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Amaral-Silva L, Santin J. Neural Processing without O 2 and Glucose Delivery: Lessons from the Pond to the Clinic. Physiology (Bethesda) 2024; 39:0. [PMID: 38624246 PMCID: PMC11573265 DOI: 10.1152/physiol.00030.2023] [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: 11/29/2023] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 04/17/2024] Open
Abstract
Neuronal activity requires a large amount of ATP, leading to a rapid collapse of brain function when aerobic respiration fails. Here, we summarize how rhythmic motor circuits in the brain stem of adult frogs, which normally have high metabolic demands, transform to produce proper output during severe hypoxia associated with emergence from hibernation. We suggest that general principles underlying plasticity in brain bioenergetics may be uncovered by studying nonmammalian models that face extreme environments, yielding new insights to combat neurological disorders involving dysfunctional energy metabolism.
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Affiliation(s)
- Lara Amaral-Silva
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, United States
- Division of Biology, University of Missouri, Columbia, Missouri, United States
| | - Joseph Santin
- Division of Biology, University of Missouri, Columbia, Missouri, United States
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2
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Tian D, Zhang W, Lu L, Yu Y, Yu Y, Zhang X, Li W, Shi W, Liu G. Enrofloxacin exposure undermines gut health and disrupts neurotransmitters along the microbiota-gut-brain axis in zebrafish. CHEMOSPHERE 2024; 356:141971. [PMID: 38604519 DOI: 10.1016/j.chemosphere.2024.141971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/13/2024]
Abstract
The environmental prevalence of antibiotic residues poses a potential threat to gut health and may thereby disrupt brain function through the microbiota-gut-brain axis. However, little is currently known about the impacts of antibiotics on gut health and neurotransmitters along the microbiota-gut-brain axis in fish species. Taking enrofloxacin (ENR) as a representative, the impacts of antibiotic exposure on the gut structural integrity, intestinal microenvironment, and neurotransmitters along the microbiota-gut-brain axis were evaluated in zebrafish in this study. Data obtained demonstrated that exposure of zebrafish to 28-day environmentally realistic levels of ENR (6 and 60 μg/L) generally resulted in marked elevation of two intestinal integrity biomarkers (diamine oxidase (DAO) and malondialdehyde (MDA), upregulation of genes that encode inter-epithelial tight junction proteins, and histological alterations in gut as well as increase of lipopolysaccharide (LPS) in plasma, indicating an evident impairment of the structural integrity of gut. Moreover, in addition to significantly altered neurotransmitters, markedly higher levels of LPS while less amount of two short-chain fatty acids (SCFAs), namely acetic acid and valeric acid, were detected in the gut of ENR-exposed zebrafish, suggesting a disruption of gut microenvironment upon ENR exposure. Along with corresponding changes detected in gut, significant disruption of neurotransmitters in brain indicated by marked alterations in the contents of neurotransmitters, the activity of acetylcholin esterase (AChE), and the expression of neurotransmitter-related genes were also observed. These findings suggest exposure to environmental antibiotic residues may impair gut health and disrupt neurotransmitters along the microbiota-gut-brain axis in zebrafish. Considering the prevalence of antibiotic residues in environments and the high homology of zebrafish to other vertebrates including human, the risk of antibiotic exposure to the health of wild animals as well as human deserves more attention.
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Affiliation(s)
- Dandan Tian
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Weixia Zhang
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Lingzheng Lu
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Yihan Yu
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Yingying Yu
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Xunyi Zhang
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Weifeng Li
- College of Marine Sciences, Guangxi Key Laboratory of Beibu Gulf Marine Biodiversity Conservation, Beibu Gulf University, Qinzhou, 535011, PR China
| | - Wei Shi
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Guangxu Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China.
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3
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Xu S, Kang UG. Region-specific alterations in the expression and phosphorylation of NMDA receptor subunits in the rat prefrontal cortex and dorsal striatum accompanying behavioral sensitization induced by cocaine and ethanol. Pharmacol Biochem Behav 2024; 236:173711. [PMID: 38253241 DOI: 10.1016/j.pbb.2024.173711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 01/24/2024]
Abstract
Behavioral sensitization is defined as the enhanced behavioral response to drugs of abuse after repeated exposure, which can serve as a behavioral model of addiction. Our previous study demonstrated that behavioral cross-sensitization occurs between cocaine and ethanol, suggesting commonalities between these drugs. N-methyl-d-aspartate (NMDA) receptors play important roles in synaptic plasticity, learning, memory, and addiction-associated behaviors. However, little is known about whether NMDA receptor-mediated signaling regulation is a common feature following behavioral sensitizations induced by cocaine and ethanol. Thus, the present study examined the expression of phospho-S896-NR1, NR2A, and NR2B subunits in the prefrontal cortex and dorsal striatum following reciprocal cross-sensitization between cocaine and ethanol. We also examined the mRNA expression of the NR2A and NR2B subunits. In the ethanol-sensitized state, phosphorylation of NR1 and expression of NR2A and NR2B subunits were increased in both the prefrontal cortex and dorsal striatum. In the cocaine-sensitized state, phosphorylation of NR1 and expression of the NR2A and NR2B subunits were increased in the prefrontal cortex but not in the dorsal striatum. Corresponding changes in mRNA expression were observed in the ethanol-sensitized state but not in the cocaine-sensitized state. Acute treatment with either cocaine or ethanol had no effect on the phosphorylation and expression of NMDA receptor subunits in either the prefrontal cortex or dorsal striatum, regardless of the sensitization state. These results indicate a partially overlapping neural mechanism for cocaine and ethanol that may induce the development of behavioral sensitization.
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Affiliation(s)
- Shijie Xu
- Medical Research Center, Affiliated Cancer Hospital of Hainan Medical University, Haikou 570312, China; Institute of Human Behavioral Medicine, Medical Research Center, Seoul National University, Seoul 03080, Republic of Korea
| | - Ung Gu Kang
- Institute of Human Behavioral Medicine, Medical Research Center, Seoul National University, Seoul 03080, Republic of Korea; Department of Psychiatry and Behavioral Science, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
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4
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Krishnan JKS, Rice S, Mikes M, Sugiura MH, Drew KL, Barati Z, Oliver SR. Pre-hibernation diet alters skeletal muscle relaxation kinetics, but not force development in torpid arctic ground squirrels. J Comp Physiol B 2024; 194:65-79. [PMID: 38219236 DOI: 10.1007/s00360-023-01527-z] [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: 10/31/2022] [Revised: 11/10/2023] [Accepted: 11/20/2023] [Indexed: 01/16/2024]
Abstract
During the hibernation season, Arctic ground squirrels (AGS) experience extreme temperature fluctuations (body temperature, Tb, as low as - 3 °C), during which they are mostly physically inactive. Once Tb reaches ~ 15 °C during interbout arousals, hibernators recruit skeletal muscle (SkM) for shivering thermogenesis to reach Tb of ~ 35 °C. Polyunsaturated fatty acids (PUFA) in the diet are known to influence SkM function and metabolism. Recent studies in the cardiac muscle of hibernators have revealed that increased levels of ω-6 and the ω-6:ω-3 PUFA ratio correlate with sarco/endoplasmic reticulum calcium ATPase (SERCA) activity and hibernation status. We hypothesized that diet (increased ω-6:ω-3 PUFA ratio) and torpor status are important in the regulation of the SERCA pump and that this may improve SkM performance during hibernation. Ex vivo functional assays were used to characterize performance changes in SkM (diaphragm) from AGS fed the following diets. (1) Standard rodent chow with an ω-6:ω-3 ratio of 5:1, or (2) a balanced diet with an ω-6:ω-3 ratio of 1:1 that roughly mimics wild diet. We collected diaphragms at three different stages of hibernation (early torpor, late torpor, and arousal) and evaluated muscle function under hypothermic temperature stress at 4 °C, 15 °C, 25 °C, and 37 °C to determine functional resilience. Our data show that torpid animals fed standard rodent chow have faster SkM relaxation when compared to the balanced diet animals. Furthermore, we discovered that standard rodent chow AGS during torpor has higher SkM relaxation kinetics, but this effect of torpor is eliminated in balanced diet AGS. Interestingly, neither diet nor torpor influenced the rate of force development (rate of calcium release). This is the first study to show that increasing the dietary ω-6:ω-3 PUFA ratio improves skeletal muscle performance during decreased temperatures in a hibernating animal. This evidence supports the interpretation that diet can change some functional properties of the SkM, presumably through membrane lipid composition, ambient temperature, and torpor interaction, with an impact on SkM performance.
