Stimulation of the nipple during breastfeeding leads to increased oxytocin production and secretion into the blood, which then causes milk to be let down into the breast. The positive feedback cycle is maintained until the baby stops suckling. The production of oxytocin during childbirth is also self-limiting; release of the hormone is stopped once the baby is delivered. At present, the implications of having too much oxytocin are not clear. This may cause difficulty in passing urine.
It may be possible to treat this condition by manipulating oxytocin levels; however, more research is needed before any possible treatments are available. Similarly, it is not fully understood at present if there are any implications of having too little oxytocin in the body.
A lack of oxytocin in a nursing mother would prevent the milk-ejection reflex and prevent breastfeeding. Low oxytocin levels have been linked to autism and autistic spectrum disorders e.
Asperger syndrome — a key element of these disorders being poor social functioning. Some scientists believe oxytocin could be used to treat these disorders.
In addition, low oxytocin has been linked to depressive symptoms and it has been proposed as a treatment for depressive disorders. The oxytocin pulses induced by skin-to-skin contact are more long lasting than those observed during labor and breastfeeding. The maternal release of oxytocin is induced by activation of sensory nerves in the skin, which are activated by touch, warmth, and stroking in connection with skin-to-skin contact with the baby and also by massage-like hand movements performed by the baby.
Nissen et al. The skin-to-skin contact between mother and infant after birth is linked to an increase in maternal, vocal and tactile interaction with the child. In addition the mother looks and smiles more at the baby Velandia et al. At the same time anti-stress effects are induced as the mother becomes calmer and cortisol levels drop Handlin et al. The newborn infant produces its own oxytocin. Skin-to-skin contact after birth is in newborns, like in the mother, associated with increased social interaction.
The newborns perform a spontaneous breast seeking behavior breast crawling and they vocalize more than infants not being allowed skin-to-skin contact. In addition they become calmer and stop crying Widstrom et al. Powerful anti-stress effects are induced; cortisol levels fall, pulse rate becomes regularized and skin temperature increases as a sign of decreased sympathetic nervous tone Bystrova et al.
Birth is a stressful event and high stress levels are of importance for the baby during birth and also for some postnatal, physiological adaptations to occur. It is of equal importance to dampen the high stress levels as soon as possible after birth.
This conversion from a state of stress to a state of calm is induced in a natural way by the skin-to-skin contact with the mother immediately after birth and in this way skin-to-skin contact after birth serves to reverse the stress of being born Bystrova et al. The high levels of oxytocin, which are induced during labor, are of importance for oxytocin release and oxytocin mediated effects caused by skin-to-skin contact and suckling after birth.
This is demonstrated by the finding that skin-to-skin contact and suckling fail to induce any oxytocin release in mothers who have been subjected to an elective Cesarean Section, because these mothers have not been exposed to oxytocin release during labor Velandia, These mothers do not have any oxytocin release since there was no labor.
As described in detail above, oxytocin released from the PVN into the NTS increases the release of oxytocin, in response to somatosensory stimulation, by facilitating the function of incoming sensory nerves involved in oxytocin release for references see above. If, however, these mothers are given an infusion of exogenous oxytocin after birth postpartum , the effect of skin-to-skin contact is restored and the mothers do release oxytocin in response to skin-to-skin contact and suckling Velandia et al.
Another consequence of elective Cesarean section is that the psychological maternal adaptations normally induced after labor, e. Oxytocin infusions postpartum, restore the maternal psychological adaptations Velandia, It is well known, since the work of Klaus and Kennell, that close contact between mothers and infants immediately after birth, i. Both mothers and infants having had 2 h of skin-to-skin contact after birth were shown to interact better with each other and the infants were shown to handle stress better 1 year later, than did mothers and infants that were separated after birth.
The immediate oxytocin promoted or facilitated effects on social interactive behaviors and stress reactivity that was induced during skin-to-skin after birth became sustained and expressed in a more developed or mature way 1 year later Bystrova et al. Data from animal experiments support these findings and also extend the results from a mechanistic point of view. If newborn rats are exposed to extra sensory stimulation of the skin by intense maternal licking or by brushing , the animals become more social and less anxious and stressed as adults Francis et al.
The physiological and behavioral changes induced by tactile stimulation in the newborn rats are associated with changes in the function of several transmitter systems. The increased levels of social performance and the decreased levels of anxiety are linked to an increased amount of oxytocin receptors in the amygdala Francis et al.
