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Braunstein PW, Horovitz DJ, Hampton AM, Hollis F, Newman LA, Enos RT, McQuail JA. Daily fluctuations in blood glucose with normal aging are inversely related to hippocampal synaptic mitochondrial proteins. AGING BRAIN 2024; 5:100116. [PMID: 38596458 PMCID: PMC11002859 DOI: 10.1016/j.nbas.2024.100116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 03/29/2024] [Accepted: 03/30/2024] [Indexed: 04/11/2024] Open
Abstract
Defective brain glucose utilization is a hallmark of Alzheimer's disease (AD) while Type II diabetes and elevated blood glucose escalate the risk for AD in later life. Isolating contributions of normal aging from coincident metabolic or brain diseases could lead to refined approaches to manage specific health risks and optimize treatments targeted to susceptible older individuals. We evaluated metabolic, neuroendocrine, and neurobiological differences between young adult (6 months) and aged (24 months) male rats. Compared to young adults, blood glucose was significantly greater in aged rats at the start of the dark phase of the day but not during the light phase. When challenged with physical restraint, a potent stressor, aged rats effected no change in blood glucose whereas blood glucose increased in young adults. Tissues were evaluated for markers of oxidative phosphorylation (OXPHOS), neuronal glucose transport, and synapses. Outright differences in protein levels between age groups were not evident, but circadian blood glucose was inversely related to OXPHOS proteins in hippocampal synaptosomes, independent of age. The neuronal glucose transporter, GLUT3, was positively associated with circadian blood glucose in young adults whereas aged rats tended to show the opposite trend. Our data demonstrate aging increases daily fluctuations in blood glucose and, at the level of individual differences, negatively associates with proteins related to synaptic OXPHOS. Our findings imply that glucose dyshomeostasis may exacerbate metabolic aspects of synaptic dysfunction that contribute to risk for age-related brain disorders.
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Affiliation(s)
- Paul W. Braunstein
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - David J. Horovitz
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | | | - Fiona Hollis
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Lori A. Newman
- Department of Psychological Science, Vassar College, Poughkeepsie, NY, USA
| | - Reilly T. Enos
- Department of Pathology, Microbiology, and Immunology, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Joseph A. McQuail
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
- Department of Neuroscience, University of Florida, Gainesville, FL, USA
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2
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Li F, Wang Y, Wang X, Zhao Y, Xie F, Qian LJ. Dynamic effects of chronic unpredictable mild stress on the hippocampal transcriptome in rats. Mol Med Rep 2022; 25:110. [PMID: 35119083 PMCID: PMC8845063 DOI: 10.3892/mmr.2022.12626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/17/2022] [Indexed: 11/06/2022] Open
Abstract
Stress causes extensive changes in hippocampal genomic expression, leading to changes in hippocampal structure and function. The dynamic changes in hippocampal gene expression caused by stress of different durations are still unknown. mRNA sequencing was used to analyze the hippocampal transcriptome of rats subjected to chronic unpredictable mild stress (CUMS) of different durations. Compared with the control, 501, 442 and 235 differentially expressed genes (DEGs) were detected in the hippocampus of rats subjected to CUMS for 3 days and 2 and 6 weeks, respectively. Gene Ontology (GO) analysis was used to determine the potential mechanism underlying the dynamic harmful effects of stress on the hippocampus; Certain GO terms of the down‑regulated DEGs in CUMS (3 days) rats were also found in the up‑regulated DEGs in CUMS (6 weeks) rats. These results showed opposing regulation patterns of DEGs between CUMS at 3 days and 6 weeks, which suggested a functional change from adaptation to damage in during the early and late stages of chronic stress. GO analysis for upregulated genes in rats subjected to CUMS for 3 days and 2 weeks suggested significant changes in 'extracellular matrix' and 'wound healing'. Upregulated genes in rats subjected to CUMS for 2 weeks were involved in changes associated with visual function. GO analysis of DEGs in rats subjected to CUMS for 6 weeks revealed increased expression of genes associated with 'apoptotic process' and 'aging' and decreased expression of those associated with inhibition of cell proliferation and cell structure. These results suggest that the early and middle stages of chronic stress primarily promote adaptive regulation and damage repair in the organism, while the late stage of chronic stress leads to damage in the hippocampus.
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Affiliation(s)
- Feng Li
- Department of Military Cognitive and Stress Medicine, Beijing Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100039, P.R. China
| | - Ying Wang
- Department of Military Cognitive and Stress Medicine, Beijing Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100039, P.R. China
| | - Xue Wang
- Department of Military Cognitive and Stress Medicine, Beijing Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100039, P.R. China
| | - Yun Zhao
- Department of Military Cognitive and Stress Medicine, Beijing Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100039, P.R. China
| | - Fang Xie
- Department of Military Cognitive and Stress Medicine, Beijing Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100039, P.R. China
| | - Ling-Jia Qian
- Department of Military Cognitive and Stress Medicine, Beijing Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100039, P.R. China
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3
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Herman JP. The neuroendocrinology of stress: Glucocorticoid signaling mechanisms. Psychoneuroendocrinology 2022; 137:105641. [PMID: 34954409 DOI: 10.1016/j.psyneuen.2021.105641] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 01/13/2023]
Abstract
Glucocorticoid signaling plays major roles in energy homeostasis and adaptation to adversity, and dysregulation of this process is linked to systemic and psychological pathology. Over the last several decades, new work has challenged many of the long-standing assumptions regarding regulation of glucocorticoid secretion and glucocorticoid signaling mechanisms, revealing an exquisite complexity that accompanies the important and perhaps global role of these hormones in physiological and psychological regulation. New findings have included discovery of membrane signaling, direct neural control of the adrenal, a role for pulsatile glucocorticoid release in glucocorticoid receptor signaling, marked sex differences in brain glucocorticoid biology, and salutary as well as deleterious roles for glucocorticoids in long- and short-term adaptations to stress. This review covers some of the major lessons learned in the area of mechanisms of glucocorticoid signaling, and discusses how these may inform the field moving forward.
