It’s official: love keeps us young, kind of. More specifically, oxytocin — a hormone associated with maternal nurturing, social attachments, childbirth and yes, sex — has the ability to make old muscles young. A UC Berkeley news release reports that researchers at the school injected the hormone, which boosts libido and sadly, declines with age, 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 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. The researchers point out that oxytocin is sometimes referred to as the “trust hormone” because of its association with romance and friendship. It kicks into high gear during and after childbirth, helping new mothers bond with and breastfeed their new babies. Read more from UC Berkeley.