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dc.contributor.authorTavolaro, F.M.*
dc.contributor.authorThomson, L.M.*
dc.contributor.authorRoss, A.W.*
dc.contributor.authorMorgan, P.J.*
dc.contributor.authorHelfer, Gisela*
dc.date.accessioned2016-11-29T10:14:43Z
dc.date.available2016-11-29T10:14:43Z
dc.date.issued2015-02
dc.identifier.citationTavolaro FM, Thomson LM, Ross AW, Morgan PJ and Helfer G (2015) Photoperiodic effects on seasonal physiology, reproductive status and hypothalamic gene expression in young male F344 rats. Journal of Neuroendocrinology. 27(2): 79-87.en_US
dc.identifier.urihttp://hdl.handle.net/10454/10842
dc.descriptionyesen_US
dc.description.abstractSeasonal or photoperiodically sensitive animals respond to altered day length with changes in physiology (growth, food intake and reproductive status) and behaviour to adapt to predictable yearly changes in the climate. Typically, different species of hamsters, voles and sheep are the most studied animal models of photoperiodism. Although laboratory rats are generally considered nonphotoperiodic, one rat strain, the inbred Fischer 344 (F344) rat, has been shown to be sensitive to the length of daylight exposure by changing its physiological phenotype and reproductive status according to the season. The present study aimed to better understand the nature of the photoperiodic response in the F344 rat. We examined the effects of five different photoperiods on the physiological and neuroendocrine responses. Young male F344 rats were held under light schedules ranging from 8 h of light/day to 16 h of light/day, and then body weight, including fat and lean mass, food intake, testes weights and hypothalamic gene expression were compared. We found that rats held under photoperiods of ≥ 12 h of light/day showed increased growth and food intake relative to rats held under photoperiods of ≤ 10 h of light/day. Magnetic resonance imaging analysis confirmed that these changes were mainly the result of a change in lean body mass. The same pattern was evident for reproductive status, with higher paired testes weight in photoperiods of ≥ 12 h of light/day. Accompanying the changes in physiological status were major changes in hypothalamic thyroid hormone (Dio2 and Dio3), retinoic acid (Crabp1 and Stra6) and Wnt/b-Catenin signalling genes (sFrp2 and Mfrp). Our data demonstrate that a photoperiod schedule of 12 h of light/day is interpreted as a stimulatory photoperiod by the neuroendocrine system of young male F344 rats.en_US
dc.language.isoenen_US
dc.relation.isreferencedbyhttp://dx.doi.org/10.1111/jne.12241en_US
dc.rights© 2015 The Authors. Journal of Neuroendocrinology published by John Wiley & Sons Ltd on behalf of British Society for Neuroendocrinology. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.en_US
dc.subjectPhotoperiod; F344 rat; Body weight; Reproduction; Hypothalamic gene expressionen_US
dc.titlePhotoperiodic Effects on Seasonal Physiology, Reproductive Status and Hypothalamic Gene Expression in Young Male F344 Ratsen_US
dc.status.refereedyesen_US
dc.date.Accepted2014-11-28
dc.date.application2015-01-26
dc.typeArticleen_US
dc.type.versionPublished versionen_US
refterms.dateFOA2018-07-27T01:52:32Z


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