Microvesicular fatty liver in rats with resembling Reye's syndrome induced by 4-pentenoic acid.

To produce an animal model of Reye's syndrome (RS), 20 adult male Wistar rats were given 10 repeated i.p. injections of 50 mg/kg 4-pentenoic acid (PA) each separated by an 8-h interval. Then, 90 min after the tenth dose, they were given a final i.p. injection of 150 mg/kg PA. Thirteen control animals were injected with vehicle only using the same time schedule. More than half the animals in each group were fed a common diet, but the others were fasted during the terminal 10-h stage. All rats were sacrificed 30 min after the last injection. At the terminal stage, in comparison with the vehicle-injected controls, hypolipemia, hypoglycemia and high titers of serum ammonia and urea N were estimated significantly in the PA-treated rats fed throughout the whole period. Hypolipemia and hypoglycemia were more prominent in the terminally fasted group than the group fed continuously. Only in the PA-treated rats fed throughout the whole period moderate morphological signs of microvesicular fatty liver were exhibited. Ultracytochemical findings and biochemical determinations showed that the major lipids in the microvesicular fatty livers were triglycerides. Morphometric analysis revealed distinct hepatic mitochondrial swelling in the PA-treated rats. Therefore, the above treatment with PA was able to induce microvesicular fatty liver in rats with resembling RS, which were fed throughout the treatment procedure, but not in the terminally fasted rats.