Disposition and metabolism of ethylene glycol 2-ethylhexyl ether in Sprague Dawley rats, B6C3F1/N mice, and in vitro in rat hepatocytes.

Ethylene glycol 2-ethylhexyl ether (EGEHE) is a solvent used in a variety of applications.We report disposition and metabolism of EGEHE following a single gavage or dermal administration of 50, 150 or 500 mg/kg [14C]EGEHE in rats and mice and in vitro in rat hepatocytes.EGEHE was cleared rapidly in rat hepatocytes (half-life ∼4 min) with no sex difference.EGEHE was well- and moderately absorbed following oral administration (rats: 80-96%, mice: 91-95%) and dermal application (rats: 25-37%, mice: 22-24%), respectively, and rapidly excreted in urine.[14C]EGEHE-derived radioactivity was distributed to tissues (oral: 2.3-7.2%, dermal: 0.7-2.2%) with liver and kidney containing the highest levels in both species.EGEHE was extensively metabolised with little to no parent detected in urine. The alkoxyacetic acid metabolite, which has previously been shown to mediate toxicities of other shorter-chain ethylene glycol ethers, was not detected.There were no apparent dose, species or sex differences in disposition and metabolism of EGEHE, except that the exhaled volatile compounds were greater in mice (19-20%) compared with rats (<2%).These studies address a critical gap in the scientific literature and provide data that will inform future studies designed to evaluate toxicity of EGEHE.

Proteomic analysis of liver proteins of mice exposed to 1,2-dichloropropane.

1,2-Dichloropropane (1,2-DCP) is recognized as the causative agent for cholangiocarcinoma among offset color proof-printing workers in Japan. The aim of the present study was to characterize the molecular mechanisms of 1,2-DCP-induced hepatotoxic effects by proteomic analysis. We analyzed quantitatively the differential expression of proteins in the mouse liver and investigated the role of P450 in mediating the effects of 1,2-DCP. Male C57BL/6JJcl mice were exposed to 0, 50, 250, or 1250 ppm 1,2-DCP and treated with either 1-aminobenzotriazole (1-ABT), a nonselective P450 inhibitor, or saline, for 8 h/day for 4 weeks. Two-dimensional difference in gel electrophoresis (2D-DIGE) combined with matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF/MS) was used to detect and identify proteins affected by the treatment. PANTHER overrepresentation test on the identified proteins was conducted. 2D-DIGE detected 61 spots with significantly different intensity between 0 and 250 ppm 1,2-DCP groups. Among them, 25 spots were identified by MALDI-TOF/TOF/MS. Linear regression analysis showed significant trend with 1,2-DCP level in 17 proteins in mice co-treated with 1-ABT. 1-ABT mitigated the differential expression of these proteins. The gene ontology enrichment analysis showed overrepresentation of proteins functionally related to nickel cation binding, carboxylic ester hydrolase activity, and catalytic activity. The results demonstrated that exposure to 1,2-DCP altered the expression of proteins related with catalytic and carboxylic ester hydrolase activities, and that such effect was mediated by P450 enzymatic activity.

Exposure of Mice to 1,2-Dichloropropane Induces CYP450-Dependent Proliferation and Apoptosis of Cholangiocytes.

1,2-Dichloropropane (1,2-DCP) has been used as a paint remover in the industry. The International Agency for Research on Cancer reclassified this compound recently to group 1 (carcinogenic to humans) based on epidemiological studies of cholangiocarcinoma among offset-color proof-printing workers exposed to 1,2-DCP in Japan. Two-year rodent carcinogenicity bioassays demonstrated that 1,2-DCP induced tumors in liver and lung, but not in bile duct. The present study was designed to assess the toxic effects of 1,2-DCP on proliferation and apoptosis in mice bile duct and the role of cytochrome P450 (CYP450) in any such effect. Male C57BL/6JJcl mice were cotreated or untreated with 1-aminobenzotriazole (1-ABT), a CYP450 inhibitor, and exposed to inhalation of 1,2-DCP at 0, 50, or 250 ppm alone, or at 0, 50, 250, or 1250 ppm 8 h/day for 4 weeks. Exposure to 1,2-DCP increased proliferation and apoptosis of cholangiocytes and induced severe hepatic damage, but had no effect on the lungs. Cotreatment with 1-ABT abrogated the effects of 1,2-DCP on proliferation and apoptosis of cholangiocytes. The results revealed that 1,2-DCP induces proliferation and apoptosis of cholangiocytes and that this effect is mediated through CYP450.