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Torraville SE, Flynn CM, Kendall TL, Yuan Q. Life Experience Matters: Enrichment and Stress Can Influence the Likelihood of Developing Alzheimer's Disease via Gut Microbiome. Biomedicines 2023; 11:1884. [PMID: 37509523 PMCID: PMC10377385 DOI: 10.3390/biomedicines11071884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/21/2023] [Accepted: 06/30/2023] [Indexed: 07/30/2023] Open
Abstract
Alzheimer's disease (AD) is a chronic neurodegenerative disease, characterized by the presence of β-amyloid (Aβ) plaques and neurofibrillary tangles (NFTs) formed from abnormally phosphorylated tau proteins (ptau). To date, there is no cure for AD. Earlier therapeutic efforts have focused on the clinical stages of AD. Despite paramount efforts and costs, pharmaceutical interventions including antibody therapies targeting Aβ have largely failed. This highlights the need to alternate treatment strategies and a shift of focus to early pre-clinical stages. Approximately 25-40% of AD cases can be attributed to environmental factors including chronic stress. Gut dysbiosis has been associated with stress and the pathogenesis of AD and can increase both Aβ and NFTs in animal models of the disease. Both stress and enrichment have been shown to alter AD progression and gut health. Targeting stress-induced gut dysbiosis through probiotic supplementation could provide a promising intervention to delay disease progression. In this review, we discuss the effects of stress, enrichment, and gut dysbiosis in AD models and the promising evidence from probiotic intervention studies.
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Affiliation(s)
- Sarah E Torraville
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL A1B 3V6, Canada
| | - Cassandra M Flynn
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL A1B 3V6, Canada
| | - Tori L Kendall
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL A1B 3V6, Canada
| | - Qi Yuan
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL A1B 3V6, Canada
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2
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Milligan Armstrong A, Porter T, Quek H, White A, Haynes J, Jackaman C, Villemagne V, Munyard K, Laws SM, Verdile G, Groth D. Chronic stress and Alzheimer's disease: the interplay between the hypothalamic-pituitary-adrenal axis, genetics and microglia. Biol Rev Camb Philos Soc 2021; 96:2209-2228. [PMID: 34159699 DOI: 10.1111/brv.12750] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 12/21/2022]
Abstract
Chronic psychosocial stress is increasingly being recognised as a risk factor for sporadic Alzheimer's disease (AD). The hypothalamic-pituitary-adrenal axis (HPA axis) is the major stress response pathway in the body and tightly regulates the production of cortisol, a glucocorticoid hormone. Dysregulation of the HPA axis and increased levels of cortisol are commonly found in AD patients and make a major contribution to the disease process. The underlying mechanisms remain poorly understood. In addition, within the general population there are interindividual differences in sensitivities to glucocorticoid and stress responses, which are thought to be due to a combination of genetic and environmental factors. These differences could ultimately impact an individuals' risk of AD. The purpose of this review is first to summarise the literature describing environmental and genetic factors that can impact an individual's HPA axis reactivity and function and ultimately AD risk. Secondly, we propose a mechanism by which genetic factors that influence HPA axis reactivity may also impact inflammation, a key driver of neurodegeneration. We hypothesize that these factors can mediate glucocorticoid priming of the immune cells of the brain, microglia, to become pro-inflammatory and promote a neurotoxic environment resulting in neurodegeneration. Understanding the underlying molecular mechanisms and identifying these genetic factors has implications for evaluating stress-related risk/progression to neurodegeneration, informing the success of interventions based on stress management and potential risks associated with the common use of glucocorticoids.
