Pregnancy-induced changes in ultradian rhythms persist in circadian arrhythmic Siberian hamsters

Z Yan Wang; Erin J Cable; Irving Zucker; Brian J Prendergast

doi:10.1016/j.yhbeh.2014.04.014

Pregnancy-induced changes in ultradian rhythms persist in circadian arrhythmic Siberian hamsters

Horm Behav. 2014 Jul;66(2):228-37. doi: 10.1016/j.yhbeh.2014.04.014. Epub 2014 May 2.

Authors

Z Yan Wang¹, Erin J Cable², Irving Zucker³, Brian J Prendergast⁴

Affiliations

¹ Committee on Neurobiology, University of Chicago, Chicago, IL 60637, USA. Electronic address: zyw@uchicago.edu.
² Department of Psychology, University of Chicago, Chicago, IL 60637, USA.
³ Department of Psychology, University of California, Berkeley, CA 94720, USA; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
⁴ Committee on Neurobiology, University of Chicago, Chicago, IL 60637, USA; Department of Psychology, University of Chicago, Chicago, IL 60637, USA.

Abstract

The impact of pregnancy and lactation on ultradian rhythms (URs) and circadian rhythms (CRs) of locomotor activity was assessed in circadian rhythmic and arrhythmic Siberian hamsters maintained in a long-day photoperiod (16h light/day). Progressive decrements in CR robustness and amplitude over the course of gestation were accompanied by enhanced URs. Dark-phase UR period and amplitude increased during early gestation and complexity and robustness increased during late gestation. The persistence of pregnancy-associated enhancements of URs in circadian arrhythmic (ARR) hamsters suggests that reproductive modulation of the UR waveform is not dependent on coherent circadian organization. The increased incidence of dark-phase URs appeared more rapidly in ARR dams than entrained (ENTR) dams. Throughout gestation, the percentage of dams with dark-phase URs was significantly greater in the ARR group. Gestational increases in UR complexity and robustness emerged earlier and were greater in ARR than ENTR dams. The attenuation of CRs during lactation is correlated with increased expression of URs. Relaxation of circadian control of the dam's behavior may increase fitness by permitting more efficient interactions with circadian arrhythmic pups.

Keywords: Arrhythmia; Biological rhythms; Lactation; Maternal behavior; Reproduction; Suprachiasmatic nucleus.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Activity Cycles / physiology*
Animals
Circadian Rhythm / physiology*
Cricetinae
Darkness
Female
Light
Motor Activity / physiology
Phenotype
Phodopus
Pregnancy
Sexual Behavior, Animal

Grants and funding

R01 AI067406/AI/NIAID NIH HHS/United States