scholarly journals The Precapillary Segment of the Blood-Brain Barrier and Its Relation to Perivascular Drainage in Alzheimer's Disease and Small Vessel Disease.

2009 ◽  
Vol 9 ◽  
pp. 557-563 ◽  
Author(s):  
Dietmar R. Thal
Keyword(s):  
Brain Tissue ◽  
Blood Brain Barrier ◽  
Vessel Wall ◽  
Small Vessel Disease ◽  
Extracellular Fluid ◽  
Perivascular Space ◽  
Brain Barrier ◽  
Vessel Disease ◽  
The Brain ◽  
Perivascular Drainage

The blood-brain barrier (BBB) is the border between the brain tissue and the blood and consists of a pre- and post-capillary and a capillary segment. At capillaries protein transport is possible via receptor-mediated endocytosis through endothelial cells. At the arteries and veins the BBB is thicker and there is, under physiological conditions, no direct transport from the brain tissue to the blood or vice versa. Here, extracellular fluid is drained into the perivascular space, which is a fluid-filled space between the border of the brain tissue, the glia limitans, and that of the vessel wall, the adventitia as well as along basement membranes within the vessel wall. In the event of degenerative changes in the arterial vessel wall, known as small vessel disease (SVD), leakage of plasma proteins into the vessel wall and into the perivascular space occurs. Thus, the pre-capillary segment of the BBB is altered and drainage of extracellular fluid from the brain tissue competes with the leaking plasma for perivascular drainage. Since the amyloid ß-protein (Aß) is subject of this perivascular drainage and accumulates in the brains of Alzheimer's disease (AD) patients, an alteration of this drainage system in the course of SVD may support the accumulation of Aß within the brain and, in so doing, the development of AD.

scholarly journals Structural, Molecular, and Functional Alterations of the Blood-Brain Barrier during Epileptogenesis and Epilepsy: A Cause, Consequence, or Both?

2020 ◽  
Vol 21 (2) ◽  
pp. 591 ◽  
Author(s):  
Wolfgang Löscher ◽  
Alon Friedman
Keyword(s):  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Defense Mechanism ◽  
Extracellular Fluid ◽  
Cell Types ◽  
Therapeutic Interventions ◽  
Brain Barrier ◽  
Transport Systems ◽  
Blood Brain ◽  
The Brain

The blood-brain barrier (BBB) is a dynamic, highly selective barrier primarily formed by endothelial cells connected by tight junctions that separate the circulating blood from the brain extracellular fluid. The endothelial cells lining the brain microvessels are under the inductive influence of neighboring cell types, including astrocytes and pericytes. In addition to the anatomical characteristics of the BBB, various specific transport systems, enzymes and receptors regulate molecular and cellular traffic across the BBB. While the intact BBB prevents many macromolecules and immune cells from entering the brain, following epileptogenic brain insults the BBB changes its properties. Among BBB alterations, albumin extravasation and diapedesis of leucocytes from blood into brain parenchyma occur, inducing or contributing to epileptogenesis. Furthermore, seizures themselves may modulate BBB functions, permitting albumin extravasation, leading to activation of astrocytes and the innate immune system, and eventually modifications of neuronal networks. BBB alterations following seizures are not necessarily associated with enhanced drug penetration into the brain. Increased expression of multidrug efflux transporters such as P-glycoprotein likely act as a ‘second line defense’ mechanism to protect the brain from toxins. A better understanding of the complex alterations in BBB structure and function following seizures and in epilepsy may lead to novel therapeutic interventions allowing the prevention and treatment of epilepsy as well as other detrimental neuro-psychiatric sequelae of brain injury.

