Changes in Metallothionein Isoform Expression in the Bones of Ovariectomized Rats

Metal-binding proteins, metallothioneins (MTs), may play important roles in bone metabolism. However, the contribution of MTs to bone metabolism remains obscure. In the present study, we investigated the expression of MT isoforms in bone cells and mRNA for MT isoforms in the tibiae following ovariectomy (OVX). The results obtained showed that MT-I/II and MT-III were expressed in osteoblasts, osteoclasts, and osteocytes 4 weeks after OVX. Peaks in the mRNA expression ratios (OVX/Sham) of MT-I/II and MT-III changed following OVX. The expression ratio of MT-I/II increased after 1 week, whereas that of MT-III increased 4 weeks after OVX. These results suggest that the contribution of MTs to bone metabolism may depend on the isoforms in the cell types and the stage after OVX.