Where is oxytocin made

About Contact Events News. Search Search. You and Your Hormones. Students Teachers Patients Browse. Human body. Home Hormones Oxytocin. Oxytocin Oxytocin is a hormone that acts on organs in the body including the breast and uterus and as a chemical messenger in the brain, controlling key aspects of the reproductive system, including childbirth and lactation, and aspects of human behaviour.

Alternative names for oxytocin Alpha-hypophamine; manufactured versions — syntocinon and pitocin both synthetic oxytocin ; carbetocin an analogue of oxytocin with similar structure What is oxytocin? In the brain, oxytocin acts as a chemical messenger and has an important role in many human behaviours Oxytocin Oxytocin is a hormone that acts on organs in the body including the breast and uterus and as a chemical messenger in the brain, controlling key aspects of the reproductive system, including childbirth and lactation, and aspects of human behaviour.

How is oxytocin controlled? What happens if I have too much oxytocin? What happens if I have too little oxytocin? Thus oxytocin reaches several important areas in the central nervous system CNS , which are involved in the regulation of social interactive behaviors, fear, aggression perception of pain, calm, wellbeing, and stress reactions by modulating the activity of the HPA-axis and the sympathetic and parasympathetic nervous system.

Oxytocin can also be released from dendrites of the oxytocinergic neurons in the SON and PVN and then by diffusion and volume transmission reach distant locations in the brain to induce oxytocin mediated effects. For example such effects might occur when oxytocin is released in high amounts as, e. During these occasions high amounts of oxytocin is released in parallel both into the periphery and within the CNS Keverne and Kendrick, Figure 1.

Schematic illustration of how oxytocinergic neurons within the PVN project to some important regulatory areas in the CNS. Oxytocin may act via one or several of these different mechanisms at the same time and also different combinations of oxytocin mediated effects might be activated.

In this way separate oxytocin effects are integrated into broader effect patterns. As will be described in more detail below, when oxytocin release is induced by low intensity somatosensory stimulation, the anti-stress effect pattern becomes particularly prominent.

The amount of oxytocin receptors and their binding properties are of course also of fundamental importance for the effects of oxytocin. Here both sex steroids and glucocorticoids play an important role since they both have the capacity to influence the expression of oxytocin receptors as well as the binding of oxytocin to receptors in the brain Schumacher et al.

Not all oxytocin-mediated effects are blocked by antagonists directed toward the uterine type of oxytocin receptor, e. The reason is that oxytocin is metabolized and degraded into several smaller cyclic and linear oxytocin fragments de Wied et al. A C-terminal fragment has been linked to calming, anti-stress, and growth promoting effects of oxytocin Petersson et al. Variants of the oxytocin receptor gene have been demonstrated, some of which have been associated with different capabilities to recognize facial expression Kumsta and Heinrichs, Some variants of the oxytocin receptor gene are also more prevalent in individuals with schizophrenia and autism Montag et al.

The half-life of oxytocin in the circulation of humans is 30 min De Groot et al. A similar half-life has been demonstrated in the cerebrospinal fluid, but might be even longer in different parts of the brain Jones and Robinson, The half-life of the oxytocin fragments is not known, but may be longer than that of the mother molecule. Oxytocin may also be transported across the BBB by specific carrier proteins Jones and Robinson, Oxytocin exerts some of its actions by modulating the function of other signaling systems.

It, e. As will be discussed in detail below, the effect of oxytocin to inhibit the activity of noradrenergic neurons in the CNS is of great importance for the anti-stress effects induced by oxytocin. Administration of oxytocin gives rise to many different effects. Different kinds of social interactions are promoted including mother—infant interaction and bonding between mother and infant Keverne and Kendrick, Oxytocin may also induce powerful anti-stress effects by reducing the activity of the HPA-axis and of some aspects of the sympathetic nervous system, for example the activity of the cardiovascular system may be decreased.

It should be noted that when oxytocin is released by threatening situations or an unfamiliar environment it may induce powerful protective and aggressive effects, which are also linked to an increased activity in the HPA axis and of the sympathetic nervous system Bosch et al. When oxytocin is administered repeatedly [subcutaneously SC or intracerebroventricularly ICV ] long-term effects are induced. For example blood pressure and cortisol levels are decreased and pain threshold as well as the release of gastrointestinal hormones such as insulin is increased for several weeks after the last administration of oxytocin Petersson et al.

