1
|
Hladky SB, Barrand MA. Alterations in brain fluid physiology during the early stages of development of ischaemic oedema. Fluids Barriers CNS 2024; 21:51. [PMID: 38858667 PMCID: PMC11163777 DOI: 10.1186/s12987-024-00534-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 03/22/2024] [Indexed: 06/12/2024] Open
Abstract
Oedema occurs when higher than normal amounts of solutes and water accumulate in tissues. In brain parenchymal tissue, vasogenic oedema arises from changes in blood-brain barrier permeability, e.g. in peritumoral oedema. Cytotoxic oedema arises from excess accumulation of solutes within cells, e.g. ischaemic oedema following stroke. This type of oedema is initiated when blood flow in the affected core region falls sufficiently to deprive brain cells of the ATP needed to maintain ion gradients. As a consequence, there is: depolarization of neurons; neural uptake of Na+ and Cl- and loss of K+; neuronal swelling; astrocytic uptake of Na+, K+ and anions; swelling of astrocytes; and reduction in ISF volume by fluid uptake into neurons and astrocytes. There is increased parenchymal solute content due to metabolic osmolyte production and solute influx from CSF and blood. The greatly increased [K+]isf triggers spreading depolarizations into the surrounding penumbra increasing metabolic load leading to increased size of the ischaemic core. Water enters the parenchyma primarily from blood, some passing into astrocyte endfeet via AQP4. In the medium term, e.g. after three hours, NaCl permeability and swelling rate increase with partial opening of tight junctions between blood-brain barrier endothelial cells and opening of SUR1-TPRM4 channels. Swelling is then driven by a Donnan-like effect. Longer term, there is gross failure of the blood-brain barrier. Oedema resolution is slower than its formation. Fluids without colloid, e.g. infused mock CSF, can be reabsorbed across the blood-brain barrier by a Starling-like mechanism whereas infused serum with its colloids must be removed by even slower extravascular means. Large scale oedema can increase intracranial pressure (ICP) sufficiently to cause fatal brain herniation. The potentially lethal increase in ICP can be avoided by craniectomy or by aspiration of the osmotically active infarcted region. However, the only satisfactory treatment resulting in retention of function is restoration of blood flow, providing this can be achieved relatively quickly. One important objective of current research is to find treatments that increase the time during which reperfusion is successful. Questions still to be resolved are discussed.
Collapse
Affiliation(s)
- Stephen B Hladky
- Department of Pharmacology, Tennis Court Rd., Cambridge, CB2 1PD, UK.
| | - Margery A Barrand
- Department of Pharmacology, Tennis Court Rd., Cambridge, CB2 1PD, UK
| |
Collapse
|
2
|
Hermanova Z, Valihrach L, Kriska J, Maheta M, Tureckova J, Kubista M, Anderova M. The deletion of AQP4 and TRPV4 affects astrocyte swelling/volume recovery in response to ischemia-mimicking pathologies. Front Cell Neurosci 2024; 18:1393751. [PMID: 38818517 PMCID: PMC11138210 DOI: 10.3389/fncel.2024.1393751] [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: 02/29/2024] [Accepted: 05/01/2024] [Indexed: 06/01/2024] Open
Abstract
Introduction Astrocytic Transient receptor potential vanilloid 4 (TRPV4) channels, together with Aquaporin 4 (AQP4), are suspected to be the key players in cellular volume regulation, and therefore may affect the development and severity of cerebral edema during ischemia. In this study, we examined astrocytic swelling/volume recovery in mice with TRPV4 and/or AQP4 deletion in response to in vitro ischemic conditions, to determine how the deletion of these channels can affect the development of cerebral edema. Methods We used three models of ischemia-related pathological conditions: hypoosmotic stress, hyperkalemia, and oxygenglucose deprivation (OGD), and observed their effect on astrocyte volume changes in acute brain slices of Aqp4-/-, Trpv4-/- and double knockouts. In addition, we employed single-cell RT-qPCR to assess the effect of TRPV4 and AQP4 deletion on the expression of other ion channels and transporters involved in the homeostatic functioning of astrocytes. Results Quantification of astrocyte volume changes during OGD revealed that the deletion of AQP4 reduces astrocyte swelling, while simultaneous deletion of both AQP4 and TRPV4 leads to a disruption of astrocyte volume recovery during the subsequent washout. Of note, astrocyte exposure to hypoosmotic stress or hyperkalemia revealed no differences in astrocyte swelling in the absence of AQP4, TRPV4, or both channels. Moreover, under ischemia-mimicking conditions, we identified two distinct subpopulations of astrocytes with low and high volumetric responses (LRA and HRA), and their analyses revealed that mainly HRA are affected by the deletion of AQP4, TRPV4, or both channels. Furthermore, gene expression analysis revealed reduced expression of the ion transporters KCC1 and ClC2 as well as the receptors GABAB and NMDA in Trpv4-/- mice. The deletion of AQP4 instead caused reduced expression of the serine/cysteine peptidase inhibitor Serpina3n. Discussion Thus, we showed that in AQP4 or TRPV4 knockouts, not only the specific function of these channels is affected, but also the expression of other proteins, which may modulate the ischemic cascade and thus influence the final impact of ischemia.
