Body core temperature during food restriction in rats

Area of Science:

• Physiology
• Thermoregulation
• Animal Behavior

Background:

• Starvation and food restriction profoundly impact mammalian physiology.
• Understanding thermoregulatory adjustments is crucial for survival during nutritional deficits.
• Previous research indicates metabolic rate reduction during caloric deprivation.

Purpose of the Study:

• To investigate the effects of starvation and food restriction on deep body temperature and locomotor activity in rats.
• To compare the thermoregulatory responses between starved and food-restricted rats.
• To elucidate the role of thermal conductance in maintaining core body temperature during nutritional stress.

Main Methods:

• Implanted transmitters were used to continuously measure deep body temperature and locomotor activity in rats.
• Two experimental groups were established: food-restricted (reduced food amount) and starved.
• Both groups were subsequently refed ad libitum to observe recovery responses.

Main Results:

• Both starved and food-restricted rats exhibited significant reductions in deep body temperature, with a more pronounced decrease in starved rats.
• Starved rats displayed a displacement of their circadian temperature rhythm.
• Locomotor activity remained similar until refeeding; food-restricted rats recovered activity faster than starved rats.
• Thermal conductance decreased by 30% in both groups, potentially aiding in core temperature maintenance despite reduced metabolic rates.

Conclusions:

• Reduced body core temperature during starvation indicates a shift in the thermoregulatory set-point.
• Decreased thermal conductance is a key mechanism enabling rats to maintain near-normal core temperatures during prolonged fasting or semi-starvation.
• Differential recovery of locomotor activity suggests distinct physiological adaptations between starvation and food restriction.