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Metabolic adaptations during torpor

Many animals can slow down their metabolism to enter low-energy states. This condition - characterized by reduced body temperature, metabolic rate and complete inactivity - is known as torpor. Hibernation, or successive torpor bouts, is a powerful energy-saving strategy, and is associated with strong physiological adaptations. During hibernation, animals fuel their energy needs by specifically mobilizing lipid sources, notably of low unsaturation, keeping unsaturated fatty acids in their membranes for proper functioning of organs, e.g. heart or brain, and spare proteins.

Interestingly, hibernators and heterotherms do not suffer from any significant loss of muscle mass or change in bone structure, nor they suffer from oxidative damage or other deleterious effects during hibernation. Upon rewarming, dramatic metabolic changes also occur, organs and tissues are rapidly re-perfused, while metabolic and oxidative processes rise to a peak. Among the most impressive adaptations, during a torpor state, the heart continues to beat into sinus rhythm, despite heart rate is reduced to single-digits, the cardiovascular system undergoes drastic modifications, while the cellular metabolism is reduced to a minimum.

By contrast, some domestic animals, e.g. cats, dogs or pigs, have higher susceptibilities for cardiovascular diseases linked to metabolic disorders. Following the concept of comparative physiology, we are studying the metabolic adaptations, notably those linked to lipid metabolism, of hibernating animals, as a biomimicry strategy to fuel new ideas for translational research. This research of biomimicry is notably of great interest for biomedical applications, including treatments for cardiovascular diseases or metabolic disorders such as obesity in both animals and humans.