ELEVATED ORNITHINE DECARBOXYLASE ACTIVITY IN WINTER FLOUNDER LIVERS EXHIBITING CELLULAR LESIONS

The activity of ornithine decarboxylase (ODC), the primary enzyme responsible for polyamine biosynthesis in animals, is often elevated in proliferative and abnormal growth situations. In this study, ODC was utilized as a biochemical indicator for cell proliferation to characterize proliferative hepatic lesions in 24 Boston Harbor winter flounder (Pleuronectes americanus). Cellular vacuolation, the commonest epithelial change defining disease, was present in 12/24 fish. ODC activity (nmol/mg protein/h at 37-degrees-C) was significantly elevated in livers exhibiting cellular vacuolation (4.20 +/- 1.08 SE) compared with non-vacuolated livers (0-33 +/- 0.13 SE, p = 0.002). Sex and spawning status had no significant affect on ODC activity. ODC activities within foci of cellular vacuolation were as high or higher than surrounding parenchyma. These results demonstrate elevated ODC activity in diseased winter flounder livers and suggest that cellular proliferation may be an important part of this disease process. Analysis of ODC activity in specific cell types will further our understanding of hepatocarcinogenesis in winter flounder.