Newly discovered brain cells explain a prosocial effect of oxytocin

October 9, 2014, Rockefeller University
A newly discovered type of brain cell responds to oxytocin and so regulates female mice's interest in males, but only when the females are in heat. These star-shaped neurons are shown within a brain region called the medial prefrontal cortex. Credit: Laboratory of Molecular and Cellular Neuroscience at The Rockefeller University

Oxytocin, the body's natural love potion, helps couples fall in love, makes mothers bond with their babies, and encourages teams to work together. Now new research at Rockefeller University reveals a mechanism by which this prosocial hormone has its effect on interactions between the sexes, at least in certain situations. The key, it turns out, is a newly discovered class of brain cells.

"By identifying a new population of neurons activated by oxytocin, we have uncovered one way this chemical signal influences interactions between male and ," says Nathaniel Heintz, James and Marilyn Simons Professor and head of the Laboratory of Molecular Biology.

The findings, published today in Cell (October 9), had their beginnings in a search for a new type of interneuron, a specialized neuron that relays messages to other neurons across relatively short distances. As part of her doctoral thesis, Miho Nakajima began creating profiles of the genes expressed in interneurons using a technique known as translating ribosome affinity purification (TRAP) previously developed by the Heintz lab and Paul Greengard's Laboratory of Molecular and Cellular Neuroscience at Rockefeller. Within some profiles from the outer layer of the brain known as the cortex, she saw an intriguing protein: a receptor that responds to oxytocin.

"This raised the question: What is this small, scattered population of interneurons doing in response to this important signal, oxytocin?" Nakajima says. "Because oxytocin is most involved in social behaviors of females, we decided to focus our experiments on females."

To determine how these neurons, dubbed oxytocin receptor interneurons or OxtrINs, affected behavior when activated by oxytocin, she silenced only this class of interneurons and, in separate experiments, blocked the receptor's ability to detect oxytocin in some females. She then gave them a commonly used social behavior test: Given the choice between exploring a room with a male mouse or a room with an inanimate object – in this case a plastic Lego block – what would they do? Generally, a female mouse will go for the non-stackable choice. Legos just aren't that interesting to rodents. But Nakajima's results were confusing: Sometimes the mice with the silenced OxtrINs showed an abnormally high interest in the Lego, and sometimes they responded normally.

This led her to suspect the influence of the female reproductive cycle. In another round of experiments, she recorded whether the female mice were in estrus, the sexually receptive phase, or diestrus, a period of sexual inactivity. Estrus, it turned out, was key. Female mice in this phase showed an unusual lack of interest in the males when their receptor was inactivated. They mostly just sniffed at the Lego. There was no effect on mice is diestrus, and there was no effect if the male love interest was replaced with a female. When Nakajima tried the same alteration in males, there was also no effect.

"In general, OxtrINs appear to sit silently when not exposed to oxytocin," says Andreas Görlich, a postdoc in the lab who recorded the electrical activity of these neurons with and without the hormone. "The interesting part is that when exposed to oxytocin these neurons fire more frequently in female mice than they do in male mice, possibly reflecting the differences that showed up in the behavioral tests."

"We don't yet understand how, but we think oxytocin prompts mice in estrus to become interested in investigating their potential mates," Nakajima says. "This suggests that the social computation going on in a female mouse's brain differs depending on the stage of her ."

Oxytocin has similar effects for humans as for mice, however, it is not yet clear if the hormone influences the human version of this mouse interaction, or if it works through a similar population of . The results do, however, help explain how humans, mice and other mammals respond to changing social situations, Heintz says.

"Oxytocin responses have been studied in many parts of the brain, and it is clear that it, or other hormones like it, can impact behavior in different ways, in different contexts and in response to different physiological cues," he says. "In a general sense, this new research helps explain why social behavior depends on context as well as physiology."

Explore further: A cautionary note on oxytocin as a treatment for psychiatric disorders

More information: Cell, Nakajima et al.: "Oxytocin modulates female sociosexual behavior through a specific class of prefrontal cortical interneurons." www.cell.com/cell/abstract/S0092-8674(14)01169-6

Related Stories

A cautionary note on oxytocin as a treatment for psychiatric disorders

August 12, 2013
The hormone oxytocin is known for its widespread effects on social and reproductive processes, and recent data from intranasal administration in humans has produced hope for its use as a therapeutic in autism, schizophrenia, ...

Is a hormone the key to understanding borderline personality disorder?

September 4, 2014
In the current issue of Psychotherapy and Psychosomatics a group of German investigators is reporting on the potential effects of a hormone in borderline personality disorder. Besides affective instability and identity diffusion, ...

Hormone affects distance men keep from unknown women they find attractive

November 13, 2012
Men in committed relationships choose to keep a greater distance between themselves and an unknown woman they find attractive when given the hormone oxytocin, according to new research in the November 14 issue of The Journal ...

Surprise finding shows oxytocin strengthens bad memories and can increase fear and anxiety

July 22, 2013
It turns out the love hormone oxytocin is two-faced. Oxytocin has long been known as the warm, fuzzy hormone that promotes feelings of love, social bonding and well-being. It's even being tested as an anti-anxiety drug. But ...

Recommended for you

Neuroimaging study reveals 'hot spot' for cue-reactivity in substance-dependent population

November 20, 2018
When patients with dependence on alcohol, cocaine or nicotine are shown drug cues, or images related to the substance, an area of their brain known as the medial prefrontal cortex (mPFC) shows increased activity, report investigators ...

To predict the future, the brain has two clocks

November 20, 2018
That moment when you step on the gas pedal a split second before the light changes, or when you tap your toes even before the first piano note of Camila Cabello's "Havana" is struck. That's anticipatory timing.

When storing memories, brain prioritizes those experiences that are most rewarding

November 20, 2018
The brain's ability to preserve memories lies at the heart of our basic human experience. But how does the brain's mechanism for memory make sure we remember the most significant events and not clog our minds with superfluous ...

Researchers hope to be able to replace dysfunctional brain cells

November 20, 2018
A new study by researchers at Karolinska Institutet supports the theory that replacement of dysfunctional immune cells in the brain has therapeutic potential for neurodegenerative diseases like ALS and Alzheimer's disease. ...

White matter pathway and individual variability in human stereoacuity

November 20, 2018
Researchers in the Center for Information and Neural Networks (CiNet), the National Institute of Information and Communications Technology and Osaka University have identified a human white matter pathway associated with ...

Can genetic therapy help kids with Angelman syndrome overcome seizures?

November 20, 2018
Angelman syndrome is a genetic disease with no cure. Children grow up with severe intellectual disabilities and a range of other problems, arguably the worst of which are epileptic seizures. Now scientists at the UNC School ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

russell_russell
not rated yet Oct 11, 2014
This article's closing paragraph:

"Oxytocin responses have been studied in many parts of the brain, and it is clear that it, or other hormones like it, can impact behavior in different ways, in different contexts and in response to different physiological cues," he says. "In a general sense, this new research helps explain why social behavior depends on context as well as physiology."


is applicable to brain specific estrogen too:
http://phys.org/n...483.html

There are greatest common denominators if not parallels here too.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.