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Effects of aging and caloric restriction on brainstem satiety center signals in rats. Mech Ageing Dev 2012; 133:83-91. [PMID: 22285292 DOI: 10.1016/j.mad.2012.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 12/31/2011] [Accepted: 01/13/2012] [Indexed: 02/02/2023]
Abstract
Age-related increases of body weight and adiposity, indicating dysregulation of food intake/energy expenditure, can be prevented in rodents by long-term 40% caloric restriction. The dorsal vagal complex (DVC), the brainstem center mediating the satiety reflex, has recently emerged as a determinant effector of long-term feeding adaptation. To study the effects of aging and caloric restriction on satiety circuits, leptin and brain-derived neurotrophic factor (BDNF) signaling systems were studied in 2- and 19-month-old ad libitum-fed (AL) and 19-month-old calorie-restricted (CR) rats. Age-induced hyperleptinemia in AL rats was correlated with elevated DVC BDNF immunoreactive concentrations and satiety threshold stability, suggesting functional desensitization of the DVC to these signals. To better understand this phenomenon, mRNA levels of receptor and post-receptor signaling effectors were measured by real-time RT-PCR. Aging selectively increased BDNF receptors and suppressor of cytokine signaling-3 (SOCS-3) mRNA levels. Caloric restriction prevented age-related increases of serum leptin, DVC BDNF and SOCS-3 mRNA levels, but not those of BDNF receptors. In CR rats, prevention of leptin resistance-promoting SOCS-3 induction was also observed at the protein level. This study suggests that leptin post-receptor targets and BDNF signaling play a role in the establishment of age-related DVC dysfunction.
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202
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Stranahan AM, Mattson MP. Recruiting adaptive cellular stress responses for successful brain ageing. Nat Rev Neurosci 2012; 13:209-16. [PMID: 22251954 DOI: 10.1038/nrn3151] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Successful ageing is determined in part by genetic background, but also by experiential factors associated with lifestyle and culture. Dietary, behavioural and pharmacological interventions have been identified as potential means to slow brain ageing and forestall neurodegenerative disease. Many of these interventions recruit adaptive cellular stress responses to strengthen neuronal networks and enhance plasticity. In this Science and Society article, we describe several determinants of healthy and pathological brain ageing, with insights into how these processes are accelerated or prevented. We also describe the mechanisms underlying the neuroprotective actions of exercise and nutritional interventions, with the goal of recruiting these molecular targets for the treatment and prevention of neurodegenerative disease.
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Affiliation(s)
- Alexis M Stranahan
- Physiology Department, Georgia Health Sciences University, Augusta, Georgia 30912, USA
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203
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Stranahan AM, Martin B, Chadwick W, Park SS, Wang L, Becker KG, WoodIII WH, Zhang Y, Maudsley S. Metabolic context regulates distinct hypothalamic transcriptional responses to antiaging interventions. Int J Endocrinol 2012; 2012:732975. [PMID: 22934110 PMCID: PMC3427989 DOI: 10.1155/2012/732975] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 03/09/2012] [Indexed: 01/19/2023] Open
Abstract
The hypothalamus is an essential relay in the neural circuitry underlying energy metabolism that needs to continually adapt to changes in the energetic environment. The neuroendocrine control of food intake and energy expenditure is associated with, and likely dependent upon, hypothalamic plasticity. Severe disturbances in energy metabolism, such as those that occur in obesity, are therefore likely to be associated with disruption of hypothalamic transcriptomic plasticity. In this paper, we investigated the effects of two well-characterized antiaging interventions, caloric restriction and voluntary wheel running, in two distinct physiological paradigms, that is, diabetic (db/db) and nondiabetic wild-type (C57/Bl/6) animals to investigate the contextual sensitivity of hypothalamic transcriptomic responses. We found that, both quantitatively and qualitatively, caloric restriction and physical exercise were associated with distinct transcriptional signatures that differed significantly between diabetic and non-diabetic mice. This suggests that challenges to metabolic homeostasis regulate distinct hypothalamic gene sets in diabetic and non-diabetic animals. A greater understanding of how genetic background contributes to hypothalamic response mechanisms could pave the way for the development of more nuanced therapeutics for the treatment of metabolic disorders that occur in diverse physiological backgrounds.
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Affiliation(s)
- Alexis M. Stranahan
- Physiology Department, Georgia Health Sciences University, Augusta, GA 30912, USA
- *Alexis M. Stranahan:
| | - Bronwen Martin
- Metabolism Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - Wayne Chadwick
- Receptor Pharmacology Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - Sung-Soo Park
- Receptor Pharmacology Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - Liyun Wang
- Receptor Pharmacology Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - Kevin G. Becker
- Gene Expression and Genomics Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - William H. WoodIII
- Gene Expression and Genomics Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - Yongqing Zhang
- Gene Expression and Genomics Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
| | - Stuart Maudsley
- Receptor Pharmacology Unit, National Institute on Aging Intramural Research Program, Baltimore, MD 21224-6825, USA
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204
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Different types of exercise induce differential effects on neuronal adaptations and memory performance. Neurobiol Learn Mem 2012; 97:140-7. [DOI: 10.1016/j.nlm.2011.10.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/14/2011] [Accepted: 10/31/2011] [Indexed: 11/21/2022]
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205
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Cheng A, Wan R, Yang JL, Kamimura N, Son TG, Ouyang X, Luo Y, Okun E, Mattson MP. Involvement of PGC-1α in the formation and maintenance of neuronal dendritic spines. Nat Commun 2012; 3:1250. [PMID: 23212379 PMCID: PMC4091730 DOI: 10.1038/ncomms2238] [Citation(s) in RCA: 287] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 10/31/2012] [Indexed: 12/13/2022] Open
Abstract
The formation, maintenance and reorganization of synapses are critical for brain development and the responses of neuronal circuits to environmental challenges. Here we describe a novel role for peroxisome proliferator-activated receptor γ co-activator 1α, a master regulator of mitochondrial biogenesis, in the formation and maintenance of dendritic spines in hippocampal neurons. In cultured hippocampal neurons, proliferator-activated receptor γ co-activator 1α overexpression increases dendritic spines and enhances the molecular differentiation of synapses, whereas knockdown of proliferator-activated receptor γ co-activator 1α inhibits spinogenesis and synaptogenesis. Proliferator-activated receptor γ co-activator 1α knockdown also reduces the density of dendritic spines in hippocampal dentate granule neurons in vivo. We further show that brain-derived neurotrophic factor stimulates proliferator-activated receptor γ co-activator-1α-dependent mitochondrial biogenesis by activating extracellular signal-regulated kinases and cyclic AMP response element-binding protein. Proliferator-activated receptor γ co-activator-1α knockdown inhibits brain-derived neurotrophic factor-induced dendritic spine formation without affecting expression and activation of the brain-derived neurotrophic factor receptor tyrosine receptor kinase B. Our findings suggest that proliferator-activated receptor γ co-activator-1α and mitochondrial biogenesis have important roles in the formation and maintenance of hippocampal dendritic spines and synapses.
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Affiliation(s)
- Aiwu Cheng
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Ruiqian Wan
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Jenq-Lin Yang
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
- Laboratory of Molecular Gerontology, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Naomi Kamimura
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
- Department of Biochemistry and Cell Biology, Institute of Development and Aging Sciences, Graduate School of Medicine, Nippon Medical School, Kawasaki-city, 211-8533 Japan
| | - Tae Gen Son
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Xin Ouyang
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Yongquan Luo
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Eitan Okun
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Mark P. Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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206
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Stranahan AM, Martin B, Maudsley S. Anti-inflammatory effects of physical activity in relationship to improved cognitive status in humans and mouse models of Alzheimer's disease. Curr Alzheimer Res 2012; 9:86-92. [PMID: 22329653 PMCID: PMC4445413 DOI: 10.2174/156720512799015019] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 02/10/2011] [Accepted: 08/09/2011] [Indexed: 11/22/2022]
Abstract
Physical activity has been correlated with a reduced incidence of cognitive decline and Alzheimer's disease in human populations. Although data from intervention-based randomized trials is scarce, there is some indication that exercise may confer protection against age-related deficits in cognitive function. Data from animal models suggests that exercise, in the form of voluntary wheel running, is associated with reduced amyloid deposition and enhanced clearance of amyloid beta, the major constituent of plaques in Alzheimer's disease. Treadmill exercise has also been shown to ameliorate the accumulation of phosphorylated tau, an essential component of neurofibrillary tangles in Alzheimer's models. A common therapeutic theme arising from studies of exercise-induced neuroprotection in human populations and in animal models involves reduced inflammation in the central nervous system. In this respect, physical activity may promote neuronal resilience by reducing inflammation.
