scholarly journals Examination of the Blood-to-Brain Transfer of α-Aminoisobutyric Acid and Horseradish Peroxidase: Regional Alterations in Blood—Brain Barrier Function following Acute Hypertension

1986 ◽  
Vol 6 (4) ◽  
pp. 471-480 ◽  
Author(s):  
Mary D. Ellison ◽  
John T. Povlishock ◽  
Ronald L. Hayes
Keyword(s):  
Horseradish Peroxidase ◽  
Blood Brain Barrier ◽  
Brain Regions ◽  
Brain Barrier ◽  
Acute Hypertension ◽  
Aminoisobutyric Acid ◽  
Protein Extravasation ◽  
Blood Brain ◽  
Infusion Of Norepinephrine ◽  
The Brain

Blood–brain barrier (BBB) alterations following acute hypertension were studied in rats, employing as tracers in each animal both horseradish peroxidase (HRP) (MW 40,000) and [14C]α-aminoisobutyric acid ([14C]AIB) (MW 104). Eighteen animals were subjected to acute hypertension induced by the intravenous infusion of norepinephrine bitartrate (NE) (Levophed). Five animals injected with both tracers but not infused with NE served as controls. The brain of each animal was serially sectioned with adjacent sections processed either for macroautoradiography or for light microscopic visualization of HRP reaction product via histochemical reaction with tetramethylbenzidine. Quantitative blood-to-brain transfer constants for AIB were determined in each of 14 brain regions. Qualitative comparisons were also made between the AIB and HRP blood-to-brain extravasation patterns in each group. Acute hypertension increased cerebrovascular permeability to both AIB and HRP in most animals. Topographically, the sites of the most highly elevated AIB transfer corresponded with sites of HRP extravasation. Conversely, all sites of protein passage corresponded spatially to sites of elevated AIB transfer. Brain regions commonly showing increased permeability to both tracers included the cerebral cortices, corpus callosum, and thalamus. Importantly, some brain regions showed elevated AIB transfer constants where protein extravasation was absent. These regions included the caudate–putamen, hippocampus, basal forebrain, and cerebellum. These observations suggest that following acute hypertension, alterations in BBB permeability are not limited to vascular segments allowing protein extravasation.

scholarly journals Imaging the dynamic recruitment of monocytes to the blood–brain barrier and specific brain regions during Toxoplasma gondii infection

2019 ◽  
Vol 116 (49) ◽  
pp. 24796-24807 ◽  
Author(s):  
Christine A. Schneider ◽  
Dario X. Figueroa Velez ◽  
Ricardo Azevedo ◽  
Evelyn M. Hoover ◽  
Cuong J. Tran ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Blood Brain Barrier ◽  
Light Sheet ◽  
Brain Regions ◽  
Brain Barrier ◽  
Cell Segmentation ◽  
Cns Infection ◽  
Light Sheet Microscopy ◽  
Blood Brain ◽  
The Brain

Brain infection by the parasite Toxoplasma gondii in mice is thought to generate vulnerability to predation by mechanisms that remain elusive. Monocytes play a key role in host defense and inflammation and are critical for controlling T. gondii. However, the dynamic and regional relationship between brain-infiltrating monocytes and parasites is unknown. We report the mobilization of inflammatory (CCR2+Ly6Chi) and patrolling (CX3CR1+Ly6Clo) monocytes into the blood and brain during T. gondii infection of C57BL/6J and CCR2RFP/+CX3CR1GFP/+ mice. Longitudinal analysis of mice using 2-photon intravital imaging of the brain through cranial windows revealed that CCR2-RFP monocytes were recruited to the blood–brain barrier (BBB) within 2 wk of T. gondii infection, exhibited distinct rolling and crawling behavior, and accumulated within the vessel lumen before entering the parenchyma. Optical clearing of intact T. gondii-infected brains using iDISCO+ and light-sheet microscopy enabled global 3D detection of monocytes. Clusters of T. gondii and individual monocytes across the brain were identified using an automated cell segmentation pipeline, and monocytes were found to be significantly correlated with sites of T. gondii clusters. Computational alignment of brains to the Allen annotated reference atlas [E. S. Lein et al., Nature 445:168–176 (2007)] indicated a consistent pattern of monocyte infiltration during T. gondii infection to the olfactory tubercle, in contrast to LPS treatment of mice, which resulted in a diffuse distribution of monocytes across multiple brain regions. These data provide insights into the dynamics of monocyte recruitment to the BBB and the highly regionalized localization of monocytes in the brain during T. gondii CNS infection.

