High copper and iron levels and expression of Mn-superoxide dismutase in mutant rats displaying hereditary hepatitis and hepatoma (LEC rats).

The LEC rat is a mutant strain displaying hereditary hepatitis and hepatoma. We established enzyme-linked immunosorbent assays of Cu,Zn- and Mn-superoxide dismutase (Cu,Zn- and Mn-SOD) and measured the levels of both SODs in various organs of LEC and Wistar rats. Mn-SOD concentrations were higher in LEC rats than in Wistar rats in most tissues. Cu,Zn-SOD levels of liver, kidney and intestine were lower in LEC rats than in Wistar rats. Atomic absorbtion techniques indicated that in addition to high Cu concentrations as previously reported, LEC rat livers contained high Fe concentrations relative to those in Wistar rat livers. These data suggest that increased concentrations of Fe and Cu and decreased levels of Cu,Zn-SOD may facilitate the Fenton reaction to produce hydroxyl radicals in the tissues of the LEC rat. To compensate for the decreased scavenging effects due to low levels of Cu,Zn-SOD, an adaptive increase of Mn-SOD may occur in the process of hepatitis and hepatocarcinogenesis in LEC rats.