Navegando por Assunto "Rede perineuronal"

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Acuidade visual e matriz extracelular no córtex visual primário: alterações associadas à privação monocular precoce e ao enriquecimento ambiental
(Universidade Federal do Pará, 2012-11-08) SILVA, Nonata Lucia Trévia da; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286; DINIZ JUNIOR, José Antônio Picanço; http://lattes.cnpq.br/3850460442622655
The aim of the present study is to analyze the influence of enriched environment on the visual acuity and on the distribution of perineuronal nets (PNNs) in the primary visual cortex of albino mice that underwent monocular deprivation during the critical period of postnatal development. Mice at 10th postnatal day, were monocular deprived through right eye-lid sutured (M, n = 16) and the control group animals were not submitted to any cirurgical procedures (B, n = 16). After weaning, on postnatal day 21, animals were subdivided in: standard environment (AP) and enriched environment (AE), constituting the following groups: M.AP, M.AE, B.AP and B.AE. After 3 months, animals were submitted to grating visual acuity tests, perfused and coronal sections of their brains processed for Wisteria floribunda agglutinin to posterior stereological quantification through optical fractionator method. B.AP animals present visual acuity of 0.48 cycles/degree, while those raised in enriched environment (B.AE) present a better performance at visual test, reaching 0.996 cycles/degree. Animals with monocular deprivation had significantly lower visual acuity (M.AP 0.18 cycles/degree; M.AE 0.4 cycles/degree). Stereological quantifications revealed that enriched environment increases type 1 and the total number of perineuronal nets at supragranular and granular layers in both hemispheres of deprived animals (ANOVA, two-ways, p < 0.05) and this difference at granular layer is due to an increase of perineuronal nets mainly at the right hemisphere (ipsilateral to the monocular deprivation). At infragranular layer, M.AE animals presented an increase only at the number of type 1 PNNs in both hemispheres.
Acesso aberto (Open Access)
Efeito do ambiente sobre o período crítico de plasticidade do córtex pré-frontal de ratos
(Universidade Federal do Pará, 2012-11-19) FOLHA, Otavio Augusto de Araujo Costa; BAHIA, Carlomagno Pacheco; http://lattes.cnpq.br/0910507988777644; PEREIRA JÚNIOR, Antônio; http://lattes.cnpq.br/1402289786010170
The critical period of plasticity is a period of postnatal brain development in which neural circuits are most susceptible to environmental influence. The critical period of plasticity of the human prefrontal cortex, which is responsible for executive functions, extends from birth to the end of adolescence and early adulthood. The critical period is defined, among other factors, by the maturation of perineuronal nets, a specialized structure of the extracellular matrix, which surrounds cell bodies and proximal dendrites of inhibitory interneurons. The aim of the present work was to ascertain the effects of environmental, through different adolescence phases, on the morphofunctional structure of the prefrontal cortex of rats and the spatial and temporal distribution of perineuronal nets. Executive functions were also evaluated by testing working memory capacity and behavioral inhibition. We observed that the chronic exposure to unpredictable stressors cause changes the critical period of plasticity in the prefrontal cortex and thereby influence the maturation of executive functions. We also observed that chronic stress induces changes in the spatial and temporal expression of perineuronal nets in the prefrontal cortex. More specifically, it induces the early maturation of these structures in adolescent rat brain. These results indicate the vulnerability of the adolescent brain to the negative effects of chronic stressors present in the environment.