Differential stress coping in wild and domesticated sea trout

Offspring of wild and sea-ranched [domesticated) sea trout (Salmo trutta) o riginating from the same river, were reared under identical hatchery condit ions from the time of fertilization. At one year of age individual fish wer e exposed to two standardized stressors; transfer to a novel environment, w ith or without a simultaneous predator exposure. Blood plasma concentration s of glucose and cortisol were analyzed along with brain levels of dopamine (DA), 3,4-hydroxyphenylacetic acid (DOPAC, a major DA metabolite), seroton in (5-hydroxytryptamine, 5-HT), and 5-hydroxyindoleacetic acid (5-HIAA, a m ajor 5-HT metabolite). Transfer to a novel environment, alone as well as in combination with predator exposure, resulted in elevated plasma concentrat ions of glucose and cortisol. Moreover, exposure to these stressors resulte d in elevated brain levels of 5-HT and 5-HIAA, as well as elevated brain 5- HIAA/5-HT and DOPAC/DA ratios. Wild trout displayed significantly higher po st stress plasma glucose levels than domesticated fish. Similarly, followin g stress, brain 5-HIAA/5-HT and DOPAC/DA ratios were significantly higher i n wild than in domesticated fish. These differences were not caused by diff erences in brain levels of 5-HIAA and DOPAC, but instead by differences in brain 5-HT and DA concentrations. These results suggest that domestication results in attenuated stress responses in trout, and that alterations in br ain monoamine neurotransmission are part of this effect. Copyright (C) 2001 S. Karger AG. Basel.