THE EFFECTS OF STRESS ON SOCIAL PREFERENCES ARE SEXUALLY DIMORPHIC INPRAIRIE VOLES

Prairie voles (Microtus ochrogaster) are mo nogamous rodents that form pair bonds characterized by a preference for a familiar social partne r. In male prairie voles, exposure to either the stress of swimming or exogenous injections of corticosterone facilitate the development of a social preference for a female with which the male was paired after injection or swimming. Conversely, adrenalectomy inhibits partner pref erence formation in males and the behavioral effects of adrenalectomy are reversed by corticosterone replacement. In female prairie voles, s wim stress interferes with the development of social preferences and c orticosterone treatments inhibit the formation of partner preferences, while adrenalectomized females form preferences more quickly than adr enally intact controls. Because sex differences in both behavior and p hysiology are typically reduced in monogamous species, eve initially p redicted that male and female prairie voles would exhibit similar beha vioral responses to corticosterone. However, our findings suggest an u nanticipated sexual dimorphism in the physiological processes modulati ng social preferences. This dimorphic involvement of stress hormones i n pair bonding provides a proximate mechanism for regulating social or ganization, while permitting males and females to adapt their reproduc tive strategies in response to environmental challenges.