Allostasis revisited: A perception, variation, and risk framework

The framework of allostasis, allostatic load and overload (i.e., stability through change) attempts to combine homeostasis processes in day-to-day responses physiology behavior. These include predictive changes environment such as seasons, facultative perturbations. latter can be severe, occur at any time, may present considerable additional challenges homeostasis. Hormonal cascades, the hypothalamo-pituitary-adrenal cortex (HPA) axis, play a key role perturbations across vertebrate taxa. Glucocorticoids have been implicated these relation energy balance that plays determining energetic demand (allostatic load) influencing subsequent behavior associated with coping. Circulating glucocorticoid levels are likely regulated part based on an individual’s proximity crisis, identified perturbation resistance potential (PRP). In model load, PRP is quantified difference between available resources all costs daily routines, life history stages (breeding, migration, molt so on), impact environmental change gradually or abruptly reflected by spikes blood hormone levels. pattern individual responsiveness vary has specific implications for activation mineralocorticoid vs glucocorticoid-type receptors, metabolizing enzymes other downstream factors target tissues. However, difficult metric measure. Here, we examine variety cues animals use inform them about status their probability crisis. We consider (1) elevation glucocorticoids endocrine “decision,” (2) error management strategies evaluating reflect predict impending differential receptor well further integrative “decisions” determine diverse sometimes contradictory effects its actions important consideration management. This perspective offers insight into basis intra- inter-individual variability opens avenue toward improving compatibility allostasis more classical views “stress”.