The betaine-GABA transporter (BGT1, slc6a12) is predominantly expressed in the liver and at lower levels in the kidneys and at the brain surface

2012 ◽  
Vol 302 (3) ◽  
pp. F316-F328 ◽  
Author(s):  
Y. Zhou ◽  
S. Holmseth ◽  
R. Hua ◽  
A. C. Lehre ◽  
A. M. Olofsson ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Renal Medulla ◽  
Brain Parenchyma ◽  
Ependymal Cells ◽  
Main Role ◽  
Mrna Levels ◽  
Physiological Importance ◽  
Brain Surface ◽  
Negative Controls ◽  
The Brain

The Na+- and Cl−-dependent GABA-betaine transporter (BGT1) has received attention mostly as a protector against osmolarity changes in the kidney and as a potential controller of the neurotransmitter GABA in the brain. Nevertheless, the cellular distribution of BGT1, and its physiological importance, is not fully understood. Here we have quantified mRNA levels using TaqMan real-time PCR, produced a number of BGT1 antibodies, and used these to study BGT1 distribution in mice. BGT1 (protein and mRNA) is predominantly expressed in the liver (sinusoidal hepatocyte plasma membranes) and not in the endothelium. BGT1 is also present in the renal medulla, where it localizes to the basolateral membranes of collecting ducts (particularly at the papilla tip) and the thick ascending limbs of Henle. There is some BGT1 in the leptomeninges, but brain parenchyma, brain blood vessels, ependymal cells, the renal cortex, and the intestine are virtually BGT1 deficient in 1- to 3-mo-old mice. Labeling specificity was assured by processing tissue from BGT1-deficient littermates in parallel as negative controls. Addition of 2.5% sodium chloride to the drinking water for 48 h induced a two- to threefold upregulation of BGT1, tonicity-responsive enhancer binding protein, and sodium- myo-inositol cotransporter 1 (slc5a3) in the renal medulla, but not in the brain and barely in the liver. BGT1-deficient and wild-type mice appeared to tolerate the salt treatment equally well, possibly because betaine is one of several osmolytes. In conclusion, this study suggests that BGT1 plays its main role in the liver, thereby complementing other betaine-transporting carrier proteins (e.g., slc6a20) that are predominantly expressed in the small intestine or kidney rather than the liver.

scholarly journals New optical method for analyzing cortical blood flow heterogeneity in small animals: validation of the method

2000 ◽  
Vol 279 (3) ◽  
pp. H1291-H1298 ◽  
Author(s):  
Istvan Schiszler ◽  
Minoru Tomita ◽  
Yasuo Fukuuchi ◽  
Norio Tanahashi ◽  
Koji Inoue
Keyword(s):  
Blood Flow ◽  
Mean Transit Time ◽  
Region Of Interest ◽  
Brain Parenchyma ◽  
Sprague Dawley ◽  
Doppler Flowmetry ◽  
Cranial Window ◽  
Brain Surface ◽  
Fine Glass ◽  
The Brain

In pentobarbital-anesthetized male Sprague-Dawley rats, a small cranial window was trephined, and the cortex was transilluminated with a fine glass fiber inserted into the brain parenchyma. The light intensity at the surface area of 2 × 2 mm was recorded during intracarotid injection of 25 μl of carbon black (CB) solution. The region of interest (ROI) was divided into a 50 × 50 matrix, and the mean transit time of CB transport was calculated in each matrix element. We found rapid transits of CB along the microvasculature, with considerable heterogeneity in the avascular area, and heterogeneous efficiency in autoregulatory capacity in the ROI during hypotension. The method was validated by comparison with laser-Doppler flowmetry. The average mean difference was 0.03 ± 0.05%. Five percent CO2 inhalation increased the flow by 85%, but heterogeneously. We concluded that the technique is exclusively sensitive to indicator transits in a very small area on the brain surface with potential usefulness in detecting regional heterogeneity in blood flow.

scholarly journals Application of fluorescent dextrans to the brain surface under constant pressure reveals AQP4-independent solute uptake