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Affiliation(s)
- Jishnu K S Krishnan
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Sarah Rice
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Monica Mikes
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - M Hoshi Sugiura
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Kelly L Drew
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Zeinab Barati
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - S Ryan Oliver
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA.
- Department of Chemistry, United States Naval Academy, Annapolis, MD, USA.
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5
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Amaral-Silva L, Santin JM. Synaptic modifications transform neural networks to function without oxygen. BMC Biol 2023; 21:54. [PMID: 36927477 PMCID: PMC10022038 DOI: 10.1186/s12915-023-01518-0] [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: 10/17/2022] [Accepted: 01/18/2023] [Indexed: 03/18/2023] Open
Abstract
BACKGROUND Neural circuit function is highly sensitive to energetic limitations. Much like mammals, brain activity in American bullfrogs quickly fails in hypoxia. However, after emergence from overwintering, circuits transform to function for approximately 30-fold longer without oxygen using only anaerobic glycolysis for fuel, a unique trait among vertebrates considering the high cost of network activity. Here, we assessed neuronal functions that normally limit network output and identified components that undergo energetic plasticity to increase robustness in hypoxia. RESULTS In control animals, oxygen deprivation depressed excitatory synaptic drive within native circuits, which decreased postsynaptic firing to cause network failure within minutes. Assessments of evoked and spontaneous synaptic transmission showed that hypoxia impairs synaptic communication at pre- and postsynaptic loci. However, control neurons maintained membrane potentials and a capacity for firing during hypoxia, indicating that those processes do not limit network activity. After overwintering, synaptic transmission persisted in hypoxia to sustain motor function for at least 2 h. CONCLUSIONS Alterations that allow anaerobic metabolism to fuel synapses are critical for transforming a circuit to function without oxygen. Data from many vertebrate species indicate that anaerobic glycolysis cannot fuel active synapses due to the low ATP yield of this pathway. Thus, our results point to a unique strategy whereby synapses switch from oxidative to exclusively anaerobic glycolytic metabolism to preserve circuit function during prolonged energy limitations.
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Affiliation(s)
- Lara Amaral-Silva
- Division of Biological Sciences, The University of Missouri, Columbia, USA.
| | - Joseph M Santin
- Division of Biological Sciences, The University of Missouri, Columbia, USA.
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6
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Drew KL, Bhowmick S, Laughlin BW, Goropashnaya AV, Tøien Ø, Sugiura MH, Wong A, Pourrezaei K, Barati Z, Chen CY. Opportunities and barriers to translating the hibernation phenotype for neurocritical care. Front Neurol 2023; 14:1009718. [PMID: 36779060 PMCID: PMC9911456 DOI: 10.3389/fneur.2023.1009718] [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: 08/02/2022] [Accepted: 01/11/2023] [Indexed: 01/28/2023] Open
Abstract
Targeted temperature management (TTM) is standard of care for neonatal hypoxic ischemic encephalopathy (HIE). Prevention of fever, not excluding cooling core body temperature to 33°C, is standard of care for brain injury post cardiac arrest. Although TTM is beneficial, HIE and cardiac arrest still carry significant risk of death and severe disability. Mammalian hibernation is a gold standard of neuroprotective metabolic suppression, that if better understood might make TTM more accessible, improve efficacy of TTM and identify adjunctive therapies to protect and regenerate neurons after hypoxic ischemia brain injury. Hibernating species tolerate cerebral ischemia/reperfusion better than humans and better than other models of cerebral ischemia tolerance. Such tolerance limits risk of transitions into and out of hibernation torpor and suggests that a barrier to translate hibernation torpor may be human vulnerability to these transitions. At the same time, understanding how hibernating mammals protect their brains is an opportunity to identify adjunctive therapies for TTM. Here we summarize what is known about the hemodynamics of hibernation and how the hibernating brain resists injury to identify opportunities to translate these mechanisms for neurocritical care.
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Affiliation(s)
- Kelly L. Drew
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Saurav Bhowmick
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Bernard W. Laughlin
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Anna V. Goropashnaya
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Øivind Tøien
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - M. Hoshi Sugiura
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Ardy Wong
- Drexel University School of Biomedical Engineering, Science and Health Systems, Philadelphia, PA, United States
| | - Kambiz Pourrezaei
- Drexel University School of Biomedical Engineering, Science and Health Systems, Philadelphia, PA, United States
| | - Zeinab Barati
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, United States
- Barati Medical LLC, Fairbanks, AK, United States
| | - Chao-Yin Chen
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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7
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Zhao YZ, Wei J, Song KX, Zhou C, Chai Z. Glutamate-aspartate transporter 1 attenuates oxygen-glucose deprivation-induced injury by promoting glutamate metabolism in primary cortical neurons. J Cell Physiol 2022; 237:3044-3056. [PMID: 35551669 DOI: 10.1002/jcp.30768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 11/08/2022]
Abstract
Ischemic stroke is a common cerebral disease. However, the treatment for the disease is limited. Daurian ground squirrel (GS; Spermophilus dauricus), a hibernating mammalian species, is highly tolerant to ischemia. In the present study, GS neurons in a non-hibernating state were found to be more resistant to oxygen-glucose deprivation (OGD), an ischemic model in vitro. We leveraged the differences in the endurance capacity of GS and rats to investigate the mechanisms of resistance to ischemia in GS neurons. We first identified glutamate-aspartate transporter 1 (GLAST) as a cytoprotective factor that contributed to tolerance against OGD injury of GS neurons. The expression of GLAST in GS neurons was much higher than that in rat neurons. Overexpression of GLAST rescued viability in rat neurons, and GS neurons exhibited decreased viability following GLAST knockdown under OGD conditions. Mechanistically, more glutamate was transported into neurons after GLAST overexpression and served as substrates for ATP production. Furthermore, eukaryotic transcription initiation factor 4E binding protein 1 was downregulated by GLAST to rescue neuronal viability. Our findings not only revealed an important molecular mechanism underlying the survival of hibernating mammals but also suggested that neuronal GLAST may be a potential target for ischemic stroke therapy.