Collapse
Affiliation(s)
- Zuzana Hermanova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Lukas Valihrach
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
- Laboratory of Gene Expression, Institute of Biotechnology CAS, Vestec, Czechia
| | - Jan Kriska
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
| | - Mansi Maheta
- Laboratory of Gene Expression, Institute of Biotechnology CAS, Vestec, Czechia
| | - Jana Tureckova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
| | - Mikael Kubista
- Laboratory of Gene Expression, Institute of Biotechnology CAS, Vestec, Czechia
| | - Miroslava Anderova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
| |
Collapse
|
3
|
Yang MF, Ren DX, Pan X, Li CX, Xu SY. The Role of Astrocytes in Migraine with Cortical Spreading Depression: Protagonists or Bystanders? A Narrative Review. Pain Ther 2024:10.1007/s40122-024-00610-9. [PMID: 38743247 DOI: 10.1007/s40122-024-00610-9] [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: 03/24/2024] [Accepted: 05/01/2024] [Indexed: 05/16/2024] Open
Abstract
Cortical spreading depression (CSD) is a slow wave of cortical depolarization closely associated with migraines with an aura. Previously, it was thought that CSD depolarization was mainly driven by neurons, with characteristic changes in neuronal swelling and increased extracellular potassium (K+) and glutamate. However, the role of astrocytes, a member of the neurovascular unit, in migraine with CSD has recently received increasing attention. In the early stages of CSD, astrocytes provide neurons with energy support and clear K+ and glutamate from synaptic gaps. However, in the late stages of CSD, astrocytes release large amounts of lactic acid to exacerbate hypoxia when the energy demand exceeds the astrocytes' compensatory capacity. Astrocyte endfoot swelling is a characteristic of CSD, and neurons are not similarly altered. It is primarily due to K+ influx and abnormally active calcium (Ca2+) signaling. Aquaporin 4 (AQP-4) only mediates K+ influx and has little role as an aquaporin. Astrocytes endfoot swelling causes perivascular space closure, slowing the glymphatic system flow and exacerbating neuroinflammation, leading to persistent CSD. Astrocytes are double-edged swords in migraine with CSD and may be potential targets for CSD interventions.
Collapse
Affiliation(s)
- Meng-Fan Yang
- Department of Neurology, Headache Center, The First Hospital of Shanxi Medical University, Jiefangnan 85 Road, Taiyuan,, 030001, Shanxi, China
| | - Dong-Xue Ren
- Department of Neurology, Headache Center, The First Hospital of Shanxi Medical University, Jiefangnan 85 Road, Taiyuan,, 030001, Shanxi, China
| | - Xue Pan
- Department of Neurology, Headache Center, The First Hospital of Shanxi Medical University, Jiefangnan 85 Road, Taiyuan,, 030001, Shanxi, China
| | - Chang-Xin Li
- Department of Neurology, Headache Center, The First Hospital of Shanxi Medical University, Jiefangnan 85 Road, Taiyuan,, 030001, Shanxi, China
| | - Sui-Yi Xu
- Department of Neurology, Headache Center, The First Hospital of Shanxi Medical University, Jiefangnan 85 Road, Taiyuan,, 030001, Shanxi, China.
- Research Center for Neurological Diseases, Center for Cerebrovascular Diseases Research, Shanxi Medical University, Taiyuan, China.
| |
Collapse
|
4
|
Wu CH, Chang FC, Wang YF, Lirng JF, Wu HM, Pan LLH, Wang SJ, Chen SP. Impaired Glymphatic and Meningeal Lymphatic Functions in Patients with Chronic Migraine. Ann Neurol 2024; 95:583-595. [PMID: 38055324 DOI: 10.1002/ana.26842] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/13/2023] [Accepted: 11/27/2023] [Indexed: 12/07/2023]
Abstract
OBJECTIVE This study was undertaken to investigate migraine glymphatic and meningeal lymphatic vessel (mLV) functions. METHODS Migraine patients and healthy controls (HCs) were prospectively recruited between 2020 and 2023. Diffusion tensor image analysis along the perivascular space (DTI-ALPS) index for glymphatics and dynamic contrast-enhanced magnetic resonance imaging parameters (time to peak [TTP]/enhancement integral [EI]/mean time to enhance [MTE]) for para-superior sagittal (paraSSS)-mLV or paratransverse sinus (paraTS)-mLV in episodic migraine (EM), chronic migraine (CM), and CM with and without medication-overuse headache (MOH) were analyzed. DTI-ALPS correlations with clinical parameters (migraine severity [numeric rating scale]/disability [Migraine Disability Assessment (MIDAS)]/bodily pain [Widespread Pain Index]/sleep quality [Pittsburgh Sleep Quality Index (PSQI)]) were examined. RESULTS In total, 175 subjects (112 migraine + 63 HCs) were investigated. DTI-ALPS values were lower in CM (median [interquartile range] = 0.64 [0.12]) than in EM (0.71 [0.13], p = 0.005) and HCs (0.71 [0.09], p = 0.004). CM with MOH (0.63 [0.07]) had lower DTI-ALPS values than CM without MOH (0.73 [0.12], p < 0.001). Furthermore, CM had longer TTP (paraSSS-mLV: 55.8 [12.9] vs 40.0 [7.6], p < 0.001; paraTS-mLV: 51.2 [8.1] vs 44.0 [3.3], p = 0.002), EI (paraSSS-mLV: 45.5 [42.0] vs 16.1 [9.2], p < 0.001), and MTE (paraSSS-mLV: 253.7 [6.7] vs 248.4 [13.8], p < 0.001; paraTS-mLV: 252.0 [6.2] vs 249.7 [1.2], p < 0.001) than EM patients. The MIDAS (p = 0.002) and PSQI (p = 0.002) were negatively correlated with DTI-ALPS index after Bonferroni corrections (p < q = 0.01). INTERPRETATION CM patients, particularly those with MOH, have glymphatic and meningeal lymphatic dysfunctions, which are highly clinically relevant and may implicate pathogenesis for migraine chronification. ANN NEUROL 2024;95:583-595.