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Affiliation(s)
- James P Herman
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH 45267, USA; Department of Neurology and Rehabilitation Medicine, University of Cincinnati, Cincinnati, OH 45267, USA; Cincinnati Veterans Administration Medical Center, USA
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4
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Jackson MG, Lightman SL, Gilmour G, Marston H, Robinson ESJ. Evidence for deficits in behavioural and physiological responses in aged mice relevant to the psychiatric symptom of apathy. Brain Neurosci Adv 2021; 5:23982128211015110. [PMID: 34104800 PMCID: PMC8161852 DOI: 10.1177/23982128211015110] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/13/2021] [Indexed: 11/30/2022] Open
Abstract
Apathy is widely reported in patients with neurological disorders or post viral infection but is also seen in otherwise-healthy aged individuals. This study investigated whether aged male mice express behavioural and physiological changes relevant to an apathy phenotype. Using measures of motivation to work for reward, we found deficits in the progressive ratio task related to rate of responding. In an effort-related decision-making task, aged mice were less willing to exert effort for high value reward. Aged mice exhibited reduced reward sensitivity but also lower measures of anxiety in the novelty supressed feeding test and an attenuated response to restraint stress with lower corticosterone and reduced paraventricular nucleus c-fos activation. This profile of affective changes did not align with those observed in models of depression but suggested emotional blunting. In a test of cognition (novel object recognition), aged mice showed no impairments, but activity was lower in a measure of exploration in a novel environment. Together, these data suggest aged mice show changes across the domains of motivated behaviour, reward sensitivity and emotional reactivity and may be a suitable model for the pre-clinical study of the psychiatric symptom of apathy.
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Affiliation(s)
- Megan G Jackson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Stafford L Lightman
- Bristol Medical School: Translational Health Sciences, University of Bristol, Bristol, UK
| | | | | | - Emma S J Robinson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
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5
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Stucker S, De Angelis J, Kusumbe AP. Heterogeneity and Dynamics of Vasculature in the Endocrine System During Aging and Disease. Front Physiol 2021; 12:624928. [PMID: 33767633 PMCID: PMC7987104 DOI: 10.3389/fphys.2021.624928] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 02/09/2021] [Indexed: 12/11/2022] Open
Abstract
The endocrine system consists of several highly vascularized glands that produce and secrete hormones to maintain body homeostasis and regulate a range of bodily functions and processes, including growth, metabolism and development. The dense and highly vascularized capillary network functions as the main transport system for hormones and regulatory factors to enable efficient endocrine function. The specialized capillary types provide the microenvironments to support stem and progenitor cells, by regulating their survival, maintenance and differentiation. Moreover, the vasculature interacts with endocrine cells supporting their endocrine function. However, the structure and niche function of vasculature in endocrine tissues remain poorly understood. Aging and endocrine disorders are associated with vascular perturbations. Understanding the cellular and molecular cues driving the disease, and age-related vascular perturbations hold potential to manage or even treat endocrine disorders and comorbidities associated with aging. This review aims to describe the structure and niche functions of the vasculature in various endocrine glands and define the vascular changes in aging and endocrine disorders.
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Affiliation(s)
| | | | - Anjali P. Kusumbe
- Tissue and Tumor Microenvironments Group, Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, United Kingdom
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McQuail JA, Dunn AR, Stern Y, Barnes CA, Kempermann G, Rapp PR, Kaczorowski CC, Foster TC. Cognitive Reserve in Model Systems for Mechanistic Discovery: The Importance of Longitudinal Studies. Front Aging Neurosci 2021; 12:607685. [PMID: 33551788 PMCID: PMC7859530 DOI: 10.3389/fnagi.2020.607685] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 12/30/2020] [Indexed: 12/14/2022] Open
Abstract
The goal of this review article is to provide a resource for longitudinal studies, using animal models, directed at understanding and modifying the relationship between cognition and brain structure and function throughout life. We propose that forthcoming longitudinal studies will build upon a wealth of knowledge gleaned from prior cross-sectional designs to identify early predictors of variability in cognitive function during aging, and characterize fundamental neurobiological mechanisms that underlie the vulnerability to, and the trajectory of, cognitive decline. Finally, we present examples of biological measures that may differentiate mechanisms of the cognitive reserve at the molecular, cellular, and network level.
