Sex differences in behavioral circadian rhythms in laboratory rodents.

Jessica A Krizo,Eric M Mintz

doi:10.3389/fendo.2014.00234

Abstract

There is a strong bias in basic research on circadian rhythms toward the use of only male animals in studies. Furthermore, of the studies that use female subjects, many use only females and do not compare results between males and females. This review focuses on behavioral aspects of circadian rhythms that differ between the sexes. Differences exist in the timing of daily onset of activity, responses to both photic and non-photic stimuli, and in changes across the lifespan. These differences may reflect biologically important traits that are ecologically relevant and impact on a variety of responses to behavioral and physiological challenges. Overall, more work needs to be done to investigate differences between males and females as well as differences that are the result of hormonal changes across the lifespan.

Highlights

There has been a longstanding bias against the use of females in basic research involving common animal models, arising out of the belief that females show higher variability in results due to the influence of hormonal cycles [1]
We look at sex differences in basic parameters of circadian rhythms and hypothesize about their underlying mechanisms and biological relevance
Sex differences in basic behavioral activity rhythms are modest in scope; this may not be the case if the system is challenged

Summary

Sex differences in behavioral circadian rhythms in laboratory rodents

Reviewed by: Jacques Epelbaum, Université Paris Descartes, France Michael Antle, University of Calgary, Canada. There is a strong bias in basic research on circadian rhythms toward the use of only male animals in studies. This review focuses on behavioral aspects of circadian rhythms that differ between the sexes. Differences exist in the timing of daily onset of activity, responses to both photic and non-photic stimuli, and in changes across the lifespan. These differences may reflect biologically important traits that are ecologically relevant and impact on a variety of responses to behavioral and physiological challenges. More work needs to be done to investigate differences between males and females as well as differences that are the result of hormonal changes across the lifespan

INTRODUCTION

Krizo and Mintz

CONCLUSION