scholarly journals On the existence of mechanoreceptors within the neurovascular unit of the rodent and rabbit brain

2018 ◽  
Author(s):  
Jorge Larriva-Sahd ◽  
Martha León-Olea ◽  
Víctor Vargas-Barroso ◽  
Alfredo Varela-Echavarría ◽  
Luis Concha
Keyword(s):  
Neurovascular Unit ◽  
Unmyelinated Axon ◽  
Mammalian Brain ◽  
Rabbit Brain ◽  
Adult Rabbit ◽  
Sensory Receptor ◽  
Brain Vasculature ◽  
Arterial Blood ◽  
Strategic Location ◽  
The Brain

AbstractWe describe a set of perivascular interneurons (PINs) originating a series of fibro-vesicular complexes (FVCs) throughout the gray matter of the adult rabbit and rat brain. PINs-FVCs are ubiquitous throughout the brain vasculature as defined in Golgi-impregnated specimens. Most PINs consist of small, aspiny cells with local or long (> 1 millimeter) axons that split running with arterial blood vessels. Upon ramification, axons originate FVCs around the roots of the arising vascular branches. Distally, FVCs form paired axons that run parallel to the vessel’s wall until another ramification ensues and a new FVC is formed. This alternating pattern ceases when the capillary diameter narrows (i.e., <8 µm) and axons resolve. FVCs, as visualized by electron microscopy, consist of clusters of anastomotic perivascular bulbs (PVBs) arising from the PIN’s unmyelinated axon. PVBs lie alongside the pre- or -capillary wall, surrounded by end-feet and the extracellular matrix of endothelial cells and pericytes. A PVB contains mitochondria, multivesicular bodies, and granules with a membranous core similar to those observed in Meissner corpuscles and other mechanoreceptors. Some PVBs form asymmetrical, axo-spinous synapses with presumptive adjacent neurons. Antisera to sensory fiber-terminals co-label putative FVCs that are embedded by astrocytic end-feet. Because of the strategic location, ubiquity, and cytological organization of the PIN-FVC, it is suggested that: 1. PIN-FVCs are distributed throughout the mammalian brain vasculature. 2. The PIN-FVC is a putative sensory receptor intrinsic of the neurovascular unit. 3. The PIN-FVC may correspond to an afferent limb of the sensory-motor feed-back controlling local blood flow.

Abstract MP17: Upregulating E2F1 Mitigates Senescence-Associated Phenotypes in Cultured Primary Endothelial Cells

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Michael E Maniskas ◽  
Yun-ju Lai ◽  
Sean P Marrelli ◽  
Louise D McCullough ◽  
Jose F Moruno-manchon
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Neurovascular Unit ◽  
Glucose Deprivation ◽  
Cerebral Hypoperfusion ◽  
Aged Mouse ◽  
Aged Mice ◽  
Brain Vasculature ◽  
Bilateral Carotid ◽  
The Brain

Vascular contributions to cognitive impairment and dementia (VCID) includes multiple disorders that are identified by cognitive deficits secondary to cerebrovascular pathology. The risk of VCID is higher in people after the age of 70, and, currently, there is no effective treatment. Vascular endothelial cells (VEC) are critical components of the brain vasculature and neurovascular unit and their health is vital to the capacity of the brain vasculature to respond to stressors. However, aged VEC may enter an irreversible replicative-arrest state (senescence), which has been associated with dementia. E2F transcription factor 1 (E2F1) regulates cell cycle progression and DNA damage repair. Importantly, E2F1 deficiency is associated with cell senescence. We hypothesized that E2F1 downregulation contributes to senescence in the cerebral endothelium during aging. We used cultured primary VEC from young (4-months old, mo) and aged (18-mo) male and female mice for RNA sequencing, plasmid-based gene delivery, high-resolution microscopy, and (4-, 12-, and 18-mo) mice of the bilateral carotid artery stenosis (BCAS) model, which produces chronic cerebral hypoperfusion and recapitulates some of the features seen in patients with VCID. We found that overexpression of E2F1 reduced the levels of senescence-associated phenotypes in cultured VEC from young mice that were exposed to oxygen and glucose deprivation (p<0.001), which induces endothelial senescence. Our RNA seq data showed that the expression of E2f1 was reduced (~40%) in cultured primary VEC from aged mouse brains compared with young cells (p<0.001). E2F1 levels were reduced in the brains of aged mice. Interestingly, we found sex differences in E2F1 levels, with less protein levels (~30%) in males vs females (p<0.05), independently of age. Also, aged BCAS mice (1 month after surgery) had more severe senescence phenotypes, reduced cerebral blood flow, and worse memory deficits compared with control mice (p<0.05). The effect of BCAS was more prominent in aged mice compared with younger (4- and 12-mo) mice. In conclusion , our study identifies E2F1 as a potential regulator of endothelial senescence in mice and highlights the contribution of aging as an important factor in losing endothelial resilience.

