Relationship between preferred ambient temperature and autonomic thermoregulatory function in rat

Area of Science:

• Physiology
• Animal Behavior
• Thermoregulation

Background:

• Understanding thermoregulation is crucial for animal physiology research.
• Behavioral and autonomic responses are key components of thermoregulation.
• Rodent models offer insights into mammalian thermal regulation.

Purpose of the Study:

• To investigate the relationship between behavioral and autonomic thermoregulation in Sprague-Dawley (SD), Long-Evans (LE), and Fischer (FCH) rat strains.
• To determine preferred ambient temperatures (Ta) and thermoregulatory responses across different Ta.
• To compare thermoregulatory efficiency among the three rat strains.

Main Methods:

• Rats were exposed to a temperature gradient to record preferred Ta.
• Metabolic rate (MR), evaporative water loss (EWL), thermal conductance (C), and colonic temperature (Tcol) were measured at various Ta.
• Experiments were conducted on adult SD, LE, and FCH rat strains.

Main Results:

• Mean preferred Ta varied by strain: SD (24.9°C), LE (19.8°C), FCH (23.4°C).
• All strains showed minimal MR at 30°C, with increased MR at lower Ta.
• EWL and C increased with Ta, while Tcol was maintained between 14-30°C.
• FCH strain demonstrated superior Tcol control above 30°C.

Conclusions:

• Rat preferred Ta is below the lower critical Ta for metabolic heat production, suggesting unique thermoregulatory adaptations.
• Strain differences exist in preferred Ta and thermoregulatory capacity.
• These findings contribute to understanding rodent thermoregulation and its implications in physiological research.