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Affiliation(s)
- Ayeisha Milligan Armstrong
- Curtin Health Innovation Research Institute, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia
| | - Tenielle Porter
- Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Collaborative Genomics and Translation Group, School of Medical and Health Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia
| | - Hazel Quek
- QIMR Berghofer Medical Institute, 300 Herston Rd, Herston, QLD, Australia
| | - Anthony White
- QIMR Berghofer Medical Institute, 300 Herston Rd, Herston, QLD, Australia
| | - John Haynes
- Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Connie Jackaman
- Curtin Health Innovation Research Institute, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia
| | - Victor Villemagne
- School of Medical and Health Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia.,The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Kylie Munyard
- Curtin Health Innovation Research Institute, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia
| | - Simon M Laws
- Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Collaborative Genomics and Translation Group, School of Medical and Health Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia
| | - Giuseppe Verdile
- Curtin Health Innovation Research Institute, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia.,School of Medical and Health Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia
| | - David Groth
- Curtin Health Innovation Research Institute, Curtin University, Kent St, Bentley, WA, 6102, Australia.,Curtin Medical School, Curtin University, Kent St, Bentley, WA, 6102, Australia
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3
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Wang Y, Wang Q, Chen J, Yao LH, Tang N, Jiang ZX, Luo Y. Protective Effect of Hydroxysafflor Yellow A against Chronic Mild Stress-induced Memory Impairments by Suppressing Tau Phosphorylation in Mice. Curr Med Sci 2021; 41:555-564. [PMID: 34129201 DOI: 10.1007/s11596-021-2369-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 09/10/2020] [Indexed: 12/19/2022]
Abstract
Chronic stress plays a critical role in the etiology of sporadic Alzheimer's disease (AD). However, there are currently no effective drugs that can target chronic stress to prevent AD. In this study, we explored the neuroprotective effect of hydroxysafflor yellow A (HSYA) against chronic mild stress (CMS)-induced memory impairments in mice and the underlying mechanism. The Morris water maze test showed that HSYA significantly reduced CMS-induced learning and memory impairments in mice. HSYA increased the expression of brain-derived neurotrophic factor (BDNF) and activated downstream tropomyosin-related kinase B (TrkB) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B(Akt)/mammalian target of rapamycin (mTOR) signaling. HSYA decreased the expression of regulator of calcineurin 1-1L (RCAN1-1L) that could promote the activity of glycogen synthase kinase-3β (GSK-3β). HSYA also attenuated tau phosphorylation by inhibiting the activity of GSK-3β and cyclin-dependent kinase-5 (Cdk5). Our data indicated that HSYA has protective effects against CMS-induced BDNF downregulation, tau phosphorylation and memory impairments. HSYA may be a promising therapeutic candidate for AD by targeting chronic stress.
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Affiliation(s)
- Ying Wang
- Department of Neurology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Qiang Wang
- Department of Neurology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Jun Chen
- Department of Neurology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Li-He Yao
- Department of Neurology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Ni Tang
- Department of Neurology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Zhen-Xiu Jiang
- Department of Neurology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Yu Luo
- Institute of Pathophysiology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China.
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4
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Honig MG, Dorian CC, Worthen JD, Micetich AC, Mulder IA, Sanchez KB, Pierce WF, Del Mar NA, Reiner A. Progressive long-term spatial memory loss following repeat concussive and subconcussive brain injury in mice, associated with dorsal hippocampal neuron loss, microglial phenotype shift, and vascular abnormalities. Eur J Neurosci 2020; 54:5844-5879. [PMID: 32090401 PMCID: PMC7483557 DOI: 10.1111/ejn.14711] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/14/2022]
Abstract
There is considerable concern about the long‐term deleterious effects of repeat head trauma on cognition, but little is known about underlying mechanisms and pathology. To examine this, we delivered four air blasts to the left side of the mouse cranium, a week apart, with an intensity that causes deficits when delivered singly and considered “concussive,” or an intensity that does not yield significant deficits when delivered singly and considered “subconcussive.” Neither repeat concussive nor subconcussive blast produced spatial memory deficits at 4 months, but both yielded deficits at 14 months, and dorsal hippocampal neuron loss. Hierarchical cluster analysis of dorsal hippocampal microglia across the three groups based on morphology and expression of MHCII, CX3CR1, CD68 and IBA1 revealed five distinct phenotypes. Types 1A and 1B microglia were more common in sham mice, linked to better neuron survival and memory, and appeared mildly activated. By contrast, 2B and 2C microglia were more common in repeat concussive and subconcussive mice, linked to poorer neuron survival and memory, and characterized by low expression levels and attenuated processes, suggesting they were de‐activated and dysfunctional. In addition, endothelial cells in repeat concussive mice exhibited reduced CD31 and eNOS expression, which was correlated with the prevalence of type 2B and 2C microglia. Our findings suggest that both repeat concussive and subconcussive head injury engender progressive pathogenic processes, possibly through sustained effects on microglia that over time lead to increased prevalence of dysfunctional microglia, adversely affecting neurons and blood vessels, and thereby driving neurodegeneration and memory decline.
