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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caracteriza??o do ritmo circadiano de atividade e repouso em saguis idosos (Callithrix Jacchus) / Characterization of circadian activity rhythm in aged marmosets (Callithrix jacchus)

Gon?alves, Fabiana Barbosa 01 September 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-06T19:40:24Z No. of bitstreams: 1 FabianaBarbosaGoncalves_TESE.pdf: 11151723 bytes, checksum: 742da6ff3b3d6f8fc06c1cfe8e1ba231 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-07T17:59:55Z (GMT) No. of bitstreams: 1 FabianaBarbosaGoncalves_TESE.pdf: 11151723 bytes, checksum: 742da6ff3b3d6f8fc06c1cfe8e1ba231 (MD5) / Made available in DSpace on 2016-07-07T17:59:55Z (GMT). No. of bitstreams: 1 FabianaBarbosaGoncalves_TESE.pdf: 11151723 bytes, checksum: 742da6ff3b3d6f8fc06c1cfe8e1ba231 (MD5) Previous issue date: 2015-09-01 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A idade avan?ada pode se tornar um fator limitante para a manuten??o da ritmicidade dos organismos, podendo reduzir a capacidade de gera??o e de sincroniza??o dos ritmos biol?gicos. Neste estudo, foi avaliada a influ?ncia do envelhecimento na express?o da periodicidade end?gena e sincroniza??o (f?tica e social) do ritmo circadiano de atividade (RCA) em um primata diurno, o sagui (Callithrix jacchus). Esse estudo teve dois enfoques: um com abordagem longitudinal, realizado com um sagui macho nas fases adulta (3 anos) e idosa (9 anos) (estudo 1), e o segundo com uma abordagem transversal, com 6 idosos (?: 9,7 ? 2,0 anos) e 11 adultos (?: 4,2 ? 0,8 anos) (estudo 2). A avalia??o da sincroniza??o f?tica envolveu etapas de CE (natural e artificial). No estudo 1, o animal foi submetido ?s seguintes etapas: CE (12:12 ~350:~2 lux), CC (~350 lux) e ressincroniza??o ao CE. No estudo 2, os animais foram avaliados inicialmente em CE natural, e posteriormente na mesma sequ?ncia de condi??es do estudo 1. Durante a etapa de CC no estudo 2, as vocaliza??es di?rias de coespec?ficos mantidos em CE natural na parte externa da col?nia foram consideradas como pista temporal para a sincroniza??o social. O registro da atividade foi realizado automaticamente em intervalos de 5 minutos atrav?s de sensor infravermelho e act?metro, nos estudos 1 e 2, respectivamente. De forma geral, os idosos apresentaram um padr?o de atividade mais fragmentado (> IV, < H e > PSD, ANOVA; p < 0,05), menores n?veis de atividade (ANOVA; p < 0,05) e menor dura??o da fase ativa (ANOVA; p < 0,05) nas condi??es de CE, quando comparados aos adultos. Em CE natural, os idosos apresentaram atraso de fase pronunciado para in?cio e fim da ativa (ANOVA; p < 0,05), enquanto que os adultos apresentaram fase ativa mais ajustada ? fase de claro. Sob CE artificial, houve avan?o de fase e maior ajuste dos hor?rios de in?cio e fim da atividade em rela??o ao CE nos idosos (ANOVA; p < 0,05). Em CC, houve correla??o positiva entre a idade e o per?odo end?geno (t) nos primeiros 20 dias (Correla??o de Pearson; p < 0,05), com o prolongamento do per?odo mantido em dois animais idosos. Nesta condi??o, a maioria dos adultos apresentou ritmo de atividade em livre-curso com t < 24 h nos primeiros 30 dias e posteriormente, coordena??o relativa mediada por pistas auditivas. No estudo 2, a an?lise cross-correlation entre os perfis de atividade dos animais em CC com os animais controle mantidos sob o CE natural, revelou que houve uma menor sincronia social em idosos. Com a resubmiss?o ao CE, a velocidade de ressincroniza??o foi mais lenta nos idosos (teste t; p < 0,05), e para um dos animais idosos houve a perda da capacidade de ressincroniza??o. De acordo com o conjunto de dados, sugere-se que o envelhecimento em saguis pode estar associado ?: 1) menor amplitude e maior fragmenta??o da atividade, acompanhadas de atraso de fase com prolongamento do t, em fun??o de mudan?as na capta??o de pistas f?ticas, na gera??o e na express?o comportamental do RCA; 2) menor capacidade de sincroniza??o f?tica do ritmo de atividade, que pode se tornar mais robusta em condi??es de ilumina??o artificial, possivelmente pelas maiores intensidades