Metabolic Physiology

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. On the contrary, 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.

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The main collaborations for the development of this research line include Prof Kenneth Storey (Carleton University, Ottawa, CA), Prof Rob Henning (University of Groningen, NL), Dr Stéphane Blanc (CNRS Strasbourg, France), Dr Fabrice Bertile (CNRS Strasbourg, France), Prof Peter Stenwinkel (Karolinska Institute, Sweden), and Prof Jérémy Terrien (CNRS Brunoy, France), and Prof Yoshifumi Yamaguchi (Hokkaido University, Japan). This research is conducted on hibernators from small (hamsters, dormice) to large hibernators, such as bears.

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The video below describes how brown bears go into hibernation for up to seven months and come out just as healthy as they started. It explains how scientists bring bears out of their dens to find answers to this riddle. We are now getting closer to answers that may help solve some of our major public health problems, such as obesity, muscle atrophy, bone loss, and cardiovascular dysfunctions.