scholarly journals Transfer Constants for Blood-Brain Barrier Permeation of the Neuroexcitatory Shellfish Toxin, Domoic Acid

1991 ◽  
Vol 18 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Edward Preston ◽  
Ivo Hynie
Keyword(s):  
Blood Brain Barrier ◽  
Domoic Acid ◽  
Carrier Transport ◽  
Polar Compounds ◽  
Brain Regions ◽  
Brain Barrier ◽  
Adult Rats ◽  
Mean Values ◽  
Blood Brain ◽  
The Brain

ABSTRACT:The cause of the toxic mussel poisoning episode in 1987 was traced to a plankton-produced excitotoxin, domoic acid. Experiments were undertaken to quantitate the degree to which blood-borne domoic acid can permeate the microvasculature to enter the brain. Pentobarbital-anesthetized, adult rats received an i.v. injection of 3H-domoic acid which was permitted to circulate for 3-60 min. Transfer constants (Ki) describing blood-to-brain diffusion of tracer were calculated from analysis of the relationship between brain vs plasma radioactivity with time. Mean values (mL.g-1.s-1 x 106) for permeation into 7 brain regions (n = 10 rats) ranged from 1.60 ± 0.13 (SE) to 1.86 ± 0.33 (cortex, ponsmedulla respectively), and carrier transport or regional selectivity in uptake were not evident. Nephrectomy prior to domoic acid injection resulted in the elevation of circulating plasma tracer level and brain uptake. The Ki values are comparable to those for other polar compounds such as sucrose, and indicate that the blood-brain barrier greatly limits the amount of toxin that enters the brain. Together with absorbed dosage, integrity of the cerebrovascular barrier and normal kidney function are important to the outcome of accidentally ingesting domoic acid.

scholarly journals The S1 protein of SARS-CoV-2 crosses the blood-brain barrier: Kinetics, distribution, mechanisms, and influence of ApoE genotype, sex, and inflammation

2020 ◽  
Author(s):  
Elizabeth M. Rhea ◽  
Aric F. Logsdon ◽  
Kim M. Hansen ◽  
Lindsey Williams ◽  
May Reed ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Blood Brain Barrier ◽  
Apoe Genotype ◽  
Brain Regions ◽  
Brain Barrier ◽  
Productive Infection ◽  
Peripheral Tissues ◽  
Blood Brain ◽  
Commercial Sources ◽  
The Brain

AbstractEvidence strongly suggests that SARS-CoV-2, the cause of COVID-19, can enter the brain. SARS-CoV-2 enters cells via the S1 subunit of its spike protein, and S1 can be used as a proxy for the uptake patterns and mechanisms used by the whole virus; unlike studies based on productive infection, viral proteins can be used to precisely determine pharmacokinetics and biodistribution. Here, we found that radioiodinated S1 (I-S1) readily crossed the murine blood-brain barrier (BBB). I-S1 from two commercial sources crossed the BBB with unidirectional influx constants of 0.287 ± 0.024 μL/g-min and 0.294 ± 0.032 μL/g-min and was also taken up by lung, spleen, kidney, and liver. I-S1 was uniformly taken up by all regions of the brain and inflammation induced by lipopolysaccharide reduced uptake in the hippocampus and olfactory bulb. I-S1 crossed the BBB completely to enter the parenchymal brain space, with smaller amounts retained by brain endothelial cells and the luminal surface. Studies on the mechanisms of transport indicated that I-S1 crosses the BBB by the mechanism of adsorptive transcytosis and that the murine ACE2 receptor is involved in brain and lung uptake, but not that by kidney, liver, or spleen. I-S1 entered brain after intranasal administration at about 1/10th the amount found after intravenous administration and about 0.66% of the intranasal dose entered blood. ApoE isoform or sex did not affect whole brain uptake, but had variable effects on olfactory bulb, liver, spleen, and kidney uptakes. In summary, I-S1 readily crosses the murine BBB, entering all brain regions and the peripheral tissues studied, likely by the mechanism of adsorptive transcytosis.Graphical Abstract

