Wed. May 22nd, 2024

Mammalian neurohypophysial oxytocin. Hypothalamic supraoptic and paraventricular nuclei make and store oxytocin.

Oxytocin USA is crucial for intimacy during and after birth. It’s secreted during labour to promote birth, mother connection, and breastfeeding. Positive feedback causes birth and milk expulsion.

Researchers have studied oxytocin’s role in orgasm, social recognition, pair bonding, anxiety, and maternal behaviour. Hence, “bonding hormone.” Oxytocin may promote ethnocentrism, mixing in-group trust and empathy with outsider distrust and rejection. Violence is connected to polymorphisms in the OXTR gene.

It’s on the WHO’s List of Essential Medicines, which comprises the most important pharmaceuticals.

Vasopressin Chemistry

Nine amino acids make up oxytocin (a nonapeptide). Isolucine-glutamine-asparagine-cysteine-proline-leucine. amide-glycine (CYIQNCPLG-NH2) 1007 daltons make up oxytocin. 2 micrograms of peptide equal 1 IU of oxytocin.

New world monkeys’ oxytocin structure is unusual. The oxytocin gene has a single in-frame mutation that alters the 8th amino acid (proline for leucine).

Physiologically active oxytocin is the octapeptide “oxytocin disulfide” (oxidised form), although it also exists as the dithiol nonapeptide oxytoceine. Open chain oxytoceine (the reduced form of oxytocin) may act as a free radical scavenger (by providing an electron to a free radical). It can be oxidised back to oxytocin through the dehydroascorbate ascorbate redox pair.

oxytocin’s structure is similar to vasopressin’s (cys – tyr – phe – gln – asn – cys – pro – arg – gly – NH2) 1953: Vincent du Vigneaud synthesised oxytocin and vasopressin.

Only oxytocin and vasopressin act distantly. Oxytocin neurons produce corticotropin-releasing hormone and dynorphin. The oxytocin- and vasopressin-producing cells are adjacent. Excitable, action-potential-generating neuroendocrine neurons.


Oxytocin affects the brain and hormones. Oxytocin affects high-affinity receptors. Oxytocin needs Mg2+ and cholesterol. Class I rhodopsin GPCR.

Oxytocin mimics pituitary gland production. Behavioral effects of oxytocin may be from centrally projecting neurons, not pituitary or collateral neurons. Amygdala, hypothalamus, septum, accumbens, and brainstem neurons have oxytocin receptors.


Oxytocin releases milk from nursing women’s mammary glands into subareolar sinuses. Spinal nerves tell the hypothalamus about newborn nipping.

Stimulating oxytocin-producing neurons causes intermittent bursts of action potentials and pituitary oxytocin pulses.


During phase 2 and 3, oxytocin causes contractions. In the early weeks of breastfeeding, oxytocin causes painful contractions. This aids in postpartum placental coagulation.

oxytocin-deficient mice reproduce and birth normally.


Oxytocin reduces cytokines. Social interactions boost oxytocin, which aids wound healing.

Marazziti and coworkers used heterosexual couples. Social involvement increases plasma oxytocin, which speeds wound healing. Oxytocin may decrease inflammation and expedite wound healing. This study indicates healthy social interactions.

Blocking the oxytocin receptor in female mice’s mPFC lowered male mice’s social drive throughout the estrous cycle’s receptive phase.

Uncertain: oxytocin and sexual response. Men and women’s plasma oxytocin increased after orgasm, according to two uncontrolled studies. Plasma oxytocin levels are greater 5 minutes after self-arousal. One study revealed oxytocin’s effects on muscle contractibility may promote sperm and egg transport. Peptides and Sarms USA

According to a study comparing oxytocin serum levels before and after sexual stimulation, it improves sexual arousal. Genital stimulation increases oxytocin after orgasm, study shows. Nipple/areola, genital, and/or genital tract stimulation may boost oxytocin in animals.

Murphy et al. (1987) found oxytocin increases during sexual excitation but not climax. Men’s plasma oxytocin rose after orgasm, but not statistically. Scientists say these changes may indicate reproductive tissue contractility.

Oxytocin generates feelings of contentment, tranquilly, and security. Oxytocin may inhibit behavioural control, fear, and anxiety, allowing orgasm. Oxytocin reduces anxiety and stress when combined with social support.

It reduces urine output like vasopressin. Oxytocin promotes sodium excretion (natriuresis) in animals, and in humans, excessive doses can induce hyponatremia.

Some rats have oxytocin receptors and the hormone may increase cardiomyocyte differentiation during embryonic heart development. No cardiac insufficiencies have been reported in oxytocin-deficient animals.

Oxytocin lowers ACTH and cortisol, making it a vasopressin antagonist.


Oxytocin may treat repetitive and affiliative autism behaviours. Oxytocin helped adults’ emotive speaking. Oxytocin decreased recurrent behaviours and improved emotional interpretation in adults. Intranasal oxytocin helps autistic kids as young as 12 identify emotions.

Deletion of the oxytocin receptor gene has been associated to autism (OXTR). Caucasian, Finnish, and Han samples support OXTR-autism relationship. Autism may result from OXTR methylation. Oxytocin improves autism symptoms. Oxytocin’s advantages and risks in autism therapy require more study. Researchers don’t recommend utilising oxytocin to treat autism outside of formal trials.

Fear, trust

In a risky investment game, oxytocin-treated participants demonstrated more trust. Subjects talking with a computer showed no such reaction, demonstrating oxytocin didn’t increase risk aversion.

