Oxytocin and the Biology of Love: Too Much of a Good Thing?

Sue Carter, PhD


May 09, 2017

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Hi. My name is Sue Carter. I am director of the Kinsey Institute at Indiana University. I am a biologist and I study the biology of social behavior and what humans call "love."

I began this work accidentally. I was studying pair-bonding and social behavior in animals, and as my research evolved, I discovered and realized that there had to be a physiology for love—a biology for love. The most logical candidate was oxytocin.

Oxytocin had already been called the "hormone of mother love" by people studying maternal behavior in animals and humans. My research took that to the level of comparing adult-adult relationships and using a prairie vole animal model. Prairie voles are small rodents that form lifelong pair-bonds. Our first studies with prairie voles were done in collaboration with Lowell Getz at the University of Illinois, where I was working at the time. Lowell found that prairie voles lived two to a nest—the same pair—for life. At first, he did not believe it. No one believed it because these were small rodents and it was widely accepted that rodents couldn't form pair-bonds and weren't monogamous. Our study[1] showed that they did form pair-bonds and they were monogamous, but the monogamy was social. They cared who they were with. They were much more likely to mate with a stranger than to sit and touch a stranger. We began to study the neurology, biology, social behavior, and evolution of these processes.

My work now is focused on the developmental effects of oxytocin. I am especially concerned because oxytocin is widely manipulated in birth.[2,3] It is used to induce labor and to facilitate other processes, but without taking into account the fact that oxytocin reaches the brain. It probably reaches the mother's brain, and in our animal models we know that it has lifelong effects on the baby.

Today at the Endocrine Society Annual Meeting, I talked about the epigenetic effects of oxytocin.[4] We are discovering that long-lasting changes in the oxytocin receptor gene are induced by the birth process itself, by maternal behavior, and by being exposed to exogenous oxytocin. A little oxytocin seems to be good, but large doses can disrupt the process—especially the development of the baby.

I do this work with another collaborator, Jessica Connelly from the University of Virginia. Dr Connelly has developed a lot of tools for measuring oxytocin and methylation. We are trying to understand what causes oxytocin, a hormone that can have benefits to the human body, to be released and its consequences, both as a natural hormone and as a hormone given exogenously. This is my area of interest. I am passionate and very excited about bringing other people to these questions.

Thank you.


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