Biological responses of xenobiotic metabolizing enzymes to lead exposure in cultured H4IIE rat cells.

This study was undertaken to investigate the constitutive response of xenobiotic metabolizing enzymes (XMEs) to lead (Pb2+) exposure in cultured rat liver (H4IIE) cell lines. Phase I enzymes such as CYP1A1 and CYP1A2 had mRNA expressions that were slightly induced after exposure to low concentrations of Pb2+; however, under higher concentrations of Pb2+, the mRNA expressions of CYP1A1 and CYP1A2 were significantly down-regulated. These effects were in correspondence with AhR mRNA expression. Phase II enzymes had mRNA expressions that were reduced upon exposure to Pb2+. Metallothionein mRNA expression was induced after treatment with Pb2+ in a dose-dependent trend. In conclusion, Phase I and II enzymes were significantly modulated upon lead exposure indicating some toxicological implications for lead exposure in cultured H4IIE cells.