Histology and histopathology Vol. 4, nº 1 (1989)

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Effects of 4-aminopyrazolo (3,4-d) pyrimidine on rat hepatocytes: an ultrastructural morphometric study
(Murcia : F. Hernández, 1989) Belloni, A. S.; Rebuffat, P.; Mazzocchi, G.; Meneghelli, V.; Nussdorfer, G.G.
Summary. The prolonged administration of the hypolipidemic drug 4-aminopyrazolo (3,4-d) pyrimidine (4APP) induced conspicuous morphological changes in rat hepatocytes, which are clearly demonstrated by stereology. We observed a significant decrease in the rough endoplamic reticulum, and an accumulation of lipid droplets, which was coupled with a comparable rise in the hepatic concentrations of total cholesterol and triglycerides. These changes were interpreted as the expression of the 4APP-provoked impairment of the synthesis of the polypeptide chains of lipoproteins and of the consequent suppression of the assembly of lipid molecules in exportable lipoproteins. We also noted a neto lowering in smooth endoplasmic reticulum and perxisomes, a decrease which was hypothesized to be the morphological counterpart of a reduced de novo cholesterol synthesis, due to the 4APP-induced rise in the intracellular cholesterol concentration.