Neurons In Central Nervous System Research Articles

Clinical Observation of Hemodynamic and Cerebral Protective Effects of Different Doses of Dexmedetomidine in Patients with Traumatic Brain Injury

Background: Patients with craniocerebral trauma may suffer ischemic brain injury and neurological dysfunction due to immune inflammation and neuroendocrine reactions. Dexmedetomidine (Dex) is one of the commonly used anesthetic drugs in clinic. Studies have shown Dex has the function of protecting brain nerves and inhibiting inflammation. However, there are few studies on the effects of different doses of dexmedetomidine on patients undergoing surgery. The purpose of this study is to observe the effects of different doses of Dex on hemodynamics and brain protection in patients undergoing brain trauma surgery. Materials and Methods: Eighty patients with craniocerebral trauma surgery were randomly divided into study group (group A, n = 40) and control group (group B, n = 40) by random number table method. Dex pump volume was 0.5 μg/kg/h in group A and 1.0 μg/kg/h in group B. Heart rate (HR) and mean arterial pressure (MAP) were recorded before anesthesia induction (T0), immediately after endotracheal intubation (T1) and at the end of operation (T2). The serum levels of central nervous system specific protein (S-100β) and neuron specific enolase (NSE) were measured and compared between the two groups at T0 and T2. Results: HR and MAP in group A were significantly higher than those in group B at T2, and the difference was statistically significant (P P β and NSE in both groups at T2 were lower than those at T0, and the concentrations of S-100β and NSE in group A were significantly lower than those in group B at T2 (P < 0.05). Conclusions: 0.5 μg/kg dose of Dex is stable in hemodynamics and has a better protective effect on brain function in patients with traumatic brain injury.

Putting PLX5622 into perspective: microglia in central nervous system viral infection.

Putting PLX5622 into perspective: microglia in central nervous system viral infection.

Morphological characteristics of Neural Tissue and Corazonin Neurons of Central Nervous System in Larval Stage of Scuttle Fly

Morphological characteristics of Neural Tissue and Corazonin Neurons of Central Nervous System in Larval Stage of Scuttle Fly

DYRK3 phosphorylates SNAPIN to regulate axonal retrograde transport and neurotransmitter release

Among the five members of the dual-specificity tyrosine-phosphorylation-regulated kinase (DYRK) family, the cellular functions of DYRK3 have not been fully elucidated. Some studies have indicated limited physiological roles and substrates of DYRK3, including promotion of glioblastoma, requirement in influenza virus replication, and coupling of stress granule condensation with mammalian target of rapamycin complex 1 signaling. Here, we demonstrate that serum deprivation causes a decrease in intracellular DYRK3 levels via the proteolytic autophagy pathway, as well as the suppression of DYRK3 gene expression. To further demonstrate how DYRK3 affects cell viability, especially in neurons, we used a yeast two-hybrid assay and identified multiple DYRK3-binding proteins, including SNAPIN, a SNARE-associated protein implicated in synaptic transmission. We also found that DYRK3 directly phosphorylates SNAPIN at the threonine (Thr) 14 residue, increasing the interaction of SNAPIN with other proteins such as dynein and synaptotagmin-1. In central nervous system neurons, SNAPIN is associated with and mediate the retrograde axonal transport of diverse cellular products from the distal axon terminal to the soma and the synaptic release of neurotransmitters, respectively. Moreover, phosphorylation of SNAPIN at Thr-14 was found to positively modulate mitochondrial retrograde transport in mouse cortical neurons and the recycling pool size of synaptic vesicles, contributing to neuronal viability. In conclusion, the present study demonstrates that DYRK3 phosphorylates SNAPIN, positively regulating the dynein-mediated retrograde transport of mitochondria and SNARE complex-mediated exocytosis of synaptic vesicles within the neurons. This finding further suggests that DYRK3 affects cell viability and provides a novel neuroprotective mechanism.

Mating disrupts morning anticipation in Drosophila melanogaster females.

