Hepatic peroxisomal changes induced by a tetrazole-substituted alkoxyacetophenone in rats and comparison with other species.

Previous work in this laboratory indicated that compound LY171883, a tetrazole-substituted alkoxyacetophenone with leukotriene D4 antagonist activity, caused dose-related hepatomegaly in rodents without other histological evidence of liver toxicity. In the present studies, administration of LY171883 at dietary concentrations of 0.25 or 0.50% to rats for 2 weeks increased peroxisomal beta-oxidation, catalase activity, and peroxisome volume fraction in the liver. The effects were dose-related and corresponded with increases in liver weight. Dietary concentrations of 0.05 and 0.1% LY171883 did not significantly alter peroxisome morphology, enzyme activity, or liver weight. Serum triglycerides were lowered equivalently by all four dietary concentrations of LY171883, indicating that the hypotriglyceridemia was dissociated from induction of peroxisomal beta-oxidation. The hepatic effects in rats reversed within 16 days after discontinuing treatment with LY171883. Liver weight and peroxisomal enzyme activities were increased in mice by LY171883 in a manner comparable to that observed in rats, whereas hamsters were less responsive. In guinea pigs there was a minor increase in beta-oxidation at a toxic dose of LY171883, but no change in catalase or liver weight. Neither hepatomegaly nor induction of peroxisomal enzymes occurred in beagle dogs or rhesus monkeys given LY171883. Since the hepatic effects of LY171883 in rats are not observed in higher species at a significant multiple of the anticipated clinical dose, it is unlikely that such effects will occur in humans.