Oxytocin

In lactating breasts, oxytocin causes contraction of the myoepithelial cells surrounding the alveoli and ducts of the mammary gland. Due to this, milk produced under the influence of the hormone prolactin is secreted from the breast. When breastfeeding, oxytocin enters the mammary gland , helping milk pass into the subareolar ducts, from where milk is secreted from the nipples. After a child has absorbed oxytocin from milk, it enters the hypothalamus through the general bloodstream. Influence on the child’s hypothalamus induces hypothalamic neurons to produce oxytocin and promotes a triggering pulse in the production of oxytocin by intermittent shocks. These tremors are the result of a pulsating release of oxytocin from the neurosecretory endings of the nerve in the neurohypophysis .

Uterine Contraction Stimulation

Oxytocin has a stimulating effect on the smooth muscles of the uterus, increases contractile activity and, to a lesser extent, the tone of the myometrium. In small concentrations, oxytocin increases the frequency and amplitude of uterine contractions, in high concentrations it helps to increase uterine tonus, increase and strengthen its contractions (up to tetanic contractions or the development of tonic uterine contracture ). Oxytocin helps to reduce the cervix before birth and during the second and third periods of labor. The release of oxytocin during breastfeeding produces moderate, but often painful contractions during the first weeks of lactation. This serves to coagulate blood in the attachment of the placenta in the uterus. Although in laboratory mice lacking oxytocin receptors, reproductive behavior and childbirth are normal ^[1] . Oxytocin is used after gynecological operations to stop uterine bleeding.

Impact on Sexual Behavior

The effect of oxytocin on human sexual behavior has not been elucidated. At least two studies have found an increase in lymph oxytocin with orgasm in both men and women ^{[2] [3]} . The level of oxytocin in the lymph increases markedly with orgasm during auto-stimulation and becomes higher than usual five minutes after self-excitation ^[4] .

The authors of one study suggested that the effect of oxytocin on muscle elasticity may promote sperm transfer to the egg. Measurements of serum oxytocin in women before and after sexual arousal have confirmed that oxytocin plays an important role in sexual arousal. The same study confirmed that excitation of the genital tract led to an instant increase in oxytocin after orgasm ^[5] . A significant amount of research has been devoted to the study of sexual arousal in men and women. Many scientists believe that women experience deeper orgasms than men, as they have a more complex reproductive, endocrine system with clearly defined cycles, such as menstruation, lactation, menopause and pregnancy. These cycles allow you to evaluate changes in hormones associated with sexual arousal. However, well-known sexologists obtained data on the absence of a difference in the duration and properties of orgasm in men and women ^[6] . Thus, perhaps a disproportionately large number of studies on sexual arousal in women suggest a false, inherent in society view of the female orgasm as something mysterious and exceptional in relation to the male orgasm.

Trust Hormone

Oxytocin causes a feeling of satisfaction, a decrease in anxiety and a sense of calm next to a partner ^[7] . Many studies have proven the connection of oxytocin in human relationships, increasing confidence and reducing fear. This suggests that oxytocin may affect areas of the brain responsible for behavior, fear, and anxiety.

Urinary Decrease

Due to its similarity to vasopressin, oxytocin may slightly decrease urine output. In some animal species, oxytocin can stimulate the excretion of sodium by the kidneys (natriuresis), and in humans, high doses of oxytocin can lead to hyponatremia.

Influence on the heart

Oxytocin and oxytocin receptors are also found in the heart of some rodents, and the hormone can play a role in the embryonic development of the heart by promoting the differentiation of cardiomyocytes. However, a lack of either oxytocin or its receptors in laboratory mice did not lead to heart failure.

Under certain circumstances, oxytocin indirectly interferes with the secretion of adrenocorticotropic hormone and cortisol , and in some situations it can be considered an antagonist of vasopressin ^[8] .

