RESUMEN
Cerebrospinal fluid (CSF) is responsible for maintaining brain homeostasis through nutrient delivery and waste removal for the central nervous system (CNS). Here, we demonstrate extensive CSF flow throughout the peripheral nervous system (PNS) by tracing distribution of multimodal 1.9-nanometer gold nanoparticles, roughly the size of CSF circulating proteins, infused within the lateral cerebral ventricle (a primary site of CSF production). CSF-infused 1.9-nanometer gold transitions from CNS to PNS at root attachment/transition zones and distributes through the perineurium and endoneurium, with ultimate delivery to axoplasm of distal peripheral nerves. Larger 15-nanometer gold fails to transit from CNS to PNS and instead forms "dye-cuffs," as predicted by current dogma of CSF restriction within CNS, identifying size limitations in central to peripheral flow. Intravenous 1.9-nanometer gold is unable to cross the blood-brain/nerve barrier. Our findings suggest that CSF plays a consistent role in maintaining homeostasis throughout the nervous system with implications for CNS and PNS therapy and neural drug delivery.
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Líquido Cefalorraquídeo , Nervios Periféricos , Animales , Líquido Cefalorraquídeo/metabolismo , Líquido Cefalorraquídeo/fisiología , Nervios Periféricos/fisiología , Oro/química , Sistema Nervioso Periférico/fisiología , Nanopartículas del Metal/química , Sistema Nervioso Central/fisiología , Sistema Nervioso Central/metabolismo , Barrera Hematoencefálica/metabolismo , Ratas , RatonesRESUMEN
BACKGROUND: The blood-cerebrospinal fluid barrier (BCSFB) comprises the choroid plexus epithelia. It is important for brain development, maintenance, function, and especially for maintaining immune homeostasis in the cerebrospinal fluid (CSF). Although previous studies have shown that the peripheral immune function of the body is impaired upon exposure to microgravity, no studies have reported changes in immune cells and cytokines in the CSF that reflect neuroimmune status. The purpose of this study is to investigate the alterations in cerebrospinal fluid (CSF) immune homeostasis induced by microgravity and its mechanisms. This research is expected to provide basic data for brain protection of astronauts during spaceflight. METHODS: The proportions of immune cells in the CSF and peripheral blood (PB) of SMG rats were analyzed using flow cytometry. Immune function was evaluated by measuring cytokine concentrations using the Luminex method. The histomorphology and ultrastructure of the choroid plexus epithelia were determined. The concentrations of intercellular junction proteins in choroid plexus epithelial cells, including vascular endothelial-cadherin (VE-cadherin), zonula occludens 1 (ZO-1), Claudin-1 and occludin, were detected using western blotting and immunofluorescence staining to characterize BCSFB injury. RESULTS: We found that SMG caused significant changes in the proportion of CD4 and CD8 T cells in the CSF and a significant increase in the levels of cytokines (GRO/KC, IL-18, MCP-1, and RANTES). In the PB, there was a significant decrease in the proportion of T cells and NKT cells and a significant increase in cytokine levels (GRO/KC, IL-18, MCP-1, and TNF-α). Additionally, we observed that the trends in immune markers in the PB and CSF were synchronized within specific SMG durations, suggesting that longer SMG periods (≥21 days) have a more pronounced impact on immune markers. Furthermore, 21d-SMG resulted in ultrastructural disruption and downregulated expression of intercellular junction proteins in rat choroid plexus epithelial cells. CONCLUSIONS: We found that SMG disrupts the BCSFB and affects the CSF immune homeostasis. This study provides new insights into the health protection of astronauts during spaceflight.
