tailieunhanh - Báo cáo y học: "Variation in nocturnality and circadian activity rhythms between photoresponsive F344 and nonphotoresponsive Sprague Dawley rats"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Variation in nocturnality and circadian activity rhythms between photoresponsive F344 and nonphotoresponsive Sprague Dawley rats. | Journal of Circadian Rhythms BioMed Central Research Variation in nocturnality and circadian activity rhythms between photoresponsive F344 and nonphotoresponsive Sprague Dawley rats Cheryl D Seroka Cynthia E Johnson and Paul D Heideman Address Department of Biology College of William and Mary Williamsburg VA 23187 USA Email Cheryl D Seroka - cdseroka@ Cynthia E Johnson - cejohn@ Paul D Heideman - pdheid@ Corresponding author Open Access Published 9 September 2008 Received 28 May 2008 Journal ofCircadian Rhythms 2008 6 8 doi 1740-3391-6-8 Accepted 9 September 2008 This article is available from http content 6 1 8 2008 Seroka et al licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Background Variation in circadian rhythms and nocturnality may hypothetically be related to or independent of genetic variation in photoperiodic mediation of seasonal changes in physiology and behavior. We hypothesized that strain variation in photoperiodism between photoperiodic F344 rats and nonphotoperiodic Harlan Sprague Dawley HSD rats might be caused by underlying variation in clock function. We predicted that HSD rats would have more activity during the day or subjective day longer free-running rhythms poor entrainment to short day length and shorter duration of activity traits that have been associated with nonphotoperiodism in other laboratory rodent species relative to F344 rats. An alternative hypothesis that differences are due to variation in melatonin secretion or responses to melatonin predicts either no such differences or inconsistent combinations of differences. Methods We tested these predictions by examining activity rhythms of young male F344 and HSD rats given access to