Collapse
Grants
- MOHW 108-TDU-B-211-133001 Ministry of Health and Welfare, Taiwan
- MOHW107-TDU-B-211-123001 Ministry of Health and Welfare, Taiwan
- MOHW112-TDU-B-211-144001 Ministry of Health and Welfare, Taiwan
- N/A Professor Tsuen CHANG's Scholarship Program from Medical Scholarship Foundation In Memory Of Professor Albert Ly-Young Shen
- V109B-009 Taipei Veterans General Hospital
- V110C-102 Taipei Veterans General Hospital
- V111B-032 Taipei Veterans General Hospital
- V112B-007 Taipei Veterans General Hospital
- V112C-053 Taipei Veterans General Hospital
- V112C-059 Taipei Veterans General Hospital
- V112C-113 Taipei Veterans General Hospital
- V112D67-001-MY3-1 Taipei Veterans General Hospital
- V112D67-002-MY3-1 Taipei Veterans General Hospital
- V112E-004-1 Taipei Veterans General Hospital
- VGH-111-C-158 Taipei Veterans General Hospital
- The Brain Research Center, National Yang Ming Chiao Tung University from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan
- 110-2314-B-075-005 The National Science and Technology Council, Taiwan
- 110-2314-B-075-032 The National Science and Technology Council, Taiwan
- 110-2321-B-010-005- The National Science and Technology Council, Taiwan
- 110-2326-B-A49A-501-MY3 The National Science and Technology Council, Taiwan
- 111-2314-B-075 -086-MY3 The National Science and Technology Council, Taiwan
- 111-2314-B-075-025 -MY3 The National Science and Technology Council, Taiwan
- 111-2314-B-A49-069-MY3 The National Science and Technology Council, Taiwan
- 111-2321-B-A49-004 The National Science and Technology Council, Taiwan
- 111-2321-B-A49-011 The National Science and Technology Council, Taiwan
- 112-2314-B-075-066- The National Science and Technology Council, Taiwan
- 112-2314-B-A49-037 -MY3 The National Science and Technology Council, Taiwan
- 112-2321-B-075-007 The National Science and Technology Council, Taiwan
- NSTC 108-2314-B-010-022 -MY3 The National Science and Technology Council, Taiwan
- 109V1-5-2 Veterans General Hospitals and University System of Taiwan Joint Research Program
- 110-G1-5-2 Veterans General Hospitals and University System of Taiwan Joint Research Program
- VGHUST-112-G1-2-1 Veterans General Hospitals and University System of Taiwan Joint Research Program
- Vivian W. Yen Neurological Foundation
- CI-109-3 Yen Tjing Ling Medical Foundation
- CI-111-2 Yen Tjing Ling Medical Foundation
- CI-112-2 Yen Tjing Ling Medical Foundation
Collapse
Affiliation(s)
- Chia-Hung Wu
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Feng-Chi Chang
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yen-Feng Wang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Jiing-Feng Lirng
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Hsiu-Mei Wu
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Li-Ling Hope Pan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Shuu-Jiun Wang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Shih-Pin Chen
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Division of Translational Research, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan
| |
Collapse
|
5
|
Blaeser AS, Zhao J, Sugden AU, Carneiro-Nascimento S, Andermann ML, Levy D. Sensitization of meningeal afferents to locomotion-related meningeal deformations in a migraine model. eLife 2024; 12:RP91871. [PMID: 38329894 PMCID: PMC10942541 DOI: 10.7554/elife.91871] [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] [Indexed: 02/10/2024] Open
Abstract
Migraine headache is hypothesized to involve the activation and sensitization of trigeminal sensory afferents that innervate the cranial meninges. To better understand migraine pathophysiology and improve clinical translation, we used two-photon calcium imaging via a closed cranial window in awake mice to investigate changes in the responses of meningeal afferent fibers using a preclinical model of migraine involving cortical spreading depolarization (CSD). A single CSD episode caused a seconds-long wave of calcium activation that propagated across afferents and along the length of individual afferents. Surprisingly, unlike previous studies in anesthetized animals with exposed meninges, only a very small afferent population was persistently activated in our awake mouse preparation, questioning the relevance of this neuronal response to the onset of migraine pain. In contrast, we identified a larger subset of meningeal afferents that developed augmented responses to acute three-dimensional meningeal deformations that occur in response to locomotion bouts. We observed increased responsiveness in a subset of afferents that were already somewhat sensitive to meningeal deformation before CSD. Furthermore, another subset of previously insensitive afferents also became sensitive to meningeal deformation following CSD. Our data provides new insights into the mechanisms underlying migraine, including the emergence of enhanced meningeal afferent responses to movement-related meningeal deformations as a potential neural substrate underlying the worsening of migraine headache during physical activity.
