The Most Human Hormone: The Miracle Of Oxytocin

The Most Human Hormone: The Miracle Of Oxytocin
The Most Human Hormone: The Miracle Of Oxytocin

Video: The Most Human Hormone: The Miracle Of Oxytocin

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Video: The Fantastical World Of Hormones With Dr John Wass (Full Biology Documentary) | Spark 2023, January

Almost a century and a half ago, in June 1875, Sir Henry Hallett Dale was born in London, the scientist who discovered one of the most important hormones for us - oxytocin. And at the age of 61, together with Otto Levy, the scientist was awarded the Nobel Prize in Medicine for his scientific work in the field of transmission of nerve impulses, including for oxytocin.

Over the next decades, scientists discovered more and more new features of the effects of oxytocin - and they still do. This hormone, as it turned out, is needed almost everywhere. And not only in the body. One gets the impression that our society and all its complex social ties exist only thanks to this chemical compound.

Is this so and what is interesting about oxytocin, says MedAboutMe.

Hormone Games: From Childbirth to Empathy

The whole story of the discovery of oxytocin is a narrative in which graceful confusion is intertwined with the evolution of amino acids.

It all began in 1909, when Sir Dale was able to isolate an extract of the pituitary gland, which caused contractions of the uterine walls in laboratory cats and stimulated their labor pains. The scientist even named the substance in honor of the stimulation of childbirth: in Greek, oxy means fast, and tokos means childbirth.

More than a century has passed since the discovery of the effect of oxytocin on cats, but today preparations of this hormone are used to stimulate contractions during labor and contraction of the uterus after them. And not only to animals, but also to human women.

And later it turned out that pituitary gland extract not only accelerates labor in cats and affects lactation, but also increases blood pressure in dogs. The extract had to be studied more thoroughly, and it turned out that it contained not one, but two hormones, very similar in structure.

The one that stimulated contractions and milk production turned out to be oxytocin. The second, influencing pressure, was called vasopressin, from vaso - vessel and presso - to press.


Oxytocin production is not limited to the pituitary gland. It is also synthesized in the heart muscle, the wall of the aortic arch, in the smooth muscles of the intestinal walls and even in the gonads - the ovaries and testes. He is needed everywhere - and everywhere he is involved in different processes.

For mammals, in addition to stimulating smooth muscle contraction in the walls of the uterus, it also helps to contract muscle fibers located around the alveoli on the chest, which causes breast milk to separate during lactation.

In male testes, it is needed for the secretion of steroid hormones. Together with testosterone, oxytocin affects sperm motility. In women in the ovaries, it is needed to regulate the formation of the corpus luteum. By the way, he also indirectly affects the secretion of testosterone, controlling the release of luteinizing hormone in the hypothalamus.

Meanwhile, vasopressin also provokes contractions of smooth muscle fibers, but in the walls of blood vessels. In addition (and this function of vasopressin should be in the first place), it is needed to regulate water metabolism in the body, for which this hormone is also called an antidiuretic. Vasopressin is able to induce the processes of the reverse movement of fluids through the membranes of the renal tubules. And if violations occur in the posterior zone of the pituitary gland, where it is secreted, this threatens diabetes insipidus - a pathology in which fluid is rapidly excreted from the body along with urine, since the reverse flow process in the kidneys stops.

Both compounds - oxytocin and vasopressin - have nine amino acids. They differ only in two positions. And even the genes with the code for these hormones are located side by side on the same chromosome.For this reason, scientists believe that at some time in the process of evolution, the hormone was one. And then there was a duplication of the gene, and a new hormone appeared, slightly different from the primary one.

The version is confirmed by the fact that vertebrates have both connections, but invertebrates have only one that performs the functions of both. It is not known which hormone - oxytocin or vasopressin - appeared earlier.

Finally, receptors speak in favor of this version. Those that respond to vasopressin can interact with oxytocin, and vice versa. However, receptors do have preferences, and the ratio of different receptors affects our behavior.

For example, if we talk about cognitive and emotional empathy, the ability to be aware of the feelings of another and empathize, then we owe this not only to oxytocin. No matter how you call it the "hormone of love and empathy," "vasopressin" receptors are also needed for empathy.