Entry of CART into brain is rapid but not inhibited by excess CART or leptin

1999 ◽  
Vol 277 (5) ◽  
pp. E901-E904 ◽  
Author(s):  
Abba J. Kastin ◽  
Victoria Akerstrom
Keyword(s):  
Endothelial Cells ◽  
Regression Analysis ◽  
Brain Tissue ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Multiple Time ◽  
Rapid Rate ◽  
Efflux System ◽  
Anorectic Agent ◽  
The Brain

Cocaine- and amphetamine-regulated transcript (CART) is a new anorectic peptide found in the brain and periphery. It is closely associated with leptin, an anorectic agent saturably transported across the blood-brain barrier (BBB). Using multiple time-regression analysis, we found that CART has a rapid rate of entry into brain from blood. However, there was no self-inhibition with CART, even when perfused in blood-free buffer or in fasted mice, showing a lack of saturation. HPLC showed that at least 58% of the injected CART reached brain tissue in intact form, and capillary depletion with and without washout showed that the CART was not bound to endothelial cells or adherent to vascular components. There was no evidence for an efflux system out of the brain for CART. Thus CART can cross the BBB from blood to brain, but its rapid rate of entry is not inhibited by excess CART or leptin.

Solving the challenge of the blood–brain barrier to treat infections caused by Trypanosoma evansi: evaluation of nerolidol-loaded nanospheres in mice

Parasitology ◽  
2017 ◽  
Vol 144 (11) ◽  
pp. 1543-1550 ◽  
Author(s):  
MATHEUS D. BALDISSERA ◽  
CARINE F. SOUZA ◽  
ALINE A. BOLIGON ◽  
THIRSSA H. GRANDO ◽  
MARIÂNGELA F. DE SÁ ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Blood Brain Barrier ◽  
High Performance ◽  
Drug Efficacy ◽  
Trypanosoma Evansi ◽  
Brain Barrier ◽  
Active Principle ◽  
Diminazene Aceturate ◽  
Blood Brain ◽  
The Brain

SUMMARYDespite significant advances in therapies against Trypanosoma evansi, its effective elimination from the central nervous system (CNS) remains a difficult task. The incapacity of trypanocidal drugs to cross the blood–brain barrier (BBB) after systemic administrations makes the brain the main refuge area for T. evansi. Nanotechnology is showing great potential to improve drug efficacy, such as nerolidol-loaded nanospheres (N-NS). Thus, the aim of this study was to investigate whether the treatment with N-NS was able to cross the BBB and to eliminate T. evansi from the CNS. High-performance liquid chromatography revealed that N-NS can cross the BBB of T. evansi-infected mice, while free nerolidol (F-N) neither the trypanocidal drug diminazene aceturate (D.A.) were not detected in the brain tissue. Polymerase chain reaction revealed that 100% of the animals treated with N-NS were negatives for T. evansi in the brain tissue, while all infected animals treated with F-N or D.A. were positives. Thus, we concluded that nanotechnology improves the therapeutic efficacy of nerolidol, and enables the transport of its active principle through the BBB. In summary, N-NS treatment can eliminate the parasite from the CNS, and possesses potential to treat infected animals.

scholarly journals CT Imaging and Spontaneous Behavior Analysis After Osmotic Blood-Brain Barrier Opening in Wistar Rat

2014 ◽  
pp. S529-S534 ◽  
Author(s):  
P. KOZLER ◽  
V. RILJAK ◽  
K. JANDOVÁ ◽  
J. POKORNÝ
Keyword(s):  
Locomotor Activity ◽  
Brain Edema ◽  
Brain Tissue ◽  
Blood Brain Barrier ◽  
Spontaneous Locomotor Activity ◽  
Brain Barrier ◽  
Male Rats ◽  
Blood Brain ◽  
Significant Difference ◽  
The Brain

In our previous experiments we demonstrated that osmotic opening of the blood brain barrier (BBB) in rats by administration of mannitol into the internal carotid artery leads to cerebral edema. The aim of this study was to confirm objectively the development of brain edema and determine whether it affects spontaneous locomotor activity in rats (SLA). Brain edema was verified by computer tomography (CT) examination of the brain and SLA was observed during open field test. Twenty four adult male rats were divided into four groups of six: (1) control animals (C), (2) controls with anesthesia (CA), (3) controls with sham surgery (CS), (4) experimental – osmotic opening of the BBB (MA). Osmotic BBB disruption manifested by reducing the density of brain tissue (hypodensity), suggesting a higher water content in the brain tissue. SLA was compared between C, CA, CS and MA groups and between MA and CA groups. Significant difference was found only between the control group and MA group. In the first 30 min of the examination, rats after the mannitol administration revealed a marked limitation of spontaneous locomotor activity. Experimental results demonstrated reduction of spontaneous locomotor activity in rats with induced brain edema.

