Trust hormone oxytocin helps old muscle work like new, study finds

BERKELEY

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, and that in mice it declines with age.

The healthy muscle tissue on the left is from a young mouse. The ability of muscle to repair itself decreases with age, as evidenced by the middle image of old muscle tissue, which shows a lower density of muscle fibers, increased scar tissue and inflammation. The addition of oxytocin to the blood of old mice rapidly rejuvenates the old muscle, as shown on the right. (Photos by Wendy Cousin and Christian Elabd, UC Berkeley)

The new study, published today (June 10) in the journal Nature Communications, presents oxytocin as the latest treatment target for age-related muscle wasting, or sarcopenia.

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 brains 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.

A happy hormone

Oxytocin is sometimes referred to as the trust hormone because of its association with romance and friendship. It is released with a warm hug, a grasped hand or a loving gaze, and it increases libido. The hormone kicks into high gear during and after childbirth, helping new mothers bond with and breastfeed their new babies.

This is the hormone that makes your heart melt when you see kittens, puppies and human babies, said Conboy, who is also a member of the Berkeley Stem Cell Center and of the California Institute for Quantitative Biosciences (QB3). There is an ongoing joke among my research team that were all happy, friendly and trusting because oxytocin permeates the lab.

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Trust hormone oxytocin helps old muscle work like new, study finds