Profile of cortisol changes during early stages of development in rainbow trout
Gholam Reza Ghaedi1, Vahid Yavari1, Bahram Falahatkar2, Amir Parviz Salati1 & Reza Sahraeian1
Whole-body cortisol content was measured in oocyte, embryo and larvae of rainbow trout by extraction and RIA. The cortisol content of oocyte was 2.55±0.06 ng/ml that probably has a mathernal origin. After fertilization cortisol level decreased to 1.84±0.07 ng/ml, then reached to the lowest level (0.30±0.06 ng/ml) by day 10 where it remained unchanged until eyed stage on day 18. After that cortisol increased at hatching to 0.60±0.06 ng/ml, suggested that cortisol biosynthesis was occurred. Cortisol level was increased to 3.01±0.14 at 2-week-old fish. Result of this study showed that cortisol biosynthesis could be observed in rainbow trout during the late stages of embryo development, before hatching will be started.