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Abstract
11-beta-hydroxysteroid dehydrogenases (11β-HSDs) catalyse the conversion of active 11-hydroxy glucocorticoids (cortisol, corticosterone) and their inert 11-keto forms (cortisone, 11-dehydrocorticosterone). They were first reported in the body and brain 70 years ago, but only recently have they become of interest. 11β-HSD2 is a dehydrogenase, potently inactivating glucocorticoids. In the kidney, 11β-HSD2 generates the aldosterone-specificity of intrinsically non-selective mineralocorticoid receptors. 11β-HSD2 also protects the developing foetal brain and body from premature glucocorticoid exposure, which otherwise engenders the programming of neuropsychiatric and cardio-metabolic disease risks. In the adult CNS, 11β-HSD2 is confined to a part of the brain stem where it generates aldosterone-specific central control of salt appetite and perhaps blood pressure. 11β-HSD1 is a reductase, amplifying active glucocorticoid levels within brain cells, notably in the cortex, hippocampus and amygdala, paralleling its metabolic functions in peripheral tissues. 11β-HSD1 is elevated in the ageing rodent and, less certainly, human forebrain. Transgenic models show this rise contributes to age-related cognitive decline, at least in mice. 11β-HSD1 inhibition robustly improves memory in healthy and pathological ageing rodent models and is showing initial promising results in phase II studies of healthy elderly people. Larger trials are needed to confirm and clarify the magnitude of effect and define target populations. The next decade will be crucial in determining how this tale ends - in new treatments or disappointment.
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Affiliation(s)
- Jonathan Seckl
- Centre for Cardiovascular Sciences, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
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2
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Cade S, Zhou XF, Bobrovskaya L. The role of brain-derived neurotrophic factor and the neurotrophin receptor p75NTR in age-related brain atrophy and the transition to Alzheimer's disease. Rev Neurosci 2022; 33:515-529. [PMID: 34982865 DOI: 10.1515/revneuro-2021-0111] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/11/2021] [Indexed: 11/15/2022]
Abstract
Alzheimer's disease is a neurodegenerative condition that is potentially mediated by synaptic dysfunction before the onset of cognitive impairments. The disease mostly affects elderly people and there is currently no therapeutic which halts its progression. One therapeutic strategy for Alzheimer's disease is to regenerate lost synapses by targeting mechanisms involved in synaptic plasticity. This strategy has led to promising drug candidates in clinical trials, but further progress needs to be made. An unresolved problem of Alzheimer's disease is to identify the molecular mechanisms that render the aged brain susceptible to synaptic dysfunction. Understanding this susceptibility may identify drug targets which could halt, or even reverse, the disease's progression. Brain derived neurotrophic factor is a neurotrophin expressed in the brain previously implicated in Alzheimer's disease due to its involvement in synaptic plasticity. Low levels of the protein increase susceptibility to the disease and post-mortem studies consistently show reductions in its expression. A desirable therapeutic approach for Alzheimer's disease is to stimulate the expression of brain derived neurotrophic factor and potentially regenerate lost synapses. However, synthesis and secretion of the protein are regulated by complex activity-dependent mechanisms within neurons, which makes this approach challenging. Moreover, the protein is synthesised as a precursor which exerts the opposite effect of its mature form through the neurotrophin receptor p75NTR. This review will evaluate current evidence on how age-related alterations in the synthesis, processing and signalling of brain derived neurotrophic factor may increase the risk of Alzheimer's disease.
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Affiliation(s)
- Shaun Cade
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Xin-Fu Zhou
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Larisa Bobrovskaya
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
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3
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Noyes NC, Phan A, Davis RL. Memory suppressor genes: Modulating acquisition, consolidation, and forgetting. Neuron 2021; 109:3211-3227. [PMID: 34450024 PMCID: PMC8542634 DOI: 10.1016/j.neuron.2021.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/15/2021] [Accepted: 07/30/2021] [Indexed: 02/06/2023]
Abstract
The brain has a remarkable but underappreciated capacity to limit memory formation and expression. The term "memory suppressor gene" was coined in 1998 as an attempt to explain emerging reports that some genes appeared to limit memory. At that time, only a handful of memory suppressor genes were known, and they were understood to work by limiting cAMP-dependent consolidation. In the intervening decades, almost 100 memory suppressor genes with diverse functions have been discovered that affect not only consolidation but also acquisition and forgetting. Here we highlight the surprising extent to which biological limits are placed on memory formation through reviewing the literature on memory suppressor genes. In this review, we present memory suppressors within the framework of their actions on different memory operations: acquisition, consolidation, and forgetting. This is followed by a discussion of the reasons why there may be a biological need to limit memory formation.
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Affiliation(s)
- Nathaniel C Noyes
- Department of Neuroscience, Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Anna Phan
- Department of Biological Sciences, University of Alberta, 11355 Saskatchewan Drive, Edmonton, AB T6G 2E9, Canada
| | - Ronald L Davis
- Department of Neuroscience, Scripps Research Institute Florida, Jupiter, FL 33458, USA.
