Navegando por Palavras-chave "astrocytes"

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    Apoptotic effect of ethanol is potentiated by caffeine-induced calcium release in rat astrocytes
    (Elsevier B.V., 2006-01-30) Hirata, H.; Machado, L. S.; Okuno, C. S.; Brasolin, A.; Lopes, G. S.; Smaili, Soraya Soubhi [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In this study, we investigated agents that increased intracellular calcium levels and their correlation with apoptotic cell death induction. We used rat astrocytes to investigate the increase in cytosolic Ca2+, (Ca-c(2+)) and apoptosis induction by drugs that mobilize Ca2+ from different sources. We observed that thapsigargin (Thap), caffeine (Caff) and FCCP which caused similar increases in Ca-c(2+) levels (30-40%), also induced similar apoptotic rates (30-35%). On the other hand, antimycin (Anti), staurosporine (STS) and ethanol (Eth) promoted higher increases in Ca-c(2+) (55-65 %) and higher apoptotic rates (55-85%). Eth induced cell death in a concentration- and time-dependent manner. After treatment with Eth plus Caff for 6, 12 and 24 h, these effects were strongly potentiated. Results suggest that there might be a correlation between Ca-c(2+) increase and the rate of apoptosis. It is possible that Eth induces cell death by activation of more than one pathway and Ca-c(2+) might be one of the elements involved. the present work indicates that Ca-c(2+) can potentiate death by ethanol in rat astrocytes. (c) 2005 Elsevier Ireland Ltd. All rights reserved.
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    Expression of nestin in the hippocampal submitted to the pilocarpine model formation of rats of epilepsy
    (Elsevier B.V., 2005-03-01) Scorza, C. A.; Arida, R. M.; Cavalheiro, E. A.; Naffah-Mazzacoratti, M. G.; Scorza, F. A.; Universidade Federal de São Paulo (UNIFESP); Univ Mogi Cruzes
    Nestin is an embryonic intermediate filament component protein, transiently expressed by the immediate precursor cells of neurons and glia, during brain development. We studied the nestin distribution in the hippocampal formation of rats submitted to pilocarpine model of epilepsy. Animals were studied during the acute, silent and chronic phases. Rats from control and acute groups presented absence of nestin-immunoreactivity (IR) in the hippocampal cells. in contrast, cells from this region presented strong nestin IR during the silent phase (3 and 7 days after status epilepticus (SE) onset), disappearing 14 days after SE. Nestin IR cells were scattered expressed in all hippocampal formation during the chronic phase. Almost all nestin IR cells exhibited glial fibrillary acidic protein (GFAP), which seems to revert to a more primitive glial form, as part of an adaptive response, transiently re-expressing phenotypic features typical of earlier stages of glial development. the re-expression of this developmental protein in the damaged cerebral tissue suggests that nestin may play an important role in the reconstruction of the glial cytoskeleton and/or remodeling events occurring in the pilocarpine model of epilepsy. Understanding how astrocytes influence network function in the injured hippocampus may, therefore, provide insight into epileptogenic mechanisms. (C) 2004 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
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    Synthesis of elastic microfibrillar components fibrillin-1 and fibrillin-2 by human optic nerve head astrocytes in situ and in vitro
    (Academic Press Ltd, 2000-05-01) Pena, JDO; Mello, PAA; Hernandez, M. R.; Washington Univ; Universidade Federal de São Paulo (UNIFESP)
    The purpose of this study was to identify elastic microfibrillar components fibrillin-1 and fibrillin-2 in optic nerve heads of adult normal and glaucomatous subjects. in cultured optic nerve head astrocytes (type 1B astrocytes), as well as fibrillin-1 in fetal optic nerve heads. To characterize synthesis and gene expression of microfibrillar proteins in human optic nerve heads and cultured type 1B astrocytes, light microscopy immunohistochemistry, in situ hybridization, and RT-PCR or Northern blots were performed. Our results demonstrated that fibrillin-1 was associated with blood vessels, astrocytes in the glial columns and cribriform plates, and with astrocyte processes in the nerve bundles in all samples. in glaucomatous optic nerves there was enhanced fibrillin-1 immunoreactivity, especially surrounding blood Vessels. Fibrillin-2 was localized primarily to brood Vessels in all samples, without qualitative differences between normal and glaucomatous samples, in fetal optic nerve heads fibrillin-1. mRNA was localized to glial cells and to the blood vessel walls, in adult optic nerve heads, there was little fibrillin-1 mRNA as detectable by in situ hybridization and RT-PCR. There was no detectable upregulation of fibrillin-1 mRNA in glaucoma. in cultured type 1B astrocytes, fibrillin-1 staining was mostly pericellular.. There was little fibrillin-2 immunoreactivity. in conclusion astrocytes from the optic nerve head deposit elastic microfibrillar components in situ and in vitro, with a predominance of fibrillin-1. Upregulation of fibrillin-1 mRNA was not observed in glaucoma, suggesting that increased transcription may occur early in the disease process. Cultures of type 1B astrocytes from the optic nerve head provides a useful model to study mechanisms regulating the interactions of elastin and the microfibrils in optic nerve head astrocytes. (C) 2000 Academic Press.