How do rats tolerate cold? - briefly
Rats preserve body temperature with a high metabolic rate and dense fur. They can also enter torpor, reducing metabolic demand during extended cold exposure.
How do rats tolerate cold? - in detail
Rats maintain body temperature in low‑ambient conditions through a combination of physiological and behavioral mechanisms.
Thermoregulatory physiology includes rapid peripheral vasoconstriction, which reduces heat loss from the extremities while preserving core temperature. Shivering thermogenesis generates heat via involuntary muscle contractions, whereas non‑shivering thermogenesis relies on brown adipose tissue (BAT). BAT cells oxidize fatty acids and release heat through uncoupled mitochondrial respiration, a process up‑regulated by sympathetic nervous system activation and thyroid hormone signaling.
Metabolic rate rises markedly during cold exposure; oxygen consumption can increase two‑ to threefold, providing additional endogenous heat. Hormonal responses, such as elevated norepinephrine and cortisol, support gluconeogenesis and glycogenolysis, supplying substrates for thermogenic pathways.
Behavioral adaptations complement physiological responses. Rats seek insulated microhabitats, constructing nests from shredded material that trap warm air. Group huddling further reduces individual heat loss by sharing body warmth. Seasonal fur changes—denser, longer guard hairs and a thicker undercoat—enhance insulation.
When temperatures fall below the lower critical temperature, some rodent species enter a state of shallow torpor, lowering metabolic demand while maintaining sufficient brain function. Although true deep torpor is rare in common laboratory rats, brief periods of reduced activity and lowered body temperature have been observed, allowing energy conservation without compromising survival.
Overall, cold endurance in rats results from coordinated vascular control, heat‑producing tissue activation, metabolic acceleration, hormonal regulation, and strategic use of shelter and social behavior.