Vasopressin eliminates the expression of familiar odor bias in neonatal female mice through V1aR

Arginine-vasopressin (AVP) and the vasopressin Via receptor (V1aR) acting within the forebrain are involved in social behavior in adult animals. Much less is known about the function of V1aR in neurobehavioral development. In the present study, at post-natal day 8 (P8) in neonatal C57BL/6J mice, we map V1aR and use an olfactory exposure paradigm to assess a role for V1aR on olfactory preferences. In addition to V1aR in the lateral septum and ventral tegmental area, we observe V1aR in the neocortex and hippocampus, not typically observed in adult mice, implicating a developmental sensitive period for VlaR to modulate these brain areas in an experience-dependent manner. Males and females were tested on P8 for orienting preferences after exposure to a non-social odor, presented either when the mother was in the home cage (contingent) or when the mother had been removed from the home cage (not contingent). Wild-type female mice show a selective orienting bias toward the exposed odor, but only in the contingent condition. Males did not show orienting bias after either training condition. Female Avpr1a(-/-) mice showed strong familiar odor bias, regardless of the training condition. This finding led us to test the ability of AVP to diminish odor bias in females. Central application of AVP eliminated odor bias in Avpr1a(+/+), but not Avprla(-/-) female mice. Together, these data indicate that AVP acting at VlaR eliminates the expression of familiar odor bias in neonatal mice. This suggests a developmental role for AVP on familiarity bias, which has implications for species-typical life history trajectories of social learning and natal dispersal. (C) 2012 Elsevier Inc. All rights reserved.