Gene expression of insulin-like growth factor-I and IGF-I receptor during wound healing in rats.

ABSTRACT

OBJECTIVE: To measure the time course of changes in the concentrations of insulin-like growth factor-I (IGF-I), IGF-I messenger RNA (mRNA), and IGF-I receptor mRNA during wound healing. DESIGN: Open experimental study. MATERIAL: 40 male Sprague-Dawley rats, each weighing 300 g. INTERVENTION Stainless steel wire mesh cylinders implanted in the subcutaneous tissue of the back. Five rats killed at each time point (1.5, 2, 3, 4, 5, 7, 11, and 18 weeks). MAIN OUTCOME MEASURES: Wet weight and concentrations of IGF-I mRNA, and IGF-I receptor mRNA of granulation tissue, and concentration of IGF-I in wound fluid. RESULTS: The wet weight of granulation tissue increased significantly between week 1.5 and weeks 4-5, and then decreased. IGF-I mRNA concentration (amol/microgram DNA) increased significantly (threefold) between week 1.5 and weeks 3-5, and decreased between weeks 5 and 7. The concentration of IGF-I receptor RNA remained constant throughout the study, and the concentration of IGF-I in wound fluid remained constant until week 8 and then increased to a higher level at weeks 11-18. CONCLUSION: There is a transient rise in the gene expression of IGF-I but not of IGF-I receptor mRNA during wound healing.