LEAD AND LIVER-CELL PROLIFERATION - EFFECT OF REPEATED ADMINISTRATIONS

Abstract

The effect of repeated treatments with Pb on hepatic cell proliferation was investigated in male Wistar rats. The animals were given i.v. injections of lead nitrate once every 10 days for 30 and 80 days. At the end of the experimental regimen, enlargement of the liver, accompanied by an increase in hepatic DNA content, was observed. A significant enhancement in the incorporation of labeled thymidine into hepatic DNA was found in Pb-treated rats when compared with controls. An increase in the number of liver cells involved in mitosis was also observed in Pb-treated animals. Analysis of serum glutamic-pyruvic transaminase and histologic observations did not show any sign of cell death. Liver cells exposed to repeated treatments with Pb underwent proliferation. A progressive reduction in the capacity of hepatic cells to divide was found in rats given repeated administrations of Pb, when compared with the extent of cell proliferation induced by a single dose of Pb nitrate.