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Implication de l'horloge circadienne dans le contrôle des pulsatilités endocrines

Abstract : The pulsatility of hormones secretion is crucial in the endocrine system, because it confers to hormones: a role and their efficiency. In this respect, the objective of my thesis was to study the involvement of the circadian clock, which controls the daily rhythms of numerous aspects of the physiology and behavior, in these endocrine pulsatilities. In the first part of my work, we studied two functions involving a neuroendocrine pulsatile activity - body growth and female reproduction-, in the knock-out mice Cry1-/-Cry2-/-, devoid of a functional circadian clock. The main results indicate, at first, that the circadian clock interferes with the GH ultradian pulsatility, and secondly, that the circadian clock is necessary for the preservation of the infradian cycles bound to the reproduction. This study shows, on one hand that, the circadian clock plays a role in mechanisms responsible for hormonal pulsatility, and on the other hand, that this circadian clock can control non-circadian rhythms. The second part of my work consisted in understanding at which level the clock may act to regulate the endocrine pulsatility. We were interested in the pituitary gland, an important gland of the endocrine system, which presents various types of pulsatility, circadian and not circadian. The pituitary gland expresses the main the clock genes and proteins according to a daily rhythm. And, although the various cells which compose the pituitary have a different endocrine rhythmic functioning, their clocks are in phase. Finally, the pituitary clock seems to integrate various signals, such as light and food. This characterization serves as a basis for new studies to understand if the pituitary clock could also coordinate the activity of the endocrine cells within the gland and so facilitate the genesis of a global pulsatility.
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https://tel.archives-ouvertes.fr/tel-00439750
Contributor : Isabelle Bur <>
Submitted on : Tuesday, December 8, 2009 - 2:59:02 PM
Last modification on : Thursday, October 29, 2020 - 6:19:06 PM
Long-term archiving on: : Thursday, June 17, 2010 - 8:33:10 PM

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Isabelle Bur. Implication de l'horloge circadienne dans le contrôle des pulsatilités endocrines. Sciences du Vivant [q-bio]. Université Montpellier II - Sciences et Techniques du Languedoc, 2009. Français. ⟨tel-00439750⟩

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