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Le sport module la densité des récepteurs de leptine sur les muscles

21/09/2013 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge

 

EXERCISE IS A LEPTIN SIGNALLING MIMETIC, AND WHEY PROTEIN INGESTION FACILITATES LEPTIN SIGNALLING IN HUMAN SKELETAL MUSCLE
J G. Ponce-González             Ann Nutr Metab 2013;63(suppl 1):1371

Leptin and leptin receptor (LEPR) polymorphisms have been associated with obesity and muscle hypertrophy. LEPRs are increased in the dominant
arm of tennis players. The aim of this study was to determine whether exercise up-regulates the expression of LEPRs and the leptin signaling cascade in arm and leg muscles.

Methods: Fifteen overweight men first performed 4 days of prolonged exercise (45min of one-arm cranking followed by 8h walking each day) with caloric restriction (0.8 g whey protein (PRO)
(n = 8) or sucrose (SU)(n = 7) per kg body weight each day) (designated PE+CR period). Thereafter followed 3 days of reduced exercise and balanced diet (isoenergetic with their usual
diet )(designated CD). Muscle biopsies from both deltoid and vastus lateralis (135 biopsies in all) were used to determine: LEPR mRNA, the protein levels of SOCS3 (inhibitor of leptin
signalling), and the total and phosphorylated levels of LEPR (Tyr1141 and Tyr985), JAK2, and STAT3.

Results: LEPR were more abundant in arm than leg muscles. Serum leptin was reduced by 64 and 50% following PE+CR and CD, respectively (P < 0.05). After PE+CR, LEPR mRNA was
increased in exercised muscles, but the protein expression of LEPR was increased only in the arms, more in the PRO than in the SU (P < 0.05). After CD, LEPR mRNA returned to basal
levels whilst LEPR expression was increased in all muscles (P < 0.05). The fraction of LEPR activated (Tyr1141 and Tyr985 phosphorylated) was reduced in arms but not in leg muscles.
LEPR phosphorylation was correlated with JAK2 (upstream kinase) and STAT3 (downstream kinase) phosphorylation (r=0.67-89, P < 0.05). SOCS3 remains unaltered in exercised
muscles.

Conclusions: The leptin signaling system is very active in human skeletal muscles. Exercise can be considered as a leptin mimetic because it increases the expression of LEPR and facilitates leptin signaling. Whey protein ingestion facilitates these
effects.

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