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Affiliation(s)
- Alexis M. Stranahan
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Bronwen Martin
- Metabolism Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore MD, USA
| | - Stuart Maudsley
- Receptor Pharmacology Unit, Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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207
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Bendlin B, Canu E, Willette A, Kastman E, McLaren D, Kosmatka K, Xu G, Field A, Colman R, Coe C, Weindruch R, Alexander A, Johnson S. Effects of aging and calorie restriction on white matter in rhesus macaques. Neurobiol Aging 2011; 32:2319.e1-11. [PMID: 20541839 PMCID: PMC2939965 DOI: 10.1016/j.neurobiolaging.2010.04.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 03/12/2010] [Accepted: 04/09/2010] [Indexed: 01/31/2023]
Abstract
Rhesus macaques on a calorie restricted diet (CR) develop less age-related disease, have virtually no indication of diabetes, are protected against sarcopenia, and potentially live longer. Beneficial effects of caloric restriction likely include reductions in age-related inflammation and oxidative damage. Oligodendrocytes are particularly susceptible to inflammation and oxidative stress, therefore, we hypothesized that CR would have a beneficial effect on brain white matter and would attenuate age-related decline in this tissue. CR monkeys and controls underwent diffusion tensor imaging (DTI). A beneficial effect of CR indexed by DTI was observed in superior longitudinal fasciculus, fronto-occipital fasciculus, external capsule, and brainstem. Aging effects were observed in several regions, although CR appeared to attenuate age-related alterations in superior longitudinal fasciculus, frontal white matter, external capsule, right parahippocampal white matter, and dorsal occipital bundle. The results, however, were regionally specific and also suggested that CR is not salutary across all white matter. Further evaluation of this unique cohort of elderly primates to mortality will shed light on the ultimate benefits of an adult-onset, moderate CR diet for deferring brain aging.
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Affiliation(s)
- B.B. Bendlin
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
| | - E. Canu
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
| | - A.A. Willette
- Harlow Primate Laboratory, Department of Psychology, Madison, WI, USA
- Wisconsin National Primate Research Center, Madison, WI
| | - E.K. Kastman
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
| | - D.G. McLaren
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
| | - K.J. Kosmatka
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
| | - G. Xu
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
| | - A.S. Field
- University of Wisconsin School of Medicine and Public Health, Department of Radiology, Madison, WI, USA
| | - R.J. Colman
- Wisconsin National Primate Research Center, Madison, WI
| | - C.L. Coe
- Harlow Primate Laboratory, Department of Psychology, Madison, WI, USA
- Wisconsin National Primate Research Center, Madison, WI
| | - R.H. Weindruch
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
- Wisconsin National Primate Research Center, Madison, WI
| | - A.L. Alexander
- University of Wisconsin School of Medicine and Public Health, Departments of Psychiatry and Medical Physics, Madison, WI, USA
- Waisman Laboratory for Brain Imaging and Behavior, Madison, WI, USA
| | - S.C. Johnson
- Geriatric Research Educational and Clinical Center, Wm. S. Middleton Memorial Veterans Hospital, Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Department of Medicine, Madison, WI, USA
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208
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Physical inactivity is a disease synonymous for a non-permissive brain disorder. Med Hypotheses 2011; 77:708-13. [DOI: 10.1016/j.mehy.2011.07.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 06/07/2011] [Accepted: 07/07/2011] [Indexed: 01/11/2023]
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209
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An overview of brain-derived neurotrophic factor and implications for excitotoxic vulnerability in the hippocampus. INTERNATIONAL JOURNAL OF PEPTIDES 2011; 2011:654085. [PMID: 21966294 PMCID: PMC3182334 DOI: 10.1155/2011/654085] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 07/26/2011] [Indexed: 01/19/2023]
Abstract
The present paper examines the nature and function of brain-derived neurotrophic factor (BDNF) in the hippocampal formation and the consequences of changes in its expression. The paper focuses on literature describing the role of BDNF in hippocampal development and neuroplasticity. BDNF expression is highly sensitive to developmental and environmental factors, and increased BDNF signaling enhances neurogenesis, neurite sprouting, electrophysiological activity, and other processes reflective of a general enhancement of hippocampal function. Such increases in activity may mediate beneficial effects such as enhanced learning and memory. However, the increased activity also comes at a cost: BDNF plasticity renders the hippocampus more vulnerable to hyperexcitability and/or excitotoxic damage. Exercise dramatically increases hippocampal BDNF levels and produces behavioral effects consistent with this phenomenon. In analyzing the literature regarding exercise-induced regulation of BDNF, this paper provides a theoretical model for how the potentially deleterious consequences of BDNF plasticity may be modulated by other endogenous factors. The peptide galanin may play such a role by regulating hippocampal excitability.
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210
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Dinel AL, André C, Aubert A, Ferreira G, Layé S, Castanon N. Cognitive and emotional alterations are related to hippocampal inflammation in a mouse model of metabolic syndrome. PLoS One 2011; 6:e24325. [PMID: 21949705 PMCID: PMC3174932 DOI: 10.1371/journal.pone.0024325] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 08/06/2011] [Indexed: 01/01/2023] Open
Abstract
Converging clinical data suggest that peripheral inflammation is likely involved in the pathogenesis of the neuropsychiatric symptoms associated with metabolic syndrome (MetS). However, the question arises as to whether the increased prevalence of behavioral alterations in MetS is also associated with central inflammation, i.e. cytokine activation, in brain areas particularly involved in controlling behavior. To answer this question, we measured in a mouse model of MetS, namely the diabetic and obese db/db mice, and in their healthy db/+ littermates emotional behaviors and memory performances, as well as plasma levels and brain expression (hippocampus; hypothalamus) of inflammatory cytokines. Our results shows that db/db mice displayed increased anxiety-like behaviors in the open-field and the elevated plus-maze (i.e. reduced percent of time spent in anxiogenic areas of each device), but not depressive-like behaviors as assessed by immobility time in the forced swim and tail suspension tests. Moreover, db/db mice displayed impaired spatial recognition memory (hippocampus-dependent task), but unaltered object recognition memory (hippocampus-independent task). In agreement with the well-established role of the hippocampus in anxiety-like behavior and spatial memory, behavioral alterations of db/db mice were associated with increased inflammatory cytokines (interleukin-1β, tumor necrosis factor-α and interleukin-6) and reduced expression of brain-derived neurotrophic factor (BDNF) in the hippocampus but not the hypothalamus. These results strongly point to interactions between cytokines and central processes involving the hippocampus as important contributing factor to the behavioral alterations of db/db mice. These findings may prove valuable for introducing novel approaches to treat neuropsychiatric complications associated with MetS.