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Barrera Hematoencefálica , Plexo Coroideo , Citocinas , Homeostasis , Simulación de Ingravidez , Animales , Homeostasis/fisiología , Ratas , Plexo Coroideo/inmunología , Plexo Coroideo/metabolismo , Masculino , Citocinas/metabolismo , Citocinas/líquido cefalorraquídeo , Barrera Hematoencefálica/metabolismo , Barrera Hematoencefálica/inmunología , Líquido Cefalorraquídeo/inmunología , Líquido Cefalorraquídeo/metabolismo , Ratas Sprague-Dawley , Células Epiteliales/metabolismo , Células Epiteliales/inmunologíaAsunto(s)
Líquido Cefalorraquídeo , Animales , Humanos , Líquido Cefalorraquídeo/metabolismo , Cavidad NasalRESUMEN
Intellectual and developmental disabilities result from abnormal nervous system development. Over a 1,000 genes have been associated with intellectual and developmental disabilities, driving continued efforts toward dissecting variant functionality to enhance our understanding of the disease mechanism. This report identified two novel variants in CC2D1A in a cohort of four patients from two unrelated families. We used multiple model systems for functional analysis, including Xenopus, Drosophila, and patient-derived fibroblasts. Our experiments revealed that cc2d1a is expressed explicitly in a spectrum of ciliated tissues, including the left-right organizer, epidermis, pronephric duct, nephrostomes, and ventricular zone of the brain. In line with this expression pattern, loss of cc2d1a led to cardiac heterotaxy, cystic kidneys, and abnormal CSF circulation via defective ciliogenesis. Interestingly, when we analyzed brain development, mutant tadpoles showed abnormal CSF circulation only in the midbrain region, suggesting abnormal local CSF flow. Furthermore, our analysis of the patient-derived fibroblasts confirmed defective ciliogenesis, further supporting our observations. In summary, we revealed novel insight into the role of CC2D1A by establishing its new critical role in ciliogenesis and CSF circulation.
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Cilios , Ciliopatías , Discapacidad Intelectual , Humanos , Animales , Discapacidad Intelectual/genética , Masculino , Cilios/metabolismo , Femenino , Ciliopatías/genética , Ciliopatías/metabolismo , Fibroblastos/metabolismo , Mutación , Riñón/metabolismo , Encéfalo/metabolismo , Linaje , Xenopus , Líquido Cefalorraquídeo/metabolismoRESUMEN
Lipid nanoparticles (LNPs) have successfully entered the clinic for the delivery of mRNA- and siRNA-based therapeutics, most recently as vaccines for COVID-19. Nevertheless, there is a lack of understanding regarding their in vivo behavior, in particular cell targeting. Part of this LNP tropism is based on the adherence of endogenous protein to the particle surface. This protein forms a so-called corona that can change, amongst other things, the circulation time, biodistribution and cellular uptake of these particles. The formation of this protein corona, in turn, is dependent on the nanoparticle properties (e.g., size, charge, surface chemistry and hydrophobicity) as well as the biological environment from which it is derived. With the potential of gene therapy to target virtually any disease, administration sites other than intravenous route are considered, resulting in tissue specific protein coronas. For neurological diseases, intracranial administration of LNPs results in a cerebral spinal fluid derived protein corona, possibly changing the properties of the lipid nanoparticle compared to intravenous administration. Here, the differences between plasma and CSF derived protein coronas on a clinically relevant LNP formulation were studied in vitro. Protein analysis showed that LNPs incubated in human CSF (C-LNPs) developed a protein corona composition that differed from that of LNPs incubated in plasma (P-LNPs). Lipoproteins as a whole, but in particular apolipoprotein E, represented a higher percentage of the total protein corona on C-LNPs than on P-LNPs. This resulted in improved cellular uptake of C-LNPs compared to P-LNPs, regardless of cell origin. Importantly, the higher LNP uptake did not directly translate into more efficient cargo delivery, underlining that further assessment of such mechanisms is necessary. These findings show that biofluid specific protein coronas alter LNP functionality, suggesting that the site of administration could affect LNP efficacy in vivo and needs to be considered during the development of the formulation.
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Lípidos , Nanopartículas , Corona de Proteínas , Nanopartículas/química , Humanos , Corona de Proteínas/metabolismo , Lípidos/química , Líquido Cefalorraquídeo/metabolismo , LiposomasRESUMEN
Classical migraine patients experience aura, which is transient neurological deficits associated with cortical spreading depression (CSD), preceding headache attacks. It is not currently understood how a pathological event in cortex can affect peripheral sensory neurons. In this study, we show that cerebrospinal fluid (CSF) flows into the trigeminal ganglion, establishing nonsynaptic signaling between brain and trigeminal cells. After CSD, ~11% of the CSF proteome is altered, with up-regulation of proteins that directly activate receptors in the trigeminal ganglion. CSF collected from animals exposed to CSD activates trigeminal neurons in naïve mice in part by CSF-borne calcitonin gene-related peptide (CGRP). We identify a communication pathway between the central and peripheral nervous system that might explain the relationship between migrainous aura and headache.
