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.

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-α (TNF-α)/protein kinase C-β (PKC- β)/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'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.

scholarly journals P-Glycoprotein-Mediated Transport of Itraconazole across the Blood-Brain Barrier

1998 ◽  
Vol 42 (7) ◽  
pp. 1738-1744 ◽  
Author(s):  
Tetsuo Miyama ◽  
Hitomi Takanaga ◽  
Hirotami Matsuo ◽  
Katsuhiro Yamano ◽  
Koujirou Yamamoto ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Brain Tissue ◽  
Blood Brain Barrier ◽  
Half Life ◽  
Liver Tissue ◽  
Brain Barrier ◽  
Brain Capillary ◽  
P Glycoprotein ◽  
Capillary Endothelial Cells ◽  
The Brain

ABSTRACT The mechanism for the accumulation of itraconazole (ITZ) in its elimination from the brain was studied in rats and mice. The concentration of ITZ in liver tissue declined in parallel with the plasma ITZ concentration until 24 h after intravenous injection of the drug (half-life, 5 h); however, the ITZ in brain tissue rapidly disappeared (half-life, 0.4 h). The time profiles of the brain/plasma ITZ concentration ratio (Kp value) showed a marked overshooting, and the Kp value increased with increasing dose; these phenomena were not observed in the liver tissue. This finding indicates the occurrence of a nonlinear efflux of ITZ from the brain to the blood. Moreover, based on a pharmacokinetic model which hypothesized processes for both nonlinear and linear effluxes of ITZ from the brain to the blood, we found that the efflux rate constant in the saturable process was approximately sevenfold larger than that in the nonsaturable process. TheKp value for the brain tissue was significantly increased in the presence of ketoconazole or verapamil. The brainKp value for mdr1a knockout mice was also significantly increased compared with that of control mice. Moreover, the uptake of vincristine or vinblastine, both of which are substrates of the P glycoprotein (P-gp), into mouse brain capillary endothelial cells was also significantly increased by ITZ or verapamil. In conclusion, P-gp in the brain capillary endothelial cells participates in a process of active efflux of ITZ from the brain to the blood at the blood-brain barrier, and ITZ can be an inhibitor of various substrates of P-gp.

Anthropogenic Iron Oxide Nanoparticles Induce Damage to Brain Microvascular Endothelial Cells Forming the Blood-Brain Barrier

2021 ◽  
Author(s):  
Lorena Gárate-Vélez ◽  
Claudia Escudero-Lourdes ◽  
Daniela Salado-Leza ◽  
Armando González-Sánchez ◽  
Ildemar Alvarado-Morales ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Blood Brain ◽  
Fe3o4 Nps ◽  
Microvascular Endothelial ◽  
The Brain

Background: Iron nanoparticles, mainly in magnetite phase (Fe3O4 NPs), are released to the environment in areas with high traffic density and braking frequency. Fe3O4 NPs were found in postmortem human brains and are assumed to get directly into the brain through the olfactory nerve. However, these pollution-derived NPs may also translocate from the lungs to the bloodstream and then, through the blood-brain barrier (BBB), into the brain inducing oxidative and inflammatory responses that contribute to neurodegeneration. Objective: To describe the interaction and toxicity of pollution-derived Fe3O4 NPs on primary rat brain microvascular endothelial cells (rBMECs), main constituents of in vitro BBB models. Methods: Synthetic bare Fe3O4 NPs that mimic the environmental ones (miFe3O4) were synthesized by co-precipitation and characterized using complementary techniques. The rBMECs were cultured in Transwell® plates. The NPs-cell interaction was evaluated through transmission electron microscopy and standard colorimetric in vitro assays. Results: The miFe3O4 NPs, with a mean diameter of 8.45 ± 0.14 nm, presented both magnetite and maghemite phases, and showed super-paramagnetic properties. Results suggest that miFe3O4 NPs are internalized by rBMECs through endocytosis and that they are able to cross the cells monolayer. The lowest miFe3O4 NPs concentration tested induced mid cytotoxicity in terms of 1) membrane integrity (LDH release) and 2) metabolic activity (MTS transformation). Conclusion: Pollution-derived Fe3O4 NPs may interact and cross the microvascular endothelial cells forming the BBB and cause biological damage.

