'Trust hormone' oxytocin helps rejuvenate old muscle

A study at the University of California, Berkeley, has found that a hormone, which is key for healthy muscles but declines with old age, can help rejuvenate old muscle tissue.

The findings, published in the journal Nature Communications, speculate that oxytocin could be a new solution in the treatment to target age-related muscle wasting or sarcopenia. It is secreted into the blood by the brain's pituitary gland but synthetic forms of oxytocin have already been developed and approved.

Previous research has already connected aging to other biochemical factors in blood but oxytocin is the first anti-aging molecule identified that is already approved by the Food and Drug Administration for clinical use in humans, according to the team of researchers. 

A synthetic form of oxytocin - Pitocin - is already used to help with labour and to control bleeding after birth. Clinical trials are also underway to test its ability to control 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 Dr Irina Conboy, associate professor of bioengineering.

She said their ambition is to find a molecule that, not only rejuvenates old muscle and other tissue, but can do this in the long term, without putting the patient at risk of cancer.

Dr Conboy and her research team consider oxytocin to be a good candidate due to its ability to reach every organ and it isn't linked to the development of tumours or interference with the immune system.

Oxytocin is found in both young boys and girls but it is unknown why the levels start to drop as the person ages, and what levels are necessary for maintaining healthy tissues.

The study found that, in mice, blood levels of oxytocin declined with age and showed fewer receptors for oxytocin in muscle stem cells than in younger mice. The team then 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.