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Affiliation(s)
- Anne-Laure Dinel
- Nutrition et Neurobiologie Intégrée, INRA UMR 1286, Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Caroline André
- Nutrition et Neurobiologie Intégrée, INRA UMR 1286, Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Agnès Aubert
- Nutrition et Neurobiologie Intégrée, INRA UMR 1286, Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Guillaume Ferreira
- Nutrition et Neurobiologie Intégrée, INRA UMR 1286, Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Sophie Layé
- Nutrition et Neurobiologie Intégrée, INRA UMR 1286, Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Nathalie Castanon
- Nutrition et Neurobiologie Intégrée, INRA UMR 1286, Bordeaux, France
- University of Bordeaux, Bordeaux, France
- * E-mail:
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211
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Kobilo T, Liu QR, Gandhi K, Mughal M, Shaham Y, van Praag H. Running is the neurogenic and neurotrophic stimulus in environmental enrichment. Learn Mem 2011; 18:605-9. [PMID: 21878528 DOI: 10.1101/lm.2283011] [Citation(s) in RCA: 278] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Environmental enrichment (EE) increases dentate gyrus (DG) neurogenesis and brain-derived neurotrophic factor (BDNF) levels. However, running is considered an element of EE. To dissociate effects of physical activity and enrichment on hippocampal neurogenesis and BDNF levels, young female C57Bl/6 mice were housed under control, running, enrichment, or enrichment plus running conditions, and injected with bromodeoxyuridine. Cell genesis was assessed after 12 d and differentiation was analyzed 1 mo later. In addition, locomotor activity in the open field and hippocampal mature BDNF peptide levels were measured. Open-field adaptation was improved in all groups, compared to controls, but more so with running. New cell proliferation, survival, neuron number, and neurotrophin levels were enhanced only when running was accessible. We conclude that exercise is the critical factor mediating increased BDNF levels and adult hippocampal neurogenesis.
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Affiliation(s)
- Tali Kobilo
- Neuroplasticity and Behavior Unit, Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, Baltimore, Maryland 21224, USA
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212
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Rothman SM, Herdener N, Camandola S, Texel SJ, Mughal MR, Cong WN, Martin B, Mattson MP. 3xTgAD mice exhibit altered behavior and elevated Aβ after chronic mild social stress. Neurobiol Aging 2011; 33:830.e1-12. [PMID: 21855175 DOI: 10.1016/j.neurobiolaging.2011.07.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 06/30/2011] [Accepted: 07/08/2011] [Indexed: 01/01/2023]
Abstract
Chronic stress may be a risk factor for developing Alzheimer's disease (AD), but most studies of the effects of stress in models of AD utilize acute adverse stressors of questionable clinical relevance. The goal of this work was to determine how chronic psychosocial stress affects behavioral and pathological outcomes in an animal model of AD, and to elucidate underlying mechanisms. A triple-transgenic mouse model of AD (3xTgAD mice) and nontransgenic control mice were used to test for an affect of chronic mild social stress on blood glucose, plasma glucocorticoids, plasma insulin, anxiety, and hippocampal amyloid β-particle (Aβ), phosphorylated tau (ptau), and brain-derived neurotrophic factor (BDNF) levels. Despite the fact that both control and 3xTgAD mice experienced rises in corticosterone during episodes of mild social stress, at the end of the 6-week stress period 3xTgAD mice displayed increased anxiety, elevated levels of Aβ oligomers and intraneuronal Aβ, and decreased brain-derived neurotrophic factor levels, whereas control mice did not. Findings suggest 3xTgAD mice are more vulnerable than control mice to chronic psychosocial stress, and that such chronic stress exacerbates Aβ accumulation and impairs neurotrophic signaling.
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Affiliation(s)
- Sarah M Rothman
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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213
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Ferreira AGK, Scherer EB, da Cunha MJ, Machado FR, Cunha AAD, Graeff JS, Netto CA, Wyse ATS. Physical exercise reverses cognitive impairment in rats subjected to experimental hyperprolinemia. Neurochem Res 2011; 36:2306-15. [PMID: 21792675 DOI: 10.1007/s11064-011-0555-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/12/2011] [Accepted: 07/14/2011] [Indexed: 12/20/2022]
Abstract
This study investigated whether physical exercise would reverse proline-induced performance deficits in water maze tasks, as well as its effects on brain-derived neurotrophic factor (BDNF) immunocontent and brain acetylcholinesterase (AChE) activity in Wistar rats. Proline administration followed partial time (6th-29th day of life) or full time (6th-60th day of life) protocols. Treadmill exercise was performed from 30th to 60th day of life, when behavioral testing was started. After that, animals were sacrificed for BDNF and AChE determination. Results show that proline impairs cognitive performance, decreases BDNF in cerebral cortex and hippocampus and increases AChE activity in hippocampus. All reported effects were prevented by exercise. These results suggest that cognitive, spatial learning/memory, deficits caused by hyperprolinemia may be associated, at least in part, to the decrease in BDNF levels and to the increase in AChE activity, as well as support the role of physical exercise as a potential neuroprotective strategy.
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Affiliation(s)
- Andréa G K Ferreira
- Laboratório de Neuroproteção e Doença Metabólica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 Anexo, Porto Alegre, RS, Brazil
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214
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Shi X, Lu XG, Zhan LB, Qi X, Liang LN, Hu SY, Yan Y, Zhao SY, Sui H, Zhang FL. The effects of the Chinese medicine ZiBu PiYin recipe on the hippocampus in a rat model of diabetes-associated cognitive decline: a proteomic analysis. Diabetologia 2011; 54:1888-99. [PMID: 21509442 DOI: 10.1007/s00125-011-2147-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 03/21/2011] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Increasing evidence suggests that diabetes is associated with an enhanced risk of cognitive decline. The precise mechanisms underlying diabetes-associated cognitive decline (DACD) remain unclear. Here we investigated the molecular changes associated with DACD using a comparative proteomics study of hippocampus in a rat model of type 2 diabetes. In addition, we tested the effects of the Chinese medicine ZiBu PiYin recipe (ZBPYR) on DACD. METHODS The hippocampus was dissected from control, diabetic and diabetic rats treated with ZBPYR (DM/ZBPYR). Soluble proteins were separated using fluorescence-based difference gel electrophoresis. Protein spots were visualised with fluorescent dyes and spot density was compared between each pair of groups. Proteins of interest were identified using mass spectrometry. Proteins of specific interest were also tested by western blot and real-time PCR analysis. RESULTS We found 13 spots that were altered between control and diabetes groups, and 12 spots that were changed between diabetes and DM/ZBPYR groups. The identities of nine proteins were determined by mass spectrometry. The identified proteins were largely involved in energy metabolism, cytoskeleton regulation and oxidative stress. The protein alterations observed in the diabetes group were ameliorated to varying degrees following ZBPYR treatment. CONCLUSIONS/INTERPRETATION The protein changes identified in hippocampus from a rat model of type 2 diabetes suggest that specific cellular alterations contribute to DACD. The Chinese medicine ZBPYR was found to affect multiple targets and partially repaired the original cellular balance. This study may provide important insights into the molecular events underlying DACD and allow the identification of novel therapeutic targets.
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Affiliation(s)
- X Shi
- The Second Affiliated Hospital, Dalian Medical University, Dalian, Liaoning Province 116023, China
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215
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Yoon JS, Mughal MR, Mattson MP. Energy restriction negates NMDA receptor antagonist efficacy in ischemic stroke. Neuromolecular Med 2011; 13:175-8. [PMID: 21660587 DOI: 10.1007/s12017-011-8145-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 04/15/2011] [Indexed: 02/07/2023]
Abstract
Preclinical evaluation of drugs for neurological disorders is usually performed on overfed rodents, without consideration of how metabolic state might affect drug efficacy. Using a widely employed mouse model of focal ischemic stroke, we found that that the NMDA receptor antagonist dizocilpine (MK-801) reduces brain damage and improves functional outcome in mice on the usual ad libitum diet, but exhibits little or no therapeutic efficacy in mice maintained on an energy-restricted diet. Thus, NMDA receptor activation plays a central role in the mechanism by which a high dietary energy intake exacerbates ischemic brain injury. These findings suggest that inclusion of subjects with a wide range of energy intakes in clinical trials for stroke may mask a drug benefit in the overfed/obese subpopulation of subjects.