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Péptido Relacionado con Gen de Calcitonina , Depresión de Propagación Cortical , Trastornos Migrañosos , Ganglio del Trigémino , Animales , Ratones , Péptido Relacionado con Gen de Calcitonina/líquido cefalorraquídeo , Péptido Relacionado con Gen de Calcitonina/metabolismo , Líquido Cefalorraquídeo/metabolismo , Modelos Animales de Enfermedad , Trastornos Migrañosos/líquido cefalorraquídeo , Trastornos Migrañosos/metabolismo , Trastornos Migrañosos/fisiopatología , Proteoma/metabolismo , Transducción de Señal , Ganglio del Trigémino/metabolismo , Ganglio del Trigémino/fisiopatologíaRESUMEN
BACKGROUND: The pleiotropic effects of the melanocortin system show promise in overcoming limitations associated with large variations in opioid analgesic effectiveness observed in equine practice. Of particular interest is variation in the melanocortin-1-receptor (MC1R) gene, which dictates pigment type expression through its epistatic interaction with the agouti signalling protein (ASIP) gene. MC1R has previously been implicated in opioid efficacy in other species; however, this relationship is yet to be explored in horses. In this study, analgesic effectiveness was scored (1-3) based on noted response to dura penetration during the performance of cerebrospinal fluid centisis after sedation and tested for association with known genetic regions responsible for pigmentation variation in horses. RESULTS: The chestnut phenotype was statistically significant (P < 0.05) in lowering analgesic effectiveness when compared to the bay base coat colour. The 11bp indel in ASIP known to cause the black base coat colour was not significant (P>0.05); however, six single nucleotide polymorphisms (SNPs) within the genomic region encoding the ASIP gene and one within MC1R were identified as being nominally significant (P<0.05) in association with opioid analgesic effectiveness. This included the location of the known e MC1R variant resulting in the chestnut coat colour. CONCLUSIONS: The current study provides promising evidence for important links between pigmentation genes and opioid effectiveness in horses. The application of an easily identifiable phenotype indicating variable sensitivity presents a promising opportunity for accessible precision medicine in the use of analgesics and warrants further investigation.
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Analgésicos Opioides , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 1 , Animales , Caballos , Analgésicos Opioides/farmacología , Analgésicos Opioides/uso terapéutico , Receptor de Melanocortina Tipo 1/genética , Pigmentación/genética , Proteína de Señalización Agouti/genética , Masculino , Femenino , Fenotipo , Líquido Cefalorraquídeo/metabolismoRESUMEN
The choroid plexus (ChP) produces cerebrospinal fluid (CSF). It also contributes to brain development and serves as the CSF-blood barrier. Prior studies have identified transporters on the epithelial cells that transport water and ions from the blood vasculature to the ventricles and tight junctions involved in the CSF-blood barrier. Yet, how the ChP epithelial cells control brain physiology remains unresolved. We use zebrafish to provide insights into the physiological roles of the ChP. Upon histological and transcriptomic analyses, we identify that the zebrafish ChP is conserved with mammals and expresses transporters involved in CSF secretion. Next, we show that the ChP epithelial cells secrete proteins into CSF. By ablating the ChP epithelial cells, we identify a reduction of the ventricular sizes without alterations of the CSF-blood barrier. Altogether, our findings reveal that the zebrafish ChP is conserved and contributes to the size and homeostasis of the brain ventricles.
