SEVERE OXIDATIVE STRESS IS THOUGHT TO BE A PRINCIPAL CAUSE OF JAUNDICE OF YELLOWTAIL SERIOLA-QUINQUERADIATA

The jaundiced yellowtail Seriola quinqueradiata had yellow discolored skin and hyperbilirubinemia, Histology revealed that hemosiderin and c eroid occurred in the spleen. In the vascular system, there were vascu litis and sinusoidal dilatation. Hepatic cells showed degenerative fig ures with pyknotic or karyolytic nuclei, basophilic cytoplasm, cytopla smic vacuoles in various sizes, and ceroidosis. In the bile duct syste m, however, there was no noticeable change. Hemoglobin contents of jau ndiced fish were similar to those of control fish. Plasma taurine leve ls of jaundiced fish were significantly lower than those of control (p <0.05). Judging from 2-thiobarbituric acid reactive substance values, in vivo lipid peroxidation progressed in the liver of jaundiced fish. In the plasma of jaundiced fish, contents of unconjugated bilirubin we re significantly higher than those of conjugated bilirubin. A large am ount of substance Xs, breakdown products of bilirubin scavenging activ e oxygen species, existed in the plasma of jaundiced fish. Therefore, jaundiced fish may suffer from severe oxidative stress, which might be a principal cause of jaundice. Liver superoxide dismutase and glutath ione peroxidase activities of jaundiced yellowtail were significantly lower than those of controls. (C) 1998 Published by Elsevier Science B .V.