143 resultados para Astrocyte


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In our previous work we developed a successful protocol to pattern the human hNT neuron (derived from the human teratocarcinoma cell line (hNT)) on parylene-C/SiO2 substrates. This communication, reports how we have successfully managed to pattern the supportive cell to the neuron, the hNT astrocyte, on such substrates. Here we disseminate the nanofabrication, cell differentiation and cell culturing protocols necessary to successfully pattern the first human hNT astrocytes to single cell resolution on parylene-C/SiO2 substrates. This is performed for varying parylene strip widths providing excellent contrast to the SiO2 substrate and elegant single cell isolation at 10μm strip widths. The breakthrough in patterning human cells on a silicon chip has widespread implications and is valuable as a platform technology as it enables a detailed study of the human brain at the cellular and network level.

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In our seminal work, we reported how the biomaterial Parylene-C has the unique ability to coerce neurons and glial cells to migrate to and then grow in straight lines along serum coated rectangular parylene-C structures mounted on an oxidised silicon substrate. In this brief communication, we report how astrocyte cell bodies, from the dissociated postnatal rat hippocampus, can now to be successfully localised on an ultra-thin 13nm layer of parylene-C mounted on oxidised silicon (Figure 1). What is extremely interesting about this finding is that the astrocyte processes extended mainly in horizontal and vertical directions from the cell body thus creating a regular lattice network of individual cells. In addition, they comfortably extended a 50μm gap (equivalent to ~ 10 cell body diameters) to connect to adjacent astrocytes on neighbouring Parylene-C structures. This was found to occur repeatedly on circular geometries of 20μm diameter. In comparison to our previous work [1], we have decreased the thickness of the parylene-C structures by a factor of 10, to allow such technology to be able to be utilised for passive electrode design that requires extremely thin structures such as these. Thus, being able to culture astrocytes in regular lattice networks will pave the way for precise monitoring and stimulation of such ensembles via multi-electrode arrays, allowing a closer insight into their dynamic behaviour and their network properties.

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Proteolytic enzymes comprise approximately 2 percent of the human genome [1]. Given their abundance, it is not surprising that proteases have diverse biological functions, ranging from the degradation of proteins in lysosomes to the control of physiological processes such as the coagulation cascade. However, a subset of serine proteases (possessing serine residues within their catalytic sites), which may be soluble in the extracellular fluid or tethered to the plasma membrane, are signaling molecules that can specifically regulate cells by cleaving protease-activated receptors (PARs), a family of four G-protein-coupled receptors (GPCRs). These serine proteases include members of the coagulation cascade (e.g., thrombin, factor VIIa, and factor Xa), proteases from inflammatory cells (e.g., mast cell tryptase, neutrophil cathepsin G), and proteases from epithelial tissues and neurons (e.g., trypsins). They are often generated or released during injury and inflammation, and they cleave PARs on multiple cell types, including platelets, endothelial and epithelial cells, myocytes, fibroblasts, and cells of the nervous system. Activated PARs regulate many essential physiological processes, such as hemostasis, inflammation, pain, and healing. These proteases and their receptors have been implicated in human disease and are potentially important targets for therapy. Proteases and PARs participate in regulating most organ systems and are the subject of several comprehensive reviews [2, 3]. Within the central and peripheral nervous systems, proteases and PARs can control neuronal and astrocyte survival, proliferation and morphology, release of neurotransmitters, and the function and activity of ion channels, topics that have also been comprehensively reviewed [4, 5]. This chapter specifically concerns the ability of PARs to regulate TRPV channels of sensory neurons and thereby affect neurogenic inflammation and pain transmission [6, 7].