2021 ◽  
Vol 153 (8) ◽  
Author(s):  
Alex J. Smith ◽  
Gokhan Akdemir ◽  
Meetu Wadhwa ◽  
Dan Song ◽  
Alan S. Verkman
Keyword(s):  
Constant Pressure ◽  
Water Channel ◽  
Solute Concentration ◽  
External Pressure ◽  
Brain Parenchyma ◽  
Interstitial Space ◽  
Brain Surface ◽  
Solute Uptake ◽  
The Brain

Extracellular solutes in the central nervous system are exchanged between the interstitial fluid, the perivascular compartment, and the cerebrospinal fluid (CSF). The “glymphatic” mechanism proposes that the astrocyte water channel aquaporin-4 (AQP4) is a major determinant of solute transport between the CSF and the interstitial space; however, this is controversial in part because of wide variance in experimental data on interstitial uptake of cisternally injected solutes. Here, we investigated the determinants of solute uptake in brain parenchyma following cisternal injection and reexamined the role of AQP4 using a novel constant-pressure method. In mice, increased cisternal injection rate, which modestly increased intracranial pressure, remarkably increased solute dispersion in the subarachnoid space and uptake in the cortical perivascular compartment. To investigate the role of AQP4 in the absence of confounding variations in pressure and CSF solute concentration over time and space, solutes were applied directly onto the brain surface after durotomy under constant external pressure. Pressure elevation increased solute penetration into the perivascular compartment but had little effect on parenchymal solute uptake. Solute penetration and uptake did not differ significantly between wild-type and AQP4 knockout mice. Our results offer an explanation for the variability in cisternal injection studies and indicate AQP4-independent solute transfer from the CSF to the interstitial space in mouse brain.

Treatment Model of CNS Lymphoma Using Complement-Dependent Cytotoxicity Induced by Rituximab and Autoserum.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3739-3739
Author(s):  
Yasuyuki Miyake ◽  
Yasushi Okoshi ◽  
Takayuki Machino ◽  
Shigeru Chiba
Keyword(s):  
Lateral Ventricle ◽  
Raji Cell ◽  
Technical Problem ◽  
Brain Parenchyma ◽  
Autologous Serum ◽  
Ependymal Cells ◽  
Treatment Model ◽  
Complement Dependent Cytotoxicity ◽  
The Brain

Abstract Abstract 3739 Poster Board III-675 Background Primary central nervous system lymphoma (PCNSL) is almost exclusively CD20-positive non-Hodgkin lymphoma (NHL). Although rituximab (R) is widely used for CD20-positive NHL, it is not considered to reach brain lesions effectively beyond the blood brain barrier. Intraventricule administration (ivt) of R is reported to be effective in meningeal lymphoma but the effect on lesions in the brain parenchyma seems to be limited. Recently, a case of refractory PCNSL that was successfully treated with ivt of R with autologous serum was reported (Takami A, et al. Cancer Science, 2006). Because the cerebrospinal fluid does not contain complements which exists in the serum, induction of complement-dependent cytotoxicity by ivt of R plus autoserum was speculated. To investigate this effect, we developed an animal treatment model of CNSL. Materials and methods Raji, CD20-positive Burkitt lymphoma cell line, was inoculated into the deep frontal lobe of the brain of 8-week old F344 (nru-/nru-) nude rats, using brain stereotaxic apparatus. At the same time, a cannula was placed into the ipsilateral lateral ventricle. After several days, R or control immunoglobulin (cIg), plus human serum or saline, was administrated into the lateral ventricle. Results The brain was extracted 24 hours after the last administration and frozen section was made. Human CD20-positive Raji cell tumor was also positively stained with FITC-conjugated anti-human IgG antibody when R but not cIg was administrated. Consequently, R in the lateral ventricle was considered to penetrate ependymal cells and brain parenchyma, and bound to lymphoma cells. Next, these rats were treated with ivt of R plus serum (R + Serum), cIg plus serum (cIg + Serum), or R plus saline (R + saline). These were administrated once a day from day 5 to day 9 after inoculation of Raji, and then survival was monitored. When an obvious weakness, such as marked and consecutively loss of activity or weight, was observed, these rats were euthanized and this is defined as dead day. In each case, the brain was extirpated and examined whether lymphoma existed or not. Death without lymphoma or from technical problem was excluded from the analysis. Survival of each group was analyzed by Kaplan-Meier method and log-lank test. R + Serum group had longer survival than cIg + Serum (p = 0.049). Long-term survivors were only seen in R + Serum and this group seemed to be superior to R + saline but statistical difference was not detected (p = 0.083). There were no difference between cIg + Serum and R + saline (p =0.382) and neither group had long-term survivor. Conclusion The possibility of novel treatment of CNSL with ivt of R and autoserum was shown in the rat CNSL model. To confirm this approach, clinical trials are warranted. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Modeling of Brain Shift Phenomenon for Different Craniotomies and Solid Models

