The effect of food deprivation and refeeding on the liver, thyroid hormones and transthyretin in sea bream

There was a significant reduction in body weight of sea bream Sparus aurata and the hepatosomatic index after 3 weeks food deprivation. Liver biochemi cal indices and morphology were altered by food deprivation, there was a lo ss of eosin staining in hepatocyte cytoplasm and the appearance of large de pleted vacuoles. Cell and nuclear area were significantly reduced (P<0.001) and did not return to control values after 1 week of refeeding. The water. lipid, glycogen and protein content of the liver was significantly reduced by 3 weeks fasting but recovered rapidly after 1 week refeeding. Food rest riction also had a marked effect on circulating thyroid hormones and the co ncentration of plasma T-3 (33.98 +/- 12.47 ng ml(-1)) and T-4 (16.54 +/- 9. 5 ng ml(-1)) was significantly (P<0.001) lower than the control (66.52 +/- 13.4 and 56.83 +/- 7.3, respectively). Refeeding for 1 week restored circul ating T-3 (P<0.05) close to control levels but did not significantly affect the concentration of T-4. Northern blotting with an homologous probe for t ransthyretin (TTR) demonstrated clearly the expression of a single mRNA tra nscript of 0.7 kb for this protein in the liver. The level of TTR message w as substantially reduced below control levels in the liver of fasted fish a nd 1 week refeeding failed to restore expression. (C) 2000 The Fisheries So ciety of the British Isles.