title: Resynchronization patterns for urinary rhythms in rats after light-dark shifts.
abstract: Diurnal urinary rhythms during a fixed 12:12 light-dark cycle were studied in male and female rats. After a control period of 9 days the light-dark cycle was shifted either +6 or -6 h by delaying or advancing the light period, respectively. Subsequently the resynchronization process was studied for 19-21 days. In both male and female rats an asymmetry effect was present: resynchronization was more rapid after a -6-h shift than after a +6-h shift. However, female rats exhibited a rate of resynchronization slower than male rats. During the process of resynchronization a state of transient internal dissociation was found for all urinary constituents. These results probably point to different control systems rather than to different circadian pacemakers. Further analysis of the role of sex steroid hormones is required in view of the sex variations reported.
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D003624:Darkness; D005260:Female; D008027:Light; D008297:Male; D010710:Phosphates / Q000652:urine; D011188:Potassium / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains / Q000652:urine*; D012964:Sodium / Q000652:urine; D014508:Urea / Q000652:urine
chemical_list: D010710:Phosphates; D014508:Urea; D012964:Sodium; D003404:Creatinine; D011188:Potassium