Photoperiod differentially modulates photic and nonphotic phase response curves of hamsters. Am J Physiol Regul Integr Comp Physiol 2004 Mar;286(3):R539-46
Date
12/03/2003Pubmed ID
14644756DOI
10.1152/ajpregu.00456.2003Scopus ID
2-s2.0-1342309867 (requires institutional sign-in at Scopus site) 46 CitationsAbstract
Circadian pacemakers respond to light pulses with phase adjustments that allow for daily synchronization to 24-h light-dark cycles. In Syrian hamsters, Mesocricetus auratus, light-induced phase shifts are larger after entrainment to short daylengths (e.g., 10 h light:14 h dark) vs. long daylengths (e.g., 14 h light:10 h dark). The present study assessed whether photoperiodic modulation of phase resetting magnitude extends to nonphotic perturbations of the circadian rhythm and, if so, whether the relationship parallels that of photic responses. Male Syrian hamsters, entrained for 31 days to either short or long daylengths, were transferred to novel wheel running cages for 2 h at times spanning the entire circadian cycle. Phase shifts induced by this stimulus varied with the circadian time of exposure, but the amplitude of the resulting phase response curve was not markedly influenced by photoperiod. Previously reported photoperiodic effects on photic phase resetting were verified under the current paradigm using 15-min light pulses. Photoperiodic modulation of phase resetting magnitude is input specific and may reflect alterations in the transmission of photic stimuli.
Author List
Evans JA, Elliott JA, Gorman MRAuthor
Jennifer A. Evans PhD Assistant Professor in the Biomedical Sciences department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
AnimalsCircadian Rhythm
Cricetinae
Male
Mesocricetus
Motor Activity
Orchiectomy
Photic Stimulation
Photoperiod
Testosterone
