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Suzuki Y, Nakamura Y, Igarashi H. Interstitial fluid flow decreases with age, especially after 50 years. Neurobiol Aging 2024; 141:14-20. [PMID: 38796942 DOI: 10.1016/j.neurobiolaging.2024.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/29/2024]
Abstract
Physiological age-related alterations in the interstitial flow in the brain, which plays an important role in waste product removal, remain unclear. Using [15O]H2O positron emission tomography (PET), water dynamics were evaluated in 63 healthy adult participants aged between 20 and 80 years. Interstitial flow was assessed by influx ratio (IR) and drain rate (DR), using time-activity concentration data. Participants were divided into four age groups with 15-year ranges, to evaluate age-related functional alterations. At least one of the indices declined significantly with age across all groups. A significant linear negative correlation between age and both indicators was found in the scatter plots (IR: R2 = 0.54, DR: R2 = 0.44); both indicators were predominantly lower after age 50 years. These results suggest interstitial flow decreases with age, especially after 50 years. These important findings can contribute to devising therapeutic interventions for neurological diseases characterized by abnormal accumulation of waste products, and suggest the need for taking measures to maintain interstitial flow starting around the age of 50 years.
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Affiliation(s)
- Yuji Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, Niigata University, Niigata, Japan.
| | - Yukimi Nakamura
- Center for Integrated Human Brain Science, Brain Research Institute, Niigata University, Niigata, Japan
| | - Hironaka Igarashi
- Center for Integrated Human Brain Science, Brain Research Institute, Niigata University, Niigata, Japan
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2
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Banerjee S, Smith IM, Hengen AC, Stroka KM. Methods for studying mammalian aquaporin biology. Biol Methods Protoc 2023; 8:bpad031. [PMID: 38046463 PMCID: PMC10689382 DOI: 10.1093/biomethods/bpad031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/29/2023] [Accepted: 11/09/2023] [Indexed: 12/05/2023] Open
Abstract
Aquaporins (AQPs), transmembrane water-conducting channels, have earned a great deal of scrutiny for their critical physiological roles in healthy and disease cell states, especially in the biomedical field. Numerous methods have been implemented to elucidate the involvement of AQP-mediated water transport and downstream signaling activation in eliciting whole cell, tissue, and organ functional responses. To modulate these responses, other methods have been employed to investigate AQP druggability. This review discusses standard in vitro, in vivo, and in silico methods for studying AQPs, especially for biomedical and mammalian cell biology applications. We also propose some new techniques and approaches for future AQP research to address current gaps in methodology.
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Affiliation(s)
- Shohini Banerjee
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Ian M Smith
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Autumn C Hengen
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Kimberly M Stroka
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland, Baltimore MD 21201, United States
- Biophysics Program, University of Maryland, MD 20742, United States
- Center for Stem Cell Biology and Regenerative Medicine, University of Maryland, Baltimore MD 21201, United States
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3
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Jia Y, Xu S, Han G, Wang B, Wang Z, Lan C, Zhao P, Gao M, Zhang Y, Jiang W, Qiu B, Liu R, Hsu YC, Sun Y, Liu C, Liu Y, Bai R. Transmembrane water-efflux rate measured by magnetic resonance imaging as a biomarker of the expression of aquaporin-4 in gliomas. Nat Biomed Eng 2023; 7:236-252. [PMID: 36376487 DOI: 10.1038/s41551-022-00960-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 10/10/2022] [Indexed: 11/16/2022]
Abstract
The water-selective channel protein aquaporin-4 (AQP4) contributes to the migration and proliferation of gliomas, and to their resistance to therapy. Here we show, in glioma cell cultures, in subcutaneous and orthotopic gliomas in rats, and in glioma tumours in patients, that transmembrane water-efflux rate is a sensitive biomarker of AQP4 expression and can be measured via conventional dynamic-contrast-enhanced magnetic resonance imaging. Water-efflux rates correlated with stages of glioma proliferation as well as with changes in the heterogeneity of intra-tumoural and inter-tumoural AQP4 in rodent and human gliomas following treatment with temozolomide and with the AQP4 inhibitor TGN020. Regions with low water-efflux rates contained higher fractions of stem-like slow-cycling cells and therapy-resistant cells, suggesting that maps of water-efflux rates could be used to identify gliomas that are resistant to therapies.
