Dissertações em Neurociências e Biologia Celular (Mestrado) - PPGNBC/ICB

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2375

O Mestrado Acadêmico pertence ao Programa de Pós-Graduação em Neurociências e Biologia Celular (PPGNBC) do Instituto de Ciências Biológicas (ICB) da Universidade Federal do Pará (UFPA).

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Caracterização morfológica de astrócitos da formação hipocampal de maçaricos da espécie calidris pusilla durante a migração e em período de invernada
(Universidade Federal do Pará, 2017-04-12) PAULO, Dario Carvalho; DINIZ, Cristovam Guerreiro; http://lattes.cnpq.br/1025250990755299; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
The semipalmated sandpiper Calidris pusilla (C. pusilla) is a long-distance migrant shorebird that leaves every year, its breeding habitats in the southern tundra in Canada and Alaska, escaping from winter, towards the coastal line in South America. Before they cross the Atlantic Ocean, they stopover Bay of Fundy on the Atlantic coast of North America, where they increase triglycerides in adipose tissue, to attend the vigorous energetic demands of the 5,300-kilometer non-stop flight over the ocean. Because bioenergetic and redox activity of astrocytes would be under intense demand to sustain neuronal activity and survival during long-distance transatlantic migration, we hypothesize that astrocytes morphological changes may become readily visible in the wintering birds. To test this hypothesis, GFAP immunolabeled astrocytes were selected from sections of the hippocampal formation, an area that has been proposed to play a central role in the integration of multisensory spatial information for navigation. We quantified and compared hippocampal three-dimensional morphological features of astrocytes of adult migrating, captured on the Bay of Fundy, Canada, with hippocampal astrocytes from birds captured in the coastal region of Bragança, Brazil, during the wintering period. To select astrocytes for microscopic 3D reconstructions we used a random and systematic unbiased sampling approach. Using hierarchical cluster and discriminant analysis of 3D morphometric features to classify astrocytes, we found two morphological phenotypes (designated types I and II) both in migrating and wintering individuals. Although in remarkable different extent, the morphological complexities of both types of astrocytes were reduced after long-distance non-stop flight. Indeed, birds captured in the coastal region of Bragança, Brazil, during the wintering period, showed less complex astrocytic morphology than individuals captured in the Bay of Fundy, Canada, during fall migration. Because the reduction in complexity was much more intense in type I than in type II astrocytes, we suggest that these distinct morphological phenotypes may be associated with different physiological roles during migration. Indeed, as compared to type I, most type II astrocytes did not change significantly their morphology after the long-distance flight and many of them (72.5%) revealed unequivocally connection with blood vessels, whereas type I revealed only 27.5%.
Acesso aberto (Open Access)
Cinética da infecção pelo arbovírus piry em modelo murino: a resposta do hospedeiro adulto
(Universidade Federal do Pará, 2011-09-30) SANTOS, Zaire Alves dos; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
In the present report, a member of a group of RNA South American viruses found in Brazil, that causes febrile disease in humans and encephalitis in neonate and adult murine models, was selected as a model to study encephalitis outcomes in adult albino Swiss mice. In mice housed under standard conditions with free access to water and food, we induced viral encephalitis by intranasal inoculation of Piry virus–infected brain homogenate and correlated neuropathological features. We quantified the cellular inflammatory response in the septal region using a stereologically based unbiased method with clinical signs and neuroinvasion, comparing the outcomes with those of animals inoculated with uninfected brain homogenate. Three-month-old female mice maintained in standard environment received an equal volume of Piry virus infected or normal brain homogenates into the nostrils. From the 1st to 8th days post-instillation (dpi), five subjects from the infected colony were fixed and processed to detect viral antigens and microglia. Control subjects were sacrificed in the 5th dpi and processed for the same markers. After Piry virus encephalitis induced microglial activation and neuroinvasion of glial cells and neurons mainly in the olfactory pathways early in the disease (2 – 4 dpi), but also included hippocampus, cerebellum and brain stem nuclei later on (5 - 8 dpi). The correlation of the host cellular inflammatory quantitative response in the septal area with clinical signs and neuroinvasion, revealed that the number and the morphology of microglias changed early in the disease before neuroinvasion had reached the septal region and clinical signs had appeared. Great variability in clinical symptoms intensity and survival rate were found in the outbred albino Swiss mice strain as compared with previous report in the inbred C57Bl6 strain suggesting less isogenic background. Taken together, our previous and present report dedicated to investigate Piry virus encephalitis progression in the outbred albino Swiss mice strain may open a new field of investigation of the genetics, anatomical and immune substrates of tropical sublethal arbovirus encepahlitis.
