Experimentally induced lipidosis in rat retinal pigment epithelium. A brief review.

Chronic administration of certain cationic amphiphilic drugs to rats and other species induces generalized lysosomal storage of polar lipids. In rat, retinal pigment epithelium belongs to the tissues which are most susceptible toward this adverse drug action. Drug-induced lipidosis in retinal epithelium is characterized ultrastructurally by the occurrence of numerous cytoplasmic inclusion bodies with a crystalline-like internal structure. Freeze-fracture images of such inclusions indicate that they consist of phospholipids aggregated in a hexagonal phase. The quantitative and structural uniformity of lipidosis in retinal pigment epithelial cells appears to reflect the uniformity of the lipid load which is physiologically imposed on the digestive apparatus of the epithelium due to the phagocytosis of photoreceptor membranes. The pathophysiological significance of drug-induced lipidosis in pigment epithelium remains to be clarified.