Cortisol stress responsiveness is an essential feature of biobehavioural profiles as it is critically involved in the control of behaviour and provides the organism with energy to cope with challenge. The aim of this study was to examine whether cortisol stress responsiveness represents a temporally stable trait over the life time and how this is influenced by the social environment that is experienced during development.

For that purpose, a series of experiments in guinea pigs (Cavia aperea f. porcellus) was conducted in order to test for stability of interindividual differences in cortisol stress responsiveness during various life stages. When male guinea pigs housed in large mixed-sex colonies were repeatedly exposed singly to a novel enclosure, the acute cortisol stress response was remarkably stable during postweaning and early adolescent phases. That is, cortisol response values were individually consistent over retesting intervals from 20 to 30 days and 30 to 55 days of age, respectively. This stability was confirmed for adult animals (approximately 7 to 17 months) over even longer retesting intervals of about 2 months. In contrast, no significant consistency of cortisol responses was found from early to late adolescence (55 to 120 days), which covers the phase where colony-housed males show a socially mediated suppression of HPA reactivity. On the other hand, pair-housed males, which do not show suppressed HPA responsiveness during adolescence, exhibited highly stable individual differences in cortisol responses over exactly the same period.

Taken together, individual cortisol stress responsiveness seems to be a highly stable trait during most life stages. However, the social environment has remarkable influence on this stability during phases of increased developmental plasticity.

This study was supported by grants from the German Research Foundation (DFG-Forschergruppe FOR 1232, Sa389/11-1/2).