Glomerular sclerotic lesions in the rat. Histochemical analysis of their macromolecular and cellular composition

The present study provides a histochemical analysis of the macromolecular and cellular composition of focal and segmental glomerular hyalinosis and sclerosis (FSGHS) in the rat with special reference to the different types of lipids present and to the participation of monocytes. FSGHS was induced in male Wistar rats by unilateral nephrectomy (UN) or puromycin aminonucleoside (PAN) injections. Histochemical analysis of glomeruli with FSGHS in both models after 20 weeks of proteinuria revealed massive deposits of lipids. These lipid accumulations were shown to consist mainly of free and esterified cholesterol; triglycerides and phospholipids were present in small amounts. Monocytes, identified by the alpha-naphthyl acetate method for non-specific esterase activity were scanty in glomeruli affected by FSGHS with an average glomerular count of 0.1 in UN- and 0.2 in PAN-treated rats. When present, no preferential localization of monocytes in the lesions was observed. The progressive glomerular damage occurring once the process of hyalinosis and sclerosis has started may be related to the paucity of "scavenging" monocytes. Cholesterol may be one of the substances involved in the development of these glomerular changes.