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Although the adult brain contains neural stem cells (NSCs) that generate new neurons throughout life, these astrocyte-like populations are restricted to two discrete niches. Despite their terminally differentiated phenotype, adult parenchymal astrocytes can re-acquire NSC-like characteristics following injury, and as such, these 'reactive' astrocytes offer an alternative source of cells for central nervous system (CNS) repair following injury or disease. At present, the mechanisms that regulate the potential of different types of astrocytes are poorly understood. We used in vitro and ex vivo astrocytes to identify candidate pathways important for regulation of astrocyte potential. Using in vitro neural progenitor cell (NPC)-derived astrocytes, we found that exposure of more lineage-restricted astrocytes to either tumor necrosis factor alpha (TNF-α) (via nuclear factor-κB (NFκB)) or the bone morphogenetic protein (BMP) inhibitor, noggin, led to re-acquisition of NPC properties accompanied by transcriptomic and epigenetic changes consistent with a more neurogenic, NPC-like state. Comparative analyses of microarray data from in vitro-derived and ex vivo postnatal parenchymal astrocytes identified several common pathways and upstream regulators associated with inflammation (including transforming growth factor (TGF)-β1 and peroxisome proliferator-activated receptor gamma (PPARγ)) and cell cycle control (including TP53) as candidate regulators of astrocyte phenotype and potential. We propose that inflammatory signalling may control the normal, progressive restriction in potential of differentiating astrocytes as well as under reactive conditions and represent future targets for therapies to harness the latent neurogenic capacity of parenchymal astrocytes.

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Despite the favorable treatment of cranial nerve neuropathology in adulthood, some cases are resistant to therapy leading to permanent functional impairments In many cases, suitable treatment is problematic as the therapeutic target remains unknown Basic fibroblast growth factor (bFGF, FGF 2) is involved in neuronal maintenance and wound repair following nervous system lesions It is one of few neurotrophic molecules acting in autocrine, paracrine and intracrine fashions depending upon specific circumstances Peripheral cranial somatic motor neurons, i e hypoglossal (XII) neurons, may offer a unique opportunity to study cellular FGF 2 mechanisms as the molecule is present in the cytoplasm of neurons and in the nuclei of astrocytes of the central nervous system FGF-2 may trigger differential actions during development, maintenance and lesion of XII neurons because axotomy of those cells leads to cell death during neonatal ages, but not in adult life Moreover, the modulatory effects of astroglial FGF 2 and the Ca+2 binding protein S100 beta have been postulated in paracrine mechanisms after neuronal lesions In our study, adult Wistar rats received a unilateral crush or transection (with amputation of stumps) of XII nerve, and were sacrificed after 72 h or 11 days Brains were processed for immunohistochemical localization of neurofilaments (NF), with or without counterstaining for Nissl substance, ghat fibrillary acidic protein (GFAP, as a marker of astrocytes), S100 beta and FGF-2 The number of Nissl positive neurons of axotomized XII nucleus did not differ from controls The NF immunoreactivity increased in the perikarya and decreased in the neuropil of axotomized XII neurons 11 days after nerve crush or transection An astrocytic reaction was seen in the ipsilateral XII nucleus of the crushed or transected animals 72 h and 11 days after the surgery The nerve lesions did not change the number of FGF-2 neurons in the ipsilateral XII nucleus, however, the nerve transection increased the number of FGF-2 ghat profiles by 72 h and 11 days Microdensitometric image analysis revealed a short lasting decrease in the intensity of FGF 2 immunoreactivity in axotomized XII neurons by 72 h after nerve crush or transection and also an elevation of FGF-2 in the ipsilateral of ghat nuclei by 72h and 11 days after the two lesions S100 beta decreased in astrocytes of 11-day transected XII nucleus The two-color immunoperoxidase for the simultaneous detection of the GFAP/FGF-2 indicated FGF-2 upregulation in the nuclei of reactive astrocytes of the lesioned XII nucleus Astroglial FGF-2 may exert paracrine trophic actions in mature axotomized XII neurons and might represent a therapeutic target for neuroprotection in peripheral nerve pathology (C) 2009 Elsevier GmbH All rights reserved