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Affiliation(s)
- Joseph A. McQuail
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Amy R. Dunn
- The Jackson Laboratory, Bar Harbor, ME, United States
| | - Yaakov Stern
- Cognitive Neuroscience Division, Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, United States
| | - Carol A. Barnes
- Departments of Psychology and Neuroscience, University of Arizona, Tucson, AZ, United States
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, United States
| | - Gerd Kempermann
- CRTD—Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
- German Center for Neurodegenerative Diseases (DZNE), Helmholtz Association of German Research Centers (HZ), Dresden, Germany
| | - Peter R. Rapp
- Laboratory of Behavioral Neuroscience, Neurocognitive Aging Section, National Institute on Aging, Baltimore, MD, United States
| | | | - Thomas C. Foster
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, United States
- Genetics and Genomics Program, University of Florida, Gainesville, FL, United States
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7
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Aged rats with different performances at environmental enrichment onset display different modulation of habituation and aversive memory. Neurobiol Learn Mem 2019; 161:83-91. [PMID: 30951838 DOI: 10.1016/j.nlm.2019.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/20/2019] [Accepted: 04/01/2019] [Indexed: 12/22/2022]
Abstract
A wide agreement exists that environmental enrichment (EE) is most beneficial if introduced early in life, but numerous studies reported that also aged animals remain responsive. As age-related memory and cognition impairments are not uniform, an open question is whether EE might exert different effects in animals with different age-related deficits. A 12-week EE protocol was applied to late adult rats pretested for habituation and aversive memory. Animals were classified as low (LP) and high (HP) performers according to percent exploration change in Open Field test (OF) and as impaired (I) and not impaired (NI) according to latency in Step-through Passive Avoidance test (PA). Standard housing (SH) animals pretested by OF and PA, and naïve (non-pretested) EE and SH rats were used as controls. In comparison to pretest, after the housing protocol, EE LP ameliorated while EE HP and both SH HP and LP worsened their habituation pattern. The positive influence of EE on LP was probably due to the more active interaction with and the faster adaptation to surroundings promoted by continuous, multiple stimuli provided during the enriched housing. Regarding HP, EE did not boost the basal behavior, which likely represented the maximum achievable for that age, and the post housing exploration change dropped, as in SH animals, because of the retesting. After EE, a significant percentage of NI animals became I and a significant percentage of I animals became NI. The changes evidenced in the NI group likely depended on EE-related reduction of anxiety and the consequent more efficient coping with fearful situations. This hypothesis was strengthened by the observation that naïve EE animals were almost all I. Pretested EE I rats were not influenced by the rearing condition: their behavior was comparable to SH animals' behavior and determined by retesting. In conclusion, these results demonstrated that, when applied to aging rats, EE produces different effects based on pre-housing cognitive performances. The issue needs further analyses, but the observation that not all animals are able to take advantage of EE to the same extent suggests the opportunity to design individually tailored approaches to optimize their efficacy and minimize possible unwanted consequences.
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8
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Perez SD, Molinaro CA, Tan L, ThyagaRajan S, Lorton D, Bellinger DL. Sympathetic neurotransmission in spleens from aging Brown-Norway rats subjected to reduced sympathetic tone. J Neuroimmunol 2018; 324:1-15. [PMID: 30195094 DOI: 10.1016/j.jneuroim.2018.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 11/17/2022]
Abstract
Senescence of innate and adaptive responses and low-grade inflammation (inflammaging) hallmarks normal aging, which increases vulnerability to infectious diseases, autoimmunity and cancer. In normal aging, sympathetic dysregulation contributes to the dysregulation of innate and adaptive immunity and inflammaging. Sympathetic innervation of immune cells in secondary immune organs regulates immune responses. Previously in Fischer 344 (F344) rats, we reported an age-related increase in sympathetic tone and sympathetic dysfunction in beta-adrenergic receptor (AR) signaling of splenic lymphocytes that contributes to immune senescence, although the responsible mechanisms remains unexplored. In this study, we extend our previous findings using the much longer-lived Brown-Norway (BN) rats, whose behavior and immune response profile differ strikingly from F344 rats. Here, we investigated whether increased sympathetic nerve activity (SNA) in the aging spleen contributes to age-related sympathetic neuropathy and altered neurotransmission in splenic lymphocytes in BN rats. Fifteen-month male BN rats received 0, 0.5 or 1.5 μg/kg/day rilmenidine intraperitoneally for 90 days to lower sympathetic tone. Untreated young and age-matched rats controlled for effects of age. We found that elevated SNA in the aging BN rat spleen does not contribute significantly to sympathetic neuropathy or the aging-induced impairment of canonical β-AR signal transduction. Despite the rilmenidine-induced increase in β-AR expression, splenocyte c-AMP production was comparable with age-matched controls, thus dampening nerve activity had no effect on receptor coupling to adenylate cyclase. Understanding how aging affects neuroimmune regulation in healthy aging rodent models may eventually lead to strategies that improve health in aging populations vulnerable to immunosenescence and low-grade systemic inflammation.
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Affiliation(s)
- Samuel D Perez
- Department of Biology, Washington Adventist University, MD, Virginia 20912, USA.
| | - Christine A Molinaro
- Department of Human Anatomy and Pathology, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
| | - Laren Tan
- Department of Pulmonary and Critical Care, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
| | - Srinivasan ThyagaRajan
- Integrative Medicine Laboratory, Department of Biotechnology, SRM University, Kattankulathur 603203, India.
| | - Dianne Lorton
- College of Arts and Sciences, Kent State University, Summa Health System, Akron, OH 44304, USA..
| | - Denise L Bellinger
- Department of Human Anatomy and Pathology, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.
