Biobehav Rev 2011; 35:742-64. [PMID: 20883718 PMCID: PMC3777427 DOI: 10.1016/j.neubiorev.2010.09.010] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 09/17/2010] [Accepted: 09/21/2010] [Indexed: 12/19/2022]
Abstract
Depression is a major contributor to the global burden of disease and disability, yet it is poorly understood. Here we review data supporting a novel theoretical model for the biology of depression. In this model, a stressful life event leads to microdamage in the brain. This damage triggers an injury repair response consisting of a neuroinflammatory phase to clear cellular debris and a spontaneous tissue regeneration phase involving neurotrophins and neurogenesis. During healing, released inflammatory mediators trigger sickness behavior and psychological pain via mechanisms similar to those that produce physical pain during wound healing. The depression remits if the neuronal injury repair process resolves successfully. Importantly, however, the acute psychological pain and neuroinflammation often transition to chronicity and develop into pathological depressive states. This hypothesis for depression explains substantially more data than alternative models, including why emerging data show that analgesic, anti-inflammatory, pro-neurogenic and pro-neurotrophic treatments have antidepressant effects. Thus, an acute depressive episode can be conceptualized as a normally self-limiting but highly error-prone process of recuperation from stress-triggered neuronal microdamage.
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Affiliation(s)
- Karen Wager-Smith
- Department of Psychiatry, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0603, USA.
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85
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de Souza-Talarico JN, Marin MF, Sindi S, Lupien SJ. Effects of stress hormones on the brain and cognition: Evidence from normal to pathological aging. Dement Neuropsychol 2011; 5:8-16. [PMID: 29213714 PMCID: PMC5619133 DOI: 10.1590/s1980-57642011dn05010003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 02/14/2011] [Indexed: 12/04/2022] Open
Abstract
Several studies have demonstrated a wide cognitive variability among aged individuals. One factor thought to be associated with this heterogeneity is exposure to chronic stress throughout life. Animal and human evidence demonstrates that glucocorticoids (GCs), the main class of stress hormones, are strongly linked to memory performance whereby elevated GC levels are associated with memory performance decline in both normal and pathological cognitive aging. Accordingly, it is believed that GCs may increase the brain's vulnerability to the effects of internal and external insults, and thus may play a role in the development of age-related cognitive disorders such as Alzheimer's disease (AD). The aim of this review article was to investigate the effects of GCs on normal and pathological cognitive aging by showing how these hormones interact with different brain structures involved in cognitive abilities, subsequently worsen memory performance, and increase the risk for developing dementia.
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Affiliation(s)
- Juliana Nery de Souza-Talarico
- PhD, Department of Medical-Surgical Nursing, School of
Nursing, University of São Paulo, São Paulo SP, Brazil and Behavioral
and Cognitive Neurology Unit, Department of Neurology, Faculty of Medicine,
University of São Paulo, São Paulo SP, Brazil
| | - Marie-France Marin
- MSc, Center for Studies on Human Stress, Mental Health
Research Center Fernand-Seguin, Louis-H. Lafontaine Hospital, Université de
Montreal, Canada
| | - Shireen Sindi
- MSc, Department of Neurology and Neurosurgery, McGill
University, Montreal, Canada
| | - Sonia J. Lupien
- PhD, Center for Studies on Human Stress, Mental Health
Research Center Fernand-Seguin, Louis-H. Lafontaine Hospital, Université de
Montreal, Canada
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86
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Christian KM, Miracle AD, Wellman CL, Nakazawa K. Chronic stress-induced hippocampal dendritic retraction requires CA3 NMDA receptors. Neuroscience 2010; 174:26-36. [PMID: 21108993 DOI: 10.1016/j.neuroscience.2010.11.033] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 11/12/2010] [Accepted: 11/15/2010] [Indexed: 01/06/2023]
Abstract
Chronic stress induces dendritic retraction in the hippocampal CA3 subregion, but the mechanisms responsible for this retraction and its impact on neural circuitry are not well understood. To determine the role of NMDA (N-methyl-d-aspartic acid) receptor (NMDAR)-mediated signaling in this process, we compared the effects of chronic immobilization stress (CIS) on hippocampal dendritic morphology, hypothalamic-pituitary-adrenal (HPA) axis activation, and anxiety-related and hippocampus-dependent behaviors, in transgenic male mice in which the NMDAR had been selectively deleted in CA3 pyramidal cells and in non-mutant littermates. We found that CIS exposure for 10 consecutive days in non-mutant mice effectively induces HPA axis activation and dendritic retraction of CA3 short-shaft pyramidal neurons, but not CA3 long-shaft pyramidal neurons, suggesting a differential cellular stress response in this region. Dendritic reorganization of short-shaft neurons occurred throughout the longitudinal axis of the hippocampus and, in particular, in the ventral pole of this structure. We also observed a robust retraction of dendrites in dorsal CA1 pyramidal neurons in the non-mutant C57BL/6 mouse strain. Strikingly, chronic stress-induced dendritic retraction was not evident in any of the neurons in either CA3 or CA1 in the mutant mice that had a functional lack of NMDARs restricted to CA3 pyramidal neurons. Interestingly, the prevention of dendritic retraction in the mutant mice had a minimal effect on HPA axis activation and behavioral alterations that were induced by chronic stress. These data support a role for NMDAR-dependent glutamatergic signaling in CA3 in the cell-type specific induction of dendritic retraction in two hippocampal subregions following chronic stress.
