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Aldrich JC, Scheinfeld AR, Lee SE, Dusenbery KJ, Mahach KM, Van de Veire BC, Fonken LK, Gaudet AD. Effects of dim light at night in C57BL/6 J mice on recovery after spinal cord injury. Exp Neurol 2024; 375:114725. [PMID: 38365132 PMCID: PMC10981559 DOI: 10.1016/j.expneurol.2024.114725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/09/2024] [Accepted: 02/12/2024] [Indexed: 02/18/2024]
Abstract
Spinal cord injury (SCI) can cause long-lasting locomotor deficits, pain, and mood disorders. Anatomical and functional outcomes are exacerbated by inflammation after SCI, which causes secondary damage. One promising target after SCI is manipulating the circadian system, which optimizes biology and behavior for time of day - including neuroimmune responses and mood-related behaviors. Circadian disruption after SCI is likely worsened by a disruptive hospital environment, which typically includes dim light-at-night (dLAN). Here, we hypothesized that mice subjected to SCI, then placed in dLAN, would exhibit worsened locomotor deficits, pain-like behavior, and anxiety-depressive-like symptoms compared to mice maintained in light days with dark nights (LD). C57BL/6 J mice received sham surgery or moderate T9 contusion SCI, then were placed permanently in LD or dLAN. dLAN after SCI did not worsen locomotor deficits; rather, SCI-dLAN mice showed slight improvement in open-field locomotion at the final timepoint. Although dLAN did not alter SCI-induced heat hyperalgesia, SCI-dLAN mice exhibited an increase in mechanical allodynia at 13 days post-SCI compared to SCI-LD mice. SCI-LD and SCI-dLAN mice had similar outcomes using sucrose preference (depressive-like) and open-field (anxiety-like) tests. At 21 dpo, SCI-dLAN mice had reduced preference for a novel juvenile compared to SCI-LD, implying that dLAN combined with SCI may worsen this mood-related behavior. Finally, lesion size was similar between SCI-LD and SCI-dLAN mice. Therefore, newly placing C57BL/6 J mice in dLAN after SCI had modest effects on locomotor, pain-like, and mood-related behaviors. Future studies should consider whether clinically-relevant circadian disruptors, alone or in combination, could be ameliorated to enhance outcomes after SCI.
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Affiliation(s)
- John C Aldrich
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Ashley R Scheinfeld
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Sydney E Lee
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Kalina J Dusenbery
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Kathryn M Mahach
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Brigid C Van de Veire
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin
| | - Andrew D Gaudet
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin.
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2
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Aldrich JC, Scheinfeld AR, Lee SE, Dusenbery KJ, Mahach KM, Van de Veire BC, Fonken LK, Gaudet AD. Effects of dim light at night in C57BL/6J mice on recovery after spinal cord injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.15.557980. [PMID: 37745393 PMCID: PMC10516041 DOI: 10.1101/2023.09.15.557980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Spinal cord injury (SCI) can cause long-lasting locomotor deficits, pain, and mood disorders. Anatomical and functional outcomes are exacerbated by inflammation after SCI, which causes secondary damage. One promising target after SCI is manipulating the circadian system, which optimizes biology and behavior for time of day - including neuroimmune responses and mood-related behaviors. Circadian disruption after SCI is likely worsened by a disruptive hospital environment, which typically includes dim light-at-night (dLAN). Here, we hypothesized that mice subjected to SCI, then placed in dLAN, would exhibit worsened locomotor deficits, pain-like behavior, and anxiety-depressive-like symptoms compared to mice maintained in light days with dark nights (LD). C57BL/6J mice received sham surgery or moderate T9 contusion SCI, then were placed permanently in LD or dLAN. dLAN after SCI did not worsen locomotor deficits; rather, SCI-dLAN mice showed slight improvement in open-field locomotion at the final timepoint. Although dLAN did not alter SCI-induced heat hyperalgesia, SCI-dLAN mice exhibited an increase in mechanical allodynia at 13 days post-SCI compared to SCI-LD mice. SCI-LD and SCI-dLAN mice had similar outcomes using sucrose preference (depressive-like) and open-field (anxiety-like) tests. At 21 dpo, SCI-dLAN mice had reduced preference for a novel juvenile compared to SCI-LD, implying that dLAN combined with SCI may worsen this mood-related behavior. Finally, lesion size was similar between SCI-LD and SCI-dLAN mice. Therefore, newly placing C57BL/6J mice in dLAN after SCI had modest effects on locomotor, pain-like, and mood-related behaviors. Future studies should consider whether clinically-relevant circadian disruptors, alone or in combination, could be ameliorated to enhance outcomes after SCI.