Collapse
Affiliation(s)
- Andrew S Blaeser
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
| | - Jun Zhao
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
| | - Arthur U Sugden
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
| | - Simone Carneiro-Nascimento
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
| | - Mark L Andermann
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Dan Levy
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
| |
Collapse
|
6
|
Blaeser AS, Zhao J, Sugden AU, Carneiro-Nascimento S, Andermann ML, Levy D. Sensitization of meningeal afferents to locomotion-related meningeal deformations in a migraine model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.549838. [PMID: 37577675 PMCID: PMC10418100 DOI: 10.1101/2023.07.31.549838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Migraine headache is hypothesized to involve the activation and sensitization of trigeminal sensory afferents that innervate the cranial meninges. To better understand migraine pathophysiology and improve clinical translation, we used two-photon calcium imaging via a closed cranial window in awake mice to investigate changes in the responses of meningeal afferent fibers using a preclinical model of migraine involving cortical spreading depolarization (CSD). A single CSD episode caused a seconds-long wave of calcium activation that propagated across afferents and along the length of individual afferents. Surprisingly, unlike previous studies in anesthetized animals with exposed meninges, only a very small afferent population was persistently activated in our awake mouse preparation, questioning the relevance of this neuronal response to the onset of migraine pain. In contrast, we identified a larger subset of meningeal afferents that developed augmented responses to acute three-dimensional meningeal deformations that occur in response to locomotion bouts. We observed increased responsiveness in a subset of afferents that were already somewhat sensitive to meningeal deformation before CSD. Furthermore, another subset of previously insensitive afferents also became sensitive to meningeal deformation following CSD. Our data provides new insights into the mechanisms underlying migraine, including the emergence of enhanced meningeal afferent responses to movement-related meningeal deformations as a potential neural substrate underlying the worsening of migraine headache during physical activity.
Collapse
Affiliation(s)
- Andrew S Blaeser
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Jun Zhao
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Arthur U Sugden
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Simone Carneiro-Nascimento
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Mark L Andermann
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Dan Levy
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| |
Collapse
|
7
|
Dong X, Zhao D. Ferulic acid as a therapeutic agent in depression: Evidence from preclinical studies. CNS Neurosci Ther 2023. [PMID: 37183361 PMCID: PMC10401106 DOI: 10.1111/cns.14265] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 04/17/2023] [Accepted: 05/03/2023] [Indexed: 05/16/2023] Open
Abstract
Depression is a common but severe mood disorder with a very high prevalence across the general population. Depression is of global concern and poses a threat to human physical and mental health. Ferulic acid (FA) is a natural active ingredient that has antioxidative, anti-inflammatory, and free radical scavenging properties. Furthermore, studies have shown that FA can exert antidepressant effects through a variety of mechanisms. The aim of the review was to comprehensively elucidate the mechanisms in FA that alleviate depression using animal models. The in vivo (animal) studies on the mechanism of FA treatment of depression were searched in PubMed, Chinese National Knowledge Infrastructure, Baidu academic, and Wan fang databases. Thereafter, the literature conclusions were summarized accordingly. Ferulic acid was found to significantly improve the depressive-like behaviors of animal models, suggesting that FA is a potential natural product in the treatment of depression. The mechanisms are achieved by enhancing monoamine oxidase A (MOA) activity, inhibiting microglia activation and inflammatory factor release, anti-oxidative stress, promoting hippocampal nerve regeneration, increasing brain-derived neurotrophic factor secretion, regulating gut microbiome, and activating protein kinase B/collapsin response mediator protein 2 (AKT/CRMP2) signaling pathway. Ferulic acid produces significant antidepressant effects in animal depression models through various mechanisms, suggesting its potential value as a treatment of depression. However, clinical research trials involving FA are required further to provide a solid foundation for its clinical application.
Collapse
Affiliation(s)
- Xiaoyu Dong
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
| | - Dongxue Zhao
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, China
| |
Collapse
|
8
|
Li X, Helleringer R, Martucci LL, Dallérac G, Cancela JM, Galante M. Low Temperature Delays the Effects of Ischemia in Bergmann Glia and in Cerebellar Tissue Swelling. Biomedicines 2023; 11:biomedicines11051363. [PMID: 37239034 DOI: 10.3390/biomedicines11051363] [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: 03/27/2023] [Revised: 04/23/2023] [Accepted: 04/29/2023] [Indexed: 05/28/2023] Open
Abstract
Cerebral ischemia results in oxygen and glucose deprivation that most commonly occurs after a reduction or interruption in the blood supply to the brain. The consequences of cerebral ischemia are complex and involve the loss of metabolic ATP, excessive K+ and glutamate accumulation in the extracellular space, electrolyte imbalance, and brain edema formation. So far, several treatments have been proposed to alleviate ischemic damage, yet few are effective. Here, we focused on the neuroprotective role of lowering the temperature in ischemia mimicked by an episode of oxygen and glucose deprivation (OGD) in mouse cerebellar slices. Our results suggest that lowering the temperature of the extracellular 'milieu' delays both the increases in [K+]e and tissue swelling, two dreaded consequences of cerebellar ischemia. Moreover, radial glial cells (Bergmann glia) display morphological changes and membrane depolarizations that are markedly impeded by lowering the temperature. Overall, in this model of cerebellar ischemia, hypothermia reduces the deleterious homeostatic changes regulated by Bergmann glia.
