The researchers also identified one of the factors circulating in young blood that helps to rejuvenate old tissues. This is oxytocin, a hormone produced in the brain and familiar to many people as the substance that aids contraction of the uterus in childbirth. ‘Oxytocin has a direct effect on muscle stem cells,’ explains Irina. ‘It has receptors on muscle stem cells, and without oxytocin muscle doesn't repair well; it does not function well, and it is replaced by fat. With ageing, oxytocin levels in blood decline about threefold and oxytocin receptors become less present.’
