Oxytocin is probably one of the most well-known hormone type in human brain. It’s popularly known as love hormone. People also call this hormone as cuddle chemical, moral molecule, hug hormone and bliss hormone. This kind of hormone is known to have the significant role in human’s sexual reproduction system. In this article, we’ll cover all the things about oxytocin including its definition, effect, recent studies, potential benefits and chemical containment.
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What is Oxytocin?
Oxytocin is the hormone which is made in the brain by the hypothalamus. This hormone then will be secreted by pituitary gland which is located in the brain base. Chemically, this hormone is classified as the nonapeptide class. It’s the peptide class which has nine amino acids in it. Oxytocin has two roles as the hormone and brain neurotransmitter. Oxytocin is really important in the female childbirth process and also in male reproduction system. It also plays the vital role in social interaction like empathy, generosity and orgasm. There’re some studies conducted to deeply discover oxytocin and its effect to human. This part will be explained more on the ‘Oxytocin Studies’ section on this article.
Oxytocin Chemical Reaction
As we’ve mentioned previously, oxytocin is a peptide of nine amino acids (or known as nonapeptide) with the chemical sequence of cysteine-tyrosine-isoleucine-glutamine-asparagine-cysteine-proline-leucine-glycine-amide (Cys – Tyr – Ile – Gln – Asn – Cys – Pro – Leu – Gly – NH2, or CYIQNCPLG-NH2). The C-terminus part of its molecule is converted to primary amide. Thus, the disulfide bridge joins the cysteine moieties. Oxytocin itself has a molecular mass of 1007 Da.
We know previously that the complete structure of oxytocin is placed in placental mammals. However, a novel structure of oxytocin was recently found in tamarins, marmosets, and other new world primates. Genomic sequencing of the gene for oxytocin revealed a single in-frame mutation (thymine for cytosine). This will then cause in a single amino acid substitution at the 8-position (proline for leucine).
This finding was originally discovered by Lee Ag, Lee AG, Cool DR, Grunwald WC, Neal DE, Buckmaster CL, Cheng MY, Hyde SA, Lyons DM, Parker KJ on August 2011. Since then, there’re two other laboratories which have confirmed Pro8-OT and documented additional oxytocin structural variants in this primate taxon. On January 2015, Vargas-Pinilla successfully made sequence of coding regions of the OXT gene in other new world primates and identified these new types: Ala8-OT, Thr8-OT, and Val3/Pro8-OT. Next, another research on 2015 has found the new variant called Phe2-OT in howler monkeys.
The active form of oxytocin, popularly known as the octapeptide “oxytocin disulfide”, can be commonly measured by RIA and/or HPLC techniques. However, oxytocin has also the form of a reduced straight-chain (non-cyclic) dithiol nonapeptide which is called oxytoceine. It’s said that oxytocin can act as a free radical scavenger, as donating an electron to a free radical allows oxytocin to be re-oxidized to oxytocin via the dehydroascorbate or ascorbate redox couple.
We can’t talk oxytocin without mentioning vasopressin. These two are the nonapeptides with one disulfide bridge in human brain. The difference between oxytocin and vasopressin is on their two substitutions in their amino acid sequence which are Cys – Tyr – Phe – Gln – Asn – Cys – Pro – Arg – Gly – NH2 (the bold sequences are the difference). Oxytocin and vasopressin were isolated and their total synthesis reported in 1954.
Oxytocin and vasopressin are the only known hormones released by the human posterior pituitary gland to act at a distance. However, oxytocin neurons make other peptides, including corticotropin-releasing hormone and dynorphin, for example, that act locally. The magnocellular neurosecretory cells that make oxytocin are adjacent to magnocellular neurosecretory cells that make vasopressin. These are large neuroendocrine neurons which are excitable and can generate action potentials.
Oxytocin hormones functions in men and women play important roles for emotions, love, or feeling reactions. Thus, here are the functions of oxytocin hormones for people.
1. Oxytocin in Women
In short, oxytocin plays the important role in two things of women reproduction systems which are childbirth process and breast feeding. For women, oxytocin is responsible for signaling contractions of the womb during labor. The hormone will stimulate the uterine muscles to contract and then the labor begins. It can also increase the production of prostaglandins. This will then move labor along and increase the contractions even more.
The reaction of oxytocin in women’s body has inspired researchers to create the synthetic oxytocin. This synthetic oxytocin can be induced to women who have problems in doing labor. For those who can’t make the natural labor, doctor usually will give them synthetic oxytocin so that they can start the labor process.