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Affiliation(s)
- Yun-Zhi Zhao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
| | - Jun Wei
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
| | - Ke-Xin Song
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
| | - Chen Zhou
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
| | - Zhen Chai
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
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8
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Shi Z, Qin M, Huang L, Xu T, Chen Y, Hu Q, Peng S, Peng Z, Qu LN, Chen SG, Tuo QH, Liao DF, Wang XP, Wu RR, Yuan TF, Li YH, Liu XM. Human torpor: translating insights from nature into manned deep space expedition. Biol Rev Camb Philos Soc 2020; 96:642-672. [PMID: 33314677 DOI: 10.1111/brv.12671] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/09/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022]
Abstract
During a long-duration manned spaceflight mission, such as flying to Mars and beyond, all crew members will spend a long period in an independent spacecraft with closed-loop bioregenerative life-support systems. Saving resources and reducing medical risks, particularly in mental heath, are key technology gaps hampering human expedition into deep space. In the 1960s, several scientists proposed that an induced state of suppressed metabolism in humans, which mimics 'hibernation', could be an ideal solution to cope with many issues during spaceflight. In recent years, with the introduction of specific methods, it is becoming more feasible to induce an artificial hibernation-like state (synthetic torpor) in non-hibernating species. Natural torpor is a fascinating, yet enigmatic, physiological process in which metabolic rate (MR), body core temperature (Tb ) and behavioural activity are reduced to save energy during harsh seasonal conditions. It employs a complex central neural network to orchestrate a homeostatic state of hypometabolism, hypothermia and hypoactivity in response to environmental challenges. The anatomical and functional connections within the central nervous system (CNS) lie at the heart of controlling synthetic torpor. Although progress has been made, the precise mechanisms underlying the active regulation of the torpor-arousal transition, and their profound influence on neural function and behaviour, which are critical concerns for safe and reversible human torpor, remain poorly understood. In this review, we place particular emphasis on elaborating the central nervous mechanism orchestrating the torpor-arousal transition in both non-flying hibernating mammals and non-hibernating species, and aim to provide translational insights into long-duration manned spaceflight. In addition, identifying difficulties and challenges ahead will underscore important concerns in engineering synthetic torpor in humans. We believe that synthetic torpor may not be the only option for manned long-duration spaceflight, but it is the most achievable solution in the foreseeable future. Translating the available knowledge from natural torpor research will not only benefit manned spaceflight, but also many clinical settings attempting to manipulate energy metabolism and neurobehavioural functions.
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Affiliation(s)
- Zhe Shi
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China.,Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.,State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.,Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200030, China
| | - Meng Qin
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Lu Huang
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou, 510632, China
| | - Tao Xu
- Department of Anesthesiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Ying Chen
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China
| | - Qin Hu
- College of Life Sciences and Bio-Engineering, Beijing University of Technology, Beijing, 100024, China
| | - Sha Peng
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Zhuang Peng
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Li-Na Qu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Shan-Guang Chen
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Qin-Hui Tuo
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Duan-Fang Liao
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China
| | - Xiao-Ping Wang
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ren-Rong Wu
- National Clinical Research Center for Mental Disorders, and Department of Psychaitry, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ti-Fei Yuan
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, 200030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226000, China
| | - Ying-Hui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Xin-Min Liu
- Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.,State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.,Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
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9
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Sonntag M, Arendt T. Neuronal Activity in the Hibernating Brain. Front Neuroanat 2019; 13:71. [PMID: 31338028 PMCID: PMC6629779 DOI: 10.3389/fnana.2019.00071] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/26/2019] [Indexed: 11/13/2022] Open
Abstract
Hibernation is a natural phenomenon in many species which helps them to survive under extreme ambient conditions, such as cold temperatures and reduced availability of food in the winter months. It is characterized by a dramatic and regulated drop of body temperature, which in some cases can be near 0°C. Additionally, neural control of hibernation is maintained over all phases of a hibernation bout, including entrance into, during and arousal from torpor, despite a marked decrease in overall neural activity in torpor. In the present review, we provide an overview on what we know about neuronal activity in the hibernating brain focusing on cold-induced adaptations. We discuss pioneer and more recent in vitro and in vivo electrophysiological data and molecular analyses of activity markers which strikingly contributed to our understanding of the brain's sensitivity to dramatic changes in temperature across the hibernation cycle. Neuronal activity is markedly reduced with decreasing body temperature, and many neurons may fire infrequently in torpor at low brain temperatures. Still, there is convincing evidence that specific regions maintain their ability to generate action potentials in deep torpor, at least in response to adequate stimuli. Those regions include the peripheral system and primary central regions. However, further experiments on neuronal activity are needed to more precisely determine temperature effects on neuronal activity in specific cell types and specific brain nuclei.
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Affiliation(s)
- Mandy Sonntag
- Paul-Flechsig-Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Thomas Arendt
- Paul-Flechsig-Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany
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10
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Capraro A, O'Meally D, Waters SA, Patel HR, Georges A, Waters PD. Waking the sleeping dragon: gene expression profiling reveals adaptive strategies of the hibernating reptile Pogona vitticeps. BMC Genomics 2019; 20:460. [PMID: 31170930 PMCID: PMC6555745 DOI: 10.1186/s12864-019-5750-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/29/2019] [Indexed: 12/30/2022] Open
Abstract
Background Hibernation is a physiological state exploited by many animals exposed to prolonged adverse environmental conditions associated with winter. Large changes in metabolism and cellular function occur, with many stress response pathways modulated to tolerate physiological challenges that might otherwise be lethal. Many studies have sought to elucidate the molecular mechanisms of mammalian hibernation, but detailed analyses are lacking in reptiles. Here we examine gene expression in the Australian central bearded dragon (Pogona vitticeps) using mRNA-seq and label-free quantitative mass spectrometry in matched brain, heart and skeletal muscle samples from animals at late hibernation, 2 days post-arousal and 2 months post-arousal. Results We identified differentially expressed genes in all tissues between hibernation and post-arousal time points; with 4264 differentially expressed genes in brain, 5340 differentially expressed genes in heart, and 5587 differentially expressed genes in skeletal muscle. Furthermore, we identified 2482 differentially expressed genes across all tissues. Proteomic analysis identified 743 proteins (58 differentially expressed) in brain, 535 (57 differentially expressed) in heart, and 337 (36 differentially expressed) in skeletal muscle. Tissue-specific analyses revealed enrichment of protective mechanisms in all tissues, including neuroprotective pathways in brain, cardiac hypertrophic processes in heart, and atrophy protective pathways in skeletal muscle. In all tissues stress response pathways were induced during hibernation, as well as evidence for gene expression regulation at transcription, translation and post-translation. Conclusions These results reveal critical stress response pathways and protective mechanisms that allow for maintenance of both tissue-specific function, and survival during hibernation in the central bearded dragon. Furthermore, we provide evidence for multiple levels of gene expression regulation during hibernation, particularly enrichment of miRNA-mediated translational repression machinery; a process that would allow for rapid and energy efficient reactivation of translation from mature mRNA molecules at arousal. This study is the first molecular investigation of its kind in a hibernating reptile, and identifies strategies not yet observed in other hibernators to cope stress associated with this remarkable state of metabolic depression. Electronic supplementary material The online version of this article (10.1186/s12864-019-5750-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexander Capraro
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, UNSW Sydney, Sydney, NSW, 2052, Australia.