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Affiliation(s)
- Marcia G Honig
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Conor C Dorian
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - John D Worthen
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Anthony C Micetich
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Isabelle A Mulder
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Katelyn B Sanchez
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - William F Pierce
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Nobel A Del Mar
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Anton Reiner
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA.,Department of Ophthalmology, The University of Tennessee Health Science Center, Memphis, TN, USA
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5
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Enhanced Molecular Appreciation of Psychiatric Disorders Through High-Dimensionality Data Acquisition and Analytics. Methods Mol Biol 2019; 2011:671-723. [PMID: 31273728 DOI: 10.1007/978-1-4939-9554-7_39] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The initial diagnosis, molecular investigation, treatment, and posttreatment care of major psychiatric disorders (schizophrenia and bipolar depression) are all still significantly hindered by the current inability to define these disorders in an explicit molecular signaling manner. High-dimensionality data analytics, using large datastreams from transcriptomic, proteomic, or metabolomic investigations, will likely advance both the appreciation of the molecular nature of major psychiatric disorders and simultaneously enhance our ability to more efficiently diagnose and treat these debilitating conditions. High-dimensionality data analysis in psychiatric research has been heterogeneous in aims and methods and limited by insufficient sample sizes, poorly defined case definitions, methodological inhomogeneity, and confounding results. All of these issues combine to constrain the conclusions that can be extracted from them. Here, we discuss possibilities for overcoming methodological challenges through the implementation of transcriptomic, proteomic, or metabolomics signatures in psychiatric diagnosis and offer an outlook for future investigations. To fulfill the promise of intelligent high-dimensionality data-based differential diagnosis in mental disease diagnosis and treatment, future research will need large, well-defined cohorts in combination with state-of-the-art technologies.
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6
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Tang W, Cheng J, Wang ZY, Chen KY, Han ZM, Wang QH, Yao YY. The Synergistic Roles of the Chronic Prenatal and Offspring Stress Exposures in Impairing Offspring Learning and Memory. J Alzheimers Dis 2016; 53:221-36. [PMID: 27128656 DOI: 10.3233/jad-160011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In Alzheimer's disease (AD), extensive experimental studies have demonstrated a negative impact of chronic stress during various stages of life (including prenatal phase) on some aspects of AD pathology. Nevertheless, presently, few studies have been involved in the learning and memory impairments, as well as neuropathology elicited by the chronic prenatal stress (CPS) and the chronic offspring stress (COS) exposures simultaneously, particularly for the adult male APPswe/PS1dE9 murine offspring. Therefore, the aim of the present study was to investigate the influence of CPS on learning and memory impairments induced by COS in 6-month-old male APPswe/PS1dE9 offspring mice and the related mechanism. Our study firstly demonstrates that 14-day exposure to CPS could exacerbate the learning and memory impairments, as well as neuropathological damages in the CA3 regions of the hippocampus and cortex neurons, which is induced by the 28-day exposure to COS in 6-month-old male APPswe/PS1dE9 offspring mice. In addition, CPS could potentiate the production of AβPP, Aβ42, and corticosterone in 6-month-old male APPswe/PS1dE9 offspring that also suffer COS. In conclusion, our novel findings strongly implicate the synergistic roles of the CPS and COS exposures in impairing offspring learning and memory. Moreover, CPS potentiating the production of Aβ42 might be mediated by glucocorticoids through increasing the expression of APP and BACE1 gene.
