Insulin-like growth factor-I (IGF-I) in serum and bone tissue during rat mandible fracture healing.

Insulin-like growth factor-I (IGF-I) is potent stimulator of proliferation and differentiation of osteoblasts, the biosynthesis of collagen type-I and noncollagenous proteins and alkaline phosphatase activity. The role of IGF-I in bone repair has not as yet been clearly defined. The aim of the present study was the quantitative analysis of IGF-I in the serum and tissue in four phases of fractured jaws healing in rat models. IGF-I concentrations in the serum and bone extracts were determined by RIA. In respect to the control group (K) the significant increase of IGF-I occurred in the serum in phase I (211 +/- 68 ng/ml, K-153 +/- 50 ng/ml) (p < 0.05). At the tissue levels a statistically significant increase in IGF-I was confirmed in phase II (262 +/- 60 ng/g, K-182 +/- 56 ng/g) (p < 0.05). The present results demonstrate that in rat models with fractured jaws in the first two phases of healing elevated levels of IGF-I in the serum and bone tissue were observed which indicate the significant role of this polypeptide in the early healing stages.