The experimental study on the effect calcitonin gene-related peptide on bone resorption mediated by interleukin-1

To investigate the effect of calcitonin gene-related peptide (CGRP) on bone resorption mediated by interleukin-1 beta(IL-1 beta) in vitro, the osteoclasts isolated from the long bones of newborn SD rats were co-cultured with osteoblasts on ivory slices placed in 24-well plates. 24 h later, conditioned media containing CGRP and/or IL-1 beta were added to the wells respectively, and continued culturing for 48 h. After the cells were stripped off by ultrasonication, the ivory slices were stained in toludine blue. The number and the total area of resorption lacunae on each slice were measured by computer imaging analysis system. Our results showed that IL-1 beta significantly stimulated bone resorption, but CGRP inhibited the effect mediated by IL-1 beta in a dose-dependent manner. It is suggested that CGRP may inhibit osteoclastic bone resorption through two ways: One is that CGRP functions directly on osteoclasts to block their activation; the other is that CGRP regulates the release of cytokines by osteoblasts and indirectly affects the function of osteoclasts.