Regulation of type IV collagen gene expression and degradation in fast and slow muscles during dexamethasone treatment and exercise.
Glucocorticoids have anti-anabolic effects on many tissues and can cause muscle atrophy. However, their effects on type IV collagen gene expression and degradation in skeletal muscle have not been studied previously. Rats were treated daily with dexamethasone or saline. Half the groups of experimental and control animals were also subjected to daily endurance or uphill running exercise to determine the possible preventive effects of exercise. After an experimental period of 3 or 10 days, the extensor digitorum longus, soleus and tibialis anterior muscles were studied. Dexamethasone treatment for 10 days reduced muscle weight and type IV collagen mRNA abundance in all muscles. Gene expression of matrix metalloproteinase-2 (MMP-2) was decreased in fast muscles. However, the effects of this decrease were possibly attenuated by the simultaneous decrease in the activity of tissue inhibitor of metalloproteinases (TIMP-2). The amount of type IV collagen was not changed during dexamethasone treatment or exercise. The regulation of type IV collagen degradation during dexamethasone treatment varied between slow and fast muscles. Although endurance running prevented muscle atrophy, exercise could not compensate the changes observed in the regulation of type IV collagen gene expression and degradation during dexamethasone treatment.
Ahtikoski
A M
AM
Department of Physiology, University of Oulu, Box 5000, 90014 Oulun Yliopisto, Finland. anne.ahtikoski@oulu.fi
Riso
E-M
EM
Koskinen
S O A
SO
Risteli
J
J
Takala
T E S
TE
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D015152:Blotting, Northern; D024141:Collagen Type IV / Q000235:genetics* / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D005938:Glucocorticoids / Q000494:pharmacology; D020778:Matrix Metalloproteinase 2 / Q000032:analysis / Q000235:genetics; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D024141:Collagen Type IV; D005938:Glucocorticoids; D012333:RNA, Messenger; D019716:Tissue Inhibitor of Metalloproteinase-2; D003907:Dexamethasone; D020778:Matrix Metalloproteinase 2