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Monogamous Behavior in Males
• prarie vole• pine vole• california mouse• common marmoset
Non-Monogamous Behaviorsocially promiscuousforms no partner preferenceasocialnon-paternal
HORMONAL, GENETIC, and NEURAL mechanisms
Affiliative Behavior test
Partner Preference test
StrangerExp. AnimalPartner
StrangerExp. Animal
Partner preference formation in Prarie Voles
StrangerExp. AnimalPartner
Role for Vasopressin (AVP)?
• in males:– communication– sexual behavior– aggression– pair bonding
HORMONES
In voles (and humans) mating stimulates AVP release
prarie vole
montane vole
young et al, nature 1999
StrangerExp. Animal
Affiliative Behavior
prarie vole
montane vole
Lim et al, Nature 2004
V1a receptor expression
Ventral Pallidum has higer V1a expression
Young and Wang, Nature Neuroscience 2004
V1a receptor gene--V1a receptor protein 99% homologous between vole species--binding kinetics (affinity between hormone and receptor) identical--expression level differences?
GENETICS
StrangerExp. AnimalPartner
partner preference behavior
Meadow Vole: role of V1a
• 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
time with partner
time with stranger
Control injectioninto VP
V1a Injectioninto other brain areas
V1a Injectioninto ventral pallidum
Transgenics in non-monogamous mice
• Inject prarie vole V1a gene into mouse embryo
• measure change in affiliative behavior after AVP injection as an adult
StrangerExp. Animal
Monogamous Behavior in Males
• prarie vole• pine vole• california mouse• common marmoset
Non-Monogamous Behaviorsocially promiscuousforms no partner preferencenon-paternal
HORMONAL, GENETIC, and NEURAL mechanisms
HIGHER V1a expression LOWER V1a expression
Ventral Pallidum• 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
NEURAL
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
• monogamous voles have a different promoter that increases receptor expression in the ventral pallidum
• induction of V1a receptor expression in non-monogamous species induces monogamous-like behaior
• Ventral Pallidum appears to enhance partner preference because it activates the ‘reward pathway’ during mating
NEURAL
GENETIC
HORMONAL
V1a viral vector insertion into Prarie vole ventral pallidum increases affiliative behaviorwithout the need for mating first.insertion into caudate putamen doesn’t have this effect
# of receptors present associated behavioral response