Acesso aberto (Open Access)
Encefalite viral induzida pelo vírus da dengue em camundongos suíços albinos: a resposta inflamatória do sistema nervoso central do hospedeiro neonato
(Universidade Federal do Pará, 2011-10-14) TURIEL, Maíra Catherine Pereira; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
To study the innate immune response produced specifically within the developing CNS, avoiding the influence of the immune system, employ viral infection model induced by intracerebral inoculation of dengue virus in neonatal mice. Eight newborn mice two days old of the species Mus musculus and Swiss albino variety were inoculated intracerebrally with brain homogenate infected with Flavivirus species (DENV3 genotype III). Another group of animals was used as control (uninfected) and inoculated with an equal volume of non-infectious brain homogenate and maintained under the same conditions of those infected. After 7 days after infection the mice were sacrificed and patients have had their brains processed for immunostaining of astrocytes and microglia. We quantified the glial and astrocitic immune response in the stratum lacunosum molecular (Lac Mol), radiatum (Rad) and pyramidale (Pir) of hippocampus and in the stratum molecular of dentate gyrus (DGMol) using the optical ractionator to estimate the number of microglias and astrocytes in the hippocampus of infected and control animals. Intense reactive astrocytosis and microglial activation were associated with clinical signs of meningoencephalitis in neonate subjects. Although the number of activated microglia to be higher in infected than in control subjects in the GDMol (Inf:738,95 } 83,07 vs Cont: 232,73 } 70,38; p = 0,0035), Rad (Inf: 392,49 } 44,13 vs Cont: 62,76 } 15,86; p = 0,0004) the number of total microglias (activated or not) was different only in the stratum radiatum (Inf: 6.187,49 } 291,62; Cont: 4.011,89 } 509,73;p = 0,01). On the other hand the total number of astrocytes was higher in control than in infected subjects only in the DGMol (Inf: 8.720,17 } 903,11; Cont: 13.023,13 }1.192,14; p = 0,02). Taken together the results suggest that the immune innate response in neonate mice after encephalitis induced by DENV3 genotype III is associated with a higher increase in the activated microglias than astrocytes in a regional and laminardependent fashion. The patophysiology implications of these events remain to be investigated.
Acesso aberto (Open Access)
Envelhecimento, declínio cognitivo e plasticidade astroglial em ca3
(Universidade Federal do Pará, 2011-11-18) TOKUHASHI, Tatyana Pereira; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
A few studies investigated in detail possible relationships between aging cognitive decline and hippocampal astroglial plasticity. In the present report we investigated in murine model possible relationships between performances in object recognition tests and the astrocytes laminar distribution in CA3. To do so, young (6 months old, n = 7) and old (20 months old, n= 5) C57Bl6 mice, were maintained in standard cages and assessed in object recognition hippocampal-dependent tasks. Isolated or integrated (episodic-like memory) tests were applied and revealed that object identity (What?), place (Where?) and time (When?), were impaired in old subjects, whereas in young mice only spatial memory was impaired. After behavioral tests all subjects were sacrificed and perfused with aldehyde fixatives had their brains removed and processed for glial fibrillary acid protein (GFAP) immunohistochemistry, a selective marker for astrocytes. To avoid sample bias we used the optical fractionator, a stereological method that is no affected by histological procedures. The results on behavioral isolated or integrated tests revealed that aging significantly impairs object, spatial and time recognition (two-tail t-test, p<0.05). As compared to young subjects, old mice showed laminar changes in the astrocytes distribution with proportional increase of the astrocytes number in the pyramidal layer of dorsal and ventral CA3 and a reduction in the lacunosum molecular layer of dorsal CA3. Coherently, the total number of CA3 astrocytes showed significant reorganization of its laminar distribution as a function of age with reduction of its numbers in the stratum oriens. No significant differences were detected in the mean values of laminar volumes suggesting that aging induced changes directly affected astroglial plasticity in CA3. Finally, a linear inverse correlation was found between the estimations of pyramidal cell layer astrocytes and performances in the behavioral tasks. Further direct evidences of this correlation with altered CA3 astrocytes and possible molecular mechanisms to explain aging cognitive decline remains to be investigated.
