Measuring Endocrine (Cortisol) Responses of Zebrafish to Stress

The zebrafish (Danio rerio ) is rapidly becoming a popular model species in stress and neuroscience research. Their behavior, robustly affected by environmental and pharmacological manipulations, can be paralleled by physiological (endocrine) analysis. Zebrafish have a hypothalamic-pituitary-interrenal (HPI) axis, which is homologous to the human hypothalamic-pituitary-adrenal (HPA) axis. While mice and rats use corticosterone as their main stress hormone, both humans and zebrafish utilize cortisol. This protocol explains the whole-body cortisol extraction procedure and the use of the human salivary cortisol ELISA kit to measure the amount of cortisol in each zebrafish sample. The ability to correlate physiological data from individual fish with behavioral data provides researchers with a valuable tool for investigating stress and anxiety, and contributes to the utility of zebrafish neurobehavioral models of stress.