scholarly journals Impact of Tau on Neurovascular Pathology in Alzheimer's Disease

2021 ◽  
Vol 11 ◽  
Author(s):  
Elisa Canepa ◽  
Silvia Fossati
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Disorder ◽  
Neurovascular Unit ◽  
Amyloid Angiopathy ◽  
Brain Vasculature ◽  
Mitochondrial Alterations ◽  
Species Production ◽  
The Impact ◽  
The Brain

Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the most prevalent cause of dementia. The main cerebral histological hallmarks are represented by parenchymal insoluble deposits of amyloid beta (Aβ plaques) and neurofibrillary tangles (NFT), intracellular filamentous inclusions of tau, a microtubule-associated protein. It is well-established that cerebrovascular dysfunction is an early feature of AD pathology, but the detrimental mechanisms leading to blood vessel impairment and the associated neurovascular deregulation are not fully understood. In 90% of AD cases, Aβ deposition around the brain vasculature, known as cerebral amyloid angiopathy (CAA), alters blood brain barrier (BBB) essential functions. While the effects of vascular Aβ accumulation are better documented, the scientific community has only recently started to consider the impact of tau on neurovascular pathology in AD. Emerging compelling evidence points to transmission of neuronal tau to different brain cells, including astrocytes, as well as to the release of tau into brain interstitial fluids, which may lead to perivascular neurofibrillar tau accumulation and toxicity, affecting vessel architecture, cerebral blood flow (CBF), and vascular permeability. BBB integrity and functionality may therefore be impacted by pathological tau, consequentially accelerating the progression of the disease. Tau aggregates have also been shown to induce mitochondrial damage: it is known that tau impairs mitochondrial localization, distribution and dynamics, alters ATP and reactive oxygen species production, and compromises oxidative phosphorylation systems. In light of this previous knowledge, we postulate that tau can initiate neurovascular pathology in AD through mitochondrial dysregulation. In this review, we will explore the literature investigating tau pathology contribution to the malfunction of the brain vasculature and neurovascular unit, and its association with mitochondrial alterations and caspase activation, in cellular, animal, and human studies of AD and tauopathies.

scholarly journals Foe or friend? Janus-faces of the neurovascular unit in the formation of brain metastases

2017 ◽  
Vol 38 (4) ◽  
pp. 563-587 ◽  
Author(s):  
Imola Wilhelm ◽  
Csilla Fazakas ◽  
Kinga Molnár ◽  
Attila G Végh ◽  
János Haskó ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Endothelial Cells ◽  
Neurovascular Unit ◽  
Malignant Cells ◽  
Metastasis Formation ◽  
Primary Tumors ◽  
Brain Vasculature ◽  
Metastatic Cells ◽  
The Central Nervous System ◽  
The Brain

Despite the potential obstacle represented by the blood–brain barrier for extravasating malignant cells, metastases are more frequent than primary tumors in the central nervous system. Not only tightly interconnected endothelial cells can hinder metastasis formation, other cells of the brain microenvironment (like astrocytes and microglia) can also be very hostile, destroying the large majority of metastatic cells. However, malignant cells that are able to overcome these harmful mechanisms may benefit from the shielding and even support provided by cerebral endothelial cells, astrocytes and microglia, rendering the brain a sanctuary site against anti-tumor strategies. Thus, cells of the neurovascular unit have a Janus-faced attitude towards brain metastatic cells, being both destructive and protective. In this review, we present the main mechanisms of brain metastasis formation, including those involved in extravasation through the brain vasculature and survival in the cerebral environment.

scholarly journals Argonaute-2 protects the neurovascular unit from damage caused by systemic inflammation

2022 ◽  
Vol 19 (1) ◽  
Author(s):  
Marta Machado-Pereira ◽  
Cláudia Saraiva ◽  
Liliana Bernardino ◽  
Ana C. Cristóvão ◽  
Raquel Ferreira
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Primary Cultures ◽  
Neurovascular Unit ◽  
Brain Endothelial Cells ◽  
Neuronal Function ◽  
Nitric Oxide Release ◽  
Argonaute 2 ◽  
Brain Vasculature ◽  
The Brain

