Expression of insulin-like growth factor I messenger ribonucleic acid in regenerating bone after fracture: influence of indomethacin.
Expression of insulin-like growth factor I (IGF-I) was studied during time in the callus formed after tibial fracture in rats. Levels of IGF-I mRNA in callus peaked on the day 8 postfracture, showing a 10- to 15-fold induction compared to control bone. Levels of IGF-I mRNA tended also to be increased in the fracture-adjacent musculus tibialis anterior. IGF-I immunoreactivity was found in cartilaginous cells, osteoblasts, and myocytes 6 and 8 days after fracture. No obvious differences were found between hypophysectomized animals and control animals with regard to IGF-I immunoreactivity. Administration of the antiinflammatory drug indomethacin decreased the IGF-I mRNA expression in the tibial fracture model. Previous findings have shown that IGF-I is activated during in vivo muscle regeneration, and also in this model indomethacin administration reduces the expression of IGF-I. The finding that indomethacin administration reduces IGF-I expression could indicate that an inflammatory response may be important for activation of IGF-I during tissue regeneration.
Edwall
D
D
Center for Biotechnology, Novum, Karolinska Institute, Huddinge, Sweden.
Prisell
P T
PT
Levinovitz
A
A
Jennische
E
E
Norstedt
G
G
D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects*; D002146:Bony Callus / Q000378:metabolism; D007150:Immunohistochemistry; D007213:Indomethacin / Q000627:therapeutic use*; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008297:Male; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D013978:Tibial Fractures / Q000188:drug therapy*
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007213:Indomethacin