These sustained effects are due to the fact that oxytocin influences the production of neurotransmitters or the function of their receptors in a long-term way. Repeated administration of oxytocin, e. The long term anti-stress effects caused by repeated exposure to oxytocin are linked to a changed function of mineralocorticoid receptors MR and glucocorticoid receptors GR in the hippocampus, to decreased production of corticotrophin releasing factor CRF in the PVN, but above all to a decreased function of central noradrenergic transmission by an increased function of inhibitory alpha 2-adrenoreceptors.

Such receptors, located presynaptically on noradrenergic neurons emanating from the LC and NTS, exert an inhibitory function on the release of noradrenaline, which leads to decreased stress levels and reactivity to stress Petersson et al. Other effects of repeated oxytocin administration are increased rates of learning and wound healing Petersson et al. If oxytocin is given repeatedly to rats in the postnatal period, an effect pattern similar to the one seen in adult rats is induced, the difference being that the effects might become even life-long.

A decrease in blood pressure, in levels of corticosterone and an increase in nociceptive thresholds may be seen. In addition the function of central alpha 2-adrenoreceptors is increased Sohlstrom et al. In humans, intranasal administration of oxytocin has been shown to stimulate certain aspects of social interaction, e.

Also the reactivity of the amygdala may decrease, thereby reducing fear and facilitating friendly social interactions Domes et al. It also causes anxiolytic and anti-stress effects Heinrichs et al.

Oxytocin has also been shown to cause wellbeing and to decrease the experience of pain Ohlsson et al. In other clinical trials oxytocin has, e. It has also been shown to facilitate withdrawal from alcohol Pedersen et al. It is of importance to mention that the effect patterns induced by repeated administration of oxytocin by nasal, by ICV, SC, intravenous IV injections or by stimulation of endogenous oxytocin release via stimulation of sensory nerves are not always the same.

For example, repeated administration of oxytocin spray to mice has been shown to result in down regulation of oxytocin receptors and to impairments in behavioral development in mice Bales et al. Most likely oxytocin released in response to repeated stimulation of sensory nerves results in a more physiological and sustainable effect pattern than does any form of repeated pharmacological administration of oxytocin.

The release of oxytocin can be stimulated by hormones such as estrogen. In addition oxytocin can be released in response to various types of sensory stimulation. When oxytocin is released in response to pain and stressful stimuli it may play a role in certain types of stress, and thereby it may also act to dampen stress reactions Neumann, The non-noxious type of somatosensory stimulation is of particular importance for the hypothesis presented in this article, i.

The most well-known situations, which are related to oxytocin release, are labor and breastfeeding, when oxytocin stimulates uterine contractions and milk ejection respectively. Oxytocin can, however, also be released following activation of other sensory nerves originating from, e. Figure 2. Figure 3. Schematic illustration showing how afferent nerves from different parts of the body stimulate oxytocin release. Low intensity non-noxious stimulation of somatosensory nerves in conscious or unconscious rats, results in increased social behavior, increased pain threshold, profound anti-stress effects, such as a decrease in blood pressure and in cortisol levels.

In addition the function of the gastrointestinal tract is increased Araki et al. The exact nature of sensory nerves, which mediate the effects of non-noxious stimulation, is not known. Myelinated somatosensory fibers mediating the sense of touch may be involved, but a more likely candidate to this effect is the unmyelinated CT fiber afferents.

Oxytocin is not only released into the circulation, but also into the brain. In fact many of the physiological effects induced by non-noxious sensory stimulation are partly mediated by oxytocin. The increase of pain threshold induced by certain types of non-noxious sensory stimulation, e.

These fibers are, as described above, involved in the control of autonomic nervous tone. Also many physiological effects induced in the brainstem area brainstem reflexes in response to sensory stimulation, are modulated by oxytocinergic fibers, which originate in the PVN and project to the NTS. The oxytocin released in the NTS exerts a further important effect. As mentioned above, all types of sensory stimulation, involved in oxytocin release, relay in the NTS. Oxytocin released into the NTS from nerves originating in the PVN facilitates the transmission of sensory neurons in the NTS, which are associated with oxytocin release.

