Activation of insulin-like growth factor gene expression during work-induced skeletal muscle growth

D. L. DeVol, P. Rotwein, J. L. Sadow, J. Novakofski, P. J. Bechtel

    Research output: Contribution to journalArticlepeer-review

    281 Scopus citations

    Abstract

    We have investigated the hypothesis that there is local regulation of insulin-like growth factor (IGF) gene expression during skeletal muscle growth. Compensatory hypertrophy was induced in the soleus, a predominately slow-twitch muscle, and plantaris, a fast-twitch muscle, in 11- to 12-wk-old female Wistar rats by unilateral cutting of the distal gastrocnemius tendon. Animals were killed 2, 4, or 8 days later, and muscles of the nonoperated leg served as controls. Muscle weight increased throughout the experimental period, reaching 127% (soleus) or 122% (plantaris) or control values by day 8. In both growing muscles, IGF-I mRNA, quantitated by a solution-hybridization nuclease-protection assay, rose by nearly threefold on day 2 and remained elevated throughout the experimental period. IGF-II mRNA levels also increased over controls. A moredramatic response was seen in hypophysectomized rats, where IGF-I mRNA levels rose by 8- to 13-fold, IGF-II values by 3- to 7-fold, and muscle mass increased on day 8 to 149% (soleus) or 133%( plantaris) of the control contralateral limb. These results indicate that signals propagated during muscle hypertrophy enhance the expression of both IGF genes, that modulation of IGF-I mRNA levels can occur in the absence of growth hormone, and that locally produced IGF-I and IGF-II may play a role in skeletal muscle growth.

    Original languageEnglish (US)
    Pages (from-to)E89-E95
    JournalAmerican Journal of Physiology - Endocrinology and Metabolism
    Volume259
    Issue number1 22-1
    DOIs
    StatePublished - 1990

    Keywords

    • growth hormone
    • growth regulation
    • hypophysectomy
    • muscle hypertrophy
    • pituitary-intact rats
    • somatomedins

    ASJC Scopus subject areas

    • Endocrinology, Diabetes and Metabolism
    • Physiology
    • Physiology (medical)

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