Acesso aberto (Open Access)
Estudo exploratório comparativo do declínio cognitivo senil após estimulação multissensorial e cognitiva em idosos institucionalizados e não institucionalizados
(Universidade Federal do Pará, 2014-01-21) MACEDO, Liliane Dias e Dias de; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
The objective of this study was to investigate, using selected neuropsychological tests, the duration of the beneficial effects of multisensory and cognitive stimulation program in two groups of elderly living in community or in long term care institutions. The participants were institutionalized (n = 20, 75.1 ± 6.8 years old) and non-institutionalized (n =15, 74.1 ± 3.9 years old; mean ± standard deviation), with 65 years or more with no history of traumatic brain injury, cerebrovascular accident or major depression, minimal visual acuity 20/30 as measured by the Snellen test and regular participation in the program of somato-motor and cognitive stimulation. Revaluations were conducted after completion of multisensory and cognitive intervention, in five consecutive time windows (2, 4, 6, 8 and 12 months). Both elderly groups were submitted to the following tests: Boston naming; semantic and phonological verbal fluencies, Mini Mental State Examination, Narrative Tests based on the picture “The Theft of Biscuits” and selected tests of the Montreal Battery of Evaluation of Communication, and of the Cambridge Neuropsychological Test Battery (CANTAB). CANTAB tests included Motor Screening Test; Rapid Visual Information Processing; Reaction Time; Paired Associated Learning - PAL; Spatial Working Memory - SWM, and delayed matching to sample. As compared with non-institutionalized a higher rate of cognitive decline was observed in the institutionalized elderly. These results are in line with previous report that associated the poor environmental stimuli of long-term care institutions with faster aging cognitive decline. Furthermore, the ROC analysis indicated a higher specificity, selectivity and efficiency for PAL and SWM tests of the CANTAB battery. as well as memory space for work efficiency allowing the distinction between I and NI groups at all-time windows. The results demonstrated gradual cognitive decline after ended the stimulation program in both groups, with earlier and more severe losses in institutionalized elderly than in those living in the community with their families. The duration of the beneficial effects were closely related to the nature of the workshops and therefore the scores of language tests declined more slowly. The results are of interest to the planner of public policies to recommend regular programs of somato-motor and cognitive stimulation for elderly to reduce the progression of aging cognitive decline.
Acesso aberto (Open Access)
Influências do ambiente e da idade sobre a complexidade morfológica dos astrócitos do giro denteado de camundongos suíços albinos
(Universidade Federal do Pará, 2015-05-14) FÔRO, César Augusto Raiol; SOSTHENES, Marcia Consentino Kronka; http://lattes.cnpq.br/7881527576747420; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
During our previous study (Diniz et al., 2010), mice (Mus musculus) maintained in an impoverished environment that mimicked a sedentary lifestyle from weaning generally performed worse on spatial memory tasks (the Morris water maze) and did not distinguish between old and recent or between displaced and stationary objects in episodic-like memory tests. In contrast, mice maintained in enriched cages for equal time preserved those abilities. These behavioral outcomes were associated with layer-dependent, numerical astrocytic changes. Using the same serial anatomical sections selectively immunolabeled for glial fibrillary acid protein from the previous study, we tested the hypothesis that environmental impoverishment would reduce the morphological complexity of astrocytes, and that such changes would be associated with learning and memory decline. We used three-dimensional microscopic reconstructions and unbiased systematic and random sampling approaches to select astrocytes from the polymorphic, granular, and molecular layers of the dentate gyrus. Cluster and discriminant analysis of three-dimensional astrocytic morphometric features from each layer and experimental group revealed two main morphological phenotypes. Type I astrocytes were more complex than type II; they exhibited larger tree areas, larger tree volumes, more segments, and more vertices. Integrated analysis with previous behavioral findings from the same animals revealed that the reductions in morphological complexity observed in young mice from impoverished and aged mice from enriched environments were observed in both astrocyte types in all layers of the dentate gyrus. We suggest that long-term environmental impoverishment and aging effects on astrocyte plasticity may represent at least part of the circuitry changes underlying learning and memory decline.

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