Collapse
Affiliation(s)
- Xia Li
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, 91400 Saclay, France
| | - Romain Helleringer
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, 91400 Saclay, France
| | - Lora L Martucci
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, 91400 Saclay, France
| | - Glenn Dallérac
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, 91400 Saclay, France
| | - José-Manuel Cancela
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, 91400 Saclay, France
| | - Micaela Galante
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, 91400 Saclay, France
| |
Collapse
|
9
|
Peng S, Liu J, Liang C, Yang L, Wang G. Aquaporin-4 in glymphatic system, and its implication for central nervous system disorders. Neurobiol Dis 2023; 179:106035. [PMID: 36796590 DOI: 10.1016/j.nbd.2023.106035] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 02/06/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023] Open
Abstract
The clearance function is essential for maintaining brain tissue homeostasis, and the glymphatic system is the main pathway for removing brain interstitial solutes. Aquaporin-4 (AQP4) is the most abundantly expressed aquaporin in the central nervous system (CNS) and is an integral component of the glymphatic system. In recent years, many studies have shown that AQP4 affects the morbidity and recovery process of CNS disorders through the glymphatic system, and AQP4 shows notable variability in CNS disorders and is part of the pathogenesis of these diseases. Therefore, there has been considerable interest in AQP4 as a potential and promising target for regulating and improving neurological impairment. This review aims to summarize the pathophysiological role that AQP4 plays in several CNS disorders by affecting the clearance function of the glymphatic system. The findings can contribute to a better understanding of the self-regulatory functions in CNS disorders that AQP4 were involved in and provide new therapeutic alternatives for incurable debilitating neurodegenerative disorders of CNS in the future.
Collapse
Affiliation(s)
- Shasha Peng
- 56 Xinjian southern St, Department of Pharmacology, School of Basical Medical Sciences, Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Jiachen Liu
- 172 Tongzipo Rd, Xiangya Medical College of Central South University, Changsha, Hunan 410013, China
| | - Chuntian Liang
- 56 Xinjian southern St, Department of Neurology, Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Lijun Yang
- 56 Xinjian southern St, Department of Pharmacology, School of Basical Medical Sciences, Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Gaiqing Wang
- 56 Xinjian southern St, Department of Neurology, Shanxi Medical University, Taiyuan, Shanxi 030001, China; 146 JieFang forth Rd, Department of Neurology, SanYa Central Hospital (Hainan Third People's Hospital), Hainan Medical University, SanYa, Hainan 572000, China.
| |
Collapse
|
10
|
Koch T, Vinje V, Mardal KA. Estimates of the permeability of extra-cellular pathways through the astrocyte endfoot sheath. Fluids Barriers CNS 2023; 20:20. [PMID: 36941607 PMCID: PMC10026447 DOI: 10.1186/s12987-023-00421-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/07/2023] [Indexed: 03/23/2023] Open
Abstract
BACKGROUND Astrocyte endfoot processes are believed to cover all micro-vessels in the brain cortex and may play a significant role in fluid and substance transport into and out of the brain parenchyma. Detailed fluid mechanical models of diffusive and advective transport in the brain are promising tools to investigate theories of transport. METHODS We derive theoretical estimates of astrocyte endfoot sheath permeability for advective and diffusive transport and its variation in microvascular networks from mouse brain cortex. The networks are based on recently published experimental data and generated endfoot patterns are based on Voronoi tessellations of the perivascular surface. We estimate corrections for projection errors in previously published data. RESULTS We provide structural-functional relationships between vessel radius and resistance that can be directly used in flow and transport simulations. We estimate endfoot sheath filtration coefficients in the range [Formula: see text] to [Formula: see text], diffusion membrane coefficients for small solutes in the range [Formula: see text] to [Formula: see text], and gap area fractions in the range 0.2-0.6%, based on a inter-endfoot gap width of 20 nm. CONCLUSIONS The astrocyte endfoot sheath surrounding microvessels forms a secondary barrier to extra-cellular transport, separating the extra-cellular space of the parenchyma and the perivascular space outside the endothelial layer. The filtration and membrane diffusion coefficients of the endfoot sheath are estimated to be an order of magnitude lower than those of the extra-cellular matrix while being two orders of magnitude higher than those of the vessel wall.
Collapse
Affiliation(s)
- Timo Koch
- Department of Mathematics, University of Oslo, Postboks 1053 Blindern, 0316, Oslo, Norway.
- Simula Research Laboratory, Kristian Augusts gate 23, 0164, Oslo, Norway.
| | - Vegard Vinje
- Simula Research Laboratory, Kristian Augusts gate 23, 0164, Oslo, Norway
| | - Kent-André Mardal
- Department of Mathematics, University of Oslo, Postboks 1053 Blindern, 0316, Oslo, Norway
- Simula Research Laboratory, Kristian Augusts gate 23, 0164, Oslo, Norway
| |
Collapse
|
11
|
Lee DA, Lee H, Park KM. Normal glymphatic system function in patients with migraine: A pilot study. Headache 2022; 62:718-725. [DOI: 10.1111/head.14320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/07/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Dong Ah Lee
- Department of Neurology Haeundae Paik Hospital Inje University College of Medicine Busan Korea
| | - Ho‐Joon Lee
- Department of Radiology Haeundae Paik Hospital Inje University College of Medicine Busan Korea
| | - Kang Min Park
- Department of Neurology Haeundae Paik Hospital Inje University College of Medicine Busan Korea
| |
Collapse
|
12
|
Yi T, Gao P, Zhu T, Yin H, Jin S. Glymphatic System Dysfunction: A Novel Mediator of Sleep Disorders and Headaches. Front Neurol 2022; 13:885020. [PMID: 35665055 PMCID: PMC9160458 DOI: 10.3389/fneur.2022.885020] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 04/13/2022] [Indexed: 11/13/2022] Open
Abstract
Sleep contributes to the maintenance of overall health and well-being. There are a growing number of patients who have headache disorders that are significantly affected by poor sleep. This is a paradoxical relationship, whereby sleep deprivation or excess sleep leads to a worsening of headaches, yet sleep onset also alleviates ongoing headache pain. Currently, the mechanism of action remains controversial and poorly understood. The glymphatic system is a newly discovered perivascular network that encompasses the whole brain and is responsible for removing toxic proteins and waste metabolites from the brain as well as replenishing nutrition and energy. Recent studies have suggested that glymphatic dysfunction is a common underlying etiology of sleep disorders and headache pain. This study reviews the current literature on the relationship between the glymphatic system, sleep, and headaches, discusses their roles, and proposes acupuncture as a non-invasive way to focus on the glymphatic function to improve sleep quality and alleviate headache pain.