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Affiliation(s)
- Yinhang Jia
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Shangchen Xu
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Guangxu Han
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Bao Wang
- Department of Radiology, Qilu Hospital of Shandong University, Jinan, China
| | - Zejun Wang
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Chuanjin Lan
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Peng Zhao
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Meng Gao
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Yi Zhang
- Department of Radiology, Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Wenhong Jiang
- Zhejiang University School of Medicine, Hangzhou, China
| | - Biying Qiu
- Zhejiang University School of Medicine, Hangzhou, China
| | - Rui Liu
- Zhejiang University School of Medicine, Hangzhou, China
| | - Yi-Cheng Hsu
- MR Collaboration, Siemens Healthcare, Shanghai, China
| | - Yi Sun
- MR Collaboration, Siemens Healthcare, Shanghai, China
| | - Chong Liu
- MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Yingchao Liu
- Department of Neurosurgery, Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China.
- Shandong National Center for Applied Mathematics, Shandong University, Jinan, China.
| | - Ruiliang Bai
- Department of Physical Medicine and Rehabilitation of the Affiliated Sir Run Run Shaw Hospital AND Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China.
- Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China.
- MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China.
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Novel PET Biomarkers to Disentangle Molecular Pathways across Age-Related Neurodegenerative Diseases. Cells 2020; 9:cells9122581. [PMID: 33276490 PMCID: PMC7761606 DOI: 10.3390/cells9122581] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/25/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022] Open
Abstract
There is a need to disentangle the etiological puzzle of age-related neurodegenerative diseases, whose clinical phenotypes arise from known, and as yet unknown, pathways that can act distinctly or in concert. Enhanced sub-phenotyping and the identification of in vivo biomarker-driven signature profiles could improve the stratification of patients into clinical trials and, potentially, help to drive the treatment landscape towards the precision medicine paradigm. The rapidly growing field of neuroimaging offers valuable tools to investigate disease pathophysiology and molecular pathways in humans, with the potential to capture the whole disease course starting from preclinical stages. Positron emission tomography (PET) combines the advantages of a versatile imaging technique with the ability to quantify, to nanomolar sensitivity, molecular targets in vivo. This review will discuss current research and available imaging biomarkers evaluating dysregulation of the main molecular pathways across age-related neurodegenerative diseases. The molecular pathways focused on in this review involve mitochondrial dysfunction and energy dysregulation; neuroinflammation; protein misfolding; aggregation and the concepts of pathobiology, synaptic dysfunction, neurotransmitter dysregulation and dysfunction of the glymphatic system. The use of PET imaging to dissect these molecular pathways and the potential to aid sub-phenotyping will be discussed, with a focus on novel PET biomarkers.
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Inhibition of Aquaporin 4 Decreases Amyloid Aβ40 Drainage Around Cerebral Vessels. Mol Neurobiol 2020; 57:4720-4734. [PMID: 32783141 PMCID: PMC7515968 DOI: 10.1007/s12035-020-02044-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 07/24/2020] [Indexed: 01/17/2023]
Abstract
Aquaporin-4 (AQP4) is located mainly in the astrocytic end-feet around cerebral blood vessels and regulates ion and water homeostasis in the brain. While deletion of AQP4 is shown to reduce amyloid-β (Aβ) clearance and exacerbate Aβ peptide accumulation in plaques and vessels of Alzheimer's disease mouse models, the mechanism and clearing pathways involved are debated. Here, we investigated how inhibiting the function of AQP4 in healthy male C57BL/6 J mice impacts clearance of Aβ40, the more soluble Aβ isoform. Using two-photon in vivo imaging and visualizing vessels with Sulfurodamine 101 (SR101), we first showed that Aβ40 injected as a ≤ 0.5-μl volume in the cerebral cortex diffused rapidly in parenchyma and accumulated around blood vessels. In animals treated with the AQP4 inhibitor TGN-020, the perivascular Aβ40 accumulation was significantly (P < 0.001) intensified by involving four times more vessels, thus suggesting a generalized clearance defect associated with vessels. Increasing the injecting volume to ≥ 0.5 ≤ 1 μl decreased the difference of Aβ40-positive vessels observed in non-treated and AQP4 inhibitor-treated animals, although the difference was still significant (P = 0.001), suggesting that larger injection volumes could overwhelm intramural vascular clearance mechanisms. While both small and large vessels accumulated Aβ40, for the ≤ 0.5-μl volume group, the average diameter of the Aβ40-positive vessels tended to be larger in control animals compared with TGN-020-treated animals, although the difference was non-significant (P = 0.066). Using histopathology and ultrastructural microscopy, no vascular structural change was observed after a single massive dose of TGN-020. These data suggest that AQP4 deficiency is directly involved in impaired Aβ brain clearance via the peri-/para-vascular routes, and AQP4-mediated vascular clearance might counteract blood-brain barrier abnormalities and age-related vascular amyloidopathy.