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Affiliation(s)
- John C Aldrich
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Ashley R Scheinfeld
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Sydney E Lee
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Kalina J Dusenbery
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Kathryn M Mahach
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Brigid C Van de Veire
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin
| | - Andrew D Gaudet
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin
- Department of Neurology, Dell Medical School, The University of Texas at Austin
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3
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Hetman M, Slomnicki L, Hodges E, Ohri SS, Whittemore SR. Role of circadian rhythms in pathogenesis of acute CNS injuries: Insights from experimental studies. Exp Neurol 2022; 353:114080. [DOI: 10.1016/j.expneurol.2022.114080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/28/2022] [Accepted: 04/05/2022] [Indexed: 11/16/2022]
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Slomnicki LP, Wei G, Burke DA, Hodges ER, Myers SA, Yarberry CD, Morehouse JR, Whittemore SR, Saraswat Ohri S, Hetman M. Limited changes in locomotor recovery and unaffected white matter sparing after spinal cord contusion at different times of day. PLoS One 2021; 16:e0249981. [PMID: 34813603 PMCID: PMC8610253 DOI: 10.1371/journal.pone.0249981] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 10/20/2021] [Indexed: 11/18/2022] Open
Abstract
The circadian gene expression rhythmicity drives diurnal oscillations of physiological processes that may determine the injury response. While outcomes of various acute injuries are affected by the time of day at which the original insult occurred, such influences on recovery after spinal cord injury (SCI) are unknown. We report that mice receiving moderate, T9 contusive SCI at ZT0 (zeitgeber time 0, time of lights on) and ZT12 (time of lights off) showed similar hindlimb function recovery in the Basso mouse scale (BMS) over a 6 week post-injury period. In an independent study, no significant differences in BMS were observed after SCI at ZT18 vs. ZT6. However, the ladder walking test revealed modestly improved performance for ZT18 vs. ZT6 mice at week 6 after injury. Consistent with those minor effects on functional recovery, terminal histological analysis revealed no significant differences in white matter sparing at the injury epicenter. Likewise, blood-spinal cord barrier disruption and neuroinflammation appeared similar when analyzed at 1 week post injury at ZT6 or ZT18. Therefore, locomotor recovery after thoracic contusive SCI is not substantively modulated by the time of day at which the neurotrauma occurred.
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Affiliation(s)
- Lukasz P. Slomnicki
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - George Wei
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Darlene A. Burke
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Emily R. Hodges
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Scott A. Myers
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Christine D. Yarberry
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Johnny R. Morehouse
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Scott R. Whittemore
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Anatomical Sciences & Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Sujata Saraswat Ohri
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Michal Hetman
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- Department of Anatomical Sciences & Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
- * E-mail:
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Protective Role of Glutathione in the Hippocampus after Brain Ischemia. Int J Mol Sci 2021; 22:ijms22157765. [PMID: 34360532 PMCID: PMC8345998 DOI: 10.3390/ijms22157765] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 11/16/2022] Open
Abstract
Stroke is a major cause of death worldwide, leading to serious disability. Post-ischemic injury, especially in the cerebral ischemia-prone hippocampus, is a serious problem, as it contributes to vascular dementia. Many studies have shown that in the hippocampus, ischemia/reperfusion induces neuronal death through oxidative stress and neuronal zinc (Zn2+) dyshomeostasis. Glutathione (GSH) plays an important role in protecting neurons against oxidative stress as a major intracellular antioxidant. In addition, the thiol group of GSH can function as a principal Zn2+ chelator for the maintenance of Zn2+ homeostasis in neurons. These lines of evidence suggest that neuronal GSH levels could be a key factor in post-stroke neuronal survival. In neurons, excitatory amino acid carrier 1 (EAAC1) is involved in the influx of cysteine, and intracellular cysteine is the rate-limiting substrate for the synthesis of GSH. Recently, several studies have indicated that cysteine uptake through EAAC1 suppresses ischemia-induced neuronal death via the promotion of hippocampal GSH synthesis in ischemic animal models. In this article, we aimed to review and describe the role of GSH in hippocampal neuroprotection after ischemia/reperfusion, focusing on EAAC1.
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Sominsky L, Dangel T, Malik S, De Luca SN, Singewald N, Spencer SJ. Microglial ablation in rats disrupts the circadian system. FASEB J 2021; 35:e21195. [PMID: 33200466 DOI: 10.1096/fj.202001555rr] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 01/26/2023]
Abstract
Microglia, the key neuroimmune cells of the central nervous system, are best known for their function in defending an individual from pathogens and injury. Recent findings, including our own, suggest microglia also have several immune-independent roles, including in regulating satiety, promoting memory, and modifying pain responses. Many of these microglia-associated functions are affected by circadian rhythmicity, thus, varying substantially depending upon the time of day. To gain further insight into this link, we used a Cx3cr1-Dtr transgenic Wistar rat model to acutely deplete microglia and examined if this could lead to a disruption in diurnal temperature, metabolism, and activity measures. We also examined if differences in the physiological rhythms corresponded with changes in the expression of key circadian rhythm-regulating genes and proteins. Our data show that in the absence of microglia there is a pronounced disruption of diurnal rhythms in several domains consistent with a shift toward the inactive phase, in conjunction with changes in circadian rhythm-regulating genes and proteins. These data suggest microglia are involved in the regulation of circadian rhythms and indicate an exciting potential to manipulate these cells to improve disrupted circadian rhythms such as with shift-work or jet-lag.
