A study on experimental focal glomerular sclerosis in rats: significance of intraglomerular lipid deposition

The present study deals with intraglomerular lipid deposition and its relation to the development of focal glomerular sclerosis (FGS) in rats. Experimental FGS was induced by repeated administration of puromycin aminonucleoside (AN) and was observed from the 3rd to 6th month. At 3 months after the beginning of the experiment, FGS lesions, marked proteinuria and hyperlipidemia were observed. Sudan III-stained sections revealed intraglomerular deposition of lipid, especially in the sclerotic lesions. An immunofluorescent study demonstrated nodular or massive deposition of IgM, IgG and fibrinogen in the sclerotic areas. Significant positive correlation was observed between the degree of intraglomerular lipid deposition and glomerular damage. In order to examine the intraglomerular lipid, isolated glomeruli which were obtained by a sieving method were analyzed by thin layer chromatography. The intraglomerular lipid consisted of cholesterol ester with a small amount of triglyceride. The incidence of sclerosis and excretion of urinary protein attained peak levels at the 3rd month and then decreased, but hyperlipidemia was prolonged. It is suggested that hyperlipidemia and intraglomerular lipid deposition may contribute to the development of FGS in aminonucleoside nephrosis.