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Steliga A, Kowiański P, Czuba E, Waśkow M, Moryś J, Lietzau G. Neurovascular Unit as a Source of Ischemic Stroke Biomarkers-Limitations of Experimental Studies and Perspectives for Clinical Application. Transl Stroke Res 2020; 11:553-579. [PMID: 31701356 PMCID: PMC7340668 DOI: 10.1007/s12975-019-00744-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/23/2019] [Accepted: 09/24/2019] [Indexed: 01/13/2023]
Abstract
Cerebral stroke, which is one of the most frequent causes of mortality and leading cause of disability in developed countries, often leads to devastating and irreversible brain damage. Neurological and neuroradiological diagnosis of stroke, especially in its acute phase, is frequently uncertain or inconclusive. This results in difficulties in identification of patients with poor prognosis or being at high risk for complications. It also makes difficult identification of these stroke patients who could benefit from more aggressive therapies. In contrary to the cardiovascular disease, no single biomarker is available for the ischemic stroke, addressing the abovementioned issues. This justifies the need for identifying of effective diagnostic measures characterized by high specificity and sensitivity. One of the promising avenues in this area is studies on the panels of biomarkers characteristic for processes which occur in different types and phases of ischemic stroke and represent all morphological constituents of the brains' neurovascular unit (NVU). In this review, we present the current state of knowledge concerning already-used or potentially applicable biomarkers of the ischemic stroke. We also discuss the perspectives for identification of biomarkers representative for different types and phases of the ischemic stroke, as well as for different constituents of NVU, which concentration levels correlate with extent of brain damage and patients' neurological status. Finally, a critical analysis of perspectives on further improvement of the ischemic stroke diagnosis is presented.
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Affiliation(s)
- Aleksandra Steliga
- Faculty of Health Sciences, Pomeranian University of Slupsk, 64 Bohaterów Westerplatte St., 76-200, Slupsk, Poland
| | - Przemysław Kowiański
- Faculty of Health Sciences, Pomeranian University of Slupsk, 64 Bohaterów Westerplatte St., 76-200, Slupsk, Poland.
- Department of Anatomy and Neurobiology, Medical University of Gdansk, 1 Debinki St., 80-211, Gdansk, Poland.
| | - Ewelina Czuba
- Department of Anatomy and Neurobiology, Medical University of Gdansk, 1 Debinki St., 80-211, Gdansk, Poland
| | - Monika Waśkow
- Faculty of Health Sciences, Pomeranian University of Slupsk, 64 Bohaterów Westerplatte St., 76-200, Slupsk, Poland
| | - Janusz Moryś
- Department of Anatomy and Neurobiology, Medical University of Gdansk, 1 Debinki St., 80-211, Gdansk, Poland
| | - Grażyna Lietzau
- Department of Anatomy and Neurobiology, Medical University of Gdansk, 1 Debinki St., 80-211, Gdansk, Poland
- Department of Clinical Science and Education, Södersjukhuset, Internal Medicine, Karolinska Institutet, Stockholm, Sweden
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Suzuki Y, Kitaura H, Nakamura Y, Kakita A, Huber VJ, Capozzoli N, Kwee IL, Nakada T. Skull diploë is rich in aquaporin-4. Heliyon 2020; 6:e03259. [PMID: 32042979 PMCID: PMC7002819 DOI: 10.1016/j.heliyon.2020.e03259] [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: 08/03/2019] [Revised: 10/10/2019] [Accepted: 01/15/2020] [Indexed: 12/03/2022] Open
Abstract
Aquaporin-4 (AQP4) is a water conducting membrane integral protein channel which is widely expressed in the astrocyte system of the brain. During the development of the AQP4 positron emission tomography (PET) imaging agent [11C]TGN-020 (N-(1,3,4-thiadiazol-2-yl)pyridine-3-[11C]-carboxamide), significant radioligand uptake was observed in the skull, where there was no known distribution of any aquaporin family proteins. Herein we confirmed via a newly developed method for bone-tissue immunohistology, a hitherto unrecognized distribution of AQP4, and not AQP1, in the skull. Other bony structures, by contrast, showed virtually no uptake of [11C]TGN-020, and likewise, do not express either AQP4 or AQP1. Immunohistological analysis demonstrated that the AQP4 expression in the skull is restricted to the diploë. Consequently, we suspect AQP4 plays a pivotal role in the formation and maintenance of yellow marrow and the diploë. However, elucidating the exact nature of that role will require further studies.