| | - Denis O'Meally
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.,Present address: Center for Gene Therapy, Beckman Research Institute of the City of Hope, Duarte, CA, 91010, USA
| | - Shafagh A Waters
- School of Women's & Children's Health, Faculty of Medicine, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Hardip R Patel
- John Curtin School of Medical Research, Australian National University, Canberra, 2601, ACT, Australia
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Paul D Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, UNSW Sydney, Sydney, NSW, 2052, Australia
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11
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Bhowmick S, Drew KL. Mechanisms of innate preconditioning towards ischemia/anoxia tolerance: Lessons from mammalian hibernators. CONDITIONING MEDICINE 2019; 2:134-141. [PMID: 32542230 PMCID: PMC7295161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Hibernating mammals exhibit an innate physiological ability to withstand dramatic fluctuations in blood flow that occurs during hibernation and arousal or experimental models of ischemia reperfusion without significant damage. These innate adaptations are of significance particularly to organs that are highly susceptible to energy deprivation, such as the brain and the heart. Among vertebrates, the arctic ground squirrel (AGS) is a species that tolerates ischemic/anoxic insult. During the process of entering hibernation, a state of prolonged torpor, the AGS undergoes a profound decrease in respiratory rate, heart rate, blood flow, cerebral perfusion, and body temperature (Tb). The reduced level of blood flow during torpor resembles an ischemic state, albeit without energy deficit. During the process of arousal or emergence from torpor, however, when Tb, respiratory rate, heart rate, and blood flow rapidly returns to pre-torpid levels, the rapid return of cerebral blood flow mimics aspects of reperfusion such as is seen after stroke or cardiac arrest. This sublethal ischemic/reperfusion insult experienced by AGS during the process of arousal may precondition AGS to tolerate otherwise lethal ischemic/reperfusion injury induced in the laboratory. In this review, we will summarize some of the mechanisms implemented by mammalian hibernators to combat ischemia/anoxia tolerance.
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Affiliation(s)
- Saurav Bhowmick
- Laboratory of CNS Injury and Repair, JFK Neuroscience Institute, Hackensack Meridian Health JFK Medical Center, 65 James St., Edison, NJ 08820, USA
| | - Kelly L Drew
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
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12
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The hypoxia-tolerant vertebrate brain: Arresting synaptic activity. Comp Biochem Physiol B Biochem Mol Biol 2018; 224:61-70. [DOI: 10.1016/j.cbpb.2017.11.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/23/2017] [Accepted: 11/30/2017] [Indexed: 01/16/2023]
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13
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Abstract
Although it is generally believed that oxidative phosphorylation and adequate oxygenation are essential for life, human development occurs in a profoundly hypoxic environment and "normal" levels of oxygen during embryogenesis are even harmful. The ability of embryos not only to survive but also to thrive in such an environment is made possible by adaptations related to metabolic pathways. Similarly, cancerous cells are able not only to survive but also to grow and spread in environments that would typically be fatal for healthy adult cells. Many biological states, both normal and pathological, share underlying similarities related to metabolism, the electron transport chain, and reactive species. The purpose of Part I of this review is to review the similarities among embryogenesis, mammalian adaptions to hypoxia (primarily driven by hypoxia-inducible factor-1), ischemia-reperfusion injury (and its relationship with reactive oxygen species), hibernation, diving animals, cancer, and sepsis, with a particular focus on the common characteristics that allow cells and organisms to survive in these states.
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Affiliation(s)
- Robert H Thiele
- From the Department of Anesthesiology, University of Virginia, Charlottesville, VA
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14
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Ballinger MA, Schwartz C, Andrews MT. Enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation. Am J Physiol Regul Integr Comp Physiol 2017; 312:R301-R310. [PMID: 28077389 DOI: 10.1152/ajpregu.00314.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 01/06/2017] [Accepted: 01/08/2017] [Indexed: 11/22/2022]
Abstract
During hibernation, thirteen-lined ground squirrels (Ictidomys tridecemlineatus) regularly cycle between bouts of torpor and interbout arousal (IBA). Most of the brain is electrically quiescent during torpor but regains activity quickly upon arousal to IBA, resulting in extreme oscillations in energy demand during hibernation. We predicted increased functional capacity of brain mitochondria during hibernation compared with spring to accommodate the variable energy demands of hibernation. To address this hypothesis, we examined mitochondrial bioenergetics in the ground squirrel brain across three time points: spring (SP), torpor (TOR), and IBA. Respiration rates of isolated brain mitochondria through complex I of the electron transport chain were more than twofold higher in TOR and IBA than in SP (P < 0.05). We also found a 10% increase in membrane potential between hibernation and spring (P < 0.05), and that proton leak was lower in TOR and IBA than in SP. Finally, there was a 30% increase in calcium loading in SP brain mitochondria compared with TOR and IBA (P < 0.01). To analyze brain mitochondrial abundance between spring and hibernation, we measured the ratio of copy number in a mitochondrial gene (ND1) vs. a nuclear gene (B2M) in frozen cerebral cortex samples. No significant differences were observed in DNA copies between SP and IBA. These data show that brain mitochondrial bioenergetics are not static across the year and suggest that brain mitochondria function more effectively during the hibernation season, allowing for rapid production of energy to meet demand when extreme physiological changes are occurring.
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Affiliation(s)
- Mallory A Ballinger
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Christine Schwartz
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and.,Department of Biology, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Matthew T Andrews
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
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15
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Abstract
Many environmental conditions can constrain the ability of animals to obtain sufficient food energy, or transform that food energy into useful chemical forms. To survive extended periods under such conditions animals must suppress metabolic rate to conserve energy, water, or oxygen. Amongst small endotherms, this metabolic suppression is accompanied by and, in some cases, facilitated by a decrease in core body temperature-hibernation or daily torpor-though significant metabolic suppression can be achieved even with only modest cooling. Within some ectotherms, winter metabolic suppression exceeds the passive effects of cooling. During dry seasons, estivating ectotherms can reduce metabolism without changes in body temperature, conserving energy reserves, and reducing gas exchange and its inevitable loss of water vapor. This overview explores the similarities and differences of metabolic suppression among these states within adult animals (excluding developmental diapause), and integrates levels of organization from the whole animal to the genome, where possible. Several similarities among these states are highlighted, including patterns and regulation of metabolic balance, fuel use, and mitochondrial metabolism. Differences among models are also apparent, particularly in whether the metabolic suppression is intrinsic to the tissue or depends on the whole-animal response. While in these hypometabolic states, tissues from many animals are tolerant of hypoxia/anoxia, ischemia/reperfusion, and disuse. These natural models may, therefore, serve as valuable and instructive models for biomedical research.