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9
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McQuail JA, Krause EG, Setlow B, Scheuer DA, Bizon JL. Stress-induced corticosterone secretion covaries with working memory in aging. Neurobiol Aging 2018; 71:156-160. [PMID: 30144648 DOI: 10.1016/j.neurobiolaging.2018.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/05/2018] [Accepted: 07/24/2018] [Indexed: 12/21/2022]
Abstract
A substantial literature details the relationship between age-related changes to the hypothalamic-pituitary-adrenal axis and deterioration of mnemonic functions that depend on the hippocampus. The relationship between adrenocortical status and other forms of memory that depend on the prefrontal cortex is less well understood in the context of advanced age. Here, we characterized performance of young adult and aged F344 rats on a prefrontal cortex-dependent working memory task and subsequently measured corticosterone (CORT) levels over the diurnal cycle and during exposure to an acute stressor. Our analyses revealed that aged rats with better working memory mounted a greater CORT response during acute stress exposure than either young adults or age-matched rats with impaired working memory. We also observed that age-related elevation of basal CORT levels is not associated with working memory performance. Jointly, these data reveal that the hypothalamic-pituitary-adrenal axis-mediated response to acute stress is positively associated with working memory in aging.
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Affiliation(s)
- Joseph A McQuail
- Department of Neuroscience, University of Florida, Gainesville, FL, USA.
| | - Eric G Krause
- Department of Pharmacodynamics, University of Florida, Gainesville, FL, USA
| | - Barry Setlow
- Department of Neuroscience, University of Florida, Gainesville, FL, USA; Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - Deborah A Scheuer
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, USA
| | - Jennifer L Bizon
- Department of Neuroscience, University of Florida, Gainesville, FL, USA; Department of Psychiatry, University of Florida, Gainesville, FL, USA.
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10
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Pietrelli A, Di Nardo M, Masucci A, Brusco A, Basso N, Matkovic L. Lifelong Aerobic Exercise Reduces the Stress Response in Rats. Neuroscience 2018; 376:94-107. [DOI: 10.1016/j.neuroscience.2018.02.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 02/08/2018] [Accepted: 02/11/2018] [Indexed: 02/07/2023]
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11
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Neurobiological effects of repeated radiofrequency exposures in male senescent rats. Biogerontology 2016; 17:841-857. [DOI: 10.1007/s10522-016-9654-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/23/2016] [Indexed: 11/28/2022]
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12
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Herman JP, McKlveen JM, Ghosal S, Kopp B, Wulsin A, Makinson R, Scheimann J, Myers B. Regulation of the Hypothalamic-Pituitary-Adrenocortical Stress Response. Compr Physiol 2016; 6:603-21. [PMID: 27065163 DOI: 10.1002/cphy.c150015] [Citation(s) in RCA: 966] [Impact Index Per Article: 120.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The hypothalamo-pituitary-adrenocortical (HPA) axis is required for stress adaptation. Activation of the HPA axis causes secretion of glucocorticoids, which act on multiple organ systems to redirect energy resources to meet real or anticipated demand. The HPA stress response is driven primarily by neural mechanisms, invoking corticotrophin releasing hormone (CRH) release from hypothalamic paraventricular nucleus (PVN) neurons. Pathways activating CRH release are stressor dependent: reactive responses to homeostatic disruption frequently involve direct noradrenergic or peptidergic drive of PVN neurons by sensory relays, whereas anticipatory responses use oligosynaptic pathways originating in upstream limbic structures. Anticipatory responses are driven largely by disinhibition, mediated by trans-synaptic silencing of tonic PVN inhibition via GABAergic neurons in the amygdala. Stress responses are inhibited by negative feedback mechanisms, whereby glucocorticoids act to diminish drive (brainstem) and promote transsynaptic inhibition by limbic structures (e.g., hippocampus). Glucocorticoids also act at the PVN to rapidly inhibit CRH neuronal activity via membrane glucocorticoid receptors. Chronic stress-induced activation of the HPA axis takes many forms (chronic basal hypersecretion, sensitized stress responses, and even adrenal exhaustion), with manifestation dependent upon factors such as stressor chronicity, intensity, frequency, and modality. Neural mechanisms driving chronic stress responses can be distinct from those controlling acute reactions, including recruitment of novel limbic, hypothalamic, and brainstem circuits. Importantly, an individual's response to acute or chronic stress is determined by numerous factors, including genetics, early life experience, environmental conditions, sex, and age. The context in which stressors occur will determine whether an individual's acute or chronic stress responses are adaptive or maladaptive (pathological).