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4
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Bini J, Bhatt S, Hillmer AT, Gallezot JD, Nabulsi N, Pracitto R, Labaree D, Kapinos M, Ropchan J, Matuskey D, Sherwin RS, Jastreboff AM, Carson RE, Cosgrove K, Huang Y. Body Mass Index and Age Effects on Brain 11β-Hydroxysteroid Dehydrogenase Type 1: a Positron Emission Tomography Study. Mol Imaging Biol 2021; 22:1124-1131. [PMID: 32133575 DOI: 10.1007/s11307-020-01490-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
CONTEXT Cortisol, a glucocorticoid steroid stress hormone, is primarily responsible for stimulating gluconeogenesis in the liver and promoting adipocyte differentiation and maturation. Prolonged excess cortisol leads to visceral adiposity, insulin resistance, hyperglycemia, memory dysfunction, cognitive impairment, and more severe Alzheimer's disease phenotypes. The intracellular enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the conversion of inactive cortisone to active cortisol; yet the amount of 11β-HSD1 in the brain has not been quantified directly in vivo. OBJECTIVE We analyzed positron emission tomography (PET) scans with an 11β-HSD1 inhibitor radioligand in twenty-eight individuals (23 M/5F): 10 lean, 13 overweight, and 5 obese individuals. Each individual underwent PET imaging on the high-resolution research tomograph PET scanner after injection of 11C-AS2471907 (n = 17) or 18F-AS2471907 (n = 11). Injected activity and mass doses were 246 ± 130 MBq and 0.036 ± 0.039 μg, respectively, for 11C-AS2471907, and 92 ± 15 MBq and 0.001 ± 0.001 μg for 18F-AS2471907. Correlations of mean whole brain and regional distribution volume (VT) with body mass index (BMI) and age were performed with a linear regression model. RESULTS Significant correlations of whole brain mean VT with BMI and age (VT = 15.23-0.63 × BMI + 0.27 × Age, p = 0.001) were revealed. Age-adjusted mean whole brain VT values were significantly lower in obese individuals. Post hoc region specific analyses revealed significantly reduced mean VT values in the thalamus (lean vs. overweight and lean vs. obese individuals). Caudate, hypothalamus, parietal lobe, and putamen also showed lower VT value in obese vs. lean individuals. A significant age-associated increase of 2.7 mL/cm3 per decade was seen in BMI-corrected mean whole brain VT values. CONCLUSIONS In vivo PET imaging demonstrated, for the first time, correlation of higher BMI (obesity) with lower levels of the enzyme 11β-HSD1 in the brain and correlation of increased 11β-HSD1 levels in the brain with advancing age.
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Affiliation(s)
- Jason Bini
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA. .,Yale University PET Center, 801 Howard Ave, PO Box 208048, New Haven, CT, 06520-8048, USA.
| | - Shivani Bhatt
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Ansel T Hillmer
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA.,Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Jean-Dominique Gallezot
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Nabeel Nabulsi
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Richard Pracitto
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - David Labaree
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Michael Kapinos
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Jim Ropchan
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - David Matuskey
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA.,Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA.,Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Robert S Sherwin
- Department of Internal Medicine, Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Ania M Jastreboff
- Department of Internal Medicine, Endocrinology, Yale University School of Medicine, New Haven, CT, USA.,Department of Pediatrics, Pediatric Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Richard E Carson
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Kelly Cosgrove
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA.,Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Yiyun Huang
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
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Petschner P, Tamasi V, Adori C, Kirilly E, Ando RD, Tothfalusi L, Bagdy G. Gene expression analysis indicates reduced memory and cognitive functions in the hippocampus and increase in synaptic reorganization in the frontal cortex 3 weeks after MDMA administration in Dark Agouti rats. BMC Genomics 2018; 19:580. [PMID: 30071829 PMCID: PMC6090855 DOI: 10.1186/s12864-018-4929-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/05/2018] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") is a widely used entactogenic drug known to impair cognitive functions on the long-run. Both hippocampal and frontal cortical regions have well established roles in behavior, memory formation and other cognitive tasks and damage of these regions is associated with altered behavior and cognitive functions frequently described in otherwise healthy MDMA users. Meanwhile, in post-traumatic stress disorder (PTSD) patients seem to benefit from therapeutic application of the drug, where damage in hippocampal cue extinction may play a role. The aim of this study was to examine the hippocampus, frontal cortex and dorsal raphe of Dark Agouti rats with gene expression arrays (Illumina RatRef bead arrays) looking for possible mechanisms and new candidates contributing to the consequences of a single dose of MDMA (15 mg/kg) 3 weeks earlier. RESULTS The number of differentially expressed genes in the hippocampus, frontal cortex and the dorsal raphe were 481, 155, and 15, respectively. Gene set enrichment analysis of the microarray data revealed reduced expression of 'memory' and 'cognition', 'dendrite development' and 'regulation of synaptic plasticity' gene sets in the hippocampus, parallel to the downregulation of CaMK II subunits, glutamate-, CB1 cannabinoid- and EphA4, EphA5, EphA6 receptors. Downregulated gene sets in the frontal cortex were related to protein synthesis, chromatin organization, transmembrane transport processes, while 'dendrite development', 'regulation of synaptic plasticity' and 'positive regulation of synapse assembly' gene sets were upregulated besides elevated levels of a CaMK II subunit and NMDA2B glutamate receptor. Changes in the dorsal raphe region were mild and in most cases not significant. CONCLUSION The present data raise the possibility of new synapse formation / synaptic reorganization in the frontal cortex 3 weeks after a single neurotoxic dose of MDMA. In contrast, a prolonged depression of new neurite formation in the hippocampus is proposed by downregulations of members in long-term potentiation pathway and synaptic plasticity emphasizing the particular vulnerability of this brain region and proposing a mechanism responsible for cognitive problems in healthy individuals. At the same time, these results underpin benefits of MDMA in PTSD, where the drug may help memory extinction.