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Affiliation(s)
- K M Christian
- Unit on Genetics of Cognition and Behavior, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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87
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Beneficial Effects of Tianeptine on Hippocampus-Dependent Long-Term Memory and Stress-Induced Alterations of Brain Structure and Function. Pharmaceuticals (Basel) 2010. [PMCID: PMC4034085 DOI: 10.3390/ph3103143] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Tianeptine is a well-described antidepressant which has been shown to prevent stress from producing deleterious effects on brain structure and function. Preclinical studies have shown that tianeptine blocks stress-induced alterations of neuronal morphology and synaptic plasticity. Moreover, tianeptine prevents stress from impairing learning and memory, and, importantly, demonstrates memory-enhancing properties in the absence of stress. Recent research has indicated that tianeptine works by normalizing glutamatergic neurotransmission, a mechanism of action that may underlie its effectiveness as an antidepressant. These findings emphasize the value in focusing on the mechanisms of action of tianeptine, and specifically, the glutamatergic system, in the development of novel pharmacotherapeutic strategies in the treatment of depression.
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88
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Bisphenol A interferes with synaptic remodeling. Front Neuroendocrinol 2010; 31:519-30. [PMID: 20609373 PMCID: PMC2964437 DOI: 10.1016/j.yfrne.2010.06.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 06/11/2010] [Accepted: 06/25/2010] [Indexed: 11/21/2022]
Abstract
The potential adverse effects of Bisphenol A (BPA), a synthetic xenoestrogen, have long been debated. Although standard toxicology tests have revealed no harmful effects, recent research highlighted what was missed so far: BPA-induced alterations in the nervous system. Since 2004, our laboratory has been investigating one of the central effects of BPA, which is interference with gonadal steroid-induced synaptogenesis and the resulting loss of spine synapses. We have shown in both rats and nonhuman primates that BPA completely negates the ∼ 70-100% increase in the number of hippocampal and prefrontal spine synapses induced by both estrogens and androgens. Synaptic loss of this magnitude may have significant consequences, potentially causing cognitive decline, depression, and schizophrenia, to mention those that our laboratory has shown to be associated with synaptic loss. Finally, we discuss why children may particularly be vulnerable to BPA, which represents future direction of research in our laboratory.
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89
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Iyo AH, Feyissa AM, Chandran A, Austin MC, Regunathan S, Karolewicz B. Chronic corticosterone administration down-regulates metabotropic glutamate receptor 5 protein expression in the rat hippocampus. Neuroscience 2010; 169:1567-74. [PMID: 20600666 PMCID: PMC2918667 DOI: 10.1016/j.neuroscience.2010.06.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/09/2010] [Accepted: 06/10/2010] [Indexed: 11/23/2022]
Abstract
Several lines of evidence suggest a dysfunctional glutamate system in major depressive disorder (MDD). Recently, we reported reduced levels of metabotropic glutamate receptor subtype 5 (mGluR5) in postmortem brains in MDD, however the neurobiological mechanisms that induce these abnormalities are unclear. In the present study, we examined the effect of chronic corticosterone (CORT) administration on the expression of mGluR5 protein and mRNA in the rat frontal cortex and hippocampus. Rats were injected with CORT (40 mg/kg s.c.) or vehicled once daily for 21 days. The expression of mGluR5 protein and mRNA was assessed by Western blotting and quantitative real-time PCR (qPCR). In addition, mGluR1 protein was measured in the same animals. The results revealed that while there was a significant reduction (-27%, P=0.0006) in mGluR5 protein expression in the hippocampus from CORT treated rats, mRNA levels were unchanged. Also unchanged were mGluR5 mRNA and protein levels in the frontal cortex and mGluR1 protein levels in both brain regions. Our findings provide the first evidence that chronic CORT exposure regulates the expression of mGluR5 and are in line with previous postmortem and imaging studies showing reduced mGluR5 in MDD. Our findings suggest that elevated levels of glucocorticoids may contribute to impairments in glutamate neurotransmission in MDD.