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Alvaro Valencia ◽  
Benjamin Blas ◽  
Jaime H. Ortega
Keyword(s):  
Elastic Solid ◽  
Brain Parenchyma ◽  
Solid Model ◽  
Elastic Model ◽  
Brain Shift ◽  
Healthy Human ◽  
Brain Surface ◽  
Solid Models ◽  
The Difference ◽  
The Brain

This study investigates the effects of different solid models on predictions of brain shift for three craniotomies. We created a generic 3D brain model based on healthy human brain and modeled the brain parenchyma as single continuum and constrained by a practically rigid skull. We have used elastic model, hyperelastic 1st, 2nd, and 3rd Ogden models, and hyperelastic Mooney-Rivlin with 2- and 5-parameter models. A pressure on the brain surface at craniotomy region was applied to load the model. The models were solved with the finite elements package ANSYS. The predictions on stress and displacements were compared for three different craniotomies. The difference between the predictions of elastic solid model and a hyperelastic Ogden solid model of maximum brain displacement and maximum effective stress is relevant.

Ultrastructural Morphology of the Ependyma and Choroid Plexus in the African Giant Rat (Cricetomys gambianus)

2021 ◽  
Vol 65 (1) ◽  
pp. 45-53
Author(s):  
M. A. Olude ◽  
F. E. Olopade ◽  
O. A. Mustapha ◽  
S. T. Bello ◽  
A. O. Ihunwo ◽  
...  
Keyword(s):  
Choroid Plexus ◽  
Brain Parenchyma ◽  
Ependymal Cells ◽  
Apical Surface ◽  
Zonula Occludens ◽  
Cricetomys Gambianus ◽  
Functional Components ◽  
Columnar Cells ◽  
The Brain ◽  
African Giant Rat

Abstract Ependymal cells line the interface between the ventricular surfaces and the brain parenchyma. These cells, in addition to the choroid plexus, form the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) and serve important functions in the protection and regulation of brain metabolism. The African giant rat (AGR) has been used as sentinels to detect potential neuropathology arising from ecotoxicological pollutions. This study examined the lateral ventricular lining by using histology, immunohistochemistry and electron microscopy. Marked variations were observed in some regions of the ventricles which showed multi-layering of ependymal cells that differed from the typical single layered ependymal cells at the apical surface, while subependymal structures revealed indistinctive neuropil and glia following histological examinations. The ependymal cells which form the epithelial lining of the ventricles were comprised of cuboidal or low columnar cells, with the plasmalemma of abutting cells forming intercellular bridge appearing links by: tight junctions (zonula occludens), intermediate junctions (zonula adherens), desmosomes (macula adherens) and infrequent gap junctions. The choroid plexus revealed cells of Kolmer with several cilia and microvilli. The possible functional components of the ependyma and choroid plexus morphology of the AGR are discussed and thus provide a baseline for further research on the AGR brain.

Cytochemical detection of superoxide in cerebral inflammation and ischemia in vivo

1992 ◽  
Vol 263 (4) ◽  
pp. H1234-H1242 ◽  
Author(s):  
C. D. Kontos ◽  
E. P. Wei ◽  
J. I. Williams ◽  
H. A. Kontos ◽  
J. T. Povlishock
Keyword(s):  
Electron Microscopy ◽  
Ischemia Reperfusion ◽  
Brain Parenchyma ◽  
Brain Surface ◽  
Cerebral Ischemia Reperfusion ◽  
Cerebral Inflammation ◽  
Cytochemical Technique ◽  
The Brain ◽  
Dense Product