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Affiliation(s)
- James P Herman
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Jessica M McKlveen
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Sriparna Ghosal
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Brittany Kopp
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Aynara Wulsin
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Ryan Makinson
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Jessie Scheimann
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
| | - Brent Myers
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, USA
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Suen WW, Prow NA, Setoh YX, Hall RA, Bielefeldt-Ohmann H. End-point disease investigation for virus strains of intermediate virulence as illustrated by flavivirus infections. J Gen Virol 2015; 97:366-377. [PMID: 26614392 DOI: 10.1099/jgv.0.000356] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Viruses of intermediate virulence are defined as isolates causing an intermediate morbidity/mortality rate in a specific animal model system, involving specific host and inoculation parameters (e.g. dose and route). Therefore, variable disease phenotype may exist between animals that develop severe disease or die and those that are asymptomatic or survive after infection with these isolates. There may also be variability amongst animals within each of these subsets. Such potential variability may confound the use of time-point sacrifice experiments to investigate pathogenesis of this subset of virus strains, as uniformity in disease outcome is a fundamental assumption for time-course sacrifice experiments. In the current study, we examined the disease phenotype, neuropathology, neural infection and glial cell activity in moribund/dead and surviving Swiss white (CD-1) mice after intraperitoneal infection with various Australian flaviviruses, including West Nile virus (WNV) strains of intermediate virulence (WNVNSW2011 and WNVNSW2012), and highly virulent Murray Valley encephalitis virus (MVEV) isolates. We identified notable intragroup variation in the end-point disease in mice infected with either WNVNSW strain, but to a lesser extent in mice infected with MVEV strains. The variable outcomes associated with WNVNSW infection suggest that pathogenesis investigations using time-point sacrifice of WNVNSW-infected mice may not be the best approach, as the assumption of uniformity in outcomes is violated. Our study has therefore highlighted a previously unacknowledged challenge to investigating pathogenesis of virus isolates of intermediate virulence. We have also set a precedent for routine examination of the disease phenotype in moribund/dead and surviving mice during survival challenge experiments.
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Affiliation(s)
- Willy W Suen
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
| | - Natalie A Prow
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Yin X Setoh
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Roy A Hall
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Helle Bielefeldt-Ohmann
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, Queensland 4072, Australia.,School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
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14
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15
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Samson RD, Venkatesh A, Patel DH, Lipa P, Barnes CA. Enhanced performance of aged rats in contingency degradation and instrumental extinction tasks. Behav Neurosci 2014; 128:122-33. [PMID: 24773433 DOI: 10.1037/a0035986] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Normal aging in rats affects behavioral performance on a variety of associative learning tasks under Pavlovian conditions. There is little information, however, on whether aging also impacts performance of instrumental tasks. Young (9-12 months) and aged (24-27 months) Fisher 344 rats were trained to press distinct levers associated with either maltodextrin or sucrose. The rats in both age groups increased their lever press frequency at a similar rate, suggesting that the initial acquisition of this instrumental task is not affected by aging. Using a contingency degradation procedure, we then addressed whether aged rats could adapt their behavior to changes in action-outcome contingencies. We found that young and aged rats do adapt, but that a different schedule of reinforcement is necessary to optimize performance in each age group. Finally, we also addressed whether aged rats can extinguish a lever press action as well as young rats, using 2 40-min extinction sessions on consecutive days. While extinction profiles were similar in young and aged rats on the first day of training, aged rats were faster to extinguish their lever presses on the second day, in spite of their performance levels being similar at the beginning of the session. Together these data support the finding that acquisition of instrumental lever press behaviors is preserved in aged rats and suggest that they have a different threshold for switching strategies in response to changes in action-outcome associations. This pattern of result implies that age-related changes in the brain are heterogeneous and widespread across structures.
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Affiliation(s)
| | - Anu Venkatesh
- Evelyn F. McKnight Brain Institute, University of Arizona
| | - Dhara H Patel
- Evelyn F. McKnight Brain Institute, University of Arizona
| | - Peter Lipa
- Evelyn F. McKnight Brain Institute, University of Arizona
| | - Carol A Barnes
- Evelyn F. McKnight Brain Institute, University of Arizona
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Buechel HM, Popovic J, Staggs K, Anderson KL, Thibault O, Blalock EM. Aged rats are hypo-responsive to acute restraint: implications for psychosocial stress in aging. Front Aging Neurosci 2014; 6:13. [PMID: 24575039 PMCID: PMC3921565 DOI: 10.3389/fnagi.2014.00013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/20/2014] [Indexed: 11/13/2022] Open
Abstract
Cognitive processes associated with prefrontal cortex and hippocampus decline with age and are vulnerable to disruption by stress. The stress/stress hormone/allostatic load hypotheses of brain aging posit that brain aging, at least in part, is the manifestation of life-long stress exposure. In addition, as humans age, there is a profound increase in the incidence of new onset stressors, many of which are psychosocial (e.g., loss of job, death of spouse, social isolation), and aged humans are well-understood to be more vulnerable to the negative consequences of such new-onset chronic psychosocial stress events. However, the mechanistic underpinnings of this age-related shift in chronic psychosocial stress response, or the initial acute phase of that chronic response, have been less well-studied. Here, we separated young (3 month) and aged (21 month) male F344 rats into control and acute restraint (an animal model of psychosocial stress) groups (n = 9–12/group). We then assessed hippocampus-associated behavioral, electrophysiological, and transcriptional outcomes, as well as blood glucocorticoid and sleep architecture changes. Aged rats showed characteristic water maze, deep sleep, transcriptome, and synaptic sensitivity changes compared to young. Young and aged rats showed similar levels of distress during the 3 h restraint, as well as highly significant increases in blood glucocorticoid levels 21 h after restraint. However, young, but not aged, animals responded to stress exposure with water maze deficits, loss of deep sleep and hyperthermia. These results demonstrate that aged subjects are hypo-responsive to new-onset acute psychosocial stress, which may have negative consequences for long-term stress adaptation and suggest that age itself may act as a stressor occluding the influence of new onset stressors.
