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The present study examines the developmental consequences of neonatal exposure to oxytocin on adult social behaviors in female prairie voles (Microtus ochrogaster). Female neonates were injected within 24 hours of birth with isotonic saline or one of four dosages of oxytocin (OT). As adults, females were tested in an elevated plus-maze paradigm (a measure of anxiety and exploratory behavior), and for alloparental behavior and partner preferences. At 2 mg/kg OT, females took longer to approach pups, but were the only group to form a statistically significant within-group partner preference. At 4 mg/kg OT, females retrieved pups significantly more frequently but no longer displayed a partner preference; while females treated developmentally with 8 mg/kg spent significantly more time in side-to-side contact with a male stranger than any other treatment group. OT may have broad developmental consequences, but these effects are not linear and may both increase and decrease the propensity to display behaviors such as pair-bonding.The neuropeptide oxytocin (OT) has been implicated in social behavior in both male and female mammals. OT's peripheral effects include the induction of parturition and milk let-down, while central OT has been associated with the onset of maternal behavior (Pedersen and Prange Jr., 1979;Pedersen et al., 1982;Pedersen and Boccia, 2002), and other positive social behaviors such as pair-bonding (Insel and Hulihan, 1995;Carter and Altemus, 1997;Cho et al., 1999) and male parental care (Bales et al., 2004b). It is also becoming evident that manipulations of OT and a related peptide, arginine vasopressin (AVP) during the perinatal period of life can have life-long implications for social behavior and neuroendocrine function (Stribley and Carter, 1999;Diaz-Cabiale et al., 2000;Carter, 2003;Lipschitz et al., 2003). These exposures can be either endogenous, through responses to touch, warmth (Uvnas-Moberg, 1998) or perhaps through OT in breast milk (Leake et al., 1981); they could also be pharmacological, for example through use of pitocin or an oxytocin antagonist to manipulate labor (Husslein, 2002).In this context, we have begun to examine the consequences of OT manipulations in early life for subsequent social behaviors and neuroendocrine variables. Because we were particularly interested in the developmental control of social behaviors such as pair-bond formation and biparental behaviors, we chose to study the socially monogamous prairie vole (Microtus ochrogaster). In this species both males and females display parental care and form selective partner preferences indicative of pair-bonding, although the mechanisms for these behaviors Please direct correspondence to: Karen L. Bales, Dept. of Psychology, One Shields Ave., University of California, Davis, CA 95616. Ph: (530) 754−5890, Fax: (530) 752−2087, email: klbales@ucdavis.edu Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this e...

The goal of this study was to examine the effects of early life experiences on the subsequent expression of traits characteristic of social monogamy in prairie voles (Microtus ochrogaster). During cage changes parents and their offspring were either transferred between cages in a cup (zero manipulation, MAN0) or with a gloved hand (one manipulation, MAN1). Following weaning the offspring were tested for alloparental behavior. In adulthood they were tested for the capacity to form partner preferences, behavior in an elevated plus-maze (EPM), and corticosterone levels. MAN0 males (but not females) showed lower levels of alloparental behavior than MAN1 males. MAN0 females (but not males) were less likely to form pair bonds than MAN1 females. MAN0 animals of both sexes were less exploratory in the EPM than MAN1 counterparts. These experiments support the hypothesis that behaviors used to characterize monogamy are vulnerable in a sex-specific manner to early experience.

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