Local and systemic expression of insulin-like growth factor-I (IGF-I) mRNAs in rat after bone marrow ablation.
Local and systemic expression of insulin-like growth factor-I (IGF-I) during bone formation was studied using the rat bone marrow ablation model. The temporal expression pattern of IGF-I mRNA in rat femurs was examined. The IGF-I mRNA level was enhanced rapidly after ablation reaching a level threefold greater than basal by day 3 (P < 0.01) and declined to basal or below basal level by day 5. Histological analysis showed that IGF- I immunoreactivity was predominantly associated with the mesenchymal cells at the bone/connective tissue interface and osteoblastic cells at active sites of bone formation. Serum level of IGF-I increased 50 and 130%, respectively (P < 0.005), over the basal level at days 3 and 6. We also investigated the systemic expression of IGF-I in liver and kidney. In contrast, hepatic IGF-I gene expression decreased 37 and 48%, respectively, at days 3 and 6 after marrow ablation (P < 0.001). Kidney IGF-I mRNA levels also fell 13 and 27%, respectively, at days 3 and 6 (P < 0.005). The present findings suggest that locally produced IGF-I during bone formation may not only serve as an autocrine/paracrine factor but also influence systemic expression of IGF-I in other organs.
Tanaka
H
H
Department of Orthopedic Surgery, Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan. htanaka@po.cc.yamaguchi-u.ac.jp
Wakisaka
A
A
Ogasa
H
H
Kawai
S
S
Liang
C T
CT
D000818:Animals; D001769:Blood / Q000378:metabolism; D001853:Bone Marrow / Q000378:metabolism* / Q000601:surgery; D005246:Feedback; D005269:Femur / Q000378:metabolism / Q000601:surgery; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000302:isolation & purification; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D010012:Osteogenesis / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D007334:Insulin-Like Growth Factor I