Differences in Activity Patterns of Two Rat Strains
Author Information
Author(s): Cheryl D. Seroka, Cynthia E. Johnson, Paul D. Heideman
Primary Institution: College of William and Mary
Hypothesis
Strain variation in photoperiodism between photoperiodic F344 rats and nonphotoperiodic Harlan Sprague Dawley (HSD) rats might be caused by underlying variation in clock function.
Conclusion
The study suggests that differences in photoresponsiveness between F344 and HSD rats are likely due to non-circadian differences in melatonin secretion or response to melatonin.
Supporting Evidence
- HSD rats had significantly greater activity during the day compared to F344 rats.
- HSD rats were sometimes arrhythmic in constant darkness.
- HSD rats had significantly longer free-running rhythms than F344 rats.
Takeaway
Some rats are more active at night, while others are more active during the day, and this can be linked to how they respond to light and melatonin.
Methodology
The study compared activity rhythms of young male F344 and HSD rats in different light conditions using running wheels.
Limitations
The study was limited to young male rats and may not generalize to other ages or sexes.
Participant Demographics
Young male F344 and HSD rats.
Statistical Information
P-Value
p<0.0001
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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