Abstract Background The brain vasculature plays a pivotal role in the inflammatory process by modulating the interaction between blood cells and the neurovascular unit. Argonaute-2 (Ago2) has been suggested as essential for endothelial survival but its role in the brain vasculature or in the endothelial–glial crosstalk has not been addressed. Thus, our aim was to clarify the significance of Ago2 in the inflammatory responses elicited by these cell types. Methods Mouse primary cultures of brain endothelial cells, astrocytes and microglia were used to evaluate cellular responses to the modulation of Ago2. Exposure of microglia to endothelial cell-conditioned media was used to assess the potential for in vivo studies. Adult mice were injected intraperitoneally with lipopolysaccharide (LPS) (2 mg/kg) followed by three daily intraperitoneal injections of Ago2 (0.4 nM) to assess markers of endothelial disruption, glial reactivity and neuronal function. Results Herein, we demonstrated that LPS activation disturbed the integrity of adherens junctions and downregulated Ago2 in primary brain endothelial cells. Exogenous treatment recovered intracellular Ago2 above control levels and recuperated vascular endothelial-cadherin expression, while downregulating LPS-induced nitric oxide release. Primary astrocytes did not show a significant change in Ago2 levels or response to the modulation of the Ago2 system, although endogenous Ago2 was shown to be critical in the maintenance of tumor necrosis factor-α basal levels. LPS-activated primary microglia overexpressed Ago2, and Ago2 silencing contained the inflammatory response to some extent, preventing interleukin-6 and nitric oxide release. Moreover, the secretome of Ago2-modulated brain endothelial cells had a protective effect over microglia. The intraperitoneal injection of LPS impaired blood–brain barrier and neuronal function, while triggering inflammation, and the subsequent systemic administration of Ago2 reduced or normalized endothelial, glial and neuronal markers of LPS damage. This outcome likely resulted from the direct action of Ago2 over the brain endothelium, which reestablished glial and neuronal function. Conclusions Ago2 could be regarded as a putative therapeutic agent, or target, in the recuperation of the neurovascular unit in inflammatory conditions.

The Relative Vascularity of Different Areas of the Mammalian Brain

1937 ◽  
Vol 83 (346) ◽  
pp. 510-511 ◽  
Author(s):  
A. Colin P. Campbell
Keyword(s):  
Nervous System ◽  
Basal Ganglia ◽  
Rat Brain ◽  
Cerebellar Cortex ◽  
Extensive Study ◽  
Mammalian Brain ◽  
Rabbit Brain ◽  
Human Brains ◽  
The Brain ◽  
Different Parts

Though many of the earlier workers made statements based on general impressions from injected preparations about the relative vascularity of different parts of the brain, only comparatively recently has an attempt been made to measure and express numerically the capillary development in different areas, by methods similar to those used by Krogh in studying the vascularity of muscle. Craigie has made an extensive study of the rat brain by such methods, Cobb, and Cobb and Talbot have investigated certain areas of the rabbit brain, and Dunning and Wolf certain parts of the nervous system of the cat. In the present paper a personal investigation (undertaken at the suggestion of Dr. Cobb) is reported, comparing the basal ganglia, cerebral and cerebellar cortex of the cat as regards capillary vascularity. The capillaries were demonstrated by Indian ink injection, and results expressed in millimetres of capillary per cubic millimetre of tissue. Substantiating observations were made on similar areas of monkey and human brains, but without attempting accurate measurement as in the cat material.

scholarly journals An architectonic type principle in the development of laminar patterns of cortico-cortical connections

2021 ◽  
Author(s):  
Sarah F. Beul ◽  
Alexandros Goulas ◽  
Claus C. Hilgetag
Keyword(s):  
Structural Connectivity ◽  
Macaque Monkey ◽  
Brain Regions ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Cortical Connections ◽  
Cortical Projections ◽  
Structural Connections ◽  
High Degree ◽  
The Brain

AbstractStructural connections between cortical areas form an intricate network with a high degree of specificity. Many aspects of this complex network organization in the adult mammalian cortex are captured by an architectonic type principle, which relates structural connections to the architectonic differentiation of brain regions. In particular, the laminar patterns of projection origins are a prominent feature of structural connections that varies in a graded manner with the relative architectonic differentiation of connected areas in the adult brain. Here we show that the architectonic type principle is already apparent for the laminar origins of cortico-cortical projections in the immature cortex of the macaque monkey. We find that prenatal and neonatal laminar patterns correlate with cortical architectonic differentiation, and that the relation of laminar patterns to architectonic differences between connected areas is not substantially altered by the complete loss of visual input. Moreover, we find that the degree of change in laminar patterns that projections undergo during development varies in proportion to the relative architectonic differentiation of the connected areas. Hence, it appears that initial biases in laminar projection patterns become progressively strengthened by later developmental processes. These findings suggest that early neurogenetic processes during the formation of the brain are sufficient to establish the characteristic laminar projection patterns. This conclusion is in line with previously suggested mechanistic explanations underlying the emergence of the architectonic type principle and provides further constraints for exploring the fundamental factors that shape structural connectivity in the mammalian brain.