After mating, the physiology of Drosophila females undergo several important changes, some of which are reflected in their rest-activity cycles. To explore the hypothesis that mating modifies the temporal organization of locomotor activity patterns, we recorded fly activity by a video tracking method. Monitoring rest-activity patterns under light/dark (LD) cycles indicated that mated females lose their ability to anticipate the night-day transition, in stark contrast to males and virgins. This postmating response is mediated by the activation of the sex peptide receptor (SPR) mainly on pickpocket (ppk) expressing neurons, since reducing expression of this receptor in these neurons restores the ability to anticipate the LD transition in mated females. Furthermore, we provide evidence of connectivity between ppk+ neurons and the pigment-dispersing factor (PDF)-positive ventral lateral neurons (sLNv), which play a central role in the temporal organization of daily activity. Since PDF has been associated to the generation of the morning activity peak, we hypothesized that the mating signal could modulate PDF levels. Indeed, we confirm that mated females have reduced PDF levels at the dorsal protocerebrum; moreover, SPR downregulation in ppk+ neurons mimics PDF levels observed in males. In sum, our results are consistent with a model whereby mating-triggered signals reach clock neurons in the fly central nervous system to modulate the temporal organization of circadian behavior according to the needs of the new status.

Modeling Brain Vasculature Immune Interactions In Vitro.

The endothelial blood-brain barrier (BBB) protects central nervous system (CNS) neurons from the changeable milieu of the bloodstream by strictly controlling the movement of molecules and immune cells between the blood and the CNS. Immune cell migration across the vascular wall is a multistep process regulated by the sequential interaction of different signaling and adhesion molecules on the endothelium and the immune cells. Accounting for its unique barrier properties and trafficking molecule expression profile, particular adaptions in immune cell migration across the BBB have been observed. Thus, in vitro models of the BBB are desirable to explore the precise cellular and molecular mechanisms involved in immune cell trafficking across the BBB. The challenge to overcome is that barrier properties of brain microvascular endothelial cells are not intrinsic and readily lost in culture. With a focus on human in vitro BBB models, we here discuss the suitability of available in vitro models for the BBB for exploring the specific mechanisms involved in immune cell trafficking across the BBB.

MOLECULAR MECHANISMS DEFINING APPLICATION OF GLYCINE AND ZINC COMBINATIONIN CORRECTION OF STRESS AND ANXIETY MAIN MANIFESTATIONS

The aim of the work was to carry out a systematic analysis of the molecular mechanisms that determine the possibility of a combined use of amino acid glycine and zinc compounds for the treatment of patients with manifestations of stress and anxiety.Materials and methods. Information retrieval (Scopus, PubMed) and library (eLibrary) databases were used as research tools. In some cases, the ResearchGate application was applied for a semantic search. The analysis and generalization of references was carried out on the research topic, covering the period from 2000 to the present time.Results. It has been shown that amino acid glycine, along with gamma-aminobutyric acid (GABA), is a key neurotransmitter that regulates physiological inhibition processes in the central nervous system (CNS) by increasing transmembrane conductance in specific pentameric ligand-gated ion channels. The introduction of zinc ions can potentiate the opening of these receptors by increasing their affinity for glycine, resulting in an inhibitory processes increase in CNS neurons. The replenishment of the glycine and zinc combined deficiency is an important element in the correction of a post-stress dysfunction of the central nervous system. A balanced intake of zinc and glycine is essential for most people who experience daily effects of multiple stresses and anxiety. This combination is especially useful for the people experiencing a state of chronic psycho-emotional stress and maladaptation, including those who have a difficulty in falling asleep.Conclusion. A balanced maintenance of the zinc and glycine concentration in the body of a healthy person leads to the development of a stable anti-anxiety effect, which is accompanied by the normalization of the sleep-wake rhythm, which makes it possible to have a good rest without any loss of working efficiency after waking up.

Circadian time- and sleep-dependent modulation of cortical parvalbumin-positive inhibitory neurons.

Parvalbumin-positive neurons (PVs) are the main class of inhibitory neurons in the mammalian central nervous system. By examining diurnal changes in synaptic and neuronal activity of PVs in the supragranular layer of the mouse primary visual cortex (V1), we found that both PV input and output are modulated in a time- and sleep-dependent manner throughout the 24-h day. We first show that PV-evoked inhibition is stronger by the end of the light cycle (ZT12) relative to the end of the dark cycle (ZT0), which is in line with the lower inhibitory input of PV neurons at ZT12 than at ZT0. Interestingly, PV inhibitory and excitatory synaptic transmission slowly oscillate in opposite directions during the light/dark cycle. Although excitatory synapses are predominantly regulated by experience, inhibitory synapses are regulated by sleep, via acetylcholine activating M1 receptors. Consistent with synaptic regulation of PVs, we further show invivo that spontaneous PV activity displays daily rhythm mainly determined by visual experience, which negatively correlates with the activity cycle of surrounding pyramidal neurons and the dorsal lateral geniculate nucleus-evoked responses in V1. These findings underscore the physiological significance of PV's daily modulation.

