The proliferation of hepatocytes and the lipid composition of the endoplasmic reticulum after induction of drug-metabolizing enzymes with trans-stilbene oxide.

Three aspects of the induction of drug-metabolizing enzymes brought about by trans-stilbene oxide have been investigated. (1) The liver hypertrophy in rats treated with trans-stilbene oxide was found to result solely from an increase in the number of cells in this organ, without any increase in the size of each individual cell. (2) Administration of trans-stilbene oxide also produces a 27% increase in the phospholipid content of the hepatic endoplasmic reticulum, i.e., a limited proliferation of this organelle occurs. (3) Furthermore, induction causes changes in the lipid composition of the endoplasmic reticulum. The cholesterol content is decreased, the relative content of sphingo-myelin is also lowered, and a number of changes in the fatty-acid composition occur as well. All of these effects would tend to increase the fluidity of the phospholipid bilayer of the endoplasmic-reticulum membrane and may thus affect drug metabolism.