[Effects of mechanical strain on the proliferation and expression of IGF-1 mRNA in rat osteoblasts]

With the use of a cyclic strain unit, the proliferation and gene expression of IGF-1 in the rat osteoblasts that underwent mechanical strain were studied. The cells were subjected to 15% elongation at frequency 20 cycles/min for different loading time. Under the action of different loading time, the relative proliferation index of the rat osteoblasts was the biggest of all when loading time was 12h; during the course, the expression of IGF-1 mRNA increased significantly, and then gradually tended toward 1 with the increase of the loading time. These results demonstrate that osteoblasts respond to the mechanical forces which may regulate the activities of osteoblasts indirectly by promoting the autocrine effect of IGF-1. Loaded osteoblasts can adjust and adapt themselves to new mechanical stimulation, and hence maintain a new state of equilibrium.