Oxytocin is produced in the hypothalamus (above the pituitary gland, behind the eyes) and stored in the pituitary gland. It is also produced in other body parts, including the sex glands of men and women.
Oxytocin has been called the love hormone or the bonding hormone because its release contributes to the social bonding that occurs between lovers, friends and colleagues. A study from Bar-llan University in Israel showed that fathers living with their partner and newborn had as much oxytocin in their blood as mothers, at one week postpartum and at 6 months. Mothers with high oxytocin levels provided more affectionate parenting, and fathers with high levels encouraged more exploration and attention to objects. The researchers were not sure whether these differences reflected cultural role expectations or were ‘indicative of distinct circuit effects of oxytocin in the male and female brain.’ The amounts of oxytocin found in each couple tended to be similar, although most people differ in the amount they produce.
The oxytocin that is released during sex and orgasm, and also in handholding, hugging and eye-gazing plays a role in keeping couples together, and keeping men attracted to their partners, according to studies at the University of Bonn in Germany and also at Emory University in Atlanta. There is an evolutionary benefit here for offspring survival.
(Another school of thought – not related to oxytocin - is that men are primed to have as many affairs as possible to spread their DNA. Examples of both these theories may be found in the course of a man’s life. Women have their own variation on these themes, but it’s exhausting to think of the numerous pregnancies that could occur with a variety of mates if evolution had its way. Fortunately, there’s birth control.)
Oxytocin is released in large amounts during labor; it causes uterine contraction and thereby facilitates delivery. A synthetic form of oxytocin, known as pitocin, is frequently given intravenously if labor is too slow. Oxytocin is produced during stimulation of the nipples by the infant’s mouth, and it produces milk release. Intravenous pitocin has been considered an important drug in the treatment of hemorrhage after birth, although newer drugs are taking its place.
Research into wound healing and oxytocin was carried out at Ohio State University. This unusual study was done with 37 couples admitted to a hospital for 24 hours. Participants were given small blister wounds on the arm. Each couple was then given instructions on how to interact, and asked to avoid topics that could cause marital dissension. Follow up of wound healing was done for 8 days. They found that people with higher levels of oxytocin had more rapid wound healing than others.
A relationship between addiction and oxytocin has been found at the University of Adelaide. Researchers looked at why there is a high level of variability in people’s oxytocin levels – they think that adversity early in life may be key. Oxytocin exists in the newborn and helps to create bonding with the mother. A difficult birth, disturbed bonding or abuse, deprivation or severe infection might act to prevent normal development of the oxytocin system by age 3. Later in life, people with low oxytocin levels may be more attracted to drugs and alcohol when under stress.
Here’s one of the latest and most amazing studies on oxytocin. Researchers at UC Berkeley have found that oxytocin helps to prevent muscle wasting with age and even osteoporosis. The study was done in mice, but is believed to be applicable to humans. The mice with osteoporosis had had their ovaries removed to mimic menopause. The animals with muscle wasting were given oxytocin injections under the skin, and regeneration to about 80% of the muscle strength seen in young mice occurred fairly rapidly. The title of the paper from Berkeley summarizes their findings: Oxytocin is an age-specific circulating hormone that is necessary for muscle maintenance and regerneration.
What are the take home messages of this discussion of oxytocin? Keep your relationships with significant others as happy as possible, with plenty of hugs, snuggles and massage. Do things that make you happy, like listening to your favorite music, or playing an instrument, singing, making art, walking outside, or getting a massage. See you on the trail.
Sadja Greenwood, MD, MPH past issues at on this blog
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