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Ventrículos Cerebrales , Plexo Coroideo , Homeostasis , Pez Cebra , Animales , Pez Cebra/metabolismo , Plexo Coroideo/metabolismo , Ventrículos Cerebrales/metabolismo , Proteínas de Pez Cebra/metabolismo , Proteínas de Pez Cebra/genética , Líquido Cefalorraquídeo/metabolismo , Células Epiteliales/metabolismo , Evolución Biológica , Barrera Hematoencefálica/metabolismoRESUMEN
This study examined the association between hearing loss in sporadic vestibular schwannoma patients and the proteome of perilymph (PL), cerebrospinal fluid (CSF), and vestibular schwannoma. Intraoperative sampling of PL and of CSF, and biopsy of vestibular schwannoma tissue, was performed in 32, 32, and 20 patients with vestibular schwannoma, respectively. Perilymph and CSF in three patients with meningioma and normal hearing were also sampled. The proteomes were identified by liquid chromatography coupled to high-resolution tandem mass spectrometry. Preoperative hearing function of the patients was evaluated with pure tone audiometry, with mean values at frequencies of 500, 1000, 2000, and 4000 Hz (PTA4) in the tumor-affected ear used to delineate three hearing groups. Analysis of the PL samples revealed significant upregulation of complement factor H-related protein 2 (CFHR2) in patients with severe to profound hearing loss after false discovery rate correction. Pathway analysis of biofunctions revealed higher activation scores in the severe/profound hearing loss group of leukocyte migration, viral infection, and migration of cells in PL. Upregulation of CFHR2 and activation of these pathways indicate chronic inflammation in the cochlea of vestibular schwannoma patients with severe to profound hearing loss compared with patients with normal hearing or mild hearing loss.
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Pérdida Auditiva , Neuroma Acústico , Perilinfa , Proteoma , Humanos , Neuroma Acústico/líquido cefalorraquídeo , Neuroma Acústico/metabolismo , Neuroma Acústico/patología , Femenino , Masculino , Persona de Mediana Edad , Perilinfa/metabolismo , Pérdida Auditiva/líquido cefalorraquídeo , Adulto , Anciano , Líquido Cefalorraquídeo/metabolismo , Audiometría de Tonos PurosRESUMEN
Cerebrospinal fluid (CSF) is a body fluid that can be used for the diagnosis of various diseases. However, CSF collection requires an invasive and painful procedure called a lumbar puncture (LP). This procedure is applied to any patient with a known risk of central nervous system (CNS) damage or neurodegenerative disease, regardless of their age range. Hence, this can be a very painful procedure, especially in infants and elderly patients. On the other hand, the detection of disease biomarkers in CSF makes diagnoses as accurate as possible. This review aims to explore novel electrochemical biosensing platforms that have impacted biomedical science. Biosensors have emerged as techniques to accelerate the detection of known biomarkers in body fluids such as CSF. Biosensors can be designed and modified in various ways and shapes according to their ultimate applications to detect and quantify biomarkers of interest. This process can also significantly influence the detection and diagnosis of CSF. Hence, it is important to understand the role of this technology in the rapidly progressing field of biomedical science.
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Biomarcadores , Técnicas Biosensibles , Líquido Cefalorraquídeo , Diagnóstico Precoz , Humanos , Técnicas Biosensibles/métodos , Biomarcadores/líquido cefalorraquídeo , Líquido Cefalorraquídeo/química , Líquido Cefalorraquídeo/metabolismo , Enfermedades Raras/diagnóstico , Enfermedades Neurodegenerativas/diagnóstico , Enfermedades Neurodegenerativas/líquido cefalorraquídeo , Técnicas Electroquímicas/métodosRESUMEN
BACKGROUND: HIV-associated neurocognitive disorders (HAND) still affects persons with HIV (PWH) and their pathogenesis is not completely understood. We aimed to explore the association between plasma and cerebrospinal fluid (CSF) markers of blood-brain barrier (BBB) impairment and HAND in untreated PWH. DESIGN: Cross-sectional study. METHODS: We enrolled untreated PWH, who underwent blood examinations and lumbar puncture to measure inflammation (IL-15, TNF-α), BBB damage (zonulin and tight junction proteins, tight junction proteins: occludin, claudin-5) and endothelial adhesion molecules (VCAM-1, ICAM-1). A comprehensive neurocognitive battery was used to diagnose HAND (Frascati criteria). RESULTS: Twenty-one patients (21/78, 26.9%) patients presented HAND (100% ANI). HAND patients displayed more frequently non-CNS AIDS-defining conditions, lower nadir CD4 + T cells and increased CD4 + T-cell exhaustion (lower CD4 + CD127 + and CD4 + CD45RA + T-cell percentages), in comparison to individuals without cognitive impairment. Furthermore, HAND was characterized by higher plasma inflammation (IL-15) but lower CSF levels of biomarkers of BBB impairment (zonulin and occludin). The association between BBB damage with HAND was confirmed by fitting a multivariable logistic regression. CSF/plasma endothelial adhesion molecules were not associated with HAND but with a poor performance in different cognitive domains. CONCLUSION: By showing heightened inflammation and BBB impairment, our study suggests loss of BBB integrity as a possible factor contributing to the development of HAND in untreated PWH.