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Affiliation(s)
- A H Iyo
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA
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90
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Alkadhi KA, Srivareerat M, Tran TT. Intensification of long-term memory deficit by chronic stress and prevention by nicotine in a rat model of Alzheimer's disease. Mol Cell Neurosci 2010; 45:289-96. [PMID: 20624465 DOI: 10.1016/j.mcn.2010.06.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2010] [Revised: 06/24/2010] [Accepted: 06/28/2010] [Indexed: 12/28/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cholinergic dysfunction and deposition of beta-amyloid (Aβ) in regions of the brain associated with learning and memory. The sporadic nature and late onset of most AD cases suggests that aside from biological determinants, environmental factors such as stress may also play a role in the progression of the disease. Behavioral and molecular studies were utilized to evaluate the effects of chronic nicotine treatment in the prevention of impairment of long-term memory. The rat model of AD was induced by i.c.v. osmotic pump infusion of Aβ peptides. Chronic psychosocial stress and chronic nicotine treatment were instituted for 6weeks. Spatial memory testing in the Radial Arm Water Maze revealed that, although stress, by itself, did not affect long-term memory, the combination of chronic stress and Aβ infusion impaired long-term memory significantly more than Aβ peptides infusion alone. Chronic nicotine treatment completely prevented Aβ- and stress/Aβ combination-induced memory impairment. Furthermore, molecular findings in hippocampal CA1 region of stress/Aβ rats indicated marked reduction in the protein levels of phosphorylated cAMP response element binding (p-CREB) and calcium-calmodulin-dependent protein kinase IV (CaMKIV), with significant increases in the levels of brain-derived neurotrophic factor (BDNF). These disturbances in signaling pathways, which may be the underlying mechanisms of impairment of long-term memory in these rats, were totally prevented by chronic nicotine treatment.
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Affiliation(s)
- Karim A Alkadhi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204-5037, USA.
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91
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Krugers HJ, Lucassen PJ, Karst H, Joëls M. Chronic stress effects on hippocampal structure and synaptic function: relevance for depression and normalization by anti-glucocorticoid treatment. Front Synaptic Neurosci 2010; 2:24. [PMID: 21423510 PMCID: PMC3059694 DOI: 10.3389/fnsyn.2010.00024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 06/07/2010] [Indexed: 01/08/2023] Open
Abstract
Exposure of an organism to environmental challenges activates two hormonal systems that help the organism to adapt. As part of this adaptational process, brain processes are changed such that appropriate behavioral strategies are selected that allow optimal performance at the short term, while relevant information is stored for the future. Over the past years it has become evident that chronic uncontrollable and unpredictable stress also exerts profound effects on structure and function of limbic neurons, but the impact of chronic stress is not a mere accumulation of repeated episodes of acute stress exposure. Dendritic trees are reduced in some regions but expanded in others, and cells are generally exposed to a higher calcium load upon depolarization. Synaptic strengthening is largely impaired. Neurotransmitter responses are also changed, e.g., responses to serotonin. We here discuss: (a) the main cellular effects after chronic stress with emphasis on the hippocampus, (b) how such effects could contribute to the development of psychopathology in genetically vulnerable individuals, and (c) their normalization by brief treatment with anti-glucocorticoids.
