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Zhang L, Liu J, Liu M. Transsynaptic degeneration of ventral horn motor neurons exists but plays a minor role in lower motor system dysfunction in acute ischemic rats. PLoS One 2024; 19:e0298006. [PMID: 38669239 PMCID: PMC11051614 DOI: 10.1371/journal.pone.0298006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 01/16/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND As a leading cause of mortality and long-term disability, acute ischemic stroke can produce far-reaching pathophysiological consequences. Accumulating evidence has demonstrated abnormalities in the lower motor system following stroke, while the existence of Transsynaptic degeneration of contralateral spinal cord ventral horn (VH) neurons is still debated. METHODS Using a rat model of acute ischemic stroke, we analyzed spinal cord VH neuron counts contralaterally and ipsilaterally after stroke with immunofluorescence staining. Furthermore, we estimated the overall lower motor unit abnormalities after stroke by simultaneously measuring the modified neurological severity score (mNSS), compound muscle action potential (CMAP) amplitude, repetitive nerve stimulation (RNS), spinal cord VH neuron counts, and the corresponding muscle fiber morphology. The activation status of microglia and extracellular signal-regulated kinase 1/2 (ERK 1/2) in the spinal cord VH was also assessed. RESULTS At 7 days after stroke, the contralateral CMAP amplitudes declined to a nadir indicating lower motor function damage, and significant muscle disuse atrophy was observed on the same side; meanwhile, the VH neurons remained intact. At 14 days after focal stroke, lower motor function recovered with alleviated muscle disuse atrophy, while transsynaptic degeneration occurred on the contralateral side with elevated activation of ERK 1/2, along with the occurrence of neurogenic muscle atrophy. No apparent decrement of CMAP amplitude was observed with RNS during the whole experimental process. CONCLUSIONS This study offered an overview of changes in the lower motor system in experimental ischemic rats. We demonstrated that transsynaptic degeneration of contralateral VH neurons occurred when lower motor function significantly recovered, which indicated the minor role of transsynaptic degeneration in lower motor dysfunction during the acute and subacute phases of focal ischemic stroke.
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Affiliation(s)
- Lei Zhang
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Jingwen Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Mingsheng Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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2
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Koukalova L, Chmelova M, Amlerova Z, Vargova L. Out of the core: the impact of focal ischemia in regions beyond the penumbra. Front Cell Neurosci 2024; 18:1336886. [PMID: 38504666 PMCID: PMC10948541 DOI: 10.3389/fncel.2024.1336886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 02/08/2024] [Indexed: 03/21/2024] Open
Abstract
The changes in the necrotic core and the penumbra following induction of focal ischemia have been the focus of attention for some time. However, evidence shows, that ischemic injury is not confined to the primarily affected structures and may influence the remote areas as well. Yet many studies fail to probe into the structures beyond the penumbra, and possibly do not even find any significant results due to their short-term design, as secondary damage occurs later. This slower reaction can be perceived as a therapeutic opportunity, in contrast to the ischemic core defined as irreversibly damaged tissue, where the window for salvation is comparatively short. The pathologies in remote structures occur relatively frequently and are clearly linked to the post-stroke neurological outcome. In order to develop efficient therapies, a deeper understanding of what exactly happens in the exo-focal regions is necessary. The mechanisms of glia contribution to the ischemic damage in core/penumbra are relatively well described and include impaired ion homeostasis, excessive cell swelling, glutamate excitotoxic mechanism, release of pro-inflammatory cytokines and phagocytosis or damage propagation via astrocytic syncytia. However, little is known about glia involvement in post-ischemic processes in remote areas. In this literature review, we discuss the definitions of the terms "ischemic core", "penumbra" and "remote areas." Furthermore, we present evidence showing the array of structural and functional changes in the more remote regions from the primary site of focal ischemia, with a special focus on glia and the extracellular matrix. The collected information is compared with the processes commonly occurring in the ischemic core or in the penumbra. Moreover, the possible causes of this phenomenon and the approaches for investigation are described, and finally, we evaluate the efficacy of therapies, which have been studied for their anti-ischemic effect in remote areas in recent years.
