Abstract:

ABSTRACT Objective: To build a model to observe the characteristics of renal injury in rats by exposure to xylene. Methodology: Male Sprague-Dawley rats (n=57), weighing 140-160g, 4-6 week old, were used in this study. They were randomly divided into two groups: control group (n=7) and xylene exposure group (n=50), who were exposed to xylene six hours per day for twelve weeks. The 24h urinary protein excretion and urinary NAG levels were measured. In addition, serum total protein (TP), albumin (Alb), urea (BUN), creatinine (Scr), aspartate amino transferase (AST) and alanine amino transferase (ALT) levels were examined. The tubular and glomerular morphology were observed by light microscopy and transmission electronmicroscopy. The podocin and synaptopodin expression and distribution change were determined by indirect immunofluorescence staining. Results: Compared with the control rats, the proteinuria was observed in rats after xylene exposure of 3 weeks, and the amount of urinary protein excretion was increased to 34.78±2.91mg/24h at 8 weeks. The level of urinary NAG was increased obviously after the xylene exposure of 4weeks. After xylene exposure of 12 weeks, the urinary NAG in experiment and control rats was 25.03±4.88 u/gScr and 14.36±2.05 u/gScr, respectively. No significant differences were found in the levels of TP, Alb, Scr and ALT. The levels of serum urea was increased in xylene exposed rats at 12 weeks (P＜0.05) and AST was increased significantly. The histological examination by microscopy showed that there were remarkable injuries in proximal renal tubule, including loss of brush border and vacuolar degeneration of the epithelial cells. Ultra structural study demonstrated that brush border and cytoplasm of tubular epithelial cell were dropped and some epithelial cells were disintegrated. The mitochondria of tubular epithelial cells was swollen and the electron density was decreased in matrix. The results by immunofluorescence staining showed that distribution of podocin and synaptopodin along GBM was discontinuous and granular after xylene exposure of 12 weeks. Conclusion: The present study indicates the renal injury by exposure to xylene. The severity of tubular epithelial cell damage was significantly heavier than that of podocytes.

Key words: xylene, rats, proteinuria, tubule, glomerulus