Enhanced muscle mixed and mitochondrial protein synthesis rates after a high-fat or high-sucrose diet.
OBJECTIVE
Obesity and insulin resistance are associated with muscle mitochondrial dysfunction, which might be related to impairment of mitochondrial protein synthesis. This study aimed at investigating mixed and mitochondrial protein synthesis in skeletal muscle in response to dietary manipulations.


METHODS
High-sucrose (SU) and high-fat, high-sucrose (F) diets were provided for 6 weeks to Wistar rats at standard (N) and high (H) energy intakes and compared with controls. Fractional synthesis rates of mixed (FSRPT) and mitochondrial (FSRm) proteins within the oxidative (soleus) and glycolytic (tibialis) muscles were measured using stable isotope flooding dose technique using L-[13C]-valine. Carbonyl content, citrate synthase, and cytochrome c oxidase activities were assayed spectrophotometrically on isolated mitochondria.


RESULTS
In the soleus, FSRPT was increased by 40% in the NSU and NF groups and by 65% in the HSU and HF groups (p<0.001 vs. control). FSRm was increased with high-fat diets (NF, +16%; HF, +32%; p<0.01). In the tibialis, FSR(PT) was enhanced in all experimental groups (+31% to 37%, p<0.05 vs. control). FSRm was augmented in the NSU, NF, and HF groups (+28% to 32%, p<0.01). Cytochrome c oxidase activity was significantly decreased in all experimental groups in the soleus (p<0.001).


CONCLUSIONS
Muscle mixed and mitochondrial protein FSR are enhanced after short-term dietary intervention known to induce insulin resistance and obesity. Adaptations are muscle type specific and may not explain alterations in mitochondrial oxidative capacity but might contribute to maintain mitochondrial functioning.
Chanseaume
Emilie
E
Lipid and Energy Metabolism Research Unit, Human Nutrition Laboratory, Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1019, Clermont-Ferrand cedex 1, France.
Giraudet
Christophe
C
Gryson
Céline
C
Walrand
Stéphane
S
Rousset
Paulette
P
Boirie
Yves
Y
Morio
Béatrice
B
D000821:Animal Feed; D000818:Animals; D004041:Dietary Fats / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism; D002149:Energy Intake; D007333:Insulin Resistance; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D009132:Muscles / Q000473:pathology*; D009765:Obesity / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013395:Sucrose / Q000378:metabolism*
D004041:Dietary Fats; D024101:Mitochondrial Proteins; D013395:Sucrose; D003576:Electron Transport Complex IV