Toxicological significance of hepatic responses to furylfuramide(AF-2) in the rat.

In male rats fed furylfuramide [2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide, AF-2] at a dietary level of 0.1%, a marked increase in the liver weight was observed with a concomitant reduction of microsomal mixed function oxidase activity. To clarify the significance of these hepatic responses to furylfuramide, a series of biochemical parameters that reflect hepatotoxicity was measured. The most significant elevations were seen in hepatic glycogen and glucose 6-phosphate dehydrogenase levels over 29-day feeding interval. A marked decrease was observed in mixed-function oxidases and glucose 6-phosphatase activities. Moderate decreases were seen in several other parameters, especially in the early phase of feeding. Measurement of serum parameters showed significant elevation in cholesterol and a transient increase in serum glutamic pyruvic transaminase. A comparative study demonstrated small differences between furylfuramide and carbon tetrachloride in their effects on hepatic parameters. The furylfuramide-induced changes appear to be reversible within 14 days after withdrawal of furylfuramide from the diet. Reduction of mixed-function oxidase activity by furylfuramide might be caused partly by the elevation of heme degrading enzyme. The results indicate a dysfunction of drug-metabolizing activity and acute and slight toxication of the liver by furylfuramide.