Disruption of the blood-brain barrier in cerebrum and brain stem during acute hypertension

1986 ◽  
Vol 251 (6) ◽  
pp. H1171-H1175 ◽  
Author(s):  
W. G. Mayhan ◽  
F. M. Faraci ◽  
D. D. Heistad
Keyword(s):  
Arterial Pressure ◽  
Brain Stem ◽  
Blood Brain Barrier ◽  
Venous Pressure ◽  
Fluorescent Microscopy ◽  
Systemic Arterial Pressure ◽  
Brain Barrier ◽  
Acute Hypertension ◽  
Blood Brain ◽  
The Brain

The purpose of this study was to examine hemodynamic mechanisms of protection of the blood-brain barrier in the brain stem during acute hypertension. We used a new method to examine the microcirculation of the brain stem. Intravital fluorescent microscopy and fluorescein-labeled dextran were used to evaluate disruption of the blood-brain barrier during acute hypertension in rats. During control conditions, pressure (servo null) in arterioles (60 microns in diameter) was 50 +/- 2% (mean +/- SE) of systemic arterial pressure in the cerebrum and 67 +/- 1% of systemic arterial pressure in the brain stem (P less than 0.05 vs. cerebrum). In the cerebrum, pial venous pressure increased from 7 +/- 1 to 25 +/- 2 mmHg during acute hypertension, and there was marked disruption of the blood-brain barrier in venules (26 +/- 2 leaky sites). In contrast, in the brain stem, pial venous pressure increased from 4 +/- 1 to only 8 +/- 1 mmHg (P less than 0.05 vs. cerebrum), and there was minimal disruption of the blood-brain barrier in venules (1.5 +/- 0.6 leaky sites, P less than 0.05 vs. cerebrum). During acute hypertension, increases in blood flow (microspheres) were less in brain stem than in cerebrum. The findings suggest distribution of vascular resistance differs in the brain stem and cerebrum under control conditions, whereas large arteries account for a greater fraction of resistance in cerebrum; pial venous pressure increases less in brain stem than cerebrum during acute hypertension, so that the blood-brain barrier is protected.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneity of brain blood flow and permeability during acute hypertension

1985 ◽  
Vol 249 (3) ◽  
pp. H629-H637 ◽  
Author(s):  
G. L. Baumbach ◽  
D. D. Heistad
Keyword(s):  
Blood Flow ◽  
Brain Stem ◽  
Blood Brain Barrier ◽  
Regional Differences ◽  
Severe Hypertension ◽  
Brain Barrier ◽  
Acute Hypertension ◽  
Blood Brain ◽  
The Brain ◽  
Increased Blood Flow

The purpose of this study was to examine regional autoregulation of blood flow in the brain during acute hypertension. In anesthetized cats severe hypertension increased blood flow more in cerebrum (159%) and cerebellum (106%) than brain stem (58%). In contrast to the heterogeneous autoregulatory response, hypocapnia produced uniform vasoconstriction in the brain. We also compared vasodilatation during severe hypertension with vasodilatation during hypercapnia. During hypercapnia, blood flow increased as much in brain stem, as in cerebrum and cerebellum. Thus regional differences in autoregulation appear to be specific for autoregulatory stimulus and are not secondary to nonspecific differences in vasoconstrictor or vasodilator capacity. To determine whether the blood-brain barrier is more susceptible to hypertensive disruption in regions with less effective autoregulation, permeability of the barrier was quantitated with 125I-albumin. Severe hypertension produced disruption of the barrier in cerebrum but not in brain stem. Thus there are parallel differences in effectiveness of autoregulation and susceptibility to disruption of the blood-brain barrier in different regions of the brain.

scholarly journals Non-Human Primate Blood–Brain Barrier and In Vitro Brain Endothelium: From Transcriptome to the Establishment of a New Model

Pharmaceutics ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 967
Author(s):  
Catarina Chaves ◽  
Tuan-Minh Do ◽  
Céline Cegarra ◽  
Valérie Roudières ◽  
Sandrine Tolou ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Brain Structures ◽  
Brain Regions ◽  
Brain Barrier ◽  
Brain Endothelium ◽  
Slc Transporters ◽  
Blood Brain ◽  
The Brain ◽  
Human Primate

