Studies on the subchronic nephrotoxic potential of styrene in Sprague-Dawley rats

The nephrotoxic potential low non-toxic dose of styrene was studied in male Sprague-Dawley rats. Groups of rats received i.p. injections of styrene in corn oil at doses 0, 2.9, and 5.8 mmol/kg once daily, 5 days/week for 6 consecutive weeks. After collection of urine for 0-24 and 24-48 h following the end of the treatment, the rats were sacrificed. A significant increase in the excreted urinary volume was noticed at 5.8 mmol styrene during 0-24 and 24-48 h, relative to control, whereas urinary concentrations of gamma-glutamyl transpeptidase and glucose were significantly elevated during the 24-48-h period. Urinary activity of N-acetyl-beta-D-glucosaminidase was increased at the higher dose of styrene during 0-24 and 24-48 h. The capacity of renal cortical slices to accumulate p-aminohippurate was significantly reduced 48 h after the exposure to any dose of styrene. Electron microscopic examination of renal cortex 48 h after the exposure to a higher dose revealed the presence of enlarged mitochondria having more electron dense matrix. The data suggest that subchronic exposure to a very low non-toxic dose of styrene may have the potential to elicit nephrotoxicity preferentially in the proximal tubular region of the rat kidney.