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Affiliation(s)
- Yuji Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan
| | - Hiroki Kitaura
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan.,Department of Pathology, Brain Research Institute, University of Niigata, Japan
| | - Yukimi Nakamura
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, University of Niigata, Japan
| | - Vincent J Huber
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan
| | | | - Ingrid L Kwee
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan.,Department of Neurology, University of California, Davis, USA
| | - Tsutomu Nakada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan.,Department of Neurology, University of California, Davis, USA
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8
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Bhattrai A, Irimia A, Van Horn JD. Neuroimaging of traumatic brain injury in military personnel: An overview. J Clin Neurosci 2019; 70:1-10. [PMID: 31331746 PMCID: PMC6861663 DOI: 10.1016/j.jocn.2019.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 07/04/2019] [Indexed: 02/02/2023]
Abstract
BACKGROUND The incidence of blunt-force traumatic brain injury (TBI) is especially prevalent in the military, where the emergency care admission rate has been reported to be 24.6-41.8 per 10,000 soldier-years. Given substantial advancements in modern neuroimaging techniques over the past decade in terms of structural, functional, and connectomic approaches, this mode of exploration can be viewed as best suited for understanding the underlying pathology and for providing proper intervention at effective time-points. APPROACH Here we survey neuroimaging studies of mild-to-severe TBI in military veterans with the intent to aid the field in the creation of a roadmap for clinicians and researchers whose aim is to understand TBI progression. DISCUSSION Recent advancements on the quantification of neurocognitive dysfunction, cellular dysfunction, intracranial pressure, cerebral blood flow, inflammation, post-traumatic neuropathophysiology, on blood serum biomarkers and on their correlation to neuroimaging findings are reviewed to hypothesize how they can be used in conjunction with one another. This may allow clinicians and scientists to comprehensively study TBI in military service members, leading to new treatment strategies for both currently-serving as well as veteran personnel, and to improve the study of TBI more broadly.
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Affiliation(s)
- Avnish Bhattrai
- USC Mark and Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, 2025 Zonal Avenue, SHN, Los Angeles, CA 90033, USA
| | - Andrei Irimia
- Ethel Percy Andrus Gerontology Center, USC Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Ave., Room 228C, Los Angeles, CA 90089-0191, USA.
| | - John Darrell Van Horn
- USC Mark and Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, 2025 Zonal Avenue, SHN, Los Angeles, CA 90033, USA.
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Suzuki Y, Nakamura Y, Yamada K, Kurabe S, Okamoto K, Aoki H, Kitaura H, Kakita A, Fujii Y, Huber VJ, Igarashi H, Kwee IL, Nakada T. Aquaporin Positron Emission Tomography Differentiates Between Grade III and IV Human Astrocytoma. Neurosurgery 2019. [PMID: 28645205 PMCID: PMC5952963 DOI: 10.1093/neuros/nyx314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Aquaporin (AQP) water channels play a significant role in mesenchymal microvascular proliferation and infiltrative growth. AQPs are highly expressed in malignant astrocytomas, and a positive correlation is observed between their expression levels and histological tumor grade. OBJECTIVE To examine the utility of aquaporin positron emission tomography (PET) for differentiating between astrocytoma grade III and grade IV using the AQP radioligand [11C]TGN-020. METHODS Fifteen astrocytoma patients, grade III (n = 7) and grade IV (n = 8), and 10 healthy volunteers underwent [11C]TGN-020 aquaporin PET imaging. Surgical tissues of astrocytoma patients were examined for histopathological grading using the WHO classification standard and expression of AQP1 and AQP4 immunohistochemically. RESULTS Mean standardized uptake values of astrocytoma grade III and IV (0.51 ± 0.11 vs 1.50 ± 0.44, respectively) were higher than normal white matter (0.17 ± 0.02, P < .001) for both tumor grades. Importantly, mean standardized uptake values of astrocytoma grade IV were significantly higher than grade III (P < .01). CONCLUSION Our study demonstrated that [11C]TGN-020 aquaporin PET imaging differentiated between astrocytoma grades III and IV. We suggest its clinical application as a noninvasive diagnostic tool would lead to advancements in the management of these malignant brain tumors.