Reduced levels of CRF in the PVN of the hypothalamus and an increased number of alpha 2-adrenoreceptors in the NTS and the LC also contribute to the long-term anti-stress pattern induced by tactile stimulation in the newborn period. The increased function of alpha 2-adrenoreceptors is caused by oxytocin released into the NTS and LC from oxytocinergic nerve fibers emanating from the PVN, which are activated in response to tactile stimulation.
In this way, as described before, stress reactions are blunted because the activity of noradrenergic fibers originating in the NTS and LC is reduced.
Interestingly, the more tactile stimulation rat pups had been exposed to postnatally, the higher the amount of alpha 2-adrenoreceptors were in the adults rats Caldji et al. All the long-term effects described above, caused by tactile stimulation seems to be induced by early epigenetic programming Cameron et al.
It is well known that early exposure to stress, during pregnancy or in early life, may lead to lifelong sensitivity to stress and stressors and also to an inhibition of social interactive behaviors Anacker et al.
This pattern is, e. The data described in this article suggests that also a partly opposite effect pattern exists, which is induced by non-noxious somatosensory stimulation. This pattern can be learnt or imprinted early in life and is linked to high levels of friendly social interaction and low stress reactivity. This system is linked to a moderate activity in the HPA-axis and in the sympathetic nervous system and in addition to a high activity in the parasympathetic nervous system.
The long-term effects of skin-to-skin contact described above, i. An interesting question is therefore, whether secure attachment is associated with a well-functioning oxytocinergic system? If so, stimulation of oxytocin release in response to skin-to-skin contact or other types of closeness, especially if induced repeatedly and early in life, could be an important mechanism, through which secure attachment is developed.
Further on just the thought of or the mental image of the mother may be enough to trigger oxytocin release in the child. In conclusion the more closeness, physical as well as mental, a child receives the more the function of the oxytocin system will be stimulated.
The findings in some studies of higher oxytocin levels in individuals with secure attachment than in those with insecure attachment support the role of a well-functioning oxytocin system in individuals with secure attachment Tops et al. In addition administration of oxytocin spray has been demonstrated to enhance the experience of attachment security Buchheim et al. From the perspective of this article it is of particular interest that some individuals with insecure attachment do not only have lower levels of oxytocin than those with secure attachment, they also have an increased risk of developing certain symptoms and diseases.
Individuals having insecure attachment more often report high levels of anxiety, depression and stress than those who are securely attached for a review, see Julius et al. In addition they have an increased risk of pain and inflammation Davies et al. For example women with insecure attachment more often have pain during labor and during intercourse dyspareunia; Granot et al. As oxytocin released within the brain from nerves emanating from the PVN is involved not only in the regulation of social interaction and anxiety, but also of pain and inflammation, a low function in the oxytocinergic system could underlie or at least contribute to the expression of these symptoms in individuals with insecure attachment for references, see above.
In addition a disturbed function of the oxytocin system has been demonstrated in certain medical conditions, which may in fact to a certain extent overlap with insecure attachment. Low levels of oxytocin have, e. Also some pain syndromes such as fibromyalgia and recurrent abdominal pain in children are associated with low levels of oxytocin Alfven et al. In addition, previous experience of traumatic events is associated with an increased incidence of low oxytocin levels or stress related reduction of oxytocin levels Pierrehumbert et al.
It is, however, important to mention that low and high levels of oxytocin could not always be categorized as bad or good. As peripheral oxytocin levels and also the effects of oxytocin are influenced by many different factors, other relationships also exist Bartz et al.
For example, as will be described more in detail later in this chapter, oxytocin levels display two peaks during encounters with other individuals, one when meeting and approaching the other individual and one when being in close contact and receiving sensory stimulation by the other individual. The first peak is linked to arousal and an increased activity in the stress axis and the second peak is linked to decreased stress levels Rehn et al. As mentioned above oxytocin levels may rise as a consequence of closeness between mothers and infants, and when they are bonded or attached to each other, oxytocin levels rise also when they just see, hear or even think of each other Swain et al.
A similar reaction takes place in adults as warm partner contact has been demonstrated to be linked to oxytocin release and anti-stress effects. In fact oxytocin may be released, when individuals of both sexes and all ages touch each other, given that the relationship is perceived as positive.
Oxytocin may even be released by seeing, hearing or by merely thinking of the other beloved person Carter and Keverne, ; Grewen et al. In stable long-term relationships oxytocin levels may display a chronic rise and some studies show that basal oxytocin levels are higher in individuals who live together.
The high levels of oxytocin are most likely a consequence of cohabitation, but it can of course not be excluded that individuals who have high oxytocin levels more often choose to cohabitate than those with low oxytocin levels Humble et al. Many studies demonstrate that the health profile of people, who live in good relationships, is better than for those who live alone.
