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- Title
Muscle IGF-1-Induced Skeletal Muscle Hypertrophy Evokes Higher Insulin Sensitivity and Carbohydrate Use as Preferential Energy Substrate.
- Authors
Christoffolete, Marcelo Augusto; Silva, William Jose; Ramos, Gracielle Vieira; Bento, Mirella Ribeiro; Costa, Monique Oliveira; Ribeiro, Miriam Oliveira; Okamoto, Maristela Mitiko; Lohmann, Tania Helena; Machado, Ubiratan Fabres; Musarò, Antonio; Moriscot, Anselmo Sigari
- Abstract
We characterized the metabolic profile of transgenic mice exhibiting enhanced muscle mass driven by increased mIGF-1 expression (MLC/mIGF-1). As expected, 6-month-old MLC/mIGF-1 mice were heavier than age-matched wild type (WT) mice (37.4 ± 0.3 versus 31.8 ± 0.6 g, resp.). MLC/mIGF-1 mice had higher respiratory quotient when compared to WT (0.9 ± 0.03 versus 0.74 ± 0.02, resp.) suggesting a preference for carbohydrate as the major fuel source. MLC/mIGF-1 mice had a higher rate of glucose disposal when compared to WT (3.25 ± 0.14 versus 2.39 ± 0.03%/min, resp.). The higher disposal rate correlated to ∼2-fold higher GLUT4 content in the extensor digitorum longus (EDL) muscle. Analysis of mRNA content for the glycolysis-related gene PFK-1 showed ∼3-fold upregulation in MLC/mIGF-1 animals. We also found a 50% downregulation of PGC1α mRNA levels in MLC/mIGF-1 mouse EDL muscle, suggesting less abundant mitochondria in this tissue. We found no difference in the expression of PPARα and PPARβ/δ, suggesting no modulation of key elements in oxidative metabolism. These data together suggest a shift in metabolism towards higher carbohydrate utilization, and that could explain the increased insulin sensitivity of hypertrophied skeletal muscle in MLC/mIGF-1 mice.
- Subjects
BLOOD sugar analysis; TYPE 2 diabetes diagnosis; ANIMAL experimentation; CARBOHYDRATES; CHOLESTEROL; ENERGY metabolism; FASTING; INSULIN resistance; MICE; MUSCLES; POLYMERASE chain reaction; PROTEINS; RESEARCH funding; SOMATOMEDIN; TRIGLYCERIDES; WESTERN immunoblotting; DATA analysis; OXIDATIVE stress; SKELETAL muscle; MUSCULAR hypertrophy; DESCRIPTIVE statistics; GENOTYPES
- Publication
BioMed Research International, 2015, Vol 2015, p1
- ISSN
2314-6133
- Publication type
Article
- DOI
10.1155/2015/282984