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Affiliation(s)
- Peter Petschner
- Department of Pharmacodynamics, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary.,MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, Nagyvarad ter 4., Budapest, H-1089, Hungary
| | - Viola Tamasi
- Department of Genetics, Cell- and Immunobiology, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary
| | - Csaba Adori
- Department of Pharmacodynamics, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary.,4 Retzius Laboratory, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177, Stockholm, Sweden
| | - Eszter Kirilly
- Department of Pharmacodynamics, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary
| | - Romeo D Ando
- Department of Pharmacodynamics, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary
| | - Laszlo Tothfalusi
- Department of Pharmacodynamics, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary
| | - Gyorgy Bagdy
- Department of Pharmacodynamics, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary. .,MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, Nagyvarad ter 4., Budapest, H-1089, Hungary. .,NAP-2-SE New Antidepressant Target Research Group, Semmelweis University, Nagyvarad ter 4., Budapest, H-1089, Hungary.
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6
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Wheelan N, Kenyon CJ, Harris AP, Cairns C, Al Dujaili E, Seckl JR, Yau JL. Midlife stress alters memory and mood-related behaviors in old age: Role of locally activated glucocorticoids. Psychoneuroendocrinology 2018; 89:13-22. [PMID: 29306773 PMCID: PMC5890827 DOI: 10.1016/j.psyneuen.2017.12.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 11/20/2022]
Abstract
Chronic exposure to stress during midlife associates with subsequent age-related cognitive decline and may increase the vulnerability to develop psychiatric conditions. Increased hypothalamic-pituitary-adrenal (HPA) axis activity has been implicated in pathogenesis though any causative role for glucocorticoids is unestablished. This study investigated the contribution of local glucocorticoid regeneration by the intracellular enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), in persisting midlife stress-induced behavioral effects in mice. Middle-aged (10 months old) 11β-HSD1-deficient mice and wild-type congenic controls were randomly assigned to 28 days of chronic unpredictable stress or left undisturbed (non-stressed). All mice underwent behavioral testing at the end of the stress/non-stress period and again 6-7 months later. Chronic stress impaired spatial memory in middle-aged wild-type mice. The effects, involving a wide spectrum of behavioral modalities, persisted for 6-7 months after cessation of stress into early senescence. Enduring effects after midlife stress included impaired spatial memory, enhanced contextual fear memory, impaired fear extinction, heightened anxiety, depressive-like behavior, as well as reduced hippocampal glucocorticoid receptor mRNA expression. In contrast, 11β-HSD1 deficient mice resisted both immediate and enduring effects of chronic stress, despite similar stress-induced increases in systemic glucocorticoid activity during midlife stress. In conclusion, chronic stress in midlife exerts persisting effects leading to cognitive and affective dysfunction in old age via mechanisms that depend, at least in part, on brain glucocorticoids generated locally by 11β-HSD1. This finding supports selective 11β-HSD1 inhibition as a novel therapeutic target to ameliorate the long-term consequences of stress-related psychiatric disorders in midlife.
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Affiliation(s)
- Nicola Wheelan
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom,Centre for Cognitive Aging and Cognitive Epidemiology, University of Edinburgh, EH8 8JZ, United Kingdom
| | - Christopher J. Kenyon
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom
| | - Anjanette P. Harris
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom,Centre for Cognitive Aging and Cognitive Epidemiology, University of Edinburgh, EH8 8JZ, United Kingdom
| | - Carolynn Cairns
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom
| | - Emad Al Dujaili
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom
| | - Jonathan R. Seckl
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom,Centre for Cognitive Aging and Cognitive Epidemiology, University of Edinburgh, EH8 8JZ, United Kingdom
| | - Joyce L.W. Yau
- Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, United Kingdom,Centre for Cognitive Aging and Cognitive Epidemiology, University of Edinburgh, EH8 8JZ, United Kingdom,Corresponding author at: Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, United Kingdom.
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