Ultradian corticosterone secretion is maintained in the absence of circadian cues

Eleanor J. Waite, Mervyn Mckenna, Yvonne Kershaw, Jamie J. Walker, Kwangwook Cho, Hugh D. Piggins, Stafford L. Lightman

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Plasma levels of corticosterone exhibit both circadian and ultradian rhythms. The circadian component of these rhythms is regulated by the suprachiasmatic nucleus (SCN). Our studies investigate the importance of the SCN in regulating ultradian rhythmicity. Two approaches were used to dissociate the hypothalamic-pituitary-adrenal (HPA) axis from normal circadian input in rats: (i) exposure to a constant light (LL) environment and (ii) electrolytic lesioning of the SCN. Blood was sampled using an automated sampling system. As expected, both treatments resulted in a loss of the circadian pattern of corticosterone secretion. Ultradian pulsatile secretion of corticosterone however, was maintained across the 24h in all animals. Furthermore, the loss of SCN input revealed an underlying relationship between locomotor and HPA activity. In control (LD) rats there was no clear correlation between ultradian locomotor activity and hormone secretion, whereas, in LL rats, episodes of ultradian activity were consistently followed by periods of increased pulsatile hormone secretion. These data clearly demonstrate that the ultradian rhythm of corticosterone secretion is generated through a mechanism independent of the SCN input, supporting recent evidence for a sub-hypothalamic pulse generator. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.
    Original languageEnglish
    Pages (from-to)3142-3150
    Number of pages8
    JournalEuropean Journal of Neuroscience
    Volume36
    Issue number8
    DOIs
    Publication statusPublished - Oct 2012

    Keywords

    • HPA axis
    • Rat
    • Suprachiasmatic nucleus
    • Ultradian rhythm

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