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Enhancement And Suppression Of Ultradian And Circadian Rhythms Across The Female Hamster Reproductive Cycle, Brian J. Prendergast, Annaliese K. Beery, Matthew J. Paul, Irving Zucker

Neuroscience: Faculty Publications

The impact of ovarian hormones on hamster ultradian rhythms (URs) is unknown. We concurrently monitored URs and circadian rhythms (CRs) of home cage locomotor activity during the estrous cycle, pregnancy, and lactation of Syrian hamsters. URs with a mean period of 4–5 h were evident during the dark phase in more than 90% of females on days 1 and 2 of the estrous cycle but were significantly less prevalent on cycle days 3 and 4. The period of the UR did not vary as a function of estrous cycle stage, but at all stages, the UR period was longer in …