SEXUAL DIMORPHISM IN THE REACTION OF ZEBRAFISH (BRACHYDANIO-RERIO) TOASCORBIC-ACID DEFICIENCY - INDUCTION OF STEATOSIS IN HEPATOCYTES OF MALE FISH

Zebrafish (Brachydanio rerio) fed diets free of ascorbic acid (vitamin C) or supplemented with 200 mg/kg ascorbic acid for 12 weeks were com pared with respect to macroscopically detectable symptoms of pathology and cytological alterations of hepatocytes. Fish fed the ascorbic aci d-free diet displayed symptoms of scurvy including hemorrhages, fin er osion, and darker pigmentation. Hepatocytes of male zebrafish develope d steatosis, whereas liver cells of female zebrafish were free of micr ovesicular lipid accumulation within the endoplasmic reticulum cistern ae, indicating the presence of sex-dependent protection mechanisms aga inst ascorbic acid depletion. Female fish showed a reduction of hepato cellular size and a less regular arrangement of the rough endoplasmic reticulum; hepatocellular glycogen depletion as well as induction of s mooth endoplasmic reticulum were characteristic of hepatocytes in eith er sex. Since zebrafish fed the diet supplemented with ascorbic acid w ere free of pathological alterations in both external appearance and h epatocellular ultrastructure, results indicate that ascorbic acid not only plays a key role in collagen biosynthesis, but also fulfills cent ral functions in the maintenance of a well-equilibrated lipid metaboli sm in fish. Accumulation of oxidative reagents represents one possible mechanism leading to hepatocellular steatosis in fish.