This oxytocin works by making the birth contraction stronger when the labor process is slowing. After women give birth, oxytocin help the lactation by transporting the milk to the women’s breast. Oxytocin which is secreted in the brain can cause the milk to be produced so that the new born babies can get the milk from their mother.
- Oxytocin effect on Social Interaction
It’s known that the oxytocin which is transported throughout bloodstream will significantly affect women uterus and lactation. However, the secretion of oxytocin to the different regions in our brain can also affect the emotional, cognitive and social interaction. The popular study conducted by Inga Neumann shows that that oxytocin can create a “pro-social behaviors” and emotional responses which will then contribute to relaxation, trust and psychological stability.
Another study states, “the hormone does not act alone in the chemistry of love, but is “just one important component of a complex neurochemical system that allows the body to adapt to highly emotive situations.” It’s also known that brain oxytocin can also reduce stress responses, including anxiety – and these anxiolytic effects have been demonstrated in a number of species.
Meanwhile, one of popular term ‘love hormone’ studies was published in 2012. It revealed oxytocin levels in new lovers versus those in single people. This research showed that there were high levels of the hormone in the first stages of romantic attachment, and that these were sustained for six months.
2. Oxytocin in Men
How about the effect of oxytocin for male? Well, if we compare the impact of this oxytocin to women’s body, it can be said that oxytocin plays less important role in men’s reproduction system. However, oxytocin does have the function in the transportation of male’s sperm. Oxytocin is also said to have the effect on the production of testosterone in male testes.
- Oxytocin Effect During Sex
Oxytocin hormones functions both men and women, sexual activity can stimulate the secretion of oxytocin which plays the significant act in orgasm and erection. In female, it’s known that the higher number of uterine motility may help sperm to reach their destination.
However, the reason of this phenomenon has not been deeply understood. Some researchers think that oxytocin may play a role in the experience of sexual orgasm which gives the correlation between the concentration of oxytocin and the intensity of orgasm.
Oxytocin and Emotional Connection
1. In 2013, there was a study titled Oxytocin: the monogamy hormone? This research shows the brain scans of male who had been given oxytocin or placebo via a nasal spray. The oxytocin was associated with activation of the men’s reward centers in their brains. The oxytocin was also correlated with greater feelings of attraction to male’s partners versus other women in photographs. Previously, the similar research about this topic had been conducted with the title A hormone can help keep men faithful. This study was published in the Journal of Neuroscience in November 2012:
2. In January 2014, the study called “High oxytocin levels trigger oversensitivity to emotions of others.” Was released. This study shows that Oxytocin hormones functions, the people who have been previously affected by oxytocin nasal spray will have more intense facial expressions of emotion than the people who haven’t been given oxytocin nasal spray.
3. Another study found out that oxytocin will make you more extroverted. In 2011, research paper in Psychopharmacology gave results from intranasal oxytocin improving self-perception in social situations, amplifying personality traits such as warmth, trust, altruism and openness.
4. In 2014, the different kind of study was conducted. This study revealed that the oxytocin also can encourage us to lie, besides its ability to allow human to love. It found out that participants given oxytocin were more likely to lie for the benefit of the group.
5. We have known previously that the oxytocin has the positive impact to our social attitude. It’s said that oxytocin can help us the build the trust feeling and connection between people who do interaction. Based on this fact, oxytocin has been popularly known as the love hormone. Actually, Oxytocin possess more complicated and broader impact to human’s social behavior.
Research showed that the oxytocin is able to cause anxiety and fear, even though the reaction doesn’t directly cause the fear or anxiety feeling. One researcher believes that oxytocin can improve our avoidance to some social events. While another researcher thinks that oxytocin will improve the salience of some social events which will then cause human to give more attention to that kind of social events.
6. Another researcher has showed us that the oxytocin has the ability to decrease our fear. This can be done since oxytocin is able to inhibit the amygdala, which has the role to respond the fear. Scientists have done the experiment with the rodents and it revealed that oxytocin can really inhibit fear by creating such an inhibiting circuit in the amygdala. The other researches said that oxytocin can possibly cause more improvement to all of human emotions. The experiments have been conducted to understand the effect of oxytocin to our emotions.
People who are previously given the oxytocin will have the faster response to the disgust’s facial expression compared to those who are not given the oxytocin. Another experiment also showed us that oxytocin can effectively improve the ability to response the fear’s face expression. Oxytocin can create the quicker fear responses by increasing the maintenance of our social memories.
