Thermoregulation in the cold changes depending on the time of day and feeding condition: physiological and anatomical analyses of involved circadian mechanisms

K. Tokizawa, Y. Uchida, Kei Nagashima

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    Abstract

    The circadian rhythm of body temperature (Tb) is a well-known phenomenon. However, it is unknown how the circadian system including the suprachiasmatic nucleus (SCN) and clock genes affects thermoregulation. Food deprivation in mice induces a greater reduction of Tb particularly in the light phase. We examined the role of Clock, one of key clock genes and the SCN during induced hypothermia. At 20 °C with fasting, mice increased their metabolic heat production in the dark phase and maintained Tb, whereas in the light phase, heat production was less, resulting in hypothermia. Under these conditions, neuronal activity in the SCN, assessed by cFos expression, increased only in the light phase. However, such differences in thermoregulatory and neural responses between the phases in Clock mutant mice were less marked. The neural network between the SCN and paraventricular nucleus appeared to be important in hypothermia. These findings suggest that the circadian system per se is influenced by both the feeding condition and environmental temperature and that it modulates thermoregulation.

    Original languageEnglish
    Pages (from-to)1377-1386
    Number of pages10
    JournalNeuroscience
    Volume164
    Issue number3
    DOIs
    Publication statusPublished - 2009 Dec 15

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    Keywords

    • body temperature
    • clock
    • cooling
    • fasting
    • hypothermia
    • suprachiasmatic nucleus

    ASJC Scopus subject areas

    • Neuroscience(all)

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