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Affiliation(s)
- Ludmila Koukalova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Martina Chmelova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czechia
| | - Zuzana Amlerova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Lydia Vargova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czechia
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3
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Astrakas LG, Elbach S, Giannopulu I, Li S, Benjafield H, Tzika AA. The role of ventral tegmental area in chronic stroke rehabilitation: an exploratory study. Front Neurol 2023; 14:1270783. [PMID: 38116106 PMCID: PMC10728864 DOI: 10.3389/fneur.2023.1270783] [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: 08/02/2023] [Accepted: 11/15/2023] [Indexed: 12/21/2023] Open
Abstract
Introduction The acknowledged role of external rewards in chronic stroke rehabilitation, offering positive reinforcement and motivation, has significantly contributed to patient engagement and perseverance. However, the exploration of self-reward's importance in this context remains limited. This study aims to investigate the functional connectivity of the ventral tegmental area (VTA), a key node in the brain's reward circuitry, during motor task-based rehabilitation and its correlation with the recovery process. Methods Twelve right-handed healthy volunteers (4 men, 8 women, aged 57.4 ± 11.3 years) and twelve chronic stroke patients (5 men, 7 women, aged 48.1 ± 11.1 years) with clinically significant right-sided motor impairment (mean FM-UE score of 27.6 ± 8.7) participated. The analysis employed the CONN toolbox to assess the association between motor tasks and VTA connectivity using psychophysiological interaction (PPI). Results PPI analysis revealed motor-dependent changes in VTA connectivity, particularly with regions within the motor circuitry, cerebellum, and prefrontal cortex. Notably, stronger connectivity between the ipsilesional VTA and cerebellum was observed in healthy controls compared to chronic stroke patients, highlighting the importance of VTA-cerebellum interactions in motor function. Stroke patients' motor performance was associated with VTA modulation in areas related to both motor tasks and reward processing, emphasizing the role of self-reward processes in rehabilitation. Changes in VTA influence on motor circuitry were linked to improvements in motor performance resulting from rehabilitation. Discussion Our findings underscore the potential of neuroimaging techniques in quantifying and predicting rehabilitation outcomes by examining self-reward processes. The observed associations between VTA connectivity and motor performance in both healthy and stroke-affected individuals emphasize the role of psychological factors, particularly self-reward, in the rehabilitation process. This study contributes valuable insights into the intricate interplay between reward circuits and motor function, highlighting the importance of addressing psychological dimensions in neurorehabilitation strategies.
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Affiliation(s)
- Loukas G. Astrakas
- Medical Physics, Faculty of Medicine, University of Ioannina, Ioannina, Greece
| | - Sabrina Elbach
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | | | - Shasha Li
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Howard Benjafield
- School of Social Sciences and Professions – Psychology, London Metropolitan University, London, United Kingdom
| | - A. Aria Tzika
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
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Frase S, Steddin J, Paschen E, Lenz M, Conforti P, Haas CA, Vlachos A, Schachtrup C, Hosp JA. Dense dopaminergic innervation of the peri-infarct cortex despite dopaminergic cell loss after a pure motor-cortical stroke in rats. J Neurochem 2023; 167:427-440. [PMID: 37735852 DOI: 10.1111/jnc.15970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 08/28/2023] [Accepted: 09/12/2023] [Indexed: 09/23/2023]
Abstract
After ischemic stroke, the cortex directly adjacent to the ischemic core (i.e., the peri-infarct cortex, PIC) undergoes plastic changes that facilitate motor recovery. Dopaminergic signaling is thought to support this process. However, ischemic stroke also leads to the remote degeneration of dopaminergic midbrain neurons, possibly interfering with this beneficial effect. In this study, we assessed the reorganization of dopaminergic innervation of the PIC in a rat model of focal cortical stroke. Adult Sprague-Dawley rats either received a photothrombotic stroke (PTS) in the primary motor cortex (M1) or a sham operation. 30 days after PTS or sham procedure, the retrograde tracer Micro Ruby (MR) was injected into the PIC of stroke animals or into homotopic cortical areas of matched sham rats. Thus, dopaminergic midbrain neurons projecting into the PIC were identified based on MR signal and immunoreactivity against tyrosine hydroxylase (TH), a marker for dopaminergic neurons. The density of dopaminergic innervation within the PIC was assessed by quantification of dopaminergic boutons indicated by TH-immunoreactivity. Regarding postsynaptic processes, expression of dopamine receptors (D1- and D2) and a marker of the functional signal cascade (DARPP-32) were visualized histologically. Despite a 25% ipsilesional loss of dopaminergic midbrain neurons after PTS, the number and spatial distribution of dopaminergic neurons projecting to the PIC was not different compared to sham controls. Moreover, the density of dopaminergic innervation in the PIC was significantly higher than in homotopic cortical areas of the sham group. Within the PIC, D1-receptors were expressed in neurons, whereas D2-receptors were confined to astrocytes. The intensity of D1- and DARPP-32 expression appeared to be higher in the PIC compared to the contralesional homotopic cortex. Our data suggest a sprouting of dopaminergic fibers into the PIC and point to a role for dopaminergic signaling in reparative mechanisms post-stroke, potentially related to recovery.
