Hepatic effects of orally administered styrene in rats.

Adult male rats receiving styrene by gavage (200 or 400 mg kg−1, 6 days a week) for 100 days exhibited a significant dose-dependent increase in hepatic benzo[a]pyrene hydroxylase and ammopyrine-N-demethylase, a decrease in glutathione-S-transferase and no change in glucose-6-phosphatase. A decrease in the activity of mitochondrial succinic dehydrogenase and β-glucuronidase was also observed. Activity of acid phosphatase was decreased only at the higher dose level. Levels of serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase were elevated only at the higher dose level. The absolute and relative weights of the liver of control and treated animals showed no significant difference. Histopathological studies of the liver tissue revealed tiny areas of focal necrosis, consisting of few degenerated hepatocytes and inflammatory cells at the higher dose level only.