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Affiliation(s)
- James F Staples
- Department of Biology, University of Western Ontario, London, Ontario, Canada
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16
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Abstract
Food availability determines developmental rate, behavior, and survival of animals. Animals that enter diapause or hibernate in response to lack of food have a double advantage: they are able to adapt to environmental and cellular challenges and survive to these challenges for a prolonged time. The metabolic and physiological adaptations that make possible diapause and hibernation also provide a favorable cellular environment for tissue protection. This review highlights the benefits of dormancy on neuronal protection in the model organism Caenorhabditis elegans and small mammals such as squirrels. Additionally, I discuss the link between metabolic restructuring occurring in diapause and changes in gene expression with the increased capacity of diapausing animals to protect neurons from degeneration and potentially foster their regeneration.
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Affiliation(s)
- Andrea Calixto
- Center for Genomics and Bioinformatics, Faculty of Sciences, Universidad Mayor, Santiago, Chile.
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18
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Larson J, Drew KL, Folkow LP, Milton SL, Park TJ. No oxygen? No problem! Intrinsic brain tolerance to hypoxia in vertebrates. ACTA ACUST UNITED AC 2014; 217:1024-39. [PMID: 24671961 DOI: 10.1242/jeb.085381] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many vertebrates are challenged by either chronic or acute episodes of low oxygen availability in their natural environments. Brain function is especially vulnerable to the effects of hypoxia and can be irreversibly impaired by even brief periods of low oxygen supply. This review describes recent research on physiological mechanisms that have evolved in certain vertebrate species to cope with brain hypoxia. Four model systems are considered: freshwater turtles that can survive for months trapped in frozen-over lakes, arctic ground squirrels that respire at extremely low rates during winter hibernation, seals and whales that undertake breath-hold dives lasting minutes to hours, and naked mole-rats that live in crowded burrows completely underground for their entire lives. These species exhibit remarkable specializations of brain physiology that adapt them for acute or chronic episodes of hypoxia. These specializations may be reactive in nature, involving modifications to the catastrophic sequelae of oxygen deprivation that occur in non-tolerant species, or preparatory in nature, preventing the activation of those sequelae altogether. Better understanding of the mechanisms used by these hypoxia-tolerant vertebrates will increase appreciation of how nervous systems are adapted for life in specific ecological niches as well as inform advances in therapy for neurological conditions such as stroke and epilepsy.
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Affiliation(s)
- John Larson
- Psychiatric Institute, Department of Psychiatry and Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois, Chicago, IL 60612, USA
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Zhao JJ, Gao S, Jing JZ, Zhu MY, Zhou C, Chai Z. Increased Na+/Ca2+ exchanger activity promotes resistance to excitotoxicity in cortical neurons of the ground squirrel (a Hibernator). PLoS One 2014; 9:e113594. [PMID: 25415196 PMCID: PMC4240599 DOI: 10.1371/journal.pone.0113594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 10/29/2014] [Indexed: 11/18/2022] Open
Abstract
Ground squirrel, a hibernating mammalian species, is more resistant to ischemic brain stress than rat. Gaining insight into the adaptive mechanisms of ground squirrels may help us design treatment strategies to reduce brain damage in patients suffering ischemic stroke. To understand the anti-stress mechanisms in ground squirrel neurons, we studied glutamate toxicity in primary cultured neurons of the Daurian ground squirrel (Spermophilus dauricus). At the neuronal level, for the first time, we found that ground squirrel was more resistant to glutamate excitotoxicity than rat. Mechanistically, ground squirrel neurons displayed a similar calcium influx to the rat neurons in response to glutamate or N-methyl-D-aspartate (NMDA) perfusion. However, the rate of calcium removal in ground squirrel neurons was markedly faster than in rat neurons. This allows ground squirrel neurons to maintain lower level of intracellular calcium concentration ([Ca2+]i) upon glutamate insult. Moreover, we found that Na+/Ca2+ exchanger (NCX) activity was higher in ground squirrel neurons than in rat neurons. We also proved that overexpression of ground squirrel NCX2, rather than NCX1 or NCX3, in rat neurons promoted neuron survival against glutamate toxicity. Taken together, our results indicate that ground squirrel neurons are better at maintaining calcium homeostasis than rat neurons and this is likely achieved through the activity of ground squirrel NCX2. Our findings not only reveal an adaptive mechanism of mammalian hibernators at the cellular level, but also suggest that NCX2 of ground squirrel may have therapeutic value for suppressing brain ischemic damage.
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Affiliation(s)
- Juan-Juan Zhao
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Shan Gao
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Jun-Zhan Jing
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Ming-Yue Zhu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Chen Zhou
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Zhen Chai
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
- * E-mail:
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20
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Abstract
Decreased oxygen availability impairs cellular energy production and, without a coordinated and matched decrease in energy consumption, cellular and whole organism death rapidly ensues. Of particular interest are mechanisms that protect brain from low oxygen injury, as this organ is not only the most sensitive to hypoxia, but must also remain active and functional during low oxygen stress. As a result of natural selective pressures, some species have evolved molecular and physiological mechanisms to tolerate prolonged hypoxia with no apparent detriment. Among these mechanisms are a handful of responses that are essential for hypoxia tolerance, including (i) sensors that detect changes in oxygen availability and initiate protective responses; (ii) mechanisms of energy conservation; (iii) maintenance of basic brain function; and (iv) avoidance of catastrophic cell death cascades. As the study of hypoxia-tolerant brain progresses, it is becoming increasingly apparent that mitochondria play a central role in regulating all of these critical mechanisms. Furthermore, modulation of mitochondrial function to mimic endogenous neuroprotective mechanisms found in hypoxia-tolerant species confers protection against otherwise lethal hypoxic stresses in hypoxia-intolerant organs and organisms. Therefore, lessons gleaned from the investigation of endogenous mechanisms of hypoxia tolerance in hypoxia-tolerant organisms may provide insight into clinical pathologies related to low oxygen stress.
