[Chronic exposure to cold is adaptation without stress ]

Area of Science:

• Physiology
• Environmental Medicine

Background:

• Cold exposure is a known physiological stressor.
• Different durations and patterns of cold exposure may elicit varied biological responses.

Purpose of the Study:

• To investigate the effects of varying cold exposure regimens on rat physiology.
• To determine impacts on organ weights, gastric health, and stress hormone levels.

Main Methods:

• Rats were subjected to three different cold exposure protocols: prolonged continuous, chronic intermittent, and short-term intermittent.
• Organ weights (brown fat, adrenal gland, spleen, kidneys, heart), gastric ulcer incidence, and serum cortisol/corticosterone levels were measured.

Main Results:

• Prolonged continuous cold (+4°C, 24h/day) increased brown fat and adrenal gland weight without altering hormone levels or causing ulcers.
• Chronic intermittent cold (+4°C, 8h/day) increased brown fat, spleen, kidney, and heart weights, induced stomach ulcers, and altered hormone levels.
• Short-term intermittent cold (+4°C, 1.5h/day) increased body, spleen, kidney, and heart weights but did not affect brown fat, hormone levels, or cause ulcers.

Conclusions:

• The duration and pattern of cold exposure significantly influence physiological adaptations in rats.
• Intermittent cold exposure, even short-term, can induce gastric pathology and alter stress hormone profiles, suggesting a distinct stress response compared to continuous exposure.