The social environment during pregnancy and lactation affects the female offsprings' endocrine status and behaviour in guinea pigs.

This study investigated the influence of the social environment during pregnancy and lactation on the female offsprings' endocrine parameters and behaviour. The subjects studied were daughters whose mothers had either lived in a stable social environment (SSE) during pregnancy and lactation (SE-mothers) or in an unstable social environment (USE) during this period of life (UE-mothers). The SSE was made by keeping the group composition (one male, five females) constant; in the USE situation every third day two females from different groups were exchanged. After weaning, 3 groups of daughters from UE-mothers (UE-daughters) and 3 groups of daughters from SE-mothers (SE-daughters), consisting of four females each, were established. From their 60th through their 80th day of age the spontaneous behaviour of the daughters was recorded in their home cages. On the endocrine level, cortisol and testosterone (T) concentration in serum as well as adrenal tyrosinehydroxylase activities in both adrenals and their weight were determined. UE-daughters displayed significantly higher amounts of male-typical courtship and play behaviour than SE-daughters. This behavioural masculinization corresponded with significantly higher T in UE- than SE-daughters. Cortisol levels did not differ between both categories of females. Significantly higher tyrosinehydroxylase activities and adrenal weight in UE- than SE-daughters pointed, however, to higher degrees of stress response in UE-daughters. Thus, the instability of the social environment during pregnancy and lactation has distinct effects on the behaviour and endocrine system of the female offspring.