Nasal oxytocin suppresses the amygdala, reducing fear (which is thought to be responsible for fear responses). Activating an inhibitory amygdala circuit reduces fear in rats. Researchers say intranasal oxytocin increases envy and Schadenfreude.

Oxytocin builds confidence. Emotional disclosure shows trust. Intranasal oxytocin users report negative situations more emotionally. Intranasal oxytocin increases trust. Intranasal oxytocin made neutral-looking human faces appear more trustworthy. Oxytocin reduces betrayal dread. Even when absent from a dialogue, oxytocin improved trust.

Oxytocin somewhat increases trust. In a study, “investors” determined how much to give a “trustee.” Trustee was trustworthy, untrustworthy, or neutral. Intranasal oxytocin enhanced trusting donors’ contributions. Participants who received oxytocin didn’t contribute more to the untrustworthy trustee, suggesting that it only promotes trust when there’s no reason to be sceptical. OXTR gene variations generate various betrayal emotions. CT responds fiercely to treachery.

Oxytocin controls male-female social distance and may boost sexual desire and relationship bonding. Monogamous men increased their distance from an attractive lady by 10 to 15 cm after using oxytocin nasal spray. Researchers suggest oxytocin encourages monogamy.

Intranasal oxytocin increased generosity by 80% in the Ultimatum Game, but not in the Dictator Game. Researchers induced perspective-taking in the Ultimatum Game by not disclosing players their position in the Dictator Game. Methodological problems surround oxytocin’s role in trust and kindness.

Intranasal oxytocin increases male empathy. Oxytocin probably enhances eye-gazing. Oxytocin affects cognitive vs. emotional empathy.


Oxytocin inhibits memory and learning. Oxytocin can prevent unpleasant memory recall. Oxytocin aids learning and memory. Intranasal oxytocin increases men’s smile recollection. They fear and recognise positive social cues better.


Rats get spontaneous erections after CSF-injected oxytocin. Oxytocin receptor antagonists suppress noncontact erections. Oxytocin improves female rats’ sexual receptivity, according to studies using antagonists.


During sexual activity, oxytocin helps prairie voles form monogamous pairs. Vasopressin affects men, too. Oxytocin impacts animal and human social behaviour. Human and canine oxytocin levels rose after five to 24 minutes of contact in 2003. This may help human-dog bonding.


After birth, female rats given oxytocin antagonists aren’t maternal. After oxytocin infusions, virgin female sheep adopt alien lambs. Oxytocin starts maternal behaviour, not its maintenance; it’s higher in moms after interacting with unknown children.


Animal studies show oxytocin reduces withdrawal and medication tolerance (opiates, cocaine, alcohol). MDMA (ecstasy) improves love, empathy, and connection through activating serotonin 5-HT1A receptors. Buspar (buspirone) activates 5-HT1A oxytocin receptors.


High oxytocin is associated to romance. Long-separated spouses who lack physical love may experience anxiety. Oxytocin lessens couples’ anxiety.


Recent study reveals that oxytocin neurons in the para-ventricular hypothalamus lessen appetite and that other neurons encourage eating by blocking them. Prader-Willi syndrome may be caused by a shortage of oxytocin neurons.


Oxytocin can promote positive sentiments, such as bonding, toward “in-group” members and “out-group” members. Society categorises people by race, therefore it demonstrates in-group and out-group tendencies (Caucasian, African American, Latino, etc.).

In a study on race and empathy, nasal oxytocin increased responses to in-group sad expressions compared to out-group ones. This shows that oxytocin may be important in our ability to empathise with other races, which may translate into a desire to help individuals in stressful situations. One race may help another in distress.

Oxytocin promotes in-group lying. When oxytocin was given and a good outcome was expected, in-group dishonesty soared.

Both situations show in-group favouritism. Oxytocin is linked to intergroup conflict and group membership. Nasal oxytocin promotes in-group defence during conflict.

Despite dedication to the conflict, oxytocin was connected to protecting vulnerable in-group members. Similarly, oxytocin favours in-group over out-group values. Intergroup dynamics are linked to oxytocin. Oxytocin influences group interactions. In-group bias is obvious in smaller groups, but it may even affect an entire country, causing national excitement.

Dutch researchers showed that oxytocin increased in-group prejudice and lowered acceptance. People appreciate their country’s flag when exposed to oxytocin but overlook other artefacts. This hormone may cause xenophobia. Oxytocin influences individuals internationally, where the in-group is a “home” country and the out-group is all other nations.


Oxytocin promotes trust and connection. “Love hormone” oxytocin Oxytocin boosts prosocial behaviour and more. Oxytocin controls anxiety; it doesn’t generate it. Fear and anxiety both explain oxytocin. Oxytocin may encourage approach/avoidance of social cues or increase the prominence of social stimuli, drawing animals’ or humans’ attention to them.

Intranasal oxytocin helps identify nasty facial expressions. Distaste is infectious. Oxytocin makes inputs that signal contamination more relevant, speeding up the response. Compared to placebo, oxytocin improved people’s terror perception. Increased social memory lessens fear from oxytocin. Rats with higher oxytocin receptors fear conditioned stressors more. Oxytocin increases rats’ aversive social memory, making them more afraid.

Oxytocin’s gendered effects complicate its aim. Women respond faster to social signals when given oxytocin. Men don’t have increased amygdala activity after taking oxytocin. Oestrogen affects women’s enhanced danger processing. Estrogen enhances oxytocin and amygdala receptor binding.