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Seasonal Variations in Circadian Rhythms Persist in Gonadectomized Golden-Mantled Ground SquirrelsDepartments of Psychology and Integrative Biology, University of California, Berkeley, CA 94720
Departments of Psychology and Integrative Biology, University of California, Berkeley, CA 94720 Circadian wheel-running activity was monitored in intact and gonadectomized female and male golden-mantled ground squirrels maintained in a 14L:10D photoperiod at 21 °C. Marked advances in phase angle of activity onset and increases in the duration of the daily active phase occurred each year in intact animals coincident with the phase of reproductive activity. Surprisingly, long-term gonadectomized squirrels of both sexes manifested similar seasonal changes in the circadian system. Seasonal circadian variations in locomotor activity are generated by a circannual clock independent from and not influenced by concurrent changes in secretion of gonadal hormones.
Key Words: circannual circadian locomotor activity body mass gonadal hormones ground squirrels
Journal of Biological Rhythms, Vol. 10, No. 3,
188-195 (1995) This article has been cited by other articles:
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