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Affiliation(s)
- Luba Sominsky
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Tamara Dangel
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Sajida Malik
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Simone N De Luca
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Sarah J Spencer
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
- ARC Centre of Excellence for Nanoscale Biophotonics, RMIT University, Melbourne, VIC, Australia
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7
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Higashi Y, Aratake T, Shimizu S, Shimizu T, Saito M. [The neuroprotective role of EAAC1 in hippocampal injury following ischemia-reperfusion]. Nihon Yakurigaku Zasshi 2021; 156:21-25. [PMID: 33390475 DOI: 10.1254/fpj.20069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Ischemic stroke is one of the most prevalent brain disorders and the major cause of long-term disability. In particularly, hippocampal injury after ischemia-reperfusion is a serious problem as it contributes to vascular dementia. Many researches have revealed that ischemia-reperfusion causes increase in reactive oxygen species production and disruption of neuronal Zn2+ homeostasis in the hippocampus, which induces hippocampal neuron death. Glutathione (GSH) is present in all mammalian cells and plays a crucial role in neuronal cell defense against oxidative stress. On the other hand, thiol group of GSH chemically chelates Zn2+ and functions as a regulator of neuronal Zn2+ homeostasis. These evidences suggest that neuronal GSH levels could be an important factor affecting neuronal surviving. The synthesis of GSH is largely influenced by intracellular cysteine availability. In neurons, excitatory amino acid carrier type 1 (EAAC1) acts as a cysteine transporter and provides cysteine substrate for GSH synthesis. Recently, several animal studies have revealed that promotion of neuronal GSH synthesis through EAAC1 reduces ischemia-induced hippocampal neuron death. This review aims to describe neuroprotective role of GSH against hippocampal injury following ischemia-reperfusion, focusing on EAAC1.
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Affiliation(s)
| | - Takaaki Aratake
- Department of Pharmacology, Kochi Medical School, Kochi University
| | - Shogo Shimizu
- Department of Pharmacology, Kochi Medical School, Kochi University
| | - Takahiro Shimizu
- Department of Pharmacology, Kochi Medical School, Kochi University
| | - Motoaki Saito
- Department of Pharmacology, Kochi Medical School, Kochi University
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8
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Liu JA, Walton JC, DeVries AC, Nelson RJ. Disruptions of Circadian Rhythms and Thrombolytic Therapy During Ischemic Stroke Intervention. Front Neurosci 2021; 15:675732. [PMID: 34177452 PMCID: PMC8222607 DOI: 10.3389/fnins.2021.675732] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/11/2021] [Indexed: 11/24/2022] Open
Abstract
Several endogenous and exogenous factors interact to influence stroke occurrence, in turn contributing to discernable daily distribution patterns in the frequency and severity of cerebrovascular events. Specifically, strokes that occur during the morning tend to be more severe and are associated with elevated diastolic blood pressure, increased hospital stay, and worse outcomes, including mortality, compared to strokes that occur later in the day. Furthermore, disrupted circadian rhythms are linked to higher risk for stroke and play a role in stroke outcome. In this review, we discuss the interrelation among core clock genes and several factors contributing to ischemic outcomes, sources of disrupted circadian rhythms, the implications of disrupted circadian rhythms in foundational stroke scientific literature, followed by a review of clinical implications. In addition to highlighting the distinct daily pattern of onset, several aspects of physiology including immune response, endothelial/vascular and blood brain barrier function, and fibrinolysis are under circadian clock regulation; disrupted core clock gene expression patterns can adversely affect these physiological processes, leading to a prothrombotic state. Lastly, we discuss how the timing of ischemic onset increases morning resistance to thrombolytic therapy and the risk of hemorrhagic transformation.
