Changes of GH, IGF-I, RNA/DNA ratio and glycogen content of juvenile brown flounder during thermal stress and restoration

To investigate the changes of GH, IGF-I, RNA/DNA ratio and glycogen content of brown flounder (Paralichthys olivaceus) to thermal manipulation, we cultured the juveniles at 8.5 ℃(T8.5) , 13.0 ℃(T13.0) , 17.5 ℃(T17.5) , 22.0 ℃ (T22.0) and 26.5 ℃ (T26.5) for 10 d, and then adjusted to 22.0 ℃ for 30 d. The plasma IGF-I concentrationof T17.5 was lower than that of T22.0 during stressing period, but no significant difference was found in plasma GH and IGF-I concentration at different temperatures during stress and restoration periods. RNA/DNA ratios were significantly different in liver during 20~40 d but not significantly different in muscle during the whole experimental period. The glycogen contents in liver at T8.5, T13.0 and T26.5 were significantly lower than that at T17.5. At the end of the experiment, the glycogen contents in liverof T8.5, T13.0, T17.5 and T26.5 were slightly higher than thatof T22.0. The glycogen contents in muscle of T26.5 and of T13.0 were the highest at the end of stress period andon 20th day, repectively. The slow growth caused by 10-day culture at different temperatures could be completely compensated in 30 d after the temperature was adjusted to 22.0 ℃. No significant correlation was detected amongplasma GH, IGF-I concentration, RNA/DNA ratio and growth rate.