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Liu N, Zhang XL, Jiang SY, Shi JH, Cui JH, Liu XL, Han LH, Gong KR, Yan SC, Xie W, Zhang CY, Shao G. Neuroprotective mechanisms of DNA methyltransferase in a mouse hippocampal neuronal cell line after hypoxic preconditioning. Neural Regen Res 2020; 15:2362-2368. [PMID: 32594061 PMCID: PMC7749487 DOI: 10.4103/1673-5374.285003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Hypoxic preconditioning has been shown to improve hypoxic tolerance in mice, accompanied by the downregulation of DNA methyltransferases (DNMTs) in the brain. However, the roles played by DNMTs in the multiple neuroprotective mechanisms associated with hypoxic preconditioning remain poorly understood. This study aimed to establish an in vitro model of hypoxic preconditioning, using a cultured mouse hippocampal neuronal cell line (HT22 cells), to examine the effects of DNMTs on the endogenous neuroprotective mechanisms that occur during hypoxic preconditioning. HT22 cells were divided into a control group, which received no exposure to hypoxia, a hypoxia group, which was exposed to hypoxia once, and a hypoxic preconditioning group, which was exposed to four cycles of hypoxia. To test the ability of hypoxic preadaptation to induce hypoxic tolerance, cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium assay. Cell viability improved in the hypoxic preconditioning group compared with that in the hypoxia group. The effects of hypoxic preconditioning on the cell cycle and apoptosis in HT22 cells were examined by western blot assay and flow cytometry. Compared with the hypoxia group, the expression levels of caspase-3 and spectrin, which are markers of early apoptosis and S-phase arrest, respectively, noticeably reduced in the hypoxic preconditioning group. Finally, enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and western blot assay were used to investigate the changes in DNMT expression and activity during hypoxic preconditioning. The results showed that compared with the control group, hypoxic preconditioning downregulated the expression levels of DNMT3A and DNMT3B mRNA and protein in HT22 cells and decreased the activities of total DNMTs and DNMT3B. In conclusion, hypoxic preconditioning may exert anti-hypoxic neuroprotective effects, maintaining HT22 cell viability and inhibiting cell apoptosis. These neuroprotective mechanisms may be associated with the inhibition of DNMT3A and DNMT3B.
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Affiliation(s)
- Na Liu
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Xiao-Lu Zhang
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Shu-Yuan Jiang
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Jing-Hua Shi
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Jun-He Cui
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Xiao-Lei Liu
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Li-Hong Han
- Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Ke-Rui Gong
- Department of Oral and Maxillofacial Surgery, University of California San Francsico, San Francisco, CA, USA
| | - Shao-Chun Yan
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Wei Xie
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Chun-Yang Zhang
- Department of Neurosurgery, the First Affiliated Hospital of Baotou Medical College, Baotou, Inner Mongolia Autonomous Region, China
| | - Guo Shao
- Inner Mongolia Key Laboratory of Hypoxic Translational Medicine; Biomedicine Research Center, Basic Medical College and Baotou Medical College of Neuroscience Institute, Baotou Medical College, Baotou, Inner Mongolia Autonomous Region; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing; Department of Neurosurgery, the First Affiliated Hospital of Baotou Medical College, Baotou, Inner Mongolia Autonomous Region,, China
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Lanigan S, Corcoran AE, Wall A, Mukandala G, O'Connor JJ. Acute hypoxic exposure and prolyl-hydroxylase inhibition improves synaptic transmission recovery time from a subsequent hypoxic insult in rat hippocampus. Brain Res 2018; 1701:212-218. [PMID: 30244114 DOI: 10.1016/j.brainres.2018.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 09/14/2018] [Accepted: 09/18/2018] [Indexed: 01/18/2023]
Abstract
In the CNS short episodes of acute hypoxia can result in a decrease in synaptic transmission which may be fully reversible upon re-oxygenation. Stabilization of hypoxia-inducible factor (HIF) by inhibition of prolyl hydroxylase domain (PHD) enzymes has been shown to regulate the cellular response to hypoxia and confer neuroprotection both in vivo and in vitro. Hypoxic preconditioning has become a novel therapeutic target to induce neuroprotection during hypoxic insults. However, there is little understanding of the effects of repeated hypoxic insults or pharmacological PHD inhibition on synaptic signaling. In this study we have assessed the effects of hypoxic exposure and PHD inhibition on synaptic transmission in the rat CA1 hippocampus. Field excitatory postsynaptic potentials (fEPSPs) were elicited by stimulation of the Schaffer collateral pathway. 30 min hypoxia (gas mixture 95% N2/5% CO2) resulted in a significant and fully reversible decrease in fEPSP slope associated with decreases in partial pressures of tissue oxygen. 15-30 min of hypoxia was sufficient to induce stabilization of HIF in hippocampal slices. Exposure to a second hypoxic insult after 60 min resulted in a similar depression of fEPSP slope but with a significantly greater rate of recovery of the fEPSP. Prior single treatment of slices with the PHD inhibitor, dimethyloxalylglycine (DMOG) also resulted in a significantly greater rate of recovery of fEPSP post hypoxia. These results suggest that hypoxia and 'pseudohypoxia' preconditioning may improve the rate of recovery of hippocampal neurons to a subsequent acute hypoxia.
