Cargando…

Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters

Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for indu...

Descripción completa

Detalles Bibliográficos
Autores principales: Prendergast, Brian J., Zucker, Irving
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407235/
https://www.ncbi.nlm.nih.gov/pubmed/22848579
http://dx.doi.org/10.1371/journal.pone.0041723
_version_ 1782239317397078016
author Prendergast, Brian J.
Zucker, Irving
author_facet Prendergast, Brian J.
Zucker, Irving
author_sort Prendergast, Brian J.
collection PubMed
description Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L) and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR) robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs) were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ’), amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders), τ’ of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L–13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters.
format Online
Article
Text
id pubmed-3407235
institution National Center for Biotechnology Information
language English
publishDate 2012
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-34072352012-07-30 Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters Prendergast, Brian J. Zucker, Irving PLoS One Research Article Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L) and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR) robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs) were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ’), amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders), τ’ of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L–13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters. Public Library of Science 2012-07-27 /pmc/articles/PMC3407235/ /pubmed/22848579 http://dx.doi.org/10.1371/journal.pone.0041723 Text en © 2012 Prendergast, Zucker http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Prendergast, Brian J.
Zucker, Irving
Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters
title Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters
title_full Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters
title_fullStr Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters
title_full_unstemmed Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters
title_short Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters
title_sort photoperiodic influences on ultradian rhythms of male siberian hamsters
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407235/
https://www.ncbi.nlm.nih.gov/pubmed/22848579
http://dx.doi.org/10.1371/journal.pone.0041723
work_keys_str_mv AT prendergastbrianj photoperiodicinfluencesonultradianrhythmsofmalesiberianhamsters
AT zuckerirving photoperiodicinfluencesonultradianrhythmsofmalesiberianhamsters