They, e. They have less infections and the risk for some types of cancer is reduced. People who live in good relationships may even look younger and live longer than those, who live alone. It is however of importance to note that the relationship should be warm and of a good quality for these positive health consequences to develop.
Relationships characterized by fear and distrust, may give rise to an increased risk of cardiovascular disease in particular in women Seeman, ; Uchino and Garvey, ; Christenfeld and Gerin, ; Blom et al. Sexual relationships are linked to oxytocin release. Data from both animals and humans demonstrate that large amounts of oxytocin are released in response to sexual activity both in females and males. In humans the peak of oxytocin seems to coincide with orgasm Carmichael et al.
Oxytocin has been demonstrated to promote sexual functioning and has been shown to increase the drive for sex, to facilitate ejaculation and transport of eggs, and the experience of orgasm in both men and women.
In addition, oxytocin has been demonstrated to be linked to bonding between individuals induced by sex but also to the reduction of anxiety and increased wellbeing and calming induced by intercourse Carmichael et al.
Long-term studies suggest that individuals with a good sex life are healthier and live longer, than those without it. It is likely, that the oxytocin release during sex contributes to the health promoting effects, but the effects could also be indirectly mediated by the strengthening of the relationship and of the bonding that is often the consequence of a good sex life Brody, Oxytocin levels peak significantly in both dog owners and dogs when they interact and in particular when the owner strokes and caresses her dog Odendaal and Meintjes, ; Miller et al.
Oxytocin is however also released when the dogs see and want to approach the owner. These two separate phases of oxytocin release are described in the following experiments.
Dogs were exposed to a short separation from a familiar person and then reunited with this person after 30 min. When the familiar person returned, the mere sight of her induced a peak shaped oxytocin release as well as an increase in cortisol levels in the dogs.
After the reunion the familiar person either ignored the approaching dogs or had verbal contact without touching them, or the familiar person both talked to and had physical contact with the dogs. Only in the third scenario, where the dogs received physical contact from the familiar person, did oxytocin levels continue to be elevated.
In addition, cortisol levels decreased in these dogs demonstrating that oxytocin release induced by tactile stimulation is associated with anti-stress effects. In the two other scenarios where the familiar person did not touch the dogs, because they ignored them or just had verbal contact with them, no further oxytocin was released and the dogs cortisol levels remained high Rehn et al.
In another experimental setting, children with severe attachment problems were exposed to a stressful task. Cortisol levels were measured in saliva in order to monitor the stress reaction. When these children performed the stress test they were allowed support either by a trained and emphatic human, a friendly therapy-dog dog or a stuffed toy dog. The results showed that salivary cortisol, was significantly lower in the children, who had a friendly therapy-dog as a companion during the stress test, compared to the children who had a friendly human or a toy dog.
In addition, the lowering of cortisol levels seen in the children who had a dog present during the stress test correlated with the amount of physical contact between the child and dog Beetz et al. The finding that humans failed to calm the child and lower their cortisol levels may be related to the fact that the children with severe attachment problems were too afraid of humans in order to receive any support from them. In contrast, interaction with the living therapy-dog was accompanied by decreased cortisol levels.
As stroking releases oxytocin and since oxytocin decreases the release of cortisol, the decrease in cortisol levels observed in the boys that were physically interacting with the dogs are likely to be secondary to a release of oxytocin triggered by touch. The stuffed dog did not give rise to the same stress buffering effects as the real dog.
This may be due to the fact that just seeing and approaching the friendly therapy-dog triggers a peak of oxytocin in the child just as it did in dogs when they were reunited with their familiar person, as described above. Taken together these two experiments regarding interaction between humans and dogs demonstrated that interaction between the two individuals comprises of two separate phases of oxytocin release. If the approach phase is followed by physical interaction a second phase of oxytocin release is activated.
This second phase of oxytocin release is associated with a reduction of stress levels, e. Physical interaction with a toy dog did not result in the same stress reduction as a consequence of oxytocin release , as did the real dog. This is probably due to the fact that the stuffed dog was not as attractive as the real dog and in the absence of a joyful approach phase no oxytocin release was induced.
In contrast the real dog triggered an initial pulse of oxytocin. This situation is analogous to the previous observations of presence or absence of oxytocin release in response to skin-to-skin contact depending on the type of birth, as described above. During normal vaginal labor oxytocin is released and oxytocin is released following skin-to-skin contact after birth.