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Affiliation(s)
- Matthew E. Pamenter
- Department of Zoology, The University of British Columbia, #4200-6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
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21
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Mielke JG. Susceptibility to oxygen-glucose deprivation is reduced in acute hippocampal slices from euthermic Syrian golden hamsters relative to slices from Sprague-Dawley rats. Neurosci Lett 2013; 553:13-7. [PMID: 23933209 DOI: 10.1016/j.neulet.2013.07.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 07/24/2013] [Accepted: 07/27/2013] [Indexed: 02/06/2023]
Abstract
Hibernation in mammals is characterised by a marked decrease in body temperature and a dramatic suppression of metabolism. In addition, despite experiencing a reduced cardiac output that would normally cause profound cerebral ischaemia, hibernating animals display robust neuroprotection. However, whether the reduced susceptibility to neural injury displayed by hibernators is attributable to an innate factor, or to the physiologic changes that accompany hibernation, remains uncertain. To help clarify the nature of the ischaemic tolerance displayed by hibernators, the current study examined hippocampal slices from rodents not capable of hibernation (rat) and rodents that could undergo hibernation (hamsters), but were active immediately prior to slice preparation. Slices from each species were subjected to oxygen-glucose deprivation (OGD; a commonly used in vitro model of ischaemia), and their viability examined after a recovery period. Although OGD reduced plasma membrane integrity in each species, rat-derived slices displayed a nearly threefold greater degree of effect. In addition, only slices harvested from rats showed reductions in synaptic mitochondrial function. While the improved ischaemic tolerance displayed by euthermic hamster brain slices maintained at a physiological temperature suggests an intrinsic, protection-related variable, the synaptic level of the GluN1 subunit (which is required to form functional NMDA receptors) was not found to be different between the two species. Further work is needed to improve understanding of the molecular mechanisms underlying the intrinsic injury tolerance of hibernator brain, which should help provide inspiration for new approaches to neuroprotection.
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Affiliation(s)
- John G Mielke
- School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada.
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22
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Arendt T, Bullmann T. Neuronal plasticity in hibernation and the proposed role of the microtubule-associated protein tau as a "master switch" regulating synaptic gain in neuronal networks. Am J Physiol Regul Integr Comp Physiol 2013; 305:R478-89. [PMID: 23824962 DOI: 10.1152/ajpregu.00117.2013] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present paper provides an overview of adaptive changes in brain structure and learning abilities during hibernation as a behavioral strategy used by several mammalian species to minimize energy expenditure under current or anticipated inhospitable environmental conditions. One cellular mechanism that contributes to the regulated suppression of metabolism and thermogenesis during hibernation is reversible phosphorylation of enzymes and proteins, which limits rates of flux through metabolic pathways. Reversible phosphorylation during hibernation also affects synaptic membrane proteins, a process known to be involved in synaptic plasticity. This mechanism of reversible protein phosphorylation also affects the microtubule-associated protein tau, thereby generating a condition that in the adult human brain is associated with aggregation of tau protein to paired helical filaments (PHFs), as observed in Alzheimer's disease. Here, we put forward the concept that phosphorylation of tau is a neuroprotective mechanism to escape NMDA-mediated hyperexcitability of neurons that would otherwise occur during slow gradual cooling of the brain. Phosphorylation of tau and its subsequent targeting to subsynaptic sites might, thus, work as a kind of "master switch," regulating NMDA receptor-mediated synaptic gain in a wide array of neuronal networks, thereby enabling entry into torpor. If this condition lasts too long, however, it may eventually turn into a pathological trigger, driving a cascade of events leading to neurodegeneration, as in Alzheimer's disease or other "tauopathies".
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Affiliation(s)
- Thomas Arendt
- Paul Flechsig Institute of Brain Research, Universität Leipzig, Germany.
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23
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Zhu Y, Wang Y, Zhao B, Wei S, Xu M, Liu E, Lai J. Differential phosphorylation of GluN1-MAPKs in rat brain reward circuits following long-term alcohol exposure. PLoS One 2013; 8:e54930. [PMID: 23372792 PMCID: PMC3553008 DOI: 10.1371/journal.pone.0054930] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 12/17/2012] [Indexed: 01/19/2023] Open
Abstract
The effects of long-term alcohol consumption on the mitogen-activated protein kinases (MAPKs) pathway and N-methyl-D-aspartate-type glutamate receptor 1 (GluN1) subunits in the mesocorticolimbic system remain unclear. In the present study, rats were allowed to consume 6% (v/v) alcohol solution for 28 consecutive days. Locomotor activity and behavioral signs of withdrawal were observed. Phosphorylation and expression of extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), p38 protein kinase and GluN1 in the nucleus accumbens, caudate putamen, amygdala, hippocampus and prefrontal cortex of these rats were also measured. Phosphorylation of ERK, but not JNK or p38, was decreased in all five brain regions studied in alcohol-drinking rats. The ratio of phospho/total-GluN1 subunit was reduced in all five brain regions studied. Those results suggest that the long-term alcohol consumption can inhibits GluN1 and ERK phosphorylation, but not JNK or p38 in the mesocorticolimbic system, and these changes may be relevant to alcohol dependence. To differentiate alcohol-induced changes in ERK and GluN1 between acute and chronic alcohol exposure, we have determined levels of phospho-ERK, phospho-GluN1 and total levels of GluN1 after acute alcohol exposure. Our data show that 30 min following a 2.5 g/kg dose of alcohol (administered intragastrically), levels of phospho-ERK are decreased while those of phospho-GluN1 are elevated with no change in total GluN1 levels. At 24 h following the single alcohol dose, levels of phospho-ERK are elevated in several brain regions while there are no differences between controls and alcohol treated animals in phospho-GluN1 or total GluN1. Those results suggest that alcohol may differentially regulate GluN1 function and ERK activation depending on alcohol dose and exposure time in the central nervous system.
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Affiliation(s)
- Yongsheng Zhu
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, China
- Key Laboratory of Fertility Preservation and Maintenance, Ningxia Medical University, Ministry of Education, Yinchuan, China
| | - Yunpeng Wang
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, China
| | - Bin Zhao
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, China
| | - Shuguang Wei
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, China
| | - Ming Xu
- Department of Anesthesia and Critical Care, The University of Chicago, Chicago, Illinois, United States of America
| | - Enqi Liu
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, China
| | - Jianghua Lai
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, China
- Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education, Xi’an, China
- * E-mail:
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Potentially neuroprotective gene modulation in an in vitro model of mild traumatic brain injury. Mol Cell Biochem 2012; 375:185-98. [PMID: 23242602 DOI: 10.1007/s11010-012-1541-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/06/2012] [Indexed: 01/21/2023]
Abstract
In this study, we investigated the hypothesis that mild traumatic brain injury (mTBI) triggers a controlled gene program as an adaptive response finalized to neuroprotection, similar to that found in hibernators and in ischemic preconditioning. A stretch injury device was used to produce an equi-biaxial strain field in rat organotypic hippocampal slice cultures at a specified Lagrangian strain of 10 % and a constant strain rate of 20 s(-1). After 24 h from injury, propidium iodide staining, HPLC analysis of metabolites and microarray analysis of cDNA were performed to evaluate cell viability, cell energy state and gene expression, respectively. Compared to control cultures, 10 % stretch injured cultures showed no change in viability, but demonstrated a hypometabolic state (decreased ATP, ATP/ADP, and nicotinic coenzymes) and a peculiar pattern of gene modulation. The latter was characterized by downregulation of genes encoding for proteins of complexes I, III, and IV of the mitochondrial electron transport chain and of ATP synthase; downregulation of transcriptional and translational genes; downregulation and upregulation of genes controlling the synthesis of glutamate and GABA receptors, upregulation of calmodulin and calmodulin-binding proteins; proper modulation of genes encoding for proapoptotic and antiapoptotic proteins. These results support the hypothesis that, following mTBI, a hibernation-type response is activated in non-hibernating species. Unlike in hibernators and ischemic preconditioning, this adaptive gene programme, aimed at achieving maximal neuroprotection, is not triggered by decrease in oxygen availability. It seems rather activated to avoid increase in oxidative/nitrosative stress and apoptosis during a transient period of mitochondrial malfunctioning.
