Effect of cadmium on hepatic mixed-function oxidases during the early development of rats : possible protective role of metallothionein

Abstract

Hepatic metallothionein contents and activities of mixed function oxidases in control and cadmium-treated rats (1.2 mg Cd²⁺/kg) of various age groups (7-, 14-, 21- and 90-days-old) were determined. A significantly high concentration of native metallothionein was noticed in immature rats (7- and 14-days-old). Cadmium administration induced metallothionein only in 21- and 90-day-old rats, while the basal level of native metallothionein of immature rats was not altered. Activity of certain mixed-function oxidases (MFO) such as aryl hydrocarbon hydroxylase, aminopyrine-N-demethylase, and benzphetamine-N-demethylase was inhibited significantly only in 21- and 90-day-old rats. Microsomal cadmium accumulation was significantly higher in adult as compared to immature rats. Results suggest a protective role of metallothionein against cadmium-induced inhibition of mixed-function oxidases in immature rats.