Collapse
Affiliation(s)
- Ting Yi
- Rehabilitation and Health Preservation School, Chengdu University of TCM, Chengdu, China
| | - Ping Gao
- Rehabilitation and Health Preservation School, Chengdu University of TCM, Chengdu, China
| | - Tianmin Zhu
- Rehabilitation and Health Preservation School, Chengdu University of TCM, Chengdu, China
- Tianmin Zhu
| | - Haiyan Yin
- School of Acupuncture and Tuina, Chengdu University of TCM, Chengdu, China
- *Correspondence: Haiyan Yin
| | - Shuoguo Jin
- Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Shuoguo Jin
| |
Collapse
|
13
|
Validating a Computational Framework for Ionic Electrodiffusion with Cortical Spreading Depression as a Case Study. eNeuro 2022; 9:ENEURO.0408-21.2022. [PMID: 35365505 PMCID: PMC9045477 DOI: 10.1523/eneuro.0408-21.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 02/21/2022] [Accepted: 03/12/2022] [Indexed: 11/21/2022] Open
Abstract
Cortical spreading depression (CSD) is a wave of pronounced depolarization of brain tissue accompanied by substantial shifts in ionic concentrations and cellular swelling. Here, we validate a computational framework for modeling electrical potentials, ionic movement, and cellular swelling in brain tissue during CSD. We consider different model variations representing wild-type (WT) or knock-out/knock-down mice and systematically compare the numerical results with reports from a selection of experimental studies. We find that the data for several CSD hallmarks obtained computationally, including wave propagation speed, direct current shift duration, peak in extracellular K+ concentration as well as a pronounced shrinkage of extracellular space (ECS) are well in line with what has previously been observed experimentally. Further, we assess how key model parameters including cellular diffusivity, structural ratios, membrane water and/or K+ permeabilities affect the set of CSD characteristics.
Collapse
|
14
|
Szczygielski J, Kopańska M, Wysocka A, Oertel J. Cerebral Microcirculation, Perivascular Unit, and Glymphatic System: Role of Aquaporin-4 as the Gatekeeper for Water Homeostasis. Front Neurol 2021; 12:767470. [PMID: 34966347 PMCID: PMC8710539 DOI: 10.3389/fneur.2021.767470] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/12/2021] [Indexed: 12/13/2022] Open
Abstract
In the past, water homeostasis of the brain was understood as a certain quantitative equilibrium of water content between intravascular, interstitial, and intracellular spaces governed mostly by hydrostatic effects i.e., strictly by physical laws. The recent achievements in molecular bioscience have led to substantial changes in this regard. Some new concepts elaborate the idea that all compartments involved in cerebral fluid homeostasis create a functional continuum with an active and precise regulation of fluid exchange between them rather than only serving as separate fluid receptacles with mere passive diffusion mechanisms, based on hydrostatic pressure. According to these concepts, aquaporin-4 (AQP4) plays the central role in cerebral fluid homeostasis, acting as a water channel protein. The AQP4 not only enables water permeability through the blood-brain barrier but also regulates water exchange between perivascular spaces and the rest of the glymphatic system, described as pan-cerebral fluid pathway interlacing macroscopic cerebrospinal fluid (CSF) spaces with the interstitial fluid of brain tissue. With regards to this, AQP4 makes water shift strongly dependent on active processes including changes in cerebral microcirculation and autoregulation of brain vessels capacity. In this paper, the role of the AQP4 as the gatekeeper, regulating the water exchange between intracellular space, glymphatic system (including the so-called neurovascular units), and intravascular compartment is reviewed. In addition, the new concepts of brain edema as a misbalance in water homeostasis are critically appraised based on the newly described role of AQP4 for fluid permeation. Finally, the relevance of these hypotheses for clinical conditions (including brain trauma and stroke) and for both new and old therapy concepts are analyzed.
