{"id":276,"date":"2014-08-09T21:11:17","date_gmt":"2014-08-09T21:11:17","guid":{"rendered":"http:\/\/joshmitteldorf.peachpuff-wolverine-566518.hostingersite.com\/?p=276"},"modified":"2014-08-11T01:42:19","modified_gmt":"2014-08-11T01:42:19","slug":"love-death-and-oxytocin","status":"publish","type":"post","link":"https:\/\/scienceblog.com\/joshmitteldorf\/2014\/08\/09\/love-death-and-oxytocin\/","title":{"rendered":"Love, Death, and Oxytocin"},"content":{"rendered":"

Oxytocin, the “love hormone”, is one of those blood factors that\u00a0we have less of as\u00a0we age.\u00a0A recent study connects loss of oxytocin with frailty and loss of muscle mass in old age. Could it be that oxytocin is the biochemical mediator that signals the body to live longer in response to loving connections and caring behaviors?<\/em><\/p>\n

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The body knows how to be young. \u00a0It had no trouble being young X years ago. \u00a0Now the body is choosing to be old, slowing down its repair and re-building functions, gradually destroying itself with inflammation, eliminating nerve and muscle cells via apoptosis. \u00a0In doing this, the body is following hormonal signals\u00a0that circulate in\u00a0the blood. \u00a0If the hormonal signals say, \u201cold\u201d, then the body is old; and if the hormonal signals say \u201cyoung\u201d, then the body will respond appropriately.<\/p>\n

This is my premise about what aging is, how it works, and how it can be addressed medically. \u00a0(Not everyone thinks this way \u2500 but you already know that.) \u00a0I call it the \u201cepigenetic theory of aging\u201d, and I\u2019ve blogged about it here<\/a> and written more technically here<\/a>. \u00a0Last summer, I listed some of the hormones that we don\u2019t have enough of<\/a> in old age, and some that we have too much of<\/a>.<\/p>\n

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Oxytocin is a Stem Cell Signal<\/strong><\/p>\n

Oxytocin levels\u00a0decline with age, and this summer, there was an article in Nature<\/a> suggesting that it may be one of those signals that help to keep us young. \u00a0Aging mice with extra oxytocin retained muscle mass that was lost by mice of similar age as their oxytocin naturally declined. Oxytocin signals the muscle stem cells (aka satellite cells) to actively divide and make more muscle cells. \u00a0The study\u2019s authors note, however, that the satellite cell receptor for oxytocin also declines with age, so that the problem of muscle loss is really compounded, and may need to be addressed at both ends.<\/p>\n

The reduction in muscle mass in humans starts in the third decade of life and accelerates after the fifth decade, resulting in a decrease in strength and agility. Muscle ageing is characterized by a deficiency in muscle regeneration after injury and by muscle atrophy associated with altered muscle function, defined as sarcopenia. The limiting step in muscle regeneration after injury is the activation of the muscle stem cells, or satellite cells…Satellite cells from old muscle are intrinsically able to repair damaged muscle, but are reversibly inhibited by the aged niche, yet can be quickly rescued for productive tissue repair by a number of experimental methods, including heterochronic parabiosis. While the rejuvenating effects of heterochronic parabiosis have been observed in several tissues such as muscle, brain, liver, pancreas and heart the molecular mechanisms are not fully understood and…to date, few circulating molecules decreasing with age have been identified to be responsible for skeletal muscle ageing.<\/p><\/blockquote>\n

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Other roles of oxytocin<\/strong><\/p>\n

Oxytocin is known for several other functions. \u00a0It suppresses our fear and protectiveness. Delivered intraveinously to women in labor (as Pitocin) it helps to strengthen contractions. \u00a0It is also thought to be related to bonding between parent and child, between lover and lover. \u00a0In popular literature, it is referred to as \u201cthe love hormone\u201d, with some justification. \u00a0But it doesn\u2019t necessarily make us feel good or improve our judgment; rather it shifts our feelings in the direction of more trusting, less self-protectiveness, more caring, with results that can be good or bad depending on circumstances.<\/p>\n

Oxytocin is released in the body in response to physical touching and especially during sexual orgasm. \u00a0Massage often triggers oxytocin.<\/p>\n

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What is \u201cheterochronic parabiosis\u201d?<\/strong><\/p>\n

The research comes from the lab of Irina and Mike Conboy<\/a>, who have pioneered work in \u201cheterochronic parabiosis\u201d. \u00a0This is an experimental setup in which an old mouse and a young mouse are joined surgically, like Siamese twins. \u00a0It has been noted that the admixture of young blood promotes wound healing and nerve growth in the older mouse. \u00a0This raises the promise of a possible path toward rejuvenation, but the experimental technique must be refined in order to answer the obvious questions<\/p>\n