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Affiliation(s)
- Jennifer A Liu
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States
| | - James C Walton
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States
| | - A Courtney DeVries
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States.,Department of Medicine, Division of Oncology/Hematology, West Virginia University, Morgantown, WV, United States.,West Virginia University Cancer Institute, West Virginia University, Morgantown, WV, United States
| | - Randy J Nelson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States
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The role of diurnal fluctuations in excitatory amino acid carrier 1 levels in post-ischemic hippocampal Zn 2+ accumulation. Exp Neurol 2020; 336:113538. [PMID: 33253705 DOI: 10.1016/j.expneurol.2020.113538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/04/2020] [Accepted: 11/22/2020] [Indexed: 02/06/2023]
Abstract
Accumulating evidence indicates time-of-day variations in ischemic neuronal injury. Under ischemic conditions, Zn2+ is massively released from hippocampal glutamatergic neurons, and intracellular Zn2+ accumulation results in neuron death. Notably, excitatory amino acid carrier 1 (EAAC1), known as a cysteine transporter, is involved in Zn2+ homeostasis, and its expressions exhibit a diurnal fluctuation. This study aimed to investigate whether time of day of an ischemic insult affects Zn2+ accumulation and neuronal injury and determine whether altered Zn2+ accumulation is modulated by EAAC1 diurnal fluctuation in the hippocampus in a mouse model of ischemic stroke. Mice subjected to transient global ischemia for 40 min at Zeitgeber time 18 (ZT18) (23:00) exhibited reduced Zn2+ accumulation and neuronal death in the hilar region of the hippocampus compared to those at ZT4 (09:00). The EAAC1 protein expression in the hippocampus was increased at ZT18 relative to ZT4. Intracerebroventricular injection of a non-selective excitatory amino acid transporter inhibitor, DL-threo-β-benzyloxyaspartate, or a selective EAAC1 inhibitor, L-aspartic acid β-hydroxamate, increased ischemia-induced Zn2+ accumulation and neuronal death in the hilus at ZT18. These findings suggest that ischemia-induced Zn2+ accumulation displays circadian fluctuations through diurnal variations in EAAC1 expressions and affects susceptibility to ischemic neuronal injury in the hippocampal hilar region.
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Weil ZM, Fonken LK, Walker WH, Bumgarner JR, Liu JA, Melendez-Fernandez OH, Zhang N, DeVries AC, Nelson RJ. Dim light at night exacerbates stroke outcome. Eur J Neurosci 2020; 52:4139-4146. [PMID: 32691462 PMCID: PMC7958865 DOI: 10.1111/ejn.14915] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 07/08/2020] [Indexed: 12/15/2022]
Abstract
Circadian rhythms are endogenous biological cycles that synchronize physiology and behaviour to promote optimal function. These ~24-hr internal rhythms are set to precisely 24 hr daily by exposure to the sun. However, the prevalence of night-time lighting has the potential to dysregulate these biological functions. Hospital patients may be particularly vulnerable to the consequences of light at night because of their compromised physiological state. A mouse model of stroke (middle cerebral artery occlusion; MCAO) was used to test the hypothesis that exposure to dim light at night impairs responses to a major insult. Stroke lesion size was substantially larger among animals housed in dLAN after reperfusion than animals maintained in dark nights. Mice housed in dLAN for three days after the stroke displayed increased post-stroke anxiety-like behaviour. Overall, dLAN amplified pro-inflammatory pathways in the CNS, which may have exacerbated neuronal damage. Our results suggest that exposure to LAN is detrimental to stroke recovery.
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Affiliation(s)
- Zachary M. Weil
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Laura K. Fonken
- Division of Pharmacology and Toxicology, University of Texas, Austin, TX, USA
| | - William H. Walker
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Jacob R. Bumgarner
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Jennifer A. Liu
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
| | - O. Hecmarie Melendez-Fernandez
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Ning Zhang
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
| | - A. Courtney DeVries
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
- Department of Medicine, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Randy J. Nelson
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV, USA
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11
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Differences in Diurnal Variation of Immune Responses in Microglia and Macrophages: Review and Perspectives. Cell Mol Neurobiol 2019; 40:301-309. [PMID: 31549296 DOI: 10.1007/s10571-019-00736-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 09/07/2019] [Indexed: 12/18/2022]
Abstract
Biological rhythms, especially those that last close to 24 h, better known as circadian rhythms, are highly regulated phenomena, maintained throughout evolution in various organisms which allow organisms to predict, prepare for, and adapt to environmental changes. One of these phenomena that exhibit biological rhythms is the immune response to external agents. Immune cells (neutrophils, lymphocytes, macrophages, among others), as well as their mediators such as cytokines and chemokines, undergo variations in tissue and blood concentrations during the day. These rhythms are still being elucidated in microglia, the resident macrophages of the central nervous system, but since these cells share a common origin with peripheral macrophages, they are expected to behave similarly. In this review, we will discuss the possible differences in the responses between peripheral macrophages and microglia, their relationship with the circadian clock, and whether these rhythms can influence therapeutic choices.