Collapse
Affiliation(s)
- Jacek Szczygielski
- Department of Neurosurgery, Institute of Medical Sciences, University of Rzeszów, Rzeszów, Poland.,Department of Neurosurgery, Faculty of Medicine and Saarland University Medical Center, Saarland University, Homburg, Germany
| | - Marta Kopańska
- Department of Pathophysiology, Institute of Medical Sciences, University of Rzeszów, Rzeszów, Poland
| | - Anna Wysocka
- Chair of Internal Medicine and Department of Internal Medicine in Nursing, Faculty of Health Sciences, Medical University of Lublin, Lublin, Poland
| | - Joachim Oertel
- Department of Neurosurgery, Faculty of Medicine and Saarland University Medical Center, Saarland University, Homburg, Germany
| |
Collapse
|
15
|
Abstract
Our brains consist of 80% water, which is continuously shifted between different compartments and cell types during physiological and pathophysiological processes. Disturbances in brain water homeostasis occur with pathologies such as brain oedema and hydrocephalus, in which fluid accumulation leads to elevated intracranial pressure. Targeted pharmacological treatments do not exist for these conditions owing to our incomplete understanding of the molecular mechanisms governing brain water transport. Historically, the transmembrane movement of brain water was assumed to occur as passive movement of water along the osmotic gradient, greatly accelerated by water channels termed aquaporins. Although aquaporins govern the majority of fluid handling in the kidney, they do not suffice to explain the overall brain water movement: either they are not present in the membranes across which water flows or they appear not to be required for the observed flow of water. Notably, brain fluid can be secreted against an osmotic gradient, suggesting that conventional osmotic water flow may not describe all transmembrane fluid transport in the brain. The cotransport of water is an unconventional molecular mechanism that is introduced in this Review as a missing link to bridge the gap in our understanding of cellular and barrier brain water transport.
Collapse
Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| |
Collapse
|
16
|
Belmaati Cherkaoui M, Vacca O, Izabelle C, Boulay AC, Boulogne C, Gillet C, Barnier JV, Rendon A, Cohen-Salmon M, Vaillend C. Dp71 contribution to the molecular scaffold anchoring aquaporine-4 channels in brain macroglial cells. Glia 2020; 69:954-970. [PMID: 33247858 DOI: 10.1002/glia.23941] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 11/13/2020] [Accepted: 11/17/2020] [Indexed: 02/06/2023]
Abstract
Intellectual disability in Duchenne muscular dystrophy has been associated with the loss of dystrophin-protein 71, Dp71, the main dystrophin-gene product in the adult brain. Dp71 shows major expression in perivascular macroglial endfeet, suggesting that dysfunctional glial mechanisms contribute to cognitive impairments. In the present study, we investigated the molecular alterations induced by a selective loss of Dp71 in mice, using semi-quantitative immunogold analyses in electron microscopy and immunofluorescence confocal analyses in brain sections and purified gliovascular units. In macroglial pericapillary endfeet of the cerebellum and hippocampus, we found a drastic reduction (70%) of the polarized distribution of aquaporin-4 (AQP4) channels, a 50% reduction of β-dystroglycan, and a complete loss of α1-syntrophin. Interestingly, in the hippocampus and cortex, these effects were not homogeneous: AQP4 and AQP4ex isoforms were mostly lost around capillaries but preserved in large vessels corresponding to pial arteries, penetrating cortical arterioles, and arterioles of the hippocampal fissure, indicating the presence of Dp71-independent pools of AQP4 in these vascular structures. In conclusion, the depletion of Dp71 strongly alters the distribution of AQP4 selectively in macroglial perivascular endfeet surrounding capillaries. This effect likely affects water homeostasis and blood-brain barrier functions and may thus contribute to the synaptic and cognitive defects associated with Dp71 deficiency.
Collapse
Affiliation(s)
| | - Ophélie Vacca
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| | - Charlotte Izabelle
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| | - Anne-Cécile Boulay
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Unité Mixte de Recherche 7241CNRS, Unité 1050 INSERM, PSL Research University, Paris, France
| | - Claire Boulogne
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Cynthia Gillet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Jean-Vianney Barnier
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| | - Alvaro Rendon
- UPMC Université Paris 06, INSERM, CNRS, Institut de la Vision, Sorbonne Universités, Paris, France
| | - Martine Cohen-Salmon
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Unité Mixte de Recherche 7241CNRS, Unité 1050 INSERM, PSL Research University, Paris, France
| | - Cyrille Vaillend
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| |
Collapse
|
17
|
Toft-Bertelsen TL, Larsen BR, Christensen SK, Khandelia H, Waagepetersen HS, MacAulay N. Clearance of activity-evoked K + transients and associated glia cell swelling occur independently of AQP4: A study with an isoform-selective AQP4 inhibitor. Glia 2020; 69:28-41. [PMID: 32506554 DOI: 10.1002/glia.23851] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/29/2022]
Abstract
The mammalian brain consists of 80% water, which is continuously shifted between different compartments and cellular structures by mechanisms that are, to a large extent, unresolved. Aquaporin 4 (AQP4) is abundantly expressed in glia and ependymal cells of the mammalian brain and has been proposed to act as a gatekeeper for brain water dynamics, predominantly based on studies utilizing AQP4-deficient mice. However, these mice have a range of secondary effects due to the gene deletion. An efficient and selective AQP4 inhibitor has thus been sorely needed to validate the results obtained in the AQP4-/- mice to quantify the contribution of AQP4 to brain fluid dynamics. In AQP4-expressing Xenopus laevis oocytes monitored by a high-resolution volume recording system, we here demonstrate that the compound TGN-020 is such a selective AQP4 inhibitor. TGN-020 targets the tested species of AQP4 with an IC50 of ~3.5 μM, but displays no inhibitory effect on the other AQPs (AQP1-AQP9). With this tool, we employed rat hippocampal slices and ion-sensitive microelectrodes to determine the role of AQP4 in glia cell swelling following neuronal activity. TGN-020-mediated inhibition of AQP4 did not prevent stimulus-induced extracellular space shrinkage, nor did it slow clearance of the activity-evoked K+ transient. These data, obtained with a verified isoform-selective AQP4 inhibitor, indicate that AQP4 is not required for the astrocytic contribution to the K+ clearance or the associated extracellular space shrinkage.