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Affiliation(s)
- Harmen J. Krugers
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
| | - Paul J. Lucassen
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
| | - Henk Karst
- Department of Neuroscience and Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Center UtrechtUtrecht, Netherlands
| | - Marian Joëls
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
- Department of Neuroscience and Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Center UtrechtUtrecht, Netherlands
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92
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A critical review of chronic stress effects on spatial learning and memory. Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:742-55. [PMID: 19903505 DOI: 10.1016/j.pnpbp.2009.11.003] [Citation(s) in RCA: 231] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 10/23/2009] [Accepted: 11/03/2009] [Indexed: 01/23/2023]
Abstract
The purpose of this review is to evaluate the effects of chronic stress on hippocampal-dependent function, based primarily upon studies using young, adult male rodents and spatial navigation tasks. Despite this restriction, variability amongst the findings was evident and how or even whether chronic stress influenced spatial ability depended upon the type of task, the dependent variable measured and how the task was implemented, the type and duration of the stressors, housing conditions of the animals that include accessibility to food and cage mates, and duration from the end of the stress to the start of behavioral assessment. Nonetheless, patterns emerged as follows: For spatial memory, chronic stress impairs spatial reference memory and has transient effects on spatial working memory. For spatial learning, however, chronic stress effects appear to be task-specific: chronic stress impairs spatial learning on appetitively motivated tasks, such as the radial arm maze or holeboard, tasks that evoke relatively mild to low arousal components from fear. But under testing conditions that evoke moderate to strong arousal components from fear, such as during radial arm water maze testing, chronic stress appears to have minimal impairing effects or may even facilitate spatial learning. Chronic stress clearly impacts nearly every brain region and thus, how chronic stress alters hippocampal spatial ability likely depends upon the engagement of other brain structures during behavioral training and testing.
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93
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Zoladz PR, Park CR, Muñoz C, Fleshner M, Diamond DM. Tianeptine: an antidepressant with memory-protective properties. Curr Neuropharmacol 2010; 6:311-21. [PMID: 19587852 PMCID: PMC2701287 DOI: 10.2174/157015908787386096] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 08/15/2008] [Accepted: 08/25/2008] [Indexed: 01/17/2023] Open
Abstract
The development of effective pharmacotherapy for major depression is important because it is such a widespread and debilitating mental disorder. Here, we have reviewed preclinical and clinical studies on tianeptine, an atypical antidepressant which ameliorates the adverse effects of stress on brain and memory. In animal studies, tianeptine has been shown to prevent stress-induced morphological sequelae in the hippocampus and amygdala, as well as to prevent stress from impairing synaptic plasticity in the prefrontal cortex and hippocampus. Tianeptine also has memory-protective characteristics, as it blocks the adverse effects of stress on hippocampus-dependent learning and memory. We have further extended the findings on stress, memory and tianeptine here with two novel observations: 1) stress impairs spatial memory in adrenalectomized (ADX), thereby corticosterone-depleted, rats; and 2) the stress-induced impairment of memory in ADX rats is blocked by tianeptine. These findings are consistent with previous research which indicates that tianeptine produces anti-stress and memory-protective properties without altering the response of the hypothalamic-pituitary-adrenal axis to stress. We conclude with a discussion of findings which indicate that tianeptine accomplishes its anti-stress effects by normalizing stress-induced increases in glutamate in the hippocampus and amygdala. This finding is potentially relevant to recent research which indicates that abnormalities in glutamatergic neurotransmission are involved in the pathogenesis of depression. Ultimately, tianeptine’s prevention of depression-induced sequelae in the brain is likely to be a primary factor in its effectiveness as a pharmacological treatment for depression.
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94
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Bloss EB, Janssen WG, McEwen BS, Morrison JH. Interactive effects of stress and aging on structural plasticity in the prefrontal cortex. J Neurosci 2010; 30:6726-31. [PMID: 20463234 PMCID: PMC2888496 DOI: 10.1523/jneurosci.0759-10.2010] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 03/25/2010] [Indexed: 02/05/2023] Open
Abstract
Neuronal networks in the prefrontal cortex mediate the highest levels of cognitive processing and decision making, and the capacity to perform these functions is among the cognitive features most vulnerable to aging. Despite much research, the neurobiological basis of age-related compromised prefrontal function remains elusive. Many investigators have hypothesized that exposure to stress may accelerate cognitive aging, though few studies have directly tested this hypothesis and even fewer have investigated a neuronal basis for such effects. It is known that in young animals, stress causes morphological remodeling of prefrontal pyramidal neurons that is reversible. The present studies sought to determine whether age influences the reversibility of stress-induced morphological plasticity in rat prefrontal neurons. We hypothesized that neocortical structural resilience is compromised in normal aging. To directly test this hypothesis we used a well characterized chronic restraint stress paradigm, with an additional group allowed to recover from the stress paradigm, in 3-, 12-, and 20-month-old male rats. In young animals, stress induced reductions of apical dendritic length and branch number, which were reversed with recovery; in contrast, middle-aged and aged rats failed to show reversible morphological remodeling when subjected to the same stress and recovery paradigm. The data presented here provide evidence that aging is accompanied by selective impairments in long-term neocortical morphological plasticity.