Cognitive empathy is more characteristic of men, while emotional empathy is more developed in women. And this, surprisingly, is not only a product of education. It's all about genes.

Women have more oxytocin-prone receptors that provide emotional empathy. And in the male body, there are more people prone to vasopressin, which leads to an increase in the ability to be aware of the feelings of others, making them cognitive empaths.

Oxytocin: Which Hormone Causes Sweet Dreams?

The maximum concentration of oxytocin in the blood is noted at 2-2: 30 am, in the phase of slow sleep. There is the same peak during the day, at about 2 pm. And a person, like a daytime animal, really wants to sleep. As a rule, the maximum secretion of oxytocin is synchronized with the peaks in the production of melatonin and leptin, which also reduce the excitability of the nervous system.

Oxytocin: hormone or neurotransmitter?

Hormones in the bloodstream are carried throughout the body, interact with receptors in target cells and start or slow down various cellular and tissue processes. Hormones are essential for a range of physiological functions, including metabolism.

Neurotransmitters (also called neurotransmitters) are substances involved in the transmission of electrochemical impulses from one neuron to another. It happens like this:

In the interval between neurons there is a place of contact, a synaptic cleft; Neurotransmitters move along the synapse between neurons and transmit impulses from one nerve cell to another.

So oxytocin is not only a hormone, but also a neurotransmitter. True, it performs this function only in the tissues of the brain.

It is interesting!

If oxytocin is injected into some brain tissue by injection, the body will respond with an uncontrollable yawning.

This effect is found when the hormone is injected into the hippocampus, which is responsible for memory and learning, the midbrain - the ventral region of the tire, which secretes the "happiness hormone" dopamine, and into the body of the amygdala, which is responsible for stress and emotional reactions.

And if the oxytocin receptors are blocked, then yawning after the injection does not occur. This fact speaks in favor of the version about the connection between empathy and "contagious yawning" (when at the sight of a yawning person you want to do the same). This version is supported by a number of studies (Autism Research), but still requires additional study.

Instincts, Emotions, Diseases and Human Values

The spectrum of influence of oxytocin is quite extensive. A significant number of pathologies are associated with disturbances in the secretion of this hormone. But what is surprising: often these disorders cause not only physiological problems, but also changes in the psyche of people.

So, pediatricians know the syndrome of neonatal separation of the newborn from the mother. This set of symptoms occurs in infants who have been removed from their mothers immediately after birth and transferred to artificial feeding.In children, there are jumps in body weight gain, respiratory disorders - from oxygen deficiency to hyperventilation of the lungs, accelerated sexual development and slow intellectual development, speech delay, etc. And the reason lies in the lack of oxytocin contained in breast milk and produced upon contact with it … Involuntary leg movements during sleep (restless legs syndrome) associated with depressive disorder have also been associated with oxytocin deficiency. Decreased interest in social interaction with depression is also the fault of the lack of this connection.

The group of pathologies associated with a decrease in secretion or impaired absorption of oxytocin also includes bipolar disorder and autism spectrum disorder (autism), schizophrenia, etc.

Autism Spectrum Disorder (ASD)

Studies show that children with ASD have lower blood levels of oxytocin than normal. In addition, there is a clear connection between the severity of symptoms and the level of the hormone: the less it is, the worse the child's social interaction. And this is not just the case with autism: the same addiction manifests itself in children with other disorders.

It is interesting!

Oxytocin or placebo?

Oxytocin is considered safe for human clinical trials. It is administered, as a rule, in the form of an injection of a solution into the nasal passages. Oxytocin easily penetrates the blood-brain barrier into the brain. But it has one very interesting effect associated with placebo.

As it turned out, even the introduction of a "dummy" drug-placebo instead of oxytocin causes positive reactions. Even in studies with autistic children, subjects with severe oxytocin deficiency received an increased benefit from placebo compared to other participants.

So the version appeared that the introduction of a placebo under the guise of oxytocin causes the body to produce its own hormone.