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Affiliation(s)
- Heather M Buechel
- Blalock Laboratory, Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky Lexington, KY, USA
| | - Jelena Popovic
- Blalock Laboratory, Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky Lexington, KY, USA
| | - Kendra Staggs
- Blalock Laboratory, Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky Lexington, KY, USA
| | - Katie L Anderson
- Thibault Laboratory, Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky Lexington, KY, USA
| | - Olivier Thibault
- Thibault Laboratory, Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky Lexington, KY, USA
| | - Eric M Blalock
- Blalock Laboratory, Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky Lexington, KY, USA
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Chugh G, Asghar M, Patki G, Bohat R, Jafri F, Allam F, Dao AT, Mowrey C, Alkadhi K, Salim S. A high-salt diet further impairs age-associated declines in cognitive, behavioral, and cardiovascular functions in male Fischer brown Norway rats. J Nutr 2013; 143:1406-13. [PMID: 23864508 PMCID: PMC3743272 DOI: 10.3945/jn.113.177980] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/02/2013] [Accepted: 06/20/2013] [Indexed: 01/11/2023] Open
Abstract
Aging-associated declines in cognitive, emotional, and cardiovascular function are well known. Environmental stress triggers critical changes in the brain, further compromising cardiovascular and behavioral health during aging. Excessive dietary salt intake is one such stressor. Here, we tested the effect of high salt (HS) on anxiety, learning-memory function, and blood pressure (BP) in male Fischer brown Norway (FBN) rats. Adult (A; 2 mo) and old (O; 20 mo) male rats were fed normal-salt (NS; 0.4% NaCl) or HS (8% NaCl) diets for 4 wk after being implanted with telemeter probes for conscious BP measurement. Thereafter, tests to assess anxiety-like behavior and learning-memory were conducted. The rats were then killed, and samples of plasma, urine, and brain tissue were collected. We found that systolic BP was higher in O-NS (117 ± 1.2 mm Hg) than in A-NS (105 ± 0.8 mm Hg) rats (P < 0.05). Furthermore, BP was higher in O-HS (124 ± 1.4 mm Hg) than in O-NS (117 ± 1.2 mm Hg) rats (P < 0.05). Moreover, anxiety-like behavior (light-dark and open-field tests) was not different between A-NS and O-NS rats but was greater in O-HS rats than in A-NS, O-NS, or A-HS rats (P < 0.05). Short-term memory (radial arm water maze test) was similar in A-NS and O-NS rats but was significantly impaired in O-HS rats compared with A-NS, O-NS, or A-HS rats (P < 0.05). Furthermore, oxidative stress variables (in plasma, urine, and brain) as well as corticosterone (plasma) were greater in O-HS rats when compared with A-NS, O-NS, or A-HS rats (P < 0.05). The antioxidant enzyme glyoxalase-1 expression was selectively reduced in the hippocampus and amygdala of O-HS rats compared with A-NS, O-NS, or A-HS rats (P < 0.05), whereas other antioxidant enzymes, glutathione reductase 1, manganese superoxide dismutase (SOD), and Cu/Zn SOD remained unchanged. We suggest that salt-sensitive hypertension and behavioral derangement are associated with a redox imbalance in the brain of aged FBN rats.
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Affiliation(s)
- Gaurav Chugh
- Department of Pharmacological and Pharmaceutical Sciences, and
- Heart and Kidney Institute, University of Houston, Houston, TX
| | - Mohammad Asghar
- Department of Pharmacological and Pharmaceutical Sciences, and
- Heart and Kidney Institute, University of Houston, Houston, TX
| | - Gaurav Patki
- Department of Pharmacological and Pharmaceutical Sciences, and
| | - Ritu Bohat
- Department of Pharmacological and Pharmaceutical Sciences, and
| | - Faizan Jafri
- Department of Pharmacological and Pharmaceutical Sciences, and
| | - Farida Allam
- Department of Pharmacological and Pharmaceutical Sciences, and
| | - An T. Dao
- Department of Pharmacological and Pharmaceutical Sciences, and
| | | | - Karim Alkadhi
- Department of Pharmacological and Pharmaceutical Sciences, and
| | - Samina Salim
- Department of Pharmacological and Pharmaceutical Sciences, and
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18
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Chaloner A, Greenwood-Van Meerveld B. Genetic diversity contributes to abnormalities in pain behaviors between young and old rats. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1-10. [PMID: 22095259 PMCID: PMC3543734 DOI: 10.1007/s11357-011-9323-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 10/05/2011] [Indexed: 05/31/2023]
Abstract
Aging has profound yet unpredictable effects on pain perception and incidence of anxiety disorders. However, the mechanisms underlying age-related pathologies are confounded by contradictory observations in rodent models. Therefore, the goal of our study was to test the hypothesis that genetic variability contributes to age-related pain behaviors and susceptibility to anxiety. To address this hypothesis, we examined pain and anxiety-like behavior in young or old Brown Norway (BN), Fisher 344, and BN/F344 (F1), three rat strains used in studies to evaluate the effect of aging. Mechanosensitive thresholds were assessed using the Von Frey assay, and visceral pain sensitivity was measured via the visceromotor response to colorectal distension. Anxiety-like behavior and exploration was quantified in the elevated plus maze. In the BN strain, old rats exhibited increased mechanosensitive thresholds compared to young rats; however, age did not affect visceral sensitivity in this strain. In F344-BN rats, the number of abdominal contractions induced by the highest colonic distension pressure was significantly lower in old rats. However, following colonic sensitization, a difference was no longer apparent. In the F-344 strain, visceral hypersensitivity following afferent sensitization was evident in young rats at all distension pressures but was not observed in older animals at 20 mmHg. Aging significantly reduced maze exploration across all strains. Our data demonstrate that age- and strain-related alterations exist in pain behavior and highlight the effects of aging on exploratory behavior. These findings suggest that strain differences contribute to the controversial data on the effects of aging on pain perception.
