Exercise during intermittent cold exposure prevents acclimation to cold rats

Area of Science:

• Physiology
• Metabolism
• Brown Adipose Tissue Biology

Background:

• Understanding energy balance and brown adipose tissue (BAT) adaptations is crucial for metabolic health.
• Exercise and cold exposure are known modulators of energy expenditure and BAT activity.
• Investigating their combined effects provides insight into thermoregulation and metabolic regulation.

Purpose of the Study:

• To examine the effects of exercise training and cold exposure, both individually and in combination, on energy balance and BAT growth in male Wistar rats.
• To determine if exercise training mitigates or alters cold-induced adaptations in energy metabolism and body composition.
• To assess the impact of combined stressors on BAT hypertrophy and function.

Main Methods:

• Four groups of male Wistar rats were used: sedentary warm-acclimated, exercise-trained warm-acclimated, sedentary cold-exposed, and exercise-trained cold-exposed.
• Rats were exposed to either 24°C or -5°C for 2 hours daily for 28 days.
• Measurements included body mass gain, body composition (protein, fat), metabolizable energy intake, energy expenditure, and brown adipose tissue (BAT) protein and deoxyribonucleic acid (DNA) content.

Main Results:

• Exercise training with cold exposure did not significantly affect body composition compared to exercise training alone.
• Sedentary cold-exposed rats exhibited lower body mass, protein, and fat gains but significantly increased metabolizable energy intake and energy expenditure.
• Brown adipose tissue (BAT) total protein and DNA content more than doubled in sedentary cold-exposed rats, indicating significant hypertrophy, an effect not observed in exercise-trained cold-exposed rats.

Conclusions:

• Cold exposure significantly impacts energy balance and promotes BAT growth in sedentary rats.
• Exercise training during cold exposure appears to prevent typical cold acclimation responses, including BAT hypertrophy and increased energy expenditure.
• Combined exercise and cold stress do not enhance body composition benefits over exercise alone, suggesting distinct physiological pathways are engaged.