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Affiliation(s)
- Erik B. Bloss
- Fishberg Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, and
| | - William G. Janssen
- Fishberg Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, and
| | - Bruce S. McEwen
- Laboratory of Neuroendocrinology, Rockefeller University, New York, New York 10021
| | - John H. Morrison
- Fishberg Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, and
- Department of Geriatrics and Adult Development, Mount Sinai School of Medicine, New York, New York 10029, and
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95
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HAMED SHERIFAA. THE RATIONALE FOR NEUROPROTECTION IN EPILEPSY: STEPS FORWARD FOR NEW THERAPEUTIC AND PREVENTIVE STRATEGIES. J Integr Neurosci 2010. [DOI: 10.1142/s0219635210002378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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96
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Hajszan T, Szigeti-Buck K, Sallam NL, Bober J, Parducz A, MacLusky NJ, Leranth C, Duman RS. Effects of estradiol on learned helplessness and associated remodeling of hippocampal spine synapses in female rats. Biol Psychiatry 2010; 67:168-74. [PMID: 19811775 PMCID: PMC2794927 DOI: 10.1016/j.biopsych.2009.08.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 08/12/2009] [Accepted: 08/15/2009] [Indexed: 01/18/2023]
Abstract
BACKGROUND Despite the fact that women are twice as likely to develop depression as men, our understanding of depression neurobiology in female subjects is limited. We have recently reported in male rats that development of helpless behavior is associated with a severe loss of hippocampal spine synapses, which is reversed by treatment with the antidepressant desipramine. Considering that estradiol has a hippocampal synaptogenic effect similar to those of antidepressants, the presence of estradiol during the female reproductive life might influence behavioral and synaptic responses to stress and depression. METHODS With electron microscopic stereology, we analyzed hippocampal spine synapses in association with helpless behavior in ovariectomized female rats (n = 70), under different conditions of estradiol exposure. RESULTS Stress induced an acute and persistent loss of hippocampal spine synapses, whereas subchronic treatment with desipramine reversed the stress-induced synaptic loss. Estradiol supplementation given either before stress or before escape testing of nonstressed animals increased the number of hippocampal spine synapses. Correlation analysis demonstrated a statistically significant negative correlation between the severity of helpless behavior and hippocampal spine synapse numbers. CONCLUSIONS These findings suggest that hippocampal spine synapse remodeling might be a critical factor underlying learned helplessness and, possibly, the neurobiology of depression.