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Affiliation(s)
- Jeong Seon Yoon
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD, USA
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216
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Texel SJ, Mattson MP. Impaired adaptive cellular responses to oxidative stress and the pathogenesis of Alzheimer's disease. Antioxid Redox Signal 2011; 14:1519-34. [PMID: 20849373 PMCID: PMC3061199 DOI: 10.1089/ars.2010.3569] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
As is generally true with other age-related diseases, Alzheimer's disease (AD) involves oxidative damage to cellular components in the affected tissue, in this case the brain. The causes and consequences of oxidative stress in neurons in AD are not fully understood, but considerable evidence points to important roles for accumulation of amyloid β-peptide upstream of oxidative stress and perturbed cellular Ca(2+) homeostasis and energy metabolism downstream of oxidative stress. The identification of mutations in the β-amyloid precursor protein and presenilin-1 as causes of some cases of early onset inherited AD, and the development of cell culture and animal models based on these mutations has greatly enhanced our understanding of the AD process, and has greatly expanded opportunities for preclinical testing of potential therapeutic interventions. In this regard, and of particular interest to us, is the elucidation of adaptive cellular stress response pathways (ACSRP) that can counteract multiple steps in the AD neurodegenerative cascades, thereby limiting oxidative damage and preserving cognitive function. ACSRP can be activated by factors ranging from exercise and dietary energy restriction, to drugs and phytochemicals. In this article we provide an overview of oxidative stress and AD, with a focus on ACSRP and their potential for preventing and treating AD.
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Affiliation(s)
- Sarah J Texel
- Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, USA
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217
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Onksen JL, Brown EJ, Blendy JA. Selective deletion of a cell cycle checkpoint kinase (ATR) reduces neurogenesis and alters responses in rodent models of behavioral affect. Neuropsychopharmacology 2011; 36:960-9. [PMID: 21248719 PMCID: PMC3077265 DOI: 10.1038/npp.2010.234] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hippocampal function has been implicated in mood and anxiety disorders, as well as in the response to antidepressant (AD) treatment. However, the significance of new neurons in the therapeutic mechanism of ADs remains unclear. In this study, the proliferation of new neurons was inhibited through conditional deletion of ataxia telangeictasia-mutated and rad-3 related (ATR), a cell cycle checkpoint kinase, and cellular and behavioral outcomes following AD exposure were evaluated. ATR was conditionally deleted by microinjecting a Cre recombinase-expressing virus into the hippocampus of floxed-ATR mice. Behavioral assessment in multiple rodent models of affective state revealed anxiolytic-like behavior in the elevated zero maze, marble burying test, and novelty-induced hypophagia (NIH) test. The efficacy of chronic desipramine (DMI) treatment was evaluated in the NIH test, as this paradigm is thought to be sensitive to increases in neurogenesis by chronic AD exposure. Chronic exposure to DMI reduced hyponeophagia in the NIH test in control mice, whereas DMI had no behavioral effect in ATR-deleted mice. Although DMI did not alter cell proliferation in either group, it did produce a robust increase in dendritic spine density in control mice, indicative of enhanced neuronal plasticity. This effect of DMI on spine density was severely attenuated following ATR deletion. These findings demonstrate that reductions in basal neurogenesis produce an anxiolytic phenotype and reduce AD efficacy in behaviors requiring chronic exposure. Furthermore, attenuated capacity for synaptic remodeling may underlie these behaviors. ATR deletion may serve as a valuable model to study the various proposed roles of newborn neurons in the hippocampus.
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Affiliation(s)
- Jennifer L Onksen
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Eric J Brown
- Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Julie A Blendy
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA,Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. Tel: +215 898 0730, Fax: +215 573 2041, E-mail:
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218
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Stranahan AM. Physiological variability in brain-derived neurotrophic factor expression predicts dendritic spine density in the mouse dentate gyrus. Neurosci Lett 2011; 495:60-2. [PMID: 21420469 DOI: 10.1016/j.neulet.2011.03.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 03/11/2011] [Accepted: 03/11/2011] [Indexed: 11/17/2022]
Abstract
Dendritic spines are the predominant sites of excitatory neurotransmission in the adult brain, and brain-derived neurotrophic factor (BDNF) is a well-characterized determinant of dendritic spine number and morphology. The relationship between BDNF expression and dendritic spine number is particularly evident in the hippocampus, where environmental conditions that enhance hippocampal BDNF levels also promote local increases in dendritic spine density. However, the relationship between physiological variability in hippocampal BDNF expression and spine number has yet to be assessed. To determine whether natural variability in BDNF expression is associated with hippocampal dendritic spine number, correlations between BDNF protein levels and dendritic spine density among Golgi-impregnated neurons in the hippocampal dentate gyrus and CA1 subfields were assessed in adult male C57Bl/6J mice. In the dentate gyrus, but not in the apical oblique dendrites of CA1 pyramidal cells, BDNF protein expression was significantly correlated with dendritic spine density. This observation suggests that there may be a subregionally specific relationship between hippocampal BDNF expression and the density of spines.
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Affiliation(s)
- Alexis M Stranahan
- Physiology Department, Georgia Health Sciences University, 1120 15th St., rm CA3145, Augusta, GA 30912, United States.
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219
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Reagan LP. Diabetes as a chronic metabolic stressor: causes, consequences and clinical complications. Exp Neurol 2011; 233:68-78. [PMID: 21320489 DOI: 10.1016/j.expneurol.2011.02.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 01/04/2011] [Accepted: 02/06/2011] [Indexed: 12/30/2022]
Abstract
Diabetes mellitus is an endocrine disorder resulting from inadequate insulin release and/or reduced insulin sensitivity. The complications of diabetes are well characterized in peripheral tissues, but there is a growing appreciation that the complications of diabetes extend to the central nervous system (CNS). One of the potential neurological complications of diabetes is cognitive deficits. Interestingly, the structural, electrophysiological, neurochemical and anatomical underpinnings responsible for cognitive deficits in diabetes are strikingly similar to those observed in animals subjected to chronic stress, as well as in patients with stress-related psychiatric illnesses such as major depressive disorder. Since diabetes is a chronic metabolic stressor, this has led to the suggestion that common mechanistic mediators are responsible for neuroplasticity deficits in both diabetes and depression. Moreover, these common mechanistic mediators may be responsible for the increase in the risk of depressive illness in diabetes patients. In view of these observations, the aims of this review are (1) to describe the neuroplasticity deficits observed in diabetic rodents and patients; (2) to summarize the similarities in the clinical and preclinical studies of depression and diabetes; and (3) to highlight the diabetes-induced neuroplasticity deficits in those brain regions that have been implicated as important pathological centers in depressive illness, namely, the hippocampus, the amygdala and the prefrontal cortex.
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Affiliation(s)
- Lawrence P Reagan
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, USA.
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220
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Stranahan AM, Mattson MP. Bidirectional metabolic regulation of neurocognitive function. Neurobiol Learn Mem 2011; 96:507-16. [PMID: 21236352 DOI: 10.1016/j.nlm.2011.01.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 01/04/2011] [Indexed: 12/16/2022]
Abstract
The efficiency of somatic energy metabolism is correlated with cognitive change over the lifespan. This relationship is bidirectional, with improved overall fitness associated with enhanced synaptic function and neuroprotection, and synaptic endangerment occurring in the context of impaired energy metabolism. In this review, we discuss recent advancements in the fields of exercise, dietary energy intake and diabetes, as they relate to neuronal function in the hippocampus. Because hippocampal neurons have energy requirements that are relatively higher than those of other brain regions, they are uniquely poised to benefit from exercise, and to be harmed by diabetes. We view exercise and dietary energy restriction as being associated with enhanced hippocampal plasticity at one end of a continuum, with obesity and diabetes accompanied by cognitive impairment at the other end of the continuum. Understanding the mechanisms for this continuum may yield novel therapeutic targets for the prevention and treatment of cognitive decline following aging, disease, or injury.