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Affiliation(s)
- Yuji Suzuki
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Yukihiro Nakamura
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Kenichi Yamada
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Satoshi Kurabe
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan.,Department of Neurosurgery, Brain Research Ins-titute, University of Niigata, Niigata, Japan
| | - Kouichirou Okamoto
- Department of Neurosurgery, Brain Research Ins-titute, University of Niigata, Niigata, Japan
| | - Hiroshi Aoki
- Department of Neurosurgery, Brain Research Ins-titute, University of Niigata, Niigata, Japan
| | - Hiroki Kitaura
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan.,Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Yukihiko Fujii
- Department of Neurosurgery, Brain Research Ins-titute, University of Niigata, Niigata, Japan
| | - Vincent J Huber
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Hironaka Igarashi
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Ingrid L Kwee
- Department of Neurology, University of California, Davis, Davis, California
| | - Tsutomu Nakada
- Center for Integrated Human Brain Sci-ence, Brain Research Institute, University of Niigata, Niigata, Japan
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Aquaporin-4 facilitator TGN-073 promotes interstitial fluid circulation within the blood-brain barrier: [17O]H2O JJVCPE MRI study. Neuroreport 2019; 29:697-703. [PMID: 29481527 PMCID: PMC5965936 DOI: 10.1097/wnr.0000000000000990] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The blood–brain barrier (BBB), which imposes significant water permeability restriction, effectively isolates the brain from the systemic circulation. Seemingly paradoxical, the abundance of aquaporin-4 (AQP-4) on the inside of the BBB strongly indicates the presence of unique water dynamics essential for brain function. On the basis of the highly specific localization of AQP-4, namely, astrocyte end feet at the glia limitans externa and pericapillary Virchow–Robin space, we hypothesized that the AQP-4 system serves as an interstitial fluid circulator, moving interstitial fluid from the glia limitans externa to pericapillary Virchow–Robin space to ensure proper glymphatic flow draining into the cerebrospinal fluid. The hypothesis was tested directly using the AQP-4 facilitator TGN-073 developed in our laboratory, and [17O]H2O JJ vicinal coupling proton exchange MRI, a method capable of tracing water molecules delivered into the blood circulation. The results unambiguously showed that facilitation of AQP-4 by TGN-073 increased turnover of interstitial fluid through the system, resulting in a significant reduction in [17O]H2O contents of cortex with normal flux into the cerebrospinal fluid. The study further suggested that in addition to providing the necessary water for proper glymphatic flow, the AQP-4 system produces a water gradient within the interstitial space promoting circulation of interstitial fluid within the BBB.
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AQP1 and AQP4 Contribution to Cerebrospinal Fluid Homeostasis. Cells 2019; 8:cells8020197. [PMID: 30813473 PMCID: PMC6406452 DOI: 10.3390/cells8020197] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 12/23/2022] Open
Abstract
Aquaporin 1 (AQP1), expressed in epithelial cells of the choroid plexus, and aquaporin 4 (AQP4) present in ependymal cells and glia limitants have been proposed to play a significant role in cerebrospinal fluid (CSF) production and homeostasis. However, the specific contribution of each water channel to these functions remains unknown, being a subject of debate during the last years. Here, we analyzed in detail how AQP1 and AQP4 participate in different aspects of the CSF homeostasis such as the load and drainage of ventricles, and further explored if these proteins play a role in the ventricular compliance. To do that, we carried out records of intraventricular pressure and CSF outflow, and evaluated ventricular volume by magnetic resonance imaging in AQP1−/−, AQP4−/−, double AQP1−/−-AQP4−/− knock out and wild type mice controls. The analysis performed clearly showed that both AQPs have a significant participation in the CSF production, and additionally revealed that the double AQP1-AQP4 mutation alters the CSF drainage and the ventricular compliance. The data reported here indicate a significant extra-choroidal CSF formation mediated by AQP4, supporting the idea of an important and constant CSF production/absorption process, sustained by efflux/influx of water between brain capillaries and interstitial fluid. Moreover, our results suggest the participation of AQPs in structural functions also related with CSF homeostasis such as the distensibility capacity of the ventricular system.
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Association of Genetic Variation at AQP4 Locus with Vascular Depression. Biomolecules 2018; 8:biom8040164. [PMID: 30563176 PMCID: PMC6316852 DOI: 10.3390/biom8040164] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 02/07/2023] Open
Abstract
Despite its substantial clinical importance, specific genetic variants associated with depression have not yet been identified. We sought to identify genetic variants associated with depression by (a) focusing on a more homogenous subsample (vascular depression) and (b) applying a three-stage approach. First, we contacted 730 participants with a confirmed atherosclerotic disease (coronary artery disease) from a population-based study population (German Myocardial Infarction Family Study IV) for psychiatric assessment with the Mini International Neuropsychiatric Interview. Second, we genotyped these patients using genome-wide single nucleotide polymorphism (SNP) arrays. Third, we characterized the SNP via in-silico analysis. The final sample consisted of 342 patients (78.3% male, age = 63.2 ± 9.9 years), 22.8% with a severe depressive disorder. Variant rs528732638 on chromosome 18q11.2 was a genome-wide significant variant and was associated with 3.6-fold increase in the odds of lifetime depression. The locus belongs to a linkage disequilibrium block showing expression quantitative trait loci effects on three putative cis-regulated genes, including the aquaporin 4 (AQP4) locus. AQP4 is already known to mediate the formation of ischemic edema in the brain and heart, increasing the size and extent of resulting lesions. Our findings indicate that AQP4 may also play a role in the etiopathology of vascular depression.
