How do mice endure long relocations? - briefly
During prolonged transport, mice lower body temperature and metabolic rate, entering torpor to conserve energy. They mobilize stored fat and release stress hormones, maintaining physiological stability.
How do mice endure long relocations? - in detail
Mice survive prolonged transport through a combination of physiological resilience, behavioral strategies, and environmental management. Their small body mass reduces the absolute energy required for maintenance, while a high basal metabolic rate allows rapid mobilization of stored nutrients. During extended journeys, glycogen reserves in the liver and muscle are converted to glucose, supporting brain function and locomotion. When food intake ceases, lipolysis supplies fatty acids, which are oxidized to produce ATP, sustaining vital organs for days without external nourishment.
Thermoregulation contributes significantly to endurance. Mice possess dense fur and a high surface‑to‑volume ratio, which together enable efficient heat retention. Shivering thermogenesis, driven by uncoupling protein‑1 in brown adipose tissue, generates heat without muscular activity, conserving energy. In colder conditions, vasoconstriction limits heat loss, while in warm environments, evaporative cooling through panting and licking reduces core temperature.
Stress mitigation relies on the hypothalamic‑pituitary‑adrenal (HPA) axis. Corticosterone release prepares the animal for acute challenges, but chronic elevation is limited by feedback inhibition, preventing detrimental immunosuppression. Behavioral responses, such as clustering with conspecifics, lower individual stress levels through social thermoregulation and shared vigilance. When isolated, mice exhibit increased grooming and nesting behavior, constructing micro‑shelters from available materials to reduce exposure to drafts and predators.
Effective relocation protocols exploit these natural capacities:
- Pre‑transport acclimation: Gradual exposure to handling and confined spaces reduces HPA activation.
- Environmental control: Maintaining ambient temperature between 20 °C and 25 °C prevents hypothermia and hyperthermia.
- Ventilation: Ensuring fresh air flow supplies oxygen while removing carbon dioxide, avoiding respiratory distress.
- Hydration: Providing moist bedding or water‑impregnated wicks limits dehydration without requiring active drinking.
- Nutrient provision: Supplying a high‑energy gel or compact pellet sustains glucose levels during longer trips.
Empirical studies demonstrate survival rates exceeding 95 % for laboratory mice transported for up to 48 hours under controlled conditions. Mortality rises sharply when temperature falls below 15 °C or when ventilation is obstructed, confirming the critical role of environmental parameters. Continuous monitoring of body weight, corticosterone concentration, and behavior during and after relocation offers quantitative indicators of stress and recovery, guiding refinements in handling procedures.