Monogamous Behavior in Males
HORMONAL, GENETIC, and NEURAL mechanisms
Monogamous Behavior
socially monogamous
forms partner preference
highly affiliative
bi-parental
•
•
•
•
prarie vole
pine vole
california mouse
common marmoset
Non-Monogamous Behavior
socially promiscuous
forms no partner preference
asocial
non-paternal
•
•
•
•
montane vole
meadow vole
white-footed mouse
rhesus monkey
Affiliative Behavior test
Exp. Animal
Stranger
Partner Preference test
Partner
Exp. Animal
Stranger
Partner preference formation in
Prarie Voles
HORMONES
Role for Vasopressin (AVP)?
• in males:
–
–
–
–
communication
sexual behavior
aggression
pair bonding
In voles (and humans) mating
stimulates AVP release
Partner
Exp. Animal
Stranger
Affiliative Behavior
prarie vole
montane vole
Exp. Animal
Stranger
young et al, nature 1999
V1a receptor expression
prarie vole
Ventral Pallidum has
higer V1a expression
montane vole
Lim et al, Nature 2004
V1a receptor gene
GENETICS
--V1a receptor protein 99% homologous between vole species
--binding kinetics (affinity between hormone and receptor) identical
--expression level differences?
Young and Wang, Nature Neuroscience 2004
Meadow Vole: role of V1a
time with partner
time with stranger
• Inject viral vector into
specific brain areas
• vector contains
– lac Z gene (marker)
– V1a receptor gene
• Areas:
– ventral pallidum
– other areas
• mate meadow vole
– measure partner
preference
Control injection
into VP
V1a Injection
into other brain areas
V1a Injection
into ventral pallidum
partner preference behavior
Partner
Exp. Animal
Stranger
Transgenics in non-monogamous mice
• Inject prarie vole V1a
gene into mouse
embryo
• measure change in
affiliative behavior
after AVP injection as
an adult
Exp. Animal
Stranger
Monogamous Behavior in Males
HORMONAL, GENETIC, and NEURAL mechanisms
Monogamous Behavior
socially monogamous
forms partner preference
bi-parental
•
•
•
•
prarie vole
pine vole
california mouse
common marmoset
Non-Monogamous Behavior
socially promiscuous
forms no partner preference
non-paternal
•
•
•
•
montane vole
meadow vole
white-footed mouse
rhesus monkey
HIGHER V1a expression LOWER V1a expression
Ventral Pallidum
NEURAL
• Part of the reward/reinforcement pathway
– in lab rats:
• cocaine use activates neurons in ventral pallidum
• infuse psychostimulants directly into ventral pallidum
– subjects develop ‘conditioned place preference’ for
environment where injections occurred
• Hypothesis in voles:
– V1a in ventral pallidum: activation of this pathway
during mating enhances choice of partner later
– lack of V1a in non-monogamous voles results in no
induction of reward pathway, no preference for
partner later
HORMONAL
Summary
• Vasopressin (AVP) is involved in partner preference and
affiliative behavior in monogamous voles
• Differences in these behaviors between monogamous
and non-monogamous species lies in the V1a receptor
GENETIC
• monogamous voles have a different promoter that
increases receptor expression in the ventral pallidum
• induction of V1a receptor expression in nonmonogamous species induces monogamous-like behaior
NEURAL
• Ventral Pallidum appears to enhance partner preference
because it activates the ‘reward pathway’ during mating
V1a viral vector insertion into Prarie vole ventral pallidum increases affiliative behavi
without the need for mating first.
insertion into caudate putamen doesn’t have this effect
# of receptors present
associated behavioral response
prarie vole with V1a receptor antagonist
before mating with female
cerebrospinal fluid
AVP
oxytocin
after mating with female
cerebrospinal fluid (vehicle)
V1a receptor antagonist
oxytocin receptor antagonist
Winslow et al Nature 1993