Circadian rhythms in zebrafish (Danio rerio) behaviour and the sources of their variability

Abstract

Over recent decades, changes in zebrafish (Danio rerio) behaviour have become popular quantitative indicators in biomedical studies. The circadian rhythms of behavioural processes in zebrafish are known to enable effective utilization of energy and resources, therefore attracting interest in zebrafish as a research model. This review covers a variety of circadian behaviours in this species, including diurnal rhythms of spawning, feeding, locomotor activity, shoaling, light/dark preference, and vertical position preference. Changes in circadian activity during zebrafish ontogeny are reviewed, including ageing-related alterations and chemically induced variations in rhythmicity patterns. Both exogenous and endogenous sources of inter-individual variability in zebrafish circadian behaviour are detailed. Additionally, we focus on different environmental factors with the potential to entrain circadian processes in zebrafish. This review describes two principal ways whereby diurnal behavioural rhythms can be entrained: (i) modulation of organismal physiological state, which can have masking or enhancing effects on behavioural endpoints related to endogenous circadian rhythms, and (ii) modulation of period and amplitude of the endogenous circadian rhythm due to competitive relationships between the primary and secondary zeitgebers. In addition, different peripheral oscillators in zebrafish can be entrained by diverse zeitgebers. This complicated orchestra of divergent influences may cause variability in zebrafish circadian behaviours, which should be given attention when planning behavioural studies.

Magnetic fluctuations affect circadian patterns of locomotor activity in zebrafish

“…The circadian rhythms in the dynamics of the studied parameters at the first stage of the experiment correspond to the known patterns of zebrafish circadian behavior governed by daily changes in illumination [26]. Additional peaks at 15.84 h on the periodograms for the wall preference index and angular velocity are associated with a well-documented phenomenon of visual-motor response in zebrafish [37].…”

“…The lack of a centralized pacemaker subjugating all other oscillators in zebrafish could increase the chance to detect changes in circadian rhythms caused by a magnetic influence. The influence of different light and magnetic exposures on zebrafish rhythms was analyzed through locomotor activity and several related endpoints known as precise indicators of circadian rhythmicity in this species [26].…”

Age-dependent expression changes of circadian system-related genes reveal a potentially conserved link to aging

“…Therefore, the age-related changes in the CR regulation might have a positive effect on the longer lifespan of the old-age individuals. This explanation remains speculative, requiring further investigations of the CR in N. furzeri , similar to studies available in D. rerio [ 5 , 48 ].…”

Gonadotropin Releasing Hormone (GnRH) Triggers Neurogenesis in the Hypothalamus of Adult Zebrafish

“…Hypothalamic neurogenesis, as well as other age-related phenotypes, can be restored by injection of GnRH [ 28 , 64 ]. Our findings that GnRH can increase proliferation of cells in the POA of adult animals, coupled with the development of zebrafish as a model for neurodegeneration in the context of aging [ 65 ], and aging-related alterations in patterns of sleep and rhythmicity patterns [ 66 ], open the door for investigations into how inhibition of inflammation and/or GnRH therapy could revert symptoms of aging-related diseases.…”