Circannual fluctuations of the serum cortisol in the European ground squirrel, Citellus citellus L |
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Authors: | T M Shivatcheva V K Ankov A I Hadjioloff |
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Affiliation: | Institute of Cell Biology and Morphology, Bulgarian Academy of Sciences, Sofia. |
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Abstract: | 1. Serum cortisol levels were measured throughout an annual cycle in male European ground squirrels, Citellus citellus L. 2. A circannual rhythm of these levels in euthermic animals was found: the highest being in late October, November and December, the lowest in May, early October and March. 3. The levels varied in the hibernating period as well: strongly reduced during the first part (October-December) and significantly elevated in the second one (January-March). 4. A significant elevation of the cortisol levels was marked 18-20 hr after full arousal from hibernation in October. |
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