Endurance Exercise Modifies the Circadian Clock in Zebrafish (Danio rerio) Temperature Independently.
Summary of "Endurance Exercise Modifies the Circadian Clock in Zebrafish (Danio rerio) Temperature Independently."
Aim:  Several rodent and human studies revealed that physical exercise acts as a non-photic zeitgeber for the circadian clock. The intrinsic entraining mechanism is still unknown, although it was assumed that the exercise mediated increase in core temperature could be the underlying zeitgeber. Since the homeostatic control of mammalian core temperature interferes strongly with the investigation of this hypothesis, the present study used the poikilotherm zebrafish to answer this question. Methods:  Gene transcription levels of the two circadian core clock genes period1 and clock1 were quantified using realtime qPCR of whole animal zebrafish larvae. Results:  Long term endurance exercise of zebrafish larvae aged 9 to 15 days post fertilization (dpf) or 21 to 32 dpf at a constant water temperature of 25°C caused significantly altered transcription levels of the circadian genes period1 and clock1. Cosinor analysis of diurnal transcription profiles obtained after 3 days of swim training revealed significant differences regarding acrophase, mesor and amplitude of period1, resulting in a phase delay of the gene oscillation. After termination of the exercise bout, at 15 dpf, oscillation amplitudes of both circadian genes were significantly reduced. Conclusion:  The results showed that physical exercise is able to affect the transcription of circadian genes in developing zebrafish larvae. Considering the poikilothermy of zebrafish, an exercise mediated change in body core temperature could be excluded as the underlying intrinsic zeitgeber. However, the day active zebrafish arises as a useful model to address the synchronizing effect of exercise on the circadian clock.
Affiliation
Institut für Zoologie, Universität Innsbruck, Technikerstr.25, Austria.
Journal Details
This article was published in the following journal.
Name: Acta physiologica (Oxford, England)
ISSN: 1748-1716
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22044585
- DOI: http://dx.doi.org/10.1111/j.1748-1716.2011.02382.x
Medical and Biotech [MESH] Definitions
Period Circadian Proteins
Circadian rhythm signaling proteins that influence circadian clock by interacting with other circadian regulatory proteins and transporting them into the CELL NUCLEUS.
Exercise Tolerance
The exercise capacity of an individual as measured by endurance (maximal exercise duration and/or maximal attained work load) during an EXERCISE TEST.
Clock Proteins
Basic helix-loop-helix (bHLH) domain-containing proteins that contain intrinsic HISTONE ACETYLTRANSFERASE activity and play important roles in CIRCADIAN RHYTHM regulation. Clock proteins combine with Arntl proteins to form heterodimeric transcription factors that are specific for E-BOX ELEMENTS and stimulate the transcription of several E-box genes that are involved in cyclical regulation. This transcriptional activation also sets into motion a time-dependent feedback loop which in turn down-regulates the expression of clock proteins.
Nuclear Receptor Subfamily 1, Group D, Member 1
A DNA-binding orphan nuclear receptor that negatively regulates expression of ARNTL TRANSCRIPTION FACTORS and plays a role as a regulatory component of the circadian clock system. The Nr1d1 nuclear receptor expression is cyclically-regulated by a feedback loop involving its positive regulation by CLOCK PROTEIN; BMAL1 PROTEIN heterodimers and its negative regulation by CRYPTOCHROME and PERIOD PROTEINS.
Zebrafish Proteins
Proteins obtained from the ZEBRAFISH. Many of the proteins in this species have been the subject of studies involving basic embryological development (EMBRYOLOGY).
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