Abstract(s) :

(Anglais) Exercise training (ET) has a positive effect on brain health. Although molecular mechanisms underlying ET benefits are still poorly understood, a cross-talk between skeletal muscle and brain has been described. During ET, muscle releases specific myokines among which potential regulators of hippocampal function, like Irisin. This exerkine is a PGC1α-dependant myokine released by cleavage of FNDC5. Also expressed in the brain, FNDC5 contributes to increase the level of brain-derived neurotrophic factor. However, the contribution of muscle-derived Irisin on cognitive function remains controversial, as the influence of obesity or ET modalities. The goal of our study is to determine (i) inter-relationships between FNDC5/Irisin pathway and cognition in function of ET modalities and (ii) whether muscle-to-brain crosstalk is altered in the context of obesity. To this aim, two ET modalities were compared in mice: spontaneous ET (environmental enrichment) and endurance ET (training sessions on a treadmill). Mice were fed either with a Low-Fat (LF) or an High-Fat (HF) diet. ET reduces weight gain and fasting glycaemia in obese mice. Environmental enrichment improves spatial learning and memory (Morris Water Maze test), particularly in obese animals. Irisin plasmatic level is enhanced by a HF diet and endurance ET. In muscles, FNDC5 protein level is also modified by ET and diet. In brain, ET improves BDNF protein level. In conclusion, ET modalities and obesity influence FNDC5/Irisin pathway and cognitive functions in mice. Further studies are necessary to understand the contribution of muscle-derived Irisin to ET effects.