DFIS - Departamento de Fisiologia e Comportamento

URI Permanente desta comunidadehttps://repositorio.ufrn.br/handle/1/8

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Agora exibindo 1 - 5 de 5

Caminos de la neurociencia en América Latina
(2013-01) Cardenas, Fernando P.; Araujo, John Fontenele; León, Laura Andrea
Não possui resumo.
Daily anticipatory rhythms of behavior and body temperature in response to glucose availability in rats
(2012) Carneiro, Breno T. S.; Fernandes, Diego A. C.; Medeiros, Caio F. P.; Diniz, Nathália L.; Araujo, John Fontenele
When food is available recurrently at a particular time of day, several species increase their locomotion in the hours that precede food delivery, a phenomenon called food anticipatory activity (FAA). In mammals, many studies have shown that FAA is driven by a food-entrained circadian oscillator (FEO) that is distinct from the light-entrained pacemaker in the suprachiasmatic nucleus of the hypothalamus. Few studies have investigated the effect of sugar ingestion on food anticipatory rhythms and the FEO. We aimed to extend the understanding of the role of glucose on the emergence of food anticipatory rhythms by investigating whether glucose ingestion is sufficient to produce daily food anticipation, reflected by motor activity and core body temperature rhythms. Under a 12 h/12 h light/dark cycle, chow-deprived rats had glucose solution available between Zeitgeber Time (ZT) 6 and ZT 9 for 10 days (glucose restriction group), whereas control animals had chow available within the same time window (chow restriction group). Animals in both groups exhibited anticipatory motor activity and body temperature around the fourth day of the scheduled food restriction. Glucose-fed rats ingested ~15 kcal on the days immediately before FAA emergence and reached an intake of ~20 kcal/day, whereas chow-fed rats ingested ~40 kcal/day. The glucose restriction group exhibited a pattern of food anticipation (activity and temperature) that was extremely similar to that observed in the chow restriction group. We conclude that glucose ingestion is a sufficient temporal cue to produce recurrent food anticipation, reflected by activity and temperature rhythms, in rats.
A fresh look at the use of nonparametric analysis in actimetry
(2015-04) Gonçalves, B.S.B.; Adamowicz, Taísa; Louzada, Fernando Mazzilli; Moreno, Claudia Roberta; Araujo, John Fontenele
Actimetry has been used to estimate the sleep–wake cycle instead of the rest-activity rhythm. Although algorithms for assessing sleep from actimetry data exist, it is useful to analyze the rest-activity rhythm using nonparametric methods. This would then allow rest-activity rhythm stability, fragmentation and amplitude to be quantified. In addition, sleep and wakefulness efficiency can be quantified separately. These variables have been used in studies analyzing the effect of age, diseases and their respective treatments on human circadian rhythmicity. In this study, we carried out a comprehensive analysis of the main results from published articles and devised a functional model of interaction among the several components involved in generating the sleep–wake cycle. The nonparametric variables render it possible to infer the main characteristics of circadian rhythms, such as synchronization with a zeitgeber, and its amplitude and robustness
Latitudinal cline of chronotype
(Nature, 2017-07-14) Miguel, Mario André Leocadio; Louzada, Fernanda Mazzili; Duarte, Leandro Lourenção; Areas, Roberto Peixoto; Alam, Marilene; Freire, Marcelo Ventura; Araujo, John Fontenele; Barreto, Luiz Menna; Pedrazzoli, Mario
The rotation of the Earth around its own axis and around the sun determines the characteristics of the light/dark cycle, the most stable and ancient 24 h temporal cue for all organisms. Due to the tilt in the earth’s axis in relation to the plane of the earth’s orbit around the sun, sunlight reaches the Earth differentially depending on the latitude. The timing of circadian rhythms varies among individuals of a given population and biological and environmental factors underlie this variability. In the present study, we tested the hypothesis that latitude is associated to the regulation of circadian rhythm in humans. We have studied chronotype profiles across latitudinal cline from around 0° to 32° South in Brazil in a sample of 12,884 volunteers living in the same time zone. The analysis of the results revealed that humans are sensitive to the different sunlight signals tied to differences in latitude, resulting in a morning to evening latitudinal cline of chronotypes towards higher latitudes.
Latitudinal cline of chronotype
(2017-07-14) Miguel, Mario André Leocadio; Louzada, Fernando Mazzili; Duarte, Leandro Lourenção; Areas, Roberta Peixoto; Alam, Marilene; Freire, Marcelo Ventura; Araujo, John Fontenele; Barreto, Luiz Menna; Pedrazzoli, Mario
The rotation of the Earth around its own axis and around the sun determines the characteristics of the light/dark cycle, the most stable and ancient 24 h temporal cue for all organisms. Due to the tilt in the earth’s axis in relation to the plane of the earth’s orbit around the sun, sunlight reaches the Earth differentially depending on the latitude. The timing of circadian rhythms varies among individuals of a given population and biological and environmental factors underlie this variability. In the present study, we tested the hypothesis that latitude is associated to the regulation of circadian rhythm in humans. We have studied chronotype profiles across latitudinal cline from around 0° to 32° South in Brazil in a sample of 12,884 volunteers living in the same time zone. The analysis of the results revealed that humans are sensitive to the different sunlight signals tied to differences in latitude, resulting in a morning to evening latitudinal cline of chronotypes towards higher latitudes

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