We used a cytochemical technique for the detection of superoxide in cerebral inflammation and ischemia-reperfusion in anesthetized cats. The technique is based on the oxidation of Mn2+ to Mn3+ by superoxide; Mn3+, in turn, oxidizes diaminobenzidine. The oxidized diaminobenzidine forms an osmiophilic electron-dense product that is detected by electron microscopy. The reagents, manganese chloride (2 mM) and diaminobenzidine (2 mg/ml), were placed topically on the brain surface of anesthetized cats equipped with cranial windows. Inflammation was induced by topical carrageenan with or without phorbol 12-myristate 13-acetate to activate leukocytes. In inflammation, superoxide was detected in the plasma membrane and in the phagocytic vacuoles of leukocytes. In ischemia-reperfusion, superoxide was identified in the meninges in association with blood vessels. It was located primarily in the extracellular space and occasionally in endothelial and vascular smooth muscle cells. In both inflammation and ischemia, the reaction product was eliminated by superoxide dismutase or by the omission of either manganese or diaminobenzidine. It was unaffected by sodium azide, which inhibits peroxidases. No superoxide was detected in the brain parenchyma. The findings confirm the generation of superoxide is cerebral ischemia-reperfusion and show that it is produced in cerebral vessels.

scholarly journals Generation of CSF1-Independent Ramified Microglia-Like Cells from Leptomeninges In Vitro

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 24
Author(s):  
Junya Tanaka ◽  
Hisaaki Takahashi ◽  
Hajime Yano ◽  
Hiroshi Nakanishi
Keyword(s):  
Growth Factor Receptor ◽  
Large Cell ◽  
Brain Parenchyma ◽  
Cell Aggregates ◽  
Primary Microglia ◽  
Mixed Glial Culture ◽  
Brain Surface ◽  
Del Rio ◽  
The Brain

Although del Río-Hortega originally reported that leptomeningeal cells are the source of ramified microglia in the developing brain, recent views do not seem to pay much attention to this notion. In this study, in vitro experiments were conducted to determine whether leptomeninges generate ramified microglia. The leptomeninges of neonatal rats containing Iba1+ macrophages were peeled off the brain surface. Leptomeningeal macrophages strongly expressed CD68 and CD163, but microglia in the brain parenchyma did not. Leptomeningeal macrophages expressed epidermal growth factor receptor (EGFR) as revealed by RT-PCR and immunohistochemical staining. Cells obtained from the peeled-off leptomeninges were cultured in a serum-free medium containing EGF, resulting in the formation of large cell aggregates in which many proliferating macrophages were present. In contrast, colony-stimulating factor 1 (CSF1) did not enhance the generation of Iba1+ cells from the leptomeningeal culture. The cell aggregates generated ramified Iba1+ cells in the presence of serum, which express CD68 and CD163 at much lower levels than primary microglia isolated from a mixed glial culture. Therefore, the leptomeningeal-derived cells resembled parenchymal microglia better than primary microglia. This study suggests that microglial progenitors expressing EGFR reside in the leptomeninges and that there is a population of microglia-like cells that grow independently of CSF1.

scholarly journals Deletion of the γ-Aminobutyric Acid Transporter 2 (GAT2 and SLC6A13) Gene in Mice Leads to Changes in Liver and Brain Taurine Contents

2012 ◽  
Vol 287 (42) ◽  
pp. 35733-35746 ◽  
Author(s):  
Yun Zhou ◽  
Silvia Holmseth ◽  
Caiying Guo ◽  
Bjørnar Hassel ◽  
Georg Höfner ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Rat Hepatocytes ◽  
Brain Parenchyma ◽  
Hek293 Cells ◽  
Wild Type ◽  
Taurine Transporter ◽  
Gaba Transporters ◽  
Cultured Rat Hepatocytes ◽  
Taurine Uptake ◽  
The Brain

