Regression mechanism of cyanamide-induced inclusion bodies in the rat: a useful experimental pattern to study the beta-glycogen metabolization of hepatocytes.

Cyanamide, a drug used in alcohol aversion therapy, induces a distinctive liver cell lesion, both in human beings and rats. The lesion consists of cytoplasmic inclusion bodies which give a ground-glass appearance to the hepatocytes. In human beings the inclusion bodies do not persist but disappear some time after withdrawal of the drug. In order to confirm their disappearance and determine how they regress rats were treated with cyanamide (32 mg/kg) for 6 months before partial lobectomy. At this time, inclusion bodies were observed. After a period without further treatment (5-19 weeks) the animals were killed and a marked decrease in the number of inclusion bodies was observed, paralleling the period of time without treatment. Inclusion bodies regress as a result of glycogen removal by enzymatic activity of the smooth endoplasmic reticulum which then undergoes hyperplasia, plus a process of autophagocytosis and necrosis of inclusion-body-bearing hepatocytes which are then phagocytosed by macrophages.