Collapse
Affiliation(s)
- Trine Lisberg Toft-Bertelsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Brian Roland Larsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sofie Kjellerup Christensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Himanshu Khandelia
- Department of Physics, Chemistry and Pharmacy, Faculty of Science, University of Southern Denmark, Odense, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
18
|
MacAulay N. Molecular mechanisms of K + clearance and extracellular space shrinkage-Glia cells as the stars. Glia 2020; 68:2192-2211. [PMID: 32181522 DOI: 10.1002/glia.23824] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/28/2020] [Accepted: 03/04/2020] [Indexed: 12/17/2022]
Abstract
Neuronal signaling in the central nervous system (CNS) associates with release of K+ into the extracellular space resulting in transient increases in [K+ ]o . This elevated K+ is swiftly removed, in part, via uptake by neighboring glia cells. This process occurs in parallel to the [K+ ]o elevation and glia cells thus act as K+ sinks during the neuronal activity, while releasing it at the termination of the pulse. The molecular transport mechanisms governing this glial K+ absorption remain a point of debate. Passive distribution of K+ via Kir4.1-mediated spatial buffering of K+ has become a favorite within the glial field, although evidence for a quantitatively significant contribution from this ion channel to K+ clearance from the extracellular space is sparse. The Na+ /K+ -ATPase, but not the Na+ /K+ /Cl- cotransporter, NKCC1, shapes the activity-evoked K+ transient. The different isoform combinations of the Na+ /K+ -ATPase expressed in glia cells and neurons display different kinetic characteristics and are thereby distinctly geared toward their temporal and quantitative contribution to K+ clearance. The glia cell swelling occurring with the K+ transient was long assumed to be directly associated with K+ uptake and/or AQP4, although accumulating evidence suggests that they are not. Rather, activation of bicarbonate- and lactate transporters appear to lead to glial cell swelling via the activity-evoked alkaline transient, K+ -mediated glial depolarization, and metabolic demand. This review covers evidence, or lack thereof, accumulated over the last half century on the molecular mechanisms supporting activity-evoked K+ and extracellular space dynamics.
Collapse
Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
19
|
Smith AJ, Verkman AS. CrossTalk opposing view: Going against the flow: interstitial solute transport in brain is diffusive and aquaporin-4 independent. J Physiol 2019; 597:4421-4424. [PMID: 31389038 DOI: 10.1113/jp277636] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Alex J Smith
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, 94143, USA
| |
Collapse
|
20
|
Rosic B, Dukefoss DB, Åbjørsbråten KS, Tang W, Jensen V, Ottersen OP, Enger R, Nagelhus EA. Aquaporin-4-independent volume dynamics of astroglial endfeet during cortical spreading depression. Glia 2019; 67:1113-1121. [PMID: 30791140 PMCID: PMC6594042 DOI: 10.1002/glia.23604] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/02/2019] [Accepted: 02/04/2019] [Indexed: 12/13/2022]
Abstract
Cortical spreading depression (CSD) is a slowly propagating wave of depolarization of gray matter. This phenomenon is believed to underlie the migraine aura and similar waves of depolarization may exacerbate injury in a number of neurological disease states. CSD is characterized by massive ion dyshomeostasis, cell swelling, and multiphasic blood flow changes. Recently, it was shown that CSD is associated with a closure of the paravascular space (PVS), a proposed exit route for brain interstitial fluid and solutes, including excitatory and inflammatory substances that increase in the wake of CSD. The PVS closure was hypothesized to rely on swelling of astrocytic endfeet due to their high expression of aquaporin-4 (AQP4) water channels. We investigated whether CSD is associated with swelling of endfeet around penetrating arterioles in the cortex of living mice. Endfoot cross-sectional area was assessed by two-photon microscopy of mice expressing enhanced green fluorescent protein in astrocytes and related to the degree of arteriolar constriction. In anesthetized mice CSD triggered pronounced endfoot swelling that was short-lasting and coincided with the initial arteriolar constriction. Mice lacking AQP4 displayed volume changes of similar magnitude. CSD-induced endfoot swelling and arteriolar constriction also occurred in awake mice, albeit with faster kinetics than in anesthetized mice. We conclude that swelling of astrocytic endfeet is a robust event in CSD. The early onset and magnitude of the endfoot swelling is such that it may significantly delay perivascular drainage of interstitial solutes in neurological conditions where CSD plays a pathophysiological role.
Collapse
Affiliation(s)
- Brana Rosic
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
| | - Didrik B. Dukefoss
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
| | - Knut Sindre Åbjørsbråten
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
| | - Wannan Tang
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
| | - Vidar Jensen
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
| | - Ole Petter Ottersen
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
- Office of the PresidentKarolinska InstitutetStockholmSweden
| | - Rune Enger
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
- Department of NeurologyOslo University HospitalOsloNorway
| | - Erlend A. Nagelhus
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular MedicineInstitute of Basic Medical Sciences, University of OsloOsloNorway
- Department of NeurologyOslo University HospitalOsloNorway
| |
Collapse
|