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Inhibition of Aquaporin-4 Improves the Outcome of Ischaemic Stroke and Modulates Brain Paravascular Drainage Pathways. Int J Mol Sci 2017; 19:ijms19010046. [PMID: 29295526 PMCID: PMC5795996 DOI: 10.3390/ijms19010046] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 01/09/2023] Open
Abstract
Aquaporin-4 (AQP4) is the most abundant water channel in the brain, and its inhibition before inducing focal ischemia, using the AQP4 inhibitor TGN-020, has been showed to reduce oedema in imaging studies. Here, we aimed to evaluate, for the first time, the histopathological effects of a single dose of TGN-020 administered after the occlusion of the medial cerebral artery (MCAO). On a rat model of non-reperfusion ischemia, we have assessed vascular densities, albumin extravasation, gliosis, and apoptosis at 3 and 7 days after MCAO. TGN-020 significantly reduced oedema, glial scar, albumin effusion, and apoptosis, at both 3 and 7 days after MCAO. The area of GFAP-positive gliotic rim decreased, and 3D fractal analysis of astrocytic processes revealed a less complex architecture, possibly indicating water accumulating in the cytoplasm. Evaluation of the blood vessels revealed thicker basement membranes colocalizing with exudated albumin in the treated animals, suggesting that inhibition of AQP4 blocks fluid flow towards the parenchyma in the paravascular drainage pathways of the interstitial fluid. These findings suggest that a single dose of an AQP4 inhibitor can reduce brain oedema, even if administered after the onset of ischemia, and AQP4 agonists/antagonists might be effective modulators of the paravascular drainage flow.
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Suzuki K, Yamada K, Nakada K, Suzuki Y, Watanabe M, Kwee IL, Nakada T. MRI characteristics of the glia limitans externa: A 7T study. Magn Reson Imaging 2017; 44:140-145. [PMID: 28870515 DOI: 10.1016/j.mri.2017.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 08/31/2017] [Indexed: 11/26/2022]
Abstract
PURPOSE To perform a systematic analysis of the intrinsic contrast parameters of the FLAIR hyperintense rim (FHR), a thin layer of high intensity covering the entire surface of the cerebral cortex detected on fluid-attenuated inversion recovery (FLAIR) sequence T2 weighted imaging performed on a 7T system, in an attempt to identify its anatomical correlate. METHODS Fast spin echo inversion recovery (FSE-IR) and cardiac-gated fast spin echo (FSE) images were obtained with defined parameters in eight normal volunteers on a 7 T MRI system to determine T2 and proton density, T1 characteristics. K-means clustering analysis of parameter sets was performed using MATLAB version R2015b for the purpose of identifying the cluster reflecting FHR. The results were subsequently confirmed by independent component analysis (ICA) based on T1 behavior on FSE-IR using a MATLAB script of FastICA algorithm. RESULTS The structure giving rise to FHR was found to have a unique combination of intrinsic contrast parameters of low proton density, long T2, and disproportionally short T1. The findings are in strong agreement with the functional and structural specifics of the glia limitans externa (GLE), a structure composed of snuggled endfeet of astrocytes containing abundant aquaporin-4 (AQP-4), the main water channel of the brain. CONCLUSION Intrinsic contrast parameters of FHR reflect structural and functional specifics of the GLE, and their values are highly dependent on the physiologic functionality of AQP-4. Microscopic imaging on a 7T system and analysis of GLE contrast parameters can be developed into a method for evaluating AQP-4 functionality.
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Affiliation(s)
- Kiyotaka Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Kenichi Yamada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Kazunori Nakada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Yuji Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Masaki Watanabe
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Ingrid L Kwee
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan; Department of Neurology, University of California, Davis, USA
| | - Tsutomu Nakada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan; Department of Neurology, University of California, Davis, USA.
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Sullan MJ, Asken BM, Jaffee MS, DeKosky ST, Bauer RM. Glymphatic system disruption as a mediator of brain trauma and chronic traumatic encephalopathy. Neurosci Biobehav Rev 2017; 84:316-324. [PMID: 28859995 DOI: 10.1016/j.neubiorev.2017.08.016] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 08/17/2017] [Accepted: 08/21/2017] [Indexed: 12/14/2022]
Abstract
Traumatic brain injury (TBI) is an increasingly important issue among veterans, athletes and the general public. Difficulties with sleep onset and maintenance are among the most commonly reported symptoms following injury, and sleep debt is associated with increased accumulation of beta amyloid (Aβ) and phosphorylated tau (p-tau) in the interstitial space. Recent research into the glymphatic system, a lymphatic-like metabolic clearance mechanism in the central nervous system (CNS) which relies on cerebrospinal fluid (CSF), interstitial fluid (ISF), and astrocytic processes, shows that clearance is potentiated during sleep. This system is damaged in the acute phase following mTBI, in part due to re-localization of aquaporin-4 channels away from astrocytic end feet, resulting in reduced potential for waste removal. Long-term consequences of chronic dysfunction within this system in the context of repetitive brain trauma and insomnia have not been established, but potentially provide one link in the explanatory chain connecting repetitive TBI with later neurodegeneration. Current research has shown p-tau deposition in perivascular spaces and along interstitial pathways in chronic traumatic encephalopathy (CTE), pathways related to glymphatic flow; these are the main channels by which metabolic waste is cleared. This review addresses possible links between mTBI-related damage to glymphatic functioning and physiological changes found in CTE, and proposes a model for the mediating role of sleep disruption in increasing the risk for developing CTE-related pathology and subsequent clinical symptoms following repetitive brain trauma.
