The present study made an attempt to measure the @entity701 content, as an indicator of stress response, in @entity5660 embryos which were exposed to different densities and handling stress (air exposure) during incubation. The three densities of experimental embryos at early development stages were considered as 2.55  embryos/cm(2) (low density), 5.10  embryos/cm(2) (normal density) and 7.65  embryos/cm(2) (high density). The @entity701 content of eggs (5.09      0.12  ng/g) decreased to 3.68      0.14  ng/g in newly fertilized eggs. Resting level of @entity701 dropped at three densities by day 18 of post fertilization. Then, @entity701 increased at hatching stage to 1.16      0.11, 1.20      0.12 and 1.21      0.14  ng/g at low, normal and high densities, respectively. There were no statistically significant differences between @entity701 concentrations in three densities. The acute handling stress test (5-min out-of-water), conducted on embryos (48  h post fertilization, organogenesis and eyed stage) in three densities, revealed no differences in whole-body @entity701 levels between stressed and unstressed experimental groups. At hatching stage in low-density group, level of @entity701 increased but the difference with the pre-stress levels was not statistically significant. Furthermore, significant differences in @entity701 levels of stressed and unstressed embryos were detected on hatching in normal and high density groups [1.20      0.12 at time 0-1.49      0.11  ng/g at 1  hps (hours post stress) and from 1.21      0.14 at time 0 to 1.53      0.10  ng/g at 3  hps, respectively]. The results showed no difference in profile of @entity701 in different densities, but acute stress conducted on embryos, incubated in different densities, revealed differences in @entity701 stress response at hatching between normal and high density, which lead to @entity701 increase at hatching time. It indicates that the lag time in the @entity701 response to stressors immediately after hatching does not occur when the siblings were stressed during the embryo stage. Results, finally, indicated that hypothalamus-pituitary-interrenal axis was active and responded to an acute stressor under normal and high density, but it is unresponsive to a stressor around hatching under low density.

The onset of stress response in XXXX @entity5660 embryos subjected to density and handling.

@entity5660 :: ('8022', 'Species') :: ['rainbow trout'] @entity701 :: ('MESH:D006854', 'Chemical') :: ['cortisol']
@entity5660 :: (8022,Species) :: ['rainbow trout']