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Affiliation(s)
- Alexis M Stranahan
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
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221
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Stranahan AM, Arumugam TV, Mattson MP. Lowering corticosterone levels reinstates hippocampal brain-derived neurotropic factor and Trkb expression without influencing deficits in hypothalamic brain-derived neurotropic factor expression in leptin receptor-deficient mice. Neuroendocrinology 2011; 93:58-64. [PMID: 21160171 PMCID: PMC3066242 DOI: 10.1159/000322808] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 11/10/2010] [Indexed: 01/07/2023]
Abstract
BACKGROUND/AIMS Changes in the glucocorticoid milieu contribute to alterations in neurotropic factor expression across multiple brain regions. Insulin-resistant diabetes is often accompanied by dysregulation of adrenal steroid production in humans and animal models. Leptin receptor-deficient mice (db/db) show reduced expression of brain-derived neurotropic factor (BDNF) in the hippocampus and increases in circulating corticosterone levels, but the extent to which elevated corticosterone levels mediate deficits in BDNF expression has not been determined. METHODS Using in situ hybridization, we measured the expression of BDNF, its receptor TrkB, and neurotropin-3 (NT-3) in the hippocampus and hypothalamus of db/db mice and wild-type controls following adrenalectomy and low-dose corticosterone replacement (ADX+CORT) or sham operation. RESULTS Lowering corticosterone levels restored BDNF and TrkB expression in the hippocampus of db/db mice. However, deficits in hypothalamic BDNF expression were not reversed following ADX+CORT. There was no effect of genotype or adrenalectomy on NT-3 expression in any brain region examined. CONCLUSION Leptin receptor-deficient mice exhibit reduced BDNF expression in the hippocampus and hypothalamus. In the db/db mouse hippocampus, suppression of BDNF occurs in a glucocorticoid-dependent fashion, while hypothalamic BDNF expression is reduced via glucocorticoid-independent mechanisms. Region-specific signals therefore play a role in the interaction between corticosteroids and neurotropic factor expression.
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Affiliation(s)
- Alexis M Stranahan
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
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222
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Del Arco A, Segovia G, de Blas M, Garrido P, Acuña-Castroviejo D, Pamplona R, Mora F. Prefrontal cortex, caloric restriction and stress during aging: Studies on dopamine and acetylcholine release, BDNF and working memory. Behav Brain Res 2011; 216:136-45. [DOI: 10.1016/j.bbr.2010.07.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 07/15/2010] [Accepted: 07/18/2010] [Indexed: 12/28/2022]
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223
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Disrupted energy metabolism and neuronal circuit dysfunction in cognitive impairment and Alzheimer's disease. Lancet Neurol 2010; 10:187-98. [PMID: 21147038 DOI: 10.1016/s1474-4422(10)70277-5] [Citation(s) in RCA: 393] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Epidemiological, neuropathological, and functional neuroimaging evidence implicates global and regional disruptions in brain metabolism and energetics in the pathogenesis of cognitive impairment. Nerve cell microcircuits are modified by excitatory and inhibitory synaptic activity and neurotrophic factors. Ageing and Alzheimer's disease cause perturbations in cellular energy metabolism, level of excitation or inhibition, and neurotrophic factor release, which overwhelm compensatory mechanisms and result in dysfunction of neuronal microcircuits and brain networks. A prolonged positive energy balance impairs the ability of neurons to adapt to oxidative and metabolic stress. Results from experimental studies in animals show how disruptions caused by chronic positive energy balance, such as diabetes, lead to accelerated cognitive ageing and Alzheimer's disease. Therapeutic interventions to allay cognitive dysfunction that target energy metabolism and adaptive stress responses (such as neurotrophin signalling) have been effective in animal models and in preliminary studies in humans.
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224
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Rich NJ, Van Landingham JW, Figueiroa S, Seth R, Corniola RS, Levenson CW. Chronic caloric restriction reduces tissue damage and improves spatial memory in a rat model of traumatic brain injury. J Neurosci Res 2010; 88:2933-9. [PMID: 20544832 DOI: 10.1002/jnr.22443] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although it has been known for some time that chronic caloric or dietary restriction reduces the risk of neurodegenerative disorders and injury following ischemia, the possible role of chronic restriction in improving outcomes after traumatic brain injury (TBI) has not been previously studied. Therefore, 2-month-old male Sprague-Dawley rats were divided into two dietary groups, an ad libitum fed group (AL) and a caloric-restriction group (CR) that was provided with 70% of the food intake of AL rats (n = 10/group). After 4 months, a weight-drop device (300 g) was used to produce a 2-mm bilateral medial frontal cortex contusion following craniotomy. Additional animals in each dietary group (n = 10) were used as sham-operated controls. The CR diet resulted in body weights that were reduced by 30% compared with AL controls. Not only did CR decrease the size of the cortical lesion after injury, there were marked improvements in spatial memory as measured by Morris water maze that included an increase in the number of animals successfully finding the platform as well as significantly reduced time to finding the hidden platform. Western analysis, used to examine the expression of proteins that play a role in neuronal survival, revealed significant increases in brain-derived neurotrophic factor (BDNF) in the cortical region around the site of injury and in the hippocampus in CR rats after injury. These findings suggest that molecular mechanisms involved in cell survival may play a role in reducing tissue damage and improving cognition after TBI and that these mechanisms can be regulated by dietary interventions.
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Affiliation(s)
- Nicholas J Rich
- Program in Neuroscience and Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306-4300, USA
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225
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Tsutsumi A, Motoshima H, Kondo T, Kawasaki S, Matsumura T, Hanatani S, Igata M, Ishii N, Kinoshita H, Kawashima J, Taketa K, Furukawa N, Tsuruzoe K, Nishikawa T, Araki E. Caloric restriction decreases ER stress in liver and adipose tissue in ob/ob mice. Biochem Biophys Res Commun 2010; 404:339-44. [PMID: 21134353 DOI: 10.1016/j.bbrc.2010.11.120] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 11/26/2010] [Indexed: 11/26/2022]
Abstract
Endoplasmic reticulum (ER) stress plays a crucial role in the development of insulin resistance and diabetes. Although caloric restriction (CR) improves obesity-related disorders, the effects of CR on ER stress in obesity remain unknown. To investigate how CR affects ER stress in obesity, ob/ob mice were assigned to either ad libitum (AL) (ob-AL) or CR (ob-CR) feeding (2 g food/day) for 1-4 weeks. The body weight (BW) of ob-CR mice decreased to the level of lean AL-fed littermates (lean-AL) within 2 weeks. BW of lean-AL and ob-CR mice was less than that of ob-AL mice. The ob-CR mice showed improved glucose tolerance and hepatic insulin action compared with ob-AL mice. Levels of ER stress markers such as phosphorylated PKR-like ER kinase (PERK) and eukaryotic translation initiation factor 2α and the mRNA expression of activating transcription factor 4 were significantly higher in the liver and epididymal fat from ob-AL mice compared with lean-AL mice. CR for 2 and 4 weeks significantly reduced all of these markers to less than 35% and 50%, respectively, of the levels in ob-AL mice. CR also significantly reduced the phosphorylation of insulin receptor substrate (IRS)-1 and c-Jun NH(2)-terminal kinase (JNK) in ob/ob mice. The CR-mediated decrease in PERK phosphorylation was similar to that induced by 4-phenyl butyric acid, which reduces ER stress in vivo. In conclusion, CR reduced ER stress and improved hepatic insulin action by suppressing JNK-mediated IRS-1 serine-phosphorylation in ob/ob mice.
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Affiliation(s)
- Atsuyuki Tsutsumi
- Department of Metabolic Medicine, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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226
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Selective vulnerability of neurons in layer II of the entorhinal cortex during aging and Alzheimer's disease. Neural Plast 2010; 2010:108190. [PMID: 21331296 PMCID: PMC3039218 DOI: 10.1155/2010/108190] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 10/26/2010] [Indexed: 01/04/2023] Open
Abstract
All neurons are not created equal. Certain cell populations in specific brain regions are more susceptible to age-related changes that initiate regional and system-level dysfunction. In this respect, neurons in layer II of the entorhinal cortex are selectively vulnerable in aging and Alzheimer's disease (AD). This paper will cover several hypotheses that attempt to account for age-related alterations among this cell population. We consider whether specific developmental, anatomical, or biochemical features of neurons in layer II of the entorhinal cortex contribute to their particular sensitivity to aging and AD. The entorhinal cortex is a functionally heterogeneous environment, and we will also review data suggesting that, within the entorhinal cortex, there is subregional specificity for molecular alterations that may initiate cognitive decline. Taken together, the existing data point to a regional cascade in which entorhinal cortical alterations directly contribute to downstream changes in its primary afferent region, the hippocampus.
