The effects of peptides on partner preference formation are predicted by habitat in prairie voles

This study tested the hypothesis that intraspecific variations in mating sy stems are correlated with differences in the capacity of peripheral arginin e vasopressin (AVP) to facilitate partner preferences. It has been hypothes ized that differences in environmental conditions, Kansas being more xeric than Illinois, are responsible for some of the intraspecific differences in the mating systems between Kansas (KN) and Illinois (IL) prairie voles. We predicted that prairie voles from KN would be more behaviorally sensitive to peripheral AVP than prairie voles from IL. To test this hypothesis 60- t o 120-day-old male and female, lab-reared, prairie voles originating from K N and IL received three subcutaneous injections of AVP or isotonic saline. Animals were then placed with an adult member of the opposite sex, designat ed a "partner," for a 1-hour period of cohabitation and subsequently tested for preference for the familiar partner Versus a comparable stranger. Only KN males treated with AVP displayed a significant preference for the partn er. Using the same experimental paradigm we also examined the ability of pe ripheral oxytocin (OT) to facilitate partner preference in KN prairie voles . OT facilitated partner preference in females, but not males. This finding was consistent with previous results describing the effects of peripheral OT in IL prairie voles. We also examined the hypothesis that the differenti al response of KN and IL males would be associated with differences in the distribution of AVP (V-1a) receptors. However, there was no apparent differ ence in the distribution of V-1a receptors between KN and IL males. The res ults of this study indicate that there is both intraspecific and intersexua l variation in the regulation of social behavior in prairie voles. In addit ion, these findings suggest that the proximate causes of intraspecific vari ation may be predicted by knowledge of the habitat of origin. (C) 2001 Acad emic Press.