scholarly journals Evaluating blood-brain barrier permeability in a rat model of type 2 diabetes

2020 ◽  
Author(s):  
Craig Ferris ◽  
Ju Qiao ◽  
Christopher M Lawson ◽  
Kilian FG Rentrup ◽  
Praveen Kulkarni
Keyword(s):  
Type 2 Diabetes ◽  
Blood Brain Barrier ◽  
Small Vessel Disease ◽  
Brain Barrier ◽  
Barrier Permeability ◽  
Blood Brain Barrier Permeability ◽  
Blood Brain ◽  
Brain Barrier Permeability ◽  
The Brain

Abstract Background This is an exploratory study using a novel imaging modality, quantitative ultrashort time-to-echo, contrast enhanced (QUTE-CE) magnetic resonance imaging to evaluate the permeability of the blood brain barrier in a rat model of type 2 diabetes with the presumption that small vessel disease is a contributing factor to neuropathology in diabetes. Methods The BBZDR/Wor rat, a model of type 2 diabetes, and age-matched controls were studied for changes in blood brain barrier permeability. QUTE-CE, a quantitative vascular biomarker, generated angiographic images with over 500,000 voxels that were registered to a 3D MRI rat brain atlas providing site-specific information on blood-brain barrier permeability in 173 different brain areas. Results In this model of diabetes, without the support of insulin treatment, there was global capillary pathology with over 84% of the brain showing a significant increase in blood brain barrier permeability over wild-type controls. Areas of the cerebellum and midbrain dopaminergic system were not significantly affected.Conclusion Small vessel disease as assessed by permeability in the blood brain barrier in type 2 diabetes is pervasive and includes much of the brain. The increase in blood-brain barrier permeability is a likely contributing factor to diabetic encephalopathy and dementia.

scholarly journals Blood-brain barrier impairment and hypoperfusion are linked in cerebral small vessel disease

Neurology ◽  
2019 ◽  
Vol 92 (15) ◽  
pp. e1669-e1677 ◽  
Author(s):  
Sau May Wong ◽  
Jacobus F.A. Jansen ◽  
C. Eleana Zhang ◽  
Erik I. Hoff ◽  
Julie Staals ◽  
...  
Keyword(s):  
White Matter ◽  
Blood Brain Barrier ◽  
Small Vessel Disease ◽  
Cerebral Small Vessel Disease ◽  
Brain Barrier ◽  
Small Vessel ◽  
Dynamic Susceptibility ◽  
Vessel Disease ◽  
Blood Brain ◽  
Bbb Permeability

ObjectiveTo investigate the link between blood-brain-barrier (BBB) permeability and cerebral blood flow (CBF) and the relation with white matter hyperintensities (WMH) in cerebral small vessel disease (cSVD).MethodsTwenty-seven patients with cSVD received dynamic susceptibility contrast and dynamic contrast-enhanced MRI to determine CBF and BBB permeability (expressed as leakage rate and volume), respectively. Structural MRI were segmented into normal-appearing white matter (NAWM) and WMH, for which a perilesional zone was defined. In these regions, we investigated the BBB permeability, CBF, and their relation using Pearson correlation r.ResultsWe found a decrease in CBF of 2.2 mL/min/100 g (p < 0.01) and an increase in leakage volume of 0.7% (p < 0.01) per mm closer to the WMH in the perilesional zones. Lower CBF values correlated with higher leakage measures in the NAWM and WMH (−0.53 < r < −0.40, p < 0.05). This relation was also observed in the perilesional zones, which became stronger in the proximity of WMH (p = 0.03).ConclusionBBB impairment and hypoperfusion appear in the WMH and NAWM, which increase in the proximity of the WMH, and are linked. Both BBB and CBF are regulated in the neurovascular unit (NVU) and the observed link might be due to the physiologic regulation mechanism of the NVU. This link may suggest an early overall deterioration of this unit.