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Affiliation(s)
- Sibylle Frase
- Department of Neurology and Neuroscience, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Julius Steddin
- Department of Neurology and Neuroscience, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Maximilian Lenz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Pasquale Conforti
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christian Schachtrup
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jonas A Hosp
- Department of Neurology and Neuroscience, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Lee K, Lee H, Kim YD, Nam HS, Lee HS, Yoo J, Cho S, Heo JH. Association of Substantia Nigra Degeneration with Poor Neurological Recovery in Basal Ganglia Infarctions. J Stroke 2023; 25:169-172. [PMID: 36470247 PMCID: PMC9911844 DOI: 10.5853/jos.2022.02145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/22/2022] [Accepted: 09/24/2022] [Indexed: 12/12/2022] Open
Affiliation(s)
- Kijeong Lee
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - HyungWoo Lee
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Young Dae Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
- Integrative Research Center for Cerebrovascular and Cardiovascular Diseases, Yonsei University College of Medicine, Seoul, Korea
| | - Hyo Suk Nam
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
- Integrative Research Center for Cerebrovascular and Cardiovascular Diseases, Yonsei University College of Medicine, Seoul, Korea
| | - Hye Sun Lee
- Biostatistics Collaboration Unit, Department of Research Affairs, Yonsei University College of Medicine, Seoul, Korea
| | - Joonsang Yoo
- Department of Neurology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea
| | - Sunghee Cho
- Burke Neurological Institute, White Plains, NY, USA
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Ji Hoe Heo
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
- Integrative Research Center for Cerebrovascular and Cardiovascular Diseases, Yonsei University College of Medicine, Seoul, Korea
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6
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Hosp JA, Dressing A, Engesser A, Glauche V, Kümmerer D, Vaidelyte EB, Musso M, Rijntjes M, Weiller C. The Role of Ascending Ventral-Tegmental Fibers for Recovery after Stroke. Ann Neurol 2022; 93:922-933. [PMID: 36585896 DOI: 10.1002/ana.26595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 12/29/2022] [Accepted: 12/30/2022] [Indexed: 01/01/2023]
Abstract
OBJECTIVES The integrity of cortical motor networks and their descending effector pathway (the corticospinal tract [CST]) is a major determinant motor recovery after stroke. However, this view neglects the importance of ascending tracts and their modulatory effects on cortical physiology. Here, we explore the role of such a tract that connects dopaminergic ventral tegmental midbrain nuclei to the motor cortex (the VTMC tract) for post-stroke recovery. METHODS Lesion data and diffusivity parameters (fractional anisotropy) of the ipsi- and contralesional VTMC tract and CST were obtained from 133 patients (63.9 ± 13.4 years, 45 women) during the acute and chronic stage after the first ever ischemic stroke in the middle cerebral artery territory. Degeneration of VTMC tract and CST was quantified and related to clinical outcome parameters (National Institute of Health Stroke Scale with motor and cortical symptom subscores; modified Fugl-Meyer upper extremity score; modified Ranking Scale [mRS]). RESULTS A significant post-stroke degeneration occurred in both tracts, but only VTMC degeneration was associated with lesion size. Using multiple regression models, we dissected the impact of particular tracts on recovery: Changes in VTMC tract integrity were stronger associated with independence in daily activities (mRS), upper limb motor impairment (modified Fugl-Meyer upper extremity score) and cortical symptoms (aphasia, neglect) captured by National Institute of Health Stroke Scale compared to CST. Changes in CST integrity merely were associated with the degree of hemiparesis (National Institute of Health Stroke Scale motor subscale). INTERPRETATION Post-stroke outcome is influenced by ascending (VTMC) and descending (CST) fiber tracts. Favorable outcome regarding independence (modified Ranking Scale), upper limb motor function (modified Fugl-Meyer upper extremity score), and cortical symptoms (aphasia, neglect) was more strongly related to the ascending than descending tract. ANN NEUROL 2023.