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Barrera Hematoencefálica , Infecciones por VIH , Proteínas de Uniones Estrechas , Humanos , Masculino , Femenino , Estudios Transversales , Persona de Mediana Edad , Adulto , Proteínas de Uniones Estrechas/metabolismo , Infecciones por VIH/complicaciones , Biomarcadores/líquido cefalorraquídeo , Biomarcadores/sangre , Líquido Cefalorraquídeo/química , Líquido Cefalorraquídeo/metabolismo , Disfunción Cognitiva/etiologíaRESUMEN
BACKGROUND: Impaired glymphatic clearance of cerebral metabolic products and fluids contribute to traumatic and ischemic brain edema and neurodegeneration in preclinical models. Glymphatic perivascular cerebrospinal fluid flow varies between anesthetics possibly due to changes in vasomotor tone and thereby in the dynamics of the periarterial cerebrospinal fluid (CSF)-containing space. To better understand the influence of anesthetics and carbon dioxide levels on CSF dynamics, this study examined the effect of periarterial size modulation on CSF distribution by changing blood carbon dioxide levels and anesthetic regimens with opposing vasomotor influences: vasoconstrictive ketamine-dexmedetomidine (K/DEX) and vasodilatory isoflurane. METHODS: End-tidal carbon dioxide (ETco2) was modulated with either supplemental inhaled carbon dioxide to reach hypercapnia (Etco2, 80 mmHg) or hyperventilation (Etco2, 20 mmHg) in tracheostomized and anesthetized female rats. Distribution of intracisternally infused radiolabeled CSF tracer 111In-diethylamine pentaacetate was assessed for 86 min in (1) normoventilated (Etco2, 40 mmHg) K/DEX; (2) normoventilated isoflurane; (3) hypercapnic K/DEX; and (4) hyperventilated isoflurane groups using dynamic whole-body single-photon emission tomography. CSF volume changes were assessed with magnetic resonance imaging. RESULTS: Under normoventilation, cortical CSF tracer perfusion, perivascular space size around middle cerebral arteries, and intracranial CSF volume were higher under K/DEX compared with isoflurane (cortical maximum percentage of injected dose ratio, 2.33 [95% CI, 1.35 to 4.04]; perivascular size ratio 2.20 [95% CI, 1.09 to 4.45]; and intracranial CSF volume ratio, 1.90 [95% CI, 1.33 to 2.71]). Under isoflurane, tracer was directed to systemic circulation. Under K/DEX, the intracranial tracer distribution and CSF volume were uninfluenced by hypercapnia compared with normoventilation. Intracranial CSF tracer distribution was unaffected by hyperventilation under isoflurane despite a 28% increase in CSF volume around middle cerebral arteries. CONCLUSIONS: K/DEX and isoflurane overrode carbon dioxide as a regulator of CSF flow. K/DEX could be used to preserve CSF space and dynamics in hypercapnia, whereas hyperventilation was insufficient to increase cerebral CSF perfusion under isoflurane.
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Dióxido de Carbono , Líquido Cefalorraquídeo , Sistema Glinfático , Ratas Sprague-Dawley , Respiración Artificial , Animales , Ratas , Sistema Glinfático/efectos de los fármacos , Sistema Glinfático/diagnóstico por imagen , Femenino , Líquido Cefalorraquídeo/efectos de los fármacos , Líquido Cefalorraquídeo/metabolismo , Anestesia/métodos , Isoflurano/farmacologíaRESUMEN
Recently developed antimigraine therapeutics targeting calcitonin gene-related peptide (CGRP) signaling are effective, though their sites of activity remain elusive. Notably, the lymphatic vasculature is responsive to CGRP signaling, but whether meningeal lymphatic vessels (MLVs) contribute to migraine pathophysiology is unknown. Mice with lymphatic vasculature deficient in the CGRP receptor (CalcrliLEC mice) treated with nitroglycerin-mediated (NTG-mediated) chronic migraine exhibit reduced pain and light avoidance compared with NTG-treated littermate controls. Gene expression profiles of lymphatic endothelial cells (LECs) isolated from the meninges of Rpl22HA/+;Lyve1Cre RiboTag mice treated with NTG revealed increased MLV-immune interactions compared with cells from untreated mice. Interestingly, the relative abundance of mucosal vascular addressin cell adhesion molecule 1-interacting (MAdCAM1-interacting) CD4+ T cells was increased in the deep cervical lymph nodes of NTG-treated control mice but not in NTG-treated CalcrliLEC mice. Treatment of cultured hLECs with CGRP peptide in vitro induced vascular endothelial-cadherin (VE-cadherin) rearrangement and reduced functional permeability. Likewise, intra cisterna magna injection of CGRP caused rearrangement of VE-cadherin, decreased MLV uptake of cerebrospinal fluid (CSF), and impaired CSF drainage in control mice but not in CalcrliLEC mice. Collectively, these findings reveal a previously unrecognized role for lymphatics in chronic migraine, whereby CGRP signaling primes MLV-immune interactions and reduces CSF efflux.