Systemic administration of oxytocin rapidly improves muscle regeneration by increasing stem cell proliferation as a result of activation of the MAPK / ERK signaling pathway in old muscles ^[9] . Given that oxytocin is an FDA approved drug, administering it to patients can be a potentially new and safe way to fight muscle aging.

Oxytocin can be associated with autism and can be an effective treatment for autism and autism-related behavior. Oxytocin treatment has expanded the ability of emotional behavior in adult autistic individuals ^[10] . Two relevant studies in adults, in 2003 and 2007, showed that oxytocin reduced the recurrence of autistic behavior and improved expression of emotions by autists. Recently, through the intranasal administration of oxytocin, an improvement in recognition emotion has been found in children aged 12 years with a diagnosis of autism spectrum disorder. Oxytocin is associated with autism in the sense that autism is determined by the deletion of a gene containing the oxytocin receptor gene (OXTR). Studies involving Caucasians and Mongoloids of China have given grounds for combining OXTR with autism ^{[10] [11]} . After inhaled treatment with oxytocin, autistic patients exhibit more active social behavior. The benefits and side effects of autism treatment with oxytocin have not been thoroughly studied at this time - therefore, oxytocin treatment is recommended. ^{[by whom? ]} , if possible, carried out in conditions relevant to the clinical hospital.

Increased confidence and reduced fear. In the experimental group, subjects administered oxytocin nasally show a “high level of confidence” twice as often as the control group that did not receive oxytocin. Nasal administration of oxytocin showed a decrease in fear, possibly due to suppression of the amygdala (which is considered responsible for fear of communication) ^[12] . Some researchers argue that oxytocin has a general effect on enhancing other social emotions: after intranasal administration of oxytocin, the feeling of envy and gloating increases ^[13] .

Decreased confidence in outsiders and increased cultural prejudice ^[14] .

• The manifestation of generosity through increased confidence ^[15] .
• Some learning and memory functions are weakened after oxytocin administration ^[16] .

Oxytocin also has weak vasopressin-like antidiuretic properties ^[17] .

The effect of oxytocin on the psychoemotional sphere of a person was discovered ^[18] .

Trust Hormone

Oxytocin causes a more favorable disposition to other people, allows you to believe the words of a particular person, but only in certain cases: this applies only to intra-group relations - the person’s attitude to people from other groups does not change for the better or for the worse (the so-called “parochial altruism ”) ^[19] . The hormone is involved immediately after birth in the formation of the mother-child relationship. The manifestation of autism and Williams syndrome depends on the concentration of oxytocin ^[20] .

Influence on men

Other studies conducted on men show that men under the influence of oxytocin improve their ability to understand the mood of other people by facial expression, they begin to look in the interlocutor's eyes more often, and also become more trusting, sometimes even excessively (for example, confidence does not decrease even after cheating). In a normal situation, if a person is told unpleasant news when he looks at someone’s face, then that person will later seem less attractive to him. However, this does not occur in men who have been injected with oxytocin in their nose ^{[21] [22]} .

Studies have also shown that the effect of oxytocin on the male psyche is to selectively increase the sensitivity (susceptibility) to socially significant signals that have a “positive” color. Oxytocin makes men more susceptible to signals and stimuli that carry information important for establishing good relationships (eg, friendships and sexual relations) with other people ^{[18] [22]} . Separate studies on men have shown that the administration of oxytocin reduces egoism in men and increases parochial altruism, that is, strengthens “intragroup love” and trust in “friends”, but does not increase “intergroup hatred” and distrust of “strangers” ^{[19] [23]} .

Studies in rats have shown that males become calmer and bolder after mating with oxytocin ^[22] . In female mammals, oxytocin regulates affection for their cubs.

Effect on alcohol susceptibility

In studies of a group of Australian scientists conducted on rats, it was found that injections of this hormone in large doses make animals immune to alcohol. This may, as experts note, help in the treatment of human alcohol dependence ^[24] .

According to WHO, 1 IU = 1.68 mcg ^[25] IU - International unit , in English sources IU - international units

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