Induction of insulin-like growth factor I messenger ribonucleic acid during regeneration of rat skeletal muscle.
Expression of insulin-like growth factor I (IGF-I) was studied in regenerating skeletal muscle. Irreversible damage to muscle cells was induced in the extensor digitorum longus muscle of adult rats by ischemia, preceded by glycogen depletion. IGF-I mRNA levels during the regeneration process were studied for periods up to 10 days after injury using a solution hybridization assay. Increased IGF-I mRNA levels could be demonstrated within 24 h after injury; maximum levels were achieved in 3 days and decreased to approximately normal levels by 10 days. Changes in IGF-I mRNA levels could not be seen in undamaged contralateral extensor digitorum longus muscles during the experimental period. An increase in IGF-I mRNA was also evident in injured muscles of hypophysectomized animals. In situ hybridization at the time of maximum induction showed the presence of IGF-I mRNA in proliferating myoblasts and in satellite cells. IGF-I, thus, may act as a locally produced non-GH dependent trophic factor during regeneration of skeletal muscle after injury.
Edwall
D
D
Karolinska Institute, Huddinge University Hospital, Sweden.
Schalling
M
M
Jennische
E
E
Norstedt
G
G
D000818:Animals; D015152:Blotting, Northern; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007511:Ischemia / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000098:blood supply / Q000502:physiology*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012038:Regeneration; D013002:Somatomedins / Q000235:genetics*
D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I