Vasopressin receptors control fidelity

Kofi kofi at anon.un
Sun Jun 20 22:33:28 EST 2004


As it turns out, allopregnanolone increases the basal release of 
vasopressin.  Don't know how V1Ar works in females, though.

<http://news.bbc.co.uk/1/hi/sci/tech/3812483.stm>

'Fidelity gene' found in voles
By Julianna Kettlewell 
BBC News Online science staff 


 
As with meadow voles, most mammal males play around

A single gene can turn the Don Juan of voles into an attentive 
home-loving husband, Nature magazine has reported. 

By altering the small animal's brain hormone chemistry, scientists have 
made a promiscuous meadow vole faithful - just like its prairie vole 
cousin. 

The researchers think this will lead to a greater understanding of how 
social behaviour is controlled in humans. 

The same hormone activity could play a role in disorders like autism 
where people can lack simple social skills. 

Falling in love 

Fewer than 5% of mammals are habitually monogamous. Prairie voles 
(Microtus ochrogaster) are among the select few. 

After mating, the males "fall in love": they stick close to their chosen 
one, guard her jealously and help her raise their young. 


 It could be that vasopressin plays a role in normal human social 
interactions 



Larry Young, Emory University 

Closely related meadow voles (Microtus pennsylvanicus), on the other 
hand, take a more standard approach. They mate with several females and 
pay little attention to their babies. 

Previous studies indicated a hormone called vasopressin encourages 
pair-bonding in prairie voles. 

Scientists had also noticed that promiscuous voles have fewer 
vasopressin (V1a) receptors, in a bit of their forebrain called the 
ventral pallidum region. 

To prove vasopressin has a "taming" effect, the researchers gave meadow 
voles extra V1a receptors in the ventral pallidum region of their 
brains. 

Reward system 

The results were remarkable. After the V1a receptor gene was introduced, 
the former playboys reformed their ways. 

Suddenly, they fixated on one female, choosing to mate with only her - 
even when other females tried to tempt them. 

How does one hormone have such a dramatic effect? Scientists put it down 
to a particular chain of events. 

They think that when the voles have sex, the hormone vasopressin is 
released. This hormone is then "picked up" by the V1a receptors in the 
ventral forebrain, which in turn trigger a neural "reward system". 

The reward system makes them feel happy, and they associate those 
feelings with the vole they have just mated with - which encourages them 
to stick around. 

"We think what happens is when the voles mate, vasopressin activates the 
reward centre, and it really makes the animals pay attention to who they 
are mating with," co-author Larry Young, from Emory University, Georgia, 
US, told BBC News Online. 

He continued: "It makes the voles think, 'when I'm with this partner I 
feel good'. And from then on, they want to spend their time with that 
particular partner." 

The researchers have concluded that the male meadow voles are 
promiscuous because they lack just one link in the chain: the V1a 
receptors in the ventral forebrain. 

Autism link? 

The implications of this study extend beyond Casanova voles, however. 
The strings of human behaviour might be pulled by similar hormones and 
similar pathways. 

"We know that vasopressin is released when humans have sex," said 
Professor Young. "Sex is probably involved in maintaining the bond 
between humans and vasopressin may play a role in that." 

Jealous wives might want to give their husbands a hefty dose of the V1a 
receptor gene, but Professor Young and his team are focussed on medical 
advances. 

Studies of this kind could, they say, open the lid on conditions where 
our social skills go wrong, such as in autism. 

 
The strings of human behaviour might be pulled by similar hormones and 
pathways

"Part of the reason we are doing this research is that we are trying to 
understand the social brain," explained Professor Young. "Why do we 
interact with other people, and what could be wrong in diseases like 
autism? 

"In autism, people are very aloof - they don't want to interact with 
others. It could be that vasopressin plays a role in normal human social 
interactions. 

"Two studies have already found there is a modest link between 
vasopressin and autism." 

Professor Joseph Piven, a psychiatry expert from the University of North 
Carolina at Chapel Hill, US, agrees the voles might reveal something 
interesting about autism. 

"This is a model where the voles have alterations in their social 
behaviours," he said. "And these alterations may be linked to the same 
processes that are going awry in autism." 

He continued: "No very strong links have been found yet between autism 
and vasopressin, but after studies like this people may take a closer 
look."



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