In the absence of oxytocin release during birth, as, e. However, this effect was restored in mothers who had received infusions of exogenous oxytocin postpartum.
This two phase model of oxytocin release during interactions as described above is most likely not only related to interactions between dogs and humans but is of general importance and is most likely also present during interaction between humans in different situations where, e. As described above, previously induced oxytocin release into the NTS opens up for further oxytocin release in response to tactile stimulation and closeness.
It should be noted that this two phase release of oxytocin occurs as long as the individual is experiencing the situation in a positive way. If the situation is experienced as stressful or threatening the release of oxytocin will be absent.
Stroking of a dog has been shown to significantly reduce blood pressure and cortisol levels Odendaal and Meintjes, ; Miller et al. In addition, pet ownership is associated with lower blood pressure, serum triglycerides, and cholesterol levels Allen et al.
Patients suffering from a heart attack had significantly higher 1-year survival rates if they had a pet, compared to those without pets, and dog owners are 8. Pets also have a positive impact on the ability to cope with chronic conditions and on the course and treatment of illness such as heart disease, dementia, and cancer Johnson et al.
Recovery of hospitalized children has been facilitated by interaction with companion animals Walsh, and the animals also ease suffering and anxiety at the end of life for those in palliative and hospice care Geisler, In addition, children having a dog present in their classroom display increased social competence and concentration Hergovich et al.
Studies investigating the effects of interaction between dog owners and their dogs in a more long-term perspective indicate that there is a mutual relationship between owners and their dogs, where positive or absence of negative aspects of the relationship are linked to higher oxytocin levels in both species. In addition, frequent sensory interaction between dog-owners and their dogs was associated with higher oxytocin levels in both species.
The release of oxytocin normally occurring in response to closeness in good relationships can to a certain extent be mimicked by massage and stroking of the skin. Indeed, treatment with massage is linked to oxytocin release.
The massage treatment is accompanied by several positive effects. During a massage session levels of anxiety are decreased, the perception of wellbeing is increased and that of pain decreased. Moreover, both blood pressure and cortisol levels are lowered.
Repeated massage treatments are associated with long-term expression of all these effects Field, , Massage also increases the ability for friendly interaction, and may even be used to resolve marital conflicts Ditzen et al. Oxytocin, released into the brain in response to the massage, should be an important mediator of the above, mentioned effects.
Food intake is also associated with oxytocin release and several mechanisms are involved in the oxytocin release induced by ingested food. When food touches the oral mucosa oxytocin is released following activation of touch receptors in the oral cavity and when the ingested food reaches the gastrointestinal tract, the gut hormone cholecystokinin CCK is released from the duodenum in particular in response to proteins and fat.
Sensory fibers of the vagal nerves are then activated by CCK. Suckling is also linked to oxytocin release as the act of suckling per se induces oxytocin release by activation of touch receptors in the oral cavity Lupoli et al. Also the attachment between infant and mother may in a primitive sense be linked to oxytocin release caused by suckling. It is even possible that the dependency of other types of suckling related behaviors, e. As eating has apparent rewarding and also relaxing effects, it represents an important pathway to achieve wellbeing and stress relief and eating or overeating for self-soothing is very common.
Unfortunately overweight and obesity are long-term consequences of overeating. A common denominator for breastfeeding, skin-to-skin contact between mothers and infants, warm interactions with or without sex between adults, as well as tactile interaction with a friendly or beloved dog and even massage or other types of tactile treatments which represent different kinds of relationships with other living beings, is that they are accompanied by oxytocin release through activation of sensory nerves.
Thereby a number of oxytocin mediated effects, such as increased social interactive behaviors, wellbeing, pain relief and anti-stress effects are activated. These situations linked to sensory stimulation and oxytocin release are also in a long-term perspective linked to good mental and physical health.
Skin-to-skin contact between mothers and infants is linked to increased social interaction and calm. In addition, closeness in early life may promote the development of secure attachment. Adult individuals with secure attachment display less anxiety and depression, less pain and inflammation and a reduced risk for cardiovascular disease. A similar positive effect spectrum has been demonstrated for adult individuals, who are engaged in warm and positive relationships including having a good sex life, and they also live longer.
Interestingly the same positive health pattern emerges in individuals having a pet, e. Dog owners seem to be protected from certain types of stress related diseases such as cardiovascular diseases and have lower blood pressure. Taken together, positive relationships irrespective of age and sex in particular if they involve closeness serve to create wellbeing and reduce stress levels on an everyday basis. Some individuals may prefer to relate with animals rather than relating to humans and a good relationship with a dog that involves physical contact seems to be an efficient way to achieve wellbeing, stress relief, and health promoting effects.
