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 journalArticle

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)

Fingerprint Dive into the research topics of 'Activation of insulin-like growth factor gene expression during work-induced skeletal muscle growth'. Together they form a unique fingerprint.

  • Cite this