MODULATION OF PAIR BONDING IN FEMALE PRAIRIE VOLES (MICROTUS-OCHROGASTER) BY CORTICOSTERONE

Glucocorticoid levels in animals may respond to and influence the deve lopment of social attachments. This hypothesis was tested in prairie v oles (Microtus ochrogaster), monogamous rodents that form long-term he terosexual pair bonds. In socially naive female prairie voles, cohabit ation with an unfamiliar male resulted in a dramatic decline in serum corticosterone levels, When corticosterone levels were reduced via adr enalectomy, females developed partner preferences after 1 h of cohabit ation, while sham-operated and untreated females required 3 h or more of nonsexual cohabitation to establish a partner preference. In adrena lectomized and intact females, exogenous injections of corticosterone, given prior to social exposure, prevented the development of preferen ces for the cohabitating male. Although corticosterone inhibited the d evelopment of partner preferences, it did not interfere with the expre ssion of previously established social preferences. These results sugg est that social stimuli can modulate adrenal activity and that adrenal activity, in turn, is capable of influencing the formation of adult s ocial preferences in female prairie voles, The involvement of the adre nal axis in the formation of partner preferences and the subsequent de velopment of pair bonds provides a mechanism through which environment al and social factors may influence social organization in this specie s.