Core temperature is regulated, although at a lower temperature, in rats exposed to hypergravic fields

Area of Science:

• Physiology
• Gravitational Biology
• Environmental Physiology

Background:

• Thermoregulation is crucial for survival.
• Hypergravity may impact physiological processes, including temperature regulation.
• Acclimation to different ambient temperatures can influence an organism's response to environmental stressors.

Purpose of the Study:

• To investigate the effects of a hypergravic field on thermoregulation in rats.
• To compare the thermoregulatory responses of rats acclimated to different ambient temperatures (23°C vs. 5°C) under hypergravity.
• To assess core temperature (Tc), tail temperature (Tt), and oxygen consumption (VO2) during thermal challenges in a 3g field.

Main Methods:

• Rats acclimated to 23°C (RT) or 5°C (CA) were exposed to a 3g field for 5.5 hours.
• Ambient temperature (Ta) was manipulated: 25°C for 2 hours, then 34°C for 1.5 hours, followed by 25°C for 2 hours.
• A second experiment involved exposing rats to 12°C for 1 hour after an initial 2-hour period at 25°C.

Main Results:

• During warm exposure (34°C) in the 3g field, Tc increased by 4°C in both RT and CA rats.
• During cold exposure (12°C) in the 3g field, Tc fell by 1.5°C in RT rats and 0.5°C in CA rats.
• Following thermal challenges, Tc returned towards pre-exposure levels in both groups.

Conclusions:

• Rats exhibit thermoregulation in a 3g field, though potentially at a lower set point.
• Cold-acclimated rats demonstrated a more robust ability to maintain core temperature under hypergravity during cold stress.
• Prior thermal acclimation influences thermoregulatory capacity in hypergravic environments.