17 June 2014

Oxytocin rejuvenates muscles

Researchers at the University of California at Berkeley, working under the guidance of Dr. Irina Conboy, have found that oxytocin – a hormone responsible for maternal instinct, social attachment, uterine contractions during childbirth and sexual arousal – is necessary to maintain the health and youth of muscle tissue. Moreover, its level in the body of mice decreases as they age.

An earlier study by the authors showed that the administration of oxytocin helps prevent the development of osteoporosis in female mice whose ovaries were removed in order to simulate premature menopause.

Further study of this issue has demonstrated that the level of oxytocin in the body of animals decreases with age. Moreover, it turned out that aging is accompanied by a decrease in the number of receptors for this hormone on muscle stem cells.

To find out the role of oxytocin in the process of maintaining the functionality of muscle tissue, the researchers subcutaneously injected a drug of this hormone into old mice for four days. After that, they damaged the muscle tissue of the animals and for the next five days carried out a second cycle of subcutaneous injections of oxytocin. This 9-day therapy significantly increased the efficiency of muscle tissue regeneration in animals compared to the results of the control group. Oxytocin increased the ability of the muscle tissue of old animals to a level corresponding to about 80% of the regenerative capacity of the muscle tissue of young mice.

The middle photo shows the result of regeneration of the muscle tissue of an old mouse:
low density of muscle fibers, scar tissue formation and inflammation.
The introduction of oxytocin provides the result of regeneration of old muscles (right),
comparable to the result of regeneration of young muscles (left).
Photo by Wendy Cousin and Christian Elabd, UC Berkeley.

At the same time, the administration of additional oxytocin to young animals did not have a significant effect on the ability of their muscles to regenerate.

Another series of experiments showed that blocking the effects of oxytocin in young mice quickly "ages" their muscles, impairing their ability to regenerate.

The results of the study of mice without a functional oxytocin gene and their comparison with normal animals confirmed the observations made. In childhood, such animals did not differ from normal ones, but immediately after reaching maturity, they showed signs of premature aging.

There is evidence that oxytocin improves the condition of bone tissue and may be useful in the fight against obesity. The authors plan to study the supposed ability of this hormone to increase the duration of healthy life of animals, and possibly humans.

They note that to date oxytocin is the only compound involved in the aging process and the development of associated diseases, the clinical use of which is approved by the U.S. Food and Drug Administration. The synthetic form of the hormone has long been used to stimulate labor contractions and prevent subsequent uterine bleeding. The hormone preparation in the form of a nasal spray is undergoing clinical trials as a means of relieving symptoms associated with mental illnesses such as autism, schizophrenia and dementia. Moreover, oxytocin is a broad-spectrum hormone that is not associated with the development of tumors and does not affect the functioning of the immune system.

Article by Christian Elabd et al. Oxytocin is an age-specific circulating hormone that is necessary for muscle maintenance and regeneration published in the journal Nature Communications.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of California, Berkeley:
‘Trust hormone’ oxytocin helps old muscle work like new, study finds.


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