A new version of the so-called “love hormone” oxytocin has been created by scientists in the hope it could be used to treat conditions such as anxiety and schizophrenia.
Oxytocin molecules have all sorts of functions in the human body. They bind with receptors in the brain and in doing so influence maternal care, social interactions and stress and anxiety levels. The hormone also has a role in controlling women going into labour.
The new substance is thought to have the potential to induce fewer of the side effects currently associated with oxytocin treatment.
"The downside to oxytocin is that it activates a number of receptors, some of which can lead to unwanted side effects," said Dr Markus Muttenthaler, a medicinal chemist at the University of Queensland, who led the research.
Oxytocin’s many functions mean that it has medicinal value. During labour, for example, women may be offered an oxytocin drip to make their contractions stronger.
However, if used at high levels this treatment can cause unpleasant side effects such as cardiovascular problems or uterine rupture.
The hormone has also been suggested as a treatment for various conditions including anxiety, depression, addiction, anorexia and schizophrenia owing to its ability to promote social and bonding behaviour.
But the dangerous side effects associated with oxytocin make application in humans difficult.
The new substance – outlined in a new paper in the journal Science Signaling, could provide a viable alternative.
"The new compound we have developed is just as potent as oxytocin, but shows improved selectivity for the oxytocin receptor, potentially reducing dangerous side effects,” said Dr Muttenthaler.
The research team tested their compound, a version of oxytocin with “subtle modifications”, on mice, and found their test subjects overcame social fear rapidly.
This suggests a potential role in treating conditions that are characterised by such fear.
“As a researcher specialising in oxytocin and mental health, I welcome the development of selective oxytocin receptor agonist,” said Dr Alexis Bailey, a neuropharmacologist at St George’s University of London who was not involved in the study.
He added that there is “good evidence” for the benefits of oxytocin in some conditions where few other treatments are available, such as autism, but he noted more research is required to determine the medicinal potential of both oxytocin and synthetic oxytocin for mental health issues.
Dr Arianna Di Florio, a psychiatrist at Cardiff University, agreed that knowledge of the potential benefits of oxytocin is still in its early days.
“There is hype because it is a very interesting molecule,” she said. But she pointed out that it is "not clinical practice" and "there is no robust evidence that supports it in everyday use.”
She said that while side effects are one issue, a bigger problem might be the fact that the beneficial effects of oxytocin use in people with anxiety disorders could also result from the placebo effect. This would mean oxytocin has far less value as a medicine.
Nevertheless, Dr Muttenthaler and his colleagues are looking to improve the drug properties of their new substance, and carry out more extensive studies of its therapeutic potential.
"The new compound is not only a promising lead for future treatments but also important for understanding the role of the oxytocin receptor in health and disease,” he said.
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