It used to be thought that the hormone oxytocin was produced mainly in the female body. But it turns out that it plays an important role in male sexuality as well. RIA Novosti investigated how this protein controls sexual behavior and why the hormone of calm, empathy, and trust sometimes causes anxiety and suspicion.
The love hormone
Oxytocin is a small protein, a peptide of nine amino acids. It is produced by certain brain cells – hypothalamic neurons. It affects female reproduction, lactation, and childbirth, as well as determining the model of maternal behavior, so it is often called the “female” hormone.
Oxytocin also affects the psycho-emotional sphere: it makes people trusting and benevolent, especially within their own social group or family. But the most popular and well-known role of oxytocin, which is why it is called the “love hormone”, is its relationship to reproductive function, sexuality, and romantic emotion.
Its effects on female sexuality are fairly well studied. It is proved that it stimulates the smooth muscles of the uterus, increases the frequency and amplitude of its contractions, enhances sexual arousal and orgasm in women. But it turned out that men, too, have physiological mechanisms that control oxytocin.
A test on rats
Oxytocin is transmitted from the brain to various parts of the body with blood and along with neural circuits through structures called synapses. Japanese researchers, led by Professor Hirotaka Sakamoto of the University of Okayama, along with colleagues from the United States and the United Kingdom, hypothesized that some of the oxytocin chains reach the lumbar region and control sexual function in men.
To test this hypothesis, the authors injected the love hormone into the spine of male rats, which increased the animals’ sexual activity. It turned out that oxytocin spurred neurons in an area of the spinal cord called the spinal ejaculation generator (SEG) – these neurons control the muscles at the base of the penis.
Then scientists injected the animals with a substance that inhibited the activity of the oxytocin receptors. Sexual activity and the number of ejaculations decreased in the rodents. According to researchers, this confirms the key role of the love hormone in the sexual function of males – it fully justifies its name.
Oxytocin, produced in the hypothalamus, activates spinal ejaculation generator (SEG) neurons through the interaction of oxytocin receptors (OXTRs) with gastrin-releasing peptide neurons
Oxytocin produced in the hypothalamus activates spinal ejaculation generator (SEG) neurons through the interaction of oxytocin receptors (OXTRs) with gastrin-releasing peptide (GRP) neurons
The oxytocin paradox.
However, it is not entirely clear: oxytocin production is the cause or consequence of sexual arousal. American scientists from the University of Utah prepared a review in which they combined the results of work on this topic over the past twenty years.
And they were surprised to find that when the volunteers were given oxytocin drops in the nose, their sexual arousal did not increase compared to the control group.
But the opposite situation was observed: when aroused, oxytocin levels increased in people, regardless of gender. The hormone promoted an erection in men and lubrication secretion in women.
Maximum levels of the love hormone were recorded, according to studies, during and after orgasm. In men, it provides a rapid release of sperm, and in women, it stimulates uterine contractions, helping the male sex cells to reach their goal – the egg.
Oxytocin levels in men return to normal about half an hour after ejaculation. It is with this, according to scientists, associated with the so-called “feeling of satiation” that occurs immediately after intercourse.
Moreover, those who received oxytocin intranasally before sexual intercourse had a brighter orgasm, a deeper “feeling of satiation”, and did not want to repeat the intercourse for a long time. It turned out that the hormone was also responsible for the relaxed state of calm that occurs in men after sex.
Perhaps, the authors of the review suggest, the main task of the love hormone is to create a special feeling after sexual intercourse. And here it is interesting to consider its impact on the psycho-emotional sphere of the man as a whole.
The hormone of trust and … suspicion
The men involved in the experiments most often received oxytocin through the nose. Such experiments on women are not safe: this substance strongly affects their reproductive function. So the psychotropic effect of the hormone has been better studied just on men.
Numerous studies have shown that oxytocin decreases anxiety, tension, and restlessness in men, so they become more open and often look interlocutor in the eye, better understand and feel people, trust them. Such a state helps the beginning and development of romantic relationships.
Recent experiments on mice showed that after mating and release of oxytocin males become calmer and bolder, less reactive to stress factors, and not so actively avoid dangerous situations. Scientists attribute this to the fact that the bulk of the hormone is produced in the hypothalamus, the part of the brain that regulates the endocrine system. This is also where all the positive feelings associated with it arise.
But there is another area of the brain that also produces oxytocin-the supporting nucleus of the marginal stratum of the amygdala. Its regular activation causes upsets and depressions, and from there come signals of danger and anxiety
But there is another area of the brain that also produces oxytocin-the supporting nucleus of the amygdala fringe. Its regular activation causes disorders and depressions, from there come signals of danger and anxiety.
When the researchers injected the hormone directly into the parts of the brain with which neurons of the amygdala marginalis support nucleus connect, the normally unstressed mice showed signs of anxiety.
Although the authors found oxytocin neurons in the amygdala in both males and females, it turned out that in the latter, stress more actively enhances the hormone’s production. According to the researchers, this explains why anxiety disorders occur more frequently and are more severe in females than in males.