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12
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Fonken LK, Bedrosian TA, Zhang N, Weil ZM, DeVries AC, Nelson RJ. Dim light at night impairs recovery from global cerebral ischemia. Exp Neurol 2019; 317:100-109. [PMID: 30822422 DOI: 10.1016/j.expneurol.2019.02.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/12/2018] [Accepted: 02/12/2019] [Indexed: 12/13/2022]
Abstract
Nighttime lighting is one of the great conveniences of modernization; however, there is mounting evidence that inopportune light exposure can disrupt physiological and behavioral functions. Hospital patients may be particularly vulnerable to the consequences of light at night due to their compromised physiological state. Cardiac arrest/cardiopulmonary resuscitation (CA) was used to test the hypothesis in mice that exposure to dim light at night impairs central nervous system (CNS) recovery from a major pathological insult. Mice exposed to dim light at night (5 lx) had higher mortality in the week following cardiac arrest compared to mice housed in dark nights (0 lx). Neuronal damage was significantly greater in surviving mice exposed to dim light at night after CA versus those housed in dark nights. Dim light at night may have elevated neuronal damage by amplifying pro-inflammatory pathways in the CNS; Iba1 immunoreactivity (an indication of microglia activation) and pro-inflammatory cytokine expression were elevated in mice exposed to dim light at night post-CA. Furthermore, selective inhibition of IL-1β or TNFα ameliorated damage in mice exposed to dim light at night. The effects of light at night on CA outcomes were also prevented by using a wavelength of nighttime light that has minimal impact on the endogenous circadian clock, suggesting that replacing broad-spectrum nighttime light with specific circadian-inert wavelengths could be protective. Together, these data indicate that exposure to dim light at night after global cerebral ischemia increases neuroinflammation, in turn exacerbating neurological damage and potential for mortality.
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Affiliation(s)
- Laura K Fonken
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA.
| | - Tracy A Bedrosian
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Ning Zhang
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Zachary M Weil
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - A Courtney DeVries
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Randy J Nelson
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
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Wahul AB, Joshi PC, Kumar A, Chakravarty S. Transient global cerebral ischemia differentially affects cortex, striatum and hippocampus in Bilateral Common Carotid Arterial occlusion (BCCAo) mouse model. J Chem Neuroanat 2018; 92:1-15. [DOI: 10.1016/j.jchemneu.2018.04.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 04/23/2018] [Accepted: 04/23/2018] [Indexed: 12/24/2022]
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14
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Prendergast BJ, Cable EJ, Stevenson TJ, Onishi KG, Zucker I, Kay LM. Circadian Disruption Alters the Effects of Lipopolysaccharide Treatment on Circadian and Ultradian Locomotor Activity and Body Temperature Rhythms of Female Siberian Hamsters. J Biol Rhythms 2016; 30:543-56. [PMID: 26566981 DOI: 10.1177/0748730415609450] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The effect of circadian rhythm (CR) disruption on immune function depends on the method by which CRs are disrupted. Behavioral and thermoregulatory responses induced by lipopolysaccharide (LPS) treatment were assessed in female Siberian hamsters in which circadian locomotor activity (LMA) rhythms were eliminated by exposure to a disruptive phase-shifting protocol (DPS) that sustains arrhythmicity even when hamsters are housed in a light-dark cycle. This noninvasive treatment avoids genome manipulations and neurological damage associated with other models of CR disruption. Circadian rhythmic (RHYTH) and arrhythmic (ARR) hamsters housed in a 16L:8D photocycle were injected with bacterial LPS near the onset of the light (zeitgeber time 1; ZT1) or dark (ZT16) phase. LPS injections at ZT16 and ZT1 elicited febrile responses in both RHYTH and ARR hamsters, but the effect was attenuated in the arrhythmic females. In ZT16, LPS inhibited LMA in the dark phase immediately after injection but not on subsequent nights in both chronotypes; in contrast, LPS at ZT1 elicited more enduring (~4 day) locomotor hypoactivity in ARR than in RHYTH hamsters. Power and period of dark-phase ultradian rhythms (URs) in LMA and Tb were markedly altered by LPS treatment, as was the power in the circadian waveform. Disrupted circadian rhythms in this model system attenuated responses to LPS in a trait- and ZT-specific manner; changes in UR period and power are novel components of the acute-phase response to infection that may affect energy conservation.
