Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free:

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site:, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Google Analytics

Targeted advertising cookies


The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at or by post at:

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

Concurrent BMP Signaling Maintenance and TGF-β Signaling Inhibition Is a Hallmark of Natural Resistance to Muscle Atrophy in the Hibernating Bear. Cussonneau, L.; Boyer, C.; Brun, C.; Deval, C.; Loizon, E.; Meugnier, E.; Gueret, E.; Dubois, E.; Taillandier, D.; Polge, C.; Bechet, D.; Gauquelin-Koch, G.; Evans, AL.; Arnemo, JM.; Swenson JE.; Blanc, S.; Simon, C.; Lefai, E.; Bertile, F.; Combaret,L. Cells 2021, 10, 1873.

Cardiomyocyte Protection by Hibernating Brown Bear Serum: Toward the Identification of New Protective Molecules Against Myocardial Infarction. Givre L, Crola Da Silva C, Swenson JE, Arnemo JM, Gauquelin-Koch G, Bertile F, Lefai E, Gomez L. Front Cardiovasc Med. 2021 Jul 16;8:687501. doi: 10.3389/fcvm.2021.687501.

Specific shifts in the endocannabinoid system in hibernating brown bears. Boyer C, Cussonneau L, Brun C, Deval C, Pais de Barros JP, Chanon S, Bernoud-Hubac N, Daira P, Evans AL, Arnemo JM, Swenson JE, Gauquelin-Koch G, Simon C, Blanc S, Combaret L, Bertile F, Lefai E. Front Zool. 2020 Nov 23;17(1):35. doi: 10.1186/s12983-020-00380-y.

MicroRNAs facilitate skeletal muscle maintenance and metabolic suppression in hibernating brown bears. Luu BE, Lefai E, Giroud S, Swenson JE, Chazarin B, Gauquelin-Koch G, Arnemo JM, Evans AL, Bertile F, Storey KB. J Cell Physiol. 2020 Apr;235(4):3984-3993. doi: 10.1002/jcp.29294. Epub 2019 Oct 23.  

Metabolic reprogramming involving glycolysis in the hibernating brown bear skeletal muscle. Chazarin B, Storey KB, Ziemianin A, Chanon S, Plumel M, Chery I, Durand C, Evans AL, Arnemo JM, Zedrosser A, Swenson JE, Gauquelin-Koch G, Simon C, Blanc S, Lefai E, Bertile F. Front Zool. 2019 May 6;16:12. doi: 10.1186/s12983-019-0312-2. eCollection 2019. PMID: 31080489 Free PMC article.

Lipidomics Reveals Seasonal Shifts in a Large-Bodied Hibernator, the Brown Bear. Giroud S, Chery I, Bertile F, Bertrand-Michel J, Tascher G, Gauquelin-Koch G, Arnemo JM, Swenson JE, Singh NJ, Lefai E, Evans AL, Simon C, Blanc S. Front Physiol. 2019 Apr 12;10:389. doi: 10.3389/fphys.2019.00389. eCollection 2019.  

Seasonal changes in eicosanoid metabolism in the brown bear. 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. Naturwissenschaften. 2018 Sep 17;105(9-10):58. doi: 10.1007/s00114-018-1583-8. PMID: 30291454 Free PMC article. 

Proteolysis inhibition by hibernating bear serum leads to increased protein content in human muscle cells. 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. Sci Rep. 2018 Apr 3;8(1):5525. doi: 10.1038/s41598-018-23891-5.


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