Alexithymia: I don't know how I feel

Alexithymia is the inability to describe your emotions. In modern medicine, it is considered a neuropsychiatric characteristic of a person, not related to the level of intellectual development. That is, a person knows everything about emotions, but he is not able to describe what he is experiencing. This disorder is often observed in patients with anorexia, bulimia, depressive and sexual disorders, and various mental disorders.

Scientists believe that alexithymia occurs due to oxytocin deficiency. Thus, anorexia nervosa with alexithymia occurs in people with low blood levels of this hormone.

Social hierarchy and oxytocin

Although humans are more evolutionarily advanced creatures than rhesus monkeys, we have a lot in common (and studying the behavior of monkeys in groups is easier and more ethical). And scientists studied it, including through the introduction of oxytocin.

As it turned out, if alpha males artificially increase the concentration of oxytocin in the blood, there will be fewer conflicts over place in the flock. Dominant persons become less aggressive, but subordinates, on the contrary, become more confident.

Interestingly, the drug was not administered to all males. It turned out to be quite enough to change the behavior of one of them with the help of a hormone, and the relatives began to read his non-verbal signals and adapt. So the hierarchy in the herd changed. Scientists have called this phenomenon "behavioral synchronization."

Trust, xenophobia and altruism

Various clinical studies have shown that oxytocin reduces anxiety and increases our level of trust in others. At the same time, scientists have demonstrated that this neurotransmitter is actively produced in the pituitary gland by stroking (that's why we love light massage!), Hugs and other pleasant touches to us. Moreover, in stable couples, touch can work so well that it can be used in childbirth for safe pain relief (Scientific Reports).A powerful release of oxytocin is also noted during intercourse, especially at the time of orgasm in both sexes.

It is logical that with the growing trust in people, the introduction of oxytocin reduces the level of xenophobia - a negative attitude towards “outsiders”. Conversely, the less oxytocin, the more severe the xenophobia.

Scientists have also studied how this neurotransmitter can influence the propensity for altruism. As it turned out, you can't get altruism out of nothing. If a person has never had altruistic inclinations, then even after the introduction of an additional portion of oxytocin, they will not appear. But in "experienced" altruists, the degree of manifestation of this character trait under the influence of oxytocin increases.

Spirituality and sublime love

It is not for nothing that oxytocin is called the hormone of love, but not only intersexual. He is responsible for love for one's neighbor and living beings in general. For example, in a 2016 experiment, a group of male volunteers received oxytocin, after which they meditated. The second group practiced meditation without injecting the hormone. As it turned out, the introduction of the substance increases the level of love for the world around, the feeling of an inextricable connection between the person himself and other living beings, activates thoughts of peace and gratitude. The control group did not mention such expressed emotions.


Ecstasy and oxytocin

Ecstasy, aka methylenedioxymethamphetamine (MDMA), in addition to activating the release of serotonin, dopamine and norepinephrine, increases the production of oxytocin. Thus, he sharpens the feeling of closeness and sympathy for other people. True, with the use of ecstasy there is a danger of overdose - in this case, the drug becomes neurotoxic, dangerous to health and life.

Let's summarize

It is necessary to distinguish between the effects of oxytocin-hormone and oxytocin-neurotransmitter. In the latter case, it acts only in the neurons of the brain as a modulator: it increases the flow of some stimuli and decreases the influence of others. In fact, from the chaos of incoming nerve impulses from all senses, oxytocin filters those that shape a certain social behavior of a person.

Oxytocin makes a social personality pleasant in all respects out of closed, wary, distrustful loners. Aggressors calm down and become more balanced, people suffering from external pressure gain self-confidence. True, at the same time the level of vigilance decreases and the degree of naivety increases, which, of course, makes a person safer for the environment, but at the same time increases various risks for himself - alas, our society is still far from ideal.

"Games" of scientists with hormones - oxytocin and vasopressin - give hope for the emergence of effective methods of correcting various mental disorders (and not only). Oxytocin preparations may be useful for patients who have had their pituitary gland removed or malfunctioning for any reason. Finally, oxytocin could be used to correct conditions associated with pathological overeating - after all, it is also tied to pleasure.


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