Skeletal muscle growth in young rats is inhibited by chronic exposure to IL-6 but preserved by concurrent voluntary endurance exercise

P. W. Bodell, E. Kodesh, F. Haddad, F. P. Zaldivar, D. M. Cooper, G. R. Adams

Research output: Contribution to journalArticlepeer-review


Childhood diseases are often accompanied by chronic inflammation, which is thought to negatively impact growth. Interleukin-6 (IL-6) is typically cited as an indicator of inflammation and is linked to impaired growth. This study was designed to isolate and identify potential effects of chronic IL-6 exposure on skeletal muscle growth during development. A second aim was to determine if endurance exercise, thought to antagonize chronic inflammation, would interact with any effects of IL-6. The muscles of one leg of rapidly growing rats were exposed to IL-6 or vehicle for 14 days. Subgroups of IL-6-infused rats were provided access to running wheels. Local IL-6 infusion resulted in ∼13% muscle growth deficit (myofibrillar protein levels). Exercise (>4,000 m/day) prevented this deficit. IL-6 infusion increased mRNA for suppressor of cytokine signaling-3 (SOCS3) and tumor necrosis factor-α (TNF-α), and this was not prevented by exercise. IL-6 infusion increased the mRNAs for atrogin, insulin-like growth factor-I (IGF-I), and IGF binding protein-4 (IGFBP4), and these effects were mitigated by exercise. Exercise stimulated an increase in total RNA (∼19%) only in the IL-6-infused muscle, suggesting that a compensatory increase in translational capacity was required to maintain muscle growth. This study indicates that IL-6 exposure during periods of rapid growth in young animals can retard growth possibly via interactions with key growth factors. Relatively high volumes of endurance-type exercise do not exacerbate the negative effects of IL-6 and in fact were found to be beneficial in protecting muscle growth.

Original languageEnglish
Pages (from-to)443-453
Number of pages11
JournalJournal of Applied Physiology
Issue number2
StatePublished - Feb 2009
Externally publishedYes


  • Cytokine
  • Inflammation
  • Protection
  • Running

ASJC Scopus subject areas

  • Physiology (medical)
  • Physiology


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