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Affiliation(s)
- Molly J Sullan
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, PO Box 100165, Gainesville, FL 32610, USA.
| | - Breton M Asken
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, PO Box 100165, Gainesville, FL 32610, USA.
| | - Michael S Jaffee
- Department of Neurology, School of Medicine, University of Florida, 2000 SW Archer Rd, Gainesville, FL 32610, USA.
| | - Steven T DeKosky
- Department of Neurology, McKnight Brain Institute, University of Florida, PO Box 100236, Gainesville, FL 32610, USA.
| | - Russell M Bauer
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, PO Box 100165, Gainesville, FL 32610, USA; Brain Rehabilitation Research Center, North Florida/South Georgia Health System (NF/SG VHS), USA.
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Van Horn JD, Bhattrai A, Irimia A. Multimodal Imaging of Neurometabolic Pathology due to Traumatic Brain Injury. Trends Neurosci 2016; 40:39-59. [PMID: 27939821 DOI: 10.1016/j.tins.2016.10.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 10/21/2016] [Accepted: 10/25/2016] [Indexed: 12/28/2022]
Abstract
The impact of traumatic brain injury (TBI) involves a combination of complex biochemical processes beginning with the initial insult and lasting for days, months and even years post-trauma. These changes range from neuronal integrity losses to neurotransmitter imbalance and metabolite dysregulation, leading to the release of pro- or anti-apoptotic factors which mediate cell survival or death. Such dynamic processes affecting the brain's neurochemistry can be monitored using a variety of neuroimaging techniques, whose combined use can be particularly useful for understanding patient-specific clinical trajectories. Here, we describe how TBI changes the metabolism of essential neurochemical compounds, summarize how neuroimaging approaches facilitate the study of such alterations, and highlight promising ways in which neuroimaging can be used to investigate post-TBI changes in neurometabolism.
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Affiliation(s)
- John Darrell Van Horn
- USC Mark and Mary Stevens Neuroimaging and Informatics Institute, 2025 Zonal Avenue, Keck School of Medicine of USC, University of Southern California, Los Angeles, California 90033, USA.
| | - Avnish Bhattrai
- USC Mark and Mary Stevens Neuroimaging and Informatics Institute, 2025 Zonal Avenue, Keck School of Medicine of USC, University of Southern California, Los Angeles, California 90033, USA
| | - Andrei Irimia
- USC Mark and Mary Stevens Neuroimaging and Informatics Institute, 2025 Zonal Avenue, Keck School of Medicine of USC, University of Southern California, Los Angeles, California 90033, USA
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MATSUMAE M, SATO O, HIRAYAMA A, HAYASHI N, TAKIZAWA K, ATSUMI H, SORIMACHI T. Research into the Physiology of Cerebrospinal Fluid Reaches a New Horizon: Intimate Exchange between Cerebrospinal Fluid and Interstitial Fluid May Contribute to Maintenance of Homeostasis in the Central Nervous System. Neurol Med Chir (Tokyo) 2016; 56:416-41. [PMID: 27245177 PMCID: PMC4945600 DOI: 10.2176/nmc.ra.2016-0020] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/20/2016] [Indexed: 12/23/2022] Open
Abstract
Cerebrospinal fluid (CSF) plays an essential role in maintaining the homeostasis of the central nervous system. The functions of CSF include: (1) buoyancy of the brain, spinal cord, and nerves; (2) volume adjustment in the cranial cavity; (3) nutrient transport; (4) protein or peptide transport; (5) brain volume regulation through osmoregulation; (6) buffering effect against external forces; (7) signal transduction; (8) drug transport; (9) immune system control; (10) elimination of metabolites and unnecessary substances; and finally (11) cooling of heat generated by neural activity. For CSF to fully mediate these functions, fluid-like movement in the ventricles and subarachnoid space is necessary. Furthermore, the relationship between the behaviors of CSF and interstitial fluid in the brain and spinal cord is important. In this review, we will present classical studies on CSF circulation from its discovery over 2,000 years ago, and will subsequently introduce functions that were recently discovered such as CSF production and absorption, water molecule movement in the interstitial space, exchange between interstitial fluid and CSF, and drainage of CSF and interstitial fluid into both the venous and the lymphatic systems. Finally, we will summarize future challenges in research. This review includes articles published up to February 2016.