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Dave KR, Christian SL, Perez-Pinzon MA, Drew KL. Neuroprotection: lessons from hibernators. Comp Biochem Physiol B Biochem Mol Biol 2012; 162:1-9. [PMID: 22326449 PMCID: PMC3334476 DOI: 10.1016/j.cbpb.2012.01.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 01/26/2012] [Accepted: 01/30/2012] [Indexed: 12/15/2022]
Abstract
Mammals that hibernate experience extreme metabolic states and body temperatures as they transition between euthermia, a state resembling typical warm blooded mammals, and prolonged torpor, a state of suspended animation where the brain receives as low as 10% of normal cerebral blood flow. Transitions into and out of torpor are more physiologically challenging than the extreme metabolic suppression and cold body temperatures of torpor per se. Mammals that hibernate show unprecedented capacities to tolerate cerebral ischemia, a decrease in blood flow to the brain caused by stroke, cardiac arrest or brain trauma. While cerebral ischemia often leads to death or disability in humans and most other mammals, hibernating mammals suffer no ill effects when blood flow to the brain is dramatically decreased during torpor or experimentally induced during euthermia. These animals, as adults, also display rapid and pronounced synaptic flexibility where synapses retract during torpor and rapidly re-emerge upon arousal. A variety of coordinated adaptations contribute to tolerance of cerebral ischemia in these animals. In this review we discuss adaptations in heterothermic mammals that may suggest novel therapeutic targets and strategies to protect the human brain against cerebral ischemic damage and neurodegenerative disease.
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Affiliation(s)
- Kunjan R Dave
- Cerebral Vascular Disease Research Laboratories, Department of Neurology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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Adult naked mole-rat brain retains the NMDA receptor subunit GluN2D associated with hypoxia tolerance in neonatal mammals. Neurosci Lett 2011; 506:342-5. [PMID: 22155615 DOI: 10.1016/j.neulet.2011.11.042] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 11/03/2011] [Accepted: 11/23/2011] [Indexed: 11/20/2022]
Abstract
Adult naked mole-rats show a number of systemic adaptations to a crowded underground habitat that is low in oxygen and high in carbon dioxide. Remarkably, brain slice tissue from adult naked mole-rats also is extremely tolerant to oxygen deprivation as indicated by maintenance of synaptic transmission under hypoxic conditions as well as by a delayed neuronal depolarization during anoxia. These characteristics resemble hypoxia tolerance in brain slices from neonates in a variety of mammal species. An important component of neonatal tolerance to hypoxia involves the subunit composition of NMDA receptors. Neonates have a high proportion of NMDA receptors with GluN2D subunits which are protective because they retard calcium entry into neurons during hypoxic episodes. Therefore, we hypothesized that adult naked mole-rats retain a protective, neonatal-like, NMDA receptor subunit profile. We used immunoblotting to assess age-related changes in NMDA receptor subunits in naked mole-rats and mice. The results show that adult naked mole-rat brain retains a much greater proportion of the hypoxia-protective GluN2D subunit compared to adult mice. However, age-related changes in other subunits (GluN2A and GluN2B) from the neonatal period to adulthood were comparable in mice and naked mole-rats. Hence, adult naked mole-rat brain only retains the neonatal NMDA receptor subunit that is associated with hypoxia tolerance.
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Alò R, Avolio E, Carelli A, Facciolo RM, Canonaco M. Amygdalar glutamatergic neuronal systems play a key role on the hibernating state of hamsters. BMC Neurosci 2011; 12:10. [PMID: 21251260 PMCID: PMC3031265 DOI: 10.1186/1471-2202-12-10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 01/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Excitatory transmitting mechanisms are proving to play a critical role on neuronal homeostasis conditions of facultative hibernators such as the Syrian golden hamster. Indeed works have shown that the glutamatergic system of the main olfactory brain station (amygdala) is capable of controlling thermoregulatory responses, which are considered vital for the different hibernating states. In the present study the role of amygdalar glutamatergic circuits on non-hibernating (NHIB) and hibernating (HIB) hamsters were assessed on drinking stimuli and subsequently compared to expression variations of some glutamatergic subtype mRNA levels in limbic areas. For this study the two major glutamatergic antagonists and namely that of N-methyl-D-aspartate receptor (NMDAR), 3-(+)-2-carboxypiperazin-4-yl-propyl-1-phosphonate (CPP) plus that of the acid α-amine-3-hydroxy-5-methyl-4-isoxazol-propionic receptor (AMPAR) site, cyano-7-nitro-quinoxaline-2,3-dione (CNQX) were infused into the basolateral amygdala nucleus. Attempts were made to establish the type of effects evoked by amygdalar glutamatergic cross-talking processes during drinking stimuli, a response that may corroborate their major role at least during some stages of this physiological activity in hibernators. RESULTS From the behavioral results it appears that the two glutamatergic compounds exerted distinct effects. In the first case local infusion of basolateral complexes (BLA) with NMDAR antagonist caused very great (p < 0.001) drinking rhythms while moderately increased feeding (p < 0.05) responses during arousal with respect to moderately increased drinking levels in euthermics. Conversely, treatment with CNQX did not modify drinking rhythms and so animals spent more time executing exploratory behaviors. These same antagonists accounted for altered glutamatergic transcription activities as displayed by greatly reduced GluR1, NR1 and GluR2 levels in hippocampus, ventromedial hypothalamic nucleus (VMN) and amygdala, respectively, plus a great (p < 0.01) up-regulation of GluR2 in VMN of hibernators. CONCLUSION We conclude that predominant drinking events evoked by glutamatergic mechanisms, in the presence of prevalently down regulated levels of NR1/2A of some telencephalic and hypothalamic areas appear to constitute an important neuronal switch at least during arousal stage of hibernation. The establishment of the type of glutamatergic subtypes that are linked to successful hibernating states, via drinking stimuli, may have useful bearings toward sleeping disorders.
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Affiliation(s)
- Raffaella Alò
- Comparative Neuroanatomy Laboratory of Ecology Department, University of Calabria, Ponte Pietro Bucci, 87030 Arcavacata di Rende, Cosenza, Italy
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Dave KR, Anthony Defazio R, Raval AP, Dashkin O, Saul I, Iceman KE, Perez-Pinzon MA, Drew KL. Protein kinase C epsilon activation delays neuronal depolarization during cardiac arrest in the euthermic arctic ground squirrel. J Neurochem 2009; 110:1170-9. [PMID: 19493168 PMCID: PMC2774829 DOI: 10.1111/j.1471-4159.2009.06196.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
During the pre-hibernation season, arctic ground squirrels (AGS) can tolerate 8 min of asphyxial cardiac arrest (CA) without detectable brain pathology. Better understanding of the mechanisms regulating innate ischemia tolerance in AGS has the potential to facilitate the development of novel prophylactic agents to induce ischemic tolerance in patients at risk of stroke or CA. We hypothesized that neuroprotection in AGS involves robust maintenance of ion homeostasis similar to anoxia-tolerant turtles. Ion homeostasis was assessed by monitoring ischemic depolarization (ID) in cerebral cortex during CA in vivo and during oxygen glucose deprivation in vitro in acutely prepared hippocampal slices. In both models, the onset of ID was significantly delayed in AGS compared with rats. The epsilon protein kinase C (epsilonPKC) is a key mediator of neuroprotection and inhibits both Na+/K+-ATPase and voltage-gated sodium channels, primary mediators of the collapse of ion homeostasis during ischemia. The selective peptide inhibitor of epsilonPKC (epsilonV1-2) shortened the time to ID in brain slices from AGS but not in rats despite evidence that epsilonV1-2 decreased activation of epsilonPKC in brain slices from both rats and AGS. These results support the hypothesis that epsilonPKC activation delays the collapse of ion homeostasis during ischemia in AGS.