In this way a feed-forward stimulation of the oxytocin release, induced by sensory stimulation, is provided Burbach et al. Finally oxytocin, in particular after repeated administration, stimulates presynaptic alpha 2-adrenoreceptors on noradrenergic neurons originating in the NTS and LC. The firing of the neurons originating in the LC is decreased by repeated oxytocin administration. In addition administration of oxytocin increases the amount of alpha 2-adrenoreceptors in some other areas of the brain, such as the hypothalamus, the amygdala and the NTS Petersson et al.

As the alpha 2-adrenoreceptors inhibit the function of the noradrenergic neurons, which are linked to stress reactions, the oxytocin mediated increase in alpha 2-adrenoreceptor function will result in decreased stress levels and in decreased reactivity to stress. In addition the oxytocin released into the brainstem by non-noxious sensory stimulation will potentiate actions of local brainstem reflexes and also facilitate the function of sensory neurons mediating oxytocin release in the NTS for references see above.

Oxytocin has the capacity to stimulate its own release in several ways. As oxytocin is released from the dendrites of the oxytocin producing cells, a local feed forward system is activated Ludwig and Leng, There is accumulating evidence that also circulating oxytocin can stimulate oxytocin release from the SON and PVN by activation of oxytocin receptors located on peripheral sensory nerves, such as the pelvic and the hypogastric nerves Jonas et al.

In addition oxytocin, released from the oxytocinergic neurons projecting to the NTS, may via activation of oxytocin receptors located on sensory neurons which project to the NTS, facilitate the function of these neurons thereby increasing oxytocin release Burbach et al. It is well established that the HPA-axis regulates the secretion of cortisol from the adrenal glands.

First CRF, produced in and released from neurons within the PVN of the hypothalamus, stimulates the secretion of ACTH adrenocorticotropic hormone from the anterior pituitary into the circulation.

Circulating ACTH in turn stimulates cortisol secretion from the adrenal glands. The activity of the noradrenergic neurons in the LC is influenced by the amygdala-hippocampal systems and the activity of the noradrenergic neurons emanating from the NTS by afferent nerves mediating noxious stimuli Araki et al. When the amygdala-hippocampal system is activated in response to a stressor, neurons, which project from the amygdala to the LC, are activated.

Van Bockstaele et al. Consequently the noradrenergic neurons in the LC are activated and noradrenaline is released, e. Stimulation of sensory nerves in response to dangerous or noxious sensory stimuli represents an alternative way by which the CRF secretion in the PVN and thereby the HPA-axis can be activated. In this situation noradrenergic neurons emanating in the NTS are activated by the noxious sensory stimulation and then noradrenaline released from these neurons, in turn stimulates the release of CRF Araki et al.

Oxytocin may antagonize the activity of the stress axis in multiple ways. It is well established that oxytocin released from nerves within the hypothalamus and in the anterior pituitary inhibits CRF and ACTH secretion respectively and that circulating oxytocin may inhibit cortisol secretion directly from the adrenals Stachowiak et al. Oxytocin may be released to antagonize stress reactions in three principally different ways:. Oxytocin is released in response to pleasant mental experiences.

Such a release of oxytocin may, e. As oxytocin is released from neurons emanating in the PVN stress reactivity will be dampened in multiple ways. The activity in the HPA-axis will be reduced by oxytocin according to the pattern described above.

In addition, as oxytocin is released from neurons within the amygdala, the reactivity to fear and stress is dampened and consequently the activity of neurons that project from the amygdala to the LC will be decreased see above. As a consequence of a less intense stimulation of the function in the LC, the release of noradrenaline from the noradrenergic neurons emanating in the LC declines. Also the activity in other areas involved in stress regulation and which are receiving noradrenergic projections from the LC will be decreased.

The activity in the LC and NTS will of course also be decreased by oxytocinergic neurons projecting directly to these areas. Oxytocin is also released in response to activation of somatosensory nerves, which mediate non-painful and pleasant non-noxious information, e.

Oxytocin may in response to non-noxious stimulation be released into the hypothalamus to reduce the activity in the HPA-axis and into the amygdala to decrease the reaction to stress and fear and thereby the activity of the noradrenergic neurons in the LC, which control the activity of the HPA axis.

In addition, oxytocin released from neurons projecting from the PVN to the LC and NTS in the brainstem, may decrease stress reactions by reducing the activity in the stress related noradrenergic neurons emanating from these nuclei. The effect of oxytocin released from the neurons that project from the PVN to the NTS involves activation of alpha 2-adrenoreceptors, which inhibit the function of the noradrenergic neurons in the LC and NTS.

