Endurance Exercise Modifies the Circadian Clock in Zebrafish (Danio rerio) Temperature Independently
- Authors
- Egg, M., Tischler, A., Schwerte, T., Sandbichler, A., Folterbauer, C., and Pelster, B.
- ID
- ZDB-PUB-111115-8
- Date
- 2012
- Source
- Acta physiologica (Oxford, England) 205(1): 167-176 (Journal)
- Registered Authors
- Pelster, Bernd, Schwerte, Thorsten
- Keywords
- gene transcription, circadian clock, zebrafish, training, zeitgeber, temperature
- MeSH Terms
-
- Animals
- Body Temperature/physiology*
- Circadian Clocks/physiology*
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Period Circadian Proteins/genetics
- Period Circadian Proteins/metabolism
- Physical Conditioning, Animal/physiology*
- Physical Endurance/physiology*
- Zebrafish/physiology*
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism
- PubMed
- 22044585 Full text @ Acta Physiol. (Oxf).
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.