Changes in liver enzyme activity in the teleost Sparus aurata in response to cadmium intoxication

Enzyme activity modulation by cadmium in the liver of the teleost fish Spar us aurata was investigated in vivo following 3 and 6 days of CdCl2 administ ration (2.5 mg/kg body wt). The specific activities of the mitochondrial en zymes NAD-isocitrate dehydrogenase, succinate dehydrogenase, and malate deh ydrogenase were stimulated by approximately 20% after 3 days administration and were further increased (by about 40%) after 6 days treatment. In compa rison with these enzymes, the activities of glutamate-oxaloacetate transami nase (GOT) and glutamate-pyruvate transaminase (GPT) in mitochondria were l ess stimulated after the two indicated intervals of treatment. Cadmium sign ificantly reduced the activities of liver cytoplasmic GOT and GPT while a s imultaneous increase occurred in the serum activities of these same enzymes . The activity of liver NADPH-cytochrome P450 reductase was stimulated by 2 5 and 40% after 3 and 6 days cadmium intoxication, respectively. Lastly, th e antioxidant enzymes glutathione peroxidase and glutathione reductase in l iver and catalase in both liver and blood were strongly reduced after 3 and 6 days cadmium administration. These data suggest that cadmium in fish hep atocytes alters cell membrane structure and concomitantly induces some pert urbation in the integrity of the mitochondrial membrane. (C) 1999 Academic Press.