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 female mice,” 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 receptors were 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 reproductive cycle.”
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 interneurons. 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.”
Zach Veilleux | newswise
Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences
Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences