Temperature dependence of the hamster circadian pacemaker

Area of Science:

• Chronobiology
• Animal Physiology

Background:

• Circadian rhythms govern daily physiological and behavioral cycles.
• The impact of hypothermia on circadian pacemakers is not fully understood.

Purpose of the Study:

• To investigate the effect of induced hypothermia on the circadian pacemaker of male Syrian hamsters.
• To quantify the temperature sensitivity (Q10) of the hamster circadian clock during hypothermia.

Main Methods:

• Male Syrian hamsters were subjected to controlled hypothermia (10-20°C for 3-24 hours) after establishing baseline running-wheel activity.
• Locomotor activity was monitored post-rewarming to assess phase shifts in activity onset.
• The rate of the circadian clock during hypothermia was calculated using Q10 values.

Main Results:

• Hypothermia induced significant phase delays in locomotor activity onset.
• The magnitude of the phase shift correlated with hypothermia duration and temperature.
• Calculated Q10 values ranged from 1.08 to 1.34, indicating reduced clock speed during hypothermia.

Conclusions:

• The circadian pacemaker in hamsters operates at a reduced rate during hypothermia.
• Hamster circadian pacemakers exhibit superior temperature compensation compared to rats.