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Péptido Relacionado con Gen de Calcitonina , Meninges , Trastornos Migrañosos , Transducción de Señal , Animales , Masculino , Ratones , Péptido Relacionado con Gen de Calcitonina/metabolismo , Péptido Relacionado con Gen de Calcitonina/genética , Linfocitos T CD4-Positivos/metabolismo , Líquido Cefalorraquídeo/metabolismo , Modelos Animales de Enfermedad , Células Endoteliales/metabolismo , Inflamación/metabolismo , Vasos Linfáticos/metabolismo , Vasos Linfáticos/patología , Meninges/metabolismo , Trastornos Migrañosos/metabolismo , Trastornos Migrañosos/patología , Nitroglicerina/farmacología , Dolor/metabolismo , Receptores de Péptido Relacionado con el Gen de Calcitonina/metabolismo , Humanos , FemeninoRESUMEN
The flow of cerebrospinal fluid (CSF) along perivascular spaces (PVSs) is an important part of the brain's system for clearing metabolic waste. Astrocyte endfeet bound the PVSs of penetrating arteries, separating them from brain extracellular space. Gaps between astrocyte endfeet might provide a low-resistance pathway for fluid transport across the wall. Recent studies suggest that the astrocyte endfeet function as valves that rectify the CSF flow, producing the net flow observed in pial PVSs by changing the size of the gaps in response to pressure changes. In this study, we quantify this rectification based on three features of the PVSs: the quasi-circular geometry, the deformable endfoot wall, and the pressure oscillation inside. We provide an analytical model, based on the thin-shell hoop-stress approximation, and predict a pumping efficiency of about 0.4, which would contribute significantly to the observed flow. When we add the flow resistance of the extracellular space (ECS) to the model, we find an increased net flow during sleep, due to the known increase in ECS porosity (decreased flow resistance) compared to that in the awake state. We corroborate our analytical model with three-dimensional fluid-solid interaction simulations.
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Sistema Glinfático , Sistema Glinfático/fisiología , Encéfalo/irrigación sanguínea , Arterias/fisiología , Presión , Transporte Biológico , Líquido Cefalorraquídeo/metabolismoRESUMEN
Spinal cerebrospinal fluid-contacting neurons (CSF-cNs) form an evolutionary conserved bipolar cell population localized around the central canal of all vertebrates. CSF-cNs were shown to express molecular markers of neuronal immaturity into adulthood; however, the impact of their incomplete maturation on the chloride (Cl-) homeostasis as well as GABAergic signaling remains unknown. Using adult mice from both sexes, in situ hybridization revealed that a proportion of spinal CSF-cNs (18.3%) express the Na+-K+-Cl- cotransporter 1 (NKCC1) allowing intracellular Cl- accumulation. However, we did not find expression of the K+-Cl- cotransporter 2 (KCC2) responsible for Cl- efflux in any CSF-cNs. The lack of KCC2 expression results in low Cl- extrusion capacity in CSF-cNs under high Cl- load in whole-cell patch clamp. Using cell-attached patch clamp allowing recordings with intact intracellular Cl- concentration, we found that the activation of ionotropic GABAA receptors (GABAA-Rs) induced both depolarizing and hyperpolarizing responses in CSF-cNs. Moreover, depolarizing GABA responses can drive action potentials as well as intracellular calcium elevations by activating voltage-gated calcium channels. Blocking NKCC1 with bumetanide inhibited the GABA-induced calcium transients in CSF-cNs. Finally, we show that metabotropic GABAB receptors have no hyperpolarizing action on spinal CSF-cNs as their activation with baclofen did not mediate outward K+ currents, presumably due to the lack of expression of G-protein-coupled inwardly rectifying potassium (GIRK) channels. Together, these findings outline subpopulations of spinal CSF-cNs expressing inhibitory or excitatory GABAA-R signaling. Excitatory GABA may promote the maturation and integration of young CSF-cNs into the existing spinal circuit.
