Researchers have discovered an unexpected effect of oxytocin on muscle regeneration. One has to wonder just how much the fact that use of oxytocin is already approved by regulators factors into this work: there is a strong incentive for researchers to look for new marginal effects in the existing set of approved drugs and compounds rather than work on radically new and better medical technologies. This is because regulators impose vast costs on novel technologies, but only very large costs on reuse of existing treatments in new ways, and this structure percolates all the way back up the research chain due to its effects on funding. This is just one of many detrimental distorting effects of regulation on the course, speed, and effectiveness of medical research.
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. "Unfortunately, most of the molecules discovered so far to boost tissue regeneration are also associated with cancer, limiting their potential as treatments for humans. 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."
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. 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. "This is good because it demonstrates that extra oxytocin boosts aged tissue stem cells without making muscle stem cells divide uncontrollably." The researchers also found that blocking the effects of oxytocin in young mice rapidly compromised their ability to repair muscle, which resembled old tissue after an injury.