The non-human primate (NHP)-brain endothelium constitutes an essential alternative to human in the prediction of molecule trafficking across the blood–brain barrier (BBB). This study presents a comparison between the NHP transcriptome of freshly isolated brain microcapillaries and in vitro-selected brain endothelial cells (BECs), focusing on important BBB features, namely tight junctions, receptors mediating transcytosis (RMT), ABC and SLC transporters, given its relevance as an alternative model for the molecule trafficking prediction across the BBB and identification of new brain-specific transport mechanisms. In vitro BECs conserved most of the BBB key elements for barrier integrity and control of molecular trafficking. The function of RMT via the transferrin receptor (TFRC) was characterized in this NHP-BBB model, where both human transferrin and anti-hTFRC antibody showed increased apical-to-basolateral passage in comparison to control molecules. In parallel, eventual BBB-related regional differences were Investig.igated in seven-day in vitro-selected BECs from five brain structures: brainstem, cerebellum, cortex, hippocampus, and striatum. Our analysis retrieved few differences in the brain endothelium across brain regions, suggesting a rather homogeneous BBB function across the brain parenchyma. The presently established NHP-derived BBB model closely mimics the physiological BBB, thus representing a ready-to-use tool for assessment of the penetration of biotherapeutics into the human CNS.

Ontogeny of blood-brain barrier function in ovine fetuses, lambs, and adults

1996 ◽  
Vol 271 (6) ◽  
pp. R1594-R1601 ◽  
Author(s):  
B. S. Stonestreet ◽  
C. S. Patlak ◽  
K. D. Pettigrew ◽  
C. B. Reilly ◽  
H. F. Cserr
Keyword(s):  
Blood Brain Barrier ◽  
Barrier Function ◽  
Brain Regions ◽  
Brain Barrier ◽  
Small Molecular Weight ◽  
Regional Heterogeneity ◽  
Regional Brain ◽  
Blood Brain ◽  
Brain Barrier Permeability ◽  
The Brain

The ontogeny of regional blood-brain barrier function was quantified with the rate constant for influx (Ki) across the blood-brain barrier with the small molecular weight synthetic, inert hydrophilic amino acid alpha-aminoisobutyric acid (AIB) in chronically instrumented early (87 days of gestation, 60% of gestation) and late (137 days of gestation, 90% of gestation) gestation fetal, newborn (3 days of age), older (24 days of age), and adult (3 years of age) sheep. The Ki was significantly (P < 0.05) lower in the brain regions of the adult sheep and in most brain regions of newborn and older lambs compared with fetuses at 60 and 90% of gestation. The Ki exhibited regional brain heterogeneity (P < 0.05) in the five groups. The patterns of regional heterogeneity were accentuated (P < 0.05) in the younger groups. We conclude that ontogenic decreases in blood-brain barrier permeability are observed in ovine fetuses from 60% of gestation to maturity in the adult.

Further evidence that the blood/brain barrier impedes paraquat entry into the brain

1995 ◽  
Vol 14 (7) ◽  
pp. 587-594 ◽  
Author(s):  
JL Naylor ◽  
PS Widdowson ◽  
MG Simpson ◽  
M. Farnworth ◽  
MK Ellis ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Area Postrema ◽  
Neuronal Cell ◽  
Brain Regions ◽  
Systemic Administration ◽  
Brain Barrier ◽  
Adult Rats ◽  
Male Adult ◽  
Blood Brain ◽  
The Brain

