Chronic ethanol feeding increases apoptosis and cell proliferation in rat liver

The present study was conducted to evaluate if the increased rate of apoptosis previously reported in the liver of ethanol-treated rats was accompanied by increased cell renewal. A quantitative analysis of apoptosis was performed in rats fed an ethanol-containing liquid diet for 5 weeks. S-phase cells were demonstrated by immunohistochemistry, using the Bromodeoxyuridine/anti-Bromodeoxyuridine method. In ethanol-fed rats apoptosis was five times greater than in pair-fed controls. Bromodeoxyuridine-labelled hepatocytes increased from 0.07 +/- 0.009% in controls to 0.17 +/- 0.013% (p < 0.001) and Bromodeoxyuridine-labelled lipocytes (desmin-positive sinusoidal cells) increased from 3.43 +/- 0.28% to 6.60 +/- 1.04% (p < 0.001). The lobular distribution of labelled cells was modified with a shift towards the perivenular areas. The results of this study suggest that the replacement of liver cells lost by ethanol-induced apoptosis is not impaired in intact (non-operated) animals. The impaired regeneration following partial hepatectomy reported in ethanol-fed rats is possibly due to differences in the extent of parenchymal loss, to altered relationships between hepatocytes and blood supply and to the modalities of regeneration involved.