Hepatic metallothionein and glutathione levels in Red Sea bream

The relationship between hepatic metallothionein (MT) and glutathione (GSH) in the Red Sea bream, Pagrus major , following treatment with cadmium (Cd), zinc (Zn), buthionine sulfoximine (BSO), and trans -stilbene oxide (TSO) was sought. Cd and Zn caused an increase in total GSH concentration and induced MT. BSO greatly decreased total GSH but apparently caused no synthesis of MT. TSO treatment resulted in a slight decrease in GSH concentration and a significant increase in MT. Pretreatment with BSO had no effect on MT synthesis caused by Cd, Zn and TSO. The total GSH level thus appears to be not directly involved in the regulation of MT concentration in Red Sea bream liver. MT induced by Cd, Zn and TSO was noted to have two isoforms. Their ratio when induced by Zn was different from that in the case of induction by Cd or TSO. The isoforms of MT may thus have different biological functions.