Metallothionein expression and localization in rat bone tissue after cadmium injection

We investigated the induction of metallothionein (MT) by cadmium (Cd) in th e bone tissue of rats. To clarify the cell response to Cd in bone, the isof orm-specific expression of MT mRNAs (MT-I and MT-II) was examined by revers e transcriptase-polymerase chain reaction (RT-PCR). Both MT-I and MT-Il mRN A levels were increased within 3 h by Cd administration. MT (MT-I/MT-II) lo calization after single Cd injection were also confirmed by immunohistochem ical studies. Notably, MT-positive cells were time-dependently increased, a nd the positive cells were mainly localized in osteocytes. The cell-specifi c induction of MT may be associated with Cd accumulation and Cd-induced bon e injury in vivo. Furthermore, we also found that MT was consecutively expr essed in some osteoclasts of control rats. This finding suggested a new rol e of osteoclasts in bone metabolism. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.