Fig. 1

Experimental design. UE-daughters: daughters of mothers living in an unstable social environment during pregnancy and lactation; SE-daughters: daughters of mothers living in a stable social environment during pregnancy and lactation. After weaning (day 20 ± 1 of age) UE-daughters as well as SE-daughters were held in pairs with an unfamiliar female of about the same age and from the same early environmental condition. On day 40 ± 3 of age, one UE-daughter and one SE-daughter were placed together in a new enclosure and stayed there for seven days, which was labelled the social encounter week. Spontaneous behavior (video) of UE-daughter/SE-daughter pairs was recorded around day 32 ± 3 of age; spontaneous behavior of UE- and SE-daughters was recorded on the first, second, fourth and last day of the social encounter week. Blood samples were taken one day before and on the first day of the social encounter week in order to determine plasma cortisol concentrations (C). A Cortisol Response Test (CRT) was performed one week prior to and on the last day of the social encounter week. Body weight (BW) was measured after each blood sampling as well as on the fourth day of the social encounter week