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227
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Lazarov O, Mattson MP, Peterson DA, Pimplikar SW, van Praag H. When neurogenesis encounters aging and disease. Trends Neurosci 2010; 33:569-79. [PMID: 20961627 PMCID: PMC2981641 DOI: 10.1016/j.tins.2010.09.003] [Citation(s) in RCA: 286] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 09/02/2010] [Accepted: 09/13/2010] [Indexed: 11/20/2022]
Abstract
In this review, we consider the evidence that a reduction in neurogenesis underlies aging-related cognitive deficits and impairments in disorders such as Alzheimer's disease (AD). The molecular and cellular alterations associated with impaired neurogenesis in the aging brain are discussed. Dysfunction of presenilin-1, misprocessing of amyloid precursor protein and toxic effects of hyperphosphorylated tau and β-amyloid probably contribute to impaired neurogenesis in AD. Because factors such as exercise, environmental enrichment and dietary energy restriction enhance neurogenesis, and protect against age-related cognitive decline and AD, knowledge of the underlying neurogenic signaling pathways could lead to novel therapeutic strategies for preserving brain function. In addition, manipulation of endogenous neural stem cells and stem cell transplantation, as stand-alone or adjunct treatments, seems promising.
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Affiliation(s)
- Orly Lazarov
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA.
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228
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Influence of physical exercise on neuroimmunological functioning and health: aging and stress. Neurotox Res 2010; 20:69-83. [PMID: 20953749 DOI: 10.1007/s12640-010-9224-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 09/16/2010] [Accepted: 09/21/2010] [Indexed: 12/20/2022]
Abstract
Chronic and acute stress, with associated pathophysiology, are implicated in a variety of disease states, with neuroimmunological dysregulation and inflammation as major hazards to health and functional sufficiency. Psychosocial stress and negative affect are linked to elevations in several inflammatory biomarkers. Immunosenescence, the deterioration of immune competence observed in the aged aspect of the life span, linked to a dramatic rise in morbidity and susceptibility to diseases with fatal outcomes, alters neuroimmunological function and is particularly marked in the neurodegenerative disorders, e.g., Parkinson's disease and diabetes. Physical exercise diminishes inflammation and elevates agents and factors involved in immunomodulatory function. Both the alleviatory effects of life-long physical activity upon multiple cancer forms and the palliative effects of physical activity for individuals afflicted by cancer offer advantages in health intervention. Chronic conditions of stress and affective dysregulation are associated with neuroimmunological insufficiency and inflammation, contributing to health risk and mortality. Physical exercise regimes have induced manifest anti-inflammatory benefits, mediated possibly by brain-derived neurotrophic factor. The epidemic proportions of metabolic disorders, obesity, and diabetes demand attention; several variants of exercise regimes have been found repeatedly to induce both prevention and improvement under both laboratory and clinical conditions. Physical exercise offers a unique non-pharmacologic intervention incorporating multiple activity regimes, e.g., endurance versus resistance exercise that may be adapted to conform to the particular demands of diagnosis, intervention and prognosis inherent to the staging of autoimmune disorders and related conditions.
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229
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Camandola S, Mattson MP. Aberrant subcellular neuronal calcium regulation in aging and Alzheimer's disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:965-73. [PMID: 20950656 DOI: 10.1016/j.bbamcr.2010.10.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 10/01/2010] [Accepted: 10/03/2010] [Indexed: 02/06/2023]
Abstract
In this mini-review/opinion article we describe evidence that multiple cellular and molecular alterations in Alzheimer's disease (AD) pathogenesis involve perturbed cellular calcium regulation, and that alterations in synaptic calcium handling may be early and pivotal events in the disease process. With advancing age neurons encounter increased oxidative stress and impaired energy metabolism, which compromise the function of proteins that control membrane excitability and subcellular calcium dynamics. Altered proteolytic cleavage of the β-amyloid precursor protein (APP) in response to the aging process in combination with genetic and environmental factors results in the production and accumulation of neurotoxic forms of amyloid β-peptide (Aβ). Aβ undergoes a self-aggregation process and concomitantly generates reactive oxygen species that can trigger membrane-associated oxidative stress which, in turn, impairs the functions of ion-motive ATPases and glutamate and glucose transporters thereby rendering neurons vulnerable to excitotoxicity and apoptosis. Mutations in presenilin-1 that cause early-onset AD increase Aβ production, but also result in an abnormal increase in the size of endoplasmic reticulum calcium stores. Some of the events in the neurodegenerative cascade can be counteracted in animal models by manipulations that stabilize neuronal calcium homeostasis including dietary energy restriction, agonists of glucagon-like peptide 1 receptors and drugs that activate mitochondrial potassium channels. Emerging knowledge of the actions of calcium upstream and downstream of Aβ provides opportunities to develop novel preventative and therapeutic interventions for AD. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Affiliation(s)
- Simonetta Camandola
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD, USA
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230
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Cerqueira FM, Kowaltowski AJ. Commonly adopted caloric restriction protocols often involve malnutrition. Ageing Res Rev 2010; 9:424-30. [PMID: 20493280 DOI: 10.1016/j.arr.2010.05.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 05/10/2010] [Accepted: 05/10/2010] [Indexed: 02/08/2023]
Abstract
Undernutrition without malnutrition is an intervention that enhances laboratory animal life span, and is widely studied to uncover factors limiting longevity. In a search of the literature over a course of four years, we found that most protocols currently adopted as caloric restriction do not meet micronutrient standards set by the National Research Council for laboratory rats and mice. We provide evidence that the most commonly adopted caloric restriction protocol, a 40% restriction of the AIN-93 diet without vitamin or mineral supplementation, leads to malnutrition in both mice and rats. Furthermore, others and we find that every other day feeding, another dietary intervention often referred to as caloric restriction, does not limit the total amount of calories consumed. Altogether, we propose that the term "caloric restriction" should be used specifically to describe diets that decrease calorie intake but not micronutrient availability, and that protocols adopted should be described in detail in order to allow for comparisons and better understanding of the effects of these diets.
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231
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Muller AP, Gnoatto J, Moreira JD, Zimmer ER, Haas CB, Lulhier F, Perry ML, Souza DO, Torres-Aleman I, Portela LV. Exercise increases insulin signaling in the hippocampus: Physiological effects and pharmacological impact of intracerebroventricular insulin administration in mice. Hippocampus 2010; 21:1082-92. [DOI: 10.1002/hipo.20822] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2010] [Indexed: 01/05/2023]
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232
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A calorie-restricted diet decreases brain iron accumulation and preserves motor performance in old rhesus monkeys. J Neurosci 2010; 30:7940-7. [PMID: 20534842 DOI: 10.1523/jneurosci.0835-10.2010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Caloric restriction (CR) reduces the pathological effects of aging and extends the lifespan in many species, including nonhuman primates, although the effect on the brain is less well characterized. We used two common indicators of aging, motor performance speed and brain iron deposition measured in vivo using MRI, to determine the potential effect of CR on elderly rhesus macaques eating restricted (n = 24; 13 males, 11 females) and standard diets (n = 17; 8 males, 9 females). Both the CR and control monkeys showed age-related increases in iron concentrations in globus pallidus (GP) and substantia nigra (SN), although the CR group had significantly less iron deposition in the GP, SN, red nucleus, and temporal cortex. A diet x age interaction revealed that CR modified age-related brain changes, evidenced as attenuation in the rate of iron accumulation in basal ganglia and parietal, temporal, and perirhinal cortex. Additionally, control monkeys had significantly slower fine motor performance on the Movement Assessment Panel, which was negatively correlated with iron accumulation in left SN and parietal lobe, although CR animals did not show this relationship. Our observations suggest that the CR-induced benefit of reduced iron deposition and preserved motor function may indicate neural protection similar to effects described previously in aging rodent and primate species.