The distribution of the non-selective herbicide paraquat was examined in the brain following subcutaneous admin istration of 20 mg kg -1 paraquat ion containing [14C]paraquat to male adult rats in order to determine whether paraquat crosses the blood/brain barrier. Following administration, [14C]paraquat reached a maxi mal concentration in the brain (0.05% of administered dose) within the first hour and then rapidly disappeared from the brain. However, 24 h after administration of the herbicide, about 13% of the maximal recorded concentra tion of paraquat remained in the brain (1.6 nmol g-1 wet weight) and could not be removed by intracardiac perfu sion. Using measurements of [14C]paraquat in dissected brain regions and using quantitative autoradiography we demonstrated an asymmetrical distribution in and around the brain at 30 min (maximal concentration) and 24 h after administration. Most of the paraquat was associated with five structures, two of which, the pineal gland and linings of the cerebral ventricles lie outside the blood/brain barrier whilst the remaining three brain areas, the anterior portion of the olfactory bulb, hypothalamus and area postrema do not have a blood/brain barrier. Overall, the distribution of [14C]paraquat in the brain 24 h after systemic administration was highly correlated to the blood volume. These data indicate that any remaining paraquat in the brain 24 h after systemic administration is associated with elements of the cerebro-circulatory sys tem, such as the endothelial cells that make up the capil lary network and that there is a limited entry of paraquat into brain regions without a blood/brain barrier. No [14C]paraquat was detected in regions where there has been demonstrated pathology in brains from humans with Parkinson's disease. Finally, we could find no evidence for paraquat-induced neuronal cell necrosis 24 or 48 h after systemic administration. Overall it may be concluded that systemically administered paraquat does not pose a direct major neurotoxicological risk in the majority of brain regions which have a functional blood/brain barrier since paraquat can be excluded from the brain by this barrier.

Saturable binding of circulating peptide YY in the dorsal vagal complex of rats

1994 ◽  
Vol 266 (3) ◽  
pp. G511-G516 ◽  
Author(s):  
E. J. Hernandez ◽  
D. C. Whitcomb ◽  
S. R. Vigna ◽  
I. L. Taylor
Keyword(s):  
Blood Brain Barrier ◽  
Plasma Volume ◽  
Peptide Yy ◽  
Brain Regions ◽  
Brain Barrier ◽  
Dorsal Vagal Complex ◽  
Physiological Conditions ◽  
Blood Brain ◽  
Saturable Binding ◽  
The Brain

The rationale for this study was to test the hypothesis that peripherally released peptide YY (PYY) acts in the vagal nuclear complex of the medulla oblongata to modulate vagal tone centrally. The objective was to determine whether circulating PYY gains access to and binds to the receptors identified in the dorsal vagal complex (DVC) under physiological conditions. Specific brain regions were microdissected after intravenous 125I-labeled PYY and 131I-labeled bovine serum albumin infusions to determine saturable accumulation of PYY in the brain and to determine if there were changes in plasma volume with large PYY infusions. Significant (P < 0.05) saturable binding was observed in the region of the brain stem containing the DVC and the pituitary. There were no significant changes in plasma volume in any region after the infusion of the excess nonradioactive PYY. We conclude that under physiological conditions circulating PYY binds to sites in the pituitary and portions of the DVC that have PYY receptors and an incomplete blood-brain barrier but does not bind to other areas that have an intact blood-brain barrier. Therefore this peripheral hormone may act centrally to modulate the digestive system and is a member of a novel class of gut hormones that function as central neuromodulators.

scholarly journals Region-specific permeability of the blood–brain barrier upon pericyte loss

2017 ◽  
Vol 37 (12) ◽  
pp. 3683-3694 ◽  
Author(s):  
Roberto Villaseñor ◽  
Basil Kuennecke ◽  
Laurence Ozmen ◽  
Michelle Ammann ◽  
Christof Kugler ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Brain Regions ◽  
Brain Parenchyma ◽  
Brain Barrier ◽  
Regional Heterogeneity ◽  
Blood Brain ◽  
Specific Permeability ◽  
Bbb Permeability ◽  
Pericyte Loss ◽  
The Brain

The blood–brain barrier (BBB) regulates differing needs of the various brain regions by controlling transport of blood-borne components from the neurovascular circulation into the brain parenchyma. The mechanisms underlying region-specific transport across the BBB are not completely understood. Previous work showed that pericytes are key regulators of BBB function. Here we investigated whether pericytes influence BBB permeability in a region-specific manner by analysing the regional permeability of the BBB in the pdgf-b ret/ret mouse model of pericyte depletion. We show that BBB permeability is heterogeneous in pdgf-b ret/ret mice, being significantly higher in the cortex, striatum and hippocampus compared to the interbrain and midbrain. However, we show that this regional heterogeneity in BBB permeability is not explained by local differences in pericyte coverage. Region-specific differences in permeability were not associated with disruption of tight junctions but may result from changes in transcytosis across brain endothelial cells. Our data show that certain brain regions are able to maintain low BBB permeability despite substantial pericyte loss and suggest that additional, locally-acting mechanisms may contribute to control of transport.

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