scholarly journals Empirical and Theoretical Characterization of the Diffusion Process of Different Gadolinium-Based Nanoparticles within the Brain Tissue after Ultrasound-Induced Permeabilization of the Blood-Brain Barrier

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Allegra Conti ◽  
Rémi Magnin ◽  
Matthieu Gerstenmayer ◽  
Nicolas Tsapis ◽  
Erik Dumont ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Brain Tissue ◽  
Blood Brain Barrier ◽  
Diffusion Coefficients ◽  
Brain Barrier ◽  
Apparent Diffusion Coefficients ◽  
Blood Brain ◽  
The Brain ◽  
And Diffusion

Low-intensity focused ultrasound (FUS), combined with microbubbles, is able to locally, and noninvasively, open the blood-brain barrier (BBB), allowing nanoparticles to enter the brain. We present here a study on the diffusion process of gadolinium-based MRI contrast agents within the brain extracellular space after ultrasound-induced BBB permeabilization. Three compounds were tested (MultiHance, Gadovist, and Dotarem). We characterized their diffusion through in vivo experimental tests supported by theoretical models. Specifically, by estimation of the free diffusion coefficients from in vitro studies and of apparent diffusion coefficients from in vivo experiments, we have assessed tortuosity in the right striatum of 9 Sprague Dawley rats through a model correctly describing both vascular permeability as a function of time and diffusion processes occurring in the brain tissue. This model takes into account acoustic pressure, particle size, blood pharmacokinetics, and diffusion rates. Our model is able to fully predict the result of a FUS-induced BBB opening experiment at long space and time scales. Recovered values of tortuosity are in agreement with the literature and demonstrate that our improved model allows us to assess that the chosen permeabilization protocol preserves the integrity of the brain tissue.

Potential Regulation Mechanisms of P-gp in the Blood-Brain Barrier in Hypoxia

2019 ◽  
Vol 25 (10) ◽  
pp. 1041-1051 ◽  
Author(s):  
Yidan Ding ◽  
Rong Wang ◽  
Jianchun Zhang ◽  
Anpeng Zhao ◽  
Hui Lu ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Brain Tissue ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Signal Pathways ◽  
Blood Brain ◽  
Sphingosine 1 Phosphate ◽  
Capillary Endothelial Cells ◽  
The Brain ◽  
Expression And Activity

The blood-brain barrier (BBB) is a barrier of the central nervous system (CNS), which can restrict the free exchange of substances, such as toxins and drugs, between cerebral interstitial fluid and blood, keeping the relative physiological stabilization. The brain capillary endothelial cells, one of the structures of the BBB, have a variety of ATP-binding cassette transporters (ABC transporters), among which the most widely investigated is Pglycoprotein (P-gp) that can efflux numerous substances out of the brain. The expression and activity of P-gp are regulated by various signal pathways, including tumor necrosis factor-&#945; (TNF-&#945;)/protein kinase C-&#946; (PKC- &#946;)/sphingosine-1-phosphate receptor 1 (S1P), vascular endothelial growth factor (VEGF)/Src kinase, etc. However, it remains unclear how hypoxic signaling pathways regulate the expression and activity of P-gp in brain microvascular endothelial cells. According to previous research, hypoxia affects the expression and activity of the transporter. If the transporter is up-regulated, some drugs enter the brain&#039;s endothelial cells and are pumped back into the blood by transporters such as P-gp before they enter the brain tissue, consequently influencing the drug delivery in CNS; if the transporter is down-regulated, the centrally toxic drug would enter the brain tissue and cause serious adverse reactions. Therefore, studying the mechanism of hypoxia-regulating P-gp can provide an important reference for the treatment of CNS diseases with a hypoxia/reoxygenation (H/R) component. This article summarized the mechanism of regulation of P-gp in BBB in normoxia and explored that of hypoxia.

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