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Affiliation(s)
- Kunjan R Dave
- Department of Neurology, Cerebral Vascular Disease Research Center, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida 33101, USA.
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Shimmyo Y, Kihara T, Akaike A, Niidome T, Sugimoto H. Three distinct neuroprotective functions of myricetin against glutamate-induced neuronal cell death: involvement of direct inhibition of caspase-3. J Neurosci Res 2008; 86:1836-45. [PMID: 18265412 DOI: 10.1002/jnr.21629] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The excitatory neurotransmitter glutamate can accumulate in the brain and is thought to be involved in the etiology of many neurodegenerative disorders, including ischemia and Alzheimer disease. Therefore, it is important to search for compounds that reduce glutamate neurotoxicity. This glutamate-mediated excitotoxicity is caused by intracellular Ca2+ overload via the N-methyl-D-aspartate receptor NMDAR), reactive oxygen species (ROS) generation, and caspase-3 activation. Here we show that the natural flavonoid myricetin inhibited glutamate-induced excitotoxicity and protected neurons by multiple, distinct pathways. First, myricetin affected modulation of the NMDAR by phosphorylation, causing a subsequent reduction in glutamate-induced intracellular Ca2+ overload. Second, myricetin inhibited the ROS production caused by glutamate. Finally, glutamate-induced activation of caspase-3 was reduced by myricetin treatment. Moreover, myricetin directly interacted with the active site of caspase-3 via three hydrogen bonds and inhibited its activity. We conclude that myricetin inhibited glutamate-induced neuronal toxicity by multiple biochemical pathways. These results show that myricetin is a potent antineurodegenerative compound and may contribute to the discovery of a drug with which to combat neurodegeneration.
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Affiliation(s)
- Yoshiari Shimmyo
- Department of Neuroscience for Drug Discovery, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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van Tellingen C. Heaven can wait - or down to earth in real time: Near-death experience revisited. Neth Heart J 2008; 16:359-62. [PMID: 18958261 PMCID: PMC2570769 DOI: 10.1007/bf03086179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Near-death experience (NDE) is an intriguing phenomenon that invites more questions than answers. Hitherto emphasis has been laid on apparent similarities in accounts of NDE to prove a supernatural origin while in fact unique differences besides gross similarities support a neurophysiological explanation. A teleological approach is suggested to explain the neuroprotective strategies involved and accordingly a forme fruste of the biological concept of hibernation is put forward as an unifying hypothesis for clarification. (Neth Heart J 2008;16:359-62.).
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Weil ZM, Norman GJ, DeVries AC, Nelson RJ. The injured nervous system: a Darwinian perspective. Prog Neurobiol 2008; 86:48-59. [PMID: 18602443 DOI: 10.1016/j.pneurobio.2008.06.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 04/28/2008] [Accepted: 06/09/2008] [Indexed: 12/11/2022]
Abstract
Much of the permanent damage that occurs in response to nervous system damage (trauma, infection, ischemia, etc.) is mediated by endogenous secondary processes that can contribute to cell death and tissue damage (excitotoxicity, oxidative damage and inflammation). For humans to evolve mechanisms to minimize secondary pathophysiological events following CNS injuries, selection must occur for individuals who survive such insults. Two major factors limit the selection for beneficial responses to CNS insults: for many CNS disease states the principal risk factor is advanced, post-reproductive age and virtually all severe CNS traumas are fatal in the absence of modern medical intervention. An alternative hypothesis for the persistence of apparently maladaptive responses to CNS damage is that the secondary exacerbation of damage is the result of unavoidable evolutionary constraints. That is, the nervous system could not function under normal conditions if the mechanisms that caused secondary damage (e.g., excitotoxicity) in response to injury were decreased or eliminated. However, some vertebrate species normally inhabit environments (e.g., hypoxia in underground burrows) that could potentially damage their nervous systems. Yet, neuroprotective mechanisms have evolved in these animals indicating that natural selection can occur for traits that protect animals from nervous system damage. Many of the secondary processes and regeneration-inhibitory factors that exacerbate injuries likely persist because they have been adaptive over evolutionary time in the healthy nervous system. Therefore, it remains important that researchers consider the role of the processes in the healthy or developing nervous system to understand how they become dysregulated following injury.
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Affiliation(s)
- Zachary M Weil
- Departments of Psychology and Neuroscience, Institute for Behavioral Medicine Research, The Ohio State University, Columbus, OH 43210, USA.
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Zhao HW, Christian SL, Castillo MR, Bult-Ito A, Drew KL. Distribution of NMDA receptor subunit NR1 in arctic ground squirrel central nervous system. J Chem Neuroanat 2006; 32:196-207. [PMID: 17097266 PMCID: PMC3796384 DOI: 10.1016/j.jchemneu.2006.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 09/13/2006] [Accepted: 09/13/2006] [Indexed: 10/23/2022]
Abstract
Hibernation is a natural model of neuroprotection and adult synaptic plasticity. NMDA receptors (NMDAR), which play key roles in excitotoxicity and synaptic plasticity, have not been characterized in a hibernating species. Tolerance to excitotoxicity and cognitive enhancement in Arctic ground squirrels (AGS, Spermophilus parryii) suggests that NMDAR expression may decrease in hibernation and increase upon arousal. NMDAR consist of at least one NMDAR1 (NR1) subunit, which is required for receptor function. Localization of NR1 reflects localization of the majority, if not all, NMDAR complexes. The purpose of this study, therefore, was to characterize the distribution of NR1 subunits in AGS central nervous system using immunohistochemistry. In addition, we compare NR1 expression in hippocampus of hibernating AGS (hAGS) and inter-bout euthermic AGS (ibeAGS) and assess changes in cell somata size using NR1 stained sections in three hippocampal sub-regions (CA1, CA3, and dentate gyrus). For the first time, we report that immunoreactivity of anti-NR1 is widely distributed throughout the central nervous system in AGS and is similar to other species. No differences exist in the expression and distribution of NR1 in hAGS and ibeAGS. However, we report a significant decrease in size of hippocampal CA1 and dentate gyrus NR1-expressing neuronal somata during hibernation torpor.
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Affiliation(s)
- Huiwen W Zhao
- Alaskan Basic Neuroscience Program, Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA.
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