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Affiliation(s)
- Wei Tang
- Department of Laboratory Medicine, the Second Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.,Department of Clinical Laboratory Medicine, School of Public Health, Anhui Medical University, Hefei, Anhui, China
| | - Juan Cheng
- Department of Laboratory Medicine, the Second Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Zheng-Yu Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Anhui Medical University, Hefei, Anhui, China
| | - Ke-Yang Chen
- Department of Clinical Laboratory Medicine, School of Public Health, Anhui Medical University, Hefei, Anhui, China
| | - Zhen-Min Han
- Department of Nutrition and Food Hygiene, School of Public Health, Anhui Medical University, Hefei, Anhui, China
| | - Qi-Hong Wang
- Hefei Meikang Medical Equipment Co., Ltd., Hefei, Anhui, China
| | - Yu-You Yao
- Department of Clinical Laboratory Medicine, School of Public Health, Anhui Medical University, Hefei, Anhui, China
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7
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Effects of an alpha7 nicotinic receptor agonist and stress on spatial memory in an animal model of Alzheimer's disease. BIOMED RESEARCH INTERNATIONAL 2013; 2013:952719. [PMID: 24058919 PMCID: PMC3766554 DOI: 10.1155/2013/952719] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 07/24/2013] [Accepted: 07/25/2013] [Indexed: 01/23/2023]
Abstract
The aim of the present study was to test the effects of PNU-282987 on spatial learning and memory and hippocampal neurogenesis in both intact and chronically stressed transgenic mice. Transgenic mice with susceptibility to Alzheimer's disease (AD) under immobilization stress and not-stressed animals receiving 0 and 1 mg/kg of PNU-282987 (PNU) were evaluated in a water maze task. The effects of PNU and stress on proliferation of new cells in the hippocampus of these animals were also assessed. The latency to escape the platform was significantly higher in transgenic stressed mice compared to those in the wild stressed group, as well as in transgenic animals without PNU compared to control wild group. On retention of the task, differences emerged on stressed wild animals, PNU wild group, and stressed wild mice receiving PNU. However, no significant differences were detected on new cell proliferation. The results of the present study did not show any impact of stress in acquisition of a spatial task both in wild and transgenic mice. No clear effects of PNU on acquisition of a spatial task in transgenic mice with susceptibility to AD were detected. Although PNU and stress effects were detected on retention of the task in wild animals, no changes were noted in transgenic mice.
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8
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Behavioral and neurobiological effects of prenatal stress exposure in male and female APPswe/PS1dE9 mice. Neurobiol Aging 2013; 34:319-37. [DOI: 10.1016/j.neurobiolaging.2012.05.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 05/21/2012] [Accepted: 05/21/2012] [Indexed: 11/18/2022]
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9
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Wang Y, Cheng Z, Qin W, Jia J. Val97Leu mutant presenilin-1 induces tau hyperphosphorylation and spatial memory deficit in mice and the underlying mechanisms. J Neurochem 2012; 121:135-45. [PMID: 21929538 DOI: 10.1111/j.1471-4159.2011.07489.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Although the pathological role of presenilin-1 mutation in early onset familial Alzheimer's disease has been widely studied, few focused on how the presenilin-1 mutations result in memory impairment and tau hyperphosphorylation. In the present study, we expressed human Val97Leu mutant presenilin-1, which is reported in Chinese pedigrees by our group, in transgenic mice and found that the mutant presenilin-1 induced spatial memory deficit and tau hyperphosphorylation at PHF-1, pS199/202, pT231 and pS396 epitopes, but not at pS214 and pS422 epitopes. Pearson analysis showed that the memory deficit was only significantly correlated with tau phosphorylation level at PHF-1, pS199/202, pT231 and pS396 epitopes. Additionally, the hyperphosphorylated tau and tangle-like argentophilic structures were detected at CA3 and CA4, but not CA1, region of hippocampus, and we also found tangle-like structure and wizened degenerative neurons in frontal cortex. We demonstrated the tau hyperphosphorylation at the same epitopes in N2a cells expressing the mutant presenilin-1, which is caused by inhibition of phosphoinositol-3 kinase/Akt and activation of glycogen synthase kinase-3 specifically. Our data demonstrated that human Val97Leu mutant presenilin-1 causes spatial memory deficit in mice and increases tau phosphorylation level in glycogen synthase kinase-3-dependent manner.