scholarly journals Modeling temperature- and Cav3 subtype-dependent alterations in T-type calcium channel mediated burst firing

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Fernando R. Fernandez ◽  
Mircea C. Iftinca ◽  
Gerald W. Zamponi ◽  
Ray W. Turner
Keyword(s):  
Calcium Channel ◽  
Neuronal Excitability ◽  
Neuronal Firing ◽  
Mammalian Brain ◽  
Peripheral Tissues ◽  
Window Current ◽  
Modeling Data ◽  
The Brain ◽  
Firing Neuron ◽  
Cav3 Channel

AbstractT-type calcium channels are important regulators of neuronal excitability. The mammalian brain expresses three T-type channel isoforms (Cav3.1, Cav3.2 and Cav3.3) with distinct biophysical properties that are critically regulated by temperature. Here, we test the effects of how temperature affects spike output in a reduced firing neuron model expressing specific Cav3 channel isoforms. The modeling data revealed only a minimal effect on baseline spontaneous firing near rest, but a dramatic increase in rebound burst discharge frequency for Cav3.1 compared to Cav3.2 or Cav3.3 due to differences in window current or activation/recovery time constants. The reduced response by Cav3.2 could optimize its activity where it is expressed in peripheral tissues more subject to temperature variations than Cav3.1 or Cav3.3 channels expressed prominently in the brain. These tests thus reveal that aspects of neuronal firing behavior are critically dependent on both temperature and T-type calcium channel subtype.

scholarly journals Mesenchymal Stem Cell Derived Extracellular Vesicles for Repairing the Neurovascular Unit after Ischemic Stroke

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 767
Author(s):  
Courtney Davis ◽  
Sean I. Savitz ◽  
Nikunj Satani
Keyword(s):  
Ischemic Stroke ◽  
Extracellular Vesicles ◽  
Neurovascular Unit ◽  
Culture Conditions ◽  
Therapeutic Effects ◽  
Stroke Treatment ◽  
Inflammatory Molecules ◽  
The Brain

Ischemic stroke is a debilitating disease and one of the leading causes of long-term disability. During the early phase after ischemic stroke, the blood-brain barrier (BBB) exhibits increased permeability and disruption, leading to an influx of immune cells and inflammatory molecules that exacerbate the damage to the brain tissue. Mesenchymal stem cells have been investigated as a promising therapy to improve the recovery after ischemic stroke. The therapeutic effects imparted by MSCs are mostly paracrine. Recently, the role of extracellular vesicles released by these MSCs have been studied as possible carriers of information to the brain. This review focuses on the potential of MSC derived EVs to repair the components of the neurovascular unit (NVU) controlling the BBB, in order to promote overall recovery from stroke. Here, we review the techniques for increasing the effectiveness of MSC-based therapeutics, such as improved homing capabilities, bioengineering protein expression, modified culture conditions, and customizing the contents of EVs. Combining multiple techniques targeting NVU repair may provide the basis for improved future stroke treatment paradigms.

scholarly journals Microglia in Neurodegenerative Events—An Initiator or a Significant Other?

2021 ◽  
Vol 22 (11) ◽  
pp. 5818
Author(s):  
Gaylia Jean Harry
Keyword(s):  
Neurovascular Unit ◽  
Cell Types ◽  
In Vitro Assays ◽  
Significant Other ◽  
Neurodegenerative Process ◽  
Target Sites ◽  
Systemic Factors ◽  
Injury And Repair ◽  
The Brain

A change in microglia structure, signaling, or function is commonly associated with neurodegeneration. This is evident in the patient population, animal models, and targeted in vitro assays. While there is a clear association, it is not evident that microglia serve as an initiator of neurodegeneration. Rather, the dynamics imply a close interaction between the various cell types and structures in the brain that orchestrate the injury and repair responses. Communication between microglia and neurons contributes to the physiological phenotype of microglia maintaining cells in a surveillance state and allows the cells to respond to events occurring in their environment. Interactions between microglia and astrocytes is not as well characterized, nor are interactions with other members of the neurovascular unit; however, given the influence of systemic factors on neuroinflammation and disease progression, such interactions likely represent significant contributes to any neurodegenerative process. In addition, they offer multiple target sites/processes by which environmental exposures could contribute to neurodegenerative disease. Thus, microglia at least play a role as a significant other with an equal partnership; however, claiming a role as an initiator of neurodegeneration remains somewhat controversial.

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