The Role of Epigenetics in Neuroinflammatory-Driven Diseases

Neurodegenerative disorders are characterized by the progressive loss of central and/or peripheral nervous system neurons. Within this context, neuroinflammation comes up as one of the main factors linked to neurodegeneration progression. In fact, neuroinflammation has been recognized as an outstanding factor for Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple sclerosis (MS). Interestingly, neuroinflammatory diseases are characterized by dramatic changes in the epigenetic profile, which might provide novel prognostic and therapeutic factors towards neuroinflammatory treatment. Deep changes in DNA and histone methylation, along with histone acetylation and altered non-coding RNA expression, have been reported at the onset of inflammatory diseases. The aim of this work is to review the current knowledge on this field.

Proper wiring of newborn neurons to control bladder function after complete spinal cord injury

Activation of endogenous neurogenesis by bioactive materials enables restoration of sensory/motor function after complete spinal cord injury (SCI) via formation of new relay neural circuits. The underlying wiring logic of newborn neurons in adult central nervous system (CNS) is unknown. Here, we report neurotrophin3-loaded chitosan biomaterial substantially recovered bladder function after SCI. Multiple neuro-circuitry tracing technologies using pseudorabies virus (PRV), rabies virus (RV), and anterograde adeno-associated virus (AAV), demonstrated that newborn neurons were integrated into the micturition neural circuits and reconnected higher brain centers and lower spinal cord centers to control voiding, and participated in the restoration of the lower urinary tract function, even in the absence of long-distance axonal regeneration. Opto- and chemo-genetic studies further supported the notion that the supraspinal control of the lower urinary tract function was partially recovered. Our data demonstrated that regenerated relay neurons could be properly integrated into disrupted long-range neural circuits to restore function of adult CNS.

The implication of a diversity of non-neuronal cells in disorders affecting brain networks.

In the central nervous system (CNS) neurons are classically considered the functional unit of the brain. Analysis of the physical connections and co-activation of neurons, referred to as structural and functional connectivity, respectively, is a metric used to understand their interplay at a higher level. A myriad of glial cell types throughout the brain composed of microglia, astrocytes and oligodendrocytes are key players in the maintenance and regulation of neuronal network dynamics. Microglia are the central immune cells of the CNS, able to affect neuronal populations in number and connectivity, allowing for maturation and plasticity of the CNS. Microglia and astrocytes are part of the neurovascular unit, and together they are essential to protect and supply nutrients to the CNS. Oligodendrocytes are known for their canonical role in axonal myelination, but also contribute, with microglia and astrocytes, to CNS energy metabolism. Glial cells can achieve this variety of roles because of their heterogeneous populations comprised of different states. The neuroglial relationship can be compromised in various manners in case of pathologies affecting development and plasticity of the CNS, but also consciousness and mood. This review covers structural and functional connectivity alterations in schizophrenia, major depressive disorder, and disorder of consciousness, as well as their correlation with vascular connectivity. These networks are further explored at the cellular scale by integrating the role of glial cell diversity across the CNS to explain how these networks are affected in pathology.

Wireless neuromodulation in vitro and in vivo by intrinsic TRPC-mediated magnetomechanical stimulation

Various magnetic deep brain stimulation (DBS) methods have been developing rapidly in the last decade for minimizing the invasiveness of DBS. However, current magnetic DBS methods, such as magnetothermal and magnetomechanical stimulation, require overexpressing exogeneous ion channels in the central nervous system (CNS). It is unclear whether magnetomechanical stimulation can modulate non-transgenic CNS neurons or not. Here, we reveal that the torque of magnetic nanodiscs with weak and slow alternative magnetic field (50 mT at 10 Hz) could activate neurons through the intrinsic transient receptor potential canonical channels (TRPC), which are mechanosensitive ion channels widely expressed in the brain. The immunostaining with c-fos shows the increasement of neuronal activity by wireless DBS with magnetomechanical approach in vivo. Overall, this research demonstrates a magnetic nanodiscs-based magnetomechanical approach that can be used for wireless neuronal stimulation in vitro and untethered DBS in vivo without implants or genetic manipulation.

