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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal logo Université Clermont Auvergne & associés

Human Nutrition Unit

Zone de texte éditable et éditée et rééditée

Etienne LEFAI

Etienne LEFAI


ORCID : 0000-0002-3042-7801

RESEARCHER ID: E-9615-2019

Tel : +33 (0)4 73 62 47 44


The hibernating brown bear, a model for the biomedical research

bear summer capture

Research topics

Muscle atrophy, i.e. the progressive loss of muscle mass, occurs with lack of physical activity, in sedentary behavior, under immobilization or during natural aging. In human pathology, muscle atrophy is also observed in several chronic diseases as cancer, renal or cardiac failures, and also in neuromuscular pathologies.

Unfortunately, to face these major public health concerns and in the context of aging population, there are still no efficient therapeutic strategies to preserve muscle mass and to fight against muscle loss.

The Scandinavian brown bear (Ursus arctos) remains inactive in winter during up to seven months without arousal episodes and without eating, drinking, urinating or defecating, with only very limited loss in muscle protein content and strength, whereas muscle and fibre cross-sectional area is preserved. Hibernating bears thus exhibit a strong and unique ability to preserve muscle mass in conditions of muscle disuse and food deprivation, conditions during which muscle atrophy is observed in human.

Thanks to a collaborative network involving several European academic laboratories with access to bear samples thanks to the SBBRG (, we are developing a research program aiming at the characterization of the bear serum potential to impact human muscle cell physiology. We explore the mechanisms by which the bears successfully spare its muscle proteins during up to 7 months of inactivity during winter hibernation.

Twice a year, in winter and summer, all scientists meet in the Swedish boreal forest to capture free living bears and collect samples.

ours anesth 2

Underlying mechanisms have not been understood yet, but our recent demonstration of trans-species effects of bear serum controlling protein degradation in cultured human muscle cell holds promising potential. By inducing a hibernation-like phenotype in human muscle cells, winter bear serum, therefore, holds potential for developing new tools to fight human muscle atrophy and related metabolic disorders.

patte ours

The project is also on screen

See the teaser of the 52' documentary " The superpower of the bears"

Teaser on Vimeo

ARTE /Le cinquieme reve (T. Robert and R. Marion Directors)

Selected recent publications

Giroud S, Chery I, Bertile F, Bertrand-Michel J, Tascher G, Gauquelin-Koch G, Arnemo J M., Swenson J E, Singh N J., Lefai E, Evans A L., Simon Cl, Blanc S. Lipidomics Reveals Seasonal Shifts in a Large-Bodied Hibernator, the Brown Bear. Front. Physiol. 2019. 10, 389.  DOI=10.3389/fphys.2019.00389

Chanon S, Chazarin B, Toubhans B, Durand C, Chery I, Robert M, Vieille-Marchiset A, Swenson JE, Zedrosser A, Evans AL, Brunberg S, Arnemo JM, Gauquelin-Koch G, Storey KB, Simon C, Blanc S, Bertile F, Lefai E. Proteolysis inhibition by hibernating bear serum leads to increased protein content in human muscle cells. Sci Rep. 2018 Apr 3;8(1):5525. doi: 10.1038/s41598-018-23891-5.

Giroud S, Evans AL, Chery I, Bertile F, Tascher G, Bertrand-Michel J, Gauquelin-Koch G, Arnemo JM, Swenson JE, Lefai E, Blanc S, Simon C. Seasonal changes in eicosanoid metabolism in the brown bear. Naturwissenschaften. 2018 Sep 17;105(9-10):58. doi: 10.1007/s00114-018-1583-8.

Loizides-Mangold U, Perrin L, Vandereycken B, Betts JA, Walhin JP, Templeman I, Chanon S, Weger BD, Durand C, Robert M, Paz Montoya J, Moniatte M, Karagounis LG, Johnston JD, Gachon F, Lefai E, Riezman H, Dibner C. Lipidomics reveals diurnal lipid oscillations in human skeletal muscle persisting in cellular myotubes cultured in vitro. Proc Natl Acad Sci U S A. 2017 Oct 10;114(41):E8565-E8574. doi: 10.1073/pnas.1705821114. Epub 2017 Sep 25. 8

Benoit B, Meugnier E, Castelli M, Chanon S, Vieille-Marchiset A, Durand C, Bendridi N, Pesenti S, Monternier PA, Durieux AC, Freyssenet D, Rieusset J, Lefai E, Vidal H, Ruzzin J. Fibroblast growth factor 19 regulates skeletal muscle mass and ameliorates muscle wasting in mice. Nat Med. 2017 Aug;23(8):990-996. doi: 10.1038/nm.4363. Epub 2017 Jun 26.


INRA 4-4, the Proteostasis STRAVA team for runners !