These types of everyday interactions serve as positive self-soothing behaviors. In the absence of close and well-functioning social relationships with humans or dogs, alternative pathways may be used to achieve wellbeing and stress relief. Interestingly massage or other types of tactile interventions give rise to similar effect spectrums as the positive interactions listed above and can therefore be used to increase wellbeing, reduce anxiety and stress levels and increase social interactive behaviors.
Also yoga, different types of relaxation techniques as well as physical exercise is used by many people to achieve such positive effect. The calming and in a broad sense satisfying effects obtained after food intake are available to everybody.
To use ingestion of food as a way to feel good and to reduce stress levels is very common in our time, and may result in overeating, and obesity. The difficulties in breaking too generous feeding habits may in part be due to an oxytocin mediated bonding to the food. Similar mechanisms may be involved in smoking and even ingestion of alcohol. The activity of the function of the oxytocin system differs between individuals, too much or too little oxytocin may be secreted and oxytocin receptors may be deficient.
Such differences may be of genetic or epigenetic origin. Individuals, who for various reasons have a low function in their oxytocin system, may have an insecure type of attachment, have problems with relationships or feel depressed or anxious for other reasons, may feel a stronger need than others to improve their mood and to relieve feelings of stress, tension or pain.
Different individuals use different routes to reach these goals. Some people indulge in too much sex, others eat too much. Both these behaviors will in the long run lead to negative effects regarding the ability to form positive relationships or to retain a normal weight. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Agren, G. The act of nursing or suckling is relayed within a few milliseconds to the brain via a spinal reflex arc. These signals impinge on oxytocin-secreting neurons, leading to release of oxytocin. Watch someone milk a cow, even with a machine, and what you'll see is that prior to milking, the teats and lower udder are washed gently - this tactile stimulation leads to oxytocin release and milk ejection.
A number of factors can inhibit oxytocin release, among them acute stress. For example, oxytocin neurons are repressed by catecholamines , which are released from the adrenal gland in response to many types of stress, including fright. As a practical endocrine tip - don't wear a gorilla costume into a milking parlor full of cows or set off firecrackers around a mother nursing her baby. Both the production of oxytocin and response to oxytocin are modulated by circulating levels of sex steroids.
The burst of oxytocin released at birth seems to be triggered in part by cervical and vaginal stimulation by the fetus, but also because of abruptly declining concentrations of progesterone. Another well-studied effect of steroid hormones is the marked increase in synthesis of uterine myometrial oxytocin receptors late in gestation, resulting from increasing concentrations of circulating estrogen.
Some have proposed a correlation between the concentration of oxytocin and the intensity of orgasm. When oxytocin enters the bloodstream, it affects the uterus and lactation, but when it is released into certain parts of the brain, it can impact emotional, cognitive, and social behaviors.
Brain oxytocin also appears to reduce stress responses, including anxiety. These effects have been seen in a number of species. The participants were all receiving hormone therapy HT following menopause.
Animal studies have found high levels of both stress and oxytocin in voles that were separated from other voles. However, when the voles were given doses of oxytocin, their levels of anxiety, cardiac stress, and depression fell , suggesting that stress increases internal production of the hormone, while externally supplied doses can help reduce stress. Nevertheless, oxytocin does appear to be associated with social behavior, including maternal care, bonding between couples, sexual behavior, social memory, and trust.
Delivering oxytocin through a nasal spray has allowed researchers to observe its effects on behavior. In , research published in Psychopharmacology found that intranasal oxytocin improved self-perception in social situations and increased personality traits such as warmth, trust, altruism, and openness. In , a study published in PNAS suggested that oxytocin may help keep men faithful to their partners, by activating the reward centers in the brain. In , researchers published findings in the journal Emotion suggesting that people saw facial expression of emotions in others more intensely after receiving oxytocin through a nasal spray.
Oxytocin has been proposed as a possible treatment for social phobia , autism , and postpartum depression. Scientists have proposed that it might help improve interpersonal and individual wellbeing, and that it could have applications for people with some neuropsychiatric disorders.
They believe it could help people who avoid social interaction, and those who experience persistent fear and an inability to trust others. Children with autism could benefit from oxytocin, say some researchers. In , a small study suggested that oxytocin levels in the brain affected how 17 children perceived a series of social and non-social images. Oxytocin may also play a role in anger management. Research has indicated that certain polymorphisms of the oxytocin receptor OXTR gene are associated with an increased tendency to react angrily to situations.
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