Leptin Administration Favors Muscle Mass Accretion by Decreasing FoxO3a and Increasing PGC-1α in ob/ob Mice

Absence of leptin has been associated with reduced skeletal muscle mass in leptin-deficient ob/ob mice. The aim of our study was to examine the effect of leptin on the catabolic and anabolic pathways regulating muscle mass. Gastrocnemius, extensor digitorum longus and soleus muscle mass as well as fiber size were significantly lower in ob/ob mice compared to wild type littermates, being significantly increased by leptin administration (P<0.001). This effect was associated with an inactivation of the muscle atrophy-related transcription factor forkhead box class O3 (FoxO3a) (P<0.05), and with a decrease in the protein expression levels of the E3 ubiquitin-ligases muscle atrophy F-box (MAFbx) (P<0.05) and muscle RING finger 1 (MuRF1) (P<0.05). Moreover, leptin increased (P<0.01) protein expression levels of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a regulator of muscle fiber type, and decreased (P<0.05) myostatin protein, a negative regulator of muscle growth. Leptin administration also activated (P<0.01) the regulators of cell cycle progression proliferating cell nuclear antigen (PCNA) and cyclin D1, and increased (P<0.01) myofibrillar protein troponin T. The present study provides evidence that leptin treatment may increase muscle mass of ob/ob mice by inhibiting myofibrillar protein degradation as well as enhancing muscle cell proliferation

Short-Term Pilot Study of the Effect of Sleeve Gastrectomy on Food Preference

The effect of vertical sleeve gastrectomy (VSG) on food preference has not been examined in humans, but VSG decreases preference for fat and calorically dense foods in rodents. A validated Food Preference Questionnaire (FPQ) assessed food preference changes before and 6-weeks after VSG in humans. The FPQ was completed before and 43 ± 19 days (Mean ± SD) after VSG. Fifteen subjects (14 females) completed the study. Hedonic ratings decreased for foods high in fat and sugar (p = 0.002) and high in fat and complex carbohydrate (p = 0.007). Fat preference (p = 0.048) decreased, VSG reduced preference for calorically dense foods high in fat, sugar and complex carbohydrate, and these changes may contribute to the weight loss with VSG