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Miembro 2 de la Familia de Transportadores de Soluto 12 , Médula Espinal , Simportadores , Animales , Ratones , Médula Espinal/metabolismo , Femenino , Masculino , Miembro 2 de la Familia de Transportadores de Soluto 12/metabolismo , Simportadores/metabolismo , Cotransportadores de K Cl , Transducción de Señal/fisiología , Neuronas/metabolismo , Neuronas/fisiología , Ácido gamma-Aminobutírico/metabolismo , Líquido Cefalorraquídeo/metabolismo , Líquido Cefalorraquídeo/fisiología , Ratones Endogámicos C57BL , Receptores de GABA-A/metabolismo , Cloruros/metabolismo , Cloruros/líquido cefalorraquídeo , Cloruros/farmacología , Neuronas GABAérgicas/metabolismo , Neuronas GABAérgicas/fisiologíaRESUMEN
BACKGROUND: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has gained prominence recently. Clinical studies have explored tDCS as an adjunct to neurologic disease rehabilitation, with evidence suggesting its potential in modulating brain clearance mechanisms. The glymphatic system, a proposed brain waste clearance system, posits that cerebrospinal fluid-interstitial fluid (CSF-ISF) exchange aids in efficient metabolic waste removal. While some studies have linked tDCS to astrocytic inositol trisphosphate (IP3)/Ca2+ signaling, the impact of tDCS on CSF-ISF exchange dynamics remains unclear. HYPOTHESIS: tDCS influences the dynamics of CSF-ISF exchange through astrocytic IP3/Ca2+ signaling. METHODS: In this study, we administered tDCS (0.1 mA for 10 min) to C57BL/6N mice anesthetized with ketamine-xylazine (KX). The anode was positioned on the cranial bone above the cortex, and the cathode was inserted into the neck. Following tDCS, we directly assessed brain fluid dynamics by injecting biotinylated dextran amine (BDA) as a CSF tracer into the cisterna magna (CM). The brain was then extracted after either 30 or 60 min and fixed. After 24 h, the sectioned brain slices were stained with Alexa 594-conjugated streptavidin (SA) to visualize BDA using immunohistochemistry. We conducted Electroencephalography (EEG) recordings and aquaporin 4 (AQP4)/CD31 immunostaining to investigate the underlying mechanisms of tDCS. Additionally, we monitored the efflux of Evans blue, injected into the cisterna magna, using cervical lymph node imaging. Some experiments were subsequently repeated with inositol trisphosphate receptor type 2 (IP3R2) knockout (KO) mice. RESULTS: Post-tDCS, we observed an increased CSF tracer influx, indicating a modulation of CSF-ISF exchange by tDCS. Additionally, tDCS appeared to enhance the brain's metabolic waste efflux. EEG recordings showed an increase in delta wave post-tDCS. But no significant change in AQP4 expression was detected 30 min post-tDCS. Besides, we found no alteration in CSF-ISF exchange and delta wave activity in IP3R2 KO mice after tDCS. CONCLUSION: Our findings suggest that tDCS augments the glymphatic system's influx and efflux. Through astrocytic IP3/Ca2+ signaling, tDCS was found to modify the delta wave, which correlates positively with brain clearance. This study underscores the potential of tDCS in modulating brain metabolic waste clearance.