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Affiliation(s)
- A. Chaloner
- />Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104 USA
| | - Beverley Greenwood-Van Meerveld
- />VA Medical Center, Oklahoma Center for Neuroscience, Department of Physiology – University of Oklahoma Health Sciences Center, Maildrop 151 G, 921 NE 13th St., Oklahoma City, OK 73104 USA
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19
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Garrido P, De Blas M, Giné E, Santos Á, Mora F. Aging impairs the control of prefrontal cortex on the release of corticosterone in response to stress and on memory consolidation. Neurobiol Aging 2012; 33:827.e1-9. [DOI: 10.1016/j.neurobiolaging.2011.06.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 02/28/2011] [Accepted: 06/17/2011] [Indexed: 12/27/2022]
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Garrido P, de Blas M, Del Arco A, Segovia G, Mora F. Aging increases basal but not stress-induced levels of corticosterone in the brain of the awake rat. Neurobiol Aging 2012; 33:375-82. [DOI: 10.1016/j.neurobiolaging.2010.02.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 02/08/2010] [Accepted: 02/19/2010] [Indexed: 11/12/2022]
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Pietrelli A, Lopez-Costa J, Goñi R, Brusco A, Basso N. Aerobic exercise prevents age-dependent cognitive decline and reduces anxiety-related behaviors in middle-aged and old rats. Neuroscience 2011; 202:252-66. [PMID: 22183054 DOI: 10.1016/j.neuroscience.2011.11.054] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 11/23/2011] [Accepted: 11/27/2011] [Indexed: 01/24/2023]
Abstract
Recent research involving human and animals has shown that aerobic exercise of moderate intensity produces the greatest benefit on brain health and behavior. In this study we investigated the effects on cognitive function and anxiety-related behavior in rats at different ages of aerobic exercise, performed regularly throughout life. We designed an aerobic training program with the treadmill running following the basic principles of human training, and assuming that rats have the same physiological adaptations. The intensity was gradually adjusted to the fitness level and age, and maintained at 60-70% of maximum oxygen consumption (max.VO(2)). In middle age (8 months) and old age (18 months), we studied the cognitive response with the radial maze (RM), and anxiety-related behaviors with the open field (OF) and the elevated plus maze (EPM). Aerobically trained (AT) rats had a higher cognitive performance measured in the RM, showing that exercise had a cumulative and amplifier effect on memory and learning. The analysis of age and exercise revealed that the effects of aerobic exercise were modulated by age. Middle-aged AT rats were the most successful animals; however, the old AT rats met the criteria more often than the middle-aged sedentary controls (SC), indicating that exercise could reverse the negative effects of sedentary life, partially restore the cognitive function, and protect against the deleterious effects of aging. The results in the OF and EPM showed a significant decrease in key indicators of anxiety, revealing that age affected most of the analyzed variables, and that exercise had a prominent anxiolytic effect, particularly strong in old age. In conclusion, our results indicated that regular and chronic aerobic exercise has time and dose-dependent, neuroprotective and restorative effects on physiological brain aging, and reduces anxiety-related behaviors.
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Affiliation(s)
- A Pietrelli
- School of Health Sciences, Department of Basic Sciences Research, University of Business and Social Sciences (UCES), Buenos Aires, Argentina.
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22
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Garrido P. Aging and stress: past hypotheses, present approaches and perspectives. Aging Dis 2011; 2:80-99. [PMID: 22396868 PMCID: PMC3295041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 08/05/2010] [Accepted: 08/05/2010] [Indexed: 05/31/2023] Open
Abstract
Brain aging has been suggested to be conditioned by an excessive glucocortioid secretion leading to damages on brain areas involved not only in cognitive and emotional processes but also in the control of the activity of the hypothalamic-pituitary adrenal axis. This review describes some of the hypothesis that try to explain the relation between the dysregulation of the stress response and brain aging, focusing on corticosterone but also on neurotransmission in the hippocampus, the prefrontal cortex and the amygdala. Moreover, different molecular factors can account for an enhanced vulnerability of the aged brain to stress exposure, specially for resilience. Among them, good candidates could be those mechanisms determining the levels of corticosterone in the brain, several molecules downstream glucocorticoid receptor activation (ie: heat shock proteins, BAG-1) or even the epigenetic programming of the HPA axis in early stages. In conclusion, genetic and environmental factors (early life stress, chronic stress during adulthood) can produce an enhanced vulnerability and a reduced resilience of the brain to subsequent stress exposures or to metabolic challenges leading, in turn, to an unsuccessful aging of the brain. However, results obtained with the use of the environmental enrichment model in animals, added to several results in humans also described in this review suggest that positive environmental factors (cognitive-demanding tasks or physical exercise) can help to maintain neuronal plasticity during aging and to protect the brain against the damaging effects of stress exposure.