RF15 | PMON305 Membrane Progesterone Receptor α (mPRα/PAQR7) Promotes Survival and Axonal Sprouting in Human Neuronal Cells Lines Through Direct and Human Schwann-Cell Like Differentiated Adipose Stem Cells-Mediated Mechanisms

Abstract Injuries to peripheral nerves affect millions of people worldwide. These injuries can be significantly detrimental to the patients’ quality of life. While central nervous system neurons have extremely limited regenerative potential, peripheral nerves are able to regenerate after injury. However, this regeneration process often leads to unsatisfactory regenerative outcomes. Improving peripheral nerve regeneration is therefore a strong medical need. Schwann cells, the glial myelinating cells of the peripheral nervous system, are known to play an important role in promoting peripheral nerve regeneration. However, their limited in vitro expansion capability and limited availability has led several research groups to investigate the possibility of using differentiated stem cells as a potential tool to promote nerve regeneration, in association with other tools such biomaterial tubes. The activation of membrane progesterone receptor α (mPRα, PAQR7) with the selective agonist 19-ethenyl-progesterone (02-0) was recently shown to elicit potentially pro-regenerative effects in a model of human Schwann cell-like (SCL) differentiated adipose stem cells (ASC). Indeed, mPRα activation led to increased SCL-ASC migration, proliferation and neurotrophin (specifically BDNF) release. All these outcomes are expected to be beneficial for nerve regeneration. In this project, we investigated the effect of mPRα activation in SCL-ASC on neuronal cell lines to demonstrate that the positive effects previously observed in SCL-ASC have a beneficial effect in neuronal cells. We first investigated how the conditioned medium of untreated SCL-ASC (CM-) and SCL-ASC treated with the selective mPR agonist 02-0 (CM+) affected cell survival and neuronal sprouting in two different neuronal cell lines, IMR-32 and SH-SY-5Y. In both cases, CM- had a beneficial effect, reducing cell death, as assessed in starvation experiments, and promoting axonal sprouting, with the presence of longer cell processes in the two cell models compared to control. In both cases, CM+ had an even stronger effect than CM-, suggesting that mPRα activation may lead to the release of specific molecules that promote nerve regeneration. Moreover, CM- and CM+ treatments were effective in increasing the gene expression of selected peripheral regeneration markers (CREB3, ATF3 and GAP46) in SH-SY-5Y cells. Since mPR receptors are present in neuronal cells, we performed another series of cell death and axonal sprouting experiments in SH-SY-5Y6 cells, comparing CM- and CM+ effects to an experimental group in which 02-0 was added to CM- after incubation with SCL-ASC. These experiments showed that the effect on cell death was mostly due to direct activation of mPR receptors in neuronal cells. On the other hand, the effect on axonal sprouting depended on mPRα activation in SCL-ASC and subsequent release of active molecules in the medium. Our results support the hypothesis that mPRα activation in SCL-ASC may represent a promising pharmacological target to promote peripheral nerve regeneration. Presentation: Sunday, June 12, 2022 12:42 p.m. - 12:47 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

A small molecule M1 promotes optic nerve regeneration to restore target-specific neural activity and visual function

Axon regeneration is an energy-demanding process that requires active mitochondrial transport. In contrast to the central nervous system (CNS), axonal mitochondrial transport in regenerating axons of the peripheral nervous system (PNS) increases within hours and sustains for weeks after injury. Yet, little is known about targeting mitochondria in nervous system repair. Here, we report the induction of sustained axon regeneration, neural activities in the superior colliculus (SC), and visual function recovery after optic nerve crush (ONC) by M1, a small molecule that promotes mitochondrial fusion and transport. We demonstrated that M1 enhanced mitochondrial dynamics in cultured neurons and accelerated invivo axon regeneration in the PNS. Ex vivo time-lapse imaging and kymograph analysis showed that M1 greatly increased mitochondrial length, axonal mitochondrial motility, and transport velocity in peripheral axons of the sciatic nerves. Following ONC, M1 increased the number of axons regenerating through the optic chiasm into multiple subcortical areas and promoted the recovery of local field potentials in the SC after optogenetic stimulation of retinal ganglion cells, resulting in complete recovery of the pupillary light reflex, and restoration of the response to looming visual stimuli was detected. M1 increased the gene expression of mitochondrial fusion proteins and major axonal transport machinery in both the PNS and CNS neurons without inducing inflammatory responses. The knockdown of two key mitochondrial genes, Opa1 or Mfn2, abolished the growth-promoting effects of M1 after ONC, suggesting that maintaining a highly dynamic mitochondrial population in axons is required for successful CNS axon regeneration.

