title: Circadian urinary excretion rhythms in adrenalectomized rats.
abstract: The impact of the adrenal system on urinary rhythms was investigated in adrenalectomized (ADX) rats under various experimental conditions. During a 12:12 light-dark cycle the acrophases were shifted in ADX rats with respect to control rats. Under constant light conditions ADX rats displayed free-running rhythms, similar to those of control rats. The periods were stable in blind rats but not in rats maintained on a constant light cycle. The abrupt change in period, which occurred after approximately 8 days, suggests a stage of internal desynchronization. A 6-h delay in the administration of corticosterone to ADX rats caused a delay shift of the acrophases. A single intraperitoneal injection of corticosterone in blind free-running ADX rats caused delay or advance shifts so that we could construct phase-response curves for the various excretory rhythms. These observations indicate that the adrenals are not essential for the establishment of the urinary rhythms; however, corticosterone influences the phase setting of these rhythms. The site of action is probably the X pacemaker (controlling the body temperature rhythm), although we cannot totally exclude an additional effect on secondary (renal) oscillators.
mesh_terms: D000315:Adrenalectomy; D000450:Aldosterone / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001766:Blindness / Q000503:physiopathology; D002940:Circadian Rhythm; D003345:Corticosterone / Q000008:administration & dosage / Q000494:pharmacology; D004231:Diuresis; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000450:Aldosterone; D003345:Corticosterone