Examination of the differential hepatotoxicity of diallyl phthalate in rats and mice

Identifying chemicals based on receptor binding/bioactivation/mechanistic explanation associated with potential to elicit hepatotoxicity and to support structure activity relationship-based read-across

The liver is the most common target organ in toxicology studies. The development of chemical structural alerts for identifying hepatotoxicity will play an important role in in silico model prediction and help strengthen the identification of analogs used in structure activity relationship (SAR)- based read-across. The aim of the current study is development of an SAR-based expert-system decision tree for screening of hepatotoxicants across a wide range of chemistry space and proposed modes of action for clustering of chemicals using defined core chemical categories based on receptor-binding or bioactivation. The decision tree is based on ∼ 1180 different chemicals that were reviewed for hepatotoxicity information. Knowledge of chemical receptor binding, metabolism and mechanistic information were used to group these chemicals into 16 different categories and 102 subcategories: four categories describe binders to 9 different receptors, 11 categories are associated with possible reactive metabolites (RMs) and there is one miscellaneous category. Each chemical subcategory has been associated with possible modes of action (MOAs) or similar key structural features. This decision tree can help to screen potential liver toxicants associated with core structural alerts of receptor binding and/or RMs and be used as a component of weight of evidence decisions based on SAR read-across, and to fill data gaps.

Rat hepatic mitochondria are more sensitive to allyl alcohol than are those of mice

The hepatotoxic effects of allyl alcohol with particular reference to mitochondrial morphology and function were compared in male CD1 mice and male CD rats 24 h after 0.05 ml/kg i.p. in corn oil. As already noted by others, allyl alcohol-treated rats usually showed histologic evidence of tissue necrosis when hematoxylin-eosin-stained tissue sections were examined whereas mouse tissue sections did not. The serum glutamic pyruvic transaminase (SGPT) activities were significantly elevated in both mice and rats but to a much greater extent in the latter. Pentobarbital sleeping time was significantly increased over that of corn oil control groups in rats but decreased in mice. In rats electron microscopy showed mitochondria which contained flocculent densities. State 4 respiration was not altered by allyl alcohol in rats, but state 3 respiration was significantly depressed indicating an absence of respiratory control and an inability to perform energy coupling. In allyl alcohol-treated mice the isolated mitochondria were found to be primarily in a condensed form. Except for the effect on pentobarbital sleeping time and SGPT, no other findings were different from those in control groups given only corn oil. When the dose of allyl alcohol in mice was increased to 0.15 ml/kg in an attempt to elicit more severe signs of hepatotoxicity, there was a high mortality in the first 24 h period without histologic evidence of liver necrosis. Thus, we confirm that at equivalent doses, male rats are more sensitive to the hepatotoxic effects of allyl alcohol than are male mice, and extend the generalization to the liver mitochondria of the 2 species.