Effects of photoperiod extension on clock gene and neuropeptide RNA expression in the SCN of the Soay sheep

Dardente, H., Wyse, C. A., Lincoln, G. A., Wagner, G. C. and Hazlerigg, D. G. (2016) Effects of photoperiod extension on clock gene and neuropeptide RNA expression in the SCN of the Soay sheep. PLoS ONE, 11(7), e0159201. (doi: 10.1371/journal.pone.0159201) (PMID:27458725) (PMCID:PMC4961288)

Abstract

In mammals, changing daylength (photoperiod) is the main synchronizer of seasonal functions. The photoperiodic information is transmitted through the retino-hypothalamic tract to the suprachiasmatic nuclei (SCN), site of the master circadian clock. To investigate effects of day length change on the sheep SCN, we used in-situ hybridization to assess the daily temporal organization of expression of circadian clock genes (Per1, Per2, Bmal1 and Fbxl21) and neuropeptides (Vip, Grp and Avp) in animals acclimated to a short photoperiod (SP; 8h of light) and at 3 or 15 days following transfer to a long photoperiod (LP3, LP15, respectively; 16h of light), achieved by an acute 8-h delay of lights off. We found that waveforms of SCN gene expression conformed to those previously seen in LP acclimated animals within 3 days of transfer to LP. Mean levels of expression for Per1-2 and Fbxl21 were nearly 2-fold higher in the LP15 than in the SP group. The expression of Vip was arrhythmic and unaffected by photoperiod, while, in contrast to rodents, Grp expression was not detectable within the sheep SCN. Expression of the circadian output gene Avp cycled robustly in all photoperiod groups with no detectable change in phasing. Overall these data suggest that synchronizing effects of light on SCN circadian organisation proceed similarly in ungulates and in rodents, despite differences in neuropeptide gene expression.

• Item Type: Articles
• Additional Information: This study was supported by the Biotechnology and Biological Sciences Research Council UK grant BB/G004463/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wyse, Dr Cathy
• Authors: Dardente, H., Wyse, C. A., Lincoln, G. A., Wagner, G. C., and Hazlerigg, D. G.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• ISSN (Online): 1932-6203
• Published Online: 26 July 2016
• Copyright Holders: Copyright © 2016 Dardente et al.
• First Published: First published in PLoS ONE 11(7): e0159201
• Publisher Policy: Reproduced under a Creative Commons License