Caracterização do perfil do ciclo sono-vigília em ratos sob dessincronização forçada
The circadian behavior associated with the 24 hours light-dark (LD) cycle (T24) is due to a circadian clock , which in mammals is located in the hypothalamic suprachiasmatic nucleus (SCN). Under experimental conditions in which rats are espoused to a symmetric LD 22h cycle (T22) the two SCN regions...
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| Formato: | Dissertação |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/18487 |
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| Resumo: | The circadian behavior associated with the 24 hours light-dark (LD) cycle (T24) is due to
a circadian clock , which in mammals is located in the hypothalamic suprachiasmatic
nucleus (SCN). Under experimental conditions in which rats are espoused to a
symmetric LD 22h cycle (T22) the two SCN regions, ventrolateral (vl) and dorsomedial
(dm), can be functionally isolated, suggesting that each region regulates distinct
physiological and behavioral components. The vl region regulates the locomotor activity
and slow wave sleep (SWS) rhythms, while the dm region assures the body
temperature and paradoxical sleep (PS) rhythms regulation. This research aimed to
deepen the knowledge on the functional properties of circadian rhythmicity, specifically
about the internal desynchronization process, and its consequences to locomotor
activity and body temperature rhythms as well as to the sleep-wake cycle pattern in
rats. We applied infrared motion sensors, implanted body temperature sensors and a
telemetry system to record electrocorticogram (ECoG) and electromyogram (EMG) in
two rat groups. The control group under 24h period LD cycle (T24: 12hL-12hD) to the
baseline record and the experimental group under 22h period LD cycle (T22: 11hL-
11hD), in which is known to occur the uncoupling process of the circadian locomotor
activity rhythm where the animals show two distinct locomotor activity rhythms: one
synchronized to the external LD cycle, and another expressed in free running course,
with period greater than 24h. As a result of 22h cycles, characteristic locomotor activity moment appear, that are coincidence moments (T22C) and non coincidence moments
(T22NC) which were the main focus or our study. Our results show an increase in
locomotor activity, especially in coincidence moments, and the inversion of locomotor
activity, body temperature, and sleep-wake cycle patterns in non coincidence
moments. We can also observe the increase in SWS and decrease in PS, both in
coincidence and non coincidence moments. Probably the increases in locomotor
activity as a way to promote the coupling between circadian oscillators generate an
increased homeostatic pressure and thus increase SWS, promoting the decreasing in
PS |
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