Arsenic induces and enhances rat hepatic metallothionein production in vivo

Abstract

Metallothionein genes (MT) are inducible by a variety of agents, including heavy metals. We report the induction of MT expression by arsenite (As 3+) in rat liver in vivo. As 3+ (but not arsenate [As 5+]) injection increased MT protein and MT-1 and MT-2 mRNA accumulation in liver only, but not in kidney or pancreas. In addition, As 3+ enhanced zinc-induced MT protein accumulation in liver without any increase in MT mRNA levels. These data indicate that arsenic may increase MT expression either directly (by inducing MT mRNA accumulation), or indirectly by altering post-transcriptional events. This constitutes an unusual mechanism of enhancement of MT gene expression and appears to be mediated by processes not specifically associated with binding of arsenite to MT in vivo.