The environmental changes interfere with vertebrate endocrine systems. The endocrine biomarkers are used to indicate the condition of both free -ranging and farmed animals. The aim of this study was to show an impact of environmental changes on arginine vasotocin (AVT), isotocin (IT) and melatonin (MEL) in selected fish species. AVT and IT are neurohormones synthesized in hypothalamic nuclei and released to the blood stream in the neurohypophysis. Changes in hypothalamic, pituitary and plasma AVT and IT concentrations were found in many fish species subjected to different type of stress, i.e. confinement, disturbance, high density, food deprivation or osmotic. An effect of stress on nonapeptides' synthesis and release depends on the type of stress stimuli. MEL, synthesised mainly in pineal organ, is a well -known scavenger of free radicals and serves as a sensitive, first -line defensive molecule in the protective mechanism of organisms. Thus alterations in pineal and plasma MEL levels could be useful biochemical markers of exposure to stress. A role of AVT, IT and MEL in stress axis of fish has been suggested. AVT, IT and MEL can be considered as hormonal markers of the internal state of the individual and thus seems to be good candidates for welfare indicators.

Trabajo resentado en el COST 867 International Workshop on Fish Welfare, celebrado en Madrid del 8 al 10 de febrero de 2011.

Peer Reviewed