FKBP5 expression is related to risky foraging in house sparrows

Responding appropriately to unpredictable challenges requires the ability to match phenotype to current conditions. The hypothalamic-pituitary-adrenal (HPA) axis is critical to this response. We recently suggested that HPA flexibility, the ability of an individual to mount appropriate glucocorticoid responses to different stressors, might be crucial to respond appropriately to the different challenges faced by wildlife. In a recent study in adult house sparrows (Passer domesticus), we showed i) that HPA flexibility was negatively related to hypothalamic expression of FKBP5 and ii) that central (brain) and peripheral (blood) expression levels were correlated. Here, we aimed at confirming this relationship in this species while also testing whether FKBP5 expression is related to foraging risk-taking behavior in the same individuals. We confirmed that FKBP5 expression in the hypothalamus is strongly correlated to expression in the blood. We also showed that hippocampal FKBP5 expression was positively related to eating novel foods and taking foraging risks. These results suggest that higher HPA flexibility may allow individuals to quickly and appropriately adjust their phenotypes to prevailing environmental conditions, particularly in regarding to foraging risks.