Precocene II (6,7-dimethoxy-2,2-dimethyl-2H-benzo[b]
pyran), an
insect growth regulator that is structurally related to several naturally occurring carcinogenic and non-carcinogenic alkenylbenzenes, is genotoxic and produces hepatic centrolobular
necrosis in rats. This investigation was conducted to evaluate the effects of modulation of hepatic
glutathione levels on the toxicity of
precocene II. Administration of a toxic dose of
precocene II (175 mg/kg) to male Sprague-Dawley rats rapidly depleted hepatic GSH, produced histopathological changes in the liver, and induced increases in serum
aminotransferase activity. Concurrent administration of the
cysteine pro-drug L-2-oxothiazolidine-4-carboxylic
acid (OTC) prevented these toxic effects of
precocene II. In contrast, pretreatment of rats with DL-
buthionine-SR-sulfoximine (BSO), an inhibitor of
glutathione synthesis, potentiated the toxicity of an otherwise non-toxic dose of
precocene II (100 mg/kg). These results indicate that
glutathione is important for protection from
precocene II-induced hepatotoxicity.