title: Circadian and ultradian glucocorticoid rhythmicity: Implications for the effects of glucocorticoids on neural stem cells and adult hippocampal neurogenesis.
abstract: Psychosocial stress, and within the neuroendocrine reaction to stress specifically the glucocorticoid hormones, are well-characterized inhibitors of neural stem/progenitor cell proliferation in the adult hippocampus, resulting in a marked reduction in the production of new neurons in this brain area relevant for learning and memory. However, the mechanisms by which stress, and particularly glucocorticoids, inhibit neural stem/progenitor cell proliferation remain unclear and under debate. Here we review the literature on the topic and discuss the evidence for direct and indirect effects of glucocorticoids on neural stem/progenitor cell proliferation and adult neurogenesis. Further, we discuss the hypothesis that glucocorticoid rhythmicity and oscillations originating from the activity of the hypothalamus-pituitary-adrenal axis, may be crucial for the regulation of neural stem/progenitor cells in the hippocampus, as well as the implications of this hypothesis for pathophysiological conditions in which glucocorticoid oscillations are affected.
authors.affiliation: Neuroscience Program, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands. Electronic address: c.p.fitzsimons@uva.nl.
authors.forename: Carlos P
authors.initials: CP
authors.lastname: Fitzsimons
authors.affiliation: John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, United Kingdom.
authors.forename: Joe
authors.initials: J
authors.lastname: Herbert
authors.affiliation: Neuroscience Program, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands.
authors.forename: Marijn
authors.initials: M
authors.lastname: Schouten
authors.affiliation: Leiden University Medical Centre, Department of Endocrinology, Leiden, The Netherlands.
authors.forename: Onno C
authors.initials: OC
authors.lastname: Meijer
authors.affiliation: Neuroscience Program, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands. Electronic address: p.j.lucassen@uva.nl.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Lucassen
authors.affiliation: Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol, United Kingdom.
authors.forename: Stafford
authors.initials: S
authors.lastname: Lightman
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005938:Glucocorticoids / Q000378:metabolism / Q000502:physiology*; D006624:Hippocampus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D058953:Neural Stem Cells / Q000378:metabolism / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology*; D013315:Stress, Psychological / Q000378:metabolism*; D000071218:Ultradian Rhythm / Q000502:physiology*
chemical_list: D005938:Glucocorticoids
keywords: Adult hippocampal neurogenesis; Glucocorticoid oscillations; Neural stem cells; Stress; Ultradian