Oxytocin and affiliative behavior in prairie voles Open Access

Ross, Heather (2009)

Permanent URL: https://etd.library.emory.edu/concern/etds/2f75r874m?locale=en
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Abstract


Abstract
Oxytocin and affiliative behavior in prairie voles
By Heather E. Ross

Oxytocin is produced in the hypothalamus and released into the circulation through the
neurohypophyseal system. Peripherally released oxytocin facilitates parturition and
lactation. Centrally released oxytocin plays a role in maternal nurturing behavior and
affiliative behavior in adults. Oxytocin receptors in the nucleus accumbens have been
implicated in the regulation of alloparental behavior and pair bond formation in the
socially monogamous prairie vole. There are both interspecies differences in oxytocin
receptor density in the nucleus accumbens of monogamous and non-monogamous prairie
voles, as well as, individual differences within prairie voles, that are functionally related
to differences in affiliative behaviors. Here we show that the distribution of oxytocin-
immunoreactive fibers in the nucleus accumbens is conserved in prairie voles, mice and
rats, despite remarkable species differences in oxytocin receptor expression in the region.
However, the origin of these accumbal OT fibers is unknown. Using a combination of
site-specific and peripheral infusions of the retrograde tracer, Fluorogold, we demonstrate
that oxytocin-immunoreactive fibers in the nucleus accumbens likely originate from
paraventricular and supraoptic hypothalamic neurons. This distribution of retrogradely
labeled neurons is consistent with the hypothesis that striatal oxytocin fibers arise from
collaterals of magnocellular neurons of the neurohypophysial system. If correct, this may
serve to coordinate peripheral and central release of oxytocin with appropriate behavioral
responses associated with reproduction, including pair bonding after mating, and
maternal responsiveness following parturition and during lactation. In addition, we used
adeno-associated viral vector gene transfer to examine the functional relationship
between accumbal oxytocin receptor density and social behavior in prairie and meadow
voles. Adult female prairie voles that over-express oxytocin receptor in the nucleus
accumbens displayed accelerated partner preference formation after cohabitation with a
male, but did not display enhanced alloparental behavior. However, partner preference
was not facilitated in non-monogamous meadow voles by introducing oxytocin receptor
into the nucleus accumbens. These data are the first to demonstrate a direct relationship
between oxytocin receptor density in the nucleus accumbens and variation in social
attachment behaviors. Thus, individual variation in oxytocin receptor expression in the
striatum may contribute to natural diversity in social behaviors.


Table of Contents



TABLE OF CONTENTS


CHAPTER 1: GENERAL INTRODUCTION

1.1 Introduction 2


1.2 Coordinating Birth and Parental Care
3
1.3 Maternal Care in Rodents
4
1.4 Maternal Bonding in Sheep
7
1.5 Alloparental Behavior in Voles
9
1.6 Pup-Mother Interactions
12

1.7 Social Bonding in Adults
14

1.8 Social Recognition in Rodents
19

1.9 Social Cognition in Humans
22

1.10 Mediation of the Positive Effects of Social Support: stress
23
responses and immune function

1.11 Human Social Relationships
25

1.12 Neural Circuitry of the Oxytocin System
27

1.13 Characterization of Oxytocin Cells
27

1.14 Oxytocin Fibers of the Nucleus Accumbens
31
1.15 Conclusions
32
1.16 Dissertation Goals
32
CHAPTER 2: VARIATION IN OXYTOCIN RECEPTOR DENSITY IN THE
NUCLEUS ACCUMBENS HAS DIFFERENTIAL EFFECTS ON
AFFILIATIVE BEHAVIORS IN MONOGAMOUS AND POLYGAMOUS
VOLES

2.1
Abstract
35
2.2
Introduction
36

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