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: Failure to respond to endogenous or exogenous melatonin may cause . | Journal of Circadian Rhythms BioMed Central Research Open Access Failure to respond to endogenous or exogenous melatonin may cause nonphotoresponsiveness in Harlan Sprague Dawley rats Matthew Rocco Price Julie Anita Marie Kruse M Eric Galvez Annaka M Lorincz Mauricio Avigdor and Paul D Heideman Address Department of Biology College of William and Mary Williamsburg VA 23187 USA Email Matthew Rocco Price - mrpric@ Julie Anita Marie Kruse - julie@ M Eric Galvez - Annaka M Lorincz - annakab@ Mauricio Avigdor - mavigdor@ Paul D Heideman - pdheid@ Corresponding author Published 14 September 2005 Received 08 July 2005 ._- .n J- .IA I ioz - IAccepted 14 September 2005 Journal of Circadian Rhythms 2005 3 12 doi 1740-3391-3-12 This article is available from http content 3 1 12 2005 Price 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 Responsiveness to changing photoperiods from summer to winter seasons is an important but variable physiological trait in most temperate-zone mammals. Variation may be due to disorders of melatonin secretion or excretion or to differences in physiological responses to similar patterns of melatonin secretion and excretion. One potential cause of nonphotoresponsiveness is a failure to secrete or metabolize melatonin in a pattern that reflects photoperiod length. Methods This study was performed to test whether a strongly photoresponsive rat strain F344 and strongly nonphotoresponsive rat strain HSD have similar circadian urinary excretion profiles of the major metabolite of melatonin 6-sulfatoxymelatonin aMT6s in long-day L D 16 8 and short-day L D 8 16 photoperiods. The .