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Affiliation(s)
- Brian J Prendergast
- Department of Psychology, University of Chicago, Chicago, Illinois Committee on Neurobiology, University of Chicago, Chicago, Illinois
| | - Erin J Cable
- Department of Psychology, University of Chicago, Chicago, Illinois
| | | | - Kenneth G Onishi
- Department of Psychology, University of Chicago, Chicago, Illinois
| | - Irving Zucker
- Department of Psychology, University of California, Berkeley, California Department of Integrative Biology, University of California, Berkeley, California
| | - Leslie M Kay
- Department of Psychology, University of Chicago, Chicago, Illinois Committee on Neurobiology, University of Chicago, Chicago, Illinois
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15
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Fonken LK, Frank MG, Kitt MM, Barrientos RM, Watkins LR, Maier SF. Microglia inflammatory responses are controlled by an intrinsic circadian clock. Brain Behav Immun 2015; 45:171-9. [PMID: 25433170 PMCID: PMC4386638 DOI: 10.1016/j.bbi.2014.11.009] [Citation(s) in RCA: 193] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 11/04/2014] [Accepted: 11/18/2014] [Indexed: 10/24/2022] Open
Abstract
The circadian system regulates many physiological functions including inflammatory responses. For example, mortality caused by lipopolysaccharide (LPS) injection varies depending on the time of immunostimulation in mammals. The effects of more subtle challenges on the immune system and cellular mechanisms underlying circadian differences in neuroinflammatory responses are not well understood. Here we show that adult male Sprague-Dawley rats injected with a sub-septic dose of LPS during the light phase displayed elevated sickness behaviors and hippocampal cytokine production compared to rats injected during the dark phase. Microglia are the primary central nervous system (CNS) immune cell type and may mediate diurnal differences in sickness response, thus we explored whether microglia demonstrate temporal variations in inflammatory factors. Hippocampal microglia isolated from adult rats rhythmically expressed inflammatory factors and circadian clock genes. Microglia displayed robust rhythms of TNFα, IL1β and IL6 mRNA, with peak cytokine gene expression occurring during the middle of the light phase. Microglia isolated during the light phase were also more reactive to immune stimulation; such that, ex vivo LPS treatment induced an exaggerated cytokine response in light phase-isolated microglia. Treating microglia with corticosterone ex vivo induced expression of the circadian clock gene Per1. However, microglia isolated from adrenalectomized rats maintained temporal differences in clock and inflammatory gene expression. This suggests circadian clock gene expression in microglia is entrained by, but oscillates in the absence of, glucocorticoids. Taken together, these findings demonstrate that microglia possess a circadian clock that influences inflammatory responses. These results indicate time-of-day is an important factor to consider when planning inflammatory interventions such as surgeries or immunotherapies.
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Affiliation(s)
- Laura K Fonken
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309, USA.
| | - Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309, USA
| | - Meagan M Kitt
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309, USA
| | - Ruth M Barrientos
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309, USA
| | - Linda R Watkins
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309, USA
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16
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Prendergast BJ, Cable EJ, Patel PN, Pyter LM, Onishi KG, Stevenson TJ, Ruby NF, Bradley SP. Impaired leukocyte trafficking and skin inflammatory responses in hamsters lacking a functional circadian system. Brain Behav Immun 2013; 32:94-104. [PMID: 23474187 PMCID: PMC3686870 DOI: 10.1016/j.bbi.2013.02.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/20/2013] [Accepted: 02/27/2013] [Indexed: 01/19/2023] Open
Abstract
The immune system is under strong circadian control, and circadian desynchrony is a risk factor for metabolic disorders, inflammatory responses and cancer. Signaling pathways that maintain circadian rhythms (CRs) in immune function in vivo, and the mechanisms by which circadian desynchrony impairs immune function, remain to be fully identified. These experiments tested the hypothesis that the hypothalamic circadian pacemaker in the suprachiasmatic nucleus (SCN) drives CRs in the immune system, using a non-invasive model of SCN circadian arrhythmia. Robust CRs in blood leukocyte trafficking, with a peak during the early light phase (ZT4) and nadir in the early dark phase (ZT18), were absent in arrhythmic hamsters, as were CRs in spleen clock gene (per1, bmal1) expression, indicating that a functional pacemaker in the SCN is required for the generation of CRs in leukocyte trafficking and for driving peripheral clocks in secondary lymphoid organs. Pinealectomy was without effect on CRs in leukocyte trafficking, but abolished CRs in spleen clock gene expression, indicating that nocturnal melatonin secretion is necessary for communicating circadian time information to the spleen. CRs in trafficking of antigen presenting cells (CD11c(+) dendritic cells) in the skin were abolished, and antigen-specific delayed-type hypersensitivity skin inflammatory responses were markedly impaired in arrhythmic hamsters. The SCN drives robust CRs in leukocyte trafficking and lymphoid clock gene expression; the latter of which is not expressed in the absence of melatonin. Robust entrainment of the circadian pacemaker provides a signal critical to diurnal rhythms in immunosurveilliance and optimal memory T-cell dependent immune responses.