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.

scholarly journals Impact of the Renin–Angiotensin System on the Endothelium in Vascular Dementia: Unresolved Issues and Future Perspectives

2020 ◽  
Vol 21 (12) ◽  
pp. 4268 ◽  
Author(s):  
Fatima Y. Noureddine ◽  
Raffaele Altara ◽  
Fan Fan ◽  
Andriy Yabluchanskiy ◽  
George W. Booz ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Dementia ◽  
Blood Brain Barrier ◽  
Renin Angiotensin System ◽  
Brain Barrier ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Blood Brain ◽  
Body Tissues ◽  
The Brain

The effects of the renin–angiotensin system (RAS) surpass the renal and cardiovascular systems to encompass other body tissues and organs, including the brain. Angiotensin II (Ang II), the most potent mediator of RAS in the brain, contributes to vascular dementia via different mechanisms, including neuronal homeostasis disruption, vascular remodeling, and endothelial dysfunction caused by increased inflammation and oxidative stress. Other RAS components of emerging significance at the level of the blood–brain barrier include angiotensin-converting enzyme 2 (ACE2), Ang(1–7), and the AT2, Mas, and AT4 receptors. The various angiotensin hormones perform complex actions on brain endothelial cells and pericytes through specific receptors that have either detrimental or beneficial actions. Increasing evidence indicates that the ACE2/Ang(1–7)/Mas axis constitutes a protective arm of RAS on the blood–brain barrier. This review provides an update of studies assessing the different effects of angiotensins on cerebral endothelial cells. The involved signaling pathways are presented and help highlight the potential pharmacological targets for the management of cognitive and behavioral dysfunctions associated with vascular dementia.

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 The Dual Role of Microglia in Blood-Brain Barrier Dysfunction after Stroke

2020 ◽  
Vol 18 (12) ◽  
pp. 1237-1249 ◽  
Author(s):  
Ruiqing Kang ◽  
Marcin Gamdzyk ◽  
Cameron Lenahan ◽  
Jiping Tang ◽  
Sheng Tan ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Vital Role ◽  
Dual Role ◽  
Brain Barrier ◽  
Barrier Dysfunction ◽  
Blood Brain ◽  
M2 Microglia ◽  
The Brain

It is well-known that stroke is one of the leading causes of death and disability all over the world. After a stroke, the blood-brain barrier subsequently breaks down. The BBB consists of endothelial cells surrounded by astrocytes. Microglia, considered the long-living resident immune cells of the brain, play a vital role in BBB function. M1 microglia worsen BBB disruption, while M2 microglia assist in repairing BBB damage. Microglia can also directly interact with endothelial cells and affect BBB permeability. In this review, we are going to discuss the mechanisms responsible for the dual role of microglia in BBB dysfunction after stroke.

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 Human pluripotent stem cell-derived brain pericyte-like cells induce blood-brain barrier properties

2018 ◽  
Author(s):  
Matthew J. Stebbins ◽  
Benjamin D. Gastfriend ◽  
Scott G. Canfield ◽  
Ming-Song Lee ◽  
Drew Richards ◽  
...  
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Pluripotent Stem Cells ◽  
Neurovascular Unit ◽  
Human Pluripotent Stem Cells ◽  
Brain Barrier ◽  
Blood Brain ◽  
Brain Pericytes ◽  
The Brain

ABSTRACTBrain pericytes play an important role in the formation and maintenance of the neurovascular unit (NVU), and their dysfunction has been implicated in central nervous system (CNS) disorders. While human pluripotent stem cells (hPSCs) have been used to model other components of the NVU including brain microvascular endothelial cells (BMECs), astrocytes, and neurons, cells having brain pericyte-like phenotypes have not been described. In this study, we generated neural crest stem cells (NCSCs), the embryonic precursor to forebrain pericytes, from human pluripotent stem cells (hPSCs) and subsequently differentiated NCSCs to brain pericyte-like cells. The brain pericyte-like cells expressed marker profiles that closely resembled primary human brain pericytes, and they self-assembled with endothelial cells to support vascular tube formation. Importantly, the brain pericyte-like cells induced blood-brain barrier (BBB) properties in BMECs, including barrier enhancement and reduction of transcytosis. Finally, brain pericyte-like cells were incorporated with iPSC-derived BMECs, astrocytes, and neurons to form an isogenic human NVU model that should prove useful for the study of the BBB in CNS health, disease, and therapy.

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