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Affiliation(s)
- Yue Wang
- Department of Neurology, Xuan Wu Hospital of the Capital Medical University, Beijing, China
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10
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Seo JS, Lee KW, Kim TK, Baek IS, Im JY, Han PL. Behavioral stress causes mitochondrial dysfunction via ABAD up-regulation and aggravates plaque pathology in the brain of a mouse model of Alzheimer disease. Free Radic Biol Med 2011; 50:1526-35. [PMID: 21382475 DOI: 10.1016/j.freeradbiomed.2011.02.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 02/11/2011] [Accepted: 02/25/2011] [Indexed: 10/18/2022]
Abstract
Basic and clinical studies have reported that behavioral stress worsens the pathology of Alzheimer disease (AD), but the underlying mechanism has not been clearly understood. In this study, we determined the mechanism by which behavioral stress affects the pathogenesis of AD using Tg-APPswe/PS1dE9 mice, a murine model of AD. Tg-APPswe/PS1dE9 mice that were restrained for 2h daily for 16 consecutive days (2-h/16-day stress) from 6.5months of age had significantly increased Aβ(1-42) levels and plaque deposition in the brain. The 2-h/16-day stress increased oxidative stress and induced mitochondrial dysfunction in the brain. Treatment with glucocorticoid (corticosterone) and Aβ in SH-SY5Y cells increased the expression of 17β-hydroxysteroid dehydrogenase (ABAD), mitochondrial dysfunction, and levels of ROS, whereas blockade of ABAD expression by siRNA-ABAD in SH-SY5Y cells suppressed glucocorticoid-enhanced mitochondrial dysfunction and ROS accumulation. The 2-h/16-day stress up-regulated ABAD expression in mitochondria in the brain of Tg-APPswe/PS1dE9 mice. Moreover, all visible Aβ plaques were costained with anti-ABAD in the brains of Tg-APPswe/PS1dE9 mice. Together, these results suggest that behavioral stress aggravates plaque pathology and mitochondrial dysfunction via up-regulation of ABAD in the brain of a mouse model of AD.