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Affiliation(s)
- Brian J. Prendergast
- Department of Psychology, University of Chicago, Chicago, IL 60637,Committee on Neurobiology, University of Chicago, Chicago, IL 60637
| | - Erin J. Cable
- Department of Psychology, University of Chicago, Chicago, IL 60637
| | - Priyesh N. Patel
- Department of Psychology, University of Chicago, Chicago, IL 60637
| | - Leah M. Pyter
- Department of Psychology, University of Chicago, Chicago, IL 60637
| | | | | | - Norman F. Ruby
- Department of Biological Sciences, Stanford University, Palo Alto, CA 94305
| | - Sean P. Bradley
- Department of Psychology, University of Chicago, Chicago, IL 60637
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17
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Manfredini R, Boari B, Salmi R, Fabbian F, Pala M, Tiseo R, Portaluppi F. Twenty-four-hour patterns in occurrence and pathophysiology of acute cardiovascular events and ischemic heart disease. Chronobiol Int 2012; 30:6-16. [PMID: 23002808 DOI: 10.3109/07420528.2012.715843] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The scientific literature clearly establishes the occurrence of cardiovascular (CV) accidents and myocardial ischemic episodes is unevenly distributed during the 24 h. Such temporal patterns result from corresponding temporal variation in pathophysiologic mechanisms and cyclic environmental triggers that elicit the onset of clinical events. Moreover, both the pharmacokinetics and pharmacodynamics of many, though not all, CV medications have been shown to be influenced by the circadian time of their administration, even though further studies are necessary to better clarify the mechanisms of such influence on different drug classes, drug molecules, and pharmaceutical preparations. Twenty-four-hour rhythmic organization of CV functions is such that defense mechanisms against acute events are incapable of providing the same degree of protection during the day and night. Instead, temporal gates of excessive susceptibility exist, particularly in the morning and to a lesser extent evening (in diurnally active persons), to aggressive mechanisms through which overt clinical manifestations may be triggered. When peak levels of critical physiologic variables, such as blood pressure (BP), heart rate (HR), rate pressure product (systolic BP × HR, surrogate measure of myocardial oxygen demand), sympathetic activation, and plasma levels of endogenous vasoconstricting substances, are aligned together at the same circadian time, the risk of acute events becomes significantly elevated such that even relatively minor and usually harmless physical and mental stress and environmental phenomena can precipitate dramatic life-threatening clinical manifestations. Hence, the delivery of CV medications needs to be synchronized in time, i.e., circadian time, in proportion to need as determined by established temporal patterns in risk of CV events, and in a manner that averts or minimizes undesired side effects.
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Affiliation(s)
- Roberto Manfredini
- Section of Clinica Medica, Department of Clinical and Experimental Medicine, University of Ferrara, Via Savonarola 9, Ferrara, Italy
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18
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Kilic U, Yilmaz B, Ugur M, Yüksel A, Reiter RJ, Hermann DM, Kilic E. Evidence that membrane-bound G protein-coupled melatonin receptors MT1 and MT2 are not involved in the neuroprotective effects of melatonin in focal cerebral ischemia. J Pineal Res 2012; 52:228-35. [PMID: 21913972 DOI: 10.1111/j.1600-079x.2011.00932.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Melatonin is synthesized and released by the pineal gland in a circadian rhythm, and many of its peripheral actions are mediated via membrane MT1 and MT2 receptors. Apart from its metabolic functions, melatonin is a potent neuroprotective molecule owing to its antioxidative actions. The roles of MT1 and MT2 in the neuroprotective effects of melatonin and cell signaling after cerebral ischemia remain unknown. With the use of MT1 and MT2 knockout (mt1/2(-/-) ) mice treated with melatonin, we evaluated brain injury, edema formation, inducible nitric oxide synthase (iNOS) activity, and signaling pathways, including CREB, ATF-1, p21, Jun kinase (JNK)1/2, p38 phosphorylation, resulting from ischemia/reperfusion injury. We show that the infarct volume and brain edema do not differ between mt1/2(-/-) and wild-type (WT) animals, but melatonin treatment decreases infarct volume in both groups and brain edema in WT animals after middle cerebral artery occlusion. Notably, melatonin's neuroprotective effect was even more pronounced in mt1/2(-/-) animals compared to that in WT animals. We also demonstrate that melatonin treatment decreased CREB, ATF-1, and p38 phosphorylation in both mt1/2(-/-) and WT mice, while p21 and JNK1/2 were reduced only in melatonin-treated WT animals in the ischemic hemisphere. Furthermore, melatonin treatment lowered iNOS activity only in WT animals. We provide evidence that the absence of MT1 and MT2 has no unfavorable effect on ischemic brain injury. In addition, the neuroprotective effects of melatonin appear to be mediated through a mechanism independent of its membrane receptors. The underlying mechanism(s) should be further studied using selective melatonin receptor agonists and antagonists.