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Affiliation(s)
- Mitsunori MATSUMAE
- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa
| | | | - Akihiro HIRAYAMA
- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa
| | - Naokazu HAYASHI
- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa
| | - Ken TAKIZAWA
- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa
| | - Hideki ATSUMI
- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa
| | - Takatoshi SORIMACHI
- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa
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Cary BP, Brooks AF, Fawaz MV, Drake LR, Desmond TJ, Sherman P, Quesada CA, Scott PJH. Synthesis and Evaluation of [(18)F]RAGER: A First Generation Small-Molecule PET Radioligand Targeting the Receptor for Advanced Glycation Endproducts. ACS Chem Neurosci 2016; 7:391-8. [PMID: 26771209 DOI: 10.1021/acschemneuro.5b00319] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The receptor for advanced glycation endproducts (RAGE) is a 35 kDa transmembrane receptor that belongs to the immunoglobulin superfamily of cell surface molecules. Its role in Alzheimer's disease (AD) is complex, but it is thought to mediate influx of circulating amyloid-β into the brain as well as amplify Aβ-induced pathogenic responses. RAGE is therefore of considerable interest as both a diagnostic and a therapeutic target in AD. Herein we report the synthesis and preliminary preclinical evaluation of [(18)F]RAGER, the first small molecule PET radiotracer for RAGE (Kd = 15 nM). Docking studies proposed a likely binding interaction between RAGE and RAGER, [(18)F]RAGER autoradiography showed colocalization with RAGE identified by immunohistochemistry in AD brain samples, and [(18)F]RAGER microPET confirmed CNS penetration and increased uptake in areas of the brain known to express RAGE. This first generation radiotracer represents initial proof-of-concept and a promising first step toward quantifying CNS RAGE activity using PET. However, there were high levels of nonspecific [(18)F]RAGER binding in vitro, likely due to its high log P (experimental log P = 3.5), and rapid metabolism of [(18)F]RAGER in rat liver microsome studies. Therefore, development of second generation ligands with improved imaging properties would be advantageous prior to anticipated translation into clinical PET imaging studies.
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Affiliation(s)
- Brian P. Cary
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Allen F. Brooks
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Maria V. Fawaz
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- The
Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lindsey R. Drake
- The
Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Timothy J. Desmond
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- The
Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Brinker T, Stopa E, Morrison J, Klinge P. A new look at cerebrospinal fluid circulation. Fluids Barriers CNS 2014; 11:10. [PMID: 24817998 PMCID: PMC4016637 DOI: 10.1186/2045-8118-11-10] [Citation(s) in RCA: 484] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/18/2014] [Indexed: 12/11/2022] Open
Abstract
According to the traditional understanding of cerebrospinal fluid (CSF) physiology, the majority of CSF is produced by the choroid plexus, circulates through the ventricles, the cisterns, and the subarachnoid space to be absorbed into the blood by the arachnoid villi. This review surveys key developments leading to the traditional concept. Challenging this concept are novel insights utilizing molecular and cellular biology as well as neuroimaging, which indicate that CSF physiology may be much more complex than previously believed. The CSF circulation comprises not only a directed flow of CSF, but in addition a pulsatile to and fro movement throughout the entire brain with local fluid exchange between blood, interstitial fluid, and CSF. Astrocytes, aquaporins, and other membrane transporters are key elements in brain water and CSF homeostasis. A continuous bidirectional fluid exchange at the blood brain barrier produces flow rates, which exceed the choroidal CSF production rate by far. The CSF circulation around blood vessels penetrating from the subarachnoid space into the Virchow Robin spaces provides both a drainage pathway for the clearance of waste molecules from the brain and a site for the interaction of the systemic immune system with that of the brain. Important physiological functions, for example the regeneration of the brain during sleep, may depend on CSF circulation.
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Affiliation(s)
- Thomas Brinker
- Department of Neurosurgery, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA
| | - Edward Stopa
- Department of Neurosurgery, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA
| | - John Morrison
- Department of Neurosurgery, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA
| | - Petra Klinge
- Department of Neurosurgery, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA
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Brain water channel proteins in health and disease. Mol Aspects Med 2012; 33:562-78. [DOI: 10.1016/j.mam.2012.03.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 03/28/2012] [Accepted: 03/31/2012] [Indexed: 02/07/2023]
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