The GABA transporters (GAT1, GAT2, GAT3, and BGT1) have mostly been discussed in relation to their potential roles in controlling the action of transmitter GABA in the nervous system. We have generated the first mice lacking the GAT2 (slc6a13) gene. Deletion of GAT2 (both mRNA and protein) neither affected growth, fertility, nor life span under nonchallenging rearing conditions. Immunocytochemistry showed that the GAT2 protein was predominantly expressed in the plasma membranes of periportal hepatocytes and in the basolateral membranes of proximal tubules in the renal cortex. This was validated by processing tissue from wild-type and knockout mice in parallel. Deletion of GAT2 reduced liver taurine levels by 50%, without affecting the expression of the taurine transporter TAUT. These results suggest an important role for GAT2 in taurine uptake from portal blood into liver. In support of this notion, GAT2-transfected HEK293 cells transported [3H]taurine. Furthermore, most of the uptake of [3H]GABA by cultured rat hepatocytes was due to GAT2, and this uptake was inhibited by taurine. GAT2 was not detected in brain parenchyma proper, excluding a role in GABA inactivation. It was, however, expressed in the leptomeninges and in a subpopulation of brain blood vessels. Deletion of GAT2 increased brain taurine levels by 20%, suggesting a taurine-exporting role for GAT2 in the brain.

Membrane structure in mammalian astrocytes: a review of freeze-fracture studies on adult, developing, reactive and cultured astrocytes

1981 ◽  
Vol 95 (1) ◽  
pp. 35-48
Author(s):  
D. M. Landis ◽  
T. S. Reese
Keyword(s):  
Cerebrospinal Fluid ◽  
Membrane Structure ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Brain Parenchyma ◽  
Specific Pattern ◽  
Cultured Astrocytes ◽  
Fluid Compartments ◽  
Polygonal Particle ◽  
The Brain

The application of freeze-fracture techniques to studies of brain structure has led to the recognition of two unsuspected specializations of membrane structure, each distributed in a specific pattern across the surface of astrocytes. ‘Assemblies’ (aggregates of uniform, small particles packed in orthogonal array into rectangular or square aggregates) are found to characterize astrocytic plasma membranes apposed to blood vessels or to the cerebrospinal fluid at the surface of the brain. These particle aggregates are much less densely packed in astrocytic processes in brain parenchyma. Assemblies are not fixation artifacts, have been shown to extend to the true outer surface of the membrane, are remarkably labile in the setting of anoxia, and are at least in part protein. The function of assemblies is unknown, but their positioning suggests that they may have a role in the transport of some material into or out of the blood and cerebrospinal fluid compartments. A second specialization of intramembrane particle distribution, the polygonal particle junction, links astrocytic processes at the surface of the brain, and also links proximal, large caliber astrocytic processes in brain parenchyma. The function of this membrane specialization also is unknown, but it may subserve a mechanical role.

scholarly journals AQP-4 AND ITS ROLE IN MAINTAINING THE HYDRIC BALANCE IN THE BRAIN

2017 ◽  
Vol 16 (2) ◽  
pp. 39-45
Author(s):  
Elena-Silvia Popescu ◽  
◽  
Daniel Pirici ◽  
Sabina Andrada Zurac ◽  
Daniela Adriana Ion ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Protective Role ◽  
Brain Parenchyma ◽  
Urine Concentration ◽  
Main Role ◽  
Osmotic Gradient ◽  
Vasogenic Oedema ◽  
Nervous Impulse ◽  
Bidirectional Transport ◽  
The Brain

Aquaporins are a vast family of channel proteins whose main role is the bidirectional transport, depending on the osmotic gradient, of water across the lipid membranes, which have low permeability for this solvent. The aquaporins are also involved in the lipid metabolism, the cell proliferation and migration processes, the transport of glycerol, neuroexcitation and epithelial fluids secretion, having numerous roles such as ensuring the water transport in the central nervous system, the production of CSF, aqueous humor and saliva, epithelial hydration, urine concentration and nervous impulse transmission. Up to now, in mammals there have been identified 13 types of aquaporins, each of them annotated from 0 to 12 (Aqp 0 – Aqp 12). Of these, aquaporin-4 (AQP-4) – located in the astroglia - is the most abundant aquaporin in the brain. Although this type of aquaporin is also present inside the brain parenchyma, especially in the astroglial processes lining the neuronal synapses, AQP-4 is mainly located in the astroglial end-feet adjacent to the ependymocyes or endothelial cells, where its main role is to ensure the bidirectional transport of water between the astroglia and the cerebrospinal fluid (CSF) or blood vessels. The presence of AQP-4 on the surface of astroglial processes promotes, in the initial stages of ischemia, the formation of the cytotoxic oedema, but has a protective role against vasogenic oedema. This review aims to describe the roles of AQP-4, and especially the role that this protein has in maintaining the hydric balance in the brain.

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