Microfluidic devices as model platforms of CNS injury-ischemia to study axonal regeneration by regulating mitochondrial transport and bioenergetic metabolism

Central nervous system (CNS) neurons typically fail to regenerate their axons after injury leading to neurological impairment. Axonal regeneration is a highly energy-demanding cellular program that requires local mitochondria to supply most energy within injured axons. Recent emerging lines of evidence have started to reveal that injury-triggered acute mitochondrial damage and local energy crisis contribute to the intrinsic energetic restriction that accounts for axon regeneration failure in the CNS. Characterizing and reprogramming bioenergetic signaling and mitochondrial maintenance after axon injury-ischemia is fundamental for developing therapeutic strategies that can restore local energy metabolism and thus facilitate axon regeneration. Therefore, establishing reliable and reproducible neuronal model platforms is critical for assessing axonal energetic metabolism and regeneration capacity after injury-ischemia. In this focused methodology article, we discuss recent advances in applying cutting-edge microfluidic chamber devices in combination with state-of-the-art live-neuron imaging tools to monitor axonal regeneration, mitochondrial transport, bioenergetic metabolism, and local protein synthesis in response to injury-ischemic stress in mature CNS neurons.

Computational models reveal how chloride dynamics determine the optimal distribution of inhibitory synapses to minimise dendritic excitability.

Many neurons in the mammalian central nervous system have complex dendritic arborisations and active dendritic conductances that enable these cells to perform sophisticated computations. How dendritically targeted inhibition affects local dendritic excitability is not fully understood. Here we use computational models of branched dendrites to investigate where GABAergic synapses should be placed to minimise dendritic excitability over time. To do so, we formulate a metric we term the "Inhibitory Level" (IL), which quantifies the effectiveness of synaptic inhibition for reducing the depolarising effect of nearby excitatory input. GABAergic synaptic inhibition is dependent on the reversal potential for GABAA receptors (EGABA), which is primarily set by the transmembrane chloride ion (Cl-) concentration gradient. We, therefore, investigated how variable EGABA and dynamic chloride affects dendritic inhibition. We found that the inhibitory effectiveness of dendritic GABAergic synapses combines at an encircled branch junction. The extent of this inhibitory accumulation is dependent on the number of branches and location of synapses but is independent of EGABA. This inhibitory accumulation occurs even for very distally placed inhibitory synapses when they are hyperpolarising-but not when they are shunting. When accounting for Cl- fluxes and dynamics in Cl- concentration, we observed that Cl- loading is detrimental to inhibitory effectiveness. This enabled us to determine the most inhibitory distribution of GABAergic synapses which is close to-but not at-a shared branch junction. This distribution balances a trade-off between a stronger combined inhibitory influence when synapses closely encircle a branch junction with the deleterious effects of increased Cl- by loading that occurs when inhibitory synapses are co-located.

Electrical, Electromagnetic, Ultrasound Wave Therapies, and Electronic Implants for Neuronal Rejuvenation, Neuroprotection, Axonal Regeneration, and IOP Reduction.

The peripheral nervous system (PNS) of mammals and nervous systems of lower organisms possess significant regenerative potential. In contrast, although neural plasticity can provide some compensation, the central nervous system (CNS) neurons and nerves of adult mammals generally fail to regenerate after an injury or damage. However, use of diverse electrical, electromagnetic and sonographic energy waves are illuminating novel ways to stimulate neuronal differentiation, proliferation, neurite growth, and axonal elongation/regeneration leading to various levels of functional recovery in animals and humans afflicted with disorders of the CNS, PNS, retina, and optic nerve. Tools such as acupuncture, electroacupuncture, electroshock therapy, electrical stimulation, transcranial magnetic stimulation, red light therapy, and low-intensity pulsed ultrasound therapy are demonstrating efficacy in treating many different maladies. These include wound healing, partial recovery from motor dysfunctions, recovery from ischemic/reperfusion insults and CNS and ocular remyelination, retinal ganglion cell (RGC) rejuvenation, and RGC axonal regeneration. Neural rejuvenation and axonal growth/regeneration processes involve activation or intensifying of the intrinsic bioelectric waves (action potentials) that exist in every neuronal circuit of the body. In addition, reparative factors released at the nerve terminals and via neuronal dendrites (transmitter substances), extracellular vesicles containing microRNAs and neurotrophins, and intercellular communication occurring via nanotubes aid in reestablishing lost or damaged connections between the traumatized tissues and the PNS and CNS. Many other beneficial effects of the aforementioned treatment paradigms are mediated via gene expression alterations such as downregulation of inflammatory and death-signal genes and upregulation of neuroprotective and cytoprotective genes. These varied techniques and technologies will be described and discussed covering cell-based and animal model-based studies. Data from clinical applications and linkage to human ocular diseases will also be discussed where relevant translational research has been reported.

