UC Berkeley researchers have discovered that oxytocin — a hormone associated with maternal nurturing, social attachments, childbirth and sex — is indispensable for healthy muscle maintenance and repair. It is the latest target for development into a potential treatment for age-related muscle wasting.
A few other biochemical factors in blood have been connected to aging and disease in recent years, but oxytocin is the first anti-aging molecule identified that is approved by the Food and Drug Administration for clinical use in humans, the researchers said. Pitocin, a synthetic form of oxytocin, is already used to help with labor and to control bleeding after childbirth. Clinical trials of an oxytocin nasal spray are also underway to alleviate symptoms associated with mental disorders such as autism, schizophrenia and dementia.
“Unfortunately, most of the molecules discovered so far to boost tissue regeneration are also associated with cancer, limiting their potential as treatments for humans,” said study principal investigator Irina Conboy, associate professor of bioengineering. “Our quest is to find a molecule that not only rejuvenates old muscle and other tissue, but that can do so sustainably long-term without increasing the risk of cancer.”
Conboy and her research team say that oxytocin, secreted into the blood by the brain’s pituitary gland, is a good candidate because it is a broad range hormone that reaches every organ, and it is not known to be associated with tumors or to interfere with the immune system.
The new study determined that in mice, blood levels of oxytocin declined with age. They also showed that there are fewer receptors for oxytocin in muscle stem cells in old versus young mice.
To tease out oxytocin’s role in muscle repair, the researchers injected the hormone under the skin of old mice for four days, and then for five days more after the muscles were injured. After the nine-day treatment, they found that the muscles of the mice that had received oxytocin injections healed far better than those of a control group of mice without oxytocin.
“The action of oxytocin was fast,” said Elabd. “The repair of muscle in the old mice was at about 80 percent of what we saw in the young mice.”
Interestingly, giving young mice an extra boost of oxytocin did not seem to cause a significant change in muscle regeneration.