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The pheromones behind romance
EMBL’s Cornelius Gross, a neuroscientist based in Monterotondo, recently hosted Takefumi Kikusui, a researcher from Azabu University in Japan who wants to understand what is going on in our brains when we experience a sense of connection
Great chemistry between two people involves more than just the fluttering of eyelashes or the butterflies you feel in your stomach. Falling in love might actually be caused by a storm of biological reactions in your brain. From finding an ideal partner to the curious relationship we share with our canine friends, bonding behaviour is guided by some very complex – some might say “unromantic” – biochemistry. And Takefumi Kikusui, a researcher from the School of Veterinary Medicine, Azabu University, Japan, wants to learn more. He is hoping a spell in the inspiring environment of EMBL Monterotondo, just a stone’s throw from romantic Rome, could help him in his quest to explore the hormones and pheromones that interact with animals’ – including humans’ – “social brains” and control a significant part of our behaviour. Kikusui was invited by EMBL’s Cornelius Gross, a neurobiologist who focuses on fear and anxiety, to mobilise the chemistry between their own fields of research, which both look to find out why we do what we do. We caught up with Kikusui to find out more…
“Both Takefumi and I are interested in how animals respond to their social environments and how this is shaped by experience,” explains Cornelius Gross. “But our perspectives are different: he is a trained behaviorist – someone who is able to look deeply at the way animals behave and who appreciates how subtle differences in the environment can elicit different responses, while I am a trained molecular biologist who thinks more about the tools that could be used to image and manipulate the underlying neural pathways. So we’re a perfect match!”
What are your research interests?
I am a behavioural neurobiologist with a specific focus on what we call the “social brain”. Our studies focus on mouse behaviour and we are mainly interested in the neural processes that control bonding in different ways, such as between males and females and between parents and offspring. We are also interested in how these behaviours change depending on the environment in which the mice grow up. One particularly interesting theme my team is looking at is sexual attraction: we are often swept away by the romantic plots we see in the movies but for mice, at least, we found at the molecular level this attraction is more tightly linked to a pheromone found in mouse: ESP1. Male mice who are lucky enough to secrete higher levels of ESP1 attract more females. Although no human pheromone has been found yet, we strongly believe that the neuronal and hormonal mechanisms underlying bonding behaviours are similar across species.
We strongly believe that the neuronal and hormonal mechanisms underlying bonding behaviours are similar across species
Oxytocin, on the other hand, seems to work very similarly between mice and humans to foster social interactions. The level of this hormone rises in both mothers and their pups when they are together; this is very similar to what we observe when dogs and their human masters look at each other, so this hormone seems to play a role in controlling bonding in various animals. However, its reputation as the “cuddle hormone” is a huge over-simplification: its effects are very complex and we are still studying them in various species.
Stress hormones called glucocorticoids are also very important in shaping how we behave socially. Pups that are separated from their mothers early in life secret such hormones, and later in life they tend to show more fearful and aggressive behaviour, a mechanisms that may serve as a way for animals to be warned about and prepare for a more threatening social environment. Interestingly, the same seems to be true in humans where children exposed to psychological or physical abuse are themselves more abusing and violent in adulthood. Understanding the brain mechanisms involved could help identify people at risk for anti-social behavior and help them cope better with their social environment.
What is your impression of EMBL?
It is my second visit to EMBL’s campus in Monterotondo: the first one was seven years ago, after Cornelius had also spent time working in my lab in Japan. Coming back now is very interesting to see firsthand how his lab and his research have moved forward, but also to get another taste of the fantastic Italian coffee. Last time I came was also during the football World Cup and Italy had qualified. There was a great atmosphere and the football fan in me was obviously enthusiastic!
Are you formally collaborating with EMBL already?
No, but I think this visit was very productive and will be the beginning of some joint projects. For example, I’d like to develop a series of genetically modified mice. Cornelius and his team are experts in creating such models so I am really interested in learning from their experience. One of the postdocs in Cornelius’ lab is starting to use a behavioural test we developed and we will be collaborating to carry out the study. I would also be interested to host researchers from EMBL in my lab in Japan for several months to help us set up the equipment and the procedures necessary to work with transgenic mice.