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Affiliation(s)
- Sinead Lanigan
- UCD School of Biomolecular & Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Alan E Corcoran
- UCD School of Biomolecular & Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Audrey Wall
- UCD School of Biomolecular & Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Gatambwa Mukandala
- College of Natural and Applied Sciences, University of Dar-Es-Salaam (UDSM), P.O Box 35064, Dar-Es-Salaam, Tanzania
| | - John J O'Connor
- UCD School of Biomolecular & Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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Biological networks in ischemic tolerance - rethinking the approach to clinical conditioning. Transl Stroke Res 2014; 4:114-29. [PMID: 24223074 DOI: 10.1007/s12975-012-0244-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The adaptive response (conditioning) to environmental stressors evokes evolutionarily conserved programs in uni- and multicellular organisms that result in increased fitness and resistance to stressor induced injury. Although the concept of conditioning has been around for a while, its translation into clinical therapies targeting neurovascular diseases has only recently begun. The slow pace of clinical adoption might be partially explained by our poor understanding of underpinning mechanisms and of the complex responses of the organism to the stressor. At the 2(nd) Translational Preconditioning Meeting participants engaged in an intense discussion addressing whether the time has come to more aggressively implement clinical conditioning protocols in the treatment of cerebrovascular diseases or whether it would be better to wait until preclinical data would help to minimize clinical empiricism. This review addresses the complex involvement of biological networks in establishing ischemic tolerance at the organism level using two clinically promising conditioning modalities, namely remote ischemic preconditioning, and per- or post-conditioning, as examples.
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Stetler RA, Leak RK, Gan Y, Li P, Zhang F, Hu X, Jing Z, Chen J, Zigmond MJ, Gao Y. Preconditioning provides neuroprotection in models of CNS disease: paradigms and clinical significance. Prog Neurobiol 2014; 114:58-83. [PMID: 24389580 PMCID: PMC3937258 DOI: 10.1016/j.pneurobio.2013.11.005] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 12/14/2022]
Abstract
Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, surgical brain injury, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of "cross-tolerance," in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning.
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Affiliation(s)
- R Anne Stetler
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China; Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA; Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA 15261, USA
| | - Rehana K Leak
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, Pittsburgh, PA 15282, USA
| | - Yu Gan
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China; Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA
| | - Peiying Li
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China; Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA
| | - Feng Zhang
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China; Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA; Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA 15261, USA
| | - Xiaoming Hu
- Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA; Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA 15261, USA
| | - Zheng Jing
- Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA; Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA 15261, USA
| | - Jun Chen
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China; Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA; Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA 15261, USA
| | - Michael J Zigmond
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China; Department of Neurology and Center of Cerebrovascular Disease Research, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15213, USA
| | - Yanqin Gao
- State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University, Shanghai Medical College, Shanghai 200032, China.
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Wall AM, Corcoran AE, O'Halloran KD, O'Connor JJ. Effects of prolyl-hydroxylase inhibition and chronic intermittent hypoxia on synaptic transmission and plasticity in the rat CA1 and dentate gyrus. Neurobiol Dis 2013; 62:8-17. [PMID: 24055213 DOI: 10.1016/j.nbd.2013.08.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/07/2013] [Accepted: 08/14/2013] [Indexed: 01/11/2023] Open
Abstract
Chronic intermittent hypoxia (CIH) is an underlying component of obstructive sleep apnoea and has been shown to have deleterious and damaging effects on central neurons and to impair synaptic plasticity in the CA1 region of the rat hippocampus. CIH has previously been shown to impair synaptic plasticity and working memory. CIH is a potent inducer of hypoxia inducible factor (HIF), a key regulator in a cell's adaptation to hypoxia that plays an important role in the fate of neurons during ischemia. Levels of HIF-1α are regulated by the activity of a group of enzymes called HIF-prolyl 4-hydroxylases (PHDs) and these have become potential pharmacological targets for preconditioning against ischemia. However little is known about the effects of prolyl hydroxylase inhibition and CIH on synaptic transmission and plasticity in sub-regions of the hippocampus. Male Wistar rats were treated for 7-days with either saline, CIH or PHD inhibition (dimethyloxaloylglycine, DMOG; 50mg/kg, i.p.). At the end of treatment all three groups showed no change in synaptic excitability using paired pulse paradigms. However long-term potentiation (LTP) was impaired in the CA1 region of the hippocampus in both CIH and DMOG treated animals. LTP induced in the dentate gyrus was not significantly affected by either CIH or DMOG treatment. We also investigated the effect of 7-day CIH and DMOG treatment on the recovery of synaptic transmission following an acute 30min hypoxic insult. CIH treated animals showed an improved rate of recovery of synaptic transmission following re-oxygenation in both the CA1 and the dentate gyrus. These results suggest that LTP induction in the CA1 region is more sensitive to both CIH and DMOG treatments than the dentate gyrus.
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Affiliation(s)
- Audrey M Wall
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Alan E Corcoran
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, University College Cork, Cork, Ireland
| | - John J O'Connor
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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