7. Oxytocin is also said to have the capability as an antidepressant. Previously, the experiment has been conducted using the depression model in animal. It showed that oxytocin can create the similar effect like antidepressant in that kind of depression model. It gives us hope that this effect can also be applied to human’s depression model. It’s known that sidenafil can effectively improve the number of oxytocin secretion in the brain. By using this result, researchers believe that the sildenafil can be the promising alternative for antidepressant drugs for human.
Studies about Oxytocin
Many studies done in the past 15 years have tried to study the relationship between autism and oxytocin. In 1998, Modahl et al., in their study found significantly lower levels of oxytocin in blood plasma of autistic children. Five years later, in 2003, Hollander and associates found a decrease in autism spectrum repetitive behaviors when oxytocin was administered intravenously. Further in 2007, in another study Hollander et al., reported that oxytocin helped autistic adults retain the ability to evaluate the emotional significance of speech intonation.
More work is definitely required to investigate the role of oxytocin in autism, but present work is definitely showing a ray of hope in finding a role for oxytocin in treatment of autism. Oxytocin activates “social” brain regions in children with autism. A research study involving 17 children with autism spectrum disorders, published in December 2013, used functional magnetic resonance imaging (fMRI) to see differences created by oxytocin in brain responses to social and non-social pictures. Although this was a small study, the researchers found “oxytocin temporarily normalized brain regions responsible for the social deficits seen in children with autism.”
1. A researcher named Kovacs conducted the effect of oxytocin to human’s body. He found out that the oxytocin can actually decrease our craving feeling. He made an experiment by inserting oxytocin to the rodents who have high addiction to morphine, heroin and cocaine.
Based on the experiment, rodents would have lower interest to that drugs after the oxytocin is injected to their bodies. Another study also showed that oxytocin is able to decrease our craving for sweet foods. This finding can be very beneficial since it can be used as the alternative method to reduce the body weight. Another experiment has also been performed to rats and it showed that oxytocin can create such a calming effect to that rats.
2. Another promising effect of oxytocin comes from Vitalo. He and his partners conducted the study to understand the effect of oxytocin in healing an injury. He successfully proved us that the injection of oxytocin in the rats can effectively increase the ability to heal the injury.
3. Another researcher named Legros has found out that oxytocin has the opposite effect with the stress hormone. If the stress hormone produced is lower, we will have less stress and it can then increase our immunity. This can cause the quicker recovery. This is the promising effect that needs to be verified by further researches.
One study also has shown the great effect of oxytocin in repairing the intestinal injury. That study revealed that oxytocin can improve the number of prostaglandin E2 and can heal the intestinal injury better. It’s also said that oxytocin can protect us from that kind of intestinal injury
Oxytocin Potential effects
Besides its many effect to both human reproduction system and physiological matter, oxytocin also has some promising effects. Here’re some great potential effects that we may get from this hormone:
- As we’ve mentioned previously that the potential use of oxytocin as drug is really huge. Based on previous studies, oxytocin is found to be effective in helping to cure some social diseases. On the previous paragraph we’ve mentioned the effect of oxytocin to our emotion especially its correlation to our anger and anxiety. As the oxytocin itself is really complex, there must be other many great effects of that substance which can be used to overcome some serious social disorders. Oxytocin can be the promising alternative for the therapist activities for other social or non-social diseases.
- Oxytocin effect to male, especially to male reproduction system, should also be considered as the opportunity. Based on the study conducted to the rats, oxytocin can cause the improvement of their ejaculation. Oxytocin which is inserted to the rats shows the effect of helping penis erection. This can then be linked to the possibility to improve the number of sperm produced. This effect can be discovered more to see if there’s any possibility for making oxytocin as the cure for male reproduction-related disorders, like premature ejaculation. Hopefully, this oxytocin can be used as the alternative tools for the premature ejaculation theraphy.
Even though oxytocin has some great effect to human’s body and emotion, it can also give drawbacks for certain people. In men, the high level of oxytocin has been associated with the prostatic hyperplasia. This is one of the possible negative impact of oxytocin to male reproduction system. In women, the low level of oxytocin can create difficulties in breastfeeding activity.
There’re also other researches that showed that low oxytocin in brain can cause the autism, depression and other mental related illness. In short, there must be further studies conducted to give us better understanding about this oxytocin in men and women, the chemicals of love. If we have deep understanding about oxytocin and its effect to our body, it’s not impossible to have oxytocin as one of the most powerful substance to help improving human’s health according to the emotional connections.
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