Awede, Bonaventure L
[UCL]
Thissen, Jean-Paul
[UCL]
Lebacq, Jean
[UCL]
Clenbuterol induces hypertrophy and a slow-to-fast phenotype change in skeletal muscle, but the signaling mechanisms remain unclear. We hypothesized that clenbuterol could act via local expression of insulin-like growth factor I (IGF-I). Administration of clenbuterol to 3-mo-old female Wistar rats resulted in a 10 and 13% increase of soleus muscle mass after 3 and 9 days, respectively, reaching 16% after 4 wk. When associated with triiodothyronine, clenbuterol induced a dramatic slow-to-fast phenotype change. In parallel, clenbuterol administration induced in soleus muscle a fivefold increase in IGF-I mRNA levels associated with an eightfold increase in IGF-binding protein (IGFBP)-4 and a fivefold increase of IGFBP-5 mRNA levels on day 3. This increased IGF-I gene expression was associated with an increase in muscle IGF-I content, already detected on day 1 and persisting until day 5 without increase in serum IGF-I concentrations. These data show that muscle hypertrophy induced by clenbuterol is associated with a local increase in muscle IGF-I content. They suggest that clenbuterol-induced muscle hypertrophy could be mediated by local production of IGF-I.
Bibliographic reference |
Awede, Bonaventure L ; Thissen, Jean-Paul ; Lebacq, Jean. Role of IGF-I and IGFBPs in the changes of mass and phenotype induced in rat soleus muscle by clenbuterol.. In: American journal of physiology. Endocrinology and metabolism, Vol. 282, no. 1, p. E31-7 (2002) |
Permanent URL |
http://hdl.handle.net/2078.1/9010 |