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233
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Sharma AN, Elased KM, Garrett TL, Lucot JB. Neurobehavioral deficits in db/db diabetic mice. Physiol Behav 2010; 101:381-8. [PMID: 20637218 DOI: 10.1016/j.physbeh.2010.07.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 07/07/2010] [Accepted: 07/08/2010] [Indexed: 01/02/2023]
Abstract
Recent clinical studies indicate neurobehavioral disturbances in type-2 diabetics. However, there is paucity of preclinical research to support this concept. The validity of db/db mouse as an animal model to study type-2 diabetes and related complications is known. The present study was designed to investigate comprehensively the db/db mouse behavior as preclinical evidence of type-2 diabetes related major neurobehavioral complications. We tested juvenile (5-6weeks) and adult (10-11weeks) db/db mice for behavioral depression in forced swim test (FST), psychosis-like symptoms using pre-pulse inhibition (PPI) test, anxiety behavior employing elevated plus maze (EPM) test, locomotor behavior and thigmotaxis using open field test and working memory deficits in Y-maze test. Both juvenile and adult group db/db mice displayed behavioral despair with increased immobility time in FST. There was an age-dependent progression of psychosis-like symptoms with disrupted PPI in adult db/db mice. In the EPM test, db/db mice were less anxious as observed by increased percent open arms time and entries. They were also hypo-locomotive as evident by a decrease in their basic and fine movements. There was no impairment of working memory in the Y-maze test in db/db mice. This is the first report of depression, psychosis-like symptoms and anxiolytic behavior of db/db mouse strain. It is tempting to speculate that this mouse strain can serve as useful preclinical model to study type-2 diabetes related neurobehavioral complications.
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Affiliation(s)
- Ajaykumar N Sharma
- Wright State University, Boonshoft School of Medicine, Department of Pharmacology and Toxicology, Dayton, OH 45435, USA
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234
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Schroeder JE, Richardson JC, Virley DJ. Dietary manipulation and caloric restriction in the development of mouse models relevant to neurological diseases. Biochim Biophys Acta Mol Basis Dis 2010; 1802:840-6. [PMID: 20472058 DOI: 10.1016/j.bbadis.2010.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 04/07/2010] [Accepted: 04/22/2010] [Indexed: 01/24/2023]
Abstract
Manipulation of diet such as increasing the level of fat or inducing insulin resistance has been shown to exacerbate the pathology in several animal models of neurological disease. Caloric restriction, however, has been demonstrated to extend the life span of many organisms. Reduced calorie consumption appears to increase the resistance of neurons to intracellular and extracellular stress and consequently improves the behavioural phenotype in animal models of neurological diseases, such as Alzheimer's disease. We review the evidence from a variety of mouse models that diet is a risk factor that can significantly contribute to the development of neurological diseases.
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Affiliation(s)
- Joern E Schroeder
- Neurosciences CEDD, GlaxoSmithKline, New Frontiers Science Park North, Third Avenue, Harlow, Essex CM195AW, UK
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235
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Xu X, Mughal MR, Scott Hall F, Perona MTG, Pistell PJ, Lathia JD, Chigurupati S, Becker KG, Ladenheim B, Niklason LE, Uhl GR, Cadet JL, Mattson MP. Dietary restriction mitigates cocaine-induced alterations of olfactory bulb cellular plasticity and gene expression, and behavior. J Neurochem 2010; 114:323-34. [PMID: 20456017 DOI: 10.1111/j.1471-4159.2010.06782.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Because the olfactory system plays a major role in food consumption, and because 'food addiction' and associated morbidities have reached epidemic proportions, we tested the hypothesis that dietary energy restriction can modify adverse effects of cocaine on behavior and olfactory cellular and molecular plasticity. Mice maintained on an alternate day fasting (ADF) diet exhibited increased baseline locomotion and increased cocaine-sensitized locomotion during cocaine conditioning, despite no change in cocaine conditioned place preference, compared with mice fed ad libitum. Levels of dopamine and its metabolites in the olfactory bulb (OB) were suppressed in mice on the ADF diet compared with mice on the control diet, independent of acute or chronic cocaine treatment. The expression of several enzymes involved in dopamine metabolism including tyrosine hydroxylase, monoamine oxidases A and B, and catechol-O-methyltransferase were significantly reduced in OBs of mice on the ADF diet. Both acute and chronic administration of cocaine suppressed the production of new OB cells, and this effect of cocaine was attenuated in mice on the ADF diet. Cocaine administration to mice on the control diet resulted in up-regulation of OB genes involved in mitochondrial energy metabolism, synaptic plasticity, cellular stress responses, and calcium- and cAMP-mediated signaling, whereas multiple olfactory receptor genes were down-regulated by cocaine treatment. ADF abolished many of the effects of cocaine on OB gene expression. Our findings reveal that dietary energy intake modifies the neural substrates underlying some of the behavioral and physiological responses to repeated cocaine treatment, and also suggest novel roles for the olfactory system in addiction. The data further suggest that modification of dietary energy intake could provide a novel potential approach to addiction treatments.
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Affiliation(s)
- Xiangru Xu
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA
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236
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Circulating brain-derived neurotrophic factor and indices of metabolic and cardiovascular health: data from the Baltimore Longitudinal Study of Aging. PLoS One 2010; 5:e10099. [PMID: 20404913 PMCID: PMC2852401 DOI: 10.1371/journal.pone.0010099] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 03/10/2010] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Besides its well-established role in nerve cell survival and adaptive plasticity, brain-derived neurotrophic factor (BDNF) is also involved in energy homeostasis and cardiovascular regulation. Although BDNF is present in the systemic circulation, it is unknown whether plasma BDNF correlates with circulating markers of dysregulated metabolism and an adverse cardiovascular profile. METHODOLOGY/PRINCIPAL FINDINGS To determine whether circulating BDNF correlates with indices of metabolic and cardiovascular health, we measured plasma BDNF levels in 496 middle-age and elderly subjects (mean age approximately 70), in the Baltimore Longitudinal Study of Aging. Linear regression analysis revealed that plasma BDNF is associated with risk factors for cardiovascular disease and metabolic syndrome, regardless of age. In females, BDNF was positively correlated with BMI, fat mass, diastolic blood pressure, total cholesterol, and LDL-cholesterol, and inversely correlated with folate. In males, BDNF was positively correlated with diastolic blood pressure, triglycerides, free thiiodo-thyronine (FT3), and bioavailable testosterone, and inversely correlated with sex-hormone binding globulin, and adiponectin. CONCLUSION/SIGNIFICANCE Plasma BDNF significantly correlates with multiple risk factors for metabolic syndrome and cardiovascular dysfunction. Whether BDNF contributes to the pathogenesis of these disorders or functions in adaptive responses to cellular stress (as occurs in the brain) remains to be determined.
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237
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Martin B, Ji S, Maudsley S, Mattson MP. "Control" laboratory rodents are metabolically morbid: why it matters. Proc Natl Acad Sci U S A 2010; 107:6127-33. [PMID: 20194732 PMCID: PMC2852022 DOI: 10.1073/pnas.0912955107] [Citation(s) in RCA: 268] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Failure to recognize that many standard control rats and mice used in biomedical research are sedentary, obese, glucose intolerant, and on a trajectory to premature death may confound data interpretation and outcomes of human studies. Fundamental aspects of cellular physiology, vulnerability to oxidative stress, inflammation, and associated diseases are among the many biological processes affected by dietary energy intake and exercise. Although overfed sedentary rodents may be reasonable models for the study of obesity in humans, treatments shown to be efficacious in these animal models may prove ineffective or exhibit novel side effects in active, normal-weight subjects.
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Affiliation(s)
| | - Sunggoan Ji
- Metabolism Unit, Laboratory of Clinical Investigation
| | - Stuart Maudsley
- Receptor Pharmacology Unit, Laboratory of Neurosciences, and
| | - Mark P. Mattson
- Cellular and Molecular Neurosciences Section, Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
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238
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Mattson MP. The impact of dietary energy intake on cognitive aging. Front Aging Neurosci 2010; 2:5. [PMID: 20552045 PMCID: PMC2874403 DOI: 10.3389/neuro.24.005.2010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 01/27/2010] [Indexed: 01/21/2023] Open
Abstract
Rodents that are insulin resistant and obese as the result of genetic factors, overeating and/or a sedentary lifestyle, exhibit cognitive deficits that worsen with advancing age compared to their more svelte counterparts. Data from epidemiological and clinical studies suggest similar adverse effects of excessive dietary energy intake and insulin resistance on cognition in humans. Our findings from studies of animal models suggest that dietary energy restriction can enhance neural plasticity and reduce the vulnerability of the brain to age-related dysfunction and disease. Dietary energy restriction may exert beneficial effects on the brain by engaging adaptive cellular stress response pathways resulting in the up-regulation of genes that encode proteins that promote neural plasticity and cell survival (e.g., neurotrophic factors, protein chaperones and redox enzymes). Two energy state-sensitive factors that are proving particularly important in regulating energy balance and improving/preserving cognitive function are brain-derived neurotrophic factor and glucagon-like peptide 1. Alternate day calorie restriction, novel insulin-sensitizing and neuroprotective agents, and drugs that activate adaptive stress response pathways, are examples of approaches for preserving cognitive function that show promise in preclinical studies.