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In this study we evaluated whether administration of stem cells of neural origin (neural precursor cells, NPCs) could be protective against renal ischemia-reperfusion injury (IRI). We hypothesized that stem cell outcomes are not tissue-specific and that NPCs can improve tissue damage through paracrine mechanisms, especially due to immunomodulation. To this end, Wistar rats (200-250 g) were submitted to 1-hour ischemia and treated with NPCs (4 x 10(6) cells/animal) at 4 h of reperfusion. To serve as controls, ischemic animals were treated with cerebellum homogenate harvested from adult rat brain. All groups were sacrificed at 24 h of reperfusion. NPCs were isolated from rat fetus telencephalon and cultured until neurosphere formation (7 days). Before administration, NPCs were labeled with carboxyfluorescein diacetate succinimydylester (CFSE). Kidneys were harvested for analysis of cytokine profile and macrophage infiltration. At 24 h, NPC treatment resulted in a significant reduction in serum creatinine (IRI + NPC 1.21 + 0.18 vs. IRI 3.33 + 0.14 and IRI + cerebellum 2.95 + 0.78mg/dl, p < 0.05) and acute tubular necrosis (IRI + NPC 46.0 + 2.4% vs. IRI 79.7 + 14.2%, p < 0.05). NPC-CFSE and glial fibrillary acidic protein (GFAP)-positive cells (astrocyte marker) were found exclusively in renal parenchyma, which also presented GFAP and SOX-2 (an embryonic neural stem cell marker) mRNA expression. NPC treatment resulted in lower renal proinflammatory IL1-beta and TNF-alpha expression and higher anti-inflammatory IL-4 and IL-10 transcription. NPC-treated animals also had less macrophage infiltration and decreased serum proinflammatory cytokines (IL-1 beta, TNF-alpha and INF-gamma). Our data suggested that NPC therapy improved renal function by influencing immunological responses. Copyright (C) 2009 S. Karger AG, Basel

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Cells are able to detect and respond to mechanical cues from their environment. Previous studies have investigated this mechanosensitivity on various cell types, including neural cells such as astrocytes. In this study, we have carefully optimized polyacrylamide gels, commonly used as compliant growth substrates, considering their homogeneity in surface topography, mechanical properties, and coating density, and identified several potential pitfalls for the purpose of mechanosensitivity studies. The resulting astrocyte response to growth on substrates with shear storage moduli of G` = 100 Pa and G` = 10 kPa was then evaluated as a function of coating density of poly-D-lysine using quantitative morphometric analysis. Astrocytes cultured on stiff substrates showed significantly increased perimeter, area, diameter, elongation, number of extremities and overall complexity if compared to those cultured on compliant substrates. A statistically significant difference in the overall morphological score was confirmed with an artificial intelligence-based shape analysis. The dependence of the cells` morphology on PDL coating density seemed to be weak compared to the effect of the substrate stiffness and was slightly biphasic, with a maximum at 10-100 mu g ml(-1) PDL concentration. Our finding suggests that the compliance of the surrounding tissue in vivo may influence astrocyte morphology and behavior.

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Cell culture analyses of growth, morphology and apoptosis commonly require counting of different cell types stained with antibodies to discriminate between them. Previously, we reported the use of l-Leucine methyl ester (l-LME) to prepare purified cultures of type 1 astrocytes with minimal microglia, and staining by GFAP and CD antibodies, respectively. Here, we demonstrate a novel use of acridine orange (AO) for rapid discrimination between these cell types using fluorescence microscopy. AO accumulates in the lysosomes and also binds strongly to nuclear DNA and cytoplasmic/nucleolar RNA. Microglia may contain abundant lysosomes due to known roles in homeostasis and immune response. AO staining of lysosomes was tested at a range of concentrations, and 2.5 μg/mL was most suitable. In agreement with previous reports, microglia treated with AO showed very intense yellow, orange or red granular cytoplasmic staining of lysosomes. Microglia contain a substantially higher number of lysosomes than astrocytes, which have a variable amount. We measured the microglia population at 5.14 ± 0.50% in mixed cultures. Thus, these results show AO is a novel discriminatory marker, as microglia were easily observed and counted in clumps on top of the monolayer of astrocytes, providing a rapid alternative to time-consuming and costly antibody-based assays.

