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 Заголовок сообщения: Oxytocin and human behavior
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http://www.nature.com/mp/journal/vaop/n ... 8112a.html

Lower CSF oxytocin concentrations in women with a history of childhood abuse

Heim C, Young LJ, Newport DJ, Mletzko T, Miller AH, Nemeroff CB.

Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, WMRB, Atlanta, GA, USA.

Early-life disruption of the parent-child relationship, for example, in the form of abuse, neglect or loss, dramatically increases risk for psychiatric, as well as certain medical, disorders in adulthood. The neuropeptide oxytocin (OT) plays a seminal role in mediating social affiliation, attachment, social support, maternal behavior and trust, as well as protection against stress and anxiety. We therefore examined central nervous system OT activity after early-life adversity in adult women. We measured OT concentrations in cerebrospinal fluid (CSF) collected from 22 medically healthy women, aged 18-45 years, categorized into those with none-mild versus those with moderate-severe exposure to various forms of childhood abuse or neglect. Exposure to maltreatment was associated with decreased CSF OT concentrations. A particularly strong effect was identified for emotional abuse. There were inverse associations between CSF OT concentrations and the number of exposure categories, the severity and duration of the abuse and current anxiety ratings. If replicated, the association of lower adult CSF OT levels with childhood trauma might indicate that alterations in central OT function may be involved in the adverse outcomes of childhood adversity.

Molecular Psychiatry advance online publication, 28 October 2008; doi:10.1038/mp.2008.112.


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Oxytocin increases gaze to the eye region of human faces

Guastella AJ, Mitchell PB, Dadds MR.

School of Psychology, University of New South Wales, Kensington, Sydney, Australia.

BACKGROUND: In nonhuman mammals, oxytocin has a critical role in peer recognition and social approach behavior. In humans, oxytocin has been found to enhance trust and the ability to interpret the emotions of others. It has been suggested that oxytocin may enhance facial processing by increasing focus on the eye region of human faces. METHODS: In a double-blind, randomized, placebo-controlled, between-subject design, we tracked the eye movements of 52 healthy male volunteers who were presented with 24 neutral human faces after intranasal administration of 24 IU oxytocin or placebo. RESULTS: Participants given oxytocin showed an increased number of fixations and total gaze time toward the eye region compared with placebo participants. CONCLUSIONS: Oxytocin increases gaze specifically toward the eye region of human faces. This may be one mechanism by which oxytocin enhances emotion recognition, interpersonal communication, and social approach behavior in humans. Findings suggest a possible role for oxytocin in the treatment of disorders characterized by eye-gaze avoidance and facial processing deficits.

Biol Psychiatry. 2008 Jan 1;63(1):3-5. Epub 2007 Sep 21.


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http://news.bbc.co.uk/2/hi/health/7412438.stm

Trust drug may cure social phobia

A nasal spray which increases our trust for strangers is showing promise as a treatment for social phobia, say scientists from Zurich University.
They found that people who inhaled the "love hormone" oxytocin continued to trust strangers with their money - even after they were betrayed.
Brain scans showed the hormone lowered activity in the amygdala - a region which is overactive in social phobics.
Drug trials are under way and early signs are promising say the scientists.
Nicknamed the "cuddle chemical", oxytocin is a naturally produced hormone, which has been shown to play a role in social relations, maternal bonding, and also in sex.
Lead researcher Dr Thomas Baumgartner said: "We now know for the first time what exactly is going on in the brain when oxytocin increases trust.
"We found that oxytocin has a very specific effect in social situations. It seems to diminish our fears.
"Based on our results, we can now conclude that a lack of oxytocin is at least one of the causes for the fear experienced by social phobics.
"We hope and indeed we expect that we can improve their sociability by administering oxytocin."

Powerful effect

Previous studies have shown that participants in "trust games" took greater risks with their money after inhaling the hormone via a nasal spray.
In this latest experiment, published in the journal Neuron, the researchers asked volunteer subjects to take part in a similar game.
They were each asked to contribute money to a human trustee, with the understanding that the trustee would invest the money and decide whether to return the profits, or betray the subject's trust by keeping the profit.
The subjects also received doses of oxytocin or a placebo via a nasal spray.
After investing, the participants were given feedback on the trustees. When their trust was abused, the placebo group became less willing to invest. But the players who had been given oxytocin continued to trust their money with a broker.
"We can see that oxytocin has a very powerful effect," said Dr Baumgartner.
"The subjects who received oxytocin demonstrated no change in their trust behaviour, even though they were informed that their trust was not honoured in roughly 50% of cases."
In a second game, where the human trustees were replaced by a computer which gave random returns, the hormone made no difference to the players' investment behaviour.
"It appears that oxytocin affects social responses specifically related to trust," Dr Baumgartner said.

Defence barriers

During the games, the players' brains were scanned using functional magnetic resonance imaging (fMRI).
The researchers found that oxytocin reduced activity in two regions which act as natural "defence barriers".
They are the amygdala, which processes fear and danger, and an area of the striatum, which helps to guide future behaviour, based on reward feedback.
The amygdala has been found to be extremely active in the brains of sufferers of social phobia.
Dr Baumgartner's colleague, Professor Markus Heinrichs, has begun a study where social phobia sufferers are given either oxytocin or a placebo, in combination with cognitive and behavioural therapy.
The trials are ongoing, but Dr Baumgartner said that early signs appear "promising".
The hormone could also be a candidate for treating patients with autism, he says.
"Autistic people also have a fear of social situations and have problems interacting, so it is very likely that oxytocin could help," he said.
"This hormone seems to play a very specific role in social situations so might be able to improve autism. But so far I am not aware of any studies."
Mauricio Delgado, a psychologist at Rutgers University, said: "This study has significant implications for understanding mental disorders where deficits in social behaviour are observed.
"While a degree of wariness may protect one from harm, being able to ''forgive and forget'' is an imperative step in maintaining long-term relationships.
"The reported oxytocin finding could provide a bridge for potential clinical applications."


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An extract from The Oxytocin Receptor System: Structure, Function, and Regulation

http://physrev.physiology.org/cgi/content/full/81/2/629 (рекомендую читать все по ссылке)

3. Sexual behavior in humans


It is well documented that levels of circulating OT (oxytocin) increase during sexual stimulation and arousal and peak during orgasm in both men and women (90, 92, 401). Murphy et al. (402) measured plasma OT and AVP (arginine vasopressin) concentrations in men during sexual arousal and ejaculation and found that plasma AVP but not OT significantly increased during arousal. However, at ejaculation, mean plasma OT rose about fivefold and fell back to basal concentrations within 30 min, while AVP had already returned to basal levels at the time of ejaculation and remained stable thereafter (402). Men who took the opioid antagonist naloxone before self-stimulation had reductions in both OT secretion and the degree of arousal and orgasm. A recent study confirmed that also in women peak levels of serum OT were measured at or shortly after orgasm (55). Carmichael et al. (91) reported that the intensity of muscular contractions during orgasm in both men and women were highly correlated with OT plasma level. This suggests that some of OT's effects may be related to its ability to stimulate the contraction of smooth muscles in the genital-pelvic area. Enhanced sexual arousal and orgasm intensity was reported in a woman during intranasal administration of OT. This response could be elicited only while she was taking daily doses of an oral contraceptive with estrogenic and progestogenic actions and might be caused through direct effects on sexual organs or sensory nerve sensitivity (13). Overall, beyond its peripheral effects on reproductive organs, OT might affect or sensitize cerebral neurons responsible for the cognitive feelings of orgasm and could thus serve as a physiological substrate for both sexual behavior and performances in humans as well as in animals (Table 5).


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