‘Love hormone’ may play wider role in social interaction than previously thought

Sep. 11, 2013 — Researchers at the Stanford University School of Medicine have shown that oxytocin — often referred to as “the love hormone” because of its importance in the formation and maintenance of strong mother-child and sexual attachments — is involved in a broader range of social interactions than previously understood.The discovery may have implications for neurological disorders such as autism, as well as for scientific conceptions of our evolutionary heritage.Scientists estimate that the advent of social living preceded the emergence of pair living by 35 million years. The new study suggests that oxytocin’s role in one-on-one bonding probably evolved from an existing, broader affinity for group living.Oxytocin is the focus of intense scrutiny for its apparent roles in establishing trust between people, and has been administered to children with autism spectrum disorders in clinical trials. The new study, published Sept. 12 in Nature, pinpoints a unique way in which oxytocin alters activity in a part of the brain that is crucial to experiencing the pleasant sensation neuroscientists call “reward.” The findings not only provide validity for ongoing trials of oxytocin in autistic patients, but also suggest possible new treatments for neuropsychiatric conditions in which social activity is impaired.”People with autism-spectrum disorders may not experience the normal reward the rest of us all get from being with our friends,” said Robert Malenka, MD, PhD, the study’s senior author. “For them, social interactions can be downright painful. So we asked, what in the brain makes you enjoy hanging out with your buddies?”Some genetic evidence suggests the awkward social interaction that is a hallmark of autism-spectrum disorders may be at least in part oxytocin-related. Certain variations in the gene that encodes the oxytocin receptor — a cell-surface protein that senses the substance’s presence — are associated with increased autism risk.Malenka, the Nancy Friend Pritzker Professor in Psychiatry and Behavioral Sciences, has spent the better part of two decades studying the reward system — a network of interconnected brain regions responsible for our sensation of pleasure in response to a variety of activities such as finding or eating food when we’re hungry, sleeping when we’re tired, having sex or acquiring a mate, or, in a pathological twist, taking addictive drugs. The reward system has evolved to reinforce behaviors that promote our survival, he said.For this study, Malenka and lead author Gül Dölen, MD, PhD, a postdoctoral scholar in his group with over 10 years of autism-research expertise, teamed up to untangle the complicated neurophysiological underpinnings of oxytocin’s role in social interactions. They focused on biochemical events taking place in a brain region called the nucleus accumbens, known for its centrality to the reward system.In the 1970s, biologists learned that in prairie voles, which mate for life, the nucleus accumbens is replete with oxytocin receptors. …

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A cautionary note on oxytocin as a treatment for psychiatric disorders

Aug. 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, and other disorders.However, this leap to human use is happening without previous animal studies of long-term oxytocin administration, and without knowledge of the neurobiological mechanisms involved in the behavioral findings.A new study now published in Biological Psychiatry indicates that the promising short-term effects often observed after a single dose of oxytocin may not translate to positive effects after long-term administration.This research was led by Dr. Karen Bales, Professor and Vice Chair of Psychology at the University of California. She and her colleagues examined the long-term effects of oxytocin treatment using the prairie vole, a small rodent that forms strong life-long pair bonds and is thus often used in studies of social behavior.Both male and female voles were treated with one of three dosages of intranasal oxytocin, administered daily from weaning through sexual maturity. During this time, the researchers observed and recorded the voles’ social interactions. They also conducted tests of social and anxiety-related behaviors in the adult voles, after the oxytocin treatment had finished, allowing them to measure any long-term effects.As expected, oxytocin treatment increased social behavior in male voles, similar to the effects repeatedly observed in humans. However, the long-term effects were concerning, with male voles showing deficits in their typical behaviors.”In this study, we showed that long-term exposure to oxytocin in adolescent male prairie voles led to disruption of social bond formation in these males as adults,” explained Bales. “Male prairie voles which received a dose similar to that being tested in humans, or even a lower dose, did not form pair-bonds normally with their pair-mate. Instead these males chose to associate with a strange female.”This important finding should suggest caution in the long-term use of intranasal oxytocin in developing humans.”The fact that long term treatment with oxytocin had the opposite impact of initial doses with the same substance suggests that special strategies will be needed if oxytocin is ever to become a long-term treatment for autism or schizophrenia,” said Dr. John Krystal, Editor of Biological Psychiatry.Bales agrees, and added, “In our continuing research program, we also have preliminary data suggesting that these treatments caused long-term changes in the oxytocin system. …

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Feeling stressed? Oxytocin could help you reach out to others for support

June 25, 2013 — The next time someone snubs you at a party and you think hiding is the solution to escape your feelings of rejection, think again. Scientists have shown that reaching out to other people during a stressful event is an effective way to improve your mood, and researchers at Concordia University suggest that the hormone oxytocin may help you accomplish just that.Mark Ellenbogen and Christopher Cardoso, researchers in Concordia’s Centre for Research in Human Development are taking a closer look at oxytocin, a hormone traditionally studied for its role in childbirth and breastfeeding, and more recently for its effect on social behaviour. Their latest study, published in the peer-reviewed journal Psychoneuroendocrinology, shows that oxytocin can increase a person’s trust in others following social rejection.Explains Ellenbogen, “that means that instead of the traditional ‘fight or flight’ response to social conflict where people get revved up to respond to a challenge or run away from it, oxytocin may promote the ‘tend and befriend’ response where people reach out to others for support after a stressful event. That can, in turn, strengthen social bonds and may be a healthier way to cope.”In a double-blind experiment, 100 students were administered either oxytocin or a placebo via a nasal spray, then subjected to social rejection. In a conversation that was staged to simulate real life, researchers posing as students disagreed with, interrupted and ignored the unsuspecting participants. Using mood and personality questionnaires, the data showed that participants who were particularly distressed after being snubbed by the researchers reported greater trust in other people if they sniffed oxytocin prior to the event, but not if they sniffed the placebo. In contrast, oxytocin had no effect on trust in those who were not emotionally affected by social rejection.Cardoso, who is a doctoral student in the Department of Psychology, says that studying oxytocin may provide future options for those who suffer from mental health conditions characterized by high levels of stress and low levels of social support, like depression. “If someone is feeling very distressed, oxytocin could promote social support seeking, and that may be especially helpful to those individuals,” he says, noting that people with depression tend to naturally withdraw even though reaching out to social support systems can alleviate depression and facilitate recovery.For Ellenbogen, who holds a Canada Research Chair in Developmental Psychopathology, the contribution of stress the development of mood disorders like depression and bipolar disorder has long been a research focus. “I’m concerned with the biological underpinnings of stress, particularly interpersonal stress, which is thought to be a strong predictor of these mental disorders. So, oxytocin is a natural fit with my interests,” says Ellenbogen. …

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