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Glycogen and nonspecific adaptation to cold
Summary
Cold exposure and other stresses like swimming or fasting enhance cold resistance by altering glycogen stores. This adaptation, peaking 24 hours after stress, suggests glycogen is key to cold tolerance.
Area of Science:
- Physiology
- Metabolism
- Environmental Adaptation
Background:
- Moderate cold induces nonshivering thermogenesis in brown adipose tissue.
- Severe cold adaptation involves different mechanisms, confirmed in mice.
- Cold adaptation can be nonspecific, induced by other stressors like swimming or fasting.
Purpose of the Study:
- To investigate the mechanisms of cold adaptation induced by severe cold exposure.
- To explore the nonspecific nature of cold adaptation.
- To determine the role of glycogen stores in cold resistance.
Main Methods:
- Mice were subjected to repeated cold exposure, swimming, or fasting.
- Glycogen levels in liver and muscles were measured immediately after stress and 24 hours later.
- Cold tolerance was assessed by resistance to hypothermia.
Main Results:
- All stressors (cold, swimming, fasting) initially reduced glycogen stores.
- Glycogen levels significantly increased above baseline 24 hours after stress.
- Cold tolerance improved only when tested 24 hours post-stress.
Conclusions:
- Cold resistance adaptation is nonspecific and can be induced by various stressors.
- Glycogen stores play a crucial role in cold resistance.
- Glycogen may act as a rate-limiting substrate in cold adaptation.