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A protocol for culturing mammalian type 1 astrocytic cells, using female post-natal rat cerebral cortical tissue, was established and refined for use in steroidogenic metabolic studies incorporating progestin radioisotopes. Cultures were characterised for homogeneity using standard morphological and immunostaining techniques. Qualitative and quantitative studies were conducted to characterise the progesterone (P) metabolic pathways present in astrocytes in vitro. Of particular interest was the formation of the P metabolite, 5á-pregnan-3á-ol-20-one (THP). THP is a GABA(A) receptor agonist, believed to play a vital role in neural functioning and CNS homeostasis. One aim of this study was to observe any modulatory effects selected neuroactive ligands have on the conversion of P into THP, in an attempt to link astrocytic steroidogenesis with neuronal control. In qualitative studies, chromatographic procedures were used to establish the progestin profile of cerebral cortical astrocytes. Tritiated P, DHP (5á-pregnan-3,20-dione) and THP incurbates were preliminary fractionated by either normal phase (NP) or reverse phase (RP) high performance liquid chromatography (HPLC). The radiometabolites associated with each fraction were further chromatographed, before and/or after chemical derivatistation, by the aforemention HPLC procedures and thin layer chromatography (TLC). Steroid radiometabolites were tentatively identified by comparing their chromatographic mobility with authentic steroids. The identity of the main putative 5á-reduced P metabolities, DHP, THP and 5á-pregnan-3á,20á-diol (20áOH-THP) were further confirmed by isotopic dilution analysis. Their conclusive identification, along with the tentative identification of 20á-hydroxypreg-4-en-3-one (20áOH-P) and 20á-hydroxy-5á-pregnan-3-one (20áOH-DHP), verify the localisation of 5á-reductase, 3á-hydroxy steroif oxidoreductase (HSOR), and 20á-HSOR activity in the cultured astrocytes utilised in this study programme. Other minor metabolites detected were tentatively identified, including 5á-pregnan-3á,21-diol-20-one (THDoc), indicating the presence of 21-hydroxylase enzymatic activity. THDoc, like THP, is a GABA(A) receptor agonist. The chemical and physical characterisation of several yet unidentified progestin metabolites, associated with a highly polar RP HPLC fraction (designated RP peak 1*), indicate the presence of one or more extra hydroxylase enzymes. Quantitative analysis included a preliminary study. In this study, the percentage yields of radiometabolites formed in cultures incubated with increasing substrate concentrations of (3)H-P for 24 hours were determined. At the lower concentrations examined (ie 0.5 to 50nM), the metabolites associated with the polar RP HPLC fraction (RP peak 1*) collectively have the highest percentage yield. They are subsequently considered metabolic end products of degradative catabolic P pathways. The percentage yield of THP peaks in the medium concentration ranges (ie 5 to 500nM), whereas DHP remains fairly static at a low level with increasing concentration. Both DHP and THP are considered metabolic pathway intermediates. The percentage yield of 20áOH-THP continues to increase with increasing concentration over 5nM, superseding THP approaching the highest concentration examined (5000nM). This indicated the formation of 20áOH-THP does not occur entirely via THP. 20áOH-THP also possibly serves as the direct intermediate in the formation of the main radiometabolites associated with RP peak 1*. A time/yield study incorporating incubation times from one to 24 hours was also conducted. The full array of radiometabolites (individually or in groups) formed in astrocyte cultures incubated with 50nM tritiated P, DHP of THP, were assayed. Cultures were observed to rapidly convert any DHP into THP, showing astrocytic 3á-HSOR activity is very high. The study also showed 5á-reduction (ie the conversation of P into DHP) is the rate limiting reaction in the two step conversion of P into THP. 5á-Reduction also appears to be a rate limiting step in the formation of 20á-hydroxylated metabolites in astrocytes. Cultures incubated with the tritiated 5á-reduced pregnanes from one to four hours form greater quantities to 20á-hydroxylated radiometabolites compared to cultures incubated with (3)H-P. The time yield/studies also provided further evidence the unidentified polar radiometabolites associated with RP peak 1* are metabolic end products. For the P and DHP incubates, the collective formation of the aforementioned polar radiometabolites initially lags behind the formation of THP. As the formation of the latter begins to plateau with increasing time between four to 24 hours, the net yield of radiometabolites associated with RP peak 1* continues to rise. The time/yield studies also indicate 5á-reduction and perhaps 3á-hydroxylation are pre-requisite steps in the formation of the polar metabolites. Cultures incubated with the 5á-reduced progestins from one to four hours form higher yields of the radiometabolites associated with RP peak 1* compared to cultures incubated with P as substrate. The net yields of the radiometabolites associated with RP peak 1* for cultures incubated with THP were substantially higher compared to cultures incubated with DHP after equivalent times. The effect selected neuroligands have on the yield of radiometabolites formed by cultured astrocytes incubated with 50nM (3)H-P was also examined. Dibutyryl cyclic adenosine monophosphate (DBcAMP), not actually a neuroligand per se, but an analog of the intracellular secondary messenger cAMP, was also utilised in these studies. The inhibitory neurotransmitter ă-amino-nbutyric acid (GABA), DBcAMP and isoproterenol (a â-adrenergic receptor agonist) all quickly induce a transient but substantial increase in 20á-HSOR activity in cultured astrocytes. Cultures pretreated with these three compounds (10, 20 and 1µM respectively) form substantially higher yields of 20á-hydroxylated metabolites, including 20áOH-THP (between 200 to 580% greater), when incubated with 50nM (3)H-P for one to four hours. These increases also coincide with increases in the net yield of metabolites formed (by 16 to 48%). The same pre-treated cultures form significantly lower yields of THP, by 25 to 41%, after one hour. This is most likely due to the increased metabolism of any formed THP into 20áOH-THP. Octopamine (an á-adrenergic agonist) only induces a slight increase in 20á-HSOR activity, having relatively little effect on the yield of 20áOH-THP formed. Pretreatment with octopamine induces a significant increase in the yield of THP for cultures incubated with (3)H-P for four hours (by 24%). The increase in THP formation appears to be due to an increase in 3á-HSOR activity, as judged by the concomitant drop in the yield of the 5á-reduced, 3-keto substrates. An increase in 5á-reductase activity cannot be excluded however. Isoproterenol appears to induce an increase in 5á-reductase activity as isoproterenol appears to induce an increase in 5á-reductase activity as isoproterenol one and four hour incubates have higher yields of DHP. This is in contrast to the other three incubates. After 12 hours, all incubates have higher yields of THP (15-30%).