In this way the secretion of CRF in the hypothalamus and the activity of the HPA- axis are further decreased, as described in detail above. Taken together oxytocin release induced by non-noxious somatosensory stimulation inhibits stress by direct actions in the amygdala, the hypothalamus, the LC and the NTS. In addition, oxytocin may also be released by mental and sensory stimuli that are perceived as stressful. In this case oxytocin is activated in parallel with the stress system and the role of oxytocin in these situations may be to dampen stress responses and facilitate coping behaviors Neumann, Figure 4.

Schematic illustration of different effects of oxytocin released from parvocellular neurons in the brainstem. Non-noxious stimulation of afferent sensory nerves results in release of oxytocin from the PVN. Noxious and non-noxious stimulation of afferent sensory nerves result in activation of sympathetic and parasympathetic neurons in the brain stem and spinal cord autonomic centra, AC. Oxytocin released from oxytocinergic neurons originating from the PVN and projecting to areas in the brainstem and spinal cord involved in the control of autonomic nervous tone e.

In addition it reinforces and facilitates effects caused by shorter brain stem projections. In this way hypothalamic reflexes controls and modulates the activity of the shorter brainstem reflexes. Oxytocin released from oxytocinergic neurons originating from the PVN and projecting to the NTS facilitates the function of afferent neurons involved in the release of oxytocin, thereby facilitating oxytocin release. It also activates alpha 2-adrenoceptors on noradrenergic fibers innervating CRF neurons in the PVN, thereby decreasing stress reactivity.

In this way non-noxious somatosensory stimulation promotes oxytocin release and oxytocin mediated effects, but counteracts CRF and VP linked effects. The oxytocin release caused by non-noxious somatosensory stimulation gives rise to particularly pronounced anti-stress effects because:.

As mentioned above it is well known that oxytocin is released during labor and breastfeeding to induce uterine contractions and milk ejection. Still the concomitant effect pattern differs between the two situations.

During labor the pulsatile oxytocin release is associated with high stress levels and cortisol levels are elevated and blood pressure is high in order to make the hard work of labor and uterine contractions possible.

During breastfeeding, on the other hand, cortisol and blood pressure fall in response to each suckling episode Nissen et al. Oxytocin is also released into the brain during labor and breastfeeding.

Oxytocin thereby induces pain relief during labor and also helps to adapt the mothers to the role of motherhood by increasing social skills and by decreasing anxiety Nissen et al. Research has shown that mothers, who have breastfed for several weeks have lower basal, systolic and diastolic, blood pressure Jonas et al. They are also calmer and more socially inclined Nissen et al. These long-term adaptive changes are most likely induced by a changed function in other signaling systems as a consequence of the repeated exposure to endogenous oxytocin that occurs during breastfeeding.

As mentioned above repeated administration of oxytocin changes the function of several types of signaling systems in the brain in a long-term way. The findings of a reduced risk for certain kinds of cardiovascular disease and also of diabetes type 2 many years after the end of breastfeeding in mothers who have breastfed several children for long periods of time supports the existence of a link between repeated exposure to endogenous oxytocin and long-term anti-stress and health promoting effects Lee et al.

An increase in the function of alpha 2-adrenoreceptors may play a pivotal role in these health promoting effects by decreasing stress levels and stress sensitivity. Oxytocin cannot only be released by the suckling stimulus but also by stimulation of cutaneous nerves, As mentioned previously oxytocin has in experiments performed on rats been demonstrated to be released in response to several types of non-noxious sensory stimulation, such as touch, massage, stroking, warm temperature, and low intensity electrical stimulation.

Stimulation of cutaneous sensory nerves is an important and common aspect of many types relationships, e. Therefore oxytocin release and oxytocin mediated effects caused by pleasant sensory stimulation should play an important role in all these types of relationships. The release of oxytocin and the pattern of oxytocin mediated effects induced during skin-to-skin contact between mother and infant after birth will be described in some detail, as this type of interaction could be regarded as archetypal representation of interactions between humans or between humans and animals, involving close physical contact.

Oxytocin is for example released into the maternal circulation in response to skin-to-skin contact between mother and infant immediately after birth. 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. The acute effects of intranasal oxytocin administration on endocrine and sexual function in males.