Targeting APC-Host Microbe interactions 2Robust control of a neurotropic parasite through MHC I presentation by infected neurons

Control of Central Nervous System (CNS) pathogens by CD8 T cells is pivotal to avoid fatal neuroinflammation. Yet the modalities of MHC I presentation in the brain are poorly understood. We analyzed the antigen presentation mechanisms underlying CD8 T cell-mediated brain restriction of Toxoplasma gondii, a neurotropic parasite that can chronically reside as cysts in the CNS and cause deadly encephalitis. First we engineered transgenic parasites expressing a model antigen that allows the establishment of latent toxoplasmosis in C57BL/6 mice, a mouse model that normally develops encephalitis following T. gondii infection. We show that MHC I presentation of that model antigen suffices to prevent encephalitis, even when restricted to the rapidly dividing tachyzoite stage. We find that improper parasite control in the context of encephalitis correlates with suboptimal MHC I presentation of T. gondii antigens by primary neuronal cultures. Using a new model of conditional MHC I-deficient mice, we finally demonstrate that brain parasite control requires neuronal MHC I presentation. Thus, MHC I presentation by CNS neurons is a crucial checkpoint that determines the clinical outcome of a prevalent and persisting brain infection.

Immunosenescence and Multiple Sclerosis: A Literature Review

Introduction: Multiple sclerosis is a chronic inflammatory disorder characterized by the demyelination of central nervous system neurons, giving rise to various motor and non-motor impairments. Aging has been strongly associated with inflammation and immunosenescence, and it is believed that the dysfunction of regulatory T-cells is the central complication in the maintenance of peripheral immunity. CD4+ T-cells and Th17 cells seem to play a crucial role in autoimmune inflammation and are important in the pathophysiology underlying multiple sclerosis. In this systematic review, the link between aging and T-cell function will be explored as well as its implication in MS pathophysiology. Methods: A literature review was conducted using databases such as PubMed, NCBI, and Scopus. Relevant primary literature describing theories or results of an experiment and review papers were selected. Data from primary articles were analyzed to explore the association between aging and MS, as well as its contribution to immunosenescence. Results: There exists a strong association between aging and the pathophysiology of MS which was suggested by a multitude of laboratory studies. Animal models of experimental autoimmune encephalomyelitis have demonstrated the immunological mechanisms of this disease by highlighting differences in T-cell presence and function in healthy people versus MS patients. Discussion: According to numerous studies, chronic inflammation is recognized as a sign of aging, rendering it one of the key contributors to neurodegenerative diseases like MS. The implication of regulatory T-cells in MS is crucial due to its necessity for the maintenance of immunosuppressive activity, which has been found to deteriorate with age. Myelin antigens supplied by microglial cells reactivate autoreactive CD4+ T-cells infiltrating the CNS, producing a cascade of immunological responses that lead to demyelination and tissue death. Conclusion: This literature review finds that MS is largely T-cell mediated and that the aging process heightens chronic inflammation, leading to the destruction of neurons in the CNS.

Targetability of the neurovascular unit in inflammatory diseases of the central nervous system.

The blood-brain barrier (BBB) is a selectively permeable barrier separating the periphery from the central nervous system (CNS). The BBB restricts the flow of most material into and out of the CNS, including many drugs that could be used as potent therapies. BBB permeability is modulated by several cells that are collectively called the neurovascular unit (NVU). The NVU consists of specialized CNS endothelial cells (ECs), pericytes, astrocytes, microglia, and neurons. CNS ECs maintain a complex "seal" via tight junctions, forming the BBB; breakdown of these tight junctions leads to BBB disruption. Pericytes control the vascular flow within capillaries and help maintain the basal lamina. Astrocytes control much of the flow of material that has moved beyond the CNS EC layer and can form a secondary barrier under inflammatory conditions. Microglia survey the border of the NVU for noxious material. Neuronal activity also plays a role in the maintenance of the BBB. Since astrocytes, pericytes, microglia, and neurons are all able to modulate the permeability of the BBB, understating the complex contributions of each member of the NVU will potentially uncover novel and effective methods for delivery of neurotherapies to the CNS.