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Affiliation(s)
- Jonas A Hosp
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany
| | - Andrea Dressing
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anika Engesser
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany
| | - Volkmar Glauche
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dorothee Kümmerer
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ema B Vaidelyte
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany
| | - Mariachristina Musso
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michel Rijntjes
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Cornelius Weiller
- Department of Neurology and Clinical Neuroscience, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Freiburg Brain Imaging Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Frase S, Löffler F, Hosp JA. Enhancing Post-Stroke Rehabilitation and Preventing Exo-Focal Dopaminergic Degeneration in Rats-A Role for Substance P. Int J Mol Sci 2022; 23:ijms23073848. [PMID: 35409207 PMCID: PMC8999050 DOI: 10.3390/ijms23073848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 12/10/2022] Open
Abstract
Dopaminergic signaling is a prerequisite for motor learning. Delayed degeneration of dopaminergic neurons after stroke is linked to motor learning deficits impairing motor rehabilitation. This study investigates safety and efficacy of substance P (SP) treatment on post-stroke rehabilitation, as this neuropeptide combines neuroprotective and plasticity-promoting properties. Male Sprague Dawley rats received a photothrombotic stroke within the primary motor cortex (M1) after which a previously acquired skilled reaching task was rehabilitated. Rats were treated with intraperitoneal saline (control group, n = 7) or SP-injections (250 µg/kg) 30 min before (SP-pre; n = 7) or 16 h (SP-post; n = 6) after rehabilitation training. Dopaminergic neurodegeneration, microglial activation and substance P-immunoreactivity (IR) were analyzed immunohistochemically. Systemic SP significantly facilitated motor rehabilitation. This effect was more pronounced in SP-pre compared to SP-post animals. SP prevented dopaminergic cell loss after stroke, particularly in the SP-pre condition. Despite its proinflammatory propensity, SP administration did not increase stroke volumes, post-stroke deficits or activation of microglia in the midbrain. Finally, SP administration prevented ipsilesional hypertrophy of striatal SPergic innervation, particularly in the SP-post condition. Mechanistically, SP-pre likely involved plasticity-promoting effects in the early phase of rehabilitation, whereas preservation of dopaminergic signaling may have ameliorated rehabilitative success in both SP groups during later stages of training. Our results demonstrate the facilitating effect of SP treatment on motor rehabilitation after stroke, especially if administered prior to training. SP furthermore prevented delayed dopaminergic degeneration and preserved physiological endogenous SPergic innervation.
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Brown GC. Neuronal Loss after Stroke Due to Microglial Phagocytosis of Stressed Neurons. Int J Mol Sci 2021; 22:13442. [PMID: 34948237 PMCID: PMC8707068 DOI: 10.3390/ijms222413442] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/17/2022] Open
Abstract
After stroke, there is a rapid necrosis of all cells in the infarct, followed by a delayed loss of neurons both in brain areas surrounding the infarct, known as 'selective neuronal loss', and in brain areas remote from, but connected to, the infarct, known as 'secondary neurodegeneration'. Here we review evidence indicating that this delayed loss of neurons after stroke is mediated by the microglial phagocytosis of stressed neurons. After a stroke, neurons are stressed by ongoing ischemia, excitotoxicity and/or inflammation and are known to: (i) release "find-me" signals such as ATP, (ii) expose "eat-me" signals such as phosphatidylserine, and (iii) bind to opsonins, such as complement components C1q and C3b, inducing microglia to phagocytose such neurons. Blocking these factors on neurons, or their phagocytic receptors on microglia, can prevent delayed neuronal loss and behavioral deficits in rodent models of ischemic stroke. Phagocytic receptors on microglia may be attractive treatment targets to prevent delayed neuronal loss after stroke due to the microglial phagocytosis of stressed neurons.
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Affiliation(s)
- Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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CYP3A Excipient-Based Microemulsion Prolongs the Effect of Magnolol on Ischemia Stroke Rats. Pharmaceutics 2020; 12:pharmaceutics12080737. [PMID: 32764430 PMCID: PMC7464078 DOI: 10.3390/pharmaceutics12080737] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/29/2020] [Accepted: 08/04/2020] [Indexed: 12/14/2022] Open
Abstract
Magnolol, which is a CYP3A substrate, is a well-known agent that can facilitate neuroprotection and reduce ischemic brain damage. However, a well-controlled release formulation is needed for the effective delivery of magnolol due to its poor water solubility. In this study, we have developed a formulation for a CYP3A-excipient microemulsion, which can be administrated intraperitoneally to increase the solubility and bioavailability of magnolol and increase its neuroprotective effect against ischemic brain injury. The results showed a significant improvement in the area under the plotted curve of drug concentration versus time curve (AUC0–t) and mean residence time (MRT) of magnolol in microemulsion compared to when it was dissolved in dimethyl sulfoxide (DMSO). Both magnolol in DMSO and microemulsion, administrated after the onset of ischemia, showed a reduced visual brain infarct size. As such, this demonstrates a therapeutic effect on ischemic brain injury caused by occlusion, however it is important to note that a pharmacological effect cannot be concluded by this study. Ultimately, our study suggests that the excipient inhibitor-based microemulsion formulation could be a promising concept for the substrate drugs of CYP3A.
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