luminosas no in?cio da fase ativa devido ?s transi??es abruptas entre as fases de claro e escuro; e 3) menor capacidade de sincroniza??o n?o-f?tica por pistas auditivas de coespec?ficos, possivelmente por redu??o na capta??o sensorial e na resposta dos osciladores circadianos ?s pistas auditivas, podendo tornar o sagui idoso mais vulner?vel e menos adapt?vel ao ambiente, pois estas pistas sociais podem atuar como um importante fator coadjuvante para a sincroniza??o f?tica. / Advanced age may become a limiting factor for the maintenance of rhythms in organisms, reducing the capacity of generation and synchronization of biological rhythms. In this study, the influence of aging on the expression of endogenous periodicity and synchronization (photic and social) of the circadian activity rhythm (CAR) was evaluated in a diurnal primate, the marmoset (Callithrix jacchus). This study had two approaches: one with longitudinal design, performed with a male marmoset in two different phases: adult (three years) and older (9 y.o.) (study 1) and the second, a transversal approach, with 6 old (?: 9.7 ? 2.0 y.o.) and 11 adults animals (?: 4.2 ? 0.8 y.o.) (study 2). The evaluation of the photic synchronization involved two conditions in LD (natural and artificial illuminations). In study 1, the animal was subjected to the following stages: LD (12:12 ~ 350: ~ 2 lx), LL (~ 350 lx) and LD resynchronization. In the second study, the animals were initially evaluated in natural LD, and then the same sequence stages of study 1. During the LL stage in study 2, the vocalizations of conspecifics kept in natural LD on the outside of the colony were considered temporal cue to the social synchronization. The record of the activity was performed automatically at intervals of five minutes through infrared sensor and actimeters, in studies 1 and 2, respectively. In general, the aged showed a more fragmented activity pattern (> IV < H and > PSD, ANOVA, p < 0.05), lower levels of activity (ANOVA, p < 0.05) and shorter duration of active phase (ANOVA, p < 0.05) in LD conditions, when compared to adults. In natural LD, the aged presented phase delay pronounced for onset and offset of active phase (ANOVA, p < 0.05), while the adults had the active phase more adjusted to light phase. Under artificial LD, there was phase advance and greater adjustment of onset and offset of activity in relation to the LD in the aged (ANOVA, p < 0.05). In LL, there was a positive correlation between age and the endogenous period (?) in the first 20 days (Spearman correlation, p < 0.05), with prolonged ? held in two aged animals. In this condition, most adults showed free-running period of the circadian activity rhythm with ? < 24 h for the first 30 days and later on relative coordination mediated by auditory cues. In study 2, the cross-correlation analysis between the activity profiles of the animals in LL with control animals kept under natural LD, found that there was less social synchronization in the aged. With the resubmission to the LD, the resynchronization rate was slower in the aged (t-test; p < 0.05) and in just one aged animal there was a loss of resynchronization capability. According to the data set, it is suggested that the aging in marmosets may be related to: 1) lower amplitude and greater fragmentation of the activity, accompanied to phase delay with extension of period, caused by changes in a photic input, in the generation and behavioral expression of the CAR; 2) lower capacity of the circadian activity rhythm to photic synchronization, that can become more robust in artificial lighting conditions, possibly due to the higher light intensities at the beginning of the active phase due to the abrupt transitions between the light and dark phases; and 3) smaller capacity of non-photic synchronization for auditory cues from conspecifics, possibly due to reducing sensory inputs and responsiveness of the circadian oscillators to auditory cues, what can make the aged marmoset most vulnerable, as these social cues may act as an important supporting factor for the photic synchronization.

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