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Encéfalo , Líquido Extracelular , Ratones Endogámicos C57BL , Estimulación Transcraneal de Corriente Directa , Animales , Estimulación Transcraneal de Corriente Directa/métodos , Ratones , Encéfalo/fisiología , Encéfalo/metabolismo , Líquido Extracelular/fisiología , Líquido Extracelular/metabolismo , Masculino , Sistema Glinfático/fisiología , Líquido Cefalorraquídeo/fisiología , Líquido Cefalorraquídeo/metabolismo , Astrocitos/fisiología , Astrocitos/metabolismoRESUMEN
BACKGROUND: Knowledge regarding CNS pharmacokinetics of moxifloxacin is limited, with unknown consequences for patients with meningitis caused by bacteria resistant to beta-lactams or caused by TB. OBJECTIVE: (i) To develop a novel porcine model for continuous investigation of moxifloxacin concentrations within brain extracellular fluid (ECF), CSF and plasma using microdialysis, and (ii) to compare these findings to the pharmacokinetic/pharmacodynamic (PK/PD) target against TB. METHODS: Six female pigs received an intravenous single dose of moxifloxacin (6â mg/kg) similar to the current oral treatment against TB. Subsequently, moxifloxacin concentrations were determined by microdialysis within five compartments: brain ECF (cortical and subcortical) and CSF (ventricular, cisternal and lumbar) for the following 8 hours. Data were compared to simultaneously obtained plasma samples. Chemical analysis was performed by high pressure liquid chromatography with mass spectrometry. The applied PK/PD target was defined as a maximum drug concentration (Cmax):MIC ratio >8. RESULTS: We present a novel porcine model for continuous in vivo CNS pharmacokinetics for moxifloxacin. Cmax and AUC0-8h within brain ECF were significantly lower compared to plasma and lumbar CSF, but insignificantly different compared to ventricular and cisternal CSF. Unbound Cmax:MIC ratio across all investigated compartments ranged from 1.9 to 4.3. CONCLUSION: A single dose of weight-adjusted moxifloxacin administered intravenously did not achieve adequate target site concentrations within the uninflamed porcine brain ECF and CSF to reach the applied TB CNS target.
Asunto(s)
Encéfalo , Líquido Extracelular , Microdiálisis , Moxifloxacino , Animales , Moxifloxacino/farmacocinética , Moxifloxacino/administración & dosificación , Porcinos , Femenino , Líquido Extracelular/química , Líquido Extracelular/metabolismo , Encéfalo/metabolismo , Líquido Cefalorraquídeo/química , Líquido Cefalorraquídeo/metabolismo , Antibacterianos/farmacocinética , Antibacterianos/líquido cefalorraquídeo , Antibacterianos/administración & dosificación , Antibacterianos/sangre , Plasma/química , Fluoroquinolonas/farmacocinética , Fluoroquinolonas/líquido cefalorraquídeo , Fluoroquinolonas/administración & dosificación , Fluoroquinolonas/sangre , Modelos Animales , Cromatografía Líquida de Alta Presión , Administración Intravenosa , Espectrometría de Masas , Pruebas de Sensibilidad MicrobianaRESUMEN
Over the last decade, it has become evident that cerebrospinal fluid (CSF) plays a pivotal role in brain solute clearance through perivascular pathways and interactions between the brain and meningeal lymphatic vessels. Whereas most of this fundamental knowledge was gained from rodent models, human brain clearance imaging has provided important insights into the human system and highlighted the existence of important interspecies differences. Current gold standard techniques for human brain clearance imaging involve the injection of gadolinium-based contrast agents and monitoring their distribution and clearance over a period from a few hours up to 2 days. With both intrathecal and intravenous injections being used, which each have their own specific routes of distribution and thus clearance of contrast agent, a clear understanding of the kinetics associated with both approaches, and especially the differences between them, is needed to properly interpret the results. Because it is known that intrathecally injected contrast agent reaches the blood, albeit in small concentrations, and that similarly some of the intravenously injected agent can be detected in CSF, both pathways are connected and will, in theory, reach the same compartments. However, because of clear differences in relative enhancement patterns, both injection approaches will result in varying sensitivities for assessment of different subparts of the brain clearance system. In this opinion review article, the "EU Joint Programme - Neurodegenerative Disease Research (JPND)" consortium on human brain clearance imaging provides an overview of contrast agent pharmacokinetics in vivo following intrathecal and intravenous injections and what typical concentrations and concentration-time curves should be expected. This can be the basis for optimizing and interpreting contrast-enhanced MRI for brain clearance imaging. Furthermore, this can shed light on how molecules may exchange between blood, brain, and CSF.