Beyond Cuddling: Oxytocin and the Brain


by Kayt Sukel

February 14, 2011

Despite the variety of research topics one can find at the annual Society for Neuroscience meeting, one word, oxytocin, kept popping up at this year’s conference. This small neuropeptide, produced in two specialized areas of the hypothalamus, was mentioned in nearly 100 abstracts published in the meeting program. Though oxytocin has long been linked to maternal and romantic bonds, giving it the nickname of the “cuddle chemical,” new research presented at Neuroscience 2010 suggests its reach goes far beyond cuddling. Oxytocin may have something to say about a variety of conditions and emotional states including autism, anxiety, happiness, and susceptibility to advertising messages. This research is still preliminary—researchers caution that they don't know what potential side-effects or long-term effects of taking the hormone may be.

Potential treatments for autism

Larry Young, a neuroscientist at Emory University, has been studying the formation of pair bonds in prairie voles, a monogamous rodent, for nearly a decade. His lab has demonstrated that oxytocin is an important component to these bonds, as well as to several other facets of social interaction. During a special lecture at the conference, Young suggested increasing oxytocin levels, either directly or indirectly through a drug like Melanotan II (a skin cancer treatment that also releases oxytocin), may help reduce the social deficits seen in autism spectrum disorder. He cited several studies that have shown that giving people oxytocin increases eye gaze, enhances trust and empathy, and helps them better infer the emotional state of others. These converging results, he argued, suggests a role for the oxytocin system in the development of novel autism treatments.

“There have been several studies that have come out, some just this year, showing that intranasal oxytocin actually enhances some aspects of social cognition in humans,” says Young. “Since there are no animal models of autism, perhaps prairie voles can be useful in this case and help us design new drugs to enhance social functioning in autism.”

Young has yet to begin work with autistic patients. He has, however, founded the Center for Translational Social Neuroscience at Emory in hopes of recruiting oxytocin researchers who work at the molecular to the human level to direct what he hopes will lead to innovative autism treatments.

A reduction in anxiety, together

Oxytocin has also been heralded as an anti-stress agent, a chemical involved in feelings of calm and contentment—in fact, some researchers are looking at this chemical as a possible antidepressant treatment. But it would seem the chemical does not work in isolation. Jason Yee, a postdoctoral fellow at University of Illinois at Chicago, presented new results at the meeting demonstrating oxytocin’s calming effects are at their best when stressed animals recover with a companion.

Yee treated prairie voles with oxytocin and then stressed them by putting them into a wet cage, an environment meant to mimic a flooded burrow in the wild. The animals were then put into a dry cage alone or with a companion. Most of the voles tried to escape the dry cage during the recovery period, a common anxious behavior observed when animals are stressed. But the animals that were paired with a friend showed fewer of these escape attempts. Furthermore, the animals showed higher levels of oxytocin in their blood than those who recovered solo, despite the fact they received identical administrations of the neuropeptide prior to the stressor.

“Oxytocin isn’t simply an anti-stress hormone,” says Yee. “What oxytocin is probably doing is increasing an organism’s ability to adapt to its given environment not just decreasing corticosteroid and stress hormone levels.”

Beyond animal models

Much of the oxytocin work done to date has been on animal models like the prairie vole. But Paul Zak, a researcher at Claremont Graduate University, has been studying the effects of oxytocin administration in humans. Zak had previously demonstrated that an economic game where a stranger sends a study participant some money results in an increase of oxytocin in the participants' bloodstream. He also saw a natural variation in how much of the neuropeptide is released across study participants. In a game correlate, these high oxytocin releasers are also more likely to share their unexpected windfall, and more of it, with a stranger if asked. Given these findings, Zak wondered if people who release more oxytocin in these kinds of tasks are happier overall.

Before undertaking the economic game task, sixty women volunteers filled out surveys that measured mood, relationships, reactions to stress, and life satisfaction. The high-oxytocin-releasing women consistently demonstrated greater resilience to adverse events, better mood, better life satisfaction and strong attachments to others.

“These women, essentially, have more friendships, higher quality romantic relationships, they reciprocate more with strangers, and they have more sex with fewer partners,” says Zak. “That’s why we called this study, ‘What Makes Women Happy.’”

In a second study, Zak looked at oxytocin’s influence in how people perceive advertisements.

“Why are there puppies in toilet paper commercials?  Puppies have nothing to do with toilet paper,” says Zak. “But they do make us feel good.” Zak argues that those good feelings may make us more likely to buy a certain product. And the basis of that good feeling may be linked to oxytocin.

Zak and colleagues asked male study participants to watch a public service announcement for a charity after sniffing oxytocin spray or a placebo. After watching, they were asked about their feelings as well as offered an opportunity to donate a portion of the money they earned from participating in the experiment to the charity in the advertisement. Individuals who sniffed the oxytocin gave 56 percent more money to causes than those in the placebo condition, suggesting this neuropeptide may make us more susceptible to advertising messages.

Still many unknowns

Sue Carter, a pioneer in the study of this neuropeptide, cautions people to be careful. Though these studies are promising and the idea of oxytocin treatment persuasive, she said we still don’t know enough of what the longterm effects of oxytocin use may be.

“Oxytocin is not a controlled substance,” says Carter. “It’s available on the Internet and people are already using it. Thousands of people are going to talk of using it. And this is totally in the absence of any research either on the long term behavioral effects of the side effects of using these chemicals.”