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Affiliation(s)
- Mark P. Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research ProgramBaltimore, MD, USA
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239
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Mattson MP. Perspective: Does brown fat protect against diseases of aging? Ageing Res Rev 2010; 9:69-76. [PMID: 19969105 DOI: 10.1016/j.arr.2009.11.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 11/30/2009] [Indexed: 01/01/2023]
Abstract
The most commonly studied laboratory rodents possess a specialized form of fat called brown adipose tissue (BAT) that generates heat to help maintain body temperature in cold environments. In humans, BAT is abundant during embryonic and early postnatal development, but is absent or present in relatively small amounts in adults where it is located in paracervical and supraclavicular regions. BAT cells can 'burn' fatty acid energy substrates to generate heat because they possess large numbers of mitochondria in which oxidative phosphorylation is uncoupled from ATP production as a result of a transmembrane proton leak mediated by uncoupling protein 1 (UCP1). Studies of rodents in which BAT levels are either increased or decreased have revealed a role for BAT in protection against diet-induced obesity. Data suggest that individuals with low levels of BAT are prone to obesity, insulin resistance and cardiovascular disease, whereas those with higher levels of BAT maintain lower body weights and exhibit superior health as they age. BAT levels decrease during aging, and dietary energy restriction increases BAT activity and protects multiple organ systems including the nervous system against age-related dysfunction and degeneration. Future studies in which the effects of specific manipulations of BAT levels and thermogenic activity on disease processes in animal models (diabetes, cardiovascular disease, cancers, neurodegenerative diseases) are determined will establish if and how BAT affects the development and progression of age-related diseases. Data from animal studies suggest that BAT and mitochondrial uncoupling can be targeted for interventions to prevent and treat obesity and age-related diseases. Examples include: diet and lifestyle changes; specific regimens of mild intermittent stress; drugs that stimulate BAT formation and activity; induction of brown adipose cell progenitors in muscle and other tissues; and transplantation of brown adipose cells.
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240
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Das UN. Obesity: genes, brain, gut, and environment. Nutrition 2009; 26:459-73. [PMID: 20022465 DOI: 10.1016/j.nut.2009.09.020] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 09/21/2009] [Accepted: 09/27/2009] [Indexed: 01/04/2023]
Abstract
Obesity, which is assuming alarming proportions, has been attributed to genetic factors, hypothalamic dysfunction, and intestinal gut bacteria and an increase in the consumption of energy-dense food. Obesity predisposes to the development of type 2 diabetes mellitus, hypertension, coronary heart disease, and certain forms of cancer. Recent studies have shown that the intestinal bacteria in obese humans and mice differ from those in lean that could trigger a low-grade systemic inflammation. Consumption of a calorie-dense diet that initiates and perpetuates obesity could be due to failure of homeostatic mechanisms that regulate appetite, food consumption, and energy balance. Hypothalamic factors that regulate energy needs of the body, control appetite and satiety, and gut bacteria that participate in food digestion play a critical role in the onset of obesity. Incretins, cholecystokinin, brain-derived neurotrophic factor, leptin, long-chain fatty acid coenzyme A, endocannabinoids and vagal neurotransmitter acetylcholine play a role in the regulation of energy intake, glucose homeostasis, insulin secretion, and pathobiology of obesity and type 2 diabetes mellitus. Thus, there is a cross-talk among the gut, liver, pancreas, adipose tissue, and hypothalamus. Based on these evidences, it is clear that management of obesity needs a multifactorial approach.
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241
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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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242
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Pedersen BK, Pedersen M, Krabbe KS, Bruunsgaard H, Matthews VB, Febbraio MA. Role of exercise-induced brain-derived neurotrophic factor production in the regulation of energy homeostasis in mammals. Exp Physiol 2009; 94:1153-60. [PMID: 19748969 DOI: 10.1113/expphysiol.2009.048561] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has been shown to regulate neuronal development and plasticity and plays a role in learning and memory. Moreover, it is well established that BDNF plays a role in the hypothalamic pathway that controls body weight and energy homeostasis. Recent evidence identifies BDNF as a player not only in central metabolism, but also in regulating energy metabolism in peripheral organs. Low levels of BDNF are found in patients with neurodegenerative diseases, including Alzheimer's disease and major depression. In addition, BDNF levels are low in obesity and independently so in patients with type 2 diabetes. Brain-derived neurotrophic factor is expressed in non-neurogenic tissues, including skeletal muscle, and exercise increases BDNF levels not only in the brain and in plasma, but in skeletal muscle as well. Brain-derived neurotrophic factor mRNA and protein expression was increased in muscle cells that were electrically stimulated, and BDNF increased phosphorylation of AMP-activated protein kinase (AMPK) and acetyl coenzyme A carboxylase-beta (ACCbeta) and enhanced fatty oxidation both in vitro and ex vivo. These data identify BDNF as a contraction-inducible protein in skeletal muscle that is capable of enhancing lipid oxidation in skeletal muscle via activation of AMPK. Thus, BDNF appears to play a role both in neurobiology and in central as well as peripheral metabolism. The finding of low BDNF levels both in neurodegenerative diseases and in type 2 diabetes may explain the clustering of these diseases. Brain-derived neurotrophic factor is likely to mediate some of the beneficial effects of exercise with regard to protection against dementia and type 2 diabetes.
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Affiliation(s)
- Bente K Pedersen
- Centre of Inflammation and Metabolism, Rigshospitalet-Section 7641, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
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Mattson MP. Roles of the lipid peroxidation product 4-hydroxynonenal in obesity, the metabolic syndrome, and associated vascular and neurodegenerative disorders. Exp Gerontol 2009; 44:625-33. [PMID: 19622391 DOI: 10.1016/j.exger.2009.07.003] [Citation(s) in RCA: 387] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 07/07/2009] [Accepted: 07/14/2009] [Indexed: 11/29/2022]
Abstract
A rising tide of obesity and type 2 diabetes has resulted from the development of technologies that have made inexpensive high calorie foods readily available and exercise unnecessary for many people. Obesity and the metabolic syndrome (insulin resistance, visceral adiposity and dyslipidemia) wreak havoc on cells throughout the body thereby promoting cardiovascular and kidney disease, and degenerative diseases of the brain and body. Obesity and insulin resistance promote disease by increasing oxidative damage to proteins, lipids and DNA as the result of a combination of increased free radical production and an impaired ability of cells to detoxify the radicals and repair damaged molecules. By covalently modifying membrane-associated proteins, the membrane lipid peroxidation product 4-hydroxynonenal (HNE) may play particularly sinister roles in the metabolic syndrome and associated disease processes. HNE can damage pancreatic beta cells and can impair the ability of muscle and liver cells to respond to insulin. HNE may promote atherosclerosis by modifying lipoproteins and can cause cardiac cell damage by impairing metabolic enzymes. An adverse role for HNE in the brain in obesity and the metabolic syndrome is suggested by studies showing that HNE levels are increased in brain cells with aging and Alzheimer's disease. HNE can cause the dysfunction and degeneration of neurons by modifying membrane-associated glucose and glutamate transporters, ion-motive ATPases, enzymes involved in amyloid metabolism, and cytoskeletal proteins. Exercise and dietary energy restriction reduce HNE production and may also increase cellular systems for HNE detoxification including glutathione and oxidoreductases. The recent development of low molecular weight molecules that scavenge HNE suggests that HNE can be targeted in the design of drugs for the treatment of obesity, the metabolic syndrome, and associated disorders.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, USA.
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