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Affiliation(s)
- Ji-Seon Seo
- Department of Brain and Cognitive Sciences, Ewha Women's University, Seoul 120-750, Republic of Korea
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11
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Stress, exercise, and Alzheimer's disease: a neurovascular pathway. Med Hypotheses 2011; 76:847-54. [PMID: 21398043 DOI: 10.1016/j.mehy.2011.02.034] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 02/16/2011] [Accepted: 02/20/2011] [Indexed: 12/16/2022]
Abstract
Genetic factors are known to play a role in Alzheimer's disease (AD) vulnerability, yet less than 1% of incident AD cases are directly linked to genetic causes, suggesting that environmental variables likely play a role in the majority of cases. Several recent human and animal studies have examined the effects of behavioral factors, specifically psychological stress and exercise, on AD vulnerability. Numerous animal studies have found that, while stress exacerbates neuropathological changes associated with AD, exercise reduces these changes. Some human studies suggest that psychological stress can increase the risk of developing AD, while other studies suggest that exercise can significantly reduce AD risk. Most animal studies investigating the mechanisms responsible for the effects of these behavioral factors have focused on neuronal processes, including the effects of stress hormones and neurotrophic factors on the neuropathological hallmarks of AD, namely amyloid-beta (Aβ) deposition and tau-phosphorylation. However, cumulative evidence indicates that, in humans, AD is associated with the presence of cerebrovascular disease, and cardiovascular risk factors are associated with increased risk of developing AD. There is an extensive literature demonstrating that behavioral factors, particularly stress and exercise, can powerfully modulate the pathophysiology of vascular disease. Thus, the following model proposes that the influence of stress and exercise on AD risk may be partially due to the effects of these behavioral factors on vascular homeostasis and pathology. These effects are likely due to both indirect modification of AD risk through alterations in vascular risk factors, such as hypertension, diabetes, and aortic stiffening, as well as direct influence on the cerebrovasculature, including changes in cerebral blood flow, angiogenesis, and vascular disease. Future studies examining the effects of behavioral factors on AD risk should incorporate measures of both peripheral and cerebral vascular function to further our understanding of the mechanisms by which behavior can modify AD susceptibility. Greater knowledge of the molecular mechanisms behind these behavioral effects would further our understanding of the disease and lead to innovative treatment and preventive approaches.
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12
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Huehnchen P, Prozorovski T, Klaissle P, Lesemann A, Ingwersen J, Wolf SA, Kupsch A, Aktas O, Steiner B. Modulation of adult hippocampal neurogenesis during myelin-directed autoimmune neuroinflammation. Glia 2010; 59:132-42. [DOI: 10.1002/glia.21082] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 08/31/2010] [Indexed: 01/04/2023]
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13
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Chouliaras L, Sierksma ASR, Kenis G, Prickaerts J, Lemmens MAM, Brasnjevic I, van Donkelaar EL, Martinez-Martinez P, Losen M, De Baets MH, Kholod N, van Leeuwen F, Hof PR, van Os J, Steinbusch HWM, van den Hove DLA, Rutten BPF. Gene-environment interaction research and transgenic mouse models of Alzheimer's disease. Int J Alzheimers Dis 2010; 2010. [PMID: 20953364 PMCID: PMC2952897 DOI: 10.4061/2010/859101] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Accepted: 07/31/2010] [Indexed: 01/08/2023] Open
Abstract
The etiology of the sporadic form of Alzheimer's disease (AD) remains largely unknown. Recent evidence has suggested that gene-environment interactions (GxE) may play a crucial role in its development and progression. Whereas various susceptibility loci have been identified, like the apolipoprotein E4 allele, these cannot fully explain the increasing prevalence of AD observed with aging. In addition to such genetic risk factors, various environmental factors have been proposed to alter the risk of developing AD as well as to affect the rate of cognitive decline in AD patients. Nevertheless, aside from the independent effects of genetic and environmental risk factors, their synergistic participation in increasing the risk of developing AD has been sparsely investigated, even though evidence points towards such a direction. Advances in the genetic manipulation of mice, modeling various aspects of the AD pathology, have provided an excellent tool to dissect the effects of genes, environment, and their interactions. In this paper we present several environmental factors implicated in the etiology of AD that have been tested in transgenic animal models of the disease. The focus lies on the concept of GxE and its importance in a multifactorial disease like AD. Additionally, possible mediating mechanisms and future challenges are discussed.
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Affiliation(s)
- L Chouliaras
- School for Mental Health and Neuroscience (MHeNS), Faculty of Health, Medicine and Life Sciences, European Graduate School of Neuroscience (EURON), Maastricht University Medical Centre, P.O. Box 616, 6200 MD Maastricht, The Netherlands
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