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Affiliation(s)
- Ulkan Kilic
- Department of Medical Biology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
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19
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Vicencio JM, Estrada M, Galvis D, Bravo R, Contreras AE, Rotter D, Szabadkai G, Hill JA, Rothermel BA, Jaimovich E, Lavandero S. Anabolic androgenic steroids and intracellular calcium signaling: a mini review on mechanisms and physiological implications. Mini Rev Med Chem 2011; 11:390-8. [PMID: 21443511 DOI: 10.2174/138955711795445880] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 01/21/2011] [Indexed: 02/05/2023]
Abstract
Increasing evidence suggests that nongenomic effects of testosterone and anabolic androgenic steroids (AAS) operate concertedly with genomic effects. Classically, these responses have been viewed as separate and independent processes, primarily because nongenomic responses are faster and appear to be mediated by membrane androgen receptors, whereas long-term genomic effects are mediated through cytosolic androgen receptors regulating transcriptional activity. Numerous studies have demonstrated increases in intracellular Ca2+ in response to AAS. These Ca2+ mediated responses have been seen in a diversity of cell types, including osteoblasts, platelets, skeletal muscle cells, cardiac myocytes and neurons. The versatility of Ca2+ as a second messenger provides these responses with a vast number of pathophysiological implications. In cardiac cells, testosterone elicits voltage-dependent Ca2+ oscillations and IP3R-mediated Ca2+ release from internal stores, leading to activation of MAPK and mTOR signaling that promotes cardiac hypertrophy. In neurons, depending upon concentration, testosterone can provoke either physiological Ca2+ oscillations, essential for synaptic plasticity, or sustained, pathological Ca2+ transients that lead to neuronal apoptosis. We propose therefore, that Ca2+ acts as an important point of crosstalk between nongenomic and genomic AAS signaling, representing a central regulator that bridges these previously thought to be divergent responses.
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Affiliation(s)
- J M Vicencio
- Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences/Faculty of Medicine, University of Chile, Santiago, Chile
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20
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Portaluppi F, Tiseo R, Smolensky MH, Hermida RC, Ayala DE, Fabbian F. Circadian rhythms and cardiovascular health. Sleep Med Rev 2011; 16:151-66. [PMID: 21641838 DOI: 10.1016/j.smrv.2011.04.003] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/27/2011] [Indexed: 11/30/2022]
Abstract
The functional organization of the cardiovascular system shows clear circadian rhythmicity. These and other circadian rhythms at all levels of organization are orchestrated by a central biological clock, the suprachiasmatic nuclei of the hypothalamus. Preservation of the normal circadian time structure from the level of the cardiomyocyte to the organ system appears to be essential for cardiovascular health and cardiovascular disease prevention. Myocardial ischemia, acute myocardial infarct, and sudden cardiac death are much greater in incidence than expected in the morning. Moreover, supraventricular and ventricular cardiac arrhythmias of various types show specific day-night patterns, with atrial arrhythmias--premature beats, tachycardias, atrial fibrillation, and flutter - generally being of higher frequency during the day than night--and ventricular fibrillation and ventricular premature beats more common, respectively, in the morning and during the daytime activity than sleep span. Furthermore, different circadian patterns of blood pressure are found in arterial hypertension, in relation to different cardiovascular morbidity and mortality risk. Such temporal patterns result from circadian periodicity in pathophysiological mechanisms that give rise to predictable-in-time differences in susceptibility-resistance to cyclic environmental stressors that trigger these clinical events. Circadian rhythms also may affect the pharmacokinetics and pharmacodynamics of cardiovascular and other medications. Knowledge of 24-h patterns in the risk of cardiac arrhythmias and cardiovascular disease morbidity and mortality plus circadian rhythm-dependencies of underlying pathophysiologic mechanisms suggests the requirement for preventive and therapeutic interventions is not the same throughout the day and night, and should be tailored accordingly to improve outcomes.
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21
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Cardiopulmonary arrest and resuscitation disrupts cholinergic anti-inflammatory processes: a role for cholinergic α7 nicotinic receptors. J Neurosci 2011; 31:3446-52. [PMID: 21368056 DOI: 10.1523/jneurosci.4558-10.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cardiac arrest is a leading cause of death worldwide. While survival rates following sudden cardiac arrest remain relatively low, recent advancements in patient care have begun to increase the proportion of individuals who survive cardiac arrest. However, many of these individuals subsequently develop physiological and psychiatric conditions that likely result from ongoing neuroinflammation and neuronal death. The present study was conducted to better understand the pathophysiological effects of cardiac arrest on neuronal cell death and inflammation, and their modulation by the cholinergic system. Using a well validated model of cardiac arrest, here we show that global cerebral ischemia increases microglial activation, proinflammatory cytokine mRNA expression (interleukin-1β, interleukin-6, tumor necrosis factor-α), and neuronal damage. Cardiac arrest also induces alterations in numerous cellular components of central cholinergic signaling, including a reduction in choline acetyltransferase enzymatic activity and the number of choline acetyltransferase-positive neurons, as well as, reduced acetylcholinesterase and vesicular acetylcholine transporter mRNA. However, treatment with a selective agonist of the α7 nicotinic acetylcholine receptor, the primary receptor mediating the cholinergic anti-inflammatory pathway, significantly decreases the neuroinflammation and neuronal damage resulting from cardiac arrest. These data suggest that global cerebral ischemia results in significant declines in central cholinergic signaling, which may in turn diminish the capacity of the cholinergic anti-inflammatory pathway to control inflammation. Furthermore, we provide evidence that pharmacological activation of α7 nicotinic acetylcholine receptors provide significant protection against ischemia-related cell death and inflammation within a clinically relevant time frame.
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