Psycho neuro endocrinology. Male anorgasmia treated with oxytocin. J Sex Med. Carter CS. Developmental consequences of oxytocin. Physiol Behav. Anderson PO, Valdes V. A critical review of pharmaceutical galactagogues. Breastfeed Med. Anderson—Hunt M, Dennerstein L. Increased female sexual response after oxytocin. The role of oxytocin in Relation to female sexual arousal. Gynecol Obstet Invest.

Afferents originating from the dorsal penile nerve excite Oxytocin cells in the hypothalamic paraventricular nucleus of the rat. Brain Res. Changes in Oxytocin and vasopressin secretion during sexual activity in men. Stage—related differences in rat seminiferous tubule contractility in vitro and their response to Oxytocin. J Endocrinol. Testicular Oxytocin: effects of intratesticular Oxytocin in the rat. Neumann ID, Landgraf R.

Advances in vasopressin and oxytocin--from genes to behaviour to disease. Prog Brain Res. Lukas M, Neumann ID. Oxytocin and vasopressin in rodent behaviour related to social dysfunctions in autism spectrum disorders.

Behav Brain Res. Polymodal dose—response curve for oxytocin in the social recognition test. Endogenous oxytocinis involved in short-term olfactory memory in female rats. Oxytocin mediates rodentsocial memory within the lateral septum and the medial amygdaladepending on the relevance of the social stimulus: male juvenile versus female adult conspecifics.

A conditional knockout mouse line of the oxytocin receptor. Induction of maternal behavior in virgin rats after intracerebroventricular administration of oxytocin. Insel TR. A neurobiological basis of social attachment. Am J Psychiatry. Evidence for a neuroendocrinological foundation of human affiliation: plasma oxytocin levels across pregnancy and the postpartum period predict mother-infant bonding. Psychol Sci. Maternal and paternal plasma, salivary, and urinary oxytocin and parent-infant synchrony: considering stress and affiliation components of human bonding.

Dev Sci. Legros JJ. Inhibitory effect of oxytocin on corticotrope function in humans: are vasopressin and oxytocin ying-yang neurohormones? Effects of oxytocin on the function and morphology of the rat adrenal cortex: in vitr o and in vivo investigations.

Res Exp Med Berl. Behavioral consequences of intracerebral vasopressin and oxytocin: focus onlearning and memory. Neurosci Biobehav Rev. Gibbs DM. Dissociation of oxytocin, vasopressin, and corticotropin secretion during different types of stress. Life Sci. Oxytocin increases trust in humans. Plasma oxytocin levels and anxiety in patients with major depression.

Selective serotonin reuptake inhibitors and their effects on relationship satisfaction. The family journal. A relationship between Oxytocin and anxiety of romantic attachment. Clin Pract Epidemiol Ment Health. Oxytocin: the Great Facilitator of Life. American Psychiatric Association. Oxytocin, vasopressin and pair bonding: implications for autism. Genes controlling affiliative behavior as candidate genes for autism. Biol Psychiatry. Oxytocin increases retention of social cognition in autism.

Intranasal Oxytocin improves emotion recognition of youth with autism spectrum disorders. Biol psychiatry. Promoting social behaviour with Oxytocin in high functioning autism spectrum disorders. The environment and schizophrenia. Bujanow W. Hormones in the treatment of psychoses. Br Med J. Psychotropic properties of oxytocin.

Neurosci BehavPhysiol. Elizabeth A Lawson. The effects of oxytocin on eating behaviour and metabolism in human. Nat Rev Endocrinol. Medically reviewed by Michael Weber, M.

What is oxytocin? The love hormone? Oxytocin and emotion Behavioral effects Psychiatric therapy Uses Risks Oxytocin is a hormone and a neurotransmitter that is involved in childbirth and breast-feeding. Oxytocin and emotion. Behavioral effects. Psychiatric therapy. Scientists identify new cause of vascular injury in type 2 diabetes. Adolescent depression: Could school screening help?

Related Coverage. What to know about hormonal imbalances. Medically reviewed by Holly Ernst, P. Eight benefits of crying: Why it's good to shed a few tears. Medically reviewed by Timothy J. Legg, Ph. Does sex provide health benefits?

Medically reviewed by Janet Brito, Ph. What is serotonin, and what does it do? Medically reviewed by Debra Rose Wilson, Ph.