ADOLESCENT CIRCADIAN TIMEKEEPING IN TWO RODENT MODELS, RATTUS NORVEGICUS AND OCTODON DEGUS

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Event Abstract Back to Event ADOLESCENT CIRCADIAN TIMEKEEPING IN TWO RODENT MODELS, RATTUS NORVEGICUS AND OCTODON DEGUS Megan H. Hagenauer1, 2, 3* and Theresa M. Lee2 1 University of Michigan, Molecular Behavioral Neuroscience Institute, United States 2 University of Michigan, Psychology Department, United States 3 University of Michigan, Pediatric Endocrinology, United States Despite overwhelming evidence that the circadian timekeeping system is sensitive to gonadal hormones during perinatal development and adulthood, there has been a noticeable lack of research focusing on circadian rhythms during puberty, a developmental window of intense hormonal change. We addressed this research gap using behavioral and physiological experiments in both fast developing and slow developing rodent species (Rattus norvegicus and Octodon degus). Our results indicate that both species show large changes in chronotype during puberty similar to human adolescents, exhibiting an altered timing of rest and activity. These pubertal changes are particularly robust in males, involving a switch from bimodal to unimodal activity patterns as well as a 3–5hr magnitude phase advance of daily activity rhythms. Prepubertal gonadectomy diminished these changes in both species, indicating that pubertal increases in gonadal hormones drive chronotype changes. To determine the location of hormone action within the circadian timekeeping system, we used behavioral tests to rule out the possibility that chronotype changes during puberty were due to an alteration in passive responses to rhythmic environmental stimuli, such as the laboratory light-dark cycle. Then we characterized the phasing of “clock gene” rhythms within the central circadian regulator in the suprachiasmatic nucleus, as well as in downstream “slave” oscillators in other brain regions. Surprisingly, the phasing of these rhythms remained unchanged during puberty, despite previous evidence showing a tight correlation between these rhythms and behavioral chronotype in adults. These results suggest a striking desynchrony between adolescent rest/activity patterns and the underlying circadian physiology. We discuss these findings in the context of adolescent sleep studies and explain the relevance of our results to the debate regarding teenage chronotype and high school start times. Keywords: adolescence, Chronotype, Circadian Rhythm, Period Gene, Puberty, sex difference, Suprachiasmatic Nucleus, Testosterone Conference: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011. Presentation Type: Invited Symposium Topic: Biological rhythms Citation: Hagenauer MH and Lee TM (2011). ADOLESCENT CIRCADIAN TIMEKEEPING IN TWO RODENT MODELS, RATTUS NORVEGICUS AND OCTODON DEGUS. Front. Endocrinol. Conference Abstract: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology. doi: 10.3389/conf.fendo.2011.04.00137 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Dr. Megan H Hagenauer, University of Michigan, Molecular Behavioral Neuroscience Institute, Ann Arbor, MI, 48109, United States, hagenaue@umich.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Megan H Hagenauer Theresa M Lee Google Megan H Hagenauer Theresa M Lee Google Scholar Megan H Hagenauer Theresa M Lee PubMed Megan H Hagenauer Theresa M Lee Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.