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Affiliation(s)
- Pedro Garrido
- Correspondence should be addressed to: Dr. Pedro Garrido, Department of Physiology, Faculty of Medicine, Universidad Complutense, Avda Complutense s/n, 28040, SPAIN. E-mail:
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Perez SD, Silva D, Millar AB, Molinaro CA, Carter J, Bassett K, Lorton D, Garcia P, Tan L, Gross J, Lubahn C, Thyagarajan S, Bellinger DL. Sympathetic innervation of the spleen in male Brown Norway rats: a longitudinal aging study. Brain Res 2009; 1302:106-17. [PMID: 19748498 DOI: 10.1016/j.brainres.2009.09.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 09/02/2009] [Accepted: 09/04/2009] [Indexed: 12/27/2022]
Abstract
Aging leads to reduced cellular immunity with consequent increased rates of infectious disease, cancer, and autoimmunity in the elderly. The sympathetic nervous system (SNS) modulates innate and adaptive immunity via innervation of lymphoid organs. In aged Fischer 344 (F344) rats, noradrenergic (NA) nerve density in secondary lymphoid organs declines, which may contribute to immunosenescence with aging. These studies suggest there is SNS involvement in age-induced immune dysregulation. The purpose of this study was to longitudinally characterize age-related change in sympathetic innervation of the spleen and sympathetic activity/tone in male Brown Norway (BN) rats, which live longer and have a strikingly different immune profile than F344 rats, the traditional animal model for aging research. Splenic sympathetic neurotransmission was evaluated between 8 and 32 months of age by assessing (1) NA nerve fiber density, (2) splenic norepinephrine (NE) concentration, and (3) circulating catecholamine levels after decapitation. We report a decline in NA nerve density in splenic white pulp (45%) at 15 months of age compared with 8-month-old (M) rats, which is followed by a much slower rate of decline between 24 and 32 months. Lower splenic NE concentrations between 15 and 32 months of age compared with 8M rats were consistent with morphometric findings. Circulating catecholamine levels after decapitation stress generally dropped with increasing age. These findings suggest there is a sympathetic-to-immune system dysregulation beginning at middle age. Given the unique T-helper-2 bias in BN rats, altered sympathetic-immune communication may be important for understanding the age-related rise in asthma and autoimmunity.
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Affiliation(s)
- Sam D Perez
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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Sex differences in stress-induced hyperthermia in rats: restraint versus confinement. Physiol Behav 2009; 98:416-20. [PMID: 19616565 DOI: 10.1016/j.physbeh.2009.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 07/02/2009] [Accepted: 07/09/2009] [Indexed: 11/22/2022]
Abstract
Studies using restraint to induce psychological stress consistently report the expected hyperthermic response in core body temperature (CBT), but many also report a hypothermic response that precedes the hyperthermia. To understand the conditions that produce hypothermia, and to study sex differences in stress-induced hyperthermia, we measured CBT in male and female rats at 70 and 180 days of age in response to two types of stressors: immobilization through restraint (Plexiglas restrainer) and confinement in a small area (circular wire mesh cylinders that allowed free airflow). Restraint early in the light period induced hypothermia only in 180-day-old males, with no hyperthermia observed during the 30-minute restraint period. Increases in humidity and temperature of the microenvironment due to the larger body weight at this age may contribute to the hypothermia. Hyperthermia during restraint in 70-day-old males was significantly attenuated and delayed in onset compared to the rise in females. All females exhibited a CBT rise of approximately 1.3 degrees C occurring 10-15 min after the onset of restraint. Restraint early in the dark period induced no significant change in CBT in males of either age during immobilization, while females exhibited a small rise of approximately 0.5 degrees C. Confinement early in the light period induced a significant rise of approximately 1.5 degrees C in all groups, with no preceding hypothermia. However, the male response was significantly delayed compared to females. Overall, these results indicate that CBT changes during restraint likely involve both anxiogenic and physiological components, while the marked hyperthermia during confinement is primarily psychological in both sexes.
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Kasckow J, Xiao C, Herman JP. Glial glucocorticoid receptors in aged Fisher 344 (F344) and F344/Brown Norway rats. Exp Gerontol 2009; 44:335-43. [PMID: 19249343 DOI: 10.1016/j.exger.2009.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 02/04/2009] [Accepted: 02/16/2009] [Indexed: 01/15/2023]
Abstract
Glucocorticoid receptors (GR) regulate glial function, and changes in astrocyte gene expression are implicated in age-related pathology. We evaluated changes in astroglial GR expression in two strains of rats--Fisher 344 (F344; 4, 12 and 24 months) and F344/Brown Norway strain (F344/BN; 4, 12 and 30 months). In both strains basal levels of corticosterone were higher in the oldest groups of rats. Age-related increases in GR (+) astrocytes but not the percent of astrocytes expressing GR were observed in the hippocampus CA1 region in F344 rats. Age-related decreases in CA1 GR (+) astrocytes and the percentage of GR (+) astrocytes were observed in the F344/BN strain only. Similar strain-specific changes were observed in the dentate gyrus. In the hypothalamic paraventricular nucleus: (1) F344 rats exhibited significant decreases in the overall number of glial profiles with age, (2) F344/BN rats exhibited decreases in the numbers of GR (+) astrocytes with aging and (3) the proportion of GR (+) astrocytes decreased in older F344/BN, but not F344 rats. Overall, the data demonstrate age- and strain-related alterations in GR astrocytic expression that may explain unique phenotypic differences in brain function observed in both strains.
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Affiliation(s)
- J Kasckow
- VA Pittsburgh Health Care System (116A), Behavioral Health, 7180 Highland Dr. Pittsburgh, PA 15206, USA.
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