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The chondroitin sulfate proteoglycans (CSPGs) aggrecan, versican, and brevican are large aggregating extracellular matrix molecules that inhibit axonal growth of the mature central nervous system (CNS). ADAMTS proteoglycanases, including ADAMTS4 and ADAMTS5, degrade CSPGs, representing potential targets for ameliorating axonal growth-inhibition by CSPG accumulation after CNS injury. We investigated the proteolysis of CSPGs in mice homozygous for Adamts4 or Adamts5 null alleles after spinal cord injury (SCI). ADAMTS-derived 50-60 kDa aggrecan and 50 kDa brevican fragments were observed in Adamts4-/-, Adamts5-/-, and wt mice but not in the sham-operated group. By contrast Adamts4-/- and Adamts5-/- mice were both protected from versican proteolysis with an ADAMTS-generated 70 kDa versican fragment predominately observed in WT mice. ADAMTS1, ADAMTS9, and ADAMTS15 were detected by Western blot in Adamts4-/- mice' spinal cords after SCI. Immunohistochemistry showed astrocyte accumulation at the injury site. These data indicate that aggrecan and brevican proteolysis is compensated in Adamts4-/- or Adamts5-/- mice by ADAMTS proteoglycanase family members but a threshold of versican proteolysis is sensitive to the loss of a single ADAMTS proteoglycanase during SCI. We show robust ADAMTS activity after SCI and exemplify the requirement for collective proteolysis for effective CSPG clearance during SCI.

