IGF-1 splice variant and IGF-1 peptide expression patterns in young and old human skeletal muscle prior to and following sequential exercise bouts

• Published in: European journal of applied physiology 2010-11, Vol.110 (5), p.961-969
• Main Authors: Roberts, Michael D., Dalbo, Vincent J., Sunderland, Kyle L., Poole, Chris N., Hassell, Scott E., Bemben, Debra, Cramer, Joel, Stout, Jeff, Kerksick, Chad M.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age groups; Aged; Alternative Splicing; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cell growth; Exercise - physiology; Fundamental and applied biological sciences. Psychology; Gene Expression; Human Physiology; Humans; Insulin-Like Growth Factor I - biosynthesis; Insulin-Like Growth Factor I - genetics; Insulin-like growth factors; Kinases; Male; Middle Aged; Muscle, Skeletal - chemistry; Muscle, Skeletal - metabolism; Musculoskeletal system; Occupational Medicine/Industrial Medicine; Original Article; Peptides; Physical fitness; Protein Isoforms - biosynthesis; Protein Isoforms - genetics; Protein synthesis; Proteins; Quadriceps Muscle - chemistry; Quadriceps Muscle - metabolism; Research design; Resistance Training; Sports Medicine; Strength training; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Young Adult
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-010-1588-2

Genes and proteins involved in insulin-like growth factor (IGF)-1 signaling are thought to be differentially expressed in older versus younger mammalian skeletal muscle following acute exercise. The purpose of this study was to examine how multiple bouts of conventional resistance training meant to elicit hypertrophy affect the mRNA expression of IGF - 1EA and IGF - 1EC ( MGF ) as well as the expression of total IGF-1 peptides in human skeletal muscle. Ten younger (18–25 years) and 10 older (60–75 years) males completed three sequential workouts (M, W, F) consisting of nine sets of lower body exercises with ten repetitions per set at an intensity of 80% of one repetition maximum. Vastus lateralis muscle biopsies were collected prior to intervention (T1), 48 h following workout 1 (T2), 48 h following workout 2 (T3), and 24 h following workout 3 (T4). RT-PCR was performed to assess baseline and changes in MGF and IGF - IEA mRNA. Samples were also assayed for total muscle IGF-1 peptides using ELISA-based methods. There were no baseline differences in MGF or IGF - 1EA mRNA expression and IGF-1 peptides between age groups. Interestingly, MGF expression increased at T2–T4 in the older group relative to baseline values ( p