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Affiliation(s)
- Tibor Hajszan
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
| | - Klara Szigeti-Buck
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine; New Haven, CT 06520, USA,Department of Pharmacology, Yale University School of Medicine; New Haven, CT 06520, USA
| | - Nermin L Sallam
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine; New Haven, CT 06520, USA
| | - Jeremy Bober
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine; New Haven, CT 06520, USA
| | - Arpad Parducz
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Neil J MacLusky
- Department of Biomedical Sciences, Ontario Veterinary College, Guelph, Ontario, Canada N1G 2W1
| | - Csaba Leranth
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine; New Haven, CT 06520, USA,Department of Neurobiology; Yale University School of Medicine; New Haven, CT 06520, USA
| | - Ronald S Duman
- Department of Pharmacology, Yale University School of Medicine; New Haven, CT 06520, USA,Department of Psychiatry; Yale University School of Medicine; New Haven, CT 06520, USA
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97
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Bisaz R, Sandi C. The role of NCAM in auditory fear conditioning and its modulation by stress: a focus on the amygdala. GENES BRAIN AND BEHAVIOR 2010; 9:353-64. [DOI: 10.1111/j.1601-183x.2010.00563.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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98
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Rothman SM, Mattson MP. Adverse stress, hippocampal networks, and Alzheimer's disease. Neuromolecular Med 2009; 12:56-70. [PMID: 19943124 DOI: 10.1007/s12017-009-8107-9] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 11/06/2009] [Indexed: 12/13/2022]
Abstract
Recent clinical data have implicated chronic adverse stress as a potential risk factor in the development of Alzheimer's disease (AD) and data also suggest that normal, physiological stress responses may be impaired in AD. It is possible that pathology associated with AD causes aberrant responses to chronic stress, due to potential alterations in the hypothalamic-pituitary-adrenal (HPA) axis. Recent study in rodent models of AD suggests that chronic adverse stress exacerbates the cognitive deficits and hippocampal pathology that are present in the AD brain. This review summarizes recent findings obtained in experimental AD models regarding the influence of chronic adverse stress on the underlying cellular and molecular disease processes including the potential role of glucocorticoids. Emerging findings suggest that both AD and chronic adverse stress affect hippocampal neural networks in a similar fashion. We describe alterations in hippocampal plasticity, which occur in both chronic stress and AD including dendritic remodeling, neurogenesis, and long-term potentiation. Finally, we outline potential roles for oxidative stress and neurotrophic factor signaling as the key determinants of the impact of chronic stress on the plasticity of neural networks and AD pathogenesis.
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Affiliation(s)
- Sarah M Rothman
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, USA.
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99
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Gilbert PE, Brushfield AM. The role of the CA3 hippocampal subregion in spatial memory: a process oriented behavioral assessment. Prog Neuropsychopharmacol Biol Psychiatry 2009; 33:774-81. [PMID: 19375477 PMCID: PMC2743458 DOI: 10.1016/j.pnpbp.2009.03.037] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Accepted: 03/30/2009] [Indexed: 10/20/2022]
Abstract
Computational models, behavioral data, and electrophysiological data suggest that the CA3 subregion of the hippocampus may support multiple mnemonic processes critical to the formation and subsequent retrieval of spatial memories. Multiple researchers have proposed that the CA3 subregion contains an autoassociative network in which synaptic connections between CA3 neurons that represent different components of a memory are strengthened via recurrent collateral connections. As a result, it has been suggested that the CA3 autoassociative network may support multiple processes including the formation of spatial arbitrary associations, temporary maintenance of spatial working memory, and spatial pattern completion. In addition, the CA3 subregion has been suggested to be involved in spatial pattern separation. The separation of patterns is hypothesized to be accomplished based on the low probability that any two CA3 neurons will receive mossy-fiber input synapses from a similar subset of dentate gyrus cells. The separation of patterns also may be enhanced by competitive inhibition within CA3 and dentate gyrus. This review will focus on the mnemonic processes supported by CA3 neurons and how these processes may facilitate the encoding and retrieval of spatial information. Although there is growing evidence indicating that the hippocampus plays a role in the processing of nonspatial information as well, the scope of the present review will focus on the role of the CA3 subregion in spatial memory.
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Affiliation(s)
- Paul E. Gilbert
- Department of Psychology, San Diego State University, San Diego CA,San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego CA
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100
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McLaughlin KJ, Baran SE, Conrad CD. Chronic stress- and sex-specific neuromorphological and functional changes in limbic structures. Mol Neurobiol 2009; 40:166-82. [PMID: 19653136 DOI: 10.1007/s12035-009-8079-7] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 07/01/2009] [Indexed: 12/21/2022]
Abstract
Chronic stress produces sex-specific neuromorphological changes in a variety of brain regions, which likely contribute to the gender differences observed in stress-related illnesses and cognitive ability. Here, we review the literature investigating the relationship between chronic stress and sex differences on brain plasticity and function, with an emphasis on morphological changes in dendritic arborization and spines in the hippocampus, prefrontal cortex, and amygdala. These brain structures are highly interconnected and sensitive to stress and gonadal hormones, and influence a variety of cognitive abilities. Although much less work has been published using female subjects than with male subjects, the findings suggest that the relationship between brain morphology and function is very different between the sexes. After reviewing the literature, we present a model showing how chronic stress influences the morphology of these brain regions and changes the dynamic of how these limbic structures interact with each other to produce altered behavioral outcomes in spatial ability, behavioral flexibility/executive function, and emotional arousal.
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