Light ethanol consumption enhances liver regeneration after partial hepatectomy in rats

Background & Aims: The effects of "social drinking" on the liver have yet to be fully documented. The aim of this study was to document the effects of daily light, moderate, and heavy ethanol exposure on hepatic regenerative activity in the rat. Methods: Adult male Sprague-Dawley rats underwent daily gavages with 1.0 (light), 2.0 (moderate), or 4.0 (heavy) g/kg of ethanol or tap water (controls) for 30 days before 70% partial hepatectomy (PHx). Hepatic regenerative activity was then documented on days 1, 3, 5, and 7 after PHx. Results: Compared with controls, restitution of liver mass, [H-3]thymidine incorporation, and proliferating cell nuclear antigen expression were decreased in the heavy (-10%, -60%, and -36%, respectively), unchanged in the moderate (-4%, -8%, and -16%, respectively), and increased in the light (+6%, +38%, and +29%, respectively) ethanol groups. Messenger RNA differential display of resected livers at PHx identified a band present only in the light ethanol group that encodes a unique 47-kilodalton protein with growth-promoting features designated light ethanol-induced stimulatory protein. Conclusions: The results indicate that light ethanol consumption enhances hepatic regenerative activity after PHx in rats. Further studies are required to determine the mechanism involved and whether social drinking has beneficial or adverse effects on the natural history of acute or chronic liver disease in humans.