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Autism is a disorder of unknown etiology. There are few FDA approved medications for treating autism. Co-occurring autism and epilepsy is common, and glutamate antagonists improve some symptoms of autism. Ceftriaxone, a beta-lactam antibiotic, increases the expression of the glutamate transporter 1 which decreases extracellular glutamate levels. It is hypothesized that modulating astrocyte glutamate transporter expression by ceftriaxone or cefixime might improve some symptoms of autism. This case report of a child with autism and epilepsy suggests a decrease in seizures after taking cefixime

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The thalamus plays an important role in the sensorial processing information, in this particular case, the visual information. Several neuronal groups have been characterized as conductors and processors of important sensorial information to the cerebral cortex. The lateral geniculate complex is one to them, and appears as a group very studied once it is responsible, in almost all totality, for the processing of visual information. Among the nuclei that constitute the lateral geniculate complex we highlight the dorsal lateral geniculate nucleus of the thalamus (DLG), the main thalamic relay for the visual information. This nucleus is located rostral and lateral to medial geniculate nucleus and ventral to thalamic pulvinar nucleus in most of the mammals. In the primates humans and non-humans, it presents as a laminate structure, arranged in layers, when observed in coronal sections. The objective of this work was to do a mapping of the retinal projections and a citoarchictetonic and neurochemical characterization of DLG in the marmoset (Callithrix jacchus), a New World primate. The retinal projections were traced by anterograde transport of subunit b of cholera toxin (CTb), the citoarchicteture was described by Nissl method, and to neurochemical characterization immunohistochemicals technical were used to examine the main neurotransmitters and neuroatives substances present in this neural center. In DGL of marmoset thalamus, in coronal sections labeled by Nissl method, was possible to visualize the division of this nucleus in four layers divided in two portions: magnocellular and parvocellular. The retinal projections were present being visualized fibers and terminals immunorreactives to CTb (IR-CTb) in the DLG ipsilateral and contralateral. And through the immunohistochemicals techniques was observed that DLG contain cells, fibers and/or terminals immunoreactives against neuronal nuclear protein, subunits of AMPA 15 glutamate receptors (GluR1, GluR2/3, GluR4), choline acetyltransferase, serotonin, glutamic acid decarboxylase, binding calcium proteins (calbindin, parvalbumin and calretinin), vasopressin, vasoactive intestinal polypeptide, and an astrocyte protein, glial fibrillary acidic protein.

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BACKGROUND: The N-methyl-D-aspartate receptor antagonist ketamine and its active enantiomer, S(+)-ketamine, have been injected in the epidural and subarachnoid spaces to treat acute postoperative pain and relieve neuropathic pain syndrome. In this study we evaluated the effects of a single dose of preservative-free S(+)-ketamine, in doses usually used in clinical practice, in the spinal cord and meninges of dogs.METHODS: Under anesthesia (IV etomidate (2 mg/kg) and fentanyl (0.005 mg/kg), 16 dogs (6 to 15 kg) were randomized to receive a lumbar intrathecal injection (L5/6) of saline solution of 0.9% (control group) or S(+)-ketamine 1 mg/kg(-1) (ketamine group). All doses were administered in a volume of 1 mL over a 10-second interval. Accordingly, injection solution ranged from 0.6% to 1.5%. After 21 days of clinical observation, the animals were killed; spinal cord, cauda equine root, and meninges were removed for histological examination with light microscopy. Tissues were examined for demyelination (Masson trichrome), neuronal death (hematoxylin and eosin) and astrocyte activation (glial fibrillary acidic protein).RESULTS: No clinical or histological alterations of spinal tissue or meninges were found in animals from either control or ketamine groups.CONCLUSION: A single intrathecal injection of preservative-free S(+)-ketamine, at 1 mg/kg-1 dosage, over a concentration range of 6 to 15 mg/mL injected in the subarachnoid space in a single puncture, did not produce histological alterations in this experimental model. (Anesth Analg 2012;114:450-55)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)