CF Ferris

Central vasopressin pathways have been implicated in the mediation of paternal behavior, selective aggression, and affiliation in monogamous prairie voles. Here we demonstrate markedly different patterns of brain vasopressin receptor binding in the monogamous prairie vole and the congeneric nonmonogamous (promiscuous) montane vole. Vasopressin binding was assessed with both 3H-vasopressin and 125I-sarc-AVP using receptor autoradiography. The specificity of binding was consistent with a V1a receptor, the saturation kinetics were similar in the two species, and neither species showed evidence of sexual dimorphisms. In the prairie vole, highest specific binding was observed in the accessory olfactory bulb, diagonal band, laterodorsal thalamus, and superior colliculus. In the montane vole, specific binding was observed in the accessory olfactory bulb and superior colliculus as well, but in several other regions with high levels of binding in the prairie vole, binding was low or undetectable in the montane vole. In this nonmonogamous species, specific binding was high in lateral septum. Functional studies demonstrated the induction of phosphoinositol by AVP in the septum of the montane vole but not in the prairie vole. The pattern of 125I-sarc-AVP binding to lateral septum may reflect the social organization of these two species, as similar differences in AVP receptor distribution in the lateral septum were also observed in two related species, pine voles and meadow voles, which are monogamous and nonmonogamous, respectively. These results, along with earlier studies of AVP's effects on pair bonding, suggest the importance of this neuropeptide for the mediation of behaviors related to social organization.

A vasopressin-sensitive mechanism within the medial preoptic area-anterior hypothalamus (MPOA-AH) appears to be essential for expression of a complex behavior involved in olfactory communication in Golden hamsters called flank marking. The present study investigated whether the induction of flank marking by arginine-vasopressin (AVP) within the MPOA-AH is mediated by a receptor that is more similar to the vasopressor (V1) or the antidiurectic (V2) AVP receptor. Adult male hamsters were anesthetized and implanted with a 26 gauge guide cannula stereotaxically aimed at the MPOA-AH and then microinjected with analogs of vasopressin, oxytocin, and selective V1 and V2 antagonists. Hamsters were tested for flank-marking behavior during a 5 or 10 min observation period following the injection of peptide in a vehicle of 100 nl of saline. None of the 15 analogs of AVP and oxytocin produced more flank marking than the 50.8 +/- 16.2 and 76.8 +/- 4.4 (mean +/- SEM; n = 4) flank marks observed following injection of AVP at the 1 or 10 ng dose, respectively. The number of flank marks produced by each analog was found to be highly related to the pressor activity of that analog at both the 1 ng (rho = +0.74, p less than 0.01) and 10 ng (rho = +0.82, p less than 0.01) doses. In contrast, no statistically reliable relationship between flank marking and the antidiuretic activity of these analogs was found at either dose (1 ng: rho = +0.07, p greater than 0.05; 10 ng: rho = +0.10, p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)