Behavioral and physiologic responses to caloric restriction in mice

Area of Science:

• Physiology
• Metabolic Research
• Animal Behavior

Background:

• Standard vivarium temperatures (around 23°C) impose mild cold stress on mice, increasing metabolic rate and food intake.
• Mice exhibit unique thermoregulatory responses, including entering torpor (body temperature <31°C) when facing thermal or energetic challenges.

Purpose of the Study:

• To review the effects of ambient temperature (T(a)) and caloric restriction (CR) on mouse metabolism, cardiovascular function, and behavior.
• To highlight the importance of considering T(a) in experimental design for energy homeostasis and cardiovascular studies.

Main Methods:

• Review of existing literature on mouse physiology and behavior under varying ambient temperatures and caloric intake.
• Analysis of metabolic rate, heart rate, blood pressure, and locomotor activity in mice under different thermal and dietary conditions.

Main Results:

• Increasing ambient temperature to thermoneutrality (29-33°C) reduces food intake, metabolic rate, heart rate, and blood pressure.
• Caloric restriction at thermoneutral temperatures leads to physiological reductions in metabolic rate and heart rate but does not induce torpor.
• Locomotor activity responses to CR differ with T(a); increased activity at standard T(a) is diminished at thermoneutrality.

Conclusions:

• Ambient temperature is a critical factor influencing mouse physiology and behavior, particularly in studies of metabolism and cardiovascular function.
• Researchers must carefully control and report T(a) to ensure the validity and reproducibility of findings related to energy balance and cardiovascular parameters.