Induction of metallothionein mRNA expression in the mouse liver after cadmium injection as measured by the reverse transcriptase-polymerase chain reaction method

Metallothioneins (MTs) are low molecular weight proteins that have been con sidered to be important metal-binding proteins in the defense against cadmi um (Cd) toxicity in animals. Thee proteins are known to be induced by the i njection of heavy metals such as Cd. Previously, we developed the RT-PCR me thod to measure the level of MT mRNA expression. In this study, we analyzed the time course and dose response of Cd-induced MT-I mRNA expression in th e male and female mouse liver. By this method, we measured hepatic MT-I mRN A expression which reached the highest peak 6 h after subcutaneous injectio n of 1.1 mg/kg Cd in 9-week old male and female mice compared wit those of corresponding controls (0 h). There was no statistical difference in the he patic MT-I mRNA expression between male and female mice 6 h after the injec tion of this dosage. However, it is notable that the MT-I mRNA expression i n male mice was much higher than that in females 6 h after injection of 0.5 mg/kg Cd. Thus, the induction of hepatic MT-I mRNA expression is dependent on the sex of the mouse, the dosage and the time course of Cd. (C) 2000 Pr ous Science. All rights reserved.