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Navegando por Assunto "Redes perineuronais"

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    Aumento da ativação neuronal e de marcação de BDNF após degradação das redes perineuronais em modelo experimental de privação sensorial
    (Universidade Federal do Pará, 2016-09-23) AGUIAR, Gisele Priscila Soares de; PEREIRA JÚNIOR, Antônio; http://lattes.cnpq.br/1402289786010170; BAHIA, Carlomagno Pacheco; http://lattes.cnpq.br/0910507988777644
    The central nervous system (CNS) has the ability to processing and store information collected from the environment, and modifies and adapt under environmental stimuli diversity. However, It has low regeneration capacity after injury or neurodegenerative disease. Several works are demonstrating cellular and molecular mechanisms implicated in CNS plasticity, such as chondroitin sulfate glycosaminoglycans (GAGs-SC) important components of the extracellular matrix from nervous tissue, responsible for synaptic stabilization, toconcentrateof growth factors and ions around neurons. Removing CSPG of the nervous tissue, we can (re)opens a potential plasticity window in the CNS. The goal of our work is to evaluate the influence of removal of GAGs-SC on neuronal activity, via cFos immunolabeling, and BDNF proteins levels at the barrel cortex, under an experimental model of sensory deprivation (vibrissectomy) during critical period of plasticity. To do that, we used 18 rats (Rattus novergicus), Wistar lineage, submitted to the removal of all whiskers from their right snout (vibrissectomy) since first day of life (P0) until the end of critical period of plasticity (P30). The 40 days deprived animals received epidural polimer implant of Elvax, previously saturated with chondroitinase ABC (ChABC, to degraded the extracellular matrix) or with bovine albumin serum(BSA, control), on the barrel cortex of contralateral cerebral hemisphere to the sensory deprivation (left). The animals were perfused 10 (P50) or 20 days (P60) after Elvax implant. Our results shown that the animals submitted to the sensory deprivation, during critical period of plasticity of S1, and to GAGsSC degradation presents modification in perineuronal net (PNNs) characteristics when compared to control animals, at P50. Those animals also presents increase in cFos labeled cells (mainly at the granular layer of S1) and in BDNF labeled cells at the deprived PMBSF, both seen in 10 (P50) as 20 days (P60) after Elvax implant saturated with ChABC. In this way, we concluded that GAGs-SC removal induced local plasticity, evoking changes in cortical activity and BDNF expression at the deprived PMBSF, even 30 days after critical period of plasticity ended at S1.
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    Curso temporal da degradação e restauração de redes perineuronais após a ação da enzima chabc entregue via implante de biomembrana no córtex cerebral de ratos
    (Universidade Federal do Pará, 2020-03-18) REIS, Rafaela Martins; BAHIA, Carlomagno Pacheco; http://lattes.cnpq.br/0910507988777644; https://orcid.org/0000-0003-3794-4710
    The chondroitin sulfate proteoglycans (CSPGs) founded on the extracellular matrix (ECM) of nervous tissue are the main components related to the restriction of neuroplasticity. When condenserd, they form the perineuronal nets (PNNs) and their appearance coincides with the end of the critical period of plasticity and reduction of the reorganization potencial of the central nervous system (CNS). The degradation of PNNs by the enzyme chondroitinase ABC has been used as a tool for reopening periods of neuroplasticity in adult nervous system.. In this work, we analyzed the temporal dynamics of PNNs degradation and restoration in the primary somesthetic cortex (S1) after degradation by the enzyme ChABC in an in vivo experimental model using a biomembrane vehicle for focal delivery and without damaging nervous tissue. In this way, we used adult Wistar rats that were submitted to the implantation of the biomembrane made with ethylene-vinyl-acetate saturated with the enzyme ChABC, with 1, 3 and 7 days of survival time after implantation, using the non implanted side cerebral hemisphere as a control. Our results demonstrated that degradation via implantation of the biomembrane saturated with ChABC was efficient from day 1, with a drastic reduction in the implanted hemisphere (LH) of mature PNNs. There was also a significant increase in the number of immature PNNs in the HD even 7 days after implantation. Neither the biomembrane or the enzyme triggered signs of a neuroinflammatory process or glial activation, but the removal of ECM components interfered with the immunostaining of nerve cells 7 days after the implantation of the biomembrane with ChABC. Therefore, we concluded that the ethylene-vinyl-acetate polymer biomembrane was efficient for focal delivery of the ChABC enzyme and promoted degradation of PNNs in the S1 area of adult rats, did not cause mechanical damage to the nervous tissue, nor activated glial reactivity and the area of enzymatic degradation decreases over time (from 1 to 7 days).
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    Plasticidade aumentada no córtex pré-frontal de ratos com a remoção de redes perineuronais
    (Universidade Federal do Pará, 2016-11-01) RODRIGUES, Klebson de Jesus Araujo; BAHIA, Carlomagno Pacheco; http://lattes.cnpq.br/0910507988777644; PEREIRA JÚNIOR, Antônio; http://lattes.cnpq.br/1402289786010170
    Aging is associated with decreasing brain plasticity, especially after the closure of the critical periods of plasticity (a sensitive limited period in life of elevated brain plasticity). Some brain regions may be particularly affected by aging, such as prefrontal cortex (PFC), which has a key role in the organization of higherorder cognitive aspects, the executive functions, including attention, set-shifting, working memory, decision making, etc. Decline of plasticity in the PFC and the brain is attributed mainly to the appearance of a structure called perineuronal net (PNNs) which enwraps the cell body and dendrites of many classes of neurons. PNNs are extracellular matrix structures consisting of chondroitin sulfate proteoglycans, hyaluronan, link proteins and tenascin, and are involved in the control of experience-dependent cortical plasticity and the closure of critical periods. Degradation of PNNs with the enzyme Chondroitinase ABC (ChABC) restores juvenile forms of plasticity in the adult brain. Here, we examined the developmental time course of PNN formation in the medial PFC (mPFC) of male rats ranging in age from the seventh postnatal day (PND) to 11 months. We used the lectin Vicia villosa agglutinin that binds to glycosaminoglycan chains present in the PNNs. We also investigated whether the digestion of PNNs by bilateral injection of ChABC in the mPFC may open a new window of increased plasticity in adult rats, evaluated by two executive function tests: object recognition and spontaneous alternation. We found that immature PNNs were observed in PND 20 animals, but mature PNNs were seen only after PND 75-90 and a mature form appeared around 5 months of age. In addition, our results showed that enzymatic PNN removal promoted a significant increase in performance in the ChABC-treated animals in both behavioral tests. The present study reveals for the first time the temporal development of PNN formation in the rat mPFC. We also show that the degradation of PNNs with ChABC not only promotes plasticity but also potentiates cognitive abilities in adult animals.
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